Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2002-11-26
2004-12-07
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S599000, C430S605000, C430S264000, C430S570000, C430S581000, C430S582000, C430S583000, C430S584000, C430S585000
Reexamination Certificate
active
06828088
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a silver halide photographic light-sensitive material. In particular, the present invention relates to an ultrahigh contrast negative type photographic light-sensitive material suitable as a silver halide photographic light-sensitive material used for a photomechanical process.
RELATED ART
In photomechanical processes used in the field of graphic arts, used is a method in which photographic images of continuous tone are converted into so-called dot images in which variable image density is represented by sizes of dot areas, and such images are combined with photographed images of characters or line originals to produce printing plates. For silver halide photographic light-sensitive materials used for such a purpose, ultrahigh contrast photographic characteristic enabling clear distinction between image portions and non-image portions has been required in order to obtain favorable reproducibility of characters, line originals and dot images.
As a system responding to such a requirement, there has been known the so-called lithographic development method in which a silver halide light-sensitive material comprising silver chlorobromide is processed with a hydroquinone developer having an extremely low effective concentration of sulfite ions to form images of high contrast. However, in this method, the developer is extremely unstable against oxidation by air since the sulfite ion concentration in the developer is extremely low, and therefore a lot of developer must be replenished in order to stably maintain the developer activity.
As image forming systems in which the instability of the image formation according to the lithographic development method is eliminated and light-sensitive materials are processed with a developer showing good storage stability to obtain ultrahigh contrast photographic characteristic, there can be mentioned those described in U.S. Pat. Nos. 4,166,742, 4,168,977, 4,221,857, 4,224,401, 4,243,739, 4,269,922, 4,272,606, 4,311,781, 4,332,878, 4,618,574, 4,634,661, 4,681,836, 5,650,746 and so forth. These are systems in which a silver halide photographic light-sensitive material of surface latent image type containing a hydrazine derivative is processed with a developer containing hydropuinone/metol or hydroquinone/phenidone as main developing agents and 0.15 mol/l or more of sulfite preservative and having pH of 11.0-12.3 to form ultrahigh contrast negative images having a gamma of 10 or higher. According to these systems, photographic characteristics of ultrahigh contrast and high sensitivity can be obtained, and because sulfite can be added to the developer at a high concentration, stability of the developer to air oxidation is markedly improved compared with conventional lithographic developers.
In order to form sufficiently ultrahigh contrast images with use of a hydrazine derivative, it is necessary to perform processing with a developer having pH of 11 or higher, usually 11.5 or higher. Although it becomes possible to increase the stability of the developer by use of a sulfite preservative at a high concentration, it is necessary to use such a developer of high pH as described above in order to obtain ultrahigh contrast photographic images, and the developer is still likely to suffer from air oxidation and instable even with the presence of the preservative. Therefore, various attempts have been made in order to realize ultrahigh images with a lower pH to further improve stability of the developer.
For example, U.S. Pat. No. 4,269,929 (Japanese Patent Laid-open Publication (Kokai, henceforth referred to as “JP-A”) No. 61-267759), U.S. Pat. No. 4,737,452 (JP-A-60-179734), U.S. Pat. Nos. 5,104,769, 4,798,780, JP-A-1-179939, JP-A-1-179940, U.S. Pat. Nos. 4,998,604, 4,994,365 and JP-A-8-272023 disclose methods of using a highly active hydrazine derivative and a nucleation accelerator in order to obtain ultrahigh images by using a developer having pH of less than 11.0.
However, silver halide photographic light-sensitive materials used for such image-forming systems have problems concerning processing stability, for example, due to exhaustion of processing solutions, activities of hydrazine compound and nucleation accelerator vary and thus sensitivity fluctuates. As means for improving processing stability, use of an emulsion providing a higher contrast can be mentioned. However, it causes a problem that use of an emulsion providing a higher contrast causes reduction of sensitivity. Therefore, it has been desired to develop a technique for obtaining higher sensitivity with superior processing stability.
Considering these problems of the conventional techniques, an object of the present invention is to provide a silver halide photographic light-sensitive material that provides high contrast and high sensitivity.
SUMMARY OF THE INVENTION
As a result of various researches of the inventors of the present invention, they found that a superior silver halide photographic light-sensitive material could provided by using a particular silver halide emulsion to provide a gamma exceeding a certain level, and thus accomplished the present invention.
That is, the present invention provides a silver halide photographic light-sensitive material comprising at least one silver halide emulsion layer on a support, wherein 40 mol % or more, preferably 45-75 mol % of silver halide contained in the silver halide emulsion layer is silver bromide and the silver halide contains 1×10
−6
mole or more, preferably 5×10
−6
mole to 5×10
−3
mole per mole of silver of a metal complex containing one or more cyanide ligands, and the silver halide photographic light-sensitive material has a characteristic curve drawn in orthogonal coordinates of logarithm of light exposure (x-axis) and optical density (y-axis) using equal unit lengths for the both axes, on which gamma is 4.0 or more for the optical density range of 0.1-1.5.
In the silver halide photographic light-sensitive material of the present invention, the metal complex containing one or more cyanide ligands exists in the inside of silver halide crystals, and preferably 99 mol % or less, more preferably 95 mol % or less, of the total amount of silver contained in the silver halide crystals is contained in the inside of the crystals. Further, the silver halide crystals preferably have an aspect ratio (diameter as circle/thickness) of 2 or less.
At least one of silver halide emulsion layers constituting the silver halide photographic light-sensitive material of the present invention preferably contains at least one spectral sensitization dye represented by the following formula (I), (II), (III), (IV), (V), (VIa) or (VIb).
In the formula, Y
11
, Y
12
, Y
13
and Y
14
each independently represent ═N(R
1
), an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom, provided that either one of Y
13
and Y
14
is ═N(R
1
), and Y
11
, Y
12
and Y
13
or Y
11
, Y
12
and Y
14
do not simultaneously represent a sulfur atom. R
11
represents an aliphatic group having a water-solubilizable group and 8 or less carbon atoms, and R
1
, R
12
and R
13
each independently represent an aliphatic group, an aryl group or a heterocyclic group. However, at least two of R
1
, R
12
and R
13
have a water-solubilizable group. Z
11
represents a nonmetallic atom group required to form a 5- or 6-membered nitrogen-containing heterocyclic ring, and the 5- or 6-membered nitrogen-containing heterocyclic ring formed with Z
11
may have a condensed ring. W
1
represents an oxygen atom, a sulfur atom, ═N(R
1
) or ═C(E
11
)(E
12
). E
11
and E
12
each independently represent an electron-withdrawing group. These may bond to each other to form a keto ring or an acidic heterocyclic ring. L
11
and L
12
each independently represent a substituted or unsubstituted methine group, and l
11
represents 0 or 1. M
1
represents an ion required to offset the charge of the molecule. n
11
represents a number required to neutralize the total charge of the molecule. How
Fuji Photo Film Co. , Ltd.
Letscher Geraldine
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