Patent ID: 8680180

Claim:
An epoxy resin composition comprising an epoxy resin (A) and rubber-like polymer particles (B), in which the rubber-like polymer particles (B), maintain a finely dispersed state of primary particles and the content of the rubber-like polymer particles (B) is 0.5 to 80% by weight when the total amount of the epoxy resin (A) and rubber-like polymer particles (B) is 100% by weight, wherein: the rubber-like polymer particles (B) are obtainable by graft-polymerizing 5 to 50% by weight of a shell layer (B-2) with 50 to 95% by weight of a rubber particle core (B-1) in the presence of an emulsifier, and average particle diameter of the rubber-like polymer particles (B) is 0.03 to 2 μm; and the rubber particle core (B-1) comprises elastic material composed of not less than 50% by weight of at least one monomer selected from the group consisting of diene monomers and (meth)acrylate monomers and less than 50% by weight of another coploymerizable vinyl monomer, or polysiloxane rubber elastic materials, or a mixture thereof; and the shell layer (B-2) comprises at least one monomer selected from the group consisting of (meth)acrylates, aromatic vinyls, vinyl cyanides, unsaturated acid derivatives, (meth)acrylamide derivatives and maleimide derivatives; and the finely dispersed state of primary particles means that the particle dispersion ratio calculated according to the following equation is not less than 90%: particle dispersion ratio (%)=(1−B1/B0))×100, wherein B1 is the number of the rubber-like polymer particles (B) in the form where three or more polymer particles are contacted with one another, and B0 is the total number of rubber-like polymer particles (B) and the epoxy resin composition comprises the emulsifier in an amount of not more than 0.15% by weight.