Patent Description:
A polyurethane resin is widely used in the production of a synthetic leather (including an artificial leather) due to mechanical strength and good texture of the resin. In the application, a solvent-based urethane resin containing N,N-dimethylformamide (DMF) has been the mainstream so far. However, due to DMF regulation in Europe, strengthening of VOC emission regulation in China and Taiwan, and DMF regulation by major apparel makers, de-DMF of a urethane resin for each layer constituting a synthetic leather has been required.

To be compatible with such an environment, an aqueous urethane resin composition in which a urethane resin is dispersed in water has been widely studied (for example, see PTL <NUM>). As in the invention described in PTL <NUM>, for a skin layer of a synthetic leather, the replacement of a solvent-based urethane resin with an aqueous urethane resin is gradually increasing in the market, but use of an aqueous urethane resin for an intermediate layer has not yet progressed. This is mainly because the peeling strength of the aqueous urethane resin is insufficient compared with the solvent-based urethane resin. Therefore, it has been still difficult to produce an environmentally compatible synthetic leather for both the intermediate layer and the skin layer.

PTL <NUM> discloses a synthetic leather which is said to be excellent in wear resistance and hydrolysis resistance. The leather includes a skin layer and/or a surface-treated layer obtained from an aqueous urethane resin that is a reaction product of a polyol, a polyisocyanate and a reactive silicone having a number average molecular weight of <NUM>,<NUM> or more.

An object to be achieved by the present invention is to provide a synthetic leather having excellent abrasion resistance, peeling strength, hydrolysis resistance, and light resistance.

The present invention provides a synthetic leather at least including a base fabric (i), an intermediate layer (ii), and a skin layer (iii), in which the intermediate layer (ii) is formed of an aqueous urethane resin composition (C) containing a urethane resin (A) and an aqueous medium (B), the urethane resin (A) is a reaction product of a polyol (a1) containing a polyol (a1-<NUM>) having an anionic group, an aromatic polyisocyanate (a2) and a chain extender (a3), and has an anionic group in a concentration of <NUM> mmol/g or less, the skin layer (iii) is formed of an aqueous urethane resin composition (Z) containing a urethane resin (X) and an aqueous medium (Y), and the urethane resin (X) is a reaction product obtained by using a polyol (b1), a reactive silicone (b2) having a functional group which reacts with an isocyanate group, and a polyisocyanate (b3) as essential raw materials.

The synthetic leather of the present invention has excellent environmental compatibility because both the intermediate layer and the skin layer are formed of an aqueous urethane resin composition, and has excellent abrasion resistance, peeling strength, hydrolysis resistance, and light resistance.

Therefore, the synthetic leather of the present invention can be used for applications requiring high durability, such as an automobile interior material, furniture, and sports shoes, for which the replacement of a solvent-based urethane resin with an aqueous urethane resin has been considered difficult.

The synthetic leather of the present invention is a synthetic leather at least including a base fabric (i), an intermediate layer (ii), and a skin layer (iii), in which the intermediate layer (ii) is formed of an aqueous urethane resin composition (C) containing a urethane resin (A) and an aqueous medium (B), the urethane resin (A) is a reaction product of a polyol (a1) containing a polyol (a1-<NUM>) having an anionic group, an aromatic polyisocyanate (a2) and a chain extender (a3), and has an anionic group in a concentration of <NUM> mmol/g or less, the skin layer (iii) is formed of an aqueous urethane resin composition (Z) containing a urethane resin (X) and an aqueous medium (Y), and the urethane resin (X) is a reaction product obtained by using a polyol (b1), reactive silicone (b2) having a functional group which reacts with an isocyanate group, and a polyisocyanate (b3) as essential raw materials.

As the base fabric (i), for example, a non-woven fabric, a woven fabric, a knit, or the like made of polyester fiber, polyethylene fiber, nylon fiber, acrylic fiber, polyurethane fiber, acetate fiber, rayon fiber, polylactic acid fiber, cotton, hemp, silk, wool, glass fiber, carbon fiber, and blended fiber thereof can be used. Moreover, as the base fabric (i), a known impregnated base fabric obtained by impregnating these fabrics with a polyurethane resin can also be used.

It is essential that the intermediate layer (ii) is formed of the aqueous urethane resin composition (C) containing the urethane resin (A) and the aqueous medium (B), and the urethane resin (A) is a reaction product of the polyol (a1) containing the polyol (a1-<NUM>) having an anionic group, the aromatic polyisocyanate (a2) and a chain extender (a3), and has an anionic group in a concentration of <NUM> mmol/g or less.

The polyol (a1-<NUM>) having an anionic group is a raw material for obtaining an anionic urethane resin, and for example, polyol having a carboxyl group, such as <NUM>,<NUM>'-dimethylolpropionic acid, <NUM>,<NUM>'-dimethylolbutanoic acid, <NUM>,<NUM>'-dimethylolbutyric acid, and <NUM>,<NUM>'-valeric acid; polyol having a sulfonyl group, such as <NUM>,<NUM>-dimethylolbutanesulfonic acid and <NUM>,<NUM>-dimethylol-<NUM>-toluenesulfonic acid; or the like can be used. These compounds may be used alone or in a combination of two or more kinds thereof.

From the viewpoint that the concentration of the anionic group in the polyurethane resin (A) is easily prepared within the range described in the present invention, and far superior hydrolysis resistance is obtained, the content of the polyol (a1-<NUM>) in the polyol (a1) is preferably <NUM>% to <NUM>% by mass, more preferably <NUM>% to <NUM>% by mass, still more preferably <NUM>% to <NUM>% by mass, and particularly preferably <NUM>% to <NUM>% by mass.

In the polyol (a1), as polyol which can be used other than the polyol (a1-<NUM>), for example, polyether polyol, polyester polyol, polycarbonate polyol, dimer diol, acrylic polyol, polybutadiene polyol, or the like can be used. The polyol may be used alone or in a combination of two or more kinds thereof. Among them, from the viewpoint that hydrolysis resistance can be further improved, polyether polyol and/or polycarbonate polyol is preferably used.

From the viewpoint that far superior peeling strength, mechanical strength of the film, and hydrolysis resistance are obtained, the number-average molecular weight of the polyol (a1) is preferably <NUM> to <NUM>,<NUM> and more preferably <NUM> to <NUM>,<NUM>. Moreover, the number-average molecular weight of the polyol (a1) indicates a value obtained by a gel permeation column chromatography (GPC) method.

