JP2021066766A - Epoxy resin and curable resin composition containing the same - Google Patents

Abstract

To provide an epoxy resin excellent in flexibility and also excellent in heat resistance.SOLUTION: The epoxy resin is obtained by glycidyl-etherifying a polyglycerol alkylene oxide adduct and is represented by the following formula (1). (n is a natural number of 2-20; k, l and m are each a natural number and their sum is 4-30; AO is a C2-4 oxyalkylene group; and G1, G2 and G3 are each a glycidyl group or a hydrogen atom, provided that all of G1, G2 and G3 are not hydrogen atoms.)SELECTED DRAWING: None

Description

The present invention relates to an epoxy resin and a resin composition containing the epoxy resin.

Epoxy resins have excellent heat resistance, adhesiveness, water resistance, mechanical properties and electrical properties, so they are used in a variety of adhesives, paints, civil engineering and building materials, insulating materials for electrical and electronic parts, carbon fiber reinforced composite materials, etc. Used in the field. As the normal temperature or heat-curable epoxy resin, aromatic epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol or cresol novolac type epoxy resin are generally used.

Epoxy resin is a resin having various chemical structures and excellent performance. However, epoxy resins typified by bisphenol A type epoxy resins have poor flexibility, and cracks easily develop from scratches and cracks and are easily destroyed. Further, when used as an adhesive, there is a problem that the peel strength is low. It is known that crack generation and peel strength can be improved by using an epoxy resin having excellent flexibility in combination.

In general, as a method for imparting flexibility to an epoxy resin, a method using a resin composition in which a small amount of a flexible agent such as polypropylene glycol diglycidyl ether is mixed with a general-purpose base resin such as a bisphenol A type epoxy resin can be mentioned. (Non-Patent Documents 1 and 2).

Patent Document 1 proposes a method in which polyethylene glycol diglycidyl ether is used in combination with a bisphenol A type epoxy resin for the purpose of improving flexibility. However, although this method imparts flexibility to the cured product, it has a problem that the heat resistance is lowered. Further, it is generally known that flexibility and heat resistance conflict with each other, and it is difficult to improve heat resistance while maintaining flexibility.

Therefore, there has been a demand for an epoxy resin capable of exhibiting an effect of excellent heat resistance while imparting flexibility to a base resin such as a bisphenol A type epoxy resin.

Review Epoxy Resin, Volume 1, Basic Edition I, P299-300 (2003) Introductory Epoxy Resin, P113-115 (1988)

Japanese Unexamined Patent Publication No. 2010-229266

Therefore, the present invention is to provide an epoxy resin capable of exhibiting an effect excellent in flexibility and heat resistance by blending it with a general-purpose base resin such as a bisphenol A type epoxy resin.

As a result of repeated sincere studies in order to solve the above problems, the present inventors have found that an epoxy resin obtained by glycidyl etherification of a polyglycerin alkylene oxide adduct solves the above problems.

According to the present invention, a cured epoxy resin product having excellent flexibility and heat resistance can be obtained. Therefore, the epoxy resin of the present invention can be used in a wide range of applications such as casting materials, carbon fiber composite materials, adhesives, coating agents, sealing agents, and sealing agents.

Hereinafter, embodiments for carrying out the present invention will be described in more detail, but the scope of the present invention is not limited to this embodiment, and modifications and the like have been added to the extent that the gist of the present invention is not impaired. Also belongs to the present invention. The notation "~" indicating the range includes the upper limit and the lower limit.

（ｎは２〜２０の自然数、ｋ、ｌ、ｍはいずれも自然数であり合計で４〜３０、ＡＯは炭素数２〜４のオキシアルキレン基、Ｇ_１、Ｇ_２、Ｇ_３はグリシジル基または水素原子、ただし、Ｇ_１、Ｇ_２、Ｇ_３はいずれも水素原子であることはない） The present invention is an epoxy resin represented by the following formula (1) obtained by glycidyl etherification of a polyglycerin alkylene oxide adduct.

