Electromagnetic wave absorbing material

• US 6,214,454 B1
• Filed: 09/25/1997
• Issued: 04/10/2001
• Est. Priority Date: 09/25/1996
• Status: Expired due to Fees

• Current Assignee: Chioyoda Ute Co., Ltd., Nippon Paint Company Limited (Rainbow Light Limited)
• Original Assignee: Japan and Chiyoda UTE Company Limited, Nippon Paint Company Limited (Rainbow Light Limited)
• Inventors: Kanda, Kazunori, Morimoto, Masato, Takumi, Fujita, Junichi, Hada
• Primary Examiner(s): Cole, Elizabeth M.
• Application Number:
  US08/937,464
• Time in Patent Office: 1,293 Days
• Field of Search: 428/294.7, 428/323, 428/457
• US Class Current: 428/294.7
• CPC Class Codes: B32B 13/06 of metal
• CPC Class Codes: B32B 2311/12 Copper
• CPC Class Codes: B32B 2311/22 Nickel or cobalt
• CPC Class Codes: B32B 2311/24 Aluminium
• CPC Class Codes: B32B 2311/30 Iron, e.g. steel
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: C04B 14/28 of calcium
• CPC Class Codes: C04B 14/30 Oxides other than silica ferrites C04B14/363
• CPC Class Codes: C04B 14/34 Metals , e.g. ferro-silicon
• CPC Class Codes: C04B 14/386 Carbon carbon nanotubes C04B14/026
• CPC Class Codes: C04B 14/48 Metal
• CPC Class Codes: C04B 18/24 Vegetable refuse, e.g. rice husks, maize-ear refuse; Cellulosic materials, e.g. paper , cork
• CPC Class Codes: C04B 20/002 Hollow or porous granular materials
• CPC Class Codes: C04B 20/1062 Metals
• CPC Class Codes: C04B 2103/302 Water reducers
• CPC Class Codes: C04B 2103/40 Surface-active agents, dispersants
• CPC Class Codes: C04B 2111/00258 Electromagnetic wave absorbing or shielding materials
• CPC Class Codes: C04B 2111/00482 Coating or impregnation materials
• CPC Class Codes: C04B 2111/00612 as one or more layers of a layered structure
• CPC Class Codes: C04B 2111/28 Fire resistance, i.e. materials resistant to accidental fires or high temperatures
• CPC Class Codes: C04B 2111/40 : Porous or lightweight materials
• CPC Class Codes: C04B 24/26 : obtained by reactions only involving carbon-to-carbon unsaturated bonds C04B24/243 takes precedence
• CPC Class Codes: C04B 28/04 : Portland cements
• CPC Class Codes: C04B 28/14 : containing calcium sulfate cements gypsum-paper plates E04C
• CPC Class Codes: C04B 38/02 : by adding chemical blowing agents
• CPC Class Codes: C04B 38/10 : by using foaming agents C04B38/02 takes precedenceor by using mechanical means, e.g. adding preformed foam
• CPC Class Codes: C04B 41/51 : Metallising , e.g. infiltration of sintered ceramic preforms with molten metal covering materials with metals in general C23C; ceramic compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides, other than as macroscopic reinforcing agents C22C; infiltration of preforms containing free metal, e.g. cermets C22C
• CPC Class Codes: Y02W 30/91 : Use of waste materials as fillers for mortars or concrete
• CPC Class Codes: Y10T 428/249932 : Fiber embedded in a layer derived from a water-settable material [e.g., cement, gypsum, etc.]
• CPC Class Codes: Y10T 428/25 : Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/31678 : Of metal

Abstract

The present invention provides an electromagnetic wave absorbing material which comprises an electromagnetic wave absorbing layer comprising a hydraulic inorganic binder and a fibrous conductor.

The present invention also provides an electromagnetic wave absorbing material which comprises an electromagnetic wave absorbing layer comprising a hydraulic inorganic binder, a magnetic powder and a fibrous conductor.

Claims

1. An electromagnetic wave absorbing material which comprises an electromagnetic wave absorbing layer comprising a hydraulic inorganic binder (a) and 0.01 to 0.54 part by weight, per 100 parts by weight of said hydraulic inorganic binder (a), of a fibrous conductor (b), and further comprises an electromagnetic wave reflecting layer.

2. The electromagnetic wave absorbing material according to claim 1, wherein said hydraulic inorganic binder (a) comprises at least one member selected from the group consisting of cement, mortar, calcium silicate and gypsum and wherein said electromagnetic wave absorbing layer has a thickness of 5 to 50 mm.

3. The electromagnetic wave absorbing material according to claim 2, wherein said hydraulic inorganic binder (a) is gypsum and wherein said electromagnetic wave absorbing layer further comprises at least one additive (c) selected from the group consisting of an expandable filler (c-1), a fibrous additive (c-2), a foaming agent (c-3), a water reducing agent (c-4) and a surfactant (c-5) and the amount of said additive (c) being 0.01 to 20 parts by weight, per 100 parts by weight of the hydraulic inorganic binder (a), said layer having a thickness of 7 to 25 mm and a specific gravity of 0.50 to 0.90.

4. The electromagnetic wave absorbing material according to claim 3, wherein said additive (c) is at least one expandable filler (c-1) selected from among organic expandable fillers and inorganic expandable fillers.

5. The electromagnetic wave absorbing material according to claim 1, wherein said electromagnetic wave reflecting layer comprises at least one member selected from the group consisting of conductive substrates, metal vapor deposited film, metal foils and metal powders and has a shielding ability of not less than 20 dB.

6. An electromagnetic wave absorbing material which comprises an electromagnetic wave absorbing layer consisting essentially of a hydraulic inorganic binder (a) and 0.01 to 0.54 parts by weight, per 100 parts by weight of said hydraulic inorganic binder (a), of a fibrous conductor (b), and further comprises an electromagnetic wave reflecting layer.

7. An electromagnetic wave absorbing layer consisting essentially of a hydraulic inorganic binder (a) and 0.01 to 0.54 parts by weight, per 100 parts by weight of said hydraulic inorganic binder (a), of a fibrous conductor (b) and at least one additive (c) selected from the group consisting of an expandable filler (c-1), a fibrous additive (c-2), a foaming agent (c-3), a water reducing agent (c-4) and a surfactant (c-5) with the amount of (c) being 0.01 to 20 parts by weight per 100 parts by weight of the hydraulic inorganic binder (a).