JPS62174226A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain a modified polyester which can be easily dyed with a basic dye and is good in productivity, by polycondensing an ester of an aromatic dicarboxylic acid with a glycol in the presence of a phosphorus compound and a specified polycondensation catalyst. CONSTITUTION:A phosphorus compound and a polycondensation catalyst are added to an ester of an aromatic dicarboxylic acid and/or its esterifiable deriva tive with a glycol and/or an oligomer of the ester, and the mixture is polycondensed to obtain the purpose polyester. As said polycondensation catalyst, a product obtained by heating an antimony compound and hydroxybenzoic acid and/or its derivative in a solvent is used. This process is remarkably effec tive especially when part of the aromatic dicarboxylic acid is a sulfonic acid compound of the formula wherein R1 and R2 are each H or a 1-4C alkyl, M is a metal such as Na, Li, K, Ti, Ca, Zn, Mg or Mn.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing polyester with excellent productivity, and more particularly to a method for producing modified polyester with good productivity that is easily dyed with basic dyes. Regarding the method.

(Prior Art) Polyesters, particularly polyesters containing terephthalic acid as the main acid component, have excellent mechanical, physical, and chemical properties, and are therefore widely used in fibers, films, and other molded products.

Among such polyesters, polyesters whose main glycol component is ethylene glycol, tetramethylene glycol, hexamethylene glycol or cyclohexane-1,4-dimethylol are important.

Such polyesters, for example, polyethylene terephthalate, are generally produced by adding a phosphorus compound as a stabilizer to ethylene glycol ester of terephthalic acid and/or its low polymer, and then heating under reduced pressure to cause a polycondensation reaction. There is. The polyester thus obtained is usually extruded in a molten state into a fiber or film form through fine holes (spinning holes) or slits, and then stretched for practical use.

In addition, the above polycondensation reaction can be carried out by using a catalyst.
For the first time, the process proceeds smoothly and a commercially valuable polyester can be obtained.The reaction rate and the quality of the resulting polyester are greatly influenced by the type of catalyst used.

Conventionally, antimony compounds such as antimony trioxide have been most widely used as polycondensation catalysts because they have an excellent polycondensation reaction promotion effect and can yield polyesters with relatively good color tone. . Such a polycondensation catalyst is usually added to the polyester manufacturing process separately from the phosphorus compound used as a stabilizer.

However, the polyester obtained in this way is
It has the disadvantage of poor melt moldability, especially poor spinnability. That is, when a polyester obtained by separately adding an antimony compound as a polycondensation catalyst and a phosphorus compound as a stabilizer is melt-spun, a bending phenomenon (hereinafter referred to as During spinning and drawing, yarn breakage occurs frequently, and eventually spinning itself becomes impossible. Therefore, when bending occurs, it becomes necessary to interrupt spinning and replace the spinneret, which significantly impedes production.

In order to overcome this drawback, in order to improve the release properties of the polymer stream from the spinneret surface, we have investigated mold release agents such as silicone, examined the material of the spinneret, examined the shape of the spinning hole, and added additives. Various measures are being considered, including consideration of However, none of these effects were sufficient.

In order to resolve the above-mentioned drawbacks, the present inventors have conducted extensive studies on bending during melt spinning of polyester, and have found that foreign matter that adheres and accumulates around the outside of the spinning hole after the start of spinning (hereinafter referred to as spindle surface foreign matter) and bending. I learned that there is a close relationship between the two, and that by suppressing the accumulation of foreign matter on the mouthpiece surface, it is possible to prevent pending. Furthermore, upon analysis of such foreign matter on the spindle surface, it was found that the main component was the antimony component used as a polycondensation catalyst, and that the antimony compound in the polymer sublimated during spinning to become foreign matter on the spindle surface.

Based on these findings, the inventors of the present invention filed a patent application No. 58-176305 in order to reduce the sublimation of antimony compounds during spinning.
In the specification of this issue, we proposed a method for producing polyester in which an antimony compound and a phosphorus compound as a stabilizer, which are conventionally added separately, are heated in glycol and the resulting product is used as a polycondensation catalyst. .

