JP7167676B2 - Urethane resin composition and synthetic leather - Google Patents

Description

The present invention relates to a urethane resin composition and synthetic leather.

A urethane resin is widely used as an adhesive layer for synthetic leather because it has good mechanical strength, elasticity, and adhesiveness. The urethane resin composition used for the adhesive layer of the synthetic leather includes, for example, a crosslinkable urethane resin, a crosslinker, organic fine particles, and N,N-dimethylformamide (hereinafter abbreviated as DMF) as an organic solvent. A containing urethane resin composition has been disclosed (see, for example, Patent Document 1).

However, since the urethane resin composition contains organic fine particles, it has been pointed out that a soft texture cannot be obtained. In addition, DMF, which is used as an organic solvent, is being regulated in Europe and China, and there is a growing need in Japan to reduce its content and replace it with other solvents. Furthermore, with the urethane resin composition, it has been pointed out that the film must be aged for a relatively long period of time after drying the DMF, resulting in poor productivity.

On the other hand, examples of materials that allow release paper to be peeled off without aging (hereinafter abbreviated as "immediate peelability") include cross-linked urethane resins, cross-linking agents, and diazabicycloalkene compound fatty acid A resin composition containing a temperature-sensitive catalyst such as a salt has been disclosed (see, for example, Patent Document 2).

However, such a method has a problem that the usable time after blending the cross-linking agent is extremely short, and it is extremely difficult to actually use it.

In addition, in recent years, assuming use in cold regions, the required level of flexibility at low temperatures (hereinafter abbreviated as "low temperature flexibility") is increasing, and materials that can overcome all these issues are required. It is

Japanese Patent Application Laid-Open No. 2004-346455 JP-A-6-81275

The problem to be solved by the present invention is to provide a urethane resin composition capable of forming a film excellent in low-temperature flexibility, quick release property and texture.

The present invention provides a blocked urethane prepolymer (A) which is a reaction product of a polyol (a1), a polyisocyanate (a2) and a blocking agent (a3), a cross-linking agent (B), an organic solvent (C), and A urethane resin composition containing a foaming agent (D), wherein the organic solvent (C) has a boiling point of less than 230° C., excluding N,N-dimethylformamide, and the crosslinking agent (B) is and an amine compound.

The urethane resin composition of the present invention can form a film that is excellent in low-temperature flexibility, quick releasability, and texture. In addition, the coating is also excellent in adhesiveness.

Therefore, the urethane resin composition of the present invention is suitably used in fields such as synthetic leather, films, adhesives, adhesives, coating agents, vehicle interior materials, moisture-permeable clothing, molded products, polishing pads, shoes, and furniture. It can be used particularly preferably as an adhesive layer for synthetic leather.

The urethane resin composition of the present invention comprises a blocked urethane prepolymer (A) which is a reaction product of a polyol (a1), a polyisocyanate (a2) and a blocking agent (a3), a specific cross-linking agent (B), a specific and an organic solvent (C) and a foaming agent (D).

The blocked urethane prepolymer (A) is an essential component from the viewpoint of solubility in a specific organic solvent (C) described later. In general, DMF has the highest solubility in urethane resins, and its solubility is the most important issue when changing from DMF to a solvent that is not subject to environmental regulations. On the other hand, the blocked urethane prepolymer (A) can exist in the solvent in a state of relatively low molecular weight by using the blocking agent (a3) as a raw material, and when used, it can be dissolved by heat. By applying a block, the block can be removed and reacted with the cross-linking agent (B) to increase the molecular weight, so that the desired properties can be obtained. Thus, by using a blocked urethane prepolymer (A) having a relatively low molecular weight, it is possible to use an organic solvent (C) described later that is less soluble than DMF.

The number average molecular weight of the blocked urethane prepolymer (A) is preferably in the range of 500 to 15,000, more preferably in the range of 800 to 10,000. The number average molecular weight of the blocked urethane prepolymer (A) is the value measured by gel permeation chromatography (GPC).

As the polyol (a1), for example, polyether polyol, polyester polyol, polycaprolactone polyol, polycarbonate polyol, polyacrylic polyol, polybutadiene polyol, hydrogenated polybutadiene polyol and the like can be used. These polyols may be used alone or in combination of two or more. Among these, it is preferable to use a polycarbonate polyol from the viewpoint of obtaining even more excellent low-temperature flexibility, mechanical strength, and adhesiveness.

