The present invention relates to a silver halide photographic light-sensitive material, and a method for forming an ultra-high-contrast image, using the same, and particularly to an ultra-high-contrast silver halide photographic light-sensitive material used in the field of graphic arts, and a photographic image-forming method using the same.
In order to make reproduction of a line original or a continuous tone original by halftone dots, better in the field of graphic arts, an image-forming system exhibiting a photographic property of ultra-high-contrast (particularly, xcex3=10 or more) is necessary.
As a method for obtaining a high-contrast photographic property, a lithographic development manner using the so-called xe2x80x9cinfectious development effectxe2x80x9d has been hitherto used. This manner has the drawback that the developing solution used for it is unstable and thus is difficult to use. An image-forming system, in which development is performed with a developing solution having good storage stability, to obtain an ultra-high-contrast photographic property, has been desired. Examples thereof are disclosed 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 the like. These relate to a system of developing a surface-latent-image-type silver halide photographic light-sensitive material, to which a hydrazine derivative is added, with a stable MQ (Metol-and-Quinol-containing) or PQ (1-phenyl-pyrazolidone-and-hydroquinone-containing) developing solution having a pH of 11.0 to 12.3, to obtain an ultra-high-contrast negative image whose xcex3 is over 10. According to this system, photographic properties of ultra-high-contrast and high sensitivity can be obtained, and a sulfite salt having a high concentration can be added to the developing solution. Therefore, stability of the developing solution against air oxidization is highly improved compared with any conventional lithographic developing solution.
In the field of photoengraving, a photographic light-sensitive material having good reproducibility of an original, a stable processing solution, easy replenishment, and the like, are desired, to cope with variation and complication of printed matters.
An original, particularly in the step of photographing an original comprising line images, is made by combining typeset characters, handwritten characters, illustrations, a photograph converted to halftone dots, and the like. In one original, therefore, image portions having different densities and line widths coexist being intermixed. A process camera, a photographic light-sensitive material, or an image-forming method for finishing such an original with high reproducibility, are intensely desired. In the plate-making of a catalogue or a large-sized poster, enlarging or scaling down of a dot photograph is widely carried out. In plate-making in which dots are enlarged, lines are made large, to give images in which dots fade. In plate-making in which dots are scaled down, the number of lines per inch becomes larger than that of an original, to give images in which dots are very fine. Accordingly, in order to keep halftone dot reproducibility good, an image-forming method that can give wider latitude is desired.
To improve reproduction of the original, JP-A-3-39952 (the term xe2x80x9cJP-A-xe2x80x9d as used herein means an unexamined published Japanese patent application), JP-A-3-174143, or the like disclose an ultra-high contrast silver halide light-sensitive material having a multilayer structure, which includes a layer containing a redox compound that releases a development inhibitor by oxidation, and a light-sensitive silver halide emulsion layer containing a hydrazine derivative. In this method, reproduction of an original is remarkably improved.
However, the improving of original-reproducibility is an eternal theme for graphic art light-sensitive materials. Thus, a system giving a better original-reproducibility is intensely desired.
The above method, in which a surface-latent-image-type silver halide photographic light-sensitive material, to which a hydrazine derivative is added, is processed in a developer having a pH of 11.0 to 12.3, makes it possible to improve the stability of a developer by using a high-density sulfurous acid preservative. However, in order to obtain an ultra-high contrast photographic image, it is necessary to use a developer having a relatively high pH value. In this case, the developer tends to be oxidized by air, and it is therefore necessary to replenish a large amount of a developer. In view of this, various ideas, in which an ultra-high contrast photographic image-forming system utilizing nuclei formation developing of a hydrazine compound is realized using a developer having a lower pH, have been attempted.
In order to obtain an ultra-high contrast image by using a stable developer having a pH of lower than 11.0, a method using a highly active hydrazine-type nucleating agent, and a nucleation accelerator, is disclosed in U.S. Pat. No. 4,269,929 (JP-A-61-267759), U.S. Pat. No. 4,737,452 (JP-A-60-179734), U.S. Pat. Nos. 5,104,769, and 4,798,780; JP-A-1-179939 and JP-A-1-179940; U.S. Pat. Nos. 4,998,604 and 4,994,365, and JP-A-8-272023.
However, the above method cannot be said to be satisfactory in the point of original-reproducibility in the case of using the aforementioned redox compound that releases a development inhibitor by oxidation. There is a strong need to develop light-sensitive materials having higher original-reproducibility. Also, in view of environmental problems, which have been greatly emphasized in recent years, there is a strong need to develop light-sensitive materials that cause less fluctuation in the photographic properties, and that also cause less fluctuation in original-reproducibility, with change in the composition of a developer, to decrease developer waste.
On the other hand, Japanese Patent No. 2,676,439 discloses a hydrazine-type redox compound containing a sulfo group, and JP-A-9-269553 discloses a hydrazine-type redox compound having in its molecule two sulfonamido groups, and a redox compound having phenol as its moiety. However, these compounds make it impossible to give a silver halide photographic light-sensitive material having good original-reproducibility, and suppressed black-spots (black peppers), high sensitivity, and high contrast, by use of a developing solution having a low pH.
The present invention is a silver halide photographic light-sensitive material, which comprises at least one compound represented by the following formula (1): 
wherein PUG represents a nitrogen-containing heterocyclic group which is bonded to the adjacent carbonyl group through a nitrogen atom, the heterocyclic group is a heterocyclic group which directly or indirectly has at least nitro group as its substituent(s) and can give a pKa value of 9 to 11, ph represents a phenyl group and directly or indirectly has at least one dissociating group as its substituent(s), Z represents a substituent which is capable of substitution on the benzene ring, and p is an integer of 0 to 4.
Further, the present invention is a method of processing a silver halide photographic light-sensitive material, which comprises the step of developing the silver halide photographic light-sensitive material described above with a developing solution having a pH of 9.0-11.0 after imagewise exposure to light.
Other and further features and advantages of the invention will appear more fully from the following description.