NO832545L - POLYMER COMPOSITION - Google Patents

Description

The present invention relates to a stable aqueous polymer mixture and the distinctive feature of the polymer mixture according to the invention is that it comprises:

Sn anionic polyurethane dispersion, and

one compatible (miscible) polymer dispersion or emulsion in which the polymer is water insoluble.

These and other features of the invention appear in the patent claims.

The invention is particularly relevant in connection with the production of resin-impregnated fibrous webs with a completely uniform density and which can be further processed into simulated web-like web materials.

Resin-impregnated: porous sheet materials such as textile cloth, felted materials and water-deposited materials and the like are well known. These resin-impregnated sheet materials are useful for a variety of purposes, including artificial leather in the form of vinyl materials and similar structural sheet materials such as conveyor belts and similar products.

Previous methods of impregnating a particular web include impregnating or coating a porous material with a polymeric resin such as a polyurethane, vinyl or a similar material. Polyurethanes have proven very beneficial as a coating or impregnation composition due to their ability to be widely varied in terms of chemical and physical properties, especially their flexibility and chemical resistance. When impregnating the porous sheet material with a polymer resin, different methods are used. Such an earlier method involves the use of the polymeric resin in an organic release agent system in which the sheet material is immersed in the solution and the solvent is removed therefrom. These solvent systems are undesirable because the solvent is in many cases toxic and must either be recovered for renewed use or disposed of. These solvent systems are expensive and do not necessarily give a desired product as the solvent, when evaporated from the impregnated porous sheet material, will cause the resin to often migrate to cause a non-homogeneous impregnation of the porous sheet material and this leads to resin richness towards the surface of the sheet material and not a uniform impregnation. To remedy the problems with solvent systems, certain aqueous polymeric systems have been proposed. When producing impregnated sheet materials by impregnation with aqueous polymers, the aqueous portion must be removed. Here, too, heat is required and migration of the polymer to the surfaces of the impregnated sheet material is encountered.

In a method for combining polyurethane solutions with porous substrates, the polymer is applied in an organic solvent to a substrate such as e.g. a needle. Nice polyester felt. The polymer-substrate composition is then bathed with a mixture of organic solvent for the polymer and a non-solvent for the polymer which is at least partially miscible with the solvent until the layer is coagulated into a cellular structure of interconnected micropores. The solvent is removed from the coating layer together with the solvent to produce a solvent-free <:>microporous layer. Although this process provides usable properties for a polyurethane-impregnated textile, it still has the disadvantage of an organic solvent system, especially when high-grade polyurethanes are used which require relatively toxic and high-boiling solvents. An example of this method is discussed in US patent 3,208,875.

In another method, polyurethane dispersions have been proposed

in organic carriers used for coating porous substrates, e.g. as discussed in US Patent 3,100,721.

In this system, a dispersion is applied to a substrate and coagulated by further addition of a non-solvent. Although this method has been used with some success, it entails two significant limitations: (1) the carrier in the dispersion is mainly organic as relatively small amounts of a non-solvent, preferably water, are needed to form a dispersion, and (2) the is a narrow usable range for the addition of non-solvent so that it is difficult to achieve reproducible results.

A particularly useful method for producing composite sheet material by impregnating a porous substrate is discussed in US patent 4,171,391. In this system, a porous sheet material is impregnated with an aqueous ionic dispersion of a polyurethane and the impregnating agent is coagulated therein.

Another method of forming impregnated porous substrates, and in particular non-woven sheet materials, involves impregnating fibrous needle filters by fully saturating the felt with an aqueous dispersion or emulsion of a polymeric resin. The fully saturated needle felt is brought into contact with a coagulant to coagulate the polymer resin from the aqueous dispersion and deposit the polymer resin in the needle felt. The felt is dried to form an impregnated fibrous web with polymer resin distributed in the felt, with a completely uniform web density, and the bulk density of the web is less than the actual density of the web. The impregnated web is characterized by having filaments that are both coated and uncoated with polymer resin and concentrations of polymer ((resin .

