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Description  |
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This application is related to: application Ser. No. 608,006, filed Aug.
26, 1975, now U.S. Pat. No. 4,036,650, issued July 10, 1977 which was
copending with parent application Ser. No. 643,810; application Ser. No.
599,061 filed July 25, 1975, now U.S. Pat. No. 4,069,759, issued Jan. 24,
1978 and Ser. No. 685,460, filed May 12, 1976, now U.S. Pat. No.
4,057,016, issued Nov. 8, 1977.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a heat developable photosensitive composition
containing an organic silver salt and a heat developable photosensitive
member having a layer comprising the composition.
2. Description of the Prior Art
Photosensitive materials for forming silver images have been widely used
and can give high quality of images which can be formed at high
sensitivity. As the materials for forming silver images, there are usually
known materials including organic silver salts as well as conventional
silver halide emulsion. The silver image forming heat developable
photosensitive materials including organic silver salts can be developed
by a heat treatment alone after imagewise exposure. These silver image
forming heat developable photosensitive materials can easily form images,
in particular, the images can be formed by a dry process, and therefore,
these materials have various advantages different from those resulting
from conventional silver halide emulsions of a wet developing type and are
expected to have wide application fields.
Such heat developable photosensitive material comprising an organic silver
salt contains an organic silver salt and a halide as its essential
components. The image formation is carried out by imagewise exposure of
the heat developable photosensitive material and then heat development. In
detail, the imagewise exposure causes a photochemical reaction of the
halide with the organic silver salt to isolate a small amount of silver
resulting in the formation of a latent image, and the small amount of
silver thus isolated can be nucleus for developing the silver isolated
from the organic silver salt by the subsequent developing procedure to
produce a silver image at the exposed portions and thus complete the
formation of a visible image.
These heat developable photosensitive materials comprising an organic
silver salt usually do not have a high sensitivity because the materials
are not mainly composed of a photosensitive substance of high sensitivity
as in case of conventional silver halide emulsions, and further the
original photosensitive composition remains at the non-exposed portion
without subjecting to any change and therefore, isolation of silver at the
non-exposed portion (non-image portion) is observed upon heat development,
and it is very difficult to produce images of so high contrast as in case
of a silver halide emulsion. In addition, even after the formation of
images (silver images), the non-exposed portions have the same composition
as that of the original (before exposure) photosensitive composition, and
therefore, isolation of silver from the remaining organic silver salt is
observed. In fact, fogging phenomenon is observed after the formation of
images. Consequently, it is not possible to maintain the image quality
(particularly, contrast) obtained upon the image formation, and the image
stability is not sufficiently high.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a heat developable
photosensitive composition which comprises an organic silver salt, a
halide, and at least one member selected from the class of sulfur
compounds, and also there is provided a heat developable photosensitive
member which comprises a layer containing the above mentioned heat
developable photosensitive composition and a reducing agent.
According to the present invention, there is provided a heat developable
photosensitive member which comprises a layer containing the above
mentioned heat developable photosensitive composition and a layer
containing a reducing agent, the latter layer overlying the former layer.
An object of the present invention is to provide a heat developable
photosensitive composition comprising mainly an organic silver salt free
from the above-mentioned drawbacks.
Another object of the present invention is to provide a heat developable
photosensitive composition capable of producing a high image contrast.
A further object of the present invention is to provide a heat developable
photosensitive composition in which the isolation of silver from the
organic silver salt at the exposed portion is accelerated upon heat
developing while the isolation at the non-exposed portion is suppressed.
Still another object of the present invention is to provide a heat
developable photosensitive composition in which the isolation of silver
from the remaining organic silver salt after the completion of formation
of images (after development) is suppressed to maintain the image quality
at the time of said formation of images without any change.