As originally intended, the polyester obtained by this manufacturing method does not cause bending due to less foreign matter adhering to the spinneret surface (it can be spun more stably for a longer period of time than when conventional polyester is used).

(Problems to be Solved by the Invention) As described above, polyester obtained by using a heat-treated product of an antimony compound and a phosphorus compound as a polycondensation catalyst is
The performance in the molding process can be improved compared to the conventional method because the amount of antimony compounds that sublimate during melt molding is reduced, but in order to further improve the performance of the molding process, it is necessary to further reduce the amount of foreign matter adhering to the mouth surface. need to be reduced.

In addition, since polyester fibers have insufficient dyeability, efforts were made to improve the dyeability of polyester fibers, for example,
As seen in Publication No. 10497, a method of copolymerizing polyester with a metal sulfonate group-containing compound to improve dyeability with basic dyes has been carried out. In particular, the performance in the molding process was not sufficient, and further measures to reduce the amount of foreign matter adhering to the mouth surface were desired.

Furthermore, polyester obtained by using a heat-treated product of an antimony compound and a phosphorus compound as a polycondensation catalyst tends to have insoluble foreign matter in the polymer, and the rate of increase in pack pressure during molding, especially during melt spinning, is higher than that of an antimony compound. and a phosphorus compound separately.

For this reason, if the spinning pack pressure becomes too high, spinning problems such as an increase in yarn breakage and/or an increase in drawing breakage and fuzz will occur.
Problems occur such as deterioration of the drawing process condition, deterioration of process passability in higher-order processing steps, or deterioration of the quality of the final product, which requires replacing the spinning pack in a short period of time, which significantly reduces productivity. let This tendency is particularly remarkable in copolyesters containing metal sulfonate compounds.

As described above, the polyester obtained by the conventional polyester manufacturing method has not been able to fully satisfy the productivity of the molding process and subsequent processes.

An object of the present invention is to provide a method for producing polyester that can reduce the adhesion of foreign matter to the spinneret surface and suppress an increase in spinning pack pressure.

(Means for Solving the Problems) The present inventors have found that in order to achieve the above object (as a result of studies), a treated product obtained by heat-treating an antimony compound and p-oxybenzoic acid in ethylene glycol in advance. The present invention was achieved based on the discovery that polyester used as a polycondensation catalyst has an extremely small amount of foreign matter adhering to the spinneret surface and a small increase in spinning pack pressure.

That is, the present invention adds a phosphorus compound and a polycondensation catalyst to an aromatic dicarboxylic acid and/or its ethylene-forming derivative, a glycol ester and/or its low polymer,
Then, in producing a polyester through a polycondensation reaction, a treated product obtained by preheating an antimony compound and oxybenzoic acid and/or a derivative thereof in a solvent is used as the polycondensation catalyst. This is a method for producing polyester.

As the difunctional carboxylic acid used in the production method of the present invention, terephthalic acid is mainly used, and as its ester-forming derivative, lower alkyl esters having 1 to 4 carbon atoms, phenyl esters, etc. are preferably used. ´Reru. In addition, a part of this terephthalic acid component (usually 20 mol%
(below) may be replaced by other difunctional carboxylic acids or ester-forming derivatives thereof. Examples of other difunctional carboxylic acids include isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenylsulfodicarboxylic acid, diphenylmethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, and β-hydroxyethoxybenzoic acid. Examples include difunctional aromatic carboxylic acids, sebacic acid, adipic acid, and difunctional aliphatic carboxylic acids such as oxalic acid.

Moreover, the method of the present invention can produce particularly remarkable effects when a part of the aromatic dicarboxylic acid is a sulfonic acid compound represented by the following general formula (1).

Preferred compounds represented by the above general formula (1) include 5-sodium sulfoisophthalate dimethyl ester, 5-lithium sulfoisophthalate dimethyl ester, 5-potassium sulfoisophthalate dimethyl ester, and 5-sodium sulfoisophthalate dimethyl ester. (p-hydroxythyl) ester, 5-lithium sulfoisophthalate bis(p-hydroxyethyl) ester, and the like.

