JP2023115099A - Epoxy resin film and fiber-reinforced epoxy resin composite material - Google Patents

Abstract

To provide: a fiber-reinforced epoxy resin composite material which can afford a fiber-reinforced plastic having extremely scarce voids and excellent mechanical properties; and the fiber-reinforced plastic using the fiber-reinforced epoxy resin composite material.SOLUTION: Provided is a fiber-reinforced epoxy resin composite material formed by impregnating reinforcing fibers with an epoxy resin composition containing an epoxy resin and a solvent by a hot-melt method, in which a content of the solvent is 0.02-5 mass%. The epoxy resin is preferably an epoxy resin having a weight average molecular weight of 1,500 or more, or a mixture of an epoxy resin having a weight average molecular weight of 1,500 or more and an epoxy resin having a weight average molecular weight of less than 1,500, where a rate of the epoxy resin having a weight average molecular weight of 1,500 or more per 100 pts.mass of the total epoxy resins is 60 pts.mass or more. The reinforcing fiber is preferably a carbon fiber. Also provided is a fiber-reinforced plastic comprising the fiber-reinforced epoxy resin composite material.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to fiber-reinforced epoxy resin composites and fiber-reinforced plastics using an epoxy resin as a matrix resin, which are suitably used for sports/leisure applications, general industrial applications, aircraft material applications, and the like. .

Fiber-reinforced plastic, which is one of fiber-reinforced composite materials, is lightweight, high-strength, and high-rigidity, and is therefore widely used in sports and leisure applications as well as industrial applications such as automobiles and aircraft.

As a method of producing fiber-reinforced plastics, there is a method of using an intermediate material, ie, a prepreg, in which a reinforcing material made of long fibers (continuous fibers) such as reinforcing fibers is impregnated with a matrix resin. This method has the advantage that it is easy to control the content of the reinforcing fibers in the resulting fiber-reinforced plastic and that the content can be designed to be high. A molded product of fiber-reinforced plastic can be obtained by laminating a plurality of prepregs and heat-curing them.

Conventionally, due to the need for weight reduction, carbon fibers with excellent specific strength and specific modulus are used as reinforcing fibers, and thermosetting epoxy resins with excellent adhesion to carbon fibers are often used as matrix resins.
However, thermosetting epoxy resins tend to be brittle in cured form and have low impact resistance. Therefore, improvement of the impact resistance of fiber-reinforced plastics using them is an issue.

Conventionally, when molding thermosetting fiber reinforced plastics for aircraft, autoclaves are used to harden them under high temperature and high pressure for a long time. The problem was low productivity. In addition, the size of the molded product that can be manufactured is limited by the size of the autoclave, and although it is suitable for the production of high value-added thermosetting carbon fiber reinforced plastics, it is not suitable for mass production of general-purpose products.

For this reason, de-autoclaving, particularly the development of thermoplastic carbon fiber reinforced plastics, is underway. Fiber composites have been proposed.
In general, thermoplastic resin composite materials can be molded in a shorter time than thermosetting resin composite materials, so productivity is high and it can contribute to cost reduction.

JP 2018-193457 A

In Patent Literature 1, a large amount of solvent is used to impregnate the thermoplastic epoxy resin, and it is difficult to control the amount of solvent. In addition, a large amount of voids are generated in the step of volatilizing the solvent, and these voids remain even in the step of molding, causing deterioration in the mechanical properties of the resulting composite material. Furthermore, since a thermoplastic epoxy resin with a low molecular weight is used, the impact resistance is also inferior.

The present invention has been made in view of the above background, and includes a fiber-reinforced epoxy resin composite material that can obtain a fiber-reinforced plastic having extremely few voids and excellent mechanical properties, and a fiber-reinforced epoxy resin composite material that uses this fiber-reinforced epoxy resin composite. An object of the present invention is to provide a fiber-reinforced plastic.

As a result of intensive studies, the present inventors impregnated reinforcing fibers with an epoxy resin composition containing an epoxy resin and a solvent by a hot-melt method, thereby impregnating the reinforcing fibers with the epoxy resin using a very small amount of solvent. As a result, the inventors have found that it is possible to solve the above-mentioned problems and provide a fiber-reinforced plastic having desired performance, thus leading to the present invention.

That is, the gist of the present invention is as follows.

[1] A fiber-reinforced epoxy resin composite obtained by impregnating reinforcing fibers with an epoxy resin composition containing an epoxy resin and a solvent by a hot-melt method, and having a solvent content of 0.02% by mass or more and 5% by mass or less.

[2] The fiber-reinforced epoxy resin composite material according to [1], wherein the epoxy resin has a weight average molecular weight of 1500 or more.

[3] The epoxy resin is a mixture of an epoxy resin having a weight average molecular weight of 1500 or more and an epoxy resin having a weight average molecular weight of less than 1500, and the proportion of the epoxy resin having a weight average molecular weight of 1500 or more in 100 parts by mass of the total epoxy resin is 60. The fiber-reinforced epoxy resin composite material according to [1], which is at least parts by mass.

[4] The fiber-reinforced epoxy resin composite material according to any one of [1] to [3], wherein the reinforcing fibers are carbon fibers.

[5] A fiber-reinforced plastic using the fiber-reinforced epoxy resin composite according to any one of [1] to [4].

[6] A film made of an epoxy resin composition containing an epoxy resin and a solvent, wherein the solvent content in the film is 0.2% by mass or more and 10% by mass or less.

[7] The epoxy resin film according to [6], wherein the epoxy resin has a weight average molecular weight of 1500 or more.

[8] The epoxy resin is a mixture of an epoxy resin having a weight average molecular weight of 1500 or more and an epoxy resin having a weight average molecular weight of less than 1500, and the proportion of the epoxy resin having a weight average molecular weight of 1500 or more in 100 parts by mass of the total epoxy resin is 60. The epoxy resin film according to [6], which is at least parts by mass.

[9] A fiber-reinforced epoxy resin composite obtained by heating and integrating a laminate of the epoxy resin film according to any one of [6] to [8] and a reinforcing fiber assembly.

[10] A method for producing a fiber-reinforced epoxy resin composite comprising reinforcing fibers and an epoxy resin composition, comprising:
(a) preparing an epoxy resin composition containing an epoxy resin and a solvent;
(b) adjusting the temperature of the prepared epoxy resin composition to a range of 20 to 70° C. to form a coating film;
(c) holding the coating film at a temperature of 80 to 180° C. for 5 minutes to 3 hours to volatilize the solvent to form a resin film;
(d) A fiber-reinforced epoxy resin composite having a solvent content of 0.02% by mass or more and 5% by mass or less is produced by impregnating the resin film with the reinforcing fiber under heat and pressure to impregnate the epoxy resin composition. A method for manufacturing a fiber-reinforced epoxy resin composite material.

[11] The method for producing a fiber-reinforced epoxy resin composite according to [10], wherein the epoxy resin has a weight average molecular weight of 1500 or more.

[12] The epoxy resin is a mixture of an epoxy resin having a weight average molecular weight of 1500 or more and an epoxy resin having a weight average molecular weight of less than 1500, and the proportion of the epoxy resin having a weight average molecular weight of 1500 or more in 100 parts by mass of the total epoxy resin is 60. The method for producing a fiber-reinforced epoxy resin composite material according to [10], which is at least parts by mass.

According to the present invention, it is possible to provide a fiber-reinforced plastic having extremely few voids and excellent mechanical properties.

The present invention will be described in detail below.

