MXPA98003216A - Formaldehyde-free compositions for non-woven material - Google Patents

Abstract

The present invention relates to: A formaldehyde-free curable composition for binding non-woven material, comprising: (a) a polyacid comprising at least two carboxylic acid groups, anhydride groups or the polyacid salts thereof; compound of active hydrogen containing at least two active hydrogen groups selected from the group consisting of hydroxyl, primary amino, secondary amino and mixtures thereof, and (c) one or more compounds selected from the group consisting of cyanamide, dicyanamide, 1, 2-mono- or di- (C 1 -C 6 alkyl) substituted-3-cyanoguanidines such as ethyl-3-cyanoguanidine, 1,2-diethyl-3-cyanoguanidine and 1,2-diisopropyl-3-cyanoguanidine, and 1,2 -mono- or di- (C6-C12 aryl) substituted -3-cyanoguanidines, such as phenyl-dicyandiamide, and optionally (d) an accelerator, wherein the scale of the number of equivalents of said acid-carboxylic acid groups, anhydride groups and salts thereof at number of equivalents of said active hydrogen groups is from 1 / 0.01 to 1/3, and wherein said carboxylic acid groups, anhydride groups or salts thereof are neutralized to a point of less than 35% by weight with a fixed base. The accelerator can be a phosphorus and / or fluoroborate compound. The compositions allow to manufacture with flexibility through lower curing temperatures

Description

Formaldehyde-Free Compositions For Nonwoven Material This invention relates to formaldehyde-free compositions for nonwoven material. In particular, although not exclusively, the present invention relates to formaldehyde-free compositions suitable for binding heat-resistant, glass fiber or mineral non-woven material. Heat resistant nonwoven fiberglass material is composed of fibers that can be consolidated by purely mechanical means such as, for example, treatment with a polymeric binder; or by a combination of mechanical and chemical means before, during or after the formation of the nonwoven material. The polymeric binder is often entangled by reaction with formaldehyde-producing resins. However, in some countries there is currently legislation limiting formaldehyde emissions as well as proposed legislation that may also limit or eliminate formaldehyde emissions; in other countries the pressure for environmental protection has increased in such a way to the point where similar legislation is devised. Accordingly, there is a continuing and growing need for compositions that do not emit formaldehyde in the interlacing.

