Stabilizers for photothermography with nitrile blocking groups

Photothermographic compositions comprising a photographic silver halide, an organic silver salt, and a reducing agent for the organic silver salt, display improved stabilty in the presence of a compound having a nucleus of the formula: ##STR1## wherein: A represents any monovalent group for which the corresponding compound AH functions as a post-processing stabilizer, PA0 R.sup.1, R.sup.2, and R.sup.3, are independently hydrogen or methyl and with the proviso that R.sup.1 can represent an aryl group when R.sup.2 and R.sup.3 are hydrogen; PA0 R.sup.4 is hydrogen or lower alkyl of from 1 to 4 carbon atoms; PA0 R.sup.5 and R.sup.6 independently represent hydrogen, an alkyl group, a cycloalkyl group, an aryl group or R.sup.5 and R.sup.6 taken together with the carbon atom to which they are joined form a ring of 4 to 12 atoms; PA0 R.sup.7 and R.sup.8 are independently hydrogen or lower alkyl of 1 to 4 carbon atoms; and PA0 n is 0 or 1.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to photothermographic materials and in particular to 
post-processing stabilization of photothermographic silver-containing 
materials. 
2. Background of the Art 
Silver halide containing photothermographic imaging materials processed 
with heat, and without liquid development have been known in the art for 
many years. These materials, also known as dry silver materials, generally 
comprise a support having thereon a photographic light-sensitive silver 
halide, a light-insensitive organic silver salt, and a reducing agent for 
the organic silver salt. 
The light-sensitive silver halide is in catalytic proximity to the 
light-insensitive organic silver salt so that the latent image, formed by 
irradiation of the silver halide, serves as a catalyst nucleus for the 
oxidation-reduction reaction of the organic silver salt with the reducing 
agent when the emulsion is heated above about 80.degree. C. Such media are 
described, for example, in U.S. Pat. Nos. 3,457,075, 3,839,049, and 
4,260,677. The silver halide may also be generated in the media by a 
preheating step in which halide ion is released to form silver halide. 
A variety of ingredients may be added to these basic components to enhance 
performance. For example, toning agents may be incorporated to improve the 
color of the silver image of the photothermographic emulsions, as 
described in U.S. Pat. Nos. 3,846,136; 3,994,732 and 4,021,249. Various 
methods to produce dye images and multicolor images with photographic 
color couplers and leuco dyes are known and described in U.S. Pat. Nos. 
4,022,617; 3,531,286; 3,180,731; 3,761,270, 4,460,681; 4,883,747 and 
Research Disclosure, March 1989, item 29963. 
A common problem that exists with photothermographic systems is 
post-processing instability of the image. The photoactive silver halide 
still present in the developed image may continue to catalyze print-out of 
metallic silver during room light handling or exposure to heat or 
humidity. Thus, there exists a need for stabilization of the unreacted 
silver halide. The addition of separate post-processing image stabilizers 
has been used to impart post-processing stability. Most often these are 
sulfur-containing compounds such as mercaptans, thiones, and thioethers as 
described in Research Disclosure, June 1978, item 17029. U.S. Pat. Nos. 
4,245,033; 4,837,141 and 4,451,561 describe sulfur compounds that are 
development restrainers for photothermographic systems. Mesoionic 
1,2,4-triazolium-3-thiolates as fixing agents and silver halide 
stabilizers are described in U.S. Pat. No. 4,378,424. Substituted 
5-mercapto-1,2,4-triazoles such as 3-amino-5-benzothio-1,2,4-triazole as 
post-processing stabilizers are described in U.S. Pat. Nos. 4,128,557; 
4,137,079; 4,138,265, and Research Disclosure, May 1978, items 16977 and 
16979. U.S. Pat. Nos. 5,158,866 and 5,194,623 describe the use of 
omega-substituted 2-propionamidoacetyl or 3-propionamidopropionyl 
stabilizer precursors as post-processing stabilizers in photothermographic 
emulsions. U.S. Pat. No. 5,175,081 discribes the use of certain azlactones 
as stabilizers. 
Problems arising from the addition of stabilizers may include thermal 
fogging during processing and losses in photographic speed, maximum 
density or contrast at effective stabilizer concentrations. 
Stabilizer precursors are materials which have blocking or modifying groups 
that are usually cleaved during processing with heat and/or alkali. The 
cleaving provides the primary active stabilizer which can combine with the 
photoactive silver halide in the unexposed and undeveloped areas of the 
photographic material. For example, in the presence of a stabilizer 
precursor in which a sulfur atom is unblocked upon processing, the 
resulting silver mercaptide will be more stable than the silver halide to 
light, atmospheric, and ambient conditions. 
Various blocking techniques have been utilized in developing the stabilizer 
precursors. U.S. Pat. No. 3,615,617 describes acyl blocked 
photographically useful stabilizers. U.S. Pat. Nos. 3,674,478 and 
3,993,661 describe hydroxyarylmethyl blocking groups. Benzylthio releasing 
groups are described in U.S. Pat. No. 3,698,898. Thiocarbonate blocking 
groups are described in U.S. Pat. No. 3,791,830, and thioether blocking 
groups in U.S. Pat. Nos. 4,335,200, 4,416,977, and 4,420,554. 
Photographically useful stabilizers which are blocked as urea or thiourea 
derivatives are described in U.S. Pat. No. 4,310,612. Blocked imidomethyl 
derivatives are described in U.S. Pat. No. 4,350,752, and imide or 
thioimide derivatives are described in U.S. Pat. No. 4,888,268. Removal of 
all of these aforementioned blocking groups from the photographically 
useful stabilizers is accomplished by an increase of pH during alkaline 
processing conditions of the exposed imaging material. 
Thermally sensitive blocking groups are also known. These blocking groups 
are removed by heating the imaging material during processing. 
Photographically useful stabilizers blocked as thermally sensitive 
carbamate derivatives are described in U.S. Pat. Nos. 3,844,797 and 
4,144,072. These carbamate derivatives presumably regenerate the 
photographic stabilizer through loss of an isocyanate. Hydroxymethyl 
blocked photographic reagents which are deblocked through loss of 
formaldehyde during heating are described in U.S. Pat. No. 4,510,236. 
Development inhibitor releasing couplers releasing tetrazolylthio moieties 
are described in U.S. Pat. No. 3,700,457. Substituted benzylthio releasing 
groups are described in U.S. Pat. No. 4,678,735. U.S. Pat. Nos. 4,351,896 
and 4,404,390 utilize carboxybenzylthio blocking groups for mesoionic 
1,2,4-triazolium-3-thiolate stabilizers. Photographic stabilizers that are 
blocked by a Michael-type addition to the carbon-carbon double bond of 
either acrylonitrile or alkyl acrylates are described in U.S. Pat. Nos. 
4,009,029 and 4,511,644, respectively. Heating of these blocked 
derivatives causes unblocking by a retro-Michael reaction. 
Various disadvantages attend these different blocking techniques. Highly 
basic solutions necessary to cause deblocking of the alkali sensitive 
blocked derivatives are corrosive and irritating to the skin. With 
photographic stabilizers that are blocked with a heat removable group, it 
is often found that the liberated reagent or by-product can react with 
other components of the imaging construction and cause adverse effects. 
Also, inadequate or premature release of the stabilizing moiety during 
heat processing may occur. 
