JPS63243937A - Direct positive silver halide photographic emulsion - Google Patents

Abstract

PURPOSE:To obtain the titled emulsion having high sensitivity and low fogging by incorporating at least one kind of an org. desensitizer having a prescribed composition, in the titled emulsion. CONSTITUTION:The titled emulsion contains at least one kind of the org. desensitizer shown by formula I wherein R is alkyl group, at least one of R<1>-R<5> groups is an electron attractive group having the delta value of Hammett's rule of >=0.21, and may be the same or the different with each other, and the remainder groups are hydrogen atom or alkyl group, Z is an atomic group necessary for completing a 5 or 6 membered nitrogen-contg. heterocyclic ring group, X<-> is an anion. Thus, the titled emulsion having the high sensitivity and the less fogging is obtd. by using the desensitizer shown by formula I for an electron acceptor.

Description

Detailed Description of the Invention (A) Industrial Application Field The present invention relates to a direct positive silver halide photographic emulsion, and more specifically to a direct positive silver halide photographic emulsion using a novel organic desensitizer as an electron acceptor. This invention relates to silver halide photographic emulsions for use in commercial applications.

(B) Prior Art and Its Problems Direct positive images can be obtained using certain silver halide photographic emulsions. For example, there is a silver halide photographic emulsion comprising fogged silver halide and an electron acceptor, as described in US Pat. No. 3,501,307.

In order to increase the sensitivity of this type of silver halide photographic emulsion, selection of fogging agents and electron acceptors is important. Also used is the technique of spectral sensitization using dyes. Desensitizing dyes such as pinacryptol yellow and organic desensitizing agents such as paraquat are used as electron acceptors. However, many have low sensitivity and high fog levels, and there are few that surpass pinacryptol yellow.

(C) Purpose of the Invention The present inventors have conducted intensive research to produce a direct positive silver halide photographic emulsion with high sensitivity and low fog, and as a result, have succeeded in creating an organic desensitizer that satisfies this purpose. did.

Therefore, an object of the present invention is to provide a direct positive silver halide photographic emulsion with high sensitivity and low fog by using a novel desensitizer as an electron acceptor.

(D) Structure of the Invention The novel desensitizer used in the present invention is necessarily a compound represented by the general formula [E].

In the formula, R is an alkyl group (e.g., methyl group, ethyl group,
sulfopropyl group, etc.), and R1 to R5 may be the same or different, but at least one is a negative group having a Hammett's σ value of 0.21 or more. The rest are hydrogen atoms and alkyl groups. Z represents an atomic group necessary to complete a 5- or 6-membered nitrogen-containing heterocycle. Specific examples of the heterocycle include a quinoline ring, a benzothiazole ring, an indolenine ring, a benzoxazole ring, a benzimidazole ring, an acridine ring, an imidasoquinoxaline ring, a 1,8-naphthyridine ring, and a benzo(f ) quinoline ring, oxazole ring, thiazole ring, etc. X- is an anion;
Indicates halide anion, sulfonate anion, perchlorate, fluoroborate, etc.

Next, typical examples of organic desensitizers used in the present invention will be listed.

(Hereinafter in the margin) Dodo■- Dododo (hereinafter in the margin) Next, a typical example of the method for synthesizing the novel organic desensitizer used in the present invention will be described.

Synthesis of compound (4) 0.885 g of P-nitrocinnamaldehyde and 1.72 g of 6-ethoxy-N-ethylquinaldinium iodide
5g to acetic anhydride 67! The mixture was heated under reflux for 30 minutes. After cooling, the precipitated crystals were collected by filtration, washed with ethanol, and then recrystallized from methanol.

Collection ffl 386Irtg mp 248° (dec) eOH λ 410nm ax Synthesis of compound (9) 0.785 g of P-cyanocinnamaldehyde and 6-ethoxy-N-ethylquinaldinium ice "Dite 1.
725 g was heated under reflux for 30 minutes in 6 d of acetic anhydride. The cooled shun crystals were collected by filtration, washed with ethanol, and then recrystallized from methanol.

Recovery 234 mFI mp 250'-252° (dec) cal λ 4120 m aX Synthesis of compound (14) 1.355 g of anhydro 2-methyl-1-(3-sulfopropyl)thiazonium hydroxide and P-nitrocin 0.885 g of aldehyde was heated under reflux for 1 hour in acetic anhydride solution. After cooling, the precipitated crystals were collected by filtration and washed with methanol.

Yield 559 m'j mp 228° (dec) eOtl λ 404 n1lt aX Other desensitizers used in the present invention can also be easily synthesized according to the above synthesis example.

In the present invention, an organic desensitizer can be added to the 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.

The addition ω of the desensitizer used in the present invention varies depending on various factors of the silver halide emulsion, but is preferably 1Xl 0-5 to 2X10-211101e/mol.
e is in the range of Aa.

Although the desensitizer can be added to the emulsion at any stage of emulsion production, it is particularly preferred to add it 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.

High-sensitivity direct positive silver halide photographic emulsion.

A silver halide photographic emulsion containing 80 mol % or more of bromide is preferable.

The silver halide photographic emulsion used in the present invention includes:
It includes both monodisperse and non-monodisperse,
Monodisperse ones are more preferable.

