JPH0437857B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention provides a heat-resistant fiber-reinforced composite material in which a matrix is a cured product of an epoxy resin composition containing two specific types of polyglycidyl derivatives and an epoxy curing agent as essential components, and fibers are used as a reinforcing material. It is related to. [Prior Art] Fiber-reinforced composite materials using a cured product of an epoxy resin composition as a matrix and reinforcing materials such as carbon fibers, alumina fibers, and polyamide fibers have excellent mechanical properties, and are therefore used in various ways. It is used in structural parts, sports and leisure products, etc. in many industries. [Problems to be solved by the invention] However, as the field of application of composite materials has expanded in recent years, chemical stability and mechanical There is a growing demand for materials that maintain their physical properties. In fiber-reinforced composite materials, the resin used as a matrix is important in order to maximize the characteristics of the reinforcing fibers.Therefore, various epoxy resin compositions are being actively developed. For example, in Japanese Patent Publication No. 55-25217, an epoxy resin consisting of N,N,N',N'-tetraglycidyldiaminodiphenylmethane and diphenyldiaminosulfone is used as a matrix. Carbon fiber reinforced composite materials have been proposed. Although this composite material has high interlaminar shear strength and heat resistance, the cured product has low elongation, making it hard and brittle.
In addition, it is susceptible to thermal shock, so it is not necessarily satisfactory for use in special applications such as aircraft.
Furthermore, a mixture of N,N,N',N'-tetraglycidyldiaminodiphenylmethane and diphenyldiaminosulfone exhibits a viscosity of 500 poise or more at 50 DEG C., making it difficult to handle. Furthermore, since this mixture has poor reactivity, it is necessary to carry out after-cure at a high temperature of 180° C. or higher for 4 hours or more in order to sufficiently carry out the curing reaction. In order to improve these drawbacks, when a boron trifluoride monoethylamine complex salt or a boron trifluoride piperazine complex salt is used as a curing accelerator in the composition, the reactivity is improved, but heat resistance etc. are impaired, and on the other hand, the flexibility Addition of a reactive elastomer may be considered as an improvement, but it was found that the heat resistance and bending strength were significantly reduced. An object of the present invention is to provide a fiber-reinforced composite material that has high interlaminar shear strength, heat resistance, and improved flexibility. [Means for Solving the Problems] The present invention provides: (A) N,N,N',N'-tetraglycidylbis(aminophenyl)methane and/or its condensation product; (B) at least one aromatic ring; A polyglycidyl derivative of an aminophenol compound substituted with alkyl groups and/or a condensate thereof, and (C) a cured product of an epoxy resin composition containing an epoxy curing agent as an essential component were used as a matrix, and fibers were used as a reinforcing material. A heat-resistant fiber-reinforced composite material is provided. As a result of intensive studies in view of the above-mentioned circumstances, the present invention has been developed based on (A)
N,N,N',N'-tetraglycidylbis(aminophenyl)methane and/or its condensation product and (B) a polyglycidyl derivative of an aminophenol compound having at least one alkyl group substituted on the aromatic ring and/or It has been discovered that when an epoxy resin composition containing the condensate is used, a fiber-reinforced composite material with high interlaminar shear strength, high heat resistance, and improved flexibility can be obtained. Further, since the above composition has high reactivity and low viscosity, it has good workability in producing composite materials. The present invention will be explained in detail below. (A)N, N, N′ used in the present invention,
N'-tetraglycidyl bis(aminophenyl)
Sumiepoxy ELM-434, which is generally commercially available as methane and/or its condensation product
(manufactured by Sumitomo Chemical Co., Ltd.), Araldite MY-720,
MY9512 (manufactured by Ciba Geigy) etc. are used. Further, one of the polyglycidyl derivatives is a polyglycidyl derivative of aminophenol having one or more alkyl groups attached to an aromatic ring and/or a condensate thereof. Preferably at 25°C, especially from the viewpoint of moldability.
It is a polyglycidyl derivative with a viscosity of 15 poise or less. The method for producing this polyglycidyl derivative is not particularly limited, but to give an example, an alkyl group-substituted aminophenol is mixed in an excess (for example, 5 times the mole, preferably 10 times or more by mole) of epihalohydrin (for example, epichlorohydrin) at a temperature below 100°C. After the addition reaction of epihalohydrin to the amino group at a temperature of 40 to 100°C, an aqueous solution of caustic alkali is added dropwise under reduced pressure, and at the same time water in the reaction system is distilled off azeotropically to carry out an epoxidation reaction. There are several methods. The above reaction is characterized in that side reactions other than the epoxidation reaction are extremely suppressed, unlike existing epoxidation reactions. Therefore, a low molecular weight polyglycidyl derivative with a high content of epoxy groups can be obtained. Particularly preferably, epihalohydrin is used in an amount of about 15 moles or more.
A polyglycidyl derivative having a viscosity of 15 poise or less at .degree. C. is obtained. This is an extremely low value for a trifunctional polyglycidyl derivative. The polyglycidyl derivative used in the present invention is
Approximately three polyglycidyl groups are bonded to one aromatic ring, and the epoxy group content is higher than that of existing polyglycidyl derivatives, so the cured product has a high crosslinking density and has a high degree of heat resistance. It is thought that sexual expression occurs. The alkyl group of the alkyl group-substituted aminophenol compound which is a raw material for the polyglycidyl derivative used in the present invention has 1 to 5 carbon atoms, preferably one having one alkyl group substitution, and specifically 4 carbon atoms.
-amino-m-cresol, 4-amino-o-cresol, 6-amino-m-cresol, 5-amino-m-cresol, 3-ethyl-4-aminophenol, 2-ethyl-4-aminophenol, etc. Preferable examples include one or more types.
Particularly preferred are 4-amino-m-cresol, 4-
Amino-o-cresol. The amount of (B) the polyglycidyl derivative of an aminophenol compound substituted with at least one alkyl group on the aromatic ring and/or its condensate used in the present invention is (A) N, N, N', N'- The amount is usually 10 to 50% by weight, preferably 10 to 30% by weight, based on tetraglycidyl bis(aminophenyl)methane and/or its condensation product. Component (B) is 50% by weight
