SE452994B - HEARTSIMPREGNATED FIBROS COUNCIL INCLUDING A NEEDLE FIBROS PAD, WITH A ALSO SIMPLE DENSITY AS WELL AS PICTURE A HEARTSIMPREGNATED FIBROS COUNTRY - Google Patents

Description

ZS 40 452 994 containing polymers, the aqueous part must be removed. Again, heat is required and the migration of the polymer toward the surfaces of the impregnated sheet material is present.

In a method of combining polyurethane solutions with porous substrates, the polymer is applied in an organic solvent to a polyester wad of needled needles. The polymer substrate composite 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 coagulates into a cell structure with interconnected micropores. The solvent is removed from the coating layer together with the non-solvent to form a solvent-free, microporous layer. Although this process provides acceptable properties for a polyurethane impregnated fabric, it has the disadvantage of a system of organic solvent, especially when high performance polyurethanes are used, which require relatively toxic and high boiling solvents. An example of this method is described in U.S. Pat. No. 3,280,875.

In another method, polyurethane dispersions have been proposed in organic carriers and used to coat porous substrates, as described in U.S. Pat. No. 3,100,721. In this system, a dispersion is applied to a substrate and coagulated by further addition of a non-porous substrate. solvent. Although this problem solving has been used with some success, it involves two main limitations: Cl) the carrier in the dispersion is essentially organic, since relatively small amounts of non-solvent, preferably water, are required to form a dispersion, and (Z) it is a narrow useful range for added non-solvent, so that reproducible results are difficult to achieve.

A particularly valuable method for producing sheet-shaped composite materials by impregnating a porous substrate is described in U.S. Pat. No. 4,171,391, which is incorporated herein by reference. In this system, a porous sheet material is impregnated with an aqueous ionic dispersion of a polyurethane and the impregnating agent is coagulated therein. The composite is then dried to form a sheet-shaped composite material. The present invention is an improvement on this basic method and in some cases is further in its scope.

Impregnated, porous substrates and similar materials have been proposed as leather substitutes for the purpose of producing a product having the same properties as natural leather.

Natural leather, surface-treated in a suitable way, is valued for its durability and aesthetic properties for a number of uses. Due to the scarcity of leather and the increased cost of processing leather for special uses, the economy has guided the use of synthetic materials in certain areas of use where leather goods have been used. Such synthetic materials have been proposed and used in the fields of shoe leather, upholstery, upholstery, travel effect manufacturing, bookbinding and similar uses. While these different uses require different physical, chemical and aesthetic properties, different methods using different materials must be used to achieve an acceptable product, which is comparable to natural leather, although in most cases these synthetic materials are easily distinguishable from natural leather.

Natural leather from animal skins is composed of two surfaces: a surface that delimits the grain layer, which in most cases is In the most aesthetically desirable and opposite surface that delimits the slit layer. The grain layer is the animal's epidermis and is very smooth, while the cleft layer is in most cases pinched and fibrous.

One method of producing a synthetic material as a substitute for leather involves impregnating and / or coating porous material, for example fabric, with a polyurethane, polyvinyl compound or a similar material. Polyurethanes have been widely accepted as a coating or impregnating composition due to their ability to vary widely in chemical and physical properties, especially their flexibility and chemical resistance. The purposes of making synthetic substitutes for leather are that they provide: (1) sheets which are particularly suitable for leather-like use and upholstery; (Z) sheets of uniform width commonly used in the textile industry (unlike natural products, which undergo significant weight and surface loss during cutting and surface treatment); (3) versatility in end use, for example under a variety of exposure conditions, where certain chemical treatments will aid in the maintenance and valuable life of the properties; and most importantly (4) a product with strength, feel, fall and softness comparable to natural leather.

Furthermore, an imitation, sheet-like leather material when used for shoe leather should be characterized by a leather appearance without any undesirable fabric appearance, good water vapor permeability into the uncoated side of the upper leather and a leather grain break (minimal overall folding). ). "Leather-like grain breakage", as perceived in the leather and upholstery industries, manifests itself in the appearance of well-treated leather when folded or wrinkled. The leather fold is characterized by a smooth, curved contour, often with numerous fine folds in corresponding areas of the folded area. This is in contrast to sharp folds or total wrinkles, which are formed when paper or films are folded; this kind of undesirable appearance is referred to as "needle wrinkling".

