JP3432576B2 - Liquid crystalline polyester - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystalline polyester which is suitable for application to an optical element, in which glass for liquid crystal orientation is easily fixed and birefringence has a large wavelength dispersion.

[0002]

2. Description of the Related Art In recent years, polymer liquid crystals have been used in the field of high-performance materials utilizing high heat resistance and moldability, and functional materials utilizing the change of the liquid crystal phase structure due to external fields such as heat or electric field and phase fixation. Actively researched and developed in the field, and already commercialized in the field of high performance materials. On the other hand, in the field of functional materials, active research is being conducted with the aim of application to optical recording, nonlinear optical materials, liquid crystal alignment films, optical fibers, optical elements for liquid crystal display devices, etc., but none have been commercialized yet. When polymer liquid crystals are applied to functional materials, they can be broadly divided into applications that utilize dynamic changes in the phase transition of liquid crystals and applications that use the liquid crystal's unique molecular orientation as static elements. Most of them use the property of liquid crystal for light. The important requirements for polymer liquid crystals that can be applied to the latter liquid crystal alignment-fixed optical element are that the liquid crystal alignment is easy to fix and that the liquid crystal alignment is stable after fixation, and the property against light, that is, refraction It is possible to freely control the index, birefringence, wavelength dispersion of birefringence, and the like. In particular, if an optical element with a large wavelength dispersion of birefringence, which has recently been strongly demanded in the display field, can be manufactured from a polymer liquid crystal, it will be an epoch-making optical element together with the unique polarization property of a fixed liquid crystal alignment structure. Can be manufactured.

However, no polymer liquid crystal has been developed which has a large wavelength dispersion of birefringence and which can stably fix the liquid crystal alignment, which can be used as a material for such an optical element. It was the current situation.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have searched for a polymer liquid crystal having a large wavelength dispersion of birefringence, capable of stably fixing the liquid crystal orientation, and being used as a material for an optical element. It was found that a polyester having a glass phase at a temperature below the liquid crystal transition point and having a unit containing a biphenyl skeleton, a naphthalene skeleton or a stilbene skeleton in a bond forming a main chain as a constitutional unit satisfies these requirements, and finally The present invention has been reached.

[0005]

That is, the present invention has a unit containing at least one skeleton selected from a biphenyl skeleton, a naphthalene skeleton and a stilbene skeleton in a bond forming a main chain as a constitutional unit of polyester, and a liquid crystal It exhibits a liquid crystal state at a temperature higher than the transition point and a glass state at a temperature lower than the liquid crystal transition point, and is mixed in a phenol / tetrachloroethane mixed solvent (weight ratio 60/40) with 3
The intrinsic viscosity value measured at 0 ° C. is 0.05 to 0.5, and the wavelength dispersion value of birefringence expressed by the ratio of birefringence at a wavelength of light 450 nm and birefringence at 600 nm is 1.
It is 15-1.40 and relates to the liquid crystalline polyester characterized by the above-mentioned.

The present invention will be described in detail below. The polyester of the present invention essentially contains at least one unit selected from the group consisting of a biphenyl skeleton, a naphthalene skeleton, and a stilbene skeleton as a constitutional unit, and these units have a large birefringence which is an effect of the present invention. Plays an important role in achieving chromatic dispersion.

The biphenyl skeleton of these units is represented by the structural unit represented by the general formula (a), the naphthalene skeleton is represented by the general formula (b), and the stilbene skeleton is represented by the general formula (c). Structural unit.

[0008]

[Chemical 2]

In the general formulas (a), (b) and (c), A
And B each represent a carbonyl bond (C = O) or O, which may be the same or different, and X and Y are each F,
Cl, Br, and an alkyl group having 1 to 4 carbon atoms (for example, methyl group (hereinafter, Me group), ethyl group (hereinafter, Et group), propyl group (hereinafter, Pr group), isopropyl group (hereinafter, i-Pr).
Group), butyl group (hereinafter Bu group), isobutyl group (hereinafter i)
-Bu group), sec-butyl group (hereinafter s-Bu group), t
ert-butyl group (hereinafter referred to as t-Bu group), and may be the same or different, and m and n represent an integer of 0 to 4 and may be the same or different. .

