JP7203577B2 - Curable resin composition - Google Patents

Description

The present invention relates to a curable resin composition, and more specifically, it comprises an epoxy resin, a polyurethane structure-containing compound and a latent curing agent, and contains a specific amount of dicyclopentadiene type epoxy resin as the epoxy resin. It is characterized by being excellent in flexibility because it contains a compound having a urethane structure, and is particularly excellent in adhesion to aluminum substrates, so that it can be suitably used as a structural adhesive. It is.

Structural adhesives are widely used as bonding agents for metal members in a wide range of fields such as automobiles, ships, aviation, space, civil engineering, and construction. As a structural adhesive, a thermosetting structural adhesive obtained by modifying an epoxy resin base with an elastomer or the like is widely used.

In order to use it as a structural adhesive, it is a matter of course that it must have excellent adhesion to various substrates, but flexibility is also required in order to maintain adhesion. . For example, when existing structural adhesives are used at low temperatures, their adhesiveness decreases due to their reduced flexibility. It is not suitable for the intended use.

Patent Document 1 proposes a curable epoxy-blocked urethane composition obtained from an epoxy resin, a blocked isocyanate compound and a latent curing agent. Patent Document 2 proposes a bisphenol-type epoxy resin and a blocked isocyanate. An epoxy resin composition suitable for a structural adhesive has been proposed, which comprises a urethane-modified epoxy resin, a carboxyl group-containing butadiene-acrylonitrile liquid rubber, and a curing agent. Epoxy resin-based adhesive compositions containing 10% by weight or more of the total epoxy resin have been proposed. be.

On the other hand, Patent Document 4 and the like propose to mix a dicyclopentadiene type epoxy resin in a one-part curing resin composition, but it is described that it is combined with a urethane material and that a specific amount is used. It has not been.

JP-A-5-155973 JP-A-5-148337 JP-A-7-41750 JP 2015-221866 A

An object of the present invention is to provide a curable resin composition that has excellent flexibility in a wide temperature range from low to high temperatures, has excellent adhesion to aluminum substrates in particular, and is suitable as a structural adhesive. to provide.

As a result of extensive studies, the present inventors have found a curable resin composition containing an epoxy resin, a urethane-modified epoxy resin or block urethane, and a latent curing agent, wherein the epoxy resin is a dicyclopentadiene type epoxy The inventors have found that a curable resin composition containing a resin can be obtained which has particularly excellent adhesion to an aluminum substrate, and have arrived at the present invention.

That is, the present invention contains (A) an epoxy resin, (B) a compound having a urethane structure, and (C) a latent curing agent,
(A) the epoxy resin contains a dicyclopentadiene type epoxy resin,
The present invention provides a curable resin composition in which the content of the dicyclopentadiene type epoxy resin is 0.5 to 30 parts by mass per 100 parts by mass of components (A) and (B) combined.

ADVANTAGE OF THE INVENTION According to this invention, the curable resin composition which is excellent in adhesiveness with an aluminum base material and has flexibility in a wide temperature range from low temperature to high temperature can be obtained. The curable resin composition can be suitably used as a structural adhesive, particularly as an automotive structural adhesive.

The curable resin composition of the present invention is described in detail below.

The curable resin composition of the present invention contains (A) an epoxy resin. (A) The epoxy resin contains a dicyclopentadiene type epoxy resin.
As the dicyclopentadiene type epoxy resin used in the present invention, an epoxy resin having a tricyclodecane skeleton derived from dicyclopentadiene can be used without particular limitation. Epoxy resins obtained by epoxidizing dihydroxy compounds having decane as a basic skeleton and epoxy resins obtained by epoxidizing polyhydric phenol compounds having a tricyclodecane skeleton can be mentioned.
In the present invention, a commercially available product can be used as the dicyclopentadiene type epoxy resin. Examples of commercially available products include ADEKA RESIN EP-4088S (manufactured by ADEKA Co., Ltd.) and XD-1000 (manufactured by Nippon Kayaku Co., Ltd.). In the present invention, one of the dicyclopentadiene type epoxy resins described above may be used alone, or two or more of them may be used in combination.
In the present invention, the dicyclopentadiene type epoxy resin preferably contains an epoxy resin represented by the following formula (I). This is because the adhesiveness of the curable resin composition to the aluminum substrate is excellent by containing the epoxy resin represented by the following formula (I).

