KR0122003B1 - Method for manufacturing polyester - Google Patents

Abstract

In producing a linear polyester polycondensating glycolester of aromatic dicarboxylic acid and/or this lower molecular weight condensate, the present invention relates to process for preparing high quality polyethyleneterephthalate in a short reaction time, which has a high melting point and excellent color tone and low terminal carboxyl and diethylene glycol content which comprise under the polycondensation catalyst, reacting antimonous compound as a polycondensation catalyst which obtained from reacting antimonous compound of antimony halide, antimony carboxylate antimony alkoxide etc. and mixture of 2,4-bis(alkoxycarbonyl)-1,5- benzendicarboxylate and 2,5-bis(alkoxycarbonyl)-1,4-benzendicarboxylate as a main component obtained by treating a reaction product of pyromeliticacid or pyromelitic anhydrous and alcohol with base.

Description

Production method of polyester

The present invention relates to a method for preparing a linear high-polymerization polyester by polycondensing a glycol ester of aromatic dicarboxylic acid and / or a low molecular weight condensate thereof, wherein the reaction product of pyromellitic anhydride and glycol is used as a base. A mixture wherein the main components obtained by treatment are 2,4-bis (alkoxycarbonyl) -1,5-benzenedicarboxylate and 2,5-bis (alkoxycarbonyl) -1,4-benzenedicarboxylate (hereinafter A method of obtaining a polyester having high melting point and excellent color in a short reaction time using a polycondensation catalyst as a polycondensation catalyst obtained from the reaction of an esterified pyromellitate salt) and an antimony compound. .

Polyesters currently produced industrially, especially polyethylene terephthalates obtained from aromatic dicarboxylic acids and glycols, have excellent mechanical and physical chemical properties and are widely used in textiles, films and other molding products. As a method, usually, terephthalic acid and ethylene glycol are heated to a reaction temperature of 200 to 280 ° C. under atmospheric pressure or pressure, and professional esterification or dimethyl terephthalate and ethylene glycol are heated to a reaction temperature of 140 to 240 ° C. in the presence of a catalyst. Bis (beta-hydroxyethyl) terephthalate and / or their low molecular weight condensates (hereinafter referred to as esterified products) obtained by the reaction are successively heated to a reaction temperature of 260 to 300 ° C. together with a polycondensation catalyst under high vacuum to polycondensation. Method to combine (hereinafter TPA method and DMT method And it is made of).

In the production of polyester on a commercial scale, polycondensation reaction catalysts are generally used to facilitate the polycondensation reaction. Such catalysts include metal compounds such as antimony, titanium, germanium, tin, zinc, manganese, and lead. It is well known that, depending on the type of catalysts used, the polycondensation kinetics and the quality of the resulting polyester are greatly influenced.

These polycondensation reactions are carried out for a long time at a high temperature in the presence of a metal compound catalyst, these catalysts easily obtain a high degree of polymerization of polyester, but there is a problem that the resulting polymer is colored with yellow or gray, accompanied by various unwanted side reactions When the content of diethyl glycol (DEG) and terminal carboxyl group (COOH) is increased to an appropriate level or more, there is a problem of deterioration of physical properties such as melting point and strength of the resulting polyester.

Therefore, a method of producing polyester having good color and excellent physical properties for a short polycondensation time is very important in terms of productivity and quality.

In view of these considerations, polycondensation catalysts currently used most industrially are antimony compounds and germanium compounds, especially antimony trioxide and germanium dioxide.

Antimony trioxide has a good price, relatively high catalytic activity during polycondensation, and excellent thermal stability, which is not a serious side reaction, but it is difficult to dissolve in ethylene glycol or reaction mixtures and tends to precipitate during the reaction. The esters have a problem of being colored yellowish green or gray or of poor transparency, and germanium dioxide has less side reaction activity, but the activity as a polycondensation catalyst is lower than antimony trioxide, resulting in a long polycondensation reaction time.

Coloring and side reactions adversely affect the quality of the resulting polyesters, so be very careful, but increasing the amount of catalyst or increasing the reaction temperature to increase productivity, ie to shorten the polycondensation reaction time, becomes more pronounced. .

Conventionally, various methods for shortening the reaction time as a catalyst or producing a polyester having excellent color and physical properties have been proposed in order to improve the problem of the double-sided property, but it is difficult to find satisfactory.

