Modified epoxy resin, epoxy resin composition, and cured product

Abstract

To provide an epoxy resin and an epoxy resin composition demonstrating high adhesion even after a hygrothermal test.SOLUTION: A modified epoxy resin has a softening point of 50°C or higher and a hydrolyzable chlorine content of 2000 ppm or less. The difference in α-glycol content before and after treatment at 80°C for 30 minutes with an alkaline solution twice in equivalent the total chlorine content in the modified epoxy resin is 50 ppm or less.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Epoxy resins have excellent mechanical and electrical properties after curing, as well as adhesive properties, and therefore have been widely used in a variety of fields, including electronic material sealing materials, paint and coating materials, fiber-reinforced composite materials, and adhesives. In particular, in the field of fiber-reinforced composite materials (hereinafter sometimes referred to as FRP), thermosetting resins containing epoxy resins as the main component are widely used for the purposes of low shrinkage during curing, moldability, adhesion to fibers, heat resistance of the cured product, improved strength, etc. As the epoxy resin, from the viewpoint of achieving both processability and heat resistance, bifunctional epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, and multifunctional epoxy resins such as phenol novolac epoxy resin, cresol novolac epoxy resin, and tetraglycidyldiaminodiphenylmethane are used.

[0003] Patent Document 1 discloses an epoxy resin composition in which the total hydrolyzable chlorine content and α-glycol content of the epoxy resin used are specified. Patent Document 2 discloses a novel epoxy resin having an oxazolidone structure and excellent adhesive properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3322909 [Patent Document 2] JP 2019-176224 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the epoxy resin compositions and cured products using the epoxy resins described in Patent Documents 1 and 2 have a problem in that, although they have high initial adhesive strength, they suffer from a large decrease in adhesive strength after a moist heat test.

[0006] In view of the above-mentioned problems in the conventional techniques, an object of the present invention is to provide an epoxy resin that can retain high adhesive strength even after a wet heat test. [Means for solving the problem]

[0007] Means for Solving the Problems The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that an epoxy resin in which the amount of α-glycol before and after alkali treatment is specified to be equal to or less than a specified amount can solve the above-mentioned problems, thereby completing the present invention. That is, the present invention is as follows.

[0008] [1] A modified epoxy resin having a softening point of 50°C or higher and a hydrolyzable chlorine content of 2000 ppm or less, The difference in the amount of α-glycol before and after treatment at 80°C for 30 minutes in an aqueous alkali solution twice the equivalent amount of the total chlorine in the modified epoxy resin is 50 ppm or less. the law of nature, The compound has the structure represented by the following formula (1) and / or (2): Modified epoxy resin.

[0009] [ka]

[0010] [ka]

[0011] (In formulas (1) and (2), R 1 ~R 4 are each independently Bivalent The functional group has a substituent. In addition, X and Y each represent a structure containing an epoxy group or an oxazolidone ring.

[0012] 〔2〕 The epoxy equivalent value based on JIS-K7236 is 200 (g / eq) or more and 1000 (g / eq) or less. 〔1〕 The modified epoxy resin according to claim 1. 〔3〕 The ratio of the weight average molecular weight distribution and the number average molecular weight distribution (Mw / Mn) in terms of polystyrene measured by gel permeation chromatography is 4.0 or less, and the amount of components having a number average molecular weight of 4,000 or more is 40 mass% or less. Or [2] The modified epoxy resin according to claim 1. 〔4〕 The above [1] to 〔3〕 The modified epoxy resin (A) according to any one of the above items, an epoxy resin (B) other than the modified epoxy resin (A); A hardener (C); A modified epoxy resin composition comprising: 〔5〕 The composition further comprises a plasticizer (D). 〔4〕 The modified epoxy resin composition according to claim 1. 〔6〕 The content of the modified epoxy resin (A) is The amount of the modified epoxy resin (A) and the epoxy resin (B) other than the modified epoxy resin (A) is 10 to 95 parts by mass, [4] or [5] The modified epoxy resin composition according to claim 1. 〔7〕 The above [4] to [6] 2. A cured product of the modified epoxy resin composition according to claim 1. Effect of the Invention

[0013] According to the present invention, an epoxy resin and an epoxy resin composition which exhibit high adhesive strength even after a wet heat test can be obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the best mode for carrying out the present invention (hereinafter, the present embodiment) will be described in detail. It should be noted that the present embodiment is merely an example for explaining the present invention, and is not intended to limit the present invention to the following contents. The present invention can be implemented in various modifications within the scope of the gist thereof.

[0015] [Modified epoxy resin] The modified epoxy resin of the present embodiment is The softening point is 50°C or higher, and the amount of hydrolyzable chlorine is 2000 ppm or less, The difference in the amount of α-glycol before and after treatment at 80℃ for 30 minutes in an alkaline aqueous solution with twice the equivalent amount of the total chlorine in the modified epoxy resin is 50 ppm or less.

[0016] (softening point) The modified epoxy resin of this embodiment has a softening point of 50° C. or higher. If the softening point is 50° C. or higher, the modified epoxy resin can exhibit low elasticity performance and exhibit high toughness in terms of adhesive strength. The softening point is preferably 60° C. or higher, more preferably 70° C. or higher. The softening point of the modified epoxy resin can be measured by the method described in the Examples below. The softening point of the modified epoxy resin can be controlled within the above numerical range by adjusting the molecular skeleton and molecular weight.