The substitution position of X or Y in the above formula is not particularly limited, but in the general structural unit (a), 2, 2 ', 3, 3', 5, 5 ',
6, 6 ', 2 and 6', 2'and 6, 3 and 5 ', 3'and 5,
3 and 5 and 3 ′ and 5 ′, 2 and 3 and 5 and 6 and 2 ′ and 3 ′ and 5 ′ and 6 ′, and in the structural unit (b), 1, 3,
4, 5, 7, 8, 1 and 5, 4 and 8, and the structural unit (c)
, 2, 2 ', 3, 3', 5, 5 ', 6,
6 ', 2 and 2', 3 and 5 ', 3'and 5, 3, 5 and 3'and 5', 2 and 3, 5 and 6, 2 ', 3', 5 'and 6', etc. It can be mentioned as a suitable one.

These units include biphenyldicarboxylic acid or its derivative, substituted biphenyldicarboxylic acid or its derivative, biphenol or its derivative, substituted biphenol or its derivative, 4-hydroxy-4'-biphenylcarboxylic acid or its derivative, and substituted 4 -Hydroxy-4'-biphenylcarboxylic acid or a derivative thereof,
2,6-naphthalenedicarboxylic acid or its derivative, substituted 2,6-naphthalenedicarboxylic acid or its derivative,
6-hydroxy-2-naphthoic acid or its derivative, substituted 6-hydroxy-2-naphthoic acid or its derivative,
2,6-dihydroxynaphthalene or its derivative, substituted 2,6-dihydroxynaphthalene or its derivative,
Stilbene dicarboxylic acid or its derivative, substituted stilbene dicarboxylic acid or its derivative, 4,4′-dihydroxystilbene or its derivative or substituted 4,
4'-dihydroxystilbene or its derivative, 4 '
A unit derived from -hydroxy-4-stilbenecarboxylic acid or a derivative thereof and a substituted 4'-hydroxy-4-stilbenecarboxylic acid or a derivative thereof, and specifically, the following units can be exemplified.

[0012]

[Chemical 3] Such. Among these, the following units are particularly preferable.

[0013]

[Chemical 4]

As the constitutional unit of polyester, (a)
A unit derived from a dicarboxylic acid (hereinafter referred to as a dicarboxylic acid unit), (a) a unit derived from a diol (hereinafter referred to as a diol unit), and (c) a unit having a carboxyl group and a hydroxyl group at the same time. Examples thereof include units derived from oxycarboxylic acids (hereinafter referred to as oxycarboxylic acid units). The polyester is appropriately selected from these units. As the structure, (A) +
There are (a) type, (a) + (a) + (c) type, and (c) single type. By introducing the above structural units (a), (b) and (c) into at least one of the units (a), (b) and (c), the polyester having a large wavelength dispersion of birefringence of the present invention can be obtained. Obtainable.

Another important feature of the polyester of the present invention is that it exhibits a liquid crystal state at a temperature higher than the liquid crystal transition point and a glass state at a temperature lower than the liquid crystal transition point, and more preferably, lower than the liquid crystal transition point. It has a glass phase directly without going through a crystal phase at a temperature, whereby the liquid crystal orientation can be fixed to glass and used as an optical element. In order to express such properties, a polymer containing as a constituent component an ortho-substituted aromatic unit in which the bonds forming the main chain are ortho to each other is particularly preferably used. Specifically, the following catechol units, salicylic acid units, phthalic acid units, 2,3-
Naphthalenediol units, 2,3-naphthalenedicarboxylic acid units and substituted catechol units having substituents on these benzene rings, substituted salicylic acid units, substituted phthalic acid units, substituted 2,3-naphthalenediol units, substituted 2,
3-naphthalene dicarboxylic acid unit etc. can be mentioned.

