NL8104173A - IMPREGNATED NONWOVEN SHEETS AND PRODUCTS MADE THEREOF. - Google Patents

Description

1; i -i * 'N.o. 30,391

Impregnated non-woven sheet material and products made therewith,

The invention relates to resin impregnated fiber webs and more particularly to resin impregnated fiber webs having uniform density throughout and to products thereof.

5 Resin-impregnated sheet materials, such as cloth, wick, layers of water (water leaves) and the like are well known. These resin impregnated sheet materials can be used for a wide variety of purposes including imitation leather in the form of vinyl and the like, structural sheet materials such as conveyor belts, and the like.

Known methods for impregnating a particular web include impregnating or coating a porous material with a polymeric resin such as polyurethane, vinyl or the like.

Polyurethanes have been widely used as a coating or an impregnating agent due to the ability of a wide variety of chemical and physical properties, in particular their flexibility and chemical resistance. Various methods have been used in impregnating a porous sheet-like material with a polymer resin. Such a known method involves the use of the polymer resin in an organic solvent in which the sheet material is dipped in the solution and the solution is removed therefrom. These solvents are undesirable because in many cases the solution is toxic and must either be recovered for reuse or discarded.

These solvents are expensive and do not necessarily give a desired product because upon evaporation of the solvent from the impregnated porous sheet material, the resin tends to migrate and provides a non-homogeneous impregnation of the porous sheet material resulting in an excess resin near the surface of the sheet material rather than a uniform impregnation.

Various aqueous polymer systems have been proposed to reduce the problems with solvents. When forming impregnated sheet materials by impregnation with aqueous polymers, the aqueous portion must be removed. This is also 8104173. ? 2 requires heat and migration of the polymer to the surfaces of the impregnated sheet material occurs.

In a method of combining polyurethane solvents with porous substrates, the polymer is applied in an organic solvent to a substrate, such as a needle punched polyester wick. The polymer substrate assembly is then washed with a mixture of organic solvent for the polymer and a non-solvent for the polymer that is at least partially miscible with the solvent until the layer 10 is coagulated in a cellular structure of interconnected micropores. The solvent is removed from the coating layer along with the non-dissolving agent to form a solvent-free macroporous layer. While this process gives acceptable properties for a polyure-15 than impregnated textile material, it has the drawback that an organic solvent is used in part as high performance polyurethanes that require relatively toxic and high boiling point solvents. An example of this method is described in U.S. Pat. No. 3 * 208,875 · In another method, dispersions in organic carriers have been proposed and used to coat porous substrates as described in U.S. Patent 3,100-721. In this system, a dispersion is applied to a substrate and coagulated by further addition of a non-dissolving agent. Although this approach has been used with some success, it includes two major limitations: (1) the dispersion support is essentially organic because relatively small amounts of non-solvent, preferably water, are necessary to form a dispersion; and (2) there is a narrow useful range of added non-solvent so that reproducible results are difficult to obtain.

A particularly suitable method of manufacturing composite sheet material by impregnating a porous substrate is described in U.S. Patent 171 * 391 · 35 In this system, a porous sheet material is impregnated with an aqueous ionic dispersion of a polyurethane and the impregnant is coagulated therein . The assembly is then dried to form a composite sheet material. The invention is an improvement on this basic method kO and in certain cases has a broader scope.

810 4 17 5 * i 3

Impregnated porous substrates and similar materials have been proposed as substitutes for leather for the purpose of manufacturing a product that has the same properties as natural leather.

5 Natural leather that has been suitably processed is of value because of its durability and aesthetic properties for a wide variety of applications. Due to the scarcity of leather and increased costs of leather treatment for certain applications, the costs have contributed to substituting synthetic materials for it in certain applications where leather goods are used. Such synthetic materials have been proposed and used in the fields of shoe uppers, upholstery, clothing, case making, book binding and the like. Because these different applications require different physical, chemical and aesthetic qualities, different methods using different materials must be used to obtain an acceptable product comparable to natural leather, although in most cases these synthetic materials can be easily distinguished of natural leather.

Natural animal skin leather is composed of two planes: a plane forms the grain layer which is aesthetically desirable in most cases and the opposite plane which forms the splitting layer. The grain layer is the epidermis of the animal and is very smooth while the splitting layer is in most cases rough and fibrous *

A method of manufacturing a synthetic material as a substitute for leather comprises impregnating and / or coating a porous material, for example, cloth with a polyurethane, a vinyl or a similar material. Polyurethanes are preferred as a coating or impregnation material due to their ability of a wide variety of chemical and physical properties, in particular flexibility and chemical resistance.

Purposes for the manufacture of synthetic leather substitute materials are that they provide: (1) sheets which are particularly suitable for use similar to leather and for coatings applications; (2) sheets of the same width as commonly used in the textile industry (in contrast to natural products, which have an important weight and surface losses during cutting and finishing); (3) the variety of final uses, for example, under a wide range of conditions of use where certain chemical treatments contribute to the maintenance and longevity of properties; and most importantly, (4) a product having a strength, grip, drape and softness comparable to natural leather.

