JP2002080574A - Method for producing polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyester having slight antimony content and having good color tone and heat resistance. SOLUTION: In this method for producing the polyester by polycondensing a product obtained by esterification reaction or transesterification of an aromatic dicarboxylic acid or its ester-formed derivative with a diol or its ester- formed derivative, a titanium compound and a phosphorus compound are mixed with the diol or the ester-formed derivative thereof and the mixture is heated at 160-220 deg.C and is added to the reaction system to attain the production of the polyester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a polyester.

[0002]

2. Description of the Related Art Due to its excellent properties, polyesters are widely used in various fields including 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 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, polyesters having a low or no antimony content have been demanded.

[0007] When a role of the polycondensation catalyst is required for compounds other than the antimony compound from such a background, titanium compounds and germanium compounds are known, and the use of relatively inexpensive and highly active titanium compounds is studied. However, this compound has a problem that the color tone and heat resistance of the polymer are reduced.

As a method for improving the color tone and heat resistance of such a titanium compound, for example, a method using a composite oxide composed of titanium and silicon as a catalyst is described in WO95 / 18839, and Japanese Patent Application Laid-Open No. 54-101896. Although a method of adding a cobalt compound and an alkali metal compound has been proposed, there has been a problem that the effect of improving color tone and heat resistance is still insufficient while maintaining sufficient catalytic activity.

[0009]

An object of the present invention is to provide a method for producing a polyester having a low antimony content and having good color tone and heat resistance.

[0010]

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 which a titanium compound and a phosphorus compound are mixed with a diol or an ester-forming derivative thereof, heated to 160 to 220 ° C., and then added to the reaction system.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester of the present invention is a polymer synthesized from dicarboxylic acid or its ester-forming derivative and diol or its ester-forming derivative, and can be used as molded articles such as fibers, films, bottles, and the like. There is no particular limitation as long as it is possible.

Specific examples of such polyester 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, in addition to diethylene glycol, copolymerizable components such as adipic acid, isophthalic acid, sebacic acid, phthalic acid, dicarboxylic acids such as 4,4'-diphenyldicarboxylic acid, and ester-forming derivatives thereof, and polyethylene. Dioxy compounds such as glycol, hexamethylene glycol, neopentyl glycol, and polypropylene glycol, oxycarboxylic acids such as p- (β-oxyethoxy) benzoic acid, and ester-forming derivatives thereof may be copolymerized.

In the present invention, it is necessary to mix a titanium compound and a phosphorus compound with a diol or an ester-forming derivative thereof, heat the mixture to 160 to 220 ° C., and then add the mixture to the reaction system. When the heating temperature is lower than 160 ° C., the effect of improving the color tone and heat resistance of the obtained polyester is small. It is preferably 180 from the viewpoint of the color tone and heat resistance of the polyester.
To 220 ° C, more preferably 190 to 220 ° C.

In the present invention, the molar ratio (Ti / P) of titanium atoms to phosphorus atoms contained in a mixture of a titanium compound, a phosphorus compound and a diol or an ester-forming derivative thereof is preferably from 0.1 to 10. When the molar ratio is less than 0.1, it is difficult to obtain a sufficient polymerization activity. When the molar ratio is larger than 10, the effect of improving color tone and heat resistance is reduced. From the viewpoint of polymerization reactivity, color tone and heat resistance, the molar ratio of titanium atom to phosphorus atom is more preferably 0.1 to 5.

The mixture of the titanium compound, the phosphorus compound and the diol or its ester-forming derivative is preferably added in the form of a solution. If there is a precipitate in the mixture, the precipitate is likely to become a foreign substance in the polymer, which may cause an increase in the filter pressure of the filter during molding, breakage of the yarn during spinning, or breakage of the film during film formation.

