JP2020097761A - Method for producing conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a conductive film capable of suppressing the generation of wrinkles in a resin film even when forming a relatively thick conductive layer.
SOLUTION: Step A of forming a first conductive layer on one surface of a resin film, step B of adhering a protective film on the first conductive layer, and the other surface of the resin film while feeding the resin film. And a step C of forming a second conductive layer having a thickness of 80 nm or more and 300 nm or less by a sputtering method.
[Selection diagram] Figure 1

Description

The present invention relates to a method of manufacturing a conductive film.

Conventionally, a conductive film having conductive layers formed on both sides of a resin film has been used for flexible circuit boards, electromagnetic wave shielding films, flat panel displays, touch sensors, non-contact type IC cards, solar cells, etc. Reference 1). The main function of the conductive film is electric conduction, and the composition and thickness of the conductive layer provided on the surface of the polymer film are appropriately selected so as to obtain electric conductivity suitable for the purpose of use.

JP, 2011-82848, A

In recent years, in order to improve the functions of devices and expand their applications, lower resistance of conductive layers may be required. Generally, the resistance of the conductive layer can be reduced by increasing the thickness of at least one of the conductive layers. However, when a thick conductive layer is formed by a sputtering method, wrinkles may occur on the resin film, which is one of the causes of lowering productivity and reliability.

An object of the present invention is to provide a method for producing a conductive film, which can suppress the generation of wrinkles in a resin film even when forming a relatively thick conductive layer.

The inventors of the present invention have made extensive studies to solve the above problems, and have found that the above object can be achieved by adopting the following configuration, and have completed the present invention.

The present invention provides, in one embodiment,
Step A of forming a first conductive layer on one surface of the resin film,
Step B of attaching a protective film on the first conductive layer, and Step C of forming a second conductive layer having a thickness of 80 nm or more and 300 nm or less on the other surface of the resin film by a sputtering method while feeding the resin film.
The present invention relates to a method for producing a conductive film containing:

In the manufacturing method, the protective film is attached to the first conductive layer formed on one surface of the resin film, and then the thick second conductive layer is formed on the other surface of the resin film. In other words, the protective film functions as a reinforcing material for the resin film when the second conductive layer is formed, so that the occurrence of wrinkles in the resin film can be suppressed.

In the step A, it is preferable that the first conductive layer is formed by a sputtering method. A homogeneous conductive layer can be efficiently formed. In addition, the steps A to C can be continuously performed by a roll-to-roll method, and the yield can be improved.

The thickness of the first conductive layer is preferably 80 nm or more and 300 nm or less. This makes it possible to form a thick conductive layer on both sides and to achieve low resistance and high functionality of the conductive film.

The thickness of the protective film is preferably 20 μm or more and 200 μm or less. By setting the thickness of the protective film within this range, it is possible to exhibit sufficient resin film reinforcing property while maintaining the handling property.

In the step C, the total power density represented by the following formula in the sputtering method is preferably 1500 kW/m ² or less.
Total power density=N×T×P
(In the formula, N is the number of process repetitions, T is the number of targets per process, and P is the power density [kW/m ² ] per target.)

By setting the total power density during the sputtering in the step C to be equal to or lower than the predetermined value, the load on the resin film can be reduced and the generation of wrinkles can be suppressed at a higher level. Further, in order to form a thick conductive layer, it is possible to employ a procedure of performing sputtering with a high power density a few times or a procedure of performing sputtering with a low power density a number of times. In any of the procedures, by controlling the total power density obtained by the above formula within a predetermined range, it is possible to produce a conductive film with high production efficiency while suppressing wrinkles in the resin film.

In the step C, the tensile stress in the MD direction of the resin film is preferably 1 MPa or more. By applying a predetermined tensile stress in the MD direction of the resin film when forming the second conductive layer, it is possible to further reduce the occurrence of wrinkles in the resin film.

It is a typical sectional view of a conductive film concerning one embodiment of the present invention. It is a conceptual diagram explaining the structure of the vacuum film-forming apparatus which concerns on one Embodiment of this invention.

An embodiment of the method for producing a conductive film of the present invention will be described below with reference to the drawings. However, in some or all of the drawings, parts unnecessary for description are omitted, and there are parts illustrated in an enlarged or reduced form for ease of description. The terms indicating the positional relationship such as the upper and lower sides are used merely for facilitating the description, and are not intended to limit the configuration of the present invention at all.

«First embodiment»
<Method for producing conductive film>
The method for producing a conductive film according to the present embodiment includes a step A of forming a first conductive layer on one surface of a resin film, a step B of attaching a protective film on the first conductive layer, and the resin film. It includes a step C of forming a second conductive layer having a thickness of 80 nm or more and 300 nm or less on the other surface of the resin film while unwinding by a sputtering method.

FIG. 1 is a schematic cross-sectional view of a conductive film obtained by the method for manufacturing a conductive film of this embodiment. The conductive film 100 shown in FIG. 1 includes a resin film 1, a first conductive layer 21 formed on one surface of the resin film 1, and a second conductive layer 22 formed on the other surface of the resin film 1. (Hereinafter, when the first conductive layer and the second conductive layer are not distinguished from each other, they may be simply referred to as “conductive layer”). Further, in the present embodiment, the first protective film 31 is arranged on the side of the first conductive layer 21 opposite to the resin film 1, and the second protective film 32 is arranged on the side of the second conductive layer 22 opposite to the resin film 1. It is arranged (hereinafter, when the first protective film and the second protective film are not distinguished from each other, they may be simply referred to as “protective film”).

<<Process A>>
In step A, the first conductive layer 21 is formed on one surface of the resin film 1.

