JP5263120B2 - Fiber reinforced composite material - Google Patents

Description

The present invention relates to an epoxy resin composition, and a fiber-reinforced composite material comprising a cured product thereof and reinforcing fibers.

  Fiber reinforced composite materials composed of reinforced fibers and matrix resins can be designed using the advantages of reinforced fibers and matrix resins, so the applications have been expanded widely in aerospace, sports, general industrial fields, etc. Yes.

  As the reinforcing fiber, glass fiber, aramid fiber, carbon fiber, boron fiber or the like is used. As the matrix resin, either a thermosetting resin or a thermoplastic resin is used, but a thermosetting resin that can be easily impregnated into the reinforcing fiber is often used. And as a thermosetting resin, an epoxy resin, unsaturated polyester resin, vinyl ester resin, phenol resin, maleimide resin, cyanate resin, etc. are used in many cases.

  For the production of the fiber reinforced composite material, methods such as a prepreg method, a hand lay-up method, a filament winding method, a pultrusion (pulling molding) method, an RTM (Resin Transfer Molding) method, and a press molding method are applied. Among these, in the hand lay-up method, filament winding method, pultrusion molding method, RTM method, and press molding method, the fibers need to be impregnated quickly, so that the viscosity needs to be sufficiently low.

  Among them, the pultrusion molding method is such that a reinforcing fiber is continuously passed through an impregnation tank filled with a liquid thermosetting resin composition, impregnated with the thermosetting resin composition, and pulled through a squeeze die and a heating die. This is a molding method in which the fiber-reinforced composite material can be continuously molded while being drawn and cured continuously. Because of this advantage, pultrusion molding is performed in the production of reinforced fiber plastics (FRP) such as fishing rods, rods, pipes, sheets, antennas, and building structures. Among them, when used for a fishing rod tip (for example, Patent Document 1), a solid pultruded product is thinner than a hollow one, can be reduced in weight, and can further produce a high strength product. Have advantages.

  In the pultrusion molding, the resin composition needs to have a sufficiently low viscosity so that the reinforcing fibers can be quickly impregnated in the impregnation tank, and the stability of the viscosity is important from the viewpoint of long-term continuous productivity. In addition, in order to enable high-speed production, it is also necessary to achieve both high curability and rapid curing of the resin in the mold.

  As a resin composition used for pultrusion molding, a composition composed of an epoxy resin, an acid anhydride, and imidazole is known (for example, Patent Document 2). However, since the viscosity of the epoxy resin to be used is high, the viscosity of the resin composition is high and the impregnation property to the reinforcing fiber is poor, so that mechanical properties are hardly expressed, and the surface quality of the molded product is poor. There were drawbacks.

  In order to solve this problem, an example in which a low-viscosity epoxy resin is used for pultrusion molding is also known (for example, Patent Document 3). In this example, since the epoxy resin to be used has a low viscosity but is multifunctional, there is a problem that the reactivity is high, the viscosity stability is lowered, and the continuous productivity is lowered.

  In order to solve this problem, a pultrusion resin composition having both viscosity stability and fast curability is also known (for example, Patent Document 4). However, although the molded product obtained in this example is suitable for applications requiring strength and heat resistance such as building materials, it is not suitable for applications requiring flexibility such as fishing rods.

  For applications requiring such flexibility, it is required that the amount of bending deflection of the molded product is large. In particular, when used on a fishing rod tip, if the reel thread is wound more than necessary, a mechanism such as floating that is wound up is caught by the tip guide, and if the thread is wound too much, the thin tip will bend and eventually endure the bending. In order to prevent the trouble that the tip is damaged when it is no longer possible, it is necessary to have the characteristic that it does not break even if the bending curvature is increased to the limit.

  In order to increase the amount of bending and bending of the molded product and increase the amount of bending of the tip, one measure is to increase the elongation and toughness while maintaining the strength and elastic modulus of the epoxy resin. As a technique for increasing the elongation and toughness, addition of a modifier such as a rubber component or a thermoplastic resin or addition of a high molecular weight epoxy resin to the epoxy resin composition is known. However, when these modifiers and high molecular weight epoxy resins are added, the viscosity of the resin composition may increase, and in addition, the elastic modulus of the cured resin may decrease. For example, as a resin composition for a prepreg, an improvement in elongation by adding a high molecular weight epoxy resin (for example, Patent Document 5) and an improvement in toughness by adding a thermoplastic resin (for example, Patent Document 6) are effective. However, since all of them have high viscosity, there is a problem that it is difficult to use for pultrusion molding. Thus, it is not easy to maintain a viscosity characteristic for pultrusion molding and to obtain a molded article having both flexibility and strength, such as fishing rod use, and a product excellent in these characteristics is awaited. .

