KR950006132B1 - Method for producing polyester - Google Patents

Abstract

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Description

Production method of polyester

The present invention is to produce a polyester by adding a third compound to the composite catalyst according to the reaction conditions and the composite catalyst consisting of an antimony compound and a titanium compound when preparing the polyester polymer.

Currently produced industrially polyester, especially polyethylene terephthalate has a high crystallinity and a high softening point and excellent properties in many aspects such as strength, chemical resistance, heat resistance, weather resistance and electrical insulation, fiber, film and other It is widely used for industrial materials.

As an industrial method for producing such polyethylene terephthalate, terephthalic acid and ethylene glycol are usually esterified by heating to a reaction temperature of 200 to 280 ° C. under normal pressure or pressure, or dimethyl terephthalate and ethylene glycol in the presence of a catalyst. The polymer obtained by the transesterification method of heating to ˜240 ° C., i.e., bis (beta-hydroxyethyl) terephthalate and / or its oligomer (hereinafter referred to as ester), is subsequently reacted in the presence of a polymerization catalyst at a reaction temperature of 260 to 300 It is prepared by a method of forming a high polymer by a polycondensation reaction at a high vacuum. However, since the direct esterification method is economically more advantageous than the latter transesterification method, the recent esterification method has been adopted in the industrial production of polyester.

When preparing polyesters, reaction catalysts are generally used to facilitate the reaction. Examples of such catalysts include various metal compounds such as antimony, titanium, germanium, tin, zinc, manganese, and lead. It is well known that not only is the difference but also greatly depends on the color and thermal stability of the resulting polyester. That is, since these reactions are carried out for a long time at a high temperature in the presence of a catalyst containing a metal, the resulting polymer is colored yellow or the diethylene glycol content and the end are accompanied by various undesired side reactions to obtain a high degree of polymerization of polyester in a short time. As the carboxyl group concentration is increased above the proper level, physical properties such as melting point and strength decrease of polyester are lowered. Therefore, a method of preparing polyester having good color and excellent physical properties at a fast reaction speed is very important. The most commonly used polycondensation catalysts at present are antimony compounds, especially antimony trioxide, because of their reasonable price, high catalytic activity and excellent thermal stability. However, this antimony trioxide is also difficult to dissolve in ethylene glycol and the reaction solution and tends to precipitate during the reaction, so that the final polyester has gray or yellow green color or poor transparency. This phenomenon becomes even more pronounced by increasing the catalyst usage or increasing the reaction temperature to increase productivity.

Conventionally, various methods have been proposed to shorten the esterification and polycondensation reaction time or to prepare polyesters having excellent color and physical properties as catalysts, but it is difficult to find satisfactory. For example, as a method for shortening the reaction time, a method of reacting a silicon compound with a titanium compound (US Pat. No. 3,927,052), a method of dissolving antimony trioxide, a cobalt compound, and a phosphorus compound in ethylene glycol (JP-A-JP) 53-51,295), a method of using an antimony compound and an organic acid together (Japanese Patent Laid-Open No. 60-166, 320), and the like are known, but in this case, the esterification time and the polycondensation reaction time are not shortened together. The color of the polymer to be colored pale yellow or diethylene glycol or terminal carboxyl group content is increased, causing a lot of problems in the physical properties of the polyester. In addition, as a method of improving the color and physical properties of the polymer, a method of using a cobalt compound and an alkali metal compound together in an antimony compound (Japanese Patent Laid-Open No. 58-117,216), a method of using an antimony compound and a tin compound together (Japanese Patent Publication) Publications 49-31,317) and antimony, tin, cobalt, alkali and phosphorus compounds are known together (Japanese Patent Laid-Open No. 62-265,324), but these methods do not simultaneously improve the color, transparency and physical properties of the polymer. There is no great advantage in terms of shortening reaction time. As described above, in order to manufacture high-quality polyester having high productivity, it is important to shorten the esterification reaction and polycondensation reaction time together with excellent color and other physical properties of the polymer.

