Patent GB-984648-A (GB)
Title: Process for the production of elastomeric yarns
IPC: B29C71/04
Filed: 1963-05-17
Abstract: 984,648. Elastomeric ethylene-vinyl acetate copolymer yarns. FARBENFABRIKEN BAYER A.G. May 17, 1963 [May 17, 1962 : Oct. 17, 1962],No. 19811/63. Heading B5B. Elastomeric yarns are made by spinning an ethylene-vinyl acetate copolymer containing 30 to 65% by weight of vinyl acetate and subjecting the yarns obtained to radical-induced cross-linking. Preferably the copolymer contains 40-55% by weight of vinyl acetate. Dry-, wet-, or melt-spinning methods may be used, and the radical-induced cross-linking ef the spun yarns may be effected by highonergy radiation, e.g. #-rays, electron rays or neutron beams, by the use of a cross-linking agent followed by treatment at high temperatures or by a combination of these two methods of cross-linking. Using such a-combination of methods, high-energy radiation is not essential and may be replaced by ultra-violet radiation. For the radical-induced cross-linking, a crosslinking agent may be mixed with the copolymer and the yarns obtained heated to temperatures above the spinning temperature. Copolymers with a molecular weight above 10,000 and advantageously above 20,000 or 30,000 are preferred. Fillers, e.g. active carbon black, active aluminium hydroxide or barium sulphate and silica, stabilizers, plasticizers and pigments, may be added to the copolymer before spinning, and so may cross-linking auxiliaries. Specified cross-linking agents, which are advantageously added to the polymer before spinning in proportions of 0À5- 10% by weight, especially 1-5%, include benzoyl peroxide, dichlorobenzoyl peroxide, peroxydicarbonates, di-t-butyl peroxide and t-butyl cumyl peroxide, peroxydicarbonates decomposing at temperatures below 100‹ C. being preferred, except for melt-spinning where the peroxides, which decompose only at higher temperatures, are used. Cross-linking auxiliaries are monomers containing at least two polymerizable carbon-carbon double bonds and are suitably added in a proportion of 1-10% by weight. Those specified include divinyl benzene, trivinyl benzene, ethylene glycol dimethacrylate, phthalic acid dialdehyde ester, diallyl fumarate, triallyl cyanurate, triallyl phosphate, triallyl ethers of glycerol and tetraallyl and hexa-allyl ethers of hexamethylol melamine. Melt-spinning may be effected at 80-200‹ C. For solution-spinning, aromatic hydrocarbons, halogenated aliphatic and aromatic hydrocarbons, ethyl acetate, tetrahydrofuran, dioxane and t-butanol may be used as spinning solvents, from solutions in which the copolymers may be spun at temperatures below 100‹ C. Dry-spinning may be effected at from room temperature to 120‹ C. depending on the spinning solvent used. For wet-spinning, non- solvents as for example water and methanolare used in the precipitating baths together with a proportion of solvents. Melt-spun yarns obtained are heated, preferably with exclusion of air, to 100-120‹ C. and cross-linking then occurs. Wet- or dry-spun yarns are heated to 40-150‹ C., preferably 40-100‹ C., to induce cross-linking. Examples of melt, dry- and wetspinning methods are given. Specifications 843,974 and 905,042 is referred to.