Continuous high press. dispersion (co)polymerisation of ethylene - with short residence time, by controlling rate of addn. of monomer(s) and aq. phase

摘要

Aq. dispersions of ethylene (co)polymers are prepd. by charging to the polymeriser (A) ethylene or a mixt. contg is not 50 moles % ethylene and 1-50% of a comonomer, in amt. of 4-24 kg/hr./dm3 of polymerisation space, and (B) 1-6 kg/hr./dm3 of polymerisation space, of water contg. in soln. (a) 0.001-0.1 of a polymerisation initiator/kg water, and (b) 0.001-0.05 kg of a stable emulsifier/kg water, where (c) the pH of the water is 4.5-12 (6.5-12), and polymerising at 400-2000 (800-2000) bars and 100-200 degrees C (130-170 degrees C), with stirring. Fine dispersions are obtd. in a short residence time, at pH >4, of known processes, in which narrow pH ranges were needed. The amt. of emulsifier is smaller. The dispersions have low viscosity, even at high solids content, are stable on storage for >1 year, and give coherent dry films.