Aqueous urethane resin composition, coating agent, and article

Abstract

To provide an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, thermal discoloration resistance, flexibility, heat resistance and moist heat resistance, a coating agent containing the aqueous urethane resin composition, and an article having a coating film of the coating agent.SOLUTION: The aqueous urethane resin composition containing a urethane resin (A) and an aqueous medium (B) is used. The urethane resin (A) uses a polyol compound (a1) containing a polycarbonate polyol, a polyisocyanate compound (a2), a compound (a3) having a hydrophilic group, a polyamine (a4), and hydrazine (a5) as essential reaction raw materials. The polyamine (a4) has two primary amino groups and one or more secondary amino groups.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aqueous urethane resin composition, a coating agent, and an article. [Background technology]

[0002] Urethane resin compositions generally have good adhesion to substrates and are capable of forming flexible coating films, and are therefore used in a variety of applications including coating agents and adhesives.

[0003] In particular, in applications involving synthetic leather for automobile interior materials such as car seats and headrests, the replacement of solvent-based urethane resins with water-based urethane resins is progressing from the viewpoints of reducing VOCs, reducing odors, eliminating concerns about toxicity due to solvents, etc. From another perspective, for example, in airbag coating applications, the use of urethane resin compositions is being considered in place of the silicone resins that have traditionally been used (e.g., Patent Document 1), and furthermore, replacement with water-based urethane resin compositions that emit less carbon dioxide is being considered.

[0004] The water-based urethane resins used in these products are required to have durability equivalent to that of solvent-based urethane resins, but because the resin itself contains a hydrophilic component or an emulsifier component, the durability of the resin alone tends to be low. Furthermore, the film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance are insufficient, and the performance requirements that have been increasing recently have not been met.

[0005] Therefore, there has been a demand for a material that has even better film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-265863 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance; a coating agent containing the aqueous urethane resin composition; and an article having a coating film of the coating agent. [Means for solving the problem]

[0008] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a specific urethane resin that uses a specific polyamine and hydrazine, and have completed the present invention.

[0009] Specifically, the present invention relates to an aqueous urethane resin composition comprising a urethane resin (A) and an aqueous medium (B), wherein the urethane resin (A) contains, as essential reaction raw materials, a polyol compound (a1) containing a polycarbonate polyol, a polyisocyanate compound (a2), a compound (a3) ​​having a hydrophilic group, a polyamine (a4), and hydrazine (a5), and the polyamine (a4) has two primary amino groups and one or more secondary amino groups; a coating agent containing the aqueous urethane resin composition; and an article having a coating film of the coating agent. [Effects of the Invention]

[0010] The aqueous urethane resin composition of the present invention has excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance, and therefore can be suitably used as a coating agent. DETAILED DESCRIPTION OF THE INVENTION

[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) used contains, as essential raw materials, a polyol compound (a1), a polyisocyanate compound (a2), a compound having a hydrophilic group (a3), a polyamine (a4), and hydrazine (a5).

[0013] As the polyol compound (a1), a polycarbonate polyol is used as an essential component.

[0014] Examples of the polycarbonate polyol include polycarbonate polyols obtained by reacting a carbonate ester and / or phosgene with a diol compound.

[0015] 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.

[0016] Examples of the diol compound include aliphatic diol compounds such as ethylene glycol, diethylene 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, 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 can be used alone or in combination of two or more.

[0017] The number average molecular weight of the polycarbonate polyol is preferably in the range of 300 to 10,000, more preferably in the range of 1,000 to 3,000, since an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance 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).

[0018] As the polyol compound (a1), if necessary, polyol compounds other than the polycarbonate polyols (hereinafter abbreviated as "other polyol compounds") can also be used in combination.

[0019] Examples of the other polyol compounds include polyester polyols, polyether polyols, polybutadiene polyols, etc. These polyol compounds can be used alone or in combination of two or more.

[0020] Examples of the polyester polyol include those obtained by esterifying a polycarboxylic acid with a polyhydric alcohol.