(Resin film)
The resin film 1 is not particularly limited as long as it can ensure the insulating property, and various plastic films are used. Examples of the material for the resin film include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and polyethylene naphthalate (PEN), polyimide resins such as polyimide (PI), polyethylene (PE), polypropylene (PP). ) Etc. polyolefin resin, acetate resin, polyether sulfone resin, polycarbonate resin, polyamide resin, cycloolefin resin, (meth)acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene Examples of the resin include polyvinyl resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins. Among them, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) and polyimide resins such as polyimide (PI) are preferable from the viewpoints of heat resistance, durability, flexibility, production efficiency, cost and the like. preferable. Particularly, polyethylene terephthalate (PET) is preferable from the viewpoint of cost performance.

The resin film is subjected to an etching treatment or undercoating treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, or oxidation on the surface in advance to improve adhesion with the conductive layer formed on the resin film. You may make it secure. In addition, before forming the conductive layer, the surface of the resin film may be removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like, if necessary.

The thickness of the resin film is preferably in the range of 2 to 300 μm, more preferably in the range of 10 to 250 μm, and even more preferably in the range of 20 to 200 μm. In general, a thicker resin film is desirable because it is less likely to be affected by heat shrinkage during heating. However, it is desirable to reduce the thickness of the resin film to some extent as electronic parts are made more compact. On the other hand, when the thickness of the resin film is too thin, the moisture permeability and the permeability of the resin film increase, and moisture, gas, etc. are transmitted, and the conductive layer is easily oxidized. Therefore, in the present embodiment, the conductive film itself can be thinned by reducing the thickness of the resin film while having a certain thickness, and it is possible to suppress the thickness when used for an electromagnetic wave shielding sheet, a sensor, or the like. Becomes Therefore, it is possible to reduce the thickness of the electromagnetic wave shield sheet and the sensor. Further, when the thickness of the resin film is within the above range, mechanical strength is sufficient while ensuring flexibility of the resin film, and an operation of continuously forming a base layer or a conductive layer by rolling the film. Is possible.

(First conductive layer)
The first conductive layer 21 provided on one surface side of the resin film 1 preferably has an electric resistivity of 100 μΩcm or less in order to sufficiently obtain an electromagnetic wave shielding effect, a sensor function, and the like. The constituent material of the first conductive layer 21 is not particularly limited as long as it satisfies such an electrical resistivity and has conductivity. For example, Cu, Al, Fe, Cr, Ti, Si, Nb, In , Zn, Sn, Au, Ag, Co, Cr, Ni, Pb, Pd, Pt, W, Zr, Ta, Hf, Mo, Mn, Mg, and V are preferably used. Further, those containing two or more kinds of these metals, and alloys and oxides containing these metals as main components can also be used. Among these conductive compounds, it is preferable to contain Cu and Al from the viewpoints of high conductivity that contributes to electromagnetic wave shielding properties and sensor functions and relatively low price. In particular, from the viewpoint of cost performance and production efficiency, it is preferable that Cu is contained, but elements other than Cu may be contained as much as impurities. As a result, the electrical resistivity is sufficiently small and the electrical conductivity is high, so that the electromagnetic wave shielding property and the sensor function can be improved.

The thickness of the first conductive layer 21 is preferably 10 nm or more and 300 nm or less. The lower limit value of the thickness of the first conductive layer 21 is more preferably 20 nm, further preferably 80 nm. On the other hand, the upper limit value of the thickness of the first conductive layer 21 is more preferably 260 nm, further preferably 240 nm. When the thickness of the first conductive layer 21 exceeds the above upper limit, curling of the conductive film after heating is likely to occur or it is difficult to thin the device. If the thickness is smaller than the above lower limit value, the surface resistance value of the conductive film tends to be high under the humidification heat condition and the target humidification heat reliability cannot be obtained, or the strength of the conductive layer is reduced, resulting in a pattern wiring Peeling may occur.

The method for forming the first conductive layer 21 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, a vacuum film formation method such as a sputtering method, a chemical vapor deposition method (CVD), a physical vapor deposition method (PVD), or an ion plating method. The film is preferably formed by a coating method, a plating method (electrolytic plating, electroless plating), a hot stamping method, a coating method, or the like. Further, a plurality of these film forming methods may be combined, and an appropriate method may be adopted depending on the required film thickness. Among them, 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, 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. Further, a dense conductive layer which is thin and has a uniform film thickness can be formed. When vacuum film formation (particularly, sputtering film formation) is performed while continuously feeding the film by using the roll-to-roll manufacturing method, the method for forming the second conductive layer described below can be preferably adopted. ..

(Protective layer)
The protective layer can be formed, for example, on the outermost surface side of the first conductive layer 21 in order to prevent the first conductive layer 21 from naturally oxidizing under the influence of oxygen in the atmosphere (not shown). ). The protective layer can be typically formed by mounting a target for forming the protective layer downstream of a metal material source (target) for forming the first conductive layer 21 and forming a film by sputtering.

The protective layer is not particularly limited as long as it exhibits the rust preventing effect of the first conductive layer 21, but a metal that can be sputtered is preferable, and Ni, Cu, Ti, Si, Zn, Sn, Cr, Fe, indium, gallium, At least one metal selected from the group consisting of antimony, zirconium, magnesium, aluminum, gold, silver, palladium and tungsten, or an oxide thereof is used. Ni, Cu, and Ti are less likely to be corroded because they form a passivation layer, Si is less likely to be corroded because of improved corrosion resistance, and Zn and Cr are metals that are less susceptible to corrosion because they form a dense oxide film on the surface. preferable.