If it exceeds 10% by weight, the pot life of the resin composition will decrease, while if it is less than 10% by weight, the effect of improving flexibility will be small, which is not preferable. In the present invention, it is also possible to use other epoxy resins in combination without impairing the purpose of the present invention. Known epoxy curing agents can be used in the present invention, such as diaminodiphenyl sulfone compounds, diaminodiphenylmethane compounds, dicyandiamide, tetramethylguanadine, phenol novolac resins, acid anhydrides, and aromatic amines. , aliphatic amines, boron trifluoride complexes, and the like. Among these, diaminodiphenyl sulfone compounds (DDS), diaminodiphenylmethane compounds (DDM) and acid anhydrides are preferred, with DDS and/or DDM being particularly preferred. Specifically, DDS, DDM is 4,4'-
Examples include diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, and these can be used alone or in a mixture of two or more. be done. In addition, acid anhydrides include tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, dodecenylsuccinic anhydride, nadic anhydride, methylnadic anhydride, phthalic anhydride, and pyromellitic anhydride. , benzophenonetetracarboxylic anhydride, methylcyclohexenetetracarboxylic anhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic dianhydride, 1-methyl-3,4 -dicarboxy-1,2,3,4-tetrahydro-1-
One or more types of naphthalene succinic dianhydride may be used. The polyglycidyl derivative used in the present invention has particularly excellent affinity with diaminodiphenyl sulfone and diaminodiphenylmethane compounds, and the resulting resin is easy to handle and has good homogeneity in terms of physical properties. In the present invention, when the resin composition is used for a prepreg, a diaminodiphenyl sulfone compound and a diaminodiphenylmethane compound may be prepolymerized in advance in order to adjust the viscosity. The usage ratio of the epoxy curing agent is preferably 0.4 to 1.4 times the amount theoretically calculated from the total amount of epoxy groups in the mixture of epoxy resin and epoxy resin.
More preferably, the amount is in the range of 0.5 to 1.2 times. Furthermore, if necessary, conventionally known tertiary amines, phenol compounds, imidazoles, Lewis acids, etc. may be added as curing accelerators within a range that does not impair the object of the present invention. Examples of fibers used as reinforcing materials in the present invention include carbon fibers, graphite fibers, glass fibers, silicon carbide fibers, alumina fibers, titania fibers, boron nitride fibers, aromatic polyamide fibers, aromatic polyester fibers, and polybenzimidazole fibers. , tensile strength
Examples include inorganic or organic fibers having a Young's modulus of 0.5 GPa or more and a Young's modulus of 50 GPa or more. These fibers can be used in the form of continuous tows, woven fabrics, short fibers, whiskers, and the like. Furthermore, depending on the purpose of use, it is also possible to use two or more types of fibers or fibers with different shapes.
Furthermore, in addition to reinforcing fibers, mixing particulate materials such as talc, mica, calcium carbonate, alumina hydrate, silicon carbide, carbon black, and silica improves the viscosity of the resin composition and makes it easier to mold the composite material. It is also effective for improving the physical properties of the resulting composite material, such as compressive strength. As a method for manufacturing the composite material of the present invention, any method such as a method for manufacturing a fiber-reinforced composite material using an epoxy resin as a matrix, which is conventionally known, can be adopted. One example is a method of laminating a plurality of sheet prepregs and heating and pressurizing them in an autoclave to obtain a composite material. The prepreg herein refers to reinforcing fibers impregnated with the resin composition, and takes the form of sheets, continuous tows, strands, yarns, or pellets. In sheet-like materials, the reinforcing fibers are in the form of continuous tows aligned, short fibers entwined in a mat shape, or woven fabric. Also useful are laminated sheet prepregs made by stacking several of these sheets with different structures, and a bundle of several continuous tow prepregs. The fiber content of these prepregs is generally 5 to 70
Volume % is preferred, especially 10 to 60 volume %. A fiber-reinforced composite material can be obtained by forming these prepregs into a desired shape by stacking or winding them, and then heating and pressurizing them. Further, when a low-viscosity polyglycidyl derivative is used, it is particularly effective in terms of moldability in the filament winding method. [Effects of the Invention] As explained above, the fiber-reinforced composite material of the present invention has excellent heat resistance, water resistance, and flexibility, and also exhibits good bending strength, bending elastic modulus, and interlaminar shear strength. It can be used for various purposes. [Examples] Example 1 (A)N,N,N',N'-tetraglycidylbis(aminophenyl)methane (Sumi Epoxy ELM-434 [manufactured by Sumitomo Chemical Co., Ltd.]) with an epoxy equivalent of 120 80
g, 200 g of triglycidyl-4-amino-m-cresol with an epoxy equivalent of 105 and 425 g of 4,4'-diaminodiphenylsulfone were added to methyl ethyl ketone.
A matrix resin composition was prepared by dissolving 1450 g of the resin. Next, carbon fiber (Magnamite AS-
4 (manufactured by Sumika Hercules Co., Ltd.) was aligned in one direction, impregnated with the resin solution, and dried at 120° C. for 5 minutes to produce a prepreg. The epoxy resin composition squeezed out from this carbon fiber prepreg exhibits a low activity of 10.5 poise or less at 50°C, and due to the easily controllable low-temperature reaction behavior, a prepreg with appropriate flexibility can be easily obtained. Tg was 265°C, and the pot life was over 24 hours. Note that the carbon fiber content in the prepreg was adjusted to 60% by volume. The obtained prepreg was placed in a matte die mold so that the carbon fiber content after molding was 60% by volume, and heated and pressure molded for 1 hour in a hot press heated to 160°C. Post-curing was performed at 180° C. for 4 hours in a hot air circulation oven to completely cure the product to obtain a unidirectionally reinforced carbon fiber reinforced composite material molded article (CFRP board) with a thickness of 2 mm. The heat distortion temperature of the molded body was 260°C. Next, the bending strength and ILSS of the obtained CFRP plate
was measured in accordance with ASTM D-790 and ASTM D-2344. The results are shown in Table 1.