As the polycarbonate polyol, for example, a reaction product of carbonate ester and/or phosgene and a compound having two or more hydroxyl groups can be used.

As the carbonic acid ester, for example, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate and the like can be used. These compounds may be used alone or in combination of two or more.

Examples of the compound 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, neopentyl glycol, 1,6-hexanediol, 1,5-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1, 8-octanediol, 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-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, trimethylolpropane, trimethylolethane, glycerin, ε-caprolactone, neopentyl glycol, etc. can be used. can. These compounds may be used alone or in combination of two or more.

Among these, 1,3-propane has excellent compatibility with the later-described foaming agent (D) (especially preferred one), and further excellent low-temperature flexibility, mechanical strength, and adhesiveness can be obtained. diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 1,10-decanediol, 1, It is preferable to use one or more compounds selected from the group consisting of 4-cyclohexanedimethanol and 2-methyl-1,8-octanediol, 1,4-butanediol, 1,5-pentanediol, and , 1,6-hexanediol is more preferably one or more selected from the group consisting of 1,6-hexanediol alone, 1,4-butanediol and 1,6-hexanediol in combination, 1,5-pentane One or more selected from the group consisting of a combination of diol and 1,6-hexanediol and a combination of 1,9-nonanediol and 2-methyl-1,8-octanediol is more preferred. These preferred compounds account for preferably 80% by mass or more, more preferably 90% by mass or more, of the total mass of compounds having two or more hydroxyl groups.

When the 1,4-butanediol (C4) and 1,6-hexanediol (C6) are used in combination, the mass ratio [C4/C6] is in the range of 95/5 to 50/50. Preferably, the range of 85/15 to 60/40 is more preferred.

When the 1,5-pentanediol (C5) and 1,6-hexanediol (C6) are used in combination, the mass ratio [C5/C6] is in the range of 80/20 to 20/80. Preferably, the range of 60/40 to 40/60 is more preferred.

When the 1,9-nonanediol (C9) and 2-methyl-1,8-octanediol (C9′) are used in combination, the mass ratio [C9/C9′] is 10/90 to 90/10. is preferably in the range of , more preferably in the range of 10/90 to 70/30.

The number average molecular weight of the polyol (a1) is preferably in the range of 500 to 50,000, and 600 to 10 ,000, more preferably 700 to 5,000, and even more preferably 1,000 to 3,000. The number average molecular weight of the polyol (a1) is the value measured by gel permeation chromatography (GPC).

A chain extender having a number average molecular weight of less than 500 (preferably in the range of 50 to 450) may be used in the polyol (a1), if necessary.

Examples of the chain extender include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, saccharose, methylene Glycol, glycerin, sorbitol, bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, chain extender having a hydroxyl group such as hydroquinone; ethylenediamine , 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4′-dicyclohexylmethanediamine, 3,3′-dimethyl-4 ,4'-dicyclohexylmethanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, hydrazine, diethylenetriamine, triethylenetetramine, adipic acid dihydrazide, etc. can be done. These chain extenders may be used alone or in combination of two or more.

When the chain extender is used, the amount used is preferably in the range of 0.1 to 30 parts by mass with respect to 100 parts by mass of the polyol (a1).

Examples of the polyisocyanate (a2) include aliphatic or aliphatic diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, dimer acid diisocyanate and norbornene diisocyanate. Cyclic polyisocyanates; aromatic polyisocyanates such as phenylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, and carbodiimidated diphenylmethane polyisocyanate can be used. Among these, aromatic polyisocyanate is preferably used, and diphenylmethane diisocyanate and/or toluene diisocyanate are more preferable, from the viewpoint of obtaining even better adhesiveness and texture.

