JP2000149664A - Protective structure of transparent conductive layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it difficult to generate malfunctions even in outdoor operation, and to enable formation of a high resolution type touch panel. SOLUTION: This protective structure has protection layers 1, 2, 3, 11 composed of two or more layers on one side of a transparent conductive layer 4. The layers 1, 2, 3, 11 decrease a transmittance of ultraviolet ray of wavelength 310-340 nm to a level of not more than 10% while maintaining a transmittance of visible light of wavelength 410-700 nm to a level of not less than 70%. Accordingly, the resistance of the transparent conductive layer 4 is hard to change under a condition of incidence of sunlight in the case of an outdoor operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective structure for a transparent conductive layer having excellent light resistance and suitable for an electrode plate of a mobile touch panel.

[0002]

BACKGROUND OF THE INVENTION With the widespread use of touch panels in mobile applications and the like, the chances of using the touch panels outdoors have increased and unexpected display functions have been reduced. That is, a touch panel is usually such that a transparent conductive layer is arranged opposite to a spacer, and a contact position is detected by measuring a contact current by measuring a current flowing through one side in the contact operation of the other through a pressing operation. However, there is a trouble that causes a malfunction or the like in the position detection.

[0003] Malfunctions are particularly noticeable in high-resolution touch panels that enable input of kanji characters and the like, and in view of the possibility of sunlight incident for outdoor use, ultraviolet-cut touch panels have been proposed. However, even in the case of such an ultraviolet cut type, a malfunction occurs, and at present, it is not a sufficient countermeasure.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to form a high-resolution touch panel which is unlikely to malfunction even when used outdoors.

[0005]

According to the present invention, one side of a transparent conductive layer is provided.
Or, it is composed of two or more layers and has a wavelength of 410 to 700 nm.
While maintaining a transmittance of 70% or more for visible light,
An object of the present invention is to provide a protective structure for a transparent conductive layer, which has a protective layer for reducing the transmittance of ultraviolet rays having a wavelength of 310 to 340 nm to 10% or less.

[0006]

According to the present invention, it is possible to form a touch panel in which the resistance value of the transparent conductive layer hardly changes even under sunlight incident from outdoor use, and which does not easily malfunction even in a high-resolution type. it can. This is due to the absorption of the above-mentioned ultraviolet light in the specific wavelength range and the prevention of such ultraviolet light from entering the transparent conductive layer.

That is, the inventors of the present invention have conducted intensive studies to overcome the above-mentioned problems, and have conducted irradiation with an ultraviolet lamp with a hint that the resistance value of the transparent conductive layer slightly fluctuated under sunlight. When they tried, they showed a remarkable fluctuation that the resistance value decreased, and found that the fluctuation of the resistance value could be prevented by cutting off the ultraviolet rays.

However, as described above, a malfunction occurs in the conventional ultraviolet-cut type touch panel, and the wavelength characteristics of the ultraviolet light are examined in consideration of the malfunction. As a result, it is found that the ultraviolet light in a specific wavelength range greatly affects the fluctuation of the resistance value. The present inventors have sought and found that the protective structure according to the present invention as described above prevents the resistance value of the transparent conductive layer from fluctuating and achieves the above-described effects.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The protective structure according to the present invention comprises one or more layers on one side of a transparent conductive layer and a wavelength of 4 or more.
It has a protective layer that reduces the transmittance of visible light of 10 to 700 nm to 70% or more and the transmittance of ultraviolet light of wavelength 310 to 340 nm to 10% or less to protect the transparent conductive layer. is there. An example is shown in FIG. 4
Is a transparent conductive layer, 1 and 3 are transparent substrates, 11 is a coat layer, and 2 is an adhesive layer.

[0010] In the present invention, the transparent conductive layer to be protected is not particularly limited, and may be an appropriate one such as a conventional one. Incidentally, examples thereof include metal oxides such as indium oxide and tin oxide, titanium oxide and cadmium oxide, and mixtures of such metal oxides such as ITO, for example, by vacuum evaporation, sputtering, ion plating, spray pyrolysis, and the like. And a layer formed by forming a thin film by an appropriate method such as a chemical plating method, a chemical plating method, an electroplating method, or a combination thereof.

Although the thickness of the transparent conductive layer is arbitrary, it may be formed into a thin film of about 30 ° which is difficult to handle by itself, for example, for an electrode for a touch panel. Therefore, the transparent conductive layer 4 is provided on the transparent base material 3 as necessary, as shown in the example of the drawing. In the present invention, the transparent base material 3 supporting the transparent conductive layer 4 can be used as a protective layer if necessary.