Still another object of the present invention is to provide a heat
developable photosensitive member of high sensitivity and high resolving
power having a layer containing the above mentioned heat developable
photosensitve composition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The sulfur compounds used in the present invention are compounds having the
following formulas (1)-(6):
##STR1##
In the above formulas, Y is selected from the class of hydrogen, alkyl,
unsubstituted or substituted phenyl, aralkyl, and
##STR2##
where R.sub.7 is selected from alkyl having 1-4 carbon atoms and benzyl.
The alkyl is preferably an alkyl having 1-6 carbon atoms.
Z is one or more atoms necessary for forming a 5- or 6- membered
heterocyclic ring which may be unsubstituted or substituted, for example,
in case of the formula (1), benzthiazole ring, benzoxazole ring and
benzimidazole ring, and in the formula (2), thiazoline ring, imidazole
ring, imidazoline ring, triazole ring, pyrroline ring, pyridine ring,
thiadiazole ring, thiadiazoline ring, pyrazole ring, pyrimidine ring and
oxadiazole ring.
R.sub.1 and R.sub.2 are selected from the class of alkyl, unsubstituted or
substituted phenyl and aralkyl. R.sub.1 and R.sub.2 may be similar or
dissimilar, preferably similar. The alkyl is preferably an alkyl having
1-8 carbon atoms and the aralkyl is preferably benzyl.
R.sub.3 is selected from the class of alkyl, preferred with an alkyl having
1-8 carbon atoms, and aralkyl, preferred with benzyl.
R.sub.4 is selected from the class of alkyl, unsubstituted or substituted
phenyl and aralkyl, and it is preferably an alkyl having 1-8 carbon atoms,
unsubstituted phenyl, phenyl substituted by nitro, methyl, methoxy,
halogen etc., and benzyl.
R.sub.5 and R.sub.6 are, similar or dissimilar, alkylene, preferably an
alkylene having 1-8 carbon atoms.
x is an integer of 1-4.
The addition of a sulfur compound to a heat developable photosensitive
composition comprising an organic silver salt as disclosed in the present
invention results in production of fogless and high contrast images and
high stability. In particular, as is shown in the Examples, the sulfur
compounds of formulas (1), (2), (3), (4), (5) and (6) accelerate isolation
of silver at exposed portions and suppress isolation of silver at
non-exposed portions in the process of forming images, and further
suppress spontaneous isolation of silver from the organic silver salt at
any portions after formation of images to maintain the original image
quality. The sulfur compound according to the present invention has
excellent effects and is an additive different from and better than
conventional image stabilizers, sensitizers, and image quality controlling
agents.
The sulfur compounds of formulas (1), (2), (3), (4), (5) and (6) have the
desired effects regardless of types of the organic silver salts.
The amount of the sulfur compound of formula (1), (2), (3), (4), (5), or
(6) is usually 10.sup.-4 -10.sup.-1 part by weight per one part by weight
of the organic silver salt compound, and preferred with 5.times.10.sup.-4
-10.sup.-2 by weight.
Representative sulfur compounds of formulas (1), (2), (3), (4), (5) and (6)
are as shown in Tables 1, 2, 3, 4, 5 and 6, respectively.
