WO2000063487A1 - Absorbent articles and methods for producing the same - Google Patents
Absorbent articles and methods for producing the same Download PDFInfo
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- WO2000063487A1 WO2000063487A1 PCT/US2000/010326 US0010326W WO0063487A1 WO 2000063487 A1 WO2000063487 A1 WO 2000063487A1 US 0010326 W US0010326 W US 0010326W WO 0063487 A1 WO0063487 A1 WO 0063487A1
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- Prior art keywords
- nits
- fibers
- absorbent
- cellulosic
- particles
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Classifications
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
- A61F13/534—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad
- A61F13/535—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad inhomogeneous in the plane of the pad, e.g. core absorbent layers being of different sizes
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/15577—Apparatus or processes for manufacturing
- A61F13/15617—Making absorbent pads from fibres or pulverulent material with or without treatment of the fibres
- A61F13/15634—Making fibrous pads between sheets or webs
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
- A61F13/534—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad
- A61F13/537—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer
- A61F13/53704—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer the layer having an inhibiting function on liquid propagation
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
- A61F13/534—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad
- A61F13/537—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer
- A61F13/53743—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer characterised by the position of the layer relative to the other layers
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
- A61L15/28—Polysaccharides or their derivatives
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
- A61L15/34—Oils, fats, waxes or natural resins
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/42—Use of materials characterised by their function or physical properties
- A61L15/50—Lubricants; Anti-adhesive agents
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/001—Modification of pulp properties
- D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
- D21C9/005—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives organic compounds
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/001—Modification of pulp properties
- D21C9/007—Modification of pulp properties by mechanical or physical means
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
- A61F2013/530437—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having a part with elevated absorption means
- A61F2013/530445—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having a part with elevated absorption means by defining a target or acquisition or vulnerability zone
Definitions
- Absorbent articles for collecting body exudates typically comprise bulky fibrous absorbent webs as the main absorbent material for collecting body fluids. These webs often collapse when wetted, resulting in decreased void volume and degraded body-fit after the article is wetted. They also often lack the ability to conform well to the body of a wearer. What is needed are improved absorbent articles or absorbent materials capable of overcoming various limitations of past approaches. More specifically, improved materials and articles are needed that are capable of providing at least one of improved body fit, conformability, maintenance of void volume when wet or absorbency.
- fibrous nits can be useful in absorbent articles, particularly when treated to have suitable particle size ranges, free flowing properties, or other properties.
- Methods have been developed for production of fibrous nits produced by disperging fibers, including disperging fibers in the presence of a nit conditioner which modifies nit properties such as particle size or other attributes.
- Related methods produce two or more kinds of nits which can be coupled for use in absorbent articles. Methods for incorporating the particles of the present invention into absorbent articles are also disclosed.
- FIG. 1 is a flowchart depicting one choice of process steps for preparing free- flowing particles for use in absorbent articles.
- FIG. 2 depicts a sanitary napkin of the present invention in cross-sectional view showing an intake member comprising a longitudinal pouch of nits.
- FIG. 3 is a cross-sectional view of an absorbent article of the present invention with a conformable intake member comprising free-flowing particles and further comprising a wicking barrier to impede fluid flow from a central absorbent member to an outer absorbent member.
- FIGS. 4A and 4B depict cross-sectional views of two versions of an absorbent article having a pouch of nits or free-flowing particles beneath an upper absorbent layer, wherein the pouch helps predispose the upper absorbent layer for upward flexing when the article is worn.
- FIG. 5 is a partial cutaway view of a sanitary napkin comprising a pouch of nits or free-flowing particles disposed between two absorbent layers.
- FIGS. 6A - 6C depict embodiments in which a central pouch of nits or free-flowing particles disposed on an absorbent layer can serve as a conformable intake member.
- FIG. 7 depicts a cutaway view of an absorbent core comprising a wicking barrier and a central absorbent member having an internal pouch of free-flowing particles.
- FIG. 8 depicts a partial sectional view of a pad comprising a central pillow filled with nits and/or other free-flowing particles.
- FIG. 9 shows a simple apparatus for measuring the angle of repose of free-flowing particles.
- FIG. 10 shows how the angle of repose is determined in a pile of free-flowing particles.
- FIG. 11 depicts apparatus used to measure permeability of free-flowing particles.
- FIG. 12 depicts a bottom view of the apparatus of FIG. 11.
- FIG. 13 is a flowchart for a method of preparing absorbent articles comprising nits that have been disperged twice.
- FIG. 14 is a flowchart for a method of preparing absorbent articles with two or more kinds of nits.
- FIG. 15 is an SEM micrograph of a eucalyptus nit made according to the present invention.
- FIG. 16 is an SEM micrograph of a eucalyptus nit with fibers projecting from the surface of the nit.
- FIG. 17 is an SEM micrograph of the cross-section of a eucalyptus nit prepared with a Maule disperger.
- absorbent article refers to devices which absorb and contain liquids such as body exudates, and, more specifically, refers to devices which are placed against or in proximity to the body of the wearer to absorb and contain the various exudates discharged from the body.
- biodegradable refers to the ability of a compound to ultimately be degraded completely into carbon dioxide and water or biomass by microorganisms and/or natural environmental factors.
- the free-flowing particles are substantially biodegradable.
- the entire absorbent article is substantially biodegradable.
- bulk and density are based on an oven-dry mass of a sample and a thickness measurement made at a load of 0.34 kPa (0.05 psi) with a 7.62-cm (three-inch) diameter circular platen. Thickness measurements of samples are made in a TAPPI-conditioned room (50% relative humidity and 23°C) after conditioning for at least four hours. Samples should be essentially flat and uniform under the area of the contacting platen. Bulk is expressed as volume per mass of fiber in cc/g and density is the inverse, g/cc.
- the term "cellulosic” is meant to include any material having cellulose as a major constituent, and specifically comprising at least 50 percent by weight cellulose or a cellulose derivative.
- the term includes cotton, typical wood pulps, nonwoody cellulosic fibers, cellulose acetate, cellulose triacetate, rayon, thermomechanical wood pulp, chemical wood pulp, debonded chemical wood pulp, milkweed, bacterial cellulose, and the like.
- debonders are chemicals which can be used to interfere with the normal hydrogen bonding that occurs between cellulosic fibers as they dry.
- Debonders generally comprise molecules with fatty portions or alkyl chains or other moieties that hinder hydrogen bonding.
- debonders are cationic, often comprising a quaternary amine group.
- a debonding agent which may be either cationic, nonionic or anionic in nature.
- the term "diaper” refers to an absorbent article generally worn by infants and incontinent persons that is worn about the lower torso of the wearer. 100
- the term “disposable” is used herein to describe absorbent articles which are not intended to be laundered or otherwise restored or reused as an absorbent article (i.e., they are intended to be discarded after a single use and optionally to be recycled, composted or otherwise disposed of in an environmentally compatible manner).
- 105 fibers at elevated consistency e.g., greater than 8% and typically greater than 10% consistency, such as from about 12% to about 25% or from about 18% to about 42%) to cause the fibers to rub against each other without excessive damage to the fibers.
- Devices commonly known as kneaders or dispergers can be used, though both terms are encompassed by the term "disperger” as used herein. In this process, the fibers frequently
- Disperging is sometimes called "dispersion" in the papermaking arts, where it has been applied to modify fiber properties and enhance ink removal in recycling operations. Below, methods are presented for adapting disperging operations for the deliberate generation of fibrous nits - typically held to be undesirable prior to the present invention.
- a "dispersant” is a chemical compound that helps maintain fine solid particles in a state of suspension and inhibits their agglomeration or settling in a fluid medium.
- the term “dispersant” is not to be confused with the aforementioned terms “disperging” and “dispersion” which, as used herein, refer to mechanical processing of fibers.
- a variety of exemplary dispersants are disclosed in US Patent No. 5,795,377,
- dispersants can also promote the breaking up of agglomerates of particles to form particle suspensions.
- dispersants known in the art are useful in preventing settling, deposition, precipitation, agglomeration, flocculation, coagulation, adherence or caking of solid particles in a fluid medium. Suitable dispersants include:
- organic polyelectrolytes including polycarboxylates, polysulfonates, polysulfates and polyphosphates; inorganic sulfonates, polyphosphates and silicates; and polymers containing polar groups such as polyacrylamides and polyols.
- synthetic polymer dispersants are the co-polymers of ethylenically unsaturated monomers with mono-ethylenically unsaturated carboxylic acids or their partially neutralized salts.
- Examples of useful monounsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, half esters or half amides of maleic, fumaric and itaconic acid, crotonic acids, alkyl acrylates and methacrylates containing 1-18 carbon alkyl groups, vinyl esters, vinylaromatic compounds, dienes, etc.
- 135 acids or mixtures of these monomers may also be used.
- examples include acrylic acid and methacrylic acid homopolymers and acrylic acid/methacrylic acid copolymers.
- polyacrylamides of use include polyacrylamides and polymethracrylamides and their N and N,N dialkyl derivatives containing 1-18 carbon alkyl groups.
- Exemplary of the sulfonic acid containing polymer dispersants are the
- Suitable sulfonated containing monomers include aromatic sulfonic acids (such as styrene sulfonic acids, 2-vinyl ethylbenzenesulfonic acid, 2-vinyl-3-bromobenzenesulfonic acid, 2- allylbenzene-sulfonic acid, vinylphenyl methanesulfonic acid), heterocyclic sulfonic acids
- sulfonated polymers include calcium lignosulfonates, formaldehyde modified napthalene sulfonates, sulfonated melamine-formaldehyde polymers and other sulfonated polymers.
- equivalent nit particle size is meant to be a measure of the equivalent diameter of a nit as if the nit were assumed to be spherically shaped.
- the equivalent nit particle size may be quantified, for example, by sieving a nit sample.
- the equivalent nit particle size for individual nits may be determined by an image analysis method wherein a nit sample is placed on a glass plate and a high-
- Nits useful in the present invention have an equivalent particle size that is greater than about 150 micrometers and less than about 10 millimeters (mm), more specifically greater than about 250 micrometers and less than about 5 mm, and suitably greater than about 300
- the term “extensible” refers to articles that can increase in at least one of their dimensions in the x-y plane by at least 10% and specifically at least 20%.
- the x-y plane is a plane generally parallel to the faces of the article.
- the term extensible includes articles that are stretchable and elastically stretchable (defined below).
- the article and the absorbent core can be extensible both in length and width.
- the absorbent article may only be extensible in one of these directions such as the longitudinal direction.
- the absorbent article comprising an absorbent core can, in addition to being extensible, also be "stretchable".
- the term "stretchable”, as used herein, refers to articles
- fiber or “fibrous” is meant to refer to a particulate material wherein the length to diameter ratio of such particulate material is greater than about 10 and specifically greater than about 20.
- a nonfiber or “nonfibrous”
- 180 material is meant to refer to a particulate material wherein the length to diameter ratio of such particulate material is about 10 or less.
- a bulk material e.g., the absorbent components of the article
- a bulk material is considered “flexible” if a straight, TAPPI-conditioned (50 percent relative humidity at 23°C) strip of the material 25 cm long with a cross-section of 1 cm x 1 cm can be bent 180°
- the strip is deformed such that the straight portions at the ends of the strip are at an angle relative to each other of at least 30°, with a perfectly straight strip defining an angle of 0°).
- free flowing refers to the ability of particulates to readily flow in response to shear forces typically encountered in the use of a sanitary napkin worn against a human body - forces similar to those obtained by gently rubbing fingers together
- Dry, loose, granular materials such as hardwood nits and polymethylurea (PMU) particles (hereafter described) are generally free-flowing under such conditions in contrast to materials such as clay which can deform but generally does not flow freely.
- PMU polymethylurea
- free-flowing particles will have an angle of repose (hereafter described) less than about 70° in the dry state and
- free flowing particles will generally have high ratios of consolidation pressure ( ⁇ ,) to cohesive strength (f c ) measured according to the Jenike shear flow test for particles, as specified in ASTM Test Method D6128-97, "Standard Shear Testing Method for Bulk Solids Using the Jenike Shear Cell,” herein incorporated by reference. This test examines interparticle shear forces under several
- Flowability Coefficient Flowability Coefficients of about 1 or less are indicative of a poorly flowing or nonflowing material.
- Free-flowing particles will generally have a Flowability Coefficient greater than about 2, specifically greater than about 2.5, more specifically greater than about 3, and most specifically from about 3.5 to about 10.
- Jenike shear testing is performed commercially by Jenike & Johanson, Inc. (Westford,
- the particles of the present invention also have an effective angle of internal friction ( ⁇ ) of about 67° or less, specifically about 60° or less, and most specifically about 57° or less.
