JPH07116279B2 - Aromatic copolyester - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a novel thermotropic aromatic copolyester capable of melt processing at relatively low temperatures.

[Conventional technology and its problems]

In recent years, various engineering plastics have been developed, and liquid crystal polymers having optical anisotropy have attracted particular attention. Conventionally, as liquid crystal polymers, P-hydroxybenzoic acid homopolymers and polymers of terephthalic acid and hydroquinone have been known. However, since these polymers have high melting points of 610 ° C and 596 ° C, respectively, they are accompanied by decomposition of the polymer. Is difficult to melt process without (Adva
nces in Polymer Science, 60/61 , 61 (1984)). P-
Copolymers with hydroxybenzoic acid, terephthalic acid and hydroquinone have also been proposed (JP-B-47-47870).
No.), it has a high melting point of 500 ° C. or higher and has a problem of melt processability.

Various proposals have been made so far regarding methods for lowering the melting point of liquid crystal polymers (Brit. Polymer Journal, 132 (19
80)). Polyester containing 2,2'-dimethylbiphenyl-4,4'-dicarboxylic acid as a monomer component (Makromo
l.Chem., 189 , 2029 (1988), Makromol.Chem.Makromol Sy
mp. 26 , 47 (1989)), JP-A No. 64-66231), polyester containing 2,2'-bis (trifluoromethyl) -biphenyl-4,4'-dicarboxylic acid as a monomer component (Jour.
nal of Polymer Sci., Part C, Polymer Letters, 25 , 11
(1987), Makromolecules, 20 , 2374 (1987)) and the like are known. However, 2,2'-disubstituted biphenyl-4,4 '
-Dicarboxylic acids interfere with the coplanarity of the phenyl ring and thus reduce the crystallinity of the polymer. It is generally pointed out that polymers having low crystallinity do not have sufficient mechanical strength, and the like.

[Technical means for solving problems]

The present inventors have conducted intensive studies for the purpose of obtaining a polyester that can be melt-processed at a relatively low temperature, for example, a temperature of 400 ° C. or lower, and as a result, found an aromatic copolyester having liquid crystallinity and capable of being melt-processed. The present invention has been reached.

The present invention consists essentially of the following repeating units I, II and III, wherein the molar ratio of repeating unit I to repeating unit II is 10/90
It provides an aromatic copolyester which is ~ 99/1.

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.

The present invention relates to a wholly aromatic polyester composed of the above-mentioned three kinds of repeating units, and these copolyesters show optical anisotropy (liquid crystallinity) in a molten state when observed by a polarizing microscope.

The wholly aromatic polyester of the present invention forms a molten state at a relatively low temperature, for example, a temperature of 400 ° C. or less, and can be made into a bulk molded article, a film, a fiber, etc. by various commonly known molding processing methods. it can. Further, since it dissolves in an organic polar solvent such as pentafluorophenol and P-chlorophenol, it is possible to obtain a molded product by a dissolution processing method. These molded products can be widely used for electric, electronic and automobile materials. As a remarkable property, since it has liquid crystallinity in a molten state, it is possible to form a highly molecularly oriented molded product, and thus it is possible to produce a polymer material excellent in mechanical strength.

The repeating unit I represented by the following formula forming the aromatic copolyester of the present invention is 3,3'-dimethylbiphenyl-4,4'-dicarboxylic acid, its dicarboxylic acid ester,
It is derived from a dicarboxylic acid halide or the like.

The 3,3'-dimethylbiphenyl-4,4'-dicarboxylic acid can be synthesized, for example, by an oxidative coupling reaction of alkyl orthotoluate (Japanese Patent Application No. 63-2672).
No. 02 and applicant: Ube Industries, Ltd., Name: Biphenyl compound manufacturing method and new biphenyl compound, filing date:
Patent of August 18, 1989).

The repeating unit II represented by the following formula and forming the aromatic polyester of the present invention is derived from terephthalic acid, its acid ester, acid halide and the like.

The repeating unit III shown below in the formula forming the aromatic copolyester of the present invention is derived from a hydroquinone derivative.

The hydroquinone derivative has 1 to 1 carbon atoms such as hydroquinone, methylhydroquinone, ethylhydroquinone, propylhydroquinone and butylhydroquinone.
Specific examples thereof include alkyl group-substituted hydroquinone of 8, aryl group-substituted hydroquinone such as phenylhydroquinone, halogen atom-substituted hydroquinone and diacetyl derivatives thereof. In the present invention, as the repeating unit III, a mixture derived from the above-mentioned plural kinds of hydroquinone derivatives can be used.

The aromatic copolyester of the present invention has a molar ratio of repeating unit I and repeating unit II of 10/90 to 99/1 and a molar ratio of repeating unit I and repeating unit II of less than 10/90. The melting temperature of the group-copolyester becomes high and the molding process is difficult.
Further, the repeating unit (I + II) and the repeating unit III are constituted in substantially equimolar amounts.