[0021] 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.

[0022] 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-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, and neopentyl glycol. These polyhydric alcohols can be used alone or in combination of two or more.

[0023] 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, tin 2-ethylhexanoate, 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.

[0024] 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.

[0025] 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 5,000, since an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance can be obtained.

[0026] The content of the other polyol compounds in the polyol compound (a1) is preferably in the range of 0 to 90% by mass.

[0027] The content of the polyol compound (a1) in the raw materials of the urethane resin (A) is preferably in the range of 50 to 95 mass %, more preferably in the range of 65 to 85 mass %, because an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance can be obtained.

[0028] 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, tetramethylxylylene diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate; and alicyclic diisocyanates such as norbornane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and dicyclohexylmethane diisocyanate. These polyisocyanate compounds can be used alone or in combination of two or more.

[0029] The content of the polyisocyanate compound (a2) in the raw materials of the urethane resin (A) is preferably in the range of 5 to 40 mass %, more preferably in the range of 10 to 30 mass %, because an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance can be obtained.

[0030] Examples of the compound (a3) ​​having a hydrophilic group include a compound having a carboxyl group as the hydrophilic group, a compound having a sulfonic acid group as the hydrophilic group, and a compound having a polyalkylene oxide structure as the hydrophilic group.

[0031] Examples of the compound having a carboxyl group as the hydrophilic group include compounds having a carboxyl group such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2′-dimethylolvaleric acid, and polyol compounds obtained by esterifying the compounds having a carboxyl group.

[0032] Examples of the compound having a sulfonic acid group as the hydrophilic group include diamines or polyamines containing an alkali metal sulfonate group, such as an alkali metal salt of N-(2-aminoethyl)-2-aminoethanesulfonic acid. Examples of the compound having a sulfonic acid group as the hydrophilic group include polyol compounds obtained by esterifying the polyhydric alcohol with a compound having a sulfonic acid group, such as 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, or 5[4-sulfophenoxy]isophthalic acid.

[0033] Examples of the compound having a polyalkylene oxide structure as the hydrophilic group include polyethylene glycol, polypropylene glycol, a copolymer of ethylene oxide and propylene oxide, a copolymer of ethylene oxide and butylene oxide, a copolymer of ethylene oxide and another alkylene oxide, and monoalkyl ethers thereof.

[0034] These compounds (a3) ​​having a hydrophilic group can be used alone or in combination of two or more kinds.

[0035] The polyamine (a4) used must have two primary amino groups and one or more secondary amino groups.

[0036] The number of the secondary amino groups in one molecule is preferably 1 to 5, and more preferably 1 to 3, since an aqueous urethane resin composition can be obtained that can form a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance.

[0037] Examples of the polyamine (a4) include diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine, and 2-aminoethyl-3-aminopropylamine. These polyamines can be used alone or in combination of two or more. Furthermore, diethylenetriamine and triethylenetetramine are preferred, and diethylenetriamine is more preferred, because they provide an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance.

[0038] The content of the polyamine (a4) in the raw materials for the urethane resin (A) is preferably in the range of 0.01 to 1.50 mass%, more preferably 0.20 to 1.20 mass%, because an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance can be obtained.

[0039] As the hydrazine (a5), hydrazine monohydrate, hydrazine acid addition salts such as hydrazine hydrochloride and hydrazine sulfate can also be used.

[0040] The equivalent ratio [(a4) / (a5)] of the polyamine (a4) to the hydrazine (a5) is preferably in the range of 99 / 1 to 1 / 99, more preferably in the range of 80 / 20 to 20 / 80, since an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance can be obtained.

[0041] The acid value of the urethane resin (A) is preferably in the range of 5 to 25 mgKOH / g, more preferably in the range of 10 to 20 mgKOH / g, since an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance can be obtained.

[0042] The flow initiation temperature of the urethane resin (A) is preferably 180°C or higher, since this allows for the production of an aqueous urethane resin composition capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance.

