KR20070066552A - Method of preparing polyester resin having excellent transmittance - Google Patents

Abstract

A catalyst preparing method which maintains high transparency of a dissolved antimony catalyst without precipitation, and prevents the dissolved antimony catalyst from being precipitated, or prevents the polymerization reactivity of the dissolved antimony catalyst from being deteriorated even in case of a long storage period is provided. A method of preparing polyester resin comprises the steps of: (a) dissolving 0.3 to 1.5 weight part of an antimony-based compound into 100 weight parts of a diol compound; and (b) adding 5 to 30 weight parts of an acetic acid-based compound to the antimony-based compound dissolved solution. The antimony-based compound is selected from the group consisting of antimony trioxide, and antimony triacetate. The acetic acid-based compound is selected from the group consisting of acetic acid, acetic anhydride, ethyl acetate, methyl acetate, and mixtures thereof. The diol compound is selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, and polyglycols thereof.

Description

Method for preparing polyester resin having excellent transparency {Method of preparing polyester resin having excellent transmittance}

The present invention relates to a method for preparing a polymerization catalyst in which polyethylene terephthalate (PET) used as a raw material of a transparent packaging container has excellent optical transparency. More specifically, a method of using a certain additive so as to control the atmosphere of the catalyst solution prepared by dissolving in ethylene glycol (EG).

Since polyester has excellent mechanical strength, heat resistance, transparency and gas barrier property, polyester is most suitable as a material for beverage filling containers such as juices, soft drinks, carbonated drinks, packaging films, audio, and video films. Is being used.

It is also used in large quantities on a global scale as an industrial material for medical fibers and tire cords.

As a method of improving the heat resistance of a polyester bottle for beverage, a method has been proposed in which the bottle cap is heat treated to increase the crystallinity or heat-set the stretched bottle. In particular, when the crystallization of the plug portion is insufficient, or when the variation in the degree of crystallinity is large, the sealability with the plug may be deteriorated, and leakage of the contents may occur. In addition, when the degree of crystallinity of the shoulder and the body of the bottle is insufficient, thermal deformation may occur and product value may decrease.

Specifically, in the case of beverages requiring heat charging, such as juice drinks, oolong tea, mineral water, etc., a method of crystallizing by heat-treating the stopper of the preform or molded bottle (Japanese Patent Publication No. 55-79237) Japanese Patent Application Laid-Open No. 58-110221). In the case of heating and crystallizing the preform stopper in the amorphous state, the so-called spherical crystallization is promoted and the stopper appearance becomes white, but the crystallinity is increased to improve the heat resistance (that is, the heat deformation temperature is high). Moreover, in order to improve the heat resistance of a bottle trunk part, the method of heat-processing by making temperature of a stretch blow mold high temperature is employ | adopted (Japanese Patent Publication No. 59-6216).

When heat treatment is performed by contacting the shoulder and the body of the bottle obtained by stretching blow such a preform with a high temperature mold wall surface, in addition to the orientation crystallization by the stretching blow, the formation of microcrystals having a small crystal grain size is promoted, resulting in high crystallinity. The heat resistance of the bottle can be improved.

Such a method, that is, a method of heat-treating the plug portion and the shoulder portion to improve the heat resistance, preferably has a high crystallization rate PET that can be processed in a short time at low temperature due to the time of crystallization treatment and the temperature greatly affecting the productivity. Do. On the other hand, the trunk portion is required to be transparent even if the heat treatment during molding is performed in order not to deteriorate the color tone of the contents of the bottle, and in terms of designability, and the opposite characteristics are required at the stopper portion and the trunk portion.

In general, a catalyst solution prepared by dissolving while heating in ethylene glycol has a problem in that the solubility is lowered after a certain period of time or after a certain time in cooling at room temperature, so that the catalyst is precipitated and dissolves well even when heated again. Thus, the prepared catalyst solution has a risk of being maintained at a high temperature under continuous heating or warming conditions, and if a little precipitation occurs, it affects the transparency of PET and adversely affects the polymerization reactivity.

The present invention relates to a method for preparing a catalyst in which the dissolved antimony catalyst does not precipitate, maintains high transparency, and does not cause precipitation even when stored for a long time, and does not lower the polymerization reactivity.

In order to achieve the above object, the present invention is to prevent the production of antimony acid salt using a certain additive in the atmosphere of the catalyst solution is the configuration of the main invention. Here, the additives used are acetic acid-based compounds, such as acetic acid, acetic anhydride, ethyl acetate, methyl acetate, and the like, and in this embodiment, acetic acid is used. It was.

