DE102010051078A1 - Fiber-containing fabric with pH-dependent decomposability and process for its preparation - Google Patents

Abstract

The present invention relates to a fiber-containing flat structure which has a pH-dependent disintegration capacity, the flat structure containing at least two binders, at least 1 binder A having a pH-dependent stability and at least 1 binder B having a pH-independent stability wherein the binder A is stable at a pH value of less than or equal to 6.4 and is not stable at a pH value from a range of 6.9 or higher, and also a method for producing the fiber-containing sheet-like structure and its use .

Description

The present invention relates to a fibrous sheet having a pH-dependent disintegratability, wherein the sheet contains at least two binders, wherein at least one binder A has a pH-dependent stability and at least one binder B a pH-independent stability wherein the binder A is stable at a pH of less than or equal to 6.4 and is not stable at a pH in the range of 6.9 or higher, and also a process for producing the fiber-containing sheet and its Use.

Pre-moistened toilet tissue or skin wipes, short wet wipes, have long been known in the art and may be made from paper or paper products that have been treated to improve their wet strength. Therefore, after being introduced into water, for example, in the toilet water, these products have a longer shelf life compared with dry comparative products which have not been increased in their wet strength. Due to the high wet strength wet wipes disintegrate after introduction into water in general only after a long time, so that they can contribute to the formation of pipe blockages and must be separated in the sewage treatment plant before the actual cleaning of the water.

Numerous approaches are known from the prior art to increase the disintegration ability of pre-moistened fiber wipers after introduction into water.

The U.S. Patent 5,629,081 describes a disintegratable wet wipe prewetted with a solution of 0.1-0.9 wt.% boric acid and 5-8 wt.% of an alkali metal bicarbonate, in which the fibers are bonded by a binder containing polyvinyl alcohol. Disadvantageously, the production of this product is very expensive.

From the U.S. Patent 5,384,189 is a water-breakable web is known in which the fibers are bound by a water-soluble binder based on unsaturated carboxylic acids and carboxylic acid esters. Some of the carboxylic acid contained in the binder is present as a salt, so that the binder is soluble in tap water, but not in an aqueous solution containing at least 0.5% by weight of a neutral, monovalent inorganic salt. This process is complicated in the production.

The U.S. Patent 4,755,421 discloses a nonwoven fabric made by water-jet needling of cellulosic fibers and regenerated cellulosic fibers which is to be broken up in the waste water by stirring or longer residence time. However, the nonwoven fabric disadvantageously has low mechanical durability even when used.

Another method for producing a water-breakable cloth is in U.S. Patent 5,667,635 described in which three layers of tissue paper are embossed together only at the corners and the two outer layers to control by additional local application of a wet agent, the disintegration of the cloth in an aqueous system. Disadvantageously, the production of this product is very expensive.

From the DE 28 17 604 C2 EP 0 916 031 A discloses a pre-moistened, flushable wipe comprising a web of fibrous materials and an adhesive binder distributed throughout the web bonding the nonwoven web of the web, the adhesive binder consisting essentially of an acid-insoluble / alkali-soluble acidic polymer which is weak in an acidic liquid the bond between the fibers of the nonwoven is stable.

The disadvantage here, however, is that the pH should be kept between 2 and 5, which may cause irritation of the skin at this pH. In addition, over time a disintegration of this wipe, which impairs further usability occurs.

On the one hand, the known water-dissipative wet wipes have the disadvantage that they contain partially aggressive, food-problematic or even allergenic and inflammatory substances in order to achieve sufficient mechanical wet strength. On the other hand, however, the wet strength is sometimes so greatly reduced that, disadvantageously, the integrity of the wet wipe is already destroyed by a low mechanical load, which may occur, for example, during use.

The object of the present invention is therefore to provide a fibrous sheet which, on the one hand, has sufficient mechanical wet strength in use and, on the other hand, after Incorporation in water should have sufficient disintegration, so that it does not come for example to block the toilet tube or in the sewage treatment plant before the actual cleaning of the wastewater must not be removed.

Another object of the present invention is to provide a water-breakable fiber structure which is easy and inexpensive to manufacture.

The object is achieved by the provision of a fibrous sheet having a pH-dependent decomposability, wherein the sheet contains at least two binders, wherein at least 1 binder A is a pH-dependent stability and at least one binder B is a pH independent Stability, wherein the binder A is stable at a pH of less than or equal to 6.4 and is not stable at a pH in the range of 6.9 or higher.

• (a) Bereitstellen von Fasern,
• (b) Ablegen der Fasern auf einer Aufnahmefläche unter Erhalt eines Faserbetts,
• (c) Verdichten des Faserbettes, unter Erhalt eines verdichteten Fasernbettes, wobei in den Schritten (a) und/oder (b) und/oder (c) und zwischen den Schritten (a), (b) oder (c) und/oder nach Schritt (c) wenigstens 1 Bindemittel A, das eine pH-Wert abhängige Stabilität aufweist, und wenigstens 1 Bindemittel B, das eine pH-Wert unabhängige Stabilität aufweist, aufgebracht wird, wobei das wenigstens eine Bindemittel A bei einem pH-Wert von kleiner oder gleich 6,4 stabil ist und bei einem pH-Wert aus einem Bereich von 6,9 oder höher nicht stabil ist.

Furthermore, the object is achieved by the provision of a method for producing a fibrous sheet, the method comprising the following steps:

• (a) providing fibers,
• (b) depositing the fibers on a receiving surface to obtain a fibrous bed,
• (c) compacting the fiber bed to obtain a compacted fiber bed, wherein in steps (a) and / or (b) and / or (c) and between steps (a), (b) or (c) and / or after step (c) at least 1 binder A, which has a pH-dependent stability, and at least 1 binder B, which has a pH independent stability, is applied, wherein the at least one binder A at a pH of less or 6.4 is stable and is not stable at a pH in the range of 6.9 or higher.

Furthermore, the object is achieved by the use of a fibrous sheet as a hygiene article, in particular as a wet wipe or moist toilet paper.

Preferred embodiments of the invention are specified in the subclaims.

The at least one binder A may be different binders, for example 2, 3, 4 or more binders.

The at least one binder B may be different binders, for example 2, 3, 4 or more binders.

Surprisingly, the inventors have found that by using at least 1 binder A which has a pH-dependent stability and at least 1 binder B which has a pH-independent stability, it is possible to provide a fibrous sheet, which, on the one hand, has sufficient mechanical wet strength and does not lose its integrity under brief mechanical stress, for example due to friction on the skin. On the other hand, the fibrous sheet according to the invention after introduction into water has a sufficient decomposability in water, so that it can not lead to blockages after disposal via the toilet or in the sewage treatment plant before the actual purification of the wastewater does not need to be removed. In addition, the fibrous sheet according to the invention has sufficient mechanical stability even after prolonged storage.

According to the invention, the fibrous sheet contains at least 1 binder A, which has a pH-dependent stability.

After incorporation of the fibrous sheet in water having a pH at which the stability of the binder A changes, the stability of the binder A is lost, thereby weakening or destroying the structural integrity of the fibrous sheet. The solubility behavior and / or the degree of ionization of the binder A may change.

Due to the loss of stability of the at least one binder A, the at least one binder A can no longer, preferably no longer, combine the fibers of the fibrous sheet together with sufficient mechanical stability.

As a result, fiber structures and / or connections between the fibers within the fibrous sheet can be widened, loosened, weakened, stretched and / or destroyed. By mechanical influences, for example due to the flow influences occurring in wastewater, the structural integrity of the fibrous sheet is weakened, preferably destroyed.

According to EC Directive 83/98 (CELEX No: 39810083) "On the quality of water intended for human consumption" (98/83 / EC) drinking water should have a pH in the range of 6.5 to 9.5 exhibit. For example, the pH of the wastewater used in biological wastewater treatment should be in the range of 6.0 to 8.0 so as not to hinder the purification process.

As a rule, the pH of wastewater is in the range of 7.0 to 8.5.

The term "stability of the binder" is understood according to the invention as a binder, the same or different substances, preferably fibers to connect together.

The term "pH-dependent stability of the binder" is thus understood according to the invention to mean a pH-dependence of the function as a binder to bind identical or different substances, preferably fibers, to one another.

According to the invention, the at least one binder A is at a pH of less than or equal to 6.4, preferably at a pH of less than or equal to 6.2, more preferably at a pH of less than or equal to 5.9, in able to bind identical or different substances, preferably fibers, and thus is "stable" in the sense of the invention.

