JP2017101227A - Epoxy resin composition, and molding, prepreg and fiber-reinforced plastic prepared therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition which can form fiber-reinforced plastic having excellent mechanical properties, particularly a fiber-reinforced plastic tubular molding having high fracture strength.SOLUTION: An epoxy resin composition comprises the following components (A), (B), (C) and (D): component (A): oxazolidone skeleton-containing epoxy resin, component (B): epoxy resin other than component (A), component (C): curing agent, and component (D): cellulose nanofiber.SELECTED DRAWING: None

Description

  The present invention relates to an epoxy resin composition, and a molded article, prepreg and fiber reinforced plastic using the same, and is suitably used for sports / leisure use, general industrial use, aircraft material use, and the like. .

  BACKGROUND ART Fiber reinforced plastics, which are one of fiber reinforced composite materials, are widely used from sports / leisure applications to industrial applications such as automobiles and aircrafts because of their light weight, high strength, and high rigidity.

  As a method for producing a fiber reinforced plastic, there is a method of using an intermediate material obtained by impregnating a matrix resin into a reinforcing material made of long fibers (continuous fibers) such as reinforcing fibers, that is, a prepreg. According to this method, there is an advantage that the content of the reinforcing fiber of the fiber reinforced plastic can be easily managed and the content can be designed to be higher.

  Due to the need for weight reduction, carbon fibers excellent in specific strength and specific elastic modulus are often used as reinforcing fibers, and epoxy resins excellent in adhesion to carbon fibers are used as matrix resins.

  However, the epoxy resin generally has a cured product that is brittle and tends to have low toughness. Therefore, improvement of fracture toughness and rigidity of the fiber-reinforced plastic has been a technical problem. Therefore, in recent years, studies have been made to improve the nanofiller by dispersing it in a matrix.

  As this nanofiller, in particular, cellulose nanofibers derived from nature have attracted attention, and fiber reinforced composite materials suitable for sports equipment, which have improved fatigue fracture and impact properties by using this, are known. (See Patent Documents 1 and 2). Improvements in cellulose nanofibers are also being studied. For example, composite materials using cellulose nanofibers that have been subjected to various chemical treatments or cellulose nanofibers that have been refined in a defibrated resin without surface treatment are also known. (See Patent Documents 3 and 4).

JP 2011-148214 A JP 2010-24413 A Japanese Patent Laying-Open No. 2015-48375 Japanese Patent No. 5477516

However, none of Patent Documents 1 to 4 has sufficiently studied a matrix resin that is indispensable for the expression of performance as a fiber-reinforced plastic.
In Patent Document 1, details of the epoxy resin composition used as a matrix resin are not disclosed. Patent Documents 2 to 4 describe examples in which various epoxy resin compositions are used as a matrix resin, but fiber reinforced plastics using these are not particularly sufficient in bending strength.

  The present invention has been made in view of the above background. By using a specific epoxy resin composition containing cellulose nanofibers as a matrix resin, a fiber-reinforced plastic having excellent mechanical properties can be obtained. It is what I found. INDUSTRIAL APPLICABILITY The present invention relates to an epoxy resin composition capable of obtaining excellent breaking strength particularly when applied to a tubular composite material, a prepreg using the resin composition, and a fiber formed using the prepreg. It provides reinforced plastic.

  As a result of intensive studies, the present inventors have found that by using an epoxy resin having a specific structure, the above problems can be solved and a fiber-reinforced plastic having a desired performance can be provided, and the present invention has been achieved.

That is, the present invention relates to the following.
[1] An epoxy resin composition comprising the following components (A), (B), (C) and (D).
Component (A): Oxazolidone skeleton-containing epoxy resin Component (B): Epoxy resin other than component (A) Component (C): Curing agent Component (D): Cellulose nanofiber [2] The component (B) is an epoxy equivalent. The epoxy resin composition according to [1], wherein is an epoxy resin having 350 or more and / or an epoxy resin having an epoxy equivalent of less than 350.
[3] The epoxy resin composition according to [1] or [2], wherein the curing agent (C) is at least one selected from dicyandiamide, ureas, imidazoles, and aromatic amines.
[4] The epoxy resin composition according to any one of [1] to [3], wherein the component (A) is contained in an amount of 5 parts by weight or more and 80 parts by weight or less based on 100 parts by weight of the total epoxy resin.
[5] The epoxy resin composition according to any one of [1] to [4], wherein the component (B) is contained in an amount of 20 parts by mass or more and 95 parts by mass or less in 100 parts by mass of all epoxy resins.
[6] In any one of [1] to [5], the component (D) is included in an amount of 0.1 to 15 parts by mass with respect to 100 parts by mass of the total epoxy resin included in the epoxy resin composition of the present invention. The epoxy resin composition as described.
[7] The epoxy resin composition according to any one of [1] to [6], wherein the cured product has a bending strength of 135 MPa or more, an elastic modulus of 3.3 GPa or more, and a breaking elongation of 8.5% or more. object.
[8] The epoxy resin composition according to any one of [1] to [7], further including a thermoplastic resin as the component (E).
[9] The epoxy resin composition according to [8], including 1 to 20 parts by mass of the component (E) with respect to 100 parts by mass of the total epoxy resin.
[10] A molded article comprising a cured product of the epoxy resin composition according to any one of [1] to [9].
[11] A prepreg in which a reinforcing fiber is impregnated with the epoxy resin composition according to any one of [1] to [9].
[12] A fiber-reinforced plastic comprising a cured product of the epoxy resin composition according to any one of [1] to [9] and a reinforcing fiber.
[13] The fiber-reinforced plastic according to [12], wherein the interlayer shear strength is 90 MPa or more.
[14] The fiber-reinforced plastic according to [12] or [13], which is tubular.

  By using the epoxy resin composition of the present invention as a matrix resin of a fiber reinforced plastic, a fiber reinforced plastic having excellent mechanical properties can be obtained. In particular, by using the epoxy resin composition of the present invention, excellent fracture strength can be obtained in a fiber reinforced plastic of a tubular body.

Hereinafter, the present invention will be described in detail.
In the present invention, “epoxy resin” means a compound having two or more epoxy groups in one molecule.
The term “epoxy resin composition” means a composition containing an epoxy resin, a curing agent, a curing accelerator, and optionally a thermoplastic resin and other additives. That is, the epoxy resin composition of the present invention includes the component (A), the component (B), the component (C), and the component (D), and may further include the component (E) and other additives.
In the present invention, a cured product obtained by curing the epoxy resin composition is referred to as a “resin cured product”, and among them, a plate-shaped cured product is particularly referred to as a “resin plate”.

<Component (A)>
Component (A) is an oxazolidone skeleton-containing epoxy resin.
The oxazolidone skeleton-containing epoxy resin improves the workability of the prepreg containing the epoxy resin composition containing the epoxy resin composition at room temperature, and the elastic modulus, heat resistance, reinforcing fiber and component (D) of the cured product of the epoxy resin composition. Increase adhesion with.

  The oxazolidone ring structure is formed by an addition reaction between an isocyanate group and an epoxy group. The production method of the oxazolidone skeleton-containing epoxy resin in the present invention is not particularly limited. For example, by reacting an isocyanate compound and an epoxy resin having a biphenyl skeleton in the presence of an oxazolidone ring-forming catalyst, it is almost the theoretical amount. Can be obtained. It is preferable that the isocyanate compound and the epoxy resin are reacted in an equivalent ratio of 1: 2 to 1:10. When the ratio of the two is in the above range, the heat resistance and water resistance of the cured epoxy resin are better. There is a tendency. In the present invention, various isocyanate compounds can be used as raw materials, but in order to incorporate the oxazolidone ring structure into the skeleton of the epoxy resin, an isocyanate compound having a plurality of isocyanate groups is preferable. Moreover, in order for the hardened | cured material of the epoxy resin composition containing the said component (A) to have high heat resistance, the diisocyanate which has a rigid structure is preferable.

