Curable composition and fiber-reinforced composite material

Abstract

To provide a curable composition which enables provision of a cured product having high strength and is suitable for a fiber-reinforced composite material, and a fiber-reinforced composite material which enables provision of a molded article excellent in film peelability, moldability and surface smoothness.SOLUTION: A curable composition contains an epoxy group-containing compound (A), a polyol compound (B) having a hydroxyl equivalent of 125 to 600 g / equivalent, a polyisocyanate compound (C), and a curing agent (D) for an epoxy resin or a curing accelerator (E) for an epoxy resin, wherein the compound (C) contains a first polyisocyanate compound (C-1) having an NCO group content of 33.0 mass% or more and a second polyisocyanate compound (C-2) having an NCO group content of 30.1 mass% or more and 32.9 mass% or less, 15 to 50 mass% of the compound (C-2) is contained, and an NCO / OH ratio is within a range of 1.2 to 3.0.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a curable composition and a fiber-reinforced composite material, in particular to a curable composition for a sheet molding compound and to a sheet molding compound. [Background technology]

[0002] So-called FRP, which is made by reinforcing thermosetting resin with fiber reinforcement, is used in many fields such as industrial parts, housing materials, and automobile parts. Furthermore, fiber-reinforced resin composite materials, which are made by reinforcing thermosetting resin such as epoxy resin and unsaturated polyester resin with carbon fiber as fiber reinforcement, have attracted attention for their lightweight yet excellent heat resistance and mechanical strength, and are being used in various structural applications. In addition, sheet molding compounds (hereinafter sometimes abbreviated as "SMC") are widely used because they use discontinuous fibers as fiber reinforcement, have excellent flowability during molding, and have a wide range of applicable molded shapes. SMCs made of unsaturated polyester resins and vinyl ester resins, which are currently generally known as thermosetting resins for SMC, have problems such as the emission of volatile organic compounds. For this reason, studies are being conducted on SMCs using epoxy resins. As SMCs containing epoxy resin as a main component, epoxy resin compositions and molding materials containing aromatic epoxy resin, alicyclic diamine, epoxy resin curing agent, and aliphatic epoxy resin as essential components are known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6447791 Summary of the Invention [Problem to be solved by the invention]

[0004] The molding material described in Patent Document 1 can give a cured product with relatively excellent strength, but it is very sticky, making film peelability an issue, and has poor moldability and poor surface smoothness of the molded product.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a curable composition which gives a high-strength cured product and is suitable for a fiber-reinforced composite material, and a fiber-reinforced composite material which gives a molded article having excellent film releasability and formability and excellent surface smoothness. [Means for solving the problem]

[0006] The present disclosure includes the following embodiments [1] to [8]. [1] A curable composition comprising an epoxy group-containing compound (A), a polyol compound (B), a polyisocyanate compound (C), and an epoxy resin curing agent (D) or an epoxy resin curing accelerator (E), the polyol compound (B) has a hydroxyl group equivalent in the range of 125 to 600 g / equivalent, The polyisocyanate compound (C) includes a first polyisocyanate compound (C-1) and a second polyisocyanate compound (C-2), The first polyisocyanate compound (C-1) has an NCO group content of 33.0% by mass or more, The second polyisocyanate compound (C-2) has an NCO group content of 30.1% by mass or more and 32.9% by mass or less, The content of the second polyisocyanate compound (C-2) relative to the total amount of the polyisocyanate is 15% by mass or more and 50% by mass or less, A curable composition, characterized in that an NCO / OH ratio, which is a ratio of the number of NCO groups in the polyisocyanate compound (C) to the number of OH groups in the polyol compound (B), is in the range of 1.2 to 3.0. [2] The curable composition according to [1], wherein the epoxy group-containing compound (A) contains a bisphenol-type epoxy resin having an epoxy equivalent in the range of 160 to 260 g / equivalent. [3] The curable composition according to [1] or [2], wherein the epoxy group-containing compound (A) contains a polyglycidyl ether of an aliphatic polyol having 2 to 6 carbon atoms. [4] The epoxy group-containing compound (A) contains a bisphenol-type epoxy resin and a polyglycidyl ether of an aliphatic polyol, The curable composition according to any one of [1] to [3], wherein a mass ratio of the bisphenol type epoxy resin to the polyglycidyl ether of an aliphatic polyol, (bisphenol type epoxy resin) / (polyglycidyl ether of an aliphatic polyol), is in the range of 60 / 40 to 95 / 5. [5] A fiber-reinforced composite material comprising the curable composition according to any one of [1] to [4] and reinforcing fibers. [6] The fiber-reinforced composite material according to claim 5, wherein the reinforcing fibers are carbon fibers. [7] The fiber-reinforced composite material according to [5], which is a sheet molding compound. [8] The fiber-reinforced composite material according to [7], having a carrier film on both sides. Effect of the Invention

[0007] The present invention provides a curable composition which gives a high-strength cured product and is suitable for fiber-reinforced composite materials, and a fiber-reinforced composite material which is excellent in film releasability and moldability and which can give molded products with excellent surface smoothness. The fiber-reinforced composite material of the present invention can be suitably used for various applications such as automobile parts, railroad car parts, aerospace vehicle parts, ship parts, housing equipment parts, sports parts, light vehicle parts, building and civil engineering parts, and exteriors and structures of office automation equipment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention will be described in more detail below. Note that the present invention is not limited to the following embodiments.

[0009] "~" means greater than or equal to the value before the "~", and less than or equal to the value after the "~".