[0017] (Amount of hydrolyzable chlorine) The modified epoxy resin of the present embodiment has a hydrolyzable chlorine content of 2000 ppm or less, preferably 1800 ppm or less, and more preferably 1500 ppm or less. Here, "hydrolyzable chlorine" refers to chlorine that is added during the synthesis of epoxy resin and undergoes a dechlorination oxidation reaction relatively easily. By controlling the amount of hydrolyzable chlorine to 2000 ppm or less, water absorption can be reduced, and a decrease in adhesive strength after a moisture absorption test can be suppressed. The amount of hydrolyzable chlorine is preferably 0.1 ppm or more, more preferably 0.5 ppm or more, and further preferably 1.0 ppm or more. By containing hydrolyzable chlorine, a curing accelerating effect occurs. The amount of hydrolyzable chlorine in the modified epoxy resin can be measured by the method described in the Examples below. The amount of hydrolyzable chlorine in the modified epoxy resin can be controlled within the above numerical range by adjusting the reaction conditions during synthesis or by carrying out a dechlorination reaction called a dechlorination reaction.

[0018] The modified epoxy resin of this embodiment has an α-glycol content difference of 50 ppm or less before and after treatment at 80° C. for 30 minutes with an aqueous alkali solution in an amount twice the equivalent of the total chlorine content in the modified epoxy resin. The total chlorine content in the modified epoxy resin can be determined in accordance with JIS K7246, as described below. The difference in the amount of α-glycol before and after treatment at 80° C. for 30 minutes using an aqueous alkali solution of twice the amount is determined, and the difference is set to 50 ppm or less, preferably 40 ppm or less, and more preferably 25 ppm or less. The small difference in the amount of α-glycol before and after treatment with the alkaline aqueous solution means that the amount of hydroxyl groups that are generated during curing and are not involved in the substrate surface, i.e., the amount of hydroxyl groups in the cured product, is reduced. As a result, the water absorption rate during a moisture absorption test can be reduced, and a decrease in adhesive strength can be suppressed. The details of the mechanism are as follows: when applied to fiber-reinforced plastics, when hydroxyl groups are generated after bonding with the fiber surface during hardening, they act as hardening defects, which are presumed to be the cause of a decrease in compressive strength, including after water absorption and impact. The difference in α-glycol before and after the predetermined treatment with the above-mentioned alkaline aqueous solution is preferably 0.1 ppm or more, more preferably 0.5 ppm or more, and even more preferably 1.0 ppm or more. By having a difference of 0.1 ppm or more, the cured product after curing does not become too hard, and toughness is imparted to the cured product. Examples of a method for controlling the difference in the amount of α-glycol before and after the predetermined treatment with the alkaline aqueous solution as described above within the above numerical range include a method for adjusting the amount of water during epoxy modification, a method for selecting a catalyst used during modification, and a method for selecting the type of solvent in which the catalyst is dissolved. By carrying out these methods, the amount of hydroxyl groups generated during modification can be reduced, and the side reaction of the hydroxyl groups bonding with the modifying agent can be suppressed.

[0019] The epoxy resin raw material used in the production of the modified epoxy resin of this embodiment is not limited to the following as long as the effects of the present invention can be achieved. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, tetrabromobisphenol A type epoxy resin, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, tetrabromobiphenyl type epoxy resin, diphenyl ether type epoxy resin, benzophenone type epoxy resin, phenyl benzoate type epoxy resin, diphenyl sulfide type epoxy resin, diphenyl sulfoxide type epoxy resin, diphenyl sulfone type epoxy resin, diphenyl disulfide type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, hydroquinone type epoxy resin, methylhydroquinone type epoxy resin, dibutyl hydroxyl type epoxy resin, methyl ... bifunctional epoxy resins such as non-type epoxy resins, resorcin type epoxy resins, methylresorcin type epoxy resins, catechol type epoxy resins, and N,N-diglycidylaniline type epoxy resins; trifunctional epoxy resins such as N,N-diglycidylaminobenzene type epoxy resins, o-(N,N-diglycidylamino)toluene type epoxy resins, and triazine type epoxy resins; tetrafunctional epoxy resins such as tetraglycidyldiaminodiphenylmethane type epoxy resins and diaminobenzene type epoxy resins; multifunctional epoxy resins such as phenol novolac type epoxy resins, cresol novolac type epoxy resins, triphenylmethane type epoxy resins, tetraphenylethane type epoxy resins, dicyclopentadiene type epoxy resins, naphthol aralkyl type epoxy resins, and brominated phenol novolac type epoxy resins; and alicyclic epoxy resins.

[0020] The modified epoxy resin of the present embodiment preferably contains a structure represented by the following formula (1) and / or (2).

[0021] [ka]

[0022] [ka]

[0023] (In formulas (1) and (2), R 1 ~R 4 Each of X and Y independently represents a divalent or higher functional group, which may have a substituent. X and Y each represent a structure containing an epoxy group or an oxazolidone ring.

[0024] Since the modified epoxy resin of the present embodiment contains the structure represented by the above formula (1) and / or (2), the storage stability of the modified epoxy resin composition containing the modified epoxy resin of the present embodiment is improved, and the cured product thereof has extremely excellent heat resistance and fracture toughness.

[0025] The modified epoxy resin containing the structure represented by the formula (1) or (2) is not particularly limited, but for example, it can be prepared in an approximately theoretical amount by reacting an isocyanate compound with a glycidyl compound in the presence of an oxazolidone ring-forming catalyst.