A particular application for the proposed sheet material is the formation of leather-like materials from it, by heating the impregnated fibrous mass under pressure and temperature where pressure and temperature are applied to at least one surface - of the material to develop a scar layer on one surface and a gap layer on the opposite surface so that a leather-like sheet material is formed. In these methods and also according to US Patent 4,171,391, the preferred polymers are polyurethanes because of their superior physical and chemical properties. The present invention is an improvement over these impregnation methods in that it uses additional polymers as impregnation mixtures and these additional polymers provide improved properties and also allow variations in properties for particular end uses.

The stable aqueous polymer blisters according to the invention consist of an aqueous anionic polyurethane dispersion and a compatible (miscible) polymer dispersion or emulsion.

The compatible dispersions or emulsions have a substantially neutral pH or are anionic or cationic. The polymer mixtures are useful for impregnating porous substrates to form composite sheet materials which can be further processed to form artificial leather and the like.

The aqueous ionic polyurethane dispersion component in the impregnation blueriding is anionic and preferably has carboxylic acid groups covalently bound to the main polymer chain.

Neutralization of these carboxyl groups with an amine, preferably a water-soluble monoamine, gives water dilutability. Careful selection of the compound carrying the carboxyl group must be made because isocyanates, which are necessary components in every polyurethane system, are generally reactive with carboxyl groups. As discussed in US patent 3,412,054, however, 2,2-hydroxymethyl-substituted carboxylic acids can be reacted with organic polyisocyanates without significant reaction between the acid and isocyanate groups. due to the steric hindrance of the carboxyl groups by the neighboring alkyl groups. This method gives the desired carboxyl-containing polymer where the carboxyl groups are neutralized with the tertiary monoamine to give an internal quaternary ammonium salt and consequently water dilutability.

Suitable carboxylic acids, and preferably the sterically hindered carboxylic acids, are well known and readily available. They can e.g. is prepared from an aldehyde containing at least two hydrogen atoms in the alpha position which is reacted in the presence of a base with two equivalents of formaldehyde to give 2,2-hydroxymethyl aldehyde-. This aldehyde is then oxidized to the acid using methods that are well known to those skilled in the art. Such acids are represented by the structural formula.

in which R stands for hydrogen, alkyl with up to 20 carbon atoms and preferably up to 8 carbon atoms. A preferred acid is 2,2-dihydroxymethyl propionic acid. The polymers with the attached carboxyl groups are characterized as anionic polyurethane polymers.

The polyurethanes used in the execution of the invention in particular entail the reaction between di- or polyisocyanates bg compounds with several reactive hydrogen atoms suitable for the production of polyurethanes. Such diisocyanates and reactive hydrogen compounds are more fully discussed in US Patents 3,412,034 and 4,046,729.

The method for producing these polyurethanes is discussed in detail and exemplified in the aforementioned patents. In accordance with the present invention, aromatic, aliphatic and cycloaliphatic isocyanates or mixtures thereof can be used to produce the polymer. These isocyanates are e.g. tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, meta-phenylene diisocyanate, biphenylene-4-; 4 1-diisocyanate, methylene-bis-4-phenyl isocyanate, 4-chloro-1,3-phenylene diisocyanate, naphthylene-145-diisocyanate, tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate, decamethylene-1 ,10-diisocyanate, cyclohexylene-1,4-diisocyanate, methylene-bis-4-cyclohexyl isocyanate, tetrahydronaphthylene diisocyanate, isophorone diisocyanate and the like. Preference is given to using arylene and cycloaliphatic diisocyanates with the greatest advantage

in the practice of the invention.

Characteristically, the arylene diisocyanates include those in which the isocyanate group is attached to the aromatic ring. The most preferred diisocyanates are the 2,4- and 2,6-isomers of toluene diisocyanate and mixtures thereof, because of their ready availability and their reactivity. Furthermore, the cycloaliphatic diisocyanates which are most advantageously used in the practice of the invention are 4,4'-methylene-bis-cyclohexyl isocyanate and isophorone diisocyanate.