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 resin composition containing an epoxy resin, a solvent, optionally a curing agent, a curing accelerator, a thermoplastic resin other than the epoxy resin, additives, and the like.
In the present invention, the term "solid content" means the components excluding the solvent, and includes not only solid epoxy resins but also semi-solid and viscous liquid substances.

Moreover, the weight average molecular weight (Mw) of the epoxy resin is a value measured as a polystyrene-equivalent value by gel permeation chromatography.
The "epoxy equivalent" of an epoxy resin is defined as "the mass of an epoxy resin containing one equivalent of an epoxy group" and can be measured according to JISK7236.

The term "impregnation" generally means soaking a "liquid" such as a chemical, resin, or water in a porous material such as cloth, paper, or wood. "Impregnation" means filling the interstices of the reinforcing fibers with an epoxy resin, not limited to the liquid.

[Fiber-reinforced epoxy resin composite]
The fiber-reinforced epoxy resin composite material (also referred to as "prepreg") of the present invention is obtained by impregnating reinforcing fibers with an epoxy resin composition containing an epoxy resin and a solvent by a hot-melt method, and the solvent content is 0. 02% by mass or more and 5% by mass or less, it can be used as a raw material for a fiber-reinforced plastic having remarkably few voids and excellent mechanical properties.

The fiber-reinforced epoxy resin composite material of the present invention can be produced using an epoxy resin composition containing an epoxy resin as described below. Hereinafter, this epoxy resin composition may be referred to as "epoxy resin composition of the present invention", and the epoxy resin in the epoxy resin composition of the present invention may be referred to as "epoxy resin of the present invention".

In addition, in the present invention, a thermoplastic epoxy resin is used as the epoxy resin.
Epoxy resins include thermosetting epoxy resins and thermoplastic epoxy resins. Of these, the thermoplastic epoxy resin is used in the present invention.
Epoxy resins are generally representative of thermosetting resins. Thermosetting epoxy resins have relatively low molecular weights, whereas thermoplastic epoxy resins used in the present invention have thermoplasticity due to their high molecular weights.

<Epoxy resin>
The epoxy resin of the present invention is not particularly limited as long as it is thermoplastic, and known resins can be used.
As the epoxy resin of the present invention, an epoxy resin having a weight average molecular weight of 1500 or more is preferable.
Moreover, the epoxy resin of the present invention may be a mixture of an epoxy resin having a weight average molecular weight of 1,500 or more and an epoxy resin having a weight average molecular weight of less than 1,500.

The content of the epoxy resin in the epoxy resin composition (including solid content and solvent) of the present invention is preferably 25% by mass or more, particularly 30% by mass or more, and 85% by mass or less, particularly 80% by mass or less. . The content of the epoxy resin depends on the viscosity of the epoxy resin, the type of solvent, and the content of the curing agent. It is preferable that the content is equal to or less than the above upper limit, because it is easy to handle when forming a film.

(Epoxy resin with a weight average molecular weight of 1500 or more)
By using an epoxy resin having a weight average molecular weight of 1500 or more as the epoxy resin of the present invention, a fiber-reinforced plastic having excellent impact resistance can be obtained.
As the epoxy resin of the present invention, an epoxy resin having a weight average molecular weight of 1,500 or more and an epoxy resin having a weight average molecular weight of less than 1,500 may be used in combination. In this case, the ratio of the epoxy resin having a weight average molecular weight of 1500 or more to 100 parts by mass of the epoxy resin of the present invention is preferably 60 parts by mass or more, more preferably 65 parts by mass or more, still more preferably 70 parts by mass or more, and particularly preferably It is 90 parts by mass or more, and the upper limit is preferably 100 parts by mass. As the proportion of the epoxy resin having a weight-average molecular weight of 1500 or more is greater than the above lower limit, there is a tendency that a fiber-reinforced plastic having excellent impact resistance can be obtained.

When the epoxy resin of the present invention is composed entirely of epoxy resins having a weight average molecular weight of less than 1500, it tends to be insufficient to develop film formation and impact resistance. However, when the weight-average molecular weight of the epoxy resin exceeds 100,000, the resin tends to be difficult to handle due to its high viscosity.
From the viewpoint of film formation, impact resistance and resin handling, the weight average molecular weight of the epoxy resin having a weight average molecular weight of 1500 or more is preferably 2000 or more, preferably 100,000 or less, more preferably 80,000 or less. .

Also, the epoxy equivalent of the epoxy resin having a weight average molecular weight of 1500 or more is preferably 800 to 50,000 g/eq, particularly preferably 850 to 40,000 g/eq. When the epoxy equivalent is at least the above lower limit, film formation is facilitated and impact resistance is readily exhibited, and when it is at most the above upper limit, handling of the resin is facilitated, which is preferable.

Epoxy resins having a weight average molecular weight of 1500 or more can be produced using a general method for producing thermoplastic epoxy resins. It can be obtained by combining a dihydric phenol compound having an aromatic structure and an alicyclic structure with a bifunctional epoxy resin and subjecting the mixture to a thermal addition reaction in the presence of a catalyst.

The dihydric phenol compound having an aromatic structure and an alicyclic structure is not particularly limited, but 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)-3,3,5- Trimethylcyclohexane and the like can be preferably used. These may use only 1 type and may use 2 or more types together. Among them, bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane is particularly preferred. The bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane used should have a purity of 96% or higher, preferably 98% or higher. If the purity is less than 96%, it may not be possible to achieve a sufficiently high molecular weight.

As the raw material dihydric phenol compound, other dihydric phenol compounds may be used in combination with the above dihydric phenol compounds having an aromatic structure and an alicyclic structure. Any one having two hydroxyl groups bonded to an aromatic ring may be used. Examples thereof include bisphenols such as bisphenol A, bisphenol F, bisphenol S, bisphenol B and bisphenol AD, biphenol, catechol, resorcinol, hydroquinone and dihydroxynaphthalene. In addition, those substituted with non-interfering substituents such as alkyl groups, aryl groups, ether groups and ester groups may also be used. Preferred among these dihydric phenol compounds are bisphenol A, bisphenol F, bisphenol S, 4,4'-biphenol and 3,3',5,5'-tetramethyl-4,4'-biphenol. . Other dihydric phenol compounds may be used alone or in combination of two or more.

When these other dihydric phenol compounds are used in combination, the amount used should be 30% by mass or less in the total dihydric phenol compounds used as raw materials, that is, 70 to 100% by mass of the raw material dihydric phenol compounds should be aromatic. A dihydric phenol compound having a group structure and an alicyclic structure is preferred.

On the other hand, the raw material bifunctional epoxy resin may be any compound having two epoxy groups in the molecule, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, and the like. Bisphenol-type epoxy resin, biphenol-type epoxy resin, alicyclic epoxy resin, catechol, resorcinol, diglycidyl ether of monocyclic dihydric phenol such as hydroquinone, diglycidyl ether of dihydroxynaphthalene, diglycidyl ether of dihydric alcohol, phthalate diglycidyl esters of divalent carboxylic acids such as acids, isophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and the like. In addition, those substituted with non-interfering substituents such as alkyl groups, aryl groups, ether groups and ester groups may also be used. Only one type of these raw material bifunctional epoxy resins may be used, or two or more types may be used in combination.