In another preferred embodiment, the at least one binder A is at a pH of from 4.0 to 6.4, preferably from 4.5 to 6.3, more preferably from 5.1 to 6.2, further preferably from 5.2 to 6.1, more preferably from 5.3 to 6.0, more preferably from 5.4 to 5.8, more preferably from 5.5 to 5.7, stable in the context of the invention.

After application and setting of at least 1 binder A on the fibrous sheet, the fibers of the fabric are at least partially, preferably completely, interconnected by the at least one binder A.

When introducing the fibrous sheet into water having a pH greater than or equal to 6.9, the at least one binder A used according to the invention loses its function as a binder at least partially, preferably completely, for example, the contact between the fibers of the fabric and the at least one binder A can be at least partially, preferably completely, interrupted or the at least one binder A can at least be split.

The at least one binder A can be bonded to the fibers of the fabric according to the invention by way of hydrogen bonds, for example. When the fibrous sheet of the invention is introduced into water having a pH of greater than or equal to 6.9, the hydrogen bonds may be eliminated and the bonds between the at least one binder A and the fibers of the sheet of the invention are at least partially, preferably completely dissolved, whereby the at least one binder A can be detached from the fibers, for example.

The at least one binder A may, for example, also be covalently bonded to the fibers of the fabric. In addition, covalent bonds and hydrogen bonds may occur between molecules of the at least one binder A and the fibers of the inventive sheet.

When introducing the fibrous sheet of the invention in water having a pH of greater than or equal to 6.9, it may by one or more chemical reaction (s), for example by hydrolysis, for example, for cleavage of at least 1 binder A come, which hereinafter Can no longer connect fibers of the fabric of the invention.

• (a) eine Zunahme der Löslichkeit in Wasser erfährt und/oder
• (b) eine Abnahme der Diffusionsdichte erfährt und/oder
• (c) eine Beschleunigung der Lösungskinetik erfährt und/oder
• (d) eine Abnahme der mechanischen und/oder chemischen Stabilität erfährt.

The pH-dependent stability of the at least one binder A leads, for example, to the fact that the at least one binder A is exposed to a change in the pH in the surrounding liquid to which the at least one binder A is exposed.

• (a) experiences an increase in solubility in water and / or
• (b) undergoes a decrease in diffusion density and / or
• (c) experiences an acceleration of the dissolution kinetics and / or
• (d) undergoes a decrease in mechanical and / or chemical stability.

As a result, preferably binder 1 loses its function as a binder at least partially, preferably completely, and is therefore "not stable" in the sense of the invention. The fibers of the sheet according to the invention may subsequently be at least partially, preferably not more, connected by the at least one binder A.

According to the invention, the at least one binder A is at a pH of a range of 6.9 or higher, preferably at a pH of 7.0 or greater, more preferably at a pH of 7.1 or greater preferably at a pH of 7.2 or greater, more preferably at a pH of 7.3 or greater, more preferably at a pH of 7.4 or greater, unstable, and therefore incapable of , same or different substances, preferably fibers, to connect together.

In a further preferred embodiment, the at least one binder A is at one at a pH from a range of 7.0 to 9.5, preferably from 7.1 to 9.1, more preferably from 7.2 to 8.8 , more preferably from 7.3 to 8.5, more preferably from 7.4 to 8.3, further preferably from 7.5 to 8.1, not stable in the sense of the invention.

Preferably, the pH values mentioned in the present application are measured in water under standard conditions (25 ° C., 1013 mbar).

In a further preferred embodiment of the present invention, the at least one binder A has a pH-dependent stability at a temperature of less than or equal to 50 ° C, preferably less than or equal to 42 ° C, more preferably less than or equal to 37 ° C on ,

According to a further preferred embodiment, the pH-dependent stability of the at least one binder A does not depend on the ionic strength of the water.

As a result, the structural integrity of the fibrous sheet according to the invention after introduction into water having a pH of greater than or equal to 6.9, preferably at a pH in the range of 7.0 to 9.5, at least partially weakened, preferably completely destroyed, even if a higher ion concentration is present in the wastewater, for example, by the entry of road salt into the wastewater or salty meltwater in winter.

Preferably, the stability of the at least one binder A used according to the invention is independent of the ionic strength at a pH of less than or equal to 6.4, preferably at a pH in the range of 4.0 to 6.4, more preferably in one pH from a range of 5.1 to 6.4. As a result, the at least one binder A used according to the invention has sufficient stability, for example at a pH of less than or equal to 6.4, even in the absence of ionogenic substances.

In a preferred embodiment, the at least one binder A is in water at a pH of less than or equal to 6.3, preferably less than or equal to 6.2, preferably less than or equal to 6.0, more preferably less than or equal to is equal to 5.5, substantially stable, preferably stable, within the meaning of the invention.

In a further preferred embodiment, the fibers of the fabric lose in water at pH values above at least 7.6, preferably above at least 7.5, preferably above at least 7.4, more preferably above at least 7.2, more preferably above at least 7.0, their cohesion at least partially or completely.

Materials which can be used as coating material in the context of the invention are any inorganic and / or organic substances and / or substance mixtures, but in particular polymers, preferably homopolymers and / or copolymers, and / or polymeric composites having a pH-dependent solubility and / or have a pH-dependent dispersibility and / or a pH-dependent binding ability to fibers of the fibrous sheet according to the invention.

In a preferred embodiment, polymers, preferably homopolymers and / or copolymers, which can preferably be used from aqueous dispersion, can be used as the coating material.

For example, for reasons of flammability and / or toxicity, organic solvents are disadvantageous in the production of fibrous structures. Aqueous dispersions are characterized, for example, by easy handling and the substantial avoidance of toxicologically problematic substances.

The principle of a pH-dependent solubility and / or a pH-dependent dispersibility and / or a pH-dependent binding ability is generally based on a protonation or deprotonation of functional groups of the polymer molecules, which changes, for example, their charge state accordingly. Preferably, the polymer has a stable charged state at a certain pH and is soluble and / or dispersible in water. In contrast, the polymer precipitates, for example, in the uncharged state at a different pH and / or is bound to fibers of the fibrous sheet of the invention.

For example, the at least one binder A may be present at a certain pH, for example less than or equal to 6.4, preferably at a pH in the range of 4.0 to 6.4, bound to fibers of the inventive sheet and is thus not soluble and / or not dispersible.

At a pH of greater than or equal to 6.9, preferably at a pH in the range of 7.0 to 9.5, the at least one binder A is present at least partially, preferably not more, bound to fibers of the fabric and thus is at least partially, preferably completely, soluble and / or dispersible.

In the context of the present invention, it is preferred that the binder A used according to the invention comprises homopolymer and / or copolymer which has a lower water solubility and / or dispersibility at a lower pH than at higher pH values or even at a lower pH Value are water insoluble.

In a further variant, the binder A used according to the invention is in water at a pH above at least 7.5, preferably above at least 7.4, preferably above at least 7.2, more preferably above at least 7.1 preferably above at least 7.0, partially or completely soluble.

In a further preferred embodiment, the binder A used according to the invention is predominantly insoluble in water at a pH below 6.3, preferably below 6.1, more preferably below 5.8, even more preferably below 5.6, preferably completely insoluble.

Polymers with pH dependent solubility are known in the art. For example, acid-insoluble polymers are usually based on derivatives of polyacrylic acid, which is present in undissoziierter and therefore insoluble form in the acidic region, but in the alkaline range, for example at a pH of 8.0 is charged and goes as a polyanion in solution.

Polymers of similar type which have a pH-dependent solubility are advantageous for use as binder A. Preferably, the at least one binder A is substantially stable in the acidic pH range, preferably stable, in the sense of the invention, but dissolves at least partially, preferably completely, in the neutral to alkaline pH range, or becomes at least partially, preferably completely dispersible ,

According to a preferred embodiment, the at least one binder A comprises polyacrylic acid and / or derivatives of polyacrylic acid, which at pH values above at least 6.9, preferably above at least 7.0, preferably above at least 7.1, more preferably above at least 7.2, more preferably above at least 7.3, more preferably above at least 7.4, even more preferably above at least 7.5, more preferably above at least 8.0, is present as polyanion and / or goes into solution ,

Preferred substances in the context of the present invention are acidic polymers, preferably homopolymers and / or copolymers which contain carboxylic acid and / or sulfonic acid and / or sulfonamide groups, more preferably carboxylic acid groups.

The polymers may, for example, be homopolymers and / or copolymers of carboxylic acids with esters, alkanes and / or alkenes.

Preferably, suitable carboxylic acid homopolymers and / or carboxylic acid copolymers have an acid number of from 30 to 250 mg KOH / g dry polymer, preferably from 50 to 210 mg KOH / g dry polymer, more preferably from 60 to 200 mg KOH / g dry polymer, on.

