Modified copolymerized polyester resin and water dispersion thereof

A modified copolymerized polyester resin (B) having a structure in which a copolymerized polyester resin (A) has a side chain, and the copolymerized polyester resin (A) contains, as copolymerization components, at least two members selected from the group consisting of:

• a copolymerization component having an alicyclic structure (component x);
• a copolymerization component having six or more continuous methylene groups (component y);
• and an acyclic aliphatic copolymerization component having a tertiary carbon atom and a molecular weight of more than 100 (component z),
• wherein, the component x is at least one monomer raw material selected from the group consisting of 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 1,4-cyclohexanedimethanol, 1,3-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxyethyl)cyclohexane, 1,4-bis(hydroxypropyl)cyclohexane, 1,4-bis(hydroxymethoxy)cyclohexane, 1,4-bis(hydroxyethoxy)cyclohexane, 2,2-bis(4-hydroxymethoxycyclohexyl) propane, 2,2-bis(4-hydroxyethoxycyclohexyl)propane, bis(4-hydroxycyclohexyl) methane, 2,2-bis(4-hydroxycyclohexyl)propane, and 3(4),8(9)-tricyclo [5.2.1.02,6]decanedimethanol, and
• the side chain consists of an unsaturated polyvalent carboxylic acid.