There has been a continued need for improved post-processing stabilizers or 
stabilizer precursors that do not fog or desensitize photothermographic 
materials, and for stabilizer precursors that release the stabilizing 
moiety at the appropriate time and do not have any detrimental effects on 
the photosensitive material or its user. 
Blocking groups which are removed by actinic radiation are discussed in the 
context of organic synthesis utility in Amit et al., Israel J. Chem.1974, 
12, 103; and V. N. R. Pillai, Synthesis, 1980, 1-26. The o-nitrobenzyl 
group has been known as a photocleavable blocking group for some time (J. 
Barltrop et al, J. Chem. Soc. Chem. Comm.1966, 822-823.) Various 
substituted analogues have been prepared in order to maximize the 
photochemical efficiency and chemical yield, and to suppress colored 
products of the photolysis. The o-nitrobenzyl group has been used to 
protect many different functional groups, including carboxylic acids, 
amines, phenols, phosphates, and thiols. 
Photolytically active stabilizer precursors for photothermographic silver 
imaging compositions which apparently release bromine atoms are described 
in U.S. Pat. No. 4,459,350. 
U.S. Pat. No. 4,207,108 describes the use of thione compounds as a 
photographic speed enhancing additive, U.S. Pat. No. 4,873,184 describes 
the use of metal chelating agents to enhance speed in silver halide 
systems, and U.S. Pat. No. 4,264,725 describes the use of benzyl alcohol 
and 2-phenoxyethanol as speed enhancing solvents for photothermographic 
materials. 
Stabilizer precursors of the present invention can be added to 
photothermographic formulations without the necessity of rebalancing the 
formulation to compensate for effects on sensitometry, as is often the 
case with other stabilizers in the art. 
SUMMARY OF THE INVENTION 
In one aspect this invention relates to photothermographic articles 
comprising a photothermographic composition coated on a substrate wherein 
the photothermographic composition comprises a photosensitive silver salt, 
an organic silver salt, and a reducing agent for the organic silver salt, 
and a post-processing stabilizer having a central nucleus of the formula: 
##STR2## 
wherein: A represents a post-processing stabilizer group in which a 
hydrogen atom of the post-processing stabilizer (AH) has been replaced by 
##STR3## 
R.sup.1, R.sup.2, and R.sup.3, are independently hydrogen or methyl and 
with the proviso that R.sup.1 can represent an aryl group when R.sup.2 and 
R.sup.3 are hydrogen; 
R.sup.4 can be hydrogen or lower alkyl (of from 1 to 4 carbon atoms); 
R.sup.5 and R.sup.6 independently represent hydrogen, an alkyl group, a 
cycloalkyl group, an aryl group or R.sup.5 and R.sup.6 taken together with 
the carbon atom to which they are joined form a ring of 4 to 12 atoms; 
R.sup.7 and R.sup.8 are independently hydrogen or lower alkyl of 1 to 4 
carbon atoms; and 
n is 0 or 1; 
Preferably the compound has the formula: 
##STR4## 
wherein: 
A represents any monovalent group for which the corresponding compound AH 
functions as a post-processing stabilizer having from 1 to 50 carbon 
atoms. The A groups may of course independently bear substituents that are 
photographically inert or physically useful (e.g., solubilizing, 
ballasting, etc.) and the substituent may be independently represented by 
a group R selected from hydrogen, alkyl, alkoxycarbonyl, alkenyl, aryl, 
hydroxy, mercapto, amino, amido, thioamido, carbamoyl, thiocarbamoyl, 
cyano, nitro, sulfo, carboxyl, fluoro, formyl, sulfoxyl, sulfonyl, 
hydrodithio, ammonio, phosphonio, silyl, and silyloxy groups having up to 
18 carbon atoms, and wherein any two or three R groups such as R.sup.9, 
R.sup.10, and R.sup.11 may together form a fused ring structure with any 
central benzene ring. 
The compounds of the present invention typically comprise from about 0.01 
wt % to 10 wt % of the dry photothermographic composition. They may be 
incorporated directly into the silver containing layer or into an adjacent 
layer. The stabilizers of the invention are especially useful in articles 
and compositions for the preparation of photothermographic color and 
photothermographic black-and-white images. 
The stabilizers of the present invention stabilize silver halide and/or 
minimize untimely leuco oxidation for improved post-processing 
stabilization without desensitization or fogging during heat processing. 
The stabilizers of this invention are believed to be deblocked to release 
the parent stabilizer by the action of heat and therefore offer advantages 
over unprotected stabilizers and stabilizers released by other mechanisms 
by being inert and inactive during the processing step, and being 
resistant to thermal release during shelf aging. They are only released 
when they are needed. They are useful in a wide range of 
photothermographic media and processing conditions, since they do not 
appear to have specific requirements for release that attend most other 
masking groups. 
Whether or not specifically describing substituents, substitution is 
anticipated on the compounds of the present invention. Where the term 
"group" or "nucleus" is used, these terms include the use of additional 
substituents beyond the literal definition of alkyl or the nucleus. For 
example, alkyl group includes ether groups (e.g., CH.sub.3 --CH.sub.2 
--CH.sub.2 --O--CH.sub.2 --), haloalkyls, nitroalkyls, carboxyalkyls, 
hydroxyalkyls, sulfoalkyls, etc. while the term "alkyl moiety" or "alkyl 
radical" or "alkyl moiety" includes only hydrocarbons. Substituents which 
react with active ingredients, such as very strongly electrophilic or 
oxidizing substituents, would of course be excluded by the ordinarly 
skilled artisan as not being inert or harmless.

DETAILED DESCRIPTION OF THE INVENTION 
Photothermographic articles of the present invention comprise a 
photothermographic composition coated on a substrate wherein the 
photothermographic construction comprises a photographic silver salt, an 
organic silver salt, a reducing agent for the organic silver salt, and a 
stabilizer having the formula: 
##STR5## 
wherein: A represents a post-processing stabilizer in which a hydrogen 
atom of the post-processing stabilizer (AH) has been replaced by 
##STR6## 
R.sup.1, R.sup.2, and R.sup.3, are independently hydrogen or methyl and 
with the proviso that R.sup.1 can represent an aryl group when R.sup.2 and 
R.sup.3 are hydrogen; 
R.sup.4 can be hydrogen or lower alkyl of from 1 to 4 carbon atoms; 
R.sup.5 and R.sup.6 independently represent hydrogen, an alkyl group, a 
cycloalkyl group, an aryl group or R.sup.5 and R.sup.6 taken together with 
the carbon atom to which they are joined form a ring of 4 to 12 atoms; 
R.sup.7 and R.sup.8 are independently hydrogen or lower alkyl of 1 to 4 
carbon atoms; and 
n is 0 or 1; 
Preferably the compound has the formula: 
##STR7## 
wherein: A represents any monovalent group for which the corresponding 
compound AH functions as a post-processing stabilizer having from 1 to 50 
carbon atoms. The A groups may of course independently bear substituents 
that are photographically inert or physically useful (e.g., solubilizing, 
ballasting, etc.) and the substituent may be independently represented by 
a group R selected from hydrogen, alkyl, alkoxycarbonyl, alkenyl, aryl, 
hydroxy, mercapto, amino, amido, thioamido, carbamoyl, thiocarbomoyl, 
cyano, nitro, sulfo, carboxyl, fluoro, formyl, sulfoxyl, sulfonyl, 
hydrodithio, ammonio, phosphonio, silyl, and silyloxy groups having up to 
18 carbon atoms in any one of these groups, and wherein any two or three R 
groups such as R.sup.9, R.sup.10, and R.sup.11 may together form a fused 
ring structure with any central benzene ring. 