[0026] <Isocyanate compounds> The isocyanate compound used as a raw material includes, but is not limited to, methane diisocyanate, butane-1,1-diisocyanate, ethane-1,2-diisocyanate, butane-1,2-diisocyanate, transvinylene diisocyanate, propane-1,3-diisocyanate, butane-1,4-diisocyanate, 2-butene-1,4-diisocyanate, 2-methylbutene-1,4-diisocyanate, 2-methylbutane-1,4-diisocyanate, pentane-1,5-diisocyanate, 2,2-dimethyl ... hexane-1,5-diisocyanate, hexane-1,6-diisocyanate, heptane-1,7-diisocyanate, octane-1,8-diisocyanate, nonane-1,9-diisocyanate, decane-1,10-diisocyanate, dimethylsilane diisocyanate, diphenylsilane diisocyanate, ω,ω'-1,3-dimethylbenzene diisocyanate, ω,ω'-1,4-dimethylbenzene diisocyanate, ω,ω'-1,3-dimethylcyclohexane diisocyanate, ω,ω'-1,4-dimethylcyclohexane diisocyanate, ω,ω'-1,4-dimethylnaphthalene diisocyanate, ω,ω'-1,5-dimethylnaphthalene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-methylbenzene-2,4-diisocyanate, 1-methylbenzene-2,5-diisocyanate, 1-methylbenzene Zene-2,6-diisocyanate, 1-methylbenzene-3,5-diisocyanate, diphenylether-4,4'-diisocyanate, diphenylether-2,4'-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, biphenyl-4,4'-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, 2,3'-dimethoxybisphenyl-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxydiphenylmethane-4,Bifunctional isocyanate compounds such as 4'-diisocyanate, 4,4'-dimethoxydiphenylmethane-3,3'-diisocyanate, diphenylsulfite-4,4'-diisocyanate, and diphenylsulfone-4,4'-diisocyanate; Polyfunctional isocyanate compounds such as polymethylene polyphenylisocyanate, triphenylmethane triisocyanate, and tris(4-phenylisocyanate thiophosphate)-3,3',4,4'-diphenylmethane tetraisocyanate; Examples of the isocyanate compound include polymers such as dimers and trimers of the above-mentioned isocyanate compounds, blocked isocyanates masked with alcohol or phenol, and bis-urethane compounds.

[0027] These isocyanate compounds may be used alone or in combination of two or more.

[0028] Among the above-mentioned isocyanate compounds, from the viewpoint of a tendency to improve heat resistance, preferred are bifunctional or trifunctional isocyanate compounds, more preferred are bifunctional isocyanate compounds, and further preferred are 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone), 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate (benzene), 1-methylbenzene-2,4-diisocyanate, 1-methylbenzene-2,5-diisocyanate, 1-methylbenzene-2,6-diisocyanate, 1-methylbenzene-3,5-diisocyanate (toluene), 3,3'-dimethylbiphenyl-4,4'-diisocyanate, and the like. The bifunctional isocyanate compound has one or more skeletons selected from diisocyanate, 2,3'-dimethoxybisphenyl-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxydiphenylmethane-4,4'-diisocyanate, 4,4'-dimethoxydiphenylmethane-3,3'-diisocyanate (diphenylmethane), ω,ω'-1,4-dimethylnaphthalene diisocyanate, ω,ω'-1,5-dimethylnaphthalene diisocyanate (naphthalene), polymethylene polyphenyl isocyanate (polymethylene polyphenylene polyphenyl), and (hexane-1,6-diisocyanate hexamethylene).

[0029] <Catalyst and oxazolidone ring forming catalyst> The catalyst used to obtain the modified epoxy resin of the present embodiment is not particularly limited, but a catalyst that selectively produces an oxazolidone ring in the reaction between a glycidyl compound and an isocyanate compound is preferred. Examples of such oxazolidone ring-forming catalysts include, but are not limited to, lithium compounds such as lithium chloride and butoxylithium, complex salts such as boron trifluoride, aqueous alkali solutions such as an aqueous potassium hydroxide solution and an aqueous sodium hydroxide solution, ammonium hydroxide salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide, quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, and tetrabutylammonium bromide, dimethylaminoethanol, triethylamine, tributylamine, and benzyldimethyl amines, tertiary amines such as N-methylmorpholine; phosphines such as triphenylphosphine; phosphonium compounds such as allyltriphenylphosphonium bromide, diallyldiphenylphosphonium bromide, ethyltriphenylphosphonium chloride, ethyltriphenylphosphonium iodide, tetrabutylphosphonium acetate / acetic acid complex, tetrabutylphosphonium acetate, tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, and tetrabutylphosphonium iodide; combinations of triphenylantimony and iodine; imidazoles such as 2-phenylimidazole and 2-methylimidazole; and the like. These catalysts can be used alone or in combination of two or more. Among these, ammonium salts, phosphonium compounds, imidazoles, and the like are preferred because they can reduce the difference in the amount of α-glycol before and after the predetermined treatment with the above-mentioned aqueous alkaline solution.

[0030] The modified epoxy resin of the present embodiment preferably has an epoxy equivalent value based on JIS-K7236 of 200 (g / eq) or more and 1000 (g / eq) or less, more preferably 220 (g / eq) or more, and even more preferably 240 (g / eq) or more. By setting the epoxy equivalent to 200 (g / eq) or more, distortion during curing can be prevented, and the physical properties of the cured product can be improved. The upper limit of the epoxy equivalent is more preferably 900 (g / eq) or less, and even more preferably 800 (g / eq) or less. Since the epoxy equivalent is 1000 (g / eq) or less, this product has good curing properties and easy handling. The epoxy equivalent of the modified epoxy resin can be controlled within the above numerical range by adjusting the epoxy species of the raw material and the modification rate (modification equivalent / epoxy equivalent) of the modified material.

