JPH0843810A - Electrical insulating film and ferroelectric liquid crystal panel formed by using the same - Google Patents

Abstract

PURPOSE:To provide electrical insulating films which are easily formable and have an electrical conductivity and dielectric property in combination and to provide a ferroelectric liquid crystal panel which hardly generates electrical conduction between a pair of transparent electrodes facing each other via a ferroelectric liquid crystal layer and has good bistability even if ferroelectric liquid crystals are oriented by a roll orienting method in production process. CONSTITUTION:This electrical insulating layers 14 are formed by dispersing conductive particulates consisting of a material having a specific resistance <=1X10<8>OMEGA.cm into a high-polymer compd. having a specific dielectric constant <=15. The layers are the films having the specific resistance 1X10<2> to 5X10<9>OMEGA.cm, the specific dielectric constant >=10 and a film thickness >=0.20mum. The ferroelectric liquid crystal panel 11 has the two electrical insulating films 14 facing each other and the ferroelectric liquid crystal layer 15 formed between these two electrical insulating films 14. The electrical insulating films are the electrical insulating films 14 described above. The electrical insulating films 14 are formed at least via transparent electrodes 13 on the main surface of the substrates 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric insulating film, and in particular, a ferroelectric liquid crystal panel, which is suitable as a member for preventing conduction between two transparent electrodes opposed to each other through a ferroelectric liquid crystal layer. The present invention relates to an insulating film and a ferroelectric liquid crystal panel using the insulating film.

[0002]

2. Description of the Related Art In a ferroelectric liquid crystal panel using a ferroelectric liquid crystal as a liquid crystal layer material, when the thickness of the ferroelectric liquid crystal layer is made thin (for example, 2 μm), it is unique to other liquid crystal panels. A characteristic, that is, a memory phenomenon called bistability and a high-speed response of optical switching are expressed. Therefore, at present, the development and practical use of the ferroelectric liquid crystal panel are being actively pursued in order to promote the practical use of the ferroelectric liquid crystal display device, the spatial light modulator and the like utilizing the above characteristics.

The above-mentioned bistability and high-speed response are observed when an electric field is applied to the ferroelectric liquid crystal panel. The ferroelectric liquid crystal layer is formed between a pair of transparent electrodes. Therefore, if the thickness of the ferroelectric liquid crystal layer is reduced,
Conduction easily occurs between the pair of transparent electrodes, and when the conduction occurs, the display characteristics deteriorate. Therefore, in order to obtain a ferroelectric liquid crystal panel having good display characteristics, it is necessary to prevent conduction between the pair of transparent electrodes.

In the conventional ferroelectric liquid crystal panel, the ferroelectric liquid crystal is normally aligned by using an alignment film formed by a rubbing method or an oblique vapor deposition method. Since this alignment film has an electrical insulating property, it is possible to prevent the above conduction by increasing the film thickness to a certain degree, but on the other hand, since it causes a voltage drop in the alignment film, it is ferroelectric. The voltage applied to the liquid crystal layer is reduced, and the bistability of the panel is reduced.

A ferroelectric liquid crystal panel which prevents the above conduction without impairing the bistability is disclosed in JP-A-64-3.
A liquid crystal element disclosed in Japanese Patent No. 3526 is known. In this liquid crystal element, a dielectric layer having a two-layer structure is formed between at least one of a pair of transparent electrodes and a liquid crystal layer. The dielectric layer is composed of a first layer (upper and lower short prevention layer) provided on the transparent electrode and a second layer (alignment control layer) provided on the first layer. It is made of a substance having a dielectric constant or a ferroelectric substance. Also,
The second layer is made of a low resistance dielectric, and the surface of the second layer in contact with the liquid crystal layer is uniaxially oriented by a rubbing method or an oblique evaporation method.

By the way, in recent years, a method for orienting a ferroelectric liquid crystal by applying a shearing force while applying an electric field to the ferroelectric liquid crystal has been developed (JP-A-3-5727). Refer to the official gazette. Hereinafter, this method is referred to as a roll orientation method.). According to this roll alignment method, it is possible to obtain a uniform liquid crystal alignment layer with a large area in an extremely short time.

[0007]

The above-mentioned two-layer structure dielectric layer is useful for preventing conduction between a pair of transparent electrodes without impairing the bistability of the element.
Since it has a two-layer structure, it has a drawback that the manufacturing process is complicated. Further, in the alignment treatment based on the roll alignment method described above, a relatively high voltage of 50 to 70 V is applied between a pair of transparent electrodes facing each other through the ferroelectric liquid crystal layer. When conduction occurs between the pair of transparent electrodes, defective orientation (conduction defect) occurs. And
In order to prevent the above-mentioned orientation failure by covering the transparent electrode with an electric insulating film made of a conventional material, the film thickness of the electric insulating film must be made relatively large. Bistability of the liquid crystal panel becomes low.