The "feel" of leather is highly distinctive and synthetic materials normally have a rubber-like feel, which is in contrast to leather. Polyurethane polymers such as coatings or impregnating agents for fabrics to provide leather replacement materials have long been recognized. Polyurethanes can be produced, for example, which are highly resistant to solvents and abrasion, imparting to the coated fabrics excellent durability and washability in chemical washing. The basic chemistry of polyurethanes, involving reactions between isocyanate groups and molecules with multiple reactive hydrogen, such as polyols and polyamines, provides great versatility and variability in the final chemical and physical properties through the choice of intermediates to achieve treatability and the desired balance of end-use performance receivables.

There are various methods of applying polyurethane solutions or other post-curable liquid polymers to porous substrates which are well known to those skilled in the art. An article in the Journal of Coated Fabrics, vol. 7 (July 1977), p. 43-57 describe some of the commercial coating systems, such as reverse roller coating, container feeder coating device, engraving and the like.

Brushing and spraying can also be used for coating polyurethanes on porous substrates. These polyurethane solutions are dried or cured after impregnation or coating on the porous substrate by a method such as heated air, infrared radiation and the like. Characteristic of these processes is the deposition of a polymer and a film-like layer, which tends to form a coated fabric, which folds into undesirably sharp folds rather than leather-like grain fractures. Other methods of combining polymeric solutions and especially polyurethane solutions with porous substrates are exemplified in U.S. Pat. No. 3,208,875 and U.S. Pat. No. 3,100,721. An improved process for impregnating fabric is described in U.S. Pat. PS 4 171 391, which comprises certain steps necessary for the formation of imitation, sheet-like leather material.

According to the present invention, there is provided a method of impregnating porous, sheet-like materials and especially needled cotton wool, wherein uniform impregnation is effected in an aqueous system to form a product with high tear strength and integrity.

Furthermore, an impregnated, fibrous web is provided, which has a new and unusual, valuable structure adapted for use in the formed state or subsequently treated to achieve further benefit.

The product according to the invention further forms an imitation, sheet-shaped leather material, which has the appearance and properties of natural leather and furthermore has certain physical similarities therewith.

BRIEF DESCRIPTION OF THE INVENTION The present resin impregnated fibrous web is characterized in that the impregnated web has filaments which are both coated and uncoated with polyacrylate resp. polyurethane, the polyacrylate resp. the polyurethane is present in an added amount of at least 70% by weight and preferably less than 400% by weight, for example 200-300% by weight based on the weight of the fibrous batt.

The present method is characterized in that a needled, fibrous wad is completely saturated with an aqueous dispersion or emulsion of ionically solubilized polyacrylate or ionically solubilized polyurethane, that the fully saturated, needle wadding is contacted with an ionic coagulant for coagulating the polyacrylate. the aqueous dispersion and the deposition of polyacrylate or polyurethane inside the needle pad, after which the needle pad and the polyacrylate or polyurethane are dried in a manner known per se.

DETAILED DESCRIPTION OF THE INVENTION "5-room density" as used herein refers to the density of the material, including air spaces. "Actual density" here refers to the density of the material, including air space, ie. the density (spec. weight).

Suitable substrate fibers in the fibrous batt are natural fibers, especially cotton and wool, synthetic fibers such as polyester, nylon, acrylic, modacrylic and rayon. The fibrous mass is most suitably needled, fibrous batters formed from such natural and synthetic fibers. The fibers preferably have a denier number of 1-5 and a length which is suitable for carding and which is typically 2.5-15 cm, preferably 38-76 mm.

The needled, fibrous pads can have either high, medium or low density. High density pads have a maximum density of 0.5 g / cms. These high density waders are typically composed of wool. When synthetic fibers are used in the formation of the batters, the high density batters have densities up to 0.25 g / cm 2.

In the practice of the invention, fibrous pads preferably have a density of 0.08-0.5 g / cm 3. The thickness of the batters can be up to 8.5 mm and is preferably between 3 and 10 cm with a minimum thickness of 7.5 mm. The pads are also characterized by being "saturating pads" which have high integrity due to the needling treatment in contrast to easily bonded pads with a few needle sticks with little or no integrity.

