JPH1098292A - Electromagnetic wave shielding material - Google Patents

Abstract

(57) [Problem] To provide a conventional electromagnetic shielding material for a display device, it is not possible to simultaneously suppress the deterioration of the image quality of the display device and achieve a high electromagnetic shielding effect. SOLUTION: The number of layers of the transparent conductive layer is two or more, using an electromagnetic wave shielding part composed of a transparent resin base material and a transparent conductive layer formed on one or both sides of the transparent resin base material. Reflectance in the region is less than 20%, 100MHz
An electromagnetic wave shielding material having the following electromagnetic wave shielding effect of 40 dB or more is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shielding material, and more particularly to an electromagnetic wave shielding material of a type in which a transparent conductive layer is formed on a transparent substrate.

[0002]

2. Description of the Related Art There are many devices using electronic, electric, and radio waves around us, and some of them emit unwanted electromagnetic waves unintentionally. This electromagnetic wave affects other electronic devices and causes malfunction, generation of noise, and other various functional failures. In addition, the influence of electromagnetic waves radiated from electronic devices on the human body has been a problem, and electric devices, information devices, and the like are particularly regulated in Europe and the like. In Japan, voluntary regulations have recently been established, and the necessity of shielding electromagnetic waves radiated from electric devices, information devices, and the like has been emphasized.

[0003] As a method of electromagnetic wave shielding, a method of forming a conductive film on the surface of a housing material or a casing material of an electronic device, a method of dispersing a conductive filler, in addition to the improvement of a circuit and the installation of a shield plate, have been used. A method of manufacturing a housing material or a casing material of an electronic device by using a resin, a method of manufacturing a housing material or a casing material of an electronic device by using a conductive composite material including a carbon fiber mat, a metal mesh, and a resin. I have.

Also, among electronic devices, in a display device such as a CRT (CRT) display or a color display plasma display, electromagnetic waves are radiated from a screen, and in these display devices, a user of the display device is in front of the screen of the display device. Therefore, it is necessary to sufficiently shield the electromagnetic waves radiated from the screen without deteriorating the image quality.

An electromagnetic wave shielding material for shielding an electromagnetic wave radiated from a screen of a display device (hereinafter, this electromagnetic wave shielding material is referred to as an “electromagnetic wave shielding material for a display device”) is used for (1) a display unit. If the glass is broken, prevent it from scattering, and (2) reduce the weight of the electromagnetic wave shielding material.
Since it is desirable to be excellent in shock absorption and light in weight, the electromagnetic wave shielding material is preferably a type in which a transparent conductive layer is formed on a transparent resin substrate (among others, a transparent resin film).

As such an electromagnetic wave shielding material for a display device, (1) a transparent film substrate is provided with a transparent conductive layer made of a metal or a transparent conductive oxide on one surface and an adhesive on the other surface. There are known ones in which a transparent substrate is adhered, and (2) two electromagnetic wave shielding materials of the above (1) which are laminated so that the transparent conductive layers are in contact with each other ((1), (2) 2) Both refer to JP-A-1-235195).

Although there is no specific description of an electromagnetic wave shielding material for a display device, JP-A-59-201494 discloses a transparent conductive thin film made of ITO and an electromagnetic conductive material different from the transparent conductive thin film. There is disclosed a transparent electromagnetic shielding member formed by alternately laminating a transparent thin film of a material having characteristic characteristics on a transparent substrate.

[0008]

When an electromagnetic wave shielding material for a display device in which a transparent conductive layer is formed on a transparent resin substrate is obtained, from the viewpoint of obtaining an electromagnetic wave shielding material having a high electromagnetic wave shielding effect, a transparent conductive material is required. The transparent conductive layer is preferably formed of a metal thin film having higher conductivity than the conductive oxide film.

However, when the transparent conductive layer is formed of a metal thin film, the light transmittance in the visible light region is reduced, so that a display device capable of shielding electromagnetic waves to a high degree while suppressing a decrease in image quality of the display device. It is difficult to obtain an electromagnetic wave shielding material for use.

On the other hand, when the transparent conductive layer is formed of a transparent conductive oxide film, an electromagnetic wave shielding material for a display device having a relatively high light transmittance in the visible light region can be obtained. It is easy to obtain an electromagnetic wave shielding material for a display device that can shield electromagnetic waves while suppressing deterioration in image quality of the device.

However, when a transparent conductive oxide film is formed on a transparent resin substrate, the transparent conductive oxide film is formed under a low temperature environment because the heat resistance of the transparent resin substrate is relatively low. It must be formed, and accordingly, the conductivity of the obtained transparent conductive oxide film decreases. Therefore, it is difficult to obtain a display device electromagnetic wave shielding material having a high electromagnetic wave shielding effect simply by forming a transparent conductive oxide film on a transparent resin substrate. Further, two electromagnetic wave shielding materials of a type in which a transparent conductive oxide film is formed on a transparent resin base material are laminated such that the transparent conductive layers are in contact with each other as in the case of the electromagnetic wave shielding material of (2). Can improve the electromagnetic wave shielding effect,
The degree of the improvement is only as much as the thickness of the transparent conductive layer is increased, and is not so high.

Furthermore, the conventional transparent conductive oxide film formed in a low temperature environment has a higher light transmittance in the visible light region than a metal thin film, but has a lower conductivity, and therefore has a higher light transmittance. In order to provide an electromagnetic wave shielding effect, the film thickness must be increased, and the light transmittance is reduced. Therefore, it is desired to further improve the light transmittance in the visible light region.

An object of the present invention is to provide an electromagnetic wave shielding material capable of highly shielding an electromagnetic wave radiated from a screen while suppressing deterioration in image quality even when used as an electromagnetic wave shielding material for a display device. .

[0014]

According to the present invention, there is provided an electromagnetic wave shielding material comprising a transparent resin substrate and a transparent conductive layer formed on one or both surfaces of the transparent resin substrate. Part, the number of transparent conductive layers is 2 or more, and the reflectance in the visible light region is 20% or less,
It is characterized in that the shielding effect against electromagnetic waves of MHz or less is 40 dB or more (hereinafter, this electromagnetic wave shielding material is referred to as “electromagnetic wave shielding material I”).

According to another aspect of the present invention, there is provided an electromagnetic wave shielding material comprising at least one of indium (In), zinc (Zn), gallium (Ga) and oxygen (O) on one surface of a transparent resin substrate. A transparent conductive layer made of a transparent conductive oxide film as an element, and an electrically insulating layer made of a transparent electrically insulating material having a different refractive index from the transparent conductive layer are alternately laminated, and the transparent conductive layer The number of layers is 2 or more, the reflectance in the visible light region is 20% or less, and the shielding effect against electromagnetic waves of 100 MHz or less is 40 dB or more (hereinafter, this electromagnetic wave shielding material is referred to as “electromagnetic wave shielding material”). II ").

