Polyurethane resin, curable composition, cured product, and adhesive

Abstract

Provided are a urethane resin and a curable composition capable of forming a cured product having excellent storage stability and adhesive properties. A polyurethane resin is used that is formed from a polyol compound (a1), a polyisocyanate compound (a2), and a compound (a3) having a cyano group as base materials.

Description

Technical Field

[0001] The present invention relates to a polyurethane resin, a curable composition, a cured product and an adhesive. Background Art

[0002] Polyurethane resins generally have good adhesion to substrates and can form soft coatings. Therefore, polyurethane resins have been used in various applications including coating agents and adhesives. In recent years, polyurethane resins have been increasingly used as adhesives for structures such as motor vehicles. As adhesives for structures, adhesives formed by combining bisphenol-type epoxy resins with blocked isocyanate resins obtained by using bisphenols such as o,o'-diallyl-bisphenol A as blocking agents are known (for example, see Patent Document 1). However, adhesives have insufficient storage stability and do not meet the performance requirements of the increasingly demanding physical properties of cured products (for example, adhesive properties).

[0003] Therefore, there is a demand for materials having excellent storage stability and adhesive properties.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent No. 5,278,257 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] An object of the present invention is to provide a polyurethane resin capable of forming a cured product having excellent storage stability and excellent adhesive properties, a curable composition containing the polyurethane resin, a cured product of the curable composition, and an adhesive comprising the curable composition.

[0009] Solutions for solving problems

[0010] The present inventors have conducted intensive studies to achieve this object and have therefore found that this object can be achieved by using a polyurethane resin formed from a polyol compound, a polyisocyanate compound, and a compound having a cyano group as basic raw materials.

[0011] Specifically, the present invention relates to a polyurethane resin formed from a polyol compound (a1), a polyisocyanate compound (a2), and a compound having a cyano group (a3) as basic raw materials, a curable composition containing the polyurethane resin, a cured product of the curable composition, and an adhesive comprising the curable composition.

[0012] Effects of the Invention

[0013] The polyurethane resin and curable composition of the present invention can form a cured product having excellent storage stability and excellent adhesive properties. Therefore, the polyurethane resin and curable composition can be used as a coating agent or an adhesive, and can be particularly suitably used as an adhesive. DETAILED DESCRIPTION

[0014] The basic raw materials of the polyurethane resin used in the present invention are a polyol compound (a1), a polyisocyanate compound (a2), and a compound having a cyano group (a3).

[0015] The example of polyol compound (a1) includes polyether polyols such as polypropylene glycol, polypropylene glycol and polytetramethylene glycol, polyester polyol, polycarbonate polyol, and acrylic polyol. Among these compounds, polyether polyol is preferred, and the polyol containing polyoxyethylene unit and polyoxypropylene unit is more preferred because it is possible to obtain a polyurethane resin and a curable composition that can form a cured product with excellent storage stability and excellent adhesion properties. Due to the polyoxyethylene unit contained, a certain amount of moisture can be introduced into the adhesive layer (cured product) during use as an adhesive, thereby suppressing interfacial peeling even when peeling occurs, and due to high cohesive fracture (cohesive fracture), the function of the adhesive can be fully exerted. In addition, the polyol containing polyoxyethylene unit and polyoxypropylene unit has a more excellent performance balance as an adhesive compared with the polyol containing polyoxytetramethylene unit, which has insufficient flexibility and is likely to cause interfacial peeling. Polyoxyethylene unit and polyoxypropylene unit may not be present in one molecule. For example, a polyol containing only a polyoxyethylene unit and a polyol containing only a polyoxypropylene unit may be used in combination and reacted with the polyisocyanate compound (a2) described below.

[0016] Examples of polyols containing polyoxyethylene units and polyoxypropylene units include polyoxyethylene-polyoxypropylene copolymers. From the perspective of achieving superior adhesive properties, polyoxyethylene-polyoxypropylene copolymers are preferably trifunctional or higher functional copolymers. From the perspective of achieving an excellent balance between adhesion to substrates and mechanical strength during use as an adhesive, the number of repeating oxyethylene units in the polyoxyethylene is preferably in the range of 2 to 10.

[0017] The mass ratio of the polyoxyethylene unit to the polyoxypropylene unit in the polyol containing the polyoxyethylene unit and the polyoxypropylene unit ((polyoxyethylene unit) / (polyoxypropylene unit)) is preferably in the range of 40 / 60 to 1 / 99, because a polyurethane resin and a curable composition capable of forming a cured product having excellent storage stability and excellent adhesive properties can be obtained.