In photothermographic articles of the present invention the layer(s) that 
contain the photographic silver salt are referred to herein as emulsion 
layer(s). According to the present invention the blocked stabilizer is 
added either to one or more emulsion layers or to a layer or layers 
adjacent to one or more emulsion layers. Layers that are adjacent to 
emulsion layers may be, for example, primer layers, image-receiving 
layers, interlayers, opacifying layers, antihalation layers, barrier 
layers, auxiliary layers, etc. 
The bridging group acts as a blocking group to block the activity of the 
primary stabilizer AH. If AH is left unblocked and added to the 
photothermographic emulsion at the same molar equivalent concentration as 
the blocked compound, AH desensitizes or fogs the emulsion. Deblocking to 
release the active stabilizer occurs after exposure and development at 
elevated temperatures. Thus, the blocked stabilizers of the present 
invention overcome the problems of desensitization and fogging that occur 
when the stabilizers are use in their unblocked form. 
A is preferably attached through a nitrogen atom. Post-processing 
stabilizing groups for stabilizing silver ion AH usually have a heteroatom 
such as nitrogen available for complexing silver ion. The compounds are 
usually ring structures with the heteroatom within the ring or external to 
the ring. These compounds are well known to one ordinarily skilled in the 
photographic art. Non-limiting examples of AH include nitrogen-containing 
heterocycles, substituted or unsubstituted, including but not limited to, 
imidazoles such as benzimidazole and benzimidazole derivatives; triazoles 
such as benzotriazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, and 
2-thioalkyl-5-phenyl-1,2,4-triazoles; tetrazoles such as 5-amino tetrazole 
and phenylmercaptotetrazole; triazines such as mercaptotetrahydrotriazine; 
piperidones; tetraazaindans; 8-azaguanine; thymine; thiazolines such as 
2-amino-2-thiazoline, indazoles; hypoxanthines; pyrazolidinones 
2H-pyridooxazin-3(4H)-one and other nitrogen-containing heterocycles; or 
any such compound that stabilizes the emulsion layer, and particularly 
those that have deleterious effects on the initial sensitometry or 
excessive fog is used unblocked. 
Many of such compounds are summarized in Research Disclosure, March 1989, 
item 29963. AH may also be a compound which stabilizes a leuco dye, 
usually a reducing agent which has an active hydrogen which can be masked 
by replacement with the blocking group. An example of a useful reducing 
agent is 1-phenyl-3-pyrazolidinone (described in U.S. Pat. No. 4,423,139 
for stabilizing leuco dyes). Masking of such reducing agents during the 
processing step is usually necessary since they may act as developers or 
development accelerators to cause unacceptable fogging. 
Non-limiting representative examples of stabilizer groups A-according to 
the present invention are: 
##STR8## 
Non-limiting examples of protected stabilizers according to the present 
invention are: 
##STR9## 
Photothermographic articles of the invention may contain other 
post-processing stabilizers or stabilizer precursors in combination with 
the compounds of the invention, as well as other additives in combination 
with the compound of the invention such as shelf-life stabilizers, toners, 
development accelerators and other image modifying agents. 
The amounts of the above described stablizer ingredients that are added to 
the emulsion layer according to the present invention may be varied 
depending upon the particular compound used and upon the type of emulsion 
layer (i.e., black and white or color). However, the ingredients are 
preferably added in an amount of 0.01 to 100 mol per mole of silver 
halide, and more preferably from 0.1 to 50 mol per mol of silver halide in 
the emulsion layer. 
The photothermographic dry silver emulsions of this invention may be 
constructed of one or more layers on a substrate. Single layer 
constructions must contain the silver source material, the silver halide, 
the developer and binder as well as any optional additional materials such 
as toners, coating aids, and other adjuvants. Two-layer constructions must 
contain the silver source and silver halide in one emulsion layer (usually 
the layer adjacent to the substrate) and some of the other ingredients in 
the second layer or both layers, although two layer constructions 
comprising a single emulsion layer containing all the ingredients and a 
protective topcoat are envisioned. Multicolor photothermographic dry 
silver constructions may contain sets of these bilayers for each color, or 
they may contain all ingredients within a single layer as described in 
U.S. Pat. No. 4,708,928. In the case of multilayer multicolor 
photothermographic articles the various emulsion layers are generally 
maintained distinct from each other by the use of functional or 
non-functional barrier layers between the various photosensitive layers as 
described in U.S. Pat. No. 4,460,681. 
While not necessary for practice of the present invention, it may be 
advantageous to add mercury (II) salts to the emulsion layer(s) as an 
antifoggant. Preferred mercury (II) salts for this purpose are mercuric 
acetate and mercuric bromide. 
The light sensitive silver halide used in the present invention may 
typically be employed in a range of 0.75 to 25 mol percent and, 
preferably, from 2 to 20 mol percent of organic silver salt. 
The silver halide may be any photosensitive silver halide such as silver 
bromide, silver iodide, silver chloride, silver bromoiodide, silver 
chlorobromoiodide, silver chlorobromide, etc. The silver halide may be in 
any form which is photosensitive including, but not limited to cubic, 
orthrohombic, tabular, tetrahedral, etc., and may have epitaxial growth of 
crystals thereon. 
The silver halide used in the present invention may be employed without 
modification. However, it may be chemically sensitized with a chemical 
sensitizing agent such as a compound containing sulfur, selenium or 
tellurium etc., or a compound containing gold, platinum, palladium, 
rhodium or iridium, etc., a reducing agent such as a tin halide, etc., or 
a combination thereof. The details of these procedures are described in T. 
N. James The Theory of the Photographic Process, Fourth Edition, Chapter 
5, pages 149 to 169. 
The silver halide may be added to the emulsion layer in any fashion which 
places it in catalytic proximity to the silver source. Silver halide and 
the organic silver salt which are separately formed or "preformed" in a 
binder can be mixed prior to use to prepare a coating solution, but it is 
also effective to blend both of them in a ball mill for a long period of 
time. Further, it is effective to use a process which comprises adding a 
halogen-containing compound in the organic silver salt prepared to 
partially convert the silver of the organic silver salt to silver halide. 
Methods of preparing these silver halide and organic silver salts and 
manners of blending them are known in the art and described in Research 
Disclosure, June 1978, item 17029, and U.S. Pat. No. 3,700,458. 
The use of preformed silver halide emulsions of this invention can be 
unwashed or washed to remove soluble salts. In the latter case the soluble 
salts can be removed by chill-setting and leaching or the emulsion can be 
coagulation washed, e.g., by the procedures described in U.S. Pat. Nos. 
2,618,556; 2,614,928; 2,565,418; 3,241,969; and 2,489,341. The silver 
halide grains may have any crystalline habit including, but not limited to 
cubic, tetrahedral, orthorhombic, tabular, laminar, platelet, etc. 
