Fogged direct positive silver halide emulsion containing a cyanine dye having at least one benzoxazole or benzothiazole nucleus substituted with halogen atoms
AssigneeMinnesota Mining and Manufacturing Company
InventorsPaolo Beretta, Luigi Valbusa
Life of this patent
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Abstract
New cyanine dyes derived from di-halogen-benzoxazoles and benzothiazoles are desensitizers for silver halide negative emulsions and useful electron acceptor spectral sensitizers for direct positive silver halide emulsions.
Claims13
A light-sensitive fogged direct positive silver halide emulsion containing a sensitizing amount of at least one cyanine dye selected from the formulae:
- wherein
- Y is an oxygen or sulfur atom,
- n is 2, 3, or 4,
- m is 1 or 2,
- R and R.sub.1 are independently halogen atoms,
- R.sub.2 is H or an alkyl group of 1 to 4 carbon atoms,
- R.sub.3 is selected from the group consisting of acylic hydrocarbon, alkyl-aryl, or aryl groups,
- R.sub.4 is H or alkyl of 1 to 3 carbon atoms,
- Z represents the non-metallic atoms required to complete a 5 or 6 membered desensitizing heterocyclic nucleus, and
- X is an acid anion.
A light-sensitive fogged direct positive silver halide emulsion containing a sensitizing amount of 3,3'-diethyl-5,7-5',7'-tetrabromo-oxacarbocyanine perchlorate.
A light-sensitive fogged direct positive silver halide emulsion containing a sensitizing amount of 3,3'-dimethyl-5,7-5',7'-tetrabromo-9-ethyl-oxacarbocyanine perchlorate.
A light-sensitive fogged direct positive silver halide emulsion containing a sensitizing amount of 3,3'-diethyl-5,7-5',7'-tetrachloro-6,6'-dimethyloxacarbocyanine ethylsulfate.
A light-sensitive fogged direct positive silver halide emulsion containing a sensitizing amount of 3,3'-diethyl-5,6-5',6'-tetrachloro-thiacarbocyanine bromide.
A light-sensitive fogged direct positive silver halide emulsion containing a sensitizing amount of 3,3'-diethyl-5,7-5',7'-tetrachloro-thiocarbocyanine iodide.
A light-sensitive fogged direct positive silver halide emulsion containing a sensitizing amount of 3,3',9-triethyl-5,7-5',7'-tetrachloro-thiocarbocyanine iodide.
Dependencies are inferred from the claim text.