| 摘要 |
734,474. Photographic emulsions. KODAK, Ltd. Nov. 6, 1953 [Nov. 8, 1952], No. 30700/53. Class 98 (2). A light-sensitive silver halide emulsion contains a sulphur sensitizer, a gold salt sensitizer, and either spermine, a polyamine of the general formula H 2 N.(RNH) n .RNH 2 (wherein R is an alkylene chain of to 4 carbon atoms and n is 1 to 5), or a water-soluble salt of spermine or the polyamine with a non-desensitizing acid. The sulphur sensitizer may be thiourea, di-otolyl thiourea, allyl isothiocyanate, thiocarbanilide, sodium thiosulphate, thioacetamide; or allyl thiourea, the gold salt sensitizer may be potassium chloraurate, gold chloride, or potassium aurothiocyanate, and the water-soluble salt of the spermine or polyamine may be the acetate, carbonate, sulphate, or hydrochloride. The sensitizers may be incorporated into the emulsion at any stage, but preferably before completion of'digestion, it being preferred to partially digest the emulsion after the addition of the sulphur and gold salt sensitizers and to finish digestion after addition of the polyamine sensitizer. Speed, gamma, and fog data are given for emulsions containing (a) allyl thiourea and potassium chloraurate; (b) as (a) plus triethylenetetramine; (c) as (a); (d) and (e) as (c) containing different quantities of triethylenetetramine; (f) as (a); (g) and (h) as (f) containing different quantities of spermine tetrachloride; (i) as (a); (j), (k) and (1) as (i) containing different quantities of triethylene tetramine; (m) as (a); (n) as (m) containing triethylenetetramine; (o) as (n) containing benztriazole; (p) as (a); and (q), (r), (s) and (t) as (p) containing different quantities of triethylenetetramine. Final digestion of the emulsion with the polyamine compound at pH 6.0 suppresses fog which might arise through extended digestion. The emulsions, which may be coated in single- or multi-layer coatings, may contain anti-fogging and spreading agents and colour couplers. Specifications 570,393, 631,243, 636,140, 661,645 and 663,019 are referred to. |