Selection of the aromatic or aliphatic diisocyanates is dictated by the end use of the particular material. As is well known by the person skilled in the art. area, the aromatic diisocyanates can be used where the end product is not too strongly exposed to ultraviolet radiation, which will tend to give such polymer mixtures a yellow colour, while the aliphatic diisocyanates can be more advantageously used for outdoor applications where they have less of a tendency to become yellowed by exposure to ultraviolet radiation. Although these principles form a general basis for the selection of the particular isocyanate to be used, the aromatic diisocyanates can be further stabilized using well-known ultraviolet stabilizers to improve the final properties of the polyurethane-impregnated sheet material. In addition, antioxidants can be added in amounts well known to the person skilled in the art to improve the properties of the final product. T i Typical antioxidants are the thioethers and the phenolic antioxidants such as 4,4<1->butylidine-bis-metalcresol and 2,6-di-tertbutyl-paracresol.

The isocyanate is reacted with the multiple reactive hydrogen compounds. bonds such as diols, diamines or thirioles. In the case of diols or triols, they are typically either polyalkylene ether or polyester polyols. A polyalkylene ether polyol is the preferred active hydrogen-containing polymer material for the composition of the polyurethane. The most useful polyglycols have a molecular weight of 50 to 10,000 and in the context of the invention, the molecular weight is preferred from about 400

to 7000. Furthermore, the polyether polyols improve flexibility-. a proportional to the increase in their molecular weight.

Examples of polyether polyols are polyethylene ether glycol, polypropylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyoctameylene ether glycol, polydecamethylene ether glycol, polydodecamethylene ether glycol and mixtures thereof. Polyglycols containing several different radicals in the molecular chain such as; e.g. the compound HO(CH_OC,H .0) H in which n is an integer greater than 1, can

2 2 4 n'

also used.

The polyol can be a hydroxy-terminated or hydroxy-substituted polyester which can be used instead of or in combination with the polyalkylene ether glycols. Examples of such polyesters are those formed by reacting acids, esters or acid halides with glycols. Suitable glycols are polymethylene glycols such as ethylene, propylene, tetramethylene or decamethylene glycol, substituted methylene glycols such as 2,2-dimethyl-1,3-propanediol, cyclic glycols such as cyclohexanediol and aromatic glycols. Aliphatic glycols are generally preferred when flexibility is desired. These glycols are reacted with aliphatic, cycloaliphatic or aromatic dicarboxylic acids or lower alkyl esters or ester-forming derivatives to produce relatively low molecular weight polymers, preferably with a melting point below about 70°C and a molecular weight similar to those indicated for the polyalkylene ether glycols. Acids for the production of such polyesters are e.g. phthalic acid, maleic acid, rapsic acid, adipic acid, coric acid, sepacic acid, tetraphthalic acid, and hexahydrophthalic acid and alkyl- and halogen-substituted derivatives of these acids. In addition, polycaprolactone terminated with hydroxyl groups can also be used.

By the term "ionic dispersant" used herein is meant an ionizable acid or base which can form a salt with the solubilizing agent. These "ionic dispersants" are amines and preferably water-soluble amines such as triethylamine, tripropylamine, N-ethyl piperidine and the like. Acids and preferably water-soluble acids such as acetic acid, propionic acid, lactic acid and the like can also be used. Of course, the acid or amine will be selected in accordance with the solubilizing group substituted on the polymer chain.

The desired elastomeric character will generally require about 25 to 80% by weight of a long chain polyol (equivalent weight 700 to 2000) in the polymer. The properties with regard to elongation and elasticity can vary greatly from product to product depending on the desired properties in the final product.

