JP2013018804A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition whose cured product has high Tg, exhibits excellent physical properties such as impact strength, tensile elongation, and shear bond strength, and achieves mechanical properties such as high toughness well, and which is especially suitable for an epoxy resin composition for a composite material.SOLUTION: The epoxy resin composition comprises: 100 to 70 pts.wt. of bifunctional epoxy resin and 0 to 30 pts.wt. of trifunctional epoxy resin; 50 to 75 pts.wt. of at least one bifunctional phenol selected from a group comprising bisphenols, biphenols, catechols, and hydroquinones; and an imidazole curing catalyst.

Description

  The present invention relates to an epoxy resin composition, and more particularly, to an epoxy resin composition suitable for a composite material.

  Epoxy resin composition is a lightweight material that exhibits excellent mechanical strength comparable to metal by impregnating reinforcing fibers to form a composite material, such as aircraft, rocket, large windmill, hull, car body, etc. Etc.

  As an epoxy resin composition used for a composite material application, an epoxy resin that can be used for a prepreg application containing an epoxy resin and a phenol novolac-based curing agent is disclosed in Patent Document 1. Patent Document 2 discloses an epoxy resin composition for an imidazole-cured composite material. However, none of them has performance capable of achieving mechanical properties such as high toughness in terms of Tg, impact strength, tensile elongation, shear bond strength and the like of the cured product. Furthermore, Patent Document 3 discloses a fiber reinforced resin using a thermoplastic resin obtained by linearly polymerizing an epoxy resin and a bifunctional phenol compound, but it is not an imidazole curing system.

  Further, Patent Document 4 discloses an adhesive for structural materials in which 1 to 20% by weight of a bisphenol compound is blended with respect to an imidazole-cured epoxy resin, which brings about an effect of improving disassembly, and has high toughness. It does not have the performance that can achieve the mechanical characteristics such as.

JP 2002-128867 A JP 2010-265371 A JP 2006-321896 A JP 2006-225544 A

  Accordingly, the present invention has a high Tg, and exhibits excellent performance in physical properties such as impact strength, tensile elongation, shear bond strength, and achieves mechanical properties such as high toughness. An object of the present invention is to provide an epoxy resin composition suitable as an epoxy resin composition for composite materials.

As a result of studying the above problems, the present inventor obtains an epoxy resin having both the characteristics of a thermoplastic resin and the characteristics of a thermosetting resin by curing the epoxy resin together with a bifunctional phenol with an imidazole curing catalyst. As a result, the present inventors have found a resin composition that has a high elongation rate, a high impact strength, and can achieve high toughness and the like.
The present invention therefore provides: (A): 100 parts by weight of epoxy resin,
(B): An epoxy resin composition containing 50 to 75 parts by weight of at least one bifunctional phenol selected from the group consisting of bisphenols, biphenols, catechols and hydroquinones, and (C): an imidazole curing catalyst. It is a thing.
The present invention is also a fiber-reinforced epoxy resin composite material containing the epoxy resin composition and reinforcing fibers.

  With the above-described structure, the cured product of the epoxy resin composition of the present invention has a high Tg and achieves excellent performance in mechanical properties such as impact strength, tensile elongation, and shear bond strength. be able to. For this reason, the epoxy resin composition of the present invention is particularly suitable as an epoxy resin composition for composite materials, and can produce composite materials with high toughness and high mechanical strength. The cured product of the epoxy resin composition of the present invention can be said to have both the properties of a thermoplastic resin and the properties of a thermosetting resin. This is because the use of an imidazole curing catalyst in the present invention results in an epoxy resin. It is assumed that this is due to the fact that the resin and the bifunctional phenols are polymerized linearly, and three-dimensional crosslinking is also performed.

  Therefore, the fiber-reinforced epoxy resin composite material of the present invention can be suitably applied to a large molded product that requires high mechanical performance.

