JP2000086751A - Catalyst for polymerizing polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject catalyst excellent in catalytic actions on a condensation polymerization at the time of synthesizing a polyester such as polyethylene terephthalate and having actions of suppressing a thermal decomposing reaction occurring as a side reaction by composing the catalyst of a specific organic ligand-containing metal complex compound. SOLUTION: This catalyst contains a central metal which is one or more kinds selected from preferably Bi, Fe, Cu, etc. of an organic ligand-containing metal complex compound π-coordinated with the ester plane of a polyester. The shape of the lowest unoccupied molecular orbital obtained by calculating the molecular orbital of the metal complex compound is preferably the p-type or d-type. The metal complex compound preferably has the organic ligand coordinating with the central metal and containing oxygen atoms. Furthermore, >=2 of the oxygen atoms are preferably bound to the central metal. When producing the polyester, the catalyst is preferably added in an amount of 0.2-500 ppm expressed in terms of the central metal based on the resultant polyester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal complex compound which catalyzes condensation polymerization during polyester synthesis, and a method for producing polyester.

[0002]

2. Description of the Related Art Polyesters are widely used in various fields such as fibers, films and bottles because of their excellent properties. Among them, polyethylene terephthalate is preferably used because of its excellent mechanical strength, chemical properties, dimensional stability and the like.

[0003] Generally, polyethylene terephthalate is produced from terephthalic acid or an ester-forming derivative thereof and ethylene glycol. In a commercial process for producing a polymer having a high molecular weight, tetraethylene is used as a catalyst to be added at the time of condensation polymerization during polyester synthesis. Titanium compounds such as butyl titanate are widely used. However, polymers containing titanium compounds have some disadvantages as described below.

[0004] The titanium compound has an extremely high catalytic activity for the polymerization reaction, but also has a very large effect of promoting thermal decomposition. For this reason, the color tone of the obtained polymer is deteriorated, and the molecular weight of the polymer is greatly reduced when the polymer is re-melted in a molding process such as a yarn-forming process or a film-forming process.

[0005] With respect to the drawback relating to the color tone, proposals have been made to use a titanium compound and phosphoric acid together, to use a titanium compound and a cobalt compound together, and to use a titanium compound, a cobalt compound and an alkali metal compound together. The above drawbacks have not been sufficiently improved. Moreover, these methods cannot prevent thermal decomposition during remelting.

[0006] From the background described above, a compound having a catalytic action that can be substituted for a titanium compound in condensation polymerization at the time of polyester synthesis is required.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of polyesters produced by using a titanium compound as a catalyst, and at the same time, to comprise a metal complex compound having a catalytic activity at least as high as these compounds. A catalyst for condensation polymerization is provided.

[0008]

In order to solve the above-mentioned problems, the present invention has the following arrangement. 1. 1. A catalyst for polyester polymerization, which is a metal complex compound, wherein the central metal of the compound is π-coordinated to the ester surface of the polyester. 2. The catalyst for polyester polymerization, which is a metal complex compound, wherein the shape of the lowest unoccupied molecular orbital obtained by molecular orbital calculation is p-type or d-type. "The central metal in the metal complex compound is In, Tl, A
Any of the foregoing polyester polymerization catalysts, which is at least one selected from s, Bi, Se, Te, Fe and Cu. 4. 4. The catalyst for polyester polymerization according to any one of the above, which is a metal complex compound and has an organic ligand coordinated to a central metal. "A metal complex compound, wherein the organic ligand coordinated to the central metal contains an oxygen atom, and at least two or more of the oxygen atoms are bonded to the central metal according to the constitution 3 or 4 per center. 5. The polyester polymerization catalyst according to any one of the above, wherein 6. A method for producing a polyester, wherein a polymerization reaction is carried out by adding any of the above-mentioned catalysts for polyester polymerization to a raw material of the polyester. 7. "The method for producing the polyester, wherein the polyester has a structural unit derived from an aromatic dicarboxylic acid." 8. A method for producing any of the above polyesters, wherein the polyester is polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polyethylene naphthalate or polypropylene naphthalate. 9. The method for producing any of the above polyesters, wherein the raw material of the polyester is an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol, or a low molecular weight polyester oligomer thereof. "A method for producing any one of the polyesters described above, wherein the amount of the polymerization catalyst to be added is 0.2 to 500 ppm with respect to the polyester obtained in terms of a central metal".

