PHOTOGRAPHIC AND THERMOGRAPHIC MATERIAL CONTAINING A RESORCINOL DYE-FORMING COUPLER

PRODUIT PHOTOGRAPHIQUE ET THERMOGRAPHIQUE, CONTENANT DU RESORCINOL COMME AGENT DE COUPLAGE AVEC FORMATION DE COULEUR

English Abstract

Abstract of the Disclosure
A heat developable photographic element for
producing a dye enhanced silver image comprises, in reactive
association, (a) photosensitive silver halide, (b) an
image-forming combination comprising (i) an organic silver
salt oxidizing agent, with (ii) an organic reducing agent,
(c) a resorcinol, dye-forming coupler that forms a dye with
the oxidized form of the reducing agent and (d) a binder.
After imagewise exposure, a dye enhanced silver image can be
produced in such a material by merely heating the
material. The combination of the described organic silver
salt oxidizing agent with the organic reducing agent and
the resorcinol, dye-forming coupler can be useful in a
thermographic material. Other addenda employed in heat
developable photographic materials, such as sensitizing dyes,
can be useful with the heat developable materials containing
the resorcinol, dye-forming coupler.

Claims

WHAT IS CLAIMED IS:
1. In a heat developable photographic element
for producing a dye enhanced silver image, comprising a
support having thereon, in reactive association, in binder:
(a) photosensitive silver halide, (b) an image-forming
combination comprising (i) an organic, silver salt oxidizing
agent, with (ii) an organic reducing agent for said silver
salt oxidizing agent, the improvement wherein said element
comprises (c) a resorcinol, dye-forming coupler that forms
a dye imagewise with the oxidized form of said reducing
agent, and wherein said element forms a neutral or nearly
neutral appearing image upon imagewise exposure and thermal
processing.
2. A heat developable photographic element as
in Claim 1 wherein said binder consists essentially of a
gelatino binder.
3. A heat developable photographic element as
in Claim 1 comprising about 0.1 to about 1.0 mole of said
coupler per mole of said silver salt oxidizing agent.
4. A heat developable photographic element as
in Claim 1 wherein said coupler consists essentially of a
resorcinol compound represented by the formula:
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wherein
R1 is hydrogen, <IMG>, <IMG>, <IMG>, or <IMG>;
R2 is hydrogen, <IMG>, <IMG> , or <IMG> ;
R3 is hydrogen, <IMG>, or <IMG>;
R4 is hydrogen, <IMG>, <IMG> or
<IMG> ;
R5 is haloalkyl containing 1 to 3 carbon atoms,
CH2OCH3, CH2SR7, NHR8, C2H4COOH, CH-CH2,
NHC2H4Cl, alkyl containing 1 to 20 carbon atoms,
or phenyl;
R6 is OH, NH2, NHCH2CH2OH, or NH?C6H5?OC5H11n;
R7 is alkyl containing 1 to 5 carbon atoms, or phenyl;
and,
R8 is hydrogen, haloalkyl containing 1 to 3 carbon
atoms, CH2OCH3, or C2H4COOH.
5. A heat developable photographic element
as in Claim 1 wherein said coupler consists essentially of
a compound represented by the formula
<IMG>
wherein R5 is haloalkyl containing 1 to 3 carbon atoms,
CH2OCH3, CH2SR7, NHR8, C2H4COOH, CH=CH2, NHC2H4Cl, alkyl
containing 1 to 10 carbon atoms or phenyl; R7 is alkyl
containing 1 to 5 carbon atoms or phenyl; and, R8 is hydrogen,
haloalkyl containing 1 to 3 carbon atoms, CH2OCH3 or C2H4COOH.
- 81 -

6. A heat developable photographic element as in
Claim 1 wherein said coupler consists essentially of 2,6-
dihydroxyacetanilide.
7. A heat developable photographic element as in
Claim 1 wherein said coupler consists essentially of 2',6'-
dihydroxytrifluoroacetanilide.
8. A heat developable photographic element as in
Claim 1 wherein said coupler consists essentially of an
acetanilide represented by the formula:
<IMG>
9. A heat developable photographic element as in
Claim 1 wherein said silver halide consists essentially of a
photographic silver halide gelatino emulsion.
10. A heat developable photographic element as in
Claim 1 wherein said reducing agent consists essentially of
a p-phenylenediamine silver halide developing agent that
exhibits a half wave potential value in aqueous solution at
pH 10 within the range of minus 25 to plus 175 millivolts
versus a saturated calomel electrode.
11. A heat developable photographic element as in
Claim 1 also comprising a heat sensitive base-release agent.
12. A heat developable photographic element as in
Claim 1 also comprising a heat sensitive base-release agent
comprising an aminimide base-release agent.
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13. A heat developable photographic element as in
Claim 1 wherein said oxidizing agent consists essentially of
a silver salt of a 1,2,4-mercaptotriazole derivative repre-
sented by the formula:
<IMG>
wherein Y is aryl containing 6 to 12 carbon atoms; n is an integer from 0 to
2; and Z is hydrogen, hydroxyl or amine.
14. A heat developable photographic element as in
Claim 1 wherein said oxidizing agent is a silver salt of
3-amino-5-benzylthio-1,2,4-triazole.
15. A heat developable photographic element for
producing a dye enhanced silver image comprising a support
having thereon, in reactive association, in a gelatino binder:
(a) a photographic silver halide gelatino emulsion,
(b) an image-forming combination comprising
(i) a silver salt of a 1,2,4-mercaptotriazole
derivative represented by the formula:
<IMG>
wherein Y is aryl containing 6 to 12 carbon
atoms; n is an integer from 0 to 2; and Z is hydrogen,
hydroxyl, or amine, and
(ii) an organic reducing agent for said silver
salt in (b)(i);
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(c) a resorcinol, dye-forming coupler that forms
a dye imagewise with the oxidized form of said
reducing agent.
16. A heat developable photographic element for
providing a dye enhanced, silver image comprising a support
having thereon, in reactive association, in a polymeric
binder:
(a) a photographic silver halide gelatino emulsion,
(b) an image-forming combination comprising
(i) a silver salt of 3-amino-5-benzylthio-
1,2,4-triazole, with
(ii) an organic reducing agent consisting
essentially of 4-amino-2-methoxy-N,N,5-
trimethylaniline sulfate which is a
reducing agent for said silver salt in
(b)(i), and
(c) a coupler consisting essentially of 2',6'-
dihydroxytrifluoroacetanilide.
17. A heat developable photographic element for
providing a dye enhanced, silver image comprising a support
having thereon, in reactive association, in a polymeric
binder:
(a) photosensitive silver halide,
(b) an image-forming combination comprising
(i) a complex of silver with a nitrogen
acid, with
(ii) an organic reducing agent for said
complex of silver with a nitrogen acid,
and
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(c) a resorcinol, dye-forming coupler that forms
a dye with the oxidized form of said reducing
agent.
18. A heat developable photographic element for
producing a dye enhanced silver image comprising a support
having thereon, in reactive association, in a gelatino
binder:
(a) a photosensitive silver halide gelatino
emulsion,
(b) an image-forming combination comprising
(i) a complex of silver with a nitrogen acid
which is a compound selected from the
group consisting of imidazole, pyrazole,
urazole, 1,2,4-triazole and 1H-tetrazole
nitrogen acids and combinations thereof,
and
(ii) an organic reducing agent for said complex
of silver in (b)(i), said reducing agent
consisting essentially of a p-phenylene-
diamine silver halide developing agent
that exhibits an E value in aqueous solu-
tion at pH 10 within the range of minus 25
to plus 175 millivolts versus a saturated
calomel electrode, and
(c) a resorcinol, dye-forming coupler that forms a
dye with the oxidized form of said reducing agent
and consists essentially of a compound
represented by the formula:
<IMG>
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wherein R5 is haloalkyl containing 1 to 3
carbon atoms, CH2OCH3, CH2SR7, NHR8, C2H4COOH,
CH=CH2, NHC2H4Cl, alkyl containing 1 to 10
carbon atoms or phenyl; R7 is alkyl containing
1 to 5 carbon atoms or phenyl; and, R8 is hydrogen,
haloalkyl containing 1 to 3 carbon atoms,
CH2OCH3 or C2H4COOH.
19. A heat developable photographic element for
providing a dye enhanced, silver image comprising a support
having thereon, in reactive association, in a polymeric
binder:
(a) a photosensitive silver halide gelatino
emulsion,
(b) an image-forming combination comprising
(i) a complex of silver with imidazole, with
(ii) an organic reducing agent for said complex
of silver with imidazole, and
(c) a resorcinol, dye-forming coupler that forms
a dye with the oxidized form of said reducing
agent.
20. A heat developable photographic element for
producing a dye enhanced silver image comprising a support
having thereon, in reactive association, in a gelatino
binder:
(a) photosensitive silver halide gelatino emulsion,
(b) an image-forming combination comprising
(i) a complex of silver with dodecyltetrazole,
with,
(ii) an organic reducing agent consisting
essentially of 2-methyl-4-(N-ethyl-N-
- 86 -

hydroxyethyl)-aminoaniline hydrogen
sulfate which is a reducing agent for
said complex of silver in (b)(i),
(c) a coupler consisting essentially of 2',6'-
dihydroxytrifluoroacetanilide, and
(d) a melt-forming compound.
21. A heat developable photographic element for
providing a dye enhanced silver image comprising a support
having thereon, in reactive association, in a polymeric
binder:
(a) photosensitive silver halide,
(b) an image-forming combination comprising
(i) a silver salt of a heterocyclic thione
represented by the formula:
<IMG>
wherein Z' is alkylene containing 1 to 1
carbon atoms; R represents the atoms
necessary to complete a heterocyclic nucleus
selected from carbon, oxygen, sulfur
and nitrogen atoms, with
(ii) an organic reducing agent for said silver
salt of a heterocyclic thione, and
(c) a resorcinol, dye-forming coupler that forms
a dye with the oxidized form of said reducing
agent.
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22. A heat developable photographic element for
providing a dye enhanced silver image comprising a support
having thereon, in reactive association, in a polymeric
binder:
(a) photosensitive silver halide,
(b) an image-forming combination comprising
(i) a silver salt of 3-carboxymethyl-4-
methyl-4-thiazoline-2-thione, with
(ii) an organic reducing agent consisting
essentially of 4-amino-2-methoxy-N,N,5-
trimethylaniline sulfate which is a
reducing agent for said silver salt in
(b)(i), and
(c) a coupler consisting essentially of 2',6'-
dihydroxytrifluoroacetanilide.
23. In a heat developable photographic composition
for providing a dye enhanced silver image comprising, in a
polymeric binder:
(a) photosensitive silver halide,
(b) an image-forming combination comprising
(i) an organic silver salt oxidizing agent,
with
(ii) an organic reducing agent for said silver
salt oxidizing agent,
the improvement wherein said composition comprises
(c) a resorcinol, dye-forming coupler that forms
a dye with the oxidized form of said reducing
agent, and wherein said composition forms a
neutral or nearly neutral appearing image
upon imagewise exposure and thermal proces-
sing.
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24. A heat developable photographic composition
as in Claim 23 wherein said binder consists essentially of
a gelatino binder.
25. A heat developable photographic composition
as in Claim 23 comprising about 0.1 to about 1.0 mole of said
coupler per mole of said silver salt oxidizing agent.
26. A heat developable photographic composition
as in Claim 23 wherein said coupler consists essentially of
a compound represented by the formula:
<IMG>
wherein R5 is haloalkyl containing 1 to 3 carbon atoms,
CH2OCH3, CH2SR7, NHR8, C2H4COOH, CH=CH2, NHC2H4Cl, alkyl
containing 1 to 10 carbon atoms or phenyl; R7 is alkyl
containing 1 to 5 carbon atoms or phenyl; and, R8 is hydrogen,
haloalkyl containing 1 to 3 carbon atoms, CH2OCH3 or C2H4COOH.
27. A heat developable photographic composition
as in Claim 23 wherein said coupler consists essentially of
2,6-dihydroxyacetanilide.
28. A heat developable photographic composition
as in Claim 23 wherein said coupler consists essentially of
2',6'-dihydroxytrifluoroacetanilide.
29. A heat developable photographic composition
as in Claim 23 wherein said coupler consists essentially of
a compound represented by the formula:
- 89 -