In the formula, R ¹ and R ² each independently represent a hydrogen atom or a methyl group.

(A) The epoxy resin may contain other epoxy resins in addition to the dicyclopentadiene type epoxy resin. Other epoxy resins mean epoxy resins other than the urethane-epoxy-epoxy resin when the component (B) described later is a urethane-epoxy-epoxy resin. When the (A) epoxy resin contains other epoxy resins, the content of the other epoxy resins in the (A) epoxy resin is preferably 0 to 95% by mass, preferably 25 to 85% by mass, based on the component (A). % by mass is more preferred, and 50 to 75% by mass is even more preferred.

Examples of other epoxy resins include polyglycidyl ether compounds of mononuclear polyhydric phenol compounds such as hydroquinone, resorcinol, pyrocatechol, phloroglucinol; dihydroxynaphthalene, biphenol, methylenebisphenol (bisphenol F), methylenebis(ortho cresol), ethylidenebisphenol, isopropylidenebisphenol (bisphenol A), isopropylidenebis(orthocresol), tetrabromobisphenol A, 1,3-bis(4-hydroxycumylbenzene), 1,4-bis(4-hydroxy cumylbenzene), 1,1,3-tris(4-hydroxyphenyl)butane, 1,1,2,2-tetra(4-hydroxyphenyl)ethane, thiobisphenol, sulfobisphenol, oxybisphenol, phenol novolak, ortho Polyglydyl ether compounds of polynuclear polyhydric phenol compounds such as cresol novolak, ethylphenol novolak, butylphenol novolak, octylphenol novolak, resorcinol novolak, and terpene phenol; ethylene glycol, propylene glycol, butylene glycol, hexanediol, polyglycol, thiodiglycol , glycerin, trimethylolpropane, pentaerythritol, sorbitol, polyglycidyl ethers of polyhydric alcohols such as bisphenol A-alkylene oxide adducts; maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, suberic acid, adipic acid , azelaic acid, sebacic acid, dimer acid, trimer acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid, endomethylenetetrahydrophthalic acid Glycidyl esters of aromatic or alicyclic polybasic acids and homopolymers or copolymers of glycidyl methacrylate; N,N-diglycidylaniline, bis(4-(N-methyl-N-glycidylamino)phenyl ) epoxy compounds having a glycidylamino group such as methane and diglycidylorthotoluidine; vinylcyclohexene diepoxide, dicyclopentanediene diepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4- epoxy-6-methylcyclohexylmethyl-6-methylcyclo epoxidized products of cyclic olefin compounds such as hexanecarboxylate and bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate; epoxidized conjugated diene polymers such as epoxidized polybutadiene and epoxidized styrene-butadiene copolymer; Examples include heterocyclic compounds such as glycidyl isocyanurate. In addition, these polyepoxy compounds may be those internally crosslinked with prepolymers having terminal isocyanates, or those having high molecular weights with polyvalent active hydrogen compounds (polyhydric phenols, polyamines, polyphosphates, etc.).

The curable resin composition of the present invention contains (B) a compound having a polyurethane structure.
In the present invention, the compound having a polyurethane structure is preferably (B1) urethane-modified epoxy resin and/or (B2) block urethane, since a cured product having excellent strength can be obtained.

(B1) As the urethane-modified epoxy resin, for example, the following can be preferably used.
A urethane-modified epoxy resin obtained by reacting (a) an epoxy resin with (b) polyurethane having an isocyanate (NCO) content of 0.1 to 10% by mass.
(b) Polyurethane is obtained by reacting (b-1) a polyhydroxy compound and (b-2) a polyisocyanate compound. The (b-2) polyisocyanate compound is used in an amount that is excessive relative to the (b-1) polyhydroxy compound.

