DE69728563T2 - NON-CELLULOSE FIBERGLAVES WITH AN IMPROVED WET STRENGTH - Google Patents

Description

Field of the invention

The The present invention relates to a nonwoven fabric chemically bonded Non-cellulose fibers with improved tensile properties in water. More precisely The present invention relates to a nonwoven fabric of non-cellulose fibers, comprising a substantially formaldehyde-free latex binder and to provide improved tensile properties able in the water is. A process for producing such substances is another Aspect of the invention.

background the invention

One Nonwoven fabric is a fabric or a continuous web made of mechanically deposited Fibers. The fibers can fortuitously arranged or oriented in one direction. The farthest Commonly used fibers include cellulose fibers, polyamides, polyesters, Polypropylene and polyethylene. The spun fibers that pulled can be are made by carding, aerodynamic deposition or wet-laid process directly on a porous Band filed, often using electrostatic charge. The layer is then with bonded to a binder and in an oven or calender treated to complete the binding process.

A Series of procedures has been developed to randomize a binder Apply fibers. Typically, an emulsion binder system water-based, wherein a thermoplastic or thermosetting synthetic polymer latex manufactured and a loose to be treated Fibrous tissue in view of the structural weakness of Fabric is dipped in, soaked with or using special equipment sprayed with it becomes; the fabric thus treated is dried and cured to to achieve adequate bonding. Alternatively, an aqueous or based on a solvent solution Binder system of a thermoplastic or thermosetting Resin can be used to impregnate the fiber network.

Other Methods include the application of thermoplastic or thermoset Resin powders on the fibers before or after production of a fabric from it and the performing of the fabric by hot rolling or a hot press to join the fibers. Alternatively, you can thermoplastic fibers having a softening point below that of Base fibers are dispersed in a fabric of the latter, wherein sufficient heat and pressure is applied, for example by the use of hot rollers to apply the thermoplastic fibers soften and bind the fiber network.

Generally spread latices for Nonwovens are those made from polymers of butadiene-styrene, Butadiene-acrylonitrile, vinyl acetate, acrylic monomers, e.g. methyl acrylate, Ethyl acrylate, methyl methacrylate, and the like. these can Contain acrylonitrile. See, for example, GB-A-1,112,888, EP-A-470,689 and US-A-4,752,523. While the emulsion binder system is the most widely used method for the production of nonwovens, bring the previously used Homopolymers, copolymers and terpolymers have one or more disadvantages with himself. To be suitable as a textile material, the synthetic must Polymer have different physical properties. The desired Properties include adequate tensile strength over one relatively large Temperature range, high modulus or high rigidity below certain conditions and good textile qualities, e.g. Firmness, grip and case.

It It is understood that the use of self-crosslinking or with Melamine-formaldehyde resin "glued" latex widely used is to give a non-cellulosic nonwoven product improved tensile properties to lend in water. However, these systems contain formaldehyde and give this during the Drying / curing cycle from. Furthermore essentially require all commercially available self-crosslinking and melamine discontinued latices for proper cross-linking a temperature of at least 138 ° C (280 ° F) and preferably 149 ° C (300 ° F).

The US-A-5,326,853 reduces formaldehyde formation by use a ketoxime or amide blocked isopropenyl-α, α-dimethylbenzyl isocyanate instead of the conventional one N-methylol funktinellen monomers to the aromatic diene / vinyl mixture to network. Optional additional Monomers include acrylonitrile. Use with both paper as well as with non-cellulose nonwovens is proposed. The emulsion polymerization is using conventional Emulsion surfactants performed. The latex examples were tested on paper, drying at 158 ° C (315 ° F) has been.

There the melting point of many non-cellulose fibers below that suitable Crosslinking required temperature is lying, polypropylene melts for example at about 121 ° C (250 ° F), can conventional latices Not used. Accordingly were Polypropylene fibers have never been very successful in the nonwovens industry. The Problem existed in the specific development of a suitable Latex binder to provide acceptable tensile properties.