As a material of the protective layer, an alloy composed of two kinds of metals can be used from the viewpoint of ensuring adhesion with the first conductive layer 21 and reliably preventing rust of the first conductive layer 21, but 3 Alloys of one or more metals are preferred. Examples of alloys composed of three or more kinds of metals include Ni-Cu-Ti, Ni-Cu-Fe, and Ni-Cu-Cr. Ni-Cu-Ti is Ni-Cu-Ti from the viewpoint of rust prevention function and production efficiency. preferable. From the viewpoint of ensuring adhesiveness with the first conductive layer 21, an alloy containing a material for forming the first conductive layer 21 is preferable. Thereby, the oxidation of the first conductive layer 21 can be surely 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 ( IZO) may be included. It is preferable because not only the initial increase in the surface resistance value of the conductive film can be suppressed, but also the increase in the surface resistance value under the humidified heat condition can be suppressed and the stabilization of the surface resistance value can be optimized.

The metal oxide is preferably an oxide such as SiOx (x=1.0 to 2.0), copper oxide, silver oxide, or titanium oxide. 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 first conductive layer 21 instead of the metal, alloy, oxide or the like described above.

The 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 the increase in surface resistance value under humidified heat conditions can be suppressed.

<<Process B>>
In step B, the first protective film 31 is attached onto the first conductive layer 21. It is preferable to bond the first protective film 31 immediately after the first conductive layer 21 is formed (in the same line as the first conductive layer forming line). As a result, it is possible to reduce the oxidation and scratches of the first conductive layer 21.

(Protective film)
The surface of the first protective film 31 on the side in contact with the first conductive layer 21 has adhesiveness. The material and structure of the first protective film 31 are not particularly limited, but it is desirable to have a base material layer containing a polyolefin resin and an adhesive layer containing a thermoplastic elastomer. As a material for forming the pressure-sensitive adhesive layer, a known pressure-sensitive adhesive such as a removable acrylic pressure-sensitive adhesive can also be used.

The polyolefin resin forming the base material layer is not particularly limited, and examples thereof include propylene-based polymers such as polypropylene or block-based or random-based propylene components and ethylene components; low density, high density, linear low density polyethylene and the like. Ethylene-based polymer; olefin-based polymers such as ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-methyl methacrylate copolymers, and other olefin-based polymers of ethylene components and other monomers. These polyolefin resins may be used alone or in combination of two or more.

The base material layer 1 contains an olefin resin as a main component, but for the purpose of preventing deterioration, for example, a light stabilizer such as an antioxidant, an ultraviolet absorber, a hindered amine light stabilizer, an antistatic agent, and the like. In addition, for example, fillers such as calcium oxide, magnesium oxide, silica, zinc oxide, and titanium oxide, additives such as pigments, anti-corrosion agents, lubricants, and anti-blocking agents can be appropriately mixed.

The thickness of the base material layer 1 is not particularly limited, but is preferably 20 μm or more and 200 μm or less, more preferably 30 μm or more and 150 μm or less, and further preferably 40 μm or more and 100 μm or less. Further, the base material layer 1 may be a single layer or a multilayer including two or more layers.

If necessary, the surface of the base material layer 1 opposite to the surface on which the adhesive layer is provided is subjected to surface treatment such as corona discharge treatment, flame treatment, plasma treatment, sputter etching treatment, and undercoat treatment such as primer treatment. You can also

As the thermoplastic elastomer forming the adhesive layer 2, those used as the base polymer of the adhesive such as styrene-based elastomer, urethane-based elastomer, ester-based elastomer, and olefin-based elastomer can be used without particular limitation. More specifically, styrene/butadiene/styrene (SBS), styrene/isoprene/styrene (SIS), styrene/ethylene-butylene copolymer/styrene (SEBS), styrene/ethylene/propylene copolymer/styrene (SEPS) ) Etc. ABA type block polymers; styrene/butadiene (SB), styrene/isoprene (SI), styrene/ethylene/butylene copolymer (SEB), styrene/ethylene/propylene copolymer (SEP), etc. AB block polymer of styrene; Random styrene copolymer such as styrene/butadiene rubber (SBR); ABC/styrene olefin such as styrene/ethylene/butylene copolymer/olefin crystal (SEBC) Crystalline block polymer; CBC type olefin crystalline block polymer such as olefin crystal/ethylene-butylene copolymer/olefin crystal (CEBC); ethylene-α olefin, ethylene-propylene-α olefin, propylene-α Examples thereof include olefin elastomers such as olefins, and hydrogenated products thereof. These thermoplastic elastomers may be used alone or in combination of two or more.

In forming the adhesive layer 2, if necessary, for example, a softening agent, an olefin-based resin, a silicone-based polymer, a liquid acrylic copolymer, a phosphoric acid is added to the thermoplastic elastomer for the purpose of controlling the adhesive property. Ester compounds, tackifiers, antioxidants, hindered amine light stabilizers, UV absorbers, and other additives such as fillers and pigments such as calcium oxide, magnesium oxide, silica, zinc oxide, titanium oxide, etc. Can be blended appropriately.

The thickness of the pressure-sensitive adhesive layer 2 is not particularly limited and may be appropriately determined depending on the required adhesive force and the like, but is usually about 0.1 to 50 μm, preferably 0.2 to 40 μm, and further It is preferably 0.3 to 20 μm.

The surface of the adhesive layer 2 needs to be subjected to surface treatment such as corona discharge treatment, ultraviolet ray irradiation treatment, flame treatment, plasma treatment and sputter etching treatment for the purpose of controlling adhesiveness and workability of sticking. It can also be applied accordingly. Furthermore, the adhesive layer 2 can be protected by temporarily attaching a separator or the like to the adhesive layer 2 until it is put into practical use, if necessary.

Further, a release layer for imparting releasability can be formed on the surface of the base material layer opposite to the surface on which the adhesive layer is attached, if necessary. The release layer may be formed together with the base material layer and the adhesive layer by co-extrusion or may be formed by coating.

