Patents by Inventor Yasutaka Ota
Yasutaka Ota has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7172642Abstract: Magnetic metal particles containing iron as a main component, comprising cobalt in an amount of usually 20 to 50 atm %, calculated as Co, based on whole Fe, aluminum in an amount of usually 3 to 15 atm %, calculated as Al, based on whole Fe and a rare earth element in an amount of usually 3 to 20 atm %, calculated as rare earth element, based on whole Fe, and having an average major axis diameter of usually 0.02 to 0.065 ?m, preferably from 0.02 to less than 0.05 ?m, a coercive force of usually 159.2 to 222.9 kA/m (2,000 to 2,800 Oe), a soluble Na content of usually not more than 30 ppm, a soluble Ca content of usually not more than 100 ppm, and an oxidation stability ??s of usually not more than 10%.Type: GrantFiled: November 27, 2002Date of Patent: February 6, 2007Assignee: Toda Kogyo CorporationInventors: Akinori Yamamoto, Yasutaka Ota, Haruki Kurokawa, Masaaki Maekawa
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Patent number: 6753084Abstract: Spindle-shaped magnetic alloy particles containing Fe and Co as main components of the present invention have a cobalt content of 20 to 50 atm % (calculated as Co) based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 &mgr;m; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 100 to 160 Å; and an activation volume (Vact) of 0.01 to 0.07E-4 &mgr;m3. A high-density magnetic recording medium produced by using such spindle-shaped magnetic alloy particles containing Fe and Co as main components, have an excellent output characteristics in a short wavelength region, a considerably reduced noise and an excellent storage stability.Type: GrantFiled: December 20, 2001Date of Patent: June 22, 2004Assignee: Toda Kogyo CorporationInventors: Masaaki Maekawa, Haruki Kurokawa, Kenji Okinaka, Akinori Yamamoto, Yasutaka Ota
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Patent number: 6682813Abstract: Magnetic acicular alloy particles containing iron as a main component according to the present invention, have an average major axial diameter of 0.05 to 0.2 &mgr;m, and pH values of water suspensions of said magnetic acicular alloy particles containing iron as a main component, which satisfies the formula: (pH value of water suspension treated by A method)−(pH value of water suspension treated by B method)<0 Such magnetic acicular alloy particles containing iron as a main component exhibit an excellent dispersibility in a vehicle, especially such a vehicle composed of a binder resin having a polar group such as —SO3M (wherein M is H, Na or K), —COOH or the like, and in which an orientation and a packing density in coating film are improved.Type: GrantFiled: July 17, 2002Date of Patent: January 27, 2004Assignee: Toda Kogyo CorporationInventors: Kohji Mori, Yasutaka Ota
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Publication number: 20030136473Abstract: Magnetic metal particles containing iron as a main component, comprising cobalt in an amount of usually 20 to 50 atm %, calculated as Co, based on whole Fe, aluminum in an amount of usually 3 to 15 atm %, calculated as Al, based on whole Fe and a rare earth element in an amount of usually 3 to 20 atm %, calculated as rare earth element, based on whole Fe, and having an average major axis diameter of usually 0.02 to 0.065 &mgr;m, preferably from 0.02 to less than 0.05 &mgr;m, a coercive force of usually 159.2 to 222.9 kA/m (2,000 to 2,800 Oe), a soluble Na content of usually not more than 30 ppm, a soluble Ca content of usually not more than 100 ppm, and an oxidation stability &Dgr;&sgr;s of usually not more than 10%.Type: ApplicationFiled: November 27, 2002Publication date: July 24, 2003Inventors: Akinori Yamamoto, Yasutaka Ota, Haruki Kurokawa, Masaaki Maekawa
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Publication number: 20030044648Abstract: Magnetic acicular alloy particles containing iron as a main component according to the present invention, have an average major axial diameter of 0.05 to 0.Type: ApplicationFiled: July 17, 2002Publication date: March 6, 2003Applicant: Toda Kogyo CorporationInventors: Kohji Mori, Yasutaka Ota