Table 1
__________________________________________________________________________
Sulfur compounds of formula (1)
Compound
__________________________________________________________________________
##STR3## 2-mercaptobenzothiazole
##STR4## 2-phenylmercaptobenzothiazole
##STR5## 2-(p-chlorophenylmercapto) benzothiazole
##STR6## 2(2,4-dinitrophenylmercapto) benzothiazole
##STR7## 2-mercapto-4,5-benzo-1,3-thiazine
##STR8## 2-mercaptobenzoxazole
##STR9## 2-(p-nitrophenylmercapto) benzoxazole
##STR10## 2-mercaptobenzimidazole
##STR11## diethyldithiocarbamic acid 2-benzothiazolyl
ester
##STR12## dibenzyldithiocarbamic acid 2-benzothiazolyl
ester
##STR13## dimethyldithiocarbamic acid 2-benzimidazolyl
ester
##STR14## 2-butylmercaptobenzothiazole
##STR15## 2-cyclohexylmercapto- benzoxazole
##STR16## 2-methylmercaptobenzimidazole
##STR17## 2-propylmercaptobenzothiazole
##STR18## 2-pentylmercaptobenzoxazole
##STR19## dipropyldithiocarbamic acid 2-benzothiazolyl
ester
##STR20## dibutyldithiocarbamic acid 2-benzimidazolyl
ester
##STR21## 2-hexylmercaptobenzothiazole
__________________________________________________________________________
Table 2
__________________________________________________________________________
Sulfur compounds of formula (2)
Compound
__________________________________________________________________________
##STR22## 2-mercaptothiazoline
##STR23## 2-mercaptoimidazole
##STR24## 2-methylmercaptoimidazole
##STR25## 2-methylmercapto-4,5- diphenylimidazole
##STR26## 1-methyl-5-nitro-2- methylmercaptoimidazole
##STR27## 2-mercaptoimidazoline
##STR28## 2-methylmercaptoimidazoline
##STR29## 1-phenyl-2-methylmercapto-4,4- dimethyl-5-imidazoli
ne
##STR30## 1-phenyl-3-mercapto-4,5- dimethylpyrazole
##STR31## 3-methylmercapto-1,5- dimethylpyrazole
##STR32## 1-phenyl-3-methylmercapto-5- methylpyrazole
##STR33## 2-methylmercaptothiazoline
##STR34## 2-ethylmercaptothiazole
##STR35## 3-propylmercapto-1,5- dimethylpyrazole
##STR36## 2-butylmercaptothiazoline
##STR37## 2-pentylmercaptoimidazoline
##STR38## 2-hexylmercaptoimidazole
##STR39## 2-phenylmercaptothiazoline
##STR40## 2-benzylmercaptoimidazole
##STR41## diethyldithiocarbamic acid 2-imidazolyl ester
##STR42## 4,6-dichloro-2- methylmercaptopyrimidine
##STR43## 2-methylmercapto-4,6- dimethylpyrimidine
##STR44## 4-chloro-2- benzylmercaptopyrimidine
##STR45## 2-ethylmercaptopyrimidine
##STR46## 6-(2,4-dinitrophenylmercapto)-4- methyl-2-pyrimidon
e
##STR47## 1-benzyl-2-ethylmercapto-4- pyrimidone
##STR48## 2-benzylmercapto-4-pyrimidone
##STR49## 3-benzylmercapto-1,5-diphenyl- 1,2,4-triazole
##STR50## 1-methyl-5-mercapto-3-phenyl- 1,2,4-triazole
##STR51## 1-methyl-5-phenylmercapto-3- phenyl-1,2,4-triazole
.