[0018] The polyol containing polyoxyethylene units and polyoxypropylene units may contain units other than polyoxyethylene and polyoxypropylene (hereinafter referred to as "other units"). Examples of other units include units having one or two or more of the following as repeating units: aliphatic diols such as neopentane glycol; triols such as glycerol, triisobutane, 1,2,3-butanetriol, 1,2,3-pentanetriol, 2-methyl-1,2,3-propanetriol, 2-methyl-2,3,4-butanetriol, 2-ethyl-1,2,3-butanetriol, 2,3,4-pentanetriol, 2,3,4-hexanetriol, 4-propyl-3,4,5-heptanetriol, 2, 4-dimethyl-2,3,4-pentanetriol, pentamethylglycerol, pentaglycerol, 1,2,4-butanetriol, 1,2,4-pentanetriol, and trimethylolpropane; tetrahydric alcohols such as erythritol, pentaerythritol, 1,2,3,4-pentanethritol, 2,3,4,5-hexanetetraol, 1,2,3,5-pentanethritol, and 1,3,4,5-hexanetetraol; pentahydric alcohols such as adonitol, arabitol, and xylitol; and hexahydric alcohols such as sorbitol, mannitol, and idite.

[0019] In addition, from the viewpoint of better adhesion to the substrate and better physical properties of the cured product, it is preferred that the polyol compound (a1) contains a difunctional to tetrafunctional component, particularly a trifunctional component. The number average molecular weight of the polyol (a1) is preferably in the range of 1,000 to 5,000, and more preferably in the range of 2,000 to 4,000.

[0020] The polyisocyanate compound (a2) is preferably a compound having at least two isocyanate groups in one molecule. From the viewpoint of easily adjusting the molecular weight of the isocyanate prepolymer (A), the polyisocyanate compound (a2) is more preferably a compound having two to four isocyanate groups, and particularly preferably a diisocyanate, because a polyurethane resin and a curable composition capable of forming a cured product having excellent storage stability and excellent adhesive properties can be obtained.

[0021] Examples of the polyisocyanate compound (a2) include propane-1,2-diisocyanate, 2,3-dimethyl-2,3-diisocyanate, 2-methylpentane-2,4-diisocyanate, octane-3,6-diisocyanate, 3,3-dinitropentane-1,5-diisocyanate, octane-1,6-diisocyanate, 1,6-hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate, lysine diisocyanate, toluene diisocyanate, The polyisocyanate compound may be used alone or in combination of two or more thereof.

[0022] Among them, hexamethylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethane-4,4′-diisocyanate are preferred from the viewpoint of easy control of the reaction with the polyol compound (a1) and availability of raw materials, and isophorone diisocyanate is more preferred because a polyurethane resin and a curable composition capable of forming a cured product having excellent storage stability and excellent adhesive properties can be obtained.

[0023] From the viewpoint of easily adjusting the molecular weight of the prepolymer to be obtained and reducing unreacted polyisocyanate, the amount of the polyisocyanate compound (a2) used is preferably in the range of 1.80 to 3.50 mol in terms of isocyanate groups relative to 1 mol of the hydroxyl groups in the polyol compound (a1).

[0024] Examples of the compound (a3) having a cyano group include phenol compounds having a cyano group, oxime compounds having a cyano group, amine compounds having a cyano group, active methylene compounds having a cyano group, amide compounds having a cyano group, azole compounds having a cyano group, and alcohol compounds having a cyano group. The compound having a cyano group may be used alone, or two or more thereof may be used in combination.

[0025] The compound (a3) having a cyano group can be suitably used as a blocking agent.

[0026] As the blocking agent, a compound other than the compound (a3) having a cyano group (hereinafter referred to as "other blocking agent") can be used.

[0027] Examples of other blocking agents include active methylene compounds such as malonate diesters (diethyl malonate, etc.), acetylacetone, and acetoacetate esters (ethyl acetoacetate, etc.); oxime compounds such as acetone oxime, methyl ethyl ketoxime (MEKoxime), and methyl isobutyl ketoxime (MIBKoxime); monohydric alcohols such as methanol, ethanol, propanol, butanol, heptanol, hexanol, octanol, 2-ethylhexanol, isononanol, stearyl alcohol, or isomers thereof; diol derivatives such as methyl glycol, ethyl Ethylene glycol, ethyl diglycol, ethyl triglycol, butyl glycol, and butyl diglycol; amine compounds such as dicyclohexylamine; monophenol compounds such as phenol, cresol, ethylphenol, n-propylphenol, isopropylphenol, butylphenol, tert-butylphenol, octylphenol, nonylphenol, dodecylphenol, cyclohexylphenol, chlorophenol, and bromophenol; diphenol compounds such as resorcinol, catechol, hydroquinone, bisphenol A, bisphenol S, bisphenol F, and naphthol; ε-caprolactone and ε-caprolactam. Other blocking agents may be used alone, or two or more thereof may be used in combination.

[0028] Examples of the production method of the polyurethane resin include, but are not limited to, a method in which a polyol compound (a1) is reacted with a polyisocyanate compound (a2) so that the isocyanate group in the polyisocyanate compound (a2) is excessive relative to the hydroxyl group in the polyol compound (a1) to obtain a polyurethane prepolymer having an isocyanate group, and the excess isocyanate group is blocked using a compound (a3) having a cyano group.

