JPH0436373B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to direct positive silver halide emulsions, and more specifically, the present invention relates to direct positive silver halide emulsions, and more specifically, the 3-position of the 5,6-dihydropyrrolo[2,1-a]isoquinoline ring and the 1,2-, The present invention relates to direct positive silver halide emulsions spectrally sensitized by novel dyes linked at the 3, 4 or 9 positions by dimethine chains. Direct positive images can be produced using certain silver halide photographic emulsions. For example, US Patent No.
As described in US Pat. No. 3,501,307, there are silver halide photographic emulsions that are fogged using a combination of an electron acceptor and a reducing agent with a metal compound that is more electrically positive than silver. Spectral sensitization technology is used to increase the sensitivity of this type of direct positive silver halide photographic emulsion. Many dyes are known as spectral sensitizing dyes for ordinary negative emulsions, but when these dyes are used directly for spectral sensitization of positive silver halide photographic emulsions, there are many drawbacks, such as changes in characteristic curves. This often results in softening and reversal. In addition, many proposals have been made as spectral sensitizers for direct positive silver halide photographic emulsions.
The reality is that there are few that have a satisfactory sensitization rate. In recent years, in addition to conventional tungsten and xenon light, the light sources used in photographic materials have come to include light sources emitted from lasers and diodes as information processing speeds up, and there is a demand for higher sensitivity in photographic materials. is increasing. The present inventors have conducted extensive research to obtain a direct positive sensitizing dye with a high sensitization rate, and have succeeded in obtaining a sensitizing dye that satisfies this objective. The novel sensitizing dye used in the present invention that satisfies the above objectives is 5,6-dihydropyrrolo[2,
1-a) A dye in which the 3-position of the isoquinoline ring and the 1, 2, 3, 4, or 9-position of a 5- or 6-membered nitrogen-containing heterocycle are bonded via a dimethine chain, and is represented by the following general formula. . general formula In the formula, R ₁ and R ₂ each represent hydrogen, an alkyl group (e.g., methyl, ethyl, propyl, isopropyl, butyl, tert, butyl, pentyl, hexyl, etc.), a cycloalkyl group (e.g., cyclopropyl, cyclohexyl, etc.), or an aralkenyl group. groups (e.g. styryl, etc.), aryl groups (e.g. phenyl, O-tolyl, m-tolyl, p-tolyl, p-
tert, butylphenyl, O-methoxyphenyl,
p-methoxyphenyl, p-tert, octyloxyphenyl, m-chlorophenyl, p-chlorophenyl, O-fluorophenyl, m-nitrophenyl, p-nitrophenyl, m-acetamidophenyl, p-benzamidophenyl, 3-chloro-4-ethoxyphenyl, 4-methyl-3-nitrophenyl, 4-benzyloxy-3-bromophenyl, 5-chloro-4-methoxyphenyl,
3,5-dichloro-4-ethoxyphenyl, m-
Sulfophenyl, m-fluorosulfonylphenyl, 3,5-difluorosulfonylphenyl, 2
-methoxy-5-fluorosulfonylphenyl,
p-cyanophenyl, p-carboxyphenyl,
p-ethoxycarbophenyl, etc.), 5- or 6-membered heterocyclic groups (e.g., 2-furyl, 3-pyridyl,
4-pyridyl, etc.), and R ₃ is the above R ₁ and
Alkyl groups and substituted alkyl groups as mentioned in R ₂ (e.g., hydroxyalkyl groups such as β-hydroxyethyl, r-hydroxypropyl, etc., acyloxyalkyl groups such as β-acetoxyethyl, r-acetoxypropyl, β-benzoyloxyethyl, etc.) , β-methoxyethyl, β-ethoxyethyl,
Alkoxyalkyl groups such as β-isopropoxyethyl, carboxyalkyl groups such as carboxymethyl, β-carboxyethyl, r-carboxypropyl, alkoxycarbonylalkyl groups such as methoxycarbonylmethyl, ethoxycarbonylmethyl, β-ethoxycarbonylethyl, β -sulfophenyl, r-sulfopropyl, δ-sulfobutyl, etc.), alkenyl groups (eg, allyl, etc.), and aralkyl groups (eg, benzyl, phenethyl, etc.). Z represents a nonmetallic atomic group necessary to complete a 5- or 6-membered nitrogen-containing heterocyclic nucleus, which is well known in the chemistry of cyanine dyes; specific examples include oxazoline nucleus, dihydroxazine nucleus, and oxazole nucleus. , benzoxazole nucleus, naphthoxazole nucleus, oxazolopyridine nucleus, thiazoline nucleus, thiazole nucleus, benzothiazole nucleus, naphthothiazole nucleus, thiazolopyridine nucleus, selenazole nucleus, benzoselenazole nucleus, naphthoselenazole nucleus, pyridine nucleus, quinoline nucleus, isoquinoline nucleus, imidazole nucleus, benzimidazole nucleus, naphthoimidazole nucleus, indolenine nucleus, S-triazolo[2.3-a]pyridine nucleus, tetrazolo[a]pyrimidine nucleus, imidazo[4.5-b]quinoxaline nucleus, naphthyridine nucleus,
Examples include acridine nucleus, pyrroline nucleus, and 1,3,4-thiadiazole nucleus. X ^- is an acid anion (e.g.
m and n, which represent methyl sulfate ion, ethyl sulfate ion, thiocyanate ion, p-toluenesulfonate ion, chloride ion, bromine ion, iodide ion, perchlorate ion, etc., are each 1 or 2. Next, typical examples of dyes used in the present invention will be listed. Next, a typical example of the method for synthesizing the novel dimethine dye used in the present invention will be described. Synthesis of dye (15): 1-formyl-2-(p-nitrophenyl) 5,
6-dihydropyrrolo[2,1-a]isoquinoline
3.18g and 1,2,3,4,5-pentamethyl-
3.15 g of 3H-indolium iodide was reacted with 3.15 g of 3H-indolium iodide in 20 ml of acetic anhydride by heating under reflux for 10 minutes. After cooling, the precipitated crude dye was collected and washed with a small amount of ethyl acetate. Next, it was recrystallized with methanol to obtain golden columnar crystals with a melting point of 286.0°C (decomposition) after drying. Other dyes used in the present invention can also be easily synthesized according to the above synthesis example. The absorption maximum values (nm) of methanol solutions of the representative examples of the dyes used in the present invention are as follows.