Polymer resins useful in the practice of the invention are preferably those polymeric resins which are capable of solubilizing, dispersing or emulsifying in water and subsequent coagulation from the aqueous system with an ionic coagulant.

A suitable polymer system is one synthesized from acrylic monomers such as alkyl acrylate and methacrylate, acrylonitrile, methacrylonitrile and other well known acrylic monomers. These acrylic monomers can be polymerized by emulsion polymerization to form a latex or by other free radical polymerization mechanisms and then solubilized or emulsified in water. The emulsification or solubilization system must be such that when the emulsion is contacted with concentrated acid or base, the polymer coagulates. the aqueous system and is made substantially insoluble.

Emulsified or aqueous dispersed polyurethanes were most conveniently used. Examples of emulsified polyurethanes are those described in US-PS Z 968 575, which are prepared and dispersed in water by means of detergents under the influence of strong shear forces. When these polyurethane emulsions are formed, the emulsifier or detergent must be ionic in nature so that a counterion can be added to the aqueous system for coagulating polymers. Polyurethanes which are valuable in the practice of the invention are most suitable. 10 15 25 35 40 7 ~ 452 994 ionically water dispersible.

A suitable system for preparing ionic aqueous polyurethane dispersions is to prepare polymers with free acid groups, preferably carboxylic acid groups which are covalently bonded to the polymer backbone. Neutralization of these carboxyl groups with an amine, preferably a water-soluble monoamine, provides water dilutability. Careful selection of the compound bearing the carboxyl group must be made because isocyanates, which are necessary constituents of any polyurethane system, are generally reactive with carboxyl groups. However, as described in U.S. Pat. No. 3,412,054, which is incorporated herein by reference, 2,2-hydroxymethyl substituted carboxylic acids can be reacted with organic polyisocyanates without significant reaction between acid and isocyanate groups due to the steric barrier to the carboxyl by adjacent alkyl groups. This problem solution yields the desired carboxyl-containing polymer, whereby the carboxyl groups are neutralized with the tertiary monoamine to provide 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 be prepared, for example, from an aldehyde containing at least two hydrogens in the alpha 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 acid by methods known to those skilled in the art. Such acids are illustrated by the structural formula CHZOH R - C -COOH ÉHZOH wherein R represents hydrogen or alkyl of up to 20 carbon atoms, preferably up to 8 carbon atoms. A suitable acid is 2,2-dimethoxymethylpropionic acid. Polymers with pendant carboxyl groups are characterized as anionic polyurethane polymers.

According to the present invention, a further alternative route for achieving water dilutability is to use a cationic polyurethane having pendant amino groups. Such cationic polyurethanes are described in U.S. Pat. No. 4,066,591, which is incorporated herein by reference, and in particular in Example XVII. In the context of the present invention, it is convenient that anionic polyurethane be used. In particular, polyurethanes which are valuable in the practice of the present invention involve the reaction of di- or polyisocyanates and compounds with several reactive hydrogens suitable for the production of polyurethanes. Such diisocyanates and reactive hydrogen compounds are more fully described in U.S. Pat. Nos. 3,412,034 and 4,046,729. Processes for the preparation of such polyurethanes are further well known, as exemplified by the aforementioned patents, According to the present invention, aromatic, aliphatic and cycloaliphatic diisocyanates or mixtures thereof are used in the formation of the polymer, such diisocyanates being, for example, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, m-phenylene diisocyanate, biphenylene-4,4'-diisocyanate, methylene bis (4-phenyl isocyanate), 4-chloro-1,3-phenylene diisocyanate, naphthylene-1,5-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. Preferably, the arylene and cyclealiphatic diisocyanate are most advantageously used in the practice of the invention.

The arylene diisocyanate characteristically comprises those in which the isocyanate group is attached to the aromatic ring.

The most suitable isocyanates are 2,4- and 2,6-isomers of tolylene diisocyanate and mixtures thereof due to their readiness and reactivity. Cycloaliphatic diisocyanates most conveniently used in the practice of the present invention are further 4,4'-methylene 4 (cyclohexylisocyanate) and isophorone diisocyanate.

