Direct Positive-type Multi-layer Light-sensitive Material

Abstract

A direct positive type photographic material having a high information packing capacity, which is in particular, a multi-layer direct positive-type light-sensitive material comprising, on a suitable support member, at least two emulsion layers with the emulsion layers being selected from (A) a chemically fogged direct positive-type emulsion in which at least one of a halogen acceptor and an electron acceptor is adsorbed on the silver halide grains having free electron trapping nuclei in the grains, (B) a chemically fogged direct positive-type emulsion in which at least an electron acceptor is adsorbed on the silver halide grains substantially free from positive hole trapping nuclei in the grains, and (C) a chemically fogged direct positive-type emulsion in which at least a halogen acceptor is adsorbed on the silver halide grains having free electron trapping nuclei in the grains but substantially free from positive hole trapping nuclei in the grains, said emulsion layers being composed of the same type emulsion layers or different type emulsion layers having an intermediate layer therebetween.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a direct positive-type multi-layer light-sensitive material having at least two layers of silver halide emulsions, in a particular combination, in which an electron acceptor and/or a halogen acceptor is absorbed or chemically fogged silver halide grains with the layers being selectively and directly-reversal sensitized to a particular wavelength range. More particularly, it is concerned with a direct positive-type multi-layer color light-sensitive material.

2. Description of the Prior Art

With the advent of the information age, information recording materials having a high information packing capacity have been desired, by which recording can be carried out rapidly and simply. To this end, silver halide photographic materials appear to be suitable. A silver halide photographic material ordinarily results in a negative image by processings involving only one development. To obtain a positive image, therefore, such a negative image obtained by a series of developing processings has to be subjected to exposure and then to a series of developing processings again. Another method for obtaining a positive image from an object is a reversal developing system which comprises ordinarily a first development, a water washing, a bleaching, a water washing, a cleaning bath, a water washing, an exposure or fogging bath, a second development, a fixing and a water washing. Color reversal development processing comprises a first black-and-white development, a stopping, a hardening bath, a water washing, an exposure or fogging bath, a water washing, a color developing bath, a water washing, a bleaching, a water washing, a fixing, a water washing and a stabilizing bath, which are generally time consuming and very complicated. In general, it is more advantageous to record an object as a positive image.

There are a number of methods to increase the recording information capacity of a silver halide photographic material. If the resolving power, sharpness and grain property of an image are improved then the information capacity per unit area can be increased. It is knwon to raise the information density by increasing the thickness when the light-sensitive material is multi-layer. It is also known to raise the recording density by varying the wavelength range of the spectral sensitization of each silver halide photographic emulsion used. For example, electron rays, x-rays, ultraviolet rays, blue light, green light, yellow light, red light and near infrared rays can be classified by wavelengths and recorded and the recording density can be raised by varying the color hue (the spectral adsorption characteristic) of the recorded image, for example, by the use of a yellow image, a magenta image, a red image, a cyan image and a blue image.

Furthermore, direct positive-type silver halide photographic emulsions which have been previously chemically fogged have a much higher developing speed than a photographic emulsion having a latent image obtained by the ordinary negative type exposure. Therefore, this is very advantageous to a rapid process.

It is further advantageous from a commercial standpoint that the direct positive-type silver halide photographic material designed for a specific use is able to give a positive image directly from an object by subjecting such a material to the usual color paper processing, litho-type development, color positive-type development for movie use, x-ray rapid development or color negative processing. To obtain such a multi-layer, direct positive type silver halide photographic material, there are more difficulties on the composition of at least two emulsion layers as compared with the commonly used multi-layer negative light-sensitive material. The instant invention solves this technically difficult problem.

A first object of the invention is to obtain a direct positive-type light-sensitive material having a high information recording capacity, in particular, a multi-layer direct positive type light-sensitive material comprising at least two layers.

A second object of the invention is to obtain a multi-layer, direct positive-type light-sensitive material by which a positive image from a positive object or a negative image from a negative object can be obtained economically and in a short period of time through the use of only the ordinary series of negative developing processings.

A third object of the invention is to obtain a multi-layer, direct positive-type photographic material whose information recording capacity is raised by varying the sensitized wavelength region of each silver halide photographic emulsion layer.

A fourth object of the invention is to obtain a direct positive-type color photographic material whose information recording capacity is raised in place of the color hue (the spectral adsorption characteristic) of a directly obtained positive image.

A fifth object of the invention is to obtain a direct positive-type silver halide photographic material whose exposure latitude is enlarged by use of a composition of at least two layers and whose information recording capacity is raised with a change in the quantity of exposure. Further objects of the invention will be apparent from the following detailed description.

SUMMARY OF THE INVENTION

The above described objects of the invention can be accomplished by a direct positive-type multi-layer light-sensitive material comprising, on a suitable support, at least two emulsion layers selected from the group consisting of (A) a chemically fogged direct positive-type emulsion in which at least one of a halogen acceptor and an electron acceptor is adsorbed on silver halide grains having free electron trapping nuclei inside the grains, (B) a chemically fogged direct positive-type emulsion in which at least a halogen acceptor is adsorbed on silver halide grains which are substantially free from positive hole trapping nuclei inside the grains, and (C) a chemically fogged direct positive-type emulsion in which at least an electron acceptor is adsorbed on silver halide grains having free electron trapping nuclei inside the grains but substantially free from positive hole trapping nuclei inside the grains, said emulsion layers being composed of the same type of emulsion layer or a different type of emulsion layer having an intermediate layer therebetween.

The multi-layer, direct positive-type light-sensitive material according to the invention is capable of giving a positive image rapidly, simply and directly utilizing the commonly used negative developing process for black-and-white or color photography.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 to FIG. 3 and FIG. 19 to FIG. 25 show, for comparison, the characteristic curves obtained from various light-sensitive materials according to the invention.

FIG. 4 to FIG. 7 show schematically the layer structure of direct positive-type silver halide photographic emulsions according to the invention.

FIG. 8 to FIG. 18 show spectrograms of films on which complete emulsions of the invention are coated.

DETAILED DESCRIPTION OF THE INVENTION

The multi-layer, direct positive-type light-sensitive material comprising at least two layers provided by the present invention is applicable to miscellaneous uses such as: reproduction of an original consisting of points, lines or patterns of at least two colors; recording or reproduction of an image consisting of at least two colors on a cathode-ray tube; formation of a contour image from a predetermined object, enlargement or duplication of a color photograph from a color transparent positive or negative photograph using one conventional color development prosess; and duplication of a radiograph.

Ordinarily the following disadvantages occur when the commonly used direct positive emulsions are stacked corresponding to the arrangement used in a multi-emulsion layer using negative-type emulsions. The direct positive emulsion having a high sensitivity, a hard gradation and a good clearance loses these properties when stacked. A confusing of the spectral sensitivity distribution of the emulsion layers occurs and, in the case of a color photographic material, a surprising mixing of colors results. The invention provides a technique for coping with such disadvantages, which will be apparent from the detailed description and examples embodied.

1. The type of each direct positive emulsion (which will hereinafter be defined) is confined Preferably a multi-emulsion layer is composed of same type emulsions only.

2. An intermediate layer suitable for the invention is provided. To this intermediate layer are added a fine grain silver halide emulsion in an amount sufficient to prevent diffusion of an electron acceptor or a halogen acceptor, adsorbents, charged hydrophilic high molecular weight materials and surface active agents (including couplers). With a color photographic materials, in particular, a fine grain light-sensitive silver halide emulsion, a surface active agent and a color coupler are added to provide an auto-masking mechanism, thus preventing color mixing.

3. A simultaneous multi-layer coating method is used. Between the emulsions which are coated simultaneously, there is relatively little undesirable interaction due to the mutual diffusion of an electron acceptor or a halogen acceptor.

4. Other methods will be apparent from the following illustration.

The types of the direct positive-type silver halide emulsion used in the invention will now be illustrated in detail. These specific illustrations are not to be interpreted as limiting the invention thereby.

