JPH02195342A - Direct positive silver halide photographic sensitive material - Google Patents

Abstract

PURPOSE:To enhance sensitivity, to reduce fog, and to improve contrast in the low density range by incorporating silver halide grains prepared by regulating pAg to >=9.7 in at least one of direct positive silver halide emulsion layers in the later half of emulsion preparation step. CONSTITUTION:At least one of the direct positive silver halide emulsion layers contains the silver halide grains prepared by regulating pAg to >=9.7 in the later half of the preparation step, after the point of time when half the material silver to be used for preparing the emulsion has been consumed. It is preferred to instantaneously or gradually change the pAg when the produced or precipitated silver reaches half the total silver amount to be used for the emulsion preparation to regulate pAg to >=9.7 at the time of end of the preparation, thus permitting sensitivity to be enhanced to a prescribed degree, fog to be lowered, and the contrast in the range of low density to be improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a silver halide photographic material, and particularly to a direct positive silver halide light-sensitive material that has high sensitivity, low fog, and good contrast in low density areas. It is something.

[Conventional technology]

Normally, when a silver halide photographic light-sensitive material is exposed to light including light in the photosensitive range of the light-sensitive material and developed, the blackening density increases as the exposure amount increases, and reaches a maximum at a certain exposure amount. However, when the exposure amount is further increased, a phenomenon is observed in which the blackening density decreases. This phenomenon is called solarization. Therefore, if a silver halide photographic emulsion is optically or chemically given an appropriate amount of fog so that the blackening density reaches its maximum value, solarization occurs upon exposure, and a positive image can be directly obtained. As is well known, a light-sensitive material utilizing such a reversal phenomenon is called a direct reversal silver halide photographic light-sensitive material.

This type of direct reversal silver halide photographic light-sensitive material is used for copying various types of photographs, for example, for copying relatively continuous tone photographs such as X-ray photographs. In order to achieve this, it is particularly desirable to maintain a predetermined maximum density, have high sensitivity, little reversal fog, and have good contrast in low density areas.Therefore, the development of such photosensitive materials is required. has been done.

However, as a halide emulsion in conventional silver halide photographic materials of this type, silver halide grains having a wide grain size distribution have been used in many cases. For this reason, it cannot be said that all silver halide grains of all grain sizes have been chemically sensitized, and therefore the inherent sensitivity of each silver halide grain is not fully brought out. It wasn't.

Techniques for increasing the sensitivity of silver halide photographic materials are actively being developed. JP-A-52-153428, JP-A No. 54-1
No. 45827, No. 55-142329, and other publications describe the technique of using twinned silver halide grains, which was published in Japanese Patent Application Laid-open No. 58.
-12792, 58-95337, 58-10
No. 8526, No. 58-111937, No. 58-113
Patent Publications such as No. 928 describe techniques using tabular silver halide grains;
Publications No. 8235 and No. 58-49938, as well as Japanese Patent Application No. 58-53043 and No. 58-54949, etc.
Techniques using monodisperse emulsions have been described respectively.

In addition, as a technique for obtaining good contrast, for example,
Techniques include using discrete high contrast steps as described in U.S. Pat. No. 3,615,573.

However, with none of the above techniques, it has been impossible to obtain a silver halide photographic material with less fog, higher sensitivity, and particularly good contrast in low density areas.

[Purpose of the invention]

As described above, conventional direct positive silver halide photographic materials have the disadvantages of low sensitivity, high reversal fog, and poor contrast in low density areas. An object of the present invention is to provide a direct positive silver halide photographic light-sensitive material that has a predetermined sensitivity, low fog, and good contrast in low density areas.

[Structure of the invention]

The above-mentioned object of the present invention is to provide a direct-positive silver halide photographic light-sensitive material having at least one direct-positive silver halide emulsion layer on one side of the support. At least one of the layers contains silver halide grains obtained by adjusting pAg to 9.7 or more in the latter half of the preparation process (hereinafter also referred to as "silver halide grains according to the present invention"). This is achieved by a direct positive silver halide photographic light-sensitive material characterized by containing.

The present invention has been made as a result of intensive research by the present inventors to achieve the above object of the present invention, and it has been found that when silver halide grains are adjusted to have a pAg of 9.7 or more in the latter half of the preparation, fog is reduced and a higher It has been found that silver halide grains with good sensitivity and contrast, particularly in low density areas, can be obtained, and this study was carried out based on this knowledge.