Thus, the present inventors have intensively shortened the esterification reaction and the polycondensation reaction time, and the present invention has been continuously studied to prepare high-quality polyester having excellent color and low diethylene glycol content and low terminal carboxyl group concentration.

That is, the present invention is a bis (beta-hydroxyethyl) terephthalate and / or its low by esterifying a terephthalic acid or dicarboxylic acid and its derivatives as a main component and ethylene glycol or glycol and its derivatives as a main component When a polymer is obtained by obtaining an esterified product having a main component and subsequently condensing it to produce a polyester, the weight ratio of the titanium compound to the antimony compound is 0.01 to 100 as a reaction catalyst, which is ethylene glycol or a solvent based on ethylene glycol. It is characterized by using a composite catalyst obtained by dissolving in. The weight ratio of the titanium compound to the antimony compound in the above gives a better result. If the weight ratio of the catalyst is lower or higher than the suggested range, the reaction rate may be significantly slowed or the resulting polyester may be colored yellowish green. As a catalyst, antimony compounds and titanium compounds have an excellent effect especially when using a catalyst solution heated at 20 to 200 ° C., and a better heating temperature is usually 30 to 150 ° C. when using a complex catalyst solution obtained by dissolving them in glycol. . Conventionally, antimony compounds, especially antimony trioxide, are dissolved in ethylene glycol and left for a long time at room temperature to precipitate, resulting in a lack of stability. However, the catalyst system prepared by the above method has a high stability which does not occur. There is this. For example, it is characterized by a very stable that does not occur even if stored for a long time at a temperature of minus 10 ℃.

When the antimony compound is used as the complex catalyst, the antimony compound, for example, antimony trioxide, antimony tetraoxide and antimony pentoxide, and antimony halide such as antimony trichloride and antimony trifluoride, and antimontriacetate, antimontristearate Antimony carboxylates such as antimony tribenzoate, antimontri2-ethylhexenoate, antimontrioctoate and antimontrimethoxide, antimonyethyleneglycoside, antimontriisopropoxide, antimontri n-butoxide And antimony compounds with ethers such as antimony triphenoxide, and antimony hydroxides and sulfides. Among them, antimony trioxide, antimontrea acetate, and antimony ethylene glycoloxide are particularly preferred. In addition, the composite catalyst may be represented by a titanium compound, for example, a titanium halide such as titanium tetrachloride and a titanium compound having an ether bond represented by formula (I) (hereinafter referred to as an ether bond titanium compound).

Ti (OR) ₄

(I)

In general formula (I), R represents an aliphatic or alicyclic alkyl group and an aromatic aryl group. Of course, the four R may be the same or different from each other. For example R is methyl, ethyl, npropyl, isopropyl, ethylene glycol, n-butyl, isobutyl, sec-butyl, tert-butyl, n-amyl, acetylisopropyl, neohexyl, isohexyl, n-hexyl , Heptyl, octyl, decyl, dodecyl, octadecyl, cyclopentyl, cyclohexyl, phenyl and benzyl, and particularly preferably alkyl groups having 8 or less carbon atoms. Another titanium compound is a titanium compound of the general formula (II) in which a compound of the general formula (I) and a phosphite compound [HP (O) (OR ') ₂ ] are coordinated by 1: 2.

(RO) ₄ Ti [HP (O) (OR ′) ₂ ] ₂

(II)

In general formula (II), R is the same as R of general formula (I), and R 'represents an aliphatic and alicyclic alkyl group or an aromatic aryl group, and may be same or different from R mentioned above. For example tetraisopropyl di (dimethyl) phosphito titanate, tetra n-butyl di (diisopropyl) phosphito titanate, tetraisopropyl di (dioctyl) phosphito titanate, tetra octyl di (distearyl Phosphite titanate, tetraoctyl di (ditridecyl) phosphito titanate, tetra (2,2-diallyloxymethyl) butyl di (ditridecyl) phosphito titanate, and the like. In addition, the following titanium compounds may be used. Ie monoalkoxy titanate compounds such as isopropyl triisostearoyl titanate, isopropyl tri (N-ethylenediamino) ethyl titanate, dicumylphenyloxoethylene titanate, di (dioctyl) phosphatoethylene titanate Chelate titanate compounds such as nates, neoalkoxy titanate compounds such as neopentyl (diallyl) oxytri (N-ethylenediamino) ethyl titanate and neopentyl (diallyl) oxytridodecylbenzenesulfonyl titanate, And cycloheteroatomitanate compounds such as cyclo (dioctyl) pyrophosphodidioctyl titanate and dicyclo (dioctyl) pyrophosphate titanate are possible. On the other hand, various antimony compounds and titanium compounds described above may be used together with one kind or two kinds or more, respectively.

