Method of replenishing developing solution with replenisher

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FIELD OF THE INVENTION

The present invention relates to a method of replenishing a color developing solution with a developing replenisher in processing a silver halide color photographic material, and particularly to a method of replenishing a developing solution with a concentrated developing replenisher in a reduced amount.

BACKGROUND OF THE INVENTION

In recent years, higher efficiency and productivity have been in increasing demand for processing of color photographic materials. This tendency is particularly remarkable in the preparation of color prints, and a reduction in print processing time has been strongly desired to provide shorter finishing times.

A color print finishing stage generally comprises exposure and color development processing, and subsequent desilverization, washing and/or stabilization and drying.

The use of a highly sensitive photographic material results in a reduction in exposure time. On the other hand, in order to shorten the color development time, it is necessary to use, in combination, a photographic material capable of rapid development with a compatible processing solution or processing method.

Known techniques for solving such problems include processing a color photographic material containing an emulsion having a high silver chloride content (high silver chloride emulsion), in place of silver chlorobromide emulsions having a high silver bromide content and which have been widely used for photographic materials for color prints (color photographic paper). For example, PCT International Publication No. WO87/ 04534 discloses a method of rapidly processing color photographic paper comprising a high silver chloride emulsion with a color developing solution substantially free from sulfite ion and benzyl alcohol.

In addition to the above patent, JP-A-61-70552 (the term "JP-A" as used therein means an "unexamined published Japanese patent application") discloses a method for reducing the quantity of replenisher for a developing solution, in which the replenisher is added in an amount such that there is no overflow of the developing bath during development, using a high silver chloride content color photographic material. Furthermore, JP-A-63-106655 discloses a method of processing a high silver chloride content color photographic material with a color developing solution containing a hydroxylamine compound and chloride ion at a specific minimum concentration to provide stable processing.

Thus, by use of a high silver chloride content emulsion or by adapting the developing solution, the development time can be shortened from 3.5 minutes (for example, color processing CP-20, Fuji Photo Film Co., Ltd.) to 45 seconds (for example, color processing CP-40FAS, Fuji Photo Film Co., Ltd., total processing time: 4 minutes).

The development function can be renewed by replenishing a developing solution with a developing replenisher depending on the consumption or deterioration state of the developing solution. In general, the developing solution is replenished with a developing replenisher containing a developing agent, a preservative, a chelating agent, a salt, an alkaline component and the like all in the same one solution, depending on the quantity of photographic material to be processed.

However, the solubility of the developing agent in a high pH replenisher solution containing the preservative or the alkaline component is less than the solubility in a low pH solution such as a neutral or acidic solution. As a result, it is difficult to prepare a highly concentrated replenisher solution. For this reason, when the developing solution must be replenished with a large amount of the developing agent, the replenishment rate must be increased. Accordingly, an increased amount of waste liquid overflows from the developing tank.

In recent years, it has been desired to reduce or prevent the generation of waste liquid in photographic processing, due to the complexity of treatment needed to make the photographic processing waste liquid environmentally sound. Also, when the developing solution is replenished, the concentration of the developing agent in the developing replenisher is conceivably raised to reduce the replenishment rate such that the developing solution does not overflow. However, it is difficult to increase the amount of the developing agent dissolved in solution as long as the developing replenisher contains high pH components such as the alkaline component.

Recently, the rapid processing of color photographic paper which does not generate polluting waste liquid has been desired. Accordingly, investigators have sought to reduce the replenishment rate of color developing solutions as applied to rapid processing of color photographic paper using silver halide emulsions containing 90 mol % or more of silver chloride, to thereby reduce the waste liquid amount of the color developing solution containing a large quantity of harmful substances. For this purpose, it has been proposed to separately replenish the developing solution with a low pH replenisher mainly containing a color developing agent and a high pH replenisher containing components other than the color developing agent, such that the concentration of the color developing agents can be increased in the low pH replenisher. The replenishment rate can therefore be reduced, which results in the discharge of little or no waste liquid.