When the release layer is formed by co-extrusion, it is preferable to use a mixture of two or more kinds of polyolefin resins. By using a mixture of two or more types of polyolefin-based resins, the compatibility of the two types of polyolefin-based resins can be controlled, so that an appropriate surface roughness can be formed and appropriate release properties can be imparted. is there. When the release layer is formed by coextrusion, its thickness is usually about 1 to 50 μm, preferably 2 to 40 μm, and more preferably 3 to 20 μm.

As the release agent used for forming the release layer by coating, a release agent that can impart releasability can be used without particular limitation. For example, the release agent may be a silicone-based polymer or a long-chain alkyl-based polymer. The release agent may be a solvent-free type, a solvent type dissolved in an organic solvent, or an emulsion type emulsified in water, but the solvent type or emulsion type release agent stably forms the release layer 3 It can be attached to the base material layer 1. Besides, examples of the releasing agent include ultraviolet curable ones. Specific examples of the release agent include Pyroil (manufactured by Yatsusha Oil and Fat Co., Ltd.) and Shin-Etsu Silicone (manufactured by Shin-Etsu Chemical Co., Ltd.).

The thickness of the release layer 3 is not particularly limited, but as described above, it is usually about 1 to 1000 nm, more preferably 5 to 500 nm, and particularly 10 to 100 nm because it has a large contamination reducing effect when formed into a thin film. Preferably.

<<Process C>>
In step C, a second conductive layer having a thickness of 80 nm or more and 300 nm or less is formed on the other surface of the resin film 1 by a sputtering method while feeding the resin film 1. Thus, the protective film 31 functions as a reinforcing material for the resin film 1 when the second conductive layer 22 is formed, and thus the wrinkles of the resin film 1 can be suppressed. Depending on the thickness of the second conductive layer, the step C, which is a sputtering step, is not limited to once and may be performed twice or more times. Hereinafter, the properties of the second conductive layer and the film forming procedure by the sputtering method will be described.

As the constituent material and the electrical resistivity of the second conductive layer 22, the same materials as those of the first conductive layer 21 can be suitably adopted.

The thickness of the second conductive layer 22 is 80 nm or more and 300 nm or less from the viewpoint of reducing resistance and thinning. The lower limit value of the thickness of the second conductive layer 22 is preferably 90 nm, more preferably 100 nm. On the other hand, the upper limit of the thickness of the second conductive layer 22 is preferably 280 nm, more preferably 250 nm. The thicknesses of the conductive layers on both sides may be the same or different.

The absolute value of the difference between the thickness of the first conductive layer 21 and the thickness of the second conductive layer 22 is preferably 5 nm or less, more preferably 3 nm or less. By making the thicknesses of the conductive layers on both sides close to each other, the stress generated in the conductive layers is offset, and curling of the conductive film and peeling of the conductive layers can be prevented.

(Structure of film forming apparatus)
The second conductive layer 22 is preferably formed by the roll-to-roll method while the resin film 1 is being fed. The film formation of the second conductive layer by the roll-to-roll method is performed using a winding type vacuum film forming apparatus 300 as schematically shown in FIG. The vacuum film forming apparatus 300 includes a pay-out roll 301 and a take-up roll 302, and a film-forming roll 310 and carry rolls 303 and 304 in a film carrying path between the pay-out roll 301 and the take-up roll 302. The number of transport rolls is not particularly limited. Each of the transport rolls may be a free rotation type or a drive rotation type. From the viewpoint of controlling the tensile stress in the MD direction at the film formation location, at least one of the transport rolls between the film formation roll 310 and the take-up roll 302 is preferably a drive rotation roll. Further, a drive rotation roll may be arranged between the delivery roll 301 and the film formation roll 310. In addition, the tensile stress in the MD direction at the film forming location refers to the tension between the film forming roll and the drive roll closest to the film forming roll on the film transport path. The drive roll may be a single drive rotation roll or a nip roll that sandwiches the film with two rolls as a pair.

Further, from the viewpoint of controlling the tensile stress at the film forming location, it is preferable that the vacuum film forming apparatus be provided with a tensile stress detecting means such as a tension pickup roll or a dancer roll in the transfer path. Further, from the viewpoint of stabilizing the transport of the film, it is preferable to have a tensile stress control mechanism so that the tensile stress can be controlled so as to be constant at the film formation location. The tensile stress control mechanism, when the tensile stress detected by the tensile stress detecting means such as the tension pickup roll is higher than a set value, the driving rotary roll located on the downstream side of the conveying path with respect to the tensile stress detecting means. When the peripheral speed is reduced and the tensile stress is lower than the set value, feedback is provided to increase the peripheral speed of the drive rotating roll.

From the viewpoint of independently controlling the tensile stress at the film forming location and the film winding stress at the winding roll 302, the film transport path between the film forming roll 310 and the winding roll 302 is provided with a tension cutting means. It is preferable. Further, from the viewpoint of independently controlling the tensile stress at the film forming location and the unrolling stress from the unrolling roll 301, a tension cut means may be provided in the film transport path between the unrolling roll 301 and the film forming roll 310. preferable.

As the tension cutting means, a suction roll, a roll group arranged such that the film transport path has an S shape, or the like can be used in addition to the nip roll. Further, an appropriate tensile stress detecting means such as a tension pickup roll is arranged in the conveyance path between the tension cutting means and the winding roll 302, and the winding stress is kept constant by an appropriate tensile stress control mechanism. The rotation torque of the roll 302 is preferably adjusted. In this way, by independently controlling the tensile stress and the winding stress and/or the unwinding stress at the film forming portion, the winding state is poor due to the small winding stress, and the film due to the large winding stress It is possible to prevent the occurrence of problems such as blocking.