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 production of this type of emulsion can be done by e.g.
U.S. Patent No. 3,367.778, U.S. Patent No. 3,632,34
No. 0 and No. 3,709,689.

The silver halide photographic emulsion used in the present invention is
Fogged by chemical fogging agents.

Methods of chemically imparting fog include, for example, Antoine Haut and Henri Ichiban Sauvenil.
Science et Industry Photographic (Science et Industry Photographic)
es Photographique) Volume 28, 57~
Favorable results are obtained using the method of chemical sensitization described on page 65 (published in 1957).

The silver halide photographic emulsion used in the present invention can be fogged by a reducing agent.

Specific examples of the reducing agent include stannous chloride, thiourea difluoride, formalin, hydrazine and its derivatives, and amineborane.

The silver halide photographic emulsion used in the present invention can also be fogged by a gold compound.

Specific examples of the gold compound include chloroauric acid, potassium chloroaurate, potassium 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.

As specific examples of metal compounds having a potential more noble than silver potential, in addition to the above-mentioned gold compounds, platinum compounds such as platinum potassium chloride and iridium compounds such as potassium hexychloroiridate are used.

Furthermore, a silver halide photographic emulsion can be fogged by using the above method in combination with a sulfur-containing sensitizer such as monohelium thiosulfate or allylthiourea, or a thiocyanate compound such as potassium thiocyanate.

Examples of the protective colloid used in the present invention include natural products such as gelatin, albumin, agar, gum arabic, and alginine, and water-soluble synthetic resins such as polyvinyl alcohol, polyvinylpyrrolidone, and cellulose ether.

In the present invention, stabilizers, brighteners, ultraviolet rays, absorbers,
Various additives such as hardeners, surfactants, preservatives, plasticizers, and hardening 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-1, 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 such as development, fixing and bleaching, or a combination of these processing baths.

A feature of the present invention is that a novel loaded desensitizer is used as an electron acceptor, and a direct positive silver halide photographic emulsion with high sensitivity and low fog can be obtained. Hereinafter, the present invention will be explained based on Examples, but the present invention is not limited thereto.

(E) Examples Example 1 A silver iodobromide emulsion (2 mol % of iodine) was prepared using a controlled double run method. This raw emulsion was a monodisperse emulsion with a cubic crystal habit, an average grain size of 0.25 μm, and a grain size of 95% by weight within 30% of the average grain size. After precipitation and washing with water, piratin was added and the pH was adjusted to 8.0. P
Adjust the Ag to 5.0, and adjust the chloroauric acid strength to 1. J Ram 2m
l/mole A (J) was added and incubated at 60'C for 2 hours.Then, PA() was adjusted to 8.5 and pH to 5.0, the sample valve was divided, and organic desensitizer 200mg/mole was added.
A paper support laminated with polyethylene which had been subbed with addition of Ag, a hardening agent and a surfactant, was coated at a coating m of 3.1/m in terms of silver nitrate. After drying, each sample was cut into appropriate sizes and exposed through a wedge with a density difference of 0.15.
2 developer for 90 seconds at 20'C, fixed using an acidic fixer, washed with water, and dried. As a result of concentration measurement, Table 1 was obtained. S in the table is a value measured at an optical degree of 0.75, and is expressed as a relative value with the value of compound A (paraquat) being 1.0. Further, Dmin represents the minimum concentration.

Compound A 8r- Also, for comparison, pinacryptol yellow (compound B
) values are also shown.

Compound B Cth CH30SO Table 1 Example 2 A silver iodobromide emulsion (
2 mol% of iodine) was prepared. This raw emulsion is a monodispersed emulsion with a cubic crystal habit and an average grain size of 0.25μ, containing 95% by weight of grains within 30% of the average grain size. , potassium hexachloroiridate 50mg/mole Ag was added, 6
After standing at 0°C for 20 minutes, double run was continued and 0.
It was grown to 25μ. After precipitation and water washing, gelatin was added to adjust II to 6.5 and PAg to 6.2, thiourea dioxide 0.2/72g/mole Ag was added, and the mixture was aged at 60°C for 1 hour. acid potassium 2m
g/mole A (I) was added and incubated at 60'C for 1 hour. After that, PA () was adjusted to 8.5 and DH to 5.0, the sample valve was divided, and the desensitizer was added to 35 omy/mole. mole
After adding Ag, 1q of Table 2 was obtained in the same manner as in Example 1.

(Leaving space below) Table 2 (F) As is clear from the effect table of the invention, the organic desensitizer of the present invention has an excellent electron capture ability, and a direct positive silver halide photographic emulsion with high sensitivity and low fog is produced. can get.

In addition, if used in combination with a sensitizing dye, it is also possible to obtain a more highly sensitive direct positive silver halide photographic material.

Claims (1)

[Claims] (1) A direct positive silver halide photographic emulsion characterized by containing at least one organic desensitizer represented by the general formula [I]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼General formula [I] (In the formula, R represents an alkyl group.R^1 to R^5 may be the same or different, but at least one has Hammett's σ It is an electron-withdrawing group with a value of 0.21 or more.The remainder are hydrogen atoms and alkyl groups.Also, Z represents an atomic group necessary to complete a 5-membered or 6-membered nitrogen-containing heterocycle. X^- indicates an anion.)