[0016]

[Chemical 5] (X represents hydrogen, halogen such as Cl and Br, a methyl group, an ethyl group, a methoxy group, an ethoxy group or a phenyl group, and k is 0 to 2). The substitution position of the substituent X in the general formula is not particularly limited, but usually includes the following.

[0017]

[Chemical 6] Among these, the following can be exemplified as particularly preferable examples.

[0018]

[Chemical 7]

Examples of other units constituting the polyester of the present invention, (a) dicarboxylic acid unit, (i) diol unit and (u) oxycarboxylic acid unit are shown below. (A)
The following can be illustrated as the dicarboxylic acid unit.

[0020]

[Chemical 8] (Y represents hydrogen, halogen such as Cl or Br, a methyl group, an ethyl group, a methoxy group, an ethoxy group or a phenyl group. 1 is 0 to 2). The substitution position of the substituent Y in the general formula is not particularly limited, but usually includes the following.

[0021]

[Chemical 9] More specifically, for example,

[0022]

[Chemical 10] And so on. Also,

[0023]

[Chemical 11] And so on.

The following can be exemplified as the diol unit of (a).

[0025]

[Chemical 12] (Z represents hydrogen, halogen such as Cl and Br, a methyl group, an ethyl group, a methoxy group, an ethoxy group or a phenyl group, and m is 0 to 2). The substitution position of the substituent Z in the general formula is not particularly limited, but usually includes the following.

[0026]

[Chemical 13]

More specifically, for example,

[0028]

[Chemical 14] And so on. further

[0029]

[Chemical 15] And so on.

Examples of the oxycarboxylic acid unit (c) are as follows.

[0031]

[Chemical 16] (W represents hydrogen, halogen such as Cl and Br, methyl group, ethyl group, methoxy group, ethoxy group or phenyl group. P is 0 to 2). The substitution position of the substituent W in the general formula is not particularly limited, but usually includes the following.

[0032]

[Chemical 17]

More specifically, for example,

[0034]

[Chemical 18] And so on. further

[0035]

[Chemical 19] And so on.

The preferred liquid crystalline polyester of the present invention is
The structure is appropriately selected from these units ((A) + (B))
Type, (a) + (b) + (c) type, (c) single type, etc.) and at least one or more constitutional units selected from the group consisting of the structural units (a), (b) and (c) It includes units. Examples of suitable polyesters include the following.

[0037]

[Chemical 20]

[0038]

[Chemical 21]

[0039]

[Chemical formula 22]

[0040]

[Chemical formula 23]

[0041]

[Chemical formula 24]

[0042]

[Chemical 25]

[0043]

[Chemical formula 26]

The numbers such as a, b, c and d in the above structural units indicate the molar composition ratio, and the arrangement thereof is not particularly limited and may be block, random or the like.

As described above, it is essential that the polyester of the present invention has a unit containing a biphenyl skeleton, a naphthalene skeleton or a stilbene skeleton in the bond forming the main chain of the polymer as a constituent, and more preferably liquid crystal alignment. In order to facilitate the glass immobilization, the ortho-substituted aromatic unit in which the bonds forming the main chain of the polymer are ortho to each other is contained as a constituent component. The proportion of these polymers in the polymer is 5 mol% or more, and more preferably 7 mol% or more, in which the unit containing a biphenyl skeleton, a naphthalene skeleton or a stilbene skeleton. This amount is 5 mol%
If the amount is smaller than the above range, the desired polymer having a large dispersion of birefringence cannot be obtained, which is not preferable. The upper limit is usually 5
It is desirably 0% or less, preferably 40 mol% or less. Further, the ratio of the ortho-substituted aromatic unit is usually preferably in the range of 5 mol% to 40 mol%, particularly preferably in the range of 10 mol% to 35 mol%. If this value is less than 5 mol%, the polymer may have a crystalline phase in the temperature range lower than the liquid crystal transition point, and it may be difficult to fix the liquid crystal alignment to the glass. May decrease.