[Table] Comparative Example 1 (A)N,N,N',N'-tetraglycidylbis(aminophenyl)methane (Sumiepoxy ELM-434 (manufactured by Sumitomo Chemical Co., Ltd.)) with an epoxy equivalent of 120 1000
g, 4,4'-diaminodiphenyl sulfone 413 g
was dissolved in 1450 g of methyl ethyl ketone to prepare a matrix resin composition. Next, a prepreg was prepared in the same manner as in Example 1, and then heated at 170°C for 1
After time press molding, post-curing was performed at 180° C. for 4 hours to completely cure the product to obtain a unidirectionally reinforced carbon fiber reinforced composite material molded article (CFRP board) with a thickness of 2 mm. The heat distortion temperature of the molded body was 245°C. Next, the bending strength and ILSS of the obtained CFRP plate
was measured under the same conditions as in Example 1. The results are shown in Table 2.

[Table] Comparative Example 2 (A)N,N,N',N'-tetraglycidylbis(aminophenyl)methane with epoxy equivalent of 120 (Sumiepoxy ELM-434 (manufactured by Sumitomo Chemical Co., Ltd.)) 800
g and epoxy equivalent of 120 (Sumi epoxy ELM-
120 (manufactured by Sumitomo Chemical Co., Ltd.) and 413 g of 4,4'-diaminodiphenylsulfone were mixed into methyl ethyl ketone.
A matrix resin composition was prepared by dissolving 1450 g of the resin. Next, a prepreg was produced in the same manner as in Example 1, and after press molding at 170°C for 1 hour, it was heated to 180°C.
Post-curing was performed at ℃ for 4 hours to completely cure the product to obtain a unidirectionally reinforced carbon fiber reinforced composite material molded article (CFRP board) with a thickness of 2 mm. The heat distortion temperature of the molded product was 230°C. Next, the bending strength and ILSS of the obtained CFRP plate
was measured under the same conditions as in Example 1. The results are shown in Table 3.

【table】

Claims (1)

[Scope of Claims] 1 (A) N,N,N',N'-tetraglycidylbis(aminophenyl)methane and/or its condensation product; (B) an aromatic ring substituted with at least one alkyl group; Heat resistant, characterized in that the matrix is a cured product of an epoxy resin composition containing a polyglycidyl derivative of an aminophenol compound and/or a condensate thereof, and (C) an epoxy curing agent, and fibers are used as a reinforcing material. Composite material. 2 The aminophenol compound is 4-amino-m-
The heat-resistant composite material according to claim 1, which is cresol and/or 4-amino-o-cresol. 3. The heat-resistant composite material according to claim 1, wherein the epoxy curing agent is a diaminodiphenyl sulfone compound and/or a diaminodiphenylmethane compound.