Patents by Inventor Koji Tsukuma
Koji Tsukuma 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: 10696022Abstract: A composite plate having a thickness of no more than 2 mm, and having laminated therein a zirconia sintered body, an adhesive layer, and a base material, the elasticity of the base material being no more than 100 GPa, and the apparent density of the composite plate being no more than 4.3 g/cm3.Type: GrantFiled: June 26, 2013Date of Patent: June 30, 2020Assignee: TOSOH CORPORATIONInventors: Isao Yamashita, Kohei Imai, Shoichi Yamauchi, Koji Tsukuma
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Patent number: 10682831Abstract: A composite plate has a thickness of 2 mm or less, which is obtained by laminating and closely fixing a zirconia sintered body and a fiber-reinforced plastic with each other, and the thickness ratio of the zirconia sintered body to the fiber-reinforced plastic is 0.01 to 1, and the apparent density of the composite plate is 4.3 g/cm3 or less. A composite plate has a thickness of 2 mm or less, which is obtained by laminating and closely fixing a zirconia sintered body and a fiber-reinforced plastic with each other, and the maximum roughness depth of the surface of the zirconia sintered body is 50 ?m or less per 1 cm2.Type: GrantFiled: December 5, 2013Date of Patent: June 16, 2020Assignee: TOSOH CORPORATIONInventors: Isao Yamashita, Kohei Imai, Shoichi Yamauchi, Koji Tsukuma
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Patent number: 9919971Abstract: To provide a zirconia sintered body which has at least two different color tones such as white and black, and which has no color bleeding or no gap between sintered bodies. A zirconia sintered body comprising a first zirconia sintered body and a second zirconia sintered body, characterized in that the first zirconia sintered body is a zirconia sintered body containing aluminum oxide; the second zirconia sintered body is a zirconia sintered body containing a spinel oxide; a bonding plane is formed between the first zirconia sintered body and the second zirconia sintered body; and it has no gap or no color bleeding at the bonding plane.Type: GrantFiled: December 25, 2014Date of Patent: March 20, 2018Assignee: TOSOH CORPORATIONInventors: Hitoshi Nagayama, Naoki Shinozaki, Takeshi Ito, Koji Tsukuma, Shoichi Yamauchi
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Publication number: 20160347666Abstract: To provide a zirconia sintered body which has at least two different color tones such as white and black, and which has no color bleeding or no gap between sintered bodies. A zirconia sintered body comprising a first zirconia sintered body and a second zirconia sintered body, characterized in that the first zirconia sintered body is a zirconia sintered body containing aluminum oxide; the second zirconia sintered body is a zirconia sintered body containing a spinel oxide; a bonding plane is formed between the first zirconia sintered body and the second zirconia sintered body; and it has no gap or no color bleeding at the bonding plane.Type: ApplicationFiled: December 25, 2014Publication date: December 1, 2016Applicant: TOSOH CORPORATIONInventors: Hitoshi NAGAYAMA, Naoki SHINOZAKI, Takeshi ITO, Koji TSUKUMA, Shoichi YAMAUCHI
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Patent number: 9249057Abstract: An object of the present invention is to provide a colored translucent zirconia sintered body having red color and high translucency. The present invention relates to a zirconia sintered body, characterized by containing 6 to 30 mo % of yttria and 0.1 to 5 mol % of cerium oxide in terms of CeO2, the cerium oxide containing an oxide of trivalent cerium. The zirconia sintered body of the present invention has, in addition of high hardness, diamond luster based on high refractive index inherent in zirconia, deep red color and transparency.Type: GrantFiled: March 4, 2011Date of Patent: February 2, 2016Assignee: TOSOH CORPORATIONInventor: Koji Tsukuma
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Patent number: 9249058Abstract: Translucent zirconia sintered bodies have had a problem that incorporation of titania improves translucency but lowers mechanical strength. The invention provides: a zirconia sintered body containing titanium oxide, the sintered body containing 6-15 mol % yttria and 3-20 mol % titania and having an in-line transmission of 50% or higher when examined at a sample thickness of 1 mm and a measuring wavelength of 600 nm; and a zirconia sintered body having especially high translucency which is a high-quality transparent zirconia sintered body that contains 3-20 mol % titania and 6-15 mol % yttria and has an in-line transmission, as measured at a wavelength of 600 nm, of 73% or higher and a haze value of 2.0% or less and that is highly translucent and is undimmed (cloudless). The invention further relates to a production process in which a powder having the composition is molded and thereafter subjected to ordinary-pressure primary sintering and hot isostatic pressing (HIP) under specific conditions.Type: GrantFiled: January 30, 2014Date of Patent: February 2, 2016Assignee: TOSOH CORPORATIONInventors: Isao Yamashita, Masayuki Kudou, Koji Tsukuma
