ADHESION TO METAL SURFACES WITH BLOCK COPOLYMERS OBTAINED USING RAFT

摘要

An aqueous, metal, coating composition (and process for obtaining it) comprising a block copolymer and a polymer P; wherein the block copolymer comprises at least blocks [A]x[B]y, where at least block [A] is obtained by a controlled radical polymerisation of at least one ethylenically unsaturated monomer via a reversible addition-fragmentation chain transfer (RAFT) mechanism in solution in the presence of a control agent and a source of free radicals; and where (a) block [A] comprises (i) 0 to 80 mol% of metal adhering ethylenically unsaturated monomers; (ii) 0 to 100 mol % of water dispersible ethylenically unsaturated monomers; (iii) 0 to 70 mol % of C1 to C30 hydrocarbo (meth)acrylate and/or styrenic monomers; (iv) 0 to 35 mol % of ethylenically unsaturated monomer different from i), ii) + iii); where the amount of at least one of i), ii), iii) + iv) is > 0 mol%; block [A] has a Hansch parameter < 1.5; and an average degree of polymerisation x, (x = 3 to 80); (b) block [B] comprises: i) 0 to 50 mol% of metal adhering ethylenically unsaturated monomers; ii) 0 to 15 mol % of water dispersible ethylenically unsaturated monomers; iii) 20 to 100 mol % of C1 to C30 hydrocarbo (meth)acrylate and/or styrenic monomers; iv) 0 to 35 mol % of ethylenically unsaturated monomers units different from those from i), ii) + iii); where block [B] has a Hansch parameter = 1.5; and block [B] an average degree of polymerisation y (y = 10 and > x); and (c) polymer P is obtained by an emulsion polymerisation process in the presence of the block copolymer [A][B] and comprises: i) 0 to 5 wt % of metal adhering ethylenically unsaturated monomers; ii) 0 to 15 wt% of water dispersible ethylenically unsaturated monomers; iii) 50 to 100 wt % C1 to C30 hydrocarbo (meth)acrylate and/or styrenic monomers; and iv) 0 to 35 % by weight of ethylenically unsaturated monomers units different from those from i), ii) + iii).