The selection of the aromatic or aliphatic diisocyanates is determined by the end use of the particular material.

As is well known to those skilled in the art, the aromatic isocyanates can be used where the final product is not excessively exposed to ultraviolet radiation, which tends to yellow such more powdery compositions; while the aliphatic diisocyanates can be used more appropriately outdoors and have less tendency to yellow on 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 by well-known ultraviolet stabilizers to improve the final properties of the polyurethane impregnated sheet material. Antioxidants can also be added at known levels to improve the properties of the final product. Typical antioxidants are thioethers and phenolic antioxidants, such as 4,4'-butylidine-bis-m-cresol and 2,6-di-t-butyl-p-cresol. The isocyanate is reacted with the multiple reactive hydrogen compounds, such as diols, diamines or trioler. In the case of diols or triols, they are typically either polyalkylene ether or polyester polyols. A polyalkylene ether polyol is the suitable active, hydrogen-containing polymeric material for the preparation of the polyurethane. The most useful polyglycols have a molecular weight of 50-10000 and in the context of the present invention it is most suitably about 400-7000. Polyether polyols further improve flexibility in proportion to the increase in their molecular weight.

Examples of polyether polyols are, but are not limited to, polyethylene ether glycol, polypropylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyoctamethylene ether glycol, polydecamethylene ether glycol, polydodecamethylene ether glycol and mixed glycol. Polyglycols containing several different groups in the molecular chain, for example the compound HO (CH2OC3H4O) nH, where n represents a greater integer than 1, can also be used.

The polyol can also be a polyester with end position hydroxy or with hanging hydroxy, which polyester can be used instead of or in combination with the polyalkylene ether glycols. Examples of such polyesters are those formed by the reaction of 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 most suitable when flexibility is desired. These glycols cause: to react with aliphatic, cycloaliphatic or aromatic dicarboxylic acids or lower alkyl esters or ester-forming derivatives to form polymers of relatively low molecular weight, preferably having a melting point lower than about 70 DEG C. and a molecular weight equal to those indicated for the glycolene .

Acids for the preparation of such polyesters are, for example, phthalic acid, maleic acid, succinic acid, adipic acid, suberic acid, sebacic acid, terephthalic acid and hexahydrophthalic acid and alkyl- and halogen-substituted derivatives of these acids. In addition, polycaprolactone with hydraxyl groups in the terminal position can also be used.

A particularly useful polyurethane system is the crosslinked polyurethane system, more fully described in US-SN 947 544, filed October 2, 1978 by Andrea Russiello and entitled "Crosslinked Polyurethane Dispersions", which is incorporated herein by reference.

The term "ionic dispersant" as used herein refers to an ionizable acid or base capable of forming a salt with the solubilizing agent. These "ionic dispersants" are amines and preferably water-soluble amines such as triethylamine, tripropylamine, X-ethylpiperidine and the like; as well as acid and preferably water-soluble acids, such as acetic acid, propionic acid, lactic acid and the like. Of course, the acid or amine will be selected depending on the solubilizing group attached to the polymer chain.

The desired elastomeric appearance would generally require about 25-80 weight percent long chain polyol [i.e., 700-2000 eq weight] in the polymer. The degree of elongation and elasticity can vary widely from product to product depending on the desired properties of the final product.

