Epoxy resin composition, prepreg, and carbon fiber-reinforced composite material

Abstract

An object of the present invention is to provide an epoxy resin composition capable of providing a carbon fiber-reinforced composite material that is excellent in moldability, heat resistance, and mechanical properties such as tensile strength and compression strength, and a prepreg. The present invention provides an epoxy resin composition containing at least components [A] to [D] shown below: [A]: an epoxy resin having a xylene group; [B]: a glycidyl amine epoxy resin having three or more glycidyl groups in a molecule; [C]: a thermoplastic resin; and [D]: an aromatic polyamine, the epoxy resin composition containing 10 to 80 parts by mass of the component [A] and 20 to 90 parts by mass of the component [B] based on 100 parts by mass in total of epoxy resins, and also 1 to 25 parts by mass of the component [C] based on 100 parts by mass in total of epoxy resins.

Claims

1. An epoxy resin composition comprising at least components [A] to [D] shown below: [A]: an epoxy resin having a xylene group; [B]: a glycidyl amine epoxy resin having three or more glycidyl groups in a molecule; [C]: a thermoplastic resin; and [D]: an aromatic polyamine, wherein: the epoxy resin composition comprising 10 to 80 parts by mass of the component [A] and 90 to 20 parts by mass of the component [B] based on 100 parts by mass in total of epoxy resins, and also 1 to 25 parts by mass of the component [C] based on 100 parts by mass in total of epoxy resins, a mixing ratio [A]/[B] between the component [A] and the component [B] being 0.25 to 2.3, and the component [A] having an epoxy equivalent of 200 to 350 g/eq.

2. The epoxy resin composition according to claim 1, comprising 40 to 80 parts by mass of the component [A] and 60 to 20 parts by mass of the component [B] based on 100 parts by mass in total of epoxy resins.

3. The epoxy resin composition according to claim 2, wherein the component [D] is an aromatic polyamine having 1 to 4 phenyl groups in a molecule, and at least one of the phenyl groups has an amino group at an ortho position or a meta position.

4. A prepreg comprising a carbon fiber, and the epoxy resin composition according to claim 2 impregnated into the carbon fiber.

5. A carbon fiber-reinforced composite material comprising a cured product of the epoxy resin composition according to claim 2, and a carbon fiber.

6. The epoxy resin composition according to claim 1, wherein the component [D] is an aromatic polyamine having 1 to 4 phenyl groups in a molecule, and at least one of the phenyl groups has an amino group at an ortho position or a meta position.

7. A prepreg comprising a carbon fiber, and the epoxy resin composition according to claim 6 impregnated into the carbon fiber.

8. A prepreg comprising a carbon fiber, and the epoxy resin composition according to claim 1 impregnated into the carbon fiber.

9. The prepreg according to claim 8, wherein the carbon fiber is in a form of a woven fabric.

10. A carbon fiber-reinforced composite material that is a cured product of the prepreg according to claim 9.

11. A carbon fiber-reinforced composite material that is a cured product of the prepreg according to claim 8.

12. A carbon fiber-reinforced composite material comprising a cured product of the epoxy resin composition according to claim 1, and a carbon fiber.

Description

EXAMPLES

(1) Hereinafter, the present invention is described in more detail by way of examples. Various physical properties were measured by the following methods. Unless otherwise noted, the physical properties were measured in an environment at a temperature of 23° C. and 50% relative humidity.

(2) Component [A] “jER (registered trademark)” YX7700 (phenol-modified xylene resin type epoxy manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 270 g/eq)

(3) Component [B] “ARALDITE (registered trademark)” MY721 (tetraglycidyl diaminodiphenylmethane manufactured by Huntsman Advanced Materials LLC, epoxy equivalent: 112 g/eq) “TGDDS (tetraglycidyl diaminodiphenyl sulfone manufactured by Konishi Chemical Ind. Co., Ltd., epoxy equivalent: 112 g/eq) “ARALDITE (registered trademark)” (registered trademark) MY0510 (triglycidyl-p-aminophenol manufactured by Huntsman Advanced Materials LLC, epoxy equivalent: 100 g/eq) “ARALDITE (registered trademark)” registered trademark) MY0600 (triglycidyl-m-aminophenol manufactured by Huntsman Advanced Materials LLC, epoxy equivalent: 105 g/eq)

