JP2005162925A - Catalyst for polyester polymerization and method for producing polyester by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a catalyst for polymerization providing a polyester scarcely containing a foreign matter and having good color tone and to provide a method for producing the polyester by using the catalyst. <P>SOLUTION: In the catalyst for polyester polymerization, the number of a titanium atom in one molecule of the catalyst is ≥20 and ≤200 and the composition ratio P of the titanium atom to a phosphorus atom satisfies the formula (1): 0.5<P<2.0. The method for producing the polyester comprises using the catalyst. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polyester polymerization catalyst and a method for producing a polyester capable of obtaining a polyester having a good color tone with less foreign matter.

  Polyester is used for various purposes because of its useful functionality, and is used for clothing, materials, and medical use, for example. Among them, polyethylene terephthalate is excellent in terms of versatility and practicality and is preferably used.

  In general, polyethylene terephthalate is produced from terephthalic acid or an ester-forming derivative thereof and ethylene glycol. In a commercial process for producing a high molecular weight polymer, an antimony compound is widely used as a polycondensation catalyst. However, polymers containing antimony compounds have some undesirable properties as described below.

  For example, when a polymer obtained using an antimony catalyst is melt-spun into a fiber, it is known that an antimony catalyst residue is deposited around the die hole. As this deposition progresses, it becomes a cause of defects in the filament, so that it needs to be removed in a timely manner. The deposition of the antimony catalyst residue is considered to be due to the antimony compound in the polymer being transformed in the vicinity of the die and partially vaporizing and dissipating, and then a component mainly composed of antimony remains in the die.

  In addition, the antimony catalyst residue in the polymer tends to be relatively large particles, and it becomes a foreign substance, causing an increase in the filtration pressure of the filter during molding, causing yarn breakage during spinning or film tearing during film formation, etc. It has undesirable characteristics and contributes to a decrease in operability.

  In view of the above background, there is a demand for polyesters that contain little or no antimony. Thus, germanium compounds are known when the role of a polycondensation catalyst is required for compounds other than antimony compounds, but germanium compounds are very expensive and difficult to use for general purposes.

  On the other hand, the proposal which uses the titanium complex which consists of a titanium compound and a phosphorus compound as a polymerization catalyst as a catalyst for polyester polymerization is made | formed (refer patent documents 1-3). According to this method, although foreign substances resulting from the catalyst can be reduced, it is not sufficient, and the color tone of the resulting polymer is not sufficient. Accordingly, there is a need for further improvements in titanium compounds.

Therefore, in the present invention, as a result of improving the above-mentioned problems and intensively studying a polyester with less yarn breakage, the object of the present invention can be achieved by using a compound of titanium and phosphorus having a specific structure as a polymerization catalyst. Obtained knowledge.
JP 2001-524536 A (1st page) Japanese translation of PCT publication No. 2002-512267 (first page) JP 2002-293909 A (first page)

  The object of the present invention is for polyester polymerization, which solves the above-mentioned conventional problems, has good yarn-forming properties and film-forming properties, has fewer foreign matters than conventional products, and can obtain a polyester having excellent polyester color tone. The object is to provide a catalyst and a method for producing a polyester using the catalyst.

  The above-mentioned problem is that the number of titanium atoms in one molecule of the catalyst is 20 or more and 200 or less, and the composition ratio P of the titanium atoms to the phosphorus atoms satisfies the following formula (1), And a polyester production method using the same.

    (1) 0.5 <P <2.0

  According to the polyester polymerization catalyst of the present invention and the polyester production method using the same, it is possible to obtain a polyester having a good color tone with less foreign matter.

  The polyester of the present invention is a polymer synthesized from a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. What can be used as molded articles, such as a fiber, a film, and a bottle, is preferable.

  Specific examples of such polyester include polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polyethylene-1,2- And bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate. The present invention is suitable for polyethylene terephthalate or polyester copolymers mainly containing ethylene terephthalate units, which are most commonly used.

  In addition to diethylene glycol, these polyesters include dicarboxylic acids such as adipic acid, isophthalic acid, sebacic acid, phthalic acid, naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, and cyclohexanedicarboxylic acid, and esters thereof. Formable derivatives, dioxy compounds such as polyethylene glycol, hexamethylene glycol, neopentyl glycol, polypropylene glycol, cyclohexanedimethanol, oxycarboxylic acids such as p- (β-oxyethoxy) benzoic acid and ester-forming derivatives thereof It may be polymerized.

