JP2022181895A - Conductive sheet and method for producing the same - Google Patents

Abstract

To provide a conductive sheet having excellent information extraction prevention properties and a method for producing the same.SOLUTION: A conductive film comprises a substrate, a particle layer comprising bound particles containing transition metal deposited on the substrate, and a protective layer deposited on the substrate so as to cover the particle layer. The protective layer partially comprises an infiltrating portion that infiltrates into the cavities of the particle layer.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a conductive sheet and a manufacturing method thereof.

A conductive sheet is used in various electronic devices and is industrially useful. For example, in automobiles, it is installed on the windshield or the like as an antenna for receiving various radio waves such as TV radio waves and FM radio waves, and radio waves related to positional coordinate information from GPS (global positioning system) satellites used in car navigation systems. film antennas are known.

Film antennas are also widely used in many industries, including transportation, transportation, manufacturing, waste management, mail tracking, baggage reconciliation on aircraft, and toll road toll control (RFID). ) is also used in technology. RFID tags and labels are useful for tracking shipments from the source to the customer and through the customer's supply chain.

As such a film antenna, techniques have been proposed to improve the invisibility of the conductive pattern by forming the antenna with a conductive pattern (see, for example, Patent Documents 1 to 3).

Furthermore, radio frequency identification (RFID) technology is used to track the delivery of goods, as well as to provide services based on the usage of the goods by the end customer (user) after the goods reach the end customer (user). For example, by estimating the usage amount of consumer goods using RFID tags, purchase notifications are periodically sent to users, and by placing RFID tags on packaging containers so that they break when opened, it is possible to check whether or not they have been opened. It can be used for confirmation.

JP 2011-66610 A JP 2011-91788 A JP 2016-105624 A

As described above, RFID tags are used not only for distribution management of goods, but also for improving user experience.

Here, the semiconductor element provided with the RFID tag stores predetermined information according to the intended use of the RFID tag and the environment in which the RFID tag is used. Such information may include information whose leakage should be prevented, for example, information conforming to personal information such that the living environment of the user may be estimated. Therefore, a function is desired to prevent information from being extracted from the RFID tag after use.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a conductive sheet excellent in preventing information extraction and a method for producing the same.

The present inventors have made extensive studies to solve the above problems. As a result, the present inventors have found that a conductive sheet that can solve the above problems can be obtained by manufacturing a conductive sheet by a predetermined manufacturing method, and have completed the present invention.

[1]
a substrate;
a particle layer in which transition metal-containing particles are bonded and laminated on the substrate;
a protective layer laminated on the substrate so as to cover the particle layer;
A part of the protective layer has an infiltration part A that intrudes into the space between the particle layer and the base material,
conductive film.
[2]
The particle layer has voids, and a portion of the protective layer has an infiltration portion B penetrating into the voids.
The conductive film according to [1].
[3]
wherein the protective layer contains an organic substance;
The conductive film according to [1] or [2].
[4]
wherein the protective layer comprises a polymer;
The conductive film according to [3].
[5]
wherein the protective layer comprises polyisoprene;
The conductive film according to [3] or [4].
[6]
wherein the protective layer comprises a silicon compound;
[1] The conductive film according to any one of [5].
[7]
The adhesive strength of the protective layer to the substrate is 0.5 to 5.0 N/cm,
[1] The conductive film according to any one of [6].
[8]
The protective layer has a thickness of 1 μm or more and 1 cm or less.
[1] The conductive film according to any one of [7].
[9]
The penetration portion A has a depth of 5.0 nm or more and 500 nm or less.
[1] The conductive film according to any one of [8].
[10]
The penetration portion B has a depth of 5.0 nm or more and 500 nm or less.
[1] The conductive film according to any one of [9].
[11]
The contact ratio between the substrate and the particle layer is 0% or more and 20% or less,
[1] The conductive film according to any one of [10].
[12]
The average atomic concentration of oxygen in the particle layer is 10% or less,
[1] The conductive film according to any one of [11].
[13]
the particle layer forms a continuous pattern with openings;
[1] The conductive film according to any one of [12].
[14]
wherein the pattern is a pattern composed of a plurality of intersecting fine lines;
The conductive film according to [13].
[15]
The line width of the fine line is 100 nm or more and 1000 μm or less,
The conductive film according to [14].
[16]
The fine wires have a pitch of 1.0 μm or more and 1000 μm or less.
[14] or the conductive film according to [15].
[17]
The film thickness of the particle layer is 30 nm or more and 1000 μm or less,
[1] The conductive film according to any one of [16].
[18]
the substrate has a plurality of layers,
[1] The conductive film according to any one of [17].
[19]
The substrate has a surface layer containing a silicon compound,
[1] The conductive film according to any one of [18].
[20]
The base material is plastic,
[1] The conductive film according to any one of [19].
[21]
The plastic is polyethylene terephthalate,
The conductive film according to [20].
[22]
wherein the transition metal comprises a metal of Group 11 elements of the IUPAC Periodic Table;
[1] The conductive film according to any one of [21].
[23]
wherein the transition metal comprises copper;
[22] The conductive film as described in [22].
[24]
The average particle diameter of the particles constituting the particle layer is 1.0 nm or more and 500 nm or less.
[1] The conductive film according to any one of [23].
[25]
Visible light transmittance is 70% or more and 99% or less,
[1] The conductive film according to any one of [24].
[26]
Sheet resistance is 0.001 Ωcm ^-2 or more and 20 Ωcm ^-2 or less,
[1] The conductive film according to any one of [25].
[27]
Equipped with the conductive film according to any one of [1] to [26],
touch panel.
[28]
Equipped with the conductive film according to any one of [1] to [26],
display.
[29]
Equipped with the conductive film according to any one of [1] to [26],
heater.
[30]
Equipped with the conductive film according to any one of [1] to [26],
electromagnetic shield.
[31]
Equipped with the conductive film according to any one of [1] to [26],
antenna.
[32]
A film forming step of forming a precursor thin film on a substrate;
A plasma treatment step of reacting the precursor thin film with plasma for 180 seconds or more and 2000 seconds or less in the presence of a gas composed of molecules containing both hydrogen atoms and oxygen atoms at a partial pressure of 10 Pa to 1000 Pa to form a particle layer. When,
a lamination step of laminating a protective layer on the base material so as to cover the particle layer;
A method for producing a conductive film.
[33]
the molecule containing both a hydrogen atom and an oxygen atom is a water molecule;
[32] The method for producing the conductive sheet described in [32].
[34]
wherein the precursor thin film forms a continuous pattern with openings;
[32] or [33] The method for producing a conductive sheet.
[35]
The opening ratio of the precursor thin film to the substrate is 20% or more and 99% or less,
[32] The method for producing a conductive sheet according to any one of [34].
[36]
Using microwave plasma in the plasma treatment step,
[32] The method for producing a conductive film according to any one of [35].

ADVANTAGE OF THE INVENTION According to this invention, the electroconductive sheet which is excellent in information extraction prevention property, and its manufacturing method can be provided.

It is a schematic sectional drawing which shows an example of the electroconductive sheet of this embodiment. FIG. 2 is an enlarged view of a cross section S1 in FIG. 1; It is a schematic top view which shows an example of the electroconductive sheet of this embodiment. 1 is a perspective view showing one mode of an RF tag having the conductive sheet of the present embodiment as a transparent antenna; FIG. 1 is a cross-sectional photograph of a conductive sheet of Example 1. FIG.

Hereinafter, embodiments of the present invention (hereinafter referred to as "present embodiments") will be described in detail with reference to the drawings as necessary, but the present invention is not limited thereto and the gist thereof. Various modifications are possible without departing from the above. In the drawings, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted. Moreover, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to the illustrated ratios.

1. Conductive Sheet The conductive sheet of the present embodiment comprises a base material, a particle layer laminated on the base material and containing particles containing a transition metal bonded thereto, and laminated on the base material so as to cover the particle layer. and a protective layer, a portion of the protective layer having an intrusion portion A penetrating into the space between the particle layer and the substrate. By having this penetration part A, it is excellent in information extraction prevention property.

FIG. 1 shows a schematic cross-sectional view showing an example of the conductive sheet of the present embodiment, and FIG. 2 shows an enlarged view of a cross section S in FIG. FIG. 1 shows a schematic cross-sectional view of a conductive sheet 100 in which a particle layer 10 is arranged on a substrate 20. As shown in FIG. The particle layer 10 shown in FIG. 1 is expressed as a particle layer formed by bonding transition metal particles, and the cross section thereof may have pores 11 .