The developing solution is replenished with such a replenisher, depending on the quantity of photographic material to be processed, the pH of the developing solution, the change in solution amount due to evaporation, and the change in composition due to air oxidation. When the developing solution is replenished by concurrently admixing the low pH replenisher or concentrated developing solution and the high pH replenisher containing components other than the developing agent, a precipitate results which not only lowers the replenishment function, but also introduces the problem of treating the precipitate.

Furthermore, it has been found that the developing agent in the low pH replenisher gradually deteriorates during long storage and adversely affects photographic images.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to solve the above-described problems, and to provide a method for replenishing a developing solution with a small amount of a developing replenisher without the formation of a precipitate, which developing solution is well adapted to rapid processing of color photographic paper.

Another object of the invention is to provide a method for replenishing a developing solution with a developing replenisher which has a low pH sufficient to make it possible to prepare a concentrated solution of a developing agent and which has an excellent long storability and does not cause any decrease in photographic sensitivity and any increase in the minimum density of a photographic image.

The above objects of the present invention are attained by providing a method for processing an imagewise exposed color photographic material comprising a support having thereon at least one light-sensitive silver halide emulsion layer comprising a silver halide emulsion containing at least 90 mol % silver chloride, comprising the steps of: (a) developing in a color developing bath; (b) bleaching in a bath having a bleaching ability and fixing in a bath having a fixing ability or bleach-fixing in a bath having a bleaching and fixing ability; and (c) independently supplying a low pH replenisher and a high pH replenisher to the developing bath each in an amount depending on the quantity of photographic material processed, said low pH replenisher having a pH of from 2 to 6 and mainly containing a color developing agent and said high pH replenisher containing one or more components of the developing bath, wherein the components of each replenisher are sufficiently diluted upon addition to the developing bath to avoid formation of a precipitate by mixing with the components of the unlike replenisher.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a device for replenishing a developing bath for use in the present invention; and

FIG. 2 is a schematic view showing an apparatus for processing photographic materials for use in the present invention.

DETAILED DESCRIPTION OF THE INVENTION

When the developing solution is replenished by independently supplying thereto a low pH replenisher and a high pH replenisher in accordance with the present invention, the components of each replenisher are sufficiently diluted upon addition to the developing bath to avoid the formation of a precipitate by mixing with the components of the other unlike replenisher. When simultaneously added to the developing bath, the points for addition of each of the unlike replenishers are positioned sufficiently apart from one another as to not form a precipitate. For example, separate pipes may be used to simultaneously supply each of the low pH replenisher and the high pH replenisher to the developing bath, where the points for addition of the replenishers to the developing bath are sufficiently positioned apart from another as to not form a precipitate. Also in accordance with the present invention, the low pH replenisher and high pH replenisher may each be supplied to the developing bath at different (staggered) time intervals through the same pipe or through separate pipes. An appropriate combination of staggered time intervals for addition and positioning of the supply pipes may also be employed. Methods of adding each of the replenishers at a distance include adding the replenishers to the developing bath through nozzles located apart from one another, and adding one replenisher below the liquid surface level of the developing bath and the other replenisher at the liquid surface of the developing bath.

In view of precipitation on the inner surface of the supply pipes (particularly in the case of a long operation period) it is most preferred to add the low pH replenisher and the higher pH replenisher to the developing bath through separate pipes.

Also in accordance with a preferred embodiment of the invention, one replenisher is diluted at least two fold in concentration in the developing bath before adding the other unlike replenisher.

Furthermore, the low pH replenisher for use in the present invention preferably contains a sulfinic acid or a salt thereof and has a pH of from 2 to 6. This is effective in stabilizing the low pH replenisher containing the developing agent in a high concentration during long storage.

The low pH replenisher for use in the present invention preferably contains 0.05 mol/l or more of a color developing agent.

It is also preferred that the low pH replenisher and the high pH replenisher are rapidly mixed in the developing bath and that in order to make the replenishment device simple and small both replenishers are supplied to the developing bath alternately (if necessary at different time intervals) at the same level of the developing bath.

