Resin composition, cured product and adhesive

Abstract

To provide a resin composition which is used as a raw material of an adhesive excellent in low temperature impact strength.SOLUTION: A resin composition is provided, including blocked urethane (A), an epoxy resin (B), a curing agent (C), and polymer fine particles (D), wherein the blocked urethane (A) includes a structural unit derived from polyol (A-1) and a structural unit derived from a polyisocyanate compound (A-2), the structural unit derived from the polyol (A-1) includes a structural unit derived from polyether polycarbonate diol represented by the following formula (1), and the epoxy resin (B) has an epoxy equivalent of 195 g / eq or more. In the formula (1), R represents a divalent hydrocarbon group having 2 to 10 carbon atoms, n is 2 to 30, and m is 1 to 20. In the formula (1), the plurality of R may be the same or different, and the plurality of n may be the same or different.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Urethane resins used in structural adhesives and resin compositions containing them have conventionally been composed of various components and have been used in a variety of applications. When an epoxy resin, known as a thermosetting resin, is contained in the resin composition, the epoxy resin is hard and brittle, and therefore, a method of adding a specific toughening agent is known as a method for improving the toughness of the epoxy resin.

[0003] For example, Patent Document 1 describes a curable resin composition containing an epoxy resin, polymer fine particles containing a rubber-containing graft copolymer, and colloidal calcium carbonate that has been surface-treated with a silane coupling agent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-164601 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the polymer fine particles described in Patent Document 1 can improve the toughness of epoxy resins, the impact strength at low temperatures is unsatisfactory. The present invention has been made in view of the above-mentioned problems of the prior art. That is, an object of the present invention is to provide a resin composition that can be used as a raw material for adhesives that have excellent low-temperature impact strength. [Means for solving the problem]

[0006] As a result of extensive research, the inventors have found that the above-mentioned problems can be solved by a resin composition containing a blocked urethane containing a specific structural unit, an epoxy resin having an epoxy equivalent weight within a specific range, a curing agent, and polymer fine particles.

[0007] That is, the gist of the present invention is as follows. [1] A resin composition comprising a blocked urethane (A), an epoxy resin (B), a curing agent (C), and polymer fine particles (D), the blocked urethane (A) contains a structural unit derived from a polyol (A-1) and a structural unit derived from a polyisocyanate compound (A-2), and the structural unit derived from the polyol (A-1) contains a structural unit derived from a polyether polycarbonate diol represented by the following formula (1): A resin composition, wherein the epoxy resin (B) contains an epoxy resin having an epoxy equivalent of 195 g / eq or more. [ka] In the above formula (1), R represents a divalent hydrocarbon group having 2 to 10 carbon atoms, n is 2 to 30, and m is 1 to 20. In addition, in formula (1), multiple R may be the same or different. (2) The resin composition according to (1), wherein the polyol (A-1) has a number average molecular weight calculated from a hydroxyl value of 600 or more and 10,000 or less. [3] The resin composition according to [1] or [2], wherein the mass ratio of the polyether polycarbonate diol represented by the formula (1) to the mass of all polyols contained in the polyol (A-1) is 50% or more. [4] The resin composition according to any one of [1] to [3], wherein each R in the formula (1) is an n-butylene group. [5] The resin composition according to any one of [1] to [4], wherein n in the formula (1) is 4 to 20. [6] The resin composition according to any one of [1] to [5], wherein the polyisocyanate compound (A-2) is a diisocyanate. [7] The resin composition according to [6], wherein the polyisocyanate compound (A-2) is an aliphatic diisocyanate or an alicyclic diisocyanate. [8] The resin composition according to any one of [1] to [7], wherein the terminal of the urethane prepolymer chain of the blocked urethane has a structure derived from a phenol compound. [9] The resin composition according to any one of [1] to [8], wherein the epoxy resin (B) contains a bisphenol-type epoxy resin.

[10] The resin composition according to any one of [1] to [9], wherein the curing agent (C) is a latent curing agent.

[11] The resin composition according to any one of [1] to

[10] , wherein the polymer fine particles (D) have a volume average particle size of 1 nm to 50 μm.

[12] The resin composition according to any one of [1] to

[11] , wherein the polymer fine particles (D) contain a rubber-containing graft copolymer.

[13] A cured product obtained by curing the resin composition according to any one of [1] to

[12] .

[14] An adhesive comprising the resin composition according to any one of [1] to

[12] . [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a resin composition that can be used as a raw material for an adhesive that has excellent low-temperature impact strength. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following description and can be modified as desired without departing from the spirit of the present invention. In this specification, when a numerical value or physical property value is enclosed by "~", the value before and after the "~" is used to include the values ​​before and after the "~" The blocked urethane of this embodiment is a heat-reactive urethane resin with blocked isocyanate groups in the urethane skeleton. The terminal active isocyanate groups are protected with a blocking agent, and the resin remains stable at room temperature. When subjected to heat treatment, the blocking agent dissociates, regenerating the active isocyanate groups, which initiate a curing and crosslinking reaction, thereby developing adhesive strength.

[0010] <Configuration of Resin Composition> A resin composition according to one embodiment of the present invention (hereinafter also simply referred to as "resin composition") is a resin composition comprising a blocked urethane (A), an epoxy resin (B), a curing agent (C), and polymer fine particles (D), the blocked urethane (A) contains a structural unit derived from a polyol (A-1) and a structural unit derived from a polyisocyanate compound (A-2), and the structural unit derived from the polyol (A-1) contains a structural unit derived from a polyether polycarbonate diol represented by the following formula (1): A resin composition, wherein the epoxy resin (B) contains an epoxy resin having an epoxy equivalent of 195 g / eq or more.

[0011] [ka]

[0012] In the above formula (1), R represents a divalent hydrocarbon group having 2 to 10 carbon atoms, n is 2 to 30, and m is 1 to 20. In formula (1), multiple Rs may be the same or different, and multiple n's may be the same or different.

[0013] [Blocked Urethane (A)] The resin composition contains a blocked urethane (A). The blocked urethane (A) contains a structural unit derived from a polyol (A-1) and a structural unit derived from a polyisocyanate compound (A-2).

