Photothermographic materials containing post-processing stabilizers
View Patent ↗1,3-Diaryl-substituted urea compounds have been found to function as post-processing stabilizers in photothermographic materials. These compounds can be presented by the following Structure (I): wherein R 1 and R 2 are the same or different substituted or unsubstituted aryl group.
1. A photothermographic material comprising a support and having on at least one side thereof a photothermographic layer comprising, in reactive association:
a. a photosensitive silver halide
b. a non-photosensitive source of reducible silver ions that is a silver carboxylate,
c. a reducing agent for said reducible silver ions,
d. a polymeric binder, and
e. at least one 1,3-diaryl-substituted urea compound represented by the following Structure (I):
wherein R 1 and R 2 are the same or different substituted or unsubstituted aryl group, and
wherein said 1,3-diaryl-substituted urea compound is present in an amount of less than 5% by weight based on the total dry weight of said binder.
2. The photothermographic material of claim 1 wherein said polymeric binder is a hydrophobic polymer or water-dispersible polymeric latex polymer.
3. The photothermographic material of claim 1 wherein said aryl-substituted urea compound is one or more of the following compounds (IU-1) through (IU-12)
4. The photothermographic material of claim 1 wherein said 1,3-diaryl-substituted urea compound represented by Structure I is present in an amount of from about 1×10 −5 to about 1×10 −2 moles/m 2 .
5. The photothermographic material of claim 1 wherein said reducing agent comprises at least a hindered bis-phenol, a hindered phenol, or mixtures thereof and said photosensitive silver halide is spectrally sensitized to infrared radiation.
6. The photothermographic material of claim 1 wherein said photosensitive silver halide is chemically sensitized with a sulfur-containing, gold-containing, tellurium-containing, and selenium-containing compound, or mixtures thereof.
7. The photothermographic material of claim 1 further comprising a polyhalogen stabilizer.
8. The photothermographic material of claim 7 wherein said polyhalogen stabilizer is represented by the formula Q-(Y) n —C(Z 1 Z 2 X) wherein, Q represents an alkyl, aryl or heterocyclic group, Y represents (C═O) or SO 2 , n is 1, and Z 1 , Z 2 , and X each represent a bromine atom, and is present in an amount of from about 0.005 to about 0.1 mol/mol of total silver.
9. The photothermographic material of claim 8 wherein said 1,3-diaryl-substituted urea compound is present in an amount of from about 0.6 to about 3% by weight based on the total dry weight of said binder.
10. The photothermographic material of claim 1 wherein at least one non-photosensitive source of reducible silver ions comprises silver behenate.
11. The photothermographic material of claim 1 further comprising a radiation absorbing substance incorporated into said photothermographic layer, such that the total absorbance of all photothermographic layers is at least 0.6 at the exposure wavelength of said photothermographic material.
12. The photothermographic material of claim 1 wherein said photosensitive silver halide is composed of preformed grains that have a number average grain size of 0.06 μm or less and the total amount of silver from all silver sources from about 0.01 to about 0.05 mol/m 2 .
13. The photothermographic material of claim 1 that provides a black-and-white image.
14. The photothermographic material of claim 1 further comprising a protective topcoat disposed over said photothermographic layer.
15. The photothermographic material of claim 14 wherein said protective topcoat is coated using a formulation containing said 1,3-diaryl-substituted urea compound.
16. The photothermographic material of claim 1 wherein said photothermographic layer is coated out of an organic solvent.
17. A black-and-white photothermographic material comprising a support and having on at least one side thereof a photothermographic layer comprising, in reactive association:
a. a photosensitive silver halide,
b. a non-photosensitive source of reducible silver ions, comprising at least silver behenate,
c. a reducing agent composition comprising one or more hindered phenol, hindered bis-phenol, or mixtures thereof,
d. a polyvinyl butyral or polyvinyl acetal binder,
e. a polyhalogen stabilizer represented by the formula Q-(Y) n —C(Z 1 Z 2 X) wherein, Q represents an alkyl, aryl or heterocyclic group, Y represents (C═O) or SO 2 , n is 1, and Z 1 , Z 2 , and X each represent a bromine atom, that is present in an amount of from about 0.01 to about 0.05 mol/mol of total silver, and
f. at least one 1,3-diaryl-substituted urea compound present in a total amount of from about 1×10 −5 to about 1×10 −2 moles/m 2 on the same side of the support as the photothermographic layer,
said 1,3-diaryl-urea compound represented by the following Structure (I):
wherein R 1 and R 2 are the same or different substituted or unsubstituted phenyl group, and
wherein said 1,3-diaryl-substituted urea compound is present in an amount of less than 5% by weight based on the total dry weight of said binder.
18. A method of forming a visible image comprising:
A) imagewise exposing the photothermographic material of claim 1 to electromagnetic radiation to form a latent image, and
B) simultaneously or sequentially, heating said exposed photothermographic material to develop said latent image into a visible image.
19. The method of claim 18 wherein said development is carried out for 15 seconds or less.
20. The photothermographic material of claim 1 further comprising phthalazine or a phthalazine derivative, or a phthalic acid derivative.