Heat development image forming process thermally decoloring image recording process and process for decoloring cyanine dye

A heat development image forming process comprising steps of:

• imagewise exposing to light a heat developable light-sensitive material comprising a support, a light-sensitive layer and a non-light-sensitive layer, said light-sensitive layer containing silver halide and a reducing agent, and said non-light-sensitive layer containing a cyanine dye represented by the formula (I-1) or a salt thereof and a base precursor, wherein the cyanine dye or the salt thereof is in the form of solid particles, which are dispersed in the non-light-sensitive layer:
• in which R1 is hydrogen, an aliphatic group, an aromatic group, —NR21R24, —OR21 or —SR21, each of R21 and R24 independently is hydrogen, an aliphatic group or an aromatic group, or R21 and R24 are combined to form a nitrogen-containing heterocyclic ring;
• R2 is hydrogen, an aliphatic group or an aromatic group;
• R3 is an aliphatic group;
• L1 is a trimethine or a pentamethine;
• and each of Z1 and Z2 independently is an atomic group forming a five-membered or six-membered nitrogen-containing heterocyclic ring, which may be condensed with an aromatic ring;
• and then heating the heat developable light-sensitive material at 80 to 200° C. to form a base from the base precursor whereby the cyanine dye is decolored and to develop the silver halide.

A thermal image recording material comprising a support and an image recording layer, said image recording layer containing a cyanine dye represented by the formula (I-1) or a salt thereof and a base precursor, wherein the cyanine dye or the salt thereof is in the form of solid particles, which are dispersed in the image recording layer:

• in which R1 is hydrogen, an aliphatic group, an aromatic group, —NR21R24, —OR21 or —SR21, each of R21 and R24 independently is hydrogen, an aliphatic group or an aromatic group, or R21 and R24 are combined to form a nitrogen-containing heterocyclic ring;
• R2 is hydrogen, an aliphatic group or an aromatic group;
• R3 is an aliphatic group;
• L1 is a trimethine chain or a pentamethine chain;
• and each of Z1 and Z2 independently is an atomic group forming a five-membered or six-membered nitrogen-containing heterocyclic ring, which may be condensed with an aromatic ring.

A thermally decoloring image recording process comprising imagewise heating a thermal image recording material at 80 to 200° C., said image recording material comprising a support and an image recording layer, said image recording layer containing a cyanine dye represented by the formula (I-1) or a salt thereof and a base precursor, wherein the cyanine dye or the salt thereof is in the form of solid particles, which are dispersed in the image recording layer:

• in which R1 is hydrogen, an aliphatic group, an aromatic group, —NR21R24, —OR21 or —SR21, each of R21 and R24 independently is hydrogen, an aliphatic group or an aromatic group, or R21, and R24 are combined to form a nitrogen-containing heterocyclic ring;
• R2 is hydrogen, an aliphatic group or an aromatic group;
• R3 is an aliphatic group;
• L1 a trimethine chain or a pentamethine chain;
• and each of Z1 and Z2 independently is an atomic group forming a five-membered or six-membered nitrogen-containing heterocyclic ring, which may be condensed with an aromatic ring;
• to form a base from the base precursor whereby the cyanine dye is decolored.

A process for decoloring a cyanine dye comprising heating a cyanine dye represented by the formula (II-1) or a salt thereof at 80 to 200° C. in the presence of a base:

• in which X21 is —NR24—, —O— or —S—;
• each of R21 and R24 independently is hydrogen, an aliphatic group or an aromatic group, or R21 and R24 are combined to form a nitrogen-containing heterocyclic ring;
• R22 is hydrogen, an aliphatic group or an aromatic group;
• R23 is an aliphatic group;
• L21 is a trimethine chain or a pentamethine chain;
• and each of Z21 and Z22 independently is an atomic group forming a five-membered or six-membered nitrogen-containing heterocyclic ring, which may be condensed with an aromatic ring.