  Specific examples of the isocyanate compound used as the raw material include, for example, methane diisocyanate, butane-1,1-diisocyanate, ethane-1,2-diisocyanate, butane-1,2-diisocyanate, transvinylene diisocyanate, propane-1,3- Diisocyanate, butane-1,4-diisocyanate, 2-butene-1,4-diisocyanate, 2-methylbutene-1,4-diisocyanate, 2-methylbutane-1,4-diisocyanate, pentane-1,5-diisocyanate, 2, 2-dimethylpentane-1,5-diisocyanate, hexane-1,6-diisocyanate, heptane-1,7-diisocyanate, octane-1,8-diisocyanate, nonane-1,9-diisocyanate, decane-1,10- Isocyanate, dimethylsilane diisocyanate, diphenylsilane diisocyanate, ω, ω′-1,3-dimethylbenzene diisocyanate, ω, ω′-1,4-dimethylbenzene diisocyanate, ω, ω′-1,3-dimethylcyclohexane diisocyanate, ω , Ω′-1,4-dimethylcyclohexane diisocyanate, ω, ω′-1,4-dimethylnaphthalene diisocyanate, ω, ω′-1,5-dimethylnaphthalene diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1, 4-diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-phenylene diisocyanate, 1,4-pheny Diisocyanate, 1-methylbenzene-2,4-diisocyanate, 1-methylbenzene-2,5-diisocyanate, 1-methylbenzene-2,6-diisocyanate, 1-methylbenzene-3,5-diisocyanate, diphenyl ether-4 , 4′-diisocyanate, diphenyl ether-2,4′-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, biphenyl-4,4′-diisocyanate, 3,3′-dimethylbiphenyl-4, 4'-diisocyanate, 2,3'-dimethoxybisphenyl-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxydiphenylmethane-4,4'-diisocyanate, 4,4'- Zimetoki Bifunctional isocyanate compounds such as sidiphenylmethane-3,3′-diisocyanate, norbornene diisocyanate, diphenylsulfite-4,4′-diisocyanate, diphenylsulfone-4,4′-diisocyanate; polymethylene polyphenylisocyanate, triphenylmethanetri Polyfunctional isocyanate compounds such as isocyanate, tris (4-phenylisocyanatethiophosphate) -3,3 ′, 4,4′-diphenylmethanetetraisocyanate; multimers such as dimers and trimers of the isocyanate compounds, alcohols, Examples thereof include, but are not limited to, blocked isocyanates and bisurethane compounds masked with phenol. Two or more of these isocyanate compounds may be used in combination.

  Among the above isocyanate compounds, since heat resistance tends to be improved, it is preferably a bifunctional or trifunctional isocyanate compound, more preferably a bifunctional isocyanate compound, still more preferably isophorone, benzene, toluene, diphenylmethane, naphthalene, norbornene, It is a bifunctional isocyanate compound having a skeleton selected from polymethylene polyphenylene polyphenyl and hexamethylene. When the number of functional groups of the isocyanate compound is too large, the storage stability of the epoxy resin composition tends to decrease, and when it is too small, the heat resistance of the cured product of the epoxy resin composition tends to decrease.

  In addition, various epoxy resins can be used as the epoxy resin as a raw material for the component (A). In order to efficiently incorporate the oxazolidone ring structure into the skeleton of the epoxy resin, epoxy groups are present at both ends of the molecule. An epoxy resin having is preferred. Specific examples of the epoxy resin used as a raw material for the component (A) include, for example, bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetramethylbisphenol AD, tetramethylbisphenol S, Epoxy resins derived from dihydric phenols such as tetrabromobisphenol A; 1,1,1-tris (4-hydroxyphenyl) methane, 1,1,1- (4-hydroxyphenyl) ethane, 4,4- [1 -Epoxy resins derived from tris (glycidyloxyphenyl) alkanes such as [4- [1- (4-hydroxyphenyl) -1-methylethyl] phenyl] ethylidene] bisphenol; phenol novolac, cresol novolac, bisphenol A Rack and epoxy resins derived from novolaks, and the like, but not particularly limited thereto. As the epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin and the like are particularly preferable because the viscosity of the component (A) is not excessively increased.

  As the isocyanate compound, a bifunctional isocyanate having a toluene skeleton such as tolylene diisocyanate (for example, 1-methylbenzene-2,4-diisocyanate, 1-methylbenzene-2,5-diisocyanate, 1-methylbenzene-2,6 -An addition reaction product obtained by mixing and reacting one molecule of diisocyanate, 1-methylbenzene-3,5-diisocyanate) and two molecules of bisphenol A diglycidyl ether as an epoxy resin is the workability of the prepreg at room temperature. It is particularly preferable for improving the heat resistance of the cured product of the epoxy resin composition.

As commercially available epoxy resins having an oxazolidone ring structure (component (A)), AER4152, AER4151, LSA3301, LSA2102 (all trade names, manufactured by Asahi Kasei E-Materials Co., Ltd.) and ACR1348 (trade names, stocks) ADE852, DER 852, DER 858 (trade name, manufactured by DOW), TSR-400 (trade name, manufactured by DIC), and the like. All of these are preferably used in the present invention, but AER 4152 and TSR-400 are used. Particularly preferred.
As said component (A), you may use together 2 or more types of above epoxy resins.

  It is preferable that content of a component (A) is 5 to 80 mass parts in 100 mass parts of all the epoxy resins contained in the epoxy resin composition of this invention. If content of a component (A) is 5 mass parts or more, it exists in the tendency which can obtain the resin cured material excellent in heat resistance and mechanical physical property. More preferably, it is 7 mass parts or more, More preferably, it is 10 mass parts or more. On the other hand, if the content of the component (A) is 80 parts by mass or less, it is possible to obtain a prepreg excellent in tack and drapability and to obtain a cured resin product having high fracture toughness and no voids. is there. More preferably, it is 75 mass parts or less, More preferably, it is 70 mass parts or less. As for content of a component (A), it is more preferable that it is the range of 7-75 mass parts, and it is especially preferable that it is the range of 10-70 mass parts.

<Component (B)>
Component (B) is an epoxy resin having an epoxy equivalent other than component (A) of 350 or more and / or an epoxy resin having an epoxy equivalent of less than 350.

  The epoxy resin having an epoxy equivalent of 350 or more and / or the epoxy resin having an epoxy equivalent of less than 350 is not particularly limited, but a bifunctional or higher functional epoxy resin is preferably used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, modified epoxy resin, phenol novolac type epoxy resin, Cresol novolac type epoxy resin, trisphenolmethane type epoxy resin, glycidylamine type epoxy resin such as tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, and other than the above such as tetrakis (glycidyloxyphenyl) ethane and tris (glycidyloxy) methane Glycidyl ether type epoxy resins, epoxy resins modified with these, phenol aralkyl type epoxy resins and the like. As the bifunctional epoxy resin, a bisphenol A type epoxy resin or a bisphenol F type epoxy resin is particularly preferably used from the viewpoint of the viscosity and mechanical properties of the epoxy resin composition. Tri- or higher functional epoxy resins provide better strength, elastic modulus, and heat resistance, so para- and meta-type triglycidylaminophenol-type epoxy resins, tetraglycidyldiaminodiphenylmethane-type epoxy resins, and phenol novolacs Type epoxy resin and cresol novolac type epoxy resin are particularly preferably used. When roughly classified, an epoxy resin having an epoxy equivalent of 350 or more, more preferably 450 or more can mainly improve toughness, and an epoxy resin having an epoxy equivalent of less than 350 mainly improves strength, elastic modulus, and heat resistance. be able to.

  The epoxy resin is for improving workability by adjusting the viscoelasticity of the epoxy resin composition of the present invention when not cured, or for improving the strength, elastic modulus, toughness, and heat resistance of the cured resin. 1 type may be used independently and may be used in combination of 2 or more type.

It is preferable that content of a component (B) shall be 20 to 95 mass parts in 100 mass parts of all the epoxy resins contained in the epoxy resin composition of this invention. If content of a component (B) is 20 mass parts or more, it exists in the tendency which can obtain the resin cured | curing material in which intensity | strength, an elasticity modulus, fracture toughness, etc. were compatible. More preferably, it is 25 parts by mass or more. On the other hand, if content of a component (B) is 95 mass parts or less, it exists in the tendency which can obtain the resin cured material excellent in heat resistance and mechanical physical property. More preferably, it is 90 mass parts or less, More preferably, it is 85 mass parts or less.
Moreover, it is preferable that the epoxy resin whose epoxy equivalent is 350 or more shall be 5 to 60 mass parts in a component (B). If the epoxy resin having an epoxy equivalent of 350 or more is 5 parts by mass or more, suitable toughness and impact resistance tend to be imparted to the cured resin. If it is 60 mass parts or less, it exists in the tendency which can give suitable elasticity modulus and heat resistance to resin cured material. More preferably, it is 10 to 55 mass parts.
Furthermore, the epoxy resin having an epoxy equivalent of less than 350 is preferably 15 parts by mass or more and 90 parts by mass or less in the component (B). If the epoxy resin having an epoxy equivalent of less than 350 is 15 parts by mass or more, the epoxy resin composition can be provided with an appropriate viscosity, and the resin cured product should be provided with an appropriate elastic modulus and heat resistance. There is a tendency to be able to. If it is 90 mass parts or less, it exists in the tendency which can provide suitable toughness and impact resistance to a resin cured material. More preferably, it is 20 to 85 mass parts.