In the preparation of polyurethanes useful in the practice of the invention, the polyol and molar excess diisocyanate are reacted to form polymer with isocyanate in the final position. Although suitable reaction conditions and reaction times and temperatures are variable within the context of the particular isocyanate and particular polyol used, those skilled in the art will recognize these variations. Such experts recognize that the reactivity of the components in question requires a balance in reaction rate with undesirable secondary reactions leading to staining and molecular weight degradation. Typically, the reaction is carried out with stirring at about 500- about 120 ° C for about 1-4 hours. To produce pendant carboxyl groups, the polymer with isocyanate is brought to the end position to react with a molar deficit of dihydroxy acid for 1-4 hours at 50-IZOOC to form a prepolymer with isocyanate in the end position. The acid is suitably added as a solution, for example in N-methyl-1,2-pyrrolidone or N-N-dimethylformamide. The solvent for the acid will typically be no more than about 5% of the total charge for reducing the concentration of organic solvent in the polyurethane composition. After the dihydroxy acid has reacted into the polymer chain, the pendant carboxyl groups are neutralized. 11 with an amine at about 58-TSOC for about 20 minutes and chain extension and dispersion are performed by addition to water with stirring. A water-soluble diamine can be added to the water as an additional chain extender. The chain extension involves the reaction of the remaining isocyanate groups with water to form urea groups and the further polymerization of the polymeric material with the result that all the isocyanate groups react due to the addition of a large stoichiometric excess water. It should be noted that the polyurethanes of the invention are thermoplastic in nature, i.e. do not have the ability to significantly further cure after formation except by the addition of an external curing agent. Preferably, no such curing agent is added to form the sheet-shaped composite material.

Sufficient water is used to disperse the polyurethane at a concentration of about 10-40% by weight of dry matter and a dispersion viscosity in the range of 10-1000 cP.

The viscosity can be adjusted according to the special, desired impregnation properties and by the special dispersion composition; which is all governed by the end product properties. It should be noted that no emulsifiers or thickeners are required for the stability of the dispersions.

Those skilled in the art will recognize ways to modify the primary polyurethane dispersion according to the end product use, for example by adding colorants, compatible vinyl polymer dispersions, ultraviolet filtration mixtures, stabilizers against oxidation and the like.

The characterization of dispersions prepared according to the invention takes place by measurements of the non-volatile content, particle size, viscosity measurements and by the elongation-stress properties of strips of cast film.

The concentration range useful in the practice of the invention is governed by the desired percentage addition of polymer into the needle wadding.

The dispersion viscosity is generally in the range of 10-1000 cP. The low viscosity relative to that of identical polymers at the same dry matter level in polymer solutions in organic solvent is helpful for rapid and complete penetration of the aqueous dispersion and subsequent penetration of the coagulant. Useful polyurethane solutions, on the other hand, will generally have viscosities of several thousand cP and are as high as 50,000 cP at concentrations of 20-30%.

The polymers should be impregnated into the fibrous wadding at a level of at least 70% by weight of additive, by weight of fibrous wadding, and up to about 400% by weight. Preferably, the polymer resin is impregnated at a level of about 200-300% by weight of additive, based on the weight of fibrous wadding.

Coagulation is accomplished by contacting the impregnated substrate with an aqueous solution of an ionic medium intended to ionically replace the solubilizing ion.

Although the invention is not intended to be bound by any theory, in the case of an anionically solubilized polymer the amine, which neutralizes the carboxyl-containing polyurethane, is replaced with a hydrogen ion, which regenerates the anionic carboxyl ion and thus restores the polymer in its original, "non-dilutable" form. state. This causes coagulation of the polymer in the substrate structure.

In the case of anionic polymer, aqueous acetic acid solutions in concentrations of 0.5- about 75% are suitable ionic coagulants for the anionic dispersions and are more suitable than stronger acids due to the relative ease of handling, low corrosion potential and availability.

"Salting out" for coagulation of the dispersion by the addition of neutral salt is possible, but is not favorable due to the required large amounts of salt, about 10 times the concentration of acid, and associated problems with product contamination.

When impregnating the needle wadding with the polymer resin, as referred to herein, the wadding is immersed in an aqueous, ionic emulsion or dispersion at a concentration level sufficient to effect an addition of at least 70% by weight.

Upon immersion of the batt in the aqueous emulsion or dispersion, the batt may be compressed to remove air to provide full impregnation of the emulsion or dispersion in the batt. The wadding, which is now completely impregnated with the aqueous dispersion or emulsion, is passed through wiping rollers or the like to remove excess dispersion or emulsion on the surface of the impregnated wadding.

The batt is then immersed in a bath containing the motion to effect coagulation, the counterion-containing material penetrating the batt by diffusion and causing coagulation of the resin in the fibrous structure. After coagulation, the batt is pressed to remove excess water and dried to form the impregnated web.

