A photographic direct positive material is disclosed comprising a support and one or more radiation sensitive emulsion layers containing internal latent image-forming silver halide grains characterized in that at least one of said emulsion layers further contains a masked stabilizer corresponding to general formula (I) :
wherein Z represents a lower alkyl group, a nitro group or a halogen atom, n = 0 to 4, and M represents a positive counterion.
Preferred compounds are 1-(2-sulphonatobenzoyl)-5-methyl-benzotriazole, 1-(2-sulphonatobenzoyl)-6-methyl-benzotriazole or a mixture of both.
The masked stabilizer is preferably incorporated in the emulsion layer(s). The material preferably further contains a nucleating agent. Improved direct positive sensitometric properties and wider exposure latitude before encountering rereversal are obtained.
本发明公开了一种照相直接正片材料,它包括一个支撑体和一个或多个辐射敏感乳剂层,乳剂层中含有内部潜影形成的卤化
银颗粒,其特征在于所述乳剂层中至少有一层进一步含有与通式(I)相对应的掩蔽稳定剂:
其中 Z 代表低级烷基、硝基或卤素原子,n = 0 至 4,M 代表正反离子。
首选化合物为 1-(2-
磺酸基苯甲酰基)-5-甲基苯并三唑、1-(2-
磺酸基苯甲酰基)-6-甲基苯并三唑或两者的混合物。
掩蔽稳定剂最好掺入乳液层中。材料最好还含有成核剂。这样可以提高直接正感光特性,并在遇到反转之前获得更宽的曝光范围。