JP2005290289A - Hardly precipitating titanium catalyst for manufacturing polyester and polyester obtained using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a catalyst for manufacturing polyesters, which does not contain a dissolution auxiliary, or the like, other than a phosphorous compound as a stabilizer, does not precipitate after catalyst preparation to accumulate or coagulate in a container or at the bottom of an apparatus, and is simple to handle. <P>SOLUTION: The catalyst for manufacturing polyesters comprises a reaction product of a titanium compound represented by formula (I) [wherein R<SB>1</SB>is a 1-12C alkyl group; and (q) is an integer of 1-4] with a phosphorous compound represented by formula (II) [wherein R<SB>2</SB>is a 1-18C alkyl group or a 6-12C aryl group; (m) and (p) are each an integer of 1-3; and (n) is an integer of at least 2]. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a catalyst for producing a polyester and a polyester using the same.

  Polyester is excellent in mechanical strength, heat resistance, transparency and gas barrier properties, and is suitably used as a material for films, sheets, fibers, etc. as well as materials for beverage filling containers such as juices, soft drinks or carbonated drinks. ing.

  Such a polyester is usually produced using aromatic dicarboxylic acids such as terephthalic acid and aliphatic diols such as ethylene glycol as raw materials. Specifically, a low-order condensate (ester low polymer) is first formed by an esterification reaction of an aromatic dicarboxylic acid and an aliphatic diol, and then this low-order condensate is removed in the presence of a polycondensation catalyst. Glycol reaction (liquid phase polycondensation) is used to increase the molecular weight. In some cases, solid phase polycondensation is performed to further increase the molecular weight.

  In the polyester production method, an antimony compound, a germanium compound, a titanium compound, or the like is conventionally used as a polycondensation catalyst. However, it is known that polyethylene terephthalate produced using an antimony compound as a catalyst is inferior to polyethylene terephthalate produced using a germanium compound as a catalyst in terms of transparency and heat resistance. Moreover, since the germanium compound is quite expensive, there is a problem that the production cost of the polyester is increased. For this reason, in order to reduce the manufacturing cost, a process of recovering and reusing the germanium compound scattered during polycondensation has been studied.

  Further, titanium compounds are known to be compounds having an action of promoting ester polycondensation reaction, and titanium alkoxide, titanium tetrachloride, titanyl oxalate or orthotitanic acid are known as polycondensation catalysts. Many studies have been made to use such a titanium compound as a polycondensation catalyst. However, when conventional titanium compounds are used as polycondensation catalysts, they are more active than antimony compounds and germanium compounds, but they are poorly soluble in solvents. There is a problem that it is easy.

  Regarding a titanium catalyst for polyester production, a solid titanium catalyst obtained by hydrolysis of a titanium compound is heated at 120-200 ° C. with addition of ethylene glycol, a dissolution aid such as glycerin, and an acid component such as sulfuric acid. A method for obtaining an ethylene glycol solution having a concentration of 3000 to 10000 ppm in terms of titanium atom by dissolution is described (for example, see Patent Document 1). However, this method requires a very cumbersome processing step such as hydrolysis and dehydration drying to prepare a solid titanium catalyst, and also requires extra additives such as a dissolution aid and an acid component. When producing polyethylene terephthalate resin for beverage filling containers, there are concerns about the adverse effects on elution into flavored beverages and flavor properties.

  In addition, a technique for obtaining a yellow transparent solution by adding an aqueous sodium hydroxide solution to a mixed solution of titanium butoxide and ethylene glycol has also been introduced (see, for example, Patent Document 2). However, it is widely known that the presence of alkali metal elements or alkaline earth metal elements adversely affects the hue of the polyester resin. In fact, the hue of polyethylene terephthalate obtained in Patent Document 2 is extremely strong in yellow with a minimum b value of 3.7, and is not suitable as a molding material for beverage filling containers. Moreover, as a molding material of a drink filling container, it is also desired to reduce the acetaldehyde content in the obtained polyester.

International Publication No. 02/016467 Pamphlet International Publication No. 00/071252 Pamphlet

  An object of the present invention is to provide a titanium catalyst for polyester production that does not contain a solubilizing agent other than a phosphorus compound that is a stabilizer, and that is precipitated after preparation of the catalyst and does not accumulate and condense at the bottom of the container or apparatus, and is easy to handle. Is to provide.