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Patent number: 9174877Abstract: A colored translucent zirconia sintered body contains a transition metal element as a coloring agent, having a clear color tone and high transparency, and being excellent in both design properties and esthetic properties, and its production process. A colored translucent zirconia sintered body includes yttria in an amount of at least 6 mol % and at most 15 mol % and at least one member selected from the group consisting of iron, nickel, manganese, cobalt, chromium, copper and vanadium in an amount of at least 0.02 mol % and at most 0.5 mol % as calculated as oxides, and having a porosity of at most 1,000 ppm. The average crystal grain size is preferably at most 60 ?m.Type: GrantFiled: November 4, 2011Date of Patent: November 3, 2015Assignee: TOSOH CORPORATIONInventors: Shoichi Yamauchi, Isao Yamashita, Koji Tsukuma
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Publication number: 20150283791Abstract: A composite plate has a thickness of 2 mm or less, which is obtained by laminating and closely fixing a zirconia sintered body and a fiber-reinforced plastic with each other, and the thickness ratio of the zirconia sintered body to the fiber-reinforced plastic is 0.01 to 1, and the apparent density of the composite plate is 4.3 g/cm3 or less. A composite plate has a thickness of 2 mm or less, which is obtained by laminating and closely fixing a zirconia sintered body and a fiber-reinforced plastic with each other, and the maximum roughness depth of the surface of the zirconia sintered body is 50 ?m or less per 1 cm2.Type: ApplicationFiled: December 5, 2013Publication date: October 8, 2015Applicant: TOSOH CORPORATIONInventors: Isao Yamashita, Kohei Imai, Shoichi Yamauchi, Koji Tsukuma
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Publication number: 20150174863Abstract: [Problem] To provide a composite plate comprising a zirconia sintered body and a base material, or a zirconia sintered body and a base material comprising at least one among a group includes strengthened glass, Bakelite, aluminum, and magnesium, said composite plate being capable of being suitably used in a case or a watch member, etc, for a mobile electronic device that is light weight and has excellent shock resistance and abrasion resistance. [Solution] A composite plate having a thickness of no more than 2 mm, and having laminated therein a zirconia sintered body, an adhesive layer, and a base material, the elasticity of the base material being no more than 100 GPa, and the apparent density of the composite plate being no more than 4.Type: ApplicationFiled: June 26, 2013Publication date: June 25, 2015Inventors: Isao Yamashita, Kohei Imai, Shoichi Yamauchi, Koji Tsukuma
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Patent number: 8815760Abstract: The subject of the present invention relates to obtaining a zirconia sintered body having excellent in both properties of a translucency and a mechanical strength. The present invention relates to obtaining a high-strength zirconia sintered body having a translucency of an in-line transmission of 50% or more at a sample thickness of 1 mm for visible light at a wavelength of 600 nm and an average flexural strength of 300 MPa or more by subjecting a zirconia primary sintered body having an average grain size of 1 ?m or less and a relative density of 92% or more and the crystal phase composed of cubic crystals only to HIP treatment at a temperature of 1,250° C. to 1,600° C. and a pressure of at least 50 MPa. The primary sintered body is obtained by maintaining a molded body of a zirconia powder containing 7 mol % to 30 mol % of yttria at 1,100° C. to 1,300° C. for at least 5 hrs or by heating the molded body at a high rate of temperature rise of 500° C./hr or more.Type: GrantFiled: July 15, 2010Date of Patent: August 26, 2014Assignee: Tosoh CorporationInventors: Masahiro Watanabe, Satoshi Kondoh, Koji Tsukuma