[0016]

Embodiments of the present invention will be described below in detail. First, the electromagnetic wave shielding material I of the present invention will be described. The electromagnetic wave shielding material I is, as described above, an electromagnetic wave comprising a transparent resin substrate and a transparent conductive layer formed on one or both surfaces of the transparent resin substrate. It has a shield part.

Here, as the transparent resin substrate, even when the electromagnetic wave shielding material I of the present invention is used as an electromagnetic wave shielding material for a display device, the deterioration of the image quality of the display screen can be suppressed as much as possible. Visible light (wavelength 380
It means light of ７780 nm. same as below. It is preferable to use those having a total light transmittance of about 70% or more. Total light transmittance of visible light in the transparent resin substrate,
It is more preferably about 75% or more, and about 80%
It is particularly preferable that the above is satisfied.

Specific examples of the material of the transparent resin substrate include polycarbonate resin, polyarylate resin, polyester resin such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone resin, amorphous polyolefin resin, polystyrene resin, and acrylic resin. No. Further, as a transparent resin substrate, a material having a near-infrared cut function, that is, a wavelength in the near-infrared region by adding a near-infrared absorber to prevent malfunction of a remote controller for a television or the like. 800-120
One having a reduced light transmittance at 0 nm can also be used. When the electromagnetic wave shielding material I of the present invention is used as an electromagnetic wave shielding material for a display device, it is preferable to use a transparent resin substrate having the near infrared cut function.

The thickness of the transparent resin substrate described above can be appropriately selected according to the intended use of the electromagnetic wave shielding material I and the like. In addition, the above-mentioned transparent resin base material, an undercoat layer for improving adhesion with a transparent conductive layer described later,
A hard coat layer to prevent the substrate from being damaged,
An antireflection layer or the like for improving transparency may be provided on one or both surfaces.

On the other hand, as the transparent conductive layer formed on one or both surfaces of the above-mentioned transparent resin substrate, indium oxide, ITO, tin oxide, antimony-doped tin oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, made of a transparent conductive oxide such as in ₂ O ₃ -ZnO-based amorphous oxide are preferred. Among these transparent conductive layers, in order to obtain an electromagnetic wave shielding material I having a desired electromagnetic wave shielding effect, a sheet resistance of 4
A transparent conductive oxide film having a resistance of 0 Ω / □ or less is preferable, and a transparent conductive oxide film having a sheet resistance of 30 Ω / □ or less is particularly preferable. In order to obtain a transparent conductive oxide film having a sheet resistance of 40 Ω / □ or less, the material is preferably an In ₂ O ₃ —ZnO-based amorphous oxide.

The term “In ₂ O ₃ —ZnO-based amorphous oxide” used in the present invention refers to indium (In), zinc (Z
It means an amorphous oxide in which n) and oxygen (O) are essential constituent elements, and gallium (Ga) and Sn are optional constituent elements.

When the above-mentioned In ₂ O ₃ -ZnO-based amorphous oxide is composed of only essential constituent elements excluding inevitable contaminants, the atomic ratio of indium (In) in the amorphous oxide is In / (In + Zn) is preferably 0.5 to 0.9 from the viewpoint of the conductivity of the obtained film, and 0.6 to 0.9.
0.9 is more preferable, and 0.8 to 0.9 is particularly preferable. In this case, the In ₂ O ₃ —Zn
The specific resistance of the film made of the O-based amorphous oxide is approximately 3 × 10 ^−4.
５5 × 10 ⁻⁴ Ω · cm.
When the thickness is 50 Å or more, a transparent conductive layer having a sheet resistance of 40 Ω / □ or less can be formed. The indium atomic ratio In / (In +
If Zn) is less than 0.5, the conductivity of the obtained film decreases,
If it exceeds 0.9, the resistance stability of the film to heat decreases.

On the other hand, when an arbitrary constituent element is contained in the In ₂ O ₃ —ZnO-based amorphous oxide, gallium (Ga) is particularly preferable as the optional constituent element. By containing gallium (Ga), an In ₂ O ₃ -ZnO-based amorphous oxide film with improved light transmittance at a wavelength of about 400 nm can be obtained.

When gallium (Ga) is included as an optional constituent element, the atomic ratio In / (In + Zn + Ga) of indium (In) in the amorphous oxide is In ₂ O ₃ − For the same reason as in the ZnO-based amorphous oxide film, it is preferably 0.5 to 0.9, more preferably 0.6 to 0.9, and more preferably 0.8 to 0.9. Is particularly preferred. Also,
Gallium (Ga) atomic ratio Ga / (In + Zn + Ga)
Is preferably at most 0.04, more preferably at most 0.03, particularly preferably at most 0.025. In this case, since the specific resistance of the film made of the amorphous oxide is approximately 3 × 10 ^{−4 to} 5 × 10 ⁻⁴ Ω · cm, the sheet resistance is set to approximately 1250 Å or more. Can form a transparent conductive layer having a resistivity of 40Ω / □ or less. The gallium (Ga) atomic ratio Ga / (In + Zn + Ga) is 0.0
When it exceeds 4, the conductivity of the obtained film is reduced.

[0025] When a film was formed by a In ₂ O ₃ -ZnO-based amorphous oxide film generally under 100 ° C. or lower temperature environment consisting of the, the In ₂ O ₃ -ZnO-based amorphous oxide film Transparency of other transparent conductive oxide films (indium oxide film, ITO film, tin oxide film, antimony-doped tin oxide, fluorine-doped tin oxide film, aluminum-doped zinc oxide formed under low temperature environment Material film etc.). Accordingly, the In ₂ O ₃ -ZnO-based amorphous oxide film is suitable for obtaining an electromagnetic wave shielding material having a high electromagnetic wave shielding effect, and also suitable for obtaining a highly transparent electromagnetic wave shielding material.

The electromagnetic wave shielding material I of the present invention having an electromagnetic wave shielding portion comprising the above-mentioned transparent resin base material and the above-mentioned transparent conductive layer formed on one or both surfaces of the transparent resin base material, May be provided with only one electromagnetic wave shield part, or a plurality of the electromagnetic wave shield parts may be overlapped. However, in any case, the number of the transparent conductive layers described above is two or more.

Here, the expression “the number of transparent conductive layers is two or more” in the present invention means that an electric insulating layer (including a transparent resin base material) is interposed when viewed in the thickness direction of the electromagnetic wave shielding material. Means that the number of transparent conductive layers adjacent to each other (the transparent conductive layer described above; this transparent conductive layer is formed on the surface of the transparent resin substrate described above) is two or more. Therefore, when two or more transparent conductive layers are in surface contact with each other when viewed in the thickness direction of the electromagnetic wave shielding material, the “number of transparent conductive layers” is one.