As shown in FIG. 2, the conductive sheet 100 of the present embodiment has a protective layer 30 laminated on the base material 20 so as to cover the particle layer 10, and a part of the protective layer 30 is the particle layer and the base material. It has an intrusion portion A 31a intruding into the space with the material and, if necessary, an intrusion portion B 31b intruding into the voids (hollows) on the surface of the particle layer 10 . That is, the protective layer 30 is formed so as to follow the surface shape of the particle layer 10 . As a result, the interface between the protective layer 30 and the particle layer 10 has a larger contact area than the interface between the substrate 20 having a smooth surface and the particle layer 10. 30 becomes a structure that wraps the particle layer 10 .

Therefore, when the protective layer 30 is peeled off from the base material 20 of the conductive sheet 100 of the present embodiment, the particle layer 10 tends to adhere to the protective layer 30 side rather than the base material 20. is disconnected. When the particle layer 10 is, for example, an RFID transparent antenna, the antenna portion (the particle layer 10) is physically destroyed by peeling off, making it impossible to access the RFID semiconductor element, thereby preventing the information from being stolen. demonstrated. The configuration of the conductive sheet 100 will be described in detail below.

1.1. Particle Layer The particle layer 10 is formed by bonding particles containing a transition metal. Note that the particle layer 10 may have the pores 11 at the interface with the substrate 20 or may have the pores 11 at locations other than the interface with the substrate 20 .

In the present embodiment, the contact ratio between the substrate 20 and the particle layer 10 may be used from the viewpoint of expressing the degree of the pores 11 existing at the interface with the substrate 20 . The contact ratio between the substrate 20 and the particle layer 10 is preferably 0-20%, more preferably 0-10%, and even more preferably 0-5%. When the contact rate is within the above range, there is a tendency for the information extraction prevention functionality to be further improved. A contact ratio of 0% means that the penetration portion A is formed between the base material 20 and the particle layer 10 and the base material 20 and the particle layer 10 are not in direct contact with each other.

A method for adjusting the contact ratio is not particularly limited, but includes, for example, a method of subjecting the precursor thin film to plasma treatment under specific conditions by a manufacturing method described later. During the plasma treatment under these specific conditions, the transition metal sintered particles preferentially grow on the surface side of the precursor thin film, and along with this, pores increase on the interface side between the substrate 20 and the particle layer 10. transformation progresses. As a result, the pores 11 are likely to be formed at the interface between the base material 20 and the particle layer 10, and the above contact ratio can be achieved. However, the method of adjusting the contact ratio is not limited to the above.

The average particle diameter of the particles constituting the particle layer 10 is preferably 1.0 to 500 nm, more preferably 5.0 to 400 nm, and even more preferably 10 to 300 nm. , the sheet resistance tends to be further lowered. The average particle size of the particles forming the particle layer 10 can be measured by a transmission electron image of the cross section of the particle layer 10 .

1.1.1. Composition The particle layer 10 of the present embodiment contains a transition metal and, if necessary, may contain other atoms such as oxygen atoms, carbon atoms, and phosphorus atoms. Moreover, the transition metal may exist in the state of a metal compound such as an oxide in addition to the state of an elemental metal.

In the particle layer 10, the transition metal may exist in the state of a metal compound such as an oxide in addition to the state of a metal element. The transition metal atoms contained in the particle layer 10 are not particularly limited as long as they are metals of Group 3 to Group 11 elements in the IUPAC periodic table, but preferably contain metals of Group 11 elements. It more preferably contains copper, even more preferably copper. By using such a transition metal, the conductivity of the particle layer 10 tends to be further improved.

The types of metal compounds containing transition metals are not particularly limited, but examples include sulfides, selenides, tellurides, nitrides, phosphides, and oxides. Among these, oxides are preferred because they are less harmful to the human body and relatively easy to produce.

In addition to the above contact ratio, the atomic concentration of oxygen in the particle layer may be defined from the viewpoint of expressing the degree of voids 11 existing at the interface with the substrate 20 . This is because the oxygen concentration in the particle layer tends to decrease due to reduction as particle growth and pore growth progress during plasma processing. The average atomic concentration of oxygen in the particle layer is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less. When the atomic concentration of oxygen in the particle layer is within the above range, the information extraction prevention functionality tends to be further improved.

The concentration of each atom contained in the particle layer is analyzed by elemental analysis (STEM-EDX analysis) by energy dispersive X-ray analysis (EDX) attached to a scanning transmission electron microscope (STEM) of the cross section of the conductive sheet. can be obtained by doing In this embodiment, the concentration of each atom is indicated by element concentration (atom %) unless otherwise specified.

In the STEM-EDX analysis, the cross section of the conductive sheet is measured. For example, when the conductive sheet is a fine metal wire pattern described later, the measurement sample includes the cross section of the fine metal wire perpendicular to the extending direction of the fine metal wire. Thin slices are preferred. In preparing the measurement sample, if necessary, the conductive sheet may be embedded in a support such as an epoxy resin, and then a thin section may be formed.

The method for forming the thin piece is not particularly limited as long as it is a method that can suppress damage to the metal fine wire cross section due to the formation and processing of the cross section, but a processing method using an ion beam (for example, BIB (Broad Ion Beam) processing is preferable. method, FIB (Focused Ion Beam) processing method), precision mechanical polishing, an ultramicrotome, and the like can be used.

Next, the cross section of the formed metal fine wire is observed by STEM to obtain an STEM image of the cross section of the metal fine wire. At the same time, STEM-EDX analysis can be performed by measuring the elemental mapping of the cross section of the metal wire by EDX. From the viewpoint of preventing oxidation and contamination of the cross section of the metal fine wire, it is preferable to perform the formation of the cross section of the metal fine wire and the STEM-EDX analysis in an inert atmosphere such as argon or in a vacuum.

1.1.2. Film thickness The film thickness of the particle layer 10 is preferably 30 nm to 1000 μm, more preferably 50 nm to 100 μm, even more preferably 100 nm to 10 μm, still more preferably 200 to 1000 nm, still more preferably 300-500 nm. When the film thickness is 30 nm or more, the sheet resistance of the particle layer 10 tends to further decrease. In addition, since the irregularities on the surface of the particle layer 10 become deeper as the film thickness increases, the intrusion portion B31b can also penetrate deeper, and the information extraction prevention functionality tends to be further improved. Further, when the film thickness is 1000 μm or less, transparency tends to be further improved when the particle layer 10 is formed as a pattern having openings, which will be described later. Further, when the film thickness is 1000 μm or less, the pattern of the particle layer 10 tends to be formed more easily.

The film thickness of the particle layer 10 can be determined by cross-sectional STEM evaluation of the conductive sheet 100 . More specifically, the average value of the film thicknesses measured at arbitrary three cross sections can be taken as the film thickness of the particle layer 10 . Note that the particle layer 10 of the present embodiment may be a thin film having a uniform thickness, or a thin film having unevenness on the surface or having a thin portion depending on the position of the particle layer 10. good.

Regardless of whether the interface between the substrate 20 and the particle layer 10 has a relatively large number of pores 11, the film thickness of the particle layer 10 in the present embodiment is the distance from the surface of the substrate 20 to the surface of the particle layer 10. distance.

1.1.3. Pattern The particle layer 10 may have a continuous pattern with openings or a solid pattern without openings. The pattern of the particle layer 10 can be designed according to the intended use of the electronic device, and may be a regular pattern or an irregular pattern. Here, the opening means a portion where the conductive sheet does not exist, and light can pass through the opening portion. A continuous pattern means that connection (contact) is confirmed by an optical microscope, and such a pattern can be electrically connected.

Among these, the particle layer 10 preferably has a continuous pattern with openings. By providing openings in this manner, a light-transmissive conductive sheet can be obtained. In addition, forming the particle layer 10 in a continuous pattern with openings facilitates the formation of the intrusion portion A, and as a result, it is preferable in that a conductive sheet with excellent information confidentiality can be produced. This is because in the plasma treatment process described later, the patterned precursor thin film having openings makes it easier to adjust the progress of the plasma reaction compared to the solid film having a relatively large contact area with the substrate. This is because it is possible to adjust the adhesion between the particle layer and the substrate within a predetermined range, thereby facilitating the formation of the penetrating portion A. Here, the mechanism by which the continuous pattern with openings facilitates the formation of the encroaching portion A is not bound by any particular theory, but is presumed as follows. That is, in the plasma treatment step, the increase in pores between the particle layer and the substrate progresses faster than in the solid film, and relatively large pores are formed inside the particle layer. This is because the contact rate between the base material and the particle layer is lowered because the temperature at the interface of the thin film increases due to the heat of plasma reaction compared to when there is no opening, which contributes to the formation of the infiltration portion A.

