Synthetic leather and method for manufacturing synthetic leather

Abstract

The present invention provides a synthetic leather having at least a base fabric, an adhesive layer, and a surface layer, the synthetic leather being characterized in that: the adhesive layer is formed from a mixture containing an aqueous urethane resin composition (A) and an aqueous urethane resin composition (B) other than the aqueous urethane resin composition (A); the aqueous urethane resin composition (A) contains a urethane resin (a1) having a urea bond concentration of 100 mmol / kg or less, an aqueous medium (a2), and an emulsifier (a3), the urethane resin (a1) having a polyol compound (a1-1) containing a nonionic polyol and an aromatic polyisocyanate compound (a1-2) as essential raw materials, and the aqueous medium (a2) being a mixture of the urethane resin (a1) and the polyol compound (a1-1). The weight average molecular weight of the aqueous urethane resin composition (B) is 100,000 or more. The synthetic leather is long in pot life and has excellent peel strength and light resistance.

Description

Technical Field

[0001] This invention relates to synthetic leather and a method for manufacturing synthetic leather. Background Technology

[0002] Waterborne urethane resin compositions have been studied in recent years as environmentally friendly materials due to their ability to reduce volatile organic compounds compared to conventional solvent-based urethane resin compositions. They are used in various applications such as artificial leather, synthetic leather, coatings, glove coatings and glove films, and adhesives.

[0003] In the application of adhesive layers for synthetic leather, a waterborne polyurethane resin adhesive is known, which comprises a waterborne polyurethane resin (PUD) with a softening temperature of less than 50°C and a melt viscosity of less than 60,000 Pa·s at 50°C and a polyisocyanate compound (for example, see Patent Document 1). However, the two-component adhesive, which combines the PUD main agent and the isocyanate crosslinking agent, has the problem of being difficult to process stably due to the short pot life of the compounding liquid.

[0004] Therefore, materials with a long service life, excellent peel strength, and light resistance are required.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2000-108289 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The problem to be solved by the present invention is to provide a synthetic leather with an adhesive layer having a long service life, excellent peel strength and light resistance, and a method for manufacturing the above-mentioned synthetic leather.

[0010] Methods for solving problems

[0011] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that by using a mixture of specific waterborne urethane resin compositions as an adhesive layer forming material, the above-mentioned problems can be solved, thus completing the present invention.

[0012] That is, the present invention relates to a synthetic leather having at least a base fabric (i), an adhesive layer (ii) and an epidermis layer (iii), characterized in that: the adhesive layer (ii) is formed from a mixture containing an aqueous urethane resin composition (A) and an aqueous urethane resin composition (B) other than the aqueous resin composition (A), wherein the aqueous urethane resin composition (A) contains urethane resin (a1), an aqueous medium (a2) and an emulsifier (a3), wherein the urethane resin (a1) uses a polyol compound (a1-1) containing a nonionic polyol and an aromatic polyisocyanate compound (a1-2) as essential raw materials, wherein the urea bond concentration in the urethane resin (a1) is less than 100 mmol / kg, and wherein the weight average molecular weight of the aqueous urethane resin composition (B) is more than 100,000.

[0013] Invention Effects

[0014] The synthetic leather of this invention has an adhesive layer with a long service life, excellent peel strength, and light resistance. Therefore, it can be used as a coating or adhesive, and is particularly suitable for adhesive layers of synthetic leather. Detailed Implementation

[0015] The synthetic leather of the present invention is characterized in that it has at least a base fabric (i), an adhesive layer (ii) and an epidermis layer (iii).

[0016] Examples of synthetic leather according to the present invention include the following structures (1) to (4).

[0017] Synthetic leather (1): base fabric (i), adhesive layer (ii), epidermis (iii)

[0018] Synthetic leather (2): base fabric (i), adhesive layer (ii), intermediate layer, epidermis (iii)

[0019] Synthetic leather (3): base fabric (i), porous layer, adhesive layer (ii), epidermis (iii)

[0020] Synthetic leather (4): base fabric (i), porous layer, adhesive layer (ii), intermediate layer, epidermis (iii)

[0021] Examples of the base fabrics (i) mentioned above include nonwoven fabrics, woven fabrics, and knitted fabrics made from polyester fibers, polyethylene fibers, nylon fibers, acrylic fibers, polyurethane fibers, acetate fibers, rayon fibers, polylactic acid fibers, cotton, linen, silk, wool, glass fibers, carbon fibers, and their blended fibers.

[0022] As the adhesive layer (ii) described above, an adhesive layer formed from a mixture containing an aqueous urethane resin composition (A) and an aqueous urethane resin composition (B) other than the aqueous resin composition (A) described above is used.

[0023] The above-mentioned waterborne urethane resin composition (A) uses a waterborne urethane resin composition containing urethane resin (a1), waterborne medium (a2) and emulsifier (a3).

[0024] The aforementioned urethane resin (a1) is an urethane resin that uses a polyol compound (a1-1) containing a nonionic polyol and an aromatic polyisocyanate compound (a1-2) as essential raw materials.

[0025] Examples of nonionic polyols include compounds having an oxyethylidene structure. These nonionic polyols can be used alone or in combination of two or more. Furthermore, from the perspective of obtaining synthetic leather with an adhesive layer that has a long service life, excellent peel strength, and good lightfastness, compounds having an oxyethylidene structure are preferred.

