To provide a copolymer latex having good stickiness which causes smearing during operation, and excellent adhesive strengths.
The method for producing the copolymer latex for paper coating is, in a copolymer latex prepared by polymerizing an aliphatic conjugate diene, an ethylene-based unsaturated carboxylic acid monomer and another copolymerizable monomer, to perform polymerization by adding the monomer separately in 2 steps so that a theoretical Tg derived by the Fox equation from the Tg of a homopolymer of the monomer added in each step is in a range of -30 to 30C in a copolymer composition of the first step, and adding the monomer to have 10C difference in a copolymer composition after the second step in comparison with the theoretical Tg of the proceeding step. The obtained latex has one glass transition temperature (Tg) of the prepared latex measured by a differential scanning calorimeter, and the difference between T1 and T2 in the endothermic reaction in a chart is 20C.
HOSOYA TAKASHI
NAKAJIMA YURIE
Next Patent: SELF-ADHESIVE FILM FOR SURFACE PROTECTION