JPH05188358A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal device which maintains the accuracy of an inter-substrate spacing and can improve scattering characteristics by interposing spacers contg. porous particles between two sheets of substrates. CONSTITUTION:This liquid crystal device has two sheets of the substrates which have electrode layers and at least one of which are transparent and the light control layer which is supported between these substrates. The light control layer is constituted of a liquid crystal material and a transparent solid material. The spacers contg. the porous particles are provided between two sheets of the substrates in such a case. The light control layer preferably contains the transparent solid material forming a three-dimensional network structure in the continuous layer of the liquid crystal material. The spacers are required to have no reactivity and solubility with the liquid crystal material and to be chemically stable. Further, the porous particles are exemplified by inorg. porous particles of a silica gel, molecular sieve, alumina, etc., and porous polymer beads, etc., essentially consisting of a copolymer of styrene and divinyl benzene, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal device capable of forming a large area, and more particularly, to blocking or opening a field of view and limiting or blocking transmission of light or illumination light.
The transmission can be electrically operated, and it is used as a screen for blocking the field of view in building windows and show windows, and as a curtain for daylighting control. The present invention relates to a method of manufacturing a liquid crystal device used as a display device such as a high information display body such as a display of an office automation equipment, an advertising board, a guide board, a decorative display board, etc. by electrically switching the display.

[0002]

2. Description of the Related Art A dimming layer is provided between two transparent substrates, at least one of which has an electrode layer, and the dimming layer comprises a liquid crystal material and a transparent solid substance. In a liquid crystal device, which is a light control layer dispersed in the form of liquid droplets, glass beads, rod-shaped glass fibers, alumina particles, between the two substrates in order to maintain the space between the two substrates. Spacers such as glass powder, silica particles, alumina particles and various polymer beads were interposed.

[0003]

However, conventional spacers are non-porous particles having transparency, and in the case of a liquid crystal device having a large substrate, in order to improve the accuracy of the substrate spacing, the spacer dispersion density should be increased. Therefore, the scattering characteristics of the liquid crystal device are deteriorated, which is a practical problem.

The problem to be solved by the present invention is to provide a liquid crystal device which can maintain the accuracy of the substrate spacing and improve the scattering characteristics.

[0005]

The present inventors have arrived at the present invention as a result of intensive research on a liquid crystal device capable of maintaining the accuracy of the substrate spacing and improving the scattering characteristics.

In other words, in order to solve the above-mentioned problems, the present invention provides a liquid crystal device having a dimming layer composed of a liquid crystal material and a transparent solid substance between two substrates having at least one transparent electrode layer. Provided is a liquid crystal device having a spacer containing porous particles between the two substrates.

In the liquid crystal device of the present invention, since the spacer containing the porous particles is used, it is clear that the light-scattering property is improved as compared with the case where the conventional spacer containing only non-porous particles is used. is there.

The spacer used in the present invention is a spacer containing porous particles, and it is preferable that the porous particles have a pore size in the range of 0.4 to 2.0 μm. Any material may be used as long as it has a strength capable of maintaining the accuracy of the distance between the substrates due to the scattering of the light.

The spacer used in the present invention must be chemically stable without any reaction or solubility with the liquid crystal material. As such porous particles,
Examples thereof include inorganic porous particles such as silica gel, molecular sieve, and alumina, and porous polymer beads whose main component is a styrene-divinylbenzene copolymer.

The substrate used in the present invention may be a rigid material such as glass or metal, or a flexible material such as a plastic film. The two substrates are opposed to each other and are separated by an appropriate distance. Also, at least one of them
The light control layer having transparency and a liquid crystal layer sandwiched between the two and a layer having a transparent solid substance should be visible from the outside world. However, 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, the two substrates are both provided with suitable transparency. . Appropriate transparent or opaque electrodes may be disposed on the entire surface or a part of the substrate, depending on the purpose.

Further, the peripheral portions of the two substrates excluding the injection holes are fixed by using a well-known sealant.