This process is a further improvement on the process described in U.S. Pat. No. 4,171,391 for the manufacture of special products. The differences between the stated patent and the present method are that the wadding is completely saturated, i.e. no air space remains, the aqueous dispersion or emulsion producing a final addition of at least 70% by weight of polymer resin, based on the weight of the batt. Due to these differences, a new structure is obtained, in which the batt has an entirely uniform density and the bulk density of the web is less than the actual density of the web.

After the impregnated web has been formed, it is useful for producing, for example, imitation leather material in sheet form, whereby the web is given a density gradient. The impregnating agent for the web is then preferably polymers which, in particulate form, have the ability to fuse with themselves under heat and pressure conditions. These polymers are normally thermoplastic; however, certain crosslinkable crosslinkable polymers can also be used. In particular, polyurethanes, described in U.S. Patent SN 947,544, filed October 2, 1978 by Andrea Russiello and entitled "Crosslinked Polyurethanes Dispersions", have been found to be particularly useful in achieving the desired density gradient by increasing the thickness of the material. The characteristic feature of the imitation sheet material is mainly physical features, a density gradient being produced 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, this grain layer having an actual density equal to its bulk density.

This grain layer closely mimics the grain layer of natural leather.

On the opposite side of the sheet material there is a surface delimiting the gap layer which has less bulk density than the actual density, there being a preferably uniform density gradient through the material. The gap layer is slightly fibrous and lines the gap layer of natural leather.

The polymer is present in the mimetic, sheet-like leather material at a level of at least 70% by weight of additive based on the weight of the fibrous mass.

The slit layer typically has up to about 75% of the density of the grain layer to produce a porous grain layer, which mimics the grain layer of leather. It must also be noted that the polymer is uniformly distributed throughout the fibrous mass in such a way that the ratio of fiber to polymer is uniform throughout.

The imitation sheet-like leather material is prepared by treating the impregnated fibrous mass and preferably an impregnated, non-woven fabric material, as previously described.

The polymer used as an impregnating agent is most suitably one of them or of the type described in US-SN 947 544, as previously cited.

In one treatment method, the impregnated, nonwoven fabric material, which is to form the imitation leather sheet, is applied in a press and heat and pressure are applied on both sides thereof.

The sleeve and the pressure are sufficient for the polymer to fuse by itself in the impregnating agent at the surfaces of the material, but still insufficient for complete fusion of the polymer in the interior of the fabric material. This process produces a density gradient from the interior of the nonwoven fabric to the two outer surfaces. The thickness dimensions of the heated and pressed fabric material can be controlled by the pressure applied during the heating and pressing treatments, or by inserting spacers between the press plates or by using a press with a resting load.

The press plates can furthermore be in relief for creating a specific surface pattern on the material. After pressing, the sheet material is split in half to create two imitation leather sheets, each having a grain layer and a gap layer.

In another method of forming the mimicked sheet-like leather material, the impregnated nonwoven starting material previously discussed may be applied in a press with only one of the plates heated to form the grain layer, while the opposite side to the cold plate forms the column layer. In yet another method of forming the mimicked sheet material, two pieces of impregnated, nonwoven starting material, as previously discussed, may be applied to each other in a press and heat and pressure is applied sufficiently to fuse the polymer itself to the impregnating agent at the outer surface of each piece.

After pressing, the individual pieces are separated, leading to two sheets of imitation leather.

After formation, the imitation leather can be polished, coated or further treated according to known leather finishing techniques.

In yet another method, the grain layer developing can be accomplished on unwound strips of impregnated, nonwoven starting material that are unwound from packages and passed through a roll pair in a calendering treatment. Preferably, one of the metal rollers is heated to 150-205 ° C and is smooth or provided with suitable relief; and the second roller is of a softer, resilient material, such as rubber.

The grain layer will be developed on the side of the sheet against the metal roller.

Effective calendering can be performed generally with a load of 5.5-16.5 tons / m width of sheets passing through the rollers. Wetting the sheet before calendering to 50-100% by weight of added water can be helpful in calendering.

The structures of the impregnated web and the imitation sheet-like leather material are shown more fully in the accompanying drawings, which are photomicrographs of cross-sections of an impregnated web and an imitation leather material in sheet form.