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

In the present invention, when the metal complex compound of the present invention is added during or before the condensation polymerization,
Compared with the case where no addition is made, a metal complex compound having a catalytic action such as a higher degree of polymerization of the polyester obtained by condensation polymerization or a reduction in the condensation polymerization time until a predetermined degree of polymerization is reached is observed. It is called a polymerization catalyst. When the above change is observed, the metal complex compound is said to have catalytic activity. Further, the metal complex compound can be used catalytically during the polyester polymerization reaction,
It is not necessary that the composition of the metal complex compound be the same before and after the polymerization reaction.

The coordination structure of the ester to the metal complex compound is
According to the result of ab initio molecular orbital calculation described later in the section of Examples, σ configuration and π configuration exist.

In the present invention, the sigma coordination refers to the coordination structure between the metal atom in the metal complex compound and the polyester.
It refers to a coordination structure in which the elevation angle formed by carbonyl carbon-carbonyl oxygen-the metal atom with respect to the coordinating ester surface is less than 90 degrees. In addition, the π configuration is a configuration structure in which the elevation angle is 90 degrees or more.

A polyester obtained as a result of adding a metal complex compound in which the coordination state of the ester to the metal atom is in the π-coordinate during the condensation polymerization is preferable because a decrease in molecular weight caused by thermal decomposition upon re-melting of the polymer is small. . On the other hand, polyesters using a titanium compound having a coordination state of σ as a catalyst are not preferred because the molecular weight is significantly reduced by thermal decomposition. That is, the metal complex compound of the present invention has an effect of suppressing a thermal decomposition reaction of the polyester, and has a preferable property as a polyester polymerization catalyst.

In the present invention, the p-type lowest unoccupied molecular orbital means that the lowest unoccupied molecular orbital localized on the central metal is one.
Refers to one having three clauses. In addition, the d-type lowest unoccupied molecular orbital refers to an orbital having two nodes. On the other hand, the s-type refers to one whose trajectory has no nodes.

In order to reduce the decrease in molecular weight due to thermal decomposition, it is preferable that the lowest unoccupied orbital is p-type or d-type. If the lowest unoccupied orbit is of the s-type, the molecular weight decrease due to thermal decomposition is undesirably large.

In order for the metal complex to have the above characteristics, the central metal element of the metal complex is In, Tl, A
It is preferably at least one selected from s, Bi, Se, Te, Fe and Cu. More preferably, it is Bi, Fe, and Cu, and still more preferably Bi.

Further, when an organic ligand containing an oxygen atom is used as an organic ligand which coordinates to the central metal element, when the metal complex compound is dispersed in a diol such as ethylene glycol which is a raw material of polyester, the conversion to glycolate is prompt. The dispersibility is improved by progressing to the above, which is particularly preferable.

The metal complex compound containing an organic ligand of the present invention is
It is possible to add it alone during the condensation polymerization, but it is also possible to use a mixture of two or more. At this time, the sum of each metal atom is 0.2 ppm with respect to the polymer.
It is necessary to add and contain not less than 500 ppm.
More preferably, it is 1 ppm or more and 200 ppm or less, and still more preferably 1 ppm or more and 100 ppm or less. If the amount added is less than 0.2 ppm, the catalytic activity is insufficient, and the molecular weight of the resulting polymer is low, resulting in insufficient strength of the molded product. If added in an amount exceeding 500 ppm, foreign matter is generated, and the filtration pressure during molding becomes remarkable and the color tone of the polymer deteriorates.

In the polyester synthesis method of the present invention, first, the dicarboxylic acid and the diol are esterified, or the ester-forming derivative of the dicarboxylic acid is transesterified with the diol.

Specific examples of the dicarboxylic acid used in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid and diphenyldicarboxylic acid; alicyclic rings such as decalin dicarboxylic acid and hexahydroterephthalic acid. Aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid and sebacic acid;

Specific examples of the diol used in the present invention include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1, 5-pentanediol, 1,6-hexanediol, 1,8-
Octanediol and the like.

The polyester synthesized from the above-mentioned dicarboxylic acids and diols by adding the organic ligand-containing metal complex compound of the present invention at the time of condensation polymerization is, for example, polyethylene terephthalate, polypropylene terephthalate, or the like. Examples thereof include polybutylene terephthalate, polyethylene naphthalate, polypropylene naphthalate, polybutylene naphthalate, and copolymers and modified products thereof. The metal complex compound containing an organic ligand of the present invention exhibits a high effect in polyethylene terephthalate.

