KR100365544B1 - Nonwoven fabric of non-cellulose fibers having improved wet tensile strength - Google Patents

Abstract

The present invention relates to nonwoven fabrics of chemically bonded non-cellulose fibers having improved underwater tensile properties. The fabric comprises randomly arranged non-cellulose fibers and a latex binder that is essentially free of formaldehyde. The latex binder binds non-cellulosic fibers and forms a nonwoven fabric having a wet tensile strength of at least 10% improvement over a comparative nonwoven with an intrinsically free formaldehyde free and latex binder free of vinyl cyanide monomer in the monomer mixture. At least 6.7% by weight of vinyl cyanide monomer.

Description

NONWOVEN FABRIC OF NON-CELLULOSE FIBERS HAVING IMPROVED WET TENSILE STRENGTH}

Nonwovens are webs or continuous sheets of mechanically woven fibers. The fibers can be laid in a random manner or aligned in one direction. The most widely used fibers are cellulose based, polyamide based, polyester based, polypropylene and polyethylene. Spun fibers that may be stretched are woven directly onto the porous belt by carding, air-laying or wet-laying, often using electrostatic charges. The sheets are then bonded to each other by a binder, which is then treated in an oven or calender to complete the bonding process.

Many methods have been developed for applying binders to randomly dispersed fibers. Typically, a thermoplastic or thermoset synthetic polymer latex is prepared and the loose web of fibers to be treated is immersed, saturated or sprayed therein using a special apparatus that takes into account the structural glaze of the web; A water based emulsion binder system is used, in which the treated web is dried, cured and bonded to an appropriate degree. Alternatively, an aqueous or solvent solution binder system of thermoplastic or thermosetting resin can be used to impregnate the fibrous web.

Another method involves applying thermoplastic or thermosetting powder to the fibers before or after making the web and passing the web through a hot roll or hot press to bond the fibers together. Alternatively, a thermoplastic fiber having a softening point lower than the softening point of the base fiber is dispersed inside the web of the base fiber, and a sufficient amount of heat and pressure is applied to soften the thermoplastic fiber and bond the fiber mesh together by using a heated roll.

Commonly used nonwoven latexes are those made from polymers such as butadiene-styrene, butadiene-acrylonitrile, vinyl acetate, acrylic monomers such as methyl acrylate, ethyl acrylate, methyl methacrylate and the like. While emulsion binders are the most popular method of forming nonwovens, the homopolymers, copolymers, and terpolymers used so far have one or more drawbacks. Synthetic polymers must have several properties in order to be useful as textile materials. Preferred properties include adequate tensile strength over a fairly wide temperature range, high modulus or stiffness under certain conditions, and good fabric properties such as toughness, operability and drape.

In order to impart improved underwater tensile properties to nonwoven non-cellulose products, it has been recognized that the use of self-crosslinked latex or latex with melamine formaldehyde resin is an acceptable practice. However, the system contains and releases formaldehyde during the drying / curing cycle. In addition, all commercially available magnetic crosslinking and melamine attached latexes require a temperature of at least 280 ° F, preferably at least 300 ° F, for proper crosslinking. However, since the melting point of many non-cellulose fibers is below the temperature required for proper crosslinking (eg polypropylene is about 250 ° F.), conventional latex cannot be used. Thus, polypropylene fibers have never been very successful in the nonwovens industry. The problem has been the special development of suitable latex binders that give acceptable tensile properties.

It is an object of the present invention to provide a nonwoven of chemically bonded non-cellulose fibers. Another object of the present invention is to provide a nonwoven fabric comprising a latex binder that is capable of developing maximum tensile properties at temperatures below the melt bonding temperature of randomly arranged non-cellulose fibers and non-cellulose fibers and is essentially formaldehyde free. It is. Another object of the present invention is to provide a nonwoven fabric comprising randomly arranged non-cellulose fibers and a latex binder that is capable of providing improved underwater tensile properties and is essentially formaldehyde free. Another object of the present invention is to provide a nonwoven fabric of chemically bonded non-cellulose fibers that is simple and economical to manufacture.

The present invention relates to nonwovens of chemically bonded non-cellulose fibers having improved underwater tensile properties. More specifically, the present invention relates to non-woven fabrics of non-cellulosic fibers that can provide improved underwater tensile properties and comprise latex binders that are essentially free of formaldehyde.

