JPH01161015A - Manufacture of polyester - Google Patents

Abstract

PURPOSE:To produce a polyester excellent in heat resistance, by adding a low- molecular weight monocarboxylic acid to an initial reaction system of a specific aromatic hydroxycarboxylic acid, a polyester, a diol, a dicarboxylic acid, and acetic anhydride, and reacting them. CONSTITUTION:An aromatic hydroxycarboxylic acid of formula I (e.g., p- hydroxybenzoic acid), a polyester of formula II of a condensate obtained from an aromatic dicarboxylic acid and an alkylene glycol (e.g., polyethylene terephthalate), an aromatic diol of formula III (e.g., 4,4'-dihydroxybiphenyl), an aromatic dicarboxylic acid of formula IV (wherein Ar1-Ar4 are each a divalent aromatic group; and R1 is divalent alkylene) (e.g., terephthalic acid), acetic anhydride, and a low-molecular weight monocarboxylic acid (e.g., acetic acid) are mixed and heated to produce a polyester. The lowering of the molecular weight of the resulting polyester by heat treatment is small.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a method for producing polyester that can be synthesized only by melt polymerization, uses low-cost raw materials, and has good heat resistance with little molecular weight reduction due to heat treatment. It is related to.

<Prior art> A copolymerized polyester consisting of a polyester unit produced from an aromatic hydroxycarboxylic acid, a polyester unit produced from an aromatic diol and an aromatic dicarboxylic acid, and a polyester unit produced from an alkylene glycol and an aromatic dicarboxylic acid is disclosed in Japanese Patent Publication No. It is disclosed in Japanese Patent Application Laid-Open No. 58-84821, etc.

JP-A-51-8395 and JP-A-58-848
The copolymerized polyester disclosed in Publication No. 21 includes a, an acetylated product of an aromatic hydroxycarboxylic acid, b, an acetylated product of a polyester obtained by condensing an aromatic dicarboxylic acid and an alkylene glycol, and a C2 aromatic diol, and d.
It is described that it is produced by a method consisting of a first step of charging and condensing an aromatic dicarboxylic acid, and a second step of reducing the pressure of the reaction system to obtain a high molecular weight.

Furthermore, JP-A-62-41220 discloses (i) an aromatic hydroxycarboxylic acid, (if) a polyester formed by condensing an aromatic dicarboxylic acid and an alkylene glycol;
iii) ai < After reacting (it) with (i) using a small amount of aromatic diol and (iv) acetic anhydride, (i)
A method for producing a copolymerized polyester is disclosed that requires acetylation by step v). -〈Problems to be solved by the invention〉 However, in the production methods described in JP-A-51-8395 and JP-A-58-84821, the aromatic hydroxycarboxylic acid and the aromatic diol are prepared in advance. Also, it is necessary to induce the acetylated product in a separate process, and the polymer cannot be obtained at low cost. Unexamined Japanese Patent Publication 1986-
In the production method described in Publication No. 44220, (1) aromatic dicarboxylic acid is not copolymerized, resulting in a polymer with low heat resistance and insufficient molecular weight; and (iv)
Since acetic anhydride is added later, it is necessary to cool the reaction system midway through, which makes the reaction time long and the reaction complicated.

An object of the present invention is to use non-acetylated monomers and to produce a copolymerized polyester that has good heat resistance and high mechanical properties, such as a small decrease in molecular weight due to heat treatment.

Means for Solving the Problems> That is, the present invention condenses (1) aromatic hydroxycarboxylic acid represented by the following formula (I), (2) aromatic dicarboxylic acid represented by the following structural unit (II), and alkylene glycol. When producing a polyester by reacting an aromatic diol represented by the following formula (I[I), an aromatic dicarboxylic acid represented by the following formula (TV), and an acetic anhydride, the initial reaction system This is a method for producing polyester, which involves adding a low molecular weight monocarboxylic acid to the polyester.

