JPH04124601A - Polarizing plate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a polarizing film-based polarizing plate having a transparent conductive layer and having excellent shielding properties against static electricity and electromagnetic waves.

BACKGROUND ART Polarizing plates made of polarizing films have been in widespread use for a long time and have been put to practical use in various fields such as liquid crystal display devices for instruments, electronic watches, office automation equipment, desktop electronic computers, and the like. When attaching a polarizing plate to a liquid crystal display device or the like, an adhesive layer is provided, but the adhesive layer is usually covered and protected with a separator or the like until it is used for adhesion. On the other hand, in the assembly process of a liquid crystal display device or the like or the distribution process of a polarizing plate, a protective film is provided on the surface of the polarizing plate, thereby protecting the surface of the polarizing plate.

Conventionally, as the polarizing plate used in the above manner, there have been known those made of a polarizing film itself, and those provided with a transparent protective layer made of a resin film on one or both sides of the polarizing plate.

However, there is a problem in that dust and the like adhere to the polarizing plate between the time when the separator and the like are peeled off and removed from the adhesive layer attached to the polarizing plate and the polarizing plate is used for adhesion, causing contamination and causing poor appearance. On the other hand, if the surface protective film is peeled off and removed after the polarizing plate is adhered to the liquid crystal display device via the adhesive layer, an abnormal display occurs and a normal liquid crystal display cannot be realized. Furthermore, there is also the problem that the liquid crystal display device malfunctions during operation.

Means for Solving the Problems The present inventors have conducted intensive research to overcome the above-mentioned problems, and have found that the above-mentioned problems of contamination of the adhesive layer, problems of abnormal display of liquid crystals, and problems of malfunction of liquid crystal display devices have been solved by using separators, We discovered that the main causes are static electricity when removing the surface protection film and electromagnetic noise from the outside world, and based on this knowledge, we developed a polarizing plate that can deal with static electricity and electromagnetic waves without damaging the optical properties of the polarizing film. Further research was conducted to develop this, and by adding a transparent conductive layer, the above objectives were successfully achieved, resulting in the present invention.

That is, the present invention provides a polarizing plate characterized by providing a transparent conductive layer on one or both sides of a polarizing film.

By providing a transparent conductive layer on one or both sides of the polarizing film, it is possible to shield static electricity and electromagnetic waves, eliminating the problem of contamination of the adhesive layer due to the adhesion of dust due to static electricity, and the problem of abnormal display of liquid crystals due to disordered liquid crystal alignment. can do. Further, the problem of malfunction of the liquid crystal display device due to electromagnetic wave noise can also be solved.

EXAMPLE FIG. 1, FIG. 2, FIG. 3, and FIG. 4 illustrate the polarizing plate of the present invention. 2 is a transparent conductive layer, and 5 is a polarizing film. In addition, 1 is a surface protection film, 3 is a transparent protective layer, 4 is a moisture-proof layer, 6 is an adhesive layer, and 7 is a separator.

In the case shown in FIG. 1, a transparent conductive layer 2 is formed on one side of a transparent plastic film for forming a transparent protective layer 3.
A moisture-proof layer 4 is formed on the other side, and this is adhered to both sides of the polarizing film 5 with a transparent adhesive so that each moisture-proof layer 4 is on the inside.

In the case shown in FIG. 2 or 3, a transparent plastic film (transparent protective layer 3) is adhered to both sides of a polarizing film 5 via a transparent adhesive, and either one side (FIG. 2) or both sides ( A second transparent protective layer 3 is provided by adhering the above-mentioned transparent plastic film provided with the transparent conductive layer 2 and the moisture-proof layer 4 to the transparent conductive layer 2 (FIG. 3) via a transparent adhesive. In the polarizing plate shown in FIG. 3, the upper transparent conductive layer 2 is disposed between the first and second transparent protective layers 3.

In the case shown in Fig. 4, a transparent plastic film (transparent protective layer 3) is bonded to both sides of a polarizing film 5 via a transparent adhesive, and a transparent conductive layer 2 and a moisture-proof layer are attached to one side via a transparent adhesive. A second transparent protective layer 3 is provided by adhering transparent plastic films having layers 4 in a superimposed state.

There are no particular limitations on the polarizing film (5) used in the present invention. Generally, a polarizing film is made by adsorbing iodine and/or dichroic dye to a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or a partially saponified ethylene-vinyl acetate copolymer film. Alternatively, a polarizing film made of an oriented polyene film such as a dehydrated polyvinyl alcohol or a dehydrochlorinated polyvinyl chloride film may be used. Although the thickness of the polarizing film is not limited, it is usually 5 to 80 μI.

The polarizing film used may have a transparent protective layer (3) on one side or both sides, if necessary. A transparent protective layer may not be necessary for a polarizing film having sufficient strength, such as an oriented polyene polarizing film. In addition, two or more transparent protective layers may be provided on one side or both sides of the polarizing film, as is clear from the examples described above.