[0029] The reaction of the polyol compound (a1) and the polyisocyanate compound (a2) is not particularly limited and can be carried out by a common urethane-forming reaction. The reaction temperature is preferably in the range of 40 to 140° C., and more preferably in the range of 60 to 130° C. A polyurethane polymerization catalyst may be used to promote the reaction.

[0030] Examples of polyurethane polymerization catalysts include organometallic compounds such as dioctyltin dilaurate, dibutyltin dilaurate, tin (II) octoate, stannous octoate, lead octoate, lead naphthenate, and zinc octoate, and tertiary amine compounds such as triethylenediamine and triethylamine. The polyurethane polymerization catalysts may be used alone or in combination of two or more.

[0031] The end-capping method using the compound (a3) having a cyano group can be carried out by a known end-capping reaction. The amount of the compound (a3) having a cyano group is preferably in the range of 1 to 2 equivalents, and more preferably in the range of 1.05 to 1.5 equivalents, relative to the excess isocyanate group, that is, the free isocyanate group.

[0032] The end-capping reaction using the end-capping agent (a3) is a method in which the end-capping agent (a3) is added in the final reaction of ordinary polyurethane polymerization. The end-capping agent (a3) can be added and reacted at an optional stage of polyurethane polymerization to become a blocked isocyanate prepolymer.

[0033] The method for adding the end-blocking agent (a3) may be a method in which the end-blocking agent is added when the polymerization is scheduled to be completed, a method in which the end-blocking agent is added in the early stages of polymerization, or a method in which a portion of the end-blocking agent is added in the early stages of polymerization and the remainder of the end-blocking agent is added when the polymerization is completed. It is preferred to add the end-blocking agent when the polymerization is completed. In this case, the predetermined polymerization completion time may be based on the isocyanate rate. The reaction temperature during the addition of the end-blocking agent is generally 50 to 150° C., and preferably 60 to 120° C. The reaction time is generally about 1 to 7 hours. In the reaction, a polyurethane polymerization catalyst may be added to promote the reaction. In the reaction, any amount of plasticizer may be added.

[0034] From the viewpoint of favorable handling during use of the curable composition as an adhesive, the weight average molecular weight of the blocked isocyanate prepolymer (A) is preferably in the range of 4,000 to 15,000, and more preferably in the range of 5,000 to 10,000. In the present invention, the weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC).

[0035] Epoxy resin (B) is not particularly limited, and various epoxy resins can be used. When epoxy resin is used as an adhesive, epoxy resin is preferably a liquid epoxy resin at room temperature. Examples thereof include bisphenol or diphenol type epoxy resins such as tetramethyl diphenol type epoxy resin, bisphenol A type epoxy resin, and bisphenol F type epoxy resin; aliphatic polyol polyglycidyl ethers such as butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, and glycerol triglycidyl ether; polyglycidyl compounds containing ring structures such as diglycidyl aniline, resorcinol diglycidyl ether, and hydrogenated bisphenol A diglycidyl ether; monofunctional glycidyl compounds containing ring structures such as alkylphenol monoglycidyl ether; and polyglycidyl ester compounds such as neodecanoic acid glycidyl ester. Among them, bisphenol or diphenol type epoxy resins are preferably used because polyurethane resins and curable compositions that can form cured products with excellent storage stability and excellent adhesive properties can be obtained. From the perspective of industrial availability, bisphenol type epoxy resins are preferred. In particular, the amount of bisphenol type epoxy resin is preferably 50% by mass or more, and more preferably 70% by mass or more relative to the total amount of epoxy resin (B). Each epoxy resin can be used alone, or two or more thereof can be used in combination.

[0036] Examples of bisphenol or diphenol type epoxy resins include those epoxy resins formed from various bisphenol compounds or diphenol compounds and epihalohydrin as resin raw materials. Specific examples thereof include epoxy resins represented by the following structural formula (1). Each bisphenol or diphenol type epoxy resin can be used alone, or two or more thereof can be used in combination.

[0037] [Formula 1]

[0038]

[0039] (wherein X is each independently a structural moiety represented by any of the following structural formulae (2-1) to (2-8), and n is a repetition number.)

[0040] [Formula 2]

[0041]

[0042] (where R 2 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R 3 are each independently an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

[0043] X in the structural formula (1) is a structural moiety represented by any of the structural formulas (2-1) to (2-8). The structural moieties of X in the molecule may be the same as or different from each other. Among them, the structural moiety represented by the general formula (2-1) or (2-2) is preferred because a curable composition capable of forming a cured product having excellent storage stability and excellent adhesive properties can be obtained.

[0044] Bisphenol type or diphenol type epoxy resin can be produced by various bisphenol compounds as above wherein or diphenol compounds and epihalohydrin as the method for resin raw material.The specific example of the method comprises wherein making the diglycidyl ether compound obtained by the reaction of bisphenol compounds or diphenol compounds and epihalohydrin further with the method (first method) of bisphenol compounds or diphenol compounds reacting, or wherein bisphenol compounds or diphenol compounds and epihalohydrin are reacted to directly obtain the method (second method) of epoxy resin.In described method, first method is preferred, because the method easily controls reaction and easily will be controlled to preferred value by the epoxide equivalent of the epoxy resin (B) obtained.