When the particle layer 10 has a continuous pattern with openings, the opening ratio of the openings is preferably 20 to 99%, more preferably 30 to 97%, still more preferably 50 to 95%. As the aperture ratio increases, the information extraction prevention functionality of the particle layer 10 tends to be further improved. Also, the sheet resistance of the particle layer 10 tends to decrease as the aperture ratio decreases.

The appropriate aperture ratio of the pattern of the particle layer 10 varies depending on the shape of the pattern of the particle layer 10 as well. Further, the aperture ratio of the pattern of the particle layer 10 can appropriately combine the upper limit and the lower limit according to the required performance (transmittance and sheet resistance) of the target electronic device.

The "aperture ratio of the pattern of the particle layer 10" can be calculated by the following formula for the area where the pattern of the particle layer 10 is formed on the substrate. The area where the pattern of the particle layer 10 is formed on the substrate excludes the edge portion where the pattern of the particle layer 10 is not formed.
Aperture ratio of pattern of particle layer 10 = (1-area occupied by pattern of particle layer 10/area of substrate) x 100

When the particle layer 10 has a continuous pattern with openings, the diameter of the openings is preferably 0.5-1000 μm, more preferably 1-500 μm, and even more preferably 10-300 μm. When the size of the opening is within the above range, there is a tendency for the information extraction prevention functionality to be further improved.

Moreover, the continuous pattern having openings is not particularly limited, but for example, a pattern formed by crossing a plurality of fine lines is preferable. In this case, the fine lines correspond to the conductive sheet, and the gaps between the fine lines are the openings.

A specific aspect of the pattern formed by a plurality of fine lines will be described below, but the pattern in this embodiment is not limited to the following. In the following description, the fine metal wire means the particle layer 10 having a fine wire shape in plan view, and the fine metal wire pattern means a pattern formed by a plurality of fine metal wires.

FIG. 3 shows a schematic top view showing an example of the pattern 40 of the conductive sheet 100 of this embodiment. FIG. 3 is a top view of the conductive sheet 100 in which the particle layer 10 is arranged on the substrate 20, viewed from the side where the particle layer 10 is formed. In FIG. 3, the particle layer 10 is in the form of fine lines, and the fine lines are shown as intersecting in a grid. Here, the fine wire-like particle layer 10 is referred to as a fine metal wire 10'. The cross section of FIG. 1 described above is a cross section of the thin metal wire 10' taken along the line A-A'.

As shown in FIG. 3, the continuous pattern means that, for example, a plurality of fine metal wires 10′ intersect each other to form a continuous layer, so that current can be supplied at any two points on the particle layer 10 extending in the plane direction. It is configured as follows. Having openings means, for example, having discontinuous openings 50 between a plurality of thin metal wires 10'. In the present embodiment, a conductive continuous layer formed by the fine metal wires 10 ′ and openings is referred to as a fine metal wire pattern 40 .

Here, the line width W of the fine metal wires 10′ constituting the fine metal wire pattern 40 is defined by projecting the fine metal wires 10′ onto the surface of the substrate 20 from the side of the substrate 20 on which the fine metal wire pattern 40 is arranged. It means the line width of the thin metal wire 10' when The "line width when projected" is defined as the line width when, for example, the interface of the particle layer 10 in contact with the base material is the thickest as shown in FIG. Also, the pitch P is defined as the sum of the line width W and the distance L between the thin metal lines.

Specific examples of the fine metal wire pattern include a mesh pattern formed by intersecting a plurality of fine metal wires in a mesh pattern, and a line pattern formed by forming a plurality of substantially parallel fine metal wires. Also, the fine metal line pattern may be a combination of a mesh pattern and a line pattern. The meshes of the mesh pattern may be squares, rectangles, or polygons such as rhombuses. Further, the thin metal wires forming the line pattern may be straight lines or curved lines. Further, the thin metal wires forming the mesh pattern can also be curved.

1.1.4. Line Width The line width W is preferably 100 nm to 1000 μm, more preferably 200 nm to 500 μm, still more preferably 300 nm to 100 μm, even more preferably 400 nm to 50 μm, still more preferably 500 nm to 5 .0 μm.

When the line width W of the metal fine wire is 100 nm or more, the conductivity of the metal fine wire can be sufficiently ensured, and the sheet resistance tends to be further reduced. In addition, it is possible to sufficiently suppress the decrease in electrical conductivity due to oxidation, corrosion, etc. of the surface of the fine metal wire. Furthermore, when the aperture ratio is the same, the thinner the line width of the metal fine wires, the more the number of the metal fine wires can be increased. As a result, the electric field distribution of the conductive sheet becomes more uniform, making it possible to manufacture electronic devices with higher resolution. Also, even if some of the fine metal wires are broken, the other fine metal wires can compensate for the effects of this breakage.

On the other hand, when the line width W of the fine metal wire is 5.0 μm or less, the visibility of the fine metal wire tends to be further lowered, and the transparency of the conductive sheet and the conductive sheet including the same tends to be further improved.

1.1.5. Aspect Ratio The aspect ratio represented by the thickness T of the fine metal wire to the width W of the fine metal wire is preferably 0.05 to 1.00, more preferably 0.08 to 0.90, and still more preferably is between 0.10 and 0.80. When the line width W is constant, the larger the aspect ratio, the more the conductivity tends to improve without lowering the transmittance. In addition, when the aspect ratio is 1.00 or less, there is a tendency to suppress decrease in transmittance due to excessive film thickness.

1.1.6. Pitch Pitch P is preferably 1.0 to 1000 μm, more preferably 5.0 to 500 μm, even more preferably 50 to 250 μm, still more preferably 100 to 250 μm. When the pitch P is 1.0 μm or more, the transparency of the conductive sheet and the conductive sheet including the same tends to be further improved. Further, when the pitch P is 1000 μm or less, the conductivity tends to be further improved. When the shape of the fine metal line pattern is a mesh pattern, an aperture ratio of 99% can be obtained by setting the pitch of the fine metal line pattern having a line width of 1 μm to 200 μm.

The line width W, aspect ratio, and pitch P of the fine metal line pattern can be confirmed by observing the cross section of the conductive sheet with an electron microscope or the like. Also, the line width and pitch of the metal fine line pattern can be observed with a laser microscope or an optical microscope. Also, since the pitch P and the aperture ratio have a relational expression to be described later, if one is known, the other can be calculated. In addition, methods for adjusting the line width W, aspect ratio, and pitch P of the metal fine line pattern to desired ranges include a method for adjusting the grooves of a plate used in the method for manufacturing a conductive sheet described later, and a method for adjusting the grooves of the metal particles in the ink. and a method of adjusting the average particle size of the.

The sheet resistance of the conductive sheet tends to be lowered by increasing the aspect ratio (height) of the fine metal wires. Moreover, it can be adjusted by selecting the kind of metal material that constitutes the thin metal wire.

1.1.7. Visible Light Transmittance The conductive sheet preferably has a visible light transmittance of 70 to 99%, more preferably 75 to 95%, still more preferably 80 to 90%. Here, the visible light transmittance can be measured by calculating the average transmittance in the range of visible light (360 to 830 nm) in accordance with the total light transmittance of JIS K 7361-1:1997. . The visible light transmittance of a patterned thin film tends to be improved by reducing the line width of the fine metal line pattern or by improving the aperture ratio.

1.1.8. Sheet resistance The sheet resistance of the conductive sheet is preferably 0.001 to 20 Ωcm ^-2 , more preferably 0.01 to 17.5 Ωcm ^-2 , still more preferably 0.01 to 15 Ωcm ^-2 , Even more preferably, it is 0.1 to 10 Ωcm ^-2 . The lower the sheet resistance, the more the electrical conductivity tends to improve.

1.1.9. Haze The haze of the conductive sheet is preferably 0.01 to 5.00%, more preferably 0.01 to 3.00%, still more preferably 0.01 to 1.00%. A haze of 5.00% or less tends to further suppress fogging of the conductive sheet against visible light. Haze in this specification can be measured according to JIS K 7136:2000 haze.

1.2. Substrate The substrate can be appropriately selected according to the application of the conductive sheet, and is not particularly limited. Examples include transparent inorganic substrates such as glass, opaque inorganic substrates such as metal plates, and plastic films. Examples include transparent or opaque organic substrates. Among these, plastic is preferable from the viewpoint of obtaining a flexible and transparent conductive sheet. Moreover, these substrates may have any layer on the surface, or may be subjected to any surface treatment such as corona treatment.

