JPH05346572A - Liquid crystal film and liquid crystal constituting body - Google Patents

Abstract

PURPOSE:To facilitate construction, to enhance durability and to make driving possible at a low voltage by constituting the liquid crystal film of a resin film contg. fluorine atoms and liquid crystal drops. the associate thereof, etc. CONSTITUTION:This liquid crystal film 30 consists of the resin film contg. 1 to 10% (based on the number of atoms) fluorine atoms and the liquid crystal drops of 0.5 to 5mum diameters existing dispersedly therein and the associate thereof and/or the three-dimensional network continuous phases of the liquid crystal. This liquid crystal constituting body is constituted by disposing the resin film between a first electrode consisting of a transparent conductive layer 20 and a second electrode consisting of a conductive layer in electrical contact with the respective layers. The blank material of the resin contg. 1 to 10%, more preferably 1 to 5% (based on the number of atoms) fluorine atoms is not particularly limited, insofar as the liquid crystal phase exists stably therein and the resin does not adversely affect the liquid crystal. A more preferable example which can be most easily produced includes an acrylate resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal film and a structure using the same, and more specifically, a transparent polymer resin in which liquid crystal droplets, aggregates thereof and / or a three-dimensional network continuous phase of liquid crystal are dispersed. A liquid crystal film consisting of 2
The structure sandwiched by two electrode layers is such that the liquid crystal layer can be changed to transparent or opaque by applying a voltage to the electrodes.

[0002]

2. Description of the Related Art In a liquid crystal film in which liquid crystal molecules are microencapsulated and then dispersed in a resin film as liquid crystal droplets, the opacity due to light scattering by the liquid crystal droplets and the liquid crystal inside the liquid crystal droplets by applying an electric field Ferguson et al. (US Pat. No. 4,435,047) have already proposed a liquid crystal construct that utilizes transparency due to the orientation of molecules, and some have been put to practical use. However, this method is complicated in the production process because it includes a step of microencapsulation. Moreover, a high voltage of about 100 V is required to obtain a transparent / opaque shutter function.

On the other hand, at Kent University
-502128 and Japanese Patent Publication No. 63-501512
In the publication, it is proposed to form liquid crystal layers by dispersing liquid crystal microdroplets in a thermosetting resin translucent matrix by phase separation from a mixed solution of thermosetting resin and liquid crystal molecules. However, even the above-mentioned liquid crystal structure has a drawback that the AC voltage of about 100 V is required for orienting the liquid crystal and the power consumption is high, and when it is used not only for dimming applications but also as a display element, the driving circuit From a design standpoint, a liquid crystal structure that can be driven at a low voltage is desired.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a liquid crystal film and a liquid crystal structure thereof, which makes it possible to provide a liquid crystal structure which has a simple structure, excellent durability, and can be driven at a low voltage. Is something

[0005]

The present invention is 1-10%
A resin film containing (atomic number basis) fluorine atoms and a liquid crystal droplet having a diameter of 0.5 to 5 μm dispersed therein, a liquid crystal droplet thereof, and / or a liquid crystal film comprising a three-dimensional network continuous phase of liquid crystal. And a first electrode in which the resin film is made of a transparent conductive layer and a second electrode made of a conductive layer
Is a liquid crystal structure that is arranged between the electrodes and is in electrical contact with them.

The liquid crystal film of the present invention is a resin film containing 1 to 10%, preferably 1 to 5% (based on the number of atoms) of fluorine atoms, in which liquid crystal droplets having a diameter of 0.8 to 5 μm, It contains the aggregate and / or the three-dimensional network continuous phase of liquid crystal in a dispersed manner. The thickness of the resin film (which also becomes the thickness of the liquid crystal film after all) is not particularly limited, but is generally 50 μm or less, preferably 2 to 30 μm when considering an application requiring driving at a voltage as low as possible. is there.

Fluorine atom is 1 to 10%, preferably 1 to
The material for the resin film containing 5% (based on the number of atoms) is not particularly limited as long as the liquid crystal phase is stably present therein and the resin does not adversely affect the liquid crystal. An acrylate resin can be mentioned as a preferred example which can be most easily produced.

As a means for incorporating fluorine into the acrylate resin, it is convenient to use a fluorine-substituted one as the (meth) acrylate compound which is a raw material of the acrylate resin.

At this time, all of the raw materials may be substituted with a predetermined amount of fluorine, but an appropriate amount of fluorine-substituted (meth) acrylate compound and a (meth) acrylate compound containing no fluorine atom are mixed. Is easy to use. In the present specification, “(meth) acry…
"..." means "acry ... and / or metaacry ...". These can be monofunctional or polyfunctional monomers or their oligomers.

