JPH04181215A - Production of liquid crystal display element substrate - Google Patents

Abstract

PURPOSE:To eliminate the unequalness of a coated film and the failure of a substrate, etc., by having a smooth and flat layer formed by a pressurized sliding method using an org. high polymer having the molecular structure to allow easy free rotation. CONSTITUTION:Colored films 2 are formed in the form of stripes having 90mum width and about 2.0mum film thickness as color filters on the glass substrate. The surface undulations of the films 2 are kept at 1.0mum max. step. A xylene soln. of polymethyl methacrylate having 2,000 average mol. wt. and 1,500 to 2,500mol.wt. distribution is applied thereon under pressurized sliding with a roll coater 6 and thereafter, the substrate is rested at room temp. and is then heated to 200 deg.C to obtain 4mum film thickness after heating. The surface undulations of this time are 0.1mum max. step and decrease considerably from 2.0mum thickness and 1.0mum max. step of the initial film 2. The film is thus smoothed and flattened. The film deposition and photolithographic characteristic are improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a liquid crystal display element as a display device, a method of manufacturing the same, a liquid crystal display element substrate used in the liquid crystal display element, and a method of manufacturing the same.

2. Description of the Related Art Substrates used in liquid crystal display devices require smoothness and flatness, and if these characteristics are lacking, the gap between the two substrates in the liquid crystal display device becomes uneven and the display quality deteriorates. This effect is particularly noticeable in STN type liquid crystals.

Here, smoothness is a performance related to roughness consisting of fine irregularities, and is generally referred to as smoothness.

Furthermore, flatness refers to the performance related to the undulations of the substrate, and is generally referred to as flatness.

In addition, if the substrate surface has undulations, when a thin transparent conductive film is formed on top of the substrate, disconnections or sheets are likely to occur in the transparent conductive film, and in the case of color filter substrates, light diffusion due to surface undulations may cause light transmission. may be damaged and the function of the color filter may deteriorate. Although several attempts have been made to smooth and planarize the substrate, a method in which a coating film layer is provided on a color filter will be described as an example of a conventional method.

FIG. 4 shows a cross-sectional view of a substrate on which a transparent coating layer is formed on a color filter. In FIG. 4, a color filter colored film 2 is formed on a glass substrate 1 to a thickness of several micrometers, and on top of this a coating film of varnish made of modified silicone, epoxy, acrylic resin, etc. is applied to a thickness of several micrometers. Layer 4 was formed.

Problems to be Solved by the Invention However, in the case of liquid crystal display element substrates, the above-mentioned method of coating a general resin to form a smoothing and flattening layer produces extremely fine pock-like undulations on the surface of the coating layer. It is difficult to obtain a high level of smoothness and flatness, especially for STN type liquid crystals, as the surface of the color filter and the colored film of the color filter themselves remain uneven or uneven. Ta.

The press molding method, which transfers the surface condition by pressing a press plate that has been smoothed and flattened, can achieve smoothness and flattening, but it is a contact method, and it is difficult to transfer surface defects such as the press plate and the adhesion of dirt. , the substrate was easily damaged during pressing and peeling. In addition, it was necessary to use consumables such as a press plate and a special press molding device.

In view of the above problems, the present invention provides smoothness and smoothness with a simple manufacturing method.
The purpose is to easily and inexpensively provide a substrate with high flatness that can be used for liquid crystal display devices.

Means to solve the problem Organic polymer resin with a molecular structure that can easily rotate freely.
Roll coat curtain coat, etc. After being coated onto the substrate using a pressure sliding method in which it slides along the surface while maintaining a constant distance from the substrate, it is heated to a temperature higher than the liquid flow temperature of the organic polymer. Providing energy to encourage free rotation of molecules,
A substrate with good smoothness and flatness with small waviness and surface roughness can be obtained.

Function: When a solvent or the like is added to the organic polymer resin to lower its viscosity and then applied or heated, smoothing progresses due to flow. This is used industrially as leveling. However, commonly used methods rely on solvents etc. to reduce the viscosity.
The molecular weight of the organic polymer used is large, hundreds of thousands of thousands, and its distribution is large, resulting in insufficient fluidity. As a result, the degree of smoothness and flatness was insufficient to achieve the level required for STN type liquid crystals, etc., and steps in the base remained and extremely fine undulations occurred on the surface. Further, the chemical resistance and solvent resistance of the coating film were sometimes insufficient.

If an organic polymer resin has molecules that can freely rotate in its molecular structure, it will actively flow due to the energy given to it (
Literature: Polymer Materials Handbook, published in 1970, edited by the Society of Polymer Science, published by Corona Publishing, p. 1076), by reducing the molecular weight,
In addition, it is made of a material that has a small molecular weight distribution and activates the free rotation of the molecular chain, which is the minimum active segment, and by applying thermal energy higher than the liquid flow temperature of this resin, free rotation of molecules occurs and flow. As a result, the viscosity of the resin itself is extremely reduced. As a result, surface roughness is removed, high smoothness is obtained, and the surface is uniformly expressed over a wide area. In addition, due to the pressurized sliding, the undulations caused by the substrate are buried and compressed, and the flatness is improved by removing the undulations.

After forming the organic polymer resin layer on the substrate by the pressure sliding method in this manner, a substrate having good smoothness and flatness can be obtained by a series of steps of applying ripening energy.

Example An embodiment of the present invention will be described below with reference to the drawings.

