JPS6042810B2 - Polyester manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing polyester, particularly a method for producing polyester,
The present invention relates to a method for producing polyester having excellent moldability and quality.

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

Such polyesters are usually produced by heating a dialkyl ester of terephthalic acid and ethylene glycol to 130 to 250°C, causing a transesterification reaction while distilling off the generated alkanol, and then transesterifying the resulting glycol ester of terephthalic acid and/or its lower weight. Combine under reduced pressure 250
It is produced by heating to ~300°C and causing a polycondensation reaction while distilling the generated 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. 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. In particular, manganese compounds such as manganese acetate are widely used as transesterification catalysts because they have excellent transesterification ability and can yield polyesters of relatively good quality. Furthermore, as a polycondensation catalyst, antimony compounds such as antimony trioxide are most widely used because they have an excellent polycondensation reaction promoting effect and can yield polyesters with relatively good color tone. However, polyesters obtained using a catalyst system of a manganese compound and an antimony compound have a drawback of poor moldability, particularly poor thread-spinning properties.

That is, spinning bag clogging, yarn breakage, etc. are likely to occur during spinning, and wrapping, yarn breakage, etc. are also likely to occur during stretching. stomach.
After investigating these causes, we found that in polyester obtained using a manganese compound-antimony compound catalyst system, insoluble foreign matter is generated in the polymer, which causes a large increase in back pressure during spinning, resulting in a large increase in back pressure. In addition, foreign matter adheres to and grows around the spinning hole during spinning, and when the foreign matter reaches a certain height on the spinneret surface, the polymer flow bends around the spinning hole (hereinafter referred to as "pending"). It was learned that this causes occurrence of lapping and yarn breakage during spinning and drawing.

On the other hand, titanium compounds such as tetrabutyl titanate have also been known as polycondensation catalysts. however,
The use of such titanium compounds is known. Polyester tends to take on a yellowish tinge, and particularly when used in an amount sufficient to achieve industrial production rates, the resulting polyester exhibits a marked yellow color () and its softening point is also lowered. This low softening point causes the generation of scum and staining of the resulting products during processing of molded products, especially fibers and films, especially during high-speed processing. The present inventor has discovered that insoluble foreign matter is not generated in polyester, there is little generation of foreign matter on the spinneret surface during spinning, and moldability is improved.
As a result of intensive research into producing a polyester with good color tone and high softening point, we used a manganese compound and a cobalt compound together in a specific amount and ratio as a transesterification catalyst, and a specific titanium compound as a polycondensation/polymerization catalyst. The present invention has been developed based on the knowledge that the above object can be achieved by using a specific amount of the compound.

That is, in the present invention, a dialkyl ester of a difunctional carboxylic acid, mainly terephthalic acid, and a glycol, mainly ethylene glycol, are transesterified, and the resulting transesterification product is then subjected to a polycondensation reaction to produce a polyester. During production, a manganese compound and a cobalt compound are used as transesterification catalysts according to the following formulas (1) to (
(2) [In the formula, Mn and CO are respectively mmol% of the manganese compound and cobalt compound relative to the dialkyl ester of the bifunctional carboxylic acid] and the polycondensation catalyst is an aromatic polycarboxylic acid or its A product obtained by reacting an anhydride and a tetraalkyl titanate in advance is prepared such that the titanium atoms in the product are 3 to 25 mmol% based on the dialkyl ester of the difunctional carboxylic acid.
This is a method for producing polyester, characterized in that the amount of polyester used is as follows.

In the present invention, the dialkyl ester of difunctional carboxylic acid used as a raw material for polyester is dialkyl terephthalate (the number of carbon atoms in the alkyl group is usually 1).
~4), but a portion (usually 20 mol% or less) of dialkyl esters of other difunctional carboxylic acids, such as isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, and other aromatic acids other than terephthalic acid. aliphatic dicarboxylic acids such as group dicarboxylic acids, adipic acid, sebacic acid,
1●It may be replaced with an alkyl ester such as an alicyclic dicarboxylic acid such as 4-cyclohexane dicarboxylic acid or an oxycarboxylic acid such as 4-(β-oxyethoxy)benzoic acid.

In addition, as for glycol, ethylene glycol is the main target, but a part (usually 20 mol% or less) of it can be used for other diol compounds, such as trimethylene glycol, tetramethylene glycol, etc. with the general formula HO(Cl(2)
Even if it is replaced with an aliphatic glycol represented by NOH (where n is an integer of 3 to 10), an alicyclic glycol such as cyclohexane-1,4-dimethanol, an aromatic glycol such as bisphenol A1, tetrabromobisphenol A, etc. good.

The manganese compound used as a transesterification catalyst in the present invention is not particularly limited as long as it has transesterification ability, and examples include manganese aliphatic carboxylates, aromatic carboxylates, halides,
Among these, particularly preferred are aliphatic carboxylates and aromatic carboxylates of manganese such as manganese acetate, manganese propionate, manganese salicylate, and manganese benzoate.