Furthermore, a counterfeit leather skin material, indifen used for shoe uppers, should be characterized by a leather-like appearance, so that no unwanted material is visible, by good water vapor permeability in the uncoated sides of the upper and a leather grain print ( minimum strong wrinkling). "Leather-like grain breakage" as present in leather and upholstery industries is evident in the behavior of well-finished leather when it is folded or wrinkled. The leather fold is characterized by a smooth curved shape, often with a large number of small folds in the compressed part of the fold area. This is in contrast to sharp edges or heavy folds formed when paper or film is folded; this type of unwanted appearance is known as "pen crease".

The leather grip is very defining and synthetic materials usually have a rubbery feel, unlike leather.

Polyurethane polymers such as coatings or impregnating agents for textiles to provide replacements for leather have long been known. For example, polyurethanes can be formed which are highly resistant to solvents and abrasion, due to the possibility of dry cleaning and excellent durability of coated materials. The basic chemistry of polyurethanes, comprising reactions between the isocyanate groups and molecules. with multiple reactive hydrogen, such as polyols and polyamines, provide great versatility and variation in the final chemical and physical properties through the choice of intermediates to achieve the machining capability and the desired balance of final performance requirements .

There are several methods for applying polyurethane solutions or other latar vulcanizable liquid KO polymers to porous substrates that are readily apparent to one skilled in the art. An article in "Journal of Coated Fabrics, Vol. 7 (July 1977) * pp. 43 to 57 describes a number of commercially available fence systems, i.e. reversible roll coatings, container fed coatings apparatus * engraving and the like * Brushing and spraying can also be used to apply polyurethanes to porous substrates. * These polyurethane solutions are dried or vulcanized after impregnating or coating the substrate by a method using heated air * infrared radiation and the like. these methods is to place a polymer and a film-shaped layer which tends to form a coated material that folds with undesirable sharp fold lines rather than grain breakage in leathery material Other methods of combining polymer solutions and in particular polyurethane solutions with porous substrates are described in U.S. Patents 3 * 208 .875 and 3 * 100 * 721.

An improved method of impregnating textile materials is disclosed in US Patent 4 * 171 * 391 * which method includes certain steps necessary to form a faux leather sheet material in accordance with the invention.

According to the invention, a method is described for impregnating porous sheet-like materials and in particular needle-punched slivers, whereby a uniform impregnation is provided in an aqueous system which forms a product with high tear strength and high integrity.

Furthermore, an impregnated fiber web is provided which has a novel and unusually useful structure suitable for use as a molded or subsequently treated material 30 to obtain further advantages.

Furthermore, according to the invention, a counterfeit sheet-like leather material is formed which has the appearance and properties of natural leather and furthermore certain physical similarities therewith.

A resin-impregnated fiber layer is composed of a needle punched fiber web and a polymer resin distributed throughout the web. The density of the impregnated web is uniform throughout, with the mass density of the web less than the actual density of the web so that the web is porous. The impregnated web has elemental threads that are both coated and uncoated with -bet polymer resin. A method of forming impregnated fiber web is also discussed.

A fake leather sheet material is made from the impregnated web. The counterfeit leather sheet is composed of a polymer impregnated fiber mass with a grain layer forming one surface and a splitting layer forming the opposite surface. The grain layer has an actual density equal to its volume density and the splitting layer has a volume density less than its actual density. The sheet-shaped material has a density that decreases from the grain layer to the splitting layer.

By "volume density" as used herein is meant the density of the material also including the airspace. "Actual density" is used herein and refers to the density of the material without the airspace, ie, specific gravity.

The fiber mass useful in the practice of the invention includes woven and knitted fabrics, felt and nonwoven materials, such as spun-bonded sheets, needle punched sheets and water-laid tapes, and suitable substrate fibers. the natural fibers, in particular cotton and wool; synthetic fibers such as polyester, nylon, acrylic, modacrylic and rayon * It is preferred that the fiber mass consists of needle punched fiber layers formed from these natural and synthetic fibers. Preferably, the fibers have a denier of 1 to 5 and a length suitable for carding which is, in particular, 2 to 15 cm, and more particularly 3 to 8 to 6 cm.

The needle punched fiber wicks can be either high, intermediate or low density. The high density wicks have a maximum density of 0.5 g / cm3. * These very dense wicks are, in particular, composed of wool. When synthetic fibers are used to form the slivers, the high density slivers have a density of 0.25 g / cm. In the practice of the invention, the fiber splices preferably have a density of 0.08 to 0.5 g / cm. The thickness of the fiber slivers can be 1.3 cm and preferably 0.3 to 1 cm with a minimum thickness of 0.08 cm. In addition, the wicks have been characterized as "saturation wicks", which have a high cohesion due to the needle pricks, as opposed to light ifO bonded wicks, which have a small number of needle pricks with little or no integrity.

