KR20260040157A - Artificial leather, its manufacturing method, and its uses - Google Patents

Abstract

Artificial leather comprising a fibrous substrate formed by the intertwining and integration of a nonwoven fabric and a fabric, and a polyurethane having hydrophilic groups, wherein the nonwoven fabric is composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 10.0 μm or less, the fabric is composed of multifilaments having a number of filaments of 30 or more and 300 or less, and the average single fiber diameter of the filaments constituting the multifilament is 1 μm or more and 30 μm or less, the polyurethane content ratio in the artificial leather is 15 mass% or more and 25 mass% or less, and the ratio of filaments to which the polyurethane is attached among the outermost filaments of the multifilament is 10% or more and 80% or less.
Artificial leather comprising a fibrous substrate in which nonwoven fabric and fabric are interwoven and integrated, and a water-dispersible polyurethane, has high strength, excellent flexibility, and abrasion resistance, and the artificial leather, the method of manufacturing the same, and the use thereof are provided.

Description

Artificial leather, its manufacturing method, and its uses

The present invention relates to artificial leather, a method for manufacturing the same, and uses thereof.

Artificial leather, primarily composed of fibrous substrates such as non-woven fabrics and polyurethane, possesses superior characteristics not found in natural leather, such as high durability and uniformity. In particular, so-called suede-like artificial leather, in which the surface is buffed to form fine fibers, is used in various fields, including not only medical materials but also automotive interior materials, furniture interior materials, and construction materials. Notably, instead of using conventional organic solvent-based polyurethane, the method of using water-dispersible polyurethane, in which polyurethane resin is dispersed in water, is being widely considered from an environmental perspective.

When suede-like artificial leather is used as a surface material for vehicle interiors, etc., deformation may occur in the surface material due to repeated use over a long period. Therefore, a method is being considered to produce artificial leather that is high-strength and can withstand long-term use by integrating a fabric into the inside or on one side of the nonwoven fabric.

However, artificial leather that integrates fabric into the interior or on one side of a nonwoven fabric generally has the problem of being prone to becoming hard to the touch. One of the main reasons for this is that the applied polyurethane strongly grips the entanglement points of the fabric, thereby reducing the fabric's degree of freedom.

In particular, when a water-dispersible polyurethane is used as the polyurethane and solidified by coagulating the polyurethane emulsions together by heating, the polyurethane film structure becomes a dense, non-porous film, so the adhesion between the fabric and the polyurethane becomes dense, and the interlocked parts of the fibers constituting the fabric are strongly gripped, making the texture significantly firmer.

In light of these circumstances, several methods have been proposed to obtain artificial leather with high strength and excellent flexibility by applying water-dispersible polyurethane to artificial leather in which a fabric is interwoven and integrated inside or on one side of a nonwoven fabric.

For example, Patent Documents 1 and 2 propose a method in which a specific amount of polyvinyl alcohol with a specific degree of saponification and polymerization is applied to a fibrous substrate, followed by the application of a water-dispersible polyurethane, and then the polyvinyl alcohol is removed. Furthermore, it is stated that according to this method, an elegant and beautiful appearance and a flexible texture can be achieved, and a sheet-like material having additionally good wear resistance can be obtained.

In addition, Patent Document 3 states that by setting the ratio of polyurethane resin to 100 mass% of fiber sheet to 20 mass% or less, a flexible texture can be achieved even in artificial leather containing a woven or knitted scrim and using a water-dispersible polyurethane resin.

Japanese Patent Publication No. 2013-234409 International Publication No. 2014/042241 International Publication No. 2020/054256

In the method disclosed in Patent Documents 1 and 2, polyvinyl alcohol applied before applying polyurethane coats the woven fabric and is removed after applying polyurethane, thereby preventing direct adhesion between the polyurethane and the woven fabric and achieving a flexible texture; however, since it requires a polyvinyl alcohol elution treatment, there is room for improvement in terms of manufacturing efficiency.

In the method disclosed in Patent Document 3, since the amount of polyurethane applied is small, it is difficult to say that it satisfies the level required by the market in terms of wear resistance.

Therefore, the objective of the present invention is to provide an artificial leather comprising a fiber entanglement made of nonwoven fabric and fabric as a component, in consideration of the above problem, which is manufactured using an environmentally friendly process that does not use organic solvents, and which combines a flexible texture and excellent wear resistance, and a method for manufacturing the same.

To solve the above problem, the present invention has the following configuration. That is,

[1] An artificial leather made of a fibrous substrate formed by the intertwining of a nonwoven fabric and a fabric, and a polyurethane having hydrophilic groups,

The above nonwoven fabric is composed of polyester ultrafine fibers having an average staple fiber diameter of 0.1㎛ or more and 10.0㎛ or less, and

The above fabric is composed of multifilaments having a number of filaments ranging from 30 to 300, and additionally, the average staple fiber diameter of the filaments constituting the multifilaments is 1㎛ or more and 30㎛ or less, and

The content ratio of the polyurethane in the above artificial leather is 15 mass% or more and 25 mass% or less, and

In addition, artificial leather in which the ratio of the filaments to which the polyurethane is attached among the outermost filaments of the above multifilament is 10% or more and 80% or less.

[2] Artificial leather described in [1], wherein the above polyurethane is a polyether-based polyurethane and/or a polycarbonate-based polyurethane.

[3] A method for manufacturing artificial leather as described in [1], comprising the following steps (1) to (3) in this order.

(1) A process of forming a fibrous substrate by entangling and integrating a nonwoven fabric made of ultrafine fiber-expressing fibers and a fabric.

(2) A process of obtaining a shrink sheet having a width of 0.85L or more and 0.95L or less, wherein the width of the fibrous substrate before impregnation is L, with respect to the sheet obtained by impregnating the fibrous substrate with an aqueous dispersion of a polyurethane having hydrophilic groups and then solidifying the polyurethane.

(3) A process for developing polyester microfibers from the microfiber-developing fibers of the above shrink sheet.

[4] A method for manufacturing artificial leather described in [3], wherein the means of entanglement integration in the above process (1) is needle punch processing.

[5] A method for manufacturing artificial leather as described in [3] or [4], wherein the means for obtaining the shrink sheet in the above process (2) is a dry heat treatment at an atmosphere temperature of 100°C or higher and 180°C or lower.

[6] A method for manufacturing artificial leather described in any one of [3] to [5], wherein the means of producing the polyester ultrafine fiber in the above process (3) is alkali treatment.

[7] Automotive interior material comprising artificial leather as described in [1] or [2].

[8] An automotive part comprising artificial leather as described in [1] or [2].

[9] A seat comprising artificial leather as described in [1] or [2].

According to the present invention, in an artificial leather composed of a fibrous substrate in which a nonwoven fabric and a fabric are intertwined and integrated, and a water-dispersible polyurethane, an artificial leather having high strength, excellent flexibility, and abrasion resistance can be obtained through a simple process.

Figure 1 is a schematic cross-sectional view of a scanning electron microscope (SEM) image of a cross-section of artificial leather taken to measure and calculate the ratio of filaments to which polyurethane is attached among the filaments of the outermost periphery of the multifilament.

The artificial leather of the present invention is an artificial leather comprising a fibrous substrate formed by the intertwining and integration of a nonwoven fabric and a fabric, and a polyurethane having hydrophilic groups.

The above nonwoven fabric is composed of polyester ultrafine fibers having an average staple fiber diameter of 0.1㎛ or more and 10.0㎛ or less, and

The above fabric is composed of multifilaments having a number of filaments ranging from 30 to 300, and additionally, the average staple fiber diameter of the filaments constituting the multifilaments is 1㎛ or more and 30㎛ or less, and

The content ratio of the polyurethane in the above artificial leather is 15 mass% or more and 25 mass% or less, and

In addition, among the filaments of the outermost periphery of the above multifilament, the ratio of the filament to which the polyurethane is attached is 10% or more and 80% or less.

Although this component is described in detail below, the present invention is not limited in any way to the scope described below, as long as it does not exceed the gist thereof, and various modifications are possible within the scope that does not deviate from the gist of the present invention.

[Polyester microfiber]

The artificial leather of the present invention is composed of a fibrous substrate, which is one of the components, made of polyester ultrafine fibers having an average staple fiber diameter of 0.1 μm or more and 10.0 μm or less. In addition, "polyester ultrafine fiber" refers to the "ultrafine fiber made of a polyester-based resin" described below, and "ultrafine fiber" refers to a fiber having a staple fiber diameter of "0.1 μm or more and 10.0 μm or less" measured and calculated by the method described below.

In addition, in the present invention, "polyester-based resin" refers to a resin in which the mole fraction of the polyester unit in the repeating unit is 80 mol% to 100 mol%. Unless otherwise specified, the description "...-based resin" is used. This polyester-based resin can be used to make artificial leather with excellent heat resistance, light resistance, etc. Specific examples include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, mixtures of these polyester resins, or copolymers of these polyesters. The polyester-based resin can be obtained, for example, from a dicarboxylic acid and/or its ester-forming derivative and a diol.