［上記式中、Ｒ_１は１〜１２個の炭素原子を有するアルキル基を、ｑは１〜４の整数を表す。］
と下記一般式（ＩＩ）で表されるリン化合物

［上記式中、Ｒ_２は１〜１８個の炭素原子を有するアルキル基または６〜１２個の炭素原子を有するアリール基を表す。ｍ及びｐは１〜３の整数、ｎは２以上の整数を表す。］
との反応生成物からなるポリエステル製造用触媒によって解決することができる。 In order to solve the above-mentioned problems, the present inventors have intensively studied polycondensation catalysts used in the production of polyester. As a result, specific titanium compounds and phosphorus compounds are used as raw materials, and these reaction products are used as polycondensation catalysts. As a result, it has been found that a high-quality polyester with high catalytic activity can be produced without precipitation after the catalyst preparation and deposition and condensation at the bottom of the container / equipment. That is, the above problem is a titanium compound represented by the following general formula (I)

[In the above formula, R ₁ represents an alkyl group having ₁ to 12 carbon atoms, and q represents an integer of 1 to 4. ]
And a phosphorus compound represented by the following general formula (II)

[Wherein R ₂ represents an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 12 carbon atoms. m and p represent an integer of 1 to 3, and n represents an integer of 2 or more. ]
This can be solved by a polyester production catalyst comprising a reaction product of

  According to the catalyst for polyester production according to the present invention, compared to conventional titanium compound catalysts, it is easy to handle because it does not settle after the catalyst preparation, and does not accumulate or condense at the bottom of the container / equipment, and the catalyst is metered during polyester production. Etc. can be expected to become easier. Further, the above deposits / condensates are not mixed in the polyester.

Hereinafter, the present invention will be described in detail.
(catalyst)
The catalyst for producing the polyester of the present invention can be obtained by mixing and reacting a titanium compound and a phosphorus compound described later.
It is necessary to use a compound represented by the following formula (I) as the titanium compound.

［上記式中、Ｒ_１は１〜１２個の炭素原子を有するアルキル基を、ｑは１〜４の整数を表す。］

[In the above formula, R ₁ represents an alkyl group having ₁ to 12 carbon atoms, and q represents an integer of 1 to 4. ]

Specifically, it is preferable to use at least one titanium compound selected from the group consisting of titanium tetra-n-propoxide, titanium tetraisopropoxide and titanium tetrabutoxide, more preferably titanium tetraisopropoxide.
Moreover, as a phosphorus compound, it is necessary to use the compound represented by following formula (II).

［上記式中、Ｒ_２は１〜１８個の炭素原子を有するアルキル基または６〜１２個の炭素原子を有するアリール基を表す。ｍ及びｐは１〜３の整数、ｎは２以上の整数を表す。］

[Wherein R ₂ represents an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 12 carbon atoms. m and p represent an integer of 1 to 3, and n represents an integer of 2 or more. ]

Of these, compounds with larger p are considered preferable. These phosphorus compounds may be used alone or in combination of two or more. In particular, butoxyethyl acid phosphate (in the above formula (II), R ₂ is a butyl group, n = 2, p = 1, m = 1, 2 in terms of easy production and industrial availability) Is preferred). By using this phosphorus compound, it is considered that precipitation is generated after catalyst adjustment and volume / condensation at the bottom of the container or the like can be suppressed. Although the details of the cause are unknown, it is considered that the affinity with glycol used for dispersion is related.

  The catalyst for producing the polyester of the present invention can be obtained by mixing and reacting the above-described titanium compound and phosphorus compound. However, when the catalyst of the present invention is produced, if the production method such as the compounding ratio of the titanium compound and the phosphorus compound, the reaction method and the reaction conditions are not appropriate, the reaction does not occur sufficiently and many unreacted titanium compounds and unreacted Of phosphorus compounds. Accordingly, the production method for efficiently reacting the catalyst for producing the polyester of the present invention to obtain a high content will be described in more detail below.

  The catalyst for producing the polyester of the present invention can be produced by heating the above titanium compound and phosphorus compound using glycol as a medium. At this time, the glycol solution of the titanium compound and the glycol solution of the phosphorus compound are homogeneous transparent solutions, respectively. When both are mixed and heated, the titanium compound and the phosphorus compound react, and the reaction product is obtained as a suspension in the glycol. It is done.

