JPS585420B2 - Direct positive silver halide photographic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Lith-type direct positive silver halide photosensitive material which provides a high contrast image when processed with a Lith developer.

Generally, in the field of graphic arts, high contrast photographic materials are used to photographically create line images and halftone images (halftone images).

An image is created on a Lith-type photographic material used for this purpose by exposing a continuous-tone original through a screen and then processing it with a Lith developer containing hydroquinone as a single developing agent.

In this way, the positive original is reproduced into a negative image and used for plate making in various processes.

One of these processes is the process of duplicating a reproduced negative image into a positive image using a negative-type photographic material.

In this process, processing is performed twice, from positive to negative to positive, but in recent years there has been a growing demand for obtaining an image with a single process from positive to positive.

Direct positive silver halide photosensitive materials such as duplicating films have conventionally been used in such positive-to-positive or negative-to-negative duplication processes.

However, when conventional direct positive silver halide photosensitive materials are processed with Lith developer, they produce softer images compared to commercially available Lith type photographic materials, and once the images are reproduced with Lith type photographic materials, Although it can be reproduced, it has been difficult to photographically create line images and halftone images (halftone images) by itself.

Silver halide emulsions containing silver bromide and silver iodobromide as main components are used in high-sensitivity direct positive silver halide photographic materials.

As described in Japanese Patent Publication No. 49-69330, when a silver halide photosensitive material containing silver bromide or silver iodobromide as a main ingredient is processed with a conventionally known Lith developer,
This resulted in a soft-toned image and was not used to obtain a high-contrast image.

Although this difficulty was solved by improving the processing method in the specification of Japanese Patent Publication No. 49-69330, there was no mention of direct positive silver halide photographic light-sensitive materials.

On the other hand, silver chlorobromide or silver chloroiodobromide emulsions containing silver chloride as a main ingredient have been used in commercially available lithium-type photographic materials.

The sensitivity of such emulsions can be increased by spectral sensitization, but the following conditions must be satisfied for lithium emulsions.

■Do not interfere with the photographic characteristics of extremely high contrast.

■The sharpness of the halftone image will not deteriorate, and the quality of the minute halftone dots will not be hindered from being improved.

■No pigment staining.

From this point of view, dyes such as merocyanine, inner salt cyanine, anionic cyanine, etc. have been selected, and
As described in Japanese Patent Publication No. 48-28224, these dyes can also be used in combination.

However, a high-sensitivity direct positive silver halide photosensitive material containing silver bromide or silver iodobromide as a main ingredient has not been disclosed.

Taking the above-mentioned technical background into consideration, the inventors of the present invention have made the following findings as a result of repeated research to develop a Lith type direct positive silver halide photographic material that provides high contrast images.

That is, by sensitizing a direct-positive silver halide emulsion containing silver bromide or silver iodobromide as a main component with an anionic cyanine dye, a lithium-type direct-positive silver halide photographic light-sensitive material can be obtained.

Therefore, a first object of the present invention is to provide a lithium-type direct positive silver halide photographic light-sensitive material that provides a high contrast image.

A second object of the present invention is to provide a highly sensitive lithium-type direct positive silver halide photographic material.

Other aspects and advantages of the present invention will become apparent from the following description.

The anionic cyanine dye used in the present invention has a polarographic oxidation half-wave potential more positive than +0.40V.

These anionic cyanine dyes are used as sensitizers in direct positive silver halide emulsions, and can be characterized by their polarographic oxidation half-wave potential and ring element half-wave potential.

It is known that there is a strong correlation between the spectral sensitization effect on direct positive silver halide emulsions and the polarographic oxidation half-wave potential and ring element half-wave potential.

For example, R.V. Berriman (R, V, Ber
riman) and P.B. Gilman Jr.
, B, GiIman Jr), Photographic Science and Engineering (Photo
graphicScience and Engine
If the oxidation half-wave potential of the dye becomes less than +0.40 V, photobleaching of surface fog is inhibited due to the capture of holes in the dye, as described in J. E. Ring, 17, 235-244 (1973).