Among these, 5-sodium sulfoisophthalic acid dimethyl ester is preferred.

The compound containing such a metal sulfonate group is preferably copolymerized with 0.5 to 10 mol%, particularly preferably 1.0 to 6.0 mol% of the aromatic carboxylic acid and/or its ester-forming derivative. It is mole%.

If the metal sulfonate group is less than 0.5 mol%, the resulting polyester tends to have insufficient affinity for basic dyes, and if it exceeds 10 mol%, not only will the excellent properties unique to polyester be impaired. , the manufacturing cost of the polyester increases.

In addition, the timing of addition of the metal sulfonate group-containing compound is 5.
- In the case of lower alkyl esters such as sodium sulfoisophthalate dimethyl ester, before the start of the transesterification reaction, and in the case of bisglycol esters such as 5-sodium sulfoisophthalate bis(hydroxyethyl) ester, before the transesterification reaction. It is preferable to carry out the reaction after the start of the transesterification reaction, or after the start of the transesterification reaction and before the end of the transesterification reaction, or before the end of the esterification reaction.

As the glycol, ethylene glycol is mainly used, and as its ester-forming derivative, ethylene oxide is particularly preferably used. In addition, aliphatic glycols such as triethylene glycol, tetramethylene glycol, hexamethylene glycol, and cyclohexane-1,4-dimethylol may be used, and two or more types of these glycols may be used.

A specific method for producing a glycol ester and/or a low polymer thereof from such an acid component and a glycol component includes, for example, producing an ethylene glycol ester of terephthalic acid and/or a low polymer thereof used for producing polyethylene terephthalate. To explain this, generally adopted methods include direct esterification reaction of terephthalic acid and ethylene glycol, transesterification reaction of lower alkyl ester of terephthalic acid and ethylene glycol, or reaction of terephthalic acid and ester oxide. There is. Further, any catalyst can be used in these reactions as necessary.

In addition, there is no need to adopt special conditions for the polycondensation reaction employed in the production method of the present invention, and glycol esters of difunctional carboxylic acids and/or their low polymers are subjected to a polycondensation reaction to form polyesters. The conditions adopted when doing so are arbitrarily adopted.

In the production method of the present invention, it is important to use a treated product obtained by previously heat-treating an antimony compound and an oxybenzoic acid compound and/or its derivative in a solvent as a polycondensation catalyst.

Here, even if a polyester obtained by adding an antimony compound and oxybenzoic acid and/or its derivatives separately without heat treatment is subjected to melt spinning, the amount of foreign matter adhering to the mouth surface cannot be sufficiently reduced. Can not.

Any antimony compound can be used as long as it has polycondensation catalytic ability. Generally, oxides such as antimony trioxide, antimony tetroxide, and antimony pentoxide, halides such as antimony trichloride and antimony tribromide, alcoholades such as antimony glycolate, etc. are preferred, and oxides are particularly preferred. .

Moreover, as the oxybenzoic acid to be heat-treated in a solvent with an antimony compound, p-oxybenzoic acid and m-oxybenzoic acid are preferable, and p-oxybenzoic acid is particularly preferable.

Further, as the derivative of oxybenzoic acid, an alkyl ester (having 1 to 4 carbon atoms) of oxybenzoic acid or an acetoxy compound is preferable, and p-acetoxybenzoic acid is particularly preferable.

Such a heat treatment of an antimony compound and oxybenzoic acid is carried out by heating the antimony compound and oxybenzoic acid at 50 to 200°C in an appropriate solvent and adding
It is preferable to hold the temperature for 5 minutes to 5 hours, and the solvent used at this time is preferably a glycol used in the production of the target polyester, particularly ethylene glycol.

The product obtained by heat-treating such an antimony compound and oxybenzoic acid and/or its derivatives may be used as it is dissolved in a solvent, or may be used after isolation. Even after purification, it may be used after being redissolved in a suitable solvent, such as glycol.

In the present invention, a treated product obtained by heat-treating the antimony compound and oxybenzoic acid and/or its derivative is added as a polycondensation catalyst to perform a polycondensation reaction. The ratio of the amounts of the antimony compound and oxybenzoic acid and/or its derivatives to be added at this time must simultaneously satisfy the following formulas (II) and (I[) in relation to the phosphorus compound used as a stabilizer. preferable.

