JP7256036B2 - Electromagnetic wave absorbing sheet and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electromagnetic wave absorbing sheet and a manufacturing method thereof.

As an electromagnetic wave absorbing sheet, a λ/4 type electromagnetic wave absorbing sheet using, for example, Sn-containing In ₂ O ₃ (ITO) as a resistive film is conventionally known. Further, in Patent Document 1, a λ/4 type electromagnetic wave absorption using a composite (PEDOT/PSS) of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) as a resistance film A sheet is disclosed.

WO2018/088492

However, when ITO is used for the resistive film, there are problems such as cracking of the resistive film when the λ/4 type electromagnetic wave absorber is bent. In addition, with the technique described in Patent Document 1, it is difficult to adjust the electromagnetic wave absorbability with high precision according to the desired electromagnetic wave frequency, and the reliability of the electromagnetic wave absorbability is also difficult to obtain.

An object of the present invention is to provide an electromagnetic wave absorbing sheet which has high electromagnetic wave absorbing power and which can be adjusted with high accuracy according to the frequency of the electromagnetic waves to be absorbed.

（式（III）中、Ｍは、水素原子、有機遊離基又は無機遊離基である。ｍ’は、Ｍの価数である。Ｒ^１３及びＲ^１４は、それぞれ独立に炭化水素基又は－（Ｒ^１５Ｏ）_ｒ－Ｒ^１６基である。Ｒ^１５は、それぞれ独立に炭化水素基又はシリレン基であり、Ｒ^１６は水素原子、炭化水素基又はＲ^１７ _３Ｓｉ－基であり、ｒは１以上の整数である。Ｒ^１７は、それぞれ独立に炭化水素基である。）
６．前記ドーパントがジ－２－エチルヘキシルスルホコハク酸ナトリウムである、前記４又は５に記載の電磁波吸収シート。
７．前記抵抗皮膜が、置換又は無置換のポリアニリンと、フェノール性水酸基を有する化合物とを含む、前記１～６のいずれかに記載の電磁波吸収シート。
８．λ／４型電磁波吸収体である、前記１～７のいずれかに記載の電磁波吸収シート。
９．前記１～８のいずれかに記載の電磁波吸収シートの製造方法であって、
前記置換又は無置換のポリアニリンを含む前記抵抗被膜を、置換又は無置換のポリアニリンとフェノール性水酸基を有する化合物とを含む組成物を用いた塗布法によって形成する工程を含む、電磁波吸収シートの製造方法。 According to the present invention, the following electromagnetic wave absorbing sheet and the like are provided.
1. Contains one or more electromagnetic wave absorbing layers and an electromagnetic wave shielding layer laminated in this order,
The electromagnetic wave absorbing layer includes a dielectric layer disposed on the side of the electromagnetic wave shielding layer, and a resistive film disposed on the opposite side of the dielectric layer to the electromagnetic wave shielding layer,
The resistive film in at least one of the one or more electromagnetic wave absorbing layers contains substituted or unsubstituted polyaniline,
Electromagnetic wave absorption sheet.
2. 1. The electromagnetic wave absorbing sheet according to 1 above, wherein the electromagnetic wave absorbing layer is one layer.
3. 1. The electromagnetic wave absorbing sheet according to 1 above, wherein the electromagnetic wave absorbing layer has two or more layers.
4. 4. The electromagnetic wave absorbing sheet according to any one of 1 to 3 above, wherein the substituted or unsubstituted polyaniline is a polyaniline composite doped with a dopant.
5. 5. The electromagnetic wave absorbing sheet according to 4 above, wherein the dopant is an organic acid ion generated from a sulfosuccinic acid derivative represented by the following formula (III).

(In formula (III), M is a hydrogen atom, an organic free radical or an inorganic free radical. m' is the valence of M. R ¹³ and R ¹⁴ are each independently a hydrocarbon group or -( R ¹⁵ O) _r —R ¹⁶ groups, where each R ¹⁵ is independently a hydrocarbon group or a silylene group, R ¹⁶ is a hydrogen atom, a hydrocarbon group or a R ¹⁷ ₃ Si— group, and r is 1; is an integer equal to or greater than R ¹⁷ and each R 17 is independently a hydrocarbon group.)
6. 6. The electromagnetic wave absorbing sheet as described in 4 or 5 above, wherein the dopant is sodium di-2-ethylhexylsulfosuccinate.
7. 7. The electromagnetic wave absorbing sheet according to any one of 1 to 6 above, wherein the resistive film contains substituted or unsubstituted polyaniline and a compound having a phenolic hydroxyl group.
8. 8. The electromagnetic wave absorbing sheet according to any one of 1 to 7 above, which is a λ/4 type electromagnetic wave absorber.
9. 9. The method for producing an electromagnetic wave absorbing sheet according to any one of 1 to 8 above,
A method for producing an electromagnetic wave absorbing sheet, comprising the step of forming the resistance coating containing the substituted or unsubstituted polyaniline by a coating method using a composition containing the substituted or unsubstituted polyaniline and a compound having a phenolic hydroxyl group. .

According to the present invention, it is possible to provide an electromagnetic wave absorbing sheet that has a high electromagnetic wave absorbing power and can adjust the electromagnetic wave absorbing power with high accuracy according to the frequency of the electromagnetic waves to be absorbed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the layer structure of the electromagnetic wave absorption sheet which concerns on 1st Embodiment of this invention. It is a figure explaining layer structure of the electromagnetic wave absorption sheet which concerns on 2nd Embodiment of this invention. It is a figure explaining the equivalent circuit of the electromagnetic wave absorption sheet which concerns on 2nd Embodiment of this invention. It is a figure explaining layer structure of the electromagnetic wave absorption sheet which concerns on 3rd Embodiment of this invention. It is a figure explaining the equivalent circuit of the electromagnetic wave absorption sheet which concerns on 3rd Embodiment of this invention. 4 is a diagram showing absorption characteristics of the electromagnetic wave absorbing sheet according to Example 1. FIG. FIG. 4 is a diagram showing absorption characteristics of the electromagnetic wave absorbing sheet according to Example 2. FIG. 10 is a diagram showing the absorption characteristics of the electromagnetic wave absorbing sheet according to Example 3; FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 4; FIG. 10 is a diagram showing the absorption characteristics of the electromagnetic wave absorbing sheet according to Example 5. FIG. 10 is a diagram showing the absorption characteristics of the electromagnetic wave absorbing sheet according to Example 6. FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 7; FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 8; FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 10; FIG. 11 shows the absorption characteristics of the electromagnetic wave absorbing sheet according to Example 11. FIG. 11 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 12; FIG. 13 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 13; FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 14; FIG. 11 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 15; FIG. 16 shows the absorption characteristics of the electromagnetic wave absorbing sheet according to Example 16. FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 17; FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 18; FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 19. FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 20; FIG. 11 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 21; FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 22; FIG. 10 is a diagram showing absorption characteristics of an electromagnetic wave absorbing sheet according to Example 23. FIG. 11 shows absorption characteristics of the electromagnetic wave absorbing sheet according to Example 24.

An electromagnetic wave absorbing sheet according to one embodiment of the present invention will be described below. In this specification, "x to y" represents a numerical range of "x or more and y or less". Also, the rules that are considered preferable can be arbitrarily adopted. That is, one preferred rule may be employed in combination with one or more other preferred rules. It can be said that a combination of preferable ones is more preferable.

[Electromagnetic wave absorption sheet]
An electromagnetic wave absorbing sheet according to one embodiment of the present invention includes one or more electromagnetic wave absorbing layers and an electromagnetic wave shielding layer laminated in this order. The electromagnetic wave absorbing layer includes a dielectric layer disposed on the side of the electromagnetic wave shielding layer, and a resistive film disposed on the side of the dielectric layer opposite to the electromagnetic wave shielding layer, and in at least one of the one or more electromagnetic wave absorbing layers contains substituted or unsubstituted polyaniline.
According to such an electromagnetic wave absorbing sheet, the electromagnetic wave absorbing ability can be adjusted with high precision according to the frequency of the desired electromagnetic wave, and the effect of excellent reliability of the electromagnetic wave absorbing ability can be obtained.

[First embodiment]
FIG. 1 is a diagram for explaining the layer structure of the electromagnetic wave absorbing sheet according to the first embodiment of the present invention. In FIG. 1, 11 is a resistive film, 21 is a dielectric layer, and 3 is an electromagnetic shielding layer. A1 is an electromagnetic wave absorbing layer including a resistive film 11 and a dielectric layer 21. FIG.

As shown in FIG. 1, the electromagnetic wave absorbing sheet according to this embodiment includes an electromagnetic wave absorbing layer A1 and an electromagnetic wave shielding layer 3 laminated in this order.
The electromagnetic wave absorbing layer A1 includes a dielectric layer 21 arranged on the side of the electromagnetic wave shielding layer 3 and a resistive film 11 arranged on the side of the dielectric layer 21 opposite to the electromagnetic wave shielding layer 3 .

In this embodiment, the electromagnetic wave absorbing sheet is a λ/4 type electromagnetic wave absorber. An incident wave, which is an electromagnetic wave, passes through the resistive film 11 and the dielectric layer 21 and is reflected by the electromagnetic wave shielding layer 3 to become a reflected wave. Assuming that the wavelength of the electromagnetic wave is λ, if the thickness _d1 of the dielectric layer 21 is λ/4, the resistive film 11 placed at the resonance point can absorb the electric field component of the electromagnetic wave. Here, the dielectric layer 21 has been described on the assumption that the dielectric _constant ε= ₁ . /(4(ε _r ) ^1/2 ).

