JP2018095675A - 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 that makes it possible to obtain a fiber-reinforced composite material having excellent strength and elastic moduli, and provide a molding, a prepreg and a fiber-reinforced plastic prepared with the resin composition.SOLUTION: An epoxy resin composition contains the following components (A), (B), (C) and (D). Component (A) is a bisphenol F type epoxy resin with a softening point of 80°C or more, component (B) is a bisphenol F type epoxy resin with an epoxy equivalent of 250 or less, component (C) is a curing agent, and component (D) is cellulose nanofibers.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. (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 defibrating resin without surface treatment. Known (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, and by using a specific epoxy resin composition containing cellulose nanofibers as a matrix resin, a cured resin having excellent strength, elastic modulus and toughness is formed. The present inventors have found that a fiber-reinforced plastic having excellent mechanical properties can be obtained. The present invention is an epoxy resin composition capable of obtaining a fiber-reinforced composite material having excellent strength and elastic modulus, particularly when applied to a tubular composite material, and a molded article using the resin composition, Provide prepreg and fiber 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): Bisphenol F type epoxy resin having a softening point of 80 ° C. or higher Component (B): Bisphenol F type epoxy resin having an epoxy equivalent of 250 or less Component (C): Curing agent Component (D): Cellulose nanofiber [2] Component The epoxy resin composition according to [1], wherein (C) is at least one selected from dicyandiamide, ureas, imidazoles, and aromatic amines.
[3] The epoxy resin composition according to [1] or [2], wherein the component (A) is contained in an amount of 20 parts by mass or more and 80 parts by mass or less in 100 parts by mass of all epoxy resins.
[4] The epoxy resin composition according to any one of [1] to [3], wherein the component (B) is contained in an amount of 20 parts by mass or more and 80 parts by mass or less in 100 parts by mass of all epoxy resins.
[5] In any one of [1] to [4], 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.
[6] The epoxy resin composition according to any one of [1] to [5], further including a thermoplastic resin as the component (E).
[7] The epoxy resin composition according to [6], including the component (E) in an amount of 1 part by mass to 15 parts by mass with respect to 100 parts by mass of the total epoxy resin.
[8] A molded article comprising a cured product of the epoxy resin composition according to any one of [1] to [7].
[9] A prepreg in which a reinforcing fiber assembly is impregnated with the epoxy resin composition according to any one of [1] to [7].
[10] A fiber-reinforced plastic comprising a cured product of the epoxy resin composition according to any one of [1] to [7] and reinforcing fibers.
[11] The fiber-reinforced plastic according to [10], which is tubular.

  The epoxy resin composition of the present invention gives a cured resin with high strength, high elastic modulus and high toughness, and has excellent mechanical properties by using the epoxy resin composition of the present invention as a matrix resin for fiber reinforced plastics. A fiber reinforced plastic is obtained. In particular, an excellent breaking strength can be obtained by using the epoxy resin composition of the present invention for 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.
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”.
In the present invention, the softening point, epoxy equivalent, and active hydrogen equivalent are values measured under the following conditions.
1) Softening point: A value measured in accordance with JIS-K7234: 2008 (ring and ball method).
2) Epoxy equivalent: A value measured according to JIS K-7236: 2001.
3) Active hydrogen equivalent: A value measured according to JIS K-7237: 1986.

[Epoxy resin composition]
The epoxy resin composition of the present invention (hereinafter also referred to as “the present resin composition”) includes a component (A), a component (B), a component (C), and a component (D). Furthermore, the component (E), other components (F), and additives as optional components may be included.

<Component (A)>
Component (A) is a bisphenol F-type epoxy resin having a softening point of 80 ° C. or higher. If the softening point of a component (A) is 80 degreeC or more, the resin cured material of this resin composition has the outstanding toughness.

More preferably, the resin composition contains the component (A) in an amount of 20 parts by mass or more and 80 parts by mass or less, and 25 parts by mass or more and 75 parts by mass or less, in 100 parts by mass of the total epoxy resin contained in the resin composition. More preferably, it is 30 parts by weight or more and 70 parts by weight or less.
The lower limit of the content of component (A) is preferably 25 parts by mass or more, and more preferably 30 parts by mass or more. Moreover, the upper limit of content of a component (A) becomes like this. Preferably it is 75 mass parts or less, More preferably, it is 70 mass parts or less.
If content of a component (A) is 20 mass parts or more in this resin composition, it exists in the tendency which can obtain the resin cured material excellent in toughness. On the other hand, if the content of the component (A) is 80 parts by mass or less, the heat resistance of the cured resin can be appropriately maintained, a prepreg excellent in tack and drape can be obtained, and fiber reinforcement without voids can be obtained. There is a tendency to obtain a composite material.

A commercial item may be used for a component (A).
The commercially available bisphenol F type epoxy resin (component (A)) having a softening point of 80 ° C. or higher is not limited to these, but jER4004P, jER4005P, jER4007P, jER4010P (all trade names, Mitsubishi Chemical Corporation) And YDF2004 (trade name, manufactured by KUKDO CHEMICAL).
As the component (A), any of the above-described epoxy resins is preferably used in the present invention, and one of these may be used alone, or two or more may be used in combination.