The solution circulation rate in the developing solution may be 1 l/min, and preferably from 4 to 24 l/min, in order to instantaneously mix each replenisher in the tank solution.

The tank capacity is preferably small and is preferably up to 20 l, particularly preferably up to 5 l.

The inside diameter of the replenisher supply pipe may be from 1 to 10 mm, and preferably from 2 to 5 mm.

For preventing the formation of precipitates due to the mixing of each concentrated replenisher it is preferred that the replenisher supply pipes are located apart from one another by five times or more, and preferably 10 times or more the inside diameter of the pipe.

When the pipes are placed in a vertical direction it is preferred that at least one pipe is positioned at a vertical distance of one third of the depth of the developing solution below the surface level.

When the replenishers are each supplied to the developing bath at different (staggered) time intervals, the a staggered time intervals are preferably from 1/60 to 1/1200 of the value of tank capacity (liter)/solution circulation rate (l/min) because the mixing of the initially supplied replenisher in the tank solution largely depends on the tank capacity and the solution circulation rate.

In the present invention, the developing replenisher comprises at least a low pH replenisher mainly containing a color developing agent and a high pH replenisher containing one or more components of the developing solution preferably other than the developing agent. Furthermore, a large amount of the developing agent can be dissolved in the low pH replenisher. Accordingly, the low pH replenisher for replenishing the developing agent has a high developing agent concentration, and the development function can be recovered by supplying a small amount of the replenisher to the developing bath. Furthermore, the developing solution is also replenished with the high pH replenisher containing replenishing components, based on the pH of the developing solution, such that the pH of the developing solution is maintained sufficiently high by replenishing a small amount of the replenisher.

According to the present invention the developing replenisher is divided into two replenishers having different pH values and the two replenishers are added separately so that they are not mixed before being supplied. A method comprising supplying only a high pH solution in use has been widely used for supplying a replenisher.

The pH of the replenisher has not been lowered previously, because such a step is considered to have the disadvantage of making the process complicated.

On the other hand, although the solubility of the developing agent in solution is remarkably increased at a pH of 6 or less, it has been found that in an open system the developing agent gradually deteriorates with time and that particularly it is not preferred to store the developing agent in solution for long.

When the replenishment processing is carried out by using a long-stored replenisher, the increase in the minimum density (Dmin) of a photographic image and the decrease in sensitivity have occurred in correspondence to the deterioration degree of the developing agent.

In the present invention, therefore, it has become necessary to prevent the deterioration of and improve the stability of the developing agent in the replenisher at a pH of 6 or less.

Also on this point the present inventors have made extensive studies to find that the use in the low pH replenisher of a compound capable of scavenging the oxidation product of the developing agent in the range of the pH claimed in the present invention, makes it possible to prevent the deterioration of the developing agent and to inhibit the occurrence of tar-like products formed as a result of the deterioration of the developing agent. Sulfites are well known compounds that react with the oxidation products of hydroquinones and p-phenylenediamine derivatives. However, when the high-silver chloride content, color photographic material is processed by color development in the present invention, the use of a sulfite is not desirable because the solubility of the silver salt in a high content and the coloring efficiency are lowered.

The present inventors have found that when a sulfinic acid or a salt thereof which is described as compounds capable of reacting with the oxidation product of the developing agent in The Chemistry of Quinoid Compounds, Vol. II, Chap. 21 is incorporated into the low pH replenisher, the deterioration of the developing agent in an open system is greatly inhibited. Also, unlike sulfites, a sulfinic acid and a salt thereof are desirable because they have no adverse effects on the developability in color development and do not reduce coloring efficiency.

The present invention has made it possible to store the replenisher in a high concentration and in a stable condition for a long time, to handle the replenisher in an open system and to replenish the developing solution with the low pH and high pH replenishers used separately without simultaneously by mixing the two replenishers.

