Patents by Inventor David G. Leppard

David G. Leppard 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: 5261953
    Abstract: Inks, in particular for ink-jet printing, containing, as stabilizer, a water-soluble compound of the formula ##STR1## in which R.sub.1 to R.sub.7 are as defined in claim 1, and recording materials containing these compounds.
    Type: Grant
    Filed: November 20, 1991
    Date of Patent: November 16, 1993
    Assignee: Ciba-Geigy Corporation
    Inventors: Eric Vieira, David G. Leppard, Hugh S. Laver, Vien V. Toan
  • Patent number: 5202458
    Abstract: Compounds of the formula I or II ##STR1## in which R, R.sup.0, R.sup.1 and R.sup.2 are as defined in claim 1. The compounds, some of which are novel, are light stabilizers for color photographic recording materials.
    Type: Grant
    Filed: August 5, 1991
    Date of Patent: April 13, 1993
    Assignee: Ciba-Geigy AG
    Inventor: David G. Leppard
  • Patent number: 5169950
    Abstract: Compounds of the formula I ##STR1## wherein R, R.sup.1, R.sup.2, R.sup.3, and R.sup.5 have the meaning given in claim 1 are formed by thermal rearrangement of the isomers of formula V ##STR2## especially in the presence of basic catalysts. The compounds are corrosion inhibitors for organic materials, in particular coating materials and lubricants. In these substrates they also act as antioxidants and light-stabilizers and are very stable to heat.
    Type: Grant
    Filed: August 19, 1991
    Date of Patent: December 8, 1992
    Assignee: Ciba-Geigy Corporation
    Inventors: Adalbert Braig, Hans-Rudolf Meier, David G. Leppard, Robert C. Wasson, Emyr Phillips
  • Patent number: 5149828
    Abstract: Tetrahydrothiopyran compound of the formula I ##STR1## in which R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, X and n are as defined in claim 1, are effective stabilizers for dyes and dye couplers in photographic layers. In particular, they provide protection from damage by light. They are preferably used in combination with a phenolic antioxidant.
    Type: Grant
    Filed: March 21, 1990
    Date of Patent: September 22, 1992
    Assignee: Ciba-Geigy AG
    Inventors: Jean Rody, David G. Leppard
  • Patent number: 5145766
    Abstract: Compounds of the formula ##STR1## in which R is hydrogen or hydroxyl, R.sub.1 is alkyl, alkoxy, amino or aryl, and R.sub.2 is hydrocarbylcarbonyl or hydrocarbylsulfonyl, are highly suitable for stabilizing magenta couplers in photographic materials.
    Type: Grant
    Filed: May 13, 1991
    Date of Patent: September 8, 1992
    Assignee: Ciba-Geigy Corporation
    Inventors: David G. Leppard, David H. Steinberg, Henri Dubas
  • Patent number: 5097039
    Abstract: Compounds of the formula I ##STR1## wherein R, R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 have the meaning given in claim 1 are formed by thermal rearrangement of the isomers of formula V ##STR2## especially in the presence of basic catalysts. The compounds are corrosion inhibitors for organic materials, in particular coating materials and lubricants. In these substrates they also act as antioxidants and light-stabilizers and are very stable to heat.
    Type: Grant
    Filed: August 14, 1989
    Date of Patent: March 17, 1992
    Assignee: Ciba-Geigy Corporation
    Inventors: Adalbert Braig, Hans-Rudolf Meier, David G. Leppard, Robert C. Wasson, Emyr Phillips
  • Patent number: 5089050
    Abstract: Inks, in particular for ink-jet printing, containing, as stabilizer, a water-soluble compound of the formula ##STR1## in which R.sub.1 to R.sub.7 are as defined in claim 1, and recording materials containing these compounds.
