Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1998-02-19
1999-04-27
Mosley, Terressa
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528271, C08G 6400
Patent
active
058980598
ABSTRACT:
Disclosed is a process for the production of polyethylene terephthalate (PET), comprising the steps of (i) reacting di(C.sub.1 -C.sub.4)alkyl terephthalate with ethylene glycol to yield bis-(2-hydroxyethyl) terephthalate, (ii) adding a sequestering agent based on phosphorus and (iii) polycondensing the bis-(2-hydroxyethyl) terephthalate to produce PET; wherein in step (i) a zinc catalyst is present and in step (iii) an antimony catalyst is additionally present, the amount of zinc being in the range of from 0.003 to 0.008% by weight (30 to 80 ppm), the amount of phosphorus being in the range of from 0.001 to 0.01% (10 to 100 ppm), and the amount of antimony being in the range of from 0.01 to 0.05% by weight (100 to 500 ppm), in each case such weights being relative to the weight of the di(C.sub.1 -C.sub.4)alkyl terephthalate; the molar ratio of the antimony to the zinc being in the range of from 1:0.95 to 1:0.1; and the value, obtained by multiplying the molar ratio of the phosphorus to the zinc by the molar amount of antimony, is 4 or less. The PET produced in the process according to the invention contains a low number of particles, generally less than 400 per microgram, and can be formed into articles having a very smooth surface with only a minimum number of protrusions.
REFERENCES:
patent: 3907754 (1975-09-01), Tershansy et al.
patent: 4010145 (1977-03-01), Russin et al.
patent: 4122107 (1978-10-01), Kenney
patent: 5153164 (1992-10-01), Mason
S.G. Hovencamp, "Kinetic Aspects of Catalyzed Reactions in the Formation of Poly(ethylene terephthalate)", J. polymer Sci., Part A-1, vol. 9 (1971).
Clements Gregory N.
Hoechst Diafoil Company
Mosley Terressa
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