The light-sensitive silver halides may be advantageously spectrally 
sensitized with various known dyes including cyanine, merocyanine, styryl, 
hemicyanine, oxonol, hemioxonol and xanthene dyes. Useful cyanine dyes 
include those having a basic nucleus, such as thiazoline nucleus, an 
oxazoline nucleus, a pyrroline nucleus, a pyridine nucleus, an oxazole 
nucleus, a thiazole nucleus, a selenazole nucleus and an imidazole 
nucleus. Useful merocyanine dyes which are preferred include those having 
not only the above described basic nuclei but also acid nuclei, such as a 
thiohydantoin nucleus, a rhodanine nucleus, an oxazolidinedione nucleus, a 
thiazolidinedione nucleus, a barbituric acid nucleus, a thiazolinone 
nucleus, a malononitrile nucleus and a pyrazolone nucleus. In the above 
described cyanine and merocyanine dyes, those having imino groups or 
carboxyl groups are particularly effective. Practically, the sensitizing 
dyes to be used in the present invention may be properly selected from 
known dyes such as those described in U.S. Pat. Nos. 3,761,279, 3,719,495, 
and 3,877,943, British Pat. Nos. 1,466,201, 1,469,117 and 1,422,057, and 
can be located in the vicinity of the photocatalyst according to known 
methods. Spectral sensitizing dyes may be typically used in amounts of 
about 10.sup.-4 mol to about 1 mol per 1 mol of silver halide. 
The organic silver salt which can be used in the present invention is a 
silver salt which is comparatively stable to light, but forms a silver 
image when heated to 80.degree. C. or higher in the presence of an exposed 
photocatalyst (such as photographic silver halide) and a reducing agent. 
The organic silver salt may be any organic material which contains a 
reducible source of silver ions. Silver salts of organic acids, 
particularly long chain (10 to 30 preferably 15 to 28 carbon atoms) fatty 
carboxylic acids are preferred. Complexes of organic or inorganic silver 
salts wherein the ligand has a gross stability constant between 4.0 and 
10.0 are also desirable. The silver source material should preferably 
constitute from about 5 to 30 percent by weight of the imaging layer. 
Preferred organic silver salts include silver salts of organic compounds 
having a carboxy group. Non-limiting examples thereof include silver salts 
of an aliphatic carboxylic acid and a silver salt of an aromatic 
carboxylic acid Preferred examples of the silver salts of aliphatic 
carboxylic acids include silver behenate, silver stearate, silver oleate, 
silver laurate, silver caproate, silver myristate, silver palmitate, 
silver maleate, silver fumarate, silver tartrate, silver linoleate, silver 
butyrate and silver camphorate, mixtures thereof, etc. Silver salts with a 
halogen atom or a hydroxyl on the aliphatic carboxylic acid can also be 
effectively used. Preferred examples of the silver salts of aromatic 
carboxylic acids and other carboxyl group-containing compounds include 
silver benzoate, a silver substituted benzoate such as silver 
3,5-dihydroxybenzoate, silver o-methylbenzoate, silver m-methylbenzoate, 
silver p-methylbenzoate, silver 2,4-dichlorobenzoate, silver 
acetamido-benzoate, silver p-phenylbenzoate, etc., silver gallate, silver 
tannate, silver phthalate, silver terephthalate, silver salicylate, silver 
phenylacetate, silver pyromellitate, a silver salt of 
3-carboxymethyl-4-methyl-4-thiazoline-2-thione or the like as described in 
U.S. Pat. No. 3,785,830, and silver salt of an aliphatic carboxylic acid 
containing a thioether group as described in U.S. Pat. No. 3,330,663, etc. 
Silver salts of compounds containing mercapto or thione groups and 
derivatives thereof can also be used. Preferred examples of these 
compounds include a silver salt of 3-mercapto-4-phenyl-1,2,4-triazole, a 
silver salt of 2-mercaptobenzimidazole, a silver salt of 
2-mercapto-5-aminothiadiazole, a silver salt of 2-(ethylglycolamido) 
benzothiazole, a silver salt of thioglycolic acid such as a silver salt of 
an S-alkyl thioglycolic acid (wherein the alkyl group has from 12 to 22 
carbon atoms), a silver salt of a dithiocarboxylic acid such as a silver 
salt of dithioacetic acid, a silver salt of a thioamide, a silver salt of 
5-carboxylic-1-methyl-2-phenyl-4-thiopyridine, a silver salt of 
mercaptotriazine, a silver salt of 2-mercaptobenzoxazole, a silver salt as 
described in U.S. Pat. No. 4,123,274, for example, a silver salt of 
1,2,4-mercaptothiazole derivative such as a silver salt of 
3-amino-5-benzylthio-1,2,4-thiazole, a silver salt of thione compound such 
as a silver salt of 3-(2-carboxyethyl)-4-methyl-4-thiazoline-2-thione as 
disclosed in U.S. Pat. No. 3,301,678. 
Furthermore, a silver salt of a compound containing an imino group may be 
used. Preferred examples of these compounds include silver salts of 
benzothiazole and derivatives thereof, for example, silver salts of 
benzothiazoles such as silver methylbenzotriazolate, etc., silver salt of 
halogen-substituted benzotriazoles, such as silver 
5-chlorobenzotriazolate, etc., silver salts of carboimidobenzotriazole, 
etc., silver salt of 1,2,4-triazoles or 1-H-tetrazoles as described in 
U.S. Pat. No. 4,220,709, silver salts of imidazoles and imidazole 
derivatives, and the like. Various silver acetylide compounds can also be 
used, for instance, as described in U.S. Pat. Nos. 4,761,361 and 
4,775,613. 
It is also found convenient to use silver half soaps, of which an equimolar 
blend of silver behenate and behenic acid, prepared by precipitation from 
aqueous solution of the sodium salt of commercial behenic acid and 
analyzing about 14.5 percent silver, represents a preferred example. 
Transparent sheet materials made on transparent film backing require a 
transparent coating and for this purpose the silver behenate full soap, 
containing not more than about four or five percent of free behenic acid 
and analyzing about 25.2 percent silver may be used. 
The method used for making silver soap dispersions is well known in the art 
and is disclosed in Research Disclosure, April 1983, item 22812, Research 
Disclosure, October 1983, item 23419 and U.S. Pat. No. 3,985,565. 
The reducing agent for the organic silver salt may be any material, 
preferably organic material, that can reduce silver ion to metallic 
silver. Conventional photographic developers such as phenidone, 
hydroquinones, and catechol are useful but hindered phenol reducing agents 
are preferred. The reducing agent should be present as 1 to 10 percent by 
weight of the imaging layer. In multilayer constructions, if the reducing 
agent is added to a layer other than an emulsion layer, slightly higher 
proportions, of from about 2 to 15 percent tend to be more desirable. 
