JPH04216528A - Production of liquid crystal electro-optical device - Google Patents

Abstract

PURPOSE:To offer a method to manufacture a dispersion type liquid crystal electro-optical device which can be easily extended into a large area so as to have uniform distance between substrates at low cost. CONSTITUTION:The liquid crystal electro-optical device consists of a pair of substrates having electrode layers and at least one of which transmits light, a dimming layer containing transparent solid material and liquid crystal material provided between these substrates. The method of manufacturing the device consists of a process to disperse and dispose spacers 4 on the electrode surface of one of the substrates 1, 2, a process to fix the spacers 4 on the electrode surface of the substrate, a process to form a dimming layer 5, and a process to stick the one pair of substrates 1, 2, at specified position and to fix them by heating or irradiation of light.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a liquid crystal electro-optical device that can be easily expanded to a large area. Possible applications include curtains for lighting control and liquid crystal display devices that display characters, figures, symbols, etc. and electrically rewrite them.

0002

2. Description of the Related Art As conventional liquid crystal display devices, TN type and STN type devices using nematic liquid crystal have been widely put into practical use. Also, recently, devices using ferroelectric liquid crystals are known. All of these devices require polarizing plates, and it is necessary to orient the liquid crystal regularly in a certain direction within the device. On the other hand, these do not require polarizing plates or orientation,
Dispersed liquid crystal displays with bright screens and good contrast are known. This dispersed liquid crystal is one in which a translucent solid phase polymer holds nematic, cholesteric, or smectic liquid crystal in a granular or spongy form. A known method for producing this liquid crystal device is to disperse the liquid crystal in a polymer by encapsulating the liquid crystal, and then to form the polymer as a thin film on a film or a substrate. Here, gelatin, gum arabic, polyvinyl alcohol, etc. have been proposed as the encapsulating material.

In these techniques, liquid crystal molecules encapsulated in polyvinyl alcohol can be aligned in the direction of the electric field in the presence of an electric field if they have positive dielectric anisotropy in the thin film. However, when the refractive index of the liquid crystal and the refractive index of the polymer are equal, transparency is exhibited. On the other hand, in the absence of an electric field, the liquid crystals are not aligned in a specific direction but are oriented in various directions, so the refractive index of the liquid crystal differs from the refractive index of the polymer, causing light to be scattered and blocking light transmission. It becomes cloudy. In addition to the above-mentioned examples, several other types of polymer films or thin films containing dispersed encapsulated liquid crystals are known. For example, methods in which liquid crystal material is dispersed in epoxy resin, methods that utilize phase separation between liquid crystal and photocuring material, and methods in which liquid crystal is impregnated into three-dimensionally connected polymers are known. . In the present invention, these liquid crystal electro-optical devices are collectively referred to as a dispersed liquid crystal.

0004

[Problems to be Solved by the Invention] In the practical application of large-sized liquid crystal electro-optical devices as described above, there is a need for a technique for easily manufacturing large-sized devices at low cost, especially in the method of manufacturing liquid crystal electro-optical devices. ing.

[0005] A problem with increasing the size is that the viscosity of the transparent solid material used in this dispersed liquid crystal is extremely high, making it impossible to use the liquid crystal injection technique used in general liquid crystal manufacturing processes. Therefore, after forming a thin film on one substrate by a coating method, a casting method, etc., the other substrate is stacked and fixed.

Furthermore, when increasing the size, it is necessary to uniformly disperse spacers in order to maintain a constant distance between a pair of substrates, but in the case of dispersed liquid crystals, coating and casting methods are used for the reasons mentioned above. In this process,
The spacers, which had been uniformly dispersed, became uneven or partially aggregated and were not evenly distributed, resulting in a liquid crystal electro-optical device with uneven substrate spacing.

[0007]

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

That is, a method for manufacturing a dispersed liquid crystal electro-optical device having a pair of substrates having an electrode layer, at least one of which is transparent, and a light control layer containing a transparent solid substance and a liquid crystal material between the pair of substrates. A step of dispersing spacers on the electrode surface side of one of the pair of substrates, a step of fixing the spacers on the electrode surface side of the substrate, and a step of disposing the light control layer after the step. and a step of gluing and fixing the pair of substrates in a predetermined positional relationship, thereby fixing the spacers to the substrates, forming a light control layer, uniformly distributing the spacers, and fixing the pair of substrates in a predetermined positional relationship. This realizes a liquid crystal electro-optical device with a uniform substrate spacing.

[0009] Furthermore, when forming the light control layer, the light-transmitting solid-phase polymer and the liquid crystal material are not dissolved in a common solvent, but a state in which the substance that becomes the light-transmitting solid-phase polymer and the liquid crystal material are mixed is used. It is applied onto a substrate with a spacer fixed on it, the other substrate is placed in a predetermined position, pressure is applied to create a predetermined spacing, and the substrate is fixed by light irradiation, heating, or both. It is.