The polyol is used in a combination with a chain extender (a3).

The chain extender is an aliphatic polyol compound such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, <NUM>,<NUM>-propanediol, <NUM>,<NUM>-butanediol, <NUM>,<NUM>-butanediol, hexamethylene glycol, saccharose, methylene glycol, glycerin, and sorbitol; an aromatic polyol compound such as bisphenol A, <NUM>,<NUM>'-dihydroxydiphenyl, <NUM>,<NUM>'-dihydroxydiphenyl ether, <NUM>,<NUM>' -dihydroxydiphenylsulfone, hydrogenated bisphenol A, and hydroquinone; water; or the like can be used. These chain extenders may be used alone or in a combination of two or more kinds thereof. Among them, from the viewpoint that discoloration is easily prevented and far superior light resistance is obtained, an aliphatic polyol compound is preferably used.

The amount of the chain extender used is preferably <NUM>% to <NUM>% by mass and more preferably <NUM>% to <NUM>% by mass in the total mass of the core raw materials constituting the urethane resin (A), from the viewpoint that durability of the film can be further improved.

The aromatic polyisocyanate (a2) has a strong intermolecular force and is an essential component for obtaining excellent peeling strength due to a packing effect. As the aromatic polyisocyanate (a2), from the viewpoint that crystallinity is adequately weak and far superior peeling strength is obtained, toluene diisocyanate is used.

The amount of the toluene diisocyanate used is preferably <NUM>% by mass or more and more preferably <NUM>% by mass or more in the aromatic polyisocyanate (a2), from the viewpoint that far superior peeling strength is obtained.

The aromatic polyisocyanate (a2) may be used in a combination with aliphatic or alicyclic polyisocyanate as long as the effects of the present invention are not impaired.

Examples of a method for producing the urethane resin (A) include a method in which the polyol (a1), the aromatic polyisocyanate (a2), and the chain extender (a3) are charged at once and reacted with one another. The reaction may be carried out, for example, at a temperature of <NUM> to <NUM> for <NUM> to <NUM> hours.

A molar ratio [(isocyanate group)/(total of hydroxyl group and amino group)] of the isocyanate group of the aromatic polyisocyanate (a2) to the hydroxyl group of the polyol (a1) and, when the chain extender is used, the total of the hydroxyl groups of the chain extender is preferably <NUM> to <NUM> and more preferably <NUM> to <NUM>.

When the urethane resin (A) is produced, the isocyanate groups remaining in the urethane resin (A) are preferably deactivated. When the isocyanate groups are deactivated, alcohol having a hydroxyl group, such as methanol, is preferably used. When the alcohol is used, the amount of the alcohol used is preferably <NUM> to <NUM> parts by mass with respect to <NUM> parts by mass of the urethane resin (A).

Furthermore, when the urethane resin (A) is produced, an organic solvent may be used. As the organic solvent, for example, a ketone compound such as acetone and methyl ethyl ketone; an ether compound such as tetrahydrofuran and dioxane; an acetate ester compound such as ethyl acetate and butyl acetate; a nitrile compound such as acetonitrile; an amide compound such as a dimethylformamide and N-methylpyrrolidone; or the like can be used. These organic solvents may be used alone or in a combination of two or more kinds thereof. Moreover, the organic solvent is preferably removed by a distillation method or the like when the aqueous urethane resin composition (C) is obtained.

In a case of the urethane resin (A) obtained by the method, in order to obtain excellent hydrolysis resistance, it is essential that the concentration of the anionic group is <NUM> mmol/g or less. Within this range, while water dispersibility or peeling strength of the urethane resin (A) is maintained, degradation in hydrolysis resistance due to a hydrophilic group can be prevented. From the viewpoint that far superior hydrolysis resistance is obtained, the concentration of the anionic group in the urethane resin (A) is preferably <NUM> mmol/g or less, more preferably <NUM> to <NUM> mmol/g, and still more preferably <NUM> to <NUM> mmol/g. Moreover, the concentration of the anionic group in the urethane resin (A) indicates a value obtained by dividing the number of moles of the anionic group derived from the polyol (a1-<NUM>) having the anionic group by the total mass of the respective raw materials constituting the urethane resin (A).

Furthermore, from the viewpoint that far superior peeling strength is obtained, the concentration of the aromatic ring in the urethane resin (A) is preferably <NUM> to <NUM> mol/kg and more preferably <NUM> to <NUM> mol/kg. In the calculation, the molecular weight of benzene or naphthalene having no substituent is used as the molecular weight of the aromatic ring.

From the viewpoint that far superior peeling strength is obtained, the weight-average molecular weight of the urethane resin (A) is preferably <NUM>,<NUM> to <NUM>,<NUM>, more preferably <NUM>,<NUM> to <NUM>,<NUM>, and still more preferably <NUM>,<NUM> to <NUM>,<NUM>. Moreover, the weight-average molecular weight of the urethane resin (A) indicates a value obtained by measuring in the same manner as the number-average molecular weight of the polyol (a1).

As the aqueous medium (B), for example, water, an organic solvent miscible with water, a mixture thereof, or the like can be used. As the organic solvent miscible with water, for example, an alcohol solvent such as methanol, ethanol, and n- and isopropanol; a ketone solvent such as acetone and methyl ethyl ketone; a polyalkylene glycol solvent such as ethylene glycol, diethylene glycol, and propylene glycol; an alkyl ether solvent such as a polyalkylene glycol; a lactam solvent such as N-methyl-<NUM>-pyrrolidone; or the like can be used. These aqueous media may be used alone or in a combination of two or more kinds thereof. Among them, from the viewpoint of safety and reduction in an environmental load, only water or a mixture of water and an organic solvent miscible with water is preferably used and only water is more preferably used. From the viewpoint of workability, coatability, and storage stability, the content of the aqueous medium (B) in the aqueous urethane resin composition (C) is preferably <NUM>% to <NUM>% by mass and more preferably <NUM>% to <NUM>% by mass.

The aqueous urethane resin composition (C) used in the present invention contains the urethane resin (A) and the aqueous medium (B) as essential components.

