JPS61193127A - Transparent conductive film integrally formed with polarizing film - Google Patents

Abstract

PURPOSE:To make a simplicity in the production steps of TN type liquid crystal display element and to enable to depress the production cost by integrating the transparent conductive film and the polarizing film. CONSTITUTION:The polarizing element is formed by laminating a polysulfone type film on at least one of surfaces of polyvinylalcohol type polarizing film contg. a dyestuff having a heat resistance property as a supporting layer, and by laminating a transparent insulating layer and a transparent conductive film in order, and by laminating a transparent metal oxide layer having a UV adsorping effect on an another surface of said laminated film. The supporting layer 2 of the polarizing film is a high polymer film having a good transparency, an optical isotropic and an excellent heat resistance properties. The transparent insulating layers a is a layer for preventing permeations of a humidity and an oxygen, and a migration of an ionic substance. The transparent conductive substance layer 4 laminated on the insulating layer is composed of nobel metals such as gold and palladium, and metal oxides such as stannic oxide and indium oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transparent conductive film integrated with a polarizing film used as a TN (twisted nematic>m) liquid crystal display element.

[Prior art]

Conventionally, in order to simplify the manufacturing process of TN type liquid crystal display elements and reduce costs, an organic polymer film is used as the support layer of the polarizing film, and a transparent conductive film is provided on the surface of the film, and the polarizing film and transparent Consideration has been given to integrating it with a conductive film. As a support layer for polarizing film,
Traditionally, acetate-based materials, such as triacetate A/loin film (TAC film), have been used.
When considering an integrated type, TAG film has a drawback in that it has low heat resistance and cannot withstand the sputtering and vacuum deposition conditions for forming a high-quality transparent conductive film and the assembly conditions of a liquid crystal display. Moreover, the low heat resistance makes it unsuitable for use as a support layer for a polarizing film. Furthermore, iodine, which has been conventionally used as a polarizing element, does not have sufficient heat resistance because it begins to sublimate at a temperature of 80 to 100°C.

Furthermore, films such as polyester, which have been conventionally considered as transparent conductive films, are stretched and oriented in order to bring out their polymer properties, and therefore have dioptric optical anisotropy. This optical anisotropy was a fatal flaw in the TN type liquid crystal display element C2, which utilizes polarized light.

In addition, the film that is the outermost layer (the layer that is first exposed to ultraviolet rays) when a liquid crystal display element is assembled and the dye that serves as the polarizing element of the polarizing film have poor weather resistance, so ultraviolet rays can cause a decrease in strength and cause cracks. Since deterioration phenomena such as generation, coloring, and fading occur, the display quality and life of the liquid crystal display element are reduced.

[Purpose of the invention]

The present inventors have achieved T by integrating a polarizing film and a transparent conductive film, which was previously difficult to achieve
In order to simplify the manufacturing process of N liquid crystal display elements and reduce costs, we used a polymer film with excellent heat resistance and optical (biisotropic properties) as the support layer of the polarizing film, and By sequentially laminating a transparent insulating layer and a transparent conductive layer on the surface, gas barrier properties,
Transparent conductive material with integrated polarizing film that has excellent water vapor barrier properties and ion barrier properties, and can be used as a material for TN-type liquid crystal display elements with excellent weather resistance by laminating a transparent metal oxide with ultraviolet absorption effect on the other surface. As a result of intensive studies to provide a transparent film, we have arrived at the present invention.

[Structure of the invention]

In the present invention, a polysulfone film is laminated as a support layer on at least one side of a polyvinyl alcohol (hereinafter abbreviated as PVA) polarizing film containing a heat-resistant dye as a polarizing element, and one surface of the laminated film is A transparent integrated polarizing film characterized by laminating a transparent insulating layer and a transparent conductive film on one surface, and a transparent metal oxide layer having an ultraviolet absorption effect on the other surface. It is a conductive film.

The structure of the polarizing film single-temperature transparent conductive film of the present invention is as follows.
The configuration will be explained according to the figures.

In the figure (;, (1) is a PVA-based polarizing film, which is obtained, for example, by the method described in U.S. Pat. No. 2,306,108, U.S. Pat. A PVA film produced by a general method such as extrusion is stretched uniaxially or biaxially about 3 to 4 times, and a dichroic dye having a heat resistance of at least 120°C for 2 hours or more is adsorbed. or PV
It was obtained by dyeing the stock solution of A, rolling it out, and stretching it.

