JP2001279117A - Ferroelectric polymeric material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change a polymeric material, which is difficult to be polarized because it has neither a glass transition temperature nor a melting point though it is expected to exhibit ferroelectric properties, into polarizable one and to utilize the polymeric material as a ferroelectric material. SOLUTION: A liquid crystal polymer such as a thermotropic liquid crystal polyester, or the like, is incorporated with a ferroelectric polymer not having a glass transition temperature and/or a melting point such as a wholly aromatic polyamide polymer, and the like, in an amount of 40-90 wt.% based on the total weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric material made of a polymer material, which is expected to exhibit ferroelectricity, but does not exhibit a glass transition temperature or a melting point, so that polarization treatment is difficult. The present invention relates to a ferroelectric polymer material that expresses ferroelectricity by enabling a polarization process on the polymer material.

[0002]

2. Description of the Related Art Conventionally, PbT has been used as a ferroelectric material.
metal oxides such as iO ₃ , LiTaO ₃ , BaTiO ₃ , and PbZrTiO ₃ ; vinylidene fluoride polymers represented by polyvinylidene fluoride and a copolymer of vinylidene fluoride and trifluoroethylene; cyanide Polymeric polymers such as a copolymer of vinylidene and vinyl acetate are known.

[0003] Among them, the former metal oxides have the advantage of high pyroelectricity and excellent heat resistance, but have poor flexibility and are difficult to form. Therefore, there is a problem that it is unsuitable as a material for a piezoelectric element having a large area, a thin film, and a complicated shape.

On the other hand, a polymer material has a lower piezoelectric / pyroelectric coefficient than a metal oxide material, and has a higher coercive electric field value for inverting polarization. However, since the specific heat is small and the dielectric constant is small, the figure of merit is good, and since the value of the coercive electric field is stable, application to optical memory materials, actuators, memory materials, and the like is being studied.

[0005] When a polymer material is used as a ferroelectric material, it is necessary to develop ferroelectricity with some exceptions such as a copolymer of vinylidene fluoride and trifluoroethylene. , Above the glass transition temperature of the polymer,
An electric field is applied to the polymer for a certain period of time at a temperature equal to or lower than the melting point, and the polymer is cooled while maintaining the electric field, that is, a so-called poling treatment is performed. The dipoles in the molecule need to be aligned in one direction. Residual polarization is formed by this dipole orientation, and ferroelectricity is developed.

Therefore, in order to form a polymer material and use it as a ferroelectric material, it is necessary that the polymer material has at least a glass transition temperature.

[0007]

However, from the viewpoint of molecular structure, even a polymer material expected to have certain excellent physical properties has a glass transition temperature and a melting point due to its properties. When the polymer material is insoluble in a solvent, it is difficult to mold the polymer, and the polymer material is rarely used as a functional material.

[0008] Polymer-based ferroelectric materials also include polyvinylidene fluoride currently used, vinylidene fluoride-based copolymers of vinylidene fluoride and trifluoroethylene, and vinylidene fluoride-based polymers of vinylidene cyanide and vinyl acetate. In addition to copolymers and not-yet-used non-odd nylons whose ferroelectric properties are known, although their molecular structure is expected to have ferroelectricity, their glass transition temperature and melting point Some polymer materials are not used because they do not have a polymer.

As an example, a wholly aromatic polyamide, in particular, has excellent heat resistance and chemical resistance, so that it is used as a heat-resistant fiber or a highly elastic fiber, while having a large dipole moment. Since it has an amide bond, it is expected to exhibit ferroelectricity similar to that of an odd-number nylon by properly selecting an aromatic structure.

However, in most cases, a wholly aromatic polyamide does not have a glass transition temperature or a melting point, so that it cannot be subjected to a polarization treatment and can be used as a ferroelectric material. No reports have been made.

As described above, when used as a polymer-based ferroelectric material, in practice, excellent characteristics are obtained due to the restriction that the polymer material has a glass transition temperature and a melting point. At present, the usefulness of the expected polymer materials is hindered.