(a) Epoxy resins include, for example, bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin and bisphenol S type epoxy resin; biphenyl type epoxy resins such as biphenyl type epoxy resin and tetramethylbiphenyl type epoxy resin. Resin; naphthalene type epoxy resin; alicyclic epoxy resin such as cyclohexanedimethanol type epoxy resin and hydrogenated bisphenol type epoxy resin; phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin and biphenyl novolak type Novolac type epoxy resins such as epoxy resins; triphenylmethane type epoxy resins; tetraphenylethane type epoxy resins; phenol aralkyl type epoxy resins and the like.
These epoxy resins desirably have hydroxyl groups for reacting with (b) polyurethanes having isocyanate groups.
Among these epoxy resins, it is preferable to use a bisphenol type epoxy resin. This is because a curable resin composition having strong adhesion and toughness can be obtained.

(b-1) Polyhydroxy compounds include, for example, polyether polyols, polyester polyols, polycarbonate polyols, polyesteramide polyols, acrylic polyols and polyurethane polyols.

As the polyether polyol, an adduct of a polyhydric alcohol with an alkylene oxide (molecular weight of about 100 to 5,500) is preferably used.

Examples of the polyhydric alcohol include aliphatic dihydric alcohols such as ethylene glycol, propylene glycol, 1,4-butylene glycol (tetramethylene glycol), and neopentane glycol; glycerin, trioxyisobutane, 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, pentamethylglycerin , pentaglycerin, 1,2,4-butanetriol, 1,2,4-pentanetriol and trihydric alcohols such as trimethylolpropane; erythritol, pentaerythritol, 1,2,3,4-pentanetetrol, 2 Tetrahydric alcohols such as ,3,4,5-hexanetetrol, 1,2,3,5-pentanetetrol and 1,3,4,5-hexanetetrol; pentahydric alcohols such as adonite, arabit and xylite alcohol; hexahydric alcohols such as sorbitol, mannitol and idite;
Preferred polyhydric alcohols among these are dihydric to tetrahydric alcohols, particularly propylene glycol, 1,4-butylene glycol and glycerin.

The polyether polyol can be produced by adding an alkylene oxide having 2 to 4 carbon atoms to the above polyhydric alcohol by a known method so as to obtain a desired molecular weight. Examples of alkylene oxides having 2 to 4 carbon atoms include ethylene oxide, propylene oxide and butylene oxide (tetramethylene oxide), and propylene oxide or butylene oxide is particularly preferred.

Examples of the polyester polyols include conventionally known polyesters produced from polycarboxylic acids and polyhydric alcohols, and polyesters obtained from lactones.
Examples of the polycarboxylic acid include benzenetricarboxylic acid, adipic acid, succinic acid, suberic acid, sebacic acid, oxalic acid, methyladipic acid, glutaric acid, pimelic acid, azelaic acid, phthalic acid, terephthalic acid, isophthalic acid, thio Any suitable carboxylic acid such as dipropionic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid or the like can be used.

Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, and bis(hydroxymethylchlorohexane). , diethylene glycol, 2,2-dimethylpropylene glycol, 1,3,6-hexanetriol, trimethylolpropane, pentaerythritol, sorbitol, glycerin or any suitable polyhydric alcohol such as these can be used. In addition to these polyhydric alcohols, polyhydroxy compounds such as polytetramethylene glycol and polycaprolactone glycol can also be used.

Examples of the polycarbonate polyols include those obtained by a dephenol reaction between a diol and diphenyl carbonate, a dealcohol reaction between a diol and a dialkyl carbonate, or a deglycol reaction between a diol and an alkylene carbonate. Examples of the diol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5- Pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10- decanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane and the like.

(b-2) Polyisocyanate compounds include, for example, propane-1,2-diisocyanate, 2,3-dimethylbutane-2,3-diisocyanate, 2-methylpentane-2,4-diisocyanate, octane-3,6 - diisocyanates, 3,3-dinitropentane-1,5-diisocyanate, octane-1,6-diisocyanate, 1,6-hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate, lysine diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate, metatetramethylxylylene diisocyanate, isophorone diisocyanate (3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate), 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane, diphenylmethane-4, 4'-diisocyanate (MDI), dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI), hydrogenated tolylene diisocyanate and the like, and mixtures thereof. These polyisocyanate compounds may be trimerized isocyanurates.
Among these polyisocyanate compounds, the use of at least one selected from the group consisting of 1,6-hexamethylene diisocyanate, tolylene diisocyanate, isophorone diisocyanate, and the isocyanurate of 1,6-hexamethylene diisocyanate is This is preferable because a curable resin composition exhibiting strong adhesiveness to members can be obtained.

