Patents by Inventor Tadashi Okawa

Tadashi Okawa 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).

  • Publication number: 20010031886
    Abstract: A method for synthesizing 1,3-dihydroxytetramethyldisiloxane comprising effecting the hydrolytic dehydrogenation of 1,1,3,3-tetramethyldisiloxane in the presence of water and a transition metal catalyst from Group VIII of the long-period form of the Periodic Table.
    Type: Application
    Filed: February 21, 2001
    Publication date: October 18, 2001
    Inventor: Tadashi Okawa
  • Publication number: 20010012881
    Abstract: A curable organosiloxane composition comprising: (A) an organopolysiloxane having at least two silicon atom-bonded alkenyl groups per molecule; (B) an organopolysiloxane having at least two silicon atom-bonded hydrogen atoms per molecule; (C) a compound having an alkenyl group and a phenol residue of the formula: 1
    Type: Application
    Filed: March 15, 2001
    Publication date: August 9, 2001
    Inventors: Masaaki Amako, Tadashi Okawa
  • Publication number: 20010011120
    Abstract: A process for the production of a cyclic siloxane described by formula
    Type: Application
    Filed: January 19, 2001
    Publication date: August 2, 2001
    Inventors: Tadashi Okawa, Junichi Maeshima, Norkatsu Higuchi, Takao Takemasa
  • Patent number: 6265516
    Abstract: An anti-staining additive comprising a higher unsaturated aliphatic acid ester-modified organosilicon compound that is produced by carrying out an addition reaction between (a) a higher unsaturated aliphatic acid ester that contains more than one aliphatically unsaturated bond in each molecule  and (b) an organosilicon compounds that contains at least 1 silicon-bonded hydrogen atom in each molecule with the aliphatically unsaturated bonds in component (a) present in molar excess over the silicon-bonded hydrogen in component (b). The additive can be used at 0.01 to 50 weight percent in a polyorganosiloxane composition that cures at room temperature by a condensation reaction.
    Type: Grant
    Filed: February 18, 2000
    Date of Patent: July 24, 2001
    Assignee: Dow Corning Toray Silicone Company, Ltd.
    Inventors: Tadashi Okawa, Wataru Nishiumi, Seiji Hori
  • Patent number: 6252029
    Abstract: This invention relates to a hydroxyphenyl group-containing organosilicon compound of the formula: where X is an alkenyl group; Z is a phenylene group or a carbonyloxy group expressed by —C(O)O-1, Y is a substituted or unsubstituted hydroxyphenyl group, R1 is a hydrocarbon group with two or more carbon atoms, with the various groups being the same or different, R is a monovalent hydrocarbon group containing no aliphatic unsaturated bonds, A is a divalent hydrocarbon group with one or more carbon atoms or a group expressed by the formula —R2—O—R2— where R2 is a divalent hydrocarbon group, m and p are 0 or 1, n is a number from 0 to 2, and q is an integer from 0 to 7. These compounds are useful in curable organosiloxane compositions.
    Type: Grant
    Filed: September 30, 1999
    Date of Patent: June 26, 2001
    Assignee: Dow Corning Toray Silicone Co. Ltd.
    Inventors: Masaaki Amako, Tadashi Okawa
  • Patent number: 6197988
    Abstract: A method for purifying 3-methacryloxypropyldimethylhalosilanes or 3-methacryloxypropylmethyldihalosilanes which is characterized by the fact that 1-methyl-2-methacryloxyethyldimethylhalosilanes or 1-methyl-2-methacryloxyethylmethyldihalosilanes contained in products or fractions consisting of 3-methacryloxypropyldimethylhalosilanes or 3-methacryloxypropylmethyldihalosilanes produced by a hydrosilation reaction of allyl methacrylate with dimethylhalosilanes or methyldihalosilanes are decomposed by means of a metal halide which shows the properties of a Lewis acid, after which these compounds are subjected to fractional distillation.