(4) Component [C] “Sumika Excel (registered trademark)” PES5003P (hydroxyl group-terminated polyethersulfone manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, Tg=225° C.) “Virantage (registered trademark)” VW-10700RP (hydroxyl group-terminated polyethersulfone manufactured by Solvay Advanced Polymers LLC, Tg=220° C.) “Sumika Excel (registered trademark)” PES7600P (chlorine-terminated polyethersulfone manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, Tg=225° C.) “Virantage (registered trademark)” VW-30500RP (polysulfone manufactured by Solvay Advanced Polymers LLC, Tg=205° C.) “ULTEM (registered trademark)” 1010 (polyetherimide manufactured by Sabic Innovative Plastics, Tg=215° C.)

(5) Component [D] 3,3′-DAS (3,3′-diaminodiphenyl sulfone manufactured by Mitsui Fine Chemicals, Inc., active hydrogen equivalent: 62 g/eq, solid at 23° C.) SEIKACURE S (4,4′-diaminodiphenyl sulfone manufactured by Wakayama Seika Kogyo Co., Ltd., active hydrogen equivalent: 62 g/eq, solid at 23° C.) “Lonzacure (registered trademark)” MIPA (4,4′-methylenebis(2-methyl-6-isopropyl)benzenamine manufactured by Lonza, active hydrogen equivalent: 78 g/eq, solid at 23° C.)

(6) Component [E] “jER (registered trademark)” 825 (phenol A type epoxy manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 175 g/eq)

(7) Novolac epoxy resin “EPICLON (registered trademark)” N-775 (phenol-modified novolac epoxy resin manufactured by DIC Corporation, epoxy equivalent: 190 g/eq)

(8) Active ester resin “EPICLON (registered trademark)” HPC-8000-65T (manufactured by DIC Corporation, active group equivalent: 223 g/eq, a toluene solution having a nonvolatile content of 65 mass %)

(9) Accelerator 4-Dimethylaminopyridine (manufactured by Tokyo Chemical Industry Co., Ltd.), used in the state of a solution adjusted by MEK (manufactured by Wako Pure Chemical Industries, Ltd.) so that the solid content will be 2 mass %

(10) (1) Preparation of Epoxy Resin Composition

(11) In Examples 1 to 13 and Comparative Examples 1 to 4, 6, and 7, the epoxy resin as the component [B] and the thermoplastic resin as the component [C] were heated and kneaded to dissolve the component [C], whereby a transparent viscous liquid was obtained. The epoxy resin as the component [A] and the hardener as the component [D] were added to the liquid and the resulting mixture was kneaded to produce an epoxy resin composition. The compounding ratios among components (parts by mass) of examples and comparative examples are as shown in Tables 1 to 3.

(12) In Comparative Example 5, the epoxy resin as the component [B] and the thermoplastic resin as the component [C] were heated and kneaded to dissolve the component [C], whereby a transparent viscous liquid was obtained. The epoxy resin as the component [A], 180 parts by mass of a solution containing an active ester resin, and 6 parts by mass of a solution containing an accelerator were added to the liquid and the resulting mixture was kneaded to produce an epoxy resin composition. The compounding ratio among components of Comparative Example 5 is as shown in Table 3.

(13) (2) Bending Test of Cured Resin

(14) In Examples 1 to 13 and Comparative Examples 1 to 4, 6, and 7, the uncured resin composition was defoamed in a vacuum, and then cured in a mold set to a thickness of 2 mm with a 2-mm thick “TEFLON (registered trademark)” spacer at a temperature of 180° C. for 2 hours. The obtained cured resin having a thickness of 2 mm was cut to a width of 10±0.1 mm and a length of 60±1 mm to produce a test piece. Using an Instron universal tester (manufactured by Instron), 3-point bending was performed at a span interval of 32 mm according to JIS-K7171 (1994), and the elastic modulus was measured. The number of measurements was N=6, and the average of the measured values was determined.

(15) In Comparative Example 5, the same operation as described above was performed except that the obtained epoxy resin composition was poured into a mold set to a thickness of 2 mm with a 2-mm thick “TEFLON (registered trademark)” spacer, vacuuming was performed at 70° C. for 24 hours, toluene and MEK were removed, and then the uncured resin composition was cured in the mold at a temperature of 100° C. for 30 minutes and at a temperature of 180° C. for 2 hours. A cured resin having an elastic modulus of 4.0 GPa or more was rated as pass.