As the material for forming the transparent protective layer, those having excellent optical transparency, heat resistance or thermal stability, and moisture resistance or moisture shielding properties are preferably used. Typical examples include polymers such as polyester resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, acrylic resins, and acetate resins. When forming the transparent protective layer, the polymer can be applied by coating, but it is preferable to form the polymer into a film in advance and apply it from the viewpoint of obtaining a polarizing plate with stable quality. In the case of applying it as a film, there is an advantage that it can be used as a base for attaching a transparent conductive layer, etc., as in the above embodiment. The thickness of the transparent protective layer is 10~500μ steel, especially 5
The time is typically 0 to 300 us, but is not limited thereto.

The polarizing plate of the present invention includes one or more transparent conductive layers (
2) is provided. The transparent conductive layer may be provided at any position such as the outer surface of the polarizing film, the outer surface of the transparent protective layer, the interface between the transparent protective layers, the interface between the polarizing film or the transparent protective layer and the adhesive layer, etc. .

As the material for forming the transparent conductive layer, materials with excellent optical transparency are preferably used. Typical examples include tin oxide, indium oxide, cadmium oxide, titanium oxide, metallic indium, metallic tin, gold, silver, platinum, palladium,
Examples include copper, aluminum, nickel, chromium, titanium, iron, cobalt, copper iodide, and mixtures and alloys thereof.

The thickness of the transparent conductive layer may be determined as appropriate depending on the intended use. In general, the thickness is preferably 80 to 5,000 when forming a transparent conductive layer with an oxide or a mixture thereof, and 50 to 400 when forming a transparent conductive layer with metal (including alloys). . If the thickness is too thin, the shielding performance against static electricity and electromagnetic waves tends to deteriorate due to defects in the film structure, and if it is too thick, the visible light transmittance decreases, which is undesirable.

The surface resistance of the transparent conductive layer is 109Ω/'4 or less for electrostatic shielding, and 1 for electromagnetic shielding.
It is preferable that it is 0.3Ω/- or less.

The transparent conductive layer can be formed using, for example, a vacuum evaporation method, a sputtering method, an ion blating method, a chemical vapor deposition method,
This can be easily carried out by applying a thin layer forming method such as a spray pyrolysis method, a chemical plating method, an electroplating method, or a suitable combination thereof.

The polarizing plate of the present invention is provided with one or more moisture-proof layers (4) as required. Adding a moisture barrier layer is effective in blocking moisture and preventing deterioration of the polarizing film due to the synergistic effect of heat and humidity, which causes deterioration of polarizing properties and decolorization. A more excellent polarizing plate can be obtained, and it can be preferably applied to liquid crystal display devices mounted on automobiles. Therefore, for example, in a polarizing film having sufficient water resistance such as an oriented polyene polarizing film, a moisture-proof layer may not be necessary.

Note that the moisture-proof layer is preferably provided on the outside side of the polarizing film.

As the material for forming the moisture-proof layer, those having excellent optical transparency, heat resistance, and thermal stability are preferably used. Typical examples include silicon oxide, indium oxide, tin oxide,
Metal compounds such as titanium oxide, aluminum oxide, zirconium oxide, magnesium fluoride, and zinc sulfide, fluorine-based polymers such as polytetrafluoroethylene and polychlorotrifluoroethylene, acrylic polymers, urethane polymers,
Examples include polymers such as vinyl chloride polymers and rubber polymers.

The moisture-proof layer can be formed, for example, by an appropriate thin layer formation method such as a coating method or a vacuum deposition method.

The thinner the material is, the more preferable it is in view of the viewing angle when used as a liquid crystal display device or the like. The desirable thickness of the moisture-proof layer is 100 to 5,000 in the case of a metal compound, especially 200 to 2,000 in the case of a fluorine-based polymer, and 0.1 to 5-1 in the case of a fluorine-based polymer. In the case of polymers, rubber-based polymers, etc., it is 10 to 20 On. From the point of view of forming a thin moisture-proof layer or a polarizing plate, vacuum deposition method,
It is preferable to apply a moisture-proof layer using a sputtering method, an ion blating method, or the like. Such a method is moisture-proof,
It also has the advantage of being able to form a moisture-proof layer with excellent transparency and adhesion to the base film. Note that the moisture-proof layer can also serve as a water-blocking transparent conductive layer made of, for example, tin oxide, indium oxide, titanium oxide, or the like.

Surface protection film (1) attached to the polarizing plate as necessary
An appropriate film may be used. In general, materials with good adhesion to the polarizing plate, peelability, stain resistance, workability, weather resistance, etc. are used. Especially polyethylene and ethylene.
A two-layer extrusion film with a vinyl acetate copolymer is preferably used.

Further, an adhesive having good adhesiveness, workability, durability, etc. is preferably used to form the adhesive layer (6) attached to the polarizing plate if necessary. Among these, acrylic pressure-sensitive adhesives are preferably used. The thickness of the attached adhesive layer is 2 or more layers, especially 5
~500 μs is typical.

On the other hand, a separator etc. for covering and protecting the adhesive layer (7)
As such, those having good removability, workability, etc. are preferably used. Among these, a separator formed by treating a polyester film with a silicone release agent is preferably used.

