JP2001200045A - Catalyst for manufacturing polyester and method for manufacturing polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a catalyst for manufacturing a polyester excellent in processability and heat resistance and resolved in problems such as head stain, filter pressure rise and thread breakage, and to provide a method for manufacturing the polyester. SOLUTION: The catalyst for manufacturing a polyester comprises titanium oxide as a main component and a titanium compound having a molecular weight of 500-100,000 g/mol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for producing polyester which gives a polyester having excellent moldability and heat resistance, and a method for producing polyester using the same.

[0002]

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

[0003] Polyethylene terephthalate is generally produced from terephthalic acid or its ester-forming derivative and ethylene glycol. In commercial processes for producing high molecular weight polymers, antimony compounds are widely used as polycondensation catalysts. . However, polymers containing antimony compounds have some undesirable properties, as described below.

[0004] For example, it is known that when polyester obtained by using an antimony catalyst is melt-spun into fibers, residues of the antimony catalyst accumulate around the die hole. If the deposition progresses, it causes a defect in the filament, so that it is necessary to remove the filament in a timely manner. It is believed that the accumulation of antimony catalyst residue occurs because the antimony compound in the polymer is denatured in the vicinity of the base, a part of which evaporates and dissipates, and then components mainly composed of antimony remain in the base. .

[0005] Antimony catalyst residue in the polymer tends to be relatively large particles, and becomes a foreign substance, which causes an increase in the filter pressure of the filter during molding, breakage of yarn during spinning, or breakage of film during film formation. Has undesirable characteristics such as

[0006] In view of the above background, there is a demand for polyesters having an extremely low or no antimony content.

As a polycondensation catalyst other than the antimony compound, a titanium compound such as alkoxytitanium is generally known as a highly active compound. Recently, for example, WO95 / 18839 and the like have also proposed a special titanium compound in which the main metal element is titanium and silicon. However, simply using such a titanium-based catalyst composition solves the above-mentioned problems caused by the antimony catalyst, but lowers the heat resistance of the polymer and reduces the operability during molding and processing of the polymer. However, there is a problem that another problem that the temperature decreases.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the titanium compound catalyst in the production of polyester and to provide a polyester composition having excellent moldability and heat resistance. is there.

[0009]

SUMMARY OF THE INVENTION An object of the present invention described above is to provide a titanium oxide as a main component and a molecular weight of 500 to 500.
It is achieved by a polyester production catalyst characterized by being a titanium compound of 100,000 (g / mol) and a polyester production method using the compound.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION 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, and may be used as a molded article such as a fiber, a film or a bottle. There is no particular limitation as long as it is possible.

Specific examples of such polyesters include, for example, polyethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene 2,6-naphthalenedicarboxylate, and polyethylene-1,2-bis ( 2
-Chlorophenoxy) ethane-4,4'-dicarboxylate, polypropylene terephthalate and the like. The present invention is suitable for polyethylene terephthalate or a polyester copolymer based on ethylene terephthalate, which is most widely used.

These polyesters include, as copolymerization components, dicarboxylic acids such as adipic acid, isophthalic acid, sebacic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, and ester-forming derivatives thereof, polyethylene glycol, diethylene glycol. And dioxy compounds such as hexamethylene glycol, neopentyl glycol and polypropylene glycol; oxycarboxylic acids such as p- (β-oxyethoxy) benzoic acid; and ester-forming derivatives thereof.

The titanium compound of the present invention is mainly composed of titanium oxide and has a molecular weight of 500 to 100,000 (g / g).
mol) of a titanium compound. That is, unlike a conventionally known titanium-based polyester production catalyst such as tetrabutyl titanate, it is not a monomolecular titanium compound having one titanium atom in one molecule,
It is necessary that a molecule having a certain size functions as one catalyst. By having such a form, a high degree of heat resistance of the polyester, which cannot be achieved by a conventional monomolecular titanium compound, can be obtained. The reason for this is not clear, but it is presumed that the catalytic activity becomes mild and the activity against the decomposition of polyester is suppressed by the catalyst having a certain size. On the other hand, if the molecular weight of the titanium compound is too large, the catalytic activity is greatly reduced, and foreign substances are easily generated, which is not preferable. The molecular weight of the titanium compound of the present invention is from 1,000 to
50,000 (g / mol) is more preferable, and
20,000 (g / mol) is more preferable, and 2000
Particularly preferred is from 10,000 to 10,000 (g / mol).

