JP2007297547A - Resin composition for prepreg sheet, prepreg sheet and fiber-reinforced composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for a prepreg sheet having excellent impregnating properties, to provide the prepreg sheet obtained by impregnating fibers with the resin composition for the prepreg sheet and having good fillet-forming properties and to provide a fiber-reinforced composite material prepared by curing the prepreg sheet and improving the strength. <P>SOLUTION: The resin composition for the prepreg sheet comprises a thermosetting resin, a thermoplastic resin, a curing agent and a maleimide polyaddition product represented by formula (1) (wherein, n is an integer of 1-10,000; R<SP>1</SP>and X represent each independently a 1-24C bivalent organic group; and R<SP>2</SP>s represent each independently a 1-24C monovalent organic group). The resin composition provides 10-150 Pa s minimum viscosity during curing and ≤300 Pa s viscosity at 100°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin composition for a prepreg sheet, a prepreg sheet, and a fiber-reinforced composite material. More specifically, a fiber-reinforced composite material having good strength, a self-adhesive prepreg sheet that forms the fiber-reinforced composite material and does not require an adhesive sheet for bonding to a honeycomb core, and a prepreg that can form the prepreg sheet The present invention relates to a resin composition for a sheet.

Epoxy resin compositions are used in fields such as architecture, civil engineering, automobiles, and aircraft as resins having excellent heat resistance.
Fiber reinforced composite materials that use such an epoxy resin composition as a matrix resin have excellent mechanical properties, heat resistance, and water resistance. So far, prepreg sheets using combinations of epoxy resins and reinforcing fibers having various compositions have been proposed. Has been.
Further, in fiber reinforced composite materials such as aircraft structural materials, from the viewpoint of weight reduction of the structural material, it is often formed into a structure in which the plane of the prepreg sheet is joined to the cross section of the honeycomb core having a honeycomb structure, For adhesion between the honeycomb core and the prepreg sheet, a sheet-like adhesive interposed between the honeycomb core and the prepreg is used.

  Therefore, from the viewpoint of shortening the manufacturing process and further weight reduction, the prepreg sheets are laminated on both sides of the honeycomb core without using a sheet-like adhesive, and the prepreg sheet itself is cured and bonded to the honeycomb core at the same time. In addition, so-called self-adhesive cocure molding performed without an adhesive has been required for prepreg sheets, and various resin compositions for prepreg sheets have been proposed (see, for example, Patent Documents 1 to 3). .

In Patent Document 1, “Epoxy resin, aromatic amine curing agent, acid anhydride curing agent, dicyandiamide curing” is used for the purpose of avoiding the generation of porosity (voids and voids generated during resin curing). Complex viscosity measured at 80 ° C. with a vibration frequency of 0.02 Hz, which is an epoxy resin composition comprising one or more curing agents selected from the group consisting of an agent and a novolak curing agent, and a solid rubber and the rate eta _0.02 is 5000 poises or more, the relationship between the complex viscosity eta _0.02 measured in complex viscosity eta ₂ and the vibration frequency 0.02Hz measured at a vibration frequency of 2Hz to logη _0.02 -logη ₂ ≧ 0.5 An "epoxy resin composition characterized by satisfaction" has been proposed. Patent Document 1 describes that polyethersulfone is further added to the epoxy resin composition.

  However, when a conventionally known self-adhesive prepreg sheet is used, the impregnation property of the resin composition for a prepreg sheet into fibers (hereinafter also simply referred to as “impregnation property”) and a fiber reinforced composite material (for example, Since it is difficult to satisfy all fillet-forming properties (hereinafter, also simply referred to as “fillet-forming properties”) at the time of manufacturing a honeycomb core sandwich panel), the strength of the manufactured fiber-reinforced composite material (for example, according to ATSM D1781) In addition, there was a problem that the peel strength when the Climbing Drum Peel test was performed was inferior.

JP-A-5-239317 JP-A-9-194611 JP-A-11-254435

  Accordingly, the present invention provides a resin composition for a prepreg sheet having excellent impregnation properties, a prepreg sheet having good fillet form obtained by impregnating fibers with the resin composition for prepreg sheets, and curing the prepreg sheet. It is an object of the present invention to provide a fiber-reinforced composite material having good strength obtained by the above.

As a result of intensive studies on the above problems, the present inventor has a viscosity of about 50 to 100 ° C., in particular, a low viscosity at 100 ° C. to some extent from the viewpoint of impregnation, and is usually around 120 to 150 ° C. from the viewpoint of fillet formation. It has been found that the observed minimum viscosity during curing needs to be somewhat high.
Based on this new knowledge, a resin composition containing a maleimide polyadduct having a specific structure and having a predetermined viscosity range at a specific temperature is excellent in impregnation, and the fiber is impregnated with the resin composition for a prepreg sheet. The present invention was completed by finding that the prepreg sheet obtained by this process has excellent fillet-forming properties and the fiber-reinforced composite material obtained by curing the prepreg sheet has excellent strength.

That is, the present invention provides the following (1) to (13).
(1) containing a thermosetting resin, a thermoplastic resin, a curing agent, and a maleimide polyaddition product represented by the following formula (1),
A resin composition for a prepreg sheet, having a minimum viscosity during curing of 10 to 150 Pa · s and a viscosity at 100 ° C. of 300 Pa · s or less.

(In the formula, n is an integer of ^{1 to} 10,000, R ¹ and X may each independently have a substituent, and are at least selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom. Represents a divalent organic group having 1 to 24 carbon atoms which may contain one type of heteroatom, and each R ² may independently have a substituent, oxygen atom, nitrogen atom And represents a monovalent organic group having 1 to 24 carbon atoms, which may contain at least one heteroatom selected from the group consisting of sulfur atoms.)

(2) The resin composition for a prepreg sheet according to the above (1), wherein, in X, the divalent organic group is a group represented by the following formula (2).

(In the formula, R ³ and R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, an aromatic group, or an alkyl aromatic group.)

(3) The monovalent organic group is at least one selected from the group consisting of a phenyl group, a cyclohexyl group, an alkyl group having 1 to 6 carbon atoms, and a group represented by the following formula (3). The resin composition for a prepreg sheet according to the above (1) or (2).

(In the formula, R ⁵ may have a substituent and may contain at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom, 1 to 19 carbon atoms It represents a divalent organic group having

(4) The resin composition for a prepreg sheet according to any one of (1) to (3), wherein in R ¹ , the divalent organic group is a group represented by the following formula (4).

(5) The resin composition for a prepreg sheet according to any one of (1) to (4), wherein the thermosetting resin is an epoxy resin and / or a cyanate ester resin.
(6) The resin composition for a prepreg sheet according to any one of (1) to (5), wherein the thermoplastic resin is at least one selected from the group consisting of polyethersulfone, polyetherimide, and polysulfone. .
(7) The resin composition for a prepreg sheet according to any one of (1) to (6), wherein a content of the thermoplastic resin is 30 to 50 parts by mass with respect to 100 parts by mass of the thermosetting resin. .
(8) The resin composition for a prepreg sheet according to any one of (1) to (7), wherein the curing agent contains at least one selected from the group consisting of diaminodiphenylsulfone, organic acid dihydrazide, and dicyandiamide.
(9) The resin composition for a prepreg sheet according to any one of (1) to (8), wherein the content of the curing agent is 25 to 45 parts by mass with respect to 100 parts by mass of the thermosetting resin.
(10) The resin for a prepreg sheet according to any one of the above (1) to (9), wherein the content of the maleimide polyaddition product is 1 to 20 parts by mass with respect to 100 parts by mass of the thermosetting resin. Composition.
(11) A prepreg sheet obtainable by impregnating a fiber with the resin composition for a prepreg sheet according to any one of (1) to (10) above.
(12) The prepreg sheet according to (11), wherein the fiber is at least one selected from the group consisting of carbon fiber, aramid fiber, and glass fiber.
(13) A fiber-reinforced composite material obtainable by curing the prepreg sheet according to (11) or (12).

