JP3057772B2 - Method for producing liquid crystalline copolyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a liquid crystalline polyester resin having a high strength and a high modulus of elasticity and, in particular, extremely excellent hydrolysis resistance. Low loss of linear expansion characteristics, fluidity, high strength, elastic modulus, without losing the heat resistance, relates to a method to dramatically improve the hydrolysis resistance,
Specifically, the present invention relates to a method for producing a liquid crystalline copolymerized polyester, which comprises using an antimony-based catalyst when melt-polymerizing the polyester.

[0002]

2. Description of the Related Art In general, a thermotropic liquid crystalline polyester resin (hereinafter, referred to as a liquid crystalline polyester) which forms an anisotropic molten phase has a low molding shrinkage, a good fluidity, and a low burr. Utilizing properties such as low generation, extremely high elastic modulus, low post-shrinkage of injection molded products, and good chemical resistance, the fields of electric and electronic materials, automobile materials, and sound Market development is progressing in the field of equipment and sports equipment. However, such a useful material, liquid crystal polyester,
Despite its drawback of poor hydrolysis resistance, its excellent properties have attracted attention in recent years, and despite being used in various fields such as the fields of electricity, electronic materials, and automotive materials. However, it has a problem that it is not used in a field where hydrolysis resistance occupies a large weight as a required performance.

[0003]

Various attempts have conventionally been made to improve the hydrolysis resistance.
For example, the hydrolysis resistance is correlated with the terminal carboxyl group of the polymer, and it has been known that the reduction of the terminal carboxyl group improves the hydrolysis resistance. Attempts have been made to add additives such as oxazoline compounds and epoxy compounds that react with groups. However, although these methods certainly improve the hydrolysis resistance, their effects were hardly satisfactory. Further, when these additives are added, the melt viscosity is increased, and the liquid crystal polyester has disadvantages such as impairment of good fluidity, which is a characteristic of liquid crystal polyester, and deterioration of heat resistance in general. The hydrolysis resistance can also be improved by selecting the type and composition of the monomer constituting the polymer. However. If a monomer that improves the hydrolysis resistance is selected, there is a problem that the fluidity is reduced.

[0004]

Means for Solving the Problems In producing a liquid crystal polyester having a specific monomer type and composition having good flowability, the present inventors have proposed a liquid crystal polyester by using a specific catalyst, that is, an antimony-based catalyst. It has been found that the hydrolysis resistance is drastically improved without losing the low linear expansion coefficient, fluidity, high strength, elastic modulus, and heat resistance, which are the features of the present invention, and arrived at the present invention. That is, the gist of the present invention is that the general formula (A) —CO—R ¹ —CO—O—R ² —O— (A) wherein R ¹ is a divalent aromatic hydrocarbon having 6 to 20 carbon atoms. A divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or /
And a divalent aliphatic hydrocarbon group having 1 to 40 carbon atoms (provided that the hydrogen atom in the aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl or alkoxy group having 1 to 4 carbon atoms) Wherein R ² is a divalent aliphatic hydrocarbon group having 2 to 40 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. A hydrogen group (however, a hydrogen atom of the aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl or alkoxy group having 1 to 4 carbon atoms), or a polyalkylene oxide divalent having a molecular weight of 80 to 8000 5-95 mol% raw oligoester in the amount of the repeating units consisting of repeating units represented by showing the radicals} and, the general formula ^{(B) HO-R 3 -COOH} (B) { wherein R ³ is The number of carbon atoms forming an aromatic ring is from 6 to 20 A divalent aromatic hydrocarbon group (however, a hydrogen atom of an aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl or alkoxy group having 1 to 4 carbon atoms)} A copolymer oligomer is prepared by reacting 95 to 5 mol% of an acid (first step), then acylation is performed by adding an acylating agent (second step), and polymerization is further performed under reduced pressure (third step). The present invention relates to a method for producing a liquid crystalline copolyester, which comprises using an antimony-based catalyst as a catalyst in a three-step reaction.