<IMG>
30. A heat developable photographic composition
as in Claim 23 wherein said (a) consists essentially of a
photographic silver halide gelatino emulsion.
31. A heat developable photographic composition
as in Claim 23 wherein said reducing agent is a p-phenylene-
diamine silver halide developing agent that exhibits an E
value in aqueous solution at pH 10 within the range of minus
25 to plus 175 millivolts versus a saturated calomel elec-
trode.
32. A heat developable photographic composition
as in Claim 23 also comprising a heat sensitive base-release
agent.
33. A heat developable photographic composition
as in Claim 23 also comprising a heat sensitive base-release
agent comprising an aminimide base-release agent.
34. A heat developable photographic composition
as in Claim 23 wherein the organic silver salt oxidizing
agent consists essentially of a silver salt of a 1,2,4-
mercaptotriazole derivative represented by the formula:
<IMG>
wherein Y is aryl containing 6 to 12 carbon atoms; n is an integer from 0 to 2;
and Z is hydrogen, hydroxyl or amine.
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35. A heat developable photographic composition
as in Claim 23 wherein the organic silver salt oxidizing
agent consists essentially of a silver salt of 3-amino-5-
benzylthio-1,2,4-triazole.
36. A heat developable photographic composition
for providing a dye enhanced silver image comprising, in a
polymeric binder:
(a) a photographic silver halide gelatino
emulsion,
(b) an image-forming combination comprising
(i) a silver salt of 3-amino-5-benzylthio-
1,2,4-triazole, with
(ii) an organic reducing agent consisting
essentially of 4-amino-2-methoxy-N,N,5-
trimethylaniline sulfate which is a
reducing agent for said silver salt in
(b)(i), and
(c) a coupler consisting essentially of 2',6'-
dihydroxytrifluoroacetanilide.
37. A heat developable photographic composition
comprising, in a polymeric binder:
(a) photosensitive silver halide,
(b) an image-forming combination comprising
(i) a complex of silver with a nitrogen
acid, with
(ii) an organic reducing agent for said com-
plex of silver with a nitrogen acid, and
(c) a resorcinol, dye-forming coupler that forms a
dye with the oxidized form of said reducing agent.
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38. A heat developable photographic composition
comprising, in a polymeric binder:
(a) a photosensitive silver halide gelatino
emulsion,
(b) an image-forming combination comprising
(i) a complex of silver with imidazole,
with
(ii) an organic reducing agent for said
complex of silver with imidazole, and
(c) a resorcinol, dye-forming coupler that forms
a dye with the oxidized form of said reducing
agent.
39. A heat developable photographic composition
for providing a dye enhanced silver image comprising, in a
polymeric binder:
(a) photosensitive silver halide gelatino
emulsion,
(b) an image-forming combination comprising
(i) a complex of silver with dodecyltetra-
zole, with
(ii) an organic reducing agent consisting
essentially of 2-methyl-4-(N-ethyl-
N-hydroxyethyl)-aminoaniline hydrogen
sulfate which is a reducing agent for
said complex of silver in (b)(i),
(c) a coupler consisting essentially of 2',6'-
dihydroxytrifluoroacetanilide, and
(d) a melt-forming compound.
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40. A heat developable photographic composition
for providing a dye enhanced silver image comprising, in a
polymeric binder:
(a) photosensitive silver halide,
(b) an image-forming combination comprising
(i) a silver salt of a heterocyclic
thione represented by the formula:
<IMG>
wherein Z' is alkylene containing 1 to 10
carbon atoms; R represents the atoms
necessary to complete a heterocyclic
nucleus selected from carbon, oxygen,
sulfur and nitrogen atoms, with
(ii) an organic reducing agent for said
silver salt of a heterocyclic thione,
and
(c) a resorcinol, dye-forming coupler that forms
a dye with the oxidized form of said reducing
agent.
41. A heat developable photographic composition
for providing a dye enhanced silver image comprising, in a
polymeric binder:
(a) photosensitive silver halide,
(b) an image-forming combination comprising
(i) a silver salt of 3-carboxymethyl-4
methyl-4-thiazoline-2-thione, with
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(ii) an organic reducing agent consisting
essentially of 4-amino-2-methoxy-N,N,5-
trimethylaniline sulfate which is a
reducing agent for said silver salt in
(b)(i), and
(c) a coupler consisting essentially of 2',6'-
dihydroxytrifluoroacetanilide.
42. In a thermographic element comprising a support
having thereon, in reactive association, in a polymeric
binder:
(a) an oxidation-reduction image-forming combina-
tion comprising
(i) an organic silver salt oxidizing agent,
with
(ii) an organic reducing agent for said
organic silver salt oxidizing agent,
the improvement comprising
(b) a resorcinol, dye-forming coupler that forms
a dye with the oxidized form of said reducing
agent.
43. A thermographic element as in Claim 42 wherein
said coupler consists essentially of a compound represented
<IMG>
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wherein R5 is haloalkyl containing 1 to 3 carbon atoms,
CH2OCH3, CH2SR7, NHR8, C2H4COOH, CH=CH2, NHC2H4Cl, alkyl
containing 1 to 10 carbon atoms or phenyl; R7 is alkyl
containing 1 to 5 carbon atoms or phenyl; and, R8 is hydrogen,
haloalkyl containing 1 to 3 carbon atoms, CH2OCH3 or C2H4COOH.
44. A thermographic element comprising a support
having thereon, in reactive association, in a polymeric
binder:
(a) an oxidation-reduction image-forming combina-
tion comprising
(i) a silver salt of 3-amino-5-benzylthio-
1,2,4-tetrazole, with
(ii) an organic reducing agent consisting
essentially of 4-amino-2-methoxy-N,N,5-
trimethylaniline sulfate which is a
reducing agent for said silver salt in
(b)(i), and
(b) a coupler consisting essentially of 2',6'-
dihydroxytrifluoroacetanilide.
45. A thermographic element comprising a support
having thereon, in reactive association, in a polymeric
binder:
(a) an oxidation-reduction image-forming combina-
tion comprising
(i) a complex of silver with imidazole,
with
(ii) an organic reducing agent for said com-
plex of silver with imidazole, and
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(b) a resorcinol, dye-forming coupler that forms
a dye with the oxidized form of said reducing
agent.
46. In a thermographic composition comprising
(a) an oxidation-reduction image-forming combina-
tion comprising
(i) an organic silver salt oxidizing agent,
with
(ii) an organic reducing agent for said
organic silver salt oxidizing agent,
and
(b) a polymeric binder,
the improvement wherein said composition comprises
(c) a resorcinol, dye-forming coupler that forms
a dye with the oxidized form of said reducing
agent.
47. A thermographic composition as in Claim 46
wherein said coupler consists essentially of a compound
represented by the formula:
<IMG>
wherein R5 is haloalkyl containing 1 to 3 carbon atoms,
CH2OCH3, CH2SR7, NHR8, C2H4COOH, CH=CH2, NHC2H4Cl, alkyl
containing 1 to 10 carbon atoms or phenyl; R7 is alkyl
containing 1 to 5 carbon atoms or phenyl; and, R8 is hydrogen,
haloalkyl containing 1 to 3 carbon atoms, CH2OCH3 or C2H4COOH.
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48. A thermographic composition comprising
(a) an oxidation-reduction image-forming combina-
tion comprising
(i) a silver salt of 3-amino-5-benzylthio-
1,2,4-triazole, with
(ii) an organic reducing agent consisting
essentially of 4-amino-2-methoxy-N,N,5-
trimethylaniline sulfate which is a
reducing agent for said silver salt in
(b)(i), and
(b) a coupler consisting essentially of 2',6'-
dihydroxytrifluoroacetanilide, and
(c) a polymeric binder.
49. A thermographic composition comprising
(a) an oxidation-reduction image-forming combina-
tion comprising
(i) a complex of silver with imidazole,
with
(ii) an organic reducing agent for said com-
plex of silver wlth imidazole,
(b) a resorcinol, dye-forming coupler that forms
a dye with the oxidized form of said reducing
agent, and
(c) a polymeric binder.
50. A process of developing a latent image in an
exposed photographic element as defined in Claim 1 comprising
heating said element to a temperature within the range of
about 100°C to about 250°C until a dye enhanced silver image
is developed.
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51. A process of developing a latent image in an
exposed photographic element as defined in Claim 15 comprising
heating said element to a temperature within the range of
about 100°C to about 250°C until a dye enhanced silver image
is developed.
52. A process of developing a latent image in an
exposed photographic element as defined in Claim 17 comprising
heating said element to a temperature within the range of
about 100°C to about 250°C until a dye enhanced silver image
is developed.
53. A process of developing a latent image in an
exposed photographic element as defined in Claim 21 comprising
heating said element to a temperature within the range of
about 100°C to about 250°C until a dye enhanced silver image
is developed.
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Description

Background Or the Invention
_ eld of the Invention
This inventlon relates to heat developable photographic
materials and processes for providing a dye enhanced silver
image. In one cr its aspects it relates to a heat
developable photographic element for producing a dye enhanced
silver image comprising a support having thereon, in reactive
association, a combination of photosensitive silver halide
with a certain image-forming combination and a certain resorcinol,
dye-forming coupler. In another of its aspects it relates to
a process for providing such a dye enhanced silver image by
merely heating the described heat developable photographic
material after imagewise exposure. A further aspect of the
invention relates to a thermographic material comprising the
described image-forming combination with the resorcinol,
dye-forming coupler.
Description of the State of the Art
It is well known to provide a silver image in a
heat developable photographic materlal. Heat developable
photographic materials are also known as photothermographic
materials. Heat developable photographic materials after
imagewise exposure are heated to moderately elevated temperatures
to provide a developed image in the absence of separate
processing solutions or baths. The heat development can provide a
developed silver image in the material.
The most common organic silver salts in heat
developable photographic materials are silver salts of
long-chain fatty acids, such as silver behenate, which generally
require hydrophobic binders. These organic silver salts are

useful with photosensitive silver halide in heat developable
photographic materials. These heat developable photographic
materials have encountered certain problems.
First, it is desirable to replace the silver salts
long-chain fatty acids to enable more effective use of
aqueous or hydrophilic compositions, such as aqueous silver
halide emulsions. Use of silver behenate as a source of
silver in heat developable photographic materials is not
particularly compatible with aqueous formulations of photo-
graphic silver halide.
Other organic silver salts have been proposed forheat developable photographic materials. These include, for
example, silver salts of benzotriazole, silver salts of
saccharin and related organic silver salts. These are
described, for example, in heat developable photographic
materials in ~.S. Patent 3,617,289 of Ohkubo et al, issued
October 2, 1971. While many organic silver salts can provide
an image in heat developable photographic silver halide,
a problem is involved with them. These materials use
undesirably high concentrations of total silver because any
image formed results from silver compounds, No suitable
answer to help solve this problem is apparent from the heat
developable photographic silver art.
It is desirable in many cases to enable exposure
of heat developable photographic materials to other than
the blue region of the visible spectrum. Difficulty is
often encountered in spectrally sensitizing photosensitive
silver halide to enable exposure to a broader range of the
visible spectrum in heat developable materials. It has been
3 desirable to produce a heat developable silver halide photo-
graphic material that enables use of aqueous photographic
-- 3 --

