JPH0397722A - Aromatic polyester - Google Patents

Abstract

PURPOSE:To provide the subject thermotropic polyester composed essentially of a plurality of specific recurring units, melting at a relatively low temperature, having liquid crystal nature and giving a molded article having excellent mechanical strength. CONSTITUTION:The objective polyester is composed essentially of the recurring units of formula I and formula II (R is H, 1-8C alkyl, aryl or halogen). The polyester is produced e.g. by deacetylating a diacetyl derivative of a dicarboxylic acid and a diol at a reaction temperature of 230-350 deg.C in the presence of a catalyst such as stannous acetate while raising the temperature in 1-10hr to distill out acetic acid and evacuating the system to proceed the reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel thermotropic aromatic polyester that can be melt-processed at relatively low temperatures. [Prior Art and Problems Therewith] In recent years, various engineering plastics have been developed, and liquid crystal polymers having optical anisotropy have attracted particular attention. Conventionally, P-hydroxybenzoic acid homopolymer and polymer of terephthalic acid and hydroquinone have been known as liquid crystal polymers, but these polymers have high melting points of 610°C and 596°C, respectively, so it is difficult to decompose the polymer. (Advances in Polymer Sc
ience, 60/61 +61 (1984)).

Copolymers with P-hydroxybenzoic acid, terephthalic acid and hydroquinone have also been proposed (Japanese Patent Publication No. 47-4
No. 7870'), has a high melting point of 500°C or more,
There is a problem with melt processability.

Until now, various proposals have been made regarding methods of lowering the melting point of liquid crystal polymers (Brit. PolymerJ
Journal, 132 (1980)). Polyester containing 2,2'-dimethylbiphenyl-4,4'-dicarboxylic acid as a monomer (Makromol.Ch
ew. ．． 189 2029 (1988). Makroi
ol. Chem. Makromol Symp. 26.
47 (1989)), polyester containing 2,2'-his(trifluoromethyl)monobiphenyl-4,4''-dicarboxylic acid as a monomer (Journal
of Polymer Sci. ．． Part C. Po
Lymer Letters, 25.11 (1987)
, Makromolecules, another. 2374 (1
987)) are known. However, 2,2°-disubstituted biphenyl-4,4'-dicarboxylic acids interfere with the coplanarity of the phenyl rings, thus reducing the crystallinity of the polymer. In general, it has been pointed out that polymers with low crystallinity have drawbacks such as not having satisfactory mechanical strength. [Technical means for solving the problem] As a result of intensive research aimed at obtaining a polyester that can be melt-processed at a relatively low temperature, for example, 400"C or less, the present inventors have found that liquid crystallinity has been improved. We have discovered an aromatic polyester that has the following properties and can be melt-processed, leading to the present invention.

The present invention provides an aromatic polyester consisting essentially of the following repeating units (1) and (2).

In the formula, R represents a hydrogen atom, an alkyl group or aryl group having 1 to 8 carbon atoms, or a halogen atom.

The present invention relates to wholly aromatic polyesters composed of the above two types of repeating units, and these polyesters exhibit optical anisotropy (liquid crystallinity) in a molten state when observed under a polarizing microscope. The wholly aromatic polyester of the present invention is formed into a molten state at a relatively low temperature, for example, 400°C or lower, and is formed into bulk shaped products, films, fibers, etc. by various commonly known molding methods. be able to. Furthermore, since it is soluble in organic polar solvents such as pentafluorophenol and P-chlorophenol, it is possible to obtain molded articles by a solution processing method. These products can be widely used in electrical, electronic, and automobile materials. One of its remarkable properties is that it has liquid crystallinity in the molten state, so it can be made into high-profile products with highly oriented molecules.
Therefore, a polymer material with excellent mechanical strength can be manufactured.

The repeating unit (2) shown in the lower part of the aromatic polyester of the present invention is 3,3'-dimethylbiphenyl-4.4°-dicarboxylic acid, its dicarboxylic acid ester, dicarboxylic acid halide, etc. It is derived from.