(resistive film)
In this embodiment, the resistive coating 11 comprises substituted or unsubstituted polyaniline. Substituted or unsubstituted polyaniline can be included in resistive coating 11 as a substituted or unsubstituted polyaniline doped with a dopant, ie, a polyaniline composite. Substituted or unsubstituted polyaniline and polyaniline complexes are described in detail later.

Resistive films containing substituted or unsubstituted polyaniline can be finely and precisely adjusted in terms of surface resistance by, for example, adding a compound having a phenolic hydroxyl group, which will be described later. It can be adjusted with high precision. Further, since substituted or unsubstituted polyaniline and polyaniline composites are excellent in solubility in organic solvents, the resistive film 11 can be uniformly formed by a coating method using an organic solvent-based coating liquid (composition). As a result, the uniformity of surface resistance can also be improved, so that a high-performance electromagnetic wave absorbing sheet with no variation in electromagnetic wave absorbing ability can be realized. Furthermore, since the electromagnetic wave absorbing sheet using substituted or unsubstituted polyaniline as the resistive film has high flexibility, cracking can be prevented even when the sheet is bent.

Here, for comparison, a composite (PEDOT/PSS) of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) was used without using substituted or unsubstituted polyaniline for the resistance film. Consider when to use it. The electrical conductivity (surface resistance) of the film obtained from PEDOT/PSS can usually be adjusted by adding ethylene glycol or the like. It is difficult to adjust with high precision. In addition, PEDOT/PSS is usually used as a water-based coating liquid, but since water-based coating liquids tend to be inferior to organic solvent-based coating liquids in film forming properties, uniform surface resistance and, by extension, high-performance electromagnetic wave absorbing sheets can be achieved. It is difficult to A method of adding a surfactant to the water-based coating solution is also conceivable in order to obtain good film-forming properties, but the presence of the surfactant reduces the conductivity of the resistive film, or makes it unstable and prone to blurring. Therefore, it becomes more difficult to adjust the sheet resistance.

(binder)
The resistive film can contain a binder in addition to one or more selected from substituted or unsubstituted polyaniline and polyaniline composites.
As a binder, for example, one or more selected from the group consisting of acrylic, urethane, epoxy, styrene, polyamide, vinyl, polyvinyl acetal, polyester, polyester polyol, polyether polyol and polycarbonate. can include
The resistive film can also contain a binder obtained by curing a monomer, oligomer, or polymer having a reactive functional group such as acrylate or methacrylate at its end with ultraviolet rays, electron beams, or the like.

The resistive film can contain, in addition to one or more selected from substituted or unsubstituted polyaniline and polyaniline composites, a compound having a phenolic hydroxyl group, which will be described in detail later. A compound having a phenolic hydroxyl group can be contained in the resistive film derived from a coating solution (composition) used in a coating method which will be detailed later. In another embodiment, the compound having a phenolic hydroxyl group decreases as the coating liquid dries, and is only slightly contained in the resistive film or disappears from the resistive film.

(other ingredients)
The resistive film can contain other components other than polyaniline, polyaniline composites, binders, and compounds having phenolic hydroxyl groups, as long as they do not impair the effects of the present invention. Other components include, for example, additives such as inorganic materials, curing agents, plasticizers, and organic conductive materials.

Inorganic materials are added, for example, for the purpose of improving strength, surface hardness, dimensional stability and other mechanical properties, or improving electrical properties such as conductivity. Specific examples of inorganic materials include silica (silicon dioxide), titania (titanium dioxide), alumina (aluminum oxide), Sn-containing In ₂ O ₃ (ITO), Zn-containing In ₂ O ₃ and In ₂ O ₃ . Co-substituted compounds (oxides in which tetravalent and divalent elements are substituted with trivalent In), Sb-containing SnO ₂ (ATO), ZnO, Al-containing ZnO (AZO), Ga-containing ZnO (GZO), etc. .

Curing agents are added for the purpose of improving strength, surface hardness, dimensional stability and other mechanical properties. Specific examples of curing agents include thermosetting agents such as phenol resins, and photo-curing agents composed of acrylate-based monomers and photopolymerization initiators.

A plasticizer is added, for example, for the purpose of improving mechanical properties such as tensile strength and bending strength. Specific examples of plasticizers include phthalates and phosphates.

Organic conductive materials include carbon materials such as carbon black and carbon nanotubes.

In one embodiment, for example, 70 wt% or more, 80 wt% or more, 90 wt% or more, 98 wt% or more, 99 wt% or more, 99.5 wt% or more, 99.9 wt% or more, or 100% by mass is
one or more selected from substituted or unsubstituted polyaniline and polyaniline complexes,
one or more selected from substituted or unsubstituted polyaniline and polyaniline complexes and a binder;
One or more selected from substituted or unsubstituted polyaniline and polyaniline complex, a binder and a compound having a phenolic hydroxyl group, or one or more selected from substituted or unsubstituted polyaniline and polyaniline complex, a binder, and a phenolic hydroxyl group It may be one or more components arbitrarily selected from the compounds having and the other components described above.
The resin composition according to one aspect of the present invention is
one or more selected from essentially substituted or unsubstituted polyanilines and polyaniline complexes;
one or more selected from essentially substituted or unsubstituted polyanilines and polyaniline complexes and a binder;
One or more selected from substituted or unsubstituted polyaniline and polyaniline complex, a binder and a compound having a phenolic hydroxyl group, or one or more selected from substituted or unsubstituted polyaniline and polyaniline complex, a binder, and a phenolic hydroxyl group and one or more components arbitrarily selected from the above-described other components.
In this case, it may contain unavoidable impurities.

In this embodiment, the surface resistance of the resistive film 11 can be 280 Ω/□ or more, 300 Ω/□ or more, or 320 Ω/□ or more, and can be 460 Ω/□ or less, 440 Ω/□ or less, or 420 Ω/□. can be: In one embodiment, the sheet resistance of the resistive film 11 can be 377Ω/□.

The thickness of the resistance film 11 is not particularly limited, and can be, for example, 0.1 μm or more, 0.5 μm or more, or 1 μm or more, and can be 30 μm or less, 20 μm or less, or 10 μm or less.

(dielectric layer)
A dielectric can be used as the material of the dielectric layer 21 . The dielectric is not particularly limited, and examples thereof include polymer materials. More specifically, polycarbonate, polypropylene, polyethylene, polyimide, polyamide, polytetrafluoroethylene, polystyrene, polyethylene terephthalate, polyamide, polyvinylidene fluoride, polyester, Examples include polyphenylene sulfide and silicone rubber. Incidentally, the dielectric layer 21 may be a single layer body, or may be a layered body made of different materials.

In this embodiment, the thickness d ₁ of the dielectric layer 21 can be set to λ/(4(ε _r ) ^1/2 ) in accordance with the wavelength λ of the electromagnetic wave. Here, ε _r is the dielectric constant of the dielectric layer 2 . In one embodiment, the thickness _d1 of the dielectric layer 21 can be, for example, 0.01 mm or more, 0.05 mm or more, or 0.09 mm or more, and 10 mm or less, 7 mm or less, or 4 mm or less. can do.

(Electromagnetic wave shielding layer)
A conductive material can be used as the material of the electromagnetic wave shielding layer 3 . The conductive material is not particularly limited, and examples thereof include metals and metal oxides. The electromagnetic wave shielding layer 3 can be formed of, for example, metal foil such as copper foil, aluminum foil, gold foil, or the like. Further, the electromagnetic wave shielding layer 3 can also be formed of, for example, a deposited film of metal or the like.

The thickness of the electromagnetic wave shielding layer 3 is not particularly limited.

[Second embodiment]
FIG. 2 is a diagram for explaining the layer structure of the electromagnetic wave absorbing sheet according to the second embodiment of the present invention.

As shown in FIG. 2, the electromagnetic wave absorbing sheet according to the present embodiment has two electromagnetic wave absorbing layers (first electromagnetic wave absorbing layer A1 and second electromagnetic wave absorbing layer A2) and an electromagnetic wave shielding layer 3 laminated in this order. including
The first electromagnetic wave absorbing layer A1 comprises a first dielectric layer 21 arranged on the side of the electromagnetic shielding layer 3 and a first resistive film 11 arranged on the opposite side of the electromagnetic shielding layer 3 in the first dielectric layer 21. include.
The second electromagnetic wave absorbing layer A2 comprises a second dielectric layer 22 arranged on the side of the electromagnetic wave shielding layer 3 and a second resistive film 12 arranged on the opposite side of the electromagnetic wave shielding layer 3 in the second dielectric layer 22. include.

Also in this embodiment, the electromagnetic wave absorbing sheet is a λ/4 type electromagnetic wave absorber.
For the first resistive film 11 and the second resistive film 12, the description of the resistive film 11 regarding the first embodiment is appropriately used. As for the first dielectric layer 21 and the second dielectric layer 22, the description of the dielectric layer 21 regarding the first embodiment is used as appropriate. As for the electromagnetic wave shielding layer 3, the explanation regarding the first embodiment is also used as appropriate.
However, in the present embodiment, the surface resistance of each of the first resistive film 11 and the second resistive film 12 and the thickness of each of the first dielectric layer 21 and the second dielectric layer 22 are the same as in the first embodiment. can be different from These points will be explained below.

FIG. 3 is an equivalent circuit of the electromagnetic wave absorbing sheet according to the second embodiment.
3, _r1 is the surface resistance of the first resistive film 11, _d1 is the thickness of the first dielectric layer 21, _r2 is the surface resistance of the second resistive film 12, and _d2 is the surface resistance of the second dielectric layer 22. thickness.
Based on such an equivalent circuit (transmission line model), by performing theoretical calculations or electromagnetic field simulations, the sheet resistance of each of the first resistive film 11 and the second resistive film 12, the first dielectric layer 21 and the An optimal design is possible for each thickness of the two dielectric layers 22 .

