Abstract: It is an object of the present invention to provide (1) a copolymer for a cured product that is satisfactory in properties, such as adhesion properties, as a chip stacking adhesive or the like. The present invention is a copolymer comprising repeating units represented by formula (I), formula (II), and formula (III), (wherein R1, R2, and R3 each independently represent a hydrogen atom or a methyl group, R4 represents an alkyl group or a cycloalkyl group, R5 represents a hydrogen atom or a C1 to C6 alkyl group, m, n, and k represent a molar ratio of the respective repeating units, m represents a positive number of 0 or more and less than 1, n and k each independently represent a positive number, and satisfy a relation of m+n+k=1), and having a weight-average molecular weight in the range of 50,000 to 200,000.

Abstract: It is an object of the present invention to provide (1) a copolymer for a cured product that is satisfactory in properties, such as adhesion properties, as a chip stacking adhesive or the like. The present invention is a copolymer comprising repeating units represented by formula (I), formula (II), and formula (III), (wherein R1, R2, and R3 each independently represent a hydrogen atom or a methyl group, R4 represents an alkyl group or a cycloalkyl group, R5 represents a hydrogen atom or a C1 to C6 alkyl group, m, n, and k represent a molar ratio of the respective repeating units, m represents a positive number of 0 or more and less than 1, n and k each independently represent a positive number, and satisfy a relation of m+n+k=1), and having a weight-average molecular weight in the range of 50,000 to 200,000.

Abstract: Disclosed is a star polymer having a core part produced by anionic polymerizing one or more polyfunctional (meth)acrylic acid ester derivative represented by formula (IV) (wherein R represents a hydrogen atom, etc., n represents 2 or 3, and A represents an organic group linking at a carbon atom) in an organic solvent, in the presence of 0.1 to 0.99 mol of organic alkali metal compound with respect to 1 mol of the compound of the formula (IV), and in the presence of 0.1 to 20 mol of inorganic salts of alkali metal or alkali earth metal with respect to 1 mol of the organic alkali metal compound, and an arm part formed by anionic polymerizing from the anionic active site of the core part one or more monofunctional (meth)acrylic acid ester derivative represented by formula (I) (wherein R1 represents a hydrogen atom, etc., and R2 represents an organic group).