JP6364285B2 - Transparent electrode film - Google Patents

Description

  The present invention relates to a transparent electrode film having a transparent electrode layer formed on one side.

  A touch panel generally has a configuration in which a touch panel sensor is disposed on a display device such as a liquid crystal display. The touch panel sensor includes a resistance film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, a capacitance method, and the like. The capacitance method further includes a surface type and a projection type. The projected capacitive method is often used in tablet-type mobile terminals such as smartphones because it can accurately determine the position touched by a finger and can detect multiple points.

  A projected capacitive touch panel sensor has a structure in which a plurality of transparent electrode layers formed in a diamond-like pattern or a fine-line-like pattern are stacked with an insulating transparent substrate interposed therebetween. For example, a touch panel is formed by forming a transparent conductive film on one side of a transparent substrate by sputtering or the like, and bonding a plurality of transparent substrates with a transparent electrode layer formed by patterning the transparent conductive film to form a transparent electrode layer. Yes. As a material for the transparent electrode layer, indium tin oxide (ITO) is often used because of its excellent transparency and conductivity.

  As a transparent base material, a glass plate is conventionally used, and a transparent resin base material is also used in recent years. As the transparent resin substrate, a polyethylene terephthalate (hereinafter also referred to as “PET”) film is often used. The transparent resin base material has a lower surface hardness than the glass plate. Therefore, a hard coat (hereinafter also referred to as “HC”) layer is usually provided on the surface of the transparent resin substrate for the purpose of preventing the surface from being damaged during work. The HC layer may have an antiblocking function to form an antiblocking hard coat (hereinafter also referred to as “ABHC”) layer.

The surface on the transparent electrode layer side of the transparent substrate with a transparent electrode layer has a region where the transparent electrode layer is present and a region where the transparent electrode layer is not present. When the transparent substrate is a transparent resin substrate, the pattern shape of the transparent electrode layer can be seen from the difference in optical properties (light reflectance, transmittance, etc.) between these regions, so-called bone-like appearance Problems are likely to occur.
Therefore, in order to reduce the difference in optical characteristics between these regions and improve bone appearance, an index matching (hereinafter also referred to as “IM”) layer (hereinafter also referred to as “IM”) is used between the transparent resin substrate and the transparent electrode layer. It has been proposed to provide an optical adjustment layer (for example, Patent Document 1).
Further, an IM film in which an IM layer is provided on one side or both sides of a transparent resin substrate is commercially available. In an IM film in which an IM layer is provided on one side of a transparent resin base material, an HC layer is provided on at least the surface of the transparent resin base material opposite to the IM layer side. The HC layer is often an ABHC layer.

In recent years, with the reduction in weight and thickness of portable terminals and the like, the IM film is also required to be thin. If the thickness of the transparent resin substrate is reduced (for example, 75 μm or less) for the purpose of thinning the IM film, the rigidity is lowered and the transparent electrode layer is easily deformed when formed. For example, it tends to shrink due to heat during sputtering or subsequent sintering. When the transparent resin substrate is deformed, the accuracy of the shape of the formed transparent electrode layer is lowered.
Therefore, a low thermal shrinkage treatment is performed on the transparent resin base material, and further, a rigid protective film is bonded to the IM film, and a transparent electrode layer is formed on the IM layer in that state.
After forming the transparent electrode layer, the protective film is peeled off, and a transparent optical adhesive (Optical Clear Adhesive; hereinafter also referred to as “OCA”) layer with a separator is laminated on the peeled surface to form the transparent electrode layer and the IM film. And an OCA layer and a separator are laminated. Then, the separator of this laminated body is peeled, the exposed OCA layer surface is bonded to a display device or another transparent substrate with a transparent electrode layer, and a touch panel is assembled.

JP-A-8-240800

  As described above, a laminate in which a transparent electrode layer, an IM film, an OCA layer, and a separator are laminated has many processes and members necessary for production, and costs are high.

  An object of this invention is to provide the film for transparent electrodes useful for the simplification of the manufacturing process of a touch panel, and cost reduction.