silver halide technology, permitting use o~ a broader range of
spectral sensitizing dyes while enabling the production of a
dye enhanced silver image.
Heavy metal salts of certain heterocyclic compounds,
such as heterocyclic azoles, are known in thermographic
materials in which the visible image is formed by imagewise
heating, not by a photographic process. The described
thermographic materials are not photographic materials and
do not involve problems encountered in dye enhancement of
silver images.
Certain heat developable photographic materials
are also known for producing a developed image in color as
described, for example, in U.S. Patent 3,531,286 of Renfrew,
issued September 29, 1970 and U.S. Patent 3,761,270 of
deMauriac and Landholm, issued September 25, 1973. In
these color-~orming materials a color-forming coupler is
required to produce the color image. However, the heat
developable materials are not designed to produce a dye
enhanced silver irnage with a resorcinol coupler, partlcularly
an image that has a neutral (black) or nearly neutral appearing
color.
Thermographic materials are also known for producing
an image in color. The image is produced by imagewise
heating such materials. These materials are not useful for
photographic processes requiring the photographic speed of
photosensitive silver halide in which a latent image is
produced by imagewise exposure to light. In addition,
colored film materials are known which can be made clear or
colorless in image areas when heated thermographically.

Such thermographic materials lack the desired photosensitivity
of heat developable photographic materials. None of these
materials involve the enhancement of a silver image with a
~ dye.
It has been proposed in certain photographic
materials to use the oxidized form of certain compounds to
react with other components of the material to change the
color of the resulting image. For example, in a diffusion
transfer photographic material, oxidized developer can be
diffused to a contiguous layer. This, however, does not
relate to heat developable photographic materials.
In photographic materials processed in processing
solutions or baths, it has been known to produce a dye image
which reinforces a silver image formed upon development.
This concept, however, has not been used in heat developable
photographic materials which involve different problems due
to the use of incorporated processing chemicals.
A heat developable photographic material which involves
a dye enhanced silver image is described in Research Disclosure,
Vol. 156, April 1977s Item 15676 of Willis. This heat
developable material, however, does not involve a coupler which
can form an image with oxidized developer. The heat
developable photographic material in this publication
involves providing a dye enhanced silver image by means of an element
comprising (A) at least one heat developable photographic layer
comprising (i) photosensitive silver halide, (ii) at least one
active silver halide developing agent, (iii) an activating
conccntration of a development activator precursor, and (iv) a
polymeric binder and (B) at least one layer comprising an

azoaniline dye that is bleached in the non-image areas of the
described element upon development of a latent image in the
layer (A) by uniformly heating. This involves a dye present
at the time of imagewise exposure and does not involve a
coupling mechanism.
There has been a continuing need to provide reduced
concentrations of silver in heat developable silver halide
photographic materials. There has also been a continuing
need for such improved materials which have increased
photosensitivity and enable more effective use of gelatino
silver halide emulsion technology.
Summary of the Invention
It has been found according to the invention that the
described advantages are provided in a heat developable photo-
graphic material for producing a dye enhanced silver image
comprising, in reactive association, (a) photosensitive silver
halide, with (b) an image-forming combination comprising (i) an
organic silver salt oxidizlng agent, with (ii) an organlc
reducing agent, and (c) a polymeric binder, by (d) a resorcinol,
dye-forming coupler that forms a dye with the oxidized form
of the described reducing agent. After imagewise exposure,
a dye enhanced silver image can be produced in the described
photographic material by heating the material to a temperature
within the range of about 100C to about 250C, such as
about 135C to about 170C. ~referably, for many uses, the
developed, dye enhanced silver image is neutral (black) or
nearly neutral appearing.
-- 6 --

The heat developable materials according to the
invention can contain a wide range of grain size of photosensitive
silver halide from very fine to coarse grain size. ~hen
large-grain photosensitive silver halide is used in a heat
developable material according to the invention, the dye
enhancement produces relatively high photographic speeds by
compensating for the low covering power of the silver obtained
from the large-grain photosensitive silver halide. When fine-grain
silver halide is used, lower concentrations of the fine-grain
photosensitive silver halide can be used without significantly
adversely affecting the desired image.
It has also been found that a thermographic material
can provide a dye enhanced silver image by imagewise heating
a material containing components (b), (c) and (d) in the
absence of the photosensitive silver halide.
Detailed Description of the Invention
. . . _
The term "material" as used herein, such as in
photographic material and thermographic materlal, is intended
to include elements and compositions. For lnstance, the
use of "photographic material" is intended to refer to
photographic element and photographic composition.
One embodiment of the invention, as described, is a
heat developable, photographic element for producing a dye
enhanced silver image comprising a support having thereon,
in reactive association, described components (a), (b), (c)
and (d). Another embodiment is a thermographic element for
producing a dye enhanced silver image comprising a support having
thereon, in reactive association, the described components (b),
(c) and (d).
The heat developable photographic materials according
to the invention comprise a photosensitive component which is
photosensitive silver halide. The photosensitive silver
halide is especially useful due to its high degree of

photosensitivity compared to other photosensitive components.
A typical concentration of photosensitive silver halide in a
heat developable photographic material according to the
invention is within the range of about 0.01 to about 1.0 mole
of photosensitive silver halide per mole of the described
organic silver salt oxidizing agent in the heat developable
photographic material. For example, a typical concentration
of photosensitive silver halide in the heat developable
photographic material is within the range of about 0.05 to
about 0.35 mole of photosensitive silver halide per mole of
silver salt of 1,2,4-mercaptotriazole derivative as described
herein. Other photosensitive materials can be used in com-
bination with the described photosensitive silver halide,
if desired. Preferred photosensitive silver halides are
silver chloride, silver bromide, silver bromoiodide, silver
chlorobromoiodide or mixtures thereof. A wide range of grain
size of photosensitive silver halide from very coarse-grain
to very fine-grain silver halide is useful. Selection o~ an
optimum reducing agent and optimum resorcinol coupler will be
influenced by the silver halide grain size and other properties
of the particular silver halide grains.
The photosensitive silver halide can be prepared
by any of the procedures known in the photographic art,
especially those procedures which involve the preparation of
photographic silver halide gelatino emulsions. Useful
procedures and forms of photosensitive silver halide for
purposes of the invention are described, for example, in the
Product Licensing Index, Volume 92, December 1971, Publication
9232 on page 107, published by Industrial Opportunities
3 Ltd., Homewell, Havant Hampshire, P09 lEF, UK. The photographic
silver halide, as described, can be washed or unwashed, can
-- 8 --

be chemically sensitized using chemical sensl~ization procedures
and materials known in the art, can be protected against the
production Or fog and stabilized against loss of sensitivity
during keeping as described in the described Product Licensing Index
publication.
A variety of organic silver salt oxidizing agents
can be useful in the described photographic and thermograph~C
materials. Especially useful organic silver salt oxidizing
agents are silver salts of 1,2,4-mercaptotriazole derivatives
represented by the formula:
H
Z _~N~jLS-(CH2 )nY
wherein Y is aryl containing 6 to 12 carbon atoms, such as
phenyl, naphthyl, and para-chlorophenyl; n is 0 to 2; and
Z is hydrogen, hydroxyl or amine (-NH2). Especially useful
organic silver salt oxidizing agents are those silver salts
of the described 1,2,4-mercaptotrlazole derivatives wherein Y
is phenyl, naphthyl, or para-chlorophenyl and Z ls amine (-NH2)
in the above formula (I). Such organic silver salt oxidizing
agents are described, for example, in Research Disclosure,
Vol. 158, June 1977, Item No. 15869 of Knight, deMauriac and
Graham.
Another useful class Or organic silver salt oxidizlng
agents is represented by the complexes of silver with a nitrogen
acid, such as a nitrogen acid selected from the group consisting
A
.~ . . .. . .... . .. . . . .. . . . . .

o~ imidazole, p~razole, urazole, 1,2,4-triazole and lH-
tetrazole nitrogen acids or combinations thereof. These
silver salts of nitrogen acids are described in, for example,
Research Disclosure, Vol. 150, October 1976, Item No. 15026
of deMauriac. Examples of ~seful silver salts of nitrogen
acids are the silver salts of the following compounds: lH-
tetrazole; ~-àodecyltetrazole; 5-n-butyl-lH-tetrazole; 1,2,~-
triazole; urazole; pyrazole; imidazole; and benzimidazole.
The 3-amino derivative of 1,2,4-triazole does not provide useful
results because the dye rormed is a ru~itive dye, that is the
dye bleaches upon heating and does not provide the dye
enhancement desired.
A furthe- class of useful organic silver salt
oxidizing agents include silver salts Or certain heterocycllc
thione compounds. Useful silver salts Or the described
heterocyclic thione compounds include those represented
by the formula:
`N - C=S
(Z')COOH
wherein Z' is alkylene containing 1 to 10 carbon atoms,
such as methylene, ethylene and propylene, R represents the
atoms necessary to complete a heterocyclic nucleus selected
rrom carbon, oxygen, sulfur and nitrogen atoms, such as a
thiazoline or imidazoline nucleus. Useful silver salts Or
-- 10 --
~'~
., . , :

71;JI.fi~
the described thione compounds include, for example, the
silver salts of the following compounds:
3-(2-carboxyethyl)-4-methyl-4-thiazoline-2-thione,
3-(2-carboxyethyl)benzothiazoline-2-thione;
3-(2-carboxyethyl)-5-phenyl-1,3,4-oxadiazoline-2-
thione;
3-(2-carboxyethyl)-5-phenyl-1,3,4-thiadiazoline-
2-thione,
3-carboxymethyl-4-methyl-4-thiazoline-2-thione,
3-(2-carboxyethyl)-1-phenyl-1,3,4-triazoline-2-thione,
1,3-bis(2-carboxyethyl)imidazoline-2-thione;
1,3-bis(2-carboxyethyl)benzimidazoline-2-thione,
3-(2-carboxyethyl)-1-methylimidazoline-2-thione,
3-(2-carboxyethyl)benzoxazoline-2-thione; and
3-(1-carboxyethyl)-4-methyl-4-thiazoline-2-thione.
Selection of an optimum organic silver salt
oxidizing agent or silver salt oxidizing agent combination
will depend upon such factors as the desired image, particular
silver halide, particular resorcinol, dye-forming coupler,
processing conditions and the like.
Preparation of the described organic silver salt
oxidizing agent is typically not carried out in situ, that is not
in combination with other components of the heat developable
photographic materials described. Rather, the preparation of
the oxidizing agent is typically carried out ex situ, that is
separate from other components of the heat developable
photographic materials. In most instances, the preparation of
the silver salt oxidizing agent, as described, will be separate
from the other components based on the ease of control of
preparation and storage capability.
The terms "salt" and "complex" as used herein are
-- 11 --

intended to include any type of bonding or complexing
mechanism which enables the resulting material to provide
desired imaging properties in the described heat developable
photographic materials and thermographic materials. In some
instances the exact bonding of the described silver salt
with the organic compound is not fully understood. Accordingly,
the terms "salt" and "complex" are lntended to include various
complexes and other forms of bonding which enable the desired
image-forming combination to provide the desired image.
The terms "salt" and "complex" are intended to include neutral
complexes and non-neutral complexes.
The described heat developable materials and
thermographic materials can contain a variety of organic
reducing agents. The organic reducing agent is typically
an organic silver halide developing agent. Combinations of
organic reducing agents, particularly combinations of organic
silver halide developing agents, can be especially useful.
It is important that the organic reducing agent provide an
oxidized form which ct~n react at processing temperature with
the resorcinol dye-forming coupler to provide a dye~ preferably
a neutral or nearly neutral appearing dye. Especially
useful reducing agents are primary aromatic amines including,
for instance, para-phenylenediamines. Examples of useful
primary aromatic amines include 4-amino-N,N-dimethylaniline;
4-amino-N,N-diethylaniline; 4-amino-3-methyl-N,N-diethylaniline
(also known as N,N-diethyl-3-methyl-para-phenylenediamine;
4-amino-N-ethyl-N-~-hydroxyethylaniline; 4-amino-3-methyl-
N-ethyl-N-~-hydroxyethylaniline; 4-amino-3-methoxy-N-ethyl-
N-~-hydroxyethylaniline; 4-amino-N-butyl-N-gamma-sulfobutylaniline;

