Image forming process including a heating step

An image forming process including a heating step is disclosed. The process comprises conducting said heating step in the presence of at least one compound represented by formula (I), (II), or (III). ##STR1## wherein R.sup.1 represents ##STR2## wherein R.sup.11 and R.sup.12 each represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkyloxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted arylthio group or a substituted or unsubstituted amino group; R.sup.11 and R.sup.12 together form a 5-membered or 6-membered ring; Q represents a hydrogen atom or a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aryl group, or Q represents a group linked to the pyrazole ring, TIME or PUG either directly or through another atom to form a ring; TIME represents a timing group; PUG represents a photographically useful group; and n represents 0 or a positive integer. The image forming process provides for little variation in photographic characteristics even when there is a substantial variation in the heat-processing temperature.

FIELD OF THE INVENTION 
The present invention relates to an image forming process involving a 
heating step, and, more particularly, to an image forming process 
including a heating step which is associated with the use of a precursor 
of a photographically useful reagent. 
BACKGROUND OF THE INVENTION 
Silver halide photography is superior to other photographic methods, such 
as electrophotography and diazo photography, in the photographic 
characteristics that can be achieved, such as sensitivity and tone 
control, and has, therefore, been used most widely. Recent years have 
witnessed development of technology for producing an image more easily and 
quickly by employing a heat-developing process, not relying on the use of 
a developer solution, in lieu of the conventional wet process which 
involves the use of developer and other solutions in the neighborhood of 
room temperature for the processing of a silver halide light-sensitive 
material. 
The heat-developable light-sensitive material is known in this field of art 
and examples of such material and the process involved are described in 
the literature such as The Fundamentals of Photographic Engineering, pp. 
553-555 Corona-Sha, (1979), Image Information, p. 40 (April, 1978); 
Neblette's Handbook of Photography and Reprography, 7th Ed., pp. 32-33 Van 
Nostrand Reinhold Company, (1977). U.S. Pat. Nos. 3,152,904, 3,301,678, 
3,392,020 and 3,457,075, British Pat. Nos. 1,131,108 and 1,167,777 and 
Research Disclosure pp. 9-15, (RD 17029) (June, 1978). 
For the formation of color images by heat-development, a variety of 
processes have been proposed. 
Regarding the formation of a color image through the coupling reaction 
between an oxidized developing agent and a coupler, U.S. Pat. No. 
3,531,286 teaches the use of p-phenylenediamine type reducing agents and 
phenolic or active methylene type couplers; U.S. Pat. No. 3,761,270 
describes p-aminophenol type reducing agents; Belgian Pat. No. 802,519 and 
Research Disclosure p. 31-32 (September, 1975) describe sulfonamidophenol 
type couplers; and U.S. Pat. No. 4,021,240 describes the combination of 
sulfonamidophenol type reducing agents with four-equivalent couplers. 
Regarding the technology of forming a positive color image by the 
photosensitive silver dye bleach method, Research Disclosure pp. 30-32, 
(RD-14433) (April, 1976), Research Disclosure pp. 14-15, (RD-15227) 
(December, 1976), and U.S. Pat. No. 4,235,957, among others, describe 
useful dyes and bleaching methods. 
The methods for forming an image by heat-development comprising the 
utilization of a compound having a built-in dye moiety and adapted to 
release a dye either in correspondence or in reverse correspondence with 
the reduction of silver halide to silver are described in European 
Laid-Open Patent No. 76,492 and No. 79,056 and Japanese Patent Application 
(OPI) Nos. 28928/83, 26008/83 (the term "OPI" as used herein refers to a 
"published unexamined Japanese patent application"). 
Further, the methods for transferring the mobile dye imagewise formed by 
heat-development to an image receiving layer under heating and the 
associated image receiving materials are described in Japanese Patent 
Application (OPI) Nos. 58543/83, 79247/83 and 168439/84, for instance. 
However, in these thermal image forming processes, as the necessary 
photographic reagents are not supplied from a developer solution or the 
like, all the photographic reagents required for development must be 
self-contained within the photographic light-sensitive material itself. 
However, if the photographic reagents are added in their active forms to 
such a photographic light-sensitive material, they may react with the 
other substances contained in the light-sensitive material or be 
decomposed under the influences of heat, oxygen, and the like during 
storage before processing, with the result that they cannot be expected to 
fully display their designed functions. 
One approach toward solving these problems involves blocking the active 
groups of photographic reagents and incorporating them in substantially 
inactive forms, namely as "precursors", in the photographic 
light-sensitive material. 
When a photographically useful reagent in a dye, its functional group which 
would otherwise exert a material influence on its spectral absorption is 
blocked to shift the spectral absorption of the dye toward the short 
wavelength side of the long wavelength side. Then, if the dye is present 
in the same layer as the silver halide emulsion sensitive to the 
corresponding region of the spectrum, the loss of sensitivity due to the 
so-called filter effect can be obviated. 
When the photographically useful reagent is an antifoggant or a development 
inhibitor, blocking its active group results in the suppression of its 
adsorption on the photosensitive silver halide and desensitization due to 
silver salt formation during storage, and as the photographic reagent is 
released at an appropriate time, it can be expected to obtain a fog 
without sacrificing the sensitivity, inhibition of fogging due to 
over-development, and termination of development at the appropriate time. 
When the photographically useful reagent is a developing agent, a 
development auxiliary agent or a coupler, masking its active group or 
adsorbent group enables prevention of photographically undesirable 
influences due to formation of a semiquinone or oxide and prevents 
generation of fog nuclei during storage through prevention of the influx 
of electrons into silver halide, thus contributing to stable processing. 
When the photographically useful reagent is a bleaching accelerator or a 
bleach-fix accelerator, too, blocking its active group leads to the 
advantage that the reaction thereof with other concomitant substances is 
inhibited during storage while the expected function of the reagent may be 
deployed to advantage by unblocking during processing. 
Regarding such technology for blocking photographically useful reagents, 
several specific procedures are known in the field of conventional 
photographic light-sensitive materials. For example, the prior art 
includes the use of acyl or sulfonyl groups as a blocking or masking group 
as described in Japanese Patent Publication No. 44,805/72, the use of 
blocking groups such that photographically useful groups are released by 
the so-called reverse Michael reaction as taught in Japanese Patent 
Publication Nos. 17369/79, 9696/80 and 34927/80, the use of a blocking 
group such that a photographic reagent is released in timed relation with 
the formation of a quinonemethide or quinonemethide-like compound through 
intramolecular electron transfer as described in Japanese Patent 
Publication No. 39727/79, Japanese Patent Application (OPI) Nos. 
135944/82, 135945/82 and 136640/82, the utilization of an intramolecular 
cyclization reaction as described in Japanese Patent Application (OPI) No. 
53330/80, and the use of a ring-opening reaction of a 5-membered or 
6-membered ring system as described in Japanese Patent Application (OPI) 
Nos. 76541/82, 135949/82 and 179842/82. 
However, these known techniques invariably utilize hydrolysis or 
deprotonation due to the action of OH.sup.- in wet development at or near 
room temperature and useful precursor technology has not been known in the 
field of heat development (also referred to as thermal development) using 
an organic base. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide an image forming method 
including a heating step which provides for little variation in 
photographic characteristics even when there is a substantial variation in 
heat-processing temperature by a novel photographically useful reagent 
precursor technology employing a compound which is stable at room 
temperature and adapted to release a photographically useful reagent only 
at a heat-development or heat-transfer stage. 
The above objects have been accomplished by the present invention, which is 
directed to an image forming process involving a heating step which is 
conducted in the presence of at least one compound represented by formula 
(I), (II), or (III). 
##STR3## 
In the above formulae (I), (II), and (III), R.sup.1 represents 
##STR4## 
wherein R.sup.11 and R.sup.12 (which may be the same or different) each 
represents a substituted or unsubstituted alkyl group, a substituted or 
unsubstituted, cycloalkyl group, a substituted or unsubstituted alkenyl 
group, a substituted or unsubstituted aralkyl group, a substituted or 
unsubstituted aryl group, a substituted or unsubstituted heterocyclic 
group, a substituted or unsubstituted alkyloxy group, a substituted or 
unsubstituted aryloxy group, a substituted or unsubstituted alkylthio 
group, a substituted or unsubstituted arylthio group or a substituted or 
unsubstituted amino group, or R.sup.11 and R.sup.12 together form a 
5-membered or 6-membered ring; Q represents a hydrogen atom or a 
substituted or unsubstituted alkyl group, a substituted or unsubstituted 
cycloalkyl group or a substituted or unsubstituted aryl group, or Q 
represents a group linked to the pyrazole ring, TIME, or PUG either 
directly or through another atom to form a ring; TIME represents a timing 
group; PUG represents a photographically useful group; and n represents 0 
or a positive integer.

DETAILED DESCRIPTION OF THE INVENTION 
The implementation of the present invention will hereinafter be described 
in detail. 
In the image forming process including a heating step of the present 
invention, said heating step is conducted in the presence of at least one 
compound represented by formulae (I), (II), and (III). 
##STR5## 
In the above formulae (I) through (III), R.sup.1 represents formula (A), 
(B), or (C). 
