JPS63245435A - Production of aromatic polyester - Google Patents

Abstract

PURPOSE:To obtain an aromatic polyester having an excellent heat resistance and a high degree of polymerization, by polycondensing a carboxylic acid component in which part of the carboxyl groups are converted into acid anhydride groups with an aromatic diol component in which part of the hydroxyl groups are converted into lower fatty acid ester groups. CONSTITUTION:An aromatic dicarboxylic acid and/or an aromatic hydroxycarboxylic acid (A) are reacted with 0.1-3.0 equivalent per equivalent of the carboxyl groups, of a lower fatty acid anhydride (e.g., acetic anhydride) at 100-160 deg.C for 1-8hr to convert at least part of the carboxyl groups into acid anhydride groups. An aromatic diol (B) is reacted with a lower fatty acid anhydride to convert at least part of the hydroxyl groups into lower fatty acid ester groups so that the number of moles of the free hydroxyl groups may be smaller than that of said anhydride groups. Component A and component B are reached with each other at normal pressure and 200-350 deg.C for 1-8hr, and after gradually decreasing the pressure, the reaction mixture is polycondensed at 280-350 deg.C in a high vacuum <=1Torr for 1-5hr to obtain an aromatic polyester of a number-average degree of polymerization >=50.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing aromatic polyester with a high degree of polymerization in a short time.

(Prior Art) Aromatic polyesters have been well known as heat-resistant polymers.

As a method for producing an aromatic polyester, an aromatic diol is made into a diacetate and reacted with an aromatic dicarboxylic acid. The so-called diacetate method is well known.

However, in this method, in order to obtain polyester with a high degree of polymerization sufficient for molding, it is necessary to carry out the reaction at a high temperature of 300°C or higher for a long time, and side reactions such as thermal decomposition reactions occur. As a result, there was a problem in that the polyester was colored yellow or gelled, making it impossible to obtain a high-quality polyester.

(Problems to be Solved by the Invention) The present invention provides an aromatic dicarboxylic acid, an aromatic diol and/or
Or high quality aromatic hydroxycarboxylic acid as l,
The purpose of this invention is to provide a method for producing aromatic polyester with excellent heat resistance in a short time.

(Means for Solving the Problems) In order to achieve the above object, the present inventors have conducted extensive research and found that if a raw material and an acid anhydride of a lower fatty acid are reacted and then a polycondensation reaction is performed, The present invention was achieved by discovering that the reaction time can be significantly shortened.

That is, the gist of the present invention is as follows.

When producing an aromatic polyester from an aromatic dicarboxylic acid and an aromatic diol and/or an aromatic hydroxycarboxylic acid, the carboxylic acid is reacted with an acid anhydride of a lower fatty acid to convert at least a portion of the carboxyl groups into acid anhydride groups. On the other hand, by reacting the aromatic diol with an acid anhydride of a lower fatty acid, at least a portion of the hydroxyl groups are converted to lower fatty acid ester groups, and the number of moles of free hydroxyl groups is equal to or less than the number of moles of the acid anhydride group. 1. A method for producing an aromatic polyester, which comprises carrying out a 9-polycondensation reaction.

In the present invention, it is necessary to convert at least a portion of the carboxyl groups of the carboxylic acid into acid anhydride groups and to convert at least a portion of the hydroxyl groups of the aromatic diol into lower fatty acid ester groups, followed by a single polycondensation reaction. . At this time, it is necessary to make sure that the number of moles of free hydroxyl groups is less than the number of moles of acid anhydride groups. Low phenolic hydroxyl method remains.

It is not possible to obtain a polyester with a high degree of polymerization of about 50 or higher, which can be used for practical purposes.

Specific examples of aromatic dicarboxylic acids in the present invention include:
Terefucuric acid (TPA), isophthalic acid ([P8).

4.4'-dicarboxydiphenyl, bis(4-carboxyphenyl)methane, bis(4-carboxyphenyl)sulfone, bis(4-carboxyphenyl)ether, 2.2-bis(2'-carboxyphenyl)propane, Examples include 2,6-naphthalene dicarboxylic acid, and these may be used in combination. Particularly preferred are TPA and rPA.

Further, specific examples of aromatic diols include hydroquinone, resorcinol, 4-dihydroxynaphthalene, 1
．． 5-dihydrokidinaphthalene, 1,6-cyhydroxynaphthalene, 2,6-cyhydroxynaphthalene, 2.2
'-dihydroxydiphenyl, 4゜4'-dihydroxydiphenyl, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl) sulfone, bis(4-hydroxyphenyl)ketone, bis(4-hydroxyphenyl)methane, 2 , 2-bis(4'-hydroxyphenyl)propane (bisphenol A), and derivatives of hydroquinone or naphthoquinone represented by the following formulas (a) to (dl), which may be used in combination.