[0014] (Polyol (A-1)) The blocked urethane (A) contains, as the polyol (A-1), at least a structural unit derived from the polyether polycarbonate diol represented by the above formula (1). The structural unit derived from the polyether polycarbonate diol contained as the polyol (A-1) may be of one type or two or more types.

[0015] In the above formula (1), R is a divalent hydrocarbon group having 2 to 10 carbon atoms, preferably a linear or branched alkylene group having 2 to 10 carbon atoms, more preferably a linear or branched alkylene group having 3 to 6 carbon atoms, particularly preferably a butylene group having 4 carbon atoms or a 2-methylbutylene group having 5 carbon atoms, and particularly preferably an n-butylene group. That is, from the viewpoints of industrial availability and excellent physical properties of the resulting blocked urethane, it is preferred that RO- in formula (1) is derived from polytetramethylene ether glycol.

[0016] In the above formula (1), n ​​is an average value of 2 to 30, preferably 3 to 20, more preferably 4 to 20, and even more preferably 4 to 15. If n is less than the above lower limit, the low-temperature impact strength of the resulting adhesive tends to be poor, whereas if n exceeds the above upper limit, the viscosity and crystallinity of the polyether polycarbonate diol increase, leading to poor handleability and poor storage stability of the resulting blocked urethane.

[0017] In the above formula (1), m is an average value of 1 to 20, preferably 1 to 15, and more preferably 1 to 10. If m is less than the above lower limit, the performance of the resulting blocked urethane as a reinforcing agent tends to be poor, whereas if m exceeds the above upper limit, the viscosity increases, which may impair handling during production of the blocked urethane.

[0018] The polyol (A-1) according to this embodiment may be used in combination with a polyol other than the polyether polycarbonate diol represented by formula (1) (hereinafter also referred to as "other polyols"). The structural unit derived from the other polyol may be of one type or of two or more types.

[0019] The other polyols are not particularly limited as long as they are those that are commonly used in the production of polyurethanes, and examples thereof include polyether polyols, polyester polyols, polycaprolactones, and the like. Polycarbonate polyols or polycarbonate polyols are examples of such polyols.

[0020] When other polyols are used in combination, the mass ratio of the polyether polycarbonate diol represented by formula (1) to all polyols contained in the polyol (A-1), i.e., the total mass (100%) of the polyether polycarbonate diol represented by formula (1) and other polyols, is not particularly limited, but is preferably 30% or more, more preferably 50% or more, and even more preferably 70% or more, and the upper limit is not particularly limited, and may be 100% or less. When this ratio is equal to or higher than the lower limit of the above range, the effects of storage stability and low-temperature impact strength are well balanced.

[0021] The content of structural units derived from polyol (A-1) contained in the block urethane is not particularly limited, but is preferably 44 parts by mass or more, more preferably 46 parts by mass or more, even more preferably 48 parts by mass or more, and particularly preferably 50 parts by mass or more, relative to 100 parts by mass of the block urethane. It is also preferably 85 parts by mass or less, more preferably 84 parts by mass or less, even more preferably 83 parts by mass or less, and particularly preferably 80 parts by mass or less. When the content is equal to or greater than the lower limit of the above range, the storage stability and low-temperature impact strength of the adhesive are further improved. When the content is equal to or less than the upper limit of the above range, the storage stability and low-temperature impact strength of the adhesive are further improved.

[0022] The number average molecular weight calculated from the hydroxyl value of the polyol (A-1) is not particularly limited, but is preferably 500 or more, more preferably 600 or more, even more preferably 800 or more, and particularly preferably 1000 or more, and is preferably 15000 or less, more preferably 10000 or less, even more preferably 4000 or less, and particularly preferably 3000 or less. If the number average molecular weight is at or above the lower limit of the above range, the low-temperature impact strength of the resulting adhesive is further improved. Furthermore, if the number average molecular weight is at or below the upper limit of the above range, the storage stability is excellent.

[0023] The number average molecular weight can be determined by the following method. First, the hydroxyl value of a polyol is measured in accordance with the American Society for Testing and Materials (ASTM) standard by preparing a tetrahydrofuran solution and subjecting the hydroxyl groups to urethanization with p-toluenesulfonyl isocyanate. The excess urethanization reagent is then hydrolyzed with water, and the sulfonylamide ester formed from the sample hydroxyl groups is titrated with a base to determine the hydroxyl value. Next, the number average molecular weight (Mn) is calculated from the obtained hydroxyl value using the following formula (I): Number average molecular weight = 2 × 56.1 / (hydroxyl value × 10 -3 ) ···(I) When polyol (A-1) contains multiple polyols, the number average molecular weight (Mn) of polyol (A-1) is calculated based on the mass of the average value of the multiple polyols. For example, in the case of 80 parts by mass of polyol (A-1', Mn2000) and 20 parts by mass of polyol (A-1"), Mn1000, the number average molecular weight is 2000 x 0.8 + 1000 x 0.2 = 1800.

[0024] The polyol (A-1) used as a raw material for providing the structural units derived from the polyol (A-1) may be a commercially available product.

[0025] (Polyisocyanate compound (A-2)) The blocked urethane contains structural units derived from a polyisocyanate compound (A-2). The polyisocyanate compound (A-2) may be any compound having two or more isocyanate groups, and examples thereof include various known aliphatic, alicyclic, and aromatic polyisocyanate compounds. The structural unit derived from the polyisocyanate compound (A-2) contained in the blocked urethane may be of one type or two or more types.

[0026] Examples of the polyisocyanate compound (A-2) include aliphatic diisocyanate compounds such as tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, and dimer diisocyanate in which the carboxyl groups of dimer acid are converted to isocyanate groups; 1,4-cyclohexane diisocyanate, isophorone diisocyanate, 1-methyl-2,4-cyclohexane diisocyanate, 1-methyl-2,6-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, and 1,5-pentamethylene diisocyanate. Alicyclic diisocyanate compounds include aromatic diisocyanate compounds such as xylylene diisocyanate, 4,4'-diphenyl diisocyanate, toluene diisocyanate (2,4-toluene diisocyanate, 2,6-toluene diisocyanate), m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, polymethylene polyphenyl isocyanate, phenylene diisocyanate, and m-tetramethylxylylene diisocyanate. These may be used alone or in combination of two or more.