Summary of the Invention

In short, the present invention provides a nonwoven fabric comprising randomly arranged non-cellulose fibers and an essentially formaldehyde-free latex binder. Latex binders include polymer latexes prepared by emulsion polymerization of monomer mixtures in the presence of a polymerizable surfactant. The monomer mixture consists of conjugated diene monomers, vinyl substituted aromatic monomers and vinyl cyanide monomers. The conjugated diene monomer may be selected from piperylene, isoprene, 2,3-dimethyl-1,3-butadiene and 1,3-butadiene. The vinyl substituted aromatic monomer can be selected from α-methyl styrene, p-tert-butyl styrene, m-vinyl toluene, p-vinyl toluene, 3-ethyl styrene and styrene. The vinyl cyanide monomer may be selected from acrylonitrile, methacrylonitrile, ethacrylonitrile and phenylacrylonitrile.

The polymerizable surfactant is about 15-35% by weight based on dry latex. The polymerizable surfactant contains about 25-27% by weight of styrene / acrylic acid / α-methyl styrene copolymer in water neutralized with about 6-7% by weight of ammonium hydroxide.

In essence, formaldehyde-free latex binders contain at least about 6.7% by weight of vinyl cyanide monomer to form a nonwoven fabric that can bond the non-cellulose fibers and maintain a wet tensile strength of at least about 78% as measured in the transverse direction. It contains. Alternatively, the nonwoven fabric of the chemically bonded non-cellulose fibers is a wet tension that is essentially at least 10% improved over a comparative nonwoven fabric of the same type with a substantially identical monomer blend of formaldehyde free latex binder but without vinyl cyanide monomer. Has strength.

Suitable non-cellulose fibers include fibers made from glass fibers or high polymers. High polymers include polyolefins, polyesters, and acrylics, polyamides, and the like. Polyolefin fibers include polypropylene, polyethylene, polybutenes and copolymers thereof. Polyester fibers include, in addition to liquid crystalline polyesters, thermotropic polyesters and the like, any long chain synthetic polymer containing at least 85% by weight of esters of dihydric alcohols and terephthalic acid, such as polyethylene terephthalate. Acrylic fibers include any fiber forming material that contains a long chain synthetic polymer of at least 85% by weight of acrylonitrile units —CH ₂ CH (CN) —. Other types of non-cellulose fibers may also be used in accordance with the teachings of the present invention. High modulus fibers, also known as graphite fibers made from, for example, high modulus fibers, more commonly polyacrylonitrile, petroleum pitch or rayon, can also be used.

Nonwovens of non-cellulosic fibers are formed by providing a random arrangement of non-cellulose fibers. Next, a latex binder is essentially provided to the fiber which is free of formaldehyde. The latex binder is then heat treated to chemically bond the non-cellulose fibers and form a nonwoven fabric having dimensional stability.

Detailed description of the preferred embodiment

The present invention relates to nonwovens of chemically bonded non-cellulose fibers. The nonwoven fabric may be made from soft cloths such as diaper cover material, sanitary napkin cover material, medical gowns, masks, caps and drapes, and apparel interliners of clothing, furniture covers, quilts, water bed baffles and insulation. And hard and elastic fabrics such as padded fabrics.

The fabric of the present invention is made by forming a mat of non-cellulosic fibers that are chemically bonded and randomly arranged by a formaldehyde-free latex binder. The essentially formaldehyde free latex binder can chemically bond non-cellulose fibers and form a nonwoven fabric having dimensional stability. As is known in the art, the latex binder may be applied to a fibrous layer of spacing binder location patterns in randomly arranged non-cellulose fibers, or uniformly applied throughout the layer of non-cellulose fibers. have.

As used herein, the term “essentially formaldehyde free latex binder” refers to latex binder 100 during the usual drying / curing cycle of the latex binder as determined by the Nash / HPLC method (high performance liquid chromatography), as is known in the art. Refers to latex binders that release up to 0.7 parts per million (PPM) of formaldehyde; As used herein, the term “chemically bonded” refers to bonds that do not form as a result of heat treatment, such as by melt bonding, which is evidenced by physical changes in the fiber.

