PREPARATION OF AN IMPACT-RESISTANT POLYACRYLATE/VINYL CHLORIDE GRAFT COPOLYMER

摘要

A new process far preparing a thermoplastic material based on vinyl chloride homo- or copolymers and polyacrylates is disclosed. The process comprises adding a polyacrylate latex to an aqueous suspension of vinyl chloride or vinyl chloride with a copolymerizable monomer, in the presence of an initiator and a suspending agent, at a temperature of at least 30.degree. and polymerizing vinyl chloride onto the polyacrylate at a temperature greeter than 30.degree.C. The polyacrylate latex is prepared by polymerizing in an aqueous emulsion an acrylate or a mixture of acrylates having a polymer glass transition temperature of less thaw -20.degree.C, in the presence of a copolymerizable crosslinking compound having at least two nonconjugated double bonds. Compared with process known in the prior art, the process of the invention produces polymer particles having narrower particle size distribution and more reproducible bulk density. The caking on the reactor walls during the polymerization process is also substantially reduced. The mouldings obtained from the polymers prepared by the process of the invention are characterized by good processibility, high impact strength and good surface quality.