When the electromagnetic wave shielding material I of the present invention has only one electromagnetic wave shielding portion, the electromagnetic wave shielding portion has the transparent conductive layers formed on both surfaces of the transparent resin base material. (Hereinafter, this electromagnetic wave shield portion is referred to as “electromagnetic wave shield portion A”). In this case, the material, thickness, electrical characteristics, and optical characteristics of each transparent conductive layer may be the same or different.

When a plurality of the above-mentioned electromagnetic wave shield portions are superimposed on the electromagnetic wave shield member I of the present invention, each of the superposed electromagnetic wave shield portions may be the above-mentioned electromagnetic wave shield portion A, The above-mentioned transparent conductive layer may be formed on one surface of the above-mentioned transparent resin base material (hereinafter, this electromagnetic wave shield portion is referred to as “electromagnetic wave shield portion B”). Also in this case, the material, thickness, electrical characteristics, and optical characteristics of the transparent conductive layer in each electromagnetic wave shield may be the same or different.

However, if the total number of the electromagnetic wave shielding portions to be superimposed is 4 or more, the light transmittance of the obtained electromagnetic wave shielding material in the visible light region is likely to be reduced. The electromagnetic wave shield can be superposed by a method such as thermocompression bonding or use of double-sided tape. However, electrical insulation such as epoxy adhesive, acrylic adhesive, silicone adhesive, urethane adhesive, etc. It is practically preferable to use an adhesive.

When the electromagnetic wave shield portions are overlapped, the size of the electromagnetic wave shield portion to be overlaid (the size in plan view) is slightly smaller than the size of the electromagnetic wave shield portion thereunder (the size in plan view). It is preferable to make it smaller. Adjusting the size of the electromagnetic wave shield portion in this manner facilitates grounding from each transparent conductive layer after overlapping.

The electromagnetic shielding material I of the present invention can be obtained by appropriately using the electromagnetic shielding portion A and / or the electromagnetic shielding portion B so that the number of the transparent conductive layers is two or more. However, when an electromagnetic wave shielding material having a reflectance of more than 20% in a visible light region (meaning a wavelength range of 380 to 780 nm; the same applies hereinafter) is used as an electromagnetic wave shielding material for a display device, the image quality of the display device is reduced. The reflectivity is set to 20% or less in the electromagnetic wave shielding material I of the present invention because the reflectivity tends to decrease. The reflectance is preferably 15% or less, more preferably 10% or less.

The reflectivity in the visible light range depends on the material and thickness of the transparent resin base material constituting the electromagnetic wave shielding portion, the material and thickness of the transparent conductive layer, the number of interfaces in the electromagnetic wave shielding material, and the like. Change. For this reason, using the above-mentioned electromagnetic wave shield part A alone, or using a plurality of them, or using a plurality of the aforementioned electromagnetic wave shield parts B,
Alternatively, if an electromagnetic shielding material having two or more transparent conductive layers is manufactured by using a predetermined number of the electromagnetic shielding portions A and B in combination with each other, the reflectivity in the visible light region is necessarily 20%.
% Or less of the electromagnetic shielding material cannot be obtained. Therefore, the material and the thickness of the transparent resin base material, the material and the thickness of the transparent conductive layer, and the electromagnetic wave shielding material constituting the electromagnetic wave shielding portion are set so that the reflectance in the visible light region becomes a desired value of 20% or less. The number and the like of the inside interface are appropriately adjusted.

However, the reflectivity (the above-mentioned reflectivity) of the electromagnetic wave shielding material obtained by appropriately using the electromagnetic wave shield part A and / or the electromagnetic wave shield part B so that the number of transparent conductive layers becomes two or more is 20. %, By forming an antireflection layer for visible light on one or both surfaces of the electromagnetic wave shielding material, the reflectivity in the visible light region is reduced to 20%.
It can be: This antireflection layer is, for example, an antireflection film, that is, a predetermined dielectric multilayer film or a layer for antireflection (a layer formed by adding a titanium component to a siloxane oligomer,
(A fluorine-based acrylic resin layer) can be formed.

The antireflection layer for visible light has a reflectance of 2 in the visible light region even if the antireflection layer is not provided.
It may be used to further reduce the reflectance of an electromagnetic wave shielding material of 0% or less. The average transmittance of visible light in the electromagnetic wave shielding material I of the present invention having a reflectance in the visible light region of 20% or less is approximately 50% or more.

When an electromagnetic wave shielding material having a shielding effect of less than 40 dB for an electromagnetic wave having a frequency of approximately 10 to 100 MHz is used as an electromagnetic wave shielding material for a display device, particularly, an electromagnetic wave shielding material for a color display plasma display, radiation is emitted from a screen. Since it becomes difficult to sufficiently shield electromagnetic waves, the shielding effect of the electromagnetic wave shielding material I of the present invention for electromagnetic waves of 100 MHz or less is 40 d.
B or more. The electromagnetic wave shielding effect is preferably at least 45 dB, more preferably at least 50 dB. Here, the “electromagnetic wave of 100 MHz or less” in the present invention means an electromagnetic wave having a frequency of approximately 10 to 100 MHz.

The above-mentioned electromagnetic wave shielding effect changes according to the conductivity of the transparent conductive layer constituting the electromagnetic wave shielding portion, the number of transparent conductive layers, and the like. For this reason, the above-described electromagnetic wave shield portion A is used alone, or a plurality of electromagnetic wave shield portions B are used.
When an electromagnetic wave shielding material having two or more transparent conductive layers is produced by using a predetermined number of them at a time, an electromagnetic wave shielding material having an electromagnetic wave shielding effect of 40 dB or more cannot always be obtained. Therefore, the electromagnetic wave shielding effect is 40 dB.
The conductivity (material and thickness) of the transparent conductive layer constituting the electromagnetic wave shielding portion, the number of transparent conductive layers, and the like are appropriately adjusted so as to have the above desired values.

As described above, the sheet resistance is 40Ω / □.
By forming a transparent conductive layer with a transparent conductive oxide film having high conductivity as described below, an electromagnetic wave shielding effect of 40
It becomes easy to obtain an electromagnetic wave shielding material of dB or more.
Further, in the electromagnetic wave shielding material I of the present invention, since the number of transparent conductive layers is two or more, the number of times of electromagnetic wave reflection is increased as compared with an electromagnetic wave shielding material having one transparent conductive layer, and as a result, Even if the transparent conductive layer is formed of a transparent conductive oxide film such as indium oxide, ITO, tin oxide, antimony-doped tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide, the electromagnetic wave shielding effect is 40 dB. It is possible to obtain the above electromagnetic wave shielding material.

The electromagnetic wave shielding material I of the present invention is used as the outermost layer on one or both surfaces, and when the electromagnetic wave shielding material has the above-described antireflection layer for visible light, it is located immediately inside the outermost layer. May have a near-infrared cut layer for preventing malfunction of a remote controller for a television or the like. The near-infrared cut layer is formed, for example, by adding a near-infrared absorber to a near-infrared region having a wavelength of 80 nm.
Formed by coating a transparent resin composition having a reduced light transmittance at 0 to 1200 nm, or by attaching a transparent resin film (near infrared cut film) coated with the transparent resin composition. can do.

