JPH08329767A - Structure of touch panel - Google Patents

Abstract

PURPOSE: To provide a touch panel which is excellent in durability in use by preventing damage and the degradation of a touch panel surface and disruption of a movable electrode. CONSTITUTION: A surface protective single-sided pressure sensitive adhesive film 20 is separably stuck to a surface of a touch panel 10 which is arranged on a display such as a liquid crystal display and is used as an input device. Particularly, adhesive strength of the surface protective single-sided pressure sensitive adhesive film 20 to the surface of the touch panel 10 is preferable to be a width of 30 to 200g/25mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a touch panel arranged on a display such as a liquid crystal display and used as an input device.

[0002]

2. Description of the Related Art Generally, a touch panel of this type includes a movable electrode support film having a transparent movable electrode formed on one surface and a fixed electrode support plate having a transparent fixed electrode formed on one surface thereof. Spacers are separated by a slight gap, and both electrodes are superposed so as to face each other. In addition, a hard coat layer is formed on the surface (outer surface) of the movable electrode supporting film, which is hard to be damaged when touched with fingers or a pen tip (for example, Japanese Patent Laid-Open No. 5-1.
14329 publication).

In such a touch panel, the hard coat layer on the surface of the touch panel is touched with a finger or a pen tip to apply a light pressure to the movable electrode to bring it into contact with the fixed electrode to conduct electricity, thereby operating the display device. It is what makes me.

[0004]

In the above-mentioned conventional touch panel, the hard coat layer on the touch panel surface is repeatedly touched with a finger, a pen tip, or the like many times, so that the hard coat layer may be damaged by long-term use. There is a problem that the movable electrode is deteriorated, the movable electrode supporting film is also damaged or deteriorated, and the movable electrode is eventually destroyed.

The present invention is intended to solve the above problems, and to provide a touch panel excellent in use durability by preventing damage and deterioration of the touch panel surface and destruction of the movable electrode. is there.

[0006]

The above object is achieved by the structure of a touch panel in which a single-sided adhesive film for surface protection is releasably adhered to the surface of a touch panel arranged on a display and used as an input device. be able to.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a partially cutaway vertical sectional view showing an example of the structure of the touch panel of the present invention. In FIG.
Reference numeral 10 shows an example of a conventional touch panel, and 20 is a single-sided pressure-sensitive adhesive film for surface protection, which is peelably attached to the surface of the touch panel 10.

The conventional touch panel 10 has a movable electrode support film 12 having a transparent movable electrode 13 formed on one surface and a hard coat layer 11 formed on the other surface, and a transparent fixed electrode 15. The fixed electrode support plate 16 is separated from the fixed electrode support plate 16 by a small gap,
Both electrodes 13 and 15 are laminated so as to face each other.

A transparent plastic film such as a transparent polyester film is used as the movable electrode supporting film 12, and a transparent movable electrode 13 such as ITO is formed on one surface of the transparent plastic film by vapor deposition, sputtering, ion plating or the like. Various patterns are formed, and a hard coat layer 11 made of a resin such as siloxane, acryl, or epoxy is formed on the other surface. The hard coat layer 1
1 is not always necessary.

Further, as the fixed electrode support plate 16,
Usually, a transparent glass plate is used, but a transparent plastic plate or the like is also used. The fixed electrode support plate 16 has an I
Transparent fixed electrode 15 such as TO is deposited, sputtered,
Various patterns are formed by ion plating or the like.

The movable electrode support film 12 and the fixed electrode support plate 16 are fixed by an adhesive 17 applied to the peripheral edge of the electrode surface.

In the present invention, the surface protecting single-sided adhesive film 20 is releasably attached to the surface of the conventional touch panel 10 as described above. The single-sided pressure-sensitive adhesive film 20 for surface protection is obtained by coating a pressure-sensitive adhesive 22 on one surface of a base material 21 made of various transparent or translucent plastic films.

Here, as the substrate 21, a transparent polyester film having a thickness of 40 to 120 μm is particularly preferably used. When the thickness of the base material 21 made of this transparent polyester film becomes thin, the stiffness of the film becomes weak and the sticking workability deteriorates, and air bubbles easily enter during the sticking work. On the contrary, when the thickness of the base material 21 is thick, the sticking work can be performed easily, but bubbles tend to enter during the sticking work, and it becomes difficult to bring the movable electrode into contact with the fixed electrode with a light pressure.

