公开(公告)号：US20240145134A1

公开(公告)日：2024-05-02

申请号：US18175139

申请日：2023-02-27

Applicant: TDK CORPORATION

Inventor： Toshiki GUSHI ,  Kazuhiro YOSHIDOME ,  Akito HASEGAWA ,  Isao KANADA

IPC: H01F1/00 ,  G01N27/72

CPC classification number: H01F1/0054 ,  G01N27/72

Abstract: A polymer particle containing magnetic material includes a core and a polymer layer. The core includes magnetic fine particles. The polymer layer is located outside the core and surrounds the core. A shape ratio (Ric) is defined in each of the magnetic fine particles by dividing a diameter (Di) of an inscribed circle of the magnetic fine particle by a diameter (Do) of a circumscribed circle of the magnetic fine particle. The shape ratio (Ric) of the magnetic fine particle is 0.50 or more and 0.94 or less. The diameter (Di) of the magnetic fine particle is 5 nm or more. The diameter (Di) and the shape ratio (Ric) of the magnetic fine particle satisfy a relation formula of Di≤9.28×e{circumflex over ( )}(1.17×Ric).