JP6801952B2 - Conductive film - Google Patents

Description

The present invention relates to a conductive film.

Conventionally, a conductive layer is formed on a functional element such as an electromagnetic wave shield sheet, a flat panel display, a sensor, a solar cell, etc. by fusing, plating, vapor deposition, etc. of a metal foil on the surface of a resin film such as a polyethylene terephthalate (PET) film. A conductive film is used. Cu is often used for the conductive layer because of its low electrical resistivity and low cost (Patent Document 1 and the like).

In general, since the adhesiveness of a conductive layer containing a metal to a resin film is low, a technique for forming a coating film having adhesiveness to the conductive layer between the resin film and the conductive layer has been proposed (for example, Patent Document 2).

JP-A-2015-0563221 Japanese Patent No. 5697223

By the way, a conductive film using a conventional PET film cannot be used under a polarizing plate because it has a phase difference of several thousand nm depending on the thickness, or it may be colored when a large display is viewed from an angle. The rainbow pattern may become noticeable and visibility may decrease. Therefore, in order to control the phase difference, a cycloolefin resin film may be used as a base material.

Since the cycloolefin-based resin film is soft, the resin film may be scratched or cracked in the manufacturing process of the conductive film or the like. Although this can be dealt with by forming a cured resin layer on the cycloolefin resin film, the adhesion of the cured resin layer to the conductive layer is often insufficient. It can be dealt with by further providing a layer that enhances the adhesion between the cured resin layer and the conductive layer, but in this case, at least two layers must be provided between the resin film and the conductive layer, which is a process. There is room for improvement in terms of simplification and cost reduction.

Further, as a part of increasing the functionality of functional elements, it is required to reduce the resistance of the conductive film. Although such a requirement can be met by increasing the thickness of the conductive layer, the resin film of the conductive layer can be provided with a coating film having the above-mentioned adhesiveness in the thick conductive layer. It has been found that peeling from the resin may occur.

An object of the present invention is to provide a conductive film capable of simplifying a manufacturing process and having sufficient adhesion even in a thick conductive layer.

As a result of diligent studies to solve the above problems, the present inventors have found that the above object can be achieved by adopting the following configuration, and have arrived at the present invention.

The conductive film of the present invention is provided with an easy-adhesion layer which is a cured film of an adhesive resin composition and a conductive layer containing copper in this order on one surface side of a cycloolefin resin film.
A hard coat layer is provided on the other surface side of the cycloolefin resin film.
60% or more of the grids of the conductive layer having a thickness of 1 μm did not peel off after the grid peeling test.

In the conductive film, the number of squares that did not peel off after the grid peeling test on the conductive layer having a thickness of 1 μm can be 60% or more. As a result, sufficient adhesion can be exhibited even if the thickness is several times thicker (on the order of μm) than the thickness of the conventional conductive layer. Further, since it is only necessary to provide one layer of the easy-adhesion layer between the cycloolefin-based resin film and the conductive layer, the manufacturing process of the conductive film can be simplified and the cost can be reduced. Further, an easy-adhesion layer, which is a cured film of the adhesive resin composition, is provided on one surface side of the cycloolefin resin film, and a hard coat layer is provided on the other surface side, so that the film is relatively brittle. It is possible to prevent the cycloolefin resin film from being scratched or cracked.

The adhesive resin composition preferably contains at least one of a (meth) acrylate monomer and a (meth) acrylate oligomer. As a result, it becomes easy to form a crosslinked structure due to the C = C double bond contained in the acryloyl group, and the film strength can be efficiently improved. As a result, the film breakage of the easy adhesion layer and the conductive layer Interfacial peeling between the and the easy adhesion layer is suppressed, and good adhesion can be exhibited.

It is preferable that the adhesive resin composition has ultraviolet curability. As a result, the formation of a crosslinked structure can be promoted only by irradiating with ultraviolet rays while avoiding thermal damage to the cycloolefin resin film and the conductive layer in the case of heat curing, so that it is stable and efficient. A conductive film can be formed.

The thickness of the easy-adhesion layer is preferably 0.2 μm to 2 μm. By setting the thickness of the easy-adhesion layer within the above range, the adhesion can be exhibited at a higher level, and the flexibility of the easy-adhesion layer can be maintained to prevent the conductive film from being broken due to the destruction of the easy-adhesion layer. Breakage can be prevented.

The thickness of the conductive layer may be 2 nm to 1000 nm. Even when the thickness of the conductive layer is within the above range, the conductive film is provided with a specific easy-adhesion layer, so that the adhesion of the conductive layer can be ensured.

The hard coat layer may contain particles. As a result, the conductive film can be imparted with an anti-blocking action, and for example, production by a roll-to-roll method can be efficiently performed.

It is a schematic cross-sectional view of the conductive film which concerns on one Embodiment of this invention.