[0045] Examples of the bisphenol compound or diphenol compound used in the first or second method include compounds represented by any of the following structural formulae (3-1) to (3-8).

[0046] [Formula 3]

[0047]

[0048] (where R 2 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R 3 are each independently an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

[0049] The bisphenol compound or diphenol compound may be used alone, or two or more thereof may be used in combination. Among them, the compound represented by the general formula (3-1) or (3-2) is preferred because a curable composition capable of forming a cured product having excellent storage stability and excellent adhesive properties can be obtained.

[0050] In the first method, the mass ratio of the bisphenol compound or diphenol compound to the diglycidyl ether compound in the reaction is preferably in the range of 50 / 50 to 5 / 95. The reaction temperature is preferably about 120 to 160°C. A reaction catalyst such as tetramethylammonium chloride may be used.

[0051] The epoxy equivalent of the epoxy resin (B) is preferably within the range of 150 to 250 g / eq, and further preferably 160 to 200 g / eq, because a curable composition capable of forming a cured product having excellent storage stability and excellent adhesive properties can be obtained.

[0052] As the epoxy resin (B), a bisphenol-type or diphenol-type epoxy resin and a soft epoxy resin such as a urethane-modified epoxy resin or a rubber-modified epoxy resin may be used in combination as appropriate.

[0053] The structure of the polyurethane-modified epoxy resin is not particularly limited as long as it is a resin having a urethane bond and two or more epoxy groups in the molecule. Since a urethane bond and an epoxy group can be efficiently introduced into one molecule, it is preferred that the resin be obtained by reacting an epoxy compound containing a hydroxyl group with a urethane bond-containing compound having an isocyanate group, the urethane bond-containing compound having an isocyanate group being obtained by reacting a polyhydroxy compound with a polyisocyanate.

[0054] Examples of the polyol include polyether polyol, polyester polyol, adducts of hydroxycarboxylic acids and alkylene oxides, polybutadiene polyol, and polyolefin polyol.

[0055] The weight average molecular weight of the polyol is preferably in the range of 300 to 5,000, and more preferably in the range of 500 to 2,000.

[0056] Polyisocyanate is not particularly limited as long as it is a compound having two or more isocyanate groups. Examples of polyisocyanates include aromatic polyisocyanates and polyisocyanates having aromatic hydrocarbon groups. Among them, aromatic polyisocyanates are preferred. Examples of aromatic polyisocyanates include toluene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate.

[0057] Through the above reaction, a polyurethane prepolymer having a free isocyanate group at the end is obtained. The polyurethane prepolymer is reacted with an epoxy resin having at least one hydroxyl group in one molecule (for example, diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of aliphatic polyols, and glycidol) to obtain a polyurethane-modified epoxy resin.

[0058] The epoxy equivalent of the polyurethane-modified epoxy resin is preferably in the range of 200 to 250 g / eq.

[0059] The rubber modified epoxy resin is not particularly limited as long as it is an epoxy resin having two or more epoxy groups and a rubber backbone. Examples of the rubber forming the backbone include polybutadiene acrylonitrile rubber (NBR) and carboxyl terminated NBR (CTBN). The rubber modified epoxy resin can be used alone, or two or more thereof can be used in combination.

[0060] The epoxy equivalent of the rubber modified epoxy resin is preferably in the range of 200 to 350 g / eq. The production method of the rubber modified epoxy resin is not particularly limited. Examples thereof include methods for reacting the epoxy in rubber with a large amount of epoxy. The epoxy (e.g., epoxy resin) used to produce the rubber modified epoxy resin is not particularly limited.

[0061] Examples of the curing agent (C1) include polyamine compounds, amide compounds, acid anhydrides, phenolic hydroxyl group-containing resins, phosphorus compounds, imidazole compounds, imidazoline compounds, urea compounds, organic acid metal salts, Lewis acids, and amine complex salts.

[0062] Examples of the polyamine compound include aliphatic amine compounds such as trimethylenediamine, ethylenediamine, N,N,N',N'-tetramethylethylenediamine, pentamethyldiethylenetriamine, triethylenediamine, dipropylenediamine, N,N,N',N'-tetramethylpropylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, trimethylhexamethylenediamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N-dimethylcyclohexylamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dimethylaminopropylamine, diethylaminopropylamine, dibutylaminopropylamine, 1,4-diazabicyclo[2,2,2]octane(triethylenediamine), polyoxyethylenediamine, polyoxypropylenediamine, bis(2-dimethylaminoethyl)ether, dimethylaminoethoxyethoxyethanol, triethanolamine, and dimethylaminohexanol;