  According to the present invention, a resin composition for a prepreg sheet having excellent impregnation properties, a prepreg sheet having good fillet form obtained by impregnating fibers with the resin composition for prepreg sheets, and curing the prepreg sheet. Can provide a fiber-reinforced composite material having good strength.

The present invention is described in detail below.
The resin composition for a prepreg sheet of the present invention (hereinafter, also simply referred to as “the composition of the present invention”)
Containing a thermosetting resin, a thermoplastic resin, a curing agent, and a maleimide polyadduct represented by the following formula (1),
The composition has a minimum viscosity during curing of 10 to 150 Pa · s and a viscosity at 100 ° C. of 300 Pa · s or less.

(In the formula, n is an integer of ^{1 to} 10,000, R ¹ and X may each independently have a substituent, and are at least selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom. Represents a divalent organic group having 1 to 24 carbon atoms which may contain one type of heteroatom, and each R ² may independently have a substituent, oxygen atom, nitrogen atom And represents a monovalent organic group having 1 to 24 carbon atoms, which may contain at least one heteroatom selected from the group consisting of sulfur atoms.)

<Thermosetting resin>
The thermosetting resin will be described below.
The thermosetting resin used in the composition of the present invention is not particularly limited as long as it is a synthetic resin that forms a network structure and cures in an insoluble and infusible state when heated. Specific examples thereof include urea resins and melamine resins. , Phenol resin, epoxy resin, unsaturated polyester resin, alkyd resin, urethane resin, and the like. These may be used alone or in combination of two or more.
Of these, epoxy resins, cyanate ester resins, or mixed resins that have excellent mechanical, thermal, and electrical properties, but brittleness often hinders their application expansion. This is preferable because the toughness of the resulting composition of the present invention and, in turn, the strength of the fiber-reinforced composite material of the present invention is further improved.

The epoxy resin is not particularly limited as long as it is a resin composed of a compound having two or more oxirane rings (epoxy groups) in one molecule, and generally has an epoxy equivalent of 90 to 2,000.
A conventionally well-known epoxy resin can be used as such an epoxy resin.
Specifically, for example, epoxy compounds having a bisphenyl group such as bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AF type, biphenyl type, and polyalkylene Bifunctional glycidyl ether type epoxy resins such as glycol type, alkylene glycol type epoxy compounds, epoxy compounds having a naphthalene ring, and epoxy compounds having a fluorene group;
Polyfunctional glycidyl ether type epoxy resins such as phenol novolac type, orthocresol novolak type, trishydroxyphenylmethane type, tetraphenylolethane type;
Glycidyl ester epoxy resins of synthetic fatty acids such as dimer acid;
N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyldiaminodiphenylsulfone (TGDDS), tetraglycidyl-m-xylylenediamine (TGMXDA) represented by the following formula (5), (6) represented by triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, N, N-diglycidylaniline, tetraglycidyl 1,3-bisaminomethylcyclohexane (TG1,3-BAC), tri Glycidylamine epoxy resin such as glycidyl isocyanurate (TGIC);

An epoxy compound having a tricyclo [5.2.1.0 ^2,6 ] decane ring represented by the following formula (7), specifically, for example, cresols or phenols such as dicyclopentadiene and metacresol An epoxy compound which can be obtained by a known production method of reacting epichlorohydrin after polymerization;

（式中、ｍは、０〜１５の整数を示す。）

(In the formula, m represents an integer of 0 to 15.)

Cycloaliphatic epoxy resin; epoxy resin represented by Toray Rethiokol's Flep 10 epoxy resin having a sulfur atom in the main chain; urethane modified epoxy resin having urethane bond; polybutadiene, liquid polyacrylonitrile-butadiene rubber or acrylonitrile butadiene rubber Examples thereof include a rubber-modified epoxy resin containing (NBR).
These may be used alone or in combination of two or more.

In the present invention, the glycidylamine epoxy resin and the bisphenol F type epoxy resin are used in combination, the viscosity of the resulting composition of the present invention, the mechanical properties after curing (for example, elastic modulus, toughness, etc.) and thermal properties. It is preferable because properties (for example, glass transition temperature, coefficient of thermal expansion, etc.) can be easily adjusted, and as a result, the strength of the fiber-reinforced composite material of the present invention can be easily adjusted.
Among the glycidylamine epoxy resins, as tetraglycidyldiaminodiphenylmethane (TGDDM) represented by the above formula (5), for example, ELM-434 (manufactured by Sumitomo Chemical Co., Ltd.), MY-721 (manufactured by Huntsman Advanced Materials) As the triglycidyl-p-aminophenol represented by the above formula (6), for example, MY-0510 (manufactured by Huntsman Advanced Materials), Epicoat 630 (manufactured by Japan Epoxy Resin Co., Ltd.) can be used. ) Etc. can be used.
As the bisphenol F type epoxy resin, for example, commercially available products such as Epicoat 806 and Epicoat 807 (both manufactured by Japan Epoxy Resin Co., Ltd.) can be used.

In the present invention, when another epoxy resin is used in combination with the glycidylamine epoxy resin and the bisphenol F type epoxy resin, an epoxy resin having an aromatic ring in the skeleton is used as the other epoxy resin. It is preferable because it is convenient for optimizing the mechanical properties and thermal properties of the cured product by controlling the form.
Examples of other epoxy resins include bisphenol A type epoxy resin (Epicoat 828, manufactured by Japan Epoxy Resin Co., Ltd.), phenol novolac type epoxy resin (Epicoat 154, manufactured by Japan Epoxy Resin Co., Ltd.), and cresol novolac type epoxy resin (TETRAD-X). Commercial products such as Mitsubishi Gas Chemical Co., Ltd.).

  The cyanate ester resin is not particularly limited as long as it is represented by the following formula (8).

R— (O—C≡N) _n (8)
(In the formula, R represents a divalent or higher valent organic group having an aromatic ring, and n represents an integer of 2 or higher.)

  Specific examples of such cyanate ester resins include 1,3-dicyanate benzene, 1,4-dicyanate benzene, 1,3,5-tricyanate benzene, 1,8- or 2 , 6- or 2,7-dicyanatonaphthalene, 4,4'-dicyanatobiphenyl, bis (4-cyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, bis (3 , 5-dimethyl-4-cyanatophenyl) methane, 2,2-bis (3,5-dimethyl-4-cyanatophenyl) propane, bis (4-cyanatophenyl) sulfone, tris (4-cyanatophenyl) ) Phosphite, 1,1′-bis (4-cyanatophenyl) ethane, 1,3-bis (4-cyanatophenyl-1- (1-methylethylidene)) benzene, 2,2-bis (4- Shi Anatophenyl) hexafluoropropane and the like.

In the present invention, among the various cyanate ester resins exemplified above, 1,1′-bis (4-cyanatophenyl) ethane, 1,3-bis (4-cyanatophenyl-1- (1-methylethylidene) )) It is preferable to use benzene in combination because it is easy to adjust the viscosity and the mechanical and thermal properties after curing of the composition of the present invention to be obtained.
A thermosetting resin can be used individually or in combination of 2 types or more, respectively.

<Thermoplastic resin>
The thermoplastic resin will be described below.
The thermoplastic resin used in the composition of the present invention is not particularly limited as long as it is a synthetic resin that can be molded by heating, and specific examples thereof include polyacetal, polyethylene (PE), polyethylene naphthalate. Phthalate, polyethylene terephthalate, polybutylene terephthalate, polyvinyl chloride (PVC), polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl formal, polysulfone, polyethersulfone (PES), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyphenylene oxide , Polyarylate, polyarylene oxide, polystyrene (PS), polyamide (PA), polyimide (PI), polyetherimide (PEI), polyamideimide (PAI), polycar Sulfonates, polybenzimidazole, include polymethyl methacrylate, and the like, may be used those either alone, or in combination of two or more.
Among these, at least one selected from the group consisting of polyethersulfone, polyetherimide, and polysulfone is preferable because of its high compatibility with the thermosetting resin.

