JPH04234428A - Manufacture of polyester - Google Patents

Abstract

PURPOSE: To produce a high-quality polyester excellent in hue and physical properties in a short reaction time by reacting terephthalic acid with ethylene glycol in the presence of a composite catalyst comprising an Sb compd. and a Ti compd.

CONSTITUTION: In the process for producing a polyester by reacting terephthalic acid or a dicarboxylic acid component mainly comprising terephthalic acid or a deriv. thereof with ethylene glycol or a glycol component mainly comprising ethylene glycol and polycondensing the resultant bis(β-hydroxyethyl) terephthalate and/or its low polymer, both the reactions are conducted in the presence of a composite catalyst comprising an Sb compd. (e.g. Sb₂O₃ or antimony triacetate) and a Ti compd. [e.g. tetraisopropylbis(dioctyl phosphite) titanate]. Thus, a high-quality polyester excellent in hue and physical properties is produced in a short reaction time.

COPYRIGHT: (C)1992,JPO

Description

Detailed Description of the Invention [0001] [Industrial Application Field] Polyester, especially polyethylene terephthalate, has high crystallinity and a high softening point.
Because it has excellent properties such as strength, chemical resistance, heat resistance, weather resistance, and electrical insulation, it is widely used as fibers, films, and other industrial materials. The present invention relates to a method for producing high-grade polyester without coloring. [0003] As an industrial method for producing polyethylene terephthalate, terephthalic acid and ethylene glycol are heated under normal pressure or pressure to form an esterified product directly from dicarboxylic acid, or dimethyl terephthalate and ethylene A method is known in which a glycol is heated and transesterified in the presence of a catalyst to obtain an esterified product of a low polymer, and then a polycondensation reaction is performed in the presence of a polymerization catalyst to obtain a polyester. Recent industrial manufacturing methods include
Many methods have been implemented to directly obtain esterified products, which are very economically advantageous. [0004] When producing polyester, a catalyst is generally used to facilitate the reaction. Various metal compounds are known as catalysts, and not only the reaction rate differs depending on the type of catalyst, but also the color and thermal stability of the polyester produced differ. These reactions are carried out at high temperatures for long periods of time in the presence of metal-containing catalysts, resulting in various side reactions that may cause the resulting polymer to turn yellow, or reduce the diethylene glycol content and terminal carboxyl groups in the polymer. If the concentration is increased beyond the appropriate level, physical properties such as melting point and strength reduction of the polyester may be degraded. [0005] Currently, the polycondensation catalyst most often used industrially is an antimony compound, especially antimony trioxide, which is reasonably priced, has relatively high catalytic activity, and is excellent in thermal stability. However, antimony trioxide also has low solubility in reaction solutions such as ethylene glycol and tends to precipitate during the reaction, resulting in the resulting polyester being colored gray or yellow-green or having reduced transparency. be. Such a phenomenon becomes more noticeable if the amount of catalyst used is increased or the reaction temperature is raised in order to increase productivity. Conventionally, various methods have been proposed to improve these problems, but none of them are satisfactory. For example, as a method for shortening the reaction time, US Pat. No. 3,927,052 describes a method using a silicon compound and a titanium compound.