In one embodiment, the sheet resistance r1 of the first resistive film 11 can be 500 Ω/□ or more, 700 Ω/□ or more, 900 Ω/□ or more, or 1000 Ω/□ or more, and can be 1100 Ω/□ or less, 1200 Ω/□ or more. /□ or less, 1500Ω/□ or less, or 2000Ω/□ or less. In one embodiment, the sheet resistance r1 of the first resistive film 11 can be 1060Ω/□.

In one embodiment, the surface resistance r2 of the second resistive film 12 can be 50Ω/□ or more, 100Ω/□ or more, 200Ω/□ or more, or 250Ω/□ or more, and can be 1000Ω/□ or less, 500Ω/□ or more. /□ or less, 400Ω/□ or less, or 300Ω/□ or less. In one embodiment, the surface resistance r2 of the second resistive film 12 can be 290Ω/□.

In one embodiment, the thickness _d1 of the first dielectric layer 21 can be 0.01 mm or more, 0.05 mm or more, or 0.09 mm or more, and can be 10 mm or less, 7 mm or less, or 4 mm or less. can do.

In one embodiment, the thickness _d2 of the second dielectric layer 22 can be 0.01 mm or more, 0.05 mm or more, or 0.09 mm or more, and can be 10 mm or less, 7 mm or less, or 4 mm or less. can do.

[Third Embodiment]
FIG. 4 is a diagram for explaining the layer structure of the electromagnetic wave absorbing sheet according to the third embodiment of the present invention.

As shown in FIG. 4, the electromagnetic wave absorbing sheet according to this embodiment includes three electromagnetic wave absorbing layers (first electromagnetic wave absorbing layer A1, second electromagnetic wave absorbing layer A2, and third electromagnetic wave absorbing layer A3) and an electromagnetic wave shielding layer. 3 are stacked in this order.
The first electromagnetic wave absorbing layer A1 comprises a first dielectric layer 21 arranged on the side of the electromagnetic shielding layer 3 and a first resistive film 11 arranged on the opposite side of the electromagnetic shielding layer 3 in the first dielectric layer 21. include.
The second electromagnetic wave absorbing layer A2 comprises a second dielectric layer 22 arranged on the side of the electromagnetic wave shielding layer 3 and a second resistive film 12 arranged on the opposite side of the electromagnetic wave shielding layer 3 in the second dielectric layer 22. include.
The third electromagnetic wave absorbing layer A3 comprises a third dielectric layer 23 arranged on the side of the electromagnetic wave shielding layer 3 and a third resistive film 13 arranged on the opposite side of the electromagnetic wave shielding layer 3 in the second dielectric layer 23. include.

Also in this embodiment, the electromagnetic wave absorbing sheet is a λ/4 type electromagnetic wave absorber.
As for the first resistive film 11, the second resistive film 12 and the third resistive film 13, the description of the resistive film 11 regarding the first embodiment is appropriately used. For the first dielectric layer 21, the second dielectric layer 22, and the third dielectric layer 23, the description of the dielectric layer 21 regarding the first embodiment is appropriately incorporated. As for the electromagnetic wave shielding layer 3, the explanation regarding the first embodiment is also used as appropriate.
However, in the present embodiment, the sheet resistance of each of the first resistive film 11, the second resistive film 12 and the third resistive film 13, the first dielectric layer 21, the second dielectric layer 22 and the third dielectric The thickness of each layer 23 may differ from the first embodiment. These points will be explained below.

FIG. 5 is an equivalent circuit of the electromagnetic wave absorbing sheet according to the third embodiment.
5, _r1 is the surface resistance of the first resistive film 11, _d1 is the thickness of the first dielectric layer 21, _r2 is the surface resistance of the second resistive film 12, and _d2 is the surface resistance of the second dielectric layer 22. thickness, r ₃ is the surface resistance of the third resistive film 13 , and d ₃ is the thickness of the third dielectric layer 23 .
Based on such an equivalent circuit (transmission line model), by performing theoretical calculations or electromagnetic field simulations, the sheet resistance of each of the first resistive film 11, the second resistive film 12, and the third resistive film 13, and the first An optimum design is possible for each thickness of the dielectric layer 21 , the second dielectric layer 22 and the third dielectric layer 23 .

In one embodiment, the sheet resistance _r1 of the first resistive film 11 can be 1000Ω/□ or more, 1200Ω/□ or more, 1400Ω/□ or more, or 1600Ω/□ or more, and can be 2500Ω/□ or less, It can be 2200Ω/□ or less, 2000Ω/□ or less, or 1800Ω/□ or less. In one embodiment, the surface resistance _r1 of the first resistive film 11 can be 1700Ω/□.

In one embodiment, the surface resistance _r2 of the second resistive film 12 can be 100 Ω/□ or more, 250 Ω/□ or more, 400 Ω/□ or more, or 500 Ω/□ or more, and can be 1100 Ω/□ or more, It can be 950 ohms/square or less, 800 ohms/square or less, or 700 ohms/square or less. In one embodiment, the sheet resistance _r2 of the second resistive film 12 can be 600Ω/□.

In one embodiment, the surface resistance _r3 of the third resistive film 13 can be 20Ω/□ or more, 50Ω/□ or more, 100Ω/□ or more, or 150Ω/□ or more, and 500Ω/□ or less, It can be 400Ω/□ or less, 300Ω/□ or less, or 250Ω/□ or less. In one embodiment, the surface resistance _r3 of the third resistive film 13 can be 200Ω/□.

In one embodiment, the thickness _d1 of the first dielectric layer 21 can be 0.01 mm or more, 0.05 mm or more, or 0.09 mm or more, and can be 10 mm or less, 7 mm or less, or 4 mm or less. can do.

In one embodiment, the thickness _d2 of the second dielectric layer 22 can be 0.01 mm or more, 0.05 mm or more, or 0.09 mm or more, and can be 10 mm or less, 7 mm or less, or 4 mm or less. can do.

In one embodiment, the thickness _d3 of the third dielectric layer 23 can be 0.01 mm or more, 0.05 mm or more, or 0.09 mm or more, and can be 10 mm or less, 7 mm or less, or 4 mm or less. can do.

[others]
(Layer structure)
In the above description, the electromagnetic wave absorbing layer including the resistive film and the dielectric layer is mainly laminated with one, two or three layers, but the present invention is not limited to this. For example, four or more electromagnetic wave absorbing layers may be laminated. Although the upper limit of the number of layers to be laminated is not particularly limited, it may be, for example, 10 layers or less, 8 layers or less, or 5 layers or less. Regardless of the number of layers, the electromagnetic wave absorbing sheet can be a λ/4 type electromagnetic wave absorber. can be set as appropriate.
By including two or more electromagnetic wave absorbing layers, the electromagnetic wave absorbing sheet can have a plurality of absorption peaks for electromagnetic wave frequencies. As a result, the electromagnetic wave absorbing ability can be exhibited over a wider range of frequency bands.

In each embodiment described above, another layer may be laminated on at least one of the incident side and the back side (electromagnetic wave shielding layer 3 side) of the electromagnetic wave absorbing sheet. Other layers are not particularly limited, and include, for example, a protective layer, an adhesive layer, and the like. When another layer is laminated on the incident side, the surface resistance of the resistive film and the thickness of the dielectric layer can be set in consideration of the dielectric constant and thickness of the other layer.

In the above description, the case where all the resistive films contained in the electromagnetic wave absorbing sheet contain substituted or unsubstituted polyaniline was mainly shown, but the present invention is not limited to this. At least one layer of resistive film contained in the electromagnetic wave absorbing sheet should contain substituted or unsubstituted polyaniline.

(Polyaniline)
The substituted or unsubstituted polyaniline contained in the resistive film will be described in detail below.
Substituted or unsubstituted polyaniline may be used alone (without forming a "polyaniline complex" described later), but as a polyaniline complex in which the substituted or unsubstituted polyaniline is doped with a dopant, resistance It is preferably contained in the coating.

The weight average molecular weight (hereinafter referred to as molecular weight) of polyaniline is preferably 20,000 or more. The molecular weight is preferably 20,000 to 500,000, more preferably 20,000 to 300,000, even more preferably 20,000 to 200,000. The weight average molecular weight is the molecular weight of the polyaniline, not the molecular weight of the polyaniline complex.

The molecular weight distribution is preferably 1.5 or more and 10.0 or less. From the viewpoint of electrical conductivity, a smaller molecular weight distribution is preferred, but from the viewpoint of solubility in a solvent, a wider molecular weight distribution may be preferred.
Molecular weight and molecular weight distribution are measured by gel permeation chromatography (GPC) in terms of polystyrene.

Substituents of the substituted polyaniline include, for example, linear or branched hydrocarbon groups such as methyl group, ethyl group, hexyl group and octyl group; alkoxy groups such as methoxy group and ethoxy group; aryloxy groups such as phenoxy group; Examples thereof include halogenated hydrocarbons such as fluoromethyl group ( _-CF3 group).
Polyaniline is preferably unsubstituted polyaniline from the viewpoint of versatility and economy.

Substituted or unsubstituted polyaniline is preferably polyaniline obtained by polymerization in the presence of a chlorine-free acid. Chlorine atom-free acids are, for example, acids consisting of atoms belonging to groups 1 to 16 and 18. A specific example is phosphoric acid. Polyaniline obtained by polymerization in the presence of phosphoric acid is exemplified as polyaniline obtained by polymerization in the presence of a chlorine-free acid.
Polyaniline obtained in the presence of chlorine-free acids can lead to lower chlorine content of polyaniline complexes.

