US3585032A

US3585032A - Production of colored photographic images by the silver dye bleach process

Info

Publication number: US3585032A
Application number: US809407A
Authority: US
Inventors: Erich Bockly; Justus Danhauser; Max Heilmann; Johannes Gotze; Eberhard Gunther
Original assignee: Agfa Gevaert AG
Current assignee: Agfa Gevaert AG
Priority date: 1968-04-04
Filing date: 1969-03-21
Publication date: 1971-06-15
Anticipated expiration: 1988-06-15
Also published as: GB1253892A; BE730611A; CH528100A; DE1772137A1; FR2005559A1

Abstract

SILVER DYE BLEACHING PROCESS UTILIZING SILVER HALIDE EMULSIONS IN WHICH THE MOLAR RATIO OF SILVER TO THE BLEACHABLE AZO GROUPS OF THE AZO DYE IS AT LEAST 12 TO 1 AND DEVELOPMENT IS CARRIED OUT WITH A DEVELOPER OF THE P-PHENYLENEDIAMINE SERIES HAVING A HIGH SULFITE CONTENT. THIS INVENTION RELATES TO A PHOTOGRAPHIC MATERIAL AND TO A PROCESS FOR THE PRODUCTION OF COLORED PHOTOGRAPHIC IMAGES BY THE SILVER DYE BLEACHING PROCESS. IT IS KNOWN TO PRODUCE COLORED PHOTOGRAPHIC IMAGES BY THE SILVER DYE PROCESS. IN THIS PROCESS, THE DYE (OR DYES IN THE CASE OF A MULTI-LAYERED MATERIAL), WHICH IS USUALLY AN AZO DYE, IN A HOMOGENEOUSLY DYED COLLOIDAL LAYER IS BLEACHED IMAGEWISE IN A STRONGLY ACID BATH IN THOSE AREAS OF THE LAYER WHERE A SILVER IMAGE HAS PREVIOUSLY BEEN PRODUCED.

Description

United States Patent 01 hoe Patented June 15, 1971 PRODUCTION oF coLoREi) PHOTO-GRAPHIC IMAGES BY THE SILVER DYE BLEACH PROCESS Erich Bockly, Leverkusen, Justus Danhiiuser, Cologne- Stammheim, Max Heilmann, Cologne-Flittard, Johannes Giitze, Bergisch-Neukirchen, and Eberhard Giinther, Leverkusen, Germany, assignors to Agfa-Gevaert Aktiengesellschaft, Leverkusen, Germany N Drawing. Filed Mar. 21, 1969, Ser. No. 809,407 Claims priority, application Germany, Apr. 4, 1968,

P 17 72 137.8 Int. Cl. G03c 7/00 U.S. Cl. 96-53 3 Claims ABSTRACT OF THE DISCLOSURE Silver dye bleaching process utilizing silver halide emulsions in which the molar ratio of silver to the bleachable azo groups of the azo dye is at least 12 to l and development is carried out with a developer of the p-phenylenediamine series having a high sulfite content.

This invention relates to a photographic material and to a process for the production of colored photographic images by the silver dye bleaching process.

It is known to produce colored photographic images by the silver dye bleaching process. In this process, the dye (or dyes in the case of a multi-layered material), which is usually an azo dye, in a homogeneously dyed colloidal layer is bleached imagewise in a strongly acid bath in those areas of the layer Where a silver image has previously been produced.

Both negative and reversal images can be produced by this process. If positive images on paper or duplicate positives are to be produced directly from diapositives, a simple black-and-white development is used to produce a silver image which is then a negative of the original used for copying. Since the dye which is homogeneously distributed in the layer (or in three layers when using a multi-colored material) is destroyed to the extent that the silver image is formed, the required dye image re versal image) which is a positive of the original is finally obtained. If a silver image, i.e. a silver reversal image, which is a positive of the original is produced, e.g.. by a black-and-white reversal development or by means of the bromine ion diffusion process, a dye image which is 0pposite in gradation to the original is produced after bleaching of the dye, i.e. a positive color image if the original is a color negative.

Considerable diificulties arise in producing colored images by the silver dye bleaching process which have a suificiently fine dye grain and sufliciently low gradation.

Another disadvantage of the silver dye bleaching proc ess is that the azo dyes contained in the silver halide emulsion layers absorb light of the particular wavelength region to which the silver halide is sensitive. Hence the sensitivity of the layers is greatly reduced. For this reason, the known materials for uese in the silver dye bleaching process are only suitable for use as copying materials and even when used for this purpose they are inferior to the conventional photographic copying materials.

It is an object of the invention to modify the silver dye bleaching process by choosing certain silver halide emulsions and making variations of the process so that colored images which have a fine grain and low gradation can be obtained and so that a very high sensitivity of the silver halide emulsion layer is also obtained.

It has now been found that emulsions in which the molar ratio of silver (in the form of silver halide) to the bleachable azo groups of the azo dye is at least 12:1 and which are developed with a developer of the phenylene diamine series at relatively high sulfite concentrations are particulary suitable as photographic materials for use in the silver dye bleaching process.