[0031] (molecular weight distribution) The modified epoxy resin of the present embodiment preferably has a ratio of weight average molecular weight distribution to number average molecular weight (molecular weight distribution) determined by gel permeation chromatography of 4.0 or less, more preferably 3.5 or less, and even more preferably 3.3 or less. When the molecular weight distribution is in this range, the modified epoxy resin has excellent fracture toughness. The molecular weight distribution of the modified epoxy resin can be measured by the method described in the Examples below. The molecular weight distribution of the modified epoxy resin can be controlled within the above numerical range by adjusting the reaction conditions in addition to the epoxy species of the raw material and the modification rate (modification equivalent / epoxy equivalent) of the modified material.

[0032] In the epoxy resin of the present embodiment, the amount of components having a number average molecular weight of 4000 or more is preferably 40% by mass or less, as a polystyrene-equivalent value measured by gel permeation chromatography. More preferably, it is 35% by mass or less, and even more preferably, it is 30% by mass or less. When the amount of components having a number average molecular weight of 4000 or more is within the above range, the modified epoxy resin has low melt viscosity and excellent solvent solubility. The amount of components having a number average molecular weight of 4000 or more in the modified epoxy resin can be controlled within the above numerical range by adjusting the reaction conditions.

[0033] [Modified epoxy resin composition] The modified epoxy resin composition of the present embodiment comprises: The modified epoxy resin (A) of the present embodiment described above, an epoxy resin (B) other than the modified epoxy resin (A); and a curing agent (C). The modified epoxy resin composition of the present embodiment may further contain a plasticizer (D), a filler (E), and other curing components (F). The epoxy resin (B), hardener (C), plasticizer (D), filler (E), and other hardening components (F) are described below.

[0034] (Epoxy resin (B)) The epoxy resin (B) is not particularly limited, and various known epoxy resins can be appropriately selected and used. For example, bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, tetrabromobisphenol A type epoxy resin, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, tetrabromobiphenyl type epoxy resin, diphenyl ether type epoxy resin, benzophenone type epoxy resin, phenyl benzoate type epoxy resin, diphenyl sulfide type epoxy resin, diphenyl sulfoxide type epoxy resin, diphenyl sulfone type epoxy resin, diphenyl disulfide type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, hydroquinone type epoxy resin, methylhydroquinone type epoxy resin, dibutylhydroquinone type epoxy resin, resorcinol type epoxy resin, methylresorcinol type epoxy resin, catechol type epoxy resin, and N,N-diglycidylaniline type epoxy resin; N,N-diglycidylaminobenzene type epoxy resin, o-(N, trifunctional epoxy resins such as N-diglycidylamino)toluene type epoxy resins and triazine type epoxy resins; tetrafunctional epoxy resins such as tetraglycidyldiaminodiphenylmethane type epoxy resins and diaminobenzene type epoxy resins; multifunctional epoxy resins such as phenol novolac type epoxy resins, cresol novolac type epoxy resins, triphenylmethane type epoxy resins, tetraphenylethane type epoxy resins, dicyclopentadiene type epoxy resins, naphthol aralkyl type epoxy resins and brominated phenol novolac type epoxy resins; aliphatic epoxy resins and alicyclic epoxy resins which can also be used as reactive diluents such as 2-ethylhexyl glycidyl ether, cyclohexane dimethanol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, hydrogenated bisphenol A type epoxy resins and silicone modified epoxy resins. These can be used alone or in combination of two or more.

[0035] The proportion of the modified epoxy resin (A) component in the modified epoxy resin composition of the present embodiment is preferably 10 to 95 parts by mass, more preferably 20 to 90 parts by mass, and even more preferably 35 to 85 parts by mass, when ((A)+(B)) is 100 parts by mass, from the viewpoint of toughness. When the proportion of component (A) is within the above range, the balance between fracture toughness and the temperature at which the elastic modulus begins to decrease tends to be good.

[0036] (Hardening agent (C)) The curing agent (C) is not particularly limited and various known curing agents can be appropriately selected and used. From the viewpoint of the reaction rate during curing, however, it is preferable that the curing agent be at least one selected from the group consisting of guanidine derivatives, aromatic amine compounds, and novolac-type phenolic resins. These guanidine derivatives, aromatic amine compounds and novolak-type phenolic resins can be used alone or in combination of two or more.

[0037] Examples of the guanidine derivative include, but are not limited to, dicyandiamide derivatives such as dicyandiamide, dicyandiamide-aniline adduct, dicyandiamide-methylaniline adduct, dicyandiamide-diaminodiphenylmethane adduct, and dicyandiamide-diaminodiphenyl ether adduct; guanidine salts such as guanidine nitrate, guanidine carbonate, guanidine phosphate, guanidine sulfamate, and aminoguanidine bicarbonate; acetyl guanidine, diacetyl guanidine, propionyl guanidine, dipropionyl guanidine, cyanoacetyl guanidine, guanidine succinate, diethylcyanoacetyl guanidine, dicyandiamide, N-oxymethyl-N'-cyanoguanidine, and N,N'-dicarbethoxyguanidine.

[0038] Examples of aromatic amine compounds include, but are not limited to, metaphenylenediamine, paraphenylenediamine, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl methane, and 4,4'-diaminodiphenyl ether.

[0039] Examples of novolac-type phenolic resins include, but are not limited to, phenol novolac, bisphenol A novolac, cresol novolac, naphthol novolac, and the like.

