GB2060189A - A method to form a negative image - Google Patents

Abstract

In the photographic processing of a light-sensitive silver halide material of a kind containing substantially non- light-sensitive metallic salt grains and development nuclei, the processing liquid contains a compound of formula <IMAGE> (in the formula, X, Y and Z respectively represent a nitrogen atom or CR group (R represents a hydrogen atom, or a lower alkyl or aryl group), R1 and R2 respectively represent a hydrogen or halogen atom, or a lower alkyl, lower alkoxy, aryloxy, NO, NO2, CN, COR3, SO2R4, OH, or <IMAGE> group (R3 and R4 respectively represent a hydrogen atom, or a lower alkoxy, OH, lower alkyl, aryl, aryloxy or OH group, R5 and R6 respectively represent a hydrogen atom, or a lower alkyl or aryl group).

Description

SPECIFICATION A method to form a negative image This present invention relates to a method to form a negative image, and particularly to an image forming method that a negative image having high sensitivity, high contrast and high maximum density is obtainable by making use of light-sensitive silver halide, metallic salt and nuclei for physical development.

Silver, that is indispensable to silver halide photographic material, of which the supply is on the decrease while the demand is on the increase and consequently the price is on the remarkable rise, and for this, it is the existing state of things that new ventures to economize silver are being attempted actively.

For example, there is the silver salt diffusion transfer process utilizing with nuclei for physical development. The process is well known as a very useful image forming process, because of the facts that a photographic image having higher density can be obtained by using with a small quantity of silver halide due to the high covering power of transferred images, and that the sensitivity and sharpness are both superior.

However, the process is a negative-positive type diffusion transfer process and the final image is a positive image, therefore, it is not suitable to the method and purpose of the present invention that a negative image is to be formed.

On the other hand, according to Japanese Patent L--OO-P publication No. 54-48544, a kind of light-sensitive material, which obtains a negative image ultimately by a silver salt diffusion transfer process, was so proposed therein as having light-sensitive silver halide, physical development nuclei and metallic salt grains adsorbed by a substance which makes the grains less soluble, which grains are per se more soluble than the light-sensitive silver halide and do not have sensitivity substantially. The material is processed by the processing liquid containing reducing agent and a substance that solves the metallic grain. However it is necessary for a long time developing process. Therefore, a rapid processing that is desirous nowadays is impossible to do.Further, because the efficiency of the said processing is strikingly inferior, losses of sensitivity and density are caused and economization of silver is inevitably impossible. Furthermore, the addition into light-sensitive material with dissolution inhibiting agent having enough quantity to enable to inhibit dissolving of silver halide particles causes various defects such as that deensitization of light-sensitive material is caused during storage for long time as a matter of course.

It is the first object of the invention to provide a silver halide photographic material that obtains a negative image having high sensitivity, high contrast and high maximum density with silver-saved lightsensitive photographic element, and it is the second object of the invention to provide an image forming method having comparatively low fog and high contrast.

In the present invention a photographic material which comprises (1) a light-sensitive silver halide, (2) metallic salt grains which are per se more soluble in a processing liquid containing a solvent than the light-sensitive silver halide and are substantially non-light-sensitive, and (3) nuclei for physical development is, after imagewise exposure, processed by the processing liquid which contains a reducing agent and the solvent to dissolve the metallic salt grains in the presence of a compound represented by the following formula::

[Wherein X, Y and Z individually represent a nitrogen atom or CR radical (R represents a hydrogen atom or a lower alkyl or aryl radical), R1 and R2 each represents a hydrogen or halogen atom, or a lower alkyl, lower alkoxy, aryloxy, NO, NO2, CN, COR3, SO2R4, hydroxyl, aryl or

radical (wherein R3 and R4 each represent a hydrogen atom, or a lower alkoxy, hydroxy, lower alkyl, aryl or aryloxy radical, and R5 and R6 each represent a hydrogen atom, or a lower alkyl or aryl radical)j.

The compounds shown in the above general formula are used within a range of 0.01 g - 10 g to 11 of a processing solution for development or 10-3 to 10-5 mol/mol of metal salt grain, and water or water soluble organic solvent, for example, methanol and so on, is used as a solvent in adding the compound.

