KR-102964144-B1 - Radio wave absorber film, and method of manufacturing the same

KR102964144B1KR 102964144 B1KR102964144 B1KR 102964144B1KR-102964144-B1

Abstract

The present invention provides a radio wave absorber film having excellent radio wave absorption performance as a thin film, and a method for manufacturing said radio wave absorber film. In the radio wave absorber film formed on a substrate layer, a magnetic material and a binder resin are contained in the 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 preferably 100°C or lower, and more preferably 0°C or lower. The magnetic material is preferably at least one selected from the group consisting of epsilon-type iron oxide, a barium ferrite magnetic material, and a strontium ferrite magnetic material.

Inventors

오코시 신이치
나마이 아스카
요시키요 마리에
하라 마사유키
아사이 다카히로

Assignees

고쿠리츠다이가쿠호우진 도쿄다이가쿠
도오꾜오까고오교 가부시끼가이샤

Dates

Publication Date: 20260512
Application Date: 20200730
Priority Date: 20190819

Claims (9)

A radio wave absorber film having a radio wave absorbing layer formed on a substrate layer, The above-mentioned radio wave absorption layer comprises a magnetic material that magnetically resonates in a frequency band of 40 GHz or more and 300 GHz or less, a binder resin, and a dispersant, and The above dispersant is at least one selected from the group consisting of silane coupling agents, titanate coupling agents, zirconate coupling agents, and aluminate coupling agents, and The above binder resin comprises an aromatic ester-urethane copolymer, and A radio wave absorber film having a reflection attenuation amount measured from the side of the above-mentioned radio wave absorbing layer, having a peak with an absolute value of 30 dB or more in a frequency band of 40 GHz or more and 300 GHz or less.
In Article 1, A radio wave absorber film having a glass transition temperature of the binder resin of the above-mentioned amount of 100°C or less.
A radio wave absorber film having a radio wave absorbing layer formed on a substrate layer, The above-mentioned electromagnetic wave absorption layer comprises a magnetic material, a binder resin, and a dispersant, and The above dispersant is at least one selected from the group consisting of silane coupling agents, titanate coupling agents, zirconate coupling agents, and aluminate coupling agents, and The above binder resin comprises an aromatic ester-urethane copolymer, and The glass transition temperature of the above binder resin is 0 ℃ or lower, and A radio wave absorber film having a thickness of the above-mentioned radio wave absorbing layer of 10 μm or more and 50 μm or less.
In any one of paragraphs 1 to 3, A radio wave absorber film comprising at least one magnetic material selected from the group consisting of epsilon-type iron oxide, barium ferrite magnetic material, and strontium ferrite magnetic material.
In any one of paragraphs 1 to 3, A radio wave absorber film in which the above-mentioned radio wave absorbing layer comprises carbon nanotubes.
In Article 1, A radio wave absorber film having a thickness of 200 μm or less.
In Article 6, A radio wave absorber film having a thickness of 50 μm or less of the above-mentioned radio wave absorbing layer.
A process for forming a radio wave absorption layer, comprising applying a paste containing a magnetic material, a binder resin, and a dispersant onto a substrate layer to form a coating film, and then drying the coating film to form a radio wave absorption layer. The above dispersant is at least one selected from the group consisting of silane coupling agents, titanate coupling agents, zirconate coupling agents, and aluminate coupling agents, and The above binder resin comprises an aromatic ester-urethane copolymer, and The glass transition temperature of the above binder resin is 0 ℃ or lower, and A method for manufacturing a radio wave absorber film, wherein the thickness of the radio wave absorbing layer is 10 μm or more and 50 μm or less.
In Article 8, A method for manufacturing a radio wave absorber film, comprising a cutting process for cutting a laminate having the substrate layer and the radio wave absorber layer obtained in the above radio wave absorber layer forming process to obtain a radio wave absorber film of a predetermined size.

