KR0160479B1 - Process for preparing polyester - Google Patents

Abstract

None.

Description

How to prepare polyester

The present invention relates to a method for producing a polyester, in particular, in the case of melt spinning the polyester at a winding speed of 2,500m / min or more to minimize the generation of trimming in the spinning and stretching step to prepare a polyester suitable for high-speed spinning It is about a method.

In general, polyesters typified by polyethylene terephthalate have excellent physical and chemical properties, and thus are widely used for various applications, especially fibers. Polyester fibers are typically produced by melt spinning, stretching and thermal setting. In recent years, as the spinning technology has been advanced, the winding speed during melt spinning can be drastically increased from 1000 to 1500 m / min to 2000 m / min or more. Particularly oriented unstretched yarn obtained at a winding speed of 2500 to 4000 m / min is provided to the stretching and combusting process as it is, and its use continues to increase greatly to become the mainstream of the spinning technology.

On the other hand, ultra-fast spinning with a winding speed of 4000 m / min or more has also been tested, but such high-speed spinning has a drawback that the threading during spinning is more frequent and the additives of the final product are significantly lowered. In order to overcome this drawback, we are testing the optimization of spinning conditions (e.g., spinning temperature, cooling air volume, cooling wind temperature, etc.) and structural improvements of spinning barrels and spinning nozzles, but these methods are limited and extensive. No improvement can be expected.

As a result of repeating the investigation by the present inventors about the cause of the above problem, although polyester has a property which is hard to crystallize compared with polyethylene, a polyamide, etc., when the winding speed at the time of melt spinning becomes 2000 m / min or more, it radiates Molecular orientation occurs due to tension, and crystallization occurs with this, and although crystallization of the emitter is not sufficient, the crystallization proceeds greatly, and the above-mentioned problem occurs, and the winding speed is more than 4000 m / min. It turned out that it became more remarkable.

From these facts, polyesters with high orientation and low crystallization in high-speed spinning are continuously examined in terms of their crystallization and molecular orientation behavior, and various additives capable of suppressing crystallization during molecular orientation are found. It has been found that the addition of bisphenol-A or S has a significant effect during the preparation of the polyester, and the present invention has been reached as follows. That is, in the present invention, in preparing a polyester in which the main repeating unit is ethylene terephthalate, the polymerization reaction is carried out at the stage before the completion of the completion phase, so that the bisphenol-A or bisphenol-S or ester-forming derivative thereof is polyester. It is characterized by adding and reacting with 0.2 to 2.0 mol% with respect to the acid component which comprises.

The addition time of bisphenol-A, bisphenol-S or ester-forming derivatives thereof used in the present invention is not particularly limited, but from the time when the ester and / or transesterification reaction is substantially started, until the condensation reaction starts. It is convenient in the process to add in the step. In addition, in the addition amount of these, when the addition amount is too small, the crystallization inhibitory effect at the time of molecular orientation in this invention is not acquired, On the contrary, when too much, the softening point of the polyester obtained will become low and the color will deteriorate, manufacture of polyester It is preferable to set it as the range of 0.2-2.0 mol% with respect to the dicarboxylic acid used at the time.

In the method for producing polyester, terephthalic acid is esterified with ethylene glycol, thymethyl terephthalate is transesterified with ethylene glycol, or terephthalic acid is reacted with ethylene oxide to give a terephthalic glycol ester and / or its low What is necessary is just to use the method of obtaining a polymer, stirring and heating this under reduced pressure and carrying out polycondensation reaction.

The polyester used in the present invention is mainly a polyethylene terate using a terephthalic acid component and an ethylene glycol component, but a part of the dicarboxylic acid component or glycol component (15 mol% or less in total) is used to improve the physical properties of the polyester. The polyester substituted with another component may be sufficient as it. The polyester may also contain a small amount of various additives such as anti-inflammatory agents such as titanium oxides, dyeing agents, flame retardants, antistatic agents, hydrophilic agents, colorants, stabilizers and the like.

According to the present invention, the thread trimming during the spinning and stretching process at the time of high-speed spinning with a spinning speed of 3000 m / min or more is significantly reduced, the door process is stabilized, and the productivity is greatly improved.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited by the examples, and parts represent parts by weight.

[Examples 1-3, Comparative Examples 1-2]

As shown in Table 1, the polyester containing bisphenol-A sweet cattle (intrinsic viscosity 0.61 to 0.63) was discharged through the spinning nozzle at a spinning temperature of 285 ° C and discharged at 44.5g / min, and air at 15 ° C was flowed at 0.5m / min. Blown, cooled, concentrated and emulsified, then wound at a speed of 4000m / min to obtain undrawn yarn, which was drawn at a draw ratio of 1.332. Table 1 shows the rate of trimming at this time.

*) The trimming rate calculation is a percentage of the number of trimming dopings to the total number of dopings (333) based on 1,000 hours.

Elongation at trimming is the percentage of trimming at 3,000 strokes

*) In case of Comparative Example 2, the color of polyester is deteriorated (increased b value) and the melting point is difficult to be large.

[Examples 4 to 5 and Comparative Example 3]

Except for using a polyester containing bisphenol-S (intrinsic viscosity 0.56 ~ 0.60) instead of bisphenol-A and spinning and stretching under the same conditions as in Example 1, the results are shown in Table 2.

Examples 6 to 7 and Comparative Example 4

As shown in Table 3, the polyester containing the bisphenol-A unit (intrinsic viscosity 0.62 to 0.64) was discharged through the spinning nozzle at a spinning temperature of 285 ° C and a discharge amount of 42.5g / min, and air at 15 ° C was flowed at 0.5m / min. After blowing to cool, focused and emulsified, then wound at a speed of 6500m / min. Table 3 shows the incidence of trimming at this time.

Claims (1)

In preparing a polyester in which the main repeating unit is ethylene terephthalate, bisphenol-A or bisphenol-S at a point in time from substantially starting of esterification or transesterification to just before starting of polycondensation reaction. Or 0.2 mol to 2.0 mol% of these ester-forming derivatives with respect to the acid component constituting the polyester, and reacting.