When forming the polyurethanes useful in carrying out the invention, the polyol and a molar excess of diisocyanate are reacted to form isocyanate-terminated polymer. Although suitable reaction conditions and reaction times and temperatures can be varied within the framework of the particular isocyanate and the particular polyol used, the person skilled in the field will easily determine these variations. The person skilled in the art will know that the reactivity of the components used requires a balance between reaction speed and unwanted secondary reactions that lead to coloring and molecular weight deterioration. Typically, the reaction is conducted with stirring at about 50 to about 120°C for about 1 to about 4 hours. To provide substituting carboxyl groups, the isocyanate-terminated polymer is reacted with a molar deficit of dihydroxy acid for 1 to 4 hours at 50 to 120°C to form the isocyanate-terminated prepolymer. The acid is preferably added as a solution in e.g. N-methyl-1,2-pyrrolidone or N-N-dimethylformamide. The solvent for the acid will typically not make up more than about 5% of the total mixture in order to reduce the concentration of the organic solvent in the polyurethane mixture. After the dihydroxy acid has reacted into the polymer chain, the substituting carboxyl groups are neutralized with an amine at about 58 to 75°C for about 20 minutes and chain extension and dispersion is accomplished by addition to water with stirring. A water-soluble diamine can be added to the water as a further chain extender;'. The chain extension involves reaction of the remaining isocyanate groups with water to form urea groups and further polymerize the polymer material with the result that all the isocyanate groups are reacted by means of the addition of a large stoichiometric surplus of water. It should be noted that the polyurethanes used in the invention are thermoplastic in nature, i.e.

that they are not capable of particularly strong further hardening after formation, except with the addition of an additional hardening agent.

Sufficient water is used to disperse the polyurethane at a concentration of about 10 to 40% solids by weight and a dispersion viscosity in the range of 10 to 1000 centipoise. The viscosity can be set in accordance with the special desired properties and the special dispersion composition, all of which are dictated by the final product properties. is. It should be noted that no emulsifiers or thickeners are necessary for the dispersion's stability.

The person skilled in the art will readily modify the primary polyurethane dispersion in accordance with the use of the final product, e.g. by adding dyes, compatible vinyl polymer dispersions, ultraviolet filtering compounds, oxidation stabilizers and the like.

The characterization of the dispersions produced in accordance with the invention is done by measurements of the content of non-volatile components, particle size, viscosity measurements and

when measuring tensile/stress properties on strips of cast film.

It has been found that the anionic polyurethane dispersions form a coagulation matrix and while compatible polymer dispersions or emulsions can be mixed to form homogeneous stable aqueous mixtures, the addition of anion to the mixture will cause the entire polymer system to instantly coagulate to form a coagulate of homogeneously blended polyurethane polymer and the other polymer.

The polymer dispersions or emulsions useful in the practice of the invention are anionic, cationic or nonionic dispersions or emulsions of polymers which are water insoluble in their coagulated state and are compatible with the anionic polyurethane dispersion.

The polymers in these dispersions or emulsions can be elastomeric polymers such as neoprene, polyvinyl chloride, polyacrylate polymers, polyolefin polymers, polyfluoroolefin polymers and the like.

It is understood that, in accordance with the invention, significant amounts of the polymer other than the polyurethane polymer can be incorporated into the aqueous mixture.

Neoprene latexes usable in the practice of the invention

are those which are non-ionic, i.e. is emulsified with a nonionic emulsifier and has a pH of about 7. This is in contrast to the commercial anionic and cationic neoprenes which are not useful in the practice of the present invention. The anionically emulsified neoprene latexes available in the trade are not compatible with the aqueous anionic polyurethane dispersion so that when the two are mixed together they will coagulate or precipitate so that they cannot be used as impregnation mixtures.

On the other hand, the nonionic neoprene latexes are compatible with the aqueous anionic polyurethane dispersions to form stable aqueous polymeric compositions. Surprisingly, these nonionic neoprene latexes will coagulate under ionic conditions only when combined with the polyurethane dispersion to provide a coagulate composed of neoprene polymer and polyurethane polymer. Surprisingly, essentially all nonionic neoprene coagulates with the anionic polyurethane dispersion.

Polyvinyl chloride resins which are formed by polymerization of vinyl chloride and which may include vinylidene chloride to

raise the glass transition temperature.can be incorporated as anionic particle dispersions. The polyvinyl chloride dispersions are known to be extremely stable due to their fine particle size, i.e. approximately 0.2 micrometers and does not coagulate when acidified to the level usually used for the coagulation of polyurethane dispersions.

In addition to the polyvinyl chloride resin dispersions and neoprene latexes, aqueous polymer dispersions such as polyacrylate and polytetrafluoroethylene can be used as long as the polymeric dispersions are compatible with the polyurethane dispersion to form a stable aqueous resin mixture.