Description

Radio wave absorber film, and method of manufacturing the same The present invention relates to a radio wave absorber film with excellent radio wave absorption performance and a method for manufacturing the same. The use of high-frequency radio waves is expanding in various information and communication systems, such as mobile phones, wireless LANs, ETC systems, highway traffic systems, vehicle assistance systems, and satellite broadcasting. However, this increased use of high-frequency waves raises concerns about potential failures or malfunctions in electronic devices caused by interference between electronic components. As a countermeasure to this problem, methods are being adopted to absorb unwanted radio waves using radio wave absorbers. For this reason, even in radars and the like that use high-frequency radio waves, radio wave absorbers are used to mitigate the effects of unnecessary radio waves that are not originally intended to be received. In response to such requirements, various electromagnetic wave absorbers capable of effectively absorbing electromagnetic waves in the high-frequency band have been proposed. Specific examples include, for instance, an electromagnetic wave absorbing sheet containing carbon nanocoils and a resin (e.g., Patent Document 1). Among the applications of radio waves in the high-frequency band, research is being conducted on automotive driver assistance systems. In such automotive driver assistance systems, radio waves in the 76 GHz band are used in onboard radars for detecting the distance between vehicles. Furthermore, it is predicted that the use of radio waves in high-frequency bands, such as those above 100 GHz, will expand to various applications, not limited to automotive driver assistance systems. For this reason, there is a demand for radio wave absorbers that can effectively absorb radio waves in the 76 GHz band or higher frequency bands. In response to such requirements, a radio wave absorber capable of effectively absorbing radio waves over a wide range in the high-frequency band has been proposed, for example, having a radio wave absorbing layer comprising a magnetic crystal made of an ε- Fe₂O₃ - based iron oxide (e.g., Patent Document 2, Non-patent Documents 1 to 3). Figure 1 is a diagram showing the reflection attenuation amount of the electromagnetic wave absorber film of Example 1. Figure 2 is a diagram showing the reflection attenuation amount of the electromagnetic wave absorber film of Example 2. Figure 3 is a diagram showing the reflection attenuation amount of the electromagnetic wave absorber film of Example 3. Figure 4 is a diagram showing the reflection attenuation amount of the electromagnetic wave absorber film of Example 4. Figure 5 is a diagram showing the reflection attenuation amount of the electromagnetic wave absorber film of Comparative Example 1. Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments and may be implemented with appropriate modifications within the scope of the purpose of the present invention. Also, in this specification, “∼” indicates the above or below unless specifically stated otherwise. ≪Radio Wave Absorber Film≫ The electromagnetic wave absorber film comprises an electromagnetic wave absorbing layer formed on a substrate layer. The electromagnetic wave absorbing layer comprises a magnetic material and a binder resin. The binder resin comprises an aromatic ester-urethane copolymer. By incorporating a magnetic material and an aromatic ester-urethane copolymer as a binder resin into the electromagnetic wave absorption layer, an electromagnetic wave absorber film with excellent electromagnetic wave absorption properties can be manufactured even in the form of a thin film. With respect to the electromagnetic wave absorber film, a frequency band of 30 gigahertz (GHz) or higher is preferred, preferably 30 GHz or higher and 300 GHz or lower, and more preferably 40 GHz or higher and 200 GHz or lower, in order to more reliably absorb electromagnetic waves of high frequencies above the millimeter wave band. In the amount of reflection attenuation measured from the side of the surface having the electromagnetic wave absorption layer, it is preferred that there be a peak with an absolute value of 30 dB or higher. Unless otherwise specified, the value of the transmission attenuation amount shall be the value measured under the conditions of the embodiments described below. The shape of the electromagnetic wave absorber film may have a curved surface or consist only of a flat surface, and a flat shape is preferred. The thickness of the electromagnetic wave absorber film is preferably 1000 μm or less, more preferably 900 μm or less, even more preferably 450 μm or less, and particularly preferably 200 μm or less, from the perspective of making the film thinner or smaller without hindering the effects of the present invention. The thickness of t