- ⁇ effective angle of internal friction
- high yield pulp fibers are those papermaking fibers of pulps produced by pulping processes providing a yield of about 65 percent or greater, more specifically about 75 percent or greater, and still more specifically from about 75 to about 95 percent. Yield is the resulting amount of processed fiber expressed as a percentage of
- High yield pulps include bleached chemithermomechanical pulp (BCTMP), chemithermomechanical pulp (CTMP), pressure/pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp (TMCP), high yield sulfite pulps, and high yield Kraft pulps, all of which contain fibers having high levels of lignin. Characteristic high-yield fibers can have lignin content by mass of about
- high yield fibers can have a kappa number greater than 20, for example.
- the high yield pulp fibers, after being prepared by pulping and optional bleaching steps and prior to being formed into dry bales or webs, in one embodiment can also be characterized by being comprised of comparatively whole, relatively undamaged
- the high-freeness 200 Canadian Standard Freeness (CSF) or greater, more specifically 250 CSF or greater, and still more specifically 400 CSF or greater
- low fines content less than 25 percent, more specifically less than 20 percent, still more specifically less that 15 percent, and still more specifically less than 10 percent by the Britt jar test known to those skilled in the art of papermaking.
- CSF Canadian Standard Freeness
- low fines content less than 25 percent, more specifically less than 20 percent, still more specifically less that 15 percent, and still more specifically less than 10 percent by the Britt jar test known to those skilled in the art of papermaking.
- the high-freeness 200 Canadian Standard Freeness (CSF) or greater, more specifically 250 CSF or greater, and still more specifically 400 CSF or greater
- low fines content less than 25 percent, more specifically less than 20 percent, still more specifically less that 15 percent, and still more specifically less than 10 percent by the Britt jar test known to those skilled in the art of papermaking
- hydrophobic refers to a material having a contact angle of water in air of at least 90 degrees.
- hvdrophilic refers to a material having a contact angle of water in air of less than 90 degrees.
- a CAHN Surface Force Analyzer (SFA 222) can be used to measure hydrophilicity, as can a
- Nit refers to a generally particulate material comprising entangled fibers. Nits are sometimes also referred to as “neps, " “fiber bundles” or “fiber flakes.” A nit will also generally comprise capillaries or voids within its structure between the entangled fibers forming the nit and may have an irregular shape, though more regular
- Nits will generally exhibit a range of sizes resulting in a broad distribution of pore sizes within a mass of nits, with large pores between the nits and smaller pores within the nits. This pore size distribution can permit good intake of viscoelastic materials such as mucous and menses and can provide good intake of rapid gushes of fluid, while still providing the small pores needed for good
- nits and other free-flowing particles provide many pores with effective sizes on the order of the particle size, which generally is greater than the upper limits of pore size encountered in airlaids, fluff pulp, or tissue.
- Papermaking fibers include all known cellulosic fibers or fiber mixes comprising cellulosic fibers. Fibers suitable for making the webs of this invention
- 260 comprise any natural or synthetic cellulosic fibers from biological sources including, but not limited to nonwoody fibers, such as cotton, abaca, kenaf, sabai grass, flax, esparto grass, straw, jute hemp, bagasse, milkweed floss fibers, and pineapple leaf fibers; bacteria capable of producing cellulose; lyocell, rayon, or other men-made cellulose fibers; and woody fibers such as those obtained from deciduous and coniferous trees, including
- Woody fibers can be prepared in high-yield or low-yield forms and can be pulped in any known method, including kraft, sulfite, high- yield pulping methods and other known pulping methods.
- the nits comprise cellulosic fibers from two or more distinct biological sources, such as hardwood
- fibers from each source can be present at a level of 10% or greater based on mass of the fibers, or 20% or greater, or 30% or greater.
- Fibers prepared from organosolv pulping methods can also be used, including the fibers and methods disclosed in US Patent No. 4,793,898, issued Dec. 27, 1988 to
- Useful fibers can also be produced by anthraquinone pulping, exemplified by US Patent No. 5,595,628, issued Jan. 21 , 1997 to Gordon et al. In embodiments with bleached papermaking fibers, any known bleaching method can be used. Synthetically prepared cellulose fiber can also be used, including rayon in all
- Fibers 280 its varieties and other fibers derived from viscose or chemically modified cellulose.
- Chemically treated natural cellulosic fibers can be used such as mercerized pulps, chemically stiffened or crosslinked fibers, or sulfonated fibers.
- the fibers are largely unrefined or only lightly refined (e.g., less than 3 hp-days/ton of fiber of applied refining energy). Either recycled fibers or virgin fibers or both can be used, but in
- the fibers consist essentially of virgin fibers. Mercerized fibers, regenerated cellulosic fibers, cellulose produced by microbes, rayon, and other cellulosic material or cellulosic derivatives can be used. Suitable papermaking fibers can also include recycled fibers, virgin fibers, or mixes thereof.
- polymeric web refers to a porous or nonporous layer
- polymeric material can be a nonwoven web, a plastic film, a polymeric film, an apertured film, or a layer of foam.
- Polymeric webs can be used as wicking barriers, baffle layers, backsheets, and, if sufficiently liquid pervious, as topsheets of absorbent articles.
- a polymeric web can consist of about 50 weight percent or more polymeric material, more specifically about 80 weight percent or more polymeric material,
- polymeric material 295 and most specifically about 90 weight percent or more polymeric material.
- exemplary materials include polyolefins, polyesters, polyvinyl compounds, and polyamides, and copolymers or mixtures thereof.
- additives and compounds can be added to the polymeric web or be part of the polymeric components, including anti-bacterial agents, odor-control additives, mineral filler particles, surfactants, pigments and dyes, emollients,
- the web may also be treated to have electrets for improved retention of certain particles or components of body fluids.
- sanitary napkin refers to an article which is worn by females adjacent to the pudendal region that is intended to absorb and contain the various exudates which are discharged from the body (e.g., blood, menses, and urine).
- sanitary napkin While the present invention is shown and described in the form of a sanitary napkin, it should be understood that the present invention is also applicable to other feminine hygiene or catamenial pads such as pantiliners or tampons, or other absorbent articles such as diapers or incontinence pads.
- pantiliners or tampons or other absorbent articles such as diapers or incontinence pads.
- sanitary napkin is synonymous with sanitary napkin.
- the term "surfactant” includes a single surfactant or a mixture of two or more surfactants. If a mixture of two or more surfactants is employed, the surfactants may be selected from the same or different classes, provided only that the surfactants present in the mixture are compatible with each other. In general, the surfactant can be any surfactant known in the art, including anionic, cationic, nonionic and
- amphoteric surfactants examples include, among others, linear and branched-chain sodium alkylbenzenesulfonates; linear and branched-chain alkyl sulfates; linear and branched-chain alkyl ethoxy sulfates; and silicone phosphate esters, silicone sulfates, and silicone carboxylates such as those manufactured by Lambent Technologies, located in Norcross, Georgia.
- Cationic surfactants include, by way of
- nonionic surfactants include, again by way of illustration only, alkyl polyethoxylates; polyethoxylated alkylphenols; fatty acid ethanol amides; dimethicone copolyol esters, dimethiconol esters, and dimethicone copolyols such as those manufactured by Lambent
- amphoteric surfactants are the silicone amphoterics manufactured by Lambent Technologies (Norcross, Georgia).
- water retention value is a measure that can be used to characterize some fibers useful for purposes of this invention. WRV is measured by
- Fibers useful for purposes of this invention can have a WRV of about 0.7 or greater, more
- High yield pulp fibers typically have a WRV of about 1 or greater.
- a material will be considered to be "water soluble” when it substantially dissolves in excess water to form a solution, thereby losing its initial form and becoming essentially molecularly dispersed throughout the water solution.
- a water-soluble material will be free from a substantial degree of crosslinking, as crosslinking tends to render a material water insoluble.
- a material that is "water insoluble” is one that is not water soluble according to the above definition.
- Compressed materials in the present invention may be bonded with water soluble materials to permit expansion upon wetting. Water soluble adhesives may be used to join components in the present
- Adhesives and absorbent components may also be water soluble in some embodiments.
- wet strength agents are materials used to protect, strengthen, or immobilize the bonds between fibers in the wet state.
- the means by which fibers are held together in paper and tissue products involve hydrogen bonds and sometimes 350 combinations of hydrogen bonds and covalent and/or ionic bonds.
- wet strength additives are used to immobilize the fiber-to-fiber bond points and make them resistant to disruption in the wet state.
- wet state refers to a condition when the product is largely saturated with water or other aqueous solutions, but could also mean significant saturation with water-
- body fluids such as urine, blood, mucus, menses, runny bowel movement, lymph and other body exudates.
- wet strength agents materials commonly used in the paper industry to impart wet strength to paper and board that are applicable to this invention. These materials are known in the art as "wet strength agents" and are commercially available from a wide
- any material that when added to a paper web or sheet results in providing the sheet with a mean wet geometric tensile strength:dry geometric tensile strength ratio in excess of 0.1 will, for purposes of this invention, be termed a wet strength agent.
- Suitable permanent wet strength agents are typically water soluble, cationic
- polyethylenimine resins are also suitable for immobilizing the bond points in the products of this invention.
- Another class of permanent-type wet strength agents are exemplified by the aminoplast resins obtained by
- the Intake and Rewet test indicates the absorption time to intake 2 ml of synthetic menses simulant.
- This test method is adapted for nits or other free-flowing particles in an elliptical-shaped nonwoven encasement having a major axis of 9.5 cm and a minor axis of 4 cm, comprising 3.0 grams of the dry granular material to be tested and a small quantity of superabsorbent particles underneath the granular absorbent material.
- the elliptical pouch has a lower surface comprising a 20-gsm SMS (spunbond- meltblown-spunbond laminate) web produced by Corovin GMBH, Germany, treated with 15 gsm of Finley adhesive 2525A on the surface to be in contact with particles.
- This 20- gsm web is placed over a die element comprising a flat plate with an oval hole in it 9.5 cm long by 4 cm wide, with a depth of 9 mm. The 9-mm deep walls of the void in the die element are vertical. The web sags into the hole. Then 0.5 g of microcrystalline cellulose- coated superabsorbent particles are spread onto the adhesive of the web in the region over the oval hole of the underlying plate.
- the coated superabsorbent particles are prepared from Stockhausen 880 superabsorbent particles (Stockhausen Inc., Greenboro, South Carolina) treated with cellulose powder type XL110 from Functional Foods, according to commonly owned copending application Ser. No. 60/129744, "Superabsorbent-containing Composites," filed April 16, 1999, herein incorporated by reference. Afterwards, 3.0 grams of dry nits are spread over the superabsorbent particles such that the depth of the nits over the 20-gsm SMS layer is substantially uniform in the hole of the underlying plate.
- the beds of nits and the SMS layer are covered with a 40- gsm spunbond bicomponent (polyethylene/ polypropylene) web available as Prism 12T from Kimberly-Clark Corp. (Neenah, Wisconsin).
- the lower SMS and upper bicomponent webs are then heat sealed by bringing a heated element into contact with the periphery of the SMS web around the oval hole in the underiying plate.
- the two webs are thus thermally joined together to define an oval-shaped pouch comprising nits and superabsorbent particles.
- the pouch is about 6 mm to about 9 mm thick.
- the pouch is placed on an hourglass-shaped coform layer 210 mm long and 65 mm wide, consisting essentially of 60 percent polypropylene and 40 percent bleached kraft softwood fibers.
- the coform is adhesively attached to a 20-micron thick polyethylene web serving as a backsheet.
- a 20-gsm spunbond cover was placed on top of the pouch and coform layer.
- the cover stock was attached to the coform and the backsheet with adhesive, and the article was die cut to the same width and length as the coform to form a sanitary napkin.
- a two millimeter edge seal was embossed within the coform and was two millimeters from the edge of the coform.
- the pouch of absorbent particles is insulted with 2 ml of processed swine blood
- the block has a mass of 162 g and has a footprint (the contact area against the sample)
- the slot is oriented with the longitudinal direction of the pouch and placed over the longitudinal centerline thereof.
- the surface of the block rests flat on the surface of the absorbent material, such that intake of fluid occurs substantially over the area of the slot adjacent the pouch of absorbent material.
- the time to absorb 2 ml of fluid is measured in
- Timing begins when the 2 ml of fluid enters the slot and contacts the absorbent material, and timing stops when the fluid has completely passed into the cover or upper surface of the absorbent material.
- a lower absorption time is an indication of faster intake rate for the particular material.
- the initial weight of the blotter is subtracted, yielding the amount of menstrual fluid absorbed by the blotter paper in grams. Higher values are an indication of a greater degree of rewet for the particular material tested.
- the Method for Determining Centrifuge Retention Capacity measures the amount of test fluid that a sample of absorbent material retains after a centrifugal force has been applied. The amount of fluid retained is calculated as a gram per gram retention. The test is typically conducted under TAPPI Standard Conditions.
- testing according to this method is performed by placing a 0.5 g sample
- the steps of the testing method are as follows:
- a modified cylinder containing the sample of absorbent material is placed into the 50 ml Pyrex beaker.
- step 4 the timer is set for 60 minutes and started.
- the modified cylinders are removed from the Pyrex beakers and placed on the stainless steel screen for 60 seconds.
- the modified cylinders are removed from the stainless steel screen and placed in the 200 ml centrifuge bottles.