The amount of the catalyst used in the present invention does not need to be particularly limited, but may have a sufficient reaction rate depending on the reaction conditions. In other words, the total amount of the antimony compound and the titanium compound is usually 100 to 1000 ppm and the amount is 250 to 750 PM for the finally obtained polyester polymer. The addition time may be added during the esterification reaction or after the esterification reaction, i.e., before the polycondensation reaction, but it is most advantageous to add it before the esterification reaction for the purpose of shortening the overall reaction time to improve productivity. In other words, when a direct esterification reaction is performed using terephthalic acid and ethylene glycol, it may be used in a slurry of terephthalic acid and ethylene glycol. As another method, it may be added separately before the esterification reaction and before the start of the polycondensation reaction.

In the present invention, the direct esterification reaction is advantageous in the well-known reaction temperature range of 200 to 280 ° C., particularly at 220 to 260 ° C., and may be either atmospheric pressure or pressurization. In the case of the transesterification reaction, the catalyst of the present invention may be used instead of the existing catalyst at a reaction temperature of 160 to 240 ° C. Thus, the esterified product obtained by the esterification reaction has a good polycondensation reaction temperature of 260 to 300 ° C., especially a final temperature of 275 to 290 ° C., and increases the vacuum degree while gradually increasing the reaction temperature during polycondensation. A final vacuum of less than 1 torr gives good results. In addition, other reaction catalysts may be used together without departing from the object of the present invention, for example, germanium compounds such as germanium oxide, dibutyltin oxide, tin compounds such as n-butylhydroxytin oxide, zinc acetate, Carboxylate compounds of zinc, manganese, lead such as manganese acetate, red acetate, alkali metal compounds such as sodium or potassium hydroxide and potassium acetate, and alkaline earth metal compounds such as magnesium or calcium hydroxide and potassium acetate Can be.

The present invention is effectively applied when a polyester is prepared by reacting terephthalic acid or dicarboxylic acid and derivatives thereof having the main component with ethylene glycol or glycol having the main component thereof. Representative acids and derivatives thereof in this case are terephthalic acid and dimethyl terephthalate and glycol is ethylene glycol. In addition, the present invention is applied to the production of copolyesters containing at least one third component. However, the content of the third component should not exceed 40 mole percent. In the present invention, the third component is a terephthalic acid component and its derivatives, such as phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenylsulfondicarboxylic acid, diphenyl methanedicarboxylic acid, diphenyl ether dica Aromatic, aliphatic and alicyclic compounds such as carboxylic acid, diphenoxyethanedicarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelinic acid, sebacic acid, cyclohexanedicarboxylic acid, decarinic dicarboxylic acid and the like Group dicarboxylic acids and also ester derivatives such as methyl esters, ethyl esters and phenyl ester compounds of these acids. As glycol components, for example, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4- Aliphatic, alicyclic, and aromatic diols, such as cyclohexane dimethanol, 1, 4- cyclohexanediol, bisphenol A, bisphenol S, bishydroxyethoxy bisphenol A, tetrabromobisphenol A, etc. are mentioned. On the other hand, polyfunctional crosslinking compounds such as trimellitic acid, trimesic acid, pyromellitic acid, trimetholpropane, glycerin, pentaerythritol, and monomethoxy polyethylene glycol, stearyl alcohol, palmitic acid, benzoic acid, naphthoic acid, The same monofunctional end group terminator may be added.

