JP2015039837A - Method for manufacturing transparent conductive laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive laminate excellent in flatness, in which an electrode pattern can be formed with high accuracy by post-processing on both surfaces of the laminate, and to provide a method for manufacturing the transparent conductive laminate.SOLUTION: The method for manufacturing a transparent conductive laminate 30 comprises: a step of laminating a first transparent conductive film 10 having at least a hard coat layer 2, 2' and a transparent conductive layer 3, 3' successively deposited on at least one surface of a transparent substrate film 1, 1' with a second transparent conductive film 20 having the similar constitution via an adhesive layer 4 in such a manner that faces of the above films where the transparent conductive layer 3, 3' is not deposited oppose to each other; and a step of heat treating the laminate. A difference in the maximum thermal shrinkage of the laminate is within 0.2% in an oblique direction at an angle of 45 degrees from a flow direction that coincides with flow directions of the first transparent conductive film 10 and of the second transparent conductive film 20 when these films are laminated.

Description

  The present invention relates to a transparent conductive laminate used for flat panel displays such as liquid crystal displays and organic EL displays, and a method for producing the same.

  In display devices such as liquid crystal displays, plasma displays, and organic EL displays, a transparent conductive laminate for a touch panel provided with a hard coat layer and a transparent conductive layer for protecting the surface on a film substrate is used. .

  In these transparent conductive laminates for touch panels, a functional film that provides a function according to the purpose is generally roll-to-roll processed on a transparent plastic film substrate (rolled film raw film). Produced by continuous processing).

  In general, roll-to-roll processing of plastic film base material tends to cause warpage and slip due to winding tension, and sticking and blocking of a smooth coated surface, which adversely affects productivity and quality. It has been known.

  Recently, an optical film laminate has been developed in which two or more types of plastic film base materials are laminated to provide a plurality of higher-level functions.

  In the production of the optical film laminate having higher functions by laminating two or more kinds of plastic film bases as described above, for example, by post-processing such as pattern formation by etching of the transparent conductive layer Further, the warp of the tip becomes a bigger problem, and the flatness of the laminate is required more strictly.

  For these problems, for example, a proposal in Patent Document 1 has been made. Specifically, two film base materials each having a transparent conductive layer are used and laminated such that each of the transparent conductive layers is disposed on the outside, and then electrodes are patterned. Although this proposal is effective for electrode formation, it has no effect on the warp, and a decrease in pattern accuracy due to the warp still remains as an anxiety material.

JP 2009-070191 A

  The present invention provides a transparent conductive laminate that is excellent in flatness and that can accurately form electrode patterns on both sides by post-processing, and a method for producing the same.

  A PET film is manufactured by a biaxial stretching method, and its manufacturing width is as wide as several meters, and it may not be uniformly stretched in the width direction. Therefore, shrinkage occurs when the film is heated above the glass transition temperature, but the magnitude of the shrinkage may not be uniform at the width position. When a film is bonded and a temperature equal to or higher than the glass transition temperature is applied, warping occurs if there is a difference in the size of the heat shrinkage rate in the same direction of the bonded film. The heat shrinkage rate in the film winding direction and the width direction can be adjusted by heat treatment before bonding, but the oblique direction may be different in the two directions and is difficult to adjust.

As means for solving the above-mentioned problems, the invention according to claim 1 is a first transparent conductive film in which at least a hard coat layer and a transparent conductive layer are sequentially laminated on one surface of a transparent substrate film. And a second transparent conductive film having the same configuration, a transparent conductive layer comprising a step of pasting a transparent conductive layer opposite each other and bonding them through an adhesive layer, and a step of heat treatment In the method for manufacturing a laminate,
The difference between the maximum heat shrinkage ratios within 45% oblique to the flow direction oblique 45 degrees in which the directions when the first transparent conductive film and the second transparent conductive film are bonded is within 0.2%. This is a method for producing a transparent conductive laminate.

  The invention described in claim 2 is the method for producing a transparent conductive laminate according to claim 1, wherein the bonding step is performed by a roll-to-roll method.

  According to claim 1 of the present invention, through the adhesive layer, the first transparent conductive film and the second transparent conductive film are inclined at 45 degrees in the flow direction in which the directions when bonded are the same. By bonding the difference in the maximum heat shrinkage ratio with respect to within 0.2%, it is possible to mitigate the occurrence of warpage in the diagonal direction with respect to the flow direction by the heat treatment after bonding.

  Moreover, according to Claim 2, the transparent conductive laminated body excellent in flatness can be continuously manufactured efficiently by performing a bonding process by a roll-to-roll system.