[Table] In the present invention, a dimethine dye of the general formula can be added to a silver halide photographic emulsion by a known method. For example, it can be added as a solution in a solvent such as methanol, ethanol, isopropanol, pyridine, dimethylformamide, acetone, water, etc. alone or in combination. It can also be added to the emulsion using ultrasonic dispersion. Additionally, known methods for negative emulsions, such as U.S. Pat. No. 3,482,981, U.S. Pat.
No. 3649286, No. 3485634, No. 3485634, No.
The methods described in No. 3342605 and No. 2912343 can also be used. The amount of dimetine dye used in the present invention varies depending on various factors of the silver halide photographic emulsion, but is preferably 1×10 ^-5 to 2×10 ^-2
The range is mole/moleAg. Although the dye can be added to the emulsion at any stage of emulsion preparation, it is particularly preferred to add the dye immediately before coating. Silver halide photographic emulsions used in the present invention include silver chloride, silver bromide, silver chlorobromide, silver iodide, silver chloroiodobromide, and silver iodobromide emulsions. In order to obtain a high-sensitivity direct positive silver halide photographic emulsion,
Silver halide photographic emulsions containing 80 mol % or more of bromide are preferred. The silver halide photographic emulsion used in the present invention includes both monodisperse and non-monodisperse emulsions, but monodisperse emulsions are more preferred. Further, the silver halide photographic emulsion used in the present invention may have a cubic crystal habit or a regular octahedral crystal habit, but a cubic crystal habit is more preferable. Furthermore, the grains of the silver halide photographic emulsion used in the present invention are preferably regular. In the present invention, an emulsion having a nucleus for capturing free electrons inside a silver halide crystal and whose surface is fogged with a chemical fogging agent may be used. The preparation of this type of emulsion is described, for example, in US Pat. Nos. 3,367,778, 3,632,340 and 3,709,689. The silver halide photographic emulsion used in the present invention is
Fogged by light or chemical fogging agents. Methods of chemically imparting fog include, for example, Antoine Hautot and
Science et Industries Photographique by Henri Saubenier
Favorable results are obtained using the method of chemical sensitization described in Vol. 28, pp. 57-65 (published in 1957). The silver halide photographic emulsion used in the present invention can be fogged by a reducing agent. Specific examples of reducing agents include stannous chloride, thiourea dioxide, formalin, hydrazine and its derivatives,
Examples include amine borane. The silver halide photographic emulsion used in the present invention can also be fogged by gold compounds. Specific examples of the gold compound include chloroauric acid, potassium chloroaurate, potassium gold thiosulfate, and the like. The silver halide photographic emulsion used in the present invention can also be fogged by combining a reducing agent with a metal compound having a more noble potential than silver. Specific examples of metal compounds having a potential more noble than silver include, in addition to the gold compounds mentioned above, platinum compounds such as potassium chloroplatinate, and iridium compounds such as potassium hexachloroiridate. Furthermore, a silver halide photographic emulsion can be fogged by using the above method in combination with a sulfur-containing sensitizer such as sodium thiosulfate or allylthiourea, or a thiocyanic acid compound such as potassium thiocyanate. By combining the novel dimetine dye used in the present invention with a known organic desensitizing dye, a direct positive silver halide photographic emulsion with even higher sensitivity can be obtained. Known dyes that have been proposed as spectral sensitizers for direct positive silver halide photographic emulsions can be combined with known organic desensitizing dyes to further amplify the coloring (color staining) caused by the dyes remaining after development. However, the new dimetine dye used in the present invention is
Even when used in combination with known organic desensitizing dyes, it is extremely unlikely that the coloring (color stain) caused by the dyes remaining after the development process will be amplified. Specific examples of known organic desensitizing dyes used in the present invention include pinacryptol yellow, phenosafranin, methylene blue, pinacriptol green, 3-ethyl-5-metanitrobenzylidene rhodanine, 3,3'-diethyl- 6,
Examples include 6'-dinitrothiacarbocyanine iodide. Examples of the protective colloid used in the present invention include natural products such as gelatin, albumin, agar, gum arabic, and alginic acid, and water-soluble synthetic resins such as polyvinyl alcohol, polyvinylpyrrolidone, and cellulose ether. In the present invention, various additives such as stabilizers, brighteners, ultraviolet absorbers, hardeners, surfactants, preservatives, plasticizers, and matting agents can be included in the silver halide photographic emulsion. . Examples of the support used in the present invention include resin films such as polyethylene terephthalate and cellulose acetate, synthetic paper, and waterproof paper. Paper laminated with plastic can also be used. If necessary, a subbing layer can be provided on these supports by a known method. The light-sensitive material coated with the direct positive silver halide photographic emulsion of the present invention is processed using known processing baths for development, fixing, bleaching, etc., or a combination of these processing baths. The first feature of the present invention is that by spectral sensitization using a novel dimethine dye containing a 5,6-dihydropyrrolo[2,1-a]isoquinoline ring, a highly sensitive direct positive silver halide dye can be produced. The point is that a photographic emulsion can be obtained. The second feature of the present invention is that by using a novel dimethine dye containing a 5,6-dihydropyrrolo[2,1-a]isoquinoline ring, a high contrast direct positive silver halide photographic emulsion can be obtained. It is at the point where it can be done. Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is of course not limited thereto. Example 1 A silver iodobromide emulsion (2 mol % of iodine) was prepared using the control double run method. This raw emulsion has a cubic crystal habit and an average grain size of 0.25μ.
It was a monodisperse emulsion containing 95% by weight of grains within 30% of the average grain size. After precipitating and washing with water, gelatin was added, pH was adjusted to 8.0 and pAg was adjusted to 5.0, 2 mg/moleAg of potassium chloroaurate was added, and the mixture was heated at 60°C for 2 hours. Then, adjust the pAg to 8.5 and pH to 5.0, divide the sample, and add 350 mg/dimetine dye.
moleAg was added. In addition, pinacryptol
Yellow 200mg/moleAg was added, a hardener and a surfactant were added, and the paper support was laminated with subbed polyethylene in terms of silver nitrate.
It was applied at a coating weight of 3.7 g/m ² . After drying, each sample was cut into appropriate sizes and exposed through a wedge with a density difference of 0.15.
72 developer for 90 seconds at 20°C, fixed using an acidic fixer, washed with water, and dried. Table 1 was obtained as a result of concentration measurement. S in the table is a value measured at an optical density of 0.75, and is expressed as a relative value with the blank value as 1.0. γ represents the slope of the straight line between concentrations 0.5 and 1.5, and Dmin represents the minimum concentration.