A wide range of reducing agents has been disclosed in dry silver systems 
including amidoximes such as phenylamidoxime, 2-thienylamidoxime and 
p-phenoxyphenylamidoxime, azines (e.g., 
4-hydroxy-3,5-dimethoxybenzaldehydeazine); a combination of aliphatic 
carboxylic acid aryl hydrazides and ascorbic acid, such as 
2,2'-bis(hydroxymethyl)propionyl-.beta.-phenylhydrazide in combination 
with ascorbic acid; a combination of polyhydroxybenzene and hydroxylamine, 
a reductone and/or a hydrazine (e.g., a combination of hydroquinone and 
bis(ethoxyethyl)hydroxylamine, piperidinohexose reductone or 
formyl-4-methylphenylhydrazine); hydroxamic acids such as phenylhydroxamic 
acid, p-hydroxyphenylhydroxamic acid, and .beta.-alaninehydroxamic acid; a 
combination of azines and sulfonamidophenols, (e.g., phenothiazine and 
2,6-dichloro-4-benzenesulfonamidophenol); .alpha.-cyanophenylacetic acid 
derivatives such as ethyl-.alpha.-cyano-2-methylphenylacetate, ethyl 
.alpha.-cyanophenylacetate; bis-.beta.-naphthols as illustrated by 
2,2'-dihydroxyl-1,1'-binaphthyl, 
6,6'-dibromo-2,2'-dihydroxy-1,1'-binaphthyl, and 
bis(2-hydroxy-1-naphthyl)methane; a combination of bis-.beta.-naphthol and 
a 1,3-dihydroxybenzene derivative, (e.g., 2,4-dihydroxybenzophenone or 
2,4-dihydroxyacetophenone); 5-pyrazolones such as 
3-methyl-1-phenyl-5-pyrazolone; reductones as illustrated by 
dimethylaminohexose reductone, anhydrodihydroaminohexose reductone, and 
anhydrodihydropiperidonehexose reductone; sulfonamido-phenol reducing 
agents such as 2,6-dichloro-4-benzenesulfonamidophenol, and 
p-benzenesulfonamidophenol; 2-phenylindane-1,3-dione and the like; 
chromans such as 2,2-dimethyl-7-t-butyl-6-hydroxychroman; 
1,4-dihydropyridines such as 
2,6-dimethoxy-3,5-dicarbethoxy-1,4-dihydropyridine; bisphenols (e.g., 
bis(2-hydroxy-3-t-butyl-5-methylphenyl)methane, 
2,2-bis(4-hydroxy-3-methylphenyl)propane, 
4,4-ethylidene-bis(2-t-butyl-6-methylphenol), and 
2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane); ascorbic acid derivatives 
(e.g., 1-ascorbyl palmitate, ascorbyl stearate); and aldehydes and 
ketones, such as benzil and biacetyl; 3-pyrazolidones and certain 
indane-1,3-diones. 
In addition to the aforementioned ingredients it may be advantageous to 
include additives known as "toners" that improve the image. Toner 
materials may be present, for example, in amounts from 0.1 to 10 percent 
by weight of all silver bearing components. Toners are well-known 
materials in the photothermographic art as shown in U.S. Pat. Nos. 
3,080,254; 3,847,612 and 4,123,282. 
Examples of toners include phthalimide and N-hydroxyphthalimide; cyclic 
imides such as succinimide, pyrazoline-5-ones, and quinazolinone, 
3-phenyl-2-pyrazoline-5-one, 1-phenylurazole, quinazoline, and 
2,4-thiazolidinedione; naphthalimides (e.g., N-hydroxy-1,8-naphthalamide); 
cobalt complexes (e.g., cobaltic hexammine trifluoroacetate); mercaptans 
as illustrated by 3-mercapto-1,2,4-triazole, 2,4-dimercaptopyrimidine, 
3-mercapto-4,5-diphenyl-1,2,4-triazole and 
2,5-dimercapto-1,3,4-thiadiazole; N-(aminomethyl)aryldicarboximides, 
(e.g., (N,N-dimethylaminomethyl)-phthalimide, and 
N,N-(dimethylaminomethyl)naphthalene-2,3-dicarboximide); and a combination 
of blocked pyrazoles, isothiuronium derivatives and certain photobleaching 
agents (e.g., a combination of N,N'-hexamethylene 
bis(1-carbamoyl-3,5-dimethylpyrazole), 
1,8-(3,6-diazaoctane)bis(isothiuronium trifluoroacetate) and 
2-(tribromomethylsulfonyl)benzothiazole); and merocyanine dyes such as 
3-ethyl-5[(3-ethyl-2-benzothiasolinylidene)-1-methylethylidene]-2-thio-2,4 
-oxazolidineodine; phthalazinone and phthalazinone derivatives or metal 
salts or these derivatives such as 4-(1-naphthyl)phthalazinone, 
6-chlorophthalazinone, 5,7-dimethoxyphthalazinone, and 
2,3-dihydro-1,4-phthalazinedione; a combination of phthalazinone plus 
phthalic acid derivatives (e.g., phthalic acid, 4-methylphthalic acid, 
4-nitrophthalic acid, and tetrachlorophthalic anhydride); 
quinazolinediones, benzoxazine or naphthoxazine derivatives; rhodium 
complexes functioning not only as tone modifiers, but also as sources of 
halide ion for silver halide formation in situ, such as ammonium 
hexachlororhodate (III), rhodium bromide, rhodium nitrate and potassium 
hexachlororhodate (III); inorganic peroxides and persulfates (e.g., 
ammonium peroxydisulfate and hydrogen peroxide); benzoxazine-2,4-diones 
such as 1,3-benzoxazine-2,4-dione, 8-methyl-1,3-benzoxazine-2,4-dione, and 
6-nitro-1,3-benzoxazine-2,4-dione; pyrimidines and asymmetric triazines 
(e.g., 2,4-dihydroxypyrimidine, 2-hydroxy-4-aminopyrimidine), azauracils, 
and tetrazapentalene derivatives (e.g., 
3,6-dimercapto-1,4-diphenyl-1H,4H-2,3a,5,6a-tetrazapentalene, and 
1,4-di(o-chlorophenyl)-3,6-dimercapto-1H, 4H-2,3a,5,6a-tetrazapentalene). 
A number of methods are known in the art for obtaining color images with 
dry silver systems including: a combination of silver benzotriazole, well 
known magenta, yellow and cyan dye-forming couplers, aminophenol 
developing agents, a base release agent such as guanidinium 
trichloroacetate and silver bromide in poly(vinyl butyral) as described in 
U.S. Pat. Nos. 4,847,188 and 5,064,742; preformed dye release systems such 
as those described in U.S. Pat. No. 4,678,739; a combination of silver 
bromoiodide sulfonamidophenol reducing agent, silver behenate, poly(vinyl 
butyral), an amine such as n-octadecylamine and 2-equivalent or 
4-equivalent cyan, magenta or yellow dye-forming couplers; leuco dye bases 
which oxidize to form a dye image (e.g., Malachite Green, Crystal Violet 
and para-rosaniline); a combination of in situ silver halide, silver 
behenate, 3-methyl-1-phenylpyrazolone and N,N'-dimethyl-p-phenylenediamine 
hydrochloride; incorporating phenolic leuco dye reducing agents such as 
2(3,5-di-(t-butyl)-4-hydroxyphenyl)-4,5-diphenylimidazole, and 
bis(3,5-di-(t-butyl)-4-hydroxyphenyl)phenylmethane, incorporating 
azomethine dyes or azo dye reducing agents; silver dye bleach processes 
(for example, an element comprising silver behenate, behenic acid, 
poly(vinyl butyral), poly(vinyl-butyral) peptized silver bromoiodide 
emulsion, 2,6-dichloro-4-benzenesulfonamidophenol, 
1,8-(3,6-diazaoctane)bis(isothiuronium-p-toluenesulfonate) and an azo dye 
can be exposed and heat processed to obtain a negative silver image with a 
uniform distribution of dye, and then laminated to an acid activator sheet 
comprising polyacrylic acid, thiourea and p-toluenesulfonic acid and 
heated to obtain well defined positive dye images); and amines such as 
aminoacetanilide (yellow dye-forming), 3,3'-dimethoxybenzidine (blue 
dye-forming) or sulfanilide (magenta dye forming) that react with the 
oxidized form of incorporated reducing agents such as 
2,6-dichloro-4-benzenesulfonamidophenol to form dye images. Neutral dye 
images can be obtained by the addition of amines such as behenylamine and 
p-anisidine. 