A first object of the present invention is to provide an electric insulating film which is easy to form and has both conductivity and dielectric properties. A second object of the present invention is to prevent conduction between a pair of transparent electrodes facing each other via a ferroelectric liquid crystal layer, and to align the ferroelectric liquid crystal by a roll alignment method in the manufacturing process. It is an object of the present invention to provide a ferroelectric liquid crystal panel which can obtain a good bistability.

[0009]

The electrical insulating film of the present invention which achieves the first object is a substance having a specific resistance of 1 × 10 ⁸ Ω · cm in a polymer compound having a relative dielectric constant of 15 or more. Conductive fine particles are dispersed and have a specific resistance of 1 × 10
It is characterized in that the film has a relative dielectric constant of 10 or more and a film thickness of 0.20 μm or more in the range of ^{2 to} 5 × 10 ⁹ Ω · cm.

Further, the ferroelectric liquid crystal panel of the present invention which achieves the above second object, has two electric insulating films facing each other and a ferroelectric liquid crystal layer formed between the two electric insulating films. And the electrical insulating film is the above-described electrical insulating film of the present invention, and the electrical insulating film is formed on at least one main surface of the substrate through at least a transparent electrode. Is.

The present invention will be described in detail below. First, the electrical insulating film of the present invention will be described. The electrical insulating film is made of a polymer compound having a relative dielectric constant of 15 or more and a specific resistance of 1 × 1.
0 ⁸ Ω · cm by dispersing conductive fine particles made of the following materials composed. Here, the relative permittivity referred to in the present invention is ASTM-
It means the value measured based on D150, and the specific resistance is AS
It means a value measured based on TM-D257.

The relative permittivity of the polymer compound is 15 or more, preferably 17 or more. Specific examples of such polymer compounds include cyanoethyl pullulan (relative permittivity: 17) and cyanoethyl amylose (see 1 above).
7), cyanoethyl cellulose (the same 17), cyanoethyl polyacrylamide (the same 20), cyanoethyl polyacrylate (the same 20), cyanoethyl saccharose (the same 32), cyanoethyl polyvinyl alcohol (the same 1)
7), polyvinylidene fluoride (15), and polyvinylidene fluoride-trifluoroethylene copolymer (1)
7) etc. are mentioned.

The specific resistance of the raw material for the conductive fine particles is 1 × 10 ⁸ Ω · cm or less, but 10 Ω · cm.
The following is preferred. Specific examples of such a raw material include ITO (tin-doped indium oxide; specific resistance <
1 Ω · cm), TiO ₂ (titania; same <1 Ω · c
m), ATO (antimony-doped indium oxide;
1 Ω · cm), SnO ₂ (tin oxide; same <1 Ω · cm),
Sb-doped SnO ₂ (same <1Ω · cm), ZnO (zinc oxide; same <1Ω · cm), Ag (same <1Ω · cm), A
Examples thereof include u (the same <1 Ω · cm) and Pt (the same <1 Ω · cm). The average particle diameter of the conductive fine particles is preferably 0.1 μm or less, and particularly preferably 0.05 μm or less, from the viewpoint of obtaining an electric insulating film having a substantially smooth film surface.

The electrical insulating film of the present invention has a specific resistance in the range of 1 × 10 ^{2 to} 5 × 10 ⁹ Ω · cm and a relative permittivity by dispersing the above-mentioned conductive fine particles in the above-mentioned polymer compound. Is 10 or more. If either the specific resistance or the relative dielectric constant deviates from the above range, electrical insulation useful for obtaining a ferroelectric liquid crystal panel with good bistability (a liquid crystal in which a ferroelectric liquid crystal is aligned by the roll alignment method) is obtained. It becomes difficult to obtain a film. The specific resistance of the electric insulation film is 1 × 10 ^2.
Is within the range of 5 × 10 ⁹ Ω · cm, but 1 × 10 ⁵
It is preferably in the range of 1 × 10 ⁸ Ω · cm. The relative dielectric constant of the electric insulating film is 10 or more, preferably 20.
That is all.

The thickness of the electric insulating film of the present invention is 0.2.
It is limited to 0 μm or more. When the thickness is less than 0.20 μm, an alignment defect (conduction defect) is likely to occur when the ferroelectric liquid crystal is aligned by the roll alignment method in the process of manufacturing the ferroelectric liquid crystal panel using this electric insulating film. The thickness of the electric insulating film varies depending on the use of the electric insulating film, but when used in a ferroelectric liquid crystal panel (a liquid crystal in which a ferroelectric liquid crystal is aligned by a roll alignment method) is 0.20 to 2 μm. Is preferably in the range of 0.20 to 0.50 μm
It is particularly preferable to set it within the range. When the electric insulating film of the present invention is used in a ferroelectric liquid crystal panel, if the electric insulating film has a thickness of more than 2 μm, it becomes difficult to obtain a ferroelectric liquid crystal panel having a practically sufficient light transmittance. Become.

