Prepreg, fiber-reinforced composite material, and molded article

Abstract

A prepreg comprising: carbon fibers; and a resin composition containing an epoxy resin having a biphenyl structure, a curing agent, and melamine cyanurate.

Claims

1. A prepreg comprising: carbon fibers; and a resin composition comprising an epoxy resin (A) having a biphenyl structure and two or more epoxy groups, an epoxy resin (B) having two or more epoxy groups and having no biphenyl structure, a curing agent, and melamine cyanurate, wherein a content of chlorine atoms in the resin composition is 1% by mass or less, a content of phosphorus atoms in the resin composition is 0.1% by mass or less, a content of the epoxy resin (A) with respect to the total amount of the epoxy resin (A) and the epoxy resin (B) is 20% by mass or more and 40% by mass or less, the total amount of the epoxy resin (A) and the epoxy resin (B) is 60% by mass or more and 75% by mass or less based on the total amount of the resin composition, a content of the melamine cyanurate is 25% by mass or more and 40% by mass or less based on the total amount of the resin composition, a content of the carbon fibers in the prepreg is 20% by mass or more and 90% by mass or less, and the epoxy resin (A) comprises an epoxy resin represented by the formula (A-1): ##STR00002## wherein n is an integer of 1 or more.

2. A fiber-reinforced composite material obtained by laminating and curing a plurality of prepregs, wherein at least one of the prepregs is a prepreg according to claim 1.

3. The fiber-reinforced composite material according to claim 2, wherein a thickness in a laminating direction is 1.5 mm or less.

4. The fiber-reinforced composite material according to claim 2, wherein a flame retardancy as evaluated by the UL94 burning test is V-0 or V-1.

5. A molded article comprising the fiber-reinforced composite material according to claim 2.

6. A molded article comprising the fiber-reinforced composite material according to claim 3.

7. A molded article comprising the fiber-reinforced composite material according to claim 4.

Description

EXAMPLES

(1) Hereinafter, the present invention will be described in detail by Examples, and the present invention is not limited to these Examples.

Example A-1

(2) 40 parts by mass of an epoxy resin having a biphenyl structure (NC-3000, manufactured by Nippon Kayaku Co., Ltd.), 14 parts by mass of a bisphenol A epoxy resin (YD-128, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), 20 parts by mass of a phenol novolac epoxy resin (YDPN-638, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), 40 parts by mass of melamine cyanurate (MC-6000, manufactured by Nissan Chemical Co., Ltd.), 4 parts by mass of dicyandiamide (DICY), and 3 parts by mass of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) were mixed to obtain a resin composition A-1. The viscosity of the obtained resin composition A-1 at 30° C. was 60100 Pa.Math.s. In addition, the glass transition temperature of the resin cured product after curing at 140° C. for 2 hours was 155° C., and a flame retardancy evaluation equivalent to the UL 94 burning test showed that the result was equivalent to V-0.

(3) XN-80 (manufactured by Nippon Graphite Fiber Co., Ltd, and tensile elastic modulus of 780 GPa) was prepared as carbon fibers, and these carbon fibers were impregnated with the resin composition A-1. Thereby, a prepreg (prepreg A-1) with a number of carbon fibers per unit area of 125 g/m.sup.2 and a resin content of 32% was obtained.

Example A-2

(4) A resin composition A-2 was obtained in the same manner as in Example A-1, except that the loadings of the epoxy resin having a biphenyl structure, the bisphenol An epoxy resin, and the phenol novolac epoxy resin were changed to 35 parts by mass, 19 parts by mass, and 13 parts by mass, respectively. The viscosity of the obtained resin composition A-2 at 30° C. was 22100 Pa.Math.s. In addition, the glass transition temperature of the resin composition after curing at 140° C. for 2 hours was 151° C., and a flame retardancy evaluation equivalent to the UL 94 burning test showed that the result was equivalent to V-0.

(5) A prepreg was produced in the same manner as in Example A-1 except that the resin composition A-2 was used instead of the resin composition A-1, and the prepreg with a number of carbon fibers per unit area of 125 g/m.sup.2 and a resin content of 32% (prepreg A-2) was obtained.

