JPS6126040A - Silver halide photographic emulsion - Google Patents

Abstract

PURPOSE:To enhance contrast and max. density, to remarkably sensitize a silver halide emulsion, and to prevent fog in the light and defects of desensitization by incorporating a specified amt. of silver chloride and a desensitizing agent. CONSTITUTION:A negative emulsion, such as silver chloride, chlorobromide, chloroiodide, or chlorobromoiodide, contg. at least 70mol%, preferably, 80mol% silver chloride is used as an emulsion, and its average grain diameter is, e.g., 100-400nm. At least 90% of the number of the total grains are, preferably, contained in the range of + or -10% of the average grain diameter. The desensitizer to be added in this emulsion is organic and positive in the sum of both the anode and cathode potentials of a polarograph, and it is added in an amt. not exceeding the inherent sensitivity of the emulsion logE=1.3, and in the case of a silver chloride emulsion, logE=1.0, and an amt. necessary for decreasing sensitivity. As a result, since the obtained emulsion is high in sensitivity, exposure time can be shortened or illuminance can be lowered, thus permitting rationalization, such as saving of power and shortening of operation length of time.

Description

DETAILED DESCRIPTION OF THE INVENTION (4) Industrial Application Field The present invention relates to a silver halide photographic emulsion, and more particularly to a silver halide photographic emulsion used in a high-sensitivity light-sensitive material.

(In recent years, in the printing field, due to the complexity of printed matter and the development of scanners, there has been a need to improve the efficiency of the return process compared to the conventional return film used for this purpose.) A photographic film with an ultra-low sensitivity of about 10 to 10-5 was developed, and it has begun to be put into practical use as a film that can be handled in a bright room (white fluorescent film that excludes ultraviolet rays), that is, as a photosensitive material for bright rooms. The performance required for such bright room photosensitive materials is that it has high contrast and sufficient maximum density, can be handled for long periods of time in a bright room, and has high sensitivity to printer light sources. However, it cannot be said that the conventional photosensitive materials for bright room use fully satisfy the above-mentioned performance.

Generally, emulsions with ultra-low sensitivity that can be used as photosensitive materials for bright rooms can be obtained by using inorganic desensitizers such as rhodium salts or organic desensitizers such as pinacryptol yellow.

For example, methods for manufacturing photosensitive materials for bright room use using a large amount of rhodium salts include 125734/1986, 149030/1983, 149031/1973,
8-190943 etc., and the sensitivity of the emulsion is about 1/i00 to about 1 in a silver halide emulsion mainly composed of silver chloride.
◇ However, silver chloride emulsions that use rhodium salts to reduce sensitivity tend to produce capri when handled under bright room light, and this is especially noticeable as the sensitivity is increased. It has the disadvantage of causing a significant increase in capri.

On the other hand, the applicant has produced a silver halide emulsion using an organic desensitizer that has almost the same sensitivity as the above-mentioned super-low sensitivity silver halide emulsion mainly composed of silver chloride produced using a rhodium salt. It has been confirmed that by doing so, a light-sensitive material for bright room use without the disadvantages of rhodium salts can be obtained.However, silver halide emulsions produced using organic desensitizers are mainly composed of silver chloride. Therefore, while it is easy to obtain a high maximum density with high contrast, there is a new problem in that if the image is left under bright room light after image exposure until development, a significant decrease in sensitivity will occur. was discovered, and various methods were proposed to solve this new problem (for example, patent application 1982-
31413, Kaikai 58-33600, Showa 58-545
36, No. 59-39413, etc.) However, it cannot be said that it is a complete method that can stably solve the problem. Solving the above-mentioned problems with silver halide emulsions for light-sensitive materials for bright room use, the halogenated emulsion achieves high contrast, high maximum density, and dramatic sensitization, and does not cause capri or desensitization under bright room light. An object of the present invention is to provide a silver photographic emulsion.

(B) Structure of the Invention The present invention provides a negative-working fine-grain silver halide photographic emulsion containing at least 70 mol% of silver chloride and a desensitizer, wherein the desensitizer is the sum of the anode potential and the cathode potential of a polarograph. is a positive organic desensitizer, and the amount of the organic desensitizer reduces the sensitivity of the emulsion to ogn=1.3 (however, in the case of silver chloride)
OgB=1. The present invention will be further described in detail below. , which is generally known to be used in direct positive silver halide emulsions; that is, the organic desensitizer used in the present invention has a polarographic half-wave potential part, and its redox potential determined by polarography. Characterized by electric potential.

