Abstract: The effect of triphenylphosphine (PPh₃) on the photographic characters of water-base PTG materials based on silver stearate as silver sources was studied.The results showed that the sensitivity of the PTG materials elevated with increasing the PPh₃ amount at a relatively low PPh₃ content;and the sensitivity reached a maximal value with increasing the PPh₃ amount till about 10%;when continuing to increase the PPh₃ amount,however,the sensitivity decreased with increasing the PPh₃ content.The analysis results supposed that the eight-membered ring of AgSt dimer was destroyed by the addition of small amount of PPh₃,and a new intermediate compound formed which accelerated the thermal development;A four-member-ring complex composed of PPh₃ and AgSt was supposed to have formed when large amount of PPh₃ was used,and the four-member-ring complex inhibited the thermal development.The introduction of PPh₃ into PTG materials could also influence the efficiency of latent image formation for light sensitive element,which contributed to improve the sensitivity.

Key words: photothermography, triphenylphosphine, photographic character, intermediate compound