The catalyst composition for producing polyester according to the present invention is characterized in that it comprises 100 parts by weight of a diol compound, 0.3 to 1.5 parts by weight of antimony compound and 5 to 30 parts by weight of acetic acid compound.

Preferably, the antimony-based compound is characterized in that it is selected from the group consisting of antimony trioxide, antimony tri acetate.

Preferably, the acetic acid-based compound is selected from the group consisting of acetic acid, acetic anhydride, ethyl acetate, methyl acetate and mixtures thereof.

Preferably, the diol compound is selected from the group consisting of ethylene glycol, diethylene glycol (diethylene glycol), propylene glycol (propylene glycol), butylene glycol (polyglycol) thereof It is done.

Method for producing a catalyst for producing polyester according to the present invention,

a) dissolving 0.3-1.5 parts by weight of the antimony compound in 100 parts by weight of the diol compound; And

(b) adding 5 to 30 parts by weight to the solution in which the antimony compound is dissolved;

Characterized in that it comprises a.

The polyester resin according to the present invention is characterized in that it is prepared by the polycondensation reaction in the presence of the esterification reaction of the carboxylic acid component and the diol component and the catalyst according to claim 1.

Hereinafter, the present invention will be described in detail.

The antimony compounds used in the examples of the present invention are antimony trioxide and antimony triacetate, and ethylene glycol was used as a solvent to dissolve the catalyst. In addition, acetic acid was used as an additive to control the atmosphere of the catalyst solution. Acetic acid is a material that is also used to purify and wash terephthalate, a polymerization raw material of polyester, and has been selected because it is easily removed when subjected to high temperature polymerization. The catalyst solution prepared using acetic acid can polymerize polyester which is less precipitated and has more transparency than the unused catalyst solution even when left for a long time. When reheated and dissolved after precipitation, it can be dissolved again with increased solubility when added and dissolved.

Here, ethylene glycol, an antimony compound, and an additive can be prepared by throwing it in from the beginning. However, if the additives are prepared at a low temperature of 100 ° C. or less to prevent scattering, the reaction time is long because the solubility decreases. Therefore, the preparation of the catalyst with ethylene glycol and an antimony compound at a high temperature first and then cooling the additives is necessary. desirable.

The amount of the additive added is 5 to 30 parts by weight, preferably 10 to 20 parts by weight, based on mass based on the ethylene glycol used. If it is less than 5 parts by weight, the effect of controlling the atmosphere of the solution is minute, and if it exceeds 30 parts by weight, it is difficult to handle the solution due to a strong odor, and there is a problem in that sudden gas generation occurs when introduced into the polymerization reaction.

In this case, the amount of antimony-based compound used depends on the method and the amount to be added to the polymerization process, but for precise injection, it is generally prepared in an amount of 0.3 to 1.5 parts by weight based on ethylene glycol.

Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples. The following examples are intended to illustrate the present invention more specifically, but the scope of the present invention is not limited by the following examples.

Comparative Example 1

100 ml of ethylene glycol was added to the Erlenmeyer flask, and 0.71 g of antimony trioxide was added to mount the Erlenmeyer flask with a cooling condenser on a hot plate to dissolve the catalyst while maintaining an internal temperature of 120 占 폚 to prepare a catalyst solution.

200 g of terephthalic acid and 90 g of ethylene glycol were added to a three-necked circular flask reactor and stirred well to prepare a slurry. The slurry was stirred at 30 rpm while maintaining the internal temperature of 265 ° C. using a heating mantle. Then, nitrogen was introduced into the reactor to circulate nitrogen by allowing a certain amount of nitrogen to flow under pressurization of about 0.2 bar into the nitrogen atmosphere. The ester reaction was completed by using the end point of the reaction when water, which was a byproduct of the reaction, was no longer present.

After the ester reaction was completed, 100ppm of the antimony trioxide catalyst prepared above was added to the reactor, 0.1torr vacuum was slowly applied, and the condensation polymerization reaction was performed for 1 hour while maintaining the reactor internal temperature at 280 ° C. The polycondensation reaction was carried out while controlling the output of the stirrer in consideration of the decrease in the stirring speed according to the rise of the viscosity of the reactant as the reaction time elapsed, while maintaining the stirring speed at a constant 30rpm. The polycondensation reaction of which condensation polymerization was completed was quenched in a bath containing cold water to prepare polyethylene terephthalate (PET). After drying the prepared sample of polyethylene terephthalate well, a flat specimen of 2 millimeter thickness was measured by injection molding, and the whiteness and opacity were measured. .