[0043] The average particle size of the urethane resin (A) is preferably in the range of 10 to 500 nm, more preferably in the range of 20 to 300 nm, since an aqueous urethane resin composition can be obtained that can form a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance.

[0044] The method for producing the urethane resin (A) is not particularly limited, and any method may be used. For example, the urethane resin (A) may be produced by reacting all of the reaction raw materials, including the polyol compound (a1), the polyisocyanate compound (a2), the compound (a3) ​​having a hydrophilic group, the polyamine (a4), and the hydrazine (a5), all at once, or by reacting the reaction raw materials sequentially. These reactions are preferably carried out at a temperature of 50 to 100°C for 3 to 10 hours.

[0045] 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.

[0046] The method for producing the aqueous urethane resin composition is not particularly limited, and any method may be used for production, such as a method (Method 1) of mixing the urethane resin (A) with the aqueous medium (B) to obtain the aqueous urethane resin composition, or a method (Method 2) of synthesizing a prepolymer by reacting a polyol compound (a1), a polyisocyanate compound (a2), and a compound (a3) ​​having a hydrophilic group, dispersing the prepolymer in the aqueous medium (B), and then reacting the prepolymer with a polyamine (a4) and a hydrazine (a5).

[0047] In the above (Method 1) and (Method 2), a neutralizing agent can also be used if necessary.

[0048] Examples of methods for mixing the urethane resin (A) and the aqueous medium (B) include methods using a reaction vessel equipped with a stirring blade; 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, a Bodeta-type kneader, or the like; 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.

[0049] The mass ratio of the urethane resin (A) to the aqueous medium (B) [(A) / (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 capable of forming a coating film having excellent film-forming properties, heat discoloration resistance, flexibility, heat resistance, and moist heat resistance can be obtained.

[0050] The aqueous urethane resin composition of the present invention may contain other additives as needed.

[0051] Examples of the other additives include emulsifiers, thickeners, urethane catalysts, fillers, flame retardants, leveling agents, antiblocking agents, etc. These additives can be used alone or in combination of two or more.

[0052] Examples of the emulsifier include nonionic emulsifiers such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrylphenyl ether, polyoxyethylene sorbitol tetraoleate, and polyoxyethylene-polyoxypropylene copolymer; anionic emulsifiers such as fatty acid salts such as sodium oleate, alkyl sulfate ester salts, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, polyoxyethylene alkyl sulfates, sodium alkanesulfonates, and sodium alkyldiphenyl ether sulfonates; and cationic emulsifiers such as alkylamine salts, alkyltrimethylammonium salts, and alkyldimethylbenzylammonium salts. These emulsifiers can be used alone or in combination of two or more.

[0053] Examples of the thickener include associative and acid thickeners.

[0054] Examples of the urethane catalyst include organotin catalysts and bismuth catalysts.

[0055] Examples of the filler include calcium carbonate and silica.

[0056] Examples of the flame retardant include phosphorus-based flame retardants.

[0057] Examples of the leveling agent include silicone-based leveling agents.

[0058] Examples of the anti-blocking agent include acrylic agents and cellulose ester agents.

[0059] The coating agent of the present invention contains the aqueous urethane resin composition.

[0060] Examples of substrates onto which the coating agent can be applied to form a coating film include glass substrates, plastic substrates, metal substrates, paper substrates, wood substrates, fibrous substrates, etc. Substrates with a porous structure, such as urethane foam, can also be used.

[0061] Examples of plastic substrates that can be used include polycarbonate substrates, polyester substrates, acrylonitrile-butadiene-styrene resin substrates, polyacrylic substrates, polystyrene substrates, polyurethane substrates, epoxy resin substrates, polyvinyl chloride substrates, and polyamide substrates.

[0062] Examples of the metal substrate that can be used include plated steel sheets such as zinc-plated steel sheets and aluminum-zinc alloy steel sheets, iron sheets, aluminum sheets, aluminum alloy sheets, electromagnetic steel sheets, copper sheets, and stainless steel sheets.