  By containing the thermoplastic resin, the fillet-forming property of the prepreg sheet of the present invention using the obtained composition of the present invention is improved, and the toughness of the composition, and thus the prepreg sheet is used. The strength of the fiber-reinforced composite material of the present invention is improved. This raises the viscosity of the resulting composition of the present invention over a range where the thermosetting resin can be cured (for example, 120 to 150 ° C.), and the tough thermoplastic network is brittle thermosetting. This is considered to reinforce the functional resin.

  In the present invention, the number average molecular weight of the thermoplastic resin is preferably 10,000 to 30,000, and more preferably 15,000 to 25,000. When the number average molecular weight of the thermoplastic resin is within this range, the viscosity range of the obtained composition of the present invention becomes appropriate, and the strength of the fiber-reinforced composite material of the present invention is further improved.

  Moreover, in this invention, it is preferable that it is 30-50 mass parts with respect to 100 mass parts of said thermosetting resins, and, as for content of the said thermoplastic resin, it is more preferable that it is 35-45 mass parts. When the content of the thermoplastic resin is within this range, the impregnation property and fillet-forming property of the resulting composition of the present invention will be better.

<Curing agent>
The curing agent will be described below.
The curing agent used in the composition of the present invention is not particularly limited as long as it can react with a thermosetting resin and / or a thermoplastic resin. For example, aromatic amine compounds having at least one aromatic hydrocarbon group and at least two amino groups in one molecule, dicyandiamide (DICY), and organic acid dihydrazide can be mentioned.

An aromatic amine compound is preferable because the resulting composition of the present invention has excellent heat resistance.
Examples of the aromatic amine compound include diaminodiphenyl sulfone (DDS), diaminodiphenylmethane (DDM), diaminodiphenyl ether (DADPE), bisaniline and benzyldimethylaniline represented by the following formula (9).

Dicyandiamide is a compound represented by H ₂ N—C (═NH) —NH—CN.
The organic acid dihydrazide is a compound having _two groups (—C (═O) —NH—NH ₂ ) obtained by replacing the hydroxy group of the carboxy group with a hydrazino group (—NH—NH ₂ ).
Examples of the organic acid dihydrazide include sebacic acid dihydrazide, adipic acid dihydrazide, succinic acid dihydrazide, malonic acid dihydrazide, and valine dihydrazide.
From the viewpoint of improving the toughness of the resin, addition of dicyandiamide (DICY) and organic acid dihydrazide is preferable.

  Of these, the combined use of diaminodiphenylsulfone and organic acid dihydrazide and / or dicyandiamide improves the fillet-forming property of the prepreg sheet of the present invention using the resulting composition of the present invention, and the composition. It is more preferable for the reason that the toughness of the product, and thus the strength of the fiber-reinforced composite material of the present invention using the prepreg sheet becomes better.

In this invention, it is preferable that it is 25-45 mass parts with respect to 100 mass parts of said thermosetting resins, and, as for content of the said hardening | curing agent, it is more preferable that it is 30-40 mass parts. When the content of the curing agent is within this range, the resulting composition of the present invention has good heat resistance, and the toughness of the composition, and thus the strength of the fiber-reinforced composite material of the present invention is better. Become.
In addition, the content of the curing agent is an equivalent ratio represented by (active hydrogen group of the curing agent) / (functional group in the thermosetting resin that reacts with the active hydrogen group in the curing agent). It is preferably 0.5 to 0.9, and more preferably 0.6 to 0.8.

<Maleimide polyadduct>
The maleimide polyadduct is described below.
The maleimide polyadduct used in the composition of the present invention is a polyadduct represented by the following formula (1).

In the formula, n is an integer of ^{1 to} 10,000, R ¹ and X may each independently have a substituent, and are at least 1 selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom. Represents a divalent organic group having 1 to 24 carbon atoms, which may contain a hetero atom, and each R ² may independently have a substituent, an oxygen atom, a nitrogen atom and A monovalent organic group having 1 to 24 carbon atoms, which may contain at least one heteroatom selected from the group consisting of sulfur atoms.

In Formula (1), n is an integer of 1 to 10,000.
n is preferably an integer of 1 to 5,000, more preferably an integer of 3 to 2,500, and more preferably, n is an integer from the viewpoint of keeping the elastic modulus of the cured resin high. It is an integer of 5 to 1,000.

R ^{1 s} independently have 1 to 24 carbon atoms which may have a substituent and may contain at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom Represents a divalent organic group having
Examples of the divalent organic group having 1 to 24 carbon atoms include an optionally branched chain aliphatic group having 1 to 24 carbon atoms, and a cyclic group having 5 to 18 carbon atoms. Examples thereof include an aliphatic group, an aromatic group having 6 to 18 carbon atoms, an alkyl aromatic group having 7 to 24 carbon atoms, and a heterocyclic group.
The substituent is not particularly limited as long as it does not affect the reaction in producing the maleimide polyadduct. For example, an alkyl group, a cycloalkyl group, and an aryl group can be mentioned.
A hetero atom should just be at least 1 sort (s) chosen from the group which consists of an oxygen atom, a nitrogen atom, and a sulfur atom, and can combine these and can be set as a functional group (for example, sulfonyl group).

Among these, from the viewpoint of facilitating the polyaddition reaction smoothly, a cyclic aliphatic group having 5 to 18 carbon atoms, an aromatic group having 6 to 18 carbon atoms, and 7 to 24 carbon atoms are selected. Preferred are alkyl aromatic groups.
Examples of R ¹ include a group represented by the following formula (4).

X each independently has 1 to 24 carbon atoms which may have a substituent and may contain at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom. It represents a divalent organic group.
The divalent organic group, substituent, and hetero atom as X are as defined above.
Among these, X is a group of 6 to 18 carbon atoms including at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom from the viewpoint of facilitating the polyaddition reaction smoothly. An aromatic group having an alkyl aromatic group having 7 to 24 carbon atoms and a heterocyclic group are preferred.

  Examples of X include a group represented by the following formula (2).

In formula (2), R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group, aromatic group or alkylaromatic group having 1 to 10 carbon atoms.
The alkyl group is not particularly limited as long as it has 1 to 10 carbon atoms, and may be branched.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group.
Examples of the aromatic group include a phenyl group and a naphthyl group.
Examples of the alkyl aromatic group include a tolyl group and a xylyl group.
One preferred embodiment is that R ³ and R ⁴ are n-butyl groups.

R ² may independently have 1 to 24 carbon atoms which may have a substituent and may contain at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom. Represents a monovalent organic group having

Examples of the monovalent organic group having 1 to 24 carbon atoms include an optionally branched chain aliphatic group having 1 to 24 carbon atoms and a cyclic group having 5 to 18 carbon atoms. Examples thereof include an aliphatic group, an aromatic group having 6 to 18 carbon atoms, an alkyl aromatic group having 7 to 24 carbon atoms, and a heterocyclic group.
The substituent is not particularly limited as long as it does not affect the reaction in producing the maleimide polyadduct. For example, an alkyl group, a cycloalkyl group, and an aryl group can be mentioned.

  Among these, from the viewpoint of facilitating the polyaddition reaction smoothly, a cyclic aliphatic group having 5 to 18 carbon atoms, an aromatic group having 6 to 18 carbon atoms, and 7 to 24 carbon atoms are selected. Preferred are alkyl aromatic groups.

  Examples of the monovalent organic group include a phenyl group, a cyclohexyl group, an alkyl group having 1 to 6 carbon atoms, and a group represented by the following formula (3).

In formula (3), R ⁵ may have a substituent and may contain at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom, 1 to 19 Represents a divalent organic group having a carbon atom.

