JPH0266518A - Phase film integrated type transparent conductive film - Google Patents

Abstract

PURPOSE:To reduce the weight and thickness of the above film by integrating the phase plate of a transparent high-polymer film and a transparent conductive film. CONSTITUTION:A polysulfone film is laminated as a backing layer on at least one surface of the phase plate of the transparent high-polymer film and a transparent film having conductivity is laminated to at least one surface thereof. The transparent high-polymer film which has double refractiveness and is formed by controlling the retardation value so as to have nearly the same value as the value of an STN type liquid crystal panel is used as the phase plate. The high-polymer film having >=85% transmittance of 600nm ray, <=15nm double refractions as retardation <=2.0mm/kg photoelastic constant, and <=5% thermal shrinkage at 200 deg.C is adequate as the backing layer of the phase film. A composite oxide essentially composed of indium oxide is used as the transparent conductive material. The weight and thickness of the film are reduced in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to STN (Super Twist Material Ink)
A phase film-integrated transparent conductive film using a polysulfone film as a support layer on at least one side of a polymer transparent film phase film whose retardation value (Δn-d) is arbitrarily designed for use as a black-and-white liquid crystal display element. It is.

[Conventional technology]

Conventionally, in order to make STN type liquid crystal display elements color, various methods have been used to make them black and white.

Originally, in the optical mode, the linearly polarized light that entered the liquid crystal came out as elliptically polarized light due to the refractive index anisotropy and high twist angle, so it appeared colored blue-purple or yellow-green. In this state, it is impossible to colorize the device, but by placing a completely plane-symmetric STN type liquid crystal panel on top of this liquid crystal panel, this panel plays the role of a phase compensation plate, and the elliptically polarized light is The two-way STN system, which is based on the principle that light returns to its original linear polarization, makes it possible to display black and white, and the contrast is more than twice that of the original STN liquid crystal panel, making it possible to display gradations.

However, by making the liquid crystal panel two-layered, the panel becomes heavier and thicker, and two STN liquid crystal panels that require high precision must be manufactured, resulting in a considerable cost increase.

Therefore, in order to solve this drawback, in place of the phase compensation panel, a polymer transparent film phase plate, such as a temporary polycarbonate film, having the same retardation value as the STN type liquid crystal panel is laminated. Display liquid crystal panels became possible.

However, when bonding the phase plate together after the panel is manufactured, it is difficult to properly adhere the phase plate, including aligning the optical axis, and there are still many problems in mass production.

[Problem to be solved by the invention]

The purpose of the present invention is to integrate a polymeric transparent film phase plate and a transparent conductive film into a
In order to make the TN-type liquid crystal black and white display panel lighter and thinner, and to omit the process of aligning and bonding the phase 41 after panel fabrication, we aim to simplify the manufacturing process, improve yields, and reduce costs. An optically isotropic polymer film with excellent optical properties is used as the support layer of the phase plate, and a transparent organic polymer layer is provided on the surface to improve flatness. By doing so,
An object of the present invention is to provide a phase film-type transparent conductive film that can be used as an STN type liquid crystal display element material capable of displaying black and white with just a layer panel.

(Means for Solving the Problems) The present invention laminates a polysulfone film as a support layer on at least one side of a transparent polymer film phase plate, and coats one surface of the laminate film with a transparent conductive film. This is a transparent conductive film integrated with a phase film, which is characterized by being laminated.

The phase plate used in the present invention is a transparent polymer film having birefringence, and its retardation value is STN.
Birefringence is a film made by uniaxially stretching and aligning a resin such as vinylon, polyvinyl alcohol, polycarbonate, polystyrene nylon, butyl cellulose acetate, or cellophane, which is controlled to have almost the same value as that of a type liquid crystal panel. Sex Δn-0,001~0.1
The thickness d is 10 to 1100 II. (
Δn=d is 0.1 to 1.0 μm, preferably 0.9 μm
) It is also desirable that the material has a heat resistance of at least 120" CX for 2 hours or more.

For the support layer of the phase film, a material with good transparency, optical isotropy, and excellent heat resistance, more specifically, 600 nm
The light transmittance of m is 85% or more, the birefringence is +5 nm or less in terms of retardation, and the photoelastic constant is 2.
．． A polymer film having a heat shrinkage rate of 0 mm/kg or less and a heat shrinkage rate of 5% or less at 200°C is suitable.
Specifically, by using a polysulfone-based film such as polysulfone, polyethersulfone, biphenyl-modified polyethersulfone, or polyallylsulfone, it can be made into an integrated structure. In particular, it is desirable to use a polyether sulfone (hereinafter abbreviated as PES) film which has excellent properties. Polysulfone films have the transparency, mechanical strength, etching resistance, and solvent resistance necessary for transparent electrodes for liquid crystal display devices. In addition, the flatness of the film itself may be 0 or 1 μm due to guilines, bulges, foreign matter, etc.
Protrusions with a size of m or more in the thickness direction disturb the cell gap of the liquid crystal panel and cause color unevenness, so it is desirable that they be absent.