Phosphorus compounds commonly used as thermal stabilizers in the production of polyesters, for example, 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 the like and as an antioxidant, Germany Ciba- Iganox series of hintered phenols, such as Iganox 1010, Iganox 1076, Iganox 1098, etc., may be used. The following additives may be used if necessary. For example, complementary agents such as cobalt acetate, ultraviolet absorbers such as benzotriazole, softening depressants such as triethylamine, quenchers such as titanium oxide, nucleating agents such as silica and alumina, and other compounds as dyes, fluorescent whitening agents, antistatic agents And flame retardants and the like.

As described above, the present invention is very excellent in color and low diethylene glycol content and low terminal carboxyl group concentration as the esterification reaction and polycondensation reaction time is greatly shortened when the polyester is prepared in comparison with the conventional method. A process for producing high quality polyesters using the catalyst of the present invention is presented.

Hereinafter, the present invention will be described in more detail with reference to the examples, but the present invention is not limited to the examples in which the gist is limited. In the examples, "parts" means parts by weight. In addition, the intrinsic viscosity [ eta ] of the polymer was measured at 30 ° C using a mixed solution of phenol (6 parts) and tetrachloroethane (4 parts). Diethylene glycol (DEG) content was measured by gas chromatography by dividing the polymer in hydrazine, and the color of the polymer was measured in a chip state using a color difference meter. As a measure of the degree of coloring, the larger the L value and the smaller the b value, the better the color.

Example 1

Slurry made of ethylene glycol and terephthalic acid by heating a composite catalyst solution in which 250 parts of antimony trioxide and 250 parts of tetraisopropyl di (dioctyl) phosphito titanate dissolved in ethylene glycol was heated at 60 ° C. for 1 hour. Was added as a reaction catalyst. At this time, the molar ratio of ethylene glycol and terephthalic acid used was finally 1.1. The ethylene glycol / terephthalic acid slurry to which the reaction catalyst was added was fed to an esterification apparatus in which esterified product already existed. The esterification reaction was carried out at a reaction temperature of 240 ° C. and atmospheric pressure, and the esterification reaction was terminated at a residence time of 3 hours and 30 minutes. The esterified product was transferred to a polycondensation reactor with a stirrer and a torque meter, and finally to the polyester obtained. 100 piM of trimethylphosphate was added. The temperature was gradually raised to a final temperature of 285 ° C. and the pressure was gradually lowered to a final pressure of 0.8 Torr to polycondensate the reactants. The reaction was terminated in a polycondensation reaction time of 1 hour 53 minutes and extruded into cooling water through a reactor lower nozzle to obtain a polymer in a needle state. The detailed results for this are shown in Table 1.

Comparative Example 1

In Example 1, a direct esterification reaction was performed under the same conditions without adding a reaction catalyst to the ethylene glycol / terephthalic acid slurry. The reaction was terminated at 4 hours and 45 minutes of reaction time, and polycondensation was carried out for 2 hours and 50 minutes by adding 380 pi of antimony trioxide and 100 pi of trimethyl phosphate to the polyester finally obtained under the same polycondensation conditions as in Example 1. A polymer was obtained.

Comparative Example 2

In Example 1, 380 ppm of tetraisopropyl di (dioctyl) phosphitonitanate was added to the ethylene glycol / terephthalic acid slurry as a reaction catalyst, and the esterification reaction was carried out under the same conditions. The esterification reaction was terminated at a reaction time of 3 hours and 35 minutes, and it was polycondensed under the same polymerization conditions as in Example 1. The reaction was terminated at 2 hours and 20 minutes polycondensation reaction time. The reaction results are shown in Table 1.

