US3559649A

US3559649A - Sanitary napkin

Info

Publication number: US3559649A
Application number: US692003A
Authority: US
Inventors: Martin Grad; Darrel D Kokx
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1967-12-20
Filing date: 1967-12-20
Publication date: 1971-02-02
Anticipated expiration: 1988-02-02

Abstract

A sanitary napkin comprising an absorbent pad enwrapped by a fluid pervious outer cover treated with a fluid-repellent material along areas overlying the side edges and side marginal portions of the top face of the pad, the treated areas being permeable to air. The fluid-repellent treatment material contains a fluorescent indicator substance and imparts an AATCC spray rating of about 100 to the treated areas.

Description

United States Patent 2,067,961 1 1937' Williams CONTAINING A FLUORES INDICATOR SUBSTANCE AND IMPARTING AN AATCC SPRAY RATING 0F ABOUT IOO Martin Grad Cincinnati;

Darrel D. Kokx, Greenhills. Ohio 692,003

Dec. 20, 1967 Feb. 2, 1971 The Procter & Gamble Co. Cincinnati, Ohio a corporation of Ohio Inventors Appl. No. Filed Patented Assignee SANITARY NAPKIN 1 Claim, 3 Drawing Figs.

US. Cl 128/290 Int. Cl t A6lf 13/16 Field of Search l28/290W,

290(1nquired) References Cited UNITED STATES PATENTS AREAS TREATED WlTH FLUlD-REPELLENT MATERIAL/ cam I Hermanson 128/290 2,536,631 l/l95l 128/290 3,056,406 10/ l 962 128/290 3,308,826 3/1967 128/290 Primary Examiner-Richard C. Pinkham Assistant Examiner-Theatrice Brown Att0rneys.l0hn V. Gorman and Richard C. Witte ABSTRACT: A sanitary napkin comprising an absorbent pad end/rapped by a fluid pervious outer cover treated with a fluid-repellent material along areas overlying the side edges and side marginal portions of the top face of the pad, the treated areas being permeable to air. The fluid-repellent treatment material contains a fluorescent indicator substance and imparts an AATCC spray rating of about 100 to the treated areas.

FLU l D- PERVIOUS FABRIC OUTER COVER MOISTURE-l MPERMEABLE FILM PATENIEI] FEB 2 MI 3; 559,649

FLUID-PERVIOUS FABRIC OUTER COVER ABSORBENT PAD AREAS TREATED WITH 2 FLUID-REPELLENT MATERLAL/ CONTAINING A FLUORESCENT INDICATOR SUBSTANCE AND IMPARTING AN AATCC SPRAY RATING OF ABOUT I00 I N VliNl ()RS Martin Grad HY Darrel D. Kokx SANITARY NAPKIN FiELD OF THE INVENTION This invention relates to a sanitary napkin and more particularly to an enwrapped sanitary napkin in which the lateral spread of fluids deposited on the surface of the product is impeded.

BACKGROUND OF THE INVENTION One of the principal problems which has been faced in the sanitary napkin field is the poor performance of such products with respect to utilization of potential absorbent capacity. For example, it is common for sanitary napkins to absorb between 7 to 12 grams of 'rnenses before failure in use when the theoretical capacity of the system is several times that amount, perhaps in the range of 60 to 80 grams.

Lateral spreading of fluids deposited on the surface of the product is frequently the cause of premature in-use failure. This type of failure can occur after only a small portion of the material in the napkin absorbs fluid and is manifested by soiling of undergarments and the thighs of the user. Such failure is particularly troublesome when line bonded nonwoven fabrics are used as an outercover for napkins having a curved shape. In such products the use of line bonded nonwovens is advantageous from an appearance and comfort standpoint but, as indicated, compounds the lateral spread failure problem because of the large number of wrinkles formed transversely on the upper napkin surface.