Up to 65% by weight of the polymer other than the polyurethane polymer on a solids basis may be used in the mixture to achieve complete coagulation of the polyurethane and the other polymer to form a homogeneous coagulate. More than 65% by weight of the polymer other than the polyurethane polymer, the entire amount of this polymer will not coagulate and some will remain in the aqueous phase.

At least 30% by weight of the other polymer than the polyurethane polymer on a dry matter basis is necessary to significantly modify the properties of the final product.

More particularly, the viscosity of the anionic polyurethane dispersion and aqueous polymer dispersion or emulsion forming the stable aqueous mixture should be at a level of about 10 to 5000 centipoise to provide complete penetration of the aqueous system into the porous sheet material.

The polyurethane polymer and the other polymer should be impregnated into the porous sheet material and especially the fibrous filter in an amount of at least: 70% by weight addition based on the weight of the fibrous felt and up to 400% by weight. Preferably, the resin is impregnated in an amount of about 200 to 300% by weight addition based on the weight of the porous sheet material. Coagulation is carried out by bringing the impregnated substrate into contact with the aqueous solution of an ionic medium for ionic replacement of the solubilizing ion. Theoretically, although one does not wish to be bound by any such theory, in the case of anionic solubilized polymer, the amine that neutralizes the carboxyl-containing polyurethane is replaced by a hydrogen ion that brings back the anionic carboxyl ion so that the polymer is returned to its original - non-dilutable state. This causes coagulation of the polymer inside the substrate. The stable aqueous polymer mixture can be coagulated with aqueous acidic acid solutions having co-concentrations of 0.5% to about 75%. Furthermore, the stable aqueous polymer mixture can be coagulated by the addition of sodium or potassium silicofluoride as described in US Patent 4,332,710.

When impregnating the felt with the stable aqueous polymer mixture, the felt is immersed therein with a concentration sufficient to provide a deposit of at least 70% by weight of dry matter. After initial immersion of the felt in the aqueous emulsion or dispersion, the felt may be pressed to remove air and resaturated by means of another immersion in the stable aqueous polymer mixture to provide full impregnation of the aqueous polymeric system within the felt. The felt, which is completely impregnated with the aqueous mixture, is passed through wiping rollers or the like to remove excess dispersion and/or emulsion on the surface of the impregnated felt. The felt is then immersed in a bath containing a counterion, or heated if the aqueous polymer mixture contains a silicofluoride to provide coagulation of the resin within the fibrous structure. It is noted that the coagulation is instantaneous and that the coagulate is fixed inside the felt. After drying, the polymer does not migrate. After coagulation, the felt can be pressed to remove excess water and dried to form the impregnated web. The stable aqueous polymer mixture can also be used in the process described in US Patent 4,171,391 to provide special products.

When complete impregnation is achieved, the felt is completely saturated, i.e. without any remaining air spaces, with the stable aqueous polymer mixture providing a maximum addition of at least 70% by weight polymer resin based on the weight of the felt. After drying, the felt has a new structure in which the felt throughout has a uniform density and the bulk density of the web is less than the current density of the web. Photomicrographs of this structure show both coated and uncoated filaments and concentrations of resin, along with voids. While the bulk density is essentially uniform throughout the thickness of the material, the structure is homogeneous on a microscopic scale.

A completely impregnated felt can e.g. be handled in the following manner.

The complete impregnated web or felt is placed in a press and pressure and heat are applied to both sides thereof. Pressure and temperature are sufficient to fuse the polymer inside the impregnating agent at the surface of the material but still insufficient to completely fuse the polymer in the interior of the sheet material. This process develops a density gradient from the interior of the nonwoven sheet material to the exterior. The thickness of the heated and pressed sheet material can be regulated by the pressure exerted during the operation of heating and pressing, or by inserting spacers between the test plates, or by using a press with so-called final load. In another process for forming artificial leather material from the non-ionic neoprene latex and aqueous polyurethane dispersion which constitutes the coagulated material inside the fibrous felt, this can be placed in one press with only one of the surfaces heated to form the grain layer while the opposite side on the cold surface forms the gap layer. The characteristic features of the artificial leather sheet material are primarily physical features in which a density gradient is provided from one side of the sheet material to the opposite side of the sheet material. Preferably, the density gradient is uniform. A surface of the impregnated fibrous mass delimits a grain layer and this grain layer has a current density corresponding to its bulk density.