Emulsion A

A chemically fogged silver halide photographic emulsion having free electron trapping nuclei inside the silver halide grains:

This direct positive emulsion has nuclei capable of trapping free electrons inside the silver halide grains and the surface of the grains is chemically fogged. The free electrons generated in the fine crystals of silver halide by direct radiation of photons. On the other hand, the positive holes whose recombination with free electrons is interrupted attack the fog nuclei previously provided to the crystal surface, thus oxidizing the fog nuclei and inactivating the developing activity. Consequently, a positive image is directly formed by development depending on the quantity of the radiation received (that is, imagewise). Regarding Emulsion A, a number of techniques can be used for improving the intensification, i.e. raising the reversal sensitivity or for lowering the minimum density, i.e. improving the clearance.

First, electron trapping nuclei can be provided inside of the silver halide so as to prevent recombining of the positive holes and free electrons generated in the silver halide by radiation with photons.

A second technique is to provide fog nuclei which are chemically attacked by the positive holes thus losing readily the developing activity of the surface layer of the silver halide.

A third technique is to adsorb an electron acceptor capable of trapping any free electrons generated on the silver halide. The adsorbed electron acceptor will not trap positive holes.

Emulsion A is an emulsion which gives a positive image directly. This emulsion can be spectrally sensitized by adsorbing a halogen acceptor or sensitizing dye thereon. The halogen acceptor produces free electrons on the silver halide due to light excitation on radiation and, at the same time, produces positive holes on the surface of the silver halide. If the free electrons are trapped by free electron trapping nuclei inside the silver halide or trapped by the adsorbed electron acceptor and prevented from recombining with positive holes, the positive holes generated on the surface of silver halide attack the fog nuclei more readily and effectively making them development inactive.

A fourth technique is to maintain the silver halide grains at a suitable grain size so that the positive holes generated on the silver halide by radiation with photons are easily removed to the surface due to the effect of the surface electric field of the silver halide grain and thereby attack fog nuclei. The emulsion to which this technique can be applied has a high sensitivity and clearance. However, this unfortunately results in a gradation being hard and unsuitable for reproduction of details.

For Emulsion A, a silver chloride, silver bromide, silver iodide or a mixed silver halide thereof photographic emulsion is used. It is necessary to choose the halogen composition so that a chemical sensitizer or a group VIII metal salt used for providing free electron trapping nuclei may readily be incorporated in the silver halide. A characteristic of Emulsion A is that it is capable per se of giving a positive image directly and not only sensitization of the intrinsic absorption region but also spectral sensitization are made possible by the addition of a halogen acceptor.

The clearance is improved and the formation of a negative image is prevented by adding an electron acceptor. Furthermore, the addition of bromide ion or iodide ion results in increasing the optical density on a nonexposed area, raising of the sensitivity and improvement of the clearance.

Emulsion B

A chemically fogged silver halide emulsion substantially free from positive hole trapping nuclei inside the silver halide grains:

If some free electron trapping nuclei are provided to the silver halide, the free electron trapping function tends to accelerate the recombining of the positive holes. Emulsion B is a direct positive emulsion whose silver halide surface is chemically fogged and which is free from positive hole trapping nuclei and free electron trapping nuclei inside the silver halide. This is a silver halide emulsion consisting of a regular crystal which is as free from crystal defects as is possible and which is, preferably, a pure silver bromide, silver bromoiodide or silver chlorobromide free from twin surfaces. This emulsion per se gives no positive image directly. When an electron acceptor or a desensitizing dye is absorbed on Emulsion B, however, a high sensitivity direct positive image is obtained, which is spectrally sensitized and, even in the intrinsic absorption region, a high sensitivity positive image is obtained. When an electron acceptor and a halogen acceptor are adsorbed on the silver halide grains of Emulsion B, the clearance deteriorates markedly and the sensitivity is reduced. A halogen acceptor is quite suitable as a sensitizer for Emulsion A type but, for Emulsion B type, it has the disadvantages that the clearance deteriorates and the sensitization is reduced. This is noticed for the production of a direct positive photographic material consisting of at least two layers.

Emulsion C

A chemically fogged silver halide emulsion such as a silver chloride, a silver bromide, silver chlorobromide, a silver bromoiodide or a silver chlorobromoiodide emulsion, having free electron trapping nuclei inside the grains but which is substantially free from positive hole trapping nuclei inside the grains:

This is an emulsion consisting of such grains that free electron trapping nuclei are provided in the central nuclei of silver halide, the outer shell of which is covered by silver halide and the surface is chemically fogged.

Electrons generated in the silver halide on radiation are trapped by the central nuclei whereby the so-called internal latent image nuclei is formed. Since there are no free electron trapping nuclei in the outer shell, positive holes effectively attack fog nuclei very near the surface of silver halide grains and the probability of recombining with free electrons is low. Accordingly, Emulsion C has the features that it, per se, gives a direct positive image which is hard and has a high sensitivity and that it does not give a negative image even through exposure to more radiation, that is, the clearance is good.

At the present time, processes for the production of an emulsion having internal nuclei of this kind are well known (e.g., see Japanese Patent Publication 29405/1968). An example of the application thereof to a direct positive type emulsion is described in British Patent Application No. 16507/66. The use of a halogen acceptor is effective for Emulsion C as in the case of Emulsion A, but the effect of the electron acceptor is small.

A halogen acceptor and an electron acceptor and, above all, the halogen acceptor to be added to the emulsion used in the invention has such a weak adsorptive ability to silver halide grain that a larger amount has to be added than is used in the conventional negative emulsion. In the case of a multi-layer construction, the interlayer diffusion of an electron acceptor tends to become great and, in addition, the undesirable action of interlayer diffusion of a halogen acceptor becomes more marked in comparison with a negative emulsion. This effect is strengthened if a color coupler is present. In particular, a halogen acceptor has the disadvantage that, particularly if Emulsion B is only slightly contaminated by it, the direct reversal sensitivity is lost.

Technical aspects of the production of emulsions of various types used in the invention will now be illustrated in detail.

The fog nuclei in the invention are provided by previously chemically fogging a silver halide emulsion, that is, by adding an inorganic reducing compound, such as stannous chloride or boron hydride, or an organic reducing compound, such as a hydrazine derivative, formalin, thiourea dioxide, a polyamino compound, aminoborane or methyldichlorosilane. The fogged nuclei of the invention, whose keeping property is improved, tend to be decomposed by positive holes. That is to say, the fogged nuclei are obtained using a fogging method which advantageously gives rise to high sensitization and good storage properties of a direct positive emulsion. For example, the combined use of melted. reducing agent with an ion more noble than silver ion or with a halide ion is known (e.g., see U.S. Pat. Nos. 2,497,875; 2,588,982; 3,023,102; and 3,367,778; British Pat. Nos. 707,704; 723,019; 821,251; and 1,097,999; French Pat. Nos. 1,513,840; 1,518,095; 739,755; 1,498,213; 1,518,094; 1,520,822; and 1,520,824; Belgian Pat. Nos. 708,563 and 720,660; and Japanese Pat. Publication No. 13488/1968).

In the past, it has been well known as a method for raising the internal sensitivity of a silver halide photographic emulsion to provide free electron trapping nuclei to the inside of the silver halide. There are various methods wherein iodide ion is incorporated in a non-chemically ripened emulsion, the outer shell of the silver halide having light-sensitive nuclei obtained by chemical ripening is further coated with pure silver halide to convert them into internal nuclei, and a Group VIII metal salt or Group Ib salt is added during the step of forming a precipitate of the silver halide (e.g., see U.S. Pat. Nos. 2,401,051; 2,717,833; 2,976,149 and 3,023,102; British Pat. Nos. 707,704; 1,097,999 and 690,997; French Pat. Nos. 1,520,822; 1,520,824; 1,520,817 and 1,523,626; Japanese Pat. Publication Nos. 4125/1968 and 29405/1968, and Belgian Pat. Nos. 713,272; 721,567 and 681,768).