[0040] The amount of the curing agent (C) is not particularly limited and is appropriately set according to the desired design, but when the curing agent (C) is a guanidine derivative, it is preferably 1 to 9 mass% based on the total amount of the isocyanate-modified epoxy resin (A), when the curing agent (C) is an aromatic amine compound, it is preferably 10 to 50 mass% based on the total amount of the isocyanate-modified epoxy resin (A), and when the curing agent (C) is a novolac type phenolic resin, it is preferably 20 to 60 mass% based on the total amount of the isocyanate-modified epoxy resin (A). Setting the amount of the curing agent (C) to the above range is suitable from the viewpoint of suppressing the decrease in crosslink density and Tg of the cured product and ensuring moisture resistance.

[0041] (Plasticizer (D)) From the viewpoint of improving fracture toughness, the modified epoxy resin composition of the present embodiment preferably further contains a plasticizer (D). Examples of the plasticizer (D) include thermoplastic elastomers and crosslinked rubbers.

[0042] Examples of the thermoplastic elastomer include polyester-based thermoplastic elastomers and polyamide-based thermoplastic elastomers. Polyamide-based thermoplastic elastomers are preferred because they tend to provide fiber-reinforced composite materials with superior physical properties such as compressive strength and interlaminar shear strength.

[0043] Examples of the crosslinked rubber include acrylonitrile-butadiene copolymers and styrene-butadiene copolymers, with acrylonitrile-butadiene copolymers being preferred since they tend to have better compatibility with epoxy resins.

[0044] The content of the plasticizer (D) is preferably 1 to 30 mass %, more preferably 2 to 20 mass %, based on the entire modified epoxy resin composition. By making the content of the plasticizer (D) 30 mass % or less, it is possible to prevent the resin viscosity from increasing and the resin from impregnating the prepreg poorly. On the other hand, by making it 1 mass % or more, it is possible to maintain the tackiness of the prepreg well and suppress molding defects.

[0045] (Filler (E)) The modified epoxy resin composition of the present embodiment may further contain a filler (E). The inclusion of the filler (E) is preferred because it has the effect of controlling rheology, that is, increasing viscosity and imparting thixotropy. Examples of the filler (E) include talc, aluminum silicate, fine silica, calcium carbonate, mica, alumina hydrate, zinc dust, carbon black, silicon carbide, fused silica, crystalline silica, alumina, talc, silicon nitride, and aluminum nitride. The content of the filler (E) is not particularly limited as long as it is within a range in which the effects of the present embodiment can be obtained with respect to the entire modified epoxy resin composition of the present embodiment. Usually, it is preferably 90 mass% or less of the modified epoxy resin composition of the present embodiment. By setting the filler content within the above range, the viscosity of the modified epoxy resin composition tends to be sufficiently low and easy to handle.

[0046] (Other hardening components (F)) The modified epoxy resin composition of the present embodiment may further contain another curing component (F). It is preferable to contain the other curing component (F) from the viewpoint of controlling the viscosity, curability and physical properties of the cured product. Examples of the other curing components (F) include unsaturated polyester resins, (meth)acrylate compounds, isocyanates, and vinyl esters. The content of the other curing component (F) is not particularly limited as long as it is within a range in which the effects of the present embodiment can be obtained relative to the entire epoxy resin composition of the present embodiment, but is preferably 5 to 90 mass % of the modified epoxy resin composition of the present embodiment.

[0047] (Additives) The epoxy resin composition of the present embodiment may further contain various additives, such as a flame retardant, a liquid stress agent, a silane coupling agent, a diluent, a leveling agent, a release agent, and a pigment, as necessary. Among these, any suitable one can be selected as appropriate within a range in which the effects of this embodiment can be obtained.

[0048] Examples of the flame retardant include bromine-based flame retardants, phosphorus-based flame retardants, and inorganic flame retardants. Bromine-based flame retardants include tetrabromophenol. Phosphorus-based flame retardants include 9,10-dihydro-9-oxa-10-phosphananthrene-10-oxide. and its epoxy derivatives, triphenylphosphine and its derivatives, phosphate esters, condensed phosphate esters, phosphazene compounds, etc. Nitrogen-based flame retardants include guanidine-based flame retardants, triazine structure-containing phenols, melamine polyphosphate, isocyanuric acid, etc. Inorganic flame retardant compounds include magnesium hydroxide and aluminum hydroxide, with magnesium hydroxide being preferred from the viewpoint of heat resistance. The content of the flame retardant is not particularly limited, but is preferably 5 to 200 mass %, and more preferably 10 to 100 mass %, based on the total amount of the epoxy resin.

[0049] Examples of liquid stress reducing agents include organic rubbers such as polyalkylene glycols and their amine-modified derivatives, polybutadiene and acrylonitrile, silicone rubbers such as dimethylsiloxane, and silicone oils. These may be used alone or in combination of two or more. The content of the liquid stress reducing agent is not particularly limited, but is preferably 5 to 40 mass % and more preferably 10 to 20 mass % relative to the epoxy resin.

[0050] Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N-(2-(vinylbenzylamino)ethyl)3-aminopropyltrimethoxysilane hydrochloride, 3-methacryloxypropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, and 3-chloropropyltrimethoxysilane. Among these, silane coupling agents having a polymerizable functional group are preferred from the viewpoint of adhesive strength.

[0051] Examples of the diluent include a polyfunctional acrylate compound containing an acrylic group and a glycidyl-type reactive diluent containing a monofunctional glycidyl group. These may be used alone or in combination of two or more. The content of the diluent is not particularly limited, but is preferably 1 to 40% by mass, more preferably 5 to 30% by mass, based on the epoxy resin.

[0052] Examples of the leveling agent include silicone-based leveling agents and acrylic-based leveling agents.