Example A-3

(6) A resin composition A-3 was obtained in the same manner as in Example A-1, except that the loadings of the epoxy resin having a biphenyl structure, the bisphenol An epoxy resin, and the phenol novolac epoxy resin were changed to 30 parts by mass, 14 parts by mass, and 23 parts by mass and 5 parts by mass of a phenoxy resin (YP-70, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) were further mixed. The viscosity of the obtained resin composition A-3 at 30° C. was 113000 Pa.Math.s. In addition, the glass transition temperature after curing at 140° C. for 2 hours was 153° C., and a flame retardancy evaluation equivalent to the UL 94 burning test showed that the result was equivalent to V-0.

(7) A prepreg was produced in the same manner as in Example A-1 except that the resin composition A-3 was used instead of the resin composition A-1, and the prepreg with a number of carbon fibers per unit area of 125 g/m.sup.2 and a resin content of 32% (prepreg A-3) was obtained.

Example A-4

(8) A resin composition A-4 was obtained in the same manner as in Example A-1, except that the loadings of the epoxy resin having a biphenyl structure, the bisphenol An epoxy resin, and the phenol novolac epoxy resin were changed to 30 parts by mass, 32 parts by mass, and 0 parts by mass and 10 parts by mass of the phenoxy resin (YP-70, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) were further mixed. The viscosity of the obtained resin composition A-4 at 30° C. was 35000 Pa.Math.s. In addition, the glass transition temperature of the resin composition after curing at 140° C. for 2 hours was 128° C., and a flame retardancy evaluation equivalent to the UL 94 burning test showed that the result was equivalent to V-0.

(9) A prepreg was produced in the same manner as in Example A-1 except that the resin composition A-4 was used instead of the resin composition A-1, and the prepreg with a number of carbon fibers per unit area of 125 g/m.sup.2 and a resin content of 32% (prepreg A-4) was obtained.

Example A-5

(10) A prepreg was produced in the same manner as in Example A-2 except that T700S (manufactured by Toray industries, Inc. and tensile elastic modulus of 230 GPa) was used as carbon fibers, and the prepreg with a number of carbon fibers per unit area of 200 g/m.sup.2 and a resin content of 32% (prepreg A-5) was obtained.

Comparative Example X-1

(11) 37 parts by mass of the bisphenol An epoxy resin (YD-128, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), 33 parts by mass of the bisphenol An epoxy resin (YD-11, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), 30 parts by mass of the phenol novolac epoxy resin (YDPN-638, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), 15 parts by mass of the phenoxy resin (YP-70, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), 4 parts by mass of dicyandiamide (DICY), and 3 parts by mass of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) were mixed to obtain a resin composition X-1. The viscosity of the obtained resin composition X-1 at 30° C. was 24100 Pa.Math.s. In addition, the glass transition temperature of the resin cured product after curing at 140° C. for 2 hours was 131° C., and a flame retardancy evaluation equivalent to the UL 94 burning test showed that the result was equivalent to V-not.

(12) XN-80 (manufactured by Nippon Graphite Fiber Co., Ltd. and tensile elastic modulus of 780 GPa) was prepared as carbon fibers, and these carbon fibers were impregnated with the resin composition X-1. Thereby, a prepreg (prepreg X-1) with a number of carbon fibers per unit area of 125 g/m.sup.2 and a resin content of 32% was obtained.

Comparative Example X-2

(13) A resin composition X-2 was obtained in the same manner as in Comparative Example X-1, except that the loading of YD-11 was changed to 13 parts by mass and 20 parts by mass of melamine cyanurate (MC-6000, manufactured by Nissan Chemical Co., Ltd.) was further mixed. The viscosity of the obtained resin composition X-2 at 30° C. was 10600 Pa.Math.s. In addition, the glass transition temperature of the resin cured product after curing at 140° C. for 2 hours was 128° C., and a flame retardancy evaluation equivalent to the UL 94 burning test showed that the result was equivalent to V-2.

Comparative Example X-3

(14) A resin composition X-3 was obtained in the same manner as in Comparative Example X-2, except that the loadings of YP-70 and MC-6000 were changed to 5 parts by mass and 0 parts by mass, respectively, and 30 parts by mass of the epoxy resin having a biphenyl structure (NC-3000, manufactured by Nippon Kayaku Co., Ltd.) was further mixed. The viscosity of the obtained resin composition X-3 at 30° C. was 16600 Pa.Math.s. In addition, the glass transition temperature of the resin cured product after curing at 140° C. for 2 hours was 134° C., and a flame retardancy evaluation equivalent to the UL 94 burning test showed that the result was equivalent to V-not.