The non-cellulose fibers of the cloth may be glass fibers or fibers made from high polymers. Glass fibers are of a type well known in the art and are made from molten glass extruded through small pores and then spun at high speed. Suitable high polymers include polyolefins, polyesters, and acrylics, polyamides, and the like. Polyolefin fibers include polypropylene, polyethylene, polybutenes and copolymers thereof. Polyester fibers include, in addition to liquid crystalline polyesters, thermotropic polyesters, and the like, and any long chain synthetic polymer containing at least 85% by weight of esters of dihydric alcohols and terephthalic acid, such as polyethylene terephthalate. Acrylic fibers include any fiber forming material that contains a long chain synthetic polymer of at least 85% by weight of acrylonitrile units —CH ₂ CH (CN) —. Other types of non-cellulose fibers may also be used in accordance with the teachings of the present invention. High modulus fibers, also known as graphite fibers made from, for example, high modulus fibers, more commonly polyacrylonitrile, petroleum pitch or rayon, can also be used.

The non-cellulose fibers may be of any suitable size and may be randomly arranged in any suitable thickness depending on the desired end use of the nonwoven. Non-cellulose fibers typically have a length of about 0.25 to 2 inches and about 1.2-6 denier. The non-cellulosic fibers can be placed in a randomly overlapping state of overlapping up to a thickness of about 0.25 inches or less to form a mat of non-cellulose fibers. Non-cellulose fibers can be arranged by any conventional known method such as wet-laying, air-laying or carding.

After the non-cellulose fibers are randomly arranged as desired, a latex binder is applied to the fibers. The latex binder is used in an amount effective to ensure that the resulting fabric has sufficient strength and cohesion for the desired end use. The exact amount of latex binder used depends in part on the type of fiber, the weight of the fiber layer, the properties of the latex binder, and the like. For example, end uses requiring more rigid fabrics may use more binders. Typical contents of latex binders applied to non-cellulose fiber mats are about 15-40% by weight. As is known in the art, it is desirable to use a minimum amount of latex binder to obtain the minimum physical properties required for nonwovens such as tension, operability and the like.

Latex binders used in the present invention may be prepared by conventional known emulsion polymerization reactions using one or more ethylenically unsaturated monomers and polymerizable surfactants as disclosed herein, and conventional additional additives such as free radical initiators. Selective chain transfer agents, chelating agents and the like can be used as disclosed in US Pat. No. 5,166,259 by Schmeing and White.

Suitable ethylenically unsaturated monomers for emulsion polymerization include conjugated diene monomers, vinyl substituted aromatic monomers and vinyl cyanide monomers.

The conjugated diene monomers usually contain 4 to 10 carbon atoms, preferably 4 to 6 carbon atoms. Examples of specific diene monomers include pipeylene, isoprene, 2,3-dimethyl-1,3-butadiene and the like, preferably 1,3-butadiene. The amount of conjugated diene monomer used is about 50-70 wt%, preferably about 55-65 wt%, most preferably about 60 wt%. Vinyl substituted aromatic monomers usually contain a total of 8 to 12 carbon atoms. Examples of specific vinyl substituted aromatic monomers include α-methyl styrene, p-tert-butyl styrene, m-vinyl toluene, p-vinyl toluene, 3-ethyl styrene, and the like, preferably styrene. The amount of vinyl substituted aromatic monomer used is about 16-50% by weight, preferably about 27-50% by weight, most preferably about 27% by weight. When the amount of the vinyl substituted aromatic monomer in the present invention is greater than about 50% by weight, the latex is broken, unsuitable as a binder, and has unacceptable dry and wet tensile properties for non-cellulose nonwovens. Moreover, the more conjugated diene monomer added and the less vinyl substituted aromatic monomer, the softer hand properties and lower tensile properties are typically obtained in non-cellulose nonwovens. Similarly, the fewer conjugated diene monomers added and the more vinyl substituted aromatic monomers, the more rigid hand and higher tensile properties are typically obtained in non-cellulose nonwovens, resulting in reduced tensile properties and too non-cellulose nonwovens The amount is such that the latex binder does not form a continuous film.

The vinyl cyanide monomer may be methacrylonitrile, ethacrylonitrile, phenylacrylonitrile or the like, preferably acrylonitrile. The amount of vinyl cyanide monomer is at least about 6.7 wt%, preferably about 6.7-15 wt%, most preferably about 6.7-10 wt%.