The dopant for the polyaniline complex includes, for example, Bronsted acid ions generated from Bronsted acids or salts of Bronsted acids, preferably organic acid ions generated from organic acids or salts of organic acids, more preferably the following formula It is an organic acid ion generated from the compound represented by (I) (proton donor).
In the present invention, the dopant may be expressed as a specific acid, or the dopant may be expressed as a specific salt. shall be doped into a π-conjugated polymer with

M(XARn)m(I)
M in formula (I) is a hydrogen atom, an organic radical or an inorganic radical.
Organic free radicals include, for example, pyridinium groups, imidazolium groups, anilinium groups, and the like. Inorganic free radicals include, for example, lithium, sodium, potassium, cesium, ammonium, calcium, magnesium, iron, and the like.
X in formula (I) is an anionic group such as -SO ₃ ^- , -PO ₃ ^2- , -PO ₂ (OH) ^- , -OPO ₃ ^2- , -OPO ₂ (OH) ^- group, -COO ^- group, etc., preferably -SO ₃ ^- group.

A in formula (I) is a substituted or unsubstituted hydrocarbon group (having, for example, 1 to 20 carbon atoms).
The hydrocarbon group is a chain or cyclic saturated aliphatic hydrocarbon group, a chain or cyclic unsaturated aliphatic hydrocarbon group, or an aromatic hydrocarbon group.
The chain saturated aliphatic hydrocarbon group includes a linear or branched alkyl group (having 1 to 20 carbon atoms, for example). Cyclic saturated aliphatic hydrocarbon groups include cycloalkyl groups (having 3 to 20 carbon atoms, for example) such as cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl groups. The cyclic saturated aliphatic hydrocarbon group may be condensed with a plurality of cyclic saturated aliphatic hydrocarbon groups. For example, a norbornyl group, an adamantyl group, a condensed adamantyl group, and the like can be mentioned. Examples of chain unsaturated aliphatic hydrocarbons (having 2 to 20 carbon atoms, for example) include linear or branched alkenyl groups. Cyclic unsaturated aliphatic hydrocarbon groups (having, for example, 3 to 20 carbon atoms) include cyclic alkenyl groups. Aromatic hydrocarbon groups (having, for example, 6 to 20 carbon atoms) include phenyl, naphthyl and anthracenyl groups.

When A is a substituted hydrocarbon group, the substituents include an alkyl group (having 1 to 20 carbon atoms, for example), a cycloalkyl group (having 3 to 20 carbon atoms, for example), a vinyl group, an allyl group, an aryl group (having number is, for example, 6 to 20), alkoxy group (having, for example, 1 to 20 carbon atoms), halogen atom, hydroxyl group, amino group, imino group, nitro group, silyl group or ester bond-containing group.

R in formula (I) is bound to A and is -H, -R ¹ , -OR ¹ , -COR ¹ , -COOR ¹ , -(C=O)-(COR ¹ ), or -(C ═O)—(COOR ¹ ), where R ¹ is a hydrocarbon group which may contain a substituent, a silyl group, an alkylsilyl group, a —(R ² O)x—R ³ group, or — (OSiR ³ ₂ ) x—OR ³ groups. ^R2 is an alkylene group, ^R3 is a hydrocarbon group, and x is an integer of 1 or more. When x is 2 or more, multiple R ² may be the same or different, and multiple R ³ may be the same or different.

The hydrocarbon group for R ¹ (having, for example, 1 to 20 carbon atoms) includes a methyl group, ethyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group and pentadecyl group. , an eicosanyl group, and the like. The hydrocarbon group may be linear or branched.
Substituents of the hydrocarbon group include alkyl groups (having 1 to 20 carbon atoms, for example), cycloalkyl groups (having 3 to 20 carbon atoms, for example), vinyl groups, allyl groups, and aryl groups (having 6 to 20 carbon atoms, for example). , an alkoxy group (having, for example, 1 to 20 carbon atoms), a halogen group, a hydroxy group, an amino group, an imino group, a nitro group, or an ester bond-containing group. The hydrocarbon group of ^R3 is also the same as ^R1 .

The alkylene group (having 1 to 20 carbon atoms, for example) for R ² includes, for example, a methylene group, an ethylene group, a propylene group and the like.
n in formula (I) is an integer of 1 or more. When n is 2 or more, a plurality of R may be the same or different.
m in formula (I) is the valence of M/the valence of X.

式（ＩＩ）中、Ｍ及びＸは、式（Ｉ）と同様である。Ｘは、－ＳＯ_３ ^－基が好ましい。
Ｒ^４、Ｒ^５及びＲ^６は、それぞれ独立に水素原子、炭化水素基又はＲ^９ _３Ｓｉ－基である。３つのＲ^９はそれぞれ独立に炭化水素基である。
Ｒ^４、Ｒ^５及びＲ^６が炭化水素基である場合の炭化水素基としては、炭素数１～２４の直鎖もしくは分岐状のアルキル基、芳香環を含むアリール基（炭素数は例えば６～２０）、アルキルアリール基（炭素数は例えば７～２０）等が挙げられる。
Ｒ^９の炭化水素基としては、Ｒ^４、Ｒ^５及びＲ^６の場合と同様である。 As the compound represented by formula (I), dialkylbenzenesulfonic acid, dialkylnaphthalenesulfonic acid, or a compound containing two or more ester bonds is preferred.
The compound containing two or more ester bonds is more preferably a sulfophthalate ester or a compound represented by the following formula (II).

In formula (II), M and X are the same as in formula (I). X is preferably a —SO ₃ ^— group.
R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, a hydrocarbon group or _{an R 93} ^Si- group. Each of the three ^R9s is independently a hydrocarbon group.
Examples of hydrocarbon groups when R ⁴ , R ⁵ and R ⁶ are hydrocarbon groups include linear or branched alkyl groups having 1 to 24 carbon atoms, and aryl groups containing aromatic rings (having, for example, 6 to 20), alkylaryl groups (having, for example, 7 to 20 carbon atoms), and the like.
The hydrocarbon group for R ⁹ is the same as for R ⁴ , R ⁵ and R ⁶ .

R ⁷ and R ⁸ of formula (II) are each independently a hydrocarbon group or a —(R ¹⁰ O) _q —R ¹¹ group. R ¹⁰ is a hydrocarbon group or a silylene group, R ¹¹ is a hydrogen atom, a hydrocarbon group or R ¹² ₃ Si—, q is an integer of 1 or more. Each of the three R ¹² is independently a hydrocarbon group.

When R ⁷ and R ⁸ are hydrocarbon groups, the hydrocarbon group includes a linear or branched alkyl group having 1 to 24 carbon atoms, preferably 4 or more carbon atoms, an aryl group containing an aromatic ring (having are, for example, 6 to 20), alkylaryl groups (having a carbon number of, for example, 7 to 20), and the like. Specific examples include straight-chain or branched butyl, pentyl, hexyl, octyl group, decyl group, and the like.

The hydrocarbon group in R ⁷ and R ⁸ when R ¹⁰ is a hydrocarbon group includes, for example, a linear or branched alkylene group having 1 to 24 carbon atoms, an arylene group containing an aromatic ring (the number of carbon atoms is, for example, 6 to 20), an alkylarylene group (having, for example, 7 to 20 carbon atoms), or an arylalkylene group (having, for example, 7 to 20 carbon atoms). Further, in R ⁷ and R ⁸ , when R ¹¹ and R ¹² are hydrocarbon groups, the hydrocarbon group is the same as in R ⁴ , R ⁵ and R ⁶ , and q is 1 to 10. Preferably.

（式中、Ｘは式（Ｉ）と同様である。） Specific examples of the compound represented by formula (II) when R ⁷ and R ⁸ are —(R ¹⁰ O) _q —R ¹¹ groups are the two compounds represented by the following formulae.

(Wherein, X is the same as in formula (I).)

式（ＩＩＩ）中、Ｍは、式（Ｉ）と同様である。ｍ’は、Ｍの価数である。
Ｒ^１３及びＲ^１４は、それぞれ独立に、炭化水素基又は－（Ｒ^１５Ｏ）_ｒ－Ｒ^１６基である。Ｒ^１５は炭化水素基又はシリレン基であり、Ｒ^１６は水素原子、炭化水素基又はＲ^１７ _３Ｓｉ－基であり、ｒは１以上の整数である。３つのＲ^１７はそれぞれ独立に炭化水素基である。ｒが２以上の場合、複数のＲ^１５はそれぞれ同一でも異なってもよい。 More preferably, the compound represented by the above formula (II) is a sulfosuccinic acid derivative represented by the following formula (III).

In formula (III), M is the same as in formula (I). m' is the valence of M;
R ¹³ and R ¹⁴ are each independently a hydrocarbon group or a —(R ¹⁵ O) _r —R ¹⁶ group. R ¹⁵ is a hydrocarbon group or a silylene group, R ¹⁶ is a hydrogen atom, a hydrocarbon group or an R ¹⁷ ₃ Si— group, and r is an integer of 1 or more. Each of the three R ¹⁷ is independently a hydrocarbon group. When r is 2 or more, a plurality of R ¹⁵ may be the same or different.