[0027] Among these, diisocyanates are preferred because they help to suppress gelation during urethane production. Aliphatic diisocyanates and alicyclic diisocyanates are preferred because the resulting blocked urethane has favorable physical properties, and 4,4'-dicyclohexylmethane diisocyanate, 1,6-hexamethylene diisocyanate, and isophorone diisocyanate are particularly preferred because they are available industrially in large quantities at low cost.

[0028] The content of the structural unit derived from the polyisocyanate compound (A-2) contained in the block urethane is not particularly limited, but is preferably 11 parts by mass or more, more preferably 12 parts by mass or more, even more preferably 13 parts by mass or more, particularly preferably 14 parts by mass or more, and is preferably 26 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 24 parts by mass or less, particularly preferably 23 parts by mass or less, per 100 parts by mass of the block urethane. When the content is above the lower limit of the above range, the storage stability and low-temperature impact strength when used as an adhesive are further improved. When the content is below the upper limit of the above range, the storage stability and low-temperature impact strength when used as an adhesive are further improved, resulting in excellent storage stability.

[0029] As the polyisocyanate compound (A-2) as a raw material that provides the structural unit derived from the polyisocyanate compound (A-2), a commercially available product may be used.

[0030] [Blocking agent (A-3)] In the blocked urethane of this embodiment, the active isocyanate group is protected with a blocking agent (A-3), but the blocking agent (A-3) is not particularly limited. Examples of the blocking agent include monofunctional phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; bisphenols such as bisphenol A, bisphenol F, bisphenol E, bisphenol Z, bisphenol S, bisphenol AD, bisphenolacetophenone, bisphenoltrimethylcyclohexane, bisphenolfluorene, tetramethylbisphenol A, tetramethylbisphenol F, tetra-t-butylbisphenol A, and tetramethylbisphenol S; and bisphenols such as biphenol and tetramethylbisphenol. Biphenols such as phenol, dimethylbiphenol, and tetra-t-butylbiphenol; benzenediols such as hydroquinone, methylhydroquinone, dibutylhydroquinone, resorcin, and methylresorcin (here, "benzenediols" refers to compounds having one benzene ring, with two hydroxyl groups directly bonded to the benzene ring); dihydroanthrahydroquinones such as dihydroanthrahydroquinone; dihydroxydiphenyl ethers such as dihydroxydiphenyl ether; thiodiphenols such as thiodiphenol; dihydroxynaphthalenes such as dihydroxynaphthalene; dihydroxystilbenes such as dihydroxystilbene;α,α-Bis(4-hydroxyphenyl)-4-(4-hydroxy-α,α-dimethylbenzyl)-ethylbenzene, 4,4',4''-trihydroxytriphenylmethane, 4,4',4''-ethylidinetris(2-methylphenol), 4,4'-(2-hydroxybenzylidene)bis(2,3,6-trimethylphenol), 2,3,4-trihydroxydiphenylmethane, 2,4,6-tris(4-hydroxyphenyl)-1,3,5-triazine, 1,3,5-tris(4-hydroxyphenyl)- polyfunctional phenols such as 4,4'-(1-{4-[1-(4-hydroxy-3,5-dimethylphenyl)-1-methylethyl]phenyl}ethylidene)bis(2-methylphenol), 2,6-bis(4-hydroxy-3,5-dimethylbenzyl)-4-methylphenol; lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, β-propiolactam; methanol, ethanol, propyl alcohol, Aliphatic alcohols such as butyl alcohol, amyl alcohol, and lauryl alcohol; ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; alcohols such as benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate; oximes such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime; activated methylenes such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone;Mercaptans such as butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, and ethylthiophenol; acid amides such as acetanilide, acetanisidide, acetotoluide, acrylamide, methacrylamide, acetic amide, stearic acid amide, and benzamide; imides such as succinimide, phthalic acid imide, and maleic acid imide; diphenylamine, phenylnaphthylamine, Examples of suitable compounds include amine-based compounds such as xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, and butylphenylamine; imidazole-based compounds such as imidazole and 2-ethylimidazole; urea-based compounds such as urea, thiourea, ethyleneurea, ethylenethiourea, and diphenylurea; carbamate-based compounds such as N-phenylphenylcarbamate; imine-based compounds such as ethyleneimine and propyleneimine; sulfite-based compounds such as sodium bisulfite and potassium bisulfite; and azole-based compounds. Examples of the azole compounds include pyrazoles or pyrazole derivatives such as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole; imidazolidins such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole, and 2-phenylimidazole; imidazoline derivatives such as 2-methylimidazoline and 2-phenylimidazoline; and the like.

[0031] In order to obtain a blocked urethane with excellent storage stability, it is preferable that the terminal of the urethane prepolymer chain of the blocked urethane has a structure derived from a phenol compound, and therefore, among the blocking agents (A-3), it is preferable to use monofunctional phenol-based or polyfunctional phenol-based blocking agents. Note that commercially available blocking agents can be used as the blocking agent (A-3).

[0032] The content of structural units derived from the blocking agent (A-3) contained in the block urethane is not particularly limited, but is preferably 3 parts by mass or more, more preferably 4 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 6 parts by mass or more, relative to 100 parts by mass of the block urethane. It is also preferably 29 parts by mass or less, more preferably 27 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 23 parts by mass or less. When the content is equal to or greater than the lower limit of the above range, the storage stability and low-temperature impact strength of the adhesive are further improved. When the content is equal to or less than the upper limit of the above range, the storage stability and low-temperature impact strength of the adhesive are further improved.

[0033] The structure of the blocked urethane can be analyzed by NMR or the like. The content of structural units derived from the blocking agent (A-3) contained in the block urethane can be evaluated by the above-mentioned analytical method, but it may also be evaluated from the amount of each raw material used.

[0034] [Method for producing blocked urethane (A)] The method for producing the blocked urethane (A) according to this embodiment is not particularly limited as long as it is a commonly used method, but for example, it can be produced by going through a step of reacting a polyol (A-1) with a polyisocyanate compound (A-2) to obtain a urethane prepolymer (hereinafter referred to as a prepolymerization step), and a step of blocking the terminal isocyanate groups of the urethane prepolymer with a blocking agent (hereinafter referred to as a blocking step). In this example, at least a polyether polycarbonate diol represented by formula (1) is used as the polyol (A-1).