[0026] Examples of compounds with an oxyethylidene structure include polyethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, and polyethylene glycol dimethyl ether, among other polyether polyols with an oxyethylidene structure. These compounds can be used alone or in combination of two or more. Of these, polyethylene glycol and polyethylene glycol dimethyl ether are preferred from the perspective of obtaining synthetic leather with an adhesive layer that has a long service life, excellent peel strength, and good lightfastness.

[0027] The number-average molecular weight of the aforementioned nonionic polyols is preferably in the range of 200 to 10,000, more preferably in the range of 300 to 3,000, and even more preferably in the range of 300 to 2,000, from the perspective of obtaining synthetic leather with an adhesive layer having a long pot life, excellent peel strength, and excellent light resistance. It should be noted that, in this invention, the number-average molecular weight represents the value determined by gel permeation chromatography (GPC).

[0028] From the perspective of obtaining synthetic leather with an adhesive layer that has a long service life, excellent peel strength and light resistance, the proportion of the above-mentioned nonionic polyol used is preferably in the range of 1 to 30% by mass, and more preferably in the range of 2 to 10% by mass.

[0029] In addition, as the above-mentioned polyol compound (a1-1), polyols other than the above-mentioned nonionic polyols (hereinafter referred to as "other polyol compounds") may also be used as needed.

[0030] Other polyol compounds mentioned above include, for example, polyether polyols, polyester polyols, polyacrylic acid polyols, polycarbonate polyols, and polybutadiene polyols, in addition to the aforementioned nonionic polyols. These other polyol compounds can be used alone or in combination of two or more. Furthermore, from the perspective of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength, and excellent light resistance, polyether polyols, polyester polyols, and polycarbonate polyols are preferred.

[0031] The amount of the polyol compound (a1-1) used is preferably in the range of 40 to 90% by mass, and more preferably in the range of 50 to 80% by mass, from the perspective of obtaining synthetic leather with an adhesive layer that has a long service life, excellent peel strength and light resistance.

[0032] Examples of the aforementioned aromatic polyisocyanate compounds (a1-2) include phenylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, and carbodiimide diphenylmethane polyisocyanate. These aromatic polyisocyanate compounds can be used alone or in combination of two or more. Furthermore, from the perspective of obtaining synthetic leather with an adhesive layer possessing a long service life, excellent peel strength, and excellent light resistance, toluene diisocyanate is preferred.

[0033] The amount of the aromatic polyisocyanate compound (a1-2) used is preferably in the range of 5 to 60% by mass in the raw material of the urethane resin (a1), more preferably in the range of 10 to 50% by mass, from the perspective of obtaining synthetic leather with an adhesive layer that has a long service life, excellent peel strength and light resistance.

[0034] In addition, other polyisocyanate compounds (hereinafter referred to as "other polyisocyanate compounds") besides the above-mentioned aromatic polyisocyanate compounds (a1-2) may also be used as needed.

[0035] Other polyisocyanate compounds mentioned above include, for example, aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isoflurone diisocyanate, dicyclohexylmethane diisocyanate, phenyl diisocyanate, tetramethylphenyl diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate; and alicyclic diisocyanates such as norbornene diisocyanate, isoflurone diisocyanate, hydrogenated phenyl diisocyanate, and hydrogenated diphenylmethane diisocyanate. These other polyisocyanate compounds can be used alone or in combination of two or more.

[0036] The amount of the other polyisocyanate compounds used in the above-mentioned urethane resin (a1) raw materials is preferably in the range of 0.1% to 30% by mass, and more preferably in the range of 1% to 20% by mass.

[0037] The concentration of urea bonds in the above-mentioned urethane resin (a1) is 100 mmol / kg or less. From the viewpoint of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength and light resistance, it is preferably 50 mmol / kg or less, more preferably 30 mmol / kg or less, and particularly preferably 0 mmol / kg.

[0038] The average particle size of the above-mentioned urethane resin (a1) is preferably in the range of 0.01 to 1 μm, and more preferably in the range of 0.05 to 0.9 μm, from the viewpoint of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength and light resistance.

[0039] In addition to the polyol compound (a1-1) and the aromatic polyisocyanate compound (a1-2) mentioned above, chain extenders without amino groups may also be used as needed as required. In particular, from the viewpoint of obtaining synthetic leather with an adhesive layer having a long pot life, excellent peel strength and light resistance, chain extenders with hydroxyl groups are preferred.

[0040] Examples of hydroxyl-containing chain extenders include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, sucrose, methylene glycol, glycerol, sorbitol, bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, and trimethylolpropane. These chain extenders can be used alone or in combination of two or more. Among these, aliphatic polyol compounds are preferred from the viewpoint of easily suppressing discoloration and obtaining superior lightfastness.

[0041] There are no particular limitations on the method for manufacturing the above-mentioned urethane resin (a1), and it can be manufactured by any method. For example, it can be manufactured by reacting all the reactants containing the above-mentioned polyol compound (a1-1) and the above-mentioned aromatic polyisocyanate compound (a1-2) in a batch, or it can be manufactured by reacting the reactants sequentially. Preferably, these reactions are carried out at a temperature of 50 to 100°C for 3 to 10 hours.