<Component (B)>
Component (B) is a bisphenol F type epoxy resin having an epoxy equivalent of 250 or less. The component (B) mainly contributes to the improvement of the strength, elastic modulus, and heat resistance of the resin cured product of the present resin composition.
This resin composition contains 20 parts by mass or more and 80 parts by mass or less of component (B) in 100 parts by mass of all the epoxy resins contained in the present resin composition.
The minimum of content of a component (B) becomes like this. Preferably it is 25 mass parts or more, More preferably, it is 30 mass parts or more. Moreover, the upper limit of content of a component (B) becomes like this. Preferably it is 75 mass parts or less, More preferably, it is 70 mass parts or less.
If content of a component (B) is 20 mass parts or more in this resin composition, it exists in the tendency which can obtain the resin cured material excellent in intensity | strength and an elasticity modulus. On the other hand, if content of a component (B) is 80 mass parts or less, it exists in the tendency which can obtain the resin cured material excellent in toughness.

A commercial item may be used for a component (B).
Commercially available bisphenol F-type epoxy resins having an epoxy equivalent of 250 or less (component (B)) are not limited to these, but include jER806 (epoxy equivalent 165 g / eq), jER807 (epoxy equivalent 170 g / eq) ( Above, Mitsubishi Chemical Corporation), YDF-170 (epoxy equivalent 170 g / eq) (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), EPICLON 830 (epoxy equivalent 170 g / eq), EPICLON 835 (epoxy equivalent 172 g / eq) (above, DIC stock) Company), D.M. E. R354 (epoxy equivalent 170 g / eq) (made by THE DOW CHEMICAL COMPANY) etc. are mentioned. One of these may be used alone, or two or more may be used in combination.

<Ingredient (C)>
Component (C) is a curing agent. Although it does not specifically limit as a hardening | curing agent used as a component (C), For example, a dicyandiamide, ureas, imidazoles, aromatic amines, other amine type hardening | curing agents, an acid anhydride, a boron chloride amine complex, etc. are mentioned.
Component (C) may be used in combination of two or more of them, and may be used alone, but is selected from dicyandiamide, ureas, imidazoles and aromatic amines. It is preferable that there is at least one.

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

The content of dicyandiamide in the resin composition is such that the number of active hydrogen moles (active hydrogen equivalent) of dicyandiamide is 0.4 to 1 with respect to the total number of epoxy groups of the epoxy resin contained in the resin composition. An amount of 0.0 times is preferable.
If the number of moles is 0.4 times or more, it is preferable because a cured resin product having good heat resistance and good mechanical properties, that is, high strength and elastic modulus can be obtained. Further, it is preferable that the number of moles is 1.0 times or less because a cured resin product having good mechanical properties, that is, excellent plastic deformation ability and impact resistance can be obtained.
It is more preferable that the number of moles of active hydrogen of dicyandiamide is 0.5 to 0.8 times because a cured resin product having more excellent heat resistance is obtained.
As dicyandiamide, a commercially available product may be used.
Examples of commercial products of dicyandiamide include DICY7, DICY15 (active hydrogen equivalent 21 g / eq) (manufactured by Mitsubishi Chemical Corporation), DICYANEX 1400F (active hydrogen equivalent 21 g / eq) (manufactured by Air Products), and the like. It is not limited to.

The ureas used as the component (C) have a dimethylureido group in the molecule, and when heated at a high temperature, form an isocyanate group and dimethylamine, and these products are the component (A) and the component (B). The epoxy group and other components (C) to be used in combination are not particularly limited.
Examples of such ureas include aromatic dimethylurea in which a dimethylureido group is bonded to an aromatic ring, and aliphatic dimethylurea in which a dimethylureido group is bonded to an aliphatic compound. Among these, aromatic dimethylurea is preferred because the curing rate is increased and the heat resistance and bending strength of the cured product tend to increase.

  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. If the urea content is 1 part by mass or more, the epoxy resin contained in the epoxy resin composition can be sufficiently cured and cured, and the mechanical properties and heat resistance can be increased. On the other hand, if the urea content is 15 parts by mass or less, it is preferable because the toughness of the cured resin can be kept 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, but are not limited thereto.
Among these, DCMU, MBPDMU, TBDMU, and PDMU are more preferable in terms of curing acceleration ability and imparting heat resistance to the cured resin.
These may be used alone or in combination of two or more.
Examples of the aliphatic dimethylurea include, but are not limited to, dimethylurea obtained from isophorone diisocyanate and dimethylamine, dimethylurea obtained from hexamethylene diisocyanate and dimethylamine, and the like.

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

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 its structure, which activates the epoxy group of component (A) or component (B), and also activates component (C) to be used in combination. And can promote curing and curing.

  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 the content of imidazoles is 1 part by mass or more, the epoxy resin contained in the epoxy resin composition tends to be sufficiently cured and cured, and heat resistance tends to be obtained. On the other hand, if the content of imidazoles is 15 parts by mass or less, it is preferable because a cured resin having excellent mechanical properties tends to be obtained.

  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.

  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 can obtain a cured product having a small coefficient of linear expansion and a decrease in heat resistance due to moisture absorption. . 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 in combination of two or more as appropriate.