The molecular weights of these polymers are
For example, phenol / tetrachloroethane (60/40)
The logarithmic viscosity measured at 30 ° C. in a mixed solvent is usually 0.0
A range of 5 to 0.5, preferably 0.06 to 0.4 is preferred. When the logarithmic viscosity is less than 0.05, the strength of the obtained polymer becomes weak, and when it is more than 0.5, the viscosity at the time of liquid crystal formation is high, and the alignment property is lowered and the time required for the alignment is increased. Is not preferable when it is applied to an optical element. The glass transition point of these polyesters is also important and affects the stability of orientation after the orientation is fixed. It is desirable that the glass transition point is usually 0 ° C. or higher, preferably 30 ° C. or higher, considering that the glass transition point is generally used near room temperature depending on the application. If the glass transition temperature is lower than these temperatures, the liquid crystal structure once fixed may change when used near room temperature.
The function derived from the liquid crystal structure may be deteriorated.

The upper limit of the glass transition point is usually 300.
It is about ℃. The wavelength dispersion value of the birefringence of these polymers is represented by the K value, which is the ratio of the birefringence (Δn) when the wavelength of light is 450 nm and the birefringence when the wavelength is 600 nm, which is expressed by the formula (1). .

[0048]     K = Δn (450 nm) / Δn (600 nm) (1)

The K value of the polyester of the present invention is controlled mainly by the amount of the unit containing the biphenyl skeleton, the naphthalene skeleton or the stilbene skeleton introduced into the polymer, but is in the range of 1.15 to 1.40. , With a very large variance value. Generally, when the amount of these units is increased, the K value is also increased.
You can control the value. The liquid crystal layer of the present invention preferably exhibits a nematic liquid crystal layer.

The method for synthesizing the liquid crystalline polyester of the present invention is as follows:
It is not particularly limited, and it is synthesized by a polymerization method known in the art, for example, a melt polymerization method without using a solvent, or a solution polymerization method using a corresponding acid chloride of dicarboxylic acid. In the case of synthesizing by a melt polymerization method, for example, an acetylated product of a dicarboxylic acid corresponding to the structural unit and a diol corresponding to the structural unit, and / or an acetylated product of a hydroxycarboxylic acid corresponding to the structural unit is subjected to normal pressure at high temperature. Alternatively, it can be produced by polymerizing under reduced pressure or under vacuum.

Examples of the dicarboxylic acid corresponding to the above structural unit include dicarboxylic acids corresponding to the above general formulas (a), (b) and (c) and ortho-substituted aromatic units, and the above-mentioned "(a) dicarboxylic acid unit". And so on. As the carboxylic acid unit, specifically,

[0052]

[Chemical 27]

[0053]

[Chemical 28]

[0054]

[Chemical 29] And so on.

Examples of the acetylated diol corresponding to the above structural unit include the above-mentioned general formulas (a), (b) and (c).
And the acetylated diol corresponding to the ortho-substituted aromatic unit, the above-mentioned “(i) diol unit” and the like. Specifically as such diol acetylated product

[0056]

[Chemical 30]

[0057]

[Chemical 31]

[0058]

[Chemical 32] And so on.

As the acetylated product of hydroxycarboxylic acid corresponding to the above structural unit, the above-mentioned general formula (a),
Corresponding to (b) and (c) and the hydroxycarboxylic acid or “(u) oxycarboxylic acid unit” of the ortho-substituted aromatic unit. As the acetylated product of such hydroxycarboxylic acid, specifically,

[0060]

[Chemical 33]

[0061]

[Chemical 34]

The molecular weight can be easily adjusted by controlling the polymerization time or the charge composition. The polymerization conditions in that case are not particularly limited, but usually 150 ° C. to 350 ° C., preferably 200 to 300 ° C., and the reaction time is 30 minutes or more, preferably about 1 to 20 hours. In order to accelerate the polymerization reaction, conventionally known metal salts such as sodium acetate and zinc acetate, imidazoles and the like can also be used.

