GB590451A - Manufacture of highly polymeric linear esters - Google Patents

Abstract

Highly polymeric linear esters are prepared by heating a glycol HO(CH2)nOH, where n is an integer between 2 and 10 with a functional derivative of terephthalic acid (other than a low aliphatic ester) to form a glycol ester of terephthalic acid which is then heated at a temperature above its melting point until filaments drawn or extruded from the melt may be cold drawn. Suitable functional derivatives of terephthalic acid are half esters, esters other than low aliphatic esters, acid halides and ammonium or amine salts. Preferably, the hydroxyl component of an ester used has a boiling point below that of the glycol. When using an ester of terephthalic acid, excess glycol is preferably employed, and the displaced alcohol or phenol is removed from the reaction zone, e.g. by distillation. An ester interchange catalyst or mixture of catalysts may be employed, e.g. lithium, sodium, potassium, calcium, beryllium, magnesium, zinc, cadmium, aluminium, chromium, molybdenum, manganese, iron, cobalt, nickel, copper, silver, mercury, tin, lead, bismuth, antimony, platinum, or palladium. The catalyst may be present as powder, chips, shavings, ribbon or wire and in the proportion of .025-.1 per cent on the weight of the terephthalate ester. Alkali, or alkaline earth metals or magnesium may be used as alcoholates formed from the glycol of the reaction mixture or a monohydrin alcohol. Alkali metals may be used as carbonates or borates. Magnesium oxide may be used. When using an acid halide, a diluent and a base, e.g. pyridine, may be present. The second stage of the reaction is preferably performed under reduced pressure. The reaction is preferably carried out in absence of oxygen, e.g. with a stream of inert gas, e.g. nitrogen, passing through the mixture. The mass may be mechanically agitated. The molten polymer is removed from the reaction vessel and formed into blocks, chips, filaments or other shapes. Filaments may be cooled before cold-drawing or cold drawn immediately after formation. Passage through warm or hot water or steam before and/or during cold drawing is helpful. In the examples: (1) diphenyl terephthalate, ethylene glycol and potassium carbonate are heated together in nitrogen at 197 DEG C. for 1 hour, phenol being distilled off. Heating is continued for 30 minutes at 280 DEG C. and then for 5 hours at 1 mm. pressure. Filaments from the melt could be cold drawn into fibres; (2) ethyl or methyl hydrogen terephthalate and ethylene glycol were heated in a stream of nitrogen at 200 DEG C. After 4 hours, a mixture of lithium and magnesium was added and heating continued for 2 hours at 200 DEG C. and then raised to 285 DEG C. After 1 hour, pressure was reduced and heating continued for a further 3 hours; (3) terephthalyl chloride, ethylene glycol, pyridine and chloroform were boiled under reflux for 1 hour, cooled and poured into ether, and the separated oil shaken with hydrochloric acid. The low polymer is heated in nitrogen with magnesium as catalyst at 280 DEG C. with gradual reduction of pressure; (4) in this case, ammonium terephthalate and ethylene glycol are the starting materials; (5) this example uses the salt from triethylamine and terephthalic acid on the one hand and ethylene glycol on the other as starting materials. Specification 578,079 is referred to.