KR920010522B1 - Process for preparing aromatic polyester - Google Patents

Abstract

The polyester is produced by polymerizing an aromatic dicarboxylic acid and/or its functional deriv. (A), an aromatic oxycarboxylic acid and/or its functional deriv. (B) and a dihydroxy aromatic cpd. and/or its functional deriv. (C) in the presence of 0.01-2 wt.% phosphorus cpd. of formula (D) [R1=R2=R3=H, C1-4 alkyl or phenyl w.r.t. the produced polymer. The mole ratio of (A), (B) and (C) satisfies an equation of 0.9 [A / [C < 1.1 and 0.1 [A /[B 1.0. (A) is pref. terephthalic acid or isophthalic acid, (B) is pref. p- hydroxy denzoic acid, (C) is pref. hydroquinone or bisphenol A, and (D) is pref. triphenyl phosphate. The polyester has a low coloring rate and a good melting stability.

Description

Method for producing aromatic polyester

The present invention relates to a method for producing a new aromatic polyester, and more particularly, to a method for producing an aromatic polyester having a low coloration rate and excellent melt stability.

In general, all aromatic polyesters are excellent in various physical properties, in particular, extremely excellent in heat resistance. Among them, all aromatic polyesters made of terephthalic acid and / or isophthalic acid, p-hydroxybenzoic acid or derivatives thereof and dihydroxy aromatic compounds can be injection molded, and various physical properties, that is, mechanical properties, electrical properties, thermal stability, etc. At the same time, it has excellent performances such as high heat resistance, chemical resistance, oil resistance, radiation resistance, and numerical stability, and is widely used in machinery parts, electrical and electronic parts, and automotive parts.

However, these wholly aromatic polyesters tend to retain reactive -COOH groups at their ends, have a high coloring ratio, and inferior to melt stability, such as high molecular weight due to high molecular weight of the polymer during melt molding. Since it has, the development of the aromatic polyester with low coloring rate and excellent melt stability has been desired.

Therefore, the present inventors have conducted extensive research on the composition capable of producing aromatic polyesters with low coloration rate and excellent melt stability. As a result, the inventors have identified specific aromatic dicarboxylic acids, aromatic oxycarboxylic acids, and dihydroxy aromatic compounds. The present invention has been completed based on the fact that the above object can be achieved by preparing an aromatic polyester using a specific phosphorus compound as a composition ratio.

More specifically, the present invention provides an aromatic dicarboxylic acid, a functional derivative thereof or a mixture (A) of two or more thereof; Aromatic oxycarboxylic acids, functional derivatives thereof or mixtures of two or more thereof (B); And in the polymerization of a dihydroxy aromatic compound, a functional derivative thereof or a mixture of two or more thereof (C) to produce an aromatic polyester, the molar ratio of each component (A), (B), (C) is represented by the following formula Meet (I) and (II),

A phosphorus compound of the following general formula (D) is a method for producing an aromatic polyester, characterized in that the polymerization is carried out in an amount present in an amount of 0.01-2% by weight of the amount of the final polymer.

(Wherein R ₁ , R ₂ and R ₃ each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenyl group)

In the present invention, specific examples of the aromatic dicarboxylic acid or derivative (A) usable include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, methyl-terephthalic acid, methyl-isophthalic acid and these Alkyl esters, aryl esters, ie, terephthalic acid dimethyl (dmethyl terphthalate), terephthalic acid diphenyl, isophthalic acid dimethyl, isophthalic acid diphenyl, and the like. The derivatives are terephthalic acid diphenyl and isophthalic acid diphenyl.

In addition, specific examples of the aromatic oxycarboxylic acid or derivative (B) usable in the present invention include p-hydroxy benzoic acid, p-hydroxy benzoic acid phenyl, p-acetoxy benzoic acid, and the like. Benzoic acid is most preferred.

Moreover, as a specific example of the dihydroxy aromatic compound or its derivative (C) which can be used in this invention, hydroquinone, resorcinol, bisphenol A, naphthalene diol, dihydroxy biphenyl, these alkyl esters, an aryl ester, etc. Among them, hydroquinone and bisphenol A are most preferred.

Said component (A), (B), and (C) may be used independently, respectively, or may mix and use 2 or more types of these.

For example, as the component (A), terephthalic acid may be used alone, or a mixture of isophthalic acid and terephthalic acid may be used depending on the intended purpose.

In the present invention, specific examples of the phosphorus compound that can be used include phosphoric acid, trimethyl phosphate, dimethyl phosphate, triphenyl phosphate, diphenyl phosphate, and the like, of which triphenyl phosphate is most preferred.