In the present invention, the "second half of the fI preparation process" refers to the period after 1/2 of the raw material silver used for emulsion preparation is consumed in the emulsion preparation process.

When preparing the silver halide grains according to the present invention as described above, the amount of formed or precipitated silver is instantaneously or gradually reduced to 1/2 or more of the total amount of silver prepared.
It is best to vary the pAg so that the pAg at the end of preparation is 9.7 or more, and range from 2/3 to 9/lO of the total preparation amount.
At the point of time, the pAg was gradually changed to 9.7 at the end of the preparation.
It is more preferable that the above is the case.

The size distribution of the silver halide grains according to the present invention is arbitrary, and the emulsion containing the grains may be a monodisperse emulsion or a polydisperse emulsion, and according to the present invention, any emulsion is suitable. results. The monodisperse emulsion may be used alone or in combination of at least two types.

The silver halide grains according to the present invention may be contained in at least one direct positive silver halide emulsion layer in the light-sensitive material of the present invention, preferably contained in all emulsion layers. The proportion of silver halide grains according to the present invention contained in the core layer in the emulsion layer containing the silver halide grains according to the present invention may be arbitrarily selected, but is preferably 0 relative to all the silver halide grains in the layer. It is preferable that the silver content is 40% or more. Particularly preferably, it is 90% or more.

The composition of the silver halide grains according to the present invention may be any silver halide such as silver chloride, silver chloride, silver chlorobromide, silver bromide, silver iodobromide, and silver iodide. From this point of view, silver iodobromide is preferable. Furthermore, the average silver iodide content in silver iodobromide is preferably 0.1 to 10 mol%, particularly preferably 1 to 8 mol%.

In addition, in the present invention, in order to obtain a good positive image,
Any suitable electron trap can be used. This is effective in preventing reactions in which silver nuclei form and grow between photoelectrons and silver ions. As specific means, noble metal atoms or the like may be introduced as an inorganic desensitizer into the crystal interior of the silver halide grains, or an electron-capture desensitizing dye that is adsorbed on the crystal surface may be used.

When an inorganic desensitizer is used, a soluble metal salt of group (I), such as a soluble rhodium salt or a soluble iridium salt, may be added in order to incorporate the inorganic desensitizer into the silver halide grains. These soluble salts are preferably added in an amount of 10-1 to 10-8 mol, more preferably 10-' to 10-3 mol, per 1 mol of halide vA. It is desirable to add it inside.

For techniques using electron-capture desensitizing dyes, see
British Patent No. 1186717, British Patent No. 1186714,
It is described in US Pat. No. 1,186,716, US Pat. No. 1,520,817, US Pat. No. 3,501,306, US Pat.

The direct positive silver halide emulsion used in the present invention can be formed by imparting appropriate fog.

For example, fog can be imparted to a silver halide emulsion by using a reducing agent and a gold compound. In this case, at least one compound selected from thiosulfate and/or thiocyanate is allowed to coexist and then fogged, or after fogging is performed with a reducing agent and a gold compound, thiosulfate is Even better fogging can be imparted by containing at least one compound selected from thiocyanate and/or thiocyanate.

Regarding the direct positive silver halide emulsion used in the present invention,
By adding water-soluble iodide to the silver halide emulsion before fogging, good release can be obtained. Examples of water-soluble iodides include ammonium, potassium, lithium, and sodium iodides, and the amount added is preferably 1 water-soluble iodide per mol of silver halide.
~10 mmol. If the amount added is less than this, the removal may not be sufficient. If the amount is more than this, a sufficient maximum concentration may not be obtained or the concentration tends to decrease during storage.

The conditions for fogging silver halide can be varied over a wide range, but the pH is generally preferably within the range of 5.5 to 9.
More preferably the pH is in the range of 6 to 7. Also pAg
-M is preferably in the range of 6.5 to 8.5, and the temperature is generally preferably in the range of 40°C to too' C1, more preferably 50°C to 70°C.

A hydrophilic protective colloid such as gelatin that suspends the silver halide grains during fogging is
It is preferably used in a proportion of 30 to 200 grams per mole.

Reducing agents used to impart fog include aldehyde compounds such as formalin, organic reducing agents such as organic amine compounds such as hydrazine, triethylenetetramine, thiourea dioxide, and imino-amino-methanesulfinic acid, and dichloromethane. Inorganic reducing agents such as tin or reducing agents such as amine borane are preferably used.

The concentration of the reducing agent used varies depending on the silver halide grains, field of application, purpose, etc., and also varies depending on the type of reducing agent, but is generally 0.001 per mole of silver halide.
-1.00 mmol is preferred.

