JPS61196238A - Preparation of silver halide photographic emulsion - Google Patents

Abstract

PURPOSE:To obtain a spectrally sensitized silver halide photographic emulsion high in sensitivity and contrast by incorporating a sensitizing dye at the time of completing the first ripening stage of photosensitive silver halide grains. CONSTITUTION:The sensitizing dye is added when the first ripening stage has been substantially finished in a manufacturing process of the photosensitive silver halide photographic emulsion, that is, when the intended silver halide grains have been almost formed, and at the time prior to emulsion precipitation and water rinse steps. When these steps are not necessary, the dye is added at the time of finishing formation of most of silver halide grains. Conventionally used sensitizing dyes may be used for said dye. When a cyanine dye is used, especially when the cyanine dye is added in an emulsion to be prepared by the ammoniacal process, the most remarkable effect can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a method for producing a spectrally sensitized silver halide photographic emulsion with high sensitivity and high contrast.

(B) Prior Art and its Problems In general, many methods have been known to increase the sensitivity of silver halide photographic materials.

For example, spectral sensitization using sensitizing dyes, noble metal sensitization using compounds of noble metals such as gold, platinum, and iridium, thiourea,
Sulfur sensitization using metal sulfide such as Hypo, monovalent silver salt,
Reduction sensitization using polyamines, hydrazine derivatives, etc., or quaternary ammonium salts.

Methods such as development acceleration using polyalkylene glycol and the like are known. In actual photographic emulsions, sensitization is carried out by appropriately combining these sensitization techniques. However, there are certain limits to sensitization by these sensitizations or a combination of them, and if you try to further increase the sensitivity, the capri will increase, the tone will become soft, and storage stability will deteriorate. What difficulties do you encounter? Various proposals have been made in the past regarding spectral sensitization using sensitizing dyes, such as Japanese Patent Application Laid-Open No. 55-26589. A method of adding a sensitizing dye during the first ripening of silver halide is disclosed in Japanese Patent Publication No. 58-184142. However, these proposals were not sufficient methods for obtaining satisfactory sensitivity. Also second
The addition of sensitizing dyes during ripening and after the second ripening was also disclosed in JP-A-58-
No. 7629, etc., but these were not fully satisfactory in terms of sensitivity and dye removal after development of the sensitizing dye.

(C) Purpose of the Invention The purpose of the present invention is to provide a method for producing a spectrally sensitized silver halide photographic emulsion with high sensitivity and high contrast.

(D) Structure of the Invention While taking into account the shortcomings of the prior art that the present inventors are familiar with, the present inventors have worked diligently to obtain a silver halide photographic emulsion with high sensitivity, high contrast, little fog, and good dye removal after processing. As a result of repeated research, we have discovered that the above-mentioned drawbacks can be improved by adding the light-sensitive silver halide grains at the substantial completion of the first ripening in the process of producing light-sensitive silver halide photographic emulsions.

The silver halide emulsion used in the present invention is prepared by acid method-1, (
The above-mentioned effects can be obtained regardless of whether it is produced by the neutral method or the ammonia method, but the effect is particularly remarkable when it is produced by the ammonia method.

The present invention is concerned with the properties of silver halide grains, such as the composition of silver halide (for example, silver bromide, silver chloride, starved silver chlorobromide, silver chloroiodobromide, crystal form and crystal habit of silver halide). , particle size distribution,
It is possible to implement regardless of size etc.

In the present invention, the sensitizing dye is added substantially at the end of the first ripening. That is, this is the time when the formation of the desired silver halide grains is almost completed and before the emulsion precipitation and water washing steps.

If emulsion precipitation and water washing steps are not required, this is the time when the formation of silver halide grains is almost completed.

The silver halide grains used in the present invention may be produced by any method such as a single jet method, a double jet method, a Chondrald double jet method, etc.
The particles may be produced by a core-shell type, an epitaxial growth type, a conversion method, or the like.

The emulsion obtained according to the present invention may contain various additives. For example, chemical sensitizers (for example, sulfur sensitizers such as thiourea and hypo, noble metal sensitizers such as platinum iridium compounds, and reduction sensitizers) can also be used in combination. Spectral sensitizers used in addition methods other than the present invention 9 supersensitizers, stabilizers, anti-capri agents, surfactants, present agents, present accelerators, hardeners, hardening accelerators, couplers , a desilvering accelerator, a dye removal improver, a whitening agent, a thickener, etc. may be contained.

Protective colloids for the silver halide emulsion in the present invention include gelatin, modified gelatin, and albumin.

Examples include natural products such as agar, gum arabic, and alginic acid, and water-soluble synthetic resins such as polyvinyl alcohol, polyvinylpyrrolidone, and copolymers of acrylamide, acrylic acid, and vinylimidazole.

The support for coating the emulsion according to the present invention is not limited to film, paper, synthetic paper, laminated paper, metal, etc., and may be corona-treated by a known method if necessary. Well, I must see you again! Depending on the situation, undercoat processing may be performed using a known method.

The exposure of the silver halide photographic material according to the present invention obtained by coating is not limited to light only, but also to one line #rl! The effects of the present invention are noticeable even when exposed to an electron beam or the like.

The silver halide photographic emulsion according to the present invention is coated together with an insulating layer, an intermediate layer, an ultraviolet absorption layer, an undercoat layer, or other silver halide emulsion, if necessary. The silver halide photographic material to which the present invention can be applied is not particularly limited in type or use, such as black and white photographic material, color photographic material, general use, printing agent use, etc.

The sensitizing dye used in the present invention is not particularly limited, but any commonly used sensitizing dye may be used.