Moreover, you may use a commercial item as a component (B).
Examples of commercially available epoxy resins include jER807 (epoxy equivalent 170 g / eq), jER4004P (epoxy equivalent 908 g / eq), jER4005P (epoxy equivalent 1070 g / eq), jER4007P (epoxy equivalent 2270 g / eq), jER4010P (epoxy equivalent 4400 g). / Eq), jER828 (epoxy equivalent 189 g / eq), jER1001 (epoxy equivalent 475 g / eq), jER1002 (epoxy equivalent 650 g / eq), jER1004 (epoxy equivalent 925 g / eq), jER1007 (epoxy equivalent 1975 g / eq), jER1009 (Epoxy equivalent 2850 g / eq), jER604 (Epoxy equivalent 120 g / eq), jER630 (Epoxy equivalent 98 g / eq), jER1032H60 (E Xy equivalent 169 g / eq), jER152 (epoxy equivalent 175 g / eq), jER154 (epoxy equivalent 178 g / eq), YX-7700 (epoxy equivalent 273 g / eq), YX-4000 (epoxy equivalent 186 g / eq) (above, Mitsubishi YDF-2001 (epoxy equivalent 475 g / eq), YDF-2004 (epoxy equivalent 950 g / eq) (above, manufactured by KUKDO CHEMICAL); GAN (epoxy equivalent 125 g / eq), GOT (epoxy equivalent 135 g) / Eq), NC-2000 (epoxy equivalent 241 g / eq), NC-3000 (epoxy equivalent 275 g / eq) (Nippon Kayaku Co., Ltd.); YDPN-638 (epoxy equivalent 180 g / eq), TX-0911 (Epoxy equivalent 172 g / eq) (above Nippon Steel & Sumikin Chemical Co., Ltd.), Epon165 (epoxy equivalent 230 g / eq) (above, manufactured by Momentive Specialty Chemicals); MY-0500 (epoxy equivalent 110 g / eq), MY-0600 (epoxy equivalent 106 g / eq), ECN- 1299 (epoxy equivalent 230 g / eq) (manufactured by Huntsman Japan Ltd.); HP-4032 (epoxy equivalent 150 g / eq), HP-4700 (epoxy equivalent 162 g / eq), HP-7200 (epoxy equivalent 265 g / eq) (Above, manufactured by DIC Corporation) and the like, but are not limited thereto.

<Ingredient (C)>
Component (C) is a curing agent. As the curing agent used as the component (C), for example, dicyandiamide, ureas, imidazoles, aromatic amines, other amine-based curing agents, acid anhydrides, boron chloride amine complexes, etc. can be used. It is preferable to use at least one curing agent selected from dicyandiimide, ureas, imidazoles, and aromatic amines. Moreover, as a component (C), it is preferable to use a hardening | curing agent with a small average particle diameter. This is because the smaller the average particle size, the better the solubility of the curing agent in the epoxy resin during curing, and the mechanical properties of the resulting resin cured product and fiber reinforced plastic tend to be improved. . Further, even when the curing agent remains undissolved and remains in the cured resin or fiber reinforced plastic, it tends to be less likely to be a starting point for the destruction of the cured resin or fiber reinforced plastic.

  Since dicyandiamide has a high melting point and can suppress compatibility with an epoxy resin in a low temperature region, it is preferable to use it as a curing agent (C) because an epoxy resin composition having an excellent pot life tends to be obtained. In addition, it is preferable that the epoxy resin composition contains dicyandiamide as the curing agent (C) because the mechanical properties of the resin cured product tend to be improved.

The content of dicyandiamide in the epoxy resin composition of the present invention is such that the number of moles of active hydrogen of dicyandiamide is 0.4 to 1 times the total number of moles of epoxy groups contained in the epoxy resin contained in this epoxy resin composition. It is preferable that the amount is as follows. By setting the ratio to 0.4 times or more, a cured product having good heat resistance and good mechanical properties (that is, having high strength and elastic modulus) tends to be obtained. Moreover, by setting it as 1 times or less, it has the advantage that there exists a tendency for the hardened | cured material with favorable mechanical physical property (namely, excellent plastic deformation capability and impact resistance) to be obtained. Furthermore, by making the number of moles of active hydrogen of this dicyandiamide 0.5 to 0.8 times, the heat resistance of the resin cured product tends to be more excellent, which is more preferable.
Examples of commercially available dicyandiamide include, but are not limited to, DICY7 and DICY15 (manufactured by Mitsubishi Chemical Corporation).

  The ureas used as the component (C) have a dimethylureido group in the molecule, and are heated at a high temperature to produce an isocyanate group and dimethylamine, which are the epoxy groups of the component (A) and the component (B). In addition, there is no particular limitation as long as it activates the component (C) to be used in combination. For example, an aromatic dimethylurea in which a dimethylureido group is bonded to an aromatic ring, an aliphatic in which a dimethylureido group is bonded to an aliphatic compound Examples include dimethyl urea. Among these, aromatic dimethylurea is preferable in that the curing rate is high and the heat resistance and bending strength of the cured product tend to be high.

As the aromatic dimethylurea, for example, phenyldimethylurea, methylenebis (phenyldimethylurea), tolylenebis (dimethylurea) and the like are preferably used. Specific examples include 4,4′-methylenebis (phenyldimethylurea) (MBPDMU), 3-phenyl-1,1-dimethylurea (PDMU), 3- (3,4-dichlorophenyl) -1,1-dimethylurea. (DCMU), 3- (3-chloro-4-methylphenyl) -1,1-dimethylurea, 2,4-bis (3,3-dimethylureido) toluene (TBDMU), m-xylylene diisocyanate and dimethylamine And dimethylurea obtained from the above. Among these, DCMU, MBPDMU, TBDMU, and PDMU are more preferably used from the viewpoint of imparting curing acceleration ability and improving the mechanical properties of the cured resin.
These may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of the aliphatic dimethylurea include dimethylurea obtained from isophorone diisocyanate and dimethylamine, and dimethylurea obtained from hexamethylene diisocyanate and dimethylamine.

As ureas, commercially available products may be used.
As a commercial item of DCMU, DCMU-99 (above, Hodogaya Chemical Co., Ltd. product) etc. are mentioned, for example, However, It is not limited to these.
Examples of commercially available products of MBPDMU include Technicure MDU-11 (above, manufactured by A & C Catalysts); Omicure 52 (above, manufactured by PTI Japan Ltd.), and the like. It is not something.
Examples of commercially available products of PDMU include, but are not limited to, Omicure 94 (above, manufactured by PTI Japan).
Examples of commercially available products of TBDMU include Omicure 24 (above, PTI Japan Ltd.), U-CAT 3512T (San Apro Co., Ltd.) and the like. is not.
Examples of commercially available aliphatic dimethylurea include, but are not limited to, U-CAT 3513N (manufactured by San Apro).

  1-15 mass parts is preferable with respect to 100 mass parts of all the epoxy resins contained in the epoxy resin composition of this invention, and, as for content of ureas, 2-10 mass parts is more preferable. When the urea content is 1 part by mass or more, the epoxy resin contained in the epoxy resin composition is sufficiently cured and cured to tend to increase mechanical properties and heat resistance. On the other hand, if the urea content is 15 parts by mass or less, the toughness of the cured resin product tends to be kept high.

The imidazoles used as the component (C) may be imidazoles, and imidazole adducts, clathrate imidazoles, microcapsule imidazoles, imidazole compounds coordinated with stabilizers, and the like can also be used.
These have a nitrogen atom having an unshared electron pair in their structure, which activates the epoxy group of component (A) or component (B), and also activates component (C) to be used in combination. Can be cured, and curing and curing can be promoted.

  Specific examples of imidazole include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, 2-phenyl-4. -Methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2- Undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazolium trimellitate, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2- Feni Imidazolium trimellitate, 2,4-diamino-6- (2′-methylimidazolyl- (1 ′))-ethyl-s-triazine, 2,4-diamino-6- (2′-undecylimidazolyl- ( 1 ′))-ethyl-s-triazine, 2,4-diamino-6- (2′-ethyl-4-methylimidazolyl- (1 ′))-ethyl-s-triazine, 2,4-diamino-6 (2′-methylimidazolyl- (1 ′))-ethyl-s-triazine / isocyanuric acid adduct, 2-phenylimidazole / isocyanuric acid adduct, 2-methylimidazole / isocyanuric acid adduct, 1-cyanoethyl-2- Phenyl-4,5-di (2-cyanoethoxy) methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl -5-hydroxymethyl imidazole, and the like, but not limited thereto.

  Adduct treatment, inclusion treatment with different molecules, microcapsule treatment, or imidazole coordinated with a stabilizer is a modification of the imidazole. These are cured by adduct treatment with imidazole, inclusion treatment with different molecules, microcapsule treatment, or by degrading the activity by coordinating a stabilizer, while exhibiting excellent pot life in a low temperature region, and curing and hardening acceleration High ability.

Moreover, you may use a commercial item as imidazoles.
Examples of commercially available imidazoles include 2E4MZ, 2P4MZ, 2PZ-CN, C11Z-CNS, C11Z-A, 2MZA-PW, 2MA-OK, 2P4MHZ-PW, 2PHZ-PW (manufactured by Shikoku Kasei Kogyo Co., Ltd.). However, it is not limited to these.

  Examples of commercially available imidazole adducts include PN-50, PN-50J, PN-40, PN-40J, PN-31, and PN-23, which have a structure in which an imidazole compound is ring-opened and added to an epoxy group of an epoxy resin. PN-H (manufactured by Ajinomoto Fine Techno Co., Ltd.) and the like, but are not limited thereto.

  Examples of the commercially available clathrate imidazole include TIC-188, KM-188, HIPA-2P4MHZ, NIPA-2P4MHZ, TEP-2E4MZ, HIPA-2E4MZ, NIPA-2E4MZ (manufactured by Nippon Soda Co., Ltd.) and the like. However, it is not limited to these.