It is necessary, in order to avoid providing positive hole trapping nuclei to the inside of the silver halide, to use cubic system or tetragonal system grains both having the surface (100) free of twin surfaces and having a regular crystal habit substantially free of crystal defects so as not to provide free electron trapping nuclei to raise the probability of recombining with free electrons to at least the "sub-surface layer" near the surface of the grain (e.g., see British Application Nos. 11291/67, 11292/67 and 16507/66).

For the emulsion types used in the invention, gelatins, in particular, inert gelatins, are advantageously used as a protective colloid. In place of natural gelatins, photographically inert gelatin derivatives and water-soluble synthetic polymers, for example, polyvinyl acrylate, polyvinyl alcohol, polyvinylpyrrolidone and polyvinyl alginate may be used.

The electron acceptor, desensitizer or desensitizing dye used in the invention is a material which is generated in the silver halide grain by radiation with photons, which is capable of trapping free electrons and which is adsorptive on silver halide. It is further defined as a material having a minimum energy level of vacant electron which is lower than the electron energy level of the conduction band of the silver halide grain. Preferably, it is a desensitizing dye having a maximum energy level of occupied electrons, which is lower than the valency band of the silver halide grain. Measurement of the values of these energy levels is complicated, but is possible. For example, determination of these energy levels for a very simple symmetric cyanine dye is described in Photographic Science and Engineering by Tani and Kikuchi, Vol. 11 (3), page 129 (1967) and determination for a typical merocyanine dye is described in Preprint (No. B-12) of ICPS-1970 (Moscow) by Shiba and Kubodera. It is known that these electron energy levels correspond primarily to the anodic polarographic half-wave potential (Eox) and cathodic polarographic half-wave potential (Ered). Many of the foregoing compounds are disclosed in, for example, U.S. Pat. Nos. 3,023,102; 3,314,796; 2,901,351 and 3,367,779; British Pat. Nos. 723,019; 698,575; 698,576; 834,839; 667,206; 748,681; 796,873; 875,887; 905,237; 907,367 and 940,152; French Pat. Nos. 1,520,824; 1,518,094; 1,518,095; 1,520,819; 1,520,823; 1,520,821 and 1,523,626; Belgian Pat. Nos. 722,457 and 722,594, Japanese Pat. Publication Nos. 13167/1968 and 14500/1968. The electron acceptor used in the invention is a desensitizing dye whose cathodic polarographic half-wave potential (Ered) is more positive than -1.0 volt.

The halogen acceptor or sensitizing dye used in the invention is a material capable of producing free electrons in the silver halide grain while absorbing light itself while in the state of being adsorbed on silver halide photographic emulsion grains and, more importantly, is a material capable of producing positive holes having an energy sufficient to oxidize fog nuclei on the surfaces of the silver halide grains. The halogen acceptor cannot be defined absolutely in terms of its electron energy level, that is, by comparison of the energy levels of the valency band and the conducting band of silver halide, because, in many cases, the mechanism of energy transfer is attributed to the specific specific spectral sensitization process. Many known sensitizing dyes can act as a "halogen acceptor" in the state of M-band type adsorption either by themselves or with a suitable supersensitizer. That is to say, the halogen acceptor may be defined as a sensitizing dye of the M-band type.

The halogen acceptor used in the invention is preferably a sensitizing dye whose cathodic polarographic half-wave potential is more negative than -0.7 volt and difference between the cathodic polarographic half-wave potential and the anodic polarographic half-wave potential is greater than 1.5 volts. Such a compound is, for example, selected from dyes described in U.S. Pat. Nos. 2,497,876 and 3,364,026, French Pat. Nos. 1,520,822 and 2,012,545, British Pat. No. 655,009 and German Pat. No. 1,190,331.

The value of the cathodic polarographic half-wave potential (Ered) is the value in volts of the potential at which the compound accepts an electron at the cathode. As used in this invention, it is determined using tetra-n-propylammonium perchlorate as a support electrolyte, a dropping mercury electrode at 25.degree.C in a solution of acetonitrile with a saturated calomel electrode as a reference electrode, and further it is measured in a solution of acetonitrile at a concentration of from 1 .times. 10.sup..sup.-4 mol to 1 .times. 10.sup..sup.-6 mol.

The value of the anodic polarographic half-wave potential (Eox) is the value in volts of the potential at which an electron is withdrawn from the compound at the anode. As in the case of Ered, it is measured using a rotary platinum electrode as the anode and sodium perchlorate as a support electrolyte according to the method described in German Pat. No. 2,010,762.

The amount added of the electron acceptor or the halogen acceptor used in the invention may be varied depending on the amount of silver halide in an emulsion, the size of the surface area of the silver halide and the object of the element's use. The halogen acceptor is used in a greater amount than is used than in the conventional negative type emulsion, because there is no desensitizing action due to a sensitizing dye occurring in the negative emulsion. The above described amount to be added may preferably range from about 1 .times. 10.sup..sup.-6 to about 1 .times. 10.sup..sup.-3 mol of halogen acceptor or electron acceptor per mol of silver salt. These compounds may be coated in admixture or individually after being dissolved in water or a water-miscible solvent, such as methanol, ethanol, methyl cellosolve, methyl ethyl ketone or pyridine. For this dissolving, agitation using ultrasonic waves may be employed.

Moreover, numerous methods for the spectral sensitization of the negative emulsion may be employed, for example, such as those described in Japanese Pat. Application 8231/1970, Japanese Pat. Publication Nos. 23389/1969; 27555/1969, and 22948/1969, U.S. Pat. Nos. 3,485,63; 3,342,605 and 2,912,343 and German Offenlegungsschrift No. 1,947,935.

The intermediate layer used in the invention must have different characteristics from those commonly used in a negative-type multi-layer light-sensitive material. That is to say, on the characteristics of the intermediate layer, efforts have to be made to prevent diffusion of the electron acceptor or halogen acceptor. Fine grain silver halide or silica, for example, a grain size less than about 0.2 microns, is contained therein in an amount sufficient to prevent diffusion for example, less than 75 g/100 g of dry gelatin. In the case of a negative emulsion type multi-layer light-sensitive material, provision of such an intermediate layer desensitizes an adjacent layer. If the intermediate layer is provided in a direct positive type multi-layer light-sensitive material, on the other hand, the sensitivity of silver halide grain in the intermediate layer is lowered due to the adsorption of the electron acceptor and an adjacent layer is not desensitized in spite of the fact that a larger amount is used than in the case of the negative type. A high molecular weight anionic organic compound or anionic surface active agent such as sodium naphthalenesulfonate described in Japanese Pat. Publication 23309/1965 and 23310/1965 is added in an amount sufficient to prevent diffusion of the halogen acceptor or electron acceptor by static reaction or solubilization, for example, from about 5 to 50 g per 100 g of gelatin. Preferably a fine grain light-sensitive silver halide having a suitable negative sensitivity and suitable for prevention of the diffusion thereof may be mixed with a suitable amount of a color coupler to thus give an automatic masking mechanism in a direct positive-type multi-layer light-sensitive material. The combined use of a cationic hydrophilic polymer can prevent diffusion of the electron acceptor or halogen acceptor having acidic groups. Further this may previously be dyed so that it will function additionally as a light filter layer, an irradiation prevention layer and an antihalation layer. Suitable cationic hydrophilic polymers which can be used in the invention are, for example, polymers of 2-methyl-1-vinylimidazole, the quaternized derivatives thereof, polymers of vinylpyridine, and polymers of N,N-dialkylaminoethyl methacrylate and quaternized derivatives thereof. From 2 to 20 g of these polymers is used per 100 g of dry gelatin. Anionic hydrophilic polymers which are suitable for use in this invention are, for example, polymers of acrylic acid and methacrylic acid and copolymers of maleic anhydride and styrene-sulfonic acid, and they can be used at a level of about 0.5 to 50 g per 100 g of dry gelatin.