The content of the conductive fine particles in the electric insulating film of the present invention varies depending on what is used as the conductive fine particles and the polymer compound, but is 20 to 80 wt.
It is preferably within the range of%. When the content of the conductive fine particles is less than 20 wt%, it is difficult to obtain an electric insulating film having a desired specific resistance. Further, if the content of the conductive fine particles exceeds 80 wt%, the mechanical strength of the obtained film will be too low. Content of conductive fine particles is 40-60 wt
It is more preferable to set it within the range of%. Only one type of conductive fine particles may be dispersed in the polymer compound, or 2
It may be more than one species.

The electrical insulating film of the present invention described above can be manufactured, for example, as follows. First, a polymer compound and conductive fine particles are added to an appropriate solvent (which dissolves the polymer compound) such as 2-butanone, methyl isobutyl ketone, toluene, acetone, and methanol, and a dispersion device such as an ultrasonic homogenizer is added. A coating solution is prepared by dissolving the polymer compound in a solvent and dispersing the conductive fine particles. next,
The coating solution is applied to a desired substrate by a method such as a spin coating method, a roll coating method, or a spray coating method to form a uniform coating film. The roll coating method is suitable for continuous coating on a long plastic substrate or the like. After that, the base material on which the coating film is formed is placed in a heating device such as a clean oven to be heat-treated,
Solvent is dried and solidified. The heat treatment conditions at this time are appropriately set according to the type of solvent and the type of polymer compound. By carrying out this heat treatment, the intended electrical insulating film can be obtained.

The electrical insulating film of the present invention thus obtained has a high dielectric property and a relatively high conductivity. The electric insulating film of the present invention having such characteristics is an electric insulating film for preventing conduction between a pair of transparent electrodes facing each other via a ferroelectric liquid crystal layer in a ferroelectric liquid crystal panel. In particular, as an electrical insulating film for preventing conduction between the pair of transparent electrodes when a ferroelectric liquid crystal panel is obtained by orienting a ferroelectric liquid crystal by a roll orientation method. Is. When a ferroelectric liquid crystal panel is manufactured by using the electric insulating film of the present invention, it is possible to obtain a liquid crystal panel having good bistability. The electric insulating film of the present invention is also useful as an electric insulating film for applications such as a spatial light modulator.

Next, the ferroelectric liquid crystal panel of the present invention will be described. As described above, this ferroelectric liquid crystal panel includes two electric insulating films facing each other and the ferroelectric liquid crystal layer formed between these two electric insulating films. The film is formed on at least one main surface of the substrate via at least the transparent electrode. The electric insulating film forming the ferroelectric liquid crystal panel is the electric insulating film of the present invention described above.

In the ferroelectric liquid crystal panel of the present invention,
Members other than the electric insulating film are not particularly limited, and members made of various materials conventionally used as materials for ferroelectric liquid crystal panels can be used. For example, the material of the substrate may be glass or plastic. When manufacturing a ferroelectric liquid crystal panel with high productivity, the thickness is 0.05 to 0.5 mm.
It is preferable to use the above plastic film as the substrate. Specific examples of plastics in this case include uniaxially stretched PET (polyethylene terephthalate) and biaxially stretched PET for crystalline polymers, and PE (polyethylene), PP (polypropylene), PES (polyether) for amorphous polymers. Sulfone) and PA
r (polyarylate) and the like can be mentioned. The ferroelectric liquid crystal panel has two substrates, but at least one of the substrates is optically transparent, that is, has a visible light transmittance of 60% or more. .

As the material of the transparent electrode interposed between the substrate and the electric insulating film, a material having both conductivity and transparency is used. Specific examples include ITO and SnO ₂ . The shape of the transparent electrode is appropriately selected according to the intended use and driving method of the ferroelectric liquid crystal panel.

For example, when manufacturing a ferroelectric liquid crystal panel for a simple matrix type liquid crystal display device, a pair of transparent electrodes facing each other via a ferroelectric liquid crystal layer and an electric insulating film are formed. The directions of the transparent electrodes are determined so that the pair of transparent electrodes are formed in a stripe shape and are orthogonal to each other when viewed in a plan view.

TFT (Thin Film Transistor) -When manufacturing a ferroelectric liquid crystal panel for an active matrix type liquid crystal display device, a pair of transparent electrodes facing each other with a ferroelectric liquid crystal layer and an electric insulating film interposed therebetween. One of the two is formed into a pixel electrode having a shape and arrangement pattern corresponding to the shape and arrangement pattern of pixels, and a TFT is connected to each pixel electrode. The other transparent electrode (common electrode) of the pair of transparent electrodes is formed in one film shape having a size capable of covering all the pixel electrodes arranged in the predetermined pattern in plan view.