Examples of the divalent organic group represented by R ^{5 in} the formula (3) include an optionally branched chain aliphatic group having 1 to 19 carbon atoms and a cyclic aliphatic group having 5 to 19 carbon atoms. An aromatic group having 6 to 19 carbon atoms, an alkyl aromatic group having 7 to 19 carbon atoms, and a heterocyclic group.
A substituent and a hetero atom are as defined above.

Among these, R ⁵ in formula (3) is a cyclic aliphatic group having 5 to 19 carbon atoms and an aromatic group having 6 to 19 carbon atoms from the viewpoint of facilitating the polyaddition reaction smoothly. Alkyl aromatic groups having 7 to 19 carbon atoms are preferred.
Examples of R ⁵ include a group represented by the following formula (4).

  An alkyl group having 1 to 6 carbon atoms may be branched, and specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group.

  Among these, a monovalent organic group is more excellent in impregnation properties, and more excellent in fillet-forming properties when formed into a prepreg sheet. From the viewpoint of a phenyl group, a cyclohexyl group, an alkyl group having 1 to 6 carbon atoms, and a formula It is preferably at least one selected from the group consisting of groups represented by (3).

In addition, R ² of the maleimide polyadduct represented by the formula (1) is preferably a phenyl group and / or a group represented by the formula (3) from the viewpoint of easy pulverization.
Specifically, one preferred embodiment is that both R ² are phenyl groups.

Examples of the maleimide polyadduct represented by the formula (1) include polyaddition represented by the following formula (10) and the following formula (11).
N in Formula (10) is 10 to 1,000.
N in Formula (11) is 5-500.

The maleimide polyadduct represented by the formula (1) is represented by the formula (10) and / or the formula 11) from the viewpoint that it is excellent in impregnation properties and is excellent in fillet-forming properties when formed into a prepreg sheet Is preferred.
In addition, the maleimide polyadduct represented by the formula (1) is preferably a maleimide polyadduct represented by the formula (11) from the viewpoint of being easily pulverized.
Maleimide polyadducts can be used alone or in combination of two or more.

The maleimide polyadduct is not particularly limited for its production.
For example, when bismaleimide having the same structure is present at both ends, such as a maleimide polyadduct represented by the formula (10), a compound containing two or more thiol groups in one molecule and a bismaleimide compound The method of making it react is mentioned.

  Further, for example, in the case of having an N-hydrocarbon group-substituted maleimide at both ends as in the maleimide polyadduct represented by the formula (11), a compound containing two or more thiol groups in one molecule and bis A maleimide compound is reacted to form a maleimide polyadduct, which is a compound containing two or more thiol groups in one molecule at both ends, and after reaction, an N-hydrocarbon group-substituted maleimide compound is present in one molecule at both ends. And a method of further reacting with a maleimide polyadduct which is a compound containing two or more thiol groups.

  First, a method for obtaining a maleimide polyadduct by reacting a compound containing two or more thiol groups in one molecule with a bismaleimide compound will be described.

  The compound containing a thiol group used in the production of the maleimide polyadduct is not particularly limited as long as it contains two or more thiol groups in one molecule. For example, the divalent organic having 1 to 24 carbon atoms which may have a substituent and may contain at least one hetero atom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom A group in which two thiol groups are bonded to the group.

A divalent organic group, a substituent, and a hetero atom are as defined above.
Among these, from the viewpoint of facilitating the polyaddition reaction smoothly, a cyclic aliphatic group having 5 to 18 carbon atoms, an aromatic group having 6 to 18 carbon atoms, and 7 to 24 carbon atoms are selected. An alkyl aromatic group and a heterocyclic group are preferable.
Examples of the divalent organic group include a group represented by the following formula (2).

In formula (2), R ³ and R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. The alkyl group has the same meaning as described above.

  Examples of the compound containing two or more thiol groups in one molecule include methanedithiol, 1,3-butanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, 1,10-decanedithiol, 1,2-ethanedithiol, 1,6-hexanedithiol, 1,9-nonanedithiol, 1,8-octanedithiol, , 5-pentanedithiol, 1,2-propanedithiol, 1,3-propadithiol, toluene-3,4-dithiol, 3,6-dichloro-1,2-benzenedithiol, 1,5-naphthalenedithiol, 1, 2-benzenedimethanethiol, 1,3-benzenedimethanethiol, 1,4-benzenedimethanethiol 4,4'-thiobisbenzenethiol, 1,3,4-thiadiazole-2,5-dithiol, 1,8-dimercapto-3,6-dioxaoctane, 1,5-dimercapto-3-thiapentane, , 3,5-triazine-2,4,6-trithiol (trimercapto-triazine), 2-di-n-butylamino-4,6-dimercapto-s-triazine, trimethylolpropane tris (β-thiopropio) Nate), trimethylolpropane tris (thioglycolate), polythiol (thiocol, or thiol-modified polymer (resin, rubber, etc.)).

Of these, aromatic thiols containing 2 or more thiol groups in one molecule or heterocyclic thiols are preferred from the viewpoint of superior impregnation and fillet-forming properties, and 2,5-dimercapto- 1,3,4-thiadiazole, 2-di-n-butylamino-4,6-dimercapto-s-triazine, and trimercapto-triazine are more preferable.
Further, from the viewpoint of being easy to handle because it is solid and has no odor, and having a high curing rate, 2,5-dimercapto-1,3,4-thiadiazole, 2-di-n-butylamino-4,6-dimercapto-s- Triazine is preferred.
Compounds containing two or more thiol groups in one molecule can be used alone or in combination of two or more.
X in the formula (1) can be determined by a compound containing two or more thiol groups in one molecule. When X in Formula (1) is an aromatic group or a heterocyclic group, an aromatic thiol or a heterocyclic thiol may be used as a compound containing two or more thiol groups in one molecule.

The bismaleimide compound used when producing the maleimide polyadduct is not particularly limited. For example, the divalent organic having 1 to 24 carbon atoms which may have a substituent and may contain at least one hetero atom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom The thing which has group is mentioned. A divalent organic group is mentioned as one of the preferable aspects that couple | bond with the nitrogen atom of a maleimide structure.
A divalent organic group, a substituent, and a hetero atom are as defined above.

Among these, from the viewpoint of facilitating the polyaddition reaction smoothly, a cyclic aliphatic group having 5 to 18 carbon atoms, an aromatic group having 6 to 18 carbon atoms, and 7 to 24 carbon atoms are selected. Preferred are alkyl aromatic groups.
Examples of the divalent organic group include a group represented by the following formula (4).

  Examples of bismaleimide compounds include 1,2-bismaleimide ethane, 1,6-bismaleimide hexane, N, N′-1,2-phenylene bismaleimide, and N, N′-1,3-phenylene bismaleimide. N, N′-1,4-phenylenebismaleimide, N, N′-1,4-phenylene-2-methyldimaleimide, N, N ′-(1,1′-biphenyl-4,4′-diyl Bismaleimide, N, N '-(3,3'-dimethyl-1,1'-biphenyl-4,4'-diyl) bismaleimide, 4,4'-diphenylmethane bismaleimide, N, N'-(methylenedi) (2-Chloro-4,1-phenylene)) bismaleimide, bis (3-ethyl-5-methyl-4-maleimidophenyl) methane (trade name: BMI-70 (manufactured by KAI Kasei Co., Ltd.) 2,2-bis (4- (4-maleimidophenoxy) phenyl) propane, N, N ′-(sulfonylbis (1,3-phenylene)) dimaleimide, N, N ′-(4,4′-trimethylene Glycol dibenzoate) bismaleimide, maleimide-modified polymer compounds (resin, rubber, etc.).

Of these, 1,6-bismaleimide hexane, 1,2-bismaleimide ethane, and 4,4′-diphenylmethane bismaleimide are preferably used for economic reasons.
The bismaleimide compounds can be used alone or in combination of two or more.