It is preferable that the titanium compound of the present invention is added in an amount of 0.5 to 300 ppm with respect to the polyester in terms of titanium atom, from the viewpoint of the heat resistance of the obtained polyester, and more preferably 2 to 300 ppm. 200pp
m, more preferably 3 to 100 ppm, particularly preferably 3 to 50 ppm.

The method for producing the titanium compound of the present invention is not particularly limited. For example, it can be obtained by controlling the rate of hydrolysis in a method of producing a titanium alkoxide compound as a raw material by a hydrolysis reaction. Specifically, for example, a small amount of another metal alkoxide compound such as silicon or zirconium or a polyhydric alcohol compound is allowed to coexist with a titanium alkoxide compound as a main raw material, and a coprecipitation method, a partial hydrolysis method, It can be synthesized by a chemical sol-gel method or the like. Here, the coprecipitation method is a method in which a solution having a predetermined composition containing two or more types of components is prepared, and the hydrolysis reaction proceeds with the composition. The partial hydrolysis method is a method in which one component is previously hydrolyzed, the other component is added thereto, and the hydrolysis is further advanced. The coordination chemical sol-gel method is a method in which a titanium alkoxide raw material and a polyhydric alcohol compound having a plurality of functional groups in the molecule coexist, and a reaction product is formed between the two in advance, so that the subsequent hydrolysis is performed. It is intended to control the speed of the reaction. Methods for synthesizing the above compounds are described in, for example, Ueno et al., "Preparation of Catalyst Using Metal Alkoxide", IPC (1993), and the like.

Examples of the titanium alkoxide used for producing the above compound include titanium isopropylate,
Titanium ethylate or titanium-tert-butylate is exemplified. Examples of the solvent for performing the reaction include methanol, ethanol, propanol, and isopropanol.

Here, a synthesis method in which a polyhydric alcohol compound coexists is preferred because the hydrolysis rate is relatively easy to control. Examples of the polyhydric alcohol compound used include ethylene glycol, 1,2-propanediol,
1,2-butanediol, 1,3-propanediol,
1,3-butanediol, 2,4-pentadiol1,
4-butanediol, 1,5-pentanediol, 1,
Examples thereof include diols such as 6-hexanediol and trivalent or higher alcohols such as glycerol, propanetriol, hexanetriol, trimethylolpropane, pentaerythritol and sorbitol. Diols are preferred in view of the stability of the titanium compound, and diols having 5 or more carbon atoms are particularly preferred.

Further, with respect to the titanium oxide obtained by this production method, the molar ratio of the polyhydric alcohol to the titanium atom (polyhydric alcohol / titanium) is 0.1 to 1%.
When the polyhydric alcohol compound is contained so as to be 0, the heat resistance of the obtained polyester is good, which is preferable.
More preferably, the molar ratio (polyhydric alcohol / titanium) is 0.5-5, particularly preferably 0.7-1.2.

In the use of the catalyst for producing polyester of the present invention, it is preferable to use a phosphorus compound in addition, since the heat resistance of the obtained polymer is further improved. The phosphorus compound is preferably added so that the molar ratio of the phosphorus atom to the titanium atom in the obtained polymer is Ti / P = 0.1 to 20. More preferably, Ti / P
= 0.2 to 10, more preferably Ti / P = 0.3 to
5

Such a phosphorus compound is not particularly limited, and examples thereof include, but are not limited to, phosphoric acid, phosphorous acid, phosphonic acid, and lower alkyl esters and phenyl esters thereof. Specifically, for example, phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, phosphorous acid, trimethyl phosphite, methylphosphonic acid, phenylphosphonic acid, benzylphosphonic acid, methylphosphonic acid methyl ester, phenylphosphonic acid Acid ethyl ester, benzylphosphonic acid phenyl ester,
Ethyl phosphonoacetate and the like.

In the production of the polyester of the present invention,
An alkaline earth metal compound, a cobalt compound or the like may be added together with the titanium compound or the phosphorus compound.