(N is a natural number of 2 to 20, k, l, m are all natural numbers and are 4 to 30 in total, AO is an oxyalkylene group having 2 to 4 carbon atoms, G ₁ , G ₂ and G ₃ are glycidyl groups or Hydrogen atom, however, G ₁ , G ₂ and G ₃ are not hydrogen atoms)

The epoxy resin of the present invention is a compound obtained by reacting polyoxyalkylene polyglyceryl ether with epichlorohydrin, and can be produced by using a known production method. Specific examples of the polyoxyalkylene polyglyceryl ether include polyoxyethylene diglyceryl ether, polyoxyethylene tetraglyceryl ether, polyoxyethylene hexaglyceryl ether, polyoxyethylene decaglyceryl ether, polyoxypropylene diglyceryl ether, and polyoxypropylene tetra. Glyceryl ether, polyoxypropylene hexaglyceryl ether, polyoxypropylene decaglyceryl ether, polyoxybutyrene glyceryl ether, polyoxybutylene tetraglyceryl ether, polyoxybutylene hexaglyceryl ether, polyoxybutylene decaglyceryl ether and the like are preferable. Polyoxypropylene diglyceryl ether is used.

The average degree of polymerization of the polyglycerin constituting the epoxy resin of the present invention is 2 to 20, and considering the reactivity in the reaction between the polyoxyalkylene polyglyceryl ether and epichlorohydrin and the heat resistance of the obtained cured product, 2 to 20 10 is preferable.

The total number of alkylene oxides added to the polyglycerin constituting the epoxy resin of the present invention is 4 to 30, and 9 to 24 is preferable in consideration of the flexibility and heat resistance of the obtained cured product.

The epoxy resin (A) may contain an epoxy resin other than the epoxy resin represented by the formula (1). For example, a bisphenol A type epoxy resin, a bisphenol A-alkylene oxide adduct diglycidyl ether, or a bisphenol F type epoxy. Resin, bisphenol F-alkylene oxide adduct diglycidyl ether, bisphenol AD type epoxy resin, bisphenol S type epoxy resin, tetramethyl bisphenol A type epoxy resin, tetramethyl bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, 3', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, ε-caprolactone modified 3', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, alkylglycidyl ether as a reactive diluent, Examples of the higher alcohol glycidyl ether, phenyl glycidyl ether, o-cresyl glycidyl ether, m, p-cresyl glycidyl ether, o-phenylphenol glycidyl ether and the like can be mentioned. The reactive diluent is used to adjust the viscosity of the epoxy resin.

The compounding ratio of the epoxy resin represented by the formula (1) in the component (A) is preferably 5 to 50% by weight, more preferably 20 to 40% by weight, in consideration of the flexibility and heat resistance of the cured product. preferable.

The curing agent for the component (B) is not particularly limited, and various ones can be used. For example, an acid anhydride-based curing agent, a polyphenol-based curing agent, an amine-based curing agent, a cationic polymerization initiator, and a radical polymerization initiator can be used. Examples of the latent curing agent include dicyandiamide and amine adduct.

Specific examples of the acid anhydride-based curing agent in the present invention include tetrahydrophthalic anhydride, methyltetrahydrochloride phthalic acid, hexahydrohydride phthalic acid, methylhexahydrohydride phthalic acid, methylnadic acid anhydride, and hydride methylnadic acid anhydride. , Trialkyltetrahydrophthalic anhydride, cyclohexanetricarboxylic acid anhydride, methylcyclohexenetetracarboxylic acid anhydride, maleic anhydride, phthalic anhydride, succinic anhydride, dodecenyl anhydride, pyromellitic anhydride, trimellitic anhydride , Benzophenone tetracarboxylic acid, ethylene glycol bisanhydrotrimelite, glycerinbis (anhydrotrimerite) monoacetate and the like. Among these, considering the workability of handling the compounded resin composition, the characteristics after curing, versatility, etc., methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, which are liquid at room temperature, Methylnadic hydride anhydride is preferred.

The content of the acid anhydride-based curing agent is preferably in the range of 0.5 to 1.5 equivalents with respect to 1 equivalent of the epoxy group of the component (A), and is 0 in consideration of curability and physical properties of the cured product. More preferably, it is in the range of 7. to 1.1 equivalents.

When an acid anhydride-based curing agent is used, a curing accelerator may be used in combination if necessary.

