JP4687167B2 - Epoxy resin composition, prepreg and fiber reinforced composite material - Google Patents

Description

  The present invention relates to an epoxy resin composition useful for fiber reinforced composite materials, semiconductor encapsulants, laminates, adhesives, paints, etc., a prepreg as an intermediate substrate for obtaining fiber reinforced composite materials, and sports applications, aircraft The present invention relates to a carbon fiber reinforced composite material suitable for space use and general industrial use, and particularly to a fiber reinforced composite material that can be suitably used for tubular body materials such as golf shafts, fishing rods, and automobile propeller shafts.

  A one-pack type epoxy resin composition consisting of an epoxy resin composed of a compound having an epoxy group in the molecule and its curing agent, has excellent mechanical strength, chemical resistance, heat resistance, metal members and reinforcing fibers. For example, it is used as a matrix resin for fiber-reinforced composite materials in combination with paints / paving materials, adhesives, or reinforcing fibers such as carbon fibers.

  Fiber reinforced composite material consisting of reinforced fiber and matrix resin is lightweight and has excellent strength characteristics, so it can be used for sports applications such as golf shafts, fishing rods, rackets such as tennis and badminton, sticks such as hockey, and aerospace applications. Although widely used in general industrial applications such as automobiles / ships, bathtubs, helmets, etc., in order to meet the demand for further weight reduction, there is a need for a technique for improving the strength characteristics of such materials.

  For example, a technique is known in which an epoxy resin composition having a specific range of average epoxy equivalent and controlled so that the cured resin has a specific range of glass transition temperature and rubber elastic modulus is used as a matrix resin ( For example, see Patent Document 1). However, in such a method, when the average epoxy equivalent is increased, the heat resistance tends to be insufficient, and this method alone cannot satisfy the demand for a higher performance fiber-reinforced composite material, and the strength characteristics are not improved. A technique for further improvement was required.

  In addition, a technique is known in which a cured resin has a specific range of compressive modulus of 2.4 to 3.5 GPa and an epoxy resin that is controlled to have a nominal strain at compression fracture of 50% or more as a matrix resin ( For example, see Patent Document 2). However, in such a method, when the compressive elastic modulus is increased, the compressive fracture nominal strain or the heat resistance tends to decrease, and there are cases where the compatibility between the heat resistance and the strength characteristics is still insufficient.

  Furthermore, a technique is known in which an epoxy resin controlled to have a compression yield stress of 110 to 140 MPa and a compression yield nominal strain of 6 to 10% of the cured resin is used as a matrix resin (see, for example, Patent Document 3).

  However, in the prior art, when attempting to increase the compressive fracture nominal strain or compressive elastic modulus of the resin, the heat resistance tends to decrease, and as a result, both heat resistance and strength characteristics are still insufficient.

As described above, the epoxy resin composition and the fiber reinforced composite material capable of exhibiting excellent heat resistance and mechanical strength have not yet been obtained, although certain effects can be obtained even with these known techniques.
JP 2002-327041 A JP 2003-128746 A JP 2003-277471 A

  An object of the present invention is to solve the above-mentioned problems, an epoxy resin composition having excellent heat resistance and strength characteristics, a prepreg excellent in handleability obtained by using the resin composition, and further lightweight. Another object of the present invention is to provide a fiber-reinforced composite material having excellent strength characteristics.

The present invention has the following configuration in order to achieve the above-described object. That is, an epoxy resin composition containing the following constituent elements [A], [B], and [C], wherein the constituent element [A] is selected from [A1] biphenyl, naphthalene, fluorene, dicyclopentadiene, and an oxazolidone ring. look containing one or more epoxy resins having at least one skeleton selected for component [C] is a component [a] 100 parts by weight, an epoxy resin composition that contains 3 to 35 parts by weight.
[A] Epoxy resin [B] Curing agent [C] p-tert-butylphenylglycidyl ether, hexahydrophthalic acid diglycidyl ester, diglycidylaniline, p-aminophenol type liquid epoxy compound, and aniline The prepreg composed of the epoxy resin composition and the reinforcing fiber, and further a fiber-reinforced composite material obtained by curing the prepreg.

  The epoxy resin composition of the present invention has good compression modulus, compression fracture nominal strain, compression yield stress, and heat resistance of the cured resin.

  Moreover, since the prepreg of the present invention has good handleability and excellent moldability, it can provide a fiber-reinforced composite material having excellent mechanical properties.

  Furthermore, the fiber reinforced composite material of the present invention is lightweight and has excellent mechanical properties such as, for example, the torsional strength of a cylindrical fiber reinforced composite material.

  As a result of intensive studies by the present inventors to solve the above-mentioned problems, a resin composition that exhibits a high level of compressive elastic modulus, compressive yield stress, and compressive fracture nominal strain is obtained for the cured resin for carbon fiber reinforced composite materials. The present inventors have found that the torsional strength of a tubular (cylindrical) fiber reinforced composite material can be remarkably improved, and have found a resin formulation capable of simultaneously satisfying the properties of the cured resin with heat resistance.

The epoxy resin composition of the present invention is an epoxy resin composition containing the following components [A], [B] and [C], wherein the component [A] is [A1] biphenyl, naphthalene, fluorene, di- cyclopentadiene, and looking containing one or more epoxy resins having at least one skeleton selected from oxazolidone ring, with respect to component [C] is a component [a] 100 parts by weight, include 3 to 35 parts by weight It is an epoxy resin composition.
[A] Epoxy resin [B] Curing agent [C] p-tert-butylphenylglycidyl ether, hexahydrophthalic acid diglycidyl ester, diglycidylaniline, p-aminophenol type liquid epoxy compound, and aniline At least one or more kinds of reactive compounds The epoxy resin as the constituent element [A] of the present invention is a compound having an average of more than one epoxy group in the molecule. Here, the epoxy resin may be one kind of epoxy resin or a mixture of plural kinds of epoxy resins. In addition, when the component [C] mentioned later corresponds to an epoxy resin, it shall not be included in the component [A]. In addition, when the constituent element [C] corresponds to the curing agent, it is not included in the constituent element [B].

In the present invention, it is necessary that the constituent element [A] contains at least one epoxy resin having at least one skeleton selected from [A1] biphenyl, naphthalene, fluorene, dicyclopentadiene, and an oxazolidone ring. By including at least one or more of such epoxy resins, it is possible to improve the compression elastic modulus, compression yield stress, compression fracture nominal strain, and heat resistance of the cured resin.