First, the color filter substrate shown in FIG. 2(a) is printed with red (R) on a glass substrate 1 by an intaglio offset printing method.
, green (G), and blue (B) inks to form a colored film 2 (2R) as a color filter.

2G, 2B) with a width of 90 μm and a film thickness of approximately 2.0 μm. The surface undulations (R,
The height difference between G and B was 1.0 μm at the maximum step. Here, the average molecular weight is about 2000, and the molecular weight distribution is 1500.
~2500 xylene solution (45% concentration) of polymethyl methacrylate was coated under pressure with a roll coater 6 having a roll diameter of about 100 mm as shown in Fig. 3, left at room temperature, and then heated to 200 ''C. After heating, a film thickness of 4 μm was obtained (Fig. 1).The surface unevenness at this time was 0.1 μm at the maximum step, which was 2.0 μm compared to the original thickness of the colored film 2.
m and the maximum step difference, which is the difference in height between R, G, and B, 1.
The thickness is significantly reduced from 0 μm, achieving the goal of smoothing and flattening. Even at another measurement point 100 cm away, the maximum step difference was 0.1 Bm, which was uniform over a wide area.

In addition, the average molecular weight is 5000 (distribution approximately 3000 to 1000)
0) and 30,000 polymethyl methacrylate, the maximum step difference was 0.6 μm, 0.7 μm.
μm, and smoothing and flattening could not be obtained. In this way, we confirmed the effectiveness of organic polymers that have a small molecular weight and whose fluidity increases with the application of energy, that is, organic polymers that have a molecular structure that allows molecules to easily rotate freely.

In addition, the coating and adhesion formation are performed using a rotating method (spinner method).

We tried the pulling method (dip method) and roll coating method.

In the roll coating method, pressure is applied by a roller, while in the other two methods, pressure is not applied. An organic polymer with an average molecular weight of about 2000 is used, and the maximum step difference is 0.6, 0, 5, 0, respectively.
A thickness of 1 μm was obtained, confirming the effect of pressure-sliding coating.

In addition, since the resin to solvent ratio was high, the coating layer had a high density, and the chemical resistance and melting resistance were at a practical level.

In this example, polymethyl methacrylate was used, but similar effects were confirmed with other organic polymer resins such as polymethyl methacrylate and polystyrene. In addition to reducing the molecular weight to obtain active free rotation, -C
It is also possible to select a resin having a structure such as -C- that has many bonds that can easily rotate freely. Further, in addition to roll coating, other pressure-sliding coating methods such as curtain coating can also be used.

Effects of the Invention By applying and forming an organic polymer resin with a molecular structure that allows easy free rotation onto a substrate using a method that provides pressure sliding action, the original undulations of the substrate can be smoothed and flattened. be able to.

Furthermore, since the surface of the substrate is smooth and non-contact during flattening, it is possible to transfer surface defects such as pressure plates that occur when forming with the contact method, adhesion of dirt, unevenness of the coating film that is likely to occur during pressing and peeling, and It is possible to eliminate damage etc. Further, since no special processing equipment is required and no consumables such as a pressing plate are required, smooth and flat substrates can be easily obtained at low cost. Furthermore, when a thin transparent conductive film is formed on a substrate, since the surface of the substrate is highly smooth and flat, the deposited film 5 has good photolithography properties and the occurrence of disconnections and short circuits in the transparent conductive film is reduced. In addition, the color filter surface has high smoothness and there is no light diffusion phenomenon, so that the color filter function can be highly exhibited.

Furthermore, when assembled as a liquid crystal display element, the gap between the substrates becomes uniform, resulting in a high display quality.

Although the method of the present invention has a particularly excellent effect on smoothing the color filter surface, it is also possible to use inexpensive glass instead of polished glass by similarly treating the surface of ordinary glass. We can provide substrates, etc.
It can be applied to a wide range of substrates that require smoothness and flatness.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a color filter substrate on which a smoothing and flattening layer is formed according to an embodiment of the present invention, and FIG. A cross-sectional view of a color filter substrate before forming a flattening layer,
FIG. 2(b) is a cross-sectional view of a color filter substrate according to an embodiment of the present invention, after an organic polymer is adhered and formed by sliding under pressure, but before the molecules constituting the organic polymer are given free rotation properties. , FIG. 3 is a conceptual diagram showing how organic polymer resin is deposited using a roller coater in an embodiment of the present invention, and FIG. 4 is a conventional example, which is a cross-sectional view of a color filter substrate on which a coating film layer is formed. be. 1...Glass substrate, 2...Colored film (2
R: Red, 2G: Green, 2B: Place), 3...
Smoothing, flattening layer, 4... Coating film layer, 5...
. . . Color filter substrate, 1 . . . Roller coater and its constituent parts, 7 . . . Organic polymer resin. Name of agent: Patent attorney Haruaki Ogata and 2 others 3 Figure G-11 Roller〕-q-Eng.
- Kano Boar Number: +) It ”, 6 6” Koro
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Claims (4)

[Claims] (1) A method for manufacturing a liquid crystal display element substrate having a smooth and flat layer formed by a pressure sliding method using an organic polymer having a molecular structure that allows easy free rotation. (2) A liquid crystal display element substrate obtained by the manufacturing method according to claim (1). (3) A method for manufacturing a liquid crystal display element, comprising the method for manufacturing a liquid crystal display element substrate according to claim (1), which comprises a color filter for a liquid crystal display element. (4) A liquid crystal display element comprising the liquid crystal display element substrate according to claim (2), which is provided with a color filter for liquid crystal display elements.