Here, the polyurethane from (b-1) the polyhydroxy compound and (b-2) the polyisocyanate compound can be produced by a conventional method.
The amount of component (b-1) and component (b-2) used is such that component (b-2) is excessive relative to component (b-1), specifically, component (b-1). The amount of the isocyanate group of (b-2) exceeds 1 equivalent, preferably an amount of 1.2 to 5 equivalents, particularly preferably an amount of 1.5 to 2.5 equivalents, relative to 1 equivalent of the hydroxyl group of and By using such an amount, it becomes possible to obtain a polyurethane having an isocyanate content of 0.1 to 10% by mass. The isocyanate content of the obtained polyurethane is preferably 1 to 8% by mass.
Here, the isocyanate content can be measured according to JIS K 1603-1.

A urethane-modified epoxy resin can be produced from (a) a polyepoxy compound and (b-2) polyurethane by a conventional method.
The amount of component (b-1) and component (b-2) used is the mass ratio (former/latter) provided that the amount of component (b-2) used relative to component (b-1) is excessive. is preferably 50/50 to 90/10, more preferably 65/35 to 85/25.
The reaction temperature for producing the urethane-modified epoxy resin, that is, the reaction temperature between the (b-1) polyhydroxy compound and the (b-2) polyisocyanate compound is usually 40 to 140°C, preferably 60 to 130°C. be. In carrying out the modification reaction, known urethane polymerization catalysts for promoting the reaction, such as dioctyltin dilaurate, dibutyltin dilaurate, stannous octoate, stannous octoate, lead octylate, lead naphthenate, and zinc octylate It is also possible to use organometallic compounds such as triethylenediamine and tertiary amine compounds such as triethylamine.

(B2) Blocked urethane is obtained by blocking excessive isocyanate groups of urethane having isocyanate groups with a blocking agent. As the (B2) blocked urethane, those obtained by blocking the isocyanate groups of (B2A) polyurethane having an isocyanate (NCO) content of 0.1 to 10% by mass with (B2B) a blocking agent are preferably used. . (B2A) A polyurethane having an isocyanate (NCO) content of 0.1 to 10% by mass is obtained by reacting (c-1) a polyhydroxy compound and (c-2) a polyisocyanate compound. The (c-2) polyisocyanate compound is used in an amount that is excessive relative to the (c-1) polyhydroxy compound.

(c-1) Polyhydroxy compounds include, for example, the compounds exemplified as (b-1) polyhydroxy compounds.
(c-1) As the polyhydroxy compound, it is preferable to use one or more selected from propylene oxide adducts of glycerin, propylene oxide adducts of castor oil, and polyether polyols such as polytetramethylene glycol, which are excellent even at low temperatures. This is preferable because a curable resin composition that reliably has flexibility can be obtained.

(c-2) Polyisocyanate compounds include, for example, the polyisocyanate compounds exemplified as (b-2) polyisocyanate compounds.
(b-2) As the polyisocyanate compound, at least one selected from the group consisting of 1,6-hexamethylene diisocyanate, tolylene diisocyanate and isophorone diisocyanate is used. It is preferable because a resin composition can be obtained.

(B2A) polyurethane from (c-1) polyhydroxy compound and (c-2) polyisocyanate compound can be produced by a conventional method.
The amount of component (c-1) and component (c-2) used is such that component (c-2) is excessive relative to component (c-1), specifically, component (c-1). The amount of the isocyanate group of (c-2) exceeds 1 equivalent, preferably an amount of 1.2 to 5 equivalents, particularly preferably an amount of 1.5 to 2.5 equivalents, relative to one hydroxyl group of and By using such an amount, it becomes possible to obtain a polyurethane having an isocyanate content of 0.1 to 10% by mass. The isocyanate content of the obtained polyurethane is preferably 1 to 8% by mass.