  The compounding amount of aromatic amines, particularly for diaminodiphenyl sulfone, the number of active hydrogen equivalents of amino groups is 0.5 to 1.5 of 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. If the blending amount of these epoxy resin curing agents is 0.5 to 1.5 times, the elastic modulus, toughness and heat resistance of the cured epoxy resin tend to be in a favorable range.

Moreover, a commercial item may be used for aromatic amines.
Commercially available products of 4,4′-diaminodiphenylsulfone include Seika Cure S (active hydrogen equivalent 62 g / eq, manufactured by Wakayama Seika Kogyo Co., Ltd.), Sumicure S (active hydrogen equivalent 62 g / eq, manufactured by Sumitomo Chemical Co., Ltd.) As a commercial product of 3,3′-diaminodiphenylsulfone, 3,3′-DAS (active hydrogen equivalent 62 g / eq, manufactured by Mitsui Chemicals Fine Co., Ltd.) and the like can be mentioned, but are not limited thereto.
Other commercially available aromatic amines include MDA-220 (active hydrogen equivalent 50 g / eq, manufactured by Mitsui Chemicals), “jER Cure (registered trademark)” W (active hydrogen equivalent 45 g / eq, Japan Epoxy). Resin Co., Ltd.), Lonacure (registered trademark) M-DEA (active hydrogen equivalent 78 g / eq), “Lonzacure (registered trademark)” M-DIPA (active hydrogen equivalent 92 g / eq), “Lonacure (registered trademark)” Examples include, but are not limited to, M-MIPA (active hydrogen equivalent: 78 g / eq) and “Lonzacure (registered trademark)” DETDA 80 (active hydrogen equivalent: 45 g / eq) (hereinafter, manufactured by Lonza).

Other amine curing agents that can be used as component (C) include, but are not limited to, metaphenylenediamine, diaminodiphenylmethane, metaxylenediamine, isophoronediamine, triethylenetetramine, and the like.
Examples of the acid anhydride that can be used as the component (C) include, but are not limited to, hydrogenated methyl nadic acid anhydride and methyl hexahydrophthalic acid anhydride.

<Component (D)>
Component (D) is cellulose nanofiber.
Cellulose nanofibers used in the resin composition as the component (D) are obtained by defibrating and / or refining various celluloses, and by blending in the resin composition, the breaking strength of the cured resin can be increased. Can be improved.

The epoxy resin composition of this invention contains 0.1-15 mass parts of component (D) with respect to 100 mass parts of all the epoxy resins contained in this resin composition. The lower limit of the content of component (D) is more preferably 0.3 parts by mass or more, and further preferably 0.5 parts by mass or more. On the other hand, the upper limit of the content of component (D) is more preferably 13 parts by mass or less, and still more preferably 10 parts by mass or less.
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, and is preferable. 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 non-hardening of an epoxy resin composition to become an appropriate range, it is preferable.

  The cellulose used in the present invention is not limited as long as it can be used as a defibrating material and / or a refining material. Regenerated cellulose fibers such as pulp, cotton, paper, rayon, cupra, polynosic acetate, bacteria-producing cellulose, sea squirt Animal-derived cellulose such as can be used. These celluloses may be subjected to chemical modification treatment on 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.

The cellulose nanofiber that can be used in the present invention may be subjected to a chemical modification treatment in order to enhance functionality. That is, the cellulose nanofiber may be a modified cellulose nanofiber.
The modified cellulose nanofibers can be obtained by defibrillating and / or refining cellulose to produce cellulose nanofibers, and further adding a modifying compound and reacting with the cellulose nanofibers. That is, the modified cellulose nanofiber is obtained by a reaction in which the hydroxyl group on the surface of the cellulose nanofiber is chemically modified with a modifying group and the hydroxyl group is reduced.
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 in such a manner that the compound to be modified is physically adsorbed on the cellulose nanofibers without forming a chemical bond by a chemical reaction. 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 diameter of 2 to 1,000 nm determined by observation with an electron microscope. The average fiber diameter of cellulose nanofibers is more preferably 2 to 700 nm, and further preferably 2 to 500 nm. If the average fiber diameter of the cellulose nanofiber exceeds the upper limit, it becomes difficult to obtain the high strength and rigidity, the high dimensional stability, and the high dispersibility when combined with the resin, which are the characteristics of the cellulose nanofiber. Become. If the average fiber diameter of the cellulose nanofibers is less than the lower limit, it will dissolve in the dispersion medium as cellulose molecules, making it difficult to obtain the high strength, high rigidity, and high dimensional stability that are the characteristics of cellulose nanofibers. become.

  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 the average fiber length is equal to or more than the lower limit, it is preferable because the effect of improving the strength when cellulose nanofibers are blended with the resin tends to be sufficiently obtained. If average fiber length is below the said upper limit, since it exists in the tendency for the mixability at the time of mix | blending a cellulose nanofiber to resin, it is preferable. The average fiber length can be determined, for example, by analyzing an electron microscope observation image used when measuring the average fiber diameter.

