GB924607A - Improved process for the preparation of polyesters - Google Patents

Abstract

Polyesters, suitable for the manufacture of moulded articles, films or fibres are made by effecting ester-interchange between (a) a diphenol of formula <FORM:0924607/IV(a)/1> or an ester forming derivative thereof (e.g. the diacetate), where X may be -O-, -S-, -SO2- or an alkylene or cycloalkylene radical which may be substituted by one or more hydrocarbon radicals, halogen atoms or halogenated hydrocarbon radicals and R1, R2, R3, R4, R11, R21, R31 and R41 are hydrogen atoms, halogen atoms, hydrocarbon radicals, alkoxy radicals or nitro groups and (b) a diaryl ester of an aromatic dicarboxylic acid. Suitable diaryl esters are the diphenyl or dicresyl esters of phthalic acid and its homologues, tere- and/or iso-phthalic acid, (4,41-dicarboxydiphenyl) ether, (4,41-dicarboxydiphenyl) methane and (4,41-dicarboxydiphenyl) sulphone. The reaction mixture may also include (c) a polymethylene glycol of formula HO(CH2)xOH where x= 2-12, (d) an aliphatic dicarboxylic acid, e.g. adipic or sebacic acid, (e) a chain limiter which is a monohydroxy compound or a phenyl ester of a monocarboxylic acid, (f) a phenol having more than two hydroxyl groups, e.g. pyrogallol, hydroxyhydroquinone, phloroglucinol or 4,41,411-trihydroxy triphenyl methane or (g) an aryl ester of an acid with more than two carboxyl groups, e.g. carballylic acid or a benzene tri- or tetra-carboxylic acid. Reaction may be effected in the presence or absence of a solvent (e.g. diphenyl and/or diphenyl oxide) or a catalyst (e.g. an oxide of magnesium, lead, zinc or antimony, an alcoholate or glycolate of an alkali metal, an alkaline earth metal, magnesium, aluminium or titanium; lithium hydride or potassium borohydride; alkali salts of bis-phenols; or esters of ortho-titanic acid). The molecular weights of the polyesters may be increased by heating them above their melting points in vacuo, or by heating them in powder form, or by reacting them with a diisocyanate or diisothiocyanate. Before use, the polyesters are carefully dried. Some of the polyesters are soluble in chloroform, methylene chloride and a mixture of diphenyl and diphenyl oxide and may be precipitated from a solution in these solvents with methyl alcohol. In examples polyesters are prepared from (1) 2,2-(4,41-dihydroxy-3,31-dimethyl-diphenyl) propane (possibly in admixture with decamethylene glycol) and diphenyl terephthalate (possibly in admixture with diphenyl adipate); (2) bis-phenol A, diphenyl terephthalate and diphenyl isophthalate; (3) 2,2-(4,41-dihydroxy-3,5,31, 51-tetramethyl-diphenyl) propane and diphenyl isophthalate; (4) the diacetate of 2,2-(4,41-dihydroxy-3,31-dimethyl) propane and diphenyl terephthalate; (5) 2,2-(4,41-dihydroxy-3,31-dimethyl-diphenyl) propane and di-o-cresyl terephthalate; (6) 1,1-(4,41-dihydroxy-diphenyl) cyclohexane and diphenyl isophthalate; (7) 4,41-dihydroxy-diphenyl-sulphone and diphenyl isophthalate; (8) 2,2-(4,41-dihydroxy-3,31-dimethyl-diphenyl) propane and diphenyl terephthalate; (9) 4,41-dihydroxydiphenyl ether and the diphenyl ester of 4,41-dicarboxy-diphenyl ether; (10) 2,2-(4,41-dihydroxy-3,31-dimethyl diphenyl) propane, diphenyl terephthalate and triphenyl trimesate.