In order to combat this type of failure (i.e., soiling over the sides of the sanitary napkin) many solutions have been proposed, including polyethylene film wraps and water-repellent side strips between the outer cover and the absorbent pad. These have been found to be helpful in some respects but do not prevent soiling of fluids moving over or wicking along the outercover. In this connection, such structures are still prone to prematurely fail by soiling of undergarments and the thighs of the user because of such movement or wicking on the outercover. Moreover, most of these solutions involve structures which when placed adjacent the skin of the user, feel hot and uncomfortable due to blocking of air circulation.

OBJECTS OF THE INVENTION It is an object of the present invention to improve the in-use absorbent capacity utilization of sanitary napkins.

It is a further object of the present invention to provide a sanitary napkin which failure because of lateral spreading of fluids deposited on the surface of the product is substantially reduced.

It is also an object of the present invention to provide a line bonded nonwoven fabric outercover for a sanitary napkin which resists the lateral spreading of fluids on the surface thereof.

It is another object of the present invention to provide a sanitary napkin which prevents premature failure by lateral spreading of menses, is economical to manufacture and comfortable in use.

It is a still further object of the present invention to provide, in an outercover for a sanitary napkin, resistance to side failure due to menses being squeezed outwardly during use.

SUMMARY OF Tl-IE INVENTION Briefly stated, in accordance with one aspect of the invention, there is provided a sanitary napkin comprising an absorbent pad enwrapped within a porous, fluid-pervious outercover which is treated with a fluid-repellent material along areas overlying the side edges and the side marginal portions of the top face of the pad.

BRIEF DESCRIPTION OF THE DRAWINGS i While the specification concludes with claims particularly is regarded as the present invention, it is believed that the invention will be better understood from the following description taken in connection with the accompanying drawing, in which:

FIG. I is a perspective view. partly broken away to show internal construction, of one embodiment of the present invention;

FIG. 2 is an enlarged fragmentary sectional view taken along line 2-2 of FIG. 1; and

FIG. 3 is a fragmentary plan view of the outercover of the napkin of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG, 1, there is shown a sanitary napkin 10 comprising an absorbent pad 12, the lower face and portions of the sides of which are protected by a moisture-impermeable film 14. The absorbent pad-film l4 assembly is overwrapped with an outercover 16 having

end extensions

18, 20 by means of which the napkin can be affixed to a sanitary belt.

The absorbent pad 12 can comprise any suitable absorbent material such as comminuted wood pulp fibers, creped cellulose wadding or the like. The size and shape of the pad can be varied without effect on the present invention. The pad 12 can, for example, be substantially rectangular in horizontal and vertical section, have a width of 2% inches, a length of 8 inches, a thickness of 1 inch and weigh approximately ll grams. In the illustrated embodiment (see FIG. 2) the side edges of the pad 12 are rounded so that a pad of the foregoing dimensions has a vertical cross-sectional periphery of about 6 /4 inches.

The film 14, if used, can comprise any suitable and compliant moisture impermeable membrane. It has bee found that one-half mil polyethylene film having a length approximating or somewhat greater than that of the pad 12 and a width slightly greater than the width of the pad 12, for example about 3% inch wide can be used with a pad 12 sized as described above. The purpose of the film 14 is to prevent strike-through menses which has penetrated the full thickness of the pad 12. While the film 14 can ordinarily be made to cover all of the pad 12 with the exception of the portion to be placed adjacent the vulva of the consumer in use, when used with napkins 10 of the present invention it should preferably cover as little as possible of the body-contacting areas because such materials when so-positioned reduce air circulation and make the napkin 10 feel hot and uncomfortable.

