Patents by Inventor Sivaram Krishnan

Sivaram Krishnan 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).

  • Patent number: 4828921
    Abstract: A moulding composition comprising a polycarbonate resin and an acrylate-based plating modifier was found to be suitable for preparing metal coated articles where the metal coating is deposited by an electroless process. In a preferred embodiment of the invention the moulding composition further comprise a flame retarding agent.
    Type: Grant
    Filed: November 17, 1987
    Date of Patent: May 9, 1989
    Assignee: Mobay Corporation
    Inventors: Mark W. Witman, Sivaram Krishnan, Wolfgang Siebourg, Ronald L. Price
  • Patent number: 4816504
    Abstract: Polycarbonate compositions comprising a small amount of a certain halogenobenzotriazole were found to be particularly suitable for optical purposes since they feature a desirable high UV-cutoff and since they are processable at high temperatures.
    Type: Grant
    Filed: October 13, 1987
    Date of Patent: March 28, 1989
    Assignee: Mobay Corporation
    Inventors: John V. Bailey, Sivaram Krishnan
  • Patent number: 4804692
    Abstract: The invention relates to thermoplastic polycarbonate molding compositions which are rendered resistant to gamma-radiation by incorporating therewith about 0.05 to about 10 percent by weight of a stabilizing agent selected from the group consisting of ##STR1## wherein R is a hydrogen or a halogen atom or a C.sub.1 -C.sub.10 alkyl, a C.sub.6 -C.sub.10 aryl, C.sub.1 -C.sub.22 acyl, C.sub.6 -C.sub.18 alkylaryl or a C.sub.4 -C.sub.10 cycloalkyl radical, m is 1 or 3 to 6, n is an integer of about 20 to 70 and Y is a radical conforming to ##STR2## wherein R, R' and R" independently one of the others are selected from C.sub.1 -C.sub.10 alkyl and C.sub.6 -C.sub.12 aryl radicals preferably C.sub.1 -C.sub.4 alkyl radical.
    Type: Grant
    Filed: April 28, 1988
    Date of Patent: February 14, 1989
    Assignee: Mobay Corporation
    Inventors: Charles E. Lundy, Winfried G. Paul, Sivaram Krishnan
  • Patent number: 4772655
    Abstract: The present invention is directed to flame retardant, pigmented polycarbonate molding compositions which properties include both good flame resistance properties and virtual freedom from streaking. The compositions are particularly suitable for use in molding machines using hot runner tools. The composition of the invention comprise a thermoplastic aromatic polycarbonate resin, a flame retarding agent, pigments, polytetrafluoroethylene--ASTM Type 3--and an amount of finely divided hydrophobic silicon dioxide sufficient for providing streaking-free molded articles.
    Type: Grant
    Filed: June 1, 1987
    Date of Patent: September 20, 1988
    Assignee: Mobay Corporation
    Inventors: Sivaram Krishnan, Roger J. White, Ronald L. Price
  • Patent number: 4753994
    Abstract: The present invention is related to polycarbonate molding compositions containing a co-precipitate of a polycarbonate resin and a fluoropolymer. This co-precipitate was found to be suitable as an additive for polycarbonate resins because it offers improved dispersibility with the resin and good flammability performance as well as aesthetic characteristics. The co-precipitate is prepared by first mixing an aqueous dispersion of a fluoropolymer with a polycarbonate solution and then precipitating both using a suitable precipitation agent. After isolation washing and drying the co-precipitate of the invention is suitable for incorporation in a polycarbonate resin optionally with known flame retarding agents. Molded parts prepared from the compositions of the invention are characterized by their improved homogeneity and flame retardance.
    Type: Grant
    Filed: December 2, 1986
    Date of Patent: June 28, 1988
    Assignees: Mobay Corporation, Bayer Aktiengesellschaft
    Inventors: Russell P. Carter, Jr., Ulrich Grigo, Sivaram Krishnan, Mark W. Witman, Klaus Kircher, Hans-Jurgen Kress, Wolfgang Alewelt
  • Patent number: 4751250
    Abstract: The present invention relates to an improvement in preparing foamed thermoplastic articles. It was found that a chemical blowing agent concentrate which contains a blowing agent which produces primary amines upon decomposition and additionally contains an anhydride compound which contains at least one cyclic anhydride in its structure, offers surprising advantages over the prior art process in terms of improved impact strength and process flexibility.