1.0≦P/S≦50 (If) 0.
5≦A/P≦20 (I[I) Here, when P/S is less than 1.0, the phosphorus compound is too small, and foreign matter on the spinneret surface due to antimony occurs during spinning of the obtained polyester. On the other hand, if P/S exceeds 50, the amount of phosphorus compounds becomes too large, and foreign matter tends to be produced in the polyester. Furthermore, when A/P is less than 0.5, the amount of oxybenzoic acid and/or its derivatives is too small, and it is difficult to sufficiently suppress the increase in spinning pack pressure during spinning of the obtained polyester (on the contrary, A/P If it exceeds 20, the progress of the polycondensation reaction may be delayed or the physical properties of the resulting polyester may be impaired.

The amount of the antimony compound added at this time is suitably 0.01 to 0.1 mol % based on terephthalic acid and/or its ester-forming derivative, which is a raw material for polyester.

In the present invention, during the heat treatment, part or all of the metal phosphide added as a stabilizer in the polyester manufacturing process is added to the ester compound and oxybenzoic acid and/or its derivatives, and then heat-treated. The resulting treated product may be used as a polycondensation catalyst.

Even in polyester obtained using such a polycondensation catalyst,
The generation of foreign matter on the spinneret surface during spinning can be suppressed, and an increase in spinning pack pressure can be sufficiently suppressed.

As such a phosphorus compound, a compound represented by the following general formula (IV) is preferable.

(O)7 RIO-P-OR,... (■).

duck OR.

Here, the -valent organic group specifically refers to an alkyl group,
Aryl group, aralkyl group or ((CHz) 0)
t=Ra (However, R4 is a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, l is an integer of 2 or more, and k is an integer of 1 or more), etc., and R, R, and R are the same or different. However, among them, an alkyl group, a hydroxyalkyl group, or a phenyl group is preferable.

Preferred specific examples of such phosphorus compounds include phosphoric acid, phosphorous acid, di- or trimethyl phosphate, mono-, di- or triethyl phosphate, mono-, di- or triphenyl phosphate, mono-, di- or triphenyl phosphite, mono-, di- or tri-β-hydroxyethyl phosphate, mono-, di- or tripolyoxyethylene (5 moles of EO added) lauryl ether phosphate (however, EO5
Molar addition means addition of 5 moles of ethylene oxide (hereinafter the same meaning), mono-, di-, tripolyoxyethylene (addition of 8050 moles) methyl ether phosphate alone or in mixtures, etc. However, particularly preferred examples include trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tri-β-hydroxyethyl phosphate alone or in mixtures.

In addition, it is not necessary to adopt special conditions for the polycondensation reaction in the present invention, and a glycol ester of terephthalic acid and/or its derivative and glycol and/or its low polymer are subjected to a polycondensation reaction to form a polyester. The conditions adopted at that time will be arbitrarily adopted.

Furthermore, in carrying out the present invention, other polycondensation catalysts may be used in combination without departing from the purpose of the present invention, and optional additives such as colorants, matting agents, and fluorescent materials may be added as necessary. Optical brighteners, stabilizers, ultraviolet absorbers, ether bond inhibitors, dye-facilitating agents, flame retardants, antistatic agents, and the like may be used.

(Function) In the method for producing polyester of the present invention, a heat-treated product obtained by heat-treating an antimony compound and oxybenzoic acid in a solvent in advance is used as a polycondensation catalyst.
# With polyester, the antimony compound contained in the polymer can be converted into a non-sublimable one, and the amount of insoluble foreign matter can be extremely reduced.As a result, even when such fi polyester is subjected to melt spinning, there is no foreign matter that adheres and accumulates around the outside of the spinning hole. Since the amount of the yarn is extremely low, spinning can be carried out stably for a long period of time without bending of the discharged yarn, and since the increase in spinning pad and vine pressure is low, the pack replacement cycle can be significantly extended. Furthermore, the process conditions after the spinning process can be significantly improved.