Therefore, in order to spectrally sensitize the fogged direct positive silver halide emulsion of the present invention, the oxidation half-wave potential must be +
〇, a dye that is more positive than 40V is required.

The anionic cyanine dye used in the present invention is preferably represented by the following general formula (I).

In the formula, both AR1 and R2 are sulfoalkyl groups (for example,
γ-sulfopropyl, δ-sulfobutyl, etc.) or carboxyalkyl groups (such as β-carboxyethyl, γ-
carboxypropyl, etc.).

R4 represents a hydrogen atom, an alkyl group (eg, methyl, ethyl, etc.) or an aryl group (eg, phenyl group, etc.).

M represents an alkali metal atom (eg, sodium, potassium, etc.) or an ammonium group.

Zl and A2 represent a nonmetallic atomic group necessary to complete a 5- or 6-membered nitrogen-containing heterocyclic nucleus, and specific examples thereof include benzoxazole nuclei (e.g., benzoxazole, 5-methoxybenzoxazole, 6 2 ~quinoline nucleus (e.g. 2-quinoline, 3-methyl-2-quinoline, 5-methyl-2-quinoline, 7-methyl-2-quinoline, 8-methyl-2-quinoline, 6-
Chloro-2-quinoline, 8-chloro-2-quinoline, 6
-Medoxy-2-quinoline, 6-nitoxy-2-quinoline, 6-hydroxy-2-quinoline, 8-hydroxy-
2-quinoline etc.), 4-quinoline nucleus (e.g. 4-quinoline, 6-medoxy 4-quinoline, 7-methyl-4-
quinoline, 8-methylquinoline, etc.) A1-isoquinoline nucleus (e.g. 1-isoquinoline, 3,4-dihydro-1
-inquinoline etc.), 3-inquinoline nucleus (e.g. 3-inquinoline etc.), 3-inquinoline nucleus (e.g.
-inquinoline, 5-methyl-3-inquinoline, 1-
methyl-3-isoquinoline, 6-chloro-3-isoquinoline, 6-medoxy-3-inquinoline, 8-methoxy-3-inquinoline, etc.), indolenine nuclei (e.g.
, 3-dimethylindolenine, 3,3.5-trimethylindolenine A3, 3.7-1-dimethylindolenine, 5-hydroxy-3,3-dimethylindolenine, 6
-chloro-3,3-dimethylindolenine, 3,3-dibutyl-5-nitroindolenine, etc.), imidazoC4,
5-b) Quinoxaline nucleus (e.g. 1-ethylimidazo[4°5-b, lquinoxaline, ■-ethyl-6-nitroimidazo[4,5-b) quinoxaline, 1-phenylimidazo[4,5-b ] Quinoxaline, 6-chloro-1
-diphenylimidazo[4,5-b]quinoxaline, 1
-allylimidazo[4,5-b]quinoxaline, etc.)2
- naphthyridine (1,8) nucleus (e.g. 1,8-naphthyridine, 4-methyl-1,8-naphthyridine, 6-methyl-1,8-naphthyridine, 7-methyl-1,8-naphthyridine, etc.), 4 - naphthyridine (1,8) nucleus (e.g. 1,8-naphthyridine, 2-methyl-1,8-naphthyridine, 5-methyl-1,8-naphthyridine, 6-methyl-1,8-naphthyridine, 2,7 -dimethyl 1,8-
naphthyridine, etc.), oxazolo[4°5-b]pyridine nuclei (e.g., oxazolo[4°5-b]pyridine, 5-
Methyloxazolo[4゜5-bI pyridine, 6-nitrooxazolo[4゜5-b]pyridine, etc.), thiazolo[4
,5-b]pyridine nucleus (for example, thiazolo(4,5-b)
) pyridine, 5-methylthiazolo[4,5-b]pyridine, 6-nitrothiazolo[4,5-b]pyridine, etc.),
3-pyrrolo[2,3-b,l pyridine nucleus (e.g. 3,
3-dimethylpyrrolo[2,3-b)pyridine, 5-nitro-3,3-dimethylpyrrolo[2,3-b]pyridine, etc.), imidazo[↓, 5-bll pyridine nucleus, e.g. 1-
ethylimidazo[4,5-b]pyrazine, 1-phenylimidazo[4,5-b]pyrazine, 1-allylimidazo[4,5-b]pyrazine, etc.).

n, m. p represents O or 1.