  As the epoxy resin (A), a bifunctional epoxy resin may be an essential component, and a trifunctional or higher functional epoxy resin may be used in combination. The bifunctional epoxy resin is not particularly limited, and examples thereof include catechol diglycidyl ether, resorcin diglycidyl ether, hydroquinone diglycidyl ether, t-butyl hydroquinone diglycidyl ether, and 2,5-di-t-butyl. Mononuclear aromatic diepoxy compounds having one benzene ring, such as hydroquinone diglycidyl ether and diglycidyl phthalate; 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexene carboxylate (example; Celoxide 2021P (trade name, manufactured by Daicel Chemical Industries, Ltd.), alicyclic diepoxy compounds such as limonene dioxide and dicyclopentadiene dioxide; bis (4-hydroxyphenyl) methane diglycidyl ether, bis (4- Hydro Bisphenol-type epoxy resins such as bisphenol-type epoxy compounds such as (ciphenyl) ethanediglycidyl ether and bis (4-hydroxyphenyl) propanediglycidyl ether, and oligomer mixtures obtained by partial condensation thereof; tetramethylbis (4-hydroxyphenyl) Methane diglycidyl ether, tetramethylbis (4-hydroxyphenyl) ethanediglycidyl ether, tetramethylbis (4-hydroxyphenyl) propane diglycidyl ether, tetramethylbis (4-hydroxyphenyl) ether diglycidyl ether, dimethyldi-t -Substitution of substituted bisphenol type epoxy compounds such as butyl bis (4-hydroxyphenyl) sulfide diglycidyl ether and oligomer mixtures in which these are partially condensed Sphenol type epoxy resins; bisphenol fluorene type epoxy resin, biscresol fluorene type epoxy resin, biphenyl type or tetramethylbiphenyl type epoxy resin, diglycidyl ether of dihydroxynaphthalene and oligomer mixture obtained by partial condensation thereof (naphthalene) Type epoxy resins); dimethylolcyclohexane diglycidyl ether, 1,4-cyclohexane diglycidyl ether, 1,3-cyclohexane diglycidyl ether, 1,2-cyclohexane diglycidyl ether, dimethylol dicyclopentadiene diglycidyl ether, etc. Diepoxy compounds of cycloaliphatic alcohols; cyclic fats such as hexahydrophthalic acid diglycidyl ester and hexahydroterephthalic acid diglycidyl ester Diepoxy compounds of aliphatic dicarboxylic acids; diepoxy compounds of aliphatic alcohols such as 1,4-butanediol diglycidyl ether and 1,6-hexanediol diglycidyl ether; Epikote 871 (trade name, manufactured by Mitsubishi Chemical Corporation), Bifunctional epoxy resins such as epoxy resins having a dimer acid skeleton such as Epikote 872 (trade name, manufactured by Mitsubishi Chemical Corporation) can be given. Of these, at least one selected from bisphenol-type epoxy resins is preferable.

  Examples of the tri- or higher functional epoxy resin include cresol novolac epoxy resin, phenol novolac epoxy resin, phenol biphenylene novolac epoxy resin, novolac epoxy resin such as bisphenol A novolac epoxy resin, triglycidyl isocyanurate, Triphenyl glycidyl ether methane type epoxy resin, further, these brominated novolak type epoxy resins, trifunctional type epoxy resins such as brominated epoxy resins, tetraglycidyl metaxylenediamine type epoxy resins, and further brominated epoxies thereof. Polyfunctional resins such as tetrafunctional epoxy resins such as resins, dicyclopentadiene type epoxy resins, xylylene type epoxy resins, tetrakisphenol ethane type epoxy resins, naphthalene type epoxy resins, etc. It can be mentioned carboxymethyl resin. Among these, from the viewpoint of impact strength, an epoxy resin having an aromatic ring (excluding an amine type epoxy resin among epoxy resins having an aromatic ring) is preferable, and the group consisting of a novolac type epoxy resin and a naphthalene type epoxy resin More preferably, it is at least one selected from.

