PURPOSE: To reduce fog of a photosensitive material and to improve storage stability with time by incorporating a combination of at least one selected from each of two groups of specified sensitizing dyes in a monodisperse emulsion layer contg. AgI more in the cores than in the shells in order to sensitivity to the red region.
CONSTITUTION: Red sensitivity is enhanced and especially occurrence of fog even in storage at high temps. is reduced by incorporating in an emulsion layer a combination of at least one selected from each of two groups of sensitizing dyes represented by formula I andIIin which Z1WZ8 are each H, halogen, OH, alkoxy, amino, acylamino, acyloxy, alkoxycarbonyl, alkoxycarbonylamino, aryl, alkyl, or CN, and Z5, Z8 are also aryloxycarbonyl or sulfonyl, and (Z1 and Z2) or (Z3 and Z4), (Z5 and Z6) or (Z7 and Z8) may combine and form a ring; R1, R4 are each H, alkyl, or aryl; R2, R3, R5WR8 are each alkyl; Y1WY3 are each S or Se, Y3 is also N; when Y3 is S or Se, it does not have R5; X1, X2 are each an anion; and (m), (n) are each 1 or 2, and when (m), (n) are each 1, an intramolecular salt is formed.
YAMADA YOSHITAKA
OOTANI HIROSHI
KASHIWAGI KANJI