Suitable methods for determining the acid number of polymers are known in the art. The acid number can be determined, for example, according to Ph. Eur. 6.5 (2009) Chapter 2.2.20 "Potentiometric titration".

As monomers it is possible to use unsaturated carboxylic acids, for example aliphatic, unsaturated monocarboxylic acids having 3 to 7 carbon atoms and / or aliphatic, unsaturated dicarboxylic acids having 4 to 8 carbon atoms and / or aromatic carboxylic acids having 6 to 10 carbon atoms.

Suitable monomers are, for example, acrylic acid, methacrylic acid, maleic acid, phthalic acid or derivatives of these compounds. Suitable polymers are, for example, carboxylalkyl methacrylate copolymers, acrylic acid and / or methacrylic homo- and copolymers, polyvinyl acetate phthalates (PVAP) and mixtures thereof.

Also suitable carboxylic acid homopolymers are, for example, "low molecular weight" polyacrylic acids, polymethacrylic acids, polymaleic acids and copolymers thereof with a molecular weight of at least 1000 to 16000 g / mol.

In a preferred embodiment, the at least one binder A comprises carboxylalkyl methacrylate copolymers, preferably methyl methacrylate and / or ethyl acrylate and / or methyl acrylate-methacrylic acid copolymers, wherein preferably the ratio of the free carboxyl groups to the ester groups is greater than or equal to 1: 2 , preferably from a range of 1: 2 to 1:15, more preferably from a range of 1: 2 to 1:10.

Suitable carboxyalkyl methacrylate copolymers, for example, by the company Evonik Industries AG (Essen, Germany) under the brand name EUDRAGIT ^®, such as EUDRAGIT ^® S100 or EUDRAGIT ^® FS 30 D.

Other suitable carboxyalkyl methacrylate copolymers are, for example, by the company Colorcon (West Point, PA, USA) under the trade name Opadry ^® Enteric-94 series Methacrylic Acid Copolymer (methacrylic acid-methyl methacrylate (1: 1) copolymer) or Opadry ^® Enteric-95 series Methacrylic Acid Copolymer (methacrylic acid-methyl methacrylate (1: 2) copolymer).

The Eastman Chemical BV (Rotterdam, Netherlands) sells suitable cellulose acetate phthalate under the brand name Eastman CAP ^® or Aquateric ^®.

Other suitable polymers are marketed under the brand name Carbopol ^® from Lubrizol (Wickliffe, OH, United States). Preferably, these are Carbopol ^® 71 G, carbopol ^® 971P NF, Carbopol ^® 974 P NF, Carbopol ^® 934 P NF1, Carbopol ^® 5984 EP or Carbopol ^® 980 NF, where they are homopolymers of acrylic acid with Allyl succrose or allyl pentaerythritol are crosslinked.

Also binders which are at least partially made of an ampholytic polymer, preferably a copolymer of basic monomers such as dialkylaminoalkyl (meth) acrylates with substituted and / or unsubstituted acrylic acids and / or (meth) acrylic acids and / or their esters with aliphatic C 1 -C 8 -alcohols, preferably methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, propanol, hexanol, heptanol or octanol exist, represent a preferred embodiment of the invention.

For the application, in addition to the thermodynamic solubility and the dissolution kinetics of at least 1 binder A in a liquid surrounding the binder, preferably water, or the Decrease in mechanical stability of importance. The solution kinetics of the coating materials used according to the invention can be pH-dependent down to the alkaline range.

In a further embodiment of the present invention, polymers are used which have a pH of between 7.0 and 9.5, preferably from 7.1 to 9.2, preferably from 7.3 to 8.7, more preferably from 7 , 4 to 8.5, become highly water-soluble and are poorly or not at all soluble at lower pH values than at the higher pH values. Suitable polymers preferably contain acidic groups, for example carboxylic acid and / or sulfonic acid and / or sulfonamide groups, more preferably carboxylic acid groups.

By "poorly or not at all soluble" is understood according to the invention that the binding capacity of the binder does not deteriorate significantly or not.

At lower pH values, the molecule is preferably in the uncharged state and is thus insoluble. As a rule, the transition takes place depending on the pKa value of the acidic groups and also depending on their density along the polymer chain. Suitable binders A therefore also include polymers in which the transition point lies in a range between pH 6.9 and 9.0, preferably between pH 7.2 and 8.5, more preferably between pH 7.5 and 8.1.

The term "transition point" is understood according to the invention to mean the pH at which the binder loses its function as a binder, identical or different substances, preferably fibers, with each other, at least partially, preferably completely.

The transition point of a polymer suitable for the purposes of the present invention is dependent on the pKa value of the functional groups of the polymer, the state of charge of the polymer only very slightly changing in the range of relatively high pH values. Therefore, it is advantageous if the solubility of the polymer is critically affected with a small change in the state of charge of the polymer. The polymer preferably has such a hydrophilicity that it becomes insoluble in a completely uncharged state, but becomes soluble when already slightly charged, for example by deprotonation of functional groups.

For example, acidic groups, for example carboxyl groups, are converted to a charged state by deprotonation of the functional group, while basic groups, for example amino groups, are converted to a charged state by protonation of the functional group.

Copolymers of acidic monomers, water-insoluble monomers and, if desired, water-soluble monomers are suitable according to the invention. Suitable acidic monomers are, for example, acrylic acid, methacrylic acid, phthalic acid or succinic acid. As water-insoluble monomers are esters of acrylic acid or methacrylic acid with alcohols having 1 to 8 carbon atoms, in particular the methyl esters, ethyl esters, n-propyl, i-propyl, butyl or 2-hexyl ethyl ester used. Water-soluble monomers which are preferably used are substances such as acrylamide, methacrylamide, vinylpyrrolidone or hydroxyethyl acrylates or methacrylates.

A suitable process for the preparation of polymers having pH-dependent solubility comprising sulfonamide groups is described, for example, in US Pat U.S. Patent 6,103,865 described.

• – Copolymerisation eines Monomers mit basischer Funktion mit einem hydrophileren Monomer. Durch das Einbauverhältnis der jeweiligen Comonomeren wird der Umschlagspunkt beeinflusst.
• – Hydrophilierung des basische Gruppen tragenden Polymers durch eine polymeranaloge Umsetzung. Durch den Modifikationsgrad wird der Umschlagspunkt beeinflusst.

To adjust the hydrophilicity, the following measures can be taken:

• - Copolymerization of a monomer with a basic function with a hydrophilic monomer. The incorporation ratio of the respective comonomers influences the transition point.
• Hydrophilization of the basic group-bearing polymer by a polymer-analogous reaction. The degree of modification influences the turnover point.

In a further preferred embodiment, the at least one binder A has a molecular weight of at least 1000 g / mol, more preferably from a range of at least 5000 g / mol to 6000000 g / mol, more preferably from a range of 12000 g / mol to 4000000 g / mol, more preferably from a range of 40000 g / mol to 3500000 g / mol.

In a further variant, the at least one binder A has a molecular weight from a range of 40,000 g / mol to 400,000 g / mol, more preferably from a range of 100,000 g / mol to 350,000 g / mol, more preferably from a range of 150,000 g / mol to 300,000 g / mol, on.

According to the invention, the fiber-containing fabric further contains at least 1 binder B, which has a pH-independent stability.

The function as a binder of the binder B used according to the invention, identical or different substances, preferably fibers, to connect with each other, thus has no pH dependence on.

In a preferred embodiment of the present invention, the binder B used according to the invention has a pH-independent stability at a temperature of less than or equal to 50 ° C, preferably less than or equal to 42 ° C, more preferably less than or equal to 37 ° C.

Regardless of the pH of the surrounding solution, the binder B used according to the invention is therefore able to bind identical or different substances, preferably fibers, to one another.

Preferably, the at least one binder B has a pH independent stability in the pH range that may occur in the wastewater, preferably between a pH of 4.0 to 10.0, more preferably between a pH of 4 , 5 to 9.5.

In a preferred embodiment of the invention, the at least one binder B is selected from the group consisting of polyalkanes, polyamides, polyimides, polyamide-imides, polyesters, polyethers and polyureas.