As for the form of the base material, a plate-like one or a film-like one can be used, and a film-like one is preferable from the viewpoint of excellent freedom of form.

Examples of plastics include, but are not limited to, acrylate, methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, nylon, and aromatic polyamide. , polyetheretherketone, polysulfone, polyethersulfone, polyimide, and polyetherimide.

Among these, it is preferable to use polyethylene terephthalate (PET) from the viewpoint of high productivity including the cost reduction effect for manufacturing the conductive sheet. Moreover, it is preferable to use a polyimide from a viewpoint of being excellent in the heat resistance of a conductive sheet. Furthermore, it is preferable to use polyethylene terephthalate and/or polyethylene naphthalate from the viewpoint of being advantageous for adhesion between the thin film and the substrate.

The base material of the thin film used in the present embodiment may be made of one kind of material, or may be made of a laminate of two or more kinds of materials. Further, when the transparent substrate is a multilayer body in which two or more kinds of materials are laminated, the transparent substrate may be a laminate of organic substrates or inorganic substrates. The base material may be laminated.

The thickness of the substrate is preferably 5.0 to 500 μm, more preferably 5.0 to 300 μm, and still more preferably 10 to 100 μm, from the viewpoint of excellent morphological freedom and/or excellent transparency. is.

As shown in FIG. 1, the substrate 20 can be taller than the openings 40 of the particle layer 20 along which the particle layer 10 is disposed. That is, the substrate 20 can have raised portions 21 along the particle layer 10 disposed thereon. By doing this, when the protective layer 30 is laminated, the protective layer 30 can be supported by the protuberance 1 and can be moved up between the particle layer 10 and the base material 20, and the infiltration part A described later. 31a can be favored.

In the present embodiment, the mechanism by which the raised portion 21 is formed on the base material 20 is not particularly limited, but is presumed as follows. That is, the protruding portion 21 is formed at least in a region of the base material 20 where the particle layer 10 containing the transition metal is formed. According to this, the protuberance 21 is formed by the base material 20 in the region (the region corresponding to the opening 50) not covered with the precursor thin film containing the transition metal. In the plasma reaction process, the thickness of the region is reduced by being modified or etched, and as a result, the base material 20 in the region covered with the precursor thin film (the region to become the particle layer 10) is relatively raised. is thought to be formed by

1.2.1. Surface Layer The substrate may have a plurality of layers, and may have a surface layer at the contact portion with the conductive sheet. By laminating the surface layer on the base material, when the metal component in the ink is sintered by a baking means such as plasma, the base material is prevented from being etched in places not covered with the fine metal wire pattern by plasma or the like. be able to.

Components contained in the surface layer are not particularly limited, but examples include silicon compounds (e.g., (poly)silanes, (poly)silazanes, (poly)silthianes, (poly)siloxanes, silicon, silicon carbide, silicon oxide, silicon nitride, silicon chloride, silicate, zeolite, silicide, etc.), aluminum compounds (eg, aluminum oxide, etc.), magnesium compounds (eg, magnesium fluoride), and the like. The above polysilanes, polysilazanes, polysilthianes, and polysiloxanes may have a linear or branched, cyclic, or network configuration. These components may be used individually by 1 type, and may be used in combination of 2 or more type.

Among these, silicon compounds, aluminum oxide, and magnesium fluoride are preferred, and silicon oxide, silicon nitride, aluminum oxide, and magnesium fluoride are more preferred. By using such a component, the durability against plasma tends to be further improved, and the information extraction prevention functionality between the conductive sheet and the substrate tends to be further improved. In addition, by using such a component, the transparency and durability of the conductive sheet tend to be further improved, and the productivity that contributes to the cost reduction effect for manufacturing the conductive sheet tends to be more excellent. be.

The surface layer is formed by vapor deposition methods such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), or by coating and drying a composition in which the components contained in the surface layer are dispersed in a dispersion medium. can do. This composition may contain a dispersant, a surfactant, a binder, etc., if necessary.

When the surface layer is included, silicon may be incorporated into the conductive sheet through a plasma reaction. The silicon atom Si contained in the metal fine wire may exist in the form of a silicon atom or a silicon compound, and a form in which the silicon atom or the silicon compound and the metal atom are bonded (for example, Si—M, Si—O— M etc.).

1.2.2. Thickness The thickness of the surface layer is preferably 0.01 to 500 μm, more preferably 0.05 to 300 μm, still more preferably 0.10 to 200 μm. When the thickness of the surface layer is 0.01 μm or more, there is a tendency for the information extraction prevention functionality to be further improved. Moreover, the thickness of the surface layer is 500 μm or less, so that the flexibility of the substrate can be ensured.

1.2.3. Volume Resistivity The surface layer preferably has an antistatic function to prevent disconnection of the fine metal wire pattern due to static electricity. From the viewpoint of having an antistatic function, the surface layer preferably contains at least one of a conductive inorganic oxide and a conductive organic compound.

From the viewpoint of antistatic function, the surface layer preferably has a volume resistivity of 100 to 100,000 Ωcm, more preferably 1,000 to 10,000 Ωcm, and more preferably 2,000 to 8,000 Ωcm. When the surface layer has a volume resistivity of 100,000 Ωcm or less, the antistatic function tends to be further improved. In addition, when the surface layer has a volume resistivity of 100 Ωcm or more, the electrical conductivity between the fine metal wire patterns is further reduced, and it can be suitably used for touch panels and the like.

The volume resistivity can be adjusted by the content of the conductive inorganic oxide, conductive organic compound, or the like in the surface layer. For example, when silicon oxide with high plasma resistance (volume resistivity of 1014 Ω·cm or more) and an organic silane compound, which is a conductive organic compound, are included in the surface layer, the volume resistivity is reduced by increasing the content of the organic silane compound. be able to. On the other hand, by increasing the content of silicon oxide, although the volume resistivity increases, it has high plasma resistance, so it can be made into a thin film without deteriorating the optical properties.

1.3. Protective Layer The conductive sheet of this embodiment has a protective layer 30 on the particle layer 10 . The protective layer 30 is laminated on the base material 20 so as to cover the particle layer 10, and can be formed so as to enclose the particle layer 10 by the penetration part A 31a described below.

1.3.1. Penetration Part As shown in FIGS. 1 and 2, the protective layer 30 has an penetration part A 31a, a part of which penetrates into the space between the particle layer 10 and the substrate 20, and optionally, A part of the protective layer 30 may have an intrusion portion B 31b intruding into a void (recess) on the surface of the particle layer 10 . These penetrating portions will be described below.

The intrusion portion A 31 a is formed by partly intruding into the space between the particle layer 10 and the substrate 20 when the protective layer 30 is laminated so as to cover the particle layer 10 . In the present embodiment, the mechanism by which the intrusion portion A is formed is not particularly limited, but is presumed as follows. That is, by subjecting the precursor thin film placed on the substrate to a plasma reaction under predetermined conditions, the transition metal-containing particle layer and the substrate come to have specific adhesiveness. Since the particle layer containing the transition metal and the base material have specific adhesion in this way, when the protective layer on which the adhesive layer having a certain fluidity is formed is pressed from above the particle layer, the particle layer A portion of the protective layer can penetrate between the particle layer and the base material, and this penetration expands the space between the particle layer and the base material, thereby forming an infiltrated portion A. It is usually difficult to achieve specific adhesion between the particle layer containing the transition metal and the substrate. It's amazing to have a part that does.

In the present embodiment, the distance between the particle layer 10 and the substrate 20 by the penetration portion A 31a is referred to as the "depth" of the penetration portion A. As shown in FIG. The depth of this penetrating portion A is preferably 5.0 to 500 nm, more preferably 50 to 400 nm, still more preferably 80 to 300 nm. When the depth of the intrusion portion A is 5.0 nm or more, the holding force of the particle layer 10 by the substrate 20 is weakened, and there is a tendency that the information extraction prevention functionality is further improved.

Furthermore, as shown in FIGS. 1 and 2, the intruding part B 31b partially intrudes into the voids (recesses) on the surface of the particle layer 10 when the protective layer 30 is laminated so as to cover the particle layer 10. can be formed by In the present embodiment, the mechanism by which the penetrating portion B is formed is not particularly limited, but is presumed as follows. That is, by subjecting a precursor thin film placed on a substrate to a plasma reaction under predetermined conditions, it is possible to form a specific particle layer. When the protective layer on which the adhesive layer having a certain fluidity is formed is pressed from above the particle layer, part of the protective layer penetrates into the gaps exposed to the protective layer in the particle layer, and the infiltration portion is formed. B is formed.

