阅读说明：本技术 成型材料、及纤维增强复合材料 (Molding material and fiber-reinforced composite material ) 是由 太田智 市野正洋 寺西拓也 渡边祐介 向坂菜摘 于 2018-05-14 设计创作，主要内容包括：本发明提供可得到相对于模具的脱模性优异、且纤维增强复合材料的表面外观优异、成型后的模具表面的污染少、机械特性及耐热性优异的纤维增强复合材料的成型材料、以及相对于模具的脱模性、表面外观优异、成型后的模具表面的污染少、机械特性及耐热性优异的纤维增强复合材料。本发明的成型材料含有成分(A)：环氧树脂、成分(B)：环氧树脂固化剂、成分(C)：溶解度参数11.2以下且熔点为115℃以下的化合物、以及增强纤维。(The invention provides a molding material which can obtain a fiber-reinforced composite material having excellent releasability from a mold, excellent surface appearance of the fiber-reinforced composite material, less contamination of the mold surface after molding, and excellent mechanical properties and heat resistance, and a fiber-reinforced composite material having excellent releasability from a mold, excellent surface appearance, less contamination of the mold surface after molding, and excellent mechanical properties and heat resistance. The molding material of the present invention contains a component (a): epoxy resin, component (B): an epoxy resin curing agent, component (C): a compound having a solubility parameter of 11.2 or less and a melting point of 115 ℃ or less, and a reinforcing fiber.)

1. A molding material, comprising:

component (A): an epoxy resin;

component (B): an epoxy resin curing agent;

component (C): a compound having a solubility parameter of 11.2 or less and a melting point of 115 ℃ or less; and

and (3) reinforcing fibers.

2. The molding material according to claim 1,

at least one of the compounds contained as the component (C) is a compound selected from the group consisting of an ester compound of a fatty acid and an aliphatic alcohol, an ester compound of a polycarboxylic acid and an aliphatic alcohol, an ester compound of a polyol and a fatty acid, an aliphatic alcohol, a fatty acid amide, and a metal salt of a fatty acid.

3. The molding material according to claim 1 or 2,

at least one of the compounds contained as the component (C) is a compound having a solubility parameter in the range of 8.0 to 9.6 or 10.3 to 10.9.

4. The molding material according to any one of claims 1 to 3,

at least one of the compounds contained as the component (C) is a compound having a melting point of-30 ℃ or higher.

5. A molding material, comprising:

component (A): an epoxy resin;

component (B): an epoxy resin curing agent;

component (C): a compound which is at least one of an ester compound having an alkyl group having 5 to 40 carbon atoms and an aliphatic alcohol having an alkyl group having 5 to 40 carbon atoms; and

and (3) reinforcing fibers.

6. The molding material according to claim 5,

at least one of the compounds contained as the component (C) is an aliphatic compound having a hydroxyl group.

7. The molding material according to claim 6,

at least one of the compounds contained as the component (C) is a sorbitan fatty acid ester.

8. The molding material according to claim 7,

at least one of the compounds contained as the component (C) is sorbitan monostearate.

9. The molding material according to any one of claims 1 to 8, wherein at least one of the epoxy resin curing agents contained as the component (B) is at least one of a polyamine-based compound and an acid anhydride-based compound.

10. The molding material according to any one of claims 1 to 9,

at least one of the epoxy resin curing agents contained as the component (B) is an alicyclic diamine.

11. The molding material according to any one of claims 1 to 10,

at least one of the epoxy resin curing agents contained as the component (B) is dicyandiamide.

12. The molding material according to any one of claims 1 to 11,

the reinforcing fibers are carbon fibers.

13. The molding material according to any one of claims 1 to 12, which is a sheet molding compound.

14. A fiber-reinforced composite material which is a cured product of the molding material according to any one of claims 1 to 13.

Technical Field

The present invention relates to a molding material and a fiber-reinforced composite material.

The present application claims priority based on japanese patent application No. 2017-103062 filed in japan on 24/5/2017, and the contents of which are incorporated herein by reference.

In addition, the present application claims priority based on japanese patent application No. 2017-145253 filed in japan on 27.7.7.2017, and the contents thereof are incorporated herein by reference.

Background

An intermediate material (hereinafter, also referred to as a "molding material") for producing a fiber-reinforced composite material (FRP), particularly a sheet molding compound (hereinafter, also referred to as an "SMC") has been put into practical use in the early 1970 s, and in recent years, there has been an increasing demand for the production of industrial parts, automobile parts, bathtubs, and the like. SMC is composed of reinforcing short fibers and a matrix resin. SMC is produced by impregnating reinforcing short fibers with a thermosetting resin composition and molding the composition into a sheet shape. The fiber-reinforced composite material is mainly produced by heating and compressing SMC in a mold to cure the thermosetting resin composition. Examples of the thermosetting resin used for SMC include unsaturated polyester resin, vinyl ester resin, epoxy resin, and phenol resin.

By using an epoxy resin as the thermosetting resin used for the SMC, high mechanical properties (strength, elastic modulus) and thermal properties (heat resistance) can be exhibited in the fiber-reinforced composite material. In addition, the epoxy resin has high adhesion to other materials, and particularly, the interface adhesion between prepregs using the epoxy resin composition as a matrix resin is very strong. Therefore, when the thermosetting resin is an epoxy resin, a fiber-reinforced composite material in which interfacial failure, which has been a conventional problem, is less likely to occur can be obtained.

As an epoxy resin composition for SMC, the following compositions have been proposed.

(1) An epoxy resin composition which is easily B-staged and comprises an aromatic epoxy resin, an amino compound represented by a specific formula, dicyandiamide and an imidazole compound (patent document 1).

As an epoxy resin composition useful for semiconductor encapsulation, the following compositions have been proposed.

(2) An epoxy resin composition having excellent releasability after continuous molding, which is obtained by blending a melt mixture of a compatibilizing agent such as a surfactant and a release agent such as carnauba wax or stearic acid (hereinafter also referred to as an internal release agent) with an epoxy resin composition containing an epoxy resin, a curing agent and an inorganic filler (patent document 2).