##STR6## 
In the above formulae (A), (B), and (C), R.sup.11 and R.sup.12 (which may 
be the same or different) each represents a substituted or unsubstituted 
alkyl group, a substituted or unsubstituted cycloalkyl group, a 
substituted or unsubstituted alkenyl group, a substituted or unsubstituted 
aralkyl group, a substituted or unsubstituted aryl group, a substituted or 
unsubstituted heterocyclic group, a substituted or unsubstituted alkyloxy 
group, a substituted or unsubstituted aryloxy group, a substituted or 
unsubstituted alkylthio group, a substituted or unsubstituted arylthio 
group or a substituted or unsubstituted amino group. Alternatively, 
R.sup.11 and R.sup.12 can together form a 5-membered or 6-membered ring. 
The alkyl group for R.sup.11 and R.sup.12 is preferably a straight-chain 
or branched-chain alkyl group having from 1 to 18 carbon atoms. Specific 
examples thereof include a methyl group, an ethyl group, a n-propyl group, 
a n-butyl group, a n-hexyl group, a n-heptyl group, a 2-ethylhexyl group, 
a n-decyl group, a n-dodecyl group and so on. The cycloalkyl group is 
preferably a 5-membered or 6-membered cycloalkyl group having from 5 to 10 
carbon atoms. Specific examples thereof include a cyclopentyl group, a 
cyclohexyl group and so on. The substituent on the substituted alkyl or 
cycloalkyl group includes a halogen atom, an alkoxy group, an aryloxy 
group, a cyano group, an alkyl- or arylthio group, a disubstituted 
carbamoyl group, an alkyl- or arylsulfonyl group, an alkyl- or 
aryl-disubstituted amino group, a carboxy group, a sulfo group, an 
acylamino group, a sulfonylamino group and so on. 
Examples of the alkenyl group include a vinyl group, an aryl group, a 
crotyl group, and a substituted or unsubstituted styryl group. 
Examples of the aralkyl group include a benzyl group and a .beta.-phenethyl 
group. 
The alkenyl or aralkyl group may have substituents such as mentioned for 
the substituent on the substituted alkyl group. 
The preferred aryl group contains from 6 to 18 carbon atoms. Specific 
examples thereof include a phenyl group, a naphthyl group, an anthryl 
group and so on. The substituent on the substituted aryl group includes a 
substituted or unsubstituted alkyl group, a substituted or unsubstituted 
alkoxy group, a substituted or unsubstituted aryl group, a halogen atom, 
an acylamino group, a sulfonylamino group, a cyano group, a nitro group, 
an alkyl- or arylthio group, an alkyl- or arylsulfonyl group, an 
alkoxycarbonyloxy group, a substituted or unsubstituted carbamoyl group, a 
substituted or unsubstituted sulfamoyl group, an alkyl- or 
aryl-disubstituted amino group, a carboxy group, a sulfo group, an alkyl- 
or aryloxycarbonyl group. 
The preferred heterocyclic group is a 5-membered or 6-membered heterocyclic 
group (the hetero atom or atoms are selected from among O, N, and S). 
Specific examples thereof include a pyridyl group, a furyl group, a 
thienyl group, a pyrrolyl group and an indolyl group. This heterocyclic 
group may have substituents such as mentioned in connection with the 
above-mentioned substituted aryl group. 
Preferred alkyloxy- and aryloxy groups, and alkylthio and arylthio groups, 
are represented by formulae (D) and (E), respectively. 
EQU --OR.sup.13 (D) 
EQU --SR.sup.14 (E) 
Preferred examples of R.sup.13 and R.sup.14 include the same as those 
mentioned hereinbefore for the substituted or unsubstituted alkyl or 
substituted or unsubstituted aryl groups described for R.sup.11 and 
R.sup.12. 
The amino groups R.sup.11 and R.sup.12 may, for example, be --NH.sub.2 or 
an alkyl or aryl-monosubstituted or disubstituted amino group (e.g. a 
dimethylamino group, a diethylamino group, etc.). 
Q represents a hydrogen atom or a substituted or unsubstituted alkyl group, 
a substituted or unsubstituted cycloalkyl group, or a substituted or 
unsubstituted aryl group. Alternatively, Q may be linked to the pyrazole 
ring, TIME, or PUG either directly or through another atom to form a ring. 
Preferred examples of Q include the same groups as those described for the 
substituted or unsubstituted alkyl, cycloalkyl or aryl group referring to 
R.sup.11 and R.sup.12. 
The pyrazole rings of formulae (I), (II), and (III) include those wherein 
the carbon atoms of the pyrazole ring other than the carbon atom having 
the substituent 
##STR7## 
have substituents other than hydrogen atoms. 
Preferred examples of such substituent mentioned just above include those 
described for the substituted aryl group referring to R.sup.11 and 
R.sup.12. 
TIME represents a so-called timing group. 
Typical examples include the group of the formula 
##STR8## 
described in Japanese Patent Publication No. 9696/80 and Japanese Patent 
Application (OPI) Nos. 1139/83 and 1140/83 and the group of the formula 
--OCH.sub.2 --(PUG) described in Japanese Patent Application (OPI) No. 
93442/84. The symbol n represents O or a positive integer, and preferably 
an integer of from 0 to 3. 
PUG represents a photographically useful group. 
The photographically useful groups (PUG) released from the precursor 
compounds are exemplified by antifoggants, development inhibitors, 
developing agents, development accelerators, electron donors (ED), fogging 
agents, nucleating agents, silver halide solvents, bleach accelerators, 
bleach-fix accelerators, fixation accelerators, dyes, color diffusion 
transfer reagents, couplers, melting point depressant agents for use in 
thermographic materials, and coupling inhibitors for use in the diazo 
photothermography. 
Specific examples of antifoggants and development inhibitors include 
nitrogen-containing heterocyclic compounds having mercapto groups. 
The developing agents and development inhibitors include, among others, 
hydroquinones, catechols, aminophenols, p-phenylenediamines, 
pyrazolidones, and ascorbic acid compound. 
The electron donors, fogging agents and nucleating agents include, among 
others, .alpha.-hydroxyketones, .alpha.-sulfonamidoketones, hydrazines, 
hydrazides, tetrazolium salts, aldehydes, acetylenes, quaternary salts, 
and ylides. 
The silver halide solvents are exemplified by thioethers, rhodanines, hypo 
(sodium thiosulfate), methylenebissulfones, and so on. 
The bleach accelerators and bleach-fix accelerators include, among others, 
aminoethanethiols, sulfoethanethiols, aminoethanethiocarbamates, and so 
on. The fixation accelerators are typically represented by hypo. 
The dyes include, for example, azo dyes, azomethine dyes, anthraquinone 
dyes, and indophenol dyes. 
Among the above-mentioned photographically useful groups, those which have 
their effects manifested particularly well when blocked in the form 
represented by any of the formulae (I) to (III) are development 
inhibitors, and the development inhibitors which are especially beneficial 
in this respect are the groups represented by formula (IV). 
##STR9## 
wherein Y represents an atomic group necessary to complete a 5- or 
6-membered heterocyclic ring (preferably containing sulfur, nitrogen, 
and/or oxygen atoms within the ring.) The blocking group is attached to 
the sulfur or nitrogen atom in formula (IV). 
Among the groups represented by formula (IV), those having the following 
formulae are particularly desirable. 
##STR10## 
In the foregoing examples of formula (IV), R.sup.16 represents a member 
selected from the group consisting of a hydrogen atom, an alkyl group, an 
aryl group, a cycloalky group, an alkenyl group and an aralkyl group, and 
these groups may have suitable substituents, such as the substituents 
described above for R.sup.11. The carbon atoms constituting the 
above-given cyclic structures may have substituents other than hydrogen 
atoms, and typical examples of such substituents include those mentioned 
hereinbefore for R.sup.11 and R.sup.12. 
Further, the compound obtainable by blocking a development inhibitor of the 
following formula (IV) in the form shown in any of formulae (I) to (III) 
is also useful. 
EQU R.sup.17 --SH (V) 
(wherein R.sup.17 represents a substituted or unsubstituted alkyl group, a 
substituted or unsubstituted cycloalkyl group, a substituted or 
unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group 
or a substituted or unsubstituted aryl group). The blocking group is 
attached to the sulfur atom in formula (V). 
Examples of the substituent include, for example, an alkyl group, an aryl 
group, a cycloalkyl group, an aralkyl group, an alkoxy group, an aryloxy 
group, an alkylthio group, an arylthio group, an acyl group, an 
alkoxycarbonyl group, an amino group, a N-substituted amino group, an 
acylamino group, a carbamoyl group, a N-substituted carbamoyl group, an 
alkylsulfonyl group, an arylsulfonyl group, an alkylsulfonylamino group, 
an arylsulfonylamino group, a sulfamoyl group, a N-substituted sulfamoyl 
group, a cyano group and a nitro group, a halogen atom, and so on. 
Among these substituents, preferred are an alkyl group, an alkoxy group, an 
aryloxy group, an alkoxycarbonyl group, an acylamino group and a 
sulfonylamino group and a halogen atom. 
Among the compounds of formula (V), those having the following formula 
(V-1) are particularly beneficial. 
##STR11## 
In the above formula (V-1), n represents an integer of 1 to 5; Z represents 
one of the substituents mentioned for R.sup.17 ; provided that when n is 
equal to 2 or more, more than one occurrence of Z may be the same or 
different. 
It should be understood that as the compound of formula (V) has an 
objectionable odor when its molecular weight is low, and has an 
increasingly greater antifoggant effect with an increased hydrophobicity 
of R.sup.17, the number of carbon atoms is preferably at least 6, and, for 
better result, between 10 and 30, inclusive of substituents, if any. 