It is preferable that cellulose nanofiber can be used for this resin composition as a masterbatch disperse | distributed to matrix resins, such as an epoxy resin.
As a master batch in which cellulose nanofibers are dispersed in a bisphenol F type epoxy resin having an epoxy equivalent of 250 or less, there is YL7951-10 (manufactured by Mitsubishi Chemical Corporation), but is not limited thereto. Moreover, YL7883-3, YL7883-5, YL7883-10, YL7883-15, YL7923-3, YL7923-5, YL7923- as a master batch in which cellulose nanofibers are dispersed in a bisphenol A type epoxy resin having an epoxy equivalent of 250 or less. 10, YL7923-15 (above, manufactured by Mitsubishi Chemical Corporation), etc., but is not limited thereto.

When using the said masterbatch for this resin composition, you may consider content of a component (D) as the total mass of the cellulose nanofiber disperse | distributed to the epoxy resin in a masterbatch, or a modified cellulose nanofiber.
Moreover, when using the masterbatch which disperse | distributed component (D) to the bisphenol F-type epoxy resin of epoxy equivalent 250 or less, the mass of the bisphenol F-type epoxy resin contained in this masterbatch is used for the component (B). Add up with content.
On the other hand, when a masterbatch in which component (D) is dispersed in a bisphenol A type epoxy resin having an epoxy equivalent of 250 or less is used, the mass of the bisphenol A type epoxy resin contained in the masterbatch is changed to a component (F ) Content. However, if the resin composition does not contain the component (F) except for the component derived from the master batch, the content of the component (F) is the mass of the bisphenol A type epoxy resin contained in the master batch. May be considered the same.

<Ingredient (E)>
The thermoplastic resin is blended as necessary in the epoxy resin composition of the present invention as a component (E) for the purpose of controlling the resin flow during molding of the epoxy resin composition of the present invention and imparting toughness to the cured resin. be able to. That is, the resin composition preferably further contains a thermoplastic resin as the component (E).

This resin composition preferably contains 1 part by mass or more and 15 parts by mass or less, preferably 2 parts by mass or more and 10 parts by mass or less, of component (E) with respect to 100 parts by mass of the total epoxy resin contained in the resin composition. It is more preferable.
If content of a component (E) is 1 mass part or more, since it exists in the tendency for the resin flow control and a physical-property improvement effect to be exhibited favorably, it is preferable. On the other hand, if the content of the component (E) is 15 parts by mass or less, the viscosity of the epoxy resin composition, the heat resistance and mechanical properties of the cured resin, and the prepreg tack and drape tend to be easily maintained well. This is preferable.

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 include, but are not limited to, 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. Further, the phenoxy resin is preferable from the viewpoint of further increasing the flame retardancy of the resin cured product, and the polyvinyl formal resin can easily control the tack of the obtained prepreg within an appropriate range without impairing the heat resistance of the cured product. Moreover, it is preferable from a viewpoint of improving the adhesiveness of a reinforced fiber and an epoxy resin composition. A block polymer is preferable because it improves toughness and impact resistance.
These thermoplastic resins 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.).
As polyvinyl formal resin, vinylec (registered trademark) K (average molecular weight: 59,000), vinylec L (average molecular weight: 66,000), vinylec H (average molecular weight: 73,000), vinylec E (average molecular weight: 126) , 000) (manufactured by JNC Corporation) and the like.

  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: 16,400), SUMIKAEXCEL 5003P (average molecular weight: 30,000), SUMIKAEXCEL 5200P (average molecular weight: 35,000), SUMIKAEXCEL 7600P (average molecular weight: 45,300) (above, manufactured by Sumitomo Chemical Co., Ltd.) and the like. Examples of the polyetherimide include ULTEM 1000 (average molecular weight: 32,000), ULTEM 1010 (average molecular weight: 32,000), ULTEM 1040 (average molecular weight: 20,000) (above, manufactured by GE Plastics Co., Ltd.) and the like. However, it is not limited to these.

  As block polymers, Nanostrength M52, Nanostrength M52N, Nanostrength M22, Nanostrength M22N, Nanostrength 123, Nanostrength 250, Nanostrength 012, Nanostrength 012, Nanostrength 012 , TPAE-23, TPAE-31, TPAE-38, TPAE-63, TPAE-100, PA-260 (manufactured by T & K TOKA), and the like, but are not limited thereto.

As the other component (F), the present resin composition improves the workability by adjusting the viscoelasticity of the resin composition when not cured, and improves the strength, elastic modulus, toughness, and heat resistance of the cured resin. For the purpose, the epoxy resin described below may be included.
Although it does not restrict | limit especially as a component (F), A bifunctional or more epoxy resin is used preferably. For example, bisphenol A type epoxy resin, bisphenol S type epoxy resin, oxazolidone type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, trisphenol Glycidylamine type epoxy resins such as methane type epoxy resin, tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol; glycidyl ether type epoxy resins other than the above such as tetrakis (glycidyloxyphenyl) ethane, tris (glycidyloxy) methane, and Examples thereof include epoxy resins modified with these, phenol aralkyl type epoxy resins, and the like.
As the bifunctional epoxy resin, a bisphenol A type epoxy resin is particularly preferably used from the viewpoint of the viscosity and heat resistance 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 novolac-type epoxies A resin and a cresol novolac type epoxy resin are preferably used.