It is preferable that the film forming roll 310 is configured to be temperature-adjustable. As means for controlling the temperature of the roll, a configuration in which a heating medium (and a refrigerant) can be circulated inside the roll, a configuration in which a heating means such as an electric heater is provided in the roll, and a roll from the outside of the roll by a heating means such as an infrared heater A configuration in which the surface can be heated is included. A target 320 is mounted in the vicinity of the film forming roll, and metal atoms vaporized from the target 320 are deposited on the substrate to form a film. The number of targets 320 is not particularly limited and can be appropriately set in consideration of the film quality and productivity of the conductive layer, and may be one as shown in FIG. 2 or plural. When using a plurality of targets, they may be installed sequentially from the upstream side to the downstream side of the line.

(Film forming conditions)
The laminated body L of the resin film 1, the first conductive layer 21, and the protective film 31 is unrolled from the unrolling roll 301 and continuously passed through the plural transport rolls 303 and 304 and the film forming roll 310 so as not to loosen. Be transported. The conductive film 100 on which the second conductive layer 22 is vacuum-deposited on the film forming roll 310 is wound by the winding roll 302.

The tensile stress in the MD direction of the resin film 1 at the film forming location is preferably 1 MPa or more, more preferably 1 MPa or more and 3 MPa or less, and further preferably 1.5 MPa or more and 2.5 MPa or less. By setting the tensile stress within the above range, the generation of wrinkles can be suppressed. If the tensile stress is too small, wrinkles are likely to occur, and if it is too large, the resin film 1 itself may be deformed.

The temperature of the film forming roll 310 during film formation of the second conductive layer 22 is preferably 40° C. to 150° C., more preferably 50° C. to 140° C., and further preferably 60° C. to 130° C. preferable. When the temperature of the film forming roll is excessively low, the temperature difference between the contact surface side of the resin film 1 with the film forming roll and the film forming surface side becomes large, that is, since the temperature distribution in the film thickness direction becomes large, It is presumed that wrinkles are likely to occur on the resin film 1. On the other hand, if the temperature of the film-forming roll is excessively high, it is presumed that wrinkles are likely to occur because the thermal deformation of the film on the film-forming roll becomes large.

Other film forming conditions are not particularly limited. For example, when the first conductive layer 21 made of copper is formed by a sputtering method, copper (preferably oxygen-free copper) is used as a target, and first, a sputtering apparatus is used. The internal vacuum degree (ultimate vacuum degree) is preferably evacuated to 1×10 ⁻³ Pa or less to obtain an atmosphere in which impurities such as water and organic gas generated from the resin film in the sputtering apparatus are removed. preferable.

Into the sputtering apparatus thus evacuated, an inert gas such as Ar was introduced, while the resin film was conveyed under application of tensile stress in the above range, the film forming roll temperature was adjusted to the temperature in the above range, Sputter film formation is performed under reduced pressure. The pressure during film formation is preferably 0.05 Pa to 1.0 Pa, more preferably 0.1 Pa to 0.7 Pa. If the film formation pressure is too high, the film formation rate tends to decrease, and conversely, if the pressure is too low, the discharge tends to be unstable.

The transport speed of the film and the power density per target can be set in consideration of the film quality and film thickness of the conductive layer, production efficiency, and the like. The transport speed of the film is preferably 2 m/min or more and 20 m/min or less, more preferably 3 m/min or more and 18 m/min or less. The power density per target is preferably 20 kW/m ² or more and 100 kW/m ² or less, and more preferably 25 kW/m ² or more and 90 kW/m ² or less.

In Step C, the total power density represented by the following formula in the sputtering method is preferably not more than 1500 kW / ^{m 2,} and more preferably 1200 kW / ^{m 2} or less.
Total power density=N×T×P
(In the formula, N is the number of process repetitions, T is the number of targets per process, and P is the power density [kW/m ² ] per target.)

By setting the total power density during the sputtering in the step C to be equal to or lower than the predetermined value, the load on the resin film can be reduced and the generation of wrinkles can be suppressed at a higher level. Further, in order to form a thick conductive layer, it is possible to employ a procedure of performing sputtering with a high power density a few times or a procedure of performing sputtering with a low power density a number of times. In any of the procedures, by controlling the total power density obtained by the above formula within a predetermined range, it is possible to produce a conductive film with high production efficiency while suppressing wrinkles in the resin film. Considering the productivity, it is preferably 80 kW/m ² or more, more preferably 100 kW/m ² or more.

<<Process D>>
In the present embodiment, following the step C, a step D of attaching the second protective film 32 onto the second conductive layer 22 may be further included. As the second protective film 32, one having the same configuration as the first protective film 31 can be preferably adopted. Similar to the bonding of the first protective film 31, from the viewpoint of reducing the oxidation, scratches, etc. of the second conductive layer 22, immediately after the second conductive layer 22 is formed (same as the second conductive layer forming line). It is preferable to attach the second protective film 32 (in the line). By going through this step D, a conductive film with a protective film in which a conductive layer and a protective film are sequentially laminated on both surfaces of a resin film can be manufactured.

When the conductive film is incorporated into various devices, the protective film on one side or both sides is usually peeled off and used depending on the application.

(Conductive film)
The initial surface resistance value R1 of the conductive film 100 is preferably 0.001 Ω/□ to 10.0 Ω/□, more preferably 0.01 Ω/□ to 7.5 Ω/□, and more preferably 0.1. More preferably, it is 1Ω/□ to 5.0Ω/□. This makes it possible to provide a practical conductive film with excellent production efficiency.

The total thickness of the conductive film 100 is preferably in the range of 2 to 300 μm, more preferably in the range of 10 to 250 μm, and further preferably in the range of 20 to 200 μm. As a result, it is possible to reduce the resistance of the conductive film and also reduce the thickness of the conductive film, and it is possible to suppress the thickness when used in an electromagnetic wave shielding sheet, a sensor, or the like. Therefore, it is possible to reduce the thickness of the electromagnetic wave shield sheet and the sensor. Furthermore, when the thickness of the conductive film is within the above range, mechanical strength can be sufficient while ensuring flexibility, and the film is rolled to continuously form the Si-containing layer and the conductive layer. The forming operation becomes easy and the production efficiency is improved.

