Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymerizing in two or more physically distinct zones
Reexamination Certificate
2000-02-11
2002-03-05
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymerizing in two or more physically distinct zones
C528S272000, C528S308600, C526S067000, C526S068000, C526S071000
Reexamination Certificate
active
06353062
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a continuous process for the production of poly(trimethylene terephthalate), which is also commonly referred to as poly(1,3-propylene terephthalate). The process of the invention can be used as part of a three-vessel process, the first vessel being either an ester exchanger for producing a mixture of bis-3-hydroxypropyl terephthalate and low molecular weight polymers of 1,3-propanediol and terephthalic acid having an average degree of polymerization of 15 or less from dimethylterephthalate and 1,3-propanediol or a reactor for producing the starting material from terephthalic acid and 1,3-propanediol. The second vessel is a prepolymerizer, and the third vessel is a final polymerizer or finisher.
BACKGROUND OF THE INVENTION
Continuous, three-vessel processes are known for the production of poly(ethylene terephthalate). For example, Vodonik, U.S. Pat. No. 2,727,882 discloses a process for the continuous polymerization of bis-2-hydroxyethyl terephthalate using a prepolymerizer.
Also known are batch processes for the production of poly(trimethylene terephthalate). For example, Doerr et al., U.S. Pat. No. 5,340,909 discloses the production of poly(trimethylene terephthalate) using either an ester exchange reaction starting with lower dialkyl terephthalate ester or direct esterification of terephthalic acid followed by a polycondensation reaction, both of which are carried out in batches using an autoclave.
It would be highly desirable to provide a continuous, three-vessel process for the production of poly(trimethylene terephthalate). It would also be desirable to provide a continuous process for the production of poly(trimethylene terephthalate) in which the production of by-products, such as acrolein and allyl alcohol, is minimized and in which the molecular weight of the final poly(trimethylene terephthalate) polymer is maximized. The present invention provides such a process.
SUMMARY OF THE INVENTION
The invention comprises a continuous process for the production of poly(trimethylene terephthalate) comprising the steps of:
(a) continuously feeding a liquid feed mixture to a prepolymerizer, the liquid feed mixture comprising at least one of bis-3-hydroxypropyl terephthalate and low molecular weight polyesters of 1,3-propanediol and terephthalic acid, and the liquid feed mixture having a mole ratio of propylene groups to terephthalate groups of 1.1 to 2.2;
(b) continuously polymerizing bis-3-hydroxypropyl terephthalate and said low molecular weight polyesters to form a poly(trimethylene terephthalate) prepolymer and a first stream of gaseous by-products;
(c) continuously withdrawing the poly(trimethylene terephthalate) prepolymer from the prepolymerizer, the prepolymer having a relative viscosity of at least about 5;
(d) continuously feeding the poly(trimethylene terephthalate) prepolymer to a final polymerizer and continuously polymerizing the poly(trimethylene terephthalate) prepolymer to form a higher molecular weight poly(trimethylene terephthalate) and a second stream of gaseous by-products; and
(e) continuously withdrawing the higher molecular weight poly(trimethylene terephthalate) from the final polymerizer, the higher molecular weight poly(trimethylene terephthalate) having a relative viscosity of at least about 17.
REFERENCES:
patent: 2727882 (1955-12-01), Vodonik
patent: 2829153 (1958-04-01), Vodonik
patent: 2932625 (1960-04-01), Burton et al.
patent: 2933476 (1960-04-01), Fisher
patent: 2973341 (1961-02-01), Hippe et al.
patent: 3054776 (1962-09-01), Higgins
patent: 3167531 (1965-01-01), Parker et al.
patent: 3192184 (1965-06-01), Brill
patent: 3534082 (1965-12-01), Armstron et al.
patent: 3438942 (1969-04-01), Scheller et al.
patent: 3441540 (1969-04-01), Muller et al.
patent: 3506622 (1970-04-01), Higgins
patent: 3609125 (1971-09-01), Fujimoto et al.
patent: 3676485 (1972-07-01), Lewis et al.
patent: 3936421 (1976-02-01), Hayashi et al.
patent: 4049635 (1977-09-01), Cleary
patent: 4056514 (1977-11-01), Strehler et al.
patent: 4096122 (1978-06-01), Schade et al.
patent: 4110316 (1978-08-01), Edging et al.
patent: 4289895 (1981-09-01), Burkhardt et al.
patent: 5340909 (1994-08-01), Doerr et al.
patent: 5434239 (1995-07-01), Bhatia
patent: 5459229 (1995-10-01), Kelsey et al.
patent: 5466776 (1995-11-01), Krautstrunk et al.
patent: 5510454 (1996-04-01), Stouffer et al.
patent: 5540868 (1996-07-01), Stouffer et al.
patent: 5552513 (1996-09-01), Bhatia
patent: 5559205 (1996-09-01), Hansen et al.
patent: 5599900 (1997-02-01), Bhatia
patent: 5633018 (1997-05-01), Stouffer et al.
patent: 5663281 (1997-09-01), Brugel
patent: 5670606 (1997-09-01), Stouffer et al.
patent: 5677415 (1997-10-01), Bhatia
patent: 5688898 (1997-11-01), Bhatia
patent: 5703179 (1997-12-01), Asakura et al.
patent: 5763104 (1998-06-01), Stouffer et al.
patent: 5786443 (1998-07-01), Lowe
patent: 5798433 (1998-08-01), Schmidt et al.
patent: 5811496 (1998-09-01), Iwasyk et al.
patent: 5840957 (1998-11-01), Kurian et al.
patent: 5849849 (1998-12-01), Bhatia
patent: 5891985 (1999-04-01), Brugel
patent: 5990265 (1999-11-01), Blanchard et al.
patent: 6277947 (2001-06-01), Kelsey et al.
patent: 97/21754 (1997-06-01), None
Traub et al., Mechanical Properties of Fibers Made of Polytrimethylene Terephthalate,Chemical Fibers International, 45, 110-111, Apr. 1995.
Schauhoff et al.,, New Developments in the Production of Polytrimethylene Terephthalate (PTT),Man-Made Fiber Year Book, Sep. 1996.
Duffy Joseph James
Giardino Carl J.
Griffith David B.
Ho Chungfah Howard
Howell James M.
Acquah Samuel A.
E. I. Du Pont De Nemours and Company
Kuller Mark D.
Mayer Nancy S.
LandOfFree
Continuous process for producing poly(trimethylene... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Continuous process for producing poly(trimethylene..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuous process for producing poly(trimethylene... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2836385