  Examples of commercially available epoxy resins used as the component (F) include jER828 (epoxy equivalent 189 g / eq), jER1001 (epoxy equivalent 475 g / eq), jER1002 (epoxy equivalent 650 g / eq), jER1004 (epoxy equivalent 925 g / eq). 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 (epoxy 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, Ryo Chemical Co., Ltd.); 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) (above, Japan) YDPN-638 (epoxy equivalent 180 g / eq), TX-0911 (epoxy equivalent 172 g / eq) (above, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), Epon 165 (epoxy equivalent 230 g / eq) (above, 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), P-4700 (epoxy equivalent 162 g / eq), HP-7200 (epoxy equivalent 265 g / eq), TSR-400 (above, manufactured by DIC Corporation); AER4152, AER4151, LSA3301, LSA2102 (above, Asahi Kasei E-Materials Corporation) ), ACR1348 (epoxy equivalent 350 g / eq) (above, manufactured by ADEKA Corporation); DER852 (epoxy equivalent 320 g / eq), DER858 (epoxy equivalent 400 g / eq) (above, manufactured by DOW) and the like. However, it is not limited to these.

  As for content of a component (F), 5-35 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 10-30 mass parts is more preferable. If content of a component (F) is 5 mass parts or more, since there exists a tendency for the physical-property improvement effect to be exhibited favorable, it is preferable. On the other hand, if the content of the component (F) is 35 parts by mass or less, the properties of the epoxy resin composition of the present invention tend to be favorably maintained, which is preferable.

<Optional component>
The resin composition 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 alone or in combination of two or more.

<Viscosity of epoxy resin composition>
The viscosity of the resin composition at 30 ° C. is preferably 100 Pa · s or more, more preferably 300 Pa · s or more, and 500 Pa · s or more, from the viewpoint of adjusting the tack of the obtained prepreg surface and workability. Is more preferable. The upper limit of the viscosity is preferably 1,000,000 Pa · s or less, more preferably 900,000 Pa · s or less, and further preferably 800,000 Pa · s or less.
The viscosity of the 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, 1,000 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 present resin composition is preferably 0.05 Pa · s, and the lower limit of the minimum viscosity is 0.05 Pa · s, from the viewpoint of flow control of the resin during molding (suppression of disturbance of reinforcing fibers). s is more preferable, and 0.1 Pa · s is even more preferable. The upper limit of the minimum viscosity is preferably 50 Pa · s, more preferably 40 Pa · s, and further preferably 30 Pa · s.
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, for example, a rotational gap meter (TA Instruments, product name “AR-G2”) using a 25 mmφ parallel plate, a plate gap of 500 μm, and a heating rate of 2 ° C./min. It is obtained by measuring at a temperature rise, an angular velocity of 10 rad / sec, and a stress of 300 Pa.

<Pot life of epoxy resin composition>
This resin composition 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 glass transition point after 90 days has elapsed. The increase in the temperature 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>
In the epoxy resin composition of the present invention, the elastic modulus of the cured resin is preferably in the range of 3.5 to 5 GPa, and the elongation at break of the cured resin is in the range of 10 to 15%. Is preferred. More preferably, the elastic modulus is 3.6 to 5.0 GPa and the breaking strain is 10 to 14%. When the elastic modulus is less than 3.5 GPa or when the elongation at break exceeds 15%, the static strength in the case of a fiber-reinforced composite material may be insufficient. When it exceeds 5 GPa or when the breaking strain is less than 10%, 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 effect of this invention.

<Method for producing epoxy resin composition and use>
Although the epoxy resin composition of this invention is not limited to this, For example, it is obtained by mixing each component mentioned above.
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.
The resin composition can be used, for example, in the production of a prepreg by impregnating a reinforcing fiber assembly as described later. In addition, a film of the resin composition can be obtained by applying the resin composition to a release paper or the like and curing it.

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

〔Molding〕
The molded article of the present invention comprises a cured product of 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, but are not limited thereto.
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>
One embodiment of the molded article of the present invention is the use as a film. This film is useful as an intermediate material for producing a prepreg, and also as a surface protective film or an adhesive film by being cured after being attached to a substrate.
Moreover, although the usage method is not limited to this, it is preferable to apply | coat the epoxy resin composition of this invention to the surface of base materials, such as a release paper. The obtained coating layer may be used as a film by being stuck to another substrate while being uncured and cured, or may be used as a film by curing the coating layer itself.

[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. The method of impregnating the reinforcing fiber assembly with the resin composition may be a known method, for example, a wet method in which the resin composition is dissolved in a solvent such as methyl ethyl ketone or methanol to reduce the viscosity and then impregnated. Examples thereof include, but are not limited to, a hot melt method (dry method) that is impregnated after the viscosity is reduced by heating.

The wet method is a method in which a reinforcing fiber is immersed in a solution of an epoxy resin composition, then pulled up, and the solvent is evaporated using an oven or the like. On the other hand, in the hot melt method, a method of directly impregnating reinforcing fibers with an epoxy resin composition whose viscosity has been reduced by heating, and a film in which the epoxy resin composition is once coated on release paper or the like are prepared, There is a method in which the reinforcing fiber is impregnated with resin by overlapping the film from both sides or one side of the reinforcing fiber and heating and pressing.
The hot melt method is preferable because there is substantially no solvent remaining in the prepreg.