The polymerizable surfactant is an acrylic resin neutralized in solution. In a preferred embodiment the polymerizable surfactant is dissolved in water neutralized with a base such as ammonium hydroxide, potassium hydroxide, calcium hydroxide and the like and has an acid value of about 100-300 and a weight average molecular weight greater than about 7,000. It is resin containing 27 weight% of styrene / acrylic acid / (alpha) -methyl styrene copolymer. Most preferably, the polymerizable surfactant is neutralized with about 6-7 wt% ammonium hydroxide, has an acid value of about 205 and a weight average molecular weight of about 8,500, and the average weight ratio of monomers α-methyl styrene, styrene and acrylic acid is weight parts. It is about 37:32:31.

Resins are prepared using small amounts of diethylene glycol monoethyl ether as solvent, according to the method described in US Pat. No. 4,529,787 to Schmidt et al., Incorporated herein by reference. Additional resins useful in the present invention can be prepared according to US Pat. No. 4,414,370 to Hamielec et al. And US Pat. No. 4,546,160 to Brandt et al., Which is incorporated herein by reference.

The amount of polymerizable surfactant added to the reactor is typically about 15-35% by weight, preferably about 26% by weight and most preferably about 30% by weight, based on dry latex.

Free radical initiators used to polymerize the various latex binder forming monomers include sodium persulfate, ammonium persulfate, potassium persulfate, and the like. Other free radical initiators that decompose or activate in applications used during polymerization, such as various peroxides, such as cumene hydroperoxide, dibenzoyl peroxide, diacetyl peroxide, can be used.

The optional chain transfer agent can be any suitable chain transfer agent commonly known in the art. Selective chain transfer agents include mercaptans such as alkyl and / or aryl mercaptans having from 8 to about 18 carbon atoms, preferably from about 12 to about 14 carbon atoms. Very preferred are tertiary alkyl mercaptans having 12 to 14 carbon atoms. Examples of suitable mercaptans include n-octyl mercaptan, n-dodecyl mercaptan, t-octyl mercaptan, t-dodecyl mercaptan, tridecyl mercaptan, tetradecyl mercaptan, hexadecyl mercaptan and the like and mixtures thereof. This includes. The amount of chain transfer agent is usually about 0.2 to about 2.5 parts, preferably 0.4 to about 0.9 parts, most preferably about 0.7 parts per 100 parts of monomer. In a preferred embodiment, the chain transfer agent is a dodecyl mercaptan chain transfer agent, such as Sulpole 120, available from Phillips 66.

Chelating agents may also be used during the polymerization reaction to tightly bind various metal impurities and to obtain uniform polymerization. The amount of such chelating agents is usually small, such as about 0.02 to about 0.08 parts, preferably about 0.05 parts, per 100 parts total monomer. Examples of suitable chelating agents include ethylene diamine tetraacetic acid, nitrilotriacetic acid, citric acid and its ammonium, potassium and sodium salts. Preferred chelating agents include chelating agents sold under the trade name "Hamp-ene" by the Hampshire Chemical Company.

In a preferred embodiment, the polymerization of ethylenically unsaturated monomers and polymerizable surfactants then occurs. The following examples illustrate the sequential addition of ethylenically unsaturated monomers and polymerizable surfactants to form latex binders.

Examples 1 and 2

According to the present invention, two separate latexes are prepared. Each latex contains about 20 gallons of volume and about 140 lb. of filling of deionized water, polymerizable surfactant, and hemp-ene. It is prepared by adding to a reactor having a retention capacity of latex. After addition of the polymerizable surfactant the reactor is evacuated to vacuum (about 20 inch Hg), purged with nitrogen and heated to the desired temperature. Ammonium persulfate is then added to the reactor as a solution of about 10% in deionized water.

Charges consisting of styrene, butadiene, acrylonitrile and dodecyl mercaptan are charged to the reactor in a uniform batch sequentially. The weight percent amounts of styrene, butadiene, acrylonitrile and dodecyl mercaptan added to the reactor for the latexes of Examples 1 and 2 are shown in Table 1.

Filling Example 1 (% by weight) Example 2 (% by weight) Styrene 26.9 33.6 butadiene 59.0 59.0 Acrylonitrile 13.4 6.7 Dodecyl mercaptan 0.7 0.7

Approximately 5 minutes after addition of ammonium persulfate to the reactor, a first batch of each latex is charged. Thereafter, additional batches are charged to the reactor at stepwise intervals of about 15 or 20 minutes. The batch may be added generally at any suitable stepped interval depending on the amount of latex binder to be polymerized. For example, it may be added in the same increments in steps up to 6 to 12 or more. After adding the last batch to the reactor, the reaction is monitored until the solids level of latex in the reactor indicates an acceptable conversion level. If the reaction rate is undesirably slow during the waiting period, an additional amount of ammonium persulfate is charged.