When manufacturing a ferroelectric liquid crystal panel for a diode-active matrix type liquid crystal display device, a pair of transparent electrodes facing each other with a ferroelectric liquid crystal layer and an electric insulating film interposed therebetween. One of them is formed into a pixel electrode having a shape and arrangement pattern corresponding to the shape and arrangement pattern of pixels, and a diode is connected to each pixel electrode. The other transparent electrode (signal electrode) of the pair of transparent electrodes is formed in a stripe shape along the arrangement direction of the pixel electrodes arranged in the predetermined pattern.

As the material of the ferroelectric liquid crystal layer, ferroelectric polymer liquid crystal, a mixture of ferroelectric polymer liquid crystal and other polymer liquid crystal, ferroelectric polymer liquid crystal and ferroelectric low molecule are used. It is possible to use a mixture with liquid crystal, a mixture of ferroelectric high-molecular liquid crystal, ferroelectric low-molecular liquid crystal and high-molecular liquid crystal, or a mixture of these with a normal low-molecular liquid crystal. As the ferroelectric polymer liquid crystal, a side chain type ferroelectric polymer liquid crystal having a chiral smectic C phase is suitable. When the ferroelectric polymer liquid crystal and the ferroelectric low-molecular liquid crystal (including the low-molecular liquid crystal when the normal low-molecular liquid crystal is used together) are used together, the mixing ratio of the both is 95: 5 to 20:80
Is preferably within the range of 80:20 to 40: 6
More preferably, it is within the range of 0. The above-mentioned ferroelectric polymer liquid crystal, polymer liquid crystal, ferroelectric low-molecular liquid crystal and low-molecular liquid crystal may each be one kind alone, or may be a mixture of two or more kinds. If necessary, the material of the ferroelectric liquid crystal layer may contain an adhesive, a viscosity reducing agent, an amorphous chiral compound, a dye, a non-liquid crystal polymer substance, or the like.

Among the above-mentioned ferroelectric polymer liquid crystals, homopolymers include, for example, acrylate main chain liquid crystal polymers, methacrylate main chain liquid crystal polymers, chloroacrylate main chain liquid crystal polymers, oxirane main chain liquid crystal polymers. , A siloxane main chain liquid crystal polymer, an ester main chain liquid crystal polymer, and a siloxane-olefin main chain liquid crystal polymer. Specific examples of the acrylate main chain liquid crystal polymer include, for example, repeating units

Embedded image

Embedded image The items shown in are listed.

As specific examples of the above-mentioned methacrylate main chain type liquid crystal polymer, for example, a repeating unit is

[Chemical 3]

[Chemical 4] The items shown in are listed.

Specific examples of the above chloroacrylate main chain liquid crystal polymer include, for example, repeating units:

Embedded image The items shown in are listed.

Specific examples of the oxirane main chain liquid crystal polymer include, for example, repeating units

[Chemical 6]

[Chemical 7] The items shown in are listed.

Specific examples of the siloxane main chain type liquid crystal polymer include, for example, repeating units:

Embedded image The items shown in are listed.

Specific examples of the above ester main chain type liquid crystal polymer include, for example, repeating units:

[Chemical 9]

[Chemical 10]

[Chemical 11] The items shown in are listed.

As specific examples of the above-mentioned siloxane-olefin main chain type liquid crystal polymer, for example, a repeating unit is

[Chemical 12]

[Chemical 13] The items shown in are listed.

In the repeating unit of the above ferroelectric liquid crystal polymer, the side chain skeleton may be replaced with a biphenyl skeleton, a phenylbenzoate skeleton, a biphenylbenzoate skeleton, or a phenyl 4-phenylbenzoate skeleton. The benzene ring in these skeletons may be replaced with a pyrimidine ring, a pyridine ring, a pyridazine ring, a pyrazine ring, a tetrazine ring, a cyclohexane ring, a dioxane ring, or a dioxaborinane ring, and a halogen group such as fluorine or chlorine or a cyano group. May be substituted with a group, 1-methylalkyl group, 2-fluoroalkyl group,
2-chloroalkyl group, 2-chloro-3-methylalkyl group, 2-trifluoromethylalkyl group, 1-alkoxycarbonylethyl group, 2-alkoxy-1-methylethyl group, 2-alkoxypropyl group, 2-chloro -1
-Methylalkyl group, 2-alkoxycarbonyl-1-
It may be replaced with an optically active group such as a trifluoromethylpropyl group. Further, the length of the spacer may be changed within the range of 2 to 30 in methylene chain length. The number average molecular weight of the ferroelectric liquid crystal polymer is 1,000 to 200,000.
It is preferably in the range of 0.

