Subbing layers for use with thermographic materials

A process for producing a substantially light-insensitive thermographic material comprising (a) a polymeric or polymer-coated support;

• (b) a subbing layer on said support, (i) which contains a subbing layer binder selected from the group consisting of polymer latex, polysilicic acid, melamine-formaldehyde resin, hydrolyzed polyalkoxysilanes and any mixture thereof, and when said binder contains covalently bonded acid groups, said acid groups are substantially present as free acids or substantially present as acid salts, (ii) wherein said subbing layer has a leachable non-fluoro halide ion content into water at room temperature over a period of 120 minutes of less than 0.6 mg/m2 and, (iii) wherein said subbing layer contains silica and less than 20% by weight of said subbing layer is silica, and (c) a thermosensitive element on the same side of said support as said subbing layer, said thermosensitive element containing (i) a substantially light-insensitive organic silver salt, (ii) a reducing agent for the reduction of the substantially light-insensitive organic silver salt and (iii) a thermosensitive element binder, said process comprising the steps of:
• (A) coating said support with a subbing layer composition to form said subbing layer;
• (B) producing one or more aqueous coating compositions together containing said substantially light-insensitive organic silver salt, said reducing agent and said thermosensitive element binder;
• and
• (C) applying said one or more of said aqueous coating compositions to the same side support as said subbing layer to form after drying, said thermosensitive element.

A substantially light-insensitive black and white thermographic material comprising

• (a) a polymeric or polymer-coated support,
• (b) a subbing layer on said support
• (i) which contains a subbing layer binder selected from the group consisting of polyethylene wax, polymer latex and mixtures thereof, and when said binder contains covalently bonded acid groups, said acid groups are substantially present as free acids or substantially present as acid salts,
• (ii) wherein said subbing layer has a leachable non-fluoro-halide ion content into water at room temperature over a period of 120 minutes of less than 0.6 mg/m2, and
• (iii) wherein less than 20% by weight of said subbing layer is silica,
• (c) a thermosensitive element on the same side of said support as said subbing layer, said thermosensitive element containing
• (i) a substantially light-insensitive organic silver salt,
• (ii) a reducing agent for the reduction of the substantially light insensitive organic silver salt and
• (iii) a thermosensitive element binder.

A process for producing a substantially light-insensitive thermographic material comprising (a) a polymeric or polymer-coated support, (b) a subbing layer on said support, (i) which contains polyethylene wax as a subbing layer binder, (ii) wherein said subbing layer has a leachable non-fluoro halide ion content into water at room temperature over a period of 120 minutes of less than 0.6 mg/m2, and (iii) wherein less than 20% by weight of said subbing layer is silica and (c) a thermosensitive element on the same side of said support as said subbing layer, said thermosensitive element containing (i) a substantially light-insensitive organic silver salt, (ii) a reducing agent for the reduction of the substantially light-insensitive organic silver salt and (iii) a thermosensitive element binder, said process comprising the steps of:

• (A) coating said support with a subbing layer composition to form said subbing layer;
• (B) producing one or more aqueous coating compositions together containing said substantially light-insensitive organic silver salt, said reducing agent and said thermosensitive element binder;
• and
• (C) applying said one or more of said aqueous coating compositions to the same side of the support as said subbing layer to form after drying, said thermosensitive element.