When the liquid crystalline polyester of the present invention is produced by the solution polymerization method, the corresponding dicarboxylic acid dichloride or hydroxycarboxylic acid chloride and diol are dissolved in a solvent, and the solution is added in the presence of an acid acceptor such as pyridine. The desired polyester can be easily obtained by heating.

As the dicarboxylic acid dichloride corresponding to the above structural unit, the above-mentioned general formulas (a), (b),
(C), a dicarboxylic acid dichloride corresponding to an ortho-substituted aromatic unit, a dicarboxylic acid dichloride corresponding to the above-mentioned "(a) dicarboxylic acid unit", and the like. Specific examples of the carboxylic acid dichloride include:

[0065]

[Chemical 35]

[0066]

[Chemical 36]

[0067]

[Chemical 37] And so on.

As the hydroxycarboxylic acid chloride corresponding to the above structural unit, general formulas (a), (b),
Examples of the hydroxycarboxylic acid chloride corresponding to (c) and the ortho-substituted aromatic unit, the hydroxycarboxylic acid chloride corresponding to the above-mentioned “(u) oxycarboxylic acid unit” and the like.

[0069]

[Chemical 38]

[0070]

[Chemical Formula 39]

The diol corresponding to the above structural unit corresponds to the diol corresponding to the above general formulas (a), (b) and (c) and the ortho-substituted aromatic unit and the above-mentioned "(i) diol unit". Examples of the diol include, specifically,

[0072]

[Chemical 40]

[0073]

[Chemical 41]

The solvent used is not particularly limited,
For example, halogen solvents such as o-dichlorobenzene, dichloroethane, tetrachloroethane, dimethyl sulfoxide (DMSO), dimethylformamide (DM
F), polar solvents such as N-methylpyrrolidone (NMP), and ether solvents such as tetrahydrofuran (THF) and dioxane. The acid acceptor is not particularly limited, and examples thereof include pyridine, triethylamine, tripropylamine and the like. The conditions for solution polymerization are not particularly limited, but are usually at a temperature of 50 to 20.
0 ° C., preferably 60 to 150 ° C., reaction time 1 hour to
It is 10 hours, preferably 2 hours to 7 hours. The composition of the raw material components charged is preferably the same as the structural unit composition of the polyester, and is not particularly limited as long as it is a range in which the raw material monomers form an ester bond.

[0075]

The liquid crystalline polyester of the present invention exhibits a large birefringence wavelength dispersion characteristic and has a glass state without crystallinity at a temperature lower than the liquid crystal transition point. By cooling to a temperature below the liquid crystal transition point (glass transition point), the alignment structure in the liquid crystal state can be fixed. The material thus obtained which is transparent and retains the liquid crystal alignment structure is industrially extremely valuable because it can be suitably used for various functional materials, especially optical elements. Further, the liquid crystalline polyester of the present invention is industrially excellent in its production method such that it can be easily structured industrially.

[0076]

EXAMPLES Examples will be described below, but the present invention is not limited thereto. The analytical methods used in the examples are as follows. (1) Determination of polymer composition The polymer was dissolved in deuterated chloroform or deuterated trifluoroacetic acid, and measured and determined by ¹ H-NMR (400 nm) of JHN-GX400 manufactured by JEOL.

(2) Measurement of logarithmic viscosity Using an Ubbelohde viscometer, the viscosity was measured at 30 ° C. in a phenol / tetrachloroethane (60/40 weight ratio) mixed solvent. (3) DSC measurement DuPont990 Thermal Analyze
It was measured using r 2. (4) Optical Microscope Observation Liquid crystallinity and the like were observed using a BH2 polarization microscope manufactured by Olympus Optical Co., Ltd.