  Examples of the glycol used here include ethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol, and cyclohexanedimethanol. As the glycol used for the production of the catalyst, it is preferable to use the same glycol as the raw material of the polyester produced using the catalyst produced thereafter.

  The reaction temperature is preferably at a temperature of 50 ° C. to 200 ° C., and the reaction time is usually 1 minute to 4 hours. It is preferable to complete.

  For example, when ethylene glycol is used as the glycol, 50 ° C. to 150 ° C. is preferable, and when hexamethylene glycol is used, 100 ° C. to 200 ° C. is a preferable range, and the reaction time is more preferably 30 minutes to 2 hours. If the reaction temperature is too high or the time is too long, the catalyst will deteriorate, which is not preferable.

  In reacting the catalyst, the molar ratio of phosphorus atom to titanium atom is preferably 1.5 or more and less than 2.5, and more preferably 1.7 or more and less than 2.3. On the other hand, if it is less than 1.5, many unreacted titanium compounds exist, and conversely, if it is 2.5 or more, many excessive unreacted phosphorus compounds exist.

  In the case of producing a polyester, particularly an aromatic polyester using the catalyst of the present invention, it is preferably used as a catalyst in an amount of 1 to 50 ppm in terms of titanium metal atom in the finally obtained polyester, More preferably, it is used in an amount of 5 to 30 ppm. And as a metal atom in the polyester obtained, metal atoms other than titanium are preferably 10 ppm or less, more preferably 5 ppm or less in terms of metal element concentration.

  In addition, the said reaction product should just exist at the time of a polycondensation reaction. Therefore, the catalyst may be added in any step such as a raw material slurry preparation step, an esterification step or a liquid phase polycondensation step. Further, the entire amount of the catalyst may be added at once, or may be added in a plurality of times.

(Production method of polyester)
Next, the manufacturing method of polyester using the catalyst of this invention is demonstrated. A polyester can be produced by polycondensation of an aromatic dicarboxylic acid or an ester-forming derivative thereof and an aliphatic glycol using the catalyst of the present invention.

(material)
As the aromatic dicarboxylic acid, for example, terephthalic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid or an ester-forming derivative thereof can be used. Examples of ester-forming derivatives include lower alkyl esters and acid halides. Among these, it is preferable to use terephthalic acid or an ester-forming derivative thereof. As the aliphatic glycol, for example, ethylene glycol, trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexanemethylene glycol or dodecamethylene glycol can be used. Among these, it is preferable to use ethylene glycol. These aromatic dicarboxylic acids, their ester-forming derivatives and aliphatic glycols may be used singly or in combination.

  Along with the aromatic dicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid or decanedicarboxylic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid or ester-forming derivatives thereof can be used as raw materials. In addition to aliphatic glycols, alicyclic glycols such as cyclohexanedimethanol, diols containing aromatic groups such as bisphenol, hydroquinone or 2,2-bis (4-β-hydroxyethoxyphenyl) propane may be used as raw materials. it can. Furthermore, polyfunctional compounds such as trimesic acid, trimethylolethane, trimethylolpropane, trimethylolmethane, or pentaerythritol can be used as a raw material.

  Of these, terephthalic acid or an ester-forming derivative thereof is used in such an amount that it is 80 mol% or more, preferably 90 mol% or more with respect to 100 mol% of the aromatic dicarboxylic acid or its ester-forming derivative. The ethylene glycol is preferably used in an amount of 80 mol% or more, preferably 90 mol% or more with respect to 100 mol% of the aliphatic glycol.

(Esterification process)
First, when manufacturing polyester, aromatic dicarboxylic acid or its ester-forming derivative and aliphatic glycol are esterified. The case where an aromatic dicarboxylic acid and an aliphatic glycol are esterified will be described below. Specifically, a slurry containing an aromatic dicarboxylic acid and an aliphatic glycol is prepared. Such a slurry usually contains 1.1 to 1.6 mol, preferably 1.2 to 1.4 mol, of aliphatic glycol per mol of aromatic dicarboxylic acid. This slurry is continuously supplied to the esterification reaction step.

