JP2667686B2 - Transparent conductive laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a transparent conductive laminate in which a transparent conductive thin film is provided on one surface of a film substrate and a transparent substrate is bonded on the other surface. About.

[Conventional technology]

In general, thin films that are transparent in the visible light region and have electrical conductivity are used in new displays such as liquid crystal displays and electroluminescence displays, as well as in transparent electrodes in touch panels, etc. Used for

Conventionally, as such a transparent conductive thin film, a so-called conductive glass in which an indium oxide thin film is formed on glass is well known. However, since the base material is glass, flexibility and workability are poor. However, it may not be preferable depending on the use.

For this reason, in recent years, in addition to flexibility and workability, it has excellent impact resistance and is lightweight, so that it has advantages such as polyethylene terephthalate film and various kinds of plastic films as base materials. Has been awarded.

[Problems to be solved by the invention]

However, the conventional transparent conductive thin film using such a film substrate has poor scratch resistance on the surface of the thin film, and has a problem that when the film is scratched during use, the electric resistance increases or the wire breaks. Was.

In particular, in the case of a conductive thin film for a touch panel, a pair of thin films opposed to each other via a spacer come into strong contact at a pressing point from one of the base material sides. It is desired to have characteristics, that is, hitting characteristics. However, the above-mentioned conventional transparent conductive thin film is inferior in such characteristics, and there is a problem that the life of the touch panel is shortened.

Further, in this type of conventional transparent conductive thin film, since the film base surface on the side opposite to the surface on which the conductive thin film is formed is in a bare state, surface scratches are likely to occur during use, which causes There is a disadvantage that the visibility of the whole thin film product is apt to decrease.

An object of the present invention is to improve the scratch resistance, hitting point characteristics, and visibility of a transparent conductive thin film using a film substrate such as a polyethylene terephthalate film in view of the above conventional problems.

[Means for solving the problem]

As a result of intensive studies to achieve the above object, the present inventors have used a film substrate having a specific film thickness to form a transparent conductive thin film on one surface thereof, while forming a transparent conductive thin film on the other surface thereof. By bonding another transparent substrate that has been subjected to a specific treatment through a transparent pressure-sensitive adhesive layer, the abrasion resistance and hitting point characteristics of the thin film surface are improved, and the decrease in visibility due to the occurrence of surface flaws is greatly increased. We knew that it could be suppressed, and completed this invention.

That is, according to the present invention, a transparent conductive thin film having a thickness of 50 ° or more is formed on one surface of a transparent film substrate having a thickness of 2 to 120 μm, and an elastic coefficient of 1 × 10 ⁵ to 1 × 1
The present invention relates to a transparent conductive laminate obtained by bonding a transparent substrate having a hard coat treatment layer on the outer surface via a transparent pressure-sensitive adhesive layer having a thickness of ⁷ dyn / cm ² and 1 μm or more.

[Structure and operation of the invention]

Various plastic films having transparency can be used as the film substrate used in the present invention,
Specifically, polyethylene terephthalate (PET), polyimide (PI), polyethersulfone (PES), polyetheretherketone (PEEK), polycarbonate (PC), polypropylene (PP), polyamide (PA), polyacryl (PAC) ), Cellulose propionate (CP)
And the like.

The thickness of these film base materials needs to be in the range of 2 to 120 μm, and particularly preferably in the range of 6 to 100 μm. If the thickness is less than 2 μm, the mechanical strength of the base material is insufficient, and it is difficult to continuously form the conductive thin film and the pressure-sensitive adhesive layer by forming the base material into a roll. On the other hand, 120
If it exceeds μm, it will not be possible to improve the scratch resistance and hitting point characteristics of the conductive thin film based on the cushioning effect of the pressure-sensitive adhesive layer described later.

This film substrate is pre-sputtered on its surface,
An etching treatment such as corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation or the like or an undercoating treatment may be performed to improve the adhesion of the conductive thin film provided thereon to the base material. Before providing the conductive thin film, dust removal and cleaning may be performed by solvent cleaning or ultrasonic cleaning as necessary.