[0063] The substrate may be made of the above-mentioned material and may be flat or have a curved portion, or may be a substrate made of fibers such as nonwoven fabric.

[0064] The coating agent of the present invention can form a coating film, for example, by applying it directly to the surface of the substrate or to the surface of a substrate on which a primer layer or the like has been previously formed, and then drying it.

[0065] Alternatively, the coating agent may be applied to a release paper, followed by drying and curing to form a coating film on the surface of the release paper, and then an adhesive or pressure-sensitive adhesive may be applied to the coating film, which may then be attached to a substrate made of fibers such as nonwoven fabric, and the release paper may be peeled off, thereby laminating a coating film formed using the coating agent on the surface of a desired substrate.

[0066] Examples of methods for applying the coating agent to the substrate include spraying, curtain coating, flow coating, roll coating, knife coating, brush coating, and dipping.

[0067] The thickness of the coating film that can be formed using the coating agent of the present invention can be adjusted appropriately depending on the application of the substrate, but is usually preferably about 0.1 μm to 100 μm.

[0068] The articles of the present invention include those having a coating film of the coating agent, and specific examples thereof include airbags, synthetic leather, artificial leather, paints, etc. [Example]

[0069] 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.

[0070] (Example 1: Synthesis of aqueous urethane resin composition (1)) A four-neck flask equipped with a thermometer, stirrer, reflux condenser, and nitrogen inlet tube was charged with 100 parts by weight of polycarbonate diol (UBE Corporation's "ETERNACOLL UH-200J," number-average molecular weight 2000), 4.75 parts by weight of 2,2-dimethylolpropionic acid, and 86.8 parts by weight of methyl ethyl ketone, and the mixture was dissolved uniformly. Next, 25.5 parts by weight of isophorone diisocyanate was added and the reaction was continued at 80°C until the NCO concentration reached 1.13%, yielding a urethane resin (1) having NCO groups. The mixture was then cooled to 50°C, and 312.3 parts by weight of ion-exchanged water and 4.30 parts by weight of triethylamine as a neutralizer were added to emulsify the system uniformly. Then, 1.15 parts by weight of 80% hydrazine and 0.54 parts by weight of diethylenetriamine, which had been premixed, were added to extend the chain. Finally, the methyl ethyl ketone in the system was recovered by vacuum degassing, yielding an aqueous urethane resin composition (1) having a solid content of 35% by mass, an average particle size of 46 nm, and an acid value (based on the solid content) of 14.7 mgKOH / g.

[0071] (Examples 2 to 6: Preparation of aqueous urethane resin compositions (2) to (6)) Aqueous urethane resin compositions (2) to (6) were obtained in the same manner as in Example 1, except that the compositions and blending amounts were changed to those shown in Table 1.

[0072] (Comparative Examples 1 to 3: Preparation of aqueous urethane resin compositions (R1) to (R3)) Aqueous urethane resin compositions (R1) to (R3) were obtained in the same manner as in Example 1, except that the compositions and blending amounts were changed to those shown in Table 1.

[0073] The aqueous urethane resin compositions (1) to (6) and (R1) to (R3) obtained in the above examples and comparative examples were evaluated as follows.

[0074] [Method for evaluating film-forming properties] A thickener (ADEKA Corporation's "ADEKA NOL UH-420") was added to each aqueous urethane resin composition obtained in the Examples and Comparative Examples so that the viscosity of the resulting mixture was 5,000 to 10,000 mPa·s (25°C). The mixture was stirred at 2,000 rpm for 3 minutes using a disperser, homogenized, and degassed. The resulting mixture was then coated onto release paper (LINTEC Corporation's "EK-100D") using a knife coater and dried at 70°C for 2 minutes and then at 120°C for 2 minutes to obtain a film (1) with a thickness of approximately 40 μm. The appearance of the resulting film (1) was evaluated according to the following criteria.

[0075] A: A film was obtained in which the water had dried and the film was free of cracks. B: The water has not dried and / or cracks have been observed in the coating.