/^Bulk density" as used herein means to refer to the density of the material inclusive of air spaces. "Actual density" as used herein means to refer to the density of the material without air spaces, i.e. specific gravity.

This grain layer simulates very closely the grain layer in natural leather. On the opposite side of the sheet material, there is a surface that delimits the gap layer which is a bulk density less than its actual density, as there is a preferred even density gradient through the material. The split layer is somewhat fibrous and simulates the split layer in natural leather.

EXAMPLE 1

In a suitable container, 100 parts by weight on a dry matter basis of an aqueous anionic cross-linked polyurethane dispersion are introduced at a dry matter content of 25%. The polyurethane coating is as described in example 1 in US patent 4,171,391. To the polyurethane dispersion is added 100 parts by weight of fused silica sold under the designation "Imsil 15" manufactured by Illinois Mineral Co., together with 100 parts by weight on a dry matter basis of ^neoprene latex sold by E.I. Du Pont de Nemours Company as "Neoprene Latex 115" which is a copolymer of chloroprene and methacrylic acid with polyvinyl alcohol as dispersant. The pH in the neoprene was approximately 7 and the dry matter content 47% by weight. The final pH of the mixture of neoprene latex, anionic polyurethane dispersion and silica was 75 to 8.0. To this mixture was added 0.6% by weight; sodium silicofluoride based on the weight of the mixture and 0.3% borax as a buffer. After the impregnation mixture was prepared, it was applied to an approximately 500 v/m 2 polyester fiber felt with 12 denier per filament. The pad was completely saturated with the stable aqueous polymer mixture by immersing the felt in the mixture for 15 seconds. The felt took up 600% of the aqueous system. Coagulation was carried out by immersing the completely saturated felt in the water bath at 93°C and resulted in complete coagulation of the neoprene and polyurethane inside the felt. The immersion water was clear and this showed that the main amount, or the entire amount, of the resin remained coagulated in the felt. The impregnated felt was dried using a radiant heat device and had 125% by weight of downprene, polyurethane and silicon dioxide and a thickness of approximately 6.35mm: with a bulk density of 0.5g/cc. The dried composition was compressed at 190°C under pressure to a density of 1.2.

The final synthetic leather sheet material had a soft pliable structure suitable for conveyor belts, regular belts and similar leather products.

EXAMPLE 2

Example 1 was repeated with the exception that the polyurethane dispersion used was the one described in US Patent 4,171,391 in Example 2 and required 1.0% sodium silicofluoride and 1.2% borax; After treatment under pressure and heat, the product had a firm texture suitable for conveyor belts and ordinary belts.

EXAMPLE 3

Into a suitable container were introduced 100 parts by weight of a vinyl chloride/vinylidene hybrid copolymer aqueous anionic dispersion and 100 parts by weight of an anionic aqueous polyurethane dispersion. The vinyl chloride copolymer is sold under the trade name "Geon 460X" by the B.F. Goodrich Company and had a TWA of 50°C and consist of 46% dry matter.- Polyurethane dispersion<n>had 325% dry matter f and was prepared in accordance with exchange example 1 in US patent document 4,171,391. Total solids content of the final mixture was 38% in water. The mixing led to a stable aqueous mixture. 13.8% by weight of sodium silicofluoride based on the weight of the mixture was added to it with stirring. The aqueous mixture was used to impregnate a 100% polyester fiber felt with 10 denier/filament and a bulk density of approximately 500 g/m 2 . The felt was saturated by immersion in the aqueous mixture for 15 seconds to achieve full impregnation. The weight increase of the felt was 600%. The aqueous mixture was coagulated by immersing the impregnated felt in a water bath at 93°C. Coagulation was instantaneous upon application of heat. The coagulation water was clear and this showed that the coagulation was complete and that all the vinyl chloride polymer was back in the coagulate. The impregnated felt was dried using a radiant heat device and had a dry weight gain of 220% polymer.