When R ¹³ and R ¹⁴ are hydrocarbon groups, the hydrocarbon group is the same as R ⁷ and R ⁸ .
In R ¹³ and R ¹⁴ , when R ¹⁵ is a hydrocarbon group, the hydrocarbon group is the same as R ¹⁰ above. In R ¹³ and R ¹⁴ , when R ¹⁶ and R ¹⁷ are hydrocarbon groups, the hydrocarbon group is the same as R ⁴ , R ⁵ and R ⁶ above.
r is preferably 1-10.

Specific examples when R ¹³ and R ¹⁴ are —(R ¹⁵ O) _r —R ¹⁶ groups are the same as —(R ¹⁰ O) _q —R ¹¹ in R ⁷ and R ⁸ .
The hydrocarbon groups for R ¹³ and R ¹⁴ are the same as those for R ⁷ and R ⁸ , preferably butyl group, hexyl group, 2-ethylhexyl group and decyl group.

Di-2-ethylhexylsulfosuccinic acid and sodium di-2-ethylhexylsulfosuccinate (aerosol OT) are preferred as the compound represented by formula (I).

It can be confirmed by ultraviolet/visible/near-infrared spectroscopy or X-ray photoelectron spectroscopy that the dopant of the polyaniline complex is doped into the substituted or unsubstituted polyaniline, and the dopant adds a carrier to the polyaniline. As long as it has sufficient acidity to generate it, it can be used without particular restrictions on its chemical structure.

The doping ratio of the dopant to polyaniline is preferably 0.35 or more and 0.65 or less, more preferably 0.42 or more and 0.60 or less, still more preferably 0.43 or more and 0.57 or less, and particularly It is preferably 0.44 or more and 0.55 or less.
The doping rate is defined as (number of moles of dopant doped into polyaniline)/(number of moles of monomer units of polyaniline). For example, a doping rate of 0.5 for a polyaniline composite containing unsubstituted polyaniline and a dopant means that one dopant is doped with respect to two monomer unit molecules of polyaniline.

The doping rate can be calculated if the number of moles of the dopant and polyaniline monomer units in the polyaniline composite can be measured. For example, when the dopant is an organic sulfonic acid, the number of moles of sulfur atoms derived from the dopant and the number of moles of nitrogen atoms derived from the monomer unit of polyaniline are quantified by organic elemental analysis, and the ratio of these values is taken. Doping rate can be calculated. However, the method for calculating the doping rate is not limited to this means.

The polyaniline complex may or may not further contain phosphorus.
When the polyaniline composite contains phosphorus, the phosphorus content is, for example, 10 ppm by mass or more and 5000 ppm by mass or less.
The phosphorus content can be measured by ICP emission spectrometry.
Also, the polyaniline composite preferably does not contain Group 12 elements (such as zinc) as impurities.

A polyaniline composite can be manufactured by a well-known manufacturing method. For example, it can be produced by chemical oxidation polymerization of substituted or unsubstituted aniline in a solution containing a proton donor, phosphoric acid, and an emulsifier different from the proton donor and having two liquid phases. It can also be produced by adding an oxidative polymerization agent to a solution containing substituted or unsubstituted aniline, a proton donor, phosphoric acid, and an emulsifier different from the proton donor and having two liquid phases.

Here, "a solution having two liquid phases" means a state in which two incompatible liquid phases are present in the solution. For example, it means a state in which a "highly polar solvent phase" and a "lowly polar solvent phase" exist in a solution.
In addition, "a solution having two liquid phases" includes a state in which one liquid phase is a continuous phase and the other liquid phase is a dispersed phase. For example, the "high polarity solvent phase" is the continuous phase and the "low polarity solvent phase" is the dispersed phase, and the "low polarity solvent phase" is the continuous phase and the "high polarity solvent phase" is the dispersed phase. includes the state where
Water is preferable as the highly polar solvent used in the method for producing the polyaniline composite, and aromatic hydrocarbons such as toluene and xylene are preferable as the low polar solvent.

The proton donor is preferably a compound represented by formula (I) above.

The above emulsifier can be either an ionic emulsifier whose hydrophilic portion is ionic or a nonionic emulsifier whose hydrophilic portion is nonionic. may be used.

Oxidizing agents used in chemical oxidation polymerization include peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, and hydrogen peroxide; ammonium dichromate, ammonium perchlorate, potassium iron(III) sulfate, and iron trichloride. (III) Manganese dioxide, iodic acid, potassium permanganate, iron p-toluenesulfonate and the like can be used, preferably persulfates such as ammonium persulfate.
These may be used alone or in combination of two or more.

[Method for producing electromagnetic wave absorbing sheet]
The method for producing an electromagnetic wave absorbing sheet according to one embodiment of the present invention can be suitably used for producing the electromagnetic wave absorbing sheet according to the present invention described above.
A method for producing an electromagnetic wave absorbing sheet according to one embodiment of the present invention comprises a step of forming at least one layer of resistance film contained in the electromagnetic wave absorbing sheet by a coating method using a composition containing substituted or unsubstituted polyaniline. include.

[Composition]
In one embodiment, the composition comprises substituted or unsubstituted polyaniline. The composition can include substituted or unsubstituted polyaniline as a polyaniline conjugate as described above.

In one embodiment, the composition comprises
one or more selected from substituted or unsubstituted polyaniline and polyaniline complexes (hereinafter also referred to as "component (1)");
and a compound having a phenolic hydroxyl group (hereinafter also referred to as "component (2)").

(Compound having a phenolic hydroxyl group)
A compound having a phenolic hydroxyl group is a compound having one phenolic hydroxyl group, a compound having a plurality of phenolic hydroxyl groups, and a polymer compound composed of a repeating unit having one or more phenolic hydroxyl groups.

（式（Ａ）中、Ｒ^１０１は、炭素数１～２０のアルキル基、アルケニル基、シクロアルキル基、アリール基、アルキルアリール基又はアリールアルキル基である。
ｎ１は１～５の整数であり、好ましくは１～３であり、より好ましくは１である。ｎ１が２以上のとき、複数存在するＲ^１０１は、互いに同一でもよいし、異なってもよい。） Compounds having one phenolic hydroxyl group are preferably compounds represented by the following formulas (A), (B) and (C).

(In formula (A), R ¹⁰¹ is an alkyl group, alkenyl group, cycloalkyl group, aryl group, alkylaryl group or arylalkyl group having 1 to 20 carbon atoms.
n1 is an integer of 1-5, preferably 1-3, more preferably 1; When n1 is 2 or more, a plurality of R ¹⁰¹ may be the same or different. )

In the phenolic compound represented by formula (A), the substitution position of —OR ¹⁰¹ is preferably the meta-position or the para-position with respect to the phenolic hydroxyl group. By setting the substitution position of —OR ¹⁰¹ to the meta-position or para-position, the steric hindrance of the phenolic hydroxyl group is reduced, and the electrical conductivity of the composition can be further enhanced.

Specific examples of the phenolic compound represented by formula (A) include methoxyphenol (eg, 4-methoxyphenol), ethoxyphenol, propoxyphenol, isopropoxyphenol, butyloxyphenol, isobutyloxyphenol and tert-butyloxyphenol. mentioned.

（式（Ｂ）中、Ｒ^１０２は、炭素数１～２０のアルキル基、アルケニル基、アルキルチオ基、炭素数３～１０のシクロアルキル基、炭素数６～２０のアリール基、アルキルアリール基又はアリールアルキル基である。
ｎ２は０～７の整数であり、好ましくは０～３であり、より好ましくは１である。ｎ２が２以上のとき、複数存在するＲ^１０２は、互いに同一でもよいし、異なってもよい。）
式（Ｂ）で表わされるフェノール性化合物の具体例としては、ヒドロキシナフタレンが挙げられる。

(In formula (B), R ¹⁰² is an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an alkylthio group, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group or an aryl is an alkyl group.
n2 is an integer of 0-7, preferably 0-3, more preferably 1; When n2 is 2 or more, a plurality of R ¹⁰² may be the same or different. )
A specific example of the phenolic compound represented by formula (B) is hydroxynaphthalene.

（式（Ｃ）中、Ｒ^１０３は、炭素数１～２０のアルキル基、アルケニル基、アルキルチオ基、炭素数３～１０のシクロアルキル基、炭素数６～２０のアリール基、アルキルアリール基、アリールアルキル基、ハロゲン原子又はカルボキシ基である。
ｎ３は１～５の整数であり、好ましくは１～３であり、より好ましくは１である。ｎ３が２以上のとき、複数存在するＲ^１０３は、互いに同一でもよいし、異なってもよい。）

(In the formula (C), R ¹⁰³ is an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an alkylthio group, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group, an aryl It is an alkyl group, a halogen atom or a carboxy group.
n3 is an integer of 1-5, preferably 1-3, more preferably 1; When n3 is 2 or more, a plurality of R ¹⁰³ may be the same or different. )

Specific examples of compounds represented by formula (C) include o-, m- or p-cresol, o-, m- or p-ethylphenol, o-, m- or p-propylphenol (eg 4-isopropyl phenol), o-, m- or p-butylphenol, o-, m- or p-pentylphenol (e.g. 4-tert-pentylphenol), o-, m- or p-chlorophenol, salicylic acid, hydroxybenzoic acid is mentioned.

Examples of alkyl groups having 1 to 20 carbon atoms for R ¹⁰¹ to R ¹⁰³ in formulas (A), (B) and (C) include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and the like. .
Examples of the alkenyl group include groups having an unsaturated bond in the molecule of the alkyl group described above.
A cyclopentyl group, a cyclohexanyl group, etc. are mentioned as a cycloalkyl group.
Aryl groups include phenyl, naphthyl, and the like.
Examples of the alkylaryl group and the arylalkyl group include groups obtained by combining the alkyl group and the aryl group described above.