On the other hand, in the pultrusion molding, an internal mold release agent may be added to ensure moldability (for example, Patent Documents 2, 4, and 7). The internal mold release agent generally expresses mold release properties between the molded product and the mold and improves continuous productivity, and is added at most by 0.1 to 8 parts by mass with respect to 100 parts by mass of the epoxy resin. However, there is no suggestion that this increases the amount of bending deflection of the molded product, and also increases the amount of bending of the tip when the tip of the fishing rod is drawn out.

JP-A 63-269939 JP 2005-343112 A Japanese Patent No. 5-117412 JP 2008-38082 A JP 2000-336191 A JP 2006-291092 A JP-A-11-236432

  The problem of the present invention is that the epoxy resin composition suitably used in producing a fiber-reinforced composite material by pultrusion has a viscosity that can be sufficiently impregnated in the pultrusion, and has excellent rapid curability while being drawn. It is an object of the present invention to provide a pultruded molded product and a fishing rod tip having a large amount of bending when a pultruded molded product and a fishing rod tip having a small change in viscosity at the time of molding and excellent in bending deflection and strength.

As a result of various studies to solve the above problems, the present inventor has found a cured product obtained by curing the epoxy resin composition shown below and a fiber-reinforced composite material including reinforcing fibers .

That is,
(1) (a) epoxy resin, (b) acid anhydride, (c) imidazole derivative, and (d) a cured product obtained by curing an epoxy resin composition , and a fiber comprising reinforcing fiber a reinforced composite material, (a) an epoxy resin, bifunctional epoxy resin viscosity is less than 3000 mPa · s at 25 ° C., an epoxy resin containing 60 to 100 parts by mass in 100 parts by weight of total epoxy resin, ( d) A fiber-reinforced composite material, wherein the internal mold release agent is contained in an amount of 9 to 15 parts by mass with respect to 100 parts by mass of the total epoxy resin.

(2) The bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less is selected from the group consisting of bisphenol F type epoxy resin, diglycidyl aniline, diglycidyl o-toluidine, resorcinol type epoxy resin, and alicyclic epoxy resin. The fiber-reinforced composite material according to (1), comprising at least one selected.

(3) The fiber-reinforced composite material according to (1) or (2), wherein (d) the internal release agent is a fatty acid ester release agent that is liquid at 25 ° C.

( 4 ) The fiber-reinforced composite material according to any one of (1) to (3), wherein the reinforcing fiber is a carbon fiber.

The epoxy resin composition used in the present invention (hereinafter sometimes referred to as “the epoxy resin composition of the present invention”) is suitable for a molding method that requires a low-viscosity epoxy resin composition, particularly a pultrusion molding method. It has a viscosity that can be sufficiently impregnated in the pultrusion molding method, has excellent rapid curability, has a small viscosity change during pultrusion molding, and is excellent in continuous productivity.

  In addition, by adding a much larger amount of the internal mold release agent contained in the epoxy resin composition of the present invention than the amount usually added, a molded product excellent in bending deflection and strength, particularly a fishing rod. A molded product with a large amount of bending when used as a tip, a fishing rod tip can be provided.

The epoxy resin composition of the present invention is an epoxy resin composition comprising (a) an epoxy resin, (b) an acid anhydride, (c) an imidazole derivative, and (d) an internal mold release agent, wherein (a) the epoxy resin Is an epoxy resin containing 60 to 100 parts by mass of a bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less in 100 parts by mass of all epoxy resins, and (d) the internal mold release agent is 100 It is an epoxy resin composition that is contained in an amount of 9 to 15 parts by mass with respect to parts by mass, and is suitably used for producing a fiber-reinforced composite material by pultrusion molding.

  The (a) epoxy resin used in the present invention is an epoxy resin containing a bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less in a range of 60 parts by mass to 100 parts by mass in 100 parts by mass of all epoxy resins. The bifunctional mentioned here refers to a substance having two epoxy groups in the molecule. Moreover, it is preferable that 70 mass parts or more is contained in 100 mass parts of all the epoxy resins from a viewpoint of the improvement of pultrusion moldability, the bifunctional epoxy resin whose viscosity in 25 degreeC is 3000 mPa * s or less.

  A bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less preferably has a viscosity at 25 ° C. of 5 mPa · s or more and 3000 mPa · s or less. More preferably, they are 5 mPa * s or more and 2500 mPa * s or less. When it is less than 5 mPa · s, when the epoxy resin composition is finally combined with (b) acid anhydride or (c) imidazole derivative, the initial viscosity is too low. As a result, the amount of adhesion of the surface may deteriorate and the surface quality and the like may deteriorate. When the viscosity exceeds 3000 mPa · s, the initial viscosity becomes high when the epoxy resin composition is finally obtained, so that the resin is not impregnated in the reinforcing fiber bundle at the time of pultrusion and may cause voids. The viscosity here is determined by a measurement method using a cone-plate type rotational viscometer in ISO2884-1 (1999) at 25 ° C. Moreover, initial viscosity refers to the viscosity immediately after mixing all the components with the ratio described in the preparation table.