The equivalent ratio of the raw material bifunctional epoxy resin and the dihydric phenol compound at the time of reaction is preferably epoxy group:phenolic hydroxyl group=1:0.90 to 1.10. Even if this equivalent ratio is smaller than 0.90 or larger than 1.10, it may not be possible to sufficiently increase the molecular weight. Depending on the reaction conditions, etc., if the ratio of epoxy group: phenolic hydroxyl group is less than 1:1, the terminal will be an epoxy group, and if the epoxy group: phenolic hydroxyl group is greater than 1:1, the terminal will be a phenolic hydroxyl group. more likely to become

A commercially available epoxy resin having a weight average molecular weight of 1500 or more may be used.
Commercially available epoxy resins include, but are not limited to, jER1055, jER1004, jER1007, jER1009, jER1010, jER1256, jER4250, jER4275, jER1256B40, jER1255HX30, YX8100BH30, YX6954BH30, YX720 0B35, jER4005P, jER4007P, jER4010P (any Also trade names, manufactured by Mitsubishi Chemical Corporation), EPICLON3050, EPICLON4050, EPICLON7050, EPICLON HM-091, EPICLON HM-101 (all trade names, manufactured by DIC Corporation), YD-903N, YD-904, YD-907 , YD-7910, YD-6020, YP-50, YP-50S, YP-70, ZX-1356-2, FX-316, YDF2004, YDF-2005RD (all trade names, manufactured by Nippon Steel & Sumikin Chemical & Materials Co., Ltd. ) and the like.

Epoxy resins having a weight average molecular weight of 1500 or more may be used alone or in combination of two or more.

(Epoxy resin with a weight average molecular weight of less than 1500)
As the epoxy resin of the present invention, an epoxy resin having a weight average molecular weight of less than 1,500 may be used together with an epoxy resin having a weight average molecular weight of 1,500 or more, as long as the object of the present invention is not impaired. By using an epoxy resin having a weight-average molecular weight of less than 1,500, preferably 1,300 or less, the strength, elastic modulus, heat resistance, and handleability of the resulting fiber-reinforced plastic can be improved.
However, if the molecular weight of the epoxy resin with a weight average molecular weight of less than 1500 is excessively small, the epoxy resin tends to volatilize, and the surface of the release film or release paper repels the epoxy resin, making it impossible to produce a resin film. The lower limit of the weight average molecular weight of the epoxy resin having a molecular weight of less than 1500 is preferably 200 or more, particularly 250 or more.
The epoxy equivalent of the epoxy resin having a weight average molecular weight of less than 1500 is preferably 90-800 g/eq, more preferably 100-750 g/eq. If the epoxy equivalent is at least the above lower limit, it becomes easier to produce a resin film, and if it is at most the above upper limit, heat resistance, strength, and elastic modulus can be improved while imparting toughness, which is preferable.

When an epoxy resin having a weight average molecular weight of 1,500 or more and an epoxy resin having a weight average molecular weight of less than 1,500 are used in combination as the epoxy resin of the present invention, the use of the epoxy resin having a weight average molecular weight of 1,500 or more is effective in obtaining the above effects. The ratio of the epoxy resin having a weight average molecular weight of less than 1500 to 100 parts by mass of the epoxy resin of the present invention is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, still more preferably 30 parts by mass or less, and particularly preferably 10 parts by mass. part or less, and the lower limit is 0 part by mass.

Although the epoxy resin having a weight average molecular weight of less than 1500 is not particularly limited, a difunctional or higher epoxy resin is preferably used. For example, bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, bisphenol S type epoxy resin, bisphenol E type epoxy resin, bisphenol Z type epoxy resin, bisphenol AD type epoxy resin, etc. Glycidylamines such as biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, trisphenolmethane type epoxy resin, tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol type epoxy resin; tetrakis (glycidyloxyphenyl) ethane, tris (glycidyloxy) methane and other glycidyl ether type epoxy resins other than the above, and modified epoxy resins thereof, phenol aralkyl type epoxy resins, alicyclic epoxies, etc. mentioned.
Epoxy resins with three or more functionalities provide superior strength, elastic modulus, and heat resistance. A resin, a cresol novolac type epoxy resin, is preferably used.

Examples of commercially available epoxy resins having a weight average molecular weight of less than 1500 include, but are not limited to, jER825 (epoxy equivalent 175 g/eq), jER827 (epoxy equivalent 185 g/eq), jER828 (epoxy equivalent 189 g/eq), jER834 (epoxy equivalent weight 250 g/eq), jER806 (epoxy equivalent weight 165 g/eq), jER807 (epoxy equivalent weight 170 g/eq), jER604 (epoxy equivalent weight 120 g/eq), jER630 (epoxy equivalent weight 98 g/eq), jER1032H60 (epoxy equivalent weight 169 g/eq) , jER152 (epoxy equivalent 175 g / eq), jER154 (epoxy equivalent 178 g / eq), jER157S70 (epoxy equivalent 210 g / eq), YX-7700 (epoxy equivalent 273 g / eq), YX-8000 (epoxy equivalent 205 g / eq), YX-8800 (epoxy equivalent 179 g/eq), YX-4000 (epoxy equivalent 186 g/eq), YX-7105 (epoxy equivalent 480 g/eq), YX-7400 (epoxy equivalent 440 g/eq) (all trade names, Mitsubishi Chemical Co., Ltd.), YD-127 (epoxy equivalent 185 g / eq), YD-128 (epoxy equivalent 189 g / eq), YDF-170 (epoxy equivalent 170 g / eq), YDPN-638 (epoxy equivalent 180 g / eq), TX-0911 (epoxy equivalent 172 g/eq) (both trade names, manufactured by Nippon Steel & Sumikin Chemical & Materials Co., Ltd.), EPICLON840 (epoxy equivalent 185 g/eq), EPICLON850 (epoxy equivalent 189 g/eq), EPICLON830 (epoxy equivalent 170 g/eq) eq), EPICLON835 (epoxy equivalent 172 g/eq), HP-4032 (epoxy equivalent 150 g/eq), HP-4700 (epoxy equivalent 162 g/eq), HP-4770 (epoxy equivalent 204 g/eq), HP-4750 (epoxy equivalent weight 185 g/eq), HP-7200 (epoxy equivalent weight 265 g/eq), N-730A (epoxy equivalent weight 174 g/eq), N-740 (epoxy equivalent weight 181 g/eq), N-770 (epoxy equivalent weight 187 g/eq), TSR-400 (epoxy equivalent 338 g/eq) (both trade names, manufactured by DIC Corporation), 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) (both trade names, manufactured by Nippon Kayaku Co., Ltd.), MY-0500 (epoxy equivalent 110 g / eq), MY-0600 (epoxy equivalent 106 g / eq), ECN-1299 (epoxy equivalent: 230 g/eq) (both trade names, manufactured by Huntsman Japan Co., Ltd.); E. R331, D.R. E. R354 (epoxy equivalent weight 170 g/eq) (epoxy equivalent weight 187/eq), D.I. E. R332 (epoxy equivalent: 173 g/eq) (both trade names, manufactured by THE DOW CHEMICAL COMPANY) and the like.
Epoxy resins having a weight-average molecular weight of less than 1500 may be used alone or in combination of two or more.

<Solvent>
The epoxy resin composition of the present invention preferably contains a solvent in order to appropriately adjust the viscosity during handling such as impregnation into reinforcing fibers. The solvent is used to ensure handleability and workability when impregnating the reinforcing fiber with the epoxy resin composition of the present invention or when manufacturing the epoxy resin film of the present invention described below. Although there is no particular limitation, the epoxy resin composition of the present invention is usually preferably prepared so that the solid content concentration is 25 to 85% by mass, particularly 30 to 80% by mass.

The solvent contained in the epoxy resin composition of the present invention is not particularly limited. Glycol monomethyl ether acetate, N,N-dimethylformamide, N,N-dimethylacetamide, methanol, ethanol and the like. These solvents can be appropriately used as a mixed solvent of two or more.

