GB1334193A - Processes for the polymerisation of ethylenically unsaturated monomers in suspension - Google Patents

Abstract

1334193 Suspension polymerization, novel stabilizers therefor AQUITAINE TOTAL ORGANICO 31 Dec 1971 [31 Dec 1970] 60948/71 Heading C3P A process for suspension polymerizing one or more ethylenic monomers, comprises polymerizing the monomer or monomers in aqueous suspension in the presence of a suspending agent which is an inorganic precipitate obtained by co-precipitating a soluble phosphate using a mixture of soluble salts of at least two metals from Groups IIa and IIb of the Periodic Table (i.e. Be, Mg, Ca, Sr, Ba, Ra, Zn, Cd and Hg), and aluminium and iron. In the co-precipitation there are preferably at least 10 metal ions to 6 phosphate ions. The phosphate is preferably an alkali metal phosphate. Preferred metal salts are the nitrates, halides or acetates. A mixture of Ca and Mg salts is preferably used, the ratio of gram ions of Ca to Mg being between 1 : 10 and 10 : 1. A preferred embodiment is where a soluble carbonate is also coprecipitated, there being preferably 1 gm ion CO 3 <SP>-</SP> to 6 gm ions of phosphate. The precipitate may be prepared in the reaction mixture before polymerization begins, or during polymerization, but before 60% conversion has occurred. The polymerization may be begun in bulk, until between 5 and 40% conversion, and then completed in suspension according to the invention. The polymerization of styrene, styrene and methyl methacrylate, styrene and acrylonitrile, styrene in the presence of polybutadiene, and vinyl chloride, is exemplified using Na 3 PO 4 (with or without Na 2 CO 3 ) as the phosphate, and CaCl 2 and MgCl 2 as the metal salts.