JPH1149852A - Method for producing polyester excellent in moldability and polyester polymerization catalyst used therefor - Google Patents

Abstract

(57) [Problem] A method for producing a polyester having excellent moldability and eliminating problems such as stains on a die, an increase in filtration pressure, and thread breakage in the production of molded articles for fibers, films, bottles and the like. And a polyester polymerization catalyst used for the same. A method for producing a polyester by polycondensing a product obtained by an esterification reaction or a transesterification reaction with an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof, A method for producing a polyester, comprising using an aluminum compound as a condensation catalyst and adding an alkali, and a polyester polymerization catalyst used therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester having excellent moldability and a polyester polymerization catalyst used therein. More specifically, the present invention relates to a method for producing a polyester having excellent moldability and a polymer color tone, and a polyester polymerization catalyst used therein.

[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 hole of the die. If the deposition progresses, it causes a defect in the filament, so that it is necessary to remove the filament in a timely manner. Deposition of antimony catalyst residue occurs because antimony is present in the polymer in the form of antimony glycolate, which is metamorphosed near the base and partially vaporized and dissipated.
It is thought that the component mainly composed of antimony remains in the base.

Further, antimony catalyst residue in the polymer tends to be relatively large particles, and becomes a foreign matter, 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.

In order to solve such a problem, for example, USP
In 5,512,340 and USP 5,596,069,
It has been proposed to use an aluminum compound such as aluminum chloride or aluminum hydroxide chloride in combination with a cobalt compound. However, in general, aluminum compounds are difficult to dissolve in the reaction system of glycol or polyester such as ethylene glycol, and when added directly to the reaction system of polyester as a polycondensation catalyst, insoluble foreign matter is formed. It breaks, and in the end, the problem of antimony cannot be fully avoided.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polyester comprising an aluminum compound and an alkali compound, which has solved the above-mentioned drawbacks of the polyester containing an antimony compound, and a polyester polymerization catalyst used therefor. Is what you do.

[0009]

An object of the present invention is to provide a product obtained by an esterification reaction or an ester exchange reaction with an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. In the method of producing a polyester by polycondensation, using an aluminum compound as a polycondensation catalyst,
It is achieved by a method for producing a polyester, characterized by adding an alkali 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 the most widely used polyethylene terephthalate or a polyester copolymer mainly composed of polyethylene terephthalate.

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 aluminum compound in the present invention is not particularly limited. Specifically, aluminum hydroxide, aluminum chloride, inorganic aluminum compounds such as aluminum hydroxide chloride, aluminum acetate, aluminum benzoate, aluminum lactate, aluminum laurate,
Carboxylates such as aluminum stearate, aluminum ethylate, aluminum isopropylate, aluminum tri-n-butylate, aluminum tri-s
ec-butyrate, aluminum tri-tert-butylate, mono-sec-butoxyaluminum diisopropylate, etc., aluminum alcoholate, ethyl acetoacetate aluminum diisopropylate, which is a compound having a structure in which the hydrogen of the hydroxyl group of an alcohol is replaced with an aluminum element Aluminum tris (ethyl acetoacetate), alkyl acetoacetate aluminum diisopropylate, aluminum monoacetyl acetate bis (ethyl acetoacetate), aluminum tris (acetyl acetate), aluminum monoisopropoxy monooleoxy ethyl acetoacetate, aluminum acetylacetonate, etc. Part or all of the alkoxy groups of the aluminum alcoholate Aluminum chelate is a compound substituted with a chelating agent such as Chiruaseton like.

Among them, aluminum hydroxide, aluminum chloride, aluminum hydroxide chloride and aluminum acetate, which are relatively inexpensive, have a low molecular weight and a high content ratio of aluminum atoms, are preferably used.

Further, the use of aluminum hydroxide or aluminum acetate is particularly preferable because it does not contain a halogen because the resulting polymer has better heat resistance and color tone. Incidentally, the aluminum acetate of the present invention may be a so-called basic aluminum acetate which is generally commercially available.

