JP2666502B2 - Polyester production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polyester which has improved color tone and stabilizes the color tone, and has reduced black foreign matter. And a method for producing polyester.

[Prior Art] Polyethylene terephthalate or a polyester containing ethylene terephthalate as a main repeating structural unit is extremely valuable in various industrial uses such as for fibers and films.

Such polyesters are used for various industrial uses, and required properties differ depending on the use. Properties commonly required for both film and fiber use include stable color tone, no black foreign matter, and low stains on the spinneret during spinning and film formation. The color tone can be stabilized by stabilizing the temperature conditions in the polycondensation reaction, stabilizing the degree of vacuum and stabilizing the polymerization time. ,
It is in a state where it has to be dealt with by changing under conditions such as vacuum. Since changes in the temperature and vacuum conditions affect other qualities of the obtained polyester, it is difficult to stabilize the color tone by changing the conditions.

In addition, most of the black foreign matter and the stain on the base in the obtained polyester have Sb metal as a main component. Conventionally, various methods have been proposed as a method for reducing such black foreign matter, but in reality, no remarkable improvement effect is observed.

For example, in JP-A-1-185355, a proposal has been made to improve the filtration pressure rise during spinning or film formation by using antimony trioxide with a specified Bi content, and also to improve the color tone of the product. Although this method improves the filtration pressure during spinning and film formation, improves product properties and color tone during spinning and film formation, the effect of the improvement is not stable, and sometimes the polyester yellows, resulting in poor color tone. I was

[Problems to be Solved by the Invention] An object of the present invention is to provide a method for producing polyester, which has a stable color tone, has few black foreign substances, and has a small stain on a spinneret in a process of yarn production and film formation.

[Means for Solving the Problems] An object of the present invention described above is to produce a polyester from an aromatic dicarboxylic acid or a lower alkyl ester thereof and a glycol, and to use a compound of antimony trioxide, bismuth and selenium as a polymerization catalyst. And an antimony trioxide compound having a triethylene glycol (hereinafter referred to as TEG) reducing property of 1.7% or less, a Bi element content of 0.1 ppm to 100 ppm, and a Se element content of 1 ppm to 30 ppm. It can be achieved by a method for producing a polyester characterized by the following.

In order to solve the above-mentioned problems, the inventors of the present application have determined that the contents of the Bi element and the Se element contained in the antimony trioxide-based compound used in the production of polyester and the antimony trioxide-based compound are dissolved by heating in TEG. It has been found that the amount of particles generated when heat treatment is performed for a certain period of time after the formation has a relationship with the color tone stability of polyester and the amount of black foreign matter generated, as well as spinning and stains in a spinneret in a film forming process, and reached the present invention. did.

The evaluation of the TEG reducing property of the antimony trioxide compound in the present invention is performed by the following method.

That is, 5 g of the antimony trioxide compound was added to 250 g of TEG.
, And dissolved under stirring at 250 ° C to 270 ° C for 2 hours, and then filtered through a filter paper (5B type) before cooling. After filtration, the residue is washed with 100 ml of 6N HCl, further washed with 100 ml of ethyl alcohol, and dried. The weight of the filtered product is weighed and expressed as a percentage by weight with respect to the used antimony trioxide-based compound, which is defined as TEG reducibility.

In the present invention, the TEG reducing property is 1.7% or less, preferably 1.5% or less.
% Or less, particularly preferably 1.3% or less, and the Bi element content is less than 100 ppm, preferably less than 70 ppm, particularly preferably less than 50 ppm, and the Se element content is less than 30 ppm.
Below, 5 ppm or more, preferably 20 ppm or less, using an antimony trioxide compound catalyst of 10 ppm or more, TEG reducibility is 1.7
%, The produced polyester has a yellow tint, which is not preferable.

Even if the reducibility of TEG is 1.7% or less, the content of Bi
If it exceeds 100 ppm, the color tone becomes dark, and the generation of black foreign matters increases, which is not preferable. On the other hand, if it is less than 0.1 ppm, the color tone becomes yellowish, which is not preferable. Further, the content of Bi is 1 to 50.
ppm is not preferred. If the content of the Se element exceeds 30 ppm or less than 1 ppm, the color tone becomes yellowish, which is not preferable.

That is, since the antimony trioxide-based compound, which simultaneously satisfies the three requirements of the reducibility of TEG, the content of the Bi element, and the content of the Se element, can be used as the catalyst, the polyester intended for the present invention can be produced. is there.

The antimony trioxide-based compound of the present invention is an ore containing a metal such as antimony element, Bi element and Se element alone or in the form of a compound, heated, melted and evaporated by a general production method to form a mixed gas. Alternatively, a large amount of oxygen or the like is oxidized and then oxidized, and then quenched to precipitate fine particles containing a specific amount of Bi element and Se element containing antimony trioxide as a main component. It is manufactured by adding and mixing an element-containing compound, heating, melting, and evaporating a mixed gas obtained by oxidation.

Bi in the antimony trioxide-based compound obtained by the above process
The contents of the element and the Se element and the TEG reducibility are measured, and an antimony trioxide-based compound within the range specified in the present invention is selected.

As a method for producing the polyester of the present invention, a conventionally known method can be employed.

For example, a method of subjecting a lower alkyl ester of terephthalic acid such as dimethyl terephthalate to a transesterification reaction with ethylene glycol as a raw material, followed by polycondensation, or a method of terephthalic acid (hereinafter referred to as TPA) and ethylene glycol (hereinafter referred to as EG) Any method of polycondensation after the esterification reaction as a raw material may be applied. The method for producing the polyester may be a batch method, a continuous method, or a semi-continuous method using a partially continuous method.