  In the polyester polymerization catalyst of the present invention, the number of titanium atoms in one molecule is 20 to 200, and the composition ratio P of titanium atoms to phosphorus atoms is within the range of the following formula (1). Is important from the point of view.

(1) 0.5 <P <2.0
About the number of the titanium atoms in 1 molecule, 20-100 are preferable, More preferably, it is 20-50. The constituent ratio P of titanium atoms and phosphorus atoms is preferably 0.6 to 1.7, more preferably 0.6 to 1.2.

  In the polyester polymerization catalyst of the present invention, the substituent of the titanium atom is preferably at least one selected from the group consisting of functional groups represented by the following formulas 1 to 6.

(In Formula 1 to Formula 6, R _{1 to} R ₃ each independently have hydrogen, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group, a hydroxyl group, a carbonyl group, an acetyl group, a carboxyl group, an ester group, or an amino group. Represents a hydrocarbon group having 1 to 30 carbon atoms.)
Formula 1 of the present invention comprises an alkoxy group such as ethoxide, propoxide, isopropoxide, butoxide, 2-ethylhexoxide, or the like, or a hydroxy polyvalent carboxylic acid compound such as lactic acid, malic acid, tartaric acid, citric acid, etc. A functional group is mentioned.

  Formula 2 includes a functional group composed of a β-diketone compound such as acetylacetone and a ketoester compound such as methyl acetoacetate and ethyl acetoacetate.

  Moreover, as Formula 3, the functional group which consists of phenoxy, cresylate, salicylic acid, etc. is mentioned.

  Formula 4 includes acylate groups such as lactate and stearate, phthalic acid, trimellitic acid, trimesic acid, hemimellitic acid, pyromellitic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacin Polycarboxylic acid compounds such as acid, maleic acid, fumaric acid, cyclohexanedicarboxylic acid or their anhydrides, ethylenediaminetetraacetic acid, nitrilotripropionic acid, carboxyiminodiacetic acid, carboxymethyliminodipropionic acid, diethylenetriaminopentaacetic acid And functional groups composed of nitrogen-containing polyvalent carboxylic acids such as triethylenetetraminohexaacetic acid, iminodiacetic acid, iminodipropionic acid, hydroxyethyliminodiacetic acid, hydroxyethyliminodipropionic acid, and methoxyethyliminodiacetic acid.

Formula 5 includes functional groups composed of aniline, phenylamine, diphenylamine, and the like.
Among these, the inclusion of Formula 1 and / or Formula 4 is preferable from the viewpoint of the thermal stability and color tone of the polymer.

  The method for synthesizing the catalyst for polyester polymerization of the present invention includes, for example, (1) mixing a titanium compound in a solvent and dissolving a part or all of the titanium compound in the solvent, and dissolving or diluting the phosphorus compound in the solvent. To do. (2) In the case of using a ligand of a titanium compound such as a hydroxycarboxylic acid compound or a polyvalent carboxylic acid compound, the titanium compound or the ligand compound is mixed in a solvent, and a part or all thereof is mixed in the solvent. It is obtained by dissolving, dissolving and diluting the ligand compound or titanium compound in a stock solution or solvent in this mixed solution and dropping, and then further adding a phosphorus compound to this mixed solution. In particular, in this case, when the last 1 to 30 mol% of the phosphorus compound is reacted, 80% or more of the solvent is ethylene glycol, and the titanium atom concentration in the reaction system is 1 wt% or less, the solid in the liquid This is preferable from the viewpoint of suppressing foreign matter formation. The proportion of the phosphorus compound is more preferably 15 to 30 mol%, the proportion of ethylene glycol in the solvent is more preferably 90% or more, and the titanium atom concentration in the reaction system is more preferably 0.7% by weight or less. .

  As a solid content ratio in this liquid, when a dispersion of a catalyst compound having a titanium atom concentration of 1% by weight or less is filtered through a 0.2 μm filter, the ratio of the filtered product weight R to the total catalyst compound weight S It is preferable that Q is 20% or less. Q is preferably 10% or less, more preferably 5% or less.