It is known that mercapto group-containing compounds of formula (IV) or (V) 
exert a development inhibitory effect when used in a silver halide 
photosensitive material, and the use of such compounds in heat-developable 
photosensitive materials is also described, for example in Japanese Patent 
Application (OPI) No. 176351/84 and Japanese Patent Application (OPI) No. 
111636/84. 
However, when the compound of formula (IV) or (V) is directly incorporated 
in the emulsion layer, development is inhibited from the beginning so that 
the image density is decreased and the sensitivity is also reduced at 
times. 
However, when the development inhibitor (IV) or (V) is blocked in the form 
of any of formulae (I) to (III), the development inhibitor (IV) or (V) is 
released gradually during the heat-development so that the development can 
be terminated without incurring decreases in image density. 
Furthermore, by incorporating one of the compounds (I) to (III) according 
to the present invention, which is a blocked development inhibitor (IV) or 
(V), there can be obtained a heat-developable photosensitive material or 
dye fixing material having the property to complement a variation in 
heating temperature. As the development is carried out at a high 
temperature over 100.degree. C., a minor temperature variation is usually 
unavoidable. And as the ultimate image density is high in the high 
temperature area and low in the low temperature area, as a whole an uneven 
image and, especially, an uneveness of fog density tends to be created. 
Moreover, development proceeds at times in the thermal transfer of the 
diffusible dye so that if the fog is increased or the heating temperature 
varies, the transferred image also becomes uneven. 
However, when any of compounds (I) to (III) is incorporated, the 
development inhibitor (IV) or (V) is released in a relatively larger 
amount in the high temperature area and hence, the ultimate local image 
density is suppressed so that, as a whole, the uneveness of image density 
is mitigated. 
The mechanism of action of the compounds (I) to (III) according to the 
present invention appears to be as follows. In the heat-development or 
transfer, the protective (blocking) group R.sup.1 in the 1-position of the 
pyrazole ring is cleaved off under the influence of the nucleophilic agent 
to thereby form an anion (IV) (see the reaction scheme below) and the 
subsequent intramolecular transfer of lone pair electron leads to the 
release of PUG or a dissociated form thereof. 
As an example, the decomposition scheme of the compound (III) is shown 
below. 
##STR12## 
For the cleavage of the blocking group in the 1-position of the pyrazole 
ring, one must presuppose an attack by a nucleophilic reagent. Though the 
identity of this nucleophilic reagent is not clear, one may postulate the 
various terminal residues of amino acid moieties of gelatin, such as 
--NH.sub.2, --OH, --CO.sub.2l H, --SH, 
##STR13## 
It was a surprising discovery that the reaction of the compound according 
to the present invention with said nucleophilic reagent as shown by the 
above scheme takes place effectively in a low water content layer during 
heating in a short space of time. 
Moreover, when a base or a base precursor is used as the development 
accelerator in addition to any of the compounds (I) to (III), the base 
functions as a nucleophilic reagent during heating so as to promote 
release of PUG. For this reason, the combined use of a base or base 
precursor and any of the compounds (I) to (III) according to the present 
invention is particularly advantageous. 
Preferred examples of the base or base precursor which can be used in 
combination with the compounds (I) to (III) according to the present 
invention are set forth below. 
(a) Base 
Preferred examples of the base include, among inorganic bases, the 
hydroxides, secondary or tertiary phosphates, borates, carbonates, 
quinolates and metaborates of alkali metals or alkaline earth metals, 
ammonium hydroxide, quaternary alkylammonium hydroxides, and other metal 
hydroxides, and, among organic bases, aliphatic amines (trialkylamines, 
hydroxylamines, aliphatic polyamines); aromatic amines 
(N-alkyl-substituted aromatic amines, N-hydroxyalkyl-substituted aromatic 
amines, bis[p-dialkylamino)phenyl]methanes, etc.), heterocyclic amines, 
amidines, cyclic amidines, guanidines, cyclic guanidines and so on. 
Particularly preferred are the based with a pKa value of 8 or more. 
(b) Base precursor 
The base precursor includes, among others, the salts of the bases with 
organic acids which are decomposed through decarboxylation upon heating, 
compounds which release amines on decomposition by such reactions as 
intramolecular nucleophilic displacement reaction, Lossen rearrangement, 
Beckmann rearrangement, etc., and compounds which undergo some reaction or 
other upon heating to release a base, to name some preferred examples. To 
be specific, preferred base precursors include the salts of 
trichloroacetic acid which are described in British Pat. No. 998,949, the 
salts of .alpha.-sulfonylacetic acid described in U.S. Pat. No. 4,060,420, 
the salts of propionilic acid described in Japanese Patent Application 
(OPI) No. 180573/84, the 2-carboxycarboxamide derivatives described in 
U.S. Pat. No. 4,088,496, the salts of heat-decomposable acids with organic 
bases or alkali or alkaline earth metals as described in Japanese Patent 
Application No. 69597/83, the hydroxamic acid carbamates utilizing Lossen 
rearrangement as described in Japanese Patent Application (OPI) No. 
168440/84, and the aldoxime carbamates adapted to give rise to nitriles 
when heated as described in Japanese Patent Application (OPI) No. 
157637/84, among others. Aside from the above, the base precursors 
described in British Pat. No. 998,945, U.S. Pat. No. 3,220,846, Japanese 
Patent Application (OPI) No. 22625/75 and British Pat. No. 2,079,480 are 
also useful. 
The ratio of the base precursor to the compound according to the present 
invention is not limited but a preferred molar ratio of the base precursor 
to the compound (I) of the present invention, for instance, is from 1/20 
to 20/1. 
The following is an examplary listing of the compounds (I) through (III) 
according to the present invention. It should be understood, however, that 
the present invention is not limited to the use of these specific 
compounds. 
##STR14## 
The method for synthesizing the compounds of the present invention is 
described below. 
The compound (Q.dbd.H) according to the present invention can be 
synthesized using a methyl-substituted pyrazole (VII) as the starting 
compound. 
##STR15## 
In the foregoing, (wherein X represents halogen atom). 
A general method for production of (VII) is described, for instance, in L. 
C. Behr et al: Pyrazoles, Pyrazolines, Pyrazolidines, Indazoles and 
Condensed Rings, pp. 137-140, Interscience, 1967. 
The halogenation of the side chain in step (a) is conducted using a 
chlorine atom, sulfuryl chloride, a bromine atom, N-chlorosuccinimide, 
N-bromosuccinimide or the like. This reaction is preferably carried out 
with the aid of a radical initiator such as benzoyl peroxide (BPO), 
azobisisobutyronitrile (AIBN) or the like. Frequently, irradiation with 
light is also effective. 
The substitution reaction in step (b) is preferably conducted using an 
inorganic base such as triethylamine or an inorganic base such as 
potassium carbonate. When (PUG) is a compound represented by (IV) or (V), 
it is advantageous to prepare the sodium salt of the thiol, for the 
reaction then proceeds smoothly. 
Specific examples of synthesis are set forth below. 
Synthesis of Compound (7) 
Synthesis of 1-(o-nitrobenzoyl)-3-phenyl-5-methylpyrazole 
This compound was synthesized from o-nitrobenzoylhydrazine and 
benzoylacetone in accordance with the method described in J. Prakt. Chem., 
Vol. 139, p. 65 (1934). 
Synthesis of Compound (7) 
A carbon tetrachloride solution (300 ml) containing 30.7 g (0.1 mole) of 
the above compound, 17.8 g (0.1 mole) of N-bromosuccinimide and 0.3 of 
benzoyl peroxide was refluxed under light irradiation for 5 hours. The 
reaction mixture was then cooled to room temperature and the precipitated 
succinimide was filtered off. The filtrate was distilled under reduced 
pressure and the residue was subjected to thin layer chromatography and 
NMR spectrometry for identification. By these analyses, the product was 
confirmed to be a mixture 5-methyl, 5-bromomethyl and 5-dibromomethyl 
compounds, with the bromomethyl compound accounting for about 70 percent. 
To the above mixture were added 10.5 g (0.7 mole) of 
2-mercaptobenzimidazole, 9.7 g (0.07 mole) of anhydrous potassium 
carbonate and 300 ml of acetone, and the whole mixture was refluxed while 
stirring for 2 hours. 
The inorganic salt was then filtered off and the filtrate was concentrated. 
The concentration residue was purified by silica gel column chromatography 
to provide 18.0 g of Compound (7). 
Yield 57% (based on 2-mercaptobenzimidazole) 
m.p. 92.degree.-95.degree. C. 
While the amount of the compound according to the present invention varies 
with each individual compound and the system in which it is used, it is 
generally up to 50 weight percent on the basis of the weight of the coat 
and preferably up to 30 weight percent on the same basis. The optimum 
amount is largely dependent on the structure of the development inhibitor 
(IV) or (V) that is released. Further, some of the development inhibitors 
(IV) and (V) are such that they accelerate development when used in small 
amounts, but inhibit development when used in increased amounts. 
Therefore, the addition of the compounds (I) to (III) which release such 
compounds (IV) or (V) is especially advantageous, for development is then 
accelerated in an early phase and inhibited in a later phase. 
The compound according to the present invention can be dissolved first in a 
water-soluble organic solvent (for example, methanol, ethanol, acetone, 
dimethylformamide, etc.) or a mixture of such organic solvent and water, 
and then incorporated in the binder. 
The hydrophobic compound according to the present invention can be 
incorporated in microfine particles in the binder by the technique 
described in Japanese Patent Application (OPI) No. 174830/84. While this 
patent literature describes a method for dispersing a base precursor in an 
ultrafine particulate form in the binder, the method is suitable for 
dispersing not only the hydrophobic compound according to the present 
invention, but also other hydrophobic (particularly those sparingly 
soluble in organic solvents) additives such as acid precursors, 
antifoggant precursors, etc., stably in a hydrophilic binder. 