Hereinafter, the present invention will be described in detail. The present invention is carried out by reacting the oligoester represented by the general formula (A) with a hydroxycarboxylic acid to form a copolymer oligomer, acylating the copolymer, and then polymerizing under reduced pressure. In order to produce the oligoester represented by the general formula (A), a dicarboxylic acid represented by the general formula (C) and an ester thereof and a diol represented by the general formula (D) are used. HOOC-R ¹ —COOH (C) (wherein, R ¹ has the same meaning as in general formula (A).) HO—R ² —OH (D) (wherein, R ² has the same meaning as in general formula (A). .)

Examples of the dicarboxylic acid represented by the general formula (C) include terephthalic acid, methoxyterephthalic acid, ethoxyterephthalic acid, fluoroterephthalic acid, chloroterephthalic acid, methylterephthalic acid, isophthalic acid, phthalic acid and methoxyisophthalic acid. Acid, diphenylmethane-4,
4'-dicarboxylic acid, diphenylmethane-3,3'-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-1,5 -Dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, adipic acid, sebacic acid, azelaic acid, suberic acid, dodecanedicarboxylic acid, 3-methylazeline acid, glutaric acid, succinic acid, cyclohexane-1,4-dicarboxylic acid, Examples thereof include cyclohexane 1,3-dicarboxylic acid, cyclopentane 1,3-dicarboxylic acid and the like, and methyl esters and ethyl esters thereof. These may be used as a mixture, and any other compounds represented by the general formula (C) can be used. Of these, terephthalic acid is particularly preferably used.

Specific examples of the diol represented by the general formula (D) include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, and 1,4-butanediol. , Neopentyl glycol, 1,6-hexanediol, 1,12-dodecanediol, cyclohexane 1,4-diol, cyclohexane 1,3-diol, cyclohexane-1,2-
Examples thereof include diol, cyclopentane-1,3-diol, diethylene glycol, polyethylene glycol, hydroquinone, resorcinol, bisphenol-A, methylhydroquinone, chlorohydroquinone, and 2,6-naphthalenediol. Any of the other compounds represented by the general formula (D) can be used. Preferably, ethylene glycol or 1,4-butanediol is used.

The starting oligoester can be obtained by directly reacting the above-mentioned dicarboxylic acid with a diol, or can be produced by a transesterification method between the above-mentioned dicarboxylic acid ester and a diol. The latter transesterification method is preferred in order to substantially eliminate the presence of COOH groups in the starting oligoester. As the oligoester used in the present invention, any polyester or oligoester having a repeating unit represented by the general formula (A) can be used, but polyethylene terephthalate and polybutylene are used because of their availability. Terephthalate and its oligomers are preferred, and polyethylene terephthalate and its oligomers are particularly preferred.

The hydroxycarboxylic acids represented by the general formula (B) include parahydroxybenzoic acid, 4-hydroxy-3-chlorobenzoic acid, metahydroxybenzoic acid,
-Hydroxy-3,5-dimethylbenzoic acid, 2-oxy-6
-Naphthoic acid, 1-oxy-5-naphthoic acid, 1-hydroxy-4-naphthoic acid, shringer acid, vanillic acid,
4-hydroxy-3-methylbenzoic acid and the like.
Although it is preferable to use parahydroxybenzoic acid alone to maintain the melt anisotropy, any of the hydroxycarboxylic acids represented by the general formula (B) can be used, or a mixture of these can be used. It doesn't matter.

In the present invention, the charging ratio of the oligoester to the hydroxycarboxylic acid is as follows: oligoester: hydroxycarboxylic acid = 5 to 95:95 to 5 (mol%), preferably 5 to 70:95 to 30; More preferably, it is 5-60: 95-40. In the present invention, the reaction (first step) of reacting the above-described hydroxycarboxylic acid with the oligoester represented by the general formula (A) to form a copolymerized oligomer is performed at 200 to 350 ° C., preferably 220 to 350 ° C.
The reaction is carried out at a temperature ranging from 5 minutes to 10 hours, preferably from 20 minutes to 5 hours. In the reaction, the residual amount of the oxycarboxylic acid compound was 70 mol% based on the charged amount.
Or less, preferably 50 mol% or less, particularly preferably 40 mol% or less.
The process is performed until the content becomes less than mol%.

