GB660883A - Improvements in and relating to the production of polymeric esters - Google Patents

Abstract

Copolymeric esters are made by heating together compounds of the general formul (a) <FORM:0660883/IV (a)/1> and (b) <FORM:0660883/IV (a)/2> wherein n is an integer not less than 2, R and R2 are hydrogen or acyl radicals and R1 and R3 are hydrogen or lower alkyl radicals containing from 1 to 6 carbon atoms, the heating being effected under such conditions that intermolecular interchange between the two compounds takes place. In a modification, the above copolymer is first formed and then heated with either compound (a) or a polymer obtained by autocondensation of compound (a), the heating being effected under such conditions that intermolecular interchange takes place between the copolymeric ester and compound (a) or its polymer. The condensation is preferably effected at 200-320 DEG C. and in an atmosphere of nitrogen or by bubbling nitrogen continuously through the reaction mixture, and may be carried out under reduced pressure, particularly during the later stages of the condensation. Catalysts, e.g. sulphuric acid and p-toluene sulphonic acid, may be added to the reaction mixture before or during the condensation. In examples: (1) a mixture of p-acetoxybenzoic acid, p - (b - hydroxyethoxy) - benzoic acid and p-toluene sulphonic acid was heated to 260-280 DEG C. under a stream of nitrogen at atmospheric pressure, and then at 280 DEG C. under reduced pressure, water and acetic acid being eliminated during the condensation; (2) p - (b - hydroxyethoxy) - benzoic acid was heated to 280 DEG C. under a stream of nitrogen at atmospheric pressure and then under reduced pressure. Para-toluene sulphonic acid was then added and the heating continued under reduced pressure. This product was then mixed with the product of example (1) and heated at 280 DEG C. under reduced pressure; (3) is similar to (1) except that higher temperatures were employed. The molten products were drawn out into fibres which could easily be cold drawn. Para-hydroxy-benzoic acid is another example of compound (b). Specification 604,985 is referred to.