Aqueous urethane resin composition and synthetic leather

Abstract

The present invention provides an aqueous urethane resin composition which contains a urethane resin (A) and an aqueous medium (B), said composition being characterized in that: the urethane resin (A) contains a polyol compound (a1) that contains a polycarbonate polyol (a1-1) and a polyisocyanate compound (a2) as essential reaction starting materials; the polycarbonate polyol (a1-1) contains a polycarbonate polyol that contains a diol compound having 2-4 carbon atoms as an essential starting material; and the amount of the diol compound having 2-4 carbon atoms used therefor is in the range of 10-90 mol% in the starting material diol compound of the polycarbonate polyol (a1-1). This aqueous urethane resin composition exhibits excellent chemical resistance and low-temperature bendability.

Description

Water-based urethane resin composition and synthetic leather

[0001] The present invention relates to an aqueous urethane resin composition and synthetic leather.

[0002] Urethane resin compositions have excellent mechanical strength, elasticity, adhesiveness, etc., and also exhibit a good texture, and therefore are widely used in adhesive layers and surface layers of synthetic leathers (including artificial leathers).

[0003] High durability is required of the urethane resin composition, particularly when it is used for components that will be used for a long period of time, such as synthetic leather for vehicle interior materials. Evaluation items for this durability are wide-ranging, and include heat resistance, moist heat resistance, light resistance, chemical resistance, and abrasion resistance (see, for example, Patent Document 1). In particular, in recent years, chemical resistance to oleic acid has been required for synthetic leather components that frequently come into contact with the human body, and flexibility at low temperatures is also required in anticipation of use in cold regions.

[0004] As a urethane resin composition for synthetic leather having the above-mentioned high durability, there is known a polyurethane resin composition for synthetic leather containing a polyisocyanate, a polyol, and a chain extender, wherein the polyol contains a polyester polyol in which sebacic acid is used in an amount of 60 to 100 mol % among the dibasic acid components (see, for example, Patent Document 2). However, this composition does not satisfy the increasingly high demands for chemical resistance and low-temperature flexibility, and is not sufficient for meeting current market demands.

[0005] Therefore, there has been a demand for a material that has excellent chemical resistance and low-temperature flexibility.

[0006] JP 2016-222921 A JP 2022-81047 A

[0007] The problem to be solved by the present invention is to provide an aqueous urethane resin composition and synthetic leather having excellent chemical resistance and low-temperature flexibility.

[0008] The present inventors have found that the above problems can be solved by using a polycarbonate polyol containing a specific diol compound having 2 to 4 carbon atoms as an essential raw material as a polyol compound that is a raw material for a urethane resin, and have completed the present invention.

[0009] Specifically, the present invention relates to an aqueous urethane resin composition containing a urethane resin (A) and an aqueous medium (B), wherein the urethane resin (A) comprises, as essential reaction raw materials, a polyol compound (a1) containing a polycarbonate polyol (a1-1) and a polyisocyanate compound (a2), the polycarbonate polyol (a1-1) comprising a polycarbonate polyol whose essential raw material is a diol compound having 2 to 4 carbon atoms, and the amount of the diol compound having 2 to 4 carbon atoms used is in the range of 10 to 90 mol % of the raw material diol compound for the polycarbonate polyol (a1-1). The aqueous urethane resin composition and synthetic leather are also provided.

[0010] The aqueous urethane resin composition of the present invention has excellent chemical resistance and low-temperature flexibility, and therefore can be suitably used as a material for synthetic leather and artificial leather.

[0011] The aqueous urethane resin composition of the present invention is characterized by containing a urethane resin (A) and an aqueous medium (B).

[0012] The urethane resin (A) contains a polyol compound (a1) and a polyisocyanate compound (a2) as essential raw materials.

[0013] As the polyol compound (a1), one containing a polycarbonate polyol (a1-1) is used.

[0014] As the polycarbonate polyol (a1-1), a polycarbonate polyol containing a diol compound having 2 to 4 carbon atoms as an essential raw material is used.

[0015] The amount of the diol compound having 2 to 4 carbon atoms used is in the range of 10 to 90 mol % in the raw material diol compound of the polycarbonate polyol (a1-1), and since an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained, the range of 15 to 90 mol % is preferable, and the range of 25 to 90 mol % is more preferable.

[0016] The diol compound having 2 to 4 carbon atoms can reduce the environmental load, so a biomass-derived (hereinafter, sometimes referred to as "bio-based") diol compound can also be used. In the present invention, "bio-based" means that it is produced from plant materials such as sugarcane, corn, and castor oil. In the present invention, a polycarbonate polyol obtained using the bio-based material may be referred to as a "bio-based polycarbonate polyol."