[0010] (Curable composition) A curable composition according to one embodiment of the present invention (curable composition according to the present embodiment) contains an epoxy group-containing compound (A), a polyol compound (B), a polyisocyanate compound (C), and an epoxy resin curing agent (D) or an epoxy resin curing accelerator (E). The polyol compound (B) does not include those corresponding to the component (A). The hydroxyl equivalent of the polyol compound (B) is in the range of 125 to 600 g / equivalent. The polyisocyanate compound (C) includes a first polyisocyanate compound (C-1) and a second polyisocyanate compound (C-2). The NCO group content of the first polyisocyanate compound (C-1) is 33.0 mass% or more, the NCO group content of the second polyisocyanate compound (C-2) is 30.1 mass% or more and 32.9 mass% or less, and the content of the second polyisocyanate compound (C-2) relative to the total amount of the polyisocyanate is 15 mass% or more and 50 mass% or less. The NCO / OH ratio, which is the ratio of the number of OH groups in the polyol compound (B) to the number of NCO groups in the polyisocyanate compound (C), is in the range of 1.2 to 3.0.

[0011] [Epoxy group-containing compound (A)] The epoxy group-containing compound (A) is not particularly limited in its specific structure, and a wide variety of compounds can be used as long as they have an epoxy group in their molecular structure. The epoxy group-containing compound (A) may be used alone or in combination of two or more. The epoxy group-containing compound (A) may have a functional group other than an epoxy group. Among them, a compound having two or more epoxy groups in its molecular structure is preferred, since it will be a curable composition with excellent curing reaction. The ratio of the compound having two or more epoxy groups in the molecular structure to the entire epoxy group-containing compound (A) is preferably 80 mass% or more, and particularly preferably 90 mass% or more.

[0012] Examples of the epoxy group-containing compound (A) include diglycidyloxybenzene, diglycidyloxynaphthalene, biphenol-type epoxy resins, bisphenol-type epoxy resins, polyglycidyl ethers of aliphatic polyols, novolac-type epoxy resins, alicyclic epoxy resins, glycidylamine-type epoxy resins, heterocyclic epoxy resins, glycidyl ester-type epoxy resins, triphenolmethane-type epoxy resins, phenol or naphthol aralkyl-type epoxy resins, phenylene or naphthylene ether-type epoxy resins, oxolidone-modified epoxy resins, brominated epoxy resins thereof, and epoxy resins obtained by elongating these epoxy group-containing compounds with an elongator.

[0013] The epoxy group-containing compound (A) preferably contains a bisphenol type epoxy resin, and more preferably contains a bisphenol type epoxy resin having an epoxy equivalent in the range of 160 to 260 g / equivalent. The epoxy group-containing compound (A) preferably contains a polyglycidyl ether of an aliphatic polyol, and more preferably contains a polyglycidyl ether of an aliphatic polyol having 2 to 6 carbon atoms. It is preferable that the epoxy group-containing compound (A) contains a bisphenol type epoxy resin and a polyglycidyl ether of an aliphatic polyol, and that the mass ratio of the bisphenol type epoxy resin to the polyglycidyl ether of an aliphatic polyol, (bisphenol type epoxy resin) / (polyglycidyl ether of an aliphatic polyol), is in the range of 60 / 40 to 95 / 5.

[0014] Examples of the biphenol type epoxy resin include biphenol compounds such as biphenol and tetramethylbiphenol, and polyglycidyl ethers of one or more alkylene oxide adducts of these biphenol compounds with epihalohydrin.

[0015] Examples of the bisphenol type epoxy resin include bisphenol compounds such as bisphenol A, bisphenol F, bisphenol S, bisphenol fluorene, and biscresol fluorene, and alkylene oxide adducts of these bisphenol compounds that are polyglycidyl etherified with epihalohydrin.

[0016] The polyglycidyl ether of the aliphatic polyol may be, for example, a polyglycidyl ether of one or more of various aliphatic polyol compounds or their alkylene oxide adducts with epihalohydrin. Examples of the aliphatic polyol compound include ethylene glycol, propylene glycol, 1,3-propanediol, 2-methylpropanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1, Examples of the diol compounds include aliphatic diol compounds such as 6-hexanediol, 1,4-bis(hydroxymethyl)cyclohexane, and 2,2,4-trimethyl-1,3-pentanediol; alicyclic diol compounds such as 2,2-bis(4-hydroxyphenyl)propane; and aliphatic polyol compounds with three or more functional groups such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, pentaerythritol, ditrimethylolpropane, and dipentaerythritol.

[0017] The novolac type epoxy resin may be, for example, a novolac resin formed from one or more of various phenolic compounds such as phenol, dihydroxybenzene, cresol, xylenol, naphthol, dihydroxynaphthalene, bisphenol, or biphenol, which is polyglycidyl etherified with epihalohydrin.

[0018] Examples of the alicyclic epoxy resin include those obtained by hydrogenating the biphenol compounds or bisphenol compounds, and those obtained by polyglycidyl etherifying one or more of the alkylene oxide adducts thereof with epihalohydrin, as well as 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, 1-epoxyethyl-3,4-epoxycyclohexane, and the like.

[0019] Examples of the glycidylamine type epoxy resin include N,N-diglycidylaniline, triglycidylaminophenol, tetraglycidylxylenediamine, and 4,4'-methylenebis[N,N-diglycidylaniline].

[0020] Examples of the heterocyclic epoxy resin include 1,3-diglycidyl-5,5-dimethylhydantoin and triglycidyl isocyanurate.

[0021] Examples of the glycidyl ester type epoxy resin include diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl-p-oxybenzoate, and glycidyl dimerate.

[0022] Examples of the extender for epoxy resin include the various biphenol compounds and hydrogenated products thereof, the various bisphenol compounds and hydrogenated products thereof, dibasic acid compounds, and acid group-containing polyester resins.

