Patents by Inventor Ambelal R. Patel

Ambelal R. Patel 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: 5578731
    Abstract: An asymmetrical hydrazine derivative of formula V ##STR1## where R.sub.1 is alkoxy of 1 to 18 carbon atoms or cycloalkyl of 5 to 12 carbon atoms;X is --O-- or --NR.sub.2 -- where R.sub.2 is hydrogen, alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, alkyl of 2 to 4 carbon atoms substituted by one alkoxy group of 1 to 12 carbon atoms or a group of formula II ##STR2## in which R.sub.1 is as defined above; and E is a alkyl of 1 to 20 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, aryl of 6 to 14 carbon atoms or phenylalkyl of 7 to 22 carbon atoms, orE is --CONHR.sub.4, --CSNHR.sub.5, --COR.sub.6 COR.sub.7, --COR.sub.8 CONHR.sub.9, --COR.sub.10, --COOR.sub.11 or --SO.sub.2 R.sub.12,in which R.sub.4, R.sub.5, R.sub.7, R.sub.9, R.sub.10, R.sub.11 and R.sub.12 are each independently of the other hydrogen, alkyl of 1 to 20 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, aryl of 6 to 14 carbon atoms or phenylalkyl of 7 to 22 carbon atoms; andR.sub.6 and R.sub.
    Type: Grant
    Filed: June 5, 1995
    Date of Patent: November 26, 1996
    Assignee: Ciba-Geigy Corporation
    Inventors: Ramanathan Ravichandran, Ambelal R. Patel
  • Patent number: 5554754
    Abstract: New azodicarboxylic acid derivatives of formula I ##STR1## where R.sub.1 is hydrogen, oxyl, hydroxyl, alkyl, allyl, benzyl, alkoxy or acyl, and X is --O-- or --NR-- where R is hydrogen or alkyl, are useful for the stabilization of polymers, particularly unsaturated elastomers, by being grafted thereon.
    Type: Grant
    Filed: June 5, 1995
    Date of Patent: September 10, 1996
    Assignee: Ciba-Geigy Corporation
    Inventors: Ramanathan Ravichandran, Ambelal R. Patel
  • Patent number: 5470980
    Abstract: The instant invention relates to novel hydrazine derivatives of formula III ##STR1## where R.sub.1 is hydrogen, oxyl, hydroxyl, alkyl, of 2 to 4 carbon atoms substituted by one hydroxyl group, allyl, benzyl, benzyl substituted by one of two alkyl of 1 to 4 carbon atoms or alkanoyl of 1 to 8 carbon atoms, and X is --O-- or --NR.sub.2 -- where R.sub.2 is hydrogen or alkyl. These compounds are useful as intermediates from which to prepare the corresponding azo compounds, which are useful for the stabilization of polymers, particularly unsaturated elastomers, by being grafted thereon.
    Type: Grant
    Filed: September 30, 1994
    Date of Patent: November 28, 1995
    Assignee: Ciba-Geigy Corporation
    Inventors: Ramanathan Ravichandran, Ambelal R. Patel
  • Patent number: 5380828
    Abstract: New azodicarboxylic acid derivatives of formula I ##STR1## where R.sub.1 is hydrogen, oxyl, hydroxyl, alkyl, allyl, benzyl, alkoxy or acyl, and X is --O-- or --NR-- where R is hydrogen or alkyl, are useful for the stabilization of polymers, particularly unsaturated elastomers, by being grafted thereon.
    Type: Grant
    Filed: April 7, 1994
    Date of Patent: January 10, 1995
    Assignee: Ciba-Geigy Corporation
    Inventors: Ramanathan Ravichandran, Ambelal R. Patel
  • Patent number: 5240976
    Abstract: Elastomers are very effectively stabilized against thermal and oxidative degradation at elevated temperatures with a blend of an N,N,N',N'-tetrasubstituted 1,4-diamino-2-butene, where the substituents are alkyl, cycloalkyl, aralkyl, aryl or mixtures thereof, in combination with a mercaptoimidazole of formula IV ##STR1## where E is hydrogen, alkyl, cycloalkyl, aryl or phenylalkyl.
    Type: Grant
    Filed: August 21, 1992
    Date of Patent: August 31, 1993
    Assignee: Ciba-Geigy Corporation
    Inventors: Douglas W. Horsey, Ambelal R. Patel
  • Patent number: 5149774
    Abstract: Polyolefins, especially those containing a phenolic antioxidant, are prone to discoloration upon improper processing at elevated temperatures or upon prolonged aging. Such discolored polyolefins can be reclaimed and recycled as essentially non-colored useful polymers by the addition thereto of a hydroxylamine of the formulaT.sub.1 T.sub.2 NOHwhere T.sub.1 and T.sub.2 are independently alkyl, cycloalkyl, benzyl or substituted benzyl.
    Type: Grant
    Filed: July 31, 1990
    Date of Patent: September 22, 1992
    Assignee: Ciba-Geigy Corporation
    Inventors: Ambelal R. Patel, Stephen D. Pastor
  • Patent number: 5128397
    Abstract: Hot melt adhesive compositions stabilized against thermal degradation, discoloration, skin formation and substantial viscosity changes, said adhesives being based on ethylene-vinyl acetate copolymer and a hydrocarbon tackifying resin and containing a stabilizer system of a hindered phenol antioxidant, a phosphite costabilizer and an acid scavenger.
