Patent ID: 9714321
Date: 2017-07-25
CPC Classifications: C08G,D01F

Claim:
1. A continuous polymerization process for manufacturing a polyester, the process comprising the following steps: a) employing an assembly comprising an initial reactor vessel, a final reactor vessel and an intermittent reactor vessel, where said reactor vessels are connected to each other through one or more transfer lines; b) introducing reactant components comprising a terephthalic acid slurry comprising terephthalic acid and ethylene glycol and a TiO c) stirring the reactant components in the initial reactor vessel at a speed of greater than 0 to less than 200 rpm to form an oligomer; d) transferring the oligomer produced in the initial reactor to the intermittent reactor vessel and stirring the oligomer in the intermittent reactor vessel at a speed ranging from 400 rpm to 1000 rpm; e) introducing about 10 ppm to 100 ppm phosphoric acid and at least one additive selected from carbon black having a particle size of about 0.02 μm to about 1 μm or a member of the group consisting of 5-sulfoisophthalic acid (SIPA), 5-sulfoisophthalic acid dimethyl ester (SIPM), 5-sulfoisophthalic acid diglycolate (SIPEG), and alkali metal salts thereof to the oligomer being stirred at 400 rpm to 1000 rpm in the intermittent reactor vessel, wherein the at least one additive is blended into the oligomer and an intermediate is obtained, and wherein the oligomer, the at least one additive, and the phosphoric acid have a residence time of from 1 minute to 5 minutes in the intermittent vessel; f) transferring the intermediate to the final reactor vessel; and g) polymerizing the intermediate in the final reactor vessel at a temperature of from 285° C. to 320° C. and in the absence of a polyethylene glycol, to obtain the polyester.