(5) Measurement of wavelength dispersion of birefringence The sample used for measurement was coated with a polymer in a thickness of 1 to 4 μm on a glass with a polyimide alignment film of 50 mm × 50 mm and a thickness of 1 mm and rubbed at 180 ° C. From 240
After heat treatment at 5 ° C. for 5 to 60 minutes, it was cooled and orientation-fixed. The birefringence of the film is measured by a monochromator (using Nikon P-250: 600 lines / mm grating, wavelength range 170 nm to 1600 nm).
Wavelength range from 800 nm to 3 using monochromatic light emitted from
The measurement was performed by the Senarmont method at 50 nm and every 10 nm.
In the measurement by the Senarmont method, a Babinet Soleil compensator (manufactured by Applied Optoelectronics: phase variable range ± 180 ° for wavelength 900 nm) is used as an input / 4 plate for each wavelength, and a Glan-Thompson prism (manufactured by Applied Photoelectric: extinction ratio) is used as a polarizer. 1
(× 10 ⁻⁵ or more), and a photomultiplier tube (R636 manufactured by Hamamatsu Photonics) attached to an integrating sphere was used as a detector. The obtained measured value was fitted with the Cauchy's formula represented by Formula 1 to obtain the wavelength dispersion of the sample.

[0079] In Expression 1, λ is the measurement wavelength, Δnd (λ) is the retardation of the sample at the wavelength λ, and a, b, and c are parameters representing the birefringence dispersion of the sample.

The dispersion characteristic that can be determined by this measurement is exactly the retardation of the sample (product of birefringence and thickness of sample)
Is the dispersion characteristic of. However, if the same sample is measured at each wavelength, the thickness (d) of the sample does not change. Therefore, if the obtained dispersion characteristics are standardized at a certain wavelength (for example, 550 nm), the same wavelength ( Here, it is equivalent to the dispersion characteristic of birefringence normalized at 550 nm).

Example 1 80 mmol of terephthalic acid,
20 mmol of 4,4′-biphenyldicarboxylic acid, 30 mmol of hydroquinone diacetate and 70 mmol of catechol diacetate were heated and stirred under a nitrogen stream at 270 ° C. for 8 hours in a 300 ml flask with an acetic acid outflow cooling tube to synthesize a polymer. The obtained polymer was dissolved in tetrachloroethane and poured into a large amount of methanol to purify the polymer. The composition and ηinh of the obtained polymer are shown in Table 1. From DSC measurement and polarization microscope observation, Tg had a glass phase at 108 ° C. and showed a nematic liquid crystal phase at a higher temperature. Take a small amount of polymer on a slide glass,
220 on the hot plate with the cover glass on top
A sample obtained by heating and dropping at 10 ° C. for 10 minutes and then dropping it from a hot plate and cooling was transparent, and a nematic liquid crystal phase was completely fixed by observation with a polarizing microscope.
Further, the K value of this polymer is as large as 1.16,
It was found that the polymer of this example has a wavelength dispersion with large birefringence.

Comparative Example 1 100 mmo of terephthalic acid
270 ml of hydroquinone diacetate and 70 mmol of catechol diacetate under a nitrogen stream in a 300 ml flask with an acetic acid outlet cooling tube.
A polymer was synthesized by heating and stirring at 8 ° C. for 8 hours. The obtained polymer was dissolved in tetrachloroethane and poured into a large amount of methanol to purify the polymer. The composition and ηinh of the obtained polymer are shown in Table 1.
From DSC measurement and polarization microscope observation, Tg had a glass phase at 106 ° C. and showed a nematic liquid crystal phase at higher temperatures. A small amount of polymer was placed on a slide glass, a cover glass was placed on it, heated on a hot plate at 220 ° C for 10 minutes, and after adding a drop of water, the sample was taken down from the hot plate and cooled. The liquid crystal phase was completely fixed. However, since this polymer is a polymer obtained by removing 4,4'-biphenyldicarboxylic acid units from the polymer of Example 1, the K value was as small as 1.13 and the wavelength dispersion of birefringence was unsatisfactory.