[0035] (Prepolymerization process) In the prepolymerization step, polyol (A-1) is reacted with an excess equivalent of polyisocyanate compound (A-2) relative to the hydroxyl group equivalent of polyol (A-1) to produce a prepolymer having an isocyanate group at the molecular chain terminal. The molar ratio of the isocyanate groups of the polyisocyanate compound (A-2) to the hydroxyl groups derived from the polyol (A-1) in the prepolymerization step (isocyanate groups of the polyisocyanate compound (A-2) / hydroxyl groups derived from the polyol (A-1)) is preferably 1.2 to 5.0, more preferably 1.4 to 3.0, and particularly preferably 1.6 to 2.5. By keeping it within the above range, a decrease in the number of functional groups as a blocked urethane and an increase in the amount of unreacted polyisocyanate monomer remaining in the prepolymerization step can be suppressed, allowing the performance as a toughening agent to be fully exhibited. The polyol (A-1) used may be one type, or, as mentioned above, two types.

[0036] In the prepolymerization step, a catalyst may be added as needed. Examples of the catalyst include amine catalysts such as triethylamine, tributylamine, N-ethylmorpholine, and triethylenediamine, acid catalysts such as acetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, and sulfonic acid, tin compounds such as trimethyltin laurate, dibutyltin dilaurate, dioctyltin dilaurate, and dioctyltin dineodecanoate, and organic catalysts such as titanium compounds. Known catalysts such as metal salts can be used, and one catalyst may be used alone, or two or more catalysts may be used in combination. The amount of the catalyst added is preferably 1 ppm or more and 3000 ppm or less with respect to 100 parts by mass of the total amount of the polyurethane resin.

[0037] The reaction temperature in the prepolymerization reaction is not particularly limited, but from the viewpoint of controlling heat generation during the reaction, it is preferably 60 to 100°C, more preferably 65 to 95°C, and even more preferably 70 to 90°C. The reaction time in the prepolymerization reaction is not particularly limited, but from the viewpoint of disappearance of isocyanate groups, it is preferably 30 to 210 minutes, more preferably 60 to 180 minutes, and even more preferably 90 to 150 minutes. The reaction atmosphere in the prepolymerization reaction is not particularly limited, and may be an air atmosphere, but is preferably an inert gas atmosphere such as nitrogen gas or argon gas.

[0038] (Blocking process) In the blocking step, the terminal isocyanate groups of the prepolymer having isocyanate groups at the molecular chain terminals produced in the prepolymerization step are blocked with a blocking agent to produce a blocked urethane. The molar ratio of the blocking agent to the terminal isocyanate groups of the prepolymer in the blocking step (blocking agent / terminal isocyanate groups of the prepolymer) is preferably 1.0 to 5.0, more preferably 1.1 to 3.0, and particularly preferably 1.2 to 2.0. If the ratio is less than the lower limit, the isocyanate groups of the prepolymer will remain, shortening the storage stability of the blocked urethane and the pot life of the curable composition. If the ratio exceeds the upper limit, the amount of remaining monomer of the blocking agent will increase, impairing the adhesiveness when used as an adhesive, which is undesirable.

[0039] In the blocking step, a catalyst can be added as needed. Examples of the catalyst that can be used include amine catalysts such as triethylamine, tributylamine, N-ethylmorpholine, and triethylenediamine; acid catalysts such as acetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, and sulfonic acid; tin compounds such as trimethyltin laurate, dibutyltin dilaurate, dioctyltin dilaurate, and dioctyltin dineodecanoate; and organometallic salts of titanium compounds. The catalyst may be used alone or in combination of two or more. The catalyst used may be the same as or different from that used in the prepolymerization step. The amount of the catalyst added is preferably 1 ppm or more and 3000 ppm or less with respect to 100 parts by mass of the total amount of the polyurethane resin.

[0040] The reaction temperature in the blocking reaction is not particularly limited, but from the viewpoint of controlling heat generation during the reaction, it is preferably 70 to 110°C, more preferably 75 to 105°C, and even more preferably 80 to 100°C. The reaction time in the blocking reaction is not particularly limited, but from the viewpoint of disappearance of isocyanate groups, it is preferably 1 to 20 hours, more preferably 2 to 18 hours, and even more preferably 3 to 16 hours. The reaction atmosphere in the blocking reaction is not particularly limited, and may be an air atmosphere, but is preferably an inert gas atmosphere such as nitrogen gas or argon gas.

[0041] [Epoxy resin (B)] The epoxy resin (B) used in the resin composition according to this embodiment contains an epoxy resin having an epoxy equivalent of 195 g / eq or more, from the viewpoint that the resulting cured product has excellent impact resistance. From the same viewpoint, the epoxy equivalent of the epoxy resin contained in the epoxy resin (B) is preferably 205 g / eq or more, more preferably 215 g / eq or more, and even more preferably 230 g / eq or more. In addition, from the viewpoint of the handleability of the resin composition, Therefore, it is preferably 2000 g / eq or less, more preferably 1300 g / eq or less, and even more preferably 1000 g / eq or less.

[0042] The mass ratio of the epoxy resin having an epoxy equivalent of 195 g / eq or more to the mass of all epoxy resins contained in the resin composition is not particularly limited, but is preferably 2% or more, more preferably 5% or more, and even more preferably 8% or more, and is preferably 33% or less, more preferably 29% or less, and even more preferably 25% or less. If the ratio is within the above range, the adhesive will have an excellent balance of heat resistance and low-temperature impact strength.

[0043] In addition, from the viewpoint of the handleability of the resulting resin composition, it is preferable that the epoxy resin (B) further contains an epoxy resin having an epoxy equivalent of less than 195 g / eq. The mass ratio of epoxy resins having an epoxy equivalent weight of less than 195 g / eq to the mass of all epoxy resins contained in the resin composition is not particularly limited, but is preferably 67% or more, more preferably 71% or more, and even more preferably 75% or more, and is preferably 98% or less, more preferably 95% or less, and even more preferably 92% or less. If the ratio is within the above range, the adhesive will have an excellent balance of heat resistance and low-temperature impact strength.

[0044] The epoxy equivalent (g / eq) of the epoxy resin is measured according to JIS K 7236.

