JP2016184031A - Alignment film for liquid crystal and reverse mode polymer dispersion type liquid crystal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel alignment film for a liquid crystal, from which a reverse mode polymer dispersion type liquid crystal element can be manufactured by using a general transparent film substrate, the liquid crystal element having similar performances to those of a liquid crystal element using, for example, a vertical alignment film made of a polyimide resin.SOLUTION: The alignment film for a liquid crystal is formed by homeotropically aligning a UV-curable liquid crystal on a transparent electrode formed on a transparent film substrate. More specifically, the alignment film is preferably constituted by applying a mixture prepared by mixing a homeotropic alignment type UV-curable liquid crystal and a UV-curable resin in a ratio of 30:70 to 99:1 on the transparent electrode. By using the novel alignment film for a liquid crystal, a reverse mode polymer dispersion type liquid crystal element can be manufactured.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a novel alignment film for liquid crystal that can be used in a polymer dispersion type liquid crystal element in a reverse mode, and a polymer dispersion type liquid crystal element using the same.

  As a polymer-dispersed liquid crystal element, there are a normal mode that changes from a scattering state to a transparent state when a voltage is applied, and a reverse mode that changes from a transparent state to a scattering state when a voltage is applied.

  In the reverse mode, a liquid crystal material having a negative dielectric anisotropy is dispersed in a resin matrix, and a transparent electrode is formed to align liquid crystal molecules homeotropically when no voltage is applied. An alignment film having a pretilt angle of 90 ° is formed on the substrate.

  Conventionally, a film made of polyimide resin (polyimide film) is used as the alignment film. The polyimide film is formed by applying a polyamic acid solution, which is a polyimide precursor, to a substrate, followed by heat treatment at a temperature of 300 ° C. to 350 ° C. or higher for a long time to dehydrate and ring-close the polyimide film. There is a method of forming. In addition, there is a method of preparing a polyimide film by applying and drying a solution in which a polymer of polyamic acid and polyimide is dissolved in a solvent (for example, Patent Document 1).

  However, in the method for forming a polyimide film, heat treatment for a long time is required as described above, and also in the method for applying and drying a polyimide solution, N-methyl-2-pyrrolidone, γ- Since a high boiling point solvent such as butyrolactone is used, a drying temperature of 180 ° C. to 200 ° C. is required.

  Thus, in forming the polyimide film constituting the alignment film of the reverse mode polymer dispersion type liquid crystal element, a treatment at a high temperature is necessary, and a general film substrate is used as the substrate. It is difficult, and when a film substrate is used, an expensive film substrate such as polyether nitrile or polyether sulfone has to be used.

JP 2002-277880 A

  The present invention has been proposed in view of the above situation, and using a general transparent film substrate, for example, a reverse mode having the same performance as when a vertical alignment film made of a polyimide resin is used. It is an object of the present invention to provide a novel alignment film for liquid crystal capable of producing a polymer-dispersed liquid crystal element.

  This inventor repeated earnest examination in order to solve the subject mentioned above. As a result, a film formed by applying a homeotropic alignment type UV curable liquid crystal material on a transparent film substrate functions as a vertical alignment film for the driving liquid crystal constituting the liquid crystal layer. The headline and the present invention were completed. That is, the present invention provides the following.

  (1) A first aspect of the present invention is an alignment film for liquid crystal, characterized in that an ultraviolet curable liquid crystal is homeotropically aligned on a transparent film substrate.

  (2) According to a second aspect of the present invention, in the first aspect, the homeotropic alignment type ultraviolet curable liquid crystal and the ultraviolet curable resin are provided on the transparent film substrate in a ratio of 30:70 to 99: 1. An alignment film for liquid crystal, which is configured by applying a mixture mixed at a ratio.

  (3) A third aspect of the present invention is an alignment film for liquid crystal, characterized in that ultraviolet curable liquid crystal is homeotropically aligned on a transparent electrode formed on a transparent film substrate.

  (4) According to a fourth aspect of the present invention, in the third aspect, the homeotropic alignment type ultraviolet curable liquid crystal and the ultraviolet curable resin are provided on the transparent electrode in a ratio of 30:70 to 99: 1. An alignment film for liquid crystal, which is formed by applying a mixed mixture.