[0042] The molar ratio of the total number of hydroxyl groups in the polyol compound (a1-1) and the chain extender to the number of isocyanate groups in the aromatic polyisocyanate compound (a1-2) [(isocyanate group) / (hydroxyl group)] is preferably in the range of 0.80 to 1.00, more preferably in the range of 0.85 to 0.98.

[0043] In addition, organic solvents can also be used when manufacturing the above-mentioned urethane resin (a1), but from the point of view of environmental friendliness, the reaction between the above-mentioned polyol compound (a1-1) and the above-mentioned aromatic polyisocyanate compound (a1-2) is preferably carried out in a solvent-free environment.

[0044] Examples of organic solvents that can be used include ketone compounds such as acetone and methyl ethyl ketone; ether compounds such as tetrahydrofuran and dioxane; acetate compounds such as ethyl acetate and butyl acetate; nitrile compounds such as acetonitrile; and amide compounds such as dimethylformamide and N-methylpyrrolidone. These organic solvents can be used alone or in combination of two or more. It should be noted that the aforementioned organic solvents are preferably removed by distillation or the like when obtaining the aqueous urethane resin composition.

[0045] From the perspective of obtaining synthetic leather with an adhesive layer having a long pot life, excellent peel strength, and excellent light resistance, the weight-average molecular weight of the above-mentioned urethane resin (a1) is preferably in the range of 2,000 to 150,000, more preferably in the range of 4,000 to 100,000, even more preferably in the range of 6,000 to 70,000, and particularly preferably in the range of 8,000 to 50,000. It should be noted that the weight-average molecular weight of the above-mentioned urethane resin (a1) is a value obtained by GPC measurement in the same manner as the number-average molecular weight of the above-mentioned polyol (a1-1).

[0046] Examples of aqueous media (a2) mentioned above include ion-exchanged water and distilled water. These aqueous media can be used alone or in combination of two or more.

[0047] The mass ratio of the above-mentioned urethane resin (a1) to the above-mentioned aqueous medium (a2) [(a1) / (a2)] is preferably in the range of 30 / 70 to 80 / 20, and more preferably in the range of 40 / 60 to 70 / 30, from the viewpoint of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength and light resistance.

[0048] Examples of emulsifiers (a3) ​​include nonionic emulsifiers such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrene phenyl ether, polyoxyethylene sorbitan tetraoleate, and polyethylene-polypropylene copolymer; anionic emulsifiers such as fatty acid salts, alkyl sulfates, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, polyoxyethylene alkyl sulfates, sodium alkyl sulfonates, and sodium alkyl diphenyl ether sulfonates; and cationic emulsifiers such as alkylamine salts, alkyl trimethylammonium salts, and alkyl dimethyl benzylammonium salts. These emulsifiers can be used alone or in combination of two or more. Furthermore, from the perspective of obtaining synthetic leather with an adhesive layer that has a long pot life, excellent peel strength, and excellent light resistance, anionic emulsifiers are preferred.

[0049] The amount of the emulsifier (a3) ​​used, from the perspective of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength and light resistance, is preferably 10 parts by mass or less, more preferably 0.5 to 5 parts by mass relative to 100 parts by mass of the urethane resin (a1).

[0050] The weight-average molecular weight of the above-mentioned waterborne urethane resin composition (A) is preferably in the range of 2,000 to 150,000, and more preferably in the range of 4,000 to 100,000, from the viewpoint of obtaining synthetic leather with an adhesive layer having a long pot life, excellent peel strength and light resistance.

[0051] There are no particular limitations on the method for manufacturing the above-mentioned aqueous urethane resin composition (A), and it can be manufactured by any method. For example, a method in which the above-mentioned urethane resin (a1), the above-mentioned aqueous medium (a2), and the emulsifier (a3) ​​are mixed can be cited.

[0052] As a method for mixing the above-mentioned urethane resin (a1), the above-mentioned aqueous medium (a2), and the above-mentioned emulsifier (a3), examples include methods using the following: a reaction vessel equipped with stirring blades; a kneader, a continuous kneader, a conical roller, a single-screw extruder, a twin-screw extruder, a three-screw extruder, a universal mixer, a Plastomill, a Bodeeda-type mixer, etc.; a rotary dispersion mixer, a homogenizer, a static mixer, a Filmix, an Ebara Milder, a Clearmix, an ULTRA-TURRAX, a Cavitron, a bio-mixer, etc.; an ultrasonic dispersion device; a device that does not have a movable part such as an in-line mixer, but can mix by the flow of the fluid itself, etc.

[0053] The above-mentioned waterborne urethane resin composition (A) may also contain other additives as needed.

[0054] Other additives mentioned above include, for example, surfactants, tackifiers, urethane esterification catalysts, fillers, pigments, dyes, flame retardants, leveling agents, and antiblocking agents. These additives can be used alone or in combination of two or more. It should be noted that, in manufacturing the above-mentioned urethane resin (a1), it is preferable that it does not contain organic solvents substantially, but organic solvents may be added as additives.

[0055] Examples of the aforementioned surfactants include nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrene phenyl ether, polyoxyethylene sorbitol tetraoleate, and polyethylene-polypropylene copolymer; anionic surfactants such as fatty acid salts, alkyl sulfate salts, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, polyoxyethylene alkyl sulfates, sodium alkyl sulfonates, and sodium alkyl diphenyl ether sulfonates; and cationic surfactants such as alkylamine salts, alkyl trimethylammonium salts, and alkyl dimethyl benzylammonium salts.