（式（Ｄ）中、Ｒ^１０４は炭化水素基、ヘテロ原子含有炭化水素基、ハロゲン原子、カルボキシ基、アミノ基、－ＳＨ基、スルホン酸基、又は水酸基である。
ｎ４は０～６の整数である。ｎ４が２以上のとき、複数存在するＲ^１０４は互いに同一でもよいし、異なってもよい。） Specific examples of compounds having multiple phenolic hydroxyl groups include catechol, resorcinol, and compounds represented by the following formula (D).

(In formula (D), R ¹⁰⁴ is a hydrocarbon group, a heteroatom-containing hydrocarbon group, a halogen atom, a carboxy group, an amino group, —SH group, a sulfonic acid group, or a hydroxyl group.
n4 is an integer of 0-6. When n4 is 2 or more, a plurality of R ¹⁰⁴ may be the same or different. )

The two phenolic hydroxyl groups of the compound having a phenolic hydroxyl group represented by formula (D) are preferably substituted at positions on the naphthalene ring that are not adjacent to each other.
Specific examples of the compound having a phenolic hydroxyl group represented by formula (D) include 1,6-naphthalenediol, 2,6-naphthalenediol and 2,7-naphthalenediol.

Specific examples of polymer compounds composed of repeating units having one or more phenolic hydroxyl groups include phenol resins, polyphenols, and poly(hydroxystyrene).

By changing the content of component (2) with respect to the content of component (1) in the composition, the surface resistance of the resistive film formed by the coating method using the composition can be suitably changed.
In one embodiment, by changing the content of component (2) in the range of 1 to 100 parts by mass with respect to 100 parts by mass of component (1) in the composition, the surface resistance of the resistive film is reduced to 1×10 ¹ Ω. /□ to 1×10 ⁶ . At this time, the surface resistance can be lowered by increasing the mass ratio of component (2) to component (1), and the surface resistance can be increased by decreasing the mass ratio of component (2) to component (1). can do.
In particular, in the sheet resistance band of about 100 Ω/□ to 1000 Ω/□, which is suitable for electromagnetic wave absorbing sheets, the change in sheet resistance is moderate when the mass ratio of component (2) to component (1) is changed. This property can be used to adjust the surface resistance of the resistive film with high accuracy.
Component (2) can improve the molecular orientation and the like of component (1) in the composition or at the time of forming a resistive film into a state suitable for exhibiting conductivity. Therefore, in one embodiment, even if component (2) disappears from the resistive film due to drying of the composition, etc., the effect is maintained. In other embodiments, the resistive coating comprises at least a portion of component (2) derived from the composition.

(Heat resistant stabilizer)
The composition may also contain a heat stabilizer. The heat-resistant stabilizer is an acidic substance or a salt of an acidic substance, and the acidic substance may be either an organic acid (acid of an organic compound) or an inorganic acid (acid of an inorganic compound).
The acidic substance that is a heat stabilizer is preferably an organic acid, more preferably an organic acid having one or more sulfonic acid groups, carboxyl groups, phosphoric acid groups, or phosphonic acid groups, and still more preferably sulfonic acid. It is an organic acid having one or more groups. Salts of acidic substances that are heat-resistant stabilizers include salts of these acidic substances.

The organic acid having one or more sulfonic acid groups is preferably a cyclic, chain or branched alkylsulfonic acid, substituted or unsubstituted aromatic sulfonic acid, or polysulfonic acid having one or more sulfonic acid groups.
Examples of the alkylsulfonic acid include methanesulfonic acid, ethanesulfonic acid, and di-2-ethylhexylsulfosuccinic acid. The alkyl group here is preferably a linear or branched alkyl group having 1 to 18 carbon atoms.
Examples of the aromatic sulfonic acid include sulfonic acid having a benzene ring, sulfonic acid having a naphthalene skeleton, sulfonic acid having an anthracene skeleton, substituted or unsubstituted benzenesulfonic acid, substituted or unsubstituted naphthalenesulfonic acid, and substituted or unsubstituted anthracenesulfonic acid, preferably substituted or unsubstituted naphthalenesulfonic acid. Specific examples include naphthalenesulfonic acid, dodecylbenzenesulfonic acid, and anthraquinonesulfonic acid.
Here, the substituent of the aromatic sulfonic acid is, for example, a group selected from the group consisting of an alkyl group, an alkoxy group, a hydroxy group, a nitro group, a carboxy group, and an acyl group, and may be substituted two or more times. .
The polysulfonic acid is a polymer compound in which a plurality of sulfonic acid groups are substituted on the main chain or side chains of the polymer chain. Examples include polystyrene sulfonic acid.

The organic acid having one or more carboxy groups is preferably a cyclic, chain or branched alkylcarboxylic acid, substituted or unsubstituted aromatic carboxylic acid, or polycarboxylic acid having one or more carboxy groups.
Examples of the alkylcarboxylic acid include undecylenic acid, cyclohexanecarboxylic acid, and 2-ethylhexanoic acid. Here, the alkyl group is preferably a linear or branched alkyl group having 1 to 18 carbon atoms.
Examples of the substituted or unsubstituted aromatic carboxylic acid include substituted or unsubstituted benzenecarboxylic acid and naphthalenecarboxylic acid. Here, the substituent is, for example, a group selected from the group consisting of a sulfonic acid group, an alkyl group, an alkoxy group, a nitro group, and an acyl group, and may be substituted two or more times. Specific examples include benzoic acid, naphthoic acid and trimesic acid.

The organic acid having one or more phosphoric acid groups or phosphonic acid groups is preferably a cyclic, linear or branched alkylphosphonic acid or alkylphosphonic acid having one or more phosphoric acid groups or phosphonic acid groups; substituted or unsubstituted aromatic aromatic or aromatic phosphonic acids; polyphosphoric or polyphosphonic acids.
Examples of the alkyl phosphate or alkyl phosphonic acid include dodecyl phosphate and bis(2-ethylhexyl) hydrogen phosphate. Here, the alkyl group is preferably a linear or branched alkyl group having 1 to 18 carbon atoms.
Examples of the aromatic phosphoric acid and aromatic phosphonic acid include substituted or unsubstituted benzenesulfonic acid or phosphonic acid, naphthalenesulfonic acid or phosphonic acid, and the like. Here, the substituent is, for example, a group selected from the group consisting of an alkyl group, an alkoxy group, a hydroxy group, a nitro group, a carboxy group, and an acyl group, and may be substituted two or more times. Examples include phenylphosphonic acid.

The composition according to one aspect of the present invention may contain two or more acidic substances and/or salts of acidic substances that are heat stabilizers. Specifically, it may contain a plurality of different acidic substances and/or salts of a plurality of different acidic substances.

In the composition according to one aspect of the present invention, the content of the heat stabilizer is preferably 0.01 to 10 parts by mass per 100 parts by mass of component (1).

(binder)
The composition can include the binders described for resistive coatings.

(other ingredients)
The composition can include other ingredients described for resistive coatings.

(solvent)
The composition can contain a solvent. The solvent may be an organic solvent or an inorganic solvent such as water, and may be a single solvent or a mixed solvent of two or more. Organic solvents are preferred. The organic solvent may be a water-soluble organic solvent or an organic solvent that is substantially immiscible with water (water-immiscible organic solvent).

The water-soluble organic solvent may be either a protic polar solvent or an aprotic polar solvent, such as alcohols such as isopropyl alcohol, 1-butanol, 2-butanol, 2-pentanol and benzyl alcohol; ketones such as acetone; ethers such as tetrahydrofuran and dioxane; and aprotic polar solvents such as N-methylpyrrolidone.

Examples of the water-immiscible organic solvent include hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and tetralin; halogen-containing solvents such as methylene chloride, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, and tetrachloroethane; and acetic acid. ester solvents such as ethyl, isobutyl acetate and n-butyl acetate; ketone solvents such as methyl isobutyl ketone, methyl ethyl ketone, cyclopentanone and cyclohexanone; ether solvents such as cyclopentyl methyl ether and 1-butoxy-2-propanol; mentioned. Among these, toluene, xylene, methyl isobutyl ketone (MIBK), chloroform, trichloroethane, and ethyl acetate are preferred because of their excellent solubility.

A water-soluble organic solvent and a water-immiscible organic solvent may be combined to form a mixed solvent of two or more. For example, a mixed solvent of toluene and isopropyl alcohol can be used.

(Coating method)
In one embodiment, the resistive coating is formed by applying the composition to the surface of the dielectric layer and drying the coating. In another embodiment, the composition is applied to the surface of any substrate, the coating is dried to form a resistive film, and then the resistive film on the substrate is bonded to the surface of the dielectric layer. You may After bonding, the substrate may be peeled from the resistive coating or may be used as a protective layer without peeling.

The method of applying the composition is not particularly limited, and known methods such as casting, spraying, dip coating, doctor blade, bar coating, spin coating, screen printing, and gravure printing can be used. can.

When drying the coating film, the coating film may be heated depending on the type of solvent. For example, it is heated at a temperature of 250° C. or less, preferably from 50 to 200° C., in an air current, and further heated under reduced pressure as necessary. The heating temperature and heating time are not particularly limited, and may be appropriately selected according to the material used.

[Use]
The use of the electromagnetic wave absorbing sheet described above is not particularly limited, and it can be widely used in various applications requiring electromagnetic wave absorption. Examples of applications include electromagnetic wave absorbers around millimeter wave radars mounted on automobiles and the like.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Example 1)
For an electromagnetic wave absorbing sheet having a layer structure similar to that shown in FIG. 1, the following structure was set and the absorption characteristics were determined. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Surface resistance r _{1 of the first resistive film 11} : 377Ω/□
Thickness d ₁ of first dielectric layer 21: 3.12 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0

In this Example 1 and Examples 2 to 8 described later, the surface resistance r ₁ of 377 Ω/□ can be obtained by forming the first resistive film (polyaniline layer) 11 according to [Setting Example 1 of Surface Resistance] below. can be set with good reproducibility.