    Type: Grant
    Filed: May 14, 1986
    Date of Patent: June 14, 1988
    Assignee: Mobay Corporation
    Inventors: Roger J. White, Sivaram Krishnan
  • Patent number: 4737523
    Abstract: Foamable, thermoplastic molding composition exhibiting an improved level of impact resistance is provided. The composition, which is suitable for the preparation of expanded molded parts, comprise a thermoplastic resin, preferably at least one selected from a group consisting of polycarbonate, polyalkylene terephthalate, aromatic polyester and polyester carbonate, a nucleating agent, a chemical blowing agent and an anhydride. It was unexpectedly found that the composition is suitable for the molding of articles having an improved level of impact resistance.
    Type: Grant
    Filed: June 19, 1987
    Date of Patent: April 12, 1988
    Assignee: Mobay Corporation
    Inventors: Roger J. White, Sivaram Krishnan, Wolfgang J. Siebourg
  • Patent number: 4673699
    Abstract: Novel molding compositions comprising a polycarbonate resin and the halogenated reaction product of phthalic anhydride and aniline are characterized in their improved flame resistance and are useful for the preparation of molded articles.
    Type: Grant
    Filed: November 19, 1984
    Date of Patent: June 16, 1987
    Assignee: Mobay Corporation
    Inventors: Sivaram Krishnan, Ulrich R. Grigo
  • Patent number: 4650823
    Abstract: The present invention is directed to a thermoplastic molding composition comprising a polycarbonate resin and a pigmenting amount of black iron oxide. The invention is predicated on the surprising findings that this composition yields stable, streaking-free molded articles. A preferred embodiment of the invention comprises a flame retarding agent and iron oxide based pigment selected from the group consisting of black iron oxide and red iron oxide, said flame retarding agent comprising polytetrafluoroethylene; the composition is characterized in that it is streaking-free and in that its flammability rating is at least 5V-1/8" in accordance with UL-94.
    Type: Grant
    Filed: August 16, 1985
    Date of Patent: March 17, 1987
    Assignee: Mobay Corporation
    Inventors: Sivaram Krishnan, Ronald L. Price, Roger J. White
  • Patent number: 4632949
    Abstract: The present invention relates to novel N-(alkoxyphenyl) phthalimides conforming to the structure ##STR1## wherein X is a halogen atom, R is a C.sub.1 -C.sub.4 alkyl, g is 1 to 5, n is an integer of from 0 to 4, m is either 0 or 1 and p is either 0 or 1. The phthalimide thus disclosed was found to be suitable as a flame retarding additive for thermoplastic molding compositions, especially compositions comprising polycarbonate resins.
    Type: Grant
    Filed: December 31, 1984
    Date of Patent: December 30, 1986
    Assignee: Mobay Chemical Corporation
    Inventor: Sivaram Krishnan
  • Patent number: 4594375
    Abstract: The present invention relates to novel bis-(imide-sulphonates) of the formula (I), a process for their preparation, their use for flameproofing aromatic, thermoplastic polycarbonates obtained from halogen-free diphenols, and thermoplastic aromatic polycarbonates obtained from halogen-free diphenols and containing 0.01 to 1% by weight, of bis-(imide-sulphonate) of the formula (I), based on an aromatic, thermoplastic polycarbonate.
    Type: Grant
    Filed: June 4, 1984
    Date of Patent: June 10, 1986
    Assignee: Bayer Aktiengesellschaft
    Inventors: Sivaram Krishnan, Klaus Kircher, Hans-Jurgen Kress
  • Patent number: 4578409
    Abstract: The present invention relates to a novel halogenated silane conforming to the structure ##STR1## where X is a halogen atom, n is an integer of from 1 to 4, p is an integer of from 1 to 9 and m is an integer of from 1 to 5. The silane thus disclosed was found to be particularly suitable as a flame retarding additive for thermoplastic molding compositions.
    Type: Grant
    Filed: January 14, 1985
    Date of Patent: March 25, 1986
    Assignee: Mobay Chemical Corporation
    Inventors: Sivaram Krishnan, Ulrich R. Grigo, Donald A. Folajtar
  • Patent number: 4558162
    Abstract: The present invention relates to the novel monomer 4,4'-bis(4-hydroxyphenyl thio)biphenyl, to a process for its production and to its use in the preparation of polycarbonates, polyurethanes, polyesters, polysulfones and polyethers.