The prior art has disclosed a number of compositions for non-woven material, which do not emit formaldehyde in the interlacing. US-A-5318990 and EP-A-0583086 disclose formaldehyde-free compositions, based on combinations of polyacids and polyols, which can be used as binders for the heat resistant nonwoven material. However, said compositions essentially depend on the presence of a phosphorous accelerator to ensure effective cure. EP-A-0672720 discloses formaldehyde-free binding, impregnating or coating compositions which are described as being useful for bonding the non-woven material of glass fiber, mineral fiber or polyester fiber. The compositions are based on A) a polymer derived from 2 to 100% by weight of an acid anhydride or. ethylenically unsaturated acid and B) a polyol selected from certain triazine derivatives, triazinetrione derivatives or cyclohexyl or benzene derivatives. Although such compositions essentially do not require the presence of an accelerator to effect cure, they tend to require relatively high temperatures to effect bonding, thereby limiting the flexibility of the manufacturing process and increasing manufacturing costs. An object of the present invention is to provide formaldehyde-free compositions which can be used as binder, impregnation or coating compositions for non-woven material but which essentially do not require the presence of an accelerator, and can be bonded at relatively low temperatures in comparison with, for example, those disclosed in EP-A-0672720. In accordance with the present invention, there is provided a formaldehyde-free curable composition comprising: (a) a polyacid comprising at least two carboxylic acid groups, anhydride groups or the polyacid salts thereof; (b) an active hydrogen compound containing at least two active hydrogen groups selected from the group consisting of hydroxyl, primary amino, secondary amino and mixtures thereof; and (c) one or more compounds selected from the group consisting of cyanamide, dicyandiamide, 1,2-mono or di- (Ci-Cg alkyl) substituted-3-cyanoguanidines such as ethyl-3-cyanoguanidine, 1,2-diethyl -3-cyanoguanidine and 1,2-diisopropyl-3-cyanoguanidine, and 1,2-mono- or di (C6-C12 aryl) substituted-3-cyanog anidines, such as phenyl-dicyandiamide. Preferably component (c) is cyanamide or dicyandiamide or a mixture thereof, more preferably component (c) is dicyandiamide; where the scale of the number of equivalents of said carboxylic acid groups, anhydride groups or salts thereof to the number of equivalents of said active hydrogen groups is from 1/1 to 1/3, and wherein said carboxylic acid groups, anhydride groups or salts thereof are neutralized to a point of less than 35% by weight with a fixed base. It has been found that the compositions of the present invention adequately cure at temperatures significantly below certain compositions described in EP-A-0672720, and can be used as binder, impregnation and coating compositions for nonwoven material. For example, it has been found that the compositions of the present invention, when used as binders for non-woven, heat-resistant glass fiber, can be effectively cured at temperatures significantly below the temperatures required for effective cure. of certain compositions of EP-A-0672720, without any significant harmful effect on the binding properties in the non-woven material. This reduction in curing temperatures offers the manufacturer of non-woven, heat-resistant fiberglass material a more flexible manufacturing process and the possibility of reducing manufacturing costs. For example, breakage of the non-woven material occurs to a lesser extent during manufacturing when a binder with low interlacing temperature is used, thus reducing the possibility of manufacturing interruptions. In another aspect, the present invention provides a method for bonding a heat resistant nonwoven material, or heat resistant fibers thereof, comprising: (I) contacting said nonwoven material or its fibers with a curable composition as defined previously, and (II) heating said curable composition to an elevated temperature, whose temperature is sufficient to effect the cure. Preferably, the curing is carried out at a temperature of 120 ° C to 300 ° C, more preferably less than 200 ° C. In another aspect, the present invention provides a non-woven material comprising an entangled composition obtained by curing a composition as defined above. Preferably, the non-woven material is heat resistant and preferably comprises glass or mineral fibers. Although an accelerator is not an essential component for obtaining adequate interlacing of the composition of the present invention, it has been found that the presence of an accelerator can offer other significant advantages, such as a high interlacing density in the cured composition and a low in the water susceptibility of the cured composition. Accordingly, in a particular embodiment of the present invention, there is provided a formaldehyde-free curable aqueous composition, comprising: (a) a polyacid comprising at least two carboxylic acid groups, anhydride groups or the polyacid salts thereof; (b) an active hydrogen compound containing at least two active hydrogen groups selected from the group consisting of hydroxyl, primary amino, secondary amino and mixtures thereof; (c) one or more compounds selected from the group consisting of cyanamide, dicyandia, 1,2-mono- or di- (Cx-Cg alkyl) substituted-3-cyanoguanidines such as ethyl-3-cyanoguanidine, 1,2-diacyl -3-cyanoguanidine and 1,2-diisopropyl-3-cyanoguanidine, and 1,2-mono- or di- (C6-C12 aryl) substituted -3-cyanoguanidines such as phenyl-dicyandiamide, preferably the component ® is cyanamide or dicyandiamide or a mixture thereof, more preferably component (c) is dicyandiamide; and (d) an accelerator; wherein the scale of the number of equivalents of said carboxylic acid groups, anhydride groups or salts thereof to the number of equivalents of said active hydrogen groups is from 1 / 0.1 to about 1/3, and wherein said carboxylic acid groups, groups Anhydrides or salts thereof are neutralized to a point of less than 35% by weight with a fixed base. Suitable accelerators are well known in the art, but preferably the accelerator is a phosphorus or fluoroborate compound or a mixture thereof. The composition of the present invention is preferably in the form of an aqueous composition comprising components (a), (b) and (c), and optionally (d), but, in another embodiment, it may also be in the form of solids, such as as granules or dry powder, comprising the same components. A dry powder can be manufactured by drying by spraying the aqueous form, and other techniques for making powders can also be used. The formaldehyde-free curable composition of this invention is a substantially non-interlaced or substantially thermoplastic composition when applied to the substrate, although low levels of deliberate or adventitious interlacing may be present. Upon heating the binder, the curing is effected either sequentially, after the binder is dried if it is in aqueous form, or concurrently if the binder is in dry form. As used herein, curing is defined as a structural or morphological change that is sufficient to alter the properties of a porous and flexible substrate, to which an effective amount of polymeric binder has been applied such as, for example, covalent chemical reaction, grouping or ionic interaction, improved adhesion to the substrate, investment or phase transformation, and hydrogen bonding. By "formaldehyde-free" it is meant that the composition substantially does not have formaldehyde, and does not release substantial formaldehyde as a result of drying and / or curing. Typically, less than one part per million formaldehyde, based on the weight of the composition, is present in a formaldehyde-free composition. To minimize the formaldehyde content of the composition it is preferred, when preparing a polymer-containing formaldehyde-free curable composition, to use polymerization adjuncts such as, for example, initiators, reducing agents, chain transfer agents, biocides, surfactants and similar, which themselves do not have formaldehyde, do not generate formaldehyde during the polymerization process and do not generate or emit formaldehyde during the treatment of heat resistant nonwoven material. The formaldehyde-free curable compositions contain a polyacid. The polyacid must be sufficiently non-volatile, so that it will remain substantially available for reaction with the compound (b) in the composition during the heating and curing operations. When the polyacid is a compound with a molecular weight of about 300, carrier of at least two carboxylic acid groups, anhydride groups or salts thereof, the polyacid typically is for example citric acid, butane tricarboxylic acid and cyclobutane tetracarboxylic acid. When the polyacid is a polymeric polyacid, the polyacid is typically, for example, a polyester containing at least two carboxylic acid groups and an oligomer or addition polymer containing at least two acid functional, carboxylic, copolymerized monomers. The polymeric polyacid is preferably an addition polymer formed from at least one ethylenically unsaturated monomer. The addition polymer may be in the form of a solution of the addition polymer in an aqueous medium such as, for example, an alkali-soluble resin that has been solubilized in a basic medium.; in the form of an aqueous dispersion such as, for example, an emulsion polymerized dispersion; or in the form of an aqueous suspension. "Aqueous" here includes water and mixtures substantially composed of water and miscible solvents in water. The addition polymer must contain at least two carboxylic acid groups, anhydride groups or salts thereof. Ethylenically unsaturated carboxylic acids such as, for example, methacrylic acid, acrylic acid, crotonic acid, fumaric acid, maleic acid, 2-methyl maleic acid, itaconic acid, 2-methyl itaconic acid, alpha glutaric acid, beta-methylene, monoalkyl maleates and monoalkyl fumarates; ethylenically unsaturated anhydrides such as, for example, maleic anhydride, itaconic anhydride, acrylic anhydride and methacrylic anhydride; and salts thereof, at a level of about 1% to 100% by weight, based on the weight of the addition polymer. Additional ethylenically unsaturated monomers may include acrylic ester monomers that include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, butyl methacrylate, isodecyl methacrylate, hydroxyethyl, hydroxyethyl methacrylate and hydroxypropyl methacrylate, acrylamide or substituted acrylamides; styrene or substituted styrenes; butadiene; vinyl acetate or other vinyl esters; and acrylonitrile or methacrylonitrile. The addition polymer containing at least two carboxylic acid groups, anhydride groups or salts thereof may have a molecular weight of from about 300 to about 10,000,000. A molecular weight of about 1000 to about 250,000 is preferred. When the addition polymer is an alkali soluble resin having a content of carboxylic acid, anhydride or salts thereof, from about 5% to about 30% by weight, based on the total weight of the addition polymer, a weight is preferred molecular weight from about 7,000 to about 100,000, since the higher molecular weight alkali soluble resins lead to compositions that may exhibit excessive viscosity. When the addition polymer is in the form of an aqueous dispersion or suspension and low levels of gel or pre-interlacing content are desired, low levels of multi-ethylenically unsaturated monomer such as, for example, allyl methacrylate, diallyl phthalate, , 4-butylene-glycol-dimethacrylate and 1,6-hexanedioldiacrylate, can be used at a level of from about 0.01% to about 5% by weight, based on the weight of the acrylic emulsion copolymer. When the addition polymer is in the form of an aqueous dispersion, the particle diameter of the addition polymer can be from about 80 nanometers to about 1000 nanometers, as measured using a Broo haven BI-90 particle meter, which employs a technique of light scattering. However, polymodal particle size distributions, such as those described in US Pat. Nos. 4,384,056 and 4,539,361, can be employed and are within the scope of the present invention. When the addition polymer is in the form of an aqueous dispersion, the addition polymer particles can be made of two or more mutually incompatible copolymers. These mutually incompatible copolymers can be present in various morphological configurations such as, for example, core / shell particles, core / shell particles with shell phases that incompletely encapsulate the core, core / shell particles with a multiplicity of nuclei, and Interpenetrating network particles. The addition polymer can be prepared by means of solution polymerization, emulsion polymerization or suspension polymerization techniques for ethylenically unsaturated polymerizing monomers, which are well known in the art. When it is desired to use emulsion polymerization, anionic and nonionic surfactants or mixtures of these may be used. The polymerization can be carried out by various means such as, for example, with all the monomers in the reaction vessel at the beginning of the polymerization reaction, with a portion of the monomer in emulsified form present in the reaction vessel at the beginning of the reaction. polymerization reaction, and with an emulsion polymer seed of small particle size present in the reaction vessel at the beginning of the polymerization reaction. The polymerization reaction for preparing the addition polymer can be initiated by various methods known in the art such as, for example, using the thermal decomposition of an initiator and using an oxidation reduction reaction ("redox reaction") to generate radicals free to effect the polymerization. In another embodiment, the addition polymer can be formed in the presence of phosphorus-containing chain transfer agents such as, for example, hypophosphorous acid and its salts, as disclosed in U.S. Pat. No. 5,077,361, so as to incorporate the polyacid component and the phosphorus-containing accelerator in the same molecule. Chain transfer agents such as mercaptans, polymercaptans and halogen compounds can be used in the polymerization mixture to moderate the molecular weight of the acrylic emulsion copolymer. Generally, up to about 1% by weight, based on the weight of the polymeric binder, of (C4-C20) alkyl mercaptans / mercaptopropionic acid or mercaptopropionic acid esters can be used.