  As the bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less, bisphenol F type epoxy, diglycidyl aniline, diglycidyl o-toluidine, resorcinol type epoxy resin, and alicyclic epoxy are preferably used. Among these, bisphenol F type epoxy resin, diglycidyl aniline, and diglycidyl o-toluidine are preferably used from the viewpoint of mechanical properties. As a commercial product of a bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less, as a bisphenol F type epoxy resin, “jER (registered trademark)” 806 (viscosity: 2000 mPa · s), “jER (registered trademark)” "1750 (viscosity: 1300 mPa · s) (above, manufactured by Japan Epoxy Resin Co., Ltd.), GY285 (viscosity: 2500 mPa · s), PY306 (viscosity: 1400 mPa · s) (above, manufactured by Huntsman Advanced Materials), etc. It is done.

  As the alicyclic epoxy, (3 ′, 4′-epoxycyclohexane) methyl 3,4-epoxycyclohexanecarboxylate includes “Celoxide (registered trademark)” 2021P (viscosity: 250 mPa · s, Daicel Chemical Industries, Ltd.) And CY179 (viscosity: 400 mPa · s, manufactured by Huntsman Advanced Materials Co., Ltd.). (3 ′, 4′-epoxycyclohexane) octyl 3,4-epoxycyclohexanecarboxylate includes “Celoxide (registered trademark)” 2081 (viscosity: 100 mPa · s, manufactured by Daicel Chemical Industries, Ltd.), 1-methyl- As 4- (2-methyloxiranyl) -7-oxabicyclo [4.1.0] heptane, “Celoxide (registered trademark)” 3000 (viscosity: 20 mPa · s, manufactured by Daicel Chemical Industries, Ltd.), Etc.

  As a commercial item of diglycidyl aniline, GAN (viscosity: 120 mPa · s, manufactured by Nippon Kayaku Co., Ltd.) can be mentioned.

  A commercially available product of diglycidyl o-toluidine is GOT (viscosity: 70 mPa · s, manufactured by Nippon Kayaku Co., Ltd.).

  As commercial products of resorcinol type epoxy resin, “ERISYS (registered trademark)” RDGE / H (viscosity: 250 mPa · s, manufactured by PTI Japan), “Denacol (registered trademark)” Ex-203 (manufactured by Nagase ChemteX Corporation) ) And the like.

  In addition, (a) the epoxy resin may contain an epoxy resin other than a bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less in a range of 0 to 40 parts by mass in 100 parts by mass of the total epoxy resin. it can. In this case, an epoxy resin other than a bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less can be blended within a viscosity range used for pultrusion molding. In the viscosity range used for pultrusion, specifically, when the epoxy resin composition used for pultrusion is used, the viscosity is preferably 50 to 2000 mPa · s, and acid anhydrides, It can be prepared in this region by addition / mixing of imidazole derivatives. Examples of the epoxy resin other than the bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less include, for example, tetraglycidyldiaminodiphenylmethane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, triglycidyl- Examples include glycidylamine type epoxy such as p-aminophenol and triglycidyl-m-aminophenol, glycidyl phthalate ester, glycidyl ester type epoxy such as glycidyl hydrophthalate, bisphenol S type epoxy resin, and bisphenol A type epoxy resin. It is done. When more heat resistance is required, it is preferable to add a glycidylamine type epoxy resin.

  The present invention includes (b) an acid anhydride. Although there is no restriction | limiting in particular as an acid anhydride, Since the viscosity of the resin composition obtained by mixing with (a) epoxy resin and (c) imidazole derivative becomes low, what is liquid at 25 degreeC is preferable, especially The viscosity at 25 ° C. is preferably 20 mPa · s or more and 1000 mPa · s or less. More preferably, it is 20 mPa · s or more and 200 mPa · s or less, and most preferably 20 mPa · s or more and 150 mPa · s or less. When the viscosity is less than 20 mPa · s, when a low viscosity epoxy resin of 50 mPa · s or less is used, the viscosity of the resin composition becomes too low, and the amount of the resin adhering to the reinforcing fiber may be reduced at the time of pultrusion molding. is there. Specific examples include tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl nadic anhydride, trialkyltetrahydrophthalic anhydride, dodecyl succinic anhydride, and the like. In particular, hexahydrophthalic anhydride and methylhexahydrophthalic anhydride are preferred because of low viscosity of about 40 to 70 mPa · s and excellent heat resistance of the resulting cured product. Moreover, you may mix and use 2 or more types as needed.

