JP2588800B2 - Aromatic copolyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel thermotropic aromatic copolyester which can be melt-processed at a relatively low temperature.

2. Description of the Related Art In recent years, various engineering plastics have been developed. In particular, liquid crystal polymers having optical anisotropy have attracted attention. Conventionally, P-hydroxybenzoic acid homopolymers and polymers of terephthalic acid and hydroquinone are known as liquid crystal polymers, and these polymers have a melting point of 6 respectively.
Since the temperature is as high as 10 ° C. and 596 ° C., it is difficult to melt-process without decomposing the polymer (Advances i
n Polymer Science, 60/61, 6
1, 1984). Copolymers with P-hydroxybenzoic acid, terephthalic acid and hydroquinone have also been proposed (Japanese Patent Publication No. 47-87070), but have a high melting point of 500 ° C. or higher and have problems with melt processability. .

Various proposals have been made on methods for lowering the melting point of liquid crystal polymers (Brit. Pol.).
ymer Journal, 132 (1980)).
Polyester containing 2,2'-dimethylbiphenyl-4,4'-dicarboxylic acid as one component of a monomer (Makro
mol. Chem. 189, 2029, 1988.
Year, Makromol. Chem. Makromol
Symp. 26, 47, 1989, JP-A-64
No.-66231), a polyester containing 2,2′-bis (trifluoromethyl) -biphenyl-4,4′-dicarboxylic acid as one component of a monomer (Journal of
Polymer Sci. , Part C, Polym
er Letters, vol. 25, p. 11, 1987,
Makromolecules, 20, 2374,
1987). However, 2,2 'disubstituted biphenyl-4,4'-dicarboxylic acids interfere with the coplanarity of the phenyl ring, thus reducing the crystallinity of the polymer. In general, it has been pointed out that polymers having low crystallinity do not have satisfactory mechanical strength.

[0003]

SUMMARY OF THE INVENTION The present invention provides an aromatic copolyester having liquid crystallinity and capable of being melt-processed at a relatively low temperature, for example, at a temperature of 400.degree.

The present invention comprises a repeating unit A, B, C, D, E and F of the following formula:

[0004]

Embedded image (In the formula, R represents a hydrogen atom, an alkyl group or an aryl group having 1 to 8 carbon atoms, or a halogen atom.) [A +
B] / [A + B + C + D + E] molar ratio is 0 to 85/1
00, the molar ratio of B / [A + B] is greater than 0 and equal to or less than 1, and the molar ratio of [C + D] / [C + D + E] is 5/1.
An aromatic copolyester having a molar ratio of [C + D + E] and F is substantially equal to or larger than 1 and equal to or smaller than 1.

The present invention relates to a wholly aromatic copolyester comprising the above six kinds of repeating units,
These copolyesters, when observed under a polarizing microscope,
It shows optical anisotropy (liquid crystal properties) in a molten state. The wholly aromatic polyester of the present invention has a relatively low temperature, e.g.
A molten state is formed at the following temperature, and a bulk molded product, a film, a fiber, or the like can be formed by various commonly known molding methods. Further, since it is dissolved in an organic polar solvent such as pentafluorophenol and p-chlorophenol, it is possible to obtain a molded article by a solution processing method. These molded articles can be widely used for electric, electronic, automotive materials and the like. As a remarkable property, since it has liquid crystallinity in a molten state, a molded article having a high degree of molecular orientation can be obtained, and thus a polymer material having excellent mechanical strength can be produced.

The repeating unit A forming the aromatic copolyester of the present invention is derived from p-hydroxybenzoic acid, its acid ester, acid halide, p-acetoxybenzoic acid and the like. The repeating unit B forming the aromatic copolyester of the present invention is derived from 4-hydroxybiphenyl-4′-carboxylic acid, its acid ester, acid halide, 4-acetoxybiphenyl-4′-carboxylic acid and the like. It is a thing. The repeating unit C forming the aromatic copolyester of the present invention is derived from 3,3′-dimethylbiphenyl-4,4′-dicarboxylic acid, its dicarboxylic acid ester, dicarboxylic acid halide, and the like. . The repeating unit D forming the aromatic copolyester of the present invention is derived from 3,4′-dimethylbiphenyl-4,3′-dicarboxylic acid, its dicarboxylic acid ester, dicarboxylic acid halide and the like. .