The depth of the penetrating portion B is preferably 5.0 to 500 nm, more preferably 50 to 400 nm, still more preferably 80 to 300 nm. Since the depth of the penetrating portion B is 5.0 nm or more, the contact area of the interface between the protective layer 30 and the particle layer 10 is increased, and the penetrating portion penetrates into the voids on the surface of the particle layer 10 like an anchor. Since the amount of B 31b increases, the information extraction prevention functionality tends to be further improved.

The depth of the penetration portion B can be obtained by cross-sectional STEM evaluation of the conductive sheet 100 . More specifically, the depth of the penetration portion B can be the average value of the maximum depths of the penetration portion B measured at arbitrary three cross sections. As shown in FIG. 2, the depth of the penetrating portion B is the depth of the penetrating portion B 31b penetrating to the side of the base material 20 with respect to the film thickness of the particle layer 10 defined by the above method. means depth.

The penetrating portion A and the penetrating portion B may each be formed integrally with the protective layer. Also, the intrusion portion A and the intrusion portion B may be in contact with each other.

1.3.2. Configuration The protective layer 30 is not particularly limited, but preferably has transparency and can exhibit good adhesion to the conductive sheet or base material. In addition, the protective layer 30 may have a plurality of layers, for example, an inner layer in contact with the substrate 20 and the particle layer 10 and a surface layer opposite to the inner layer. Protective layer 30 may also be a multi-layer body having more layers.

The material constituting such a protective layer is not particularly limited, but examples thereof include organic substances such as polymers. The polymer is not particularly limited, but examples include phenol resins, thermosetting epoxy resins, thermosetting polyimides, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, polyurethanes, diallyl phthalate resins, silicone resins, and the like. Thermosetting resin; UV curable resin such as urethane acrylate, acrylic resin acrylate, epoxy acrylate, silicone acrylate, UV curable epoxy resin; Thermoplastic resin such as polyolefin, polyester; Commercially available coating agent; Polyisoprene, polyisoprene- Rubber-based adhesives such as butylene; acrylic-based adhesives; silicone-based adhesives and the like can be used.

Among these, the inner layer of the protective layer 30 is preferably an adhesive, more preferably a rubber-based adhesive, and even more preferably a silicon compound such as polyisoprene or silicone. By using an adhesive as the protective layer 30, the protective layer 30 can easily penetrate between the particle layer 10 and the base material 20 and into the voids (hollows) on the surface of the particle layer 10. It becomes easy to form 31b. In addition, since the protective layer 30 adheres to the particle layer 10, when the protective layer 30 is peeled off from the substrate 20, the particle layer 10 tends to adhere to the protective layer 30 side rather than the substrate 20. . Therefore, by using such an adhesive on the surface of the protective layer 30 that comes into contact with the particle layer 10, there is a tendency for the information extraction prevention functionality to be further improved.

Such a protective layer 30 is not particularly limited, but for example, an adhesive tape having an adhesive layer laminated on a substrate such as polyethylene terephthalate may be used.

1.3.3. Adhesion Strength The adhesion strength of the protective layer to the substrate is preferably 0.5 to 5.0 N/cm, more preferably 1.0 to 5.0 N/cm, and still more preferably 2.0 to 5.0 N/cm. 0 N/cm. Since the adhesive strength of the protective layer to the base material is 0.5 N/cm or more, when the protective layer 30 was peeled off from the base material 20, the particle layer 10 adhered to the protective layer 30 side rather than the base material 20. It is easy to become a state, and the information extraction prevention functionality tends to be further improved. In addition, when the adhesive force of the protective layer to the base material is 5.0 N/cm or less, the protective layer 30 can be easily peeled off from the base material 20, and the handleability tends to be further improved. Adhesion can be adjusted by selecting an adhesive as the inner layer of the protective layer 30, for example.

1.3.4. Thickness The thickness of the protective layer is preferably 1.0 μm to 1.0 cm, more preferably 10 μm to 5 mm, and still more preferably 25 to 1000 μm. The thicker the protective layer, the easier it is to peel off the protective layer 30 from the substrate 20, and thus the handleability tends to be further improved. Also, the thinner the thickness of the protective layer is, the more the effect of the protective layer on the transparency of the conductive sheet tends to be suppressed.

The film thickness of the protective layer 30 can be obtained by cross-sectional STEM evaluation of the conductive sheet 100 . More specifically, the average value of the thicknesses of the overlapping portions of the particle layer 10 and the protective layer 30 measured at arbitrary three cross sections is measured, and the thickness of the particle layer 10 is divided from the measured value. can be obtained by

2. Method for producing conductive sheet The method for producing a conductive sheet according to the present embodiment includes a film forming step of forming a precursor thin film on a substrate, and a precursor thin film formed by hydrogen atoms and oxygen atoms at a partial pressure of 10 to 1000 Pa A plasma reaction step of forming a particle layer by reacting with plasma for 180 to 2000 seconds in the presence of a gas containing molecules contained together, and a lamination step of laminating a protective layer on the substrate so as to cover the particle layer. and, if necessary, a surface layer forming step of forming a surface layer on the substrate may be included before the film forming step.

2.1. Surface Layer Forming Step The surface layer forming step is a step of forming the surface layer described above on the substrate. By forming the surface layer, for example, when a plastic substrate is used, the surface layer can prevent denaturation and etching of the plastic due to plasma reaction.

A specific example of the method for forming the surface layer is to form a film of a component forming the surface layer on the surface of the transparent base material using a vapor deposition method such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). A method of forming a surface layer by Another specific example of the surface layer forming step is a method of forming a surface layer by coating the surface of a transparent base material with a composition in which components for forming the surface layer are dispersed in a dispersion medium, and drying the composition. be done. Moreover, the surface layer forming composition may contain a dispersant, a surfactant, a binder, and the like, if necessary.

In the surface layer forming step, it is preferable to use the silicon compound described above as the component forming the surface layer.

2.2. Film Forming Step The film forming step is a step of forming a precursor thin film on the substrate.

2.2.1. Precursor Thin Film The precursor thin film contains a transition metal and is subjected to a plasma reaction process described below to form the particle layer of the present embodiment. As described above, the conductive sheet having the particle layer obtained by subjecting the precursor thin film to plasma treatment under predetermined conditions has excellent information extraction prevention functionality.

Such a precursor thin film can be formed using various methods such as a dry method using a vacuum device or the like and a wet method using ink or the like. Among these methods, the method of forming a precursor thin film by printing an ink on a base material is preferable from the viewpoint of suitability for large-scale production.

The printing method that can be used is not particularly limited, but examples thereof include letterpress printing, gravure printing, bar coat printing, spray coating, spin coating, reverse transfer printing, and the like. Among these, from the viewpoint of being able to print a relatively precise pattern, the formation of the precursor thin film by the plate printing method is preferable.

The plate printing method includes, for example, a step of coating ink on the surface of a transfer medium (hereinafter also referred to as a “blanket”), and contacting the ink-coated blanket surface with the convex surface of the letterpress to form a letterpress. a step of transferring a part of the ink on the blanket surface to the surface of the convex portion of, and contacting the surface of the blanket with the surface of the substrate after a part of the ink has been transferred, and transferring the ink remaining on the blanket surface to the substrate a step of transferring to the surface of the

For example, in such a printing method, various shapes such as the thickness, width, and pitch of the precursor thin film and the concentration of each atom contained in the precursor thin film can be controlled by adjusting the printing conditions and ink.

2.2.2. Ink The ink used in the printing method contains a metal component and a solvent, and may contain a surfactant, a dispersant, a reducing agent, and the like, if necessary.

2.2.2.1. Metal Particles The metal component may be contained in the ink as metal particles or may be contained in the ink as a metal complex. Among these, it is preferable to be contained in the ink as metal particles. The metal particles include metal oxides such as copper oxide, other metal compounds, and core/shell particles in which the core portion is copper and the shell portion is copper oxide, as long as they contain the transition metal atoms described above. It may be an aspect. Among these, metal oxides such as copper oxide are preferable from the viewpoint of handleability.

The average primary particle size of the metal particles is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. Although the lower limit of the average primary particle size of the metal particles is not particularly limited, it may be 1 nm or more. The average primary particle size of the metal particles is preferably 100 nm or less from the viewpoint that the line width W of the fine metal wire to be obtained can be made thinner.

The average secondary particle size of the metal particles is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. From the viewpoint of excellent coatability during thin film formation, it is preferable that each particle is monodisperse and that the average secondary particle diameter is close to the average primary particle diameter.