  Examples of commercially available microcapsule type imidazole include NOVACURE HX3721, HX3722, HX3742, and HX3748 (above, manufactured by Asahi Kasei E-Materials Co., Ltd.); LC-80 (above, manufactured by A & C Catalysts), and the like. It is not limited.

  Moreover, the imidazole compound coordinated with the stabilizer is, for example, cure duct P-0505 (bisphenol A diglycidyl ether / 2-ethyl-4-methylimidazole adduct) which is an imidazole adduct manufactured by Shikoku Kasei Kogyo Co., Ltd. It can be prepared by combining L-07N (epoxy-phenol-borate ester compound) which is a stabilizer manufactured by Shikoku Kasei Kogyo Co., Ltd. The same effect can be obtained by using imidazole compounds such as various imidazoles and imidazole adducts mentioned above instead of the cure duct P-0505. As the imidazole compound before the stabilizer is coordinated, those having low solubility in an epoxy resin are preferably used, and in this respect, cure duct P-0505 is preferred.

  1-15 mass parts is preferable with respect to 100 mass parts of all the epoxy resins contained in the epoxy resin composition of this invention, and, as for content of imidazoles, 2-10 mass parts is more preferable. If content of imidazole is 1 mass part or more, it exists in the tendency for the hardening of a epoxy resin contained in an epoxy resin composition, hardening acceleration | stimulation effect | action, and heat resistance to fully be acquired. On the other hand, if the content of imidazoles is 15 parts by mass or less, a cured resin having excellent mechanical properties tends to be obtained.

  Examples of aromatic amines used as the component (C) include 3,3′-diisopropyl-4,4′-diaminodiphenylmethane, 3,3′-di-t-butyl-4,4′-diaminodiphenylmethane, 3,3′-diethyl-5,5′-dimethyl-4,4′-diaminodiphenylmethane, 3,3′-diisopropyl-5,5′-dimethyl-4,4′-diaminodiphenylmethane, 3,3′-di -T-butyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetraethyl-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl-5,5 '-Diethyl-4,4'-diaminodiphenylmethane, 3,3'-di-t-butyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, 3,3', , 5′-tetraisopropyl-4,4′-diaminodiphenylmethane, 3,3′-di-t-butyl-5,5′-diisopropyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5 ′ -Tetra-t-butyl-4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylene diene Examples include, but are not limited to, amine and diethyltoluenediamine. Among these, it is preferable to use 4,4′-diaminodiphenyl sulfone and 3,3′-diaminodiphenyl sulfone, which are excellent in heat resistance and elastic modulus, and are capable of obtaining a cured product in which the linear expansion coefficient and the decrease in heat resistance due to moisture absorption are small. . 4,4'-diaminodiphenylsulfone is also preferable in that the tack life of the prepreg can be maintained for a long period. Although 3,3′-diaminodiphenylsulfone is inferior to 4,4′-diaminodiphenylsulfone in the tack life of the prepreg and the heat resistance of the cured product, it is preferable because the elastic modulus and toughness of the cured product can be increased. . Further, it is preferable to add 4,4'-diaminodiphenylsulfone and 3,3'-diaminodiphenylsulfone at the same time because the heat resistance and elastic modulus of the cured product can be easily adjusted. These aromatic amines may be used singly or may be appropriately mixed and used.

  The compounding amount of aromatic amines, particularly diaminodiphenylsulfone, is 0.5 to 1.5 times the number of epoxy equivalents of all epoxy resins contained in the epoxy resin composition of the present invention. It is preferable that it is 2 times, and it is more preferable that it is 0.6 to 1.4 times. By making the compounding quantity of these epoxy resin hardening | curing agents 0.5 to 1.5 times, it exists in the tendency which can make the elasticity modulus, toughness, and heat resistance of a cured epoxy resin into a favorable range.

Moreover, a commercial item may be used for aromatic amines.
Examples of commercially available 4,4′-diaminodiphenylsulfone include Seikacure S (manufactured by Wakayama Seika Kogyo Co., Ltd.) and SumiCure S (manufactured by Sumitomo Chemical Co., Ltd.). Examples thereof include, but are not limited to, 3,3′-DAS (manufactured by Mitsui Chemicals Fine). Other commercially available aromatic amines include MDA-220 (manufactured by Mitsui Chemicals), “jER Cure (registered trademark)” W (manufactured by Japan Epoxy Resin Co., Ltd.), Lonzacure (registered trademark) M-DEA. (Manufactured by Lonza), "Lonzacure (registered trademark)" M-DIPA (manufactured by Lonza), "Lonzacure (registered trademark)" M-MIPA (manufactured by Lonza) and "Lonzacure (registered trademark) “DETDA 80 (manufactured by Lonza Co., Ltd.)” and the like are exemplified, but not limited thereto.

  Examples of other amine curing agents that can be used as the component (C) include metaphenylenediamine, diaminodiphenylmethane, metaxylenediamine, isophoronediamine, and triethylenetetramine.

  Examples of the acid anhydride that can be used as the component (C) include hydrogenated methyl nadic acid anhydride and methyl hexahydrophthalic acid anhydride.

<Component (D)>
Cellulose nanofibers that can be used in the present invention as the component (D) are obtained by defibrating and / or refining various celluloses, and are blended into the epoxy resin composition of the present invention to destroy the cured resin. Strength can be improved.

  The cellulose in the present invention may be any cellulose as long as it can be used as a defibrating material and / or a fine material, such as pulp, cotton, paper, regenerated cellulose fibers such as rayon, cupra, polynosic acetate, bacteria-producing cellulose, sea squirt, etc. Animal-derived cellulose and the like can be used. Further, these celluloses may be obtained by chemically modifying the surface as necessary.

  As the pulp, both wood pulp and non-wood pulp can be suitably used. Wood pulp includes mechanical pulp and chemical pulp, and chemical pulp having a low lignin content is preferred. Chemical pulp includes sulfide pulp, kraft pulp, alkaline pulp and the like, and any of them can be suitably used. As non-wood pulp, any of straw, bagasse, kenaf, bamboo, straw, straw, flax, etc. can be used.

Cotton is a plant mainly used for clothing fibers, and cotton, cotton fibers, and cotton cloth can be used.
Paper is obtained by removing fibers from pulp, and used paper such as newspaper, waste milk pack, and copied paper can be suitably used.

  In addition, cellulose powder having a certain particle size distribution obtained by crushing cellulose may be used as cellulose as a refining material. KC Flock (registered trademark) manufactured by Nippon Paper Chemicals Co., Ltd. Registered trademark), Avicel (registered trademark) manufactured by FMC, and the like.

Cellulose nanofibers that can be used in the present invention may be modified to enhance functionality. In the present invention, the cellulose nanofibers are prepared by defibrating and / or refining cellulose to produce cellulose nanofibers, and then adding a modifying compound to react with the cellulose nanofibers (that is, the surface of the cellulose nanofibers). It may be a modified cellulose nanofiber obtained by chemically modifying a hydroxyl group with a modifying group and reducing the hydroxyl group).
As a compound to be modified, a functional group such as an alkyl group, an acyl group, an acylamino group, a cyano group, an alkoxy group, an aryl group, an amino group, an aryloxy group, a silyl group, or a carboxyl group is chemically bonded to the cellulose nanofiber. And the like. By chemical modification, strong adhesion due to hydrogen bonding between cellulose nanofibers can be prevented, so that it can be easily dispersed in a polymer material and a good interface bond can be formed. Moreover, since it has heat resistance by being chemically modified, heat resistance can be imparted to other materials by mixing with other materials. The proportion of the total hydroxyl groups in the cellulose nanofibers that are chemically modified by the modifying group is preferably 0.01% to 50%, and more preferably 0.1% to 45%.

  Further, the cellulose nanofibers may be modified so that the compound to be modified is physically adsorbed on the cellulose nanofibers without being chemically bonded. Examples of the physically adsorbing compound include a surfactant and the like, and any of anionic, cationic and nonionic properties may be used, but it is preferable to use a cationic surfactant.

  The cellulose nanofibers preferably have an average fiber width of 2 to 1000 nm determined by observation with an electron microscope. The average fiber width of the cellulose nanofiber is more preferably 2 to 700 nm, and further preferably 2 to 500 nm. If the average fiber width of the cellulose nanofiber exceeds the upper limit, it becomes difficult to obtain the characteristics (high strength, high rigidity, high dimensional stability, and high dispersibility when combined with resin) as the cellulose nanofiber. Become. When the average fiber width of the cellulose nanofibers is less than the lower limit value, the cellulose nanofibers are dissolved in the dispersion medium as cellulose molecules, so that characteristics (high strength, high rigidity, high dimensional stability) as cellulose nanofibers can be obtained. It becomes difficult.