Concretely typical examples of compounds represented by the formula [I] are as follows:

These compounds are quite simple and well known. They can be easily synthesized.

The present invention is described in further detail as follows: The light-sensitive silver halide is silver chloride, silver bromide, silver iodide, silver chloro-bromide silver iodo-bromide, silver iodo-chloro-bromide or their mixture etc., and high sensitive silver iodobromide is preferably used, particularly silver iodo-bromide containing silver iodide of 50 mol% or less is suitable. And photographic emulsion containing silver halide for use in the invention is prepared by a method conventionally being used. And the silver halide having various crystal habits is useful.

The silver halide emulsion can be sensitized by making use of various types of sensitizer, and can be spectrally sensitized with a sensitizing dye, and it may contain various types of stabilizing agent.

Metallic salt grain per se is dissolved in a processing liquid containing a dissolving substance mentioned later faster more than 5 times, preferably 10 times up to 10,000 times than the said lightsensitive silver halide is dissolved. The metallic salt grains have not substantial sensitivity. It is to be understood that the said metallic salt is "not substantially sensitized" by the light energy when light exposure is given with light energy necessary for making the light-sensitive silver halide sensitive to light. Light-sensitivity of the metallic salt grains is below 1/10 times of the light-sensitive silver halide, preferably below 1/50 times. And metallic ion or metallic complex ion which is produced as a result of that the metallic salt grains are dissolved, is reduced to metal on physical development nuclei in existence of reducing agent.

The metallic salt grains are preferably silver halide grains that have no light-sensitivity and are dissolved in a processing solution faster in comparison with the light-sensitive silver halide grains. More practically, the metallic salt grains preferably are selected from silver bromide, silver chloride or mixed silver halide thereof, and it is desirable that they are of finer grains than the said light-sensitive silver halide and further desirable that they are stabilized by stabilizers of various kinds. These grains of metallic salt are preferably used in the range from 0.1 mol to 10 mol for 1 mol of light-sensitive silver halide.One example of the aforementioned stabilizer is described in the Research Disclosure~ RD-9232 (December, 1971) and Rod~17643 (December,1978). These stabilizers are preferably used in the range of 0.01 g to 2.0 g for 1 mol of silver halide.

Furthermore, physical development nuclei have a function to accelerate like catalyzer the process in which the metallic ion or the metallic complex ion created by the dissolution of the metallic grains of the said metallic salt is reduced by the reducing agent to a metal. As a practical example, metallic colloid, metal sulfide colloid, or other metallic salt colloid dispersed in a binder is given.

As a binder in this case, gelatin, silica sol, polyvinyl alcohol, gum arabic, agar-agar, cellulose derivative and the like are usable and the method of preparation of physical development nuclei is stated in the photographic silver halide diffusing process (The Focal Press, 1 972, London and New York) for example.

The less-solubilizer optionally added is selected from the compounds that is adsorbed to the metallic salt grains that are the particles of more soluble metallic salt per se and lower the solubility of the metallic salt grains. These compounds are mercapto compounds for example and more practically, cysteine, 1 -phenyl-5-mercapto tetrazole, mercapto benzthiazole or the like are included as a typical practical example. Further, thiourea indazole, triazole or imidazole compound is preferably used in this invention. The adding amount of the less-solubilizer is preferably 10-2 mol to 10-4 mol per one mole metallic salt.

Further, the dissolving substance is the substance that acts on the metallic salt grains and bears the metallic ion or soluble metallic complex ion and as a typical practical example, sulfite such as sodium sulfite, thiosulfate such as sodium thiosulfate, ammonium thiosulfate, cyanate such as potassium cyanate or the like, thiocyanate such as sodium thiocyanate, ammonium thiocyanate, amino acid compounds such as cystine, cysteine, thiourea compounds such as thiourea,3,6-dithia-1,8- octasiol and thioether compounds are given. The metallic salt grains are preferably less solubilized by means of chemical compound than the metallic grain per se.

The processing liquid is a developing liquid for monochrome silver halide photographic material but further containing the dissolving substance. The value of pH, temperature and processing period are determined by referring a conventional development.