Examples of dicarboxylic acids and/or their ester-forming derivatives used in the above-mentioned polyester resins include terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, and their ester-forming derivatives. Furthermore, the ester-forming derivatives referred to in the present invention include lower alkyl esters of dicarboxylic acids, acid anhydrides, acyl chlorides, etc. Specifically, methyl esters, ethyl esters, hydroxyethyl esters, etc. are preferably used. A more preferred form of the dicarboxylic acid and/or its ester-forming derivative used in the present invention is terephthalic acid and/or its dimethyl ester.

Examples of diols used in the above polyester resin include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and cyclohexanedimethanol. Among these, ethylene glycol is preferably used.

In addition, the above polyester resin may contain inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, UV absorbers, conductive agents, heat storage agents, and antibacterial agents, depending on various purposes.

Both circular and irregular cross-sections can be adopted as cross-sectional shapes for polyester microfibers. Specific examples of irregular cross-sections include polygons such as elliptical, flat, and triangular shapes, as well as fan-shaped and cross-shaped shapes.

In the present invention, the average staple fiber diameter of the polyester microfiber is 0.1 μm or more and 10.0 μm or less. By having the average staple fiber diameter of the polyester microfiber 10.0 μm or less, preferably 7.0 μm or less, and more preferably 5.0 μm or less, the artificial leather can be made more flexible. In addition, the quality of the nap can be improved. Meanwhile, by having the average staple fiber diameter of the polyester microfiber 0.1 μm or more, preferably 0.3 μm or more, and more preferably 0.7 μm or more, the artificial leather can be made to have excellent color development after dyeing when dyeing is performed. In addition, when performing napping treatment by buffing, the ease of dispersion and the ease of disassembly of the polyester microfiber existing in a bundle can be improved.

In addition, the staple fiber diameter and average staple fiber diameter of the polyester ultrafine fiber referred to in the present invention are measured and calculated by the following method. That is,

(1) The cross-section of the obtained artificial leather cut in the thickness direction is observed using a scanning electron microscope (SEM, Keyence Corporation “VHX-D500/D510” or a scanning electron microscope with equivalent performance).

(2) The fiber diameters of 50 randomly selected polyester microfibers within the observation surface are measured in three directions on the cross-section of each polyester microfiber. However, if a polyester microfiber with a different cross-section is used, the cross-sectional area of the single fiber is measured first, and the diameter of the circle corresponding to the cross-sectional area is calculated using the following formula. The diameter obtained from this is taken as the single fiber diameter of that single fiber.

Single fiber diameter (㎛) = (4 × (cross-sectional area of single fiber ( ^㎛² )) / π) ^1/2

(3) Calculate the arithmetic mean value (㎛) of the total of 150 points obtained, round to the second decimal place, and use this as the average single fiber diameter (㎛) of the polyester ultrafine fiber.

[textile]

It is important that the fabric used in the artificial leather of the present invention is composed of multifilaments. As the component constituting the multifilaments, polyester resins or polyamide resins may be used, but it is preferable to use polyester resins that have excellent durability and heat resistance.

It is important that the average single fiber diameter of the filaments constituting the above multifilament is 1 μm or more and 30 μm or less. By making the average single fiber diameter 30.0 μm or less, more preferably 15.0 μm or less, and even more preferably 13.0 μm or less, the artificial leather has excellent flexibility. Meanwhile, by making the average single fiber diameter 1.0 μm or more, more preferably 8.0 μm or more, and even more preferably 9.0 μm or more, the shape stability of the product as artificial leather is improved.

In the present invention, the average single fiber diameter of the filaments constituting the multifilament is calculated by taking a scanning electron microscope (SEM) image of the cross-section of the artificial leather, randomly selecting 10 filaments among the multifilaments constituting the fabric, measuring the single fiber diameters of the filaments, calculating the arithmetic mean of the 10 values, and rounding to the second decimal place. However, in the case where a filament with a different cross-section is used, the diameter of the filament (μm) is obtained by first measuring the cross-sectional area ( ^μm² ) of the filament, and calculating the diameter when the cross-section is considered as a circle, i.e., the diameter equivalent to a circle, in the same way as the measurement and calculation of the average single fiber diameter of the ultrafine fibers constituting the nonwoven fabric.

It is important that the number of staple fibers included in the multifilaments constituting the fabric, i.e., the number of filaments, be between 30 and 300. It is desirable to set the number of filaments to 30 or more, more preferably 50 or more, as this not only improves the shape stability of the product as artificial leather but also makes it difficult for the fibers constituting the fabric to be exposed on the surface of the artificial leather when the nonwoven fabric and the fabric are entangled and integrated using a needle punch or the like. On the other hand, by setting the number of filaments to 300 or less, more preferably 250 or less, and even more preferably 100 or less, the artificial leather becomes highly flexible. At this time, the number of warp filaments and the number of weft filaments may be the same or different.

In addition, it is preferable to set the tensile strength of the multifilament to 1,000 to 4,000 T/m. By setting the tensile strength to 4,000 T/m or less, more preferably 3,500 T/m or less, and even more preferably 3,000 T/m or less, an artificial leather with excellent flexibility is obtained. By setting the tensile strength to 1,000 T/m or more, more preferably 1,500 T/m or more, and even more preferably 2,000 T/m or more, damage to the fibers constituting the fabric can be prevented when the nonwoven fabric and the fabric are entangled and integrated using a needle punch or the like, so that the mechanical strength of the artificial leather becomes excellent.

For the basic weave of the fabric, twill or satin may be used, but a plain weave, which is less prone to weave misalignment, may be preferably used.

In artificial leather, it is desirable to adjust the weave density of the fabric so that both the warp and weft threads are 40 threads/2.54 cm to 200 threads/2.54 cm. By setting the weave density of the fabric constituting the artificial leather to 40 threads/2.54 cm or more, and more preferably 60 threads/2.54 cm or less, an artificial leather with excellent shape stability can be obtained. On the other hand, by setting the weave density of the fabric constituting the artificial leather to 200 threads/2.54 cm or less, and more preferably 150 threads/2.54 cm or less, the texture of the artificial leather can be made flexible, and when the nonwoven fabric and the fabric are interwoven and integrated, there is no hindrance to the intertwining of the fibers of the nonwoven fabric, and as a result, the shedding of fibers in the artificial leather can be suppressed.

[Fiber content]

The fibrous substrate used in the present invention is formed by the intertwining and integration of a nonwoven fabric made of the above-mentioned polyester ultrafine fibers and the above-mentioned fabric.

[Polyurethane having hydrophilic groups]

Next, the artificial leather of the present invention comprises a polyurethane having hydrophilic groups as a component. Further details regarding this will be explained below.

(1) Polyurethane having hydrophilic groups

First, in the present invention, "having a hydrophilic group" refers to having a "group having active hydrogen" itself, and specific examples of the group having active hydrogen include a hydroxyl group, a carboxyl group, a sulfonic acid group, an amino group, etc., and from the perspective of reactivity with the crosslinking agent having a carbodiimide group described later, it is preferable to have a hydroxyl group or a carboxyl group.

This polyurethane having hydrophilic groups is obtained by reacting a polymer polyol described later with an organic diisocyanate and a compound containing an active hydrogen component having hydrophilic groups to form a hydrophilic prepolymer, and then reacting a chain elongator to obtain a polyurethane precursor, to which a crosslinking agent is reacted. Details regarding these are explained below.

(1-1) Polymer polyol

Polymeric polyols preferably used in the synthesis of the above polyurethane include polyether-based polyols, polyester-based polyols, polycarbonate-based polyols, etc.

First, polyether-based polyols include polyols obtained by adding and polymerizing monomers such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin, and cyclohexylene using a polyhydric alcohol or polyamine as an initiator, and polyols obtained by ring-opening polymerization of the above monomers using a proton acid, a Lewis acid, and a cationic catalyst as a catalyst. Specifically, examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc., and copolymer polyols formed by combining these.

Next, polyester-based polyols include polyester polyols obtained by condensing various low molecular weight polyols with polybasic acids, or polyols obtained by polymerizing lactones.

Examples of low molecular weight polyols used in polyester-based polyols include one or more selected from straight-chain alkylene glycols such as “ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol”, branched alkylene glycols such as “neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-methyl-1,8-octanediol”, alicyclic diols such as 1,4-cyclohexanediol, and aromatic dihydric alcohols such as 1,4-bis(β-hydroxyethoxy)benzene. In addition, adducts obtained by adding various alkylene oxides to bisphenol A can also be used as low molecular weight polyols.

Meanwhile, polybasic acids used in polyester-based polyols may include, for example, one or more selected from the group consisting of succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, souveric acid, azelaic acid, sebacic acid, dodecane dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydroisophthalic acid.

In addition, polycarbonate-based polyols may include compounds obtained by the reaction of a polyol and a carbonate compound, such as a polyol and a dialkyl carbonate or a polyol and a diaryl carbonate.

As the polyol used in polycarbonate-based polyols, low molecular weight polyols used in polyester-based polyols can be used. Meanwhile, as the dialkyl carbonate, dimethyl carbonate or diethyl carbonate can be used, and as the diaryl carbonate, diphenyl carbonate can be used.