The electromagnetic shielding material I of the present invention described above.
Means that the reflectance in the visible light region is 20% or less and 100 MHz
Since the following electromagnetic wave shielding effect is 40 dB or more, even when used as an electromagnetic wave shielding material for a display device, the electromagnetic wave radiated from the screen of the display device can be highly shielded while suppressing deterioration in image quality. The electromagnetic wave shielding material I of the present invention can be used not only as an electromagnetic wave shielding material for various display devices that emit electromagnetic waves, but also as an electromagnetic wave shielding material for window glasses, pachinko machines (game tables), and the like.

The electromagnetic wave shielding material I of the present invention having such characteristics can be obtained by forming a transparent conductive layer on one or both surfaces of a transparent resin base material to form a desired electromagnetic wave shielding portion (the electromagnetic wave shielding portion A and / or the electromagnetic wave shielding portion). A required number of parts B) are produced, and if necessary, a predetermined number of electromagnetic wave shield parts A and / or electromagnetic wave shield parts B are overlapped by a desired method, and then, if necessary, an antireflection layer for visible light and / or Or by forming a near infrared cut layer,
Obtainable.

In forming a transparent conductive layer on a transparent resin substrate, a physical vapor deposition method such as a sputtering method (including a reactive sputtering method; the same applies hereinafter), an ion plating method, an activated vapor deposition method and the like. A chemical vapor deposition method such as a plasma CVD method or the like, a spray pyrolysis method, a sol-gel method, or the like can be appropriately applied according to the composition of the transparent conductive layer intended.

When a transparent conductive layer is formed on both surfaces of the transparent resin substrate, a transparent conductive layer is first formed on one surface of the transparent resin substrate, and the protective film is covered with the laminator so as to cover the transparent conductive layer. After laminating, a transparent conductive layer is preferably formed on the other surface of the transparent resin substrate. The protective film used at this time is preferably a film made of polyethylene, polypropylene, polyethylene terephthalate, etc., provided with a thin adhesive layer on one side, and is used for forming a transparent conductive layer on the other side of the transparent resin substrate. Which does not substantially generate gas. When a protective film that generates gas is used to form the transparent conductive layer on the other surface of the transparent resin substrate, bubbles are generated between the protective film and the transparent conductive layer (the base of the protective film). Therefore, when the film is continuously formed by the roll-to-roll method, uneven winding of the product occurs.

When the transparent conductive layer is to be formed from the above-described In ₂ O ₃ -ZnO-based amorphous oxide, the transparent conductive layer having excellent uniformity and excellent adhesion to the transparent resin substrate is used. After forming the film layer, it is preferable to apply a sputtering method or an ion plating method.

Hereinafter, In ₂ O ₃
-Film-forming conditions for forming a transparent conductive layer made of a ZnO-based amorphous oxide (however, composed of essential constituent elements) will be described in detail.

First, a sputtering target to be used may be a metal target or an oxide sintered body target as long as a transparent conductive film (oxide film) having a desired composition can be formed. However, it is preferable to use an oxide sintered body target according to the intended composition of the transparent conductive layer. Here, “the oxide sintered body target according to the composition of the target transparent conductive layer” means an oxide sintered body target having a composition that can obtain the transparent conductive layer having the target composition.

The composition of the above oxide sintered body target is as follows:
It is appropriately selected according to the sputtering rate and the intended composition of the transparent conductive layer. Indium (In) atomic ratio In /
In ₂ O ₃ -Zn in which (In + Zn) is 0.5 to 0.9
In forming the O-based amorphous oxide film, it is preferable to use an oxide sintered body target having an indium (In) atomic ratio of 0.45 to 0.85. As an oxide sintered body target, for example, indium (In)
Except that the range of the atomic ratio In / (In + Zn) is different, the sputtering target described in the 27th to 28th stages of JP-A-7-235219 can be used.

At this time, the relative density of the oxide sintered body target is preferably at least 90%, more preferably at least 95%, particularly preferably at least 97%. 90% relative density of oxide sintered compact target
If it is less than 1, the film-forming speed tends to be low, and the quality of the obtained film tends to be low. Here, the relative density indicates the actual density of the sintered body with respect to the theoretical density calculated from the composition of the oxide in terms of area fraction.

The purity of the raw material used for obtaining the oxide sintered body target is preferably at least 99%, more preferably at least 99.9%, and more preferably at least 99.9%.
It is particularly preferred that the content be 99% or more. If the purity of the raw material is less than 99%, the conductivity and chemical stability of the obtained film are likely to be reduced by impurities contained in the raw material.

The sputtering may be performed in one unit,
It may be multiple. Various methods such as RF sputtering and DC sputtering can be applied as the sputtering method. However, from the viewpoint of productivity and film characteristics of the obtained oxide film, generally, DC magnetron sputtering is generally used industrially. Is preferred. An example of DC magnetron sputtering conditions is as follows.

Attained vacuum degree Before sputtering, the inside of the vacuum chamber is set to 1 × 10 ^-4 in advance.
Vacuum to below Pa. During evacuation, heating may be performed to shorten the evacuation time. If the ultimate vacuum degree is higher than 1 × 10 ⁻⁴ Pa, it is difficult to sufficiently remove moisture adsorbed on the apparatus, the substrate (transparent resin substrate), the sputtering target, and the like. As a result, the conductivity of the obtained film tends to decrease.

The degree of vacuum at the time of film formation The degree of vacuum at the time of film formation is 1 × 10 ^-2 to 1 × 10 ⁰ Pa, preferably 1 × 10 ^{-2 to} 5 × 10 ^-1 Pa, particularly preferably 1 × 10 ^-2 Pa.
It is set to 10 ^{−2 to} 2 × 10 ⁻¹ Pa. The degree of vacuum during film formation is 1 ×
If the pressure is lower than 10 ^-2 Pa, the discharge stability decreases, and 1 ×
Be 10 ⁰ higher the voltage applied to the is high pressure sputtering target from Pa becomes difficult.

The output during film formation The output during film formation is 3 W / cm ² or less, preferably 2 W / c.
m ² or less, particularly preferably 1 W / cm ² or less, and the voltage at this time is 100 to 400 V, preferably 100 to 3 V.
00V, particularly preferably 100 to 200V. If the output during film formation exceeds 3 W / cm ² , it becomes difficult to obtain a dense film, and as a result, the conductivity of the obtained film tends to decrease.

