JPH0593900A - Liquid crystal device - Google Patents

Abstract

(57) [Summary] [Structure] At least one transparent substrate having an electrode layer and a substrate of the general formula (1) (In the formula, m and n are each independently an integer of 1 to 10, k:
A light-scattering liquid crystal device having a light control layer composed of a transparent solid substance obtained by polymerizing a polymerizable composition containing a compound of 1 to 5) and a liquid crystal composition. [Effect] This liquid crystal device has high adhesion between a flexible substrate such as a plastic film and the transparent solid substance in the light control layer, and is excellent in electro-optical characteristics such as contrast, threshold voltage, and steepness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal encapsulating thin film which does not use a polarizing plate, and more specifically, it can electrically control the blocking and transmission of a visual field, and particularly, it can be used for building windows and show windows. Is used as a screen to block the field of view,
Further, by displaying characters or figures and electrically switching the display with high-speed response, a decorative display board such as an advertising board, a clock, a display device of a calculator, or a display device requiring a bright screen, for example, The present invention relates to a liquid crystal device used as a display device of a computer terminal or a display device of a projection.

[0002]

2. Description of the Related Art Conventionally, liquid crystal devices are of TN (twisted nematic) type using nematic liquid crystal,
The STN (Super Twisted Nematic) type has been put into practical use. Also, a liquid crystal device using a ferroelectric liquid crystal has been proposed.

Since these require a polarizing plate, there is a limit in brightening the screen, and since they require an alignment treatment, there is a problem that the yield at the time of producing a display device is reduced.

On the other hand, as a method for producing a liquid crystal device which does not require a polarizing plate or an alignment treatment and is bright and has good contrast, a method is known in which liquid crystal droplets are dispersed in a polymer and the polymer is formed into a film.

However, in a liquid crystal device in which liquid crystal droplets are dispersed in a polymer, sufficient transparency can be obtained in addition to the trouble of optimizing the matching and non-matching of the individual refractive indexes of the liquid crystal material and the polymer. It requires a high voltage of 25 V or more and does not have the low drive voltage characteristics that are important in the practical application of display devices.

As a technique that enables low-voltage drivability, which is an important characteristic required for practical use of this liquid crystal display device, as well as high contrast and time-division drivability, Japanese Patent Laid-Open No. 63-
No. 240460 discloses a liquid crystal device having a structure in which a transparent solid substance is distributed in a three-dimensional network in a continuous layer of a liquid crystal material.

[0007]

However, in the above liquid crystal device, since the transparent solid substance is distributed in a three-dimensional network and the content of the liquid crystal material is high, low voltage drivability is achieved and the light control layer is obtained. Although the adhesiveness between the transparent solid substance and the glass substrate is good, there is a problem in that the adhesiveness is poor when a flexible substrate such as a plastic film is used and a highly reliable liquid crystal device cannot be produced.

Further, in the method in which liquid crystal droplets are dispersed in a polymer and the polymer is formed into a film, the adhesion is high when a flexible substrate such as a plastic film is used, but the driving voltage is as high as 25 V or more. Needing a voltage.

The problem to be solved by the present invention is to provide a liquid crystal device which has improved adhesion when a flexible substrate such as a plastic film is used and has a low voltage drivability.

[0010]

In order to solve the above-mentioned problems, the inventors of the present invention have extensively studied a polymerizable composition forming a transparent solid substance, and as a result, have used a flexible substrate such as a plastic film. In this case, the adhesiveness has been increased, and a highly reliable liquid crystal device has been produced.

That is, to solve the above problems, the present invention provides, as a first liquid crystal device, two substrates having at least one electrode layer having transparency, and a light control layer supported between the substrates. In the light-scattering liquid crystal device, wherein the light control layer comprises a transparent solid substance and a liquid crystal material,
The transparent solid substance has the general formula (1)

[0012]

[Chemical 4]

(Wherein R represents a hydrogen atom or a methyl group, m and n each independently represent an integer of 1 to 10, and k represents an integer of 1 to 5). Provided is a liquid crystal device, which is a transparent solid substance formed by polymerizing a polymerizable composition.

The present invention also provides a second liquid crystal device, wherein in the first liquid crystal device, the transparent solid substance is a compound of the above general formula (1) and a general formula (2).

[0015]

[Chemical 5]

(In the formula, p and q are each independently 1 to 1
Represents an integer of 0. And a liquid crystal device which is a transparent solid substance obtained by polymerizing a polymerizable composition comprising a bifunctional acrylate represented by the formula (1).