One The aim of the present invention is to provide a Nonwoven fabric made of chemically bonded non-cellulose fibers. One Another object of the present invention is to provide a Nonwoven fabric, which is a random Arrangement of non-cellulose fibers and a substantially formaldehyde-free Latex binder comprises, at temperatures below the meltbonding temperature non-cellulose fibers to develop maximum tensile properties is capable. Another object of the present invention is to provide a nonwoven fabric that is a random Arrangement of non-cellulose fibers and a substantially formaldehyde-free Latex binder includes that to provide improved Tensile properties in water is capable. Another goal The present invention is to provide a nonwoven fabric made of chemically bonded non-cellulose fibers, which is simple and economical can be produced.

Summary the invention

Short is said according to this Invention provided a nonwoven fabric, which is a random arrangement non-cellulose fibers and a substantially formaldehyde-free Latex binder as set forth in claim 1. One Another aspect of the invention is a method for the production such a substance according to claim 15. The latex binder comprises a latex polymer prepared by emulsion polymerization of a monomer mixture in the presence of a polymeric surfactant becomes. The monomeric mixture consists of a conjugated diene monomer, a vinyl-substituted aromatic monomer and a vinyl cyanide monomer. The conjugated diene monomer can be selected from piperylene, isoprene, 2,3-dimethyl-1,3-butadiene and 1,3-butadiene selected be. The vinyl-substituted aromatic monomer may be selected from α-methylstyrene, p-tert-butylstyrene, m-vinyltoluene, p-vinyltoluene, 3-ethylstyrene and styrene. The vinyl cyanide monomer may be acrylonitrile, methacrylonitrile, ethacrylonitrile and phenylacrylonitrile be.

The polymeric surfactant makes up about 15 to 35% by weight, based on dry Latex out. The preferred polymeric surfactant preferably contains about 25 to 27% by weight of a styrene / acrylic acid / α-methylstyrene copolymer in water, which neutralizes with about 6 to 7 wt .-% ammonium hydroxide has been.

The contains substantially formaldehyde-free latex binder at least about 6.7 weight percent vinyl cyanide monomer to the non-cellulose fibers to bind and produce a nonwoven fabric that is at least about 78 % of the wet tensile strength in the transverse direction can be maintained. The nonwoven fabric From chemically bound non-cellulose fibers has in comparison to a comparable nonwoven fabric of the same type, essentially the same monomeric formulation with substantially formaldehyde-free Latex binder, but is free of vinyl cyanide monomer, an at least 10% improvement in wet tensile strength.

Suitable non-cellulosic fibers include glass fibers or high polymer fibers. The high polymers include polyolefins, polyesters, acrylates, polyamides and the like. The polyolefin fibers include polypropylene, polyethylene, polybutene and copolymers thereof. The polyester fibers comprise a long-chain synthetic polymer consisting of at least 85% by weight of an ester of a dihydric alcohol and a terephthalic acid such as polyethylene terephthalate, and additionally liquid crystal polyesters, thermotropic polyesters and the like. The acrylic fibers include all fiber-forming substances comprising a long-chain synthetic polymer consisting of at least 85% by weight of acrylonitrile units -CH ₂ CH (CN) -. Of course, other types of non-cellulosic fibers may also be used in accordance with the teachings of the present invention. For example, high modulus fibers, more commonly known as graphite fibers, can also be used from rayon, polyacrylonitrile or petrol pitch.

Of the Nonwoven fabric made from non-cellulosic fibers is provided by the supply a random one Arrangement of non-cellulose fibers formed. Next is a substantially formaldehyde-free latex binder on the Applied fibers. Then the latex binder is heated to chemically bond the non-cellulose fibers and a dimensionally stable To form nonwoven fabric.

detailed Description of the Preferred Embodiments

The present invention relates to a nonwoven fabric of chemically bonded non-cellulosic fibers. The fabric can be used for soft and drapable fabrics such as diapers, sanitary napkins, medical clothing, masks, caps and curtains, as well as rigid and elastic fabrics such as garment inserts, upholstery fabrics, quilts, waterbed cushioning, and insulation and upholstery of clothing ,

Of the Fabric according to the present The invention is accomplished by making a web of randomly-arranged non-cellulosic fibers formed using a substantially formaldehyde-free latex binder chemically bound. The essentially formaldehyde-free latex binder can bind the non-cellulose fibers chemically and a dimensionally stable Form nonwoven fabric. As is well known in the art For example, the latex binder may be periodically spaced Binding pattern on the layer of randomly arranged non-cellulose fibers applied or uniform applied to the entire layer of non-cellulosic fibers.