Atmosphere gas As the atmosphere gas, a mixed gas of an inert gas such as an argon gas and an oxygen gas is usually used. The mixing ratio of the inert gas and the oxygen gas varies depending on the oxidation state of the sputtering target used, the pressure at the time of film formation, the output at the time of film formation, etc., but the mixing ratio of the oxygen gas is 5% or less by volume concentration. Is preferably set to 4% or less, more preferably 3% or less. When the mixing ratio of the oxygen gas exceeds 5% by volume, the conductivity of the obtained film tends to decrease. The purity of the mixed gas is 99.9.
%, More preferably at least 99.95%, particularly preferably at least 99.99%.

Substrate Temperature The substrate (transparent resin substrate) does not need to be heated, but may be heated if necessary. When the substrate is heated, the temperature is appropriately selected according to the heat resistance of the transparent resin substrate within a temperature range at which the substrate does not deform or deteriorate due to heat. The substrate temperature is preferably about 20 to 150 ° C., more preferably about 20 to 100 ° C., and 2
It is particularly preferable to set the temperature to 0 to 80 ° C.

The transparent conductive layer made of an In ₂ O ₃ —ZnO-based amorphous oxide (which is composed of essential constituent elements) is formed by a method such as DC magnetron sputtering under the conditions exemplified above. However, a transparent conductive layer made of an In ₂ O ₃ —ZnO-based amorphous oxide containing any constituent element can also be formed in a similar manner.

Gallium (G) is used as the optional constituent element.
a) and containing only indium (In)
n / (In + Zn + Ga) is 0.5 to 0.9 and gallium (Ga) atomic ratio Ga / (In + Zn + Ga) is 0.0.
When a transparent conductive layer made of an In ₂ O ₃ -ZnO-based amorphous oxide of 4 or less is formed by DC magnetron sputtering, the indium (In) atomic ratio In /
(In + Zn + Ga) is 0.45 to 0.85, and the gallium (Ga) atomic ratio Ga / (In + Zn + Ga) is 0.15.
It is preferable to use an oxide sintered body target of not more than 04.

Next, the electromagnetic wave shielding material II of the present invention will be described. As described above, the electromagnetic wave shielding material II of the present invention has indium (In),
A transparent conductive layer made of a transparent conductive oxide film containing zinc (Zn), gallium (Ga), and oxygen (O) as constituent elements; and an electricity made of a transparent electrically insulating material having a different refractive index from the transparent conductive layer. Insulating layers are alternately laminated, the number of the transparent conductive layers is 2 or more, the reflectance in the visible light region is 20% or less, and the shielding effect against electromagnetic waves of 100 MHz or less is 40 dB or more. Is what you do.

Here, as the transparent resin substrate, the same transparent resin substrate as described in the description of the electromagnetic wave shielding material I of the present invention can be used. Further, the above-mentioned transparent conductive oxide film is made of only indium (In), zinc (Zn), gallium (Ga) and oxygen (O) except for inevitable contaminants. The transparent conductive oxide film may be any material as long as the electromagnetic wave shielding material II having an intended reflectance (reflectance in a visible light region) and an electromagnetic wave shielding effect can be obtained, and its sheet resistance is 40Ω / □ or less. And particularly preferably 30
It is preferably Ω / □ or less.

In order to obtain a transparent conductive oxide film having a sheet resistance of 40 Ω / □ or less, the transparent conductive oxide film should be an amorphous film (hereinafter, this amorphous film is referred to as “transparent conductive oxide film”). Amorphous oxide film ”), and the atomic ratio In / (In + Zn + Ga) of indium (In) is 0.5.
0.9, gallium (Ga) atomic ratio Ga / (In + Z)
(n + Ga) is preferably set to 0.04 or less. That is, the In ₂ O ₃ -ZnO-based amorphous oxide film described in the description of the electromagnetic wave shielding material I of the present invention may contain only gallium (Ga) as an optional component. preferable. In this case, the specific resistance of the transparent conductive amorphous oxide film is approximately 3 × 10 ^{−4 to} 5 × 10 ⁻⁴ Ω · c.
m, it is possible to form a transparent conductive layer having a sheet resistance of 40 Ω / □ or less by setting the film thickness to about 1250 Å or more.

The indium (In) atomic ratio I
n / (In + Zn + Ga) is more preferably 0.6 to 0.9, particularly preferably 0.8 to 0.9. When the atomic ratio In / (In + Zn) of the indium is less than 0.5, the conductivity of the obtained film decreases, and when it exceeds 0.9, the resistance stability of the film decreases. The gallium (Ga) has an atomic ratio Ga / (In + Zn + Ga) of 0.1.
03 or less, more preferably 0.025 or less. If the gallium (Ga) atomic ratio Ga / (In + Zn + Ga) exceeds 0.04,
The conductivity of the resulting film decreases.

The electrical insulating layer alternately laminated on one surface of the transparent resin substrate with the transparent conductive layer made of the transparent conductive oxide film described above is a transparent electrical insulating material having a refractive index different from that of the transparent conductive layer. It is made of a substance. As the transparent electric insulating material which is a material of the electric insulating layer, a material having a lower refractive index (refractive index in a visible light region) than the above-mentioned transparent conductive oxide is preferable.
₂ , MgO, Al ₂ O _{3 and the} like. The thickness of the electric insulating layer is appropriately selected depending on the material so that the electromagnetic wave shielding material II having a reflectance of 20% or less in a visible light region is obtained.

In the electromagnetic wave shielding material II of the present invention, the transparent conductive layer and the above-mentioned electric insulating layer are alternately laminated on one surface of the transparent resin substrate so that the number of the above-mentioned transparent conductive layers becomes two or more. Have been. Here, “the number of layers of the transparent conductive layer is 2 or more” in the electromagnetic shielding material II of the present invention is the same as “the number of layers of the transparent conductive layer is 2 or more” in the electromagnetic shielding material I of the present invention described above. Meaning.

The number of layers of the transparent conductive layer and the electrical insulating layer is such that the number of transparent conductive layers is 2 or more, the reflectance in the visible light region is 20% or less, and the shielding effect against electromagnetic waves of 100 MHz or less is 40 dB or more. Electromagnetic shielding material II
Is appropriately selected according to each material and thickness so as to obtain finally. At this time, an antireflection layer for visible light may be formed if necessary, as in the case of the electromagnetic shielding material I of the present invention described above.

The reflectivity of the electromagnetic wave shielding material II of the present invention is preferably 15% or less, more preferably 10% or less. The average transmittance of visible light of the electromagnetic wave shielding material II of the present invention having such reflection characteristics is approximately 50% or more.

The shielding effect of the electromagnetic wave shielding material II of the present invention is preferably at least 45 dB, more preferably at least 50 dB. Here, “100 MHz” referred to in the electromagnetic wave shielding material II of the present invention.
The “electromagnetic wave below” has the same meaning as the “electromagnetic wave of 100 MHz or less” in the electromagnetic wave shielding material I of the present invention described above.