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Patent number: 8785008Abstract: The invention relates to the use of a sintered body obtained by subjecting a primary sintered body having a relative density of 95% or higher produced from a fine yttria-containing zirconia powder to HIP sintering at a temperature of 1,200-1,600° C. and a pressure of 50 MPa or higher. This sintered body is either a sintered body which has a total light transmittance, as measured at a thickness of 0.5 mm, of 43% or higher and a three-point bending strength of 1,700 MPa or higher or a zirconia sintered body which has a total light transmittance, as measured at a thickness of 1 mm, of 40% or higher and a three-point bending strength of 500 MPa or higher and which combines high strength and total light transmission.Type: GrantFiled: July 19, 2007Date of Patent: July 22, 2014Assignee: Tosoh CorporationInventors: Isao Yamashita, Koji Tsukuma, Toru Tsuyoshi
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Publication number: 20140145125Abstract: Translucent zirconia sintered bodies have had a problem that incorporation of titania improves translucency but lowers mechanical strength. The invention provides: a zirconia sintered body containing titanium oxide, the sintered body containing 6-15 mol % yttria and 3-20 mol % titania and having an in-line transmission of 50% or higher when examined at a sample thickness of 1 mm and a measuring wavelength of 600 nm; and a zirconia sintered body having especially high translucency which is a high-quality transparent zirconia sintered body that contains 3-20 mol % titania and 6-15 mol % yttria and has an in-line transmission, as measured at a wavelength of 600 nm, of 73% or higher and a haze value of 2.0% or less and that is highly translucent and is undimmed (cloudless). The invention further relates to a production process in which a powder having the composition is molded and thereafter subjected to ordinary-pressure primary sintering and hot isostatic pressing (HIP) under specific conditions.Type: ApplicationFiled: January 30, 2014Publication date: May 29, 2014Applicant: TOSOH CORPORATIONInventors: Isao YAMASHITA, Masayuki KUDOU, Koji TSUKUMA
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Patent number: 8722555Abstract: Translucent zirconia sintered bodies have had a problem that incorporation of titania improves translucency but lowers mechanical strength. The invention provides: a zirconia sintered body containing titanium oxide, the sintered body containing 6-15 mol % yttria and 3-20 mol % titania and having an in-line transmission of 50% or higher when examined at a sample thickness of 1 mm and a measuring wavelength of 600 nm; and a zirconia sintered body having especially high translucency which is a high-quality transparent zirconia sintered body that contains 3-20 mol % titania and 6-15 mol % yttria and has an in-line transmission, as measured at a wavelength of 600 nm, of 73% or higher and a haze value of 2.0% or less and that is highly translucent and is undimmed (cloudless). The invention further relates to a production process in which a powder having the composition is molded and thereafter subjected to ordinary-pressure primary sintering and hot isostatic pressing (HIP) under specific conditions.Type: GrantFiled: June 3, 2010Date of Patent: May 13, 2014Assignee: Tosoh CorporationInventors: Isao Yamashita, Masayuki Kudou, Koji Tsukuma
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Publication number: 20130217562Abstract: A colored translucent zirconia sintered body contains a transition metal element as a coloring agent, having a clear color tone and high transparency, and being excellent in both design properties and esthetic properties, and its production process. A colored translucent zirconia sintered body includes yttria in an amount of at least 6 mol % and at most 15 mol % and at least one member selected from the group consisting of iron, nickel, manganese, cobalt, chromium, copper and vanadium in an amount of at least 0.02 mol % and at most 0.5 mol % as calculated as oxides, and having a porosity of at most 1,000 ppm. The average crystal grain size is preferably at most 60 ?m.Type: ApplicationFiled: November 4, 2011Publication date: August 22, 2013Applicant: TOSOH CORPORATIONInventors: Shoichi Yamauchi, Isao Yamashita, Koji Tsukuma
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Patent number: 8481439Abstract: Because fracture toughness and translucency of translucent colored alumina sintered body of the past were low, the alumina sintered body was not suitable for uses such as dental materials, which require high toughness. The present invention relates to providing a translucent colored alumina sintered body that contains transition metal oxides, and with which the fracture toughness is 4.5 MPa·m0.5 or more and the maximum value of total forward transmittance (sample thickness 1 mm) to a wavelength of 300-800 nm is 60% or more. The present invention relates to obtaining a sintered body, at least 20% of which contains anisotropic grains with a long axis length of 10 ?m or greater and an aspect ratio of 1.Type: GrantFiled: November 13, 2009Date of Patent: July 9, 2013Assignee: Tosoh CorporationInventors: Isao Yamashita, Koji Tsukuma
