JPS6026137B2 - Polyester manufacturing method - Google Patents

Description

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

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

Such polyesters, for example, polyethylene terephthalate, are usually produced by heating the dialkyl ester of terephthalic acid and ethylene glycol to 130 to 250oC, causing a transesterification reaction while distilling off the alkali/alcohol generated, and then converting the resulting terephthalic acid into ethylene. It is produced by heating a glycol ester and/or its low polymer under reduced pressure to 250 to 30 ppm and subjecting it to a polycondensation reaction while distilling off the generated ethylene glycol.

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 polyester fibers and films, and attempts have been made to increase molding speed to increase productivity. The generation of is a serious obstacle in both cases. The present inventors have focused on the fact that even if such insoluble 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 a method for making the generated non-falling foreign matter fine, the inventor has found that the production reaction of polyester can be improved. It has been found that insoluble foreign substances in polyester can be finely dispersed if a specific isophthalic acid component and 4-carboxypenzaldehyde acid are present in specific amounts.

The present invention was completed as a result of further research based on this knowledge. That is, in producing a polyester by heat-reacting a dialkyl ester of a difunctional carboxylic acid, mainly terephthalic acid, with at least one type of glycol, the present invention provides a mono- and/or dialkyl ester of 'a' isophthalic acid. Stell and 'b' 4-carboxybenzaldehyde acid are present in an amount such that (a) component 5 or more, {b) component 5 or more, and the total amount of {a' and 'b} components does not exceed 100 squares, The present invention is also a method for producing polyester, characterized in that the reaction is carried out in the substantial absence of monoalkyl esters of P-tolylic acid and/or terephthalic acid.

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

In addition, a part of it may be a difunctional carboxylic acid other than terephthalic acid or isophthalic acid, such as naphthalene dicarboxylic acid,
Alkyl esters such as phthalic acid, adipic acid, sebacic acid, and 4-(8-hydroxyethoxy)benzoic acid may be substituted. In addition, the main glycol is ethylene glycol, but glycols represented by ○ (C ratio) nOH (where n is an integer from 3 to 10) such as propylene glycol and tetramethylene glycol may also be used. Furthermore, a portion of the main glycol may be replaced by other of the above-mentioned 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 them, calcium compounds, manganese compounds,
It is preferable to use a magnesium compound, a zinc compound, and a cobalt compound alone or in combination of two or more, and the amount used is preferably 0.01 to 0.1 mol % based on the bifunctional carboxylic acid component used as a raw material for polyester. Further, as a 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 0.00% relative to the difunctional carboxylic acid component.
．． 1 mol%, especially 0.015 for antimony compounds
~0.05 mol% is preferred. Isophthalic acid dialkyl ester, which is component 'a), used in the present invention to refine insoluble foreign substances generated in polyester;
As the isophthalic acid monoalkyl ester, carbon number is 1
-4 lower alkyl esters are preferred, and methyl esters are particularly preferred. These alkyl esters may be used alone or in combination of two or more. The amount of {a} isophthalic acid mono- and/or dialkyl ester and 'b' 4-carboxybenzaldehyde acid used is such that the 'a' component in the obtained polyester is at least 5 sides and the 'b' component is at least 5 sides. and the total amount of {a decrement and (b' component) should not exceed 100 blood.

If the amount used does not reach the above specified amount, the effect of micronizing the insoluble foreign matter generated in the polyester will be small; on the other hand, if it is too large, the physical properties such as softening point of the resulting po-IJ ester may decrease, and even The progress of the polycondensation reaction is delayed, resulting in coloring, deterioration of physical properties, etc. A particularly preferred usage amount is up to about 800 legs. Also, the above
In addition to the a-component and 'b' component, a compound such as an alkyl ester of 4-carboxybenzaldehyde acid may also be included, and in such a case, the above {a-component, 'b' component and The total amount should be 100 or less. If these compounds are added after the insoluble foreign matter is formed in the polyester, it will not be possible to make the formed foreign matter fine, so they should be added before the insoluble foreign matter is formed in the polyester. It is preferable to add it before the start of exchange, and it may be contained in advance in the dialkyl ester of difunctional carboxylic acid used as the polyester raw material.

Also, in the present invention, phosphorus compounds can be used as stabilizers, and this is also preferred.

Any phosphorus compound that can be used as a stabilizer for polyester can be used as the phosphorus compound, but phosphoric acid, phosphorous acid, and mono-, di-, or tri-esters thereof are preferred, and the esters have 1 to 1 carbon atoms. The alkyl ester and phenyl ester of No. 6 are preferred. Also preferred are reaction products obtained by heat-treating these alkyl esters in glycol, particularly ethylene glycol. 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 polyester obtained has extremely fine insoluble foreign matter caused by the catalyst generated therein, so that the molding process proceeds smoothly.

