Epoxy resin, epoxy resin composition, epoxy resin cured product, and composite material

1. An epoxy resin composition, comprising:

an epoxy resin comprising:

an epoxy compound A that has at least two mesogenic structures and at least one phenylene group,

an epoxy compound B that has at least two mesogenic structures and at least one divalent biphenyl group, wherein the ratio between epoxy compound A and epoxy compound B (epoxy compound A:epoxy compound B) is from 3:7 to 9:1; and

a curing agent selected from the group consisting of 3,3′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylether, 4,4′-diamino-3,3′-dimethoxybiphenyl, 4,4′-diaminophenylbenzoate, 1,5-diaminonaphthalene, 1,3-diaminonaphthalene, 1,4-diaminonaphthalene, 1,8-diaminonaphthalene, 1,3-diaminobenzene, 1,4-diaminobenzene, 4,4′-diaminobenzanilide, trimethylene-bis-4-aminobenzoate, phenol, o-cresol, m-cresol, p-cresol, catechol, resorcinol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene, and 1,3,5-trihydroxybenzene.

2. The epoxy resin according to claim 1 , wherein at least one of the epoxy compound A or the epoxy compound B has a structure in which the phenylene group or the divalent biphenyl group is disposed between the at least two mesogenic structures.

3. The epoxy resin according to claim 1 , wherein at least one of the at least two mesogenic structures of at least one of the epoxy compound A or the epoxy compound B has a structure represented by the following Formula (3):

wherein, in Formula (3), each of R 3 to R 6 independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

4. The epoxy resin composition according to claim 1 , being configured to form a smectic structure in a cured state.

5. An epoxy resin cured product comprising a cured product of the epoxy resin composition according to claim 1 .

6. A reinforcing material, comprising the epoxy resin cured product according to claim 5 and a reinforcing material.