For example, first, as a method of increasing the polycondensation reaction rate, a method of reacting a silicon compound with a titanium compound (US Patent No. 3,927,052) and a method of using a germanium compound and a titanium compound together (British Patent No. 949,085) , Antimony trioxide, cobalt compounds and phosphorus compounds are dissolved in ethylene glycol and used (Japanese Patent Laid-Open No. 53-51295), and reaction products using titanium compounds and organic acids (US Pat. No. 4,131,601) Although known, the color of the polymer produced is colored pale yellow or the content of diethylene glycol or terminal carboxyl groups is increased, which causes many problems in the physical properties of the resulting polyester.

Second, a method of improving the color of the polymer using a cobalt compound as a color improving agent, that is, using a cobalt compound in combination with a titanium compound (Japanese Patent Publication No. 47-28119), cobalt compound in a mixed catalyst of antimony and tin (Japanese Patent Application Laid-Open No. Hei 2-73827) and a method of using a cobalt compound and an alkali metal compound together in an antimony compound (Japanese Patent Application Laid-Open No. 58-117216), etc. are known. Color, transparency and physical properties do not improve at the same time.

As described above, many studies have been carried out to solve the reason why it is difficult to simultaneously satisfy the shortening of the reaction time and improvement of coloring and property degradation due to side reaction, and to manufacture high quality polyester with high productivity. The purpose of this study is to reduce the reaction time and to provide excellent color and other physical properties of the polymer.

Thus, the inventors of the present invention have reached the present invention as a result of diligent research to prepare high-quality polyesters having high color, low dimethylene glycol content, low terminal carboxyl group concentration, and high melting point while shortening the polycondensation reaction time.

That is, the present invention directly esterifies a terephthalic acid or dicarboxylic acid and derivatives thereof, and ethylene glycol or glycols and derivatives thereof, or dimethyl terephthalate or dialkyl terephthalate thereof as a main component. And transesterification of the isomers or derivatives thereof with ethylene glycol or glycols thereof and derivatives thereof to obtain esterified products having bis (beta-hydroxyethyl) terephthalate and / or low molecular weight condensates thereof as the main component. When polycondensation is carried out to prepare polyester, a precondensation antimony compound which is a reaction product of esterified pyromellitate salt and antimony compound obtained by treating the reaction product of pyromellitic anhydride and glycol with a base is used as a polycondensation catalyst. Characterized by using In addition, these preliminary antimony compounds could substantially overcome the two-sidedness of the above-described shortening of the reaction time and consequent intensification of side reactions.

Therefore, one object of the present invention is to produce a high quality polyester having a high melting point and excellent color tone, and another object is to provide a method for producing a polyester having high productivity through a short reaction time.

In more detail, the method for achieving these objects will be described as terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, diphenyl-4, 4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, Aromatics such as diphenoxy-ethane-4,4'-dicarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelinic acid, sebacic acid, cyclohexanedicarboxylic acid, decarinic dicarboxylic acid and the like, Aliphatic and cycloaliphatic dicarboxylic acids and ester derivatives such as methyl esters, ethyl esters and phenyl ester compounds of these acids, and examples of the glycol component include ethylene glycol, trimethyl glycol, tetramethylene glycol, hexamethyl glycol and cyclohexane- 1,4-dimethanol, 1,4-cyclohexanediol, Aliphatic, cycloaliphatic and aromatic diols such as bisphenol A, bisphenol S, bishydroxyethoxy bisphenol A, tetrabromobisphenol A, and the like; trimellitic acid, tramesic acid, pyromellitic acid, trimethylolpropane, glycerin And polyfunctional crosslinking agent compounds such as pentaerythritol and the like, and monofunctional end group terminators such as monomethoxy polyethylene glycol, stearyl alcohol, palmitic acid, benzoic acid, naphthoic acid and the like can be added.

Among the compounds exemplified above, the present invention relates to a case in which a polyester is prepared by reacting a dicarboxylic acid or an ester derivative thereof having a main component of dimethyl terephthalate, which is a terephthalic acid or a methyl ester derivative thereof, with ethylene glycol or a diol thereof. It is also very effective and effective in producing copolyesters containing at least one third component in addition to these main components, but the content of the third component should not exceed 40 mol%.

Glycol esters of aromatic dicarboxylic acids, i.e., bis (beta-hydroxyethyl) terephthalate and / or low molecular weight condensates thereof (polymerization degrees 2 to 10) can be used for the direct esterification of aromatic dicarboxylic acids and glycols, From lower alcohols (1-4 carbon atoms) of dicarboxylic acids or transesterification of phenyl esters and glycols, or reactions with ester-forming derivatives of glycols such as 1,2-epoxides of aromatic dicarboxylic acids and glycols Can be obtained.