The second step, acylation, is carried out by using the acylating agent in a ratio of 1.5 times or less, preferably 0.8 times or more and 1.3 times or less with respect to the hydroxycarboxylic acid. In this case, the dropping time of the acylating agent is 1
It is carried out for at least 0 minutes, preferably at least 20 minutes. The contact with the acylating agent is carried out at 80 to 350 ° C, preferably 100 to 300 ° C, more preferably 120 to 26 ° C.
The reaction is performed at 0 ° C. and may be performed in the presence of an inert gas such as N ₂ . The acylation may be carried out by lowering the system to the boiling point of the acylating agent or lower. The reaction is carried out for 10 minutes or more to 10 hours, preferably for 20 minutes or more to 5 hours. As the acylating agent, acetic anhydride, propionic anhydride, butyric anhydride, benzoic anhydride and the like can be used. Any of those generally usable as the acylating agent can be used, and among them, the reactive agent is used. Acetic anhydride is a typical one in terms of cost and cost.

The third stage polymerization is carried out at 200 ° C. to 350 ° C., preferably at 220 ° C. to 330 ° C. In this case, it is preferable to gradually reduce the pressure in the initial stage, and to gradually reduce the pressure from 760 mmHg to 1 mmHg. The time required is 30 minutes or more, preferably 60 minutes or more.
It is important to gradually reduce the pressure from 0 mmHg / min to 1 mmHg / min.

In the method of the present invention, in any one of the first to third steps, an antimony catalyst is used. The antimony catalyst of the present invention is not particularly limited as long as it is a commonly known antimony compound. Not done. In an antimony compound, antimony exists in a positive pentavalent, positive trivalent, or negative trivalent state, but sometimes does not exist at these normal valences. Usually, oxides, halides, hydrides, antimony salts, metal antimonides and the like of antimony are used. Specific compounds include Sb ₂ O ₃ ,
_{Sb 2 O 5, SbF 3,} SbF 5, SbCl 3, SbC
_{l 5, SbBr 3, SbI 3} , SbOCl, Sb 4 O 5
Cl ₂ , Sb ₂ (SO ₄ ) ₃ , Li ₃ Sb, Na ₃ S
b, K ₃ Sb, Mg ₃ Sb ₂ , Ca ₃ Sb ₂ or the like is used, and may be used as a mixture. Preferably, antimony trioxide (Sb ₂ O ₃ ) is used.

Each of the above-mentioned first to third steps can be usually carried out without a catalyst, but if necessary, a transesterification catalyst, a polycondensation catalyst, an acylation catalyst, a decarboxylic acid catalyst or the like is generally used. ing. When these catalysts are added in the reaction system before the stage in which their effectiveness is expected, there is no significant difference in catalytic action at any stage. That is, for example, a catalyst added in order to expect a catalytic action in the third stage may be added at the initial monomer charging. The antimony-based catalyst of the present invention may be added at any stage before the third stage of reduced pressure polymerization, or may be used alone, as in the case of using these other catalyst systems. May be used in combination with the above catalyst. The amount of antimony-based catalyst used is 5 to 5 with respect to the polymer.
0000 ppm, preferably 50-5000 ppm.

The liquid crystalline copolyester produced according to the present invention can also be compounded with a filler by adding a filler, and in this case, the improved hydrolysis resistance is maintained as it is. As a filler used for compounding,
All fillers commonly used in liquid crystal polymers can be used. For example, glass fibers, carbon fibers, metal fibers, whiskers such as potassium titanate, silica, alumina, silica alumina, silica magnesia, titania, calcium carbonate, barium sulfate, talc, mica, gypsum, inorganic fillers such as glass flakes and the like. No. When compounding these fillers, by adding a specific bisoxazoline derivative and a specific bisepoxy compound, it is possible to obtain a liquid crystal polyester resin composition further improved in hydrolysis resistance than in the case of no addition. It is possible.

[0016]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples unless it departs from the gist. Example 1 178.1 g (1.289) of P-hydroxybenzoic acid was placed in a glass polymerization tube equipped with a stirring blade, an N ₂ inlet, and a reduced-pressure port.
Mol), polyethylene terephthalate oligomer
9 g (0.322 mole as the amount of repeating units), antimony trioxide 132mg were charged, vacuum and N ₂ substitution was repeated three times, finally satisfy the N _2, N ₂ stream of 0.5 l / min flow rate Put on. When the polymerization tube was immersed in an oil bath at 220 ° C., the contents were dissolved in about 30 minutes. Therefore, stirring was started, and after the temperature was increased, transesterification was performed for 1 hour to produce a copolymerized oligomer. Thereafter, the temperature was lowered to 140 ° C. in about 30 minutes, and then 151 g (1.482 mol) of acetic anhydride was added dropwise over 30 minutes, and stirring was continued for another 1 hour to effect acylation. Then the temperature of the oil bath is set to 290 ° C
The temperature is raised over 2 hours until the temperature rises, and then the pressure is gradually reduced to initiate polymerization. Two hours after the start of the pressure reduction, the pressure was reduced to a high vacuum of 0.3 mmHg, and polymerization was performed for 2 hours and 40 minutes.