The outercover 16 can be about l9 inches long and has a width sufficient to encircle the transverse section of the napkin with slight overlap permitting the longitudinal edges of the fabric (which extend lengthwise of the napkin) to be united by adhesives, mechanical l or /4 means well known in the art. In the illustrated embodiment using the size of the is pad 12 described above, the cover width can be about 6% inches whereby an overlap of about 1% inch results. The fabric can be selected from many satisfactory materials such as gauze, knitted scrims or bonded nonwoven materials, apertured or non-apertured. Preferably, the fabric is white, porous, fluidpervious, absorptive, soft, smooth surfaced, strong in at least one direction and resistant to pilling. Such a fabric will look and feel good to a consumer as well as perform satisfactorily as an outercover 16 when practicing the present invention. One fabric which has been found to perform particularly well in connection with sanitary napkins and to which the present invention is especially well adapted for use is a line bonded rayon nonwoven material. Such a material can have a caliper or thickness of about 0.004 inch and a weight of approximately .53 ounce per square yard, for example. The rayon fibers can be selected from a wide range of suitable sizes and can, for example, be of from about lk to about 3 denier and have a length of about lb inch. A very satisfactory such line-bonded rayon nonwoven material is presently being marketed by Chicopee Mills, Inc. being designated as Viskon" nonwoven,

pointing out and distinctly claiming the subject matter which Code A-230 3552.

As shown most clearly in FIG. I. the outercover 16 is treated with a fluid-repellent material along

areas

22 and 24 which overlie the side edges and the side marginal portions of the top face of pad 12. The fluid-repellent material can be any of the well known hydrophobic substances which imparts an AATCC (American Association of Textile Chemists and Colorists) spray rating of at least about 70. and preferably I00. to the treated

areas

22 and 24 of the outercover. If it results in a spray rating of less the 70, the

areas

22 and 24 will not be sufficiently fluid-repellent. As indicated. such a spray rating should preferably be about I since this will assure stable, long-lasting resistance to wicking and flow over the treated

areas

22 and 24 and thus prevent the same from causing premature failure. With respect to quantity, the upper limit thereof is usually regulated by its effect on the drape and hand of the treated areas (desirably these should not be changed from that of the balance of the outercover) or, possibly, on the basis of cost or discoloration considerations, while the lower limit is set on the basis of minimum satisfactory performance. The procedure for determination of AATCC spray rating of fluid-repellent materials is set forth in AATCC Standard Test Method 22: I964. An outercover 16 the treated

areas

22 and 24 of which has a rating of less than about 70 will not achieve the principal object of the present invention, i.e., preventing premature in-use failure because of lateral spreading of fluids.

The fluid repellent material desirably has other properties to enhance its value in connection with the present invention and/or the ease with which sanitary napkins incorporating the treating material can be manufactured. For example, the substance preferably does not require a cure at elevated temperatures, is rub resistant (i.e., will not transfer to the skin of the user or smear or migrate from the treated to the untreated areas of the outercover 16), is colorless, nonyellowing, insoluble in body fluids and does not prevent

tab

18 and 20 formation and gluing, if this is done. In addition, it is preferred that the fluid-repellent material be capable of application with a nonflammable solvent base. preferably water, and, as before stated, that the hand and feel of the outercover 16 remain substantially unchanged after treatment so that, for example, the

areas

22 and 24 do not have a slippery or rubbery feel.

The material comprising outercover 16, the type of fluidrepellent material and, to some extend, the quantities thereof used should be such that the treated

areas

22 and 24 are porous, i.e., breathable. Breathability of the treated

ares areas

22 and 24 can be checked by placing the same against a moist area of a human body. If it feels hot,'breathability is lacking; if comfortable, breathability is adequate. If the treated

areas

22 and 24 are not porous (for example, if a thick continuous coating of wax has been applied), circulation of air therethrough will be restricted and the sanitary napkin will feel hot and uncomfortable in use.