4-amino-3-methyl-N-ethyl-N-B-sulfoethylaniline; 4-amino-3-~-
(methanesulfonamido)ethyl-N,N-diethylaniline; 4-amino-3-
methyl-N-ethyl-N-~-(methanesulfonamido)ethylaniline, 4-
amino-3-methyl-N-ethyl-N-~-methoxyethylaniline and the like. Salt
forms of the described reducing agents can be useful; however, in
many cases the haloacid salts are preferably avoided to reduce
undesired formation of silver halide. Selection of an optimum
reducing agent or combination of reducing agents will depend
upon such factors as the desired image, the particular
photosensitive silver halide, the particular resorcinol,
dye-forming coupler, the particular organic silver salt
oxidizing agent, processing conditions and the like.
The term "silver halide developing agent" herein
is intended to include compounds which are developing agents
and developing agent precursors in the described heat developable
photographic materials and thermographic materials. That
is, those compounds are intended to be included which are
not developing agents in the heat developable photographic
material until a condition occurs such as heating of the
photographic material.
An especlally useful reducing agent is one that
consists essentially of a para-phenylenediamine silver
halide developing agent that exhibits an E 1/2 value in aqueous
solution at pH 10 within the range of -25 to ~175 millivolts
versus SCE. The term "E 1/2 value" herein means half wave
potential. The term "SCE" herein means saturated calomel electrode.
These values are determined using analytical procedures
known in the photograpnic art and described, for instance,
in the text "The Theory of the Photographic Process," 4th
Edition, Mees and James, 1977.
- 13 -

A useful concentration of the described reducing
agent in a heat developable photographic material according
to the invention is typically within the range of about 0.25
mole to about 2.0 moles of the reducing agent per mole of the
described silver salt oxidizing agent. An especially useful
concentration of reducing agent is within the range of about
0.25 to about 1.0 moles of reducing agent per mole of the
described silver salt oxidizing agent. The optimum concentration
of reducing agent can be determined based upon such factors
as the desired image, the particular organic silver salt
oxidizing agent, processing conditions, other components of the
heat developable photographic material and the like.
A variety of resorcinol, dye-forming couplers is useful
in the heat developable photographic materials and thermographic
materials of the invention. The resorcinol, dye-forming
coupler is preferably one that forms a neutral (black) or nearly
neutral appearing dye with the oxidized form of the described
reducing agent. The mono-substituted resorcinol couplers wlth a
substituent in the two position are particularly useful as
described. The resorcinol, dye-forming coupler and other
components in the materials of the invention should be stable
to a sufficient degree that avoids any significant, adverse
interaction in the photographic material and thermographic
material prior to producing a desired image at processing
temperatures. For instance, optimum results are obtained when
the resorcinol, dye-forming coupler does not adversely interact
with other components ln the photographic material and thermo-
graphic material until the oxidized form of the described
reducing agent is produced at processing temperature, as
described. It is also necessary that the resorcinol
dye-forming coupler be in a location with respect to the
- 14 -

oxidized form of the described reducing agent upon processing
to enable the formation of the desired dye to enhance the
silver image formed upon heating of the photographic material.
Certain resorcinol couplers which are useful according
to the invention can be represented by the structural formula:
COUP - LINK - Y'
wherein COUP is a 2,6-dihydroxyphenyl moiety, a 2,4-dihydroxy-
phenyl moiety or a 3,5-dihydroxyphenyl moiety, LINK is a
divalent linking group which serves to join the COUP moiety
- 14a -

to the Y' moiety and Y' ls a moiety of such size and
configuration that does not adversely affect the desired
coupling or the desired sensitometric properties in the
described heat developable photographic materials of the
invention. The COUP moiety is preferably unsubstituted in
its remaining ring positions, although it can contain
substituents in one or more of the remaining positions on the
benzene ring as long as the substituents do not adversely
affect the desired coupling or other desired properties
of the photographic or thermographic material of the invention.
Typical of such optional substituents are lower alkyl
groups containing 1 to 4 carbon atoms, such as methyl,
ethyl, propyl and butyl, and halogen substituents, such as
chloro and bromo. The LINK group can be any divalent group
which serves to connect the COUP moiety with the Y' moiety.
The particular structure of the coupler will affect the hue
of the resulting dye image. Especially useful LINK groups
include the following: -NHC0-, -CONH, -NHCONH-, -NHS02-,
and -NH-. Numerous moieties are known for use in connection
with couplers intended for incorporation in photographic
elements and can be employed as Y' in the described
resorcinol couplers according to the invention. Selection
of an optimum COUP, LINK and Y' moiety will depend upon such
factors as the particular components in the heat developable
photographic material, desired image, processing conditions
and the like.
A useful embodiment of the invention is one
wherein the described coupler is a resorcinol compound
represented by the formula:
- 15 -

~i$ :1-;
HO ~ OH
R ~ R2
- wherein O O O
Rl is hydrogen, COH, NHCR5, CR6, or NHSo2R7;
O O O
R2 is hydrogen, COH, CNHCH2CH20H, or CNH~C6H5~0C5Hlln;
O O
R3 is hydrogen, NHCR5, or CR6;
O O
R is hydrogen, COH, CNHCH2CH20H or
o
CNH~C6H5~0C5Hlln;
R5 is haloalkyl containing 1 to 3 carbon atoms, such as
CC13 CF3, and C3H4Br3, CH20CH3, CH2SR ,
C2H4COOH, CH=CH2, NHC2H4Cl, alkyl containing 1 to 20
carbon atoms, such as 1 to 10 carbon atoms, including
methyl, ethyl, propyl, and decyl, or phenyl;
R6 is OH, NH2, NHCH2CH20H, or NH~C6H5~0C5Hlln;
R7 is alkyl containing 1 to 5 carbon atoms, such as
methyl, ethyl, propyl or pentyl, or phenyl; and
R8 is hydrogen, haloalkyl containing 1 to 3 carbon atoms,
such as CC13, CF3 and C3H4Br3, CH20CH3~ or
C2H4COOH .
Alkyl and phenyl, as described, are intended to include alkyl
and phenyl that are unsubstituted alkyl and phenyl as
well as alkyl and phenyl that contain substituent groups
that do not adversely effect the desired image. An example
of a suitable substituent group is alkyl containing 1 to 3
carbon atoms, such as methyl or ethyl.
- 16 -

Representative use~ul resorcinol couplers
include the following compounds:
/OH
- RC-l ./ \
NH
OH
~01
RC-2 ~ NHCO-~
OH
OH
RC-3 ~ H !~
/OH
RC-4 ~ -NHCO--~ /o
OH C~
/OH
RC-5 ~ -NHCO--\ ~--CI
OH
- /OH
RC-6 ~ ~--NHCO~
OH Br
/OH
RC-7 ~ -NHCO-~
\OH
/OH
10 RC-8 ~ ~--NHCO-~ -C-N
OH
/OH
RC-9 ~ -NHCO-~ -NH2
OH
- 17 -

~OH ~NH
RC-10 ~ NHCO-~
OH NH
~0
R C - l l ~-NHCO~
OH N~
~OH
RC-12 ~NHCO--~ ~t-NO
OH
~OH
RC -13 ~-NHCO-~
OH \N2
~OH
RC- 14 ~ -NHCO-~
OH \CF3
~OH ~CH
RC-15 ~ -NHCO ~-
o = ~
OH CH3
~OH
R C -1 6 ~ -NHCO-~
OH CH3
HO~
RC-17 ~-NHCO--~ ~4-C H -t
H~
~OH
RC-18 ~ ~--NHCO--~ ~--C H~-t
\OH
-- 18 -

*~
OH
RC-l9HO--~ /7-NHCO--~ ~--C H~-t
/OH
RC-20 ~ -NHC-O-~ -C5H~l-n
\OH
/OH
RC-21 ~ C 6 13
RC-22~ ~ -NHCO--\ /--c7Hl 5 n
/OH
RC-23HO \ _ /- NHCO--\ /~-C8H -n
/OH
RC-24~ _ ~ NHCO--\ /~-CeH~7-n (C-3)
OH
HQ
RC-25~ _ ~ NHCO ~\ /'-C8H -n
RC-26 \ _ ~ - NHCO-~ -CeH -n
H C\ /OH
RC-27~ _ ~ NHCO--\ /~-C H -n
/OH
10- RC-28~ _ ~ NHCO ~ -Cl~H -n
- OH
-- 19 --

s~
H~
RC-30 ~\ /b-NHCO~
H6 ~Hs
/OH
RC-31 ~ -NHCO~ 5
OH ~Hs
/OH
RC-32 ~ ~-NHCO~
OH O~H OCH
3 3
/OH
RC-33 ~ - NHCO--~ /-
OH 0~ H -n
6 1 1
H~
RC-34 \ _ /~ NHCO--\ /--OC H -n
H~
/OH
RC-35 \ _ / N CO \ _ / OCsHl1 n
/OH
\ _ /--NHcO~ -OC H -n
/OH
RC-37 \ _ / NHC0 ~ -OCloH -n
OH
. .- 20 -

/OH
RC-38 ~ NHCO~
OH OC H -n
1 o zl
OH
RC-39 _ / 9 \ /--OC H -n
/OH
RC-40 ~ ~-- NHCO~ -OC H -n
1 2 Z 5
OH
H4
RC-41 \ _ / NHCO-~\ /o-oc H -n
H~
H~ .
RC-42 ~ -NHCO-~
H~ O~ H -n
/OH
RC-43 ~ /'-NHCO-'~ ~'
\OH O~ H -n
1 ~3 37
/OH
RC-44 ~ ~t-NHCO-~ -SCH3
OH
/OH
RC-45 ~ NHCO--~ ~-
OH lo 2 ~ n
/OH H~
RC-46 ~ ~-NHCO-~ -CONH-~
OH H~
. /OH
10- RC-47 ~ NHCO-~ -NHCOCH=CH
- . OH
- 21 -

