US 7,732,556 B2 · Process of producing polyesters

Abstract

A problem of the invention is to provide a process of producing polyesters having a stable quality and a process of producing polyesters with a greatly reduced load against the environment. The invention relates to a process of producing polyesters by using a polycondensation reaction apparatus provided with one or more sets of an ejector, a condenser placed in the downstream portion of the ejector and a hot well tank connected to the condenser via a barometric leg and including a step of driving the ejector by a vapor composed mainly of 1,4-butanediol, condensing the vapor composed mainly of 1,4-butanediol as discharged from the ejector in the condenser placed in the downstream portion of the ejector, and making the reactor in a reduced pressure state to undergo polycondensation reaction, characterized in that the concentration of tetrahydrofuran contained in a sealing liquid in at least one hot well tank is not more than 4% by weight.

Claims20

Dependent claims

A process of producing polyesters having a stable intrinsic viscosity by using a polycondensation reaction apparatus having one or more polycondensation reaction vessels provided with one or more sets of an ejector, an upstream condenser placed between the polycondensation reaction vessel and the ejector, a condenser placed in the downstream portion of the ejector, a barometric leg, and one or more hot well tanks connected to the condenser via the barometric leg, wherein the upstream condenser is equipped with a collection tank for collecting a condensate obtained from condensing a vaporous composition obtained from the polycondensation reaction vessel, and

including driving the ejector by a vapor composed mainly of 1,4-butanediol, condensing the vapor composed mainly of 1,4-butanediol as discharged from the ejector in the condenser placed in the downstream portion of the ejector, and making the reactor in a reduced pressure state to undergo polycondensation reaction, the process being characterized in that:
water contained in a sealing liquid in at least one hot well tank is maintained at a concentration of not more than 3% by weight;
and
tetrahydrofuran contained in a sealing liquid in at least one hot well tank is maintained at a concentration of not more than 4% by weight to thereby produce polyesters having a stable intrinsic viscosity.

1 more element

A process of producing a polyester having a stable intrinsic viscosity with a polycondensation reaction apparatus,

wherein said polycondensation reaction apparatus comprises one or more polycondensation reactors each operating at a stable reduced pressure and independently equipped with, in successive order, one or more of each of the following:
upstream condensers equipped with a collection tank for collecting a condensate obtained from condensing a vaporous composition obtained from the polycondensation reactor;
vapor driven ejectors;
downstream condensers;
barometric legs;
and hot well tanks comprising a sealing liquid obtained from said downstream condensers via said barometric legs, and
wherein said process comprises:
driving said one or more vapor driven ejectors with a vapor predominantly comprising 1,4-butanediol;
maintaining a water concentration of not more than 3 wt. % within said sealing liquid of at least one of said one or more hot well tanks;
and
maintaining a tetrahydrofuran concentration of less than or equal to 4 wt. % within said sealing liquid of at least one of said one or more hot well tanks to thereby produce polyesters having a stable intrinsic viscosity.

8 more elements

Dependencies are inferred from the claim text.

Process of producing polyesters

Life of this patent

Process of producing polyesters

Life of this patent

Abstract

Claims20