##STR52## 5-methylmercapto-1,3-diphenyl- 1,2,4-triazole
##STR53## 2-methylmercaptopyrroline
##STR54## 2-mercaptopyridine
##STR55## 2-methylmercaptopyridine
##STR56## 3-phenyl-5-mercapto- 1,2,4-thiadiazole
##STR57## 5-phenyl-2-mercapto- 1,3,4-thiadiazole
##STR58## 5-phenyl-2-p-nitrophenylmercapto- 1,3,4-thiadiazole
##STR59## 2-benzylmercapto-1,3,4- thiadiazole
##STR60## 4-phenyl-2-methylmercapto- 1,3,4-thiadiazoline
##STR61## 5-ethylmercapto-2,3- diphenyl-1,3,4-thiadiazoline
##STR62## 3-phenyl-5-mercapto-2-methyl- 1,3,4-thiadiazoline
##STR63## 4-phenyl-2-mercapto-1,3,4- thiadiazoline
##STR64## 3-phenyl-5-methylmercapto- 1,3,4-thiadiazoline-2-on
e
##STR65## 3-phenyl-5-mercapto-1,2,4- oxadiazole
##STR66## 3-phenyl-5-mercapto-1,3,4- oxadiazole-2-one
##STR67## dimethyldithiocarbamic acid 2-thiazolyl ester
##STR68## diethyldithiocarbamic acid 2-oxazolyl ester
##STR69## 2-propylmercaptopyridine
##STR70## 2-butylmercapto-1,3,4- thiadiazole
##STR71## 2-hexylmercaptopyrimidine
##STR72## dipropyldithiocarbamic acid 5-(1,2,4-thiadiazolyl)
ester
##STR73## dibutyldithiocarbamic acid 5-(1,2,4-oxadiazolyl)
ester
__________________________________________________________________________
Table 3
______________________________________
Sulfur compounds of formula (3)
R.sub.1 R.sub.2 Compound
______________________________________
CH.sub.3 CH.sub.3 tetramethylthiuram disulfide
C.sub.2 H.sub.5
C.sub.2 H.sub.5
tetraethylthiuram disulfide
C.sub.4 H.sub.9
C.sub.4 H.sub.9
tetrabutylthiuram disulfide
##STR74##
##STR75## tetrabenzylthiuram disulfide
##STR76##
C.sub.2 H.sub.5
bis(ethylphenylthiuram) disulfide
C.sub.6 H.sub.13
C.sub.6 H.sub.13
tetrahexylthiuram disulfide
C.sub.7 H.sub.15
C.sub.7 H.sub.15
tetraheptylthiuram disulfide
C.sub.8 H.sub.17
C.sub.8 H.sub.17
tetraoctylthiuram disulfide
C.sub.4 H.sub.9
C.sub.8 H.sub.17
bis(butyloctylthiuram)
disulfide
C.sub.2 H.sub.5
##STR77## bis(ethylbenzylthiuram) disulfide
CH.sub.3 C.sub.6 H.sub.13
bis(methylhexylthiuram)
disulfide
______________________________________
TABLE 4
______________________________________
Sulfur compounds of formula (4)
R.sub.3 Compound
______________________________________
CH.sub.3 bismethylxanthogen
C.sub.2 H.sub.5 bisethylxanthogen
C.sub.3 H.sub.7 bispropylxanthogen
C.sub.4 H.sub.9 bisbutylxanthogen
C.sub.5 H.sub.11 bispentylxanthogen
C.sub.6 H.sub.13 bishexylxanthogen
C.sub.7 H.sub.15 bisheptylxanthogen
C.sub.8 H.sub.17 bisoctylxanthogen
##STR78## bisbenzylxanthogen
______________________________________
Table 5
______________________________________
Sulfur compounds of formula (5)
R.sub.4 Compound
______________________________________
##STR79## dibenzoyl disulfide
##STR80## 4,4'-dinitrodibenzoyl disulfide
##STR81## 4,4'-dimethyldibenzoyl disulfide
##STR82## 4,4'-dichlorodibenzoyl disulfide
##STR83## 4,4'-dimethoxydibenzoyl disulfide
CH.sub.3 diacetyl disulfide
C.sub.2 H.sub.5
dipropionyl disulfide
C.sub.3 H.sub.7
dibutanoyl disulfide
C.sub.4 H.sub.9
dipentanoyl disulfide
C.sub.5 H.sub.11
dihexanoyl disulfide
C.sub.6 H.sub.13
diheptanoyl disulfide
C.sub.7 H.sub.15
dioctanoyl disulfide
C.sub.8 H.sub.17
dinonanoyl disulfide -
##STR84## di(phenylacetyl) disulfide
______________________________________
TABLE 6
______________________________________
Sulfur compounds of formula (6)
R.sub.5 R.sub.6 x Compound
______________________________________
CH.sub.2
CH.sub.2 1 thiodiglycolic acid
CH.sub.2
CH.sub.2 2 dithioglycolic acid
##STR85##
##STR86##
2 .alpha.,.alpha.'-dithiodipropionic acid