    Type: Grant
    Filed: December 1, 1997
    Date of Patent: March 6, 2001
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventors: Tadashi Okawa, Ryuzo Mikami
  • Patent number: 6172252
    Abstract: wherein A is hydrogen or a residue afforded by the removal of n hydroxyl groups from an m-valent alcohol, each R is independently a monovalent hydrocarbon group free of aliphatic unsaturation, each R1 is independently a divalent hydrocarbon group containing at least 2 carbon atoms, m and n are natural numbers wherein m≧n, p is 0 or 1, and Y is a phenol group having the formula: wherein R3 is alkyl and q is from 0 to 4. Also, a method of preparing a phenol-functional organosilicon compound.
    Type: Grant
    Filed: March 21, 2000
    Date of Patent: January 9, 2001
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventors: Masaaki Amako, Tadashi Okawa
  • Patent number: 6156437
    Abstract: A curable composition, comprising a siloxane grafted vinyl polymer as its main component, reacts with an organic silicon compound having silicon-bonded hydrogen atoms in the presence of a hydrosilylation catalyst to form a peelable cured coating film. The siloxane grafted vinyl polymer has two unique grafted siloxane chains represented by the following general formulae (A) and (B): ##STR1## where R.sup.1 is a divalent organic group, R.sup.2 is a monovalent hydrocarbon group which is free of aliphatic bonds, R.sup.3 is a monovalent hydrocarbon group, Y is a monovalent organic group having unsaturated aliphatic bonds, a is 0 or 1, m is an integer between 0 and 20, n is an integer which is I or greater, and p is an integer of 1, 2 or 3.
    Type: Grant
    Filed: February 25, 1999
    Date of Patent: December 5, 2000
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventors: Ryuko Manzoji, Tadashi Okawa, Ryuzo Mikami
  • Patent number: 6140525
    Abstract: This invention relates to a macromonomer and a method for its preparation. The macromonomer has silicon-bonded hydrogen atoms at one molecular chain terminal, and aliphatically unsaturated silicon-bonded organic groups at the other molecular chain terminal. This invention further related to a method of forming a hyperbranched polymer by polymerizing the macromonomer with a group VIII metal catalyst. The hyperbranched polymers can be used as surfactants, gelling agents, drug delivery systems, and polymeric absorbents.
    Type: Grant
    Filed: December 21, 1998
    Date of Patent: October 31, 2000
    Assignees: Russian Academy of Sciences, Dow Corning Corporation, Dow Corning Toray Silicone Co.
    Inventors: Tadashi Okawa, Aziz Muzafarov, Stephen Cray
  • Patent number: 6136521
    Abstract: A polycarbonate containing repeating units (1) represented by the general formula (1), a polycarbonate molding produced by molding the polycarbonate, and an electrophotographic photoreceptor having a photosensitive layer which has a surface layer containing the polycarbonate: ##STR1## wherein R is an aliphatic unsaturation-free monovalent hydrocarbon group, R.sup.1 is a halogen atom, an alkyl group, an alkoxy group or an aryl group, X is an alkylene group or an alkyleneoxyalkylene group, X' is an alkylene group of 2 or more carbon atoms, an alkyleneoxyalkylene group or oxygen atom, a is an integer of 0 to 4, na is 0 or 1, nb is 1 or 2, nc is 1 or 2, provided na+nb+nc=3, n1, n2, n3 and n4 are 0 or an integer of 1 or more, provided n1+n2+n3+n4 is an integer of 0 to 450.
    Type: Grant
    Filed: October 20, 1998
    Date of Patent: October 24, 2000
    Assignees: Idemitsu Kosan Co., Ltd., Dow Corning Toray Silicone Co., Ltd.