R ¹ in formula (1) can be determined by the structure of the bismaleimide compound. For example, when the bismaleimide compound is 1,6-bismaleimide hexane, R ¹ in formula (1) is a hexylene group, and when it is 4,4′-diphenylmethane bismaleimide, R ¹ is a group represented by the formula (4).

  From the viewpoint that the amount of the bismaleimide compound used is excellent in impregnation and fillet-forming properties, the maleimide group of the bismaleimide compound is contained in 1 mol of the thiol group of the compound containing two or more thiol groups in one molecule. 1.05-1.2 equivalent is preferable, and 1.05-1.15 equivalent is more preferable.

  In this reaction, n is determined by a mixing ratio (molar ratio) between the bismaleimide compound and a compound containing two or more thiol groups in one molecule. For example, when a bismaleimide compound is reacted by adding an equimolar amount to a compound containing two or more thiol groups in one molecule, a polymerization reaction occurs and n> 10, whereas a bismaleimide compound is N is 1 or 2 when a 2-fold mole is added to the compound containing two or more thiol groups in one molecule and reacted. Therefore, a maleimide polyaddition product in which n in the above formula (1) is 0 is obtained by adding a bismaleimide compound to a compound containing two or more thiol groups in one molecule and reacting it. be able to.

  The reaction is preferably carried out in an organic solvent with stirring at room temperature to 150 ° C. for 1 to 24 hours.

The organic solvent used in the reaction may be any one as long as the bismaleimide compound and the compound containing two or more thiol groups in one molecule are both soluble, such as acetone, methyl ethyl ketone, N- Examples thereof include methyl-2-pyrrolidone, tetrahydrofuran, and N, N-dimethylformamide. Among these, methyl ethyl ketone and N, N-dimethylformamide are preferable because of high solubility.
After completion of the reaction, a maleimide polyadduct can be obtained by concentrating and removing the organic solvent under reduced pressure.

Next, production of a maleimide polyadduct having an N-hydrocarbon group-substituted maleimide at both ends, such as a maleimide polyadduct represented by the formula (11), will be described.
As a method for producing such a maleimide polyadduct, for example, first, a compound containing two or more thiol groups in one molecule is reacted with a bismaleimide compound, so that both ends are 2 in one molecule. Maleimide polyaddition, which is a compound containing at least one thiol group, and N-hydrocarbon group-substituted maleimide compound after reaction with maleimide polyaddition which is a compound containing two or more thiol groups in one molecule after reaction The method of making it react further with a thing is mentioned.

  A compound containing two or more thiol groups in one molecule used in the reaction of a compound containing two or more thiol groups in one molecule with a bismaleimide compound is as defined above. It is synonymous with said bismaleimide compound.

  In such a case, the amount of the compound containing two or more thiol groups in one molecule is superior in impregnation and fillet-forming properties, and both ends contain two or more thiol groups in one molecule. From the viewpoint that the thiol group of the compound containing two or more thiol groups in one molecule is 1.05 to 1.2 equivalents per mole of the maleimide group of the bismaleimide compound. Is more preferable, and 1.05-1.15 equivalent is more preferable.

In this way, a maleimide polyaddition which is a compound in which both ends contain two or more thiol groups in one molecule by reacting a compound containing two or more thiol groups in one molecule with a bismaleimide compound. It is a thing.
Then, after this reaction, the N-hydrocarbon group-substituted maleimide compound is further reacted with a maleimide polyadduct which is a compound containing two or more thiol groups in one molecule at both ends, so that N-carbonized at both ends. A maleimide polyadduct having a hydrogen group-substituted maleimide can be obtained.

The N-hydrocarbon group-substituted maleimide compound is not particularly limited as long as it is a compound having a maleimide structure and a hydrocarbon group. For example, N-alkyl group-substituted maleimides such as N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-hexylmaleimide, N-dichlorohexylmaleimide; N such as N-cyclohexylmaleimide -Cycloalkyl group-substituted maleimide; N-aromatic group-substituted maleimide such as N-phenylmaleimide.
Among these, N-phenylmaleimide is preferable from the viewpoint that the maleimide polyadduct is easily pulverized.
Moreover, N-cyclohexylmaleimide and N-phenylmaleimide are preferable in that they can be obtained at low cost.
The N-hydrocarbon group-substituted maleimide compounds can be used alone or in combination of two or more.

  The amount of the N-hydrocarbon group-substituted maleimide compound used is a compound in which both ends contain two or more thiol groups in one molecule from the viewpoint of sealing all ends of the resulting maleimide polyadduct. It is preferable that it is 2-2.5 mol with respect to 1 mol of a certain maleimide polyadduct, and it is more preferable that it is 2-2.1 mol.

The reaction between an N-hydrocarbon group-substituted maleimide compound and a maleimide polyadduct, which is a compound containing two or more thiol groups in one molecule at both ends, is carried out in an organic solvent at room temperature to 150 ° C., 1 to 24. A preferred embodiment is to stir for a period of time.
The organic solvent used in the reaction is as defined above.

In the composition of the present invention, it is preferable to use a maleimide polyaddition product that has been pulverized into fine particles from the viewpoints of excellent impregnation properties and excellent fillet-forming properties of a prepreg sheet.
The method for pulverizing the maleimide polyadduct is not particularly limited. For example, a method using a pulverizer such as a jet pulverizer (manufactured by Seishin Enterprise Co., Ltd.) can be mentioned.
The average particle size after pulverization is preferably 1 to 60 μm, and more preferably 1 to 30 μm, from the viewpoints of better impregnation and better fillet-forming properties of the prepreg sheet.
In the present invention, the average particle size of the pulverized maleimide polyadduct was measured by a laser diffraction / scattering particle size distribution analyzer (manufactured by Seishin Enterprise Co., Ltd.).

  In the composition of the present invention, the content of the maleimide polyaddition product is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the thermosetting resin, from the viewpoint of better impregnation and fillet-forming properties. It is more preferably 1 to 10 parts by mass.

The composition of the present invention contains the above-described thermosetting resin, thermoplastic resin, curing agent and maleimide polyaddition product, and has a minimum viscosity of 10 to 150 Pa · s during curing at 100 ° C. The viscosity is 300 Pa · s or less. As described above, the fillet formability of the prepreg sheet of the present invention using the composition of the present invention is improved by this viscosity range, particularly the lowest viscosity during curing of 10 to 150 Pa · s, at 100 ° C. When the viscosity of the composition is 300 Pa · s or less, the impregnation property of the composition of the present invention is improved.
Here, while the minimum viscosity during curing and the viscosity at 100 ° C. are increased from 25 ° C. to 200 ° C. at a rate of temperature increase of 2 ° C./min, respectively, a viscoelasticity measuring device (DMA) (for example, TA instrument) RDS-II manufactured by the same company) and the complex viscosity at 100 ° C. and the lowest value of the viscosities measured every 30 seconds at a vibration frequency of 10 rad / s.

The composition of the present invention preferably has a fracture toughness value (K _IC ) after curing of 2.00 or more. When the fracture toughness value (K _IC ) is within this range, it can be said that the toughness of the composition of the present invention is sufficiently good, and the strength of the fiber-reinforced composite material of the present invention, in particular, the peeling strength is better. Become.
Here, the fracture toughness value (K _IC ) after curing is measured by a one-side notched three-point bending test according to the method described in ASTM D5045-91 using a resin plate made of a cured product of the resin composition for prepreg. Fracture toughness value (MPa · m ^1/2 ).
Furthermore, the fiber reinforced composite material of the present invention preferably has a peel strength of 25 (lb-in / 3 in) or more. When the peel strength is within this range, it can be suitably used as an industrial product requiring extremely high strength, particularly as an aircraft material.
Here, the peeling strength refers to the strength (lb-in / 3 in) at the time of peeling when a climbing drum peel test according to ATSM D1781 is performed.

