JP3055208B2 - Liquid crystal device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal device having a large area, and more particularly, to blocking, opening, and limiting transmission or blocking of light or illumination light.
It can electrically control the transmission, and is used as a screen for blocking the view of a building window or a show window, or as a curtain for lighting control, and displays characters and figures, with high-speed response. The present invention relates to a method for manufacturing a liquid crystal device used as a display device such as a high information display body such as a display of an OA device or an advertising board, a guide board, a decorative display board or the like by electrically switching its display.

[0002]

2. Description of the Related Art A light modulating layer forming material containing a liquid crystal material, a photopolymerizable composition and a photopolymerization initiator is interposed in a cell having at least one electrode layer formed of two transparent substrates. A method for producing a liquid crystal device having a light modulating layer formed by forming a three-dimensional network structure of a transparent solid substance in a continuous layer of a liquid crystal material by polymerizing the photopolymerizable composition by irradiating ultraviolet rays. Or
In a method for manufacturing a liquid crystal device having a dimming layer in which liquid crystals are dispersed in a polymer in a spherical shape, a peripheral portion of the liquid crystal device excluding the injection hole between the two substrates is sealed, and the injection hole of the cell is formed under vacuum. Immerse in the dimming layer forming material, and recover pressure in that state,
After injecting the dimming layer forming material using a vacuum injection method of injecting into a cell, the dimming layer is formed by irradiating ultraviolet rays, and then a photocurable sealing agent is applied to the injection holes, and further ultraviolet rays are applied. A method of sealing by irradiation has been adopted.

[0003]

However, in the vacuum injection method according to the prior art, a light control layer forming material is injected between the substrates, and the light control layer is formed by irradiating ultraviolet light. Sealing is performed by applying a sealing agent and further irradiating ultraviolet rays. However, this method requires a complicated manufacturing process, and requires two steps for forming a light control layer and sealing.
UV irradiation must be performed twice, which causes a decrease in the resistance value and voltage holding ratio of the liquid crystal device due to the light deterioration of the liquid crystal material, which leads to an increase in power consumption, a shortened life, a screen flicker, and the like. There is a problem that the performance of the liquid crystal device is deteriorated.

An object of the present invention is to provide a method of manufacturing a liquid crystal device by a vacuum injection method in which the deterioration of the liquid crystal device due to the irradiation of ultraviolet rays is suppressed and the manufacturing process is simplified.

[0005]

Means for Solving the Problems The present inventors have made intensive studies on a method of manufacturing a liquid crystal device by a vacuum injection method in which the manufacturing process is simplified, and as a result, have reached the present invention.

That is, in order to solve the above problems, the present invention provides a liquid crystal material, a photopolymerizable composition, and a photopolymerization initiator in a cell having at least one electrode layer formed of two transparent substrates. A method for manufacturing a liquid crystal device having a light modulating layer composed of a liquid crystal material and a transparent solid substance by interposing a light modulating layer forming material contained therein and irradiating ultraviolet light to polymerize the photopolymerizable composition, After sealing the outer peripheral portion except for the injection hole between the two substrates, the light modulating layer forming material is injected, and further, a photocurable sealing agent is injected into the injection hole, and then ultraviolet irradiation is performed. And a method for manufacturing a liquid crystal device.

According to the method of manufacturing a liquid crystal device of the present invention, after injecting a dimming layer forming material, a photocurable sealing agent is injected into the injection hole, and the dimming layer is formed and sealed by a single ultraviolet irradiation. Can be performed at the same time, so that a liquid crystal device in which the number of manufacturing steps is small and light deterioration is suppressed can be manufactured.

In the present invention, when the light modulating layer forming material is vacuum-injected into the cell, it is necessary to inject the material under a condition that is not exposed to ultraviolet rays, for example, by completely shielding the vacuum injection device from light. This is effective for obtaining a liquid crystal device having a uniform light control layer.

As a method of injecting the photocurable sealing agent, a photocurable sealing material is applied in a state in which the light modulating layer forming material is vacuum-injected, and the temperature near the injection hole is further increased.
A method in which this is cooled and sucked and injected into the injection hole. A method in which a light modulating layer forming material is vacuum-injected, a photocurable sealing agent is applied in a state where a constant pressure is applied to the vicinity of the injection hole, and the pressure is returned to normal pressure, whereby suction injection is performed into the injection hole. And the like.

