Improvements in or relating to halogenated polythenes

Abstract

Abstract 545,500. Halogenated ethylene polymers. WHITTAKER, D., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. Sept. 27, 1940, Nos. 14659/40 and 12498/41. [Class 2 (iii)]. Halogenated ethylene polymers are rendered heat-stable by the incorporation therein of a small proportion of an oxide or hydroxide of a metal of Groups II ,III or IV of the Periodic classification. or a salt in which the acid of the acidic radical has a lower dissociation constant than the base of the basic radical, compounds containing chromium, manganese, iron, cobalt, nickel, copper, zinc and -silver being .excluded, and oxidizing agents being also excluded. Acids from which the salts may be derived include acetic, lactic, tartaric, benzeic omethylol benzoic, salicylic, phosphoric, naphthalic and phthalic acids. Suitable salts include those of sodium, potassium, magnesium, calcium, strontium, barium, aluminium and lead with carbonic, ricinoleic, oleic, maleic, malonic, chloracetic and carbonic acids, and with acids derived from the oxides of selenium, arsenic, silicon, tin and boron. Preferred salts are lead carbonate, and sodium, potassium and lead salts of acids whose first (or only) dissociation constant lies within the range 1 x 10<SP>-5</SP> and 125 x 10-<SP>5</SP> since such salts, in addition to suppressing hydrogen halide evolution, also inhibit colour darkening of the halogenated polymers when heated. The stabilizer may be incorporated with tne polymer by (a) mixing or grinding togetber the powdered substances, (b) mixing the powdered stabilizer on heated rolls with the softened polymer, or (c) dissolving, dispersing or suspending the finely divided stabilizer in a solution of the polymer, the solution being then either used as such, e.g. as a varnish, or coating agent or for casting in a mould, or the'stabilized polymer being obtained by removal of the solvent or by precipitation. The stabilizers may be used in conjunction with the light stabilizers described in Specification 538,871. Stabilizers specified in the examples are magnesium oxide, lead hydroxide, carbonate, tartrate, and phthalate, potassium borate, and sodium acetate, lactate, tartrate, benzoate, o-methylol benzoate, salicylate, naphthalate, phthalate, ricinoleate and phosphates. Specifications 471,590, 481,515 and 519,422 also are referred to.

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