[0063] Alicyclic and heterocyclic amine compounds such as piperidine, piperazine, menthanediamine, isophoronediamine, methylmorpholine, ethylmorpholine, N,N',N"-tris(dimethylaminopropyl)hexahydro-s-triazine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5,5]undecane adduct, N-aminoethylpiperazine, trimethylaminoethylpiperazine, bis(4-aminocyclohexyl)methane, N,N'-dimethylpiperazine, and 1,8-diazabicyclo-[5.4.0]-undecene (DBU);

[0064] Aromatic amine compounds such as o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, benzyldimethylamine, dimethylbenzylamine, m-xylenediamine, pyridine, picoline, and α-methylbenzylmethylamine; and

[0065] Modified amine compounds such as epoxy compound-added polyamines, polyamines obtained by Michael addition, polyamines obtained by Mannich addition, thiourea-added polyamines, ketone-capped polyamines, dicyandiamide, guanidine, organic acid hydrazide, diaminomaleonitrile, amineimide, boron trifluoride-piperidine complex and boron trifluoride-monoethylamine complex.

[0066] Examples of amide compounds include dicyandiamide and polyamidoamines. Examples of polyamidoamines include polyamidoamines obtained by reacting an aliphatic dicarboxylic acid such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, or azelaic acid, or a carboxylic acid compound such as a fatty acid or a dimer acid with an aliphatic polyamine or a polyamine having a polyoxyalkylene chain.

[0067] Examples of the acid anhydride include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0068] Examples of the resin containing a phenolic hydroxyl group include polyphenol compounds such as phenol novolac resin, cresol novolac resin, aromatic hydrocarbon formaldehyde resin-modified phenolic resin, dicyclopentadienol addition resin, aralkylphenol resin (neophenol (xylok) resin), aralkylnaphthol resin, trimethylolmethane resin, tetraphenylethanol ethane resin, naphthol novolac resin, naphthol-phenol co-condensation novolac resin, naphthol-cresol co-condensation novolac resin, biphenyl-modified phenolic resin (a polyphenol compound having a phenol core linked by a dimethylene group), biphenyl-modified naphthol resin (a polyphenol compound having a phenol core linked by a dimethylene group), aminotriazine-modified phenolic resin (a polyphenol compound having a phenol core linked by melamine, benzoguanamine, etc.), and alkoxy-containing aromatic ring-modified novolac resin (a polyphenol compound in which the phenol core and the alkoxy-containing aromatic ring are linked by formaldehyde).

[0069] Examples of the phosphorus compound include alkylphosphines such as ethylphosphine and butylphosphine, primary phosphines such as phenylphosphine; dialkylphosphines such as dimethylphosphine and dipropylphosphine; secondary phosphines such as diphenylphosphine and methylethylphosphine; and tertiary phosphines such as trimethylphosphine, triethylphosphine, and triphenylphosphine.

[0070] Examples of the imidazole compound include imidazole, 1-methylimidazole, 2-methylimidazole, 3-methylimidazole, 4-methylimidazole, 5-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 3-ethylimidazole, 4-ethylimidazole, 5-ethylimidazole, 1-n-propylimidazole, 2-n-propylimidazole, 1-isopropylimidazole, 2-isopropylimidazole, 1-n-butylimidazole, 2-n-butylimidazole, 1-isobutylimidazole, 2-isobutylimidazole, 2-undecyl-1H-imidazole, 2-heptadecyl-1H-imidazole, 1,2-dimethylimidazole, 1,3-dimethylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-phenylimidazole, 2-phenyl-1H-imidazole, 4-methylimidazole. 2-Phenyl-1H-imidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-cyanoethyl-2-phenyl-4,5-bis(2-cyanoethoxy)methylimidazole, 1-dodecyl-2-methyl-3-benzylimidazole chloride, and 1-benzyl-2-phenylimidazole hydrochloride.

[0071] Examples of the imidazoline compound include 2-methylimidazoline and 2-phenylimidazoline.

[0072] Examples of the urea compound include p-chlorophenyl-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-N,N-dimethylurea, and N-(3-chloro-4-methylphenyl)-N′,N′-dimethylurea.

[0073] The curing agent may be used alone, or two or more thereof may be used in combination. Among them, dicyandiamide is preferable because a curable composition capable of forming a cured product having excellent adhesive properties can be obtained.

[0074] Examples of the curing accelerator (C2) include urea compounds, imidazole compounds, and amine compounds.

[0075] As the urea compound, the same compounds as examples of the urea compound can be used.

[0076] As the imidazole compound, the same compounds as examples of the imidazole compound can be used.

[0077] Examples of the amine compound include N,N,N',N'-tetramethylethylenediamine, pentamethyldiethylenetriamine, N,N,N',N'-tetramethylpropylenediamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N-dimethylcyclohexylamine, 1,4-diazabicyclo[2,2,2]octane(triethylenediamine), bis(2-dimethylaminoethyl) ether, dimethylaminoethoxyethoxy alcohol, triethanolamine, and dimethylaminohexanol.