.. ,OH
RC-48 ~ NHCO~ NHCOCF
OH
/OH
RC-49 ~ - NHCO-~ -NHCO
OH .
/OH /OCOCHS
- RC-50 ~ -NHCO-~
OH OCOCHS
. ~OH
RC-51 ~ -NHCO-~
\OH SOzCI
/ Oi~
RC-52 ~ -NHCOCH=CH-~
OH
RC-53 - ~ 112 5 n ~C4 H -t
OH
~01
-
RC-55 ~ ~-NHCO-CHzCH~CH~C
OH
/OH
RC-56 ~-NHCO-C H -n
OH
/OH
RC-57 \ - /--NHco-cl7Hs~-n
OH
- 22 -

RC-58 ~ NHC0
OH
~C-59 ~ ~ -NHCO~
/OH
RC-60 ~ _ , CONH~ -OC H -n
OH
/OH
RC-61 ~ _ , , _ , 5 , 7 n
- RC-62 HN--~ ~--CH=CH-~ -NH
C=O
C~O
n
HO OH / ~
HO OH
, ~OH /CH
RC-63 ~ ~-NHCONH-~
OH C~3
0~ '
RC-64 ~ /--NHCONH-7~ ~--NH
- 23 -

~OH
RC-65 ~ NHSO C H -n
OH
~OH
Other resorcinol couplers are described in the following
examples.
- 24 -

A pre~erred resorcinol dye-rorming coupler ls
represented by the rormula:
NHCoR5
H ~ OH
wherein R5 is as described. Within this formula resorcinol,
dye-forming couplers areJ ~or instance, 2,6-dihydroxyacetanllide,
2',6'-dihydroxytri~luoroacetanilide, and a compound represented
by the formula:
O 1 3
HO C ~
Due to differences ln solubility and other properties,
it can be use~ul, in some cases to coat a coupler, as described,
in the rorm of a latex dispersion or other suitable form
than a solution in a suitable solvent. Those couplers that
are soluble in water can be userully coated rrom an aqueous
formulation.
Resorcinol couplers as descrlbed can be prepared
~rom amino resorcinols or dihydroxybenzoic acids. ~or some o~
the described resorcinol couplers, an appropriate amino
resorclnol can be condensed with an appropriate acid chloride
in the presence o~ a suitable base, such as pyridine, quinolin,
20 N,N-dimethylaniline and the like, as an acid acceptor to yield
the desired resorcinol coupler. Other resorclnol couplers,
as described, can be prepared by condensation Or an appropriate
dihydroxybenzylic acid with an appropriate amine in the
presence Or a phosphorous trifluoride catalyst and an amine
acid acceptor. These resorcinol couplers can be prepared by
~irst converting the dihydroxybenzoic acid to the acid chloride
(while blocking the hydroxyl groups to prevent the acid chloride
- 25 -
:
'~

from reacting with itself) and then condensing the resultant
acid chloride with an appropriate amine, followed by hydrolysis
to deblock the hydroxy groups. Still other of the described
resorcinol couplers can be prepared by converting an appropriate
dihydroxybenzoic acid to its methyl ester and then conducting
a transesterification reaction with an appropriate alcohol
in the presence of a base catalyst, such as tetraisopropylortho-
titanate. These same resorcinol couplers can be prepared by
reacting the potassium salt of an appropriate dihydroxybenzoic
acid with an appropriate bromide in the presence of a suitable
catalyst, such as a suitable ether catalyst.
The concentration of resorcinol coupler
incorporated in the photographic material is sufficient
for each mole of total silver in the material to provide
the desired dye. Less than the stoichiometric equivalent of
coupler can be useful, particularly if the dye densities
obtained with the photographic material are too high for the
use intended for the material. Alternatively, a concentr-ation
that is greater than the stoichiometric amount of coupler
can be useful, if desired. Typically, the photographic material
contains about 0.1 to about 1.0 mole cf the described resorcinol
coupler per mole of total silver in the photographic material.
A preferred concentration of the resorcinol coupler is within
the range of about 0.25 to about 0.75 mole of coupler per mole of
total silver in the photographic material. A heat developable
photographic material or thermographic material also typically
comprises about 0.1 to about 1.0 mole of the described coupler
per mole of the described organic silver salt oxidizing agent.
The tone of the combined silver and dye images produced
3 according to the invention will vary depending upon such factors
as the silver morphology of the developed silver image, the
- 26 -

covering power of the silver materials, the particular coupler,
the particular developing agent, processing conditions, and the
like. In heat developable materials that provide a brown
silver image, the dye produced must be complimentary in hue
in order to obtain a desired hue for the combined silver and
dye image.
The term "neutral" as employed herein is intended to
include hues which occasionally are referred to in the photographic
art as blue-black, gray, purple-black, black and the like.
Whether or not a given developed image is "neutral" can be
readily determined by visual inspection. A more precise
procedure for determining whether or not an image is "neutral"
would be to formulate a photographic element according to the
invention and then expose and develop it as described to provide
a developed maximum density of between 0.3 and 2Ø This
developed density would then be employed to generate a
spectral photometric curve of wavelength versus diffuse
reflection density or diffuse transmition density (depending
on whether the support is opaque or transparent), uslng
commonly available equipment used in the photographic art.
If the spectral photometric plot of density versus wavelength
does not contain any 10 nanometer interval in the range of
420 to 650 nm which departs by more than 10% from the mean
density over that range, then the image obtained would be
considered to have a "neutral" hue for purposes of the
invention.
It has been found that in some photographic materials,
according to the invention, increased dye density can be
provided by addition of a polymeric latex to the photographic
material. Other advantageous affects can be provided by the
addition of a latex with the described reducing agent. These
- 27 -

advantages obtained when a latex is used with an incorporated
silver halide developing agent are described, for example, in
Research Disclosure, August 1976, Item No. 1~850, pages 77-99,
published by Industrial Opportunities Ltd., Homewell,
Havant Hampshire, PO9 lEF, UK. Accordingly, in some instances
it is desirable to incorporate a latex into the photographic
compositions in preparation of the photographic elements
according to the invention. The latex is typically added to
either or both of the resorcinol coupler and the described
reducing agent prior to their being mixed and incorporated
into the composition for coating on the described support.
The heat developable photographic elements and
thermographic elements according to the invention can comprise
a variety of supports which can tolerate the processing
temperatures employed according to the invention. Typical
supports include cellulose ester film, poly(vinyl acetal) film,
poly(ethylene terephthalate) film, polycarbonate film and
polyester film supports. Related film and resinous support
materials, as well as paper, glass, metal and the llke supports
which can withstand the processing temperatures descrlbed are
also useful. Typically, a flexible support is most useful.
The heat developable photographic compositions and the
thermographic compositlons according to the invention can be
coated on a suitable support by various coating procedures
known in the photographic art including dip coating, airknife
coatlng, curtain coating or extrusion coating using hoppers.
If desired, two or more layers can be coated simultaneously.
It is often advantageous to include a heat sensitive
base-release agent or base precursor in the heat developable
3 photographic materials and thermographic materials according
to the invention to provide improved and more effective image
development. A base-release agent or base precursor, as
- 28 -

. ~..~11
employed herein, is intended to include compounds which upon
heating in the heat developable photographic material and
- thermographic material provide a more effective reaction between
the described photosensitive silver halide, and the image-forming
combination in addition to improved reaction between the
oxidized form of the reducing agent and the resorcinol
dye-forming coupler. Examples of useful heat sensitive
base-release agents or base precursors are aminimide base-release
agents as described in Research Disclosure, Vol. 157,
May 1977, Items 15733, 15732, 15776 and 15734; guanidinium
compounds, such as guanidinium trichloroacetate; and, other
compounds which are known to release a base moiety but do not
adversely affect photographic silver halide materials.
A range of concentration of the heat sensitive
base-release agent or base precursor is useful in the described
heat developable photographic materlals and thermographic
materials. The optimum concentration of heat sensitive
base-release agent or base precursor will depend upon such factors
as the desired image, particular coupler, particular reducing
agent, other components of the lmaging materlal, processlng
conditions and the like. A useful concentratlon Or described
base-release agent is typically within the range of about
~.25 to 2.5 mole of base-release agent or base precursor
per mole of silver ln the heat developable photographic material
and thermographic material according to the invention.
The heat developable photographic materials and
thermographic materials according to the invention can contain
an image toner if desired. The optimum toning agent will
depend upon such factors as the particular heat developable
3 photographic material, the desired image tone, particular
processing conditions, particular silver halide and the like.
- 29 -
- , ~,

In some cases, certain image-toning agents can provide better
results with certain organic silver salt oxidizing agents,
such as certain 1,2,4-mercaptotriazole derivatives, than with
other organic silver salts. A simple screening test can be
useful to select an optimum image-toning agent, if desired. One
such test comprises that described in following Example 1.
In this test the most useful toning agent is typically that
toning agent that provides the most "neutral" image. Some
toning agents are also found to have other desired effects
in the heat developable photographic material and thermographic
material. For instance, some toning agents provide added
development acceleration in the described heat developable
photographic materials. Combinations of toning agents can be
useful if desired. In most instances, an added toning agent
is not necessary to provide a desired "neutral" image tone
in a heat developable photographic material and thermographic
material according to the invention.
If a toning agent is used, a range of concentration
of toning agent can be employed. A typically useful concen-
tration of toning agent ls within the range of about 0.005 toabout 0.05 mole of toning agent per mole of silver in the heat
developable photographic material and thermographic material.
The optimum concentration of toning agent will depend upon
such factors as the particular photographic material, processing
conditions, desired image, the nature of the toning agent,
and the like.
A "melt-forming compound" can be useful in some of
the photographic materials and thermographic materials in order
to provide an improved developed image. A melt-forming
compound can be especially useful with photographic materials
containing silver salts of nitrogen acids. The term
"melt-forming compound" as employed herein, is intended to
- 30 -
.. ~,
... . .. . . . . . . .
.. .. . . . .

~ 6~
mean a compound which upon heating to the described processing
temperature provides an improved reaction medium, typically
a molten medium wherein the described image-forming combination
can provide a better image upon development. The exact
nature of the reaction medium at processing temperatures
described is not fully understood; however, it is believed
that at the reaction temperatures a melt occurs which permits
the reaction components to better interact. If desired, a
melt-forming compound can be included with other components
of the heat developable photographic material and thermographic
material.
The optimum concentration of the various components
of the photographic material and thermographic material,
according to the invention, will depend upon a variety of
factors as described An especially useful heat developable
photographic material according to the invention comprises,
for each mole of photosensitive silver halide, 3.0 to 20.0 moles
of the described organic silver salt oxidizing agent, and
1.0 to 5.0 mole of the described reducing agent with 1.0 to
5.oO mole of the resorcinol, dye-forming coupler.
The organic silver salt oxidlzing agent can contain
a range of ratios of (1) the organic moiety, such as the 1,2,4-
mercaptotriazole moiety, to (2) the silver ion. The optimum
ratio of the organic moiety to silver ion in the organic
silver salt oxidizing agent will depend upon the particular
organic moiety, such as the particular 1,2,4-mercaptotriazole
derivative, the particular heat developable photographic
material or thermographic material, processing conditions,
particular resorcinol coupler and the like. However,
3 the molar ratio of the organic moiety to silver as silver ion
ln the salt is usefully within the range of about 0.5:1.0 to about
3.0:1Ø An especially useful ratio of the described organic
- 31 -