HO-Ar1-COOH・・・・・・(■)(0-R1
-02C-Ar4-CO) (II) HQ-Ar2-
OH・Old・(■) HCOO-Ar3-cooH・Old・・(1v)(Ar1
~Ar4 is a divalent aromatic group, R1 is a divalent alkylene group, and Ar1 to Ar4 may be the same or different from each other. ) The polyester produced in the present invention is produced using the above-mentioned materials 1 to 2 as raw materials. In the above formula, A r1~A
r and 4 are divalent aromatic groups, which may be the same or different from each other, and may be mixed. is preferred.

Furthermore, preferably used A r 3 and A r 4
(X represents a hydrogen atom or a chlorine atom), and in both cases, the coexistence of a paraphenylene group or a paraphenylene group with another group is particularly preferred.

Further, R1 is a divalent alkylene group, especially (CH2
)2 is preferred.

The polyester produced in the present invention includes: (1) an aromatic hydroxycarboxylic acid, (2) a polyester obtained by condensing an aromatic dicarboxylic acid with an alkylene glycol, (2) a polyester obtained by reacting an aromatic diol, (1) an aromatic dicarboxylic acid, and (2) acetic anhydride. It is manufactured by adding a low molecular weight monocarboxylic acid to the initial reaction system for manufacturing.

■Aromatic hydroxycarboxylic acid and ■Aromatic diol■
The corresponding acetyl compound is formed through acylation with acetic anhydride, and the polyester formed by condensing aromatic dicarboxylic acid and alkylene glycol forms the corresponding polyester fragment through acid decomposition, and these and ■ aromatic dicarboxylic acid are Both react sequentially by deacetic acid reaction, and finally become high molecular weight polymers.

In the production method of the present invention, the raw materials (■) to (■) are usually ■,
■ is in the range of 5 to 95 mol%, ■ is in the range of 5 to 95 mol%, ■ is in the range of 5 to 95 mol%, and ■ is in the range of 0.7 to 1.3 with respect to the total of 100 mol% of ■ and ■. It is preferably charged within the molar amount range.

From the point of view of the heat resistance of the polyester to be manufactured, in particular,
For the total 100 mol% of and ■, [■±■ is 77
~95 mol%, ■ is in the range of 5 to 23 mol%, ■/■ molar ratio is in the range of 75/25 to 9515, ■ is 0 relative to ■
．． It is preferably charged in a range of 9 to 1.1 moles.

However, ■ is characterized by the average of repeating units. In particular, when ■ is polyethylene terephthalate, molecule 1 is 192.
It is preferable to convert as 17.

In addition, acetic anhydride has 1
．． Preferably, 0 to 1.5 times the mole is used, and 1.05 to 1.2 times the mole.

A feature of the present invention is that in addition to the above raw materials (1) to (4), a low molecular weight monocarboxylic acid is added to the initial reaction system.

The low molecular weight monocarboxylic acid used in the production method of the present invention is
Generally, it is a compound having 1 to 10 carbon atoms and one carboxyl group in its chemical structure. Examples include formic acid, acetic acid, propionic acid, and carbolic acid, but acetic acid is preferred because it is easily available.

In the method of the present invention, it is preferable to add the low molecular weight monocarboxylic acid and acetic anhydride in a molar ratio of 0.01 to 2:1, particularly 0.03 to 1:1. is preferable.

In the production method of the present invention, by adding the above-mentioned low molecular weight monocarboxylic acid to the initial reaction system, the thermal stability during heating of the polymer is improved, and the initial reaction proceeds more quickly.

Although the reason is not clear, it is thought to be as follows.

When the hydroxyl groups of ■ and ■ react with acetic anhydride to form an acetyl compound, the low molecular weight monocarboxylic acid acts as an acid catalyst and accelerates the reaction. Furthermore, excess acetic anhydride reacts with the aromatic dicarboxylic acid to form an acid anhydride bond, and by repeating the acid anhydride exchange reaction, it is thought that an acid anhydride bond is formed in the polymer core. However, it is considered that the presence of a low molecular weight monocarboxylic acid in the reaction system can reduce the reaction between acetic anhydride and aromatic dicarboxylic acid.