Example 1

100 ml of ethylene glycol was added to the Erlenmeyer flask, and 0.71 g of antimony trioxide was added, and the Erlenmeyer flask was equipped with a cooling condenser on a hot plate to dissolve the catalyst while maintaining an internal temperature of 120 占 폚 to prepare a catalyst solution. After completion of the catalyst dissolution, the temperature was lowered to 50 ° C., and then 8 g of acetic acid was added thereto, followed by stirring for 1 hour.

Polymer polymerization was carried out according to the comparative example, and the same injection specimen was molded to measure the whiteness and opacity. In addition, the catalyst solution was checked for precipitation after 3 days.

Example 2

100 ml of ethylene glycol was added to the Erlenmeyer flask, and 0.71 g of antimony trioxide was added, and the Erlenmeyer flask was equipped with a cooling condenser on a hot plate to dissolve the catalyst while maintaining an internal temperature of 120 占 폚 to prepare a catalyst solution. After completion | finish of catalyst dissolution, it cooled to 50 degreeC, acetic acid 16g was added, and it stirred for 1 hour.

Polymer polymerization was carried out according to the comparative example described above, and whiteness and opacity were measured with the same injection specimen. In addition, the catalyst solution was checked for precipitation after 3 days.

Example 3

100 ml of ethylene glycol was added to the Erlenmeyer flask, and 0.71 g of antimony trioxide was added, and the Erlenmeyer flask was equipped with a cooling condenser on a hot plate to dissolve the catalyst while maintaining an internal temperature of 120 占 폚 to prepare a catalyst solution. After completion | finish of catalyst melt | dissolution, after temperature-falling at 50 degreeC, acetic acid 24g was added and it stirred for 1 hour.

Polymer polymerization was carried out according to the comparative example described above, and whiteness and opacity were measured with the same injection specimen. In addition, the catalyst solution was checked for precipitation after 3 days.

No. Color-L (whiteness) Specimen Opacity Catalyst precipitation Comparative Example 1 90.3 0.62 Example 1 92.7 0.43 △ Example 2 93.6 0.32 X Example 3 93.8 0.21 X

Table 1 shows that the examples polymerized using the catalyst preparation method used in the present invention had a brighter color and transparency than the comparative example not used, and also prevented catalyst precipitation.

As described above, the color and transparency of the polyester could not be controlled by the commonly used catalyst dissolution method. However, using the catalyst preparation mentioned in the present invention, color and transparency can be controlled to produce an optically excellent polyester resin.

Claims (9)

A catalyst composition for producing polyester, comprising 100 parts by weight of a diol compound, 0.3 to 1.5 parts by weight of an antimony compound, and 5 to 30 parts by weight of an acetic acid compound. The catalyst composition for producing polyester according to claim 1, wherein the antimony compound is selected from the group consisting of antimony trioxide and antimony tri acetate. The method of claim 1, wherein the acetate compound is selected from the group consisting of acetic acid (acetic acid), acetic anhydride (acetic anhydride), ethyl acetate (ethyl acetate), methyl acetate (methyl acetate) and mixtures thereof A catalyst composition for producing polyester. According to claim 1, wherein the diol compound is selected from the group consisting of ethylene glycol, diethylene glycol (diethylene glycol), propylene glycol (propylene glycol), butylene glycol (polyethylene) thereof Catalyst composition for producing polyester, characterized in that. (a) dissolving 0.3-1.5 parts by weight of the antimony compound in 100 parts by weight of the diol compound; And (b) adding 5 to 30 parts by weight to the solution in which the antimony compound is dissolved; Method for producing a catalyst for producing a polyester comprising a. The method of claim 5, wherein the antimony compound is selected from the group consisting of antimony trioxide and antimony tri acetate. The method of claim 5, wherein the acetic acid-based compound is selected from the group consisting of acetic acid, acetic anhydride, ethyl acetate, methyl acetate, and mixtures thereof. The catalyst composition for producing polyester according to claim 5, wherein the diol compound is selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, butylene glycol or polyglycols thereof. A polyester resin produced by a polycondensation reaction in the presence of an esterification reaction of a carboxylic acid component and a diol component and a catalyst according to claim 1.