<Curing agent>
The epoxy resin composition of the present invention may contain a curing agent. Curing agents are used to impart strength, elastic modulus, heat resistance, adhesion to reinforcing fibers, and the like.
The curing agent used in the present invention is not particularly limited. Acid anhydrides, benzoxazines and the like can be used.

Dicyandiamide has a high melting point and is less compatible with epoxy resins in the low-temperature range. Therefore, when used as a curing agent, an epoxy resin composition having an excellent pot life tends to be obtained, which is preferable. Moreover, the inclusion of dicyandiamide tends to improve the mechanical properties of the cured resin, which is preferable.

When the epoxy resin composition of the present invention contains dicyandiamide as a curing agent, the content thereof is the activity of dicyandiamide with respect to the total number of moles of epoxy groups possessed by the epoxy resin of the present invention contained in the epoxy resin composition of the present invention. It is preferable that the amount is such that the number of moles of hydrogen is 0.4 to 1 times. By setting this molar ratio to 0.4 times or more, there is a tendency to obtain a cured product having good heat resistance and good mechanical properties (that is, high strength and elastic modulus). In addition, by setting it to 1 time or less, there is a tendency to obtain a cured product having good mechanical properties (that is, excellent plastic deformation ability and impact resistance). Furthermore, by increasing the number of moles of active hydrogen in the dicyandiamide to 0.5 to 0.8 times, the heat resistance of the cured product tends to be more excellent, which is more preferable.

Commercially available products of dicyandiamide include, but are not limited to, DICY7, DICY15 (both trade names, manufactured by Mitsubishi Chemical Corporation) and DICYANEX1400F (trade name, manufactured by Air Products Co., Ltd.).

Urea is not particularly limited as long as it has a dimethylureido group in the molecule and generates an isocyanate group and dimethylamine by heating at a high temperature, and these activate the epoxy resin of the present invention. Examples thereof 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 dimethyl urea is preferable because it tends to increase the curing speed and the heat resistance and bending strength of the cured product.
As aromatic dimethylurea, for example, phenyldimethylurea, methylenebis(phenyldimethylurea), and tolylenebis(dimethylurea) 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 Dimethyl urea obtained from and the like. Among these, DCMU, MBPDMU, TBDMU, and PDMU are more preferable from the viewpoint of curing acceleration ability and imparting heat resistance to a resin cured product. These may be used individually by 1 type, and may be used in combination of 2 or more type.

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

Commercially available ureas can also be used. Commercial products of DCMU include, for example, DCMU
-99 (trade name, manufactured by Hodogaya Chemical Industry Co., Ltd.) and the like, but are not limited thereto.
Commercially available products of MBPDMU include, for example, Technicure MDU-11 (trade name, manufactured by A&C Catalysts); Omicure 52 (trade name, manufactured by PIT Japan Co., Ltd.). It is not limited.
Commercially available products of PDMU include, but are not limited to, Omicure 94 (trade name, manufactured by PI Japan Co., Ltd.).
Commercially available products of TBDMU include, for example, Omicure 24 (trade name, manufactured by PI Japan Co., Ltd.) and U-CAT 3512T (trade name, manufactured by San-Apro Co., Ltd.). It is not limited.
Commercially available products of aliphatic dimethyl urea include, but are not limited to, U-CAT 3513N (trade name, manufactured by San-Apro Co., Ltd.).

When the epoxy resin composition of the present invention contains urea as a curing agent, the content thereof is 1 to 15 parts by mass based on 100 parts by mass of the epoxy resin of the present invention contained in the epoxy resin composition of the present invention. Preferably, 2 to 10 parts by mass is more preferable. When the urea content is 1 part by mass or more, the epoxy resin contained in the epoxy resin composition can be sufficiently cured and accelerated, and mechanical properties and heat resistance tend to be improved. On the other hand, when the content of ureas is 15 parts by mass or less, the resulting cured product tends to maintain high toughness.

The imidazoles may be imidazole, and imidazole adducts, inclusion imidazoles, microcapsule-type imidazoles, imidazole compounds coordinated with stabilizers, and the like can also be used.
These have nitrogen atoms with lone pairs of electrons in their structure, which can activate the epoxy groups of the epoxy resins of the present invention and accelerate curing and hardening.

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- phenylimidazolium 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-hydroxymethylimidazole and the like, but these include It is not limited.
Adduct treatment, inclusion treatment with foreign molecules, microencapsulation treatment, or imidazole coordinated with a stabilizer is a modification of the imidazole. These can be hardened or accelerated while exhibiting excellent pot life in low-temperature regions by reducing the activity of imidazole by adduct treatment, inclusion treatment with foreign molecules, microencapsulation treatment, or by coordinating a stabilizer. Highly capable.

You may use a commercial item as imidazole. Commercial products of imidazole include 2E4MZ, 2P4MZ, 2PZ-CN, C11Z-CNS, C11Z-A, 2MZA-PW, 2MA-OK, 2P4MHZ-PW, and 2PHZ-PW (all trade names, manufactured by Shikoku Kasei Co., Ltd.). include, but are not limited to.
Commercially available imidazole adducts include, for example, PN-50, PN-50J, PN-40, PN-40J, PN-31, and PN-23, which have a ring-opening addition structure of an imidazole compound to an epoxy group of an epoxy resin. , and PN-H (both trade names, manufactured by Ajinomoto Fine-Techno Co., Inc.), but are not limited to these.
Commercial products of clathrate imidazole include, for example, TIC-188, KM-188, HIPA-2P4MHZ, NIPA-2P4MHZ, TEP-2E4MZ, HIPA-2E4MZ, and NIPA-2E4MZ (all trade names, manufactured by Nippon Soda Co., Ltd.). include, but are not limited to.
Examples of commercial products of microcapsule-type imidazole include Novacure HX3721, HX3722, HX3742, HX3748 (all trade names, manufactured by Asahi Kasei E-materials); LC-80 (trade name, manufactured by A&C Catalysts). However, it is not limited to these.

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

When the epoxy resin composition of the present invention contains imidazoles as a curing agent, the content thereof is 1 to 15 parts by mass with respect to 100 parts by mass of the epoxy resin of the present invention contained in the epoxy resin composition of the present invention. Preferably, 2 to 10 parts by mass is more preferable. When the imidazole content is 1 part by mass or more, the epoxy resin contained in the epoxy resin composition tends to exhibit sufficient curing, curing acceleration, and heat resistance. On the other hand, when the content of imidazoles is 15 parts by mass or less, there is a tendency that a cured product having excellent mechanical properties can be obtained.

Examples of aromatic amines 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',5,5'-tetraisopropyl-4,4'-diamino Diphenylmethane, 3,3'-di-t-butyl-5,5'-diisopropyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetra-t-butyl-4,4'-diamino diphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine and the like, but these include It is not limited. Among them, it is preferable to use 4,4'-diaminodiphenylsulfone and 3,3'-diaminodiphenylsulfone, which are excellent in heat resistance and elastic modulus, and give a cured product having a small decrease in heat resistance due to linear expansion coefficient and moisture absorption. . 4,4'-Diaminodiphenylsulfone is also preferable in that it can maintain the tack life of the prepreg for a long period of time. Although 3,3'-diaminodiphenylsulfone may be inferior to 4,4'-diaminodiphenylsulfone in terms of 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. . Also, it is preferable to mix 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 alone, or may be used by appropriately blending them.