The cobalt compound used in combination with such a manganese compound can be arbitrarily used as long as it has transesterification ability.

Particularly preferred are cobalt aliphatic carboxylates and halides such as cobalt acetate and cobalt chloride. The amounts of the manganese compound and cobalt compound used are expressed as Mn mmol % for the manganese compound and CO mmol % for the cobalt compound relative to the dialkyl ester of bifunctional carboxylic acid used as a raw material for polyester. Mn is 1 to 30 mmol%, preferably 5 to 25 mmol%, CO is 10 to 50 mmol%, preferably 1
The total amount of both Mn+C within the range of 2 to 40 mmol%
O is 15 to 60 mmol%, preferably 20 to 50 mmol%, and the proportion of the cobalt compound -Sλ- to the total amount of both is 0.25 or more, preferably 0.30
It should be above ~h+CO.

If a cobalt compound is used alone, even if a specific titanium compound described below is used as a polycondensation catalyst, the resulting polyester will contain a large amount of foreign matter and its color tone will deteriorate. Also, if a manganese compound was used alone,
The color tone of the resulting polyester is poor. However, if a cobalt compound and a manganese compound are used together in the above range,
Furthermore, a polyester having excellent moldability and quality can only be obtained by using a specific titanium compound, which will be described later, as a polycondensation catalyst. Any method can be used to add the manganese compound and cobalt compound. For example, it may be added as is, dissolved in glycol or the like, or both may be added separately or after being mixed in advance. The titanium compound used as a polycondensation catalyst in the present invention is a reaction product obtained by reacting an aromatic polycarboxylic acid or its anhydride with a tetraalkyl titanate in advance.

The aromatic polycarboxylic acids used here are preferably divalent or higher benzene polycarboxylic acids that can form anhydrides, such as phthalic acid, trimellitic acid, hemimellitic acid, and pyromellitic acid; Things are also used in the same way. Among these, trimellitic acid and anhydrides thereof are particularly preferred. As the tetraalkyl titanate to be reacted with such an aromatic polyhydric carboxylic acid, tetraisopropyl titanate, tetrapropyl titanate, and tetrabutyl titanate are preferably used. The reaction between the aromatic polycarboxylic acid and the tetraalkyl titanate is carried out by dissolving part or all of the aromatic polycarboxylic acid or its anhydride in a solvent, adding the tetraalkyl titanate dropwise thereto,
, C to 200° C. for about 30 minutes or more.

The reaction pressure at this time is not particularly limited, and normal pressure is sufficient. Note that any solvent that can dissolve part or all of the aromatic polyhydric carboxylic acid can be used, and ethanol, ethylene glycol, benzene, etc. are particularly preferred.
The molar ratio of the aromatic polycarboxylic acid or its anhydride to the tetraalkyl titanate in this reaction can vary over a wide range, but if the amount of tetraalkyl titanate is too large, the color tone and softening point of the resulting polyester tend to deteriorate. On the other hand, if the amount of tetraalkyl titanate is too small, it tends to be difficult for the polycondensation reaction to proceed sufficiently. Preferably, they are used in proportions.

The reaction product of aromatic polycarboxylic acid or its anhydride and tetraalkyl titanate thus obtained (hereinafter referred to as titanium aromatic polycarboxylic acid) can be used as it is or after isolation. However, it may be used after being purified again using acetone or the like.

The amount used is such that the titanium atoms in the titanium aromatic polycarboxylic acid are in the range of 3 to 25 mmol%, preferably 5 to 20 mmol%, based on the dialkyl ester of the difunctional carboxylic acid used as a raw material for polyester. It should be in quantity. If it is less than 3 mmol %, a sufficient polycondensation reaction rate cannot be obtained, and if it is more than 25 mmol %, a decomposition reaction occurs and the resulting polyester becomes colored.

It may be added at any time before the beginning of the polycondensation reaction, or it may be added from the beginning of the transesterification reaction. Further, other polycondensation catalysts such as antimony compounds, germanium compounds, etc. may be used in combination without departing from the purpose of the present invention. As the reaction conditions in the present invention, conventional conditions can be arbitrarily adopted. To explain the case of producing polyethylene terephthalate, dimethyl terephthalate and ethylene glycol are heated at 130 to 250°C in the presence of predetermined amounts of the manganese compound and cobalt compound.
The methanol generated by heating is distilled off. Then, a predetermined amount of titanium aromatic polycarboxylic acid is added and heated to 250 to 300°C under reduced pressure, and polymerization is carried out while distilling off the generated ethylene glycol until the desired degree of polymerization is reached. A method involving a condensation reaction is generally employed. Note that a phosphorus compound may be added as a stabilizer at the stage when the transesterification reaction is substantially completed, and it is preferable to do so. As the phosphorus compound, any commonly used phosphorus compound can be used, but phosphoric acid, phosphorous acid, and alkyl esters thereof are preferable.
Partial alkyl esters are also preferably used. In carrying out the present invention, matting agents such as titanium dioxide, toning agents and coloring agents to improve the color tone, and further modifications such as antistatic agents, flame retardants, and dye-enabling agents are also used. Agents and the like can also be used as desired.