Reducing agent in a processing liquid is selected from developing agent. Examples are hydroquinone, 4-N-methylaminophenyl, ascorbic acid, isoascorbic acid, 2,6-dimethyl-4-aminophenol, methyl-hydroquinone, 2,6-dimethyl hydroquinone, 2-methyl-4-a mino-6-methoxyphenol, 2,6- dimethoxy-4-aminophenol, 2 ,5-dimethyl hydroquinon, 2 ,4,6-triaminophenol, 2,4-diaminophenol, N,Ndiethyl-hydroxylamine and 4,6-diamino-ortho-cresol.

Further, organic amine such as diethyl amine or the like as well as inorganic alkaline agent such as caustic soda, sodium carbonate or the like are added to the processing liquid as an alkaline agent.

Besides, it is possible to add to the said developing solution as occasion calls the additives such as development inhibitor, toning agent, hardening agent and development accelerating agent that are conventionally used.

Further, some embodiments are considered concerning a layer arrangement in this invention.

Three ingredients of high sensitive silver halide, metallic salt that substantially has no light-sensitivity such as silver chloride and physical development nuclei are contained in the same layer that is coated on the support, or the emulsion layer containing metallic salt that substantially has no lightsensitiveness such as silver chloride and physical development nuclei in the same layer is coated on the support and on this layer an emulsion layer that contains high sensitive silver halide is coated is most preferable.

This invention will be explained more practically with typical examples as follows.

EXAMPLE 1 (Preparation of more soluble metallic salt) Silver chloride gelatin emulsion was prepared by adding water solution of 200 ml in which sodium chloride of 24.8 g is dissolved into water solution of 1000 ml having silver nitrate of 60 g and gelatin of 30 g dissolved therein and being stirred constantly at 500 C. Then, this emulsion after being washed by the ordinary depositing method, was dispersed again in water solution of 800 ml that contains 400 ml of 4-hydroxy-6-methyl-1 ,3,3a,7-tetrazaindene having 38 g of gelatin dissolved therein. An average diameter of the particle of silver chloride crystal obtained therefrom was 0.1 microns.

(Preparation of high sensitive silver halide emulsion) After being sensitized by an ordinary gold-hypo sensitizing method, silver iodo-bromide that contains 7 mol percent of silver iodide prepared from silver nitrate, sodium bromide and sodium iodide with an ordinary ammonia method, was dispersed in water solution containing 4-hydroxy-6-methyl 1 ,3,3a,7-tetrazaindene with 1 to 1 ratio of silver to gelatin. Thus, high sensitive silver iodo-bromide emulsion was prepared.

Next, to silver chloride emulsion prepared as mentioned above, physical development nuclei colloid obtained from sodium sulfide, silver nitrate and zinc acetate all mixed and dispersed in gelatin water solution was added and further saponin was added as a surface wetting agent and the emulsion was coated on the subbing treated polyester base in a manner that the quantity rate of silver of silver chloride emulsion is 3.0 g/m2 and that of physical development nuclei is 0.01 g/m2; further onto such layer, high sensitive silver iodo-bromide emulsion prepared as mentioned above was coated in a manner that the quantity rate of silver is 3.0 g/m2, after the addition of succinic acid-2-ethylhexylsodium estermonosulfonic acid as a surface wetting agent; further into the layer, a gelatin layer in which formalin and glyoxal were added as a gelatin hardening agent was coated as a protection layer; thus, the light-sensitive material was prepared and after being given an optical wedge exposure with the light of 3.2 CMS, it was processed for development at 350C for 60 seconds with the following developing solution and then fixing, washing and drying were given thereto.

[Formula of developing solution] Hydroquinone 12.0 g 1 -phenyl-1 ,3-pyrazolidone 1.0 g Sodium sulfurous acid anhydride 65.0 g Potassium hydroxide 15.0 g Sodium thiosulfate (5H2O) 4.0 g 1-phenyl-5-mercaptotetrazole Q.005 g Add water to make 1,000 ml As a result of the foregoing, the negative image of high fog density with maximum density of 3.35 and minimum density of 1.03 was obtained. For this, the results of treatment with an addition of 9.2 x 10-4 mol/l of various inhibitors in the following table to the aforementioned developing solution, are shown in the Table 1.