However, as other additives, for example, a urethanization catalyst, a neutralizer, a crosslinking agent, a silane coupling agent, a thickener, a filler, a thixotropic agent, a tackifier, a wax, a heat stabilizer, a light-resistant stabilizer, a fluorescent whitening agent, a foaming agent, a pigment, a dye, a conductivity imparting agent, an antistatic agent, a moisture permeability improver, a water repellent agent, an oil repellent agent, a hollow foamed body, a flame retardant, a water absorbent, a moisture absorbent, a deodorant, a foam stabilizer, an antiblocking agent, a hydrolysis inhibitor, or the like can be used. These additives may be used alone or in a combination of two or more kinds thereof.

It is essential that the skin layer (iii) is formed of the aqueous urethane resin composition (Z) containing the urethane resin (X) and the aqueous medium (Y), and the urethane resin (X) is a reaction product obtained by using a polyol (b1), a reactive silicone (b2) having a functional group which reacts with an isocyanate group and having a number average molecular weight of <NUM>,<NUM> or more, and a polyisocyanate (b3) as essential raw materials. The skin layer (iii) generally has a problem in adhesiveness to the intermediate layer because silicone is introduced into the urethane resin (X), but by being used in a combination with the specific intermediate layer (ii) in the present invention, excellent peeling strength as a synthetic leather can be obtained.

The urethane resin (X) can be dispersed in the aqueous medium (Y) described later, and for example, a urethane resin having a hydrophilic group such as an anionic group, a cationic group, or a nonionic group; a urethane resin forcibly dispersed in the aqueous medium (Y) with an emulsifier; or the like can be used. These urethane resins (X) may be used alone or in a combination of two or more kinds thereof. Among them, from the viewpoint of production stability, a urethane resin having a hydrophilic group is preferably used, and from the viewpoint that far superior abrasion resistance and hydrolysis resistance are obtained, a urethane resin having an anionic group is more preferably used.

Examples of a method for obtaining the urethane resin having an anionic group include a method in which one or more kinds of compounds selected from the group consisting of a glycol compound having a carboxyl group and a compound having a sulfonyl group are used as a raw material.

As the glycol compound having a carboxyl group, for example, <NUM>,<NUM>'-dimethylolpropionic acid, <NUM>,<NUM>'-dimethylolbutanoic acid, <NUM>,<NUM>'-dimethylolbutyric acid, <NUM>,<NUM>'-dimethylolpropionic acid, <NUM>,<NUM>'-valeric acid, or the like can be used. These compounds may be used alone or in a combination of two or more kinds thereof.

As the compound having a sulfonyl group, for example, <NUM>,<NUM>-diaminobutanesulfonic acid, <NUM>,<NUM>-diamino-<NUM>-toluenesulfonic acid, <NUM>,<NUM>-diaminobenzenesulfonic acid, N-(<NUM>-aminoethyl)-<NUM>-aminoethylsulfonic acid, or the like can be used. These compounds may be used alone or in a combination of two or more kinds thereof.

The carboxyl group and the sulfonyl group may be partially or entirely neutralized with a basic compound in the aqueous urethane resin composition. As the basic compound, for example, organic amine such as ammonia, triethylamine, pyridine, and morpholine; alkanolamine such as monoethanolamine and dimethylethanolamine; a metal base compound containing sodium, potassium, lithium, calcium, or the like; or the like can be used.

When a urethane resin having an anionic group (hereinafter, abbreviated as an "anionic urethane resin") is used as the urethane resin (X), from the viewpoint that a hydrophilic group promotes hydrolysis and thus far superior hydrolysis resistance is obtained and the viewpoint that far superior peeling strength is obtained, the acid value of the anionic urethane resin is preferably <NUM> mgKOH/g or less, more preferably <NUM> to <NUM> mgKOH/g, still more preferably <NUM> to <NUM> mgKOH/g, and particularly preferably <NUM> to <NUM> mgKOH/g. A method for measuring the acid value of the anionic urethane resin will be described in Example described later. Moreover, examples of a method of adjusting the acid value of the anionic urethane resin include a method of adjusting the use amount of the glycol compound having a carboxyl group and the compound having a sulfonyl group, which provide an anionic group.

From the viewpoint that far superior hydrolysis resistance and peeling strength are obtained, the use amount of the glycol compound having a carboxyl group and the compound having a sulfonyl group is preferably <NUM>% to <NUM>% by mass, more preferably <NUM>% to <NUM>% by mass, and still more preferably <NUM>% to <NUM>% by mass in the total mass of the raw materials constituting the urethane resin (X).

Examples of a method for obtaining the urethane resin having a cationic group include a method in which one or more kinds of compounds having an amino group are used as a raw material.

As the compound having an amino group, for example, a compound having a primary or secondary amino group such as triethylenetetramine and diethylenetriamine; a compound having a tertiary amino group such as N-alkyldialkanolamine, for example, N-methyldiethanolamine and N-ethyldiethanolamine and N-alkyldiaminoalkylamine, for example, N-methyldiaminoethylamine and N-ethyldiaminoethylamine; or the like can be used. These compounds may be used alone or in a combination of two or more kinds thereof.

Examples of a method for obtaining the urethane resin having a nonionic group include a method in which one or more kinds of compounds having an oxyethylene structure are used as a raw material.

As the compound having an oxyethylene structure, for example, polyether polyol having an oxyethylene structure, such as polyoxyethylene glycol, polyoxyethylene polyoxypropylene glycol, and polyoxyethylene polyoxytetramethylene glycol can be used. These compounds may be used alone or in a combination of two or more kinds thereof.

As the emulsifier which can be used for obtaining the urethane resin forcibly dispersed in the aqueous medium (Y), for example, a nonionic emulsifier such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrylphenyl ether, polyoxyethylene sorbitol tetraoleate, and a polyoxyethylene-polyoxypropylene copolymer; an anionic emulsifier such as fatty acid salt, for example, sodium oleate, alkyl sulfate ester salt, alkyl benzene sulfonic acid salt, alkylsulfosuccinic acid salt, naphthalene sulfonic acid salt, polyoxyethylene alkyl sulfuric acid salt, alkanesulfonate sodium salt, and alkyl diphenyl ether sulfonic acid sodium salt; a cationic emulsifier such as alkyl amine salt, alkyltrimethyl ammonium salt, and alkyldimethylbenzyl ammonium salt; or the like can be used. These emulsifiers may be used alone or in a combination of two or more kinds thereof.

The urethane resin (X) is a reaction product of a polyol (b1), a reactive silicone (b2) having a functional group which reacts with an isocyanate group and having a number average molecular weight of <NUM>,<NUM> or more, and a polyisocyanate (b3).