Disclosure of Invention

Problems to be solved by the invention

The fiber-reinforced composite material obtained by curing the SMC can be molded into SMC using a mold having various shapes, and can be continuously produced using the same mold. Therefore, the fiber-reinforced composite material obtained by curing the SMC is required to have excellent releasability from a mold.

However, the epoxy resin composition used for SMC has high adhesion and also strongly adheres to a mold. Therefore, the fiber-reinforced composite material obtained by curing SMC using the epoxy resin composition has poor mold release properties from a mold. The mold-occupied time of the fiber-reinforced composite material having poor releasability becomes long, and productivity is lowered. In addition, if the fiber-reinforced composite material strongly bonded to the mold is to be released from the mold, a load needs to be applied to the fiber-reinforced composite material.

In order to improve releasability of the fiber-reinforced composite material from the mold, an external release agent may be used, but there is a risk that the release agent is transferred to the surface of the fiber-reinforced composite material after release, and the subsequent steps such as coating are adversely affected. In the case of a mold having a complicated shape, a portion where the external mold release agent is difficult to be applied and unevenness in application may occur locally.

In addition, an internal mold release agent may be used in order to improve the mold release property, but the conventional internal mold release agent has the following problems: the eluted internal mold release agent is transferred to a mold to adversely affect the subsequent process, or the eluted internal mold release agent aggregates in the appearance of the fiber-reinforced composite material to affect the appearance.

The epoxy resin composition (1) is said to be easy to B-stage and suitable for SMC. However, the epoxy resin composition of (1) does not take into consideration the releasability of the fiber-reinforced composite material from the mold.

The epoxy resin composition of (2) is said to have excellent releasability after continuous molding in semiconductor encapsulation. (2) The epoxy resin composition of (3) is used in the past, and used as a mold release agent, such as carnauba wax and metal soap. However, when the epoxy resin composition of (2) is used in SMC, the effect as an internal mold release agent cannot be obtained with respect to conventional mold release agents, and the releasability of the fiber-reinforced composite material from a mold is insufficient.

The invention provides a molding material capable of obtaining a fiber-reinforced composite material which has excellent mold release properties with respect to a mold, excellent surface appearance of the fiber-reinforced composite material, less contamination of the mold surface after molding, and excellent mechanical properties and heat resistance, and a fiber-reinforced composite material which has excellent mold release properties with respect to a mold, excellent surface appearance, less contamination of the mold surface after molding, and excellent mechanical properties and heat resistance.

Means for solving the problems

As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by blending a specific compound in a molding material, and have completed the present invention.

The present invention has the following embodiments.

[1]

A molding material, comprising:

component (A): epoxy resin,

Component (B): an epoxy resin curing agent,

Component (C): a compound having a solubility parameter of 11.2 or less and a melting point of 115 ℃ or less, and a reinforcing fiber.

[2]

The molding material according to [1], wherein at least one of the compounds contained as the component (C) is a compound selected from the group consisting of an ester compound of a fatty acid and an aliphatic alcohol, an ester compound of a polycarboxylic acid and an aliphatic alcohol, an ester compound of a polyol and a fatty acid, an aliphatic alcohol, a fatty acid amide, and a metal salt of a fatty acid.

[3]

The molding material according to [1] or [2], wherein at least one of the compounds contained as the component (C) is a compound having a solubility parameter in a range of 8.0 to 9.6 or 10.3 to 10.9.

[4]

The molding material according to any one of [1] to [3], wherein at least one of the compounds contained as the component (C) is a compound having a melting point of-30 ℃ or higher.

[5]

A molding material, comprising:

component (A): epoxy resin,

Component (B): an epoxy resin curing agent,

Component (C): at least one of an ester compound having an alkyl group having 5 to 40 carbon atoms and an aliphatic alcohol having an alkyl group having 5 to 40 carbon atoms, and

and (3) reinforcing fibers.

[6]

The molding material according to [5], wherein at least one of the compounds contained as the component (C) is an aliphatic compound having a hydroxyl group.

[7]

The molding material according to item [6], wherein at least one of the compounds contained as the component (C) is a sorbitan fatty acid ester.

[8]

The molding material according to item [7], wherein at least one of the compounds contained as the component (C) is sorbitan monostearate.

[9]

The molding material according to any one of [1] to [8], wherein at least one of the epoxy resin curing agents contained as the component (B) is at least one of a polyamine-based compound and an acid anhydride-based compound.

[10]

The molding material according to any one of [1] to [9], wherein at least one of the epoxy resin curing agents contained as the component (B) is an alicyclic diamine.

[11]

The molding material according to any one of [1] to [10], wherein at least one of the epoxy resin curing agents contained as the component (B) is dicyandiamide.

[12]

The molding material according to any one of [1] to [11], wherein the reinforcing fiber is a carbon fiber.

[13]

The molding material according to any one of [1] to [12], which is a sheet molding compound.

[14]

A fiber-reinforced composite material which is a cured product of the molding material according to any one of [1] to [13 ].

ADVANTAGEOUS EFFECTS OF INVENTION

According to the molding material of the present invention, a fiber-reinforced composite material having excellent releasability from a mold, excellent surface appearance of the fiber-reinforced composite material, less contamination of the mold surface after molding, and excellent mechanical properties and heat resistance can be obtained.

The fiber-reinforced composite material of the present invention is excellent in mold releasability and surface appearance to a mold, is less contaminated on the mold surface after molding, and is excellent in mechanical properties and heat resistance.

Detailed Description

The following definitions apply to the present description and claims.

The "epoxy resin" is a compound having 1 or more epoxy groups in the molecule. The monofunctional epoxy resin is a compound having 1 epoxy group, the bifunctional epoxy resin is a compound having 2 epoxy groups, the trifunctional epoxy resin is a compound having 3 epoxy groups, and the tetrafunctional epoxy resin is a compound having 4 epoxy groups.

The "solubility parameter" is determined by the method of Fedors, which is one of the methods for determining from the molecular structure. Specifically, the cohesive energy density and the molar volume are determined by using constants described in the following formula (2) and R.F.Fedors, Polymer.Eng.Sci., 14[2],147-154(1974), considering that both depend on the kind and number of substituents.