EXPERIMENTS

Emulsion A

To a first solution (10 g of inert gelatin and 5 ml of a 1 N solution of sodium chloride in 500 ml of water were warmed to 60.degree.C and dissolved) were constantly added a second solution (100 g of silver nitrate in 500 ml of water was warmed to 60.degree.C and dissolved) and a third solution (23 g of sodium chloride and 23 g of potassium bromide were dissolved in 150 ml of water, to which 50 mg of iridium (IV) potassium hexachloride was further added, and warmed to 60.degree.C) with agitation for a period of 20 minutes. Thereafter, 15 ml of a 0.2 N solution of potassium iodide was added, the mixture cooled and washed with water, followed by melting, adjusting the pAg to 4.0, adding hydrazine and potassium chloroaurate, adjusting the pH to 10, ripening for 10 minutes and neutralizing to a pH of 6.5 with citric acid. The temperature was lowered, followed by washing with water, a mixed solution of sodium chloride and potassium bromide is added, the pAg is adjusted to 7.0, and further a fourth solution (75 g of inert gelatin was dissolved in 300 ml of water) was added to give a silver halide emulsion. The so obtained silver halide emulsion, having an average grain size of 0.15 micron, consisted of regular tetragonal system grains, substantially all of the grains having the surface (100).

Emulsion B

To a first solution (8 g of inert gelatin and 5 ml of a 1 N solution of potassium bromide in 500 ml of water were warmed at 60.degree.C and dissolved) were added a second solution (100 g of silver nitrate in 500 ml of water was warmed at 60.degree.C and dissolved) and a third solution (70 g of potassium bromide in 150 ml of water was warmed at 60.degree.C and dissolved) gradually with agitation for a period of 50 minutes, followed by physical ripening for an additional 5 minutes, adding 15 ml of a 0.21 N solution of potassium iodide and then adjusting the pAg to 6.0 using a silver nitrate solution. Hydrazine and potassium chloroaurate were added, the pH was adjusted to 10 with a solution of caustic soda followed by ripening. The mixture was neutralized with citric acid, washed with water, melted and mixed with a fourth solution (75 g of inert gelatin was dissolved in 300 ml of water) to obtain a silver halide emulsion containing regular tetragonal system grains having an average grain size of 0.20 micron.

Emulsion C

This is prepared by the similar procedures to those of Emulsion A except for the following points:

To the first solution prepared as in Emulsion A were gradually added one half of the second solution prepared as in Emulsion A and A III - 1st solution (11.5 g of sodium chloride and 11.5 g of potassium bromide were dissolved in 75 ml of water, in which 50 mg of iridium potassium hexachloride was additionally dissolved) with agitation for a period of 10 minutes, followed by ripening for 5 minutes. Then the remaining half of the second solution and III - 2nd solution (11.5 g of sodium chloride and 11.5 g of sodium bromide were dissolved in 75 ml of water) were gradually added for 20 minutes. Thereafter, a similar procedure to that described for Emulsion A is repeated thus obtaining a silver halide emulsion consisting of regular tetragonal system grains having the surface (100) and an average grain size of 0.18 micron.

Typical embodiments of making Emulsions A, B and C are shown above. Delicate physical ripening conditions, for example, the shape of a vessel, stirring blade, stirring speed and feed positions of the second solution and the third solution, the degree of water washing and other delicate fogging conditions affect largely the photographic characteristics.

To each of the silver halide emulsions were added a specifica electron acceptor or halogen acceptor (as shown in Table 1) and a hardener such asa formalin, dichloro-5-hydroxytriazine, or chromium alum, and a coating aid, such as saponin or nonyl-benzene sulfonate and coated onto a transparent cellulose triacetate film to thus obtain a direct positive sensitive material. It was subjected to light wedge exposure using a tungsten light of 2854.degree.K as a light source, and developed at 20.degree.C for 2 minutes using a developer of the following composition. The density of the thus obtained strip was measured using of an S-type densitometer made by the Fuji Photo Film Co. The results obtained are shown in FIGS. 1, 2 and 3 in which the characteristic curves are given.

The structural formulas of the electron acceptor and the halogen acceptor used are shown in the following:

Halogen Acceptors: ##SPC1##

Electron Acceptors: ##SPC2##

Developer Composition Water (about 50.degree.C) 500 ml Metol 3 g Anhydrous Sodium Sulfite 45 g Hydroquinone 12 g Sodium Carbonate Monohydrate 80 g Potassium Bromide 2 g Water to 1000 ml

Table 1 __________________________________________________________________________ No. Emulsion Halogen Acceptor Electron Acceptor Characteristic 100 g (mol conc) ml (mol conc) ml Curve __________________________________________________________________________ 1 Type A -- -- FIG. 1 Curve 1 (a) (2 .times. 10.sup.-.sup.3) 8 -- 2 -- (m) (8 .times. 10.sup.-.sup.3) 4 3 (a) (2 .times. 10.sup.-.sup.3) 8 (m) (8 .times. 10.sup.-.sup.3) 4 4 (a) (2 .times. 10.sup.-.sup.3) 8 (o) (1.6.times.10.sup.-.sup.2) 4 5 2 Type B -- -- FIG. 2 Curve 1 (b) (2 .times. 10.sup.-.sup.3) 2 -- 2 -- (n) (4 .times. 10.sup.-.sup.3) 4 3 -- (o) (1.6.times.10.sup.-.sup.3) 4 4 (a) (2 .times. 10.sup.-.sup.3) 2 (n) (4 .times. 10.sup.-.sup.3) 4 5 (b) (2 .times. 10.sup.-.sup.3) 2 (n) ( do. 6) 4 3 Type C -- -- FIG. 3 Curve 1 (b) (2 .times. 10.sup.-.sup.3) 4 -- 2 -- (m) (8 .times. 10.sup.-.sup.3) 4 3 (b) (2 .times. 10.sup.-.sup.3) 4 (m) (8 .times. 10.sup.-.sup.3) 4 4 __________________________________________________________________________

It will be apparent from the results obtained in Experiments No. 1, No. 2 and No. 3, and shown in FIG. 1 that the effects of the electron acceptors and halogen acceptors on the direct reversal characteristics differ markedly in Emulsions A, B and C. In Emulsion A, for example, electron acceptor (b) does not raise the reversal sensitivity very much, but a negative image to be formed with an increase of exposure is remarkably suppressed and the clearance is improved. On the other hand, Emulsion B does not give a direct positive image by itself but the reversal sensitivity can be raised markedly by the addition of an electron acceptor. In Emulsion C, the effect of the electron acceptor is less than in Emulsion A. The halogen acceptor raises markedly the reversal sensitivity in Emulsion A and, at the same time, tends to form a negative image with an increase of exposure. This can be suppressed by the combined use with an electron acceptor. It is also observed in Emulsion C that the reversal sensitivity is markedly raised. In Emulsion B, however, the coexistence of the halogen acceptor ((a) and (b) in Experiment No. 2) weakens the reversal property, lowers the reversal sensitivity and deteriorates the clearance. Other additives to be added to the emulsion, for instance, color couplers, coating aids, stabilizers, development accelerators and hardeners exhibit different photographic effects according to the kind of emulsions, Emulsions A, B and C.

In the direct positive-type multi-layer light-sensitive material according to the invention, at least two coating emulsions of the invention are applied to a suitable support base using a simultaneous multi-layer coating method as disclosed in, for example, U.S. Pat. No. 2,761,791. The system of coating the emulsion layers individually is most disadvantageous, because simultaneous multi-layer coating can substantially reduce deleterious interactions between the emulsion layers. However, when an emulsion or gelatin solution is coated thereonto, the interaction between the previously coated layers increases. Such disadvantageous "interaction between emulsion layers" can be avoided by provision of a specific intermediate layer as illustrated before.

