JPH03615B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a silver halide photographic material, and more particularly to a silver halide photographic emulsion suitable for a light-sensitive material for bright room use. In recent years, in the printing field, the complexity of printed matter,
Due to the development of scanners, there is a demand for improved efficiency in the return process. Therefore, compared to the conventionally used return film, it is 10 ^-3 ~
A photographic film with ultra-low sensitivity of about 10 ^-5 was developed,
It has begun to be put into practical use as a return film that can be handled in a bright room (under a white light without ultraviolet light), that is, as a light-sensitive material for bright rooms. The performance required of such a light-sensitive material for use in a bright room is that it has a sufficient maximum density with high contrast, can be handled for a long time in a bright room, and has high sensitivity to ultraviolet light sources. This is the case. However, it cannot be said that conventional photosensitive materials for use in bright rooms fully satisfy the above-mentioned performance, and there is a desire to develop improved photosensitive materials for use in bright rooms. As a silver halide emulsion for light-sensitive materials for bright room use,
A method of using a large amount of rhodium as an inorganic desensitizer in silver halide containing silver chloride as described in JP-A-56-125734, or a method generally used in direct positive silver halide emulsions. It is manufactured by a method using an organic desensitizer such as pinacryptol yellow. However, the present inventors have found that emulsions produced by any of the above methods have a serious drawback in that they can only guarantee insufficient safety when handled as photosensitive materials for bright rooms under bright white light. I confirmed that there is. Emulsions using rhodium salts cause significant fogging under bright room light. Emulsions using organic desensitizers can be handled under bright room light for long periods of time without causing fogging like rhodium salts do, but the Even if left under room light for a short period of time, a significant decrease in sensitivity occurred. Of course, it is sufficient to develop the image immediately after exposure, but for reasons such as staleness, it is sometimes placed under bright room light after image exposure, and it is desired that the handling safety in this case be improved. ing. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a bright room film that can be safely handled for a long time under white light from which ultraviolet rays are removed. That is, the object of the present invention is to provide a bright room film that does not cause fogging under white light and does not exhibit sensitization or desensitization even when placed under white light after image exposure. Other objects of the invention will be apparent from the following description. As a result of extensive research in order to achieve the above object, the present inventors have discovered that an organic desensitizer and a polycarboxylic acid represented by formula (1) are added to a negative-working fine-grain silver halide emulsion containing at least 80 mol% of silver chloride. It has been found that the above object can be achieved by an emulsion containing at least one of the following. A(-COOM) _o () (A=organic acid residue, M=hydrogen ion, metal ion n=an integer of 2 or more) Representative examples of these compounds are shown below.