In addition, the number average molecular weight of the polymer polyol preferably used in the present invention is preferably 500 or more and 5,000 or less. By making the number average molecular weight of the polymer polyol 500 or more, more preferably 1,500 or more, it is easier to prevent the artificial leather from becoming hard to the touch. In addition, by making the number average molecular weight 5,000 or less, more preferably 4,000 or less, it is easier to maintain the strength of the polyurethane having hydrophilic groups as a binder.

(1-2) Organic diisocyanates

Organic diisocyanates preferably used in the synthesis of the above polyurethane include aromatic diisocyanates having a carbon number (excluding carbon in the NCO group, as follows) of 6 or more and 20 or less, aliphatic diisocyanates having a carbon number of 2 or more and 18 or less, alicyclic diisocyanates having a carbon number of 4 or more and 15 or less, aromatic diisocyanates having a carbon number of 8 or more and 15 or less, modified versions of these diisocyanates (carbodiimide modified versions, urethane modified versions, urethdione modified versions, etc.), and mixtures of two or more of these.

Specific examples of the above aromatic diisocyanates having 6 to 20 carbon atoms include 1,3-and/or 1,4-phenylene diisocyanate, 2,4-and/2,6-tolylene diisocyanate, 2,4'-and/or 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, and 1,5-naphthylene diisocyanate, and among these, it is preferable to use MDI, which has excellent flexibility when made into a polyurethane having hydrophilic groups.

Specific examples of the above-mentioned aliphatic diisocyanates having 2 to 18 carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, bis(2-isocyanatoethyl)carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexaate.

Specific examples of the above-mentioned alicyclic diisocyanates having 4 to 15 carbon atoms include isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexylene-1,2-dicarboxylate, and 2,5- and/or 2,6-norbornane diisocyanate, and among these, it is preferable to use dicyclohexylmethane-4,4'-diisocyanate, which has excellent durability when made into a polyurethane having hydrophilic groups.

Specific examples of the above aromatic diisocyanates having 8 or more and 15 or fewer carbon atoms include m- and/or p-xylylene diisocyanates and α,α,α',α'-tetramethylxylylene diisocyanates.

(1-3) Compounds containing active hydrogen components having hydrophilic groups

Examples of compounds containing active hydrogen components having hydrophilic groups that are preferably used in the synthesis of the above-mentioned polyurethane include compounds containing nonionic groups and/or anionic groups and/or cationic groups and active hydrogen. These compounds containing active hydrogen components can be used even in the state of a salt neutralized by a neutralizing agent. By using this compound containing an active hydrogen component having hydrophilic groups, the stability of the aqueous dispersion used in the method of manufacturing artificial leather can be increased.

Examples of compounds having nonionic groups and active hydrogen include compounds having two or more active hydrogen components or two or more isocyanate groups and having polyoxyethylene glycol groups with a molecular weight of 250 to 9,000 in the side chain, and triols such as trimethylolpropane or trimethylolbutane.

Examples of compounds having anionic groups and active hydrogen include carboxyl group-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2-dimethylolvaleric acid, and their derivatives, compounds containing sulfonic acid groups such as 1,3-phenylenediamine-4,6-disulfonic acid and 3-(2,3-dihydroxypropoxy)-1-propanesulfonic acid, and their derivatives, and salts obtained by neutralizing these compounds with a neutralizing agent.

Examples of compounds containing cationic groups and active hydrogen include tertiary amino group-containing compounds such as 3-dimethylaminopropanol, N-methyldiethanolamine, and N-propyldiethanolamine, and their derivatives.

(1-4) Chain extension agent

Examples of chain elongators preferably used in the synthesis of the above polyurethane include water, low molecular weight diols such as ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol and neopentyl glycol, alicyclic diols such as 1,4-bis(hydroxymethyl)cyclohexane, aromatic diols such as 1,4-bis(hydroxyethyl)benzene, aliphatic diamines such as ethylenediamine, alicyclic diamines such as isophoronediamine, aromatic diamines such as 4,4-diaminodiphenylmethane, aromatic diamines such as xylenediamine, alkanolamines such as ethanolamine, dihydrazides such as hydrazine and adipic acid dihydrazide, and mixtures of two or more of these.

Among these, preferred chain extenders are water, low molecular weight diols, and aromatic diamines, and more preferably, water, ethylene glycol, 1,4-butanediol, 4,4'-diaminodiphenylmethane, and mixtures of two or more of these.

(1-5) Composition of polyurethane precursors

As described above, the polyurethane precursor preferably used in the synthesis of the above polyurethane is prepared by reacting the above polymer polyol, an organic diisocyanate, and a compound containing an active hydrogen component having a hydrophilic group to form a hydrophilic prepolymer, and then adding and reacting a chain elongator.

(1-6) Crosslinking agent

As a crosslinking agent preferably used in the synthesis of the above polyurethane, a molecule having two or more reactive groups capable of reacting with reactive groups introduced into the polyurethane precursor may be used. Specifically, examples include polyisocyanate-based crosslinking agents such as water-soluble isocyanate compounds or block isocyanate compounds, melamine-based crosslinking agents, and carbodiimide-based crosslinking agents. One type of crosslinking agent may be used alone, or two or more types may be used in combination.

Water-soluble isocyanate compounds are those having two or more isocyanate groups within a molecule, and examples include the above-mentioned organic polyisocyanate-containing compounds. Examples of commercially available products include the "Bayhydur" (registered trademark) series and "Desmodur" (registered trademark) series manufactured by Bayer Material Science LLC.

Blocked isocyanate compounds are those having two or more blocked isocyanate groups within the molecule. A blocked isocyanate group refers to an organic polyisocyanate compound that has been blocked by a blocking agent such as amines, phenols, imines, mercaptans, pyrazols, oximes, or active methylenes. Examples of these commercially available products include the "Elastron" (registered trademark) series from DKS Co. Ltd., the "Duranate" (registered trademark) series from Asahi Kasei Corporation, and the "Takenate" (registered trademark) series from Mitsui Chemicals, Inc.

Examples of oxazoline-based crosslinking agents include compounds having two or more oxazoline groups (oxazoline backbones) within the molecule. Examples of commercially available products include the "Epocros" (registered trademark) series manufactured by Nippon Shokubai Co., Ltd.

Examples of carbodiimide-based crosslinking agents include compounds having two or more carbodiimide groups within the molecule. Examples of commercially available products include the "Carbodilite" (registered trademark) series manufactured by Nisshinbo Chemical Inc.

Among these, it is particularly desirable to use a carbodiimide compound, which has particularly excellent durability and flexibility of the polyurethane having hydrophilic groups obtained after the reaction.

(1-7) Composition of polyurethane having hydrophilic groups

The polyurethane having hydrophilic groups is preferably a polyether-based polyurethane comprising a component derived from a polyether-based polyol and/or a polycarbonate-based polyurethane comprising a component derived from a polycarbonate-based polyol.

In terms of flexibility, it is desirable to include components derived from polyether-based polyols. Since the polyurethane having hydrophilic groups includes components derived from polyether-based polyols, the degree of freedom of the ether bonds is high, so the glass transition temperature is low and the cohesive force is also weak, so it can be made into a water-dispersible polyurethane with excellent flexibility.

Meanwhile, from the perspective of durability, it is desirable to include components derived from polycarbonate-based polyols. By including components derived from polycarbonate-based polyols, a polyurethane having hydrophilic groups can be produced that exhibits excellent water resistance, heat resistance, weather resistance, and mechanical properties due to the high cohesive force of the carbonate groups.

The composition of the polyurethane having hydrophilic groups can be appropriately adjusted according to the required characteristics, so that a polyether-based polyurethane containing components derived from polyether-based polyols or a polycarbonate-based polyurethane containing components derived from polycarbonate-based polyols may be used alone or both may be used.

In addition, as a method to identify the components of a polyurethane having hydrophilic groups (identifying that the polyurethane having hydrophilic groups includes components derived from polyester polyols, and that the polyurethane having hydrophilic groups further includes components derived from polycarbonate polyols), the polyester constituting the artificial leather is eluted, and for the insoluble material (polyurethane having hydrophilic groups), infrared spectroscopic analysis (using an analytical instrument such as the "FT/IR 4000 Series" manufactured by JASCO Corporation or an infrared spectroscopic analyzer with equivalent performance) and pyrolysis GC/MS analysis (using an analytical instrument such as the "GCMS-QP5050A" manufactured by Shimadzu Corporation or a pyrolysis GC/MS analyzer with equivalent performance) can be performed. In addition, m-cresol or hexafluoroisopropanol can be used as a solvent capable of leaching the polyester constituting the artificial leather, but it is preferable to use hexafluoroisopropanol, which can be handled at room temperature.

In addition, the polyurethane having hydrophilic groups used in the present invention preferably has N-acylurea bonds and/or isourea bonds. The N-acylurea bonds and/or isourea bonds are formed by the reaction of the above-mentioned hydrophilic groups with a crosslinking agent having carbodiimide groups, and by forming a crosslinked structure within the polyurethane having hydrophilic groups, the durability of the polyurethane having hydrophilic groups can be improved.

In addition, the presence of the above-mentioned N-acylurea group or isourea group in a polyurethane having a hydrophilic group can be analyzed by performing mapping processing, such as time-of-flight secondary ion mass spectrometry (TOF-SIMS analysis), on a cross-section of artificial leather (as an analyzer, for example, ION-TOF’s “TOF.SIMS 5” or a TOF-SIMS analyzer with equivalent performance) or infrared spectroscopic analysis (as an analyzer, for example, JASCO Corporation’s “FT/IR 4000 series” or an infrared spectroscopic analyzer with equivalent performance).