Among these, a cured resin made of a monofunctional monomer compound is preferably used as a resin suitable for a liquid crystal construct capable of operating at a low voltage. More preferred monomers include the following general formula (II)

[0011]

[Chemical 2] [In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n represents an integer of 1 to 14] A phenoxyoligoethylene oxide acrylate monomer (hereinafter sometimes referred to as "EOA") Can be mentioned.

As the alkyl group having 1 to 10 carbon atoms represented by R ₁ , nonyl group, methyl group, ethyl group, propyl group, butyl group, isopropyl group, isobutyl group and isopentyl group are preferably used.

More preferably, n is 1-8.

Specific examples of the EOA represented by the general formula (II) include:

[0015]

[Chemical 3] And so on. In addition to the compound represented by the general formula (II), the EOA may contain 20% by weight or less of a monofunctional or polyfunctional acrylate monomer containing no fluorine atom other than the compound.

The monofunctional monomers that can be contained in this EOA include ethyl carbitol acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-hydroxypentyl acrylate, and 2
-Hydroxy-3-phenoxypropyl acrylate,
Mention may be made of tetrahydrofurfuryl acrylate. Further, as the polyfunctional monomer, polypropylene glycol diacrylate, polyethylene glycol diacrylate, etc. are preferably used.

In the present invention, a (meth) acrylate containing a fluorine atom is used as an accelerating material for precipitating liquid crystal molecules as a liquid crystal phase and as a material for adjusting matching of optical characteristics between the liquid crystal phase and the polymer resin phase. The compound is further mixed with the acrylate compound. Examples of the (meth) acrylate compound containing a fluorine atom include (meth) acrylate compounds represented by the general formula (I).

Specific examples include trifluoroethyl acrylate, tetrafluoropropyl acrylate, hexafluorobutyl acrylate, octafluoropentyl acrylate, perfluorooctylethyl acrylate and their methacrylates. Of course, polyfunctional acrylates other than those exemplified are also used. Since the fluorine atom-containing acrylate compound is hard to dissolve in liquid crystal molecules, it is necessary to use the acrylate compound in such a range that the liquid crystal does not unnecessarily precipitate when used by mixing with other acrylate compounds.

For that purpose, 2 out of all acrylate compounds are used.
The content of fluorine atoms after curing is 1 to 10%, preferably 1 to 5%.
Adjusted to.

Examples of the curing agent for curing the EOA and other monofunctional and / or polyfunctional acrylate compounds and acrylate compounds of fluorinated acrylates by irradiating them with ultraviolet rays include acetophenone photoinitiators (manufactured by Merck Ltd.). "Darocure 1173 or" Irgacure "manufactured by Ciba-Geigy Co., Ltd.) can be mentioned.

Of course, the present invention is not limited to this, and a sensitizer, chain transfer agent, dye, etc. can be added.

The amount of the curing agent used is usually preferably about 1 to 5% by weight based on the total amount of acrylate compounds.

As the liquid crystal component constituting the liquid crystal phase, a cyanobiphenyl liquid crystal component having a high dielectric anisotropy and a refractive index difference between the ordinary light refractive index and the extraordinary light refractive index of 0.2 or more is preferably used. Be done. Of course, the liquid crystal component is not limited to this, and depending on the application, not only a nematic liquid crystal such as phenylcyclohexane type, phenylpyrimidine type, benzoic acid ester type or the like, but not only positive dielectric anisotropy but also negative dielectric anisotropy A single liquid or a mixture of liquid crystals and smectic liquid crystals is used.

Since the liquid crystal composition is such that an opaque state appears due to the scattering of light by the minute liquid crystal phase dispersed in the cured resin and the random orientation of the liquid crystal molecules, the liquid crystal droplets in the liquid crystal film and its aggregates. And / or liquid crystal 3
The average size of the dimensional mesh continuous phase has an average diameter of 0.8 μm or more, which is larger than the wavelength of visible light, and is 10 μm.
Hereafter, it is more preferably 5 μm or less. Further, in order to obtain opacity due to the randomness of the liquid crystal molecules, it is better that the difference between the ordinary light refractive index and the above light refractive index is larger.

In general, even a liquid crystal film formed by coating a resin and liquid crystal in an appropriate mixture can show some optical change depending on the presence or absence of voltage application. However, good ON-O
FF characteristics, that is, the haze value when voltage is small is 20% or less when a low potential such as 20 V is applied, and the haze value when no voltage is applied is large, for example, 80% or more. In order to obtain the liquid crystal structure as shown, an optimum combination of liquid crystal and resin is required.