  The esterification reaction is preferably performed in a single stage because the reactants are not recirculated, or a method in which two or more esterification reactors are connected in series, both of which are under conditions where the aliphatic glycol is refluxed. It is carried out while removing water produced by the reaction from the system with a rectification column. Here, in using the catalyst of the present invention, as described above, it is preferably used as a catalyst in an amount of 1 to 50 ppm in terms of titanium metal atom in the finally obtained polyester, and becomes 5 to 30 ppm. More preferably, it is used in an amount.

  The reaction conditions when the esterification is carried out continuously in one stage without allowing the reactants to self-circulate are usually a reaction temperature of 240 to 280 ° C, preferably 250 to 270 ° C, and a reaction pressure of normal pressure to 0.3 MPa. It is desirable to carry out the reaction until the esterification rate is usually 90% or higher, preferably 95% or higher. Even in the case of using an ester-forming derivative of an aromatic dicarboxylic acid, it can be esterified by a method according to this.

  By this esterification step, an esterification reaction product (oligomer) of an aromatic dicarboxylic acid and an aliphatic glycol is obtained, and the degree of polymerization of this oligomer is preferably about 4 to 10. The oligomer obtained in the esterification step as described above is then supplied to a polycondensation (liquid phase polycondensation) step.

(Liquid phase polycondensation process)
Next, in the liquid phase polycondensation step, in the presence of the polycondensation catalyst of the present invention, the oligomer obtained in the esterification step is heated under reduced pressure to a temperature not lower than the melting point of the polyester (usually 240 to 280 ° C.). To polycondense. This polycondensation reaction is desirably carried out while distilling off unreacted aliphatic glycol and aliphatic glycol generated by polycondensation outside the reaction system.

  The polycondensation reaction may be performed in one tank or may be performed in a plurality of tanks. For example, when the polycondensation reaction is performed in two stages, the polycondensation reaction in the first tank has a reaction temperature of 245 to 290 ° C, preferably 260 to 280 ° C, and a pressure of 100 to 1 kPa, preferably 50 to 2 kPa. The polycondensation reaction in the final second tank is carried out under the conditions of 265 to 300 ° C., preferably 270 to 290 ° C., and the reaction pressure is usually 1000 to 10 Pa, preferably 500 to 30 Pa. Done in

  In this way, a polyester can be produced using the catalyst of the present invention. The polyester obtained in this polycondensation step is usually granulated (chip-shaped) after cooling while being extruded in a molten state. The intrinsic viscosity IV of the obtained polyester is 0.40 to 0.80 dl / g, preferably 0.50 to 0.70 dl / g.

(Solid phase polycondensation process)
The polyester obtained in the liquid phase polycondensation step is preferably further subjected to solid phase polycondensation when a polyester having a high intrinsic viscosity is desired. The granular polyester supplied to the solid phase polycondensation step may be supplied to the solid phase polycondensation step after preliminarily crystallizing by heating to a temperature lower than the temperature in the case of performing solid phase polycondensation in advance.

  Such a precrystallization step can be performed by heating the granular polyester in a dry state at a temperature of usually 120 to 200 ° C., preferably 130 to 180 ° C. for 1 minute to 4 hours. Such pre-crystallization can also be performed by heating the granular polyester at a temperature of 120 to 200 ° C. for 1 minute or more in a steam atmosphere, a steam-containing inert gas atmosphere, or a steam-containing air atmosphere. The precrystallized polyester desirably has a crystallinity of 20 to 50%. The so-called polyester solid phase polycondensation reaction does not proceed by this precrystallization treatment, and the intrinsic viscosity of the precrystallized polyester is almost the same as the intrinsic viscosity of the polyester after liquid phase polycondensation. The difference between the intrinsic viscosity of the crystallized polyester and the intrinsic viscosity of the polyester before pre-crystallization is usually 0.06 dl / g or less.

  The solid phase polycondensation step comprises at least one stage, temperature is 190 to 230 ° C., preferably 195 to 225 ° C., pressure is 200 kPa to 1 kPa, preferably normal pressure to 10 kPa, and nitrogen, argon or carbonic acid. It is performed under an inert gas atmosphere such as gas. Nitrogen gas is desirable as the inert gas used.

  The granular polyester obtained through such a solid-phase polycondensation step may be subjected to water treatment as necessary, and this water treatment is performed by treating the granular polyester with water, steam, steam-containing inert gas or steam-containing polyester. It is performed by contacting with air or the like.