[0045] The epoxy resin (B) is not particularly limited as long as it has difunctional or higher epoxy groups and satisfies the epoxy equivalent requirement, and examples thereof include glycidyl ether epoxy resins such as bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, biphenyl epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, bisphenol A novolac epoxy resins, tetrabromobisphenol A epoxy resins, and other polyfunctional phenol epoxy resins, epoxy resins in which the aromatic rings of the above aromatic epoxy resins have been hydrogenated, glycidyl ester epoxy resins, glycidyl amine epoxy resins, linear aliphatic epoxy resins, alicyclic epoxy resins, and heterocyclic epoxy resins. Among these, from the viewpoint of the handleability of the resulting resin composition, it is preferable that the epoxy resin (B) contains a bisphenol epoxy resin, and from the viewpoint of industrial availability, bisphenol A epoxy resins and bisphenol F epoxy resins are particularly preferred. The other epoxy resins listed above may be used alone or in combination of two or more. In addition to the epoxy resin, a reactive diluent may also be used.

[0046] The amount of the blocked urethane blended relative to the epoxy resin component in the resin composition is preferably 5 to 80 parts by mass, more preferably 10 to 75 parts by mass, and particularly preferably 20 to 70 parts by mass, when the total mass of the epoxy resin component and the blocked urethane is 100 parts by mass. By blending the blocked urethane in this range, the effect of the blocked urethane as a reinforcing agent can be improved and the elasticity inherent in the epoxy resin can be maintained.

[0047] [Hardening agent (C)] The curing agent (C) used in the resin composition according to this embodiment is a substance that contributes to the crosslinking reaction and / or chain extension reaction between epoxy groups in the epoxy resin. In this disclosure, even substances that are usually called "curing accelerators" are considered to be curing agents as long as they contribute to the crosslinking reaction and / or chain extension reaction between epoxy groups in the epoxy resin.

[0048] The content of the curing agent in the resin composition according to this embodiment is 100 mass % of the epoxy resin component. The content is preferably 0.1 to 1000 parts by mass, more preferably 100 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 60 parts by mass or less, relative to the total mass of the polymer. The preferred amounts of the curing agent are described below depending on the type of curing agent.

[0049] The curing agent (C) used in the resin composition according to this embodiment is preferably a latent curing agent. In this embodiment, the term "latent" refers to a property in which the curing agent does not act as a curing agent at room temperature and normal pressure, but acts as a curing agent when heated. In the resin composition according to the present embodiment, it is preferable to use, as the curing agent, at least one selected from the group consisting of polyfunctional phenols, polyisocyanate compounds, amine compounds, acid anhydride compounds, imidazole compounds, urea compounds, amide compounds, cationic polymerization initiators, organic phosphines, phosphonium salts, and tetraphenylboron salts. Examples of polyfunctional phenols include bisphenols such as bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol AD, bisphenol Z, and tetrabromobisphenol A; biphenols such as 4,4'-biphenol and 3,3',5,5'-tetramethyl-4,4'-biphenol; catechol, resorcinol, hydroquinone, and dihydroxynaphthalenes; and compounds in which the hydrogen atoms bonded to the aromatic rings of these compounds have been substituted with non-interfering substituents such as halogen groups, alkyl groups, aryl groups, ether groups, ester groups, and organic substituents containing heteroelements such as sulfur, phosphorus, and silicon.

[0050] Further examples include novolaks and resols, which are polycondensates of these phenols, or monofunctional phenols such as phenol, cresol, and alkylphenols with aldehydes. Examples of polyisocyanate compounds include tolylene diisocyanate, methylcyclohexane diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, dimer acid diisocyanate, trimethylhexamethylene diisocyanate, lysine triisocyanate, etc. Further examples include polyisocyanate compounds obtained by reacting these polyisocyanate compounds with compounds having at least two active hydrogen atoms such as amino groups, hydroxyl groups, carboxyl groups, and water, as well as trimers to pentamers of the above polyisocyanate compounds.

[0051] Examples of amine compounds include aliphatic primary, secondary, and tertiary amines, aromatic primary, secondary, and tertiary amines, cyclic amines, guanidines, and urea derivatives. Specific examples include triethylenetetramine, diaminodiphenylmethane, diaminodiphenyl ether, metaxylenediamine, dicyandiamide, 1,8-diazabicyclo(5,4,0)-7-undecene, 1,5-diazabicyclo(4,3,0)-5-nonene, dimethylurea, and guanylurea.

[0052] Examples of the acid anhydride compound include phthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, and condensates of maleic anhydride and unsaturated compounds. Examples of imidazole compounds include 1-isobutyl-2-methylimidazole, 2-methylimidazole, 1-benzyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, benzimidazole, etc. Although imidazole compounds also function as curing accelerators, which will be described later, they are classified as curing agents in the present disclosure.

[0053] Examples of the urea compound include p-chlorophenyl-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea, and 3-(3,4-dichlorophenyl)-N,N-dimethylurea. , N-(3-chloro-4-methylphenyl)-N',N'-dimethylurea, etc. Although urea compounds also function as curing accelerators, which will be described later, they are classified as curing agents in the present disclosure.

[0054] Examples of the amide-based compound include dicyandiamide and its derivatives, polyamide resins, and the like. The cationic polymerization initiator generates cations when exposed to heat or active energy rays, and examples thereof include aromatic onium salts. - , BF4 - , AsF6 - , PF6 - , CF3SO3 2- , B(C6F5)4 - and an aromatic cation component containing an atom such as iodine, sulfur, nitrogen, phosphorus, etc. Diaryliodonium salts and triarylsulfonium salts are particularly preferred.

[0055] Examples of organic phosphines include tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, and phenylphosphine. Examples of phosphonium salts include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate, and tetrabutylphosphonium tetrabutylborate. Examples of tetraphenylboron salts include 2-ethyl-4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate.

[0056] When a polyfunctional phenol, an amine compound, or an acid anhydride compound is used as the curing agent, it is preferable to use them so that the equivalent ratio of the number of functional groups in the curing agent (the number of hydroxyl groups in the polyfunctional phenol, the number of amino groups in the amine compound, or the number of acid anhydride groups in the acid anhydride compound) to the total number of epoxy groups in the curable composition is in the range of 1:0.8 to 1:1.5. When a polyisocyanate compound is used as the curing agent, it is preferable to use it so that the equivalent ratio of the number of isocyanate groups in the polyisocyanate compound to the number of hydroxyl groups in the curable composition is in the range of 1:0.01 to 1:1.5.