Glycol esters or low-molecular-weight condensates thereof are polycondensation reaction catalysts containing preliminary antimony compounds as the main component when preparing polyesters by successively polycondensing them from esterified products consisting of esterification catalysts or transesterification catalysts. Thus, as described above, this is the main product of the reaction between the antimony compound and the pyromellitate esterified by the main component.

Here, the antimony compound may be represented by the structural formula (I), and as a specific example

Antimony halides such as antimony trichloride, antimony tribromide and antimony trifluoride, and antimontriacetate, antimonttristearate, antimontribenzoate, antimontri 2-ethyleneglycoside, antimontriisopropoxide, antimontri n-butoxide Antimony alkoxide compounds, such as a side and anthritriphenol side, etc. can be mentioned, Especially, Halogenated antimony, such as antimony trichloride, is preferable.

The esterified pyromellitate salt can also be represented by the formula (II),

Expression from M ⁺ ₂ is an alkali metal cation, ammonium or an organic amine cation such as trimethylammonium, triethylammonium, such as lithium, sodium, potassium, M ⁺⁺ denotes an alkaline earth metal cations such as magnesium and calcium, R Represents an aliphatic or alicyclic alkylene, an aromatic aryl group, or a derivative thereof.

For example R is methyl ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-amine, acetylisopropyl, neohexyl, isohexyl, n-hexyl, heptyl, octyl, decyl, Dodecyl, octadecyl, cyclopentyl, cyclohexyl, phenyl or benzyl groups are mentioned, especially alkyl groups having 1 to 18 carbon atoms.

First, the pyromellitic acid esterified by the formula (II) is esterified from pyromellitic acid and glycol in the presence of a catalyst or the main component esterified by ring-opening reaction of anhydride groups from pyromellitic anhydride and glycol. By treating the diesterized pyromellitic acid, an ester derivative, with a metal hydroxide or an organic base to prepare a carboxylate thereof, an alcohol component (for example, methanol) bound to the ester group is used as a reactant and a solvent, without being used separately in the reaction solvent. Used as.

When the diesterized pyromellitic acid was prepared and then converted into a metal carboxylate, the higher the alcohol molecular weight, ie, the smaller the polarity of the solvent, the lower the solubility of the metal oxide, so that distilled water had to be added to the reaction mixture.

The esterified pyromellitate salt thus obtained is reacted with the antimony compound as described above without being separated to produce a preliminary antimony compound used as a polycondensation catalyst in the present invention. The reaction product is precipitated in the precipitant, and the powder obtained by recovery, washing and drying is used in the production of polyester in the form of a slurry dispersed in ethylene glycol or in a dissolved solution.

Ethylene glycol is preferred as an alcohol component in the esterification process, which is the first step in the preparation of the above-described antimony compound, and as a esterification method, a method of heating pyromitylic anhydride and an alcohol component together is preferred. In the conversion to esterified pyromellitate), alkali metal hydroxides such as lithium were preferred as bases, and antimony compounds such as antimony trichloride were preferred as antimony compounds in the third step of preparing an antimony compound.

Preliminary antimony compounds obtained in this way are among the unsubstituted groups (e.g., chlorine of antimony trichloride) and diesterized pyromellitate salts of antimony metals and antimony compounds according to reaction conditions such as reaction time, reaction scale, reaction temperature and reaction molar ratio. There may be a difference in the content of the unsubstituted metal (eg, lithium metal of the diesterized lithium dicarboxylate), and may also exist as a hydrate.

For example, the process of preparing a precondensation antimony compound as a polycondensation catalyst will be described in more detail.The reaction of pyromellitic anhydride and excess methanol to the boiling point of the metaol and reacting for about 0.5 to 2 hours results in a clear solution. Depending on the attack position, a mixture of 2,4-bis (alkoxycarbonyl) -1,5-benzenecarboxylic acid and 2,5-bis (alkoxycarbonyl) -1,4-benzenedicarboxylic acid as the main product When a metal hydroxide such as lithium hydroxide is added to the reaction mixture continuously without separating them, an esterified lithium pyromellitate salt in which M ⁺⁺ of Structural Formula (II) is Li is obtained.

