CS234505B1 - A method of continuously preparing chemically modified polyester fibers - Google Patents

Abstract

A method for producing various types of copolymer fibers, in which the direct spinning of the esterification of copolymerizing acids with ethylene glycol is carried out in an environment formed by the product of the low-molecular part of a continuously operating production line, a part of which is branched off into a special flow reactor arranged in parallel with the production line, the product from this reactor being combined with the main stream of the production line and copolycondensed in the subsequent high-molecular part. The dosing of the glycol suspension of the modification components into the auxiliary reactor arranged in parallel with the production line is derived from the dosing of dimethyl terephthalate into the main line.

Description

The present invention provides a process for the continuous preparation of chemically modified polyester fibers.

Hitherto, chemically modified polyester fibers have not been produced in such a manner that the modifier component or multiple modifiers are fed to the production line as a continuous stream of a suspension or solution of the active substance or substances in ethylene glycol. a terephthalic acid diglycol ester and its oligomers passing through the production line. This method requires separate modification of the modifying components by esterifying the acidic groups with ethylene glycol so that the added modifying component does not affect the acidity of the mainstream reaction by slowing it down, reducing its conversion rate and leading to the formation of etheric compounds acting as undesired secondary modifiers Another possibility is a process for the continuous preparation of a copolyester by adding a melt of the modifier component polymer to the mainstream polycondensation melt into a polyethylene terephthalate melt. The disadvantage of this process is the separate production of the modifying copolymer concentrate on a separate device into the mainstream.

for the production of polyester with modification by means of multiple modifying components, combinations of the two processes are known, with one inlet of solution or suspension into the low molecular phase production and one inlet of copolymer melt into the high molecular phase before spinning the copolyester.

The disadvantages of the known processes for the continuous preparation of chemically modified polyester fibers are eliminated by the present invention, 2334505

2 is that the reaction of the modifiers with ethylene glycol takes place separately from the mainstream of the production line in a branched and low molecular phase process already part of the mainstream, whereby after the esterification of the modifiers is complete, the branched stream contains glycol esters modifying copolymers are recycled to the mainstream, which is then subjected to copolycondensation ·

Esterification of the modifying components with ethylene glycol in a branched mainstream, which consists of the diglycol ester of terephthalic acid and its oligomers, does not affect the course of the main reaction, since this is terminated at a given stage, so the acidity of the modifying components The modification components are mixed with the branched mainstream during the esterification process, resulting in better liquefaction, and can therefore be esterified with a lower excess of ethylene glycol and therefore at a higher temperature, resulting in a shortened esterification. In this case, the esterification time is readily adjustable by the size of the reactor auxiliary reactor within wide limits according to the technological requirements for the degree of conversion in the esterification of the modifying components. The above advantages lead to an improved production economy.

The process according to the invention can be applied to the existing continuously operating production lines without major machine modifications and allows the use of all known types of modifying agents such as isophthalic acid, 5-sulfoisophthalic acid, monosodium salt, polyethylene glycol and pentaerythritol. A further advantage of the process according to the invention is that it allows to combine the stream containing the modifying components with the mainstream of the production line under similar conditions and similar composition (temperature, free ethylene glycol content, catalyst content, conversion), enabling non-violent and economical production management. process. The advantage is also the possibility of changing the product range on the production line with a small outage of non-standard polyester. The fact that the esterification of the modification components with ethylene glycol is carried out at a higher temperature according to the invention makes it possible to reduce the need for the corresponding catalyst and hence the savings of auxiliaries and also the use of cheaper modification acids compared to the esters currently used. For example today. the dimethylisoctalate used can be replaced by isophthalic acid.

234 505

The following examples illustrate the method for the uninterrupted preparation of chemically modified polyester fibers according to the invention. Parts and percentages are by weight unless otherwise stated.