The carboxyl groups of the polyacid component of the formaldehyde-free curable aqueous composition are neutralized with fixed base to a point of less than about 35%, calculated on a base of equivalents. Upon contacting the addition polymer component before, during or after the preparation of the curable aqueous composition, the addition polymer containing two carboxylic acid groups, anhydride groups or salts thereof, defined herein as neutralization, with a fixed base, it is required before the treatment of a non-woven substrate. The neutralization of less than about 35% of the carboxylic acid groups, calculated on a base of equivalents, with a fixed base is required. The neutralization of less than about 20% of the carboxylic acid groups, calculated on a base of equivalents, with a fixed base is preferred. Still more preferred is the neutralization of less than about 5% of the carboxylic acid groups, calculated on a base of equivalents, with a fixed base. When the average ester of a dicarboxylic acid or the anhydride of a dicarboxylic acid is used, the acid equivalents are calculated to be the same as those corresponding to the dicarboxylic acid. As used herein, "fixed base" or "permanent base" refers to a monovalent base which is substantially not volatile under the conditions of the treatment such as, for example, sodium hydroxide, potassium hydroxide, sodium carbonate or hydroxide. t-butylammonium. The fixed base must be sufficiently non-volatile so that it remains substantially in the composition during the heating and curing operations. Volatile bases such as, for example, lower volatile alkyl amines or ammonia, do not function as the fixed base of this invention but can be used in addition to the fixed base; they do not contribute to the required degree of neutralization by a fixed base. Fixed multivalent bases such as, for example, sodium carbonate, may tend to destabilize an aqueous dispersion if the addition polymer is used in the form of an aqueous dispersion, but may be used in a smaller amount. The formaldehyde-free curable composition also contains an active hydrogen compound containing at least two active hydrogen groups selected from the group consisting of hydroxyl, primary amino, secondary amino and mixtures thereof The active hydrogen compound must be sufficiently non-volatile so that it remains substantially available for reaction with the polyacid in the composition, during heating and curing operations The active hydrogen compound can be a compound with a molecular weight less than about 1,000, carrying at least two groups of active hydrogen such as, for example, ethylene glycol, glycerol, pentaerythritol, trimethylolpropane, sorbitol, sucrose, glucose, resorcinol, catechol, pyrogallol, glycolated ureas, 1,4-cyclohexanediol, monoethanolamine, diethanolamine, triethanolamine and certain reactive polyols such as, for example, β-hydroxyalkylamides such as, for example, bis- [N, N] -di (ß-hydroxyethyl)] adipamide, and can be prepared in accordance with the teachings of U.S. Pat. 4,076,917, incorporated herein by reference, or may be an addition polymer with a molecular weight greater than about 1,000 containing at least two active hydrogen groups such as, for example, polyvinyl alcohol, partially hydrolyzed polyvinyl acetate and homopolymers or copolymers of hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, dimethylaminoethyl methacrylate and dimethylaminopropyl methacrylamide. The scale of the number of carboxy equivalents, anhydride or salts thereof of the polyacid to the number of equivalents of the active hydrogen in the active hydrogen compound is about 1 / 0.01 to about 1/3. An excess of the active hydrogen equivalents in the active hydrogen compound is preferred. The most preferred scale of the number of carboxy equivalents, anhydride or its salts in the polyacid to the number of equivalents of the active hydrogen in the active hydrogen compound is from about 1 / 0.1 to about l / l. The most preferred scale of the number of equivalents of carboxy, anhydride or salts thereof in the polyacid to the number of equivalents of the active hydrogen in the active hydrogen compound is from about 1 / 0.2 to about 1 / 0.8.

