GB518970A - Manufacture of polymerisation products derived from acrylic acid derivatives - Google Patents

Abstract

518,970. Polymerization products ; polymeriziable compounds. CRAWFORD, J. W. C., McLEISH,. N., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. Sept. 5, 1938, Nos. 25954/38 and 7683/39, [Class 2 (iii)] Polymers of alpha-chloroacrylic acid or its esters having relatively little colour are obtained by treating the monomeric compounds to free them from autoxidation products and thereafter subjecting them, while substantially free from such products, to polymerization, preferably in' the absence of atmospheric oxygen. The polymerization may be effected in the presence of one or more additional polymerizable compounds or in the presence of non-polymerizable compounds, e.g. angelic or tiglic acid, capable of forming interpolymers with polymerizable alpha-#- unsaturated compounds. Plasticizers, softeners, fillers and other modifiers may be present during the polymerization. The removal of the autoxidation products may be effected by distillation in the substantial absence of oxygen, e.g. in vacuo or in an atmosphere of nitrogen, or the monomeric compounds may be treated with a reagent whereby the autoxidation products are destroyed. Preferably the two processes are combined. Suitable reagents are reducing agents, hydrogen peroxide, perborates or other per-compounds, or compounds such as potassium permanganate, having a labile oxygen atom. Preferably this treatment is followed by treatment with an alkaline reacting compound, e.g. a water-soluble carbonate, bicarbonate or borate or an alkali metal hydroxide. In examples : (1) methyl alpha-chloroacrylate is treated with (a) sodium carbonate and hydrogen peroxide solutions, (b) sulphur dioxide solution, (c) phenyl hydrazine solution, (d) sodium carbonate solution containing hydrogen peroxide, (e) sodium carbonate solution containing sodium hydrosulphite, (f) sodium persulphate solution, (g) sodium perborate solution, and (h) sodium hypochlorite solution, and the treated ester is polymerized in the presence of benzoyl peroxide; (2) methyl alpha-chloroacrylate is distilled in an atmosphere of nitrogen under reduced pressure and polymerized in the presence of benzoyl peroxide ; (3) n-propyl- or isopropyl-alpha-chloroacrylate is distilled under reduced pressure and treated with an aqueous solution containing sodium hydrosulphite and sodium carbonate and then polymerized in the presence of benzoyl peroxide. Adequately purified acid or esters give no colour with phenylhydrazine and aqueous ferricyanide, and no colour with aqueous pyridine. The purified esters are neutral.