  The content of the epoxy resin composition of the prepreg of the present invention (hereinafter referred to as “resin content”) is preferably 15 to 50% by mass, where the total mass of the prepreg of the present invention is 100%. More preferably, it is -45 mass%, and it is further more preferable that it is 25-40 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 assembly is not particularly limited, and may be appropriately selected from known reinforcing fibers constituting the fiber-reinforced composite material according to the use. Specific examples include various inorganic fibers or organic fibers such as carbon fiber, aramid fiber, nylon fiber, high-strength polyester fiber, glass fiber, boron fiber, alumina fiber, and silicon nitride fiber. 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. When carbon fiber is used as the reinforcing fiber, surface treatment with metal may be performed.
These reinforcing fibers may be used alone or in combination of two or more.

From the viewpoint of the rigidity of the fiber-reinforced composite material obtained by curing the prepreg of the present invention, the strand tensile strength of the carbon fiber is preferably 1 to 9 GPa, more preferably 1.5 to 9 GPa, and the strand tensile elastic modulus of the carbon fiber. Is preferably 150 to 1,000 GPa, more preferably 200 to 1,000 GPa.
The strand tensile strength and strand tensile elastic modulus of the carbon fiber are values measured in accordance with 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, it can be used as a raw material for fiber reinforced plastic having excellent mechanical properties.

[Fiber reinforced plastic]
The fiber reinforced plastic of the present invention is composed of a cured product of the above-described epoxy resin composition of the present invention and a reinforced fiber.
The fiber reinforced plastic of the present invention is not limited to this, and is obtained, for example, by laminating the above-described prepreg of the present invention and then molding it by a method of heat curing an epoxy resin while applying pressure to the laminate. .
Since the fiber reinforced plastic of the present invention is excellent in mechanical properties, flame retardancy, heat resistance, electromagnetic wave shielding properties, and the like, it is preferable that carbon fibers are included as reinforcing fibers.

  The fiber reinforced plastic molding method of the present invention includes 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 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 preferably used when 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 suitably used for golf shafts, fishing rods, tennis and badminton racket applications, hockey stick applications, and ski pole applications. Furthermore, in general industrial applications, structural materials 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 reinforcement materials, etc. Is preferably used.

<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 (ILSS) of fiber reinforced plastic>
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.
ILSS is a value measured under conditions of a temperature of 23 ° C. and a humidity of 50% RH using a universal testing machine (“INSTRON 5565” manufactured by INSTRON).

The fiber reinforced plastic of the present invention has a very good ILSS, the value of which exceeds 90 MPa. ILSS is preferably in the range of 90 to 150 MPa, and more preferably in the range of 90 to 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. When ILSS exceeds 150 MPa, the tensile strength of the fiber-reinforced composite material may be insufficient.

[Fiber-reinforced plastic tubular body]
The fiber-reinforced plastic tubular body is the fiber-reinforced plastic of the present invention which is tubular. That is, it is a tubular fiber reinforced plastic obtained by laminating, curing and molding the above-described prepreg of the present invention by a known molding method such as a wrapping tape method.
Since the fiber-reinforced plastic tubular body of the present invention has excellent breaking strength and elastic modulus, it can be suitably used for golf shafts, fishing rods and the like.

The tubular body made of fiber reinforced plastic can be obtained from a unidirectional prepreg obtained by impregnating a reinforcing fiber aligned in one direction with the resin composition of the present invention. 2 ply of the prepreg is laminated so that the fiber direction of the unidirectional prepreg is −45 ° and + 45 ° with respect to the cylindrical axis direction, and the unidirectional prepreg is further made parallel to the cylindrical axis direction. Further, 1 ply of prepreg can be laminated to produce a composite material tubular body having an inner diameter of 6 mm. Here, the mandrel is a round bar made of stainless steel.
Specifically, for example, it can be produced by the method described in the following (I) to (V), but is not limited thereto.
(I) From the produced unidirectional prepreg, two rectangular prepregs having a length of 200 mm and a width of 76 mm are cut out so that the fiber axis direction is 45 degrees with respect to the long side direction. 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 bonded prepreg is wound on the mandrel subjected to the mold release treatment so that the long side and the mandrel axial direction are the same direction.
(III) On top of that, a rectangular prepreg 200 mm long × 161 mm wide cut from the produced unidirectional prepreg so that the long side direction is the fiber direction, the fiber direction is the same as the mandrel axis direction. Turn around the mandrel so that
(IV) Further, a heat-resistant film tape is wrapped as a wrapping tape 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.

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.
The softening point and epoxy equivalent were measured under the following conditions.
1) Softening point: Measured according to JIS-K7234: 2008 (ring and ball method).
2) Epoxy equivalent: Measured according to JIS-K7236: 2001.
3) Active hydrogen equivalent: Measured according to JIS-K7237: 1986.