The formaldehyde-free curable composition preferably contains about 10% by weight or less, more preferably less than about 10% but more than about 2% by weight, and more preferably about 3% to about 8% by weight , based on the total weight of (a), (b) (c), of one or more compounds selected from the group consisting of cyanamide, dicyandiamide, 1,2-mono or di- (Cx-Cg alkyl) substituted-3 -cyanoguanidines such as ethyl-3-cyanoguanidine, 1,2-diethyl-3-cyanoguanidine and 1,2-diisopropyl-3-cyanoguanidine, and 1,2-mono or di- (C6-C12 aryl) substituted-3-cyanoguanidines , such as phenyl-dicyandiamide. Preferably component (c) is cyanamide or dicyandiamide or a mixture thereof, more preferably component (c) is dicyandiamide. The formaldehyde-free curable composition may also contain an accelerator (d) which is preferably present in an amount of 10% or less, more preferably from 0.01 to 10%, even more preferably from 0.1% to 5%, and more preferably from 0.5% to 2% by weight, based on the combined weight of the polyacid and the active hydrogen compound. Preferably, the accelerator is a phosphorous compound or a fluoroborate compound or a mixture of these compounds. Compound (d) can be, for example, hypophosphorous acid, sodium hypophosphite, sodium phosphite, potassium phosphite, disodium pyrophosphate, tetrasodium pyrophosphite, sodium tripolyphosphate, potassium tripolyphosphate, potassium phosphate, fluoboric acid; an alkali metal fluorobate salt such as sodium tetrafluoroborate or potassium tetrafluoroborate; a multivalent metal fluoroborate salt such as calcium tetrafluoroborate, magnesium tetrafluoroborate or zinc tetrafluoroborate; and ammonium tetrafluoroborate or a mixture of two or more of these compounds. The formaldehyde-free curable compositions may additionally contain conventional treatment components such as, for example, emulsifiers, pigments, fillers, anti-migration aids, curing agents, coalescents, wetting agents, biocides, plasticizers, oragnosilanes, anti-foaming agents, dyes, waxes and antioxidants. The formaldehyde-free curable composition can be prepared by mixing the compound (a), the compound (b) and the compound (c), and the optional compound (d), using conventional mixing techniques. As disclosed above, the carboxyl groups of the polyacid can be neutralized to a point of less than about 35% with a fixed base before, during or after mixing to provide the aqueous composition. The neutralization can be carried out partially during the formation of the polyacid. In one embodiment of this invention, the formaldehyde-free curable composition can be used as a binder for heat resistant nonwoven material such as, for example, nonwoven material containing heat resistant fibers such as, for example, aramid fibers , ceramic fibers, metallic fibers, carbon fibers, polyimide fibers, certain polyester fibers, rayon fibers and glass fibers. Here we refer to "heat resistant fibers" to fibers that are not substantially affected by exposure to temperatures above about 120 ° C. The heat resistant nonwoven material may also contain fibers that are not in themselves resistant to heat such as, for example, certain polyester fibers, rayon fibers, nylon fibers and superabsorbent fibers, as long as they do not affect material and adversely the development of the substrate. The formaldehyde-free curable composition can be applied to the non-woven material or by means of conventional techniques such as, for example, spraying with or without air, filling, saturation, roll coating, curtain coating, Dutch shredder stack deposition and coagulation, or as a powder. The aqueous formaldehyde-free composition, after being applied to a non-woven material, is heated to effect drying and curing. The duration and temperature of heating will affect the rate of drying, processability and manageability and the development of properties of the treated substrate. The heat treatment can be carried out from about 120 ° C to about 300 ° C for a period of time between about three seconds to about 15 minutes; the treatment is preferred from about 150 ° C to about 200 ° C. The drying and curing functions can be carried out in two or more different stages, if desired. For example, the composition may first be heated at a temperature and for a sufficient time to substantially dry but not to substantially cure the composition, and then heated for a second time at a higher temperature and / or for a longer period of time to effect the curing. Said process, referred to as "of step B", can be used to provide nonwoven material treated with binder, for example, in roll form, which can be cured in a subsequent step, with or without forming or molding in a configuration particular, concurrent to the curing process. The heat-resistant non-woven material can be used for applications such as, for example, cotton sheets or insulation rolls, as reinforcement material for floor or ceiling applications, as a wick, as a substrate with micro-glass base for boards of printed circuit or battery separators, as filter material, tape material and as reinforcing cotton fabric in coatings that are cement or not, for masonry. The following examples are intended to illustrate the formaldehyde-free curable aqueous composition, and the use thereof as a binder for heat resistant nonwoven material.