The polarizing plate of the present invention may have ultraviolet absorbing ability by treating its polarizing film, transparent conductive layer, transparent protective layer, moisture-proof layer, adhesive layer, etc. with an ultraviolet absorber.

As the ultraviolet absorber, appropriate ones may be used, such as salicylic acid ester compounds, hensifenol compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex salt compounds.

Example 1 A 30μ thick iodine/polyvinyl alcohol polarizing film was coated with an 80μ thick acrylic adhesive on both sides.
A polarizing plate was obtained by adhering a triacetyl cellulose film (first transparent protective layer) with a thickness of 75 cm and a polyester film (second transparent protective layer) with a thickness of 75 mm to one side of the film through an acrylic adhesive. . This polarizing plate consists of a transparent conductive layer based on a 120-meter thick silver layer attached in advance by vacuum deposition on one side of the polyester film forming the second transparent protective layer, and a transparent conductive layer based on a 120-meter thick silver layer attached on the other side in accordance with the above-mentioned thickness. It has a moisture barrier layer based on 2000 silicon oxide layers. Note that the transparent conductive layer side was arranged so as to be on the triacetyl cellulose film side of the first transparent protective layer.

Example 2 A transparent conductive layer that also served as a moisture barrier layer was formed on one side of a polyester film by a sputtering method, consisting of a composite layer of indium oxide and tin oxide (M ratio: In2O3/SnO2: 9/1) with a thickness of approximately 600 mm. A polarizing plate was obtained according to Example 1, except that this was used as a second transparent protective layer and the transparent conductive layer side was arranged so that the triacetylcellulose film side was the same.

Comparative Example A polarizing plate was obtained in the same manner as in Example 1, except that the polyester film as the second transparent protective layer was not provided.

Therefore, this product does not have a transparent conductive layer and a moisture barrier layer.

A surface protection film made of a two-layer extruded polyethylene/ethylene/vinyl acetate copolymer film was pasted on the outer surface of the bond on which the transparent conductive layer was arranged in the polarizing plates obtained in the evaluation test examples and comparative examples. An acrylic adhesive layer with a thickness of 20 nm was attached to the other side, and the surface was covered and protected with a separator made of a polyester film treated with a silicone release agent, and the sample was subjected to the following test.

[Static electricity shielding property] The amount of static electricity on the surface of the polarizing plate after peeling and removing the separator and surface protection film was measured using a current collecting potential measuring device (part name: KS-471 type, manufactured by Kasuga Denki Co., Ltd.). .

We also investigated the amount of dust adhering to the adhesive layer after the separator was peeled off and the abnormal display of the liquid crystal after the surface protection film was peeled off and adhered to the liquid crystal display device via the adhesive layer.

[Electromagnetic shielding] Electromagnetic shielding effect measuring device (product name: TR-1730)
1, manufactured by Atopan Test Co., Ltd.), the electric field shielding effect was measured at a frequency to 'H7% of 108 or 1097 in the polarizing plate after peeling off the layer and the surface protection film.

Furthermore, the frequency of malfunctions in the presence of electromagnetic waves was investigated by adhering it to a liquid crystal display device via an adhesive layer.

[High temperature and high humidity resistance] A polarizing plate is bonded to a glass plate through its adhesive layer and heated to 60°C.
Single transmittance T1 of visible light (wavelength: 550 nm) for those left in an atmosphere of 95% R, H for 500 hours
Find parallel transmittance Tp x orthogonal transmittance Th, and from this,
Based on the following formula, change amount ΔT of single transmittance T and degree of polarization P
The amount of change ΔP was calculated.

Note that the parallel transmittance Tp is the light transmittance when the light absorption axes of the two polarizing plates are aligned in parallel, and the orthogonal transmittance Th is the light transmittance when the light absorption axes of the two polarizing plates are aligned at right angles. is the light transmittance of

ΔT=TI−T.

ΔP=P -p.

however, TOL PO is the value before the test, Pl is trial This is the value after the experiment.

The results are shown in the table.

In addition, the polarizing plate of the example in which a moisture-proof layer was added maintains good polarization properties even when placed in a high temperature and high humidity atmosphere.
The polarizing film was resistant to decolorization, had excellent high temperature and high humidity resistance, and had excellent humidification durability.

Effects of the Invention According to the polarizing plate of the present invention, since a transparent conductive layer is provided, static electricity and electromagnetic waves can be shielded, and contamination of the adhesive layer due to static electricity and abnormal display of the liquid crystal can be prevented.
Malfunctions of the liquid crystal display device due to electromagnetic waves can be prevented.

[Brief explanation of drawings]

Figure 1, Figure 2, Figure 3, FIG. 1.Surface protection film 3: Transparent protective layer 5: Polarizing film 7: Separator 2: Transparent conductive layer 4; Moisture barrier layer 6 Adhesive layer Figure 4 shows each other. Patent applicant: B-Taku Electric Works Co., Ltd. Representative Fuji Fuji Hon Tsutsutsutsu Bu figure Third figure No. figure No. Book figure

Claims (1)

[Claims] 1. A polarizing plate characterized by providing a transparent conductive layer on one or both sides of a polarizing film.