  The above reaction conditions are preferably performed by heating at a temperature of 0 to 200 ° C. for 1 minute or longer, and further by heating at a temperature of 20 to 100 ° C. for 2 to 100 minutes. The reaction pressure at this time is not particularly limited, and may be normal pressure. The solvent used here can be selected from those capable of dissolving part or all of the titanium compound, the phosphorus compound and the compound bonded to the titanium atom. Specifically, methanol, ethanol, 1-propanol 2-propanol, ethylene glycol, propanediol, butanediol, diethyl ether, acetone, ethyl acetate, dimethyl sulfoxide, dimethylformamide, tetrahydrofuran, dichloromethane, 1,2-dichloroethane and the like.

  In addition, as a raw material titanium compound used in the synthesis | combination of the catalyst for polyester polymerization of this invention, if it has the said substituent or has a substituent easily exchangeable with them, it will not specifically limit. Specific examples include titanium tetraisopropoxide, titanium tetrabutoxide, titanium diisopropoxybisacetylacetonate, titanium triethanolaminate isopropoxide, and the like.

  The starting phosphorus compound is preferably at least one selected from phosphoric acid compounds and at least one selected from phosphonic acid compounds and phosphinic acid compounds. More preferably it is a seed. Specifically, for example, phosphoric acid compounds include phosphoric acid, phosphoric acid sodium salt, phosphoric acid potassium salt, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, and the like. Is phosphorous acid, sodium salt of phosphorous acid, potassium salt of phosphorous acid, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, methylphosphonic acid, ethylphosphonic acid, propylphosphonic acid, isopropylphosphonic acid, Butylphosphonic acid, phenylphosphonic acid, benzylphosphonic acid, tolylphosphonic acid, xylylphosphonic acid, biphenylphosphonic acid, naphthylphosphonic acid, anthrylphosphonic acid, 2-carboxyphenylphosphonic acid, 3-carboxyphenylphosphonic acid, 4- Carboxyphenylphosphonic acid, 2,3-dicarboxy Phenylphosphonic acid, 2,4-dicarboxyphenylphosphonic acid, 2,5-dicarboxyphenylphosphonic acid, 2,6-dicarboxyphenylphosphonic acid, 3,4-dicarboxyphenylphosphonic acid, 3,5-dicarboxyphenyl Phosphonic acid, 2,3,4-tricarboxyphenylphosphonic acid, 2,3,5-tricarboxyphenylphosphonic acid, 2,3,6-tricarboxyphenylphosphonic acid, 2,4,5-tricarboxyphenylphosphonic acid 2,4,6-tricarboxyphenylphosphonic acid, methylphosphonic acid dimethyl ester, methylphosphonic acid diethyl ester, ethylphosphonic acid dimethyl ester, ethylphosphonic acid diethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, phenyl Suphonic acid diphenyl ester, benzylphosphonic acid dimethyl ester, benzylphosphonic acid diethyl ester, benzylphosphonic acid diphenyl ester, lithium (ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate), sodium (3,5- Di-tert-butyl-4-hydroxybenzylphosphonate ethyl), magnesium bis (3,5-di-tert-butyl-4-hydroxybenzylphosphonate ethyl), calcium bis (3,5-di-tert-butyl- 4-hydroxybenzylphosphonic acid ethyl), diethylphosphonoacetic acid, methyl diethylphosphonoacetate, ethyl diethylphosphonoacetate and the like. Examples of phosphinic acid compounds include hypophosphorous acid, sodium hypophosphite, hypophosphorous acid. Potassium acid, methylphosphine Phosphoric acid, ethylphosphinic acid, propylphosphinic acid, isopropylphosphinic acid, butylphosphinic acid, phenylphosphinic acid, tolylphosphinic acid, xylylphosphinic acid, biphenylylphosphinic acid, diphenylphosphinic acid, dimethylphosphinic acid, diethylphosphinic acid, Dipropylphosphinic acid, diisopropylphosphinic acid, dibutylphosphinic acid, ditolylphosphinic acid, dixylphosphinic acid, dibiphenylylphosphinic acid, naphthylphosphinic acid, anthrylphosphinic acid, 2-carboxyphenylphosphinic acid, 3-carboxyphenylphosphine Acid, 4-carboxyphenylphosphinic acid, 2,3-dicarboxyphenylphosphinic acid, 2,4-dicarboxyphenylphosphinic acid, 2,5-dicarboxypheny Phosphinic acid, 2,6-dicarboxyphenylphosphinic acid, 3,4-dicarboxyphenylphosphinic acid, 3,5-dicarboxyphenylphosphinic acid, 2,3,4-tricarboxyphenylphosphinic acid, 2,3,5 -Tricarboxyphenylphosphinic acid, 2,3,6-tricarboxyphenylphosphinic acid, 2,4,5-tricarboxyphenylphosphinic acid, 2,4,6-tricarboxyphenylphosphinic acid, bis (2-carboxyphenyl) Phosphinic acid, bis (3-carboxyphenyl) phosphinic acid, bis (4-carboxyphenyl) phosphinic acid, bis (2,3-dicarboxylphenyl) phosphinic acid, bis (2,4-dicarboxyphenyl) phosphinic acid, Bis (2,5-dicarboxyphenyl) phosphinic acid, bi (2,6-dicarboxyphenyl) phosphinic acid, bis (3,4-dicarboxyphenyl) phosphinic acid, bis (3,5-dicarboxyphenyl) phosphinic acid, bis (2,3,4-tricarboxyphenyl) Phosphinic acid, bis (2,3,5-tricarboxyphenyl) phosphinic acid, bis (2,3,6-tricarboxyphenyl) phosphinic acid, bis (2,4,5-tricarboxyphenyl) phosphinic acid, and bis (2,4,6-tricarboxyphenyl) phosphinic acid, methylphosphinic acid methyl ester, dimethylphosphinic acid methyl ester, methylphosphinic acid ethyl ester, dimethylphosphinic acid ethyl ester, ethylphosphinic acid methyl ester, diethylphosphinic acid methyl ester, Ethyl ethyl phosphinate Esters, diethylphosphinic acid ethyl ester, phenylphosphinic acid methyl ester, phenylphosphinic acid ethyl ester, phenylphosphinic acid phenyl ester, diphenylphosphinic acid methyl ester, diphenylphosphinic acid ethyl ester, diphenylphosphinic acid phenyl ester, benzylphosphinic acid methyl ester, Examples include benzylphosphinic acid ethyl ester, benzylphosphinic acid phenyl ester, bisbenzylphosphinic acid methyl ester, bisbenzylphosphinic acid ethyl ester, and bisbenzylphosphinic acid phenyl ester.