The esterification reaction in the present invention is usually carried out
A dicarboxylic acid and a diol are used in a molar ratio of dicarboxylic acid / diol within a range of 1/1 to 1/2.
Under a pressure of about 400,000 Pa or less in a temperature range of ~ 250 ° C,
The distillation is performed until the esterification reaction rate becomes about 95% or more while distilling out the generated water from the system. In the transesterification, the dicarboxylic acid ester-forming derivative and the diol are usually used in a molar ratio of dicarboxylic acid ester-forming derivative / diol of 1/1 to 1/3, and
The transesterification rate is about 98% or more while distilling out by-products such as alcohol and phenol from the system under an atmospheric pressure in an inert gas atmosphere such as nitrogen gas in a temperature range of from 0 ° C to 240 ° C. You just need to do it.

The reaction mixture containing a low polymer such as bis (β-hydroxyethyl) terephthalate obtained by the above esterification reaction or transesterification reaction is then subjected to a condensation polymerization reaction.

In the present invention, the condensation polymerization reaction is carried out at about 130
It can be carried out by a melt polymerization method under a reduced pressure of 0 Pa or less and in a temperature range of about 230 to 290 ° C. For the purpose of obtaining a polyester having a higher polymerization degree, solid-state polymerization can be performed subsequent to melt polymerization. In this case, the polymer obtained by the melt polymerization is solidified and formed into a chip having an arbitrary shape such as a dice shape or a cylindrical shape.
After pre-drying at a temperature of 90 ° C or less, while flowing,
It is desirable to carry out solid phase polymerization at a temperature in the range of about 190 ° C. to 240 ° C. under a reduced pressure of about 1300 Pa or less or under a flow of an inert gas such as nitrogen gas.

The calculation method and physical property evaluation method used in the present invention will be described below.

1. Molecular orbital calculation (1) Method of ab initio molecular orbital calculation For typical elements, the restricted Hartree-Fock method (R
HF method). For the transition metal element, the unrestricted Hartree-Fock method (UHF method) was used. (2) Basis Set The basis set is a 6-31G ** basis set for hydrogen, carbon, oxygen and nitrogen atoms, which is indicated by Pople et al. (R. Ditchfield, W. J. Here, JA Pople, Journal of Chemical Physics, 54, 724 (1971) (R. Ditchfield, WJHehre, JAPop)
le, J. Chem. Phys., vol. 54, p. 724 (1971)). For other atoms, the basis set shown by Fujinaga et al. (Gaussian Basis Set for Molecular Calculation, Fujinaga, Elsevier (1984); gaussian basis sets for molecu
lar calculations, ed. by S. Huzinaga et al., Elsevi
er (1984)). (3) Determination of molecular structure The molecular structure of the metal complex compound is determined by the energy gradient method.
The molecular structure of the ester and the coordination structure of the metal complex compound to the ester were optimized. At that time, a plurality of calculations were performed while changing the initial structure, and the most stable one of the obtained results was used as the molecular structure. (4) Executing ab initio molecular orbital calculation As the calculation software, Gaussian9 manufactured by Gaussian Inc.
4 was used. FOpt was used as the keyword for optimization.
The convergence condition of the SCF calculation was 0.1 kcal / mol, and the convergence condition of the force of the structure optimization calculation was 8.0 × 10 ⁻¹⁸ N. The parameters required for other calculations used the standard values of the software. (5) Visualization of molecular orbitals To visualize the molecular orbitals obtained as a result of molecular orbital calculations, use Mo
Cerius2 manufactured by Lecular Simulations Inc. was used.

(6) Hardware The molecular orbital calculation was performed on an engineering workstation manufactured by Digital Equipment Corporation. For visualization of molecular orbitals, an engineering workstation manufactured by Silicon Graphics was used.

2. Metal Complex Compound Used The following metal acetates were used.

Bi (compound 1), Fe (compound 2), T
2. i (compound 3), Al (compound 4), Zr (compound 5) Intrinsic viscosity [η] (unit: dl / g) of polymer was measured at 25 ° C. using orthochlorophenol as a solvent.

4. Reduction of molecular weight upon remelting of polymer After pelletized polymer was dried at 150 ° C. and 1 torr or less for 20 hours or more, it was heat-treated at 290 ° C. for 5 hours in a nitrogen atmosphere, and the intrinsic viscosity reduction (ΔIV) at that time was determined by the formula Determined by 1).

ΔIV = (intrinsic viscosity before heat treatment) − (intrinsic viscosity after heat treatment) (Formula 1)

[0033]

The present invention will be described in more detail with reference to the following examples. In addition, Comparative Examples 1 to 3 described below are examples of known catalysts.

