JPS6026138B2 - Polyester manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyester, and particularly to a method for producing polyester with finer foreign matter and excellent moldability, quality, and hue.

Polyesters, especially polyalkylene terephthalates, have many excellent properties and are therefore widely used in various applications, especially in fibers and films.

Such polyesters, such as polyethylene terephthalate, are usually produced by heating the dialkyl ester of terephthalic acid and ethylene glycol to 130 to 250°C and carrying out a transesterification reaction while distilling off the alkanol generated.
Next, the produced ethylene glycol ester of terephthalic acid and/or its low polymer was heated at 250 to 300° under reduced pressure.
It is produced by heating to 0 and causing a polycondensation reaction while eluting the ethylene glycol generated.

The polyester thus obtained is extruded in a molten state into a fiber or film form through fine holes (spinning holes) or slits, and then stretched for practical use. Also,
In producing the above-mentioned polyester, a catalyst is necessary for the reaction to proceed smoothly, and various metal compounds have been proposed as such catalysts.

However, insoluble foreign substances due to the catalyst are generated in the resulting polyester, which causes various troubles during the molding process, particularly during extrusion and stretching into a fiber or film form. Particularly recently, there have been many demands for fine denier, thinner, and higher quality fibers and films made of POIJ esters, and efforts have also been made to increase molding speeds to improve productivity. Generation becomes a serious obstacle in both cases. The present inventors have focused on the fact that even if such non-flammable foreign matter is generated, it will not cause the above-mentioned hindrance if it is made fine, and as a result of intensive research on methods for making the generated insoluble foreign matter fine, the inventors have found that the production reaction of polyester is I learned that if a specific aldehyde component is present in a specific amount, the undesirable and foreign substances in polyester can be finely dispersed.

However, the polyester obtained by adding such an aldehyde component has the disadvantage that the hue deteriorates. On the other hand, in order to improve the hue of polyester, a method has been proposed in which the reaction is carried out in the presence of an aromatic aldehyde acid and a cobalt compound when manufacturing polyester (Japanese Patent Publication No. 4
8-133280).

However, when this method was studied, it was found that the use of an aldehyde component and a cobalt compound actually worsened the hue of the polyester obtained. As a result of intensive studies on the deterioration of hue caused by aldehyde components, the inventors of the present invention found that the cause of this deterioration in hue was due to the interaction between the aldehyde component and unpleasant compounds that are generally added as stabilizers during the production of polyester. We presumed that, and further investigated various phosphorus compounds, and found that if a specific amount of a specific phosphorus compound is used as a stabilizer, even if an aldehyde component is used, or even if an aldehyde component and a cobalt compound are used together. The present invention was developed based on the knowledge that the hue of the polyester obtained does not deteriorate.

That is, the present invention involves transesterifying a dialkyl ester of a difunctional carboxylic acid, mainly terephthalic acid, with at least one type of glycol, and then subjecting the transesterification product to a military condensation reaction to produce a polyester. , 4-carboxybenzaldehyde acid and/or its alkyl ester is added to the dialkyl ester of the difunctional carboxylic acid until the transesterification reaction is completed.
．． 005 to 0.15 mol% and after the transesterification reaction is substantially completed, the following general formula [wherein R1, R2
and R3 represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of R1, R2 and R3 is an alkyl group.

0.01 to 0.5 of the dialkyl ester of the bifunctional carboxylic acid.
This is a method for producing polyester characterized by adding mol%.

The difunctional carboxylic acid used as a raw material for polyester in the present invention is mainly terephthalic acid, and the dialkyl ester is preferably an alkyl ester having 1 to 4 carbon atoms, with dimethyl ester being particularly preferred.