The substrate used in the present invention may be a rigid material, for example, glass, metal, or the like, or a flexible material, for example, a plastic film. Then, two substrates are opposed to each other and are obtained at an appropriate interval. Also, at least one of them is
The light modulating layer, which has transparency and includes a liquid crystal layer and a layer having a transparent solid substance sandwiched between the two, must be visible from the outside. However, complete transparency is not essential. If this liquid crystal device
When used to affect light passing from one side of the device to the other, both substrates are provided with the appropriate transparency. Appropriate transparent and opaque electrodes may be disposed on the entire or partial surface of the substrate depending on the purpose.

In general, a spacer for maintaining a space can be interposed between the two substrates similarly to a known liquid crystal device. The periphery of the substrate except for the injection hole is fixed using a well-known sealing agent.

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 a substance other than the liquid crystal compound. Any material which is generally 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, 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 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. Transition temperature, melting point, viscosity, refractive index anisotropy (Δ
n), for the purpose of improving the dielectric anisotropy (Δε), the solubility with the polymerizable composition, and the like, can be appropriately selected and blended.

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

The content of the liquid crystal material in the light control layer forming material is as follows:
It is preferably at least 60% by weight, particularly preferably from 70 to 90% by weight. The transparent solid substance formed in the light control layer may be a substance in which a liquid crystal material is dispersed in a polymer in a spherical shape, but a substance having a three-dimensional network structure is more preferable.

It is preferable that a liquid crystal material is filled in the three-dimensional network-like portion of the transparent solid substance, and that the liquid crystal material forms a continuous layer. It is indispensable to form a target boundary surface and express light scattering.

As these transparent solid substances, synthetic resins are preferred. As a material giving a three-dimensional network structure, a photocurable resin obtained by polymerizing a polymer-forming monomer or oligomer is preferable.

As a method of forming a three-dimensional network structure by a transparent solid substance formed between substrates, a liquid crystal material in a light modulating layer forming material sealed in a cell is maintained in an isotropic liquid state. While irradiating with ultraviolet rays, a method of polymerizing the photopolymerizable composition may be used.

Examples of the polymer-forming monomer forming 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 or diethylaminoethyl; ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, Mono (meth) acrylate or poly (meth) acryl such as methylolpropane, glycerin and pentaerythritol Rate: vinyl acetate, vinyl butyrate or vinyl benzoate, acrylonitrile, cetyl vinyl ether, limonene, cyclohexene, diallyl phthalate, diallyl isophthalate, 2-, 3- or 4-
Vinylpyridine, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-hydroxymethylacrylamide or N-hydroxyethylmethacrylamide and their alkyl ether compounds; 2 mol or more of ethylene oxide or propylene oxide added to 1 mol of neopentyl glycol Di (meth) acrylate of diol obtained by adding; 3 or more moles of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane; di or tri (meth) acrylate of triol; 2 moles or more per mole of bisphenol A A di (meth) acrylate of a diol obtained by adding ethylene oxide or propylene oxide;
Reaction products of 1 mol of -hydroxyethyl (meth) acrylate with 1 mol of phenyl isocyanate or n-butyl isocyanate; and poly (meth) acrylate of dipentaerythritol.

Examples of the polymer-forming oligomer forming the transparent solid substance include caprolactone-modified hydroxypivalic acid ester neopentyl glycol diacrylate.

Examples of the polymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one (“Darocur 1173” manufactured by Merck) and 1-hydroxycyclohexylphenyl ketone (manufactured by Ciba Geigy) Irgacure 184 ”), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (“ Darocure 1116 ”, manufactured by Merck), benzyldimethylketal (“ Irgacure 65, manufactured by Ciba-Geigy ”)
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.) A mixture of "Kayacure DETX") and ethyl p-dimethylaminobenzoate ("Kayacure-EPA" manufactured by Nippon Kayaku Co., Ltd.), isopropylthioxanthone ("Kantacure ITX" manufactured by Ward Prekinsop)
And mixtures thereof with ethyl p-dimethylaminobenzoate.

Examples of the polymerization inhibitor include hydroquinone monomethyl ether (methquinone), hydroquinone, p-benzoquinone, phenothiazone, mono-t-butylhydroquinone, catechol, pt-butyl catechol, benzoquinone, .5-di-t-butylhydroquinone, anthraquinone, 2.6-di-t-butylhydroxytoluene and the like.

This polymerization inhibitor is generally already added to commercially available photosensitive materials, but the photosensitive composition used in the vacuum injection method is further added with 100 to 5 times.
It is preferable to additionally use it in the range of 00 ppm, and it is possible to increase or decrease as necessary.

The photo-curable sealing agent may be any monomer that can be cured by irradiating ultraviolet rays, and is preferably a compound that is hardly mixed with a liquid crystal material or a compound that has excellent adhesion to a substrate after being cured. And the like are preferred.

