GB789842A - Improvements in photographic silver halide emulsions - Google Patents

Abstract

789,842. Photographic emulsions. KODAK, Ltd. Jan. 3, 1956 [Jan. 3, 1955], No. 134/56. Class 98(2) A light-sensitive silver halide emulsion contains an antifoggant of the general formula wherein R is an alkylmercapto, a substituted alkylmercapto, or monoalkylamino group and R1 is H or lower alkyl. Compounds specified are (a) 2 - carboxymethylmercapto - 5 - methyl - 4 oxo - 6 - thiono - 4 : 5 : 6 : 7- tetrahydro - 1 thia - 3 : 5 : 7 - triazaindene, (b) 5 - methyl - 2 - methylmercapto - 4 - oxo - 6 - thiono - 4 : 5 - 6 : 7 tetrahydro - 1 - thia - 3 : 5 : 7 - triazaidene, and (c) 2 methylamino - 4 - oxo - 6 - thiono - 4 : 5 : 6 : 7 - tetrahydro- 1 - thia 3 : 5 : 7 - triazaindene. The compound may also be incorporated in a colloid layer e.g. a gelatin overcoating or interlayer, in contact with the emulsion. The compound may be incorporated in an emulsion which has not been specially sensitized. or in an emulsion which has been optically sensitized or chemically sensitized, e.g. by addition of an alkylene oxide polymer or derivative thereof (e.g. polymers of ethylene, propylene or butylene oxides or condensation products of alkylene oxides with glycols, phenols, aliphatic alcohols, aliphatic acids, aliphatic amines, or hexitol ring dehydration products), by digestion with naturally active gelatin, or by addition of sulphur compounds, salts of ruthenium. rhodium, palladium, iridium or platinum (these act as antifoggants in higher amounts), gold salts. stannous salts, or polyamines such as diethylenetriamine, spermine, or bis - (# - aminoethyl) - sulphide and its water-soluble salts. The emulsion may also be stabilized by the addition of a mercury compound as described in Specifications 742,219, 742,221, and 742,224. A table is given showing speed, gamma and fog values before and after incubation for a panchromatically sensitized silver bromoidide emulsion chemically sensitized with a sulphur compound and potassium chloraurate without further addition and with the addition of compounds (a), (b), and (c), each in two different amounts. Specifications 235,211 [Class 98(2)], 380,431, 380,851 [both in Group IV], 548,019, 592,676, 600,058, 602,158, 602,160, 618,061, 636,140, 658,592, 661,645, 663,019, 664,230, 680,593, 682,355, also are referred to.