  The number average fiber diameter of the fine cellulose fibers can be measured and determined by observing with a scanning electron microscope SEM, a transmission electron microscope TEM or the like. For example, after removing water, organic solvent, etc. from the fine cellulose fiber dispersion by drying, a line is drawn on the diagonal line of the SEM photograph magnified 30,000 times, and 12 fibers are randomly extracted in the vicinity thereof, and the thickest The average of 10 measured values obtained by removing the fibers and the thinnest fibers can be used as the number average fiber diameter.

  The average fiber length of the cellulose nanofiber is preferably 0.05 to 10 μm, and more preferably 0.05 to 8 μm. If average fiber length is more than the said lower limit, it exists in the tendency for the intensity | strength improvement effect at the time of mix | blending a cellulose nanofiber with resin to be fully acquired. If average fiber length is below the said upper limit, it exists in the tendency for the mixability at the time of mix | blending a cellulose nanofiber with resin to become more favorable. The average fiber length can be determined, for example, by analyzing an electron microscope observation image used when measuring the average fiber width.

It is preferable that the cellulose nanofiber can be used as a master batch dispersed in a matrix resin such as an epoxy resin.
As an epoxy resin master batch of cellulose nanofiber, YL7883-3, YL7883-5, YL7883-10, YL7883-15, YL7923-3, YL7923-5, YL7923-10, YL7923-15, YL7951-10 (and above, Mitsubishi Chemical) Etc.) are available, but are not limited to these. In addition, although the cellulose nanofiber containing epoxy resin masterbatch was used in this application, the component (D) is cellulose nanofiber itself and the epoxy resin was included in the component (B).

  As for content of the cellulose nanofiber which is a component (D), 0.1-15 mass parts is preferable with respect to 100 mass parts of all the epoxy resins contained in the epoxy resin composition of this invention. If content of a component (D) is 0.1 mass part or more, it exists in the tendency which can improve the fracture strength of resin cured material. More preferably, it is 0.3 mass part or more, More preferably, it is 0.5 mass part or more. Moreover, if content of a component (D) is 15 mass parts or less, since it exists in the tendency for the viscoelasticity at the time of uncured of an epoxy resin composition to become an appropriate range, it is preferable. More preferably, it is 13 parts by mass or less, and even more preferably, 10 parts by mass or less.

<Component (E)> A thermoplastic resin is a component in the epoxy resin composition of this invention as needed for the purpose of resin flow control at the time of shaping | molding of the epoxy resin composition of this invention, and the provision of toughness to a resin cured material. It can mix | blend as (E).

Examples of the thermoplastic resin include polyamide, polyester, polycarbonate, polyether sulfone, polyphenylene ether, polyphenylene sulfide, polyether ether ketone, polyether ketone, polyimide, polytetrafluoroethylene, polyether, polyolefin, liquid crystal polymer, polyarylate, Examples thereof include polysulfone, polyacrylonitrile styrene, polystyrene, polyacrylonitrile, polymethyl methacrylate, ABS, AES, ASA, polyvinyl chloride, polyvinyl formal resin, phenoxy resin, and block polymer. Among these, phenoxy resin and polyvinyl formal resin are preferable because of excellent resin flow controllability and the like. Phenoxy resin is also preferable in terms of enhancing the flame retardancy of the cured resin, and polyvinyl formal resin can easily control the prepreg tack obtained to a suitable range without damaging the heat resistance of the cured product. It is also preferable from the viewpoint of improving the adhesion between the fiber and the epoxy resin composition. Moreover, a block polymer is preferable at the point which the toughness and impact resistance of a resin cured material improve more.
These may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of the phenoxy resin include, but are not limited to, YP-50, YP-50S, YP70, ZX-1356-2, FX-316 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) and the like.

  As the polyvinyl formal resin, vinylec (registered trademark) K (average molecular weight: 59000), vinylec L (average molecular weight: 66000), vinylec H (average molecular weight: 73000), vinylec E (average molecular weight: 126000) (above JNC Corporation) But not limited to these.

  In addition, when the resin cured product requires heat resistance exceeding 180 ° C., polyethersulfone or polyetherimide is preferably used. Specifically, as polyether sulfone, SUMIKAEXCEL (registered trademark) 3600P (average molecular weight: 16400), SUMIKAEXCEL 5003P (average molecular weight: 30000), SUMIKAEXCEL 5200P (average molecular weight: 35000), SUMIKAEXCEL 7600P (average molecular weight) : 45300) (above, manufactured by Sumitomo Chemical Co., Ltd.), Ultrason E2020P (average molecular weight: 48000) (above, manufactured by BASF), Virantage VW-10200 (average molecular weight: 46500), Virantage VW-10700 (average molecular weight: 21000) (Above, manufactured by Solvay). Examples of the polyetherimide include ULTEM1000 (average molecular weight: 32000), ULTEM1010 (average molecular weight: 32000), ULTEM1040 (average molecular weight: 20000) (which is manufactured by GE Plastics Co., Ltd.) and the like. It is not something.

  As block polymers, Nanostrength M52, Nanostrength M52N, Nanostrength M22, Nanostrength M22N, Nanostrength 123, Nanostrength 250, Nanostrength 123, Nanostrength M12, Nanostrength 123 TPAE-23, TPAE-31, TPAE-38, TPAE-63, TPAE-100, PA-260 (manufactured by T & K TOKA, Inc.) and the like can be mentioned, but are not limited thereto.

  1-20 mass parts is preferable with respect to 100 mass parts of all the epoxy resins contained in the epoxy resin composition of this invention, and, as for content of a component (E), 2-15 mass parts is more preferable. If content of a component (E) is 1 mass part or more, it exists in the tendency for resin flow control and a physical-property improvement effect to be exhibited favorably. On the other hand, when the content of the component (E) is 20 parts by mass or less, the heat resistance and mechanical properties of the resin cured product, and the prepreg tack and drape properties tend to be easily maintained.

<Optional component>
The epoxy resin composition of the present invention may contain various known additives as long as it does not impair the effects of the present invention.
Additives include elastomers, thermoplastic elastomers, flame retardants (eg phosphorus-containing epoxy resins, red phosphorus, phosphazene compounds, phosphates, phosphate esters, etc.), silicone oils, wetting and dispersing agents, antifoaming agents, defoaming Agents, natural waxes, synthetic waxes, release salts such as metal salts of straight-chain fatty acids, acid amides, esters, paraffins, crystalline silica, fused silica, calcium silicate, alumina, calcium carbonate, talc, sulfuric acid Examples thereof include powders such as barium, metal oxides, metal hydroxides, inorganic fillers such as glass fibers and carbon fibers, colorants such as carbon black and bengara, and silane coupling agents. Furthermore, an ultraviolet absorber, a light stabilizer, a carbon nanotube, fullerene, etc. can also be mix | blended as needed.
These may be used individually by 1 type and may be used in combination of 2 or more type.

<Method for producing epoxy resin composition>
The epoxy resin composition of the present invention can be obtained, for example, by mixing the above-described components.
Examples of the method for mixing each component include a method using a mixer such as a three-roll mill, a planetary mixer, a kneader, a homogenizer, and a homodisper.

<Viscosity of epoxy resin composition>
The epoxy resin composition of the present invention can be used for production of a prepreg by impregnating a reinforcing fiber assembly, for example, as described later.

The viscosity of the epoxy resin composition at 30 ° C. is preferably 100 Pa · s or more, more preferably 300 Pa · s or more, and more preferably 500 Pa · s or more from the viewpoint of adjusting the tack of the prepreg surface to be obtained and workability. Is more preferable. The upper limit of the viscosity is preferably 1000000 Pa · s or less, more preferably 900000 Pa · s or less, and further preferably 800000 Pa · s or less.
Further, the viscosity of the epoxy resin composition at 60 ° C. is preferably 10 Pa · s or more, more preferably 20 Pa · s or more, and further preferably 30 Pa · s or more, from the viewpoint of the quality of the prepreg obtained. Further, from the viewpoint of impregnation into the reinforcing fiber aggregate and molding processability of the prepreg, 1000 Pa · s or less is preferable, 900 Pa · s or less is more preferable, and 800 Pa · s or less is more preferable.

The minimum viscosity of the epoxy resin composition is preferably at least 0.05 Pa · s, more preferably at least 0.07 Pa · s, from the viewpoint of controlling the fluidity of the resin during molding (suppressing disturbance of reinforcing fibers). Is more preferable, and 0.1 Pa · s or more is more preferable. The upper limit of the minimum viscosity is preferably 50 Pa · s or less, more preferably 40 Pa · s or less, and further preferably 30 Pa · s or less.
The minimum viscosity is defined as the point at which the viscosity is lowest in the viscosity curve obtained when the viscosity of the epoxy resin composition is measured in the temperature rising mode.
The viscosity of the epoxy resin composition is determined by measuring, for example, with a rotational viscometer using a 25 mmφ parallel plate, a plate gap of 500 μm, a temperature increase rate of 2 ° C./min, an angular velocity of 10 rad / sec, and a stress of 300 Pa. It is done.