- the free-flowing particles of the present invention can have a Centrifuge Retention Capacity of at least 1.5 g/g, specifically at least 2 g/g, and most specifically about 2.2 g or greater.
- the Raw Material Absorbency Rate and Rewet Test Method 520 measures at least the following two characteristics of absorbent materials: 1. Absorbency rate - the amount of time, in seconds, it takes for a known amount of absorbent material to absorb multiple insults of known quantities of a fluid; and
- the 535 tester then waits 60 seconds from absorption of the third insult before placing a preweighed blotter paper onto the 10 ml of absorbent material and applying a 0.5 psi pressure for 60 seconds. After 60 seconds, the blotter paper is reweighed and the fluid, in grams, that has been absorbed by the blotter paper is considered the amount of rewet. Testing is typically conducted under TAPPI Standard Conditions.
- the fluid in this instance is an artificial menses (simulant), disclosed in U.S. Patent No. 5,883,231 ,
- Stopwatch readable to 0.1 s (Note: stopwatch should be NIST traceable).
- the simulant is removed from a refrigeration unit, placed on a rotator and then gently rotated for 30 minutes to thoroughly mix the contents and bring the simulant to room temperature.
- the graduated cylinder is placed onto the balance and the weight tared. 10 ml of absorbent material is introduced into the graduated cylinder. The graduated cylinder is removed from the balance. The bottom of the graduated cylinder is gently tapped on the top of the lab bench or similar hardened surface 10 times to induce settling. Visual inspection is made to ensure that there is 10 ml of absorbent material in the graduated
- the Harvard Syringe Pump is set to the Program Mode.
- the Infuse Rate is set to 250 ml/hr. with the Target Volume set to 2 ml. Diameter is set to the correct syringe size.
- the Harvard Syringe Pump is filled with 60 ml of simulant.
- the acrylic plate is placed over a weighing boat containing 10 ml of absorbent material.
- the Tygon tubing should be centered over the center of the absorbent material.
- step 9 At the end of the 60 seconds noted in step 9, gently place the 0.5 psi weight 615 onto the blotter paper and start the stopwatch.
- Steps 3 through 12 outlined above are repeated until the simulant is no longer absorbed by the absorbent material (i.e., the simulant sits on the top of the absorbent 620 material and is not absorbed within five minutes).
- angle of repose refers to the angle relative to the horizontal plane formed by the sides of a pile of free flowing particles prepared under controlled circumstances. Generally, a low angle of repose is indicative of the ability to flow readily, while a high angle of repose suggests that particulates do not flow well or tend to adhere. A measurement for angle of repose suited for the free-flowing particles of the present
- FIG. 9 depicts an apparatus 100 intended to permit measurement of the angle of repose of a pile of particles formed on a cylindrical platform 110.
- the apparatus comprises a powder funnel 102 (a Nalgene® 80 mm plastic funnel, Catalog No. 30252-955 in the VWR Scientific Products Catalog) having a height of 106 mm (the distance from the top of the funnel to the top of the stem 108).
- the powder funnel 102 has an upper opening 104 that is 104 mm wide.
- the lower stem 108 that has an outer diameter of 21 mm, a length of 33 mm, and is provided with a lower opening 106.
- Particles placed in the funnel fall to the brass cylinder 110 having a diameter D of 15.2 cm.
- the edges are free of burrs or other nonuniformities that would prevent particles from falling off the cylinder.
- the cylinder 110 is axially centered with the axis of
- the funnel 102 resides a distance L of 15 cm below the lower opening 106 of the funnel 102.
- the cylinder 110 has a height great enough to permit particles to spill to the side without rising from the underlying platform to reach the level of the upper surface of the cylinder 110. A height of at least 5 cm is recommended.
- the powder funnel 102 is held with a ringstand. Both the funnel 102 and the cylindrical
- 660 and higher relative humidities can be used to further elevate moisture content.
- moisture contents above about 10% it may be necessary to apply a fine mist of deionized water to the nits as they are stirred and to allow 15 minutes for a uniform redistribution of moisture within the nits. Once moistened, the nits are again measured for angle of repose. If particles begin to bridge and cease flowing freely from the funnel, gentle tapping
- 665 may be performed by gently striking the outer surface of the funnel three times at three uniformly spaced locations about the diameter of the funnel 102 at a height of 10 cm above the lower outlet 106, spaced apart by about 0.5 seconds. Striking is performed with only enough force to dislodge the particles. If bridging continues to be a problem, the particles can be slowly trickled into the funnel 102 to allow them to fall through the stem
- Nits without debonder and nits with a substantial amount of loose fibers projecting from the surface of the nits will often have an angle of repose as high as about 70 degrees when dry, but can still be useful in the present invention.
- free-flowing particles useful in the present invention can have an
- angle of repose while dry of about 60 degrees or less, more specifically about 55 degrees of less, and most specifically about 47 degrees or less, with exemplary ranges of from 10 to 45 degrees or from about 25 degrees to about 38 degrees.
- the particles will still have an angle of repose less than about 75 degrees and can still be
- the angle of repose can increase by no more than 15 degrees, specifically no more than 10 degrees, and most specifically no more than 6 degrees, as moisture content is increased from 5% to 100%.
- apparatus 420 consists of a cylinder 422 and a piston generally indicated as 424.
- piston 424 consists of a cylindrical LEXAN® shaft 426 having a concentric cyiindrical hole 428 bored down the longitudinal axis of the shaft. Both ends of shaft 426 are machined to provide ends 430 and 432.
- a weight, indicated as 434, rests on end 430 and has a cylindrical 690 hole 436 bored through the center thereof. Inserted on the other end 432 is a circular piston head 440.
- Piston head 440 is sized so as to vertically move inside cylinder 422. As shown in FIG. 12, piston head 440 is provided with inner and outer concentric rings containing seven and fourteen 0.95 cm (0.375 inch) cylindrical holes, respectively, indicated generally by arrows 442 and 444. The holes in each of these concentric rings
- Piston head 440 also has cylindrical hole 446 bored in the center thereof to receive end 432 of shaft 426.
- Attached to the bottom end of cylinder 422 is a No. 400 mesh stainless steel cloth screen 448 that is biaxially stretched to tautness prior to attachment.
- Attached to the bottom end of piston head 440 is a No. 400 mesh stainless steel cloth screen 450 that is
- a sample of absorbent material indicated as 452 is supported on screen 448.
- Piston head 440 is machined from a LEXAN® rod. It has a height of 0.625
- End 430 is 2.54 cm (1 inch) long and 1.58 cm (0.623 inches) in diameter, forming an annular shoulder to support the stainless steel weight 434.
- the annular stainless steel weight 434 has an inner diameter of 1.59 cm (0.625 inches), so that it slips onto end 430 of shaft 426 and rests on the annular shoulder formed therein. The combined weight of piston 424 and weight 434
- the cylinder 422 When solutions flow through the piston/cylinder apparatus, the cylinder 422 generally rests on a 16-mesh, rigid stainless-steel support screen (not shown) or equivalent.
- the piston and weight are placed in an empty cylinder to obtain a measurement from the bottom of the weight to the top of the cylinder. This measurement is taken using a caliper readable to 0.01 mm. This measurement will later be used to calculate the height of the gel bed. It is important to measure each cylinder empty and keep track of which piston and weight were used. The same piston and weight should be used for
- the adsorbent layer used for GBP measurements is formed by swelling 3.0 g of a absorbent material in the GBP cylinder apparatus (dry polymer should be spread evenly over the screen of the cylinder prior to swelling) with 0.9% (w/v) aqueous NaCl for a time period of 15 minutes.
- the sample is taken from a population of absorbent material that is
- the absorbent material therefore, has a particle size of between 300 and 600 microns.
- the particles may be prescreened by hand or automatically prescreened with, for example, a Ro-Tap Mechanical Sieve Shaker Model B, commercially available from W. S. Tyler, Inc., Mentor, OH USA.
- the cylinder is removed from the fluid and piston weight assembly is placed on the gel layer.
- the thickness of the swollen layer is determined by measuring from the bottom of the weight to top of the cylinder with a micrometer. The value obtained when taking this measurement with the empty cylinder is subtracted from the value obtained after swelling the gel. The resulting value is the height of the gel bed
- the GBP measurement is initiated by adding the NaCl solution to cylinder 422 until the solution attains a height of 4.0 cm above the bottom of the gel layer 452. This solution height is maintained throughout the test.
- the quantity of fluid passing through the gel layer 452 versus time is measured gravimetrically. Data points are collected every
- K [Q * (H * Mu)]/[A * Rho*P]
- K Gel Bed Permeability (cm 2 );
- Q flow rate (g/sec);
- A cross-sectional area for liquid flow (cm 2 );
- Rho liquid density (g/cm 3 );
- P hydrostatic pressure (dynes/cm 2 ) (normally 3923 dynes/cm 2 ).
- AUL Absorbency Under Load
- DAT Demand Absorbency Tester
- a level porous plate is used having ports confined within a 2.5 cm. diameter area to provide liquid saline solution, 0.9 (w/w)% sodium chloride, delivered from a reservoir to the porous plate such that there is no hydraulic head (neither positive pressure nor suction) at the top of the porous plate.
- liquid saline solution 0.9 (w/w)% sodium chloride
- a 4.4 g piston (“spacer disk”) is made from 2.54 cm (one inch) diameter solid material (e.g., a clear plastic) and is machined to closely fit
- a standard 100 gm weight placed on the piston is used to provide a 21 ,000 dyne/sq.cm. (about 0.3 psi) restraining load which is commonly experienced in infant diapers.
- a material sample is cut into circular discs with a diameter slightly smaller than 2.54 cm (one inch) to freely fit within the sample tube.
- 785 sample mass should be from about 0.05 g to about 0.16 g.
- This test is initiated by placing a 3 cm diameter GF/A glass filter paper onto the porous plate (the paper is sized to be larger than the inner diameter and smaller than the outer diameter of the cylinder), to insure good contact while eliminating evaporation over the ports of the DAT and then allowing saturation to occur.
- the material to be tested is
- the AUL apparatus is placed on the glass filter paper. The amount of fluid pick-up is monitored as a function of time
- the amount of fluid pickup measured after one hour is the AUL value, expressed as grams of liquid per dry gram of the tested material.
- the AUL of the materials of the present invention can be above 6 grams/gram, more specifically about 10 grams/gram or greater, still more specifically about
- AUL values can be achieved without the addition of superabsorbent material or swellable binder material, especially high values of AUL are possible through incorporation of superabsorbent material into the absorbent structure.
- Free Swell Capacity is the result of a test which measures the amount in grams of an aqueous solution, containing 0.9 weight percent sodium chloride, that a gram of a material can absorb in 1 hour under negligible applied load. The test is done as described above for the AUL test, except that the 100 gm weight is not placed on the sample.
- the Free Swell Capacity of the materials of the present invention can be above 8, more specifically above 10, more specifically above 20, and most specifically above 30 grams/gram.
- Free Swel AUL Ratio is the ratio of Free Swell Capacity to AUL. It will generally be greater than one. The higher the value, the more sensitive the material is to compressive load, meaning that the sample is less able to maintain its potential pore volume and capillary suction potential under load.
- the materials of the present invention have "Free SwelLAUL Ratio" of about 4 or less, more specifically about 2 or less, more specifically still about 1.5 or less, and more specifically about 1.3 or less, with an exemplary range of from about 1.2 to about 2.5.
- Moist fibers are first provided, typically at an elevated consistency typically greater than 10% and more specifically at about 20% or higher and most specifically at about 30% or higher, with an exemplary range of 32% to about 55%. Any papermaking fibers can be used, as well as other
- hardwood fibers are the primary fibrous component of the nits.
- short papermaking fibers are used for the production of nits, wherein the fibers have a weight-average length of less than 3.5 mm, specifically less than about 2 mm, and more specifically from about 0.2 mm to about 1.7 mm based on fiber length measurement with
- Providing the fibers at elevated consistency can require a dewatering step to make dilute fiber suspensions more concentrated.
- a low-consistency slurry can be dewatered in a belt press.
- the belt press can be any suitable commercially-available unit, such as a Belt Filter Press from Komline Sanderson (Peapack, NJ). Depending on the
- the filter cake typically can have from 25-45% solids, more specifically 30 to 45% solids and most specifically 35-40% solids.
- shaft disperger can be used capable of applying high-shear to pulp.
- High-shear treatment can last for about one minute or more (i.e., the average retention time of fibers passing through the device can be about one minute or greater).
- Examples of specific devices suitable for disperging include the BIVIS machine (commercially available from Clextral Company, Firminy Cedex, France) and the Maule shaft disperger such as Maule Type GR 865 11 manufactured by Ing. S. Maule & C. S.p.A., Torino, Italy, illustrated and described in detail in US Patent No. 5,772,845, "Soft Tissue,” issued June 30, 1998 to Farrington, Jr. et al., herein incorporated by reference.
- Disk dispersion or disperging
- a heating unit such as a heated screw
- an additional disperging step may be needed to create suitable nits.