JP-A-1-230039 describes that particularly, a sulfinic acid or a salt thereof improves the stability of the bleach-fixing solution, fixing solution, a washing process and a stabilization process and is used in the processing steps for photographic materials in order to prevent the occurrence of stains. However, JP-A-1-230039 does not suggest the prevention of the deterioration of the developing agent in such a low pH replenisher as used in the present invention. Also, JP-A-1-230039 does not suggest that a small amount of the long-stored replenisher can prevent the decrease in photographic sensitivity and inhibit the increase in Dmin.

Examples of the components which may be contained in the high pH replenisher for use in the present invention include a buffer, an alkaline agent, (a chelating agent), (an antifogging agent), a fluorescent brightening agent, (a surface active agent), (a development accelerator), a small amount of a color developing agent, (a preservative) and a water-soluble polymer, wherein the color developing agent is contained at a concentration of 1/10 or less, and preferably at a concentration of 1/100 or less the concentration of the developing agent in the low pH replenisher. Components which may be contained in the low pH replenisher include (a chelating agent), (an antifogging agent), (a surface active agent), (a development accelerator), (a preservative), and (a water-soluble polymer) as well as a color developing agent. For lowering the pH of the low pH replenisher, the color developing agent is preferably used in the form of an acid salt such as a sulfate.

The above-described components designated in parentheses may be separately added to the indicated replenisher only, or may be added to any of the low or high pH replenishers without adverse effect.

Specific compounds thereof are described below.

The pH of the low pH replenisher containing the developing agent is preferably 2 to 6, and more preferably 3 to 5. The amount of the color developing agent contained in the low pH replenisher is 0.05 mol/l or more, and preferably in the range from 0.1 mol/l to 0.6 mol/l.

The pH of the high pH replenisher containing replenishing components for the color developing solution other than the developing agent is 9 or more, preferably 10 or more, and more preferably in the range from 12 to 14.

The color photographic material (color photographic paper) for use in the present invention can comprise a support having thereon at least one each of a blue-sensitive, green-sensitive and red-sensitive silver halide emulsion layer. For ordinary color photographic paper, the red-sensitive silver halide emulsion layer is usually arranged closest to the support; however, the arrangement order may be modified depending on the intended application.

Known image forming systems for rapid processing of color photographic paper are generally applicable to the present invention, and can also be used for intelligent color hard copying which requires even faster processing.

In particular, a preferred embodiment of intelligent color hard copying comprises scanning exposure using a high density light such as light emitted by a laser (for example, a semiconductor laser) or a light emitting diode.

The semiconductor laser light emits radiation in the infrared region in many cases, and therefore an infrared-sensitive silver halide emulsion layer can be used in place of one of the above-described emulsion layers sensitive to visible light in the photographic material for use in the present invention. As used herein, "light-sensitive" includes sensitivity to both visible and infrared light. Each of the sensitive emulsion layers generally contains a silver halide emulsion having sensitivity to a particular wavelength region and a dye complementary to light to which the emulsion layer is sensitive. Namely, a color coupler forming a yellow image is used in a blue-sensitive silver halide emulsion layer, a magenta forming coupler is used in a green-sensitive layer, while a cyan forming coupler is used in a red-sensitive layer, to allow for a subtractive color process. However, the sensitive emulsion layers and color couplers may be combined to correspond in a manner different from that described above.

Furthermore, depending on the desired image quality and other considerations, the color coupler may form two colors. In this case, two silver halide emulsion layers may be used corresponding to the respective colors. Although full color images are not formed in this case, it is possible to form images more rapidly.

The silver halide emulsion for use in the present invention comprises silver chlorobromide containing at least 90 mol % silver chloride or comprises silver chloride. Grains constituting the emulsion may be the same or different from one another in terms of halogen composition. However, when the grains constituting the emulsion each have the same halogen composition, uniform properties of each grain is readily achieved. With respect to the internal halogen composition distribution of the silver halide grains, a uniform type structure in which the composition is the same at any portion of the grain, a laminated type structure in which the halogen composition of the internal core of the grain is different from that of the surrounding shell (one layer or a plurality of layers), or a structure in which the inside of the grain or the surface thereof has non-layer portions differing in halogen composition (e.g., a structure in which the portions different in halogen composition are connected to the edges, the corners or the surface of the grain when on the surface of the grain) may be used. In order to obtain high sensitivity, it is more advantageous to use either of the latter two grains types as opposed to grains having a uniform structure. The latter two non-uniform grains are also preferable with respect to pressure resistance. When the silver halide grains have a structure as described above, the boundary between portions having a different halogen composition may be distinct, or may be obscured by the formation of mixed crystals resulting from the difference in composition. Further, a continuous change in structure may also be imparted to the silver halide grains.