The film for transparent electrodes of the present invention is a film in which a transparent electrode layer is formed on one side,
From the side on which the transparent electrode layer is formed, an IM layer, a transparent resin base material, an OCA layer, and a separator are laminated in this order,
The transparent resin substrate and the OCA layer are in contact with each other through an adjacent or easy adhesion layer.

  ADVANTAGE OF THE INVENTION According to this invention, the film for transparent electrodes useful for the simplification of the manufacturing process of a touch panel and cost reduction can be provided.

It is sectional drawing which shows typically one Embodiment of the film for transparent electrodes of this invention.

FIG. 1 is a cross-sectional view schematically showing one embodiment of the transparent electrode film of the present invention.
The transparent electrode film 1 of the present embodiment has a transparent electrode layer formed on one side. That is, the transparent electrode film 1 is used for producing a laminate in which the transparent electrode film 1 and the transparent electrode layer are laminated.

In the transparent electrode film 1, the IM layer 3, the transparent resin base material 5, the OCA layer 7, and the separator 9 are laminated in this order from the side on which the transparent electrode layer is formed.
The transparent resin substrate 5 and the OCA layer 7 are adjacent to each other.
The IM layer 3 is disposed on the outermost layer on the side where the transparent electrode layer is formed. That is, the IM layer 3 constitutes a surface on which the transparent electrode layer is formed (hereinafter also referred to as “transparent electrode layer forming surface”) 1a.

(IM layer)
When a transparent electrode layer is formed on the transparent electrode layer forming surface 1a of the transparent electrode film 1 in a diamond-like or fine-line-like pattern, the transparent electrode layer side surface of the resulting laminate is There are a region where the transparent electrode layer is not present and a region where it is present. If the transparent resin substrate 5 is exposed in a region where the transparent electrode layer does not exist, a difference in optical characteristics (light reflectance, transmittance, etc.) is large, and thus a problem of bone appearance is likely to occur.
The IM layer 3 is a layer having a function of reducing the difference between the optical characteristics of the region where the transparent electrode layer is present and the optical characteristics of the region where the transparent electrode layer is not present. Bone appearance is suppressed by the presence of the IM layer 3.

The configuration of the IM layer 3 is not particularly limited, and a known IM layer configuration can be adopted. Examples thereof include those composed of a low refractive index layer, those composed of a high refractive index layer, and those composed of a combination of a low refractive index layer and a high refractive index layer. In the above combination, a plurality of high refractive index layers and low refractive index layers may exist.
As a configuration in which the low refractive index layer and the high refractive index layer are combined, a configuration in which the high refractive index layer and the low refractive index layer are laminated in this order from the transparent resin substrate 5 side is preferable.

A low refractive index layer is a layer whose refractive index is lower than the refractive index of the transparent electrode layer formed on the transparent electrode layer forming surface 1a. For example, when the transparent electrode layer is ITO, the refractive index of the low refractive index layer is preferably 1.40 to 1.55, and more preferably 1.45 to 1.50.
In the present invention, the “refractive index” is a value measured by an Abbe refractometer of the coating film after curing.
Examples of the material for the low refractive index layer include acrylate resins, silicon dioxide fine particles, and hollow silica containing or coordinated with a low refractive index material such as a fluorine compound or silicone.

Examples of the method for forming the low refractive index layer include a wet method and a dry method, and any method may be used.
Examples of the wet method include roll coating, spin coating, and spray coating.
Examples of the dry method include sputtering, ion plating, and plasma CVD. The roll coating method is particularly preferable because it is advantageous for cost reduction.

The high refractive index layer is a layer having a refractive index higher than that of the low refractive index layer. For example, when the refractive index of the low refractive index layer is 1.50, the refractive index of the high refractive index layer is preferably 1.62 to 1.66, and more preferably 1.64 to 1.65.
Examples of the material for the high refractive index layer include metal oxide films such as zirconia and titania, and resins in which metal oxide fine particles are dispersed.

  As a method for forming the high refractive index layer, there are a wet method, a dry method and the like, as in the case of the low refractive index layer, and either method may be used. A method of coating a resin in which zirconia particles are dispersed by a roll coating method is particularly preferable because it is advantageous for cost reduction.

