JPH03205423A - Aromatic copolyester - Google Patents

Abstract

PURPOSE:To obtain an aromatic polyester which has liquid crystal properties, can be fabricated by melting at a relatively low temperature and can give a molding of excellent mechanical strengths by using three specified kinds of repeating units. CONSTITUTION:Repeating units of formulas I, II and III (wherein R is H, 1-8C alkyl, aryl or halogen) are used to obtain an aromatic copolyester having a molar ratio of repeating units of formula I to repeating units of formula II of 10/90-99/1. This copolyester has liquid crystal properties in a molten state, can form a melt at a relatively low temperature, e.g. 400 deg.C or less, and can be formed into bulk molding, films, fibers, etc., by various usual molding processes. Because it can dissolve in an organic polar solvent such as pentafluorophenol, it can be formed into moldings by dissolution fabrication process. These moldings can extensively be used as electrical, electronic and automobile materials, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to novel thermotropic aromatic copolyesters that are melt processable 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, 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 they are difficult to decompose. It is difficult to melt process without
ience S trespass L + 6H 1984)). Copolymers with P-hydroxybenzoic acid, terephthalic acid and hydroquinone have also been proposed (Japanese Patent Publication No. 4'T-41810
No.), it has a high melting point of 500°C or more, and there are problems with melt processability.

Until now, various proposals have been made regarding methods of lowering the melting point of liquid crystal polymers (Brit. PolymerJ
132 (1980)). 2,2'-dimethylbiphenyl-4. Polyester containing 4'-dicarboxylic acid as a monomer (Makromol.Ch
em. , 189. 2029 (1988), Makro
mol. Chem. Makromol Symp. 26
．． 47<1989), JP-A No. 64-66231),
2. Polyester containing 2”-bis(trifluoromethyl)monobiphenyl-4,4′-dicarboxylic acid as one of the monomers (Journal of Polymer S
ci. , Part C+ Polymer Lett
ers+25.11 (1987), Makromo1
ecules, 20, 2374 (198'7)) are known. However, 2,2゛disubstituted biphenyl 4,
4"-dicarboxylic acid often interferes with the coplanarity of the phenyl ring, thus reducing the crystallinity of the polymer. Polymers with low crystallinity generally have disadvantages such as not having satisfactory mechanical strength. has been pointed out.

[Technical means to solve problems]

The present inventors have conducted intensive research aimed at obtaining a polyester that can be melt-processed at relatively low temperatures, for example, below 400°C, and as a result, they have discovered an aromatic copolyester that has liquid crystallinity and can be melt-processed. This heading led to the present invention.

The present invention provides an aromatic copolyester consisting essentially of repeating units I, II and III of the following formula, wherein the molar ratio of repeating unit I to repeating unit II is from 10/90 to 99/1. be.

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

The present invention relates to wholly aromatic copolyesters composed of the above three types of repeating units, and these copolyesters exhibit optical anisotropy (liquid crystallinity) in a molten state when observed under a polarizing microscope.

The wholly aromatic polyester of the present invention can be formed into a molten state at a relatively low temperature, for example, 400°C or less, and can be processed into bulk articles, films, fibers, etc. by various commonly known shaping methods. It can be done. Furthermore, since it dissolves in organic polar solvents such as pentafluorophenol and P-chlorophenol, it is possible to obtain shaped products by dissolution processing. These products can be widely used in electrical, electronic, and automotive materials. As a notable characteristic,
Since it has liquid crystallinity in a molten state, it can be made into a shaped article with highly oriented molecules, and therefore a polymer material with excellent mechanical properties can be produced.

The repeating unit I shown in the formula below forming the aromatic copolyester of the present invention is 3,3°-dimethylbiphenyl-4,4'-dicarboxylic acid, its dicarboxylic acid ester, dicarboxylic acid halide. It is derived from etc.

The above-mentioned 3,3゜-dimethylbiphenyl-4,4゛-dicarboxylic acid can be synthesized, for example, by oxidative coupling reaction of alkyl orthotoluate (Japanese Patent Application
No. 3-267202 and applicant: Ube Industries, Ltd.
Name: Process for producing biphenyl compound and novel biphenyl compound, Application date: Patent dated August 18, 1997).

The repeating unit (2) shown in the formula below, which constitutes the aromatic copolyester of the present invention, is derived from terephthalic acid, its acid ester, acid halide, or the like.

The repeating unit (2) shown in the formula below, which constitutes the aromatic copolyester 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 phenylhydroquinone, halogen atom-substituted hydroquinone, and diacetyl derivatives thereof. In the present invention,
As the repeating unit (2), a mixture derived from a plurality of the above-mentioned hydroquinone derivatives can be used.