The cyanobiphenyl-based liquid crystal droplets dispersed in the resin of the monofunctional or polyfunctional (meth) acrylate compound in which the fluorine atom-containing (meth) acrylate compound of the present invention is mixed are represented by the general formula: (IV)

[0027]

[Chemical 4] A cyanobiphenyl compound represented by the formula [wherein each X represents an alkyl or alkoxy group having 1 to 12 carbon atoms] is most suitable. You may use these compounds in combination of 2 or more type.

The liquid crystal is, for example, E manufactured by BDH
-8 liquid crystal can be mentioned.

The cyanobiphenyl liquid crystal phase in the liquid crystal film of the present invention comprises cyanobiphenyl liquid crystal in an acrylate monomer mixture, and the liquid crystal component is preferably 50% by weight or more.
By mixing so as to be 5% by weight or less and using this as a coating liquid, liquid crystal droplets having an average diameter of 0.8 μm or more and 5 μm or less, their aggregates and / or a three-dimensional network continuous phase of liquid crystals are obtained. I can do things.

When the content of the liquid crystal component is less than 50% by weight, the liquid crystal phase generated by phase separation from the liquid crystal component dissolved in the raw material acrylate compound mixture during the resin formation becomes small, so that good opacity, that is, light shielding property is obtained. However, there is a drawback that it may not be obtained. Furthermore, during use as a dimming application, generation of bubble-like portions that do not respond to voltage application may occur in the liquid crystal film.

On the other hand, when the content exceeds 75% by weight, the liquid crystal component cannot be completely dissolved in the raw material (meth) acrylate, and minute droplets are formed from the time of mixing the monomers, and the liquid crystal component is further contained in the resin due to curing. Will ooze out. As a result, inconveniences such as a decrease in adhesiveness with the transparent conductive electrode and a decrease in workability occur.

As described above, in order to form a liquid crystal film having good light-shielding property, workability and durability, the liquid crystal component is preferably 50% by weight or more and 75% by weight or less. In order to obtain a more preferable light-shielding property, the liquid crystal component is 55 to 75% by weight.

The liquid crystal film can also be formed by mixing a microencapsulated cyanobiphenyl liquid crystal with an acrylate monomer mixture and using this as a coating liquid and then curing it.

The liquid crystal film can also be formed by impregnating a resin, which has been made into a porous film, with a cyanobiphenyl liquid crystal.

Next, the liquid crystal composition of the present invention will be described.

The overall structure of the liquid crystal structure of the present invention is, as shown in FIG. 1, a (transparent) substrate 1 which is relatively arranged on both sides.
A liquid crystal film 30 made of (transparent) resin in which liquid crystal molecules are dispersed by (transparent) conductive electrode layers 20 and 20 provided on 0 and 10 respectively is sandwiched.

A polyester film having excellent transparency is preferably used as the (transparent) substrate 10 of the present invention, but a glass plate or another transparent polymer film can also be used.

Further, it is provided on the substrate 10 (transparent).
The conductive electrode layer 20 is preferably an indium oxide film made of indium that may contain a small amount of impurities such as tin, but a metal oxide layer such as zinc oxide or titanium oxide;
It is also possible to use a thin film of a metal such as gold or platinum; a laminate in which a thin metal film is sandwiched by a transparent dielectric film.

Although one of the electrode layers 20 may be a non-transparent film having a high reflectance by forming a thick metal film, the substrate 10 may not be transparent in this case.

A resistance of 500 Ω / □ or less is formed on the transparent substrate 10 by a known physical method such as sputtering.
Preferably, the transparent conductive electrode layer 20 having a resistance of 300Ω / □ or less can be provided.

In the liquid crystal structure of the present invention, the transparent conductive electrode layer 20 is provided on the transparent substrate 10 by a known method such as sputtering, and a mixed liquid (coating liquid) of the acrylate monomer mixture and the cyanobiphenyl liquid crystal is coated. Solution) on the transparent conductive electrode layer 20 with a bar coater to a uniform thickness, and then another transparent substrate 1 with the transparent conductive electrode layer 20.
0 is superposed such that the transparent conductive electrode layer 20 is in contact with the liquid crystal layer 30 to obtain a laminated body, and then the laminated body is irradiated with ultraviolet rays under an ultraviolet irradiation device using, for example, a mercury lamp as a light source to obtain an acrylate monomer. It can be cured and manufactured.

In order to apply the coating liquid to a uniform thickness,
Printing methods other than the bar coater method are also used.

In some cases, it is necessary to adjust the viscosity of the liquid crystal mixture in order to facilitate printing. In this case, while the liquid crystal mixture is being stirred, ultraviolet rays or the like are irradiated for an appropriate time and a part of it is irradiated. A method of curing is also effective.