[0057] When an imidazole compound is used as a curing agent, it is preferably used in an amount of 0.5 to 10 parts by mass per 100 parts by mass of the epoxy resin component. When an amide compound is used as the curing agent, it is preferably used in an amount of 0.1 to 20% by mass based on the total amount of the epoxy resin component and the amide compound. When a cationic polymerization initiator is used as a curing agent, it is preferably used in an amount of 0.01 to 15 parts by mass per 100 parts by mass of the epoxy resin component. When organic phosphines, phosphonium salts or tetraphenylboron salts are used as the curing agent, it is preferable to use them in an amount of 0.1 to 20 mass % based on the total amount of the epoxy resin component and the organic phosphines, phosphonium salts or tetraphenylboron salts.

[0058] In addition to the curing agents listed above, for example, mercaptan compounds, organic acid dihydrazides, boron halide amine complexes, and the like can also be used as curing agents in the curable composition according to this embodiment. These curing agents may be used alone or in combination of two or more. As the curing agent, dicyandiamide is preferred from the viewpoint of ensuring the pot life of the curable composition.

[0059] [Polymer particles (D)] The resin composition according to this embodiment preferably further contains polymer fine particles (D). By using the blocked urethane and polymer fine particles (D) in combination as a reinforcing agent in an epoxy resin, the low-temperature impact strength of the resulting adhesive is further improved.

[0060] The volume average particle diameter (Mv) of the polymer fine particles (D) is preferably 1 nm to 50 μm, and in consideration of industrial productivity, more preferably 5 nm to 10 μm, even more preferably 10 nm to 1 μm, and particularly preferably 50 nm to 500 nm. By setting the volume average particle diameter of the polymer fine particles within this range, there is an advantage that the toughness-improving effect is improved and a highly stable resin composition can be obtained.

[0061] In this specification, the "volume average particle diameter (Mv) of polymer fine particles (D)" refers to the volume average particle diameter of primary particles of polymer fine particles (D), unless otherwise specified. The volume average particle diameter (Mv) of polymer fine particles (D) can be measured using a dynamic light scattering particle size distribution analyzer (e.g., Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.)) using an aqueous latex containing polymer fine particles (D) as a sample. Alternatively, the volume average particle diameter of polymer fine particles (D) can be measured by cutting a cured product of the curable resin composition, photographing the cut surface using an electron microscope or the like, and using the obtained photographed data (photographed image).

[0062] The polymer fine particles (D) are preferably dispersed, but may not be dispersed.

[0063] From the viewpoint of a balance between the ease of handling of the resulting resin composition and the effect of improving low-temperature impact strength, the content of the polymer fine particles (D) is preferably 1 to 80 parts by mass, more preferably 5 to 50 parts by mass, and particularly preferably 10 to 40 parts by mass, per 100 parts by mass of the epoxy resin.

[0064] The polymer particles (D) according to this embodiment preferably contain a rubber-containing graft copolymer, which has an elastomer and a graft portion graft-bonded to the elastomer.

[0065] For details of the elastomer, graft portion, etc. related to the rubber-containing graft copolymer according to this embodiment, the contents described in JP 2020-164601 A can be cited.

[0066] The rubber-containing graft copolymer may be a commercially available product, for example, Kane Ace MX-154 (manufactured by Kaneka Corporation).

[0067] The rubber-containing graft copolymers may be used alone or in combination of two or more kinds.

[0068] The polymer fine particles (D) according to this embodiment may be a combination of a rubber-containing graft copolymer and a polymer fine particle other than a rubber-containing graft copolymer. When a rubber-containing graft copolymer is used in combination with polymer microparticles other than the rubber-containing graft copolymer, the total mass proportion of the rubber-containing graft copolymer in the entire polymer microparticles according to this embodiment is preferably 10% or more, and more preferably 30% or more.

[0069] [Modifier] The resin composition according to this embodiment may contain a modifier other than the blocked urethane according to this embodiment in order to improve the adhesiveness and toughness when used as an adhesive. Examples of modifiers include rubber-modified epoxy resins, urethane-modified epoxy resins, and rubber particles. When using these modifiers, they may be used alone or in combination of two or more. Examples of rubber-modified epoxy resins and urethane-modified epoxy resins are shown below.

[0070] (rubber-modified epoxy resin) Rubber-modified epoxy resins are reaction products obtained by reacting rubber with an epoxy group-containing compound, and have an average of 1.1 or more, preferably 2 or more, epoxy groups per molecule. Examples of rubbers include polybutadiene, acrylonitrile butadiene rubber (NBR), and carboxyl-terminated NBR (CTBN). From the viewpoint of the toughness-improving effect of the resulting resin composition, the rubber-modified epoxy resin is preferably a carboxy-terminated butadiene-nitrile copolymer epoxy resin or an acrylonitrile-butadiene copolymer-modified epoxy resin. The rubber-modified epoxy resins may be used either alone or in combination of two or more.

[0071] There are no particular limitations on the production of rubber-modified epoxy resins. For example, they can be produced by reacting rubber with epoxy in a large amount of epoxy. There are no particular limitations on the epoxy (e.g., epoxy resin) used in producing the rubber-modified epoxy resin. For example, conventionally known epoxy resins can be used. As the rubber-modified epoxy resin, commercially available products may be used.

[0072] (urethane-modified epoxy resin) The urethane-modified epoxy resin is a reaction product obtained by reacting a compound containing an epoxy group and a group reactive with an isocyanate group with a urethane prepolymer containing an isocyanate group, and has an average of 1.1 or more epoxy groups per molecule, preferably 2 or more. For example, a urethane-modified epoxy resin can be obtained by reacting a hydroxyl-containing epoxy compound with a urethane prepolymer. The urethane-modified epoxy resins can be used either alone or in combination of two or more.

[0073] There are no particular limitations on the production of urethane-modified epoxy resins. For example, they can be produced by reacting urethane with epoxy in a large amount of epoxy (e.g., epoxy resin). There are no particular limitations on the epoxy used in producing the urethane-modified epoxy resin. For example, conventionally known epoxy resins can be used. As the urethane-modified epoxy resin, commercially available products may be used.