BRIEF DESCRIPTION OF THE DRAWINGS Pig. 1 shows a plan view of a resin impregnated web prepared according to Example 1 before cleavage; 2 shows a photomicrograph taken through the thickness of 1 along the line III-II; Fig. The web according to fig.

Pig. Fig. 3 shows a 100 x micrograph of section III according to Fig. Z; Fig. 4 shows a 100 x photomicrograph of section IV according to Fig. 2; Fig. 5 shows a 100 X photomicrograph of section V according to Fig. 2; (r: 10 15 25 40 452 994 m Fig. 6 shows a 100 x photomicrograph of a resin impregnated batt prepared according to Example 1 after cleavage and Fig. 7 shows a 100 x photomicrograph of a cross section through the thickness of a mimicked, sheet-like leather material made from the batt of Fig. 6.

DETAILED DESCRIPTION OF THE DRAWINGS In Figures 1-5, where like reference numerals refer to like parts, there is shown a resin impregnated web 10 prepared according to Example 1.

In particular, Figures 2-5 show a cross section through the thickness of the web 20.

The web 10 is composed of an upper surface 12 and a lower surface 14.

Through the web 10 there is a substantial number of uncoated fibers 16, resin concentrations 20, voids 18 and resin coated fibers 22.

The structure and consequently its bulk density is substantially uniform throughout the material thickness, although the structure on a micro-scale is non-homogeneous.

The structure shown in Figures 2-5 is considered to be attributable to the needle wadding with full impregnation with aqueous emulsion or dispersion and subsequent coagulation of the polymer, while the wadding is completely impregnated with the aqueous resin system.

Fig. 6, which shows a 100 x photomicrograph, shows a split, impregnated, needled batting 24 of uniform density throughout, as shown in Figs. 1-S. The impregnated batt Z4 has a substantial amount of uncoated fibers 26, polymer masses 28, coated fibers 32 and voids 30. It should be noted that although the impregnated batt is non-homogeneous on a microscale, it has a uniform bulk density throughout.

Fig. 7, which shows a 100 X photomicrograph, shows the imitated sheet material 32 of Example 4.

The material 32 has a grain layer 54 which has a minimum void space and the bulk density at the grain layer 34 is equal to the actual density. At the grain layer 34, a composite 36 of fibers is formed in a continuous resin fl round mass due to the application of heat and pressure. When moving in the direction A, it is shown that the cavities 30 increase along the direction approaching the gap layer 38. At the gap layer 38 there are a significant number of cavities 30, uncoated fibers 26 and polymer masses 28. The structure at the gap layer 38 approaches the structure shown in Fig. 6.

The following examples illustrate products made in accordance with the invention.

EXAMPLE * 1 A needle wadding which was thermoset and had a density of 1200 g / m 2 consisted of polyester, polypropylene and rayon fibers and had a thickness of 7.6 mm with a bulk density of 0.16 g / cns was immersed in a polyurethane prepared according to Example III of US-SN 947 544 in the name of Andrea Russiello, previously cited herein.

The polymer dispersion had a total content of 22% dry matter to give an addition of 120%, based on the weight of the batt.

The batt was immersed in the polyurethane dispersion for 10 minutes. at room temperature, until all the air has been expelled from the batting and the batting was completely impregnated. The surface of the wadding was wiped with a straight edge on both sides to remove excess aqueous dispersion and immersed in a bath of 10% acetic acid for 10 minutes. at room temperature. The immersion in the acid completely coagulated the polyurethane in the fiber structure. Excess acetic acid was washed from the batt and the resin-impregnated batt was pressed to remove excess water. The resin-impregnated batt was split into four slices by its thickness and each split product was dried at 150-17 ° C in a circulating air oven to form four resin-impregnated webs with a bulk density of 0.45 g / cm 2. The end product had an appearance that can be seen from the micrograph in the drawings.

EXAMPLE 2 Example 1 was repeated except that a batt of 100% polyester having a density of 0.13 g / cm 3 and a thickness of 5.0 mm was impregnated with a dispersion of 22% dry matter according to Example 1. The resulting impregnated web had throughout a uniform density, high integrity and a bulk density of 0.38 g / cm °.