- Kneaders (regarded as a specific form of disperger as used herein) usually operate at lower temperatures, such as about 40°C to 70°C, and are available in single and double shaft designs with rotational speeds of 200 to 1000 rpm. Retention time in the
- 885 kneading zone is long compared to disk dispersion and can be effective in imparting curl or entanglement.
- a kneader is the Voith Sulzer KD-500 kneading disperger (so termed in the above-referenced article of Hostetter - kneading can be considered as one form of disperging for the purposes of the present invention).
- the Ahlstrom MDR® Kneader can also be used.
- Another example of a kneader is provided in
- Kneaders are generally operated at power levels similar to those of disk dispergers or other dispergers, but can be operated at higher power levels for purposes of the present invention.
- nit formation is to be promoted by operation, for example, at one or more of elevated energy levels, elevated dwell times (tied to throughput), and elevated consistencies. For a given device, simple optimization
- 900 of energy, throughput, and consistency can be applied to maximize nit production. Further, applied power, throughput rates, and temperature can be optimized for a given furnish to achieve the desired particle density, absorbent capacity, and size distribution. Chemical additives (nit conditioners) can also play a useful but optional role, as described below. In one embodiment, energy levels above the typical levels of commercial disperger
- energy levels above 90 kilowatt-hours/ton can be applied. More specifically, energy levels for disperging of fibers can be any of the following ranges: about 95 kwh/t or greater, about 140 kwh/t or greater, about 200 kwh/t or greater, from about 95 kwh/ton to about 600 kwh/t, and from about 110 kwh/ton to about 300 kwh/ton.
- BIVIS disperger consistencies greater than 50% can be utilized without plugging.
- This device can be generally described as a pressurized twin screw shaft disperger, each shaft having several screw flights oriented in the direction of material flow followed by several flights oriented in the opposite direction to create back pressure. The screw flights are notched to permit the material to pass through the notches from one
- the temperature of the fibrous suspension entering the disperger can be about 20°C or greater, specifically about 50°C or greater, more specifically about 70°C or
- Disperging (generally synonymous with “dispersing” or “dispersion” in the art of mechanical treatment of papermaking fibers) will elevate the temperature, depending on the energy input.
- the temperature of the pulp immediately after dispersion can be about 50°C or higher, more specifically about 80°C or higher, with an exemplary range of 90°C to 130°C and more specifically from about
- the outlet consistency from the disperger can be from about 20% to about 75%, specifically from about 40% to about 60% and more specifically from about 45% to about 55%. Good results have been obtained with specific
- nit conditioners or, more generally, “particle conditioners”
- a debonder such as a lubricant, a wax, a silicone compound, or other
- nit conditioners or particle conditioners can improve the free flowing properties of the particles.
- conditioners and other chemicals can be added at any suitable time during preparation and treatment of the particles.
- nit conditioners can be any suitable time during preparation and treatment of the particles.
- nit conditioners and other chemicals can be injected into any one of several zones in the disperger itself or added to the nits after formation, such as before, during, or after drying. Also, chemical addition during or after nit drying
- 955 can be selectively onto the surface of the surface and can efficiently modify particle- particle interactions.
- benefits in nit properties can also be achieved by adding known surfactants or dispersants during the processing of the nits.
- surfactants or dispersants such as Triton X-100, when present during a disperging operation, can modify the surface
- debonders on the surface of a fibrous nit can prevent bonding or clumping between nits and can enhance the lubricity of the nits relative to one another.
- debonder selectively
- debonder increases the lubricity of fibers during a disperging process and allows floes to be broken up into smaller sized bundles.
- a process that might result in a mean particle size of about 1 mm without debonder might yield a mean particle size of about 0.6 mm with 0.5% to 2% debonder present (weight percentage based on dry fiber mass).
- Application of the debonding agent can therefore be done in either or both of two ways: (1 ) applying a debonder to the fibers or fiber slurry prior to or during disperging to control formation of nits and nit size, and (2) applying a debonder (or other hydrophobic material or compound comprising fatty moieties) to the surface of at least a portion of the nits after the nits have been formed by mechanical processes and before, after, or during
- Suitable debonders can include any number of quaternary ammonium compounds and other softeners known in the art, including Berocell 596 and 584 (quaternary 1005 ammonium compounds) manufactured by Eka Nobel Inc., which are believed to be made in accordance with US Pat. Nos. 3,972,855 and 4,144,122; Adogen 442 (dimethyl dihydrogenated tallow ammonium chloride) manufactured by Sherex Chemical Company; Quasoft 203 (quaternary ammonium salt) manufactured by Quaker Chemical Company; and Arquad 2HT75 (di(hydrogenated tallow) dimethyl ammonium chloride) manufactured
- Softening agents known in the art of tissue making can also serve as debonders or hydrophobic matter suitable for the present invention and can include, without limitation, fatty acids, waxes, quaternary ammonium salts, dimethyl dihydrogenated tallow ammonium chloride, quaternary ammonium methyl sulfate, carboxylated polyethylene, cocamide diethanol amine, coco betaine, sodium lauroyl
- Anti-static agents typically have side chains similar to those of useful debonders and can be present as well. In some cases, anti-static compounds are helpful in reducing
- Silicone compounds can be useful in providing nits with certain properties, especially in terms of resisting clumping when wet and in providing useful tactile and free flowing properties when dry.
- Useful silicone compounds include silicone-based
- silicone compounds include silicone quats such as silicone alkylamido
- silicone esters including phosphate esters which can provide lubricity
- dimethiconol stearate and dimethicone copolyol isostearate which is highly lubricious and can be applied as microemulsion in water
- silicone copolymers with polyacrylate, polyacrylamide, or polysulfonic acid silicone iethioniates;
- Hydrophilic debonders may be applied at the same doses and in a similar manner as hydrophobic debonders.
- Surfactants can be anionic, cationic, or nonionic, and can include any known in the art that are not incompatible with the health and property requirements of the present invention.
- additives may be applied to achieve a variety of useful purposes, with application of such additives occurring before, after, or in combination with application of nit conditioners, or without the application of nit conditioners at all.
- Such additives can be applied by spray, by contact with a wetted surface, by trickling of a stream into a mixed bed of particles, and the like.
- the additives may be applied uniformly or nonuniformly to the surface of treated particles, and all or suitable only a portion of the particles may be treated. In one embodiment, from 5% to 90% of the particles are treated, specifically from about 10% to 70%, more specifically from 10% to 50%, and most specifically from about 10% to about 30% of the particles are treated.
- nits are disperged with added ammonium zirconium carbonate, such as 0.3 to 3 weight percent based on dry fiber mass, followed by treatment at elevated temperature (greater than 100 °C), optionally in a fluidized bed or high shear air drier, to crosslink the fibers inside the nits but not between the nits, maintaining a loose bulk structure in the dried product.
- Ammonium zirconium carbonate can act as a
- the 1070 crosslinker can impart lubricity, promoting a free-flow behavior in the nits and optionally contributing to useful tactile properties.
- Minerals and fillers such as clays and zeolites may also be added to the fibers in making nits, for odor control, absorbency control, anti-microbial control, or other purposes.
- the nits are treated with both a debonder and crosslinking
- the debonding agent or surfactant is added to the pulp prior to the addition of the latent crosslinking agent.
- the latent crosslinking agent can be added to cellulose while it is at a moisture content greater than about 10%, more specifically greater than about 30%. Crosslinking is substantially completed during subsequent drying
- the latent crosslinking agent may be selected from any of the following well known materials which serve this function.
- Useful types can be selected from urea derivatives such as methylolated urea, methylolated cyclic ureas, methylolated lower alkyl substituted cyclic ureas, dihydroxy cyclic ureas, lower alkyl substituted dihydroxy cyclic ureas,
- a useful latent crosslinking material is dimethyloldihydroxyethyleneurea (DMDHEU, 1 ,3-dihydroxymethyl- 4,5-dihydroxy-2-imidazolidinone). This material is readily commercially available in a stable form.
- DMDHEU dimethyloldihydroxyethyleneurea
- DMU dimethylol urea
- DHEU dihydroxethyleneurea
- DMEU dimethylolethylene area
- DAI 4,5-dihydroxy-1 ,3-dimethyl-2-imidazolidinone
- latent crosslinking agents based on urea In addition to those latent crosslinking agents based on urea, other materials that are suitable are polycarboxylic organic acids, including 1 ,2,3,4-butanetetracarboxylic acid.
- a neutral or acidic catalyst may be included with the latent crosslinking agent to increase the reaction rate between the crosslinker and the cellulose.
- Acidic salts are particularly useful as catalysts when the urea-based materials are employed. These salts may typically be ammonium chloride or sulfate, aluminum chloride, magnesium chloride or mixtures of these or many other similar materials.
- Alkali metal salts of phosphorous- 1110 containing acids, such as sodium hexametaphosphate and sodium hypophosphite, with or without additional oxalic acid, are useful catalysts for 1,2,3,4-butane carboxylic acid.
- the crosslinking agent is typically present in an amount in the range of about 0.1% to about 15% (weight percent based on the mass of dry fiber), specifically from about 0.3% to about 6%, and more specifically from about 0.5% to about 3%. Similarly, the crosslinking agent is typically present in an amount in the range of about 0.1% to about 15% (weight percent based on the mass of dry fiber), specifically from about 0.3% to about 6%, and more specifically from about 0.5% to about 3%. Similarly, the
- 1115 debonding agent is generally present in an amount of about 0.1% to about 10% (weight percent based on the mass of dry fiber), specifically from about 0.3% to about 4%, and more specifically from about 0.5% to about 2%. Generally, there will be no need for washing of the pulp after the crosslinking reaction is completed.
- the nits can be combined with other agents in a pouch of an absorbent article to
- 1120 further increase the absorbent capacity of the pouch or to control fluid the handling performance or macroscopic mechanical or rheological properties of the contents of the pouch.
- Materials capable of providing additional absorbent capacity include superabsorbent particles, particularly superabsorbents adapted for intake of menses, cellulose fibers, superabsorbent fibers and films, and one or more layers of a
- the nits can also comprise a percentage of inorganic material or minerals such as clays (e.g., kaolin clay, bentonite, etc.), calcium carbonate, zeolites, vermiculite, titanium dioxide, mica, talc, alumina, silica, sodium bicarbonate, and the like.
- clays e.g., kaolin clay, bentonite, etc.
- calcium carbonate zeolites
- vermiculite titanium dioxide
- mica mica
- talc alumina
- silica sodium bicarbonate
- Other additives can be applied for specific purposes, such as odor control agents, ion exchange resins, anti-microbials, chitosan and chitin particles or additives, enzymes,
- Add-on levels can be varied to achieve the desired objectives, but by way of example can be selected from any of the following ranges for weight percents based on dry fibers: from 1% to 50%, from 2% to 10%, from 1 %-5%, less than 10%, less than about 5%, less than 2%, from about 0.2% to about 3%, and substantially 0%.
- known cationic retention aids are added to the pulp fibers prior to nit formation (prior to or at the beginning of disperging) to promote and control fioc formulation, particularly in dilute suspensions of papermaking fibers (e.g., consistency less than about 8% or less than about 4%).
- Retention aids known in papermaking include a variety of cationic polymers such as polyacrylamides, cationic starch, modified guar gum,
- 1140 or dual-component retention aid systems can be useful in controlling the size of nits formed from a papermaking slurry of wood fibers.
- Related principles are discussed by S. Main and P. Simonson in "Retention Aids for High-speed Paper Machines," Tappi Journal, Vol. 82, No. 4, pp. 78-84, herein incorporated by reference.
- 1145 For polymethyl urea spheres or for free-flowing particles in general, Vermiculite and clay particles can be present, particularly when other more regular shaped particles are present to enhance flowability. For example, if about 20% or more, specifically about 30% or more and more specifically about 40% or more of the volume of the particulate matter is occupied by substantially spherical or ovoid free-flowing particles, non-spherical
- 1150 particles such as vermiculite or clays can be present while still permitting desirable rheological properties to be maintained.
- clays or vermiculite can be present without suffering from the rheological disadvantages presented by the pure minerals.
- the nits After disperging, the nits generally require input of further energy to dry them, as shown in FIG. 1.
- the nits, once dried, are substantially free of clumps of multiple nits.
- some form of agitation during drying can be useful. Agitation after drying to break apart clumps can also be practiced.
- a high-shear air dryer or fluidized bed dryer can be used, wherein jets of heated air rising from beneath the nits in a tank, drum, rotary dryer, or bed stir and agitate the nits and help maintain them in a loosened state.
- jets of air adjacent the exit port of the disperger immediately break up the nits and cause both
- nits may be dumped, conveyed, or pneumatically blown into rotating drums or tumblers which permit passage of heated gases into the nits.
- Rotating dryer units especially those with stirring means or spoiler bars are also useful, for the mechanical stirring or motion of the dryer helps prevent clumping of the nits as they dry and helps in drying the nits uniformly.
- the dryers to further agitate the particles can be helpful.