Embodiments of the conductive film of the present invention will be described below with reference to the drawings. However, in some or all of the figures, parts unnecessary for explanation are omitted, and some parts are enlarged or reduced for ease of explanation. The terms indicating the positional relationship such as up and down are used merely for the sake of facilitation of explanation, and there is no intention of limiting the configuration of the present invention.

《Conductive film》
FIG. 1 is a schematic cross-sectional view of a conductive film according to an embodiment of the present invention. The conductive film 10 shown in FIG. 1 includes an easy-adhesion layer 2 and a conductive layer 3 on one surface side of the cycloolefin resin film 1 in this order. Although the easy-adhesion layer 2 and the conductive layer 3 each have a structure of one layer, each may have a multi-layer structure of two or more layers. Further, a hard coat layer 4 is provided on the other surface side of the cycloolefin resin film 1.

In the conductive film 10, the number of squares that did not peel off after the grid peeling test for the conductive layer having a thickness of 1 μm was 60% or more, preferably 80% or more, and more preferably 95% or more. As a result, sufficient adhesion can be exhibited even if the thickness of the conductive layer is increased to several times the thickness (on the order of μm) of the thickness of the conventional conductive layer.

(Cycloolefin resin film)
The cycloolefin-based resin film (hereinafter, also simply referred to as “resin film”) 1 is formed of a cycloolefin-based resin and has properties such as high transparency, low retardation, and low water absorption. By adopting the cycloolefin resin film 1, the optical characteristics of the conductive film 10 can be controlled.

The cycloolefin-based resin that forms the cycloolefin-based resin film 1 is not particularly limited as long as it is a resin having a monomer unit composed of a cyclic olefin (cycloolefin). The cycloolefin-based resin used in the cycloolefin-based resin film 1 may be either a cycloolefin polymer (COP) or a cycloolefin copolymer (COC). The cycloolefin copolymer refers to a non-crystalline cyclic olefin resin which is a copolymer of a cyclic olefin and an olefin such as ethylene.

As the cyclic olefin, there are a polycyclic cyclic olefin and a monocyclic cyclic olefin. Examples of such polycyclic cyclic olefins include norbornene, methylnorbornene, dimethylnorbornene, ethylnorbornene, etilidennorbornene, butylnorbornene, dicyclopentadiene, dihydrodicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene, and tetracyclododecene. , Methyltetracyclododecene, dimethylcyclotetradodecene, tricyclopentadiene, tetracyclopentadiene and the like. Examples of the monocyclic cyclic olefin include cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctadiene, cyclododecatriene and the like.

The optical film made of the above cycloolefin resin is also available as a commercial product. For example, Topas manufactured by Ticona, Arton manufactured by JSR, ZEONOR, ZEONEX manufactured by Zeon Corporation, and Appel manufactured by Mitsui Chemicals Co., Ltd. Can be mentioned.

The thickness of the cycloolefin-based resin film 1 is preferably in the range of 2 to 200 μm, and more preferably in the range of 10 to 100 μm. If the thickness of the cycloolefin-based resin film 1 is less than the lower limit of the above range, the mechanical strength of the cycloolefin-based resin film 1 is insufficient, and the film base material is made into a roll to continuously form the easy-adhesion layer 2 and the conductive layer 3. It may be difficult to form the film.

The surface of the cycloolefin resin film 1 is preliminarily subjected to etching treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, and oxidation, and undercoating treatment, so that the cycloolefin resin film 1 is easily adhered to the resin film 1. Or the adhesion to the conductive layer or the like may be improved. Further, the surface of the resin film may be dust-removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like, if necessary, before forming the easy-adhesion layer or the conductive layer.

(Easy adhesive layer)
The easy-adhesive layer 2 is a cured film of an adhesive resin composition. In the conductive film 10, 60% or more of the squares that did not peel off after the grid peeling test on the conductive layer having a thickness of 1 μm are 60% or more, so that the easy-adhesion layer 2 is attached to the conductive layer 3 containing copper. Has good adhesion.

As the adhesive resin composition, one having sufficient adhesiveness and strength as a cured film after forming the easy-adhesion layer can be used without particular limitation. Examples of the resin used include thermosetting resins, thermoplastic resins, ultraviolet curable resins, electron beam curable resins, two-component mixed resins, and mixtures thereof. Among these, curing treatment by ultraviolet irradiation Therefore, an ultraviolet curable resin that can efficiently form an easy-adhesion layer by a simple processing operation is preferable. By including the ultraviolet curable resin, an adhesive resin composition having ultraviolet curability can be easily obtained.