In addition to the repeating units I, II, and III described above, the repeating unit I and / or repeating unit II and / or repeating unit III may be substituted with another repeating unit capable of forming an ester bond. Specific examples of the repeating unit capable of forming another ester bond include isophthalic acid and naphthalene-1,
5-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyl sulfone-4,4'-dicarboxylic acid,
Dicarboxy units such as those derived from diphenylketone-4,4'-dicarboxylic acid, 2,2'-diphenylpropane-4,4'-dicarboxylic acid, resorcin, 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) Dioxy units such as those derived from sulfone, bis (4-hydroxyphenyl) ether, m-hydroxybenzoic acid, 4-hydroxy-4'-carboxydiphenyl ether, 4-hydroxy-4'-carboxybiphenyl, 1-hydroxy- Oxycarboxy units such as those derived from 4-naphthoic acid can be mentioned.

The substitution ratio of these substituted repeating units is such that the repeating unit I, in order to make the melting point of the aromatic copolyester relatively low,
It is preferably 10 mol% or less based on the total amount of repeating units II and III.

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. Specific examples of the production method include polycondensation of dicarboxylic acid dichloride and diol in the presence of a tertiary amine, polycondensation of dicarboxylic acid diphenyl ester and diol by a dephenol method, and dicarboxylic acid and diol diacetyl. A method of polycondensing a derivative by a deacetic acid method may be mentioned.

A particularly preferred method is a deacetic acid method. In this method, the reaction temperature is 230 to 350 ° C., the reaction time is 1 to 10 hours, and the temperature is raised stepwise to distill off acetic acid, and then the pressure is reduced (about 0.5 torr). The reaction is completed.

The polycondensation reaction can be carried out in the presence or absence of a catalyst. Specific examples of the catalyst include stannous acetate, antimony trioxide, magnesium, titanium tetrabutoxide,
Examples thereof include sodium acetate.

Aromatic copolyester produced by the above methods,
It has a logarithmic viscosity (η _inh ) of 0.5 or more at a concentration of 0.2 g / dl in pentafluorophenol at 60 ° C.

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.

〔Example〕

 Examples 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 methods.

i. Optical anisotropy; place the sample on a polarizing microscope and make it by Rincom
Using a TH600RMS type heating device, the temperature was raised at 10 ° C./min under a nitrogen stream, and the naked eye was observed.

ii. Thermal decomposition initiation temperature: Using a DuPont 990TGA device, the sample was heated in nitrogen at 10 ° C./min, and the change in weight with time was observed.

iii. Melting point; using a DuPont 990DSC instrument, place the sample in nitrogen at 10
The temperature was raised at ° C / min and an endothermic peak was observed.

iv. Logarithmic viscosity; 0,0 in pentafluorophenol at 60 ° C.
The sample was dissolved at a concentration of 2 g / dl and measured using an Ubbelohde viscometer. η _inh was calculated according to the following equation.

η _inh = 1n (t / t ₀ ) / c where t ₀ is the drop time of pentafluorophenol, t is the drop time of the sample solution, and c is the concentration of the sample.

Examples 1 to 8 The upper part of a glass separable three-necked flask was used in a stainless steel container, and a stirrer, a nitrogen introduction tube, and a Claisen were attached. The amount of 3,3'-dimethylbiphenyl-4,4'-dicarboxylic acid (PA), terephthalic acid (TPA), hydroquinone diacetate derivative [hydroquinone diacetate] used in this container as shown in Table 1 was used. (HQ), methylhydroquinone diacetate (MHQ), t-butylhydroquinone diacetate (BHQ), phenylhydroquinone diacetate (PHQ), chlorohydroquinone diacetate (CHQ)], degassed with a vacuum pump and replaced with nitrogen. Was repeated 4 times and then heated at 230 ° C. for 1 hour in a metal bath containing tin. The temperature was raised to 320 ° C. in 2 hours, and acetic acid was distilled off. Hold at 320 ℃ for 2 hours, then under 0.5torr vacuum
It was further heated for 30 minutes and then returned to room temperature while introducing nitrogen. The polymer was crushed, removed from the container, washed with dimethylformamide and acetone, and vacuum dried at 100 ° C.

The yield of the obtained polymer, the temperature showing the optical anisotropy, the melting point, the thermal decomposition initiation temperature, the logarithmic viscosity and the result of elemental analysis are shown in Table 1.

In Table 1, the melting point and the mark "1" indicate that the change of the endothermic peak is not clear.

 ─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-2-163117 (JP, A) JP-A-1-289830 (JP, A) JP-A-1-98622 (JP, A) JP-A-64- 66231 (JP, A) JP-A 1-26634 (JP, A) JP-A 63-72724 (JP, A) JP-A 62-260825 (JP, A) JP-A 58-91721 (JP, A)

Claims (1)

[Claims] 1. A compound consisting essentially of repeating units I, II and III of the formula: wherein the molar ratio of repeating unit I to repeating unit II is 10/9.
Aromatic copolyester that is 0-99 / 1. 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.