The disadvantageous interaction between emulsion layers consisting of at least two layers due to mutual diffusion of the electron acceptors and the halogen acceptors used in the emulsions can be solved by the using of those materials which have a strong adsorptive capacity on the silver halide grains and by provision of a specific intermediate layer. In the case of high interaction emulsion types, for example, Emulsions A and B or Emulsions C and B, the simultaneous multi-layer coating technique is very effective.

The above described improved method which is necessary for provision of a high quality direct positive-type multi-layer light-sensitive material is for the first time clarified by the instant invention.

The particularly preferred electron acceptors used in the invention are compounds represented by the following General Formula (I) or (II).

General Formula (I) ##SPC3##

or ##SPC4##

wherein Z is an atomic group necessary for forming a heterocyclic ring, R is an alkyl group of 1 to about 6 carbon atoms or a substituted alkyl group, a and n each is 1 or 2 and X is an anionic group used conventionally for cyanine dyes. (This compound is described in German Offenlegungsschrift No. 1,935,311.)

General Formula (II) ##SPC5##

wherein Z is an atomic group necessary for forming a cycloheptatriene ring, Z.sub.1 is an oxygen atom, an --NH-- group or an --N= group, A is = 0, a halogen atom or a pyrimidium group and B is a hydrogen atom, an alkoxycarbonyl group or an ##SPC6##

group, in which L.sub.1 and L.sub.2 are methine groups, Z.sub.2 is an atomic group necessary for forming a heterocyclic ring usually used for cyanine dyes, R is an alkyl or substituted alkyl group, X.sup.- is an anion conventionally used for forming cyanine dye and m and n each is 1 or 2. (This compound is described in Japanese Patent Application 91238/1969 U.S. Ser. No. 90,070 filed Nov. 6, 1970.)

On the other hand, the particularly preferred halogen acceptors used in the invention are xanthene type dyes or cyanine dyes used in a conventional photographic emulsion.

As such a xanthene type dye, a dye represented by the following General Formula (III) is preferably used.

General Formula (III) ##SPC7##

wherein X.sub.1, X.sub.2, X.sub.3, X.sub.4 and X.sub.5 each is a hydrogen atom or a halogen atom, q is 1, 2, 3 or 4 and M is a hydrogen ion, an alkali metal ion or an ammonium ion. (This compound is described in German Offenlegungsschrift 1,935,311.)

The cyanine dye which is suitable is a dye, for example, represented by the following General Formula (IV).

General Formula (IV) ##SPC8##

in which Z and Z.sub.1 are atomic groups for forming heterocyclic rings used conventionally as cyanine dye nuclei, such as .beta.,.beta.'-naphthoxazole, indolenine, benzothiazole, .alpha.-naphthothiazole and 4-quinoline nuclei, R and R.sub.1 each is an alkyl group, an allyl group or an aryl group, L.sub.1, L.sub.2 and L.sub.3 are methine groups such as --CH=, --C(CH.sub.3)=,--C(C.sub.2 H.sub.5)= and ##SPC9##

X.sub.1 is an anionic group used conventionally for cyanine dyes, p, q and m each is 1 or 2 and n is 1, 2 or 3. (This compound is described in Japanese Patent Application 47380/1970 U.S. Ser. No. 149,272 filed June 2, 1971, German Offenlegungsschrift 2,000,587, and Japanese Patent Publications 32741/1970 and 550/1971.)

The cyanine dye, merocyanine dye and rhodacyanine dye of the invention are used together with a supersensitizer represented by the following General Formula (V) whereby the sensitivity of a photographic emulsion is raised and the clearance is improved.

General Formula (V) ##SPC10##

in which R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each is a halogen atom, a hydroxyl group, an alkoxyl group, an aryloxy group, an arylthio group, an amino group, an alkylamino group and an arylamino group, Y.sub.1 and Y.sub.2 each are CH or a nitrogen atom and D is a divalent aromatic group such as ##SPC11##

This compound is suitable for supersensitization of a sensitizing dye capable of spectrally sensitizing in the wavelength region of 600-720 nm of the M-band. Examples of compounds suitable for use in the invention are given in the following. These examples should not be interpreted as limiting the invention. ##SPC12## Values of the Anodic Polarographic Half-wave Potential (Eox) and the Cathodic Polarographic Half-wave Potential (Ered)

Table 2 ______________________________________ Eox Ered (volt) (volt) ______________________________________ (a) 0.575 -1.410 (b) 1.047 -1.040 (c) 0.458 -0.512 (d) 0.400 -0.728 (e) 0.600 -1.630 (f) 0.374 -1.723 (g) 0.670 -1.057 (h) 1.005 -1.092 (i) 0.739 -1.405 (j) 0.367 -1.133 (k) 0.414 -1.054 (l) 2.0 -1.875 (m) 2.0 -0.565 (n) 1.292 -0.459 (o) 1.360 -0.563 (p) 1.240 -0.561 (q) 2.175 -0.325 (r) 1.881 -0.619 (s) 1.346 -0.644 (t) 2.0 -0.465 (u) 1.329 -0.791 (v) 1.073 -0.494 ______________________________________

Examples of Couplers ##SPC13##

These color couplers are compounds capable of obtaining a color image using a color developing agent consisting of a p-phenylenediamine derivative such as, 1,2,4-triaminobenzene, 1,2,4-triamino-5-methylbenzene, 2,3,6-triaminopyridine, 2-methylparaphenylenediamine, 2,5-dimethyl-p-phenylenediamine, N-(p-dimethylaminophenylglycine, N,N-diethyl-p-phenylenediamine and the like, see for example, U.S. Pat. No. 2,193,015 and the active methylene position of the color coupler may, during color developing, be substituted by a substituent which can be split imagewisely on development, for example, a substituent used in the conventional two equivalent type coupler, such as a halogen atom, a diazoaryl group, an arylthio group, an aryloxy group or a carbonylgroup as disclosed in U.S. Pat. Nos. 3,311,476; 3,408,194; 3,419,391; and 3,417,928. Moreover, the production technique of the multi-layer direct positive type color photographic material consisting of at least two layers according to the invention is available for the color diffusion transfer system as well as the silver dye bleaching system which is well known in obtaining a color image.

Examples of the layer structure of a multi-layer photographic material of at least two layers will now be given in order to illustrate the invention in greater detail.

I. direct positive type light-sensitive material whose exposure latitude is enlarged by the multilayer structure without any lowering of the direct reversal sensitivity

As illustrated hereinbefore, any of Emulsions A, B and C has the general characteristic of an emulsion which has a high sensitivity and improved clearance in that only a hard gradation is obtained. The commonly used method in the production of a light-sensitive material using the conventional negative type emulsion in order to enlarge the exposure latitude, for example, by mixing of different emulsions, by formation of a multi-layer element or by addition of a dye results in not only a lowering of the reversal sensitivity and but also in a deterioration of the clearance. The present invention has a layer structure free from these disadvantages.

In FIG. 4, 1 is a support member, 2 and 3 are respectively direct positive-type emulsion layers and 4 is a protective layer which can be provided if desired.

FIG. 5 shows another embodiment wherein intermediate layer 5 is provided between emulsion layers 2 and 3 of FIG. 4. Provision of the intermediate layer can reduce any undesirable interaction occurring in the preparation of 2 and 3. In this intermediate layer superfine grain low sensitivity silver halide grains, silica grains, charged hydrophilic protective colloids, surface active agents and charged high molecular weight compounds such as sodium substituted naphthalenesulfonate are preferably added in order to prevent undesirable diffusion or transfer of the halogen acceptor or electron acceptor.

Table 3 shows examples of this layer structure.