  (5) The fifth invention of the present invention is a reverse mode polymer dispersion type liquid crystal device using the alignment film for liquid crystal according to the third or fourth invention.

  (6) A sixth aspect of the present invention is a VA mode liquid crystal element using the liquid crystal alignment film according to the third or fourth aspect.

  According to the present invention, a reverse mode molecular dispersion type liquid crystal device having the same performance as that obtained by using a vertical alignment film made of, for example, a conventional polyimide resin can be produced using a general transparent film substrate. .

It is a schematic diagram which shows the structure of the cross section of a polymer dispersion type liquid crystal element. It is a flowchart which shows the flow of the manufacturing process of a polymer dispersion type liquid crystal element. It is the schematic which showed typically the flow of manufacture of a polymer dispersion type liquid crystal element. 6 is a graph showing the relationship between voltage and haze applied to the reverse mode polymer dispersion type liquid crystal elements produced in Example 1, Example 2, and Comparative Example 1. FIG.

  Hereinafter, specific embodiments of the present invention (hereinafter referred to as “present embodiments”) will be described in detail in the following order. In addition, this invention is not limited to the following embodiment, A various change is possible in the range which does not change the summary of this invention.

<< 1. Structure of polymer dispersed liquid crystal element >>
FIG. 1 is a schematic diagram showing a cross-sectional configuration of the polymer dispersed liquid crystal element according to the present embodiment. The polymer dispersed liquid crystal element 1 is a reverse mode type liquid crystal element that changes from a transparent state to a scattering state by applying a voltage.

  Specifically, the polymer dispersed liquid crystal element 1 includes a base film 11, a transparent electrode 12, an alignment film 13, and a liquid crystal layer 14. In this polymer-dispersed liquid crystal element 1, a transparent electrode 12A and an alignment film 13A are sequentially laminated on one base film 11A. Similarly, the transparent electrode 12B and an alignment film are aligned on another base film 11B. The film 13B is sequentially laminated, and the base films 11A and 11B on which the alignment films 13A and 13B are formed are bonded to each other so as to sandwich the liquid crystal layer 14 therebetween.

(1) Base Film The base films 11A and 11B are not particularly limited, and for example, various transparent film materials having flexibility can be used. Specifically, PET, polycarbonate, TAC, COP or the like can be used. Moreover, as thickness of base film 11A, 11B, the thing of 20 micrometers-300 micrometers can be used, for example, and it is preferable that it is a thing of 50 micrometers-150 micrometers especially.

  As will be described in detail later, in the polymer dispersion type liquid crystal element 1 according to the present embodiment, a film formed by applying a homeotropic alignment type ultraviolet curable liquid crystal material to the base films 11A and 11B is used as the alignment film 13A. 13B, so that the driving liquid crystal included in the liquid crystal layer 14 can be appropriately homeotropically aligned in the same manner as a vertical alignment film made of a conventional polyimide resin. Such alignment films 13A and 13B do not require heat treatment at a high temperature unlike conventional polyimide alignment films. Therefore, not only a glass substrate but also a low Tg base film as described above is effective. And a polymer dispersed liquid crystal element having excellent flexibility can be manufactured.

(2) Transparent electrode As the transparent electrodes 12A and 12B, it is possible to apply a substantially uniform electric field to the liquid crystal layer 14 to be described later, and it is possible to apply various configurations that are perceived as transparent. For example, a conductive polymer film, silver nanowires, carbon nanotubes, etc. can be used in addition to metal oxide films such as ITO and IZO which are transparent electrode materials. Although it does not specifically limit as sheet resistance in a transparent electrode material, It is preferable that it is 85% or more as 100-300 ohms / square and the transmittance | permeability.

  In the present embodiment, such a transparent electrode film made of a transparent electrode material can be used by being formed on the entire surface of the transparent base films 11A and 11B described above.

(3) Alignment Film The alignment films 13A and 13B are made of an ultraviolet curable liquid crystal material having a polymerizable functional group and homeotropic alignment. By forming the alignment films 13A and 13B with this ultraviolet curable liquid crystal material, the driving liquid crystal contained in the liquid crystal layer 14 formed on the alignment films 13A and 13B is effectively homeotropic aligned (D direction in FIG. 1). ).