[0023] Among these, the bisphenol type epoxy resin is preferred because it has excellent strength of the cured product and fiber impregnation when used in a fiber-reinforced composite material, and a bisphenol type epoxy resin having an epoxy equivalent in the range of 160 to 260 g / equivalent is more preferred. The proportion of the bisphenol type epoxy resin in the entire epoxy group-containing compound (A) is preferably 40 mass% or more, more preferably 60 mass% or more, and particularly preferably 70 mass% or more. Furthermore, it is preferably 95 mass% or less, and more preferably 90 mass% or less.

[0024] In addition, in terms of being more excellent in fiber impregnation when used in a fiber-reinforced composite material, the polyglycidyl ether of the aliphatic polyol is preferred, and the polyglycidyl ether of the aliphatic polyol having 2 to 6 carbon atoms is more preferred. The proportion of the bisphenol type epoxy resin in the entire epoxy group-containing compound (A) is preferably 5 mass% or more, more preferably 10 mass% or more. Furthermore, it is preferably 50 mass% or less, more preferably 35 mass% or less.

[0025] When the bisphenol type epoxy resin and the polyglycidyl ether of the aliphatic polyol are used in combination, the mass ratio of the two (bisphenol type epoxy resin) / (polyglycidyl ether of the aliphatic polyol) is preferably in the range of 60 / 40 to 95 / 5, and more preferably in the range of 70 / 30 to 85 / 15.

[0026] Specific examples of the epoxy group-containing compound (A) according to the present embodiment include epoxy resins (A1) such as bisphenol A type epoxy resins, diluent epoxy resins (A2) such as 1,4-butanediol diglycidyl ether, and diluent epoxy resins (A3) such as glycerol polyglycidyl ether. The mass ratio of (A1):(A2):(A3) in the epoxy group-containing compound (A) may be, for example, 70 to 95:2.5 to 15:2.5 to 15, and is preferably 80:10:10. Specific examples of the epoxy resins (A1) such as bisphenol A type epoxy resins, diluent epoxy resins (A2) such as 1,4-butanediol diglycidyl ether, and diluent epoxy resins (A3) such as glycerol polyglycidyl ether include "epoxy resins (A1)", "epoxy diluent (A2)", and "epoxy diluent (A3)" described in the examples below.

[0027] [Polyol compound (B)] The curable composition according to the present embodiment contains a polyol compound (B) having a hydroxyl equivalent in the range of 125 to 600 g / equivalent. The polyol compound (B) does not include those corresponding to the component (A). By using the polyol compound (B), a curable composition can be obtained which is excellent not only in strength of the cured product, but also in fiber impregnation when used in a fiber-reinforced composite material, film releasability when used in a sheet molding compound, and surface smoothness of a molded product.

[0028] The polyol compound (B) has a plurality of hydroxyl groups in its molecular structure and has a hydroxyl group equivalent in the range of 125 to 600 g / equivalent, and the specific structure is not particularly limited, and a wide variety of compounds can be used. Furthermore, as the polyol compound, compounds other than the polyol compound (B) that satisfies the hydroxyl group equivalent may be used. In the present invention, polyol compounds having epoxy groups are treated as the epoxy group-containing compound (A).

[0029] Examples of the polyol compound include aliphatic polyol compounds, dihydroxybenzene, dihydroxynaphthalene, trihydroxybenzene, trihydroxynaphthalene, triphenolalkane, biphenol compounds, bisphenol compounds, alicyclic polyol compounds, novolak resins, phenol or naphthol aralkyl resins, phenylene or naphthylene ether resins, and alkylene oxide adducts thereof.

[0030] Examples of the aliphatic polyol compound include ethylene glycol, propylene glycol, 1,3-propanediol, 2-methylpropanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1 aliphatic diol compounds such as 2,6-hexanediol, 1,4-bis(hydroxymethyl)cyclohexane, and 2,2,4-trimethyl-1,3-pentanediol; alicyclic diol compounds such as 2,2-bis(4-hydroxyphenyl)propane; and aliphatic polyol compounds with three or more functional groups such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, pentaerythritol, ditrimethylolpropane, and dipentaerythritol.

[0031] Examples of the biphenol compound include biphenol and tetramethylbiphenol.

[0032] Examples of the bisphenol compound include bisphenol A, bisphenol F, bisphenol S, bisphenol fluorene, and biscresol fluorene.

[0033] Examples of the alicyclic polyol compound include cyclohexanediol and hydrogenated biphenol compounds and bisphenol compounds.

[0034] The novolak type resin may be, for example, a novolak resin made of one or more of various phenolic compounds such as phenol, dihydroxybenzene, cresol, xylenol, naphthol, dihydroxynaphthalene, bisphenol, and biphenol.

[0035] The polyol compound (B) having a hydroxyl group equivalent in the range of 125 to 600 g / equivalent is preferably an alkylene oxide adduct of various polyol compounds, since it provides a curable composition having excellent strength of the cured product, film peelability when used in a sheet molding compound, and surface smoothness of the molded product, i.e., it is preferable that the compound has a (poly)alkylene oxide structure in its molecular structure. Furthermore, it is more preferable that the compound is an alkylene oxide adduct of the aliphatic polyol compound or the bisphenol compound, and the aliphatic polyol compound has 2 to 6 carbon atoms. In addition, it is more preferable that the hydroxyl group equivalent is in the range of 150 to 400 g / equivalent.

[0036] The amount of the polyol compound (B) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, based on 100 parts by mass of the epoxy group-containing compound (A), in order to obtain a curable composition having excellent strength of the cured product, film peelability when used in a sheet molding compound, and surface smoothness of the molded product. The amount is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, based on 100 parts by mass of the epoxy group-containing compound (A).