Among the anionic cyanine dyes used in the present invention, more preferable ones are represented by the following general formulas (I) and (I).

In the formula, R4 and R5 both represent a sulfoalkyl group or a carboxyalkyl group as shown by R1 and R2 in general formula (I), and R6 represents a nitro group, a halogen atom, or a hydrogen atom.

Ml represents an alkali metal atom or an ammonium group.

Z3 represents a nonmetallic atomic group necessary to complete a 5- or 6-membered nitrogen-containing heterocyclic nucleus, and specific examples thereof include benzothiazole nucleus, 2-quinoline nucleus, 4-quinoline nucleus, indolenine nucleus, - Naphthyridine (1,8) nucleus, naphthyridine (1,8) nucleus, etc.

p1 represents O or 1.

In the formula, R7 represents a sulfoalkyl group or a carboxyalkyl group, R6 represents a nitro group, a halogen atom or a hydrogen atom, and R9 represents an alkyl group.

M2 represents an alkali metal atom or an ammonium group.

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

The halogen composition of the silver halide emulsion used in the present invention preferably contains 70 mol % or more of bromide.

In order to obtain even higher sensitivity, silver iodobromide or silver chloroiodobromide emulsions containing 95 mol % or more of bromide are preferred.

The silver halide emulsion used in the present invention includes both monodisperse and non-monodisperse emulsions, but monodisperse emulsions are more preferred.

The crystal habit of the silver halide emulsion used in the present invention is
It may be cubic or octahedral, but cubic is more preferable.

The silver halide emulsion grains used in the present invention may be regular or irregular.
lar), but regular ones are preferred.

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.

A method for making this type of emulsion is described, for example, in U.S. Pat. No. 3,367.
No. 778, No. 3,632,340, No. 3,709
, No. 689.

The silver halide emulsion used in the present invention is fogged by light or a chemical fogging agent.

For example, the method of chemically imparting fog includes the method described by Antoine Hautot3 and
Henri Sauvenier
) by Science et Industries Photographic (Science et Industries
Photograph-igue) 28, 57-65 (
Favorable results are obtained using the method of chemical sensitization described in (1957).

The silver halide emulsion used in the present invention is fogged by the reducing agent.

Examples of the reducing agent include stannous chloride, thiourea dioxide, formalin, alkali aruzenite, hydrazine derivatives, and amineborane.

The silver halide emulsion used in the present invention is also fogged by gold compounds.

Specific examples of gold compounds include chloroauric acid, potassium chloroaurate, and potassium thiosulfate.

The silver halide emulsion used in the present invention can also be used in combination with a reducing agent and a metal compound with a more noble potential than silver.
fog is given.

Specific examples of metal compounds having a more noble potential than silver include gold compounds such as potassium chloroaurate, platinum compounds such as potassium chloroplatinate, and iridium compounds such as potassium hexachloroiridate.

Furthermore, the silver halide emulsion can be fogged by combining the above method with a sensitizer such as sodium thiosulfate or allylthiourea, or a thiocyanic acid compound such as potassium thiocyanate.

In the present invention, it is preferable to include a known organic desensitizing dye in the silver halide emulsion in addition to an anionic cyanine dye in which the sum of the polarographic oxidation half-wave potential and reduction half-wave potential is positive. You can get results.

These organic desensitizing dyes have an electron-accepting property that captures free electrons, and the oxidation half-wave potential of a polarograph is 1.
It is more positive than OV and has a reduction half-wave potential of -1, which is greater than OV.

Specific examples of desensitizing dyes used in the present invention include pinacryptol yellow, phenosafranin, menalen blue, pinacryptol green, 3-ethyl-5m-
Nitrobenzylidene rhodanine, 3,3'-diethyl-
Examples include 6,6'-dinitrothiacarbocyanine iodide.