The compound that can be used as a curing accelerator is not particularly limited, but specifically, triphenylbenzylphosphonium tetraphenylborate, tetrabutylphosphonium diethylphosphologithioate, tetraphenylphosphonium bromide, tetrabutylphosphonium acetate, tetra-n- Butylphosphonium bromide, tetra-n-butylphosphonium benzotriazolate, tetra-n-butylphosphonium tetrafluoroborate, tetra-n-butylphosphonium tetraphenylborate, methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, ethyltriphenyl Phosphins such as phosphonium iodide, ethyltriphenylphosphonium acetate, n-butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium tetraphenylborate and quaternary salts thereof, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-phenylimidazole, 1- (2-cyanoethyl) -2-ethyl-4-methylimidazole, 2,4-diamino-6- [2-methylimidazolyl] ethyl-s-triazine , 2-Phenylimidazoline 2,3-dihydro-1-pyrrolo [1,2-a] imidazoles such as benzimidazole, tertiary amines such as tris (dimethylaminomethyl) phenol, benzyldimethylamine, 1,8-diazabicyclo -(5,4,0) -7-Undecene, 1,5-diazabicyclo- (4,3,0) -Nonen-5 and other super-strongly basic organic compounds, zinc octylate, zinc laurate, stearic acid Known compounds such as organic carboxylic acid metal salts such as zinc and tin octylate, metal-organic chelate compounds such as benzoylacetone zinc chelate, dibenzoylmethane zinc chelate and ethylacetate ethyl zinc chelate can be mentioned. These accelerators are appropriately selected according to the requirements for the resin composition such as the time required for curing and the pot life.

The mixing ratio of the curing accelerator is preferably 0 to 1 part by weight, more preferably 0.3 to 0.7 parts by weight, based on 100 parts by weight of the component (A).

Specific examples of the polyphenol-based curing agent in the present invention include phenol novolac resin made from various phenols, xylylene skeleton-containing phenol novolac resin, dicyclopentadiene skeleton-containing phenol novolac resin, biphenyl skeleton-containing phenol novolac resin, and fluorene skeleton-containing phenol. Examples thereof include novolak resin and phenol novolak resin containing a terpene skeleton. The various phenols used above include bisphenol A, bisphenol F, bisphenol S, bisphenol AP, bisphenol C, bisphenol E, bisphenol Z, biphenol, tetramethylbisphenol A, dimethylbisphenol A, tetramethylbisphenol F, dimethylbisphenol F, Fluolene skeletons such as tetramethylbisphenol S, dimethylbisphenol S, tetramethyl-4,4'-biphenol, trishydroxyphenylmethane, resorcinol, hydroquinone, pyrogallol, diisopropyrine, 1,1-di-4-hydroxyphenylfluorene, etc. Examples thereof include phenols, phenolized polybutadienes, phenols, cresols, ethylphenols, butylphenols, octylphenols, naphthols and the like.

The blending ratio of the polyphenol-based curing agent is preferably in the range of 0.5 to 1.5 equivalents with respect to 1 equivalent of the epoxy group of the component (A) in consideration of curability and physical properties of the cured product. More preferably, it is in the range of 8 to 1.2 equivalents.

The amine-based curing agent in the present invention can be used for both normal temperature type and heat type curing agents. Specific examples of the amine-based curing agent in the present invention include polyaminoamide, polyoxyethylene diamine, polyoxypropylene diamine, polyoxybutyrene diamine, polyoxypentylene diamine, polyoxyethylene triamine, polyoxypropylene triamine, and polyoxybutylene triamine. , Polyoxypentylene triamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, m-xylene diamine, trimethylhexamethylenediamine, 2-methylpentamethylenediamine, diethylaminopropylamine, isophoronediamine, 1,3-bisaminomethyl Aliper amines such as cyclohexane, bis (4-aminocyclohexyl) methane, norbornene diamine, 1,2-diaminocyclohexane, laromin C-260, 4,4-diamino-3,3-methyldiphenylmethane, diphenylmethane, metaphenylenediamine , Diaminodiphenylsulfone, N-aminoethylpiperazin and other aromatic amines. Moreover, you may use these modified products, for example, MXDA modified products, IPDA modified products and the like.

The blending ratio of the amine-based curing agent is preferably in the range of 0.5 to 1.5 equivalents in consideration of curability and physical properties of the cured product with respect to 1 equivalent of the epoxy group of the component (A). More preferably, it is in the range of 8 to 1.2 equivalents.

As the cationic polymerization initiator, at least one cation selected from aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium and the like, and at least one anion selected from _{BF 4} , PF ₆ , SbF _{6 and the like.} Examples include onium salts composed of. Such a cationic polymerization initiator may be used alone or in combination of two or more.

