| 摘要 |
Chlorine-containing polymers are heat-stabilized by addition of minor amounts of semicarbazide or a condensation product thereof. After-chlorinated polymers or copolymers of compounds which may contain chlorine are included. Specified examples are polymers of vinyl chloride, vinylidene chloride and chlorotrifluoroethylene and copolymers of these with each other and with vinyl esters, e.g. vinyl acetate, and dialkyl fumarates; polymers and copolymers of 2 - chloro - butadiene; after-chlorinated polymers and copolymers of vinyl esters and ethers and of methyl methacrylate and acrylonitrile. Suitable condensation derivatives of semicarbazide are the semicarbazones of acetaldehyde, benzaldehyde, acetone and acetophenone. The stabilizers may be mixed with the resins on rolls, or by dissolving or suspending in solutions or dispersions and evaporating off the liquid media or precipitating the polymers in admixture with the stabilizers. When adding a water-soluble stabilizer to an aqueous dispersion of the polymer, an emulsifying agent may be simultaneously added as described in Specification 671,648, and the polymer isolated by spray-drying, using, for example, a rotating disc dryer or one employing an atomiser. Other heat-stabilizers may be added, including alkali metal carbonates, bicarbonates, hydroxides, borates, sulphides, phosphates, acetates and stearates, alkaline earth metal carbonates, oxides, hydroxides and salts of weak organic acids, basic organic substances, mercaptides, urea, thiourea and diphenylthiourea. Plasticizers and fillers such as dibutyl, dinonyl and di-2-ethylhexylphthalates, tricresyl phosphate, dibutyl sebacate, chlorinated paraffin waxes, lampblack, chalk, asbestos, bentonite and cork meal may also be added. Specifications 388,309, 410,837, 418,230, 450,856, 451,723, 454,232, 500,298, 526,345, 531,093, [Group VI], 536,297, 540,127, 542,141, 543,505, 570,330, 580,078, 591,611, 600,270, [Group V], and 602,312 also are referred to. |