<Pot life of epoxy resin composition>
The epoxy resin composition of the present invention is excellent in pot life. For example, when the glass transition point of the epoxy resin composition immediately after blending and the epoxy resin composition at the time of storage for 90 days in an environment of temperature 20 ° C. and humidity 50% is measured, The rise can be 20 ° C. or less. By increasing the glass transition point to 20 ° C. or less, the reaction of the matrix resin is suppressed even when the epoxy resin composition of the present invention is prepreged and stored at room temperature for a long period of time. This is preferable because the tack and drape remain within an appropriate range and are suitable for handling. More preferably, the increase in the glass transition point is more preferably 15 ° C. or less. The glass transition point can be determined by differential scanning calorimetry (DSC).

<Physical properties of epoxy resin plate>
As for the epoxy resin composition of this invention, it is preferable that the bending strength of the resin hardened | cured material exists in the range of 135-200 MPa. More preferably, it is in the range of 140 to 190 MPa. When the bending strength is less than 135 MPa, the static strength when the fiber-reinforced composite material is obtained may be insufficient. Moreover, when exceeding 200 Mpa, the toughness at the time of setting it as a fiber reinforced composite material tends to become inadequate, and the impact resistance of a fiber reinforced composite material may be insufficient.

  Moreover, the epoxy resin composition of the present invention has an elastic modulus of the cured resin product in the range of 3.3 to 5 GPa, and a breaking elongation of the cured resin product in the range of 8.5 to 15%. preferable. More preferably, the elastic modulus is 3.5 to 5 GPa and the breaking strain is 10 to 14%. When the elastic modulus is less than 3.3 GPa or when the breaking elongation is well over 15%, the static strength in the case of a fiber-reinforced composite material may be insufficient. If it exceeds 5 GPa or if the breaking strain is less than 8.5%, the toughness of the fiber-reinforced composite material tends to be insufficient, and the impact resistance of the fiber-reinforced composite material may be insufficient. Here, about an elastic modulus, it can improve by containing a cellulose nanofiber within the range which does not impair the objective of this invention.

<Effect>
Since the epoxy resin composition of the present invention described above includes the above-described component (A), component (B), component (C) and component (D), and component (E) and other additives as necessary, If the epoxy resin composition of the present invention is used, a fiber-reinforced composite material having excellent mechanical properties can be obtained.

"Molding"
The molded article of the present invention is formed by molding the above-described epoxy resin composition of the present invention.
Examples of the molding method of the epoxy resin composition include an injection molding method (including insert molding of films, glass plates, etc.), an injection compression molding method, an extrusion method, a blow molding method, a vacuum molding method, a pressure molding method, and a calendar molding method. And inflation molding method. Among these, the injection molding method and the injection compression molding method are preferable because they are excellent in mass productivity and can obtain a molded product with high dimensional accuracy.

  Since the molded article of the present invention is formed by molding the epoxy resin composition of the present invention, it is excellent in mechanical properties, and can be applied to, for example, a vehicle product, a casing of a mobile device, a furniture product, a building material product, etc. .

<Film made of epoxy resin composition>
A film of the epoxy resin composition can be obtained by applying the epoxy resin composition of the present invention to a release paper or the like and curing it. This film is useful as an intermediate material for producing a prepreg, and as a surface protective film and an adhesive film by being attached to a substrate and cured.
One aspect of the molded article of the present invention is the use of the aforementioned epoxy resin composition as a film.
Moreover, the usage method is preferable to apply the epoxy resin composition of the present invention to the surface of a substrate such as a release paper. The obtained coating layer may be cured by sticking to another base material without curing, or the coating layer itself may be cured and used as a film.

"Prepreg"
The prepreg of the present invention is obtained by impregnating a reinforcing fiber assembly with the above-described epoxy resin composition of the present invention. Examples of the impregnation method include a wet method in which the epoxy resin composition is dissolved in a solvent such as methyl ethyl ketone and methanol to lower the viscosity and impregnation, and a hot melt method (dry method) in which the viscosity is reduced by heating and impregnation. it can.

  The wet method is a method in which the reinforcing fiber is immersed in a solution of the epoxy resin composition and then lifted and the solvent is evaporated using an oven or the like. The hot melt method directly applies the epoxy resin composition whose viscosity has been reduced by heating. A method of impregnating reinforcing fibers, or a film in which an epoxy resin composition is once coated on release paper or the like is prepared, and then the films are laminated from both sides or one side of the reinforcing fibers and heated and pressed to form reinforcing fibers. This is a method of impregnating a resin. The hot melt method is preferable because substantially no solvent remains in the prepreg.

  The content of the epoxy resin composition relative to the total mass of the prepreg (hereinafter referred to as “resin content”) is preferably 15 to 50% by mass, more preferably 20 to 45% by mass, and even more preferably 25 to 40% by mass. If the resin content is 15% by mass or more, sufficient adhesion between the reinforcing fiber assembly and the epoxy resin composition can be secured, and if it is 50% by mass or less, the mechanical properties can be kept high.

The reinforcing fiber constituting the reinforcing fiber aggregate is not particularly limited, and may be appropriately selected from known ones as the reinforcing fiber constituting the fiber-reinforced composite material, depending on the application, for example, carbon fiber, aramid fiber, nylon Various inorganic fibers or organic fibers such as fibers, high-strength polyester fibers, glass fibers, boron fibers, alumina fibers, and silicon nitride fibers can be used. Among these, carbon fiber, aramid fiber, glass fiber, boron fiber, alumina fiber, and silicon nitride fiber are preferable from the viewpoint of specific strength and specific elasticity, and carbon fiber is particularly preferable from the viewpoint of mechanical properties and weight reduction. The fiber may be surface-treated with a metal.
These may be used individually by 1 type and may be used in combination of 2 or more type.

  As will be described in detail later, when the fiber reinforced plastic obtained by curing the prepreg of the present invention is used for part or all of the rod-like body or structure, the strand tension of the carbon fiber is used from the viewpoint of the rigidity of the fiber reinforced composite material. The strength is preferably 1 to 9 GPa, more preferably 1.5 to 9 GPa, and the strand tensile modulus of carbon fiber is preferably 150 to 1000 GPa, more preferably 200 to 1000 GPa. The strand tensile strength and strand tensile modulus of carbon fiber are measured according to JIS R 7601 (1986).

  The form of the reinforcing fiber aggregate is not particularly limited, and a form used as a base material for a normal prepreg can be adopted. For example, the reinforcing fiber may be aligned in one direction. Or a non-crimp fabric.

  Since the prepreg of the present invention is formed by impregnating the reinforcing fiber assembly with the epoxy resin composition of the present invention, a fiber reinforced plastic having excellent mechanical properties can be obtained by curing.

"Fiber reinforced plastic"
The fiber-reinforced plastic of the present invention is obtained by a method of heat-curing a resin while applying pressure to the laminated body after laminating the above-described prepreg of the present invention.
Since the fiber reinforced plastic is excellent in mechanical properties, flame retardancy, heat resistance, electromagnetic wave shielding properties and the like, it is preferable that the fiber reinforced plastic contains carbon fiber as the reinforcing fiber.

  Examples of methods for applying heat and pressure include a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method, a sheet wrap molding method, and an epoxy resin composition for reinforcing fiber filaments and preforms. Examples include RTM (Resin Transfer Molding), VaRTM (Vacum Assisted Resin Transfer Molding), filament winding, RFI (Resin Film Infusion), etc. It is not limited to the molding method.

The wrapping tape method is a method in which a prepreg is wound around a mandrel or the like and a tubular body made of fiber reinforced plastic is formed, and is a suitable method for producing a rod-like body such as a golf shaft or a fishing rod. More specifically, a prepreg is wound around a mandrel, a wrapping tape made of a thermoplastic film is wound around the outside of the prepreg for fixing and applying pressure, and the resin is heated and cured in an oven, and then a cored bar. This is a method for extracting a fiber and obtaining a fiber-reinforced plastic tubular body.
Also, the internal pressure molding method is to set a preform in which a prepreg is wound on an internal pressure applying body such as a tube made of a thermoplastic resin in a mold, and then introduce a high pressure gas into the internal pressure applying body to apply pressure. At the same time, the mold is heated and molded. This method is preferably used when molding a complicated shape such as a golf shaft, a bat, a racket such as tennis or badminton.

  The fiber reinforced plastic using the cured product of the epoxy resin composition of the present invention as a matrix resin is suitably used for sports applications, general industrial applications, and aerospace applications. More specifically, in sports applications, it is preferably used for golf shafts, fishing rods, tennis and badminton racket applications, stick applications such as hockey, and ski pole applications. Furthermore, in general industrial applications, it is used as a structural material for moving bodies such as automobiles, ships and railway vehicles, drive shafts, leaf springs, windmill blades, pressure vessels, flywheels, paper rollers, roofing materials, cables, and repair and reinforcement materials. Preferably used.

  The tubular body made of fiber-reinforced plastic obtained by curing the prepreg of the present invention into a tubular shape can be suitably used for golf shafts, fishing rods and the like.