Specific examples of the aromatic sulfonium salt-based cationic polymerization initiator include bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate and bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate. , Bis [4- (diphenylsulfonio) phenyl] sulfide bistetrafluoroborate, bis [4- (diphenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, (2-ethoxy-1-methyl-2-oxoethyl) ) Methyl-2-naphthalenyl sulfonium hexafluorophosphate, (2-ethoxy-1-methyl-2-oxoethyl) methyl-2-naphthalenyl sulfonium hexafluoroantimonate, (2-ethoxy-1-methyl-2-) Oxoethyl) methyl-2-naphthalenyl sulfonium tetrafluoroborate, (2-ethoxy-1-methyl-2-oxoethyl) methyl-2-naphthalenyl sulfonium tetrax (pentafluorophenyl) borate, diphenyl-4- (phenylthio) Phenylsulfonium hexafluorophosphate, diphenyl-4- (phenylthio) phenylsulfonium hexafluoroantimonate, diphenyl-4- (phenylthio) phenylsulfonium tetrafluoroborate, diphenyl-4- (phenylthio) phenylsulfonium tetrakis (pentafluorophenyl) borate, Triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, bis [4- (di (4- (2-hydroxyethoxy)) phenyl Sulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluoroantimonate, bis [4- (di (4- (4- (4- (4- (4-) 2-Hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bistetrafluoroborate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, etc. Can be mentioned.

Specific examples of aromatic iodonium salt-based cationic polymerization initiators include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis (pentafluorophenyl) borate, and bis (dodecylphenyl). Iodonium hexafluorophosphate, bis (dodecylphenyl) iodonium hexafluoroantimonate, bis (dodecylphenyl) iodonium tetrafluoroborate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate, 4-methylphenyl-4- (1-) Methylethyl) Phenyliodonium Hexafluorophosphate, 4-Methylphenyl-4- (1-Methylethyl) Phenyliodonium Hexafluoroantimonate, 4-Methylphenyl-4- (1-Methylethyl) Phenyliodonium tetrafluoroborate, 4- Examples thereof include methylphenyl-4- (1-methylethyl) phenyliodonium tetrakis (pentafluorophenyl) borate and the like.

Specific examples of the aromatic diazonium salt-based cationic polymerization initiator include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, and phenyldiazonium tetrakis (pentafluorophenyl) borate.

Specific examples of aromatic ammonium salt-based cationic polymerization initiators include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, and 1-benzyl-2-cyanopyridinium tetra. Fluorobolate, 1-benzyl-2-cyanopyridinium tetrakis (pentafluorophenyl) borate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluorophosphate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluoroantimonate, Examples thereof include 1- (naphthylmethyl) -2-cyanopyridinium tetrafluoroborate and 1- (naphthylmethyl) -2-cyanopyridinium tetrax (pentafluorophenyl) boronate.

The blending ratio of the cationic polymerization initiator is preferably in the range of 0.1 to 10 parts by weight, preferably 0.5 to 10 parts by weight, in consideration of curability and physical properties of the cured product with respect to 100 parts by weight of the epoxy resin (A). More preferably, it is in the range of 6 parts by weight.

When a cationic polymerization initiator is used, a radical polymerization initiator may be used in combination if necessary.

Specific examples of the radical polymerization initiator include, for example, acetophenone-based compounds, benzyl-based compounds, benzophenone-based compounds, thioxanthone-based compounds, oxime ester-based compounds, and the like. Examples of acetophenone compounds include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4'-isopropyl-2-hydroxy-2-methylpropiophenone, and 2-hydroxymethyl-2. -Methylpropiophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, p-dimethylaminoacetonone, p-tershalibutyldichloroacetophenone, p-tershaributyltrichloroacetophenone, p-azidobenzal Acetphenone, 1-Hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -Butanone-1, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether and 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2- Examples thereof include methyl-1-propane-1-one. Examples of the benzyl compound include benzyl and the like. Examples of benzophenone compounds include benzophenone, methyl o-benzoyl benzoate, Michler ketone, 4,4'-bisdiethylaminobenzophenone, 4,4'-dichlorobenzophenone, 4-benzoyl-4'-methyldiphenylsulfide and the like. .. Examples of the thioxanthone compound include thioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone and the like. Examples of the oxime ester compound include ethanone-1- [9-ethyl-6- (2-methylbenzoyl-9H-carbazole-3-yl] -1- (O-acetyloxime), 1- [9-ethyl). -6-benzoyl-9H-carbazole-3-yl-octane-1-one oxime-O-acetate, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole-3-yl] -ethane- 1-Oxime-O-benzoate, 1- [9-n-butyl-6- (2-ethylbenzoyl) -9H-carbazole-3-yl] -ethane-1-one oxime-O-benzoate, etanone-1- [ 9-Ethyl-6- (2-Methyl-4-tetrahydrofuranylbenzoyl) -9H-Carbazole-3-yl] -1- (O-acetyloxime), Etanone-1- [9-Ethyl-6- (2-) Methyl-4-tetrahydropyranylbenzoyl) -9H-carbazole-3-yl] -1- (O-acetyloxime), Etanone-1- [9-ethyl-6- (2-methyl-5-tetrahydrofuranylbenzoyl)) -9H-carbazole-3-yl] -1- (O-acetyloxime), etanone-1- [9-ethyl-6- {2-methyl-4- (2,2-dimethyl-1,3-dioxolanyl)) Methoxybenzoyl} -9H-carbazole-3-yl] -1- (O-acetyloxime), etanone-1- [9-ethyl-6- (2-methyl-4-tetrahydrofuranylmethoxybenzoyl) -9H-carbazole- 3-Il] -1- (O-acetyloxime) and the like can be mentioned.