The IM layer 3 may have a hard coat property.
“Has a hard coat property” means that the pencil hardness test (JIS K5600-5-4) indicates a hardness of H or higher.
The IM layer having hard coat properties can be formed, for example, by curing an acrylate resin in which zirconia fine particles are dispersed.

(Transparent resin base material)
There is no restriction | limiting in particular as transparent resin which comprises the transparent resin base material 5, For example, PET, a triacetyl cellulose (TAC), a polyethylene naphthalate (PEN), a polymethylmethacrylate (PMMA), a polycarbonate (PC), a polyimide (PI) ), Polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), cycloolefin copolymer (COC), norbornene resin, acrylic resin, polyethersulfone, cellophane, aromatic polyamide, etc. Can be mentioned. Among these, PET is preferable.

The total light transmittance (JIS K7105: 2010) of the transparent resin substrate 5 is preferably 90% or more, and more preferably 91% or more.
The refractive index of the transparent resin substrate 5 is preferably 1.59 to 1.65, more preferably 1.63 to 1.64.

The thickness of the transparent resin substrate 5 is preferably thin from the viewpoint of weight reduction. In addition, when the thickness of the transparent resin substrate 5 is large, it has sufficient rigidity, so that even when the OCA layer 7 and the separator 9 are not present, the transparent resin substrate 5 is not easily deformed when the transparent electrode layer is formed. Therefore, in terms of usefulness of the present invention, the thickness of the transparent resin substrate 5 is preferably 75 μm or less, more preferably 50 μm or less, and further preferably 25 μm or less.
Although the minimum of the thickness of the transparent resin base material 5 is not specifically limited, When productivity, a handleability, etc. are considered, 5 micrometers or more are preferable and 10 micrometers or more are more preferable.

  The surface of the transparent resin substrate 5 may be subjected to treatment such as easy adhesion treatment, corona treatment, and plasma treatment.

(OCA layer)
The OCA layer 7 is a transparent adhesive layer.
The total light transmittance (JIS K7105) of the OCA layer 7 is preferably 85% or more, and more preferably 90% or more.

The OCA layer 7 is required to be acid free, heat resistant, etc. in addition to transparency.
For example, after a transparent electrode layer is formed on each of the plurality of transparent electrode films 1, the OCA layer 7 and the transparent electrode layer are in contact with each other when they are bonded together. When the OCA layer 7 contains an acid component, the acid component moves to the transparent electrode layer, and there is a risk that the ITO or the like corrodes and the performance deteriorates. Therefore, the OCA layer 7 is required to contain no acid component. .
Moreover, in a smart phone etc., the inside of a device becomes a high-temperature, high-humidity environment during operation. Therefore, heat resistance that does not cause appearance abnormality such as discoloration and foaming when exposed to a temperature of about 80 ° C. is required.
Furthermore, in the present invention, since the transparent electrode layer is formed on the transparent electrode layer forming surface 1a of the transparent electrode film 1 in a state where the OCA layer 7 is laminated, the transparent electrode layer is formed on the OCA layer 7. Heat resistance to the heat at the time is also necessary. For example, when ITO is formed by sputtering, heat of about 100 to 150 ° C. is applied at the time of sputtering, and sintering is performed to increase the refractive index after film formation, so that the temperature is about 150 ° C. for about 1 hour. There is a need for heat resistance that does not cause abnormal appearance such as discoloration and foaming when exposed.

The OCA layer 7 is formed from a pressure-sensitive adhesive composition designed to satisfy the above characteristics.
The pressure-sensitive adhesive composition generally contains a base resin and optionally contains optional components. The characteristics of the OCA layer 7 can be adjusted by the type of the base resin and the type and content of the optional component.
Examples of the base resin include acrylic resins, urethane resins, and silicone resins.
As an arbitrary component, a well-known additive can be used, for example, an epoxy-type additive, an isocyanate additive, etc. are mentioned.
Although the commercially available OCA layer does not consider the heat resistance against heat when the transparent electrode layer is formed, any commercially available OCA layer may be used for the OCA layer 7 as long as it satisfies the above characteristics. .

  The thickness of the OCA layer 7 is preferably 10 to 200 μm, and more preferably 25 to 100 μm. If the thickness of the OCA layer 7 is not less than the lower limit of the above range, the adhesive strength and durability are more excellent, and if it is not more than the upper limit, transparency, smoothness and the like are more excellent.