The conductive film may be wound in a roll shape from the viewpoint of transportability and handling. By continuously forming the base layer and the conductive layer on the resin film by the roll-to-roll method, the conductive film can be efficiently manufactured.

(Use of conductive film)
The conductive film can be applied to various uses, and can be applied to, for example, an electromagnetic wave shield sheet, a planar sensor, and 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 to 200 μm. When the protective film is attached, it can be used after peeling off the protective film.

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 rectangular, circular, triangular, or polygonal depending on the shape of the object to be installed. A suitable shape such as a shape can be selected.

The planar sensor uses a conductive film and includes a sensor for sensing various physical quantities in addition to user interface applications such as a touch panel of a mobile device and a controller. The thickness of the planar sensor is preferably 20 to 200 μm.

«Second embodiment»
(Underlayer)
In the present embodiment, the conductive film 100 has a base layer (not shown) on either one of the resin film 1 and the first conductive layer 21 and between the resin film 1 and the second conductive layer 22. You may have it. By providing an underlayer according to the purpose such as adhesion of the conductive layer to the resin film, imparting strength to the conductive film, and control of electrical characteristics, the conductive film can be made highly functional. The base layer is not particularly limited, and examples thereof include an easy-adhesion layer, a hard coat layer (including those functioning as an anti-blocking layer, etc.), a dielectric layer, and the like.

(Easy adhesion layer)
The easy-adhesion layer is a cured film of the adhesive resin composition. The easy-adhesion layer has good adhesion to the conductive layer.

As the adhesive resin composition, one having sufficient adhesiveness and strength as a cured film after formation of the easy-adhesion layer can be used without particular limitation. Examples of the resin used include thermosetting resin, thermoplastic resin, ultraviolet curable resin, electron beam curable resin, two-component mixed resin, and mixtures thereof. Among these, curing treatment by ultraviolet irradiation is also included. Therefore, an ultraviolet curable resin that can efficiently form an easy-adhesion layer by a simple processing operation is preferable. By containing 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 upon curing is preferable. When the cross-linking structure in the easy-adhesion layer is promoted, the inner structure of the film, which was gradual until then, is strengthened and the film strength is improved. It is presumed that such improvement in film strength contributes to improvement in adhesion.

The adhesive resin composition preferably contains at least one of a (meth)acrylate monomer and a (meth)acrylate oligomer. This facilitates the formation of a crosslinked structure due to the C═C double bond contained in the acryloyl group, and can efficiently improve the film strength. In addition, in this specification, (meth)acrylate means an acrylate or a methacrylate.

The (meth)acrylate monomer and/or 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 trimethylolpropane tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, trimethylolpropane tetra(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-mentioned (meth)acrylates, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, or a mixture thereof is used in terms of abrasion resistance and curability. Especially preferred.

A urethane acrylate oligomer can also be used. The urethane (meth)acrylate oligomer is obtained by reacting a polyol with a polyisocyanate and then reacting with a (meth)acrylate having a hydroxyl group, or after reacting a polyisocyanate with a (meth)acrylate having a hydroxyl group. Examples thereof include, but are not limited to, a method of reacting a polyol, a method of reacting a polyisocyanate, a polyol, and a (meth)acrylate having a hydroxyl group.

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

Examples of the polyisocyanate include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 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 decreases and the adhesiveness of the conductive layer is likely to decrease, so 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-acryloyloxypropyl(meth)acrylate, pentaerythritol tri(meth)acrylate and the like. The above-mentioned (meth)acrylate monomer component and/or (meth)acrylate oligomer component may be used alone or in combination of two or more kinds.

The UV-curable adhesive resin composition of the present embodiment has improved anti-blocking properties by blending a (meth)acrylic group-containing silane coupling agent. Examples of the (meth)acrylic group-containing silane coupling agent include 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, Examples thereof include 3-methacryloxypropyltriethoxysilane, and examples of commercially available products include KR-513 and KBM-5103 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.).

The amount of the silane coupling agent is 0.1 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 adhesiveness with the conductive layer is improved and the physical properties of the coating film can be maintained.

The easy-adhesion layer of the present embodiment may contain nano silica fine particles. As the nano silica fine particles, an organo silica sol synthesized from alkylsilane or nano silica synthesized by plasma arc can be used. Examples of commercially available products include PL-7-PGME (manufactured by Fuso Kagaku, trade name) for the former, and SIRMIBK15WT%-M36 (manufactured by CIK Nanotech, trade name) for the latter. The compounding ratio of the nano silica fine particles is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the total weight of the (meth)acrylate monomer and/or acrylate oligomer having a (meth)acryloyl group and the silane coupling agent, and preferably 5 to 10 parts by weight. More preferably parts by weight. When the content is at least the lower limit, surface irregularities are formed and anti-blocking properties can be imparted, and roll-to-roll production becomes possible. When the content is at most the upper limit, it is possible to prevent the decrease in the adhesion to the conductive layer.

The average particle size of the nano silica fine particles is preferably 100 to 500 nm. If the average particle size is less than 100 nm, the amount of addition necessary to form irregularities on the surface is large, and thus adhesion to the conductive layer cannot be obtained, whereas if it exceeds 500 nm, the irregularities on the surface become large and pinholes are formed. The problem occurs.

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-hydroxycyclohexyl phenyl 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-propan-1-one, 2-hydroxy-2-methyl-1-(4-isopropylphenyl)propan-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, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, monoacylphosphine oxides such as 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.