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Publication number: 20020155323Abstract: Spindle-shaped magnetic alloy particles containing Fe and Co as main components of the present invention have a cobalt content of 20 to 50 atm% (calculated as Co) based on whole Fe; an average major axis diameter (L) of 0.03 to 0.10 &mgr;m; a coercive force value of 159.2 to 238.7 kA/m (2,000 to 3,000 Oe); a crystallite size of 100 to 160 Å; and an activation volume (Vact) of 0.01 to 0.07E-4 &mgr;m3. A high-density magnetic recording medium produced by using such spindle-shaped magnetic alloy particles containing Fe and Co as main components, have an excellent output characteristics in a short wavelength region, a considerably reduced noise and an excellent storage stability.Type: ApplicationFiled: December 20, 2001Publication date: October 24, 2002Inventors: Masaaki Maekawa, Haruki Kurokawa, Kenji Okinaka, Akinori Yamamoto, Yasutaka Ota
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Patent number: 6447618Abstract: Magnetic acicular alloy particles containing iron as a main component according to the present invention, have an average major axial diameter of 0.05 to 0.2 &mgr;m, and pH values of water suspensions of said magnetic acicular alloy particles containing iron as a main component, which satisfies the formula: (pH value of water suspension treated by A method)−(pH value of water suspension treated by B method)<0 Such magnetic acicular alloy particles containing iron as a main component exhibit an excellent dispersibility in a vehicle, especially such a vehicle composed of a binder resin having a polar group such as —SO3M (wherein M is H, Na or K), —COOH or the like, and in which an orientation and a packing density in coating film are improved.Type: GrantFiled: July 27, 1999Date of Patent: September 10, 2002Assignee: Toda Kogyo CorporationInventors: Kohji Mori, Yasutaka Ota
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Patent number: 5989516Abstract: The present invention relates to a spindle-shaped goethite particles containing cobalt of 8.0 to 50.0 atm %, calculated as Co, based on the total Fe in the spindle-shaped goethite particles and a compound of at least one element selected from the group consisting of Al, Si, Nd, Y, La, Ce, Pr, Tb, Ca, Mg, Ba and Sr of not more than 25.0 atm %, calculated as the element, based on the total Fe in the spindle-shaped goethite particles, and having an average major axis diameter of 0.05 to 0.15 .mu.m, a size distribution (standard deviation/major axis diameter) of not more than 0.30, an average minor axis diameter of 0.010 to 0.025 .mu.m, an aspect ratio of 4 to 8 and an X-ray crystallite size ratio (D.sub.020 /D.sub.110) of 2.0 to 3.5.Type: GrantFiled: December 8, 1997Date of Patent: November 23, 1999Assignee: Toda Kogyo CorporationInventors: Kenji Okinaka, Yasutaka Ota
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Patent number: 5968226Abstract: The disclosure describes spindle-shaped magnetic iron-based alloy particles containing cobalt and iron as the main ingredients in which the Co content is 1.0 to 50.0 atm % (calculated as Co) based on the total Fe in the spindle-shaped magnetic iron-based alloy particles, and which the spindle-shaped magnetic iron-based alloy particles have an average major axis diameter of 0.05 to 0.18 .mu.m, a size distribution (standard deviation/major axis diameter) of not more than 0.25, an average minor axis diameter of 0.010 to 0.020 .mu.m, an aspect ratio (major axis diameter/minor axis diameter) of 4 to 15, an X-ray crystallite size D.sub.110 of 120 to 180 .ANG., a coercive force of 1720 to 2500 Oe, a saturation magnetization of not less than 110 emu/g, and a saturation magnetization decrement percentage of not more than 17%.Type: GrantFiled: December 31, 1996Date of Patent: October 19, 1999Assignee: Toda Kogyo CorporationInventors: Kenji Okinaka, Yasutaka Ota
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Patent number: 5735969Abstract: The present invention is a method for making highly stable magnetic alloy particles with high coercivities and high saturation magnetization comprising the steps of:a) providing a precursor selected from the group consisting of iron oxide hydroxide particles and iron oxide particles, wherein the precursor particle comprises from about 15 to about 45 atomic % Co based on amount of Fe present,b) reducing the precursor particles to magnetic alloy particles,c) passivating the magnetic alloy particles in an oxygen-containing atmosphere at a temperature between about 20.degree. and 100.degree. C.,d) annealing the passivated magnetic alloy particles in an inert atmosphere at a temperature from about 120.degree. to about 450.degree. C., ande) further oxidizing the annealed magnetic alloy particles in an oxygen-containing atmosphere.Type: GrantFiled: March 7, 1996Date of Patent: April 7, 1998Assignees: Imation Corp., Toda Kogyo Corp.Inventors: Jean A. Lown, Yasutaka Ota, Kenji Okinaka, Hirofumi Kawasaki