δ＝[ΣEcoh/ΣV]^1/2 (2)

Wherein δ is a solubility parameter, Σ ecoh is cohesive energy, and Σ V is a molar molecular volume.

The "melting point" is set to the following temperature: in a peak on the lowest temperature side derived from the melting point on a DSC exothermic curve obtained by Differential Scanning Calorimetry (DSC), a temperature corresponding to an intersection of a base line on the endothermic start side and a tangent to the inflection point.

The "β carbon of an amino group" is a carbon atom adjacent to the carbon atom (α carbon) to which the amino group is bonded.

The "curing agent" in the component (B) is an additive which can be cured at an atmospheric temperature of, for example, 100 to 200 ℃ for 2 to 300 minutes. In addition, the component (B) includes those which can function as a "tackifier". The thickener is an additive which can thicken to a desired viscosity value within 1 to 200 hours at an atmospheric temperature of 20 to 80 ℃ and stabilize the viscosity value thereafter.

The "polyamine-based compound" is a compound having 2 or more amino groups in the molecule.

A "reinforcing fiber substrate" is an aggregate of reinforcing fibers. Specific examples of the reinforcing fiber base material include reinforcing fiber bundles, and a sheet-like material in which chopped reinforcing fiber bundles are two-dimensionally and randomly stacked.

"to" indicating a numerical range means: the numerical values recited before and after the above are included as the lower limit value and the upper limit value.

< Molding Material >

A molding material according to an embodiment of the present invention includes an epoxy resin composition containing:

component (A): epoxy resin,

Component (B): an epoxy resin curing agent,

Component (C): a compound having a solubility parameter of 11.2 or less and a melting point of 115 ℃ or less.

In addition, another embodiment of the molding material of the present invention includes an epoxy resin composition containing:

component (A): epoxy resin,

Component (B): an epoxy resin curing agent,

Component (C): the aliphatic alcohol-based organic solvent is at least one of an ester compound having an alkyl group having 5 to 40 carbon atoms and an aliphatic alcohol having an alkyl group having 5 to 40 carbon atoms.

In the present invention, the epoxy resin composition contained in the molding material of the present invention means a component other than the reinforcing fiber contained in the molding material of the present invention.

Examples of the molding material include a prepreg, a tow prepreg, SMC, and BMC. Since the viscosity characteristics of the epoxy resin composition of the present invention and the physical properties of the tackifier are suitable for SMC or BMC, SMC or BMC is preferable as a molding material, and SMC is particularly preferable.

The epoxy resin composition may further contain other components as necessary within a range not impairing the effects of the present invention.

The viscosity of the epoxy resin composition at 25 ℃ is preferably 0.1 to 10 pas, more preferably 0.5 to 5 pas.

The epoxy resin composition has a good impregnation property with respect to the reinforcing fiber base material when the viscosity at 25 ℃ is 0.1 to 10 pas. When the viscosity of the epoxy resin composition is 0.5 to 5 pas at 25 ℃, the coating precision on a carrier film is high (the variation in the weight per unit area is small) in the production of SMC and the like, in addition to the impregnation property with respect to the reinforcing fiber base material.

The viscosity of the epoxy resin composition at 25 ℃ can be measured using an E-type viscometer.

(component (A))

The component (A) is an epoxy resin.

Examples of the component (a) include glycidyl ethers of bisphenols (e.g., bisphenol a, bisphenol F, bisphenol AD, and halogenated products thereof); glycidyl ethers of polyhydric phenols obtained by condensation reaction of phenols with aromatic carbonyl compounds; glycidyl ethers of polyhydric alcohols (polyoxyalkylene bisphenol a and the like); polyglycidyl compounds derived from aromatic amines, and the like.

As the component (a), a bisphenol type epoxy resin which is liquid at 25 ℃ is preferable from the viewpoint of easily adjusting the viscosity of the epoxy resin composition to a viscosity suitable for impregnation into the reinforcing fiber base material and easily adjusting the mechanical properties of the fiber-reinforced composite material to a desired range.

As the bisphenol type epoxy resin, bisphenol a type epoxy resins are more preferable in terms of good heat resistance and chemical resistance of the fiber-reinforced composite material.

Further, bisphenol F type epoxy resins are more preferable because they have a lower viscosity and a higher elastic modulus than bisphenol a type epoxy resins having the same molecular weight.

As the component (a), a bifunctional epoxy resin is generally used.

As the component (a), a trifunctional epoxy resin or a tetrafunctional epoxy resin can be used. By blending a trifunctional epoxy resin and a tetrafunctional epoxy resin, the heat resistance of the fiber-reinforced composite material can be further improved without impairing other physical properties.

Examples of commercially available products of the bifunctional epoxy resin include the following commercially available products:

825, 827, 828EL, 828US, 828XA, 806H, 807, 1750, YL6810, of jER (registered trademark) manufactured by Mitsubishi chemical corporation,

EPICLON (registered trademark) manufactured by DIC corporation 840, 840-S, 850-S, EXA-850CRP, 850-LC, 830-S, 835, EXA-830CRP, EXA-830LVP, EXA-835LV, EX-850 CRP, EX-L-C, EX-C,

YD-127, YD-128G, YD-128S, YD-128CA, YDF-170, and Epotote (registered trademark) manufactured by Nikki-Tekken chemical Co., Ltd,

RE-303S-L, RE-310S, GAN, GOT and the like manufactured by Nippon Kagaku K.K.

As commercially available products of trifunctional or higher epoxy resins, the following are listed:

152, 604, 630LSD of jER (registered trademark) manufactured by Mitsubishi chemical corporation,

YH-434, YH434L, manufactured by Nikkiso chemical Co., Ltd,

SUmiepoxy (registered trademark) ELM434, ELM100, ELM120, manufactured by Sumitomo chemical industries, Ltd,

TETRAD-X manufactured by Mitsubishi gas chemical corporation, and the like.

The component (A) may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The content of the component (A) in the epoxy resin composition of the present invention is preferably designed so that the viscosity of the epoxy resin composition at 25 ℃ is 0.1 to 10 pas, and varies depending on the kind of the component (A).