In the present invention, a transparent conductive thin film is formed on one surface of such a film substrate. As a method for forming the conductive thin film, any of conventionally known techniques such as a vacuum deposition method, a sputtering method, and an ion plating method can be adopted. Further, the thin film material to be used is not particularly limited, for example, indium oxide containing tin oxide,
In addition to metal oxides such as tin oxide containing antimony, gold, silver, platinum, palladium, copper, aluminum, nickel, chromium, titanium, cobalt, tin or alloys thereof are preferably used.

The thickness of the conductive thin film needs to be 50 Å or more, and if it is thinner than this, it is difficult to form a continuous film having good conductivity with a surface resistance of 10 ³ Ω / □ or less.
On the other hand, if the thickness is too large, the transparency is lowered. Therefore, a particularly preferable thickness is preferably about 100 to 2,000 mm.

On the other surface of the film substrate having such a transparent conductive thin film formed thereon, a transparent substrate having a hard coat treatment layer on its outer surface is attached via a transparent adhesive layer.
In this bonding, the pressure-sensitive adhesive layer is provided on the inner surface of the transparent substrate, that is, the surface of the transparent substrate opposite to the surface on which the hard coat treatment layer is provided, and the film substrate is bonded to the pressure-sensitive adhesive layer. Alternatively, the above-described pressure-sensitive adhesive layer may be provided on the film substrate, and a transparent substrate having a hard coat treatment layer on the outer surface may be bonded thereto. The latter method is more advantageous in terms of productivity because the pressure-sensitive adhesive layer can be formed continuously by making the film base into a roll.

The pressure-sensitive adhesive layer can be used without any particular limitation as long as it has transparency. For example, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, or the like is used. The pressure-sensitive adhesive layer has a function of improving the abrasion resistance and hitting characteristics of the conductive thin film provided on one surface of the film substrate by the cushioning effect after the adhesion of the transparent substrate. From the point of view of better performance,
It is desirable to set the elastic modulus in the range of 1 × 10 ⁵ to 1 × 10 ⁷ dyn / cm ² and the thickness in the range of 1 μm or more, usually ⁵ to 100 μm.

When the above elastic coefficient is less than 1 × 10 ⁵ dyn / cm ² , the pressure-sensitive adhesive layer becomes inelastic, so that it is easily deformed by pressurization to cause irregularities in the film base material and, consequently, the conductive thin film. The adhesive tends to protrude from the cut surface, and the effect of improving the scratch resistance and the hitting point characteristics is reduced. On the other hand, if the elastic modulus exceeds 1 × 10 ⁷ dyn / cm ² , the pressure-sensitive adhesive layer becomes hard and the cushioning effect cannot be expected, so that the abrasion resistance and hitting point characteristics cannot be improved.

When the thickness of the pressure-sensitive adhesive layer is less than 1 μm, the cushioning effect cannot be expected, so that it is impossible to improve the scratch resistance and the hitting point characteristics. If the thickness is too large, transparency is impaired, and it is difficult to obtain good results in terms of formation of the pressure-sensitive adhesive layer, bonding workability expected of transparency, and cost.

The transparent substrate bonded via such an adhesive layer imparts good mechanical strength to the film substrate,
In particular, it contributes to the prevention of the occurrence of curling and the like, and when it is required to be flexible even after bonding, a plastic film of about 6 to 300 μm is usually required. If not, usually 0.05
A glass plate having a thickness of about 10 mm or a plastic film or plate is used. Examples of the material of the plastic include those similar to the above-mentioned film substrate.

In the present invention, the hard coat treatment layer provided on the outer surface of the transparent substrate is a cured coating film made of a curable resin such as melanin resin, urethane resin, alkyd resin, acrylic resin, or silicone resin. It is preferably used.

In forming the cured film, a composition obtained by adding various additives such as an antistatic agent and a polymerization initiator to the above-mentioned curable resin as needed is usually diluted with a solvent to obtain a solid component of about A treatment agent having a concentration of 20 to 80% by weight is prepared and applied to one surface of a transparent gas by a suitable means such as a general solution coating means such as a gravure coater, a reverse coater, a spray coater,
It may be applied by a means such as a slot orifice coater or screen printing so that the film thickness after drying and curing is usually about 1 to 15 μm, and then it is dried by heating and then cured by ultraviolet irradiation, electron beam irradiation or heating.