The polymer resins useful in the practice of the invention are preferably those polymer resins which are capable of dissolving, dispersing or emulsifying in water and subsequently coagulating from the water system with an ionic coagulant.

A preferred polymer system is a polymer system composed of acrylic monomers, such as alkyl acrylates and methyl acrylates, from acrylonitrile, methyl acrylonitrile, and other well-known acrylic monomers. These acrylic monomers can be polymerized by emulsion polymerization to form a latex or other systems to form free radicals and then dissolve or emulsify in water. The solvent or solubilizing system must be such that when the emulsion comes into contact with concentrated acid or a concentrated base, the polymer coagulates from the aqueous system and is rendered essentially insoluble.

In particular, emulsified or water-dispersed polyurethanes are used. Examples of emulsified poly-urethanes are those described in U.S. Patent 2,968 * 5751 which are prepared and dispersed in water using detergents under the influence of high shear.

When these polyurea emulsions are formed, the emulsifier or detergent must be one that is ionic in nature so that a counterion can be added to the aqueous system to coagulate the polymer. More particularly, the polyurethanes useful in the practice of the invention are those which are indicated in practice as ionic water dispersible.

The preferred system for forming ionic aqueous polyurethane dispersions is to form polymers that have free acid groups, preferably carboxylic acid groups covalently bonded in the polymer backbone. Neutralization of these carboxylic acid groups with an amine, preferably a water-soluble monoamine, provides dilution in water. Careful selection of the substance bearing the carboxylic acid group must be made because isocyanates, necessary substances in any polyurethane system, are generally reactive with carboxylic acid groups. However, as described in U.S. Pat. No. 3 ^ 12.05½, 2,2-hy-ifO droxymethyl-substituted carboxylic acids can be reacted with organic polyisocyanates without a clear reaction between the acid and isocyanate groups due to steric hinderance of the carboxylic acid group by the adjacent alkyl groups. This approach provides the desired carboxyl-containing polymer wherein the carboxylic acid groups are neutralized with the tertiary monoamine to provide an internal quaternary ammonium salt and thus water dilutability.

Suitable carboxylic acids and preferably the sterically hindered carboxylic acids are well known and readily available. Preferably, they can be prepared from an aldehyde containing at least two hydrogen atoms in the α position which are reacted in the presence of a base with two equivalents of formaldehyde to form a 2, 2-hydroxymethylaldehyde. The aldehyde is then oxidized to the acid by a method known to one skilled in the art. ·. Such acids have the formula of FIG. 8 wherein E is hydrogen or an alkyl of up to 20 carbon atoms and preferably up to 8 carbon atoms. A preferred acid is 2> 2-di- (hydroxymethyl) -propionic acid. The polymers with the carboxyl groups present are characterized as anionic polyurethane polymers.

Furthermore, according to the invention, another way to provide water solubility is to use a cationic polyurethane with amino groups present. Such cationic polyurethanes are described in U.S. Pat. No. 0,666,391. In the present invention, it is preferred that the anionic polyurethanes be used.

The polyurethanes usable in the practice of the invention more particularly involve the reaction of di- or polyisocyanates and substances with a number of reactive hydrogen atoms suitable for the production of polyurethanes. Such diisocyanates and reactive hydrogen-containing substances are more Further described in detail in U.S. Pat. Nos. 3,412,034 and 4,0if6,729. Furthermore, the methods of preparing such polyurethanes are well known as exemplified in the above-referenced patents. In accordance with the invention, aromatic aliphatic and cycloaliphatic diisocyanates or mixtures thereof are used to form the polymer. Such diisocyanates are, for example, tolue en-2} if-diis ocyanate, tolyl and-2} β-diisocyanate, meta-pheny-40-borne diisocyanate, biphenylene-4, if-diis-cyanate; methylene bis-8104173 9 (1 (-phenylisocyanate), t-c & loor-1-phenylene diisocyanate; naphthylene-1,5-diisocyanate, tetramethylene-1, if-diisocyanate hexamethylene-1,6- diisocyanate; decamethylene-1,10-diisocyanate; cyclohexylene-1, if-diisocyanate; methylene-bis (if-cyclohexyl isocyanate); tetrahydronaphthylene diisocyanate; isophorone diisocyanate and the like. preferably used in carrying out the invention day.

In particular, the aryleadiisocyaaatea include those wherein the isocyanate group is bonded to the aromatic ring. The most preferred isocyates are the 2, ½ and 2.6 isomers of tolylene diisocyanate and mixtures thereof due to their easy availability and their reactivity. Furthermore, the cycloaliphatic diisocyanateea, which are preferably used in the practice of the invention, are if, V-methylene bis (cyclohexyl-15 isocyanate) and isoporoadiisocyanate.