After reaching the desired conversion level, each latex is placed in a 60 gallon container and steamed and vacuum stripped. This process involves the addition of an antifoaming agent such as Drew L198. Along with the antioxidant Bostex 362-C supplied by Akron Dispersion Inc. is added a preservative, Kathon LX. Vostex 362-C is an aqueous mixture of ditridecyl thiodipropionate, 4-methyl phenol and the reaction product of dicyclopentadiene and isobutylene, sodium dodecylbenzene sulfonate.

Representative physical properties of the preferred styrene-butadiene-acrylonitrile latex binders are shown in Table 2.

Property Example 1 Example 2 Solid content (% by weight) 45.5 47.3 Wet Ingredient Weight / gallon (lbs) 8.48 8.47 Brookfield Viscosity (cps) 36 48 pH 7.5 7.5 Surface tension (dynes / cm) 41.3 42.6 Glass transition temperature (° C), measured by DSC ¹ -20 -24 Particle charge Anionic Anionic Particle size (Å) 619 727 ¹ Differential Scanning Calorimetry

Example 3

For comparison, latex binders are prepared using the same procedures and components as in Examples 1 and 2 except that the acrylonitrile monomer was subtracted from the reactor charge for polymerization to determine the effect of the acrylonitrile monomer. The weight percent amounts of styrene, butadiene and dodecyl mercaptan added to the reactor for the latex of Example 3 are shown in Table 3 below.

Filling Example 3 (% by weight) Styrene 40.3 butadiene 59.0 Dodecyl mercaptan 0.7

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

Property Example 3 Solid content (% by weight) 45.9 Wet Ingredient Weight / gallon (lbs) 8.46 Brookfield Viscosity (cps) 37 pH 7.5 Surface tension (dynes / cm) 42.7 Glass transition temperature (° C), measured by DSC ¹ -26 Particle charge Anionic Particle size (Å) 507 ¹ Differential Scanning Calorimetry

The resulting latex binder of Examples 1-3 is then applied to individual samples of the nonwoven non-cellulose fibers of the type described above using polyester. Any suitable known technique such as saturation, dipping or spraying may also be used. Reference is made to the nonwovens industry literature for a detailed description of the various devices and processing structures and conditions for applying a latex binder to fibers to form fabrics.

After the latex binder is applied to the nonwoven non-cellulose fibers, the latex binder is air dried and then heat treated to bond the non-cellulose fibers and form a nonwoven fabric having dimensional stability. The latex binder may also be dried by passing the latex binder over the surface of several steam heated cans, or through a heating tunnel or oven where a circulating hot air or infrared lamp can be used to dry the latex binder. . Drying time will be a function of several factors such as heat capacity of the non-cellulose fibers, heating type, oven temperature, air velocity (if circulating air is used), and the rate at which the non-cellulose fibers pass through the oven or heating tunnel. For example, the latex binder can be heat treated by heating and drying the fibers at a temperature of about 220-250 ° F. for approximately 60 seconds.

The fabric according to the present invention shows improved underwater tensile performance as shown in Table 5. All reported performance is measured after conditioning the fabric according to the invention for about 24 hours at the Technical Association of the Pulp and Paper Industry (TAPPI) standard conditions of approximately 72 ° F. and approximately 50% relative humidity. Dry and wet tension values are measured according to ASTM D 1117-80, entitled "Standard Test Methods for Nonwovens," published in the ASTM Standard Yearbook of 1980. Dry tension is measured using a piece of cloth 1 inch wide by 4 inches long, tensioned at a rate of 5 inches per minute on an Instron 3 inch jaw interval, according to the ASTM standard test method. Wet tension is measured in substantially the same manner as the dry tension measurement method, except that the piece of cloth is immersed in an aqueous solution for about 30 seconds before testing on instron. Hand value is a quantitative measure of cloth, known in the textile industry. The reported hand value is the average of the measurements taken on a Swing Albert Handle-O-Meter using a piece of cloth of 5 square inches. The fabric is tested on the cross-machine and machine directions on a handle-O-meter and averaged. The amount of latex binder is calculated as follows. The weight of the fiber (F) is obtained before applying the latex binder (L). After applying the latex binder (L), the fibers are air dried and the final weight (F + L) of the fibers is obtained. The latex binder content reported below is determined according to the formula L / (F + L) × 100. Each net fiber basis weight (Table 5) of the individual fibers is kept constant. Ten inches by ten inches of pure fiber samples are cut and sorted into weight ranges with a deviation of only 0.1 grams per 100 square inches within a particular table.