[0017] Examples of the polycarbonate polyol (a1-1) include polycarbonate polyol (a1-1-1) obtained by reacting a carbonate ester and / or phosgene with a diol compound having 2 to 4 carbon atoms, copolymer polycarbonate polyol (a1-1-2) obtained by reacting a carbonate ester and / or phosgene with a diol compound having 2 to 4 carbon atoms and a diol compound having 5 or more carbon atoms, and polycarbonate polyol (a1-1-3) using a carbonate ester and / or phosgene and a diol compound having 5 or more carbon atoms as essential raw materials. These polycarbonate polyols can be used alone or in combination of two or more.

[0018] Examples of the carbonate ester include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate, etc. These carbonate esters can be used alone or in combination of two or more.

[0019] Examples of the diol compound having 2 to 4 carbon atoms include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, etc. These diol compounds having 2 to 4 carbon atoms can be used alone or in combination of two or more.

[0020] Examples of the diol compound having 5 or more carbon atoms include aliphatic diol compounds such as 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, 1,10-decanediol, 2-ethyl-2-butyl-1,3-propanediol, and 1,12-dodecanediol; and alicyclic diol compounds such as 1,4-cyclohexanedimethanol and 1,3-cyclohexanedimethanol. These diol compounds having 5 or more carbon atoms can be used alone or in combination of two or more.

[0021] As the polycarbonate polyol (a1-1), it is preferable to use in combination at least two kinds selected from the group consisting of the polycarbonate polyol (a1-1-1), the copolymer polycarbonate polyol (a1-1-2), and the polycarbonate polyol (a1-1-3), since an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained.

[0022] The number average molecular weight of the polycarbonate polyol (a1-1) is preferably in the range of 500 to 100,000, and more preferably in the range of 700 to 4000, since an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained. In the present invention, the number average molecular weight of the polycarbonate polyol indicates a value measured by gel permeation chromatography (GPC).

[0023] The amount of the polyol compound (a1) used in the raw materials for the urethane resin (A) is preferably in the range of 30 to 90 mass %, more preferably in the range of 40 to 80 mass %, because an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained.

[0024] As the polyol compound (a1), polyol compounds other than the polycarbonate polyol (a1-1-1), the copolymeric polycarbonate polyol (a1-1-2), and the polycarbonate polyol (a1-1-3) (hereinafter abbreviated as "other polyol compounds") can also be used, if necessary.

[0025] Examples of the other polyol compounds include polyols having a hydrophilic group, polyester polyols, polyether polyols, polybutadiene polyols, etc. These polyol compounds can be used alone or in combination of two or more.

[0026] Examples of the polyol having a hydrophilic group include polyols having a carboxyl group such as 2,2'-dimethylolpropionic acid, 2,2'-dimethylolbutanoic acid, 2,2'-dimethylolbutyric acid, and 2,2'-dimethylolvaleric acid, and polyols having a sulfonic acid group such as 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, and 5[4-sulfophenoxy]isophthalic acid. These polyols having a hydrophilic group can be used alone or in combination of two or more.

[0027] Examples of the polyester polyol include those obtained by esterifying a polycarboxylic acid with a polyhydric alcohol.

[0028] Examples of the polycarboxylic acid include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid, and esters thereof, and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, maleic acid, pimelic acid, suberic acid, azelaic acid, itaconic acid, sebacic acid, chlorendic acid, 1,2,4-butanetricarboxylic acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, dimer acid, and fumaric acid, and esters thereof. These polycarboxylic acids and esters thereof can be used alone or in combination of two or more.

[0029] Examples of the polyhydric alcohol include aromatic diols such as benzenedimethanol, toluenedimethanol, and xylene dimethanol, and aliphatic polyols such as ethylene glycol, propylene glycol, 1,3-propylene diol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, and neopentyl glycol ethylene glycol. These polyhydric alcohols can be used alone or in combination of two or more.

[0030] In the esterification reaction for producing the polyester polyol, it is preferable to use an esterification catalyst for the purpose of accelerating the esterification reaction. Examples of the esterification catalyst include metals such as titanium, tin, zinc, aluminum, zirconium, magnesium, hafnium, and germanium; and metal compounds such as titanium tetraisopropoxide, titanium tetrabutoxide, titanium oxyacetylacetonate, 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 tetraethoxygermanium. These esterification catalysts can be used alone or in combination of two or more.

