Patents by Inventor Takaaki Kuwana
Takaaki Kuwana 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: 5610262Abstract: In a process for producing a polycarbonate by subjecting a dihydroxy compound and a diester of carbonic acid to melt polycondensation through transesterification, after a polycarbonate prepolymer is prepared in the first-stage reaction, polycondensation is conducted as the second-stage reaction in a residence time in the range of from 15 to less than 60 min or through the use of at least one paddle-type self-cleaning twin-screw extruderThis process enables a colorless, transparent polycarbonate having a high molecular weight to be produced at a high efficiency on an industrial scale.Type: GrantFiled: April 7, 1995Date of Patent: March 11, 1997Assignee: Daicel Chemical Industries, Ltd.Inventors: Tsutomu Yamato, Yasuhiro Oshino, Yutaka Fukuda, Tatsuya Kanno, Takaaki Kuwana
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Patent number: 5548041Abstract: A polycarbonate is produced by transesterification from a dihydroxy compound such as 2,2-bis(4-hydroxyphenyl)propane and a diester of carbonic acid such as bisphenyl carbonate in a reactor made of stainless steel and treated by electropolishing or acid pickling or buffed on a surface part thereof which contacts the reactants. As the transesterification catalyst, (a) a nitrogen-containing, electron-donating compound and (b) a nitrogen-containing, electron-donating compound and an alkali metal compound or an alkaline earth metal compound are preferably used.Type: GrantFiled: August 29, 1995Date of Patent: August 20, 1996Assignee: Daicel Chemical Industries, Ltd.Inventors: Tsutomu Yamato, Yasuhiro Oshino, Yutaka Fukuda, Tatsuya Kanno, Takaaki Kuwana, Yoshimichi Okano
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Patent number: 5489665Abstract: A polycarbonate is produced by transesterification from a dihydroxy compound such as 2,2-bis(4-hydroxyphenyl)propane and a diester of carbonic acid such as bisphenyl carbonate in the presence of a substance which contains iron in an amount of 50% by weight or less and contacts the reactants. Alternatively, a polycarbonate is produced by transesterification from a dihydroxy compound and a diester of carbonic acid in a reactor made of stainless steel and treated by electropolishing or acid pickling or buffed on a surface part thereof which contacts the reactants. As the transesterification catalyst, (a) a nitrogen-containing, electron-donating compound and (b) a nitrogen-containing, electron-donating compound and an alkali metal compound or an alkaline earth metal compound are preferably used.Type: GrantFiled: October 21, 1994Date of Patent: February 6, 1996Assignee: Daicel Chemical Industries, Ltd.Inventors: Tsutomu Yamato, Yasuhiro Oshino, Yutaka Fukuda, Tatsuya Kanno, Takaaki Kuwana, Yoshimichi Okano
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Patent number: 5468836Abstract: A polycarbonate which is not discolored and is substantially free from chlorine ions causative of discoloration, has a branching parameter G of 0.1 to 1.0 and, terminal hydroxyl groups of 20 mole % or below based on all the terminal groups of the polycarbonate, and/or, a chlorine ion concentration in the polycarbonate of 10 ppm or below, and/or, a total of an alkali metal ion concentration and an alkaline earth metal ion concentration in the polycarbonate of 1 ppm or below. A process for preparing the above polycarbonate by the melt transesterification process which comprises using a nitrogenous basic compound (a), and/or, a compound (b) containing an element selected from the group consisting of Groups IIb, IVb and Vb of the periodic table; or, a nitrogenous basic compound (a), and, a compound (c) containing an element selected from the group consisting of alkali metals and alkaline earth metals, as a transesterification catalyst.Type: GrantFiled: September 13, 1993Date of Patent: November 21, 1995Assignee: Daicel Chemical Industries, Ltd.Inventors: Yoshimichi Okano, Tatsuya Kanno, Tsutomu Yamato, Yasuhiro Oshino, Michiyo Tanigawa, Takaaki Kuwana, Yutaka Fukuda
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Patent number: 5434227Abstract: A polycarbonate is produced by transesterification from a dihydroxy compound such as 2,2-bis(4-hydroxyphenyl)propane and a diester of carbonic acid such as bisphenyl carbonate in the presence of a substance containing iron in an amount of 50% by weight or less to contact the reactants. Also, a polycarbonate is produced by transesterification from a dihydroxy compound and a diester of carbonic acid in a reactor made of stainless steel and treated by electropolishing or acid pickling or buffed on a surface part thereof to contact the reactants. As the transesterification catalyst, (a) a nitrogen-containing, electron-donating compound and (b) a nitrogen-containing, electron-donating compound and an alkali metal compound or an alkaline earth metal compound are preferably used.Type: GrantFiled: March 16, 1992Date of Patent: July 18, 1995Assignee: Daicel Chemical Industries, Ltd.Inventors: Tsutomu Yamato, Yasuhiro Oshino, Yutaka Fukuda, Tatsuya Kanno, Takaaki Kuwana, Yoshimichi Okano