Example 1: Preparation of fiberglass paper for hands, and saturation of paper sheets with binder composition. A 110 gallon (416.4 liters) tank equipped with an air driven mixer was filled with deionized water. The pH of the water was adjusted to 9.0 with ammonium hydroxide. Fourteen ppm of Rhodameen VP-532 (Rhone Poulenc) [a polyoxyethylated alkyl amine] and 31 ppm of Magnifloc 1885A (Cytec Industries) [a polyacrylamide], based on the weight of the water, were added to the water. The solution was stirred for 15 minutes and then allowed to stand for 15 minutes. This water is known as "white water". Five gallons of white water was pumped into a six-gallon stainless steel dispersion tank, equipped with an air-handled mixer and four vertical deflectors to provide more complete mixing. The agitator was turned on and 2.5 grams of glass fibers with a length of W (6.25 mm) were added. This formed a fiberglass dispersion. The glass fiber dispersion was then mixed for three minutes. A polyester cotton fabric was placed at the bottom of a Williams sheet mold of twelve by twelve inches (30 cm x 30 cm) square. The mold was closed and filled in half with water. The agitator in the dispersion tank was turned off. After 30 seconds, the valve in the dispersion tank was opened to drain the glass fiber dispersion in the sheet mold. Simultaneously, the drain valve in the sheet mold was opened, allowing the fibers to form the sheet in the cotton fabric. The sheet mold was opened and the cotton fabric with the fiberglass sheet formed was lifted and transferred to a screen support. The excess water was removed by vacuum with a dry / wet vacuum cleaning device that was adjusted with a head, 14 inches (35 cm.). The binder composition was applied with a perforated hopper, maintaining a light flow so that the fibers were not agitated. The excess binder composition was removed by vacuum. After a tour was made, the sheet was turned 90 degrees and another tour was made. This is called a treated fiberglass sheet. The fiberglass sheet treated immediately was transferred to another piece of screen to prevent sticking to the first screen. The fiberglass sheet was then dried and cured for three minutes at 190 ° C in a high-volume Werner-Mathis oven. The target loss in ignition was 22% and 0.5 lb./lOO square feet (25 gr./m2) in basis weight.

