JP3116493B2 - Liquid crystal device - Google Patents

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 that does not use a polarizing plate, and more particularly to a device capable of electrically controlling the blocking and transmission of a visual field, particularly, for example, a building window and a show window. It is used for screens that block the visual field, displays characters and graphics, and switches the display electrically with high-speed responsiveness. The present invention relates to a display device requiring a screen, for example, 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 Japanese Patent Laid-Open Publication No. Sho 63 (1988) discloses a technology which enables low voltage driving, high contrast and time division driving which are important characteristics required for practical use of a liquid crystal display device.
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.

[0003]

However, the above-mentioned liquid crystal device has a problem that, although low-voltage drivability is achieved, a liquid crystal device having low resistance and high reliability cannot be manufactured.

Further, the above-mentioned liquid crystal device exhibits a hysteresis phenomenon in which the transmittance when the voltage rises and the transmittance when the voltage falls have different values in the electro-optical characteristics, which reduces the margin of time-division driving and performs gradation display. This is extremely problematic.

An object of the present invention is to provide a liquid crystal device having a high resistance and a high voltage holding ratio, a low voltage drivability, and a small hysteresis width.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies on a polymerizable composition forming a transparent solid substance, and as a result, have increased the resistance and the voltage holding ratio and reduced the resistance. This led to the production of a liquid crystal device having a voltage drivability and a small hysteresis width.

That is, in order to solve the above-mentioned problems, the present invention provides, as a first liquid crystal device, two substrates each having an electrode layer and at least one of which is transparent, and a dimming layer supported between the substrates. Having a light-scattering type liquid crystal device, wherein the light control layer comprises a transparent solid substance and a liquid crystal material,
The transparent solid substance has a general formula (1)

[0008]

Embedded image

(Wherein, i, j, k and l each independently represent an integer of 0 to 10), a transparent solid substance obtained by polymerizing a polymerizable composition containing a bifunctional acrylate. A liquid crystal device is provided.

According to the present invention, as a second liquid crystal device, in the first liquid crystal device, the transparent solid substance is a compound of the general formula (1) and a compound of the general formula (2)

[0011]

Embedded image

(Wherein m, n, p and q each independently represent an integer of 0 to 10). Transparency obtained by polymerizing a polymerizable composition containing a bifunctional acrylate represented by the following formula: Provided is a liquid crystal device which is a solid substance.

Further, according to the present invention, as a third liquid crystal device, in the first liquid crystal device, a transparent solid substance is provided.
The compound of the above general formula (1), the compound of the above general formula (2) and the general formula (3)

[0014]

Embedded image

(Wherein r, s, t and u each independently represent an integer of 0 to 10). Transparency obtained by polymerizing a polymerizable composition containing a bifunctional acrylate represented by the formula: Provided is a liquid crystal device which is a solid substance.

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, a polymerization initiator, a chain transfer agent, if necessary, are provided between two substrates having at least one electrode layer having transparency. By irradiating a photosensitizer, a light modulating layer constituent material containing a dye crosslinking agent, and irradiating ultraviolet rays through a transparent substrate,
By polymerizing the polymerizable composition, a liquid crystal device having a light modulating layer composed of a transparent solid substance and a liquid crystal material can be manufactured.

Similarly, the second and third liquid crystal devices of the present invention can be manufactured.

The content of the liquid crystal material and the photopolymerizable composition in the light modulating layer forming material is preferably in the range of 60:40 to 90:10 by weight. If the amount of the liquid crystal material is too large or too small, the dispersion state of the liquid crystal material and the transparent solid substance is not uniform, so that the light control function by light scattering is not exhibited, which is not preferable.

The substrate used in the present invention may be a rigid material, for example, glass or metal, or a flexible material, for example, a plastic film. Then, two substrates are opposed to each other and are obtained at an appropriate interval.

Further, at least one of them has transparency, but does not necessarily require complete transparency. If the liquid crystal device is used to act on light passing from one side of the device to the other, both substrates are provided with the appropriate transparency.

On this substrate, an appropriate transparent or opaque electrode may be arranged over the entire surface or partially according to the purpose. Incidentally, a spacer for maintaining a space can be usually interposed between the two substrates, similarly to a well-known liquid crystal device.

When the liquid crystal device of the present invention is used for a display device of a computer terminal or a display device of a projection, it is preferable to provide an active element on the electrode layer.

The transparent solid substance in the light modulating layer may be a substance dispersed in fibrous or particulate form or a film-shaped substance in which liquid crystal material is dispersed in small droplets. Are more preferable.