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Patent number: 5432250Abstract: In a process for producing a polycarbonate by subjecting a dihydroxy compound and a diester of carbonic acid to melt polycondensation through transesterification, after a polycarbonate prepolymer is prepared in the first-stage reaction, polycondensation is conducted as the second-stage reaction at a residence time in the range of from 15 to less than 60 min or through the use of at least one paddle-type self-cleaning twin-screw extruder.This process enables a colorless, transparent polycarbonate having a high molecular weight to be produced at a high efficiency on an industrial scale.Type: GrantFiled: November 18, 1992Date of Patent: July 11, 1995Assignee: Daicel Chemical Industries, Ltd.Inventors: Tsutomu Yamato, Yasuhiro Oshino, Yutaka Fukuda, Tatsuya Kanno, Takaaki Kuwana
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Patent number: 5418314Abstract: In a process for producing a polycarbonate by subjecting a dihydroxy compound and a diester of carbonic acid to melt polycondensation through transesterification, after a polycarbonate prepolymer is prepared in the first-stage reaction, polycondensation is conducted as the second-stage reaction at a residence time in the range of from 15 to less than 60 min or through the use of at least one paddle-type self-cleaning twin-screw extruder.This process enables a colorless, transparent polycarbonate having a high molecular weight to be produced at a high efficiency on an industrial scale.Type: GrantFiled: November 2, 1992Date of Patent: May 23, 1995Assignee: Daicel Chemical Industries, Ltd.Inventors: Tsutomu Yamamoto, Yasuhiro Oshino, Yutaka Fukuda, Tatsuya Kanno, Takaaki Kuwana
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Patent number: 5391690Abstract: A process for producing a (co)polycarbonate or a (co)polyestercarbonate having a high molecular weight and excellent hue, heat stability and mechanical properties by reacting a dihydroxyl compound with a diester of carbonic acid and/or a diester of dicarbonic acid in the presence of a transesterification catalyst, wherein at least part of the reaction process is conducted in the presence of a specified organic phosphorus compound, or, in the presence of a specified organic phosphorus compound and a hindered phenol compound. A (co)polycarbonate or (co)polyester-carbonate composition having excellent hue, heat stability and mechanical properties, comprising a (co)polycarbonate and/or a (co)polyestercarbonate and, a specified organic phosphorus compound, or, a specified organic phosphorus compound and a hindered phenol compound.Type: GrantFiled: June 2, 1993Date of Patent: February 21, 1995Assignee: Daicel Chemical Industries,Ltd.Inventors: Tatsuya Kanno, Tsutomu Yamato, Yasuhiro Oshino, Yutaka Fukuda, Yoshihiro Iguchi, Takaaki Kuwana, Toshihiro Matsumoto
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Patent number: 5387628Abstract: A process for producing a (co)polycarbonate or a (co)polyestercarbonate having a high molecular weight and excellent hue, heat stability and mechanical properties by reacting a dihydroxyl compound with a diester of carbonic acid and/or a diester of dicarbonic acid in the presence of a transesterification catalyst, wherein at least part of the reaction process is conducted in the presence of a specified organic phosphorus compound, or, in the presence of a specified organic phosphorus compound and a hindered phenol compound. A (co)polycarbonate or (co)polyester-carbonate composition having excellent hue, heat stability and mechanical properties, comprising a (co)polycarbonate and/or a (co)polyestercarbonate and, a specified organic phosphorus compound, or, a specified organic phosphorus compound and a hindered phenol compound.Type: GrantFiled: September 9, 1993Date of Patent: February 7, 1995Assignee: Daicel Chemical Industries, Ltd.Inventors: Tatsuya Kanno, Tsutomu Yamato, Yasuhiro Oshino, Yutaka Fukuda, Yoshihiro Iguchi, Takaaki Kuwana, Toshihiro Matsumoto
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Patent number: 5278279Abstract: A process for producing a (co)polycarbonate or a (co)polyestercarbonate having a high molecular weight and excellent hue, heat stability and mechanical properties by reacting a dihydroxyl compound with a diester of carbonic acid and/or a diester of dicarbonic acid in the presence of a transesterification catalyst, wherein at least part of the reaction process is conducted in the presence of a specified organic phosphorus compound, or, in the presence of a specified organic phosphorus compound and a hindered phenol compound. A (co)polycarbonate or (co)polyester-carbonate composition having excellent hue, heat stability and mechanical properties, comprising a (co)polycarbonate and/or a (co)polyestercarbonate and, a specified organic phosphorus compound, or, a specified organic phosphorus compound and a hindered phenol compound.Type: GrantFiled: August 31, 1992Date of Patent: January 11, 1994Assignee: Daicel Chemical Industries, Ltd.Inventors: Tatsuya Kanno, Tsutomu Yamato, Yasuhiro Oshino, Yutaka Fukuda, Yoshihiro Iguchi, Takaaki Kuwana, Toshihiro Matsumoto