As the polyol (b1), for example, polyether polyol, polyester polyol, polyacryl polyol, polycarbonate polyol, polybutadiene polyol, or the like can be used. The polyol may be used alone or in a combination of two or more kinds thereof. As the polyol (b1), from the viewpoint that far superior abrasion resistance, hydrolysis resistance, and peeling strength are obtained, polyether polyol and/or polycarbonate polyol is preferably used and polytetramethylene glycol and/or polycarbonate polyol is more preferably used. Moreover, as the polycarbonate polyol, for the same reason, polycarbonate polyol obtained by using <NUM>,<NUM>-hexanediol and/or <NUM>,<NUM>-butanediol as a raw material is preferably used and polycarbonate polyol obtained by using <NUM>,<NUM>-hexanediol and <NUM>,<NUM>-butanediol as raw materials is more preferably used. When a urethane resin having a nonionic group is used as the urethane resin (X), a compound other than the compound having the oxyethylene structure is used as the polyol (b1).

From the viewpoint of the mechanical strength of the obtained film, the number-average molecular weight of the polyol (b1) is preferably <NUM> to <NUM>,<NUM> and more preferably <NUM> to <NUM>,<NUM>. Moreover, the number-average molecular weight of the polyol (b1) indicates a value measured in the same manner as the number-average molecular weight of the polyol (a1).

From the viewpoint of the mechanical strength of the film, the amount of the polyol (b1) used is preferably <NUM>% to <NUM>% by mass, more preferably <NUM>% to <NUM>% by mass, and still more preferably <NUM>% to <NUM>% by mass in the total mass of the raw materials constituting the urethane resin (X).

The polyol (b1) may be used in a combination with a chain extender (b1-<NUM>) having a number-average molecular weight of <NUM> to <NUM>, if necessary. Moreover, the number-average molecular weight of the chain extender (b1-<NUM>) indicates a value obtained by measuring in the same manner as the number-average molecular weight of the polyol (b1).

As the chain extender (b1-<NUM>), for example, a chain extender having a hydroxyl group, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, <NUM>,<NUM>-propanediol, <NUM>,<NUM>-butanediol, <NUM>,<NUM>-butanediol, hexamethylene glycol, saccharose, methylene glycol, glycerin, sorbitol, bisphenol A, <NUM>,<NUM>'-dihydroxydiphenyl, <NUM>,<NUM>'-dihydroxydiphenyl ether, and trimethylolpropane; a chain extender having an amino group, such as ethylenediamine, <NUM>,<NUM>-propanediamine, <NUM>,<NUM>-hexamethylenediamine, piperazine, <NUM>,<NUM>-dimethylpiperazine, isophoronediamine, <NUM>,<NUM>-cyclohexanediamine, <NUM>,<NUM>-cyclohexanediamine, <NUM>,<NUM>-cyclohexanediamine, <NUM>,<NUM>'-dicyclohexylmethanediamine, <NUM>,<NUM>'-dimethyl-<NUM>,<NUM>'-dicyclohexylmethanediamine, <NUM>,<NUM>-cyclohexanediamine, and hydrazine; or the like can be used. These chain extenders may be used alone or in a combination of two or more kinds thereof. Among them, from the viewpoint of durability such as hydrolysis resistance and heat resistance, a chain extender having an amino group is preferably used and one or more kinds of chain extenders selected from the group consisting of ethylenediamine, isophoronediamine, and piperazine are more preferably used.

When the chain extender (b1-<NUM>) is used, the amount of the chain extender used is preferably <NUM>% to <NUM>% by mass, more preferably <NUM>% to <NUM>% by mass, and still more preferably <NUM>% to <NUM>% by mass in the total mass of the raw materials constituting the urethane resin (X), from the viewpoint of durability such as hydrolysis resistance and heat resistance.

It is essential that the reactive silicone (b2) has a functional group which reacts with an isocyanate group, in order to obtain excellent abrasion resistance and hydrolysis resistance by being incorporated in the urethane resin (A).

From the viewpoint that high slipperiness can be imparted and far superior abrasion resistance, hydrolysis resistance, and peeling strength are obtained, the number-average molecular weight of the reactive silicone (b2) is preferably <NUM>,<NUM> to <NUM>,<NUM>, still more preferably <NUM>,<NUM> to <NUM>,<NUM>, and even more preferably <NUM>,<NUM> to <NUM>,<NUM>. Moreover, the number-average molecular weight of the reactive silicone (b2) indicates a value obtained by measuring in the same manner as that of the polyol (a1).

As the reactive silicone (b2), for example, one-end diol-type reactive silicone, one-end monool-type reactive silicone, one-end diamine-type reactive silicone, and one-end monoamine-type reactive silicone, which are represented by Formula (<NUM>); both-end diol-type reactive silicone, both-end diamine-type reactive silicone, both-end dimercapto-type reactive silicone, and both-end disilanol-type reactive silicone, which are represented by Formula (<NUM>); side-chain monoamine-type reactive silicone represented by Formula (<NUM>); or the like can be used. The reactive silicone may be used alone or in a combination of two or more kinds thereof. <CHM>
(In Formula (<NUM>), R<NUM> and R<NUM> each independently represent an alkyl group having <NUM> to <NUM> carbon atoms, X represents a structure represented by any one of Formulae (X-<NUM>) to (X-<NUM>), and n represents an integer of <NUM> to <NUM>. )
<CHM>
(In Formulae (X-<NUM>) and (X-<NUM>), R<NUM> and R<NUM> each independently represent an alkylene group having <NUM> to <NUM> carbon atoms, and R<NUM> represents a hydrogen atom or an alkyl group having <NUM> to <NUM> carbon atoms. )
<CHM>
(In Formulae (X-<NUM>) and (X-<NUM>), R<NUM> represents an alkylene group having <NUM> to <NUM> carbon atoms, and R<NUM> represents a hydrogen atom or an alkyl group having <NUM> to <NUM> carbon atoms. )
<CHM>
(In Formulae (X-<NUM>) and (X-<NUM>), R<NUM> represents an alkylene group having <NUM> to <NUM> carbon atoms, and R<NUM> represents a hydrogen atom or an alkyl group having <NUM> to <NUM> carbon atoms. )
<CHM>
(In Formulae (X-<NUM>) and (X-<NUM>), R<NUM> and R<NUM> each independently represent an alkylene group having <NUM> to <NUM> carbon atoms, and R<NUM> represents a hydrogen atom or an alkyl group having <NUM> to <NUM> carbon atoms.

