Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1989-09-18
1990-10-16
Kight, III, John
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528298, 528483, 528502, 528503, C08G 6388
Patent
active
049636448
ABSTRACT:
High molecular weight polyester resins are sometimes produced from low molecular weight polyester prepolymers having the same composition by solid state polymerization. Polyester prepolymers are generally converted from the amorphous state to the crystalline state prior to solid state polymerization in order to raise their sticking temperature. This is done to keep the polyester prepolymer from sticking together as a solid mass in the solid state polymerization reactor. Such polyester prepolymers are traditionally crystallized by simply heating them to an elevated temperature at which crystallization occurs. However, polyethylene naphthalate prepolymer cannot be crystallized by utilizing this simply traditional approach. This inventions discloses a process for crystallizing amorphous polyethylene naphthalate prepolymer which comprises: (1) heating the amorphous polyethylene naphthalate prepolymer to a temperature which is within the range of about 80.degree. C. to about 140.degree. C. in the presence of a stream of an inert gas or under a vacuum to devolatilize the amorphous polyethylene naphthalate prepolymer; and (2) subsequently heating the devolatilized polyethylene naphthalate prepolymer to a temperature which is within the range of about 150.degree. C. to about 260.degree. C. while providing agitation to produce the crystallized polyethylene naphthalate prepolymer.
REFERENCES:
patent: 4327205 (1982-04-01), Kato et al.
patent: 4374975 (1983-02-01), Duh
patent: 4755587 (1988-07-01), Rinehart
patent: 4792573 (1988-12-01), Cohn
patent: 4849497 (1989-07-01), Scannapielo
patent: 4876326 (1989-10-01), Rinehart
Acquah Sam A.
Kight III John
Rockhill Alvin T.
The Goodyear Tire & Rubber Company
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