    Inventors: Takaaki Hikosaka, Yasuaki Horikawa, Shuji Sakamoto, Haruhiko Furukawa, Tadashi Okawa, Hiroshi Ueki, Yoshitsugu Morita, Ryuko Manzoji
  • Patent number: 6133394
    Abstract: A method for preparaing of an organofunctional organopentasiloxane which finds utility as a modifier for organic resins is disclosed, said method comprising:(I) reacting(A) a cyclotrisiloxane and(B) an .alpha.,.omega.-dihydrogendiorganodisiloxane in the presence of an(C) acid catalystto prepare an .alpha.,.omega.-dihydrogendiorganopentasiloxane having the formulaR.sub.2 HSiO(R.sub.2 SiO).sub.3 SiHR.sub.2wherein R independently represents a monovalent group free of aliphatic unsaturation selected from hydrocarbon or halogenated hydrocarbon groups; and(II) running an addition reaction in the presence of (D) a hydrosilylation catalyst between said .alpha.,.omega.-dihydrogendiorganopentasiloxane and (E) an organic compound containing a monovalent group selected from epoxy or phenol groups as well as an unsaturated aliphatic hydrocarbon group. In a variation of the method, the .alpha.,.omega.
    Type: Grant
    Filed: January 26, 1999
    Date of Patent: October 17, 2000
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventors: Haruhiko Furukawa, Tadashi Okawa, Hiroshi Ueki, Yoshitsugu Morita
  • Patent number: 6072013
    Abstract: There is disclosed a silicone-grafted vinyl polymer and a method for the preparation thereof, said polymer having grafted silicone side chains of the formula: ##STR1## as well as grafted silicone side chains of the formula: ##STR2## wherein R independently represents a monovalent hydrocarbon group which is free of aliphatic unsaturation, R.sup.1 is a divalent group selected from hydrocarbon groups or alkyleneoxyalkylene groups, a is 0 or 1 and n is an integer having a value of at least 1.
    Type: Grant
    Filed: November 24, 1998
    Date of Patent: June 6, 2000
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventors: Ryuko Manzouji, Tadashi Okawa, Ryuzo Mikami
  • Patent number: 6063887
    Abstract: A 1-acyloxy-organotetrasiloxane represented by the general formula: ##STR1## wherein R.sup.1 is a monovalent organic group containing an acryloyloxy group or a monovalent organic group containing a methacryloyloxy group, and R.sup.2 is a monovalent hydrocarbon group, and a process for producing the above mentioned 1-acyloxy-organotetrasiloxane, which is characterized by subjecting hexamethylcyclotrisiloxane to a ring-opening reaction with an acyloxysilane represented by the general formula: ##STR2## wherein R.sup.1 is a monovalent organic group containing an acryloyloxy group or a monovalent organic group containing a methacryloyloxy group, and R.sup.2 is a monovalent hydrocarbon group, in the presence of an acidic catalyst.
    Type: Grant
    Filed: May 18, 1998
    Date of Patent: May 16, 2000
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventor: Tadashi Okawa
  • Patent number: 6013822
    Abstract: A method for preparing high-purity methacryloxypropyidimethylchlorosilane is disclosed, said method comprising mixing (A) a methacryloxypropyldimethylchlorosilane which contains an Si-bonded methacryloxy-functional organosilicon compound as an impurity with (B) an inorganic chloride, reacting said inorganic chloride with said Si-bonded methacryloxy- functional organosilicon compound and thereafter isolating the methacryloxypropyldimethylchlorosilane.
    Type: Grant
    Filed: October 21, 1996
    Date of Patent: January 11, 2000
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventor: Tadashi Okawa
  • Patent number: 5939507
    Abstract: A method for manufacturing a siloxane compound described by formula R.sup.1.sub.m Si{OSi(CH.sub.3).sub.2 H}.sub.(4-m) comprising reacting a silane compound or condensation product of a silane compound described by formula R.sup.1.sub.m Si(OR.sup.2).sub.(4-m), where R.sup.1 is selected from the group consisting of hydrogen and substituted or unsubstituted monovalent hydrocarbon groups, R.sup.2 is hydrogen, alkyl groups and alkoxyalkyl groups, and m is an integer from 0 to 3, with 1,1,3,3-tetramethyldisiloxane in an aqueous solution of an acid in which the acid concentration is 1.0 wt % or less, and the molar ratio of the aqueous solution to the 1,1,3,3-tetramethyldisiloxane is in the range of 0.5 to 1.5. The method is particularly useful for manufacturing siloxane compounds having dimethylhydrodosiloxy groups.