On the other hand, examples of the ferroelectric low-molecular liquid crystal include Schiff base type ferroelectric low-molecular liquid crystal compound, azo and azoxy type ferroelectric low-molecular liquid crystal compounds, biphenyl and aromatic ester type ferroelectric low-molecular liquid crystal. Examples thereof include compounds, ferroelectric low-molecular liquid crystal compounds having a ring substituent such as halogen or cyano group, and ferroelectric low-molecular liquid crystal compounds having a heterocycle. Examples of the Schiff base ferroelectric low-molecular liquid crystal compound include the following compounds.

[0035]

Embedded image

[Chemical 15]

Embedded image

[Chemical 17]

Examples of the above-mentioned azo and azoxy type ferroelectric low molecular weight liquid crystal compounds include the following compounds.

Embedded image

[Chemical 19]

Examples of the above-mentioned biphenyl and aromatic ester-based ferroelectric low molecular weight liquid crystal compounds include the following compounds.

Embedded image

[Chemical 21]

Examples of the ferroelectric low molecular weight liquid crystal compound into which the ring substituent such as halogen or cyano group is introduced include the following compounds.

[Chemical formula 22]

[Chemical formula 23]

[Chemical formula 24]

Examples of the ferroelectric low molecular weight liquid crystal compound having the above heterocycle include the following compounds.

[Chemical 25]

[Chemical formula 26] The above-mentioned compounds are representative of the ferroelectric low-molecular liquid crystal compounds, and the ferroelectric low-molecular liquid crystal compounds usable as the material of the ferroelectric liquid crystal layer in the present invention are not limited to the above compounds. Not something.

The ferroelectric liquid crystal panel of the present invention can be manufactured, for example, as follows. First, a transparent conductive film as a material of a transparent electrode is formed on one surface of a predetermined substrate by a method such as a vacuum deposition method or a sputtering method, and then this transparent conductive film is formed into a predetermined shape by a photolithography method or the like. Next, the electrically insulating film of the present invention is formed on the transparent electrode so as to cover the transparent electrode by the method described above. In this way, a total of two substrates each having an electric insulating film formed on the transparent electrode are prepared. Then, the liquid crystal layer coating solution is applied onto the electrical insulating film of one of the substrates using a gravure coater or the like to form a uniform coating film. The liquid crystal layer coating solution can be prepared by dissolving the above-mentioned ferroelectric liquid crystal layer material in a solvent such as 2-butanone, toluene, cyclohexanone, or acetone. Next, the substrate on which the coating film is formed is placed in a heating device such as a clean oven to be heat-treated to dry the solvent. The liquid crystal layer is formed by this heat treatment. The thickness of the liquid crystal layer at this stage is preferably in the range of 1 to 10 μm, more preferably 1.5 to 3 μm. Next, the substrate on which the liquid crystal layer was not formed (the one on which the electric insulating film was formed) was placed on the substrate on which the liquid crystal layer was formed so that the electric insulating layer of the substrate was in contact with the liquid crystal layer. They are stacked and laminated with a pair of pressure rollers to obtain a laminate. After that, the ferroelectric liquid crystal in the ferroelectric liquid crystal layer constituting the above-mentioned laminate is aligned by the roll alignment method. As a result, the desired ferroelectric liquid crystal panel can be obtained.

When the ferroelectric liquid crystal panel of the present invention is used as a liquid crystal panel of a color liquid crystal display device, for example, one of the two substrates constituting the panel is red, blue and blue. A green micro color filter is provided, a transparent electrode is formed, and an electrically insulating layer is formed on the transparent electrode. Further, the method of aligning the ferroelectric liquid crystal in producing the ferroelectric liquid crystal panel of the present invention is not limited to the roll aligning method.

In the ferroelectric liquid crystal panel of the present invention obtained as described above, since the electric insulating film constituting the ferroelectric liquid crystal panel has a high electric insulation property, a pair of transparent electrodes facing each other with the ferroelectric liquid crystal layer interposed therebetween. Conduction is prevented from occurring between the electrodes. Even when the ferroelectric liquid crystal is oriented by the roll orientation method, the electrical insulating film prevents conduction between the pair of transparent electrodes facing each other through the ferroelectric liquid crystal layer. , Alignment failure (conduction defect) hardly occurs. Therefore, when the ferroelectric liquid crystal panel of the present invention is used as a liquid crystal panel for a liquid crystal display device,
A liquid crystal display device having good display characteristics can be obtained.

Further, since the electric insulating film constituting the ferroelectric liquid crystal panel of the present invention has relatively high conductivity,
The voltage drop due to the presence of this electric insulating film is small. Therefore, the bistability of the ferroelectric liquid crystal panel of the present invention is good.

The ferroelectric liquid crystal panel of the present invention having such characteristics is suitable as a liquid crystal panel for a liquid crystal display device, and is also useful as a spatial modulation element or the like.