A number of very satisfactory fluid-repellent materials well adapted for use in the present invention are available commercially. These fluid-repellent materials can be any of the wellknown hydrophobic substances such as wax, paraffin, metallic salt-wax emulsions, silicones, fluorochemicals and the like. One preferred such fluid-repellent material is an air drying silicone manufactured and sold be Dow Corning Corporation, Midland, Michigan as C-2-05 l0 water-repellent. This Product is a liquid containing 50 percent solids and cures at room temperature. The solvent employed is lsopar G (product of Humble Oil & Refining Company, Baltimore, Maryland), a narrow-, cut isoparafi'mic hydrocarbon fraction. Another preferred fluid-repellent material is a synthetic sizing agent sold by the American Cyanamid Company, Wayne, New Jersey, under the trademark Cyanasize 400" in the form of a 6 percent aqueous emulsion.

Other satisfactory fluid-repellent materials can, for example, comprise metallic (e.g., zirconium and aluminum) saltwax emulsions. From the standpoint of final appearance and performance such emulsions containing aluminum salts are more satisfactory than those incorporating zirconium. Illustrative of such products are Aridex L concentrated renewable water repellent (product of E. l. duPont DeNemours & Co.. Wilmington, Delaware). an acidic complex of waxes and aluminum salts, and Hypel water repellent finish (product of Burkart-Schier Chemical Company, Chattanooga Tenn.). a 25 percent solids aluminum salt-wax emulsion.

The fluid-repellent material can be applied by any suitable technique, many of which are well known in the art. Exempla- 'ry of such techniques are printing. spraying. padding and roller coating processes by means of which .the fluid-repellent material can be applied in the quantity desired to either or both sides of the outercover 16, preferably to both in order to maximize the overall effectiveness of the barrier properties. If the application can only be made to one side of the outercover 16. it is preferably made to the side which is outermost when the napkin 10 is assembled. i.e.. the outer side. The reason for this preference is that it has been found to produce an outercover 16 somewhat more resistant to lateral surface spreading of menses in use than outercovers 16 to which the fluid-repellent material is applied to the inner side.

As shown in FIG. I, the treated

areas

22 and 24 overlie the side edges and the side marginal portions of the top face of pad 12 and extend outwardly along the sides of

end extensions

18 and 20, However, it is not necessary that the sides of

end extensions

18 and 20 be treated with the fluid-repellent material and this is shown as a preferred embodiment since it enhances the quality and rate of manufacture. Therefore, if desired, the treated

areas

22, 24 could be limited to those directly aligned with the pad and the benefits of the present invention as will be realized although at some disadvantage insofar as convenience of manufacture is concerned.

FIG. 3 illustrates a fragment of a continuous web W from which the outercover I6 is constructed and the arrangement of continuous treated

areas

22, 24 thereon. In a device sized as indicated previously. the 6% inch wide web W can have treated

areas

22, 24 each of which has a width of about W4 inch separated by an untreated l% inch wide area 26 substantially centered on the web. Thus,

untreated edge areas

28, 30 of 1% inch widths remain.

Reference numerals

32, 34, 36 and 38 denote the outer limits of the

areas

22, 24 and, as shown in FIG. 2, illustrate the fact that the treated

areas

22, 24 surround each side edge of the pad 12. Due to the relative sizing described, the film 14, and the treated

areas

22, 24 overlap by about five-eights inch on each side.

If expedient, the

untreated edge areas

28, 30 can be eliminated so that the treated

areas

22, 24 extend from

lines

34, 36, respectively, to the AC adjacent side edge of the web W and therefore would each have a width of about 2% inches with the outercover sized as described. An untreated central area 26, however, must always be provided to align with the top surface portion of the pad 12 adapted to be placed adjacent the vulva of the user, although it will be realized here, too, that the area 26 does not have to be continuous; preferably the area 26 is at least about 1 inch wide and has a length of at least about 3 inches so that menses flow into the pad 12 is unhampered. The maximum width of the area 26 is governed by the width of the pad 12 and by the amount of overlap of each of the treated

areas

22, 24 on the top face of the pad l2 i.e., the width of the of

areas

22, 24 overlapping the side marginal portions of the top face of pad 12.

