GB1013034A - Process for preparing resin - Google Patents

Abstract

A low molecular weight polyester is produced by adding a glycol and a dicarboxylic acid in a molar ratio of 1 : 1.05-1.7 to a preformed low molecular weight polyester of the glycol and acid or another low molecular weight polyester and heating at a temperature above the m.p. of the polyester present at the start of the reaction at a pressure between 20 and 1000 p.s.i.g. The polyester present at the start of the reaction has a molecular weight of 300-2000. The polyester produced may have a higher or lower molecular weight. Glycols specified are ethylene, propylene, butylene, hexylene and decylene glycols, cyclohexane diols, di-(hydroxymethyl) cyclohexanes, di-(b -hydroxy-ethoxy) benzenes, and 2,2-bis[4-(b -hydroxy-ethoxy) phenyl] propane. Acids specified are ortho-, iso- and terephthalic acids, 2,6-naphthalic acid, diphenyl-4,41-dicarboxylic acid, hexahydroterephthalic acid, succinic, adipic and sebacic acids. A copolyester may be prepared from a mixture of acids. The condensation may take place under an N2 atmosphere with stirring at a maximum temperature of 300 DEG C. A catalyst, e.g. zinc or manganous acetate, or an alkali metal alkoxide, may be used. Water vapour may be distilled out at such a rate that the pressure remains constant and a reflux condenser may be used to return ethylene glycol vapour to the reactor. The process may be continuous, a weight of low molecular weight polyester, equal to the weights of acid and glycol added, being withdrawn continuously. The low molecular weight product may be polymerized by addition of a catalyst, e.g. Sb2O3, zinc borate, litharge, lead acetate or MgO, to give a product of intrinsic viscosity of at least 0.40. This reaction may occur under an N2 atmosphere, at a temperature of 260-290 DEG C. and at a pressure below 10 mm. Hg. The eliminated glycol may be recovered. The process may be continuous and the product may be made into films or fibres.ALSO:A polyester of degree of polymerization 1.4-10 is produced by adding a glycol and a dicarboxylic acid in a molar ratio of 1: 1.05-1 7 to a preformed low molecular weight polyester of the glycol and acid or another low molecular weight polyester and heating at a temperature above the m.p. of the polyester present at the start of the reaction and at a pressure of 20-1000 p.s.i.g. The polyester present at the start of the reaction may have a M.W. of 300-2000. The polyester produced may have a higher or lower molecular weight. Glycols specified are: ethylene, propylene, butylene, hexylene and decylene glycols, cyclohexane diols, di-(hydroxymethyl) cyclohexanes, di-(b -hydroxyethoxy) benzenes, and 2,2-bis-[4-(b -hydroxyethoxy) phenyl]propane. Acids specified are g -, iso- and terephthalic, 2,6-naphthalic, diphenyl - 4,41 - dicarboxylic, hexahydroterephthalic, succinic, adipic and sebacic acids. A copolyester may be prepared from a mixture of acids. The condensation may take place under an N2 atmosphere with stirring at a maximum temperature of 300 DEG C. A catalyst, e.g. zinc or manganous acetate or an alkali metal alkoxide may be used. Water vapour may be distilled out at such a rate that the pressure remains constant and a reflux condenser may be used to return ethylene glycol vapour to the reactor. The process may be continuous.