[0031] Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, etc. These polyether polyols can be used alone or in combination of two or more.

[0032] The number average molecular weight of the other polyol compounds is preferably in the range of 200 to 100,000, more preferably in the range of 500 to 10,000, since an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained.

[0033] The content of the other polyol compounds in the polyol compound (a1) is preferably in the range of 0 to 90% by mass.

[0034] Examples of the polyisocyanate compound (a2) include aromatic polyisocyanates such as phenylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, and carbodiimidized diphenylmethane polyisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate; and alicyclic diisocyanates such as norbornane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate. These polyisocyanates can be used alone or in combination of two or more. Among these, hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate are preferred because they provide an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility.

[0035] The amount of the polyisocyanate compound (a2) used is preferably in the range of 10 to 40 mass%, more preferably in the range of 12 to 37 mass%, and even more preferably in the range of 15 to 35 mass%, of the total mass of the raw materials for the urethane resin (A), since an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained.

[0036] In addition to the polyol compound (a1) and the polyisocyanate compound (a2), a chain extender (a3) ​​may also be used as a raw material for the urethane resin (A), if necessary.

[0037] Examples of the chain extender (a3) ​​include chain extenders having a hydroxyl group, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, trimethylolpropane, and glycerin; and chain extenders having an amino group, such as 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, and triethylenetetramine. These chain extenders can be used alone or in combination of two or more. Among these, a chain extender having a hydroxyl group is preferred, and ethylene glycol, diethylene glycol, 1,3-propanediol, and 1,4-butanediol are more preferred, as they provide an aqueous urethane resin composition with excellent chemical resistance and low-temperature flexibility. Furthermore, bio-based ethylene glycol, bio-based 1,3-propanediol, bio-based 1,4-butanediol, etc. can also be used, as they reduce the environmental impact.

[0038] The amount of the chain extender (a3) ​​used is preferably in the range of 0.1 to 50 mass %, more preferably 1 to 30 mass %, of the total mass of the raw materials for the urethane resin (A), since an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained.

[0039] The method for producing the urethane resin (A) is not particularly limited, and examples thereof include a method (1) in which raw materials including the polyol compound (a1), the polyisocyanate compound (a2), and, if necessary, a chain extender (a3) ​​are charged all at once and reacted in an organic solvent.

[0040] Examples of the organic solvent include ketone solvents such as methyl ethyl ketone, acetone, dimethylformamide, and methyl isobutyl ketone; cyclic ether solvents such as tetrahydrofuran and dioxolane; ester solvents such as methyl acetate, ethyl acetate, and butyl acetate; aromatic solvents such as toluene, xylene, and solvent naphtha; alicyclic solvents such as cyclohexane and methylcyclohexane; alcohol solvents such as carbitol, cellosolve, methanol, isopropanol, butanol, and propylene glycol monomethyl ether; glycol ether solvents such as alkylene glycol monoalkyl ethers, dialkylene glycol monoalkyl ethers, and dialkylene glycol monoalkyl ether acetates; methoxypropanol, cyclohexanone, methyl cellosolve, diethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate. These organic solvents can be used alone or in combination of two or more.

[0041] The reaction temperature in the method (1) is preferably in the range of 30 to 100°C, more preferably in the range of 70 to 90°C.

[0042] The reaction time in the method (1) is preferably in the range of 3 to 10 hours, more preferably in the range of 4 to 10 hours.

[0043] In the reaction of the polyol compound (a1) with the polyisocyanate compound (a2) in the method (1), an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained, and therefore the mass ratio [(a1) / (a2)] is preferably in the range of 85 / 15 to 65 / 35.

[0044] The number average molecular weight of the urethane resin (A) is preferably in the range of 5,000 to 1,000,000, and more preferably in the range of 10,000 to 500,000, since an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained.

[0045] The content of the urethane resin (A) in the urethane resin composition is preferably in the range of 10 to 90 mass%, more preferably in the range of 15 to 80 mass%, because an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained.

[0046] Examples of the aqueous medium (B) include ion-exchanged water, distilled water, etc. These aqueous media can be used alone or in combination of two or more.

[0047] The mass ratio [(A) / (B)] of the urethane resin (A) to the aqueous medium (B) is preferably in the range of 20 / 80 to 80 / 20, more preferably in the range of 30 / 70 to 70 / 30, since an aqueous urethane resin composition having excellent chemical resistance and low-temperature flexibility can be obtained.