[0010] Here, the light control layer includes a transparent solid material (a translucent solid phase polymer or a polymer-forming monomer) and a nematic, cholesteric or smectic liquid crystal, and these liquid crystals have a granular or spongy shape. This is what is being retained. This translucent solid-phase polymer may be polyethylene, polymethacrylic acid ester, polystyrene, polyvinyl chloride, polyacrylonitrile, polyvinyl alcohol, polyester, polyamide resin, polyethylene terephthalate resin, fluororesin, silicone resin, etc. alone or in combination. It will be done.

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

[0012] As the solvent, ketones, alcohols,
Unsaturated hydrocarbons such as benzene and toluene, water, etc. can be used. These are appropriately selected depending on the coating method and used alone or in combination.

[0013] Depending on the shape and characteristics of the liquid crystal material, the coating method may be a doctor knife, roll coater, curtain coater, knife coater, spray coating, spin coating, screen printing, offset printing, or the like.

[0014]

Embodiment 1 FIG. 1 shows a process diagram of a method for manufacturing a liquid crystal electro-optical device according to this embodiment. The substrate used is an IT film with a thickness of 2000 Å as a translucent electrode 3 on a normal blue plate glass 1.
A material in which O was formed into a predetermined pattern was used. Spacers 4 having an average particle size of 10.5 μm were sprinkled on the electrode surface side of this substrate by a wet method. This spacer is a composite of an internal hard spherical part and an organic substance on the external surface, and is dispersed in a mixed solvent of methyl alcohol and chlorofluorocarbon. Heat treatment at 150 to 200°C (180°C in this example) is performed for about 15 minutes in the dispersed state shown in FIG. It was glued and fixed.

[0015] Next, a mixed aqueous solution of polyvinyl alcohol and nematic liquid crystal was applied using a spin coater, followed by heat treatment at 120°C for 20 minutes to form a dimming film with a thickness of approximately 10 to 12 μm as shown in Figure 1(B). Layer 5 was formed. Next, the other substrate 2 is stacked in a predetermined position, and while being pressed with a pressure of 1 to 5 kg/cm2, heat treatment is performed at 120°C for 30 minutes to fix the pair of substrates, as shown in FIG. 1(C). A liquid crystal electro-optical device was completed.

The uniformity of the substrate spacing in this fabricated device is 2.
It was within 10.2 μm±0.1 for a 00 mm x 260 mm substrate, and the spacers were not biased during spin coating during the production of the light control layer and were appropriately dispersed within the substrate.

[0017] Furthermore, the bonding with the other substrate may be carried out in a vacuum or reduced pressure atmosphere, if necessary.
In that case, it is possible to omit the step of removing the solvent after spin coating.

[0018]

[Embodiment 2] This embodiment will also be explained using process diagrams of the manufacturing method as shown in FIG. The substrate used is an ordinary blue plate glass 1 with a thickness of 2000 mm as a translucent electrode.
ITO3 having a thickness of 1.5 Å formed into a predetermined pattern was used. Spacers 4 having an average particle size of 10.5 μm were sprinkled on the electrode surface of this substrate by a wet method. This spacer is a composite of an internal hard spherical part and an organic substance on the external surface, and is dispersed in a mixed solvent of methyl alcohol and chlorofluorocarbon. In this dispersed state of FIG. 1 (A), 150~
Heat treatment at 200°C (180°C in this example) was performed for about 15 minutes.
At the same time as the solvent was removed, the organic matter on the outer surface of the spacer was dissolved, and the spacer was bonded and fixed to the substrate surface.

Next, a uniform mixed solution of prepolymer and nematic liquid crystal was formed to a thickness of about 15 μm by screen printing. Trimethylolpropane triacrylate was used as the prepolymer, and a homogeneous solution was used in which it was mixed with a polymerization initiator at a ratio of about 25% to a normal nematic liquid crystal material. Next, stack the other substrate in a predetermined position and press it with a pressure of 1 to 5 kg/cm2 so that the thickness becomes about 10 μm, and remove the unnecessary uniform solution between the substrates. I pushed it out. This unnecessary uniform solution was wiped off, and the entire surface of the substrates was irradiated with ultraviolet light to harden (polymerize) the monomer formed between the substrates, thereby fixing the pair of substrates together. The irradiation conditions were such that the substrate was placed at a distance of about 20 cm from an ultraviolet lamp of 100 W/cm, and the substrate was irradiated for about 5 minutes. In this way, the light control layer 5 containing the transparent solid material and liquid crystal was formed, and at the same time, both substrates were fixed to complete a liquid crystal electro-optical device as shown in FIG. 1(C).

The uniformity of the substrate spacing in this fabricated device is 2.
It was 10.0 μm±0.1 for a 00 mm×260 mm substrate, and the spacers between the substrates were not unevenly distributed due to screen printing during the production of the light control layer and were appropriately dispersed within the substrate.

In the case of this example, it was not necessary to remove the solvent after coating the light control layer, and it was very effective in increasing the area. Furthermore, it has been effective to add heat treatment during or after polymerization of the monomer to increase the degree of adhesion of the substrate.