The aromatic copolyester of the present invention has an aromatic The melting temperature of group copolyesters becomes high, making shaping processing difficult. Further, the repeating unit (I+n) and the repeating unit (2) are constituted in substantially equimolar amounts.

In addition to the above-mentioned repeating units I, ■, and ■, repeating units ■ and /
Alternatively, the repeating unit (■) and/or the repeating unit (■) may be substituted. Specific examples of repeating units that can form other ester bonds include isophthalic acid, naphthalene-1.5
-dicarboxylic acid, diphenyl ether-4,4°-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenylketone-4,4°-dicarboxylic acid, 2.
Dicarboxy units such as those derived from 2'-diphenylpropane-4,4'-dicarboxylic acid, resorcinol, 2,5-di-t-butylhydroquinone, 2.3.5
- }Limethylhydroquinone, 1,5-dihydroxynaphthalene, 2,2-bis(4-hydroxyphenyl)
Broban, bis(4-hydroxyphenyl)ken,
Bis(4-hydroxyphenyl)sulfone, bis(4-
dioxy units such as those derived from hydroxyphenyl) ether, m-hydroxybenzoic acid, 4-hydroxy-4'-monocarboxydiphenyl ether, 4-hydroxy-4'-monocarboxybiphenyl, 1-hydroxy-
Mention may be made of oxycarboxy units such as those derived from 4-naphthoic acid and the like.

The substitution ratio of these substituted repeating units is such that the repeating units ■,
The amount is preferably 10 mol % or less based on the total amount of repeating unit (1) and repeating unit (2).

There are no particular limitations on the method for producing the aromatic copolyester 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 tertiary azation, ■ Polycondensation of diphenyl ester of dicarboxylic acid and diol by dephenolization method, ■ Dicarpon 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 101 tin acetate, antimony trioxide, magnesium, titanium tetrabutoxide, and sodium acetate.

The aromatic copolyester produced by each of the above methods is
0.2g/in pentafluorophenol at 60°C
It has a logarithmic viscosity (ηi-+.) of 0.5 or more at a concentration of di.

The aromatic copolyester of the present invention melts at a relatively low temperature, and the 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 10'C/min under a nitrogen stream using a TH600RMS type heating device manufactured by Income Co., Ltd., and observed with the naked eye.

ii. Thermal decomposition start temperature; DuPont990 TGA
Using an apparatus, 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.

iii. Melting point: Using a DuPont 990 DSC device, the sample was heated at 10″C/min in nitrogen, and an endothermic peak was observed.

iv. Logarithmic viscosity. The sample was dissolved at a concentration of 0.2 g/di in pentafluorophenol at 60''C and measured using an Ubbelohde viscometer. η.- was calculated according to the following formula.

ηinh = in(t/to)/c where 70 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 8 A stainless steel container was equipped with a stirrer, a nitrogen introduction tube, and a Claisen using the upper part of a separable glass three-necked flask. In this container, 3,3'-dimethylbiphenyl-4,4''-dicarboxylic acid (P^), terephthalic acid (TPA), and hydroquinone diacetate derivative [hydroquinone diacetate derivative] were added in the amounts shown in Table 1. acetate (HQ), methylhydroquinone diacetate} (M
HQ), t-butylhydroquinone diacetate (BHQ)
), phenylhydroquinone diacetate (PHQ), chlorohydroquinone diacetate (C}IQ)), degassed with a vacuum bomb, and replaced with nitrogen four times.
Heated at 30°C for 1 hour. The temperature was raised to 320°C over 2 hours, and acetic acid was distilled off. After keeping it at 320℃ for 2 hours,
The mixture was further heated for 30 minutes under reduced pressure of 0.5 torr, and then 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 the obtained polymer, temperature showing optical anisotropy, melting point, thermal decomposition onset temperature, logarithmic viscosity, and elemental analysis results are as follows:
Shown in Table 1.

A single mark at the melting point in Table 1 indicates that the change in the endothermic peak is not clear.

(Margin below) 13 Go 4

Claims (1)

[Claims] Consists essentially of repeating units I, II and III of the following formula, and the molar ratio of repeating unit I to repeating unit II is 10/90 to 9.
Aromatic copolyester with a ratio of 9/1. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ I ▲There are mathematical formulas, chemical formulas, tables, etc.▼II ▲There are mathematical formulas, chemical formulas, tables, etc.▼III In the formula, R is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or Indicates an aryl group and a halogen atom.