JP2003114763A - Touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch panel of high quality enhanced in visibility and durability, since an electrode is prevented from being cracked and separated by pushing pressure, since warpage and a Newton ring are precluded from being generated, and since warpage, separation and foaming are not generated in an environmental test. SOLUTION: In this touch panel wherein two sheets of upper and lower electrode sheets formed with a transparent electrode on one side face of a transparent film are opposed to make transparent electrode faces directed to an inside with a prescribed space, wherein a spacer is arranged between the upper and lower electrodes, and wherein an under face of the lower electrode sheet is bonded to a transparent support plate via an adhesive layer, the adhesive layer comprises a cured rubber material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch panel used for inputting operations on a display screen.

[0002]

2. Description of the Related Art Conventionally, a touch panel has been used as a device for inputting operations on a display screen such as a CRT or LCD, and has been used as an AT for a bank.
It is used in the input operation unit of Ms, CDs, ticket vending machines, personal digital assistants, personal computers, and various industrial equipment.

Until now, the mainstream of touch panels has been a glass touch panel in which transparent electrodes are provided on a glass plate.
Recently, in order to reduce the weight and improve the impact resistance, a plastic touch panel using a plastic sheet instead of a glass plate has appeared (see JP-A Nos. 11-297160 and 2000-207123).

Generally, a touch panel has a structure in which an electrode sheet having electrodes is adhered to a supporting plate through an adhesive layer. However, when a pressing force is applied such as when inputting with a pen, the adhesive layer naturally receives the pressure. Therefore, when a soft material such as a pressure-sensitive adhesive is used for the adhesive layer, a depression due to pressure occurs, and when it is further deformed, cracking or peeling of the electrode occurs. Further, in this case, since the adhesive layers are stuck together by pressure, they easily peel off or foam during an environmental test or the like.

On the other hand, when an adhesive of thermosetting resin typified by epoxy resin or phenol resin is used as the adhesive layer, there is a difference in heat shrinkage between the electrode sheet and the transparent support plate to be adhered. In addition, since the above resin is extremely hard, distortion during bonding tends to remain, which causes Newton's rings and deteriorates the visibility of the display unit.

The present invention has been made in view of the above circumstances. It is possible to prevent the electrode from cracking or peeling due to a pressing force, to prevent warping or Newton's ring due to distortion at the time of bonding, and to avoid high temperatures such as environmental tests. It is an object of the present invention to provide a touch panel that does not warp, peel, or foam even when exposed to high humidity.

[0007]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above-mentioned object, the present inventor has found that a rubber cured product is applied to an adhesive layer for adhering a transparent film and a transparent support plate. The touch panel used can buffer the pressing force of the pen input etc. and prevent the electrode from cracking or peeling, and there is no warping or Newton's ring due to distortion during bonding, and warping, peeling, or foaming occurs during the environmental test. The present invention has been completed by finding out that it is a high-quality product that does not exist.

That is, according to the present invention, two upper and lower electrode sheets each having a transparent electrode formed on one surface of a transparent film are opposed to each other with a predetermined interval with the transparent electrode surface as an inner side, and a spacer is provided between the upper and lower electrodes. Is provided, and the lower surface of the lower electrode sheet is further adhered to the transparent support plate via an adhesive layer, and the adhesive layer is made of a rubber cured product.

The present invention will be described in more detail below. Figure 1
Shows an embodiment of the touch panel of the present invention. The upper and lower two electrode sheets 3 each having the transparent electrode 2 formed on one surface of the transparent film 1 are opposed to each other with the transparent electrode surface facing inward at a predetermined interval. A plurality of spacers 4, which are insulators, are arranged between the upper and lower electrodes in contact with the electrode surface of the lower electrode sheet, and the upper and lower electrode sheets are adhered to the outer peripheral portion of the electrode surface of the electrode sheet for insulation. An adhesive insulating layer 5 for forming the lower electrode sheet is formed on the lower surface of the lower electrode sheet, and the upper surface of the transparent support plate 6 is adhered to the lower surface of the lower electrode sheet via an adhesive layer 7 which is a cured rubber.

The adhesive layer of the present invention is a rubber cured product having rubber elasticity, and the elastic modulus of this cured product is 1 × 10 ^{4 to} 5 5.
It is preferably × 10 ⁶ Pa (1 × 10 ^{5 to} 5 × 10 ⁷ dyn / cm ² ). When the elastic modulus is in the above range, an appropriate cushioning property can be obtained at the time of pen input, the electrode can be prevented from cracking or peeling, and the panel strain can be absorbed, so that the Newton's ring does not occur. If the elastic modulus is less than 1 × 10 ⁴ Pa, dents due to pressing on the touch panel or peeling may occur during an environmental test. On the other hand, the elastic modulus is 5 × 10 ⁶ P
If it exceeds a, distortion may cause Newton's rings or warpage.

The rubber cured product can be formed, for example, by thermally curing a thermosetting rubber adhesive which gives a cured product exhibiting rubber elasticity after curing.

The thermosetting rubber-based adhesive preferably contains a polymer having a Tg (glass transition point) of 0 ° C. or lower as a base polymer. Specific examples of these polymers include, for example, olefin-based polymers such as ethylene-vinyl acetate copolymers, thermoplastic elastomers such as styrene-isoprene-styrene copolymers, synthetic rubbers such as polyisoprene and polybutadiene, polyurethane-based elastomers, Polyvinyl butyral,
Examples thereof include acrylic rubber such as (meth) acrylic acid ester copolymer, natural rubber, and silicone rubber.

Further, the thermosetting adhesive contains an organic peroxide as a curing agent for curing the adhesive by heat. As the organic peroxide, for example, one that decomposes at a temperature of 70 ° C. or higher to generate a radical can be suitably used, and further, a decomposition temperature with a half-life of 10 hours is 50 ° C. or higher, It can be selected in consideration of preparation conditions of the thermosetting adhesive, film forming temperature, curing (bonding) conditions, storage stability of the thermosetting adhesive, and the like.

Examples of usable organic peroxides include 2,5-dimethylhexane-2,5-dihydroxyperoxide; 2,5-dimethyl-2,5-di (t
-Butylperoxy) hexyne-3; di-t-butyl peroxide; t-butylcumyl peroxide; 2,
5-Dimethyl-2,5-di (t-butylperoxy) hexane; dicumyl peroxide; α, α'-bis (t
-Butylperoxyisopropyl) benzene; n-butyl-4,4-bis- (t-butylperoxy) valerate; 2,2-bis (t-butylperoxy) butane;
1,1-bis (t-butylperoxy) cyclohexane; 1,1-bis (t-butylperoxy) -3,3
5-Trimethylcyclohexane; t-butylperoxybenzoate; benzoyl peroxide; t-butylperoxyacetate; methyl ethyl ketone peroxide; t-butyl hydroperoxide; p-menthane hydroperoxide; hydroxyheptyl peroxide; chlorhexanone peroxide Octanoyl peroxide; Decanoyl peroxide; Lauroyl peroxide; Cumyl peroxide octoate; Succinic acid peroxide; Acetyl peroxide; t-Butylperoxy (2-ethylhexanoate); m-toluoyl peroxide Oxide; benzoyl peroxide; t-butyl peroxyisobutyrate; 2,4-dichlorobenzoyl peroxide, etc. Curing temperature, time, may be appropriately blended according to the physical properties that. These can be used alone or in combination of two or more.

It is recommended that the amount of the organic peroxide added is usually 0.1 to 10 parts by weight, particularly 0.2 to 2.0 parts by weight, based on 100 parts by weight of the base polymer. If the blending amount is too small, sufficient curing may not be obtained in some cases, and if the blending amount is too large, unreacted substances and by-products after curing may increase and the performance may deteriorate.

Further, as the above-mentioned thermosetting adhesive, a mixture of a cross-linking aid, a tackifier, a plasticizer, an ultraviolet absorber, an antioxidant and the like may be used if necessary.

The adhesive layer is formed so that the lower electrode sheet and the transparent support plate are adhered to each other. The method of forming the adhesive layer is not particularly limited. For example, the thermosetting adhesive is directly applied to the adhesive surface. Then, a method of sticking and curing both of them, or a method of sticking a film formed of the adhesive to the adhesive surface and curing it can be applied.

More specifically, when the thermosetting adhesive is directly applied, a solution uniformly dissolved in a solvent that does not affect the electrode sheet or the transparent support plate is applied to the adhesive surface by a known method. It is possible to employ a method in which the composition is uniformly applied, temporarily press-bonded, and then heated to bond and cure.

The adhesive layer of the present invention is preferably used as a film formed from a curable adhesive because it is easy to handle. In this case, the thermosetting adhesive can be manufactured by shooting the thermosetting adhesive with, for example, a calendar, an extruder, a press, or the like, and attaching a release sheet prepared in advance in a molten state. Also, after dissolving the thermosetting adhesive in a good solvent such as toluene, cast on a release sheet to form a film, and further laminate the release sheet on the film-formed surface, to the film on which the release sheet is attached. You can also do it.

In this case, a known release sheet can be used, for example, polyethylene terephthalate (PE
T), polyethylene (PE), polypropylene (PP)
Examples of the main material include, and PET is particularly preferable.

In the touch panel of the present invention, conventionally known members can be used as members other than the adhesive layer, such as transparent films, transparent electrodes, spacers, transparent support plates and the like.

As the transparent film, a resin film having good light transmittance, for example, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyarylate, polycarbonate, polymethylmethacrylate, triacetate, etc., having high transparency and rigidity. It is preferable to use a film made of a certain material, and the thickness thereof is usually preferably 50 to 300 μm.

On the other hand, examples of the transparent electrode include an electrode having optical transparency including ITO (indium tin oxide) and oxides of metals such as tin, indium, zinc, and cadmium, and the thickness thereof is 100. It is preferably in the form of a thin film having a thickness of up to 2000Å. The transparent sheet and the transparent electrode can be used as an electrode sheet in which the transparent electrode is formed into a thin film by sputtering or the like.

The transparent support plate may be made of the same material as the above-mentioned transparent film, glass, or the like, but the thickness thereof is 0.5 to 30 mm.
Is preferred.

The upper surface of the upper electrode sheet and the lower surface of the transparent support plate may be coated with a hard coat, an antiglare treatment, if necessary.
Antireflection treatment or the like may be performed.

The touch panel of the present invention is a CRT,
The adhesive layer may be used together with the display unit such as an LCD, for example, between the touch panel and the display unit, but the present invention is not limited to this.

[0027]

The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1] PET film (thickness 125
(μm) with an ITO electrode (thickness of 300Å) formed on the electrode sheet (70 mm × 50 mm), a sheet with an insulating spacer further arranged on the electrode surface of the electrode sheet, and an electrode sheet with the spacer arranged on the lower sheet. Then, with the electrode surface inside, the outer peripheral portions of the electrode surfaces of the upper and lower sheets were adhered and integrated with a urethane-based two-component curing adhesive.

Next, 100 parts by weight of a styrene-isoprene-styrene copolymer (D-113 Shell Chemical Co., Ltd.),
2 parts by weight of organic peroxide (Perbutyl O manufactured by NOF CORPORATION), tackifying resin (Alcon P-90 manufactured by Arakawa Chemical Co., Ltd.)
A thermosetting adhesive consisting of 10 parts by weight is formed on the lower surface of the lower electrode sheet to a thickness of 100 μm, and this is attached to a polycarbonate plate (thickness 1 mm), and the temperature is 20 ° C. at 100 ° C.
The adhesive layer was formed by heating for 30 minutes for curing and adhesion, and further, the upper surface of the upper electrode sheet was subjected to hard coating and antireflection treatment to obtain a touch panel.

The following tests were carried out using this touch panel. The results are shown in Table 1. Touch panel warpage The presence or absence of warpage of the touch panel after the adhesive layer was cured was visually confirmed. Newton 's Ring The presence or absence of Newton's ring on the touch panel after the adhesive layer was cured was visually confirmed. Sliding test 250 with φ0.8mm pen tip from the top of the touch panel
After applying a load of g and repeating the reciprocating motion in the horizontal direction,
The electrical characteristics of the film were evaluated, and those with a change in resistance of less than 10% were evaluated as good and those with a change of 10% or more were evaluated as poor. Environmental test Touch panel after curing the adhesive layer in an environment of 80 ° C
It was held for 0 hours or 500 hours in an environment of 60 ° C. and 90% RH, and the presence or absence of abnormality of the touch panel after the test was confirmed.

The elastic modulus of the adhesive layer was measured by the method shown below. The results are also shown in Table 1. Cured Material Elastic Modulus A cylindrical sample having a diameter of 25 mm and a thickness of 2 mm was measured for elastic modulus at a strain of 1% and a frequency of 1 Hz with a viscoelastic device RDS II manufactured by Rheometrics.

[Comparative Example 1] A touch panel was produced in the same manner as in Example 1 except that the adhesive layer was formed using the pressure-sensitive adhesive described below, and various tests were conducted. Pressure-sensitive adhesive: A polymer obtained by polymerizing 90 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid, and 5 parts by weight of 2-hydroxyethyl acrylate in an ethyl acetate solvent, and crosslinking the polymer with isocyanate.

[Comparative Example 2] A touch panel was prepared in the same manner as in Example 1 except that the adhesive layer was formed using an epoxy adhesive (manufactured by Excel Eposemedine Co., Ltd.), and various tests were conducted.

[0034]

[Table 1]

According to the present invention, it is possible to prevent the electrode from cracking or peeling due to a pressing force, and to prevent warping or Newton's ring due to strain during bonding, and to prevent warping, peeling or foaming during an environmental test. Therefore, a touch panel with high visibility and durability and high quality can be provided.

[0035]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a touch panel of the present invention.

[Explanation of symbols]

1 transparent film 2 transparent electrode 3 electrode sheet 4 spacers 5 Adhesive insulation layer 6 Transparent support plate 7 Adhesive layer

Claims (3)

[Claims] 1. An upper and lower electrode sheet having a transparent electrode formed on one surface of a transparent film are opposed to each other with a predetermined interval with the transparent electrode surface as an inner side, and a spacer is disposed between the upper and lower electrodes. A touch panel in which the lower surface of the lower electrode sheet is further adhered to a transparent support plate via an adhesive layer, and the adhesive layer is made of a rubber cured product. 2. The elastic modulus of the rubber cured product is 1 × 10 ^{4 to} 5 ×.
The touch panel according to claim 1, wherein the touch panel has a pressure of 10 ⁶ Pa. 3. The cured rubber product is a cured product of a thermosetting rubber adhesive.
The touch panel described.