The aluminum compound of the present invention is preferably added in an amount of 5 to 500 ppm by weight with respect to the polyester compound obtained in terms of aluminum atoms. If the amount added is less than 5 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 likely to be generated, and the increase in filtration pressure during molding may be remarkable, or the color tone of the polymer may be deteriorated. More preferably, 10 to 200 ppm, further preferably, 1
0 to 100 ppm.

The alkali compound of the present invention is an alkali compound in a broad sense.
As shown in Iwanami Shoten, 1982), it refers to the entire group consisting of hydroxides of alkali metals and alkaline earth metals, as well as alkali metal carbonates, ammonia, amines and derivatives thereof.

The amount of the alkali compound of the present invention is 50 to 5000 ppm based on the obtained polyester composition.
It is preferred that If it is less than 50 ppm, it is difficult to obtain the effect of suppressing the formation of foreign substances, and if it exceeds 5000 ppm, the color tone of the obtained polyester composition may be deteriorated. As an addition amount, 70 to 300
0 ppm is more preferable, particularly preferably 80 to 100 ppm.
It is 0 ppm.

In the present invention, it is preferable to use a nitrogen-containing compound among these alkali compounds, since the resulting polyester composition has particularly good color tone.

Preferred nitrogen-containing compounds of the present invention include, for example, compounds represented by the following formulas 1 and 2.

[0021]

(Equation 1)

[0022]

(Equation 2) More specifically, the compound of the formula 1 includes ammonia, diethylamine, trimethylamine, triethylamine, tripropylamine, tributylamine and the like. Examples of the compound of the formula 2 include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylbenzylammonium hydroxide and the like.

Further, as a compound other than Formula 1 or 2,
Derivatives of the compound of Formula 1 or Formula 2, ethylenediamine, tetraethylenediamine, hexamethylenediamine, pyridine, quinoline, pyrroline, pyrrolidone, piperidine, and the like may be used.

As the nitrogen-containing compound of the present invention, among the above-mentioned compounds, a tertiary amine compound or a quaternary ammonium compound is preferable because foreign matters are less particularly generated in the obtained polyester. More preferably, 280 ° C
When the compound volatilizes at the following temperature, the residual amount in the finally obtained polyester decreases, and the color tone of the polyester is further improved, which is preferable. Examples of such compounds include tertiary amine compounds such as trimethylamine, triethylamine, tripropylamine, and tributylamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and trimethylamine hydroxide. And quaternary ammonium compounds such as benzylammonium.

The amount of the nitrogen-containing compound of the present invention is 10 to 1000 in terms of nitrogen atoms based on the obtained polyester.
It is preferably ppm. In order to sufficiently obtain the effect of suppressing the formation of foreign substances and to improve the color tone of the obtained polyester, the addition amount is more preferably from 30 to 800 ppm, particularly preferably from 50 to 500 ppm.

The aluminum compound of the present invention may be added as it is to the polyester reaction system. However, the aluminum compound may be added to water containing an alkali compound, an organic solvent or a mixture of water and an organic solvent, and then added to the reaction system. This is preferable because the formation of foreign substances in the polyester of the aluminum compound is further suppressed. In particular, it is preferable to mix an aluminum compound with the aqueous solution after mixing the alkali compound with water to form an aqueous solution, since the aluminum compound is uniformly dispersed or dissolved in the aqueous solution, and the generation of foreign substances in the polyester is further suppressed. It is also preferable to dilute the aqueous solution containing the aluminum compound with a diol component forming a polyester such as ethylene glycol and then add it to the reaction system, since local concentration or the like due to a rapid temperature change hardly occurs.

When the aluminum compound is previously mixed with water, an organic solvent or a mixture of water and an organic solvent containing an alkali compound in advance, the alkali compound is mixed with water, the organic solvent or the mixture of water and the organic solvent. When the concentration is 0.5 to 50% by weight, more preferably 1 to 40% by weight, the aluminum compound to be added later is preferably dispersed or dissolved more easily.

As the solution to be added to the polyester reaction system, the aluminum compound is 0.05 to 20% by weight in terms of aluminum atom, and the alkali compound is 0.05 to 20% by weight.
When the concentration is from 30% by weight to 30% by weight, foreign matters in the obtained polyester composition are particularly small, which is preferable. When the alkali compound is a nitrogen-containing compound, it is 0.05% in terms of nitrogen atoms.
When the concentration is from 20 to 20% by weight, the amount of foreign substances in the obtained polyester is particularly small, which is preferable.