The compounds according to the present invention can be used singly or in 
combination. Furthermore, they may be used in combination with other kinds 
of development inhibitors or in conjunction with other development 
restraining techniques. Known development inhibitors and development 
terminating techniques include a method utilizing heat decomposition of an 
aldoxime ester as described in Japanese Patent Application Nos. 216928/83 
and 48305/84, a method utilizing a Lossen rearrangement reaction as 
described in Japanese Patent Application No. 85834/84, and a method 
utilizing a carboxylic acid ester as described in Japanese Patent 
Application No. 85836/84 among others. 
The terminology "image forming method including a heating step" is used 
herein to mean any photothermographic or thermographic process that 
includes a heating step in any of the image-forming steps, irrespective of 
whether the heating is done for development or for transfer of an image. 
The heat-developable photosensitive material used in the image forming 
process involving a heating step for development includes one using silver 
halide or one using a diazo compound. The compound according to the 
present invention may be incorporated in such a photosensitive material, 
or, when an image receiving layer is provided on a separate support, may 
be incorporated in an optional layer or layers on that support. The 
compound according to the present invention may also be supplied from an 
external source in the heating step. 
In practicing the image forming method including a heating step in 
accordance with the present invention, it is preferable to employ what is 
known to be a heat-developable photosensitive material, inclusive of those 
described in the prior art literature referred to hereinbefore. Thus, 
compounds of formulae (I) to (III) can be incorporated in any of the 
layers existing on the support (for example, the light-sensitive layer, 
intermediate layer, protective layer) or in a material (dye fixing 
element) used for fixation of an imagewise distributed mobile dye. 
The most desirable heat-developable photosensitive material is one 
employing silver halide as a photosensitive substance. 
An appropriate heating temperature is generally from about 50.degree. C. to 
about 250.degree. C., and a particularly useful temperature range is from 
60.degree. C. to 180.degree. C. 
The silver halide that can be used in the practice of the present invention 
can be produced, for example by the method described in U.S. Pat. No. 
4,500,626 and may include the additives mentioned there, and the silver 
halides having the characteristics described there can be employed. 
The silver halide emulsion may be used without ripening, but is generally 
subjected to chemical sensitization. The ordinary emulsions for 
photosensitive materials may be sensitized by sulfur sensitization, 
reduction sensitization and/or noble metal sensitization for use in the 
practice of the present invention. 
The silver halide emulsion used in accordance with the present invention 
may be of the surface latent image type wherein a latent image is 
predominantly formed on the grain surface, or of the internal latent image 
type wherein a latent image is predominantly formed in the interior region 
of the grain. It is also possible to employ a direct reversal emulsion 
made up of an internal latent image emulsion and a nucleating agent. 
The coverage of photosensitive silver halide in the practice of the present 
invention may range from 1 mg to 10 g, as silver, per square meter. 
In the present invention, an organic metal salt, particularly an organic 
silver salt, which is comparatively resistant to light, is preferably used 
as an oxidizing agent in combination with photosensitive silver halide. 
A detailed description of the organic silver salts that can be used is 
given in U.S. Pat. No. 4,500,626. 
The silver halide that is employed in the practice of the present invention 
may be spectrally sensitized with a methine dye or the like. 
For detailed information on such dyes, reference may be made to U.S. Pat. 
No. 4,500,626. 
In the present invention, a reducing agent is incorporated in the 
photosensitive material. As the reducing agent, the reducing dye donors 
described hereinafter, as well as the reducing agents known in the art, 
are preferred. 
As the reducing agents that can be employed in the present invention, those 
described in U.S. Pat. No. 4,500,626 may be mentioned, by way of example. 
In the present invention, there can be incorporated a dye donor compound 
adapted to form or release a mobile dye in accordance or in reverse 
accordance with the reduction of photosensitive silver halide to silver at 
elevated temperature. 
The dye donor compound is described below. 
As examples of the dye donor compounds that can be used in the present 
invention, couplers capable of reacting with the developing agent may 
first be mentioned. The technique of utilizing this type of coupler is 
such that the developing agent oxidized by redox-reaction with the silver 
salt reacts with the coupler to form a dye, and has been described in many 
publications. Specific examples of the developing agents and couplers are 
described in detail, for example in T. H. James: The Theory of the 
Photographic Process, 4th Edition, Macmillan Publishing Co., 1977, pages 
291-334 and pages 354-361, and Shinichi Kikuchi: Shashin Kagaku, 4th 
Edition (Kyoritsu Shuppan), pages 284-295, among others. 
The dye-silver compound, consisting of an organic silver salt and a dye, 
may also be mentioned as an example of said dye donor compound. 
Examples of such dye-silver compound are set forth in Research Disclosure 
pages 54-58 (RD-16966) (May, 1978), among other. 
The azo dye that is used in the heat-development silver dye bleaching 
method can also be mentioned as an example of said dye donor compound. 
Specific examples of such azo dyes and the bleaching technique are 
described in U.S. Pat. No. 4,235,957 and Research Disclosure pages 30-32 
(RD-14433) (April, 1976), among others. 
The leuco dyes described in U.S. Pat. Nos. 3,985,565 and 4,022,617, for 
instance, can also be counted among the dye donor compounds. 
A further example of the dye donor compound include a compound adapted to 
imagewise release or spread a diffusible dye. Compounds of such type can 
be represented by formula [L.sub.1 ] 
EQU (Dye-X)n-Y [L.sub.1 ] 
wherein Dye represents a dye group or a dye precursor group; X represents a 
chemical bond or a divalent linking group; and Y represents a group which 
either causes an imagewise differential in the diffusibility of the 
compound (Dye-X)n-Y in correspondence or reverse correspondence with the 
photosensitive silver salt carrying a latent image or releases the Dye and 
causes a differential in diffusibility between the released Dye and 
(Dye-X)n-Y; n represents 1 or 2 and when n is equal to 2, the two Dye-X 
groups may be the same or different. 
The dye donor compound of general formula [L1] is exemplified by the dye 
developer consisting of a hydroquinone type developer component and a dye 
component which is described in U.S. Pat. Nos. 3,134,764, 3,362,819, 
3,597,200, 3,544,545 and 3,482,972, for instance. The compounds which 
release diffusible dyes through intermolecular nucleophilic substitution 
reaction are described in Japanese Patent Application (OPI) No. 63618/76, 
among others, and the compounds which release diffusible dyes through a 
manner of winding inside the molecule of isooxazolones are described in 
Japanese Patent Application (OPI) No. 111628/74, for instance. 
These systems are invariably such that a diffusible dye is released or 
spread in undeveloped areas and not released or spread in developed areas. 
As an alternative system, there has been developed a system in which a dye 
releasing compound is made into an oxidized form which has no 
dye-releasing property and allowed to be present concomitantly with a 
reducing agent or a precursor thereof, and after development, is reduced 
by the residual unoxidized reducing agent so as to release a diffusible 
dye. Specific examples of the dye donor compounds used in this system are 
set forth in Japanese Patent Application (OPI) Nos. 110827/78, 130927/79, 
164342/81, and 35533/78 among others. 
On the other hand, as the substance which releases a diffusible dye in the 
developed area, the substance which releases a diffusible dye through 
reaction of a coupler moiety having the diffusible dye as a cleavage group 
with an oxidized developing agent is described in Bristish Pat. No. 
1,330,524, Japanese Patent Publication No. 39165/73 and U.S. Pat. No. 
3,443,940, among others, and the substance adapted to form a diffusible 
dye through reaction of a coupler moiety having a non-diffusing group as a 
cleavage group with an oxidized developing agent has been described, for 
example in U.S. Pat. No. 3,227,550. 
Moreover, in these systems employing such color developers, the image 
spoilage by the oxidation products of a developing agent presents a 
serious problem, and, to obtain improvements in this respect, there have 
been developed dye donor compounds which does not require a developing 
agent, but rather have a reducing property per se. 
Typical examples of such dye donor compounds are given in the literature 
noted below. 
The definitions in the respective formulae can be found in the 
corresponding literature. The various dye donor compounds described, for 
example, in U.S. Pat. Nos. 3,928,312, 4,053,312, 4,005,428 and 4,336,322, 
Japanese Patent Application (OPI) Nos. 65832/84, 69839/84, 3819/78 and 
104343/76, Research Disclosure 17465, U.S. Pat. Nos. 3,725,062, 3,728,113, 
and 3,443,939, and Japanese Patent Application (OPI) No. 116537/83 can all 
be employed in the practice of the present invention. 
Specific examples of the dye donor compound that can be employed in the 
present invention are set forth in Japanese Patent Application (OPI) 
84236/84 noted above. 
The dye donor compounds and photographic additives that are employed in 
accordance with the present invention can be incorporated into layers of 
the photosensitive material by the known procedures including the method 
described in U.S. Pat. No. 2,322,027. In such procedures, the high-boiling 
organic solvents and low-boiling organic solvents referred to hereinbefore 
can be employed. 
Moreover, dispersing methods using polymers as described in Japanese Patent 
Publication No. 39853/76 and Japanese Patent Application (OPI) No. 
59943/76 can be utilized. Further, various surfactants can be used in 
dispersing the dye donor compound into a hydrophilic colloid. 
