Oji Paper Co., Ltd.

Koji Sato

Masahiro Yamana

An electrophotographic lithograph printing plate material having an enhanced sensitivity to laser rays, an excellent heat resistance and a low dark decay comprises an electroconductive, water-resistant substrate and an electrophotographic layer comprising a photoconductive zinc oxide, a resinous binder and a sensitizing dye material which comprises at least one compound (A) of the formula (I) and at least one compound (B) of the formula (II): ##STR1## wherein each of A.sub.1 and A.sub.2 represents a C.sub.5-7 polymethine group non-substituted or substituted with at least one substituent, for example, --Cl, the substituted polymethine group may have a cyclic structure, for example, of: ##STR2## each of from B.sub.1 to B.sub.4 is a divalent non-substituted or substituted, benzene or naphthalene group, each of from X.sub.1 to X.sub.4 is a S, Se, or O atom or a --C(CH.sub.3).sub.2 -- group, each of from R.sub.1 to R.sub.4 is a C.sub.1-5 alkyl group, each of M.sub.1 and M.sub.5 is a metal atom, organic base or hydrogen atom, each of Y.sub.1 and Y.sub.2 is an anion, and m and n is zero or 1 but when n= 1, m= 1 and when n= 0, m= 0 and --R.sub.3 COO group adjacent to the (M.sub.1).sub.m group in the formula (II) is anionic, the weight ratio of the compound (A) to the compound (B) being 3:1 to 20:1.

Electrophotographic lithograph printing plate material having a mixture

An electroghraphic lithograph printing plate material having an enhanced spectral sensitivity to semiconductor laser rays, comprises a electroconductive water-resistant support and electrophotographic layer formed on the support and comprising a photoconductive zinc oxide, a binder resin and a sensitizing dye material comprising (a) 30 to 99% by weight of a low adsorption sensitizing dye for which the zinc oxide exhibits a low adsorption rate of less than 90% and (b) 1 to 70% by weight of a high adsorption sensitizing dye for which the zinc oxide exhibits a high adsorption rate for 90% or more, the adsorption rate being measured by spectrophotometry.

Electrophotographic lithograph printing plate material

An electrophotographic material having an enhanced sensitivity to laser rays comprises,

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Kodaira, Japan

Koji Sato