According to the present invention, in the polyester obtained, there is very little generation of insoluble foreign matter caused by the catalyst, and even if it is generated, the particle size is extremely small, so the service life of the bag in the spinning process is greatly extended. Since there are very few foreign substances that adhere to and grow on the spinneret surface, stable spinning for a long period of time is possible.Furthermore, the condition of various processes after spinning is particularly important when spinning using a multi-hole spinneret, and the take-up speed 2500771. /min or more, especially 3000rrL
This is noticeable when spinning at high speeds of /min or more.

Next, the present invention will be explained 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 an orthochlorophenol solvent. The L value and b value, which indicate the color tone of the polymer, are values measured using a Hander-type color difference meter, and the larger the L value, the better the whiteness is. -b) The larger the value, the better the color tone. In addition, the yarn spinning properties of the obtained polyester are 0.3Tn in diameter! Using a spinneret with n spinning holes of 3N, the discharge rate was 80y/min, the discharge rate was 80y/min, and the discharge temperature was 2.
Melt spinning was carried out at 85°C and a winding speed of 1200 m/min for 10 days, during which time the back pressure increase rate (K9/CItG/day) and the growth rate of the height of foreign matter on the spinneret surface around the spinning hole (μ/day) were determined. Indicated. Example 1 1 (1) part of dimethyl terephthalate and 70 fff of ethylene glycol! , and 0.0 parts of manganese acetate (15 mmol% dimethyl terephthalate) and 0.03 parts of cobalt acetate as transesterification catalysts.
'5 (25 mmol % to dimethyl terephthalate) was added and heated from 150°C to 240°C until 33 parts of methanol was distilled out to cause transesterification.

This transesterification reaction required 175 minutes. Next, 0.022 parts of trimethyl phosphace as a stabilizer and 0.033 parts of a reaction product of trimellitic anhydride and tetrabutyl titanate shown below as a polycondensation catalyst (15 mmol % as titanium atoms vs. dimethyl terephthalate) were added. Then, after adding an ethylene glycol slurry containing 0.5 part of titanium dioxide as a matting agent, the temperature was increased while moving to a reduced pressure, and finally the temperature was increased to 27°C under a high reduced pressure of 1 TwtHg or less.
A polycondensation reaction was carried out at 5°C for 4 hours. [η] of the obtained polyester was 0.643s, the softening point was 261.0°C, the color tone was L value 67.0, b value 4.3, and the spinning characteristics were as follows: back pressure increase rate 1.1kg/CltG/impedance Foreign body growth rate 1.0μ
/day, which was very low and good. (Preparation of polycondensation catalyst) Add 0.0 parts of trimellitic anhydride to 2.5 parts of ethylene glycol.
Dissolve 8 parts and add 0.65 parts of tetrabutyl titanate to this.
(1'2 moles of trimellitic anhydride) was added dropwise, and the mixture was maintained at 80°C under normal pressure in air to allow a 6-powder reaction. After cooling to room temperature, 15 parts of acetone was added and the precipitate was reduced to NO. ? It was filtered through paper and dried at 100°C for 2 hours.

The titanium content of the precipitate was 11.5% by weight. Examples 2 and 3 and Comparative Examples 1 and 2 The same procedure as in Example 1 was conducted except that the amount of manganese acetate used as part of the transesterification catalyst in Example 1 was varied as shown in Table 1.

The results were as shown in Table 1. In addition, the amount of manganese acetate used in the table indicates mmol % based on dimethyl terephthalate. Examples 4 and 5 and Comparative Examples 4 and 5 The same procedure as in Example 1 was conducted except that the amount of cobalt acetate used as part of the transesterification catalyst in Example 1 was varied as shown in Table 2.

The results were as shown in Table 2. The amount of cobalt acetate used in the table indicates mmol % based on dimethyl terephthalate. Examples 6 and 7 and Comparative Examples 5 and 6 Example 1 except that the amount of the reaction product of trimellitic anhydride and tetrabutyl titanate used as the polycondensation catalyst in Example 1 was varied as shown in Table 3. I did the same thing.

The results were as shown in Table 3. The amount of titanium compound used in the table indicates the millimole% of titanium atoms in the reaction product of trimellitic anhydride and tetrabutyl titanate relative to dimethyl terephthalate. Examples 8 to 11 and Comparative Examples 7 to 9 The same procedure as in Example 1 was carried out except that the transesterification catalyst system shown in Table 4 was used in place of the transesterification catalyst system used in Example 1.