The above-mentioned electromagnetic wave shielding effect varies depending on the conductivity of the transparent conductive layer, the number of the transparent conductive layers, the material of the electric insulating layer, the thickness of the electric insulating layer, and the like. Therefore, if the transparent conductive layer and the electrical insulating layer described above are alternately laminated on the transparent resin base material such that the number of transparent conductive layers is two or more, the electromagnetic wave shielding effect described above must be 40 dB or more. It does not mean that shielding material can be obtained. Therefore,
The conductivity (material and thickness) of the transparent conductive layer, the number of the transparent conductive layers, the material of the electrical insulating layer, the thickness of the electrical insulating layer, and the like are set so that the above-described electromagnetic wave shielding effect has a desired value of 40 dB or more. Adjust appropriately.

The electromagnetic wave shielding material II of the present invention, like the above-mentioned electromagnetic wave shielding material I of the present invention, is used as an outermost layer on one or both sides thereof, and the electromagnetic wave shielding material is made of the above-mentioned visible light reflecting material. When having an anti-reflection layer, as a layer immediately inside thereof, or as a layer formed on the surface of the transparent resin substrate on the side opposite to the side on which the anti-reflection layer is provided, for television or the like May have a near-infrared cut layer for preventing malfunction of the remote controller.

The electromagnetic wave shielding material II of the present invention described above
Has a reflectance of 20% or less in a visible light region and a shielding effect of 40 dB or more on an electromagnetic wave of 100 MHz or less, like the electromagnetic wave shielding material I of the present invention described above.
Even when it is used as an electromagnetic wave shielding material for a display device, it is possible to shield electromagnetic waves radiated from the screen of the display device to a high degree while suppressing deterioration in image quality. The electromagnetic wave shield material II of the present invention can be used not only as an electromagnetic wave shield material for various display devices that emit electromagnetic waves, but also as an electromagnetic wave shield material for window glasses, pachinko machines (game tables), and the like.

The electromagnetic wave shielding material II of the present invention having such characteristics is obtained by alternately laminating a transparent conductive layer and an electric insulating layer on one surface of a transparent resin substrate, and then, if necessary, reflecting the visible light. It can be obtained by forming a prevention layer and / or a near infrared cut layer.

In this case, the transparent conductive layer is formed by forming the transparent conductive layer in the above-described electromagnetic wave shielding material I of the present invention by using an In ₂ O ₃ —ZnO-based non-magnetic material containing only gallium (Ga) as an optional constituent element. It can be carried out in the same manner as in the case of forming with a “crystalline oxide film”. The method for forming the electrical insulating layer can be appropriately selected according to the material and the like. However, if the electrical insulating layer is formed by the same method as the transparent conductive layer, the formation of the transparent conductive layer and the formation of the electrical insulating layer are the same. This is practically preferable because it becomes possible to carry out continuously by the above-mentioned apparatus.

[0072]

EXAMPLES Examples of the present invention will be described below with reference to comparative examples. However, in Examples 1 to 10 which will be described later, the electromagnetic wave shielding member I used for producing the electromagnetic wave shielding material I of the present invention will be described. The production method of the transparent conductive film is formed into a film forming example 1
As a film forming example 8, and a method of manufacturing a transparent conductive film for an electromagnetic wave shielding portion used to obtain the electromagnetic wave shielding materials of Comparative Examples 2 and 3 as film forming examples 9 to 10,
This will be described below in advance.

Film Forming Example 1 A biaxially oriented polyethylene terephthalate film (hereinafter abbreviated as “PET film”) having a thickness of 75 μm was used as a transparent resin substrate, and a hexagonal crystal represented by In ₂ O ₃ (ZnO) ₃ was used. An oxide sintered body composed of a layered compound and In ₂ O ₃ (as shown in Table 1, the indium atomic ratio In / (In
+ Zn) is 0.85. The relative density is 97%. ) Was used as a sputtering target to produce a transparent conductive film in the following manner.

First, the PET film and the sputtering target were set in a DC magnetron sputtering apparatus, and the inside of the vacuum chamber was evacuated at 120 ° C. until the pressure became 5 × 10 ⁻⁴ Pa or less. The vacuum was further applied for an hour. The pressure in the vacuum chamber after evacuation is 1 ×
It was 10 ^-4 Pa. Then, argon gas (purity 9)
A mixed gas (oxygen gas concentration = 3%) of oxygen gas (purity 99.99%) and oxygen gas (purity 99.99%) is introduced into a vacuum chamber, the pressure in the vacuum chamber is set to 1 × 10 ⁻¹ Pa, and DC output is performed. 2W / cm
^{2. A} film was formed at a substrate temperature of 20 ° C. to form a transparent conductive layer made of a predetermined transparent conductive oxide film on one side of the PET film. By forming this transparent conductive layer, an intended transparent conductive film was obtained.

The composition (atomic ratio of indium In / (In + Zn)) and crystallinity of the transparent conductive layer were determined by inductively coupled plasma emission spectroscopy (ICP; SPS-1500VR manufactured by Seiko Instruments Inc.) or X Line Diffraction (Rigaku Rotaflex RU-200B is used)
Was measured. Further, the thickness of the transparent conductive layer, the transmittance of light having a wavelength of 550 nm in the transparent conductive film, and the sheet resistance of the transparent conductive film (transparent conductive layer) are measured by a stylus method (the model used is DEKTAK303 manufactured by Sloan).
0), spectroscopy (U-321 manufactured by Hitachi, Ltd.)
0) or four-probe method (Loresta FP manufactured by Mitsubishi Yuka Co., Ltd.). Table 1 shows the results.

Film forming examples 2 to 5 The compositions shown in Table 1 (atomic ratio of indium In / (In + Z
n)) forming a transparent conductive layer made of a predetermined transparent conductive oxide film on one side of the PET film under the same conditions as in Film-forming Example 1 except that the oxide sintered body was used as a sputtering target, Thereby, the desired transparent conductive films were obtained. With respect to each of the transparent conductive layer and the transparent conductive film, the same items as those measured in Film-forming Example 1 were measured in the same manner as in Film-forming Example 1. These results are also shown in Table 1.

Film-forming example 6 A transparent conductive film comprising a predetermined transparent conductive oxide film on one side of a PET film under the same conditions as in film-forming example 1 except that the thickness of the transparent conductive layer was as shown in Table 1. A layer was formed, whereby a desired transparent conductive film was obtained. About the above-mentioned transparent conductive layer and transparent conductive film, film-forming example 1
Were measured in the same manner as in Film-forming Example 1. These results are also shown in Table 1.

Film- forming example 7 A transparent conductive layer was formed on one side of the PET film under the same conditions as in film-forming example 1, and a protective film (polypropylene protective film (thickness: 50 μm) was formed so as to cover this transparent conductive layer. ) Is laminated by a laminator,
A transparent conductive layer was formed on the other surface of the PET film under the same conditions as in Film Forming Example 1, and finally the protective film was peeled off to obtain a target transparent conductive film. With respect to the transparent conductive layer and the transparent conductive film, the same items as those measured in Film-forming Example 1 were measured in the same manner as in Film-forming Example 1. These results are also shown in Table 1.

