RESIN COMPOSITION FOR FIBER-REINFORCED PLASTIC, AND FIBERREINFORCED PLASTIC CONTAINING SAID COMPOSITION

Abstract

A resin composition for fiber-reinforced plastic having a good balance between stability and curability and capable of producing fiber-reinforced plastic with improved strength. The composition contains an epoxy resin, an acid anhydride, and a catalyst that is liquid at 25° C. The catalyst is at least one member selected from the group consisting of a compound composed of an acid and a base and a compound composed of a quaternary onium cation and an anion.

Claims

1. A resin composition for fiber-reinforced plastic comprising (A) an epoxy resin, (B) an acid anhydride, and (C) a catalyst that is liquid at 25° C., the catalyst (C) comprising at least one member selected from the group consisting of (c1) a compound composed of an acid and a base and (c2) a compound composed of a quaternary onium cation and an anion.

2. The resin composition according to claim 1, wherein the epoxy resin (A) comprises a polyglycidyl ether of a bisphenol-alkylene oxide adduct.

3. The resin composition according to claim 2, wherein the polyglycidyl ether of a bisphenol-alkylene oxide adduct is present in an amount of 10 to 80 mass % relative to the epoxy resin (A).

4. The resin composition according to claim 1, wherein the epoxy resin (A) comprises a dicyclopentadiene epoxy resin represented by formula (1): ##STR00003## where R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a methyl group.

5. The resin composition according to claim 4, wherein the dicyclopentadiene epoxy resin is present in an amount of 0.1 to 30 mass % relative to the epoxy resin (A).

6. The resin composition according to claim 1, wherein the acid anhydride (B) is liquid at 25° C.

7. The resin composition according to claim 1, wherein the acid anhydride (B) comprises an unsaturated alicyclic polycarboxylic acid anhydride.

8. The resin composition according to claim 1, wherein the catalyst (C) is the compound (c1), the compound (c1) being a compound derived from an aromatic compound and an organic basic compound.

9. The resin composition according to claim 1, wherein the compound (c1) is a compound derived from a monocyclic aromatic compound and a nitrogen-containing heterocyclic compound.

10. The resin composition according to claim 1, wherein the catalyst (C) is the compound (c2), the compound (c2) being a compound derived from a phosphonium cation and an organic anion.

11. The resin composition according to claim 10, wherein the organic anion is an alkylphosphorodithioate anion.

12. The resin composition according to claim 1, wherein the catalyst (C) is present in an amount of 0.01 to 20 parts by mass per 100 parts by mass of the epoxy resin (A).

13. The resin composition according to claim 1, further comprising (D) a silane coupling agent.

14. A cured product obtained by curing the resin composition according to claim 1.

15. A fiber-reinforced plastic obtained by curing a composition comprising the resin composition according to claim 1 and reinforcing fibers.

16. A method for producing a cured product comprising providing the resing composition of claim 1, and curing the composition.

17. A method for producing a fiber-reinforced plastic comprising providing a composition comprising the resin composition of claim 1, adding reinforcing fibers to the composition, and curing the composition.

18. The resin composition according to claim 2, wherein the epoxy resin (A) comprises a dicyclopentadiene epoxy resin represented by formula (1): ##STR00004## where R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a methyl group.

19. The resin composition according to claim 3, wherein the epoxy resin (A) comprises a dicyclopentadiene epoxy resin represented by formula (1): ##STR00005## where R.sup.1 and R.sup.2 each independently represent a hydrogen atom or a methyl group.

20. The resin composition according to claim 2, wherein the acid anhydride (B) is liquid at 25° C.

Description

EXAMPLES

[0069] The invention will now be illustrated in greater detail with reference to Examples. The amounts of the components shown in Tables 1 and 2 are given in part by mass.

Example 1

[0070] The components shown in Table 1 were placed in a 500 mL disposable cup in the ratio shown (in part by mass) and stirred with a spatula at 25° C. for 5 minutes. The mixture was further stirred in a planetary stirrer to prepare a resin composition. The components listed in Table 1 are as follows.