[Artificial Leather]

First, the artificial leather of the present invention has a polyurethane content of 15 mass% or more and 25 mass% or less having hydrophilic groups. By making the content 15 mass% or more, preferably 18 mass% or more, it becomes an artificial leather with excellent wear resistance. On the other hand, by making the content 25 mass% or less, preferably 22 mass% or less, it can be made into an artificial leather with a flexible texture.

In the present invention, the content ratio of polyurethane having hydrophilic groups is measured and calculated by the following method. That is,

(1) Cut a 5 cm × 5 cm test piece from artificial leather and measure the mass (M _X ) of the test piece.

(2) Polyester ultrafine fibers are extracted from artificial leather by immersing the test specimen in hexafluoroisopropanol.

(3) After drying the insoluble component (polyurethane having hydrophilic groups) of (2) in a 100°C dryer and measuring the mass (M _A ) of the polyurethane having hydrophilic groups, the content ratio (mass%) of the polyurethane having hydrophilic groups is calculated using the following formula.

Content ratio of polyurethane having hydrophilic groups = (M _A / M _X ) × 100.

In the present invention, it is important that polyurethane is attached to 10% or more and 80% or less of the filaments at the outermost periphery of the multifilament constituting the fabric.

By attaching polyurethane to at least 10%, more preferably at least 15%, and even more preferably at least 20% of the outermost filaments of the multifilament, an artificial leather with excellent shape stability is produced.

Meanwhile, polyurethane is attached to 80% or less, more preferably 60% or less, and even more preferably 50% or less of the outermost filaments of the multifilament, thereby making it an artificial leather with excellent flexibility.

In the present invention, the ratio of filaments to which polyurethane is attached among the filaments at the outermost circumference of the multifilament is measured and calculated by the following method. That is,

(1) A scanning electron microscope (SEM) image of the cross-section of the artificial leather is taken, and the number of filaments (N _M ) at the outermost edge of the multifilament constituting the fabric is calculated, and the number of filaments (N _p ) at the outermost edge of the multifilament that have polyurethane attached is calculated, and the ratio of filaments with polyurethane attached is calculated using the following formula.

Percentage of filaments with attached polyurethane (%) = (N _p / N _M ) × 100

(2) The measurement of (1) is performed on 20 multifilaments, and the average value is used as the ratio of filaments to which polyurethane is attached.

It is preferable that the apparent density of the artificial leather of the present invention be 0.30 g/cm³ or higher and 0.40 g/cm³ or lower. By making the apparent density of the artificial leather 0.30 g/cm³ or higher, more preferably 0.32 g/cm³ or higher, and even more preferably 0.34 g/cm³ or higher, the abrasion resistance of the artificial leather becomes excellent. On the other hand, by making the apparent density 0.40 g/cm³ or lower, preferably 0.38 g/cm³ or lower, the artificial leather can be made to have a flexible texture.

In addition, in the present invention, the apparent density of the artificial leather is calculated by measuring the thickness and mass per unit area of the artificial leather using the method specified in JIS L 1913:2010 “General Nonwoven Fabric Test Methods” 6.1.1 (Thickness Method A) and 6.2 (Mass per unit area), and using the following formula.

Apparent density of artificial leather (g/cm³) = Mass per unit area of artificial leather (g/cm²) / Thickness of artificial leather (cm).

The artificial leather of the present invention has a stiffness of 150 mm or less in the longitudinal direction of the sheet, as defined by Method A (45° cantilever method) described in Section 8.21 (Stiffness) of JIS L 1096:2010 “Test Method for Fabrics and Knits”. By setting the stiffness to this range, the artificial leather can be made to have excellent flexibility. By setting the stiffness to 150 mm or less, and more preferably 100 mm or less, the artificial leather can be made to have greater flexibility.

In the Martindale abrasion test specified by "8.19.5 E method (Martindale method)" of "8.19 Abrasion Strength and Friction Discoloration" of JIS L 1096:2005 "Test Methods for Fabrics and Knits," it is preferable that the abrasion loss is 30 mg or less when measured at 50,000 abrasion cycles. It is more preferable that the abrasion loss is 25 mg or less from the perspective of suppressing the deterioration of the appearance of the artificial leather.

In addition, the artificial leather of the present invention preferably has a wear loss of 10 mg or less when measured at 10,000 wear cycles in the Martindale abrasion test specified in "8.19.5 E method (Martindale method)" of "8.19 Abrasion Strength and Friction Discoloration" of JIS L 1096:2005 "Test Method for Fabrics and Knits" after performing xenon irradiation as specified in "7.2 Exposure Method a) First Exposure Method" of JIS L 0843:2006 "Test Method for Color Fastness to Xenon Arc Lamp". By having a wear loss of 10 mg or less after performing xenon irradiation, the artificial leather becomes a durable material capable of long-term use in areas exposed to sunlight, such as automobile seats.

[Method for manufacturing artificial leather]

The method for manufacturing artificial leather according to the present invention is a method for manufacturing artificial leather that includes the following processes (1) to (3) in this order.

(1) A process of forming a fibrous substrate by entangling and integrating a nonwoven fabric made of ultrafine fiber-expressing fibers and a fabric.

(2) A process of obtaining a shrink sheet having a width of 0.85L or more and 0.95L or less when the width is L, by impregnating the above fibrous substrate with an aqueous dispersion of a polyurethane having hydrophilic groups and then solidifying the polyurethane.

(3) A process for developing polyester microfibers from the microfiber-developing fibers of the above shrink sheet.

Details are explained below.

<Process of forming a fibrous substrate>

In this process, a nonwoven fabric made of ultrafine fiber-expressing fibers and a woven fabric are subjected to entanglement treatment to form a fibrous substrate.

As a fiber with a microfiber expression type, it is desirable to use a sea-island type composite fiber in which a two-component thermoplastic resin with different solvent solubility (two or three components in the case where the fiber is a core-sheath composite fiber) is used as the sea component and the sea component, and the sea component is dissolved and removed using a solvent or the like to make the sea component into a microfiber, because when the sea component is removed, a suitable void can be provided between the sea components, that is, between the microfibers inside the fiber bundle, from the perspective of the texture and surface quality of the artificial leather.

As for the sea island type composite fiber, a method using a polymer interarray that uses a sea island type composite fitting to mutually arrange and spin two components (three components if the sea fiber is a core sheath composite fiber) of a sea component and a sea component is preferred from the perspective that ultrafine fibers with a uniform single fiber diameter are obtained.

As the sea component of the sea-island type composite fiber, polyethylene, polypropylene, polystyrene, copolymerized polyester obtained by copolymerizing sodium sulfoisophthalic acid or polyethylene glycol, and polylactic acid, etc., can be used, but polystyrene or copolymerized polyester is preferably used from the perspective of yarnability and effluxability.

In the sea-island type composite fiber preferably used in the present invention, the mass ratio of the sea component to the island component is preferably in the range of sea component:island component = 10:90 to 80:20. If the mass ratio of the sea component is 10 mass% or more, the island component becomes sufficiently ultrafine. In addition, if the mass ratio of the sea component is 80 mass% or less, productivity is improved because the ratio of the leached component is low. More preferably, the mass ratio of the sea component to the island component is in the range of sea component:island component = 20:80 to 70:30.

In addition, as described above, both short-fiber and long-fiber nonwoven fabrics can be used as the nonwoven fabric constituting the fibrous substrate; however, a short-fiber nonwoven fabric is preferred because the fibers oriented in the thickness direction of the artificial leather are more numerous than those in a long-fiber nonwoven fabric, and a high density can be obtained on the surface of the artificial leather when napped.

When a short-fiber nonwoven fabric is used as the fibrous substrate, the obtained ultrafine fiber-forming fiber is preferably crimped and cut to a predetermined length to obtain an unprocessed surface. Known methods may be used for crimping or cutting.

Next, the obtained unprocessed surface is formed into a fiber web using a cross wrapper or the like. Then, a nonwoven fabric is obtained by entangling the obtained fiber web. As a method to obtain a nonwoven fabric by entangling the fiber web, needle punching or water jet punching can be used, but it is preferable to perform needle punching, which has high entangling efficiency.

In addition, the obtained nonwoven fabric and fabric are laminated and entangled together. For the entanglement of the nonwoven fabric and fabric, the fabric can be laminated on one or both sides of the nonwoven fabric, or the fabric can be sandwiched between multiple nonwoven webs, and then the fibers of the nonwoven fabric and fabric can be entangled by needle punching or water jet punching, but from the perspective of manufacturing efficiency, it is preferable to perform needle punching after laminating the fabric on both sides of the nonwoven fabric.

It is preferable that the apparent density of the fibrous substrate, which consists of a nonwoven fabric made of composite fibers (ultrafine fiber-expressing fibers) after entanglement treatment and a fabric, be 0.20 g/cm³ or higher and 0.30 g/cm³ or lower. By making the apparent density 0.20 g/cm³ or higher, more preferably 0.23 g/cm³ or higher, sufficient shape stability and dimensional stability are obtained for the fibrous substrate. On the other hand, by making the apparent density 0.30 g/cm³ or lower, more preferably 0.28 g/cm³ or lower, sufficient space can be maintained for imparting a polyurethane having hydrophilic groups.