[0037] [Polyisocyanate compound (C)] The polyisocyanate compound (C) includes a first polyisocyanate compound (C-1) and a second polyisocyanate compound (C-2). The first polyisocyanate compound (C-1) has an NCO group content of 33.0 mass% or more, preferably 35.0 mass% or less. The second polyisocyanate compound (C-2) has an NCO group content of 30.1 mass% or more and 32.9 mass% or less. The content of the second polyisocyanate compound (C-2) relative to the total amount of the polyisocyanate is 15% by mass to 50% by mass, preferably 20% by mass to 40% by mass, and more preferably 25% by mass to 35% by mass. When the content of the second polyisocyanate compound (C-2) is within the above range, it is possible to appropriately increase the viscosity, maintain the melt viscosity at a certain level or higher during molding, suppress resin leakage from the mold, suppress the amount of blistering, and improve the surface properties of the molded product.

[0038] In addition, the NCO / OH ratio, which is the ratio of the number of OH groups in the polyol compound (B) to the number of NCO groups in the polyisocyanate compound (C), is in the range of 1.2 to 3.0. It is preferably 1.8 to 2.8, and more preferably 2.0 to 2.6. When the NCO / OH ratio is in the above range, a sheet molding compound with less stickiness and good film peelability is obtained, and further, a molded product with excellent surface smoothness is obtained.

[0039] The polyisocyanate compound (C) may be of any structure having a plurality of isocyanate groups in its molecular structure, and may be of any structure. Specific examples include aliphatic diisocyanate compounds such as butane diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and dimer acid diisocyanate; alicyclic diisocyanate compounds such as norbornane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate; toluene diisocyanate, xylylene diisocyanate. aromatic diisocyanate compounds such as tetramethylxylylene diisocyanate, tolidine diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, and polymethylene polyphenyl polyisocyanate; modified products of these isocyanate compounds, such as isocyanurate modified products, biuret modified products, allophanate modified products, carbodiimide modified products, and urethane imine modified products, as well as polyol modified products modified with a polyol having a number average molecular weight of 1,000 or less, such as diethylene glycol or dipropylene glycol.

[0040] Among these, aromatic polyisocyanate compounds or various modified products thereof are preferred, since they give a sheet molding compound that is less sticky and has good film peelability.

[0041] [Epoxy resin curing agent (D) or epoxy resin curing accelerator (E)] The epoxy resin curing agent (D) or the epoxy resin curing accelerator (E) may be any of various compounds generally used as a curing agent or curing accelerator for epoxy group-containing compounds without any particular limitation. The curing agent or curing accelerator may be used alone or in combination of two or more kinds.

[0042] Examples of the curing agent (D) or the curing accelerator (E) include an amine compound, an amide compound, an acid anhydride, a phenolic hydroxyl group-containing compound, a phosphorus compound, an imidazole compound, an imidazoline compound, a urea-based compound, an organic acid metal salt, a Lewis acid, and an amine complex salt.

[0043] Examples of the amine compound include aliphatic amine compounds such as ethylenediamine, tetramethylethylenediamine, diethylenetriamine, hexamethylenediamine, triethylenetetramine, and guanidine derivatives; alicyclic and heterocyclic amine compounds such as piperidine, piperazine, isophoronediamine, and 1,8-diazabicyclo-[5.4.0]-undecene (DBU); aromatic amine compounds such as phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, benzylmethylamine, dimethylbenzylamine, xylylenediamine, and pyridine; and boron trifluoride amine complexes.

[0044] Examples of the amide compound include dicyandiamide and polyamidoamine. Examples of the polyamidoamine include those obtained by reacting an aliphatic dicarboxylic acid such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, or azelaic acid, or a carboxylic acid compound such as a fatty acid or a dimer acid, with an aliphatic polyamine or a polyamine having a polyoxyalkylene chain.

[0045] Examples of the acid anhydride include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0046] Examples of the phenolic hydroxyl group-containing resin include various novolak resins, dicyclopentadiene-phenol addition type resins, phenol or naphthol aralkyl resins, triphenolmethane resins, phenol or naphthol aralkyl resins, phenylene or naphthylene ether resins, and aminotriazine-modified phenol resins.

[0047] Examples of the phosphorus compound include alkyl phosphines such as ethylphosphine and butylphosphine, primary phosphines such as phenylphosphine, dialkyl phosphines such as dimethylphosphine and dipropylphosphine, secondary phosphines such as diphenylphosphine and methylethylphosphine, and tertiary phosphines such as trimethylphosphine, triethylphosphine, and triphenylphosphine.

[0048] The imidazole compound is, for example, imidazole, 1-methylimidazole, 2-methylimidazole, 3-methylimidazole, 4-methylimidazole, 5-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 3-ethylimidazole, 4-ethylimidazole, 5-ethylimidazole, 1-n-propylimidazole, 2-n-propylimidazole, 1-isopropylimidazole, 2-isopropylimidazole, isopropylimidazole, 1-n-butylimidazole, 2-n-butylimidazole, 1-isobutylimidazole, 2-isobutylimidazole, 2-undecyl-1H-imidazole, 2-heptadecyl-1H-imidazole, 1,2-dimethylimidazole, 1,3-dimethylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-phenylimidazole, 2-phenyl-1H-imidazole 4-methyl-2-phenyl-1H-imidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenylimidazole Examples of the isocyanuric acid adduct include socyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-cyanoethyl-2-phenyl-4,5-di(2-cyanoethoxy)methylimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, and 1-benzyl-2-phenylimidazole hydrochloride.

[0049] Examples of the imidazoline compound include 2-methylimidazoline and 2-phenylimidazoline.