- Any number of commercial particle dryers, fluidized beds systems, and high shear dryers can be adapted to the purpose of drying nits, using principles well known to those skilled in the art. Examples include particle processing equipment of Carman Industries, Inc., including Carman® Fluid Bed Processors such as the Model FBP-1322, Adjust-A-FlowTM Vibrating Feeders,
- fluidized bed dryers are the fluid bed dryers of Swenson Process Equipment (15700 Lathrop Avenue Harvey, Illinois 60426), or the Swenson rotary dryers and flash dryers.
- Other examples of useful dryer means include the "plow dryer” of Processall, Inc.,
- This device comprises a vessel with a shaft having a series of rotating elements (plows), designed to lift and separate the product inside the vessel. The design of the blades, the number and spacing of the elements, and the speed all
- the fibers will generally have become entangled into small, dense bundles (nits).
- the nits can have a mean particle size of about 50 micrometers to about 1000
- nits 1200 and more specifically less than 5% by weight of the nits have a particle size greater than 2 mm or a size less than 50 micrometers. More specifically, less than 5% by weight of the nits have a particle size greater than 1 mm. Most specifically, less than 1 % by weight of the nits have a particle size greater than 1 mm. Alternatively, at least 90% by weight and or, more specifically, at least 95% by weight of the dry nits or dry free-flowing particles
- a particle size as determined by sieve analysis (e.g., ASTM method D-1921 ), of any one of the following ranges: from 100 micrometers to 850 micrometers, from 100 micrometers to 800 micrometers, from 300 micrometers to 850 micrometers, from 300 micrometers to 600 micrometers. It is understood that the particles measured by sieve analysis may comprise cohesive agglomerates of smaller particles.
- Methods of manufacturing the nits can further comprise subsequent treatments after drying such as sorting, sieving, screening, winnowing, and the like to remove the largest nits and/or to remove small fibers or other undesired particles.
- Sorting of the nits by particle size by screening, sieving, and the like can be done. Sorting or separating can also be performed by aerodynamic methods (e.g., entrainment in a fluidized bed) to 1215 remove particles with the largest effective surface area or aerodynamic drag, or to sort particles according to density. Cyclones can be effective in sorting particles entrained in air or other fluids according to the density of the particles.
- Nits can be classified by other methods such as by screening, exemplified by vibrating or gyratory screeners, such as those described by N. McCauley in “Vibrating and Gyratory Screeners: Proper Installation Yields Top Performance," in Powder and Bulk Engineering, Dec. 1999,
- sieving including ultrasonic sieving, such as with a SonoScreen® device by Telsonic Ultrasonics (Bridgeport, NJ), or gyratory sieves, such as the Vort-Siv® Model RBF-10 gyratory sieve (MM Industries, Salem, OH); air classification such as with the NSP Powderizer® by Sturtevant, Inc. (Hanover, MA) or Marsulex® Air Classifiers (Marsulex Environmental Technologies, Riverside, PA), or centrifugal air classifiers by
- classification into two or more particle sizes is performed with a Coanda-effect gas stream particle classifier as described in US Pat. No. 6,015,648, "Gas Stream Classifier and Process for Producing Toner,” issued to S. Mitsumura et al., Jan. 18, 2000, herein incorporated by reference.
- the dry nits typically have a density above the critical density of the fibers, so that
- Nits combined with hydrogel forming materials are especially likely to swell substantially upon wetting and can improve body fit through that mechanism.
- useful materials for forming free-flowing particles include polymethyl urea spheres, as disclosed in WO 98/43684, "Absorbent Item," M. Raidel, Oct. 8, 1998.
- Microporous macrobeads can also be used, such as those disclosed by A.J. Disapio et al. in "Microporous Macrobeads Provide New Opportunities in Skin 1245 Care," Soap and Cosmetics, Vol. 75, No. 2, Feb. 1999, pp. 42-47, which are palpable polymeric beads that may be spherical or formed by attrition of spheres comprising pores within the bead for retention or release of chemical agents or liquids.
- Microporous macrobeads are commonly made from acrylate copolymers with added monomers to control surface properties, void volume, etc. For example, ester-rich monomers lead to
- Particle size for macrobeads useful in the present invention can be from about 100 to 500 microns, or from about 300 to 600 microns.
- Microporous macrobeads may be used alone or in combination with nits, microspheres, beads, or PMU particles.
- Porous, hollow, or solid spheres of silica and other minerals can also be used, as well as other particle shapes adapted for free flowing performance. Particles that have
- anti-stick agents such as silicones, talc, fluorinated polymers, and the like can also provide good flowability in the dry state.
- the free-flowing particles can be absorbent but substantially non-swelling (i.e., when wetted with 50% moisture by weight, the bulk volume of the assembled particles increases by less than 20%, or at a 200% moisture uptake, the bulk volume of the
- the free-flowing particles can serve both as an effective intake means for the absorption of menses and other body fluids, and as a body-conforming means for
- the free-flowing particles can remain mobile even when wet, particularly when previously treated with at least one of lubricants, debonders, surfactants, dispersants, or hydrophobic material, and can flow in response to shear or compressive forces over a wide range of saturation values, permitting the nits to conform to the body and provide comfort.
- the kinds of particles present in an absorbent article can differ in physical properties such as particle size, surface smoothness, wetting characteristics, presence of debonder or anti-static compounds or other anti-dumping agents; density, fiber type, fuzziness or degree of fibrillation, etc.
- Other particles or agents may be added for comfort, compressibility, and
- tactile properties including small pieces of soft, deformable foam, such as regular or irregular shaped particles of foam rubber or polyurethane foam, having, by way of example, a particle size from about 300 micrometers to 2 mm, and specifically from about 400 micrometers to about 1 mm. While the foam or other added particles may not be highly free flowing or perhaps not free flowing at all by its self, when combined with a
- one or more kinds of nits can be combined with other particles such as microspheres, spherical minerals, coated particles, and the like. Incorporation into Absorbent Articles
- nits comprising papermaking fibers can serve as the absorbent material in elongated absorbent pads for absorbing oil or other spilled liquids.
- Illustrative absorbent pigs are detailed in copending patent application Ser. No. 09/119602, "An Elongated Liquid Absorbent Pad and System for Collecting Leaks and
- free-flowing particles such as eucalyptus nits or sulfite softwood nits encased in an elongated liquid pervious web such as a spunbond web can form the interior absorbent material of an elongated absorbent pig suitable for containment of oil spills and other leaks in an industrial or workplace
- the free-flowing particles allow the pig to conform to the surroundings, which are often irregular, in order to maximize leak prevention and absorption of fluids.
- the free-flowing particles of the present invention can also be of value in many absorbent articles, particularly those adapted to conform to the body of a wearer, exploiting the ability of free-flowing particles to deform and flow in response to the
- the free-flowing particles of the present invention could be used as an absorbent component in sanitary napkins (feminine care pads and related catamenial devices, including "ultra- thin" pads and pantiliners and maxipads), incontinence pads, diapers, menstrual pants, disposable briefs for children (training pants), breast pads, bed pads, sweat absorbing
- FIG. 2 depicts the cross-section along the transverse centerline of an absorbent article 20 which, in this embodiment, is a sanitary napkin having a longitudinal direction normal to the cross-section shown.
- the article 20 comprises an absorbent core 22
- the absorbent core 22 comprises a conformable intake member 30, an upper absorbent layer 32 and a lower absorbent layer 34.
- the conformable intake member 30 comprises a longitudinal pouch 36 of free-flowing particles 38 such as nits. The free-flowing particles
- the 1315 38 can be substantially free of superabsorbent particles or other powdered or granular materials other than cellulosic materials, or can be combined with superabsorbent particles or other granular materials if desired.
- the upper absorbent layer 32 is transversely wider than the lower absorbent layer 34 such that the upper absorbent layer 32 is held in
- the upper absorbent layer 32 and the lower absorbent layer 34, as well as any other absorbent components apart from the free-flowing particles 38, can independently be any porous absorbent material known to be useful in sanitary napkins or other absorbent articles, such as one or more plies of wetlaid or airlaid tissue; cellulosic airlaid webs of comminuted fibers (commonly termed "airfelt"); other dry laid and airlaid webs;
- the upper absorbent layer 32 and lower absorbent layer 34 can also comprise superabsorbent particles, fibers coated with or attached to superabsorbent particles, or other superabsorbent materials.
- the nits can comprise papermaking fibers having at least 30% hardwood fibers
- the nits can have an angle of repose of less than 72° and specifically less than about 60° in the dry state and in one embodiment, can still have angles of repose in the aforementioned ranges even at a moisture content of 50%.
- the conformable intake member 30 can be elongated in the longitudinal direction
- the width of the conformable intake member 30 can be about 2 cm or greater, or less about 5 cm or less or more specifically about 4 cm or less, while having a length of about 8 cm or greater, more specifically about 10 cm or greater, and most specifically
- the thickness of the absorbent article 20 can be from about 2 mm to about 50 mm, more specifically from about 3 mm to about 25 mm, more specifically still from about 3 mm to
- Ultrathin articles can have a thickness less than about 6 mm.
- free-flowing particles 38 can be incorporated into one or more discrete pouches 36 in the article or can be mixed together uniformly or in gradient form. Principles and equipment for mixing free-flowing particles are described by B.H. Kaye in
- the pouch 36 can be a nonwoven web or tissue web adapted to fully enclose the free-flowing particles 38. However, it need not be a single material forming a complete encasement or envelope for the particles 38, but can be formed by the interaction of a
- a pouch 36 can be formed by the interaction of a backsheet 26, an outer absorbent member 42 comprising a central void 44 for receiving free-flowing particles, and a topsheet 24, whereby attachment of the various components serves to prevent the free-flowing particles 38 from escaping the article 20.
- the absorbent article 20 comprises a pocket of substantially loose absorbent material comprising a first type of free-flowing particles 38 and a second type of particles (not shown) to obtain a balance between various properties such as ability to flow freely when dry or when wet, absorbency, conformability, ability to resist bunching, etc.
- a third type of particles (not shown) or even more types of particles can be
- the first type of particles 38 is hardwood nits, optionally comprising 50% or more of the mass of the absorbent material in the pocket.
- the second type of particles can be other cellulosic nits, such as, for example, softwood nits having a substantially larger particle size than the first type of particles.
- the second type of particles like the first type, can be treated with a small quantity (e.g., less than 5%
- the central absorbent member 46 comprises loose nits of fibrous material comprising a first type of free-flowing particles 38 and a second type of free-flowing particles, substantially distinguished in a material 1390 property selected from fiber type, mean particle size (determined by sieve analysis according to American Society for Testing and Materials (ASTM) test method D-1921), ash content, chemical additive content, Water Retention Value, and wetting angle of the surface of the particles.
- superabsorbent particles and odor control materials can be present as the second type or third type of particles or as a portion of a mix or composite
- 1400 superabsorbent or hydrogel-forming polymeric material and nits in the absorbent composition.
- less than about 10% superabsorbent particles are present for nits treated with hydrophobic material, in order to help maintain a free flowing nature of the nits even when wetted.
- nits or other free-flowing particles 38 such as hollow spheres
- deformable particles 1405 are combined with deformable particles having, by way of example only, a particle size of about 2 mm or less, more specifically about 0.7 mm or less, including pieces of a soft foam such as a polyurethane foam or foam rubber material. Rounded particles can be used.
- the soft, deformable particles combined with the can help improve the tactile properties of the filled pouch 36, allowing a softer feel and more comfort when worn
- the free flowing particles 38 for use in any of the absorbent members of the present invention can be combined with one or more deformable materials, particularly in particulate form, for improved comfort and avoidance of a grainy feel, especially when larger sized free-flowing particles are used.
- the topsheet 24 can be any material known to be useful as topsheets in absorbent
- topsheets can be made in accordance with US Pat. No. 5,533,991 , issued July 9, 1996 to Kirby et al.; US Pat. No. 4,342,314 issued Aug. 3, 1982 to Radel et al. and US Pat. No. 4,463,045 issued Jul. 31 , 1984 to Ahr et al..
- the topsheet 24 may comprise an additional transfer layer (not shown) to help direct fluid into the absorbent core 22, as disclosed, for example, in US Pat. No. 4,397,644, issued Aug. 9,
- the topsheet 24 may comprise one or more layers of microdenier fibers, such as those disclosed in European Patent Application 893,517-A2, "Micro-Denier Nonwoven Materials Made Using Modular Die Units," A. Fabbricante, et al., published Jan. 27, 1999.
- the topsheet 24 need not have uniform properties but can be preferentially more permeable or liquid pervious or wettable over the central absorbent member than it
- the backsheet 26 may be any flexible, liquid impervious material that prevents discharges collected by the absorbent article 20, such as a sanitary napkin, from escaping the article 20 and soiling the undergarments and clothing of the wearer.
- the backsheet 26 and other components may be biodegradable and/or flushable.
- a flushable article is one that can be directly discarded into a toilet and flushed without clogging piping and without harm to septic systems.