For example, in the spinning process, the pressure increase rate of the yarn pack is extremely small, which makes it possible to significantly extend the service life of the pack, and the drawability of the spun fibers is also extremely good, further increasing the spinning speed. It becomes easy to increase the stretching 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,
A scale retardant, a hydrophilic agent, 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, [knife] is the intrinsic viscosity determined from the value measured at 3000 in orthochlorophenol solution, and the color tone of the polymer is the L value measured using a Hunter color difference meter. Shown as a 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 matter is
After adding 15 parts of anchorage and completely decomposing the polymer under reflux at 190 qo for 3 hours, a vacuum oven was carried out using furnace paper with a mesh size of 31 to remove foreign substances on the furnace paper. was observed using a microscope with a magnification of 20 needles, and measured by the counting method. The pack pressure increase rate is 3 holes in the polymer.
It is shown as the pressure increase rate of the paper yarn pack when melting paper yarn at a rate of 40 mm using a No. 6 porous nozzle. Examples 1 and 2
and Comparative Examples 1 and 2 Dimethyl isophthalate (DMI) and 4-carboxybenzaldehyde acid (CB
Generated by heating 100 parts of dimethyl terephthalate containing A), 7 parts of ethylene glycol, and 0.063 parts of calcium acetate (0.069 mol% to dimethyl terephthalate) as a transesterification catalyst from 150 to 240 o'clock. The transesterification reaction was carried out while distilling off methanol.

Next, 0.029 parts of phosphorous acid was added as a stabilizer, 0.04 parts of antimony trioxide was added as a polycondensation catalyst, and an ethylene glycol slurry containing 0.5 parts of titanium dioxide was added as a matting agent. Under reduced pressure below 285q0
The mixture was heated for 4 hours 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. As is clear from the table,
In the case of Examples 1 and 2 according to the present invention, the particle size of the insoluble foreign matter in the polymer is finer than in Comparative Examples 1 and 2 which are out of the scope of the present invention, and the pack pressure increase rate is also extremely low. Table 1 Example 3 Dimethyl isophthalate 15 parts, isophthalic acid/methyl 14 parts, 4-carpoxybenzaldehyde acid 5 and methyl 4-carboxybenzaldehyde 103 parts, combined dimethyl terephthalate 100 parts, ethylene Glycol 7 base, zinc acetate 0.0 as transesterification catalyst
1 part and 0.01 part of cobalt acetate as a color toner.
Heated to ~240°C to transesterify, then ethylene glycol containing 0.025 parts of trimethyl phosphate as a stabilizer, 0.03 parts of antimony trioxide as a polycondensation catalyst, and 0.4 parts of titanium oxide as a matting agent. The slurry was added and heated to 285 pm under reduced pressure of 1 mm Hg or less to carry out a military condensation reaction.

The results are shown in Table 2. Example 4 18 parts of dimethyl isophthalate, 3 parts of monomethyl isophthalate, 11 parts of 4-carboxybenzaldehyde acid, 100 parts of dimethyl terephthalate containing 101 parts of methyl 4-carboxybenzaldehyde, 7 parts of ethylene glycol, and ester Manganese acetate 0.0 as an exchange catalyst is heated to 150-24000 to transesterify, and then trimethyl phosphate 0.0 is used as a stabilizer.
22 parts were heat-treated in ethylene glycol, ethylene glycol slurry containing 0.04 parts of antimony trioxide as a polycondensation catalyst and 0.5 parts of titanium dioxide as a matting agent was added, and the mixture was heated to 285 qo under a reduced pressure of 1 Hg. was heated to cause a polycondensation reaction.

The results are shown in Table 2. Table 2

Claims (1)

[Claims] 1. In producing a polyester by heating and reacting a dialkyl ester of a difunctional carboxylic acid, mainly terephthalic acid, with at least one type of glycol, (a) a mono- and/or dialkyl isophthalic acid; ester and (b)
4-carboxybenzaldehyde acid (a) component 50p
pm or more (b) component 5 ppm or more and (a) component and (b)
A method for producing a polyester, characterized in that the total amount of the components is present in an amount not exceeding 1000 ppm, and the reaction is carried out in the substantial absence of a monoalkyl ester of P-toluic acid and/or terephthalic acid. 2. The method for producing a polyester according to claim 1, wherein the mono- and/or dialkyl ester of isophthalic acid is an alkyl ester having 1 to 4 carbon atoms.