Example 2: Preparation of the binder composition with 5% dicidiamide. To 32.82 grams of polyacrylic acid (Mw = 9,000) [Polyacid A] and 59.08 grams of polyacrylic acid (60,000 Mw) [Polyacid B] were added 5.4 grams of triethanolamine (TEA), 1.87 grams of dicyandiamide (dici), 18.33 grams (1.0%) of Dow Corning silane [optional, depending on the fiberglass used] and 165.94 grams of water. This mixture contains 13.0% of active ingredients (all components except water) with a pH of approximately 3.0 and 10 cps viscosity (Brookfield LVF, axis # 1 at 60 rpm). The binder was applied as described in example 1.

Examples 3 to 8: Preparation of binder compositions with other levels of diacyanamide. Binder compositions with other levels of dicyandiamide, including a system without dicyandiamide for comparison, were prepared according to the ingredient levels shown in Table 1, which include dicyandiamide levels of 0, 2, 4, 6, 8 and 10% (examples 3, 4, 5, 6, 7 and 8, respectively). With up to 10% dicyandiamide, solubility becomes a limiting factor. Examples 2 through 8 were tested for dry and wet tensile strength, as follows: the cured sheet was cut by 1 inch (2.5 cm.) By four inches (10 mm). cm.). The test specimens were tested for dry tensile strength by placing them in the jaws of a Thwing-Albert Intelect tensile tester. The samples were separated at a crosshead speed of 2 inches (5 cm.) / Minute. The wet tensile strength was measured by soaking a second set of cured and prepared specimens identically. The samples were soaked in water at 85 ° C for one hour. The samples were removed from the water and immediately tested for tensile strength while still wet. The percent retention, wet tensile strength / dry tensile strength x 100, is then calculated. Because there is variability in the preparation of sheets of paper for hands, the percent retention is particularly significant when evaluating the extent of strength development, as regards the degree of interlacing. Another desirable property is the hot tensile strength, which is required for some operations. For this, the test specimens were tested to verify the tensile strength with an Instron tensile tester fitted with a heating chamber. The specimens were tested at 193 ° C. Percent retention, hot tensile strength / dry tensile strength (room temperature) x 100, was also determined. Typical test results are shown in Table 2.