[0050] Examples of the urea compound include p-chlorophenyl-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-N,N-dimethylurea, N-(3-chloro-4-methylphenyl)-N',N'-dimethylurea, and 4,4'-methylenebisphenyldimethylurea.

[0051] Among these, amine compounds, amide compounds, imidazole compounds, and urea compounds are preferred because they cure quickly and have excellent strength in the cured product.

[0052] The amount of the curing agent (D) or curing accelerator (E) in the epoxy resin composition is preferably such that, when a compound having a functional group capable of reacting with an epoxy group, such as an amine compound, an amide compound, an acid anhydride, or a phenolic hydroxyl group-containing compound, is used, the functional group or active hydrogen in the curing agent is in the range of 0.5 to 1.2 moles per mole of the epoxy group in the epoxy group-containing compound (A). When a phosphorus compound, an imidazole compound, an imidazoline compound, or a urea-based compound is used, the amount is preferably 0.5 to 20 parts by mass per 100 parts by mass of the epoxy group-containing compound (A). Curing agents or curing accelerators for epoxy group-containing compounds

[0053] [Urethane catalyst (F)] The curable composition of the present invention may contain a urethanization catalyst (F) as necessary. The urethanization catalyst (F) may be used alone or in combination of two or more. Examples of the urethanization catalyst include amine compounds such as triethylamine, dibutylamine, triethylenediamine, and pyridine; phosphorus compounds such as triphenylphosphine and triethylphosphine; organic tin compounds such as dibutyltin dilaurate, octyltin trilaurate, octyltin diacetate, dibutyltin diacetate, and tin octylate; organic zinc compounds such as zinc amine, zinc carboxylate, zinc stearate, and zinc octylate; organic bismuth compounds such as bismuth carboxylate; organic zirconium compounds such as zirconium acetylacetonate and zirconium tetraethanolate; organic aluminum compounds such as aluminum triethoxide; and organic titanium compounds such as titanium tetrabutylate and titanium ethylacetoacetate. Among these, organic zinc compounds and organic bismuth compounds are preferred because they are safer to living organisms and have better storage stability.

[0054] When the urethanization catalyst (F) is used, the amount added is preferably in the range of 0.002 to 1 mass % relative to the total mass of the epoxy group-containing compound (A), the polyol compound (B), the polyisocyanate compound (C), and the epoxy resin curing agent (D) or the epoxy resin curing accelerator (E), and is preferably added at all, and more preferably in the range of 0.01 to 0.8 mass %.

[0055] In addition, a dehydrating agent (G) may be added for the purpose of controlling the urethane reaction in the curable composition. The dehydrating agent (G) may be used alone or in combination of two or more. Examples of the dehydrating agent include silica gel, activated alumina, and molecular sieves. Among these, the molecular sieves are preferred because of their excellent water absorption efficiency. The pore size of the molecular sieves is preferably in the range of 0.1 to 0.5 nm, and more preferably in the range of 0.2 to 0.4 nm. The particle size of the molecular sieves is preferably 50 um or less, and more preferably 10 um or less. When the dehydrating agent (G) is used, the amount of the dehydrating agent (G) added is preferably in the range of 0.1 to 5 mass% based on the total mass of the epoxy group-containing compound (A), the polyol compound (B), the polyisocyanate compound (C), and the epoxy resin curing agent (D) or the epoxy resin curing accelerator (E).

[0056] [Other ingredients] The curable composition of the present invention may contain other components other than the epoxy group-containing compound (A), the polyol compound (B), the polyisocyanate compound (C), the epoxy resin curing agent (D) or the epoxy resin curing accelerator (E), the urethane catalyst, and the dehydrating agent (G). Examples of other components include thermosetting resins other than the components (A) to (E), thermoplastic resins, inorganic fillers, low shrinkage agents, release agents, thickeners, viscosity reducers, pigments, antioxidants, plasticizers, flame retardants, antibacterial agents, ultraviolet stabilizers, reinforcing materials, etc. These other components are appropriately added depending on the desired performance and use of the curable composition, and the amount of addition is also arbitrary. In particular, since the effects of the present invention are more significantly exhibited, the total mass of the epoxy group-containing compound (A), the polyol compound (B), the polyisocyanate compound (C), and the epoxy resin curing agent (D) or the epoxy resin curing accelerator (E) in the curable composition is preferably 80 mass% or more, and particularly preferably 90 mass% or more.

[0057] Since the curable composition of the present invention has excellent fiber impregnation properties when used in a fiber-reinforced composite material, the viscosity at 25°C is preferably 100 mPa·s or more, and more preferably 300 mPa·s or more. Also, the viscosity is preferably 10,000 mPa·s or less, and more preferably 6,000 mPa·s or less. In the present invention, the viscosity of the curable composition is measured within 10 minutes after all the ingredients of the curable composition are mixed.

[0058] (Fiber-reinforced composite materials) A fiber-reinforced composite material of one embodiment of the present invention (fiber-reinforced composite material of this embodiment) contains the curable composition of this embodiment and reinforcing fibers. The fiber-reinforced composite material of the present embodiment is preferably used as a sheet molding compound. The fiber-reinforced composite material of the present embodiment preferably has a carrier film on both sides thereof.

[0059] The curable composition of the present invention is useful as a curable resin material, and the cured product thereof is characterized by excellent heat resistance and strength. It can also be combined with reinforcing fibers to form a fiber-reinforced composite material, and is particularly useful as a matrix resin for sheet molding compounds.

