JPH05230232A - Method of manufacturing composite material - Google Patents

Abstract

(57) [Summary] [Purpose] To impart excellent toughness to carbon fiber reinforced polyfunctional maleimide resin composites without impairing the heat resistance, which is a characteristic of the polyfunctional maleimide resin used as a matrix resin. To produce a carbon fiber reinforced polyfunctional maleimide resin composite material capable of being manufactured. [Structure] Carbon fiber is treated with a solution of at least one silane coupling agent selected from aminosilane, epoxysilane, and vinylsilane, and then treated with a low-content treatment solution of epoxy resin, and then a polyfunctional maleimide is used as a main component. A method for producing a composite material, which comprises forming a composite with the resin composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a carbon fiber polyfunctional maleimide composite material having excellent heat resistance and toughness.

[0002]

2. Description of the Related Art Carbon fiber reinforced composite materials have a specific strength
It is widely used for various purposes centering on sports equipment, taking advantage of its excellent specific elasticity. At present, epoxy resins are the mainstream as the matrix resin, but epoxy resins do not have sufficient heat resistance, so carbon fiber reinforced epoxy resin composite materials are increasing in heat resistance, mainly for applications in aerospace products. Can not be fully satisfied. On the other hand, polyimide, which is known as a heat-resistant resin, has excellent heat resistance, but has a problem in terms of molding processability, so that its practical use as a matrix resin has been delayed.

Under these circumstances, polyfunctional maleimide resins, such as bismaleimide resins, which have an excellent balance of heat resistance and moldability, are attracting attention as matrix resins for carbon fiber composite materials. However, polyfunctional maleimide resins have the drawback of poor toughness, which limits their use considerably. As a method of improving this drawback of the polyfunctional maleimide-based resin, a method of blending a rubber component or a thermoplastic resin, a method of copolymerizing other monomers, etc. have been proposed, but the physical properties such as heat resistance are deteriorated. However, there is a problem that the toughness is not sufficiently improved, but the fracture toughness of the resin alone is improved, but the toughness of the carbon fiber composite material is not sufficiently improved. In addition, a method of inserting a kind of adhesive layer called an interleaf or an impact absorbing layer between the layers has been proposed, but there are drawbacks such as the fiber content cannot be increased and the handleability is poor. I haven't arrived.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a carbon fiber reinforced polyfunctional maleimide resin composite material having excellent toughness without impairing heat resistance, which is a characteristic of the polyfunctional maleimide resin used as a matrix resin. It is an object of the present invention to produce a carbon fiber reinforced polyfunctional maleimide-based resin composite material that can be imparted with.

[0005]

Means for Solving the Problems As a result of studies to solve the above-mentioned problems, the present inventors have treated carbon fibers with a specific silane coupling agent solution, treated with an epoxy resin treatment liquid, and then The present invention has been completed by finding that the toughness of the obtained composite material is remarkably improved by forming a composite with a maleimide resin composition.

In the present invention, the carbon fiber is at least one selected from aminosilane, epoxysilane and vinylsilane.
A composite material, which is treated with a solution of one kind of silane coupling agent, and then treated with a low-content treatment solution of an epoxy resin, and then complexed with a resin composition containing polyfunctional maleimide as a main component. Is a manufacturing method.

When carbon fibers are treated with a dilute solution of an aminosilane coupling agent (coupling agent concentration of 2.0% or less) and then with a low-content treatment liquid of a multifunctional epoxy resin, the polyfunctionality is then increased. A resin composition using alkenylphenol as a maleimide and its copolymerization component,
It is preferable to form a composite.

A feature of the present invention is that, when a prepreg and a composite material are composed of a polyfunctional maleimide resin composition as a matrix resin and carbon fibers as a reinforcing material, at least one selected from aminosilane, epoxysilane and vinylsilane as carbon fibers. The point is to use one treated with one kind of silane coupling agent and then treated with a low content treatment solution of epoxy resin. Thus, it is possible to impart significantly improved toughness to the carbon fiber composite material formed by molding the prepreg obtained by treating with a specific silane coupling agent and then treating with an epoxy resin. If used as it is, the toughness as a composite material is not sufficiently exhibited even when it is combined with a resin composition having high toughness.