(16) (3) Bending Test of Moistened Cured Resin in High-Temperature Environment

(17) The test piece produced to have the dimensions described in item (2) was immersed in a thermostatic water bath at 98° C. for 20 hours. Then, the thermostat bath installed in the Instron universal tester (manufactured by Instron) described in item (2) was set to 121° C., the test piece was kept in the environment within the bath for 3 minutes, and then the elastic modulus was measured under the same measurement conditions as in item (2). A cured resin having an elastic modulus in a moistened high-temperature environment of 2.4 GPa or more was rated as pass.

(18) (4) Tg of Cured Resin

(19) As for the glass transition temperature of the cured resin obtained in item (2), the midpoint temperature determined according to JIS-K7121 (1987) using a differential scanning calorimeter (DSC) was regarded as Tg. A cured resin having a Tg of 165° C. or higher was rated as pass.

(20) (5) Production of Woven Fabric Prepreg

(21) The epoxy resin composition prepared in item (1) was applied to release paper to produce a resin film having a predetermined resin areal weight. The resin films were set in a prepreg production machine, and laminated on both surfaces of a reinforced fiber woven fabric, and the resulting laminate was heated and pressurized to impregnate the thermosetting resin composition into the woven fabric. In this manner, a woven fabric prepreg having a fiber areal weight of 193 g/m.sup.2 and a resin content of 38 mass % was produced. The reinforced fiber woven fabric used was a plain weave fabric made of “TORAYCA (registered trademark)” T400H-3K (number of fibers: 3,000, tensile strength: 4,410 MPa, tensile modulus: 250 MPa, tensile elongation: 1.8%). In Comparative Example 5, toluene and MEK were removed from the epoxy resin composition and then the epoxy resin composition was applied to release paper.

(22) (6) Tensile Test of Fiber-Reinforced Composite Material

(23) Woven fabric prepregs were laminated with the warp directions of the prepregs being aligned, and the resulting laminate was heated and pressurized to cure in an autoclave at a temperature of 180° C. and a pressure of 6.1 kgf/cm.sup.2 for 2 hours, whereby a composite material was produced. From the obtained composite material, a test piece having a width of 25±0.5 mm, a length of 250±1.0 mm, and a span between tabs of 130±1.0 mm was produced, and the tensile strength of the warp was measured according to EN2597B. A composite material having a tensile strength of the warp of 770 MPa or more was rated as pass.

(24) (7) Compression Test of Fiber-Reinforced Composite Material

(25) Nine woven fabric prepregs were laminated with the warp directions of the prepregs being aligned, and the resulting laminate was molded into a composite material under the molding conditions as in item (6). From the composite material, a test piece having a width of 12.5±0.2 mm, a length of 75 to 80 mm, and a span between tabs of 5.25±0.25 mm was produced, and the compression strength of the warp was measured according to EN2850B. A composite material having a compression strength of the warp of 840 MPa or more was rated as pass.

(26) TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Component [A] YX7700 50 60 80 40 40 50 50 Component [B] MY721 50 TGDDS 20 50 MY0510 40 50 MY0600 60 60 Component [C] PES5003P 5 1 VW-10700RP 25 PES7600P 10 10 VW-30500RP 10 “ULTEM (registered 5 trademark)” 1010 Component [D] 3,3′-DAS 45 45 50 50 SEIKACURE S 50 50 “Lonzacure 35 (registered trademark)” MIPA Component [E] jER825 Novolac epoxy N-775 resin Active ester HPC-8000-65T resin Accelerator 4-Dimethyl aminopyridine [A]/[B] 1.0 1.5 4.0 0.67 0.67 1.0 1.0 Amount of [C] to 100 parts by mass 5 5 10 10 10 25 1 in total of epoxy resins Elastic modulus of cured resin 4.4 4.2 4.0 4.6 4.1 4.2 4.1 [GPa] Elastic modulus of cured resin in 3.1 2.9 2.8 2.7 2.5 2.7 2.9 moistened high-temperature environment [GPa] Tg of cured resin [° C.] 191 189 198 182 199 181 183 Tensile strength of warp [MPa] 817 805 794 800 791 847 842 Compression strength of warp [MPa] 888 870 850 905 864 872 864