Leuco dye oxidation in such silver halide systems for color formation is 
disclosed in U.S. Pat. Nos. 4,021,240, 4,374,821, 4,460,681 and 4,883,747. 
Representative classes of leuco dyes that are suitable for use in the 
present invention include, but are not limited to, bisphenol and 
bisnaphthol leuco dyes, phenolic leuco dyes, indoaniline leuco dyes, 
imidazole leuco dyes, azine leuco dyes, oxazine leuco dyes, diazine leuco 
dyes, and thiazine leuco dyes. Preferred classes of dyes are described in 
U.S. Pat. Nos. 4,460,681 and 4,594,307. 
One class of leuco dyes useful in this invention are those derived from 
imidazole dyes. Imidazole leuco dyes are described in U.S. Pat. No. 
3,985,565. 
Another class of leuco dyes useful in this invention are those derived from 
so-called "chromogenic dyes." These dyes are prepared by oxidative 
coupling of a p-phenylenediamine with a phenolic or anilinic compound. 
Leuco dyes of this class are described in U.S. Pat. No. 4,594,307. Leuco 
chromogenic dyes having short chain carbamoyl protecting groups are 
described in assignee's copending application U.S. Ser. No. 07/939,093, 
incorporated herein by reference. 
A third class of dyes useful in this invention are "aldazine" and 
"ketazine" dyes. Dyes of this type are described in U.S. Pat. Nos. 
4,587,211 and 4,795,697. 
Another preferred class of leuco dyes are reduced forms of dyes having a 
diazine, oxazine, or thiazine nucleus. Leuco dyes of this type can be 
prepared by reduction and acylation of the color-bearing dye form. Methods 
of preparing leuco dyes of this type are described in Japanese Patent No. 
52-89131 and U.S. Pat. Nos. 2,784,186; 4,439,280; 4,563,415, 4,570,171, 
4,622,395, and 4,647,525, all of which are incorporated herein by 
reference. 
Another class of dye releasing materials that form a dye upon oxidation are 
known as preformed-dye-release (PDR) or redox-dye-release (RDR) materials. 
In these materials the reducing agent for the organic silver compound 
releases a pre-formed dye upon oxidation. Examples of these materials are 
disclosed in Swain, U.S. Pat. No. 4,981,775, incorporated herein by 
reference. 
The optional leuco dyes of this invention, can be prepared as described in 
H. A. Lubs The Chemistry of Synthetic Dyes and Pigments; Hafner; New York, 
NY; 1955 Chapter 5; in H. Zollinger Color Chemistry: Synthesis, Properties 
and Applications of Organic Dyes and Pigments; VCH; New York, N.Y.; pp. 
67-73, 1987, and in U.S. Pat. No. 5,149,807; and EPO Laid Open Application 
No. 0,244,399. 
Silver halide emulsions containing the stabilizers of this invention can be 
protected further against the additional production of fog and can be 
stabilized against loss of sensitivity during shelf storage. Suitable 
antifoggants, stabilizers, and stabilizer precursors which can be used 
alone or in combination, include thiazolium salts as described in U.S. 
Pat. Nos. 2,131,038 and 2,694,716; azaindenes as described in U.S. Pat. 
Nos. 2,886,437 and 2,444,605; mercury salts as described in U.S. Pat. No. 
2,728,663; urazoles as described in U.S. Pat. No. 3,287,135; 
sulfocatechols as described in U.S. Pat. No. 3,235,652; oximes as 
described in British Patent No. 623,448; nitrones; nitroindazoles; 
polyvalent metal salts as described in U.S. Pat. No. 2,839,405; 
thiouronium salts as described in U.S. Pat. No. 3,220,839; and palladium, 
platinum and gold salts described in U.S. Pat. Nos. 2,566,263 and 
2,597,915; halogen-substituted organic compounds as described in U.S. Pat. 
Nos. 4,108,665 and 4,442,202; triazines as described in U.S. Pat. Nos. 
4,128,557; 4,137,079; 4,138,265; and 4,459,350; and phosphorous compounds 
as described in U.S. Pat. No. 4,411,985. 
Stabilized emulsions of the invention can contain plasticizers and 
lubricants such as polyalcohols (e.g., glycerin and diols of the type 
described in U.S. Pat. No. 2,960,404); fatty acids or esters such as those 
described in U.S. Pat. No. 2,588,765 and U.S. Pat. No. 3,121,060; and 
silicone resins such as those described in British Patent No. 955,061. 
The photothermographic elements of the present invention may include image 
dye stabilizers. Such image dye stabilizers are illustrated by British 
Patent No. 1,326,889; U.S. Pat. Nos. 3,432,300; 3,698,909; 3,574,627; 
3,573,050; 3,764,337 and 4,042,394. 
Photothermographic elements containing emulsion layers stabilized according 
to the present invention can be used in photographic elements which 
contain light absorbing materials and filter dyes such as those described 
in U.S. Pat. Nos. 3,253,921; 2,274,782; 2,527,583 and 2,956,879. If 
desired, the dyes can be mordanted, for example, as described in U.S. Pat. 
No. 3,282,699. 
Photothermographic elements containing emulsion layers stabilized as 
described herein can contain matting agents such as starch, titanium 
dioxide, zinc oxide, silica, polymeric beads including beads of the type 
described in U.S. Pat. No. 2,992,101 and U.S. Pat. No. 2,701,245. 
Emulsions stabilized in accordance with this invention can be used in 
photothermographic elements which contain antistatic or conducting layers, 
such as layers that comprise soluble salts (e.g., chlorides, nitrates, 
etc.), evaporated metal layers, ionic polymers such as those described in 
U.S. Pat. Nos. 2,861,056 and 3,206,312 or insoluble inorganic salts such 
as those described in U.S. Pat. No. 3,428,451. 
The binder may be selected from any of the well-known natural or synthetic 
resins such as gelatin, polyvinyl acetals, polyvinyl chloride, polyvinyl 
acetate, cellulose acetate, polyolefins, polyesters, polystyrene, 
polyacrylonitrile, polycarbonates, and the like. Copolymers and 
terpolymers are of course included in these definitions. The preferred 
photothermographic silver containing polymers are polyvinyl butyral, butyl 
ethyl cellulose, methacrylate copolymers, maleic anhydride ester 
copolymers, polystyrene, and butadiene-styrene copolymers. 
Optionally, these polymers may be used in combinations of two or more 
thereof. Such a polymer is used in an amount sufficient to carry the 
components dispersed therein, that is, within the effective range of the 
action as the binder. The effective range can be appropriately determined 
by one skilled in the art. As a guide in the case of carrying at least an 
organic silver salt, it can be said that a preferable ratio of the binder 
to the organic silver salt ranges from 15:1 to 1:2, and particularly from 
8:1 to 1:1. 
Photothermographic emulsions containing a stabilizer according to the 
present invention may be coated on a wide variety of supports. Typical 
supports include polyester film, subbed polyester film, poly(ethylene 
terephthalate)film, cellulose nitrate film, cellulose ester film, 
poly(vinyl acetal) film, polycarbonate film and related or resinous 
materials, as well as glass, paper metal and the like. Typically, a 
flexible support is employed, especially a paper support, which may be 
partially acetylated or coated with baryta and/or an .alpha.-olefin 
polymer, particularly a polymer of an .alpha.-olefin containing 2 to 10 
carbon atoms such as polyethylene, polypropylene, ethylene-butene 
copolymers and the like. Substrates may be transparent or opaque. 
