Water borne crosslinkable block copolymers obtained using raft

Abstract

There is disclosed a process for obtaining a water-borne crosslinkable composition comprising a block copolymer comprising at least blocks [A] x [B] y (where x is an integer from 3 to 80 (inc.), where y is an integer ≧10 and where y>x) and a polymer P, the block copolymer-polymer having an acid value ≦150 mg KOH per g of block copolymer-polymer, where at least block [A] and [B] 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 polymer P is obtained in the presence of blocks [A] x [B] y by an emulsion polymerisation process.

1 . A process for obtaining a water-borne non-biologically active crosslinkable composition comprising a block copolymer comprising at least blocks [A] x [B] y  and a polymer P, the block copolymer-polymer composition having an acid value <150 mg KOH per g of block copolymer-polymer, where at least block [A] and [B] 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;
 where block [A] comprises:   i) 0 to 50 mol % of ethylenically unsaturated monomer units bearing crosslinking functional groups;   ii) 50 to 100 mol % ethylenically unsaturated monomer units bearing water-dispersing functional groups;   iii) 0 to 50 mol % of ethylenically unsaturated monomers units selected from C 1-18  alkyl(meth)acrylate monomers and styrenic monomers;   iv) 0 to 35 mol % of ethylenically unsaturated monomers units different from those from i), ii) iii);   where i), ii), iii)+iv) add up to 100%;   block [A] has a Hansch parameter <1.5; and   block [A] has an average degree of polymerisation x, where x is an integer from 3 to 80;   where block [B] comprises:   i) 5 to 80 mol % of ethylenically unsaturated monomer units bearing crosslinking functional groups;   ii) 0 to 20 mol % of ethylenically unsaturated monomer units bearing water-dispersing functional groups;   iii) 20 to 95 mol % of ethylenically unsaturated monomers units selected from C 1-18  alkyl(meth)acrylate monomers and styrenic monomers;   iv) 0 to 35 mol % of ethylenically unsaturated monomers units different from those from i), ii)   where i), ii), iii)+iv) add up to 100%;   block [B] has a Hansch parameter >1.5; and   block [B] has an average degree of polymerisation y, where y is an integer >10, where y>x; and   where the polymer P is obtained in the presence of the block copolymer by an emulsion polymerization process; and comprises:   i) 0 to 5 wt % of ethylenically unsaturated monomer units bearing crosslinking functional groups;   ii) 0 to 5 wt % of ethylenically unsaturated monomer units bearing water-dispersing functional groups;   iii) 80 to 100 wt % of ethylenically unsaturated monomers units selected from C 1-18  alkyl(meth)acrylate monomers and styrenic monomers;   iv) 0 to 10 wt % of ethylenically unsaturated monomers units different from those from 1), ii) iii);   where i), ii), iii)+iv) add up to 100%.   
     
     
         2 . A process according to  claim 1  where:
 block [A] comprises: 
 (i) 0 to 20 mol % of ethylenically unsaturated monomer units bearing crosslinking functional groups; 
 iii) 0 to 50 mol % of ethylenically unsaturated monomers units selected from C 1-12 alkyl (meth)acrylate monomers and styrenic monomers; and 
 iv) 0 to 20 mol %, of ethylenically unsaturated monomers units different from those from i), ii) iii); 
 block [B] comprises: 
 iii) 20 to 95 mol % of ethylenically unsaturated monomers units selected from C 1-12  alkyl(meth)acrylate monomers and styrenic monomers; and 
 iv) 0 to 20 mol % of ethylenically unsaturated monomers units different from those from i), ii) iii); and 
 the polymer P comprises: 
 iii) 80 to 100 wt % of ethylenically unsaturated monomers units selected C 1-12 alkyl(meth)acrylate monomers and styrenic monomers. 
 
     
     
         3 . A process according to  claim 1 , where the number average molecular weight of the block copolymer is in the range of from 1,000 to 50,000 g/mol. 
     
     
         4 . A process according to  claim 1 , where the weight average molecular weight of the polymer P is >50,000 g/mol. 
     
     
         5 . A process according to  claim 1 , wherein polymer P is more hydrophobic than block [A]. 
     
     
         6 . A process according to  claim 1 , wherein the wt % of blocks [A][B] together is in the range of from 0.5 to 50% based on the weight of blocks [A][B] and polymer P. 
     
     
         7 . A process according to  claim 1 , where at least 20 wt % of polymer P is covalently bonded to the block copolymer. 
     
     
         8 . A process according to  claim 1 , wherein the control agent is selected from the group consisting of dithioesters, thioethers-thiones, trithiocarbonates, dithiocarbamates, xanthates and mixtures thereof. 
     
     
         9 . A polymeric composition obtained and/or obtainable by the process claimed in  claim 1 . 
     
     
         10 . A water-borne composition comprising the block copolymer-polymer prepared or a polymeric composition of  claim 9 , additionally comprising a separate crosslinking agent. 
     
     
         11 . An ink, paint or adhesive comprising the block-copolymer-polymer or a polymeric composition of  claim 9 . 
     
     
         12 . Use of a formulation comprising the block copolymer-polymer prepared or a polymeric composition of  claim 9 , to coat a substrate.