In the practice of the present invention, an image formation accelerator 
can be used in the photosensitive material. The image formation 
accelerators include those which promote the redox reaction between the 
silver salt oxidizing agent and the reducing agent, those which promote 
formation of a dye from a dye donor substance or decomposition of a dye, 
and those which promote various reactions such as the release of a mobile 
dye, and those which accelerate the migration of a dye from a 
photosensitive layer to a dye fixing layer. Classified by physicochemical 
function, the image formation accelerators can be classified into the 
above-mentioned bases or base precursors, nucleophilic compounds, oils, 
thermal solvents, surface active agents, and compounds which interact with 
silver or silver ions, for instance. However, each of these substances 
generally has plural functions and provides several of the above-mentioned 
effects. 
A detailed discussion on these substances and their functions can be found 
in U.S. Pat. No. 4,500,626. 
In the practicing the present invention, various development terminating 
agents can be used in the photosensitive material for the purpose of 
ensuring a constant image quality irrespective of variations in the 
thermal development temperature or processing time. 
The terminology "development terminating agent" as used herein means a 
compound which, after proper development, quickly neutralizes the base or 
reacts with the base to lower the base concentration in the layer and 
thereby terminates the development or a compound which interacts with 
silver and silver salt to arrest development. 
Further, in carrying the present invention into practice, a compound which 
activates development, and, at the same time, serves to stabilize the 
image, can be incorporated in the photosensitive material. 
In the practice of the present invention, an image toner can be 
incorporated in the photosensitive material. Useful examples of the toners 
are mentioned in U.S. Pat. No. 4,500,626. 
The binder used in the photosensitive material according to the present 
invention may be a single binder or a combination of two or more binders. 
Hydrophilic binders can be utilized and typical examples of such binders 
are transparent or translucent binders. More specifically, natural 
substances such as proteins, e.g. gelatin, gelatin derivatives, etc., and 
polysaccharides, e.g., cellulose derivatives, starch, gum arabic, etc., 
and synthetic polymers such as water-soluble polyvinyl compounds, e.g., 
polyvinyl pyrrolidone, polyacrylamide, and so on. Among other synthetic 
polymers that can be used are dispersible vinyl compounds in latex form 
which contribute to the dimensional stability of photographic materials. 
In accordance with the present invention, the binder is used in a coverage 
of 20 g or less per square meter, preferably in a coverage not exceeding 
10 g per m.sup.2, and, for still better results, not more than 7 
g/m.sup.2. 
The proportion of the high-boiling organic solvent which is dispersed 
together with the hydrophobic compound such as said dye donor compound in 
the binder is not more than 1 cc to each gram of the binder, preferably 
not more than 0.5 cc per gram of the binder, and for still better results, 
not more than 0.3 cc on the same basis. 
In the photographic light-sensitive element and dye-fixing element in 
accordance with the present invention, either an inorganic hardener or an 
organic hardener can be incorporated in the photographic emulsion layer 
and/or other binder layer. 
Specific examples of the procedure and of the compounds are set forth in 
U.S. Pat. No. 4,500,626 and these compounds can be used singly or in 
combination. 
The support which is used in the light-sensitive element, and, depending on 
the intended application, in the dye-fixing element as well, may be any 
support that withstands the processing temperature. As the support 
materials, glass, paper, metal and other analogous materials can be 
employed and those mentioned as support materials in U.S. Pat. No. 
4,500,626 can also be utilized. 
When the dye donor used in accordance with the present invention is a donor 
compound adapted to imagewise release a mobile dye, a dye migration 
assisting agent may be used for assisting in the transfer of the dye from 
the light-sensitive layer to the dye fixing layer. 
In a system where a dye migration assisting reagent is supplied from an 
external source, water or a basic aqueous solution containing sodium 
hydroxide, potassium hydroxide, an inorganic metal salt or an organic base 
can be used as the dye migration assisting agent. The base may be those 
mentioned in connection with the image formation accelerator. Moreover, a 
low-boiling solvent such as methanol, N,N-dimethylformamide, acetone, 
diisobutyl ketone, etc., or a mixture of such a low-boiling solvent with 
water or a basic aqueous solution can be employed. The dye migration 
assisting agent may be used in such a manner that it wets either the dye 
fixing element or the light-sensitive element or both. 
When a colored dye-donor compound is contained in the light-sensitive 
element used in the practice of the present invention, it is not so 
necessary to incorporate an anti-irradiation or anti-halation agent and/or 
other dyes in the light-sensitive element but the filter dyes and 
absorbent substances can be incorporated. 
The light-sensitive element employed in the present invention may contain, 
if desired, various additives known in the art of photothermography and 
also include various layers other than light-sensitive layers, such as the 
antistatic layer, conductive layer, protective layer, intermediate layer, 
anti-halation layer, separating layer and so on which are known in the 
art. Examples of additives include the additives described in Research 
Disclosure 170, No. 17029 (June, 1978), such as plasticizers, sharpness 
improving dyes, anti-halation (AH) dyes, sensitizing dyes, matting agents, 
surface active agents, fluorescent whiteners, anti-fading agents, and so 
on, may be mentioned. 
The photographic material according to the present invention comprises a 
light-sensitive material adapted to form or release a dye upon 
heat-development, or, if desired, consists of such a light-sensitive 
element and a dye fixing element. 
Particularly, in a system where an image is formed by the diffusion 
transfer of a dye, both of such light-sensitive and dye-fixing elements 
are necessary, and the system may be classified into two major categories, 
a format in which the light-sensitive element and the dye-fixing element 
are respectively disposed on two independent supports and a format in 
which the two elements are provided as coating layers on one and same 
support. 
As regards the relation between the dye element and dye-fixing element, the 
relation thereof with the support and the relation thereof to the white 
reflective layer, those described in U.S. Pat. No. 4,500,626 are 
applicable to the present invention. 
Representative of the format in which the light-sensitive element and 
dye-fixing element are coated on the same support is the format in which 
the light-sensitive element need not be separated from the image receiving 
element after formation of the transferred image. In this system, the 
light-sensitive layer, dye fixing layer and white reflective layer are 
disposed in superimposition on a transparent or opaque support. A 
preferred example of this format is described in U.S. Pat. No. 4,500,626. 
Another representative format in which the light-sensitive element and dye 
fixing element are disposed on the same support is the format which is so 
designed as to peel apart or all of the light-sensitive element from the 
dye-fixing element, as described in Japanese Patent Application (OPI) No. 
67840/81, Canadian Pat. No. 674,082 and U.S. Pat. No. 3,730,718, for 
instance. 
The light-sensitive element or the dye fixing element may comprise a 
conductive heat element-containing layer as means for heat-development or 
diffusion transfer of the dye. 
The light-sensitive element used in accordance with the present invention 
for the purpose of obtaining a broad range of color within the color chart 
using the three color primaries of yellow, magenta and cyan must have at 
least three silver halide emulsion layers having different spectral 
sensitivities. 
Representative combinations of at least 3 silver halide emulsion layers 
having different spectral sensitivities are described in U.S. Pat. No. 
4,500,626. 
The light-sensitive element used in the practice of the present invention 
may comprise, as required, two or more distinct emulsion layers of the 
same spectral sensitivities but of different speeds. 
The above-mentioned emulsion layers and/or the non-sensitive hydrophilic 
colloid layers adjacent thereto must contain at least a species of the 
substances described in U.S. Pat. No. 4,500,626. 
The light-sensitive element used in accordance with the present invention 
may have, in addition to the above layers, various auxiliary layers as 
necessary, said auxiliary layers such as a protective layer, a 
intermediate layer, an antistatic layer, an anti-curling layer, a 
peel-apart layer, a matting layer and the like. 
Particularly, in the protective layer, it is common practice to incorporate 
an organic or inorganic matting agent for prevention of adhesion. Further, 
a mordant, a ultraviolet absorber and the like may also be incorporated in 
this protective layer. The protective layer and intermediate layer may 
each consist of two or more units. 
In the intermediate layer, a reducing agent may be incorporated for 
preventing mixing of colors, a UV absorber, a white pigment such as 
TiO.sub.2, and so on. The white pigment may be added not only to the 
intermediate layer but also to the emulsion layers for increased 
sensitivity. 
The dye fixing element used in accordance with the present invention has at 
least one layer containing a mordant, and in a format in which the dye 
fixing layer is disposed on the surface, a further protective layer may be 
provided if necessary. 
With regard to the layer construction, binder, additives and the method of 
addition and the position of the mordant in the dye fixing element, those 
described in U.S. Pat. No. 4,500,626 are applicable to the present 
invention. 
The dye fixing element used in the practice of the present invention may 
have separating, matting, anti-curling, and other auxiliary layers, if 
desired, in addition to the above-mentioned layers. 
In one or more layers among the above-mentioned layers, there may also be 
incorporated a base and/or a base precursor for promoting migration of the 
dye, a hydrophilic thermal solvent, an anti-fading agent for preventing 
mixing of colors, a UV absorber, a vinyl compound dispersion for 
increasing the dimensional stability, a fluorescent whitener, and so on. 
The binder to be used in the above-mentioned layers is preferably a 
hydrophilic binder, which is exemplified by transparent and translucent 
hydrophilic colloids. To be specific, the binders mentioned hereinbefore 
in connection with the light-sensivtive element may be employed. 
Further, in its preferred mode, the dye fixing element according to the 
present invention contains an auxiliary image transfer agent which is 
described hereinafter. The auxiliary image transfer agent may be 
incorporated in the dye fixing layer itself or in an independent layer. 
In a system of the present invention wherein electric heating is employed 
as a development means, the transparent or opaque heating element can be 
prepared by known techniques for the production of a resistance heating 
element. 
