Patent ID: 7314899

Claim:
A process for preparation of a dispersion of a self dispersing, synergistic poly(urethane-co-acrylic) copolymer useful as coating material, said process comprising the steps of: a. treating a polyol, having molecular weight in the range of 500-3000, with 150-200 mole % of a (cyclo)aliphatic or aromatic isocyanate at a temperature in the range of 40-150° C. under a nitrogen atmosphere, for a period of minimum 2 hours to obtain an isocyanate terminated pre-polymer; b. adding 50-100 mole %, based on the (cyclo)aliphatic or aromatic isocyanate, of an iniferter and 0.1-0.3 mol % of catalyst to the isocyanate terminated pre-polymer, in an organic solvent, under agitation at a temperature not exceeding 40° C. for a period in the range of 15-30 hrs to obtain an iniferter incorporated polyurethane; c. treating 25-400% w/w of a vinyl monomer selected from the group consisting of vinyl monomers containing carboxyl groups or sulfonic acid groups, with the iniferter incorporated polyurethane for a minimum of 12 hours at a temperature in the range of 50-80° C. to obtain a urethane-co-acrylic polymer; d. adding 0.01-0.1 mole % of base to the urethane-co-acrylic polymer, formed in step (c), under agitation at a temperature in the range of 30-80° C. for a period of minimum 1 hour to obtain a slurry, and e. dispersing the slurry in 150-200% v/v of water to obtain the dispersion of the poly(urethane-co-acrylic) copolymer.