In the present embodiment, the “average primary particle size” refers to the particle size of each metal particle (so-called primary particle), and an aggregate (so-called secondary particle) formed by gathering a plurality of metal particles. is distinguished from the average secondary particle size, which is the particle size of

2.2.2.2. Surfactant The surfactant is not particularly limited, but examples thereof include fluorine-based surfactants and silicone-based surfactants. The use of such a surfactant tends to improve the coating properties of the ink on the blanket and the smoothness of the coated ink, resulting in a more uniform coating film. In addition, it is preferable that the surfactant is capable of dispersing the metal component and is difficult to remain during firing.

2.2.2.3. Solvent The solvent for the ink is preferably an organic solvent in terms of excellent storage stability and low light loss. From the above viewpoint, the organic solvent is preferably alcohol. From the above viewpoint, the number of carbon atoms in the organic solvent is preferably 1 or more and 7 or less, more preferably 2 or more, more preferably 5 or less, or 4 or less, and most preferably 2. Solvents include water, propylene glycol monomethyl ether acetate, 3-methoxy-3-methyl-butyl acetate, ethoxyethyl propionate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol tertiary Butyl ether, dipropylene glycol monomethyl ether, ethylene glycol butyl ether, ethylene glycol ethyl ether, ethylene glycol methyl ether, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2-pentanediol, 2-methylpentane-2 ,4-diol, 2,5-hexanediol, 2,4-heptanediol, 2-ethylhexane-1,3-diol, diethylene glycol, hexanediol, octanediol, triethylene glycol, tri-1,2-propylene glycol , glycerol, ethylene glycol monohexyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, ethylene glycol monobutyl acetate, diethylene glycol monoethyl ether acetate, methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, 2-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, 2-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, 1- hexanol, 2-hexanol, 2-ethylbutanol, 1-heptanol, 2-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, 2-octanol, n-nonyl alcohol, 2,6 dimethyl-4-heptanol, n-decanol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol, etc., and from the viewpoint of excellent storage stability and low light loss, methanol, ethanol , propanol, butanol, pentanol, hexanol, heptanol, and isomers thereof are more preferred, ethanol, propanol, butanol and isomers thereof are more preferred, and ethanol is most preferred.

2.2.2.4. Dispersant The dispersant is not particularly limited, but includes, for example, a dispersant that non-covalently bonds or interacts with the metal component, and a dispersant that covalently bonds with the metal component. Non-covalently bonding or interacting functional groups include dispersants having phosphate groups. By using such a dispersant, the dispersibility of the metal component tends to be further improved.

2.3. Plasma Reaction Step In the plasma reaction step, the precursor thin film obtained as described above is exposed to a gas containing both hydrogen atoms and oxygen atoms at a partial pressure of 10 to 1000 Pa for 180 to 2000 seconds. It is a step of obtaining a conductive sheet by reacting with plasma during a period of time. As a result, the precursor thin film is fired, and the metal particles in the ink are sintered together to form a particle layer (conductive thin film). , so that the penetration portion A can be formed. By forming the penetration part A, the conductive sheet becomes excellent in information extraction prevention functionality.

Furthermore, by going through this manufacturing process, pore growth progresses between the particle layer and the base material, forming relatively large pores, which is advantageous for the formation of unevenness in which the infiltration part B is likely to be formed on the surface of the particle layer. can be done. As a result, it is possible to obtain a conductive sheet that is even more excellent in information extraction prevention functionality. It should be noted that the concentration of oxygen contained in the conductive sheet can also be adjusted by including molecules containing both hydrogen atoms and oxygen atoms in the atmosphere during the plasma reaction.

Plasma can be generated by various methods. Among them, microwave plasma and high-frequency plasma are preferred because they are relatively easy to control, and microwave plasma is more preferred from the viewpoint of reducing contamination caused by electrodes for plasma generation in the apparatus.

The microwave power in the microwave plasma is preferably 0.5-10 kW, more preferably 0.5-5.0 kW. When the microwave output is 0.5 kW or more, the information extraction prevention functionality is further improved, and the plasma reaction time can be shortened. Further, when the microwave output is 10 kW or less, etching or denaturation of the base material by the plasma tends to be suppressed.

The plasma reaction treatment time is 180 to 2000 seconds, preferably 200 to 1000 seconds, more preferably 220 to 500 seconds. When the treatment time is 180 seconds or more, a particle layer is formed, and pore growth progresses between the particle layer and the base material to form relatively large pores, making it easier to form the infiltration portion A. Also on the surface of the particle layer, irregularities are formed in which the intrusion portion B is likely to be formed, thereby further improving the information extraction prevention functionality. Moreover, since the treatment time is 2000 seconds or less, the productivity of the conductive sheet tends to be further improved.

The plasma reaction atmosphere includes a gas containing molecules containing both hydrogen atoms and oxygen atoms, and optionally noble gases. The partial pressure of the gas containing molecules containing both hydrogen atoms and oxygen atoms is preferably 10-1000 Pa, more preferably 50-500 Pa, still more preferably 75-300 Pa. When the partial pressure of the gas containing molecules containing both hydrogen atoms and oxygen atoms is 10 Pa or more, the increase in pores between the particle layer and the base material progresses and relatively large pores are formed and permeate. In addition to making it easier to form the portion A, unevenness is formed on the surface of the particle layer to facilitate the formation of the intruding portion B, thereby further improving the information extraction prevention functionality.

The gas containing molecules containing both hydrogen atoms and oxygen atoms is not particularly limited, but examples thereof include water molecules, organic alcohol molecules, organic ether molecules, organic ester molecules, organic aldehyde molecules, and the like. By using such a gas as the atmosphere of the plasma reaction process, the growth of the sintered particles proceeds while, for example, the copper oxide contained in the ink is reduced. In addition, along with this, pore growth progresses between the particle layer and the base material, forming relatively large pores, making it easier to form the penetrating portion A, and also forming the penetrating portion B on the surface of the particle layer. Easy unevenness is formed, thereby further improving the information extraction prevention functionality. Furthermore, there is a tendency for the conductivity of the manufactured conductive sheet to be further improved. In particular, it is most preferable to use a gas containing molecules containing both hydrogen atoms and oxygen atoms as water molecules from the viewpoint of less harm to the human body and less risk of explosion when leaked. The molecules containing both hydrogen atoms and oxygen atoms contained in this gas may be of one type or of a plurality of types.

Examples of rare gases include, but are not limited to, helium, argon, xenon, and krypton. Among these, helium or argon, which has a relatively small molecular weight, is preferred, and helium is most preferred, from the viewpoint of less sample etching by these plasmas. Using such a rare gas makes it easier to control the plasma reaction.

The above gases may be mixed and used, and other gases may be further mixed and used.

The pressure of the plasma reaction may be under increased pressure, under reduced pressure, or under atmospheric pressure. Among these, from the viewpoint of lengthening the mean free path of plasma, it is preferable to be under reduced pressure. Specifically, the pressure is preferably 0.1-1000 Pa, more preferably 1.0-500 Pa, still more preferably 10-300 Pa. When the pressure is 0.1 Pa or more, the mean free path of plasma tends to become longer. Moreover, since the pressure is 1000 Pa, more reducing gases and rare gases can be used.

The plasma reaction step in this embodiment is preferably applied to the precursor thin film forming a continuous pattern with openings. As a result, the plasma reaction progresses in the precursor thin film further exposed by the opening, which is advantageous for the particle layer and the substrate to have a specific adhesiveness, thereby forming the infiltration portion A. Become. That is, it is advantageous for manufacturing a conductive sheet having an infiltration portion A and having excellent information extraction prevention functionality. In addition, relatively large pores are formed as pores increase between the particle layer and the base material, and such pores can also contribute to the formation of the infiltration portion A.

The mechanism by which this information extraction prevention functionality is excellent is not limited to the following, but the plasma reaction progresses in the precursor thin film further exposed by the openings, thereby increasing the vacancy increase speed. In addition, the temperature at the interface between the base material and the precursor thin film rises due to the heat of the plasma reaction, compared to when there are no openings. This reduces the contact rate between the base material and the particle layer, improving the information extraction prevention functionality. can be considered.

The opening ratio of the precursor thin film, which constitutes a continuous pattern having openings, is preferably 20 to 99%, more preferably 30 to 97%, still more preferably 50 to 95%. As the aperture ratio increases, the information extraction prevention functionality of the particle layer 10 tends to be further improved. Also, the sheet resistance of the particle layer 10 tends to decrease as the aperture ratio decreases.