    Type: Grant
    Filed: May 7, 1984
    Date of Patent: December 10, 1985
    Assignee: Mobay Chemical Corporation
    Inventors: Sivaram Krishnan, John R. Sanderson
  • Patent number: 4552911
    Abstract: The present invention relates to polycarbonate molding compositions containing additives of alkali or alkaline earth metal salts, tetrahalogenophthalimides and optional glass fibers, characterized in that they contain additive amounts of bromine.
    Type: Grant
    Filed: January 28, 1983
    Date of Patent: November 12, 1985
    Assignee: Bayer Aktiengesellschaft
    Inventors: Wolfgang Cohnen, Klaus Kircher, Peter R. Muller, Sivaram Krishnan, Dieter Neuray
  • Patent number: 4539384
    Abstract: The present invention relates to the novel monomer 4,4'-bis(4-hydroxyphenyl thio)biphenyl, to a process for its production and to its use in the preparation of polycarbonates, polyurethanes, polyesters, polysulfones and polyethers.
    Type: Grant
    Filed: May 7, 1984
    Date of Patent: September 3, 1985
    Assignee: Mobay Chemical Corporation
    Inventors: Sivaram Krishnan, John R. Sanderson
  • Patent number: 4535143
    Abstract: The present invention is directed to a continuous process for the preparation of copolycarbonates of sulfonyl diphenol (SDP) containing at least about 15, preferably about 15 to about 80 percent by weight of SDP and characterized in the particular system catalyzing the process reaction. The invention thus entails improvements and modifications to the known interfacial polycondensation process rendering it applicable to the preparation of copolycarbonates containing a high level of SDP comprising a combination of catalysts namely a phase transfer catalyst and a condensation catalyst.
    Type: Grant
    Filed: August 6, 1984
    Date of Patent: August 13, 1985
    Assignee: Mobay Chemical Corporation
    Inventors: Ronald L. Price, Mark W. Witman, Sivaram Krishnan
  • Patent number: 4515937
    Abstract: The invention relates to an aromatic, high molecular weight thermoplastic copolycarbonate comprising the reaction product of a sulfur-free aromatic diphenol, a sulfur-containing diphenol, a branching agent and a carbonic acid derivative, characterized in having improved flame resistance. The invention further relates to a process for the preparation of said copolycarbonate.
    Type: Grant
    Filed: September 9, 1980
    Date of Patent: May 7, 1985
    Assignee: Mobay Chemical Corporation
    Inventors: Arthur L. Baron, Sivaram Krishnan
  • Patent number: 4503213
    Abstract: The instant invention relates to a process for the preparation of linear aromatic polycarbonate resins by the known two-phase interfacial process and is directed to the use of perfluoroalkyl sulfonamides as chain stoppers in said process and is further directed to the polycarbonate resins obtainable by the process which resins are suitable in the preparation of thermoplastic molding compositions.
    Type: Grant
    Filed: June 21, 1983
    Date of Patent: March 5, 1985
    Assignee: Bayer Aktiengesellschaft
    Inventors: Sivaram Krishnan, Dieter Neuray, Wolfgang Cohnen, Klaus Geisler
  • Patent number: 4497947
    Abstract: The present invention is directed to an aromatic copolycarbonate molding composition comprising the reaction product of an aromatic diphenol, an aromatic sulfonyl diphenol, a dihydroxybiphenyl and a carbonic acid derivative, said composition being characterized by its improved heat deflection temperature and critical thickness.
    Type: Grant
    Filed: December 5, 1983
    Date of Patent: February 5, 1985
    Assignee: Mobay Chemical Corporation
    Inventors: John R. Sanderson, Sivaram Krishnan
  • Patent number: 4477637
    Abstract: A flame resistant polycarbonate blend comprising an alkylated aromatic polycarbonate and a sulfur-bearing compound characterized in exhibiting V-0 flame resistance classification, according to UL-94, is provided. Further provided is a process for the preparation of such blend.
    Type: Grant
    Filed: August 27, 1980
    Date of Patent: October 16, 1984
    Assignee: Mobay Chemical Corporation
    Inventor: Sivaram Krishnan