In a further preferred embodiment of the invention, the at least one binder B is selected from the group consisting of polyethylene, polypropylene, polyesters, homopolymers of esters of acrylic acid with alcohols having 1 to 8 carbon atoms, homopolymers of esters of methacrylic acid with alcohols with 1 to 8 C atoms, copolymers of esters of acrylic acid and methacrylic acid with alcohols having 1 to 8 carbon atoms, copolymers of esters of unsaturated carboxylic acids having 3 to 8 carbon atoms with alcohols having 1 to 8 carbon atoms, styrene-butadiene copolymers , Styrene-acrylate copolymers, ethylene-vinyl acetate copolymers, and mixtures thereof.

Further preferred esters of acrylic acid and / or methacrylic acid with alcohols having 1 to 8 C atoms are the methyl esters, ethyl esters, n-propyl esters, i-propyl esters, butyl esters and / or 2-hexyl ethyl esters.

In a particularly preferred embodiment, the binder B used according to the invention is an ethylene-vinyl acetate copolymer.

In a further preferred embodiment of the present invention, the at least one binder B has a molecular weight of at least 1000 g / mol, more preferably from a range of at least 5000 g / mol to 6000000 g / mol, more preferably from a range of 12000 g / mol to 4000000 g / mol, more preferably from a range of 40000 g / mol to 3500000 g / mol.

The inventors have surprisingly found that a fibrous sheet having pH-dependent disintegration capability can be provided when the sheet contains at least two binders having different pH dependence on stability, wherein at least one binder A has a pH-dependent stability and at least 1 binder B has a pH-independent stability.

By means of the combination of the at least two binders used according to the invention, it is possible to provide a fiber-containing sheet which has sufficient mechanical wet strength under brief mechanical stress, for example due to friction on the skin.

In a preferred embodiment of the present invention, the fibrous web is wet. More preferably, the fiber-containing fabric has a moisture content from a range of 100 wt .-% to 250 wt .-%, more preferably from 150 wt .-% to 200 wt .-%, in each case based on the total weight of the fibrous sheet in the dry state.

In a further preferred embodiment, the fibrous sheet comprises an aqueous solution having a pH of less than or equal to 6.4, preferably having a pH of less than or equal to 6.1, preferably having a pH of less than or equal to 5 , the ninth

According to a preferred variant, the pH of the aqueous solution is in a range of pH 4.5 to 6.4, preferably in the range of pH 4.9 to 5.9.

By the combination of two binders with different pH-dependent stability used according to the invention it is also possible to provide a fibrous sheet which has sufficient wet strength even in the partially wet, preferably wet state.

Only after introduction of the fibrous sheet in water, in particular wastewater, with a pH of 6.9 or higher, preferably with a pH of 7.1 or higher, the binder according to the invention A is no longer stable and thus can the fibers the fiber-containing fabric no longer connect.

The use of at least 1 binder B increases the mechanical wet strength under short-term mechanical stress. However, after the introduction of the fibrous sheet in water having a pH of 6.9 or higher, preferably having a pH of 7.1 or higher, at which the binder A of the invention is no longer stable, the stability of the at least sufficient 1 Binder B is not sufficient to sufficiently connect the fibers of the fiber-containing sheet.

As a result, the wet strength of the fibrous sheet of the invention decreases and the fibrous sheet is at least partially disintegrated, preferably completely.

In a further preferred embodiment, the proportion of the at least 1 binder A and at least 1 binder B is in a range from 1 wt .-% to 35 wt .-%, preferably 3 wt .-% to 30 wt .-%, more preferred from 4 wt% to 25 wt%, more preferably from 5 wt% to 20 wt%, more preferably from 6 wt% to 15 wt%, more preferably from 7 wt% % to 13 wt .-%, each based on the total weight of the dry fibrous sheet according to the invention, on.

In a further preferred embodiment, the fibrous sheet comprises at least 1 binder A in a proportion of 50% by weight to 90% by weight, preferably from 58% by weight to 88% by weight, more preferably of 61% by weight. % to 86 wt%, more preferably from 63 wt% to 84 wt%, more preferably from 65 wt% to 82 wt%, still more preferably from 67 wt% to 80 wt% -%, more preferably from 69 wt .-% to 79 wt .-%, and at least one binder B in a proportion of 10 wt .-% to 50 wt .-%, preferably from 12 wt .-% to 42 wt. -%, more preferably from 14 wt .-% to 39 wt .-%, more preferably from 16 wt .-% to 37 wt .-%, more preferably from 18 wt .-% to 35 wt .-%, more preferably from 20 wt .-% to 33 wt .-%, more preferably from 21 wt .-% to 31 wt .-%, each based on the total content of the dry binder, wherein the proportion of at least 1 binder A and the proportion of at least 1 binder B together give 100 wt .-%.

In another preferred embodiment, the total content of the binders is a binary mixture containing a binder A in a proportion of from 50% to 90% by weight, preferably from 58% to 88% by weight preferably from 61% to 86%, more preferably from 63% to 84%, more preferably from 65% to 82%, more preferably 67% by weight. from% to 80% by weight, more preferably from 69% by weight to 79% by weight, and a binder B in a proportion of from 10% by weight to 50% by weight, preferably 12% by weight. % to 42 wt%, more preferably from 14 wt% to 39 wt%, more preferably from 16 wt% to 37 wt%, still more preferably from 18 wt% to 35 wt% -%, more preferably from 20 wt .-% to 33 wt .-%, more preferably from 21 wt .-% to 31 wt .-%, each based on the total content of the dry binder.

In a further preferred embodiment, the binder B and the binder A may be used as a mixture, preferably a binary mixture, in a weight ratio (weight fraction: weight fraction) in a range from 1: 8 to 1: 1, preferably in a range from 1: 7 to 1 : 2, more preferably in a range from 1: 6 to 1: 3, in each case based on the weight fraction of the dry binder, are present.

According to a further preferred variant, the weight ratio of the binder (s) B to the binder (s) A is in a range from 1: 4 to 1: 2.

In a further preferred embodiment, the fibrous sheet according to the invention comprises further constituents, such as disintegrants, fillers, dyes or disintegrating agents with pH-dependent swelling capacity.

• a.) einen quellfähigen Kern mit wenigstens einer eine pH-Wert-abhängige Löslichkeit aufweisenden Beschichtung versehen ist und/oder
• b.) wenigstens ein Quellmittel mit pH-Wert-abhängiger Quellfähigkeit umfasst.

For example, in the fibrous sheet at least one disintegrating agent with pH-dependent swelling capability may be arranged, wherein the disintegrating agent

• a.) Is provided a swellable core having at least one pH-dependent solubility coating and / or
• b.) comprises at least one swelling agent with pH-dependent swelling capacity.

Preferably, the swellable core may be coated with at least one coating having a pH-dependent solubility.

Preferably, the swellable core and / or the swelling agent having a pH-dependent swelling agent may be present in particulate form and / or as a fiber.

The fibrous sheet of the present invention preferably contains water-dispersible fibers. In a preferred embodiment, the fibers of the sheet have a length from a range of 0.2 mm to 6 mm, more preferably from 1 mm to 4 mm, more preferably from 1.1 to 3 mm.

In this case, both natural fibers and synthetic fibers and mixtures thereof can be used.

Suitable synthetic fibers include, for example, polyester fibers, polyamide fibers, polyimide fibers, polyamide-imide fibers, polyethylene fibers, polypropylene fibers, polyvinyl chloride fibers, or mixtures thereof.

In a preferred embodiment, pulp fibers are mainly used. In addition, for example, rayon, cotton, wool, acetate, or tencel fibers can be used. In another preferred embodiment, the fibrous web comprises from 40 to about 95% by weight, more preferably from 60 to 90% by weight, of pulp fibers, each based on the total weight of the dry fibrous web of the invention.

The pulp fibers used can be obtained by a chemical pulping of plant fibers or by using recycled fibers. Preferably, both wood fibers, fibers of annual plants such as straw, bagasse, kenaf or bamboo, and mixtures thereof may be used. In addition, for example, both softwood pulp and hardwood pulp may be used, the nature of the chemical pulping used per se is not critical.

The fibers used, preferably pulp fibers, are joined together by at least 1 binder A and at least 1 binder B.

The binders used can preferably be used as binder fibers and / or as aqueous solution and / or as binder foam.

In a preferred embodiment, the fibrous sheet has 1 to 4 layers, preferably 1 to 3 layers. More preferably, the fibrous sheet is single-ply.

In a further preferred embodiment, the fibrous sheet has multiple layers, preferably 2, 3 or 4 layers, none of these multiple layers being impermeable to aqueous media.

Preferably, the fibrous sheet according to the invention has a weight per unit area in the range from 40 g / m ² to 150 g / m ² , preferably from 45 g / m ² to 80 g / m ² .

In a further embodiment, the fibrous sheet is additionally provided with at least one coating having a pH-dependent solubility.