As the adhesive resin composition, a material that forms a crosslinked structure at the time of curing is preferable. When the crosslinked structure in the easy-adhesion layer is promoted, the internal structure of the film, which had been loose until then, becomes stronger and the film strength is improved. This is because it is presumed that such improvement in film strength contributes to improvement in adhesion. That is, as the thickness of the conductive layer increases, the internal stress in the conductive layer increases, and the stress generated between the conductive layer and the easy-adhesion layer also increases. The conventional easy-adhesion layer cannot withstand the increase in stress in the conductive layer, and causes film fracture or peeling at the interface between the conductive layer and the easy-adhesion layer (hereinafter, also referred to as “interfacial peeling”). On the other hand, since the conductive film includes an easy-adhesion layer in which the crosslinked structure is promoted and the film strength is increased, film breakage and interfacial peeling of the easy-adhesion layer are suppressed, and good adhesion can be exhibited.

The adhesive resin composition preferably contains at least one of a (meth) acrylate monomer and a (meth) acrylate oligomer. As a result, it becomes easy to form a crosslinked structure due to the C = C double bond contained in the acryloyl group, and the film strength can be efficiently improved. In addition, in this specification, (meth) acrylate means acrylate or methacrylate.

The formation of the crosslinked structure can be confirmed by the following method. The ratio to the absorbance _{Ab 1450} at 1450 cm ^-1 due to C-H absorbance _{Ab 1410 (Ab 1410 / Ab 1450} ) is a predetermined value or less at 1410 cm ^-1 attributable to the C = C-H in FT-IR measurement It should be. The specific ratio (Ab ₁₄₁₀ / Ab ₁₄₅₀ ) is preferably 1.10 or less. Since the absorbance has a certain proportional relationship with the abundance of the target bond, the smaller the absorbance Ab _{1410 at 1410} cm ^-1 , the smaller the abundance of C = CH bonds attributed to the peak. Corresponds to becoming. In the process of forming the easy-adhesion layer, the C = C double bond in the C = C—H bond is radically added to the other C = C double bond in the system to form a kind of crosslinked structure. As a result, the crosslinked structure in the easy-adhesion layer is promoted. This is because the fact that the C = C double bond is cleaved and consumed in the formation of the crosslinked structure means that the abundance of the C = CH bond is reduced.

The (meth) acrylate monomer and / or the acrylate oligomer having a (meth) acryloyl group as a main component used in the present embodiment has a role of forming a coating film, and specifically, trimethylolpropane tri (meth) acrylate. , Ethylene oxide-modified trimethylolpropantri (meth) acrylate, propylene oxide-modified trimethylolpropanthry (meth) acrylate, trimethylolpropanetetra (meth) acrylate, tris (acryloxyethyl) isocyanurate, caprolactone-modified tris (acryloxyethyl) ) Isocyanurate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, alkyl-modified dipentaerythritol tri (meth) acrylate, alkyl Examples thereof include modified dipentaerythritol tetra (meth) acrylate, alkyl-modified dipentaerythritol penta (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, and a mixture of two or more thereof.

Among the above (meth) acrylates, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, or a mixture thereof is considered to have abrasion resistance and curability. Especially preferable.

Moreover, urethane acrylate oligomer can also be used. The urethane (meth) acrylate oligomer can be prepared by reacting a polyol with a polyisocyanate and then reacting the (meth) acrylate having a hydroxyl group, or by reacting the polyisocyanate with a (meth) acrylate having a hydroxyl group. , A method of reacting a polyol, a method of reacting a polyisocyanate, a polyol, or a (meth) acrylate having a hydroxyl group, and the like are not particularly limited.

Examples of the polyol include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol and copolymers thereof, ethylene glycol, propylene glycol, 1,4-butanediol, 2,2'-thiodiethanol and the like.

Examples of the polyisocyanate include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylenedi isocyanate, p-phenylenedi isocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-. Examples thereof include diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,3-xylylene diisocyanate, and 1,4-xylylene diisocyanate.

If the crosslink density is too high, the performance as a primer deteriorates and the metal adhesion tends to decrease. Therefore, a low-functional (meth) acrylate having a hydroxyl group (hereinafter referred to as a hydroxyl group-containing (meth) acrylate) may be used. Examples of the hydroxyl group-containing (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. , 4-Hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3-acryloyloxyprocyl (meth) acrylate, pentaerythritol tri (meth) acrylate and the like. .. The (meth) acrylate monomer component and / or the (meth) acrylate oligomer component described above may be used alone or in combination of two or more.

The ultraviolet curable adhesive resin composition of the present embodiment preferably contains a thiourea type silane coupling agent as the silane coupling agent. As a result, the adhesive force of the conductive layer as a primer is improved. The thiourea type silane coupling agent is an alkoxysilane coupling agent having a structure represented by the following general formula (1), and is commercially available as X-12-1016M, X-12-1111, X-12-1116, X. -12-1117 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name) can be mentioned.

Further, the anti-blocking property is improved by blending a (meth) acrylic group-containing silane coupling agent. Examples of the (meth) acrylic group-containing silane coupling agent include 3-acryloyloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and the like. Examples thereof include 3-methacryloxypropyltriethoxysilane, and examples of commercially available products include KR-513 and KBM-5103 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name).