The results were as shown in Table 4. The amount of transesterification catalyst used in the table is mmol % based on dimethyl terephthalate. Example 12 The reaction product of trimellitic anhydride and tetrabutyl titanate used as a polycondensation catalyst in Example 1 was replaced with the following trimellitic acid and tetrabutyl titanate. 0.019 parts of reaction product with trabutyl titanate (15 parts as titanium atoms)
The same procedure as in Example 1 was carried out except that mmol% of dimethyl terephthalate was used.

[η] of the obtained polyester was 0.641, the softening point was 260.9°C, the color tone was L value 67.1, b value 4.5, and the spinning characteristics were back pressure increase rate 1.2k9/CltG/ The foreign body growth rate was 0.9μ/day. (Preparation of polycondensation catalyst) 0.80 parts of trimellitic acid was dissolved in 2.5 parts of ethanol, and 0.6 parts of tetrabutyl titanate was dissolved in this. (112 moles vs. trimellitic acid) was added dropwise and maintained at 80°C under normal pressure in air to cause a 6-powder reaction, then cooled to room temperature, 15 parts of acetone was added, and the precipitate was separated into NO. It was filtered through 5-filter paper and dried at 100°C for 2 hours.

The titanium content of the precipitate was 11.5% by weight. Example 13 In place of the reaction product of trimellitic anhydride and tetrabutyl titanate used as a polycondensation catalyst in Example 1, 0.020 parts of the reaction product of hemimelitic acid and tetrabutyl titanate shown below (titanium atom The same procedure as in Example 1 was carried out except that 15 mmol % of dimethyl terephthalate was used.

The obtained polyester has a [η] of 0.648, a softening point of 260.9°C, a color tone of L value 66.8, and a b value of 4.0, and its spinning characteristics include a back pressure increase rate of 1.3k9/c! The foreign body growth rate was 1.4 μ/day. (Preparation of polycondensation catalyst) 0.80 parts of hemimellitic acid was dissolved in 2.5 parts of ethanol, and 0.6 parts of tetrabutyl titanate was dissolved in this. (1 mole of hemimellitic acid) was added dropwise and kept at 80°C under normal pressure in air to cause a powder reaction, then cooled to room temperature, and acetone 1
5 parts was added and the precipitate was reduced to NO. ? Pass it through paper for 10 minutes.
It was dried at 0°C for 2 hours.

Claims (1)

[Claims] 1. A dialkyl ester of a difunctional carboxylic acid, mainly terephthalic acid, and a glycol, mainly ethylene glycol, are transesterified, and the resulting transesterification product is then subjected to a polycondensation reaction. In producing polyester, manganese compounds and cobalt compounds are used as transesterification catalysts according to the following formulas (I) to (IV) 1≦
Mn≦30 (I) 10≦Co≦50 (II) 15≦Mn+Co≦60 (III) 0.25≦Co/(Mn+Co) (IV) [In the formula,
Mn and Co represent mmol% of the manganese compound and cobalt compound, respectively, based on the dialkyl ester of the difunctional carboxylic acid. ] A product obtained by reacting an aromatic polycarboxylic acid or its anhydride and a tetraalkyl titanate in advance as a polycondensation catalyst is used in an amount that satisfies all of the above. A method for producing polyester, characterized in that the amount is used in an amount of 3 to 25 mmol % based on the dialkyl ester of carboxylic acid. 2. The reaction product used as a polycondensation catalyst is a combination of a tetraalkyl titanate and an aromatic polyhydric carboxylic acid or its anhydride in a ratio of 1/2 to 2 (1/2) mol per 1 mol of the tetraalkyl titanate. A method for producing polyester according to claim 1, which is a reaction product. 3 Claims in which the tetraalkyl titanate that is one component of the reaction product used as a polycondensation catalyst is at least one kind of tetraalkyl titanate selected from the group consisting of tetraisopropyl titanate, tetrapropyl titanate, and tetrabutyl titanate. A method for producing polyester according to item 1 or 2. 4 The aromatic polycarboxylic acid or its anhydride, which is one component of the reaction product used as a polycondensation catalyst, is at least one compound selected from the group consisting of trimellitic acid, hemimellitic acid, and anhydrides thereof. A method for producing polyester according to any one of claims 1 to 3. 5. Production of polyester according to any one of claims 1 to 4, wherein the manganese compound is at least one manganese compound selected from the group consisting of manganese aliphatic carboxylates and manganese aromatic carboxylates. Law. 6 Claims 1 to 5, wherein the cobalt compound is at least one cobalt compound selected from the group consisting of aliphatic carboxylic acid cobalt and cobalt halide.
A method for producing polyester according to any one of paragraphs.