Epoxy resins (Adeka Resin series from Adeka Corp.): [0071] EP-4901E (bisphenol F epoxy resin; epoxy equiv.: 170 g/eq) [0072] EP-4005 (polyglycidyl ether of bisphenol A-propylene oxide adduct; epoxy equiv.: 510 g/eq) [0073] EP-4088S (dicyclopentadiene epoxy resin of formula (1) in which R.sup.1=R.sup.2=H; epoxy equiv.: 170 g/eq)
Acid anhydride: HN-2000, from Hitachi Chemical Co., Ltd. (methyltetrahydrophthalic anhydride, liquid at 25° C.; viscosity (25° C.): 38 mPa.Math.s)

Catalysts:

[0074] Hishicolin PX-4ET, from Nippon Chemical Industrial Co., Ltd. (tetrabutylphosphonium O,O-diethylphosphorodithioate, liquid at 25° C.; viscosity (25° C.): 1000 mPa.Math.s) [0075] U-CAT SA-1, from San-Apro Ltd. (DBU phenol salt, liquid at 25° C.; viscosity (25° C.): 320 mPa.Math.s) [0076] Adeka Hardener, from Adeka Corp. (1,3,5-trisdimethylaminomethylphenol)
Silane coupling agent: KBM-403, from Shin-Etsu Chemical Co., Ltd. (γ-glycidoxypropyltriethoxysilane)

Example 2 and Comparative Examples 1 and 2

[0077] Resin compositions were prepared in the same manner as in Example 1, except for changing the mixing ratio of the components as shown in Table 1.

[0078] The ratio of the acid anhydride to the epoxy resin in every resin composition prepared in Examples 1 and 2 and Comparative Examples 1 and 2 was one acid anhydride group per one epoxy group.

[0079] The resin compositions prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated as follows. The results obtained are shown in Table 1.

(1) Rate of Viscosity Increase

[0080] The viscosity increase rate (%) of the resin compositions prepared in Examples 1 and 2 and Comparative Examples 1 and 2 was obtained by the method previously described. The viscosity of these resin compositions at 25° C. was measured by the method described above.

(2) Degree of Cure

[0081] The resin compositions prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were cured by heating at 100° C. for 1 hour. The degree of cure of the resulting samples was measured in accordance with JIS K7148-1.

TABLE-US-00001 TABLE 1 Example Comparative Example Component 1 2 1 2 Epoxy Resin EP-4901E 63 63 63 63 EP-4005 25 25 25 25 EP-4088S 10 10 10 Acid Anhydride HN-2000 81 81 81 81 Catalyst PX-4ET 5 SA-1 5 EHC-30 5 1 Silane Coupling Agent KBM-403 2 2 2 2 Viscosity Increase Rate (%) 135 163 510 151 Viscosity (Pa .Math. s) 500 500 1100 270 Degree of Cure 98.0 93.0 97.0 79.0

[0082] As is apparent from Table 1, the resin compositions of Examples 1 and 2 have a small viscosity increase, proving excellent in stability. It is also clear that the resin compositions of Examples 1 and 2 are suitable as a resin matrix material for making FRP as is verified by the high degree of cure of the cured products obtained therefrom.

Examples 3 and 4

[0083] A carbon fiber-reinforced plastic (CI-RP) for evaluation of physical properties was produced by filament winding and subjected to the testing described below. CFRP was formed by impregnating a roving with the resin composition kept at 25° C. in a resin bath, hoop-winding the impregnated roving onto a flat mandrel to a prescribed thickness of 3 to 4 mm, and curing the resin by press heating at 100° C. for 1 hour. The resin composition to carbon fiber ratio was 50:100 by mass.

[0084] The following evaluation was conducted using the resulting test specimens. The results are shown in Table 2.

Methods for Testing Physical Properties:

[0085] The bending strength (MPa) and interlaminar shear strength (MPa) of the cured product were determined in accordance with JIK K-7074 and K7078, respectively.

TABLE-US-00002 TABLE 2 Example Component 3 4 Epoxy Resin EP-4901E 63 63 EP-4005 25 25 EP-4088S 10 10 Acid Anhydride HN-2000 81 81 Catalyst PX-4ET 5 SA-1 5 Silane Coupling KBM-403 2 2 Agent CFRP Physical Bending Strength 1230 1250 Properties Interlaminar Shear Strength 62.0 65.0

[0086] As is apparent from Table 2, the CFRPs obtained in Examples 3 and 4 had sufficient bending strength and interlaminar shear strength for practical use.