"Fiber-reinforced plastic tubular body"
The tubular body made of fiber reinforced plastic can be produced, for example, by the method described in (I) to (V) below.
The unidirectional prepreg is laminated with 2 ply so that the fiber direction is −45 ° and + 45 ° with respect to the cylindrical axis direction, and the unidirectional prepreg is further laminated with 1 ply so that the fiber direction is parallel to the cylindrical axis direction. Are laminated to produce a composite material tubular body having an inner diameter of 6 mm. The mandrel is a stainless steel round bar having a diameter of 6 mm and a length of 300 mm.

(I) Two sheets are cut out from the produced unidirectional prepreg into a rectangular shape having a length of 200 mm and a width of 76 mm (so that the fiber axis direction is 45 degrees with respect to the direction of the long side). The two prepreg fibers are laminated so that the directions of the fibers intersect each other and are shifted by 9 mm in the short side direction.
(II) The mandrel is wound so that the long side of the rectangular shape of the prepreg bonded to the mandrel subjected to the mold release treatment and the mandrel axial direction are in the same direction.
(III) On top of that, a unidirectional prepreg cut into a rectangular shape with a length of 200 mm and a width of 161 mm (the long side direction is the fiber axis direction) so that the fiber direction is the same as the mandrel axis direction. Then, turn around the mandrel.
(IV) Further, a wrapping tape (heat-resistant film tape) is wound on the wound product to cover the wound product, and is heated and molded at 130 ° C. for 90 minutes in a curing furnace. The width of the wrapping tape is 15 mm, the tension is 3 N, the winding pitch (deviation amount at the time of winding) is 1 mm, and this is wrapped so as to have the same thickness as the laminated body.
(V) Thereafter, the mandrel is extracted and the wrapping tape is removed to obtain a fiber-reinforced plastic tubular body.

"Structure"
A structure can be obtained from the fiber-reinforced plastic of the present invention described above. This structure may be composed of only the fiber reinforced plastic of the present invention, or is composed of the fiber reinforced plastic of the present invention and other materials (for example, metal, injection-molded thermoplastic resin member, etc.). It may be done.

Since this structure is partially or entirely made of the fiber reinforced plastic of the present invention, it is excellent in flame retardancy and heat resistance.
This structure can be applied to, for example, an interior member of an aircraft or an automobile, a casing for an electric / electronic device, and the like.

"Interlaminar shear strength of fiber reinforced plastics (ILSS)"
Interlaminar shear strength (ILSS) is a method of measuring interlaminar shear strength of unidirectional fiber-reinforced plastics, which is greatly affected by the interfacial strength between single yarn / matrix resin of reinforcing fibers, by a short test bending test. It is a parameter | index which shows adhesiveness with resin.

  The fiber-reinforced plastic of the present invention can have a very excellent ILSS exceeding 90 MPa, and the ILSS is preferably in the range of 90 to 150 MPa. More preferably, it is 90-140 MPa. When ILSS is less than 90 MPa, the adhesion between the reinforcing fiber and the epoxy resin composition becomes insufficient, and the impact resistance of the fiber-reinforced composite material may be insufficient. If it exceeds 150 MPa, the tensile strength of the fiber-reinforced composite material may be insufficient.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
The raw materials used in the examples and comparative examples are shown below.

"material"
<Component (A)>
AER4152: Oxazolidone skeleton-containing epoxy resin, epoxy equivalent 338 g / eq, “AER4152” manufactured by Asahi Kasei E-Materials Corporation.

<Component (B)>
JER828: Liquid bisphenol A type epoxy resin, epoxy equivalent 189 g / eq, “jER828” manufactured by Mitsubishi Chemical Corporation.
JER807: Liquid bisphenol F type epoxy resin, epoxy equivalent 170 g / eq, “jER807” manufactured by Mitsubishi Chemical Corporation.
JER1002: Solid bisphenol A type epoxy resin, epoxy equivalent 650 g / eq, “jER1002” manufactured by Mitsubishi Chemical Corporation.
JER4007P: Solid bisphenol F type epoxy resin, epoxy equivalent 2270 g / eq, “jER4007P” manufactured by Mitsubishi Chemical Corporation.

<Ingredient (C)>
DICY15: Dicyandiamide, active hydrogen equivalent 21 g / eq, “jER Cure DICY15” manufactured by Mitsubishi Chemical Corporation.
DCMU-99: 3- (3,4-dichlorophenyl) -1,1-dimethylurea, “DCMU-99” manufactured by Hodogaya Chemical Co., Ltd.
Omicure 94: Phenyldimethylurea, “Omicure 94” manufactured by PTI Japan.
2MZA-PW: 2,4-diamino-6- (2′-methylimidazolyl- (1 ′))-ethyl-s-triazine, “Cureazole 2MZA-PW” manufactured by Shikoku Kasei Kogyo Co., Ltd.
Seikacure S: 4,4′-diaminodiphenylsulfone, “Seikacure S” manufactured by Wakayama Seika Kogyo Co., Ltd.

<Masterbatch containing component (B) and component (D)>
YL7883-10: Cellulose nanofiber-containing epoxy resin masterbatch, acetylated cellulose nanofiber (component (D), acetylation degree of about 23.3%) content 10%, liquid bisphenol A type epoxy resin (component (B) ) 90% content, manufactured by Mitsubishi Chemical Corporation.
YL7923-10: Cellulose nanofiber-containing epoxy resin masterbatch, acetylated cellulose nanofiber (component (D), acetylation degree of about 10%) content 10%, liquid bisphenol A type epoxy resin (component (B)) Amount 90%, manufactured by Mitsubishi Chemical Corporation.
YL7951-10: Cellulose nanofiber-containing epoxy resin masterbatch, acetylated cellulose nanofiber (component (D), acetylation degree of about 36.3%) content 10%, liquid bisphenol F type epoxy resin (component (B) ) 90% content, manufactured by Mitsubishi Chemical Corporation.

<Ingredient (E)>
Vinylec E: Polyvinyl formal resin, “Vinylec E” manufactured by JNC Corporation.

<Carbon fiber>
Carbon fiber: “Pyrofil TR50S15L” manufactured by Mitsubishi Rayon Co., Ltd.

"Example 1"
AER4152 as component (A), jER828 and jER1002 as component (B), DICY15 and DCMU-99 as component (C), YL7883-10 as a master batch containing component (B) and component (D), as component (E) Using Vinylec E, an epoxy resin composition was prepared as follows.
First, according to the composition described in Table 1, the component (B) (liquid component of the component (B)) and the component (C) (solid) have a mass ratio of the solid component to the liquid component of 1: 1. Weighed into a container, added a masterbatch containing component (D), stirred and mixed. This was further finely mixed with a three roll mill to obtain a master batch containing a curing agent.
Subsequently, components other than the master batch containing the curing agent in the composition shown in Table 1 were weighed in a flask, heated to 150 ° C. using an oil bath, and dissolved and mixed. After cooling to about 65 ° C., the epoxy resin composition was obtained by adding the hardener-containing master batch and stirring and mixing.
Using the obtained epoxy resin composition, a resin plate was prepared according to <Epoxy resin plate preparation method> described later. Further, the bending characteristics of the resin plate were evaluated according to <Evaluation Method> described later. The resin plate had a bending strength of 164 MPa, a flexural modulus of 3.62 GPa, and a breaking elongation of 12.1%.

"Examples 2 to 10"
The epoxy resin composition was changed in the same manner as in Example 1 except that YL7951-10 was used as a masterbatch containing components (B) and (D) in Examples 5 to 10 except that the composition was changed to the formulation shown in Table 1. Was prepared, a resin plate was prepared, and the measurement and evaluation were performed. The results are shown in Table 1.

  In Table 1, “cellulose nanofiber content (parts by mass)” indicates the cellulose nanofiber content (parts by mass) relative to 100 parts by mass of the total epoxy resin.

"Example 11"
AER4152 as component (A), jER807 and jER4007P as component (B), DICY15 and DCMU-99 as component (C), YL7951-10 as a masterbatch containing component (B) and component (D), as follows Thus, an epoxy resin composition was prepared.
First, according to the composition described in Table 2, the component (B) (liquid component of the component (B)) and the component (C) (solid) have a mass ratio of the solid component to the liquid component of 1: 1. Weighed into a container, added a masterbatch containing component (D), stirred and mixed. This was further finely mixed with a three roll mill to obtain a master batch containing a curing agent.
Subsequently, components other than the master batch containing the curing agent in the composition shown in Table 2 were weighed in a flask, heated to 140 ° C. using an oil bath, and dissolved and mixed. After cooling to about 65 ° C., the epoxy resin composition was obtained by adding the hardener-containing master batch and stirring and mixing.
Using the obtained epoxy resin composition, according to <Epoxy resin plate production method>, <Prepreg production method>, <Fiber reinforced plastic plate production method> and <Fiber reinforced plastic tubular body production method> described later, A prepreg, a fiber reinforced plastic plate, and a fiber reinforced plastic tubular body were produced. Various measurements and evaluations were performed according to <Evaluation method> described later. The resin plate had a bending strength of 176 MPa, a flexural modulus of 4.12 GPa, and a breaking elongation of 13.4%. The ILSS of the fiber reinforced plastic plate was 95.1 MPa. The bending strength of the fiber-reinforced plastic tubular body was 1349 Mpa, and the bending elastic modulus was 53.3 GPa.

