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公开(公告)号：US20210300779A1
公开(公告)日：2021-09-30
申请号：US16979241
申请日：2019-03-26
发明人： Shin-ichi OHKOSHI , Asuka NAMAI , Kenji SAKANE , Tetsuya KAWAHITO
摘要： [Problem] To provide a method for producing iron based oxide magnetic powder that has a narrow particle size distribution and a small content of fine particles that do not contribute to the magnetic recording characteristics, and consequently has a narrow coercive force distribution and is suitable for the enhancement of the recording density of the magnetic recording medium. [Solution] ε-Type iron based oxide magnetic powder is obtained by a wet method, then a tetraalkylammonium salt as a surface modifier is added to a slurry containing the magnetic powder to make a concentration of 0.009 mol/kg or more and 1.0 mol/kg or less, and simultaneously to make pH of 11 or more and 14 or less, and the slurry is subjected to a dispersion treatment and then classified, so as to provide iron based oxide magnetic powder having a narrow particle size distribution and a narrow coercive force distribution.
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公开(公告)号：US20190228889A1
公开(公告)日：2019-07-25
申请号：US16337195
申请日：2017-09-29
摘要： An object of the present invention is to provide a magnetic powder having a narrow particle size distribution of epsilon-type iron oxide particles, and another object is to provide magnetic powder suitable for magnetic recording medium by improving particle size distribution, and provide epsilon-type iron oxide magnetic particles and related technologies in which a number average particle diameter of major diameters (D50) is 10 to 20 nm, a 90% cumulative particle diameter (D90) is 30 nm or less, and a geometric standard deviation (σg) of major diameters is 1.45 or less, which are obtained by TEM observation.
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3.发明申请公开(公告)号：US20180005737A1
公开(公告)日：2018-01-04
申请号：US15541505
申请日：2015-12-28
发明人： Kenji SAKANE , Tetsuya KAWAHITO
IPC分类号： H01F1/03 , G11B5/842 , H01F1/00 , C01G49/06 , C01G51/00 , B82Y25/00 , H01F1/147 , G11B5/714 , B82Y40/00 , H01F1/153 , C01G53/00 , C01G23/00 , C01G45/00 , G01N23/20
CPC分类号： H01F1/0315 , B82Y25/00 , B82Y30/00 , B82Y40/00 , C01G23/003 , C01G45/006 , C01G49/0018 , C01G49/02 , C01G49/06 , C01G51/00 , C01G51/006 , C01G53/006 , C01P2002/52 , C01P2002/72 , C01P2004/04 , C01P2004/64 , C01P2006/42 , G01N23/20075 , G11B5/70642 , G11B5/712 , G11B5/714 , G11B5/842 , H01F1/0054 , H01F1/14725 , H01F1/15366
摘要： An iron-based oxide magnetic particle powder has a narrow particle size distribution a small content of fine particles that do not contribute to magnetic recording characteristics, and a narrow coercive force distribution, to enhance magnetic recording medium density. Neutralizing an aqueous solution containing a trivalent iron ion and an ion of the metal substituting a part of the Fe sites by adding an alkali to make pH of 1.5 or more and 2.5 or less, adding a hydroxycarboxylic acid, and further neutralizing by adding an alkali to make pH of 8.0 or more and 9.0 or less are performed at 5° C. or more and 25° C. or less. A formed iron oxyhydroxide precipitate containing the substituting metal element is rinsed with water, then coated with silicon oxide, and then heated thereby providing e-type iron-based oxide magnetic particle powder. The rinsed precipitate may be subjected to a hydrothermal treatment.
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公开(公告)号：US20220392676A1
公开(公告)日：2022-12-08
申请号：US17773865
申请日：2020-11-19
发明人： Hidefumi FUJITA , Koji TANOUE , Keisuke YAMADA , Tetsuya KAWAHITO
摘要： A silicon oxide-coated soft magnetic powder, in which the ratio of a volume-based cumulative 50% particle diameter D50 (HE) according to a dry laser diffraction particle size distribution analysis to the same particle diameter D50 (MT) according to a wet laser diffraction particle size distribution analysis is 0.7 or more, and a coverage ratio R defined by R=Si×100/(Si+M) (Si and M are molar fractions of Si and elements constituting the soft magnetic powder) is 70% or more is obtained by subjecting a slurry containing a soft magnetic powder containing 20 mass % or more of iron and a hydrolysate of a silicon alkoxide to a dispersion treatment when the surface of the soft magnetic powder is coated with the hydrolysate in a mixed solvent of water and an organic substance. The powder has good insulation/dispersibility properties and a high filling factor during molding.