[0060] [Reinforced fiber] The reinforcing fibers used in the present invention may be, for example, those generally used in sheet molding compound applications, and a wide variety of fibers may be used without any particular limitations. Specifically, glass fibers, carbon fibers, silicon carbide fibers, pulp, hemp, cotton, nylon, polyester, acrylic, polyurethane, polyimide, or polyamide fibers made of aramids such as Kevlar and Nomex, etc., may be mentioned. Among them, carbon fibers are preferred because they provide a molded product that is excellent in strength and lightweight. As the carbon fibers, various types such as polyacrylonitrile-based, pitch-based, and rayon-based fibers may be used, and polyacrylonitrile-based fibers are more preferred because of their particularly high strength.

[0061] The carbon fibers are usually cut to a length of 2.5 to 50 mm, but carbon fibers cut to a length of 5 to 40 mm are more preferred because this improves the flowability in the mold during molding and the strength and surface smoothness of the molded product.

[0062] The number of filaments in the fiber bundle of the carbon fiber is preferably in the range of 1,000 to 60,000, and more preferably in the range of 5,000 to 30,000, in order to further improve the impregnation with the curable composition and the strength of the molded article.

[0063] The reinforcing fiber content in the fiber-reinforced composite material can be set as desired depending on the desired properties of the molded product, the application, etc., but in order to obtain a molded product with superior strength, it is preferably in the range of 20 to 80 mass%, and more preferably in the range of 40 to 70 mass%.

[0064] [Manufacturing method of fiber-reinforced composite material (sheet molding compound)] The method for producing the fiber-reinforced composite material (sheet molding compound) of the present invention is not particularly limited, and can be produced by a general method. Specifically, it can be produced by a method including some or all of the following steps: a step of uniformly mixing the curable composition using a mixer such as various mixers, roll mills, kneaders, extruders, etc., a step of applying the curable composition to a carrier film with a uniform thickness, a step of scattering the reinforcing fibers on the resin surface of the obtained carrier film with resin, a step of sandwiching the reinforcing fibers with the resin surface of another carrier film with resin, a step of impregnating the reinforcing fibers with the curable composition by applying pressure with an impregnation roll or impregnation belt, etc., a step of winding up the sheet obtained by the impregnation step into a roll or folding it zigzag, and a step of aging at room temperature or at a temperature of 20 to 60 ° C. The carrier film can be a general one such as a polyethylene film, a polypropylene film, a polyethylene terephthalate, a nylon, or a laminate of multiple films.

[0065] The thickness of the sheet molding compound of the present invention can be appropriately set depending on the desired performance and application, but in order to obtain excellent moldability and strength of the cured product, the thickness is preferably 1 mm or more, more preferably 1.2 mm or more, and particularly preferably 1.5 mm or more. Also, the thickness is preferably 10 mm or less, more preferably 5 mm or less, and particularly preferably 4 mm or less.

[0066] [Sheet molding compound applications] The method of obtaining a molded product from the sheet molding compound of the present invention is not particularly limited, and it can be molded by the same method as that of a general sheet molding compound. One example is heat compression molding, and for example, it can be produced by a method including some or all of the steps of peeling the carrier film from a sheet molding compound having a carrier film on the front and back, stacking one or more sheets of the sheet molding compound from which the carrier film has been peeled off, placing the sheet molding compound in a mold, and molding with a compression molding machine. As described above, the sheet molding compound of the present invention has little stickiness and excellent film peelability, so that a molded product can be obtained efficiently. The temperature of the mold can be set arbitrarily, but is preferably in the range of 110 to 180 ° C., and is preferably heated to the same temperature in advance. The molding pressure of the compression molding machine can be set arbitrarily, but is preferably in the range of 0.1 to 30 MPa. The molding time can be set arbitrarily, but it is preferable to clamp the mold for several tens of seconds to several minutes to form the shape and cure the curable composition. EXAMPLES

[0067] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

[0068] (raw materials) "Epoxy resin (A1)": bisphenol A type epoxy resin "Epiclon (registered trademark) 840" manufactured by DIC Corporation, epoxy equivalent 180 g / equivalent, viscosity 10,000 mPa·s (25°C) "Epoxy diluent (A2)": 1,4-butanediol diglycidyl ether, diluent epoxy resin "XY-622" manufactured by ANHUI XINYUAN Chemical Co., Ltd., epoxy equivalent 115g / equivalent, viscosity 14.9mPa·s (25℃) "Epoxy diluent (A3)": glycerol polyglycidyl ether, diluent epoxy resin "Denacol (registered trademark) EX-313" manufactured by Nagase ChemteX Corporation, epoxy equivalent 141 g / equivalent, viscosity 150 mPa·s (25°C)

[0069] "Polyol (B-1)": Glycerol-based polyether polyol "Sannyx (registered trademark) GP-600" manufactured by Sanyo Chemical Industries, Ltd. (hydroxyl equivalent: 200.4 g / eq) hydroxyl value 280 mg KOH / g, hydroxyl equivalent calculated from hydroxyl value 200 g / eq, viscosity 275 mPa·s (25°C) "Polyol (B-2)": Bisphenol A ethylene oxide adduct "Newpol (registered trademark) BPE-40" manufactured by Sanyo Chemical Industries, Ltd. (hydroxyl group equivalent: 201.8 g / eq)

[0070] "First polyisocyanate compound (C-1)": diphenylmethane diisocyanate "Lupranate (registered trademark) MI" manufactured by BASF INOAC Polyurethanes Co., Ltd. (NCO group content: 33.3 mass% or more) "Second polyisocyanate compound (C-2)": polymethylene polyphenyl polyisocyanate "Lupranate M5S" manufactured by BASF INOAC Polyurethanes Ltd. (NCO group content: 31.4 to 32.6% by mass) "Epoxy resin curing agent (D)": Dicyandiamide "DICY7" manufactured by Mitsubishi Chemical Corporation "Epoxy resin curing accelerator (E)": Alkyl urea curing accelerator "B-605-IM" manufactured by DIC Corporation "Urethane catalyst (F)": Zinc amine catalyst "K-KAT XK-614" manufactured by KING INDUSTRIES "Dehydrating agent (G)": Molecular sieve "Molecular sieve 4A powder" manufactured by Union Showa Co., Ltd. Polypropylene film: Sakai Chemical Industry Co., Ltd. "Carbon fiber": Roving: "T700SC-12000-50C", filament count 12,000, manufactured by Toray Industries, Inc.