The liquid crystal material preferably forms a continuous layer, and is indispensable for forming a disordered state of the liquid crystal material to form an optical interface and to scatter light.

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

The compounds represented by the general formulas (1), (2) and (3) used in the present invention are available as commercial products, for example, the general formulas (1), (2) and (3) As a mixture of compounds represented by
U-760 ".

The liquid crystal material used in the present invention need not be a single liquid crystal compound, but may be a mixture containing two or more liquid crystal compounds or substances other than the liquid crystal compound. Usually, any material which is recognized as a liquid crystal material in this technical field may be used, and a material having a positive dielectric anisotropy is preferable. As the liquid crystal used, a nematic liquid crystal, a smectic liquid crystal, and a cholesteric liquid crystal are preferable, and a nematic liquid crystal is particularly preferable. In order to improve the performance, cholesteric, chiral nematic liquid crystal, chiral smectic liquid crystal, or the like, or a chiral compound may be appropriately contained.

The liquid crystal material used in the present invention is preferably a compounded composition comprising at least one compound selected from the following compound group. The properties of the liquid crystal material, that is, the phase of the isotropic liquid and the liquid crystal are preferable. To be appropriately selected, blended and used for the purpose of improving the transition temperature, melting point, viscosity, Δε (dielectric anisotropy), Δn (refractive index anisotropy), solubility with a transparent solid substance, and the like. Can be.

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-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. Among these compounds, compounds having a cyano group at least at one terminal of the molecule are particularly preferable.

The method of forming a light control layer containing a uniform transparent solid substance includes, for example, (1) a method of uniformly preparing a liquid crystal material, a polymer-forming monomer or oligomer, and, if necessary, a photopolymerization initiator. A solution, or (2) a uniform solution of a solvent, a polymer-forming monomer or oligomer, and a photopolymerization initiator, if necessary, is sandwiched between two substrates having an electrode layer, or The substrate may be coated using a coater such as a spin coater, and then the other substrate may be overlaid. The substrate is irradiated with ultraviolet light or thermally polymerized and cured.

The polymerization initiator that can be used in the present invention includes, for example, 2-hydroxy-2-methyl-1-
Phenylpropan-1-one ("Darocur" manufactured by Merck & Co., Ltd.)
1173 "), 1-hydroxycyclohexylphenyl ketone (" Irgacure 184 "manufactured by Ciba-Geigy), 1-
(4-Isopropylphenyl) -2-hydroxy-2-
Methylpropan-1-one ("Darocur 11" manufactured by Merck & Co.)
16)), benzyldimethyl 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.) 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, Particularly preferred is the compatibility with the oligomer.

[0032]

The present invention will be described more specifically below with reference to examples of the present invention. However, the invention is not limited to these examples.

In the following Examples and Comparative Examples, "%" represents "% by weight". In addition, each of the evaluation characteristics in each embodiment means the following symbols and contents. (1) V ₉₀ , V ₁₀ : The light transmittance (T ₀ ) of the liquid crystal device when no voltage is applied is 0%, and the light transmittance (T ₀ ) when the light transmittance does not change with an increase in the applied voltage ₁₀₀ ) to 100%
In this case, the applied voltage when the light transmittance is 90% is V ₉₀ , and the applied voltage when the light transmittance is 10% is V ₁₀ .

(2) Contrast: When the light transmittance of the liquid crystal device when no voltage is applied is T ₀ and the light transmittance obtained when the applied voltage is V ₉₀ is T ₉₀ with the device removed from the photometry, , And contrast = T ₉₀ / T ₀ .

[0035] (3) Response Time: when switching the applied voltage from 0V to the ON state, the light transmittance is the rise time tau _r time to reach 90%, when switching to 0V from the ON state, the light The voltage until the transmittance reaches 10% is defined as the fall time τ _d , and the voltage in the ON state is changed. The time when τ _r = τ _d is defined as the response speed.

(4) Voltage holding ratio: Frame frequency 60 Hz,
A voltage of 4.5 V, a rectangular wave having an ON state time of 67 μs is applied, the charge accumulated in the ON state is measured by Q ₀ , the current leaking in the OFF state is measured by a high impedance voltmeter, and the remaining charge is measured by Q
Where, voltage holding ratio = Q / Q ₀ .