In addition, specific examples of aromatic hydroxycarboxylic acids include:
4-Hydroxybenzoic acid, 4-hydroxy-3-methylbenzoic acid, 4-hydroxy-3-chlorobenzoic acid, 3-
Phenyl-4-hydroxybenzoic acid, 1-hydroxy-
Examples include 4-naphthoic acid and 2-hydroxy-6-naphthoic acid, and these may be used in combination.

Next, the acid anhydrides of lower fatty acids in the present invention include:
Acetic anhydride, propionic anhydride, butyric anhydride.

Isobutyric anhydride, valeric anhydride, pivalic anhydride, monochloroacetic anhydride, dichloroacetic anhydride, trichloroacetic anhydride, monobromoacetic anhydride, dibromoacetic anhydride, tribromoacetic anhydride, monofluoroacetic anhydride.

Examples include difluoroacetic anhydride and trifluoroacetic anhydride, but acetic anhydride is most preferred in terms of boiling point and price.

In the present invention, first, an aromatic dicarboxylic acid and/or an aromatic hydroxycarboxylic acid is reacted with an acid anhydride of a lower fatty acid to convert at least a part of the carboxyl group into an acid anhydride group. 0.1-3.0
Use double equivalents of acid anhydride. However, when an aromatic hydroxycarboxylic acid is used, it is desirable to add an acid anhydride in an amount other than this amount in an amount approximately equivalent to the hydroxyl group of the aromatic hydroxycarboxylic acid.

This reaction is carried out under normal pressure at a temperature below the boiling point of the acid anhydride, usually at 100 to 160°C for 1 to 8 hours, preferably at 140°C.
This can be done by heating at ~160°C for 2 to 5 hours.

On the other hand, an aromatic diol is reacted with an acid anhydride.

At least a portion of the hydroxyl groups are lower fatty acid ester groups, and the number of moles of free hydroxyl groups is 1.

The number of moles of the acid anhydride group formed by the reaction between the carboxylic acid and the acid anhydride is set to be less than or equal to the number of moles. Usually, the aromatic diol is subjected to the polycondensation reaction so that all hydroxyl groups become lower fatty acid ester groups.

The amount of acid anhydride groups produced by the reaction between carboxylic acid and acid anhydride is calculated from the absorbance ratio of the absorption caused by each carbonyl group of carboxyl acid anhydride groups in the infrared absorption spectrum of the reactant. be able to.

In this way, the aromatic dicarboxylic acid component reacted with the acid anhydride and the aromatic diol component and/or the aromatic hydroxycarboxylic acid component are subjected to a polycondensation reaction.

The aromatic dicarboxylic acid component and the aromatic diol component need to be charged in a substantially equimolar ratio, and unless this condition is satisfied, a polyester with a high degree of polymerization cannot be obtained.

In the polycondensation reaction, an aromatic dicarboxylic acid component, an aromatic diol component, and/or an aromatic hydroxycarboxylic acid component are charged into a polycondensation reactor, and the mixture is heated at 200 to 350°C under normal pressure for 1
After reacting for ~8 hours, preferably 2-5 hours at 260-280°C, gradually reduce the pressure and heat at 280-350°C for 1-5 hours under a high vacuum of 1 Torr or less. This is done by

In the method of the present invention, a single polycondensation reaction catalyst is not necessarily required, but a polycondensation reaction catalyst may be used to further promote the single reaction.

As the polycondensation reaction catalyst, one or more compounds selected from various metal compounds and organic sulfonic acid compounds can be used.

As the metal compound, compounds such as antimony, titanium, germanium, tin, zinc, aluminum, magnesium, calcium, monosodium potassium, manganese, or cobalt are used.

Examples of organic sulfonic acid compounds include sulfosalicylic acid, 0
- Compounds such as sulfobenzoic anhydride are used;
Dimethyltin maleate and O-sulfobenzoic anhydride are particularly preferably used.

The amount of the catalyst added is usually o, i x io-' to 100 X 10-' mol, preferably 0.5X10-' to 50X10-' mol, optimally l 10XIO-' moles are suitable.

(Example) Next, the three present inventions will be explained in more detail by giving examples.

Note that the method of measuring characteristic values, etc. is as follows.

Using Kudama Okunori gel permeation chromatography (HL C801 Model 8 manufactured by Toyo Soda Co., Ltd.), crossform containing 2.5% by volume of hexafluoroisopropanol was used as a solvent at a temperature of 39°C. It was determined by dividing the measured number average molecular weight by the molecular weight of the repeating unit.

Kinai differential scanning calorimeter (PerkinElmer DSC-2 model)
The measurement was carried out using a thermometer at a temperature rate of 20" for 67 minutes.