Furthermore, the present invention is a third liquid crystal device, wherein in the first liquid crystal device, the transparent solid substance is a compound of the above general formula (1) and a general formula (3).

[0018]

[Chemical 6]

(In the formula, t represents an integer of 2 to 20.)
There is provided a liquid crystal device which is a transparent solid substance formed by polymerizing a polymerizable composition comprising a bifunctional acrylate represented by

Furthermore, the present invention is the fourth liquid crystal device, wherein in the first liquid crystal device, the transparent solid substance is a compound represented by the above general formula (1), a compound represented by the above general formula (2) and the above general formula. A liquid crystal device which is a transparent solid substance obtained by polymerizing a polymerizable composition comprising a compound represented by (3).

The first liquid crystal device of the present invention is, for example,
It can be manufactured as follows. That is, a polymerizable composition containing a compound of the general formula (1) and a liquid crystal material, at least one of which has an electrode layer and is transparent, and a polymerization initiator, a chain transfer agent, if necessary, By interposing a light control layer constituent material containing a photosensitizer and a dye cross-linking agent, and irradiating ultraviolet rays through a transparent substrate,
By polymerizing the polymerizable composition, a liquid crystal device having a light control layer composed of a transparent solid substance and a liquid crystal material can be manufactured.

Similarly, the second, third and fourth aspects of the present invention are provided.
Liquid crystal devices can also be manufactured. A material having flexibility, such as a plastic film, is particularly useful for the substrate used in the present invention, but a rigid material such as glass or metal may be used. And
Two substrates are opposed to each other and are separated by an appropriate distance.

At least one of them has transparency, but complete transparency is not essential. If the liquid crystal device is used to act on light passing from one side of the device to the other, both substrates will be provided with appropriate transparency.

On this substrate, appropriate transparent or opaque electrodes may be arranged entirely or partially on the substrate depending on the purpose. It should be noted that a spacer for holding a space can be usually interposed between the two substrates, as in a known liquid crystal device.

When the liquid crystal device of the present invention is used in a display device of a computer terminal, a display device of a projection or the like, it is preferable to provide an active element on the electrode layer. The transparent solid substance in the light control layer may be a fibrous or particle-like dispersed substance or a film-like substance in which a liquid crystal material is dispersed in a droplet form, but it has a three-dimensional network structure. Is more preferable.

Further, the liquid crystal material preferably forms a continuous layer, which is indispensable for forming an optical boundary surface by forming a disordered state of the liquid crystal material and expressing light scattering.

In the liquid crystal device of the present invention, if the average diameter of the liquid crystal droplets or the average diameter of the shape of the transparent solid substance is too large or too small as compared with the wavelength of light, the light scattering property tends to deteriorate. , 0.2-2 μm is preferable. In addition, the thickness of the layer having a light-scattering property is set to a substrate interval of 2 to 40 μm in order to obtain a sufficient contrast between the opacity due to light scattering and the electrically achieved transparency, depending on the purpose of use. Is preferable, and a range of 6 to 25 μm is particularly preferable.

The compound of the general formula (1) used in the present invention is available as a commercial product, and examples thereof include "BS-101" manufactured by Arakawa Chemical Industry Co., Ltd. The compound represented by the general formula (2) used in the present invention is available as a commercial product, and for example, “HX-620” and “HX manufactured by Nippon Kayaku Co., Ltd.
-220 "and the like.

The compound represented by the general formula (3) used in the present invention is commercially available, and examples thereof include "C-2000" manufactured by Sartomer. The liquid crystal material used in the present invention does not need to be a single liquid crystal compound, and may be a mixture containing two or more kinds of liquid crystal compounds or substances other than the liquid crystal compound. Any material recognized as a liquid crystal material in the field may be used, and one having a positive dielectric anisotropy is preferred. The liquid crystal used is preferably a nematic liquid crystal, a smectic liquid crystal or a cholesteric liquid crystal, and a nematic liquid crystal is particularly preferable. In order to improve its performance, cholesteric, chiral nematic liquid crystal, chiral smectic liquid crystal and the like and chiral compounds may be appropriately contained.