Example 2

In Example 1, a mixed catalyst solution of 300 PM of antimontria acetate and 200 FI of isopropyl tri (N-ethylenediamino) ethyl titanate was added to the ethylene glycol / terephthalic acid slurry by heating at 120 ° C. for 30 minutes. The esterification reaction was carried out under the same conditions, and the esterification reaction was terminated at a reaction time of 3 hours and 40 minutes. The reaction product was transferred to a polycondensation reactor, and polycondensation was carried out under the same conditions as in Example 1. The reaction was terminated at 1 hour 50 minutes of polycondensation reaction time and the polymer was analyzed. The results are shown in Table 1.

Example 3

In Example 1, 350 ml of antimony trioxide, 150 ml of titanium tetraisopropoxide, and 100 ml of dimethyl phosphite were added to a slurry of ethylene glycol / terephthalic acid by heating at 50 ° C. for 2 hours. Under the same conditions, the esterification reaction terminated the esterification reaction at 3 hours and 23 minutes, and the reaction product was transferred to a condensation condenser to obtain a polymer that required 1 hour and 58 minutes by polycondensation under the same conditions as in Example 1.

Example 4

In the same conditions as in Example 1 and the esterification reaction and the polycondensation reaction, only the catalyst concentration was tested to 300PM each. The esterification reaction was terminated at 3 hours and 18 minutes of esterification time, and the reaction product was transferred to a polycondensation reactor to obtain a polymer at 1 hour and 50 minutes of polycondensation reaction time.

Example 5

In the same conditions as in Example 1, the esterification reaction and the polycondensation reaction were carried out with only catalyst concentrations of 150 and 350 ppm, respectively. The esterification reaction was terminated at 3 hours and 43 minutes of esterification time, and the reaction product was transferred to a polycondensation reactor to obtain a polymer at 1 hour and 48 minutes of polycondensation reaction time.

Example 6

980 parts of dimethyl terephthalate, 640 parts of ethylene glycol and the reaction catalyst used in Example 1 were added to the transesterification reactor at the same concentration, and transesterified at a final temperature of 220 ° C. for 2 hours and 15 minutes. To polycondensation under the same polycondensation conditions as in Example 1 for 1 hour and 42 minutes to obtain a polymer.

Comparative Example 3

Under the same conditions as in Example 6, only 0.31 parts of manganese acetate was added to carry out the transesterification reaction. The esterification reaction was terminated at a reaction time of 3 hours and 30 minutes, and polycondensation was carried out for 2 hours and 35 minutes by adding 380 pi of antimony trioxide and 100 pi of triphenylphosphate to the polyester finally obtained under the same polycondensation conditions as in Example 1. To obtain a polymer.

TABLE 1

Claims (6)

Terephthalic acid or its dicarboxylic acid and its derivatives and its ethylene glycol or its glycol and its derivatives are esterified to produce bis (beta-hydroxyethyl) terephthalate and / or its oligomers as their main component. In the method of preparing a polyester using a complex catalyst composed of an antimony compound and a titanium compound as a catalyst in obtaining a ester by obtaining a esterified product and continuing polycondensation reaction, the composite catalyst comprises ethylene glycol or ethylene glycol as a main component. A method for producing a polyester, wherein the antimony compound and the titanium compound are prepared by dissolving the antimony compound and the titanium compound in a solvent. The titanium compound is a compound represented by the following formula. (RO) ₄ Ti [HP (O) (OR ′) ₂ ] ₂ Wherein R is the same or different and represents an aliphatic or cycloaliphatic alkyl group and an aromatic aryl group, and R 'represents an aliphatic or cycloaliphatic alkyl group and an aromatic aryl group, which may be the same as or different from R. The method for producing a polyester according to claim 1, wherein the antimony compound is selected from the group consisting of antimony trioxide and antimontrea acetate. The method of claim 1, wherein the titanium compound is tetraisopropyl di (dioctyl) phosphito titanate. The method of producing a polyester according to claim 1, wherein the amount of the composite catalyst used is 100-1,000 ppm with respect to the polyester finally obtained. The method of claim 1, wherein the weight ratio of the antimony compound to the titanium compound is 0.01-100. The method for producing a polyester according to claim 1, wherein the glycol solution in which the complex catalyst is dissolved is added to the reaction by heating to 20-200 ° C during the reaction.