The antimony trioxide-based compound is added before the start of the polycondensation reaction, but may be added to the reaction system before the start of the transesterification reaction or the esterification reaction.

The method of adding the antimony trioxide-based compound may be any of a powder, a slurry of (EG), and a solution dissolved in (EG), and is not particularly limited.

The polyester produced according to the present invention is preferably a polyester produced from an aromatic carboxylic acid or a lower alkyl ester thereof and a glycol, but is preferably isophthalic acid,
Polyester to which a dibasic acid such as phthalic acid or diethylene glycol or a polyhydric alcohol has been added or copolymerized may be used. Depending on the purpose, inert particles such as calcium carbonate, silica and titanium oxide may be added in the production process, or particles containing so-called internal particles precipitated by the reaction of the compound added in the polyester production process may be used.
Further, at the time of producing the polyester, known modifiers and stabilizers which are usually added can be blended.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples.
In the examples, antimony trioxide represents an antimony trioxide-based compound, and parts represent parts by weight. Each measured value in the examples was obtained by the following method.

A. Bismuth element content in antimony trioxide Determined by atomic absorption method.

B. Selenium content in antimony oxide Determined by ICP method.

C. Intrinsic viscosity It measured at 25 degreeC using O-chlorophenol as a solvent.

D. Black foreign matter Polyester was formed into a biaxially stretched film having a thickness of 0.1 mm, which was enlarged by a stereoscopic microscope, and expressed by the number per 1 g of the film by visual observation.

E. Color Tone of Polyester Chip-like polyester was measured with a color machine (manufactured by Suga Test Instruments Co., Ltd.), and indicated by L and b values.

Example 1 To a bis-β-hydroxyethyl terephthalate low polymer (hereinafter referred to as BHT) obtained by subjecting 85.8 parts of TPA and 38.5 parts of EG to an esterification reaction at 260 ° C. for 4 hours, 1.10% of TEG reducing property, Bi
Add 0.025 parts of antimony trioxide with an element content of 48 ppm and Se element content of 13 ppm, 0.06 part of trimethyl phosphate, and 0.12 part of calcium acetate, and carry out polycondensation reaction at 290 ° C. under a reduced pressure of 0.5 mmHg for 3 hours and 10 minutes. Was. The resulting polymer is
b value is 5.0, L value is 41.0, intrinsic viscosity is 0.650, black foreign matter is 0
KO / g. When this polymer was formed into a yarn, a good polyester yarn was obtained with almost no die stain.

Example 2 In Example 1, the added antimony trioxide was TEG.
The procedure was carried out in the same manner as in Example 1 except that the reducing property was changed to 0.95%, the Bi element content was 25 ppm, and the Se element content was 20 ppm. The resulting polyester had a b value of 5.2, an L value of 41.5, an intrinsic viscosity of 0.618, and a black foreign matter of 1 / g. As a result of forming this polymer into a film, there was no stain on the die and the film forming property was good.

Example 3 100 parts of dimethyl terephthalate, 70 parts of (EG), 0.07 part of calcium acetate, 1.20% of TEG reducibility, and 15 pp of Bi element content
m, antimony trioxide having a Se element content of 17 ppm was added, and a transesterification reaction was performed according to a conventional method.
015 parts was added to distill off excess (EG) and bis-β
-Hydroxyethyl terephthalate was obtained. The polyester obtained by subjecting this to polycondensation for 2 hours and 5 minutes according to a conventional method had an intrinsic viscosity of 0.615, a b value of 5.1, and an L value of 40.8, and the number of black foreign substances was 0 / g. When this polyester was formed into a yarn, the spinning property was good and the base was not stained.

Example 4 It carried out by the same method as Example 3 except having changed into antimony trioxide shown in Table 1. The properties of the obtained polyester were good as shown in Table 1.

Comparative Example 1 The same procedure as in Example 1 was carried out except that antimony trioxide having a TEG reducing property of 0.95%, a Bi element content and a 180 ppm Se element content of 7 ppm was used as antimony trioxide. The color of the obtained polyester was dark, and there were many black foreign substances. (Table 1) Comparative Examples 2 and 3 The same procedure as in Example 1 was carried out except that the antimony trioxide shown in Table 1 was used. As shown in Table 1, the obtained polyester had a yellow color tone and many black foreign substances.

Comparative Examples 4 to 7 The same procedures as in Example 3 were performed except that antimony trioxide shown in Table 1 was used. In each case, the obtained polyester was poor in quality.

[Effect of the Invention] The polyester production method of the present invention is a method suitable for obtaining a polyester having a good and stable color tone and a small amount of black foreign matter. In addition, when the obtained polyester is applied to a yarn-forming or film-forming process, a product with less stain on a die and a stable color tone can be obtained.

Claims (1)

(57) [Claims] 1. A process for producing a polyester from an aromatic dicarboxylic acid or a lower alkyl ester thereof and a glycol, wherein the polymerization catalyst is a compound of antimony trioxide, bismuth and selenium, and has a triethylene glycol reducing property. 1.7% or less, the content of the Bi element is 0.1%
A method for producing a polyester, comprising using an antimony trioxide-based compound having a content of Se of 1 ppm to 30 ppm and a content of the Se element of 1 ppm to 30 ppm.