Reducer and method for conducting dot etching processing of silver image

A reducer for conducting reduction processing of blackand-white halftone images comprising (1) a ferric chelate compound of glycol ether tetraacetic acid, (2) a comlexing agent, and (3) at least one member of the compounds represented by formulae (IA) to (VIIA):

• R.sup.1A --S--M.sup.1A (IA)
• wherein M.sup.1A represents a hydrogen atom, an alkali metal atom or an ammonium group;
• and R.sup.1A represents an alkyl group, an alkylene group, an aryl group or a residue of a heterocyclic ring;
• R.sup.1A --S--S--R.sup.6A (IIA)
• wherein R.sup.1A is the same as in formula (IA);
• R.sup.6A has the same meaning as R.sup.1A ;
• and R.sup.1A and R.sup.6A are the same or different;
• ##STR23## wherein R.sup.10 and R.sup.11A are the same or different and each is a hydrogen atom, an alkyl group, an aryl group or a residue of a heterocyclic ring;
• R.sup.12A represents a hydrogen atom or an alkyl group;
• and R.sup.13A represents a hydrogen atom, an alkyl group or a carboxyl group;
• ##STR24## wherein R.sup.14A, R.sup.15A and R.sup.16A are the same or different and each is a hydrogen atom or an alkyl group;
• kB is an integer of from 1 to 5;
• and X.sup.1A represents an amino group, a sulfo group, a hydroxyl group, a carboxyl group or a hydrogen atom;
• ##STR25## wherein A.sup.1A is an nA-valent aliphatic bond group, an aromatic bond group or a heterocyclic bond group;
• ##STR26## wherein R.sup.21A is a hydrogen atom or a lower alkyl group, R.sup.17A and R.sup.18A are each an alkyl group;
• R.sup.19A is an alkyl group;
• Z.sup.2A is an anion;
• lA is 0 or 1;
• mA is 0 or 1;
• nA is 1, 2 or 3;
• pA is 0 or 1;
• and qA is 0, 1, 2, or 3;
• and R.sup.17A and R.sup.18A may be linked to each other through a carbon atom or a heteroatom to form a ring;
• ##STR27## wherein X.sup.1A and kB are the same as in formula (IVA);
• M.sup.2A represents a hydrogen atom, an alkali metal atom, an ammonium group or ##STR28## wherein R.sup.22A is a hydrogen atom or an alkyl group;
• A.sup.1 B.sup.1.sub.h A.sup.2 (Z.sup.1).sub.i (VIIA)
• wherein A.sup.1 and A.sup.2 are each ##STR29## or a residue of a saturated or unsaturated heterocyclic ring containing at least one nitrogen atom, and A.sup.1 and A.sup.2 may be the same or different;
• R.sup.1, R.sup.2 and R.sup.3 are the same or different and each is a hydrogen atom or an alkyl group;
• q is 0 or 1;
• the nitrogen atom of the heterocyclic ring may be quaternized;
• the heterocyclic ring may optionally contain an oxygen atom and/or sulfur atom;
• B.sup.1 is a bivalent organic group consisting of an alkylene group, an alkenylene group, an arylene group, ##STR30## (wherein R.sup.4 is a hydrogen atom, an alkyl group or an aryl group), alone or as a combination of two or more of them;
• h is 0 or 1;
• Z.sup.1 is an anion;
• and i is 0, 1 or 2.

A reducer for conducting reduction processing of black-and-white halftone images comprising (1) 1,3-propanediaminetetraacetic acid ferric chelate having an oxidation-reduction potential of -100 mV or above, (2) a complexing agent, and (3) at least one member of the compounds represented by formulae (IA) to (VIIA):

• R.sup.1A --S--M.sup.1A (IA)
• wherein M.sup.1A represents a hydrogen atom, an alkali metal atom or an ammonium group;
• and R.sup.1A represents an alkyl group, an alkylene group, an aryl group or a residue of a heterocyclic ring;
• R.sup.1A --S--S--R.sup.6A (IIA)
• wherein R.sup.1A is the same as in formula (IA);
• R.sup.6A has the same meaning as R.sup.1A ;
• and R.sup.1A and R.sup.6A are the same or different;
• ##STR31## wherein R.sup.10 and R.sup.11A are the same or different and each is a hydrogen atom, an alkyl group, an aryl group or a residue of a heterocyclic ring;
• R.sup.12A represents a hydrogen atom or an alkyl group;
• and R.sup.13A represents a hydrogen atom, an alkyl group or a carboxyl group;
• ##STR32## wherein R.sup.14A, R.sup.15A and R.sup.16A are the same or different and each is a hydrogen atom or an alkyl group;
• kB is an integer of from 1 to 5;
• and X.sup.1A represents an amino group, a sulfo group, a hydroxyl group, a carboxyl group or a hydrogen atom;
• ##STR33## wherein R.sup.21A is a hydrogen atom or a lower alkyl group, R.sup.17A and R.sup.18A are each an alkyl group;
• R.sup.19A is an alkyl group;
• Z.sup.2A is an anion;
• lA is 0 or 1;
• mA is 0 or 1;
• nA is 1, 2 or 3;
• pA is 0 or 1;
• and qA is 0, 1, 2, or 3;
• and R.sup.17A and R.sup.18A may be linked to each other through a carbon atom or a heteroatom to form a ring;
• ##STR34## wherein X.sup.1A and kB are the same as in formula (IVA);
• M.sup.2A represents a hydrogen atom, an alkali metal atom, an ammonium group or ##STR35## wherein R.sup.22A is a hydrogen atom or an alkyl group;
• A.sup.1 --B.sup.1.sub.h A.sup.2 (Z.sup.1).sub.i (VIIA)
• wherein A.sup.1 and A.sup.2 are each ##STR36## or a residue of a saturated or unsaturated heterocyclic ring containing at least one nitrogen atom, and A.sup.1 and A.sup.2 may be the same or different;
• R.sup.1, R.sup.2 and R.sup.3 are the same or different and each is a hydrogen atom or an alkyl group;
• q is 0 or or 1;
• the nitrogen atom of the heterocyclic ring may be quarternized;
• the heterocyclic ring may optionally contain an oxygen atom and/or sulfur atom;
• B.sup.1 is a bivalent organic group consisting of an alkylene group, an alkenylene group, an arylene group, ##STR37## (wherein R.sup.4 is a hydrogen atom, an alkyl group or an aryl group), alone or as a combination of two or more of them;
• h is 0 or 1;
• Z.sup.1 is an anion;
• and i is 0, 1 or 2.