The transparent conductive material laminated on this surface is selected from noble metals such as gold and palladium, and metal oxides such as tin oxide and indium oxide, but is generally referred to as ITO (indium tin oxide). 5-15 weight 1%
A composite oxide mainly composed of indium oxide containing tin oxide is used.

Methods for laminating transparent conductive layers include vacuum evaporation, sputtering, ion blating, and plasma CVD.
General thin film formation techniques such as the method can be used. Particularly suitable is the sputtering method. When laminating a polysulfone film on the phase film, in order to obtain sufficient adhesion strength, use a urethane resin, epoxy resin, silicone resin, or synthetic rubber adhesive that has heat resistance of at least 120°C for 2 hours or more. It is preferable to use adhesive. Furthermore, when laminating a transparent conductive layer on the surface of a polysulfone film, more stable quality can be obtained by using an ultraviolet curable resin composition based on epoxy acrylate, urethane acrylate, etc. as an undercoat agent.

Furthermore, by laminating a transparent insulating layer on at least one surface of the polysulfone film and inside the transparent conductive layer, it is possible to prevent water and air permeation, prevent ionic substance migration, and provide sufficient weather resistance. The insulating layer is 5iOx (
X=1-2), TiO□, ZrCh, A1. O,,Ta
At least one member is selected from the group of transparent metal oxides: xes, NbzOs, CeO□, and ZnO. Furthermore, the opposite side of the conductive layer of the phase plate-integrated transparent conductive film of the present invention may be subjected to a hard code treatment or a mobile coating such as plasma treatment, corona treatment, etc. to improve the adhesion to the polarizing plate. good.

〔Example〕

The present invention will be further explained in detail by way of examples.

Example 1 A PVA phase film was obtained by stretching a PVA film produced using a coating device equipped with a doctor coater and a blow dryer in the longitudinal direction five times using a roll stretching machine. The total birefringence of this film was 0.03 (the refractive indices in the direction of the stretching axis and in the direction perpendicular to this were approximately 1.53 and 1.56), the thickness was approximately 30 μm, and the retardation value As a result, 0.9 was obtained. A 50 μm thick PES film was bonded to one side of this phase film as a support layer, and the same <50 μm thick PES film was bonded to the other side as a protective layer using a urethane adhesive.

The PES film serving as the support layer has already been undercoated on one side. This substrate was fixed to a substrate holder of a high frequency magnetron sputtering device with the undercoated side facing up, and a target made of indium oxide containing 7.5% by weight of tin oxide was used to 5X
A 300-meter-thick conductive film was formed in an argon plasma at 10-'' Torr to obtain a transparent conductive film integrated with a phase film of the present invention.

Application Example Using the phase film-integrated transparent conductive film obtained in Example 1, an STN type liquid crystal black and white display element was prepared by the following method.

The transparent conductive film of the film was patterned and used as a front substrate in the viewing angle direction, and a patterned transparent conductive film consisting of a PES film alone was used as a rear substrate.

An alignment film made of polyimide was formed on both electrode surfaces, and after considering the optical axis of the phase plate, a rubbing treatment was applied so as to twist it at 240°. Both boards are 5μ
A cell was assembled by inserting a spacer having an average particle size of m and bonding the particles together using an epoxy adhesive and curing with heat.

Next, using the vacuum injection method, nematic liquid crystal added with a chiral agent was injected through a pre-prepared opening.
The opening was sealed with adhesive.

By bonding a polarizing plate to this cell with an appropriate optical axis, a flexible STN type liquid crystal panel with black and white display was obtained.

If the phase plate is not integrated, it is necessary to align the axes before attaching the polarizing plate and then attach the phase plate. However, in the case of an integrated type, this step can be omitted, which simplifies the process and reduces costs. can.

Example 2 By the same method as in Example 1, one side of a PVA-based phase plate bonded with two PES films was undercoated, fixed to a substrate holder of a high-frequency magnetron sputtering device, and SiO2 was applied as a transparent insulating layer. 500
A thin film of ITO was then formed using tin oxide and indium oxide targets.

The 0□ barrier property of the obtained substrate was 0.1cc/rrf・
It was 2211rs・latm.

Example 3 A PVA-based phase film was obtained in the same manner as in Example 1. On the other hand, a photocurable resin composition was prepared using the formulation shown below.