In the present invention, the term "carbon fiber" means both carbon fiber and graphite fiber. This carbon fiber is obtained by carbonizing a fibrous material such as polyacrylonitrile or pitch, which is usually referred to as "precursor", or by heating it to a graphite temperature. Above all, the tensile strength is 4500 MPa or more and the elongation is 1. A carbon fiber having a high strength and a high elongation of 7% or more is preferably used. Further, it is suitable to introduce functional groups such as hydroxyl groups and carboxylic acid groups on the surface by electrolytically oxidizing or ozone oxidizing the surface of the carbon fiber.

The silane coupling agent used in the present invention is as follows. Aminosilane is γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyl-methyl-diethoxysilane,
γ-ureidopropyltriethoxysilane, γ- (2-
Aminoethyl) aminopropyltrimethoxysilane and the like, and the epoxysilane is γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and the like, and the vinylsilane includes vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriacetoxysilane and the like.
A compound in which the functional group is an amino group is particularly preferable. A partial condensate of these silane coupling agents can also be used.

As the method for treating the carbon fiber with the silane coupling agent, any treatment method which is usually used may be used, but a method of treating the carbon fiber by passing it through a low concentration solution of the silane coupling agent is particularly preferable. In this case, when the concentration of the silane coupling agent in the solution is high, the focusing of the carbon fibers becomes too strong, and it becomes difficult to obtain a uniform composite material,
It is important to use a low concentration solution because the toughness of the composite material will decrease. The solution concentration is preferably 2.0% by weight or less, particularly preferably 0.001 to 2.0% by weight.

As the solvent for preparing the low-concentration solution of the silane coupling agent, any solvent can be used as long as it dissolves the silane coupling agent and is substantially inert to the silane coupling agent. Good, but considering the drying step after the treatment, a high boiling point organic solvent is not preferable. As a solvent when an aminosilane coupling agent is used as the silane coupling agent, a lower alcohol such as ethyl alcohol, a mixed solvent of a lower alcohol and water, a water / alcohol mixed solvent containing an acid component such as acetic acid, and the like are particularly preferable. ..

The carbon fibers treated with these silane coupling agent solutions are used after removing volatile components such as solvents by air drying and / or heat treatment. The epoxy resin used in the present invention may be a known epoxy resin,
For example, the resins listed below.

Polyglycidyl ethers of diphenylolalkanes such as diphenylolpropane, diphenylolethane and diphenylolmethane; polyglycidyl ethers of polyhydric phenols such as novolac, cresol and resole; cyclohexane, cyclopentadiene, dicyclo Epoxy compounds produced by epoxidation of alicyclic compounds such as pentadiene, for example 3,4-epoxy-6-
(3,4-Epoxy-6-methyl-cyclohexane) -methyl ester of methyl-cyclohexane-carboxylic acid; poly (epoxyalkyl) ether of aliphatic polyoxy compound such as ethylene glycol and glycerin; aromatic or aliphatic carboxylic acid Examples thereof include epoxyalkyl esters of carboxylic acids such as glycidyl ester. Further, for example, U.S. Pat. No. 3390037 and 29
It may be a pre-reactant of an epoxy compound and a curing agent as described in 70983 and 3067170, or may be a simple mixture.

These epoxy compounds may be used alone or in combination of two or more. Suitable epoxy resins include, for example, diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, tetraglycidyl derivative of diaminodiphenylmethane, triglycidyl derivative of aminophenol, triglycidyl derivative of tris (hydroxyphenyl) methane, glycidyl dihydroxynaphthalene. Examples thereof include ether and diglycidyl ether of bis (hydroxyphenyl) fluorene.