Of the Term "essentially formaldehyde-free "refers on a latex binder, which - after in the field of Invention Well Known Nash / HPLC Method (High Performance Liquid Chromatography) determined - during the usual Drying / curing cycle of the latex binder does not exceed 0.7 (ppm) parts of formaldehyde per million parts of latex binder, and the term "chemically bound" refers herein to a bond that is not formed as a result of a heat treatment, as is the case, for example, during fusion bonding, what through a physical change is occupied in the fibers.

The non-cellulosic fibers of the fabric may be glass fibers or high polymer fibers. The glass fibers are of a type well known in the art and made of molten glass which is extruded through small openings and then spun at high speed. Suitable high polymers include polyolefins, polyesters and acrylates, polyamides and the like. The polyolefin fibers include polypropylene, polyethylene, polybutene and copolymers thereof. The polyester fibers include any of the long chain synthetic polymers consisting of at least 85% by weight of an ester of a dihydric alcohol and a terephthalic acid such as polyethylene terephthalate, and additionally liquid crystal polyesters, thermotropic polyesters, and the like. The acrylic fibers include all fiber-forming substances comprising a long-chain synthetic polymer consisting of at least 85% by weight of acrylonitrile units -CH ₂ CH (CN) -. Of course, other types of non-cellulosic fibers may also be used in accordance with the teachings of the present invention. For example, high modulus fibers, more commonly known as graphite fibers, can also be used from rayon, polyacrylonitrile or petrol pitch.

The Non-cellulose fibers can have any suitable size and be randomly arranged in any suitable thickness, as appropriate desired End use of the nonwoven fabric. The non-cellulose fibers have typically one length from about 6.3 to 51 mm (0.25 to 2 inches) and typically about 1.3 to 6.7 tex (1.2 to 6 denier). The non-cellulose fibers can in an overlapping, crossed over random Arrangement to a thickness of about 6.3 mm (0.25 inches) or less superimposed to form a web of non-cellulosic fibers. The non-cellulose fibers can be arranged in any manner, such as by a wet-laid process, aerodynamic laying or carding.

After this the carding as desired fortuitously A latex binder is applied to the fibers applied. The latex binder is in an effective amount used, which leads to that the resulting fabric has sufficient strength and cohesiveness for the intended end use. Of course, the exact amount of used depends Latex binder partly due to factors such as the Fiber type, the weight of the fiber layer, the composition of the fiber Latex binder and the like, from. For end use, the more For example, more binders may be used become. A typical amount of latex binder on a web made of non-cellulose fibers is, is about 15 to 40 wt .-%. Preferably, the minimum amount of latex binder is applied, to the minimum required physical properties of the Nonwoven fabric, such as tensile strength, grip and the like, as is well known in the art is.

The latex binder used in accordance with the present invention may be prepared by well-known conventional emulsion polymerization methods using one or more ethylenically unsaturated monomers and a polymeric surfactant as disclosed herein, and additionally conventional additives such as free-radical initiators, optionally chain transfer agents, chelating agents and the like, as described in U.S. Patent No. 5,166,259 to Schmeing and White is set forth.

suitable ethylenically unsaturated Monomers for the emulsion polymerization reaction include conjugated diene monomers, vinyl-substituted aromatic monomers and vinyl cyanide monomers.