  Tri- or higher functional epoxy resins can improve heat resistance when used in combination. Since trifunctional or higher functional epoxy resin is an optional component, it may not be used, but the blending amount is preferably 0 to 30 parts by weight with respect to 100 to 70 parts by weight of the bifunctional epoxy resin. More preferably, it is 10-30 weight part with respect to 90-70 weight part of bifunctional epoxy resins. In a fiber reinforced composite material application, the composition of the present invention preferably uses a bifunctional epoxy resin and a trifunctional or higher functional epoxy resin in combination.

  The bifunctional phenols (B) are at least one selected from the group consisting of bisphenols, biphenols, catechols and hydroquinones.

  Examples of bisphenols include tetrabromobisphenol A, tetrabromobisphenol F, bisphenol A, bisphenol F, bisphenol S, bisphenol K, bisphenol AD, bisphenol C, and bisphenol AF. Among these, at least one selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, and bisphenol AD is preferable.

  Examples of biphenols include tetramethyl biphenol.

  Examples of catechols include methyl catechol.

  Examples of hydroquinones include methyl hydroquinone.

  Among these bifunctional phenols (B), among these, bisphenols and biphenols are preferable from the viewpoint of high impact strength, and bisphenols are more preferable.

  The bifunctional phenols (B) are used in an amount of 50 to 75 parts by weight with respect to 100 parts by weight of the epoxy resin (A). If it is less than 50 parts by weight or exceeds 75 parts by weight, the impact strength is lowered. Preferably it is 55-65 weight part, More preferably, it is 55-60 weight part.

  The imidazole curing catalyst (C) is not particularly limited, and examples thereof include 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, imidazole, and 1-methyl. Examples thereof include imidazole, 2-methylimidazole, 2-phenylimidazole / isocyanuric acid adduct and the like. Of these, imidazole and 1-methylimidazole are preferable.

  The amount of the imidazole curing catalyst (C) is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, and further 1 to 8 parts by weight per 100 parts by weight of the epoxy resin. preferable.

  The epoxy resin composition of the present invention can have a viscosity suitable for a composite material, preferably a viscosity suitable for a molding method. For example, the viscosity at the time of infusion molding is 300 mPa at 80 ° C.・ S or less is preferable, and the viscosity at the time of prepreg molding is preferably 100 to 1,000 Pa · s at 50 ° C. The viscosity can be measured with a rheometer (for example, AR-G2: manufactured by TA Instruments Japan Co., Ltd.).

  Even if the bifunctional phenols (B) are solid alone, the viscosity of the mixture of the epoxy resin (A), the bifunctional phenols (B) and the imidazole curing catalyst (C) is suitable for composite materials. Can be used, for example, the viscosity at the time of molding may be used.

  The epoxy resin composition of the present invention comprises the above-mentioned essential components: epoxy resin (A), bifunctional phenols (B), and imidazole curing catalyst (C), that is, contains only the above-mentioned essential components. Alternatively, it may contain an optional component other than the above essential components, for example, a solvent, rubber powder, liquid rubber and the like described below.

  The epoxy resin composition of the present invention may use a solvent if necessary for viscosity adjustment or the like. The solvent is not particularly limited. For example, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, cyclohexanone, cyclopentanone, dimethylacetamide, N-methyl-2-pyrrolidone, methyl ethyl ketone, ethyl acetate, propylene glycol monoethyl Examples include ether acetate, isophorone, ethylene glycol monomethyl ether acetate, methyl isobutyl ketone, butyl acetate, dimethylformamide, ethylene glycol monobutyl ether, and ethylene glycol monobutyl ether acetate.

  The amount of the solvent used is preferably 10 to 1000 parts by weight, more preferably 30 to 500 parts by weight, and even more preferably 50 to 300 parts by weight per 100 parts by weight of the epoxy resin.

