Radio wave absorber, radio wave absorption structure including radio wave absorber, and composition for radio wave absorber
A radio wave absorber comprising a resin and a carbon fiber, wherein 60 to 90% by volume of the total carbon fiber 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.
1 . A radio wave absorber, comprising:
a resin; and
a carbon fiber selected from a pitch-based carbon fiber and a PAN-based carbon fiber,
wherein 60 to 90% by volume of the total carbon fiber 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 content of the carbon fiber is 2% by volume or less of the total volume of the radio wave absorber.
3 . 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.
4 . The radio wave absorber according to claim 1 , wherein the carbon fiber has a mean length within a range of 100 to 4000 μm.
5 . 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.
6 . The radio wave absorber according to claim 1 , further comprising:
a carbon 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 1 , which absorbs radio wave over the entire frequency range of 75 GHz to 105 GHz in an amount of 30% or more.
8 . A radio wave absorption structure, comprising:
the radio wave absorber of claim 1 , and
a radio wave reflector stacked on the surface side of the radio wave absorber in which the carbon fiber is lopsidedly distributed,
wherein the radio wave absorber has a thickness of 200 to 500 μm.
9 . The radio wave absorption structure according to claim 8 , which absorbs radio wave over the entire frequency range of 75 GHz to 105 GHz in an amount of 30% or more.
10 . The radio wave absorber according to claim 2 , further comprising:
a hollow particle in an amount of 10% by volume or less of the total volume of the radio wave absorber.
11 . The radio wave absorber according to claim 2 , wherein the carbon fiber has a mean length within a range of 100 to 4000 μm.
12 . The radio wave absorber according to claim 2 , 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.
13 . The radio wave absorber according to claim 2 , further comprising:
a carbon particle in an amount of 10% by volume or less of the total volume of the radio wave absorber.
14 . The radio wave absorber according to claim 2 , which absorbs radio wave over the entire frequency range of 75 GHz to 105 GHz in an amount of 30% or more.
15 . The radio wave absorber according to claim 3 , wherein the carbon fiber has a mean length within a range of 100 to 4000 μm.
16 . The radio wave absorber according to claim 3 , 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.
17 . The radio wave absorber according to claim 3 , further comprising:
a carbon particle in an amount of 10% by volume or less of the total volume of the radio wave absorber.
18 . The radio wave absorber according to claim 3 , which absorbs radio wave over the entire frequency range of 75 GHz to 105 GHz in an amount of 30% or more.
19 . The radio wave absorber according to claim 4 , 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.