Here, when the total amount of the alkaline earth metal compound and / or the cobalt compound is 5 to 300 ppm based on the polyester in terms of metal atoms, the heat resistance and the color tone of the polymer are good, which is preferable. More preferably 5-150 ppm, even more preferably 10-150 ppm
100 ppm.

Of these, a cobalt compound is preferred because the color tone of the polyester is particularly good. The amount of the cobalt compound to be added is preferably 5 to 250 ppm, more preferably 5 to 120 ppm, and still more preferably 10 to 80 ppm with respect to the polyester obtained in terms of metal atoms. Further, when the molar ratio (Ti / Co) of the titanium compound and the cobalt atom is 0.3 to 20, the heat resistance of the polyester is particularly good, which is preferable.

Such alkaline earth metal compounds and cobalt compounds are not particularly limited. For example, chlorides, acetates, carbonates and the like of each alkaline earth metal,
Examples thereof include cobalt chloride, cobalt nitrate, cobalt carbonate, cobalt acetylacetonate, cobalt naphthenate, and cobalt acetate tetrahydrate.

The polyester produced in the present invention can be used in various conventional processes for the purpose of reducing friction with contact objects such as various guides and rollers in the molding process to improve the processability and to adjust the color of the product. Known particles may be contained.

The type of particles is not particularly limited, and any conventionally known particles can be used. Specifically, for example, silicon dioxide, titanium dioxide, calcium carbonate,
Inorganic particles such as barium sulfate, aluminum oxide, and zirconium oxide, and organic polymer particles such as cross-linked polystyrene can be used. Among these particles, titanium dioxide particles are preferable because of their good dispersibility in the polymer and relatively low cost.

These particles are produced by various wet and dry methods, and if necessary, are subjected to pretreatment such as pulverization and classification, and then added to the polyester reaction system. The addition of the particles to the polyester reaction system may be at any stage before the polycondensation reaction starts, but if added after substantially completing the esterification or transesterification reaction, the dispersibility of the particles in the polymer may be reduced. It is preferable because it becomes good.

The amount of the particles added to the polymer and the particle size vary depending on the application and are not particularly limited, but are 0.001 to 20% by weight based on the polyester composition and 0.05 to 5 μm as the average particle size. Within this range, process passability and color tone are particularly good, which is preferable.

The method for producing the polyester of the present invention will be described by taking polyethylene terephthalate as an example.

The polyethylene terephthalate used for fibers, films and the like is usually produced by any of the following processes. That is, (1) a process of using terephthalic acid and ethylene glycol as raw materials to obtain a low molecular weight substance or oligomer by a direct esterification reaction and further obtaining a high molecular weight polymer by a subsequent polycondensation reaction, and (2) dimethyl terephthalate (DMT). In this process, ethylene glycol is used as a raw material to obtain a low molecular weight substance or oligomer by a transesterification reaction, and then to obtain a high molecular weight polymer by a polycondensation reaction. Here, in general, esterification proceeds without a catalyst, while in transesterification, usually, compounds such as manganese, calcium, magnesium, zinc, and lithium are used as catalysts, and transesterification is performed. After being substantially completed,
For the purpose of inactivating the catalyst used in the reaction, a phosphorus compound is added.

The catalyst for producing polyester of the present invention can be used not only as a polycondensation catalyst but also as a catalyst for an esterification reaction or a transesterification reaction. When used as a catalyst for an esterification reaction or a transesterification reaction, (1)
Alternatively, it is added before the start of the series of reactions in (2). At this time, when continuously acting as a polycondensation catalyst, if necessary, the polyester production catalyst of the present invention may be additionally added at any time before the polycondensation reaction is substantially started. . When the catalyst for producing a polyester of the present invention is mainly used as a polycondensation reaction, it may be added at any time before the polycondensation reaction is substantially started. Further, the phosphorus compound is preferably added at the stage when the reaction in the first half of (1) or (2) is substantially completed or at any later stage.

The catalyst for producing polyester of the present invention may be added to the reaction system as a solid or liquid. For example, when the form at room temperature is originally in a solid state, a conventionally known wet or dry pulverization treatment may be used. And then added in powder form, added as a slurry dispersed in ethylene glycol or the like, or further dissolved in water, an organic solvent or a mixture of both to form a solution, and added to the reaction system. It is preferable because the dispersion in the composition easily proceeds uniformly. In particular, dissolved in water, organic solvents or a mixture of both,
It is preferable that the solution is added to the reaction system after the solution is formed, so that it does not easily become a foreign substance in the polymer.