The "aperture ratio of the precursor thin film" can be calculated by the following formula for the region on the substrate where the precursor thin film pattern is formed. The region on the substrate where the precursor thin film pattern is formed excludes the edges where the precursor thin film pattern is not formed.
Aperture ratio of precursor thin film pattern = (1-area occupied by precursor thin film pattern/area of substrate) x 100

Although the continuous pattern having openings is not particularly limited, for example, a pattern in which a plurality of fine lines intersect is preferable. In this case, the fine lines correspond to the precursor thin film, and the gaps between the fine lines are the openings.

A precursor thin-line pattern can be formed on the precursor thin film in the same manner as the pattern formed by the plurality of metal fine lines described above. In addition, the precursor thin wire means a precursor thin film having a thin wire shape, and the precursor thin wire pattern means a pattern formed by a plurality of precursor thin wires.

2.3.1. Line Width The line width of the precursor thin line is preferably 100 nm to 1000 μm, more preferably 200 nm to 500 μm, still more preferably 300 nm to 100 μm, even more preferably 400 nm to 50 μm, still more preferably 500 nm to 5.0 μm.

When the width of the precursor thin wire is 100 nm or more, the metal thin wire produced through the plasma treatment process can have sufficient electrical conductivity, and the sheet resistance tends to be further reduced. In addition, it is possible to sufficiently suppress the decrease in electrical conductivity due to oxidation, corrosion, etc. of the surface of the fine metal wire. Furthermore, when the aperture ratio is the same, the finer the width of the precursor fine wires, the more the number of precursor fine wires can be increased. As a result, the electric field distribution of the conductive sheet becomes more uniform, making it possible to manufacture electronic devices with higher resolution.

On the other hand, when the width of the precursor fine wire is 5.0 μm or less, the visibility of the metal fine wire produced through the plasma treatment process is further reduced, and the conductive thin film and the conductive sheet comprising the same are more transparent. tend to improve.

2.3.2. Aspect Ratio The aspect ratio represented by the thickness T of the precursor fine wire to the width of the precursor fine wire is preferably 0.05 to 1.00, more preferably 0.08 to 0.90, and further It is preferably 0.10 to 0.80. When the width of the precursor thin wire is constant, the greater the aspect ratio, the more the electrical conductivity of the metal thin wire produced through the plasma treatment process tends to improve without lowering the transmittance. In addition, when the aspect ratio is 1.00 or less, there is a tendency to suppress decrease in transmittance due to excessive film thickness.

2.3.3. Pitch Pitch P is preferably 1.0 to 1000 μm, more preferably 5.0 to 500 μm, even more preferably 50 to 250 μm, still more preferably 100 to 250 μm. When the pitch P is 1.0 μm or more, the transparency of the conductive thin film manufactured through the plasma treatment process and the conductive sheet including the same tends to be further improved. Further, when the pitch P is 1000 μm or less, the conductivity tends to be further improved. When the shape of the fine metal line pattern is a mesh pattern, an aperture ratio of 99% can be obtained by setting the pitch of the fine metal line pattern having a line width of 1 μm to 200 μm.

The line width W, aspect ratio, and pitch P of the fine metal line pattern can be confirmed by observing the cross section of the conductive sheet with an electron microscope or the like. Also, the line width and pitch of the metal fine line pattern can be observed with a laser microscope or an optical microscope. Also, since the pitch P and the aperture ratio have a relational expression to be described later, if one is known, the other can be calculated. In addition, methods for adjusting the line width W, aspect ratio, and pitch P of the metal fine line pattern to desired ranges include a method for adjusting the grooves of a plate used in the method for manufacturing a conductive sheet described later, and a method for adjusting the grooves of the metal particles in the ink. and a method of adjusting the average particle size of the.

2.4. Lamination Step The lamination step is a step of laminating a protective layer on the substrate so as to cover the particle layer. Although the lamination method is not particularly limited, for example, a method of press-bonding the surface of the conductive sheet 100 on which the particle layer 10 is formed and the surface of the protective layer can be used.

Although the atmosphere in the lamination process is not limited, it can be carried out in the air or in an inert gas. In addition, it can be carried out under atmospheric pressure or under reduced pressure. Also, this lamination process can be performed at different temperatures. Lamination at room temperature is preferred from the viewpoint of simplicity.

3. Information Extraction Prevention Method The information extraction prevention method of the present embodiment has a peeling step of peeling off the protective layer from the substrate in the conductive sheet. Through this peeling step, the particle layer 10 is peeled off in a state of being adhered to the protective layer 30 side rather than the base material 20, and the particle layer 10 is cut. Therefore, when the particle layer 10 is, for example, an RFID transparent antenna, the antenna portion (the particle layer 10) is physically destroyed by peeling off, making it impossible to access the RFID semiconductor element, preventing information extraction. function is exhibited.

4. Antenna The antenna of the present embodiment is not particularly limited as long as it includes the conductive sheet. For example, an RF tag has a semiconductor element and an antenna connected thereto so that it can transmit and receive a specific frequency, and a conductive sheet can be used as the antenna. If the conductive sheet is made transparent, it becomes a transparent antenna.

FIG. 4 shows a perspective view showing one mode of an RF tag 300 having the conductive sheet of this embodiment as a transparent antenna. The RF tag 300 has a substrate 320, an antenna section 310 formed on the substrate 320, a semiconductor element 340 electrically connected to the antenna section 310, and a protective layer 330 covering the antenna section 310. . Antenna section 310 and semiconductor element 340 are electrically connected, and electricity generated by antenna section 310 in response to a predetermined frequency is collected toward semiconductor element 330 . Here, the antenna section 310, the base material 320, and the protective layer 330 correspond to the particle layer 10, the base material 20, and the protective layer 30, respectively.

5. Touch panel In the above description, the conductive sheet of the present embodiment is used as a transparent antenna of the RF tag 300 to prevent information extraction. Instead, it can also be used for touch panels and other uses, which will be described later.

In these applications, by separating the base material portion and the particle layer portion containing metal by utilizing the releasability of the base material and the particle layer of the conductive sheet of the present embodiment, the articles for each use are discarded. It is possible to improve the recyclability at the time of disposal and make it possible to consider the environment of the waste.

In addition, by utilizing the releasability of the base material and the particle layer, it is possible to achieve macro-patterning by the particle layer in articles for various uses, and to improve the degree of freedom in designing the article. For example, a portion cut out of the particle layer by a cutter or the like can be selectively used as an insulating portion.

Note that the RF tag 300 can also exhibit the above-described recyclability and patterning ability by using the conductive sheet of the present embodiment.

The conductive sheet of this embodiment can also be used for purposes other than antennas. For example, the touch panel of the present embodiment is not particularly limited as long as it includes the conductive sheet. For example, in a capacitive touch panel, two conductive sheets are present on the front and back surfaces of an insulator, and the two conductive sheets face each other such that line patterns of thin metal wires, for example, intersect. The conductive sheet is connected to an extraction electrode, and the extraction electrode connects the fine metal wire and a controller (such as a CPU) for switching the energization of the fine metal wire.

Note that the touch panel of the present embodiment is not limited to the capacitive type, and may be of a resistive film type, a projection type capacitive type, a surface type capacitive type, or the like.

6. Display The display of the present embodiment is not particularly limited as long as it includes the conductive sheet. For example, an organic electroluminescence (EL) display has a structure in which an organic EL film is sandwiched between electrodes, and the conductive sheet can be used as one of the electrodes. Further, a liquid crystal display has a structure in which a liquid crystal layer is sandwiched between electrodes, and the conductive sheet can be used as one of the electrodes.

7. Heater The heater of the present embodiment is not particularly limited as long as it includes the conductive sheet. For example, an electric heater has an electric heating part that generates Joule heat by supplying electricity and a power supply device that supplies electric power to the electric heating part, and a conductive sheet can be used as the electric heating part. If the conductive sheet is made transparent, the heater will be transparent, and if the conductive sheet is designed to have a high resistance, the heater will generate a large amount of heat.

For example, the use of the transparent heater is not particularly limited. Anti-fogging and anti-freezing heaters are included.

8. Electromagnetic Wave Shield The electromagnetic wave shield of the present embodiment is not particularly limited as long as it includes the conductive sheet. For example, an electromagnetic wave shield has a shielding material that reflects or absorbs incident electromagnetic waves, and the above conductive sheet can be used as the shielding material.

Hereinafter, the present invention will be described more specifically using examples and comparative examples. The present invention is by no means limited by the following examples.