(Example) Next, the present invention will be described in detail with reference to Examples. In the examples, parts are parts by weight, and [η] is the intrinsic viscosity determined from the value measured at 30° C. in orthochlorophenol solvent. The L value and b value representing color tone are values measured using a Hunter type color difference meter, and the higher the (L-b) value, the better the color tone.

Example 1 (a) Heat treatment of antimony compound and oxybenzoic acid 2 parts of ethylene glycol, 0.05 part of antimony dioxide, and 0.2 parts of p-oxybenzoic acid were charged into a reaction tank equipped with a stirrer, and the mixture was heated at 190°C under normal pressure reflux. Heat treatment was performed at ℃ for 2 hours.

(b) Production of polyester 100 parts of dimethyl terephthalate, 7 parts of ethylene glycol
0 parts and 0.02 manganese acetate as transesterification catalyst
heating the two-part mixture from 150°C to 240°C;
It took 4 hours to carry out the transesterification reaction while distilling off methanol.

Here, trimethyl phosphate 0.20 as a stabilizer
Add the entire amount of the reaction product obtained in step (a) above.
/S = 8.3, A/P = 10.01) Then, after adding an ethylene glycol slurry containing 0.3 parts of titanium dioxide as a matting agent, the temperature was raised from 250°C to 290°C to a temperature of 1 wHg or less. A polycondensation reaction was carried out under reduced pressure for 4 hours to obtain polyethylene terephthalate having [η) of 0.636, a softening point of 261.9°C, a color tone value of 68.5, and a b value of 4.5.

The spinning property evaluation of this polyethylene terephthalate is 40
A spinning pack with a filtration area of 32c+J and 0.3m using mesh, 60 mesh, and 200g of seven random sand.
Using a spinneret with mφ and 30 holes, the output amount is 80 g.
/win, spinning temperature 285℃, take-up speed 1200m/
The undrawn yarn obtained as described above was spun at 85° C. for 7 days, and the changes in the spinning pack pressure, the height of foreign matter around the outside of the spinning hole, and the occurrence of bending were investigated. Stretching ratio: 3.5 times, stretching speed: 1100 m/Tsuru, 150 denier/30 filament: 2.5
This was done by investigating the wrap rate when the weight was changed to kg@.

As a result, no bending was observed during the 7-day spinning period, and the pack pressure increased by an average of 0.5 kg/Cl/l/
The spinnability was extremely good, and the height of the foreign matter on the spinneret surface after 7 days was only 5 μm.

Furthermore, the lapping ratio during stretching was 0.15%, and the stretchability was also extremely good.

Comparative Example 1 In Example 1, antimony dioxide and p-oxybenzoic acid were not heat-treated in advance (in addition to being added separately after the phosphorus compound was added in the polyester manufacturing process of Example 1-(b)). Polyester was produced in the same manner as in Example 1, and its spinnability was evaluated.

The obtained polyethylene terephthalate has [η) 0.
64, softening point 262.0℃, color tone value 67.9, b value 5
．． It was 1.

In addition, during the 7-day spinning period of this polymer, bending occurred from the 4th day after the start of spinning, and the height of foreign particles on the spinneret surface after 7 days was as high as 40μ, and the wrap rate during stretching was poor at 5%. Ta.

In addition, the pack pressure increase during spinning of such polymer is 2 kg/
cj/day.

Example 2 Except for using p-acetoxybenzoic acid instead of p-oxybenzoic acid used in Example 1-(a),
A heat-treated product was prepared in the same manner as in Example 1-(a), and polyester was produced in the same manner as in Example 1-(b), except that the obtained heat-treated product was used as a polycondensation catalyst. The spinning property was evaluated by the method of Example 1. The obtained polymer had a [η) of 0.64, a softening point of 262.0°C, and a color tone of L.
The value was 67.5, b(i4.6).This polymer was
No bending was observed during the 7-day spinning period.
The increase in pack pressure was small at an average of 0.3 kg/c+a/day, the spinnability was extremely good, and the height of foreign matter on the spinneret surface after 7 days was only 10 μm. Also, the ramp rate during stretching is 0
．． It was as low as 2%, and the stretchability was also extremely good.

