JPS59148029A - Electrooptic device - Google Patents

Abstract

PURPOSE:To improve stability against a thermal secular change in orientation by providing a film of hardened PVA resin with an ethyl acetoacetate group on the surface of an electrode plate and orienting the film. CONSTITUTION:A segment electrode 13 patterned in a specific shape is formed on the inside surface of a substrate 11 made of a glass plate, etc., and the film 15 of a hardened polyvinyl alcohol resin with an ester acetoacetate group covers the electrode. The film 15 is dyed properly at a part 17 covering the electrode 17 and oriented by being rubbed in mutual crossing directions against one insulating film 14 provided on a opposed common electrode 16 (arranged on substrate 12). Consequently, poistive dielectric anisotropic nematic liquid crystal 18 arranged between both of them is oriented while twisted at 90 deg.. Then, polarizing plates 10 and 19 put in a cross Nicol state are arranged at the outside of the liquid crystal formed as mentioned above. Thus, an aging change of liquid crystal is suppressed to improve the stability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electro-optical device, and particularly to a liquid crystal display device using nematic liquid crystal having positive dielectric anisotropy.

Nematic liquid crystal (abbreviated as N-liquid crystal) has an electric field, a magnetic field,
It is known that changes in optical characteristics due to the application of ultrasonic waves or the like can be used for display and can be used for light modulation and the like. This is usually an N-liquid crystal sandwiched between two substrates, at least one of which is transparent, which are placed facing each other with an interval of about 50 μm or less, and molecules that are generated by applying electric fields, magnetic fields, ultrasonic waves, etc. Changes in the arrangement are used for light modulation.

When an electric field is applied, an electrode plate is used as the substrate, which is a support plate such as a glass plate, and one surface of which is coated with a thin conductive coating.

The compounds that form the above-mentioned N-liquid crystals can be divided into two types (based on the relationship between molecular structure and dielectric properties).

One is a type in which the molecular axis and the electric dipole are approximately perpendicular (referred to as Nn), and the other is a type in which the molecular axis and the electric dipole are approximately parallel (referred to as Np). In means 9N-liquid crystal with negative dielectric anisotropy, and NP means N-liquid crystal with positive dielectric anisotropy. In the Np-liquid crystal electro-optical element commonly used in the past, there is an N between two opposing electrode plates.
It consists of a structure in which p-liquid crystal is sandwiched. In this case, the molecular axes of the Np-liquid crystal are parallel to the electrode plates, and the molecular axes are aligned in almost the same direction on the same plane parallel to the electrode plates, and the electrode plates are perpendicular to each other, so that adjacent planes are mutually oriented. Arrange in a continuous twisted direction.

It can be constructed by polishing the oriented and polarized surfaces of the molecular axes in one direction with cloth, paper, etc., and injecting liquid crystal between the two sheets stacked so that the polishing directions cross each other. It is known that near the electrode surface, the molecular axes are aligned in the polishing direction, but within the liquid crystal layer, the molecular axes are continuously twisted.

However, this method has the disadvantage that the orientation is not uniform and that the orientation is lost within a short time. Furthermore, it is known that orientation destruction occurs under heating.

As a method to solve these problems, it is known to use a large amount of surfactant to rub the electrode plate in one direction, but surfactant causes deterioration of the liquid crystal and makes it difficult to apply voltage. If this continues, the surfactant may be decomposed or altered by the electric field, and its orientation may be destroyed. Another method is known in which the surface of an electrode plate is coated with a certain amount of polymer such as polyimide or polyamideimide, and a single layer of the coated polymer is subjected to orientation treatment. However, polyamide and carbon films formed by dehydration and ring closure of a polyamic acid solution using a polar solvent such as dimethylacetamide have excellent heat resistance and orientation, but the processing temperature is 25°C.
At present, the temperature is as high as 0°C to 600°C or higher, and the solvent is a highly toxic polar solvent such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyridone, etc., so care must be taken when handling it. on the other hand,
Polyvinyl alcohol is a water-soluble resin that uses water as a solvent, and is not toxic like the solvents mentioned above and is easy to handle. It has some shortcomings.