As the method for treating the carbon fiber treated with the silane coupling agent with the treatment liquid containing a low amount of epoxy resin, a method of passing through the treatment liquid containing a low amount of the epoxy resin is preferable. If the epoxy resin content in the treatment liquid is too high, the amount of adhesion on the carbon fiber will be too large and the subsequent handling will not only be reduced, but it will also be composited with a resin composition containing polyfunctional maleimide as the main component and molded. However, it is important to use a low-content treatment liquid because it lowers the heat resistance. The epoxy resin content of the treatment liquid is 10% by weight or less, preferably 0.01 to 5.0% by weight.

The solvent used for the low content treating solution of the epoxy resin used in the present invention is a solvent in which the epoxy resin is dissolved or partially dissolved or uniformly dispersed and suspended, and is substantially inert to the epoxy resin and Any solvent may be used as long as it does not adversely affect the carbon fiber treated with the silane coupling agent, but a high boiling point organic solvent is not preferable in consideration of the drying step after the treatment. Usually, lower alcohols such as acetone, methyl ethyl ketone, methylene chloride and ethanol are preferably used. Carbon fibers treated with these epoxy resin treatment liquids are subjected to air-drying and / or heat treatment to remove volatile components such as a solvent, or after partially reacting the epoxy resin adhered to the carbon fibers, a polyfunctional maleimide. Is compounded with a resin composition containing as a main component.

The polyfunctional maleimide-based resin composition used in the present invention contains 30% by weight or more, preferably 40% or more, of a compound having two or more maleimide groups in the molecule.
It is a resin composition that accounts for at least wt%. A monofunctional maleimide compound or another copolymerizable reactive compound may be contained within a range that does not deteriorate physical properties such as heat resistance and toughness.

As the polyfunctional maleimide, 1,2-bismaleimideethane, 1,6-bismaleimidohexane, 1,12-bismaleimidododecane, 1,6-bismaleimide- (2,2,4-trimethyl) Hexane,
1,6-Bismaleimide- (2,4,4-trimethyl)
Hexane, 1,3- or 1,4-bismaleimidobenzene, 4,4'- or 3,3'-bismaleimidodiphenylmethane, 2,4-, 2,6- or 3,4-bismaleimidotoluene, 3, 3'- or 4,4'-bismaleimide diphenyl sulfone, 4,4'- or 3,4'-bismaleimide diphenyl ether, 4,4-bismaleimide dicyclohexylmethane, 4,4'-bismaleimide dicyclohexane, 4, 4'-bismaleimide diphenylcyclohexane, 4,4'-bismaleimide diphenyl sulfide, N, N'-m- or p-xylylene bismaleimide, N, N'-m-phenylene bis-citracone imide, N, N '-4,4'-Diphenylene bis-citraconic imide, 2,2-bis [4- (4-maleimidophenoxy) phen Le] propane, bis [4- (4-maleimide phenoxy) phenyl] sulfone, bis [4-
(3-maleimidophenoxy) phenyl] sulfone,
1,3-bis (4-maleimidophenoxy) benzene,
1,3-bis (3-maleimidophenoxy) benzene,
Examples thereof include N, N '-[1,3-phenylene-di- (2,2propyriten) -di-p-phenylene] bismaleimide, and a mixture thereof and a prepolymer composed of maleimide and diamine can also be used. As the diamine used, aromatic diamine such as diaminodiphenylmethane is preferable. 4,4'-bismaleimide diphenylmethane, this compound and 1,6-bismaleimide (2,2,4
A eutectic mixture of -trimethyl) hexane and bismaleimidotoluene is particularly preferred.