When a trifunctional or higher epoxy resin is used in combination as the component (a), the content of the trifunctional or higher epoxy resin is preferably 5 to 80 parts by mass in 100 parts by mass of the component (a).

If the amount is within the above range, the heat resistance can be improved while maintaining a viscosity that allows the resin composition to satisfactorily impregnate the reinforcing fibers.

(component (B))

The component (B) is an epoxy resin curing agent.

The component (B) may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The component (B) has an influence on the mechanical properties, storage stability, curing temperature and curing time of a cured product of the molding material of the present invention containing the above-mentioned epoxy resin composition. In addition, the component (B) may function as a thickener.

The component (B) is not limited as long as it is a substance capable of curing an epoxy resin, and examples thereof include: amine compounds, acid anhydride compounds, amine complexes such as phenol, thiol, and lewis acid, boron chloride amine complexes, imidazole compounds, and the like. In addition, the form can be microcapsule type, modified and other forms.

The component (B) preferably contains an amine compound, particularly at least one of a polyamine-based compound and an acid anhydride-based compound described later.

Examples of the amine compound that can be used as the component (B) include polyamine compounds such as aliphatic amines, polyetheramines, alicyclic amines, and aromatic amines, and monofunctional amines.

Examples of the aliphatic amines include ethylenediamine, 1, 3-diaminopropane, 1, 4-diaminobutane, hexamethylenediamine, 2, 5-dimethylhexamethylenediamine, trimethylhexamethylenediamine, diethylenetriamine, iminobispropylamine, bis (hexamethylene) triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N-hydroxyethylethylenediamine, and tetrakis (hydroxyethyl) ethylenediamine.

Examples of the polyetheramines include triethylene glycol diamine, tetraethylene glycol diamine, diethylene glycol bis (propylamine), polyoxypropylene diamine, and polyoxypropylene triamine.

Examples of the alicyclic amines include isophoronediamine, p-menthanediamine, bis (4-amino-3-methyldicyclohexyl) methane, bis (aminomethyl) cyclohexane, 3, 9-bis (3-aminopropyl) -2,4,8, 10-tetraoxaspiro (5,5) undecane, and norbornenediamine.

Examples of the aromatic amines include tetrachloro-p-xylylenediamine, m-xylylenediamine, p-xylylenediamine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 2, 4-diaminoanisole, 2, 4-tolylenediamine, diethyltoluenediamine, 2, 4-diaminodiphenylmethane, 4 ' -diamino-1, 2-diphenylethane, 2, 4-diaminodiphenylsulfone, 4 ' -diaminodiphenylsulfone, m-aminobenzylamine, α - (m-aminophenyl) ethylamine, α - (p-aminophenyl) ethylamine, diaminodiethyldimethyldiphenylmethane, α ' -bis (4-aminophenyl) p-diisopropylbenzene, and the like.

The component (B) may be used alone in 1 kind, or may be used in combination in an arbitrary compounding ratio in 2 or more kinds.

As the component (B), alicyclic amines are preferable in view of their high effect as a thickener.

The component (B) is preferably an alicyclic diamine because the pot life of the molding material containing the epoxy resin composition can be extended and the storage stability of the molding material can be improved by B-staging. Among them, alicyclic diamines having 1 or 2 cyclohexane rings in the molecule are more preferable.

The component (B) is preferably a compound having an alicyclic skeleton in the molecule and an amino group directly bonded to the alicyclic skeleton, from the viewpoint that the pot life of the molding material can be extended and the storage stability of the molding material can be improved by B-staging.

The component (B) is preferably a primary amine having 2 alicyclic skeletons in the molecule, because the pot life of the molding material can be extended and the storage stability of the molding material can be improved by B-staging.

As the component (B), an alicyclic diamine having a substituent other than an amino group on the β carbon of the amino group is preferable. Since the diamine having a substituent other than an amino group on the β carbon of the amino group tends to inhibit the reaction of active hydrogen of the amino group, the pot life of the epoxy resin composition can be further extended.

The substituent other than the amino group is preferably an alkyl group having 1 to 4 carbon atoms, a benzyl group or a cyclohexyl group, more preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group, an ethyl group or an isopropyl group, from the viewpoint of prolonging the pot life of the epoxy resin composition.

As the component (B), a compound represented by the following formula (1) is preferable in view of having the above-described characteristics.

[ chemical formula 1]

Wherein R is¹Is a single bond, methylene, -C (CH)₃)₂-, -O-or-SO₂-，R²、R³、R⁴And R⁵Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

Specific examples of the compound represented by the formula (1) include: 3,3 ' -dimethyl-4, 4 ' -diaminodicyclohexylmethane, 3 ' -diethyl-4, 4 ' -diaminodicyclohexylmethane, bis (4-amino-3-methyl-5-ethylcyclohexyl) methane, 3 ', 5,5 ' -tetramethyl-4, 4 ' -diaminodicyclohexylmethane, and the like.

The compound represented by the formula (1) may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The compound represented by formula (1) is particularly preferably 3,3 '-dimethyl-4, 4' -diaminodicyclohexylmethane from the viewpoint of the rapid curing property of the epoxy resin composition after B-staging.

Further, a monofunctional amine may be blended as the component (B). For example, the thickening properties of the molding material of the present invention can be adjusted by using the alicyclic diamine in combination. The monofunctional amine includes aniline, benzylamine, cyclohexylamine, and the like.

When a monofunctional amine is used in combination as the component (B), the content of the monofunctional amine is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 2 parts by mass, per 100 parts by mass of the component (A), from the viewpoint of avoiding a decrease in pot life of the molding material.

Examples of the imidazole compound include: 2, 4-diamino-6- [2- (2-methyl-1-imidazolyl) ] ethyl-s-triazine, 2, 4-diamino-6- [2- (2 '-methyl-1' -imidazolyl) ] ethyl-s-triazine, 2-phenyl-4, 5-bis (hydroxymethyl) imidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, 2-p-benzoyl-4-methyl-5-hydroxymethylimidazole, 2-m-benzoyl-4, 5-bis (hydroxymethyl) imidazole, imidazole compounds such as 2-p-benzoyl-4, 5-bis (hydroxymethyl) imidazole, in which the hydrogen at the 5-position of 1H-imidazole is substituted with a hydroxymethyl group and the hydrogen at the 2-position is substituted with a phenyl group or a benzoyl group.