The conjugated diene monomers generally contain 4 to 10 carbon atoms, preferably 4 to 6 carbon atoms. Examples of specific Diene monomers include piperylene, isoprene, 2,3-dimethyl-1,3-butadiene and the like, and preferably 1,3-butadiene. The amount of used conjugated diene monomers about 50 to 70 wt .-%, preferably about 55 to 65 wt .-%, in particular about 60% by weight. Containing the vinyl-substituted aromatic monomers generally 8 to 12 total carbon atoms. Examples of specific vinyl-substituted aromatic monomers include α-methylstyrene, p-tert-butylstyrene, m-vinyltoluene, p-vinyltoluene, 3-ethylstyrene and the like, and preferably styrene. The amount the vinyl-substituted aromatic monomers used is about 16 to 50 wt .-%, preferably about 27 to 50 wt .-%, in particular about 27% by weight. Naturally when the amount of vinyl-substituted aromatic monomers in the present invention is more than about 50% by weight, the Latex brittle, whereby it is no longer acceptable as a binder and non-cellulosic nonwovens imparts unacceptable dry and wet tensile properties. Furthermore the more conjugated diene monomers and the less vinyl substituted aromatic monomers are added, generally softer handle and lower tensile properties in non-cellulosic nonwovens receive. Similarly, the fewer conjugated diene monomers and the more vinyl substituted aromatic monomers are added, generally more rigid Handle and higher Tensile properties in non-cellulosic nonwovens obtained, to such an extent that the latex binder does not form a continuous film and the tensile properties decrease, which makes the non-cellulose nonwoven fabrics too stiff.

The Vinyl cyanide monomers can Methacrylonitrile, ethacrylonitrile, phenylacrylonitrile and the like and preferably acrylonitrile. The amount of vinyl cyanide monomers used is at least about 6.7% by weight, preferably about 6.7 to 15% by weight, in particular about 6.7 to 10 wt .-%.

The polymeric surfactant is preferably a solution-neutralized acrylic resin. In a preferred embodiment For example, the polymeric surfactant is a resin containing about 25 to 27% by weight of a Styrene / acrylic acid / α-methyl styrene copolymer contains in water, with a base such as ammonium hydroxide, potassium hydroxide, Calcium hydroxide and the like, was neutralized and an acid value from about 100 to 300 and a weight average molecular weight of more than 7,000. In particular, the polymeric surfactant is with neutralizes about 6 to 7 wt .-% ammonium hydroxide and has a acid value of about 205, a weight average molecular weight of about 8,500 and an average monomer weight ratio between α-methylstyrene, Styrene and acrylic acid in parts by weight of about 37:32:31.

The Resin is made according to the im U.S. Patent No. 4,529,787 to Schmidt et al. produced method described wherein a small amount of diethylene glycol monoethyl ether as a solvent is used. additional Resins useful in the present invention may be prepared according to the teachings U.S. Patent No. 4,414,370 to Hamielec et al. and the US patent No. 4,546,160 to Brandt et al. getting produced.

The Amount of the polymer surfactant added to the reactor is about 15 to 35 wt .-%, preferably about 26 wt .-%, on a dry Latex base, it being believed that about 30% by weight in particular are to be preferred.

The radical initiators that are used to polymerize the various above latex binder forming monomers include sodium persulfate, Ammonium persulfate, potassium persulfate and the like. Others too radical initiators can to be used during temperature used to decay or become active, such as different peroxides, e.g. cumene hydroperoxide, Dibenzoyl peroxide, diacetyl peroxide.

The optional chain transfer agent may generally be any suitable chain transfer agent known in the art. Optional chain transfer agents include mercaptans such as alkyl and / or aryl mercaptans having from 8 to about 18 carbon atoms, and preferably from about 12 to about 14 carbon atoms. The tertiary alkyl mercaptans having 12 to 14 carbon atoms are particularly preferable. Examples of suitable mercaptans include n-octylmercaptan, n-dodecylmercaptan, t-octylmercaptan, t-dodecylmercaptan, tridecylmercaptan, tetradecylmercaptan, hexadecylmercaptan and the like, and mixtures thereof. The amount of chain transfer agent is generally about 0.2 to about 2.5 parts per 100 parts monomer, preferably from 0.4 to about 0.9 parts per 100 parts monomer, more preferably about 0.7 parts per 100 parts monomer. In a preferred embodiment, the chain transfer agent is a dodecylmercaptan chain transfer agent such as Sulfole 120 sold by Phillips 66 Co.

chelating agent can also during The polymerization can be used to various metal contaminants to bind and to form a uniform To achieve polymerization. The amount of such chelating agents is generally low and amounts from about 0.02 to about 0.08, preferably about 0.05 parts of chelating agent per 100 parts total monomer. Examples of suitable chelating agents include ethylenediaminetetraacetic acid, nitrilotriacetic acid, citric acid and ammonium, potassium and ammonium Sodium salts thereof. Preferred chelating agents include those chelating agents, available under the name Hamp-ene from Hampshire Chemical.