[Setting example 1 of surface resistance]
(1) Production of polyaniline complex In a 1,000 mL separable flask, 32.4 g of Neocol SWC (sodium di-2-ethylhexyl sulfosuccinate: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 13.3 g of aniline and Sorbon T-20 (poly 0.9 g of a nonionic emulsifier having an oxyethylene sorbitan fatty acid ester structure: manufactured by Toho Chemical Industry Co., Ltd.) was added and dissolved in 320.4 g of toluene. 450 g of an 8.4% by weight phosphoric acid aqueous solution was added thereto, the reaction liquid having two liquid phases of toluene and water was stirred, and the internal temperature of the reaction liquid was cooled to 5°C. When the internal temperature of the reaction solution reached 5° C., a solution of 39.3 g of ammonium persulfate (APS) dissolved in 90.2 g of an 8.4% by weight phosphoric acid aqueous solution was added using a dropping funnel for 1 hour while stirring. dripped. After the dropwise addition was completed, the solution was further stirred for 8 hours while maintaining the internal temperature of the solution at 5°C (total reaction time: 9 hours).
After stopping the stirring, the content was transferred to a separatory funnel, and the aqueous layer and the toluene layer were separated by standing. After the separation, the organic layer was washed once with 180.3 g of a 1 M phosphoric acid aqueous solution and washed five times with 328.0 g of ion-exchanged water to obtain a polyaniline complex toluene solution.

The resulting solution was labeled as No. The insoluble matter was removed by filtration through filter paper No. 2 to obtain a toluene solution of the polyaniline complex. This solution was transferred to an evaporator, heated at 60° C., and depressurized to evaporate and distill off the volatile matter to obtain a polyaniline complex (protonated polyaniline).

(2) Production of coating polyaniline solution (resistive film-forming composition) 5 g of the polyaniline composite obtained above was dissolved in a mixed solvent of 92 g of toluene and 3 g of isopropyl alcohol.
Separately, 10 g of 2-naphthalenesulfonic acid hydrate and 290 g of 4-methoxyphenol were sequentially added to 200 g of 2-propanol to prepare a solution, and 0.45 g of the solution was added to 3.2 g of the above polyaniline complex solution. to obtain a composition.

(3) Coating of Polyaniline Layer The resulting composition (coating solution) was applied onto a film using a bar coater (“PI-1210R” manufactured by Tester Sangyo Co., Ltd.). At this time, the number of the bar rod of the bar coater was No. 100 was used. It was confirmed that a resistive film (polyaniline layer) having a surface resistance of 377 Ω/□ could be formed by drying at 110° C. for 15 minutes after coating.

（上式において、Γは反射係数、Ｚ_ｉｎは各層の金属板側を見込んだ入力インピーダンス、Ｚ_０は真空の波動インピーダンス、Ｚは各層の波動インピーダンス、γは伝搬定数、ｄは各層の膜厚である） [Theoretical calculation and simulation of absorption characteristics]
In this Example 1 and Examples 2 to 8 and 10 to 25 described later, the absorption characteristics were calculated theoretically from a transmission line model using the following theoretical formula, and electromagnetic field simulation software (“COMSOL Multiphysics” manufactured by COMSOL). ) was obtained by simulation using

(In the above equation, Γ is the reflection coefficient, _Zin is the input impedance of each layer looking into the metal plate side, _Z0 is the vacuum wave impedance, Z is the wave impedance of each layer, γ is the propagation constant, and d is the film thickness of each layer. is)

(Example 2)
Absorption characteristics were determined in the same manner as in Example 1, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Surface resistance r _{1 of the first resistive film 11} : 377Ω/□
Thickness d ₁ of first dielectric layer 21: 0.97 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0

(Example 3)
Absorption characteristics were determined in the same manner as in Example 1, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Surface resistance r _{1 of the first resistive film 11} : 377Ω/□
Thickness d ₁ of first dielectric layer 21: 2.10 mm
Relative permittivity ε _r1 of first dielectric layer 11: 2.2 (equivalent to polypropylene)
Relative permeability μr ₁ of first dielectric layer 11: 1.0

(Example 4)
Absorption characteristics were determined in the same manner as in Example 1, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Surface resistance r _{1 of the first resistive film 11} : 377Ω/□
Thickness d ₁ of first dielectric layer 21: 0.66 mm
Relative permittivity ε _r1 of first dielectric layer 11: 2.2 (equivalent to polypropylene)
Relative permeability μr ₁ of first dielectric layer 11: 1.0

(Example 5)
Absorption characteristics were determined in the same manner as in Example 1, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Surface resistance r _{1 of the first resistive film 11} : 377Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.80 mm
Relative permittivity ε _r1 of the first dielectric layer 11: 2.9 (corresponding to polyethylene terephthalate or polycarbonate)
Relative permeability μr ₁ of first dielectric layer 11: 1.0

(Example 6)
Absorption characteristics were determined in the same manner as in Example 1, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Surface resistance r _{1 of the first resistive film 11} : 377Ω/□
Thickness d ₁ of first dielectric layer 21: 0.57 mm
Relative permittivity ε _r1 of the first dielectric layer 11: 2.9 (corresponding to polyethylene terephthalate or polycarbonate)
Relative permeability μr ₁ of first dielectric layer 11: 1.0

(Example 7)
Absorption characteristics were determined in the same manner as in Example 1, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Surface resistance r _{1 of the first resistive film 11} : 377Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.67 mm
Relative permittivity ε _r1 of first dielectric layer 11: 3.5 (equivalent to polyimide)
Relative permeability μr ₁ of first dielectric layer 11: 1.0

(Example 8)
Absorption characteristics were determined in the same manner as in Example 1, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Surface resistance r _{1 of the first resistive film 11} : 377Ω/□
Thickness d ₁ of first dielectric layer 21: 0.52 mm
Relative permittivity ε _r1 of first dielectric layer 11: 2.9 (equivalent to polyimide)
Relative permeability μr ₁ of first dielectric layer 11: 1.0

(Example 9)
The theoretical calculation shown in Example 1 was performed on an electromagnetic wave absorbing sheet having a _layer structure similar to that shown in FIG. The surface resistance _r2 of the two-resistive film 12 was obtained.
As a result, it was confirmed that the maximum value of electromagnetic wave absorption was obtained under the following conditions for the electromagnetic wave absorbing sheet.
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Surface resistance r ₂ of the second resistive film 12: 290Ω/□

In Example 9 and Examples 10 to 24 described later, the sheet resistance _r1 of 1060 Ω/□ and the sheet resistance _r2 of 290 Ω/□ are determined by the following [setting example 2 of the sheet resistance]. By forming the resistive film (polyaniline layer) 11 and the second resistive film (polyaniline layer) 12, it is possible to set with good reproducibility.

[Setting example 2 of surface resistance]
(1) First Resistance Film 5 g of the polyaniline composite obtained in Example 1 was dissolved in a mixed solvent of 92 g of toluene and 3 g of isopropyl alcohol.
Separately, 10 g of 2-naphthalenesulfonic acid hydrate and 290 g of 4-methoxyphenol were sequentially added to 200 g of 2-propanol to prepare a solution, and 0.33 g of the solution was added to 3.2 g of the polyaniline complex solution. to obtain a composition.
The resulting composition was applied onto a film using a bar coater (“PI-1210R” manufactured by Tester Sangyo Co., Ltd.). At this time, the number of the bar rod of the bar coater was No. 100 was used. It was confirmed that a first resistive film (polyaniline layer) having a sheet resistance of 1060 Ω/□ could be formed by drying at 110° C. for 15 minutes after coating.

(2) Second resistance film 5 g of the polyaniline composite obtained in Example 1 was dissolved in a mixed solvent of 92 g of toluene and 3 g of isopropyl alcohol.
Separately, 10 g of 2-naphthalenesulfonic acid hydrate and 290 g of 4-methoxyphenol were sequentially added to 200 g of 2-propanol to prepare a solution, and 0.49 g of the solution was added to 3.2 g of the above polyaniline complex solution. to obtain a composition.
The resulting composition was applied onto a film using a bar coater (“PI-1210R” manufactured by Tester Sangyo Co., Ltd.). At this time, the number of the bar rod of the bar coater was No. 100 was used. It was confirmed that a second resistive film (polyaniline layer) having a surface resistance of 290 Ω/□ could be formed by drying at 110° C. for 15 minutes after coating.