(CH.sub.2).sub.2
(CH.sub.2).sub.2
2 .beta.,.beta.'-dithiodipropionic acid
CH.sub.2
CH.sub.2 3 trithiodiglycolic acid
CH.sub.2
CH.sub.2 4 tetrathiodiglycolic acid
CH.sub.2
(CH.sub.2).sub.2
1 methylethylsulfide-.alpha.,.beta.'-
dicarboxylic acid
CH.sub.2
##STR87##
1 methylethylsulfide-.alpha.,.alpha.'- dicarbox
ylic acid
(CH.sub.2).sub.2
(CH.sub.2).sub.4
1 ethylbutylsulfide-.beta.,.delta.'-
dicarboxylic acid
(CH.sub.2 ).sub.8
(CH.sub.2).sub.8
1 dioctylsulfide-.theta.,.theta.'-
dicarboxylic acid
(CH.sub.2).sub.4
(CH.sub.2).sub.8
1 butyloctylsulfide-.delta.,.theta.'-
dicarboxylic acid
(CH.sub.2).sub.6
(CH.sub.2).sub.6
1 dihexylsulfide-.zeta.,.zeta.'-
dicarboxylic acid
______________________________________
The heat developable photosensitive composition containing an organic
silver salt according to the present invention may be prepared by using at
least one of sulfur compounds of formulas (1), (2), (3), (4), (5) and (6),
organic silver salt and halide. Usually, these components are dispersed in
an insulating medium by using an appropriate solvent and applied to a
substrate to form a heat developable photosensitive layer.
The heat developable photosensitive member may be formed, for example, in
such a manner that a reducing agent is mixed with a resin by means of an
appropriate solvent and coated onto the above-mentioned heat developable
photosensitive layer.
The substrate may be a metal plate such as aluminum, copper, zinc, silver
and the like, a metal laminate paper, a paper treated so as to prevent a
solvent from penetrating, a paper treated with a conductive polymer, and
plastics.
The silver halide or sulfur compound of formula (1), (2), (3), (4), (5) or
(6) may be incorporated to a layer containing the organic silver salt
(first layer), or coated on the layer in a form of the coating liquid
prepared by means of an appropriate solvent, or incorporated to a layer
adjacent to the layer. Further, the sulfur compound of formula (1), (2),
(3), (4), (5) or (6) may be incorporated upon producing the organic silver
salt, or added to a dispersion liquid of the organic silver salt, or
coated, together with a reducing agent, on the layer containing the
organic silver salt.
Representative organic silver salts used in the present invention are
aliphatic acid silver salts containing not less than 25 carbon atoms such
as silver behenate, silver arachidate, silver stearate, silver palmitate,
silver myristate, silver laurate, silver caprylate, silver
hydroxystearate, silver acetate, and silver butyrate, and other organic
silver compounds such as silver benzoate, silver
4-n-octadecyloxydiphenyl-4-carboxylate, silver-o-aminobenzoate, silver
acetoamidobenzoate, silver furoate, silver camphorate, silver
p-phenylbenzoate, silver phenyl acetate, silver salicylate, silver
terephthalate, silver phthalate, silver acid phthalate, silver
phthalazinone, silver benzotriazole, silver saccharine and the like.
For the purpose of imparting a photosensitivity to the organic silver
salts, a halide as shown below may be applied to form the silver halide:
various inorganic halides such as NH.sub.4 X, CrX.sub.2, IrX.sub.4,
InX.sub.4, CoX.sub.2, CdX.sub.2, KX, HX, SnX.sub.2, SnX.sub.4, SrX.sub.2,
SO.sub.2 X.sub.2, TiX.sub.3, TiX.sub.4, CuX.sub.2, NaX, PbX.sub.2,
NiX.sub.2, PdX.sub.2, MgX.sub.2, AlX.sub.3, ZnX.sub.2, MnX.sub.2,
BaX.sub.2, KAuX.sub.4, HAuX.sub.4, BiX.sub.3, CsX, FeX.sub.3, AgX,
HgX.sub.2, CaX.sub.2 and the like where X is chloro, bromo or iodo.