    Type: Grant
    Filed: May 6, 1991
    Date of Patent: February 18, 1992
    Assignee: Ciba-Geigy Corporation
    Inventors: Eric Vieira, David G. Leppard, Hugh S. Laver, Vien V. Toan
  • Patent number: 5071993
    Abstract: Compounds of the formula ##STR1## in which R.sup.1 and R.sup.3 independently of one another are C.sub.1 -C.sub.8 alkyl, cyclopentyl, cyclohexyl, C.sub.7 -C.sub.9 aralkyl, phenyl or a group of the formula--C.sub.m H.sub.2m+1-q (X).sub.q (II)in which m is a number from 0-10 and q is 1 or 2, with q=1 in the case of m=0, R.sup.2 and R.sup.4 independently of one another are each a group of the formula II or, in the case that R.sup.1 and R.sup.3 are each a group of the formula II, R.sup.2 and R.sup.4 independently of one another can also be C.sub.1 -C.sub.8 alkyl, cyclopentyl, cyclohexyl, C.sub.7 -C.sub.9 aralkyl or phenyl, R.sup.5 and R.sup.6 independently of one another are hydrogen, methyl, ethyl or together are trimethylene or tetramethylene, and X is a group of the formula ##STR2## in which the general symbols are as defined in claim 1, are suitable as fluorescent brighteners especially for photographic recording materials and for synthetic polymers.
    Type: Grant
    Filed: September 12, 1989
    Date of Patent: December 10, 1991
    Assignee: Ciba-Geigy Corporation
    Inventors: David G. Leppard, Eric Vieira
  • Patent number: 5070007
    Abstract: Phenolic thiane derivatives of the formula I or II ##STR1## in which n is 0, 1 or 2 and R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10, T and Z are as defined in claim 1, are effective stabilizers for color photography recording materials, in particular for the yellow layer. They act not only as light stabilizers but also as stabilizers against thermal oxidation.
    Type: Grant
    Filed: February 6, 1991
    Date of Patent: December 3, 1991
    Assignee: Ciba-Geigy AG
    Inventors: Jean Rody, David G. Leppard
  • Patent number: 5069805
    Abstract: Compounds of the formula I ##STR1## wherein R, R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 have the meaning given in claim 1 are formed by thermal rearrangement of the isomers of formula V ##STR2## especially in the presence of basic catalysts. The compounds are corrosion inhibitors for organic materials, in particular coating materials and lubricants. In these substrates they also act as antioxidants and light-stabilizers and are very stable to heat.
    Type: Grant
    Filed: September 14, 1990
    Date of Patent: December 3, 1991
    Assignee: Ciba-Geigy Corporation
    Inventors: Adalbert Braig, Hans-Rudolf Meier, David G. Leppard, Robert C. Wasson, Emyr Phillips
  • Patent number: 5059515
    Abstract: Compounds of the formula I or II ##STR1## in which R, R.sup.0, R.sup.1 and R.sup.2 are as defined in claim 1. The compounds, some of which are novel, are light stabilizers for color photographic recording materials.
    Type: Grant
    Filed: September 28, 1990
    Date of Patent: October 22, 1991
    Assignee: Ciba-Geigy AG
    Inventor: David G. Leppard
  • Patent number: 5006665
    Abstract: Phenolic thiane derivatives of the formula I or II ##STR1## in which n is 0, 1 or 2 and R.sup.2, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10, T and Z are as defined in claim 1, are effective stabilizers for color photography recording materials, in particular for the yellow layer. They act not only as light stabilizers but also as stabilizers against thermal oxidation.
    Type: Grant
    Filed: September 29, 1988
    Date of Patent: April 9, 1991
    Assignee: Ciba-Geigy AG
    Inventors: Jean Rody, David G. Leppard
  • Patent number: 4996326
    Abstract: Benzotriazoles of the formula I ##STR1## in which R.sup.1 and R.sup.2 are located in the ortho-position or para-position relative to the OH group and at least one of these substituents in an .alpha.-branched alkyl group containing a polar group M in the .omega.-position are liquid or low-melting compounds which absorb UV light and can be used as stabilizers for organic materials. M can be, for example, an ester or amide group. R.sup.3 can be H, Cl, alkyl, alkoxy or a carboxyl group.
