GB566314A - Improvements in or relating to photographic developers - Google Patents

Abstract

566,314. Photographic developers. ELLIOTT & SONS, Ltd., HOWE, D. J. T.; and GLASSETT, J. W. June 16, 1943, No. 9630. [Class 98 (ii)] A photographic developer, other than one in which the developing agent is predominantly a paraphenylenediamine, comprises in addition to the developing agent and other constituents, a cationic surface-active agent, e.g. N-dodecyltriethylammonium bromide, N - dodecylpyridinium bromide, and N-dodecyl-alpha-picolinium bromide. The surface-active agents are not effective with developers containing a substituted or unsubstituted p-phenylenediamine. The surface-active agent may be incorporated in a stock developing powder. Developers containing hydroquinone and alkali, e.g. NaOH or KOH, and containing metol and a weak alkali, e.g. borax or trisodium phosphate, are referred to. The addition of the surface-active agent to the developer results in an effective increase in speed of the emulsion developed. The surface-active agent may be a tetra-alkyl ammonium or phosphonium salt in which one of the substituents is an organic lipophylic group containing a chain of at least 8 members selected from the group consisting of C, S and O atoms and aromatic ring systems, or may be a quarternary salt of a heterocyclic nitrogen base containing as an N- or other substituent a liphophylic group. For negative materials, up to 25 milligrams of the agent may be incorporated in 100 c.c. of metol-hydroquinone developer. For positive materials, e.g. papers, up to 2.5 c.c. of a 1 per cent solution may be added. The final image may be an ordinary or reversed silver, silver salt, other metal or metal salt, or dye image, including images obtained by toning, dye-destruction, and colour development. Examples are given of results obtained by developing test strips exposed behind step wedges.