US 12,308,523 B2
Radio wave absorbing composition and radio wave absorber
Yoshihiro Nakai, Minami-ashigara (JP); and Hirokazu Hashimoto, Minami-ashigara (JP)
Assigned to FUJIFILM Corporation, Tokyo (JP)
Filed by FUJIFILM Corporation, Tokyo (JP)
Filed on Feb. 8, 2022, as Appl. No. 17/666,984.
Application 17/666,984 is a continuation of application No. PCT/JP2020/029625, filed on Aug. 3, 2020.
Claims priority of application No. 2019-148186 (JP), filed on Aug. 9, 2019.
Prior Publication US 2022/0166147 A1, May 26, 2022
Int. Cl. H01Q 17/00 (2006.01); C01G 49/00 (2006.01); C08K 9/06 (2006.01); H05K 9/00 (2006.01); C08K 3/22 (2006.01); C08K 5/54 (2006.01); C08L 23/00 (2006.01); H01F 1/113 (2006.01); H01F 1/37 (2006.01)
CPC H01Q 17/004 (2013.01) [C01G 49/0036 (2013.01); C01G 49/009 (2013.01); C08K 9/06 (2013.01); H05K 9/0075 (2013.01); H05K 9/0083 (2013.01)] 8 Claims
 
1. A radio wave absorber,
which comprises a radio wave absorber layer comprising:
a magnetic powder; and
a binder,
wherein the magnetic powder is a powder of a substitution-type hexagonal ferrite subjected to surface treatment with a surface treatment agent,
the surface treatment agent is a silicon-based compound, and
the binder is an olefin-based resin, said olefin-based resin being one or more resins selected from the group consisting of polymethylpentene, a cycloolefin resin, and an olefin-based resin containing a maleic acid anhydride unit, and
which comprises the magnetic powder in an amount of 50% by mass or more and 75% by mass or less, with respect to the total mass (100% by mass) of the magnetic powder and the resin, and
which does not comprise a metal layer, the metal layer being a layer containing a metal and substantially reflecting radio waves, wherein “substantially reflecting radio waves” means reflecting 90% or more of incident radio waves in a case where the radio waves are incident on the radio wave absorber layer in a state where the metal layer is laminated on the back surface of the radio wave absorber layer.