Then, without separating it, an antimony compound such as antimony trichloride was directly dissolved in the reaction mixture outside of methanol used as a reaction solvent, and added at room temperature to precipitate immediately. The reaction mixture was sufficiently stirred and poured into excess acetone. Leave for one night, strain, wash again with acetone several times and dry well.

In order to confirm the reaction progress of each reaction process, the infrared spectrum of the reaction product was removed for each reaction process in which the solvent was removed. The anhydride of pyromellitic anhydride, which is a starting material in the first reaction between pyromellitic anhydride and methanol, was obtained. Infrared absorption peaks by groups showed double absorption peaks at 1858 and 1770 cm ^_1 , but the infrared spectrum of esterified pyromellitic acid, a reaction product with methanol, showed that the absorption peaks by anhydride groups disappeared and methoxycarbonyl groups at 1743 cm ^_1 . An absorption peak attributable to the methyl ester group and an absorption peak attributable to the carboxylic acid group at 1702 cm ^_1 were observed.

The esterification by a dicarboxylic acid is the infrared spectrum of which esterification lithium pyromellitic acid chloride with lithium hydroxide absorption peak of the methyl ester group has been moved to the 1580㎝ ^_1. In addition, in the infrared spectrum of a pre-antimony compound, which is a reaction product of esterified lithium pyromellitate and antimony trichloride, methoxycarbonyl ester according to the reaction conditions such as the molar ratio between these compounds, the scale of the reaction, and the concentration of the reactant to the reaction solvent. The absorption peak of the group was observed between 1700 ~ 1725 cm ^_1 .

Conventional antimony compounds, especially those currently used in the production of polyester on a commercial scale, are often used in the field of antimony trioxide, which is precipitated when dissolved in ethylene glycol and left at room temperature for a long time. When contacted with acetic acid is liberated by the hydrolysis reaction and the smell is severe and the stability of the catalyst is lacking, but the preliminary antimony compound of the present invention is a solid in the form of powder, so there is little risk of deterioration even in long-term storage, about 120 ℃ in ethylene glycol The above temperature is characterized by showing a solubility of at least 5% by weight or more, the addition of a small amount of tetraethylammonium hydroxide to ethylene glycol has the advantage of obtaining a solubility of at least 5% by weight at room temperature.

Currently, it is widely used all over the world, and is widely used in the polystyrene polycondensation catalyst. Antimony triacid is usually added to the reaction system by dispersing it in ethylene glycol at 5 to 10% by weight, but the catalyst particles are homogeneously dispersed and dissolved in the reaction examples. If the induction period can be reduced, the polycondensation reaction time can be reduced. For this purpose, if the polycondensation catalyst is homogeneously dissolved in ethylene glycol and introduced into the reaction system, the catalyst activity can be effectively expressed immediately at the molecular level. Since the polycondensation reaction time can be shortened, the fact that the polycondensation catalyst is dissolved in ethylene glycol is very important.

From this fact, the excellent solubility of the preliminary antimony compound of the present invention in ethylene glycol makes it possible to shorten the polycondensation time.

In addition, the preliminary antimony compound of the present invention showed excellent activity as a polycondensation catalyst in either ethylene glycol solution state or slurry state, and during the addition time, the DMT method can be used during or after transesterification reaction to avoid coarse particle formation. It is most advantageous to add after the transesterification reaction.

The antimony compound of the present invention is obtained by reacting a partially esterified pyromellitate salt represented by the formula (II) with an antimony compound such as antimony trichloride, and the molar ratio of pyromellitic anhydride and antimony compound is pyromellitic acid. 0.25-1 mol of antimony compound was good with respect to 1 mol of anhydrides.

In addition, the usage amount of the preliminary antimony compound catalyst need not be particularly limited, but may have sufficient activity depending on the reaction vessel.

In other words, the amount of the antimony compound used is usually 50-1,500 ppm and 80-1,000 ppm is better with respect to the finally obtained polyester polymer.

If the catalyst content is too small and the antimony metal content is less than 50 ppm, it is difficult to obtain a high degree of polymerization of the polyester polycondensate, and even if the catalyst content is used too much, there is almost no problem of physical properties and coloring of the polyester, but shortening of the polycondensation time It was dependent on the rate of removal of the glycol component produced during the reaction.

In the present invention, half or a part of the preparation of antimony antimony compound is an antimony compound such as antimony trioxide, a germanium compound such as germanium dioxide and germanium tetraethoxide, a manganese compound such as manganese acetate, and a zinc compound such as zinc acetate. It can be replaced if the substantial effect of it can be maintained.