- the backsheet 26 may also be extensible or elastically deformable for use in extensible absorbent articles. Any methods known in the art for production of elastic or stretchable films or cover sheets may be used, including those disclosed in US Pat. No. 5,702,378, issued to Widlund et al., Dec. 30,
- FIG. 3 depicts an absorbent article 20 related to that of FIG. 2 and generally follows the number scheme of FIG. 2.
- the absorbent core 22 of the absorbent article 20 further comprises an outer absorbent member 42 with a central void 44 therein for receiving the lower absorbent layer 34 and the upper absorbent layer 32, which,
- the wicking barrier 48 is a section of polymeric film or other flexible, hydrophobic or liquid impervious material to help contain fluid within the central absorbent member 46 and to
- the wicking barrier 48 can be a polyolefin film, a fluid-resistant nonwoven web, a tissue treated to be hydrophobic, or the transfer delay barrier materials disclosed in the commonly owned US patent application Ser. No. 60/079,657, "An Absorbent System for Personal Care Products Having Controlled Placement of Visco-Elastic Fluids" by A.S.
- the wicking barrier 48 is optionally provided with apertures for controlled release of fluid from the central absorbent member 46 to the outer absorbent member 42. As depicted, the wicking barrier 48 has an underlying portion 50 beneath the lower absorbent layer 34, a vertical component 52 spanning a vertical distance between the outer absorbent member 42 and the central
- the wicking barrier 48 helps prevent fluid communication between the outer absorbent member 42 to the central absorbent member 46 not only by impairing lateral wicking, but by obstructing contact between the two absorbent members 42, 46 when the article 20 is worn and laterally
- the Intrinsic Absorbent Capacity of the barrier material can be about 1 or less, more specifically less than about 0.5, more specifically still less than about 0.3, and most specifically less than about 0.1.
- the material of the wicking barrier 48 can be substantially non-absorbent.
- the outer absorbent member 42 can be a contiguous piece of absorbent material
- central void 44 is defined by the space between the two strips.
- FIGS. 4A and 4B depict the transverse cross-section of an absorbent article 20 also comprising a central absorbent member 46 comprising an upper absorbent layer 32 and a pouch 36 comprising free-flowing particles 38 in a pouch 36 disposed beneath the
- upper absorbent layer 32 1470 upper absorbent layer 32; an outer absorbent member 42 having a central void 44 for receiving the central absorbent member 46; a wicking barrier 48 disposed between the central absorbent member 46 and the outer absorbent member 42.
- the pouch 36 is narrower than the upper absorbent layer 32.
- the upper absorbent layer 32 therefore assumes a convex upward shape predisposed to flex toward the body of the wearer
- the wicking barrier 48 extends below the pouch 36 of free-flowing particles 38 and has a vertical component 52 spanning a vertical distance along the inner walls of the central void 44 of the outer absorbent member 42, and further has a horizontal component 54 spanning a horizontal distance on the body-side surface of the outer absorbent
- the wicking barrier 48 can comprise multiple sections, such as two strips of polymeric film or two strips of a substantially liquid impervious nonwoven web extending along the longitudinal sides of the upper absorbent layer 32 to hinder wicking between the central absorbent member 46 and the outer absorbent member 42.
- the outer absorbent member 42 is divided along the transverse
- the outer absorbent member 42 is not divided but comprises a relatively thinner underlying portion 50 beneath the central absorbent member 46 and joining the two longitudinal sides of the outer absorbent member 42 along the transverse centeriine.
- the central void 44 is a depression and not a hole passing
- the pouch 36 can be disposed between two or more layers of absorbent material or particle restraining material (including the wicking barrier 48), in which case the free-flowing particles 38 can be restrained by the surrounding materials without the need for the pouch 36 depicted in the embodiment of FIG. 4B.
- FIG. 5 is a partial cutaway view of an absorbent article 20 according to the present invention.
- the article 20 comprises a topsheet 24, which is cut away to reveal several underlying components, particularly an upper absorbent member 32, which has a medial hump therein due to the presence of an underlying pouch 36 of free-flowing particles, depicted here in a truncated oval shape having a thickness substantially greater than the
- the upper absorbent member 32 further comprises a pair of optional, substantially longitudinal crease lines 56', 56" in the crotch region 60, the crease lines 56', 56" being spaced apart about the longitudinal centeriine of the article 20.
- the crease lines 56', 56" are transversely outside the longitudinal sides of the pouch 36 and within the longitudinal sides 58', 58" of the upper absorbent member 32.
- the crease lines 56', 56" also extend into the underlying lower absorbent member 34, which also has a thickness substantially lower than the pouch 36 of free-flowing particles in this embodiment.
- the crease lines 56', 56" in both the upper absorbent member 32 and the lower absorbent member 34 permit upward folding of the outer longitudinal sides of the lower absorbent member 34 and the upper absorbent member 32 to form a
- the upper absorbent member 32 and the pouch 36 can be any suitable absorbent member 32 and the pouch 36.
- FIG. 6 depicts cross-sectional views along transverse centerlines of absorbent articles showing several ways in which a pouch 36 of nits or other free-flowing particles 38 can serve as a conformable intake member disposed on an upper absorbent layer 32.
- the pouch 36 is disposed in a central void 44 within the upper absorbent layer 32.
- the pouch 36 is disposed in a central void 44 passing completely through the upper absorbent layer 32, with second layer, the lower absorbent layer 34 beneath the pouch 36.
- the lower absorbent layer 34 is preshaped to have a convex upward shape to predispose it to flex upward when inwardly laterally compressed, thus directing the pouch
- the upper absorbent layer 32 is preshaped for upward deflection when inwardly laterally compressed from the longitudinal sides.
- the upper absorbent layer 32 has a central shaping line 62 where the lower absorbent layer 34 has been scored, folded, stamped, embossed, or the like to promote upward flexure.
- a resilient deflection element 64 comprising a central hinge 66 is further disposed beneath
- the upper absorbent layer 32 to further control the deflection of the absorbent article toward the body of the wearer when the article is worn.
- FIG. 7 shows a partial cutaway view of an absorbent core 22 for use in an absorbent article (not shown) according to the present invention.
- the absorbent core 22 comprises an outer absorbent member 42 having a central elliptical hole therein for
- the outer absorbent member 42 can be an outer annular ring of absorbent material.
- the central absorbent member 46 comprises an inner annular ring 68 of absorbent material with an inner void therein, and a conformable intake member 30 comprising nits or free-flowing particles 38 in a liquid-pervious pouch 36 which prevents particles from escaping the conformable intake member 30.
- wicking barrier 48 Between the outer absorbent member 42 and the central absorbent member 46 is a wicking barrier 48, which comprises a vertical component 52 and a horizontal component 54 on or above the body-side surface of the outer absorbent member 42.
- FIG. 8 shows a "pillow pad” design based on the Raidel patent application (WO 98/01684), adapted according to the present invention to comprise nits.
- FIG. 7 shows a
- the pad 20 comprises a frontal region 70, a middle region 72 and a rear region 74.
- a liquid-pervious layer topsheet 24 and a liquid-impervious backsheet 26 are joined together at the periphery 28.
- the absorbent core 22 comprises a central absorbent member 46 and an outer absorbent member 42.
- the central absorbent member 46 comprises a pouch 36 containing cellulosic nits 38 therein.
- the pouch 36 may
- the pouch 36 is almost entirely filled with free- flowing particles 38 such as nits. Complete filling with nits does not pose any serious problem in use since the nits do not expand substantially upon wetting. If substantially swellable materials were also present, such as superabsorbent particles, the pouch 36
- the pouch 36 can comprise elastomeric material or pleats or folds that can allow the pouch 36 to expand when the free-flowing particles 38 and other absorbent materials inside the pouch 36 are wetted.
- Grooves 76 extend in the longitudinal direction of the article 20.
- the absorbent core comprises tied-in areas 78 which cause a degree of separation of the pouch 36 into a central chamber 80 and lateral chambers 82, 84.
- the delimitation walls of the individual chambers do not reach all the way to the base of the pouch 36, so that a limited degree of material exchange can occur between the individual chambers.
- the pouch 36 comprises two sections which are
- the pouch 36 depicted in FIG. 8 is substantially oval in shape and is backed by
- the lower absorbent layer 34 contributes to wearer comfort and to absorbency of the absorbent core 22.
- a wicking barrier (not shown) may also be present between the central absorbent member 46 and the outer absorbent member 42.
- absorbent layer 34 may comprise a polymeric film which desirably would extend past the peripheral margins 86 of the central absorbent member 46 such that some of the wicking barrier also extends on the body-side surface of the outer absorbent member 42 in the middle region 72 (crotch region) of the absorbent article 20 for improved leakage control. Without wishing to be bound by theory, it is believed that when the article 20
- the grooves 76 help distribute the fluid longitudinally, after which fluid can be taken up by the free-flowing particles 38 in the pouch 36.
- the grooves 76 are also believed to provide increased transverse flexibility of the absorbent article 20, providing for good body fit and comfort, while reducing the effective size of any one chamber 80, 82, 84, such that shifting of the particles 38 is not a
- FIGS. 9 and 10 were previously discussed in relation to the Angle of Repose test.
- FIGS. 11 and 12 were previously discussed in relation to the Gel Bed Permeability test.
- FIG. 13 depicts a flowchart for a process of making nits in which the stream of
- 1590 fibers is disperged more than once, allowing modifications in chemistry and process conditions to permit improved control over nit properties in the two or more separate steps. It has been discovered that a second step of disperging can help improve the flowability and absorbency properties of the nits.
- hardwood fibers or a slurry comprising hardwood fibers can be substantially curled or formed into nits in a first
- the mechanically treated fibers or nits can then be optionally dried, followed by adjustment of the moisture content to bring the consistency to about 18% or greater, or 20% or greater, such as from 20% to 30%. Thereafter the fibers are
- nits 1600 again subjected to disperging at a suitable energy level to create nits, which are then dried.
- a Maule shaft disperger can be used to create nits in a first step with an exit consistency of about 30% or higher, whereafter the consistency is reduced to from about 20% to about 30% for further mechanical processing in a Hobart mixer for high- consistency pulp.
- a second 1605 disperging step under different processing conditions can create new shear conditions that may help remove free fibers projecting from the surface of nits formed in the first step, fibers that may not have been sufficiently able to become entangled into the nit under the conditions of the first treatment.
- nit conditioners and disperger conditions in the first disperging step may be designed to control flock formation and the initial size of the nits to maximize yield in a desired size range.
- the second disperging step may further improved the size distribution and may use different chemistry aimed at modifying the surface of the first disperging step
- drying or partial drying after a first disperging step, followed by remoistening, a second disperging step, and final drying can promote hydrogen bonding of previously loose fibers with the
- 1620 parent nits such that the fibers are no longer projecting from the nits to the degree before.
- new hydrogen bonds can form between loose fibers and the other fibers in the nits from which the loose fibers project. If the nits are simply wetted and redried, new hydrogen bonds may form between projecting fibers and other nits, resulting in clumps. Disperging or mechanical shear is
- the use of two or more disperging steps offers additional combinations of temperature and chemistry to control the properties of the nits.
- the first disperging step may be done at an elevated pH (e.g., pH above 8, such as from 9 to 11 ), wherein the fibers are swollen and relatively flexible.
- the second disperging step may be performed under lower pH, such as a pH of from about 4 to 6, wherein the
- a first disperging step is conducted at low pH, followed by a second step at elevated pH, with the potential to produce nits that are relatively more round or that have other desired morphological properties.
- a first chemical can be added in a first disperging step, followed by addition of a second chemical in a second disperging step. This can be particularly helpful when the two chemicals would give undesired reactions when added simultaneously, such as an anionic compound and a cationic compound.
- 1645 debonder could be added in separate disperging steps. Or two charged compounds can be added that would normally interfere with each other or cause precipitation.
- FIG. 14 depicts a flowchart for preparing an absorbent article comprising two or more kinds of nits. Nits of a first fiber type and a second fiber type are prepared via disperging in the presence of nit conditioners and then dried, forming two material
- 1650 streams that can be independently exposed to post-treatments such as sorting by size by sieving, screening, or other classification methods, and such as chemical treatment, including deposition of hydrophobic matter on a portion of the outer surface of the nits.
- post-treatments such as sorting by size by sieving, screening, or other classification methods, and such as chemical treatment, including deposition of hydrophobic matter on a portion of the outer surface of the nits.
- the nits can then be combined and used to fill a pouch in an absorbent article. Alternatively, the nits may be combined prior to any of the post-treatments or even prior to
- FIGS. 15 to 17 show SEM micrographs of eucalyptus nits prepared according to conditions identified below in the Examples.
- FIG. 15 shows a rounded, ovoid nit substantially free of fibers ascending from the nit that could readily become entangled with other nits.
- the nit shown in FIG. 16 is still relatively free of fibers ascending from the surface, though it appears that two fibers do ascend.
- FIG. 17 is a cross-section of another
- 1665 eucalyptus nit produced with a Maule disperger, which was cut by a blade after being frozen in liquid nitrogen to reveal the interior structure.