Examples of the blocking agent (a3) include active methylene compounds such as malonate diester, acetylacetone and acetoacetate; ketoxime compounds such as acetoxime, methylethylketoxime and methylisobutylketoxime; methyl alcohol, ethyl alcohol and propyl alcohol. , butyl alcohol, heptyl alcohol, hexyl alcohol, octyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, stearyl alcohol or isomers thereof; methyl glycol, ethyl glycol, ethyl diglycol, ethyl triglycol, butyl Glycol derivatives such as glycol and butyldiglycol; amine compounds such as di-isopropylamine, di-n-butylamine and dicyclohexylamine; phenol, cresol, ethylphenol, n-propylphenol, isopropylphenol, butylphenol, tert-butylphenol, octylphenol , nonylphenol, dodecylphenol, cyclohexylphenol, chlorophenol, bromophenol, resorcinol, catechol, hydroquinone, bisphenol A, bisphenol S, bisphenol F, naphthol; and ε-caprolactone. These compounds may be used alone or in combination of two or more. Among these, the ketoxime compound is preferred because it has a fast blocking reaction, can be deblocked at a temperature higher than the drying temperature of the organic solvent (C), and can form a film with even better low-temperature flexibility and excellent texture. It is preferred to use, more preferably methyl ethyl ketoxime.

As a method for producing the blocked urethane prepolymer (A), for example, the polyol (a1) and the polyisocyanate (a2) are reacted to obtain a urethane prepolymer having isocyanate groups, and then the remaining isocyanate groups are and the blocking agent (a3). Moreover, when producing the blocked urethane prepolymer (A), it may be carried out in the presence of an organic solvent (C) described later.

In the reaction between the polyol (a1) and the polyisocyanate (a2), the molar ratio [NCO/OH] between the isocyanate group and the hydroxyl group is preferably in the range of 1.2 to 5, preferably 1.5 to 3. A range is more preferred.

In the subsequent reaction with the blocking agent (a3), the isocyanate groups of the urethane prepolymer are preferably in the range of 0.8 to 2 mol, more preferably in the range of 0.9 to 1.5 mol. A method of reacting a hydroxyl group in the blocking agent can be mentioned.

As the cross-linking agent (B), 1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopropane, 1,2-diaminobutane, 1,3-diamino butane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, piperazine, N,N'-bis-(2-aminoethyl)piperazine, 1-amino-3-aminomethyl-3 ,5,5-trimethyl-cyclohexane, bis-(4-aminocyclohexyl)methane, bis-(4-amino-3-butylcyclohexyl)methane, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4 - amine compounds such as diaminocyclohexane, 1,3-diaminopropane, norbornenediamine, 4,4'-methylenebis(2-methylcyclohexylamine);

Ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 1,5-pentane diol, neopentyl glycol, 1,6-hexanediol, 1,5-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, 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-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, trimethylolpropane, trimethylolethane, glycerin, ε-caprolactone, neopentyl glycol, polyether polyol, polyester polyol, polycarbonate polyol, polyacrylic polyol, polyurethane polyol, etc. can be used.

As the cross-linking agent (B), it is preferable to use an amine compound, more preferably an amine compound having a cyclohexane structure, from the viewpoint of obtaining even better immediate peelability, low-temperature flexibility, and texture.

The amount of the cross-linking agent (B) is 100 parts by mass of the blocked urethane polypolymer (A) (=solid content) from the viewpoint of obtaining even more excellent immediate peelability, low-temperature flexibility, and texture. On the other hand, it is preferably in the range of 1 to 15 parts by mass, more preferably in the range of 3 to 10 parts by mass.

The cross-linking agent (B) reacts with the isocyanate groups that appear after deblocking of the blocked urethane prepolymer (A) to increase the molecular weight of the urethane resin. It is preferably in the range of 100 to 1,000 mmol/kg, more preferably in the range of 200 to 700 mmol/kg, from the viewpoint of obtaining even better immediate peelability, low-temperature flexibility, and texture.

As the organic solvent (C), it is essential to use one with a boiling point of less than 230° C., excluding DMF. By using such an organic solvent, it becomes an environment-friendly product by removing DMF, and can be dissolved in the blocked urethane polypolymer (A) and the foaming agent (D) described later.

Examples of the organic solvent (C) include methyl ethyl ketone, methyl isobutyl ketone, ethanol, methanol, propanol, 2-propanol, N,N,2-trimethylpropionamide, N,N-dimethylacrylamide, 3-methoxy-N, N-dimethylpropanamide, dimethylsulfoxide, ethyl acetate, butyl acetate, isobutyl acetate, 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate and the like can be used. These organic solvents (C) may be used alone or in combination of two or more.