On the other hand, to minimize the reduction in sensitivity when pressure is applied to the photographic material, grains having a uniform structure in which the halogen composition distribution within the grain is small are preferably used in the high silver chloride emulsion of the present invention containing at least 90 mol % silver chloride.

Furthermore, for reducing the quantity of replenisher to a developing solution, it is also effective to increase the silver chloride content of the silver halide emulsion. In this case, an emulsion containing almost pure silver chloride such that the silver chloride content thereof is 98 to 100 mol % is preferably used.

The silver halide grains contained in the silver halide emulsion for use in the present invention preferably have a mean grain size of 0.1 to 2 .mu.m. The mean grain size is a number mean value of grain sizes represented by the diameters of circles having areas equivalent to the projected areas of the grains.

Furthermore, the emulsion for use in the present invention is preferably a monodisperse emulsion having a narrow grain size distribution; namely, a coefficient of variation (the standard deviation of the grain size distribution divided by the mean grain size) of not more than 20%, desirably not more than 15%. For the purpose of obtaining a wide latitude, the above-described monodisperse emulsions can be blended in the same layer, or may be coated in the form of multiple layers.

The silver halide grains contained in the photographic emulsion may have a regular crystal form such as a cubic, an octahedral or a tetradecahedral form, an irregular crystal form such as a spherical form or a plate (tabular) form, or a composite form thereof. Furthermore, a mixture of grains having various crystal forms may also be used. In the present invention, the emulsion preferably contains at least 50%, preferably at least 70% and more preferably at least 90% of the above-described grains having a regular crystal form.

Aside from the above, a tabular emulsion can also be used, wherein more than 50% of all grains on a projected area basis are tabular grains having a mean aspect ratio (a ratio of diameter calculated as a circle/thickness) of at least 5 and preferably at least 8.

In order to improve image sharpness, the hydrophilic colloid layer of the photographic material of the present invention preferably contains a dye which is discolored upon processing (particularly an oxonol dye) as described at pages 27 to 76 of European Patent EP 0,337,490A2, to provide an optical reflection density of 0.70 or more at 680 nm. The water-resistant resin layer of the support of the photographic material of the present invention preferably also contains at least 12% by weight (more preferably, at least 14% by weight) titanium oxide surface treated with a divalent to tetravalent alcohol (for example, trimethylolethane).

In the photographic material of the present invention, compounds for improving the storage quality of color images as described in European Patent EP 0,277,589A2 are preferably used in combination with the couplers. In particular, they are preferably used in combination with pyrazoloazole couplers.

In order to prevent the generation of stains and other undesirable effects due to formation of an unwanted dye by reaction of residual color developing agent or an oxidation product thereof with a coupler during storage after processing, the compound (F) and or (a) are preferably incorporated into the photographic material. The compound (F) chemically bonds to aromatic amine developing agent remaining after color development to form a chemically inactive, substantially colorless compound. The compound (G) chemically bonds to an oxidation product of the aromatic amine color developing agent remaining after color development to form a chemically inactive, substantially colorless compound. The compounds (F) and (G) may be used alone or in combination. The compounds (F) and (G) are described in JP-A-62-283338, JP-A-62-229145 and JP-A-3-229246 and used in an amount, per mol of a coupler, of preferably from 1.times.10.sup.-2 to 10 mol, more preferably from 3.times.10.sup.-2 to 5 mol.

Furthermore, an antifungal agent as described in JP-A-63-271247 is preferably added to the photographic material of the present invention to prevent images deterioration by the proliferation of various molds and bacteria in the hydrophilic colloidal layers.