As the reactive compound copolymerizable with the polyfunctional maleimide compound, for example, o, o'-diallylbisphenol A, o, o'-diallylbisphenol F,
Triallyl isocyanurate, divinylbenzene, N-
Examples thereof include vinylpyrrolidone and ethylene glycol dimethacrylate. These copolymerizable reactive compounds are used alone or in a mixture of 70% by weight or less in the resin composition,
It is preferably used in the range of 50% by weight or less. Among these copolymerizable reactive compounds, o, o'-diallylbisphenyl A and o, o'-diallylbisphenyl F
Alkenylphenols such as alkenylphenols, pre-reacted products of these alkenylphenols with usual epoxy resins, and mixtures thereof are also effective for improving the toughness and processability of the resin composition. It is preferably used in the range.

The resin composition containing a polyfunctional maleimide as a main component can be easily cured by heat, but a catalyst is added for the purpose of imparting desired characteristics to the cured product or adjusting the curing characteristics. You may. As the catalyst, an organophosphine, an organophosphonium salt or a complex thereof, an ionic catalyst such as an imidazole, a tertiary amine, a quaternary ammonium salt, and a boron trifluoride amine salt, and an organic peroxide, azobisisobutyrate. A radical polymerization catalyst such as ronitrile can be used. The amount of the catalyst added may be determined according to the purpose, but from the viewpoint of the stability of the resin composition, it is preferably 0.01 to 5% by weight with respect to all the resin components.

Further, reactive elastomers such as carboxyl group terminated butadiene-acrylonitrile copolymer, carboxyl group terminated polybutadiene, acryloyloxy group terminated butadiene-acrylonitrile copolymer, epoxy resin, unsaturated polyester resin, phenol resin, silicone resin, triazine. Thermosetting resins such as resins, and thermoplastic resins such as polyether sulfone, polyether imide, polyether ketone, thermoplastic polyimide, polyester, polyamide, polyamide imide may be added. Particularly, the epoxy resin is preferable in order to improve the handleability of the resin and the compatibility with the carbon fiber, and the addition amount thereof is preferably 30% or less. If it is used in an amount of more than 30% by weight, the viscosity of the system becomes too high, which not only causes impregnation failure during prepreg formation but also causes deterioration of tack characteristics and drape characteristics of the prepreg. It is also possible to add and mix a small amount of fine inorganic particles such as finely divided silica.

In carrying out the present invention, first, the carbon fiber is treated with the above-mentioned silane coupling agent solution, and then with the low epoxy resin content treating solution. As a treatment method, a dipping method is preferable. Then, the treated carbon fiber is compounded with a resin composition to obtain a target composite material.

The ratio of the treated carbon fiber to the resin composition containing polyfunctional maleimide as a main component can be appropriately set depending on the purpose, but the treated carbon fiber / polyfunctional maleimide is mainly used in a weight ratio. Resin composition as component = 50
The range of / 50 to 75/25 is preferable.

The composite material comprising the treated carbon fiber and the resin composition containing polyfunctional maleimide as a main component can be produced by a known method. For example, first, a resin composition is formed into a film by a hot melt method or a solvent method, and then a pre-containing material (so-called prepreg) of a carbon fiber and a resin composition is manufactured by a heat impregnation method, which is vacuum bag / autoclave. The method of hardening by the method can be used.

[0026]