It is an object of the present invention to provide a liquid crystal display device that has improved the above-mentioned points, and particularly to provide a liquid crystal display device that has improved alignment stability against heat and stability against aging γ.

It is an object of the present invention to provide an electro-optical device with an electrode plate in which the surface of the group provided with the conductive film is covered with a film of polyvinyl alcohol resin having a hardened acetoacetate ester group, and the surface is subjected to orientation treatment. In particular, this can be achieved by using it as an electrode plate constituting a liquid crystal display device.

The polyvinyl alcohol resin having an acetoacetate group used in the present invention can be obtained by adding diketene to a polyvinyl alcohol resin or transesterifying acetoacetate. In addition, polyvinyl alcohol resins include not only partially or completely saponified polyvinyl esters such as polyvinyl acetate, but also monomers mainly composed of vinyl acetate and copolymerizable with this, such as unsaturated carboxylic acids or partially or completely esters thereof. , salt, anhydride, amide, nitrile, unsaturated sulfonic acid or its salt,
"Copolymerization modified" polyvinyl alcohol, which is made by saponifying copolymers with α-olefins having 2 to 30 carbon atoms, vinyl ethers, etc. Acetalization, urethanization, etherification, grafting, phosphoric acid esterification, etc. of polyvinyl alcohol and polyvinyl alcohol. "Post-denatured" polyvinyl alcohol is also used.

The content of the acetate acetate group in the polyvinyl alcohol resin in the present invention can be as high as 0.05 mol% or more within the range of water solubility, but is usually 0.1
-40 mol%, preferably 0.2-20 mol%.

This polyvinyl alcohol resin is dissolved in water or alcohols (methanol, ethanol, inglobil alcohol, etc.), and added to this solution as a water-resistant insolubilizing agent such as ammonium dichromate, magnesium chloride, dimethylolated melamine, or dialdehydes. After adding the compound with two or more active groups, it can be cured under predetermined curing conditions. The dialdehydes mentioned above include glyoxal, malondialdehyde, succindialdehyde, glutaric dialdehyde, maleic dialdehyde,
Examples include phthalaldehyde, isophthalaldehyde, terephthalaldehyde, etc., with glyoxal and glutardialdehyde being preferred, and glyoxal being particularly preferred.

The amount of the curing agent can be 0.1 parts by weight to 100 parts by weight, preferably 1 part by weight to 50 parts by weight.

The aforementioned polyvinyl alcohol resins containing ammonium dichromate can be cured by appropriate light irradiation, especially ultraviolet irradiation, and the aforementioned polyvinyl alcohol resins containing dimethylolated melamines and dialdehydes can be cured by exposure to excessive temperatures. For example, it can be cured by heating at (180 to 200°C).

Methods for applying the polyvinyl alcohol resin used in the present invention on the electrode plate include a brush coating method, a dip coating method, and a spinner coating method using a solution prepared by adding, for example, ammonium dichromate and glyoxal as water-resistant insolubilizers to a polyvinyl alcohol aqueous solution. After being applied to the stained electrode plate by a spray coating method or a bar coating method, and dried, a polyvinyl alcohol resin film is formed which is cured under predetermined curing conditions.

This cured polyvinyl alcohol/')fd fatt
The v coating can be removed with a chromic acid (Cr05) aqueous solution, so for example, the aforementioned polyvinyl alcohol coating formed on the terminal part of the electrode plate and the seal spacer forming part during the process of manufacturing a display device is usually removed. It can be removed by using a photolithography process and an aqueous chromic acid solution. In particular, use of this chromic acid aqueous solution can prevent contamination of the seal spacer.

The polyvinyl alcohol resin film treated with this water-resistant insolubilizer is homogeneously aligned in one direction with cloth, etc.
For example, 2-ping processing is performed.

This orientation-treated polyvinyl alcohol resin film can improve stability and stabilize orientation over time.

As the electrode plate used in the liquid crystal display device of the present invention, at least one side is a transparent conductive film (for example, indium oxide, tin oxide, indium oxide-tin oxide (tin oxide: o, 1 to 40
It is preferable to use a substrate (glass, plastic, etc.) provided with a material (such as % by weight). Further, as the opaque conductive film used in the present invention, aluminum, gold, silver, copper, lead, etc. can be used.