  In particular, from the viewpoint of foreign matter suppression and color tone improvement, phosphoric acid and phosphinic acid are preferable. Among them, phosphoric acid compounds are phosphoric acid and / or phosphate, phosphinic acid compounds are hypophosphorous acid and / or Alternatively, hypophosphite or diphenylphosphinic acid and / or diphenylphosphinate is preferable.

  The catalyst of the present invention is a polyethylene terephthalate obtained by substantially completing the ester reaction or transesterification reaction in a polymer synthesized from a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. It refers to a compound that substantially contributes to the acceleration of all or some of the polycondensation reactions that increase the degree of polymerization of the low polymer by a dediol reaction.

  Therefore, titanium dioxide particles generally used as inorganic particles in fiber matting agents and the like have substantially no catalytic effect on the above reaction and can be used as the catalyst of the present invention. Different from titanium and phosphorus compounds.

  The compound of titanium and phosphorus (excluding titanium dioxide particles) in the present invention is preferably contained in an amount of 0.5 to 150 ppm in terms of titanium atom with respect to the obtained polymer. When it is 1 to 100 ppm, the thermal stability and color tone of the polymer become better, and it is more preferably 3 to 50 ppm.

  The titanium-phosphorus compound used in the present invention may be added to the polyester reaction system as it is, but is mixed in advance with a solvent containing a diol component that forms a polyester such as ethylene glycol or propylene glycol, and the It is preferable to add a low-boiling component such as alcohol used in the compound synthesis to the reaction system after removing it to such an extent that the solid content does not precipitate, because the generation of foreign matter in the polymer is further suppressed. The solid content in the liquid is preferably 20% or less in terms of the foreign matter suppression from the ratio Q of the filtered product weight R to the total catalyst compound weight S when filtered through a 0.2 μm filter. The timing of addition may be substantially before the start of the polycondensation reaction, and may be added before the esterification reaction or transesterification reaction, or after the completion of the reaction and before the start of the polycondensation reaction catalyst. Furthermore, a phosphorus compound may be added separately from the viewpoints of color tone improvement and thermal stability. In this case, in order to suppress the deactivation of the catalyst due to the contact between the catalyst for polyester polymerization of the present invention containing a compound of titanium and phosphorus and the phosphorus compound, a method of adding to different reaction tanks, A method of setting the addition interval between the polyester polymerization catalyst and the phosphorus compound of the invention to 1 to 15 minutes or a method of separating the addition position may be used.