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Publication number: 20130037763Abstract: An object of the present invention is to provide a colored translucent zirconia sintered body having red color and high translucency. The present invention relates to a zirconia sintered body, characterized by containing 6 to 30 mo % of yttria and 0.1 to 5 mol % of cerium oxide in terms of CeO2, the cerium oxide containing an oxide of trivalent cerium. The zirconia sintered body of the present invention has, in addition of high hardness, diamond luster based on high refractive index inherent in zirconia, deep red color and transparency.Type: ApplicationFiled: March 4, 2011Publication date: February 14, 2013Applicant: TOSOH CORPORATIONInventor: Koji Tsukuma
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Publication number: 20120212890Abstract: There is provided a cover which is formed of a transparent ceramic including metal oxide crystals, and which is disposed on part of a housing of an electronic device such that the cover covers at least part of a surface of a touch panel that is housed inside the housing.Type: ApplicationFiled: February 16, 2012Publication date: August 23, 2012Inventors: Hironari Hoshino, Masahiko Kakizaki, Takaaki Kawakami, Isao Yamashita, Koji Tsukuma
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Patent number: 8215019Abstract: A method for producing an orthodontic bracket is comprised of sintering a molded body of highly-pure alumina fine powder at a temperature of 1,200° C. to 1,300° C. to obtain a sintered body composed of crystals having a relative density of 96% to 99.5% and an average crystal grain size of at most 1 ?m, and thereafter subjecting the sintered body to an HIP treatment at a temperature of 1,200° C. to 1,350° C., under a pressure of at least 50 MPa. Such an orthodontic bracket has high strength and high translucency, can be processed into a complicated shape, similar to that of a metal bracket, and maintains excellent translucency.Type: GrantFiled: December 19, 2008Date of Patent: July 10, 2012Assignee: Tosoh CorporationInventors: Koji Tsukuma, Toru Tsuyoshi
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Publication number: 20120094823Abstract: The subject of the present invention relates to obtaining a zirconia sintered body having excellent in both properties of a translucency and a mechanical strength. The present invention relates to obtaining a high-strength zirconia sintered body having a translucency of an in-line transmission of 50% or more at a sample thickness of 1 mm for visible light at a wavelength of 600 nm and an average flexural strength of 300 MPa or more by subjecting a zirconia primary sintered body having an average grain size of 1 ?m or less and a relative density of 92% or more and the crystal phase composed of cubic crystals only to HIP treatment at a temperature of 1,250° C. to 1,600° C. and a pressure of at least 50 MPa. The primary sintered body is obtained by maintaining a molded body of a zirconia powder containing 7 mol % to 30 mol % of yttria at 1,100° C. to 1,300° C. for at least 5 hrs or by heating the molded body at a high rate of temperature rise of 500° C./hr or more.Type: ApplicationFiled: July 15, 2010Publication date: April 19, 2012Applicant: TOSOH CORPORATIONInventors: Masahiro Watanabe, Satoshi Kondoh, Koji Tsukuma
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Patent number: 8133051Abstract: An orthodontic bracket is comprised of a translucent ceramic containing at least 99.5 wt % of alumina, and having an absorption/scattering coefficient of at most 2.8 mm?1 for visible light at a wavelength of 550 nm and a bending strength of, at least 700 MPa. This bracket is obtained, for example, by sintering a molded body of highly-pure alumina fine powder at a temperature of from 1,200° C. to 1,300° C. to obtain a sintered body composed of crystals having a relative density of from 96% to 99.5% and an average crystal grain size of at most 1 ?m, and thereafter subjecting the sintered body to an HIP treatment at a temperature of from 1,200° C. to 1,350° C. and under a pressure of at least 50 MPa. Such an orthodontic bracket has high strength and high translucency, can be processed into a complicated shape, similar to that of a metal bracket, and maintains excellent translucency.Type: GrantFiled: August 26, 2005Date of Patent: March 13, 2012Assignee: Tosoh CorporationInventors: Koji Tsukuma, Toru Tsuyoshi