Accordingly, an object of the present invention is to make it possible to polarize a polymer material which is expected to exhibit ferroelectricity but is difficult to be polarized because it does not show a glass transition point or a melting point, An object of the present invention is to provide a ferroelectric polymer material that can be used as a ferroelectric material.

[0013]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a ferroelectric polymer having no glass transition temperature and / or melting point has high liquid crystallinity. It has been found that polarization can be achieved by mixing molecules, and as a result, it can be used as a ferroelectric material.

In particular, it is desirable that the ferroelectric polymer having no glass transition temperature and / or melting point is made of a wholly aromatic polyamide, and that the liquid crystalline polymer is made of a thermotropic liquid crystalline polyester. The content of the liquid crystalline polymer is desirably 40 to 90% by weight based on the total amount.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The ferroelectric polymer material of the present invention comprises:
It is composed of a mixture of a ferroelectric polymer having no glass transition temperature and / or melting point and a liquid crystalline polymer. (Ferroelectric Polymer) In the present invention, the ferroelectric polymer having no glass transition temperature and / or melting point includes at least one of an amide bond, a urea bond, and a urethane bond having a dipole moment. It is desirable to have a group, specifically, at least one kind of wholly aromatic polyamide, wholly aromatic polyurea, and wholly aromatic polyurethane. Among these, heat resistance,
A wholly aromatic polyamide is most useful because it has excellent chemical resistance and the like. As this wholly aromatic polyamide,
Formulas (1) to (5) in Chemical Formula 1 below can be given as specific examples.

[0016]

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This wholly aromatic polyamide has an amide bond in the main chain, and is expected to have ferroelectricity due to the large dipole moment (μ _D = 3.5 _D ) of the amide bond. . However, since a wholly aromatic polyamide generally does not have a glass transition temperature or a melting point, it is difficult to sufficiently perform polarization treatment, and cannot be used as a ferroelectric material in general.

On the other hand, since this wholly aromatic polyamide is excellent in heat resistance, chemical resistance, and mechanical strength, if it can be used as a ferroelectric material, it will have excellent heat resistance and mechanical strength. It is considered that the dielectric polymer material can be applied to various fields.

The wholly aromatic polyamide in the present invention is generally prepared from a corresponding aromatic diamine compound and an aromatic dibasic acid chloride by a low-temperature solution polymerization method using N, N-dimethylacetamide or the like as a solvent. Can be synthesized by In this method, the molecular weight can be adjusted by changing the monomer concentration or the reaction time, or adding water.

Further, since the wholly aromatic polyamide is composed of an aromatic ring and an amide bond, it has high rigidity, and is excellent in heat resistance and mechanical strength. On the other hand, due to its rigidity, it is conceivable that the moldability such as the solubility in a solvent is reduced, but this problem is caused by the polymerization time,
The problem is solved by appropriately selecting the monomer concentration at the time of polymerization.

The molecular weight of the ferroelectric polymer in the present invention may be sufficient as long as it forms a film. On the other hand, when the ferroelectric polymer maintains solubility in a solvent and mixes with a liquid crystalline polymer. Desirably, no phase separation occurs. Specifically, it is desirable that the intrinsic viscosity in N-methyl-2-pyrrolidinone (hereinafter, referred to as NMP) is 0.2 to 3.0 dL / g, particularly 0.4 to 2.0 dL / g. . If the intrinsic viscosity is less than 0.2 dL / g, it is difficult to form a film. If the intrinsic viscosity is higher than 3.0 dL / g, mixing with a liquid crystalline polymer will result in insufficient mixing at the molecular chain level, possibly causing phase separation. (Liquid-Crystalline Polymer) The present invention provides a mixture of the above-mentioned glass transition temperature and / or a ferroelectric polymer having no melting point with a liquid-crystalline polymer, so that the mixture has a glass transition temperature. Or a melting point, thereby enabling a polarization treatment, and as a result, a polymer material having ferroelectricity can be obtained.

As the liquid crystalline polymer in the present invention, a thermotropic liquid crystal polymer is preferably used. A thermotropic liquid crystal polymer is a polymer that exhibits liquid crystallinity in a certain temperature range in a molten state, and in a liquid crystal state, molecular chains are aligned in one direction.