[0022]

[Embodiment 3] This embodiment will also be explained using process diagrams of the manufacturing method as shown in FIG. The substrate used is a transparent electrode 3 with a thickness of 200 mm on an ordinary blue plate glass 1.
ITO with a thickness of 0 Å formed into a predetermined pattern was used. Spacers 4 having an average particle size of 10.5 μm were sprinkled on the electrode surface side of this substrate by a wet method. This spacer is a composite of an internal hard spherical part and an organic substance on the external surface, and is dispersed in a mixed solvent of methyl alcohol and chlorofluorocarbon. In this dispersed state of FIG. 1 (A), 150
Heat treatment at ~200°C (180°C in this example) for approximately 1
This was carried out for 5 minutes, and at the same time as the solvent was removed, the organic matter on the outer surface of the spacer was dissolved, and the spacer was bonded and fixed to the substrate surface.

Next, a uniform mixed solution of prepolymer and nematic liquid crystal was formed to a thickness of about 15 μm by screen printing. Trimethylolpropane triacrylate was used as the prepolymer, and a homogeneous solution was used in which it was mixed with a polymerization initiator at a ratio of about 25% to a normal nematic liquid crystal material. Next, stack the other substrate in a predetermined position and press it with a pressure of 1 to 5 kg/cm2 so that the thickness becomes about 10 μm, and remove the unnecessary uniform solution between the substrates. I pushed it out. Next, the parts of the pair of substrates other than those that overlap are masked to prevent light from being irradiated, and the substrates are irradiated with ultraviolet light to harden the monomer (polymerization), forming a transparent solid material and liquid crystal. A light control layer containing the above was formed, and a pair of substrates were fixed together. This irradiation condition is about 20cm for a 100W/cm ultraviolet light lamp.
The substrate was placed at a distance of 1000 mL, and irradiated for about 5 minutes. After this, the surrounding areas that are not irradiated with ultraviolet light are cleaned with an organic solvent, the mixed homogeneous solution that protrudes from the substrate is removed, and the substrate is fixed, completing the liquid crystal electro-optical device as shown in Figure 1 (C). did.

In the case of this embodiment, when removing the mixed homogeneous solution protruding from the substrate, the electrode extraction portion of the substrate can be cleaned at the same time, which improves the connection with the liquid crystal drive electric circuit later and improves reliability. I was also able to improve my sexuality.

In the embodiments described above, other coating methods may be employed for coating the light control layer, if necessary. In this case, it can be appropriately selected depending on the components, viscosity, and characteristics of the solution used.

Although a composite spacer was used as the spacer, after forming a photosensitive organic material on the entire surface of the substrate, light was irradiated only on the necessary areas using a prescribed mask, and after development, the organic material was left behind and placed at any desired position. A spacer may also be provided.

[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 substrate spacing without biasing the spacers and with a small number of steps at a low cost. Furthermore, since the spacers are not biased, uniform display can be achieved without uneven display.

[Brief explanation of the drawing]

FIG. 1 shows a manufacturing process diagram of a liquid crystal electro-optical device of the present invention.

[Explanation of symbols]

1 Board 2 Board 3 Electrode 4 Spacer 5 Light control layer

Claims (3)

[Claims] 1. A method for manufacturing an electro-optical device having a pair of substrates, at least one of which is transparent, having an electrode layer, and a light control layer containing a transparent solid substance and a liquid crystal material between the pair of substrates, the method comprising: A step of dispersing spacers on the electrode surface side of one of the pair of substrates, a step of fixing the spacers on the electrode surface side of the substrate, and a step of forming the light control layer after the step. A method for manufacturing a liquid crystal electro-optical device, comprising the steps of: and bonding the pair of substrates together in a predetermined positional relationship. 2. A method for manufacturing an electro-optical device comprising a pair of substrates, at least one of which is transparent, having an electrode layer, and a light control layer containing a transparent solid substance and a liquid crystal material between the pair of substrates, the method comprising: A step of dispersing spacers on the electrode surface side of one of the pair of substrates, a step of fixing the spacers on the electrode surface side of the substrate, and after the step, applying the light control layer by a coating method. a step of forming, and after the step, bonding the pair of substrates in a predetermined positional relationship,
1. A method for manufacturing a liquid crystal electro-optical device, comprising a step of fixing by applying light irradiation, heating, or both. 3. A method for manufacturing an electro-optical device comprising a pair of substrates having electrode layers, at least one of which is transparent, and a light control layer containing a transparent solid substance and a liquid crystal material between the pair of substrates, comprising: A step of dispersing spacers on the electrode surface side of one of the pair of substrates, a step of fixing the spacers on the electrode surface side of the substrate, and after the step, applying the light control layer by a coating method. a step of forming, and after the step, bonding the pair of substrates in a predetermined positional relationship,
The method includes the steps of: masking the portions other than the overlapping portions of the pair of substrates and irradiating the transparent solid material with light to polymerize the transparent solid material; and removing the non-polymerized light control layer around the substrates. Characteristic method for manufacturing a liquid crystal electro-optical device.