As the resistance heating element, there is a system employing a thin film 
of semi-conductive inorganic material or a system utilizing a thin film 
comprising a dispersion of conductive fine powders in an organic binder. 
As to the materials that can be used in such systems, those described in 
U.S. Pat. No. 4,500,626 can be utilized. 
Regarding the image receiving layer according to the present invention, it 
may be a dye fixing layer used in a heat-developable color photosensitive 
material, and while a choice may be made from among the mordants commonly 
used, polymeric mordants are particularly preferred. The term "polymeric 
mordant" is used herein to mean any of tertiary amino group-containing 
polymers, nitrogen-containing heterocyclic ring-containing polymers and 
the corresponding quaternary cation group-containing polymers, for 
instance. 
In accordance with the present invention, the coating methods for various 
layers such as a heat-developable light-sensitive layer, a protective 
layer, an intermediate layer, a subbing layer, a backing layer, etc. can 
be as those described in U.S. Pat. No. 4,500,626. 
As the light source for imagewise exposure for recording an image on the 
thermally developable light-sensitive element, various radiations 
including light in the visible region, can be employed, and, for example, 
the sources of light described in U.S. Pat. No. 4,500,626 can be utilized. 
Regarding the heating temperature used in the heat-development process, the 
development can be effected at a temperature between about 80.degree. C. 
to about 250.degree. C. and the particularly useful temperature range is 
from about 110.degree. C. to about 180.degree. C. The heating temperature 
in the transfer process may range from the development temperature to room 
temperature but it is preferable to use a higher temperature, up to about 
10.degree. C. below the heat-development temperature. As the heating means 
for use in the development process and/or the transfer process, use may be 
made of various means such as a hot plate, an iron, a thermal roller, a 
heating element utilizing carbon or titanium white, and so on. 
Further, as described in detail in Japanese Patent Application No. 
218443/84, the method in which development and transfer are carried out 
either at the same time or in a continuous sequence can be advantageously 
utilized. In this method, said image formation promoting agent and/or dye 
migration assisting agent may be previously incorporated in either one or 
both of the dye fixing element and light-sensitive element or supplied 
from the outside. In this system where development and transfer are 
carried out simultaneously or in a continuous sequence, the heating 
temperature is preferably more than 60.degree. C. and less than the 
boiling point of the solvent used for the transfer process. For example, 
when the transfer solvent is water, a temperature between 60.degree. C. 
and 100.degree. C. is preferred. 
The dye migration assisting agent (for example, water) is generally spread 
between the light-sensitive layer of the heat-developable light-sensitive 
element and the dye fixing layer of the dye fixing element to thereby 
accelerate the transfer of the image but it is possible to previously 
apply the dye migration assisting agent to either the light-sensitive 
layer or the dye fixing layer or to both, and then laminate the two 
layers. 
Methods for applying the dye migration assisting agent to the 
light-sensitive layer or the dye fixing layer are described, for example, 
in U.S. Pat. No. 4,500,626. 
The heating means that can be used in the transfer process are described in 
U.S. Pat. No. 4,500,626. As an alternative, one may superimpose a 
conductive layer of graphite, carbon black, or metal on the dye fixing 
material and pass an electric current through the conductive layer so as 
to directly heat the system. 
The heating temperature for use in this transfer process may range from the 
temperature used in the development process to room temperature, but 
preferably more than 60.degree. C. and less than about 10.degree. C. below 
the heat development temperature. 
The pressure conditions and methods for applying the pressure that can be 
used in laminating the heat-developable light-sensitive element to the dye 
fixing element are described in U.S. Pat. No. 4,500,626. 
As the heating step in the present invention is carried out in the presence 
of at least one member selected from the group consisting of compounds of 
formulae (I), (II) and (III), the image forming method according to the 
present invention provides for little variation in photographic 
characteristics even when a variation in heating temperature occurs. 
This is because the above compound is stable at room temperature and has 
the function to release the photographically useful group for the first 
time at the heat-development stage and/or heat-transfer stage. 
The following examples illustrate the present invention in further detail, 
but are not to be construed as limiting the scope of the invention. 
EXAMPLE 1 
The procedure for preparation of a silver iodobromide emulsion is described 
below. 
In 3,000 ml of water were dissolved 40 g of gelatin and 26 g of KBr. This 
solution was stirred at a constant temperature of 50.degree. C. 
Then, a solution of 34 g of silver nitrate in 200 ml of water was added to 
the above solution over a period of 10 minutes. 
Thereafter, a solution of 3.3 g of KI in 100 ml of water was added to the 
above mixture over 2 minutes. 
The pH of the resulting silver iodobromide emulsion was adjusted for 
precipitation and the excess salt was removed. 
Then, the emulsion was adjusted to a pH of 6.0, whereby a silver 
iodobromide emulsion was obtained in a yield of 400 g. 
The procedure for preparation of a gelatin dispersion of a dye donor 
compound is described below. 
Five grams of Yellow Dye Donor Compound (1) and, as a surface active agent, 
0.5 g of 2-ethylhexyl sodium sulfosuccinate and 10 g of tri-iso-nonyl 
phosphate were weighed out, and 30 ml of ethyl acetate was added. The 
mixture was heated at about 60.degree. C. to obtain a homogeneous 
solution. This solution was mixed with 100 g of a 10% solution of 
lime-treated gelatin under stirring and the mixture was homogenized in a 
homogenizer at 10,000 rpm for 10 minutes. This dispersion is designated as 
a yellow dye donor dispersion. 
In the same manner as above except that Magenta Dye Donor Compound (2) was 
used, a magenta dye donor dispersion was prepared. Similarly, a cyan donor 
dispersion containing Cyan Dye Donor Compound (3) was also prepared. 
##STR16## 
The procedure for preparation of a gelatin dispersion of the compound 
according to the present invention is described below. 
To 100 g of a 1% aqueous solution of gelatin was added 3 g of Compound (3) 
according to the present invention and the mixture was ball-milled for 10 
minutes using 100 g of glass beads with a mean diameter of about 0.6 mm. 
The glass beads were filtered off to recover a gelatin dispersion of the 
compound according to the present invention. 
Then, on a support a multi-layer color light-sensitive material A was 
prepared as described below. 
The sixth layer: Layer containing 1,000 mg/m.sup.2 of gelatin, 220 
mg/m.sup.2 of a base precursor*.sup.3, 10 mg/m.sup.2 of Compound (3) of 
the invention. 
The fifth layer: Blue-sensitive emulsion layer containing a silver 
iodobromide emulsion (containing 10 mol% of iodine and 400 mg/m.sup.2 of 
silver), 180 mg/m.sup.2 of benzenesulfonamide*.sup.4, 520 mg/m.sup.2 of a 
base precursor*.sup.3, 5 mg/m.sup.2 of Compound (3) of the invention, 400 
mg/m.sup.2 of Yellow Dye Donor (1), 1,000 mg/m.sup.2 of gelatin, 800 
mg/m.sup.2 of high boiling point solvent*.sup.1, and 100 mg/m.sup.2 of a 
surfactant*.sup.2. 
The fourth layer: Intermediate layer containing 1,200 mg/m.sup.2 of 
gelatin, 200 mg/m.sup.2 of a base precursor*.sup.3, and 10 mg/m.sup.2 of 
Compound (3) of the invention. 
The third layer: Green-sensitive emulsion layer containing a silver 
iodobromide emulsion (containing 10 mol% of iodine and 400 mg/m.sup.2 of 
silver), 180 mg/m.sup.2 of benzenesulfonamide*.sup.4, 10.sup.-6 
mol/m.sup.2 of Sensitizing Dye (D-I), 515 mg/m.sup.2 of a base 
precursor*.sup.3, 5 mg/m.sup.2 of Compound (3) of the invention, 400 
mg/m.sup.2 of Magenta Dye Donor (2), 1,000 mg/m.sup.2 of gelatin, 800 
mg/m.sup.2 of a high boiling point solvent*.sup.1, and 100 mg/m.sup.2 of a 
surfactant*.sup.2. 
The second layer: Intermediate layer containing 1,000 mg/m.sup.2 of 
gelatin, 230 mg/m.sup.2 of a base precursor*.sup.3, and 10 mg/m.sup.2 of 
Compound (3) of the invention. 
The first layer: Red-sensitive emulsion layer containing a silver 
iodobromide emulsion (containing 10 mol% of iodine and 400 mg/m.sup.2 of 
silver), 180 mg/m.sup.2 of benzenesulfonamide*.sup.4, 8.times.10.sup.-7 
mol/m.sup.2 of Sensitizing Dye (D-2), 515 mg/m.sup.2 of a base 
precursor*.sup.3, 5 mg/m.sup.2 of Compound (3) of the invention, 300 
mg/m.sup.2 of Cyan Dye Donor (3), 1,000 mg/m.sup.2 of gelatin, 600 
mg/m.sup.2 of a high boiling point solvent*.sup.1, and 100 mg/m.sup.2 of a 
surfactant*.sup.2. 
Ingredients employed therein are illustrated below. 
##STR17## 
Then, the light-sensitive elements B and C were prepared by substituting 
the Compound (6) and Compound (10) according to the present invention for 
the Compound (3) in the light-sensitive element A. For control purposes, 
the light-sensitive element D free from the compound of the present 
invention was also prepared in the like manner. 
The procedure for preparation of a dye fixing element having an image 
receiving layer is described below. 