The fibrous sheet according to the invention is preferably present as nonwoven or nonwoven material. In a further preferred embodiment, the fibers are transferred into a fibrous web by carding, wet-laying, air laying, spunbonding or meltblowing. The fiber or nonwoven web is particularly preferably formed by the airlaid process, also referred to as airlaid process, in which substantially all, preferably all, fibers are intimately mixed. Preferably, the airlaid web is then compressed or compacted.

• (a) Bereitstellen von Fasern,
• (b) Ablegen der Fasern auf einer Aufnahmefläche unter Erhalt eines Faserbetts,
• (c) Verdichten des Faserbetts unter Erhalt eines verdichteten Faserbettes, wobei in den Schritten (a), (b) und/oder (c) und/oder zwischen den Schritten (a), (b) und/oder (c) und/oder nach Schritt (c) wenigstens 1 Bindemittel A, das eine pH-Wert-abhängige Stabilität aufweist, und wenigstens 1 Bindemittel B, das eine pH-Wert-unabhängige Stabilität aufweist, aufgebracht wird, wobei das wenigstens eine Bindemittel A bei einen pH-Wert von kleiner oder gleich 6,4 stabil ist und bei einem pH-Wert aus einem Bereich von 6,9 oder höher nicht stabil ist.

The fibrous sheet according to the invention produced by a process comprising the following steps:

• (a) providing fibers,
• (b) depositing the fibers on a receiving surface to obtain a fibrous bed,
• (c) compacting the fiber bed to obtain a compacted fiber bed, wherein in steps (a), (b) and / or (c) and / or between steps (a), (b) and / or (c) and / or after step (c) at least 1 binder A, which has a pH-dependent stability, and at least 1 binder B, which has a pH-independent stability, is applied, wherein the at least one binder A at a pH Value is less than or equal to 6.4 is stable and is not stable at a pH in the range of 6.9 or higher.

The compacting of the fiber bed can take place by various methods known in the art, such as, for example, latex bonding, thermal bonding, hydrogen bonding or multi-bonding. Optionally, by calendering the thickness of the fibrous sheet can be adjusted. In a preferred embodiment, the fibrous sheet has superficial depressions and / or elevations, which may be produced by embossing, for example.

In a further preferred embodiment, in or after step (c), at least one binder A, which has a pH-dependent stability, and at least one binder B, which has a pH independent stability, applied, wherein the at least a binder A is stable at a pH of less than or equal to 6.4 and is not stable at a pH in the range of 6.9 or higher.

More preferably, in step (a) and / or during steps (b) and / or (c) at least 1 binder A and at least 1 binder B is applied as an aqueous solution and / or as a binder foam and subsequently at a temperature of greater than 100 ° C, preferably greater than 150 ° C solidified.

The application of the at least one binder A and at least one binder B can take place by means of spraying, knife coating and / or dipping.

Suitable methods of bath impregnation, foam impregnation and / or spray application are known in the art and may be used in the present invention.

The at least one binder A and the at least one binder B can be applied separately on the same side or on different sides of the fibrous sheet.

The application of the binders A and B may be sequential, wherein the order of binder application is variable, or carried out simultaneously.

The application of the binders A and B may also be effected in the form of a mixture of at least 1 binder A and at least one binder B on one side or on both sides of the fibrous sheet.

In a further preferred embodiment, in step (a) and / or during steps (b) and / or (c) the at least one binder B is added as binder fiber and subsequently at a temperature of greater than 100 ° C, preferably greater than 135 ° C melted. As a rule, the melting temperature does not exceed 160 ° C.

In this preferred embodiment, the binder B when used in the form of a binder fiber comprises or consists of at least two polymer components with different melting points, preferably polyethylene and / or polypropylene on the one hand and polyester on the other hand. Preferably, the binder fiber has a core-shell structure, wherein at least one first polymer component having a melting point S1, for example polyester, is present as a fiber core and at least one second polymer component having a melting point S2, for example polyethylene and / or polypropylene, is present as a fiber cladding S1> S2 is.

Preferably, the binder fiber has a length between 1.0 and 7.0 mm, preferably 2.0 and 6.0 mm, more preferably up to 3.0 mm.

In a further preferred embodiment, at least 1 binder B is applied both as a binder fiber and as an aqueous solution and / or as a binder foam.

In a further preferred embodiment, the fibrous sheet according to the invention comprises or consists of a pulp web, wherein the pulp web 65 to 99 wt .-% pulp fibers having a length from a range of 0.2 mm to 6 mm, more preferably from 1 mm to 4 mm , more preferably from 1.1 to 3 mm, and a binder content of 1 to 35 wt .-%, each based on the total weight of the dry sheet, wherein the binder content of at least 1 binder B, optionally partially or completely in the form of a binder fiber, and at least 1 binder A comprises or consists of, wherein the binder A is a proportion of 50 wt .-% to 90 wt .-%, preferably from 61 wt .-% to 84 wt .-%, more preferably of 65 wt. % to 79 wt .-%, and the binder B is a proportion of 10 wt .-% to 50 wt .-%, preferably from 16 wt .-% to 39 wt .-%, more preferably from 21 wt .-% to 35 wt .-%, each based on the total content of the dry Bin demittel.

In a further preferred embodiment, the fibrous sheet according to the invention comprises or consists of a pulp web, wherein the pulp web 79 to 93 wt .-% pulp fibers of a length from a range of 1 mm to 4 mm, more preferably from 1.1 to 3 mm, and at least 1 binder B, optionally partially or completely in the form of a binder fiber, in a proportion of 2 to 6 wt .-% and at least 1 binder A in an amount of 5 to 15 wt .-%, each based on the total weight of the dry sheet ,

After the setting of the at least 1 binder A and the at least one binder B, optionally at least one lotion can be applied to the fibrous sheet according to the invention. The application of at least 1 lotion can be done by means of watering and / or spraying.

Preferably, the fibrous sheet according to the invention has a wet strength, determined according to DIN 54540-8 , from a range of 5 to 30%, preferably 8 to 20%, of the dry strength.

Surprisingly, the sheet according to the invention, in spite of its wet strength, has sufficient water-decomposing capability to decompose in the wastewater. It is preferred that the wet strength of the fibrous sheet, determined according to DIN 54540-8 by at least 50%, preferably of at least 60%, decreases, measured after one hour underwater storage at a temperature of 25 °.

In a preferred embodiment, the fibrous web is wet. More preferably, the fibrous sheet contains a lotion having a pH of less than or equal to 5.5.

Preferably, the lotion has a pH in the range of 4.0 to 6.0, preferably 5.0 to 5.6, and is therefore pH neutral with respect to the pH of healthy skin.

According to the invention, the term "lotion" is understood to mean a liquid aqueous or aqueous-alcoholic preparation or an oil-in-water emulsion or a water-in-oil emulsion.

In a further preferred embodiment, the lotion further comprises at least one preservative which can afford, for example, the protection of microorganisms in long-term storage. It is preferred that the preservative provide antimicrobial activity, including antibacterial activity, anti-fungal activity or anti-yeast activity, or a combination thereof. Preferably, the preservative is selected from the group consisting of formaldehyde and formaldehyde donors, glutaldehyde, quaternium 15, urea, PHB esters, chloroxylenol, chloromethyl, triclosan, zinc pyrithione, oxafin A, chaton, trimethylammonium bromide, benzalkonium chloride, or a combination thereof.

In a further preferred embodiment, the lotion further comprises skin-protecting and / or skin-healing and / or skin-care active substances which give the skin an advantage which goes beyond a mere sensory and / or cosmetic advantage.

For example, in a preferred embodiment, active skin care may be provided in the form of stimulating skin regeneration, promoting skin physiology, strengthening the barrier function of the skin. The pH of the skin surface depends on the sweat secretion, bacterial flora and sebum composition. Depending on the skin region, the pH is between 4 and 7, with healthy skin in particular around 5.5.

Healthy human skin is characterized by the fact that it provides sufficient protection against microorganisms, germs and pathogens by means of their intact acid mantle that their buffering capacity and their alkali neutralizing capacity sufficient to harmful effects of surrounding fluids To ward off that there is a high degree of freedom from redness and that there is freedom from skin damage such as cuts, stings and burns, irritation, inflammation and allergies and that it is neither cracked nor dried out. In a preferred embodiment, at least one of the skin-healing and / or skin-protecting active substances contained in the lotion is antiseptic or contains at least one antiseptic substance, wherein the antiseptic substance is preferably an oil, in particular an essential oil.