Table 3 __________________________________________________________________________ Emulsion 3 Emulsion 2 No. Emulsion Sensitiz- Emulsion Sensitiz- Developing Type ing Sub- Type ing Sub- Method stance stance __________________________________________________________________________ 1 A or C Electron A or C Electron Black-and acceptor acceptor White + + development Halogen Halogen acceptor acceptor (lower sen- sitivity than Emul- sion 3) 2 B Electron acceptor A or C do. do. 3 A or C Halogen A or C Halogen Color acceptor acceptor development + + Electron Electron acceptor acceptor + + Color Color coupler coupler 4 B Electron B Electron do. acceptor acceptor + + Color Color coupler coupler 5 B do. A or C Halogen do. acceptor + Electron acceptor + Color coupler 6 A or C Halogen B Electron do. acceptor acceptor + + Electron Color acceptor coupler + Color coupler __________________________________________________________________________

No. 6 is produced using the simultaneous multilayer coating technique.

Ii. direct positive type color light-sensitive material of at least two layers differing in the spectral sensitization wavelength region and differing correspondingly in hue, by which a color image can be recorded

This is available for the duplication of drawings and the recording of color images and drawings in the display system of cathode ray tube.

Referring to FIG. 6, 1 is an antihalation layer and 2 and 4 are direct positive type emulsion layers. 3 is an intermediate layer provided if desired and 5 is a protective layer provided if desired. Intermediate layer 3 preferably has the functions of solving problems occurring due to undesirable diffusion and transfer of a halogen acceptor or electron acceptor, of acting as a filter layer, of protecting an emulsion layer thereon from irradiation and of improving the color separation due to the adjacent layer effect. For the filter layer or irradiation prevention layer, it is preferred to incorporate the conventionally used silver colloid and mordant consisting of the conventionally used acid dye as disclosed in U.S. Pat. Nos. 3,282,699 and 3,512,983, and the positively charged hydrophilic polymer.

Table 4 shows examples of this layer structure.

Table 4 __________________________________________________________________________ Emulsion Layer 4 Emulsion Layer 2 No. Type Sensitizing Sub- Type Sensitizing Sub- Develop- stance and stance and ing Color Coupler Color Coupler Method __________________________________________________________________________ 7 B Electron accep- A or C Electron accep- Color tor (green tor + (Halogen develop- sensitization) acceptor + ment + Supersensitizer Color coupler (red sensitiza- (cyan) tion) ) + Color coupler (red) 8 B do. B Electron accep- do. tor (red sen- sitization) + Color coupler (magenta) 9 A or C Electron accep- A or C Electron accept- do. tor + Halogen tor + (Halogen acceptor (ortho) acceptor + +Color Supersensitizer coupler (magen- (red sensitive) ) ta) +Color coupler (cyan) __________________________________________________________________________

Iii. direct positive type color sensitive material of at least three layers and involving a color coupler capable of giving a color image having spectral absorption characteristics corresponding to the different spectral sensitization wavelength regions

Onto a suitable support member are coated at least a blue-sensitive emulsion, green-sensitive emulsion and red-sensitive emulsion with a yellow coupler, magenta coupler and cyan coupler involved correspondingly. One wavelength region-sensitized emulsion layer may further be composed of a multi-layer by the above mentioned method I or II.

Thus a color positive photograph can directly be obtained from a transparent positive original through the ordinary negative type development, for example, developing treatment for color positive film for cinema, color paper or color negative film. For such emulsion layer structure, it is strongly required to overcome the difficulties on multiplication of layers of the direct positive type silver halide emulsion.

Referring to FIGS. 7, 2, 4 and 6 are direct positive type emulsion layers and 3 and 5 are intermediate layers coated as occasion demands, which functions correspond to 3 of FIG. 6. 1 is an antihalation layer coated if necessary. As the support member are used cellulose derivative films such as cellulose triacetate film and cellulose diacetate film, polyethylene terephthalate film, plastic film, baryta paper, resin laminated paper, synthetic paper and white film that is made opaque by a white pigment.

Table 5 shows examples of layer structure.

Table 5 __________________________________________________________________________ Emulsion Layer 6 Emulsion Layer 4 Emulsion Layer 2 No. Type Sensitizing Type Sensitizing Type Sensitizing Substance Substance Substance and Coupler and Coupler and Coupler __________________________________________________________________________ 10 B Electron B Electron A or Electron acceptor acceptor C acceptor + (blue sen- (green (Halogen sitive) + sensitive) acceptor + Color cou- +Color Supersensi- pler (yel- coupler tizer (red low) (magenta) sensitive)) +Color cou- per (cyan) 11 B do. B do. B Electron acceptor (red sensi- tive)+ Color coup- ler (cyan) 12 A or Electron do. do. C acceptor blue sen- sitive) + Color cou- pler (yel- low) 13 B Electron A or Electron A or Electron acceptor C acceptor + C acceptor + (green Supersensi- Halogen ac- sensitive) tizer (red ceptor (blue +Color sensitive) sensitive) coupler +Color cou- Color coup- (magenta) pler (cyan) ler (yellow) 14 A or Halogen A or Electron A or do. C acceptor C acceptor C +Super- +Halogen sensitizer acceptor (red sen- (green sen- sitive) + sitive + Color cou- Color cou- pler (cyan) pler (magenta) 15 B Electron do. B Electron acceptor acceptor (red sensi- (blue sensi- tive) + tive) + Color coup- Color coup- ler (cyan) ler (yellow) __________________________________________________________________________

In No. 15, Emulsion A or C is used for emulsion layer 4 while Emulsion B is used for emulsion layer 2. The foregoing disadvantages can be overcome by the simultaneous multi-layer coating of emulsion layers 2-4, preferably with an intermediate layer.

For the purpose of improving the color reproduction of a color light-sensitive material of this kind, techniques are used to improve the color separation between the emulsion layers. The first is to use a suitable filter layer and the second is to raise the sensitivity within a particular spectral sensitization wavelength region and to lower the unnecessary intrinsic sensitivity. To this end, it is important to select the type of emulsion and the electron acceptor or halogen acceptor. Preferably the electron acceptor is contained in Emulsion B. Application of a suitable simultaneous coating system is preferable to retain the above described advantage and yet to avoid the disadvantage caused by diffusion of a halogen acceptor to an adjacent layer. The third technique is to utilize the desensitizing effect of the adsorbed dye aggregate. The reversal sensitivity is almost lost within the aggregate band wavelength region occurring by formation of the aggregate. The fourth technique is to provide an automatic masking function to an intermediate layer by the combined use of a negative light-sensitive emulsion having a suitable sensitivity and a suitable color coupler. The fifth technique is to apply other techniques used conventionally for multi-layer negative emulsions.

The following examples are given in order to illustrate the invention in greater detail without limiting the same.

EXAMPLES

After selecting one of Emulsions A, B and C having the same composition as in the foregoing Experiments, 1 kg thereof was taken in a pot, heated at 40.degree.C and metled. A specific amount of a specific electron acceptor or halogen acceptor as described in Table 6 below was added and the mixture was allowed to stand for 15 minutes. Where necessary, a specific color coupler (also described in Table 6) was added. Where a water-soluble coupler was used, it was added in the form of a 3% aqueous solution or an aqueous solution containing sodium hydroxide followed by neutralization with citric acid. In the case of an oil-soluble coupler, the coupler was dissolved in tricresyl phosphate in a conventional manner in a proportion of 5 g to 10 ml, dispersed in a 10% gelatin solution in the presence of an anionic surfactant such as sodium nonylbenzene sulfonate using ultrasonic wave agitation and a specific amount of the resulting dispersion was added. A coating aid (saponin) and a hardener (dichloro-5-hydroxytriazine) were added thereto. The resultant mixture was coated onto a transparent cellulose triacetate film and dried to obtain a desired light-sensitive material. The examples of the complete emulsions prepared are shown in Table 6 and those of the intermediate layers used in the invention are shown in Table 7. The multi-layer direct positive type light-sensitive materials of the invention were exposed to a tungsten light of 2854.degree.K through a filter and developed according to the object of its use.