First, 0.75 g of gelatin hardener H-1, 0.25 g of gelatin hardener H-2 were 
evenly mixed with 160 ml of water and 100 g of 10% lime-treated gelatin. 
Then, a laminated polyethylene-paper support containing a dispersion of 
titanium oxide was evenly coated with the above mixture in a wet thickness 
of 60 .mu.m, followed by drying. 
Gelatin hardener H-1 
EQU CH.sub.2 .dbd.CHSO.sub.2 CH.sub.2 CONHCH.sub.2 CH.sub.2 NHCOCH.sub.2 
SO.sub.2 CH--CH.sub.2 
Gelatin hardener H-2 
EQU CH.sub.2 .dbd.CHSO.sub.2 CH.sub.2 CONHCH.sub.2 CH.sub.2 CH.sub.2 
NHCOCH.sub.2 SO.sub.2 CH--CH.sub.2 
Then, 15 g of a polymer having the structure shown below was dissovled in 
200 ml of water and the solution was mixed evenly with 100 g of 10% 
lime-treated gelatin. Then, this mixture was spread uniformly in a wet 
thickness of 85 .mu.m in superimposition on the above layer, followed by 
drying. The product was used as a dye fixing element. Polymer 
##STR18## 
(Intrinsic viscosity 0.3473; measured in 1/20 M Na.sub.2 HPO.sub.4 in 
water at 30.degree. C.) 
The above multi-layer color photographic light-sensitive element was 
exposed with tungsten light at 2,000 lux for 10 seconds through blue (B), 
green (G) and red (R) tricolor filters with continuous density variation, 
and then uniformly heated on a heat block at 150.degree. C. or 153.degree. 
C. for 20 seconds. 
The image-receiving elements were immersed in water, and then the above 
heated light-sensitive elements A to D were respectively superimposed on 
the image-receiving elements with the effective layers facing each other. 
After heating on a heat block at 80.degree. C. for 6 seconds, the 
image-receiving element was separated from the light-sensitive element, 
whereby a negative magenta color image was obtained on the image receiving 
element. The density of this negative image was measured with a Macbeth 
reflection densitometer RD-519. The results are set forth in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Heating at 150.degree. C. 
Heating at 153.degree. C. 
Compound No. 
for 20 sec. 
for 20 sec. 
of this Max. 
Min. Max. 
Min. 
Sample No. 
invention 
Filter 
density 
density 
density 
density 
__________________________________________________________________________ 
A (3) B 1.90 
0.14 1.93 
0.16 
(The G 1.98 
0.14 2.00 
0.17 
invention) R 2.05 
0.15 2.08 
0.19 
B (6) B 1.95 
0.18 1.99 
0.21 
(The G 2.02 
0.18 2.06 
0.20 
invention) R 2.09 
0.17 2.11 
0.19 
C (10) B 1.92 
0.15 1.96 
0.19 
(The G 2.00 
0.18 2.04 
0.22 
invention) R 2.08 
0.16 2.10 
0.19 
D None B 1.95 
0.18 2.03 
0.31 
(Control) G 2.04 
0.20 2.16 
0.41 
R 2.12 
0.17 2.30 
0.29 
__________________________________________________________________________ 
It will be apparent from Table 1 that with the compound according to the 
present invention, the increases in maximum and minimum densities are 
small even when the development temperature is higher by 3.degree. C. On 
the other hand, in the case of the control sample free from the compound 
of the present invention, fog is considerably increased. It is, thus, 
evident that the compound according to the present invention has a high 
temperature-complementing effect. 
EXAMPLE 2 
The procedure for preparation of a silver halide emulsion for the fifth 
layer is described below. 
To a well-stirred aqueous solution of gelatin (20 g of gelatin and ammonia 
were dissolved in 1,000 cc of water and the solution was maintained at 
50.degree. C.), there were added an aqueous solution containing potassium 
iodide and potassium bromide (1,000 ml) and a solution of silver nitrate 
(1 mole of silver nitrate dissolved in 1,000 ml of water) concurrently 
white pAg was maintained constant, to provide a monodisperse octahedral 
silver iodobromide emulsion (iodine content: 5 mol %) with a mean grain 
size of 0.5 .mu.m. 
After washing and desalting, 5 mg of chloro-auric acid (4H.sub.2 O) and 2 
mg of sodium thiosulfate were added to carry out the gold-sulfur 
sensitization at 60.degree. C. 60.degree. C. The yield of the emulsion was 
1.0 kg. 
The procedure for preparation of an emulsion for the third layer is 
described below. 
To a well-stirred aqueous solution of gelatin (20 g of gelatin and 3 g of 
sodium chloride were dissolved in 1,000 ml of water and the solution was 
held at 75.degree. C.) were added an aqueous solution containing sodium 
chloride and potassium bromide (600 ml), an aqueous solution of silver 
nitrate (0.59 mole of silver nitrate in 600 ml of water) and the dye 
solution (I) described below over a period of 40 minutes, concurrently in 
constant appropriate portions. The above procedure provided a monodisperse 
cubic silver chlorobromide emulsion (bromine content: 80 mol %) having dye 
adsorbed thereto and with a mean grain size of 0.35 .mu.m. 
After washing and desalting, 5 mg of sodium thiosulfate and 20 mg of 
4-hydroxy-6-methyl-1,3-3a,7-tetrazaindene were added for chemical 
sensitization at 60.degree. C. The yield of the emulsion was 600 g. 
##STR19## 
The procedure for preparation of an emulsion for the first layer is 
described below. 
To a well-stirred aqueous solution of gelatin (20 g of gelatin and 3 g of 
sodium chloride were dissolved in 1,000 ml of water and the solution was 
held at 75.degree. C.) were added an aqueous solution containing sodium 
chloride and potassium bromide (600 ml) and an aqueous solution of silver 
nitrate (0.59 mole of silver nitrate in 600 ml of water) over a period of 
40 minutes, concurrently in constant appropriate portions. The above 
procedure gave a monodispersive cubic silver chloro-bromide emulsion 
(bromine content: 80 mol %) having the dye adsorbed and with a mean grain 
size of 0.35 .mu.m. 
After washing and desalting, 5 mg of sodium thiosulfate and 20 mg of 
4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene were added for chemical 
sensitization at 60.degree. C. The yield of the emulsion was 600 g. 
The procedure for preparation of a benzotriazole silver emulsion is 
described below. 
In 3,000 ml of water were dissolved 28 g of gelatin and 13.2 g of 
benzotriazole and the solution was stirred at a constant temperature of 
40.degree. C. To this solution was added a solution of 17 g of silver 
nitrate in 100 ml of water over a period of 2 minutes. 
The pH of the above benzotriazole silver emulsion was adjusted to cause 
precipitation and the excess salt was removed. Then, the emulsion was 
adjusted to a pH of 6.0 to provide 400 g of benzotriazole silver emulsion. 
A dispersion of the color donor compound was prepared in the same manner as 
Example 1. 
Using the above, a multi-layer color light-sensitive element E was prepared 
on a support as described below. 
The sixth layer: Layer containing 740 mg/m.sup.2 of gelatin, and 250 
mg/m.sup.2 of a base precursor (A)*.sup.3. 
The fifth layer: Blue-sensitive emulsion layer containing a silver 
iodobromide emulsion (containing 5 mol% of iodine and 500 mg/m.sup.2 of 
silver), 160 mg/m.sup.2 of benzenesulfamide, 270 mg/m.sup.2 of a base 
precursor (A)*.sup.3, benzotriazole silver emulsion (300 mg/m.sup.2 of 
silver), 400 mg/m.sup.2 of Yellow Dye Donor (1), 1,200 mg/m.sup.2 of 
gelatin, 700 mg/m.sup.2 of high boiling point solvent*.sup.1, and 70 
mg/m.sup.2 of a surfactant*.sup.2. 
The fourth layer: Intermediate layer containing 700 mg/m.sup.2 of gelatin 
and 240 mg/m.sup.2 of a base precursor (A)*.sup.3. 
The third layer: Green-sensitive emulsion layer containing a silver 
chlorobromide emulsion (containing 80 mol% of bromine, and 200 mg/m.sup.2 
of silver), 140 mg/m.sup.2 of benzenesulfamide, a benzotriazole silver 
emulsion (100 mg/m.sup.2 of silver), 210 mg/m.sup.2 of a base precursor 
(A)*.sup.3, 330 mg/m.sup.2 of Magenta Dye Donor (2), 860 mg/m.sup.2 of 
gelatin, 430 mg/m.sup.2 of a high boiling point solvent*.sup.1, and 60 
mg/m.sup.2 of a surfactant*.sup.2. 
The second layer: Intermediate layer containing 1,000 mg/m.sup.2 of 
gelatin, and 240 mg/m.sup.2 of a base precursor (A)*.sup.3. 
The first layer: Red-sensitive emulsion layer containing a silver 
chlorobromide emulsion (containing 80 mol% bromine and 200 mg/m.sup.2 of 
silver), 140 mg/m.sup.2 of benzenesulfamide, 8.times.10.sup.-7 mol/m.sup.2 
of Sensitizing Dye*.sup.4, benzotriazole silver emulsion (230 mg/m.sup.2 
of silver), 230 mg/m.sup.2 of a base precursor (A)*.sup.3, 300 mg/m.sup.2 
of Cyan Dye Donor (3), 850 mg/m.sup.2 of gelatin, 540 mg/m.sup.2 of a high 
boiling paint solvent*.sup.1, and 60 mg/m.sup.2 of a surfactant*.sup.2. 
Ingredients employed therein are illustrated below. 