[0078] The curable composition of the present invention may appropriately contain an organic solvent, an ultraviolet absorber, an antioxidant, a silicon-containing additive, a fluorine-containing additive, a flame retardant, a plasticizer, a silane coupling agent, organic beads, inorganic fine particles, an inorganic filler, a rheology control agent, a degassing agent, an antifogging agent, or a colorant. Each component can be added in any amount according to the desired performance.

[0079] In the present invention, as the use ratio of blocked isocyanate prepolymer (A) and epoxy resin (B), the mass ratio represented by (A) / (B) is preferably in the range of 5 / 95 to 40 / 60, and more preferably in the range of 10 / 90 to 30 / 70, because it is possible to obtain a curable composition capable of forming a cured product with excellent storage stability and excellent adhesion properties. As the mixing ratio of epoxy resin (B) and a curing agent (C) having a functional group capable of reacting with an epoxy group, relative to 1 mole of epoxy groups in the epoxy resin (B), the mixing ratio of the functional groups in the curing agent is preferably in the range of 0.5 to 1.1 moles. Curing accelerator (C2) can be used. When using curing accelerator (C2), relative to 100 parts by mass of epoxy resin (B), it is preferred that curing accelerator (C2) be mixed in an amount of 0.5 to 10 parts by mass.

[0080] The curable composition of the present invention may appropriately contain an organic solvent, an ultraviolet absorber, an antioxidant, a silicon-containing additive, a fluorine-containing additive, a flame retardant, a plasticizer, a silane coupling agent, organic beads, inorganic fine particles, an inorganic filler, a rheology control agent, a degassing agent, an antifogging agent, or a colorant. Each component can be added in any amount according to the desired performance.

[0081] The preparation method of the curable composition of the present invention may be a method in which the polyurethane resin, the epoxy resin (B), the curing agent (C1), and / or the curing accelerator (C2), and optional components to be contained if necessary, are uniformly mixed using a ball mill, a ball mill, a bead mill, a roller mill, a homogenizer, a super mill, a homodispersor, a multi-purpose mixer, a Banbury mixer, or a kneader.

[0082] The application of the curable composition of the present invention is not particularly limited. The curable composition can be used in various applications such as coating materials, coating agents, molding materials, insulating materials, sealants, sealants, and fiber binders. In particular, the curable composition can be suitably used as an adhesive for structural members in the fields of automobiles, electric transportation, civil engineering and construction, electronic equipment, aircraft, and aerospace industries by utilizing the characteristics of the cured product, including excellent flexibility and toughness.

[0083] For example, even when the adhesive of the present invention is used for bonding between different materials such as metal and non-metal, high bonding characteristics can be maintained without being affected by the change of temperature environment, and peeling is unlikely to occur.Except for the adhesive for structural members, the adhesive of the present invention can also be used as the adhesive for common office purposes, medical adhesive, carbon fiber adhesive or electronic material adhesive.The example of electronic material adhesive comprises the adhesive for the intermediate layer of multilayer substrate such as stacked substrate, the adhesive for the bonding of optical components, the adhesive for the bonding of optical disc, the adhesive for the installation of printed wiring board, mold bonding adhesive, the adhesive for semiconductor such as bottom filling material, and the adhesive for installing the bottom filling material, anisotropic conductive film and anisotropic conductive paste etc. such as for BGA strengthening.

[0084] Example

[0085] Hereinafter, the present invention will be specifically described by way of Examples and Comparative Examples. The present invention is not limited to the Examples listed below.

[0086] In the Examples, the weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) under the following conditions.

[0087] Measuring device: HLC-8220 manufactured by Tosoh Corporation

[0088] Column: Guard column H manufactured by Tosoh Corporation XL -H

[0089] +TSKgel G5000HXL manufactured by Tosoh Corporation

[0090] +TSKgel G4000HXL manufactured by Tosoh Corporation

[0091] +TSKgel G3000HXL manufactured by Tosoh Corporation

[0092] +TSKgel G2000HXL manufactured by Tosoh Corporation

[0093] Detector: RI (differential refractometer)

[0094] Data processing: SC-8010 manufactured by Tosoh Corporation

[0095] Measurement conditions: Column temperature: 40°C

[0096] Solvent: tetrahydrofuran

[0097] Flow rate: 1.0 mL / min

[0098] Standard: Polystyrene

[0099] Sample: A sample (100 μL) obtained by filtering a tetrahydrofuran solution having a solid content of 0.4% by mass through a microfilter

[0100] (Synthesis Example 1: Preparation of polyurethane resin (1))

[0101] In a nitrogen atmosphere, 757 parts by mass of a polyether polyol ("PTMG-2000" available from Mitsubishi Chemical Corporation, Mn: 2,000, number of functional groups: 2) was mixed at 100°C in a vacuum for 1 hour and then cooled to 60°C. When the temperature reached 60°C, 130 parts by mass of hexamethylene diisocyanate ("Desmodur H" available from Sumika Covestro Urethane Co., Ltd.) was added and mixed for 30 minutes. As a catalyst, 0.1 parts by mass of dioctyltin diacetate ("NEOSTANN U-820" available from Nitto Kasei Co., Ltd.) was added to cause a reaction at 80°C for 3 hours. Subsequently, 113 parts by mass of 4-hydroxyphenylacetonitrile (a reagent available from Sigma-Aldrich) was added as a terminal blocking agent to cause a reaction at 80°C for 5 hours. Thus, a polyurethane resin (1) was obtained.