    Type: Grant
    Filed: April 20, 1998
    Date of Patent: August 17, 1999
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventor: Tadashi Okawa
  • Patent number: 5914418
    Abstract: A method for inhibiting polymerization of acrylic-functional silanes comprising forming a mixture comprising an acrylic-functional silane and a polymerization inhibitor described by formula ##STR1## where n is 0 or 1; M is an atom selected from a group consisting of N, P, As, Sb, O, S, Se, Sn, and I; R is an independently selected monovalent hydrocarbon group or hydrogen atom; m is 1, 2, or 3; and X is a conjugate base of an organic acid or inorganic acid.
    Type: Grant
    Filed: April 15, 1997
    Date of Patent: June 22, 1999
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventors: Ryuzo Mikami, Tadashi Okawa
  • Patent number: 5912371
    Abstract: A method for preparing fatty acid chlorides. The method comprises reacting a silylation product of a fatty acid comprising at 1east 2 aliphatically unsaturated bonds per molecule and a chlorinating agent.
    Type: Grant
    Filed: October 27, 1997
    Date of Patent: June 15, 1999
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventors: Koji Nakanishi, Tadashi Okawa
  • Patent number: 5874602
    Abstract: A process for preparing a compound having the formula ##STR1## is disclosed, said process comprising hydrolyzing an organosilicon compound of the formula ##STR2## wherein X is a radically polymerizable group-functional organic group, R.sup.1 is independently selected from monovalent hydrocarbon groups that are free of aliphatic unsaturation, R.sup.2 is independently selected from the group consisting of hydrogen and a monovalent hydrocarbon group and m is an integer having a value of 1 to 3.
    Type: Grant
    Filed: March 27, 1998
    Date of Patent: February 23, 1999
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventors: Ryuko Manzouji, Tadashi Okawa
  • Patent number: 5856545
    Abstract: A process for the production of organopentasiloxane represented by the general formula: ##STR1## wherein R.sup.1 is an acryloyloxy-containing monovalent organic group or a methacryloyloxy-containing monovalent organic group; R.sup.3 is a monovalent hydrocarbon group; X is a hydrolytic group; and the subscript n is 0, 1, or 2; which is characterized subjecting (A) 1-hydroxy-organotetrasiloxane, or an organosiloxane oligomer mixture comprising it as the main component, which is obtained by hydrolyzing 1-acyloxy-organotetrasiloxane or an oganosiloxane oligomer mixture comprising it as the main component; and (B) hydrolytic silane represented by the general formula R.sup.3.sub.n SiX.sub.(4-n) to a condensation reaction.
    Type: Grant
    Filed: December 5, 1997
    Date of Patent: January 5, 1999
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventor: Tadashi Okawa
  • Patent number: 5847178
    Abstract: A method for purifying 3-methacryloxypropyldimethylhalosilanes or 3-methacryloxypropyl methyldihalosilanes which is characterized by the fact that 1-methyl-2-methacryloxyethyldimethyl halosilanes or 1-methyl-2-methacryloxyethylmethyldihalosilanes contained in products or fractions consisting of 3-methacryloxypropyldimethylhalosilanes or 3-methacryloxypropylmethyl dihalosilanes produced by a hydrosilation reaction of allyl methacrylate with dimethylhalosilanes or methyldihalosilanes are decomposed by means of at least one copper compound selected from the group consisting of copper hydroxides, copper salts other than copper halides, and copper oxides, after which these compounds are subjected to fractional distillation.
    Type: Grant
    Filed: December 2, 1997
    Date of Patent: December 8, 1998
    Assignee: Dow Corning Toray Silicone Co., Ltd.
    Inventor: Tadashi Okawa