In addition, some of them, such as isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, adipic acid, sebacic acid, 4-
It may be replaced with a dialkyl ester such as (P-hydroxyethoxy)benzoic acid. The main glycol is ethylene glycol, but glycols such as propylene glycol and tetramethyl glycol represented by NOH (where n is an integer from 3 to 10) may also be used. A portion of the main glycol may be replaced by other of the above glycols or other diol compounds. -
Any catalyst can be used in the transesterification reaction between the dialkyl ester of the difunctional carboxylic acid and the glycol and the subsequent polycondensation reaction. Among these, as the transesterification catalyst, it is preferable to use calcium compounds, manganese compounds, magnesium compounds, and zinc compounds alone or in combination of two or more, and the amount used is 0.00% relative to the bifunctional carvone brewing component used as the raw material for polyester. 0
1 to 0.1 mol% is preferred. As the polycondensation catalyst, it is preferable to use an antimony compound, a titanium compound, or a germanium compound alone or in combination, and the amount used is 0.003 to 0.1 mol% based on the Ninomiya functional carboxylic acid component.
In particular, in the case of antimony compounds, 0.015 to 0.05 mol% is preferable. In the present invention, the aldehyde component used to refine the persistent foreign matter generated in the polyester is 4-carboxybenzaldehyde acid or its alkyl ester, and the alkyl ester is particularly preferred.

Further, as the alkyl ester, an alkyl ester having 1 to 4 carbon atoms is preferable, and a methyl ester is particularly preferable. These aldehyde components may be used alone or in combination of two or more. The amount of these aldehyde components used is 0.0% relative to the dialkyl ester of the difunctional carboxylic acid used as the raw material for polyester.
The range is from 0.05 to 0.15 mol%.

If the amount of the aldehyde component used does not reach the above specified amount, the effect of micronizing insoluble foreign substances generated in the polyester will be small; on the other hand, if the amount is too large, the resulting polyester will have poor physical properties at the softening point, and even become disarmament. The progress of the reaction is delayed, resulting in coloring, deterioration of physical properties, etc.
A particularly preferable usage amount is 0.008 to 0.08 mol%. If these aldehyde components are added after insoluble foreign substances have been formed in the polyester, it is not possible to make the formed foreign substances fine.
It should be added before sexual foreign substances are formed, and it is especially preferable to add it before the start of transesterification. Good too. In addition, the scale compound used as a stabilizer in the present invention has the following general formula (
However, R1, R2 and R3 are hydrogen atoms or have 1 or more carbon atoms. ~
4, and at least one of R1, R2 and R3 is an alkyl group.

) of phosphoric acid, and may also be a reaction product obtained by heat-treating such alkyl esters in glycol, particularly ethylene glycol. Such phosphorus compounds may be used alone or in combination of two or more. If such a phosphorus compound is used, the hue of the resulting polyester will not be deteriorated even if the aldehyde component is used. The amount of the above-mentioned ant compound used is 0.00% relative to the dialkyl ester of difunctional carboxylic acid used as a raw material for polyester.
The range is 0.01 to 0.5 mol%.

If the amount of the phosphorus compound used does not reach the above specified amount, the hue of the polyester obtained will deteriorate; on the other hand, if it is too much, the physical properties such as softening point of the obtained polyester may decrease, or the progress of the polycondensation reaction may be delayed. As a result, coloration, deterioration of physical properties, etc. will occur. A particularly preferable usage amount is 0.02 to 0.
It is 2 mol%. The phosphorus compound is added at the time when the transesterification reaction is almost completed, preferably when the transesterification reaction rate reaches 90% or more. The addition method may be arbitrary, and it may be added as is or after being dispersed or dissolved in glycol, particularly ethylene glycol. According to the present invention, the obtained polyester exhibits a good color hue, and the insoluble foreign matter caused by the catalyst generated therein is extremely finely divided, so that the molding process proceeds smoothly.

For example, in the paper yarn process, the pressure increase rate of the spinning pack is extremely small, which makes it possible to significantly extend the service life of the pack, and the drawability of the graded fibers is also extremely good, and furthermore, the rate of increase in the pressure of the spinning pack is extremely small. This makes it easier to increase the drawing speed. In carrying out the present invention, a matting agent such as titanium dioxide, a coloring agent such as a cobalt compound, a coloring agent, an antistatic agent,
Key combustion agents, hydrophilic agents, etc. may also be used as necessary.