Selection of the aromatic or aliphatic diisocyanates is determined by the final use of the material. It will be apparent to one skilled in the art that aromatic isocyanates can be used if the final product is not excessively exposed to ultraviolet radiation which tends to yellow such polymer compositions while the aliphatic diisocyanates may be more preferably used in outdoor applications and less tendency to yellow when exposed to ultraviolet radiation. Although these data provide a general basis for the choice of the isocyanate to be used, the aromatic diisocyanates can be further stabilized by known ultraviolet stability. sizing agents to enhance the final properties of the polyurethane impregnated sheet material. In addition, antioxidants can be added to improve a real value value of the properties of the final product. Particular antioxidants are thioethers and phenol-like antioxidants such as 1f, V-butylidene bis-meta-cresol and 2,6-di-tert-butyl para-cresol.

The isocyanate is reacted with the number of reactive hydrogen-containing substances such as diols, diamines, or triols. In the case of diols or triols, they can typically be either polyalkylene ether or polyester polyols. A polyalkylene ether polyol forms the preferred active hydrogen-containing polymeric material for formulating the 8104173

Μ Q

Polyurethane 10. The most useful polyglycols have a molecular weight of 50 to 10,000, and within the scope of the invention, about 100 to 700 are preferred. Furthermore, the polyether polyols proportionally improve flexibility as their molecular weight increases by 3 *

Nonlimiting examples of the polyether polyols are polyethylene ether glycol, polypropylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyoctaethylene ether glycol, polydecamethylene ether glycol, polydodecamethylene-tetraglycol and mixtures thereof. Polyglycols containing a number of different radicals in the molecular chain, such as, for example. , larger picture the compound HO (C ^ OC ^ H ^ Oj ^ H, where n is an integer / than 1, can also be used.

The polyol can also be a polyester with terminal hydroxyl groups and / or hydroxyl groups present instead of or in combination with the polyalkylene ether glycols. Thus, examples of such polyesters were 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-propanedial, cyclic glycols such as cyclohexanediol and aromatic glycols. Aliphatic glycols are generally preferred when flexibility is required. These glycols are reacted with aliphatic, cycloaliphatic or aromatic dicarboxylic acids or alkyl esters with a small number of C atoms, or esters that form derivatives to form polymers of relatively low molecular weight, preferably with a melting point less than about 70 ° C and a molecular weight equal to that indicated for the polyalkylene ether glycols. Acids for preparing such polyesters are, for example, phthalic, malex, amber, adipine, cork, sebacin, terephthalic and hexahydrophthalic acids and the alkyl and halogen-substituted derivatives of these acids. In addition, poly-caprolactone with terminal hydroxyl groups can also be used.

A particularly suitable polyurethane system is the cross-linked polyurethane system described in U.S. Patent Application 9h7-5kk of October 2, 1978

By "ionic dispersant" is meant an ionizable acid or ionizable base that can form a salt with the carbonating agent. These "ionic dispersants" are 8104173-11 amines, and preferably water-soluble amines such as triethyl amine, tripropylamine N-ethylpiperidine, and the like; also acidic and preferably water-soluble acids such as acetic acid, propionic acid, lactic acid and the like. Of course, an acid or an amine is selected depending on the solubilizing group of the polymer chain present.

The desired elastomeric behavior generally requires about 25 to 80 weight percent of a long chain polyol (i.e., 700 to 2,000 equivalent weight) in the polymer. The degree of stretch and elasticity can vary widely from product to product depending on the desired properties of the final product.

In polyurethane molding useful in the practice of the process, the polyol and a molar excess of diisocyanate are reacted to form a polymer with isocyanate-terminated polymer. Although suitable reaction conditions and reaction times and temperature vary within the scope of the particular isocyanate and polyol used, these variations will be apparent to those skilled in the art. It will be apparent to those skilled in the art that the reactivity of the respective constituents requires a balance of the reaction rate with undesired secondary reactions that give rise to color and molecular weight degradation. Specifically, the reaction is conducted with stirring at about 50 ° C to about 120 ° C for 1 to k hours. To provide adherent carboxyl groups, the polymer with terminal isocyanate is reacted with a molar deficiency amount φ. Known Hydihydroxyacid for 1 to if hours at 50 to 120 ° C to form a prepolymer with isocyanate terminal. The acid is preferably added as a solution, for example in 50 N-methyl-1,2-pyrrolidone or Ν, Ν-dimethylformamide. In particular, the acid solvent is not more than about 5% of the total amount to minimize the concentration of organic solvent in the polyurethane composition. After the dihydroxy acid has reacted with the polymer chain, the adjacent carboxyl groups are neutralized with an amine at about 58-75 ° C for about 20 minutes and chain extension and dispersion are obtained by adding water with stirring. A water-soluble diamine can be added to the water as a further chain extender. The chain extension includes a response from 8104 173. w ....

