JPS60229009A - Transparent conductive film for liquid crystal electrode - Google Patents

Abstract

PURPOSE:To enable application to a voltage impression type liquid crystal display device by using a polymer film having optical rotatory power, warping due to heating for 3hr, and shrinkage rate, each regulated to a specified value, respectively. CONSTITUTION:The polymer film used for the polymer film electrode base of the voltage impression type liquid crystal display device, having an optical rotatory power of <=15nm, can form a liquid crystal display image high in contrast. The cell gap of the device is made uniform when the warping of the film is <=5mm./40mm., and rainbows like Newton rings caused by the warping tendency of the film are not found. When the shrinkage rate per hour is <=2.0%, deformation of the segments due to heat shrinkage is not found and trouble that a part of lead wires intrudes in the liquid crystal image does not occur. Preferable polymer film to be used is optically isotropic films selected from polycarbonate, polysulfone, polyimide, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a transparent conductive polymer film forming an electrode substrate sandwiching a liquid crystal material.

[Prior art]

Conventionally, a transparent conductive glass substrate has been used for the electrode substrate C of the liquid crystal display element, but the glass substrate is easily broken and the display body is easily damaged even during one assembly process or after completion.
In addition, it is said that the limit for thickness is Q, 3tn/m (= it is said that it is difficult to make it thinner. Therefore, it has the drawback that it is difficult to make it thinner and mass-produced. However, when using a polymer film as an electrode substrate for a voltage-applied type liquid crystal display element in which a polymer film is combined with a polarizing plate to form a pair of transparent electrodes that sandwich a nematic liquid crystal material, the molecular Orientation flea - Due to the presence of optical rotation, which is the product of birefringence and thickness (: Therefore, during liquid crystal display (:
The drawback was that it was not possible to obtain clear images with high contrast.

Also, when assembling a liquid crystal cell (a thermosetting adhesive is used, if the film is warped due to heating), the distance between the electrodes of the liquid crystal cell changes, and the optical path length in the liquid crystal changes. Display C had the disadvantage that a rainbow in the form of two Newton rings was produced.

(2) When the film itself shrinks due to heating during assembly of the liquid crystal cell (2), the film that becomes the electrode substrate (
The circuits of the double-patterned common electrode and segment meter electrode sandwich the liquid crystal layer, resulting in misalignment, the shape of the image is different from the set shape, or a part of the lead wire is missing from Image 1:
When the image appeared, it had the disadvantage of becoming an ugly thing.

[Purpose of the invention]

The present invention is designed to solve the problem that when trying to apply a polymer film substrate used in a conventional voltage application type liquid crystal display element (2), it is difficult to obtain an image with high contrast due to the optical rotation aperture of the film, and the liquid crystal display (2) is prone to warping. In view of the fact that a two-Newton ring-shaped rainbow appears, and heat-shrinkable liquid crystal displays (elite lines are projected), we are actively researching the characteristics of voltage-applied liquid crystal display elements (= suitable polymer film substrates). As a result, we arrived at C2, which completes the present invention.

[Structure of the invention]

The present invention provides a liquid crystal display element (2) surface of a polymer film forming electrodes that sandwich the liquid crystal substance used (2) a polymer film provided with a transparent conductive thin film, the optical rotation of the polymer film being 15 nm or less and 150 nm or less. When heated for 3 hours at ℃ (= the warpage is 5 m or less per 401111, and 20
A transparent conductive polymer film characterized by a shrinkage rate of 2.0% or less when heated at 0° C. for 1 hour.

The present invention (-Polymer films used include polycarbonate, nate, polysulfone, polyethersulfone,
polyetherimide, poly-4-methylpentene-1,
An optically isotropic film selected from films such as polyimide is desirable.

Methods for creating such films include extrusion molding, casting molding, and rolling molding.
The thickness of the film is in the range of 10 to 500 μm, preferably in the range of 20 to 200 μm.