In a preferred embodiment finds the polymerization of the ethylenically unsaturated monomers and the polymeric Surfactants take place sequentially. The following examples are for illustration the sequential addition of the ethylenically unsaturated Monomers and the polymeric surfactant to produce the latex binder.

Examples 1 and 2

Two separate latices were prepared according to the present invention. Each latex was made by adding a charge of deionized water, polymeric surfactant and hemi-ene to a reactor having a volume of about 76 dm ³ (20 gallons) and a capacity of about 63.5 kg (140 pounds) latex. After the polymeric surfactant had been added, the reactor was evacuated (about 508 mm (20 inches) of mercury), purged with nitrogen, and heated to a desired temperature. Ammonium persulfate was then added to the reactor as a 10% solution in deionized water.

A Batch comprising styrene, butadiene, acrylonitrile and dodecylmercaptan, was then added to the reactor sequentially in equal feeds. In Table 1, the weight percentages of styrene, butadiene, Acrylonitrile and dodecyl mercaptan listed for example 1 and 2 labeled latices were added to the reactor.

Table 1

The first loading for each latex was added about 5 minutes after adding the ammonium persulfate Reactor added. additional Feeds were then graded at intervals of about 15 or 20 min added to the reactor. The feeds can vary depending on the amount of polymerizable Latex binder over any number of graduated intervals may be added. For example, the Feeds in 6 to 12 stages or more in equal incremental samples be added. After adding the last batch to the reactor was the reaction was monitored, until the solids content of latex in the reactor is an acceptable degree of conversion pointed. In cases, in which the reaction rate during the residence time undesirably slow was an extra Amount of ammonium persulfate added.

After the desired degree of conversion was achieved, the individual latices were placed in a 227 dm ³ (60 gallon) vessel and steam and vacuum stripped. This process involved the addition of a defoamer, such as Drew L198. Also, the preservative Kathon LX ^® was added together with the antioxidant Bostex ^® 362-C by Akron Dispersion Inc. as on the Field of the invention is generally known. Bostex 362-C is an aqueous mixture of ditridecythiodipropionate, 4-methylphenol and a reaction product of dicyclopentadiene and isobutylene, sodium dodecylbenzenesulfonate.

Representative physical properties of the preferred Sytrol-butadiene-acrylonitrile-latex binder are listed in Table 2.

Table 2

Example 3

To For comparative purposes, a latex binder was prepared using the same procedures and components as in Example 1 and 2, with the exception that the acrylonitrile monomer from the reactor charge was omitted for polymerization to the effect of the acrylonitrile monomer to determine. The weight percent of styrene, butadiene and dodecylmercaptan resulting in the reactor referred to as Example 3 Latex was added is shown in the following Table 3.

Table 3

The Physical properties of the latex of Example 3 are shown in Table 4 summarized.

Table 4

The resulting latex binders of Examples 1 to 3 were then on separate samples of non-cellulose nonwoven fibers of a further applied on the type described above using polyester. Naturally may be any of those well known in the art Be used methods such as soaking, immersion or spraying. Detailed descriptions of different devices and machining operations as well conditions for applying a latex binder to fibers, to make a fabric are in the literature of the nonwovens industry to find.

After this the latex binders are applied to the non-cellulose nonwoven fibers The latex binders were first air dried and then heat treated, to bind the non-cellulose fibers and a dimensionally stable To form nonwoven fabric. Naturally can The latex binders are also dried by passing over the surface several steam-heated vessels or be passed through a heating channel or furnace in which circulating hot air or infrared lamps used to dry the latex binder can be. The drying time hangs from a number of factors, such as the heat capacity of non-cellulose fibers, the type of heating, the oven temperature, the air speed (when circulating Air is used) and the rate at which the non-cellulose fibers through the oven or heating tunnel, from. The latex binders can be heat treated, for example, by passing the fibers for about 60 seconds at a temperature between about 104 and 121 ° C (about 220 and 250 ° F) heated and dried.

