Method of manufacturing a photothermographic material by aqueous coating and a photothermographic material prepared therewith

1. A method of manufacturing a photothermographic material comprising forming on at least one side of a support, an image forming layer comprising at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder and at least one non-photosensitive layer above the image forming layer relative to the support, wherein

50% by weight or more of the binder is formed by a polymer latex,

(1) both the image forming layer and the non-photosensitive layer are formed with aqueous coating solutions, and

(2) a coating solution for the image forming layer contains ammonium phthalate, and

(3) a pH of the coating solution for the image forming layer is from 5.0 to 7.8, and a pH of a coating solution for the non-photosensitive layer is from 4.5 to 7.0, wherein a pH difference between the coating solution for the image forming layer and a coating solution for the non-photosensitive layer is 2.0 or less.

2. The method of manufacturing a photothermographic material according to claim 1 , wherein the organic silver salt is an organic silver salt prepared by a method comprising:

a) forming crystals of an organic silver salt by a reaction between an organic acid or an alkali metal salt thereof and a water soluble silver salt,

b) removing by-product salts by filtration, and

c) dispersing the crystals of the organic silver salt into fine particles using water as a dispersion medium.

3. The method of manufacturing a photothermographic material according to claim 1 , wherein a film surface pH at a surface of the photothermographic material having the image forming layer is from 4.0 to 7.0.

4. The method of manufacturing a photothermographic material according to claim 3 , wherein the film surface pH at the surface of the photothermographic material having the image forming layer is from 5.0 to 6.0.

5. The method of manufacturing a photothermographic material according to claim 1 , wherein the pH difference is 1.5 or less.

6. The method of manufacturing a photothermographic material according to claim 1 , wherein the pH of the coating solution for the image forming layer is from 5.5 to 7.5.

7. The method of manufacturing a photothermographic material according to claim 1 , wherein the pH of the coating solution for the non-photosensitive layer is from 5.0 to 7.0.

8. The method of manufacturing a photothermographic material according to claim 1 , wherein the polymer latex comprises a monomer component having an acid group in an amount of from 1% by weight to 20% by weight.

9. The method of manufacturing a photothermographic material according to claim 1 , wherein a glass transition point (Tg) of the polymer latex is from −10° C. to 70° C.

10. The method of manufacturing a photothermographic material according to claim 1 , wherein the photothermographic material further comprises a second non-photosensitive layer provided between the image forming layer and the non-photosensitive layer, and 50% by weight or more of a binder for the second non-photosensitive layer is formed by a polymer latex.

11. The method of manufacturing a photothermographic material according to claim 1 , wherein the image forming layer and the non-photosensitive layer are coated by a simultaneous double-layer coating method.

12. The method of manufacturing a photothermographic material according to claim 5 , wherein the pH difference is 1.0 or less.

13. A photothermographic material manufactured by the manufacturing method according to claim 1 .