"material"
<Component (A)>
jER4004P: Solid bisphenol F type epoxy resin (softening point 85 ° C., manufactured by Mitsubishi Chemical Corporation, product name “jER4004P”).
jER4007P: Solid bisphenol F type epoxy resin (softening point 108 ° C., manufactured by Mitsubishi Chemical Corporation, product name “jER4007P”).
<Component (B)>
jER807: Liquid bisphenol F type epoxy resin (epoxy equivalent 170 g / eq, manufactured by Mitsubishi Chemical Corporation, product name “jER807”).
<Ingredient (C)>
DICY15: Dicyandiamide (active hydrogen equivalent 21 g / eq, manufactured by Mitsubishi Chemical Corporation, product name “jER cure DICY15”).
DCMU-99: 3- (3,4-dichlorophenyl) -1,1-dimethylurea (manufactured by Hodogaya Chemical Co., Ltd., product name “DCMU-99”).
Omicure 94: N, N-dimethyl-N′-phenylurea (manufactured by PTI Japan, product name “Omicure 94”).
<Masterbatch containing component (D)>
The product name “YL7951-10” manufactured by Mitsubishi Chemical Corporation was used as the master batch containing the component (D). YL7951-10 is composed of acetylated cellulose nanofibers (component (D)) having an acetylation degree of about 36% and liquid bisphenol F type epoxy resin (component (B)). As shown in Table 1, the composition was adjusted to include 9 parts by mass of component (B) and 1 part by mass of component (D) with respect to 100 parts by mass of the total epoxy resin.
About the mass of the bisphenol F type epoxy resin contained in a masterbatch, it adds together with content of a component (B), About the mass of the cellulose nanofiber derived from a masterbatch, content of the component (D) in this composition It was.
That is, “jER807 (component (B)) [part]” in “Masterbatch [part] containing component (D)” in Table 1 is derived from the masterbatch with respect to 100 parts by mass of the total epoxy resin of the resin composition. The content (parts by mass) of the component (B) is shown, and “acetylated cellulose nanofibers (component (D)) [parts]” are cellulose nanofibers (components) with respect to 100 parts by mass of the total epoxy resin of the resin composition. (D)) content (parts by mass) is shown.
<Ingredient (E)>
Vinylec K: Polyvinyl formal resin (manufactured by JNC Corporation, product name “Vinyleck K”).
<Component (F)>
MY-0600: m-aminophenol type epoxy resin (epoxy equivalent 105 g / eq, manufactured by Huntsman Japan KK, product name “MY-0600”).
jER828: Liquid bisphenol A type epoxy resin (epoxy equivalent 189 g / eq, manufactured by Mitsubishi Chemical Corporation, product name “jER828”).
jER1004: Solid bisphenol A type epoxy resin (softening point 97 ° C., manufactured by Mitsubishi Chemical Corporation, product name “jER1004”).
<Carbon fiber>
Carbon fiber: Mitsubishi Rayon Co., Ltd., product name “Pyrofil TR50S15L”.

Example 1
JER4004P is used as component (A), jER807 is used as component (B), DICY15 and DCMU-99 are used as component (C), YL7951-10 is used as a masterbatch containing component (D), and an epoxy resin composition is prepared as follows. Prepared.
First, according to the composition described in Table 1, the solid component (C) was weighed in a container. Next, the component (B) was weighed in the container so that the mass ratio of the liquid component (B) to the solid component (C) was 1: 1. Next, according to the composition described in Table 1, a master batch containing the component (D) was added to the vessel and stirred, and these were mixed. The obtained mixture was further finely mixed with a three-roll mill to obtain a master batch containing a curing agent.
Subsequently, the total amount of the component (A) in the components listed in Table 1 and the remaining amount of the component (B) excluding the amount used in the master batch containing the curing agent were weighed in a flask and 140 using an oil bath. The mixture was dissolved and mixed by heating to ° C. Then, when it cooled to about 65 degreeC, the uncured epoxy resin composition was obtained by adding the said masterbatch containing a hardening | curing agent to a flask and stirring and mixing.

"Production of epoxy resin board"
An uncured epoxy resin composition is poured between two glass plates, molded into a plate shape, heated at 2 ° C./min, held at an oven atmosphere temperature of 135 ° C. for 90 minutes, and cured by heating. A resin plate having a thickness of 2 mm was produced.
"Preparation of prepreg"
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. An uncured prepreg was obtained.
"Production of fiber-reinforced plastic plate"
The uncured prepreg having a resin content of 35% by mass obtained above was cut into 300 mm × 300 mm, and the fiber direction was [0 ° / 0 ° / 0 ° / 0 ° / 0 ° / 0 ° / 0 ° / 0. 14 layers were stacked to obtain a laminated body so as to be [° / 0 ° / 0 ° / 0 ° / 0 ° / 0 ° / 0 °]. 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.
"Production of fiber-reinforced plastic tubular body"
The tubular body made of fiber reinforced plastic was produced by the method described in (I) to (VI) below.
(I) From the unidirectional prepreg having a resin content of 35% by mass produced as described above, two rectangular prepregs having a length of 200 mm and a width of 76 mm are arranged so that the fiber axis direction is 45 degrees with respect to the long side direction. Cut out. 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 prepreg bonded to the mandrel subjected to the mold release treatment was wound so that the long side and the mandrel axial direction were the same direction. As the mandrel, a stainless steel round bar having a diameter of 6 mm and a length of 300 mm was used.
(III) On top of that, a rectangular prepreg 200 mm long × 161 mm wide cut from the produced unidirectional prepreg so that the long side direction is the fiber direction, the fiber direction is the same as the mandrel axis direction. I wound up on a mandrel.
(IV) Further, a heat-resistant film tape was wrapped as a wrapping tape from the top 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 pulled out and the wrapping tape was removed to obtain a fiber-reinforced plastic tubular body having an inner diameter of 6 mm and a length of 200 mm.