EXAMPLE 3 Example 1 was repeated except that a needle pad of 100% polyester with a thickness of 5.6 mm and a density of 0.25 g / cm 2 was impregnated with a dispersion of 52% dry matter to form a needled, resin-impregnated fibrous web with a bulk density of 0.56 g / cm 2. The product of Example 3 was used as a polishing pad and had strength, high tear strength, elasticity and complete recovery upon compression. The method and product of the present invention thus provide an impregnated fibrous web with high integrity and useful as a product per se and valuable time formation of other products. The impregnated fibrous web can be further polished to provide a desired surface.

EXAMPLE 4 Two 1.8 mm thick slits of the nonwoven impregnated web prepared according to Example 1 were superimposed and placed between the plates in a press heated to 150 DEG C. at a pressure of 3.5 MPa for 30 seconds. The two gap products were then separated, thus obtaining two sheets of imitation, sheet-like leather material. The grain layer in the sheets corresponds to the surfaces that were in contact with the hot press plates. The inner sides of the sheet retained their fibrous texture similar to the unpressed sheet. Microscopic examination showed that the mimicked sheet material had a density gradient from the grain layer to the slit layer, as shown in Fig. 7.

The imitation, sheet-shaped leather material can be post-formed with other polymers for surface treatment according to the prior art.

Although the invention has been described with reference to particular materials and methods, the invention is limited only to the extent set forth in the claims.

Claims (11)

452,994 19 Patent claims A resin impregnated fibrous web comprising: a nalad, fibrous batt, a polyacrylate or a polyurethane distributed in the batt to form a resin impregnated fibrous web, the density of the impregnated fibrous web being uniformly uniform, and the bulk density of the web is smaller than the actual density of the web, as the web is porous, characterized in that the impregnated web has filaments which are both coated and uncoated with polyacrylate resp. polyurethane, the polyacrylate resp. the polyurethane is present in an added amount of at least 70% by weight and preferably less than 400% by weight, for example 200-300% by weight based on the weight of the fibrous batt. 2. A web according to claim 1, characterized in that the needled, fibrous batt has a lower bulk density than 0.5 g / cm 3, e.g. lower than 0.25 g / cm3, or for example between 0.12 and 0.4 g / am3. 3. A web according to claim 1 or 2, characterized in that the needled, fibrous batt has a thickness of at least 0.75 mm. 4. A web according to any one of claims 1-3, characterized in that the needled, fibrous batt is composed of substantially non-fusible fibers. 5. A web according to any one of claims 1 to 4, characterized in that the polyurethane is a water-dispersible polyurethane or a crosslinked polyurethane. A web according to any one of claims 1-5, characterized by a density of up to about 0.75 g / cm 2, e.g. about 0.4 - about 0.75 g / cm3. 7. A method of forming a resin-impregnated fibrous web, characterized in that a needled, fibrous wadding is completely saturated with an aqueous dispersion or emulsion of ionically solubilized polyacrylate or ionically solubilized polyurethane, that the fully saturated needled needle is brought contact with an ionic coagulant for coagulating the polyacrylate or polyurethane from the aqueous dispersion and depositing polyacrylate or polyurethane inside the needle pad, after which the needle pad and the polyacrylate or polyurethane are known per se. way. 8. A method according to claim 7, characterized in that the needled wadding has a lower bulk density than 0.5 g / cm 3, e.g. lower than 0.25 g / cm 3, or preferably between 0.12 and 0.4 g / cm 3, the needled fibrous batt preferably having a thickness of at least 0.75 mm and preferably consisting of non-fusible fibers. 9. A method according to claim 7 or 8, characterized in that the polyurethane is, for example, a crosslinked polyurethane and that it is preferably present in the web in an amount of at least 70% by weight and preferably less than 400% by weight, for example 200-300% by weight. additive, based on the weight of the fibrous wadding. 10. A method according to any one of claims 7-9, characterized in that the aqueous dispersion or emulsion used has a dry matter content of 5-60% by weight. 11. A method according to any one of claims 7-10, characterized in that the impregnated fibrous web has a density of up to 0.75 g / cm 3, e.g. between 0.4 and 0.75 g / cm 3.