In this case, P/S=8.3 and A/P=0.8.

Examples 3 to 6 Example 1-(a) except that phosphoric acid was used instead of trimethyl phosphate in Example 1-(a), and the amounts of phosphoric acid and p-oxybenzoic acid used were varied as shown in Table 1. A polyester was produced in the same manner as in Example 1-(b), except that the reaction product was prepared in the same manner as in a), and the obtained reaction product was used. Siluminability was evaluated by the method described in Example 1.

The results were as shown in Table 1.

(This page, blank space below) Example 7 In Example 1-(a), 0.05 part of phosphoric acid was added, and 0.05 part of antimony trioxide and 0.05 part of p-oxybenzoic acid were added.
Polyester was produced and its spinnability was evaluated in the same manner as in Example 1, except that 2 parts were heat-treated in ethylene glycol.

In this case, P/S=3.0 and A/P=2.8.

The polyethylene terephthalate thus obtained was [
η) 0.64, softening point 261.8°C, color tone value 67°3, and b value 4.4.

Additionally, no bending was observed during the 7-day spinning period for this polymer, and the pack pressure increased by an average of 0.5 kg/
The spinnability was as small as cTA/day, and the spinnability was extremely good, and the height of the foreign matter on the spinneret surface after 7 days was only 8 μm. Furthermore,
The wrap ratio during stretching was also as low as 0.2%, and the spinning properties were extremely good.

Example 8 86 parts of terephthalic acid and 39 parts of ethylene glycol were charged into a pressure-resistant autoclave, and 3 kg/co!
The mixture was heated from 220° C. to 260° C. under pressure of G, and an esterification reaction was carried out while water was distilled off over a period of 3 hours.

Here, trimethyl phosphate 0.20 as a stabilizer
After adding the entire amount of the heat-treated product obtained in exactly the same manner as in Example 7, and further adding an ethylene glycol slurry containing 0.3 parts of titanium dioxide as a matting agent, the mixture was heated from 250°C to 29°C.
The temperature was raised to 0°C and the polycondensation reaction was carried out for 4 hours under reduced pressure of 1+uHg or less [η) 0.64, softening point 261.7°C,
Polyethylene terephthalate with a color tone value of 69.0 and a b value of 4.2 was obtained.

No bending was observed during the 7-day spinning period of this polymer, and the pack pressure increased by an average of 0.5 kg/crA.
It was as small as 7 days, and the spinnability was extremely good, and the height of the foreign matter on the spinneret surface after 7 days was only 5 μm. Furthermore, the wrap ratio during stretching was as low as 0.14%, and the spinning properties were extremely good.

Comparative Example 2 Prepared in the same manner as Example 7 except that phosphoric acid and antimony trioxide were heat-treated in advance without using p-oxybenzoic acid used in Example 7, and the resulting heat-treated product was polycondensed. Polyester was produced and its spinnability was evaluated in the same manner as in Example 7, except that it was used as a catalyst. [η] of the obtained polymer was 0.64, and the softening point was 262.1.
℃, and the color tone was L value 67.2 and b value 4.5. No bending was observed during the 7-day spinning period of this polymer, and the height of the foreign matter on the mouth surface after 7 days was only 5μ, which was good, but the pack pressure increased by an average of 5kg/cJ/
The spinnability was significantly poor.

Example 9 100 parts of dimethyl terephthalate, 7 parts of ethylene glycol
A mixture consisting of 0 parts, 4 parts of dimethyl 5-sodium sulfoisophthalate, and 0.032 parts of manganese acetate, 0605 parts of lithium acetate, and 0.019 parts of cobalt acetate as a transesterification catalyst was heated from 150°C to 240°C for 4 hours. The transesterification reaction was carried out while distilling methanol out.

Here, trimethyl phosphate 0.20 as a stabilizer
P/S = 8.3, A/P = 10.1), and further contained 0.3 parts of titanium dioxide as a matting agent. Ethylene glycol slurry was added. After that, heat the indoor bath at 220℃ for 10 minutes.
After reacting for 28 minutes under reduced pressure of less than 1 am Hg.
Heating at 5°C for 4 hours to cause polycondensation reaction, [η) 0
．． A modified polyester having a softening point of 4B, a softening point of 256.8°C, a color tone value of 69°2, and a b value of 6.2 was obtained.