(27) TABLE-US-00002 TABLE 2 Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Component [A] YX7700 10 80 20 70 30 30 Component [B] MY721 90 20 80 30 70 70 TGDDS MY0510 MY0600 Component [C] PES5003P 5 5 5 5 VW-10700RP PES7600P VW-30500RP 10 10 “ULTEM (registered trademark)” 1010 Component [D] 3,3′-DAS 45 45 45 45 35 SEIKACURE S 35 “Lonzacure (registered trademark)” MIPA Component [E] jER825 Novolac epoxy N-775 resin Active ester HPC-8000-65T resin Accelerator 4-Dimethyl aminopyridine [A]/[B] 0.11 4.0 0.25 2.3 0.43 0.43 Amount of [C] to 100 parts by mass 5 5 5 5 10 10 in total of epoxy resins Elastic modulus of cured resin 4.4 4.3 4.5 4.4 4.4 4.0 [GPa] Elastic modulus of cured resin in 2.4 2.7 2.5 2.8 2.6 2.4 moistened high-temperature environment [GPa] Tg of cured resin [° C.] 221 168 214 176 190 206 Tensile strength of warp [MPa] 772 840 775 875 803 770 Compression strength of warp [MPa] 840 860 880 875 862 851

(28) TABLE-US-00003 TABLE 3 Comparative Comparative Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Component [A] YX7700 90 40 40 50 5 95 Component [B] MY721 50 90 5 TGDDS 10 MY0510 MY0600 60 60 60 Component [C] PES5003P 5 5 5 VW-10700RP 10 30 PES7600P 10 VW-30500RP “ULTEM (registered trademark)” 1010 Component [D] 3,3′-DAS 45 45 SEIKACURE S 50 50 50 “Lonzacure 35 (registered trademark)” MIPA Component [E] jER825 5 Novolac epoxy N-775 40 resin Active ester HPC-8000-65T 180 resin Accelerator 4-Dimethyl 6 aminopyridine [A]/[B] 9.0 0.67 0.67 — 1.0 0.06 19 Amount of [C] to 100 parts by mass 10 0 30 17 5 5 5 in total of epoxy resins Elastic modulus of cured resin 3.7 4.2 3.9 3.6 3.7 4.3 4.3 [GPa] Elastic modulus of cured resin in 2.4 2.6 2.1 2.2 2.6 2.3 2.5 moistened high-temperature environment [GPa] Tg of cured resin [° C.] 170 200 190 221 210 213 157 Tensile strength of warp [MPa] 880 730 854 721 757 725 801 Compression strength of warp [MPa] 825 870 810 818 827 880 855

Examples 1 to 13

(29) As shown in Tables 1 and 2, in Examples 1 to 13, the components [A], [B], [C], and [D] were blended, and the resulting cured resins and fiber-reinforced composite materials were tested. For all the physical properties including the elastic modulus, Tg, tensile strength of the warp, and the compression strength of the warp, good results were obtained.

Comparative Examples 1 to 7

(30) As shown in Table 3, when too large an amount of the component [A] was blended as in Comparative Example 1, the elastic modulus of the cured resin, the Tg of the cured resin, and the compression strength of the warp decreased. When the epoxy resin composition did not contain the component [C] as in Comparative Example 2, the tensile strength of the warp decreased. When too large an amount of the component [C] was blended as in Comparative Example 3, all of the elastic modulus of the cured resin, the elastic modulus of the cured resin in a moistened high-temperature environment, and the compression strength of the warp decreased. When the epoxy resin composition contained a novolac epoxy resin instead of the component [A] as in Comparative Example 4, the elastic modulus of the cured resin, the elastic modulus of the cured resin in a moistened high-temperature environment, the tensile strength of the warp, and the compression strength of the warp decreased. When the epoxy resin composition contained an active ester resin as a hardener and 4-dimethylaminopyridine as an accelerator instead of the component [D] as in Comparative Example 5, the elastic modulus of the cured resin, the tensile strength of the warp, and the compression strength of the warp decreased. When too small an amount of the component [A] was blended and the component [E] was blended instead as in Comparative Example 6, the elastic modulus of the cured resin in a moistened high-temperature environment, and the tensile strength of the warp decreased. When too large an amount of the component [A] was blended as in Comparative Example 7, the Tg of the cured resin significantly decreased.