The above-mentioned reaction is carried out in a batch system, a semi-batch system or a continuous system, but the production method of the present invention can be applied to any of these systems.

[0034]

The present invention will be described in more detail with reference to the following examples. The physical properties in the examples were measured by the methods described below. (1) Intrinsic viscosity [η] of polyester Measured at 25 ° C. using orthochlorophenol as a solvent. (2) Content of titanium, silicon, phosphorus, alkaline earth metal, cobalt, etc. in polyester The content of phosphorus, alkaline earth metal, cobalt is fluorescent X
The contents of other metals including wire, titanium and silicon were determined by ICP (inductively coupled plasma) emission analysis.

When the target polyester composition contains titanium dioxide particles or silicon oxide particles,
In order to confirm the content of the binuclear oxide composed of titanium and silicon, the main metal element that is the catalyst residue of the present invention,
X-ray fluorescence or ICP emission analysis is performed after the following pretreatment to remove the influence of particles. That is, the polyester composition is dissolved in orthochlorophenol, and the particles are settled by a centrifuge. Thereafter, only the supernatant is recovered by a gradient method, and the polymer is reprecipitated by adding acetone, filtered, and washed to obtain a polymer from which particles have been removed. If the viscosity of the polymer solution is high during centrifugation, chloroform may be further added to adjust the viscosity of the polymer solution. Metal analysis is performed on the polymer from which the particles obtained by performing the above pretreatment have been removed. (3) Color tone of polyester composition Hunter values (L, a, b) were measured using a color difference meter (SM Color Computer Model SM-3) manufactured by Suga Test Instruments Co., Ltd.
Value).

As the polymer color tone, the b value is preferably 5 or less, more preferably 4 or less, and particularly preferably 2 or less. (4) Carboxyl end group content of polyester composition The method of Maurice et al. [Anal. Chim. Act
a, 22, p363 (1960)].

The amount of the terminal groups is preferably less than 30 equivalents / ton, more preferably 25 equivalents / ton or less. (5) Heat resistance of polyester composition Pellets of the polyester composition were previously prepared at 150 ° C and 133 ° C.
After drying under reduced pressure of Pa or less for 10 hours, an appropriate amount is charged into a test tube. After purging the inside of this test tube with nitrogen,
Immerse and hold in a silicone oil bath heated to 00 ° C. The polymer was sampled at the time when the entire contents were dissolved and 8 hours after the dissolution, and when the intrinsic viscosities [IV] 0 and [IV] 1 were respectively determined, the value represented by the following equation 1 was used as an index of heat resistance. .

(Heat resistance index) = {[IV] 0- [IV] 1} / [IV] 0 (Formula 1) A heat resistance index of less than 0.55 is a first class, and 0.55 or more.
Less than 60 is second grade, 0.60 or more and less than 0.65 is third grade,
0.65 or more was defined as quaternary. Primary to tertiary polymers are preferable since they do not cause a decrease in the degree of polymerization during molding. (6) Molecular weight of titanium compound The weight average molecular weight in terms of polystyrene obtained by using GPC (gel permeation chromatography) was defined as the molecular weight of the titanium compound. Example 1 Titanium tetraisopropylate and 1,6-hexanediol were mixed at a molar ratio of diol to titanium atom of 1.0.
Mix so that 20 parts of ethanol was added to 10 parts of the mixed solution, and 3 parts of ethanol containing 2 parts of water was slowly dropped into a mixture stirred at 60 to 70 ° C. for 3 hours.
Heating to 90-100 ° C gave a clear gel. The gel was further aged at the same temperature for 15 hours. When the weight average molecular weight of the gel contained in this ethanol solution was measured by GPC, it was 5000 g / mo in terms of polystyrene.
l.