(B2A) The reaction temperature for producing polyurethane, that is, the reaction temperature between (c-1) polyhydroxy compound and (c-2) polyisocyanate compound is usually 40 to 140°C, preferably 60 to 130°C. . In addition, in order to promote the reaction, a known urethane polymerization catalyst such as dioctyltin dilaurate, dibutyltin dilaurate, stannous octoate, stannous octoate, lead octylate, lead naphthenate, zinc octylate, and other organic metals may be used. It is also possible to use tertiary amine compounds such as compounds, triethylenediamine and triethylamine.

(B2B) blocking agents include, for example, active methylene compounds such as malonate diesters (diethyl malonate, etc.), acetylacetone, acetoacetates (ethyl acetoacetate, etc.); acetoxime, methylethylketoxime (MEK oxime), methylisobutyl Oxime compounds such as ketoxime (MIBK oxime); monohydric alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, heptyl alcohol, hexyl alcohol, octyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, stearyl alcohol, or these isomers; glycol derivatives such as methyl glycol, ethyl glycol, ethyl diglycol, ethyl triglycol, butyl glycol, butyl diglycol; amine compounds such as dicyclohexylamine; phenol, cresol, ethylphenol, n-propylphenol, isopropylphenol , butylphenol, tert-butylphenol, octylphenol, nonylphenol, dodecylphenol, cyclohexylphenol, chlorophenol, bromophenol, resorcinol, catechol, hydroquinone, bisphenol A, bisphenol S, bisphenol F, naphthol and other phenols; ε-caprolactone, ε- caprolactam and the like.
Among these blocking agents, use of one or more selected from the group consisting of dicyclohexylamine, diphenols, ε-caprolactone and ε-caprolactam ensures a curable resin composition having strong adhesion. It is preferable because it is obtained in

The blocking reaction for obtaining (B2) blocked polyurethane from (B2A) polyurethane and (B2B) blocking agent can be carried out by a known reaction method. The amount of the (B2B) blocking agent added to the (B2A) polyurethane is usually 1 to 2 equivalents, preferably 1.05 to 1.5 equivalents, relative to 1 equivalent of free isocyanate groups in the (B2) polyurethane. .

(B2B) The blocking reaction of (B2A) polyurethane with a blocking agent usually takes the method of adding (B2) the blocking agent in the final reaction of the polymerization of (B1) polyurethane. A block polyurethane can also be obtained by adding (B2B) a blocking agent at any stage of (B2B) and allowing it to react.

(B2B) As a method for adding the blocking agent, it is possible to add it at the end of a predetermined polymerization, add it at the beginning of the polymerization, or add a part at the beginning of the polymerization and add the rest at the end of the polymerization. is preferably added at the end of the polymerization. In this case, the isocyanate % (here, the isocyanate % can be measured in accordance with JIS K 1603-1) may be used as a standard for the time when a predetermined polymerization is completed. The reaction temperature for adding the blocking agent is generally 50 to 150°C, preferably 60 to 120°C. The reaction time is usually about 1 to 7 hours. During the reaction, it is also possible to add the above-mentioned known catalyst for urethane polymerization to promote the reaction. Any amount of plasticizer may be added during the reaction.

As the (B2) blocked urethane, in addition to the above-mentioned blocked urethane obtained by reacting the (B2A) component and the (B2B) component, a polyisocyanate compound (for example, those exemplified as the (b-2) component, particularly isocyanurate It is also possible to use a blocked isocyanate obtained by modifying the isocyanate with a blocking agent (for example, those exemplified as the (B2B) component).

From the viewpoint of adhesion, the mixing ratio of the component (A) and the component (B) in the present invention is preferably 0.5:99.5 to 80:20 on a mass basis, the former: the latter. It is more preferably 2:98 to 75:25.

The present invention has one technical feature in the content of the dicyclopentadiene type epoxy resin in the curable resin composition. Specifically, the content of the dicyclopentadiene type epoxy resin is 0.5 to 30 parts by mass, preferably 1 to 20 parts by mass, and particularly It is preferably 3 to 10 parts by mass. If the content of the dicyclopentadiene type epoxy resin is less than 0.5 parts by mass, the effect of improving the adhesion to the aluminum substrate may not be sufficiently obtained, and if it exceeds 30 parts by mass, sufficient strength may be obtained. In terms of cost, it is desirable to use a small amount.