Examples of the acid anhydride include cyclic acid anhydrides having a structure in which 1 or more water molecules are removed from 2 or more acids in a molecule.

Examples of the cyclic acid anhydride include dodecenyl succinic anhydride, polyhexamic anhydride, polyazelaic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, phthalic anhydride, pyromellitic anhydride, trimellitic anhydride, and benzophenone tetracarboxylic anhydride.

From the viewpoint of compatibility between pot life and reactivity at the time of curing, the component (B) is preferably a compound which is solid in the epoxy resin at an atmospheric temperature of 25 ℃ and liquid at the time of curing, and among them, dicyandiamide and imidazole are preferable, and dicyandiamide is preferably contained as the component (B). Further, dicyandiamide is preferably used in combination with imidazole which is solid at 25 ℃.

When the component (B) is a solid in the epoxy resin at an atmospheric temperature of 25 ℃, the reactivity with the epoxy resin at 25 ℃ is low and the storage stability is excellent. In particular, the molding material cured with dicyandiamide has high adhesion to the reinforcing fiber. Further, a molding material cured with imidazole has high heat resistance.

The content of the component (B) is preferably 5 to 40 parts by mass, more preferably 7 to 30 parts by mass, based on 100 parts by mass of the component (A).

When the content of the component (B) is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, relative to 100 parts by mass of the component (a), a sufficient curing speed can be obtained. When the content of the component (B) is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, relative to 100 parts by mass of the component (a), the water absorption rate of the fiber-reinforced composite material can be suppressed, and the heat resistance of the fiber-reinforced composite material is less likely to decrease.

When a compound that is solid in an epoxy resin at an atmospheric temperature of 25 ℃ and liquid at the time of curing is used as the component (B), the content thereof is preferably 1 to 20 parts by mass, more preferably 3 to 10 parts by mass, per 100 parts by mass of the component (a).

When the content of the compound is not less than the lower limit of the above range, a sufficient curing rate can be obtained. When the content of the compound is not more than the upper limit of the above range, the water absorption of the fiber-reinforced composite material can be suppressed, and the heat resistance of the fiber-reinforced composite material is less likely to be lowered.

When the component (B) is added as a thickener, phthalic anhydride or hydrogenated phthalic anhydride optionally having a substituent is preferable in addition to the above alicyclic amines in view of its high effect as a thickener.

In addition, in view of the long pot life and the good storage stability of B-stage formation of the molding material containing the epoxy resin composition, in addition to the alicyclic diamine including the alicyclic diamine having 1 or 2 cyclohexane rings in the molecule, tetrahydromethylphthalic anhydride is preferable.

Further, as the molding material of the present invention, in terms of being able to prolong the pot life and being excellent in storage stability of B-stage, in addition to the compound having an alicyclic skeleton in the molecule and having an amino group directly bonded to the alicyclic skeleton, preferable is tetrahydromethylphthalic anhydride.

In particular, as the component (B), in addition to the primary amine having 2 alicyclic skeletons in the molecule, preferable is tetrahydromethylphthalic anhydride from the viewpoint that the pot life of the molding material of the present invention can be extended and the storage stability of B-stage is good.

When the component (B) is added as a thickener in particular, the component having the above-mentioned characteristics is preferable, and specific examples thereof include: the above-mentioned 3,3 '-dimethyl-4, 4' -diaminodicyclohexylmethane, 3 '-diethyl-4, 4' -diaminodicyclohexylmethane, bis (4-amino-3-methyl-5-ethylcyclohexyl) methane, 3 ', 5, 5' -tetramethyl-4, 4 '-diaminodicyclohexylmethane, 4' -diaminodicyclohexylmethane and the like. Further, 3-methyl-1, 2,3, 6-tetrahydrophthalic anhydride or 4-methyl-1, 2,3, 6-tetrahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride or 4-methylhexahydrophthalic anhydride, methyl-3, 6-endomethylene-1, 2,3, 6-tetrahydrophthalic anhydride are exemplified.

These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The content of the component (B) added as a tackifier is preferably such that the active hydrogen is 0.1 to 0.5 equivalent or the acid anhydride is 0.05 to 0.25 equivalent, more preferably 0.20 to 0.45 equivalent or the acid anhydride is 0.10 to 0.23 equivalent, and still more preferably 0.25 to 0.4 equivalent or the acid anhydride is 0.12 to 0.2 equivalent, based on the total amount (molar amount) of epoxy groups contained in the component (a) in the epoxy resin composition.

When the content of the component (B) is not less than the lower limit of the above range, B-staging (thickening) sufficiently proceeds. When the content of the component (B) is not more than the upper limit of the above range, the molding material containing the tackifier of the epoxy resin composition does not become too hard in flexibility and does not excessively decrease in fluidity during compression molding under heating.

(component (C))

The component (C) in the molding material according to one embodiment of the present invention is a compound having a solubility parameter of 11.2 or less and a melting point of 115 ℃ or less. Hereinafter, a compound having a solubility parameter of 11.2 or less and a melting point of 115 ℃ or less, that is, the component (C) in the molding material according to one embodiment of the present invention may be referred to as "embodiment 1 of the component (C)".

In addition, the component (C) in the molding material according to another embodiment of the present invention is at least one compound of an ester compound having an alkyl group having 5 to 40 carbon atoms or an aliphatic alcohol having an alkyl group having 5 to 40 carbon atoms. Hereinafter, the component (C) in the molding material according to another embodiment of the present invention, which is at least one compound of an ester compound having an alkyl group having 5 to 40 carbon atoms or an aliphatic alcohol having an alkyl group having 5 to 40 carbon atoms, may be referred to as "embodiment 2 of the component (C)".

The component (C) in the molding material of the present invention is a component for improving the releasability from a mold of a fiber-reinforced composite material obtained by heating and compression molding the molding material of the present invention, and functions as an internal mold release agent.