Although it is possible to perform heat shrinkage treatment using hot water or steam on the above-mentioned fibrous substrate to improve the density of the fibers, since the present invention performs shrinkage treatment of the sheet after impregnating it with an aqueous dispersion containing a polyurethane precursor, it is preferable not to perform shrinkage treatment before impregnating it with the aqueous dispersion containing the polyurethane precursor.

Process of forming an impregnated sheet and shrinking it in the width direction

In this process, an aqueous dispersion containing a polyurethane precursor is impregnated into the above-mentioned fibrous substrate, and then a heat drying treatment is performed to form an impregnated sheet comprising a fibrous substrate and a polyurethane having hydrophilic groups as components, and then a shrinkage sheet is obtained in which the width is 0.85L or more and 0.95L or less when the width of the fibrous substrate before impregnation is L.

In the method for manufacturing artificial leather according to the present invention, coagulation after the application of an aqueous dispersion may be performed using a coagulation method commonly used in the field, such as a dry heat coagulation method or an in-liquid coagulation method. When using a dry heat coagulation method, it is preferable to apply an aqueous dispersion to a fibrous substrate, heat treat it at a temperature of 120°C or higher and 180°C or lower, and then perform dry heat coagulation to impart a polyurethane having hydrophilic groups to the fibrous substrate. Additionally, for in-liquid coagulation, an acid coagulation method in which coagulation treatment is performed with a coagulation solvent having a pH of 1 or higher and 3 or lower, or a hot water coagulation method in which coagulation treatment is performed with hot water having a temperature of 80°C or higher and 100°C or lower may be used.

It is preferable that the concentration of the polyurethane precursor in the aqueous dispersion (content of the polyurethane precursor in 100 mass% of the aqueous dispersion) be 3 mass% or more and 30 mass% or less. By setting it to 3 mass% or more, more preferably 5 mass% or more, the polyurethane precursor can be uniformly applied to the fibrous substrate even when the amount of polyurethane precursor applied is small. On the other hand, by setting it to 30 mass% or less, more preferably 15 mass% or less, the storage stability of the aqueous dispersion can be increased.

When using a dry heat coagulation method as the coagulation method, it is desirable to adjust the coagulation temperature to be 55°C or higher and 80°C or lower. By setting the coagulation temperature to 55°C or higher, more preferably 60°C or higher, gelation during the mixing of the aqueous dispersion or during storage can be suppressed. On the other hand, by setting the temperature to 80°C or lower, more preferably 70°C or lower, the coagulation of the polyurethane precursor proceeds before moisture evaporates from the fibrous substrate, thereby forming a structure similar to that obtained by wet coagulating solvent-based polyurethane—that is, a structure in which the polyurethane does not strongly restrain the fibers constituting the nonwoven fabric or woven fabric—it becomes possible to achieve good flexibility and resilience.

In the method for manufacturing artificial leather according to the present invention, when using a dry heat coagulation method, an inorganic salt may be contained in the aqueous dispersion. By containing an inorganic salt, heat-sensitive coagulation properties can be imparted to the aqueous dispersion. In the present invention, heat-sensitive coagulation properties refer to the property in which, when an aqueous dispersion is heated, its fluidity decreases and it coagulates upon reaching a certain temperature (coagulation temperature).

In the present invention, when using an inorganic salt as a thermal coagulant, it is preferable to use a monovalent cation-containing inorganic salt. The monovalent cation-containing inorganic salt is preferably sodium chloride and/or sodium sulfate. A monovalent cation-containing inorganic salt with a small ionic valence has little effect on the stability of the aqueous dispersion, and by adjusting the amount added, the thermal coagulation temperature can be strictly controlled while ensuring the stability of the aqueous dispersion.

In addition, in the present invention, the content of the monovalent cation-containing inorganic salt in the aqueous dispersion is preferably 10 mass% or more and 50 mass% or less relative to the polyurethane precursor. By setting the content to 10 mass% or more, more preferably 20 mass% or more, and even more preferably 30 mass% or more, the ions present in large quantities in the aqueous dispersion act uniformly on the polyurethane precursor particles, thereby enabling rapid completion of solidification at a specific thermal solidification temperature. Accordingly, a more significant effect can be obtained when proceeding with the solidification of the polyurethane precursor in a state containing a large amount of moisture in the fibrous substrate as described above. As a result, it is possible to form a structure very similar to that obtained by wet solidification of solvent-based polyurethane and to achieve good flexibility and resilience. In addition, by setting the addition amount as above, the inorganic salt acts as an inhibitor in the fusion of the particles of the polyurethane precursor, thereby suppressing the curing of the polyurethane precursor through the formation of a continuous film. On the other hand, by setting the content to 50 mass% or less, a suitable continuous film structure of the polyurethane precursor can be preserved, thereby suppressing the deterioration of physical properties. In addition, the stability of the aqueous dispersion can also be maintained.

In the method for manufacturing artificial leather according to the present invention, it is also preferable to include a crosslinking agent in the aqueous dispersion. By introducing a three-dimensional mesh structure into the polyurethane precursor through the crosslinking agent, physical properties such as wear resistance can be improved.

It is preferable that the concentration of the crosslinking agent in the above aqueous dispersion be 1 mass% or more and 10 mass% or less relative to the mass of the polyurethane precursor. By setting the concentration of the crosslinking agent in the aqueous dispersion to 1 mass% or more, more preferably 2 mass% or more, a three-dimensional mesh structure can be introduced more into the polyurethane precursor by the crosslinking agent, thereby enabling the production of artificial leather with excellent wear resistance. On the other hand, by setting the concentration to 10 mass% or less, more preferably 7 mass% or less, when the polyurethane precursor is formed, the excess crosslinking agent is prevented from inhibiting the solidification of the polyurethane precursor, and it becomes easier to suppress the deterioration of physical properties such as wear resistance.

In addition, the crosslinking agent preferably used in the method for manufacturing artificial leather according to the present invention is preferably a carbodiimide-based crosslinking agent and/or a block isocyanate crosslinking agent. By doing so, a three-dimensional crosslinking structure can be imparted to the molecules of the polymer elastomer in the artificial leather through N-acylurea bonds and/or isourea bonds, which have excellent physical properties such as light resistance, heat resistance, and wear resistance, as well as flexibility, thereby dramatically improving physical properties such as durability and wear resistance while maintaining the flexibility of the artificial leather.

Then, after impregnating and coagulating the above aqueous dispersion, a shrinkage sheet is obtained in which the width is 0.85L or more and 0.95L or less when the width of the fibrous substrate before impregnation is L. As a method for shrinking the sheet in the width direction, dry heat treatment at a temperature of 100°C or more and 180°C or hot water treatment at a temperature of 80°C or more and 100°C or less may be used. Examples of dry heat treatment include a treatment in which hot air is applied to one or both sides of the sheet using a floater dryer, a drum dryer, or a pin tender type dryer, and examples of hot water treatment include a treatment in which the sheet is immersed in hot water at a temperature of 80°C or more and 100°C or less, woven with a mangle, and then dried with a dryer.

In addition, from the perspective of manufacturing efficiency, it is desirable that the solidification method and shrinkage method of the aqueous dispersion be the same.

The density of the artificial leather surface can be increased by shrinking the sheet in the width direction. In particular, by shrinking the sheet in the width direction after impregnating and solidifying a water dispersion of polyurethane, the polyurethane is prevented from adhering firmly to the fabric, thereby making the texture of the artificial leather more flexible.

The degree of shrinkage in the width direction of the sheet can be determined by the temperature or time of the heat treatment, and the above effect can be sufficiently achieved by making it 5% or more, more preferably 10% or more, relative to the width of the fibrous substrate before impregnation.

Meanwhile, by keeping the width of the fibrous substrate before impregnation at 15% or less, quality defects such as wrinkle insertion into the sheet can be prevented.

When using dry heat treatment as a shrinkage treatment, the shrinkage of the sheet can be increased by setting the temperature of the dry heat treatment to 100°C or higher, preferably 120°C or higher, and more preferably 130°C or higher. Meanwhile, by setting the temperature of the dry heat treatment to 180°C or lower, preferably 160°C or lower, the decrease in the durability of the artificial leather due to the decomposition of polyurethane can be suppressed.

When using dry heat treatment as a shrinkage treatment, it is preferable that the dry heat treatment time be 5 minutes or more and 30 minutes or less. By heating for 5 minutes or more, more preferably 10 minutes or more, the shrinkage of the sheet can be increased. By setting the dry heat treatment time to 30 minutes or less, preferably 25 minutes or less, the decrease in the durability of the artificial leather due to the decomposition of polyurethane can be suppressed.

Process for developing polyester ultrafine fibers

In this process, polyester ultrafine fibers are developed from the ultrafine fiber-developing fibers of the above-mentioned shrinkage sheet, thereby forming a fibrous substrate composed of polyester ultrafine fibers and a fabric, and a sheet comprising a polyurethane having hydrophilic groups as a component.