The continuous web W can be treated as shown in FIG. 3 and fed into well-known equipment in which the assembly of the napkin components and separation of the individual lengths of outercover 16 are accomplished. Where the treated

areas

22, 24 and the untreated central area 26-of the web W are continuous, the treating and the assembly steps can be continuous and do not present registry (alignment) quality problems.

Preferably, the entirety of the

areas

22, 24 of outercover I6 are treated so that the areas are continuous in the transverse as well as longitudinal direction. However. it is feasible to have

such areas

22, 24 comprise a discontinuous series of treated parts interspersed by untreated parts. For example, the areas 22. 24 could comprise a plurality of spaced one-sixteenth inch to onerhalf inch wide longitudinal lines of treated material separated by very narrow untreated parts of material, i.e'., onesixteenth inch to one-fourth inch wide. Similarly, such treated areas could comprise wavy lines or designs of varying shape.

lf desired, a fluorescent substance can be used as an indicator for quality control so that the location of the treated areas can be ascertained in the dried web by using an ultraviolet light source. The fluorescent substance can be added to the solution containing the water repellent material and can, for example, comprise an aminocoumarin brightener such as manufactured and sold by American Cyanamid Company. New York, New York, as Calcofluor White LD. Alternatively, the indicator substance can comprise a dye which is compatible with the water repellent solution and satisfactory for use in sanitary products. Such a dye can be selected from a great number of such substances known to those skilled in the art. The latter form of indicator substance, of course, will be visible to the eye.

In use, the end extensions 18 and of the napkin of this invention can be fastened to a sanitary belt with the untreated area 26 adjacent the vulva and thus positioned to receive the flow of menses. The fluid penetrates the outercover 16 through its thickness in area 26 and is absorbed by pad 12. If the material comprising the outercover l6 permits wicking, some of the menses will be carried outwardly towards the side edges by such action. In addition, some of the fluid received by the pad 12 will spread outwardly to its side edges. Because of the fluid repellency of the treated

areas

22, 24 however, fluid within the pad 12 and wicking within areas 26 will be prevented from penetrating the treated areas and, in addition, flow over the top of treated

areas

22, 24 will be resisted, whereby the sides of the napkin will be free of menses on its outer surface. At the same time, due to the porosity of the outercover 16 along the treated

areas

22, 24 the body-contacting portions will not prevent the circulation of air therethrough and so the napkin will feel comfortable to the user. The effectiveness of the treated outercover 16 in the prevention of penetration of the treated areas by fluid withing the pad (i.e., squeez-out) is reduced with increasing porosity as, for example, in the case of the use of an apertured nonwoven. However, in other respects the apertured nonwoven would be entirely satisfactory.

The following examples illustrate the treatment of the areas 22, 24' of the web W of the present invention with compounds of a fluid-repellent material. The web W referred to is of the line-bonded rayon nonwoven type of material described and has a width of 6% inches, the treated

areas

22, 24 of which are sized and located as set forth above. Following treatment of the web W as described in the examples the individual outercovers 16 are cut to length and the pad 12, film l4 and outercover 16 are assembled in the relationship previously recited or illustrated and the outercover l6 overlap attachment effected by gluing. The completed napkins of the present invention are then tested in actual use by women during their menstrual periods.

EXAMPLE I The web W is drawn at substantially constant speed through a set of nip rolls, one of which is covers about the portions of its periphery corresponding with the

areas

22, 24 with a felt material wetted by a spray delivering a solution of Dow Coming C-2-05 l5 water-repellent and lsopar G in which the hydrophobic polymer (silicon) is present in an amount of about 50 percent by weight. The rate of spray, and therefore the saturation of the felt material, and the pressure exerted by the nip rolls are adjusted to deposite between about 0.06 to about 0.15 grams per square foot of water repellent material on the areas of the web contacted by the felt material. The lsopar G solvent is removed by passing the web through a drying tunnel in which the continuous (both transversely and longitudinall treated

