JP3318547B2 - Method for manufacturing liquid crystal electro-optical 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 electro-optical device which can be easily expanded to a large area, and a liquid crystal electro-optical device according to the present invention. It is conceivable to apply the daylighting control to a curtain or to a liquid crystal display device that displays characters, figures, symbols, and the like and electrically rewrites them.

[0002]

2. Description of the Related Art As a conventional liquid crystal display device, a TN type or STN type using a nematic liquid crystal has been widely put into practical use. Recently, a device using a ferroelectric liquid crystal has been known. Each of these devices requires a polarizing plate, and it is necessary to regularly align the liquid crystal in a certain direction in the device. On the other hand, without the need for these polarizing plates and orientation,
Dispersion type liquid crystals having a bright screen and good contrast are known. This dispersion type liquid crystal is a liquid crystal in which a light-transmitting solid-state polymer holds nematic, cholesteric, or smectic liquid crystals in a granular or spongy state. As a method of manufacturing this liquid crystal device, a method is known in which liquid crystal is dispersed in a polymer by encapsulating the liquid crystal, and the polymer is formed as a thin film on a film or a substrate. Here, gelatin, gum arabic, polyvinyl alcohol and the like have been proposed as encapsulating substances.

In these techniques, liquid crystal molecules encapsulated in polyvinyl alcohol are aligned in the direction of the electric field in the presence of an electric field if they have a positive dielectric anisotropy in a thin film. However, when the refractive index of the liquid crystal is equal to the refractive index of the polymer, transparency is exhibited. On the other hand, when there is no electric field, the liquid crystal is oriented in various directions without being arranged in a specific direction, so the refractive index of the liquid crystal is shifted from the refractive index of the polymer, the light is scattered and the transmission of the light is blocked, It becomes cloudy. In addition to the above-described examples, there are some known polymers and thin films in which the encapsulated liquid crystal is dispersed to have a polymer therein. For example, those in which a liquid crystal material is dispersed in an epoxy resin, those using phase separation between a liquid crystal and a photocurable substance, those in which a liquid crystal is impregnated in a three-dimensionally connected polymer, and the like are known. . In the present invention, these liquid crystal electro-optical devices are collectively called dispersion type liquid crystal.

[0004]

In the practical use of the large-sized liquid crystal electro-optical device as described above, especially in the method of manufacturing the liquid crystal electro-optical device, a technique for manufacturing a large-sized device at low cost is required. ing.

[0005] The problem with increasing the size is that the liquid crystal injection technique used in a general liquid crystal manufacturing process cannot be used because the viscosity of the transparent solid used for the dispersion type liquid crystal is extremely high. For this reason, a thin film is formed on one substrate by a coating method, a casting method, or the like, and then the other substrate is fixed by overlapping.

In addition, when the size is increased, it is necessary to uniformly disperse the spacers in order to keep the distance between the pair of substrates constant. However, in the case of the dispersion type liquid crystal, the coating method and the casting method are used for the reasons described above. In this process,
Uniformly dispersed spacers are deviated or partially aggregated and are not uniformly distributed, resulting in a liquid crystal electro-optical device having uneven substrate spacing.

[0007]

SUMMARY OF THE INVENTION The present invention proposes a method for solving the above-mentioned problems and realizing a large-sized dispersion-type liquid crystal electro-optical device which is cheaper and easier to manufacture.

That is, a method of manufacturing an electro-optical device of a dispersion type liquid crystal having a pair of substrates having electrode layers and having at least one of them transmitting light and a light modulating layer containing a transparent solid substance and a liquid crystal material between the pair of substrates. A step of dispersing spacers on the electrode side of one of the pair of substrates; a step of fixing the spacer on the electrode side of the substrate; and the light modulating layer after the step. Forming a;
Fixing the spacers to the substrates, fixing the spacers to the substrates, forming a dimming layer, uniformly distributing the spacers, and disposing the liquid crystal electrodes at uniform substrate intervals. It realizes an optical device.

In addition, the light-transmitting solid phase polymer and the liquid crystal material are not dissolved in a common solvent when the light modulating layer is formed, and the liquid crystal material is mixed with the light transmitting solid phase polymer. After applying the pressure on the substrate with the spacer fixed on it and overlaying the other substrate on a predetermined position, applying pressure and setting it at a predetermined interval, light irradiation, heating, or both are performed to fix the substrate It is.

Here, the light control layer includes a transparent solid substance (a transparent solid polymer or a polymer-forming monomer) and a nematic, cholesteric or smectic liquid crystal. Is what is being held. This translucent solid polymer is used alone or as a mixture of polyethylene, polymethacrylate, polystyrene, polyvinyl chloride, polyacrylonitrile, polyvinyl alcohol, polyester, polyamide resin, polyethylene terephthalate resin, fluororesin, silicone resin and the like. Can be

As the light modulating layer constituting material, a polymer-forming monomer and a liquid crystal material or a mixture of the solid phase polymer and the liquid crystal material dissolved in a common solvent is used. In the former case, the mixture is applied onto a substrate by a coating method and then irradiated with heat or light to form a light control layer. On the other hand, the latter applies a dissolved liquid material to form a liquid medium layer, and then removes the solvent to form a light control layer.