Table 1 Example Grams Grams Grams Grams Grams Z- Grams Polyacid A polyacid B TEA dici 6040 (1.0%) water 3 32. 82 59. 08 5. 4 0 17. 86 147. 91 4 32. 82 59. 08 5. 4 0. 71 17. 36 153. 02 5 32.52 59.08 5.4 1.45 18.13 163.38 6 32.52 59.08 5.4 2.27 18.53 168.37 7 32.52 59.08 5.4 3.09 18.93 173.36 8 32.52 59.08 5.4 3.95 19.35 178.60 Table 2% Tensile strength, N / 5 cm. Retention percent Example dici dry hot humid hot hot 2 5 103 35 57 34.0 55.-3 3 0 113 9 74 8.0 65.5 4 2 102 10 60 9.8 58.8 4 112 27 77 24.1 68.8 6 6 102 39 61 38.2 59.8 7 8 99 40 54 40.4 54.5 8 10 122 55 65 45.1 53.3 These examples show that increasing the level of dici increases moisture retention.

Examples 9 to 13: Effect of an accelerator with dicyandiamide. The addition of an accelerator, such as sodium hypophosphite or sodium tetrafluoroborate, improves development. Table 3 shows various variations of dici / accelerator. Each example uses 32.82 grams of Polyacid A and 59.08 grams of Polyacid B, 5.4 grams of triethanolamine, 0.5 available in Dow Corning% Z-6040 (3-glycidoxypropyltrimethoxysilane) (based on the total active components) and water to give a final solid of -13.0%. The dici and accelerator levels are shown in table 3.

Table 3 -SHP = sodium hypophosphite -TFB = tetrafluoroborate Example dici, grams type of accelerator, grams (%) * accelerator (%) * / ** 9 0 (0) SHP 1.08 (2.5) 10 1.87 (5.0) SHP 0.54 (1.25) 11 1.87 (5.0) TFB 0.46 (1.25) ) 12 1.87 (5.0) SHP 0.27 (0.61) 13 1.87 (5.0) TFB 0.23 (0.61) *% of total active components ** differences in SHP / TFB levels due to the different purity. The typical test results of these systems are shown in table 4.

Table 4 Traction resistance, N / 5 cm. % retention E ample Accelerator (%) dry humid hot hot hot 9 SHP (2.5) 96 46 50 47.9 59.4 10 SHP (1.25) 90 65 66 72.2 73.3 11 TFB (1.25) 100 72 69 72.0 69.0 12 SHP (0.61) 84 25 58 29.8 69.0 13 TFB (0.61) 99 66 62 66.6 62.6 Examples 14 to 17: Effect of cure temperature on the development. The previous examples were cured at 190 ° C. The following examples were cured for three minutes at 180 ° C .. Example 14: repetition of example 2 with 180 ° C cure. Example 15: repetition of example 8 with 180 ° C cure. Example 16: repetition of example 11 with 180 ° C cure. Example 17: repetition of example 13 with 180 ° C cure. The test data is shown for these examples in Table 5.

Table 5 Tensile strength, N / 5 cm. Example% dici accelerator (%) dry wet% retention 14 5.0 0 (0) 106 4 3.8 15 10.0 0 (0) 108 18 16.7 16 5.0 TFB (1.25%) 103 34 33.0 17 5.0 TFB (0.61) 94 35 37.2 This data shows that even lower levels of accelerator help maintain a high level of retention, compared to the dici by itself even at a high level.

Example 18: Effect of the different polyol. A binder with a different polyol, trimethylolpropane, was prepared as follows: 32.82 grams of Polyacid A, 59.08 grams of polyacid B, 4.91 grams of trimethylolpropane, 1.87 grams of dicyandiamide, 0.55 grams of TFB, 17.87 grams of Z-6040 (1.0% ) and 219.65 grams of water were mixed and used to prepare a sheet as described in example 1. The final sheet had a 67 N / 5 cm. of dry traction, 38 N / 5 cm. of wet tensile strength for a retention of 56.7%. This shows that a useful balance of properties with different types of polyols can be achieved.