Substrates with a backside resistive heating layer may also be used in 
color photothermographic imaging systems such as shown in U.S. Pat. Nos. 
4,460,681 and 4,374,921. 
Photothermographic emulsions of this invention can be coated by various 
coating procedures including dip coating, air knife coating, curtain 
coating, or extrusion coating using hoppers of the type described in U.S. 
Pat. No. 2,681,294. If desired, two or more layers may be coated 
simultaneously by the procedures described in U.S. Pat. No. 2,761,791 and 
British Patent No. 837,095. 
Additional layers may be incorporated into photothermographic articles of 
the present invention such as dye receptive layers for receiving a mobile 
dye image, an opacifying layer when reflection prints are desired, a 
protective topcoat layer and a primer layer as is known in the 
photothermographic art. Additionally, it may be desirable in some 
instances to coat different emulsion layers on both sides of a transparent 
substrate, especially when it is desirable to isolate the imaging 
chemistries of the different emulsion layers. 
The present invention will be illustrated in detail in the following 
examples, but the embodiment of the present invention is not limited 
thereto. 
EXAMPLES 
These examples provide exemplary synthetic procedures for compounds of the 
invention. Photothermographic imaging constructions are shown. The scope 
of the invention is not to be limited to the specific examples. 
All materials used in the following examples were readily available from 
standard commercial sources such as Aldrich Chemical Co. (Milwaukee, Wis.) 
unless otherwise specified. The following additional terms and materials 
were used. 
Acryloid.TM. B-66 is a poly(methyl methacrylate) available from Rohm and 
Haas. 
Airvol.TM. 523 is a poly(vinyl alcohol) available from Air Products. 
Butvar.TM. B-76 is a poly(vinyl butyral) available from Monsanto Company, 
St. Louis, Mo.) 
HgC.sub.2 H.sub.3 O.sub.2 is mercuric acetate 
MEK is methyl ethyl ketone (2-butanone). 
PAZ is 1-(2H)-phthalazinone 
PET is poly(ethylene terephthalate) 
PVP K-90 is a poly(vinyl pyrrolidone) available from International 
Specialty Products. 
Styron.TM. 685 is a polystyrene resin available from Dow Chemical Company. 
VAGH.TM. is a vinyl chloride/vinyl acetate copolymer available from Union 
Carbide Corp. 
Dye A is disclosed in U.S. Pat. No. 4,476,220 and has the following 
formula: 
##STR10## 
Dye B is disclosed in U.S. Pat. No. 4,123,282 and has the following 
formula: 
##STR11## 
Dye C is a leuco yellow dye disclosed in U.S. Pat. No. 4,923,792 and has 
the following formula: 
##STR12## 
"Ethyl ketazine" is a leuco magenta dye disclosed in U.S. Pat. No. 
4,795,697 and has the following formula: 
##STR13## 
The following procedure is representative of the method of preparation of 
the stabilizers of the instant invention. 
Preparation of Compound 1: To a solution of methylamine hydrochloride 
(202.6 g, 3.0 mol) and acetone (242 mL, 3.3 mol) in water (500 mL) was 
added a solution of sodium cyanide (147 g, 3.0 mol) in water (400 mL) 
dropwise with stirring. The temperature of the reaction mixture was kept 
below 45.degree. C. by occasional cooling with an ice bath. When addition 
was complete, the reaction mixture was left at room temperature overnight. 
The mixture was then stirred and cooled to 5.degree. C. while acryloyl 
chloride (244 mL, 3.0 mol) and an aqueous solution of sodium hydroxide 
(120 g, 3.0 mol, in 150 mL of water) were added separately and 
simultaneously. The temperature of the reaction mixture was kept below 
10.degree. C. during the addition. When addition was complete, the 
reaction mixture was stirred an additional 4 hr. Ethyl acetate (500 mL) 
was then added, the layers separated, and the aqueous layer extracted with 
2 additional portions of ethyl acetate (500 mL). The organic layers were 
combined, washed successively with saturated aqueous solutions of sodium 
bicarbonate and sodium chloride (200 mL each). The solution was dried over 
anhydrous magnesium sulfate, filtered, and solvent evaporated to afford 
N-acryloyl-N-methyl-2-aminoisobutyronitrile (397 g) as a yellow oil which 
crystallized on standing. 
A mixture of benzimidazole (23.6 g, 0.20 mol) and 
N-acryloyl-N-methyl-2-aminoisobutyronitrile (30.4 g, 0.20 mol) were heated 
neat at 100.degree. C. overnight and the product recrystallized from water 
containing a small amount of ethanol. Spectral analysis confirmed the 
identity of the product as Compound 1. 
Preparation of Compound 11: A mixture of theophylline (28.6 g, 0.16 mol), 
N-acryloyl-N-methyl-2-aminoisobutyronitrile (24.1 g, 0.16 mol) and 
1,8-diazabicyclo[5.4.0]undec-7-ene (75 mg, 0.50 mmol) was heated at 
100.degree. C. for 4 days. The product was recrystallized from aqueous 
ethanol. Spectral analysis confirmed the product as Compound 11. 
Evaluation of Stabilizers 
Densitometry measurements were made on a custom built computer scanned 
densitometer and are believed to be comparable to measurements obtainable 
from commercially available densitometers. 
The following definitions are used in the sensitometry measurements. 
Spd.sub.2 is the log exposure corresponding to a density of 0.60 above Dmin 
Toe.sub.2 is the slope of the line joining the density points at 0.50 log E 
and 0.25 log E before the log E value corresponding to a density of 0.30 
above Dmin. 
AC.sub.2 is the slope of the line joining the density points of 0.60 and 
1.20 above Dmin. 
The Green filter used was a Wratten #58. 
The Blue filter used was a Wratten #47B. 
EXAMPLE 1 
The following ingredients were mixed in a pint jar: 
______________________________________ 
Silver Soap 3.0410 g 
Toluene 24.6318 g 
Acetone 2.7369 g 
Butvar .TM. B-76 
0.0242 g 
______________________________________ 
The resulting dispersion was homogenized. Using a metal stirring rod, the 
following ingredients were added to the dispersion with stirring in the 
order listed: 
______________________________________ 
Material Amount 
______________________________________ 
HgC.sub.2 H.sub.3 O.sub.2 
0.0299 g 
Methanol 0.5913 g 
CaBr.sub.2.2H.sub.2 O 
0.0334 g 
Ethanol 1.0010 g 
CaBr.sub.2.2H.sub.2 O 
0.0334 g 
Ethanol 1.0010 g 
Butvar .TM. B-76 
4.0193 g 
______________________________________ 
The following ingredients were combined in a 4 ounce jar, and upon 
dissolving were added to the above dispersion: 
______________________________________ 
Ethyl Ketazine 0.6090 g 
Phthalazinone 0.9157 g 
Tetrahydrofuran 44.1606 g 
2-butanone 4.4161 g 
Union Carbide VAGH .TM. 
2.2063 g 
Butvar .TM. B-76 9.3879 g 
Dye A 0.0006 g 
Ethanol 1.1608 g 
______________________________________ 
To 10.0 g of the resulting mixture, the following were added: 
A. Nothing. This sample contains no stabilizer and serves as a control. 
B. 0.0732 g of stabilizer Compound 1 in 1.00 mL methanol 
C. 0.105 g of stabilizer Compound 7 in 1.00 mL methanol 
D. 0.040 g of stabilizer Compound 11 in 2.00 mL methanol 
The first and second coatings were applied simultaneously at 2.0 mil (0.05 
mm) wet thickness each. The web was then dried for 5 minutes at 
180.degree. F. (82.2.degree. C.). 