(Example 10)
For an electromagnetic wave absorbing sheet having a layer structure similar to that shown in FIG. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.50 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.50 mm
Relative permittivity ε _r1 of second dielectric layer 12: 1.0
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 11)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.10 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.10 mm
Relative permittivity ε _r1 of second dielectric layer 12: 1.0
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 12)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.20 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.20 mm
Relative permittivity ε _r1 of second dielectric layer 12: 1.0
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 13)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.30 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.30 mm
Relative permittivity ε _r1 of second dielectric layer 12: 1.0
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 14)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.40 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.40 mm
Relative permittivity ε _r1 of second dielectric layer 12: 1.0
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 15)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.60 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.60 mm
Relative permittivity ε _r1 of second dielectric layer 12: 1.0
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 16)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d ₁ of first dielectric layer 21: 1.70 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.70 mm
Relative permittivity ε _r1 of second dielectric layer 12: 1.0
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 17)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.80 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.80 mm
Relative permittivity ε _r1 of second dielectric layer 12: 1.0
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 18)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.90 mm
Relative permittivity ε _r1 of first dielectric layer 11: 1.0
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.90 mm
Relative permittivity ε _r1 of second dielectric layer 12: 1.0
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 19)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.20 mm
Relative permittivity ε _r1 of first dielectric layer 11: 2.2 (equivalent to polypropylene)
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.20 mm
Relative permittivity ε _r1 of second dielectric layer 12: 2.2 (equivalent to polypropylene)
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 20)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d ₁ of first dielectric layer 21: 0.94 mm
Relative permittivity ε _r1 of first dielectric layer 11: 2.2 (equivalent to polypropylene)
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 0.94 mm
Relative permittivity ε _r1 of second dielectric layer 12: 2.2 (equivalent to polypropylene)
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 21)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d 1 of first dielectric layer ₂₁ : 1.00 mm
Relative permittivity ε _r1 of the first dielectric layer 11: 2.9 (corresponding to polyethylene terephthalate or polycarbonate)
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 1.00 mm
Relative permittivity ε _r1 of the second dielectric layer 12: 2.9 (corresponding to polyethylene terephthalate or polycarbonate)
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 22)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d ₁ of first dielectric layer 21: 0.83 mm
Relative permittivity ε _r1 of the first dielectric layer 11: 2.9 (corresponding to polyethylene terephthalate or polycarbonate)
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 0.83 mm
Relative permittivity ε _r1 of the second dielectric layer 12: 2.9 (corresponding to polyethylene terephthalate or polycarbonate)
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 23)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d ₁ of first dielectric layer 21: 0.09 mm
Relative permittivity ε _r1 of first dielectric layer 11: 3.5 (equivalent to polyimide)
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 0.09 mm
Relative permittivity ε _r1 of second dielectric layer 12: 3.5 (equivalent to polyimide)
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 24)
In Example 10, the absorption characteristics were determined in the same manner as in Example 10, except that the electromagnetic wave absorbing sheet had the following configuration. The results are shown in FIG.
<Configuration of electromagnetic wave absorbing sheet>
Sheet resistance r _{1 of the first resistive film 11} : 1060Ω/□
Thickness d ₁ of first dielectric layer 21: 0.76 mm
Relative permittivity ε _r1 of first dielectric layer 11: 3.5 (equivalent to polyimide)
Relative permeability μr ₁ of first dielectric layer 11: 1.0
Surface resistance r ₁ of the second resistive film 12: 290Ω/□
Thickness d ₁ of second dielectric layer 22: 0.76 mm
Relative permittivity ε _r1 of second dielectric layer 12: 3.5 (equivalent to polyimide)
Relative permeability μr ₁ of second dielectric layer 12: 1.0

(Example 25)
Theoretical calculations shown in Example 1 were performed on an electromagnetic wave absorbing sheet having a layer _structure similar to that shown in FIG. The surface resistance _r2 of the second resistance film 12 and the surface resistance _r3 of the third resistance film 13 were obtained.
As a result, it was confirmed that the maximum value of electromagnetic wave absorption was obtained under the following conditions for the electromagnetic wave absorbing sheet.
Surface resistance r ₁ of the first resistive film 11: 1700Ω/□
Surface resistance r _{2 of the second resistive film 12} : 600Ω/□
Sheet resistance r _{3 of the third resistive film 13} : 200Ω/□

Here, the surface resistance _r1 of 1700 Ω/square, the surface resistance _r2 of 600 Ω/square, and the surface resistance _r3 of 200 Ω/square are obtained, for example, by the following [setting example 3 of surface resistance]. By forming a (polyaniline layer) 11, a second resistance film (polyaniline layer) 12, and a third resistance film (polyaniline layer) 13, it is possible to set with good reproducibility.

[Setting example 3 of surface resistance]
(1) First Resistance Film 5 g of the polyaniline composite obtained in Example 1 was dissolved in a mixed solvent of 92 g of toluene and 3 g of isopropyl alcohol.
Separately, 10 g of 2-naphthalenesulfonic acid hydrate and 290 g of 4-methoxyphenol were sequentially added to 200 g of 2-propanol to prepare a solution, and 0.24 g of the solution was added to 3.2 g of the above polyaniline complex solution. to obtain a composition.
The resulting composition was applied onto a film using a bar coater (“PI-1210R” manufactured by Tester Sangyo Co., Ltd.). At this time, the number of the bar rod of the bar coater was No. 100 was used. It was confirmed that a first resistive film (polyaniline layer) having a sheet resistance of 1700 Ω/□ could be formed by drying at 110° C. for 15 minutes after coating.

(2) Second resistance film 5 g of the polyaniline composite obtained in Example 1 was dissolved in a mixed solvent of 92 g of toluene and 3 g of isopropyl alcohol.
Separately, 10 g of 2-naphthalenesulfonic acid hydrate and 290 g of 4-methoxyphenol were sequentially added to 200 g of 2-propanol to prepare a solution, and 0.4 g of the solution was added to 3.2 g of the above polyaniline complex solution. to obtain a composition.
The resulting composition was applied onto a film using a bar coater (“PI-1210R” manufactured by Tester Sangyo Co., Ltd.). At this time, the number of the bar rod of the bar coater was No. 100 was used. It was confirmed that a second resistive film (polyaniline layer) having a surface resistance of 600 Ω/□ could be formed by drying at 110° C. for 15 minutes after coating.

(3) Third Resistance Film 5 g of the polyaniline composite obtained in Example 1 was dissolved in a mixed solvent of 92 g of toluene and 3 g of isopropyl alcohol.
Separately, 10 g of 2-naphthalenesulfonic acid hydrate and 290 g of 4-methoxyphenol were sequentially added to 200 g of 2-propanol to prepare a solution, and 0.6 g of the solution was added to 3.2 g of the above polyaniline complex solution. to obtain a composition.
The resulting composition was applied onto a film using a bar coater (“PI-1210R” manufactured by Tester Sangyo Co., Ltd.). At this time, the number of the bar rod of the bar coater was No. 100 was used. It was confirmed that a third resistive film (polyaniline layer) having a surface resistance of 200 Ω/□ could be formed by drying at 110° C. for 15 minutes after coating.

(evaluation)
From the results of Examples 1 to 25, it was found that the amount of absorption can be arbitrarily adjusted according to the desired wavelength of electromagnetic waves. In addition, it was found that the number of absorption peaks increased when the number of electromagnetic wave absorbing layers was two or more, and the electromagnetic wave absorbing ability could be exhibited over a wider range of wavelength bands. Since the resistive film contains polyaniline, the electromagnetic wave absorbing ability can be adjusted with high accuracy, and such an effect can be satisfactorily exhibited.

A1 (first) electromagnetic wave absorbing layer 11 (first) resistive film 21 (first) dielectric layer A2 second electromagnetic wave absorbing layer 12 second resistive film 22 second dielectric layer A3 third electromagnetic wave absorbing layer 13 third resistor Coating 23 Third dielectric layer 3 Electromagnetic wave shielding layer

Claims (9)

One or more electromagnetic wave absorbing layers and an electromagnetic wave shielding layer laminated in this order,
The electromagnetic wave absorbing layer includes a dielectric layer disposed on the side of the electromagnetic wave shielding layer, and a resistive film disposed on the opposite side of the dielectric layer to the electromagnetic wave shielding layer,
70 at least one selected from substituted or unsubstituted polyaniline and a polyaniline composite in which the substituted or unsubstituted polyaniline is doped with a dopant, in at least one of the electromagnetic wave absorbing layers; Including mass% or more ,
Electromagnetic wave absorption sheet. 2. The electromagnetic wave absorbing sheet according to claim 1, wherein the electromagnetic wave absorbing layer is one layer. 2. The electromagnetic wave absorbing sheet according to claim 1, wherein the electromagnetic wave absorbing layer has two or more layers. 4. The electromagnetic wave absorbing sheet according to any one of claims 1 to 3, wherein the resistive film in at least one of the one or more electromagnetic wave absorbing layers contains the polyaniline composite. 5. The electromagnetic wave absorbing sheet according to claim 4, wherein the dopant is an organic acid ion generated from a sulfosuccinic acid derivative represented by the following formula (III).

(In formula (III), M is a hydrogen atom, an organic free radical or an inorganic free radical. m' is the valence of M. R ¹³ and R ¹⁴ are each independently a hydrocarbon group or -( R ¹⁵ O) _r —R ¹⁶ groups, where each R ¹⁵ is independently a hydrocarbon group or a silylene group, R ¹⁶ is a hydrogen atom, a hydrocarbon group or a R ¹⁷ ₃ Si— group, and r is 1; is an integer equal to or greater than R ¹⁷ and each R 17 is independently a hydrocarbon group.) 6. The electromagnetic wave absorbing sheet according to claim 4, wherein the dopant is sodium di-2-ethylhexylsulfosuccinate. The electromagnetic wave absorbing sheet according to any one of claims 1 to 6, wherein said resistive film contains substituted or unsubstituted polyaniline and a compound having a phenolic hydroxyl group. The electromagnetic wave absorbing sheet according to any one of claims 1 to 7, which is a λ/4 type electromagnetic wave absorber. A method for producing an electromagnetic wave absorbing sheet according to any one of claims 1 to 8,
Manufacture of an electromagnetic wave absorbing sheet, comprising the step of forming the resistance film containing the substituted or unsubstituted polyaniline by a coating method using a composition containing the substituted or unsubstituted polyaniline and a compound having a phenolic hydroxyl group. Method.

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