JPH05127151A - Light control material and light control element formed by using the same - Google Patents

Abstract

PURPOSE:To improve voltage sensitivity and to decrease voltage by incorporating a high polymer obtd. by copolymerizing a photopolymerizable compsn. contg. acrylonitrile and acrylic acid deriv. and/or methacrylic acid deriv. into the material. CONSTITUTION:The high-polymer material of the light control material which contains a liquid crystal and high polymer and controls the transmission and scattering of light according to the presence and absence of electric field impression is obtd. by copolymerizing the photopolymerizable compsn. contg. acrylonitrile and the (meth)acrylic acid deriv. The (meth)acrylic acid deriv. is exemplified by (meth)acrylate, etc., and more preferably, the (meth)acrylate having 1 to 6 pieces of (meth)acrylate groups in one molecule is usable. On the other hand, a mixture composed of one or 2 kinds selected from a group consisting of a nematic liquid crystal, smectic liquid crystal and cholesteric liquid crystal is usable as the liquid crystal. The inert mixture is selected for this high polymer and the light control element is formed by lamping this light control material between a pair of substrates with electrodes, at least one of which are transparent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light control material and a light control element including the same.

[0002]

2. Description of the Related Art A dimming material composed of liquid crystal and a polymer holding the liquid crystal has a liquid crystal layer formed by scattering the incident light due to a difference between the refractive index of the polymer and that of the liquid crystal when no electric field is applied. On the other hand, when the electric field is applied, the liquid crystal aligns in the direction of the electric field, so that the refractive index of the polymer and the refractive index of the liquid crystal are close to each other, resulting in the transparent state. When the electric field is removed, the original cloudy state is restored.

Conventionally, a light control element utilizing such a property is disclosed in, for example, Japanese Patent Laid-Open No. 64-62615, Japanese Patent Publication No.
No. 502929 and Japanese Patent Laid-Open No. 1-312527.

[0004]

The light control element is required to have arbitrary transmittance, repetitive response, voltage sensitivity, response speed, film uniformity, light resistance, heat resistance, water resistance, etc. However, none of the above-mentioned conventional techniques can satisfy these required characteristics. The present invention solves the above problems, and solves the characteristics required for a light control element, particularly the voltage sensitivity, and enables the voltage to be reduced.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a dimming material containing a liquid crystal and a polymer, which controls transmission / scattering of light depending on whether or not an electric field is applied, wherein the polymer is acrylonitrile and an acrylic acid derivative. And / or a polymer obtained by copolymerizing a photopolymerizable composition containing a methacrylic acid derivative, and at least one of the light control materials is transparent,
The gist of the invention is a light control element sandwiched between a pair of substrates having electrodes on the inner surface.

The present invention will be described in detail below. The polymer contained in the light control material of the present invention is obtained by copolymerizing a photopolymerizable composition containing acrylonitrile and a (meth) acrylic acid derivative. Examples of the (meth) acrylic acid derivative include (meth) acrylic acid ester and (meth) acrylic acid amide, and preferably (meth) acrylic acid ester. As the (meth) acrylic acid ester preferably used in the photopolymerizable composition of the present invention,
Any (meth) acrylic acid ester group may be used as long as it has a (meth) acrylic acid ester group.
Those having 1 to 6 in the molecule can be used. These (meth) acrylic acid esters are preferably used as a mixture of two or more kinds. In particular, when a compound having one (meth) acrylic acid ester group is used, by itself,
Since it may be difficult to form a film by photopolymerization, it is preferable to use a mixture with a compound having two or more (meth) acrylic acid ester groups.

Among the (meth) acrylic acid esters used in the present invention, monofunctional (meth) acrylic acid esters include aliphatic linear or branched alcohols, cyclohexanol, tetrahydrofurfuryl alcohol, ethylene glycol monoalkyl ethers, (Meth) acryl of polyethylene glycol, monoalkyl ether, propylene glycol, monoalkyl ether, polypropylene glycol, monoalkyl ether, 1,3-butylene glycol monoalkyl ether, tetramethylene glycol monoalkyl ether or hexamethylene glycol, monoalkyl ether Examples thereof include acid esters.

As the polyfunctional (meth) acrylic acid ester, ethylene glycol, polyethylene glycol,
Propylene glycol, polypropylene glycol,
Poly (meth) acrylic acid esters of diols such as 1,3-butylene glycol, tetramethylene glycol and hexamethylene glycol and polyols such as trimethylolpropane, glycerin and tetramethylolmethane, trimethylolpropane and tetramethylolmethane Alternatively, poly (meth) acrylic acid esters of a polyol obtained by adding ethylene oxide or propylene oxide to isocyanuric acid can be mentioned.