  Examples of commercially available methyltetrahydrophthalic anhydride include “Licacid (registered trademark)” MT500 (viscosity: 50 mPa · s, manufactured by Shin Nippon Rika Co., Ltd.).

  Examples of commercially available hexahydrophthalic anhydride include “Licacid (registered trademark)” HH (melting point: 34 ° C., manufactured by Shin Nippon Rika Co., Ltd.).

  Commercial products of methylhexahydrophthalic anhydride include “EPICLON (registered trademark)” B-570 (viscosity: 40 mPa · s), “EPICLON (registered trademark)” B-650 (viscosity: 65 mPa · s) (above DIC) Etc.).

  As a commercial product of a mixture of hexahydrophthalic anhydride and methylhexahydrophthalic acid, “Rikacid (registered trademark)” MH700 (viscosity: 60 mPa · s) blended with methylhexahydrophthalic anhydride: hexahydrophthalic anhydride = 70: 30. s, Shin Nippon Rika Co., Ltd.) and the like.

  Examples of commercially available methyl nadic acid anhydride include “Kayahard (registered trademark)” MCD (viscosity: 200 mPa · s, manufactured by Nippon Kayaku Co., Ltd.). Examples of commercially available products of trialkyltetrahydrophthalic anhydride include “jER Cure (registered trademark)” YH-306 (viscosity: 130 mPa · s, manufactured by Japan Epoxy Resin Co., Ltd.).

  (B) Since the acid anhydride has a good balance between the initial viscosity of the epoxy resin composition and the obtained heat resistance, (a) the active hydrogen equivalent of the acid anhydride with respect to 1 equivalent of epoxy of the epoxy group contained in the epoxy resin The blending amount is preferably determined so that (the molecular weight of the acid anhydride divided by the number of reaction points) is in the range of 0.5 to 1.5 equivalents. More preferably, it is 0.7-1.2 equivalent. When the amount is less than 0.5 equivalent, the initial viscosity may be increased and curing may be insufficient. When the amount is more than 1.5 equivalent, the mechanical properties of the cured product may be deteriorated.

  The (c) imidazole derivative used in the present invention means a compound having an imidazole ring in the molecule. Specifically, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-isobutyl-2-methylimidazole, 1-aminoethyl- Examples include 2-methylimidazole, but are not limited thereto. Among imidazole derivatives, imidazole derivatives having a substituent at the 1-position are excellent in viscosity stability and are preferably used. Among them, in order not to increase the viscosity of the composition more than necessary, an imidazole derivative having a melting point of 50 ° C. or lower, more preferably 25 ° C. or lower and liquid at 25 ° C. is used. These imidazole derivatives may be used alone or in combination of two or more.

  (C) Specific commercial products of imidazole derivatives having a substituent at the 1-position included in the imidazole derivatives are listed. As commercial products of 1,2-dimethylimidazole, “Curazole (registered trademark)” 1,2DMZ ( Melting point: 35 ° C., manufactured by Shikoku Kasei Co., Ltd.).

  Examples of commercially available 1-benzyl-2-phenylimidazole include “Curazole (registered trademark)” 1B2PZ (melting point: 40 ° C., manufactured by Shikoku Kasei Co., Ltd.).

  Examples of commercially available 1-benzyl-2-methylimidazole include “jER Cure (registered trademark)” BMI12 (viscosity: 2300 mPa · s, manufactured by Japan Epoxy Resins Co., Ltd.).

  As a commercial item of 1-cyanoethyl-2-methylimidazole, “Curazole (registered trademark)” 2MZ-CN (melting point: 53 ° C., manufactured by Shikoku Kasei Co., Ltd.) and the like can be mentioned.

  Examples of commercially available 1-isobutyl-2-methylimidazole include “jER Cure (registered trademark)” IBMI12 (viscosity: 800 mPa · s, manufactured by Japan Epoxy Resins Co., Ltd.).

  (C) As the imidazole derivative, an imidazole derivative having no substituent at the 1-position of the imidazole ring can be used as long as it does not adversely affect the viscosity stability. Specific commercial products of imidazole derivatives that do not have a substituent at the 1-position of the imidazole ring are listed as the commercially available products of 2-methylimidazole, such as “Cureazole (registered trademark)” 2MZ (manufactured by Shikoku Kasei Co., Ltd.), etc. Is mentioned.

  Examples of 2-ethyl-4-methylimidazole include “Cureazole (registered trademark)” 2E4MZ (manufactured by Shikoku Kasei Co., Ltd.), “jER Cure (registered trademark)” EMI24 (manufactured by Japan Epoxy Resin Co., Ltd.), and the like.