  Commercially available epoxy resins having a biphenyl skeleton may be used. For example, Epicoat (registered trademark) YX4000, Epicoat YX4000H, Epicoat YL6121 (above, manufactured by Japan Epoxy Resins Co., Ltd.), NC3000, NC3000H (above, Nippon Kayaku) For example).

  As epoxy resins having a naphthalene skeleton, Epicron (registered trademark) HP4032, Epicron HP4032D, Epicron H4032H, Epicron EXA4750, Epicron EXA4700, Epicron EXA4701 (above, Dainippon Ink Industries, Ltd.), NC7000L, NC7300L (above, Nippon Kayaku) Medicine).

  Examples of the epoxy resin having a fluorene skeleton include Ogsol (registered trademark) PG and Ogsol (registered trademark) EG (manufactured by Nagase ChemteX Corporation).

  As an epoxy resin having a dicyclopentadiene skeleton, Epicron (registered trademark) HP7200L (epoxy equivalent: 245 to 250, softening point: 54 to 58 ° C.), Epicron HP7200 (epoxy equivalent: 255 to 260, softening point: 59 to 63 ° C.), Epicron HP7200H (epoxy equivalent 275-280, softening point 80-85 ° C.), Epicron HP7200HH (epoxy equivalent 275-280, softening point 87-92 ° C.) (above, Dainippon Ink & Chemicals, Inc.), XD-1000- L (epoxy equivalent 240-255, softening point 60-70 ° C.), XD-1000-2L (epoxy equivalent 235-250, softening point 53-63 ° C.) (Nippon Kayaku Co., Ltd.), Tactix (registered) Trademark) 556 (epoxy equivalents 215 to 235, softening point 79 ° C.) (Huntsma It can be mentioned Inc Co., Ltd.) and the like.

  Examples of the epoxy resin having an oxazolidone ring skeleton include Araldite AER (registered trademark) 4152, XAC4151 (manufactured by Asahi Kasei Epoxy Co., Ltd.) and the like.

5% to 50% by weight of epoxy resin having at least one skeleton selected from [A1] biphenyl, naphthalene, fluorene, dicyclopentadiene, and oxazolidone ring is included in 100% by weight of the component [A] in the present invention. It is preferable. It is more preferably 7 to 45% by weight, and further preferably 10 to 40% by weight. If it is less than 5% by weight, the effect of improving the heat resistance, compressive fracture nominal strain, and compressive yield stress of the cured resin may be small. If it exceeds 50% by weight, the viscosity becomes too high, and the moldability in the case of a prepreg may deteriorate.

  Although an epoxy resin with a naphthalene skeleton or a fluorene skeleton has a slightly small effect of improving the compression fracture nominal strain, it is preferable in terms of a large effect of improving the heat resistance, and an epoxy resin having an oxazolidone ring skeleton has a small effect of improving the compression modulus. The effect of improving the compressive fracture nominal strain is preferable because of its large effect. An epoxy resin having a biphenyl skeleton is more preferable because it has an excellent effect of improving compressive fracture nominal strain and yield stress, and an epoxy resin having a dicyclopentadiene skeleton is excellent in heat resistance, compressive fracture nominal strain, and compressive yield stress. This is particularly preferable because of its excellent improvement effect.

The epoxy resin of the component [A] in the present invention further includes an epoxy resin ( [A2] ) having an average epoxy equivalent of preferably 1000 to 10,000, more preferably 1200 to 8000, and further preferably 1500 to 5000. It is good.

  By using such an epoxy resin, the crosslink density of the cured resin can be lowered and the plastic deformation ability can be improved. Conventionally, when an epoxy resin having an average epoxy equivalent as high as 1000 to 10000 was used, the viscosity of the epoxy resin composition was too high to be suitable for prepreg production, but the epoxy resin composition was combined with the component [C]. It is possible to increase the plastic deformation ability without increasing the viscosity of the resin. As a result, it is particularly preferable because it is possible to achieve both the handleability of the prepreg and the mechanical properties of the obtained fiber-reinforced composite material. That is, by using an epoxy resin having an average epoxy equivalent of 1000 or more, the compressive fracture nominal strain can be greatly improved while maintaining heat resistance and compressive yield stress. Furthermore, surprisingly, when an epoxy resin having an average epoxy equivalent of 1000 or more is blended, a prepreg excellent in handleability can be obtained even after leaving for a day when the prepreg release film is peeled off.

  When an epoxy resin having an average epoxy equivalent of more than 10,000 is used, the impregnation of the resin becomes insufficient in the prepreg manufacturing process due to high viscosity, or the shapeability of the resulting prepreg decreases, The physical properties of the fiber reinforced composite material may be deteriorated.

[A2] The blending amount of the epoxy resin having an average epoxy equivalent of 1000 to 10000 is preferably 3 to 60% by weight in 100% by weight of the component [A]. 5 to 55% by weight is more preferable, and 10 to 50% by weight is more preferable. If it is less than 3% by weight, the effect of improving the compressive fracture nominal strain may be small. If it exceeds 60% by weight, the impregnation of the resin may be insufficient in the prepreg manufacturing process, or the shapeability of the resulting prepreg may be reduced. However, the physical properties of the fiber reinforced composite material may be deteriorated.