Example One 2 3 Air drying heat treatment 1 minute @ 250 ° F 1 minute @ 250 ° F 1 minute @ 250 ° F Amount of latex binder 42.6 wt% 39.4 wt% 40.3 wt% Fiber Denier Fiber Length Polyester 1.21.5 inch Polyester 1.21.5 inch Polyester 1.21.5 inch Hand value (grams) 42.3 35.0 Cross-direction dry test tension (grams)% elongation at break 605.845.8 555.041.8 532.551.4 Lateral-Wet Wetting Test Tension (grams)% Elongation at Break Water Water431.642.5 Water389.142.4 Lateral-Wet Wetting Test Tension (grams)% Elongation at Break Perchlorethylene38.99.9 Perchlorethylene25.711.2 Perchlorethylene24.217.1

Table 5 describes the improved performance of the non-cellulose nonwovens with the latex binder described above. As explained in Table 5, improved underwater tensile properties are obtained by the present invention for polyester fibers. It is believed that similar comparables can be obtained for other fibers such as acrylic fibers, polypropylene fibers, polyethylene fiberglass fibers, polyamide fibers and the like.

Surprisingly, the non-cellulose nonwovens according to the present invention exhibit improved underwater tensile properties without requiring melamine formaldehyde resin as an additive to the latex binder in order to improve the tensile properties. Although acrylonitrile is commonly used in latex binders to improve latex solvent resistance, such as perchloroethylene resistance, the addition of acrylonitrile monomers has a negligible effect on the tensile properties in solvents but a surprising effect on the tensile properties in water. Was found. Thus, the acrylonitrile monomer containing the latex binder according to the present invention imparts improved water resistance to non-cellulose nonwovens. As described above, an additional advantage of the present invention is that it does not require melamine formaldehyde resins, which is why it is difficult to mix with latex binders, for example, it is difficult to mix with latex binders, requires quite high temperatures to cure and formaldehyde There is no supply to the site and to the end use product.

It is now understood that preferred embodiments of the present invention have been mentioned, or that they may be included within the scope of the appended claims.

Claims (20)