[0048] The method for producing the aqueous urethane resin composition (A) is not particularly limited, and any method may be used, such as a method of mixing the urethane resin (a1) and the aqueous medium (a2).

[0049] Examples of methods for mixing the urethane resin (a1) and the aqueous medium (a2) include methods using a reaction vessel equipped with a stirring blade; a kneader such as a kneader, a continuous kneader, a taper roll, a single-screw extruder, a twin-screw extruder, a triple-screw extruder, a universal mixer, a Plastomill, or a Bodeta-type kneader; a rotary dispersion mixer such as a homomixer, a static mixer, FILMICS, an Ebara Milder, a Clearmix, an Ultra-Turrax, a Cavitron, or a Biomixer; an ultrasonic dispersion device; or a device such as an in-line mixer that has no moving parts and can mix by the flow of the fluid itself.

[0050] The aqueous urethane resin composition (A) may contain other additives as needed.

[0051] Furthermore, the urethane resin composition of the present invention may contain, as necessary, for example, pigments, flame retardants, plasticizers, softeners, stabilizers, waxes, antifoaming agents, dispersants, penetrating agents, surfactants, fillers, antifungal agents, antibacterial agents, ultraviolet absorbers, antioxidants, weathering stabilizers, fluorescent brighteners, antiaging agents, thickeners, etc. These may be used alone or in combination of two or more.

[0052] The synthetic leather of the present invention has a layer formed from the urethane resin composition.

[0053] The synthetic leather of the present invention has at least a base fabric (i), an adhesive layer (ii), and a surface layer (iii), and examples thereof include the following synthetic leathers (1) to (4).

[0054] Synthetic leather (1): Base fabric (i), adhesive layer (ii), skin layer (iii) Synthetic leather (2): Base fabric (i), adhesive layer (ii), intermediate layer, skin layer (iii) Synthetic leather (3): Base fabric (i), porous layer, adhesive layer (ii), skin layer (iii) Synthetic leather (4): base fabric (i), porous layer, adhesive layer (ii), intermediate layer, skin layer (iii)

[0055] Examples of the base fabric (i) include nonwoven fabrics, woven fabrics, knitted fabrics, and the like made from polyester fibers, polyethylene fibers, nylon fibers, acrylic fibers, polyurethane fibers, acetate fibers, rayon fibers, polylactic acid fibers, cotton, hemp, silk, wool, glass fibers, carbon fibers, and blends thereof.

[0056] As the adhesive layer (ii), a known material for forming an adhesive layer (ii) (hereinafter, sometimes referred to as "resin for forming adhesive layer") is used.

[0057] Examples of the resin for forming the adhesive layer include known aqueous urethane resins, solvent-based urethane resins, solventless urethane resins, aqueous acrylic resins, silicone resins, polypropylene resins, polyester resins, etc. These materials can be used alone or in combination of two or more.

[0058] The thickness of the adhesive layer (ii) is, for example, in the range of 30 to 60 μm.

[0059] The surface layer (iii) is formed from the aqueous urethane resin composition of the present invention.

[0060] A surface treatment layer may be further provided on the surface layer (iii) to prevent scratches, etc. Examples of materials for forming the surface treatment layer include known aqueous urethane resins, solvent-based urethane resins, solventless urethane resins, aqueous acrylic resins, silicone resins, polypropylene resins, polyester resins, and vinyl chloride resins. These materials may be used alone or in combination of two or more.

[0061] The porous layer may be formed from a solvent-based urethane resin composition by a known wet film-forming method; a water-based urethane resin composition that has been made porous by a known method; or a solventless urethane resin composition that has been foamed by a known method.

[0062] Examples of materials for forming the intermediate layer include known aqueous urethane resins, solvent-based urethane resins, solventless urethane resins, aqueous acrylic resins, silicone resins, polypropylene resins, polyester resins, vinyl chloride resins, etc. These materials can be used alone or in combination of two or more.

[0063] The synthetic leather may be produced by any method without any particular limitation. Examples thereof include a method (1) in which a resin for forming a surface layer is applied to a release-treated substrate, followed by drying and processing to obtain a surface layer (iii), and then the aqueous urethane resin composition of the present invention is applied to the surface layer (iii) and dried to form an adhesive layer (ii), which is then laminated to a base fabric (i), and a method (2) in which a resin for forming a surface layer is applied to a release-treated substrate, followed by drying and processing to obtain a surface layer (iii), and then the aqueous urethane resin composition of the present invention is applied to the surface layer (iii), which is then laminated to a base fabric (i), followed by drying to form an adhesive layer (ii).