  As an epoxy resin commercial product with an average epoxy equivalent of 1000 or more, Epicoat (registered trademark) 1005F (manufactured by Japan Epoxy Resin Co., Ltd., average epoxy equivalent 1000), ST-5100 (manufactured by Toto Kasei Co., Ltd., average epoxy) Equivalent 1000), ST-4100D (manufactured by Toto Kasei Co., Ltd., epoxy equivalent 1000), Epicoat 1005H (manufactured by Japan Epoxy Resin Co., Ltd., average epoxy equivalent 1290), Epicote 5354 (manufactured by Japan Epoxy Resins Co., Ltd., average epoxy) Equivalent 1650), DER-667 (Dow Chemical Japan Co., Ltd., average epoxy equivalent 1775), EP-5700 (Asahi Denka Kogyo Co., Ltd., average epoxy equivalent 1925), Epc 7050 (Dainippon Ink Co., Ltd.) Average epoxy equivalent 1925), YD-017 (Tohto Kasei) Co., Ltd., average epoxy equivalent 1925), Epicoat 1007 (Japan Epoxy Resin Co., Ltd., average epoxy equivalent 1950), Epicoat 5057 (Japan Epoxy Resin Co., Ltd., average epoxy equivalent 2250), Epicoat 4007P (Japan Epoxy Resin) Manufactured by Co., Ltd., average epoxy equivalent 2270), DER-668 (manufactured by Dow Chemical Japan Co., Ltd., average epoxy equivalent 2750), YD-019 (manufactured by Toto Kasei Co., Ltd., average epoxy equivalent 2850), EP-5900 ( Asahi Denka Kogyo Co., Ltd., average epoxy equivalent 2850), Epicoat 1009 (Japan Epoxy Resin Co., Ltd., average epoxy equivalent 3300), Epicoat 4110P (Japan Epoxy Resin Co., Ltd., average epoxy equivalent 3800), YD- 020N (Toto Kasei Co., Ltd.) , Average epoxy equivalent 3900), Epicoat 1010 (Japan epoxy resin, average epoxy equivalent 4000), Epicoat 4010P (Japan Epoxy Resin Co., Ltd., average epoxy equivalent 4400), DER-669 (Dow Chemical Japan Co., Ltd., average) Epoxy equivalent 4500), YD-020H (Toto Kasei Co., Ltd., average epoxy equivalent 5250), Epikote 1256 (manufactured by Japan Epoxy Resin Co., Ltd., average epoxy equivalent 7700), Epicote 4250 (manufactured by Japan Epoxy Resin Co., Ltd., average) Epoxy equivalent 8500), Epicoat 4275 (manufactured by Japan Epoxy Resin Co., Ltd., average epoxy equivalent 8500), Epicoat 5203 (manufactured by Japan Epoxy Resin Co., Ltd., average epoxy equivalent 9000), Epicorte 4210 (Japan Epoch) And an average epoxy equivalent of 10,000) manufactured by Xyresin Corporation. Among these, a resin having a bisphenol A-type skeleton is particularly preferable from the viewpoint of both plastic deformation ability and heat resistance.

  The constituent element [A] of the present invention may contain an epoxy resin other than the epoxy resin, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, bisphenol S type epoxy. Resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidyl ether type epoxy resin such as aliphatic epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, rubber modified epoxy resin, etc. may be blended .

  Here, it is preferable to include a polyfunctional epoxy resin such as a glycidylamine type in the component [A] from the viewpoints of improving the elastic modulus and heat resistance. From the viewpoint of heat resistance, the content is preferably 20 to 90% by weight, more preferably 30 to 80% by weight, and still more preferably 40 to 70% by weight. On the other hand, the polyfunctional epoxy resin tends to decrease the compressive fracture nominal strain of the cured resin as the blending amount increases. Therefore, considering only the case where it is desired to particularly improve the compressive fracture nominal strain, the component [A] 100 In the wt%, the polyfunctional compounding amount is preferably less than 60 wt%, more preferably less than 30 wt%, still more preferably less than 20 wt%, and particularly preferably not contained.

  Further, from the viewpoint of further improving the resin compressive fracture nominal strain, it is preferable to include a bifunctional epoxy resin, preferably 40% by weight or more, more preferably 50% by weight or more, in 100% by weight of the component [A]. 60% by weight or more is more preferable.

  In the present invention, a curing agent for component [B] is required. The component [B] is not particularly limited as long as it is a curing agent. For example, an amine curing agent, an acid and acid anhydride curing agent, a phenol curing agent, a polyaminoamide curing agent, a Lewis acid, and a Bronsted acid. Polymercaptan-based curing agents, isocyanates, blocked isocyanate compounds, and the like can be used.

In the present invention, the viscosity at 25 ° C. of the components [C] becomes 0.001~1Pa · s. Such viscosity can be measured with an E-type viscometer according to JIS Z8803 (1991).

  By blending a compound such as component [C], the free volume of the cured resin can be filled and the elastic modulus can be improved without lowering the compression fracture nominal strain. Yield stress is improved. By combining the constituent elements [A] and [C], it becomes possible to give a resin composition excellent in both heat resistance and compressive elastic modulus, compressive fracture nominal strain, and compressive yield stress, and the epoxy resin composition The fiber reinforced composite material using as a matrix resin can achieve both heat resistance and excellent mechanical strength, specifically cylindrical torsional strength.

Examples of commercially available components [C] include aniline (viscosity 0.004 Pa · s, manufactured by Wako Pure Chemical Industries, Ltd.) , Denacol EX-146 (viscosity 0.02 Pa · s, Nagase ChemteX Corporation). )), GAN (viscosity 0.16 Pa · s, manufactured by Nippon Kayaku Co., Ltd.) , AK601 (viscosity 0.35 Pa · s, Nippon Kayaku Co., Ltd.), Ep190P (viscosity 0.85 Pa · s, Japan Epoxy) Resin Co., Ltd.), Ep191P (viscosity 0.85 Pa · s, manufactured by Japan Epoxy Resin Co., Ltd.) , Ep630 (viscosity 1.0 Pa · s, manufactured by Japan Epoxy Resin Co., Ltd.), and the like.

The component [C] in the present invention is contained in an amount of 3 to 35 parts by weight with respect to 100 parts by weight of the component [A] . 5-30 weight part is preferable and it is more preferable that 10-25 weight part is contained. If it is less than 3 parts by weight, the effect of improving the compressive modulus and compressive yield stress may not be sufficient. Moreover, when it exceeds 35 weight part, it exists in the tendency for heat resistance to fall.

  The constituent element [C] in the present invention preferably has two portions that form a chemical bond with at least one of the constituent element [A] and the constituent element [B]. The effect of maintaining the heat resistance is small at one place where a chemical bond is formed, and if there are three or more places, the elongation of the cured resin tends to decrease.

The component [C] in the present invention preferably has an aromatic ring. By having an aromatic ring, a decrease in heat resistance can be minimized .

  It is preferable that the average epoxy equivalent of all the epoxy resins in this invention is 230-400. Here, the total epoxy resin literally means all epoxy resins contained in the epoxy resin composition, and when [C] is an epoxy resin, the average epoxy equivalent determined by including not only [A] but also [C] Means.