(5) Hysteresis: When the voltage is increased from 0 V, the voltage at which the light transmittance becomes 50% (T ₅₀ ) is V _50.
^UP , light transmittance is 5 when lowered from a sufficiently high voltage
When the voltage at which the voltage becomes 0% is V ₅₀ ^DOWN , ΔV = V ₅₀ ^UP− V ₅₀ ^DOWN is used as the evaluation value of the hysteresis phenomenon and the hysteresis width is used.

(Example 1)

[0039]

Embedded image

A liquid crystal composition (A) was prepared. Various properties of this liquid crystal composition (A) were as follows. Transition temperature 66.3 ℃ (N-I) < -50 ℃ (C-N) refractive index anisotropy _{n e = 1.708 n o = 1.512} Δn = 0.196 dielectric anisotropy [Delta] [epsilon] = 13 .8

80% of the liquid crystal composition (A) and "KU-760" (manufactured by Arakawa Chemical Industries) as a polymerizable composition.
A light modulating layer forming material composed of 8% and 0.2% of “Darocur 1173” (manufactured by Merck, 2-hydroxy-2-methyl-1-phenylpropan-1-one) as a polymerization initiator was used. The polymerizable composition was polymerized by sandwiching it between two glass plates having a 5 × 5 cm ITO electrode layer in which a small amount of a 10 μm spacer was sprayed on the electrode layer, and irradiated with ultraviolet rays. The polymerization conditions were as follows: a glass plate holding a dimming layer forming material was passed under a metal halide lamp (80 W / cm ² ) at a speed of 3.5 m / min to obtain 500 mJ.
The liquid crystal device was obtained by irradiating ultraviolet rays having energy corresponding to / cm ² .

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device were as follows. V ₁₀ : 4.4 V V ₉₀ : 8.6 V γ: 2.0 Contrast: 1:29 τ _r = τ _d : 10.0 ms Voltage holding ratio: 92% Hysteresis: 0.2 V

Comparative Example 1 In Example 1, instead of using 19.8% of “KU-760” as the polymerizable composition, “KAYARAD-HX620” (manufactured by Nippon Kayaku Co., Ltd.)
A liquid crystal device was obtained in the same manner as in Example 1, except that 19.8% of caprolactone-modified hydroxypivalic acid ester neopentyl glycol diacrylate) was used.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device were as follows. V ₉₀ : 17.2 V Contrast: 1:20 Voltage holding ratio: 80% Hysteresis: 1.0 V

From these results, it is clear that the resistance and the voltage holding ratio of the liquid crystal device obtained in Example 1 of the present invention are considerably high. Therefore, it can be understood that the use of the polymerizable composition containing the compound of the general formula (1) improves the resistance and the voltage holding ratio and also improves the electro-optical characteristics.

Example 2 Instead of using 19.8% of "KU-760" as the polymerizable composition in Example 1, 13.8% of "KU-760" and "LA" (Kyoei A liquid crystal device was obtained in the same manner as in Example 1, except that 6.0% of lauryl acrylate (manufactured by Chemical Industry Co., Ltd.) was used.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device were as follows. V ₁₀ : 2.0 V V ₉₀ : 4.0 V γ: 2.0 Contrast: 1:29 τ _r = τ _d : 10.0 ms Voltage holding ratio: 93% Hysteresis: 0.2 V

Comparative Example 2 Example 2 was repeated except that 13.8% of “KAYARAD-HX620” was used instead of 13.8% of “KU-760” as the polymerizable composition. A liquid crystal device was obtained in the same manner as described above.

When the dimming layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device were as follows. V ₉₀ : 7.2 V Contrast: 1:20 Voltage holding ratio: 80% Hysteresis: 1.0 V

From these results, it is clear that the resistance and the voltage holding ratio of the liquid crystal device obtained in Example 2 of the present invention are considerably high. Therefore, it can be understood that the use of the polymerizable composition containing the compound of the general formula (1) improves the resistance and the voltage holding ratio and also improves the electro-optical characteristics.

(Embodiment 3)

[0056]

Embedded image

A liquid crystal composition (B) was prepared. Various properties of this liquid crystal composition (B) were as follows. Transition temperature 80.1 ℃ (N-I) < -59 ℃ (C-N) refractive index anisotropy _{n e = 1.702 n o = 1.508} Δn = 0.194 dielectric anisotropy [Delta] [epsilon] = 16 .4

In Example 1, the liquid crystal composition (A) 80
%, A liquid crystal device was obtained in the same manner as in Example 1, except that 80% of the liquid crystal composition (B) was used.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device were as follows. V ₁₀ : 4.8 V V ₉₀ : 9.6 V γ: 2.0 Contrast: 1:25 τ _r = τ _d : 10.0 ms Voltage holding ratio: 94% Hysteresis: 0.2 V

Comparative Example 3 Example 3 was repeated except that 19.8% of “KAYARAD-HX620” was used instead of 19.8% of “KU-760” as the polymerizable composition. A liquid crystal device was obtained in the same manner as described above.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed. The characteristics of the obtained liquid crystal device were as follows.