Organic desensitizers useful in the present invention include those in which the sum of polarographic anodic potential and polarographic depolarization potential is positive.

These redox potential measurement methods are described, for example, in US Pat. No. 3,501,307.

Specific examples of such organic desensitizers are described in numerous patent specifications and documents, all of which have the same effect in the present invention. Open 39-20261, 1972
-26751. Showa 43-13167, Kaikai 45-88
83, Opening number 47-8746, Opening number 47-10197, Opening number 50-37530, Opening number 48-24734, Opening number 4
9-84639, opening 5s-x42szst U.S. Patent No. g271,229, U.S. Pat. No. 458, No. 3,326,687,
Compounds described in specifications such as No. 3,671,254 can be used.

An example is shown below.

(D-1) 1.3-diethyl-I+-methyl-2+
-phenylimidazo[4,5-b:l-quinoxazino-
3T-indolocarbocyanine-iodide (D-2) Pinacryptol Yellow (D-3)
1,1. '3, 3, 3. +3-hexamethyl-5,
5I-dinitroindocarbocyanine P-)luenesulfonate (D-4) 5.51-dichloro-3,3
I-diethyl 6,6-sinitrothiacarbocyanine iodide (D-5), 1,1'-dimethyl-2,2-diphenyl-3,3'-indolocarbocyanine bromide (D-6) 1 .1. '3.3-Tetraethylimidazo(4,5-b) quinoxalinocarbocyanine chloride (D-7) 5---Nitrobenzylidenerhodanine (D-8) 6-/Roro 4-nitronitrobenzotriazole (D-9) 1. IL-diptyl-4,4?
- Dibromide (D-10) 1,1' in bipyridinium
-ethylene-2,2'nibipyridinium diglomide (D 11) 4-(P-n-amyloxif X==
)-2,6-di(p-ethylphenyl)thiapyrylium verchlorate (D-12) 2-mercapto-4-methyl-5-nitrothiazole (D-13) 2-(0
-nitrostyryl)-3-ethylbenzothiaturium・
P-toluenesulfonate (D-14) 2-(P-nitrostyryl)-quinoline P-)luenesulfonate (D-15) Phenosafranine -(D-16)
Pinacryptol Green (D-17) 2.3
-dimethyl-6-ditropenzothiazorium P-)
The amount of luenesulfonate organic desensitizer is the most important component of the present invention and is significantly lower than the amount previously used.

It should be understood that typical examples include amounts of organic desensitizer of less than 1 kg per mole of silver halide. Although it cannot be specified in general because it varies depending on the type of organic desensitizer and the properties of the silver halide emulsion, it is generally about 90°01 to about 30 milligrams per mole of silver halide, preferably about 0.1 mg. ~Approximately 10 milligrams. However, the amount of organic desensitizer may increase the inherent sensitivity of the silver halide emulsion used in the present invention by exceeding ogB = 1.3 (with the exception of salt (in the case of arsenic emulsion) Ogg = i, o). decrease with no value,
In other words, it is appropriate to specify that it is necessary to prevent the angle from decreasing to 1/2° or less (1/1o or less in the case of a silver chloride emulsion).

Generally, J o g E + 0.2 to J o g E =
1.3 (1.0 for silver chloride emulsions), preferably J o
g III+0.3~7! This is the amount necessary to reduce the concentration within the range of o g E = 1.0 (0.9 for silver chloride emulsions).

The organic desensitizer can be added at any time before coating the silver halide holes mJ.

The silver halide emulsion used in the present invention is a negative emulsion of silver chloride, silver chlorobromide, silver chloroiodide, or silver chlorobromoiodide containing at least 70 mol%, preferably 80 mol% of silver chloride. . The negative emulsion is a normal type of silver halide emulsion that forms a negative image on a positive I-tub, which is distinguished from a direct positive silver halide emulsion. Silver iodide is 0 to about 3 mol%,
Preferably it is 0 to about 1.5 mol%.

The silver halide emulsion used in the present invention has an average grain size of 0.
It is 1 to 0.4 μm. 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 silver halide emulsion may be prepared by any known method such as forward mixing, back mixing, and simultaneous mixing.

It is preferable that the emulsion that has undergone physical ripening is desalted and then coated with necessary additives, but the desalting treatment can also be omitted.

Although it is preferable not to substantially carry out chemical sensitization, it may be carried out if desired.