The fabrics of the present invention had improved tensile properties in water, as shown in Table 5. All of the stated performance characteristics were determined after conditioning the fabrics of the present invention for about 24 hours at TAPPI (Technical Association of the Pulp and Paper Industry) standard conditions of about 22 ° C (72 ° F) and about 50% relative humidity were. Tensile strength values, both wet and dry, were determined according to ASTM D 1117-80 entitled "Standard Methods of Testing Nonwoven Fabrics" published in the 1980 Annual Book of ASTM Standards. By following the ASTM standard test procedure, dry tensile measurements were made by passing 25 mm x 102 mm (1 inch wide and 4 inch long) strips of the fabric at a speed of 127 mm (5 inches) per minute with an initial jaw spacing of 76 3 inches) on an Instron. The wet tensile measurements were made in substantially the same manner as the dry tensile measurements except that the fabric strip was immersed in a water solution for about 30 seconds prior to testing on the Instron. Hold values are a quantitative measure of the fabric, as is well known in the textile industry. The grip values given are an average of the readings on a Thwing-Albert-Handle-O-Meter, using a square piece of fabric with a side length of 127 mm (5 inches). The fabrics were tested on the Handle-O-Meter in cross direction and running direction, and then an average was calculated. The amount of latex binder was calculated as follows. The weight of the fibers (F) was determined before applying the latex binder (L). After the latex binder (L) had been applied, the fibers were air dried, after which the final weight of the fabric (F + L) was determined. The latex binder content given below was then determined using the following equation: L / (F + L) × 100 Basis weight of the individual pure fiber of a certain type of fiber (Table 5) was kept constant. Pure 254 x 254 mm (10 in x 10 in) square samples were cut and sorted into weight ranges of only 0.1 gram deviation per 645 cm ² (100 square inches) within a given table.

Table 5

table Figure 5 shows the improved performance of a non-cellulose nonwoven fabric on which a latex binder described above is applied has been. As indicated in Table 5, were according to the present Invention Polyester fibers improved tensile properties lent in water. It is believed that similar to other fibers, such as acrylic fibers, polypropylene fibers, polyethylene glass fibers, Polyamide fibers and the like can be achieved.

Surprisingly For example, the non-cellulose nonwoven fabric of the present invention had improved tensile properties in water without a melamine-formaldehyde resin as an additive in the latex binder to provide the tensile properties to improve. Although typically acrylonitrile is used in a latex binder is to solvent resistance of the latex, for example perchlorethylene resistance, to improve, it turned out that the addition of an acrylonitrile monomer a negligible effect on the tensile properties in solvent, but a surprising one Had an effect on the tensile properties in water. Accordingly, lends an acrylonitrile monomer-containing latex binder according to the present invention Invention of a non-cellulose nonwoven fabric higher Water resistance properties. As explained above, another advantage of the present invention is that no melamine-formaldehyde resins are required, which is why the associated disadvantages, such as difficulties when mixed with a latex binder, quite high curing temperature and the presence of formaldehyde in the workplace and in the final product, do not occur.

Even though preferred embodiments herein of the invention, it is understood that the invention within the scope of the appended claims also can be put into practice differently.