TABLE 6 __________________________________________________________________________ Emul- Emulsion Used Electron Acceptor Color Coupler Remarks sion Type amount or Halogen Accep- Amount tor __________________________________________________________________________ (kg) (mol conc) (ml) a A 1 (a) (2 .times. 10.sup.-.sup.3) 80 -- FIG. 8 (m) (8 .times. 10.sup.-.sup.3) 40 b A 1 (a) (2 .times. 10.sup.-.sup.3) 80 -- FIG. 9 (n) (8 .times. 10.sup.-.sup.3) 40 c B 1 (o) (1.6.times.10.sup.-.sup.2) 40 -- FIG.10 d A 1 (q) (8 .times. 10.sup.-.sup.3) 160 C-3 (emulsion) 400 g FIG.11 e B 1 (t) (2 .times. 10.sup.-.sup.2) 50 C-1 (3% aque- ous alkaline FIG.12 soln) 200 ml f A 1 (m) (8 .times. 10.sup.-.sup.3) 40 C-4 (emulsion) 300 g FIG.13 (h) (2 .times. 10.sup.-.sup.3) 80 g A 1 (m) (8 .times. 10.sup.-.sup.3) 40 C-7 (3% aque- ous soln) FIG.14 200 ml (g) (1 .times. 10.sup.-.sup.3) 160 h B 1 (u) (8 .times. 10.sup.-.sup.3) 160 C-4 (emulsion) FIG.15 250 g i A 1 (m) (8 .times. 10.sup.-.sup.3) 40 C-9 (3% aque- FIG.16 ous soln) 200 ml (k) (5 .times. 10.sup.-.sup.4) 80 (1) (0.5% aqu- 80 eous solu- tion) j B 1 (v) (8 .times. 10.sup.-.sup.3) 160 C-12 (emul- FIG.17 sion) 200 g k C 1 (k) (5 .times. 10.sup.-4) 80 C-9 (3% aque- FIG.18 ous soln) 200 ml (1) (0.5% aqu- 80 eous solu- tion) __________________________________________________________________________

Table 7 __________________________________________________________________________ Complete Colloidal Solution Additives Solution __________________________________________________________________________ Type Amount m 7% gelatin 1 kg fine grain pure silver solution bromide grains (grain dia- meter 0.06 .mu.) 0.25 mol + 5% solution of sodium dibutylnaphthalenesulfonate 100 ml + (m) (8 .times. 10.sup.-.sup.3 mol) - 5 ml n 6% gelatin 1 kg yellow colloidal silver solution 0.07 mol + fine grain silver iodide grains 0.15 mol p 10% gelatin 1 kg negative silver chlorobromide solution light-sensitive grains 0.15 mol + (k) (0.5% alkali solution) 10 ml + C-7 (3% solution) 50 ml q 8% gelatin 1 kg 5% aqueous solution of solution polyvinyl-2-methylimidazole 200 ml + 10% aqueous solution of tartrazine 100 ml __________________________________________________________________________

Of the developing treatments, the black-and-white development was carried out according to the foregoing method, while the color development was carried out substantially according to the conventional developing method for developing color paper See L.F.A. Mason, Photographic Processing Chemistry, pages 153 - 155. The processings and solution compositions used are shown below:

1. Color Development 29.5.degree.C 6 min 2. Stop Fixing do. 2 do. 3. Water Washing (rinse) do. 2 do. 4. Bleaching do. 2 do. 5. Water Washing (rinse) do. 2 do. 6. Hardening Fixing do. 4 do. 7. Water Washing (rinse) do. 4 do. 8. Stabilizing Bath do. 2 do. 9. Drying Color Developer Composition Sodium Metaborate 25.0 g Sodium Sulfite 2.0 g Hydroxylamine (sulfate) 2.0 g Potassium Bromide 0.5 g 6-Nitrobenzimidazole (nitrate) 0.02 g Sodium Hydroxide 4.0 g Benzyl Alcohol 15.8 ml Diethylene Glycol 20.0 ml N-Ethyl-N-.beta.-(methanesulfon- amideethyl)-p-phenylenediamine 8.0 g Water to 1000 ml (pH = 10.6) Stop Fixing Solution Composition Ammonium Thiosulfate 120.0 g Sodium Metabisulfite 20.0 g Glacial Acetic Acid 10.0 g Water to 1000 ml (pH = 4.5) Bleaching Solution Composition Potassium Nitrate 25.0 g Potassium Ferricyanide 20.0 g Potassium Bromide 8.0 g Boric Acid 5.0 g Borax 2.5 g Water to 1000 ml (pH - 7.2) Hardening Fixing Solution Composition Ammonium Thiosulfate 120.0 g Sodium Sulfite 5.0 g Boric Acid 2.5 g Formalin (35-40%) 40.0 ml Water to 1000 ml (pH = 9.5)

Curve 1 of FIG. 19 is a characteristic curve obtained from the layer structure of FIG. 4 using Emulsion a for layer 2 and Complete Emulsion b for layer 3 through black-and-white development. Curve 2 is a characteristic curve of Emulsion b and Curve 3 is that of Emulsion a.

Curve 1 of FIG. 20 is a characteristic curve obtained from the layer structure of FIG. 4 using Emulsion a for layer 2 and Emulsion c for layer 3. Curve 2 is a characteristic curve obtained Emulsion c, while Curve 3 is a characteristic curve obtained, in the layer structure of FIG. 4, by coating Emulsion c as layer 2 and then coating Emulsion a as layer 3 thereonto.

FIG. 21 shows characteristic curves obtained by color development of a light-sensitive material produced using simultaneous multi-layer coating with Complete Solution m for the intermediate layer 5, Emulsion j for layer 2 and Emulsion h for layer 3 in the layer structure of FIG. 5. Curve 1 is a characteristic curve of the optical density (D.sub.G) obtained by measuring the density on exposure to green light and using a green filter, while Curve 2 is a characteristic curve of the optical density (D.sub.R) obtained by measuring the density on exposure to red light and using a red filter.

FIG. 22 shows characteristic curves obtained by color development of a light-sensitive material produced using simultaneous multi-layer coating with Emulsion i for layer 2 and Emulsion g for layer 4 without using intermediate layer 3 in the layer structure of FIG. 6. Curve 1 is a characteristic curve obtained by measuring the density on exposure to green and using a green filter, while Curve 2 is a characteristic curve obtained by measuring the density on exposure to red and using a red filter. Curve 3 is a characteristic curve obtained by splitting layer 2 into two layers, lowering the sensitivity of the lower layer by 50% and softening. The electron acceptor and halogen acceptor used are the same as those of Emulsion i.

FIG. 23 shows characteristic curves of a light-sensitive material composed of Complete Solution q or Complete Solution n containing yellow colloidal silver and superfine grain silver iodide for layer 5, Emulsion e composed of two layers for layer 6, Emulsion f for layer 4 and Emulsion k for layer 2. Curve 1 is obtained by subjecting to density measurement using a blue filter of a strip obtained by exposure to yellow light and color development. Curve 2 is obtained by subjecting to density measurement using a green filter of a strip obtained by exposure to green light and color development thereof. Curve 3 is obtained by subjecting to density measurement using a blue filter of a strip obtained by red exposure and color development. FIG. 24 are characteristic curves of a light-sensitive material composed of the use of Emulsion d for layer 6, Emulsion j for layer 2 and Emulsion j for layer 4 in the layer structure of FIG. 7. Curves 1, 2 and 3 are, respectively, similar to those illustrated about FIG. 23. In the case of a direct positive type color light-sensitive material used for obtaining FIG. 24, Complete Solution m containing superfine grain silver iodide and sodium dibutylnaphthalane sulfonate is used for intermediate layer 3 in the layer structure of FIG. 7 and the four layers of 2 to 5 are coated using the simultaneous multi-layer coating method.