[0056] Examples of such tackifiers include associative and acid-based tackifiers.

[0057] Examples of carbamate catalysts include organotin and bismuth-based catalysts.

[0058] Examples of fillers mentioned above include calcium carbonate and silicon dioxide.

[0059] Examples of such pigments include carbon black.

[0060] Examples of such dyes include azo dyes.

[0061] Examples of flame retardants mentioned above include phosphorus-based flame retardants.

[0062] Examples of leveling agents mentioned above include silicone-based leveling agents.

[0063] Examples of anti-blocking agents include acrylic and cellulose esters.

[0064] As the above-mentioned aqueous urethane resin composition (B), an aqueous urethane resin composition with a weight-average molecular weight of 100,000 or more is used. From the viewpoint of obtaining synthetic leather with an adhesive layer having a long pot life, excellent peel strength, and excellent light resistance, a weight-average molecular weight of 100,000 to 700,000 is preferred, and more preferably, it is in the range of 150,000 to 500,000. It should be noted that, in this invention, the weight-average molecular weight represents the value determined by gel permeation chromatography (GPC).

[0065] Examples of the above-mentioned aqueous urethane resin composition (B) include aqueous urethane resin compositions containing urethane resin (b1) and aqueous medium (b2).

[0066] Regarding the aforementioned urethane resin (b1), examples include urethane resins that use polyol compounds (b1-1) and polyisocyanate compounds (b1-2) as essential raw materials.

[0067] Examples of the aforementioned polyol compounds (b1-1) include polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactone polyols, polyacrylic acid polyols, and silicon-modified polyols. These polyol compounds can be used alone or in combination of two or more. It should be noted that these polyol compounds can be derived from petrochemicals or from biomass.

[0068] Examples of the aforementioned polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene polyoxypropylene glycol, and polyoxyethylene polyoxytetramethylene glycol. These polyether polyols can be used alone or in combination of two or more.

[0069] Examples of polyester polyols include polyester polyols obtained by esterification of polycarboxylic acids with polyols.

[0070] Examples of the aforementioned polycarboxylic acids include, for instance, aromatic dicarboxylic acids or their esters such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid; aliphatic dicarboxylic acids or their esters such as succinic acid, glutaric acid, adipic acid, maleic acid, pimelic acid, octanoic acid, azelaic acid, itconic acid, sebacic acid, chlorobridged acid, 1,2,4-butanetricarboxylic acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, dimer acids, and fumaric acid. These polycarboxylic acids or their esters can be used alone or in combination of two or more.

[0071] Examples of the aforementioned polyols include aromatic diols such as benzenediethanol, toluenediethanol, and xylenediethanol, as well as aliphatic polyols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-diethanol, neopentyl glycol, and ethylene glycol. These polyols can be used alone or in combination of two or more.

[0072] In the esterification reaction during the manufacture of the aforementioned polyester polyols, an esterification catalyst is preferably used to promote the esterification reaction. Examples of such esterification catalysts include metals such as titanium, tin, zinc, aluminum, zirconium, magnesium, hafnium, and germanium; and metal compounds such as tetraisopropyl titanium oxide, tetrabutyl titanium oxide, titanium acetylacetonate, dibutyltin oxide, dibutyltin diacetate, dibutyltin dilaurate, tin octoate, 2-ethylhexanetin, zinc acetylacetonate, zirconium tetrachloride, zirconium tetrachloride tetrahydrofuran complex, hafnium tetrachloride, hafnium tetrachloride tetrahydrofuran complex, germanium oxide, and germanium tetraethoxide. These esterification catalysts can be used alone or in combination of two or more.

[0073] Examples of polycarbonate polyols include, for instance, reaction products of carbonates and / or phosgene with compounds having two or more hydroxyl groups.

[0074] Examples of the aforementioned carbonates include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, and propylene carbonate. These carbonates can be used alone or in combination of two or more.

[0075] Examples of compounds having two or more hydroxyl groups include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, 1,5-hexanediol, 3-methyl-1,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,8-nonanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,10-decanediol, 1,12-dodecanediol, 1,4-cyclohexanediol, 1,3-cyclohexanediol, trimethylolpropane, 3-methylpentanediol, neopentanediol, trimethylolethane, and glycerol. These compounds can be used alone or in combination of two or more.

[0076] The number average molecular weight of the aforementioned polyol compound (b1-1) is preferably in the range of 500 to 5,000, from the viewpoint of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength and light resistance.

[0077] The content of the polyol compound (b1-1) is preferably in the range of 50 to 95% by mass in the raw material of the urethane resin (b1), and more preferably in the range of 60 to 90% by mass, from the viewpoint of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength and light resistance.

[0078] Examples of the aforementioned polyisocyanate compounds (b1-2) include, for instance, aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isoflurone diisocyanate, dicyclohexylmethane diisocyanate, phenyl diisocyanate, tetramethylphenyl diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate; alicyclic diisocyanates such as norbornane diisocyanate, isoflurone diisocyanate, hydrogenated phenyl diisocyanate, and hydrogenated diphenylmethane diisocyanate; and aromatic polyisocyanates such as phenylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, phenyl diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, and carbodiimide diphenylmethane polyisocyanate. These polyisocyanate compounds can be used alone or in combination of two or more. Furthermore, among these, from the perspective of obtaining synthetic leather with an adhesive layer that has a long service life, excellent peel strength and light resistance, hexamethylene diisocyanate, isoflurone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate are preferred.