  By mix | blending raw material resin so that it may become this epoxy equivalent, the crosslinking density of the resin cured material of the resin composition obtained can be made into a preferable range. That is, the larger the epoxy equivalent, the lower the density of the epoxy group that becomes a cross-linking point, and the low cross-linking density of the cured product can increase the plastic deformation ability. When the average epoxy equivalent is less than 230, the plastic deformation ability of the resin cured product tends to decrease, and the torsional strength in the case of a cylindrical fiber reinforced composite material does not increase so much. On the other hand, when it exceeds 400, the elastic modulus and heat resistance of the resin cured product may be lowered, or the viscosity of the resin composition may be too high. More preferably, it is 240-370, More preferably, it is 250-350.

  Here, the epoxy equivalent is a value obtained by dividing the mass (g) of the epoxy resin by the number of moles of all epoxy groups contained in the resin. The epoxy equivalent of a mixture of resins can be quantified by direct titration of the mixture, but can also be determined by calculation from the individual average epoxy equivalents and loadings.

  As the curing agent for the component [B] in the present invention, a solid curing agent having a melting point or a softening point of 50 ° C. or higher is preferably used. Specifically, 4,4′-diaminodiphenylsulfone (melting point 176 ° C.), 3,3′-diaminodiphenylsulfone (melting point 170 ° C.), 4,4′-diaminodiphenylmethane (melting point 92 ° C.), 4,4′- Aromatic amines such as methylenebis- (2,6-diethyl) aniline (melting point 88 ° C.), guanidine compounds such as dicyandiamide (melting point 209 ° C.), adipic acid dihydrazide (melting point 179 ° C.), Amicure VDH (manufactured by Ajinomoto Co., Inc.) Melting point 120 ° C.), Amicure LDH (Ajinomoto Co., Ltd., melting point 180 ° C.), Amicure UDH (Ajinomoto Co., Ltd., melting point 160 ° C.) and other organic hydrazide compounds, Amicure PN23 (Ajinomoto Co., Ltd., melting point 100 ° C.) ), Amine adducts such as Amicure MY24 (Ajinomoto Co., Inc., melting point 120 ° C.) and the like. But the present invention is not limited to this. Among these, dicyandiamide is preferable from the viewpoint of thermal stability and curability.

  Moreover, when producing a prepreg, it is preferable from a heat-stable point to mix a hardening | curing agent with an epoxy resin at the temperature below melting | fusing point of a hardening | curing agent. Even when the particles having a large particle size are impregnated under pressure, they do not enter the reinforcing fiber bundle. For this reason, when the average particle diameter of dicyandiamide is increased, the amount of the curing agent in the reinforcing fiber bundle is decreased, and the curing reaction is partially incomplete, which may cause deterioration of the mechanical properties of the composite material. For these reasons, the average particle diameter of dicyandiamide is preferably 10 μm or less, and more preferably 5 μm or less. Here, the average particle diameter means volume average.

  It is preferable to use 2 to 10 parts by weight of dicyandiamide with respect to 100 parts by weight of the total epoxy resin. If it is less than 2 parts by weight, the curing reaction may be incomplete, and if it exceeds 10 parts by weight, it may cause a decrease in physical properties.

  When dicyandiamide is used alone as a curing agent, heating at 180 ° C. for about 2 hours is necessary to obtain a sufficient curing reaction rate. Therefore, in addition to dicyandiamide, a curing agent such as aromatic amine and aliphatic amine, and a curing accelerator can be used in combination.

  Although it does not specifically limit as a hardening accelerator, An imidazole compound, a urea compound, tertiary amine, etc. can be mentioned. In order to increase the storage stability of the resin composition, a microcapsule type curing accelerator whose surface is coated with a resin may be used. Among these, inclusion of a urea compound as a curing accelerator is particularly preferably used because a sufficient accelerating effect can be obtained without substantially impairing the storage stability of the resin composition. Specific examples of urea compounds include 3- (3,4-dichlorophenyl) -1,1-dimethylurea, trade name “DCMU99” manufactured by Hodogaya Chemical Co., Ltd., 3-phenyl-1,1-dimethylurea, trade name “Omicure” 94 "RTI Japan, Toluene bis (dimethylurea), trade name" Omicure 24 "made by PTI Japan, 4,4'-methylenebis (phenyldimethylurea), trade name" Omicure 52 "made by RTI Japan. It is not limited to.

  It is preferable to use 1 to 10 parts by weight of the urea compound with respect to 100 parts by weight of the total epoxy resin. If the amount is less than 1 part by weight, the accelerating effect is weakened. Therefore, the resin composition may not be sufficiently cured by heating at 135 ° C. for about 2 hours. Conversely, if the amount exceeds 10 parts by weight, the accelerating effect is too strong. The storage stability of the resin composition at high temperatures may be insufficient.

  A thermoplastic resin, a thermoplastic elastomer, an elastomer, inorganic particles, etc. can be added to the epoxy resin composition in the present invention as necessary.

  As a thermoplastic resin, what is soluble in an epoxy resin is preferable. Moreover, even if it is insoluble in the epoxy resin, it is preferably pulverized and finely divided, and can be blended.

  Specifically, polyamide, polyamideimide, polyaramide, polyarylene oxide, polyarylate, polyimide, polyethylene terephthalate, polyetherimide, polyether terephthalate, polyetherimide, polyetheretherketone, polyethersulfone, polycarbonate, polycarbonate, polyacetic acid Vinyl, polystyrene, polysulfone, polyvinyl acetal resin, polyphenylene oxide, polyphenylene sulfide, polypropylene, polybenzimidazole, polymethyl methacrylate and the like are used.

  Of these, polyamide is particularly effective in improving toughness and impact resistance without substantially impairing the elastic modulus of the cured product.

  In particular, polyterimide and polyethersulfone are effective in improving the adhesion to carbon fiber without impairing the heat resistance of the cured product.

  In addition, polyvinyl acetal resin and polymethyl methacrylate are easily soluble with epoxy resin by heating, improving adhesion to carbon fibers and maintaining the viscosity without compromising the heat resistance of the cured product. Therefore, it is particularly preferable as the thermoplastic resin in the present invention.