<2) is a support layer for the polarizing film, and is a polymer film with good transparency, optical isotropy, and excellent heat resistance.
More specifically, the birefringence is within the frequency of the phase difference,
In addition, the photoelastic constant is 2.0-gradient or less, and the temperature at 200°C
It is suitable that the heat shrinkage rate is 5% or less.
Specifically, polysal 7on, polyethersal 7on,
Polysulfone films such as polyarylsulfone are suitable. In particular, it is desirable to use polyether sal 7one (hereinafter abbreviated as PES) film, which has excellent properties. Polysal 7-based film has transparency, mechanical strength, etching resistance, and organic solvent resistance necessary for a transparent electrode for a TN type liquid crystal display element. In addition, since the glass transition temperature Tg is 150°C or higher, P
By pasting it on at least one side of the VA (Tg = 100° C. or less) polarizing film, deterioration of the polarizing properties can be prevented.

In the figure, (3) is a transparent insulating layer, which is a layer for preventing the permeation of water vapor and oxygen and the migration of ionic substances, which are disadvantages of liquid crystal display elements using polysal 7 film. Specifically, S iox (X=1~2
), T ion, Z rob, A110B
, Ta205, Nb105, CeO2, and ZnO. The thickness of these metal oxide layers is I! #ζ: Not limited to 10
A range of 0 to 5,000X is preferred. If it is less than 100X, it is difficult to form a continuous film, and it is difficult to prevent the permeation of water vapor and oxygen, and to prevent the migration of ionic substances. Undesirable.

Note that Japanese Patent Publication No. 53-12953 reports a transparent flexible plastic film having air permeability and moisture permeation resistance provided with a transparent thin film layer of a silicon compound, but the polarizing film-integrated transparent conductive film of the present invention In addition, in the present invention, silicon oxide is handled not only to provide gas barrier properties, but also to prevent the migration of ionic substances from the support side to the conductive layer side, which will be described later. Moreover, it is provided to provide weather resistance. Furthermore, by using a PVA-based polarizing film having high gas barrier properties, an integrated film with excellent gas barrier properties can be obtained.

For the transparent conductive material layer (4) laminated on the insulating layer, a noble metal such as gold palladium or a metal oxide such as tin oxide or indium oxide is selected. General (Second is ITO (I.

A composite oxide mainly composed of indium oxide and containing 5 to 15% by weight of tin oxide is used.

When a liquid crystal display element is assembled, the layer exposed to the outside (the layer that is first exposed to ultraviolet light), that is, the transparent conductive material layer (4
) The polymer film on the opposite side and the dye that serves as the polarizing element of the polarizing film have poor weather resistance and deteriorate due to ultraviolet rays. (5) is a layer to prevent this, and S
iOx (x=1~2),sb,o,,CeF"
At least one member is selected from the group of transparent metal oxides such as , , The, , Ce01, etc. Especially 5iOx (x=1~
2), Sb! 08, CeF3 is desirable because it effectively cuts out light rays of 200 to 300 nm that cause yellowing of PES films.

Methods for laminating the insulating layer (3), the transparent conductive material layer (4), and the ultraviolet absorbing layer (5) include vacuum evaporation, sputtering, ion blasting, and plasma C.
Although general thin film forming techniques such as VD method can be used, RF magnetron sputtering method is particularly suitable.

In addition, when laminating PVA-based polarizing films (= Borisa A/7-on films), in order to obtain sufficient adhesion strength, use a urethane resin-based, epoxy resin-based, silicone resin-based, or synthetic rubber-based adhesive. It is desirable to use an adhesive that has heat resistance of at least 120°C for 2 hours or more (
(6) in the figure). In addition, when laminating an insulating layer (3) and an ultraviolet absorbing layer (5) on a Polysal 7-based film or a PVA-based polarizing film, an ultraviolet curable resin composition based on epoxy acrylate, urethane acrylate, etc. is used as an underlayer. By using it as a coating agent, more stable quality can be obtained ((7) in the figure).