From the viewpoints of curability of the resin, light stability, compatibility with the resin, low volatility, and low odor, an alkylphenone-based photopolymerization initiator is preferable, and 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1 -Phenyl-propan-1-one, (2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 1 -[4-(2-Hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one is more preferable, and as commercially available products, Irgacure 127, 184, 369, 651, 500, 891, 907. , 2959, Darocure 1173, TPO (manufactured by BASF Japan Ltd., trade name), etc. The photopolymerization initiator is a (meth)acryloyl group-containing (meth)acrylate monomer and/or acrylate oligomer with respect to 100 parts by weight. The solid content is 3 to 10 parts by weight.

At the time of forming the easy-adhesion layer, an adhesive resin composition containing (meth)acrylate and/or (meth)acrylate oligomer having a (meth)acryloyl group in the molecule as a main component is mixed with toluene, butyl acetate, and 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, ethylene glycol. To do.

The easy-adhesion layer is formed by applying the varnish on the cycloolefin resin film 1. The method of applying the varnish can be appropriately selected depending on the situation of the varnish and the coating process, and examples thereof include a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method, and a die coating method. Can be applied by a coating method or an extrusion coating method.

The easy adhesion layer can be formed by curing the coating film after applying the varnish. As the 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/using an ultraviolet irradiator. in the irradiation intensity of cm ^2, the amount of work steps and the like that are cured with ultraviolet processing 50~400mJ / cm ^2. An ultraviolet lamp is generally used as an ultraviolet ray source, and specifically, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a metal halide lamp and the like can be mentioned. It may be in an inert gas such as nitrogen or argon.

It is preferable to perform heating during the ultraviolet curing treatment. The ultraviolet light irradiation advances the curing reaction of the adhesive resin composition and simultaneously forms a crosslinked structure. By heating at this time, the formation of the crosslinked structure can be sufficiently promoted even with a low ultraviolet ray amount. The heating temperature can be set according to the degree of crosslinking, 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, or the like can be appropriately adopted.

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 further preferably 0.8 μm to 1.2 μm. .. By setting the thickness of the easy-adhesion layer within the above range, the adhesion of the conductive layer and the flexibility of the film can be improved.

(Hard coat layer)
A hard coat layer may be provided as the underlayer. Further, particles may be added to the hard coat layer in order to prevent blocking between the conductive films and enable production by the roll-to-roll method.

For forming the hard coat layer, the same adhesive composition as that for the easy adhesion layer can be preferably used. In order to impart anti-blocking property, it is preferable to add particles to the adhesive composition. As a result, irregularities can be formed on the surface of the hard coat layer, and the anti-blocking property can be suitably imparted to the conductive film 100.

As the above-mentioned particles, those having transparency such as various metal oxides, glass and plastics can be used without particular limitation. For example, silica, alumina, titania, zirconia, inorganic particles such as calcium oxide, polymethylmethacrylate, polystyrene, polyurethane, acrylic resin, acrylic-styrene copolymer, benzoguanamine, melamine, crosslinked or not composed of various polymers such as polycarbonate. Examples include crosslinked organic particles and silicone particles. One kind or two or more kinds of particles can be appropriately selected and used.

The average particle size and blending amount of the above particles can be appropriately set while considering the degree of surface irregularities. The average particle diameter 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 resin solid content of the composition.

(Dielectric layer)
As the underlayer, one or more dielectric layers may be provided. The dielectric layer is formed of an inorganic material, an organic material, or a mixture of an inorganic material and an organic material. Materials for forming the dielectric layer include NaF, Na ₃ AlF ₆ , LiF, MgF ₂ , CaF ₂ , SiO ₂ , LaF ₃ , CeF ₃ , Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , ZrO ₂ , Examples thereof include inorganic substances such as ZnO, ZnS, and SiO _x (x is 1.5 or more and less than 2), and organic substances such as acrylic resin, urethane resin, melamine resin, alkyd resin, and siloxane polymer. In particular, it is preferable to use a thermosetting resin made of a mixture of a melamine resin, an alkyd resin, and an organic silane condensate as the organic material. The dielectric layer can be formed using the above materials by a coating method such as a gravure coating method or a bar coating method, a vacuum vapor deposition method, a sputtering method, an ion plating method, or the like.

The thickness of the dielectric layer is preferably 10 nm to 250 nm, more preferably 20 nm to 200 nm, and further preferably 20 nm to 170 nm. If the thickness of the dielectric layer is too small, it is difficult to form a continuous film. If the thickness of the dielectric layer is excessively large, cracks are likely to occur in the dielectric layer.

The dielectric layer may have nanoparticles having an average particle size of 1 nm to 500 nm. The content of nanoparticles in the dielectric layer is preferably 0.1% by weight to 90% by weight. The average particle size of the nanoparticles used in the dielectric layer is preferably in the range of 1 nm to 500 nm, and more preferably 5 nm to 300 nm, as described above. Further, the content of nanoparticles in the dielectric layer is more preferably 10% by weight to 80% by weight, and further preferably 20% by weight to 70% by weight.

Examples of the inorganic oxide forming the nanoparticles include particles of silicon oxide (silica), hollow nanosilica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, zirconium oxide, niobium oxide and the like. Among these, fine particles of silicon oxide (silica), titanium oxide, aluminum oxide, zinc oxide, tin oxide, zirconium oxide, and niobium oxide are preferable. These may be used alone or in combination of two or more.

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 thereof is not exceeded.