Further, the liquid crystalline polymer needs to be a polymer having high compatibility with the ferroelectric polymer. From such a point, thermotropic liquid crystalline polyester, thermotropic liquid crystalline polyesteramide, thermotropic liquid crystalline polyester amide, and the like. At least one selected from the group of liquid crystalline polyazomethines is preferred.

Among these, thermotropic liquid crystalline polyester can synthesize polymers having any molecular structure such as block copolymers and random copolymers with polyamide, and has high compatibility with the wholly aromatic polyamide. It is most preferably used in this respect.

Specific examples of this thermotropic liquid crystalline polyester include polyesters represented by the following formulas (6) to (10).

[0026]

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The above-mentioned thermotropic liquid crystalline polyester can be synthesized by a known method. For example, the polyester represented by the formula (6) is obtained by heating polyethylene terephthalate and 4-acetoxybenzoic acid at 270 ° C. under reduced pressure,
It can be easily obtained by condensation.

The liquid crystalline polymer must be dissolved in a solvent in which the ferroelectric polymer is soluble. For example, in the case of the above polyester, by appropriately selecting the mixing ratio of the monomers and the polymerization time, A polymer such as a polyester that can be dissolved in a predetermined solvent can be easily synthesized.

In the present invention, for example, when a wholly aromatic polyamide having an amide bond is mixed with a thermotropic liquid crystalline polymer, the polymer chain of the wholly aromatic polyamide is spatially large using the liquid crystalline polymer as a matrix. You will be able to exercise. Therefore, when the mixture is heated, the polymer chains of the polyamide can move together with the liquid crystal polymer, and the orientation of the polymer chains of the liquid crystalline polymer allows
The polymer chains of one polyamide are also oriented to some extent. When an electric field is applied in this state, the dipoles of the amide bond are aligned in the direction of the applied electric field, and the polymer chains of the polyamide are oriented like liquid crystal polymers. Next, when the mixture is rapidly cooled in a state where an electric field is applied, the orientation state can be frozen and maintained, and as a result, the mixture exhibits stable ferroelectricity.

The above-mentioned action is achieved by the ferroelectric polymer,
Even when the mixture has a urea bond or a urethane bond, the mixture stably exhibits ferroelectricity with the same action as described above.

The glass transition temperature of the liquid crystalline polymer in the present invention is preferably 50 ° C. or higher, more preferably 75 ° C. or higher. If the glass transition temperature is lower than this, the film is easily affected by the surrounding environment after the film is formed, and the expression of ferroelectricity may be unstable. Further, the liquid crystal temperature range is preferably 350 ° C. or less, more preferably 300 ° C. or less. If the liquid crystal temperature range is higher than this temperature, the polymer may be oxidized or decomposed during the heat treatment as described later, which is not preferable.

In the present invention, the content of the liquid crystalline polymer in the mixture is preferably 40 to 90% by weight, more preferably 50 to 85% by weight. 40
When the content is less than 10% by weight, the mixture may not have a glass transition temperature or a melting point. When the content is 90% by weight or more, the polarization treatment is facilitated, but the content of the ferroelectric polymer is reduced. When the amount is too small, the ferroelectricity may not be sufficiently developed.

In the mixture of the present invention, first, a ferroelectric polymer and a liquid crystalline polymer are dissolved in a common solvent. At this time, the concentration of the solution is less than 0.01 g / mL. If the concentration at this time is 0.01 g / mL or more, the degree of dispersion of the polymer is low, and each polymer may not be uniformly dispersed.

Next, this solution is heated to 80 ° C. or more, particularly 90 ° C.
After stirring for 3 hours or more, particularly 4 hours or more while heating at the above temperature, the solution is concentrated to a concentration of 0.1 g / mL or more, and the concentrated solution is applied to a desired substrate surface by spin coating, dip coating, or the like. By coating, a film composed of a mixture of polymers is obtained. When the heating temperature at the time of concentration is lower than 80 ° C., the dispersion of the polymer becomes insufficient, and when the concentration after the concentration does not reach 0.1 g / mL, the film formability decreases,
In some cases, a uniform film cannot be formed.