The concentration of the titanium compound in the mixture is 0.01
It is preferably from 10 to 10% by weight. Particularly preferably, it is 0.1 to 2.0% by weight. When the concentration of the titanium compound is less than 0.01% by weight, the added amount of the diol or the ester-forming derivative thereof is increased, and the resulting polyester such as a by-product of the diol dimer and a decrease in the softening point is reduced. Physical properties may be reduced. On the other hand, when the concentration of the titanium compound exceeds 10% by weight, the composite oxide is hardly dissolved in the reaction system, and it is difficult to obtain a sufficient effect of suppressing foreign substances.

The titanium compound in the present invention is used in an amount of 0.5 to 150 pp in terms of Ti atom with respect to the obtained polyester.
Addition of m is preferable because the polymerization activity is high and the color tone and heat resistance of the obtained polymer are good. More preferably 1
To 100 ppm, more preferably 3 to 50 ppm.

As the titanium compound, specifically, titanium alkoxides such as titanium butoxide and titanium tetraisopropoxide, titanium complexes, titanium oxide and the like can be used. In addition, a composite oxide in which the main metal element is titanium and silicon can be used as the titanium compound.

Examples of the titanium complex include titanium compounds containing a chelating agent such as ethylenediaminetetraacetic acid, hydroxyethyliminodiacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, or a mixture thereof, but are not particularly limited. It is not something to be done.

In the case of titanium oxide, the molecular weight is 100,000.
(G / mol) is preferable in terms of catalytic activity and foreign matter suppression. The molecular weight of the titanium oxide is more preferably 500
~ 100,000 (g / mol), more preferably 100
0 to 50,000 (g / mol), particularly preferably 150
0 to 20000 (g / mol).

The method for producing titanium oxide and a composite oxide in which the main metal element is composed of titanium and silicon is not particularly limited. For example, in a method of producing a titanium alkoxide compound as a raw material by a hydrolysis reaction, Is obtained by controlling the speed. 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.

The phosphorus compound in the present invention has a molecular weight of 50 to 500 (g / mo) from the viewpoint of polymerization activity and heat resistance.
1) is preferred. More preferably 100 to 2
50 (g / mol), more preferably 130 to 230
(G / mol).

Specific examples of the phosphorus compound include phosphoric acid, phosphorous acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, di-2-ethylhexyl phosphate, triphenyl phosphate, phenylphosphonic acid, diethylphosphonoacetic acid, Examples thereof include methyl diethylphosphonoacetate and ethyl diethylphosphonoacetate.

Further, it is preferable to use a compound in which the phosphorus compound is selected from the group consisting of compounds having a structure represented by the general formula (1), since heat resistance is particularly improved.

[0026]

Embedded image (R1, R2: hydrogen atom or hydrocarbon group; R3: oxygen, acid aliphatic or aromatic hydrocarbon group; X: hydrogen, carboxyl group, or hydrocarbon group.) In the method for producing the polyester of the present invention, An antimony compound may be used in combination. However, when the addition amount of the antimony atom is 50 ppm or less, breakage of the fiber at the time of spinning of the fiber or breakage of the film at the time of film formation is suppressed, and transparency in a bottle or the like is preferably improved. It is more preferably at most 30 ppm, further preferably at most 10 ppm. Particularly preferably, it is substantially not contained.

The present invention will be described using polyethylene terephthalate as an example.

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 and ethylene In this process, a low molecular weight product is obtained by transesterification using glycol as a raw material, and then 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
For the purpose of inactivating the catalyst used in the reaction, a phosphorus compound is added.

The production method of the present invention comprises the steps (1) and (2)
To the low polymer obtained at any stage of the series of reactions, preferably in the first half of the series of reactions (1) or (2), a titanium compound mixed with the present invention and heated to 160 to 220 ° C., phosphorus A mixture of the compound and ethylene glycol is added to the reaction system, and thereafter, the second-stage polycondensation reaction proceeds to obtain a high-molecular-weight polyethylene glycol.

The above 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 the systems.