Samples from the coating were exposed to an EG&G sensitometer for 10.sup.-3 
seconds through a Wratten 58 green filter and a 0-3 continuous density 
wedge. The samples were then processed for approximately six seconds by 
heating at 135.degree. C. 
The following sensitometric data were obtained from the sample: 
______________________________________ 
Sample 
ID Filter Dmin Dmax Spd.sub.2 
Toe.sub.2 
AC.sub.2 
______________________________________ 
A Green 0.10 1.96 2.22 0.81 2.29 
Blue 0.10 1.03 2.20 0.67 -- 
B Green 0.14 1.35 2.66 0.69 0.61 
Blue 0.12 0.59 -- 0.46 -- 
C Green 0.13 0.95 3.07 0.83 -- 
Blue 0.13 0.47 -- 0.61 -- 
D Green 0.10 1.78 2.45 0.83 1.86 
Blue 0.10 0.93 2.35 0.60 -- 
______________________________________ 
Post-processing stability was measured by exposing the samples to 1200 
foot-candles of light for 48 hours at 65% relative humidity and 27.degree. 
C. The absolute Dmin measurements following this test were: 
______________________________________ 
Filter A B C D 
______________________________________ 
Green 0.39 0.19 0.22 0.31 
Blue 0.54 0.21 0.25 0.39 
______________________________________ 
EXAMPLE 2 
To 10.0 g of a silver soap dispersion prepared as in Example 1 above, were 
added: 
E. Nothing. This sample contains no stabilizer and serves as a control. 
F. 0.0656 g of stabilizer compound 2 in 1.00 mL methanol 
A second coating solution comprised the following ingredients: 
______________________________________ 
Toluene 36.0 g 
2-butanone 36.0 g 
Stryon .TM. 685 24.67 g 
Acryloid .TM. B-66 
3.33 g 
______________________________________ 
The first and second coatings were applied simultaneously at 2.0 mil (50.8 
.mu.m) wet thickness each. The web was then dried for five minutes at 
180.degree. F. (82.degree. C.). 
Samples from the coating were exposed to an EG&G sensitometer for 10.sup.-3 
seconds through a Wratten 58 green filter and 0-3 continuous density 
wedge. The samples were then processed for approximately six seconds at 
135.degree. C. in a 3M Model 9014 Hot Roll Processor. The following 
sensitometric data were obtained from the sample: 
______________________________________ 
Sample 
ID Filter Dmin Dmax Spd.sub.2 
Toe.sub.2 
AC.sub.2 
______________________________________ 
E Green 0.11 1.72 2.07 0.71 1.38 
Blue 0.12 0.92 2.26 0.50 -- 
F Green 0.58 1.79 2.07 0.57 1.38 
Blue 0.36 0.94 -- 0.40 -- 
______________________________________ 
Post Processing Stability was measured by exposing the samples to 1200 
foot-candles of light for 24 hours at 65% relative humidity and 27.degree. 
C. The absolute Dmin measurements following this test were: 
______________________________________ 
Filter E F 
______________________________________ 
Green 0.26 0.38 
Blue 0.33 0.33 
______________________________________ 
EXAMPLE 3 
The following ingredients were mixed in a pint jar: 
______________________________________ 
Silver Soap 
2.1540 g 
Toluene 17.4472 g 
Acetone 1.9386 g 
______________________________________ 
The resulting dispersion was homogenized. Using a metal stirring rod, the 
following ingredients were added to the dispersion: 
______________________________________ 
2-butanone 13.5553 g 
Isopropanol 18.5531 g 
Butvar B-76 0.0663 g 
______________________________________ 
______________________________________ 
Material Amount 
______________________________________ 
Pyridine 0.0161 g 
2-butanone 0.1161 g 
HgBr.sub.2 0.0235 g 
Ethanol 0.3395 g 
CaBr.sub.2.2H.sub.2 O 
0.0308 g 
Ethanol 0.9167 g 
PVP K-90 3.6078 g 
Butvar B-76 4.0193 g 
______________________________________ 
To the resulting dispersion the following were added: 
______________________________________ 
Dye B 0.0019 g 
Toluene 
1.1059 g 
Ethanol 
3.3177 g 
______________________________________ 
After 30 minutes, the following ingredients were added to a glass jar, and 
upon dissolving, were added to 67.7003 g of the silver premix: 
______________________________________ 
Tribenzylamine 0.6703 g 
Phthalazinone 0.1959 g 
Ethanol 15.3136 g 
2-butanone 15.3136 g 
Dye-C 0.8063 g 
______________________________________ 
To 9.90 g of the resulting mixture, the following were added: 
G. Nothing. This sample contains no stabilizer and serves as a control. 
H. 0.100 g of stabilizer Compound 9 in 0.500 mL tetrahydrofuran and 0.500 
mL methanol 
J. 0.201 g of stabilizer Compound 9 in 0.500 mL tetrahydrofuran and 0.500 
mL methanol 
K. 0.105 g of stabilizer Compound 7 in 0.500 mL tetrahydrofuran and 0.500 
mL methanol 
L. 0.210 g of stabilizer Compound 7 in 0.500 mL tetrahydrofuran and 0.500 
mL methanol 
The samples were coated at 2.9 mil (73.7 micrometers) wet thickness and 
dried 4.5 minutes at 180.degree. F. (82.2.degree. C.). 
A second coating solution was prepared in the following manner: 
______________________________________ 
Airvol .TM. 523 51.1407 g 
Water 324.8546 g 
______________________________________ 
The suspension was stirred with heating until the polymer was fully 
dissolved. The resulting solution was cooled to below 40.degree. C. and 
the following were added: 
______________________________________ 
Methanol 305.4030 g 
Phthalazine 0.4179 g 
Benzotriazole 0.0056 g 
Tetrachlorophthalic 
0.4298 g 
anhydride 
Methanol 9.4752 g 
Sodium Acetate 2.4500 g 
______________________________________ 
The resulting solution was then coated at 3.8 mils wet and dried 4.5 
minutes at 180.degree. F. (82.2.degree. C.). 
Samples from the coating were exposed to an EG&G sensitometer for 10.sup.-3 
seconds through Wratten 47B blue filter and 0-3 continuous density wedge. 
The exposed strips were processed for approximately six seconds in a 3M 
Model 9014 Hot Roll Processor. The following sensitometry was obtained 
from the samples: 
______________________________________ 
Sample 
ID Filter Dmin Dmax Spd2 Toe2 AC2 
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G Blue 0.07 2.45 2.14 0.83 6.31 
H Blue 0.08 2.48 2.18 0.85 7.42 
J Blue 0.08 2.20 2.33 0.90 6.74 
K Blue 0.08 2.49 2.02 0.86 7.61 
L Blue 0.07 2.35 2.09 0.93 6.72 
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Post Processing Stability was measured by exposing the samples to 100 
foot-candles of light for 7 days at 80% relative humidity and 27.degree. 
C. The absolute Dmin measurements following this test were: 
______________________________________ 
Sample ID 
Dmin 
______________________________________ 
G 1.10 
H 0.75 
J 0.69 
K 0.49 
L 0.37 
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