The substrate 21 made of the transparent polyester film preferably has a haze (haze value) of 20% or less in terms of transparency. In addition, such a base material 21
A hard coat layer that is less likely to be damaged when touched with fingers or a pen tip may be formed on the surface (the surface on which the adhesive is not applied).

Further, on the pressure-sensitive adhesive coated surface of the base material 21,
The wetting index is 4 in order to increase the adhesive strength to the adhesive 22.
It is preferable that the corona discharge treatment is performed so as to be 0 dyn / cm or more. If the wetting index is less than 40 dyn / cm, adhesive residue may occur on the surface of the touch panel 10 when the surface-protecting single-sided adhesive film 20 is replaced.

As the pressure-sensitive adhesive 22, a known removable pressure-sensitive adhesive of rubber type or resin type is used, and in particular, an acrylic type pressure-sensitive adhesive is preferably used from the viewpoint of enhancing the adhesiveness to the substrate 21. For the acrylic pressure-sensitive adhesive, for example, a copolymer of acrylic acid alkyl ester and acrylic acid is used, and as the alkyl group of the acrylic acid alkyl ester,
Examples thereof include a methyl group, an ethyl group, a butyl group, a 2-ethylhexyl group, an isooctyl group, and an octyl group.

In the acrylic copolymer, the molecular weight is preferably large from the viewpoint of improving the weather resistance of the pressure-sensitive adhesive, and particularly preferably about 800,000 or more. Further, the acrylic acid component is preferably 2 to 10% by weight from the viewpoint of enhancing the adhesive strength of the adhesive.

The acrylic copolymer is preferably crosslinked to some extent in order to enhance the heat resistance of the pressure-sensitive adhesive. In order to crosslink the acrylic copolymer, a method of blending an isocyanate-based, epoxy-based, aridine-based, organometallic-based, chelate-based, amine-based or other heat-crosslinkable crosslinking agent,
Alternatively, a method of copolymerizing a diacrylate-based, triacrylate-based, divinyl-based, or other copolymerizable monomer during the production of the acrylic copolymer is adopted.

If necessary, known additives such as a tackifier, a plasticizer, a filler antioxidant, an ultraviolet absorber and the like may be added to the acrylic copolymer to improve the light transmittance and the hue. It can be blended within a range that does not impair the optical characteristics.

The adhesive 22 is preferably applied on one side of the base material 21 to a thickness of 10 to 50 μm.
More preferably, it is applied to a thickness of 0 to 40 μm.

Further, it is preferable that the thus obtained single-sided adhesive film 20 for surface protection has an adhesive force to the surface of the touch panel 10 in the range of 30 to 200 g / 25 mm width. Here, the adhesive force is a 180 degree peeling adhesive force (pulling speed 300 mm / min) measured based on JIS Z 0237.

When the adhesive strength is low, when the pressure is applied with a finger or a pen tip, the one-sided pressure-sensitive adhesive film 20 for surface protection is lifted or peeled from the end portion, so that the electrode is touched with pressure. It may interfere with signal transmission. vice versa,
When the adhesive strength is increased, the adhesive is destroyed when the surface-protecting single-sided adhesive film 20 is replaced, and the touch panel 10
Adhesive residue may be left on the surface of the product, resulting in inconvenience.

[0023]

[Function] When the surface protection single-sided adhesive film is releasably attached to the surface of the touch panel, the surface protection single-sided adhesive film is peeled and removed when it is damaged and deteriorated by the contact pressure of a finger or a pen tip. It becomes possible to replace another new single-sided adhesive film for surface protection, and the touch panel surface is always kept on a good surface without damage or deterioration.

[0024]

EXAMPLES Examples of the present invention will be shown below. Examples 1 to 8 A transparent polyester film (manufactured by Teijin Ltd.) having a thickness of 30 μm, 100 μm and 130 μm was used, and one side of this film was subjected to corona discharge treatment having a wetting index of 45 dyn / cm to obtain a substrate 21.

On one side of these base materials 21, 100 parts by weight of an acrylic copolymer (95% by weight of butyl acrylate component, 5% by weight of acrylic acid component) (manufactured by Soken Chemical Co., Ltd.) and an aromatic isocyanate (Desmodur TH ) 2 parts by weight of a toluene solution (solid content: 10% by weight) is applied, sufficiently dried at 100 ° C., a separator is attached to the pressure-sensitive adhesive layer 22 thus formed, and a paste thickness as shown in Table 1 is obtained. Eight types of surface-protecting single-sided adhesive films 20 having adhesive strength were produced.

The above-mentioned adhesive force is a 180 ° peeling adhesive force (pulling speed of 30 measured according to JIS Z 0237).
0 mm / min).

These single-sided adhesive films 20 for surface protection
Was releasably attached to the surface of the conventional touch panel 10 to form a touch panel as shown in FIG. In addition,
In the above conventional touch panel 10, the movable electrode supporting film 12 is made of a transparent polyester film, and the hard coat layer 11 is formed on the surface thereof.

With respect to the eight types of touch panels thus obtained, the workability of pasting, the workability of re-pasting,
The liquid crystal character visibility and adhesion durability were evaluated. The results are summarized in Table 1.

<Pasting workability> The separator of the one-sided pressure-sensitive adhesive film for surface protection is peeled and removed, and the one-sided pressure-sensitive adhesive film for surface protection is applied to the surface of the conventional touch panel while being pressed by hand, and there is no air bubble and the like, and it is excellent. It was evaluated whether or not it could be attached.

<Workability of re-pasting> The single-sided adhesive film for surface protection pasted on the surface of the conventional touch panel is peeled off by pulling it by hand, and then it is pasted while holding it by hand again, and can be well pasted without bubbles. It was evaluated whether or not.

<Visibility of Liquid Crystal Characters> A single-sided pressure-sensitive adhesive film for surface protection was attached to the surface of a conventional touch panel while pressing it by hand, and it was evaluated whether or not the liquid crystal characters of the liquid crystal display under the touch panel looked good without being fogged. .

<Adhesive Durability> A single-sided adhesive film for surface protection is attached to the surface of a conventional touch panel while pressing it by hand, and under normal use conditions (touching with fingers and a pen tip).
Then, it was evaluated whether or not the one-sided pressure-sensitive adhesive film for surface protection was good without floating or peeling.

[0033]

[Table 1]

In each of the above examples, Examples 1 to 4 are excellent in all performances. In Example 5, an adhesive residue was generated in the workability of re-pasting. In Example 6, the adhesion durability floated and peeling occurred. In Example 7, air bubbles were generated in the workability of pasting and the workability of re-pasting. In Example 8, the visibility of liquid crystal characters was clouded. However, the touch panels of the respective examples had the advantages and disadvantages of the present invention, although there were some differences, and were practically applicable.

[0035]

As described above, the structure of the touch panel of the present invention is characterized in that the one-sided adhesive film for surface protection is releasably attached to the surface of the touch panel which is arranged on the display and used as an input device. If this one-sided pressure-sensitive adhesive film for surface protection is damaged by touching with fingers or pen tip and deteriorates, it can be peeled off and replaced, and another new one-sided pressure-sensitive adhesive film for surface protection can be replaced. Thus, it is possible to prevent the touch panel surface from being damaged or deteriorated and the movable electrode from being broken, and to obtain a touch panel having excellent use durability.

Particularly, the adhesive strength of the single-sided adhesive film for surface protection on the surface of the touch panel is 30 to 200 g / 25.
Those with a width of mm have appropriate adhesiveness and removability,
When repeatedly touched with your fingers or pen tip, the single-sided adhesive film for surface protection does not float or peel off,
Moreover, there is an advantage that no adhesive residue is left on the surface of the touch panel when the one-sided adhesive film for surface protection is peeled off.

[Brief description of drawings]

FIG. 1 is a partially cutaway vertical sectional view showing an example of the structure of a touch panel according to the present invention.

[Explanation of symbols]

 10: Conventional touch panel 11: Hard coat layer 12: Movable electrode support film 13: Movable electrode 14: Spacer 15: Fixed electrode 16: Fixed electrode support plate 20: Single-sided adhesive film for surface protection 21: Base material 22: Adhesive

Claims (2)

[Claims] 1. A structure of a touch panel, wherein a one-sided adhesive film for surface protection is releasably adhered to the surface of a touch panel arranged on a display and used as an input device. 2. The structure of the touch panel according to claim 1, wherein the adhesive strength of the surface-protecting single-sided adhesive film on the surface of the touch panel is 30 to 200 g / 25 mm width.