Bi and Fe were selected as the central metal elements of the metal complex compound, and Ti, Al, and Zr were selected as comparative examples, and ab initio molecular orbital calculations were performed. In the metal complex compound in which the central metal element in the metal complex compound is Bi or Fe, the coordination structure to the ester has the most stable σ coordination structure, but the metal complex compound in which the metal element is Ti, Al, or Zr In this case, the π configuration became the most stable structure. Table 1 shows the coordination state and the shape of the lowest unoccupied molecular orbital.

Further, a polyester was synthesized using the metal complex compound as a catalyst for condensation polymerization and heat-treated. A low-polymer such as bis (β-hydroxyethyl) terephthalate, which does not contain a catalyst, produced from high-purity terephthalic acid and ethylene glycol according to a conventional method is melted at 250 ° C., and (Molecule 1) to (Molecule 5) are added to the melt. ) Was added dispersed in ethylene glycol. The amount of each organic ligand-containing metal complex compound added was as shown in Table 1 as the content of the central metal element in the polymer finally obtained. Then, while stirring the low polymer at 30 rpm, the reaction system was heated from 250 ° C to 2 ° C.
Gradually raise the temperature to 85 ° C and reduce the final pressure to 40P
a. The time to reach the final temperature and the final pressure was all 60 minutes. When the stirring torque reached a predetermined value, the reaction system was purged with nitrogen and returned to normal pressure to stop the polycondensation reaction. The polycondensation reaction was discharged in cold water in a strand form and immediately cut to obtain polyester pellets.

The pellets were dried and heat-treated, and the decrease in intrinsic viscosity was measured.

Table 1 shows the results.

[0038]

[Table 1]

In the metal complex compounds of Examples 1 and 2 in which the π-coordinate has the most stable structure in the molecular orbital calculation, the metal complex compound of the comparative example in which the σ-coordination is the most stable is different from the metal complex compound of the comparative example in which the σ coordination is the most stable. The tendency that the decrease in viscosity was small was obtained. From this result, the metal complex compound having the π-coordinate state is
It is presumed that the thermal decomposition reaction which is a side reaction of the polyester condensation polymerization reaction is suppressed.

[0040]

Industrial Applicability The metal complex compound of the present invention has an excellent catalytic action on condensation polymerization in the synthesis of polyester, and also has an action of suppressing a thermal decomposition reaction occurring as a side reaction. Therefore, a polymer polymerized by using the catalyst hardly causes a decrease in the heat resistance of the polyester due to thermal decomposition at the time of re-melting, and a small variation in the quality and a decrease in the strength of the molded product. it can.

Continued on the front page F-term (reference) 4J029 AA03 AB04 AC01 AD01 BA02 BA03 BA04 BA05 BA07 BA10 CA02 CA03 CA04 CA06 CB04A CB05A CB06A CB10A CC05A CC06A CD03 CD07 JF071 JF241 JF251 JF461 JF481 JF521 JF03 KB02 KB05 K03 KD05 K03 KD05

Claims (10)

[Claims] 1. A polyester polymerization catalyst, which is a metal complex compound containing an organic ligand, wherein a central metal of the compound is π-coordinated to an ester surface of the polyester. 2. The polyester polymerization catalyst according to claim 1, which is a metal complex compound, wherein the shape of the lowest unoccupied molecular orbital obtained by molecular orbital calculation is p-type or d-type. 3. The method according to claim 1, wherein the central metal in the metal complex compound is In, T
3. The polyester polymerization catalyst according to claim 1, wherein the catalyst is at least one selected from the group consisting of 1, As, Bi, Se, Te, Fe and Cu. 4. The catalyst for polyester polymerization according to claim 1, which is a metal complex compound and has an organic ligand which coordinates to a central metal. 5. A metal complex compound, wherein the organic ligand coordinated to the central metal contains an oxygen atom, and at least two or more oxygen atoms are present relative to the central metal according to claim 3 or 4. The polyester polymerization catalyst according to any one of claims 1 to 4, wherein the catalyst is bonded. 6. The polyester raw material according to claim 1, wherein
A method for producing a polyester, comprising performing a polymerization reaction by adding any one of the polyester polymerization catalysts. 7. The method for producing a polyester according to claim 6, wherein the polyester has a structural unit derived from an aromatic dicarboxylic acid. 8. The method according to claim 7, wherein the polyester is polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polyethylene naphthalate or polypropylene naphthalate. 9. The method for producing a polyester according to claim 6, wherein the raw material of the polyester is an aromatic dicarboxylic acid, an ester-forming derivative thereof and a diol, or a low molecular weight polyester oligomer thereof. 10. The process for producing a polyester according to claim 6, wherein the amount of the polymerization catalyst added is 0.2 to 500 ppm in terms of the central metal relative to the obtained polyester.