This antiseptic oil is preferably an essential oil selected in particular from the group of Angelica fine - Angelica archangelica, Anis - Pimpinella anisum, Benzoin siam - Styrax tokinensis, Cabreuva - Myrocarpus fastigiatus, Cajeput - Melaleuca leucadendron, Cistrose - Cistrus ladaniferus, Copaiba balm - Copaifera reticulata, Costus root - Saussurea discolor, Edeltann needle - Abies alba, Elemi - Canarium luzonicum, Fennel - Foeniculum dulce Spruce needle - Picea abies, Geranium - Pelargonium graveolens, Ho leaves - Cinnamonum camphora, Immortelle (Strawflower) Helichrysum ang., Ginger extra - Zingiber off., St. John's wort - Hypericum perforatum, Jojoba, German chamomile - Matricaria recutita, Chamomile blue fine - Matricaria chamomilla, Chamomile rom. - Anthemis nobilis, Chamomile wild - Ormensis multicaulis, Carrot - Daucus carota, Mountain pine - Pinus mugho, Lavandine - Lavendula hybrida, Lit Sea Cubeba - (May Chang), Manuka - Leptospermum scoparium, Melissa - Melissa officinalis, Sea pine - Pinus pinaster, Myrrh - Commiphora molmol, Myrtle - Myrtus communis, Neem - Azadirachta, Niaouli - (MQV) Melaleuca quin. viridiflora, Palmarosa - Cymbopogom martini, Patchouli - Pogostemon patchouli, Peru balsam - Myroxylon balsamum var. pereirae, Raventsara aromatica, Rosewood - Aniba pink odora, sage - Salvia officinalis Horsetail - Equisetaceae, yarrow extra - Achilles millefolia, plantain lanceolate - Plantago lanceolata, Styrax - Liquidambar orientalis, Tagetes (Marigold) - Tagetes patula, Tea Tree - Melaleuca alternifolia, Tolu Balsam - Myroxylon Balsamum L., Virginia Cedar - Juniperus virginiana, Frankincense (Olibanum) - Boswellia carteri, Silver Fir - Abies alba.

In a preferred embodiment, the skin-protecting active ingredients contained in the lotion are a skin-protecting oil.

The skin-protecting substance is advantageously a skin-protecting oil, eg. B. also to a carrier oil, in particular selected from the group algae oil - Oleum Phaeophyceae, aloe vera oil - aloe vera brasiliana, apricot kernel oil - Prunus armeniaca, arnica oil - Arnica montana, avocado oil - Persea americana, borage oil - Borago officinalis, calendula oil - Calendula officinalis , Camellia oil - Camellia oleifera, Thistle oil - Carthamus tinctorius, Peanut oil - Arachis hypogaea, Hemp oil - Cannabis sativa, Hazelnut oil - Corylus avellana, St. John's wort oil - Hypericum perforatum, Jojoba oil - Simondsia chinensis, Carrot oil - Daucus carota, Coconut oil - Cocos nucifera, Pumpkin seed oil - Curcubita pepo , Kukui nut oil - Aleurites moluccana, Macadamia nut oil - Macadamia ternifolia, Almond oil - Prunus dulcis, Olive oil - Olea europaea, Peach kernel oil - Prunus persica, Rapeseed oil - Brassica oleifera, Castor oil - Ricinus communis, Black cumin oil - Nigella sativa, Sesame oil - Sesamium indicum, Sunflower oil - Helianthus a nnus, grapeseed oil - Vitis vinifera, walnut oil - Juglans regia, wheat germ oil - Triticum sativum, of which in particular borage oil, hemp oil and almond oil are advantageous.

According to another embodiment of the invention, it is advantageous to combine different oils in the lotion, i. H. So to combine the antiseptic oils with the skin-protecting oils or to combine the antiseptic oils and skin-protecting oils with each other.

In a preferred embodiment, the lotion additionally contains urea and / or lactic acid and / or citric acid and / or salts thereof.

Urea promotes skin health by providing anti-microbial, water-binding, anti-itching, anti-dandruff, skin smoothing, and inhibiting excessive cell growth. Furthermore, it can serve the skin as a moisturizing factor, i. H. it can help the skin to retain moisture.

Lactic acid and / or citric acid and / or their salts serve u. a. to support or renew the natural acid mantle or hydrolipid film of the skin. The hydrolipidic film of the skin is attacked or destroyed by alkaline influences, resulting in a loss of the barrier function of the skin, so that microorganisms or pollutants can more easily penetrate the skin. By the lactic and / or citric acid in the compositions according to the invention can be z. B. Remove residual alkali from clothing and adjust the pH of the textiles to a pH range around 5. The additional lactic acid acts; which is also part of the epidermis, additionally stabilizing the acidic pH of the skin (pH approx. 5.2) and serves as a moisturizing factor as it can improve the water-binding capacity of the skin.

In a further preferred embodiment, the lotion may contain further moisturizing factors, for example those selected from the following group: amino acids, chitosan or chitosan salts / derivatives, ethylene glycol, glucosamine, glycerol, diglycerol, triglycerol, uric acid, honey and hardened honey, creatinine, Cleavage products of collagen, lactitol, polyols and polyol derivatives (for example, butylene glycol, erythritol, propylene glycol, 1,2,6-hexane triol, polyethylene glycols such as PEG-4, PEG-6, PEG-7, PEG-8, PEG-9, PEG-10 , PEG-12, PEG-14, PEG-16, PEG-18, PEG-20), pyrrolidonecarboxylic acid, sugar and sugar derivatives (for example, fructose, glucose, maltose, maltitol, mannitol, inositol, sorbitol, sorbitylsilanediol, sucrose, trehalose, xylose , Xylitol, glucuronic acid and its salts), ethoxylated sorbitol (sorbeth-6, sorbeth-20, sorbeth-30, sorbeth-40), hardened starch hydrolysates and mixtures of hardened wheat protein and PEG-20 acetate copolymer, in particular panthenol.

Preferably, the fibrous sheet of the present invention is used as a sanitary article, particularly as a wet wipe or wet toilet paper.

A wet wipe can be used, for example, for personal care, such as a tissue or as a disinfectant wipe, or in the household as a wipe.

The invention will be illustrated by examples without, however, being limited thereto.

Inventive Example 1: Airlaid Nonwoven with pH-Dependent Disintegration Capacity To produce an airlaid pulp web having a total basis weight of about 50 g / m ² , a pulp material stream having a weight per unit area of about 45.5 g / m ^{2 was applied} via the laying head system deposited by vacuum on the laying sieve passing underneath.

After slight compression of the fiber composite by means of heated smooth rollers and subsequent embossing calender was in each case one side each with an approximately 30% aqueous dispersion of a binder A (EUDRAGIT ^® FS 30 D, Evonik Industries AG, Essen, Germany) based on carboxyalkyl methacrylate and an approximate 8% aqueous dispersion of a binder B (VINNAPAS ^® EN 1020 , Wacker Chemie AG, Burghausen, Germany) sprayed on ethylene / vinyl acetate-based, wherein the specified percentages refer to the binder content of the respective dispersion.

The binder B and the binder A were applied in a mixing ratio of 1: 2. The total binder coverage was adjusted to about 9% by weight of the total basis weight, based on the total basis weight of the resulting airlaid pulp web when dried.

After drying and condensation of the binder, the produced fleece was rolled up.

Composition of the obtained airlaid nonwoven web component Example 1: Pulp fiber 45.5 g / m ² Binder A 3.0 g / m ² Binder B 1.5 g / m ²

Subsequently, the wet strengths of the obtained nonwoven web were measured in the wet state. For this purpose, 10 × 10 cm large sections of the resulting web at room temperature for 60 min. in vessels containing 100 ml of 0.1 M acetic acid acetate buffer of the indicated pH ("buffer") or in vessels containing 100 ml of 0.1 M acetic acid acetate buffer containing in addition 2.0 g of NaCl per 100 ml of buffer ("buffer + NaCl"), and then the wet strength in the tensile test DIN 54540-8 measured.

Analogously, 10 × 10 cm sections at room temperature in vessels containing 100 ml each of a 0.1 M phosphate buffer of the indicated pH values ("buffer") or 0.1 M phosphate buffer of the indicated pH values, in addition 2.0 g NaCl per 100 ml of buffer ("buffer + NaCl") contained, and after 60 minutes exposure to the wet tensile strength after DIN 54540-8 measured.

The respective wet strength values in N / 50 mm are shown in Table 1, with the pH values 4.0, 5.5 and 7.0 in each case giving an average of 8 independent measurements. For the pH 8.0, two mean values from 8 independent measurements are given.