  (C) It is preferable that an imidazole derivative is 0.1-5 mass parts with respect to 100 mass parts of all the epoxy resins. If it is less than 0.1 part by mass, the curing rate of the resin composition is slow and may not be used for high-speed molding. On the other hand, when the amount is more than 5 parts by mass, the viscosity increase of the resin composition is large, and stable production in continuous production may not be possible. In particular, the amount is preferably 0.5 to 4 parts by mass.

  (D) Internal mold release agents used in the present invention include metal waxes, polyethylene waxes, plant waxes such as carbana wax, fatty acid ester release agents, silicone oils, animal waxes, fluorine-based nonionic interfaces. An activator and the like can be mentioned, but from the viewpoint of releasability, viscosity, and affinity with an epoxy resin, a fatty acid ester release agent that is liquid at 25 ° C. is preferable. Due to the liquid state, even a low viscosity composition can be mixed uniformly. Further, by mixing the internal mold release agent in the resin, the mold release property between the mold and the molded product is improved, and the drawability is improved. As a result, the surface quality of the molded product and the fiber orientation are improved, so that the mechanical properties such as the bending deflection amount and strength of the molded product are improved. Furthermore, by mixing the internal mold release agent in the resin, the adhesiveness between the resin and the reinforcing fiber is lowered, and the amount of bending deflection of the molded product is improved by appropriately adjusting.

(D) internal mold release agent, it is necessary that 9 is 15 parts by weight per 100 parts by weight total epoxy resin. If the amount is less than 9 parts by mass, most of the internal mold release agent bleeds out to the resin surface, and the amount remaining in the resin is small. The amount of bending deflection may not be obtained. When the amount is 9 to 15 parts by mass, the amount of the internal mold release agent remaining inside the resin is appropriate, and surprisingly the amount of bending of the molded product is improved. On the other hand, when it is added in an amount of more than 15 parts by mass, an appropriate amount or more of the release agent remains in the resin, the adhesiveness between the resin and the reinforcing fiber is excessively lowered, and an excessive internal release agent is a crosslinked structure of the resin. It is thought that the formation is hindered and the elongation and strength of the resin cured product are reduced.As a result, the bending bending amount of the molded product is decreased, the heat resistance of the resin cured product is decreased, and the curing rate of the resin composition is decreased. And may increase the viscosity of the resin composition.

  Such an internal mold release agent that is liquid at 25 ° C. is not particularly limited as long as it does not phase separate from the epoxy resin composition and does not evaporate or decompose at the mold temperature. Especially, in order to suppress the influence on the viscosity of a resin composition, the viscosity of the internal mold release agent which is liquid at 25 ° C. is preferably 50 mPa · s or more and 1000 mPa · s or less.

  Specific commercial products include a mixture of an organic acid derivative, a glyceride and a synthetic resin, MOLD WIZ INT-1846 (viscosity: 425 mPa · s), MOLD WIZ INT-1836, MOLD WIZ INT-1850 (viscosity: 350 mPa · s). ), MOLD WIZ INT-1854 (viscosity: 500 mPa · s) (above AXEL PLASTICS RESEARCH LABORATORIES INC.) And the like.

  The epoxy resin composition of the present invention is obtained by stirring and mixing (a) an epoxy resin, (b) an acid anhydride, (c) an imidazole derivative, and (d) an internal mold release agent with a stirring rod or the like. . Although heating and pressurization may be performed as necessary, long-time heating is not preferable because it increases the viscosity of the resin composition. It is preferable that the mixed epoxy resin composition is uniformly dissolved. Even if some of them are solid or liquid, they form a separated phase, which is not preferable because it may cause local non-uniformity of components in the impregnation process. In addition, (d) the internal mold release agent may be added at any stage of the mixing process, but in order to uniformly disperse, before mixing (b) the acid anhydride and (c) the imidazole derivative, ( a) It is preferable to add to the epoxy resin, and sufficiently stir and disperse.

  The initial viscosity at 25 ° C. immediately after mixing of the epoxy resin composition of the present invention is preferably 50 to 2000 mPa · s, more preferably 100 to 1000 mPa · s, in order to sufficiently impregnate the reinforcing fibers. If it is less than 50 mPa · s, the amount of resin impregnated into the reinforcing fibers may be reduced. On the other hand, if the viscosity is higher than 2000 mPa · s, it may be difficult to penetrate into the reinforcing fiber, resulting in insufficient impregnation and voids. Furthermore, in order to maintain productivity in continuous molding, the viscosity at 25 ° C. after leaving the epoxy resin composition at 25 ° C. for 8 hours is preferably 1.0 to 3.5 times the initial viscosity. . More preferably, it is 1.0 to 3.0 times. Thickening ratio is greatly affected by curing agent and curing accelerator, especially imidazole type and blending amount. If the thickening ratio is large, the thickening ratio can be reduced by changing the imidazole type or reducing the blending amount. Is possible.