The above 3,3'-dimethylbiphenyl-
4,4'-Dicarboxylic acid and 3,4'-dimethylbiphenyl-4,3'-dicarboxylic acid can be synthesized, for example, by an oxidative coupling reaction of alkyl orthotoluate (Japanese Patent Application No. 63-267202, and Japanese Patent Application No. 1-211334). The repeating unit E forming the aromatic copolyester of the present invention is derived from terephthalic acid, an acid ester thereof, an acid halide and the like. The repeating unit F forming the aromatic copolyester of the present invention is derived from a hydroquinone derivative. Examples of the hydroquinone derivative include hydroquinone, methylhydroquinone, ethylhydroquinone, propylhydroquinone, alkyl-substituted hydroquinone having 1 to 8 carbon atoms such as butylhydroquinone, aryl-substituted hydroquinone such as phenylhydroquinone, halogen-substituted hydroquinone, and diacetyl derivatives thereof. Specific examples are given. In the present invention, as the repeating unit F, a mixture derived from a plurality of types of hydroquinone derivatives described above can be used.

In the aromatic copolyester of the present invention, the molar ratio of [A + B] / [A + B + C + D + E] is 0.
８５85/100, preferably 0-78 / 100,
Particularly preferably, it is 0-70 / 100. If the molar ratio exceeds 85/100, the melting temperature of the aromatic copolyester becomes high, and molding processing is difficult. B / [A + B]
Is greater than 0 and 1 or less. [C + D] /
The molar ratio of [C + D + E] is greater than 5/100, preferably greater than 8/100 and 1 or less. When the molar ratio is less than 5/100, the melting temperature of the aromatic copolyester becomes high similarly to the above, and molding is difficult. [C + D + E] and F are constituted in substantially equimolar amounts.

In addition to the above-mentioned repeating units A, B, C, D, E and F, the repeating units A, B, C, D, E and F are replaced by a small amount of repeating units capable of forming other ester bonds. It may be. Specific examples of the repeating unit capable of forming another ester bond include isophthalic acid, naphthalene-1,5-dicarboxylic acid, diphenyl ether-4,
4'-dicarboxylic acid, diphenylsulfone-4,4'-
Dicarboxy units such as those derived from dicarboxylic acids, diphenyl ketone-4,4'-dicarboxylic acids, 2,2'-diphenylpropane-4,4'-dicarboxylic acids,
Resorcinol, 2,5-di-t-butylhydroquinone,
2,3,5-trimethylhydroquinone, 1,5-dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) ketone, bis (4-hydroxyphenyl) sulfone, bis (4 Dioxy units such as those derived from -hydroxyphenyl) ether, m-hydroxybenzoic acid, 4-
Hydroxy-4'-carboxydiphenyl ether, 1
Oxycarboxy units such as those derived from -hydroxy-4-naphthoic acid and the like. The substitution ratio of these substituted repeating units is determined so that the melting point of the aromatic copolyester is relatively low.
[C + D + E + F] is preferably 10 mol% or less.

The method for producing the aromatic copolyester of the present invention is not particularly limited, and the aromatic copolyester can be produced by a known ester polycondensation reaction. As a specific example of the manufacturing method,
Polycondensation of dicarboxylic acid dichloride and diol in the presence of tertiary amine, polycondensation of diphenyl ester of dicarboxylic acid and diol by phenol removal method, polycondensation of diacetyl derivative of dicarboxylic acid and diol by deacetic acid method Method. A particularly preferred method is a deacetic acid method. In this method, the temperature is increased stepwise at a reaction temperature of 230 to 350 ° C. for a reaction time of 1 to 10 hours to remove acetic acid, and then reduced in pressure (about 0.5 torr). To complete the reaction.

