Radio wave absorber, radio wave absorption structure including radio wave absorber, and composition for radio wave absorber

Patent metadata

Field	Value
Publication number	US-2025070475-A1
Application number	US-202418944263-A
Country	US
Kind code	A1
Filing date	Nov 12, 2024
Priority date	May 12, 2022
Publication date	Feb 27, 2025
Grant date	—

Abstract

A radio wave absorber comprising a resin and a carbon filler, wherein 60 to 90% by volume of the total carbon filler is present in a region from the first surface of the radio wave absorber to half of the total thickness of the radio wave absorber.

First claim

1 . A radio wave absorber comprising a resin and a carbon filler,
wherein 60 to 90% by volume of the total carbon filler is present in a region from the first surface of the radio wave absorber to half of the total thickness of the radio wave absorber.

2 . The radio wave absorber according to claim 1 , wherein the carbon filler comprises at least one of a carbon fiber and a carbon particle.

3 . The radio wave absorber according to claim 1 , wherein the carbon filler is a carbon fiber.

4 . The radio wave absorber according to claim 1 , wherein the carbon filler is a carbon fiber and a carbon particle.

5 . The radio wave absorber according to claim 1 , wherein the content of the carbon filler is 2% by volume or less of the total volume of the radio wave absorber.

6 . The radio wave absorber according to claim 1 , further comprising a hollow particle in an amount of 10% by volume or less of the total volume of the radio wave absorber.

7 . The radio wave absorber according to claim 2 , wherein the carbon fiber has a mean length within a range of 100 to 4000 μm.

8 . The radio wave absorber according to claim 1 , wherein the resin has an organosiloxane structure represented by the following formula (1):

in the formula, R 1 and R 2 represent independently, a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms.

9 . The radio wave absorber according to claim 1 , which absorbs radio wave over the entire frequency range of 75 GHz to 105 GHz in an amount of 30% or more.

10 . A radio wave absorption structure comprising:
the radio wave absorber according to claim 1 , and a radio wave reflector stacked on the first surface of the radio wave absorber, wherein the radio wave absorber has a thickness of 200 to 500 μm.

11 . The radio wave absorption structure according to claim 10 , which absorbs radio wave over the entire frequency range of 75 GHz to 105 GHz in an amount of 30% or more.

12 . A composition for a radio wave absorber comprising a resin having an organosiloxane structure represented by the following formula (1), a carbon fiber, a hollow particle, and a carbon particle,
wherein a content of the carbon fiber in the solid content in the composition is 2% by volume or less, a content of the hollow particle in the solid content of the composition is 10% by volume or less, and a content of the carbon particle in a solid content in the composition is 10% by volume or less:

wherein in the formula, R 1 and R 2 represent independently, a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms.

Assignees

• Idemitsu Kosan Co

Inventors

• Kondo Hirofumi
• Kajikawa Kotaro

Classifications

• C08G77/20

  containing silicon bound to unsaturated aliphatic groups · CPC title

• H01Q17/008 Primary

  with a particular shape (H01Q17/007 takes precedence) · CPC title

• H05K9/00

  Screening of apparatus or components against electric or magnetic fields (devices for absorbing radiation from an antenna H01Q17/00) · CPC title

• H01Q17/00

  Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems · CPC title

• G01S7/03

  Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver · CPC title