The liquid crystal sealed in the display device of the present invention is not particularly limited, and various types can be used as appropriate. In particular, as a liquid crystal used in the above-mentioned twisted oriented nematic liquid crystal mode, a nematic liquid crystal with positive crocodile anisotropy, such as a nematic liquid crystal manufactured by West Germany (DrZL 1216J), is used.
, "zLany253J, [ZLI-1285J,"
ZI,, T-1414J, [zLany 565J -
? [ZLI-1694J etc. can be used. These liquid crystals can be used alone or in combination.

Hereinafter, a liquid crystal display device will be described as an example of the electro-optical device of the present invention, but the present invention is not limited thereto.

FIG. 1 is a Vr plane view of the display device of the present invention.

In FIG. 1, reference numerals 11 and 12 indicate substrates such as glass plates or sticky plates. A segment electrode 16 patterned into a predetermined shape is formed on the inner surface of the substrate 11, and a coating 15 of a hardened volibi resin having an acetoacetate group is formed thereon.
is covered. At this time, the segment electrodes 15 can be formed from a transparent conductive film such as indium oxide or tin oxide.

The aforementioned coating 15 has a portion 17 covering the segment electrode 13.
can be stained using an appropriate method to display half-colors and identify them. The coating 15 has an opposing common electrode 16
When alignment treatment is performed by rubbing in directions that intersect with one of the insulating films 14 provided above, the liquid crystal 18 disposed between them is twisted and aligned at an angle of 90°. As the liquid crystal 18 used in this case, a nematic liquid crystal (hereinafter referred to as Np liquid crystal) having positive dielectric anisotropy is used.

Polarizing plates 10 and 19 in a crossed nicol state are arranged outside the liquid crystal cell having such a structure.

In this liquid crystal display device, for example, when a voltage is applied between the segment electrode 16 and the common electrode 16 shown in FIG. 1, the molecular axis of the Np liquid crystal 18 is aligned in the direction of the electric field, so that incident light is blocked between crossed nicols. and can be seen as a black display 22 in a liquid crystal display device 21 as shown in FIG.
This black display 22 looks like a dyed color.
3 can be distinguished.

In the liquid crystal display device n shown in FIGS. 1 and 2, by using polarizing plates colored blue, gray, red, etc. as the polarizing plates 10 and 19, the color tone effect in this device can be enhanced.

Further, behind the polarizing plate 10, there is a reflecting plate (
(not shown) can be placed.

As a method for dyeing the portions 17 forming the segment electrodes 16, for example, a coating 15 is formed on a substrate having a transparent conductive coating patterned into a predetermined shape, and a coating of photoresist material is further applied on the coating 15. After forming, predetermined exposure and development are performed so that the portions other than the electrode portions described above serve as a mask, and then dyeing solution (for example, [8umix 5upper Brlliant manufactured by Sumitomo Chemical ■) is applied.
It can be done by immersing it in Red3BF (2% ammonia solution).

Hereinafter, the present invention will be explained according to examples.

Example 1 Polyvinyl alcohol having an acetoacetate group (
[Gosefa'17-Z200 manufactured by Nippon Gosei Chemical Industry ■
ammonium dichromate and glyoxal (ammonium dichromate: glyoxal =
i: i) was added in a proportion of 5% by weight based on the solid content of polyvinyl alcohol. This solution was applied onto the electrode plate for 10 seconds using a spinner coating machine rotating at 3000 rpm to form a film of 1500 A, and then dried by heating at a temperature of 200° C. for 30 minutes.

Next, in order to remove the coating on the terminal part and the seal spacer forming part of this electrode plate, a mask was formed on the part excluding the terminal part and the seal spacer forming part by using the usual 7-otoline process, and then this electrode plate was removed. The plate is coated with 10% chromium # (C
rO2) aqueous solution for 10 minutes to remove the film formed on the non-mask area. After that, the resist is peeled off and 1
Reheated at 80° for 15 minutes.