<Examples 1 and 2: Preparation of double-sided conductive film with single-sided protective film>
First, a long resin film made of a polyethylene terephthalate film having a width of 1.100 m, a length of 2500 m and a thickness shown in Table 1 (manufactured by Toray Film Co., Ltd., product name “150-TT00A”, hereinafter referred to as PET film). Was wound around a delivery roll and placed in a sputtering apparatus as shown in FIG. After that, the inside of the sputtering apparatus was evacuated to a high vacuum of 3.0×10 ⁻³ Torr, and in that state, the long-sized resin film was sent out from the roll to the take-up roll to perform sputter film formation. In the atmosphere of 3.0×10 ⁻³ Torr consisting of 100% by volume of Ar gas, Cu was used as the metal target material, and the first conductive layer was sputter-deposited on one surface by the sintered body DC magnetron sputtering method. Then, by winding the film on a delivery roll, a wound body of a single-sided conductive film having a conductive layer formed on one surface was produced. Table 1 shows the line transport speed during sputter film formation, the number N of repetitions of sputter film formation, the number T of targets per line, and the power density P [kW/m ² ] per target. In addition, the total power density during sputtering film formation was calculated based on the following formula.
Total power density=N×T×P
(N is the number of times sputtering film formation is repeated, T is the number of targets per line, and P is the power density [kW/m ² ] per target.)

The adhesive layer surface side of the protective film (“FSA020M” manufactured by Futamura Chemical Co., Ltd.) having the thickness shown in Table 1 is attached to the first conductive layer surface side of the wound body of the prepared single-sided conductive film to protect one side. A wound body of a single-sided conductive film with a single-sided protective film, in which films were stuck together, was produced.

By forming a second conductive layer on the opposite side of the surface of the wound body of the prepared single-sided conductive film with a single-sided protective film from the side on which the protective film is provided, a second conductive layer is formed by sputtering under the same conditions as the first conductive layer. A double-sided conductive film with a single-sided protective film, which was formed and provided with a protective film on one surface, was produced. Note that both the first conductive layer and the second conductive layer were formed to have the thickness shown in Table 1. Further, the tension applied in the MD direction of the resin film in Example 1 was 290 N, and the tensile stress calculated from the film width and thickness was 1.76 MPa.

<Comparative Examples 1 to 4: Preparation of double-sided conductive film (without protective film)>
A wound body of a single-sided conductive film was produced in the same manner as in Example 1. Next, a double-sided conductive film in which a second conductive layer is sputter-deposited on the side opposite to the first conductive layer of the wound body of the single-sided conductive film under the same conditions as the first conductive layer, and conductive layers are formed on both sides Was produced. Note that both the first conductive layer and the second conductive layer were formed to have the thickness shown in Table 1. Further, the line transport speed during sputtering film formation, the number of times N of sputtering film formation repetition, the number of targets T per line T, and the power density P [kW/m ² ] per target were set to the values shown in Table 1.

<Reference Example 1: Preparation of double-sided conductive film (without protective film)>
A wound body of a single-sided conductive film was produced in the same manner as in Example 1. Next, a double-sided conductive film in which a second conductive layer is sputter-deposited on the side opposite to the first conductive layer of the wound body of the single-sided conductive film under the same conditions as the first conductive layer, and the conductive layers are formed on both sides. Was produced. Note that both the first conductive layer and the second conductive layer were formed to have the thickness shown in Table 1. Further, the line transport speed during sputtering film formation, the number of times N of sputtering film formation repetition, the number of targets T per line T, and the power density P [kW/m ² ] per target were set to the values shown in Table 1.

<Evaluation>
The following evaluation was performed about the produced conductive film. The respective results are shown in Table 1.

(1) Measurement of Thickness The thickness of the conductive layer was measured by observing the cross section of the conductive film with a protective film using a transmission electron microscope (Hitachi, product name “H-7650”).

(2) Evaluation of wrinkles The produced conductive film with a protective film was evaluated for the occurrence of wrinkles. About 10 m was pulled out from the wound body of the conductive film, the conductive film was irradiated with a fluorescent lamp, and the presence or absence of wrinkles in the second conductive layer was visually observed. The case where no wrinkles were observed was evaluated as “◯”, and the case where wrinkles were observed was evaluated as “x”.

(result)
From Table 1, it can be seen that the occurrence of wrinkles was suppressed in the example in which the second conductive layer was formed with the protective film attached to the first conductive layer. On the other hand, it can be seen that wrinkles were generated in Comparative Examples 1 to 4 in which the second conductive layer was formed without the protective film. In addition, wrinkles did not occur in Reference Example 1 in which the conductive layer having a small thickness was formed. From this, it is understood that the occurrence of wrinkles is a phenomenon characteristically seen when forming a thick conductive layer.

1 Resin Film 21 1st Conductive Layer 22 2nd Conductive Layer 31 1st Protective Film 32 2nd Protective Film 100 Conductive Film 300 Film Forming Device 301 Feeding Roll 302 Winding Roll 303, 304 Conveying Roll 310 Film Forming Roll 320 Target

Claims (6)

Step A of forming a first conductive layer on one surface of the resin film,
Step B of attaching a protective film on the first conductive layer, and Step C of forming a second conductive layer having a thickness of 80 nm or more and 300 nm or less on the other surface of the resin film by a sputtering method while feeding the resin film.
A method for producing a conductive film containing: The method for producing a conductive film according to claim 1, wherein in the step A, the first conductive layer is formed by a sputtering method. The method for producing a conductive film according to claim 1, wherein the first conductive layer has a thickness of 80 nm or more and 300 nm or less. The method for producing a conductive film according to claim 1, wherein the protective film has a thickness of 20 μm or more and 200 μm or less. In the said process C, the total power density represented by the following formula in the said sputtering method is 1500 kW/m< ² > or less, The manufacturing method of the electroconductive film of any one of Claims 1-4.
Total power density=N×T×P
(In the formula, N is the number of process repetitions, T is the number of targets per process, and P is the power density [kW/m ² ] per target.) In the said process C, the tensile stress in the MD direction of the said resin film is 1 MPa or more, The manufacturing method of the electroconductive film of any one of Claims 1-5.

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