The spinning properties of this polymer were evaluated using 40 mesh, 60 mesh, and 200 g of seven random sand, a spinning bank with a filtration area of 32 mm, and a 0.10 mφ, 24-hole spinneret, at a spinning temperature of 300°C. Pick up speed 12
This was carried out by spinning at 00 m/min for 7 days, and then drawing the obtained undrawn yarn.

As a result, the spinning pack pressure increase of the polymer over 7 days was as small as 2.2 kg/cni/day on average, and no bending was observed during the 7-day spinning period, and the spinnability was extremely good. In addition, the height of foreign matter on the mouthpiece surface after 7 days was 10μ.
The ramp ratio during stretching was only 0.2%, and the stretchability was also good.

Comparative Example 3 Example 9 was repeated except that antimony dioxide and p-oxybenzoic acid were not heat-treated in advance and were added separately after the phosphorus compound was added in the polyester manufacturing process of Example 9. Polyester was produced in the same manner.

The quality of the obtained modified polyester was [η]0°48,
The softening point was 256.7°C, the color tone value was 67.6, and the b value was 6.5.

Furthermore, when the spinning properties of this polymer were evaluated using the method described in Example 9, bending occurred from the third day after the start of spinning, and spinning became impossible on the fourth day, and the average spinning puncture pressure increased over the four days. It was large at 8.0 kg/cflrZ day.

Example 10 Except for using p-acetoxybenzoic acid instead of p-oxybenzoic acid used in Example 1-(a),
A heat-treated product was prepared in the same manner as in Example 1-(a), and polyester was produced in the same manner as in Example 9, except that the obtained heat-treated product was used as a polycondensation catalyst, and the spinning properties were evaluated. did. [η] of the obtained polymer is 0.48, softening point is 256.9°C, color tone is L value 69.1, b value 4.8
Met. No bending was observed during the 7-day spinning period of this polymer, and the pack pressure increased by an average of 2.1 kg.
/cj/day, the spinnability was extremely good, and the height of the foreign matter on the spinneret surface after 7 days was only 11μ. Furthermore, the lapping ratio during stretching was as low as 0.2%, and the stretchability was also extremely good.

In this case, P/S=8.3 and A/P=0.8.

Examples 11 to 14 Example 1-(a) except that phosphoric acid was used instead of trimethyl phosphate in Example 1-(a), and the amounts of phosphoric acid and p-oxybenzoic acid used were varied as shown in Table 2. (
A polyester was produced in the same manner as in Example 9, except that the reaction product was prepared in the same manner as in (a) and the obtained reaction product was used.

The quality and spinnability evaluation results of the obtained polyester were evaluated in the second
Shown in the table.

Example 15 In Example 1-(a), 0.05 part of phosphoric acid was added, and 0.05 part of antimony dioxide and 0.05 part of p-oxybenzoic acid were added.
Polyester was produced and its spinnability was evaluated in the same manner as in Example 9, except that 2 parts were heat-treated in ethylene glycol.

In this case, P/S = 3.0, A/P = 2.8
Met.

The polyethylene terephthalate obtained in this way is (
η) 0.48, softening point is 257.0℃, color tone is L value 6
The b value was 8.8 and the b value was 5.2.

Additionally, no bending was observed during the 7-day spinning period for this polymer, and the pack pressure increased by an average of 2.3 kg/
The spinnability was as small as cTA/day, and the spinnability was extremely good, and the height of the foreign matter on the spinneret surface after 7 days was only 9 μm. Furthermore,
The wrap ratio during stretching was also as low as 0.2%, and the spinning properties were extremely good.

Example 16 86 parts of terephthalic acid, 40 parts of ethylene glycol, 5-
A mixture consisting of 4 parts of dimethyl sodium sulfoisophthalate, 0.05 part of lithium acetate, and 0.019 parts of cobalt acetate was charged into a pressure-resistant autoclave, and the amount was 3 kg/cd.
The mixture was heated from 220° C. to 260° C. under pressure of G, and an esterification reaction was carried out while water was distilled off over a period of 3 hours.