The liquid crystal film 30 cured by a method such as UV irradiation has a thickness of 2 to 30 μm, but the opacity of the liquid crystal film in the state where no voltage is applied on the transparent conductive electrode layer 20 and the voltage application. It is selected in consideration of the transparency when doing. Preferably, a thickness of 5-20 μm is used.

The liquid crystal structure thus obtained has excellent durability and is easy to manufacture, and has excellent ON-OFF characteristics, that is, transparency with a haze value of 20% or less when a voltage of 20 V is applied, and a voltage of 20% or less. It has a large haze value of 80% or more when no voltage is applied, has a large difference between transparency and opacity, can be driven at a low voltage, and can be suitably used for light control materials such as liquid crystal shutters and display materials.

[0046]

The present invention will be described in more detail with reference to the following examples.

[0047]

Example 1 A 125 μm-thick polyester film was used as a transparent substrate, and an indium oxide film containing a small amount of tin as a transparent conductive layer was deposited thereon by a sputtering method to a thickness of about 200 Å.

E-8 manufactured by BDH was used as the cyanobiphenyl liquid crystal, and M113 (Norylphenol tetraethylene oxide acrylate) manufactured by Toagosei Co., Ltd. was used as the acrylate monomer. As a fluorine-based acrylate compound, F-8 manufactured by Kyoeisha Yushi Kagaku Kogyo
(Octafluoropentyl acrylate) was used. These compounds are mixed in a weight ratio of M113: HOPA: F-.
The mixture was mixed at a ratio of 8 = 64: 16: 20. As a curing agent, 3% by weight of Irgacure manufactured by Ciba Geigy was added and mixed.

After mixing so that the liquid crystal component was 67% by weight, the liquid was stirred well and deaerated to obtain a coating liquid.

Next, the coating liquid was applied onto the transparent conductive layer using a # 20 bar coater.

Next, another polyester film with a transparent conductive layer was laminated so that the transparent conductive layer was in contact with the liquid crystal coating film, and then 6 mW / cm ² was applied using an ultraviolet irradiator having a mercury lamp as a light source. Of ultraviolet light for about 10 minutes.
The liquid crystal coating layer was cured between the transparent conductive layers by ultraviolet light to form a liquid crystal film of about 15 μm to form a liquid crystal constituent.

0 V is applied between the two electrodes of the obtained liquid crystal structure.
A voltage of 40 V was applied to measure the transmittance. The result is shown in FIG. 2 as the change of the parallel light transmittance at 600 nm.
It was shown to. It can be seen that the liquid crystal structure of the present invention causes a large change in transmittance at 0V-10V.

[0053]

Comparative Example 1 Urethane acrylate oligomer having an average molecular weight of 5,000 to 6,000 (manufactured by Negami Kogyo Co., Ltd., UN
Using a resin obtained by curing -1010) by ultraviolet irradiation as a transparent resin, the voltage dependence of the liquid crystal construct prepared by the same method as in Example 1 was examined. The results are also shown in FIG.

As is apparent from FIG. 2, the liquid crystal structure of the present invention has a feature that it can be driven at a low potential.

[0055]

INDUSTRIAL APPLICABILITY The present invention is a liquid crystal structure which can be easily manufactured, has excellent durability, and can be driven at a low potential, and can be widely used as a liquid crystal shutter, a compounding material or a display material.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a liquid crystal structure of the present invention.

FIG. 2 is a graph showing the transmittance dependency when a voltage of 0 to 100 V is applied to the liquid crystal structure of Example 1.

[Explanation of symbols]

 10 Transparent Substrate 20 Transparent Conductive Electrode Layer 30 Liquid Crystal Film

Claims (5)

[Claims] 1. A resin film containing 1 to 10% (based on the number of atoms) of fluorine atoms, and liquid crystal droplets having a diameter of 0.5 to 5 μm, which are dispersed in the resin film, their aggregates and / or liquid crystals. A liquid crystal film consisting of a three-dimensional mesh continuous phase. 2. The liquid crystal film according to claim 1, wherein the resin film is a film made of an acrylate resin and having a thickness of 2 to 30 μm. 3. The liquid crystal film according to claim 2, wherein the acrylate resin is a polymer of a (meth) acrylate compound containing no fluorine atom and a (meth) acrylate compound containing a fluorine atom. 4. The (meth) acrylate compound containing a fluorine atom is represented by the following formula (I): [Wherein, R represents -H or -CH ₃ , and n is 1 to
10, x represents 0 to 2n, and y represents (2n + 1) -x. ] The liquid crystal film of Claim 3 which is a compound represented by these. 5. The liquid crystal film according to any one of claims 1 to 4, which is disposed between a first electrode made of a transparent conductive layer and a second electrode made of a conductive layer in electrical contact therewith. Liquid crystal composition.