  Moreover, in order to achieve high-speed molding, it is preferable that the gel time at 190 ° C. of the epoxy resin composition is within 60 seconds. More preferably, it is within 30 seconds. The gel time referred to here is a time when the torque exceeds 0.001 N · m after the start of measurement using a curast meter device. Gel time is greatly influenced by the type and amount of curing agent and curing accelerator, especially imidazole. If the curability is insufficient, the gel time can be shortened by changing the type of imidazole or increasing the amount. .

  As the reinforcing fiber used in the present invention, glass fiber, aramid fiber, carbon fiber, boron fiber and the like are preferable, but it is preferable to use carbon fiber because it is particularly excellent in strength. The tensile modulus of carbon fiber is preferably 150 to 500 GPa for fishing rod use. The tensile elastic modulus of carbon fiber refers to the strand elastic modulus measured according to JIS R 7601 (1986).

  Moreover, the cross-sectional shape of the single fiber of carbon fiber is not particularly limited, but is preferably substantially circular. Here, the fact that the cross-sectional shape of the single fiber is substantially a perfect circle means that the ratio R / r between the radius R of the circle circumscribing the cross-sectional shape of the single fiber and the radius r of the inscribed circle is 1.0 to 1.1, preferably in the range of 1.0 to 1.05. When the cross-sectional shape of the single fiber is a perfect circle, the strength of the single fiber breaks due to abrasion between the single yarns or bundles of the carbon fiber at the time of pultrusion, reduction in strength, fluff generation, yarn breakage, etc. Trouble is unlikely to occur. Moreover, when the cross-sectional shape of the single fiber is an ellipse, an egg, a bean, or a three-leaf, the mechanical properties of the resulting composite material may be deteriorated. Examples of the carbon fiber having a perfect circular cross section include “Torayca (registered trademark)” T700S and “Torayca (registered trademark)” M30S.

Further, 0.01 to 5% by mass of a component having at least one functional group selected from an epoxy group, a hydroxyl group, an acrylate group, a methacrylate group, an amide group, a carboxyl group and a carboxylic acid anhydride as a sizing agent is attached to the carbon fiber. The resulting product is excellent in scratching during production and affinity with the epoxy resin. In particular, those containing a component having an epoxy group or a hydroxyl group are preferred as the sizing agent. The amount of the sizing agent attached to the carbon fiber was determined by weighing the carbon fiber (W1) and then leaving it in an electric furnace set at a temperature of 450 ° C. for 15 minutes in a nitrogen stream of 50 liters / minute. Thermally decompose. Then, the carbon fiber after being transferred to a container in a dry nitrogen stream at 20 liters / minute and cooled for 15 minutes is weighed (W2), and the sizing agent adhesion amount is determined by the following equation.
Sizing adhesion amount (%) = [W1-W2] / W1 × 100.

  As the carbon fiber used in the present invention, one having 1000 to 200,000 filaments is preferably used. If the number is less than 1,000, the number of carbon fiber bobbins required to obtain a predetermined width and thickness is increased, which makes the operation complicated, and if it is 200,000 or more, the resin is not contained in the carbon fiber bundle. It may become difficult to impregnate and cause voids.

  A method for producing a pultruded product obtained using the epoxy resin composition of the present invention will be described.

  In the present invention, a general pultrusion molding method is performed using the epoxy resin composition, and the pultrusion molded product can be obtained by being heat-cured in parallel with the pultrusion molding or after the pultrusion molding. As a general pultrusion molding method, the reinforcing fiber is continuously passed through an impregnation tank of an epoxy resin composition, and the epoxy resin composition is cured while being continuously pultruded by a tension machine through a squeeze die and a heating mold. . Further, it is completely cured in an after cure oven. The above only shows an example of the pultrusion method, and is not limited.

  The impregnation tank is preferably maintained at 10 to 40 ° C. More preferably, it is 20-30 degreeC. When the temperature of the impregnation tank is 40 ° C. or higher, the viscosity stability of the epoxy resin composition may be deteriorated. Further, when the temperature of the impregnation tank is 10 ° C. or less, the impregnation of the fibers may be deteriorated.

  The temperature of the mold is preferably 100 to 250 ° C. More preferably, it is 120-220 degreeC. When the temperature is 100 ° C. or lower, poor curing in the mold may occur, and when the temperature is 250 ° C. or higher, the runaway reaction of the epoxy resin composition may occur.

  The residence time in the mold is preferably 30 seconds to 5 minutes. If the residence time is 30 seconds or less, curing in the mold is insufficient and the appearance may be deteriorated. If it is 5 minutes or longer, it may be completely cured in the mold and may not be pulled out.