A white polyester support or a support provided with a white pigment-containing layer on the emulsion layer side thereof may be used in a photographic material for display of the present invention. Furthermore, in order to improve sharpness, an antihalation layer is preferably formed on the side coated with a silver halide emulsion layer or on the back surface of the support. In particular, the transmission density is preferably adjusted within the range of 0.35 to 0.8 such that the display can be appreciated with both reflected light and transmitted light.

The photographic material of the present invention may be exposed to visible light or infrared light. The exposure may comprise either low illuminance exposure or high illumination exposure for a short time period. In particular, in the latter case, a laser scanning exposure method in which the exposure time per picture element is shorter than 10.sup.-4 second is preferred.

For exposure, the band stop filter described in U.S. Pat. No. 4,880,726 is preferably used, such that optical color mixing is eliminated and color reproducibility is markedly improved.

The exposed photographic material is generally subjected to color development. Bleach-fixing is preferably conducted after color development for rapid processing. In particular, when the above-described high silver chloride emulsion is used, the pH of the bleach-fixing solution is preferably about 6.5 or less, and more preferably about 6 or less to enhance desilverization.

Preferred silver halide emulsions, additives and photographic constituent layer structure (such as layer arrangement) which may be applied to the photographic material of the present invention, and processing methods and additives for processing compositions for use in the present invention, are described in the following patents shown in Table A, particularly in European Patent EP 0,355,660A2 (Japanese Patent Application No. 1-107011).

TABLE A __________________________________________________________________________ Photographic Constituents, etc. JP-A-62-215272 JP-A-2-33144 EP 0,355,660A2 __________________________________________________________________________ Silver Halide Page 12, lower -- -- Emulsions left column, lines 6 to 14; page 13, upper left column, line 3 from the bottom to page 18, lower left column, the last line Chemical Page 12, lower Page 29, lower Page 47, Sensitizers left column, right column, lines 4 to 9 line 3 from line 12 to the the bottom to last line lower right column, line 5 from the bottom; page 18, lower right column, line 1, to page 22, upper right column, line 9 from the bottom Spectral Page 22, upper Page 30, upper Page 47, Sensitizers right column, left column, lines 10 to (Spectrally line 8 from the lines 1 to 13 15 Sensitizing bottom to page Methods) 38, the last line Emulsion Page 39, upper Page 30, upper Page 47, Stabilizers left column, left column, lines 16 to line 1 to page line 14 to 19 72, upper right upper right column, the column, line 1 last line Development Page 72, lower -- -- Accelerators left column, line 1 to page 91, upper right column, line 3 Color Couplers Page 91, upper Page 3, upper Page 4, lines (Cyan, Magenta, right column, right column, 15 to 27; Yellow Cou- line 4 to page line 14 to page 5, line plers) 121, upper page 18, upper 30 to page 28, left column, left column, the last line; line 6 the last line; page 45, lines page 30, upper 29 to 31; right column, page 47, line line 6 to page 23 to page 63, 35, lower line 50 right column, line 11 Color Develop- Page 121, upper -- -- ment Increas- left column, ing Agents line 7 to page 125, upper right column, line 1 Ultraviolet Page 125, upper Page 37, lower Page 65, Absorbers right column, right column, lines 22 to line 2 to page line 14 to 31 127, lower left page 38, upper column, the left column, last line line 11 Antifading Page 127, lower Page 36, upper Page 4, line Agents right column, right column, 30 to page 5, (Image Stabi- line 1 to page line 12 to line 23; page lizers) 137, lower left page 37, upper 29, line 1 to column, line 8 left column, page 45, line line 19 25; page 45, lines 33 to 40; page 65, lines 2 to line 21 High Boiling Page 137, lower Page 35, lower Page 64, and/or Low left column, right column, lines 1 to 51 Boiling line 9 to page line 14 to Organic 144, upper page 36, upper Solvents right column, left column, the last line line 4 from the bottom Methods for Page 144, lower Page 27, lower Page 63, line Dispersing left column,