In the present invention, there are no particular limitations other than adding a low molecular weight monocarboxylic acid to the initial reaction system.
and low molecular weight monocarboxylic acids, it is preferable that at least ■, ■, ■, and low molecular weight monocarboxylic acids are present in the initial reaction system. In this case, even if ■ and ■ are present in the initial reaction system, Good, the reaction takes a certain stage,
Preferably, the reaction temperature is 150°C or higher and 290°C or higher, respectively.
By adding (■) later, which may be added at the stage below 'C', the polyester aggregates 'a' and becomes impossible to stir, which is a process disadvantage that tends to occur during large-scale polymerization, especially when a large amount of reaction is carried out. can be avoided. Also,
By adding (2) later, the compound that causes acid anhydride bonds to form in the polymer chain loses the opportunity to react, which has the advantage of improving the thermal stability of the resulting polymer during heating.

A preferred method of the present invention is shown below.

(a) ■~■ and a low molecular weight monocarboxylic acid are charged into a reaction vessel, and heated to 80~300°C, preferably 100°C under a nitrogen stream.
Carry out the acetylation reaction at a temperature between 250 °C and 250 °C.
The polymer is obtained by polymerization under vacuum at a temperature between 290°C and 320°C, preferably between 290°C and 320°C.

(b) Charge ■~■, ■ and a low molecular weight monocarboxylic acid into a reaction vessel, and perform the acetylation reaction at 80~300°C, preferably 100~250''C under a nitrogen stream. °C, preferably 180-290 °C
and then further added at 250 to 330°C, preferably 2
The polymer is obtained by polymerization under vacuum at 90-320°C.

(c) ■, ■~■ and low molecular weight monocarboxylic acids are charged into a reaction vessel, and an acetylation reaction is carried out at 80~300°C, preferably 100~250°C under a nitrogen stream. °C, preferably 200-250°
Post-add with C and further 4. : Polymerization is carried out under vacuum at 250-330°C, preferably 290-320°C to obtain a polymer.

(d) Charge ■, ■, ■ and a low molecular weight monocarboxylic acid into a reaction vessel, and perform an acetylation reaction at 80 to 300'C5 preferably 100 to 250°C under a nitrogen stream, then,
(1) at 150-300°C, preferably 180-290°C, and (2) at 150-300°C, preferably 200-290°C.
Post-added simultaneously or separately at 50°C, and further added at 250°C to
The polymer is obtained by polymerization under vacuum at 330°C, preferably 290-320°C.

In addition, in the production method of the present invention, although the reaction proceeds even without a catalyst, stannous acetate, zinc acetate, antimony acetate,
In some cases, it may be preferable to add metal compounds such as antimony trioxide, tetrabutyl titanate, sodium acetate, potassium acetate, metallic magnesium, and the like.

Moreover, the melt viscosity of the copolymerized polyester of the present invention is 10 to
15,000 boiz is preferred, especially 20-5,000
Boise is more preferred.

Note that this melt viscosity is a value measured using a Koka type flow tester under the conditions of liquid crystal initiation temperature +40''C) and a slip rate of 1,000 (1/sec). The viscosity is (0゜1g/dj concentration, 60
can be measured in pentafluorophenol at
0.5-5 d j /g is preferable, 1.0-3.
Particularly preferred is 0 dj/g.

In addition, in the production method of the present invention, in addition to the polyester raw materials (1) to (2) above, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid, alicyclic carboxylic acids such as hexahydroterephthalic acid, 1.4
- Further polymerization of aliphatic and alicyclic diols such as butanediol, 1,6-hexanediol, neopentyl glycol, and 1,4-cyclohexane dimetatool in a small proportion that does not impair the purpose of the present invention. You can force it.

The manufacturing method of the present invention can obtain a polyester with a high degree of polymerization only by melt polymerization, and the polyester has good optical anisotropy, mechanical properties, and can be subjected to ordinary melt molding such as compression molding and blow molding. It can be processed into fibers, films, three-dimensional molded products, containers, hoses, etc.