Film- forming Example 8 The same conditions as in Film-forming Example 1 were used except that a near-infrared cut film (IRC film manufactured by Nippon Kayaku Co., Ltd.) was used as the transparent resin substrate instead of the PET film. A transparent conductive layer made of a predetermined transparent conductive oxide film was formed on one surface of the infrared cut film, whereby a target transparent conductive film was obtained. With respect to the transparent conductive layer and the transparent conductive film, the same items as those measured in Film-forming Example 1 were measured in the same manner as in Film-forming Example 1. These results are also shown in Table 1.

Film Forming Example 9 An ITO film (Sn: 5) having a thickness of 300 Å was formed on one side of the PET film under the same conditions as in Film Forming Example 5.
%), The sputtering target is changed to an Ag target, an Ag film having a thickness of 50 Å is formed on the ITO film, and an ITO film (Sn: 300 Å) having a thickness of 300 Å is formed on the Ag film. 5%) was formed under the same conditions as in Film-forming Example 5 to obtain a target transparent conductive film. With respect to the transparent conductive layer and the transparent conductive film, the same items as those measured in Film-forming Example 1 were measured in the same manner as in Film-forming Example 1. However, the crystallinity of the Ag film was not measured. These results are also shown in Table 1.

Film-forming Example 10 A transparent conductive layer made of an Au thin film was formed on one side of a PET film under the same conditions as in Film-forming Example 1 except that an Au target was used as a sputtering target. A conductive film was obtained. With respect to the transparent conductive layer and the transparent conductive film, the same items as those measured in Film-forming Example 1 were measured in the same manner as in Film-forming Example 1. However, the crystallinity of the Ag film was not measured. These results are also shown in Table 1.

[0082]

[Table 1]

Example 1 (Preparation of Electromagnetic Wave Shielding Material I) First, the transparent conductive film produced in Film Forming Example 1 was used as an upper layer electromagnetic wave shielding portion having a size of 15 cm in plan view.
X 15 cm cut out, and the size in plan view is 17 cm x 17 cm as an electromagnetic wave shield for the lower layer
Was cut out. Next, the lower layer electromagnetic wave shield part and the upper layer electromagnetic wave shield part were overlapped using an epoxy adhesive. At this time, the PET film of the upper electromagnetic wave shield portion is located on the transparent conductive layer of the lower electromagnetic wave shield portion via the epoxy resin layer,
In addition, the electromagnetic wave shields for the lower layer were superposed such that the center in plan view coincided with the center of the electromagnetic wave shield for the upper layer in plan view. Thereafter, the periphery of the superposed electromagnetic wave shield portion is covered with a double-sided conductive copper tape so that the transparent conductive layer of the lower electromagnetic wave shield portion and the transparent conductive layer of the upper electromagnetic wave shield portion can conduct. By bonding, the intended electromagnetic wave shielding material I was obtained.

With respect to the above-mentioned electromagnetic wave shielding material I, the transmittance and reflectance of light having a wavelength of 550 nm were measured using a spectrophotometer (model U-3210 manufactured by Hitachi, Ltd.). In addition, the shielding effect against an electromagnetic wave of 100 MHz was measured by the KEC method (Kansai Electronic Industry Promotion Center method). Table 2 shows the results.

Example 2 (Preparation of Electromagnetic Wave Shielding Material I) From the transparent conductive film produced in Film Forming Example 1 as an electromagnetic wave shielding portion for an upper layer, the size in plan view was 15 cm × 15.
cm, an electromagnetic shield part for a middle layer having a size of 17 cm × 17 cm in a plan view, and an electromagnetic shield part for a lower layer having a size of 19 c in a plan view.
Example 1 After cutting out each of mx 19 cm,
These electromagnetic wave shield portions are overlapped in the same manner as described above, and the periphery of the electromagnetic wave shield portion after the overlap is pasted together with a double-sided conductive copper tape in the same manner as in Example 1 to obtain the desired electromagnetic wave shield material. I was obtained. For the above-mentioned electromagnetic wave shielding material I, the items measured in Example 1 were measured in the same manner as in Example 1. Table 2 also shows these results.

Examples 3 to 7 (Electromagnetic wave shielding material I)
Preparation of) An intended electromagnetic wave shielding material I was obtained in the same manner as in Example 1 except that the transparent conductive films shown in Table 2 were used as materials for the electromagnetic wave shielding portion. With respect to each of the electromagnetic wave shielding materials I described above, the items measured in Example 1 were measured in the same manner as in Example 1. Table 2 also shows these results.

Example 8 (Preparation of Electromagnetic Wave Shielding Material I) A sheet having a size of 17 cm × 17 cm in plan view was cut out from the transparent conductive film manufactured in Film Forming Example 7 to form an electromagnetic wave shielding portion. A double-sided conductive copper tape was adhered to the periphery to obtain the target electromagnetic wave shielding material I. For the above-mentioned electromagnetic wave shielding material I, the items measured in Example 1 were measured in the same manner as in Example 1. Table 2 also shows these results.

Example 9 (Preparation of Electromagnetic Wave Shielding Material I) From the transparent conductive film produced in Film Forming Example 1, an electromagnetic wave shielding portion for an upper layer was 15 cm × 15 in a plan view.
cm in size and a size of 17 cm × 17 cm in plan view as an electromagnetic shielding portion for a lower layer was cut out from the transparent conductive film manufactured in Film Forming Example 7, and then the same as in Example 1. The electromagnetic wave shield portions were overlapped, and the periphery of the electromagnetic wave shield portion after the overlap was bonded together with a double-sided conductive copper tape in the same manner as in Example 1 to obtain an intended electromagnetic wave shield material I. For the above-mentioned electromagnetic wave shielding material I, the items measured in Example 1 were measured in the same manner as in Example 1. Table 2 also shows these results.

Example 10 (Preparation of Electromagnetic Wave Shielding Material I) From the transparent conductive film produced in Film Forming Example 1, an electromagnetic wave shielding portion for an upper layer was 15 cm × 15 in plan view.
cm and a size of 17 cm × 17 cm in plan view was cut out from the transparent conductive film produced in Film Forming Example 8 as an electromagnetic shielding portion for a lower layer. The electromagnetic wave shield portions were overlapped, and the periphery of the electromagnetic wave shield portion after the overlap was bonded together with a double-sided conductive copper tape in the same manner as in Example 1 to obtain an intended electromagnetic wave shield material I. For the above-mentioned electromagnetic wave shielding material I, the items measured in Example 1 were measured in the same manner as in Example 1. Table 2 also shows these results.