[0074] When the resin composition according to the present embodiment contains a modifier, the amount of modifier blended is preferably 5 to 80 parts by mass, more preferably 10 to 70 parts by mass, and particularly preferably 20 to 50 parts by mass, per 100 parts by mass of the epoxy resin. By blending the amount of modifier within the above range, the toughness-improving effect of the resin composition can be improved and the elasticity inherent in the epoxy resin can be maintained.

[0075] [Other ingredients] The resin composition according to the present embodiment may contain other components in addition to the components listed above. Examples of other components include curing accelerators (which may be the curing agents described above), coupling agents, flame retardants, antioxidants, light stabilizers, plasticizers, reactive diluents, pigments, inorganic fillers, and organic fillers (excluding those that fall under the modifiers described above). The other components listed above can be used in appropriate combinations depending on the desired physical properties of the epoxy resin-containing composition.

[0076] <Cured product> A cured product according to another embodiment of the present invention is a cured product obtained by curing the above-described resin composition. The method for curing the resin composition is not particularly limited, and can be performed by a known method. The curing conditions can be appropriately set depending on the components contained in the resin composition.

[0077] <Application> The resin composition of this embodiment has high peel strength, and the cured product obtained by curing the resin composition of this embodiment also has high adhesive strength and is highly reliable. Therefore, the resin composition of this embodiment and its cured product can be effectively used in any application requiring these physical properties. For example, it can be suitably used in applications in the coating field, such as electrodeposition coatings for automobiles, heavy-duty corrosion-resistant coatings for ships and bridges, and coatings for the interior of beverage cans; in the electrical and electronic fields, such as laminates, semiconductor encapsulants, insulating powder coatings, and coil impregnation; and in the civil engineering, construction, and adhesive fields, such as earthquake reinforcement for bridges, concrete reinforcement, building flooring, water facility linings, drainage and permeable pavements, and adhesives for vehicles and aircraft. Among these, it is particularly useful for adhesive applications. Furthermore, when the resin composition and its cured product are used for these applications, there are no particular limitations on the manner of use. For example, the resin composition or its cured product can be incorporated into adhesives or the like. [Example]

[0078] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Note that the values ​​of various production conditions and evaluation results in the following examples represent preferred upper or lower limit values ​​in the embodiments of the present invention, and a preferred range may be defined by a combination of the above-mentioned upper or lower limit values ​​and the values ​​in the following examples or values ​​between the examples.

[0079] <Raw materials, etc.> The raw materials used in the following examples and comparative examples are as follows.

[0080] [Polyol (A-1)] A-1a: Polyether polycarbonate diol (PEPCD NT2006 (constituent monomer PTMG650 (n = 9) number average molecular weight 2000) manufactured by Mitsubishi Chemical Corporation) A-1b: Polyether polycarbonate diol (constituent monomer PTMG1000 (n = 14) number average molecular weight 2100)

[0081] (Number average molecular weight of polyol) The hydroxyl value of the polyol was determined in accordance with the American Society for Testing and Materials (ASTM) standard by preparing a tetrahydrofuran solution containing p-toluenesulfonyl isocyanate to convert the hydroxyl groups to urethan. The excess urethanizing reagent was then hydrolyzed with water, and the sulfonylamide ester formed from the sample hydroxyl groups was titrated with a base. The number average molecular weight (Mn) was calculated from the obtained hydroxyl value according to the following formula (I). Number average molecular weight = 2 × 56.1 / (hydroxyl value × 10 -3 ) …(I)

[0082] [Polyisocyanate compound (A-2)] A-2: Isophorone diisocyanate (Tokyo Chemical Industry Co., Ltd.)

[0083] [Blocking agent (A-3)] A-3: p-t-butylphenol (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0084] [Epoxy resin (B)] B-1: Bisphenol A liquid epoxy resin (Mitsubishi Chemical Corporation jER828 epoxy equivalent 186g / eq) B-2: Bisphenol A solid epoxy resin (Mitsubishi Chemical Corporation jER1003F, epoxy equivalent 750g / eq)

[0085] [Hardening agent (C)] C-1: Dicyandiamide (DICY7 manufactured by Mitsubishi Chemical Corporation)

[0086] [Polymer particles (D)] D-1: Kane Ace MX-154 (manufactured by Kaneka Corporation, volume average particle diameter 220 nm, polymer particles dispersed at 40% by mass in bisphenol A epoxy resin that is liquid at room temperature)

[0087] [Curing accelerator] DCMU: 3-(3,4-dichlorophenyl)-1,1-dimethylurea (Tokyo Chemical Industry Co., Ltd.)

[0088] [Glass beads] J-60: Glass beads with a particle size of approximately 250 μm (Potters Barotini Co., Ltd.)

[0089] <Characteristics evaluation> The evaluation methods in the following examples and comparative examples are as follows.

[0090] [Wedge impact test JIS K6865] The resin compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were applied to a 0.8 mm thick bent steel plate (JIS G3141, SPCC-SD, Engineering Test Services) coated with rust-preventive oil (P-5960, Nippon Kogyo Oil Co., Ltd.). The bent steel plate coated with rust-preventive oil was then bonded to the coated steel plate and cured by heating at 170°C for 20 minutes. After curing, any excess cured material was removed from the steel plate to obtain symmetrical wedge test specimens. Using a Hydroshot HITS-T10 high-speed tensile tester (Shimadzu Corporation, 10 kN load cell), symmetrical wedge test specimens were driven into the test piece at -40°C and 2 m / s, and the dynamic cleavage resistance was measured during the cleavage of a 20 mm wide, 30 mm long cured epoxy resin specimen. The average dynamic cleavage resistance values ​​for the first 25% and last 10% of the travel distance were used to determine the low-temperature impact strength. Higher low-temperature impact strength indicates better performance.

