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# c12) United States Patent Omura et al. 

# (54) MAGNETIC POWDER AND METHOD OF MANUFACTURING THE SAME 

(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 

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. 

## (30) Foreign Application Priority Data 

Oct. 28, 2011 (JP) ................................. 2011-236602 

(51) Int. Cl. 

<img src='content_image/936013.jpg'>

(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 

## Related U.S. Application Data 

<img src='content_image/935978.jpg'>

# (IO) Patent No.: US 9,311,949 B2 

# Apr. 12, 2016 (45) Date of Patent: 

## (56) References Cited 

<img src='content_image/936011.jpg'>

<img src='content_image/936012.jpg'>

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 

## (57) ABSTRACT 

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. 

USPC ........................................................ 23/313 R See application file for complete search history. 

US009311949B2 

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## 9 Claims, No Drawings 