[0071] (Examples 1 to 5, Comparative Examples 1 to 4) Curable compositions, sheet molding compounds (fiber-reinforced composite materials) and molded articles were produced in the manner described below, and various evaluation tests were carried out.

[0072] "Preparation of Curable Composition" In Examples 1 to 8 and Comparative Examples 1 to 4, the components were mixed in the ratios shown in Tables 1 and 2 below to obtain curable compositions. The blending compositions of the curable compositions are shown in Tables 1 and 2. The "polymeric MDI ratio" shown in Tables 11 and 2 was calculated by the following formula (1).

[0073] Polymeric MDI ratio [%] = (weight of second polyisocyanate compound (C-2)) / (total weight of first polyisocyanate compound (C-1) and second polyisocyanate compound (C-2)) × 100 ... (1)

[0074] "Manufacturing of sheet molding compounds (fiber reinforced composite materials)" The previously obtained curable composition was applied to a polypropylene film in an average amount of 0.5 kg / m 2On the surface coated with the curable composition, carbon fiber roving ("T700SC-12000-50C" manufactured by Toray Industries, Inc., filament count 12,000) cut to 12.5 mm was sprayed from the air so that there was no fiber directionality and the thickness of the resulting sheet molding compound was uniform. The amount of carbon fiber sprayed was adjusted so that the carbon fiber content of the resulting sheet molding compound was 50 mass%. Another polypropylene film with the same curable composition as above was prepared, and carbon fiber was sandwiched between the surface coated with the curable composition. This was pressed with a roller to impregnate the carbon fiber with the curable composition, and then left to stand for 72 hours under a temperature condition of 40°C, to obtain a sheet molding compound with a thickness of 2 mm as the fiber-reinforced composite material of this embodiment. The weight of the sheet molding compound was 2 kg / m 2 It was.

[0075] "Evaluation of Sheet Molding Compounds (Fiber Reinforced Composite Materials)"

[0076] [Evaluation of handling (film peelability)] The sheet molding compound (fiber reinforced composite material) obtained above was peeled off from a polypropylene film at 25° C., and the peelability was evaluated according to the following criteria. A: The molding material is not sticky and does not leave any residue on the film. B: The molding material is sticky and some of the material remains on the film. C: The molding material and the film are in close contact, and a large amount of adhesion remains on the film.

[0077] [Evaluation of handling (tackiness)] The sheet molding compound (fiber-reinforced composite material) obtained above was peeled off from the film at 25° C., and the tackiness was evaluated according to the following criteria. A: No molding material sticking to fingers B: There is a small amount of molding material on the finger. C: Molding material is stuck to the finger.

[0078] "Manufacturing of Molded Products" The sheet molding compound (fiber-reinforced composite material) obtained above was peeled off from the film and cut into pieces of 260 mm x 260 mm. Two pieces were stacked together to make a 30 x 30 cm 2 The SMC was placed in the center of a flat plate mold and molded at a mold temperature of 150°C for 3 minutes at a pressure of 12 MPa to obtain a flat plate-shaped molded product with a thickness of 2 mm. However, in some cases, the SMC did not stretch sufficiently in the mold, and molded products with the desired shape could not be obtained.

[0079] [Evaluation of bending strength, bending modulus and amount of swelling] Four samples each in the horizontal and vertical directions were cut from the molded article, and a three-point bending test was performed in accordance with JIS K7074 to evaluate the bending strength, bending modulus, and amount of blistering on the molded article surface according to the following criteria. However, for some SMC, the SMC did not stretch sufficiently in the mold, and molded articles with the specified shape could not be obtained, making it impossible to measure.

[0080] "Bending strength" A:280MPa or more C: Less than 280MPa "Flexural modulus" A:18GPa or more C: Less than 18GPa

[0081] "Evaluation of the amount of blistering on the surface of molded products" A: Molded object surface 1m 2 Less than 5 bubbles per unit B: Molded object surface 1m 2 Generates 6-9 bubbles per C: Molded object surface 1m 2 More than 10 bubbles per unit

[0082] The sheet molding compounds (fiber-reinforced composite materials) obtained in Examples 1 to 8 and Comparative Examples 1 to 4 were evaluated for their handling properties (film peelability) and handling properties (tackiness) in accordance with the evaluation methods and criteria described above. The results are also shown for the moldings obtained using them, in terms of molding bending strength (MPa), molding bending modulus (GPa), and number of blisters (pieces / m 2 The evaluation results are shown in Tables 1 and 2.