When using a sea-island type composite fiber as a fiber capable of developing ultrafine fibers, the fiber ultrafine treatment (de-sealing treatment) can be performed by methods such as immersing the sea-island type composite fiber in a solvent and then performing a heat treatment. The solvent for dissolving the de-sealing component can be appropriately selected depending on the type of de-sealing component; if the de-sealing component is a copolymer polyester, an alkaline aqueous solution such as sodium hydroxide can be used, but it is preferable to perform an alkaline treatment using an alkaline aqueous solution, which is expected to have the effect of relaxing the adhesion between the fabric and the polyurethane.

When using an alkaline aqueous solution as a solvent for dewatering treatment, it is preferable that the molar concentration of the alkaline aqueous solution be 3 mol/L or less to prevent excessive deterioration of the polyurethane having hydrophilic groups.

Finishing Process

In the method for manufacturing artificial leather according to the present invention, it is preferable to perform various finishing processes, just as with general artificial leather.

First, the method for manufacturing artificial leather according to the present invention preferably includes a dyeing process for dyeing the artificial leather. Various methods commonly used in the field may be employed for this dyeing treatment. For example, immersion dyeing treatments such as liquid dyeing using a jig dyeing machine or a liquid dyeing machine, thermosol dyeing using a continuous dyeing machine, or printing treatments on the fiber surface such as roller printing, screen printing, inkjet printing, sublimation printing, and vacuum sublimation printing may be used. Among these, it is preferable to use a liquid dyeing machine because it can soften the microfiber artificial leather or artificial leather by applying a rubbing effect simultaneously with dyeing the microfiber artificial leather or artificial leather. Additionally, if necessary, various resin finishing treatments may be performed after dyeing.

In addition, a finishing agent treatment using, for example, a softener such as silicone, an antistatic agent, a water repellent, a flame retardant, a light-resistant agent, and an antibacterial agent can be performed during the dyeing process or after dyeing.

In the present invention, regardless of whether it is before or after the dyeing process, it is also a desirable form to re-materialize in the thickness direction from the perspective of manufacturing efficiency.

In the method for manufacturing artificial leather according to the present invention, it is preferable to include a napping process regardless of whether it is before or after the dyeing process. The method for forming the nap is not particularly limited, and various methods commonly practiced in the field, such as buffing with sandpaper, etc., may be used.

In the case of performing napping treatment, a lubricant such as a silicone emulsion may be applied to the surface of the artificial leather before napping treatment. In addition, by applying an antistatic agent before napping treatment, it becomes difficult for abrasive particles generated from the artificial leather by grinding to accumulate on the sandpaper. In this way, artificial leather is formed.

In addition, in the method for manufacturing artificial leather according to the present invention, post-processing treatments such as perforation, embossing, laser processing, pin sonic processing, and printing can be performed on the artificial leather as needed.

[Uses for vehicle interior materials, vehicle parts, seats, etc.]

The artificial leather obtained by the present invention can be suitably used as an interior material having a very elegant and beautiful appearance as a surface material for furniture, chairs, and wall materials, or as a surface material for seats, ceilings, and interiors in the interiors of vehicles such as automobiles, trams, and aircraft, as well as as uppers and trims of shoes such as shirts, jackets, casual shoes, sports shoes, men's shoes, and women's shoes, as well as as medical materials used in bags, belts, wallets, etc., and parts thereof, and as industrial materials such as Wiping Roast, abrasive cloths, and CD curtains.

For example, automotive interior materials including the above-described artificial leather are desirable because they can utilize characteristics such as high strength, excellent flexibility, and excellent wear resistance. Such automotive interior materials are preferably used in automotive parts such as, for example, steering wheels, horn switches, shift knobs, dashboards, instrument panels, glove boxes, floor carpets, floor mats, ceiling lining, sun visors, and assist grips, and it is more preferable that at least some of these automotive parts are made of the above-described artificial leather. Furthermore, the term "automobile" in the present invention is not limited to so-called general passenger cars, but also includes some industrial machinery, construction machinery, and agricultural machinery capable of transporting humans or animals, such as shovel cars, crane cars, tractors, and combines.

In addition, a seat containing the above-mentioned artificial leather is also desirable because it can utilize characteristics such as high strength, excellent flexibility, and excellent wear resistance. For such a seat, it is more preferable that at least a portion of the surface material, such as the headrest, seat surface, armrest, and footrest, for example, the part that comes into direct contact with the occupant, is made of the above-mentioned artificial leather. Of course, the seat of the present invention may be used not only for boarding in automobiles, aircraft, railway vehicles, ships, etc., but also for use in homes, offices, and shops. Furthermore, the term "seat" as used in the present invention includes chairs, benches, sofas, couches, stools, floor chairs, etc.

Examples

The artificial leather of the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

[Evaluation Method]

The evaluation method and measurement conditions used in the examples are described. In addition, regarding the measurement of each physical property, unless otherwise specified, the measurement was performed based on the above method.

(1) Average single fiber diameter (㎛):

The average single fiber diameter (μm) was measured and calculated using the above method with a Keyence Corporation “VHX-D500/D510” scanning electron microscope (SEM).

(2) Content ratio (mass%) of polyurethane having hydrophilic groups:

The content ratio (mass%) of polyurethane having hydrophilic groups was measured and calculated by the above method.

(3) Percentage of filaments with polyurethane attached among the outermost filaments of the multifilament (%):

The ratio (%) of filaments to which polyurethane is attached among the outermost filaments of the multifilament was measured and calculated by the above method.

(4) Strength of artificial leather:

Based on Method A (45° cantilever method) described in 8.21.1 of 8.21 "Strength" of JIS L 1096:2010 "Test Method for Fabrics and Knits," five test specimens measuring 2 cm × 30 cm were prepared in the longitudinal direction of the sheet, placed on a horizontal bar having a 45° angled bevel, and slid the test specimens. The scale was read when the center point of one end of the test specimen came into contact with the bevel, and the average value of the five specimens was calculated.

(5) Wear loss of artificial leather (mg):

In measuring and calculating the wear loss (mg) of artificial leather, the James H. Heal & Co. "Model 406" Martindale abrasion tester and the company's "ABRASTIVE CLOTH SM25" were used as the standard friction cloth. Then, a load of 12 kPa was applied to the artificial leather and measurements were taken for 50,000 wear cycles, and the wear loss was calculated using the following formula based on the mass of the artificial leather before and after wear.

Loss on wear (mg) = Mass before wear (mg) - Mass after wear (mg)

In addition, the wear loss (mg) was defined as the value rounded to the nearest whole number.

(6) Loss of wear on artificial leather after xenon irradiation (mg):

In measuring and calculating the loss on abrasion (mg) of artificial leather after xenon irradiation, after performing irradiation as specified in “7.2 Exposure Method a) First Exposure Method” of JIS L 0843:2006 “Test Method for Color Fastness to Xenon Arc Lamps”, a “Model 406” manufactured by James H. Heal & Co. was used as the Martindale abrasion tester and the company’s “ABRASTIVE CLOTH SM25” was used as the standard friction cloth. Then, a load of 12 kPa was applied to the artificial leather and measurements were taken for 10,000 abrasion cycles, and the loss on abrasion was calculated using the following formula based on the mass of the artificial leather before and after abrasion.

Loss on wear (mg) = Mass before wear (mg) - Mass after wear (mg)

In addition, the wear loss (mg) was defined as the value rounded to the nearest whole number.

[Polyurethane Precursor]

The polyurethane precursors used in the examples and comparative examples are as follows.

PU-A (polyether-based polyurethane precursor comprising a component derived from a polyether-based polyol): a polyurethane precursor comprising polytetramethylene glycol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as a compound containing an active hydrogen component having a hydrophilic group, and ethylene glycol as a chain extender.

PU-B (polycarbonate-based polyurethane precursor comprising a component derived from a polycarbonate-based polyol): a polyurethane precursor comprising polyhexamethylene carbonate diol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as a compound containing an active hydrogen component having a hydrophilic group, and ethylene glycol as a chain extender.

[textile]

The fabrics used in the examples and comparative examples are as follows.

Fabric A: A plain weave fabric with a weft density of 95 warp fibers/2.54 cm and 76 weft fibers/2.54 cm (weight per unit area 75 g/m²), using a twisted yarn of 2,500 T/m applied to a multifilament composed of 72 filaments of polyethylene terephthalate with an intrinsic viscosity of 0.65 and an average staple fiber diameter of 11 μm, used in both the warp and weft directions.

Fabric B: A plain weave fabric with a weft density of 95 warp fibers/2.54 cm and 76 weft fibers/2.54 cm (weight per unit area 75 g/m²), using a twisted yarn of 2,500 T/m applied to a multifilament composed of 40 filaments of polyethylene terephthalate with an intrinsic viscosity of 0.65 and an average staple fiber diameter of 15 μm, used in both the warp and weft directions.

Fabric C: A plain weave fabric with a weft density of 190 warp fibers/2.54 cm and 152 weft fibers/2.54 cm (weight per unit area 75 g/m²), using a twisted yarn of 2,500 T/m applied to a multifilament composed of 68 filaments of polyethylene terephthalate with an intrinsic viscosity of 0.65 and an average staple fiber diameter of 8 μm, used in both the warp and weft directions.