Next, the film is heated to a temperature at which the liquid crystalline polymer exhibits liquid crystal for a certain period of time, and then rapidly cooled, whereby the polymer chains are oriented. Further, in order to orient dipoles such as amide bond, urethane bond and urea bond, the film is subjected to a poling treatment.

In the poling treatment, a metal electrode thin film is formed on the film by a method such as sputtering, vapor deposition, or paste coating, and then the film is heated to a temperature equal to or higher than the glass transition temperature of the liquid crystalline polymer and equal to or lower than the melting point. In this state, an electric field strength that does not cause dielectric breakdown is applied, and the film is rapidly cooled in a state where the electric field is applied. By this treatment, the polymer chains of a polymer such as a wholly aromatic polyamide are oriented, and dipoles such as amide bonds are aligned in one direction, so that the mixture has ferroelectricity.

As described above, according to the present invention, by mixing a liquid crystalline polymer with a ferroelectric polymer such as a wholly aromatic polyamide, the mixture is given a glass transition temperature to enable polarization treatment. In addition, the ferroelectricity can be stably exhibited by aligning the polymer chains and maintaining the alignment state.

[0038]

The present invention will be described in more detail with reference to the following examples. The properties of the synthesized polymer were evaluated by the following methods. (Heat resistance) The synthesized polymer was measured by thermogravimetric analysis under the following conditions, and the temperature at which the weight was reduced by 10% from the measurement start temperature was determined, and this temperature was used as a measure of heat resistance.

Measurement start temperature: 30 ° C. Measurement end temperature: 1000 ° C. Heating rate: 10 ° C./min Measurement atmosphere: air (glass transition point, melting point) The glass transition point and melting point of the synthesized polymer are indicated by a differential scanning calorimeter. (DSC) was used and measured under the following conditions.

Measurement start temperature: 30 ° C. Measurement end temperature: 320 ° C. Heating rate: 10 ° C./min Measurement atmosphere: nitrogen (intrinsic viscosity) The intrinsic viscosity was measured by an Ubbelohde viscometer. The NMP solution having a concentration of 1.0 g / dL was adjusted at 3 to 5 points, the flow time of each solution at 30 ° C., and the NM
The relative viscosity η _r is determined from the flow time of only P, and ln (η _r
A curve plotting -1) / (concentration) against the solution concentration was extrapolated to zero concentration, and the point was defined as the intrinsic viscosity. (Ferroelectricity) RT6000S
The polarization P (mC / m ² ) was plotted against the electric field E (V) using (manufactured by Radiant Inc.), and the remanent polarization value was determined from the PE hysteresis curve. Example 1 1.015 g of terephthaloyl chloride was dissolved in 15 mL of N, N-dimethylacetamide (hereinafter referred to as DMAc) and cooled in an ice bath. 0.761 g of 3,5-diaminobenzoic acid was added to this solution under nitrogen and stirred. Thereafter, the ice bath was removed, and the reaction solution was stirred at room temperature under nitrogen for 3 hours. After the completion of the reaction, the reaction solution was poured into 300 mL of ethanol, and the precipitate was separated by filtration. The precipitate separated by filtration was washed with water and acetone, and then dried under reduced pressure at 60 ° C. to obtain 1.41 g (100% yield) of a wholly aromatic polyamide represented by the formula (1).

The polymer was soluble in DMAc, N, N-dimethylformamide, NMP and the like. The intrinsic viscosity in NMP at 30 ° C. was 0.473 dL / g.

Further, in the air, the temperature when the weight of the polyamide was reduced by 10% was about 400 ° C., indicating high heat resistance. On the other hand, as a result of measurement by DSC, no glass transition temperature or melting point was observed.

