Electromagnetic shielding material
Provided is an electromagnetic shielding material having improved electromagnetic shielding properties. The present invention relates to an electromagnetic shielding material having a structure in which at least two metal foils are laminated via at least one insulating layer, the electromagnetic shielding material comprising at least one metal oxide layer on at least one boundary surface over which each metal foil is in contact with the insulating layer, the metal oxide layer having a thickness of from 1 to 30 nm.
1. An electromagnetic shielding material having a structure in which at least two metal foils are laminated via at least one insulating layer, the electromagnetic shielding material comprising at least one metal oxide layer on at least one boundary surface over which each metal foil is in contact with the insulating layer, the metal oxide layer having a thickness of from 1 to 20 nm,
wherein the metal oxide layer comprises an oxide of only the metal(s) included in the metal foil(s) and oxygen.
2. The electromagnetic shielding material according to claim 1 , wherein at least one of the metal foils comprises an outer surface of the electromagnetic shielding material, the thickness of the metal oxide layer on the surface of the metal foil is from 1 to 30 nm.
3. The electromagnetic shielding material according to claim 1 , wherein each metal foil has a thickness of from 4 to 50 μm.
4. The electromagnetic shielding material according to claim 1 , wherein the metal foils have a total thickness of from 8 to 200 μm.
5. The electromagnetic shielding material according to claim 1 , wherein the insulating layer has relative dielectric constant of from 2.0 to 10.0 at 20° C.
6. The electromagnetic shielding material according to claim 1 , wherein each metal foil has conductivity of 1.0×10 6 S/m or more at 20° C.
7. The electromagnetic shielding material according to claim 1 , wherein the insulating layer has a thickness of from 6 to 500 μm.
8. The electromagnetic shielding material according to claim 1 , wherein the electromagnetic shielding material has a total thickness of from 14 to 1000 μm.
9. A covering material or a cladding material for electric or electronic devices, comprising the electromagnetic shielding material according to claim 1 .
10. An electric or electronic device comprising the covering material or the cladding material according to claim 9 .
11. The electromagnetic shielding material according to claim 7 , wherein the thickness of the insulating layer is from 40 to 500 μm.
12. The electromagnetic shielding material according to claim 1 , wherein the thickness of the metal oxide layer over which each metal foil is in contact with the insulating layer is from 1 to 8 nm.
13. The electromagnetic shielding material according to claim 1 , wherein no chromium oxide is formed on the surface of the metal foil.