When molding a molding material (SMC or the like), an epoxy resin contained in the molding material is cured in a mold. Since epoxy resin has high adhesiveness to metal, a cured product of epoxy resin tends to adhere to a mold. By using the internal mold release agent, the adhesiveness of the interface between the mold and the cured product of the epoxy resin at the time of mold release can be suppressed. Since an epoxy resin has a property of temporarily reaching a low viscosity and flowing until it is cured during the heating compression molding, when an external mold release agent is used to improve the mold release property, there is a risk that the mold release agent flows out of the system due to the influence of the resin flow.

The component (C) is transferred to the interface between the mold and the fiber-reinforced composite material during the heat compression molding, and does not flow out of the system due to the resin flow during the heat compression molding.

The solubility parameter of the component (C) in the embodiment 1 of the component (C) is 11.2 or less. The solubility parameter of the component (C) in embodiment 2 of the component (C) is preferably 11.2 or less. The solubility parameter of the component (C) in embodiment 1 of the component (C) and the solubility parameter of the component (C) in embodiment 2 of the component (C) are preferably 11.0 or less, and more preferably 10.9 or less. Further, it is preferably 8.0 or more, more preferably 8.7 or more, further preferably 8.8 or more, and particularly preferably 8.9 or more.

Specifically, the solubility parameter of the component (C) is preferably 8.0 to 11.2, more preferably 8.7 to 11.2, and still more preferably 8.8 to 11.0. Particularly preferably 8.0 to 9.6 or 10.3 to 10.9, and more preferably 8.9 to 9.6.

When the solubility parameter of the component (C) is within the above range, the rate of separation from the epoxy resin composition during heating compression molding is appropriate, and the fiber-reinforced composite material tends to easily bleed out to the interface between the mold and the fiber-reinforced composite material, and therefore the fiber-reinforced composite material has excellent releasability from the mold.

The melting point of the component (C) in embodiment 1 of the component (C) is 115 ℃ or lower. The melting point of the component (C) in embodiment 2 of the component (C) is preferably 115 ℃. The melting point of the component (C) in embodiment 1 of the component (C) and the melting point of the component (C) in embodiment 2 of the component (C) are preferably-30 ℃ or higher.

The melting point of the component (C) is preferably-20 to 100 ℃, more preferably-10 to 90 ℃, still more preferably-5 to 80 ℃, and particularly preferably 40 to 70 ℃. When the melting point of the component (C) is-30 ℃ or higher, preferably-20 ℃ or higher, more preferably-10 ℃ or higher, further preferably-5 ℃ or higher, and particularly preferably 40 ℃ or higher, the component (C) is less likely to bleed out onto the surface of the molding material before the heating compression molding, the component (C) is less likely to flow accompanying the resin flow at the heating compression molding, the concentration of the component (C) existing at the interface between the mold and the fiber-reinforced composite material can be suppressed from decreasing, and the fiber-reinforced composite material is excellent in releasability from the mold. When the melting point of the component (C) is 115 ℃ or less, preferably 100 ℃ or less, more preferably 90 ℃ or less, further preferably 80 ℃ or less, and particularly preferably 70 ℃ or less, the component (C) moves to the interface between the mold and the molding material before the epoxy resin is cured, and therefore, the fiber-reinforced composite material is excellent in releasability from the mold.

Examples of the component (C) in embodiment 1 of the component (C) include ester compounds of fatty acids and fatty alcohols, ester compounds of polycarboxylic acids and fatty alcohols, ester compounds of polyhydric alcohols and fatty acids, fatty alcohols, fatty acid amides, and metal salts of fatty acids. The aliphatic chain may be a saturated aliphatic chain or an unsaturated aliphatic chain.

Specific examples thereof include: ethylene glycol distearate, stearyl citrate, methyl stearate, myristyl myristate, behenyl alcohol, stearyl alcohol, bisphenol A glycol ether dilaurate, ethylene bis-oleamide, lauramide, sorbitan monostearate, and the like.

The component (C) in embodiment 1 of the component (C) is preferably at least one of an ester compound having an alkyl group having 5 to 40 carbon atoms and an aliphatic alcohol having an alkyl group having 5 to 40 carbon atoms, and the component (C) in embodiment 2 of the component (C) is preferably at least one of an ester compound having an alkyl group having 5 to 40 carbon atoms and an aliphatic alcohol having an alkyl group having 5 to 40 carbon atoms, because alkyl chains are present at a high concentration on the surface of the fiber-reinforced composite material, and thus the releasability from a mold tends to be good.

The component (C) in embodiment 1 of the component (C) and the component (C) in embodiment 2 of the component (C) are preferably ester compounds having an alkyl group having 10 to 30 carbon atoms, and more preferably ester compounds having an alkyl chain having 12 to 20 carbon atoms.

Specifically, the ester compound has a long-chain alkyl group as shown in the following chemical formula.

[ chemical formula 2]

In the above chemical formula, R¹、R²Are each the same or different and are alkyl, R¹And R²At least one of the above groups is an alkyl group having 5 to 40 carbon atoms.

The component (C) is particularly preferably an aliphatic compound having a hydroxyl group, more preferably a sorbitan fatty acid ester, and particularly preferably a sorbitan monostearate represented by the following chemical formula, because the fiber-reinforced composite material has good releasability from a mold and the mold surface tends to be hardly contaminated even when released from the mold.

[ chemical formula 3]

The content of the component (C) is preferably 0.1 to 10 parts by mass, more preferably 0.1 to 7 parts by mass, still more preferably 0.3 to 6 parts by mass, and particularly preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the component (A).

When the content of the component (C) is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and particularly preferably 0.5 part by mass or more per 100 parts by mass of the component (a), the fiber-reinforced composite material is more excellent in releasability from a mold. When the content of the component (C) is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, further preferably 6 parts by mass or less, and particularly preferably 5 parts by mass or less with respect to 100 parts by mass of the component (a), both releasability of the fiber-reinforced composite material from a mold and heat resistance of the fiber-reinforced composite material can be easily achieved.