13.452 g of polyethylene terephthalate resin and 5.405 g of p-acetoxybenzoic acid were charged into a three-necked flask. One of the three-necked flasks was used for introducing nitrogen, one for stirring, and the other for decompression and exhaust. The pressure in the flask was reduced, and the raw material was dried by heating to 110 ° C. After 30 minutes, nitrogen was introduced and the mixture was stirred at 280 ° C for about 30 minutes. After all the raw materials were melted, the mixture was stirred at 280 ° C. while reducing the pressure in the flask. Four hours later, the flask was cooled, the product was taken out and dissolved in NMP, and the solution was poured into a large amount of ethanol. The precipitate was separated by filtration and dried to obtain a powdery thermotropic liquid crystalline polyester represented by the formula (6).

This polyester is soluble in NMP,
The intrinsic viscosity in NMP at 30 ° C. is 0.409 dL
/ G.

As a result of DSC measurement, the polyester had a glass transition temperature of 87 ° C. and a melting point of 212 ° C.

Next, 0.08 g of the polyamide represented by the formula (1) and 0.1% of the polyester represented by the formula (6) were added.
12 g was weighed, added to 25 mL of NMP, and stirred at 90 ° C. After 4 hours, the solution was concentrated at 120 ° C. under reduced pressure to 2 mL. The concentrated solution was filtered with a 0.2 μm filter, spin-coated on a glass substrate coated with ITO (Indiumu Tin Oxide) at 2000 rpm for 60 seconds, and dried under reduced pressure at 120 ° C. for 1 hour. Spin coating under the same conditions was repeated twice, and finally, drying was performed under reduced pressure at 120 ° C. for 12 hours to completely evaporate NMP.

After heating the produced film at 240 ° C. for 15 minutes, it was rapidly cooled to room temperature, and the film became transparent. The thickness of the film was about 0.8 μm. After forming a gold electrode on this film by sputtering, 140
C., and an electric field was applied for about 30 minutes with the electric field strength set to 80 V / μm. Next, the film was cooled to room temperature while a voltage was applied.

For this film, the polarization P (mC / m
^Two) Is plotted against the electric field E (V).
E hysteresis curve was obtained and the value of remanent polarization was 61 mC
/ M ^TwoMet. This remanent polarization value changes for 3 months at room temperature
Did not. Example 2 9.91 g of hydroquinone and 11.15 g of 1,8-di
Bromooctane, 11.33 g potassium carbonate, 1 g
Potassium iodide is dissolved in 50 mL of tetrahydrofuran.
Refluxed overnight. To this mixture was added 50 mL of ethyl acetate and then
Add 50 mL of water with and extract the product with ethyl acetate
You. The organic layer was separated, and 50 mL of ethyl acetate was added to the remaining aqueous layer.
And the organic layer was separated again. Combine organic layers and
Add magnesium sulfate water and dehydrate.
Was filtered off, and the solvent was distilled off from the filtrate. Hex the residue
Column chromatography using 1: 1 ethyl acetate as eluent
To the 1,8-bis (4-hydroxyfe
9.75 g (noxy) octane (yield 72%) was separated and purified.
Made.

Next, 7.92 g of 1,8-bis (4,4-bis (4)
-Hydroxyphenoxy) octane was dissolved. To this solution, 100 mL of a TCE solution in which 4.88 g of terephthaloyl chloride was dissolved was added dropwise under nitrogen, and reacted at room temperature. After 24 hours, the reaction was diluted with 600 mL of acetone. The resulting precipitate was separated by filtration, washed with water and acetone, and dried at 70 ° C. under reduced pressure to obtain 10.16 g of a liquid crystalline polyester represented by the formula (8).
(92% yield).

This polyester is soluble in NMP,
0.479 dL intrinsic viscosity in NMP at 30 ° C.
/ G.

As a result of DSC measurement, the polyester had a glass transition temperature of 91 ° C. and a melting point of 238 ° C.

With respect to the polyamide represented by the formula (1) and the polyester represented by the formula (8), the same operation as in (Example 1) was performed to produce a film composed of a mixture.

After heating the produced film at 270 ° C. for 15 minutes, it was rapidly cooled to room temperature, and the film became transparent. The thickness of the film was about 1.1 μm. After forming a gold electrode on this film by sputtering, 160
C., and an electric field was applied for about 30 minutes with the electric field strength set to 80 V / μm. Next, the film was cooled to room temperature while a voltage was applied.