[0031]

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) Titanium and phosphorus contents in the polymer were 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) Amount of carboxyl terminal group of polymer Maurice et al. [Anal. Chim. Act
a, 22, p363 (1960)]. (5) DEG amount of polymer After decomposing with monoethanolamine and acetylating, the amount of DEG in the extract was measured by gas chromatography. (6) Heat resistance of polyester After polyester pellets are dried in advance at 150 ° C. under a reduced pressure of 133 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,
Immersed and held in a silicone oil bath heated to a temperature. The polymer was sampled at the time when the entire contents were dissolved and 8 hours after that, and the respective intrinsic viscosities [η] 0,
When [η] was 1, the value represented by the following equation 1 was used as an index of heat resistance.

(Heat resistance index) = {[η] 0− [η] 1} / [η] 0 (formula 1) A heat resistance index of less than 0.60 is a first class, 0.60 or more and 0.
Less than 63 was defined as secondary, and 0.63 or more as tertiary. Primary and secondary polymers are preferable since they do not cause a decrease in the degree of polymerization during molding.

Example 1 A mixed solution 10 of titanium isopropylate and ethyl orthosilicate having a composition of Ti / Si = 90/10 (molar ratio)
Then, 10 parts of 2-methylpentane-2,4-diol and 2 parts of ethanol were added to the mixture, and the mixture was stirred at 60 to 70 ° C. for 3 hours, and 3 parts of ethanol containing 2 parts of water was slowly added dropwise. Heated to ° C. to get a clear gel. The gel was further left at the same temperature for 15 hours, and then dried under reduced pressure at 130 ° C. using a rotary evaporator to obtain a gel. Further, the dry gel and trimethyl phosphate were added to ethylene glycol at a titanium compound concentration of 0.3% by weight,
/P=1.0 (molar ratio) at 200 ° C.
, And then cooled to 100 ° C in 60 minutes.
A composite oxide of titanium / silicon having a composition of i = 90/10 (molar ratio) and trimethyl phosphate are converted to Ti atom / P
A clear ethylene glycol solution containing atoms = 1.0 (molar ratio) was prepared.

On the other hand, a catalyst-free oligomer produced from high-purity terephthalic acid and ethylene glycol by a conventional method is melted at 250 ° C., and the above-prepared titanium / silicon composite oxide and trimethyl phosphate are added to the melt. Was added so that the content of titanium atoms in the finally obtained polyester was 10 ppm. 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. The polycondensation reaction was discharged in 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 40 minutes.

The intrinsic viscosity of the obtained polymer is 0.66,
Carboxyl end group amount 11 equivalents / ton, DEG amount 0.9%, polymer color tone L = 65, a = -0.7,
b = 7.0 and the heat resistance index was 0.597. In addition, analysis by fluorescent X-ray confirmed that the content of the titanium atom component was 10 ppm and the content of the phosphorus atom component was 6 ppm.

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.

Examples 2 to 4 Molar ratio of Ti atom / P atom, Ti compound concentration,
A polymer was polymerized in the same manner as in Example 1 except that the heating temperature was changed, and melt spinning was performed.

Example 5 A polymer was polymerized and melt-spun in the same manner as in Example 1 except that the phosphorus compound was changed to trimethyl diethylphosphonoacetate.

Example 6 Titanium tetraisopropylate and 1,6-hexanediol were used in 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. Further, the ethanol solution and trimethyl phosphate were converted to ethylene glycol with a titanium oxide concentration of 0.3.
% By weight, Ti / P = 1.0 (molar ratio), heated at 200 ° C., cooled to 100 ° C. in 60 minutes, and added titanium oxide and trimethyl phosphate having a molecular weight of 5000 g / mol. A transparent ethylene glycol solution containing Ti atoms / P atoms = 1.0 (molar ratio) was prepared. A polymer was polymerized and melt-spun in the same manner as in Example 1 except for using the adjusted liquid.

Example 7 Titanium nitrilotriacetic acid and trimethyl phosphate were added to ethylene glycol so that the concentration of titanium nitrilotriacetic acid was 0.3% by weight and Ti / P = 1.0 (molar ratio). After heating at 100 ° C., the mixture was cooled to 100 ° C. in 60 minutes, and titanium nitrilotriacetic acid and trimethyl phosphate were dissolved in T
A transparent ethylene glycol solution containing i atoms / P atoms = 1.0 (molar ratio) was prepared. A polymer was polymerized and melt-spun in the same manner as in Example 1 except for using the adjusted liquid.