  The epoxy resin composition of the present invention may be blended with components generally used in an epoxy resin composition for fiber-reinforced epoxy resin composites, if necessary, and particularly rubber powder and liquid rubber may be used. Good. The rubber powder and liquid rubber are not particularly limited, and examples thereof include acrylic powder and carboxy-terminated butadiene-nitrile rubber (CTBN).

  The blending amount of the rubber powder and liquid rubber is preferably 0 to 50 parts by weight, more preferably 5 to 30 parts by weight, and still more preferably 10 to 20 parts by weight per 100 parts by weight of the epoxy resin.

  The epoxy resin composition of the present invention can be produced by mixing each component in a predetermined amount by a known method. For example, a known disperser, mixer, kneader, homogenizer, three rolls, etc. It can obtain by the manufacturing method which has the process of mixing using the means of.

  The fiber-reinforced epoxy resin composite material of the present invention contains the epoxy resin composition of the present invention and reinforcing fibers. As said fiber, the various reinforcing fiber normally used by FRP can be used, For example, a carbon fiber, glass fiber, a polyester fiber, an aromatic polyamide fiber etc. can be used. The fiber may be subjected to surface treatment with a coupling agent or the like, if necessary.

  The blending amount of the reinforcing fiber is not particularly limited, and can be a blending amount usually used in FRP. For example, it can be about 10 to 60% by volume in the composite material. If the blending amount is less than 20% by volume, the surface of the molded product tends to be uneven, warping and undulation tend to increase, and if it exceeds 50% by volume, the fiber tends to be unimpregnated. 20-50 volume% is more preferable.

  The fiber-reinforced epoxy resin composite material of the present invention can be produced by a method of impregnating the reinforcing fiber with the epoxy resin composition of the present invention. In the impregnation step, the epoxy resin composition of the present invention and the reinforcing fiber may be mixed at room temperature (for example, 25 ° C.) to 100 ° C.

  The fiber-reinforced epoxy resin composite material of the present invention may further contain various conventionally known inorganic fillers as long as the effects of the present invention are not impaired. The kind and compounding quantity of an inorganic filler can be suitably selected according to the use and the viscosity of a composition. Examples of the inorganic filler include fused silica powder, quartz glass powder, crystalline silica powder, glass microfiber, talc, alumina powder, calcium silicate powder, calcium carbonate powder, antimony oxide powder, barium sulfate powder, and titanium oxide powder. And aluminum hydroxide powder.

  The blending amount of the inorganic filler is preferably 10 to 1000 parts by weight, more preferably 20 to 500 parts by weight, and further preferably 30 to 300 parts by weight per 100 parts by weight of the epoxy resin.

  Furthermore, the fiber reinforced epoxy resin composite material of the present invention includes, for example, various coupling agents, antifoaming agents, low stress agents, flame retardants, rubber particles, pigments and the like within a range that does not impair the effects of the present invention. Can be contained.

  Examples of the molding method of the fiber reinforced epoxy resin composite material of the present invention include, for example, infusion molding, prepreg molding, hand lay-up method, press molding method, transfer method, injection molding method, panel molding method, autoclave method, filament A winding molding method or the like can be applied.

  The molding conditions are a curing temperature of 100 to 180 ° C., more preferably 120 to 150 ° C., a curing time of 30 to 800 minutes, and more preferably 120 to 300 minutes. When a prepreg is produced, a heating temperature of 25 to 100 is used. ° C, more preferably 40-60 ° C, heating time 30-180 minutes, more preferably 120-180 minutes.