The protective colloid used in the present invention is generally gelatin, but modified gelatin such as phthalated gelatin,
Hydrophilic polymers such as polyvinyl alcohol and polyvinylpyrrolidone can also be used.

Moreover, a mixture of gelatin and a hydrophilic polymer can also be used.

In the present invention, polyethylene glycol and its derivatives are used as contrast enhancing agents, for example, Japanese Patent Publication Nos. 42-25201, 46-43437 and 46-2198.
Compounds described in No. 7 and the like can be added.

In addition, in the present invention, various additives such as stabilizers, brighteners, ultraviolet absorbers, hardeners, surfactants, preservatives, plasticizers, and matting agents may be included in the silver halide emulsion. can.

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 direct-positive silver halide photographic light-sensitive material of the present invention is obtained by coating the above-mentioned direct-positive silver halide emulsion on these supports, and if necessary, an overlayer is formed by a known method. It is also possible to provide one.

After exposure, the direct positive silver halide photographic light-sensitive material of the present invention is processed with an alkaline developer containing hydroquinone as a single developing agent.

A known lithium-type developer is used as this developer.

Further, the direct positive silver halide photographic light-sensitive material of the present invention is processed using known processing baths such as fixing and bleaching baths, or a combination of these processing baths.

The first feature of the present invention is that it is possible to obtain a direct positive silver halide photographic light-sensitive material that provides high contrast images and provides good quality line images and halftone images (halftone images).

The second feature of the present invention is that a lithium-type direct positive silver halide photographic light-sensitive material can be obtained which can reproduce a positive image from a positive original or a negative image from a negative original with a single development process. At the point.

The third feature of the present invention is that a highly sensitive lithium-type direct positive silver halide photographic material can be obtained.

Hereinafter, the present invention will be explained in detail based on Examples, but of course the present invention is not limited thereto.

Example 1 An emulsion was prepared according to the following formulation.

■ Keep the acetic acid ■ solution at 40℃, add the ■ solution while stirring vigorously, and add 1
After 1 minute, Solution M was added and the mixture was aged at 40° C. for 9 minutes, and then Solution 2 was added to adjust the pH to 3.0.

An aqueous sodium sulfate solution was added to this to precipitate it, which was washed with water.

This raw emulsion was a silver chloroiodobromide emulsion with an average grain size of 0.45 μm, a crystal habit mainly cubic, and a bromide content of 95 mol % or more.

(Raw emulsion A). Raw emulsion A was redissolved, gelatin was added, and an aqueous potassium iodide solution corresponding to 1 mol% per mol of silver halide was added to adjust the pH to 6.5 and pAg to 6.2.
After adding thiourea dioxide equivalent to 0.1 mg per mol of silver halide and aging at 60°C for 60 minutes, add potassium chloroaurate equivalent to 2 g per mol of silver halide. was added and further aged at 60°C for 60 minutes.

After this, the pH was adjusted to 5.0 and the pAg to 8.0.

This was divided into four equal parts and a sensitizing dye was added according to the recipe in Table 1.

For comparison, a dye with the following structural formula was used.

140mg of Pinacryptol Yellow in each emulsion
/mole Add Ag, hardener and surfactant,
It was applied to a polyethylene terephthalate film provided with a subbing layer and dried.

The amount of silver coated was 2.6 g/m'.

Each sample thus prepared was cut into appropriate sizes, exposed through a wedge with a density difference of 0.15, and then developed for 6 minutes at 20° C. with developer D-85 having the composition shown below.

Water (approximately 30°G) 500ml Anhydrous sodium sulfite 30g Paraformaldehyde 7.5g Sodium acid sulfite
2.2g boric acid
7.5g Hydroquinone 22.5
g Potassium bromide 1.6g Add water to 10100O After this, stop.
It was fixed, washed with water, and then dried.

Table 1 shows the characteristic values obtained as a result of concentration measurement.

DmaxDmin represent the maximum optical density and minimum optical density, respectively, sensitivity S represents the relative value of the reciprocal of the exposure amount required to give a density of 1.0, and 7 represents the relative value of the reciprocal of the exposure amount required to give a density of 1.0. The slope was shown.