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Patent number: 5645652Abstract: The disclosure describes spindle-shaped magnetic iron-based alloy particles containing cobalt and iron as the main ingredients in which the Co content is 1.0 to 50.0 atm % (calculated as Co) based on the total Fe in the spindle-shaped magnetic iron-based alloy particles, and which the spindle-shaped magnetic iron-based alloy particles have an average major axis diameter of 0.05 to 0.18 .mu.m, a size distribution (standard deviation/major axis diameter) of not more than 0.25, an average minor axis diameter of 0.010 to 0.020 .mu.m, an aspect ratio (major axis diameter/minor axis diameter) of 4 to 15, an X-ray crystallite size D.sub.110 of 120 to 180 .ANG., a coercive force of 1720 to 2500 Oe, a saturation magnetization of not less than 110 emu/g, and a saturation magnetization decrement percentage of not more than 17%.Type: GrantFiled: May 1, 1995Date of Patent: July 8, 1997Assignee: Toda Kogyo CorporationInventors: Kenji Okinaka, Yasutaka Ota
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Patent number: 5599378Abstract: Disclosed herein are spindle-shaped magnetic iron based alloy particles containing at least one selected from the group consisting of Ni, Al, Si, P, Co, Mg, B and Zn, which have a particle length of 0.05 to 0.40 .mu.m, a crystallite size of 110 to 180 .ANG., a specific surface area of 30 to 60 m.sup.2 /g, a coercive force of 1,300 to 1,700 Oe and a saturation magnetization (.sigma.s) of not less than 100 emu/g and a process for producing the same.Type: GrantFiled: May 25, 1995Date of Patent: February 4, 1997Assignee: Toda Kogyo Corp.Inventors: Akio Mishima, Tosiharu Harada, Mamoru Tanihara, Yasutaka Ota, Kenji Okinaka, Kohji Mori, Hirofumi Kawasaki, Norimichi Nagai, Katsunori Fujimoto, Yoshiro Okuda
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Patent number: 5531922Abstract: Disclosed herein are granulated particles for magnetic particles for magnetic recording, comprising: acicular ferric hydroxide oxide particles or acicular iron oxide particles; and at least one selected from the group consisting of semisynthetic starch and semisynthetic cellulose and having a bulk density of not less than 0.3 g/cm.sup.3 and a powdering ratio of not more than 40%, and a process for producing the granulated particles, and magnetic particles obtained from such granulated particles.Type: GrantFiled: September 12, 1995Date of Patent: July 2, 1996Assignee: Toda Kogyo CorporationInventors: Kenji Okinaka, Yasutaka Ota, Kohji Mori, Hirofumi Kawasaki, Masayuki Uegami, Akio Mishima, Katsumi Yamashita, Minoru Yamasaki, Manabu Matsumoto, Kunihiro Kouchi, Hiroki Kamon
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Patent number: 5466306Abstract: Disclosed herein are spindle-shaped magnetic iron based alloy particles containing at least one selected from the group consisting of Ni, Al, Si, P, Co, Mg, B and Zn, which have a particle length of 0.05 to 0.40 .mu.m, a crystallite size of 110 to 180 .ANG., a specific surface area of 30 to 60 m.sup.2 /g, a coercive force of 1,300 to 1,700 Oe and a saturation magnetization (.sigma.s) of not less than 100 emu/g and a process for producing the same.Type: GrantFiled: September 9, 1993Date of Patent: November 14, 1995Assignee: Toda Kogyo Corp.Inventors: Akio Mishima, Tosiharu Harada, Mamoru Tanihara, Yasutaka Ota, Kenji Okinaka, Kohji Mori, Hirofumi Kawasaki, Norimichi Nagai, Katsunori Fujimoto, Yoshiro Okuda
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Acicular magnetic iron based alloy particles for magnetic recording and method of producing the same
Patent number: 5238483Abstract: Disclosed herein are acicular magnetic iron based alloy particles for magnetic recording, containing 1.5 to 10 mol % of B based on Fe (calculated as B) and 1.5 to 10 mol % of Co based on Fe (calculated as Co) in the vicinity of the surfaces of said particles and having a saturation magnetization of not less than 125 emu/g and an S.F.D. value of not more than 0.50, and a process for producing the same.Type: GrantFiled: July 29, 1992Date of Patent: August 24, 1993Assignee: Toda Kogyo CorporationInventors: Akio Mishima, Mamoru Tanihara, Yasutaka Ota, Hirofumi Kawasaki, Kenji Okinaka, Kunio Ikemoto, Kousaku Tamari, Kohji Mori, Norimichi Nagai -
Acicular magnetic iron based alloy particles for magnetic recording and method of producing the same