Nonwoven fabric of chemically bonded non-cellulosic fibers with improved wet tensile properties and containing: essentially a wet tensile strength of at least 10% over a comparative nonwoven having a latex binder that is essentially free of formaldehyde and free of vinyl cyanide monomers in the monomer mixture; Nonwovens with: Randomly arranged non-cellulose fibers; And Emulsion polymerization of a monomer mixture comprising 50-70% by weight of conjugated diene monomer, 16-50% by weight of vinyl substituted aromatic monomer and at least 6.7% by weight of vinyl cyanide monomer in the presence of 15-35% by weight of polymerizable surfactant. A latex binder that is essentially formaldehyde free and is prepared by and for bonding the non-cellulose fibers. The method of claim 1, wherein the essentially formaldehyde-free latex binder, when measured by Nash / HPLC method, forms less than 0.7 parts per million (PPM) of formaldehyde per million parts of latex binder during a typical drying / curing cycle of the latex binder. A nonwoven fabric that releases latex binders. Claim 3 was abandoned upon payment of a set-up fee. 3. The nonwoven fabric of claim 2 wherein the latex binder is prepared by emulsion polymerization of a monomer mixture comprising conjugated diene monomers, vinyl substituted aromatic monomers and vinyl cyanide monomers in the presence of a polymerizable surfactant. Claim 4 was abandoned upon payment of a set-up registration fee. 4. The nonwoven fabric of claim 3, wherein said conjugated diene monomer is selected from the group consisting of pipeylene, isoprene, 2,3-dimethyl-1,3-butadiene and 1,3-butadiene. Claim 5 was abandoned upon payment of a set-up fee. The nonwoven fabric of claim 4 wherein said vinyl substituted aromatic monomer is selected from the group consisting of α-methyl styrene, p-tert-butyl styrene, m-vinyl toluene, p-vinyl toluene, 3-ethyl styrene, and styrene. Claim 6 was abandoned upon payment of a set-up fee. 6. The nonwoven fabric of claim 5 wherein said vinyl cyanide monomer is selected from the group consisting of methacrylonitrile, ethacrylonitrile, phenylacrylonitrile and acrylonitrile. The nonwoven fabric of claim 3, wherein the polymerizable surfactant is a resin containing 25-27 wt% styrene / acrylic acid / α-methyl styrene copolymer in water neutralized with about 6-7 wt% ammonium hydroxide. The nonwoven fabric of claim 1 wherein the percent elongation at break of the transverse wet test is at least 92% of the percent elongation at break of the transverse drying test. Claim 9 was abandoned upon payment of a set-up fee. 4. The nonwoven fabric of claim 3, wherein said non-cellulose fibers are selected from the group consisting of glass fibers or fibers made of high polymers. Claim 10 was abandoned upon payment of a set-up fee. 10. The nonwoven fabric of claim 9, wherein said high polymer is selected from the group consisting of polyolefins, polyesters, acrylics, and polyamides. Claim 11 was abandoned upon payment of a set-up fee. 11. The nonwoven fabric of Claim 10, wherein said polyolefin is selected from the group consisting of polypropylene, polyethylene, polybutene, and copolymers thereof. Claim 12 was abandoned upon payment of a set-up fee. 11. The nonwoven fabric of claim 10, wherein said polyester comprises polyethylene terephthalate, liquid crystalline polyester, and thermotropic polyester. Claim 13 was abandoned upon payment of a set-up fee. The nonwoven fabric of claim 10, wherein the acryl comprises any fiber forming material containing a long chain synthetic polymer consisting of at least 85% by weight of acrylonitrile units —CH ₂ CH (CN) —. Claim 14 was abandoned upon payment of a set-up fee. 4. The nonwoven fabric of claim 3, containing 15-40% by weight of latex binder. Claim 15 was abandoned upon payment of a set-up fee. The nonwoven fabric of claim 3 wherein the emulsion polymerization is carried out in the presence of 15-35% by weight of polymerizable surfactant. Claim 16 was abandoned upon payment of a set-up fee. 4. The nonwoven fabric of claim 3 wherein the emulsion polymerization is carried out in the presence of 30% by weight polymerizable surfactant. Nonwoven fabric of chemically bonded non-cellulosic fibers with improved wet tensile properties and containing: essentially a wet tensile strength of at least 10% over a comparative nonwoven having a latex binder that is essentially free of formaldehyde and free of vinyl cyanide monomers in the monomer mixture; Nonwovens with: Randomly arranged non-cellulose fibers; And 50-70% by weight in the presence of 15-35% by weight of polymerizable surfactant containing 25-27% by weight of styrene / acrylic acid / α-methyl styrene copolymer in water neutralized with 6-7% by weight of ammonium hydroxide Prepared by emulsion polymerization of a monomer mixture comprising conjugated diene monomers, 16-50% by weight of vinyl substituted aromatic monomers and at least 6.7% by weight of vinyl cyanide monomers, essentially formaldehyde, for bonding the non-cellulose fibers. Free latex binder. 18. The nonwoven fabric of claim 17, wherein the monomer mixture comprises butadiene, styrene, and acrylonitrile. A method of improving the wet tensile strength of a nonwoven fabric of non-cellulose fibers comprising an essentially formaldehyde-free latex binder, comprising the following steps, wherein the nonwoven fabric is essentially formaldehyde free and contains a vinyl cyanide monomer in the monomer mixture. To achieve a wet tensile strength of at least 10% over a comparative nonwoven with a latex free binder: 50-70% by weight in the presence of 15-35% by weight of polymerizable surfactant containing 25-27% by weight of styrene / acrylic acid / α-methyl styrene copolymer in water neutralized with 6-7% by weight of ammonium hydroxide Providing a monomer mixture comprising a conjugated diene monomer and 16-50% by weight of a vinyl substituted aromatic monomer; Adding at least 6.7% by weight of vinyl cyanide monomer to the monomer mixture; And Emulsion polymerizing the monomer mixture. The method of claim 19 wherein the monomer mixture comprises butadiene, styrene and acrylonitrile.