  After-curing may be performed to increase the heat resistance or complete the reaction of the epoxy group. After-curing, after passing through the mold and before product recovery, after-curing oven may be installed and cured online, or after recovery, it may be cured in the oven. The after-curing temperature is preferably 100 to 220 ° C. from the viewpoint of heat resistance and physical properties. More preferably, it is 110-200 degreeC. If it is 100 ° C. or lower, the glass transition temperature of the resin is not exceeded, so that the reaction may not proceed easily. On the other hand, if it is 220 ° C. or higher, it may be deformed or decomposed by heat. The after-curing time is preferably 1 minute to 1 hour, although it depends on the curing temperature. A cure shorter than 1 minute may be too short to complete the reaction. If it is longer than 1 hour, for example, when it is used online, there is a concern that the productivity is too long.

  The volume content (Vf) of the carbon fiber of the pultruded product of the present invention is preferably 40 to 75% in order to sufficiently draw out features that are lightweight and excellent in flexibility and strength. If it is 40% or less, the fiber is difficult to uniformly disperse in the mold and is likely to bend or warp, so that the strength may decrease or the tip may have different flexibility depending on the direction of bending. There is. If it is 75% or more, the rigidity of the molded product becomes too high, and the flexibility may be insufficient. Here, the Vf of the pultruded product can be calculated from the weight content (Wf) and the specific gravity of the carbon fiber and the resin. Wf can be determined by measuring the weight before and after combustion based on the combustion method described in JIS K7075 (1991).

  When the pultruded product obtained by using the epoxy resin composition of the present invention is used as a tip of a fishing rod, a 500 to 1000 mm rod-shaped pultruded product is prepared using a circular mold having a diameter of 2 to 6 mm, and the periphery is polished. By applying a taper, it can be used as a tip. The flexibility of a round bar-shaped pultruded product can be known from the amount of bending deflection in a three-point bending test of the pultruded product. The amount of bending deflection is the amount of crosshead movement when a pultruded product is broken when the pultruded product is subjected to three-point bending according to JIS K7074 (1988). The amount of bending of the tip after taper processing can be evaluated by bending the opposite end with the end portion fixed, and increasing the bending curvature until it breaks.

  EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited to these Examples. In addition, the unit of the content rate of the epoxy resin composition in Tables 1 and 2 means “parts by mass” unless otherwise specified, and (b) the acid anhydride is based on the average epoxy group amount of the epoxy resin used. (B) The ratio (eq.) Of the active hydrogen equivalent of the acid anhydride.

(Resin raw material)
Epoxy resin “jER (registered trademark)” 806 (bisphenol F type epoxy resin, viscosity: 2000 mPa · s, manufactured by Japan Epoxy Resins Co., Ltd.)
GAN (diglycidyl aniline, viscosity: 120 mPa · s, manufactured by Nippon Kayaku Co., Ltd.)
"Epototo (registered trademark)" YD128 (bisphenol A type epoxy resin, viscosity: 13500 mPa · s, manufactured by Tohto Kasei Co., Ltd.)
“Sumiepoxy (registered trademark)” ELM434 (tetraglycidyldiaminodiphenylmethane, viscosity: 100,000 mPa · s, manufactured by Sumitomo Chemical Co., Ltd.).

Acid anhydride “Licacid (registered trademark)” MH700 (Methylhexahydrophthalic anhydride / hexahydrophthalic anhydride, 70/30 mixture, viscosity: 60 mPa · s, manufactured by Shin Nippon Rika Co., Ltd.)
Imidazole derivative “jER Cure (registered trademark)” BMI12 (1-benzyl-2-methylimidazole, viscosity: 2300 mPa · s, manufactured by Japan Epoxy Resins Co., Ltd.).

(Internal release agent)
“MOLD WIZ (registered trademark)” INT 1846 (viscosity: 425 mPa · s, manufactured by AXEL PLASTICS RESEARCH LABORATORIES INC.).

(Reinforced fiber)
"Torayca (registered trademark)" T700S-12K-50C (carbon fiber, 12,000 filaments, manufactured by Toray Industries, Inc.).

(1) Preparation of Resin Composition According to the blending ratios shown in Tables 1 and 2, epoxy resin, acid anhydride, imidazole derivative and internal mold release agent were mixed at 25 ° C. to obtain a resin composition.

(2) Viscosity measurement of resin composition Immediately after adjusting the epoxy resin composition according to the measurement method using a cone-plate type rotational viscometer in ISO 2884-1 (1999) and after adjustment in a thermostatic device at 25 ° C The viscosities left for 8 hours were each measured at 25 ° C. As the apparatus, TVE-30H type manufactured by Tokimec Co., Ltd. was used. Here, the rotor was 1 ° 34 ′ × R24, and the sample amount was 1 cm ³ .

