KR980009308A - METHOD FOR PREPARING POLYETHYLENE TEREPHTHALATE - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to a method for producing polyethylene terephthalate having a high degree of polymerization, which can economically produce a polyethylene terephthalate having a high degree of polymerization, and a method for producing polyethylene terephthalate having a certain degree of molecular weight by using terephthalic acid as an acid component and melt polycondensing ethylene glycol as a diol component And then polymerizing it in a solid state to prepare a high polymerization degree polyethylene terephthalate, it is preferable that the particle size is 50-300 at any time up to the end of the polycondensation step in the monomer compounding step of the melt- By weight, based on the weight of the polyethylene terephthalate, of silica to prepare solid phase particles of polyethylene terephthalate, followed by solid-phase polymerization, to produce a high polymerization degree polyethylene terephthalate.

Description

METHOD FOR PREPARING POLYETHYLENE TEREPHTHALATE

TECHNICAL FIELD The present invention relates to a method for producing a high polymerization degree polyethylene terephthalate, particularly a method for economical production of a high degree of polymerization polyethylene terephthalate.

Polyethylene terephthalate is widely used in the fields of industrial materials such as films, containers and sheets because of its excellent moldability and physical properties. However, since its mechanical properties are highly dependent on the degree of polymerization of the base resin, it has high mechanical properties and heat resistance In order to be used as a resin suitable for the required container molding, it is most important to produce the polymer with high polymerization degree and economical. Condensation during melting, which is a universal production method of polyethylene terephthalate, has a limitation in the degree of polymerization to be achieved, and degradation of physical properties such as coloring of the polyurethane is caused even when the polymerization reaction is accompanied even for a long period of time.

Therefore, in order to produce polyethylene terephthalate having a high polymerization degree, it is first melt-polymerized by a usual method, then solidified by cooling, granulated and dried for a long time to crystallize, and then a temperature 20-60 ° C lower than the melting point of the polymer Thereby maintaining a high polymerization degree of polyethylene terephthalate

However, in the solid phase polymerization of polyethylene terephthalate, since the particles are fused to each other at the time of solid-phase polymerization, a large lump is formed. Therefore, in order to solve such a problem, the preliminary crystallization treatment must be performed in the pre- Therefore, it took a long time to obtain a polymer having a high polymerization degree, so a solution was required.

The present inventors have made efforts to solve such problems, and as a result, in the solid phase polymerization of polyethylene terephthalate, the present inventors have been able to omit the preliminary crystallization step of the solid state polymerization by adding the specific silica, thereby efficiently producing polyethylene terephthalate of high polymerization degree in a short time I invented a way to do it.

Hereinafter, the present invention will be described in more detail with reference to examples.

There are generally two methods for producing polyethylene terephthalate, one of which is a method of producing terephthalic acid and ethylene glycol as raw materials and the other is a method of producing ethylene terephthalate using ethylene oxide instead of ethylene glycol.

In the present invention, a method of preparing polyethylene terephthalate as a solid particle by melt-kneading two components of an electron and then subjecting it to a heat polymerization treatment in a solid state to produce a high polymerization degree polyethylene terephthalate.

In the production of polyethylene terephthalate having such a high polymerization degree, in the present invention, 0.01 to 0.01 wt.% Of the weight of polyethylene terephthalate prepared as the final product at any time from the monomer compounding stage to the end of the polycondensation stage during the melt- -1.0% by weight of silica is added and uniformly dispersed. Subsequently, the solid phase polymerization reaction is carried out so that 0.01-1.0% by weight of silica is added to the polyethylene tereftthereof with a high degree of polymerization and uniformly dispersed. The polyethylene terephthalate of high polymerization degree could be economically obtained in a short time.

The size of the silica particles used in the present invention is preferably 50-300 nm, more preferably 50-100 nm. When the particle size is less than 50 nm, the particles are not uniformly dispersed. When the particle size is more than 300 nm, there is no effect of eliminating the foreign matter phenomenon and the pre-crystallization process in the solid particles produced after the melt polymerization.

In addition, the content of silica added in preparing the polyethylene terephthalate of high polymerization degree according to the present invention is preferably 0.01-1.0 wt%, more preferably 0.05-0.5 wt%, based on the weight of the polyethylene terephthalate. When the amount of silica to be added is less than 0.01% by weight, solid-state particles are fused to each other during solid-state polymerization, resulting in a large lump and no effect of omitting the preliminary crystallization step. When the amount of silica exceeds 1.0% After the melt polymerization, silica particles aggregate in the immobilized solid particles.