(Morphological evaluation of thin film)
The obtained base material with a conductive thin film was cut out with a razor, embedded in a vapor-deposited carbon layer, and thinly sliced with a thickness of about 100 nm by a focal ion beam. Using the obtained thin section as a measurement sample, STEM-EDX analysis was performed by irradiating an electron beam under the following conditions to prepare an evaluation sample. The film thickness of the particle layer, the fact that the particle layer is a layer formed by sintering metal particles, the contact ratio, and the depths of the penetration portions A and B were obtained from this cross-sectional TEM image. The oxygen concentration of the thin film was determined by STEM-EDX analysis. Furthermore, the pattern shape, line width, pitch, etc. of the particle layer were evaluated with a laser microscope (OLS-4500 manufactured by OLYMPUS). FIG. 5 shows a cross-sectional photograph of Example 1. As shown in FIG.

[STEM-EDX equipment conditions]
STEM: Scanning transmission electron microscope HD-2300A manufactured by Hitachi High-Technologies Corporation
EDX: Energy dispersive X-ray spectrometer Octane T Plus (software: GENESIS) manufactured by EDAX
Accelerating voltage: 200 kV
Measurement magnification: 100,000 times Mapping elements: Cu, O, P, Si, C

(Information extraction prevention)
The protective layer of the conductive sheet prepared in Examples or Comparative Examples was peeled off from the PET sheet as the base material, and the presence or absence of transfer of the particle layer (fine metal wires) to the protective layer was confirmed. After peeling, the surface of the protective layer and the surface of the substrate were visually observed to confirm whether or not the fine metal wires had migrated to the protective layer side.
Information extraction prevention ◯: Migration of the particle layer to the protective layer was observed.
Information extraction prevention x: No migration of the particle layer to the protective layer was observed.

<Example 1>
(Preparation of transparent substrate)
Using polyethylene terephthalate (PET) as a transparent substrate, a surface layer forming composition containing silicon oxide nanoparticles and a conductive organic silane compound is applied thereon, and dried to obtain a thickness of 150 nm having an antistatic function. A substrate was obtained by forming a surface layer containing silicon oxide with a volume resistivity of 5000 Ωcm. This base material has a form in which a surface layer is laminated on PET as the base material.

(Ink preparation)
20 parts by mass of cuprous oxide nanoparticles with a primary particle size of 21 nm, 4 parts by mass of a dispersant (manufactured by Big Chemie, product name: Disperbyk-145), and a surfactant (manufactured by Seimi Chemical Co., product name: S-611 ) and 75 parts by mass of ethanol were mixed to prepare an ink containing 20% by mass of cuprous oxide nanoparticles.

(Precursor thin film forming step)
First, the ink was applied to the surface of the blanket, and then the surface of the blanket coated with the ink and the plate having the grooves of the fine metal line pattern were brought into contact with each other to transfer part of the ink on the surface of the blanket to the convex surface of the plate. After that, the surface of the blanket coated with the remaining ink was brought into contact with the substrate to transfer the ink in the shape of a metal fine line pattern onto the substrate. This step produced a precursor thin film. The thickness of this precursor thin film was 360 nm, the line width was 3 μm, and the pitch was 60 μm. Table 1 lists these results.

(Plasma reaction process)
The precursor thin film obtained as described above was subjected to a plasma reaction. Specifically, plasma was generated by microwaves generated at an output of 0.9 kW in an atmosphere with a partial pressure of water molecules of 100 Pa under reduced pressure, and the plasma and the precursor thin film were allowed to react for 180 seconds.

(Lamination process)
On the particle layer formed as described above, the adhesive surface of the Kapton tape was attached facing each other at 20° C., and a 2N (Newton) roller was reciprocated twice from above to form a protective layer. .

Each evaluation was performed on the conductive sheet of Example 1. These results are shown in Table 1.

<Example 2>
The same operation as in Example 1 was performed, except that the plasma reaction time to the precursor thin film was set to 300 seconds, and the adhesive surfaces of cellophane tape were attached facing each other instead of the Kapton tape. Table 1 shows the results.

<Comparative Example 1>
The same operation as in Example 1 was performed except that the plasma reaction time to the precursor thin film was 60 seconds. Table 1 shows the results.

DESCRIPTION OF SYMBOLS 10... Particle layer, 10'... Metal fine wire, 11... Pore, 20... Base material, 21... Elevation part, 30... Protective layer, 31... Penetration part, 40... Pattern, 50... Opening, 100... Conductive sheet, DESCRIPTION OF SYMBOLS 300... RFID tag, 310... Antenna part, 320... Base material, 330... Protective layer, 340... Semiconductor element

Claims (36)

a substrate;
a particle layer in which transition metal-containing particles are bonded and laminated on the substrate;
a protective layer laminated on the substrate so as to cover the particle layer;
A part of the protective layer has an infiltration part A that intrudes into the space between the particle layer and the base material,
conductive film. The particle layer has voids, and a portion of the protective layer has an infiltration portion B penetrating into the voids.
The conductive film according to claim 1. wherein the protective layer contains an organic substance;
The conductive film according to claim 1 or 2. wherein the protective layer comprises a polymer;
The conductive film according to claim 3. wherein the protective layer comprises polyisoprene;
The conductive film according to claim 3 or 4. wherein the protective layer comprises a silicon compound;
The conductive film according to any one of claims 1-5. The adhesive strength of the protective layer to the substrate is 0.5 to 5.0 N/cm,
The conductive film according to any one of claims 1-6. The protective layer has a thickness of 1 μm or more and 1 cm or less.
The conductive film according to any one of claims 1-7. The penetration portion A has a depth of 5.0 nm or more and 500 nm or less.
The conductive film according to any one of claims 1-8. The penetration portion B has a depth of 5.0 nm or more and 500 nm or less.
The conductive film according to any one of claims 1-9. The contact ratio between the substrate and the particle layer is 0% or more and 20% or less,
The conductive film according to any one of claims 1-10. The average atomic concentration of oxygen in the particle layer is 10% or less,
The conductive film according to any one of claims 1-11. the particle layer forms a continuous pattern with openings;
The conductive film according to any one of claims 1-12. wherein the pattern is a pattern composed of a plurality of intersecting fine lines;
The conductive film according to claim 13. The line width of the fine line is 100 nm or more and 1000 μm or less,
The conductive film according to claim 14. The fine wires have a pitch of 1.0 μm or more and 1000 μm or less.
The conductive film according to claim 14 or 15. The film thickness of the particle layer is 30 nm or more and 1000 μm or less,
The conductive film according to any one of claims 1-16. the substrate has a plurality of layers,
The conductive film according to any one of claims 1-17. The substrate has a surface layer containing a silicon compound,
The conductive film according to any one of claims 1-18. The base material is plastic,
The conductive film according to any one of claims 1-19. The plastic is polyethylene terephthalate,
The conductive film according to claim 20. wherein the transition metal comprises a metal of Group 11 elements of the IUPAC Periodic Table;
The conductive film according to any one of claims 1-21. wherein the transition metal comprises copper;
The conductive film according to claim 22. The average particle diameter of the particles constituting the particle layer is 1.0 nm or more and 500 nm or less.
The conductive film according to any one of claims 1-23. Visible light transmittance is 70% or more and 99% or less,
The conductive film according to any one of claims 1-24. Sheet resistance is 0.001 Ωcm ^-2 or more and 20 Ωcm ^-2 or less,
The conductive film according to any one of claims 1-25. Provided with the conductive film according to any one of claims 1 to 26,
touch panel. Provided with the conductive film according to any one of claims 1 to 26,
display. Provided with the conductive film according to any one of claims 1 to 26,
heater. Provided with the conductive film according to any one of claims 1 to 26,
electromagnetic shield. Provided with the conductive film according to any one of claims 1 to 26,
antenna. A film forming step of forming a precursor thin film on a substrate;
A plasma treatment step of reacting the precursor thin film with plasma for 180 seconds or more and 2000 seconds or less in the presence of a gas composed of molecules containing both hydrogen atoms and oxygen atoms at a partial pressure of 10 Pa to 1000 Pa to form a particle layer. When,
a lamination step of laminating a protective layer on the base material so as to cover the particle layer;
A method for producing a conductive film. the molecule containing both a hydrogen atom and an oxygen atom is a water molecule;
33. A method for producing a conductive sheet according to claim 32. wherein the precursor thin film forms a continuous pattern with openings;
34. A method for producing a conductive sheet according to claim 32 or 33. The opening ratio of the precursor thin film to the substrate is 20% or more and 99% or less,
A method for producing a conductive sheet according to any one of claims 32 to 34. Using microwave plasma in the plasma treatment step,
The method for producing a conductive film according to any one of claims 32-35.

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