Among these, the solubility of the blocked urethane prepolymer (A) and the foaming agent (D) can be further improved, and the temperature lower than the deblocking step of the blocked urethane prepolymer (A) Since it can be dried, N,N,2-trimethylpropionamide, N,N-dimethylacrylamide, 3-methoxy-N,N-dimethylpropanamide, dimethylsulfoxide, ethyl acetate, butyl acetate, isobutyl acetate, acetic acid 2 -Ethoxyethyl and, it is preferable to use one or more organic solvents selected from the group consisting of propylene glycol monomethyl ether acetate, N,N,2-trimethylpropionamide, N,N-dimethylacrylamide, and 3- One or more organic solvents selected from the group consisting of methoxy-N,N-dimethylpropanamide are more preferred.

The amount of the organic solvent (C) used is such that the blocked urethane prepolymer (A) and the blowing agent (D) have even better solubility and drying properties. It is preferably in the range of 5 to 70 parts by mass, more preferably in the range of 10 to 50 parts by mass, based on 100 parts by mass of the polymer (A).

The foaming agent (D) is for imparting a foamed structure to the urethane resin film to obtain a good texture.

Examples of the foaming agent (D) include inorganic foaming agents such as sodium carbonate, sodium hydrogen carbonate, calcium carbonate, and magnesium carbonate; azodicarbonamide, N,N-dinitropentamethylenetetramine, p,p'-oxybis Organic blowing agents such as benzenesulfonyl hydrazide, hydrazodicarbonamide, azobisisobutyronitrile, barium azodicarboxylate, and trihydrazinotriazine can be used. These foaming agents may be used alone or in combination of two or more. Among these, the compatibility with the organic solvent (C) (especially preferred organic solvent) and the blocked urethane prepolymer (A) (especially preferred polyol (a1) is used) is excellent, and even more excellent It is preferable to use an organic foaming agent from the viewpoint of obtaining a good texture, and it is selected from the group consisting of azodicarbonamide, N,N'-dinitrosopentamethylenetetramine, and p,p'-oxybisbenzenesulfonyl hydrazide. more preferred are one or more blowing agents.

The amount of the foaming agent (D) to be blended is in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the blocked urethane prepolymer (A) from the viewpoint of obtaining a more excellent texture. is preferred, and the range of 0.5 to 5 parts by mass is more preferred.

The urethane resin composition of the present invention contains the blocked urethane prepolymer (A), the cross-linking agent (B), the organic solvent (C), and the foaming agent (D) as essential components. , may contain other additives.

Examples of other additives include urethanization catalysts, pigments, flame retardants, plasticizers, softeners, stabilizers, waxes, antifoaming agents, dispersants, penetrants, surfactants, fillers, antifungal agents, Antibacterial agents, ultraviolet absorbers, antioxidants, weather stabilizers, fluorescent whitening agents, antioxidants, thickeners, and the like can be used. These additives may be used alone or in combination of two or more.

As described above, the urethane resin composition of the present invention can form a film that is excellent in low-temperature flexibility, quick release property, and texture. In addition, the coating is also excellent in adhesiveness.

Therefore, the urethane resin composition of the present invention is suitably used in fields such as synthetic leather, films, adhesives, adhesives, coating agents, vehicle interior materials, moisture-permeable clothing, molded products, polishing pads, shoes, and furniture. It can be used particularly preferably as an adhesive layer for synthetic leather.

Next, the synthetic leather of the present invention will be explained.

The synthetic leather has at least a base fabric (i), an adhesive layer (ii), and a skin layer (iii), and the adhesive layer (ii) is a layer formed by foaming the urethane resin composition. be.

Examples of the base fabric (i) include 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, Fiber base materials such as non-woven fabrics, woven fabrics, and knitted fabrics made of blended fibers thereof, etc.; non-woven fabrics impregnated with resin such as polyurethane resin; non-woven fabrics further provided with a porous layer; thermoplastic urethane (TPU) etc. can be used.

As the skin layer (iii), for example, those formed from known water-based urethane resins, solvent-based urethane resins, solvent-free urethane resins, water-based acrylic resins, silicone resins, polypropylene resins, polyester resins, etc. can be used. . The resin may be used alone or in combination of two or more.

A surface treatment layer (iv) may be further provided on the skin layer (iii) for scratch prevention and the like. The material for forming the surface treatment layer (iv) can be the same as the material used for forming the skin layer (iii).

Next, a method for manufacturing the synthetic leather will be described.