[0079] From the perspective of obtaining synthetic leather with an adhesive layer that has a long service life, excellent peel strength and light resistance, the content of the above-mentioned polyisocyanate compounds (b1-2) in the raw material of the above-mentioned urethane resin (b1) is preferably in the range of 5 to 50% by mass, and more preferably in the range of 10 to 30% by mass.

[0080] As the above-mentioned urethane resin (b1), chain extenders (b1-3) may also be used as needed.

[0081] As the chain extender (b1-3) mentioned above, a chain extender with a molecular weight of less than 500 is preferred. It should be noted that the molecular weight of the chain extender (a3) ​​mentioned above represents a value calculated from the chemical structural formula.

[0082] Examples of chain extenders (a3) ​​include chain extenders with hydroxyl groups and chain extenders with amino groups. These chain extenders can be used alone or in combination of two or more.

[0083] Examples of chain extenders containing hydroxyl groups include aliphatic polyols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylenediol, sucrose, methylenediol, glycerol, and sorbitol; aromatic polyols such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone; and water. These chain extenders can be used alone or in combination of two or more.

[0084] Examples of chain extenders containing amino groups include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperidine, 2-methylpiperidine, 2,5-dimethylpiperidine, isoflurone diamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, hydrazine, diethylenetriamine, and triethylenetetramine. These chain extenders can be used alone or in combination of two or more.

[0085] The amount of the chain extender (b1-3) used, from the perspective of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength and light resistance, is preferably in the range of 0.2 to 20% by mass in the solid component of the urethane resin composition (B), and more preferably in the range of 0.5 to 10% by mass.

[0086] There are no particular limitations on the manufacturing method of the above-mentioned urethane resin (b1), and it can be manufactured by any method. For example, it can be manufactured by reacting all the reactants containing the above-mentioned polyol compound (b1-1) and the above-mentioned polyisocyanate compound (b1-2) with the desired chain extender (b1-3) in a batch, or it can be manufactured by reacting the reactants sequentially. Preferably, these reactions are carried out at a temperature of 50 to 100°C for 3 to 10 hours.

[0087] Regarding the reaction ratio of the polyol compound (b1-1), the polyisocyanate compound (b1-2), and the chain extender (b1-3), from the viewpoint of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength, and light resistance, the molar ratio of the total molar number of hydroxyl groups in the polyol compound (b1-1) and the total molar number of hydroxyl and amino groups in the chain extender (b1-3) to the molar number of isocyanate groups in the polyisocyanate compound (b1-2) [(isocyanate groups) / (hydroxyl and amino groups)] is preferably in the range of 0.90 to 1.30, more preferably in the range of 0.95 to 1.20.

[0088] Alternatively, organic solvents can be used when manufacturing the above-mentioned urethane resin (b1).

[0089] Examples of organic solvents that can be used include ketone compounds such as acetone and methyl ethyl ketone; ether compounds such as tetrahydrofuran and dioxane; acetate compounds such as ethyl acetate and butyl acetate; nitrile compounds such as acetonitrile; and amide compounds such as dimethylformamide and N-methylpyrrolidone. These organic solvents can be used alone or in combination of two or more. It should be noted that the aforementioned organic solvents are preferably removed by distillation or the like when obtaining the aqueous urethane resin composition.

[0090] Regarding the above-mentioned aqueous medium (b2), the same aqueous medium as the aqueous medium exemplified as the above-mentioned aqueous medium (a2) can be used. These aqueous media can be used alone or in combination of two or more.

[0091] The mass ratio of the above-mentioned urethane resin (b1) to the above-mentioned aqueous medium (b2) [(b1) / (b2)] is preferably in the range of 30 / 70 to 80 / 20, and more preferably in the range of 40 / 60 to 70 / 30, from the viewpoint of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength and light resistance.

[0092] There are no particular limitations on the method for manufacturing the above-mentioned aqueous urethane resin composition (B), and it can be manufactured by any method. For example, a method in which the above-mentioned urethane resin (b1) is mixed with the above-mentioned aqueous medium (b2) can be cited.

[0093] As a method for mixing the above-mentioned urethane resin (b1) and the above-mentioned aqueous medium (b2), examples include methods using the following: a reaction vessel equipped with stirring blades; a kneader, a continuous kneader, a conical roller, a single-screw extruder, a twin-screw extruder, a three-screw extruder, a universal mixer, a Plastomill, a Bodeeda-type mixer, etc.; a rotary dispersion mixer, such as a homogenizer, a static mixer, a Filmix, an Ebara Milder, a Clearmix, an ULTRA-TURRAX, a Cavitron, a bio-mixer, etc.; an ultrasonic dispersion device; and a device that does not have a movable part such as an in-tube mixer, but can mix by the flow of the fluid itself.

[0094] The above-mentioned waterborne urethane resin composition (B) may also contain other additives as needed.

