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US5206123A High contrast developer containing an aprotic solvent 失效
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High contrast developer containing an aprotic solvent
摘要:
A method for high contrast development of an image-wise exposed photographic element comprising a support and at least one silver halide emulsion layer, which method comprises contacting said exposed element in the presence of a hydrazine compound with an aqueous alkaline developing solution which has a pH between 10 and 13 and contains a dihydroxybenzene developing agent a 3-pyrazolidinone or an aminophenol developing agent sulphite ions and a contrast promoting amount of an amino compound characterized in that said developing solution further contains an aprotic solvent corresponding to general formula (I) or (II) : ##STR1## wherein R.sub.1 represents alkyl, substituted alkyl, alkylamino or substituted alkylamino, andR.sub.2 and R.sub.3 each independently represent alkyl substituted alkyl orwherein R.sub.1 together with R.sub.2 represent the necessary atoms to form together with the carbon and the nitrogen atom respectively to which they are attached, a heterocyclic ring, and R.sub.3 represents alkyl substituted alkyl or hydrogen;R.sub.4 and R.sub.5 each independently represent, alkyl, substituted alkyl, alkylamino or substituted alkylamino orR.sub.4 together with R.sub.5 represent the necessary atoms to form together with the sulphur atom to which they are attached a heterocyclic ring and n is 1 or 2.Preferred aprotic solvents are N,N'-dimethylacetamide, N-methyl-2-pyrrolidinone tetramethylurea, 1,3,-dimethyl-2-imidazolidinone, dimethylsulphoxide and tetramethylenesulphon.
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