Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1987-03-26
1988-07-05
Phynes, Lucille M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
5283082, 528483, 528502, C08G 6302, C08G 6326
Patent
active
047555874
ABSTRACT:
High molecular weight polyester resins such as polyethylene terephthalate, are sometimes produced from low molecular weight polyester prepolymers having the same composition by solid state polymerization. The low molecular weight polyester prepolymers which are used in such solid state polymerizations are normally prepared by conventional melt polymerizations and are generally in the form of pellets or chips. It has been unexpectedly found that solid state polymerization rates can be greatly improved by utilizing polyester prepolymers which are in the form of porous pills. By utilizing polyester prepolymers that are in the form of porous pills, higher molecular weights can be achieved after shorter solid state polymerization times.
The present invention specifically relates to an improved process for solid state polymerizing a polyester prepolymer into a high molecular weight polyester resin comprising heating the polyester prepolymer to an elevated temperature which is sufficient to induce solid state polymerization, wherein the polyester prepolymer is in the form of porous pills. The porous pills utilized in such solid state polymerizations generally have a density within the range of about 70% to about 96% of the density of solid polyester pellets which are comprised of the polyester prepolymer and weigh from about 0.02 to about 0.5 grams.
REFERENCES:
patent: 3586647 (1971-06-01), Kremer
patent: 4327205 (1982-04-01), Kato et al.
patent: 4374975 (1983-02-01), Duh
Phynes Lucille M.
Rockhill Alvin T.
The Goodyear Tire & Rubber Company
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