[0095] Regarding the other additives mentioned above, the same additives as those exemplified as the other additives mentioned above may be used. The other additives may be used alone or in combination of two or more.

[0096] The mixing ratio of the above-mentioned waterborne urethane resin composition (A) to the above-mentioned waterborne urethane resin composition (B) is preferably in the range of 51 / 49 to 97 / 3, and more preferably in the range of 60 / 40 to 95 / 5, from the viewpoint of obtaining synthetic leather with an adhesive layer having a long service life, excellent peel strength and light resistance.

[0097] The thickness of the aforementioned adhesive layer (ii) can be, for example, in the range of 30 to 60 μm.

[0098] Materials used to form the aforementioned skin layer (iii) (hereinafter sometimes referred to as "skin-forming resin") include, for example, well-known waterborne urethane resins, solvent-based urethane resins, solvent-free urethane resins, waterborne acrylic resins, silicone resins, polypropylene resins, polyester resins, etc. These materials may be used alone or in combination of two or more.

[0099] It should be noted that a surface treatment layer may be further provided on the aforementioned skin layer (iii) to prevent damage, etc. Examples of materials used to form this surface treatment layer include well-known aqueous urethane resins, solvent-based urethane resins, solvent-free urethane resins, aqueous acrylic resins, silicone resins, polypropylene resins, polyester resins, and vinyl chloride resins. These materials may be used individually or in combination of two or more.

[0100] As the aforementioned porous layer, a porous layer formed by a solvent-based urethane resin composition using a well-known wet film-forming method can be used; a porous layer formed by porousizing an aqueous urethane resin composition using a well-known method; or a porous layer formed by foaming a solvent-free urethane resin composition using a well-known method, etc.

[0101] Materials used to form the aforementioned intermediate layer include, for example, well-known aqueous urethane resins, solvent-based urethane resins, solvent-free urethane resins, aqueous acrylic resins, silicone resins, polypropylene resins, polyester resins, and vinyl chloride resins. These materials can be used alone or in combination of two or more.

[0102] There are no particular limitations on the manufacturing method of the above-mentioned synthetic leather, and it can be manufactured by any method. For example, the following methods can be cited: a method (1) in which a skin layer forming resin is coated on a substrate that has undergone a demolding treatment, a drying step is performed to obtain a skin layer (iii), and then the aqueous urethane resin composition of the present invention is coated on the skin layer (iii), dried to form an adhesive layer (ii), and then it is bonded to a base fabric (i); a method (2) in which a skin layer forming resin is coated on a substrate that has undergone a demolding treatment, a drying step is performed to obtain a skin layer (iii), and then the aqueous urethane resin composition of the present invention is coated on the skin layer (iii), bonded to a base fabric (i), and dried to form an adhesive layer (ii).

[0103] Methods for coating the above-mentioned skin-forming resin and the above-mentioned waterborne urethane resin composition include, for example, using an applicator, a roller coater, a sprayer, a T-die coater, a doctor blade coater, a comma-type doctor blade coater, etc.

[0104] After manufacturing the above-mentioned synthetic leather, it can be cured at 30 to 100°C for 1 to 10 days as needed.

[0105] [Example]

[0106] The present invention will now be described in detail through examples and comparative examples. It should be noted that the present invention is not limited to the examples listed below.

[0107] The weight-average molecular weight of the aqueous urethane resin compositions and the number-average molecular weight of the polyol compounds used in the examples and comparative examples are expressed as values ​​determined by gel permeation chromatography (GPC) under the following conditions.

[0108] Measurement apparatus: High-speed GPC device (Tosoh Corporation "HLC-8220GPC")

[0109] Column: Used for connecting the following columns manufactured by Tosoh Corporation in series.

[0110] "TSKgel G5000" (7.8mm I.D. × 30cm) × 1 piece

[0111] "TSKgel G4000" (7.8mm I.D. × 30cm) × 1 piece

[0112] "TSKgel G3000" (7.8mm I.D. × 30cm) × 1 piece

[0113] "TSKgel G2000" (7.8mm I.D. × 30cm) × 1 piece

[0114] Detector: RI (Differential Refractometer)

[0115] Column temperature: 40℃

[0116] Eluent: Tetrahydrofuran (THF)

[0117] Flow rate: 1.0 mL / min

[0118] Injection volume: 100 μL (0.4% by mass tetrahydrofuran solution containing the sample)

[0119] Standard sample: Use the following standard polystyrene to prepare a calibration curve.

[0120] (Standard polystyrene)

[0121] TSKgel Standard Polystyrene A-500 manufactured by Tosoh Corporation

[0122] TSKgel Standard Polystyrene A-1000 manufactured by Tosoh Corporation

[0123] TSKgel Standard Polystyrene A-2500 manufactured by Tosoh Corporation

[0124] TSKgel Standard Polystyrene A-5000 manufactured by Tosoh Corporation

[0125] TSKgel Standard Polystyrene F-1 manufactured by Tosoh Corporation

[0126] TSKgel Standard Polystyrene F-2 manufactured by Tosoh Corporation

[0127] TSKgel Standard Polystyrene F-4 manufactured by Tosoh Corporation

[0128] TSKgel Standard Polystyrene F-10 manufactured by Tosoh Corporation

[0129] TSKgel Standard Polystyrene F-20 manufactured by Tosoh Corporation

[0130] TSKgel Standard Polystyrene F-40 manufactured by Tosoh Corporation

[0131] TSKgel Standard Polystyrene F-80 manufactured by Tosoh Corporation

[0132] TSKgel Standard Polystyrene F-128 manufactured by Tosoh Corporation

[0133] TSKgel Standard Polystyrene F-288 manufactured by Tosoh Corporation

[0134] TSKgel Standard Polystyrene F-550 manufactured by Tosoh Corporation

[0135] (Synthesis Example 1: Preparation of an aqueous urethane resin composition (A1))