[0064] After the synthetic leather is produced, it may be aged, for example, at 30 to 100° C. for 1 to 10 days, if necessary.

[0065] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the examples given below.

[0066] The number average molecular weights of the polyol compounds and the like used in the examples and comparative examples are values ​​measured by gel permeation chromatography (GPC) under the following conditions.

[0067] Measurement apparatus: High-speed GPC apparatus ("HLC-8220GPC" manufactured by Tosoh Corporation) Column: The following columns manufactured by Tosoh Corporation were used, connected in series: "TSKgel G5000" (7.8 mm I.D. x 30 cm) x 1, "TSKgel G4000" (7.8 mm I.D. x 30 cm) x 1, "TSKgel G3000" (7.8 mm I.D. x 30 cm) x 1, "TSKgel G2000" (7.8 mm I.D. 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 prepared using the following standard polystyrene.

[0068] (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

[0069] Synthesis Example 1: Synthesis of polycarbonate polyol (PC-1) A four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser was charged with 450 parts by mass of 1,3-propanediol (biomass-derived) and 1,267 parts by mass of diphenyl carbonate (equimolar relative to the 1,3-propanediol), and 0.01% by weight of tetraisopropyl titanate was added as a catalyst. The mixture was reacted at 200°C for 5 hours, and then under reduced pressure for 10 hours to obtain polycarbonate polyol (PC-1). The hydroxyl value of this polycarbonate polyol (PC-1) was 56.0 mgKOH / g.

[0070] (Synthesis Example 2: Synthesis of polycarbonate polyol (PC-2)) Polycarbonate polyol (PC-2) was obtained in the same manner as in Example 1, except that 1,032 parts by mass of 1,10-decanediol (biomass-derived) was used instead of 450 parts by mass of 1,3-propanediol used in Synthesis Example 1. The hydroxyl value of this polycarbonate polyol (PC-2) was 55.3 mgKOH / g.

[0071] (Synthesis Example 3: Synthesis of polycarbonate polyol (PC-3)) Polycarbonate polyol (PC-3) was obtained in the same manner as in Example 1, except that "373 parts by mass of 1,4-butanediol and 309 parts by mass of 1,10-decanediol (biomass-derived)" were used instead of "450 parts by mass of 1,3-propanediol" used in Synthesis Example 1. The hydroxyl value of this polycarbonate polyol (PC-3) was 37.6 mgKOH / g.

[0072] (Synthesis Example 4: Synthesis of polycarbonate polyol (PC-4)) Polycarbonate polyol (PC-4) was obtained in the same manner as in Example 1, except that "266 parts by mass of 1,4-butanediol and 308 parts by mass of 1,5-pentanediol" were used instead of "450 parts by mass of 1,3-propanediol" used in Synthesis Example 1. The hydroxyl value of this polycarbonate polyol (PC-4) was 55.7 mgKOH / g.

[0073] (Synthesis Example 5: Synthesis of polycarbonate polyol (PC-5)) Polycarbonate polyol (PC-5) was obtained in the same manner as in Example 1, except that "266 parts by mass of 1,4-butanediol (biomass-derived) and 349 parts by mass of 1,6-hexanediol" were used instead of "450 parts by mass of 1,3-propanediol" used in Synthesis Example 1. The hydroxyl value of this polycarbonate polyol (PC-5) was 56.0 mgKOH / g.

[0074] (Synthesis Example 6: Synthesis of polycarbonate polyol (PC-6)) Polycarbonate polyol (PC-6) was obtained in the same manner as in Example 1, except that 700 parts by mass of 1,6-hexanediol was used instead of 450 parts by mass of 1,3-propanediol used in Synthesis Example 1. The hydroxyl value of this polycarbonate polyol (PC-6) was 55.0 mgKOH / g.

[0075] Example 1 Preparation of Aqueous Urethane Resin Composition (1) In a four-neck flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 150 parts by mass of the polycarbonate polyol (PC-1) obtained in Synthesis Example 1, 850 parts by mass of the polycarbonate polyol (PC-2) obtained in Synthesis Example 2, 38 parts by mass of polyethylene glycol ("PEG600" manufactured by NOF Corporation, number average molecular weight: 600, hereinafter abbreviated as "PEG"), and 262 parts by mass of 4,4'-dicyclohexylmethane diisocyanate (H12MDI) were reacted at 100°C under a nitrogen stream in the presence of 0.1 parts by mass of stannous octoate to obtain a urethane prepolymer.