Next, a pair of electrode plates provided with a polyvinyl alcohol coating were aligned by rubbing in one direction with a cloth, and then cell-assembled so that the rubbing directions were perpendicular to each other. A display device was created by enclosing a cell (1ZL Knee 1253J) manufactured by Merck & Co., and then laminating polarizing films on both sides of the outside of the cell so that the polarization direction of the polarizing film was parallel to the rubbing direction of the adjacent substrate. (This is referred to as sample A1).

On the other hand, as a comparison sample, instead of the polyvinyl alcohol used when creating the display device of sample A1 described above, [Nb-osJ, manufactured by Nippon Gosei Kagaku Kogyo ■] was used as a polyvinyl alcohol that does not have acetoacetate. created a display device in the same manner as described above.

These samples were incubated at a temperature of 85°C and a relative humidity of 85% for 100 hours, 200 hours, 600 hours, and 4 hours, respectively.
A forced aging test was performed on each sample by storing it at intervals of 00 hours, 500 hours, and 1000 hours, and the increase in current in the liquid crystal display at each aging time was measured. As a result, sample point 1 according to the present invention showed an increase in current of less than 10% even after 1000 hours, and sufficient liquid crystal display ability was observed, whereas the comparative sample
The increase in current after 0 hours was 10% or more. or,·
In this comparative sample, sufficient display ability was observed even after 500 hours had passed.

Example 2 A display device was created in the same manner as in Example 1, except that dimethylolated melamine was used as the water-resistant insolubilizer used when creating Sample A1 in Example 1 (Sample A2).

When sample A2 was subjected to a forced aging test in the same manner as in Example 1, the current increase was less than 10% even after 1000 hours, and sufficient liquid crystal display ability was observed.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a liquid crystal display device of the present invention, and FIG. 2 is a plan view thereof. 11.12... Substrate 13... Segment electrode 14... Insulating film 15... Cured polyvinyl alcohol resin coating 16 having an acetoacetate group... Common electrode 17... Segment electrode 13 Part of the insulating film disguising (dyed part) 18...1 liquid crystal 10.19...polarizing plate 21...liquid crystal display device 22...display by drive 23...half display Patent applicant Canon Co., Ltd. Agent Marushima Gi-1: U and 1'! ! . Procedural Amendment (Voluntary) January 1, 1980, Japan Patent Office Commissioner Kazuo Ishibori■ Indication of the Case 1981 Patent Application No. 23471 2 Name of the invention Electro-optical device 3 Person making the amendment (Relationship with ++ Patent Applicant Address Shimomaruko r3-30-2, Hitogawa-ku, Tokyo Name (+00> Canon Co., Ltd. Address (7) 146 3-30- Shimomaruko, University 01-ku, Tokyo
2 "" 5. Specification and drawings to be amended 6. Contents of amendment (1) "Polarization direction" on page 14, line 12 of the specification is corrected to "polarization direction"0 (Figure 1 of 4 drawings Correct the drawing attached to the attached sheet.

Claims (6)

[Claims] (1) In an electro-optical device comprising a liquid crystal layer sandwiched between two substrates each having a transparent conductive coating on at least one side, at least one of the electrode plates has acetoacetic ester X hardened on its surface. 1. An electro-optical device comprising a coating of polyvinyl alcohol resin having a polyvinyl alcohol group, the coating being subjected to orientation treatment. (2) The electro-optical device according to claim 1, wherein the liquid crystal is a nematic liquid crystal having positive electrical protection anisotropy. (3) The electro-optical device according to item 1, wherein the cured polyvinyl alcohol resin having an acetoacetate group is cured within a predetermined range. (4) The electro-optical device according to claim 3, wherein the water-resistant insolubilizer is at least one compound selected from the group of compounds consisting of ammonium dichromate, magnesium chloride, dialdehydes, and dimethylolated melamine. . (5) The electro-optical device according to claim 4, wherein the water-resistant insolubilizing agent is glyoxal. (6) The electro-optical device according to claim 1, wherein the alignment treatment is a rubbing treatment, and a portion of the formed conductive film is colored.