| 摘要 |
Optically brightened photographic material is prepared by coating a support with a dispersion prepared by mixing a photographic colloid and an aqueous emulsion of a solution, in an organic solvent, of (i) a hydrophilic resinous polymer having a refractive index similar to that of the colloid so that the polymer and colloid together yield a homogenous, transparent dispersion and (ii), an optical brightener free from acid groups. The dispersion may include the photosensitive material sion may include the photosensitive material (e.g. a gelatino silver halide emulsion optionally comprising colour couplers or bleachable dyestuffs), or it may be used to form an auxillary layer. Specified polymers are vinylidene chloride or styrene/methacrylic or acrylic alkyl ester/methacrylic or acrylic acid copolymers. and polyvinylpyrrolidone. Specified brightening agents are benzoxazoles, benzimidazoles, pyrazolones, coumarins, naphthalic acid imides, stilbenetriazole and distyrylbenzenes. The dispersions may also comprise a dispersing agent (e.g. an alkyl sulphonate) and an alkali (e.g. NH3).
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