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5.发明申请公开(公告)号：US20180033528A1
公开(公告)日：2018-02-01
申请号：US15552283
申请日：2016-03-11
发明人： Kenji SAKANE , Tetsuya KAWAHITO
CPC分类号： H01F1/14733 , C01F7/34 , C01F17/0025 , C01F17/0043 , C01G49/06 , C01G51/40 , C01P2002/52 , C01P2004/64 , C01P2004/84 , C01P2006/11 , C01P2006/12 , C01P2006/42 , G11B5/70615 , G11B5/70621 , G11B5/70642 , G11B5/712 , G11B5/714 , G11B5/84 , H01F1/11
摘要： A surface-modified iron-based oxide magnetic particle powder has good solid-liquid separation property in the production process, has good dispersibility in a coating material for forming a coating-type magnetic recording medium, has good orientation property, and has a small elution amount of a water-soluble alkali metal, and to provide a method for producing the surface-modified iron-based oxide magnetic particle powder. The surface-modified iron-based oxide magnetic particle powder can be obtained by neutralizing a solution containing dissolved therein a trivalent iron ion and an ion of the metal, by which the part of Fe sites is to be substituted, with an alkali aqueous solution, so as to provide a precursor, coating a silicon oxide on the precursor, heating the precursor to provide e-type iron-based oxide magnetic powder, and adhering a hydroxide or a hydrous oxide of one kind or two kinds of Al and Y thereto.
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公开(公告)号：US20180208479A1
公开(公告)日：2018-07-26
申请号：US15746459
申请日：2016-07-26
发明人： Kenji SAKANE , Tetsuya KAWAHITO
CPC分类号： C01G51/40 , C01G49/00 , C01G49/06 , C01P2002/50 , C01P2002/52 , C01P2002/72 , C01P2004/04 , C01P2004/64 , C01P2006/42 , G11B5/70621 , G11B5/70642 , G11B5/714 , H01F1/11
摘要： To provide iron-based oxide magnetic particle powder that has a narrow particle size distribution and a small content of fine particles that do not contribute to the magnetic recording characteristics, which result in a narrow coercive force distribution, and is suitable for the enhancement of the recording density of the magnetic recording medium, and a method for producing the same. An alkali is added to an aqueous solution containing a trivalent iron ion and an ion of the metal substituting a part of Fe sites to neutralize the aqueous solution to pH of 1.0 or more and 3.0 or less; a hydroxycarboxylic acid D is added in an amount providing a molar ratio D/Fe with respect to the amount of the trivalent iron ion or a molar ratio (D/(Fe+M)) with respect to the total amount of the trivalent iron ion and the ion of the metal M in the case where the substituting metal ion is contained of 0.125 or more and 1.0 or less; an alkali is further added to neutralize to pH of 7.0 or more and 10.0 or less; and then the iron oxyhydroxide containing the substituting metal element is coated with a silicon oxide and heated, so as to provide ε-type iron-based oxide magnetic particle powder containing the substituting metal element.
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7.发明申请公开(公告)号：US20170287516A1
公开(公告)日：2017-10-05
申请号：US15511038
申请日：2015-09-17
发明人： Kenji SAKANE , Tetsuya KAWAHITO
CPC分类号： G11B5/653 , B82Y25/00 , B82Y30/00 , B82Y40/00 , C01G49/0018 , C01G49/06 , C01G51/40 , C01P2002/50 , C01P2002/52 , C01P2002/72 , C01P2004/04 , C01P2004/51 , C01P2004/64 , C01P2006/42 , G11B5/70642 , G11B5/714 , H01F1/11 , Y10S977/773 , Y10S977/811 , Y10S977/896 , Y10S977/943
摘要： An e-type iron-based oxide magnetic particle powder has narrow particle size distribution and has a low content of fine particles which do not contribute to magnetic recording characteristics. As a result, a narrow coercive force distribution is achieved and the powder is suitable for increasing recording density of a magnetic recording medium. The powder containing substituting metal elements can be obtained by: adding an alkali to an aqueous solution containing trivalent iron ions and ions of the metals for partially substituting Fe sites to neutralize the aqueous solution to a pH of 1.5 to 2.5; then adding a hydroxycarboxylic acid; further adding the alkali to neutralize the aqueous solution to a pH of 8.0 to 9.0; washing with water a precipitation of an iron oxyhydroxide containing the substituting metal elements produced; and coating the iron oxyhydroxide containing the substituting metal elements with a silicon oxide and heating the resultant.
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公开(公告)号：US20220375663A1
公开(公告)日：2022-11-24
申请号：US17764229
申请日：2020-09-29
发明人： Shin-ichi OHKOSHI , Asuka NAMAl , Hiroko TOKORO , Marie YOSHIKIYO , Kazuhiro YAMAGA , Yasuto MIYAMOTO , Yuki MINEYAMA , Kenji SAKANE , Tetsuya KAWAHITO
摘要： A raw material solution containing trivalent iron ions, or trivalent iron ions and ions of a metal element that partially substitutes Fe sites, and an alkaline aqueous solution for neutralizing the raw material solution are added to a reaction system to adjust the pH of the reaction system from 1.0 to 3.0 or lower. Hydroxycarboxylic acid is added to the obtained reaction solution and the pH of the reaction system is then neutralized from 7.0 to 10.0 or lower. The obtained precipitate of a substituent metal element-containing iron oxyhydroxide is coated with silicon oxide, followed by heating so as to form particles of ε-iron oxide in which Fe sites are partially substituted by other metal elements, and then, a slurry containing the particles is classified. The iron-based oxide magnetic powder has a particle shape close to a perfect sphere and is suitable for use in a magnetic recording medium.
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