As the solvent, ketones, alcohols,
Unsaturated hydrocarbons such as benzene and toluene and water can be used. These are appropriately selected depending on the method of application, and used alone or in combination.

The method of application may be a method such as doctor knife, roll coater, curtain coater, knife coater, spray coating, spin coating, screen printing, offset printing, etc., depending on the shape and characteristics of the liquid crystal material.

[0014]

[Embodiment 1] FIG. 1 shows a process chart of a method of manufacturing a liquid crystal electro-optical device of this embodiment. As a substrate to be used, a 2000-mm-thick IT
O having a predetermined pattern was used. Spacers 4 having an average particle diameter of 10.5 μm were sprayed on the electrode side of the substrate by a wet method. This spacer is a composite of an inner hard sphere portion and an organic material on the outer surface, and is dispersed in a mixed solvent of methyl alcohol and Freon. In the dispersed state shown in FIG. 1A, a heat treatment at 150 to 200 ° C. (180 ° C. in the present embodiment) is performed for about 15 minutes, and simultaneously with the removal of the solvent, the organic matter on the outer surface of the spacer is melted to remove the substrate surface. And adhered and fixed.

Next, a mixed aqueous solution of polyvinyl alcohol and a nematic liquid crystal is applied by a spin coater, and then heat-treated at 120 ° C. for 20 minutes to obtain a light control with a thickness of about 10 to 12 μm as shown in FIG. Layer 5 was formed. Next, the other substrate 2 is stacked at a predetermined position, and while being pressed under a pressure of 1 to 5 kg / cm ² , a heat treatment is performed at 120 ° C. for 30 minutes to fix the pair of substrates, and FIG. Thus, a liquid crystal electro-optical device was completed.

The uniformity of the substrate spacing of the manufactured device is 2
It was within 10.2 μm ± 0.1 for a 00 mm × 260 mm substrate, and the spacers were also appropriately dispersed in the substrate without being biased by spin coating at the time of producing the light control layer.

The bonding with the other substrate may be performed under a vacuum or reduced pressure atmosphere as necessary.
In that case, the step of removing the solvent after the spin coating can be omitted.

[0018]

[Embodiment 2] This embodiment is also described with reference to a process chart of a manufacturing method as shown in FIG. As a substrate to be used, a transparent electrode having a thickness of 2000
The one obtained by forming ITO3 of Å into a predetermined pattern was used. Spacers 4 having an average particle size of 10.5 μm were sprayed on the electrode surface of the substrate by a wet method. This spacer is a composite of an inner hard sphere portion and an organic material on the outer surface, and is dispersed in a mixed solvent of methyl alcohol and Freon. In the state of FIG.
About 200 ° C. (180 ° C. in this embodiment)
After 5 minutes, the solvent was removed, and at the same time, the organic matter on the outer surface of the spacer was melted and adhered and fixed to the substrate surface.

Next, a mixed homogeneous solution of the prepolymer and the nematic liquid crystal was formed to a thickness of about 15 μm by a screen printing method. As this prepolymer, a uniform solution was used in which trimethylolpropane triacrylate was mixed with a polymerization initiator at a ratio of about 25% to a normal nematic liquid crystal material. Next, the other substrate is placed on a predetermined position, and is pressed by applying a pressure of 1 to 5 kg / cm ^{2 so} as to have a thickness of about 10 μm, and an unnecessary uniform solution between the substrates is removed. And extruded. The unnecessary uniform solution was wiped, and the entire surface of the substrate was irradiated with ultraviolet light to cure (polymerize) the monomer formed between the substrates, thereby fixing the pair of substrates. The irradiation conditions were as follows: a substrate was placed at a distance of about 20 cm from an ultraviolet lamp of 100 W / cm, and irradiation was performed for about 5 minutes. In this way, the dimming layer 5 containing the transparent solid substance and the liquid crystal was formed, and at the same time, both substrates were fixed to complete the liquid crystal electro-optical device as shown in FIG.

The uniformity of the substrate spacing of the manufactured device is 2
10.0 μm ± 0.1 for a 00 mm × 260 mm substrate,
The spacers between the substrates were also appropriately dispersed in the substrates without being biased by screen printing at the time of producing the light control layer.

In the case of the present embodiment, there is no need to remove the solvent after the application of the light control layer, and it is very effective in increasing the area. Furthermore, it was effective to increase the degree of adhesion of the substrate by applying a heat treatment during or after the polymerization of the monomer.

[0022]

[Embodiment 3] This embodiment is also described with reference to a process chart of a manufacturing method as shown in FIG. As a substrate to be used, a transparent electrode 3 having a thickness of 200
The one in which ITO of 0 ° was formed in a predetermined pattern was used. Spacers 4 having an average particle diameter of 10.5 μm were sprayed on the electrode side of the substrate by a wet method. This spacer is a composite of an inner hard sphere portion and an organic material on the outer surface, and is dispersed in a mixed solvent of methyl alcohol and Freon. In the state of FIG.
About 200 ° C. (180 ° C. in this embodiment)
After 5 minutes, the solvent was removed, and at the same time, the organic matter on the outer surface of the spacer was melted and adhered and fixed to the substrate surface.