Next, the present invention will be explained in further detail by giving examples.

In the examples, parts indicate parts by weight, [ri] is the intrinsic viscosity determined from the value measured at 300 mm in orthochlorophenol solution, and the color tone of the polymer is the L value measured using a Hunter color difference meter. is expressed as b value. The larger the L value, the better the whiteness, and the larger the b value, the stronger the yellowness. In addition, the particle size distribution of insoluble foreign substances was determined by adding 2 parts of polymer and 15 parts of ethylene glycol, and
After completely decomposing the polymer at 90°C for 3 hours, it was passed through a vacuum oven using oven paper with a mesh size of 3. The foreign matter on the oven paper was observed with a sound microscope with a magnification of 20, and measured by the counting method. did. The pack pressure increase rate was expressed as the pressure increase rate of the paper yarn pack when the polymer was melt-spun at a rate of 40 min/min using a porous die with 36 holes. Examples 1 and 2 and Comparative Examples 1 and 2 10 parts of dimethyl terephthalate containing methyl 4-carboxybenzaldehyde (MCB) in the amounts shown in Table 1, 7 parts of ethylene glycol, and calcium acetate as a transesterification catalyst. 0.063 parts (0.063 parts)
069 mol% to dimethyl terephthalate) from 150 to 24
A transesterification reaction was carried out while heating to 0 qo and distilling off the generated methanol. Next, 0.02 parts of various scale compounds of the first notation were added as stabilizers, 0.04 parts of antimony trioxide as a polycondensation catalyst, and ethylene glycol slurry containing 0.5 parts of titanium dioxide as a matting agent. was added and heated at 285 oo for 4 hours under a reduced pressure of 1 side Hg or less to cause a polycondensation reaction. Table 1 shows the weight, softening point, color tone, particle size distribution of insoluble foreign matter, and pack pressure increase rate of the obtained polymer. In Table 1, MOB: Methyl 1-carboxybenzaldehyde MPP: 50 mol of dimethyl phosphate and 5 mol of monomethyl phosphate
Example 3 for dimethyl terephthalate: Dimethyl terephthalate 100 containing 4-carboxybenzaldehyde acid (CB) and methyl 4-carboxybenzaldehyde (MCB) in the amounts shown in Table 2 7 parts of ethylene glycol, 0.01 part of zinc acetate as a transesterification catalyst, and 0.01 part of cobalt acetate as a coloring agent are heated to 15.0 to 24,000 to transesterify, and then the second notation as a stabilizer is used. Adding an ethylene glycol slurry containing 0.025 parts of various phosphorus compounds, 0.03 parts of antimony trioxide as a polycondensation catalyst, and 0.4 parts of titanium dioxide as a matting agent,
Polycondensation reaction was carried out by heating to 285 qo under reduced pressure of 1 Hg or less.

The results are shown in Table 2. In Table 2, OB; 4-carboxybenzaldehyde acid MOB; methyl 4-carboxybenzaldehyde TMP; trimethyl phosphate mole; molar example for dimethyl terephthalate 4-4-carboxypenza as an aldehyde component to be added The same procedure as in Example 3 was carried out except that only 0.008 mol % of aldehydic acid (CB) was added.

The results are shown in Table 3. Table 3

Claims (1)

[Claims] 1. A process for producing a polyester by transesterifying a dialkyl ester of a difunctional carboxylic acid, mainly terephthalic acid, with at least one glycol, and then subjecting the transesterification product to a polycondensation reaction. Before the transesterification reaction is completed, the amount of 4-carboxybenzaldehyde acid and/or its alkyl ester is 0.005 to 0 relative to the dialkyl ester of the bifunctional carboxylic acid.
．． After adding 15 mol% and substantially completing the transesterification reaction, the following general formula ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, R^1, R^2 and R^3 are hydrogen atoms or carbon atoms] Indicates an alkyl group of numbers 1 to 4, R^1, R^2 and R
At least one of ^3 is an alkyl group. ] At least one phosphorus compound represented by
．． A method for producing polyester characterized by adding 5 mol%.