The amount of the halide may be optionally selected depending upon each
purpose. It is preferably not higher than 10% by weight based on the
organic silver salt, more preferably 10.sup.-3 -10% by weight.
If desired, dye sensitizers, toning agents, stabilizers and other additives
may be incorporated.
The developing procedure may be conducted by preliminarily incorporating a
reducing agent such as substituted phenols, substituted naphthols and the
like to the heat developable photosensitive layer or coating it on the
surface of the heat developable photosensitive layer and heat-developing.
Representative reducing agents are: hydroquinone, methyl hydroquinone,
chlorohydroquinone, bromohydroquinone, catechol, pyrogallol,
methylhydroxynaphthalene, aminophenol,
2,2'-methylene-bis-(6-t-butyl-4-methylphenol),
4,4'-butylidene-bis-(6-t-butyl-3-methylphenol),
4,4'-bis-(6-t-butyl-3-methylphenol), 4,4'-thio-bis-(6-t-2-methylphenol),
octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate,
2,6-di-t-butyl-p-cresol, 2,2'-methylene-bis-(4-ethyl-6-t-butylphenol),
phenidone, metol, 2,2'-dihydroxy-1,1'-binaphthyl,
6,6'-dibromo-2,2'-dihydroxy-1,1'-binaphthyl,
6,6'-dinitro-2,2'-dihydroxy-1,1'-binaphthyl,
bis-(2-hydroxy-1-naphthyl)methane and mixtures thereof.
For example, these reducing agents may be mixed with a resin such as
cellulose acetate by using an optional solvent and applied to a surface of
the layer containing the organic silver salt to form a layer containing
the reducing agent (second layer).
It is also possible to carry out a developing procedure without
incorporating a developing agent (a reducing agent) to the heat
developable photosensitive member, that is, it is possible to effect an
external type of wet developing procedure. For example, a developing
solution containing a reducing agent as mentioned above is applied to a
buffer solution adjusted to a low pH. Fixing may be effected with a usual
solution of sodium thiosulfate.
As the solvents for dispersing the organic silver salt in an insulating
medium, there may be mentioned methylene chloride, chloroform,
dichloroethane, 1,1,2-trichloroethane, trichloroethylene,
tetrachloroethane, carbon tetrachloride, 1,2-dichloropropane,
1,1,1-trichloroethane, tetrachloroethylene, ethyl acetate, butyl acetate,
isoamyl acetate, cellosolve acetate, toluene xylene, acetone, methyl ethyl
ketone, dioxane, tetrahydrofuran, dimethylamide, N-methyl-pyrrolidone,
alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl
alcohol and the like, and water.
As the insulating medium used in the present invention, the
electrically-insulating materials may be used. For example, there may be
mentioned polystyrene resin, polyvinyl chloride resin, phenolic resin,
polyvinyl acetate resin, polyvinyl acetal resin, epoxy resin, xylene
resin, alkyd resin, polycarbonate resin, poly(methyl-methacrylate) resin,
polyvinyl butyral resin, gelatine resin, polyester, polyurethane, acetyl
cellulose, synthetic rubber, polybutene, and the like.
If desired, there may be added a plasticizer. As the plasticizer, there may
be mentioned dioctyl phthalate, tricresyl phosphate, diphenyl chloride,
methyl naphthalene, p-terphenyl, diphenyl and the like.
The amount of the insulating medium upon forming the photosensitive layer
is usually 0.02-20 parts by weight, preferred with 0.1-5 parts by weight,
per one part by weight of the organic silver salt compound.