Claims (20)

Non-cellulosic chemically bonded nonwoven fabric comprising a random array of non-cellulosic fibers and a substantially formaldehyde-free latex binder for bonding the non-cellulosic fibers, the latex binder being a latex binder which during the conventional drying / curing Cycle of the latex binder according to the Nash / HPLC method does not yield more than 0.7 parts of formaldehyde per million parts of latex binder and that by emulsion polymerization of a monomer mixture containing 50 to 70 wt .-% conjugated diene monomer and 16 to 50 wt. % vinyl substituted aromatic monomer, wherein the nonwoven fabric maintains at least about 78% of the transversely measured tensile strength when wet, characterized in that the monomer mixture for the binder further comprises at least about 6.7% by weight vinyl cyanide monomer and 15 contains up to 35% by weight of polymeric surfactant. The nonwoven fabric of claim 1, wherein the conjugated Diene monomer of piperylene, isoprene, 2,3-dimethyl-1,3-butadiene and 1,3-butadiene selected is. The nonwoven fabric of claim 1 or 2 wherein the vinyl substituted one aromatic monomer of α-methylstyrene, p-tert-butylstyrene, m-vinyltoluene, p-vinyltoluene, 3-ethylstyrene and styrene selected is. The nonwoven fabric of any one of claims 1 to 3, wherein the vinyl cyanide monomer of methacrylonitrile, ethacrylonitrile, phenylacrylonitrile and acrylonitrile selected is. Nonwoven fabric according to one of the preceding claims, wherein the polymeric surfactant is a resin containing about 25 to 27% by weight of a Styrene / acrylic acid / α-methylstyrene copolymer in water contains which was neutralized with about 6 to 7 wt .-% ammonium hydroxide. Nonwoven fabric according to any one of the preceding claims, wherein the percent elongation at break in the transverse direction in a wet test Condition 92% or more of the percentage elongation at break in the transverse direction in a test in a dry state. Nonwoven fabric according to any one of the preceding claims, wherein the non-cellulosic fibers are glass fibers or high polymer fibers are. The nonwoven fabric of claim 7, wherein the fibers are made from High polymer, selected from polyolefins, polyesters, acrylates and polyamides exist. The nonwoven fabric of claim 8, wherein the fibers are made from Polyolefin, selected of polypropylene, polyethylene, polybutylene and copolymers thereof, consist. The nonwoven fabric of claim 8, wherein the fibers are made from Polyester, selected of polyethylene terephthalate, liquid crystalline Polyesters and thermotropic polyesters. The nonwoven fabric of claim 8, wherein the fibers are acrylate, including any fiber-forming substance containing a long-chain synthetic polymer of at least 85 weight percent acrylonitrile units -CH ₂ CH (CN) -. Nonwoven fabric according to one of the preceding claims, which contains about 15 to 40 wt .-% of the latex binder. Nonwoven fabric according to any one of the preceding claims, wherein the emulsion polymerization in the presence of about 30 wt .-% of the performed polymeric surfactant has been. Nonwoven fabric according to any one of the preceding claims, wherein the monomer mixture comprises butadiene, styrene and acrylonitrile. A process which involves forming a latex binder and bonding a non-cellulosic nonwoven fabric comprising loose fibers with the binder to improve the wet tensile strength of the fabric; wherein the latex binder is prepared by emulsion polymerization of a monomer mixture containing 50 to 70 weight percent conjugated diene monomer and 16 to 50 weight percent vinyl substituted aromatic monomer, the latex binder being formaldehyde free in the sense that it is - according to the Nash / HPLC method determined - during the conventional cure / cure cycle of the latex binder does not deliver more than 0.7 part formaldehyde per million parts latex binder; characterized in that at least about 6.7% by weight of vinyl cyanide monomer is contained in the monomer mixture and that the polymerization is carried out in the presence of from 15 to 35% by weight of polymeric surfactant. The method of claim 15 wherein the polymeric surfactant an acrylic resin is solved that is neutralized. The method of claim 16 wherein the polymeric surfactant is a resin which is about 25 to 27% by weight of a styrene / acrylic acid / α-methylstyrene copolymer contains in water, with about 6 to 7 wt .-% ammonium hydroxide, potassium hydroxide or Calcium hydroxide was neutralized, and that an acid number from 100 to 300 and a weight average molecular weight of more than about 7,000. The method of claim 17, wherein the surfactant copolymer is neutralized with 6 to 7 wt .-% ammonium hydroxide. A process according to any one of claims 14 to 18, wherein the monomer mixture Butadiene, styrene and acrylonitrile. A process according to any one of claims 14 to 19, wherein the emulsion polymerization in the presence of about 30% by weight of the polymeric surfactant.