(A) 100 parts by weight of urethane acrylate using isophorone diisocyanate as the isocyanate component (UV-3000B manufactured by Nippon Gohsei ■) (B) Epicoat #1004 (product name: Ebisu type epoxy manufactured by Yuka Shell Epoxy ■) 50 parts by weight of epoxy acrylate obtained by reacting resin) with acrylic acid (C) 2-hydroxypropyl acrylate -90〃 (D) 2-hydroxy-3-chloropropyl methacrylate-1---m--- 30 (E)2-methyl-1-(4-methylthiophenyl)-
2-morpholinopropan-1-one (Irgacure 9
07, manufactured by Ciba Geigy)...-3 (F) n-nonylphenoxyoxyethylene acrylate ------100 (G
) 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one (Darocur 1116
(manufactured by Merck & Co., Ltd.) The above PVA-based phase film was sandwiched between two PES films (70 μm thick) coated with this resin composition on one side, and the air interposed between the films and the excess resin composition was removed using a pressure roll. I pushed it out and made it stick. Immediately turn this on to 80W/a
2 m/m to an ultraviolet irradiation device equipped with two high-pressure mercury lamps
The film was fed at a line speed of 1.5 in., was irradiated with ultraviolet rays once, and then annealed by heating at 120"C for 5 minutes.

Table 1 shows the evaluation results of the beer strength of the obtained polarizing plate.

Table 1 Example 4 A solution obtained in the following formulation was applied as an undercoat layer to one side of the phase plate obtained in Example 3.

(A) Urethane acrylate prepolymer (molecules: 113,200, melting point: 55°C), a reaction product consisting of isophorone diisocyanate as an isocyanate component, 1.6 hexanediol as a polyol component, and 2-hydroxyethyl meccrylate as an acrylic component.
--30 parts by weight (B) Epoxy acrylate prepolymer (molecular approx. 1040, melting point 55°C1 VR90 manufactured by Showa Kobunshi ■) ---1 ---7
0(C) Benzyl alcohol -・-・300〃
(D) Ethylene glycol -・-・200〃(E
) Methyl isobutyl ketone -----150//(F)
Benzoin ethyl ether --- 2 As for the coating method, use a boiler and heat it at 80"C for 10 minutes to remove the solvent, then irradiate it with ultraviolet rays for 30 seconds at a distance of 15 cm using an 80 W/cn+ high pressure mercury lamp. This was done by curing the resin layer.The coating thickness was 2.5 μm.
Met.

A transparent conductive film having a thickness of 300 layers was deposited on this undercoat layer in the same manner as in Example 1 to obtain a phase film integrated transparent conductive film.

The adhesion of the transparent conductive film of the film was evaluated by the following method. First, as an evaluation of scratch resistance, the surface resistance was rubbed several times with gauze under a load, and the change in surface resistance value was less than a few percent.

Next, as an evaluation of alkali resistance, a method of immersing the sample in 10%-NaO)lH for 10 minutes was used, but there was almost no change in the surface resistance value and no cranking or the like occurred.

Example 5 A DC magnetron sputtering device was fixed to a substrate holder in a vacuum chamber for a phase plate obtained in the same manner as in Example 3.4 and required to be undercoated on one side, and the vacuum chamber was evacuated for 1 hour. The amount of gas generated at this time is 4 x 10-S
Next, a thin film of indium oxide/tin oxide composite oxide (rTo) was formed using a mixed gas plasma of argon and oxygen using a target made of an indium tin alloy. The characteristics of the obtained ITO thin film are a film thickness of 250 Ω and a surface resistance value of 300 Ω.
/ mouth, and the film was uniform with little variation depending on location.

Example 6 The surface of the transparent conductive film integrated with a phase film obtained in Example 1 on the side opposite to the transparent conductive film was subjected to plasma treatment. The liquid crystal cell with a polarizing plate attached to the film is 6
Humid and heat resistance test 5001 at 0°C and 90% RH (no peeling of the polarizing plate was observed even after rs had passed).

As is clear from the above description, according to the present invention, a film for an STN type liquid crystal black and white display element in which a phase film, a support layer, and a transparent conductive film are integrated and whose retardation value can be controlled was obtained.

〔Effect of the invention〕

By using the phase film-integrated transparent conductive film according to the present invention, the labor of assembling a phase plate in the STN type liquid crystal monochrome display panel assembly process can be completely eliminated.
The manufacturing process and manufacturing man-hours can be dramatically simplified and reduced.
Significant cost reductions are possible. Furthermore, it is lightweight and thin, and when used as a plastic substrate liquid crystal display element such as a flexible simple display or a curved display, the advantages of a plastic film can be utilized as is.

Claims (1)

[Claims] (1) A polysulfone film is laminated as a support layer on at least one side of a polymer transparent film phase film having birefringence and retardation set to an arbitrary value, and one surface of the laminated film is A transparent conductive film integrated with a phase film, characterized in that it is provided with a transparent conductive film.