Polybutylene terephthalates having a low carboxyl content and co

Details Polybutylene terephthalates having a low carboxyl content and co Polybutylene terephthalates having a low carboxyl content and co

1978-12-13

1980-07-15

Phynes, Lucille M.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From carboxylic acid or derivative thereof

528302, 528307, 528309, 528483, C08G 6318

Patent

active

042129630

ABSTRACT:
Polybutylene terephthalates having a narrow molecular weight distribution, a low carboxyl group content and an intrinsic viscosity of from 0.2 to 1.4 dl/g can be continuously produced by transporting a molten reaction mixture of terephthalic acid mono- and/or bis-(hydroxybutyl) ester or low viscosity polybutylene terephthalate at 160.degree. to 300.degree. C., together with a heated inert gas, in a diphasic annular stream through an externally heated spiral reaction tube (of substantially constant pitch) having a diameter of from 3 to 100 mm and a diameter/length ratio of from 1:400 to 1:2000 by the maintenance of a pressure difference between the beginning and the end of the reaction tube, under conditions such that the absolute pressure, determined at the point of entry of the reaction mixture into the tube, is from 1 to 100 bar and the viscosity of the annular stream is from 1 to 10,000 poises (determined at the reaction temperature), and a circular stream between the surface of the melt and the wall of the tube is produced by the curvature of the tube and a stream of gas flowing at a velocity of from 20 to 300 m/sec to accelerate the transport of material between the melt and the inert gas, whereby the reaction takes place in the liquid phase and/or at the melt/gas interface.

REFERENCES:
patent: 3550669 (1970-12-01), Lippert et al.
patent: 3692744 (1972-09-01), Rich et al.
patent: 3834441 (1974-09-01), Vernaleken et al.
patent: 3859257 (1975-01-01), Schade et al.
patent: 3953404 (1976-04-01), Borman
patent: 4056514 (1977-11-01), Strehler et al.

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