3-51,295 discloses a method in which antimony trioxide, a cobalt compound, and a phosphorus compound are dissolved in ethylene glycol, and JP-A-60-166,320 discloses a method in which an antimony compound and an organic acid are used. It describes how to use them together. However, even with this method, both the esterification reaction time and the polycondensation reaction time cannot be shortened, and the resulting polymer may be colored or the diethylene glycol content or the content of terminal carboxyl groups in the polymer may be reduced. Issues such as an increase in demand have not been resolved. As a method for improving the hue and physical properties of polymers, JP-A-58-117,216 discloses a method of using an antimony compound together with a cobalt compound and an alkali metal compound. No. 31,317 discloses a method in which an antimony compound and a tin compound are used together, and JP-A-62-265,324 discloses a method in which antimony, tin, cobalt, an alkali metal compound, and a phosphorus compound are used together. Methods are described. However, even with these methods, it is not possible to simultaneously improve the hue, transparency and physical properties of the polymer. or,
No significant improvement was seen in the reduction of reaction time either. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing high-grade polyester with excellent hue and physical properties, and a method that requires a short reaction time from the viewpoint of productivity. [0012] Means for Solving the Problems [0012] The present invention is directed to the production of terephthalic acid or a dicarboxylic acid containing terephthalic acid as a main component, or a derivative thereof, and ethylene glycol or a dicarboxylic acid containing terephthalic acid as a main component, by a direct esterification method or a transesterification method. reacting glycol to obtain bis(β-hydroxyethyl) terephthalate and/or a low polymer ester thereof,
Further, in a method for producing polyester by subjecting the polycondensation reaction to polycondensation reaction, the method is characterized in that the reaction is carried out in the presence of a composite catalyst consisting of an antimony compound and a titanium compound. Examples of the antimony compound of the present invention include antimony oxides such as antimony trioxide, antimony tetraoxide and antimony pentoxide, antimony halides such as antimony trichloride and antimony trifluoride, antimony triacetate, and antimony triacetate. stearate, antimony tribenzoate, antimony tribenzoate
- Antimony carboxylates such as ethylhexenoate and antimony trioctoate, antimony trimethoxide, 1,2-di(1,2-ethanedioxyantimonooxy)ethyl, antimony triisopropoxide, antimony trimethoxide, Antimony compounds to which ethers are bonded, such as n-butoxide and antimony triphenoxide, as well as antimony hydroxides and sulfides, are included. Among these, preferred antimony compounds are antimony trioxide, antimony triacetate, and antimony triacetate.
,2-di(1,2-ethanedioxyantimonooxy)
It is ethylene. Examples of the titanium compound of the present invention include titanium halides such as titanium tetrachloride, titanium compounds having an ether bond represented by formula (I), and Ti(OR1)4 (I) 00
16] (wherein R1 is the same or different and represents an aliphatic group, a cycloalkyl group, an aryl group, or an aralkyl group). The aliphatic alkyl group represented by R1 is:
Methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-amyl, neohexyl, isohexyl, n-hexyl, heptyl, octyl, decyl, dodecyl, octadecyl, etc. Examples of the cycloalkyl group represented by R1 include cyclopentyl and cyclohexyl. Furthermore, examples of the aryl group and aralkyl group include phenyl and benzyl. Among these, a preferable group represented by R1 is an alkyl group having 8 or less carbon atoms. Different titanium compounds of the present invention include the compound represented by formula (I) and the phosphite compound [HP(
O)(OR2)2] is coordinated in a 1:2 ratio (
Titanium compounds represented by II) can be mentioned. (R1 O)4 Ti[HP(O)(OR2)2]2
(II) [0020] (In the formula, R1 is the same as above, and R2 is the same or different and represents an aliphatic group, a cycloalkyl group, or an aryl group.) [0021] Titanium of the formula (II) of the present invention Specific examples of compounds include tetraisopropyl bis(dimethylphosphite) titanate, tetra n-butyl
Bis(diisopropylphosphite) titanate, tetraisopropyl bis(dioctyl phosphite) titanate, tetraoctyl bis(distearylphosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate and tetra(2,2
-di(allyloxymethyl)butyl) bis(ditridecylphosphite) titanate. Examples of other titanium compounds include alkoxy titanate compounds such as isopropyl triisooctadecyl titanate and isopropyl tris(2-N(2-aminoethyl)aminoethyl)titanate; bis(cumylphenyl)oxoethylene titanate. , chelate titanate compounds such as bis(dioctyloxyphosphonoyl) ethylene titanate; 2
,2-di(allyloxymethyl)butyl tris(2
Neoalkoxytitanate compounds such as -N-(2-aminoethyl)aminoethyl)titanate, 2,2-di(allyloxymethyl)butyl tris(4-dodecylbenzenesulfonyl)titanate. Titanate compounds such as dioctyloxytitanium (dioctyl) diphosphate and titanium bis(dioctyl) diphosphate. Among these titanium compounds, tetraisopropyl bis(dioctylphosphite) titanate, isopropyl tris(2-N(2-aminoethyl)aminoethyl)titanate, and tetraisopropyl titanate are preferably used. [0024] The above-mentioned antimony compounds and titanium compounds can be used alone or in combination. The composite catalyst used in the present invention has a weight ratio of titanium compound to antimony compound of 0.