[0091] [Production of Polyol (A-1b)] A 1 L four-neck glass flask equipped with a magnetic stirrer, a distillate trap, a pressure regulator, and a 400 mm Vigreux tube was charged with 660.44 parts by mass of polytetramethylene ether glycol (PTMG1000 (number average molecular weight 1000) manufactured by Mitsubishi Chemical Corporation), 145.64 parts by mass of ethylene carbonate (manufactured by Mitsubishi Chemical Corporation), and 0.2938 g of magnesium acetylacetonate (manufactured by Tokyo Chemical Industry Co., Ltd.), and the atmosphere in the flask was purged with nitrogen gas. With stirring, the reaction solution was heated to 150°C, the pressure was reduced to 6-4 kPa, and the reaction was carried out for 7 hours while ethylene glycol and ethylene carbonate were removed from the system. Then, 1.29 parts by mass of a 0.84% ​​by mass solution of phosphoric acid (Tokyo Chemical Industry Co., Ltd.) / 1,4-butanediol (Mitsubishi Chemical Corporation) was added to the reaction mixture in the flask to deactivate the catalyst. The Vigreux tube was then removed, and residual monomers were removed by blowing in nitrogen at 0.8 kPa or less and a reaction temperature of 160-180°C. After removing the residual monomers, a polyether polycarbonate diol with a hydroxyl value of 53.31 mgKOH / g was obtained.

[0092] [Blocked urethane manufacturing] (Production Example 1) 94 parts by mass of polyether polycarbonate diol (PEPCD NT2006 manufactured by Mitsubishi Chemical Corporation) (A-1a) and 22 parts by mass of isophorone diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) (A-2) were placed in a 0.5 L flask and heated to 60°C under a nitrogen gas atmosphere. Next, Neostan U-830 (hereinafter referred to as "U-830") was added as a urethanization catalyst. This may occur. 0.0072 parts by mass of (manufactured by Nitto Kasei Co., Ltd.) (100 ppm by mass relative to the polyether polycarbonate diol) was added to a separable flask, and after the heat generation subsided, the temperature was raised to 80°C and stirred for approximately two hours. The concentration of isocyanate groups was analyzed, and it was confirmed that the theoretical amount of isocyanate groups had been consumed. Next, 15 parts by mass of pt-butylphenol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (A-3) was added to the separable flask, and the temperature was raised to 90°C. After this, the reaction was continued with stirring until the peaks due to isocyanate groups disappeared in the IR spectrum, yielding blocked urethane No. (1).

[0093] (Production Example 2) A blocked urethane was produced in the same manner as in Production Example 1, except that the polyol (A-1), polyisocyanate compound (A-2), and blocking agent (A-3) were changed to the raw materials and parts by mass shown in Table 1, thereby obtaining blocked urethane No. (2).

[0094] [Table 1]

[0095] Example 1 A resin composition was obtained by mixing 2 parts by mass of the blocked urethane No. (1) produced in Production Example 1, 2.5 parts by mass of epoxy resin (B-1), 0.5 parts by mass of epoxy resin (B-2), 0.58 parts by mass of curing agent (C-1), 5 parts by mass of polymer fine particles (D-1) as the (D) component (2 parts polymer fine particles, 3 parts bisphenol A type epoxy resin), 0.14 parts by mass of DCMU as a curing accelerator, and 0.05 parts by mass of glass beads J-60 with a particle size of approximately 250 μm as a spacer.

[0096] (Examples 2 to 3, Comparative Examples 1 to 3) A resin composition was obtained in the same manner as in Example 1, except that the blocked urethane (A), epoxy resin (B), curing agent (C), polymer fine particles (D), curing accelerator, and glass beads were changed to the raw materials and parts by mass shown in Table 2.

[0097] The resin compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to impact strength evaluation by the wedge impact test as described above. The results are shown in Table 2.

[0098] [Table 2]

[0099] <Evaluation results> As can be seen from the above, the low-temperature impact strength of an epoxy resin can be improved by using a blocked urethane containing a specific structural unit, an epoxy resin having an epoxy equivalent weight in a specific range, and polymer fine particles. [Industrial Applicability]

[0100] According to the resin composition of the present invention, the low-temperature impact strength of the epoxy resin can be improved by using a blocked urethane containing a specific structural unit, an epoxy resin having an epoxy equivalent within a specific range, and polymer fine particles, and therefore the resin composition can be suitably used as an adhesive.

Claims

1. A resin composition comprising a blocked urethane (A), an epoxy resin (B), a curing agent (C), and polymer fine particles (D), the blocked urethane (A) contains a structural unit derived from a polyol (A-1) and a structural unit derived from a polyisocyanate compound (A-2), and the structural unit derived from the polyol (A-1) contains a structural unit derived from a polyether polycarbonate diol represented by the following formula (1): A resin composition comprising the epoxy resin (B) having an epoxy equivalent of 195 g / eq or more. 【Chemical 1】 (In the above formula (1), R represents a divalent hydrocarbon group having 2 to 10 carbon atoms, n is 2 to 30, and m is 1 to 20. In addition, in formula (1), multiple Rs may be the same or different, and multiple ns may be the same or different.)

2. The resin composition according to claim 1, wherein the polyol (A-1) has a number average molecular weight calculated from a hydroxyl value of 600 or more and 10,000 or less.

3. The resin composition according to claim 1, wherein the mass ratio of the polyether polycarbonate diol represented by the formula (1) to the mass of all polyols contained in the polyol (A-1) is 50% or more.

4. The resin composition according to claim 1, wherein each R in the formula (1) is an n-butylene group.

5. The resin composition according to claim 1, wherein n in the formula (1) is 4 to 20.

6. The resin composition according to claim 1, wherein the polyisocyanate compound (A-2) is a diisocyanate.

7. The resin composition according to claim 6, wherein the polyisocyanate compound (A-2) is an aliphatic diisocyanate or an alicyclic diisocyanate.

8. 2. The resin composition according to claim 1, wherein the terminal of the urethane prepolymer chain of the blocked urethane has a structure derived from a phenol compound.

9. The resin composition according to claim 1 , wherein the epoxy resin (B) comprises a bisphenol-type epoxy resin.

10. The resin composition according to claim 1 , wherein the curing agent (C) is a latent curing agent.

11. 2. The resin composition according to claim 1, wherein the polymer fine particles (D) have a volume average particle diameter of 1 nm to 50 μm.

12. 2. The resin of claim 1, wherein the polymeric fine particles (D) comprise a rubber-containing graft copolymer. composition.

13. A cured product obtained by curing the resin composition according to any one of claims 1 to 12.

14. An adhesive comprising the resin composition according to any one of claims 1 to 12.

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