Using a comb flow tester (CFT-500 model manufactured by Shimabara Seisakusho), with a diameter of 0.5 mm, length of 2 mm,
The load is 100kg/c, I, and the initial temperature is 200℃.
The temperature was further increased at a rate of 10°C/sin, and the temperature was determined as the temperature at which the polymer began to flow out from the goo.

Example 1 A reactor was charged with TPA and acetic anhydride (AczO) at an equivalent ratio of 1:1, and 2
Mix for 9 hours and then gradually reduce the pressure to 1 torr.

The reaction was carried out at 150°C for 2 hours to obtain white crystals.

This white crystal has an infrared absorption spectrum of 1730 cm-' and 1780 cm-' as shown in Figure 1.
It was confirmed that at least a part of the carboxyl groups had been converted to acid anhydride groups.

On the other hand, the hydroquinone derivative of the formula (al) and Ac, 0
were reacted with each other to form a diacetate.

To the reaction product of TPA and Ac20, diacetate of the above hydroquinone 331 in an equimolar amount as TPA was added, and 280
The reaction was carried out at ℃ for 2 hours. Then, gradually reduce the pressure and increase the temperature.
Finally, the reaction was carried out at 1 Torr and 320° C. for 2 hours.

The obtained polyester had an average degree of polymerization of 98. Melting point 402
It was a good crystalline polyester with one color tone at ℃.

The infrared absorption spectrum of this polyester is shown in FIG.

In addition, 1 This polyester did not show absorption of hydrogen atoms of methyl groups based on acetate ester (1.5 pprrl and 2.3 ppm) in the 'H-NMR spectrum.

Furthermore, the result of elemental analysis of this polyester is C=76
．． 2% (theoretical value 77.6%) + H = 4.88% (theoretical value 5.06%).

Examples 2 to 5 and Comparative Example 1 Polyester was obtained in the same manner as in Example 1, except that the equivalent ratio of TPA and Ac20 when reacting them was changed as shown in Table 1. Ta.

Table 1 shows the number average degree of polymerization of the obtained polyester.

Table 1 Examples 6 to 18 Example 1 except that the aromatic dicarboxylic acid, aromatic diol, and acid anhydride of lower fatty acid were changed to those shown in Table 2.
Polyester was produced in the same manner.

Table 2 shows the number average degree of polymerization of the obtained polyester.

Table 2 91 DOD: To 4.4'-dihydroxydiphenyl B: Bisphenol A Example 19 In a reactor, TPA, 4-hydroxybenzoic acid and Ac,
0 at an equivalent ratio of 1:3:5 under a nitrogen atmosphere.

The mixture was mixed at normal pressure and 150°C for 2 hours, then gradually reduced in pressure, and finally reacted at 1 torr and 150°C for 2 hours.

White crystals were obtained.

To this reaction mixture was added diacetate of the hydroquinone derivative of the formula (al) in an equimolar amount to TPA, and the mixture was heated at 1280°C for 2 hours.
Allowed time to react. Then, the pressure was gradually reduced and the temperature was increased, and the reaction was finally carried out at 1 torr and 320°C for 2 hours.

The obtained polyester had an average degree of polymerization of 123. It was a good thermotropic liquid crystalline copolyester with a flow initiation temperature of 278° C. and one color tone.

The infrared absorption spectrum of this copolyester is shown in FIG.

Moreover, this copolyester did not show absorption of hydrogen atoms of methyl groups based on acetate ester (1.5 ppm and 2.3 ppm) in the 'H-NMR spectrum.

Furthermore, the results of elemental analysis of this copolyester show that
C=70.1% (theoretical value 69.3%), Fl=3.
It was 28% (theoretical value 3.34%).

(Effects of the Invention) According to the present invention, there is provided a method for economically producing aromatic polyester with good color tone and excellent heat resistance from aromatic dicarboxylic acid, aromatic diol, and/or aromatic hydroxycarboxylic acid. be done.

[Brief explanation of drawings]

Figure 1 shows the infrared absorption spectrum of the reaction product of terephthalic acid and acetic anhydride in Example 1, Figure 2 shows the infrared absorption spectrum of the polyester obtained in Example 1, and Figure 3 shows the infrared absorption spectrum of the polyester obtained in Example 19. FIG. 3 is a diagram showing an infrared absorption spectrum of a copolyester.

Claims (1)

[Claims] (1) When producing an aromatic polyester from an aromatic dicarboxylic acid, an aromatic diol, and/or an aromatic hydroxycarboxylic acid, the carboxylic acid is reacted with an acid anhydride of a lower fatty acid to convert at least a portion of the carboxyl group into an acid. On the other hand, by reacting an aromatic diol with an acid anhydride of a lower fatty acid, at least a part of the hydroxyl group becomes a lower fatty acid ester group, and the number of moles of the free hydroxyl group is the number of moles of the acid anhydride group. A method for producing an aromatic polyester, which comprises carrying out a polycondensation reaction after performing the following steps.