Curable composition and cured product thereof

An electrically insulating material comprising a cured product of a composition,

• wherein the composition comprises:
• an olefin-aromatic vinyl compound-aromatic polyene copolymer satisfying the following conditions (1) to (4);
• and
• an additive resin that is one or more selected from the group consisting of a hydrocarbon-based elastomer, an olefin-aromatic vinyl compound-aromatic polyene copolymerized oligomer, and an aromatic polyene-based resin, wherein the hydrocarbon-based elastomer is one or more selected from the group consisting of ethylene-based elastomer, propylene-based elastomer, 1,2-polybutadiene, and hydrides thereof, wherein the 1,2-polybutadiene is liquid at 25° C., and
• wherein the electrically insulating material has a storage elastic modulus at 300° C. of 5×105 Pa or more, and a dielectric constant of 2.5 or less and 2.0 or more and a dielectric tangent of 0.003 or less and 0.0005 or more at 23° C. and 10 GHz:
• (1) a number average molecular weight of the copolymer is 5000 or more and 100000 or less;
• (2) the aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and the content of the aromatic vinyl compound monomer unit is 0 mass % or more and 70 mass % or less;
• (3) the aromatic polyene is one or more selected from polyenes having 5 or more and 20 or less carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and a content of the vinyl groups and/or the vinylene groups derived from a unit of the aromatic polyene is 1.5 pieces or more and less than 20 pieces per number average molecular weight;
• and
• (4) the olefin is one or more selected from olefins having 2 or more and 20 or less carbon atoms, and a total of units of the olefin monomer, the aromatic vinyl compound monomer, and the aromatic polyene monomer is 100 mass %.