CS223463B1 - A process for the continuous preparation of polyesters modified with isophthalic acid derivatives - Google Patents

Abstract

The method of continuous production of polyester fibers modified with isophthalic acid derivatives according to the invention allows the production of both coagulating and non-coagulating copolyester fibers on continuously operating production lines equipped with direct copolymer melt spinning. The liquid copolymer, which is a solution or melt of the modifying component, is continuously dosed into the production line to the part in which the exchange esterification of dimethyl terephthalate with ethylene glycol takes place or to the initial stage of polycondensation in such an amount that the copolymer contains the desired proportion of the isophthalic component. The point of entry of the modifying component into the continuously operating production line is determined with regard to the composition of the used modifying comonomer and its temperature. The product is a directly spun copolyester fiber.

Description

The present invention provides a process for the production of polyester fibers modified with isophthalic acid derivatives by a continuous process.

Polyester fibers modified with isophthalic acid derivatives are known and are produced in staple and non-staple form in the form of staple fibers. The production of aa is carried out by a batch production process and consists in the interchangeable eaterification of dimethyl terephthalate and dimethyl isophthalate with ethylene glycol, in which ae releases methanol to give a mixture of terephthalic acid and isophthalic acid bia- (2-hydroxyethyl) ester which copolycondensate in a subsequent manufacturing operation. After cooling, the fiber copolymer is granulated, dried and melt-spun. The batch process of preparing copolyeeters is disadvantageous. The continuous production of polyester fibers in a continuous flow reactor system operating in a different process mode, where raw materials enter the first and continuously melt the polymer melt, which is directly spinning, is simpler and more economical than the batch process. The continuous production eliminates the granulation and drying of the polymer and the energy consumption and labor consumption is reduced. Direct addition of isophthalic component with major. The raw materials for entry into a continuously working line are technically demanding and difficult because it is a solid dosage in the prescribed ratio to the main components.

The production of polyesters and the content of isophthalic component on a continuously operating production plant is made possible by the process according to the invention according to which a continuous solution of bis- (2-hydroxyethyl) isophthalic acid eater in ethylene glycol is added. to the production line for continuous production of polyester fiber. The added component is liquid and feeds into the production line in an amount set according to the line power and the desired proportion of the modifying component in the fiber being produced. Mode 2 entry point to the production line It is chosen that the ethylene glycol content of the modifier component is less than or equal to the mainstream ethylene glycol component of the production line · The ei preparation component is prepared in the auxiliary plant by esterification of isophthalic acid with ethylene glycol

The process according to the invention makes it possible, in the production of the isophthalic component-modified polyester fiber, to achieve the economic advantages of higher quality of prepared co-polyester and lower energy and equipment costs. These lower costs result from the fact that the method according to the invention does not require a separate solid addition melter or control of the ratio of the addition of the modifying component to the main terephthalic component. The advantage is also the possibility to switch from production modified to unmodified fiber and to the opposite with low polymer losses, because the production line works in both cases at the same technological mode before entering the modifying component.

Example 1

The ethylene glycol interchangeable dimethyl terephthalate exchange was carried out in a cascade of seven stirred flow reactors so that the molar ratio of the incoming dimethyl terephthalate to ethylene glycol was 1: 1 > The dosage of dimethyl terephthalate was 430 kg / h, and ethylene glycol was dosed with manganese acetate in an amount of 0.11 wt.%, Antimony triethyl acetate in an amount of 0.12 wt. A solution of bis (2-hydroxyethyl) phthalic acid bis- (2-ethyl) ester (HEX) in ethylene glycol β at a concentration of 75 h ester and a temperature of 445 K was continuously fed to the first member such that the molar ratio of terephthalic to isophthalic was 23: 2. The solution contained 0.15 wt% zinc oetane, calculated on HEI. The product from the cascade of stirred reactors was further copolycondenzone in three stages. In the first stage, which was a stirred flow reactor, the temperature was 538 K and the absolute pressure was 14.3 kPa. The second and third stages consisted of horizontal cylindrical internal reactors which provided piston flow, with the second stop having a temperature of 553 K and an absolute pressure of 0.93 kPa and a third stage of 560 K and an absolute pressure of 0.46 kPa. The co-polymer obtained was continuously directly

- 3 223 463 fiberized. The fiber exhibited similar physical and structural properties as the batch process fiber. While the fiber obtained by the batch process could only be processed as staple fiber, the modified fiber produced by the process of the invention was applicable to the more modern processing process in the form of cutting and shredding cables.

Example 2

The apparatus and procedure of Example 1 were interchanged with dimethyl terephthalate by ethylene glycol, with a temperature of 506 ° C in the last Siene of the stirred reactor cascade, and the product contained 4% free ethylene glycol, and the exchange esterification conversion was consistently greater than 99%. A melt containing 34 wt% of isophthalic acid bis- (2-hydroxyethyl) ester, 36 wt% of its dimer and 30 wt% of its trimer was continuously introduced into the reactor. By copolycondensation of this melt with the reaction mixture from the cascade of stirred reactors in the first polycondensation reactor, a prepolycondensate was obtained which, after passing through the other two polycondensation reactors, was directly spun and the resulting fiber had properties identical to the β fiber stranded according to Example 1.

Claims (1)

SUBJECT OF THE INVENTION Process for the continuous preparation of modified polyesters with isophthalic acid derivatives, characterized in that the modifying component, which is a melt of the isophthalic acid esterification product or the dimethyl ester isophthalate esterification with ethylene glycol containing up to 5% free ethylene glycol, is continuously introduced and mixed with the main ester exchange product. dimethyl terephthalate with ethylene glycol or esterification of terephthalic acid with ethylene glycol containing up to 20K% free ethylene glycol, wherein the molar ratio of isophthalic to terephthalic component is set to between 0.005 and 0.2, the free ethylene glycol content of the melt of the modifier component is not mainstream and the temperature difference of the two mixed streams is not more than 150 K.