In the present invention, it is preferable to use a cobalt compound in combination with the above-mentioned aluminum compound because the polycondensation reaction proceeds more rapidly and the color tone of the obtained polyester is further improved.

The cobalt compound of the present invention is not particularly limited, but specific examples include cobalt acetate tetrahydrate, cobalt nitrate, cobalt chloride, cobalt acetylacetonate, cobalt naphthenate and the like.

The addition amount of the cobalt compound is 0.5 in a molar ratio of aluminum atoms to cobalt atoms (Al / Co).
It is preferably set to 20. When the molar ratio is in the range,
The effect of improving the polymerization activity is high, the effect of improving the color tone of the polymer is large, and the heat resistance can be maintained well. It is more preferably 1 to 15, and further preferably 2 to 10.

In the polyester production method of the present invention, an antimony compound may be used in combination. However, if the addition amount of antimony atoms is 50 ppm or less relative to the polymer, yarn breakage during fiber spinning or film production may occur. Breakage during film formation is suppressed, and transparency is favorable in bottles and the like, which is preferable. It is more preferably at most 30 ppm, further preferably at most 10 ppm.

The method for producing the polyester of the present invention will be described with reference to polyethylene terephthalate.

The high molecular weight polyethylene terephthalate used for fibers, films and the like is usually produced by any of the following processes. That is, (1) a process of obtaining low molecular weight polyethylene terephthalate or oligomer by direct esterification reaction using terephthalic acid and ethylene glycol as raw materials, and further obtaining a high molecular weight polymer by subsequent polycondensation reaction, (2) dimethyl terephthalate (DMT) ) And ethylene glycol as raw materials, a low molecular weight product is obtained by a transesterification reaction, and a high molecular weight polymer is obtained by a subsequent polycondensation reaction.
Here, the esterification proceeds without a catalyst, but the transesterification reaction usually proceeds using a compound such as manganese, calcium, magnesium, zinc, lithium, or the like as a catalyst. After completion, in order to inactivate the catalyst used in the reaction,
Adding a phosphorus compound is performed.

The production method of the present invention comprises the steps (1) and (2)
To the low polymer obtained in the early or early part of the series of reactions,
The specific aluminum compound and the alkali of the present invention are added, and thereafter, the polycondensation reaction in the latter half is advanced to obtain high molecular weight polyethylene terephthalate.

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.

[0037]

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 polymer Measured at 25 ° C. using orthochlorophenol as a solvent.

(2) Metal Content in Polymer Determined by X-ray fluorescence.

(3) Color tone of polymer 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).

(4) Carboxyl end group content of the polymer The method of Maurice et al. [Anal. Chim. Act
a, 22, p363 (1960)].

(5) Strength and Elongation of Fiber Using a Tensilon tensile tester manufactured by Toyo Baldwin Co., Ltd., an SS curve was obtained at a test length of 250 mm and a tensile speed of 300 mm / min to calculate the strength and elongation.

Example 1 20 wt% of tetraethylammonium hydroxide was previously prepared.
10 parts of aluminum hydroxide was added to 100 parts of water containing 100% and stirred to obtain a uniform aqueous solution. The aqueous solution was further diluted with 90 parts of ethylene glycol to prepare a uniform ethylene glycol solution containing tetraethylammonium hydroxide, water and aluminum hydroxide.

On the other hand, a catalyst-free oligomer prepared from high-purity terephthalic acid and ethylene glycol according to a conventional method was melted at 250 ° C., and the above-prepared tetraethylammonium hydroxide, water and aluminum hydroxide were added to the melt. Is added so that the content of aluminum atoms in the finally obtained polyester composition becomes 50 ppm, and further, cobalt acetate tetrahydrate is added so that the content of cobalt atoms becomes 20 ppm. Was added. 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 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, discharged into cold water in a strand form, and immediately cut to obtain polyester pellets.

The intrinsic viscosity of the obtained polymer was 0.68, the amount of carboxyl end groups was 29 equivalents / ton, and the color tone of the polymer was L = 59, a = 0.6 and b = 5.0. Analysis by fluorescent X-ray revealed that the content of aluminum atomic components was 50 pp.
m.

