(meth)acrylic ester copolymer and curable composition containing the same

A (meth)acrylic ester copolymer (B) comprising a reactive silicon group represented by the following formula (1):

• —SiR5cX3-c (1), wherein R5 is a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, X is a hydroxy group or a hydrolyzable group, and c is 0 or 1, wherein:
• the copolymer (B) comprises a structure in which two first molecular chains are bonded to each other via one second molecular chain,
• both ends of the second molecular chain are bonded to a non-terminal moiety of one of the first molecular chains and a non-terminal moiety of the other first molecular chain, respectively,
• each of the first and second molecular chains comprises a molecular chain of a (meth)acrylic ester copolymer,
• the reactive silicon group is bonded to each of the first molecular chains, and
• each of the first molecular chains has, at either end thereof, a structure represented by —S—R, wherein S is a sulfur atom and R is a hydrocarbon group optionally having the reactive silicon group.

A method of producing a (meth)acrylic ester copolymer (B) comprising:

• copolymerizing a monomer component,
• wherein:
• the monomer component comprises:
• a (meth)acrylic ester (b1);
• a (meth)acrylic ester polymer (b2) having more than one (meth)acryloyl groups per molecule;
• and
• a chain transfer agent (b3) having a mercapto group,
• the monomer component further comprises a monomer (b4) having a reactive silicon group and a polymerizable unsaturated group, and/or the chain transfer agent (b3) having a mercapto group further has a reactive silicon group, and
• the (meth)acrylic ester copolymer (B) has a reactive silicon group represented by the following formula (1):
• —SiR5cX3-c (1), wherein R5 is a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, X is a hydroxy group or a hydrolyzable group, and c is 0 or 1.