The above 3.3゛-dimethylbiphenyl-4.4゜-dicarboxylic acid can be synthesized, for example, by an oxidative coupling reaction of an alkyl orthotoluate (Japanese patent application No. 6
No. 3-267202 and applicant: Ube Industries, Ltd.
Name: Process for producing biphenyl compounds and novel biphenyl compounds; Application date: Patent dated August 18, 1997).

The repeating unit (2) shown in the lower part of the aromatic polyester of the present invention is derived from a hydroquinone derivative.

Hydroquinone derivatives include hydroquinone, methylhydroquinone, ethylhydroquinone, proylhydroquinone, butylhydroquinone, etc. having 1 to 1 carbon atoms.
Specific examples include alkyl group-substituted hydroquinone of No. 8, aryl group-substituted hydroquinone such as phenyl hydroquinone, halogen atom-substituted hydroquinone, and diacetyl derivatives thereof. In the present invention, a mixture derived from the plurality of types of hydroquinone derivatives described above can be used as the repeating unit (2). The aromatic polyester of the present invention has a structure in which repeating units I and (2) are substantially repeated alternately, but in addition, repeating units I and/or repeating units are formed by repeating units capable of forming other ester bonds. ■ may be replaced. Specific examples of repeating units capable of forming other ester bonds include isophthalic acid, naphthalene-1,5-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyl sulfone-4l4'-dicarboxylic acid, diphenyl ketone Dicarboxy units such as those derived from -4,4''-dicarboxylic acid, 2,2'-diphenylpropane-4,4''-dicarboxylic acid, resorcinol, 2,5
-di-t-butylhydroquinone, 2,3.5-}limethylhydroquinone, 1,5-dihydroxynaphthalene, 2,2-bis(4-hydroxyphenyl)brovane, bis(4-hydroxyphenyl)ketone, bis(4-hydroxyphenyl) −
dioxy units such as those derived from hydroxyphenyl) sulfone, bis(4-hydroxydiphenyl) ether, monohydroxybenzoic acid, 4-hydroxy-4-carboxydiphenyl ether, 4-hydroxy-4
Examples include oxycarboxy units derived from monocarboxybiphenyl, 1-hydroxy-4-naphthoic acid, and the like.

In order to make the melting point of the aromatic polyester relatively low, the substitution ratio of these substituted repeating units is preferably 10 mol % or less based on the total amount of repeating units (1) and (2). There are no particular limitations on the method for producing the aromatic polyester of the present invention, and it can be produced by a known ester polycondensation reaction. Specific examples of production methods include: ■ Polycondensation of dicarboxylic acid dichloride and diol in the presence of a tertiary atom; ■ Polycondensation of diphenyl ester of dicarboxylic acid and diol by dephenolization method; ■ Dicarboxylic acid dichloride and diol in the presence of a tertiary atom; An example is a method in which an acid and a diacetyl derivative of a diol are polycondensed by acetic acid removal method.

A particularly preferred method is the acetic acid removal method. In this method, the reaction temperature is 230 to 350°C and the reaction time is 1 to 10 hours.
orr) 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 stannous acetate, antimony trioxide, magnesium, titanium tetrabutoxide, and sodium acetate.

The aromatic polyester produced by each of the above methods is 6
0.2 g/di in pentafluorophenol at 0°C
It has a logarithmic viscosity (ηin& ) of 0.5 or more at a concentration of .

The aromatic polyester of the present invention melts at a relatively low temperature, and this polymer can be used to produce shaped articles with excellent mechanical strength.

〔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 method.

i. Optical anisotropy: A 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 TH600RMS type heating device manufactured by Linkam Co., Ltd., and observed with the naked eye.

ii. Thermal decomposition start temperature; DuPont990 TG
Using apparatus A, the temperature of the sample was raised in nitrogen at a rate of 10° C./min, and the change in weight over time was observed.

■． Melting point; using a DuPont 990 DSC device,
The sample was heated in nitrogen at 1O''C/min and an endothermic peak was observed.

ivl'tD viscosity (ηi,, ): A sample was dissolved in pentafluorophenol at 60°C at a concentration of 0.28/dl, and measured using an Ubbelohde viscometer. ηi
nk was calculated according to the following formula.

