Silver compounds and compositions, thermally developable materials containing same, and methods of preparation
Novel silver compounds can include a primary core of a photosensitive silver halide and a shell covering the primary core. This shell includes one or more non-photosensitive silver salts, each silver salt including an organic silver coordinating ligand. Other novel silver compounds are homogeneous silver salts of organic silver coordinating ligands throughout (non-core-shell). Still other silver compounds can include a primary core of a non-photosensitive metal salt and a shell covering the primary core. This shell includes one or more non-photosensitive silver salts, each silver salt including an organic silver coordinating ligand. These types of silver compounds can be used as sources of reducible silver ions in thermally developable imaging materials including thermographic and photothermographic materials.
1. A thermally developable emulsion comprising:
a) a source of non-photosensitive silver ions comprising a core-shell silver compound comprising a primary core comprising one or more photosensitive silver halides, and a shell completely covering said primary core, wherein said shell comprises one or more non-photosensitive silver salts, each of which silver salts comprises an organic silver coordinating ligand that contains an imino group or a long chain aliphatic carboxylate,
b) a reducing composition for said non-photosensitive silver ions, and
c) a binder.
2. A thermally developable imaging material comprising a support having thereon one or more imaging layers comprising:
a) a source of non-photosensitive silver ions comprising a core-shell silver compound comprising a primary core comprising one or more photosensitive silver halides, and a shell completely covering said primary core, wherein said shell comprises one or more non-photosensitive silver salts, each of which silver salts comprises an organic silver coordinating ligand that contains an imino group or a long chain aliphatic carboxylate,
b) a reducing composition for said non-photosensitive silver ions, and
c) a binder.
3. The thermally developable material of claim 2 that provides a color image and wherein said reducing composition comprises a dye-forming or -releasing compound.
4. The thermally developable imaging material of claim 2 wherein the molar ratio of said one or more non-photosensitive silver salts in said shell to said one or more silver halides in said primary core is from about 100:1 to about 1:100.
5. The thermally developable imaging material of claim 2 wherein said primary core contains predominantly silver bromide.
6. The thermally developable imaging material of claim 2 wherein said primary core contains silver chlorobromide, silver iodobromide, or silver bromide.
7. The thermally developable imaging material of claim 2 wherein said shell comprises a mixture of silver salts comprising different organic silver coordinating ligands.
8. The thermally developable imaging material of claim 7 wherein said shell comprises a silver long chain aliphatic carboxylate as one of said silver salts.
9. The thermally developable imaging material of claim 2 wherein said core-shell silver compound has an average particle size of from about 50 nm to about 10 μm.
10. The thermally developable imaging material of claim 2 wherein said core-shell silver compound has a primary core composed of an inner region comprising a first silver halide and an outer region comprising a different silver halide.
11. The thermally developable imaging material of claim 10 wherein said core-shell silver compound has an inner region composed predominantly of a mixture of silver bromide and silver iodide and an outer region composed of predominantly silver bromide.
12. The thermally developable imaging material of claim 2 wherein said organic silver coordinating ligand contains imino groups.
13. The thermally developable imaging material of claim 12 wherein said organic silver coordinating ligand is a benzotriazole or substituted derivative thereof, a 1,2,4-triazole, a 1-H-tetrazole, or an imidazole or imidazole derivative.
14. A thermally developable emulsion comprising:
a) a source of non-photosensitive silver ions comprising a core-shell silver compound comprising a primary core comprising calcium fluoride, and a shell covering said primary core, wherein said shell comprises one or more non-photosensitive silver salts, each of which non-photosensitive silver salts comprises an organic silver coordinating ligand,
b) a reducing composition for said non-photosensitive silver ions, and
c) a binder.
15. The thermally developable emulsion of claim 14 wherein said one or more one or more organic silver coordinating ligands comprises a long chain aliphatic carboxylate, a benzotriazole or a substituted derivative thereof, or a mixture of two or more of these.
16. A thermally developable imaging material comprising a support having thereon one or more imaging layers comprising:
a) a source of non-photosensitive silver ions comprising a core-shell silver compound comprising a primary core comprising calcium fluoride, and a shell covering the primary core, wherein the shell comprises one or more non-photosensitive silver salts, each of which non-photosensitive silver salts comprises an organic silver coordinating ligand,
b) a reducing composition for said non-photosensitive silver ions, and
c) a binder.
17. The thermally developable imaging material of claim 16 wherein said one or more one or organic silver coordinating ligands comprises a long chain aliphatic carboxylate, a benzotriazole or a substituted derivative thereof, or a mixture of two or more of these.