[0136] In a four-necked flask equipped with a stirrer, reflux cooling tube, thermometer, and nitrogen blowing tube, under a nitrogen flow, 1,000 parts by mass of polyether polyol (PTMG1000 manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 1,000, hereinafter referred to as "PTMG1000"), 61 parts by mass of methoxy polyethylene glycol (Uniox M1000 manufactured by Nippon Oil Corporation, number average molecular weight: 1,000, hereinafter referred to as "MPEG") and 163 parts by mass of toluene diisocyanate (hereinafter referred to as "TDI") were reacted at 120°C for 3 hours to obtain urethane resin (a1) ([NCO] / [OH] ratio 0.90). Next, the urethane resin (a1) heated to 70°C was mixed with 141 parts by weight of a 35% by weight aqueous solution of sodium alkylnaphthalene sulfonate (manufactured by Kao Corporation, "PELEXNBL") and 309 parts by weight of water. Water was then added further to obtain an aqueous urethane resin composition (A1) containing 50% by weight of urethane resin. The concentration of urea groups in this aqueous urethane resin composition (A1) was 0 mmol / kg.

[0137] (Synthesis Example 2: Preparation of Waterborne Carbamate Resin Composition (B1))

[0138] In a four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube, under a nitrogen stream and in the presence of 0.1 parts by mass of stannous octoate, 1,000 parts by mass of a polyether polyol (PTMG2000 manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 2,000, hereinafter referred to as "PTMG2000"), 24 parts by mass of 2,2-dimethylolpropionic acid (hereinafter referred to as "DMPA"), and 262 parts by mass of dicyclohexylmethane diisocyanate (hereinafter referred to as "HMDI") were reacted at 100°C until the NCO% reached 2.1% by mass, to obtain urethane resin (b1). Next, the urethane resin (b1) heated to 70°C was mixed with 25 parts by mass of triethylamine, 322 parts by mass of a 20% by mass aqueous solution of sodium dodecylbenzenesulfonate (Neogen S-20F manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.), and 670 parts by mass of water. Subsequently, an aqueous dilution of isoflurane diamine (hereinafter referred to as "IPDA") with an amino content equivalent to 95% of the NCO group was immediately added for chain extension, and finally an aqueous urethane resin composition (B1) with a urethane resin content of 50% by mass was obtained.

[0139] (Example 1: Manufacturing of synthetic leather (1))

[0140] A compound solution consisting of 100 parts by weight of an aqueous urethane resin composition for the skin layer (DIC Corporation's "HydranWLS-250"), 10 parts by weight of a water-dispersible black pigment (DIC Corporation's "Dilac HS-9530"), and 1 part by weight of an associative tackifier (DIC Corporation's "Hydran Assistor T10") was coated onto flat release paper (Ajinomoto Corporation's "DN-TP-155T") to achieve a dried film thickness of 30 μm. The mixture was dried at 70°C for 2 minutes and then further dried at 120°C for 2 minutes. Next, 14 parts by mass of a polyisocyanate crosslinking agent (Burnock DNW-5500 manufactured by DIC Co., Ltd.) was added to a mixture of 90 parts by mass of the aqueous urethane resin composition (A1) obtained in Synthetic Example 1 and 10 parts by mass of the aqueous urethane resin composition (B1) obtained in Synthetic Example 2. The mixture was stirred and mixed for 5 minutes. The resulting compound was coated with a solid component film thickness of 50 μm and dried at 90°C for 3 minutes. After being laminated with T / R napped fabric, it was heat-treated at 130°C for 10 minutes, and the release paper was peeled off to obtain synthetic leather (1).

[0141] (Examples 2-5: Manufacturing of synthetic leather (2)-(5))

[0142] Except for changing the proportions of the "waterborne urethane resin composition (A1)" and "waterborne urethane resin composition (B1)" used in Example 1 as shown in Table 1, the same procedure as in Example 1 was followed to obtain synthetic leather (2) to (5).

[0143] (Comparative Example 1: Manufacturing of Synthetic Leather (R1))

[0144] Except for changing the proportions of the "waterborne urethane resin composition (A1)" and "waterborne urethane resin composition (B1)" used in Example 1 as shown in Table 1, the same procedure as in Example 1 was followed to obtain synthetic leather (R1).

[0145] [Method for determining dry peel strength]

[0146] A 2.5 cm wide hot melt adhesive tape (manufactured by SANCHEMICALS Co., Ltd., "BW-2") was placed on the synthetic leather obtained in the examples and comparative examples, and bonded by heating at 150°C for 3 minutes. A sample was cut along the width of the hot melt adhesive tape. A portion of the sample was peeled off, and the substrate and hot melt adhesive tape were clamped together with chucks. The peel strength was measured using an Autograph (manufactured by Shimadzu Corporation, "AG-1"), and evaluated according to the following criteria.