Referring to FIG. 25, a direct positive-type multi-layer light-sensitive material is produced by using Emulsion k for layers 2 and 4 and Complete Solution p for layer 3 in the layer structure of FIG. 6 and further adding the following dye the material is then subjected to red light wedge exposure, followed by color development, to thus give a strip. The resulting strip is subjected to density measurement using a red filter or a green filter, obtaining Curves 1 and 2. It is evident from the results shown in FIG. 25 that a magenta-masked image of a direct cyan positive image can simultaneously be obtained by adapting the negative sensitivity of Complete Solution p.

Cyan Dye Used ##SPC14##

From the foregoing illustration the technical problems on formation of layers in the production of a direct positive-type light-sensitive material of at least two layers, the importance of the layer arrangement order in the direct positive-type emulsion, the importance of the presence of an intermediate layer, the importance of the use of the simultaneous multi-layer coating method and the marked effects and advantages of the present invention.

Claims

What is claimed is:

1. A direct positive-type multi-layer light-sensitive silver halide material having high information packing capacity comprising a support having thereon at least two emulsion layers selected from the group consisting of (A) a chemically fogged direct positive-type light-sensitive silver halide emulsion in which at least one of a halogen acceptor and an electron acceptor is adsorbed on the silver halide grains, and grains having free electron trapping nuclei therein, (B) a chemically fogged direct positive-type light-sensitive halide emulsion in which at least an electron acceptor is adsorbed on the silver halide grains, said grains being substantially free from positive hole trapping nuclei therein and (C) a chemically fogged direct positive-type light-sensitive silver halide emulsion in which at least a halogen acceptor is adsorbed on the silver halide grains, said grains having free electron trapping nuclei therein but being substantially free from positive hole trapping nuclei therein, said emulsions each having a different sensitized wavelength region, said emulsion layers being the same type emulsion layers or different type emulsion layers having therebetween an intermediate layer preventing diffusion or interaction of said electron acceptor or halogen acceptor between said emulsion layers, the halogen acceptor or electron acceptor in an emulsion layer differing from the halogen acceptor or electron acceptor in an emulsion layer sensitized to a different wavelength region, said intermediate layer illustrating substantially no desensitizing effect on said emulsion layers.

2. The direct positive-type multi-layer light-sensitive silver halide material of claim 1 wherein said material comprises at least two layers with an intermediate layer therebetween.

3. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two layers of the same type direct positive type light-sensitive silver halide emulsion selected from the group consisting of emulsion (A), emulsion (B) and emulsion (C).

4. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two layers in which neither a layer of emulsion (A) nor emulsion (C) is present on a layer of emulsion (B).

5. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two layers of different types of direct positive-type light-sensitive silver halide emulsions, said different types being emulsion (A) and emulsion (B) or emulsion (B) and emulsion (C), said layers being obtained by simultaneous multi-layer coating.

6. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two layers and where different type emulsion layers are present together an intermediate layer is contained therebetween.

7. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least three emulsion layers with at least one intermediate layer, said emulsion layers containing a blue-sensitive emulsion containing a yellow coupler, a green-sensitive emulsion containing a magenta coupler and a red-sensitive emulsion containing a cyan coupler.

8. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two adjacent emulsion layers of the same emulsion type but different in direct reversal sensitivity.

9. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two emulsion layers with an intermediate layer, said intermediate layer having incorporated therein a negative-type silver halide light-sensitive emulsion having a suitable spectral sensitivity and a corresponding amount of a color coupler whereby automatic masking of the unnecessary absorption of light by a direct positive image occurs.

10. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said halogen acceptor is a sensitizing dye of the M-band type in the 600 - 720 nm region.

11. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said halogen acceptor is a sensitizing dye having a cathodic polarographic half-wave potential more negative than -0.7 volts and wherein the difference between the cathodic polarographic half-wave potential and the anodic polarographic half-wave potential of said dye is greater than 1.5 volts.

12. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said electron acceptor is a desensitizing dye compound having a cathodic polarographic half-wave potential more positive than 1.0 volt.

13. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said halogen acceptor and said electron acceptor are each present in said emulsion at a level ranging from about 1 .times. 10.sup..sup.-6 to about 1 .times. 10.sup..sup.-3 mole per mole of silver halide.

14. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said intermediate layer comprises an emulsion layer having fine grain silver halide or silica therein.

15. The direct positive-type multi-layer light-sensitive silver halide material of claim 14, wherein said intermediate layer additionally contains a high molecular weight anionic organic compound or an anionic surface active agent.

16. The direct positive-type multi-layer light-sensitive silver halide material of claim 14, wherein said intermediate layer contains a color coupler whereby auto masking is provided.

17. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said electron acceptor is a compound selected from the group of compounds having the general formulas ##SPC15##

or ##SPC16##

wherein Z is an atomic group necessary for forming a heterocyclic ring, R is an alkyl group of 1 to about 6 carbon atoms or a substituted alkyl group, a and n each is 1 or 2 and X is an anionic group used conventionally for cyanine dyes. ##SPC17##

wherein Z.sub.3 is an atomic group necessary for forming a cycloheptatriene ring, Z.sub.1 is an oxygen atom, an --NH-- group or an --N= group, A is =0, a halogen atom or a pyrimidium group and B is a hydrogen atom, an alkoxycarbonyl group or an ##SPC18##

group, in which L.sub.1 and L.sub.2 are methine groups, Z.sub.2 is an atomic group necessary for forming a heterocyclic ring conventionally used for cyanine dyes, R is an alkyl or substituted alkyl group, X.sup.- is an anion conventionally used for forming cyanine dyes and m and n each is 1 or 2 and wherein said halogen acceptor is a compound selected from the group of compounds having general formulas ##SPC19##

wherein X.sub.1, X.sub.2, X.sub.3, X.sub.4 and X.sub.5 each is a hydrogen atom or a halogen atom, q is 1, 2, 3 or 4 and M is a hydrogen ion, an alkali metal ion or an ammonium ion. ##SPC20##

wherein Z.sub.4 and Z.sub.1 are atomic groups for forming heterocyclic rings used conventionally as cyanine dye nuclei, R and R.sub.1 each is an alkyl group, an allyl group or an aryl group, L.sub.1, L.sub.2 and L.sub.3 are methine groups, X.sub.1 is an anionic group used conventionally for cyanine dyes, p, q and m each is 1 or 2 and n is 1, 2 or 3.

18. The direct positive-type multi-layer light-sensitive silver halide material of claim 14, wherein said intermediate layer comprises an emulsion layer having fine grain silver halide.

19. The direct positive-type multi-layer light-sensitive silver halide material of claim 18, wherein said fine grain silver halide has a size less than about 0.2 microns.

20. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said intermediate layer comprises an emulsion layer having silica therein.

21. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said emulsion layers are different type emulsion layers.

22. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein emulsion (A) is capable of directly yielding a positive image without the electron acceptor or halogen acceptor.

23. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein emulsion (B) contains substantially no free electron trapping nuclei and is not capable of yielding a positive image without the electron acceptor, further wherein emulsion (B) is free from halogen acceptor.

24. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein emulsion (A) contains positive hole trapping nuclei.

25. The direct positive-type multi-layer light-sensitive silver halide material of claim 1, wherein said material comprises at least two layers of different types of direct positive-type light-sensitive silver halide emulsions, said different types being emulsion (A) and emulsion (C).

26. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a desensitizing dye compound having a cathodic polarographic half-wave potential more positive than 1.0 volt.

27. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a compound of general formula (Ia).

28. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a compound of general formula (Ib).

29. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a compound of general formula (II).

30. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a compound of general formula (III).

31. The direct positive-type multi-layer light-sensitive silver halide material of claim 17, wherein said electron acceptor is a compound of general formula (V).

32. The direct positive-type multi-layer light-sensitive silver halide material of claim 31, wherein Z.sub.4 and Z.sub.1 are selected from the group consisting of a naphthoxazole, indolenine, benzothiazole, .alpha.-naphthothiazole or quinoline nucleus.