[0076] [Method for evaluating heat discoloration resistance] A thickener (ADEKA CORPORATION's "ADEKA NOL UH-420") was added to each aqueous urethane resin composition obtained in the Examples and Comparative Examples so that the viscosity of the blended solution was 5,000 to 10,000 mPa·s (25°C). The mixture was stirred at 2,000 rpm for 3 minutes using a disperser, uniformly dissolved, and degassed. The resulting blended solution was then coated onto PET (Toray Industries, Inc.'s polyester film Lumirror #125T60) using a knife coater and dried at 70°C for 2 minutes and then 120°C for 2 minutes, yielding a PET coated product with a film thickness of approximately 40 μm. The PET coated product was then exposed at 120°C for 400 hours with the coated side facing up. After exposure, the PET coated product was attached to a white backing card and its discoloration (ΔE *ab: PET coated object before discoloration pasted onto a white backing (reference) was measured using a spectrophotometer CM-5 (Konica Minolta) using the reflection method, a target mask of φ30 mm, and an observation light source of D65.

[0077] [Flexibility evaluation method] A thickener (ADEKA CORPORATION's "ADEKA NOL UH-420") was added to each aqueous urethane resin composition obtained in the examples and comparative examples to adjust the viscosity of the resulting mixture to 5,000 to 10,000 mPa·s (25°C). The mixture was stirred at 2,000 rpm for 3 minutes using a disperser to dissolve uniformly and degas the resulting mixture. The resulting mixture was then coated onto flat release paper (LINTEC CORPORATION's "EK-100D") to a dry thickness of 40 μm, and dried at 70°C for 2 minutes and then 120°C for 2 minutes to obtain a polyurethane film. The polyurethane film was then cut into strips 5 mm wide and 50 mm long to prepare test specimens. A tensile test was performed on this test piece using a tensile testing machine (Shimadzu Corporation, "Autograph AG-I") under conditions of a chuck distance of 40 mm, a tensile speed of 10 mm / sec, and a temperature of 23°C, and the stress at 100% elongation (100% modulus, hereinafter abbreviated as "100% M") was measured and evaluated according to the following criteria.

[0078] A: 100% M was less than 4.0 MPa. B: 100% M was 4.0 MPa or more.

[0079] [Heat resistance evaluation method] In the present invention, the heat resistance was evaluated based on the shape retention and heat resistance strength of the heat-resistant film.

[0080] <Method for evaluating heat-resistant film shape retention> The film (1) was fixed to a frame made of cardboard so that it could be exposed from both sides, and exposed for 400 hours at 120° C. The state of the film after exposure was observed and evaluated according to the following criteria.

[0081] A: The film maintained its shape. B: The film dissolved and could not maintain its shape.

[0082] <Evaluation method for heat resistance strength> The film used to evaluate the shape retention of the heat-resistant film was exposed to 120°C for 400 hours and cut into strips of 5 mm width and 50 mm length to prepare test pieces. A tensile test was performed on these test pieces using a tensile tester (Shimadzu Corporation's "Autograph AG-I"; chuck distance: 40 mm, tensile speed: 10 mm / sec, temperature: 23°C), and the stress (tensile strength) at break was measured and evaluated according to the following criteria.

[0083] A: After the test, the tensile strength of the film was retained at 70% or more compared to the initial tensile strength. B: The tensile strength of the film after the test was retained at less than 70% of the initial tensile strength.

[0084] [Method for evaluating humidity and heat resistance] In the present invention, the moist heat resistance was evaluated based on the moist heat resistant film shape retention and moist heat resistant strength.

[0085] <Method for evaluating shape retention of heat and humidity resistant film> The film (1) was fixed to a frame made of cardboard so that it could be exposed from both sides, and exposed for 400 hours at 80°C and 95% RH. The film condition after exposure was observed and evaluated according to the following criteria.

[0086] A: The film maintained its shape. B: The film dissolved and could not maintain its shape.