The liquid crystal material used in the present invention is preferably a blended composition comprising one or more compounds selected from the compound group shown below, and the characteristics of the liquid crystal material, that is, the phase of the isotropic liquid and the liquid crystal. To be selected and blended appropriately for the purpose of improving the transition temperature, melting point, viscosity, Δε (dielectric anisotropy), Δn (refractive index anisotropy), and solubility with transparent solid substances. You can

Examples of the liquid crystal material include 4-substituted benzoic acid 4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted biphenyl ester, 4- (4-substituted cyclohexanecarbonyloxy)
Benzoic acid 4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted cyclohexyl ester, 4-substituted 4'-substituted Biphenyl, 4-substituted phenyl 4'-substituted cyclohexane, 4
-Substituted 4 "-substituted terphenyl, 4-substituted biphenyl 4'-substituted cyclohexane, 2- (4-substituted phenyl)
Examples thereof include -5-substituted pyridine, and among these compounds, a compound having a cyano group at least at one end of the molecule is particularly preferable.

As a method for forming a uniform light control layer containing a transparent solid substance, for example, (1) a liquid crystal material, a polymer-forming monomer or oligomer, and, if necessary, a photopolymerization initiator are uniformly added. The solution, or (2) a uniform solution of a solvent, a polymer-forming monomer or oligomer, and optionally a photopolymerization initiator is sandwiched between two substrates having electrode layers, or one of It is also possible to coat the above substrate using a coater such as a spin coater, and then overlay the other substrate, which is irradiated with ultraviolet rays or thermally polymerized and cured.

Examples of the polymerization initiator that can be used in the present invention include 2-hydroxy-2-methyl-1-
Phenylpropan-1-one (Merck's "Darocur
1173 "), 1-hydroxycyclohexyl phenyl ketone (" Irgacure 184 "manufactured by Ciba-Geigy), 1-
(4-Isopropylphenyl) -2-hydroxy-2-
Methylpropan-1-one (Merck & Co. "Darocur 11
16 "), benzyl dimethyl ketal (" Irgacure 651 "manufactured by Ciba-Geigy), 2-methyl-1- [4-
(Methylthio) phenyl] -2-morpholinopropanone-1 (“Irgacure 907” manufactured by Ciba-Geigy),
A mixture of 2,4-diethylthioxanthone (“Kayacure DETX” manufactured by Nippon Kayaku Co., Ltd.) and ethyl p-dimethylaminobenzoate (“Kayacure EPA” manufactured by Nippon Kayaku Co., Ltd.), isopropyl thioxanthone (“Kayakyua Sup Co.” Cantacure ITX ") and ethyl p-dimethylaminobenzoate and the like, but liquid 2-hydroxy-2-methyl-1-phenylpropan-1-one is a liquid crystal material, a polymer-forming monomer or Particularly preferred in terms of compatibility with the oligomer.

[0034]

EXAMPLES Examples of the present invention will be shown below to further illustrate the present invention.
This will be specifically described. However, the present invention does
It is not limited to the examples. The following examples and
In the comparative examples, "%" means "% by weight". Also, each
Each of the evaluation characteristics in the examples means the following symbols and contents
To do. (1) V₉₀, V_Ten: Light transmission of liquid crystal device when no voltage is applied
Rate (T₀) Is set to 0%, and light is transmitted as the applied voltage increases.
Transmittance (T₁₀₀) As 100%
The applied voltage (V), which gives a light transmittance of 90%,₉₀, Light transparent
The applied voltage when the excess rate is 10% is V _TenAnd (2) Contrast: State where the device is removed from the metering
The light transmittance when the light source is on is 100%, and the light when it is off
When the transmittance is 0%, the applied voltage V₉₀And V_TenGet at
The light transmittance is T₉₀And T_TenWhen
Trust = T₉₀/ T_TenAnd (3) Response speed: The applied voltage was switched from 0V to the ON state
When rising the time until the light transmittance reaches 90%
Time τ_rAnd when the ON state is switched to 0V, light is transmitted.
Fall time τ when the rate reaches 10%_dWhen
And change the voltage in the ON state,_r= Τ_dBecomes
Let time be the response speed. (Example 1)

[0035]

[Chemical 7]