  Here, in a conventional reverse mode polymer dispersed liquid crystal element, a polyimide film is formed as an alignment film on a substrate on which a transparent electrode is formed in order to homeotropically align liquid crystal molecules when no voltage is applied. The pretilt angle was set to 90 °. However, when a polyimide film is used as the alignment film, a heat treatment at a high temperature is required for the coating film, and a general base film such as PET or polycarbonate cannot be used, and a glass substrate or an expensive transparent film is used. It was necessary to use material.

  As a result of extensive studies, the present inventor applied a UV-curable liquid crystal material having homeotropic alignment on a base film, so that the coating film composed of the liquid crystal material is used as a vertical alignment film. I found it to work.

  That is, in the present embodiment, the alignment films 13A and 13B are made of an ultraviolet curable liquid crystal material having a polymerizable functional group and having homeotropic alignment, and the liquid crystal material is homeotropically aligned. ing. According to such a novel liquid crystal alignment film, even when a general film such as PET is used as the base film, the liquid crystal (hereinafter referred to as alignment films 13A and 13B) that appropriately constitutes the liquid crystal layer 14 when no voltage is applied. The liquid crystal material in the liquid crystal layer 14 can be homeotropically aligned so that it can be suitably used as a polymer dispersion type liquid crystal element in a reverse mode.

  Specifically, the liquid crystal material constituting the alignment films 13A and 13B may be composed of a liquid crystal mixture including an ultraviolet curable liquid crystal material having homeotropic alignment, a polymerizable monomer, and a photopolymerization initiator. it can.

(Liquid crystal material)
The liquid crystal material included in the liquid crystal mixture is not particularly limited as long as it is ultraviolet curable (ultraviolet curable liquid crystal) and can form homeotropic alignment without using a vertical alignment film. Absent. For example, a side-chain liquid crystal polymer containing a monomer unit containing a liquid crystalline fragment side chain having a positive refractive index anisotropy and a monomer unit containing a non-liquid crystalline fragment side chain, or a liquid crystalline fragment side chain And a liquid crystal polymer such as a side-chain liquid crystal polymer containing a monomer unit containing a monomer unit containing a liquid crystal fragment side chain having an alicyclic ring structure. Moreover, the liquid crystal material generally used for a VA liquid crystal cell can be used.

  Examples of such a liquid crystal polymer include compounds described in JP2003-121853A, JP2002-174725A, and JP2005-70098A.

(UV curable resin)
As the ultraviolet curable resin, a resin having a monofunctional or polyfunctional polymerizable monomer (polymerizable group) can be used. For example, monofunctional (meth) acrylates such as methyl (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta Polyfunctional (meth) acrylates such as (meth) acrylate and dipentaerythritol hexa (meth) acrylate are exemplified. In addition, the description with (meth) acrylate means an acrylate or a methacrylate. In addition to acrylics, cation polymerizable monomers include alicyclic epoxides such as 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate, and glycidyl ethers such as bisphenol A diglycidyl ether. And the like. These polymerizable monomers can be used singly or in combination of two or more depending on required performance, coating suitability and the like.

  For example, specific examples of the ultraviolet curable resin include a photocurable aliphatic urethane resin, a photocurable aromatic urethane resin, a photocurable acrylic resin, and a photocurable urethane (meth) acrylate.

  Here, the mixing ratio of the liquid crystal material (ultraviolet curable liquid crystal) and the ultraviolet curable resin in the liquid crystal mixture is not particularly limited, but liquid crystal material: UV curable resin = 30: 70 to 99: 1. It is preferable to mix so that it may become a ratio. By applying the liquid crystal mixture obtained by mixing at such a ratio to the base films 11A and 11B, a good homeotropic alignment is exhibited, and the driving liquid crystal contained in the liquid crystal layer 14 is more effectively homeotropic. Can be oriented.

(Photopolymerization initiator)
As the photopolymerization initiator, general photopolymerization initiators can be used. For example, benzoin and its alkyl etherified products, benzyl ketals, acetophenones, and acetophenones include, for example, hydroxyacetophenone, aminoacetophenone, diester. Alkoxyacetophenone, halogenated acetophenone, and the like can be used. As these photopolymerization initiators, for example, products such as Irgacure 907, Irgacure 651, and Irgacure 184 are commercially available, and these can be used alone or in combination.

