JPS6249296B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for efficiently producing a polyester consisting of alkylene diphenyl-4,4'-carboxylate units or a copolyester containing 25 mol% or more of the above units. A polyester in which 25 to 100 mol% of the total dicarboxylic acid component is composed of diphenyl-4,4'-dicarboxylic acid and whose diol component is composed of alkylene glycol has a secondary property compared to, for example, the corresponding polyalkylene terephthalate. It has various properties such as a high dislocation point and good heat resistance, but when manufacturing this polyester,
There are problems in that the esterification reaction is difficult to proceed in the preliminary stage of the polycondensation reaction, and the transesterification reaction is extremely costly, which is a major hindrance to the efficient production of such polyesters. Specifically, when trying to directly esterify diphenyl-4,4'-dicarboxylic acid and alkylene glycol, the reaction progresses extremely slowly, and impurities are produced significantly due to side reactions, so efficient esterification is difficult. It is impossible to carry out the reaction. Furthermore, when transesterification is carried out, the reaction time is shortened and side reactions are reduced, but it is extremely difficult to produce an esterified product (e.g. dimethyl ester) of diphenyl-4,4'-dicarboxylic acid used as a raw material. For example, as shown in Japanese Patent Application Laid-Open No. 49-43950, it is necessary to use 10 times or more mole of alcohol relative to diphenyl-4,4'-dicarboxylic acid, which increases the cost considerably and makes it impossible to achieve an efficient reaction. No, no. Therefore, the present inventors directly used diphenyl-4,4'-dicarboxylic acid to obtain alkylene diphenyl-4,4'-dicarboxylate units.
As a result of intensive studies aimed at efficiently producing polyester containing 25 to 100 mol%, we found that the esterification reaction prior to the polycondensation reaction was carried out in the presence of a preformed esterification reactant and/or transesterification reactant. Diphenyl-
By feeding 4,4'-dicarboxylic acid and alkylene glycol separately, the reaction rate is increased,
The present invention was achieved by discovering that the desired polyester can be obtained efficiently. That is, the present invention provides ethylene diphenyl-4.
When producing a polyester containing 25 to 100 mol% of 4'-dicarboxylate units, an aromatic dicarboxylic acid containing 0 to 100 mol% of diphenyl-4,4'-dicarboxylic acid or its ester-forming derivative and an alkylene Diphenyl-4 is added to a system in which an esterification reaction product and/or a transesterification reaction product consisting of glycol is pre-existing in an amount of 25% by weight or more based on the diphenyl-4,4'-dicarboxylic acid supplied below. - Continuously or intermittently supply a mixture of 4'-dicarboxylic acid or diphenyl-4,4'-dicarboxylic acid and the remaining aromatic dicarboxylic acid and alkylene glycol to carry out the esterification reaction, and then carry out the esterification reaction. The present invention provides a method for producing polyester, which is characterized by polycondensing reactants. In the present invention, when diphenyl-4,4'-dicarboxylic acid is directly subjected to esterification reaction, diphenyl -4,4'-dicarboxylic acid and alkylene glycol are supplied separately, and the aromatic dicarboxylic acid component of the esterification reaction product and/or transesterification product is diphenyl-4,4' - The dicarboxylic acid may be contained in an amount of 100 mol % or less, or may not be contained at all, and an efficient reaction can be carried out from this point of view as well. Moreover, according to the present invention, the esterification reactant previously formed by the method of the present invention can be reused in the esterification reaction system. Aromatic dicarboxylic acids other than diphenyl-4,4'-dicarboxylic acid used in the present invention include terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, diphenyl-3,3'-dicarboxylic acid, and diphenyl-2,4'-dicarboxylic acid. Examples include 2'-dicarboxylic acid, but terephthalic acid is most preferably used from the viewpoint of the properties of the final copolymerized polyester. In addition, alkylene glycols include ethylene glycol, 1,4-butanediol, 1,