Commercially available aromatic amines may be used. Commercially available products of 4,4'-diaminodiphenylsulfone include Seikacure S (active hydrogen equivalent 62 g/eq, trade name, manufactured by Wakayama Seika Kogyo Co., Ltd.), Sumicure S (active hydrogen equivalent 62 g/eq, trade name, Sumitomo Chemical Co., Ltd.), and commercial products of 3,3′-diaminodiphenylsulfone include 3,3′-DAS (active hydrogen equivalent 62 g/eq, trade name, manufactured by Mitsui Chemicals Fine Co., Ltd.). It is not limited to these.
In addition, commercially available aromatic amines include MDA-220 (active hydrogen equivalent 50 g/eq, trade name, manufactured by Mitsui Chemicals, Inc.), "jER Cure (registered trademark)" W (active hydrogen equivalent 45 g/eq, Mitsubishi Chemical Corporation), Lonzacure (registered trademark) M-DEA (active hydrogen equivalent 78 g / eq), "Lonzacure (registered trademark)" M-DIPA (active hydrogen equivalent 92 g / eq), "Lonzacure (registered trademark)" Examples thereof include, but are not limited to, M-MIPA (active hydrogen equivalent 78 g/eq) and “Lonzacure®” DETDA 80 (active hydrogen equivalent 45 g/eq) (manufactured by Lonza).

When the epoxy resin composition of the present invention contains an aromatic amine as a curing agent, the content thereof, particularly in diaminodiphenylsulfone, in terms of the number of active hydrogen equivalents of the amino group, is the same as that of the epoxy resin composition of the present invention. It is preferably 0.5 to 1.5 times, more preferably 0.6 to 1.4 times, the epoxy equivalent number of the total epoxy resin contained in. By setting it to this range, the elastic modulus, toughness and heat resistance of the cured product to be obtained tend to be within favorable ranges.

Examples of acid anhydrides include dicarboxylic acid compounds having one cyclic acid anhydride group (—C(O)OC(O)—) in one molecule and two cyclic acid anhydride groups in one molecule. tetracarboxylic acid compounds having Specifically, dodecenyl succinic anhydride, polyadipic anhydride, polyazelaic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhimic anhydride, hexahydrophthalic anhydride, phthalic anhydride, anhydride trimellitic acid, 3-acetamidophthalic anhydride, 4-pentene-1,2-dicarboxylic anhydride, 6-bromo-1,2-dihydro-4H-3,1-benzoxazine-2,4-dione, 2,3-anthracenedicarboxylic anhydride, benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride and the like. These may be used individually by 1 type, or may use 2 or more types together.

When the epoxy resin composition of the present invention contains an acid anhydride as a curing agent, the content of the acid anhydride with respect to the epoxy equivalent number of the epoxy resin of the present invention in the epoxy resin composition of the present invention. is preferably 0.5 to 1.5, more preferably 0.6 to 1.4, even more preferably 0.7 to 1.3.

Phenols generally increase the cross-linking density of the cured product, and by using them, a cured product having excellent heat resistance, moisture resistance, chemical resistance, etc. can be obtained.
Commercially available phenols may be used, such as TD-2131, TD-2106, TD-2093, TD-2091, TD-2090, VH-4150, VH-4170, KH-6021, KA-1160, KA-1163, KA-1165 (all trade names, manufactured by DIC Corporation), etc., MR-970N, MR-600, MR-970, MR-506, MR-860, MR-3307, MR-583, MR-757, MR- 508, MR-110, MR-750, MR-550M, MR-5809, MR-750N, M-1, MR-552, MR-130, MR-2015, MR-320, MR-2014, MR-2018, MR-3413, MR-3405, MR-506C, MR-3424, MWR-204, MWR-102E, MWR-202L, MR-332, MWR-102EM, MWR-1223, MWR-202, MWR-2205, MWR- 102G, MWR-1201, MW-201 (all trade names, manufactured by Meiwa Kasei Co., Ltd.) and the like, but are not limited thereto.

When the epoxy resin composition of the present invention contains a phenol as a curing agent, the content thereof is such that the active hydrogen equivalent number of the hydroxyl group of the phenol is the epoxy resin of the present invention contained in the epoxy resin composition of the present invention. The amount is preferably 0.5 to 1.5 times, more preferably 0.6 to 1.4 times, the epoxy equivalent number of . By setting this ratio within the above range, the elastic modulus, toughness and heat resistance of the resulting cured product tend to be within favorable ranges.

Specific examples of organic phosphine compounds include tri-n-propylphosphine, tri-n-butylphosphine, triphenylphosphine, tetramethylphosphonium bromide, tetramethylphosphonium iodide, tetramethylphosphonium hydroxide, trimethylcyclohexylphosphonium chloride, trimethyl Cyclohexylphosphonium bromide, trimethylbenzylphosphonium chloride, trimethylbenzylphosphonium bromide, tetraphenylphosphonium bromide, triphenylmethylphosphonium bromide, triphenylmethylphosphonium iodide, triphenylethylphosphonium chloride, triphenylethylphosphonium bromide, triphenylethylphosphonium iodide , triphenylbenzylphosphonium chloride, triphenylbenzylphosphonium bromide, and the like, but are not limited thereto.

When the epoxy resin composition of the present invention contains an organic phosphine compound as a curing agent, the content thereof is 0.1 to 5 parts per 100 parts by mass of the epoxy resin of the present invention contained in the epoxy resin composition of the present invention. Part by weight is preferred, and 0.5 to 3 parts by weight is more preferred. When the content of the organic phosphine compound is 0.1 parts by mass or more, the epoxy resin contained in the epoxy resin composition tends to be sufficiently cured, accelerated curing, and heat resistance. On the other hand, when the content of the organic phosphine compound is 5 parts by mass or less, there is a tendency that a cured product having excellent mechanical properties can be obtained.

With benzoxazines, the oxazine ring is opened by heat to form a phenolic hydroxyl group, and like phenols, the crosslink density of the cured product is generally increased. A cured product with excellent properties and chemical resistance can be obtained.
Available benzoxazines include benzoxazine Fa, benzoxazine Pd (both trade names, manufactured by Shikoku Kasei Kogyo Co., Ltd.), JBZ-OP100N, JBZ-BP100N (both trade names, JFE Chemical Co., Ltd.). company), BF-BXZ, BS-BXZ (both trade names, manufactured by Konishi Kagaku Kogyo Co., Ltd.), CR-276 (both trade names, manufactured by Tohoku Kako Co., Ltd.), etc., but are not limited to these. .

When the epoxy resin composition of the present invention contains benzoxazines as a curing agent, the content thereof is such that the number of active hydrogen equivalents of the hydroxyl groups generated when the benzoxazines are heated is equal to the number of active hydrogen equivalents of the epoxy resin composition of the present invention. The amount is preferably 0.3 to 3.0 times, more preferably 0.4 to 2.5 times, the epoxy equivalent number of the epoxy resin of the present invention contained in preferable. By setting this ratio within the above range, the elastic modulus, toughness and heat resistance of the resulting cured product tend to be within favorable ranges.

<Thermoplastic resin>
The epoxy resin composition of the present invention may optionally contain a thermoplastic resin other than the epoxy resin for the purpose of imparting functions such as resin flow control and toughness during impregnation of reinforcing fibers.

Examples of thermoplastic resins other than epoxy resins include polyamides, polyesters, polycarbonates, polyethersulfones, polyphenylene ethers, polyphenylene sulfides, polyetheretherketones, polyetherketones, polyimides, polytetrafluoroethylenes, polyethers, polyolefins, and liquid crystal polymers. , polyarylate, polysulfone, polyacrylonitrile styrene, polystyrene, polyacrylonitrile, polymethyl methacrylate, ABS, AES, ASA, polyvinyl chloride, polyvinyl formal resin, block polymer and the like, but are not limited thereto.

