Protective overcoats for thermally developable materials
Mixtures of an alkyl vinyl ether/maleic anhydride copolymer or an alkylethylene/maleic anhydride copolymer with cellulose acetate provide protective overcoats for thermally developable materials. These protective overcoats exhibit good adhesion to the emulsion layer, are physically hard, and have good optical clarity while maintaining the sensitometric properties of the materials.
1. A thermally developable organic-solvent based material that comprises a support having on at least one side thereon, one or more organic-solvent coated buried thermally developable imaging layers comprising a polyvinyl acetal binder, and in reactive association, a non-photosensitive source of reducible silver ions, and a reducing agent composition for said non-photosensitive source reducible silver ions, and
having disposed over the one or more organic-solvent coated buried thermally developable imaging layers, an outermost organic-solvent coated overcoat layer comprising a mixture of a cellulose acetate polymer and one or more of an alkyl vinyl ether/maleic anhydride copolymer or an alkylethylene/maleic anhydride copolymer or mixtures thereof.
2. The thermally developable material of claim 1 wherein said polyvinyl acetal binder is polyvinyl butyral.
3. The thermally developable material of claim 1 wherein said alkyl group of said alkyl vinyl ether/maleic anhydride copolymer contains from about 1 to about 4 carbon atoms.
4. The thermally developable material of claim 1 wherein said alkylethylene group of said alkylethylene/maleic anhydride copolymer contains from about 6 to about 18 carbon atoms.
5. The thermally developable material of claim 1 wherein said outermost overcoat layer further comprises a surfactant.
6. The thermally developable material of claim 5 wherein said surfactant is present in an amount of from about 0.01% to about 1.0% based on the total weight percent of all components in the overcoat formulation.
7. The thermally developable material of claim 5 wherein said surfactant is a fluorosurfactant.
8. The thermally developable material of claim 1 wherein the dry thickness of said outermost overcoat layer is from about 1 μm to about 3 μm.
9. The thermally developable material of claim 1 wherein said one or more thermally developable imaging layers is a photothermographic emulsion layer that further comprises a photosensitive silver halide.
10. The thermally developable material of claim 1 wherein said non-photosensitive source of reducible silver ions is a silver salt of an aliphatic carboxylic acid or a mixture of silver salts of aliphatic carboxylic acids, at least one of which is silver behenate.
11. The thermally developable material of claim 1 wherein the silver coating weight of said non-photosensitive source of reducible silver ions is from about 1 to less than about 2 g/m 2 .
12. The thermally developable material of claim 1 further comprising an organic-solvent coated interlayer comprising an alkyl vinyl ether/maleic anhydride copolymer or an alkylethylene/maleic anhydride copolymer or mixtures thereof that is located between said thermally developable layer(s) and the outermost overcoat layer.
13. The thermally developable material of claim 1 further comprising an organic-solvent coated interlayer comprising a mixture of a cellulose acetate polymer and one or more of an alkyl vinyl ether/maleic anhydride copolymer or an alkylethylene/maleic anhydride copolymer or mixtures thereof.
14. A thermally developable organic-solvent based material that comprises a support having on at least one side thereon, one or more organic-solvent coated buried thermally developable imaging layers comprising a polyvinyl acetal binder, and in reactive association, a non-photosensitive source of reducible silver ions, and a reducing agent composition for said non-photosensitive source reducible silver ions, and
having disposed over the one or more organic-solvent coated buried thermally developable imaging layers, an outermost organic-solvent coated overcoat layer comprising a cellulose acetate polymer, and
having an interlayer comprising an organic-solvent coated alkyl vinyl ether/maleic anhydride copolymer or an alkylethylene/maleic anhydride copolymer or mixtures thereof that is located between said thermally developable layer(s) and said outermost overcoat layer.
15. The thermally developable material of claim 14 wherein said polyvinyl acetal binder is polyvinyl butyral.
16. The thermally developable material of claim 14 wherein said alkyl group of said alkyl vinyl ether/maleic anhydride copolymer contains from about 1 to about 4 carbon atoms.
17. The thermally developable material of claim 14 wherein said alkylethylene group of said alkylethylene/maleic anhydride copolymer contains from about 6 to about 18 carbon atoms.
18. The thermally developable material of claim 14 wherein said outermost overcoat layer further comprises a surfactant.
19. The thermally developable material of claim 18 wherein said surfactant is present in an amount of from about 0.01% to about 1.0% based on the total weight percent of all components in the overcoat formulation.
20. The thermally developable material of claim 18 wherein said surfactant is a fluorosurfactant.
21. The thermally developable material of claim 14 wherein the dry thickness of the outermost overcoat layer and the interlayer is from about 1 μm to about 3 μm.
22. The thermally developable material of claim 14 wherein said one or more thermally developable imaging layers is a photothermographic emulsion layer that further comprises a photosensitive silver halide.
23. The thermally developable material of claim 14 wherein said non-photosensitive source of reducible silver ions is a silver salt of an aliphatic carboxylic acid or a mixture of silver salts of aliphatic carboxylic acids, at least one of which is silver behenate.
24. The thermally developable material of claim 14 wherein the silver coating weight of said non-photosensitive source of reducible silver ions is from about 1 to less than about 2 g/m 2 .
25. The thermally developable material of claim 14 wherein the interlayer further comprises a cellulose acetate polymer.
26. A black-and-white, organic solvent-based photothermographic material that comprises a support having on an imaging side thereon, one or more organic-solvent coated buried photothermographic emulsion layers, comprising in reactive association:
photosensitive grains of silver bromide or iodobromide that are sensitized to an exposure wavelength of at least 600 nm, one or more silver salts of aliphatic fatty acids including silver behenate, a reducing agent composition comprising a hindered phenol, a hindered bisphenol, or a combination thereof, and a polyvinyl butyral binder, and
an outermost organic-solvent coated overcoat layer disposed over said photothermographic emulsion layers, said outermost organic-solvent coated overcoat layer comprising a mixture of cellulose acetate polymer and methyl vinyl ether/maleic anhydride copolymer.
27. The black-and-white, organic solvent-based photothermographic material of claim 26 further having an organic-solvent coated interlayer comprising:
an alkyl vinyl ether/maleic anhydride copolymer or an alkylethylene/maleic anhydride copolymer or mixtures thereof that is located between said thermally developable layer(s) and said outermost overcoat layer.
28. The black-and-white, organic solvent-based photothermographic material of claim 27 wherein the interlayer further comprises a cellulose acetate polymer.
29. The black-and-white, organic solvent-based photo-thermographic material of claim 26 wherein said outermost overcoat layer further comprises a fluorosurfactant.