The continuous polyester fiber production line was operated by feeding fused dimethyl terephthalate at a rate of 394 kg / h and ethylene glycol together with catalysts at a total amount of 208 kg / hr to the continuous over-esterification reactor with indirect heating. from the top of the separation column above the reactor · The product discharged from the reactor had an average of 71% free ethylene glycol and its average degree of polymerization was 2.58 · a portion of this product at 200 kg / hr was fed to a dinyl-auxiliary heater cascade of seven consecutive chambers · A slurry of isophthalic acid and sodium 5-sulfoisophthalic acid in ethylene glycol at a rate of 66.30 kg / h was continuously fed into the first chamber of the auxiliary reactor by a gear pump. 7.25 kg / h. and the product from this reactor was combined with the remaining product from the transesterification reactor and entered the first polycondensation reactor of the production line. The analysis showed an esterification conversion of 98.6% (by acidification of the product) and an ether content expressed as a diethylene glycol concentration of 1.63%. . A modification slurry was prepared in a slurry mixer weighing 156.75 kg of 5-sulfoisophthalic acid monosodium salt, 402.45 kg of isophthalic acid, 435.30 kg of ethylene glycol and 0.04 kg of manganese acetate tetrahydrate. The product produced was polycondensated, with an average of 98 kg / h of ethylene glycol being drawn off, the amount of polymer produced being 432 kg / h.

Example 2

The production line carried out as in Example 1 was operated in such a way that 369.5 kg / h were fed into the transesterification reactor. dimethyl terephthalate and 210 kg / h of ethylene glycol together with catalysts · On average, 131.5 kg of methanol were withdrawn from the column head ·

- 4,234,505

The liquid product from the reactor branched into two streams, the first at 180 kg / h entering the first polycondensation reactor of a continuously operating production line, the second at about 188 kg / h ·. The isophthalic acid slurry in ethylene glycol containing 50% acid was continuously fed to the reactor by means of a gear pump.

59.2 kg / h The suspension was prepared in a separate slurry mixer by mixing 450 kg of isophthalic acid in 450 kg of ethylene glycol with the addition of 0.06 kg of manganese acetate tetrahydrate. On average, the withdrawal column of the auxiliary reactor was withdrawn

6.5 kg / h of water and 11.4 kg / h of ethylene glycol. The product from the auxiliary reactor showed an acidity below 0.003 mval / g and was continuously metered into the mainstream before entering the first Lycycondensation Reactor. The copolycondensation was then carried out in three successive reactors under reduced pressure. An average of 80 kg / h <ethylene glycol was withdrawn from the polycondensation reactors. From the direct spinning following the last oolocondensation reactor, 430 kg / h. in a known manner on a copolyester cable.

Example 3

The production line, as in Example 1, was operated such that 400.0 kg / h of fused dimethyl terephthalate and 223.0 kg / h of ethylene glycol were continuously fed into the transesterification reactor together with the catalyst. An average of 139.0 kg / h 'of methanol was taken off the top of the column. An amount of 200 kg / ha was withdrawn from the stream leaving the transesterification reactor and fed to the auxiliary reactor described in Example 1. Next to this feed stream, 31.85 kg / h of the slurry prepared in the slurry mixer was charged from the feed. . 676 kg of ethylene glycol, 400 kg of 5-sulfo-isophthalic acid monosodium salt and 0.025 kg of manganese acetate tetrahydrate. An average of 15.4 kg / h of ethylene glycol and 1.6 kg / h of water were continuously withdrawn from the separation column of the auxiliary reactor. The product from the auxiliary reactor was fed to the main stream at 252 ° C and was fed to the first polycondensation reactor. In the polycondensation section, an average of 89 kg / h of ethylene glycol was removed. The spun polymer at 430 kg / h 1 was processed into staple and cable. The sulfur content of the fiber was determined to be 0.31% ·

Claims (3)

234 505 Process for the continuous preparation of chemically modified polyester fibers, characterized in that from the low molecular weight part of the continuously operating polyethylene terephthalate production line a branch of 0.02 to 08 parts by weight of the main stream treated with modifying additives and a branched stream with additives is mixed. returns to mainstream. 2. A process according to claim 1, wherein the branched stream is the product of ethylene glycol interchangeable esterification of dimethyl terephthalate or esterification of terephthalate acid with ethylene glycol having a free ethylene glycol content by weight of 1 to 21 with a conversion input greater than 0 DEG /. ° C is taken from the section between the low molecular weight and the lycondensation part of the main line and the return flow is fed to the same part of the line from the point of collection of the product flow, the return flow does not differ by more than ethylene glycol. than 2Q conversions of more than 15 a and current temperatures do not differ and more than 50 ° C. 3. A process according to claim 1, wherein the branched stream is treated with isophthalic acid, sulfoisophthalic acid, derivatives or mixtures thereof, the latter being supplied in the form of a suspension or solution in ethylene glycol.