Epoxy resin composition, prepreg, and carbon fiber reinforced composite material

An epoxy resin composition comprising components [A] to [D],

• the component [A] accounting for 5 to 30 parts by mass,
• the component [B] accounting for 20 to 95 parts by mass, and
• the component [C] accounting for 1 to 25 parts by mass, relative to the total quantity of the epoxy resins which account for 100 parts by mass, and
• an 80° C. viscosity measured at an angular frequency of 3.14 rad/s is in the range of 5 to 100 Pa·s
• [A]:
• epoxy resin having one or more condensed polycyclic aromatic hydrocarbon backbones and mainly two epoxy groups in a repeating unit as represented by general formula [1] or [4],
• wherein:
• X in general formulae [1] and [4] is an alkylene group containing 1 or 2 carbon atoms or a group as represented by general formula [2];
• R in general formula [2] is one selected from the group consisting of a glycidyl ether group, a group as represented by general formula [3], a hydrogen atom, a halogen atom, a phenyl group, and an alkyl group containing 1 to 4 carbon atoms;
• Y is an aromatic ring or a condensed polycyclic aromatic hydrocarbon;
• Z is a condensed polycyclic aromatic hydrocarbon;
• n is 1 or greater;
• Y and Z each have a glycidyl ether group, or either Y or Z has a substituent group as represented by general formula [3], and each repeating unit mainly contains two epoxy groups;
• the aromatic ring and condensed polycyclic aromatic ring in Y or Z may be bonded to the backbone chain at the ortho position or the meta position;
• and
• T is a polycyclic aromatic hydrocarbon or a hydrogen atom;
• [B]:
• a glycidyl amine type epoxy resin having three or more glycidyl groups in a molecule;
• [C]:
• sulfone based or imide based thermoplastic resin;
• and
• [D]:
• epoxy resin curing agent.