(other Components)

Examples of other components that may be contained in the epoxy resin composition contained in the molding material of the present invention as needed include a curing accelerator, an inorganic filler, an organic pigment, an inorganic pigment, and the like other than the above-mentioned component (a), component (B), and component (C).

The curing accelerator is preferably used for the following reasons.

By using component (B) in combination with an appropriate curing accelerator, the reaction initiation temperature can be lowered without significantly impairing storage stability, and short-time curing of the molding material can be achieved. In addition, the mechanical properties (bending strength, bending modulus) and the thermal properties (heat resistance) of the fiber-reinforced composite material can be improved.

As the curing accelerator, a urea compound is preferable in terms of increasing the mechanical properties (bending strength, bending elastic modulus) of the fiber-reinforced composite material.

As the urea compound, there can be mentioned: 3-phenyl-1, 1-dimethylurea, 3- (3, 4-dichlorophenyl) -1, 1-dimethylurea, 3- (3-chloro-4-methylphenyl) -1, 1-dimethylurea, 2, 4-bis (3, 3-dimethylureido) toluene, 1' - (4-methyl-1, 3-phenylene) bis (3, 3-dimethylurea), and the like.

Examples of the inorganic filler include: calcium carbonate, aluminum hydroxide, clay, barium sulfate, magnesium oxide, glass powder, hollow glass beads, AEROSIL, and the like.

(method for producing epoxy resin composition)

The epoxy resin composition contained in the molding material of the present invention can be prepared by a conventionally known method. For example, the components may be mixed at the same time to prepare a master batch in which the component (B), the component (C), and the like are dispersed in the component (a) as appropriate, and the master batch may be used to prepare the master batch. When the temperature in the system increases due to heat generation by shearing during kneading, it is preferable to perform an operation of not increasing the temperature during kneading, such as adjusting the kneading speed and water-cooling the kneading kettle.

Examples of the kneading apparatus include: attritor, ultrafine pulverizer, planetary mixer, dissolver, three-roll mill, kneader, universal mixer, homogenizer, homogenizing distributor, ball mill, bead mill. The kneading apparatus may be used in combination of 2 or more.

(use of epoxy resin composition)

The epoxy resin composition contained in the molding material of the present invention is suitable as an intermediate material for producing a fiber-reinforced composite material, i.e., a matrix resin for molding materials, particularly a matrix resin for SMC and a matrix resin for bulk molding compound (hereinafter, also referred to as "BMC").

The epoxy resin composition contained in the molding material of the present invention has a low viscosity and good impregnation properties, and therefore, can be used as a matrix resin composition in a molding material for a fiber-reinforced composite material produced by a resin transfer molding method.

(Effect of epoxy resin composition)

The epoxy resin composition contained in the molding material of the present invention described above, even when containing an epoxy resin having high adhesiveness to a mold, makes it easy to release the fiber-reinforced composite material from the mold, does not impair the surface appearance of the fiber-reinforced composite material, and causes very little mold contamination.

Further, by using the epoxy resin composition, a molding material which is easy to be B-staged, has a long pot life, is excellent in processability and storage stability after B-staging, and is excellent in mechanical properties and heat resistance can be obtained.

(tackifier of epoxy resin composition)

The epoxy resin composition contained in the molding material of the present invention may be a tackifier of the epoxy resin composition. That is, the molding material of the present invention may contain a tackifier of the above epoxy resin composition in place of the above epoxy resin composition.

The tackifier of the epoxy resin composition is a component for thickening, i.e., B-staging, the epoxy resin composition contained in the molding material of the present invention.

The tackifier of the epoxy resin composition can be obtained, for example, as follows.

After the reinforcing fiber base material is impregnated with the epoxy resin composition by a known method suitable for the form of the reinforcing fiber base material, the epoxy resin composition is kept at a temperature of about room temperature to 80 ℃ for several hours to several days, or at a temperature of about 80 to 200 ℃ for several seconds to several minutes, whereby the epoxy group of the component (a) in the epoxy resin composition reacts with the component (B), and the epoxy resin composition is B-staged.

The reaction conditions of the epoxy group of the component (a) and the component (B) are preferably selected so that the viscosity of the tackifier of the epoxy resin composition obtained after the reaction at 23 ℃ falls within the range described below.

The viscosity of the tackifier of the epoxy resin composition at 23 ℃ is preferably 3000 to 150000 pas, more preferably 5000 to 300000 pas.

When the viscosity of the tackifier of the epoxy resin composition at 23 ℃ is not less than the lower limit of the above range, the surface tackiness of the epoxy resin composition is reduced when the molding material is handled. When the viscosity of the tackifier of the epoxy resin composition at 23 ℃ is not more than the upper limit of the above range, the flow characteristics at the time of compression molding under heating become good.

The viscosity of the tackifier of the epoxy resin composition at 23 ℃ was measured using a type B viscometer.

The tackifier for the epoxy resin composition preferably contains the component (a): an epoxy resin; component (B'): a compound having a partial structure represented by the following formula (3); component (B): an epoxy resin curing agent (wherein, the component (B') is excluded); and component (C): a compound having a solubility parameter of 11.2 or less and a melting point of 115 ℃ or less.

In another embodiment, the epoxy resin composition preferably contains, as a tackifier: component (A): an epoxy resin; component (B'): a compound having a partial structure represented by the following formula (3); component (B): an epoxy resin curing agent (wherein, the component (B') is excluded); and component (C): the aliphatic alcohol-based organic solvent is at least one of an ester compound having an alkyl group having 5 to 40 carbon atoms and an aliphatic alcohol having an alkyl group having 5 to 40 carbon atoms.

In another embodiment, the epoxy resin composition preferably contains, as a tackifier: component (a 1): an aromatic epoxy resin; component (a 2): an aliphatic epoxy resin; component (B'): a compound having a partial structure represented by the following formula (3); component (B): an epoxy resin curing agent (excluding the component (B')), and a component (C): a compound having a solubility parameter of 11.2 or less and a melting point of 115 ℃ or less.