Examples include 6-hexanediol, but it is most desirable to use ethylene glycol. The esterification reactant and/or the transesterification reactant pre-existing in the esterification reaction system may be formed according to a conventional method or the method of the present invention, and the amount of these used is determined by the amount of diphenyl-4, which is supplied below. The amount is at least 25% by weight, preferably at least 40% by weight, based on the 4'-dicarboxylic acid. The amount of esterification reactant and/or transesterification reactant is
If it is less than 25% by weight, the esterification reaction rate becomes extremely slow, making it impossible for the reaction to proceed efficiently, which is not preferable. Alkylene glycol and diphenyl-4, which are supplied to an esterification reaction system in which an esterification reaction product and/or a transesterification reaction product are present
The molar ratio of 4'-dicarboxylic acid or diphenyl-4,4'-dicarboxylic acid to the remaining aromatic dicarboxylic acid is 1.05 to 4.0, particularly preferably 1.20 to 2.0, and since these have poor slurry properties, they should not be mixed. It is important to supply the components separately to the reaction system. Therefore, for example, it is possible to charge the entire amount of alkylene glycol together with the esterification reaction product and/or transesterification reaction product into the reaction system in advance, and then continuously or intermittently supply diphenyl-4,4'-dicarboxylic acid to this system. is preferred. In addition, other dicarboxylic acids and diol components other than the aromatic dicarboxylic acid and alkylene glycol, such as adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, 1,4-cyclohexanedimethanol, 2,2' -bis(4-β-hydroxyethoxyphenyl)propane, 4,4′-bis(β-
It may contain a small amount of hydroxyethoxyphenyl) sulfone, etc. The esterification reaction can be carried out either under normal pressure or under increased pressure, but the gauge pressure is 1.0 Kg/cm ² or less
Preferably, it is optimal to carry out at 0.45 Kg/cm ² or less. Generally, the esterification reaction time can be shortened by pressurizing the reaction, but if the gauge pressure is 1.0Kg/cm ²
If it is larger, it is not preferable because the by-product of diethylene glycol may be promoted during the esterification reaction. Esterification reaction temperature is 200-270℃, preferably
The range of 230 to 260℃ is suitable, and the reaction temperature is 200℃.
Below 270°C, the esterification reaction time becomes longer.
If the temperature is higher than 0.degree. C., the by-product of diethylene glycol increases and the reaction system may be colored, which is not preferable. Note that during the esterification reaction, ethylene glycol can be extracted from a rectification column or the like to suppress the production of diethylene glycol. Furthermore, if an esterification catalyst such as a titanium compound such as tetrabutyl titanate or a tin compound such as monobutyltin oxide is used during the esterification reaction, the reaction time can be significantly shortened. In this way, the esterification reaction rate is over 90%,
The esterification reaction is preferably carried out until the concentration is 95% or more, but the reaction rate is accelerated by the action of the esterification reactant and/or the transesterification reactant previously present in the reaction system, and the production of by-products such as diethylene glycol is prevented. is suppressed, and a stable and efficient esterification reaction can be carried out. After filtering the generated esterification reaction product through a suitable filter to remove foreign substances, if necessary, a polycondensation catalyst such as an antimony compound or a titanium compound or a heat resistant agent such as a phosphorus compound is added to the product for immediate polycondensation. However, at this time, the esterification reaction rate was 90%.
If it is less than this, diphenyl-4,4'-dicarboxylic acid is likely to be captured by the filter, and polycondensation reactivity is lowered, which is not preferable. There are no particular restrictions on the polycondensation reaction conditions, but ethylene diphenyl-4,4'-dicarboxylate/ethylene terephthalate in which the ethylene diphenyl-4,4'-dicarboxylate unit is in the range of 40 to 70 mol%. When polycondensing a copolymer, start reducing the pressure when the temperature inside the polymerization vessel is in the range of 230 to 260℃, and when the degree of vacuum reaches 10 mmHg, reduce the temperature inside the polymerization vessel to 260 to 310℃.
