Radio wave absorber film and method for producing same

Patent metadata

Field	Value
Publication number	US-2022288633-A1
Application number	US-202017635627-A
Country	US
Kind code	A1
Filing date	Jul 30, 2020
Priority date	Aug 19, 2019
Publication date	Sep 15, 2022
Grant date	—

Abstract

A radio wave absorber film which is thin and exhibits excellent radio wave absorption performance; and a method for producing this radio wave absorber film. The radio wave absorber film formed on a base material layer contains a magnetic body and a binder resin in a radio wave absorption layer; and an aromatic ester-urethane copolymer is used as the binder resin. The glass transition temperature of the binder resin is 100° C. or less, and 0° C. or less. The magnetic body is at least one of an ε-iron oxide, a barium ferrite magnetic body and a strontium ferrite magnetic body

First claim

1 . A radio wave absorber film comprising:
a substrate layer; and a radio wave absorbing layer formed on the substrate layer, the radio wave absorbing layer comprising a magnetic substance and a binder resin; and the binder resin comprising an aromatic ester-urethane copolymer.

2 . The radio wave absorber film according to claim 1 , wherein the binder resin has a glass transition temperature of 100° C. or less.

3 . The radio wave absorber film according to claim 2 , wherein the binder resin has a glass transition temperature of 0° C. or less.

4 . The radio wave absorber film according to claim 1 , wherein the magnetic substance comprises at least one selected from the group consisting of an epsilon-type iron oxide, barium ferrite magnetic substance, and strontium ferrite magnetic substance.

5 . The radio wave absorber film according to claim 1 , wherein the radio wave absorbing layer comprises a carbon nanotube.

6 . The radio wave absorber film according to claim 1 , wherein the film has a thickness of 200 μm or less.

7 . The radio wave absorber film according to claim 6 , wherein the radio wave absorbing layer has a thickness of 50 μm or less.

8 . A method for producing a radio wave absorber film comprising:
forming a radio wave absorbing layer by coating a substrate layer with paste comprising a magnetic substance and a binder resin to thereby form a coating film and then drying the coating film, the binder resin comprising an aromatic ester-urethane copolymer.

9 . The method for producing a radio wave absorber film according to claim 8 , wherein the method comprises cutting a laminate that is obtained by forming the radio wave absorbing layer and that comprises the substrate layer and the radio wave absorbing layer to thereby obtain a radio wave absorber film having a predetermined size.

Assignees

• Univ Tokyo
• Tokyo Ohka Kogyo Co Ltd

Inventors

• Ohkoshi Shin-Ichi
• Namai Asuka
• YOSHIKIYO Marie
• Hara Masayuki
• Asai Takahiro

Classifications

• H01F3/02

  made from sheets · CPC title

• H01F1/117 Primary

  Flexible bodies · CPC title

• H01Q17/002

  using short elongated elements as dissipative material, e.g. metallic threads or flake-like particles · CPC title

• H01Q17/00 Primary

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

• H05K9/0081

  Electromagnetic shielding materials, e.g. EMI, RFI shielding (H05K9/0003 takes precedence) · CPC title