When the thiourea type silane coupling agent and the (meth) acrylic group-containing silane coupling agent are used in combination, 50 to 150 parts by weight of the (meth) acrylic group-containing silane coupling agent is compared with 100 parts by weight of the thiourea type silane coupling agent. Is preferable.

The blending amount of the silane coupling agent is 0.1 parts by weight to 50 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the (meth) acrylate monomer and / or (meth) acrylate oligomer. .. Within this range, the adhesion to the conductive layer is improved, and the physical properties of the coating film can be maintained.

The easy-adhesion layer 2 of the present embodiment may contain nanosilica fine particles. As the nanosilica fine particles, organosilica sol synthesized from alkylsilane or nanosilica synthesized by plasma arc can be used. Examples of commercially available products include PL-7-PGME (manufactured by Fuso Chemical Co., Ltd., trade name) for the former, and SIRMIBK15WT% -M36 (manufactured by CIK Nanotech, trade name) for the latter. The blending ratio of the nanosilica fine particles is preferably 5 to 30 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of the total weight of the (meth) acrylate monomer having a (meth) acryloyl group and / or the acrylate oligomer and the silane coupling agent. Parts by weight are more preferred. By setting it to the lower limit or higher, surface irregularities are formed and anti-blocking property can be imparted, and roll-to-roll production becomes possible. By setting the value to the upper limit or less, it is possible to prevent a decrease in adhesion to the conductive layer.

The average particle size of the nanosilica fine particles is preferably 100 to 500 nm. If the average particle size is less than 100 nm, the amount of addition required to form irregularities on the surface is large, so that adhesion with the conductive layer cannot be obtained. On the other hand, if it exceeds 500 nm, the haze becomes large and the visibility deteriorates. Problems occur.

The adhesive resin composition preferably contains a photopolymerization initiator in order to impart ultraviolet curability. Examples of the photopolymerization initiator include benzoin ethers such as benzoin normal butyl ether and benzoin isobutyl ether, benzyl ketals such as benzyl dimethyl ketal and benzyl diethyl ketal, and acetophenone such as 2,2-dimethoxyacetophenone and 2,2-diethoxyacetophenone. , 1-Hydroxycyclohexylphenyl ketone, [2-hydroxy-2-methyl-1- (4-ethylenephenyl) propan-1-one], 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-Hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-2-methyl-1- (4-isopropylphenyl) propane-1- Α-Hydroxyalkylphenones such as on, 2-methyl-1- [4- (methylthio) phenyl] -1-morpholinopropane, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl)- Α-Aminoalkylphenones such as 1-butanone, monoacylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,6- Examples thereof include monoacylphosphine oxides such as dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide.

Alkylphenone-based photopolymerization initiators are preferable from the viewpoints of resin curability, photostability, compatibility with resin, low volatility, and low odor, and 1-hydroxycyclohexylphenylketone and 2-hydroxy-2-methyl-1 are preferable. -Phenyl-propan-1-one, (2-hydroxy-1-{4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane-1-one, 1 -[4- (2-Hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1-one is more preferable. Commercially available products include Irgacure 127, 184, 369, 651, 500, 891 and 907. , 2959, Benzyl1173, TPO (manufactured by BASF Japan Co., Ltd., trade name), etc. The photopolymerization initiator is based on 100 parts by weight of a (meth) acrylate monomer having a (meth) acryloyl group and / or an acrylate oligomer. Mix 3 to 10 parts by weight of solid content.

When forming the easy-adhesion layer, an adhesive resin composition containing a (meth) acrylate having a (meth) acryloyl group in the molecule and / or a (meth) acrylate oligomer as a main component is prepared by using toluene, butyl acetate, or iso. Prepared as a varnish with a solid content of 30 to 50% by diluting it with a solvent such as butanol, ethyl acetate, cyclohexane, cyclohexanone, methylcyclohexanone, hexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether, diethyl ether, and ethylene glycol. To do.

The easy-adhesion layer 2 is formed by applying the above varnish on the cycloolefin resin film 1. The varnish coating method can be selected in a timely manner according to the conditions of the varnish and the coating process. For example, the dip coating method, the air knife coating method, the curtain coating method, the roller coating method, the wire bar coating method, the gravure coating method, and the die coating method. It can be applied by the method or the extrusion coating method.

An easy-adhesion layer can be formed by curing the coating film after applying the varnish. As a curing treatment of the adhesive resin composition having ultraviolet curability, when the varnish contains a solvent, the solvent is removed by drying (for example, at 80 ° C. for 1 minute), and then 500 mW / cm ^{2 to} 3000 mW / cm is used using an ultraviolet irradiator. An example is a procedure of curing by performing ultraviolet treatment with an irradiation intensity of cm ² and a work amount of 50 to 400 mJ / cm ² . An ultraviolet lamp is generally used as an ultraviolet source, and specific examples thereof include a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a xenon lamp, and a metal halide lamp, and when irradiating, even in the air. It may be an inert gas such as nitrogen or argon.

