To obtain a (co)polymer which is practically re-emulsifiable in water at a pH is 5 or higher by selecting a (co)polymer having repeating units having specific pendant groups.
This (co)polymer has a core/shell structure wherein the surface of the core is at least partly covered with the shell. The core is formed from a copolymer (A) which has lower than 40wt.% repeating units selected from among repeating units having pendant groups represented by formula I (wherein R1 and R2 are each H or an optionally hydroxylated 1-12C alkyl group) and repeating units having pendant groups represented by formula II [wherein R3 is a 1-30C alkylene, or -R3OH is -(R22O)nH (wherein R22 is a 2-5C alkylene; and n is 2-30)]. The shell is formed from a (co)polymer (B) having 20-100wt.% such repeating units as described above. The wt. ratio of (co)polymer A to (co)polymer B is (85/15)-(15/85), and the content of the above-described repeating units in (co)polymer B is higher than that of (co)polymer A.
MATSUMOTO KATSUNARI
HOSHINO FUTOSHI
KIKUTA YOSHIO
