Patent GB-742223-A (GB)
Title: Improvements in the preparation of photographic silver halide emulsions
IPC: G03C1/09
Filed: 1953-11-09
Abstract: 742,223. Photographic emulsions. KODAK, Ltd. Nov. 9, 1953 [Nov. 8, 1952], No. 31025/53. Class 98 (2). A photographic silver halide emulsion of which the light sensitivity has been increased by the incorporation of an onium compound also contains as a stabilizing agent a mercury salt or compound which is (a) a simple mercury salt of an organic or inorganic acid, (b) a molecular compound of a mercury salt with an organic compound containing a basic nitrogen atom, or (c) an organic mercury compound in which the mercury atom is attached by a non-ionic bond to an organic nucleus and by an ionic bond to an anion. The onium compound may be a cationic surface-active ammonium, phosphonium, or sulphonium compound as described in Specifications 556,457, 556,458 and 557,178; a polyonium cationic surface-active or non- surface-active salt containing a quaternary ammonium or phosphonium or ternary sulphonium salt linked through the onium atom by a bivalent organic radical to the onium atom of another quaternary ammonium or phosphonium or ternary sulphonium salt group as described in Specification 558,710; or a non-surface active cyclammonium quaternary salt in which the quaternary nitrogen atom is the nitrogen atom of a pyridine nucleus as described in Specification 560,082. The mercury compound may be added to the emulsion in a solvent such as water, a lower alcohol, or a ketone, at any stage before coating, e.g. after final digestion. The emulsion may be dye-sensitized, and may be chemically sensitized, in addition to the sensitization with an onium compound, by digestion with naturally active gelatine, or by addition of sulphur compounds, salts of ruthenium, rhodium, palladium, iridium, or platinum (antifoggants in higher amounts), gold salts, stannous salts, polyamines such as diethylenetriamine and spermine, or bis-(#-aminoethyl)- sulphide and its water - soluble salts. In example 1, speed, gamma and fog data are given for both fresh and incubated gelatino silver bromiodide emulsions which have been digested with a sulphur compound as disclosed in Specification 235,211 and potassium chloraurate and containing (a) no addition, (b) triethylenetetramine, (c) triethylenetetramine and ethylene bis- (oxymethylpyridiniumperchlorate), (d) addition (c) plus bis-(2-amino-5-iodopyridine hydriodide)- mercuric iodide, (e) addition (c) plus mercuric chloride, and (f) addition (c) plus pyridyl mercuric chloride. In example 2, similar data are given for an emulsion which has been digested with allyl thiourea and potassium chloraurate and with (a) no addition, (b) decamethylenebis - (oxymethylpyridinimn perchlorate, (c) addition (b) plus 2-chloromercurithiophene, and (d) addition (b) plus 8-chloromercuriquinoline. In example 3, similar data are given for an emulsion made in the same way as that of example 2 and containing (a) no addition, (b) α- picolinium-#-phenylethobromide, (c) addition (b) plus 8-chloromercuriquinoline, (d) addition (b) plus mercuric iodide, and (e) addition (b) plus mercuric nitrate. It may be added to an emulsion before or after a sensitizing dye, and the emulsion may contain a colour coupler. The emulsion binder may be gelatin, collodion, albumen, a cellulose derivative, or a synthetic resin. Specifications 235,211, [Class 98 (ii)], 602,158, 602,160, 618,061, 636,140, 658,592, 661,645, 663,019, 664,230, 680,593, 682,355, 742,219, 742,221 and 742,224 also are referred to.