It is preferable to heat during the ultraviolet curing treatment. The curing reaction of the adhesive resin composition proceeds by irradiation with ultraviolet rays, and at the same time, a crosslinked structure is formed. By heating at this time, the formation of a crosslinked structure can be sufficiently promoted even with a low amount of ultraviolet rays, and a desired absorbance ratio can be efficiently achieved. The heating temperature can be set according to the degree of cross-linking, and is preferably 50 ° C to 80 ° C. The heating means is not particularly limited, and a warm air dryer, a radiant heat dryer, heating of a film transport roll, and the like can be appropriately adopted.

The wetting tension on the surface of the easy-adhesion layer 2 is preferably 45 dyn / cm or less, more preferably 44 dyn / cm or less, and even more preferably 40 dyn / cm or less. By setting the wetting tension on the surface of the easy-adhesion layer 2 within the above range, the surface free energy can be reduced and the adhesion with the conductive layer can be further improved. The wetting tension is preferably 35 dyn / cm or more. The wet tension can be measured by using a mixed solution for a wet tension test of Wako Pure Chemical Industries, Ltd. based on the provisions of JIS-K-6768.

The thickness of the easy-adhesion layer is not particularly limited, but is preferably 0.2 μm to 2 μm, more preferably 0.5 μm to 1.5 μm, and even more preferably 0.8 μm to 1.2 μm. .. By setting the thickness of the easy-adhesion layer within the above range, the adhesion can be exhibited at a higher level, and the conductive film can be prevented from breaking due to the loss of flexibility of the easy-adhesion layer.

(Conductive layer)
The conductive layer is preferably formed directly on the easy-adhesion layer formed on at least one surface side of the resin film. The electrical resistivity of the conductive layer may be appropriately set according to the application. For example, in order to sufficiently obtain the electromagnetic wave shielding effect, the sensor function, and the like, the electrical resistivity is preferably 50 μΩcm or less. Copper (Cu) may be included as a constituent material of the conductive layer. Copper has high conductivity that contributes to electromagnetic wave shielding characteristics and sensor functions, is relatively inexpensive, and has excellent cost performance and production efficiency. Elements other than Cu may be contained to the extent of impurities, for example, Fe, Cr, Ti, Si, Nb, In, Zn, Sn, Au, Ag, Co, Cr, Ni, Pb, Pd, Pt, W, Examples thereof include metals such as Zr, Ta, Hf, Mo, Mn, Mg and V. Further, those containing two or more of these metals, alloys containing these metals as main components, and the like can also be used. As a result, the electrical resistivity is sufficiently small and the conductivity is high, so that the electromagnetic wave shielding characteristics and the sensor function can be improved.

The method for forming the conductive layer is not particularly limited, and a conventionally known method can be adopted. Specifically, for example, from the viewpoint of film thickness uniformity and film formation efficiency, vacuum film forming methods such as sputtering method, chemical vapor deposition method (CVD) and physical vapor deposition method (PVD), and ion play The film is preferably formed by a ting method, a plating method (electrolytic plating, non-electrolytic plating), a hot stamping method, a coating method, or the like. Further, a plurality of these film forming methods may be combined, or an appropriate method may be adopted depending on the required film thickness. Of these, the sputtering method and the vacuum film forming method are preferable, and the sputtering method is particularly preferable. As a result, continuous production can be performed by the roll-to-roll manufacturing method, the production efficiency can be improved, and the film thickness at the time of film formation can be controlled, so that an increase in the surface resistance value of the conductive film can be suppressed. In addition, a thin conductive layer having a uniform film thickness and a dense conductive layer can be formed.

The thickness of the conductive layer is preferably 2 to 1000 nm, more preferably 5 to 500 nm, and even more preferably 10 to 220 nm. When the thickness of the conductive layer is within the above range, curling of the conductive film after heating can be suppressed, and resistance can be reduced. In addition, the production efficiency during film formation is increased, the integrated heat quantity during film formation is reduced, and heat wrinkles are less likely to occur on the film.

(Protective layer)
A protective layer may be formed on the outermost surface side (the side opposite to the resin film side) of the conductive layer. It is possible to prevent the conductive layer from being naturally oxidized under the influence of oxygen in the atmosphere. The protective layer is not particularly limited as long as it exhibits a rust preventive effect on the conductive layer, but a metal that can be sputtered is preferable, and Ni, Cu, Ti, Si, Zn, Sn, Cr, Fe, indium, gallium, antimony, and zirconium are preferable. , Magnesium, aluminum, gold, silver, palladium, tungsten, any one or more of the metals selected from the above, or oxides thereof. Ni, Cu, and Ti are hard to be corroded because they form a passivation layer, Si is hard to be corroded because they improve corrosion resistance, and Zn and Cr are hard to be corroded because they form a dense oxide film on the surface. preferable.