The hard coat-treated layer thus obtained has a high hardness when the transparent substrate having the treated layer is attached to the film substrate so that the treated layer is on the outer surface side, and the hardness of the treated layer is high and the scratch resistance is high. Due to its excellent properties, it greatly contributes to the improvement of the abrasion resistance of the film substrate, and effectively prevents a decrease in visibility during use as in the prior art.

Prior to the formation of such a hard coat treatment layer, the surface to be adhered, that is, the surface of the transparent substrate, is subjected to corona discharge treatment, ultraviolet irradiation treatment, plasma treatment as pretreatment,
A sputter etching treatment, a primer treatment, and an easy adhesion treatment may be performed, whereby the adhesion between the transparent substrate and the hard coat treatment layer can be increased.

〔The invention's effect〕

As described above, in the present invention, a film base material having a specific thickness is used to form a transparent conductive thin film on one surface of the film base material, while a transparent adhesive layer is formed on the other surface of the film base material. By adopting a structure in which a transparent substrate having a hard coat treatment layer on the surface is bonded, the adhesive layer has excellent scratch resistance and hitting characteristics based on the cushioning effect of the pressure-sensitive adhesive layer. This provides a special effect of providing a transparent conductive laminate in which a decrease in visibility is suppressed.

〔Example〕

Hereinafter, embodiments of the present invention will be described in more detail.

Example 1 One side of a film substrate made of a transparent PET (polyethylene terephthalate) film having a thickness of 12 μm was coated with 4 × 10 ⁻³ Torr of 80% argon gas and 20% oxygen gas.
A transparent conductive thin film (hereinafter, referred to as an ITO thin film) made of a composite oxide of indium oxide and tin oxide having a thickness of 400 mm was formed by a reactive sputtering method using an indium-tin alloy in the atmosphere described above.

Next, on the other surface of the PET film, an acrylic transparent pressure-sensitive adhesive layer (elastic coefficient adjusted to 1 × 10 ⁶ dyn / cm ² ) (weight ratio of butyl acrylate, acrylic acid and vinyl acetate of 100) was used. : 2: 5 100 parts by weight of an acrylic copolymer mixed with 1 part by weight of an isocyanate-based crosslinking agent)
The conductive film was formed to a thickness of μm.

On the other hand, on one side of a transparent substrate made of a transparent PET film having a thickness of 75 μm, 100 parts by weight of an acrylic urethane-based resin (Unitik 17-806 manufactured by Dainippon Ink and Chemicals, Inc.) was added. 5 parts by weight of enylketone (Irgakiure 184 manufactured by Ciba-Geigy Co., Ltd.) was added and a toluene solution prepared by diluting it to a concentration of 50% by weight was applied, dried at 100 ° C for 3 minutes, and immediately thereafter an ozone type high pressure mercury lamp (80W / cm, 15cm collection (Light type) Ultraviolet irradiation was performed with two lamps to form a hard coat treated layer having a thickness of 7 μm, thereby obtaining a hard coat treated film.

Then, the surface of the film opposite to the hard coat treatment layer was bonded to the above-mentioned conductive treatment film via the transparent pressure-sensitive adhesive layer to produce a transparent conductive laminated film of the present invention having the structure shown in the drawing. did.

In the figure, 1 is a transparent film substrate made of PET film having a thickness of 12 μm, 2 is a transparent conductive thin film made of ITO thin film, 3 is an acrylic transparent adhesive layer, and 4 is a thickness. A transparent substrate 5 made of a PET film having a thickness of 75 μm is a hard coat layer.

Examples 2 to 4 As a film substrate, a transparent PES (polyethersulfon) film having a thickness of 25 μm (Example 2) was used.
12.5 μm transparent PI (polyimide) film (Example 3) and 80 μm transparent PC (polycarbonate) film (Example 4) were used in the same manner as in Example 1 except that they were used. Three types of transparent conductive laminated films of the present invention having the structures shown were produced.

