JPS5945134B2 - silver halide photographic emulsion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to silver halide photographic emulsions sensitized by dithiazolidine compounds.

Many chemical sensitization methods are known in the production of silver halide photographic emulsions to increase their photographic sensitivity.

For example, compounds containing unstable sulfur atoms in their molecules such as sodium thiosulfate and thiourea are known as sulfur sensitizers, and reducing agents such as stannous chloride and hydrogen are known as reduction sensitizers. It is being Further, the inclusion of certain gold compounds such as gold chloride and gold ammonium thiocyanide in the emulsion also has a chemical sensitizing effect, which is known as gold sensitization.
In fact, these compounds may be added at any stage for preparing the photographic emulsion, for example, as a ripening additive before the second ripening, or as a additive after the second ripening. A disadvantage of these chemical ripening agents is that the increase in sensitivity they provide tends to cause uniform fogging on the emulsion during development.

In other words, the fog accompanying the addition of a chemical sensitizer limits the amount of the sensitizer used, or the increase in sensitivity caused by them is insufficient, so that the practical requirements are not fully met. I can't say that there is. The present invention provides a silver halide photographic emulsion containing a novel sulfur sensitizer that does not have the above-mentioned drawbacks.

The present inventors investigated the sensitizing effect of various sulfur-containing compounds and found that the general formula / \ R-N=C5 ( ( R-NC=X [However, R in the formula is a hydrogen atom, It is an alkyl group having 1 to 6 carbon atoms or a phenyl group, and X represents a sulfur atom or an oxygen atom.

It has been found that all the emulsions containing the dithiazolidine compounds shown in the following form exhibit a good sensitizing effect and have very little fog. Specific examples of dithiazolidine compounds used in the silver halide photographic emulsion of the present invention are shown below.

/SN/゜＼(1)HN:C5(2)CH3-N=C5
H-N-C=5CH3-N-C■S (3)/SN C2H5-N:CS C2H|-N-C=5 The amount of dithiazolidine compound used in the emulsion of the present invention depends on the type of silver halide. Or, although it varies depending on the desired effect etc., it is usually 0.5W per mole of silver halide.
Preferably, a range of 9 to 50 watts is used.

The compound can be dissolved in a photographically acceptable organic solvent such as methanol or ethanol and added to the photographic emulsion. The dithiazolidine compound used in the emulsion of the present invention is preferably added to the silver halide photographic emulsion at the start of the second ripening. Sensitizers and the like can also be added before, during or after the second ripening. The type of emulsion used in the present invention is not particularly limited, and for example, silver chloride, silver bromide, silver chlorobromide, or silver iodobromide emulsion can be used. In addition to gelatin, these emulsions may contain a suitable hydrophilic binder depending on the purpose. Suitable binders include polyvinyl compounds, cellulose derivatives, polyacrylamide, other water-soluble synthetic polymers, and water-insoluble synthetic polymers. The end use of the emulsion coating layer is also not limited, such as black and white photography, color photography, microfilm, X-ray detection,
Furthermore, it can be used as an emulsion for a diffusion transfer method. The photographic emulsion of the present invention also contains various additives used in ordinary photographic emulsions, such as stabilizers, hardeners, X-ray absorbers, toning agents,
It can contain curing inhibitors, couplers, sensitizing dyes, surfactants, thickeners, development rate regulators, and the like.

The silver halide photographic emulsion prepared as described above exhibits excellent photographic performance with little fogging and is effectively sensitized.

Examples will be described below, but the present invention is not limited thereto.

Example-1 The average particle diameter was 0.00 mm produced by the usual double jet method.
A 4μ silver bromide emulsion was heated to pH 6. O, PAg6.3
and divided into four.

The first part contains dithiazolidine compound (1) 6.8W9 per mole of silver bromide, the second part contains 4.8W9 of dithiazolidine compound (4), and the third part contains dithiazolidine compound (7W9). ) were added, each dissolved in methanol, and no dithiazolidine compound was added to the fourth portion. These were named Emulsions 1, 2, 3, and 4, respectively.
After aging the above four emulsions at 50°C for 60 minutes, 40°C
PAg8. The solution was adjusted to 0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000. Table 1 shows the photographic properties after heating at 50° C. and 50% relative humidity for 24 hours.

As is clear from the results, it can be seen that the sensitivity of Emulsions 1 to 3 of the present invention is greatly increased compared to Comparative Emulsion 4, with almost no fog occurring.

Example 2 A silver bromide emulsion prepared in the same manner as in Example 1 was heated to pH 6. O,. The pAg was adjusted to 6.3 and divided into two.

In the first part, 17 sodium thiosulfate per mole of silver bromide, in the second part, 6 parts dithiazolidine compound (1).
．． 8, respectively, were dissolved in water and methanol, and 13 m of 0.1% AuCl3 aqueous solution was added to each.
After ripening the above two emulsions at 50°C for 60 minutes, PAg8. The solution was adjusted to 0.0 and added with ordinary surfactants and hardeners, and then applied to polyester.

When the photographic properties of the emulsion were examined after being heated for 24 hours at 50°C and 50% relative humidity, almost no fog occurred, and the relative sensitivity of Emulsion 5 as a comparison was 1,080. In comparison, Emulsion 6 of the present invention had a sensitivity of 1,350, and this result also shows that the sensitivity is high.

Claims (1)

[Scope of Claims] 1. A silver halide photographic emulsion characterized by containing a compound represented by the following general formula. General formula ▲ There are numerical formulas, chemical formulas, tables, etc. ▼ [However, R in the formula is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group, and X represents a sulfur atom or an oxygen atom. ]