Resin composition for fiber-reinforced plastic, cured product of same, and fiber-reinforced plastic comprising said cured product
The present invention provides a resin composition for a fiber-reinforced plastic, the resin composition including a cyanate ester (A), an epoxy resin (B), and an aromatic amine-based curing agent that is liquid at 25° C. (C), wherein the average number of cyanate groups in the cyanate ester (A) is 2.1 or greater, and/or the average number of epoxy groups in the epoxy resin (B) is 2.1 or greater. A fiber-reinforced plastic that is produced using this composition and a reinforcing fiber has favorable heat resistance and excellent tensile and bending properties, and therefore can be applied to a wide variety of fields including transport vehicles such as ships, automobiles, and aircrafts, sporting goods, building materials such as sinks and window frames, as well as industrial machinery and materials such as high-pressure gas tanks and blades for wind power generation.
1. A resin composition for a fiber-reinforced plastic, the resin composition comprising:
at least one cyanate ester (A), at least one epoxy resin (B), and at least one aromatic amine-based curing agent that is liquid at 25° C. (C),
wherein (B) contains at least one multifunctional epoxy resin selected from the group consisting of N,N-bis(2,3-epoxypropyl)-4-(2,3-epoxypropoxy)-2-methylaniline, N,N-bis(2,3-epoxypropyl)-4-(2,3-epoxypropoxy)aniline, and N,N,N′,N′-tetra(2,3-epoxypropyl)-4,4′-diaminodiphenylmethane;
wherein (A) is present in an amount of 10 to 200 parts by mass per 100 parts by mass of (B);
wherein (C) is present in an amount of 20 to 100 parts by mass per 100 parts by mass of (B);
wherein an average number of cyanate groups in the cyanate ester (A) expressed as a formula (1) below is 2, and an average number of epoxy groups in the epoxy resin (B) expressed as a formula (2) below is 2.5 to 4:
Average
number
of
cyanate
groups
=
∑
i
=
1
n
(
A
i
×
X
i
)
100
(
1
)
wherein, in the formula (1), “n” represents the number of types of cyanate ester components contained in the cyanate ester (A), A i represents the number of cyanate groups in an i-th cyanate ester component contained in the cyanate ester (A), and X i represents the content ratio by mass of the i-th cyanate ester component in the cyanate ester (A), and
Average
number
of
epoxy
groups
=
∑
k
=
1
n
(
B
k
×
Y
k
)
100
(
2
)
wherein, in the formula (2), “n” represents the number of types of epoxy resin components contained in the epoxy resin (B), B k represents the number of epoxy groups in a k-th epoxy resin component contained in the epoxy resin (B), and Y k represents the content ratio by mass of the k-th epoxy resin component in the epoxy resin (B).
2. The resin composition for a fiber-reinforced plastic as set forth in claim 1 , wherein (A) contains at least one of a compound represented by a general formula (3-1) below and a prepolymer of the compound represented by the general formula (3-1) below:
NCO—R b —R a —R c —OCN (3-1)
wherein, in the general formula (3-1), R a represents a single bond, —S—, or a divalent hydrocarbon group, and R b and R c each independently represent a phenylene group that is unsubstituted or substituted with 1 to 4 alkyl groups, and
when R b and R c are substituted with 2 to 4 alkyl groups, the alkyl groups may be the same or different.
3. The resin composition for a fiber-reinforced plastic as set forth in claim 2 , wherein the compound represented by the general formula (3-1) is a compound represented by a general formula (3-3) below:
wherein, in the general formula (3-3), R c represents a single bond, a methylene group, —CH(CH 3 )—, —C(CH 3 ) 2 —, or any one of functional groups represented by general formulae (4-1) to (4-8) below, and
R f , R g , R h , and R i each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
wherein, in the general formula (4-3), “m” represents an integer of 4 to 12, and
in the general formulae (4-1) to (4-8), “*” represents a bond.
4. The resin composition for a fiber-reinforced plastic as set forth in claim 3 , wherein (C) is at least one compound selected from the group consisting of diaminodiphenylmethane, diaminodiethyldiphenylmethane, and diaminodiethyltoluene.
5. A cured product which is obtained by curing the resin composition for a fiber-reinforced plastic as set forth in claim 3 .
6. A fiber-reinforced plastic which is obtained by curing a composition containing the resin composition as set forth in claim 3 and a reinforcing fiber.
7. The resin composition for a fiber-reinforced plastic as set forth in claim 2 , wherein (C) is at least one compound selected from the group consisting of diaminodiphenylmethane, diaminodiethyldiphenylmethane, and diaminodiethyltoluene.
8. A cured product which is obtained by curing the resin composition for a fiber-reinforced plastic as set forth in claim 2 .
9. A fiber-reinforced plastic which is obtained by curing a composition containing the resin composition as set forth in claim 2 and a reinforcing fiber.
10. The resin composition for a fiber-reinforced plastic as set forth in claim 1 , wherein (C) is at least one compound selected from the group consisting of diaminodiphenylmethane, diaminodiethyldiphenylmethane, and diaminodiethyltoluene.
11. A cured product which is obtained by curing the resin composition for a fiber-reinforced plastic as set forth in claim 10 .
12. A cured product which is obtained by curing the resin composition for a fiber-reinforced plastic as set forth in claim 1 .
13. A fiber-reinforced plastic which is obtained by curing a composition containing the resin composition as set forth in claim 1 and a reinforcing fiber.