As is clear from Table 1, cationic dye (1a)
, inner salt type dye (1b), anionic type dye (1)
In Lith development, the sensitization efficiency is almost the same, but (la
) and (lb), the anionic type (1) exhibits extremely high-contrast photographic characteristics and exhibits a so-called development effect.

The direct positive silver halide photographic light-sensitive material according to the present invention includes:
In this way, it has high contrast photographic characteristics,
A good positive halftone image can be obtained by passing a positive original through a screen, exposing it to halftone dots, and performing lithographic development.

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

■ Keeping the 6N sulfuric acid ■ solution at 60°C, add the ■ solution and ■ solution at the same time over 80 minutes while stirring strongly, and the pAg during this time was 7.
Controlled to 5.

Thereafter, solution (2) was added to make p)l=3.5 to precipitate, and the mixture was washed with water.

This raw emulsion is a silver iodobromide emulsion containing 97.5 mol% of bromide, and has an average grain size of 0.25μ, with cubic monomers containing 95% by weight or more of grains within ±20% of the average size. It is a dispersed emulsion.

(Raw emulsion B).

This raw emulsion B was redissolved, gelatin was added, and pH = 6.
．． 5pHg was adjusted to 6.2.

Add thiourea dioxide 0.2 mg/mole Ag,
After aging at 65°C for 45 minutes, chloroauric acid 2mg/moleA
g was added thereto, and the mixture was further aged for 45 minutes at 65°C.

Thereafter, the pH was adjusted to 5.0 and the pAg to 8.0, and the mixture was divided into 12 equal parts and a sensitizing dye was added according to the recipe shown in Table 2.

For comparison, a dye with the following structural formula was used.

Pinacryptol yellow 140mn in each emulsion
g/mole Ag was added, a hardening agent and a surfactant were added, and the mixture was coated on a cellulose triacetate film provided with an undercoat layer and dried.

The amount of silver coated was 3.4 y/m2.

Each sample thus prepared was cut into appropriate sizes, exposed through a wedge with a density difference of 0.15, and then developed with developer D-85 of Example 1 at 20°C for 6 minutes. .

After that, it was stopped, fixed, washed with water, and then dried.

Table 2 shows the characteristic values obtained as a result of concentration measurement.

As is clear from Table 2, the direct positive silver halide photographic light-sensitive material of the present invention has high contrast photographic properties as seen in samples t and IIn+q.

Therefore, this direct positive silver halide light-sensitive material is suitable as a lithium-type photographic light-sensitive material.

Example 3 An emulsion was prepared according to the following formulation.

xl Keep the 6N sulfuric acid ■ solution at 40°C, add solution X while stirring strongly,
After 1 minute, Solution M was added, and the mixture was aged at 40° C. for 9 minutes, and then Solution 2 was added to adjust the pH to 3.0.

To this, an aqueous solution of sodium sulfate was added to precipitate the mixture, which was then washed with water.

This raw emulsion was a silver chloroiodobromide emulsion with an average grain size of 0.4 .mu.m, a crystal habit mainly cubic, and containing about 75% bromide.

(Raw emulsion C). Original emulsion C was redissolved, gelatin was added, and an aqueous potassium iodide solution corresponding to 0.5 mol% per mol of silver halide was added to adjust the pH to 6.5 and pAg to 6.
．． Adjusted to 0, thiourea dioxide 0.1 mg/mole
Ag and potassium chloroaurate (2 mg/mole Ag) were added, and the mixture was aged at 60° C. for 75 minutes.

Thereafter, the pH was adjusted to 5.0 and the pAg was adjusted to 8.0.

This was divided into four equal parts, and a sensitizing dye was added according to the recipe in Table 3.

Pinacryptol Yellow 300mg/in each emulsion
Mole Ag was added, a hardening agent and a surfactant were added, and the mixture was applied onto a cellulose triacetate film provided with a subbing layer and dried.

The amount of silver coated is 4. It was Or/m2. Each sample prepared in this way was cut into appropriate sizes, and the samples were cut into pieces with a concentration difference of 0.
．． After exposure through a No. 15 wedge, development was performed using the developer D-85 of Example 1 at 20° C. for 6 minutes.