The gold compounds used to impart fogging are generally monovalent and trivalent soluble gold salts, such as chloroauric acid, gold thiocyanate, sodium chlorate, potassium chlorate, potassium bromine, and iodine. Potassium acid, potassium gold cyanide, potassium gold thiocyanide, sodium gold thiomaleate, gold thioglucose, etc. are used.

The amount of gold compound used depends on the size, composition, and
Although it varies depending on the purpose of application, it is generally preferably within the range of 0.0001 to 0.1 mmol, more preferably 0.005 to 0.1 mmol per mole of halogenated molecule.
Good results are obtained when used at low concentrations, in the range of 0.05 mmol.

When thiosulfate or thiocyanate is used for fogging, specific examples include sodium thiosulfate, ammonium thiosulfate, potassium thiocyanate,
Ammonium thiocyanate or complex salts thereof are preferably used, and these compounds generally contain silver halide 1
It is preferably used in a range of 0.0003 to 10.0 mmol per mole, more preferably o, oos to 0
．． Used at 5 mmol. These thiosulfate and thiocyanate salts may be used before fogging with the reducing agent and gold, during fogging, or after fogging, but the required amount will vary depending on the time of use. Increasing amounts are generally required, especially when added after fog formation.

Various other photographic additives can be added to the direct positive silver halide emulsion used in the present invention.

As a stabilizer, for example, Japanese Patent Publication No. 49-16053, No. 49
-12651, those described in JP-A-48-66828, etc., or triazoles, azaindenes,
A quaternary benzothiazolium compound, a mercapto compound, or a water-soluble inorganic salt such as cadmium, cobalt, zinc, manganese, or zinc may be included, and as a hardening agent, for example, an aldehyde such as formalin, glyoxal, mucochloric acid, etc. s-triazines, epoxies, aziridines, vinyl sulfonic acid, etc., and coating aids such as saponin, sodium polyalkylene sulfonate, lauryl or oleyl monoether of polyethylene glycol, aminated alkyl taurine, JP-A-Sho 49-
Fluorine-containing compounds selected from those described in Japanese Patent Publication No. 10722, Japanese Patent Publication No. 49-46733, etc., and sensitizers such as Japanese Patent Publications No. 42-25203, Japanese Patent Publication No. 43-10245,
No. 43-13822, No. 43-17926, No. 43
-17927, 46-21186, 49-81
Polyalkylene oxides selected from those described in No. 02, No. 49-8332, and derivatives thereof may also be contained. Furthermore, it is also possible to contain a color coupler selected from those described in, for example, Japanese Patent Publication Nos. 45-24910 and 45-29878. In addition, brighteners, thickeners, preservatives, capping agents, antistatic agents, etc. can also be contained as necessary.

The silver halide emulsion used in the present invention includes protective colloids such as gelatin, gelatin derivatives, and natural substances such as albumin, agar, gum arabic, and algin 11.
Furthermore, polyvinyl alcohol, polyvinyl acrylate,
Polyvinylpyrrolidone, cellulose ethers, partially hydrolyzed cellulose acetate, Japanese Patent Publication No. 49-20530
Poly(N) grafted with ethylene oxide described in the issue
Hydrophilic polymers such as -hydroxylalkyl) β-alanine derivatives can be included. Furthermore, a dispersion-polymerized vinyl compound may also be contained as a binder for emulsion. For example, a polymer latex of an unsaturated ethylenic monomer emulsion-polymerized in the presence of an activator as described in Japanese Patent Publication No. 49-32344, Japanese Patent Publication No. 19-20964. The second listed in
It is preferable to use a cerium salt to contain a polymer latex or the like in which a polymer compound having a hydroxyl group is grafted with an unsaturated ethylenic monomer from the viewpoint of improving the physical properties of the film.

Also, from the emulsion technology, Japanese Patent Publication No. 44-2523, No. 44
As described in No. 9499, the developer is protected and contained, higher fatty acids such as liquid paraffin and higher unsaturated fatty acids such as stearyl acetoglyceride are protected and contained to improve film properties, and color couplers are added depending on the purpose. It is also possible to protect and contain stabilizers and the like.

