| 摘要 |
PROBLEM TO BE SOLVED: To enhance the affinity between magnetic fine particles and perfluoropolyether base radical oil, thereby enabling them to be effectively used as a sealing material, etc., of a vacuum device by using perfluoroether carboxylic acid together with perfluoroehter alxylene ether carboxylic acid. SOLUTION: The magnetic fine particles are composed of perfluoroether carboxylic acid represented by a formula I (where M and n respectively represents hydrogen atom, alkali metal or ammonium radical; integer of 1-100) and perfluoroether (poly) alxylene ether carboxylic acid (where R, M, X, p, q respectively represents low grade alxylene radical; hydrogen atom, alkali metal; alkali earth metal or ammonium radical; -COO- radical or CH2 O- radical; integer of 1-100) to be dispersed in perfluoro poltyether base radical oil represented by another formula III (where Rf and m respectively represents perfluoro alkyl radical; integer of exceeding 1). |