  The intrinsic viscosity IV of the granular polyester thus obtained is preferably 0.70 dl / g or more. The production process of the polyester including the esterification step and the polycondensation step as described above can be performed by any of batch type, semi-continuous type and continuous type.

  In particular, polyethylene terephthalate that undergoes solid phase polycondensation is generally used in bottles and the like. For this reason, it is preferable that IV is 0.70 dl / g or more and that the acetaldehyde content is low.

  In addition, since the acetaldehyde content in polyethylene terephthalate is usually reduced in the solid phase polycondensation step, it can be dealt with by adjusting the melt condensation IV before solid phase polycondensation, the conditions of solid phase polycondensation, and the like.

  Therefore, the polyethylene terephthalate obtained by the above method is excellent in hue and transparency and has a low acetaldehyde content, and is useful as a molded material for bottles and the like. Specifically, when the catalyst of the present invention is used, the haze of the body of the preform molded body obtained by molding is usually 10% or less, preferably 0 to 5%, and the content of acetaldehyde is 30 ppm or less, Preferably it can be 25 ppm or less.

Hereinafter, the present invention will be described in more detail with reference to examples. Various analytical evaluations were performed as follows.
* Intrinsic viscosity (IV)
After 0.6 g of polyester was dissolved by heating in 50 cc of O-chlorophenol, the polyester was once cooled, and the solution was calculated from the solution viscosity measured at 35 ° C. using an Ubbelohde viscometer.
* Hue (Col)
The granular polymer sample was heat-treated in a dryer at 160 ° C. for 90 minutes, crystallized, and then measured with a CM-7500 color machine manufactured by Color Machine Co. The sample after the solid phase polycondensation was measured in the same manner without the heat treatment step.
O Diethylene glycol (DEG) content The sample was decomposed with hydrazine hydrate (hydrated hydrazine) and measured by gas chromatography (GC).
〇 Haze of the molded product Sampling the central part of the length of the preform body of any one sample after the fifth shot after the start of injection molding, the turbidimeter (HDH manufactured by Nippon Denshoku Industries Co., Ltd.) -1001 DP).
Acetaldehyde (AA) content The AA content was measured by Hitachi headspace gas chromatography by freezing and crushing a sample, placing it in a vial, holding it at 150 ° C for 60 minutes, and then making it.
〇Metal content concentration analysis The catalyst metal concentration in polyester is obtained by heating and melting a granular sample on an aluminum plate, and then forming a molded body having a flat surface with a compression press machine. Fluorescent X-ray device (Rigaku Corporation 3270E type) And quantitative analysis.

[Example 1]
437 parts by weight of ethylene glycol and 6 parts by weight of butoxyethyl acid phosphate (mixture of monoester [m = 1] and diester [m = 2] in a weight ratio of 4: 6) were mixed and stirred, and titanium tetraisopropoxy was added. 57 parts by weight of an ethylene glycol solution (titanium concentration 1% by weight) was slowly added, the temperature was gradually raised and the mixture was stirred at 100 ° C. for 1 hour, and then the resulting suspension was allowed to cool to room temperature. (Hereinafter, this suspension is abbreviated as “BEP catalyst”). When 100 mL of this liquid was collected in a 100 mL graduated cylinder and allowed to stand for 120 hours, a transparent supernatant liquid was produced in a 45 mL volume portion from the liquid surface, but the catalyst particles were suspended in the 55 mL volume portion at the bottom. There was no precipitation or condensation.

[Comparative Example 1]
The phosphorus compound in Example 1 was almost the same apparatus except that 3.7 parts by weight of monobutyl phosphate was used instead of 6 parts by weight of butoxyethyl acid phosphate (a mixture of a monoester and a diester in a weight ratio of 4: 6). And the procedure was carried out. When 100 mL of this liquid was collected in a 100 mL graduated cylinder and allowed to stand for 120 hours, a transparent supernatant liquid was generated in a 94 mL volume portion from the liquid surface, and catalyst particles were precipitated and condensed in a bottom 6 mL volume portion. The agglomerates did not disperse again when shaken.

[Example 2]
179 parts by weight of high-purity terephthalic acid and 95 parts by weight of ethylene glycol were mixed in a reactor in which 225 parts by weight of the oligomer had been retained in advance under the condition of being maintained at 255 ° C. and normal pressure in a nitrogen atmosphere under stirring. The slurry prepared in this manner was supplied at a constant rate, and the esterification reaction was completed for 4 hours while water and ethylene glycol generated by the reaction were distilled out of the system to complete the reaction. The esterification rate at this time was 98% or more, and the polymerization degree of the produced oligomer was about 5 to 7.