The total thickness of the first layer containing the silver salt and the
second layer containing the reducing agent may be optionally determined in
view of the purpose, use and durability, and it may be usually in the
range of from 1 micron to 50 microns, more preferably from 2 microns to 30
microns.
The invention will be understood more readily by reference to the following
examples. However, these examples are intended to illustrate the invention
and are not to be construed to limit the scope of the invention.
EXAMPLE 1
In a ball mill, 10 g. of silver behenate, 150 g. of methyl ethyl ketone,
150 g. of toluene and 15 g. of silica powder (Syloid #244, a trade name
for a product of Fuji Davison Chemical Ltd.) were mixed, pulverized and
dispersed for 72 hours. Then, 9 g. of polyvinyl butyral resin (S-Lec BM-1,
a trade name for a product of Sekisui Kagaku K.K.) was added to the
resulting dispersed mixture and further ball-milled for 15 minutes. 20 mg.
of 2-mercaptobenzoxazole (the sulfur compound) in 10 ml. of acetone was
added thereto and sufficiently uniformly mixed to prepare a first
composition. The resulting mixture was coated onto a two-sided art paper
of 100 microns in thickness with a coating rod so as to be 8 microns in
thickness after drying.
In 19 g. of acetone were mixed and dissolved 1 g. of
2,6-di-t-butyl-p-cresol, 0.5 g. of 1-phthalazone, 1 g. of acetyl cellulose
(Daicel L-30, a trade name for a product of Daicel Ltd.) and 5 mg. of
ammonium bromide, and the resulting solution (second composition) was
coated onto the silver behenate-containing layer formed in the foregoing
at a dark place in a thickness of 4 microns after drying to prepare a heat
developable photosensitive member, Sample-A.
On the other hand, Sample-B for comparison was prepared in the same manner
as that mentioned above except that no 2-mercaptobenzoxazole was used in
forming the silver behenate-containing layer.
The above-mentioned Samples-A and B were exposed to a tungsten light source
(1500 lux) and heat-developed by using a roller type heat developing
apparatus to form visualized images. The density of the images was
measured by means of a densitometer (supplied by Nalumi Ltd.) to make a
comparison with respect to various characteristics of the samples. The
results are shown in the following table.
______________________________________
I. Relative Sensitivity etc.
(Exposure time: 20 sec., Heat development for
3 sec. at 120.degree. C.)
Sample-A Sample-B
______________________________________
(a) Relative Sensitivity
16 1
(b) Maximum Density (D.sub.max)
1.3 0.5
(c) Fog Density (D.sub.min)
0.2 0.1
(d) Shelf-life* 200 days 30 days
______________________________________
II. Development Latitude (Exposure time: 10 sec.)
Developing time Sample-A Sample-B
(at 120.degree. C.)
D.sub.max
D.sub.min
D.sub.max
D.sub.min
______________________________________
1 sec. 0.2 0.1 0.1 0.1
2 sec. 0.6 0.1 0.2 0.1
3 sec. 1.1 0.2 0.5 0.1
4 sec. 1.2 0.2 0.6 0.4
5 sec. 1.3 0.2 0.6 0.5
______________________________________
Developing Temperature
(Developing time Sample-A Sample-B
of 3 sec.) D.sub.max
D.sub.min
D.sub.max
D.sub.min
______________________________________
100.degree. C. 0.5 0.1 0.1 0.1
110.degree. C. 0.7 0.1 0.2 0.1
120.degree. C. 1.1 0.2 0.5 0.1
130.degree. C. 1.3 0.3 0.6 0.4
150.degree. C. 1.4 0.8 0.6 0.6
______________________________________
*Period of time required for reduction of sensitivity by half.