As the material of the protective layer, an alloy composed of two kinds of metals can be used from the viewpoint of improving the adhesion with the conductive layer and surely preventing rusting of the conductive layer, but it is composed of three or more kinds of metals. Alloys are preferred. Alloys Examples of alloys composed of three or more kinds of metals include Ni-Cu-Ti, Ni-Cu-Fe, Ni-Cu-Cr, etc. From the viewpoint of rust prevention function and production efficiency, Ni-Cu-Ti is used. preferable. From the viewpoint of improving the adhesion to the conductive layer, an alloy containing the conductive layer is preferable. As a result, oxidation of the conductive layer can be reliably prevented.

Examples of the material of the protective layer include indium-doped tin oxide (ITO), antimony-containing tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), and indium-doped zinc oxide (ATO). IZO) may be included. It is preferable because not only the increase in the initial surface resistance value of the conductive film can be suppressed, but also the increase in the surface resistance value under humidifying heat conditions can be suppressed, and the stabilization of the surface resistance value can be optimized.

The metal oxide is preferably an oxide of SiOx (x = 1.0 to 2.0), copper oxide, silver oxide, titanium oxide or the like, but from the viewpoint of stabilizing the surface resistance value of the conductive film. , SiOx (x = 1.0 to 2.0) is particularly preferable. As a result, the conductive layer is less likely to be corroded. It is also possible to provide a rust preventive effect by forming a resin layer such as an acrylic resin or an epoxy resin on the conductive layer instead of the above-mentioned metals, alloys, oxides and the like.

The film thickness of the protective layer is preferably 1 to 50 nm, more preferably 2 to 30 nm, and preferably 3 to 20 nm. As a result, durability is improved and oxidation can be prevented from the surface layer, so that an increase in the surface resistance value under humidifying heat conditions can be suppressed.

(Hard coat layer)
A hard coat layer 4 may be provided on the surface side of the cycloolefin resin film 1 opposite to the side of the easy-adhesion layer 2 in order to prevent breakage of the resin film 1 and improve handleability. Further, the hard coat layer 4 preferably contains particles in order to prevent blocking between the films and enable production by the roll-to-roll method.

The same adhesive resin composition as the easy-adhesion layer 2 can be preferably used for forming the hard coat layer 4. In order to impart antiblocking property, it is preferable to add particles to the adhesive resin composition. As a result, unevenness can be formed on the surface of the hard coat layer 4, and anti-blocking property can be suitably imparted to the conductive film 10.

As the particles, transparent particles such as various metal oxides, glass, and plastic can be used without particular limitation. For example, crosslinked or uncrosslinked particles composed of inorganic particles such as silica, alumina, titania, zirconia, calcium oxide, polymethylmethacrylate, polystyrene, polyurethane, acrylic resin, acrylic-styrene copolymer, benzoguanamine, melamine, polycarbonate and other polymers. Examples thereof include crosslinked organic particles and silicone particles. As the particles, one kind or two or more kinds can be appropriately selected and used.

The average particle size and the blending amount of the particles can be appropriately set in consideration of imparting surface irregularities and haze. The average particle size is preferably 0.5 μm to 2.0 μm, and the blending amount is preferably 0.2 to 5.0 parts by weight with respect to 100 parts by weight of the solid content of the resin composition.

The thickness of the conductive film of the present embodiment is preferably in the range of 2 to 200 μm, more preferably in the range of 10 to 100 μm, and further preferably in the range of 20 to 60 μm. As a result, the conductive film itself can be made thin, and the thickness when used for an electromagnetic wave shield sheet, a sensor, or the like can be suppressed. Therefore, it is possible to reduce the thickness of the electromagnetic wave shield sheet, the sensor, and the like. Further, when the thickness of the conductive film is within the above range, the mechanical strength can be made sufficient while ensuring the flexibility, and the film is made into a roll to continuously form the easy-adhesion layer, the conductive layer and the like. The forming operation becomes easy and the production efficiency is improved.

(Use of conductive film)
The conductive film of the present embodiment can be applied to various uses, for example, an electromagnetic wave shield sheet, a planar sensor, or the like. The electromagnetic wave shield sheet uses a conductive film, and can be suitably used in the form of a touch panel or the like. The thickness of the electromagnetic wave shield sheet is preferably 20 μm to 300 μm.

The shape of the electromagnetic wave shield sheet is not particularly limited, and the shape seen from the stacking direction (the same direction as the thickness direction of the sheet) is square, circular, triangular, or polygonal, depending on the shape of the object to be installed. It can be selected to an appropriate shape such as a shape.

The surface sensor uses a conductive film, and has a force sensor for load measurement on a user interface such as a touch panel or a controller of a mobile device, a sensing area of an object, for example, an outer surface of an automobile, a robot or a doll. It includes a sensor that senses various physical quantities such as external forces applied to the surface. The planar sensor can be suitably used in the form of a force sensor, a shield, or the like. The thickness of the planar sensor is preferably 20 μm to 300 μm.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the examples, unless otherwise specified, the term "part" means "part by weight".