    Type: Grant
    Filed: January 12, 1990
    Date of Patent: February 26, 1991
    Assignee: Ciba-Geigy Corporation
    Inventors: David G. Leppard, Mario Slongo, Jean Rody
  • Patent number: 4933271
    Abstract: Tetrahydrothiopyran compound of the formula I ##STR1## in which R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, X and n are as defined in claim 1, are effective stabilizers for dyes and dye couplers in photographic layers. In particular, they provide protection from damage by light. They are preferably used in combination with a phenolic antioxidant.
    Type: Grant
    Filed: September 29, 1988
    Date of Patent: June 12, 1990
    Assignee: Ciba-Geigy AG
    Inventors: Jean Rody, David G. Leppard
  • Patent number: 4894091
    Abstract: Compounds of the formula I ##STR1## wherein R, R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 have the meaning given in claim 1 are formed by thermal rearrangement of the isomers of formula V ##STR2## especially in the presence of basic catalysts. The compounds are corrosion inhibitors for organic materials, in particular coating materials and lubricants. In these substrates they also act as antioxidants and light-stabilizers and are very stable to heat.
    Type: Grant
    Filed: August 17, 1987
    Date of Patent: January 16, 1990
    Assignee: Ciba-Geigy Corporation
    Inventors: Adalbert Braig, Hans-Rudolf Meier, David G. Leppard, Robert C. Wasson, Emyr Phillips
  • Patent number: 4732997
    Abstract: Photographic material containing magenta coupler is stabilized by incorporating a dibenzoxaphosphorin of the formula ##STR1## into the emulsion layer containing the coupler or into an adjoining colloid layer. The yellowing on dark storage of such material is substantially reduced as a result.The symbols A and n are defined in claim 1.
    Type: Grant
    Filed: November 18, 1986
    Date of Patent: March 22, 1988
    Assignee: Ciba-Geigy AG
    Inventors: Paul Tschopp, David G. Leppard
  • Patent number: 4661440
    Abstract: Photographic material containing magenta coupler is stabilized by incorporating a dibenzoxaphosphorin of the formula ##STR1## into the emulsion layer containing the coupler or into an adjoining colloid layer. The yellowing on dark storage of such material is substantially reduced as a result.The symbols A and n are defined in claim 1.
    Type: Grant
    Filed: November 7, 1985
    Date of Patent: April 28, 1987
    Assignee: Ciba-Geigy AG
    Inventors: Paul Tschopp, David G. Leppard
  • Patent number: 4629682
    Abstract: Recording material for color photography which contains in at least one photosensitive silver halide emulsion layer, one intermediate layer and/or one protective layer, at least one polyalkylpiperidine compound of the formula I ##STR1## in which n is the number 0 or 1 and X is a group of the formula ##STR2## or of the formula ##STR3## Color-forming agents which are obtained by imagewise exposure and development of this recording material for color photography are particularly stable towards the effect of visible and ultraviolet light.Reference is made to the description in respect of the meanings of the substituents and symbols in the formulae.
    Type: Grant
    Filed: March 28, 1985
    Date of Patent: December 16, 1986
    Assignee: Ciba-Geigy AG
    Inventors: David G. Leppard, Jean Rody
  • Patent number: 4584265
    Abstract: s-Triazine compounds which contain in their molecule at least one sterically hindered phenol group and at least one polyalkylpiperidine group are effective optical stabilizers for photographic dyes and precursors thereof.
    Type: Grant
    Filed: May 14, 1985
    Date of Patent: April 22, 1986
    Assignee: Ciba-Geigy AG
    Inventors: David G. Leppard, Jean Rody
  • Patent number: 4558131
    Abstract: Compounds which contain in their molecule both a hydroquinone monoether or resorcinol monoether radical and a polyalkylpiperidine radical are effective stabilizers for photographic dyes and their intermediates. In particular, they act as stabilizers against damage by light.
    Type: Grant
    Filed: December 15, 1983
    Date of Patent: December 10, 1985
    Assignee: Ciba-Geigy AG
    Inventors: David G. Leppard, Jean Rody