  About the produced epoxy resin board, prepreg, and fiber reinforced plastic, various measurements and evaluation were performed according to description of each following evaluation method. The results are shown in Table 1.

“Measurement of bending strength, flexural modulus, elongation at break (breaking strain) of epoxy resin plate”
The resin plate having a thickness of 2 mm obtained in “Preparation of epoxy resin plate” was processed into a length of 60 mm × width of 8 mm to obtain a test piece. The test piece was universally equipped with a three-point bending jig (indenter R = 3.2 mm, support R = 3.2 mm, distance between supports (L) = 32 mm) in an environment of a temperature of 23 ° C. and a humidity of 50% RH. Using a testing machine (“INSTRON 5565” manufactured by INSTRON), the bending strength, bending elastic modulus, and breaking elongation (breaking strain) of the epoxy resin plate were measured under conditions of a crosshead speed of 2 mm / min.

“Measurement of 90 ° flexural modulus of fiber reinforced plastic sheet”
The 2.1 mm thick fiber reinforced plastic plate obtained in the above-mentioned “Preparation of Fiber Reinforced Plastic Plate” was processed into a test piece by length 60 mm × width 12.7 mm. About this test piece, using a universal testing machine (“INSTRON 5565” manufactured by INSTRON) equipped with a three-point bending jig (indenter R = 5.0 mm, support R = 3.2 mm), the distance between supports (L ) And test piece thickness (d) ratio L / d = 16, crosshead speed (minute speed) = (L ² × 0.01) / (6 × d), and 90 as bending characteristics of the fiber reinforced plastic plate ° Flexural modulus was measured.

"Measurement of interlaminar shear strength (ILSS) of fiber reinforced plastic sheet"
The fiber-reinforced plastic plate obtained in the above-mentioned “Preparation of fiber-reinforced plastic plate” 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 ("INSTRON 445565" manufactured by INSTRON). 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) = (L ² × 0.01) / (6 × d).

"Measurement of bending strength and flexural modulus of fiber reinforced plastic tubular body"
A three-point bending jig (indenter R = 75 mm, support R = 12.5 mm, distance between supports) obtained from the above-mentioned “production of a fiber-reinforced plastic tubular body” is a fiber-reinforced plastic tubular body having an inner diameter of 6 mm and a length of 200 mm. (L) = 150 mm) using a universal testing machine ("INSTRON 5565", manufactured by INSTRON), with a crosshead speed of 20 mm / min. The elastic modulus was measured.

<< Examples 2 to 9, Comparative Examples 1 to 3 >>
An epoxy resin composition was prepared in the same manner as in Example 1 except that the composition ratio was changed as in the composition shown in Table 1, and a resin plate, a prepreg, a fiber reinforced plastic plate, a fiber reinforced plastic tubular body was prepared. Were prepared and subjected to various measurements and evaluations. The evaluation results are shown in Table 1.

  As shown in Table 1, each Example was excellent in the bending strength and bending elastic modulus of the epoxy resin plate, while maintaining the same toughness as Comparative Example 1 not containing the cellulose nanofiber of component (D). Moreover, as can be seen from a comparison between Example 3 and Example 4, the bending strength of the epoxy resin plate, the fiber reinforced plastic plate and the fiber reinforced plastic tubular body was improved as the content of the cellulose nanofiber was increased.

  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 (11)

An epoxy resin composition comprising the following components (A), (B), (C) and (D).
Component (A): Bisphenol F type epoxy resin having a softening point of 80 ° C. or higher Component (B): Bisphenol F type epoxy resin having an epoxy equivalent of 250 or less Component (C): Curing agent Component (D): Cellulose nanofiber   The epoxy resin composition according to claim 1, wherein component (C) is at least one selected from dicyandiamide, ureas, imidazoles, and aromatic amines.   The epoxy resin composition of Claim 1 or 2 which contains the said component (A) 20 to 80 mass parts in 100 mass parts of all epoxy resins.   The epoxy resin composition as described in any one of Claims 1-3 which contains the said component (B) 20 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 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 for the said component (D). object.   Furthermore, the epoxy resin composition as described in any one of Claims 1-5 containing a thermoplastic resin as a component (E).   The epoxy resin composition of Claim 6 which contains the said component (E) 1-15 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 1-7.   A prepreg obtained by impregnating a reinforcing fiber assembly with the epoxy resin composition according to any one of claims 1 to 7.   A fiber reinforced plastic comprising a cured product of the epoxy resin composition according to any one of claims 1 to 7 and a reinforcing fiber.   The fiber-reinforced plastic according to claim 10, which is tubular.