(separator)
It does not specifically limit as the separator 9, A well-known thing can be used as a separator laminated | stacked on an OCA layer. For example, what provided the mold release layer on the single side | surface (OCA layer 7 side) or both surfaces of the resin film is mentioned.
Examples of the resin constituting the resin film include PET, acrylic, polypropylene, and polyethylene. Among these, PET is preferable.
Examples of the release layer include those obtained by applying and curing a coating agent containing a silicone resin and a liquid medium.

  10-200 micrometers is preferable and, as for the thickness of the separator 9, 25-125 micrometers is more preferable. If the thickness of the separator 9 is not less than the lower limit of the above range, the deformation of the transparent electrode film 1 at the time of forming the transparent electrode layer is sufficiently suppressed, and if it is not more than the upper limit, the cost and the like are suppressed.

(Method for producing transparent electrode film)
As a manufacturing method of the film 1 for transparent electrodes, the following manufacturing method is mentioned, for example.
(1) A pressure-sensitive adhesive composition is applied to the surface of a transparent resin film (transparent resin base material), dried to form the OCA layer 7, and then a separator 9 is bonded to the OCA layer 7. And a step of obtaining a first laminate in which the OCA layer 7 and the separator 9 are laminated in this order;
(2) The process of forming the IM layer 3 in the surface at the side of the transparent resin film of said 1st laminated body, and obtaining the film 1 for transparent electrodes.
In the step (1), a pressure-sensitive adhesive composition may be applied to the separator 9 and a transparent resin film may be bonded to the formed OCA layer 7.

  In the step (1), a method for applying the pressure-sensitive adhesive composition is not particularly limited, and a known method such as a wet coating method or a printing method can be used. Examples of wet coating methods include air doctor coating, bar coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray coating, slot orifice coating, calendar coating, and dam coating. , Dip coating, die coating and the like. Examples of the printing method include intaglio printing methods such as gravure printing and printing such as stencil printing methods such as screen printing.

In the step (2), the IM layer 3 can be formed by a known method as described above.
When forming the IM layer 3, the transparent resin film may be reduced in heat shrinkage. The low heat shrinkage can be performed by, for example, heat stretching.

(Use)
As described above, the transparent electrode film 1 is used for producing a laminate in which the transparent electrode film 1 and the transparent electrode layer are laminated.
Such a laminate is useful for a projected capacitive touch panel sensor.

The material of the transparent electrode layer is not particularly limited and may be a known material. Examples thereof include ITO, indium oxide, tin oxide, zinc oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, indium-zinc composite oxide, silver and silver alloy, copper and copper alloy, and gold.
The transparent electrode layer may be a single layer or a multilayer structure.

The laminate can be produced, for example, by forming a transparent conductive film on the transparent electrode layer forming surface 1a of the transparent electrode film 1, and patterning the transparent conductive film to form a transparent electrode layer.
As a method for forming the transparent conductive film, a known method can be appropriately used. For example, a vacuum deposition method, a sputtering method, a chemical vapor deposition (CVD) method, an ion plating method, a spray method, and the like can be given.
In the case of the sputtering method, a normal sputtering method using an oxide target, a reactive sputtering method using a metal target, or the like is used. At this time, oxygen, nitrogen, or the like may be introduced as a reactive gas, or means such as ozone addition, plasma irradiation, or ion assist may be used in combination. In addition, a bias such as direct current, alternating current, and high frequency may be applied to the substrate as long as the object of the present invention is not impaired.
After film formation, in order to increase the refractive index of the transparent conductive film, it is preferable to perform a sintering process at 135 to 170 ° C. for about 1 to 2 hours.
As a method for patterning the transparent conductive film, a known method can be appropriately used. For example, a method of forming a resist pattern on a transparent conductive film by a known photolithography method and etching the transparent conductive film using the resist pattern as a mask can be mentioned.