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[Formula] The above compounds greatly improve safety under white light, especially (2) citraconic acid, (7) malic acid,
(8) itaconic acid, (9) succinic acid, and (12) citric acid are good.
In other words, it is preferable that the carboxylic acid has two carbon atoms between the carbon atoms. It is completely unknown that such polycarboxylic acids are useful for bright room films, and the mechanism is not completely understood, so it is a unique phenomenon. Moreover, monocarboxylic acids have almost no effect. These polycarboxylic acids are preferably added to the silver halide emulsion, but they may also be added to a layer adjacent to the emulsion layer and diffused into the emulsion layer. The addition time may be at any time during the emulsion manufacturing process, and the amount added can generally be appropriately selected within the range of 10 ^-4 mol to 1 mol per mol of silver halide. The organic desensitizer used in the present invention is generally known to be used in direct positive silver halide emulsions. That is, the organic desensitizer used in the present invention is characterized by its polarographic half-wave potential, that is, its redox potential determined by polarography. Organic desensitizers useful in the present invention are those in which the sum of polarographic anodic potential and cathodic potential is positive. Methods for measuring these redox potentials are described, for example, in US Pat. No. 3,501,307. Specific examples of such organic desensitizers are described in numerous patent specifications, all of which have the same effect in the present invention. 39-20261, 1973-26751, 1973-13167, 1972-8833, 1974-8746, 10197-1970, 1972-37530, JP-A-1989-24734, 1973 −84639, 1984−
142525, U.S. Patent No. 2271229, U.S. Patent No. 2541472,
Same No. 3035917, Same No. 3062651, Same No. 3124458,
Compounds described in specifications such as No. 3326687 and No. 3671254 can be used. The silver halide emulsion used in the present invention is a negative emulsion containing at least 80 mole percent silver chloride. A negative emulsion is a normal type of silver halide emulsion that forms a negative image on a positive raw material, which is distinguished from a direct positive silver halide emulsion. Preferably
A silver halide emulsion containing 90 mol% or more of silver chloride. It is preferable that silver iodide is not substantially contained, but a very small amount, for example, about 0.5 mol %, can be contained if necessary. The silver halide emulsion used in the present invention is fine-grained silver halide, preferably with an average grain size of 0.05 to 0.3μ.
It is of a certain degree. Further, it is preferable that 90% or more of the total number of particles have a particle size within ±10% of the average particle size. The method for preparing silver halide emulsions is: forward mixing,
Any known method such as back mixing or simultaneous mixing may be used. The silver halide emulsion obtained by the present invention can be used in general photographic emulsions such as stabilizers, covering power improvers, anti-irradiation agents, film property improvers, surfactants, hardeners, matting agents, developing agents, etc. It can contain additives and is coated on a known support. It may have other hydrophilic colloid layers such as a protective layer and an undercoat layer. The light-sensitive material for bright room use obtained by the present invention is a light source rich in ultraviolet light mainly used in the printing field.
For example, exposure is performed using a mercury lamp, an ultra-high pressure mercury lamp, a metal halide, or the like. The photosensitive material for bright room use obtained according to the present invention can be safely handled for a long time under white light even before and after the above-mentioned exposure. Example 1 Silver halide was precipitated in a conventional manner using 100 mg of adenine and 10 ^-5 moles of rhodium chloride per mole of silver chlorobromide containing 95 mol% of silver chloride, and physical ripening was performed to obtain an average grain. An emulsion with a diameter of 0.2 μm and a narrow particle size distribution was obtained. After desalting and redissolving this emulsion, 500 mg of pinacryptol yellow was added per mole of silver halide as an organic desensitizer, and a hardening agent,
A surfactant was added, and the mixture was coated on a polyester film at a silver concentration of 3.5 g/m ² together with a gelatin solution for a protective layer, and dried (blank sample). Next, 0.01 mole of the polycarboxylic acid shown in Table 1 per mole of silver halide was added to the above emulsion, and the mixture was coated under the same conditions as the blank sample. Two copies of each of these samples were exposed using a bright room printer through film with a density difference. One sheet was processed under a yellow safelight, and the other sheet was placed under a 500 Lux ultraviolet-free fluorescent light for 30 minutes before being processed. Development was performed at 35° C. for 23 seconds using a developer containing phenidone and hydroquinone, followed by fixation and drying. The sensitivity of the sample not exposed to white fluorescent light is set to 100,
The sensitivity of the sample was determined after exposure to a white fluorescent lamp for 30 minutes and was used as a guideline for handling in a bright room. In other words, it can be said that the higher the sensitivity after exposure under a white fluorescent lamp is 100 or less, the better it is. These results are shown in Table 1.

Table 1 As Table 1 shows, the polycarboxylic acids of the present invention significantly improve handling under white light. Example 2 Various organic desensitizers were tested. The emulsion preparation method was the same as in Example 1, and the organic desensitizer was added in an appropriate amount of 100 to 500 mg per mole of silver halide. A test was carried out by applying itaconic acid as a representative polycarboxylic acid in the same manner as in Example 1, adding 0.2 mol per mol of silver halide. Note that the sensitivity of the sample to which itaconic acid was not added was set to 100 for convenience.

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[Table] (A is without itaconic acid added, B is with itaconic acid added)
Sensitivity after irradiation with 500 lux white fluorescent light for 30 minutes,
At this time, set the sensitivity of the white fluorescent light to 100 without irradiation.
And so. ) All of the organic desensitizers listed in the table have a positive sum of polarographic redox potentials; if one with a negative sum of redox potentials (for example, 1,1'-diethylquinocyanine) is used, it will emit white fluorescence. Irradiation with light caused a large amount of fog. Therefore, organic desensitizers having a positive sum of polarographic redox potentials are important for bright room films.

Claims (1)

[Scope of Claims] 1. A negative-working fine-grain silver halide photographic emulsion containing at least 80 mol % of silver chloride, an organic desensitizer whose sum of polarographic anode potential and cathode potential is positive, and a polycarbonate represented by the following formula. A silver halide photographic emulsion containing at least one type of acid. A(-COOM) _o (A=organic acid residue, M=hydrogen ion or metal ion n=an integer of 2 or more).