Aqueous coating composition, process for production and use thereof

摘要

Production of copolymers (I), in aqueous dispersion and/or solution form, involves: (i) predosing a mixture of hydroxy-functional hydrophobic copolymer and an organic solvent, heated to the polymerization temperature, with a radical initiator (RI); (ii) dosing in parallel with a specific hydrophobic, (almost) carboxy group-free monomer mixture and RI; and (iii) dosing in parallel with a specific hydrophilic monomer mixture and RI. The copolymers (I) are new. - Production of copolymers (I), in aqueous dispersion and/or solution form, involves: - (1) providing (a) 0-40 wt. % (based on (I)) of a hydroxy-functional hydrophobic copolymer (A1) having acid index less than 10 mg KOH per g (insufficient for dissolution in water) and OH content 0.5-7% (both based on 100% resin), number average molecular weight (Mn) 1500-20000 and organic solvent content 0-60 wt. % (based on (A1)) and (b) 0-15% (based on (A1)) additional organic solvent (A2), the mixture of (A1) and (A2) being heated to the required polymerization temperature before or during formation; - (2) predosing with 5-40% (based on the sum of (B1), (C2) and (D2) (defined subsequently)) of a radical initiator (B1), optionally dissolved in an organic solvent; - (3) dosing in parallel with (a) 40-80% (based on (I)) of a hydrophobic, (almost) carboxy group-free monomer mixture (C1) of (c1) 30-90% (1-18C) alcohol (meth)acrylate, vinyl aromatic compound and/or vinyl ester, (c2) 10-60% hydroxy-functional monomers and (c3) 0-2% acid group containing monomers (the sum of the amounts of (c1), (c2) and (c3) being 100%) and (b) 5-40% (based on the sum of (B1), (C2) and (D2)) of a radical initiator (C2), optionally dissolved in an organic solvent; and - (4) dosing in parallel with (a) 5-50% (based on (I)) of a hydrophilic monomer mixture (D1) of (d1) 10-70% (1-18C) alcohol (meth)acrylate, vinyl aromatic compound and/or vinyl ester, (d2) 10-70% hydroxy-functional monomers and (d3) 5-30% acid group containing monomers (the sum of the amounts of (d1), (d2) and (d3) being 100%) and (b) 5-40% (based on the sum of (B1), (C2) and (D2)) of a radical initiator (D2), optionally dissolved in an organic solvent, the total amount of the initiators (B1), (C2) and (D2) being 0.8-5.0 wt. % based on (I). - Independent claims are included for: - (a) the copolymers (I) obtained by the process as new; and - (b) aqueous coating compositions containing (I) having acid index less than 30 mg KOH per g (as solid resin), optionally other dissolved or dispersed binder components and crosslinkers dispersible or soluble in water or in the aqueous binder dispersion.