In the present invention, polyesters can be prepared from conventionally known polycondensation reactions from glycol esters of aromatic dicarboxylic acids and / or low molecular weight condensates thereof.

For example, about 1 to 4 hours of ethylene glycol in the presence of a transesterification catalyst such as magnesium acetate is heated at a reaction temperature of 130 to 250 ° C. in the presence of atmospheric pressure vessel for about 1 to 4 hours with respect to the dialkyl terephthalate and the dialkyl terephthalate. Bis (beta-hydroxyethyl) terephthalate and its low molecular weight condensate were prepared by a transesterification reaction to remove lower alcohol during the process (ester exchange reaction), and then the reaction temperature was 260-300 ° C. in the presence of the polycondensation catalyst. Polyethylene condensation reaction was carried out while removing the produced ethylene glycol under a reduced pressure of 01 to 30 Torr for 1 to 5 hours to obtain polyethylene terephthalate, or by heating terephthalic acid and ethylene glycol to 200 to 280 ° C under atmospheric pressure or pressure. Bis (beta-hydroxy) through a direct esterification reaction that removes the resulting water for about 1 to 4 hours. Cyethyl) terephthalate and / or its low molecular weight condensate is prepared and then polyethylene terephthalate is obtained in the presence of the above examples and the polycondensation catalyst.

In preparing the polyester in this manner, in the present invention, in addition to the above-mentioned multifunctional crosslinking agent and monofunctional terminal self-locking agent, colorants such as carbon black, pigments, dyes, matting agents such as titanium dioxide, phosphorus compounds, ultraviolet absorbers, and oxidation Inhibitors, diethylene glycol production inhibitors such as lithium acetate or sodium acetate, flame retardants, nucleating agents such as silica or alumina, fluorescent whitening and antistatic agents can be added to the reaction mixture at any stage of the reaction process.

Herein, the phosphorus compound is a thermal stabilizer which is commonly added in the production of polyester, for example, phosphoric acid, phosphorous acid, metaphosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, trioctyl phosphate, dimethyl phosphite and diethyl phosphate. Pit, triphenyl phosphite, dioctyl phosphite, trimethyl phosphite, triethyl phosphite, triphenyl phosphite and the like, and antioxidants are higandphenols of the Iganox series from Ciba-Geigy, Switzerland, for example. For example, Iganox 1010, Iganox 1222, Iganox 1076, Iganox 1098, etc. are mentioned.

As described above, according to the present invention, it is possible to shorten the polycondensation reaction time during the preparation of polyester compared with the conventional method, and the color of the obtained polymer is very excellent, the melting point is high, and the diethylene glycol content and the terminal carboxyl group The present invention provides a method for producing a high-quality polyester having a low concentration using the catalyst of the present invention, and the polycondensation catalyst is very stable even for a long time storage so that it can be conveniently handled in the manufacturing process.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by Examples.

In addition, in the examples, "parts" means "parts by weight" and "reaction time" means a polycondensation reaction time from the normal pressure of the polycondensation reactor to the end of the reaction under high vacuum except for the high vacuum decompression time (60 minutes) of 0.8 to 0.9 Torr. And the various physical properties mentioned in the examples are obtained and defined as follows.

1. Ultimate viscosity [η]

Intrinsic viscosity [η] is obtained by using a Canon-Penske viscometer at 25 ° C. with an ortho-chlorophenol solution.

2. Color

The color of the obtained polyester is represented by L and b values, and these values are condensed using a color difference meter, and then the polymerized polyester is extruded into cooling water through a nozzle at the bottom of the reactor to obtain a spaghetti, and then chips obtained at regular intervals are obtained. The L and b values obtained here are indicative of the brightness of the polymer and the degree of coloring to yellow, respectively, and indicate that the color is better as the L value is smaller and the b value is smaller.

3. Concentration of Terminal Carboxyl (COOH)

The resultant polyester chip was dried in a vacuum oven at 60 ° C. under a reduced pressure of 1 Torr or less for 3 hours, and then dissolved by heating at a concentration of 4 g / ㎗ ortho-cresol at about 100 ° C. with a 0.04N aqueous sodium hydroxide solution. The concentration of the terminal carboxyl group is obtained.