The transparent substrate is not particularly limited, and an appropriate one can be used. By the way, as examples, polyester resins and acetate resins, polyether sulfone resins and polycarbonate resins, polyamide resins and polyimide resins, polyolefin resins and acrylic resins, polyvinyl chloride resins and polystyrene resins, Examples thereof include polymers such as polyolefin resins, polyvinyl alcohol resins, polyarylate resins, polyphenylene sulfide resins, polyvinylidene chloride resins, and (meth) acrylic resins.

Above all, a transparent substrate which can be preferably used as a protective layer is one which absorbs ultraviolet rays and has excellent transmittance to visible light, such as a polyester made of polyester which absorbs ultraviolet rays having a wavelength of 300 nm or less.

The thickness of the transparent substrate is generally from 3 to 500 μm, preferably from 5 to 300 μm, and especially from 10 to 200 μm, but is not limited to this, and may be an appropriate thickness depending on the purpose of use. it can. When attaching the transparent conductive layer,
The surface of the transparent substrate may be subjected to an appropriate pretreatment such as a corona discharge treatment, an ultraviolet irradiation treatment, a plasma treatment, a sputter etching treatment, an undercoat treatment, etc., to enhance the adhesion to the transparent conductive layer.

The protective structure according to the present invention can be formed as one or more layers on one side of the transparent conductive layer, including the transparent substrate supporting the transparent conductive layer. The point provided on one side of the transparent conductive layer is because it is necessary to have a predetermined ultraviolet content or the like before incident ultraviolet light based on sunlight or the like reaches the transparent conductive layer.

The protective layer can be provided in an appropriate layer form such as the above transparent substrate or a coat layer attached thereto, and an ultraviolet absorber can be used as needed for the formation of the protective layer. . Further, the ultraviolet absorber can be used in a suitable manner as a method of mixing into a transparent substrate, an adhesive layer or a coat layer, or a coat layer composed of the ultraviolet absorber itself.

Accordingly, in the layer configuration of the touch panel as shown in the figure, the transparent substrate 3 supporting the transparent conductive layer 4, the transparent substrate 1 serving as a support base of the entire panel, and the hard coat provided on the surface thereof as necessary Some or all of the adhesive layer 2 for bonding the transparent substrate 1 and the transparent substrate 3 can be used as a protective layer.

In the case where the protective layer is formed as a mixed layer of an ultraviolet absorber in the above description, the protective layer is formed at a temperature of 60.degree.
It is preferable that the mixed ultraviolet absorber does not bleed out for at least 700 hours, especially at least 700 hours, especially at least 1000 hours. Bleed-out of the ultraviolet absorbent tends to cause a decrease in the protective function, transparency due to cloudiness or haze, and particularly a decrease in visible light transmittance. Bleed-out may occur due to heat treatment when a transparent conductive layer is provided on a transparent substrate.

The protective structure according to the present invention is based on one or two or more protective layers provided on one side of the above-mentioned transparent conductive layer.
%, Especially 75% or more, particularly 80% or more, while maintaining the transmittance for ultraviolet rays having a wavelength of 310 to 340 nm as 1%.
The transmittance is reduced to 0% or less, particularly 5% or less, particularly 2% or less. Thereby, while achieving a good display color, especially a color display color, etc. in the case of a touch panel or the like, a change in the resistance value of the transparent conductive layer due to the incidence of sunlight or the like, particularly, a malfunction due to a decrease in the resistance value is prevented. be able to. It is preferable to suppress the rate of change of the resistance value to 5% or less from the viewpoint of preventing malfunction.

The protective layer, which is particularly preferable from the viewpoint of preventing the resistance value of the transparent conductive layer from fluctuating, has a wavelength of 300 to 350 nm, preferably 3 to 3 nm.
30% to 340nm, especially 340nm UV transmittance 5%
Hereinafter, it is 2% or less, especially 1% or less. Further, the protective layer, which is preferable from the viewpoint of preventing coloration or color change, particularly good color balance by preventing yellowing, and the like, has a transmittance of light having a wavelength of 400 nm of 60% or more, particularly 75% or more, particularly 80% or more. And a transmittance of visible light having a wavelength of 410 to 700 nm of 75% or more, particularly 80% or more.

In the above, one kind or two or more kinds of appropriate ultraviolet absorbers can be used. A wavelength of 340 nm or less, especially 350 nm
Those which are excellent in the ability to absorb ultraviolet light having a wavelength of 400 nm or less and have a minimum absorption of visible light having a wavelength of 400 nm or more are preferably used.

Ultraviolet absorbers that can be preferably used from the viewpoint of the protective function by transmitting and absorbing light of each wavelength and preventing bleed-out are inorganic ultraviolet absorbers, reactive ultraviolet absorbers, and those having a molecular weight of 1,000 or more. And high molecular weight ultraviolet absorbers. The above-mentioned inorganic ultraviolet absorber can be preferably used for mixing and the like, and examples thereof include titanium oxide.

