JP2565793B2 - 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 a liquid crystal polymer, p-
Hydroxybenzoic acid homopolymers and polymers of terephthalic acid and hydroquinone are known, but their melting points are high at 610 ° C and 596 ° C, respectively, so it is difficult to melt-process them without decomposing the polymer. There (Ad
vances 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 on methods for lowering the melting point of liquid crystal polymers (Brit. Polymer Journal, 132).
(1980)). Polyester containing 2,2'-dimethylbiphenyl-4,4'-dicarboxylic acid as a monomer component (Makr
omol.Chem., 189 , 2029 (1988), Makromol.Chem.Makromol
Symp. 26 , 47 (1989), JP-A-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,
Therefore, the crystallinity of the polymer is reduced. In general, it has been pointed out that polymers having low crystallinity do not have satisfactory mechanical strength.

[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 repeating units I, II and III of the formula: wherein repeating unit I is 1 to 90 mol% of repeating unit (I + II + III), repeating units II and III are substantially equimolar. , And in pentafluorophenol at 60 ° C,
It provides an aromatic copolyester having a logarithmic viscosity (η _inh ) of 0.5 to 2.71 at a concentration of 0.2 g / dl.

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 copolyester consisting of the above-mentioned three types 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 has a relatively low temperature,
For example, a molten state can be formed at a temperature of 400 ° C. or lower, and a bulk molded product, a film, a fiber and the like can be formed by various commonly known molding processing methods. Further, since it is melted in an organic polar solvent such as pentafluorophenol or 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 obtain a highly molecularly oriented molded product, and thus it is possible to produce a polymer material having excellent mechanical strength.

The repeating unit I 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 II 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, etc. .

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. 63-267).
No. 202 and Japanese Patent Application No. 1-211334).

The repeating unit III forming the aromatic copolyester of the present invention is derived from a hydroquinone derivative. Examples of the hydroquinone derivative include hydroquinone, methylhydroquinone, ethylhydroquinone, propylhydroquinone, butylhydroquinone and other alkyl group-substituted hydroquinone having 1 to 8 carbon atoms, phenylhydroquinone and other aryl group-substituted hydroquinone,
Specific examples include 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.

In the aromatic copolyester of the present invention, the repeating unit I is 1 to 90 mol% of the repeating unit (I + II + III), the preferable range is 1 to 80 mol%, and the particularly preferable range is 1 to 70 mol%.
Is. When the repeating unit I exceeds 90 mol%, the melting temperature of the aromatic copolyester becomes high and the molding process is difficult. Further, the repeating unit 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, the repeating unit II and the 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, naphthalene-1,5-dicarboxylic acid,
Diphenyl ether-4,4'-dicarboxylic acid, diphenyl sulfone-4,4'-dicarboxylic acid, diphenyl ketone-4,4'-dicarboxylic acid, 2,2'-diphenylpropane-
Dicarboxy units such as derived from 4,4'-dicarboxylic acid, resorcin, 2,5-di-t-butylhydroquinone, 2,3,5-trimethylhydroquinone, 1,5-dihydroxynaphthalene, 2,2 -Dioxy units such as those derived from bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) ketone, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) ether, m-hydroxybenzoic acid Acid, 4-
Hydroxy-4'-carboxydiphenyl ether, 4
There may be mentioned oxycarboxy units such as those derived from -hydroxy-4'-carboxybiphenyl, 1-hydroxy-4-naphthoic acid and the like.

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 polyester relatively low,
It is preferably 10 mol% or less based on the total amount of II and III.

The method for producing the aromatic polyester of the present invention is not particularly limited and 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, sodium acetate and the like.

Aromatic polyester 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 polyester of the present invention melts at a relatively low temperature of 400 ° C. or lower, 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 990 TGA device, the sample was heated in nitrogen at 10 ° C./min, and the change in weight with time was observed.

iii. Melting point; the sample was placed under nitrogen in a DuPont 990 DSC device 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 7 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. 3,3'-Dimethylbiphenyl-4,4'-dicarboxylic acid (PA), p-acetoxybenzoic acid (PBA), hydroquinone diacetate derivative in the container in the amounts shown in Table 1. [Hydroquinone diacetate (HQ) Methyl hydroquinone diacetate (MHQ), t
-Butylhydroquinone diacetate (BHQ), phenylhydroquinone diacetate (PHQ), chlorohydroquinone diacetate (CHQ)] was charged, degassed with a vacuum pump, and nitrogen substitution was repeated 4 times, and then a metal bath in which tin was dissolved. Heat at 230-250 ℃ for 1 hour, then to 250-300 ℃
The temperature was raised for 2.5 hours to distill off acetic acid. Then 0.5 torr
The mixture was further heated under reduced pressure for 30 minutes and returned to room temperature while introducing nitrogen. Grind polymer out of container, wash with dimethylformamide and acetone,
It was dried in vacuum.

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 the melting point in Table 1, − indicates that the change in the endothermic peak is not clear.

Claims (1)

(57) [Claims] 1. A repeating unit consisting essentially of repeating units I, II and III, wherein repeating unit I is repeating unit (I + II + III).
1 to 90 mol%, repeating units II and III are substantially equimolar amounts, and a logarithmic viscosity (η _inh ) of 0.5 to 2.71 at a concentration of 0.2 g / dl in pentafluorophenol at 60 ° C.
Is an aromatic copolyester. 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.