12 ♦ residual isocyanate groups with water to form urea groups and further polymerize the polymeric material, as a result of which all isocyanate groups are reacted as a result of the addition to a large stoichiometric excess of water · It should be noted that the polyurethanes according to the invention are of a thermoplastic nature, i.e. are not capable of excessive further vulcanization after their formation except the addition of an external vulcanizing agent. Preferably, no such vulcanizing agent is added to form the composite sheet material.

Sufficient water is used to disperse the polyurethane at a concentration of about 10 to about 10 wt% solids and a dispersion viscosity within 10 to 1,000 centipoise. The viscosity can be adjusted in accordance with the special impregnation properties desired, and by the special dispersion composition, all of which are determined by the properties of the final product. It will be understood that no emulsifiers or thickeners are required for the stability of the dispersions.

Those skilled in the art will appreciate the various ways of modifying the primary polyurethane dispersion in accordance with the final product, for example, by adding colorants, compatible vinyl polymer dispersions, ultraviolet filters, oxidizing stabilizers, and the like.

The characterization of the dispersions prepared according to the invention is carried out by measurements of the non-volatile content, the particle size, viscosity measurements and by stretch properties on strips of cast film.

The concentration range useful in practicing the invention is determined by the desired percent addition of polymer in the sewn wick.

The dispersion viscosity is generally in the range of 10 - 1,000 centipoise. The low viscosity, relative to that of identical polymers with the same solids content in polymer solutions with organic solvent, contributes to rapid and complete penetration of the aqueous dispersion and subsequent penetration of the coagulant. In contrast, useful polyurethane solutions generally have viscosities of many thousands of centipoises, up to 8104173 13 50,000 centipoise at concentrations of 20-30% ·

The polymers should be impregnated into the fiber wick to a level of at least 70 weight percent filler material based on the weight of the fiber wick and up to about 400 weight percent. Preferably, the polymer resin is impregnated in an amount of from about 200 to 300 weight percent additive based on the weight of the fiber wick.

Coagulation is carried out by contacting the impregnated substrate with an aqueous solution of an ionic agent intended to ionically replace the solubilizing ion. In theory, although not intended to be limited theory, in the case of an anionic solubilized polymer, the amine which neutralizes the carboxyl-containing polyurethane is replaced by a hydrogen ion which converts the anionic carboxyl ion back and thus the polymer back to its original, rhite-dilutable state, causing coagulation of the polymer in the substrate structure.

In the case of anionic polymer, aqueous acetic acid-20 solutions and concentrations from 0.5% to about 75% are a suitable ionic coagulant for anionic dispersions and are preferred over stronger acids because of their relatively easy handling, low corrosion resistance. potential and good availability.

25 "Salt salts" to coagulate the dispersion by adding the neutral salt is practicable but is not preferred because of the necessary large amounts of salt, about ten times the concentration of acid, and associated problems of contamination of the product.

When impregnating the needle punched wick with polymeric resin as described herein, the wick is immersed in an aqueous ionic emulsion or dispersion at a concentration level 4 sufficient to provide an addition of at least 70% wt. After immersing the wick in the aqueous emulsion or dispersion, the wick can be squeezed to remove air to provide complete impregnation of the emulsion or dispersion in the wick. The wick, now fully impregnated with the aqueous dispersion or emulsion, is passed through wis-rollea or the like to remove the excess dispersion or emulsion from the surface of the impregnated wick. The wick is then immersed in a bath containing a counterion to provide coagulation, the counterion containing material which penetrates the wick by causing diffusion and coagulation of the resin into the fiber structure. After coagulation, the wick is squeezed to remove the excess water and dried to form an impregnated web.

This method is a further improvement of the method known from United States Patent Specification K · 171 * 391 with regard to the provision of special products. The differences between the latter patent and the method according to the invention are that the wick is completely saturated, ie no retained air space with the aqueous dispersion or emulsion that a final addition of at least 70% by weight of polymer resin based on the weight of the wick provided. As a result of these differences, a new structure is obtained in which the wick has a uniformly uniform density and the volume density of the web is less than the actual density of the web.

After the impregnated web has been formed, it is given a density gradient to form a sheet-like leather. When the sheet-like imitation leather is formed, the web impregnant preferably consists of granular polymers capable of fusing together under conditions of heat and pressure. Normally these polymers are thermoplastic; however, certain cross-linked polymers capable of coalescence can also be used. More particularly, polyurethanes as described in U.S. Patent Application 9k7,5kb of October 2, 1978 have been found to be particularly useful in practicing the invention to develop the desired density gradient over the thickness of the material.

The characteristic features of the counterfeit sheet material according to the invention are primarily physical properties, providing a density gradient 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 fiber mass forms the grain layer, the grain layer having an actual density equal to its volume density.

