GB551878A - Improved resinous moulding compositions - Google Patents

Abstract

551,878. Moulding compositions. DU PONT DE NEMOURS & CO., E. I. July 23, 1941, No. 14180/42. Convention date, July 23, 1940. Divided out of 550,871. [Class 2 (iii)] Lubricated moulding compositions are produced by dispersing one or more ethenoid monomers (i.e. containing the group CH2 2 = C<), in water containing a dispersing agent, initiating polymerization and adding during " the peak period of the polymerization " one or more di- or tri-esters of phosphoric acid with saturated aliphatic alcohols containing from 12 to 18 carbon atoms inclusive. The preferred proportions of ester are up to 2 per cent. by weight of the monomer(s) and it is preferred to use the disubstituted esters, e.g. dilauryl phosphate. " The peak period of polymerization during the process of dispersion polymerization is the time during which the temperature of the reaction mix rises abruptly to a maximum and drops just as rapidly to its initial level. Specified ethenoid monomers are methyl methacrylate, vinyl acetate and other esters, styrene and its derivatives and other esters of acrylic and methacrylic acids. These monomers may be used alone or as mixtures. Plasticizers may be added to the polymerization reaction and the granular polymer' may be compounded with auxiliary ingredients, i.e. colours. In examples the aqueous vehicle contains mono- and disodium phosphates and a partially neutralized polymethacrylic acid solution as granulating agent. Monomeric methyl methacrylate alone in (1) or with vinyl acetate (2), styrene (3), is polymerized in dispersion with benzoyl peroxide and at " the peak period " dilauryl phosphate (dimyristyl phosphate in (2) and distearyl phosphate in (3) ) is added.