Thus, pellets of the polyester composition having good polymerization reactivity and polymer characteristics 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 there was almost no yarn breakage during stretching, and the polymer had good moldability.

Examples 2 to 11, Comparative Examples 1 to 3 Polymers were polymerized and melt-spun in the same manner as in Example 1 except that the kind and amount of the metal compound or alkali were changed. The results are shown in Tables 1 and 2.

Although those in the claims of the present invention showed good transitions in both the polymer physical properties and the melt spinning process, those polymerized without using an alkali compound and those polymerized with antimony trioxide alone were used in the melt spinning process. In this case, the increase in filtration pressure became noticeable, and many yarn breaks occurred, resulting in poor moldability.

Incidentally, in the spinning properties, filtration pressure and thread breakage are caused by various factors, and foreign matters in the polymer are also one of the main causes. In the examples, those having no or almost no increase in the filtration pressure in the spinning process were regarded as good. In Examples 6 and 7, a slight increase in the filtration pressure was observed, but it did not affect the normal filter filter replacement cycle, and was judged to be within the allowable range. As for the thread breakage, those in which no or almost no thread breakage occurred in the examples were evaluated as good. In Examples 6 and 7, the variation was at the upper limit of the variation of the good level, and was judged to be within the allowable range from the viewpoint of operability.

[0052]

[Table 1]

[Table 2]

[0053]

EFFECT OF THE INVENTION The polyester obtained by the method for producing polyester and the polyester polymerization catalyst of the present invention has excellent moldability and is suitable for producing molded articles such as fibers, films, bottles, etc. Problems such as cuts are eliminated.

Claims (14)

[Claims] 1. A process for producing a polyester by polycondensing a product obtained by an esterification reaction or a transesterification reaction with an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof, A method for producing a polyester, comprising using an aluminum compound as a polycondensation catalyst and adding an alkali compound. 2. An amount of an aluminum compound of 5 to 500 ppm in terms of aluminum atom based on the obtained polyester.
The method for producing a polyester according to claim 1, wherein the polyester is added. 3. The method according to claim 1, wherein an alkali compound is added to the obtained polyester in an amount of 50 to 5000 ppm. 4. The method according to claim 1, wherein the aluminum compound is at least one compound selected from the group consisting of hydroxides, chlorides, hydroxide chlorides and acetates of aluminum. A method for producing the polyester according to claim 1. 5. The method for producing a polyester according to claim 1, wherein the alkali compound is a nitrogen-containing compound. 6. The method according to claim 5, wherein the nitrogen-containing compound is a tertiary amine compound or a quaternary ammonium compound.
The method for producing a polyester composition according to the above item. 7. The process for producing a polyester according to claim 1, wherein the aluminum compound is previously mixed with water or an organic solvent containing an alkali compound and then added as the mixture. . 8. The method for producing a polyester according to claim 1, wherein the antimony compound is added in the polyester production step so as to be 50 ppm or less as an antimony atom based on the polyester. 9. The method according to claim 1, wherein the cobalt compound is added in the polyester production step such that the molar ratio of aluminum atoms to cobalt atoms is 0.5 to 20 (Al / Co). A method for producing a polyester according to any one of the preceding claims. 10. The method for producing a polyester according to claim 1, wherein the polyester is a polymer mainly composed of polyethylene terephthalate. 11. The method for producing a polyester according to claim 1, wherein the polyester is used for fiber application. 12. A polyester polymerization catalyst comprising a solution containing an aluminum compound and an alkali compound, wherein the medium comprises water, an organic solvent or a mixture of water and an organic solvent. 13. An aluminum compound in an amount of 0.05 to 20% by weight in terms of aluminum atom, and an alkali compound in an amount of 0.5 to 20% by weight.
The polyester polymerization catalyst according to claim 12, which is contained in an amount of from 30 to 30% by weight, respectively. 14. The process for producing a polyester polymerization catalyst according to claim 12, wherein the aqueous solution containing an alkali compound or an organic solvent or a mixture of water and an organic solvent is prepared in advance, and then an aluminum compound is added.