This grain layer accurately simulates the grain of natural leather. On the opposite side of the sheet material bO, there is a surface that forms the splitting layer which has a volume density less than the actual density, preferably having a uniform density gradient across the material. The splitting layer is slightly fibrous and simulates the splitting layer of natural leather.

He-c polymer is present in the counterfeit leather sheet to a level of at least 70 wt% addition based on the weight of the fiber mass.

In particular, the splitting layer has a density of about 73% of the density of the grain layer to provide a porous grain layer that simulates the leather grain layer. It should also be noted that the polymer is evenly distributed throughout the fiber mass in a manner in which the fiber to polymer ratio is thoroughly uniform *

The simulated leather sheet is manufactured by treating the impregnated fiber mass and preferably an impregnated nonwoven sheet material, as described above.

It is particularly preferred if the polymer used for impregnation is one of the materials described in U.S. Patent Application No. 947 * 544 · ZO above, in a treatment method of the impregnated nonwoven sheet material to form the simulated leather sheet , the impregnated nonwoven sheet material is placed in a press and heat and pressure are applied to both sides thereof * The heat and pressure are sufficient to melt the polymer together into the impregnant on the surfaces of the material, yet insufficient to completely melt the polymer into the interior of the sheet material. This method develops a density gradient from the interior of the nonwoven sheet material to the two exterior surfaces. The dimensions of the thickness of the heated and compressed material can be controlled by the pressure applied during the heating and pressing or by inserting spacers between the press plates or by using a dead load press.

The plates of the press may be further embossed to provide a specific surface finish to the material. In pressing, the material is split from the center to provide two simulated leather sheets each having a grain layer and a splitting layer.

40 In another method of forming the simulated 8104173 '. · 16 leather sheet, the impregnated nonwoven starting material »discussed above can be placed in a press of which only one of the plates is heated to form a grain layer while the opposite side on the cool plate forms the splitting layer .

In yet another method of forming the simulated leather sheet, two pieces of impregnated nonwoven raw material discussed above can be superimposed in a press and heat and pressure can be applied sufficiently to melt the polymer in the impregnating agent on the outer surface of each piece. After pressing, the individual pieces are separated resulting in two sheets of simulated leather.

Following molding, the simulated leather can be ground, coated, or further treated as known in other leather finishing methods.

In yet another method, the development of the grain layer can be achieved on unwrapped strips of impregnated nonwoven stock which is unwound from wrappers 20 and passed through a pair of calender treatment rollers. Preferably, one of the rolls is metal, heated to 150 to 200 ° C, and is smooth or suitably embossed; and the other roll is a soft resilient roll, such as rubber. The grain layer is developed on the metal roll side of the sheet. Effective calendering 25 can generally be performed with a load from 5 to ......

15 kg / m width of the sheet passing through the rollers. Wetting the sheet prior to calendering up to 50 to 100 wt.% Added water can aid calendering.

The structure of the impregnated web and the simulated leather is more clearly visible in the accompanying drawing, which shows cross-sectional micrographs of an impregnated web and simulated sheet leather manufactured in accordance with the invention.

Fig. 1 shows a plan view of a resin impregnated web prepared according to Example I for splitting.

Fig. 2 shows a micrograph of the thickness of the web of FIG. 1 along the line II-II.

Fig. 5 shows a micrograph with 100 times magnification of section III in FIG. 2.

lj.0 Fig. if shows a 100 times enlarged micrograph of the IV section 8104173 17 according to fig. 2.

Fig. 3 is a 100 times enlarged micrograph of section V according to FIG. 2 *

Fig. 6 is a 100-fold enlarged micrograph of a resin 5 impregnated wick prepared according to Example 1 after wear.

Fig. 7 is a 100-fold cross-sectional enlargement over the thickness of a simulated leather sheet made from the wick of FIG. 6.

Fig. 8 shows the structural formula of an used acid.

In Figs. 1 to 5 * in which corresponding parts are represented by the same reference numerals, a resin impregnated web 10 is shown manufactured according to example I. More specifically, Figs. 2 to 5 show a cross section over the thickness of the web 10. The web 10 is composed of an upper surface 15 12 and a lower surface 14. The web 10 contains a large number of uncoated fibers 16, resin concentrations 20, cavities 18 and resin coated fibers 22. Its structure and volume density is essentially the same throughout the thickness of the material, although on a microscopic scale the structure is not homogeneous.

The structure shown in Figs. 2 to 5 is believed to contribute to completely impregnating the needle-pricked wick with the aqueous solution or dispersion and subsequent coagulation of the polymer while the wick is fully impregnated with the aqueous resin system.

In Fig. 6, a micrograph is shown in 100 magnification and shows a split impregnated needle punched wick 24 having a uniform uniform density as shown in Figs. 1 to 3. The impregnated wick 24 has a large amount of coated fibers 26 amounts of polymer 2δ, coated fibers 32 and voids 30. It should be noted that although the impregnated wick is not homogeneous on a microscopic scale, it has a thorough volume density.