[0045]

Embodiments of the present invention will be described below. Example 1 (1) Formation of Electrical Insulating Film First, a stripe-shaped ITO electrode (film thickness = thickness) extending on the one side of a polyethersulfone film (Sumitomo Bakelite Co., Ltd .; 60 × 15 cm, thickness 100 μm) extending in the longitudinal direction of the film. 0.1 μm, width of one electrode = 1.07 m
m, electrode gap 0.2 mm, area resistance = 300 Ω ・ c
m) formed (hereinafter referred to as "base material A"),
A striped ITO electrode (thickness = 0.1 µm, width of one electrode = 1) extending in the lateral direction of the film on one surface of a polyether sulfone film (Sumitomo Bakelite Co., Ltd .; 60 x 15 cm, thickness 100 µm) 0.07, electrode gap 0.2 mm, area resistance = 300 Ω · cm) (hereinafter referred to as base material B) were prepared. In addition, cyanoethyl pullulan (A-Grade 0 manufactured by Nippon Kasei Co., Ltd.) was used as a polymer compound for an electric insulating film.
1; relative permittivity 17) was prepared, and Sb-doped SnO ₂ fine particles (T-1 manufactured by Mitsubishi Materials Corp.) having an average particle diameter of 0.02 μm and a specific resistance of 3 Ω · cm as conductive fine particles for an electric insulating film. The shape of each fine particle was spherical.

Next, 1 part by weight of the above polymer compound and 1 part by weight of the above conductive fine particles are added to 2-butanone, and the polymer compound is dissolved in 2-butanone using an ultrasonic homogenizer. A coating solution was prepared by dispersing the conductive fine particles in 2-butanone (the total amount of the polymer compound and the conductive fine particles in the coating solution was 10 wt%). Next, this coating solution is applied to the ITO electrode of the base material A using a gravure roll coater, and also applied to the ITO electrode of the base material B using a gravure roll coater, and these are cleaned at 130 ° C. The solvent was dried by heating in an oven for 30 minutes. As a result, the IT of the base material A
An electric insulating film was formed on each of the O electrode and the ITO electrode of the base material B. As a result of electron microscopic observation, the thickness of each of these electric insulating films was 0.46 μm. Moreover, the specific resistance of these electric insulating films is 3.0 ×.
It was 10 ⁸ Ω · cm, and the relative dielectric constants were both 14.

(2) Preparation of Ferroelectric Liquid Crystal Display Element First, the following formula (i) is used as a material for the ferroelectric liquid crystal layer.

[Chemical 27] Liquid crystal represented by (number average molecular weight Mn = 2700) and the following formula (ii)

[Chemical 28] A mixture with a liquid crystal (P1008 manufactured by Midori Kagaku Co., Ltd.) (mixing ratio: former: latter = 80: 20 (weight ratio)) was used and dissolved in methyl ethyl ketone to prepare a coating solution (strong). The concentration of the dielectric liquid crystal is 30
weight%).

The phase transition temperatures of the above liquid crystals (i) and (ii) are as follows.

[Equation 1]

Then, the above-mentioned coating solution was applied onto the electric insulating film formed on the ITO electrode of the substrate A in the above (1) using a gravure roll coater, and this was applied to 130
It was heated in a clean oven at 0 ° C. for 20 minutes to dry the solvent. As a result, a ferroelectric liquid crystal layer was formed on the electric insulating film formed on the ITO electrode of the base material A.

Next, the base material A on which the ferroelectric liquid crystal layer is formed
And a base material B having an electric insulation layer formed thereon are laminated by a pressure roll so that the ferroelectric liquid crystal layer formed on the base material A and the electric insulation layer formed on the base material B are in contact with each other, A laminate was obtained. The film thickness of the ferroelectric liquid crystal layer in this laminate was 2 μm.

Then, a DC voltage of 60 V was applied between the upper and lower ITO electrodes (ITO electrode on the base material A and ITO electrode on the base material B) of the above-mentioned laminate at room temperature, and the whole laminate was applied. The ferroelectric liquid crystal was oriented by a method of flexural deformation in a certain direction. More specifically, as shown in FIG. 1, the upper and lower ITO electrodes of the laminate 1 and the power source 2 are connected by two lead wires 3a and 3b, and the upper and lower ITO electrodes are connected at room temperature. While applying a DC voltage of 60V, the pair of rolls 4a, 4 are formed so that the laminate 1 has an S-shaped mirror image when viewed from the side.
By moving between b at a speed of 1 m / min (the moving direction is indicated by an arrow in the figure), a shearing force due to bending deformation is applied to the laminate 1, whereby the ferroelectric liquid crystal is oriented. . By carrying out this alignment treatment, a ferroelectric liquid crystal panel having a sectional structure shown in FIG. 2 was obtained. As shown in the figure, the ferroelectric liquid crystal panel 11 has ITO on one side.
Two polyether sulfone films 14 in which the electrode 12 and the electric insulating layer 13 are sequentially laminated are arranged so as to face each other with the electric insulating layer 13 inside.
A ferroelectric liquid crystal layer 15 that has been oriented is formed between the two electric insulating layers 13.