moiety to silver as silver ion is wlthin the range of 1.0:1
to 2.0:1Ø
~ The heat developable photographic materials of the
invention can also contain a range of pAg. The pAg can be
measured using conventional calomel and silver-silver chloride
electrodes, connected to a commercial digital pH meter.
The typical pAg in a dispersion containing the described
imaging components according to the invention is within the
range of about 2.5 to about 7.5, with a preferred range of pAg
being 3.5 to 6.5. The optimum pAg will depend upon the described
factors, such as the particular heat developable photographic
material, desired image, processing conditions, and the like.
A dispersion containing the described components
according to the invention typically has a pH which is within
the range of about 1.5 to 7Ø An especially useful pH for
a dispersion, as described, is within the range of about 2.0
to 6.o with the preferred range being about 2.5 to 5Ø
Spectral sensitizing dyes can be useful in the
described materials of the invention to confer additional
sensitivity to the materials. Useful spectral sensitizing
dyes are described, for example, in the Product Licensing Index,
Volume 92, December 1971, Publication 9232, pages 107-110,
paragraph XV, published by Industrial Opportunities Ltd.,
Homewell, Havant Hampshire, PO9 lEF, UK. An advantage of
certain heat developable photographic materials according to the
invention, i.e. those that enable use of conventional silver
halide emulsions, especially silver halide gelatino emulsions,
is that a range of spectral sensitiæing dyes is useful in such
materials. In many heat developable photographic materials
the range of useful spectral sensitizing dyes is often
undesirably limited. This advantage of these certain heat
developable photographic materials of the invention is due
- 32 -

p~
in part to the fact that these heat developable photographicmaterials can use conventional silver halide emulsions,
especially silver halide gelatino emulsions. Selection of
- an optimum spectral sensitizing dye or dye combination
depends upon such factors as the particular silver halide
used, the desired spectral sensitivity, and the like. A
preferred heat developable photographic material, according
to the invention, contains a spectral sensitizing dye selected
from the group consisting of cyanines and merocyanines and
combinations of these dyes. Especially useful spectral
sensitizing dyes include thiocarbocyanine dyes, merocyanine
dyes containing a rhodanine moiety, solubilized oxacarbocyanine
dyes, oxacarbocyanine dyes, and merocyanine dyes containing
a 2-thio-2,4-oxazolidinedione moiety.
A range of concentration of spectral sensitizing dye
or dye combination is useful in the described heat developable
photographic materials. Typically, the spectral sensitizing
dye or dye combination concentration is within the range of
about 0.5 to about 2.0 grams of dye or dye combination per mole of
silver halide in the heat developable photographic material.
It is desirable in certain cases depending upon the
desired image to add a separate post-processing image stabilizer
or stabilizer precursor to the described heat developable photo-
graphic materials according to the lnvention. Such stabilizers
or stabilizer precursors include sulfur compounds which do not
adversely affect the desired sensitometric properties of the
heat developable photographic material, but which upon heating
of the photographic material form a stable mercaptide in the
non-image areas of the photographic material. In certain
cases photolytically activated polyhalogenated compounds can be
useful, but these compounds have been found in some cases to be
less desirable than other stabilizers or stabilizer precursors.
- 33 -

The heat developahle photographic materials accordingto the invention can contain other addenda such as development
modifiers that function as speed-increasing compounds, hardeners,
plasticizers and lubricants, coating aids, brighteners, absorbing
and filter dyes, matting agents, antihalation dyes and
antihalation layers, antistatic materials or layers, and the
like. These are described, for example, in the Product Licensing
Index, Volume q2, December 1971, Publication 9232, pages 107-110.
The described components of the photographic materials
and thermographic materials according to the invention can be
in any suitable location in the photographic material and
thermographic material which provides the desired image.
For example, if desired, one or more of the components of the
photographic element and thermographic element described can
be in one or more layers of the element. In some cases it can
be desirable to include certain percentages of the described
reducing agent, organic silver salt oxidizing agent, and/or
other addenda in a protective layer or overcoat layer over the
photographic layer of the element as described. The components,
however, must be in a location which enables their desired
interaction upon processing.
It is necessary that the photosensitive silver halide,
as described, and other components of the imaging combination
be in "reactive association" with each other in order to provide
the desired image. The term "in reactive association", as
employed herein, is intended to mean that the photosensitive
silver halide and the image-forming combination and described
coupler are in a location with respect to each other which
enables the desired processing and provides a useful dye
- 34 -

enhanced silver image. It is believed that the latent image
formed upon imagewise exposure of the photosensitive silver
halide acts as a catalyst for the image-forming combination
containing the organic silver salt oxidizing agent. In turn,
the oxidized form of the reducing agent resulting upon processing
reacts, it is believed, with the described resorcinol, dye-forming
coupler to provide the desired dye in the image areas of the
element.
If desired, other heat developable photographic
materials or thermographic materials can be useful in combination
with the photographic materials and thermographic materials
according to the invention. The other heat developable
photographic materials and thermographic materials must be
compatible with and not adversely affect the image formation
in a photographic material and thermographic material according
to the invention.
An especially useful embodiment of the invention
is a heat developabie photographic element for providing a
dye enhanced silver image comprising a support having thereon,
in reactive association, (a) a photographic silver hallde,
especially a photographic silver halide gelatino emulsion,
(b) an image-forming combination comprising (i) a silver salt
of 3-amino-5-benzylthio-1,2,4-triazole, with (ii) an
organic reducing agent consisting essentially of 4-amino-2-
methoxy-N,~,5-trimethylanilinesulfate, (c) a coupler
consisting essentially of 2',6'-dihydroxytrifluoroacetanilide,
and (d) a polymeric binder, such as a gelatino binder.
Another useful embodiment of the invention is
a heat developable photographic element for providing a dye

J~
enhanced silver image comprising a support having thereon, in
reactive association, (a) photosensitive silver halide,
(b) an image-forming combination comprising (i) a complex of
~ silver with 5-dodecyltetrazole, with (ii) an organic reducing
agent consisting essentially of 4-amino-3-methyl-N-ethyl-N-
~-hydroxyethylaniline hydrogen sulfate, (c) a coupler
consisting essentially of 2',6'-dihydroxytrifluoroacetanilide,
(d) a polymeric binder, especially a gelatino binder and
(e) a melt former, as described.
A further useful embodiment of the invention is a
heat developable photographic element for providing a dye
enhanced silver image, as described above, wherein the
complex of silver with dodecyltetrazole is replaced with a
silver salt of 3-carboxymethyl-4-methyl-4-thiazoline-2-
thione. This embodiment of the invention can have improved
post-processing image stability when the photosensitive silver
halide is silver iodide.
Another embodiment of the invention is a heat
developable photographic composition for providing a dye
enhanced silver image comprising (a) photosensltive silver
halide, (b) an image-forming combination comprising (i) an
organic silver salt oxidizing agent, as described with (ii) an
organic reducing agent, also as described, (c) a resorcinol,
dye-forming coupler that forms a neutral or nearly neutral
appearing dye with the oxidized form of the reducing agent
and (d) a polymeric binder.
The heat developable photographic materials of the
invention can be useful for thermographic imaging in the
absence of the described photosensitive silver halide.
Accordingly, another embodiment of the invention is a
thermographic element comprising a support having thereon,
in reactive association, (a) an oxidation-reduction image-forming
- 36 -

p~
combination comprising (i) an organic silver salt oxidizing agent,as described, with (ii) an organic reducing agent, also as
described, (b) a resorcinol, dye-forming coupler that forms a
neutral or nearly neutral appearing dye with the oxidized
form of the reducing agent, and (c) a binder. An especially
useful thermographic element comprises a support having
thereon, in reactive association, (a) an oxidation-reduction
image-forming combination comprising (i) a silver salt of 3-
amino-5-benzothio-1,2,4-triazole, with (ii) an organic
reducing agent consisting essentially of 4-amino-2-methoxy-
N,N,5-trimethylanilinesulfate, and (b) a coupler consisting
essentially of 2',6'-dihydroxytrifluoroacetanilide, and (c)
a polymeric binder, especially a gelatino binder.
A variety of imagewise exposure means are useful
with the heat developable photographic materials according
to the invention. The imaging materials according to the
invention are typically sensitive to the ultraviolet and blue
regions of the spectrum and exposure means which provide this
radiation are preferred. Typically, however, lf P spectral
sensitizing dye is employed ln the heat developable photographlc
materials, exposure means using other ranges of the spectrum
are applicable. Typically, a heat developable photographic
element according to the invention is exposed imagewise with a
visible light source, such as a tungsten lamp, although other
sources of radiation are useful. Such other sources of radiation
include, for instance, lasers, electron beams, X-ray sources
and the like. The heat developable photographic materials
are typically exposed imagewise to provide a developable
latent image.
- 37 -
::
. .:
,: :

A visible image can be developed in the photographic
material according to the invention within a short time,
such as within several seconds, merely by uniformly heating
the heat developable photographic material to moderately
elevated temperatures. For example, the exposed photographic
material can be heated to a temperature within the range
of about 100C to about 250C, such as a temperature within the
range of about 135C to 170C. Heating is carried out until
a desired image is developed, typically within about 1 to about
60 seconds, such as within about 1 to about 30 seconds.
At the lower processing temperatures, such as ternperatures
of about 125C, development of an image may require a
longer processing time. However, at the lower processing
temperatures, such as below about 140C, post-processing
stabilization may be somewhat less than desired in most
instances.
Another embodiment of the invention is a process
of developing a latent image in an exposed photographic
elemert according to the inventlon comprising heating the
element to a temperature withln the range of about 100C
to about 250C, such as a temperature within the range of
about 135C to about 170C, until a neutral or near neutral
appearing dye enhanced silver image is developed~
Although it is often undesirable, due to the lack
of control in preparation, the described photosensitive
silver halide can be prepared in situ in the described
material according to the invention. Such a method of
preparation of photosensitive silver halide in a photographic
material is described, for example, in U.S. Patent 3,457,075
of Morgan et al, issued July 22, 1969.
- 38 -

A variety of means can be employed to provide the
necessary heating of the described photograph~c material and
thermographic material to provide a developed image. The
heating means can be a simple hot plate, iron, roller, infrared
. .
heating means, or the like.
Processing according to the invention is typically
carried out under ambient conditions of pressure and humidity.
Pressures and humidity outside normal atmospheric conditions
can be employed if desired; however, normal atmospheric
conditions are pre~erred.
The following examples are included for a further
understanding of the invention.
Example 1
This illustrates the invention.
A dispersion of a silver salt of 3-amino-5-benzylthio-
1,2,4-triazole (referred to herein as ABT) was prepared
having a silver salt dispersion weight of 5.753 kilograms
per silver mole, approximately 1% gelatin at a ligand to silver
ion molar ratio of 1.5 with pH adjusted to 2.5 with nitric
acid. The resulting dispersion was mixed with other
components to provide a heat developable photographic
material as follows:
ABT silver salt dispersion 86.9 g
(as above)
2',6'-dihydroxytrifluoro- 14.4 g
acetanilide (resorcinol
coupler) (C-l)
(30~ by weight in water)
distilled water 21.6 g
surfactant (Surfactant lOG 0.7 g
which is a trade name and a
polyglycidol ether available
from the Olin Corporation, U.S.A.)
(10% by weight in water)
- 39 -