Example 2 Terephthalic acid dichloride 8
5 mmol, 2,2'-dimethyl-4,4'-biphenyldicarboxylic acid dichloride 38 mmol, methylhydroquinone 50 mmol and catechol 78 mmol
Was dissolved in 500 ml of o-dichlorobenzene, 50 ml of pyridine as an acid acceptor was added, and the mixture was heated and stirred at 70 ° C. for 4 hours under a nitrogen stream to synthesize a polymer. The reaction solution was poured into a large amount of methanol to collect the precipitated polymer. The composition and ηinh of the obtained polymer are shown in Table 1. From DSC measurement and polarization microscope observation, Tg had a glass phase at 107 ° C. and showed a nematic liquid crystal phase at a higher temperature. A small amount of the polymer was placed on a slide glass, a cover glass was placed on the slide glass, heated on a hot plate at 200 ° C for 15 minutes, added with a chilled mixture, and the sample was taken down from the hot plate and cooled. The liquid crystal phase was completely fixed. The K value of this polymer is 1.1.
7, which is a large value, shows that the polymer of this example has a wavelength dispersion with a large birefringence.

[Comparative Example 2] The amount of terephthaloyl dichloride charged was 117 mmol, and 2,2'-dimethyl-
The polymers shown in Table 1 were synthesized in the same manner as in Example 2 except that the charged amount of 4,4'-biphenyldicarboxylic acid dichloride was changed to 8 mmol. This polymer had a nematic liquid crystal phase and was able to fix the liquid crystal orientation to glass, but the K value was as small as 1.14 and the birefringence was low because the proportion of the biphenyldicarboxylic acid unit in the polymer was as small as 3 mol%. Had insufficient wavelength dispersion characteristics.

[Examples 3 to 17] Examples 6, 7, and 11,
Polymers 14 and 17 were synthesized by the solution polymerization method according to Example 2 using the acid chloride of the corresponding acid, and in the other Examples by the melt polycondensation method according to Example 1. The properties of the obtained polymers are shown in Table 1. It was found that all the polymers showed a large K value of 1.15 to 1.26 and had a large birefringence wavelength dispersion characteristic.

[0086]

[Table 1]

[0087]

[Table 2]

[0088]

[Table 3]

[0089]

[Table 4]

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Iwane Shiozaki, 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Japan Central Research Institute of Petroleum Co., Ltd. (56) Reference JP 3-17121 (JP, A) Patent 3248038 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (2)

(57) [Claims] 1. A liquid crystal state having a unit containing at least one skeleton selected from a biphenyl skeleton, a naphthalene skeleton and a stilbene skeleton in a bond forming a main chain as a constitutional unit of polyester and having a liquid crystal state at a temperature higher than a liquid crystal transition point. Shows a glass state at a temperature lower than the liquid crystal transition point, and the intrinsic viscosity value measured at 30 ° C. in a phenol / tetrachloroethane mixed solvent (weight ratio 60/40) is 0.05 to 0.5, A liquid crystalline polyester having a wavelength dispersion value of birefringence of 1.15 to 1.40 expressed as a ratio of birefringence at a wavelength of light of 450 nm and birefringence at 600 nm. 2. A unit containing a biphenyl skeleton is represented by the general formula (a), a unit containing a naphthalene skeleton is represented by the general formula (b), a unit containing a stilbene skeleton is represented by the general formula (c), and the polyester thereof as a whole is used. The liquid crystalline polyester according to claim 1, wherein the content thereof is 5 mol% or more. [Chemical 1] However, A and B each represent a carbonyl bond or an oxygen atom, which may be the same or different, and X and Y are each F,
Cl, Br and an alkyl group having 1 to 4 carbon atoms, which may be the same or different, and m and n are 0.
It represents an integer of 4 and may be the same or different.