V ₉₀ : 12.7 V Contrast: 1:20 Voltage holding ratio: 82% Hysteresis: 1.0 V

From these results, it is clear that the resistance and the voltage holding ratio of the liquid crystal device obtained in Example 3 of the present invention are considerably high. Therefore, it can be understood that the use of the polymerizable composition containing the compound of the general formula (1) improves the resistance and the voltage holding ratio and also improves the electro-optical characteristics.

Example 4 Instead of using 19.8% of “KU-760” as the polymerizable composition in Example 3, 13.8% of “KU-760” and “LA” 6.
A liquid crystal device was obtained in the same manner as in Example 3, except that 0% was used.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device were as follows. V ₁₀ : 1.9 V V ₉₀ : 3.8 V γ: 2.0 Contrast: 1:29 τ _r = τ _d : 10.0 ms Voltage holding ratio: 94% Hysteresis: 0.1 V

Comparative Example 4 Example 4 was repeated, except that 13.8% of “KAYARAD-HX620” was used instead of 13.8% of “KU-760” as the polymerizable composition. In the same manner as in No. 4, a liquid crystal device was obtained.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device were as follows. V ₉₀ : 7.2 V Contrast: 1:20 Voltage holding ratio: 83% Hysteresis: 1.0 V

From these results, it is clear that the resistance and the voltage holding ratio of the liquid crystal device obtained in Example 4 of the present invention are considerably high. Therefore, it can be understood that the use of the polymerizable composition containing the compound of the general formula (1) improves the resistance and the voltage holding ratio and also improves the electro-optical characteristics.

[0072]

The liquid crystal device of the present invention has a considerably high resistance and voltage holding ratio, is a liquid crystal device of bright image quality, has a large transparent-opaque contrast of about 1:25 or more, and has a threshold capable of time-division driving. This is a light scattering type liquid crystal device having value-voltage characteristics and steepness.

Therefore, the liquid crystal device of the present invention is extremely useful as a display device of a computer terminal and a display element of a projection.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-6525 (JP, A) JP-A-1-313527 (JP, A) JP-A-4-168421 (JP, A) JP-A-4-16821 178619 (JP, A) JP-A-3-192324 (JP, A) JP-A-5-80310 (JP, A) JP-A-3-46620 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1334 C09K 19/54

Claims (7)

(57) [Claims] At least one substrate having an electrode layer has two transparent substrates, and a dimming layer supported between the substrates.
In a liquid crystal device in which the light modulating layer is composed of a transparent solid substance and a liquid crystal material, the transparent solid substance is represented by a general formula (1). (Wherein i, j, k and l each independently represent an integer of 0 to 10.) A transparent solid substance obtained by polymerizing a polymerizable composition containing a bifunctional acrylate represented by the following formula: A liquid crystal device, comprising: 2. The compound represented by the general formula (1) according to claim 1, wherein the transparent solid substance is a compound represented by the general formula (2): (Wherein m, n, p and q each independently represent an integer of 0 to 10.) A transparent solid substance obtained by polymerizing a polymerizable composition containing a bifunctional acrylate represented by the following formula: The liquid crystal device according to claim 1. 3. The compound represented by the general formula (1) according to claim 1, the compound represented by the general formula (2) according to claim 2, and the general formula (3) wherein the transparent solid substance is (Wherein r, s, t and u each independently represent an integer of 0 to 10.) A transparent solid substance obtained by polymerizing a polymerizable composition containing a bifunctional acrylate represented by the following formula: The liquid crystal device according to claim 1. 4. The liquid crystal device according to claim 1, wherein the light modulating layer is a light modulating layer formed by forming a transparent solid substance having a three-dimensional network structure in a continuous layer of a liquid crystal material. 5. The liquid crystal device according to claim 1, wherein a liquid crystal material having a positive dielectric anisotropy is used. 6. The liquid crystal device according to claim 1, wherein a thickness of the light control layer is in a range of 2 to 40 μm. 7. The liquid crystal device according to claim 1, wherein an active element is provided on the transparent electrode layer.