〔Effect of the invention〕

By using the transparent conductive film integrated with a polarizing film according to the present invention, continuous reel-to-reel processing of long objects, which was previously impossible with transparent conductive films on glass substrates, becomes possible. Since the labor of incorporating a polarizing film in the display element assembly process is completely eliminated, the manufacturing process and manufacturing man-hours for TN type liquid crystal display elements are dramatically simplified.
This makes it possible to significantly reduce costs. Furthermore, it has the high heat resistance required when laminating transparent conductive layers and assembling a liquid crystal display element, and the optical isotropy necessary for a TN type liquid crystal element, which was insufficient in conventional polysal 7-based film liquid crystal display elements. Since gas barrier properties, water vapor barrier properties, and ion barrier properties can also be improved, it is suitable for use in TN type liquid crystal display elements.

In addition, by providing an ultraviolet absorption layer, weather resistance is improved, so ultraviolet rays can reduce strength, cause cracks, and cause discoloration.
It does not cause deterioration such as fading, and the display quality does not deteriorate even after long-term use.

Therefore, the reliability and life of the liquid crystal display element can be greatly improved compared to conventional ones.

〔Example〕

By solution casting method from polyvinyl alcohol aqueous solution, P
A VA film is formed and stretched uniaxially by a longitudinal stretching device for 3
~4 times; Stretched twice. Next: 1 = immersion in a dye bath containing a heat-resistant dye having dichromatic properties to adsorb dye molecules to create a base film of a heat-resistant polarizing film.

On the other hand, the PES film was extruded using a T-die extruder, and
A film with μ-like thickness was obtained. Using this PES film as a support layer, it was laminated on both sides of a PVA polarizing film via a urethane adhesive, and the film was left to stand at 40° C. for 72 hours to bond.

An undercoat agent was applied to one PES surface of the above polarizing film, and it was fixed to a substrate holder of a high frequency magnetron sputtering device, and 5in2
It was formed to have a thickness of 00λ. Then, using a target consisting of indium oxide containing 7.5% by weight of tin oxide,
30 in argon plasma at X 1O-3Torr
A transparent conductive film with a thickness of 0λ was laminated.

Further, the other PES surface was also undercoated, and a film of Sin was formed as an ultraviolet absorbing layer to a thickness of 2,000 mm by sputtering.

When the optical properties of the obtained transparent conductive film with integrated polarizing film were measured using a photospectrometer, the single transmittance in the wavelength range of 380 to 780 nm was 45%.
The degree of polarization was 90%.

An accelerated weathering test of this transparent conductive film with integrated polarizing film was conducted using an ultraviolet carbon feather meter.
Even after 400 hours of testing, no changes in properties such as single transmittance and degree of polarization, and no deterioration phenomena such as a decrease in film strength or coloring were observed.

Further, a TN type liquid crystal display element was prepared using the obtained polarizing film-integrated transparent conductive film by the following method. A positive photoresist was applied to the transparent conductive back side of the film using a wheeler, and after prebaking at 80°C for 20 minutes, u, v,
G-light was performed. Next, the film was post-baked for 20 minutes, the resist was removed, the resist was removed, and hot-melt adhesive was applied to one electrode side of the film that had been buttered. Cut it into a turn shape, sprinkle glass fiber strips with a column diameter of about 10 μm as a spacer on the other electrode side, overlap both films, and heat at 140°C.
The adhesive was dissolved and the cell assembled.

Next, nematic liquid crystal was injected through the opening prepared in advance using a vacuum injection method, and the opening was sealed with adhesive.

If the polarizing film is not an integral type, then the polarization direction must be aligned and the polarizing plate must be attached. However, if the polarizing film is an integral type, this step can be omitted, which simplifies the process and reduces costs.

When the obtained liquid crystal display element was subjected to an accelerated weathering test in the same manner as described above, no deterioration in the function as a liquid crystal display element due to deterioration of the liquid crystal material, deterioration of the cell, etc. was observed.

[Brief explanation of the drawing]

1 to 4 are schematic cross-sectional views showing the structure of the transparent conductive film with integral polarizing film of the present invention.

Claims (1)

[Claims] A polysulfone film is laminated as a support layer on at least one side of a base film of a polyvinyl alcohol polarizing film containing a dye having heat resistance as a polarizing element, and an insulating layer having transparency on either surface of the laminated film, and 1. A transparent conductive film integrated with a polarizing film, characterized in that transparent conductive films are laminated one after another, and a transparent metal oxide layer having an ultraviolet absorption effect is laminated on the other surface.