[0053] [Cured product] The cured product of the present embodiment is a cured product of the modified epoxy resin composition of the present embodiment described above, and can be obtained by thermally curing the modified epoxy resin composition by a conventionally known method or the like. Specifically, the modified epoxy resin or epoxy resin composition of the present embodiment is thoroughly mixed with a curing agent, and if necessary, a curing accelerator, an inorganic filler, and compounding agents, etc., using an extruder, kneader, rolls, etc. until it becomes uniform, and then molded using a cast or transfer molding machine, injection molding machine, etc., and further heated under conditions of about 80 to 200° C. for about 0.5 to 10 hours to obtain a cured product.

[0054] In addition, a prepreg can be obtained by dissolving the modified epoxy resin composition of the present embodiment in a solvent such as toluene, xylene, acetone, methyl ethyl ketone, or methyl isobutyl ketone, impregnating a substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, or paper, and drying by heating. A cured product can also be obtained by hot press molding the obtained prepreg.

[0055] The modified epoxy resin composition of the present embodiment can be used to form a sheet mold compound, and the resulting sheet mold compound sheet can be used to apply pressure and heat to obtain a cured product. EXAMPLES

[0056] The present embodiment will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples and comparative examples. In the following, unless otherwise specified, "parts" are based on mass.

[0057] ((1) Measurement of α-glycol content) The amount of α-glycol in the modified epoxy resin was determined in accordance with JIS K7146. The amount of α-glycol was measured by decomposing the α-glycol of a sample dissolved in chloroform with ammonium benzyltrimethylperiodate and titrating the remaining periodic acid with an aqueous sodium thiosulfate solution using starch as an indicator. This is called "α-glycol amount 1." Furthermore, the modified epoxy resin was dissolved in methyl isobutyl ketone to a concentration of 30% by mass, and then a 50% aqueous solution of potassium hydroxide in an amount equivalent to 2 of the total chlorine amount measured by the following (2) was added and stirred at 80°C for 30 minutes. After that, the mixture was washed with water, and the solvent was recovered. The modified epoxy resin obtained was used to measure the amount of α-glycol in the same manner. This is called "α-glycol amount 2". The difference between "α-glycol amount 2" and "α-glycol amount 1" was calculated.

[0058] ((2) Total chlorine content) The total chlorine content in the modified epoxy resin was determined in accordance with JIS K7246. The modified epoxy resin was dissolved in diethylene glycol monobutyl ether, and 1N potassium hydroxide-propylene glycol solution was added. The mixture was boiled for 20 minutes, and then potentiometric titration was performed with silver nitrate.

[0059] ((3) Hydrolyzable chlorine content) The amount of hydrolyzable chlorine in the modified epoxy resin was measured by the following method. The modified epoxy resin was dissolved in toluene, and a 0.1N potassium hydroxide-methanol solution was added. The mixture was boiled for 20 minutes, and then potentiometric titration was performed with silver nitrate.

[0060] ((4) Epoxy equivalent) The epoxy equivalent of the epoxy resin was determined in accordance with JIS-K7236. The modified epoxy resin was dissolved in chloroform, and acetic acid and tetraethylammonium bromide acetate solution were added, followed by potentiometric titration with perchloric acid acetate solution at room temperature.

[0061] ((5) Measurement of molecular weight distribution) The molecular weight distribution of the modified epoxy resin was determined by the following method. The modified epoxy resin was dissolved in THF (tetrahydrofuran) and measured using gel permeation chromatography (GPC: manufactured by Tosoh Corporation; product name HLC8320GPC, one column KF-804, one column KF-803, and two columns KF-802). A calibration curve was prepared using polystyrene.

[0062] ((6) Measurement of water content in the system) The water content of the epoxy resin during modification was determined in accordance with JIS K0068. The epoxy resin before the addition of the modifier was sampled, and the moisture content was measured as a blank by dissolving the epoxy resin in dimethylformamide, and the moisture content was measured using a Karl Fischer moisture meter.

[0063] ((7) Softening point) The softening point of the modified epoxy resin was determined according to the ring and ball method of JIS K-7234.

[0064] ((8) Peel strength) The modified epoxy resin compositions shown in Tables 2 and 3 were cured at 180°C for 1 hour in accordance with JIS C6484 (test method for copper-clad laminates for printed wiring boards), to prepare test pieces using 35 μm copper foil, and the shear adhesion was evaluated. Further, a similarly prepared sample was placed in a thermohygrostat at 85° C. and 85% RH for 1000 hours. The sample after the wet heat test was subjected to the same measurements, and the peel strength retention rate was calculated.

[0065] (9) Compressive strength The compressive strength of the modified epoxy resin composition was determined in accordance with JIS K7089. A prepreg with a Vf of 70% was prepared using the modified epoxy resin composition and carbon fiber Torayca cloth CO6142 shown in Tables 2 and 3. The prepreg was then cut into 10 cm x 10 cm pieces, and seven pieces were stacked together to obtain a 40 kgf / cm 2 The CFRP samples were then cured at 180°C for 1 hour under a pressure of 1000 MPa to prepare CFRP samples. The compressive strength and compressive strength after impact were measured using the CFRP samples. Furthermore, samples prepared under the same conditions were placed in a thermohygrostat at 85°C and 85% RH for 1000 hours. The samples after the wet heat test were subjected to the same measurements, and the compressive strength and the retention rate of compressive strength after impact were calculated.

