Photoconductive plate for printing and a method for the preparation of a printing plate by heating

A method for preparing a printing plate in which the occurrence of fog in the non-image portions of said plate is inhibited, using a photoconductive plate which comprises a photoconductive layer including a photoconductive material and a binder on an electroconductive support,

• A. said photoconductive material comprising an organic photoconductive pigment selected from the group consisting of:
• (C.sub.8 H.sub.4 N.sub.2)Rn I.
• wherein, R is hydrogen, deuterium, sodium, potassium, copper, silver, beryllium, magnesium, calcium, zinc, cadmium, barium, mercury, aluminum, gallium, indium, lanthanum, neodymium, samarium, europium, dysprosium, holmium, erbium, thulium, ytterbium, vanadium, antimony, chromium, molybdenum, uranium, manganese, iron, cobalt, nickel, rhodium, palladium, osmium or platinum;
• and n is an integer of 0 to 2;
• ##STR29## wherein Z is --NO.sub.2, --CN, --Cl, --Br, --H, --CH.sub.3, --OC.sub.2 H.sub.5, --OH, or --N(C.sub.2 H.sub.5).sub.2 ;
• ##STR30## wherein A is ##STR31## wherein R.sup.1 and R.sup.2 independently represent a lower alkyl group, and X and Y are independently --NO.sub.2, --CN, --H, --CH.sub.3, --OCH.sub.3, --OC.sub.2 H.sub.5, --OH, --Cl, --Br, or --N(C.sub.2 H.sub.3).sub.2 ;
• ##STR32## ##STR33## ##STR34## wherein R.sup.3, R.sup.4, R.sup.5 and R.sup.6 independently represent substituents selected from the group consisting of an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, halogen, a nitro group, and an amino group, p, q, r, s, independently represent an integer of 0 to 4 and when either p, q, r or s is 2 or more, said substituents may be the same or different from each other, and the substituted groups R.sup.3, R.sup.4, R.sup.5 and R.sup.6 may be fused to form a benzene nucleus;
• ##STR35## ##STR36## in which R.sup.7 is an alkyl group, aryl group, amino group or halogen atom, and X.sup.2 and Y.sup.2 are independently --NH--, --O--, --S--, --Se--, and --Te--;
• or t represents an integer of 1 to 4;
• ##STR37## wherein Q is an alkyl group, aryl group, alkyaryl group, alkoxy group, heterocyclic substituted group or halogen atom;
• ##STR38## wherein X.sup.3 is a chlorine atom or methoxy group and k and m independently represent an integer of 0 to 5;
• ##STR39## wherein Y.sup.3 is an iodine or bromine atom, X.sup.4 represents a quinoline ring, and l represents an integer of 0, 1, 2 or 3;
• ##STR40## wherein R.sup.8 is methyl, ethyl, or allyl;
• Y.sup.4 is chlorine, bromine, or iodine;
• G and L are independently oxygen, sulfur or selenium;
• X.sup.5 is:
• ##STR41## wherein Q.sup.2 is hydrogen, methyl, or ethyl;
• and ##STR42## wherein R.sup.9, R.sup.10, R.sup.11, R.sup.12 and R.sup.13 are independently hydrogen, aliphatic or aromatic groups having one to fifteen carbon atoms, alkoxy groups, or vinyl and wherein M is sulfur, oxygen or selenium, and a pair of R.sup.9 and R.sup.10, and a pair of R.sup.12 and R.sup.13 may be a group of atoms necessary to complete a aryl ring to form a pyrylium nucleus;
• and Z.sup.2 represents anion functional groups;
• and
• B. said binder comprising an alkaline soluble phenol resin obtained by condensation of an aldehyde and at least one of phenol, O-cresol, m-cresol, and p-cresol;
• which method includes forming an image on said photoconductive layer and removing the non-image portion of the photoconductive layer by treating said layer with a removing solution, said photoconductive plate being subjected, prior to removal of said non-image portion of the photoconductive layer, to an elevated temperature sufficient so that at least 80% by volume of the photoconductive layer is removed in said non-image portion when said photoconductive layer is treated with said removing solution.