  When the cobalt compound or the manganese compound is added at an arbitrary point in the method for producing the polyester of the present invention, the color tone of the polymer obtained is favorable. The cobalt compound used in this case is not particularly limited, and specific examples include cobalt chloride, cobalt nitrate, cobalt carbonate, cobalt acetylacetonate, cobalt naphthenate, and cobalt acetate tetrahydrate. Further, the manganese compound is not particularly limited, and specifically, for example, manganese chloride, manganese bromide, manganese nitrate, manganese carbonate, manganese acetylacetonate, manganese acetate tetrahydrate, manganese acetate dihydrate, etc. Can be mentioned.

  Further, for the purpose of improving the color tone of the polymer obtained and the thermal stability of the polymer, an alkali metal compound, an alkaline earth metal compound, an aluminum compound, a zinc compound, a tin compound, or the like may be added.

  Furthermore, in addition to particles such as titanium dioxide, silicon oxide, calcium carbonate, silicon nitride, clay, talc, kaolin and carbon black, a coloring inhibitor, a stabilizer, an antioxidant and the like may be added.

  A method for producing the polyester of the present invention will be described. Although the example of a polyethylene terephthalate is described as a specific example, it is not limited to this.

  Polyethylene terephthalate is usually produced by one of the following processes. (1) A process in which terephthalic acid and ethylene glycol are used as raw materials, a low polymer is obtained by direct esterification reaction, and a high molecular weight polymer is obtained by subsequent polycondensation reaction, and (2) dimethyl terephthalate and ethylene glycol are used as raw materials. In this process, a low polymer is obtained by a transesterification reaction, and a high molecular weight polymer is obtained by a subsequent polycondensation reaction. Also, in the transesterification reaction, the process proceeds using a compound such as manganese, calcium, magnesium, zinc, lithium and the like, and the catalyst used in the reaction is deactivated after the transesterification reaction is substantially completed. The phosphorus compound is added.

  The production method of the present invention comprises a matting agent applied to a low polymer obtained in any stage of the series of reactions (1) or (2), preferably in the first half of the series of reactions (1) or (2). After adding additives such as titanium dioxide particles, cobalt compounds and manganese compounds, the polycondensation catalyst is added with the titanium and phosphorus compounds described above to perform a polycondensation reaction to obtain high molecular weight polyethylene terephthalate. is there.

  Further, the above reaction can be applied to a batch, semi-batch, or continuous system.

Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the physical-property value in an Example was measured by the method described below.
(1) Intrinsic viscosity of polymer IV
Measurement was performed at 25 ° C. using orthochlorophenol as a solvent.
(2) Color tone of polymer The obtained polymer is rapidly cooled from a molten state, molded into a chip shape, and filled in a quartz glass container, and then a Hunter color difference meter (SM color computer manufactured by Suga Test Instruments Co., Ltd.) Measurement was performed using model SM-3) to obtain L and b values of the hunter.

As the polymer color tone, the b value is preferably 4 or less, more preferably 3 or less, and particularly preferably 1.5 or less.
(3) Solution haze Integrating sphere type photoelectric photometry method by dissolving 2.0 g of a sample to be measured in 20 mL of orthochlorophenol and using a quartz cell having a light path length of 10 mm and a haze meter (HGM-2DP type, manufactured by Suga Test Instruments Co., Ltd.) The analysis was performed. As the amount of foreign matter in the polymer, the haze value is preferably 2.0 or less, more preferably 1.5 or less.
(4) Content of Titanium Element and Phosphorus Element in Polyester The content was determined with a fluorescent X-ray elemental analyzer (manufactured by Horiba, Ltd., MESA-500W type). When the polyester contains titanium dioxide particles, fluorescent X-ray analysis was performed after the following pretreatment. That is, polyester is dissolved in orthochlorophenol (5 g of polymer per 100 g of solvent), and after adding the same amount of dichloromethane as this polymer solution to adjust the viscosity of the solution, a centrifuge (rotation speed 18000 rpm, 1 hour) To settle the particles. Thereafter, only the supernatant liquid is collected by the gradient method, and the polymer is reprecipitated by adding the same amount of acetone as the supernatant liquid, and then filtered through a 3G3 glass filter (manufactured by IWAKI). After washing with acetone, the acetone was removed by vacuum drying at room temperature for 12 hours. The polymer obtained by performing the above pretreatment was analyzed for titanium element, phosphorus element, antimony element and manganese element.