Example 19: Comparison with triazinetrione A triazinetrione [1,3,5-tris (2-hydroxyethyl) cyanuric acid] (THEIC) (one of the preferred compounds in EP-B-0672720) was evaluated on a glass fiber other than the one used in the previous examples. This was a one-inch (2.5 cm) fiberglass and was prepared at a nominal BW = 1.61b. / sq. (78 gr./m2) and LOI = 22%. The binders were prepared as follows: Table 6 Example Polyacid TEA THEIC SHP PTSA water A 19 78.28 11.0 2.22 164.32 78.28 19.36 - 202.36 21 78.28 19.36 1.08 208.39 The leaves were prepared as in Example 1. They were cured for three minutes at 190 ° C. The THEIC system was also cured for three minutes at 220 ° C. The data of the test are shown in table 7: Table 7 Traction resistance, N / 5 cm. Example Temp. of cure, ° C dry moist% retention 19 190 262 160 61.0 20 190 223 8 3.6 20 220 214 105 49.1 21 190 232 48 20.7 • The results show low retention percentage of the THEIC system when cured at 190 ° C but good retention percentage when cured at 220 ° C. As a comparison, the results obtained in previous examples indicate that a good retention percentage can be achieved with the dici systems at 190 ° C and the dici / accelerator systems at 180 ° C ..

Claims (8)

1. Claims 1. A formaldehyde-free curable composition, comprising: (a) a polyacid comprising at least two carboxylic acid groups, anhydride groups or polyacid salts thereof; (b) an active hydrogen compound containing at least two active hydrogen groups selected from the group consisting of hydroxyl, primary amino, secondary amino and mixtures thereof; and (c) one or more compounds selected from the group consisting of cyanamide, dicyandiamide, 1,2-mono- or di- (Cx-Cg alkyl) substituted-3-cyanoguanidines such as ethyl-3-cyanoguanidine, 1-2. diethyl-3-cyanoguanidine and 1,2-diisopropyl-3-cyanoguanidine, and 1,2-mono- or di- (C6-C1-aryl) substituted -3-cyanoguanidines, such as phenyl-dicyandiamide; and, optionally (d) an accelerator; wherein the scale of the number of equivalents of said carboxylic acid groups, anhydride groups or salts thereof to the number of equivalents of said active hydrogen groups is from 1 / 0.01 to about 1/3, and wherein said carboxylic acid groups, Anhydride groups or salts thereof are neutralized to a point of less than 35% by weight with a fixed base.
2. 2. A composition according to claim 1, wherein the component (c) is cyanamide and / or dicyandiamide.
3. 3. A composition according to claim 1 or 2, wherein the accelerator is a phosphorous compound and / or fluoroborate compound.
4. 4. A composition according to any of the preceding claims, wherein the composition is an aqueous composition.
5. 5. A composition according to any of claims 1 to 3, wherein the composition is in the form of dry powder or granules.
6. 6. A composition according to any of the preceding claims, wherein the composition comprises component (c) in an amount of 3 to 8% by weight, based on the weight of components (a), (b) and ( c) A composition according to any of the preceding claims, wherein the composition comprises component (d) in an amount of about 0.01 to 10% by weight, based on the weight of components (a), (b) and (c). 8. A method for bonding heat-resistant fibers of a non-woven material, comprising: (I) contacting said fibers with a formaldehyde-free curable composition, as claimed in each of the preceding claims; and subsequently (II) heating the formaldehyde-free curable composition and the fibers at an elevated temperature, preferably from 120 ° C to 300 ° C, and more preferably less than 200 ° C, for a sufficient time to effect the cure. SUMMARY OF THE INVENTION A formaldehyde-free curable composition useful for binding non-woven material, comprising: (a) a polyacid comprising at least two carboxylic acid groups, anhydride groups or the polyacid salts thereof; (b) an active hydrogen compound containing at least two active hydrogen groups selected from the group consisting of hydroxyl, primary amino, secondary amino and mixtures thereof; and (c) one or more compounds selected from the group consisting of cyanamide, dicyandiamide, 1,2-mono- or di- (C 1 -C 6 alkyl) substituted-3-cyanoguanidines such as ethyl-3-cyanoguanidine, 1,2 -diethyl-3-cyanoguanidine and 1,2-diisopropyl-3-cyanoguanide, and 1,2-mono- or di- (Cß-C? 2 aryl) substituted-3-cyanoguanidines, such as phenyl-dicyandiamide; and optionally (d) an accelerator; wherein the scale of the number of equivalents of said carboxylic acid groups, anhydride groups and salts thereof to the number of equivalents of said active hydrogen groups is from 1 / 0.01 to 1/3, and wherein said carboxylic acid groups, anhydride groups or salts thereof are neutralized to a point of less than 35% by weight with a fixed base. The accelerator can be a phosphorous and / or fluoroborate compound. The compositions allow to manufacture with flexibility through lower curing temperatures.