The polycondensation reaction can be carried out in the presence or absence of a catalyst. Specific examples of the catalyst include acetic acid
Examples include tin, antimony trioxide, magnesium, titanium tetrabutoxide, and sodium acetate. The aromatic copolyester produced by each of the above methods was prepared by adding 0.2% in pentafluorophenol at 60 ° C.
It has a logarithmic viscosity (η _inh ) of 0.5 or more at a concentration of g / dl. In the above polycondensation reaction, an antioxidant and a heat stabilizer such as hindered phenol and phosphites can be added to the reaction system within a range that does not greatly affect the physical properties of the obtained polymer. The aromatic copolyester of the present invention melts at a relatively low temperature, and a molded article having excellent mechanical strength can be produced using this polymer.

[0012]

Embodiments of the present invention will be described below. (Measurement method) Each physical property value shown in the examples of the present invention was measured by the following method. (1) Optical anisotropy: The sample was placed on a polarizing microscope, and the temperature was raised at a rate of 10 ° C./min under a nitrogen stream using a TH600 RMS type heating device manufactured by Linkham Inc., and observed visually. (2) Thermal decomposition onset temperature; SSC / Seiko Denshi Kogyo
Using a 5200 TGA instrument, the sample was placed in nitrogen at
And the change in weight over time was observed. (3) Melting point: SSC / 5200 manufactured by Seiko Denshi Kogyo KK
The sample was heated in nitrogen at a rate of 20 ° C./min using a DSC apparatus, and an endothermic peak was observed. (4) Logarithmic viscosity: A sample was dissolved in pentafluorophenol at a concentration of 0.2 g / dl at 60 ° C. and measured using an Ubbelohde viscometer. η _inh was calculated according to the following equation. η _inh = ln (t / t _{0 ′} ) / c where t ₀ is the falling time of pentafluorophenol, t is the falling time of the sample solution, and c is the concentration of the sample.

Examples 1 to 3 Using a glass separable three-necked flask in the upper part of a stainless steel container (100 ml), a stirrer, a nitrogen inlet tube,
I installed Claisen. The amount of 3,3'-dimethylbiphenyl-
4,4'-dicarboxylic acid (PA), 3,4'-dimethylbiphenyl-4,3'-dicarboxylic acid (QA), terephthalic acid (TPA), p-acetoxybenzoic acid (PB
A), 4-acetoxybiphenyl-4'-carboxylic acid (BCA) and hydroquinone diacetate (HQ) were charged, degassed by a vacuum pump, and replaced with nitrogen three times, and then placed in a metal bath in which tin was dissolved. Heated at 240 ° C. for 1 hour. The temperature was raised to 300 ° C. in 3 hours to distill acetic acid. 3
After maintaining at 00 ° C. for 1 hour, the mixture was further heated under a reduced pressure of 0.2 torr for 1 hour, and then returned to room temperature while introducing nitrogen. The polymer is crushed and taken out of the container, washed with dimethylformamide and acetone, and heated at 100 ° C.
And vacuum dried. Table 2 shows the yield of the obtained polymer, the temperature showing the optical anisotropy, the melting point, the thermal decomposition onset temperature, the logarithmic viscosity and the result of elemental analysis. (Below)

[Table 1]

[Table 2]

Claims (1)

(57) [Claims] 1. It is composed of repeating units A, B, C, D, E and F of the following formula: (In the formula, R represents a hydrogen atom, an alkyl group or an aryl group having 1 to 8 carbon atoms, or a halogen atom.) [A +
B] / [A + B + C + D + E] molar ratio is 0 to 85/1
00, the molar ratio of B / [A + B] is greater than 0 and equal to or less than 1, and the molar ratio of [C + D] / [C + D + E] is 5/1.
An aromatic copolyester having a molar ratio of [C + D + E] and F substantially equal to or larger than 00 and equal to or smaller than 1;