Example 8 A polymer was polymerized and melt-spun in the same manner as in Example 1 except that the Ti atom content in the polymer was changed to 56 ppm.

Comparative Example 1 A polymer was polymerized and melt-spun in the same manner as in Example 1 except that an adjusting solution containing no phosphorus compound was used.

Comparative Example 2 A polymer was polymerized and melt-spun in the same manner as in Example 1 except that an adjusting solution containing no phosphorus compound was used and trimethyl phosphate was added during polymerization.

Comparative Example 3 Example 1 was repeated except that the heating temperature of the adjustment liquid was changed to 130 ° C.
The polymer was polymerized in the same manner as described above, and melt spinning was performed.

Comparative Example 4 A polymer was polymerized in the same manner as in Example 1 except that antimony trioxide and trimethyl phosphate were used as a catalyst, and melt spinning was performed.

The results of Examples 1 to 8 and Comparative Examples 1 to 4 are shown in Tables 1 and 2. Those falling within the scope of the present invention exhibited good transitions in polymer physical properties and yarn-making properties, but those falling outside the claims of the present invention exhibited poor color tone and heat resistance. In the case of using antimony trioxide, the heat resistance and the color tone changed favorably, but the spinneret was stained during spinning and the yarn was frequently broken.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

The polyester obtained by the process for producing a polyester according to the present invention is excellent in molding processability. In the production of molded products for fibers, films, bottles, etc., the degree of polymerization decreases due to thermal degradation, and stains on the base are reduced. The problem is solved.

 ──────────────────────────────────────────────────の Continued on front page F term (reference) 4J029 AA03 AB04 AE01 AE02 AE03 BA02 BA03 BA05 BA10 BD03A BD04A BF25 CA02 CA06 CB04A CB06A CB10A CC05A CC06A EB06A HA00 HA01 HB00 HB01 JC571 JF321 KB05 KE02 KE03

Claims (10)

[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, Mixing a titanium compound and a phosphorus compound with a diol or an ester-forming derivative thereof,
A method for producing a polyester, which comprises adding the mixture to a reaction system after heating to 20 ° C. 2. A molar ratio (Ti / P) of titanium atoms to phosphorus atoms contained in a mixture of a titanium compound, a phosphorus compound and a diol or an ester-forming derivative thereof is from 0.1 to 10. A method for producing the polyester according to claim 1. 3. A reaction system comprising a mixture of a titanium compound, a phosphorus compound and a diol or an ester-forming derivative thereof in a solution state.
Or the method for producing a polyester according to 2. 4. The method according to claim 1, wherein the concentration of the titanium compound in the mixture is 0.01
The method for producing a polyester according to claim 1, 2 or 3, wherein the amount is 10 to 10% by weight. 5. The polyester as claimed in claim 1, wherein the titanium compound is added to the obtained polyester in an amount of 0.5 to 150 ppm in terms of titanium atoms. Method. 6. The method for producing a polyester according to claim 1, wherein the titanium compound is a composite oxide containing titanium and silicon as main metal elements. 7. The method according to claim 1, wherein the titanium compound is a titanium complex. 8. A titanium compound having a molecular weight of 100,000 (g / g).
(mol) or less titanium oxide, the method for producing polyester according to any one of claims 1 to 5. 9. The phosphorous compound having a molecular weight of 50 to 500 (g / m
ol), characterized in that:
The method for producing a polyester according to the above item. 10. The method for producing a polyester according to claim 9, wherein the phosphorus compound is a compound represented by the formula (1). Embedded image (R1, R2: hydrogen atom or hydrocarbon group. R3: oxygen, aliphatic or aromatic hydrocarbon group. X: hydrogen, carboxyl group or hydrocarbon group.)