The present invention will be described in more detail with reference to the following examples. (Examples 1 and 2) As a silane coupling agent treatment solution, γ-aminopropyltriethoxysilane was mixed with a water / ethanol (water / ethanol = 1/9 weight ratio) mixed solvent to prepare a 0.05 weight% solution. It was adjusted. High strength medium elasticity carbon fiber (MR-50K, manufactured by Mitsubishi Rayon Co., Ltd.)
A tensile strength of 5600 MPa and an elastic modulus of 300 GPa) were soaked and passed. It was dried with hot air at 120 ° C. for 2 minutes, air-dried, and then wound. Next, a solution of triglycidyl ether of tris (hydroxyphenyl) methane (Tactix 742, manufactured by Dow Co., Ltd.) in an amount of 1.0% by weight of methyl ethyl ketone was prepared as a low epoxy resin-containing treatment liquid, and the silane coupling-treated carbon fiber was further immersed therein. , Pass, 120
It was dried with hot air for 2 minutes at 0 ° C., air-dried and wound up. 80 ° C
And dried under reduced pressure of 15 mmHg for 12 hours. Upon treatment, the carbon fiber had a weight gain of 2.0% by weight. Next, a unidirectional prepreg was manufactured by the hot melt method from the resin composition shown in Table 1 and the carbon fiber treated as described above. Carbon fiber basis weight of prepreg 145g / m2
The resin content was 36% by weight. As for [impact resistance], this prepreg is cut into small pieces of a predetermined size and laminated on (+ 45/0 / -45 / 90) 4S,
Autoclave molding (6 hours at 180 ℃, 6kg / cm2)
Then, post-curing (232 ° C. for 6 hours) was performed to prepare a test piece for compressive strength test after impact damage. Using this test piece, SACMA (Suppliers of Advanced Compo
sites Materia Is Asociation) Recommended Method S
The compressive strength after impact of 1500 in-1b / in was measured according to RM2-88. [Heat resistance] is determined by laminating this prepreg in a 0 ° 16 layer, molding under the above-mentioned molding conditions, and measuring the interlaminar shear strength (ILSS) at 177 ° C. and 232 ° C. according to ASTM D-2344. did. The evaluation results are shown in Table 1.

[Table 1]

(Comparative Example 1) A composite material was obtained in the same manner as in Example 1 except that carbon fibers not treated with aminosilane or epoxy resin were used. The evaluation results are shown in Table 1.

(Example 3) As a treatment liquid containing a low amount of epoxy resin, a 1.5 wt% acetone solution of tetraglycidyldiaminodiphenylmethane (YH434L manufactured by Tohto Kasei Co., Ltd.) was used, and the weight increase of carbon fiber was 2.5 wt%. A composite material was obtained in the same manner as in Example 1 except that The evaluation results are shown in Table 1.

Example 4 γ-ureidopropyltriethoxysilane was dissolved in a water-ethanol (0.5 / 9.5 weight ratio) mixed solvent, and a 0.05 weight% solution was treated with a silane coupling agent. Example 1 except that it is used as
A composite material was obtained in the same manner as in. The evaluation results are shown in Table 1.

(Example 5) 3-glycidoxypropyl-
Trimethoxysilane in water-ethanol (1/9 weight ratio)
Was mixed with a solvent containing a small amount of acetic acid, and a 1.0 wt% solution was used as a silane coupling agent treatment solution.
A composite material was obtained in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 6 Vinyltriethoxysilane was dissolved in a solvent prepared by adding a small amount of acetic acid to water-acetone (1/50 weight ratio) and a 0.2% by weight solution was used as a silane coupling agent treatment solution. A composite material was obtained in the same manner as in Example 1. The evaluation results are shown in Table 1. From these results, it is known that the composite material obtained by the method of the present invention has excellent heat resistance and impact resistance.

[0032]

The composite material obtained by the method of the present invention has excellent heat resistance, impact resistance and mechanical properties, and is useful as a molding material, especially as a heat resistant material for aerospace.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nao Tada 4-60, Sunadabashi, Higashi-ku, Nagoya, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Laboratory

Claims (2)

[Claims] 1. A carbon fiber is treated with a solution of at least one silane coupling agent selected from aminosilane, epoxysilane and vinylsilane, and then treated with a low content treatment solution of an epoxy resin, and then a polyfunctional maleimide is added thereto. A method for producing a composite material, which comprises compounding with a resin composition as a main component. 2. A carbon fiber is treated with a dilute solution of an aminosilane coupling agent (coupling agent concentration of 2.0% or less), and then treated with a low-concentration treatment solution of a polyfunctional epoxy resin to obtain a polyfunctionality. A method for producing a composite material, which comprises forming a composite with a resin composition containing maleimide and alkenylphenol as main components.