<Example 1>
(Formation of hard coat layer)
As a material for forming the hard coat layer, 80 parts by weight of DIC Corporation's product name "Unidic ELS-888" and 20 parts by weight of DIC Corporation's product name "Unidic RS28-605" are mixed. The resin composition solution was prepared. The prepared resin composition solution is applied to one surface of a norbornene-based resin film having a thickness of 50 μm (manufactured by Nippon Zeon Corporation, trade name “Zeonoa film”, hereinafter referred to as “COP film”) as a base film. After drying at 80 ° C. for 1 minute, immediately irradiate with ultraviolet rays with an ozone type high-pressure mercury lamp (16 W / cm, 15 cm condensing type, integrated light amount: 200 mJ / cm ² ) to form a hard coat layer with a thickness of 1.0 μm. did.

(Formation of easy adhesion layer)
An ultraviolet curable adhesive resin composition (manufactured by Aika Kogyo Co., Ltd., "Z-844-2L") is applied to the other surface of the COP film, dried at 80 ° C. for 1 minute, and then immediately ozone type high pressure. Ultraviolet irradiation was performed with a mercury lamp (15 cm condensing type, UV intensity 16 W / cm ² , integrated light amount: 200 mJ / cm ² ) to form an easily adherent layer having a thickness of 0.8 μm. The surface temperature of the film transport roll at the time of ultraviolet irradiation was set to 50 ° C., and ultraviolet curing was performed while heating.

(Formation of conductive layer)
Next, a roll around which a long resin film having an easy-adhesion layer formed on the PET film was wound was installed in the sputtering apparatus. Next, the resin film was fed at a film feed speed of 2 m / min, and in an atmosphere of 3.0 × 10 ^-3 Torr composed of 100% by volume of Ar gas, a Cu target material was used, and the sintered body was subjected to a DC magnetron sputtering method. A conductive layer (Cu layer) was formed on the easy-adhesion layer to a thickness of 200 nm, and finally the film was wound to prepare a wound body of the conductive film.

<Example 2>
The same as in Example 1 except that the thickness of the easy-adhesion layer was 0.4 μm, the surface temperature of the film transport roll during ultraviolet irradiation was 75 ° C., and ultraviolet curing was performed while heating to form the easy-adhesion layer. A wound body of a conductive film was prepared in.

<Example 3>
A wound body of a conductive film was produced in the same manner as in Example 2 except that the thickness of the easy-adhesion layer was 0.8 μm.

<Example 4>
A wound body of a conductive film was produced in the same manner as in Example 2 except that the thickness of the easy-adhesion layer was 1.5 μm.

<Example 5>
A wound body of a conductive film was produced in the same manner as in Example 2 except that the thickness of the easy-adhesion layer was 2.2 μm.

<Comparative example 1>
A wound body of a conductive film was produced in the same manner as in Example 1 except that the surface temperature of the film transport roll during ultraviolet irradiation was set to 25 ° C. and ultraviolet curing was performed at room temperature to form an easy-adhesion layer.

<Evaluation>
The produced easy-adhesion layer and conductive film were evaluated as follows. The results of each are shown in Table 1.

(1) Measurement of thickness The thickness of less than 1 μm was measured by observing the cross section of the conductive film using a transmission electron microscope (manufactured by Hitachi, Ltd., product name “H-7650”). The thickness of 1 μm or more was measured using a film thickness meter (Digital Dial Gauge DG-205 manufactured by Peacock).

(2) Adhesion evaluation (conductive layer)
Adhesion was evaluated for each of the samples having a thickness of the conductive layer of 200 nm and 1 μm. A size of 50 mm × 50 mm was cut out from the conductive film, and this was used as a measurement sample to evaluate the adhesion by the cross-cut method based on JIS-K-5600. Use a utility knife or the like to make 11 cuts at 1 mm intervals on the conductive layer surface vertically and horizontally to make a total of 100 grid-shaped squares, and cut the cellophane tape to a length of about 75 mm on the grid. (Registered trademark) (3M, trade name "610-1PK") is pasted, and then the end of the tape is grasped and peeled off in the 60 ° direction in a time of 0.5 to 1.0 seconds, and the conductive layer is peeled off. Was visually confirmed and evaluated. When the number of squares in which the conductive layer remained was 90 or more (residual ratio: 90% or more), it was evaluated as "○", and when it was less than 90 (residual ratio: less than 90%), it was evaluated as "x". ..

For the conductive layer having a thickness of 1 μm, the thickness of the conductive layer (Cu layer) was increased to 1 μm by a plating method, and a conductive film having the conductive layer as a thick film was used as a measurement sample and evaluated by the above procedure. .. When the number of squares in which the conductive layer remained was 60 or more (residual ratio: 60% or more), it was evaluated as "○", and when it was less than 60 (residual ratio: less than 60%), it was evaluated as "x". ..