The blending ratio of the radical polymerization initiator is preferably in the range of 0.1 to 5 parts by weight, preferably 0.5 to 5 parts by weight, in consideration of curability and physical properties of the cured product with respect to 100 parts by weight of the epoxy resin (A). More preferably, it is in the range of 3 parts by weight.

As the latent curing agent in the present invention, a normal curing agent that exerts a curing action by heating and that is generally activated in a temperature range of 80 to 250 ° C. can be used. Specific examples of the latent curing agent include imidazole derivatives such as dicyandiamide, 4,4'-diaminodiphenylsulfone, and 2-n-heptadecylimidazole, dihydrazide isophthalate, N, N-dialkylurea derivatives, and N, N-di. Examples thereof include alkylthiourea derivatives and melamine derivatives.

The blending ratio of the latent curing agent is preferably 3 to 25 parts by weight in consideration of curability and physical properties of the cured product with respect to 100 parts by weight of the component (A), and is in the range of 5 to 10 parts by weight. Is more preferable.

The present invention is not limited to the epoxy resin of the component (A) and the curing agent of the component (B), and the colorant, the antioxidant, the leveling agent, the surfactant, as long as the effects of the invention are not impaired. Inorganic fillers such as UV absorbers, silane coupling agents, inorganic fillers, resin particles, wettability improvers, defoamers, light stabilizers, heat stabilizers, and additives such as calcium carbonate, talc, silica, and barium sulfate. Etc. can be used together.

Specific examples will be shown below, but the present invention is not limited to the following examples. In addition, the unit of the table in the examples is "part by weight" unless otherwise specified.

(Synthesis Example 1)
Polyoxypropylene (9) diglyceryl ether (SC-P750 (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) 1217 g, toluene 1348 g, 3 in a 5 L four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen introduction tube. 3.44 g of boron trifluoride ether complex salt was charged and heated to 65 ° C. While maintaining the internal temperature at 65 ° C., 806 g of epichlorohydrin was added dropwise over 1.5 hours to carry out an aging reaction for 1 hour, and then hydroxylation. 247.7 g of sodium was added, and the mixture was stirred for 3 hours while keeping the internal temperature at 55 ° C. After cooling to 50 ° C., 1050 g of water was added for washing with water, and the salt produced by separating the aqueous phase and unreacted salt were generated. Sodium hydroxide and the catalyst were removed. After repeating washing with water once more, the organic layer was separated and toluene was distilled off under reduced pressure to obtain polyglycidyl ether (a) of polyoxypropylene (9) diglyceryl ether. -1) was obtained. The epoxy equivalent of the epoxy resin (a-1) was 296 g / eq, and the viscosity at 25 ° C. was 292 mPa · s.

(Synthesis Example 2)
Polyoxypropylene (14) diglyceryl ether (SC-P1000 (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) 1371.3 g, toluene 1355 g, in a 5 L four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen introduction tube, 3.30 g of boron trifluoride ether complex salt was charged and heated to 65 ° C. While maintaining the internal temperature at 65 ° C., 662.4 g of epichlorohydrin was added dropwise over 1.5 hours, and the aging reaction was carried out for 1.5 hours. After the reaction, 247 g of sodium hydroxide was added, and the mixture was stirred for 3 hours while keeping the internal temperature at 55 ° C. After cooling to 50 ° C., 879 g of water was added and washed with water. To obtain polyglycidyl ether (a-2) of polyoxypropylene (14) diglyceryl ether. The epoxy equivalent of the epoxy resin (a-2) was 365 g / eq, and the viscosity at 25 ° C. was 300 mPa · s. there were.