As a method for producing the synthetic leather, for example, a resin composition for forming a skin layer is applied on a release-treated substrate, and dried to obtain a skin layer (iii). The urethane resin composition is applied onto the skin layer (iii), the organic solvent (C) is dried, the base fabric (i) is attached thereto, and then heat is applied to obtain the urethane resin composition. A method of performing a deblocking treatment of the blocked urethane prepolymer (A) and a foaming treatment of the foaming agent (D).

Examples of the method of applying the resin composition for forming the skin layer and the adhesive layer include methods using an applicator, roll coater, spray coater, T-die coater, knife coater, comma coater, and the like. .

The temperature for drying the organic solvent (C) is, for example, in the range of 80 to 140°C. Further, the temperature for the deblocking treatment and foaming treatment is, for example, in the range of 130 to 200°C.

In the present invention, in particular, when the above-described preferred organic solvent (C) and foaming agent (D) are used, the temperature range for drying the organic solvent (C) is 100 to 130 ° C., deblocking It is preferable to set the temperature range for the treatment to 130°C to 160°C, and the temperature range for the foaming treatment to 160°C to 180°C. can be performed in a preferable state, a synthetic leather having even better low-temperature flexibility, immediate peelability, and texture can be obtained.

The present invention will be described in more detail below using examples.

[Example 1]
Polycarbonate polyols (based on 1,5-pentanediol and 1,6-hexanediol, C5/C6 ( molar ratio) = 50/50, number average molecular weight; 68 parts by mass of N,N,2-trimethylpropionamide (hereinafter abbreviated as “DMIB”) was added with stirring and reacted at 100° C. for 4 hours. Then, the mixture was cooled to 60°C, 16 parts by mass of methyl ethyl ketone oxime (hereinafter abbreviated as "MEKO") was added, and the mixture was allowed to react up to 70°C for 2 hours to form a blocked urethane prepolymer (number average molecular weight: 4,200). got
Next, with respect to 300 parts by mass of the resulting blocked urethane prepolymer, 17 parts by mass of 4,4′-methylenebis(2-methylcyclohexylamine) (hereinafter abbreviated as “amine (1)”), p , p'-oxybisbenzenesulfonyl hydrazide (hereinafter abbreviated as "OBSH") was blended to obtain an adhesive layer formulation liquid.
The concentration of urea groups generated when the blocked urethane prepolymer and amine (1) react is 401 mmol/kg.

[Example 2]
A four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser was charged with 210 parts by mass of PC-1, polycarbonate polyol (made from 1,6-hexanediol, number average molecular weight 2,000, hereinafter abbreviated as “PC-4”) is 53 parts by mass, MDI is 50 parts by mass, 3-methoxy-N,N-dimethylpropanamide (hereinafter abbreviated as “DMPA”) 80 Parts by weight were added while stirring, and reacted at 100° C. for 4 hours. Then, the mixture was cooled to 60°C, 12 parts by mass of MEKO was added, and the reaction was allowed to reach 70°C for 2 hours to obtain a blocked urethane prepolymer (number average molecular weight: 6,400).
Next, 11 parts by mass of amine (1) and 3 parts by mass of OBSH were blended with 300 parts by mass of the blocked urethane prepolymer thus obtained to obtain a liquid composition for an adhesive layer.
The concentration of urea groups generated when the blocked urethane prepolymer and amine (1) react is 258 mmol/kg.

[Example 3]
Polycarbonate polyols (based on 1,4-butanediol and 1,6-hexanediol, C4/C6 ( 210 parts by mass of MDI, 45 parts by mass of MDI, and ethyl acetate (hereinafter abbreviated as "ETAc"). ) 64 parts by mass were added with stirring, and reacted at 100° C. for 4 hours. Then, the mixture was cooled to 60°C, 15 parts by mass of MEKO was added, and the reaction was allowed to reach 70°C for 2 hours to obtain a blocked urethane prepolymer (number average molecular weight: 4,400).
Next, 16.5 parts by mass of amine (1) and 2.3 parts by mass of OBSH were blended with 300 parts by mass of the blocked urethane prepolymer thus obtained to obtain a liquid composition for an adhesive layer.
The concentration of urea groups generated when the blocked urethane prepolymer and amine (1) react is 385 mmol/kg.