In another embodiment, the epoxy resin composition preferably contains, as a tackifier: component (a 1): an aromatic epoxy resin; component (a 2): an aliphatic epoxy resin; component (B'): a compound having a partial structure represented by the following formula (3); component (B): an epoxy resin curing agent (wherein, the component (B') is excluded); and component (C): the aliphatic alcohol-based organic solvent is at least one of an ester compound having an alkyl group having 5 to 40 carbon atoms and an aliphatic alcohol having an alkyl group having 5 to 40 carbon atoms.

[ chemical formula 4]

Wherein R is¹Is a single bond, methylene, -C (CH)₃)₂-, -O-or-SO₂-，R²、R³、R⁴And R⁵Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

The component (a1) in the tackifier of a preferred epoxy resin composition is preferably a liquid aromatic epoxy resin having a viscosity of 0.3Pa · s or more at 25 ℃.

The viscosity of the epoxy resin at 25 ℃ was measured using an E-type viscometer.

(reinforcing fiber)

The reinforcing fiber may be any of various fibers depending on the use and purpose of the molding material, and examples thereof include carbon fibers (including graphite fibers), aramid fibers, silicon carbide fibers, alumina fibers, boron fibers, tungsten carbide fibers, and glass fibers. From the viewpoint of mechanical properties of the fiber-reinforced composite material, carbon fibers and glass fibers are preferable, and carbon fibers are particularly preferable.

The reinforcing fibers are usually used in the form of a reinforcing fiber bundle formed of 1000 or more and 60000 or less single fibers.

The molding material may be present in a state of holding the shape of the reinforcing fiber bundle, or may be present in a bundle divided into a smaller number of fibers. In SMC and BMC, the bundle is generally divided into fewer bundles.

The reinforcing fibers in the SMC and BMC are preferably chopped reinforcing fiber bundles made of short fibers.

The length of the short fiber is preferably 0.3 to 10cm, and more preferably 1 to 5 cm.

When the length of the short fibers is 0.3cm or more, a fiber-reinforced composite material having good mechanical properties can be obtained. When the length of the short fibers is 10cm or less, SMC and BMC having excellent flow characteristics in compression molding under heating can be obtained.

The reinforcing fiber base material in the SMC is more preferably a sheet-like material in which chopped reinforcing fiber bundles are stacked two-dimensionally and randomly.

(SMC)

The SMC as a molding material of the present invention is produced, for example, by sufficiently impregnating the above epoxy resin composition into a sheet of chopped reinforcing fiber bundles and thickening the epoxy resin composition as necessary.

As a method for impregnating the sheet-like product of chopped reinforcing fiber bundles with the epoxy resin composition, various conventionally known methods can be used.

For example, the following methods can be mentioned.

2 sheets of a film uniformly coated with the epoxy resin composition were prepared. The chopped reinforcing fiber bundles were scattered randomly on the coated surface of one film of the epoxy resin composition to prepare a sheet-like article. The coated surface of the epoxy resin composition of the other film was attached to the sheet, and the sheet was impregnated with the epoxy resin composition by pressure-bonding. Then, the epoxy resin composition is thickened to suppress the stickiness of the SMC surface, thereby obtaining an SMC suitable for molding operation.

(BMC)

The BMC of the present invention can be produced by, for example, sufficiently mixing the chopped reinforcing fiber bundles with the above epoxy resin composition to prepare a block, and if necessary, thickening the epoxy resin composition.

As a method for mixing the chopped reinforcing fiber bundles and the epoxy resin composition to form a block, various conventionally known methods can be used, and a method of mixing by a pressure kneader is preferable from the viewpoint of productivity such as impregnation of the chopped reinforcing fiber bundles with the epoxy resin composition and dispersion of the fibers.

The mixing by the pressure kneader may be carried out while heating as necessary. The heating temperature is preferably not higher than the temperature at which the epoxy resin starts to cure, and more preferably 10 to 35 ℃. The pressure at the time of mixing by the pressure kneader does not need to be particularly equal to or higher than the atmospheric pressure, but when the viscosity of the epoxy resin composition is high, if it becomes difficult to knead the epoxy resin composition by introducing air and to impregnate the chopped reinforcing fiber bundles with the epoxy resin composition, the pressure may be equal to or higher than the atmospheric pressure.

After the block is obtained, the epoxy resin composition is thickened, whereby the stickiness of the surface of the BMC can be suppressed, and the BMC suitable for molding operation can be obtained.

(Effect)

The molding material of the present invention described above contains the above-described epoxy resin composition or its tackifier and reinforcing fibers, and therefore, a fiber-reinforced composite material excellent in mold releasability, mechanical properties and heat resistance can be obtained.

< fiber-reinforced composite Material >

The fiber-reinforced composite material of the present invention is a cured product of the molding material of the present invention.

The fiber-reinforced composite material of the present invention can be produced by heat molding a molding material such as SMC or BMC, curing the epoxy resin composition contained in the molding material of the present invention, or further curing a tackifier of the epoxy resin contained in the molding material of the present invention.

Examples of the method for producing a fiber-reinforced composite material using SMC include the following methods.

A material obtained by stacking 1 SMC or a plurality of SMCs is placed between 1 pair of molds. And heating and compressing the SMC at 120-230 ℃ for 2-60 minutes to cure the epoxy resin composition to obtain the fiber reinforced composite material serving as a molded product.

A honeycomb structure such as a cardboard can be used as a core material, and SMC can be disposed on both surfaces or one surface thereof.

Examples of the method for producing a fiber-reinforced composite material using BMC include compression molding, transfer molding, injection molding, and the like.

Since the epoxy resin composition contained in the molding material of the present invention has a high viscosity at around room temperature in many cases, it can be produced in a short time even for a molded article having a complicated shape by a compression molding method in which the epoxy resin composition is cured by pressing BMC into a mold having a predetermined shape or the like and then heating and compressing the BMC.

(Effect)

The fiber-reinforced composite material of the present invention described above is a cured product of the molding material of the present invention, and therefore has excellent mold releasability from a mold, mechanical properties, and heat resistance.

< other embodiment >

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the features described in the claims. Embodiments obtained by appropriately combining the technical means described in the above embodiments in different embodiments are also included in the technical scope of the present invention.