It is a schematic diagram which shows the cross section of the transparent conductive laminated body which concerns on this invention. It is a plane schematic diagram which shows the 45-degree direction which concerns on the thermal contraction of a transparent conductive laminated body.

Hereinafter, the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1 (a), the present invention is similar to the first transparent conductive film 10 formed by sequentially laminating at least a hard coat layer 2 and a transparent conductive layer 3 on one surface of a transparent base film 1. A transparent conductive laminate 30 formed by bonding the second transparent conductive film 20 having the structure of the second transparent conductive film 20 through the adhesive layer 4 so that the other surfaces thereof face each other in the flow direction,
The difference in the maximum thermal shrinkage rate with respect to 45 degrees oblique in the flow direction in which the directions when the first transparent conductive film 10 and the second transparent conductive film 20 are bonded is within 0.2%. A transparent conductive laminate 30 is characterized.

  In the present invention, hard coat layers 2 and 2 ′ may be formed on both surfaces of the transparent base film 1 and 1 ′ as shown in FIG.

  1 (a) and 1 (b), there is a difference in the maximum heat shrinkage rate with respect to 45 degrees oblique in the flow direction between the first transparent conductive film 10 and the second transparent conductive film 20. If it exceeds 0.2%, a warp in an oblique direction, which is considered extremely difficult to correct, occurs.

  FIG. 2 shows the measurement positions D1 and D2 of the thermal contraction rate at 45 degrees oblique to the flow direction according to the present invention, and the corner 1, corner 2, corner 3, and corner 4 for measuring warpage. Note that D1 indicates a diagonal 45 ° direction and D2 indicates a diagonal 45 ° direction. These are measurement positions in the examples described later.

In addition, the thermal contraction rate in the oblique direction of the transparent conductive laminate according to the present invention is the distance L between two points located at D1 and D2 in FIG. 2 of the transparent conductive laminate at room temperature before bonding. _This is expressed as a percentage (%) of (L ₀ -L ₁ ) / L ₀ when the distance L1 between the two points after storage at ₀ , 150 ° C. for 1 hour is used. The heat shrinkage rate in the vertical direction (flow direction) and the horizontal direction (width direction) was also measured by the same measurement in each direction.

  As the transparent base film 1, 1 ′ used in the present invention, a film having transparency, heat resistance, and mechanical strength in a range that does not hinder the processing steps of the present invention, such as a thermoplastic resin and an organic-inorganic composite material. Any substrate can be used.

  Specific examples include polyethylene, polypropylene, polyester, polyvinyl chloride, cellophane, polyamide, polyvinyl alcohol, polycarbonate, polyacetate, akyryl, polystyrene, fluororesin, and triacetyl cellulose.

  Further, the hard coat layers 2 and 2 'are required to have excellent transparency, mechanical properties, heat resistance, chemical resistance, etc. as well as hardness. Specifically, the hard coat layers 2 and 2' are polyfunctional which can be cross-linked. It is desirable to form from an ionizing radiation curable resin obtained by crosslinking monomers and oligomers mainly composed of acrylate.

  As the polyfunctional acrylate, for example, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, polyester acrylate and the like are preferable. These may be used alone or in combination of two or more. In addition to these acrylates, acrylate resins such as epoxy acrylate and urethane acrylate may be used in combination.

  When the ionizing radiation is ultraviolet light, a photopolymerization initiator is required. For example, benzoin, its alkyl ethers, acetophenones, benzophenones, etc. can be used.

  The composition comprising the ionizing radiation curable resin can contain various additives and solvents in order to impart storage stability and coating suitability of the coating liquid.

  Examples of the transparent conductive layers 3 and 3 ′ according to the present invention include materials such as indium / tin composite oxide (ITO), tin oxide, copper, aluminum, nickel, and chromium. It may be composite or laminated. Moreover, as a method of forming a transparent conductive layer using these materials, sputtering method, vacuum deposition method, PVD method of ion plating method, CVD method, coating method, printing method and the like can be used.

  Examples of the pressure-sensitive adhesive layer according to the present invention include, but are not limited to, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive. The thickness is preferably 10 μm to 200 μm. If the thickness is less than 10 μm, sufficient adhesion cannot be ensured, and unevenness in color becomes conspicuous due to slight thickness unevenness. On the other hand, when the thickness exceeds 200 μm, the transparency is inferior and the appearance is inferior. In addition, the total thickness of the transparent conductive laminate is increased, the cost is high, and the productivity is inferior.

  Thus, by heat-treating the second transparent conductive film 20 to which the first transparent conductive film 10 is bonded, the transparent conductive layers 3 and 3 ′ can be crystallized without causing warpage. And the transparent conductive laminated body for touch panels can be manufactured by etching crystallized transparent conductive layers 3 and 3 '.