[0076] Next, the urethane prepolymer heated to 70°C, 65 parts by mass of a 20% aqueous solution of emulsifier sodium dodecylbenzenesulfonate ("Neogen S-20F" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and 948 parts by mass of water were stirred and mixed in a homomixer to obtain an emulsion. Immediately thereafter, a water-diluted solution of isophoronediamine (IPDA) having an amino group content equivalent to the molar amount of NCO groups was added to carry out chain extension, finally obtaining an aqueous urethane resin composition (1) with a solids content of 58% by mass.

[0077] Example 2 Preparation of Aqueous Urethane Resin Composition (2) In a four-neck flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 400 parts by mass of polycarbonate polyol (PC-1), 600 parts by mass of polycarbonate polyol (PC-3) obtained in Synthesis Example 3, 35 parts by mass of PEG, and 210 parts by mass of H12MDI were reacted at 100°C in the presence of 0.1 part by mass of stannous octoate under a nitrogen stream until the NCO% reached 2.3%, to obtain a urethane prepolymer.

[0078] Next, the urethane prepolymer heated to 70°C, 62 parts by mass of a polypropylene-polyethylene copolymer ("Pluronic (registered trademark) L-64" manufactured by ADEKA Corporation) as an emulsifier, and 986 parts by mass of water were stirred and mixed in a homomixer to obtain an emulsion. Immediately thereafter, a water-diluted solution of IPDA having an amino group content equivalent to 95% of the NCO groups was added to carry out chain extension, finally obtaining an aqueous urethane resin composition (2) with a solids content of 58% by mass.

[0079] (Example 3: Preparation of aqueous urethane resin composition (3)) An aqueous urethane resin composition (3) was obtained in the same manner as in Example 1, except that the blending amount of the polycarbonate polyol (PC-1) used in Example 1 was changed to 800 parts by mass and the blending amount of the polycarbonate polyol (PC-2) used in Example 1 was changed to 200 parts by mass.

[0080] Example 4 Preparation of Aqueous Urethane Resin Composition (4) In a four-neck flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 500 parts by mass of polycarbonate polyol (PC-1), 500 parts by mass of polycarbonate polyol (PC-4) obtained in Synthesis Example 4, 35 parts by mass of PEG, 184 parts by mass of H12MDI, and 67 parts of isophorone diisocyanate were reacted at 100°C in the presence of 0.1 part by mass of stannous octoate under a nitrogen stream until the NCO% reached 2.9%, to obtain a urethane prepolymer.

[0081] Next, the urethane prepolymer heated to 70°C, 64 parts by mass of a polypropylene-polyethylene copolymer ("Pluronic (registered trademark) L-64" manufactured by ADEKA Corporation) as an emulsifier, and 985 parts by mass of water were stirred and mixed in a homomixer to obtain an emulsion. Immediately thereafter, a water-diluted solution of IPDA having an amino group content equivalent to 95% of the NCO groups was added to carry out chain extension, finally obtaining an aqueous urethane resin composition (4) with a solids content of 58% by mass.

[0082] Example 5 Preparation of Aqueous Urethane Resin Composition (5) In a four-neck flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 500 parts by mass of polycarbonate polyol (PC-1), 500 parts by mass of polycarbonate polyol (PC-5) obtained in Synthesis Example 5, 35 parts by mass of PEG, 184 parts by mass of H12MDI, and 51 parts by mass of hexamethylene diisocyanate were reacted under a nitrogen stream at 100°C in the presence of 0.1 parts by mass of stannous octoate until the NCO% reached 3.0%, to obtain a urethane prepolymer.

[0083] Next, the urethane prepolymer heated to 70°C, 65 parts by mass of NEOGEN S-20F, and 982 parts by mass of water were stirred and mixed in a homomixer to obtain an emulsion. Immediately thereafter, a water-diluted solution of isophoronediamine (IPDA) having an amino group content equivalent to the molar amount of the NCO groups was added to carry out chain extension, finally obtaining an aqueous urethane resin composition (5) with a solids content of 57% by mass.

[0084] Example 6 Preparation of Aqueous Urethane Resin Composition (6) An aqueous urethane resin composition (6) was obtained in the same manner as in Example 1, except that the amount of polycarbonate polyol (PC-1) used in Example 1 was changed to 300 parts by mass and the polycarbonate polyol (PC-2) was changed to 700 parts by mass of the polycarbonate polyol (PC-6) obtained in Synthesis Example 6.