  The resin composition for a prepreg sheet of the present invention is an anti-aging agent, an antioxidant, a pigment (dye), a plasticizer, a thixotropic agent, and an ultraviolet absorber as long as the purpose of the present invention is not impaired. Various additives such as an agent, a flame retardant, a solvent, a surfactant (including a leveling agent), a dispersant, a dehydrating agent, an adhesion-imparting agent, and an antistatic agent can be contained.

Specific examples of the anti-aging agent include hindered phenol compounds.
Specific examples of the antioxidant include butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA).

  Specific examples of the plasticizer include dioctyl phthalate (DOP) and dibutyl phthalate (DBP); dioctyl adipate, isodecyl succinate; diethylene glycol dibenzoate, pentaerythritol ester; butyl oleate, methyl acetylricinoleate; phosphorus Examples include tricresyl acid, trioctyl phosphate; propylene glycol adipate polyester, butylene glycol adipate polyester.

Specific examples of the thixotropic agent include Aerosil (manufactured by Nippon Aerosil Co., Ltd.) and Dispalon (manufactured by Enomoto Kasei Co., Ltd.).
Specific examples of the adhesion imparting agent include terpene resins, phenol resins, terpene-phenol resins, rosin resins, and xylene resins.

Specific examples of the flame retardant include chloroalkyl phosphate, dimethylmethylphosphonate, bromine atom and / or phosphorus atom-containing compound, ammonium polyphosphate, neopentyl bromide-polyether, and brominated polyether.
Examples of the antistatic agent include quaternary ammonium salts; hydrophilic compounds such as polyglycols and ethylene oxide derivatives.

  The resin composition for a prepreg sheet of the present invention is not particularly limited with respect to its production. For example, the above-mentioned essential components and optional components may be put in a reaction vessel, and sufficiently kneaded using a stirrer such as a mixing mixer while controlling the temperature under reduced pressure.

  The resin composition for a prepreg sheet of the present invention can be used as a one-component resin composition for a prepreg sheet containing a main component containing a thermosetting resin, a thermoplastic resin and a maleimide polyaddition product, and a curing agent. it can.

Next, the prepreg sheet of the present invention will be described.
The prepreg sheet of the present invention is a prepreg sheet that can be obtained by impregnating fibers with the above-described resin composition for a prepreg sheet of the present invention.

Specific examples of the fiber impregnated with the resin composition for a prepreg sheet of the present invention include, for example, carbon fiber, graphite fiber, aramid fiber, silicon carbide fiber, alumina fiber, boron fiber, high-strength polyethylene fiber, and tungsten carbide fiber. , Reinforcing fibers such as PBO fiber, glass fiber, metal fiber, and the like. These may be used alone or in combination of two or more.
Among these, at least one selected from the group consisting of carbon fiber, aramid fiber and glass fiber is preferable because the impregnation step is simple.

In the present invention, the carbon fiber is not particularly limited, and specific examples thereof include polyacrylonitrile-based carbon fiber (PAN-based carbon fiber), pitch-based carbon fiber, and the like.
Further, the carbon fiber is not particularly limited in its form and arrangement, for example, a unidirectional material in which reinforcing fibers are aligned in one direction, a woven fabric, a non-woven fabric composed of short cut reinforcing fibers, a braid, a tow, a knit, A mat etc. are mentioned. The form and arrangement | sequence of carbon fiber can be freely selected according to the site | part to be used and a use.

  In the present invention, the content of the resin composition for a prepreg sheet impregnated in such fibers is preferably 70 to 35% by volume in the entire volume of the prepreg sheet from the viewpoint of properties such as strength. 60 to 40% by volume is preferable.

The method for producing the prepreg sheet of the present invention is not particularly limited as long as the fiber is impregnated with the resin composition for a prepreg sheet of the present invention.
Examples of the impregnation method include a wet method and a hot melt method.
The impregnation is preferably performed under heating.

  When a prepreg sheet is produced by a wet method, it is preferable to dissolve the resin composition for a prepreg sheet of the present invention in a solvent to prepare a varnish and then impregnate the fiber. Examples of the solvent used when preparing the varnish include ketone solvents such as methyl ethyl ketone (MEK). The amount of the solvent used is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the resin composition for a prepreg sheet of the present invention because the drying process can be shortened.

  When producing a prepreg sheet by the hot melt method, after the resin composition for a prepreg sheet of the present invention is heated and melted, it is uniformly coated on a release paper while uncured to produce a resin film, It is preferable to sandwich the fiber from both sides with a resin film, and then impregnate the resin while applying pressure and heat.

  The heating temperature during the impregnation is preferably 60 to 150 ° C. When heating temperature is 60 degreeC or more, the resin composition for prepreg sheets can fully impregnate carbon fiber, and a prepreg sheet has an appropriate tack | tuck and is excellent in handleability. When the heating temperature is 150 ° C. or lower, the resin curing reaction does not proceed excessively while the carbon fiber is impregnated with the resin composition for prepreg sheet, and the prepreg sheet is excellent in drape.

  Since the prepreg sheet of the present invention uses the composition of the present invention, no sheet-like adhesive is required for bonding to the honeycomb core, and the fillet formability is excellent.

Next, the fiber reinforced composite material of the present invention will be described.
The fiber-reinforced composite material of the present invention is a fiber-reinforced composite material that can be obtained by curing the above-described prepreg sheet of the present invention.

A method for bonding the prepreg and the honeycomb core will be described with reference to the accompanying drawings.
1 and 2 show an example of a fiber-reinforced composite material in which a prepreg sheet and a honeycomb core are bonded.
FIG. 1 is a perspective view schematically showing a fiber reinforced composite material 1.
FIG. 2 is a cross-sectional view schematically showing a cross section of the fiber reinforced composite material 1 cut in parallel with the side surfaces of the prisms of the honeycomb core 11.
In FIG. 2, a part is a fiber reinforced composite material to which a prepreg sheet formed from a conventional prepreg sheet resin composition is bonded, and b part is a prepreg sheet formed from a prepreg resin composition of the present invention. 1 shows a fiber reinforced composite material.
As shown in FIG. 1, the fiber reinforced composite material 1 is obtained by bonding a prepreg sheet 10 and a honeycomb core 11, and the present invention is applied to one or both end faces of the end 12 of the honeycomb core showing a honeycomb structure. The prepreg sheet 10 formed of the above composition is joined, and is heated and cured by an autoclave or the like while being pressed from both ends.

However, even when the prepreg sheet 10 and the honeycomb core 11 are evenly pressed during the heat curing, the resin composition for the prepreg sheet is entirely on the bottom surface as shown in FIG. There is a case where a fillet is not formed on the upper surface portion 13 by falling on the portion 13 ′, or a gap is partially formed on the bonding surface between the prepreg sheet 10 and the honeycomb core 11.
In contrast, as shown in part b of FIG. 2, the resin composition for a prepreg sheet of the present invention is excellent in fillet-forming properties, and thus the prepreg sheet 10 and the honeycomb core 11 are completely bonded. Moreover, an appropriate amount of the resin composition for a prepreg sheet can be present in the prepreg sheet without causing the resin composition for the prepreg sheet to flow out too much from the prepreg sheet and causing the resin component to disappear from the prepreg sheet. Accordingly, curing can be completed while maintaining an appropriate shape of the upper fillet 14. Also, on the lower surface, when the viscosity is once reduced, the lower fillet 14 'is formed by the surface tension, the resin composition for the prepreg sheet is appropriately held, and the curing can be completed.

