GB1047043A - Linear superpolyester production - Google Patents

Abstract

A linear polyester is produced by solid phase polymerization of particles of a prepolymer of a glycol and a dicarboxylic acid in a stream of dry air or inert gas of atmospheric pressure and in the presence of an Sb or Mn catalyst. Glycols specified are ethylene, butylenes, pentylene and neopentylene glycols, 1,4-di-(hydroxymethyl) cyclohexane 2,2,4,4 - tetramethylcyclobutane - 1,3 - diol and polybutylene glycol. 50% or more of the dicarboxylic acid may be an acid comprising 2 carboxyl groups directly linked to a hexacarbocyclic nucleus, e.g. terephthalic acid, naphthalene-2,6-dicarboxylic acid or diphenyl sulphone-4,41-dicarboxylic acid. The remainder may be dimethyl malonic, succinic or adipic acid. The catalyst may be 0.01-0.5% Sb2O3 and 0.005-0.2% manganous acetate in the ratio 30:1-600. The reaction may be carried out in a polymerization zone, 5% or more of which is occupied by prepolymer particles having an inherent viscosity of 0.1-0.45, all the particles being capable of passing through a 20-mesh screen and less than 25% passing through a 200 mesh screen. The reaction may be at 175-300 DEG C. and the particles may be in a static bed 0.5 mm. thick or may be agitated by the gas stream, by stirring or in a tube of corrugated cross-section inclined to the horizontal and rotated about its longitudinal axis. The inert gas may be N2, CO2, He, propane or dried burned natural gas containing no more than 0.1% CO. 10-1000 ml./min./g. of particles may be used. The exhaust gas may be recycled. The product may be made into fibres, films or shaped articles. In Example (1) dimethyl terephthalate and 1,4-di-(hydroxymethyl) cyclohexane were reacted in a N2/CO2 mixture containing less than 2% O2 to give prepolymer particles suitable for further polymerization.