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

1. An epoxy resin comprising an epoxy compound present in an amount of up to 50% by mass of a total of the epoxy resin, the epoxy compound comprising two structures represented by the following Formula (I) and at least one divalent biphenyl group:

wherein, in Formula (I), each of R 1 to R 4 independently represents a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms.

2. The epoxy resin according to claim 1 , wherein the epoxy compound has a structure in which one of the at least one divalent biphenyl groups is positioned between two structures represented by Formula (I).

3. The epoxy resin according to claim 1 , wherein the epoxy compound comprises at least one selected from the group consisting of a structure represented by the following Formulae (II-A) and a structure represented by the following (II-B):

wherein, in Formula (II-A) and Formula (II-B), each of R 1 to R 4 independently represents a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms, each of R 5 and R 6 independently represents an alkyl group having from 1 to 8 carbon atoms, each of n and m independently represents an integer from 0 to 4, and each X independently represents —O— or —NH—.

4. The epoxy resin according to claim 1 , wherein the epoxy compound is present in an amount of 10% to 50% by mass of a total of the epoxy resin.

5. An epoxy resin composition, comprising the epoxy resin according to claim 1 and a curing agent.

6. The epoxy resin composition according to claim 5 , which is configured to form a smectic structure in a cured state.

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

8. A composite material, comprising the epoxy resin cured product according to claim 7 and a reinforcing material.