  The use of the fiber reinforced composite material of the present invention is not particularly limited, but specific examples thereof include motorcycle parts such as motorcycle frames, cowls, and fenders; doors, bonnets, tailgates, side fenders, side panels, fenders, energy absorbing members. Automobile parts such as trunk lid, hard top, side mirror cover, spoiler, diffuser, ski carrier, engine cylinder cover, engine hood, chassis, air spoiler, propeller shaft; top vehicle nose, roof, side panel, door, bogie cover, Side panels for vehicles such as side skirts; railcar parts such as luggage racks and seats; interiors, wing inner panels, outer panels, roofs, floors, etc. Which aero parts; aircraft parts such as window frames, luggage racks, seats, floor panels, wings, propellers, fuselage, etc .; casing use for notebook computers, mobile phones, etc .; medical uses such as X-ray cassettes, top boards; flat speaker panels Applications of acoustic products such as speaker cones; sports equipment applications such as golf heads, faceplates, snowboards, surfboards, protectors; and general industrial applications such as leaf springs, windmill blades, elevators (籠 panels, doors).

When the present inventors used the composition of the present invention as a prepreg sheet, the sulfur bond of the maleimide polyadduct contained in the composition of the present invention caused thermal dissociation at a high temperature (for example, around 100 ° C.). This produces a dissociation product, whereby the composition of the present invention has a viscosity at 100 ° C. of 300 Pa · s or less, and when the obtained prepreg sheet is used as a fiber-reinforced composite material, the dissociation product is a thermosetting resin. It is presumed that the incorporation of the crosslinking accelerates the curing of the thermosetting resin and increases the minimum viscosity.
In addition, said mechanism is the inventors' estimation, and even if a mechanism differs, it is included in the scope of the present invention.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

<Thermosetting resin 1>
As the thermosetting resin 1, triglycidyl-p-aminophenol (MY-0510, manufactured by Huntsman Advanced Materials) represented by the following formula (6) was used.

<Thermosetting resin 2>
As thermosetting resin 2, bisphenol F type epoxy resin (Epicoat 806, manufactured by Japan Epoxy Resin Co., Ltd.) was used.

<Thermoplastic resin 1>
As the thermoplastic resin 1, polyethersulfone (PES) manufactured by Sumitomo Chemical Co., Ltd. was used.

<Curing agent 1>
As the curing agent 1, 3,3′-diaminodiphenylsulfone (3,3′-DDS) manufactured by Wakayama Seika Kogyo Co., Ltd. was used.

<Curing agent 2>
As the curing agent 2, dicyandiamide (Epicure DICY15, manufactured by Japan Epoxy Resin Co., Ltd.) was used.

<Maleimide polyaddition 1>
In 1,500 g of methyl ethyl ketone, 2-di-n-butylamino-4,6-dimercapto-s-triazine (manufactured by Sankyo Kasei Co., Ltd.) and 4,4'-bismaleimide biphenylmethane (manufactured by Kay Kasei Co., Ltd.) And 2-di-n-butylamino-4,6-dimercapto-s-triazine and 4,4'-bismaleimide biphenylmethane in a ratio of 1: 1.1. 272 g (1 mol) of butylamino-4,6-dimercapto-s-triazine and 394 g (1.1 mol) of 4,4′-bismaleimide biphenylmethane were added and reacted at 70 ° C. for 3 hours. After completion of the reaction, methyl ethyl ketone was distilled off under reduced pressure to obtain 650 g (yield 98%) of a maleimide polyadduct represented by the following formula (10). The obtained maleimide polyadduct is designated as maleimide polyadduct 1.

<Maleimide polyadduct 2>
In 1,500 g of methyl ethyl ketone, 2-di-n-butylamino-4,6-dimercapto-s-triazine and 4,4′-bismaleimidobiphenylmethane are mixed with 2-di-n-butylamino-4,6. -313 g of 2-di-n-butylamino-4,6-dimercapto-s-triazine so that the ratio of dimercapto-s-triazine to 4,4'-bismaleimide biphenylmethane is 1.15: 1 1.15 mol) and 358 g (1 mol) of 4,4′-bismaleimidobiphenylmethane (manufactured by Kay Chemical Co., Ltd.) were added and reacted at 70 ° C. for 3 hours. Next, 52 g (0.3 mol) of N-phenylmaleimide was added to the reaction solution and reacted at 70 ° C. for 1 hour. After completion of the reaction, methyl ethyl ketone was distilled off under reduced pressure to obtain 710 g (yield 98%) of a maleimide polyadduct represented by the following formula (11). The obtained maleimide polyadduct is designated as maleimide polyadduct 2.

<Crushing of maleimide polyadduct>
500 g of maleimide polyadduct 1 or maleimide polyadduct 2 was pulverized under conditions of two passes using a jet pulverizer (manufactured by Seishin Enterprise Co., Ltd.).
The particle size of the crushed maleimide polyadduct was measured using a laser diffraction / scattering particle size distribution analyzer (manufactured by Seishin Enterprise Co., Ltd.), and the vertical axis was CDF (cumulative distribution function) based on the measured value. A graph of particle size distribution with the horizontal axis representing the particle size was obtained. Based on this graph, the particle size (D50, unit: μm) when the CDF was 50% and the particle size (D90, unit: μm) when the CDF was 90% were determined.
The evaluation criteria for pulverization workability were ◯ when D50 <30 μm, Δ when D50 <60 μm, and x when D50 <90 μm.
The results are shown in Table 1.

1. Preparation of resin composition for prepreg sheet (Examples 1-2, Comparative Example 1)
Each of the above components was mixed using a stirrer with the composition (parts by mass) shown in Table 1 below to obtain resin compositions for prepreg sheets of Examples 1 and 2 and Comparative Example 1.
The obtained each prepreg sheet resin composition, minimum viscosity during cure, viscosity and fracture toughness at 100 ° C. The (K _IC) were measured by the following methods. The results are shown in Table 1.

(1) Minimum viscosity during curing (abbreviated as “minimum viscosity” in Table 1 below)
While increasing the viscosity of each obtained resin composition for prepreg from 25 ° C. to 200 ° C. at a rate of temperature increase of 2 ° C./min, a viscoelasticity measuring device (DMA) (such as RDS-II manufactured by TA Instruments) It measured using.
The graphs obtained as the measurement results of the viscosities of the compositions of Examples 1 and 2 and Comparative Example 1 are shown in the accompanying drawings.
FIG. 3 is a graph showing the relationship between the viscosity of the compositions of Example 1 and Comparative Example 1 and temperature measured using a viscoelasticity measuring device (DMA).
FIG. 4 is a graph showing the relationship between the viscosity of the compositions of Example 2 and Comparative Example 1 and temperature, measured using a viscoelasticity measuring device (DMA).
Moreover, the value of the minimum viscosity during hardening was calculated | required from the measurement result of the viscosity of the composition of Examples 1, 2 and Comparative Example 1.
Those having a minimum viscosity of 10 Pa · s or more were evaluated as having excellent fillet-forming properties of the prepreg sheet using the prepreg resin composition.

(2) Viscosity at 100 ° C. (abbreviated as “100 ° C. viscosity” in the following Table 1)
The viscosity at 100 ° C. of each obtained prepreg resin composition was measured using a viscoelasticity measuring device (DMA) in the same manner as described above.
Those having a 100 ° C. viscosity of 300 Pa · s or less were evaluated as being excellent in the impregnation property of the resin composition for prepreg into fibers.

(3) Fracture toughness value (K _IC )
Each obtained prepreg resin composition was put into a program oven, heated from 25 ° C. to 180 ° C. at a temperature rising rate of 2 ° C./min under normal pressure, and then cured at 180 ° C. for 2 hours to obtain a thickness of 7 mm. of the resin plate was prepared, the resin plate according to the method described in ASTMD5045-91 used to measure the fracture toughness value (MPa · m ^1/2) by three points with one notched bending test.
A prepreg sheet using a prepreg resin composition having a minimum viscosity of 10 Pa · s or more, a viscosity at 100 ° C. of 300 Pa · s or less, and a fracture toughness value of 2.00 MPa · m ^1/2 or more. It was evaluated that the strength of the cured fiber reinforced composite material was excellent.