[Table] As is clear from Table 1, the dimetine dye used in the present invention is characterized by excellent sensitization, high contrast photographic properties, and low minimum density. Therefore, by using the dimetine dye of the present invention, it is possible to obtain a direct positive silver halide photographic light-sensitive material with high sensitivity and high contrast. Example 2 A silver iodobromide emulsion (2 mol % of iodine) was prepared using a controlled double run method. This raw emulsion has a cubic crystal habit and an average grain size of 0.25μ.
It is a monodisperse emulsion containing 95% by weight of grains within 30% of the average grain size, and after growing to 0.16μ,
Potassium hexachloroiridate 50mg/
After adding moleAg and leaving it for 20 minutes at 60°C, double runs were continued to grow to 0.25μ. After settling and washing with water, add gelatin and adjust the pH to 6.5.
Adjust pAg to 6.2 and thiourea dioxide 0.2mg/
moleAg was added and aged at 60°C for 1 hour, and potassium chloroaurate 2 mg/moleAg was further added and the mixture was heated at 60°C for 1 hour. After that, adjust the pAg to 8.5 and pH to 5.0, divide the sample, and add 350 mg/dimetine dye.
Table 2 was obtained in the same manner as in Example 1 by adding moleAg.

【table】

[Table] As is clear from Table 2, the dimetine dye used in the present invention has a 2 to 5 times higher sensitization and is characterized by providing high-contrast photographic characteristics. Therefore, by using the dimetine dye of the present invention, it is possible to obtain a direct positive light-sensitive material with high sensitivity and high contrast.

Claims (1)

[Scope of Claims] 1. The 3rd position of the 5,6-dihydropyrrolo[2,1-a]isoquinoline ring and the 1,2,3,4 or 9th position of the 5- or 6-membered nitrogen-containing heterocycle are bonded via a dimethine chain. 1. A silver halide emulsion for direct positive use, characterized in that it contains at least one dye having the following properties.