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 compounds. What is normally recognized as a liquid crystal material in this technical field may be used, and one having a positive dielectric anisotropy is preferable. 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 the performance, a cholesteric liquid crystal, a chiral nematic liquid crystal, a 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 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. Transition temperature, melting point, viscosity, refractive index anisotropy (Δ
n), dielectric anisotropy (Δε), solubility with a polymerizable composition and the like can be appropriately selected and blended for use.

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 pyrimidines, and among these compounds, compounds having a cyano group at least at one end of the molecule are particularly preferable.

The content of the liquid crystal material in the light control layer forming material is
It is preferably 60% by weight or more, particularly preferably 70 to 90% by weight.

The transparent solid substance formed in the light control layer may be one in which a liquid crystal material is dispersed in the form of liquid drops in a polymer, but one having a three-dimensional network structure is more preferable.

It is preferable that the three-dimensional mesh portion of the transparent solid substance is filled with a liquid crystal material, and the liquid crystal material forms a continuous layer. By forming a disordered state of the liquid crystal material, It is indispensable for forming the optical boundary surface and expressing the scattering of light.

Synthetic resins are suitable as these transparent solid substances. A photo-curable resin obtained by polymerizing a polymer-forming monomer or oligomer is preferable as a material that gives a three-dimensional network structure.

As a method of forming a three-dimensional network structure by a transparent solid substance formed between substrates, a light control layer forming material sandwiched between two substrates is kept in an isotropic liquid state. However, a method of irradiating ultraviolet rays to polymerize the photopolymerizable composition can be mentioned.

Examples of the polymer-forming monomer that forms the transparent solid substance include styrene, chlorostyrene,
α-methylstyrene, divinylbenzene: As a substituent, methyl, ethyl, propyl, butyl, amyl, 2-
Ethylhexyl, octyl, nonyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, allyl, methallyl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-chloro-2-hydroxypropyl, Acrylate, methacrylate or fumarate having a group such as dimethylaminoethyl, diethylaminoethyl, etc .; ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, tri Mono (meth) acrylates such as methylolpropane, glycerin and pentaerythritol, or poly (meth) a Relate; vinyl acetate, vinyl butyrate or vinyl benzoate, acrylonitrile, cetyl vinyl ether, limonene, cyclohexene, diallyl phthalate, diallyl isophthalate, 2-, 3- or 4
-Vinyl pyridine, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-hydroxymethyl acrylamide or N-hydroxyethyl methacrylamide and their alkyl ether compounds; 2 mol or more of ethylene oxide or propylene oxide per 1 mol of neopentyl glycol. Di (meth) acrylate of diol obtained by addition; Di or tri (meth) acrylate of triol obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane; 2 moles per 1 mole of bisphenol A. Di (meth) acrylate of diol obtained by adding the above ethylene oxide or propylene oxide; 1 mol of 2-hydroxyethyl (meth) acrylate and phenylisocyanate Reaction products of bets or n- butyl isocyanate 1 mol, dipentaerythritol poly (meth) acrylate, and the like.

As the polymer-forming oligomer forming the transparent solid substance, for example, epoxy (meth) acrylate, polyester (meth) acrylate, polyurethane (meth) acrylate, polyether (meth) acrylate, etc. may be used. it can.

Examples of the polymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one ("Darocur 1173" manufactured by Merck & Co., Inc.), 1-hydroxycyclohexyl phenyl ketone ("Ciba Geigy Co."). Irgacure 184 "), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (Merck" Darocur 1116 "), benzyl dimethyl ketal (Ciba Geigy" Irgacure 65 "
1 "), 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1 (" Irgacure 907 "manufactured by Ciba Geigy), 2,4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd.) "Kayacure DETX") and ethyl p-dimethylaminobenzoate ("Kayacure-EPA" manufactured by Nippon Kayaku Co., Ltd.), isopropyl thioxanthone ("Kantacure IT" manufactured by Ward Prekinsop)
X ") and a mixture of ethyl p-dimethylaminobenzoate and the like.