[0147] A: Peel strength is above 3.5 kgf / 25 mm.

[0148] B: Peel strength is above 2.5 kgf / 25 mm and less than 3.5 kgf / 25 mm.

[0149] C: Peel strength less than 2.5 kgf / 25 mm.

[0150] [Method for determining wet (WET) peel strength]

[0151] A 2.5 cm wide hot melt adhesive tape (manufactured by SANCHEMICALS Co., Ltd., "BW-2") was placed on the synthetic leather obtained in the examples and comparative examples, and bonded by heating at 150°C for 3 minutes. A sample was cut along the width of the hot melt adhesive tape. After immersing the sample in water at 23°C for 3 hours, a portion of the sample was peeled off. The substrate and the hot melt adhesive tape were clamped together, and the peel strength was measured using an Autograph (manufactured by Shimadzu Corporation, "AG-1"), and evaluated according to the following criteria.

[0152] A: Peel strength is above 3.5 kgf / 25 mm.

[0153] B: Peel strength is above 2.5 kgf / 25 mm and less than 3.5 kgf / 25 mm.

[0154] C: Peel strength less than 2.5 kgf / 25 mm.

[0155] [Evaluation Methods for the Applicable Period]

[0156] Ten parts by mass of a polyisocyanate crosslinking agent (Burnock DNW-5500, manufactured by DIC Corporation) were added to 100 parts by mass of each of the aqueous urethane resin compositions (A1) and (B1) obtained in the synthetic example. After being placed at 40°C for 4 hours, synthetic leather was prepared in the same manner as in Example 1. A 2.5 cm wide hot melt adhesive tape ("BW-2", manufactured by SANCHEMICALS Corporation) was placed on the synthetic leather and bonded by heating at 150°C for 3 minutes. Next, a sample was cut along the width of the hot melt adhesive tape. A portion of the sample was peeled off, and the substrate and hot melt adhesive tape were clamped together with a clamp. The peel strength was measured by Autograph ("AG-1", manufactured by Shimadzu Corporation) and evaluated according to the following criteria.

[0157] A: Peel strength is above 3.5 kgf / 25 mm.

[0158] B: Peel strength is above 2.5 kgf / 25 mm and less than 3.5 kgf / 25 mm.

[0159] C: Peel strength less than 2.5 kgf / 25 mm.

[0160] [Methods for evaluating lightfastness]

[0161] The synthetic leathers obtained in the examples and comparative examples were subjected to light irradiation for 100 hours using a fading meter "U48AU" (63°C, 50% humidity) manufactured by Suga Test Instruments Co., Ltd. The synthetic leathers were then visually observed and evaluated according to the following criteria.

[0162] A: No change in appearance.

[0163] B: Slight yellowing was observed on the exterior.

[0164] C: Significant yellowing was observed on the exterior.

[0165] Tables 1 and 2 show the formulation amounts and evaluation results of the aqueous urethane resin compositions of the adhesive layer forming materials of the synthetic leathers (1) to (5) and (R1) and (R2) obtained in the above examples and comparative examples.

[0166] [Table 1]

[0167]

[0168] Table 1 lists Examples 1-5 as examples of using the synthetic leather of the present invention. It can be confirmed that the adhesive layer of these synthetic leathers has a long service life, excellent peel strength, and excellent light resistance.

[0169] On the other hand, Comparative Example 1 described in Table 1 is an example of synthetic leather that does not use the aqueous urethane resin composition (B) as the adhesive layer forming material. It can be confirmed that the WET peel strength of the adhesive layer of this synthetic leather is significantly insufficient.

Claims

1. A synthetic leather comprising at least a base fabric (i), an adhesive layer (ii), and an epidermis layer (iii), characterized in that: The adhesive layer (ii) is formed of a mixture containing an aqueous urethane resin composition (A) and an aqueous urethane resin composition (B) other than the aqueous resin composition (A). The aqueous urethane resin composition (A) contains urethane resin (a1), an aqueous medium (a2), and an emulsifier (a3). The urethane resin (a1) requires a polyol compound (a1-1) containing a nonionic polyol and an aromatic polyisocyanate compound (a1-2) as essential raw materials. The concentration of urea bonds in the urethane resin (a1) is below 100 mmol / kg. The waterborne urethane resin composition (B) has a weight-average molecular weight of 100,000 or more.

2. The synthetic leather according to claim 1, wherein, The mixing ratio of the aqueous urethane resin composition (A) to the aqueous urethane resin composition (B) is in the range of 51 / 49 to 97 / 3.

3. The synthetic leather according to claim 1, wherein, The aromatic polyisocyanate compound (a1-2) is toluene diisocyanate.

4. The synthetic leather according to claim 1 or 2, wherein, The emulsifier (a3) ​​comprises anionic emulsifiers.

5. The synthetic leather according to claim 1, wherein, The amount of emulsifier (a3) ​​used is 10 parts by weight or less relative to 100 parts by weight of urethane resin (a1).

6. A method for manufacturing synthetic leather according to any one of claims 1 to 5, wherein, The urethane resin (a1) is obtained by reacting raw materials containing the polyol compound (a1-1) and the aromatic polyisocyanate compound (a1-2) in a solvent-free environment.

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