Among these, polyether sulfone and polyvinyl formal resin are preferable because they are excellent in resin flow controllability and the like. In addition, polyether sulfone is preferable from the viewpoint of further enhancing the heat resistance and flame retardancy of the epoxy resin composition, and polyvinyl formal resin is suitable for improving the tackiness of the obtained prepreg without impairing the heat resistance of the epoxy resin composition. It is preferable from the viewpoint that the range can be easily controlled and the adhesion between the reinforcing fiber and the epoxy resin composition is improved. Block polymers are preferred because they improve toughness and impact resistance.

Examples of polyvinyl formal resins include 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) (both trade names, manufactured by JNC Corporation), but are not limited thereto.

When the obtained fiber-reinforced plastic requires heat resistance exceeding 180° C., polyethersulfone and polyetherimide are preferably used as the thermoplastic resin. Specifically, as polyether sulfone, Sumika Excel (registered trademark) 3600P (average molecular weight: 16,400), Sumika Excel 5003P (average molecular weight: 30,000), Sumika Excel 5200P (average molecular weight: 35,000), and Sumika Excel 7600P (average molecular weight: 45,300) (manufactured by Sumitomo Chemical Co., Ltd.). As polyetherimide, ULTEM1000 (average molecular weight: 32,000), ULTEM1010 (average molecular weight: 32,000), ULTEM1040 (average molecular weight: 20,000) (all trade names, manufactured by SABIC Innovative Plastics Co., Ltd.), etc. include, but are not limited to.

Block polymers include Nanostrength M52, Nanostrength M52N, Nanostrength M22, Nanostrength M22N, Nanostrength 123, Nanostrength 250, Nanostrength 012, Nanostrength E20, Nanostrength E4. 0 (both trade names, manufactured by ARKEMA), TPAE-8, TPAE-10, TPAE-12, TPAE-23, TPAE-31, TPAE-38, TPAE-63, TPAE-100, PA-260 (all trade names, manufactured by T&K TOKA) and the like, but not limited thereto.

These thermoplastic resins may be used singly or in combination of two or more.

When the epoxy resin composition of the present invention contains a thermoplastic resin other than the epoxy resin, the content thereof should be 15 parts by mass or less per 100 parts by mass of the epoxy resin of the present invention in the epoxy resin composition of the present invention. Preferably, 10 parts by mass or less is more preferable. When the content of the thermoplastic resin is 15 parts by mass or less, resin flow control and physical property improvement effects tend to be exhibited satisfactorily while maintaining impact resistance.

<Optional component>
If necessary, the epoxy resin composition of the present invention may contain various known additives within a range that does not impair the effects of the present invention. Antioxidants and light stabilizers can also be added to avoid deterioration and deterioration.

Specific examples thereof include various commercially available Sumilizer BHT, Sumilizer S, Sumilizer BP-76, Sumilizer MDP-S, Sumilizer GM, Sumilizer BBM-S, Sumilizer WX-R, and Sumilizer manufactured by Sumitomo Chemical Co., Ltd. NW, Sumilizer BP-179, Sumilizer BP-101, Sumilizer GA-80, Sumilizer TNP, Sumilizer TPP-R, Sumilizer P-16; Asahi Denka Kogyo Co., Ltd. Adekastab AO-20, Adekastab AO-30, Adekastab AO- 40, ADEKA STAB AO-50, ADEKA STAB AO-60AO-70, ADEKA STAB AO-80, ADEKA STAB AO-330, ADEKA STAB PEP-4C, ADEKA STAB PEP-8, ADEKA STAB PEP-24G, ADEKA STAB PEP-36, ADEKA STAB HP-10, ADEKA STAB 2112, AdeCastab 260, Adeca Stab 522A, Adecus Stab 329k, Adecus Stab 1500, Adecastab C, Adecastab 135A, Adeca Stab 3010; Chibu Specialty Chemicals Co., Ltd. , Chinubin 622, Chinubin 111, Chinubin 123, Chinubin 292; Fancryl FA-711M and FA-712HM manufactured by Hitachi Chemical Co., Ltd.;

When the epoxy resin composition of the present invention contains these antioxidants and light stabilizers, the amount added is not particularly limited. On the other hand, it is preferably in the range of 0.001 to 20 parts by mass, more preferably in the range of 0.01 to 15 parts by mass.

Other additives include thermosetting elastomers, thermoplastic elastomers, flame retardants (e.g., phosphorus-containing epoxy resins, red phosphorus, phosphazene compounds, phosphates, phosphate esters, etc.), silicone oils, wetting and dispersing agents, and antifoaming agents. agents, defoaming agents, natural waxes, synthetic waxes, metal salts of straight-chain fatty acids, acid amides, esters, paraffins and other release agents, crystalline silica, fused silica, calcium silicate, alumina, calcium carbonate , powders such as talc and barium sulfate, inorganic fillers such as metal oxides, metal hydroxides, glass fibers, carbon nanotubes and fullerenes, organic fillers such as carbon fibers and cellulose nanofibers, inorganic fillers with surface organic treatment, etc. , carbon black, colorants such as red iron oxide, silane coupling agents, and known additives such as conductive materials. Further, if necessary, a slip agent, a leveling agent, a polymerization inhibitor such as hydroquinone monomethyl ether, an ultraviolet absorber, and the like may be added.
These may be used individually by 1 type, and may be used together in combination of 2 or more types.

<Method for producing epoxy resin composition>
The epoxy resin composition of the present invention is not limited to the following, but can be obtained, for example, by mixing each component described above.
Examples of a method for mixing each component include a method using a mixer such as a three-roll mill, planetary mixer, kneader, homogenizer, and homodisper.

<Reinforcing fiber>
The reinforcing fiber is not particularly limited, and may be appropriately selected from known reinforcing fibers constituting the fiber-reinforced composite material according to the application. Specific examples of reinforcing fibers include various inorganic or organic fibers such as carbon fibers, aramid fibers, nylon fibers, high-strength polyester fibers, glass fibers, boron fibers, alumina fibers, and silicon nitride fibers. Among these, from the viewpoint of specific strength and specific elasticity, carbon fiber, aramid fiber, glass fiber, boron fiber, alumina fiber, and silicon nitride fiber are preferable, and from the viewpoint of mechanical properties, heat resistance, electromagnetic wave shielding, and lightness, carbon fiber Fibers are particularly preferred. When carbon fibers are used as reinforcing fibers, they may be surface-treated with a metal.
One type of these reinforcing fibers may be used alone, or two or more types may be used in combination.

From the viewpoint of the rigidity of the fiber-reinforced plastic obtained using the fiber-reinforced epoxy resin composite of the present invention, the tensile strength of the carbon fiber strand used as the reinforcing fiber is preferably 1 to 9 GPa, more preferably 1.5 to 9 GPa. The tensile modulus is preferably 150 to 1,000 GPa, more preferably 200 to 1,000 GPa.
Here, the tensile strength and tensile modulus of the carbon fiber strand are values measured according to JIS R 7601:1986.

The form of the reinforcing fibers is not particularly limited, and any form that is used as a base material for ordinary fiber-reinforced composite materials can be adopted. It may be a non-woven fabric, or a non-crimped fabric (NCF).

Although there is no particular limitation on the basis weight of the carbon fiber aggregate used as reinforcing fibers, it is preferably about 30 to 1000 g/m ² , particularly about 50 to 800 g/m ² . If the basis weight of the carbon fiber aggregate is at least the above lower limit, the number of times of lamination can be appropriately maintained, and if it is at most the above upper limit, the epoxy resin composition can be easily impregnated and the drape property can be maintained.