01 to 100, preferably 0.1 to 9.0. The amount of the decomposition catalyst used is not particularly limited, but preferably the total amount of the antimony compound and titanium compound is 100 to 1,000 ppm based on the polyester to be produced.
and particularly preferably 250 to 750 ppm. The composite catalyst of the present invention is prepared by heating a composite catalyst solution obtained by dissolving an antimony compound and a titanium compound in ethylene glycol or a solvent mainly composed of ethylene glycol at 20° to 200°C, preferably 30 to 150°C. It can be used by heating and adding it to the reaction system. Antimony compounds, especially antimony trioxide, have low stability and may form a precipitate if left at room temperature for a long time after being dissolved in ethylene glycol. However, the catalyst system produced by the above method This catalyst system does not generate such precipitates and is extremely stable. For example, no precipitate was formed even when stored for a long time at a temperature of -10°C. Additionally, other catalysts may be used without departing from the objectives of the invention. For example, germanium compounds such as germanium oxide, tin compounds such as dibutyltin oxide, n-butylhydroxytin oxide, zinc acetate, manganese acetate,
Carboxylate salts of zinc, manganese and lead such as lead acetate, alkali metal compounds such as sodium or potassium hydroxide and potassium acetate, alkaline earth metal compounds such as magnesium or calcium hydroxide and calcium acetate. can be given. In the present invention, the catalyst may be added before the start of the esterification reaction, during the reaction, or after the end of the reaction, that is, before the polycondensation reaction. However, for the purpose of shortening the total reaction time to improve productivity, it is advantageous to add it before the start of the esterification reaction. When obtaining an esterified product directly from terephthalic acid and ethylene glycol, it is advantageous to add a catalyst to a slurry of terephthalic acid and ethylene glycol for reaction. Furthermore, the reaction proceeds advantageously even if it is added in portions before the start of the esterification reaction and before the start of the polycondensation reaction. [0031] The direct esterification reaction is carried out at a reaction temperature of 200 to 280°C, preferably 220 to 280°C under normal pressure or increased pressure.
Advantageously, it is carried out at 60°C. In the case of transesterification, the catalyst of the present invention is used in place of the conventional catalyst at a reaction temperature of 160 to 240°C. The esterified product thus obtained can be subjected to a polycondensation reaction at a reaction temperature of 260 to 300° C. under normal pressure or increased pressure. The reaction temperature was gradually increased and the degree of vacuum was also gradually increased, and at the final stage of the reaction, the reaction temperature was 27.
It is advantageous to carry out the reaction at a temperature of 5 to 290° C. and a degree of vacuum of 1 Torr or less. Typical acids and derivatives thereof that can be used in the present invention are terephthalic acid and dimethyl terephthalate, and a typical glycol is ethylene glycol. In addition, at least one kind of third component can be added and reacted. However, it is preferred that the third component does not exceed 40 mole percent. Examples of the third component of the present invention include phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenylmethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, malonic acid, succinic acid, and glutaric acid. Aromatic acids, such as adipic acid, azelaic acid, sebacic acid, cyclohexanedicarboxylic acid, decanedicarboxylic acid,
Aroaliphatic, aliphatic and cycloaliphatic dicarboxylic acids and ester derivatives of these acids, such as methyl esters, ethyl esters and phenyl esters, and 1,3-propanediol, 1,2-propanediol, 1,4- Butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, bisphenol A, bisphenol S, bishydroxyethoxybisphenol A , tetrabromobisphenol A, and other aliphatic, cycloaliphatic, and aromatic diols. The present invention also provides polyfunctional crosslinking agent compounds such as trimellitic acid, trimesic acid, pyromellitic acid, trimethylolpropane, glycerin, and pentaerythritol, and monomethoxypolyethylene glycol, stearyl alcohol, palmitic acid, and benzoic acid. The reaction can also be carried out by adding a monofunctional