The direct positive silver halide emulsion thus obtained is
Any suitable photographic support such as glass, wood, metal,
Films, such as cellulose acetate, cellulose acetate butyrate, cellulose nitrate, polyester, polyamide, polystyrene, etc., are coated on paper, baryta-coated paper, polyolefin-coated paper, such as polyethylene- or polypropylene-coated paper, to form a photosensitive material. Ru. Polyolefin coated paper can be made to have good emulsion adhesion by electron impact treatment.

The direct positive silver halide photosensitive material constructed in this manner maintains a predetermined sensitivity, has little reversal fog, and has good contrast particularly in low density areas.

〔Example〕

The present invention will be explained in more detail below by showing examples of the present invention. However, as a matter of course, the present invention is not limited to the examples described below.

The compounds used in each of the following examples are as follows.

Compound (A) Compound (B) Compound (1) L water 210ml/AgX1-1-
J.L.

Compound (n) C1lICj! - Compound (1) Example-1 A monodisperse emulsion was prepared according to the following formulation. In the following description, AgX represents silver halide.

(d) Neutralize to acetic acid piis, o First, at 40°C, 1/10 of solution (a) and solution (b) were simultaneously placed in a reaction vessel for emulsion preparation with propeller type stirring at a rotation speed of 300 rpm. The mixture was added over a period of 15 minutes while stirring in a vessel. Then (
A) 9/lO of the liquid and (c) the liquid by the double jet method,
It was added while controlling the flow rate. In this case, as shown in FIG. 1, silver halide grains are prepared at pH=9.7 and pAg is adjusted according to the patterns of ■ to [phase] in the same figure.
Each emulsion for samples 2 to 11 shown in Table 1 below was obtained.

The above is the particle forming step, and then a desalting step is started in which excess salt is removed.

That is, the silver halide emulsion obtained in the above step was kept at 40°C, and the compound (A) was added at 5 g/AgXI-t-ru,
and MgSO4 were added at 8 g/A g X l:e, stirred for 5 minutes, and then left to stand. Thereafter, the supernatant liquid was discharged to give a liquid volume of 20 Qcc per mole of silver halide. Next, 1.81/AgX1 mole of pure water at 40°C was added, and the mixture was stirred for 5 minutes.

Next, 20 g/AgX 1 mol of Mg5Oa was added, stirred and left to stand in the same manner as above, and the supernatant liquid was removed to perform desalting.

This solution was then stirred.

After stirring, post-gelatin was added to disperse the silver halide again, and the mixture was dispersed at 55°C.

After adjusting the pH of these emulsions to 6.8, an appropriate amount of potassium iodide was added to each emulsion. Thereafter, at 60° C., 0.5 μm of thiourea dioxide/1 mol of AgX, 2.1 μm of sodium thiosulfate/1 mol of Ag It has matured until it is finished. A spreading agent and a hardening agent were added to each matured emulsion, and glycidyl methacrylate 50-t
A copolymer aqueous dispersion obtained by diluting a copolymer consisting of three monomers, 10 wt% (%, methyl acrylate), and 40 wt% butyl methacrylate, to a concentration of 10 wt% was prepared below. A sample was prepared by coating on a polyester film base coated as a draw liquid at a weight of tB of 14 g per liter and drying. The samples obtained in this way were each exposed to light using a sensitometric light model, and developed for 90 seconds with NewXD-90 developer and NewXF fixer using a KX-500 automatic processor manufactured by Konica Corporation. The fog and sensitivity of each sample were determined, and the contrast in low density areas was evaluated. The results are shown in Table 1. The sensitivity was calculated as the reciprocal of the amount of light required for the blackening density to increase by 1.0 due to exposure, and expressed as a relative value with the sensitivity of sample light 2 as 100. In addition, the obtained samples were visually compared with respect to the contrast of the low density area, and the difference in contrast was evaluated and displayed on a five-point scale from 1 < excellent to 5 ( poor ).

As is clear from Table 1, all the samples according to the present invention had excellent performance in terms of sensitivity, reverse fog, and contrast in low density areas.

Example-2 A monodisperse emulsion was prepared according to the following formulation.

(d) Acetic acid Amount to neutralize to pH 6.0 First,
At 40°C, 1/10 of solution (a) and solution (a) were added to a reaction vessel for emulsion preparation over 15 minutes while stirring with a propeller type stirrer with a rotational speed of 300 revolutions/min. Then ( A) 9/10 of the liquid and (c) the liquid were added using the double jet method while controlling the flow rate.In this case, as shown in Figure 1, the pH was 9.7, and the pAg was Silver halide grains were prepared by adjusting according to the pattern of [Phase].Desalting and fogging were carried out in the same manner as in Example-1.