(Synthesis Example 3)
Polyoxypropylene (24) diglyceryl ether (SC-P1600 (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) 637 g, toluene 553 g, 3 in a 3 L four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen introduction tube. 0.80 g of boron trifluoride ether complex salt was charged and heated to 65 ° C. While maintaining the internal temperature at 65 ° C., 192 g of epichlorohydrin was added dropwise over 1.5 hours, and the aging reaction was carried out for 1.5 hours. , 74 g of sodium hydroxide was added, and the mixture was stirred for 3 hours while keeping the internal temperature at 55 ° C. After cooling to 50 ° C., 84 g of water was added and washed with water. Polyglycidyl ether (a-3) of polyoxypropylene (24) diglyceryl ether was obtained. The epoxy equivalent of the epoxy resin (a-3) was 547 g / eq, and the viscosity at 25 ° C. was 384 mPa · s.

(Example 1)
30 parts by weight of the epoxy resin (a-1) obtained in Synthesis Example 1, 70 parts by weight of the bisphenol A type epoxy resin, 71 parts by weight of methyltetrahydrophthalic anhydride as an acid anhydride-based curing agent, and 1-benzyl as a curing accelerator. 0.5 part by weight of -2-methylimidazole was mixed at room temperature until uniform to obtain an epoxy resin composition. This composition was cast into a die steel mold and cured in an oven at 100 ° C. for 2 hours and then at 150 ° C. for 3 hours to obtain a cured product.

(Examples 2 and 3, Comparative Example 1)
The same operation as in Example 1 was carried out except that the epoxy resin (A) and the curing agent (B) were changed as shown in Table 1, to obtain an epoxy resin composition and a cured product thereof.

<Bending test (flexural modulus)>
The bending test of the cured epoxy resin was measured according to JIS K7171. An autograph AG-IS20 kN desktop type (manufactured by Shimadzu Corporation) was used as a measuring device, and the flexural modulus was measured at a tensile speed of 2 mm / min. The flexural modulus is an index of flexibility, preferably 3.0 GPa or less, and more preferably 2.7 GPa or less.

<Differential scanning calorimetry (glass transition temperature)>
The glass transition temperature of the cured epoxy resin was measured according to JIS K7121. DSC8230 (manufactured by Rigaku Co., Ltd.) was used as the measuring device. The glass transition temperature is an index of heat resistance, and is preferably 90 ° C. or higher.

Table 1 shows the flexural modulus and the glass transition temperature of the epoxy resin cured products obtained in Examples 1 to 3 and Comparative Example 1.

From the comparison between Examples 1 to 3 and Comparative Example 1 shown in Table 1, a cured product using the epoxy resin composition containing the epoxy resin represented by the formula (1) and the bisphenol A type epoxy resin is a comparative example. Compared with the cured product using the epoxy resin composition composed of the polypropylene glycol diglycidyl ether of No. 1 and the bisphenol A type epoxy resin, the bending elasticity is reduced by 0.6 GPa at the maximum, and the glass transition temperature is improved by 7 to 9 ° C. , The effect of excellent flexibility and heat resistance was shown.

Claims (2)

An epoxy resin represented by the following formula (1) obtained by glycidyl etherification of a polyglycerin alkylene oxide adduct.

(N is a natural number of 2 to 20, k, l, m are all natural numbers and are 4 to 30 in total, AO is an oxyalkylene group having 2 to 4 carbon atoms, G ₁ , G ₂ and G ₃ are glycidyl groups or Hydrogen atom, however, G ₁ , G ₂ and G ₃ are not hydrogen atoms) An epoxy resin (A) containing the epoxy resin according to claim 1 and an epoxy resin other than the epoxy resin represented by the formula (1), an acid anhydride-based curing agent, an amine-based curing agent, a cationic polymerization initiator, and a radical. An epoxy resin composition comprising one or more curing agents (B) selected from the group consisting of a polymerization initiator, a polyphenol polymerization initiator, and a latent curing agent.