<Method for producing fiber-reinforced epoxy resin composite>
The fiber-reinforced epoxy resin composite material of the present invention can be produced by impregnating reinforcing fibers, preferably an aggregate of reinforcing fibers, with the epoxy resin composition of the present invention.

In general, methods for impregnating a reinforcing fiber assembly with an epoxy resin include, for example, a wet method in which a low-viscosity epoxy resin composition having a relatively high solvent content is impregnated, and a low-viscosity method in which an epoxy resin composition is heated to reduce its viscosity. Although a known method such as a hot melt method (dry method) is known, in which a reinforcing fiber is impregnated with an epoxy resin composition containing an epoxy resin and a solvent, the reinforcing fiber is impregnated by the hot melt method. The hot-melt method includes a method in which a reinforcing fiber is directly impregnated with a resin composition whose viscosity has been reduced by heating, and a method in which a resin composition is coated on release paper or the like to prepare a film, and then this film is applied. There is a method of impregnating the reinforcing fibers with an epoxy resin by stacking them on both sides or one side of an aggregate of reinforcing fibers and applying heat and pressure.

The fiber-reinforced epoxy resin composite material of the present invention is preferably produced using the above-described film among the hot-melt methods. According to this method, unlike the wet method, the residual solvent in the fiber-reinforced epoxy resin composite can be significantly reduced. It can be made into a composite material, and by using this fiber-reinforced epoxy resin composite material, a fiber-reinforced plastic having extremely few voids and excellent mechanical properties can be obtained.

<Solvent content of fiber reinforced epoxy resin composite>
The solvent content of the fiber-reinforced epoxy resin composite material of the present invention is 0.02% by mass or more and 5% by mass or less, preferably 0.05%, when the mass of the entire fiber-reinforced epoxy resin composite material is 100% by mass. It is more than mass % and below 4 mass %. When the solvent content in the fiber-reinforced epoxy resin composite exceeds 5% by mass, voids are generated in the fiber-reinforced plastic obtained by using this fiber-reinforced epoxy resin composite due to the residual solvent. is the starting point of fracture when stress is concentrated, so a fiber-reinforced plastic with excellent mechanical properties cannot be obtained. Although it is preferable that the solvent content of the fiber-reinforced epoxy resin composite material of the present invention is as low as possible, a solvent content of 0.02% by mass or more facilitates impregnation.
The solvent content in the fiber-reinforced epoxy resin composite can be determined by heating in an oven at 200° C. for 1.5 hours to volatilize the solvent and measuring the weight. The solvent content was also determined by this method in the examples given later.

<Resin and reinforcing fiber content of fiber-reinforced epoxy resin composite>
The resin content (content of resin components containing epoxy resin) of the fiber-reinforced epoxy resin composite of the present invention is 15 to 50% by mass when the mass of the entire fiber-reinforced epoxy resin composite is 100% by mass. is preferred, 20 to 45% by mass is more preferred, and 25 to 40% by weight is even more preferred. If the resin content is 15% by mass or more, sufficient adhesion between the reinforcing fiber and the resin component such as epoxy resin can be ensured, and if it is 50% by mass or less, mechanical properties tend to be kept high. .

[Epoxy resin film]
The epoxy resin film of the present invention is a film made of an epoxy resin composition containing an epoxy resin and a solvent, and is characterized in that the solvent content in the film is 0.2% by mass or more and 10% by mass or less.

The epoxy resin film of the present invention is used as an intermediate material for producing the fiber-reinforced epoxy resin composite of the present invention. It is suitably used as a film for producing epoxy resin composites.
That is, the fiber-reinforced epoxy resin composite material of the present invention can be produced by attaching the epoxy resin film of the present invention to a reinforcing fiber substrate, impregnating it with a resin, and optionally curing it with a curing agent. The epoxy resin film of the present invention is also useful as a surface protective film or adhesive film.

The method for producing the epoxy resin film of the present invention is not particularly limited, but a method of applying the epoxy resin composition of the present invention to the surface of a substrate such as a PET film or release paper to form a film is preferred. Examples of film forming methods include roll coating, reverse coating, comma coating, knife coating, die coating, gravure coating, melt extrusion molding, solution casting, T-die, and calendering. By using a co-extrusion method or a lamination method, it is possible to increase the thickness or laminate different resin compositions for production.

In this manner, when the epoxy resin film of the present invention is produced, the drying and/or curing reaction of the epoxy resin composition of the present invention may proceed to such an extent that the shape can be maintained by heating or the like. When the epoxy resin composition contains a solvent, most of the solvent is removed by a technique such as heating, reduced pressure, air drying, etc., and the total amount of the epoxy resin film is 100% by mass. The solvent is removed so that the solvent content is between 0.2% and 10% by weight, especially between 0.4% and 8% by weight. When the solvent content of the epoxy resin film exceeds 10% by mass, the solvent content of the resulting fiber-reinforced epoxy resin composite exceeds 5% by mass, resulting in a fiber-reinforced plastic with few voids and excellent mechanical properties. can no longer be obtained. The solvent content of the epoxy resin film of the present invention is preferably as small as possible, but if it is less than 0.2% by mass, impregnation with the epoxy resin composition becomes difficult.
The solvent content of the epoxy resin film can be determined in the same manner as the solvent content of the fiber-reinforced epoxy resin composite.

Although the thickness of the epoxy resin film of the present invention is not particularly limited, it is preferably 10 μm to 500 μm, more preferably 20 μm to 400 μm, and particularly preferably 30 μm to 300 μm. If the thickness of the epoxy resin film is at least the above lower limit, the film can be produced without repelling the resin, and if the thickness is below the above upper limit, the shape of the film can be maintained during film production, which is preferable.

The epoxy resin film of the present invention can be imparted with new functions by physical surface treatment, chemical surface treatment, coating, or the like, if necessary.
can.

In order to produce the fiber-reinforced epoxy resin composite material of the present invention using the epoxy resin film of the present invention, for example, the epoxy resin film of the present invention is laminated on one or both surfaces of an assembly of reinforcing fibers, and A method in which the epoxy resin film and the reinforcing fiber are integrated by heating at about 200° C. can be mentioned. During this heating, a pressure of about 0.5 to 10 MPa may be applied, and a vacuum may be drawn to promote the impregnation of the resin.

[Fiber-reinforced plastic]
The fiber-reinforced plastic of the present invention is produced using the fiber-reinforced epoxy resin composite of the present invention. The fiber-reinforced plastic of the present invention can be produced according to a general method for producing a fiber-reinforced plastic using a prepreg, except that the fiber-reinforced epoxy resin composite of the present invention is used as a prepreg.
That is, for example, after laminating the fiber-reinforced epoxy resin composite material of the present invention, there is a method of molding by heat-curing the epoxy resin while applying pressure to the laminate depending on the case. When laminating prepregs, the fiber-reinforced epoxy resin composite material of the present invention may be combined with a fiber-reinforced sheet impregnated with another thermoplastic resin.

When the fiber-reinforced plastic of the present invention is cured, it may be cured at, for example, 23 to 250° C., although it may vary depending on the ingredients and amounts in the epoxy resin composition used in the production of the fiber-reinforced epoxy resin composite and the shape of the compound. 5 minutes to 24 hours.

Examples of the method for molding the fiber-reinforced plastic of the present invention include press molding, autoclave molding, bagging molding, wrapping tape, internal pressure molding, and sheet wrap molding, but are limited to these molding methods. isn't it.