  Specific examples of the polyvinyl acetal resin include polyvinyl formals such as “Vinylec” K, L, H, E (manufactured by Chisso Corporation), polyvinyl acetals such as “ESREC” K (manufactured by Sekisui Chemical Co., Ltd.), “Sleck” B (manufactured by Sekisui Chemical Co., Ltd.) and “Denka Butyral” (manufactured by Denki Kagaku Kogyo Co., Ltd.) are listed as polymethyl methacrylates. BR-88, BR-108 (Mitsubishi Rayon Co., Ltd.), “Matsumoto Microsphere” M, M100, M500 (Made Matsumoto Yushi Seiyaku Co., Ltd.), etc. is not.

  The thermoplastic resin is preferably contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the component [A]. The amount is more preferably 0.1 to 7 parts by weight, and further preferably 0.1 to 5 parts by weight. If it exceeds 10 parts by weight, the impregnation property of the resin may be insufficient in the prepreg production process, or the shapeability of the resulting prepreg may be deteriorated, resulting in a decrease in the physical properties of the fiber-reinforced composite material. If it is less than 0.1, the effect of improving the adhesion between the matrix resin and the reinforcing fibers when the fiber-reinforced composite material is obtained may not be sufficient.

  The glass transition temperature of the epoxy resin composition of the present invention is preferably 100 to 140 ° C. 110-140 ° C is more preferable, and 115-140 ° C is more preferable. If it is less than 100, the heat resistance is insufficient in sports applications. When the temperature exceeds 140 ° C., the residual thermal stress is large, and the mechanical properties may be lowered when a fiber-reinforced composite material after heat curing is obtained.

  The prepreg of the present invention is obtained by impregnating a reinforcing fiber with the epoxy resin composition of the present invention.

  The reinforcing fiber used in the prepreg of the present invention is not particularly limited, and carbon fiber, glass fiber, aramid fiber, boron fiber, alumina fiber, silicon carbide fiber, vapor grown carbon fiber, carbon nanotube, and the like can be used. Two or more kinds of these fibers can be mixed. Among them, it is preferable to use mainly carbon fibers having a tensile modulus of 200 to 500 GPa in order to obtain a material excellent in lightweight performance and mechanical properties.

  As the form and arrangement of the reinforcing fibers contained in the prepreg of the present invention, for example, those aligned in one direction, woven fabric (cross), tow, mat, knit and the like are used. Among them, it is preferable to adopt one that is aligned in one direction because the strength characteristics can be easily designed by the laminated structure.

  The reinforced fiber weight content of the prepreg of the present invention and the fiber-reinforced composite material is 60 to 90% by weight, more preferably 70 to 85% by weight. When the epoxy resin composition of the present invention is used, the effect of improving the moldability of the prepreg, in particular, the moldability when molding a tubular body (cylindrical fiber reinforced composite material) is further enhanced in such a high fiber content region. It becomes clear and excellent. Further, by using the particularly preferable resin composition, it is possible to control the change with time of the handling property in the prepreg. Furthermore, the quality and performance of the fiber-reinforced composite material obtained can be made excellent.

Preferably the fiber weight per unit area of the prepreg of the present invention is 40~250g / ^{m 2,} preferably further is 50 to 200 g / ^{m 2.} When the fiber weight per unit area is less than 40 g / m ² , the shape retention of the prepreg is lowered and the handling becomes somewhat difficult. Moreover, when the fiber weight per unit area exceeds 250 g / m < ² >, the fiber alignment inside a prepreg tends to be disturbed, and it becomes difficult to become a high-performance fiber-reinforced composite material.

  Thus, even with a prepreg having a small fiber weight per unit weight, it is possible to obtain excellent characteristics in the formability of a cylinder (tubular body) and the quality and performance after curing.

  The fiber weight per unit area and the fiber content mentioned here can be determined by eluting the resin from the prepreg with an organic solvent and measuring the fiber weight.

  For example, the fiber-reinforced composite material of the present invention is molded in the following manner. After laminating the pattern obtained by cutting the prepreg, the fiber reinforced composite material is obtained by heat curing the resin while applying pressure to the laminate. Methods for applying heat and pressure include a press molding method, an autoclave molding method, a vacuum pressure molding method, a sheet winding method, and an internal pressure molding method. Especially for sports equipment, the sheet winding method or the internal pressure molding method is preferable. Adopted.

  The sheet winding method is a method of forming a cylindrical object by winding a prepreg around a mandrel, and is suitable for producing a rod-shaped body such as a golf shaft or a fishing rod. Specifically, a prepreg is wound around a mandrel and fixed so that the prepreg does not peel off from the mandrel, or a tape-like thermoplastic resin film (wrapping tape) is provided on the outside of the prepreg in order to make the molding pressure insoluble. Is wound and the resin is heated and cured in an oven, and then the core metal is removed to obtain a cylindrical molded product.

  In the internal pressure molding method, a preform in which a prepreg is wound around an internal pressure applying body made of a thermoplastic resin is set in a mold, high pressure air is introduced into the internal pressure applying body, and the mold is heated at the same time. This is a method for forming a fiber-reinforced composite material. This internal pressure molding method is suitably used when molding a complicated shape such as a specially shaped golf shaft or bat, particularly a racket such as tennis or badminton.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, the evaluation method in an Example is as showing below. Table 1, Table 2, Table 3, Table 4, Table 5, and Table 6 collectively show the resin composition, resin composition characteristics, prepreg characteristics, and fiber reinforced composite material characteristics of each example.

A. Compression test of cured resin The epoxy resin composition was heated to 80 ° C., defoamed with a vacuum pump, poured into a mold, and heat-treated at 130 ° C. for 90 minutes to obtain a thickness of 6 ± 0.2 mm. A cured resin plate was prepared. Next, a cube-pair test piece having a side length of 6 ± 0.2 mm was cut out from the cured resin plate, the test speed was 1 ± 0.2 mm / min, and the other conditions were compression elastic according to the conditions according to JISK7181. Rate, compressive yield stress, and nominal strain at compressive failure were measured. The number of tests was n = 6, and the average values were compression elastic modulus, compression yield stress, and nominal strain at the time of compression fracture, respectively.

B. Glass transition temperature (Tg)
A. The glass transition temperature was measured with a differential scanning calorimeter (DSC) in accordance with JIS K7121 using the cured resin produced in 1. A sealed sample container having a capacity of 50 μl was packed with 5 to 20 mg of sample, heated to 30 to 200 ° C. at a heating rate of 40 ° C./min, and measured. In this case, Pyris1DSC manufactured by PerkinElmer was used as a measuring device.