A liquid crystal composition (A) consisting of was prepared. The properties of this liquid crystal composition (A) were as follows. Transition temperature 68.5 ℃ (N-I) < -70 ℃ (C-N) refractive index anisotropy _{n e = 1.787 n o = 1.533} Δn = 0.254 dielectric anisotropy [Delta] [epsilon] = 26.9 The liquid crystal composition (A) 80 %, As a polymerizable composition "BS
-101 "(Arakawa Chemical Industry Co., Ltd., rosin epoxy acrylate) 5.94%," HX-620 "(Nippon Kayaku Co., Ltd., caprolactone-modified hydroxypivalic acid ester neopentyl glycol diacrylate) 13 .86
%, As a polymerization initiator, 2-hydroxy-2-methyl-
Two polyester films each having a 5 × 5 cm ITO electrode layer in which a light control layer forming material consisting of 1% of 1-phenylpropan-1-one was dispersed in a small amount on the electrode layer with a spacer having an average particle diameter of 10 μm ( The polymerizable composition was cured (polymerized) by sandwiching it between SEIC K-LC manufactured by Daicel Chemical Industries Ltd. and irradiating with ultraviolet rays.
The curing conditions are as follows: A polyester film sandwiching the light control layer forming material is passed under a metal halide lamp (80 W / cm ² ) at a speed of 3.5 m / min, and an ultraviolet ray of energy equivalent to 500 mJ / cm ² is obtained. Was irradiated.

The obtained liquid crystal device was cut into a 10 mm width,
Two polyester film substrates were pulled by a tensile tester and the T-type peel strength was measured.
A high value of / 10 mm was obtained, and a liquid crystal device having good adhesion between the light control layer and the substrate was obtained.

The characteristics of the obtained liquid crystal device were as follows. _{V 10: 3.9V V 90: 9.8V} γ: 2.5 _{Contrast: 1:29 τ r = τ d:} 10.0 in milliseconds (Comparative Example 1) Example 1, "HX-620" 19. 8%
A liquid crystal device was obtained in the same manner as in Example 1 except that the polymerizable composition consisting of

The T-type peel strength of the obtained liquid crystal device was measured in the same manner as in Example 1 and found to be 1 g / 10 mm. This liquid crystal device is unstable when the substrate is bent, and requires a reinforcing means for practical use.

The characteristics of the obtained liquid crystal device were as follows. V ₉₀ : 20.0 V Contrast: 1:20 (Comparative Example 2) In Example 1, the liquid crystal composition (A) 60
A liquid crystal device was produced in the same manner as in Example 1 except that a polymerizable composition consisting of wt% and “HX-620” 39.8% was used. The obtained liquid crystal device has low adhesion,
The driving voltage was also high.

From these results, it is clear that the liquid crystal device obtained in Example 1 of the present invention has considerably high adhesion. Therefore, it can be understood that the use of the polymerizable composition containing the compound of the general formula (1) improves the adhesion with the polyester film and also improves the electro-optical characteristics. (Example 2) In Example 1, 3.96% of "BS-101"
And a liquid crystal device was obtained in the same manner as in Example 1 except that a polymerizable composition consisting of 15.84% of "HX-620" was used.

The T-type peel strength of the obtained liquid crystal device was measured in the same manner as in Example 1 and found to be 100 g / 10 mm.
I got a high value. The characteristics of the obtained liquid crystal device were as follows.

V ₁₀ : 5.7V V ₉₀ : 10.9V γ: 1.9 Contrast: 1:48 τ _r = τ _d : 10.0 milliseconds (Example 3) In Example 1, the "BS-101 "1.98%
And a liquid crystal device was obtained in the same manner as in Example 1 except that a polymerizable composition consisting of 17.82% of “HX-620” was used.

The T-type peel strength of the obtained liquid crystal device was measured in the same manner as in Example 1, and a high value of 50 g / 10 mm was obtained. The characteristics of the obtained liquid crystal device were as follows.

V ₁₀ : 6.2V V ₉₀ : 11.8V γ: 1.9 Contrast: 1:43 τ _r = τ _d : 10.0 milliseconds (Example 4) In Example 1, the "BS-101 A liquid crystal device was obtained in the same manner as in Example 1 except that a polymerizable composition consisting of 9.9% and "C-2000" (manufactured by Sartomer Co., Ltd., long-chain aliphatic diacrylate) was used. It was

The T-type peel strength of the obtained liquid crystal device was measured in the same manner as in Example 1 and found to be 180 g / 10 mm.
I got a high value. The characteristics of the obtained liquid crystal device were as follows.

V ₁₀ : 5.9V V ₉₀ : 10.6V γ: 1.8 Contrast: 1:25 τ _r = τ _d : 10.0 milliseconds (Comparative Example 3) In Example 4, "C-2000" was used. "19.8%
A liquid crystal device was obtained in the same manner as in Example 4 except that the polymerizable composition consisting of

The T-type peel strength of the obtained liquid crystal device was measured in the same manner as in Example 1 and found to be 1 g / 10 mm. This liquid crystal device is unstable when the substrate is bent, and requires a reinforcing means for practical use.