(3) Gel time measurement of resin composition The gel time immediately after adjusting an epoxy resin composition was measured at 190 degreeC. The apparatus used was a curast meter type V manufactured by Orientec Co., Ltd. The sample amount was 2 cm ³ . The time when the torque exceeded 0.001 N · m after the start of measurement was defined as the gel time.

(4) Production of pultruded product The resin compositions of Examples 1 to 4 and Comparative Examples 1 to 6 were retained in a raw material tank at 25 ° C. for 2 hours. The carbon fiber is passed through the raw material tank containing the resin composition so that the number of filaments is 48,000, impregnated with the resin, then inserted into a circular mold, and heated and cured at 190 ° C. for 1.5 minutes. After-curing at 150 ° C. for 4 minutes, a carbon fiber reinforced composite material having a diameter of 2 mm and a Vf of about 55% was obtained.

(5) 0 ° bending test of pultruded product The carbon fiber reinforced composite material produced by the method of (4) above was cut into a length of 100 mm and the test piece was obtained. Using this test piece, three-point bending was performed according to JIS K7074 (1988), and the bending deflection amount and strength at break were measured. An Instron 5565 type was used as the apparatus, and the crosshead speed was 5 mm / min, the span length was 80 mm, the indenter radius was 5 mm, and the fulcrum radius was 2 mm. Here, the amount of bending deflection is the amount of movement of the crosshead at the time of fracture when performing three-point bending.

(6) Measurement of bending amount of fishing rod tip The carbon fiber reinforced composite material produced by the method of (4) above is cut to a length of 550 mm with the fiber direction as the length direction, the original side is 1.9 mm in diameter, and the tip A taper was applied by a centerless polishing process so that the side had a diameter of 0.8 mm to obtain a fishing rod tip. With the original side of the tip of the fishing rod fixed on the scale, the front side is rounded and brought into contact with the scale, and the tip of the contact is moved along the scale (approximately 5 mm / s) to increase the bending curvature. The amount of movement until breakage was measured, and the amount of bending was determined.

As shown in Examples 1 to 7 shown in Table 1, a bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less, 60 to 100 parts by mass in 100 parts by mass of all epoxy resins, and an internal release agent by including 9-15 parts by weight per 100 parts by weight total epoxy resin, good results were obtained. In particular, Examples 1 to 6 containing a bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less in an amount of 70 parts by mass or more in 100 parts by mass of all epoxy resins were better.

From Comparative Examples 1 to 6 in Table 2, when the internal mold release agent is less than 9 parts by mass or more than 15 parts by mass with respect to 100 parts by mass of the total epoxy resin, the pultruded molded product 0 ° bending deflection or fishing rod tip bend The physical properties of the pultruded product such as the amount, the resin viscosity increase rate, and the gel time are inferior to those of the examples. Further, as shown in Comparative Examples 7 and 8, when the bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less is less than 60 parts by mass in 100 parts by mass of the total epoxy resin, the viscosity is higher than that of the Examples. Therefore, the pultrusion property and the physical properties of the pultrusion product are inferior.

  The epoxy resin composition for fiber-reinforced composite material of the present invention can provide a molded article excellent in bending deflection in sports use, general industrial use, and aircraft use. Especially in the pultrusion method, it is a viscosity that can be sufficiently impregnated, and since it has excellent viscosity stability and fast curability, it can be suitably used in pultrusion molding, and can provide a molded product with excellent bending deflection and strength, It is possible to provide a pultruded product suitable for applications such as a fishing rod tip.

Claims (4)

(A) epoxy resin, (b) acid anhydride, (c) imidazole derivative, and (d) a cured product obtained by curing an epoxy resin composition containing an internal mold release agent, and a fiber-reinforced composite material comprising reinforcing fibers (A) The epoxy resin is an epoxy resin containing 60 to 100 parts by mass of a bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less in 100 parts by mass of the total epoxy resin, (d) A fiber-reinforced composite material, wherein the release agent is contained in an amount of 9 to 15 parts by mass with respect to 100 parts by mass of the total epoxy resin. The bifunctional epoxy resin having a viscosity at 25 ° C. of 3000 mPa · s or less is at least selected from the group consisting of bisphenol F type epoxy resin, diglycidyl aniline, diglycidyl o-toluidine, resorcinol type epoxy resin, and alicyclic epoxy resin. The fiber-reinforced composite material according to claim 1, comprising one type. (D) The fiber-reinforced composite material according to claim 1 or 2, wherein the internal release agent is a fatty acid ester release agent that is liquid at 25 ° C. The fiber-reinforced composite material according to any one of claims 1 to 3 , wherein the reinforcing fibers are carbon fibers.