<NUM>]     -R<NUM>-O-R<NUM>-OH (X-<NUM>) -R<NUM>-O-R<NUM>-NH<NUM> (X-<NUM>).

(In Formulae (X-<NUM>) and (X-<NUM>), R<NUM> and R<NUM> each independently represent an alkylene group having <NUM> to <NUM> carbon atoms.

<NUM>]      -R<NUM>-OH (X-<NUM>) -R<NUM>-NH<NUM> (X-<NUM>).

(In Formulae (X-<NUM>) and (X-<NUM>), R<NUM> represents an alkylene group having <NUM> to <NUM> carbon atoms. )
<CHM>
(In Formula (<NUM>), R<NUM> represents an alkyl group having <NUM> to <NUM> carbon atoms, Y represents a structure represented by any one of Formulae (Y-<NUM>) to (Y-<NUM>), and n represents an integer of <NUM> to <NUM>.

<NUM>]     -R<NUM>-OH (Y-<NUM>) -R<NUM>-NH<NUM> (Y-<NUM>) -R<NUM>-SH (Y-<NUM>).

(In Formulae (Y-<NUM>) to (Y-<NUM>), R<NUM> represents an alkylene group having <NUM> to <NUM> carbon atoms.

<NUM>]     -R<NUM>-O-R<NUM>-OH (Y-<NUM>).

(In Formula (Y-<NUM>), R<NUM> and R<NUM> each independently represent an alkylene group having <NUM> to <NUM> carbon atoms. )
<CHM>
(In Formula (<NUM>), R<NUM> and R<NUM> each represent an alkyl group having <NUM> to <NUM> carbon atoms, Z represents a structure represented by Formula (Z-<NUM>) or (Z-<NUM>), m represents an integer of <NUM> to <NUM>, and n represents an integer of <NUM> to <NUM>.

<NUM>]     -R<NUM>-NH<NUM> (Z-<NUM>).

(In Formula (Z-<NUM>), R<NUM> represents an alkylene group having <NUM> to <NUM> carbon atoms.

<CHM>
(In Formula (Z-<NUM>), R<NUM> and R<NUM> each independently represent an alkylene group having <NUM> to <NUM> carbon atoms.

As the reactive silicone (b2), for example, "SILAPLANE FM-<NUM>", "SILAPLANE FM-<NUM>", "SILAPLANE FM-<NUM>", "SILAPLANE FM-<NUM>", "SILAPLANE FM-<NUM>", "SILAPLANE FM-<NUM>", "SILAPLANE FM-DA21", and "SILAPLANE FM-DA26", which are manufactured by JNC Corporation; "X-<NUM>-176GX-A" and "X-<NUM>-176F", which are manufactured by Shin-Etsu Chemical Co. ; and the like can be obtained as a commercial product.

As the reactive silicone (b2), from the viewpoint that higher slipperiness is imparted due to introduction of a silicone chain into a side chain of the urethane resin (X) and far superior abrasion resistance, hydrolysis resistance, and peeling strength are obtained, reactive silicone represented by Formula (<NUM>) is preferably used, reactive silicone represented by Formula (<NUM>) where X is one or more kinds selected from the group consisting of Formulae (X-<NUM>), (X-<NUM>), and (X-<NUM>) is more preferably used, and reactive silicone represented by Formula (<NUM>) where X represents Formula (X-<NUM>) and/or (X-<NUM>) is still more preferably used. Moreover, it is preferable to use reactive silicone in which in Formula (<NUM>), R<NUM> and R<NUM> are each an alkyl group having <NUM> to <NUM> carbon atoms and n is an integer of <NUM> to <NUM>, and in Formulae (X-<NUM>) and (X-<NUM>), R<NUM> and R<NUM> are each an alkylene group having <NUM> to <NUM> carbon atoms and R<NUM> is an alkyl group having <NUM> to <NUM> carbon atoms.

From the viewpoint that far superior abrasion resistance, hydrolysis resistance, and peeling strength are obtained, the amount of the reactive silicone (b2) used is preferably <NUM>% to <NUM>% by mass, more preferably <NUM>% to <NUM>% by mass, and still more preferably <NUM>% to <NUM>% by mass in the total mass of the raw materials constituting the urethane resin (A).

As the polyisocyanate (b3), for example, aromatic polyisocyanate such as phenylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, and carbodiimidated diphenylmethane polyisocyanate; aliphatic polyisocyanate and/or alicyclic polyisocyanate such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate; or the like can be used. The polyisocyanate may be used alone or in a combination of two or more kinds thereof. Among them, from the viewpoint of light discoloration resistance, aliphatic polyisocyanate and/or alicyclic polyisocyanate is preferably used and one or more kinds of polyisocyanate selected from the group consisting of hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate are more preferably used.

From the viewpoint of production stability and mechanical properties of the obtained film, the amount of the polyisocyanate (b3) used is preferably <NUM>% to <NUM>% by mass, more preferably <NUM>% to <NUM>% by mass, and still more preferably <NUM>% to <NUM>% by mass in the total mass of the raw materials constituting the urethane resin (X).

Examples of a method for producing the urethane resin (X) include a method in which the polyol (b1), the raw material used for producing the urethane resin having a hydrophilic group, the reactive silicone (b2), the polyisocyanate (b3), and if necessary, the chain extender (b1-<NUM>) are charged at once and reacted with one another. The reaction may be carried out, for example, at <NUM> to <NUM> for <NUM> to <NUM> hours.

A molar ratio [isocyanate group/total of functional groups that react with isocyanate groups] of the isocyanate group of the polyisocyanate (b3) to the total of the hydroxyl group of the polyol (b1), the hydroxyl group and the amino group of the chain extender (b1-<NUM>), the functional group which reacts with the isocyanate group of the raw material used for producing the urethane resin having a hydrophilic group, and the functional group which reacts with the isocyanate group of the reactive silicone (b2) in production of the urethane resin (X) is preferably <NUM> to <NUM> and more preferably <NUM> to <NUM>.

When the urethane resin (X) is produced, the isocyanate groups remaining in the urethane resin (X) are preferably deactivated. When the isocyanate groups are deactivated, alcohol having one hydroxyl group, such as methanol, is preferably used. The amount of the alcohol used is preferably <NUM> to <NUM> parts by mass with respect to <NUM> parts by mass of the urethane resin (X).