After the polymerization product is taken out by breaking the glass polymerization tube into chips, the product is vacuum-dried at 130 ° C. overnight. The melt viscosity of the polymer obtained (measured at 275 ° C., 1000 / sec using Capillograph 1B (manufactured by Toyo Seiki Co., Ltd.)) was 500 poise. This pellet
Ultra-small injection molding machine incorporating a scale-down mold of a test piece specified by ASTM (Sumitomo Heavy Industries, Ltd.)
Using Minimat M8 / 7A) and a resin temperature of 290
Injection molding was performed at 100 ° C. and a mold temperature of 100 ° C. Tensile strength, tensile elongation and Izod impact strength (1/1 /
8 inch notch) and Vicat softening point are each AST
MD-638, -D-256 and JIS-K7206
Was measured. In addition, a pressure cooker test was performed using these test pieces as hydrolysis resistance evaluation. That is, the tensile strength after performing the pressure cooker treatment for 48 hours, and the Izod impact strength were measured,
The degree of hydrolysis resistance was judged from the retention rate. still,
Here, the pressure cooker treatment refers to leaving in a closed vessel in which hot water is present under saturated steam at 120 ° C. for a predetermined time. Table 1 shows these results.
And Table 2.

Comparative Example 1 A polymer was prepared in the same manner as described in Example 1 except that 0.07373 g of stannous acetate was used as a catalyst, and its hydrolysis resistance was evaluated in Example 1 And compared. The results are shown in Tables 1 and 2. Comparative Example 2 A polymer was produced in the same manner as in Example 1, except that 0.036 g of zinc acetate dihydrate was used as the catalyst. Compared. The results are shown in Tables 1 and 2.

[0019]

[Table 1]

[Table 2]

[0020]

The liquid crystalline copolyester produced by the method of the present invention generally has a low molding shrinkage, a good fluidity, a low burr generation and a very low elastic modulus. It has properties such as high properties, low post-shrinkage rate of injection molded articles, and good chemical resistance. Among them, it has particularly good fluidity, and its hydrolysis resistance is greatly improved. Therefore, it is suitably used especially for parts used under severe conditions such as high temperature and high humidity and a heat cycle (repetition of temperature rise and fall) (for example, around an engine of an automobile).

Claims (1)

(57) [Claims] 1. A compound represented by the general formula (A): —CO—R ¹ —CO—O—R ² —O— (A) wherein R ¹ is a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms; A divalent alicyclic hydrocarbon group of the formulas 4 to 20 or /
And a divalent aliphatic hydrocarbon group having 1 to 40 carbon atoms (provided that the hydrogen atom in the aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl or alkoxy group having 1 to 4 carbon atoms) Wherein R ² is a divalent aliphatic hydrocarbon group having 2 to 40 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. A hydrogen group (however, a hydrogen atom of the aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl or alkoxy group having 1 to 4 carbon atoms), or a polyalkylene oxide divalent having a molecular weight of 80 to 8000 A raw material oligoester comprising a repeating unit represented by｝ representing a radical is 5-95 mol% in terms of the amount of the repeating unit, and HO—R ³ —COOH (B) wherein R ³ is The number of carbon atoms forming an aromatic ring is from 6 to 20 A divalent aromatic hydrocarbon group (however, a hydrogen atom of an aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl or alkoxy group having 1 to 4 carbon atoms)} 95-5 mol% of an acid is reacted to form a copolymerized oligomer (first step), then acylation is performed by adding an acylating agent (second step), and polymerization is performed under reduced pressure (third step). A method for producing a liquid crystalline copolyester, characterized in that an antimony-based catalyst is used as a catalyst in a three-stage reaction.