Process for providing homogeneous copolymers of vinylpyrrolidone and vinyl acetate which form clear aqueous solutions having a high cloud point
AssigneeISP Investments Inc.
InventorsYuanzhen Zhong, Hemant Parikh, Terry E. Smith
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Abstract
A process for making homogeneous copolymers of vinylpyrrolidone (VP) and vinyl acetate (VA) which form clear aqueous solutions and have high cloud points. The process involves precharging VP and VA monomers in a predetermined ratio, and then feeding VP and VA at a predetermined rate, the ratio of the components in the initial charge and the feeding rates for the monomer being selected in accordance with the reactivity rates of the monomers towards copolymerization as opposed to homopolymerization.
Claims11
A process for making substantially homogeneous copolymers of vinylpyrrolidone and vinyl acetate which form clear aqueous solutions having a high cloud point substantially in excess of room temperature by polymerization of the monomers in a water miscible organic solvent in the presence of a radical initiator, which comprises:
- (a) precharging a reactor with predetermined initial amounts of vinylpyrrolidone and vinyl acetate monomers to provide a selected weight ratio of monomers, solvent and initiator, at a polymerization temperature, and
- (b) introducing separate feed streams of vinylpyrrolidone and vinyl acetate monomers, solvent and initiator into said reactor at predetermined rates, over a given period of time.
Dependencies are inferred from the claim text.