[0024]

EXAMPLES The present invention will be described in more detail below by showing Examples of the present invention. However, the invention is not limited to these examples.

In the following examples, "%" represents "% by weight", and each of the evaluation characteristics means the following symbols and contents.

T ₀ : White turbidity; Light transmittance (%) when applied voltage is 0 T ₁₀₀ : Transparency; Light transmittance (%) when the applied voltage is increased and the light transmittance hardly increases V ₉₀ : saturation voltage; same as above, applied voltage (V _rms ) at which light transmittance becomes 90% CR: contrast = T ₁₀₀ / T ₀

(Example 1) "Micropearl SP210" (polymer beads manufactured by Sekisui Fine Chemical Co., Ltd .; particle size: 10 microns) and porous as non-porous particles on one of two transparent substrates having ITO electrodes formed thereon. Spacer in which "WAKOGEL LC-10K" (silica gel manufactured by Wako Pure Chemical Industries; particle size 10 micron) was mixed at a weight ratio of 1: 2 as the functional particles, and the peripheral portion of the substrate other than the injection hole portion of the other substrate was dispersed. , "DSA-001" as sealing agent
(Manufactured by Rodick Co., Ltd.) was applied, and this substrate and the substrate on which the above-mentioned spacers were dispersed were bonded to each other, and the sealant was baked and cured to form an empty cell of 10 cm × 10 cm square and a cell thickness of 10 μm.

Next, as a liquid crystal composition, "PN-001"
(Rodick) 82%, photopolymerizable composition "Kayarad HX620" (Nippon Kayaku Co., Ltd. caprolactone modified hydroxypivalate neopentyl glycol diacrylate) 17.8%, and photopolymerization initiator "Irgacure 651" A dimming layer forming material consisting of 0.2% of benzyl dimethyl ketal (manufactured by Ciba Geigy) was prepared and injected into the above empty cell by the vacuum injection method while maintaining the temperature at 45 ° C.

While keeping the cell into which the material for forming a light control layer was injected at 40 ° C., an ultraviolet ray of 30 mW / cm ² was applied to the cell.
Irradiation was performed for 0 seconds to obtain a cloudy liquid crystal device. 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.

When the relationship between the applied voltage and the light transmittance of this liquid crystal device was measured, it was as follows.

T ₀ = 2.8%, T ₁₀₀ = 86.5%, CR = 30.9, V ₉₀ = 12.3V _rms

(Comparative Example) In Example 1, "Micropearl SP21" was used without using porous particles as spacers.
A white turbid liquid crystal device was obtained in the same manner as in Example 1 except that the total amount of "0" was used as a spacer.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a three-dimensional mesh-like transparent solid substance could be confirmed. When the relationship between the applied voltage and the light transmittance of this liquid crystal device was measured, it was as follows.

T ₀ = 3.9%, T ₁₀₀ = 87.6%, CR = 22.4, V ₉₀ = 13.1V _rms

As described above, it is clear that the liquid crystal device of the present invention is a liquid crystal device having a large white turbidity, an excellent light scattering property and a high contrast as compared with the liquid crystal device of the comparative example.

[0036]

Since the liquid crystal device of the present invention uses the spacer containing the porous particles, it is possible to improve the white turbidity and to provide the liquid crystal device with improved contrast as compared with the conventional one.

Therefore, it can be used for a liquid crystal device used for a screen for blocking a visual field, a curtain for adjusting lighting, a computer terminal, a projection and the like.

Claims (2)

[Claims] 1. A liquid crystal device having two transparent substrates, at least one of which has an electrode layer, and a light control layer supported between the substrates, the light control layer comprising a liquid crystal material and a transparent solid substance. A liquid crystal device having a spacer containing porous particles between the two substrates. 2. The liquid crystal device according to claim 1, wherein the light control layer has a transparent solid substance formed by forming a three-dimensional network structure in a continuous layer of the liquid crystal material.