(3) Evaluation of bistability The ferroelectric liquid crystal panel prepared in the above (2) is placed between two neutral polarizing plates whose polarization axes are orthogonal to each other,
After making a dark state when a positive voltage is applied,
The bistability of this ferroelectric liquid crystal panel was investigated by the method described below.

First, a single-shot rectangular wave voltage (pulse width 1 ms, ± 30 V) as shown in FIG. 3A is applied to write a bright state to the ferroelectric liquid crystal panel, and the single-shot rectangular wave is applied. The transmitted light intensity S _B (2) after 2 milliseconds and the transmitted light intensity S _B (192) after 192 milliseconds are measured. The change in transmitted light intensity after application of the single rectangular wave is approximately as shown in FIG. In addition, a single rectangular wave voltage (pulse width 1 ms, ± 30 V) as shown in FIG. 4A is applied to write a dark state in the ferroelectric liquid crystal panel, and 2 ms after the single rectangular wave is applied. The transmitted light intensity S _D (2) after and the transmitted light intensity S _D (192) after 192 ms are measured. The change in the transmitted light intensity after the application of the single rectangular wave is approximately as shown in FIG.

After this, S _B (2), S _B (192), S _B
From the values of _D (2) and S _D (192),

[Equation 2] Was calculated, and the stability of the bright state and the dark state (bistability) was investigated from the value of M. Table 1 shows the results. The larger the value of M, the higher the bistability.

In addition, the number of alignment defects (conduction defects) of the liquid crystal caused by the conduction between the two ITO electrodes during roll alignment and the voltage drop across the ferroelectric liquid crystal layer is determined by the ferroelectric liquid crystal panel. 30 × 15c on the ferroelectric liquid crystal panel in a state where it is placed between two neutral polarizing plates.
The area of m was counted by visual observation. The results are also shown in Table 1.

Comparative Examples 1 to 3 In preparing a coating solution for producing an electric insulating film, conductive fine particles were not added, and the proportion of the polymer compound in the coating solution was compared as shown in Table 1. Ferroelectric liquid crystal panels were manufactured under the same conditions as in the examples except that the amount was 3 wt%, 5 wt%, or 10 wt% for each example. About these ferroelectric liquid crystal panels,
Bistability and the number of orientation defects were examined under the same conditions as in Example 1. Table 1 shows the results.

Comparative Examples 4 to 5 In preparing a coating solution for producing an electric insulating film, the ratio of the total amount of the polymer compound and the conductive fine particles in the coating solution is shown in Table 1 for each comparative example. 5 wt
% Or 10 wt%, ferroelectric liquid crystal panels were produced under the same conditions as in the examples. With respect to these ferroelectric liquid crystal panels, bistability and the number of alignment defects were examined under the same conditions as in Example 1. Table 1 shows the results.

Examples 2 to 3 As conductive fine particles, ITO fine particles having a particle diameter in the range of 0.03 to 0.1 μm and a specific resistance of 0.009 Ω · cm (ITO-UFP manufactured by Sumitomo Metal Mining Co., Ltd.) ), And in preparing a coating solution for preparing an electric insulating film, the total proportion of the polymer compound and the conductive fine particles in the coating solution is 5 wt% or 10 wt% for each example as shown in Table 1. Other conditions were the same as those of the example, and the ferroelectric liquid crystal panels were manufactured. With respect to these ferroelectric liquid crystal panels, bistability and the number of alignment defects were examined under the same conditions as in Example 1. Table 1 shows the results.

Comparative Examples 6 to 8 In preparing a coating solution for preparing an electric insulating film, conductive fine particles were not added, and the proportion of the polymer compound in the coating solution was compared as shown in Table 1. Ferroelectric liquid crystal panels were manufactured under the same conditions as in the examples except that the amount was 3 wt%, 5 wt%, or 10 wt% for each example. About these ferroelectric liquid crystal panels,
Bistability and the number of orientation defects were examined under the same conditions as in Example 1. Table 1 shows the results.

Comparative Example 9 Ferroelectric properties were obtained under the same conditions as in Example 1 except that the total amount of the polymer compound and the conductive fine particles in the coating solution was 3 wt% in preparing the coating solution for preparing the electric insulating film. A liquid crystal panel was produced. With respect to this ferroelectric liquid crystal panel, bistability and the number of alignment defects were examined under the same conditions as in Example 1. Table 1 shows the results.