The dried assembly was approximately 6'.35 mm thick with a density of 0.6 g/cm 3 . The assembly was in the form of a rigid plate. The composition was pressed to a density of 1.2 at 135°C. The hot-pressed assembly was extremely flexible and could be molded to a contoured shape. On cooling to room temperature, the assembly became rigid with a glistening surface. This can be placed in a mold, heated and shaped to give car parts, unbreakable sports equipment and the like.

EXAMPLE 4

A homogeneous mixture with 46% total solids was prepared by mixing 40 parts by weight of 60% solids polytetrafluoroethylene latex with 35 parts by weight of a 30% solids polyurethane dispersion. The aqueous polytetrafluoroethylene latex was stabilized with a nonionic surfactant sold under the designation "Teflon 30" by E.: I. Du Pont Nemours Company. The polyurethane dispersion was in accordance with Example

1 herein. A weight % of sodium silicofluoride based on the weight of the homogeneous mixture was added. After heating to approximately 54 C, the mixture coagulated with mainly full-

dig coagulation?.of the polymers-7deri ~and formed a stiff gel.

The leather-like sheet materials produced by means of the invention, together with the impregnated products, differ from correspondingly impregnated only with the polyurethane dispersion in that they can be built up to have higher viriv strengths or greater or less flexibility and can be made capable of being designed to form aesthetically appealing surfaces at lower temperatures than equivalent polyurethane dispersions while maintaining their physical properties. A wider product range can thus be provided with the help of the invention.

Claims (10)

1. Stable aqueous polymer dispersion, !:~ characterized in that it comprises: an anionic polyurethane dispersion, and a compatible (miscible) polymer dispersion or emulsion in which the polymer is water insoluble. 2. Procedure for producing a composite sheet material, - characterized by: a fibrous web is impregnated with an aqueous ionic dispersion of a polyurethane polymer:; and a compatible (miscible) -, ::.■' <-,-/-•[ < anionic, cationic or nonionic dispersion or emulsion of a polymer selected from the group consisting of neoprene,'polyvinyl chloride, poly acrylate polymers, polyolefin polymers and polyfluoroolefin polymers in which the polymer is water soluble in its coagulated state, polyurethane and compatible dispersion or emulsion is ionically coagulated to form an impregnating agent in which the polymer other than the polyurethane polymer is present in an amount of 30 to 65% by weight based on the total weight of polymer, and the impregnating agent is dried. 3. Method as stated in claim 2, characterized in that the fibrous web is completely impregnated by coagulation. 4. Method as stated in claim 3, characterized in that the fibrous web has a bulk density of less than 0.5 g/cmf. 5. Method as stated in claim 2, characterized in that the polyurethane polymer and the other polymer are present in the web in an amount of at least 70% by weight as occupied material based on the weight of the fibrous web. 6. Method as stated in claim 2, characterized in that the impregnated fibrous web has a density of up to 0.75 g/cc. 7. Impregnated fibrous web comprising a fibrous web impregnated with a homogeneous mixture of a coagulated anionic dispersion of a polyurethane polymer and a compatible (miscible) anionic, cationic or nonionic dispersion or emulsion of a polymer selected from the group consisting of neoprene . 8. Impregnated fibrous web as stated in claim 7, characterized in that the homogeneous mixture of anionic coagulated polyurethane dispersion and a compatible (miscible) polymer dispersion or emulsion is distributed throughout the entire fibrous web with a completely uniform density of the impregnated fibrous web , the bulk density of the fibrous web is less than the actual density of the fibrous web so that it is porous, and the impregnated web has filaments both coated and uncoated with polymer resin, and concentrations of polymer resin. 9. Impregnated porous fibrous web as stated in claim 8, characterized in that the polyurethane and the other polymer are present in an amount of at least 70% by weight based on the weight of the fibrous web. 10. Synthetic layer sheet material comprising a polymer impregnated>; fibrous mass with a grain layer that forms a surface, the grain layer having a current density equal to the layer's bulk density and a gap layer that forms the opposite surface, characterized in that the polymer consists of a coagulated anionic polyurethane dispersion and a coagulated polymer dispersion that is compatible (miscible) with polyurethane dispersion the ion.