  Specifically, in the portion showing the step change of the obtained DSC curve, the straight line equidistant from the extended straight line of each baseline in the vertical axis direction and the curve of the step change portion of the glass transition intersect. The temperature at the point was taken as the glass transition temperature.

C. Preparation of prepreg a. Production of Bias Material The epoxy resin composition was applied to a release paper using a reverse roll coater to produce a resin film. Next, resin films are stacked on both sides of carbon fiber “Treca (registered trademark) M40SC-12K (manufactured by Toray Industries, Inc.)” having a tensile elastic modulus of 392 GPa arranged in one direction, and heated and pressurized (130 ° C., 0 4 MPa), the resin was impregnated to produce a unidirectional prepreg a having a fiber weight per unit area of 100 g / m ² and a fiber weight content of 76%.
b. Production of Straight Material An epoxy resin composition was applied to a release paper using a reverse roll coater to produce a resin film. Next, a resin film is laminated on both sides of a carbon fiber trading card (registered trademark) T800H-12K (manufactured by Toray Industries, Inc.) having a tensile elastic modulus of 294 GPa arranged in one direction, and heated and pressurized (130 ° C., 0. 4 MPa), the resin was impregnated to prepare a unidirectional prepreg b having a basis weight of 116 g / m ² and a fiber weight content of 76%.

D. Impregnation property The impregnation property of the finished prepreg was evaluated on a four-point scale by visual and tactile sensation. In the table, “Excellent” is indicated by “Good”, “Good” is indicated by “Good”, “Slightly unimpregnated part” is indicated by “△”, and Impregnation failure is indicated by “X”.

E. Production of Cylindrical Fiber Reinforced Composite Material A cylindrical fiber reinforced composite having a laminated configuration of [0 ₃ / ± 45 ₃ ] in the cylindrical axis direction and an inner diameter of 10 mm by the following operations (a) to (e). The material was made. A stainless steel round bar having a diameter of 10 mm (both 1000 mm in length) was used for the mandrel.
(A) Two unidirectional prepregs a were cut into a rectangle of 800 mm in length and 103 mm in width so that the fiber direction was 45 degrees with respect to the axial direction of the mandrel. Immediately after the two release films were peeled, they were bonded so that the fiber directions intersected each other and shifted by 16 mm in the lateral direction (corresponding to the half circumference of the mandrel).
(B) The release paper of the bonded prepreg (bias material) was peeled off and wound around the release mandrel so that the longitudinal direction of the prepreg and the axial direction of the mandrel coincided.
(C) On top of that, a prepreg b (straight material) cut into a rectangle of length 800 mm × width 112 mm so that the fiber direction is in the vertical direction so that the vertical direction of the prepreg and the axial direction of the mandrel coincide. Wound around.
(D) Wrapping tape (heat-resistant film tape) was wound, and heat-molded in a curing furnace at 130 ° C. for 2 hours.
(E) After molding, the mandrel was extracted and the wrapping tape was removed to obtain a cylindrical fiber reinforced composite material.

F. Evaluation of cylindrical formability E. The release paper of the prepreg (bias material) that was bonded together was peeled off, and the three-stage evaluation was made based on the tactile sensation when the longitudinal direction of the prepreg and the axial direction of the mandrel were wound around the release mandrel. Extremely good is indicated by ◯, good is indicated by 、, slightly wound, and difficult to wind by △.

  This was performed for the case where the prepreg was pasted immediately after the release film was peeled off from the surface of the prepreg, and the case where the prepreg which was left for 1 day in an atmosphere of 23 ° C. and 50% humidity after the film was pasted.

G. Measurement of Torsional Strength of Cylindrical Fiber Reinforced Composite Material A 400 mm long test piece was cut out from a cylindrical fiber reinforced composite material with an inner diameter of 10 mm, “Golf Club Shaft Certification Criteria and Standard Confirmation Method” (Product Safety Association, Trade) The torsion test was conducted according to the method described in the Minister of Industry 5th No. 2087 (1993). The test piece gauge length was 300 mm, and 50 mm at both ends of the test piece was held with a fixing jig. The torsional strength was obtained by the following formula.

Torsional strength (N · m · deg) = Breaking torque (N · m) × Torsion angle at break (deg)
Example 1
Each raw material was mixed by the compounding ratio shown in Table 1, and the epoxy resin composition was produced. The resulting resin composition had an excellent resin composition with a compression modulus of 2.73 GPa, a compressive yield stress of 130.3 MPa, a compressive fracture nominal strain of 60.0%, and a heat resistance of 114 ° C. Using such an epoxy resin composition, a prepreg and a cylindrical fiber reinforced composite material were produced by the above-described method. As shown in Table 1, the obtained prepreg was excellent in impregnation property and cylindrical formability. In addition, the torsional strength of the cylindrical fiber reinforced composite material was as high as 2570 N · m · deg.

(Examples 2 to 5)
As shown in Table 1, an epoxy resin composition, a prepreg, and a cylindrical fiber reinforced composite material were produced in the same manner as in Example 1 except that the amount of component [C] was changed. The resulting epoxy resin composition had excellent compressive modulus, compressive yield stress, compressive fracture nominal strain, prepreg impregnation property, cylindrical moldability, and torsional strength of the cylindrical fiber reinforced composite material. On the other hand, when the constituent element [C] is large, the heat resistance tends to be slightly lowered.

(Comparative Example 1)
As shown in Table 1, an epoxy resin composition, a prepreg, and a cylindrical fiber reinforced composite material were produced in the same manner as in Example 1 except that the component [C] was not blended. The resulting epoxy resin composition had a low resin compression modulus of 2.58 MPa and a compression yield stress of 127.4 MPa. Moreover, the impregnation property of the prepreg was slightly unimpregnated, and the torsional strength of the cylindrical reinforcing fiber composite material was 2450 N · m · deg, which was lower than in the examples.