4. Melting point

The melting point of the obtained polyester was obtained by a DSC 7 series differential scanning calorimetry manufactured by Perkin-Elmer, and as a specific method thereof, the specimen was dried to about 10 mg after drying the polyester chip as in the terminal carboxyl concentration measurement method of the above item 3. After cutting, the sample was placed in an aluminum sample pan and rapidly heated to 280 ° C. and maintained for 7 minutes. Then, the resultant was quenched to 70 ° C. using a coolant, and then measured at an elevated temperature scanning rate of 20 ° C./min from room temperature to 300 ° C. The temperature of the endothermic peak peak on the thermogram of the differential scanning calorimeter was defined as the melting point.

5. Diethylene Glycol (DEG) Content

The obtained polyester chip was dried in the terminal carboxyl group concentration measurement example of the above 3, 1 g of the sample was taken, and heated with an external temperature of 210 ° C. for 3 hours in a sealed container of about 40 ml in the presence of a small amount of zinc acetate catalyst with 30 ml of methanol. Measured by chromatography.

The content of DEG is closely related to the melting point, so the smaller the content, the higher the melting point.

Example 1-4

A. Preparation of Polycondensation Catalyst

17.45 parts (0.08 mole) of pyromellitic dianhydride and 130 parts of methanol are put together in a round flask, heated to a boiling point and stirred at reflux for 5 hours, and the reaction mixture is cooled at room temperature, and lithium hydroxide monohydrate is externally added to the reaction mixture. 50 parts of distilled water was added sequentially and stirred well for about 30 minutes on a cold water bath.

6.08 parts (0.027 mole) of antimony trichloride externally was added to the reaction mixture obtained at room temperature, and a precipitate was formed immediately. The reaction mixture was stirred for about 30 minutes more, poured into an excess of acetone, left for one night, and filtered, After washing the reaction product again with acetone well and dried in a vacuum oven at about 68 ℃ under reduced pressure overnight.

According to the infrared spectrum, the absorption peak of the methyl ester group was observed at 1712 cm ^_1 , and the elemental analysis showed that the antimony metal content was 54.50 wt% and the lithium metal content was 5960 ppm.

B. Preparation of Polyester

800 parts of dimethyl terephthalate, 500 parts of ethylene glycol and 1.057 parts of magnesium acetate tetrahydrate were added to a reaction vessel with a stirrer and a rectifying tube, and heated by dissolving dimethyl terephthalate and starting stirring at about 140 ° C. Is generated.

When methanol is removed for 130 ~ 140 minutes and the reaction temperature is raised to 230 ℃ and 260 parts of methanol is removed from the reaction vessel, 5.36 parts of trimethyl phosphate dissolved in ethylene glycol at 10% by weight is added and stirred for 10 minutes. The prepared catalyst was dissolved in ethylene glycol at 5% by weight at about 100 ° C. with an antimony metal content of 119 to 954 ppm and finally stirred for about 10 minutes. While gradually warming up to ℃ and gradually depressurizing over 60 minutes to finally achieve a high vacuum of 0.8 ~ 0.9 Torr.

Subsequently, the polycondensation reaction was carried out under high vacuum to terminate the reaction, and the reaction was terminated and extruded into cooling water through a nozzle at the bottom of the reactor to form a spaghetti, which was then cut at regular intervals to obtain a polymer in a chip state.

Table 1 shows the polymerization time and the polyester properties obtained for each polycondensation catalyst content.

Example 5

A. Preparation of Polycondensation Catalyst

A polymerization catalyst was prepared in the same manner as described in section A of Examples 1 to 4, but a solution in which 12.32 parts (0.54 mole) of antimony trichloride was dissolved in 30 parts of methanol was used.

According to the infrared spectrum, an absorption peak attributable to methyl ester was observed at 1709 cm ^_1 . The elemental analysis showed that the antimony content was 52.85 wt% and the lithium content was 8720 ppm.

B. Preparation of Polyester

To prepare a polyester in the same manner as described in paragraph B of Examples 1 to 4, the polycondensation catalyst obtained in Section A is 5 weight to the antimony metal content of 240ppm to the polyester finally obtained as shown in Table 1 % Was added in the form of a slurry dispersed in ethylene glycol.

Table 1 shows the polycondensation reaction time and the physical properties of the obtained polyester according to the content of the catalyst.