[0085] Example 7: Preparation of aqueous urethane resin composition (7) In a nitrogen-purged four-neck flask equipped with a stirrer, a reflux condenser, and a thermometer, 300 parts by mass of polycarbonate polyol (PC-1), 700 parts by mass of polycarbonate polyol (PC-6), 300 parts by mass of methyl ethyl ketone, and 11 parts by mass of 2,2-dimethylolpropionic acid were added and thoroughly stirred and mixed. After stirring and mixing, 262 parts by mass of H12MDI and 0.03 parts by mass of bismuth carboxylate were added, and the mixture was reacted at 75°C for approximately 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at the molecular end. Next, 8.0 parts by mass of triethylamine was added to the methyl ethyl ketone solution of the urethane prepolymer obtained by the above method to neutralize the carboxyl groups in the urethane prepolymer, followed by the addition of 1,800 parts by mass of ion-exchanged water, followed by the addition of IPDA in an amount of amino groups equivalent to the molar amount of NCO groups, and the mixture was allowed to react. After the reaction was completed, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous urethane resin composition (7) having a final solid content of 42% by mass.

[0086] Example 8 Preparation of Aqueous Urethane Resin Composition (8) In a four-neck flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 1,000 parts by mass of polycarbonate polyol (PC-3), 32 parts by mass of PEG, and 175 parts by mass of H12MDI were reacted at 100°C in the presence of 0.1 parts by mass of stannous octoate under a nitrogen stream until the NCO% reached 2.0%, thereby obtaining a urethane prepolymer.

[0087] Next, the urethane prepolymer heated to 70°C, 61 parts by mass of NEOGEN S-20F, and 951 parts by mass of water were stirred and mixed in a homomixer to obtain an emulsion. Immediately thereafter, a water-diluted solution of isophoronediamine (IPDA) having an amino group content equivalent to the molar amount of the NCO groups was added to carry out chain extension, finally obtaining an aqueous urethane resin composition (8) with a solids content of 57% by mass.

[0088] Comparative Example 1: Preparation of aqueous urethane resin composition (R1) An aqueous urethane resin composition (R1) was obtained in the same manner as in Example 1, except that the polycarbonate polyols (PC-1) and (PC-2) used in Example 1 were changed to polycarbonate polyol (PC-1) and the blending amount was changed to 1,000 parts by mass.

[0089] Comparative Example 2: Preparation of aqueous urethane resin composition (R2) An aqueous urethane resin composition (R2) was obtained in the same manner as in Example 1, except that the polycarbonate polyols (PC-1) and (PC-2) used in Example 1 were changed to polycarbonate polyol (PC-6) and the blending amount was changed to 1,000 parts by mass.

[0090] Comparative Example 3: Preparation of aqueous urethane resin composition (R3) An aqueous urethane resin composition (R3) was obtained in the same manner as in Example 1, except that the polycarbonate polyols (PC-1) and (PC-2) used in Example 1 were changed to polycarbonate polyol (PC-2) and the blending amount was changed to 1,000 parts by mass.

[0091] Comparative Example 4: Preparation of aqueous urethane resin composition (R4) An aqueous urethane resin composition (R4) was obtained in the same manner as in Example 5, except that the polycarbonate polyols (PC-1) and (PC-5) used in Example 5 were changed to polycarbonate polyol (PC-1) and the blending amount was changed to 1,000 parts by mass.

[0092] Comparative Example 5: Preparation of Aqueous Urethane Resin Composition (R5) Into a nitrogen-substituted vessel equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, 300 parts by mass of polycarbonate polyol (PC-2) was added, and dehydration was carried out at 120°C to 130°C under a reduced pressure of 0.095 MPa. After dehydration, 124 parts by mass of DMF was added and thoroughly stirred and mixed while cooling to 50°C. After stirring and mixing, 75 parts by mass of H12MDI and 0.2 parts by mass of stannous octoate were added and reacted at 75°C to obtain an organic solvent solution of a urethane prepolymer having an isocyanate group at the molecular end. Next, 1,040 parts by mass of DMF was added to the organic solvent solution of the urethane prepolymer, and the mixture was cooled to 35°C. 14 parts by mass of IPDA was added, and the polyurethane resin was chain-extended by stirring and mixing. Next, 1.5 parts by mass of N,N-dibutylamine was added and mixed to obtain an aqueous urethane resin composition (R5) having a nonvolatile content of 25% by mass and a viscosity of 300 dPa·s.

[0093] The aqueous urethane resin compositions (1) to (8) and (R1) to (R5) obtained in the above Examples and Comparative Examples were evaluated as follows.