When the polyfunctional (meth) acrylic acid ester and the monofunctional (meth) acrylic acid ester are used in combination, the ratio of use is as follows: polyfunctional (meth) acrylic acid ester / monofunctional (meth) acrylic acid ester = 10/1 to 1/10
It is selected from the range of (weight ratio). Examples of the (meth) acrylic acid amide include acrylamide and methacrylamide, and the nitrogen atom of the amide group may be substituted with an alkyl group or an alkoxyalkyl group. Specifically, N- (n-butoxymethyl) -acrylamide is used. Can be mentioned. The amount of acrylonitrile used in the photopolymerizable composition containing acrylonitrile is preferably 1 to 50% by weight, and particularly 5
-30% by weight is preferred.

On the other hand, as the liquid crystal, one kind or a mixture of two or more kinds selected from the group consisting of nematic liquid crystal, smectic liquid crystal and cholesteric liquid crystal can be used, as long as it is inert to the reaction of the polymer. There is no particular limitation. Of these, nematic liquid crystal is particularly preferably used.

The nematic liquid crystal used in the present invention includes:
A wide range can be selected as long as it exhibits a nematic state in the operating temperature range. Moreover, a cholesteric state can be obtained by adding an optical rotatory substance described later to such nematic liquid crystal. Examples of the nematic liquid crystal include the substances shown in Table 1 below and derivatives thereof.

[0012]

[Table 1] Table-1

[0013]

[Table 2] Table-1 (continued)

[0014]

[Table 3] Table-1 (continued)

In Table 1 above, R'is an alkyl group or an alkoxy group, R is an alkyl group, and X'is an alkyl group, an alkoxy group, a nitro group, a cyano group, a trifluoromethyl group, a trifluoromethoxy group or a halogen. Represents an atom. Further, the benzene ring in Table 1 above may be further substituted with a fluorine atom.

The liquid crystal used in the present invention may be any of the liquid crystals shown in Table 1 or a mixture containing them.
For example, ZLI-1132, ZLI-184 from Merck
0 or liquid crystal sold under the trade name ZLI-1565, or sold by British drug house under the trade names E-7, E-8, E-37, E-44, E-46 or BL001-BL020. Liquid crystal is used. Moreover, a cholesteric state can be obtained by adding the following optical rotatory substances to such nematic liquid crystal.

The optically active substance used in the liquid crystal composition of the present invention is a chiral nematic compound, for example, 2-methylbutyl group, 3-methylbutoxy group, 3-methylpentyl group, 3-methylpentoxy group, 4-methyl group. There is a compound in which an optically active group such as a hexyl group and a 4-methylhexoxy group is introduced into a nematic liquid crystal. In addition, JP-A-51-
No. 45546, alcohol derivatives such as 1-menthol and d-borneol, d-camphor, ketone derivatives such as 3-methylcyclohexane, d-citronellic acid, 1
A carboxylic acid derivative such as camphoric acid, an aldehyde derivative such as d-citronellal, an alkene derivative such as d-linonene, and other optically active substances such as amine, amide and nitrile derivatives can be used.

The smectic liquid crystals used in the present invention include smectic A liquid crystals and smectic chiral C liquid crystals.
A liquid crystal is mentioned. Next, as the method of manufacturing the light control material,
The liquid crystal, the photopolymerizable composition containing the acrylonitrile, and the photopolymerization initiator are mixed and optionally heated to form a uniform solution and exposed. As a result, the copolymer and the liquid crystal are in a phase separated state, and a light control material can be obtained.

At this time, the ratio of liquid crystal in the homogeneous solution is
40 to 90% by weight, preferably 65 to 85% by weight
Is. As the photopolymerization initiator, 2,2-dimethoxy-
2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one and the like can be mentioned.

If necessary, a surfactant, a light stabilizer, a dichroic or non-dichroic dye, a chain transfer agent, a photosensitizer, a cross-linking agent and the like can be used in combination. On the other hand, a transparent electrode such as ITO is used as the electrode of the light control device of the present invention, and a transparent substrate such as a glass or plastic plate such as polyester is used as the electrode substrate.

When a pair of transparent electrode substrates is used, it can be used as a transmissive dimming element, and when one electrode substrate is transparent and the other is opaque, the opaque electrode substrate is followed by reflectivity. By placing a layer, it can be used as a reflection type light control device. The light control element of the present invention is, for example, exposed as a uniform solution containing the above-mentioned liquid crystal, polymerizable composition and photopolymerizable initiator and, if necessary, various additives, sandwiched between the substrates having the above electrodes. It can be produced by polymerizing the polymerizable composition.