In addition, the transparent conductive layer to be molded is formed using the polymer film (= the side in contact with the liquid crystal layer). Forming methods for such a conductive layer include vacuum evaporation, chemical vapor deposition, sputtering, spraying, etc. Among these methods, vacuum evaporation method and sputtering method are preferable.In addition, considering the heat resistance of the film, low-temperature sputtering method is more preferable.

In the case of the vacuum evaporation method, the formed metal film is usually made transparent by heating oxidation, but at a temperature of 200°C (when heated twice,
Polymer films with low heat resistance may not be used, which is inconvenient. When using low-temperature sputtering method, under a vacuum of 3×10 to 10 (Torr),
200-1000 directly at a formation rate of about 0'A/SeC
A large transparent conductive layer can be obtained, and thermal oxidation treatment can also be omitted.

When an ITO film is used as a conductive layer, the conductivity of the transparent conductive layer thus obtained is about 100 to 5,0 OOQ/D when the thickness of the ITO film is about 300λ, and as an electrode substrate for a liquid crystal display element. Q/D or less is desirable.

The optical rotation referred to in the present invention is determined by determining the extinction position of the sample in a cross-null state using a polarizing microscope, rotating the sample by 45 degrees from the extinction position, confirming that the interference color changes to the lower order side (two changes), and rotating the analyzer. The angle of rotation of the analyzer at which the darkest point occurs can be read.

If the optical rotation is 15 nm or less, a high contrast image can be obtained on a liquid crystal display.

In the present invention, non-warpage means that the film has a width of 10 mm and a length of 5 mm.
01IME, fixed the 10-inch length part at one end, and treated at 150°C for 3 hours at the tip position (; This shows that the distance that fluctuated was less than 5u. In other words, the non-warping property was If it is about 491111 and 5111 or more, the cell gap becomes partially non-uniform and a 22-ton ring-shaped rainbow becomes visible.

Moreover, non-shrinkability indicates that the shrinkage rate at C2 when the film is heated at 200° C. for 1 hour is 2.0% or less.

That is, if the heat shrinkage rate is 2.0% or more, the shape of the segment in the liquid crystal display will change or a part of the lead wire will appear as an image (2).

〔Effect of the invention〕

According to the present invention (2), if the optical rotation of the polymer film used in the voltage applied liquid crystal display element (2) is 15 nm or less, images with high contrast can be obtained in the liquid crystal display (2). .If the anti-warpage property of the film is 5 m/m or less per 40 fi/m, the cell gap is uniform (2), liquid crystal display (2).

Newton's ring-shaped rainbows caused by the warpage of the film are not observed. In addition, if the heat shrinkage rate, which is defined as non-shrinkability of the film, is 2.0% or less, the liquid crystal display (2) may be affected by changes in the shape of the segments due to heat shrinkage, or if part of the lead wire is not displayed as an image. It will never be shown.

〔Example〕

Using ICI's 'vIcTREx' polyether sulfone resin, a T-die extruder (two-way thickness 10,100 liters) was used.
The optical rotation angle was 15 m from the film obtained from this film.
In the following, we will select a part with a non-warping property of 10 per 40111 and a non-shrinkage property of within 2.0%, and use it as a liquid crystal display using a transparent conductive film on which an ITO film having a thickness of about 3001 is deposited. When used as an electrode of a device, high contrast was obtained, no Newton's ring-shaped rainbow or part of the lead wire was visible, and an image was obtained with no change in the shape of the segments.

Claims (1)

[Claims] A polymer film provided with a transparent conductive thin film forming electrodes that sandwich a liquid crystal substance (=, where the optical rotation of the polymer film is 15 degrees below the plate and 150°C for 3 hours) When heated (the warpage at the second holder is 50 or less per 40'B, and 20
The shrinkage rate when heated at 0℃ for 1 hour. A transparent conductive film for liquid crystal electrodes, characterized in that the content is 2.0% or less.