In Fig. 7, which shows a 100-fold magnification of a micrograph, the simulated leather sheet 32 according to Example IV is shown. The material 32 has a grain layer 34 which has minimal cavities and a volume density of the grain layer 34 is equal to the actual density. On the grain layer 34, an assembly 36 of fibers is formed in a continuous resin matrix as a result of the application of heat and pressure * Moving in the direction A 40, it appears that the cavities 30 increase in the direction approaching the split 8104173 18 layer 3 * In the splitting layer 38 contains a large number of voids 30i uncoated fibers 26 and polymer amounts 28 · The structure of the splitting layer 38 approximates the structure shown in FIG. 6. The following examples describe the products manufactured according to the invention.

Example I

A needle-pricked wick which was heat-set and had a density of 1200 g / m composed of polyester-10 »polypropylene». and rayon fibers with a thickness of 0.8 cm with a volume density of 0.16 g / cm was immersed in a polyurethane manufactured in accordance with Example III of US patent application 9k7 * 5kki mentioned above.

The polymer dispersion had a total of 22% solids for 13 to provide a 120% addition based on the weight of the wick. The wick was immersed in the polyurethane dispersion for 10 minutes at room temperature until all air was removed from the interior of the wick and the wick was fully impregnated »The surface of the wick was wiped with a straight edge on both sides for removal of the excess aqueous dispersion and immersed in a 10% acetic acid bath for 10 minutes at room temperature. Acid immersion fully coagulated the polyurethane within the fiber structure * The excess acetic acid was washed from the wick and the resin-impregnated wick was squeezed to remove the excess water »The resin-impregnated wick was split into four layers over its thickness and each split layer was dried at 130 to 177 ° C in a circulating air oven to form four resin-impregnated webs with a volume density of 0.1 g / cm 2. The micrograph of the product corresponds to that of the drawing.

Example II

Example I was repeated with the exception that a sliver of 100% polyester with a density of 0.13 g / cm 3 and a thickness 33 of 0.3 cm was impregnated with a dispersion according to example I with 22% solids. The impregnated web obtained had a thoroughly uniform density, high integrity and a volume density of 0.38 g / onP,

Example III

Example I was repeated with the exception that a 8104173 19 χ.

Needle-pricked wick of 100% polyester with a thickness of Tan 0.56 cm and a density of 0.23 g / cm 2 was impregnated with a dispersion with 32% solids to form needle-punched resin-impregnated fiber web with a volume density of 50 * 56 g / cm 2. The product of Example 3 was used as a polishing cloth and was tough, had a high tear strength, a high resilience and a complete recovery after compression.

Thus, the method and product of the invention provides an impregnated high integrity fiber web and is useful as a product in itself and useful for forming other products. Furthermore, the impregnated fiber web can be polished to provide a desired finish.

Example IV

Split parts with a thickness of 0.18 cm of the non-woven impregnated web, manufactured according to example I, were placed on top of each other and between the plates of a press was heated to 150 ° C at a pressure of 35 kg / m for 30 seconds. The two splice layers were then peeled apart to yield two layers of simulated leather material. The grain of the sheets corresponds to the surfaces in contact with the hot press plates. The inner sides of the sheets retained their fiber texture similar to that of an unpressed sheet. Microscopic examination revealed that the simulated leather had a density gradient from the grain layer to the splitting layer as shown in Figure 7.

The simulated leather can be post-treated with other surface finish polymers after molding in accordance with techniques known per se.

30 * • r 8104173

Claims (21)