(3) Adhesion evaluation (easy adhesion layer)
The adhesion of the easy-adhesion layer before forming the conductive layer was evaluated. A size of 50 mm × 50 mm was cut out from the COP film and PET film on which the hard coat layer and the easy adhesion layer were formed, and the adhesion was evaluated by the cross-cut method based on JIS-K-5600 using this as a measurement sample. Using a cutter knife or the like, make 11 cuts at 1 mm intervals on the surface of the easy-adhesion layer, making a total of 100 grid-shaped squares, and cutting them to a length of about 75 mm on the grid-shaped surface. Attach cellophane tape (registered trademark) (3M, trade name "610-1PK"), then grab the end of the tape and peel it off in the 60 ° direction in 0.5 to 1.0 seconds to make the easy-adhesion layer. The peeling state was visually confirmed and evaluated. When the number of squares in which the easy-adhesion layer remains is 90 or more (residual ratio: 90% or more), it is "○", and when it is 80 or more and less than 90 (residual ratio: 80% or more and less than 90%). Was evaluated as “Δ”, and the case where the number was less than 80 (residual ratio: less than 80%) was evaluated as “x”.

(4) Evaluation of scratch resistance of the easy-adhesion layer The scratch resistance of the easy-adhesion layer before forming the conductive layer was evaluated. After placing a melamine sponge (20 mm x 20 mm x 120 mm, manufactured by Lec Co., Ltd., "Geki Ochi-kun") on the surface of the easy-adhesion layer of the COP film and PET film on which the hard coat layer and the easy-adhesion layer are formed, 200 g The film was reciprocated 10 times (distance between the starting point and the turning point: 150 mm) while applying the load of. The melamine sponge was removed, and the presence or absence of scratches on the surface of the easy-adhesion layer was visually evaluated. The case where there was no scratch was evaluated as "◯", the case where the number of scratches was 10 or less was evaluated as "Δ", and the case where there was more than 10 scratches was evaluated as "x".

(5) 180 ° Bending Test A rectangular shape having a size of 10 mm × 100 mm was cut out from the wound body of the conductive film, and this was used as a measurement sample. The sample was cut out so that two types of samples could be obtained: a sample in which the long side of the sample was cut out along the MD direction of the conductive film (MD direction sample) and a sample in which the long side of the sample was cut out along the TD direction (TD direction sample). It was. For both measurement samples, overlap the ends of the long sides so that the base film side is on the inside and the conductive layer side is on the outside, so that the folding angle of the central crease is about 180 ° (at the crease). The measurement sample was bent (so that there were no gaps). At this time, "○" indicates that the film did not break in either the MD direction sample or the TD direction sample, "Δ" indicates that the film broke in one film, and the film rupture occurred in both films. The case where it occurred was evaluated as "x".

(Results and discussion)
In all of the conductive films of the examples, the adhesiveness between the conductive layer and the easy-adhesion layer was good. On the other hand, in Comparative Example 1, all the squares of the conductive layer were peeled off, and the adhesion was insufficient. It is presumed that this is because the formation of the crosslinked structure in the easy-adhesion layer was insufficient due to the fact that the easy-adhesion layer was not heated during UV curing, and the film strength became low. This can be seen from the fact that in Comparative Example 1, the scratch resistance and adhesion of the easy-adhesion layer are lowered, and the film strength is lowered. In Example 5 in which the thickness of the easy-adhesion layer was 2.2 μm, the adhesion and bending resistance of the easy-adhesion layer were slightly reduced although there was no practical problem, so that the thickness of the easy-adhesion layer was 2 μm or less. It can be said that it is preferable.

1 Cycloolefin resin film 2 Easy adhesion layer 3 Conductive layer 4 Hard coat layer

Claims (6)

An easy-adhesion layer, which is a cured film of the adhesive resin composition, and a conductive layer containing copper are provided on one surface side of the cycloolefin resin film in this order.
The easy-adhesion layer contains nanosilica fine particles and contains
The average particle size of the nanosilica fine particles is 100 to 500 nm (excluding 100 nm).
A hard coat layer is provided on the other surface side of the cycloolefin resin film.
A conductive film having 60% or more of squares that did not peel off after a grid peeling test on the conductive layer having a thickness of 1 μm. The conductive film according to claim 1, wherein the adhesive resin composition contains at least one of a (meth) acrylate monomer and a (meth) acrylate oligomer. The conductive film according to claim 1 or 2, wherein the adhesive resin composition has ultraviolet curability. The conductive film according to any one of claims 1 to 3, wherein the thickness of the easy-adhesion layer is 0.2 μm to 2 μm. The conductive film according to any one of claims 1 to 4, wherein the thickness of the conductive layer is 2 nm to 1000 nm. The conductive film according to any one of claims 1 to 5, wherein the hard coat layer contains particles.

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