end group terminator such as naphthoic acid or the like. Furthermore, the present invention provides thermal stabilizers to be added when producing polyester, such as phosphoric acid, phosphorous acid, metaphosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, trioctyl phosphate, dimethyl phosphite, diethyl Phosphite, dicyclohexyl phosphite, diphenyl phosphite, dioctyl phosphite, dimethyl pyrophosphate, diethyl pyrophosphate, diphenyl pyrophosphate, dicyclohexyl pyrophosphate, dioctyl pyrophosphate, and antioxidants such as Irganox 1010, Irganox 1076, Irga Ciba-Geigy products such as Nox 1098 can also be used if necessary. In addition, color preservatives such as cobalt acetate, ultraviolet absorbers such as benzotriazole, softening point lowering inhibitors such as triethylamine, quenchers such as titanium oxide, nucleating agents such as silica and alumina, Dyes, fluorescent brighteners, antistatic agents, and flame retardants may also be mentioned as those that can be used. [Example] Next, the present invention will be explained in more detail with reference to Examples, but the method of the present invention is not limited to these Examples. In the examples, "parts" means parts by weight. In addition, the intrinsic viscosity [η] of the polymer is phenol (6 parts)
and tetrachloroethane (4 parts) at 30°C. Further, the diethylene glycol (DEG) content was determined by decomposing the polymer with hydrazine hydrate and measuring it by gas chromatography. The hue of the polymer was measured in chip form using a colorimeter. The L value and b value obtained here are scales representing the lightness and degree of coloring of the polymer, respectively, and generally, the larger the L value and the smaller the b value, the better the hue. Example 1 250p of antimony oxide was added to the polyester to be produced.
A composite catalyst solution containing 250 ppm of tetraisopropyl bis(dioctyl phosphite) titanate dissolved in ethylene glycol was heated at 60° C. for 1 hour, and then added as a reaction catalyst to a slurry prepared with ethylene glycol and terephthalic acid. The molar ratio of ethylene glycol and terephthalic acid used at this time was ultimately 1.
I set it to 1. The ethylene glycol/terephthalic acid slurry to which the reaction catalyst had been added in this manner was supplied to the esterification reactor in which the esterified product was already present, and the esterified product was produced at normal pressure, at a reaction temperature of 240°C, and for a reaction time of 3 hours and 30 minutes. Obtained. This esterified product is transferred to a polycondensation reactor equipped with a stirrer and a torque meter, and 100 ppm of trimethyl phosphate is added to the resulting polyester.
was added. Then, the temperature of the polycondensation reactor was gradually increased to a final temperature of 28
5℃, gradually lower the pressure in the reactor to a final pressure of 0.8
The reaction was completed after a reaction time of 1 hour and 53 minutes. After the reaction was completed, the reaction mixture was extruded into cooling water through the lower nozzle of the reactor to obtain a polymer in the form of chips. Table 1 shows the intrinsic viscosity, diethylene glycol (DEG) content, terminal carboxyl group concentration, and hue of the produced polymer. Comparative Example 1 The reaction time was 4 hours and 45 minutes in the same manner as in Example 1 without adding a reaction catalyst to the ethylene glycol/terephthalic acid slurry.
Direct esterification reaction was carried out in minutes. Next, in the same manner as in Example 1, antimony trioxide 3 was added to the polyester to be produced.
80ppm, trimethyl phosphate 100ppm
was added and polycondensed for 2 hours and 50 minutes, and treated in the same manner as in Example 1 to obtain a polymer. Table 1 shows the results of the obtained polymer.
It was shown to. Comparative Example 2 380 ppm of tetraisopropyl bis(dioctyl phosphite) titanate was added as a reaction catalyst to the ethylene glycol/terephthalic acid slurry.
In the same manner as in Example 1, a direct ester reaction was carried out for a reaction time of 3 hours and 35 minutes, and then polycondensation was carried out under the same polymerization conditions as in Example 1. In this case, the polycondensation reaction time was 2 hours and 20 minutes. Table 1 shows the results of the obtained polymer. Example 2 Similarly to Example 1, antimony triacetate 3 was added to the ethylene glycol/terephthalic acid slurry as a reaction catalyst.