"Examples 12 to 14"
It changed to the compounding composition shown in Table 2, and YL78883-10 was used as a masterbatch containing a component (B) and a component (D) in Example 12, and a component (B) and a component (D) were used in Examples 13 and 14. An epoxy resin composition was prepared in the same manner as in Example 11 except that YL7923-10 was used as the master batch to be included, and a resin plate, a prepreg, and a fiber-reinforced plastic plate were produced. Various measurements and evaluations were performed according to <Evaluation method> described later. The results are shown in Table 2.

“Comparative Example 1”
Except having changed into the compounding composition shown in Table 2, after obtaining an epoxy resin composition like Example 11, a resin board, a prepreg, a fiber reinforced plastic board, and a fiber reinforced plastic tubular body were produced, and various measurement And evaluated. The resin plate had a bending strength of 150 MPa, a flexural modulus of 3.24 GPa, and a breaking elongation of 10.4%. The ILSS of the fiber reinforced plastic plate was 84.1 MPa. The bending strength of the fiber reinforced plastic tubular body was 1113 Mpa, and the bending elastic modulus was 50.5 GPa.
The comparative example 1 which does not contain a cellulose nanofiber was inferior in each physical-property value with respect to each Example.

  In Table 2, “cellulose nanofiber content (parts by mass)” indicates the cellulose nanofiber content (parts by mass) relative to 100 parts by mass of the total epoxy resin.

<Epoxy resin plate production method>
The uncured epoxy resin composition was cured at an oven atmosphere temperature of 135 ° C. × 90 minutes (temperature increase rate was 2 ° C./min) to prepare a resin plate having a thickness of 2 mm.

<Prepreg production method>
The uncured epoxy resin composition was formed into a film with a comma coater (“M-500”, manufactured by Hirano Techseed Co., Ltd.), and a resin film having a resin basis weight of 40.4 g / m ² was produced. This resin film is bonded to both surfaces of a carbon fiber sheet having a fiber basis weight of 150 g / m ² obtained by aligning carbon fibers, impregnated with a heating roll, and has a fiber basis weight of 150 g / m ² and a resin content of 35% by mass. Prepreg was obtained.

<Fiber-reinforced plastic plate manufacturing method>
The prepreg obtained in the above <prepreg manufacturing method> is cut into 300 mm × 300 mm, and the fiber direction is [0 ° / 0 ° / 0 ° / 0 ° / 0 ° / 0 ° / 0 ° / 0 ° / 0 ° / [0 ° / 0 ° / 0 ° / 0 ° / 0 °] were stacked to obtain a laminate. The laminate was heated at 2 ° C./min under a pressure of 0.04 MPa in an autoclave, held at 80 ° C. for 60 minutes, then heated at 2 ° C./min under a pressure of 0.6 MPa, and held at 130 ° C. for 90 minutes. And cured by heating to obtain a 2.1 mm thick fiber reinforced plastic plate.

<Fiber-reinforced plastic tubular body manufacturing method>
The tubular body made of fiber reinforced plastic was produced by the method described in (I) to (V) below.
The unidirectional prepreg is laminated with 2 ply so that the fiber direction is −45 ° and + 45 ° with respect to the cylindrical axis direction, and the unidirectional prepreg is further laminated with 1 ply so that the fiber direction is parallel to the cylindrical axis direction. And a fiber-reinforced plastic tubular body having an inner diameter of 6 mm was produced. As the mandrel, a stainless steel round bar having a diameter of 6 mm and a length of 300 mm was used.

(I) Two sheets were cut out from the produced unidirectional prepreg into a rectangular shape of 200 mm in length and 76 mm in width (so that the fiber axis direction was 45 degrees with respect to the direction of the long side). The two prepreg fibers were laminated so that the directions of the fibers crossed each other and shifted by 9 mm in the short side direction.
(II) The mandrel was wound so that the long side of the rectangular shape of the prepreg bonded to the mandrel subjected to the mold release treatment and the mandrel axial direction were the same direction.
(III) On top of that, a unidirectional prepreg cut into a rectangular shape with a length of 200 mm and a width of 161 mm (the long side direction is the fiber axis direction) so that the fiber direction is the same as the mandrel axis direction. I wound up on a mandrel.
(IV) Further, a wrapping tape (heat-resistant film tape) was wrapped around the wound product to cover the wound product, and was heated and molded at 130 ° C. for 90 minutes in a curing furnace. The width of the wrapping tape was 15 mm, the tension was 3 N, the winding pitch (shift amount at the time of winding) was 1 mm, and this was wrapped so as to have the same thickness as the laminate.
(V) Thereafter, the mandrel was extracted, and the wrapping tape was removed to obtain a fiber-reinforced plastic tubular body.

(1) Evaluation of bending characteristics of resin plate The resin plate having a thickness of 2 mm obtained by the above-described <Epoxy resin plate manufacturing method> was processed into a test piece having a length of 60 mm and a width of 8 mm. Using a universal testing machine (manufactured by Instron) equipped with a three-point bending jig (3.2 mmR for both indenter and support, distance between supports: 32 mm), the resin was tested under the condition of a crosshead speed of 2 mm / min. The bending properties (bending strength, flexural modulus, elongation at break (breaking strain)) of the plate were measured.

(2) Interlaminar shear test of fiber reinforced plastic (ILSS)
The fiber-reinforced plastic plate obtained in the above <Fiber-reinforced plastic plate manufacturing method> is formed into a test piece (length 25 mm × width 6.3 mm) so that the reinforcing fibers are oriented at 0 ° with respect to the longitudinal direction of the test piece. The interlaminar shear strength of the fiber reinforced plastic was measured using a universal testing machine (manufactured by INSTRON, product name: INSTRON 4465). In an environment of a temperature of 23 ° C. and a humidity of 50% RH, using a three-point bending jig (indenter R = 3.2 mm, support R = 1.6 mm), the distance between the supports (L) and the thickness of the test piece (d) The interlaminar shear strength (ILSS) of the fiber reinforced composite material was measured as a ratio L / d = 4 and crosshead speed (minute speed) = (L2 × 0.01) / (6 × d).

(3) Evaluation of bending characteristics of fiber-reinforced plastic tubular body A composite material tubular body having an inner diameter of 6 mm and a length of 200 mm prepared by the above-described <Fiber-reinforced plastic tubular body manufacturing method> is a 3-point bending jig (indenter 75 mmR, Using a universal testing machine (Instron) with a support of 12.5 mmR and a distance between supports of 150 mm, the bending properties (bending strength, bending elasticity) of the fiber reinforced plastic tubular body under the condition of a crosshead speed of 20 mm / min Rate).

  By using the epoxy resin composition of the present invention, an excellent tubular fiber-reinforced plastic can be obtained. Therefore, according to the present invention, a wide range of fiber reinforced plastic molded articles having excellent mechanical properties, such as molded articles for sports / leisure use such as golf club shafts, and industrial use such as aircraft can be provided.

Claims (14)

An epoxy resin composition comprising the following components (A), (B), (C) and (D).
Component (A): Oxazolidone skeleton-containing epoxy resin
Component (B): Epoxy resin other than component (A) Component (C): Curing agent Component (D): Cellulose nanofiber   The epoxy resin composition according to claim 1, wherein the component (B) is an epoxy resin having an epoxy equivalent of 350 or more and / or an epoxy resin having an epoxy equivalent of less than 350.   The epoxy resin composition according to claim 1 or 2, wherein the curing agent (C) is at least one selected from dicyandiamide, ureas, imidazoles, and aromatic amines.   The epoxy resin composition as described in any one of Claims 1-3 which contains the said component (A) 5 to 80 mass parts in 100 mass parts of all the epoxy resins.   The epoxy resin composition as described in any one of Claims 1-4 which contains the said component (B) 20 to 95 mass parts in 100 mass parts of all the epoxy resins.   The epoxy resin composition as described in any one of Claims 1-5 which contains the said component (D) 0.1-15 mass parts with respect to 100 mass parts of all the epoxy resins contained in the epoxy resin composition of this invention. object.   The epoxy resin composition according to any one of claims 1 to 6, wherein the cured product has a bending strength of 135 MPa or more, an elastic modulus of 3.3 GPa or more, and a breaking elongation of 8.5% or more.   Furthermore, the epoxy resin composition as described in any one of Claims 1-7 containing a thermoplastic resin as a component (E).   The epoxy resin composition of Claim 8 which contains the said component (E) 1-20 mass parts with respect to 100 mass parts of all the epoxy resins.   The molded article which consists of a hardened | cured material of the epoxy resin composition as described in any one of Claims 1-9.   A prepreg in which a reinforcing fiber is impregnated with the epoxy resin composition according to any one of claims 1 to 9.   A fiber-reinforced plastic comprising a cured product of the epoxy resin composition according to any one of claims 1 to 9 and reinforcing fibers.   The fiber-reinforced plastic according to claim 12, wherein the interlaminar shear strength is 90 MPa or more. The fiber-reinforced plastic according to claim 12 or 13, which is tubular.