(Example 6)
As shown in Table 2, the constituent element [C] was changed from GAN to Denacol Ex146, except that the part that reacts with the curing agent or the epoxy resin was changed to a reactive compound having one aromatic ring. An epoxy resin composition, a prepreg, and a cylindrical fiber reinforced composite material were produced by the method. The heat resistance of the obtained epoxy resin composition was 105 ° C., which was slightly inferior to that of Example 3, but the resin compressive modulus, compressive yield stress, and compressive fracture nominal strain were excellent. The impregnation property of the prepreg, the cylindrical formability, and the torsional strength of the cylindrical fiber reinforced composite material were also excellent.

(Example 7)
As shown in Table 2, the epoxy resin composition, prepreg, and cylindrical shape were produced in the same manner as in Example 3 except that the constituent element [C] was changed from GAN to AK601 and a reactive compound having no aromatic ring. A fiber reinforced composite material was prepared. The obtained epoxy resin composition had a heat resistance of 109 ° C., which was slightly inferior to that of Example 3. However, the resin compressive modulus, compressive yield stress, and compressive fracture nominal strain were excellent. The impregnation property of the prepreg, the cylindrical formability, and the torsional strength of the cylindrical fiber reinforced composite material were also excellent.

(Example 8)
As shown in Table 2, an epoxy resin composition, a prepreg, and a cylindrical fiber reinforced composite material were produced in the same manner as in Example 3 except that the component [C] was blended from GAN into aniline as a curing agent. . The obtained epoxy resin composition was excellent in heat resistance, resin compressive elastic modulus, compressive yield stress, and compressive fracture nominal strain. The impregnation property of the prepreg, the cylindrical formability, and the torsional strength of the cylindrical fiber reinforced composite material were also excellent.

Example 9
As shown in Table 2, the constituent element [C] was changed from GAN to Epicoat 630, except that the part that reacts with the curing agent or epoxy resin was changed to a reactive compound having three aromatic rings. An epoxy resin composition, a prepreg, and a cylindrical fiber reinforced composite material were prepared by the above method. The resulting epoxy resin composition had a compression fracture strain of 59.2%, which was slightly inferior to that of Example 3, but was excellent in heat resistance, resin compression modulus, and compression yield stress. The impregnation property of the prepreg, the cylindrical formability, and the torsional strength of the cylindrical fiber reinforced composite material were also excellent, although somewhat inferior to those of Example 3.

(Comparative Example 2)
As shown in Table 2, the epoxy resin composition, the prepreg, and the cylinder were formed in the same manner as in Example 3 except that the constituent element [C] was changed from GAN to DMAA to a reactive compound having no cyclic skeleton. A fiber reinforced composite material was prepared. The resulting epoxy resin composition had a heat resistance as low as 99 ° C.

(Comparative Example 3)
As shown in Table 2, the epoxy resin composition, prepreg, and cylindrical fiber reinforcement were prepared in the same manner as in Example 3 except that the component [C] was changed from GAN to Denacol Ex711 to a solid reactive compound. A composite material was prepared. The obtained prepreg was poorly impregnated and had a low torsional strength of 2480 N · m · deg.

(Examples 10 to 14)
As shown in Table 3, an epoxy resin composition, a prepreg, and a cylindrical fiber reinforced composite material were produced in the same manner as in Example 3 except that the blending amount of Epicron HP7200L included in the component [A] was changed. As the compounding amount increases, the heat resistance, compressive yield stress, and compressive fracture nominal strain improve, and the resulting epoxy resin composition has heat resistance, compression modulus, compressive yield stress, compressive fracture nominal strain, prepreg impregnation, Both the cylindrical formability and the torsional strength of the cylindrical fiber-reinforced composite material were excellent. When the blending ratio of HP7200L included in the component [A] is large, the formability of the cylinder tends to be slightly lowered.

(Comparative Example 4)
As shown in Table 3, the epoxy resin composition, the prepreg, and the cylindrical fiber reinforced were the same as in Example 3 except that the epiclone HP7200L contained in the component [A] was all changed to the bisphenol A type liquid epoxy resin epicoat 828. A composite material was prepared. The heat resistance, compressive yield stress, and compressive fracture nominal strain were reduced, and the torsional strength of the cylindrical fiber reinforced composite material was low.

(Example 15)
As shown in Table 4, the epoxy resin composition, the prepreg, and the epoxy resin composition were prepared in the same manner as in Example 12 except that the epiclone HP7200L having a dicyclopentadiene skeleton contained in the component [A] was changed to NC3000 having a biphenyl skeleton. A cylindrical fiber reinforced composite material was prepared. The obtained epoxy resin composition had a heat resistance of 114 ° C., which was slightly inferior to that of Example 12, but was excellent in all of the resin compression modulus, compression yield stress, and compression fracture nominal strain. The impregnation property of the prepreg, the cylindrical formability, and the torsional strength of the cylindrical fiber reinforced composite material were also excellent.

(Example 16)
As shown in Table 4, the epoxy resin composition and the prepreg were prepared in the same manner as in Example 12, except that the epiclone HP7200L having a dicyclopentadiene skeleton contained in the component [A] was changed to epiclone EXA4700 having a naphthalene skeleton. A cylindrical fiber reinforced composite material was prepared. The obtained epoxy resin composition had a compressive fracture strain of 58.7%, which is slightly inferior to that of Example 12, but was excellent in heat resistance, resin compression modulus, and compression yield stress. The impregnation property of the prepreg, the cylindrical moldability, and the torsional strength of the cylindrical fiber reinforced composite material were slightly inferior to those of Example 12, but sufficient.

(Example 17)
As shown in Table 4, the epoxy resin composition and the prepreg were prepared in the same manner as in Example 12 except that epiclone HP7200L having a dicyclopentadiene skeleton contained in the component [A] was changed to ogsol PG having a fluorene skeleton. A cylindrical fiber reinforced composite material was prepared. The obtained epoxy resin composition had a compressive fracture strain of 58.4%, which is slightly inferior to that of Example 12, but was excellent in heat resistance, resin compression modulus, and compression yield stress. The impregnation property of the prepreg, the cylindrical moldability, and the torsional strength of the cylindrical fiber reinforced composite material were slightly inferior to those of Example 12, but sufficient.