After that, it was stopped, fixed, washed with water, and then dried.

Table 3 shows the characteristic values obtained as a result of concentration measurement.

As is clear from Table 3, the direct positive silver halide photographic material according to the present invention has high contrast photographic properties and is suitable as a lithographic photographic material.

Example 4 Raw emulsion A was prepared in the same manner as in Example 1, and after redissolving,
Add gelatin, add potassium iodide aqueous solution equivalent to 1 mol% per mol of silver halide, and adjust the pH to 6.5.
Adjust the pAg to 5.0 and add chloroauric acid 2Rg/mole.
Ag was added and aged at 60°C for 90 minutes.

Thereafter, the pH was adjusted to 5.0 and the pAg to 8.0. After dividing this into three equal parts, a sensitizing dye was added according to the recipe in Table 4.

Each emulsion contains pinacryptol i: o-200/m
g/mole Ag was added, a hardening agent and a surfactant were added, and the mixture was coated on a polyethylene terephthalate film and dried.

The amount of silver coated was 3.4 f/m2.

After cutting each of the samples thus created into appropriate sizes and exposing them to light through a 0.15 density difference wedge,
Development was performed using the developer D-85 of Example 1 at 20° C. for 6 minutes.

After that, it was stopped, fixed, washed with water, and then dried.

Table 4 shows the characteristic values obtained as a result of concentration measurement.

As is clear from Table 4, the direct positive silver halide photographic material according to the present invention has high contrast photographic properties and is suitable for a lithographic photographic material.

Claims (1)

[Scope of Claims] 1. A silver halide photographic material to be processed with an alkaline developer containing hydroquinone as a single developing agent, wherein the silver halide emulsion is a silver halide emulsion containing 70 mol% or more of bromide. a fogged direct-positive silver halide photographic light-sensitive material containing at least one anionic cyanine dye whose polarographic half-wave potential is more positive than +〇, 40 V in the silver halide emulsion. . 2. The direct positive silver halide photographic material according to claim 1, wherein the silver halide emulsion is a silver chloroiodobromide emulsion containing 95 mol % or more of bromide. 3. The direct positive silver halide photographic light-sensitive material according to claim 1, wherein the silver halide emulsion is a silver iodobromide emulsion containing 95 mol % or more of bromide. 4. Claims 1 and 2 contain an organic desensitizing dye by adding an anionic cyanine dye whose half-wave polarographic oxidation potential is more positive than +0.40 V to the silver halide emulsion. 3. Direct positive silver halide photographic material according to item 1 or 3. 5. An anionic cyanine dye having a polarographic half-wave potential of more than 0.40 V has the following general formula (I) (wherein Zl and Z2 complete a 5- or 6-membered nitrogen-containing heterocyclic nucleus). Represents a necessary nonmetallic atom group, R1 and R2 both represent a sulfoalkyl group or a carboxyalkyl group, R3 represents a hydrogen atom, an alkyl group, or an aryl group, and M represents an alkali metal atom or , represents an ammonium group; n, n+p represents 0 or 1.) The silver halide photographic material for direct positive use according to claim 1 or 4, which is a dye represented by: 6) The cyanine dye of the following general formula (I) (wherein z3 represents a nonmetallic atomic group necessary to complete a 5- or 6-membered nitrogen-containing heterocyclic nucleus, and R4, R, , both represent a sulfoalkyl group or a carboxyalkyl group, and R
6 represents a nitro group, a halogen atom or a hydrogen atom, M
1 represents an alkali metal atom or an ammonium group. p1 represents O or 1. ) The silver halide photographic material for direct positive use according to claim 5, which is a dye represented by: 1. The cyanine dye of the general formula (I) has the following general formula (■) (wherein R, 7 represents a sulfoalkyl group or a carboxyalkyl group, R8 represents a nitro group, a halogen atom or a hydrogen atom, and R, 6. The direct positive silver halide photographic light-sensitive material according to claim 5, which is a dye represented by the following formula: M2 represents an alkyl group, and M2 represents an alkali metal atom or an ammonium group.