Here, the stabilizer and 0.20 part of trimethyl phosphate,
After adding the entire amount of the heat-treated product obtained in exactly the same manner as in Example 7 to obtain an ethylene glycol slurry containing 0.3 parts of titanium dioxide as a matting agent, the temperature was raised from 240°C to 285°C to 1 mmHg or less. A polycondensation reaction was carried out for 4 hours under a reduced pressure of 0.48, a softening point of 257.0° C., a color tone value of 69.8, and a b value of 5.0 to obtain polyethylene terephthalate.

No bending was observed during the 7-day spinning period of this polymer, and the average pack pressure increase was 1.9 kg/cal.
/ day, the spinnability was extremely good, and the height of the foreign matter on the spinneret surface after 7 days was only 9 μm. In addition, the wrap ratio during stretching was as low as 0.2%, and the spinning properties were extremely good.

Comparative Example 4 Prepared in the same manner as in Example 15, except that phosphoric acid and antimony dioxide were heat-treated in advance without using the p-oxybenzoic acid used in Example 15, and the resulting heat-treated product was subjected to polycondensation. Polyester was produced and its spinnability was evaluated in the same manner as in Example 15, except that it was used as a catalyst. The obtained polymer has a [η) of 0.4B and a softening point of 25
The temperature was 6.9°C, the color tone value was 69.0, and the b value was 5.1. No bending was observed during the 7-day spinning period for this polymer, and the height of the foreign matter on the mouth surface after 7 days was only 5μ, which was good, but the pack pressure increased by an average of 20 kg/
The spinnability was very poor at aA/day.

(Effect of the invention) With the polyester obtained by the production method of the present invention,
Not only can productivity, which has been a problem in the past, be improved, but the quality of the final product can also be improved, making it easier to pass the process in higher-order processing, and the effects are extremely large.

Claims (1)

[Claims] 1. A phosphorus compound and a polycondensation catalyst are added to an ester of an aromatic dicarboxylic acid and/or its ester-forming derivative and a glycol and/or a low polymer thereof, and then a polycondensation reaction is carried out. A method for producing polyester, which comprises using, as the polycondensation catalyst, a treated product obtained by previously heat-treating an antimony compound and oxybenzoic acid and/or its derivatives in a solvent. 2. A part of the aromatic dicarboxylic acid has the following general formula (I)
Claim 1, which is a sulfonic acid compound represented by
Method for producing polyester as described in Section 1. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) In the formula, R_1 and R_2 are hydrogen atoms or carbon atoms with 1 to 1 carbon atoms.
4 alkyl group, M is Na, Li, K, Ti, Ca,
Indicates metal atoms of Zn, Mg, and Mn. 3. The method for producing polyester according to claim 1 or 2, wherein the antimony compound is an oxide. 4. The method for producing polyester according to claim 1, 2 or 3, wherein the oxybenzoic acid is p-oxybenzoic acid. 5. The method for producing polyester according to claim 1, 2 or 3, wherein the oxybenzoic acid derivative is p-acetoxybenzoic acid. 6. The method for producing polyester according to claim 1, 2 or 3, wherein the solvent is ethylene glycol. 7. The method for producing polyester according to claim 1 or 2, wherein the added amounts of the phosphorus compound, antimony compound, and oxybenzoic acid satisfy the following formulas (II) and (III) at the same time. 1.0≦P/S≦50 (II) 0.5≦A/P≦20 (III) [S is the number of moles of the antimony compound, P is the number of moles of the antimony compound The number of moles, A, indicates the number of moles of oxybenzoic acid and/or its derivative. ] 8. Claims 1, 2, 3, and 7 in which the phosphorus compound is a compound represented by the following general formula (IV)
A method for producing polyester according to any one of the items. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (IV) [In the formula, R_1, R_2 and R_3 are hydrogen atoms or monovalent organic groups, and R_1, R_2 and R_3 are
They may be the same or different. n is an integer of 0 or 1. ]