On the other hand, when the titanium dioxide particles are not contained, it is not necessary to perform a pretreatment, and the polymer may be analyzed as it is.
(5) Weight ratio Q of solid content of 0.2 μm or more in all catalyst compounds
A certain amount of the catalyst dispersion was suction filtered through a 0.2 μm filter, and the filter was dried under reduced pressure. The weight R of the filtered material was determined from the weight change of the filter before and after that. Further, the solid obtained by distilling off the solvent from a certain amount of the dispersion was purified, and the weight S of all catalyst compounds was determined. Using these values, Q was calculated from the following equation (2).

(2) Q = 100R / S
(6) Number of titanium atoms in one molecule of catalyst The catalyst solution was analyzed by LC-MS (QP8000 manufactured by Shimadzu Corporation). Of the signals having a titanium isotope pattern, the number of titanium atoms was determined by dividing the largest molecular weight by the molecular weight of the signal belonging to the smallest structural unit.

Example 1
A. Catalyst Preparation Lactic acid (27.3 g, 0.30 mol) was dissolved in 2-propanol (500 g) in a 1 L flask equipped with a stirrer and thermometer. To this stirred solution, a solution of tetraisopropoxide (45.4 g, 0.16 mol) in 2-propanol (200 g) was slowly added from a dropping funnel while maintaining the temperature in the system at 25 ° C. To this stirred mixture, a 32 wt / wt% aqueous NaOH solution (38.0 g, 0.30 mol) was slowly added from a dropping funnel while maintaining the temperature in the system at 25 ° C. The resulting product was filtered and 2-propanol / water was completely removed under vacuum to give a cloudy pale yellow product. This product was dissolved in 2-propanol (300 g) in a 5 L flask equipped with stirrer and thermometer. To this stirred solution was slowly added sodium hypophosphite (17.6 g, 0.20 mol) in 2-propanol (200 g) from a dropping funnel. To this mixture was added 4.0 kg of ethylene glycol, and a solution of ethylene glycol (500 g) in phosphoric acid (4.0 g, 0.04 mol) was slowly added from the dropping funnel while stirring. When stirred for 2 hours at 25 ° C. and normal pressure, an almost transparent liquid is formed. When 1.0 kg of this solution was filtered through a 0.2 μm filter, the weight R on the filter was 0.33 g, and the total weight S of the catalyst compound was 12.3 g. Therefore, the weight ratio Q of the filtered product in all the catalyst compounds was 2.68%. The catalyst compound had a titanium atom concentration of 12.5% by weight, and the number of titanium atoms in one molecule of the catalyst was 32.

B. Production method of polyethylene terephthalate A slurry of 100 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals) and 45 kg of ethylene glycol (manufactured by Nippon Shokubai Co., Ltd.) is charged with about 123 kg of bis (hydroxyethyl) terephthalate in advance, at a temperature of 250 ° C. and a pressure of 1.2 It supplied over 4 hours to the esterification reaction tank hold | maintained at * 10 < ⁵ > Pa, The esterification reaction was completed over 1 hour after completion | finish of supply. Next, 123 kg of this esterification reaction product was transferred to a polycondensation tank.

  Subsequently, 0.3% by weight was added to the polycondensation reaction tank to which the esterification reaction product had been transferred with respect to the polymer from which an ethylene glycol slurry of titanium oxide particles was obtained. After stirring for 5 minutes, 30 ppm in terms of cobalt atom and 15 ppm in terms of manganese atom were added to a polymer from which an ethylene glycol solution of cobalt acetate and manganese acetate was obtained. After further stirring for 5 minutes, the above catalyst solution was added to the obtained polymer so as to be 10 ppm in terms of titanium atom, and then the reaction system was heated to 250 ° C. to 285 ° C. while stirring the low polymer at 30 rpm. The pressure was gradually reduced to 40 Pa. The time to reach the final temperature and final pressure was both 60 minutes. When the predetermined stirring torque was reached, the reaction system was purged with nitrogen, returned to normal pressure, the polycondensation reaction was stopped, discharged into cold water in a strand form, and immediately cut to obtain polymer pellets. The time from the start of decompression to the arrival of the predetermined stirring torque was 3 hours.

