Apparatus for crystallization of polytrimethylene terephthalate

Chemical apparatus and process disinfecting – deodorizing – preser – Physical type apparatus – Crystallizer

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

Reexamination Certificate

active

06461575

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to the preparation of 1,3-propanediol-based polyesters such as polytrimethylene terephthalate. In one aspect, the invention relates to apparatus for the continuous crystallization of polytrimethylene terephthalate.
Polytrimethylene terephthalate is a polyester useful in fiber applications in the carpet and textile industries. The manufacture of polytrimethylene terephthalate involves the melt condensation polymerization of 1,3-propanediol and terephthalic acid to a polymer having an intrinsic viscosity (IV) of about 0.5 to 1.0 dl/g. The polymer melt is discharged from the bottom of the melt reactor and extruded through an extrusion die into strands. The strands are quenched in cold water and cut into pellets for storage or transportation.
It has been found that polytrimethylene terephthalate pellets tend to stick together, or “block,” during storage or shipping at temperatures above the polymer Tg (about 45° C.), which can be exceeded during the summer in a silo or rail car. Agglomeration of the pellets complicates and increases the cost of handling the pellets. Applicants have found that partially crystallized polytrimethylene terephthalate pellets are less susceptible to blocking, and applicants have developed a process for partial crystallization of polytrimethylene terephthalate pellets. It would be desirable to practice such a process in the continuous polymerization of polytrimethylene terephthalate.
It is therefore an object of the invention to provide apparatus for crystallizing polytrimethylene terephthalate pellets in a continuous polymerization process.
BRIEF SUMMARY OF THE INVENTION
According to the invention, the polyester product of condensation polymerization of 1,3-propanediol and terephthalic acid is partially crystallized in a vessel designed to provide immersion of polytrimethylene terephthalate pellets in a continuous moving liquid bed at a temperature within the range of about 65 to about 100° C. for a time effective to achieve a crystallinity of at least about 35% and a pellet density of at least about 1.33 g/cm
3
.


REFERENCES:
patent: 3661330 (1972-05-01), Yamada et al.
patent: 4265740 (1981-05-01), Luthi
patent: 5532335 (1996-07-01), Kimball et al.
patent: 5540868 (1996-07-01), Stouffer et al.
patent: 5763104 (1998-06-01), Stouffer et al.
patent: WO 97/23543 (1997-07-01), None

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Apparatus for crystallization of polytrimethylene terephthalate does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Apparatus for crystallization of polytrimethylene terephthalate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for crystallization of polytrimethylene terephthalate will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-2933677

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.