Furthermore, when the urethane resin (X) is produced, an organic solvent may be used. As the organic solvent, for example, a ketone compound such as acetone and methyl ethyl ketone; an ether compound such as tetrahydrofuran and dioxane; an acetate ester compound such as ethyl acetate and butyl acetate; a nitrile compound such as acetonitrile; an amide compound such as a dimethylformamide and N-methylpyrrolidone; or the like can be used. These organic solvents may be used alone or in a combination of two or more kinds thereof. Moreover, the organic solvent is preferably removed by a distillation method or the like when the aqueous urethane resin composition is obtained.

As the aqueous medium (Y), the same aqueous medium as the aqueous medium (B) used for forming the intermediate layer (ii) can be used. Among them, from the viewpoint of safety and reduction in an environmental load, only water or a mixture of water and an organic solvent miscible with water is preferably used and only water is more preferably used.

From the viewpoint of workability, a mass ratio [(X) / (Y)] of the urethane resin (X) to the aqueous medium (Y) is preferably <NUM>/<NUM> to <NUM>/<NUM> and more preferably <NUM>/<NUM> to <NUM>/<NUM>.

The aqueous urethane resin composition (Z) of the present invention contains the urethane resin (X) and the aqueous medium (Y), but may contain other additives, if necessary.

As the other additives, for example, an emulsifier, a neutralizer, a thickener, a urethanization catalyst, a crosslinking agent, a foaming agent, a pigment, a dye, an oil repellent agent, a hollow foamed body, a flame retardant, an antifoaming agent, a leveling agent, an antiblocking agent, or the like can be used. These additives may be used alone or in a combination of two or more kinds thereof.

Next, a method for producing the synthetic leather of the present invention will be described.

Examples of a method for producing the synthetic leather include a method in which the aqueous urethane resin composition (Z) is applied on a release-treated substrate and subjected to drying and processing to obtain the skin layer (iii), then the aqueous urethane resin composition (C) is applied on the skin layer (iii) and dried to form an adhesive layer (ii), and the adhesive layer (ii) is bonded to the base fabric (i).

Examples of a method of applying the aqueous urethane resin compositions (C) and (Z) of the present invention include a method in which an applicator, a roll coater, a spray coater, a T-die coater, a knife coater, a comma coater, or the like is used.

Examples of a method of drying the aqueous urethane resin compositions (C) and (Z) include a method of performing drying at <NUM> to <NUM> for <NUM> to <NUM> minutes. The thicknesses of the obtained intermediate layer (ii) and skin layer (iii) are appropriately determined according to the application in which the synthetic leather is used and are, for example, <NUM> to <NUM>, respectively.

After the synthetic leather is produced, if necessary, aging may be performed, for example, at <NUM> to <NUM> for <NUM> to <NUM> days.

As described above, the synthetic leather of the present invention has excellent environmental compatibility because both the intermediate layer and the skin layer are formed of the aqueous urethane resin composition, and has excellent abrasion resistance, peeling strength, hydrolysis resistance, and light resistance.

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, under a nitrogen stream, <NUM> parts by mass of polytetramethylene glycol (number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "PTMG1000"), <NUM> parts by mass of dimethylolpropionic acid (hereinafter, abbreviated as "DMPA"), and <NUM> parts by mass of methyl ethyl ketone were added, and after being uniformly mixed, <NUM> parts by mass of toluene diisocyanate (hereinafter, abbreviated as "TDI") was added and then <NUM> parts by mass of dibutyltin dilaurate was added, followed by a reaction at <NUM> for about <NUM> hours. Next, <NUM> parts by mass of <NUM>,<NUM>-butanediol (hereinafter, abbreviated as "<NUM>,<NUM>-BG") was added thereto, the resultant was reacted at <NUM> for about <NUM> hour, and the reaction was completed to obtain a methyl ethyl ketone solution of a urethane polymer. Subsequently, <NUM> parts by mass of N,N-dimethylethanolamine was added to the methyl ethyl ketone solution of the urethane polymer obtained by the method, and after a carboxyl group in the urethane polymer was neutralized, <NUM> parts by mass of ion-exchanged water was added thereto and then methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (nonvolatile content; <NUM>% by mass, concentration of anionic group (carboxyl group, the same shall apply hereinafter); <NUM> mmol/g) (PUD-<NUM> for intermediate layer).

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, under a nitrogen stream, <NUM> parts by mass of polycarbonate diol ("DURANOL T5652" manufactured by Asahi Kasei Chemicals Corporation, number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "PC"), <NUM> parts by mass of DMPA, and <NUM> parts by mass of methyl ethyl ketone were added, and after being uniformly mixed, <NUM> parts by mass of TDI was added and then <NUM> parts by mass of dibutyltin dilaurate was added, followed by a reaction at <NUM> for about <NUM> hours. Next, <NUM> parts by mass of <NUM>,<NUM>-BG was added thereto, the resultant was reacted at <NUM> for about <NUM> hour, and the reaction was completed to obtain a methyl ethyl ketone solution of a urethane polymer. Subsequently, <NUM> parts by mass of triethylamine was added to the methyl ethyl ketone solution of the urethane polymer obtained by the method, and after a carboxyl group in the urethane polymer was neutralized, <NUM> parts by mass of ion-exchanged water was added thereto and then methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (nonvolatile content; <NUM>% by mass, concentration of anionic group; <NUM> mmol/g) (PUD-<NUM> for intermediate layer).

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, under a nitrogen stream, <NUM> parts by mass of polypropylene glycol (number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "PPG2000"), <NUM> parts by mass of <NUM>,<NUM>-butanediol (hereinafter, abbreviated as "<NUM>,<NUM>-BG"), <NUM> parts by mass of DMPA, and <NUM> parts by mass of methyl ethyl ketone were added, and after being uniformly mixed, <NUM> parts by mass of TDI was added and then <NUM> parts by mass of dibutyltin dilaurate was added, followed by a reaction at <NUM> for about <NUM> hours. Next, <NUM> parts by mass of <NUM>,<NUM>-BG was added thereto, the resultant was reacted at <NUM> for about <NUM> hour, and the reaction was completed to obtain a methyl ethyl ketone solution of a urethane polymer. Subsequently, <NUM> parts by mass of N,N-dimethylethanolamine was added to the methyl ethyl ketone solution of the urethane polymer obtained by the method, and after a carboxyl group in the urethane polymer was neutralized, <NUM> parts by mass of ion-exchanged water was added thereto and then methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (nonvolatile content; <NUM>% by mass, concentration of anionic group; <NUM> mmol/g) (PUD-<NUM> for intermediate layer).