  225 parts by weight of the oligomer obtained by this esterification reaction was transferred to a polycondensation reaction tank, and 1.8 parts by weight of the titanium / phosphorus reaction compound suspension (BEP catalyst) prepared in Example 1 was added as a polycondensation catalyst. did. Subsequently, the polycondensation reaction is carried out while the reaction temperature in the system is gradually increased and reduced from 255 to 280 ° C. and the reaction pressure is gradually increased from normal pressure to 60 Pa, and water and ethylene glycol generated in the reaction are removed from the system. went.

  The progress of the polycondensation reaction was confirmed without monitoring the load on the stirring blades in the system, and the reaction was terminated when the desired degree of polymerization was reached. Thereafter, the reaction product in the system was continuously extruded in a strand form from the discharge part, cooled and cut to obtain granular pellets having a size of about 3 mm. The polycondensation reaction time at this time was 110 minutes. The obtained polyethylene terephthalate had an IV of 0.515 dl / g, a DEG of 1.14% by weight, a Col-L value of 82, and a b value of 0.6, and the catalyst metal concentration contained was 13 ppm titanium and 14 ppm phosphorus.

[Example 3]
The polyethylene terephthalate obtained in Example 2 was crystallized and dried at 160 ° C. for 4 hours under a nitrogen flow in a shelf-type crystallizer. Subsequently, it was transferred to a tumbler type solid phase polymerization tower, and solid phase polycondensation was performed at 215 ° C. for 27 hours under a nitrogen flow. The polyethylene terephthalate thus obtained had an IV of 0.741 dl / g, a Col-L value of 85, and a b value of 2.2.

Further, a preform molded body was molded by the following method using these solid phase polycondensed polyethylene terephthalate. 5 kg of polyethylene terephthalate was dried for 10 hours or more under conditions of 160 ° C., normal pressure and N ₂ inflow using a shelf type dryer, and the dried polyethylene terephthalate was injection molded (“M-100DM” manufactured by Meiki Seisakusho Co., Ltd.). ), Cylinder temperature 275 ° C., screw rotation speed 160 rpm, primary pressure time 3.0 seconds, mold cooling temperature 10 ° C., cycle 30 seconds, outer diameter about 28 mm, inner diameter about 19 mm, length 136 mm, body part A cylindrical preform having a wall thickness of 4 mm and a weight of about 56 g was injection molded. The center part of the trunk portion of each obtained preform was sampled, and the IV, haze, and acetaldehyde concentrations were measured. The results were IV 0.662 dl / g, haze 1.6%, and acetaldehyde 15.7 ppm. Further, when the preform molded body was closely observed with the naked eye, no foreign matter attributable to the catalyst particles was found.

  According to the present invention, it is possible to obtain a polyester production catalyst which is easy to handle and does not precipitate after the catalyst is prepared and does not accumulate or condense at the bottom of the container or apparatus. When this catalyst is used, the handling is simpler than conventional titanium compound catalysts, so that the measurement of the catalyst during the production of the polyester is facilitated, and the polyester can be produced more efficiently.

  Polyesters produced with the catalyst of the present invention do not contain solubilizing agents other than phosphorus compounds that are stabilizers, and can provide molded articles with less haze, less heavy metal and acetaldehyde content, and less foreign matter. Therefore, it is useful as a material for a molded container for beverage filling bottles.

Claims (3)

Titanium compound represented by the following general formula (I)

[In the above formula, R ₁ represents an alkyl group having ₁ to 12 carbon atoms, and q represents an integer of 1 to 4. ]
And a phosphorus compound represented by the following general formula (II)

[Wherein R ₂ represents an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 12 carbon atoms. m and p represent an integer of 1 to 3, and n represents an integer of 2 or more. ]
A catalyst for producing polyester comprising a reaction product of   The catalyst for producing a polyester according to claim 1, wherein the titanium compound of the formula (I) is a titanium compound selected from the group consisting of titanium tetra-n-propoxide, titanium tetraisopropoxide and titanium tetrabutoxide.   A polyester produced using the catalyst according to claim 1.