The reactive ultraviolet absorber can be compounded through a functional group and is excellent in bleed-out prevention and the like, and can be preferably used for mixing and forming a coat layer.
Examples thereof include RUVA-93 (manufactured by Otsuka Chemical Co., Ltd.).

Further, a high molecular weight ultraviolet absorber can also be preferably used for mixing or forming a coat layer, for example, such as PUVA93 (molecular weight 10,000) and UV
A-933LH (manufactured by BASF, molecular weight 250,000) and the like. According to a high molecular weight ultraviolet absorber which can be cross-linked by heat treatment or the like, it is possible to form a hard coat layer which also serves as an ultraviolet absorber and is used for preventing damage.

As the transparent base material which can also serve as the support base of the touch panel and the like, which can also serve as the above-mentioned protective layer, an appropriate material such as the one exemplified as the above-mentioned material with a transparent conductive layer can be used. Also as an adhesive layer that can also serve as a protective layer,
An appropriate material having transparency can be used. Above all, for example, acrylic adhesive, silicone adhesive, rubber adhesive,
Alternatively, an appropriate pressure-sensitive adhesive such as various thermoplastic films, a hot-melt adhesive, or the like can be preferably used from the viewpoint of easy adhesion.

On the other hand, as a hard coat other than the above-mentioned high-molecular-weight ultraviolet absorber which is provided on a transparent substrate or the like and can also serve as a protective layer, for example, an appropriate hard coat such as an acrylic urethane resin or a siloxane resin is used. Examples thereof include a resin that has been applied and cured. In that case, the protection function according to the present invention can be achieved by, for example, a method of mixing an ultraviolet absorber.

On the other hand, the anti-glare layer provided for the purpose of preventing visual obstruction due to external light reflection on the surface has a fine uneven structure on the surface by various methods such as a sand blast method, an embossing method, and a method of mixing fine particles. In this case, the surface may be provided as a sheet having a finely uneven structure. The surface of the hard coat layer may be roughened to form a hard coat layer also serving as an anti-glare layer. The protective function of the antiglare layer according to the present invention can be achieved according to the above-mentioned hard coat layer.

The protective structure according to the present invention can be preferably applied to various devices using a transparent conductive layer, such as a touch panel and a liquid crystal display.

[0029]

EXAMPLE 1 A 5 μm thick hard coat layer made of an acrylic urethane resin was provided on one surface of a polyester film having a thickness of 125 μm, and an ultraviolet absorber (UVA9 manufactured by Otsuka Chemical Co., Ltd.) was provided on the other surface.
A conductive film having an ITO vapor-deposited film on one side of a 23 μm-thick polyester film is adhered and laminated via the polyester film surface via a 25 μm-thick acrylic adhesive layer containing 2% by weight of 3) to form a transparent conductive film. A touch panel having a layer protection structure was obtained. FIG. 2 shows the light absorption characteristics of the adhesive layer.

When the touch panel was exposed to sunlight, no change was observed in the resistance value of the transparent conductive layer, and the intensity of 15 mw / cm ^{2 was} measured with an ultraviolet lamp (Ushio Electric Co., Ltd., Handicure 100). For 20 minutes (the same applies hereinafter), no change was observed in the resistance value of the transparent conductive layer.
Further, a moisture and heat resistance test (left for 1000 hours in an atmosphere of 60 ° C. and 95% RH, the same applies hereinafter) and a heat resistance test (90 ° C.
, And no change in optical characteristics was observed.

Example 2 High molecular weight ultraviolet absorber (PUVA93, molecular weight 10,000) 1
1 in which 1.5 parts of an isocyanate-based crosslinking agent was blended with
A 2% by weight toluene solution was applied to one side of a polyester film having a thickness of 125 μm and heat-treated at 150 ° C. for 10 minutes to form a protective hard coat layer having a thickness of 2.5 μm. A conductive film according to Example 1 was bonded and laminated via the polyester film surface via an acrylic adhesive layer to obtain a touch panel having a transparent conductive layer protective structure. FIG. 2 shows the light absorption characteristics of the hard coat layer.

When the above touch panel was exposed to sunlight, no change was observed in the resistance value of the transparent conductive layer, and no change was observed in the resistance value of the transparent conductive layer even under irradiation with an ultraviolet lamp. Further, in the heat-and-moisture resistance test and the heat resistance test, no bleed-out or other change in optical characteristics was observed.