The wrapping tape method is a method of winding a prepreg around a metal core such as a mandrel to form a tubular body made of fiber-reinforced plastic, and is preferably used when producing rod-shaped bodies such as golf shafts and fishing rods. 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 to the prepreg, the resin is heated and cured in an oven, and then the core bar is formed. is extracted to obtain a fiber-reinforced plastic tubular body.

In the internal pressure molding method, a preform obtained by winding a prepreg around an internal pressure imparting body such as a thermoplastic resin tube is set in a mold, and then a high-pressure gas is introduced into the internal pressure imparting body to apply pressure at the same time. In this method, the mold is heated and molded. The method includes golf shafts, bats,
It is preferably used when molding complex shaped objects such as rackets for tennis, badminton, and the like.

The fiber-reinforced plastic of the present invention 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 rackets, hockey sticks, and ski poles. Further, 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, papermaking rollers, roofing materials, cables, and repair and reinforcement materials, etc. It is preferably used for

[Structure]
A structure can be obtained from the fiber-reinforced plastic of the present invention. This structure may consist solely of the fiber-reinforced plastic of the present invention, or may consist of the fiber-reinforced plastic of the present invention and other materials (e.g., metal, injection-molded thermoplastic resin members, etc.). It may be
Since this structure is partially or wholly composed of the fiber-reinforced plastic made of the fiber-reinforced epoxy resin composite of the present invention, it is excellent in flame retardancy and heat resistance, and is also excellent in mechanical properties.
This structure can be applied not only to the use of the fiber-reinforced plastic of the present invention, but also to interior members of aircraft and automobiles, housings for electrical and electronic equipment, and the like.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[material]
Raw materials used in the following examples, comparative examples and reference examples are as follows.

<Epoxy resin>
jER1256: solid bisphenol A type epoxy resin, Mw: about 50,000, epoxy equivalent: about 8,000 g/eq, manufactured by Mitsubishi Chemical Corporation jER1055: solid bisphenol A type epoxy resin, Mw: about 1,600, epoxy equivalent: About 850 g / eq, manufactured by Mitsubishi Chemical Corporation jER1003: solid bisphenol A type epoxy resin, Mw: about 1,300, epoxy equivalent: about 720 g / eq, manufactured by Mitsubishi Chemical Corporation

<Solvent>
methyl ethyl ketone

<Reinforcing fiber>
Pyrofil TR3110M: carbon fiber cloth, fiber basis weight: 200 g/m ² , manufactured by Mitsubishi Chemical Corporation

[Example 1]
Using jER1256 as the epoxy resin and methyl ethyl ketone as the solvent, an epoxy resin composition was prepared as follows.
First, an epoxy resin (solid) and a solvent (liquid) were weighed in a container so that the solid concentration was 40% by mass, mixed and dissolved to obtain a 40% by mass methyl ethyl ketone solution of jER1256.
This solution is applied onto a silicone-treated PET film with a slot die coating device (manufactured by Kadoiseiki Co., Ltd.) at a coating speed of 2.0 m/min, dried at a drying temperature of 150 ° C. for 6 minutes, and the thickness is An epoxy resin film of 50 μm jER1256 was obtained. 2.1% by mass of solvent remained in this epoxy resin film (solvent content: 2.1% by mass).
This epoxy resin film is laminated on both sides of a carbon fiber cloth (Pyrofil TR3110M) and impregnated while being vacuumed by a press set to 160° C. in advance to obtain a fiber-reinforced epoxy resin composite material having a resin content of 37.3% by mass ( prepreg) was obtained. The solvent content in this prepreg was 0.7% by mass.

[Example 2]
A prepreg was produced in the same manner as in Example 1, except that jER1055 was used as the epoxy resin.

[Comparative Example 1]
Using jER1256 as the epoxy resin and methyl ethyl ketone as the solvent, an epoxy resin composition was prepared as follows.
First, an epoxy resin (solid) and a solvent (liquid) were weighed into a container so that the solid concentration was 20% by mass, mixed and dissolved to obtain a 20% by mass methyl ethyl ketone solution of jER1256.
Subsequently, a carbon fiber cloth (Pyrofilm TR3110M) was cut to a length of 20 mm and a width of 130 mm. C. for 20 minutes and the solvent was removed. After that, impregnation was performed at 150 kN and 160° C. for 30 minutes while vacuuming with a press machine to obtain a prepreg having a resin content of 37.3% by mass. The solvent content in the obtained prepreg was 0.4% by mass.

[Reference example 1]
A prepreg was produced in the same manner as in Example 1, except that jER1003 was used as the epoxy resin.

The following evaluations were performed on the produced prepregs. Table 1 shows the results.

[Void number evaluation of prepreg]
The number of voids present in each 5 mm square of the obtained prepreg was observed with an optical microscope. Less than 100 voids per observed area were rated as ◯, and 100 or more voids per unit area were rated as x. If the number of voids is less than 100 per area, the voids disappear by molding while vacuuming with a press during production of the reinforced fiber plastic, and a reinforced fiber plastic with excellent mechanical properties can be obtained. If the number of voids per area is 100 or more, the voids will not be completely eliminated even if molding is carried out while vacuuming during production of the reinforced fiber plastic, and the voids will remain, resulting in a reinforced fiber plastic with low mechanical properties.

[Peelability evaluation of prepreg]
Two sheets of the obtained prepreg were laminated, and after standing for 30 minutes at 55° C. under a load of 58 g/cm ² , it was confirmed whether the prepreg peeled off. Things are x.
A prepreg that peels off is preferable because the prepregs do not adhere to each other when the prepreg is laminated by mistake and heat is applied. If the prepregs are not peeled off, the prepregs will adhere to each other when the prepregs are laminated by mistake and heat is applied, which is not preferable.

As shown in Table 1, in Example 1 using the hot-melt method, a void-free prepreg and fiber-reinforced plastic were obtained despite the large amount of solvent in the prepreg compared to Comparative Example 1 using the wet method in which voids were generated. was taken. Moreover, although Example 2 peeled, Reference Example 1 did not peel. In Reference Example 1, since the weight average molecular weight of the epoxy resin used was low, the prepreg was fused.

By using the fiber-reinforced epoxy resin composite material of the present invention, it is possible to obtain a fiber-reinforced plastic having extremely few voids and excellent mechanical properties. Therefore, according to the present invention, it is possible to provide a wide range of fiber-reinforced plastic molded articles having excellent mechanical properties, such as molded articles for sports and leisure applications such as golf club shafts, and molded articles for industrial applications such as aircraft.

Claims (6)

An epoxy resin film comprising an epoxy resin composition containing an epoxy resin and a solvent, wherein the solvent content in the film is 0.2% by mass or more and 10% by mass or less. 7. The epoxy resin film according to claim 6, wherein the epoxy resin has a weight average molecular weight of 1500 or more. 3. The epoxy resin film according to claim 2, wherein the epoxy resin having a weight average molecular weight of 1500 or more has an epoxy equivalent of 800 to 50,000 g/eq. The epoxy resin is a mixture of an epoxy resin having a weight average molecular weight of 1500 or more and an epoxy resin having a weight average molecular weight of less than 1500, and the proportion of the epoxy resin having a weight average molecular weight of 1500 or more in 100 parts by weight of the total epoxy resin is 60 parts by weight or more. 4. The epoxy resin film according to claim 2 or 3. A fiber-reinforced epoxy resin composite obtained by heating and integrating a laminate of the epoxy resin film according to any one of claims 1 to 4 and a reinforcing fiber assembly. The fiber-reinforced epoxy resin composite material according to claim 5, wherein the solvent content is 0.02% by mass or more and 5% by mass or less.