[Example 1]

<Process of forming a fibrous substrate>

Polyester copolymerized with 8 mol% sodium 5-sulfoisophthalate as the sea component and polyethylene terephthalate with an intrinsic viscosity of 0.73 as the sea component were used, and a sea-island type composite die with a sea number of 16 degrees/hole was used. Melt spinning was performed under conditions of a spinning temperature of 285°C, a sea/sea mass ratio of 80/20, an extrusion rate of 1.6 g/min·hole, and a spinning speed of 1,100 m/min. Subsequently, the fiber was stretched 3.7 times in an emulsion bath and cut to a length of 51 mm to obtain an unprocessed surface of a sea-island type composite fiber with a staple fiber fineness of 3.8 dtex. Next, using the unprocessed surface of the above-mentioned sea-island type composite fiber, a laminated web having an apparent density of 0.09 g/cm³ was formed through carding and cross-wrapping processes, fabric A was laminated, and needle-punched at a punch density of 3,500 pieces/cm² was obtained, thereby obtaining a fibrous substrate consisting of a nonwoven fabric and a fabric made of sea-island type composite fiber having a weight per unit area of 690 g/m², a thickness of 3.0 mm, a width of 170 cm, and an apparent density of 0.23 g/cm³.

Process of forming an impregnated sheet and shrinking it in the width direction

As a polyurethane precursor, an aqueous dispersion was prepared comprising 12 parts by mass of PU-A, a polyether-based polyurethane precursor, 1 part by mass of a carbodiimide-based crosslinking agent (V-02-L2, "Carbodilite" (registered trademark) manufactured by Nisshinbo Chemical Inc.), 5 parts by mass of sodium sulfate, and 82 parts by mass of water. After impregnating a fibrous substrate, the aqueous dispersion was woven into a mangle such that the pickup rate of the aqueous dispersion was 200% of the mass ratio of the fibrous substrate. After solidifying the polyurethane precursor by heating with hot air at 100°C for 10 minutes, the sheet was heated with hot air at 150°C for 10 minutes to shrink the sheet by 12% in the width direction relative to the width (L) of the fibrous substrate before impregnation, thereby obtaining an impregnated sheet having a width of 150 cm (0.88 L) and composed of a nonwoven fabric and fabric of a sea-island type composite fiber and a polyurethane having hydrophilic groups.

Process for developing polyester ultrafine fibers

After immersing the obtained impregnated sheet in a 5% aqueous sodium hydroxide solution, weave it with a mangle so that the pickup rate of the aqueous sodium hydroxide solution becomes 100%, and heat treat it in steam at 95°C for 10 minutes to alkaline decompose the sea island-type composite fiber, and then wash off the excess sodium hydroxide to obtain a sheet made of polyester ultrafine fibers, fabric, and polyurethane having hydrophilic groups.

Finishing Process

A sheet with a thickness of 0.9 mm was obtained by re-grinding the obtained sheet perpendicularly in the thickness direction and grinding the re-grinded surface with endless sandpaper with a grit of 180.

The obtained fiber sheet was dyed using a disperse dye in a liquid-flow dyeing machine at a temperature of 120°C. Subsequently, the material was dried in a dryer to obtain an artificial leather containing 23 mass% of polyurethane having hydrophilic groups and an average single fiber diameter of 4.4 μm of ultrafine fibers. Among the filaments on the outermost periphery of the multifilaments constituting the fabric of the obtained artificial leather, the proportion (%) of filaments to which polyurethane is attached was 30%, and the artificial leather had a flexible feel and excellent durability. The results are shown in Table 1.

[Example 2]

In the process of forming a fibrous substrate, the fabric was replaced with fabric B, except that the fabric was replaced with fabric B, and an artificial leather was obtained containing 23 mass% of a polyurethane having hydrophilic groups and an average single fiber diameter of the ultrafine fibers of 4.4 μm. In addition, the width of the impregnated sheet obtained by the process of forming an impregnated sheet and shrinking it in the width direction was 150 cm (0.88 L), which was shrunk by 12% in the width direction compared to the width (L) of the fibrous substrate before impregnation.

Among the outermost filaments of the multifilaments constituting the obtained artificial leather fabric, the proportion (%) of filaments to which polyurethane is attached is 45%, and although the flexibility is slightly inferior compared to Example 1, the artificial leather had a flexible feel and excellent durability. The results are shown in Table 1.

[Example 3]

In the process of forming a fibrous substrate, the fabric was replaced with fabric C, except that the fabric was replaced with fabric C, and an artificial leather was obtained containing 23 mass% of a polyurethane having hydrophilic groups and an average single fiber diameter of 4.4 μm of ultrafine fibers. In addition, the width of the impregnated sheet obtained by the process of forming an impregnated sheet and shrinking it in the width direction was 150 cm (0.88 L), which was shrunk by 12% in the width direction compared to the width (L) of the fibrous substrate before impregnation.

Among the outermost filaments of the multifilaments constituting the obtained artificial leather fabric, the proportion (%) of filaments to which polyurethane is attached is 65%, and although the flexibility is slightly inferior compared to Example 1, the artificial leather had a flexible feel and excellent durability. The results are shown in Table 1.

[Example 4]

In the process of <forming an impregnated sheet and shrinking it in the width direction>, the heating conditions after solidifying the polyurethane precursor were changed to 10 minutes in hot air at 120°C, in the same manner as in Example 1, and an artificial leather was obtained containing 23 mass% of a polyurethane having hydrophilic groups and an average single fiber diameter of the ultrafine fibers of 4.4 μm. In addition, the width of the impregnated sheet obtained by the process of <forming an impregnated sheet and shrinking it in the width direction> was 160 cm (0.94 L), which was shrunk by 6% in the width direction compared to the width (L) of the fibrous substrate before impregnation.

Among the outermost filaments of the multifilaments constituting the obtained artificial leather fabric, the proportion (%) of filaments to which polyurethane is attached is 39%, and although the flexibility is slightly inferior compared to Example 1, the artificial leather had a flexible feel and excellent durability. The results are shown in Table 1.

[Example 5]

In the process of <forming an impregnated sheet and shrinking it in the width direction>, the same procedure as in Example 1 was followed, except that the polyurethane precursor was changed to PU-B, a polycarbonate-based polyurethane precursor, and an artificial leather containing 23 mass% of a polyurethane having hydrophilic groups and an average single fiber diameter of 4.4 μm of ultrafine fibers was obtained. In addition, the width of the impregnated sheet obtained by the process of <forming an impregnated sheet and shrinking it in the width direction> was 150 cm (0.88 L), which was shrunk by 12% in the width direction compared to the width (L) of the fibrous substrate before impregnation.

Among the outermost filaments of the multifilaments constituting the obtained artificial leather fabric, the proportion (%) of filaments to which polyurethane is attached is 32%, and although the flexibility is slightly inferior compared to Example 1, the artificial leather had a flexible feel and extremely excellent durability. The results are shown in Table 1.

[Example 6]

In the process of <forming an impregnated sheet and shrinking it in the width direction>, except that the pickup rate of the water dispersion was set to 140% of the mass ratio of the fibrous substrate, the same procedure as in Example 1 was performed to obtain an artificial leather containing 18 mass% of a polyurethane having hydrophilic groups and an average single fiber diameter of the ultrafine fibers of 4.4 μm. In addition, the width of the impregnated sheet obtained by the process of <forming an impregnated sheet and shrinking it in the width direction> was 150 cm (0.88 L), which was shrunk by 12% in the width direction compared to the width (L) of the fibrous substrate before impregnation.

Among the outermost filaments of the multifilaments constituting the obtained artificial leather fabric, the proportion (%) of filaments to which polyurethane is attached is 22%, and the artificial leather had a flexible feel and excellent durability. The results are shown in Table 1.

[Example 7]

In the process of <forming an impregnated sheet and shrinking it in the width direction>, the process was carried out in the same manner as in Example 1, except that the solidification of the polyurethane precursor and the heating conditions after solidification were changed to steam at 98°C, and an artificial leather containing 23 mass% of a polyurethane having hydrophilic groups and an average single fiber diameter of the ultrafine fibers was 4.4 μm. In addition, the width of the impregnated sheet obtained by the process of <forming an impregnated sheet and shrinking it in the width direction> was 162 cm (0.95 L), which was shrunk by 5% in the width direction compared to the width (L) of the fibrous substrate before impregnation.

Among the outermost filaments of the multifilaments constituting the obtained artificial leather fabric, the proportion (%) of filaments to which polyurethane is attached is 47%, and although the flexibility is slightly inferior compared to Example 1, the artificial leather had a flexible feel and excellent durability. The results are shown in Table 1.

[Example 8]

In the process of developing polyester ultrafine fibers, the process was carried out in the same manner as in Example 1, except that the concentration of sodium hydroxide was changed to 3% and the pickup rate to 200%, thereby obtaining an artificial leather containing 23 mass% of a polyurethane having hydrophilic groups and an average single fiber diameter of the ultrafine fibers of 4.4 μm. In addition, the width of the impregnated sheet obtained by the process of forming an impregnated sheet and shrinking it in the width direction was 150 cm (0.88 L), which was shrunk by 12% in the width direction compared to the width (L) of the fibrous substrate before impregnation.