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, under a nitrogen stream, <NUM> parts by mass of polytetramethylene glycol (number-average molecular weight: <NUM>,<NUM>, hereinafter, "PTMG2000"), <NUM> parts by mass of ethylene glycol (hereinafter, abbreviated as "EG"), <NUM> parts by mass of DMPA, and <NUM> parts by mass of methyl ethyl ketone were added, and after being uniformly mixed, <NUM> parts by mass of TDI was added and then <NUM> parts by mass of dibutyltin dilaurate was added, followed by a reaction at <NUM> for about <NUM> hours. Next, <NUM> parts by mass of <NUM>,<NUM>-BG was added thereto, the resultant was reacted at <NUM> for about <NUM> hour, and the reaction was completed to obtain a methyl ethyl ketone solution of a urethane polymer. Subsequently, <NUM> parts by mass of triethylamine was added to the methyl ethyl ketone solution of the urethane polymer obtained by the method, and after a carboxyl group in the urethane polymer was neutralized, <NUM> parts by mass of ion-exchanged water was added thereto and then methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (nonvolatile content; <NUM>% by mass, concentration of anionic group; <NUM> mmol/g) (PUD-<NUM> for intermediate layer).

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, under a nitrogen stream, <NUM> parts by mass of polycarbonate diol ("ETERNACOLL UH-<NUM>" manufactured by UBE INDUSTRIES, LTD. , number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "PC-<NUM>"), <NUM> parts by mass of both-end diol-type reactive silicone ("SILAPLANE FM-<NUM>" manufactured by JNC Corporation, number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "both-end diol-type Si-<NUM>"), <NUM> parts by mass of dimethylolpropionic acid (hereinafter, abbreviated as "DMPA"), and <NUM> parts by mass of methyl ethyl ketone were added, and after being uniformly mixed, <NUM> parts by mass of dicyclohexylmethane diisocyanate (hereinafter, abbreviated as "H<NUM>MDI") was added and then <NUM> parts by mass of dibutyltin dilaurate was added. A reaction was performed at <NUM> for about <NUM> hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at a molecular terminal. Subsequently, <NUM> parts by mass of triethylamine was added to the obtained methyl ethyl ketone solution of the urethane prepolymer, and after a carboxyl group in the urethane prepolymer was neutralized, <NUM> parts by mass of ion-exchanged water was added thereto and then <NUM> parts by mass of ethylenediamine (hereinafter, abbreviated as "EDA") was added thereto, followed by a reaction. After completion of the reaction, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (PUD-<NUM> for skin layer) (nonvolatile content; <NUM>% by mass, acid value; <NUM> KOHmg/g).

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen reflux tube, under a nitrogen stream, <NUM> parts by mass of polycarbonate diol ("DURANOL T5652" manufactured by Asahi Kasei Chemicals Corporation, number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "PC-<NUM>"), <NUM> parts by mass of one-end diol-type reactive silicone ("X-<NUM>-176GX-A" manufactured by Shin-Etsu Chemical Co. , number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "one-end diol-type Si-<NUM>"), <NUM> parts by mass of DMPA, and <NUM> parts by mass of methyl ethyl ketone were added, and after being uniformly mixed, <NUM> parts by mass of isophorone diisocyanate (hereinafter, abbreviated as "IPDI") was added and then <NUM> parts by mass of dibutyltin dilaurate was added. A reaction was performed at <NUM> for about <NUM> hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at a molecular terminal. Subsequently, <NUM> parts by mass of triethylamine was added to the obtained methyl ethyl ketone solution of the urethane prepolymer, and after a carboxyl group in the urethane prepolymer was neutralized, <NUM> parts by mass of ion-exchanged water was added thereto and then <NUM> parts by mass of piperazine (hereinafter, abbreviated as "PZ") was added thereto, followed by a reaction. After completion of the reaction, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (PUD-<NUM> for skin layer) (nonvolatile content; <NUM>% by mass, acid value; <NUM> KOHmg/g).

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen reflux tube, under a nitrogen stream, <NUM> parts by mass of polycarbonate diol ("DURANOL T4692" manufactured by Asahi Kasei Chemicals Corporation, number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "PC-<NUM>"), <NUM> parts by mass of one-end diol-type reactive silicone ("SILAPLANE FM-DA21" manufactured by JNC Corporation, number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "one-end diol-type Si-<NUM>"), <NUM> parts by mass of DMPA, and <NUM> parts by mass of methyl ethyl ketone were added, and after being uniformly mixed, <NUM> parts by mass of H<NUM>MDI was added and then <NUM> parts by mass of dibutyltin dilaurate was added. A reaction was performed at <NUM> for about <NUM> hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at a molecular terminal. Subsequently, <NUM> parts by mass of triethylamine was added to the obtained methyl ethyl ketone solution of the urethane prepolymer, and after a carboxyl group in the urethane prepolymer was neutralized, <NUM> parts by mass of ion-exchanged water was added thereto and then <NUM> parts by mass of Isophoronediamine (hereinafter, abbreviated as "IPDA") was added thereto, followed by a reaction. After completion of the reaction, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (PUD-<NUM> for skin layer) (nonvolatile content; <NUM>% by mass, acid value; <NUM> KOHmg/g).

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen reflux tube, under a nitrogen stream, <NUM> parts by mass of PC-<NUM>, <NUM> parts by mass of polytetramethylene glycol (number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "PTMF1000"), <NUM> parts by mass of one-end diol-type reactive silicone ("X-<NUM>-176F" manufactured by Shin-Etsu Chemical Co. , number-average molecular weight: <NUM>,<NUM>, hereinafter, abbreviated as "one-end diol-type Si-<NUM>"), <NUM> parts by mass of DMPA, and <NUM> parts by mass of methyl ethyl ketone were added, and after being uniformly mixed, <NUM> parts by mass of IPDI was added and then <NUM> parts by mass of dibutyltin dilaurate was added. A reaction was performed at <NUM> for about <NUM> hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at a molecular terminal. Subsequently, <NUM> parts by mass of triethylamine was added to the obtained methyl ethyl ketone solution of the urethane prepolymer, and after a carboxyl group in the urethane prepolymer was neutralized, <NUM> parts by mass of ion-exchanged water was added thereto and then <NUM> parts by mass of EDA was added thereto, followed by a reaction. After completion of the reaction, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (PUD-<NUM> for skin layer) (nonvolatile content; <NUM>% by mass, acid value; <NUM> KOHmg/g).