In the present invention, the addition timing of the silica may be added at any time from the monomer blending step to the end of the polycondensation during the melt-condensation polymerization, but it is preferable to add the monomer at the time of monomer combination or before the end of the esterification reaction.

In addition, it can be considered to mix the solid particles prepared after the melt polymerization and the silica particles by a compounding method, but it is not preferable because uniform silica dispersion is difficult and a foreign matter phenomenon appears.

As described above, according to the method of producing polyethylene terephthalate of high polymerization degree according to the present invention, even when the preliminary treatment process of the crystallization process is omitted in the high polymerization of polyethylene terephthalate, Can be efficiently obtained, simplifying the process, shortening the polymerization time, and the like. Therefore, the process is more economical than the conventional process for producing a polymer.

[Example 1]

858.5 gr of terephthalic acid, 323.9 gr of ethylene glycol, 0.1134 gr of zinc acetate hydrate, and 0.1 gr of silica having a particle size of 100 nm were put into an esterification reactor and stirring was started while the temperature was raised to 250 ° C under normal pressure. At this time, water as a by-product is removed, and if the amount of water to be discharged exceeds 90% by weight of the theoretical amount, it is transferred to a polymerization reactor, and 0.4519 gr of antimony trioxide is added and then the pressure is reduced to 0.1 Torr over 1 hour while the temperature is raised to 285 ° C . In this state, stirring is continued for 3.0 hours, stirring is stopped, and the melt is pushed out of the reactor into a certain strand by pressurizing with nitrogen, and the solid is cut into solid particles of 2x3 mm size while cooling with water.

And the cut solid particles directly removes surface adhesion water by hot air. Subsequently, the solid particles were put into a solid-state polymerization reactor and subjected to solid phase polymerization for 10 hours while being maintained at 220 占 폚. Table 1 shows the intrinsic viscosity of the solid particles condensed during melting and the solid particles having undergone solid phase polymerization and the fusion state of solid particles during solid phase polymerization.

[Example 2]

The procedure of Example 1 was repeated except that 10 g of silica having a particle size of 100 nm was added. The results are shown in Table 1.

[Example 3]

The procedure of Example 1 was repeated except that 0.5 g of silica having a particle size of 500 nm was added. The results are shown in Table 1.

[Example 4]

Except that 5 g of silica having a particle size of 300 nm was added. The results are shown in Table 1. The results are shown in Table 1. < tb > < TABLE >

[Comparative Example 1]

The results are shown in Table 1. The results are shown in Table 1. < tb > < TABLE >

[Comparative Example 2]

The procedure of Example 1 was repeated except that 0.05 g of silica having a particle size of 100 nm was added. The results are shown in Table 1.

[Comparative Example 3]

The procedure of Example 1 was repeated except that 15 g of silica having a particle size of 100 nm was added. The results are shown in Table 1.

[Comparative Example 4]

The procedure of Example 1 was repeated except that 15 g of silica having a particle size of 30 nm was added, and the results are shown in Table 1.

[Comparative Example 5]

The procedure of Example 1 was repeated except that 10 g of silica having a particle size of 400 nm was added. The results are shown in Table 1.

[Comparative Example 6]

10 g of a solid obtained by melt polymerization in the same manner as in Example 1 and 10 g of silica having a particle size of 50 nm were added thereto without adding silica and mixed with a compounding equipment. Then, the mixture was put into a solid-state reaction vessel and solid- . Table 1 shows the intrinsic viscosity of the solid particles and the state of fusion of the solid particles during the solid phase polymerization when the solid phase polymerization with the solid particles condensed during melting was completed.

In the present invention, the mixture of carbon tetrachloride and phenol in a ratio of 6: 4 was measured at 25 DEG C using a solvent.

[Table 1]

In the examples and comparative examples, the number of particles having a particle size of 1000 nm or more was measured by observing a film having a size of 1 cm in width and 1 cm in length using an optical microscope. When the number of particles was 4 or more, Three were judged to be normal and one or less were judged to be good.

Claims (3)

A method for producing polyethylene terephthalate obtained by melt polycondensing terephthalic acid and ethylene glycol with solid particles of a predetermined size and then polymerizing the solid particles to obtain polyethylene terephthalate having a high degree of polymerization, Wherein the solid phase particles of polyethylene terephthalate are prepared by adding silica at an arbitrary point in time to the end of the polycondensation step, followed by a high polymerization. The method according to claim 1, wherein the size of the silica particles is 50-300 nm. The method of producing a high-polymerization polyethylene terephthalate according to claim 1, wherein the silica is added in an amount of 0.01-1.0 wt% based on the weight of the polyethylene terephthalate. ※ Note: It is disclosed by the contents of the first application.