  The fiber-reinforced epoxy resin composite material of the present invention can be applied to large moldings such as aircraft, rockets, large windmills, hulls, and car bodies, and particularly to members for uses that require high mechanical performance. Can do. Further, it can be used for various FRP members by taking advantage of mechanical properties such as high toughness.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the following, the meanings of the abbreviations are as follows.
AER260: Bisphenol A type epoxy resin, Asahi Kasei BPA: Bisphenol A
1MIZ: 1-methylimidazole TPP-PB: tetraphenylphosphonium bromide TBAB: tetrabutylammonium bromide BDMA: benzyldimethylamine HX3792: Novacure, ELM-100 manufactured by Asahi Kasei Chemicals, polyglycidylamine type epoxy resin, DEN438 manufactured by Sumitomo Chemical Co., Ltd. Novolac type epoxy resin, Dow Chemical's HP7200: dicyclopentadiene type epoxy resin, DIC's HP4700: naphthalene type epoxy resin, DIC's BCF: biscresol fluorene, JFE Chemical's BPS-24C: Bisphenol S, Nikka Made by Chemical

Examples 1-6, Comparative Examples 1-5
Preparation of epoxy resin composition Each component was mixed with the mixer by the mixing | blending (weight part) of Table 1, 2, and the epoxy resin composition was obtained, respectively. Next, each epoxy resin composition was cured at 150 ° C. for 180 minutes, and Tg and impact strength were measured. For Example 3, the tensile elongation and shear bond strength were also measured. The results are shown in Tables 1 and 2.

Evaluation method (1) Tg
Conforms to JIS K7121.
(2) Impact resistance strength Conforms to JIS K 7111-1.
(3) Tensile elongation Based on JIS K 7161.
(4) Shear adhesive strength Conforms to JIS K 6850.

  From these results, it was demonstrated that the epoxy resin compositions of Examples 1 to 6 have high Tg, high impact strength, and high toughness. Further, from Example 3, it was proved that the tensile elongation and the shear adhesive strength were also good. On the other hand, the epoxy resin compositions of Comparative Examples 1 to 5 had extremely low impact strength.

Preparation of composite material The epoxy resin compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 5 were impregnated at 80 ° C. with a fiber volume content of 60% into carbon fibers (made by Mitsubishi Rayon Co., Ltd.) as reinforcing fibers. And cured under conditions of 130 ° C./3 hr.
The lamination condition is that carbon fiber unidirectional fabrics are laminated in the order of 45 ° / 0 / −45 ° / 90 ° / 90 ° / −45 ° / 0/45 ° [45/0 / −45 / 90]. _2S condition.
As for the molding method, the epoxy resin composition obtained in Examples 1 to 6 was laminated with carbon fiber on the mold by the VaRTM method, and then sealed with a film, and resin was applied to the fiber reinforcement using vacuum pressure. The composite material was molded by impregnation at a temperature of 80 to 90 ° C. and hardening by applying heat. In any case, a good molded body was obtained. On the other hand, the molded articles of the epoxy resin compositions obtained in Comparative Examples 1 to 5 were more brittle than the molded articles of the examples and had a low impact strength.

Claims (8)

(A): 100 parts by weight of epoxy resin,
(B): An epoxy resin composition comprising 50 to 75 parts by weight of at least one bifunctional phenol selected from the group consisting of bisphenols, biphenols, catechols and hydroquinones, and (C): an imidazole curing catalyst. .   The epoxy resin (A) comprises 100 to 70 parts by weight of a bifunctional epoxy resin as an essential component and 0 to 30 parts by weight of a trifunctional or higher functional epoxy resin as an optional component, and is for a fiber-reinforced composite material. Composition.   The composition according to claim 2, wherein the bifunctional type epoxy resin is a bisphenol type epoxy resin and comprises an epoxy resin (A), a bifunctional phenol (B), and an imidazole curing catalyst (C).   The composition according to claim 2 or 3, wherein the trifunctional or higher functional epoxy resin is at least one selected from the group consisting of a novolac type epoxy resin and a naphthalene type epoxy resin.   The composition according to any one of claims 1 to 4, wherein the bifunctional phenol (B) is a bisphenol.   6. The composition according to claim 5, wherein the bisphenol is at least one selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, and bisphenol AD.   A fiber-reinforced epoxy resin composite material comprising the composition according to any one of claims 1 to 6 and reinforcing fibers.   The composite material according to claim 8, which contains 20 to 50% by volume of reinforcing fibers.