Next, a mixed homogeneous solution of the prepolymer and the nematic liquid crystal was formed to a thickness of about 15 μm by a screen printing method. As this prepolymer, a uniform solution was used in which trimethylolpropane triacrylate was mixed with a polymerization initiator at a ratio of about 25% to a normal nematic liquid crystal material. Next, the other substrate is placed on a predetermined position, and is pressed by applying a pressure of 1 to 5 kg / cm2 so as to have a thickness of about 10 μm. Extruded. Next, a portion other than the overlapping portion of the pair of substrates is masked so as not to be irradiated with light, and the substrate is irradiated with ultraviolet light to cure (polymerize) the monomer, and the transparent solid substance and the liquid crystal are separated. A light modulating layer including the substrate was formed, and a pair of substrates was fixed. The irradiation conditions were as follows: a UV lamp of 100 W / cm was placed at a distance of about 20 cm, the substrate was placed, and irradiation was performed for about 5 minutes. Thereafter, the peripheral portion that is not irradiated with ultraviolet light is washed with an organic solvent, the mixed homogeneous solution protruding from the substrate is removed, and the substrate is fixed, and the liquid crystal electro-optical device is completed as shown in FIG. did.

In the case of this embodiment, when removing the mixed homogeneous solution protruding from the substrate, the electrode take-out portion of the substrate can be washed at the same time. Was also improved.

In the above embodiment, other coating methods can be used as needed for coating the light control layer. In that case, it can be appropriately selected according to the components, viscosity and characteristics of the solution to be used.

Although a spacer is a composite spacer, a photosensitive organic material is formed on the entire surface of the substrate, and then a predetermined mask is used to irradiate only a required portion with light, and after development, the organic material is left at an arbitrary position. May be provided with a spacer.

[0027]

According to the structure of the present invention, it is possible to manufacture a large-sized dispersion-type liquid crystal electro-optical device having a uniform spacing between substrates with a small number of steps and inexpensively, without biasing the spacers. In addition, since the spacers are not biased, uniform display can be performed without display unevenness.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a liquid crystal electro-optical device of an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Substrate 3 Electrode 4 Spacer 5 Light control layer

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-165622 (JP, A) JP-A-1-303414 (JP, A) JP-A-64-55519 (JP, A) JP-A-63-165 94224 (JP, A) JP-A-63-172123 (JP, A) JP-A-63-311233 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1339 G02F 1 / 13 101 G02F 1/1334

Claims (4)

(57) [Claims] A step of forming a transparent electrode on each of a first substrate and a second substrate; and a step of forming a hard sphere on the transparent electrode of the first substrate and
A step of spraying a spacer comprising an organic substance formed on the outer surface of the portion, and spraying the spacer on the transparent electrode of the first substrate
After that, the organic matter is melted by heat treatment,
Is exposed, and the molten portion of the organic material and the first
A step of bonding and fixing the transparent electrode of the substrate, a step of applying a light control layer containing a liquid crystal and a precursor of the polymer to the transparent electrode of the first substrate, With the transparent electrode of the second substrate facing the first substrate and the second substrate,
When bonding while applying pressure, the second
Deform the contact part of the substrate of the above hard sphere surface part
Are exposed, forming a gap, the ultraviolet light was irradiated on the first substrate and the second light control layer formed between the substrate, by curing the precursor of the polymer, And a step of maintaining a gap . 2. A step of forming a transparent electrode on each of a first substrate and a second substrate; and a step of forming a hard sphere on the transparent electrode of the first substrate ,
A step of spraying a spacer comprising an organic substance formed on the outer surface of the portion, and spraying the spacer on the transparent electrode of the first substrate
After that, the organic matter is melted by heat treatment,
Is exposed, and the molten portion of the organic material and the first
A step of bonding and fixing the transparent electrode of the substrate, a step of applying a light control layer containing a liquid crystal and a precursor of the polymer to the transparent electrode of the first substrate, With the transparent electrode of the second substrate facing the first substrate and the second substrate,
When bonding while applying pressure, the second
The contact portion of the substrate is deformed, and the portion of the hard sphere surface is deformed.
Min is exposed and forming a gap, said first substrate or when viewed from a normal direction of the second substrate, masks the outside of the outer or the second substrate of said first substrate , ultraviolet light was irradiated on the light control layer, wherein the poly
The first substrate and the second
Bonding a substrate to maintain a gap . 3. The method of claim 1 or claim 2, wherein the liquid crystal, a method for manufacturing a liquid crystal electro-optical device according to claim it is a nematic liquid crystal. 4. A any one of claims 1 to 3, wherein the step of coating, doctor knife, roll coater, curtain coater, knife coater, spray coating, spin coating, screen printing, either in offset printing A method for manufacturing a liquid crystal electro-optical device.