- Example 1 Nit Preparation with a BIVIS Disperger
- the pulp was diluted to about 4.5% consistency and pumped over to the dump chest of a Bivis device while the agitator was running.
- the Bivis disperger (commonly termed an extruder by the manufacturer) was Model BC-45, manufactured by Clextral Inc., Firminy, France. Pumping was achieved using a pulper dump pump.
- the Bivis dump tank transfer pump was set to be in the recirculating mode.
- An Andritz belt press (Continuous Belt Press, Model CPF 0.5 meter, P3, Andritz-Ruthner, Inc., Arlington, TX) was used to dewater the pulp and discharge it into a screw conveyor system. Once activated, the feed valve off the Bivis Dump Tank Transfer Pump was opened and the recirculation valve was closed. The belt press was confuigured to give a discharge mat 2.5 cm thick. Discharge consistency was approximately 32 percent. This
- 1685 mat was broken up by the break-up screw at the end of the belt press and then was transferred by the screw conveying system to the feed hopper of the Bivis extruder.
- Pulp was further disintegrated by the double feed screw system in the bottom of the feed hopper.
- the disintegrated pulp was fed to the Bivis feed screw and directly into the Bivis extruder.
- the Bivis extruder is a double screw, co-rotating extruder with the
- the debonder was a quanternary ammonium compound, MacKerniumTM 516Q-60 1705 (Mclntyre Group, Ltd., Chicago, Illinois) added at a dose of 2.78 kg (6.15 pounds) per metric ton.
- Pulp was discharged from the Belt Press at approximately 35% consistency to a break-up screw and thence to the Maule kneader/disperger by a heating screw, to raise 1720 the kneader inlet temperature to 80°C. Kneader outlet temperature was approximately 100°C. Target specific energy for the kneader was 98 kW-hr/ton (5.5 horsepower-days per ton).
- One run was performed using the preceding procedure with the following exception: The outlet door to the kneader was closed and the kneader was operated with 1725 a rotor speed of 48 rpm for 10 minutes. This resulted in a higher energy input to pulp, causing the nits to be smaller with fewer fibers projecting from the surface of the nits, resulting in an improvement in the flowability of the nits.
- Bleached kraft eucalyptus pulp from Cenibra, Inc. was disperged in a Maule 1730 disperger at an entry temperature of about 25°C (room temperature) and an inlet consistency of 20% to form nits.
- Berocell 584 debonder was added a level of 3 kg/ton prior to disperging.
- Nits were spread onto flat surfaces to a depth of about 2 cm and air dried overnight. The nits proved to be free flowing and were substantially free of free fibers rising from the surfaces of the nits that could cause entanglement between nits.
- the 1735 nits were screened to a size range between about 300 and 850 microns and then encased in spunbond nonwoven webs and sealed with heat sealing to produce particulate pouches suitable for incorporation into absorbent articles.
- a useful range can be from 300 microns to 600 microns for good containment of the nits and product comfort. Larger nits, in some cases, can more likely be perceived as grainy or uncomfortable.
- the percent yield for the particle size range 300 microns to 600 microns was much higher when debonder had been added to the pulp than without
- the addition of debonder improves the Centrifuge Retention Capacity value - a surprising result given that
- the debonder has a hydrophobic nature.
- the debonder was MacKernium 516Q-60 at 2.78 kg (6.15 pounds) per metric ton of pulp.
- the eucalyptus nits were made on the Maule machine and oven dried over night at 43°C.
- the control codes were non-debonded Weyerhaeuser NB416 pulp and debonded Weyerhaeuser NF405 pulp. Pulp-based materials with debonder normally reduce the centrifuge retention capacity value as shown.
- the fluid intake and flow back values of eucalyptus nits is another property which 1775 can be considered.
- a fast intake and low flow back value can be useful in some embodiments.
- Table 5 shows the fluid intake and flow-back on the raw material (the Maule-produced eucalyptus nits), performed according to the Raw Material Absorbency Rate and Rewet Test Method given above.
- the third insult is 1 ml, while the first two use 2 ml of fluid.
- the time required for taking in the second insult is 1780 generally roughly the same as the time required for the first insult, and the time required for the third insult when doubled to normalize it to 2 ml is still only slightly greater than required for the first or second insults.
- the nits of the present example show an ability to take fluid in at a high rate even after multiple insults.
- Table 6 shows the fluid intake and flow-back for eucalyptus nits enclosed in a pouch or "pillow case,” prepared and measured according to the Intake and Rewet Test given above.
- the non-debonded nits also had higher flow-back values than those with the
- Permeability testing was performed to determine the acceptable range of permeability for debonded Eucalyptus nits compared to three control materials.
- the control materials were non-debonded eucalyptus nits, CF-405 pulp from Weyerhaeuser 1805 Corporation (a debonded pulp), and NB416 pulp from Weyerhaeuser Corporation.
- the test method used to determine permeability was the Gel Bed Permeability test given above and the flow back test method was Intake and Rewet Test Method given above (for nits encased in a pouch). The data are summarized in Table 7 below.
- a high permeability permits rapid fluid intake.
- a high permeability value for eucalyptus nits correlates to a high rewet value which creates a wet surface against the body.
- Lower permeability allows for fast fluid intake but less available void volume, which
- a used permeability range is believed to exist below about 7 x 10 "7 cm 2 , such as a range between about 3 x 10 "7 cm 2 and about 7 "7 x 10,
- FFC 1825 Coefficient
- Coefficient values greater than 2 and also greater than 3 are indicative of a material with a degree of free flowing behavior.
- Nits with substantially higher flowability have been prepared, such as those of Example 8 below, and are expected to have even higher Flowability Coefficients.
- highly flowable particles for use in the present invention can also have a Flowability Coefficient of 3.5 or greater or of about 4 or greater.
- the effective angle of internal friction can also be related to flowability or tendency to bridge in hopper flow.
- the effective angle of internal friction can be from about 40° to about 67°, or from about 40° to about 60°. The testing in this case did not show strong differences in the measured parameters for the nits with and without debonder. 1845 Table 8. Jenike Shear Cell Data for Sieved Maule-produced Nits.
- Compressibility testing also performed by Jenike & Johanson yielded density values of up to 232 kg/cubic meter (14.5 pounds per cubic foot) for both sets of nits 1850 tested, with a range of from 104 kg/cubic meter 6.5 to 232 kg/cubic meter, with the variation due to possible voids inside the bed of nits when the nits were poured into a contained.
- Eucalyptus nits were also produced on the BIVIS equipment described above. 1855 Table 9 lists the centrifuge retention capacity values for eucalyptus nits with MacKernium 516Q-60 debonder at three different levels. The eucalyptus nits were oven dried over night at 43°C. An increase in debonder did not appear to reduce the absorbent capacity of the nits.
- control codes were non-debonded Weyerhaeuser NB416 pulp and debonded 1860 Weyerhaeuser NF405 pulp. Pulp-based materials with debonder normally reduce the centrifuge retention capacity value as shown.
- the oval pouch was placed on top of and in the center of a pre-cut, pre-adhesive sprayed hour glass shaped 90-gsm coform layer.
- the coform layer was 210 mm long and 65 m wide and constructed of 60 percent polypropylene and 40 percent pulp. The coform was adhesively attached to
- Astroglide® injected into the middle of the pouch. Astroglide® was injected into the center of the pouch using a syringe and needle and uniformly distributed in the pouch. Astroglide® is a personal lubricant manufactured by BioFilm, lnc.(Vista, CA). The subjects completed a questionnaire to rate the following attributes: pad comfort, pad softness, and
- One useful eucalyptus nits particle size range is from 20 to 50 mesh and more specifically greater than 30 mesh but less than 50 mesh.
- a 175-gsm airlaid densified web with a density of about 0.1 g/cc was cut to a dumbbell shape with a length of about 21.5 cm and a width at the transverse centeriine of about 6 cm.
- a central region of the outer absorbent member was removed by a die cutting operation to provide a central void in the outer absorbent member 42.7 cm long and 3.7
- the dumbbell-shaped outer absorbent member was placed on a 20-gsm polyethylene backsheet provided with contact adhesive.
- the backsheet was substantially larger than the dumbbell-shaped absorbent web.
- a rose-colored 20-gsm polyethylene film was die cut to be a rounded rectangle 20.3 cm long by 4.7 cm in width and was centrally placed over the central void to serve as a wicking barrier. 3.3 grams of loose nits were
- the nits were made of bleached kraft eucalyptus fibers which had been mechanically curled and disperged to form small dense floes about 1 mm in diameter.
- the nits were prepared by taking 20 grams of dry eucalyptus pulp that had been previously disperged in the moist state (about 30% consistency) in a Maule disperger, then further
- FIG. 15 is a micrograph from a scanning electron microscope (SEM) showing a characteristic nit from this batch.
- the nit is substantially ovoid in shape and is substantially free of loose fibers projecting from the surface of the
- FIG. 16 shows a form of a nit having projecting fibers rising from the surface of the nit.
- the dry, loose nits were placed over the wicking barrier film inside the void of the outer absorbent member and covered with the a 20-gsm spunbond polypropylene topsheet, which served to hold the nits in place and function as the upper half of an
- the topsheet was provided with contact adhesive on the side toward the absorbent core, permitting it to join to the horizontal component of the wicking barrier and form a seal to hold the nits in place.
- the topsheet had also been treated with 0.3% by weight of a surfactant comprising 45 wt. % polyethoxlated hydrogenated ethoxylated castor oil and 55
- the entire article was die cut with a dumbbell- shaped die having dimensions greater than the outer absorbent member (24.4 cm long, 8 cm wide at the transverse centeriine) to provide a rim of backsheet material and cover material around the outer absorbent member in an absorbent article having good integrity
- a loop of the colored barrier material was visible through the translucent topsheet (the horizontal component of the pink wicking barrier).
- the central absorbent member comprising nits was conformable, flexible, and had a comfortable, soft feel.
- Sanitary napkins were assembled generally according to Example 7, except that the nits were first encased in an encasement comprising a 20-gsm spunbond polypropylene web. Experimental use tests with menstruating subjects were conducted using nits that were treated with debonder as well as nits not treated with debonder. 1950 Based on visual appearance and leakage of the used products, the absorbent articles comprising nits treated with debonder provided better intake and fluid handling performance.
- the second disperging step improved flowability by adding more energy to the nits to create dense, compacted structure, by providing new shear conditions that could bring loose fibers into back into contact with the 1990 nits, and by allowing hydrogen bonds to form between loose fibers and their parent nits.
- the addition of silicone helped prevent clumping and may have allowed for better break-up of nits during disperging to yield smaller particle sizes, while also enhancing lubricity between dry nits.
- Other lubricants and debonders are expected to have a similar effect in promoting good 1995 particle size distribution during disperging, whether in a first or second disperging step.
- Example 10 a variety of feminine care products can be prepared from the nits produced in any of the above Examples.
- Example 10 a pre-cut oval pouch made from polyolefin spunbond webs can be filled with nits and optionally with odor-control
- 2000 compounds such as zeolites and sealed around the edges ultrasonically or thermally.
- the pouch can be attached to an underlying absorbent layer such as coform, airlaid or a fluff batt.
- a spunbond cover is placed over the pouch and attached with adhesive to form a sanitary napkin.
- Example 11 a pre-cut oval pouch can be filled with a layer of superabsorbent
- the pouch is attached to an absorbent layer such as coform, airlaid or a fluff batt.
- a spunbond cover is placed over the pouch and attached with adhesive.
- a section of an activated carbon fabric may also be attached to the coform for odor control.
- Example 12 a liquid-pervious pouch is filled with superabsorbent and nits which are mixed together and the pouch is sealed around all edges.
- the pouch is attached to an absorbent layer such as coform, airlaid or a fluff batt.
- a spunbond cover is placed over the pouch and attached with adhesive.
- Example 13 a layer of nits is sandwiched between a layer of low basis weight
- Example 14 a pantiliner is formed from a layer of nits comprising eucalyptus fibers that is sandwiched between a layer of low basis weight coform or airlaid (less than 120 gsm) and a backsheet. A spunbond cover is placed over the absorbent and the 2020 pantiliner is sealed with heat around the edges.
- Example 15 a tampon is filled with nits with or without superabsorbent and a nonwoven cover stock is wrapped around the nits for containment.
- Example 16 a tampon is filled in the center with nits with or without superabsorbent and a layer of airlaid or fluff batt is wrapped around the nits and a cover 2025 stock material is attached to the airlaid or fluff batt.