    Type: Grant
    Filed: May 9, 1991
    Date of Patent: July 7, 1992
    Assignee: Ciba-Geigy Corporation
    Inventors: Douglas W. Horsey, Ambelal R. Patel
  • Patent number: 5096950
    Abstract: Hindered amines based on various 2,2,6,6-tetraalkylated nitrogen-containing heterocyclic moieties wherein the hindered nitrogen atom on the ring is substituted with OR.sub.1 substituents and the 4-position of the ring is substituted with a diversity of substituents are effective in protecting polyolefins against the adverse effects of light, heat and oxygen.
    Type: Grant
    Filed: August 6, 1990
    Date of Patent: March 17, 1992
    Assignee: Ciba-Geigy Corporation
    Inventors: James P. Galbo, Raymond Seltzer, Ramanathan Ravichandran, Ambelal R. Patel
  • Patent number: 5004770
    Abstract: Hindered amines based on various 2,2,6,6-tetralkylated nitrogen-containing heterocyclic moieties wherein the hindered nitrogen atom on the ring is substituted with OH or OR substituents and the 4-position of the ring is substituted with a diversity of substituents are effective in protecting a variety of non-polyolefin substrates against the adverse effects of light, heat and oxygen.
    Type: Grant
    Filed: October 3, 1989
    Date of Patent: April 2, 1991
    Assignee: Ciba-Geigy Corporation
    Inventors: Frank P. Cortolano, Raymond Seltzer, Ambelal R. Patel
  • Patent number: 4898901
    Abstract: Long chain N-alkyl-alpha-alkyl nitrones represent particularly valuable process stabilizers for polyolefin compositions. The nitrone derived from the long chain alkyl mixture present in di(hydrogenated tallow)amine is especially useful for this purpose.
    Type: Grant
    Filed: March 23, 1989
    Date of Patent: February 6, 1990
    Assignee: Ciba-Geigy Corporation
    Inventors: Ramanathan Ravichandran, Stephen D. Pastor, Raymond Seltzer, Ambelal R. Patel
  • Patent number: 4876300
    Abstract: Long chain N,N-dialkylhydroxylamines represent particularly valuable process stabilizers for polyolefin compositions. The hydroxylamine derived from di(hydrogenated tallow)amine is particularly useful for this purpose. These long chain N,N-dialkylhydroxylamines are very resistant to extraction from polyolefin compositions.
    Type: Grant
    Filed: December 30, 1987
    Date of Patent: October 24, 1989
    Assignee: Ciba-Geigy Corporation
    Inventors: Raymond Seltzer, Ramanathan Ravichandran, Ambelal R. Patel
  • Patent number: 4782105
    Abstract: Long chain N,N-dialkylhydroxylamines represent particularly valuable stabilizers for a number of polymer substrates. Their particular value is seen in their high temperature processing stabilization of poly(arylene sulfide), such as poly(phenylene sulfide), PPS, and of selected unsaturated elastomers used to modify thermoplastics. PPS is processed at elevated temperatures (300.degree. to 425.degree. C.) at which temperatures it crosslinks readily. Process stabilizers can extend the time to crosslinking and hence the processibility of the PPS. Long chain N,N-dialkylhydroxylamines are very effective process stabilizers for PPS being far superior to phenolic antioxidants, phosphites or amines. The hydroxylamine derived from di(hydrogenated tallow)amine is particularly useful for this purpose.
    Type: Grant
    Filed: April 10, 1987
    Date of Patent: November 1, 1988
    Assignee: Ciba-Geigy Corporation
    Inventors: Ramanathan Ravichandran, Ambelal R. Patel, Frank P. Cortolano, Richard W. Thomas
  • Patent number: 4668721
    Abstract: N,N-Dibenzylhydroxylamine and other selected hydroxylamine derivatives are effective in stabilizing polyolefin compositions containing a stabilizer or mixture of stabilizers selected from the group consisting of the phenolic antioxidants, the hindered amine light stabilizers, the ultraviolet light absorbers, the organic phosphorus compounds, the alkaline metal salts of fatty acids and the thiosynergists, against degradation upon high temperature extrusion, exposure to the combustion products of natural gas, gamma irradiation or upon storage for extended periods.
    Type: Grant
    Filed: February 3, 1986
    Date of Patent: May 26, 1987
    Assignee: Ciba-Geigy Corporation
    Inventors: Raymond Seltzer, Ambelal R. Patel, Peter W. Stewart, Charlene White
  • Patent number: 4590231
    Abstract: N,N-Dibenzylhydroxylamine and other selected hydroxylamine derivatives are effective in stabilizing polyolefin compositions containing a stabilizer or mixture of stabilizers selected from the group consisting of the phenolic antioxidants, the hindered amine light stabilizers, the ultraviolet light absorbers, the organic phosphorus compounds, the alkaline metal salts of fatty acids and the thiosynergists, against degradation upon high temperature extrusion, exposure to the combustion products of natural gas, gamma irradiation or upon storage for extended periods.
    Type: Grant
    Filed: July 23, 1984
    Date of Patent: May 20, 1986
    Assignee: Ciba-Geigy Corporation
    Inventors: Raymond Seltzer, Ambelal R. Patel, Peter W. Stewart, Charlene White