[0066] [Production Example 1] A reactor was charged with 100.0 parts by mass of a bisphenol A type epoxy resin (manufactured by DIC Corporation: product name "Epicron 850") as a raw material glycidyl compound, and 0.40 parts by mass of a 10% by mass solution of tetramethylammonium bromide (a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in methyl ethyl ketone, followed by stirring and heating until the internal temperature reached 140°C. It was confirmed that the water content in the system at this time was 1000 ppm or less. As a raw material isocyanate compound, 12.0 parts by mass of tolylene diisocyanate (TDI, manufactured by Tosoh Corporation: product name "Coronate T80 (trademark)") was added to the reactor over 90 minutes. After the addition was completed, the reaction temperature was kept at 175°C and the mixture was stirred for 8 hours to obtain a modified epoxy resin (A-1). The resulting modified epoxy resin (A-1) had a total chlorine content of 1535 ppm, a hydrolyzable chlorine content of 320 ppm, an epoxy equivalent of 330 g / eq, an α-glycol content 1 of 15 ppm, and an α-glycol content 2 of 24 ppm. The number average molecular weight was 670, the weight average molecular weight was 1520, Mw / Mn was 2.27, and the amount of components with a number average molecular weight of 4000 or more was 10 mass % or less.

[0067] [Production Example 2] Into a reactor, 100.0 parts by mass of bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation: product name "jER806") and 0.40 parts by mass of a 10% by mass solution of 2-phenylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd.: product name "2PZ") in methanol were charged as raw material glycidyl compounds, and the mixture was stirred and heated until the internal temperature reached 90°C. Thereafter, the pressure was reduced for 30 minutes to remove methanol and water from the system. It was confirmed that the water content in the system at this time was 1000 ppm or less. Thereafter, 19.5 parts by mass of naphthalene diisocyanate (NDI manufactured by Covestro: product name "Desmodur 15 (trademark)") was charged into the reactor as a raw material isocyanate compound, and after dissolution, the reaction temperature was raised to 175°C. Thereafter, the internal temperature was kept at 175° C. and the mixture was stirred for 8 hours to obtain a modified epoxy resin (A-2). The resulting modified epoxy resin (A-2) had a total chlorine content of 1420 ppm, a hydrolyzable chlorine content of 60 ppm, an epoxy equivalent of 388 g / eq, an α-glycol content 1 of 20 ppm, and an α-glycol content 2 of 62 ppm. The number average molecular weight was 780, the weight average molecular weight was 1490, Mw / Mn was 1.91, and the amount of components with a number average molecular weight of 4000 or more was 10 mass % or less.

[0068] [Production Example 3] Into a reactor, 100.0 parts by mass of a biphenyl-type epoxy resin (manufactured by Mitsubishi Chemical Corporation: product name "YX4000") as a raw material glycidyl compound and 0.40 parts by mass of a 10% by mass solution of tetramethylammonium chloride (a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in methanol were placed, and the mixture was stirred and heated to an internal temperature of 140°C. Thereafter, the pressure was reduced for 30 minutes to remove methanol and water from the system. It was confirmed that the water content in the system at this time was 1000 ppm or less. Then, tolylene diisocyanate (TDI) was used as the raw isocyanate compound. 14.6 parts by mass of Tosoh Corporation's product name "Coronate T80 (trademark)" was added to the reactor over a period of 3 hours. After the addition was completed, the reaction temperature was kept at 175°C and the mixture was stirred for 8 hours to obtain a modified epoxy resin (A-3). The resulting modified epoxy resin (A-3) had a total chlorine content of 1048 ppm, a hydrolyzable chlorine content of 40 ppm, an epoxy equivalent of 280 g / eq, an α-glycol content of 1 of 6 ppm, and an α-glycol content of 2 of 26 ppm. The resin also had a number average molecular weight of 580, a weight average molecular weight of 1530, an Mw / Mn of 2.63, and a content of components having a number average molecular weight of 4000 or more of 15 mass% or less.

[0069] [Production Example 4] A modified epoxy resin (A-4) was obtained under the same conditions as in Production Example 3, except that the raw glycidyl compound in the reactor was changed to 100.0 parts by mass of epoxy phenol novolac resin (EPN, manufactured by DIC: product name "EPICLON-N740") and the raw isocyanate compound was changed to 4.2 parts by mass of isophorone diisocyanate (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.). The resulting modified epoxy resin (A-4) had a total chlorine content of 1548 ppm, a hydrolyzable chlorine content of 500 ppm, an epoxy equivalent of 220 g / eq, an α-glycol content of 34 ppm, and an α-glycol content of 62 ppm. The resin also had a number average molecular weight of 920, a weight average molecular weight of 3720, an Mw / Mn of 4.04, and a content of components having a number average molecular weight of 4000 or more of 25 mass% or less.

[0070] [Production Example 5] Into the reactor, 100.0 parts by mass of triglycidylaminophenol resin (manufactured by Mitsubishi Chemical Corporation: trade name "jER630") was charged as a raw material glycidyl compound, and the mixture was stirred and heated until the internal temperature reached 110°C. The pressure was then reduced for 30 minutes to remove moisture from the system, and 0.04 parts by mass of diazabicycloundecene (manufactured by San-Apro Co., Ltd.: trade name "DBU") was charged. The mixture was then stirred and mixed. It was confirmed that the water content in the system at this time was 1000 ppm or less. Then, 10.8 parts by mass of hexamethylene diisocyanate (HDI, manufactured by Asahi Kasei Corporation: product name "Duranate M50 (trademark)") as a raw material isocyanate compound was added to the reactor over 60 minutes, and then the reaction temperature was raised to 175° C. The mixture was stirred for 8 hours while maintaining the internal temperature at 175° C., to obtain a modified epoxy resin (A-5). The resulting modified epoxy resin (A-5) had a total chlorine content of 2530 ppm, a hydrolyzable chlorine content of 1050 ppm, an epoxy equivalent of 235 g / eq, an α-glycol content of 1 of 4 ppm, and an α-glycol content of 2 of 12 ppm. The resin also had a number average molecular weight of 2850, a weight average molecular weight of 8230, an Mw / Mn of 2.88, and a content of components having a number average molecular weight of 4000 or more of 42% by mass.