Patent number: 5156922Abstract: Disclosed herein are acicular magnetic iron based alloy particles for magnetic recording, containing 1.5 to 10 mol % of B based on Fe (calculated as B) and 1.5 to 10 mol % of Co based on Fe (calculated as Co) in the vicinity of the surfaces of said particles and having a saturation magnetization of not less than 125 emu/g and an S.F.D. value of not more than 0.50, and a process for producing the same.Type: GrantFiled: July 8, 1991Date of Patent: October 20, 1992Assignee: Toda Kogyo CorporationInventors: Akio Mishima, Mamoru Tanihara, Yasutaka Ota, Hirofumi Kawasaki, Kenji Okinaka, Kunio Ikemoto, Kousaku Tamari, Kohji Mori, Norimichi Nagai -
Patent number: 5137783Abstract: Disclosed herein are acicular magnetic metal particles containing iron as the main ingredient the surfaces of which are coated with a polymer formed from at least one of silicone compounds represented by the following formula (I):(R.sup.1 HSiO).sub.a (R.sup.2 R.sup.3 SiO).sub.b (R.sup.4 R.sup.5 R.sup.6 SiO.sub.1/2)c (I)wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 respectively represent a hydrogen atom or hydrocarbon group having 1 to 10 carbon atoms which hydrocarbon group may be substituted by at least one halogen atom, a and b are respectively 0 or integers of not less than 1, and c is 0 or 2, provided that when c is 0, the sum of a and b is an integer of not less than 3 and which have a coercive force of not less than 1400 Oe, a saturation magnetization of not less than 100 emu/g, a major axial diameter of not more than 0.25 .mu.m and an S.F.D. of not more than 0.38, and a process for producing the acicular magnetic metal particles containing iron as the main ingredient.Type: GrantFiled: April 2, 1990Date of Patent: August 11, 1992Assignees: Toda Kogyo Corporation, Shiseido Company, LimitedInventors: Mamoru Tanihara, Yasutaka Ota, Hiroshi Fukui, Takashi Ogawa, Tsuneo Suhara
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Patent number: 4851292Abstract: Disclosed herein are plate-like barium ferrite particles with a solid solution of zinc on the surface thereof, which have an average particle diameter of not less than 0.03 .mu.m and less than 0.1 .mu.m, a BET specific surface are of 55 to 80 m.sup.2 /g, a coercive force of 300 to 1,500 Oe and a magnetization of not less than 57 emu/g, preferably not less than 60 emu/g, in magnetic field of 10 KOe, and which are represented by the following formula (I):BaO.n[(Fe.sub.1-x-y Co.sub.x Ti.sub.y).sub.2 O.sub.3-x+y ] (I)wherein x and y are independently from 0.02 to 0.12 and n is from 4 to 11, the atomic ratio of Co to Fe(III) being from 0.02:1 to 0.13:1 and the molar ratio of Ti to Co being from more than 0 to not more than 0.8, and a process for producing the plate-like barium ferrite particles.Type: GrantFiled: January 29, 1987Date of Patent: July 25, 1989Assignee: Toda Kogyo Corp.Inventors: Norimichi Nagai, Akihiko Hirayama, Norio Sugita, Masao Kiyama, Toshio Takada, Katsunori Fujimoto, Yasutaka Ota
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Patent number: 4806429Abstract: Disclosed herein are plate-like barium ferrite particles with a solid solution of zinc on the surface thereof, which have an average particle diameter of 0.05 to 0.3 .mu.m, a coercive force of 300 to 1,500 Oe and a magnetization of not less than 55 emu/g in magnetic field of 10 KOe, and which are represented by the following formula (I):BaO.multidot.n[(Fe.sub.1-2x Co.sub.x Ti.sub.x).sub.2 O.sub.3 ](I)wherein x is 0 to 0.1 and n is from 4 to 11, the molar ratio of Ti to Co being 1, and a process for producing the plate-like barium ferrite particles.Type: GrantFiled: January 29, 1987Date of Patent: February 21, 1989Assignee: Toda Kogyo CorporationInventors: Norimichi Nagai, Akihiko Hirayama, Norio Sugita, Masao Kiyama, Toshio Takada, Katsunori Fujimoto, Yasutaka Ota
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Patent number: 4781981Abstract: Disclosed herein are Ba-containing plate-like magnetoplumbite type ferrite particles for magnetic recording containing ions of one metal (II) selected from Ni and Zn and ions of one metal (IV) selected from Ti, Sn and Zr, and having zinc incorporated as a solid solution close to the particle surface and the change of coercive force of said particles at a temperature of -20.degree. to 120.degree. C. in the range of -0.5 to +0.5 Oe/.degree.C., and a process for producing the same.Type: GrantFiled: December 7, 1987Date of Patent: November 1, 1988Assignee: Toda Kogyo Corp.Inventors: Tsutomu Katamoto, Norimichi Nagai, Yasutaka Ota, Katsunori Fujimoto, Akihiko Hirayama, Masao Kiyama