Examples of the sensitizing dyes used in the present invention include shea=y dyes, styryl dyes, hemicyanine dyes, triphenylmethane dyes, xanthine dyes, oxonol dyes, and merocyanine dyes. In the present invention, when a cyanine dye is used, the most remarkable effect is obtained, especially when the cyanine dye is added substantially at the end of the first ripening in an ammonia method emulsion.

The sensitizing dye used in the present invention can be used alone even if it is used alone.
It may be used in combination with more than one kind or with a supersensitizer or the like. Specific examples of the sensitizing dye used in the present invention include, but are not limited to, 2H5 503-S03. As mentioned above, cyanine dyes are particularly preferred. Examples will be described below to more specifically explain the present invention, but the present invention is of course not limited thereto.

Example I Keep the liquid at 40°C and add the liquid while stirring vigorously.
After adding 1 minute diameter solution (■) and aging at 40°C for 9 minutes, solution (2) was added, p) (=3.Q), and after dividing, sensitizing dyes were added as shown in Table 1 (A period).

An aqueous sodium sulfate solution was added to this to precipitate it, which was washed with water. This raw emulsion had an average grain size of 0.45 μm, a crystal habit of mainly cubes, and was a chloroiodobromide emulsion containing 95 moles or more of bromide.

This raw emulsion was redissolved, gelatin was added, the pH was adjusted to 6.0, and then sensitizing dyes were added as shown in Table 1 (period B). IJum and 1° of chloroauric acid per mole of silver halide were added, and chemical ripening was carried out at 60° C. for 60 minutes. After ripening, 1-phenyl-5-mercaptotetrazole was added per mole of silver halide D20011F. After adding sensitizing dyes as shown in Table 1 to these emulsions (C period: hardener and surfactant), the emulsions were dried.The amount of silver coated was 2.4 ν.

Each sample thus prepared was cut into an appropriate size, and one of the samples was exposed through a wedge with a density difference of 0.15, and then developed. The other sheet was stored for 4 days at 50°C and 5OSRH, then exposed and developed. Development was carried out at 20° C. for 2 minutes using a developer having the following composition.

Water (approximately 80℃) 500m meters
31g hydroquinone
12g anhydrous sodium sulfite 4
5g anhydrous sodium carbonate 67.5g potassium bromide 1.9g Add water
After 30,000 sd, it was stopped, fixed, washed with water, and then dried.

Table 1 shows the sensitivity (relative tone (γ) and capri) obtained as a result of concentration measurement.

(Left below) As is clear from Table 1, this product #J1. 4. 7 had higher sensitivity, higher contrast, and less fog than comparisons 2, 3, 5, 6, 8, and 9. In addition, regarding dye loss after development, the present invention 1. 4. 7 was better than comparison 2, 3, 5, 6°8.9.

Example 2 An emulsion was prepared according to the following formulation.

■ [6N sulfuric acid solution V was kept at 60°C, and while stirring strongly, solutions (■) and (2) were added at the same time over 30 minutes, and the PAg during this period was 7.
4 to control friend. Five minutes before the end of mixing, the sensitizing dyes shown in Table 2 were added in an amount of 0 Schiff per mole of silver halide. Thereafter, solution (2) was added to adjust the pH to 3.5K to cause precipitation, which was then washed with water. This raw milk 1 is a silver iodobromide emulsion containing 97.5 mol of bromide, and has an average grain size of 0.25 μm.
It is a cubic monodisperse emulsion containing 95% by weight or more of grains within ±20% of the average grain size. This raw emulsion was redissolved and sensitizing dyes were added as shown in Table 2. Next, gelatin was added to adjust the pH to 6.5 K, and then 40 caps of sodium thiosulfate per mole of silver halide and 15 caps of ammonium gold thiocyanate per mole of silver halide were added and heated at 55°C for 60 minutes. It was matured. After ripening, 1-7enyl-5-mercaptotetrazole was added in an amount of 100 caps per mole of silver halide. A hardener and a surfactant were added to these emulsions, which were coated on a polyethylene terephthalate film and dried. The amount of silver coated is 3.0 g/rr? Met.

Each sample thus prepared was treated in the same manner as in Example 1. Table 2 shows the sensitivity (relative value), capri, and dye loss obtained as a result of reflection density measurement.

Samples 2, 5, 8, and 11 had the same particle size and crystal habit as 3, 6, and 9.12, respectively, as a result of comparison using electron micrographs, but samples 1, 4, and 7.10 had smaller particle sizes. Ta.

(Margin below) As is clear from Table 2, the invention 2.5.8.11 has higher sensitivity and lower fog than the comparison 1.3.4.6.7.9.10.12, and the dye The exit was also good.

The evaluation criteria for dye removal were as follows: ◯: Very good dye removal Δ: Practically acceptable range ×: Very poor dye removal and a range that cannot withstand practical use.

Claims (4)

[Claims] (1) In the manufacturing process of light-sensitive silver halide photographic emulsion,
A method for producing a silver halide photographic emulsion, characterized in that a sensitizing dye is added at the time when the first ripening of the light-sensitive silver halide grains is substantially completed. (2) The method for producing a silver halide photographic emulsion according to claim (1), wherein the first ripening of the light-sensitive silver halide photographic emulsion is an ammonia method. (3) The method for producing a silver halide photographic emulsion according to claim (1), wherein the spectral sensitizing dye is a cyanine dye. (4) The method for producing a silver halide photographic emulsion according to claim (2), wherein the spectral sensitizing dye is a cyanine dye.