公开(公告)号：WO1989011154A1

公开(公告)日：1989-11-16

申请号：PCT/US1989001901

申请日：1989-05-05

Applicant: EASTMAN KODAK COMPANY

Inventor： EASTMAN KODAK COMPANY ,  YUDELSON, Joseph, Samuel

IPC: H01F01/37

CPC classification number: G01N33/5434 ,  B03C1/01 ,  G01N2446/20 ,  G01N2446/30 ,  G01N2446/66 ,  G01N2446/84 ,  H01F1/445 ,  Y10T428/2991 ,  Y10T428/2998

Abstract: Stable, encapsulated superparamagnetic magnetite particles having a narrow particle size distribution with average particle diameters in the range of from 50 Å to 350 Å are prepared by forming an aqueous dispersion of magnetite particles having the above particle size characteristics in the presence of a surfactant, coacervating a mixture of gelatin and a carboxyl containing hydrophilic polymer such as gum arabic to form a thin coating of coacervate on the magnetite particles and crosslinking the coacervate coating with a gelatin hardener such as glutaraldehyde.