Comparative Example 1 A transparent conductive film manufactured in Film Forming Example 6 having a size of 17 cm × 17 cm in plan view was cut into an electromagnetic wave shielding portion, and a double-sided conductive copper tape was wrapped around the electromagnetic wave shielding portion. To obtain an electromagnetic wave shielding material. For the above-mentioned electromagnetic wave shielding material, the items measured in Example 1 were measured in the same manner as in Example 1. Table 2 also shows these results.

Comparative Examples 2 and 3 An electromagnetic wave shielding material was obtained in the same manner as in Example 1, except that the transparent conductive films shown in Table 2 were used as materials for the electromagnetic wave shielding portion. For each of the above electromagnetic wave shielding materials, the items measured in Example 1 were measured in the same manner as in Example 1. Table 2 also shows these results.

[0092]

[Table 2]

As shown in Table 2, Examples 1 to 1
0, each electromagnetic wave shielding material I has a wavelength of 550 nm.
Has a low reflectance of 5 to 7%, and a high shielding effect against electromagnetic waves of 100 MHz of 52 to 60 dB.
Further, the transmittance of light having a wavelength of 550 nm is as high as 56 to 74%. Therefore, it is presumed that even when these electromagnetic wave shielding materials I are used as electromagnetic wave shielding materials for display devices, electromagnetic waves radiated from the screen can be highly shielded while suppressing a decrease in image quality. You.

On the other hand, although the electromagnetic wave shielding material of Comparative Example 1 has a low reflectance of 6% for light having a wavelength of 550 nm,
Example 1 shows the shielding effect against 100 MHz electromagnetic wave.
~ Lower than each electromagnetic wave shielding material of Example 10. Also,
Each of the electromagnetic wave shielding materials of Comparative Examples 2 and 3 was 100 M
Hz shielding effect against electromagnetic wave of 56 dB or 5
Although it is as high as 7 dB, the reflectivity of light having a wavelength of 550 nm is higher than that of each of the electromagnetic shielding materials of Examples 1 to 10.

Example 11 (Production of Electromagnetic Wave Shielding Material II) A PET film having a thickness of 20
After forming a transparent conductive layer of 00 Å, the outer diameter in plan view is 17 cm × 17 cm and 15 cm × 15 cm.
A mask having an inner space of 500 cm is set on the film forming surface, and the power is switched to RF power, and a 500 angstrom thick SiO ₂ film is formed on the transparent conductive layer by the RF magnetron method using a SiO ₂ target. (Corresponding to an electric insulating film). Film forming conditions such as oxygen concentration at the time of forming the SiO ₂ film were the same as those in the film forming example 1. Thereafter, the mask was removed, and a transparent conductive layer having a thickness of 2000 Å was formed on the SiO ₂ film under the same conditions as in Film-forming Example 4 to obtain a desired electromagnetic wave shielding material II.

For the above-mentioned electromagnetic wave shielding material II, the transmittance and reflectance of light having a wavelength of 550 nm were measured in the same manner as in Example 1. The transmittance was 78% and the reflectance was 6%.
Met. The sheet resistance of the transparent conductive layer serving as the surface layer was 16Ω / □. Then, the shielding effect of this electromagnetic wave shielding material II on an electromagnetic wave of 100 MHz was measured in the same manner as in Example 1, and it was 55 dB. Thus, since the above-mentioned electromagnetic wave shielding material II has a low reflectance and a high electromagnetic wave shielding effect, when the electromagnetic wave shielding material II is used as an electromagnetic wave shielding material for a display device, it is radiated from the screen. It is presumed that it is possible to shield electromagnetic waves to a high degree while suppressing deterioration in image quality.

[0097]

As described above, the electromagnetic wave shielding material of the present invention has a low reflectance of 20% or less in the visible light region,
Shielding effect for the following electromagnetic waves 100MHz 40
Since the electromagnetic wave shielding material is as high as dB or more, when the electromagnetic wave shielding material is used as an electromagnetic wave shielding material for a display device, it is possible to shield electromagnetic waves radiated from a screen to a high degree while suppressing a decrease in image quality.

Claims (12)

[Claims] 1. An electromagnetic wave shield comprising a transparent resin substrate and a transparent conductive layer formed on one or both surfaces of the transparent resin substrate, wherein the number of the transparent conductive layers is two or more, An electromagnetic wave shielding material having a reflectivity in a region of not more than 20% and an electromagnetic wave shielding effect of not more than 100 MHz of not more than 40 dB. 2. The electromagnetic wave shielding material according to claim 1, wherein the transparent resin base material constituting the electromagnetic wave shielding portion has a near infrared cut function. 3. The electromagnetic wave shielding material according to claim 1, wherein the transparent conductive layer constituting the electromagnetic wave shielding portion is made of a transparent conductive oxide film having a sheet resistance of 40 Ω / □ or less. 4. The electromagnetic wave shielding material according to claim 3, wherein the transparent conductive oxide film is made of an amorphous oxide containing at least indium (In), zinc (Zn) and oxygen (O) as constituent elements. 5. An indium (In) atomic ratio In / (In + Zn) in a transparent conductive oxide film of 0.5 to 0.5.
The electromagnetic wave shielding material according to claim 3, wherein the number is 9. 6. The transparent conductive oxide film is made of indium (I
5. The method according to claim 3, wherein n), zinc (Zn), gallium (Ga) and oxygen (O) are constituent elements.
Electromagnetic wave shielding material according to 1. 7. The transparent conductive oxide film has an atomic ratio In / (In + Zn + Ga) of indium (In) of 0.5.
0.9, gallium (Ga) atomic ratio Ga / (In + Z)
The electromagnetic wave shielding material according to claim 6, wherein (n + Ga) is 0.04 or less. 8. The electromagnetic wave shielding material according to claim 1, wherein two or three electromagnetic wave shielding portions are overlapped. 9. The electromagnetic wave shielding material according to claim 8, wherein adjacent electromagnetic wave shielding portions are adhered to each other by an adhesive layer. 10. A near-infrared cut layer and / or an anti-reflection layer formed on one or both surfaces, and the near-infrared cut layer or the anti-reflection layer is an outermost layer in a thickness direction. The electromagnetic wave shielding material according to any one of claims 1 to 9. 11. A transparent conductive layer made of a transparent conductive oxide film containing indium (In), zinc (Zn), gallium (Ga), and oxygen (O) as constituent elements on one surface of a transparent resin substrate; The transparent conductive layer and the electrical insulating layers made of transparent electrical insulating materials having different refractive indexes are alternately laminated, and the number of the transparent conductive layers is 2 or more, and the reflectance in the visible light region is 20%. An electromagnetic wave shielding material characterized in that the shielding effect against electromagnetic waves of 100 MHz or less is 40 dB or more. 12. A transparent conductive oxide film comprising an amorphous oxide, wherein indium (I)
n) atomic ratio In / (In + Zn + Ga) is 0.5 to
0.9, gallium (Ga) atomic ratio Ga / (In + Zn)
The electromagnetic wave shielding material according to claim 11, wherein (+ Ga) is 0.04 or less.