  Hereinafter, the present invention will be specifically described by way of examples. In the examples, a transparent conductive laminate having a structure in which hard coat layers were formed on both surfaces of a transparent base film as shown in FIG.

(Preparation of transparent conductive film A)
A composition for forming a hard coat layer (DIC: Unidic V-9500) containing an ultraviolet curable acrylic resin on both sides of a polyethylene terephthalate (PET) film having a thickness of 125 μm and a film thickness after UV curing of 3 μm. Then, it was cured by irradiating with ultraviolet rays to form a hard coat layer.

  Next, a transparent conductive layer having a thickness of 30 nm was formed on one surface of the hard coat layer by sputtering ITO to produce a transparent conductive film A.

(Preparation of transparent conductive film B)
A transparent conductive film B was prepared in the same manner as the transparent conductive film A, except that the hard coat layer formation conditions (winding tension, drying temperature, curing conditions) were partially changed.

  The thermal shrinkage rates of the transparent conductive films A and B produced above were measured in the vertical direction, the horizontal direction, and the positions of the direction D1 at 45 degrees to the left and the direction D2 at 45 degrees to the right as shown in FIG. The results are shown in Table 1 below.

<Example 1>
The transparent conductive film A and the transparent conductive film B are pressed and pasted in a roll-to-roll manner through an acrylic adhesive having a film thickness of 25 μm so that the respective flow directions coincide with each other. In addition, a transparent conductive laminate was produced. In addition, both films A and B were bonded together so that the surfaces on which the transparent conductive layer was not laminated faced each other.

<Example 2>
A transparent conductive laminate was produced in the same manner as in Example 1 except that the transparent conductive film B and the transparent conductive film B were bonded together.

<Comparative Example 1>
A transparent conductive laminate was prepared in the same manner as in Example 1 except that the transparent conductive film A and the transparent conductive film A were bonded together.

<Evaluation>
Each of the transparent conductive laminates obtained in Examples 1 and 2 and Comparative Example 1 was cut into 30 cm square, then left at 150 ° C. for 1 hour, then cooled at room temperature for 1 hour and then warped was measured. .

  The warpage was measured by measuring the height of four corners (corner 1, corner 2, corner 3, corner 4 shown in FIG. 2) from the plane when placed on a plane. In addition, in the case of a corner having a curvature that is convex upward, the corner is turned over, the height from the plane is measured, and the value is displayed as minus. The results are shown in Table 2 below.

<Comparison result>
The combination of the transparent base films A and B used in Example 1 is 0.07% in the difference in the maximum heat shrinkage in the oblique 45 degree direction, and the absolute value of the warpage of the four corners is extremely 0-2 mm. It was good. Moreover, the combination of the transparent base material films B used in Example 2 has a difference in the maximum heat shrinkage rate in the oblique 45 degree direction of 0.17%, and the absolute value of the four-angle warpage is 3 to 5 mm. It was good.

  On the other hand, the combination of the transparent base films A used in Comparative Example 1 has a difference in the maximum heat shrinkage in the oblique 45 degree direction of 0.22%, and the absolute value of the four-angle warpage is 5 to 8 mm. In practical use, the values are problematic.

  The present invention can provide a transparent conductive laminate excellent in flatness, for example, easy post-processing according to requirements such as patterning of a transparent conductive layer, and a transparent electrode for various display touch panels and solar cells. Can be used.

DESCRIPTION OF SYMBOLS 1, 1 '... Transparent base film 2, 2' ... Hard-coat layer 3, 3 '... Transparent conductive layer 4 ... Adhesive layer 10 ... First transparent Conductive film 20 ... second transparent conductive film 30 ... transparent conductive laminate D1 ... diagonal left 45 degrees direction D2 ... diagonal right 45 degrees direction

Claims (2)

A transparent conductive layer includes a first transparent conductive film formed by sequentially laminating at least a hard coat layer and a transparent conductive layer on one surface of a transparent base film, and a second transparent conductive film having the same configuration. In the method for producing a transparent conductive laminate comprising the steps of facing each other that are not laminated, and pasting together via an adhesive layer, and a step of heat treatment,
The difference between the maximum heat shrinkage ratios within 45% oblique to the flow direction oblique 45 degrees in which the directions when the first transparent conductive film and the second transparent conductive film are bonded is within 0.2%. A method for producing a transparent conductive laminate.   2. The method for producing a transparent conductive laminate according to claim 1, wherein the bonding step is performed by a roll-to-roll method.

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