An epoxy resin composition for a cured material, comprising (A) an epoxy
resin comprising an epoxy compound X, the epoxy compound X has an epoxy
equivalent weight of at least 400, (B) a curing agent, and (C) a liquid
rubber that is liquid at room temperature and comprises a reactive group;
wherein the epoxy compound X has a solubility parameter value of SpX, the
liquid rubber has a solubility parameter value of SpY and the ratio of
SpY/SpX could be in the range of 0.7 to 1.3; and wherein the liquid
rubber could form no visible domains by optical microscopy or has a
maximum domain size of at most 3 microns in the cured material is
described. The epoxy resin composition provides a fiber-reinforced
material with higher compressive modulus and strength, toughness and
better handling ability over standard epoxy resin systems. This invention
is excellent for small thin walled tube structures like fishing rods or
applications that require good compressive strength.