Aqueous suspension polymerization in the presence of methyl hydroxypropyl cellulose as granulating agent

摘要

A non-emulsified aqueous suspension of monomeric vinylidene chloride, vinyl chloride or acrylonitrile or mixtures of monomeric vinylidene chloride with vinyl chloride or with acrylonitrile, in a closed system to prevent loss of monomer vapour, is polymerized in the presence of from 0.2 to 1 per cent, based on the weight of monomer, of a catalyst consisting of 2,4-dichlorobenzoyl peroxide or lauroyl peroxide and from 0.1 to 5 per cent, based on the weight of monomer, of low viscosity methyl hydroxypropyl cellulose having a methoxyl content of from 25 to 32 per cent and containing from 0.05 to 0.2 hydroxypropyl groups per C6H10O5 unit, the weight ratio of water to monomers being from 1 : 1 to 4 : 1, and the dispersion of polymerizing particles being maintained by agitation at a temperature from 25 DEG to 65 DEG C. until at least 70 per cent polymerization has occurred. The cellulose derivative employed may be made by the reaction between alkali cellulose and a mixture of a relatively large amount of methyl chloride and a much smaller amount of propylene oxide.