(solvent)
The liquid crystal mixture described above is usually dissolved in a solvent (dilution solvent). The solvent is not particularly limited as long as the liquid crystal mixture can be uniformly dispersed. For example, hydrocarbon solvents such as benzene and hexane, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone (CHN). , Tetrahydrofuran, 1,2-dimethoxyethane, ether solvents such as propylene glycol monoethyl ether (PGME), alkyl halide solvents such as chloroform and dichloromethane, methyl acetate, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate ( Ester solvents such as PGMEA), amide solvents such as N, N-dimethylformamide, sulfoxide solvents such as dimethyl sulfoxide, anone solvents such as cyclohexane, methanol, ethanol, isopropyl It can be exemplified an alcohol solvent such as alcohol, but is not limited thereto. Moreover, one type of solvent may be single and 2 or more types of mixed solvents may be sufficient as it. In addition, as a quantity of a solvent, it can be set as about 66 mass parts-950 mass parts with respect to 100 mass parts of liquid crystal mixtures, for example.

(Other)
In addition, in the liquid crystal mixture constituting the alignment films 13A and 13B, a leveling agent, a polymerization inhibitor, or the like can be appropriately used in addition to the above-described materials.

(4) Liquid Crystal Layer The liquid crystal layer 14 is a layer that is sandwiched between the alignment films 13A and 13B described above, and is used to form a liquid crystal layer on the alignment film 13A formed on one base film 11A. After coating the coating liquid, it is produced by drying and solidifying.

  In the reverse mode type polymer dispersed liquid crystal element 1, the drive liquid crystal contained in the liquid crystal layer 14 is vertically aligned (homeotropic alignment, direction D in FIG. 1) when no voltage is applied. By applying a voltage between 12A and 12B (at the time of voltage application), the driving liquid crystal is made horizontal alignment (homogeneous alignment), and the optical anisotropy in the in-plane direction disappears.

  In this manner, the optical anisotropy can be changed by switching between vertical alignment and horizontal alignment in the driving liquid crystal included in the liquid crystal layer 14 under the non-application of voltage and control of application. Such a polymer dispersion type liquid crystal element 1 can be used as a constituent material of a light control material, and can be used by being attached to, for example, a window glass of a building, a showcase, an indoor transparent partition, or the like. When used as a constituent material of the light control material, the molecular dispersion type liquid crystal element 1 according to the present embodiment is a reverse mode type, and thus becomes transparent during a power failure (that is, when no voltage is applied). In addition, the power consumption can be kept low since the normality (when no voltage is applied) is transparent.

(Liquid crystal material)
The liquid crystal material constituting the liquid crystal layer 14 is not particularly limited as long as the dielectric anisotropy is negative. For example, the liquid crystal material is a polymerizable liquid crystal composition, and the polymerizable liquid crystal composition contains a liquid crystal compound (rod-like compound) that exhibits liquid crystallinity and has a polymerizable functional group in the molecule. In the present embodiment, the alignment films 13A and 13B described above function as vertical alignment films, and a homeotropic liquid crystal material is used for homeotropic alignment of the driving liquid crystal (liquid crystal compound) included in the liquid crystal layer.

  Specifically, the liquid crystal material includes a liquid crystal compound having a refractive index anisotropy and a function of imparting a desired retardation by regularly arranging the liquid crystal material. Examples of the liquid crystal compound include materials exhibiting a liquid crystal phase such as a nematic phase and a smectic phase, but the nematic phase is easier in order to arrange regularly than liquid crystal compounds exhibiting other liquid crystal phases. It is preferable to use a material exhibiting the above liquid crystallinity. The liquid crystal compound exhibiting a nematic phase is preferably a material having spacers at both ends of the mesogen.

  The liquid crystal compound is a polymerizable liquid crystal compound having a polymerizable functional group in the molecule as described above. By having a polymerizable functional group, it is possible to polymerize and fix the liquid crystal compound, so that the alignment stability is excellent and the phase change is less likely to occur over time. The polymerizable liquid crystal compound more preferably has a polymerizable functional group capable of three-dimensional crosslinking in the molecule. By having a polymerizable functional group capable of three-dimensional crosslinking, the sequence stability can be further enhanced. Note that “three-dimensional crosslinking” means that liquid crystal molecules are polymerized three-dimensionally to form a network structure.

