Elastic linear copolyesters and process of making them

Abstract

Abstract Elastic co-polyesters are produced by melt polymerization of a glycol HO (CH2)n OH (where n = 2-6) an acid HOOC CH2 X CH2 COOH where X is a linear chain of 4-9 atoms, not more than three of which may be oxygen the remainder being saturated hydrocarbon carbon atoms which contain not more than 3 carbon atoms as side chain substituents, any two oxygen atoms being separated by at least two carbon atoms and 30-44 per cent. by weight of the total acid component of terephthalic, bibenzoic, ethylene -bisp-oxybenzoic, tetramethylene -bisp oxybenzoic or 2, 6-naphthalic acid. The glycol is present in stoichiometric excess. Acyclic acids mentioned include inter alia suberic, sebacic, azelaic, oxydibutyric, 5-ox- 1, 10- decanedioic, undecanedioic, 4-n-propyl suberic. Mixtures of aliphatic acids and of aromatic acids may be employed. The acids may be employed as methyl esters. When the reaction mixture reaches the desired intrinsic viscosity it may be extruded to form chips which may be melted to form shaped articles. Yarns or films may be drawn with relaxation periods and may be heat treated to prevent tackiness, to produce desired elastic properties and to reduce shrinkage on heating. In examples (1), 120 parts of dimethyl terephthalate, 280 parts of dimethyl sebacate and excess glycol are heated to produce a polymer of intrinsic viscosity 1.0. This is drawn and relaxed to a net draw ratio of 3.5, and then aged. (2) and (3) copolyesters are produced from the dimethyl ester of ethylene bisp-oxybenzoic acid and dimethyl sebacate with excess ethylene glycol, and are spun into fibres. (4) Tetramethylene bisp-oxy benzoic acid, dimethyl sebacate and ethylene glycol are employed. (5) The raw materials are dimethyl bibenzoate, dimethyl sebacate and ethylene glycol. (6) The materials used are terephthalic acid; 5, 8- dioxo- 1, 12, -dodecane-dioic acid and ethylene glycol. The physical properties of yarns prepared from the copolyesters of the invention are summarized and a list of articles for which they may be used is given. The polyesters may also be used for adherent elastic coatings, elastic film, heat shrinkable bottle covers, safety glass interlayers, oil-resisting gaskets, flexible tubing or wire coating.

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