Among the outermost filaments of the multifilaments constituting the obtained artificial leather fabric, the proportion (%) of filaments to which polyurethane is attached is 40%, and although the flexibility is slightly inferior compared to Example 1, the artificial leather had a flexible feel and extremely excellent durability. The results are shown in Table 1.

[Comparative Example 1]

In the process of <forming an impregnated sheet and shrinking in the width direction>, the fibrous substrate was shrunk in the width direction to 150 cm in hot water at 97°C before impregnating with the aqueous dispersion, and the shrinkage in the width direction after the solidification of the polyurethane precursor was not performed; except for this, the process was carried out in the same manner as in Example 1, and an artificial leather containing 23 mass% of a polyurethane having hydrophilic groups and an average single fiber diameter of the ultrafine fibers was 4.4 μm. In addition, the width of the impregnated sheet obtained by the process of <forming an impregnated sheet and shrinking in the width direction> was not shrunk in the width direction relative to the width (L) of the fibrous substrate before impregnation, and remained at 150 cm (1.00 L).

Among the outermost filaments of the multifilaments constituting the filaments of the obtained artificial leather, the proportion (%) of fibers to which polyurethane is attached is 95%, and the obtained artificial leather has excellent durability but a hard texture. The results are shown in Table 1.

[Comparative Example 2]

In the process of <forming an impregnated sheet and shrinking it in the width direction>, except that the pickup rate of the water dispersion was set to 100% of the mass ratio of the fibrous substrate, the same procedure as in Example 1 was performed to obtain an artificial leather containing 13 mass% of a polyurethane having hydrophilic groups and an average single fiber diameter of the ultrafine fibers of 4.4 μm. In addition, the width of the impregnated sheet obtained by the process of <forming an impregnated sheet and shrinking it in the width direction> was 150 cm (0.88 L), which was shrunk by 12% in the width direction compared to the width (L) of the fibrous substrate before impregnation.

Among the outermost filaments of the multifilaments constituting the fabric of the obtained artificial leather, the proportion (%) of filaments to which polyurethane is attached is 8%, and the obtained artificial leather has excellent texture but is significantly inferior in durability. The results are shown in Table 1.

[Comparative Example 3]

In the process of <forming an impregnated sheet and shrinking it in the width direction>, except that the pickup rate of the water dispersion was set to 250% of the mass ratio of the fibrous substrate, the same procedure as in Example 1 was performed to obtain an artificial leather containing 29 mass% of a polyurethane having hydrophilic groups and an average single fiber diameter of 4.4 μm of ultrafine fibers. In addition, the width of the impregnated sheet obtained by the process of <forming an impregnated sheet and shrinking it in the width direction> was 150 cm (0.88 L), which was shrunk by 12% in the width direction compared to the width (L) of the fibrous substrate before impregnation.

Among the outermost filaments of the multifilaments constituting the fabric of the obtained artificial leather, the proportion (%) of filaments to which polyurethane is attached is 82%, and the obtained artificial leather has excellent durability but a hard texture. The results are shown in Table 1.

[Comparative Example 4]

In the process of <forming an impregnated sheet and shrinking in the width direction>, before impregnating with an aqueous dispersion, the fibrous substrate was shrunk in the width direction to 150 cm in hot water at 97°C, and 10 mass% of polyvinyl alcohol with a degree of saponification of 98% was applied relative to the mass of the fibrous substrate, and an artificial leather was obtained containing 23 mass% of polyurethane having hydrophilic groups and an average single fiber diameter of ultrafine fibers of 4.4 μm. In addition, the width of the impregnated sheet obtained by the process of <forming an impregnated sheet and shrinking in the width direction> was not shrunk in the width direction relative to the width (L) of the fibrous substrate before impregnation, and remained at 150 cm (1.00 L).

Among the outermost filaments of the multifilaments constituting the filaments of the obtained artificial leather, the proportion (%) of fibers to which polyurethane is attached is 95%, and the obtained artificial leather has excellent durability but a hard texture. The results are shown in Table 1.

<Process of forming a fibrous substrate>

In the same manner as in Example 1, a fibrous substrate consisting of a nonwoven fabric and a fabric made of a composite fiber was obtained.

Process of forming an impregnated sheet and shrinking it in the width direction

Before impregnating with an aqueous dispersion, the fibrous substrate was shrunk in the width direction to 150 cm in hot water at 97°C, and at the same time, 10 mass% of polyvinyl alcohol with a degree of saponification of 98% was applied relative to the mass of the fibrous substrate, and a fibrous substrate with polyvinyl alcohol attached was obtained by drying with hot air at 100°C. Next, as a polyurethane precursor, an aqueous dispersion was prepared comprising 12 parts by mass of PU-A, a polyether-based polyurethane precursor, 1 part by mass of a carbodiimide-based crosslinking agent (Nisshinbo Chemical Inc. product "Carbodilite" (registered trademark) V-02-L2), 5 parts by mass of sodium sulfate, and 82 parts by mass of water. After impregnating a fibrous substrate, the aqueous dispersion was woven with a mangle so that the pickup rate of the aqueous dispersion was 200% of the mass ratio of the fibrous substrate. The mixture was then heated with hot air at 100°C for 10 minutes to solidify the polyurethane precursor, and then heated with hot air at 150°C for 10 minutes to obtain a nonwoven fabric and woven fabric of a sea-island type composite fiber, an impregnated sheet composed of a polyurethane having hydrophilic groups and polyvinyl alcohol.

Process for developing polyester ultrafine fibers

The obtained impregnated sheet was subjected to alkali treatment in the same manner as in Example 1 to develop polyester ultrafine fibers, and polyvinyl alcohol was removed in hot water at 100°C to obtain a sheet composed of polyester ultrafine fibers, fabric, and polyurethane having hydrophilic groups.

Finishing Process

The obtained sheet was subjected to finishing treatment in the same manner as in Example 1, and an artificial leather was obtained containing 23 mass% of polyurethane having hydrophilic groups and an average single fiber diameter of the ultrafine fibers of 4.4 μm. Among the filaments on the outermost periphery of the multifilaments constituting the fabric of the obtained artificial leather, the ratio (%) of filaments to which polyurethane is attached is 3%. Although the artificial leather has a flexible feel and excellent durability, the process load was higher compared to Example 1 because polyvinyl alcohol was used. The results are shown in Table 1.

Industrial applicability

The artificial leather obtained by the present invention can be suitably used as an interior material having a very elegant and beautiful appearance as a surface material for furniture, chairs, and wall materials, or as a surface material for seats, ceilings, and interiors in the interiors of vehicles such as automobiles, trams, and aircraft, or as an upper, trim, etc. of shoes such as shirts, jackets, casual shoes, sports shoes, men's shoes, and women's shoes, or as a medical material used in bags, belts, wallets, etc., and parts thereof, or as an industrial material such as a bandage, abrasive cloth, and CD curtain.

1: Multifilaments that make up the fabric
2: Polyurethane
3: Filament with attached polyurethane
4: Filament without attached polyurethane

Claims (9)

Artificial leather comprising a fibrous substrate formed by the intertwining and integration of nonwoven fabric and fabric, and polyurethane having hydrophilic groups,
The above nonwoven fabric is composed of polyester ultrafine fibers having an average staple fiber diameter of 0.1㎛ or more and 10.0㎛ or less, and
The above fabric is composed of multifilaments having a number of filaments ranging from 30 to 300, and additionally, the average staple fiber diameter of the filaments constituting the multifilaments is 1㎛ or more and 30㎛ or less, and
The content ratio of the polyurethane in the above artificial leather is 15 mass% or more and 25 mass% or less, and
In addition, artificial leather in which the ratio of the filaments to which the polyurethane is attached among the outermost filaments of the above multifilament is 10% or more and 80% or less. In Article 1,
Artificial leather in which the above polyurethane is a polyether-based polyurethane and/or a polycarbonate-based polyurethane. A method for manufacturing artificial leather as described in claim 1,
A method for manufacturing artificial leather comprising the following processes (1) to (3) in this order.
(1) A process of forming a fibrous substrate by entangling and integrating a nonwoven fabric made of ultrafine fiber-expressing fibers and a fabric.
(2) A process of obtaining a shrink sheet having a width of 0.85L or more and 0.95L or less, wherein the width of the fibrous substrate before impregnation is L, with respect to the sheet obtained by impregnating the fibrous substrate with an aqueous dispersion of a polyurethane having hydrophilic groups and then solidifying the polyurethane.
(3) A process for developing polyester microfibers from the microfiber-developing fibers of the above shrink sheet. In Paragraph 3,
A method for manufacturing artificial leather in which the means of entanglement integration in the above process (1) is needle punch processing. In Article 3 or Article 4,
A method for manufacturing artificial leather, wherein the means for obtaining the shrink sheet in the above process (2) is a dry heat treatment at an atmosphere temperature of 100°C or higher and 180°C or lower. In Article 3 or Article 4,
A method for manufacturing artificial leather in which the means for producing polyester ultrafine fibers in the above process (3) is alkali treatment. Automotive interior material comprising the artificial leather described in claim 1 or 2. An automobile part comprising the artificial leather described in claim 1 or 2. A seat comprising the artificial leather described in Article 1 or Article 2.