Dye Releasing (High Dye Yield) Couplers in Photothermography

摘要

Yellow photographic dyes have low molar extinction coefficients, relative to those of magentas and cyans; therefore amplification of the yellow image by using dye-releasing couplers can be a key enabler for new imaging systems. Successful color image-forming couplers for use in camera speed photothermography are not best designed using the established principle of balancing coupling site pKa and nucleophilicity, which has been used for aqueous-processed (conventional) couplers, even though the incorporation of the couplers in photothermographic film is most conveniently done, as in conventional systems, by using photographic dispersions in high boiling solvents. In photothermography, the absence of the alkaline processing solution removes the pKa constraint and enables the design of very low pKa but efficient dye-forming couplers.