The curable resin composition of the present invention contains (C) a latent curing agent.
The (C) latent curing agent used in the present invention includes, for example, at least one selected from the group consisting of dicyandiamide, modified polyamines, hydrazides, 4,4'-diaminodiphenylsulfone, boron trifluoride amine complex salts and melamine. It is preferable to use one kind. In addition to these, guanamines, imidazoles and the like can also be used as latent curing agents. In the present invention, it is preferable to use dicyandiamide as (C) the latent curing agent. This is because the curing speed of the curable resin composition is increased.

Examples of the modified polyamines include epoxy-modified polyamines, amide-modified polyamines, and Mannich-modified polyamines.

Examples of polyamines used in the modified polyamine include aliphatic polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,2-diaminopropane, polyoxypropylenediamine and polyoxypropylenetriamine; isophorone; diamine, mensenediamine, bis(4-amino-3-methyldicyclohexyl)methane, diaminodicyclohexylmethane, bis(aminomethyl)cyclohexane, N-aminoethylpiperazine, 3,9-bis(3-aminopropyl)-2, Alicyclic polyamines such as 4,8,10-tetraoxaspiro(5.5)undecane; m-phenylenediamine, p-phenylenediamine, tolylene-2,4-diamine, tolylene-2,6-diamine, mesitylene- Mononuclear polyamines such as 2,4-diamine, mesitylene-2,6-diamine, 3,5-diethyltolylene-2,4-diamine, 3,5-diethyltolylene-2,6-diamine; biphenylenediamine, Aromatic polyamines such as 4,4-diaminodiphenylmethane, 2,5-naphthylenediamine, 2,6-naphthylenediamine; 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-isopropylimidazole, 2-un imidazoles such as decylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-aminopropylimidazole;

The epoxy addition-modified products include the polyamines, glycidyl ethers such as phenyl glycidyl ether, butyl glycidyl ether, bisphenol A-diglycidyl ether, bisphenol F-diglycidyl ether, or various epoxy compounds such as carboxylic acid glycidyl esters. It can be produced by reacting with a resin by a conventional method.

The amide-modified product can be produced by reacting the polyamines with carboxylic acids such as adipic acid, sebacic acid, phthalic acid, isophthalic acid and dimer acid in a conventional manner.

The Mannich-modified products are usually obtained by combining the polyamines, aldehydes such as formaldehyde, and phenols having at least one aldehyde-reactive site in the nucleus such as phenol, cresol, xylenol, tertiary-butylphenol, resorcinol, and the like. It can be produced by reacting according to the method.

Examples of the hydrazides include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, and phthalic acid dihydrazide.

The content of component (C) in the curable resin composition of the present invention is not particularly limited, but is usually preferably 1 to 30 parts per 100 parts by mass of components (A) and (B) in total. Parts by mass, particularly preferably 3 to 20 parts by mass. When the content of the component (C) is within the above range, a curable resin composition having good curability and good physical properties can be obtained.

The curable resin composition of the present invention may contain a curing catalyst. The curing catalyst includes phosphine compounds such as triphenylphosphine; phosphonium salts such as tetraphenylphosphonium bromide; - imidazoles such as cyanoethyl-2-methylimidazole; imidazole salts, which are salts of said imidazoles with trimellitic acid, isocyanuric acid, boron, etc.; benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl) Amines such as phenol; Quaternary ammonium salts such as trimethylammonium chloride; 3-(p-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3- Ureas such as phenyl-1,1-dimethylurea, isophorone diisocyanate-dimethylurea, and tolylene diisocyanate-dimethylurea; can. Among these curing catalysts, 3-phenyl-1,1-dimethylurea can be preferably used. These curing catalysts may be used alone or in combination of two or more. The content of the curing catalyst in the curable resin composition of the present invention is not particularly limited, and can be appropriately set according to the application of the curable resin composition.

The curable resin composition of the present invention may contain an inorganic filler. Examples of inorganic fillers include silica such as fused silica and crystalline silica, magnesium hydroxide, aluminum hydroxide, zinc borate, zinc molybdate, calcium carbonate, silicon nitride, silicon carbide, boron nitride, calcium silicate, and potassium titanate. , powders of aluminum nitride, beryllia, zirconia, zircon, fosterite, steatite, spinel, mullite, titania, etc., beads obtained by spheroidizing these powders, and glass fibers. These inorganic fillers may be used alone or in combination of two or more.
The content of the inorganic filler is preferably 10 to 500 parts by mass, more preferably 20 to 300 parts by mass, and 30 to 100 parts by mass with respect to 100 parts by mass of the total amount of components (A) to (C). is particularly preferred.