3~
3-methyl-5-mercapto-1,2,4- 2.25 g
triazole (2.2~ by weight
in ethanol) (antifoggant)
gelatin (binder) (20~ by weight12.9 g
in water, pH adjusted to 2.5
with nitric acid)
4-amino-2-methoxy-N,N~5~tri- 11.3 g
methylanilinesulfate (reducing
agent) (14.2% by weight in water) (D-l)
silver bromoiodide (2.5% iodide, 2.16 g
0.24 ~m cubic grain, 0.754
kilograms per silver mole)
The resulting composition was coated at 9.0 grams
per square foot (equivalent to 96.9 grams per square meter)
on a gelatin subcoated poly(ethylene terephthalate) film support.
The resulting heat developable photographic element was
imagewise exposed to light to provide a developable latent
image. The image was developed by heating the element to
a temperature of 155C for 30 seconds. A dye enhanced silver
image was produced having a maximum visual diffuse density of
1.63 and a minimum density of 0.20.
Examples 2-14 - Reducing Agents
The procedure described in Example 1 was repeated
with the exception that the reducing agents listed in
following Table I were used in place of the described
analinesulfate reducing agent of Example 1. The processing
conditions including time and temperature range and the
particular reducing agent are listed in Table I. In each
instance a dye enhanced silver image was produced.
- 40 -

Table I
Proc e s s
Example time/temp .
No. ~ (sec./C~
2 N (CH3) 230"/135-165
~- NDS
COOH
NH2
(D-24)
3 H5c2-N-c2H4oH 30"/125-145
2PTS
NH2
(D-26)
4 ~2Hs)2 30"/125-135
10~ , .
3 ~ S03K
NH 2
t~-28,
N (CH3) 230"/145-185
CI~Cl
NH2
(D-7)
6 N (C2H5) 25 /135-155
2PTS
NH2
(D-3)
7 N(CH3)2 30"/155-185
NH2
(D-29)
- 41 -

Table I (continued )
Process
Example time/temp.
No . Developer ( sec . / C )
8 30/135-155
~ 1/2 H2S04
NH2
(D-2)
9 ~CH3)2 3o"/l45-l85
~SO2,0 .`
NH2
(D-30)
N (CH3 )2 30"/145-175
3~ 2PTS
NH
(D_4)2
11 HN-C2H5 5"/135-145
~1 . H2S04
NH2
(D-31)
12 NH2 30"/175-200
[~S02CH3
NH2
(D-32)
- 42 -

Table I (continued)
Process
Example time/temp.
No. Developer (sec./C)
. .
13 N02 5"/125-145
PTS
`C~3
NH2
(D-33)
14 5C2 ~ 2H4N(CH3)3Cl 5"/155-175
~O,,~ NDS
CH3
NH2
(D-34)
PTS is p-toluenesulfonic acid3 ~ S03H .
SO H
NDS is 1,5-naphthalenedisulfonic acid 1 3
~. '
S03H
0is ~
If a free base developer is used~ then a suitable
solvent~ sUch as methanol~ is useful to provide a
desired composition.
~ 43 -

Examples 15-21 - Couplers
The procedure described in Exampie 1 was repeated
with the exception that the couplers listed in following
Table II were used in place of the designated coupler of
Example 1. In each instance a dye enhanced silver image
was produced with the exception that 2% gel was used rather
than the 1% in Example 1 and also 30~ ethanol was used
rather than 2% ethanol in Example 1.
- 44 -

Table II
Example No.
NHCOCF3
H O~,OH
' ~zJ
( C-l )
NHCOCH
16 ~f 3
(C-2 )
17 H~[~f)H
NHCOCF3
(C-50 )
NHCOCHC12
18 HO ~,OH
(C-23 )
NHCOCH2CH2Cl
19 F~O ~[~ OH
(C-22 )
NHCOCH2CH2COOH
HO ~,OH
W
(C-51)
COOH
21 H`[~3'OH
(C-40)
- 45 -

~,.1~
Example 22
A dispersion of a silver salt of 3-amino-5-
benzylthio-1,2,4-triazole (ABT) was prepared similar to that
described in Example 1. The resulting dispersion was mixed with
the following components to provide a heat developable
photographic material:
dispersion of silver salt of8.o ml
ABT
silver bromoiodide gelatino emulsion 1.0 ml
(2.5 mole percent iodide, cubic
grain, 0.21 ~ grain)
(10 mg of silver per ml)
4-amino-2-methoxy-N,N,5- 75 mg
trimethylanilinesulfate
(reducing agent) (D-l)
2,6-dihydroxyacetanilide 150 mg
(resorcinol coupler) (C-2)
solvent (95% ethanol, 5% 1.0 ml
methanol)
distilled water 1.0 ml
surfactant (Surfactant lOG 0.2 ml
which is a trade name and a
polyglycidol ether available
from the Olin Corporation, U.S.A.)
The resulting photographic composltion was coated
at a 5 mil wet coating thickness on a gelatin subcoated
poly(ethylene terephthalate) film support. The heat developable
photographic element was then imagewise exposed to light
to provide a developable latent image in the element.
The latent image was developed by uniformly heating the
element by contacting it with a heated metal block at 155C
for 30 seconds. A dye enhanced silver image was developed
having a visual diffuse transmission density of 1.32 and a
-- 46 --
.. . . .
.

minimum density of 0.32.
Examples 23-?7
These are comparative examples.
The procedure described in Example 22 was repeated
with the exception that the described resorcinol coupler was
omitted and each of the following reducing agents was used
individually in place of the described aniline developing agent.
In each instance a silver image was developed in the absence
of dye and the maximum density was significantly less than
that provided by the dye enhanced silver image of Example 22.
Table III
Example
No. Reducing Agent Dmax/Dmin
,
23 t-butylhydroquinone 0.16/0.10
24 ascorbic acid o.76/0.48
4-methyl-4-hydroxy- 0.54/0.30
methyl-l phenyl-3-
pyrazolidone
26 dihydro anhydro- 0.70/0.40
piperldino hexose
reductone
27 4-arnino-2-methoxy-N, 0.66/0.20
N,5-trimethylanlline-
sulfate
Example 28 - Use of silver salt of dodecyltetrazole to
_epare a neutral (black~~image ~~
(A) - Prepara ion of dodecyltetrazole silver salt
To a warm (30C) solution of 9.52 g (0.04 moles) of
5-dodecyltetrazole in 530 ml of acetonitrile was rapidly
added a warm solution of 6.8 g (0.04 moles) of silver nitrate
in 130 ml of acetonitrile. The mixture is diluted with 750 ml
of cool distilled water and the white precipitate filtered and
thoroughly washed with distilled water. The silver salt was
dried overnight (16 hours) at 43~C.
- 47 -
~, . . ~ . .. .

(B) - Preparation of dispersion of silver dodecyltetrazole
3.45 g (0.01 mole) of silver dodecyltetrazole prepared
as above was slurried with 25 ml ethanol. Total weight was
taken to 100 g with distilled water and 4.0 g dry deionized
gelatin added. It was heated with stirring until the gelatin
dissolved. It was then cooled to 20C and mixed thoroughly
using a sonification mixing apparatus with the sample in an
ice-water bath. The resulting dispersion had a pH of 5.9
and a pAg of 6.4.
(C) - Coating preparation
A coating melt was prepared by mixing the following
components:
silver salt dispersion prepared as above 48.o ml
silver bromoiodide gelatino emulsion 9.0 ml
(2.5 mole ~ I, 20 mg Ag/ml)
1,3-dimethyl urea (40% in H20) 2.4 ml
(melt former)
4-amino-N-ethyl-3-methyl-N-(~- 6.o ml
hydroxyethyl)aniline sulfate
(7% in H20) (developing agent)
2',6'-dihydroxytrifluoroacetanilide 3.6 ml
(30% in H20) (coupler) (C-l)
5-amino-1,3,4-thiadiazole-2-thiol 2.4 ml
(0.25% in ethanol) (toner)
Surfactant lOG (10% in H20) (surfactant) o.6 ml
72.0 ml
The resulting composition was coated at 12.0 ml/ft2
on gel-subbed pol~ester film support and dried at 43C.
After imagewise exposure through a step tablet with an Xenon
flash and processing face up for 30 seconds on a hot shoe at
155C, a blue-black image having a visual transmission
_ 48 -
. .,
. .

D-max/D-min of 1.52/0.21 was obtained. The image produced
the D-max readings of 1.48, 1.53, and 1.48 obtained through
blue, green, and red filters respectively.
tD) - Comparative example
A coating was prepared as in (C) without the coupler.
After exposure and processing as above, a low density image
having a visual transmission D-max/D-min of 0.52/0.23 was
obtained. Maximum densities as read through blue, green,
and red filters was 0.75, o.60, and 0.46. Thus, in the
absence of dye enhancement images were obtained that had lower
maximum density and were not neutral (black).
Example 2g - Magenta image with silver salt of ABT
A heat developable photographic element was prepared
similar to that described in Example 28 and containing the
developing agent designated herein as D-l, the resorcinol
coupler designated herein as C-l, and the silver salt of the
compound designated as ABT which is 3-amino-5-benzylthio-1,2,4-
triazole. Upon imagewise exposure to light to provide a
developable latent image followed by uniformly heating the
element to optimum processing temperature, an image was
developed in the element which was magenta in hue. me
maximum density of the developed image (sllver plus dye)
when read through appropriate filters was, respectively,
in the blue, green and red regions of the spectrum: 1.74,
1.58, and l.lg.
Example 30 - Near neutral appearing image with silver salt of ABT
A heat developable photographic element was prepared
similar to that described in Example 28 but containing the
developing agent designated herein as D-2A, the resorcinol
coupler designated herein as C-l, and the silver salt of ABT.
Upon imagewise exposure to light to provide a developable
49

latent image followed by uniformly heating the element to
optimum processing temperature, an image was developed in the
element which was near neutral in appearance. The maximum
density of the developed image (silver plus dye) when read
through appropriate filters was, respectively, in the blue,
green and red regions of the spectrum: 1.39, 1.22, and 1.24.
D-2A herein refers to the compound represented by ;
the formula:
~ 3
CN ~ NH2- H2S04
Example 31 - Neutral (black) image with silver salt of ABT
A heat developable photographic element was prepared
similar to that described in Example 28 but containing
the developing agent designated herein as D-2A, a coupler which
was resorcinol, and the silver salt of ABT. Upon imagewise
exposure to light to provide a developable latent image followed
by uniformly heating the element to optimum processing
temperature, an image was developed (silver plus dye) which was
neutral (black) in appearance. The maximum density of the
developed image (silver plus dye) when read through ~;
appropriate filters was, respectively, in the blue, green
and red regions of the spectrum: 1.46, 1.39, and 1.41. ~ ;.
Examples 28-31 illustrate, among other things, that
with proper selection of developing agent, coupler, silver
halide, silver organic salt, and processing conditions, a
neutral (black) image can be produced, as described.
- 50 -