[0102] (Synthesis Examples 2 to 18: Synthesis of Polyurethane Resins (2) to (19))

[0103] The respective components were mixed in the ratios shown in Table 1 or 2 below, and polyurethane resins (2) to (18) were obtained in the same manner as in Synthesis Example 1.

[0104] The compositions of the polyurethane resins synthesized in Synthesis Examples 1 to 19 are shown in Tables 1 and 2.

[0105] [Table 1]

[0106]

[0107] [Table 2]

[0108]

[0109] The abbreviations shown in Tables 1 and 2 mean the following.

[0110] PTMG-2000: polytetramethylene glycol ("PTMG-2000" available from Mitsubishi Chemical Corporation, Mw: 2,000, number of functional groups: 2)

[0111] PTMG-3000: polytetramethylene glycol ("PTMG-3000" available from Mitsubishi Chemical Corporation, Mw: 3,000, number of functional groups: 2)

[0112] T-700: polypropylene glycol ("T-700" available from Mitsui Chemicals & SKC Polyurethanes Inc., Mw: 700, number of functional groups: 3)

[0113] T-3000: Polypropylene glycol ("T-3000" available from Mitsui Chemicals & SKC Polyurethanes Inc., Mw: 3,000, number of functional groups: 3)

[0114] GY3500: polypropylene glycol ("GY-3500" available from JIAHUA CHEMICALS Inc., Mw: 3,500, number of functional groups: 3)

[0115] T-4000: Polypropylene glycol ("T-4000" available from Mitsui Chemicals & SKC Polyurethanes Inc., Mw: 4,000, number of functional groups: 3)

[0116] 5TP-300KB: Polyoxyethylene polyoxypropylene pentaerythritol ether ("UNILUBE 5TP-300KB" available from NOF Corporation, Mw: 4,000, number of functional groups: 4)

[0117] HDI: Hexamethylene diisocyanate ("Desmodur H" available from Sumika Covestro Urethane Co., Ltd.)

[0118] IPDI: isophorone diisocyanate ("Desmodur I" available from Sumika Covestro Urethane Co., Ltd.)

[0119] TDI: toluene diisocyanate ("T-80" available from Mitsui Chemicals & SKC Polyurethanes Inc.)

[0120] HBAN: 4-Hydroxyphenylacetonitrile (“4-Hydroxyphenylacetonitrile” available from Sigma-Aldrich) HBN: 4-Hydroxybenzonitrile (“4-Hydroxybenzonitrile” available from Tokyo Chemical Industry Co., Ltd.)

[0121] MAPN: 3-methylaminopropionitrile ("3-(methylamino)propionitrile" available from Tokyo Chemical Industry Co., Ltd.)

[0122] DABPA: diallyl bisphenol A ("DA-BPA" available from Yokkaichi Chemical Company Limited)

[0123] PTBT: 4-tert-butylphenol (available from DIC Corporation as "DIC-PTBP")

[0124] NX2024: Cardanol (available as "NX-2024" from Cardolite)

[0125] (Example 1: Preparation of curable composition (1))

[0126] 20 parts by mass of the polyurethane resin (1) obtained in Synthesis Example 1, 80 parts by mass of a bisphenol A type epoxy resin ("EPICLON 850-S" available from DIC Corporation), 5 parts by mass of dicyandiamide as a curing agent, 1 part by mass of 3,4-dichlorophenyl-N,N-dimethylurea as a curing accelerator, and 20 parts by mass of calcium carbonate as a filler were mixed to obtain a curable composition (1).

[0127] (Examples 2 to 10: Preparation of curable compositions (2) to (10))

[0128] Curable compositions (2) to (10) were obtained in the same manner as in Example 1, except that the polyurethane resins (2) to (10) obtained in Synthesis Examples 2 to 10 were used in the blending amounts shown in Table 3, respectively, instead of the polyurethane resin (1) used in Example 1.

[0129] (Comparative Examples 1 to 9: Preparation of Curable Compositions (R1) to (R9))

[0130] Curable compositions (R1) to (R9) were obtained in the same manner as in Example 1, except that the polyurethane resins (11) to (19) obtained in Synthesis Examples 11 to 19 were used in the blending amounts shown in Table 4, respectively, instead of the polyurethane resin (1) used in Example 1.

[0131] The curable compositions (1) to (10) and (R1) to (R9) obtained in Examples and Comparative Examples were used to perform the following evaluations.