Example B-1

(15) Four prepregs A-1 were laminated and cured in an autoclave under the conditions of a pressure of 0.6 MPa and 140° C. for 2 hours to obtain a fiber-reinforced composite material plate with a thickness of 0.57 mm. For the obtained fiber-reinforced composite material plate, the result of a flame retardancy evaluation equivalent to the UL94 burning test was equivalent to V-0.

Example B-2

(16) Four prepregs A-2 were laminated and cured in an autoclave under the conditions of a pressure of 0.6 MPa and 140° C. for 2 hours to obtain a fiber-reinforced composite material plate with a thickness of 0.43 mm. For the obtained fiber-reinforced composite material plate, the result of a flame retardancy evaluation equivalent to the UL94 burning test was equivalent to V-0.

Example B-3

(17) Four prepregs A-3 were laminated and cured in an autoclave under the conditions of a pressure of 0.6 MPa and 140° C. for 2 hours to obtain a fiber-reinforced composite material plate with a thickness of 0.57 mm. For the obtained fiber-reinforced composite material plate, the result of a flame retardancy evaluation equivalent to the UL94 burning test was equivalent to V-0.

Example B-4

(18) Four prepregs A-4 were laminated and cured in an autoclave under the conditions of a pressure of 0.6 MPa and 140° C. for 2 hours to obtain a fiber-reinforced composite material plate with a thickness of 0.57 mm. For the obtained fiber-reinforced composite material plate, the result of a flame retardancy evaluation equivalent to the UL94 burning test was equivalent to V-1.

Example B-5

(19) Four prepregs A-5 were laminated and cured in an autoclave under the conditions of a pressure of 0.6 MPa and 140° C. for 2 hours to obtain a fiber-reinforced composite material plate with a thickness of 0.85 mm. For the obtained fiber-reinforced composite material plate, the result of a flame retardancy evaluation equivalent to the UL94 burning test was equivalent to V-0.

Example B-6

(20) Ten prepregs A-2 were laminated and cured in an autoclave under the conditions of a pressure of 0.6 MPa and 140° C. for 2 hours to obtain a fiber-reinforced composite material plate with a thickness of 1.1 mm. For the obtained fiber-reinforced composite material plate, the result of a flame retardancy evaluation equivalent to the UL94 burning test was equivalent to V-0.

Example B-7

(21) Three prepregs A-5 were laminated and cured in an autoclave under the conditions of a pressure of 0.6 MPa and 140° C. for 2 hours to obtain a fiber-reinforced composite material plate with a thickness of 0.67 mm. For the obtained fiber-reinforced composite material plate, the result of a flame retardancy evaluation equivalent to the UL94 burning test was equivalent to V-1.

Example B-8

(22) Five pieces of prepregs A-2 and prepregs A-5 were laminated in the order of A-2/A-2/A-5/A-2/A-2 and were cured in an autoclave under the conditions of a pressure of 0.6 MPa and 140° C. for 2 hours to obtain a fiber-reinforced composite material plate with a thickness of 0.65 mm. For the obtained fiber-reinforced composite material plate, the result of a flame retardancy evaluation equivalent to the UL94 burning test was equivalent to V-0.

Comparative Example Y-1

(23) 16 prepregs X-1 were laminated and cured in an autoclave under the conditions of a pressure of 0.6 MPa and 140° C. for 2 hours to obtain a fiber-reinforced composite material plate with a thickness of 2.4 mm. For the obtained fiber-reinforced composite material plate, the result of a flame retardancy evaluation equivalent to the UL94 burning test was equivalent to V-not.

INDUSTRIAL APPLICABILITY

(24) The prepreg according to the present invention can form a fiber-reinforced composite material that achieves both thinness and flame retardancy without using a halogenated flame retardant and a phosphorus-based flame retardant. Thus, the prepreg according to the present invention can be suitably used for applications such as a housing of electronic and electrical equipment.