η=nh=In(t/to)/c However, t0
is the falling time of pentafluorophenol, t is the falling time of the sample solution, and C is the concentration of the sample.

Example 1 A stainless steel container was equipped with a stirrer, a nitrogen inlet tube, and a Claisen using the upper part of a three-necked glass Separate flask. In this container, 16.217 g of 3,3゛-dimethylbiphenyl-4,4゜-dicarboxylic acid (601II
M), 11.651 g of hydroquinone diacetate (60
mM), degassed with a vacuum pump, and replaced with nitrogen four times, then heated to 230°C in a metal bath containing dissolved tin. The temperature was raised to 300'C over 2.5 hours, and acetic acid was distilled off. Thereafter, it was further heated for 30 minutes under a reduced pressure of 0.5 torr, and returned to room temperature while introducing nitrogen. The polymer was ground and removed from the container, washed with dimethylformamide and acetone, and dried under vacuum at 100°C. The yield of polymer was 18.98 g (92% yield).

The obtained polymer exhibits optical anisotropy at temperatures above 310°C, has a melting point of 268°C, a thermal decomposition initiation temperature of 465°C,
Logarithmic viscosity was 2.28 dl/g. The results of elemental analysis were 76.03% carbon and 4.59% hydrogen. (
C! The calculated values of z H lb O a are 76.73% carbon and 4.68% hydrogen. ) Example 2 Methylhydroquinone diacetate instead of hydroquinone diacetate 12. The reaction was carried out in the same manner as in Example 1 except that 493g (60mM) was used, and 20.53g (60mM) was used.
A polymer was obtained with a yield of 95%.

The obtained polymer exhibits optical anisotropy at temperatures above 235°C, has a thermal decomposition onset temperature of 473°C, and has a logarithmic viscosity of 2.74.
It was dl/g. The results of elemental analysis are 77.42% carbon and 5.03% hydrogen.
Met. (The calculated value of C0H.Oa is carbon 77.
08% and hydrogen 5.06%. ) Example 3 The reaction was carried out in the same manner as in Example 1 except that 16.459 g (60 mM) of t-butylhydroquinone diacetate was used instead of hydroquinone diacetate, and 21.97 g (
A polymer was obtained with a yield of 91%. The obtained polymer exhibited optical anisotropy at temperatures above 275°C, had a melting point of 284°C, a thermal decomposition initiation temperature of 443°C, and a logarithmic viscosity of 1.44 dl/g.

The results of elemental analysis are 77.33% carbon and 6.10% hydrogen.
Met. (The calculated value of C z bH z 40 4 is 77.98% carbon and 6.04% hydrogen.) Example 4 Using 13.718 g (60 mM) of chlorohydroquinone diacetate instead of hydroquinone diacetate The reaction was carried out in the same manner as in Example 1 except that 2187 g (yield 96%) of a polymer was obtained.

The obtained polymer exhibits optical anisotropy at temperatures above 282°C, with a melting point of 220°C1 and a thermal decomposition initiation temperature of 427°C1.
Logarithmic viscosity was 2.81 dl/g. The results of elemental analysis are 69.13% carbon, 4.04% hydrogen, and 9.21% chlorine.
%Met. (The calculated values for CzzH+sC 104 are 69.75% carbon, 3.99% hydrogen, and 9.36% chlorine.
It is. ) Example 5 The reaction was carried out in the same manner as in Example 1 except that 16.217 g (60 mM) of phenylhydroquinone diacetate was used instead of hydroquinone diacetate, and 22.87 g (
A polymer was obtained with a yield of 91%.

The obtained polymer exhibits optical anisotropy at temperatures above 240°C, has a melting point of 240'C, and a thermal decomposition initiation temperature of 443°C.
, the logarithmic viscosity was 1.53 dl/g.

Claims (1)

[Claims] An aromatic polyester consisting essentially of repeating units I and II represented by the following formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ I ▲There are mathematical formulas, chemical formulas, tables, etc.▼II In the formula, R represents a hydrogen atom, an alkyl group or aryl group having 1 to 8 carbon atoms, or a halogen atom.