[0025]

EXAMPLES Examples of the present invention will be shown below, and the present invention will be described more specifically. However, the invention is not limited to these examples.

In the examples, "%" represents "% by weight". (Example 1) An outer peripheral portion except for an injection hole between two transparent substrates on which ITO electrodes were formed was sealed with a sealant DSA-001 (manufactured by Roddick), and a 10 cm × 10 cm square, cell thickness 1 was used.
An empty cell of 0.0 μm was produced.

Next,

[0028]

Embedded image

A liquid crystal composition (A) was prepared. Various properties of this liquid crystal composition (A) were as follows. 80% of this liquid crystal composition (A), 20% of "Kayarad HX620" (caprolactone-modified hydroxypivalate neopentyl glycol diacrylate manufactured by Nippon Kayaku Co., Ltd.) as a photopolymerizable composition, and "Irgacure 651" as a photopolymerization initiator (Benzyl dimethyl ketal manufactured by Ciba-Geigy Co., Ltd.) A dimming layer forming material consisting of 0.1% was prepared and injected into the empty cell by vacuum injection while keeping at 45 ° C. Next, after applying a photocurable sealing agent “TB3051” (manufactured by Three Bond Co.) near the cell injection hole,
The temperature of the substrate was cooled to 23 ° C., and left as it was for 5 minutes.

The main structure of the liquid crystal device at this time is shown in FIG. In FIG. 1, 1 is a transparent substrate on which a transparent electrode is formed, 2 is a sealant, 3 is a dimming layer forming material,
Is a photocurable sealing agent. FIG. 2 is a sectional view taken along line AA 'of FIG.

Thus, the light control layer forming material and the sealing agent
While maintaining the cell at 23 ° C., 30 mW / cm^Twoof
Irradiation with UV light for 60 seconds completely dimming layer
A liquid crystal device sealed inside was obtained. The liquid crystal at this time
The specific resistance of the device is 6.0 × 10⁹Ω · cm
Was. (Example 2) In the same manner as in Example 1, the light modulating layer forming material was
After vacuum injection, the area near the injection hole is
Pressurize at a constant pressure and apply the same photocurable sealing agent as in Example 1.
Applied. Next, remove the pressurizing jig and release the pressure.
A liquid crystal display that completely seals the dimming layer by
I got a vice. Comparative Example In the same manner as in Example 1, the light modulating layer
After empty injection, 30mW / cm^TwoUV light for 60 seconds
Thus, a liquid crystal device having a light control layer was obtained. Then, light hard
Injection of “TB3051” (a product of Three Bond Co., Ltd.)
Apply to the entrance hole, again 30mW / cm ^TwoUV light for 60 seconds
Fired.

At this time, the specific resistance of the liquid crystal device is 3.
The resistivity was 0 × 10 ⁸ Ω · cm, and the specific resistance was lower than that of Example 1 due to light deterioration.

[0033]

According to the method for manufacturing a liquid crystal device of the present invention, it is possible to provide a liquid crystal device having a small number of manufacturing steps and suppressing the deterioration of the specific resistance value due to light.

Therefore, it is possible to efficiently manufacture 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.

[Brief description of the drawings]

FIG. 1 is a plan view of a liquid crystal device before ultraviolet irradiation according to the present invention.

FIG. 2 is a sectional view taken along the line AA 'of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Sealing agent 3 Light control layer forming material 4 Photocurable sealing agent

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-4216 (JP, A) JP-A-63-81324 (JP, A) JP-A-3-91718 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) G02F 1/1334 G02F 1/1339 505 G02F 1/1341

Claims (2)

(57) [Claims] 1. A light modulating layer forming material containing a liquid crystal material, a photopolymerizable composition and a photopolymerization initiator is interposed in a cell having at least one electrode layer formed of two transparent substrates. Irradiating ultraviolet rays to polymerize the photopolymerizable composition, thereby producing a liquid crystal device having a light modulating layer composed of a liquid crystal material and a transparent solid substance, excluding an injection hole between the two substrates. After sealing the outer peripheral part, the light modulating layer forming material is vacuum- injected, and further (1)
After applying a photocurable sealing agent to the injection hole while the area around the inlet is heated, the sealing agent is injected by cooling the substrate.
After injection into the hole, or (2) constant near the injection hole
Photocurable sealant was applied to the injection hole under pressure
After returning to normal pressure, the sealing agent is injected into the injection hole
And then performing ultraviolet irradiation. 2. The method for manufacturing a liquid crystal device according to claim 1, wherein the light modulating layer has a transparent solid substance formed by forming a three-dimensional network structure in a continuous layer of the liquid crystal material.