US 4,046,739 AGranted

Process for reducing the processing time in the production of polyesters

AssigneeKoppers Company, Inc.

InventorJoseph Lacona

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Abstract

Polyesters obtained by reacting isophthalic acid or terephthalic acid with a polyol with or without a catalyst in a first stage to form a half-ester mixture which is reacted in a second stage with an aliphatic polycarboxylic acid are produced at reduced processing times. In the first stage a portion of the total polyol to be reacted is contacted with substantially all of the isophthalic acid or terephthalic acid. Then, this mixture is heated to a temperature of at least 190.degree. C. and the remaining portion of the polyol is added to the heated mixture in such a manner that the temperature remains at or above the 190.degree. C. This temperature is maintained until the reaction to form a half-ester mixture is completed. This reaction may be conducted in the presence of an esterification catalyst. The polyester-monomer mixture is reacted in a second stage with an aliphatic polycarboxylic acid to produce the polyester.

Claims9

Dependent claims

In a two-stage process for the production of polyesters wherein an aromatic polycarboxylic acid selected from the group consisting of isophthalic acid and terephthalic acid is reacted in the first stage with a polyol to produce half-ester mixture which is reacted with a saturated or unsaturated aliphatic polycarboxylic in the second stage to produce the polyester, the improvement, to reduce the processing time in the first stage;

thereby reducing the processing time for the production of the polyester, comprising:
a. contacting first portion of the polyol with the aromatic polycarboxylic acid in the first stage in an amount at least sufficient to form an agitatable mixture with the aromatic polycarboxylic acid but in an amount slightly less than the theoretical amount of polyol needed to react with the isophthalic acid or terephthalic acid and saturated or unsaturated aliphatic polycarboxylic acid,
b. heating the agitatable mixture to a temperature of at least 190.degree. C to 230.degree. C, and
c. adding the remaining portion of the polyol to the heated agitatable mixture in the first stage in such a manner that the temperature of the heated agitatable mixture is maintained at a temperature of at least 190.degree. C in order to produce a half-ester mixture.

1 more element

Dependencies are inferred from the claim text.