[Comparative Examples 1-5]

To prepare a polyester in the same manner as described in B of Examples 1 to 4, but 5 to the antimony metal content of 92 ~ 735 ppm with respect to the polyester finally obtained as a polycondensation catalyst antimony trioxide as shown in Table 1 It was added in the form of a slurry dispersed in ethylene glycol by weight%.

Table 1 shows the polycondensation reaction time and the physical properties of the obtained polyester according to the content of the catalyst.

Comparative Example 6

To prepare a polyester in the same manner as described in B of Examples 1 to 4, the same amount of the polycondensation catalyst and the antimony trioxide catalyst obtained by the method of A of Examples 1 to 4 based on the antimony content Each of the polyesters finally taken out was added in the form of a slurry dispersed at room temperature at 5% by weight in ethylene glycol so that the total antimony metal content from each catalyst was 184 ppm.

The polycondensation reaction time and the physical properties of the obtained polyester are shown in Table 1.

Example 6

A slurry consisting of 556 parts of terephthalic acid and 250 parts of ethylene glycol was charged into a reaction vessel equipped with a stirrer and a rectifying tube and having an esterified product (97% esterification rate) obtained by direct esterification from terephthalic acid and ethylene glycol.

The reaction contents are heated up to 240 ° C. over 90 minutes while heating at a pressure of 3 kg / cm 2, and maintained at this temperature for 60 minutes while simultaneously performing esterification while removing the reaction product water.

Thereafter, the pressure in the reactor was gradually reduced to normal pressure over 60 minutes while maintaining the temperature at 240 ° C., followed by 5.36 parts of trimethyl phosphate dissolved in ethylene glycol at 10% by weight and the polymerization catalyst in A of Examples 1 to 4 5 wt% dissolved in ethylene glycol and added at the same time, stirred for 10 minutes, the reaction temperature was finally raised to 285 ℃ and gradually depressurized over 60 minutes, finally the pressure in the reaction tube to a high vacuum of 0.8 ~ 0.9 Torr Keep it.

In this way, the polycondensation reaction was continued under high vacuum, and when the reactants reached a certain viscosity, the reaction was terminated and extruded into cooling water through a nozzle at the bottom of the reactor to form a spaghetti, which was then cut at regular intervals to obtain a polymer in a chip state.

Table 1 shows the catalyst content, polymerization time and physical properties of the obtained polyester.

Example 7

A polyester was prepared in the same manner as described in Example 6, but the polymerization catalyst obtained by the method of A of Example 5 was added in the form of a slurry dispersed in ethyl lekglycol at 5% by weight.

The polycondensation reaction time and the physical properties of the obtained polyester are shown in Table 1.

Comparative Example 7

Polyester was prepared in the same manner as described in Example 6, but was added in the form of a slurry in which antimony trioxide was dispersed in ethylene glycol at 5% by weight.

The content of the catalyst and the polycondensation reaction time and the physical properties of the obtained polyester are shown in Table 1.

Claims (7)

In the preparation of linear high molecular weight polyesters by polycondensation of glycol esters of aromatic dicarboxylic acids and / or low molecular weight condensates thereof in the presence of a polycondensation catalyst in the presence of a polycondensation catalyst, an antimony compound and the following structural formula A method for producing a polyester, characterized in that a precondensed antimony compound obtained from the reaction with an esterified pyromellitate salt represented by (II) is used as a polycondensation catalyst. Wherein M ₂ ⁺ is an alkali metal cation or an organic amine salt cation, M ⁺⁺ is an alkaline earth metal cation, and R is an alkyl group having 1 to 18 carbon atoms represented by the following structural formula (III). The method of claim 1, wherein the antimony compound is characterized in that the antimony halide, antimony carboxylate, or antimony alkoxide salt. 2. The esterified pyromellitic acid salt of claim 1 is obtained by obtaining pyromellitic acid derivative esterified from pyromellitic anhydride and an alcohol having 1 to 18 carbon atoms and subsequently organoamine base or metal of alkali or alkaline earth metal. Process for producing a polyester, characterized in that obtained by treating the hydroxide base. The method for producing a polyester according to claim 1, wherein the antimony compound is reacted with a molar ratio of 0.25-1 mole to 1 mole of pyromellitic anhydride. The method for producing a polyester according to claim 1, wherein the content of antimony metal is 80 to 1,000 ppm with respect to the polyester finally obtained in using the preliminary antimony compound as a catalyst. 3. The method of claim 2, wherein the antimony halide is antimony trichloride or antimony tribromide. The method of claim 3, wherein the alcohol is methanol or ethanol.