(Example 18)
As shown in Table 4, the epoxy resin composition was prepared in the same manner as in Example 12, except that epiclone HP7200L having a dicyclopentadiene skeleton contained in the component [A] was changed to araldite AER4152 having an oxazolidone ring skeleton. A prepreg and a cylindrical fiber reinforced composite material were prepared. The obtained epoxy resin composition had a compression modulus of 2.98 MPa, which was slightly inferior to that of Example 12, but was excellent in heat resistance, compression yield stress, and compression fracture nominal strain. The impregnation property of the prepreg, the cylindrical moldability, and the torsional strength of the cylindrical fiber reinforced composite material were slightly inferior to those of Example 12, but sufficient.

(Example 19)
As shown in Table 5, among the epoxy resins of the component [A], in the same manner as in Example 12, except that 5 parts of Epicoat 1004 having an average epoxy equivalent of 925 was replaced with Epicoat 1007 having an average epoxy equivalent of 1950, An epoxy resin composition, a prepreg, and a cylindrical fiber reinforced composite material were produced. The resulting epoxy resin composition was more excellent at a resin compression fracture nominal strain of 64.1%. The impregnation property of the prepreg was also excellent, and the cylindrical moldability after standing for 1 day was more excellent for the cylindrical molding. The torsional strength of the cylindrical fiber reinforced composite material after standing for 1 day was 2870 N · m · deg, which was more excellent.
(Examples 20 to 24)
As shown in Table 5, the epoxy resin composition, the prepreg, and the cylinder were the same as in Example 12 except that the blending ratio of Ep1007 having an average epoxy equivalent of 1950 was changed among the epoxy resins of the component [A]. A fiber reinforced composite material was prepared. The resulting epoxy resin composition had a resin compressive fracture nominal strain of 65.0 to 66.8%, which was more excellent. The impregnation property and cylindrical formability of the prepreg were excellent, and the torsional strength of the cylindrical fiber-reinforced composite material was 2910 to 3020 N · m · deg, which was more excellent. On the other hand, when the compounding ratio is increased, the impregnation property and the cylindrical molding tend to be slightly inferior.

(Example 25)
As shown in Table 6, among the epoxy resins of the component [A], except that Epicoat 1007 was changed to an Epicoat 1005H epoxy resin having an epoxy equivalent of 1290, an epoxy resin composition, A prepreg and a cylindrical fiber reinforced composite material were prepared. The resulting epoxy resin composition had a compressive fracture nominal strain of 64.7, which was slightly inferior, but was excellent in heat resistance, compression modulus, and compression yield stress. Moreover, the impregnation property and cylindrical moldability of the prepreg were also excellent. The torsional strength of the cylindrical fiber reinforced composite material was excellent, although it was slightly inferior to 2860 N · m · deg.

(Examples 26 to 28)
As shown in Table 6, the epoxy resin composition, the prepreg, and the cylinder were the same as in Example 21 except that Epicoat 1007 was changed to an epoxy resin having a higher epoxy equivalent among the epoxy resins of the component [A]. A fiber reinforced composite material was prepared. The compressive fracture nominal strain of the obtained epoxy resin composition was 66.7 to 67.7%, which was more excellent. Further, the impregnation property and cylindrical formability of the prepreg were excellent, and the torsional strength of the cylindrical fiber reinforced composite material was excellent at 3060-3080 N · m · deg. On the other hand, when the average epoxy equivalent was increased, the prepreg impregnation property and the cylindrical moldability tended to be slightly inferior.

(Example 29)
As shown in Table 6, among the epoxy resins of the component [A], the epoxy resin 100 was replaced with the bisphenol F epoxy resin Epicoat 1004P by the same method as in Example 21 except that the epoxy coating 1004P was changed to the epoxy resin. A resin composition, a prepreg, and a cylindrical fiber reinforced composite material were produced. The resulting epoxy resin composition had an excellent compressive fracture nominal strain of 61.2%. The impregnation property and cylindrical formability of the prepreg were also excellent, and the torsional strength of the cylindrical fiber-reinforced composite material was excellent at 2850 N · m · deg. However, the Tg decreased due to the use of the bisphenol F type epoxy resin, and the heat resistance tended to be slightly inferior.

(Examples 30 to 31)
As shown in Table 6, the epoxy resin composition was prepared in the same manner as in Example 21 except that the thermoplastic resin to be blended was changed from Vinylec K to the combined use of Vinylec K and Microsphere M, or to Microsphere M. A prepreg and a cylindrical fiber reinforced composite material were prepared. The resulting epoxy resin composition had excellent compressive fracture nominal strains of 66.6 and 65.8%. The impregnation property and cylindrical formability of the prepreg were also excellent, and the torsional strength of the cylindrical fiber reinforced composite material was excellent at 3010 and 2970 N · m · deg.

Claims (9)

An epoxy resin composition comprising the following constituent elements [A], [B], and [C], wherein the constituent element [A] is selected from [A1] biphenyl, naphthalene, fluorene, dicyclopentadiene, and an oxazolidone ring look containing one or more epoxy resins having at least one skeleton component [C] is a component [a] with respect to 100 parts by weight of an epoxy resin composition that contains 3 to 35 parts by weight.
[A] Epoxy resin [B] Curing agent [C] p-tert-butylphenylglycidyl ether, hexahydrophthalic acid diglycidyl ester, diglycidylaniline, p-aminophenol type liquid epoxy compound, and aniline At least one reactive compound In 100% by weight of component [A], [A1] 5 to 50% by weight of at least one epoxy resin having at least one skeleton selected from biphenyl, naphthalene, fluorene, dicyclopentadiene, and oxazolidone ring is included , The epoxy resin composition according to claim 1 . The epoxy resin composition of Claim 1 or 2 whose average epoxy equivalent of all the epoxy resins is 230-400. The epoxy resin composition according to any one of claims 1 to 3, wherein the constituent element [B] contains dicyandiamide. The epoxy resin composition in any one of Claims 1-4 containing a urea compound as a hardening accelerator. Component [A] in 100 wt%, [A2] average epoxy equivalent weight of 1,000 to 10,000 epoxy resin is contained 3 to 60 wt%, epoxy resin composition according to any one of claims 1 to 5. 7. The composition according to claim 1, wherein 0.1 to 10 parts by weight of at least one thermoplastic resin selected from a polyvinyl acetal resin and polymethyl methacrylate is included with respect to 100 parts by weight of the component [A]. The epoxy resin composition described in 1. A prepreg comprising reinforcing fibers and the epoxy resin composition according to claim 1 . A fiber-reinforced composite material obtained by curing the prepreg according to claim 8 .