00ppm and isopropyl tris(2-N-(aminoethyl)aminoethyl)titanate 200ppm
The composite catalyst solution was heated at 120° C. for 30 minutes and added. The esterification reaction was carried out under the same conditions as in Example 1. The esterification reaction was completed after a reaction time of 3 hours and 40 minutes, and Example 1
Polycondensation was carried out under the same conditions as . Polycondensation reaction time 1 hour 50
The reaction was completed in minutes, and a polymer was obtained in the same manner as in Example 1. The results are shown in Table 1. Example 3 Similarly to Example 1, 350p of antimony trioxide was added to the ethylene glycol/terephthalic acid slurry as a reaction catalyst.
pm and tetraisopropyl titanate 150pp
An ethylene glycol solution containing 100 ppm of dimethyl phosphite was heated at 50° C. for 2 hours and then added. The esterification reaction was carried out under the same conditions as in Example 1, and the esterified product obtained in a reaction time of 3 hours and 23 minutes was used as Example 1.
The polycondensation reaction was carried out under the same conditions as . The polycondensation reaction was completed in 1 hour and 58 minutes, and a polymer was obtained in the same manner as in Example 1. The results are shown in Table 1. Example 4 Similar to Example 1, the esterification reaction and polycondensation reaction were carried out under the same conditions as in Example 1 except that the catalyst concentration was changed to 300 ppm. In this case, the esterification reaction time is 3 hours 1
The polycondensation reaction time was 1 hour and 50 minutes. Table 1 shows the results of the polymer obtained by the same treatment as in Example 1. Example 5 Same as Example 4, the catalyst concentration was 150 ppm and 3
The esterification reaction and polycondensation reaction were carried out at a concentration of 50 ppm. In this case, the esterification reaction time was 3 hours and 43 minutes, and the polycondensation reaction time was 1 hour and 48 minutes. The results are shown in Table 1. Example 6 The same concentration of the composite catalyst solution used in Example 1 was added to a slurry of 970 parts of dimethyl terephthalate and 640 parts of ethylene glycol, and the mixture was heated at a final temperature of 220° C. for 2 hours in the same manner as in Example 1. A transesterification reaction was carried out. This esterified product was reacted under the same polycondensation conditions as in Example 1. Table 1 shows the results of the polymer obtained with a reaction time of 1 hour and 42 minutes. Comparative Example 3 A transesterification reaction was carried out under the same conditions as in Example 6 except that 0.31 part of manganese acetate was used as the reaction catalyst. The esterification reaction product obtained after a reaction time of 3 hours and 30 minutes was reacted under the same polycondensation conditions as in Example 1. A polymer was obtained in a reaction time of 2 hours and 35 minutes. In this case, 380 ppm of antimony trioxide and 100 ppm of triphenyl phosphate were added to the polyester produced as a catalyst. Table 1 shows the results of the obtained polymer. Effects of the Invention The method of the present invention shortens the reaction time required to produce polyester, produces a high-grade polymer with excellent hue, and has a low diethylene glycol content and a low concentration of terminal carboxyl groups. This is a method for producing polyester. [Table 1]

Claims (6)

[Claims] Claim 1: Bis(β-hydroxyethyl) terephthalate and/or bis(β-hydroxyethyl) terephthalate is produced by reacting terephthalic acid, a dicarboxylic acid containing terephthalic acid as a main component, or a derivative thereof with ethylene glycol or a glycol containing terephthalic acid as a main component.
Or a method for producing a polyester by obtaining a low polymer ester thereof and further subjecting it to a polycondensation reaction, the method comprising reacting in the presence of a composite catalyst consisting of an antimony compound and a titanium compound. 2. The method according to claim 1, wherein the antimony compound is antimony trioxide or antimony triacetate. [Claim 3] The titanium compound is tetraisopropyl bis(dioctylphosphite) titanate, isopropyl tris(2-N-(2-aminoethyl)
2. The method according to claim 1, wherein the titanate is aminoethyl titanate or tetraisopropyl titanate. 4. The manufacturing method according to claim 1, wherein the amount of the composite catalyst used is 100 to 1,000 ppm based on the polyester to be produced. 5. The manufacturing method according to claim 1, wherein in the composite catalyst, the weight ratio of the antimony compound to the titanium compound is 0.01 to 100. Claim 6: Claim 1, wherein the glycol solution in which the composite catalyst is dissolved is heated to 20 to 200°C and added to the reaction system.
manufacturing method.