On the other hand, a catalyst-free low polymer produced from high-purity terephthalic acid and ethylene glycol according to a conventional method is melted and stirred at 250 ° C., and a polyester obtained by adding phosphoric acid in terms of phosphorus atoms is added to the melt. 30p for
pm. Thereafter, cobalt acetate tetrahydrate is added so as to have a concentration of 50 ppm in terms of cobalt atoms. Thereafter, the ethanol solution of the titanium compound prepared above is added to the polyester finally obtained so that the content of the titanium compound in the polyester obtained is titanium atom. It was added so as to be 20 ppm in conversion. Thereafter, while stirring the low polymer at 30 rpm, the temperature of the reaction system was gradually raised from 250 ° C. to 285 ° C., and the pressure was reduced to 40 Pa. The time required to reach the final temperature and the final pressure was 70 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, discharged into cold water in a strand form, and immediately cut to obtain polyester pellets.
The time from the start of the pressure reduction to the arrival of the predetermined stirring torque was 2 hours and 50 minutes.

The intrinsic viscosity of the obtained polymer is 0.65,
The carboxyl terminal group amount was 15 equivalents / ton, the color tone of the polymer was L = 60, b = 2.0, and the heat resistance index was 0.51. In addition, ICP emission analysis showed that the content of titanium
It was confirmed that it was 0 ppm. Thus, polyester pellets having good color tone and heat resistance were obtained.

After drying the pellets, the pellets were supplied to an extruder type spinning machine and melt-spun at a spinning temperature of 295 ° C. At this time, a metal nonwoven fabric having an absolute filtration accuracy of 10 μm was used as a filter, and a round hole having a diameter of 0.6 mm was used as a base. 30cm length, 25cm inside diameter
After cooling slowly with a heating cylinder of φ, temperature of 300 ° C, cool and solidify by applying chimney cooling air, refuel, and take off speed 550m
/ Min. This undrawn yarn is drawn at a drawing temperature of 95 ° C while appropriately changing the draw ratio so that the drawn yarn has an elongation of 14 to 15%, and then heat-treated at a heat treatment temperature of 220 ° C and a relaxation rate of 2.0%. Yarn was obtained.

In the melt-spinning step, almost no increase in the filtration pressure during spinning was observed, and the yarn was hardly broken at the time of drawing. Examples 2 to 6 and Comparative Examples 1 to 3 Polymers were polymerized and melt-spun in the same manner as in Example 1 except that the types and amounts of catalyst compounds and the types and amounts of compounds used in combination were changed. The results are shown in Tables 1 and 2.

The polyester of Example 3 is a polymer obtained by adding the titanium compound of the present invention to the direct polymerization method before the start of the esterification reaction and using it as a catalyst during the esterification reaction and the polycondensation reaction.

While the color tone, heat resistance and melt spinning behavior of the present invention were good, those of the present invention were inferior in color tone and heat resistance and markedly increased in filtration pressure in the melt spinning process. Many thread breaks occurred.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

The polyester obtained by using the polyester production catalyst of the present invention is excellent in moldability and heat resistance, and causes stains in a die and an increase in filtration pressure in the production of molded products for fibers, films, bottles and the like. Problems such as thread breakage are eliminated.

Continued on front page F-term (reference) 4J029 AA03 AB04 AB07 AC01 AC02 AE01 AE02 AE03 BA03 BA05 BA08 BD07A CB06A CC06A CG25X HA01 HA02 HB01 HB02 JA091 JA231 JB131 JC481 JC571 JC581 JE241 JF321 KB18

Claims (4)

[Claims] 1. A catalyst for producing a polyester, wherein a main component is titanium oxide and a titanium compound having a molecular weight of 500 to 100,000 (g / mol). 2. A polyhydric alcohol compound in a molar ratio (polyhydric alcohol / titanium) of 0.1 to 10 with respect to titanium atom.
The polyester production catalyst according to claim 1, wherein the catalyst is contained so as to be: 3. A process for producing a polyester, comprising using the catalyst for producing a polyester according to claim 1 or 2, wherein the phosphorus compound relative to the catalyst is 0.1 to 20 as a molar ratio of phosphorus atoms to titanium atoms (Ti / P). A method for producing a polyester, characterized in that it is added so that 4. A method for preparing a polyester production catalyst, comprising:
The method for producing a polyester according to claim 3, wherein the polyester is dissolved in water, an organic solvent or a mixture of both, and then added to the reaction system.