For this film, the polarization P (mC / m
^Two) Is plotted against the electric field E (V).
E hysteresis curve was obtained and the value of remanent polarization was 65 mC
/ M ^TwoMet. This remanent polarization value changes for 3 months at room temperature
Did not. Comparative Example 1 Only the wholly aromatic polyamide represented by the formula (1)
g, without mixing with liquid crystalline polyester (Example 1)
Perform the same operation as described above to obtain a film with a thickness of about 0.8 μm.
Produced. Fill consisting only of this wholly aromatic polyamide
Polarization P (C / m^Two) For the electric field E (V)
Plotted, a PE hysteresis curve was obtained.
However, the value of remanent polarization was 5.2 mC / m^TwoMet. Example 3 A wholly aromatic polyamide represented by the formula (1)
g, 0.06 g of the polyester represented by the formula (6)
Then, the same operation as described below (Example 1) was performed, and
A 0.9 μm film was produced.

When the polarization P (mC / m ² ) was plotted against the electric field E (V) with respect to the film composed of this mixture, a PE hysteresis curve was obtained, but the value of the remanent polarization was 12 mC / m 2. m ² .

Example 4 1.396 g of 4,4'-biphenyldicarbonyl chloride was dissolved in 15 mL of DMAc, and the solution was cooled in an ice bath. 0.761 g of 3,5-
Diaminobenzoic acid was added under nitrogen and stirred. Thereafter, the ice bath was removed, and the reaction solution was stirred at room temperature under nitrogen for 3 hours. After the completion of the reaction, the reaction solution was poured into 300 mL of ethanol, and the precipitate was separated by filtration. The precipitate separated by filtration is water,
After washing with acetone, vacuum drying was performed at 60 ° C. to obtain 1.65 g (yield 92%) of a wholly aromatic polyamide represented by the following formula (3).

The polymer was soluble in DMAc, N, N-dimethylformamide, NMP and the like. The intrinsic viscosity in NMP at 30 ° C. was 0.519 dL / g.

Further, in air, the temperature when the weight of this polyamide was reduced by 10% was about 400 ° C., indicating high heat resistance. On the other hand, as a result of DSC measurement, no glass transition temperature or melting point was observed.

Next, a polyamide represented by the formula (2):
And the polyester represented by the formula (6)
Under the same conditions as in (Example 1), a film was produced and a polarization treatment was performed. The thickness of the film was 1.0 μm.

For this film, the polarization P (mC / m
^Two) Is plotted against the electric field E (V).
An E hysteresis curve was obtained, and the value of remanent polarization was 57 mC
/ M ^TwoMet. This remanent polarization value changes for 3 months at room temperature
Did not. Comparative Example 2 Only the wholly aromatic polyamide represented by the formula (2)
g and using no liquid crystalline polyester (Example 4)
Under the same conditions, a film was prepared and a polarization treatment was performed.

For this film, the polarization P (mC / m
² ) plotted against electric field E (V), P-
An E hysteresis curve was obtained, but the value of remanent polarization was 6.
It was 0 mC / m ² . Example 5 3.643 g of 5-hydroxyisophthalic acid in 10 mL
Was added to 15 mL of thionyl chloride, and the mixture was refluxed for 3 hours. After 3 hours, unreacted thionyl chloride with benzene was distilled off under reduced pressure, and the residue was further dried under reduced pressure for 6 hours to obtain 4.37 g of 5-hydroxyisophthalic acid dichloride.

The above-mentioned 5-hydroxyisophthalic acid dichloride (1.095 g) was dissolved in 15 mL of DMAc,
This was cooled in an ice bath. 0.541
g of p-phenylenediamine was added under nitrogen and stirred. Thereafter, the ice bath was removed, and the reaction solution was stirred at room temperature under nitrogen for 3 hours. After the reaction is completed, add 300 mL of the reaction solution.
Of ethanol and the precipitate was separated by filtration. The precipitate separated by filtration was washed with water and acetone, and then dried under reduced pressure at 60 ° C. to obtain a wholly aromatic polyamide represented by the following formula (4).
12 g (88% yield) were obtained.

