GB1375398A - - Google Patents

Abstract

1375398 Photo-conductive compositions EASTMAN KODAK CO 11 Nov 1971 [13 Nov 1970] 52393/71 Heading G2C A method of forming a heterogeneous photoconductive composition comprises dissolving one or more pyrylium, thiapyrylium or selenapyrylium dyes in an organic solvent, adding an electrically insulating polymer wherein the recurring unit includes an alkylidene diarylene residue and thoroughly mixing, cooling to a temperature below 5‹C, standing the mixture at this temperature, warming gradually to room temperature, coating a substrate with the mixture and drying. The film formed has a continuous polymer phase and a particulate phase comprising a co-crystalline complex of dye and polymer. The dye may be a salt and 94 examples are listed. The polymer may be a polycarbonate polythiocarbonate or the like and 30 examples are listed. The composition may itself constitute the photo-conductive material, or it may incorporate other photoconductors, e.g. ZnO, Cd, S, Cd, Se, organometallic, organosilicon, organophosporous and organoboron compounds having at least one aminoaryl group attached to the metal &c., atom, aryl amines, polyarylalkenes bearing at least one amine group on an aryl radical, rhodamine B, malachite green, crystal violet, phenosafranine, parachloranil, benzil, trinitrofluorenone, tetranitrofluorenone, and poly (N-vinyl) carbazoles. Specifically, 2, 6-diphenyl - 4 (p-dimethylaninophenyl) thiapyrylium fluoroborate (Example 1), 4-(4-dimethylaminophenyl)-2-(4-ethoxyphenyl)-6-phenylthiapyrylium perchlorate or 2, 6-diphenyl-4-(p-dimethylaminophenyl) thiapyrylium hexafluorophosphate (Example 3) is dissolved in a mixture of methylene chloride and 1, 1 1 2-trichloroethane, stirred for 4 hours, bisphenol A polycarbonate resin and 4, 4'- diethylamino-2, 2' - dimethyl triphenylmethane are added and the mixture stirred again, then stood for 5 days at about -5‹C (the lower the temperature the shorter the time required). The formulation is then brought to room temperature and stirred for an hour prior to coating. The optional photo-conductor compound may alternatively be added after the low temperature conditioning. The support may be conductive paper, aluminium paper laminate. Al or Zn foil, Al, Cu, Zn, brass or galvanized plates, Ag, Ni or Al vapour deposited on cellulose acetate, polyesters or polystyrene, or a coating of a semi-conductor e.g. Cu 1 dispersed in resin on polyethylene terephthalate.