[0022]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to the following examples.

[0023]

[Example 1] 0.05 g of trimethylolpropane triacrylate, 0.085 g of n-butyl acrylate, 0.015 g of acrylonitrile, and 2,2 as a polymerization initiator
-Dimethoxy-2-phenylacetophenone 0.003
g, and 0.35 g of E-8 (manufactured by BDH) as a liquid crystal were mixed to obtain a uniform solution, and 0.008 g of a plastic (divinylbenzene copolymer) spacer having a diameter of 10 μm was added to the solution. This mixed solution was inserted into a 6 cm × 9 cm size plastic with ITO (polyethylene terephthalate having a thickness of 125 μm), and exposed by an ultraviolet irradiation device to obtain a uniform light control element without cracks. The applied energy corresponds to 800 mJ. When an alternating current (60 Hz, sine wave) of 100 V was applied to the obtained light control element, the transmittance reached a constant value,
It was 81% when viewed at a wavelength of 00 nm. Also, 100
An applied voltage of 49 V was necessary to obtain a transmittance (73%) of 90% of the transmittance when V was applied.

Comparative Example 1 Instead of using 0.085 g of n-butyl acrylate and 0.015 g of acrylonitrile of Example 1, 0.1 g of n-butyl acrylate was used, and the same treatment as in Example 1 was carried out. A uniform light control element without cracks or the like was obtained.
When 100 v AC (60 Hz, sine wave) was applied to the obtained light control device, the transmittance reached a constant value. 600
The wavelength was 80% when viewed at a wavelength of nm, and an applied voltage of 60 V was required to obtain this 90% transmittance (72%), which was inferior to that of Example 1.

Example 2 0.05 g of tris-acryloxyethyl isocyanurate was used in place of 0.05 g of trimethylolpropane triacrylate of Example 1, and the other treatments were performed in the same manner to obtain uniform dimming without cracks. A device was obtained. When an alternating current of 100 V (60 Hz, sine wave) was applied to the obtained light control device, the transmittance reached a constant value, and it was 79% when viewed at a wavelength of 600 nm. In addition, the transmittance of 9 when applying 100 V
An applied voltage of 23 V was necessary to obtain 0% transmittance (71%).

Comparative Example 2 Instead of using 0.085 g of n-butyl acrylate and 0.015 g of acrylonitrile of Example 2, 0.1 g of n-butyl acrylate was used, and the same procedure as in Example 2 was repeated. A uniform light control element without cracks or the like was obtained.
When an alternating current of 100 V (60 Hz, sine wave) was applied to the obtained light control element, the transmittance reached a constant value and 600 nm.
When viewed at the wavelength of 80%, it shows 80%, and this transmittance of 90% (7
2%) requires an applied voltage of 40V,
It was inferior to Example 2.

Example 3 As a photopolymerizable composition, 0.05 g of trimethylolpropane triacrylate, 0.05 g of methoxynonaethylene glycol methacrylate, 0.03 of acrylonitrile.
Using the composition of g, and otherwise treating in the same manner as in Example 1, a uniform light control device without cracks or the like was obtained. When 100 V (60 Hz, sine wave) alternating current was applied to the obtained light control element, the transmittance reached a constant value and showed 80% when viewed at a wavelength of 600 nm. This transmittance of 90% (72%) It was necessary to apply an applied voltage of 45 V in order to obtain

COMPARATIVE EXAMPLE 3 In place of 0.03 g of acrylonitrile of Example 3, 0.03 g of methoxynonaethylene glycol methacrylate was further added, and otherwise the same treatment as in Example 3 was carried out to obtain a uniform preparation without cracks. An optical device was obtained. When an alternating current of 100 V (60 Hz, sine wave) was applied to the obtained light control element,
The transmittance reaches a certain value and is 8 when viewed at a wavelength of 600 nm.
The applied voltage of 59 V was required to obtain the transmittance of 90% (72%), which was inferior to that of Example 3.

[0029]

The light control material obtained by the present invention has good film uniformity, and the light control element using the light control material has excellent voltage sensitivity and is useful for display devices, light control windows and the like. ..

Claims (2)

[Claims] 1. A light control material containing a liquid crystal and a polymer, which controls transmission / scattering of light depending on whether or not an electric field is applied, wherein the polymer contains acrylonitrile and an acrylic acid derivative and / or a methacrylic acid derivative. A light control material, which is a polymer obtained by copolymerizing a polymerizable composition. 2. A dimming device comprising a dimming material according to claim 1 sandwiched between a pair of substrates having electrodes on the inner surface, at least one of which is transparent.