Abstract
Description
Claims
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
BR0009807-8A BR0009807A (en) | 1999-04-16 | 2000-04-17 | Absorbent fibrous nits and processes for preparing fibrous nits that are useful in an absorbent article |
AU43567/00A AU4356700A (en) | 1999-04-16 | 2000-04-17 | Absorbent articles and methods for producing the same |
PL00366308A PL366308A1 (en) | 1999-04-16 | 2000-04-17 | Absorbent articles and methods for producing the same |
JP2000612560A JP2003529681A (en) | 1999-04-16 | 2000-04-17 | Absorbent article and manufacturing method thereof |
KR1020017013126A KR20020003562A (en) | 1999-04-16 | 2000-04-17 | Absorbent Articles and Methods for Producing the Same |
EP00923445A EP1175528A1 (en) | 1999-04-16 | 2000-04-17 | Absorbent articles and method for producing the same |
MXPA01010451A MXPA01010451A (en) | 1999-04-16 | 2000-04-17 | Absorbent articles and methods for producing the same. |
Applications Claiming Priority (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12975299P | 1999-04-16 | 1999-04-16 | |
US12974699P | 1999-04-16 | 1999-04-16 | |
US60/129,752 | 1999-04-16 | ||
US60/129,746 | 1999-04-16 | ||
US54775400A | 2000-04-12 | 2000-04-12 | |
US09/547,202 US6562192B1 (en) | 1998-10-02 | 2000-04-12 | Absorbent articles with absorbent free-flowing particles and methods for producing the same |
US09/547,754 | 2000-04-12 | ||
US09/547,202 | 2000-04-12 |
Publications (1)
Publication Number | Publication Date |
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WO2000063487A1 true WO2000063487A1 (en) | 2000-10-26 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2000/010326 WO2000063487A1 (en) | 1999-04-16 | 2000-04-17 | Absorbent articles and methods for producing the same |
Country Status (11)
Country | Link |
---|---|
EP (1) | EP1175528A1 (en) |
JP (1) | JP2003529681A (en) |
KR (1) | KR20020003562A (en) |
CN (1) | CN1354810A (en) |
AU (1) | AU4356700A (en) |
BR (1) | BR0009807A (en) |
MX (1) | MXPA01010451A (en) |
PE (1) | PE20001412A1 (en) |
PL (1) | PL366308A1 (en) |
TR (1) | TR200102990T2 (en) |
WO (1) | WO2000063487A1 (en) |
Cited By (16)
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WO2001060297A1 (en) * | 2000-02-18 | 2001-08-23 | Hakle-Kimberly Deutschland Gmbh | Absorbent articles |
FR2831564A1 (en) * | 2001-10-30 | 2003-05-02 | Weyerhaeuser Compagny | Production of dry cellulose fibres from pulp uses jet drier with pulp and air feeds with pre-drying additive to prevent knots |
FR2834727A1 (en) * | 2002-01-16 | 2003-07-18 | Weyerhaeuser Compagny | PRODUCT CONSISTING OF DISSSOCIATED, RETICULATED AND DRY FIBER PULP |
FR2834728A1 (en) * | 2002-01-16 | 2003-07-18 | Weyerhaeuser Compagny | PROCESS FOR THE PRODUCTION OF DISSOCIATED AND RETICULATED PULP FIBERS AND THESE FIBERS |
FR2834729A1 (en) * | 2002-01-16 | 2003-07-18 | Weyerhaeuser Compagny | SYSTEM FOR DRYING A RETICULATED AND DISSOCIATED FIBER PULP |
WO2004061201A1 (en) * | 2002-12-26 | 2004-07-22 | Kimberly-Clark Worldwide, Inc. | Method of producing twisted, curly fibers |
WO2006065110A1 (en) * | 2004-12-15 | 2006-06-22 | Flores Gonzalez Estela Concepc | Improvements to ecological and biodegradable absorbent articles |
US7122174B2 (en) | 2002-09-30 | 2006-10-17 | L'oreal S.A. | Compositions comprising at least one silicone compound and at least one amine compound, and methods for using the same |
US7196022B2 (en) | 2001-12-20 | 2007-03-27 | Kimberly-Clark Worldwide, Inc. | Products for controlling microbial generated odors |
US7795345B2 (en) | 2003-04-25 | 2010-09-14 | Evonik Stockhausen, Llc | Superabsorbent polymer with high permeability |
US7858841B2 (en) | 2002-12-11 | 2010-12-28 | Kimberly-Clark Worldwide, Inc. | Enhanced body conformance with the use of free flowing particles |
WO2011028823A1 (en) * | 2009-09-01 | 2011-03-10 | Armstrong World Industries, Inc. | Cellulosic product forming process and wet formed cellulosic product |
US8021998B2 (en) | 2003-04-25 | 2011-09-20 | Kimberly-Clark Worldwide, Inc. | Absorbent structure with superabsorbent material |
EP2832326A4 (en) * | 2012-03-30 | 2015-07-29 | Unicharm Corp | Absorbent article |
WO2015175328A1 (en) * | 2014-05-13 | 2015-11-19 | The Procter & Gamble Company | Absorbent article with dual core |
US9248213B2 (en) | 2005-12-22 | 2016-02-02 | Sca Hygiene Products Ab | Absorbent article |
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TWI355261B (en) * | 2003-12-11 | 2012-01-01 | Kao Corp | Topsheet for absorbent article and absorbent arti |
US8653322B2 (en) * | 2004-05-14 | 2014-02-18 | Mcneil-Ppc, Inc. | Intravaginal device with fluid transport plates |
JP4314292B2 (en) * | 2007-09-25 | 2009-08-12 | 憲司 中村 | Makeup tissue paper |
JP5132264B2 (en) * | 2007-11-07 | 2013-01-30 | 花王株式会社 | Absorbent articles |
CN102579198B (en) * | 2012-02-20 | 2014-06-18 | 福建益川自动化设备股份公司 | Method for producing simple training pant and device for processing the same |
US9617686B2 (en) * | 2012-04-18 | 2017-04-11 | Gp Cellulose Gmbh | Use of surfactant to treat pulp and improve the incorporation of kraft pulp into fiber for the production of viscose and other secondary fiber products |
JP6199243B2 (en) * | 2014-06-12 | 2017-09-20 | ユニ・チャーム株式会社 | Method for producing recycled pulp from used sanitary products |
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WO1996017573A2 (en) * | 1994-12-09 | 1996-06-13 | The Procter & Gamble Company | Absorbent composites and absorbent articles containing the same |
US5800417A (en) * | 1995-12-12 | 1998-09-01 | Goerg-Wood; Kristin Ann | Absorbent composition comprising hydrogel-forming polymeric material and fiber bundles |
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2000
- 2000-04-17 TR TR2001/02990T patent/TR200102990T2/en unknown
- 2000-04-17 CN CN00806256A patent/CN1354810A/en active Pending
- 2000-04-17 AU AU43567/00A patent/AU4356700A/en not_active Abandoned
- 2000-04-17 MX MXPA01010451A patent/MXPA01010451A/en active IP Right Grant
- 2000-04-17 EP EP00923445A patent/EP1175528A1/en not_active Withdrawn
- 2000-04-17 PE PE2000000356A patent/PE20001412A1/en not_active Application Discontinuation
- 2000-04-17 WO PCT/US2000/010326 patent/WO2000063487A1/en not_active Application Discontinuation
- 2000-04-17 KR KR1020017013126A patent/KR20020003562A/en not_active Application Discontinuation
- 2000-04-17 PL PL00366308A patent/PL366308A1/en not_active Application Discontinuation
- 2000-04-17 JP JP2000612560A patent/JP2003529681A/en active Pending
- 2000-04-17 BR BR0009807-8A patent/BR0009807A/en not_active Application Discontinuation
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FR1554951A (en) * | 1967-02-01 | 1969-01-24 | ||
EP0225940A1 (en) * | 1985-12-20 | 1987-06-24 | Maria Scamvougeras | Process for the production of disposable hygienic goods and fluff pulp for using in this process |
WO1996017573A2 (en) * | 1994-12-09 | 1996-06-13 | The Procter & Gamble Company | Absorbent composites and absorbent articles containing the same |
US5800417A (en) * | 1995-12-12 | 1998-09-01 | Goerg-Wood; Kristin Ann | Absorbent composition comprising hydrogel-forming polymeric material and fiber bundles |
Cited By (28)
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GB2379674A (en) * | 2000-02-18 | 2003-03-19 | Hakle Kimberly De Gmbh | Absorbent articles |
GB2379674B (en) * | 2000-02-18 | 2004-02-18 | Hakle Kimberly De Gmbh | Absorbent articles with cellulose fibres in the form of granules |
WO2001060297A1 (en) * | 2000-02-18 | 2001-08-23 | Hakle-Kimberly Deutschland Gmbh | Absorbent articles |
FR2831564A1 (en) * | 2001-10-30 | 2003-05-02 | Weyerhaeuser Compagny | Production of dry cellulose fibres from pulp uses jet drier with pulp and air feeds with pre-drying additive to prevent knots |
US6910285B2 (en) | 2001-10-30 | 2005-06-28 | Weyerhaeuser Company | Process to produce dried singulated cellulose pulp fibers |
US7290353B2 (en) | 2001-10-30 | 2007-11-06 | Weyerhaeuser Company | System for making dried singulated crosslinked cellulose pulp fibers |
US7196022B2 (en) | 2001-12-20 | 2007-03-27 | Kimberly-Clark Worldwide, Inc. | Products for controlling microbial generated odors |
FR2834727A1 (en) * | 2002-01-16 | 2003-07-18 | Weyerhaeuser Compagny | PRODUCT CONSISTING OF DISSSOCIATED, RETICULATED AND DRY FIBER PULP |
FR2834728A1 (en) * | 2002-01-16 | 2003-07-18 | Weyerhaeuser Compagny | PROCESS FOR THE PRODUCTION OF DISSOCIATED AND RETICULATED PULP FIBERS AND THESE FIBERS |
FR2834729A1 (en) * | 2002-01-16 | 2003-07-18 | Weyerhaeuser Compagny | SYSTEM FOR DRYING A RETICULATED AND DISSOCIATED FIBER PULP |
US7122174B2 (en) | 2002-09-30 | 2006-10-17 | L'oreal S.A. | Compositions comprising at least one silicone compound and at least one amine compound, and methods for using the same |
US7858841B2 (en) | 2002-12-11 | 2010-12-28 | Kimberly-Clark Worldwide, Inc. | Enhanced body conformance with the use of free flowing particles |
US7364639B2 (en) | 2002-12-26 | 2008-04-29 | Kimberly-Clark Worldwide, Inc. | Method of producing twisted, curly fibers |
US6984447B2 (en) | 2002-12-26 | 2006-01-10 | Kimberly-Clark Worldwide, Inc. | Method of producing twisted, curly fibers |
WO2004061201A1 (en) * | 2002-12-26 | 2004-07-22 | Kimberly-Clark Worldwide, Inc. | Method of producing twisted, curly fibers |
US7795345B2 (en) | 2003-04-25 | 2010-09-14 | Evonik Stockhausen, Llc | Superabsorbent polymer with high permeability |
US8021998B2 (en) | 2003-04-25 | 2011-09-20 | Kimberly-Clark Worldwide, Inc. | Absorbent structure with superabsorbent material |
WO2006065110A1 (en) * | 2004-12-15 | 2006-06-22 | Flores Gonzalez Estela Concepc | Improvements to ecological and biodegradable absorbent articles |
US9248213B2 (en) | 2005-12-22 | 2016-02-02 | Sca Hygiene Products Ab | Absorbent article |
US8328987B2 (en) | 2009-09-01 | 2012-12-11 | Armstrong World Industries, Inc. | Process of making a wet formed cellulosic product and a wet formed cellulosic product |
US8741105B2 (en) | 2009-09-01 | 2014-06-03 | Awi Licensing Company | Cellulosic product forming process and wet formed cellulosic product |
WO2011028823A1 (en) * | 2009-09-01 | 2011-03-10 | Armstrong World Industries, Inc. | Cellulosic product forming process and wet formed cellulosic product |
US9365977B2 (en) | 2009-09-01 | 2016-06-14 | Awi Licensing Llc | Cellulosic product forming process and wet formed cellulosic product |
EP2832326A4 (en) * | 2012-03-30 | 2015-07-29 | Unicharm Corp | Absorbent article |
US9233185B2 (en) | 2012-03-30 | 2016-01-12 | Unicharm Corporation | Absorbent article |
WO2015175328A1 (en) * | 2014-05-13 | 2015-11-19 | The Procter & Gamble Company | Absorbent article with dual core |
US10398610B2 (en) | 2014-05-13 | 2019-09-03 | The Procter & Gamble Company | Absorbent article with dual core |
US11752046B2 (en) | 2014-05-13 | 2023-09-12 | The Procter And Gamble Company | Absorbent article with dual core |
Also Published As
Publication number | Publication date |
---|---|
BR0009807A (en) | 2002-11-26 |
AU4356700A (en) | 2000-11-02 |
PL366308A1 (en) | 2005-01-24 |
KR20020003562A (en) | 2002-01-12 |
TR200102990T2 (en) | 2002-10-21 |
MXPA01010451A (en) | 2002-09-18 |
PE20001412A1 (en) | 2000-12-13 |
JP2003529681A (en) | 2003-10-07 |
CN1354810A (en) | 2002-06-19 |
EP1175528A1 (en) | 2002-01-30 |
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