In the above table, the relative sensitivities were obtained in such a
manner that the Samples were exposed through a grey scale and subjected to
heat development and then the density of the obtained images was measured
by a densitometer (supplied by Nalumi Ltd.) to calculate the relative
sensitivities from the relation between the exposure amount and the
density. The maximum density represents the density of the image obtained
by exposing the samples to the above-mentioned light source for a
predetermined time without the use of a grey scale followed by the
development. The fog density represents the density of the unexposed
portion after the heat-development. The shelf-life is the period of time
required for reduction of the sensitivity by half.
EXAMPLE 2
Photosensitive members were prepared in the same procedure as that in
Example 1 except that various compounds of the general formulas (1), (2)
and (6) were used as the sulfur compound, and the wavelength edge of the
photosensitivity range and relative sensitivities were measured, the
results of which are shown in the following table. In this connection, the
photosensitive member having the layer containing
4-chloro-2-benzylmercaptopyrimidine was selected as the standard for
evaluating the sensitivity, that is, 1. In addition, the measurement of
the wavelength edge of the photosensitivity range was conducted by a
grating spectrograph (RM-23-1, a trade name for a product of Nalumi Ltd.)
provided with a xenon light source. The other measurement was conducted in
the same manner as that in Example 1.
______________________________________
Wavelength
edge of
photo-
sensitivity
Relative
Sulfur Compound range (nm) Sensitivity
______________________________________
None 470 0.06
______________________________________
1. Sulfur compound of the general formula (1):
2-mercaptobenzothiazole
510 1.1
2-(2,4-dinitrophenylmercapto)
benzothiazole 530 1.2
2-mercaptobenzimidazole
500 0.9
2-mercaptobenzoxazole
510 1.0
______________________________________
2. Sulfur compound of the general formula (2):
2-mercaptothiazoline
490 0.5
2-mercaptoimidazole 500 0.8
2-methylmercapto-4,5-
diphenylimidazole 510 0.4
2-methylmercaptoimidazoline
490 0.8
*4-chloro-2-benzylmercapto-
pyrimidine 500 1.0
6-(2,4-dinitrophenylmercapto)-
4-methyl-2-pyrimidone
510 1.1
3-phenyl-5-mercapto-1,2,4-
thiodiazole 500 0.8
diethyldithiocarbamic acid
2-oxazolyl ester 520 1.2
______________________________________
3. Sulfur compound of the general formula (6):
dithioglycolic acid 490 0.4
.beta.,.beta.'-dithiodipropionic acid
490 0.5
tetrathiodiglycolic acid
510 0.07
______________________________________
*Standard
EXAMPLE 3
A heat developable photosensitive member was prepared in the same manner as
that in Example 1 except that 17 g. of an equimolar mixture of silver
behenate and behenic acid was used in place of 10 g. of the silver
behenate. When the photosensitive member thus prepared was exposed under
the same condition as that in Example 1, a developing time of 6 seconds
(at 120.degree. C.) was required to obtain the maximum density (1.3) of
the image which was obtained by the heat development at 120.degree. C. for
3 seconds in Example 1. On the other hand, the fog density was 0.15 or
less so that the development latitude was found to be improved.
EXAMPLE 4
To the second composition used in Example 1 containing
2,6-di-t-butyl-p-cresol was added 5 mg. of a dye sensitizer of the
formula:
##STR88##
The same procedure as that for preparing Sample-A was repeated except that
the above-mentioned composition was used in place of the second
composition to prepare Sample-C.
The characteristics of Sample-C were measured in the same manner as that in
Example 1 to obtain the results shown in the following table.
______________________________________
Sample-A Sample-C
______________________________________
Relative Sensitivity
1 3.0
Maximum Density
1.3 1.3
Fog Density 0.2 0.3
Wavelength edge of
photosensitivity
range 510 nm 650 nm
______________________________________
(Exposure time: 20 sec., Heat development for 3 sec. at 120.degree. C.)
EXAMPLE 5
In a ball mill, 10 g. of silver behenate, 75 g. of methyl ethyl ketone and
75 g. of toluene were mixed, pulverized and dispersed for 72 hours. T | | |