[0132] [Evaluation method of adhesive properties]

[0133] Adhesive properties were evaluated based on the tensile shear test and the T-peel test.

[0134] <Production of Samples>

[0135] The curable compositions obtained in each of the examples and comparative examples were cured at 170°C for 30 minutes according to JIS K6859 (1994) (Test method for creep rupture of adhesives) and JIS K6854-3 (1999) (Test for peel adhesion strength of adhesives) to obtain specimens for tensile shear tests and T-peel tests.

[0136] <Tensile shear test>

[0137] The tensile shear strength of the specimens was measured at 25°C by the method of JIS K6859 (1994) (Test for creep rupture of adhesives) using "AUTOGRAPH AG-XPlus 100kN" manufactured by SHIMADZU CORPORATION.

[0138] <T-peel test>

[0139] The peel strength of the specimens was measured at 25°C by the method of JIS K6854-3 (1994) (Test for peel adhesion strength of adhesives) using "AUTOGRAPH AG-IS 1kN" manufactured by SHIMADZU CORPORATION.

[0140] [Evaluation method for storage stability]

[0141] The Brookfield viscosity of the curable compositions obtained in each of the examples and comparative examples was measured at 40°C by the method of measuring viscosity with a single-cylinder rotational viscometer according to JIS Z8803 (2011) (Method for measuring viscosity of liquids) using "TVB-10" manufactured by TOKI SANGYO CO., LTD. The compositions were stored at 40°C for 2 weeks, and then the viscosity was measured again by the same method. The ratio of the viscosity after storage to the viscosity of the curable composition before storage was calculated. The difference therebetween was the thickening ratio.

[0142] The compositions and evaluation results of the curable compositions (1) to (10) produced in Examples 1 to 10 and the curable compositions (R1) to (R9) produced in Comparative Examples 1 to 9 are shown in Tables 3 and 4.

[0143] [Table 3]

[0144]

[0145] [Table 4]

[0146]

[0147] The abbreviations shown in Tables 3 and 4 are meant as follows.

[0148] 850-S: Bisphenol A type epoxy resin (available as "EPICLON 850-S" from DIC Corporation)

[0149] DICY: dicyandiamide

[0150] DCMU: 3,4-dichlorophenyl-N,N-dimethylurea

[0151] In Table 4, "-" indicates that the value cannot be evaluated (cannot be measured) due to gelation.

[0152] Examples 1 to 10 shown in Table 3 are examples of curable compositions containing the polyurethane resin of the present invention. The curable compositions were confirmed to have excellent storage stability and adhesive properties.

[0153] On the other hand, Comparative Examples 1 to 8 shown in Table 4 are examples of curable compositions containing a polyurethane resin that does not contain a compound (a3) having a cyano group. The curable composition in Comparative Example 1 using DABPA was confirmed to have insufficient storage stability and adhesive properties, and the curable compositions in Comparative Examples using other blocking agents were confirmed to have insufficient adhesive properties.

Claims

1. A polyurethane resin comprising the following as a basic raw material: a polyol compound (a1); a polyisocyanate compound (a2); and A compound (a3) having a cyano group. 2 . The polyurethane resin according to claim 1 , wherein the polyol compound (a1) is a polyether polyol. 3 . The polyurethane resin according to claim 1 , wherein the compound (a3) having a cyano group further has a functional group capable of reacting with an isocyanate group. 4 . The polyurethane resin according to claim 3 , wherein the functional group capable of reacting with an isocyanate group is one or more selected from the group consisting of a phenolic hydroxyl group, an oxime group, an amino group, and an active methylene group. The polyurethane resin according to claim 1 , wherein the functional group capable of reacting with an isocyanate group is a monovalent group.

6. The polyurethane resin according to claim 3, wherein The polyurethane resin is a reaction product of a polyurethane prepolymer having an isocyanate group formed from the polyol compound (a1) and the polyisocyanate compound (a2) as base materials and the compound (a3) having a cyano group, and The functional group equivalent weight of the functional group capable of reacting with an isocyanate group in the compound (a3) is equal to or greater than the equivalent weight of the isocyanate group in the polyurethane prepolymer.

7. A curable composition comprising: The polyurethane resin according to any one of claims 1 to 6; Epoxy resin (B); and a curing agent (C1) and / or a curing accelerator (C2). 8 . The curable composition according to claim 7 , wherein the epoxy equivalent of the epoxy resin (B) is in the range of 150 to 250 g / eq. 9 . The curable composition according to claim 7 , wherein a mass ratio [(A) / (B)] of the polyurethane resin (A) to the epoxy resin (B) is in the range of 10 / 90 to 30 / 70. 10 . The curable composition according to claim 7 , wherein the curing agent (C1) contains dicyandiamide.

11. The curable composition according to claim 7, wherein the curing accelerator (C2) is one or more selected from the group consisting of urea compounds, imidazole compounds, and amine compounds.

12. A cured product of the curable composition according to claim 7. 13 . An adhesive comprising the curable composition according to claim 7 .

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