(Function and effect)
Since the transparent electrode film 1 has the above-described configuration, it is useful for simplifying the touch panel manufacturing process and reducing the cost.
That is, conventionally, when manufacturing an IM film, a process of forming an HC layer (ABHC layer) on one side or both sides of a transparent resin base material and further forming an IM layer is performed. Further, when manufacturing a laminate in which a transparent electrode layer, an IM film, an OCA layer, and a separator are laminated from an IM film, a step of attaching a protective film to the IM film, and forming a transparent conductive film on the IM film The process, the process of patterning a transparent conductive film, the process of peeling a protective film, and bonding an OCA layer with a separator, etc. are performed.
In the present invention, the OCA layer 7 and the separator 9 are laminated on the transparent resin base material 5, whereby the transparent resin base material 5 can be prevented from being damaged during work. Therefore, it is not necessary to provide an HC layer (ABHC layer) as in the prior art.
Further, since the OCA layer 7 and the separator 9 are laminated, the transparent electrode film 1 as a whole has sufficient rigidity even if the thickness of the transparent resin substrate 5 is thin. It is possible to prevent deformation of the transparent resin substrate 5 when the transparent electrode layer is formed on the transparent electrode layer forming surface 1a. Therefore, there is no need to laminate a protective film as in the prior art. Moreover, the OCA layer 7 is not peeled after forming the transparent electrode layer on the transparent electrode layer forming surface 1a of the transparent electrode film 1, and can be used as it is for a touch panel.
Therefore, the number of processes and the members to be used can be reduced as compared with the prior art.

  The transparent electrode film of the present invention has been described with reference to the embodiment, but the present invention is not limited to the above embodiment. Each configuration in the above embodiment, a combination thereof, and the like are examples, and the addition, omission, replacement, and other modifications of the configuration can be made without departing from the spirit of the present invention.

The film for transparent electrodes of the present invention may further have a layer other than the IM layer, the transparent resin substrate, the OCA layer, and the separator.
For example, in the embodiment, the IM layer 3 and the transparent resin base material 5 are adjacent to each other, but another layer may be provided between the IM layer 3 and the transparent resin base material 5. Other layers include an easy adhesion layer, an HC layer (may be an ABHC layer), a polarizing layer, a light diffusing layer, a low reflection layer, an antifouling layer, an antistatic layer, and an ultraviolet / near infrared (NIR) absorption. Layer, electromagnetic wave shielding layer, and the like.
In the said embodiment, although the transparent resin base material 5 and the OCA layer 7 are adjacent, you may have an easily bonding layer between the transparent resin base material 5 and the OCA layer 7. FIG. However, no layer other than the easy adhesion layer is included between the transparent resin substrate 5 and the OCA layer 7.

Although it does not specifically limit as a component which comprises an easily bonding layer, For example, a polyester resin, an epoxy resin, an alkyd resin, an acrylic resin, a urea resin, a urethane resin etc. are mentioned. Among these, at least one selected from polyester resins, acrylic resins, and urethane resins is preferable from the viewpoint of adhesiveness. A combination of polyester resin and acrylic resin, polyester resin and urethane resin, or acrylic resin and urethane resin may be used.
When the transparent resin substrate is a PET film, a polyester resin is particularly preferable as a component constituting the easy adhesion layer. The refractive index of the polyester resin is a value close to the refractive index of the PET film (about 1.65). By using the polyester resin, the refractive index difference between the easy-adhesion layer and the PET film can be reduced, and interference is caused. Unevenness can be suppressed.
The thickness of the easy adhesion layer is preferably 20 nm or more and 200 nm or less, more preferably 50 nm or more and 150 nm or less, in order to bring out the effect of suppressing interference unevenness.

DESCRIPTION OF SYMBOLS 1 Transparent electrode film 1a Transparent electrode layer formation surface 3 IM layer (index matching layer)
5 Transparent resin base material 7 OCA layer (transparent adhesive layer for optics)
9 Separator

Claims (2)

In the film where the transparent electrode layer is formed on one side,
From the side on which the transparent electrode layer is formed, an index matching layer, a transparent resin base material, an optical transparent adhesive layer, and a separator are laminated in this order,
A transparent electrode film, wherein the transparent resin substrate and the optical transparent adhesive layer are in contact with each other through an adjacent or easy adhesion layer.   The transparent electrode film according to claim 1, wherein the transparent resin substrate has a thickness of 75 μm or less.

Images