The curable resin composition of the present invention may further contain additives other than the inorganic filler, if necessary. Examples of additives include non-reactive diluents (plasticizers) such as dioctyl phthalate, dibutyl phthalate, benzyl alcohol and coal tar; fibrous fillers such as glass fiber, pulp fiber, synthetic fiber and ceramic fiber; glass Reinforcing material such as cloth, aramid cloth, carbon fiber; pigment; γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-N' -β-(aminoethyl)-γ-aminopropyltriethoxysilane, γ-anilinopropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltriethoxysilane, Vinyltriethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane Silane coupling agents such as; thickeners; thixotropic agents; antioxidants; light stabilizers; UV absorbers; flame retardants; Used. In the present invention, tacky resins such as xylene resins and petroleum resins can also be used in combination.

The curable resin composition of the present invention can be cured by known methods. Specifically, the curable resin composition of the present invention can be cured by being left at room temperature for several hours to several days. Moreover, the curable resin composition of the present invention can be cured by heating at a heating temperature of 50 to 200° C. for several minutes to several hours.

The curable resin composition of the present invention has excellent adhesion to various substrates, especially aluminum substrates, and has excellent flexibility in a wide range from low temperature to high temperature. In a wide range of fields such as civil engineering and construction fields, it can be suitably used as a structural adhesive for joining metal members and the like, and can be particularly suitably used as an automotive structural adhesive. Moreover, it goes without saying that the curable resin composition of the present invention can also be used for applications such as various coatings, various adhesives, and various molded articles, in addition to structural adhesives.

EXAMPLES The curable resin composition of the present invention will be described in more detail below with reference to Examples and the like, but the present invention is not limited to these Examples and the like. In the following examples, "parts" and "%" mean "mass parts" and "mass%" respectively.

[Production Example 1] (B1) Production of urethane-modified epoxy resin (UEP1) (1) Production of polyurethane Vacuum deaeration was performed for 1 hour at 30 mmHg or less. After cooling the ADEKA POLYETHER G-3000 degassed under reduced pressure to 60° C., 174 parts of tolylene diisocyanate is added and reacted at 90 to 100° C. for 3 hours under a nitrogen stream to obtain an NCO content of 3.6%. was confirmed, the reaction was terminated, and a polyurethane was obtained.

(2) Production of urethane-modified epoxy resin 580 parts of the obtained polyurethane and 0.075 part of dioctyltin dilaurate were added to 2800 parts of ADEKA RESIN EP-4100E (manufactured by ADEKA; bisphenol type epoxy resin, epoxy equivalent: 190). , and reacted at 80-90° C. for 2 hours.
After confirming that the NCO absorption disappeared in the IR absorption spectrum, the reaction was terminated to obtain a urethane-modified epoxy resin (UEP1).

[Production Example 2] (B2) Production of block urethane (BU1) (1) Production of polyurethane 500 parts of ADEKA POLYETHER G-1500 (manufactured by ADEKA; polypropylene glycol glyceryl ether) was added at 100 to 110°C and 30 mmHg or less. was degassed under reduced pressure for 1 hour. After cooling the ADEKA POLYETHER G-1500 degassed under reduced pressure to 60° C., 221 parts of isophorone diisocyanate and 0.075 part of dioctyltin dilaurate are added and reacted at 90 to 100° C. for 3 hours under a nitrogen stream to obtain NCO. After confirming that the content was 5.9%, the reaction was terminated to obtain polyurethane.
(2) Production of block urethane To 781 parts of the obtained polyurethane were added 150 parts of p-tert-butylphenol and 0.025 part of dioctyltin dilaurate, and the mixture was reacted at 90 to 100°C for 3 hours.
After confirming that the absorption of NCO disappeared in the IR absorption spectrum, the reaction was terminated to obtain a block polyurethane (BU1).