The silver halide emulsion obtained according to the present invention contains stabilizers, antifoggants, covering power improvers, Irradishi B
It can contain additives used in general photographic emulsions, such as coating inhibitors, film property improvers, surfactants, hardeners, matting agents, developing agents, etc., and when coated on a known support. It may have other hydrophilic colloid layers such as an Fi-retaining layer and a lower Mi layer.

The photosensitive material for bright room use obtained by the present invention is exposed to light using a light source rich in ultraviolet light mainly used in the printing field, such as an ultra-high pressure mercury lamp, metal halide, etc. Since the sensitivity is more than twice as high, the exposure time can be shortened and the illuminance can be lowered, making it possible to streamline operations such as saving power and shortening work time.

(Example 1) A silver chlorobromide emulsion containing 92 mol % of silver chloride was prepared by a simultaneous mixing method to obtain a monodisperse emulsion with an average grain size of 0.2 μm. The gelatin used (1, is inert gelatin. This emulsion was desalted and redissolved, so stabilizers, hardeners, and surfactants were added, and it was protected as silver nitrate on a polyester film so that it became 5117 m'. Coated with layer gelatin and dried.

Let this be blank sample A ◎ 1 mole of halogenated scissors #
Sample B was prepared in the same manner as blank sample A except that 5 x 10 ''-' moles of rhodium was used when mixing.Also, halogenation of blank sample HA←organic desensitizer (D- 2) or (D-9) per mole of silver halide as shown in Table 1 below.
Samples 0 to P were prepared in the same manner as above.

Table 1 These samples were exposed for sensitometry using a bright room printer equipped with a 1.5 KW ultra-high pressure mercury lamp, and developed with D-85 developer at 20°C for 2 minutes to remove the mud layer. and dried. Gradation gamma (r), maximum transmission arc praa
x) and relative sensitivity (8) are shown in Table 2. In addition, the minimum transmission density If (pmtn) was 0.02 for all samples ◇ Also, the relative sensitivity (l is 10 for blank sample A,
It is shown as a relative value when it is set to 000.

Furthermore, these samples were exposed to bright room light with 500 lux of ultraviolet light removed, that is, Toshiba PL408. Table 2 shows the capri values (B'') obtained after one hour of irradiation with a WNU fluorescent knife and the same development process as above (including Dmln). After applying metric exposure, irradiate for 10 minutes under the bright room light as described above, then 4k
Table 2 shows the desensitization rate (ratio of desensitization with the sensitivity of each sample developed immediately after sensitometric exposure as 100; ΔS) when developed. Comparative sample B, which uses the same compound, shows significant fogging under bright room light, and this capri increases as the amount of rhodium-4 is reduced.

Sample 0.g of the blank sample was reduced using organic desensitizers (D-'2) or (D-9) to values greater than ogH:1.3. It can be seen that D, E, J, L and M exhibit significant desensitization under bright room light. In contrast, sample F of the present invention
, G, H, I, N, O, and P have virtually no fogging or desensitization under bright room light despite their extremely high sensitivity, and also have high gradation and maximum density, making them extremely It can be seen that this is a highly sensitive light-sensitive material with excellent brightness.

Implementation fl12 As organic desensitizers (D-7), (D-10), (D-1
Example 1 was followed except that 1), (D-13) or (D-16) was added in an amount of 1 q per mole of silver halide (
The samples are sequentially Q, 几, 8. T.

Let it be U. ) Table 3 Example 3 Samples were prepared as described below in the same manner as in Example 1 except that silver chloride with an average grain size of 0.3 μm was used.
Table 4 shows the results of tests conducted in the same manner as above.

Table 4 In Table 4, samples g and h whose sensitivity (S) was decreased to a value not exceeding ogE = 1.0 are high-g and capri under bright room light, without desensitization. That is understood.

(Advantageous Effects of the Invention The silver halide photographic emulsion of the present invention has high contrast and a flat maximum density, has significantly higher sensitivity than conventional photosensitive materials for bright rooms, and has high sensitivity before and after image exposure. Since it does not have the drawbacks of capri generation and desensitization under bright room light, long-term handling safety can be ensured, and furthermore, it can save power and improve workability of the printer.

Claims (1)

[Claims] (1) A negative-working fine-grain silver halide photographic emulsion containing at least 70 mol % of silver chloride and a desensitizer, wherein the desensitizer is an organic desensitizer in which the sum of the anode potential and cathode potential of the polarograph is positive. The amount of the organic desensitizer reduces the sensitivity of the emulsion by logE=1.3 (however, in the case of silver chloride, logE=1.3
gE=1.0).