In addition, the usage-amount of each said component (A), (B), (C) and (D) must satisfy the said limited range. When the molar ratio of component (A) and component (C) does not satisfy formula (I), the degree of polymerization is low, which is not preferable, and the molar ratio of component (A) and component (B) does not satisfy formula (II). It is not preferable because the softening point of the polymer obtained as a result is high and melt molding is difficult. When the amount of the phosphorus compound (D) is less than 0.01% by weight of the final amount of the polymer produced, the effects of the present invention, such as color improvement and melt stability, do not appear. The polymerization reaction time is delayed, which causes various undesirable practical problems.

The reaction is carried out in a molten state by combining a certain amount of the above components (A), (B), (C) and (D) within the above defined ranges.

If necessary, the solid phase polymerization may be performed after the reaction. The reaction temperature is preferably 300-400 ° C. The reaction pressure is not particularly limited, but it is usually preferred to reduce the pressure as the reaction proceeds.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples described below.

In the following Examples and Table 1, the color and melt stability were measured by the following method.

* Color: L, a, b measurement using a color measuring instrument, C.C.M (abbreviation of Computer Color Matching as a trade name) manufactured by I.C.S.Model No. MM-8000

* Melt Stability: When spinning the polymer using a melt spinning machine, the number of cuts occurred and the pack pressure were determined based on the following criteria.

Good: Number of rounds-less than once per hour

Pack pressure rise-less than 10kg / cm ²

Poor: Number of cuts-more than once per hour

Pack pressure rise-10kg / cm ² or more

Example 1

82.8 g (0.6 mol) of stainless reaction tube p-hydroxy benzoic acid with a stirrer, nitrogen inlet and outlet, 24.9 g (0.15 mol) of terephthalic acid, 24.9 g (0.15 mol) of isophthalic acid. 17.6 g (0.16 mole) of hydroquinone and 34.2 g (0.15 mole) of bisphenol A were added, followed by sufficient nitrogen filling and heating to 250 ° C. over 3 hours.

Next, 0.474 g of triphenyl phosphate was added thereto, and the mixture was allowed to react for 2 hours under reduced pressure while increasing the temperature inside the tube to 340 ° C over 1 hour. The color of the resulting polymer was measured and dried, spun through a nozzle of 0.5 mm in diameter at 350 ° C. using a melt spinner, and then wound at a speed of 200 m / min. At this time, the melt spinning state of the polymer had no cutting and the pack pressure was uniform. The results are presented in Table 1.

Comparative Example 1

The same procedure as in Example 1 was carried out except that triphenyl phosphate was not used in Example 1. The color of the polymer obtained as a result was higher in coloration rate than the polymer obtained in Example 1, and the melt spinning state was poor, such as an increase in pack pressure and generation of cuts over time. The results are shown in Table 1.

Example 2

In Example 1, 124.2 g (0.9 mol) of p-hydroxy benzoic acid, 49.8 g (0.3 mol) of isophthalic acid, 17.6 g (0.16 mol) of hydroquinone, and 34.2 g (0.15 mol) of bisphenol A were used. As in Example 1, except that 0.503 g of triphenol phosphate was used. Similar to Example 1, a good polymer was obtained. The results are shown in Table 1.

Comparative Example 2

The same procedure as in Example 1 was performed except that triphenyl phosphate was not used in the composition of Example 2. As a result, the melt-spun state became unstable over time similarly to Comparative Example 1. The results are shown in Table 1.

TABLE 1

As can be clearly seen from Table 1, the aromatic polyesters obtained from Examples 1 and 2 according to the present invention have a significantly lower coloration rate and excellent melt stability compared to the conventional ones, which is a defect of the conventional aromatic polyesters. The defects such as high rate and high polymer molecular weight during melt molding increase the melt viscosity.

Claims (3)

Aromatic dicarboxylic acids, functional derivatives thereof or mixtures of two or more thereof (A); Aromatic oxycarboxylic acids, functional derivatives thereof or mixtures of two or more thereof (B); And in the polymerization of a dihydroxy aromatic compound, a functional derivative thereof or a mixture (C) of two or more thereof to produce an aromatic polyester, the molar ratios of the components (A), (B) and (C) are represented by the following formulas. Meet (I) and (II),

A process for producing an aromatic polyester, wherein the phosphorus compound of the following general formula (D) is polymerized in the state of being present in an amount of 0.01-2% by weight of the final amount of polymer.

(Wherein R ₁ , R ₂ and R ₃ each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenyl group) The terephthalic acid or isophthalic acid of the aromatic dicarboxylic acid (A), the aromatic oxycarboxylic acid (B) is p-hydroxy benzoic acid, and the dihydroxy aromatic compound (C) is hydroquinone or bisphenol. A method for producing an aromatic polyester, characterized in that. The method for producing an aromatic polyester according to claim 1 or 2, wherein the phosphorus compound (D) is triphenyl phosphate.