  Examples of the polymerizable functional group include those that polymerize by the action of ionizing radiation such as ultraviolet rays and electron beams, or heat. Examples of these polymerizable functional groups include radical polymerizable functional groups and cationic polymerizable functional groups. Representative examples of radically polymerizable functional groups include functional groups having at least one addition-polymerizable ethylenically unsaturated double bond, such as vinyl groups having or without substituents, acrylate groups (acryloyl). Group, methacryloyl group, acryloyloxy group, generic name including methacryloyloxy group) and the like. Moreover, an epoxy group etc. are mentioned as a specific example of a cationically polymerizable functional group. In addition, examples of the polymerizable functional group include an isocyanate group and an unsaturated triple bond. Among them, a functional group having an ethylenically unsaturated double bond is preferably used from the viewpoint of the process.

The amount of the polymerizable liquid crystal compound is not particularly limited as long as the viscosity of the liquid crystal material can be adjusted to a desired value according to the coating method applied on the alignment film 13, but for example, the amount in the liquid crystal material is 5 mass. Part to about 40 parts by mass. In addition, a polymeric liquid crystal compound can be used individually by 1 type or in mixture of 2 or more types.
(solvent)
The liquid crystal mixture described above is usually dissolved in a solvent (dilution solvent). The solvent is not particularly limited as long as it can uniformly disperse liquid crystal compounds and the like. For example, hydrocarbon solvents such as benzene and hexane, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone (CHN). Solvent, ether solvents such as tetrahydrofuran, 1,2-dimethoxyethane, propylene glycol monoethyl ether (PGME), halogenated alkyl solvents such as chloroform and dichloromethane, methyl acetate, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate Ester solvents such as (PGMEA), amide solvents such as N, N-dimethylformamide, sulfoxide solvents such as dimethyl sulfoxide, anone solvents such as cyclohexane, methanol, ethanol, isopropyl It can be exemplified an alcohol solvent such as alcohol, but is not limited thereto. Moreover, one type of solvent may be single and 2 or more types of mixed solvents may be sufficient as it. In addition, as a quantity of a solvent, it can be set as about 66 mass parts-950 mass parts with respect to 100 mass parts of liquid crystal compounds, for example.

≪2. Manufacturing method of polymer dispersed liquid crystal element >>
Next, a method for manufacturing the polymer dispersed liquid crystal element according to the present embodiment will be described. FIG. 2 is a flowchart showing the flow of the manufacturing process of the polymer dispersed liquid crystal element. FIG. 3 is a schematic view schematically showing the flow of manufacturing the liquid crystal element.

  In the method for manufacturing a polymer-dispersed liquid crystal element according to the present embodiment, as step S1, a transparent electrode 12A made of a metal oxide film such as ITO is formed on a base film 11A, and a transparent electrode film 20A is formed. (Transparent electrode film production process).

Next, as step S2, an alignment film forming coating solution for forming an alignment film 13A made of an ultraviolet curable liquid crystal material exhibiting homeotropic alignment is applied onto the transparent electrode film 20A. After coating the coating solution, a drying treatment is performed at a predetermined temperature, and then the solution is cooled at room temperature. Thereby, the liquid crystal compound is homeotropically aligned. Furthermore, using an ultraviolet irradiation device, for example, the film is cured by irradiation with ultraviolet rays at an irradiation amount of 100 mJ / cm ² to form the alignment film 13A (alignment film forming step).

  The coating method of the alignment film forming coating solution on the base film is not particularly limited, and examples thereof include a die coating method, a gravure coating method, a reverse coating method, a knife coating method, a dip coating method, and a spray. A coating method, an air knife coating method, a spin coating method, a roll coating method, a printing method, a dip-up method, a curtain coating method, a casting method, a bar coating method, an extrusion coating method, an E-type coating method, and the like can be used.

  Next, as step S <b> 3, a liquid crystal material is applied on the formed alignment film 13 to form the liquid crystal layer 14. Specifically, a coating liquid (liquid crystal layer forming coating liquid) containing a liquid crystal material is applied onto the alignment film 13A. Thereby, the coating film for liquid crystal layers is formed (the coating-film formation process for liquid crystal layers). In addition, it does not specifically limit about the coating method of the coating liquid for liquid crystal layer formation, It can carry out by the die-coating method etc. similarly to the time of formation of alignment film.

  Next, as step S4, after forming the alignment film 13A and the coating film 14 ′ for forming the liquid crystal layer on the base film 11A, the transparent electrode film 20B (base film) in which the alignment film 13B is formed in the same manner. The transparent film 12B is formed on the material film 11B), and the liquid crystal layer forming coating film 14 'is sandwiched between the alignment films 13A and 13B (bonding step).

Next, as step S5, the film obtained by laminating the two films is irradiated with ultraviolet rays at a dose of, for example, 0.4 mW / cm ² to cure the coating film 14 ′ for forming the liquid crystal layer. Then, the liquid crystal layer 14 is formed, and the two bonded films are bonded together (ultraviolet irradiation process). Prior to the ultraviolet irradiation process, a leveling process for making the thickness of the liquid crystal layer 14 uniform may be performed.

  Through these steps, a polymer-dispersed liquid crystal element is manufactured. In addition, as a polymer dispersion type liquid crystal element, it cuts out to the desired magnitude | size and the electrode for applying a voltage to the edge part etc. is processed.

≪3. Application of VA mode to vertical alignment film >>
The alignment film for liquid crystal according to the present embodiment can be used as, for example, an alignment film of a VA mode liquid crystal display device. Conventionally, a polyimide for vertical alignment is generally used as a material for the alignment film in the VA mode. However, even in this case, when a polyimide film is used, a heat treatment at a high temperature is required, and it is limited to applicable base films.

  On the other hand, the alignment film for liquid crystal described above, that is, the alignment film for liquid crystal composed of a UV-curable liquid crystal material having a polymerizable functional group and having homeotropic alignment is used as the alignment film for VA mode. By using it, the liquid crystal compound constituting the liquid crystal layer can be appropriately homeotropically aligned, and it is not necessary to perform a high temperature treatment as in the case of using a polyimide film, and a general base film is used. Can be configured.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples of the present invention. However, the present invention is not limited to the following examples.

≪Preparation of reverse mode polymer dispersed liquid crystal element≫
[Example 1]
<Preparation of alignment film>
Using liquid crystal materials represented by the following formulas (A) and (B), 80% by mass of a side chain polymer represented by the following formula (A) and 20% by mass of polymerizable liquid crystal represented by the following formula (B) And a photopolymerization initiator (manufactured by Ciba Specialty Chemicals Co., Ltd., Irgacure 907) at a ratio of 5% by mass with respect to the liquid crystal mixture, and dissolved in a toluene solution to a solid content of 5% by mass, A leveling agent was added to prepare an alignment film composition liquid.

The prepared alignment film composition liquid was applied on the ITO side of a 100 μm-thick PET film substrate on which ITO with a sheet resistance of 150Ω / □ was formed, and then dried at 50 ° C. for 1 minute, and left as it was. The liquid crystal mixture was homeotropically aligned by cooling to room temperature. Furthermore, the curing treatment was performed by irradiating with ultraviolet rays at 100 mJ / cm ² . The film thickness after curing was about 100 nm.

  After curing, drying was performed at 120 ° C. for 2 minutes in order to evaporate the solvent remaining in the film.

<Preparation of mixed liquid crystal material>
Next, with respect to 80 parts by mass of nematic liquid crystal (Δε = −4.5, Δn = 0.18) having a negative dielectric anisotropy, 19 parts by mass of isobornyl acrylate, a photopolymerization initiator (Ciba Specialty Chemicals) A mixed liquid crystal material for a reverse mode was prepared by mixing 1 part by mass of Irgacure 651).

<Production of Reverse Mode Polymer Dispersed Liquid Crystal Device>
Prepare two PET film base materials (100 μm thick base material on which ITO with a sheet resistance of 150Ω / □) is formed as described above, and apply spacer dry on one base material. A spacer agent (Sekisui Chemical Co., Ltd., Micropearl SP206) having a diameter of 6 μm was sprayed using a device (manufactured by NG Co., Ltd., SDI-12), and the prepared mixed liquid crystal material was coated on the other substrate. Was applied.

Then, two substrates were bonded and irradiated with 0.4 mW / cm ² ultraviolet rays for 10 minutes to produce a reverse mode polymer dispersion type liquid crystal element.

[Example 2]
<Preparation of alignment film>
An alignment film composition was prepared by mixing 66.5 parts by mass of isobornyl acrylate and 3.5 parts by mass of a photopolymerization initiator with respect to 30 parts by mass of the alignment film material used in Example 1. Then, in the same manner as in Example 1, the prepared alignment film composition liquid was applied to the transparent electrode side of the transparent substrate with a bar coater, dried at 120 ° C. for 2 minutes, cooled to room temperature as it was, and further 100 mJ It was cured by irradiating with UV light of / cm ² . The film thickness after curing was about 100 nm.

<Production of Reverse Mode Polymer Dispersed Liquid Crystal Device>
Using the same mixed liquid crystal material as that prepared in Example 1 using the PET film substrate coated with the alignment film as described above, a reverse mode polymer dispersion type liquid crystal device was prepared in the same manner. did.

[Reference example (reference example using a vertical alignment film made of polyimide)]
<Preparation of alignment film>
An alignment film composition solution was prepared by diluting a solution of a vertical alignment film made of a polyimide resin (JAL Co., Ltd., JALS-2021-R2) twice with γ-butyrolactone.

  Next, an ITO film having a sheet resistance of 150Ω / □ is formed on the surface of a glass substrate (Corning, 7059 glass), and the prepared alignment film composition liquid is applied to prepare a coating film for forming an alignment film. Two substrates (hereinafter referred to as “vertical alignment film forming substrate”) on which a vertical alignment film was formed by baking a glass substrate on which an alignment film forming coating film was formed at 180 ° C. for 1 hour. Produced.

  Then, on one base material, a spacer agent having a diameter of 6 μm (manufactured by Sekisui Chemical Co., Ltd., Micropearl SP206) is sprayed using a spacer dry spraying device (manufactured by ING Corporation, SDI-12), and an edge A sealing material (manufactured by Mitsui Chemicals, XN-5A) was applied to the alignment film) using a seal dispenser device. Thereafter, the other substrate was bonded to the alignment film so that the alignment film was on the inside, and a pressure of about 20 kPa was applied using a press jig to bring the two liquid crystal alignment substrates into close contact with each other. In this state, heat treatment was performed under the conditions of a temperature of 180 ° C., a time of 60 minutes, and a cooling standing time of about 30 minutes, and an empty cell having a gap of about 10 μm was produced.

Into this empty cell, a mixed liquid crystal material similar to that produced in Example 1 was injected using a vacuum injection device, and after sealing the injection port, 0.4 mW / cm ² ultraviolet rays were irradiated for 10 minutes. Then, a reverse mode polymer dispersed liquid crystal element was produced.

≪Characteristic evaluation≫
A voltage was applied from 0 V to 100 V with respect to the reverse mode polymer dispersion type liquid crystal elements produced in Example 1, Example 2, and Reference Example, and the relationship between the applied voltage and haze was measured. FIG. 4 shows a graph showing the measurement results.

  As is apparent from the measurement result graph of FIG. 4, by using the alignment film used in Examples 1 and 2, even when a film base material is used, a polyimide vertical alignment film is used. It was found that a reverse mode polymer dispersion type liquid crystal element having the same performance as that of (Reference Example) can be produced.

DESCRIPTION OF SYMBOLS 1 Polymer dispersion type liquid crystal element 11A, 11B Base film 12A, 12B Transparent electrode 13A, 13B Alignment film 14 Liquid crystal layer

Claims (6)

An alignment film for liquid crystal, characterized in that ultraviolet curable liquid crystal is homeotropically aligned on a transparent film substrate. The mixture comprising the homeotropic alignment type ultraviolet curable liquid crystal and the ultraviolet curable resin mixed at a ratio of 30:70 to 99: 1 is applied to the transparent film substrate. Item 2. A liquid crystal alignment film according to Item 1. An alignment film for liquid crystal, characterized in that ultraviolet curable liquid crystal is homeotropically aligned on a transparent electrode formed on a transparent film substrate. 4. The mixture of the homeotropic alignment type ultraviolet curable liquid crystal and the ultraviolet curable resin in a ratio of 30:70 to 99: 1 is applied on the transparent electrode. 2. An alignment film for liquid crystal according to 1.   A reverse mode polymer dispersion type liquid crystal device using the alignment film for liquid crystal according to claim 3. A VA mode liquid crystal element using the alignment film for liquid crystal according to claim 3.