areas

22, 24 are ex osed to temfperatures of from a out F. to about 200 F. or a time su fictent to evaporate the solvent. The treated areas are found to have an AATCC spray rating of l 00 and are sufficiently porous to permit air circulation therethrough. i.e.. possess the property of breathability. Following cutting the napkin I0 is assembled with the outercover l6 oriented so that the side thereof which was contacted by the felt material is outermost. The treated areas are 1% inch apart in the vulva-contacting area of the napkin l0 and overlie about one-half inch wide side marginal portions of the top face of the pad 12. The assembled napkins 10 are compared in use with napkins identical except for the treatment of the outercover with the fluid-repellent material and it is found that the napkins 10 of the present invention reduce the incidence of smearing and side-soiling, promote longitudinal fluid distribution and increase the effective capacity of the absorbent material (i.e., the capacity of the napkin before failure occurs in use).

Similarly good results are achieved when Hypel water repellent finish and Aridex L concentrated renewable water repellent are each substituted for the above Dow Corning C-2-0510 water repellent solution and the apparatus adjusted to deposit between about 0.10 to about 0.30 grams of the aluminum salt-wax repellent materials per square foot of areas of the web contacted by the felt material.

EXAMPLE [I The web is treated by means of a two station, over and under, reverse printing flexographic press, the structure and operation of which is well known in the art. For this particular treatment the rubber print plates at each station are smooth faced, a width of 1% inch and are spaced about 1% inch. The repellent material applied at each station comprises Cyanasize 400 (a 6 percent aqueous emulsion) to which Calcofluor White LD has been added as an indicator substance in quantities of 200 ppm, based on resin solids. The apparatus is adjusted to apply between about 0.05 to about 0.15 grams of fluid-repellent material per square foot of surface printed at each station as the web is fed through. After drying as set forth in Example 1, and assembling into sanitary napkins 10, the napkins 10 are tested by comparing the same with similar napkins, the outercovers of which are not so treated. The results of this test indicate that the napkins 10 of the present inventionoutperform the similar but untreated napkins, in the manner described in Example 1.

Many modifications of the above invention may be used and it is not intended to hereby limit it to the particular embodiments shown or described. The terms used in describing the invention are used in their descriptive sense and not as terms of limitation, it being intended that all equivalents thereof be included within the scope of the appended claims.

We claim:

1. In a sanitary napkin comprising an absorbent pad enwrapped within a fluid-pervious outercover constructed of absorbent material, the improvement which comprises said outercover having areas thereof treated with a fluid-repellent material, said fluid-repellent material containing a fluorescent indicator substance said areas overlying the said side edges and side marginal portions of the top face of the said pad and being spaced apart at least in the area of the napkin adapted to engage the vulva of the user, said treated areas of said outercover being porous whereby to pennit air circulation therethrough and having an AATCC spray rating of about I00, as determined by AATCC Standard Test Method 2211964.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated February 2, 1971 Patent No. 3,559,649

Inventor) Martin Grad and Darrel D. Kokx It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

" Column 2, line 40, "strike-through should read strikethrough by-;

line 52, "l or 1/2" should read-attachment or other-,-

line 53, delete "1/2".

Column 3, line 7, after "preferably" insert -about--; line 61, "he" should read --by-; line 62, "Product" should read -product--.

Column 4, line 48, delete "AC" Column 5, line 40, "squeez-out" should read -squeeze out- 7 line 61, "covers" should read --c6vered--; line 64, "0-2-0515 should read --C2-05lO-; line 65, "silicon" should read -silicone--; line 68, "deposite" should read deposit Column 6, line 35, after "spaced" insert -by--;

line 36, "repellent" should read -fluid repellent-.

Signed and sealed this 8th day of June 1 971 (SEAL) Q Attest:

EDWARD M.FI.ETOHER,JR.

| Attesting Officer WILLIAM E. SCHUYLER, JR Commissioner of Patents