US009311949B2  c12)  United States Patent  Omura et al.  (54)  MAGNETIC POWDER AND METHOD OF  MANUFACTURING THE SAME  (IO)  Patent No.:  US 9,311,949 B2  Apr. 12, 2016  (45)  Date of Patent:  (71)  Applicant:  FUJIFILM Corporation,  Minato-ku,  Tokyo (JP)  (72)  Inventors:  Kazufumi Omura,  Minami-ashigara  (JP);  Masahiko Mori,  Minami-ashigara  (JP)  (73)  Assignee:  FUJIFILM Corporation,  Tokyo (JP)  ( *)  Notice:  Subject to any disclaimer, the term ofthis  patent is extended or adjusted under 35  U.S.C. 154(b) by  O  days.  (21)  Appl. No.:  14/755,395  (22)  Filed:  Jun.30,2015  (65)  Prior Publication Data  Related U.S. Application Data  (57)  ABSTRACT  9 Claims, No Drawings  OTHER PUBLICATIONS  FOREIGN PATENT DOCUMENTS  (56)  References Cited  U.S. PATENT DOCUMENTS  USPC ........................................................ 23/313 R  See application file for complete search history.  Office Action dated Mar. 4, 2014 in Japanese Application No. 2011- 236602.  Office Action dated Oct. 1, 2013 in Japanese Application No.2011- 236602.  Primary Examiner  - Edward Johnson  (74)  Attorney, Agent, or Firm  - Sughrue Mion, PLLC  An aspect of the present invention relates to a method of  manufacturing magnetic powder, which comprises adding an  alkali metal salt compound comprising a substituent selected  from the group consisting of an alkali metal salt of a carboxyl  group and an alkali metal salt of a hydroxyl group to a water› based magnetic liquid comprising magnetic particles dis› persed in an acidic water-based solvent to cause the magnetic  particles to aggregate in the water-based magnetic liquid; and  collecting the aggregated magnetic particles to obtain the  magnetic powder.  US 2015/0302880 Al  Oct. 22, 2015  (62)  Division of application No. 13/661,964, filed on Oct.  26, 2012, now Pat. No. 9,117,581.  (51)  Int. Cl.  (52)  U.S. Cl.  CPC ............  GllB  51842  (2013.01);  GllB  5170678  (2013.01);  H0JF 1111  (2013.01)  ( 58)  Field of Classification Search  CPC .................................. C05B 19/00; C22B 1/14  (30)  Foreign Application Priority Data  Oct. 28, 2011  (JP) ................................. 2011-236602  6,677,036 B2  2003/0143323 Al  1/2004 Noguchi et al.  7/2003 Noguchi et al.  JP  JP  JP  JP  JP  JP  61-250831 A  01-232530  A  03-116414 A  05-299217  A  08-183618 A  2003-132531  A  11/1986  9/1989  5/1991  11/1993  7 /1996  5/2003  C22B 1114  GllB 51842  GllB 51706  H0JF Jill  (2006.01)  (2006.01)  (2006.01)  (2006.01) 