[0071] [Production Example 6] As the epoxy resin, 100.0 parts by mass of bisphenol A type epoxy resin (manufactured by DIC Corporation: product name "Epicron 850") and 0.20 parts by mass of tris(2,6-dimethoxyphenyl)phosphine (a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were charged into a reactor as raw material glycidyl compounds, and the mixture was stirred and heated to an internal temperature of 150°C. At this time, it was confirmed that the water content in the system was 1500 ppm. After further heating for 1 hour, 18.0 parts by mass of tolylene diisocyanate (TDI, manufactured by Tosoh Corporation: product name "Coronate T80 (trademark)") as a raw material isocyanate compound was added to the reactor over a period of 3 hours. After the addition was completed, the reaction temperature was kept at 175° C. and the mixture was stirred for 8 hours to obtain a modified epoxy resin (A-6). The resulting modified epoxy resin (A-6) had a total chlorine content of 1450 ppm, a hydrolyzable chlorine content of 300 ppm, an epoxy equivalent of 380 g / eq, an α-glycol content of 30 ppm, and an α-glycol content of 90 ppm. The resin also had a number average molecular weight of 790, a weight average molecular weight of 2240, an Mw / Mn of 2.84, and a content of components having a number average molecular weight of 4000 or more of 10% by mass or less.

[0072] [Production Example 7] As the epoxy resin, 100.0 parts by mass of bisphenol A type epoxy resin (manufactured by DIC Corporation: product name "Epicron 850") and 0.80 parts by mass of a 10% aqueous potassium hydroxide solution (reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were charged into a reactor as raw material glycidyl compounds, and the mixture was stirred and heated to an internal temperature of 90°C. It was confirmed that the water content in the system at this time was 6000 ppm. After further heating for 1 hour, 18.0 parts by mass of naphthalene diisocyanate (NDI manufactured by Covestro: product name "Desmodur 15 (trademark)") was added as a raw material isocyanate compound to the reactor, and after dissolution, the reaction temperature was raised to 175° C. Thereafter, the internal temperature was kept at 175° C. and the mixture was stirred for 8 hours to obtain a modified epoxy resin (A-7). The resulting modified epoxy resin (A-7) had a total chlorine content of 1320 ppm, a hydrolyzable chlorine content of 290 ppm, an epoxy equivalent of 375 g / eq, an α-glycol content of 1 of 40 ppm, and an α-glycol content of 2 of 120 ppm. The resin also had a number average molecular weight of 780, a weight average molecular weight of 1620, an Mw / Mn of 2.08, and a content of components having a number average molecular weight of 4000 or more of 10% by mass or less.

[0073] [Table 1]

[0074] [Examples 1 to 8] [Comparative Examples 1 to 5] Modified epoxy resin compositions were prepared using the modified epoxy resins (A-1) to (A-7) of Production Examples 1 to 7 described above and the components shown below in the amounts shown in Tables 2 and 3 below. Dicyandiamide: Tokyo Chemical Industry Co., Ltd., reagent Kane Ace MX125: Kaneka Corporation, epoxy resin containing core-shell type rubber particles Omicure 24: Made by CVC Teamoset, urea-based curing accelerator EB220: Aromatic urethane acrylate, manufactured by Daicel Allnex Co., Ltd. Vinylec K: Polyvinyl formal resin manufactured by JNC Corporation 2PI: Tokyo Chemical Industry Co., Ltd., Reagent jER828: Bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation

[0075] [Table 2]

[0076] [Table 3] [Industrial Applicability]

[0077] The modified epoxy resin and modified epoxy resin composition of the present invention have industrial applicability in adhesive applications and fiber-reinforced composite material applications.

Claims

1. A modified epoxy resin having a softening point of 50° C. or higher and a hydrolyzable chlorine content of 2000 ppm or less, the difference in the amount of α-glycol before and after treatment at 80° C. for 30 minutes with an aqueous alkali solution in an amount twice the equivalent of the total chlorine amount in the modified epoxy resin is 50 ppm or less; The compound has the structure represented by the following formula (1) and / or (2): Modified epoxy resin. 【Chemistry 1】 【Chemistry 2】 In formulas (1) and (2), R 1 to R 4 each independently represent a divalent functional group having a substituent. In addition, X and Y each represent a structure containing an epoxy group or an oxazolidone ring.

2. The epoxy equivalent value based on JIS-K7236 is 200 (g / eq) or more and 1000 (g / eq) or less. The modified epoxy resin according to claim 1.

3. Weight-average molecular weight distribution and number-average molecular weight distribution in terms of polystyrene by gel permeation chromatography. The molecular weight ratio (Mw / Mn) is 4.0 or less, and the amount of components having a number average molecular weight of 4,000 or more is 40 % by mass or less, The modified epoxy resin according to claim 1 or 2.

4. The modified epoxy resin (A) according to any one of claims 1 to 3, an epoxy resin (B) other than the modified epoxy resin (A); A curing agent (C); A modified epoxy resin composition comprising:

5. The modified epoxy resin composition according to claim 4, further comprising a plasticizer (D).

6. The content of the modified epoxy resin (A) is The modified epoxy resin (A) plus the epoxy resin (B) other than (A) was taken as 100 parts by mass. When the amount is 10 to 95 parts by mass, The modified epoxy resin composition according to claim 4 or 5.

7. A cured product of the modified epoxy resin composition according to any one of claims 4 to 6.

Images