  As shown in Table 1, the obtained polymer had an IV of 0.67, a solution haze of 0.5%, a small amount of foreign matter, a color tone L value of 74, a b value of 1.0, and a good color tone.

Comparative Examples 1 and 2
Catalyst preparation and polymerization were carried out in the same manner as in Example 1 except that the number of titanium atoms and the number of phosphorus atoms constituting the catalyst compound were different. As shown in Table 2, the color tone of the polymer was poor, and Comparative Example 2 had many foreign substances.

Comparative Examples 3 and 4
Catalyst preparation and polymerization were performed in the same manner as in Example 1 except that the ratio of the number of titanium atoms and the number of phosphorus atoms constituting the catalyst compound was different. In both cases, the color tone was very deteriorated. In Comparative Example 3, the progress of the polymerization was very slow because the catalyst was deactivated.

Examples 2-5
Catalyst preparation and polymerization were carried out in the same manner as in Example 1 except that the number of titanium atoms and the number of phosphorus atoms constituting the catalyst compound were different. As shown in Table 1, all had few foreign substances and gave a polymer having a good color tone.

Examples 6 and 7
Catalyst preparation and polymerization were performed in the same manner as in Example 1 except that the ratio of the number of titanium atoms and the number of phosphorus atoms constituting the catalyst compound was different. As shown in Table 1, all had few foreign substances and gave a polymer having a good color tone.

Examples 8-10
Catalyst preparation and polymerization were performed in the same manner as in Example 1 except that the phosphorus compound used for catalyst preparation was different. There was little foreign material and the polymer of favorable color tone was given.

Examples 11-13
Catalyst preparation and polymerization were performed in the same manner as in Example 1 except that the substituents bonded to titanium were different. There was little foreign material and the polymer of favorable color tone was given.

Examples 14-20
Catalyst preparation and polymerization were carried out in the same manner as in Example 1 except that the proportion of the phosphorus compound, the solvent composition, and the titanium atom concentration when the last part of the phosphorus compound was reacted were different. There was little foreign material and the polymer of favorable color tone was given.

Claims (10)

A catalyst for polyester polymerization, wherein the number of titanium atoms in one molecule of the catalyst compound is 20 or more and 200 or less, and the constituent molar ratio P of titanium atoms to phosphorus atoms satisfies the following formula (1).
(1) 0.5 <P <2.0   2. The polyester polymerization catalyst according to claim 1, wherein the catalyst compound is a reaction product of a titanium compound and a phosphorus compound.   3. The polyester polymerization catalyst according to claim 2, wherein the phosphorus compound comprises at least one selected from phosphoric acid compounds and at least one selected from phosphonic acid compounds and phosphinic acid compounds. The polyester polymerization according to any one of claims 1 to 3, wherein the substituent bonded to the titanium atom is at least one selected from the group consisting of functional groups represented by the following formulas 1 to 6. Catalyst.

(In Formula 1 to Formula 6, R _{1 to} R ₃ each independently have hydrogen, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group, a hydroxyl group, a carbonyl group, an acetyl group, a carboxyl group, an ester group, or an amino group. Represents a hydrocarbon group having 1 to 30 carbon atoms.)   The polyester polymerization catalyst according to claim 4, wherein the titanium atom substituent is at least one selected from hydroxycarboxylic acid compounds and polycarboxylic acid compounds.   When a dispersion of a catalyst compound having a titanium atom concentration of 1% by weight or less is filtered through a 0.2 μm filter, the ratio Q of the filtered product weight R to the total catalyst compound weight S is 20% or less. The catalyst for polyester polymerization according to any one of claims 1 to 5.   The method for producing a polyester polymerization catalyst according to any one of claims 2 to 6, wherein the phosphorus compound is reacted stepwise with the titanium compound.   8. The polyester according to claim 7, wherein in the step of reacting 70 mol% or more of the phosphorus compound, 80 wt% or more of the solvent is ethylene glycol, and the titanium atom concentration in the reaction system is 1 wt% or less. A method for producing a polymerization catalyst.   A method for producing a polyester, wherein the polymerization catalyst according to claim 1 is used.   The method for producing a polyester according to claim 9, wherein the polymerization catalyst according to claim 6 is added to the polymerization step.