By adjusting the pAg, each emulsion for sample fish 12 to 1 klB shown in Table 2 below was obtained. pAg! ! The regular patterns are also shown in Table 2. Further, the emulsion was coated and dried in the same manner as in Example 1, and was tested and evaluated in the same manner. However, the sensitivity was expressed as a relative value with the sensitivity of sample patient 12 in Table 2 as 100.

As is clear from Table 2, similar to Example 1, the sample according to the present invention had excellent performance in both sensitivity reversal fog and contrast in low density areas.

Example-3 A monodispersed emulsion was prepared according to the following formulation.

(h) Acetic acid Amount to neutralize to pif6.0 First, at 40°C, 1/10 of solution (e) and solution (f) were simultaneously placed in a reaction vessel for emulsion preparation, using propeller type stirring at a rotation speed of 300 rpm. It was added over 15 minutes while stirring with a container (Step-1)
). Next, 9/10 of the solution (e) and the solution (g) were added by a double jet method while controlling the flow rate. in this case,
As shown in Figure 1, pAg was adjusted at pH 9.7 according to the patterns from ■ to [phase] shown in the diagram (Step-2).
.

After adjusting the pH of the obtained emulsion to 6.8,
An appropriate amount of potassium iodide was added (Step-6).

At 60°C, thiourea dioxide 0.5 μ/AgX 1 mol, sodium thiosulfate 2.1 mg/A g Aged until obtained (Step-7)
.

In the examples, the compound (1) is added in the emulsion grain forming step and the desalting step, that is, steps 1 to 5 (and thereafter, before the post-gelatin addition and fogging step) to obtain an emulsion. In order to observe changes in photographic performance depending on the addition position, samples were prepared by adding compound (1) at different times. That is, in the above-mentioned steps, compound (1) was added at the end of each step to prepare an emulsion, thereby obtaining each emulsion for samples N1119 to Magnetic 45 shown in Table 3 below. Table 3 also shows the step number, type, amount, etc. indicating the addition position of compound (1).

Also, for compounds (n) and (m), the above steps -
An emulsion was prepared by adding it to the emulsion prepared up to 7 in the same manner, and using this emulsion, sample fish 46 to 51 were obtained. These are also shown in Table-3.

After adjusting the pH of these emulsions to 6.8, an appropriate amount of potassium iodide was added to each emulsion. Thereafter, at 60°C, thiourea dioxide 0.5we/AgX1 mol, sodium thiosulfate 2.1■/AgX1 mol, and chloroauric acid 2
．． 7 .mu./1 mol of AgX was added, and the mixture was aged until a proper fog was obtained. A spreading agent and a hardening agent were added to each ripened emulsion to form a copolymer consisting of three monomers: 50 wt% glycidyl methacrylate, 10 wt% methyl acrylate, and 40 wt% butyl methacrylate, to a concentration of 10 wt%. Copolymer aqueous dispersion obtained by diluting it to -t% and coating it on a polyester film base coated as an undercoat liquid at a concentration of 4 g of silver per lnf,
It was dried and a sample was prepared. The samples obtained in this way were each exposed to light using a sensitometric light wedge, and then processed using NewXD-90 developer and NewXF fixer at a 90%
A second development process was performed, and the fog and sensitivity of each sample were determined, and the contrast in low density areas was evaluated.

The results are shown in Table-3. The sensitivity is such that the blackening density is 1. The reciprocal of the amount of light required to increase by O was determined and expressed as a relative value with the sensitivity of sample 19 as 100. Also,
The obtained samples were visually compared with respect to the contrast in the low density area, and the difference in contrast was evaluated and displayed on a five-point scale from 1 (excellent) to 5 (poor).

As is clear from Table 3, in this example, as in Example 1.2, the sample according to the present invention had excellent performance in terms of sensitivity, reverse fog, and contrast in low-density areas. .

〔Effect of the invention〕

As described above, according to the present invention, it was possible to provide a direct positive silver halide photographic light-sensitive material that has high sensitivity, little reversal fog, and good contrast especially in low density areas.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a pAg pattern in an example. ■~0... pAg pattern.

Claims (1)

[Claims] 1. In a direct positive silver halide photographic light-sensitive material having at least one direct positive silver halide emulsion layer on at least one surface of the support, at least one of the direct positive silver halide emulsion layers is A direct-positive silver halide photographic light-sensitive material comprising silver halide grains obtained by adjusting pAg to 9.7 or more in the latter half of the preparation process.