TABLE 1

Dmax Dmin decreasing decreasing No. Example of compound rate rate 1 3-amino-5-mercapto-1 2,4- 16.6% 2.1% triazole (comparison example) 2 6-benzylaminopurin 40.2% 63.1% (comparison example) 3 1 -phenyl-5-mercapto-tetrazole 19.8% 48.0% (comparison example) 4 illustrated compound of this 9.0% 56.3% Invention (3) 5 " (6) 5.6% 62.5% 6 " (8) 6.6% 61.2% 7 ,, (1) 10.8% 52.2% 8 " (16) 11.0% 51.8% As is clear from the Table 1, it is recognized that the development processing method by the processing solution to which the compound of this invention is added is an excellent method with a high decreasing rate of fog density and a low decreasing rate of the maximum density for the light-sensitive photographic material with a composition of this invention.

EXAMPLE 2 A light-sensitive material is prepared by using with emulsion, which is added with 100 mg of potassium bromide and 250 mg of 1 -phenyl-5-mercaptotetrazol instead of pure silver chloride emulsion of the Example 1, into silver chloride emulsion which is prepared in the Example 1, and by using with the others which remain at all unchanged as they are in the Example 1, and then optical wedge exposure is made by light at 3.2 CMS, and developing process is made by the undermentioned developing solution at 350C and for the period of 60 seconds, and thereafter fixing, washing and drying are made, and then as the result, a negative image of Dmax 3.23 and Dmin 1.10 is obtained, and further, 0.49 each of chemical compounds (6), (8) and as a comparison compound, 2,5-dimercapto-1 ,3,4-thiadiazol respectively to 1000 ml of the developing solution are added and the results are shown in Table 2.

[Formula of developing solution] Hydroquinone 12.0 g 1-phenyl-1,3-pyrazolidone 1.0 g Sodium sulfite anhydrous 65.0 g Potassium hydroxide 15.0 g Sodium thiosulfate (5H20) 4.0 g Potassium bromide 0.5 g Add water to make 1,000 ml TABLE 2

Dmax Dmin decreasing decreasing No. Chemical compounds rate rate 1 2,5-dimercapto-1 ,314-thiadiazol 2.3% 1 (comparison example) 2 2 chemical compound of this 6.2% 65.1% invention (6) 3 " (8) 6.5% 62.4% As clear as the examples, anti-fogging agent for inhibiting fog on the said image has a limited selectivity, and the chemical compounds of the invention can display superior effectiveness by combining with the said method.

Claims (8)

1. A method for forming a negative image which comprises an imagewise exposing a photographic material having on a support (1) light-sensitive silver halide grains, (2) substantially nonlight-sensitive metallic salt grains which are more soluble than the light-sensitive silver halide grains and (3) nuclei for physical development, and treating the photographic material in the presence of a compound represented by the following formula with a processor containing a reducing agent and a substance which dissolves the non-light-sensitive metallic salt grains::

[In the formula ,X, Y and Z respectively represent a nitrogen atom or CR group (R represents a hydrogen atom, or a lower alkyl or aryl group), R, and R2 respectively represent a hydrogen or halogen atom, or a lower alkyl, lower alkoxy, aryloxy, NO, NO2, CN, COR3, SO2R4, OH, aryl or

group (R3 and R4 respectively represent a hydrogen atom, or a lower alkoxy, OH, lower alkyl, aryl, aryloxy or OH group, R5 and R6 respectively represent a hydrogen atom, or a lower alkyl or aryl group) ] .

2. A method according to claim 1 wherein the non-light-sensitive metallic salt grains are less soiubilized by a less solubilizer.

3. A method according to claim 1 wherein Y in the formula [I] is a nitrogen atom.

4. A method according to claim 1 wherein X and Z in the formula [I] is CH group.

5. A method according to claim 1 wherein Rr or R2 is an NO, group.

6. A method according to claim 1 wherein the compound of the formula [I] is

7. A method according to any one of claims 1 to 5 wherein R1 and/or R2 is a trifluoromethyl group.

8. A method according to claim 1 substantially as described in Example 1 or 2.