1. Resin-impregnated fiber web characterized by a needle punched fiber wick, a polymer resin distributed by said wick to form a resin-impregnated fiber web, the density of the impregnated fiber web being uniform throughout, the volume density being The web is less than the actual density of said web, making the web porous, and the impregnated web having filaments both coated and uncoated with polymer resin. Resin-coated fiber web according to claim 1, characterized in that the needle punched fiber wick has a volume density of less than 0.5 g / cm 2. Resin impregnated fiber web according to claim 2, characterized in that the needle punched fiber wick has a z volume density of less than 0.25 g / cm. Resin impregnated fiber web according to claim 2, characterized in that the needle punched fiber web has a volume density ranging from 0.12 to about 0.4 g / cm 2. Resin-impregnated fiber web according to claim 1, characterized in that the needle punched fiber wick has a thickness of at least 0.75 mm. Resin-impregnated fiber web according to claim 1, characterized in that the needle punched fiber wick is composed of substantially non-fusible fibers. Resin-impregnated fiber web according to claim 1, characterized in that the polymer resin is a polyuran. Resin-impregnated fiber web according to claim 7, characterized in that the polyurethane is water-dispersible polyurethane. Resin-impregnated fiber web according to claim 7, characterized in that the polyurethane is a cross-linked polyurethane. Resin impregnated fiber web according to claim 1, characterized in that the polymer resin is a polyacrylate. 11 * Resin impregnated fiber web according to claim 1, characterized in that the polymer resin is present in an amount of at least least 70 wt.% addition based on 8104173 on the weight of the fiber wick * Resin-impregnated fiber web according to claim 11, characterized in that the polymer resin is present in an amount of less than about 400% by weight of addition 5 based on the weight of the fiber wick - 13 * Resin-impregnated fiber web according to claim 12 characterized in that the polymer resin is present in an amount of about 200 to 300 weight percent addition based on the weight of the fiber wick. Resin-impregnated fiber web according to claim 1, characterized in that this web has a density of at most about 0.73 g / cm. Resin-impregnated fiber web according to claim 14, characterized in that it has a density ranging from about 0.4 to about 0.75 g / cm. A method of forming an impregnated fiber web characterized by fully saturating a needle punched fiber wick with an aqueous dispersion or emulsion of an ionically solubilized polymer resin, contacting the fully saturated needle punched wick with an ionic coagulant around the polymer resin to coagulate from the aqueous dispersion and apply to the polymer resin within said needle punched wick, and drying the needle punched wick and the polymer resin to form an impregnated fiber web of uniform density throughout. Method according to claim 16, characterized in that the needle punched wick has a volume density of less than 0.5 g / cm. 18. A method according to claim 17, characterized in that the needle punched fiber wick has a volume density of less than 0.25 g / cm. Method according to claim 17, characterized in that the needle punched fiber wick has a volume density of between 0.12 and 0.4 g / cm. Method according to claim 1, characterized in that the needle punched fiber wick has a thickness of at least 0.75 cm. 21. A method according to claim 16, characterized in that the needle punched fiber wick is composed of substantially non-fusible fibers, method of claim 16, characterized in that the polymer resin is a polyurethane. A process according to claim 16t, characterized in that the aqueous dispersion or emulsion has a content of 3 solid particles of about 3 to 60% by weight. Method according to claim 22, characterized in that the polyurethane is cross-linked. Method according to claim 16, characterized in that the polymer resin is present in the web in an amount of at least 7 ° wt. Addition based on the weight of the fiber wick. Method according to claim 251 with characterized in that the polymer resin is present in an amount of less than about 400 weight percent addition based on the weight of the fibers. 27. A process according to claim 26, characterized in that the polymer resin is present in an amount of about 200 to 300% by weight of addition based on the weight of the fiber wick. A method according to claim 16, characterized in that the impregnated fiber web has a density of up to about 0.75 g / cm 2. 29. A method according to claim 28, characterized in that. that the impregnated fiber web has a density ranging from about 0.4 to about 0.75 g / cm. Simulated leather sheet characterized by a polymer-impregnated fiber mass with a grain layer forming a surface, the grain layer having an actual density equal to its volume density and a splitting layer forming the opposite surface, which splitting layer having a volume density less than its actual density, which layer material has a density that decreases from the grain layer to the splitting layer, the fiber to polymer ratio being uniform over the entire sheet material. 31. The material according to claim 30, characterized in that the fiber mass is a needle punched wick. 32. A material according to claim 30, characterized in that the polymer is a polyurethane. Material according to claim 32, characterized in that the polyurethane is cross-linked, 8104173: 23 α 3b. Material according to claim 30, characterized in that the polymer is present in an amount of at least 75 wt. 96 addition based on the weight of the fiber mass. The material of claim 3b characterized in that the polymer is present in an amount up to 400% by weight based on the weight of the fiber mass. 36 * Material according to claim 35, characterized in that the polymer is present in an amount of 200 to 300 wt% addition based on the weight of the fiber mass. Material according to claim 30, characterized in that the splitting layer has up to 75% of the density of the grain layer. The material according to claim 30, characterized in that the polymer is uniformly distributed throughout the fiber mass. The material according to claim 30, characterized in that the density of the sheet-like material has a uniform gradient from the split side to the grain side. bO, a method of forming a simulated leather sheet characterized by a uniform impregnation of the fiber mass with a polymer to form a porous sheet-like material, heating the porous sheet-like material under the influence of heat and pressure, which heat and pressure is applied to at least one surface thereof to develop a simulated leather sheet having a grain layer on the surface to which the heat is applied, the grain layer having a volume density equal to the actual density, and a splitting layer having a volume density less than its actual density, which sheet material has a density that decreases from the grain layer to the splitting layer, and wherein the fiber to polymer ratio is uniform throughout the sheet material. 41. A method according to claim k0, characterized in that heat and pressure are applied to both surfaces of the sheet material to develop a density gradient from the exterior of the sheet material to the interior of the sheet material. and splitting the sheet material in half 40, wherein the sheets: i. internal surfaces form the grain layer and internal surfaces form the splitting layers * ***** * 810 4 1 73