[0094] [Method for evaluating chemical resistance] A mixture liquid obtained by blending 100 parts by mass of the aqueous urethane resin composition prepared in each of the Examples and Comparative Examples with 10 parts by mass of a black pigment ("Dilac HS-9530" manufactured by DIC Corporation) and 1 part by mass of a thickener ("Hydran Assister T10" manufactured by DIC Corporation) was applied to a flat release paper ("DN-TP-155T" manufactured by Ajinomoto Co., Inc.) so that the film would have a dry thickness of 30 μm, and the mixture was dried at 70° C. for 2 minutes and then at 120° C. for 2 minutes to obtain a surface layer. Next, a blended liquid containing 100 parts by mass of a urethane resin composition for forming an adhesive layer ("HYDRAN WLA-515AR" manufactured by DIC Corporation), 1 part by mass of a thickener ("HYDRAN ASISTOR T10" manufactured by DIC Corporation), and 9 parts by mass of a polyisocyanate crosslinking agent ("HYDRAN ASISTOR C5" manufactured by DIC Corporation) was applied to the surface layer so that the film thickness after drying would be 50 μm, and the mixture was dried at 70°C for 3 minutes. Immediately after drying, a polyurethane-impregnated nonwoven fabric was attached, followed by heat treatment at 120°C for 2 minutes and then aging at 50°C for 2 days. The release paper was then peeled off to obtain synthetic leather. Three to four drops of oleic acid were dropped on the surface of this synthetic leather, which was then allowed to stand at 80°C for 24 hours before being removed. The oleic acid adhering to the surface was lightly wiped off, and the change in appearance was visually observed and evaluated according to the following evaluation criteria.

[0095] A: No change. B: Slight swelling. C: Great swelling.

[0096] [Method for evaluating low-temperature flexibility] Synthetic leathers were prepared in the same manner as in the above-mentioned method for evaluating chemical resistance. The resulting synthetic leathers were then subjected to a flex test using a flexometer (-10°C, 100 times per minute), and the number of times until cracks appeared on the surface of the synthetic leather was measured. The test was evaluated according to the following criteria.

[0097] A: 60,000 times or more. B: 30,000 times or more but less than 60,000 times. C: Less than 30,000 times.

[0098] Tables 2 and 3 show the compositions and evaluation results of the aqueous urethane resin compositions (1) to (8) and (R1) to (R5) obtained in the above examples and comparative examples.

[0099]

[0100]

[0101] Examples 1 to 8 shown in Table 1 are examples in which the aqueous urethane resin composition of the present invention was used. It was confirmed that these aqueous urethane resin compositions had excellent chemical resistance and low-temperature flexibility.

[0102] On the other hand, Comparative Examples 1 to 5 shown in Table 2 are examples in which the amount of the diol compound having 2 to 4 carbon atoms used in the raw material diol compound of the polycarbonate polyol is outside the range of 10 to 90 mol %. It was confirmed that these aqueous urethane resin compositions do not have both chemical resistance and low-temperature flexibility.

Claims

1. An aqueous urethane resin composition comprising a urethane resin (A) and an aqueous medium (B), wherein the urethane resin (A) comprises, as essential reaction raw materials, a polyol compound (a1) containing a polycarbonate polyol (a1-1) and a polyisocyanate compound (a2), the polycarbonate polyol (a1-1) comprising a polycarbonate polyol whose essential raw material is a diol compound having 2 to 4 carbon atoms, and the amount of the diol compound having 2 to 4 carbon atoms used is in the range of 10 to 90 mol % of the raw material diol compound for the polycarbonate polyol (a1-1).

2. The urethane resin composition according to claim 1, wherein the polycarbonate polyol (a1-1) is at least one member selected from the group consisting of polycarbonate polyol (a1-1-1) which is a reaction product of a carbonate ester and / or phosgene with a diol compound having 2 to 4 carbon atoms; copolymeric polycarbonate polyol (a1-1-2) which contains, as essential raw materials, a carbonate ester and / or phosgene with a diol compound having 2 to 4 carbon atoms and a diol compound having 5 or more carbon atoms; and polycarbonate polyol (a1-1-3) which contains, as essential raw materials, a carbonate ester and / or phosgene with a diol compound having 5 or more carbon atoms.

3. The aqueous urethane resin composition according to claim 1, wherein the polycarbonate polyol (a1-1) is a bio-based polycarbonate polyol.

4. The aqueous urethane resin composition according to claim 1, wherein the urethane resin (A) further contains a chain extender (a3).

5. Synthetic leather characterized by having a layer formed from the aqueous urethane resin composition according to any one of claims 1 to 4.

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