The characteristics of the obtained liquid crystal device were as follows. V ₉₀ : 40.0 V Contrast: 1:20 (Comparative Example 4) In Example 4, the liquid crystal composition (A) 60
% And “C-2000” 39.8%, a liquid crystal device was prepared in the same manner as in Example 4.

The obtained liquid crystal device has low adhesion and
The driving voltage was also high. From this result, it is clear that the liquid crystal device obtained in Example 3 of the present invention has considerably high adhesion. Therefore, it can be understood that the use of the polymerizable composition containing the compound of the general formula (1) improves the adhesion with the polyester film and also improves the electro-optical characteristics. (Example 5) In Example 1, "BS-101" 7.92%
And a liquid crystal device was obtained in the same manner as in Example 1 except that a polymerizable composition containing 11.88% of "C-2000" was used.

The T-type peel strength of the obtained liquid crystal device was measured in the same manner as in Example 1 and found to be 130 g / 10 mm.
I got a high value. The characteristics of the obtained liquid crystal device were as follows.

V ₁₀ : 6.5V V ₉₀ : 11.6V γ: 1.8 Contrast: 1:25 τ _r = τ _d : 10.0 milliseconds (Example 6) In Example 1, the "BS-101 "5.94%
And a liquid crystal device was obtained in the same manner as in Example 1 except that a polymerizable composition containing 13.86% of "C-2000" was used.

The T-type peel strength of the obtained liquid crystal device was measured in the same manner as in Example 1, and a high value of 80 g / 10 mm was obtained. The characteristics of the obtained liquid crystal device were as follows.

V ₁₀ : 7.2V V ₉₀ : 13.4V γ: 1.9 Contrast: 1:25 τ _r = τ _d : 10.0 milliseconds

[0055]

The liquid crystal device of the present invention has a very high adhesion between the transparent solid substance and the substrate when a flexible substrate such as a plastic film is used, and further, a polarizing plate is unnecessary, and a liquid crystal of a bright image quality is obtained. The device is a light-scattering liquid crystal device having a large transparent-opaque contrast of about 1:25 or more, a threshold voltage characteristic capable of time-division driving, and steepness.

Therefore, the liquid crystal device of the present invention is extremely useful as a light control glass, a display device for computer terminals, and a display element for projection.

Claims (7)

[Claims] 1. At least one transparent substrate having an electrode layer, and a dimming layer supported between the substrates,
In the liquid crystal device in which the light control layer is composed of a transparent solid substance and a liquid crystal material, the transparent solid substance is represented by the general formula (1): (In the formula, R represents a hydrogen atom or a methyl group, and m and n
Each independently represents an integer of 1 to 10, and k is 1 to 5
Represents the integer. ) A liquid crystal device, which is a transparent solid substance obtained by polymerizing a polymerizable composition containing a compound represented by the formula (1). 2. The transparent solid substance comprises a compound represented by the general formula (1) according to claim 1 and a general formula (2): A transparent solid substance obtained by polymerizing a polymerizable composition comprising a bifunctional acrylate represented by the formula (wherein p and q each independently represent an integer of 1 to 10). Liquid crystal device. 3. The transparent solid substance is a compound represented by the general formula (1) according to claim 1 or a compound represented by the general formula (3): The liquid crystal device according to claim 1, which is a transparent solid substance formed by polymerizing a polymerizable composition comprising a bifunctional acrylate represented by the formula (wherein t represents an integer of 2 to 20). 4. The transparent solid substance is a compound represented by the general formula (1) according to claim 1, a compound represented by the general formula (2) according to claim 2, and a general formula (3) according to claim 3. The liquid crystal device according to claim 1, which is a transparent solid substance obtained by polymerizing a polymerizable composition comprising a bifunctional acrylate represented by the formula (1). 5. The light control layer is a light control layer made of a transparent solid substance having a three-dimensional network structure having continuous fine pores and a liquid crystal material filling the continuous fine pores. The described liquid crystal device. 6. The liquid crystal device according to claim 1, 2, 3, 4 or 5, wherein a liquid crystal material exhibiting positive dielectric anisotropy is used. 7. The liquid crystal device according to claim 1, 2, 3, 4, 5, or 6, wherein the thickness of the light control layer is 2 to 40 μm.