[0083] [Table 1]

[0084] [Table 2]

[0085] In Tables 1 and 2, the components are as follows: "Epoxy resin (A1)": Bisphenol A type epoxy resin "Epicron 840" manufactured by DIC Corporation "Epoxy Diluent (A2)": Dilution epoxy resin "XY-622" manufactured by ANHUI XINYUAN Chemical Co., Ltd. "Epoxy diluent (A3)": Dilution epoxy resin "Denacol (registered trademark) EX-313" manufactured by Nagase ChemteX Corporation "Polyol (B-1)": Glycerol-based polyether polyol "Sannyx (registered trademark) GP-600" manufactured by Sanyo Chemical Industries, Ltd. (hydroxyl equivalent: 200.4 g / eq) "Polyol (B-2)": Bisphenol A ethylene oxide adduct "Newpol (registered trademark) BPE-40" manufactured by Sanyo Chemical Industries, Ltd. (hydroxyl group equivalent: 201.8 g / eq) "Polyisocyanate compound (C-1)": diphenylmethane diisocyanate "Lupranate (registered trademark) MI" manufactured by BASF INOAC Polyurethanes Co., Ltd. (NCO group content: 33.3 or more) "Polyisocyanate compound (C-2)": Polymethylene polyphenyl polyisocyanate "Lupranate M5S" manufactured by BASF INOAC Polyurethanes Co., Ltd. (NCO group content: 31.4 to 32.6) "Epoxy resin curing agent (D)": Dicyandiamide "DICY7" manufactured by Mitsubishi Chemical Corporation "Epoxy resin curing accelerator (E)": Alkyl urea curing accelerator "B-605-IM" manufactured by DIC Corporation "Urethane catalyst (F)": Zinc amine catalyst "K-KAT XK-614" manufactured by KING INDUSTRIES "Dehydrating agent (G)": Molecular sieve "Molecular sieve 4A powder" manufactured by Union Showa Co., Ltd.

[0086] (Consideration) In Comparative Example 1, the crosslink density was low because the ratio of polymeric MDI was low, which caused the melt viscosity during molding to suddenly drop, making it difficult to apply pressure, and it is believed that many blisters occurred on the surface of the molded product. In Comparative Example 2, the crosslink density was high because the ratio of polymeric MDI was high, which caused the melt viscosity during molding to become too high, and the SMC did not stretch sufficiently in the mold, and it is believed that a molded product with a predetermined shape could not be obtained. In Comparative Example 3, the NCO / OH ratio was low, so the thickening did not proceed sufficiently, which caused the melt viscosity during molding to suddenly drop, making it difficult to apply pressure, and it is believed that many blisters occurred on the surface of the molded product. In Comparative Example 4, the NCO / OH ratio was high, so the thickening proceeded excessively, which caused the SMC to not stretch sufficiently in the mold during molding, and it is believed that a molded product with a predetermined shape could not be obtained.

[0087] In contrast, in Examples 1 to 8, a polyol having a specific molecular structure and hydroxyl equivalent weight was reacted with a polyisocyanate having a specific molecular structure and NCO group content to thicken the resin, thereby achieving a suitable crosslink density. As a result, even when heated during molding, a sudden decrease in viscosity of the resin component was suppressed, so that sufficient pressure was applied to the SMC during molding, and the generation of bubbles (blisters) on the surface of the molded product was suppressed. In addition, in Examples 1 to 8, the impregnation property was improved because the viscosity was reduced by adding polyisocyanate when the carbon fiber was impregnated with the compound. In the maturation process after impregnation, the long-chain polyol having a specific hydroxyl group equivalent reacted with the polyisocyanate having a specific structure, which allowed for a moderate increase in viscosity. As a result, the film peelability of the sheet molding compounds obtained in Examples 1 to 8 was improved. In addition, in Examples 1 to 8, a specified amount of polymeric MDI having an NCO group content of 30.1 mass % or more and 32.9 mass % or less was added, which moderately increased the viscosity, maintained the melt viscosity during molding at a certain level or more, suppressed resin leakage from the mold, and improved the surface properties of the molded product.

Claims

1. A curable composition comprising an epoxy group-containing compound (A), a polyol compound (B), a polyisocyanate compound (C), and an epoxy resin curing agent (D) or an epoxy resin curing accelerator (E), the polyol compound (B) has a hydroxyl group equivalent in the range of 125 to 600 g / equivalent, The polyisocyanate compound (C) contains a first polyisocyanate compound (C-1) and a second polyisocyanate compound (C-2), The NCO group content of the first polyisocyanate compound (C-1) is 33.0% by mass or more, The NCO group content of the second polyisocyanate compound (C-2) is 30.1% by mass or more and 32.9% by mass or less, The content of the second polyisocyanate compound (C-2) relative to the total amount of the polyisocyanate compound (C) is 15% by mass or more and 50% by mass or less, A curable composition characterized in that an NCO / OH ratio, which is a ratio of the number of NCO groups in the polyisocyanate compound (C) to the number of OH groups in the polyol compound (B), is in the range of 1.2 to 3.

0.

2. 2. The curable composition according to claim 1, wherein the epoxy group-containing compound (A) contains a bisphenol type epoxy resin having an epoxy equivalent in the range of 160 to 260 g / equivalent.

3. 2. The curable composition according to claim 1, wherein the epoxy group-containing compound (A) contains a polyglycidyl ether of an aliphatic polyol having 2 to 6 carbon atoms.

4. the epoxy group-containing compound (A) contains a bisphenol-type epoxy resin and a polyglycidyl ether of an aliphatic polyol, The curable composition according to claim 1, wherein the mass ratio of the bisphenol-type epoxy resin to the polyglycidyl ether of the aliphatic polyol (bisphenol-type epoxy resin) / (polyglycidyl ether of the aliphatic polyol) is in the range of 60 / 40 to 95 / 5.

5. A fiber-reinforced composite material comprising the curable composition according to any one of claims 1 to 4 and reinforcing fibers.

6. The fiber-reinforced composite material according to claim 5 , wherein the reinforcing fibers are carbon fibers.

7. 6. The fiber reinforced composite material of claim 5 which is a sheet molding compound.

8. The fiber-reinforced composite material according to claim 7 , which has a carrier film on both sides.

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