The pulp web prepared in Example 1 had sufficient wet strength at pH 4.0 and pH 5.5 which was not affected by addition of 2.0 g NaCl per 100 ml buffer.

At a pH of 7.0, a significant reduction in wet strength of about 50% based on wet strength measured at pH 4.0 and 5.5 has already been demonstrated. The respectively measured wet solids values as well as the decrease of the wet strength with increase of the pH value are not influenced by an addition of 2.0 g NaCl per 100 ml of the used buffer. Wet solids in N / 50 mm buffer Buffer + NaCl 0.1 M acetic acid-acetate buffer pH = 4.0 6.4 7.1 6.4 6.8 6.6 6.3 6.7 6.2 6.9 6.4 6.9 6.4 6.8 6.2 7.0 6.0 Average 6.59 6.55 0.1 M acetic acid-acetate buffer pH = 5.5 6.3 7.0 6.1 6.4 6.5 6.4 6.7 6.3 6.8 6.0 6.9 6.4 6.7 6.9 7.2 6.2 Average 6.58 6.53 0.1 M phosphate buffer pH = 7.0 3.1 3.5 3.5 3.5 2.9 2.8 2.8 2.7 3.2 3.7 3.6 2.9 3.3 2.9 3.2 3.3 Average 3.18 3.19 0.1 M phosphate buffer pH = 8.0 2.2 2 2.1 2.7 2.6 2.3 2.5 2.5 2.4 1.9 2.5 2.5 2.5 2.0 2.2 1.9 2.1 2.3 2.2 2.1 2.1 2.1 2.1 1.8 2.3 2.5 2.2 2.6 2.0 2.4 2.1 2.0 Average 2.28 2.19 2.24 2.26 Table 1: Wet strength of 10 × 10 cm sections of a nonwoven fabric according to the invention after 60 minutes exposure time in buffer solutions with different pH.

Inventive example 2: moist airlaid nonwoven with pH-dependent decomposability

10 × 10 cm sections of the airlaid web prepared in Example 1 according to the invention with pH-dependent decomposability were wetted in each case with 3 ml of the commercially available aqueous lotions A to C indicated in Table 2. After 30 minutes of exposure at room temperature, the wet strength was measured. Lotion A Lotion B Lotion C preservatives preservatives preservatives phenoxyethanol Polyaminopropyl biguanide (PAPB) Polyaminopropyl biguanide (PAPB) potassium sorbate phenoxyethanol phenoxyethanol benzoic acid Dehydroacetic acid, DHA surfactants surfactants surfactants Polyglceryl-4 caprate dipropylene dipropylene Caprylyl / capryl glucoside Caprylyl / capryl glucoside Polyglyceryl-4 caprate Polyglyceryl-4 caprate Ethylhexylglycerin Ethylhexylglycerin pH: 5.5 pH: 5.5 pH: 5.5 Table 2: Uses commercial aqueous lotions for wet wipes.

The measurement of the wet strength of the webs wetted with the respective lotion took place after 1 h of storage of the 10 × 10 cm sections at 23 ° C. and 50% relative humidity. Subsequently, the wet strength in the tensile test was after DIN 54540-8 determined as the mean value from 8 independent measurements ("lotion pH value: 5.5").

The measurement of the wet strength at pH 7.0 and 8.0 was carried out analogously to Example 1 according to the invention wherein the 10 × 10 cm sections at room temperature in vessels containing 100 ml 0.1 M phosphate buffer of the indicated pH values ("buffer"). ) were given. After an exposure time of 60 minutes, the measurement of the wet strength in the tensile test was carried out DIN 54540-8 ,

The respective wet solids values in N / 50 mm are shown in Table 3, with an average of 8 independent measurements being given for the pH values 5.5 and 7.0. For the pH 8.0, two mean values from 8 independent measurements are given.

After wetting with commercially available lotions having a pH of 5.5, the pulp web produced in Example 1 had sufficient wet strength, it being possible to detect a significant reduction of the wet strengths even at a pH of 7.0. At a pH of 8.0, the wet strengths decreased by about 50%, based on the wet strength measured at a pH of 5.5. Lotion A Lotion B Lotion C Wet solids in N / 50 mm - Lotion pH: 5.5 5.2 5.1 5.3 5.6 5.1 4.9 4.7 5.4 5.2 5.7 4.9 5.5 4.7 5.0 5.5 5.8 4.9 5.3 4.8 5.2 5.7 5.0 5.3 5.4 Average 5.01 5.48 5.48 0.1 M phosphate buffer pH = 7.0 4.7 4.4 4.6 4.2 4.5 3.8 4.1 4.6 4.5 4.3 4.6 4.4 4.7 4.0 4.7 4.5 4.8 4.3 5.0 4.2 4.8 4.7 4.3 4.3 Average 4.46 4.54 4.38 0.1 M phosphate buffer pH = 8.0 2.4 3.1 2.5 2.7 2.7 2.5 2.6 3.0 2.8 2.5 3.5 2.5 2.6 3.0 2.9 2.5 2.7 2.3 2.4 3.2 2.2 1.9 2.7 2.7 2.6 3.1 2.2 2.1 3.5 2.4 2.6 2.9 2.4 1.8 2.9 2.6 2.1 3.0 2.5 2.6 2.8 2.4 2.8 3.1 2.5 2.0 3.3 2.4 Average 2.51 3.05 2.50 2.26 3.01 2.48 Table 3: Wet solids of 10 × 10 cm wetted sections of a nonwoven fabric according to the invention.

Comparative Example 3: Airlaid nonwoven with binder B

To produce an airlaid pulp web having a total basis weight of about 50 g / m ² , a pulp flow of material having a weight per unit area of about 45 g / m ^{2 was} deposited via the laying head system by vacuum on the laying screen guided underneath.

After slight compression of the fiber composite by means of heated smooth rollers and subsequent embossing calender both sides were each sprayed with an approximately 11% aqueous dispersion of a binder B (VINNAPAS ^® EN 1020, Wacker Chemie AG, Burghausen, Germany) based on ethylene / vinyl acetate, wherein the stated percentage refers to the binder content of the dispersion.

The binder content was adjusted to about 10 wt .-% of the total basis weight, based on the total basis weight of the resulting airlaid pulp web in the dried state.

After drying and condensation of the binder, the produced fleece was rolled up. Composition of the air-laid nonwoven webs component Comparative Example 3 Pulp fiber 45 g / m ² Binder A - Binder B 5 g / m ²

Subsequently, the wet strengths of the obtained nonwoven web in the wet state were measured without addition of a lotion as in Example 1.

In parallel, 10 × 10 cm sections were each wetted with 3 ml of the commercial aqueous lotions A to C shown in Table 2. After a reaction time of 30 minutes at room temperature, the wet strength was measured as indicated in Example 2.

The measurement of the wet strength at a pH of 5.5 was carried out in the airaid wetted with the respective lotion Airlaid web after 1 h storage of 10 × 10 cm sections at 23 ° C and 50% relative humidity. 10 × 10 cm sections of the unwetted airlaid web were placed in vessels containing 100 ml of a 0.1 M acetic acid acetate buffer at pH 5.5. The measurement of the wet strength was carried out after a contact time of 60 minutes in the tensile test DIN 54540-8 as average of 12 independent measurements.

After an exposure time of 60 minutes in vessels containing 100 ml of a 0.1 M phosphate buffer with a pH of 7.0, the measurement of the wet strength was carried out in the tensile test in each case DIN 54540-8 on 10 × 10 cm wetted and unwetted cutouts of the fleece.

The respective wet strengths in N / 50 mm are shown in Table 4.

The nonwoven fabric made only with a binder B exhibits a higher wet strength both when wetted and after being wetted with a lotion having a pH of 5.5, than the nonwoven produced in Examples 1 and 2 according to the invention.

However, wet strength does not decrease after incorporation into a pH 7.0 0.1 M phosphate buffer.

In the wetted sections of the nonwoven wet strength even increases, since after washing the surfactants contained in the lotions used, the cellulose fibers adhere more strongly to each other.