In addition, the strength of the molded article obtained in this manner can be increased by heat treatment, and the elastic modulus may also be increased. This heat treatment can be carried out by heat treating the molded article in an inert atmosphere (eg nitrogen, argon, helium or water vapor) or in an oxygen-containing atmosphere (eg air) at a temperature below the melting point of the polymer. This heat treatment may or may not be under tension, and can be carried out for several tens of minutes to several days.

Addition of reinforcing materials such as glass fibers, carbon fibers, and asbestos, fillers, nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants, mold release agents, and flame retardants to the polyester produced by the present invention. Agents and other thermoplastics can be added to impart desired properties.

<Example> The present invention will be further explained below with reference to Examples.

Example 1 p-hydroxyammonium was added to a polymerization test tube equipped with a stirring device.
6 acid 51.79g <0.375 mol), 4゜4-di-doxybiphenyl 9.31g <0゜05 mol),
Polyethylene terephthalate 14 with an intrinsic viscosity of about 0.6
．． 41g <0.075 mol), acetic anhydride 53.34g
(0,522 mol) and acetic acid 2.4 g (0,04
mol) and reacted at 150°C for 1.5 hours.

The wettability and slurry properties of the reaction system were better than when acetic acid was not added, indicating that acetic acid was working as a catalyst. Thereafter, the temperature was raised at a rate of 50°C per hour until it reached 300°C, and a small amount of associated material thought to be caused by terephthalic acid was observed at around 250°C.

The pressure was reduced to 0.5 gmHg at 300° C. over 1 hour, and polymerization was further carried out for 1 hour to complete the reaction.

In the resulting polymer pentafluorophenol, 0.1
g/dj concentration, logarithmic viscosity at 60°C is 1°85 dJ
/Iz. This polymer was heated in an oven at 150℃ for 1
After 20 hours of heat treatment, the logarithmic viscosity was 1.7.
8 dj/g, and the decrease in viscosity was as small as 0.07 dj/g. The theoretical structural formula of this polymer is shown by the following formula.

J/m, /n=75/10/15 Example 2 The same procedure as Example 1 was carried out except that the amount of acetic acid was changed to 4=8 g (0.08 mol). Logarithmic viscosity before heat treatment is 1
．． 90 dll/g, and 1°84 dj/g after heat treatment
and the viscosity decrease is 0.06d, I! /g.

Comparative Example 1 The same procedure as Example 1 was carried out except that acetic acid was not added. The distillation rate of acetic acid was slower than that in Example 1, and a large amount of associated substances observed at around 250°C were believed to be caused by terephthalic acid. The logarithmic viscosity of the obtained polymer before heat treatment was 1.85 dj/+r, and after heat treatment it was 1.69 dj/, with a viscosity decrease of 0.
．． 16d''/7g, which was significantly larger than that of Example 1.2.

From the above results, it is clear that the polyester produced by the production method of the present invention can be obtained with less decrease in molecular weight due to heat treatment.

<Effects of the Invention> According to the production method of the present invention, it has become possible to produce polyester without going through complicated steps using a polymer with good heat resistance and raw materials that are extremely easy to obtain.

Claims (1)

[Claims] [1] An aromatic hydroxycarboxylic acid represented by the following formula (I), [2] an aromatic dicarboxylic acid represented by the following structural unit (II), and an alkylene glycol condensed together. When producing a polyester by reacting a polyester, [3] an aromatic diol represented by the following formula (III), [4] an aromatic dicarboxylic acid represented by the following formula (IV), and [5] acetic anhydride, the initial reaction A method for producing polyester, characterized by adding a low molecular weight monocarboxylic acid to the system. HO-Ar_1-COOH・・・・・・(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・(II) HO-Ar_2-OH・・・・・・(III) HCOO-Ar_3-COOH・...(IV) (Ar_1 to Ar_4 are divalent aromatic groups -R_1 is a divalent alkylene group, and Ar_1 to Ar_4 may be the same or different from each other.)