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, under a nitrogen stream, <NUM> parts by mass of PTMG1000, <NUM> parts by mass of DMPA, and <NUM> parts by mass of methyl ethyl ketone were added, and after being uniformly mixed, <NUM> parts by mass of isophorone diisocyanate (hereinafter, abbreviated as "IPDI") was added and then <NUM> parts by mass of dibutyltin dilaurate was added, followed by a reaction at <NUM> for about <NUM> hours. Next, <NUM> parts by mass of <NUM>,<NUM>-BG was added thereto, the resultant was reacted at <NUM> for about <NUM> hour, and the reaction was completed to obtain a methyl ethyl ketone solution of a urethane polymer. Subsequently, <NUM> parts by mass of N,N-dimethylethanolamine was added to the methyl ethyl ketone solution of the urethane polymer obtained by the method, and after a carboxyl group in the urethane polymer was neutralized, <NUM> parts by mass of ion-exchanged water was added thereto and then methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (nonvolatile content; <NUM>% by mass, concentration of anionic group; <NUM> mmol/g) (PUD'-<NUM> for intermediate layer).

An aqueous urethane resin composition (contains a urethane resin obtained by reacting PC-<NUM>, DMPA, IPDA, and IPDI with one another, and water, nonvolatile content; <NUM>% by mass, acid value; <NUM> KOHmg/g) was set as PUD'-<NUM> for a skin layer.

Blended liquid including <NUM> parts by mass of PUD-<NUM> for a skin layer, <NUM> parts by mass of a water-dispersible black pigment ("DILAC HS-<NUM>" manufactured by DIC Corporation), and <NUM> part by mass of an associative thickener ("HYDRAN ASSISTER T10" manufactured by DIC Corporation) was applied on flat release paper ("DN-TP-155T" manufactured by AJINOMOTO CO. ) so that a film thickness after drying was <NUM>, and dried at <NUM> for <NUM> minutes and further at <NUM> for <NUM> minutes.

Subsequently, blended liquid including <NUM> parts by mass of PUD-<NUM> for an intermediate layer obtained in Synthesis Example described above, <NUM> part by mass of an associative thickener ("HYDRAN ASSISTER T10" manufactured by DIC Corporation), and <NUM> parts by mass of a polyisocyanate-based crosslinking agent ("HYDRAN ASSISTER C5" manufactured by DIC Corporation) was applied thereon so that a film thickness after drying was <NUM>, and dried at <NUM> for <NUM> minutes. Immediately after drying, the resultant was bonded to a non-woven fabric impregnated with a urethane resin, then heat-treated at <NUM> for <NUM> minutes, and aged at <NUM> for <NUM> days. Thereafter, the release paper was peeled off to obtain a synthetic leather.

Synthetic leathers were obtained in the same manner as in Example <NUM>, except that PUD for an intermediate layer used and/or PUD for a skin layer used was changed as shown in Tables <NUM> and <NUM>.

The number-average molecular weight of the polyol or the like used in Synthesis Examples was measured by a gel permeation column chromatography (GPC) method under the following conditions.

The peeling strength of each synthetic leather obtained in Examples and Comparative Examples was measured using Shimadzu autograph "AG-<NUM>" (manufactured by Shimadzu Corporation) under the conditions where a full scale is <NUM> and a head speed is <NUM>/min, and evaluated as follows.

Each synthetic leather obtained in Examples and Comparative Examples was allowed to stand for <NUM> weeks under the conditions where a temperature is <NUM> and humidity is <NUM>%. Thereafter, the peeling strength was measured in the same manner as in [Method for measuring peel strength], and a retention ratio of the peeling strength before and after being allowed to stand was calculated and evaluated as follows.

Each synthetic leather obtained in Examples and Comparative Examples was irradiated with light for <NUM> hours by using FADE METER "U48AU" (<NUM> and humidity of <NUM>%) manufactured by Suga Test Instruments Co. Thereafter, the synthetic leather was visually observed and evaluated as follows.

A plane abrasion test (JASO-M403-88B method, load; <NUM>, stroke; <NUM>) was performed on the obtained synthetic leather, the number of times until the surface of the synthetic leather was worn and the base fabric was observed was measured, and evaluation was performed as follows.

It was found that Examples <NUM> to <NUM>, which are the synthetic leathers of the present invention, are excellent in abrasion resistance, peeling strength, hydrolysis resistance, and light resistance.

On the other hand, Comparative Example <NUM> was an embodiment in which the skin layer was formed of an aqueous urethane resin containing a urethane resin into which silicone was not introduced, but abrasion resistance was extremely poor.

Comparative Example <NUM> was an embodiment in which the intermediate layer was formed of an aqueous urethane resin containing a urethane resin obtained by using alicyclic polyisocyanate as a raw material, but peeling strength was extremely poor.

Claim 1:
A synthetic leather comprising:
a base fabric (i);
an intermediate layer (ii); and
a skin layer (iii),
wherein the intermediate layer (ii) is formed of an aqueous urethane resin composition (C) containing a urethane resin (A) and an aqueous medium (B), and the urethane resin (A) is a reaction product of a polyol (a1) containing a polyol (a1-<NUM>) having an anionic group, an aromatic polyisocyanate (a2) and a chain extender (a3), and has an anionic group in a concentration of <NUM> mmol/g or less and
the skin layer (iii) is formed of an aqueous urethane resin composition (Z) containing a urethane resin (X) and an aqueous medium (Y), and the urethane resin (X) is a reaction product obtained by using a polyol (b1), a reactive silicone (b2) having a functional group which reacts with an isocyanate group, and a polyisocyanate (b3) as essential raw materials,
wherein the aromatic polyisocyanate (a2) is toluene diisocyanate, and
wherein the chain extender (a3) is an aliphatic polyol compound, and
wherein an amount of the reactive silicone (b2) used is <NUM>% to <NUM>% by mass in the total mass of the raw materials constituting the urethane resin (X), and
wherein the reactive silicone (b2) has a number average molecular weight of <NUM>,<NUM> or more.