The polymer was soluble in DMAc, N, N-dimethylformamide, NMP and the like. The intrinsic viscosity in NMP at 30 ° C. was 0.415 dL / g.

Further, in air, the temperature when the weight of the polyamide was reduced by 10% was about 400 ° C., indicating high heat resistance. On the other hand, as a result of DSC measurement, no glass transition temperature or melting point was observed.

Next, a polyamide represented by the formula (3):
And the polyester represented by the formula (6)
Under the same conditions as in (Example 1), a film was produced and a polarization treatment was performed. The thickness of the film was 0.7 μm.

For this film, the polarization P (mC / m
^Two) Is plotted against the electric field E (V).
E hysteresis curve was obtained and the value of remanent polarization was 62 mC
/ M ^TwoMet. This remanent polarization value changes for 3 months at room temperature
Did not. Comparative Example 3 Only a wholly aromatic polyamide represented by the formula (3)
g and using no liquid crystalline polyester (Example 5)
Under the same conditions, a film was prepared and a polarization treatment was performed.

For this film, the polarization P (mC / m
² ) plotted against electric field E (V), P-
An E hysteresis curve was obtained, but the value of remanent polarization was 5.
It was 7 mC / m ² . Example 6 0.04 g of the polyamide represented by the formula (1) and 0.16 g of the polyester represented by the formula (6) were weighed,
Thereafter, the same operation as in Example 1 is performed, and the film thickness is about 0.8 μm
Was produced.

The film made of this mixture was subjected to the same polarization treatment as in Example 1, and the polarization P (mC / m ² ) was plotted against the electric field E (V). As a result, a PE hysteresis curve was obtained. And the value of remanent polarization is 48 mC / m ²
Met. This remanent polarization value did not change for 3 months at room temperature. Example 7 0.04 g of the polyamide represented by the formula (2) and 0.16 g of the polyester represented by the formula (6) were weighed,
Thereafter, the same operation as in Example 1 was performed, and a film thickness of about 1.0 μm
Was produced.

The film made of this mixture was subjected to the same polarization treatment as in Example 1, and the polarization P (mC / m ² ) was plotted against the electric field E (V). As a result, a PE hysteresis curve was obtained. And the value of remanent polarization is 39 mC / m ²
Met. This remanent polarization value did not change for 3 months at room temperature. Example 8 0.04 g of the polyamide represented by the formula (3) and 0.16 g of the polyester represented by the formula (6) were weighed,
Thereafter, the same operation as in Example 1 is performed, and the film thickness is about 0.8 μm
Was produced.

The film made of this mixture was subjected to the same polarization treatment as in Example 1, and the polarization P (mC / m ² ) was plotted against the electric field E (V). As a result, a PE hysteresis curve was obtained. And the value of remanent polarization is 49 mC / m ²
Met. This remanent polarization value did not change for 3 months at room temperature.

As described above, Examples 1 to 8 and Comparative Examples 1 to 3
Table 1 summarizes the results. As can be seen from Table 1,
In the mixture, stable ferroelectricity was developed by enabling the polarization treatment.

[0072]

[Table 1]

[0073]

As described in detail above, according to the present invention, a polymer material which is expected to exhibit ferroelectricity, but which does not exhibit a glass transition point or a melting point and which is difficult to be subjected to a polarization treatment, is used. By mixing a liquid crystalline polymer, a polarization process can be performed, and the polymer material can be used as an excellent ferroelectric material.

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Claims (3)

[Claims] 1. A ferroelectric polymer material comprising a mixture of a ferroelectric polymer having no glass transition temperature and / or melting point and a liquid crystalline polymer. 2. The method according to claim 1, wherein said ferroelectric polymer having no glass transition temperature and / or melting point comprises a wholly aromatic polyamide, and said liquid crystalline polymer comprises a thermotropic liquid crystalline polyester. Item 7. The ferroelectric polymer material according to Item 1. 3. The content of the liquid crystalline polymer is 40% of the total amount.
2. The ferroelectric polymer material according to claim 1, wherein the amount of the ferroelectric polymer material is from 90 to 90% by weight.