Since the binder A does not dissolve or detach from the fibers, the wet strength does not decrease even after prolonged storage at a pH of 7.0. Without lotion Lotion A Lotion B Lotion C Wet solids in N / 50 mm - pH value: 5.5 8.36 9.5 8.9 10.86 11.26 8.8 10.32 10.21 10.74 10.12 10.56 10.01 10.21 8.89 11.01 9.71 11.01 9.68 9.64 9.54 12.76 10.56 10.71 8.99 11.59 9.38 10.12 9.31 9.24 10.12 9.76 9.78 8.21 9.12 9.97 10.31 11.18 9.24 10.14 10.63 10.52 9.92 10.02 9.72 8.62 9.15 11.12 9.98 Average 9.85 9.91 10.01 10.20 0.1 M phosphate buffer pH = 7.0 10.21 10.5 10.4 11.04 9.68 10.82 9.98 10.32 9.79 9.12 11.32 10.05 11.62 11.44 11.33 9.7 11.43 9.54 10.82 10.91 13.99 9.59 10.89 10.98 10.34 8.99 11.43 10.62 12.06 12.06 9.66 10.18 9.86 9.12 10.32 9.89 11.53 11.62 10.51 11.92 9.71 9.21 11.14 9.56 13.02 13.99 11.34 11.04 Average 9.82 10.63 11.44 10.65 Table 4: Wet strength of 10 × 10 cm wetted and unwetted cutouts of a nonwoven fabric made only with binder B.

Comparative Example 4: Airlaid nonwoven with binder A

To produce an airlaid pulp web having a total basis weight of about 50 g / m ² , a pulp flow of material having a weight per unit area of about 45 g / m ^{2 was} deposited via the laying head system by vacuum on the laying screen guided underneath.

After slight compression of the fiber composite by means of heated smooth rolls and subsequent embossing calender both sides were each with a 30% aqueous dispersion of a binder A (EUDRAGIT ^® FS 30 D, Evonik Industries AG, Essen, Germany) are sprayed on ethylene / vinyl acetate-based, wherein the stated percentage refers to the binder content of the dispersion.

The binder content was adjusted to about 10 wt .-% of the total basis weight, based on the total basis weight of the resulting airlaid pulp web in the dried state.

After drying and condensation of the binder, the produced fleece was rolled up. Composition of the air-laid nonwoven webs component Comparative Example 4 Pulp fiber 45 g / m ² Binder A 5 g / m ² Binder B -

Subsequently, the wet strengths of the obtained nonwoven web in the wet state were measured without addition of a lotion as in Example 1.

In parallel, 10 × 10 cm sections were each wetted with 3 ml of the commercial aqueous lotions A to C shown in Table 2. After a reaction time of 30 minutes at room temperature, the wet strength was measured as indicated in Example 2.

The respective wet strengths in N / 50 mm are shown in Table 5.

The nonwoven produced only with a binder A has both compared to the nonwoven produced in Example 1 and 2 according to the invention both unwetted and wetted at a pH of 5.5 significantly reduced wet strength, so that the integrity of the wet tissue already by a low mechanical load is destroyed.

The wet strength continues to decrease after incorporation in a 0.1M phosphate buffer of pH 7.0 and 8.0, respectively. Without lotion Lotion A Lotion B Lotion C Wet solids in N / 50 mm - pH value: 5.5 2.3 2.2 1.8 2.4 2.6 2.1 1.9 2.3 2.5 2.3 2.2 1.9 1.9 2.1 2.2 1.8 1.9 2 2.3 2 2.2 2.3 2.5 1.9 2.5 2.1 2.2 2.4 2.3 2.6 2.1 2.2 Average 2.23 2.15 2.26 2.11 0.1 M phosphate buffer pH = 7.0 1.5 1.3 1.3 1.2 1.5 1.3 1.3 1.3 1.6 1.2 1.5 1.6 1.5 1.5 1.3 1.3 1.3 1.5 1.3 1.5 1.6 1.2 1.2 1.5 1.2 1.8 1.1 1.2 1.1 1.3 1.5 1.5 Average 1.43 1.34 1.38 1.36 0.1 M phosphate buffer pH = 8.0 1.2 1.4 1.2 1.1 1.2 1.5 1.4 1.2 1.1 1.1 1.1 0.9 1.1 1.1 0.9 1.4 1.2 1.3 1.2 1.1 1.3 1.2 1.4 1.2 1.1 1.1 1 1.4 1.5 1.3 1.2 1.1 1 1 1 1.5 1.1 1.2 1.3 0.9 1.1 1.2 0.8 1.2 1.2 1.1 1.5 0.9 Average 1.09 1.18 1.11 1.20 1.20 1.26 1.25 1.14 Table 5: Wet strength of 10 × 10 cm wetted and unwetted cutouts of a nonwoven made only with binder A.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5629081 [0004]
• US 5,384,189 [0005]
• US 4755421 [0006]
• US 5667635 [0007]
• DE 2817604 C2 [0008]
• US 6103865 [0079]

Cited non-patent literature

• DIN 54540-8 [0139]
• DIN 54540-8 [0140]
• EN 1020 [0160]
• DIN 54540-8 [0164]
• DIN 54540-8 [0165]
• DIN 54540-8 [0170]
• DIN 54540-8 [0171]
• DIN 54540-8 [0180]
• DIN 54540-8 [0181]

Claims (17)

Fiber-containing fabric, characterized in that the fibrous sheet has a pH-dependent decomposability, wherein the sheet contains at least two binders, wherein at least 1 binder A is a pH-dependent stability and at least 1 binder B is a pH-independent Stability, wherein the binder A is stable at a pH of less than or equal to 6.4 and is not stable at a pH in the range of 6.9 or higher. Fiber-containing fabric according to claim 1, characterized in that the proportion of at least 1 binder A and at least 1 binder B in a range of 1 wt .-% to 35 wt .-%, each based on the total weight of the fibrous sheet is. Fiber-containing fabric according to one of claims 1 or 2, characterized in that the fibrous sheet at least 1 binder A in a proportion of 50 wt .-% to 90 wt .-%, preferably from 58 wt .-% to 88 wt .-% , and at least 1 binder B in a proportion of 10 wt .-% to 50 wt .-%, preferably from 12 wt .-% to 42 wt .-%, each based on the total content of the binder comprises. A fiber-containing fabric according to any one of claims 1 to 3, characterized in that the at least one binder A is a homopolymer or copolymer which carboxylic acid and / or sulfonic acid and / or sulfonamide groups, more preferably carboxylic acid groups. A fiber-containing fabric according to any one of claims 1 to 4, characterized in that the binder A from the group consisting of acrylate homopolymers, methacrylate homopolymers, methyl methacrylate homopolymers, carboxylalkyl methacrylate copolymers, acrylate-methacrylate copolymers, polyvinyl acetate phthalates and mixtures thereof is selected. Fiber-containing fabric according to claim 4 or 5, characterized in that the binder A is a carboxyalkyl methacrylate copolymer. Fiber-containing fabric according to one of the preceding claims, characterized in that the at least one binder B is selected from the group consisting of polyalkanes, polyamides, polyimines, polyesters, polyethers and polyureas and mixtures thereof. A fiber-containing fabric according to any one of the preceding claims, characterized in that the binder B is selected from the group consisting of polyethylene, polypropylene, polyesters, styrene-butadiene copolymers, styrene-acrylate copolymers, ethylene-vinyl acetate copolymers, and mixtures thereof, is selected. Fiber-containing fabric according to one of the preceding claims, characterized in that the fiber-containing fabric is moist. Fiber-containing fabric according to one of the preceding claims, characterized in that the fibrous sheet comprises a liquid, preferably lotion, having a pH of less than or equal to 6.4. Fiber-containing fabric according to one of the preceding claims, characterized in that the fiber-containing fabric is a nonwoven. Fiber-containing fabric according to one of the preceding claims, characterized in that the fiber-containing fabric is provided with at least one coating having a pH-dependent solubility. Fiber-containing fabric according to one of the preceding claims, characterized in that fibrous fabric is single-layered. Fiber-containing fabric according to one of the preceding claims, characterized in that the fiber-containing fabric has a plurality of layers, none of these multiple layers being impermeable to aqueous media. A method of making a fibrous sheet according to any one of the preceding claims, comprising the steps of: (a) providing fibers, (b) depositing the fibers on a receiving surface to obtain a fibrous bed, (c) densifying the fibrous bed to obtain a consolidated one Faserbettes, characterized in that in steps (a) and / or (b) and / or (c) and / or between steps (a), (b) or (c) and / or after step (c) at least 1 binder A, which has a pH-dependent stability, and at least 1 binder B, which has a pH-independent stability, is added, wherein the at least one binder A at a pH of less than or equal to 6, 4 is stable and not stable at a pH in the range of 6.9 or higher. A method according to claim 13, characterized in that in or after step (c) at least 1 binder A, which has a pH-dependent stability, and at least 1 binder B, which has a pH independent stability, is added. Use of a fibrous sheet according to any one of claims 1 to 14 as a hygiene article, in particular as a wet wipe or moist toilet paper.