[0061]

[Table 1]

As shown in Table 1, Examples 1 to 3
Each of the electric insulating films produced in step 1 has high dielectric properties and relatively high conductivity. And Example 1-
Each of the ferroelectric liquid crystal panels manufactured in Example 3 has good bistability, and there is substantially no alignment defect (conduction defect) of the ferroelectric liquid crystal. On the other hand, among the ferroelectric liquid crystal panels obtained in Comparative Examples 1 to 3 and Comparative Examples 6 to 8 in which the conductive fine particles were not dispersed in the electric insulating film, Comparative Example 1 and Comparative Example 6 Each of the ferroelectric liquid crystal panels of No. 1 had good bistability, but in these panels, defective alignment (conduction defect) of the ferroelectric liquid crystal was observed. Further, in each of the ferroelectric liquid crystal panels of Comparative Example 3 and Comparative Example 8, no alignment defect (conduction defect) of the ferroelectric liquid crystal was observed, but these panels have extremely low bistability. Each of the ferroelectric liquid crystal panels of Comparative Example 2 and Comparative Example 7 had low bistability, and in these panels, defective alignment (conduction defect) of the ferroelectric liquid crystal was observed.

Comparative Example 4 provided with an electric insulating film having the same composition as the electric insulating film produced in Example 1 but having a small film thickness.
Each ferroelectric liquid crystal panel of Comparative Example 5 has almost the same bistability as that of the ferroelectric liquid crystal panel of Example 1, but in these panels, the ferroelectric liquid crystal has poor alignment (conduction). (Defect) was recognized. Then, the ferroelectric liquid crystal panel of Comparative Example 9 including the electric insulating film having the same composition as that of the electric insulating film manufactured in Examples 2 to 3 and having a thin film thickness is the ferroelectric liquid crystal panel of Example 2 to Example 3. Although it has almost the same bistability as a ferroelectric liquid crystal panel, a large number of defective alignments (conduction defects) of the ferroelectric liquid crystal were observed in this panel.

[0064]

As described above, the electrical insulating film of the present invention is easy to form and has both conductivity and dielectric property. Further, in the ferroelectric liquid crystal panel of the present invention using this electric insulating film, conduction is unlikely to occur between a pair of transparent electrodes facing each other via the ferroelectric liquid crystal layer, and the roll alignment method is used in the manufacturing process. As a result, even if the ferroelectric liquid crystal is oriented, a good bistability can be obtained. Therefore, according to the present invention, a ferroelectric liquid crystal panel having good display characteristics and good bistability can be easily manufactured with high productivity.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a method of aligning a ferroelectric liquid crystal in Example 1.

FIG. 2 is a cross-sectional view schematically showing a ferroelectric liquid crystal panel manufactured in Example 1.

3A is a diagram showing a single-shot rectangular wave used to write a bright state to a ferroelectric liquid crystal panel in Example 1, and FIG. 3B is a change in transmitted light intensity after application of a single-shot rectangular wave. 2 is a graph schematically showing

4A is a diagram showing a single-shot rectangular wave used to write a dark state in a ferroelectric liquid crystal panel in Example 1, and FIG. 4B is a change in transmitted light intensity after application of a single-shot rectangular wave. 2 is a graph schematically showing

[Explanation of symbols]

 11 Ferroelectric Liquid Crystal Panel 12 Substrate 13 Transparent Electrode 14 Electrical Insulating Film 15 Oriented Ferroelectric Liquid Crystal Layer

Claims (5)

[Claims] 1. A conductive polymer fine particle made of a substance having a specific resistance of 1 × 10 ⁸ Ω · cm or less is dispersed in a polymer compound having a relative dielectric constant of 15 or more, and the specific resistance is 1 × 10 ² to 5
An electrical insulating film having a relative dielectric constant of 10 or more and a film thickness of 0.20 μm or more in a range of × 10 ⁹ Ω · cm. 2. The content of the conductive fine particles is 20 to 80 wt.
The electrical insulating film according to claim 1, which is in the range of%. 3. The polymer compound is cyanoethyl pullulan,
One or more selected from the group consisting of cyanoethyl amylose, cyanoethyl cellulose, cyanoethyl polyacrylamide, cyanoethyl polyacrylate, cyanoethyl saccharose, cyanoethyl polyvinyl alcohol, polyvinylidene fluoride, and polyvinylidene fluoride-trifluoroethylene copolymer. The electric insulating film according to claim 1 or 2. 4. The conductive fine particles are ITO, TiO ₂ , and AT.
O, SnO ₂ , Sb-doped SnO ₂ , ZnO, Ag, A
consisting of a material selected from the group consisting of u and Pt,
The average particle diameter is 0.1 μm or less, Claims 1 to 3.
The electrical insulating film according to any one of 1. 5. An electric insulating film comprising: two electric insulating films facing each other; and a ferroelectric liquid crystal layer formed between the two electric insulating films, wherein the electric insulating film is any one of claims 1 to 4. 2. A ferroelectric liquid crystal panel, which is the electrical insulating film as described in 1 above, and which is formed on at least one main surface of the substrate via at least a transparent electrode.