##STR20## 
The procedure for preparation of the dye fixing element is described below 
In 200 ml of water was dissolved 12 g of lime-treated gelatin followed by 
addition of 16 ml of a 0.5M aqueous solution of zinc acetate with 
stirring. The homogeneous mixture was then evenly coated on a 100 
.mu.m-thick white support of titanium dioxide-containing polyethylene 
terephthalate film in a wet thickness of 85 .mu.m. On top of the resulting 
layer, the following coating composition was further coated in a wet 
thickness of 90 .mu.m followed by drying to provide a dye fixing element. 
______________________________________ 
Dye fixing layer composition F: 
Polyvinyl alcohol 120 g 
(degree of polymerization: 2,000), 
10% aqueous solution 
Urea 20 g 
Nmethylurea 20 g 
##STR21## 80 g 
(intrinsic viscosity 0.1726, 
measured in aqueous NaCl at 30.degree. C.) 
Compound (3) of the invention 
60 ml 
(described in Example 1) 
Dye fixing layer composition G: 
Polyvinyl alcohol 120 g 
(degree of polymerization: 2,000), 
10% aqueous solution 
Urea 20 g 
Nmethylurea 20 g 
##STR22## 80 g 
Water 60 ml 
______________________________________ 
The above multi-layer color light-sensitive element was exposed with 
tungsten light at 2,000 lux for 1 second through the B, G, and R tricolor 
filters with continuous density variation and, then, uniformly heated on a 
heat block at 150.degree. C. for 20 seconds. 
This light-sensitive material was then laminated to the dye fixing element 
prepared above and after pressing and passage over a heat roller at 
130.degree. C., immediately heated on a heat block at 120.degree. C. for 
30 seconds. Immediately after heating, the dye fixing element was 
separated from the light sensitive element, whereupon yellow, magenta, and 
cyan-colored images were obtained in correspondence with the tricolor 
filters B, G, R on the dye fixing element. The maximum and minimum density 
values of each color were measured with a Macbeth reflection densitometer 
RD 519. The results are shown below. 
TABLE 2 
______________________________________ 
Dye fixing layer F 
Dye fixing layer G 
(The invention) 
(Comparison) 
Color Max. Min. Max. Min. 
filter density density density 
density 
______________________________________ 
B 1.87 0.20 1.90 0.28 
G 2.11 0.17 2.12 0.32 
R 2.20 0.18 2.25 0.29 
______________________________________ 
It is clear from the above results that the incorporation of the compound 
according to the present invention in the dye fixing layer inhibits an 
increase of fog during the transfer process. 
EXAMPLE 3 
Ten grams of dye donor compound (4), 0.5 g of 2-ethylhexyl sodium 
sulfosuccinate and 10 g of tricresyl phosphate were weighed and 20 ml of 
cyclohexanone was added. The mixture was heated at 60.degree. C. to 
provide a homogeneous solution. This solution was mixed with 100 g of a 
10% aqueous solution of lime-treated gelatin with stirring and dispersed 
in a homogenizer. 
Then, a light-sensitive element H was prepared in the following manner. 
______________________________________ 
(a) The silver iodobromide 5.5 g 
emulsion of Example 1 
(b) 10% Aqueous gelatin solution 
0.5 g 
(c) The above dye donor compound 
2.5 g 
dispersion 
(d) Guanidine trichloroacetate, 
1 ml 
10% in ethanol 
(e) 2,6-Dichloro-4-aminophenol, 
0.5 ml 
10% in methanol 
(f) The following compound, 1 ml 
5% in water 
##STR23## 
(g) Compound (3) of the invention, 
0.5 ml 
dispersed in gelatin 
(h) Water 6 ml 
##STR24## 
______________________________________ 
The above components (a) to (h) were mixed and dissolved by heating and the 
solution was coated on a polyethylene terephthalate film in a wet 
thickness of 85 .mu.m. 
On top of this layer was further coated a gelatin protective layer in a 
coverage of 1.5 g/m.sup.2 to provide a light-sensitive element H. This 
light-sensitive element H was imagewise exposed with tungsten light at 
2,000 lux for 10 seconds and evenly heated on a heat block at 140.degree. 
C. or 143.degree. C. for 30 seconds. 
The above element was further subjected to the same procedure as Example 1. 
The results were as set forth in Table 3. 
TABLE 3 
______________________________________ 
Heating at 140.degree. C. 
Heating at 143.degree. C. 
for 30 sec. for 30 sec. 
Max. Min. Max. Min. 
density density density density 
______________________________________ 
H 2.02 0.18 2.04 0.20 
______________________________________ 
The above results indicate that the effect of the compound according to the 
present invention is remarkable even in a photosensitive material 
containing a dye donor compound adapted to release a dye upon coupling 
with an oxidized developing agent. 
EXAMPLE 4 
To 5 g of a dye donor compound having the following structure (5), 4 g of 
an electron donor compound having the following structure, 0.5 g of 
2-ethylhexyl sodium sulfosuccinate, and 10 g of tricresyl phosphate was 
added 20 ml of cyclohexanone and the mixture was heated at about 
60.degree. C. The resulting solution was thereafter treated in the same 
manner as Example 3, to provide a reducible dye donor compound dispersion. 
##STR25## 
The procedure of Example 3 was repeated except the above-mentioned 
reducible dye donor dispersion was used in lieu of the dye donor (4) 
dispersion in the light-sensitive element (H) to provide a light-sensitive 
element (I). 
This light-sensitive element was exposed and processed in the same manner 
as Example 3. The results are shown below. 
TABLE 4 
______________________________________ 
Heating at 140.degree. C. 
Heating at 143.degree. C. 
for 30 sec. for 30 sec. 
Max. Min. Max. Min. 
density density density density 
______________________________________ 
I 1.78 0.18 1.82 0.21 
______________________________________ 
It is seen that the compound according to the present invention is also 
useful in a photosensitive material containing a reducible dye donor 
compound adapted to yield a positive image relative to the silver image. 
EXAMPLE 5 
Procedure for preparation of a gelatin dispersion of the coupler 
Five grams of 2-dodecylcarbamoyl-1-naphthol, 0.5 g of 2-ethylhexyl sodium 
sulfosuccinate and 2.5 g of tricresyl phosphate (TCP) were weighed and 30 
ml of ethyl acetate was added. The resulting solution was mixed with 100 g 
of a 10% solution of gelatin and dispersed in a homogenizer at 10,000 rpm 
for 10 minutes. 
A light-sensitive element J was prepared in the following manner. 
______________________________________ 
(a) Silver iodobromide emulsion 
10 g 
(The emulsion of Example 1) 
(b) Gelatin dispersion of coupler 
3.5 g 
(c) 0.25 g of Guanidine trichloroacetate 
2.5 cc 
dissolved in 2.5 cc of ethanol 
(d) Gelatin (10% aqueous solution) 
5 g 
(e) 2,6-Dichloro-p-aminophenol 
0.2 g 
(dissolved in 15 cc of water) 
(f) Gelatin dispersion of Compound (3) 
1 ml 
of the invention (as described 
in Example 1) 
______________________________________ 
The above composition was coated on a polyethylene terephthalate support in 
a wet thickness of 60 .mu.m followed by drying to provide a 
light-sensitive element. 
This light-sensitive element was imagewise exposed with tungsten light at 
2,000 lux for 5 seconds. Then, the exposed element was uniformly heated on 
a heat block at 150.degree. C. or 153.degree. C. for 20 seconds, whereupon 
a negative cyan color image was obtained. The density of the color was 
measured with a Macbeth transmittance densitometer TD-504. The results 
were as follows. 
TABLE 5 
______________________________________ 
Heating at 150.degree. C. 
Heating at 153.degree. C. 
for 20 sec. for 20 sec. 
Max. Min. Max. Min. 
density density density density 
______________________________________ 
J 2.05 0.21 2.08 0.24 
______________________________________ 
It is apparent that the compound according to the present invention has a 
high temperature complementing effect. 
EXAMPLE 6 
An example of the invention in black-and-white photography is given below. 
A light-sensitive element K was prepared in the following manner. 
______________________________________ 
(a) Silver iodobromide emulsion 
1 g 
(the emulsion of Example 1) 
(b) Benzotriazole silver emulsion 
10 g 
(the emulsion of Example 2) 
(c) Guanidine trichloroacetate 
1 cc 
(10% in ethanol) 
(d) A compound of the following 
2 cc 
structural formula, 5% in 
methanol 
##STR26## 
(e) Compound (3) of the invention, 
1 cc 
as dispersed in gelatin 
(described in Example 1) 
______________________________________ 
The above composition was coated on a polyethylene terephthalate support in 
a wet thickness of 60 .mu.m, followed by drying. 
The above light-sensitive element was imagewise exposed with tungsten light 
at 2,000 lux for 5 seconds. Then, the element was uniformly heated on a 
heat block at 130.degree. C. or 133.degree. C. for 30 seconds, whereupon a 
negative brown image was obtained. The density of the image was measured 
with a Macbeth transmission densitometer TD-504. The results are as 
follows. 
TABLE 6 
______________________________________ 
Heating at 130.degree. C. 
Heating at 133.degree. C. 
for 30 sec. for 30 sec. 
Max. Min. Max. Min. 
density density density density 
______________________________________ 
K 0.80 0.16 0.83 0.19 
______________________________________ 
It is apparent that the compound according to the present invention has a 
remarkable high temperature-complementing effect. 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the 
art that various changes and modifications can be made therein without 
departing from the spirit and scope thereof.