Example 5 One side of a film substrate made of a transparent PET film having a thickness of 12 μm was coated with Ag in an atmosphere of (1-2) × 10 ⁻⁴ Torr.
Was formed to a thickness of 120 ° by a vacuum evaporation method to form a transparent conductive thin film, and a transparent conductive laminated film of the present invention having the structure shown in the drawing was produced in the same manner as in Example 1.

Comparative Example 1 A transparent conductive film was produced in the same manner as in Example 1, except that the formation of the pressure-sensitive adhesive layer and the bonding of the transparent substrate having the hard coat treatment layer were not performed.

Comparative Example 2 Thickness without a hard coat treatment layer as a transparent substrate
A transparent conductive laminated film was produced in the same manner as in Example 1, except that a 75 μm PET film was used.

Comparative Example 3 A transparent conductive laminated film was produced in the same manner as in Example 1 except that a PET film having a thickness of 125 μm was used as a film substrate.

Next, for each of the transparent conductive laminated films prepared in Examples 1 to 5 and Comparative Examples 2 and 3 and the transparent conductive film prepared in Comparative Example 1, the surface resistance, light transmittance, abrasion resistance, The hitting point characteristics and visibility were examined in the following manner. The results were as shown in the table below.

<Surface Resistance> Film resistance was measured by a four-terminal method.

<Light Transmittance> The visible light transmittance at a light wavelength of 550 nm was measured using a spectrophotometer UV-240 manufactured by Shimadzu Corporation.

<Scratch resistance> Haydon surface property measuring instrument TYPE-HEIDON14 manufactured by Shinto Kagaku
Scratches: gauze (Japanese Pharmacopoeia Type I)
Load: 100 g / cm ² , Scratch speed: 30 cm / min, Scratch frequency: 10
After rubbing the conductive thin film surface under the condition of 0 times (50 reciprocations), measure the film resistance (Rs), find the rate of change (Rs / Ro) with respect to the initial film resistance (Ro), The sex was evaluated.

<Rotation point characteristics> Two transparent conductive laminated films (or transparent conductive films) are disposed so as to face each other via a spacer having a thickness of 100 μm so that the conductive thin films face each other. From the side of the transparent substrate or film substrate), using a rod made of urethane rubber with a hardness of 40 degrees (key end 7R), perform 100 million centering points with a load of 100 g and then measure the film resistance (Rd). Then, the change rate (Rd / Ro) with respect to the initial film resistance (Ro) was obtained, and the hitting point characteristics were evaluated. The film resistance was measured for the contact resistance at the time of hitting the two transparent conductive laminated films (or transparent conductive films) arranged opposite to each other.

<Visibility> A scratch test was conducted by rubbing the surface of the transparent conductive laminated film (or transparent conductive film) opposite to the surface of the conductive thin film with steel wool # 0000, and the visibility was reduced due to changes in the surface condition. Was visually observed, and the following three grades were evaluated.

A: hardly scratched even when rubbed strongly, and no decrease in visibility was observed. B: scratched when rubbed strongly and reduced in visibility. C: scratched by rubbing lightly with visibility. Is reduced As is evident from the results in the above table, the transparent conductive laminated film of the present invention has excellent scratch resistance and hitting characteristics on the surface of the conductive thin film, and is visually recognized due to the occurrence of surface scratches on the back surface of the film. It can be seen that there is no decrease in the properties.

[Brief description of the drawings]

The drawing is a sectional view showing an example of the transparent conductive laminate of the present invention. 1 ... Transparent film substrate, 2 ... Transparent conductive thin film,
3 ... Transparent adhesive layer, 4 ... Transparent substrate, 5 ... Hard coat treatment layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-104764 (JP, A) JP-A-61-185813 (JP, A) JP-A-63-488 (JP, A) Jpn. 86009 (JP, U)

Claims (1)

(57) [Claims] A transparent conductive thin film having a thickness of 50 ° or more is formed on one surface of a transparent film substrate having a thickness of 2 to 120 μm, and an elastic coefficient of 1 × 10 ⁵ to 1 is formed on the other surface. × 10 ⁷ dyn / cm ² ,
A transparent conductive laminate obtained by laminating a transparent substrate having a hard coat treatment layer on the outer surface via a transparent pressure-sensitive adhesive layer having a thickness of 1 μm or more.