Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymerizing in tubular or loop reactor
Patent
1999-02-25
2000-08-01
Acquah, Samuel A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymerizing in tubular or loop reactor
528272, 526 65, 526 66, 526 67, 526 68, 526 71, C08F 200, C08G 8500
Patent
active
060968389
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process and an apparatus for continuous polycondensation of polymers of polyester series such as polyethylene terephthalate, polybutylene terephthalate, etc., from an aromatic dicarboxylic acid or its derivative and a glycol.
BACKGROUND ART
According to the conventional process for producing polymers of polycondensation series of polyethylene terephthalate, etc., raw materials terephthalic acid and ethylene glycol are fed to a mixing tank in an appropriate proportion for esterification and the mixture is then fed to esterification reactor tanks through a pump. In the esterification step, 2 or 3 stirring tanks each provided with stirring vanes are provided in series and a water effluent as a by-product is separated in a distillation column. A prepolymerization step follows, where a plurality of vertical stirring tanks or horizontal stirring tanks are provided, and a final polymerization step follows, where a horizontal stirring tank is provided. The tanks of these polymerization steps are each provided with a condeser for removing an effinent ethylene glycol as a by-product, and are operated in a reduced pressure atmosphere. In the conventional process for producing polyester there are 4 to 6 reactor tanks, each of which is provided with strring vanes and its power source and further provided with a distillation column or a condenser for separating and removing the by-product. Furthermore, the polymerization steps are operated in a reduced pressure atmosphere, and thus the necessary additional vacuum means for generation of a reduced pressure is required. That is, the operation of the apparatus requires a higher maintenance cost and a higher apparatus cost. One example of the related art is disclosed in JP-A 7-207009, where each tank is provided with stirring vanes and is vacuum-controlled, and thus its running or operation is complicated. That is, improved apparatus and process with a higher efficiency throughout the apparatus and economical operation based on energy saving throughout the apparatus have been so far desired for the production of high molecular weight polyester.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a process and an apparatus for continuous polycondensation, capable of efficiently producing a high molecular weight polyester.
Another object of the present invention is to provide a process and an apparatus for continuous polycondensation, capable of efficiently producing a high molecular weight polyester with simple apparatus structure and arrangement.
Other object of the present invention is to provide an apparatus for continuous polycondensation and a process for continuous polycondensation, which can overcome the problems of the above-mentioned prior art and can conduct more efficient reaction to produce polymers of good quality with a minimum energy through minimum necessary reactor structure and arrangement.
According to a first aspect of the present invention, a process for continuously producing polyester is provided, which comprises a first step of reacting an aromatic dicarboxylic acid or its derivative with a glycol in a first reactor, thereby producing an oligoester or a polyester having an average degree of polymerization of 3 to 7; a second step of polycondensing the oligoester or polyester of the first step in a second reactor, thereby producing a low molecular weight polyester having an average degree of polymerization of 20 to 40; and a third step of further polycondensing the low molecular weight polyester of the second step to an average degree of polymerization of 90 to 180 in a third reactor, thereby producing a high molecular weight polyester, wherein at least one of the first reactor and the second reactor is free from an external power soure stirring means; or wherein a reactor is used as the third reactor, which comprises a horizontal cylindrical vessel having an inlet for the low molecular weight polyester of the second step at the lower part at one end thereof and an outle
REFERENCES:
patent: 5434239 (1995-07-01), Bhatia
George Odian, "Principles of Polymerization", Second Edition, John Wiley & Sons, New York, 1981.
Harada Susumu
Nakamoto Hidekazu
Oda Chikao
Sase Yasunari
Suzuki Michio
Acquah Samuel A.
Hitachi , Ltd.
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