[Example 4]
Polycarbonate polyols (made from 1,9-nonanediol and 2-methyl-1,8-octanediol, C9/C9' (molar ratio) = 65/35, number average molecular weight; 2,000, hereinafter abbreviated as "PC-3") 240 parts by mass, toluene diisocyanate (hereinafter abbreviated as "TDI") 31.5 parts by mass and 68 parts by mass of propyl acetate (hereinafter abbreviated as “PrAc”) were added while stirring, and reacted at 100° C. for 4 hours. Then, the mixture was cooled to 60°C, 11 parts by mass of MEKO was added, and the reaction was allowed to reach 70°C for 2 hours to obtain a blocked urethane prepolymer (number average molecular weight: 6,100).
Next, 11.5 parts by mass of amine (1) and 3.3 parts by mass of OBSH were blended with 300 parts by mass of the blocked urethane prepolymer thus obtained to obtain a liquid composition for an adhesive layer.
The concentration of urea groups generated when the blocked urethane prepolymer and amine (1) react is 272 mmol/kg.

[Example 5]
In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser, 210 parts by mass of PC-2, polycarbonate polyol (made from 1,6-hexanediol, number average molecular weight 2,000, hereinafter abbreviated as “PC-4”), 37 parts by mass of TDI, and 75 parts by mass of propylene glycol monomethyl ether acetate (hereinafter abbreviated as “PGMAc”) while stirring. and reacted at 100° C. for 4 hours. Then, the mixture was cooled to 60°C, 14 parts by mass of MEKO was added, and the reaction was allowed to reach 70°C for 2 hours to obtain a blocked urethane prepolymer (number average molecular weight: 5,200).
Next, 14 parts by weight of amine (1) and 4 parts by weight of azodicarbonamide (hereinafter abbreviated as "ADCA") are blended with 300 parts by weight of the resulting blocked urethane prepolymer, for the adhesive layer. A mixed solution was obtained.
The concentration of urea groups generated when the blocked urethane prepolymer and amine (1) react is 323 mmol/kg.

[Example 6]
220 parts by mass of PC-1, 33 parts by mass of TDI, and butyl acetate (hereinafter abbreviated as "BuAc") are placed in a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser. ) was added while stirring, and the mixture was reacted at 100° C. for 4 hours. Then, the mixture was cooled to 60°C, 14.5 parts by mass of MEKO was added, and the reaction was allowed to reach 70°C for 2 hours to obtain a blocked urethane prepolymer (weight average molecular weight: 4,500).
Next, 16 parts by mass of amine (1) and 1.5 parts of N,N'-dinitrosopentamethylenetetramine (hereinafter abbreviated as "DPT") are added to 300 parts by mass of the resulting blocked urethane prepolymer. Parts by mass were blended to obtain a blended liquid for an adhesive layer.
The concentration of urea groups generated when the blocked urethane prepolymer and amine (1) react is 375 mmol/kg.

[Comparative Example 1]
A four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser was charged with a urethane prepolymer having hydroxyl groups at its ends ("Crisbon TA-205FT" manufactured by DIC Corporation, hereinafter "hydroxyl-terminated Pr" abbreviated as.) 100 parts by mass, polyisocyanate cross-linking agent (DIC Corporation "Barnock DN-950", hereinafter abbreviated as "NCO (1)") 12 parts by mass, catalyst (DIC Corporation "Crisbon 2 parts by mass of Accel T-81E"), 60 parts by mass of DMIB, and 4.5 parts by mass of OBSH were blended with a homomixer to obtain a blended liquid. After applying the blended liquid to a release paper with a skin layer, it was adhered in a state where the solvent was dried with a drier. When the immediate peelability test was conducted after the adhesion, the adhesive layer was peeled off, so the immediate peelability could not be measured, and subsequent evaluation could not be performed, and the rating was given as "-".

[Measurement method of number average molecular weight, etc.]
The number average molecular weight of the polyol and the number average molecular weight of the blocked urethane prepolymer are measured by gel permeation column chromatography (GPC) under the following conditions.

Measuring device: high-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series and used.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 Book "TSKgel G2000" (7.8 mm ID x 30 cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40°C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)
Standard sample: A calibration curve was created using the following standard polystyrene.

(standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

[Preparation of liquid mixture for skin layer]
100 parts by mass of a solvent-based urethane resin ("Crisbon NY-331" manufactured by DIC Corporation) and 20 parts by mass of a black pigment ("DILAC L-1770S" manufactured by DIC Corporation) are stirred with a mechanical mixer at 2,000 rpm for 2 minutes, Next, a vacuum deaerator was used to defoam the mixture to obtain a skin layer formulation.

[Evaluation method for immediate peelability]
On release paper (“EK-100D” manufactured by Lintec Co., Ltd.), the mixture for the skin layer was applied with a knife coater so that the film thickness after drying was 150 μm, and then dried at 70 ° C. using a hot air dryer. A skin layer was formed by drying at 120° C. for 2 hours and then at 120° C. for 2 minutes. Next, the compounded liquid for adhesive layer (immediately after compounding the cross-linking agent and foaming agent) obtained in Examples and Comparative Examples was applied onto the skin layer so that the film thickness after drying was 150 μm, It was dried at 120°C for 2 minutes. Next, this was laminated with a non-woven fabric and heated at 150° C. for 2 minutes and 170° C. for 2 minutes to obtain a synthetic leather having an adhesive layer in which a foaming agent was foamed.
Five minutes later, the release paper was peeled off, a 5-yen coin was placed on the surface layer of the synthetic leather obtained, a weight of 1 kg was placed thereon, and the synthetic leather was left for 24 hours. After that, the degree of hardening was evaluated as follows from the five-yen coin mark left on the synthetic leather.
“◯”: The outer edge and/or the inner edge of the 5-yen coin are confirmed, but the inner pattern is not confirmed.
"X": The outer edge, inner edge, and inner pattern of the 5-yen coin are confirmed.

[Evaluation of low-temperature flexibility]
The synthetic leather obtained in the above [Evaluation method for immediate release] was subjected to a flexometer (-10 ° C., 100 times / minute) with a flexometer (manufactured by Yasuda Seiki Seisakusho Co., Ltd. "Flexometer with low temperature chamber"). The number of times until cracks occurred on the surface of the synthetic leather was measured and evaluated as follows.
“○”: 50,000 times or more “△”: 10,000 times or more and less than 50,000 times “×”: Less than 10,000 times

[Evaluation method of texture]
The synthetic leather obtained in the above [Evaluation method for immediate peelability] was touched with a finger and evaluated as follows.
"◯": Soft and voluminous.
"Δ": Slightly hard, but inferior in voluminousness.
"X": Hard or inferior in voluminousness.

In Examples 1 to 6, which are the urethane resin compositions of the present invention, urethane resin compositions capable of forming films with excellent low-temperature flexibility, quick release properties, and excellent texture were obtained.

On the other hand, in Comparative Example 1, instead of the blocked urethane prepolymer (A), a high-molecular-weight polyurethane containing no blocking agent (a3) was used. .

Claims (5)

A blocked urethane prepolymer (A) which is a reaction product of a polyol (a1), a polyisocyanate (a2) and a blocking agent (a3), a cross-linking agent (B), an organic solvent (C), and a foaming agent (D ) is a urethane resin composition containing
The polyol (a1) is a polycarbonate polyol,
The organic solvent (C) has a boiling point of less than 230° C., excluding N,N-dimethylformamide,
The cross-linking agent (B) is an amine compound,
The foaming agent (D) is one or more selected from the group consisting of azodicarbonamide, N,N'-dinitrosopentamethylenetetramine, and p,p'-oxybisbenzenesulfonyl hydrazide. A urethane resin composition. 2. The urethane resin composition according to claim 1 , wherein said polyisocyanate (a2) is an aromatic polyisocyanate. 3. The urethane resin composition according to claim 2 , wherein said aromatic polyisocyanate is diphenylmethane diisocyanate and/or toluene diisocyanate. The organic solvent (C) is N,N,2-trimethylpropionamide, N,N-dimethylacrylamide, 3-methoxy-N,N-dimethylpropanamide, dimethylsulfoxide, ethyl acetate, butyl acetate, isobutyl acetate, acetic acid 4. The urethane resin composition according to any one of claims 1 to 3 , which is one or more organic solvents selected from the group consisting of 2-ethoxyethyl and propylene glycol monomethyl ether acetate. A synthetic leather having at least a base fabric (i), an adhesive layer (ii), and a skin layer (iii), wherein the adhesive layer (ii) is the urethane according to any one of claims 1 to 4 . Synthetic leather characterized by being a foam of a resin composition.