2. Preparation of Prepreg Sheet Each prepreg sheet resin composition was applied onto release paper using a reverse roll coater to prepare a resin film. Next, these two resin films were superposed so as to sandwich both surfaces of carbon fibers (Treka (registered trademark) T-700, tensile elastic modulus 230 GPa, manufactured by Toray Industries, Inc.) arranged in one direction in a sheet shape. Thereafter, the resin was impregnated with carbon fiber by heating and pressing to prepare a unidirectional prepreg sheet having a carbon fiber basis weight of 196 ± 5 g / cm ² and a matrix resin mass fraction of 34%.
The impregnation property of each prepreg sheet resin composition into fibers was good. Also from this result, it was confirmed that the resin composition for prepreg having a 100 ° C. viscosity of 300 Pa · s or less has excellent impregnation into fibers.

3. Preparation of Honeycomb Core Sandwich Panel Each prepreg sheet obtained was joined to both cross sections of Nomex honeycomb cores manufactured by Showa Aircraft Co., Ltd., which had a honeycomb pattern, pre-assembled by the vacuum back method, and then heated at an autoclave rate of 2 The honeycomb core sandwich panel was manufactured by raising the temperature to 180 ° C. at a forming pressure of 3 kg / cm ² and then curing at 180 ° C. for 2 hours.
The obtained honeycomb core sandwich panel was cut in parallel with the prisms of the honeycomb core, and the fillets formed on both ends of the honeycomb core were visually confirmed. As a result, the honeycomb core sandwich panel was prepared using the prepreg sheet resin composition prepared in Comparative Example 1. Except for the case of using the prepreg sheet, a fillet of 400 μm or more was formed in all cases, and the fillet forming property was good. Also from this result, it was confirmed that a resin composition for prepreg having a minimum viscosity of 10 Pa · s or more has excellent fillet-forming properties of the prepreg sheet.

Further, the obtained honeycomb core sandwich panel was subjected to a climbing drum peel test according to ATSM D1781, and the peel strength (lb-in / 3 in) was obtained. The results are shown in Table 1 above.
As a result, the honeycomb core sandwich panel using the prepreg sheet prepared using the resin composition for prepreg sheet prepared in Examples 1 and 2 has a peel strength of 25 (lb-in / 3 in) or more, and extremely high strength. Has been found to be suitable for industrial products, particularly aircraft applications. Also from this result, it was confirmed that the strength of the fiber-reinforced composite material of the present invention was excellent.

As is clear from the results shown above, it can be seen that the resin compositions for prepreg sheets prepared in the examples have a 100 ° C. viscosity and a minimum viscosity in a predetermined range and have good impregnation properties and fillet-forming properties.
Conventionally, a composition containing an epoxy resin and polyethersulfone has been proposed.
However, when polyethersulfone is added to the epoxy resin composition, the minimum viscosity during curing of the composition increases, but the viscosity near 100 ° C. also increases, and the impregnation property of the composition into fibers is poor. Occurs.
In contrast, the composition of the present invention has a 100 ° C. viscosity and a minimum viscosity during curing in a predetermined range, and has good impregnation properties and fillet-forming properties.
This will be described with reference to FIG.
FIG. 3 is a graph showing the relationship between the viscosity of the compositions of Example 1 and Comparative Example 1 and the temperature measured using a viscoelasticity measuring device (DMA) as described above.
In FIG. 3, the viscosity at 100 ° C. of Example 1 is close to that of Comparative Example 1. Therefore, it can be said that the composition of Example 1 is almost as easy to impregnate the fiber as Comparative Example 1.
Moreover, the minimum viscosity during hardening of Example 1 is higher than that of Comparative Example 1, whereby the prepreg sheet produced using the composition of Example 1 is excellent in fillet formation.
Thus, the composition of the present invention contains a maleimide polyadduct, whereby the increase in viscosity at 100 ° C. is suppressed, and the lowest viscosity during curing compared to a composition containing no maleimide polyadduct. Can be high.

Moreover, since the composition of this invention also has a favorable fracture toughness value (K _IC ), it can be seen that the toughness is good.
Further, from the results of producing the prepreg sheet and the honeycomb core sandwich panel, it was confirmed that the fillet-forming property of the prepreg sheet and the strength of the honeycomb core sandwich panel were good.

FIG. 1 is a perspective view schematically showing a fiber reinforced composite material including a honeycomb core and a prepreg sheet. FIG. 2 is a cross-sectional view schematically showing a cross section of a fiber-reinforced composite material composed of a honeycomb core and a prepreg sheet. FIG. 3 is a graph showing the relationship between the viscosity of the compositions of Example 1 and Comparative Example 1 and temperature, measured using a viscoelasticity measuring apparatus (DMA). FIG. 4 is a graph showing the relationship between the viscosity of the compositions of Example 2 and Comparative Example 1 and temperature, measured using a viscoelasticity measuring device (DMA).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fiber reinforced composite material 10 Prepreg sheet | seat 11 Honeycomb core 12 End part 13 Upper surface part 13 'Lower surface part 14 Upper fillet 14' Lower fillet a Structure using the prepreg formed with the conventional matrix resin b The composition of this invention is matrix Structure using resin prepreg c Cell size

Claims (13)

Containing a thermosetting resin, a thermoplastic resin, a curing agent, and a maleimide polyadduct represented by the following formula (1),
A resin composition for a prepreg sheet, having a minimum viscosity during curing of 10 to 150 Pa · s and a viscosity at 100 ° C. of 300 Pa · s or less.

(In the formula, n is an integer of ^{1 to} 10,000, R ¹ and X may each independently have a substituent, and are at least selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom. one of the may contain a hetero atom, a divalent organic group having 1 to 24 carbon atoms, R ² are each independently, may have a substituent, an oxygen atom, a nitrogen atom And represents a monovalent organic group having 1 to 24 carbon atoms, which may contain at least one heteroatom selected from the group consisting of sulfur atoms.) The resin composition for a prepreg sheet according to claim 1, wherein in X, the divalent organic group is a group represented by the following formula (2).

(In the formula, R ³ and R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, an aromatic group, or an alkyl aromatic group.) The monovalent organic group is at least one selected from the group consisting of a phenyl group, a cyclohexyl group, an alkyl group having 1 to 6 carbon atoms, and a group represented by the following formula (3). Or the resin composition for prepreg sheets of 2.

(In the formula, R ⁵ may have a substituent and may contain at least one heteroatom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom, 1 to 19 carbon atoms It represents a divalent organic group having The resin composition for a prepreg sheet according to any one of claims 1 to 3, wherein in R ¹ , the divalent organic group is a group represented by the following formula (4).

  The resin composition for a prepreg sheet according to any one of claims 1 to 4, wherein the thermosetting resin is an epoxy resin and / or a cyanate ester resin.   The resin composition for a prepreg sheet according to any one of claims 1 to 5, wherein the thermoplastic resin is at least one selected from the group consisting of polyethersulfone, polyetherimide, and polysulfone.   The resin composition for a prepreg sheet according to any one of claims 1 to 6, wherein a content of the thermoplastic resin is 30 to 50 parts by mass with respect to 100 parts by mass of the thermosetting resin.   The resin composition for a prepreg sheet according to any one of claims 1 to 7, wherein the curing agent contains at least one selected from the group consisting of diaminodiphenylsulfone, organic acid dihydrazide, and dicyandiamide.   The resin composition for a prepreg sheet according to any one of claims 1 to 8, wherein a content of the curing agent is 25 to 45 parts by mass with respect to 100 parts by mass of the thermosetting resin.   The resin composition for a prepreg sheet according to any one of claims 1 to 9, wherein a content of the maleimide polyaddition product is 1 to 20 parts by mass with respect to 100 parts by mass of the thermosetting resin.   A prepreg sheet obtainable by impregnating a fiber with the resin composition for a prepreg sheet according to claim 1.   The prepreg sheet according to claim 11, wherein the fiber is at least one selected from the group consisting of carbon fiber, aramid fiber, and glass fiber.   A fiber-reinforced composite material obtainable by curing the prepreg sheet according to claim 11 or 12.

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