[Examples 1 to 8 and Comparative Examples 1 to 3]
The components shown in Table 1 were mixed in the proportions shown in Table 1 to produce curable resin compositions of Examples 1 to 8 and Comparative Examples 1 to 3. The following adhesion test was performed on the produced curable resin composition. The results are shown in [Table 1].

(Al/Al adhesion test)
According to JIS K 6854-3, using aluminum as the adherend, heating the aluminum coated with the curable resin composition at 180 ° C. for 30 minutes and curing the curable resin composition For the test piece obtained, The test was performed at a peel speed of 100 mm/min (unit of measurement; KN/mm). The test was conducted at −20° C., 23° C. and 100° C. respectively.

As is clear from Table 1, the curable resin compositions of Examples 1 to 8, which contain an epoxy resin, a urethane component, and a latent curing agent, and have a dicyclopentadiene-type epoxy resin content within a specific range, Excellent adhesion to aluminum substrates.
In contrast, the curable resin composition of Comparative Example 1, which does not contain a dicyclopentadiene-type epoxy resin as the epoxy resin, did not exhibit any adhesion to the aluminum substrate. In addition, the curable resin composition of Comparative Example 2, in which the urethane-modified epoxy resin was used alone, and the curable resin composition of Comparative Example 3, in which the epoxy resin and block urethane were combined, contained a dicyclopentadiene type epoxy resin. Therefore, the adhesion to the aluminum substrate was insufficient.

Claims (9)

(A) an epoxy resin, (B) a compound having a urethane structure, and (C) a latent curing agent,
(A) the epoxy resin contains a dicyclopentadiene type epoxy resin,
The compound having a urethane structure, which is the component (B), is (B1) a urethane-modified epoxy resin and/or (B2) a block urethane,
A curable resin composition in which the content of the dicyclopentadiene type epoxy resin is 1 to 20 parts by mass per 100 parts by mass of components (A) and (B). The curable resin composition according to claim 1, wherein the dicyclopentadiene type epoxy resin is represented by the following formula (I).

In the formula, R ¹ and R ² each independently represent a hydrogen atom or a methyl group. The urethane-modified epoxy resin as the component (B1) is obtained by reacting (a) an epoxy resin and (b) a polyurethane having an isocyanate content of 0.1 to 10% by mass,
Polyurethane as component (b) is obtained by reacting (b-1) polyhydroxy compound and (b-2) polyisocyanate compound,
3. The curable resin composition according to claim 1 , wherein the polyisocyanate compound (b-2) is used in an excess amount relative to the polyhydroxy compound (b-1). 4. The curable resin composition according to claim 3 , wherein the epoxy resin as component (a) is a bisphenol type epoxy resin. The polyhydroxy compound as component (b-1) is at least one selected from the group consisting of polyether polyols, polycarbonate polyols and polyester polyols,
The polyisocyanate compound as component (b-2) is at least one selected from the group consisting of 1,6-hexamethylene diisocyanate, tolylene diisocyanate, isophorone diisocyanate, and the isocyanurate of 1,6-hexamethylene diisocyanate. The curable resin composition according to claim 3 or 4 . The blocked urethane as component (B2) is obtained by blocking (B2A) polyurethane having an isocyanate content of 0.1 to 10% by mass with (B2B) a blocking agent,
(B2A) component polyurethane is obtained by reacting (c-1) polyhydroxy compound and (c-2) polyisocyanate compound,
2. The curable resin composition according to claim 1 , wherein the amount of the polyisocyanate compound ( c -2) is excessive relative to the polyhydroxy compound (c-1). (c-1) the polyhydroxy compound as the component is a polyether polyol,
7. The curable resin composition according to claim 6 , wherein the polyisocyanate compound as component c-2) is at least one selected from the group consisting of 1,6-hexamethylene diisocyanate, tolylene diisocyanate and isophorone diisocyanate. The latent curing agent (C) is at least one selected from the group consisting of dicyandiamide, modified polyamines, hydrazides, 4,4'-diaminodiphenylsulfone, boron trifluoride amine complex salts, ureas and melamine. , The curable resin composition according to any one of claims 1 to 7 . The curable resin composition according to any one of claims 1 to 8 , which is used as a structural adhesive.