Examples 32-~7 - Use of silver salt of 1-methYl-4-
imidazoline-2-thione (MITl
.
Silver salt dispersion preparation of l-methyl-4
imidazoline-2-thione, designated herein as MIT. 5.7 grams,
(0.05 mole) of MIT was dissolved in 75 ml of isopropanol
and 125 ml of water in a mechanical blender fitted with a
21C water Jacket. While blending the resulting composition
at a low speed, silver nitrate (6.07 grams, 0.0357 mole)
in 50 ml of water was added quickly and the blending speed
was increased and then continued for 15 minutes until a
stable dispersion resulted. A small concentration of
3-mercapto-1,2,4-triazole (toner) was also added to the
resulting dispersion. One ml of the dispersion (A) contained
10 mg of silver.
A heat developable, photographic silver halide
composition was prepared by mixing the following components:
1.4/1 Dispersion (A) of a silver salt 100 ml
of l-methyl-4-imidazoline-2-thione
(as described)
silver bromoiodide gelatino photographic 10 ml
emulsion (1 ml contains 13 mg of silver)
water 10 ml
15% resorcinol coupler, designated herein 20 ml
as C-2, in methanol)
5~ surfactant in water (Surfactant lOG, 2 ml
a polyglycidol ether available from
Olin Chemical Co., U.S.A.)
Seven ml of the resulting mixture was then mixed with two ml
of 5% by weight aqueous photographic gelatin in which 0.25
mmoles of the developing agent had been dissolved and coated
on gel subbed poly(ethylene terephthalate) film support at
about 50C at a wet coating thickness of 4 mil. The resulting
coating was dried at 150F (65C). After drying, this
photographic element was imagewise exposed to light in a
- 51 -

commercial sensitometer to provide a developable latent image.
The diffuse visual, developed densities as a function of
developing agent are given in the following Table 32A for
processing times resulting in equal fog levels of about
0.2 density units.
- 52 -
-
' ~ ' , ' ' .- : ' ' ;

a
h ~
H h
o s~ s~ O ~ I
a~ bD
h ~ ~ ,D
rl
v ~n
~r) ~1 C\i N N
O ~ O
X \ ~ ~ ~ ~ ~ h
o ~ ~~i,~ ~ ~
~ N C\J r~l
¦ ~--o~ L~ O15~ h
bD u~ L~
P~ ~
3 ~ ~ ~ ~ ~ ~ ~ ~ h
~ CQ ~--a) c~ V K
E~ C) a~ ~ ~ o L~ ~ ~ s~
0 13 ~ V ~ N N p~
o
v ~ ~ ~ h
E3 o
o ~
C) O--`
O q~ ~ ~ _ _ _ .,1 ~ ~ ~
~0 ,~ p~ P; P
O X
-
a,
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~ ~ ~ ~ ~ ~ ft~
X
- 53 --

Examples 38-56 - Use of silver salt of 3-carbox, methy1-4-
meth-y1-4-thiazoline-2-~thlone
A heat developable photographic composition was
prepared by mixing the following components and coating the
resulting material on a support at the noted levels:
dispersion of silver salt of 3-
carboxymethyl-4-methyl-4-thiazoline-
2-thione (designated herein as CMMTT)
(dispersion silver - 64 mg/ft2)
(CMMTT - 167 mg/ft2)
3-mercapto-1,2,4-triazole (toner) 0.93 mg/ft2
2,4-dimercaptopyrimidine (toner) 0.23 mg/ft2
silver iodide 7.0 Agrng/ft2
poly(vinyl alcohol) (binder) 40.0 mg/ft2
The resulting coating contained a CMMTT to silver ion molar ratio
of 1.5 to 1. The coating was overcoated with a solution
of the developing agent designated in the following table
(0.1 mmoles) in 2% by weight aqueous poly(vinyl alcohol) (9.2 ml)
containing a surfactant (Surfactant lOG, o.o6 ml of a 10~ by
20 weight aqueous solution) and resorcinol (90 mg) at a
wet coating thickness of 4 mil at about 90F (32C). l~e
resulting coating was dried at 155F (68C). The heat
developable, photographic element was imagewise exposed to
light in a commercial sensitometer to provide a developable
latent image. The image was developed by uniformly heating the
element. Each element was heated for five seconds. The
elements of Examples 38-52 were uniformly heated at 135C. The
element of Examples 53 and 54 were uniformly heated at 165C.
The element of Example 55 was heated at 185C. The elements
30 containing less active developing agents require higher
processing times and temperatures to produce better images.
- 54 -

~ N ~ N
d o o o
~1 o o
~ ~ ~i
C
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a)
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o U~
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1~ P~ N N ~:
a~ c~
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æ ~ ~ N ~ N ~--
t~) ~
~1
~i o~
- 55 -
,
~, ~
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o ~ ~
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l O O
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¢
C ~ N C\~l
a 5
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bD ~ ~o ~ .
C ~ ~ ~ _~
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~ _~ N
~1
X ~ N
- 56 -

~1
C~ Y~ 3 ~,
H
C¦ N N
Ql O O o
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0~
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_~ p ~1
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0~
C . N C~l
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- 57 --

h
O
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a) (~
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rl N N ~1
l O O O
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o _ ~) ,~ N ~I C ) , N ~1
N~
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- 58 -

g1~3~;
V o~ ~ ~
C ~ N
O O O
~1 o ~D.
~ ,i ,i 0
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N (r
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O /~ /--~ N O~ ~ N O Pi~l /
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o
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Cl
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c
-- 60 --
, .. . . . . . _ .... . . . . . .
:

Example 57 - Use of water insoluble resorcinol cou~ler
.
A heat developable photographic composition was
prepared by mixing the following components:
Surfactant lOG (10~ by weight in water) 0.5 ml
bis(vinylsulfonylmethyl) ether (2% by 1.0 ml
weight in water) (referred to herein
as BVSME)
coupler C-3 (6% by weight latex using 4.0 ml
copoly(n-butyl acrylate 2-acrylamido-
2-methylpropane sulfonic acid) (90:10)
3~ by weight gelatin) (30 mg of coupler
per ml)
D-l developing agent o.o80 g
silver ABT salt (200 g/M gelatin) 8.o ml
(30% ethanol)
silver bromoiodide gelatino emulsion 0.7 ml
(o,843 Kg/Ag mole) (diluted 9:1 with
water) (0.14~ , 2.5 mole % iodide)
The composition was coated at 139.8 mg of silver/ft2 on a
poly(ethylene terephthalate) film support at a wet coating
thickness of 5 mils. The coating was dried at 120F (49C).
The resulting heat developable photographic element was
imagewise exposed to light in a commercial sensitometer
to provide a developable latent image using a 1.5 neutral
density filter. The image was developed by unlformly heatlng
the exposed element on a heated metal block at 160C for
15 seconds. The resulting visible im.age (silver plus dye)
had a diffuse visual maximum density of 1.60 and a
minimum density of 0.28~
0 Exam~le 58 - Use of water insoluble resorcinol coupler and
coupler solven_
A heat developable photographic composition was
prepared by mixing the following components:
- 61 -

water 3.5 ml
surfactant (Surfactant lOG, lQ~ by 0.5 ml
weight in water)
developing agent D-l o.o80 g
resorcinol coupler C-4 (0.260 g in 8.o ml
0.5 ml diethyllauramide and 0.25 ml
ethyl acetate in 16 ml of silver salt
of ABT dispersion, as described, and
milled through a colloid mill)
4-carboxy-4-thiazoline-2-thione 0.004 g
silver bromoiodide gelatino emulsion 0.7 ml
(diluted 9:1 with water) (0.14~,
2.5 mole ~ iodide)
The composition was coated at a 5 mil wet coating thickness
on a polycarbonate film support and dried at 130F (54C).
The resulting heat developable, photographic element was
imagewise exposed to light in a commercial sensitometer
to produce a developable latent image in the element. The
exposed element was then uniformly heated on a heated metal
block at 160C for 30 seconds. The resulting visible image
had a diffuse maximum density as follows using appropriate
filters: red, 1.44; green, 1.57, and blue, 1.61.
C-4 as referred to herein is
O
~ ~ 4Hg-t
~ .
Examples 59-110
A heat developable photographic composition was
pre~ared b~ mixing the following components:
- 62 -

water 1.5 ml
surfactant (Surfactant lOG, 10~ by 0.5 ml
weight in water)
BVSME (2~ by weight in water) 1.0 ml
(hardener)
5-methyl-3-mercapto-1,2,~-triazole 1.0 ml
(antifoggant) (3 mg/ml of water)
ethyl acetate 0.5 ml
resorcinol coupler (as designated in ~.6 m mole
following Table 59A)
developîng agent (as designated in o.o80 g
the following Table 59~) (0.3 m mole)
silver salt of ABT (dispersion, as 8.o ml
described, 200 g/M gelatin, 30
ethanol)
silver bromoiodide gelatino emulsion 0.7 ml
(10 mg Ag)
The composition was coated at a 5 mil wet coating thickness on
a subbed poly(ethylene terephthalate) film support at 120F
(49C). The resulting heat developable, photographic element
was imagewise exposed to light in a commercial sensitometer
to produce a developable latent image. The element was then
uniformly heated on a metal block at 160C for 20 seconds.
The results obtained are given in the followlng table.
,
*Used wlth couplers which ~ere sparingly soluble in water.
- 63 -

a
_ ~ q
m m
X ~ ~ ~ N O 5-~
~ h m m m ~ ~ ~
H ~1 j Li F:l j
O E~
W ~ F~ u N ~D
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V V
V U~
O c~ O ~I N
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- 64 -

E~ ~ ~ C p.
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C ~ o C~ o Xo ~_o
~_,,, o- ~ C~l
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a~ ~
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- 65 -
`'

~ o
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x ~ ~m ~ ,i ~
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- 66 -

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- 67 -

c^
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68

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- 69
. .

~ :" ~ m
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m
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- + 1 ~
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Ll~
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X
-- 70 --
` .. -............... .

c~ - ~ ~
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bD h bD h ~ h ~ ~ D ~ 3: ~ &~
H ~1 ~ ~ 3 U~
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-- 72 --

Cl~ C ~c ~
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o a
bf 1~1
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-- 73 --

o ~
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+ ~ ~ m e~ a) X~ ,I s~
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- 74 -
``.

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a~
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- 75 -
. - . . - , . . .

9~:~
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1-3 ,
-- 76 -

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u~ ~ ,1a) ~
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x ~ o
- 77 -

Example 111
A heat developable, photographic element prepared
as described herein with the silver salt of ABT, developing
agentD-l, and the resorcinol coupler, designated C-l was
imagewise exposed to light in a commercial sensitometer.
The resulting latent image was developed by uniformly heating
the element at 165C for 15 seconds. The following
Dmax/Dmin values (diffuse, transmission) were obtained,
respectively, for the image for the blue, green and
red areas of the spectrum with appropriate filters:
2.21/0.22, 1.98/0.17, and 1.47/0.14.
A comparative element was prepared, exposed, and
processed in the same manner, but without the C-l coupler. The
following Dmax/Dmin values (diffuse, transmission) were
obtained, respectively, for the image for the blue, green
and red areas of the spectrum with the appropriate filters:
1.33/0.18; 0.83/0.13, and 0.66/0.10.
mis illustrates that the heat developable material
containing developing agent D-l and coupler C-l provided
enhanced maximum density and a more neutral lmage hue.
Example 11?
A heat developable photographic element prepared as
described herein with the silver salt of ABT, resorcinol as
the coupler, and the developing agent designated D-2A was
imagewise exposed to light in a commercial sensitometer. The
resulting latent image was developed by uniformly heating the
element at 155C for 30 seconds. me following Dmax values
(diffuse, transmission) were obtained, respectively, for the
- 78 -

image for the blue, green and red areas of the spectrum with
the appropriate filters: 1.70, 1.54, and 1.45.
A comparative element was prepared, exposed,
and processed in the same manner, but without the resorcinol
coupler. The following Dmax values were obtained, respectively,
for the image for the blue, green and red areas of the spectrum
with the appropriate filters: 1.09, 0.72, and 0.53.
This illustrates that the described element containing
the resorcinol coupler produced enhanced maximum image density
and a more neutral tone image than the element without the
resorcinol coupler.
The optimum image will be influenced in many
heat developable materials, as described, by selection of the
most suitable silver halide grain size.
The invention has been described in detail with
particular reference to preferred embodiments thereof, but
it will be understood that variations and modifications can
be effected within the spirit and scope of the invention.
- 79 -
~ .
: