JPH046526A - Light control element - Google Patents

Abstract

PURPOSE:To provide high light resistance and chemical stability (weatherability) and to prolong a life by forming a transparent medium of transparent inorg. matter. CONSTITUTION:This light control element is constituted by inserting a liquid crystal layer 1 formed by dispersing a liquid crystal 10 into the transparent medium 11 between a pair of electrodes 2a and 2b which face each other and at least either of which is transparent. The transparent medium 11 of such light control element is the transparent inorg. matter. The transparent inorg. medium is not particularly limited, insofar as the medium is the transparent inorg. matter having high light resistance and chemical stability and is preferably the inorg. matter formed by bringing, for example, metal alkoxide into sol-gel reaction, etc. If the transparent inorg. matter is used as the transparent medium in such a manner, the light resistance and chemical stability (weatherability) of the light control element are enhanced and the life of the light control element is improved as the inorg. matter has generally the high light resistance and chemical stability.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention can change the light transmittance by applying a voltage, and can be applied to windows, partitions, display windows, etc. of houses and offices, The present invention relates to a light control element used for display purposes such as signs.

[Conventional technology]

Conventionally, several patent applications have been filed for light control elements that have a structure in which a liquid crystal layer made of nematic liquid crystal dispersed in a transparent polymer medium is inserted between a pair of opposing transparent electrodes. There is. For example, as a transparent polymer medium for dispersing liquid crystals, polyvinyl alcohol is used (see Japanese Patent Publication No. 58-501631, etc.), latex is used (see Japanese Patent Application Laid-open No. 60-252687, etc.), and epoxy resin is used. Those using
02128, etc.), and those using an acrylic photocurable resin (see JP-A-1-229232, etc.).

[Problem to be solved by the invention]

However, in the above-mentioned light control elements, organic polymers that are sensitive to light, especially ultraviolet rays, and have low chemical stability are used as the transparent polymer medium in which the liquid crystal is dispersed. There was a problem that it deteriorated easily and had a short lifespan.

In view of these circumstances, an object of the present invention is to provide a light control element that has high light resistance and chemical stability (weather resistance) and has a long life.

[Means for Solving the Problems 2] In order to solve the above-mentioned problems, a light control element according to the present invention is formed by dispersing liquid crystal in a transparent medium between a pair of opposing electrodes, at least one of which is transparent. A light control element having a structure in which a liquid crystal layer is inserted is characterized in that the transparent medium is a transparent inorganic substance.

The transparent inorganic medium used in this invention is not particularly limited as long as it is a transparent inorganic material with high light resistance and chemical stability, but it is preferably formed by a sol-gel reaction of a metal alkoxide, for example. .

The metal alkoxide is not particularly limited, and includes, for example, Si, AI! ,B,Ce,Ge,In%L
a 1N b −, S b , S n % T a ,
Methoxide, ethoxide, propoxide, etc. of Tt, ■, W, Zr, etc. can be used alone or in combination, but it is preferable that at least the main component is silicon alkoxide.

The silicon alkoxide is not particularly limited, but it is preferable to use one represented by the following general formula (1). In that case, although not particularly limited, it is more preferable to use a mixture of silicon alkoxides having a plurality of n values than to use silicon alkoxides having a single n value in the above formula (■). In the formula (1), specific examples of R include alkyl groups such as methyl group, ethyl group, butyl group, cyclohexyl group, phenyl group, vinyl group, chloromethyl group, γ-methacryloxypropyl group, glycidoxy Examples include, but are not limited to, propyl groups. Note that the metal alkoxide may have a hydrolyzable group other than an alkoxide group, such as an acetoxy group, an oxime group, an enoxy group, an amino group, an amide group, and the like.

The sol-gel reaction for forming the transparent inorganic medium from the metal alkoxide is not particularly limited, but preferably involves a hydrolysis reaction and a condensation reaction. Specifically, in the case where silicon alkoxide is used as the metal alkoxide, the following may be mentioned.

5i-OR+ H*O→ 5i-OH+ ROH...
When forming the hydrolysis reaction transparent inorganic medium, if necessary, ultrafine powder such as colloidal silica, zinc oxide (ZnO), titanium oxide (TiOz) with a particle size of 0.005 to 0.4μ, Alternatively, fine silica powder or the like having a slightly larger size than these may be added in an amount that does not impede the transparency of the transparent inorganic medium to be formed. This is because these materials have ultraviolet absorbing ability, so that the light resistance of the transparent inorganic medium to be formed is further improved. Further, if necessary, a thickener, a colorant, an antifoaming agent, a surface smoothing agent, etc. may be added. In addition, in the case of a light control element using a coloring agent that changes color when a voltage is applied, not only the light transmittance but also the color tone changes by applying the voltage. The liquid crystal to be used is not particularly limited, but includes, for example, nematic liquid crystal, smectic liquid crystal, etc. whose molecules are oriented under an electric field. These can be used alone or in combination.

Such liquid crystals may be continuously dispersed in the transparent inorganic medium, or may be encapsulated in microcapsules whose shell walls are made of organic resin, so to speak, in an aggregated state (hereinafter referred to as "liquid crystal cell"). '') may be distributed independently from each other. Moreover, these two dispersion modes may be used together.

The particle size of the liquid crystal cell is not particularly limited, but in order to cause light scattering (diffusion) when no voltage is applied, it must be 0.
It is preferable that it is 1 trm or more.

Of course, the refractive index of the liquid crystal and the transparent inorganic medium must be such that a light control element having desired performance can be obtained. In other words, when no voltage is applied, liquid crystal molecules are randomly oriented, but due to such random orientation, light rays entering the liquid crystal layer cannot travel straight and are scattered, resulting in the dimming of the light control element. Must be opaque. In order for such a light scattering phenomenon to occur, it is necessary that the average refractive index of the liquid crystal when no voltage is applied is different from the refractive index of the transparent inorganic medium. on the other hand,
When a voltage is applied, the liquid crystal molecules are aligned parallel to the direction of the electric field, but in order for the dimming element to be transparent when the same voltage is applied, the refractive index of the liquid crystal with respect to the incident light must be transparent. The refractive index must almost match that of the inorganic medium to eliminate light scattering and reflection. In addition, in the case of a light control element in which liquid crystal is dispersed as a liquid crystal cell in a transparent inorganic medium, the same conditions as for the transparent inorganic medium are satisfied between the refractive index of the wall material of the liquid crystal cell and the refractive index of the liquid crystal. It becomes necessary.

The thickness of the liquid crystal layer formed by dispersing the liquid crystal in the transparent inorganic medium is not particularly limited, but is preferably about 5 to 50 nm in order to obtain desired performance.

The content of the transparent inorganic medium and liquid crystal in the liquid crystal layer is not particularly limited, but it is usually preferable that the content of the liquid crystal is 10 to 90% by weight based on the solid content of the transparent inorganic medium.

If the liquid crystal content is 10% by weight without grooves, sufficient light scattering properties cannot be obtained when no voltage is applied, while if it exceeds 90% by weight, the amount of transparent inorganic medium is insufficient, and the desired This is because it may become impossible to form a liquid crystal layer.

The electrode used in this invention is not particularly limited, but for example, silicon dioxide (S
Examples include those formed with a conductive film made of noble metals such as iO, indium oxide (InzOs), tin and indium oxide (ITO), and palladium. The base material is not particularly limited, but glass, plastic film, etc. are preferable. Specifically, in the case of glass,
Soda glass, borosilicate glass, etc. may be used, while plastic films include polyethylene terephthalate, acrylic, and the like.

The resistance value required for the electrode is not particularly limited, as long as it acts as an electrode, and usually θ
It is sufficient if it is in the range of ~ several hundred Ω.

In addition, in this invention, it is sufficient that the electrode on at least one side of the light control element is transparent. That is, the electrode on one side may be transparent and the electrode on the other side may be an opaque material such as a metal such as aluminum, gold, silver, copper, or the like. In the case of such a light control element, it acts not on transmitted light but on reflected light.

[For production]

If a transparent inorganic substance is used as the transparent medium, since inorganic substances generally have high light resistance and chemical stability, the light resistance and chemical stability (weather resistance) of the light control element will be increased, and the life of the light control element will be increased. improves.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described in detail based on the drawings, but the invention is not limited to the following embodiments.

FIG. 1 shows an embodiment of a light control element according to the present invention. As shown in the figure, this light control element has a structure in which a liquid crystal layer 1 consisting of liquid crystal cells 10 dispersed in a transparent inorganic medium 11 is inserted between a pair of opposing transparent electrodes 2a and 2b. It is light-opaque when no voltage is applied between the transparent electrodes 2a and 2b, but becomes light-transparent when a voltage is applied.

Although the method for manufacturing such a light control element is not particularly limited, it may be performed, for example, as follows.

First, the liquid crystal cell 10 is prepared, and this can be done by a known method using the liquid crystal ["Synthetic Polymer Microcapsules" Toshiaki Masuda, Polymer Processing 3rd Edition]
8, No. 6, pp. 293-298 (1989)], the wall material of the liquid crystal cell 10 needs to have transparency, solvent resistance, etc., so the membrane material polymerization method is selected. Ru.

For example, In-5 using melamine-formalin resin
In-5 using itu condensation polymerization method, acrylic thread picker
Itu radial polymerization method etc. are carried out.

The obtained liquid crystal cell 10 is dispersed in the following inorganic coating liquid. The inorganic coating liquid is composed of the metal alkoxide, the inorganic fine powder, water as a reaction agent, a solvent, etc., in order to form a weather-resistant and scratch-resistant coating. For example, a coating composition consisting of an organoalkoxysilane, a partial hydrolyzate of the same silane, and colloidal silica (JP-A-51-0736, JP-A-5
3-130732), a coating composition prepared by adding water as a curing agent and a catalyst to a partial condensate of alkoxysilane immediately before use (see JP-A-64-168, etc.), etc. . The solvent includes alcohol,
Ester and benzene-based solvents may be used alone or in combination.

After coating the transparent electrode 2a with the inorganic coating liquid in which the liquid crystal cells 10 are dispersed, the solvent is evaporated at room temperature or by heating. If necessary, heating is continued to complete the curing reaction to obtain a semi-finished product A as shown in FIG.

Apply a thin layer of adhesive or pressure-sensitive adhesive to the surface of the semi-finished product A where the transparent electrode 2a is not attached, or join the other transparent electrode 2b, or
Alternatively, two semi-finished products A are produced and bonded to each other via a thin adhesive layer or pressure-sensitive adhesive layer so that the transparent electrode is on the outside to obtain a light control element.

In addition, when dispersing the liquid crystal continuously in the inorganic transparent medium instead of as liquid crystal cells, after dissolving and dispersing the liquid crystal in the inorganic coating liquid, coat it on the electrode in the same manner as above. Just do it.

More specific embodiments of this invention will be described below.

In addition, in the following examples, "parts" represent "parts by weight".

Example 1 - In-
A liquid crystal cell was prepared by a 3-itu condensation polymerization method. The particle size of the liquid crystal cell was 5 to 10 μm, and the encapsulation rate was about 70%.

100 parts of methyltrimethoxysilane, 75 parts of tetraethoxysilane, IPA organosol (O5CAL 14
32. 72 parts of SiOx (30% by weight), 30 parts of dimethyljethoxysilane and 100 parts of isobutyl alcohol (IPA), and further 0. I N H
10 parts of Cl and 70 parts of water were added and stirred to prepare an inorganic coating material.

20 parts of the liquid crystal cell was added to 100 parts of the inorganic coating material (solid content: 20 parts), uniformly dispersed, and then cast onto a Nesa glass plate. After air drying and volatilizing the solvent, 1
A semi-finished product A was obtained by heating at 20° C. for 1 hour. The thickness of the liquid crystal layer in semi-finished product A was 15 μm. Such a semi-finished product A
A light control element was obtained by fabricating two sheets, applying a thin layer of transparent adhesive to the surface of the liquid crystal layer side, and stacking and bonding them together with the liquid crystal layer on the inside. The optical element was opaque, but turned transparent when voltage was applied. Further, this light control element had excellent light resistance and chemical stability (weather resistance), and had a long life.

〔Effect of the invention〕

The light control element according to the present invention has a long lifespan because a transparent inorganic substance with high light resistance and chemical stability (weather resistance) is used as a transparent medium in which liquid crystal is dispersed.

[Brief explanation of drawings]

FIG. F is a side sectional view showing one embodiment of the light control element according to the present invention, and FIG. 2 is a side sectional view showing a semi-finished product of the light control element. 1...Liquid crystal layer 10...Liquid crystal 11...Transparent inorganic medium 2a, 2b...Transparent electrode A...Semi-finished product drawing agent Patent attorney Takehiko Matsumoto Procedural assistance device (Heisei patent application) No. 02-109420, June 26, 2016, 6, Specification subject to amendment 7, Contents of amendment■ Page 9, line 15 of the specification states “Silicon dioxide (Stow
) J is corrected to read ``Snow J.''
Name (583) Matsushita Electric Works Co., Ltd. 4, Agent

Claims (1)

[Scope of Claims] 1. A light control element having a structure in which a liquid crystal layer formed by dispersing liquid crystal in a transparent medium is inserted between a pair of opposing electrodes, at least one of which is transparent, wherein the transparent medium is transparent. A light control element characterized by being an inorganic substance. 2. The light control element according to claim 1, wherein the liquid crystal is a nematic type and/or a smectic type liquid crystal. 3. The light control element according to claim 1 or 2, wherein the liquid crystal is encapsulated in microcapsules. 4. The light control device according to any one of claims 1 to 3, wherein the transparent inorganic medium is formed by subjecting a metal alkoxide to a sol-gel reaction. 5. A light control element according to any one of claims 1 to 3, wherein at least the main component of the metal alkoxide is silicon alkoxide. 4. The light control element according to 4. 6 Silicon alkoxide has the following general formula (I) R_n
Si(OR')_4_-_n...(I) [wherein, R
represents a substituted or unsubstituted monovalent hydrocarbon group, R' represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 0 to 2. However, when n is 2, R may be the same or different. ] The light control element according to claim 5, which is represented by the following. 7. The light control element according to claim 4, wherein the sol-gel reaction involves a hydrolysis reaction and a condensation reaction.