Example 3 An 80 μm-thick triacetylcellulose film (TD-80U, manufactured by Fuji Film Co., Ltd.) containing an ultraviolet absorber.
Then, a conductive film according to Example 1 was bonded and laminated via an acrylic adhesive layer having a thickness of 25 μm via the polyester film surface thereof to obtain a touch panel having a protective structure of a transparent conductive layer. FIG. 2 shows the light absorption characteristics of the triacetyl cellulose film.

When the above touch panel was exposed to sunlight, no change was observed in the resistance value of the transparent conductive layer, and no change was observed in the resistance value of the transparent conductive layer even under irradiation with an ultraviolet lamp. Further, in the heat-and-moisture resistance test and the heat resistance test, no bleed-out or other change in optical characteristics was observed.

Example 4 A touch panel was obtained in the same manner as in Example 1 except that the adhesive was laminated via an acrylic adhesive layer containing no ultraviolet absorber.
FIG. 2 shows the light absorption characteristics of the adhesive layer. When this touch panel was exposed to sunlight, the resistance value of the transparent conductive layer was reduced by 15%, and it could not be used as a touch panel.

Example 5 As an ultraviolet absorber, tinuvin 32 was used instead of UVA93.
7 (manufactured by Ciba-Geigy) was adhered and laminated via an acrylic adhesive layer containing 1% by weight, and a touch panel was obtained in the same manner as in Example 1. In addition, as shown in FIG.
It exhibited light absorption characteristics in which the transmittance exceeded 20% in the vicinity of light having a wavelength of 340 nm. When this touch panel was exposed to sunlight, the resistance value of the transparent conductive layer was reduced by 10%, and the touch panel could not be used as a touch panel.

Example 6 Example 5 was repeated except that the amount of tinuvin 327 was changed to 4% by weight.
A touch panel was obtained according to As shown in FIG. 2, the adhesive layer has a transmittance of about 0.5 at a wavelength of 340 nm.
%. Although the resistance value of the transparent conductive layer did not change when the touch panel was exposed to sunlight, the ultraviolet absorber (tinuvin) was bleached out after 500 hours of the moist heat resistance test, and peeled off from the adhesive end face by the adhesive layer. And a whitened portion was observed inside the touch panel surface.

Example 7 A touch panel was prepared in the same manner as in Example 1 except that the adhesive was laminated via an acrylic adhesive layer containing 2% by weight of ADK STAB LA31 (manufactured by Asahi Denka Co., Ltd., molecular weight: 659) instead of UVA93 as an ultraviolet absorber. I got FIG. 2 shows the light absorption characteristics of the adhesive layer. In addition, this touch panel had no change in the resistance value of the transparent conductive layer even when exposed to sunlight and an ultraviolet lamp, but the ultraviolet absorber (ADK STAB LA31) was bleached out after 500 hours of the moist heat test,
The precipitated crystallized substance was observed inside the touch panel surface.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a graph showing light absorption characteristics.

[Explanation of symbols]

 1,3: transparent base material (11: coat layer) 2: adhesive layer 4: transparent conductive layer

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Kyoya Oyabu 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 5G307 FA02 FB01 FC09 FC10 5G435 AA00 AA14 EE33 GG16 HH02 HH12 KK07

Claims (7)

[Claims] 1. One side of a transparent conductive layer is composed of one or more layers, and maintains a transmittance of 70% or more with respect to visible light having a wavelength of 410 to 700 nm while maintaining a transmittance of at least 70%.
A protective structure for a transparent conductive layer, comprising a protective layer that reduces the transmittance of ultraviolet light of 40 nm to 10% or less. 2. The protective structure according to claim 1, wherein the protective layer comprises one or more layers of a mixed layer or a coat layer of an ultraviolet absorbent. 3. The protective structure according to claim 2, wherein the protective layer containing the ultraviolet absorbent does not bleed out the ultraviolet absorbent for 500 hours or more in an atmosphere of 60 ° C. and 95% RH. 4. The protective structure according to claim 2, wherein the ultraviolet absorber comprises a reactive ultraviolet absorber, an inorganic ultraviolet absorber, or a high molecular weight ultraviolet absorber having a molecular weight of 1,000 or more. 5. The method according to claim 2, wherein the mixed layer is an adhesive layer or a transparent substrate containing an ultraviolet absorbent, or the coat layer is a layer provided with a transparent substrate, and the adhesive layer or the transparent substrate is a touch panel. The protective structure that is to be formed. 6. The protective layer according to claim 1, wherein the protective layer has a transmittance of 5% or less for ultraviolet rays having a wavelength of 300 to 350 nm, a transmittance of 60% or more for light having a wavelength of 400 nm, and a transmittance of 410 to 700 nm. A protective structure having a visible light transmittance of 75% or more. 7. The protective structure according to claim 5, wherein the transparent conductive layer is made of ITO, and the transparent substrate is made of polyester.