It is preferred to carry out the polycondensation in the range of .degree. The content of alkylene diphenyl-4,4'-dicarboxylate units in the final polyester should be selected to be 25 to 100 mol%; if it is less than 25 mol%, the esterification reaction will not proceed easily. However, this is not preferred because the physical properties of the resulting polyester are not much different from those of the corresponding polyalkylene terephthalate. The most preferred composition of the polyester obtained in the present invention is polyethylene diphenyl-4,4'-
It is a copolymerized polyester containing 40 to 80 mol% of dicarboxylate units and 60 to 20 mol% of polyethylene terephthalate units, and is superior to polyethylene terephthalate in terms of melting point, crystallization properties, melt moldability, heat resistance, etc. Due to its properties, it is useful in fields such as fibers, films, and molded products. The effects of the present invention will be further explained below with reference to Examples. Note that the numbers in the examples indicate parts by weight. Example 1 The esterification reaction rate of terephthalic acid and ethylene glycol was 97.2%.

[Formula] The amounts of each of the esterification reactants shown in Table 1 with a unit molar ratio of 1.24 and 20 parts of ethylene glycol were stored at 240°C in a reactor at normal pressure, and tetrabutyl titanate (0.02% by weight based on the polyester produced) was stored in a reactor at normal pressure. ) was added. Then, 43.6 parts of diphenyl-4,4'-dicarboxylic acid was continuously fed at a constant rate over 4 hours at a gauge pressure of 0.45 kg/cm ² or less. The reaction system was kept at 230-245°C during supply, and after slurry supply was completed, the reaction system was kept at 230-245°C until the esterification reaction rate reached 98%.
Maintained at 230-250℃, and the molar ratio from the rectification column was 1.4.
The esterification reaction was carried out while extracting ethylene glycol. Diphenyl-4・4'-
Esterification reaction rate after completion of supply of dicarboxylic acid is 98
Table 1 shows the time required to reach %.

[Table] Stealization hardly progresses.
From the results in Table 1, it is clear that diphenyl-4, which supplies the esterification reaction product to the esterification reaction system in advance
When present in an amount of 25 mol% or more based on the 4'-dicarboxylic acid, the esterification reaction time can be extremely shortened. Next, each esterification reaction product of Experiment Nos. 4 and 5 was passed through a 200-mesh wire mesh filter, then transferred to a polymerization can, and antimony trioxide was added to it.
0.03% by weight, 0.01% by weight of cobalt acetate and 85%
Add 0.01% by weight of phosphoric acid (based on polyester produced), immediately reduce pressure and heat the polycondensation system (reduce the degree of vacuum to 1 mmHg or less in 60 minutes and simultaneously raise the temperature to 288°C).
The polycondensation reaction was carried out over a period of approximately 4 hours and 30 minutes until a polymer having an intrinsic viscosity of 0.71 was obtained. The melting point of each polymer obtained was 269℃ (No.
4) and 223°C (No. 5), and strong films, fibers, and molded products could be obtained from these polymers. Example 2 Monobutyl tin oxide ( 0.05% by weight of polyester produced) was added along with 23.5 parts of ethylene glycol. For this system,
Diphenyl-4,4'-dicarboxylic acid 43.6 at 240℃
(60 mol % of the dicarboxylic acid component) was continuously added over a period of 3 hours, and it was confirmed from the distilled amount of water that the esterification reaction rate reached 98% 10 minutes after addition. The melting point of the polymer obtained by polycondensing this esterification reaction product in the same manner as in Example 1 was 247°C.

Claims (1)

[Claims] 1 When producing a polyester containing 25 to 100 mol% of alkylene diphenyl-4,4'-dicarboxylate units, an aromatic dicarboxylic acid containing 0 to 100 mol% of diphenyl-4,4'-dicarboxylic acid or An esterification reaction product and/or a transesterification reaction product consisting of the ester-forming derivative and alkylene glycol are pre-existing in an amount of 25% by weight or more based on the diphenyl-4,4'-dicarboxylic acid supplied below. Diphenyl-4,4'-dicarboxylic acid or a mixture of diphenyl-4,4'-dicarboxylic acid and the remaining aromatic dicarboxylic acid and alkylene glycol are separately or continuously or intermittently supplied to the resulting system for esterification. A method for producing polyester, which comprises carrying out a reaction and then polycondensing the esterification reaction product.