[0087] <Method for evaluating humidity and heat resistance> The film used to evaluate the shape retention of the moist heat-resistant film was exposed to 80°C and 95% RH for 400 hours and cut into strips of 5 mm width and 50 mm length to prepare test pieces. A tensile test was performed on these test pieces using a tensile testing machine (Shimadzu Corporation's "Autograph AG-I"; chuck distance: 40 mm, tensile speed: 10 mm / sec, temperature: 23°C), and the stress (tensile strength) at break was measured and evaluated according to the following criteria.

[0088] A: After the test, the tensile strength of the film was retained at 70% or more compared to the initial tensile strength. B: The tensile strength of the film after the test was retained at less than 70% of the initial tensile strength.

[0089] [Method for measuring flow temperature] The flow starting temperature of the film (1) was measured using a flow tester "CFT-500A" manufactured by Shimadzu Corporation (using a die with a diameter of 1 mm and a length of 1 mm, a load of 98 N, and a temperature rise rate of 3°C / min).

[0090] Table 1 shows the compositions and evaluation results of the aqueous urethane resin compositions (1) to (6) and (R1) to (R3) obtained in the above examples and comparative examples.

[0091] [Table 1]

[0092] In Table 1, "UH-200J" represents polycarbonate diol ("ETERNACOLL UH-200J" manufactured by UBE Corporation, number average molecular weight 2000).

[0093] In Table 1, "UH-100J" represents polycarbonate diol ("ETERNACOLL UH-100J" manufactured by UBE Corporation, number average molecular weight 1000).

[0094] In Table 1, "T4692" represents polycarbonate diol ("DURANOL T4692" manufactured by Asahi Kasei Corporation, number average molecular weight 2000).

[0095] The acid values ​​in Table 1 are values ​​obtained by calculation from the raw material charging ratios of the aqueous urethane resin composition.

[0096] The viscosities in Table 1 were measured by placing the aqueous urethane resin composition obtained in a 200 g glass bottle, adjusting the temperature to 25°C in a thermostatic water bath, and then using a Toki Sangyo BM-type viscometer TVB-10M at 60 rpm with rotor No. 1 (changing to rotor No. 2 for viscosity values ​​above 100 mPa s).

[0097] The particle sizes in Table 1 were measured as the volume average particle size using a laser diffraction / scattering particle size distribution analyzer (Microtrac UPA-EX150 manufactured by Nikkiso Co., Ltd.) with water as the dispersion liquid, a solvent refractive index of 1.33, and a particle refractive index of 1.51.

[0098] [Table 2]

[0099] In Table 2, "-" indicates that evaluation was not possible. Regarding the heat resistance strength and moist heat resistance strength of Comparative Examples 4 and 6, the film shape could not be maintained after the heat resistance test and moist heat resistance test, and the tensile strength could not be measured, so evaluation was not possible. Furthermore, in Comparative Example 5, a film could not be formed, so evaluation of flexibility, heat resistance, and moist heat resistance was not possible.

Claims

1. An aqueous urethane resin composition comprising a urethane resin (A) and an aqueous medium (B), The urethane resin (A) is a polyol compound (a1) containing a polycarbonate polyol; Polyisocyanate compound (a2), a compound (a3) ​​having a hydrophilic group; Polyamines (a4), and hydrazine (a5) as essential reaction raw materials, An aqueous urethane resin composition, characterized in that the polyamine (a4) has two primary amino groups and one or more secondary amino groups.

2. 2. The aqueous urethane resin composition according to claim 1, wherein the equivalent ratio [(a4) / (a5)] of the polyamine (a4) to the hydrazine (a5) is in the range of 99 / 1 to 1 / 99.

3. 2. The aqueous urethane resin composition according to claim 1, wherein the urethane resin (A) has an acid value of the solid content in the range of 5 to 25 mgKOH / g.

4. 2. The aqueous urethane resin composition according to claim 1, wherein the urethane resin (A) has a flow initiation temperature of 180°C or higher.

5. A coating agent comprising the aqueous urethane resin composition according to any one of claims 1 to 4.

6. An article having a coating film of the coating agent according to claim 5.

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