It is desirable to use highly sensitive silver iodobromide gelatine emulsions. The ratio of silver to azo bond according to the invention of 12:1 is far greater than the quantity of silver required for bleaching an azo bond according to the following equation:

The highly sensitive emulsions contain at least g. of silver, in the form of silver halide, per kg. of crude emulsion. It is especially preferred to use emulsions which have silver contents of to 30 of silver per kg. of crude emulsion, which corresponds to a silver dye ratio of about 16:1 to about :1 per azo bond, depending on the molecular weight of the azo dye used.

Development is carried out with a color forming developer of the p-phenylenediamine series, preferably one of the following: N,N-diethyl-p-phenylenediamine, compounds according to German patent specification 965,617, 4-(N,N-diethylamino)-2-rnethylaniline or 4- (N-ethyl-N- methyl-sulfarnidoethyl-amino)-2-methylaniline. The con centration is generally between 0.5 and 25 g. per litre of developer solution, preferably between 2 g. and 15 g. per litre.

The sulfite content of the developer solution is substantially higher than that of the developing compositions conventionally used for the color-forming development of color materials which have color couplers incorporated. Thus, instead of using'2.5 to 4.0 g. per litre, amounts of about 15 to 60 g. of sulfite are used per 1 litre of solution; it is preferred to use 20 to g. These sulfite contents are very unusual and are undesirable when used for processing conventional color photographic materials (see the article by K. Meyer, Bild und Ton (1954) page 72).

If the silver dye bleaching materials described above are developed in a conventional black-and-white developer after exposure and then processed in the same manner, the gradations obtained with such an excess of silver halide are much too high and the dye grain is much coarser. The materials according to the invention are prepared in the usual manner. They are preferably cast on supports which have a very smooth surface, e.g. pigmented cellulose acetate foils.

The silver halide emulsion layers may be optically and chemically sensitized in known manner. They may contain the known azo dyes, e.g. those described in the following German Pats. 1,284,299; 1,285,308; German patent specification P/15/22/354.8; French Pat. 1,521,171; British Pat. 1,146,406; Italian Pat. 799,402; French Pat. 1,521,909; Italian Pat. 800,306; Belgian Pat. 697,727; French Pat. 1,543,001; Belgian Pat. 715,411; Belgian Pat. 717,207.

The layers may also be stabilized in known manner. They may contain the known plasticizers, wetting agents or hardeners.

After development, processing is carried out in known manner.

EXAMPLE 1 A silver dye bleaching material according to the invention is prepared and processed as follows:

parts of a 1% aqueous solution of 6-methyl-4-hydroxy-l,3,3a,7-tetraazaindene, 30 parts of a 0.1% methanolic solution of a red sensitizer according to German 3 Auslegeschrift 1,213,240 (Example 11), 250 parts of a 2% aqueous solution of the blue-green dye:

50 parts of a 7.5% aqueous solution of saponin and parts of a 5% methanolic solution of N,N',N-tris(acryloyl)-perhydrotriazine-l,3,5 are added successively with stirring at 40 C. into 1000 parts of highly sensitive silver idodobromide emulsion consisting of 8% of gelatin and in which the amount of silver halide present is equivalent to 2.6% of silver, 6% of which is in the form of silver iodide. The molar ratio of silver to azo bonds is in this case :1 instead of the theoretical ratio of 4:1 based on the bleaching reaction of one azo bond.

The red sensitive emulsion produced in this way is applied to a support of prepared white pigmented cellulose acetate in such a thickness that the layer obtained after drying contains 1.0 g. of silver, in the form of silver halide, per square metre.

Samples of the resulting material are exposed behind a red filter and a grey step wedge which has a logarithmic density increase of 0.10, and then processed as follows:

(1) Develop 8 minutes in a bath of:

G. N,N-n-butyl-n-w-sulfobutylphenylenediamine 6 Hydroxylamine sulfate 4 K Sodium sulfite Potassium bromide 1 Sodium carbonate 100 dissolved in water to make up 1,000 m1.

(2) Wash 5 minutes. (3) Harden: 5 minutes in a bath of:

Formalin aqueous solution)70 ml. Sodium bicarbonate-5 g. Water up to 1,000 ml.

(4) Wash 5 minutes. Bleach dye 15 minutes in a bath of:

Quinoline ml.

Sodium hypophosphite-5 g. Potassium iodide-10 g. Sulfuric acid conc.75 ml. Water up to 1,000 ml.

(6) Wash 5 minutes. (7) Bleach-fix 15 minutes in a bath of:

G. Sodium carbonate anhydrous 24 Sodium thiosulfate anhydrous 125 Tetrasodium ethylenediaminotetraacetate 26 Ferric chloride 15 Sodium sulfite anhydrous 13 Water up to 1,000 ml.

(8) Wash 10 minutes.

Sensitometric tests on the resulting dye wedge gives a 7 value of 0.9 at the maximum density of 1.95. No dye graininess was found on subjective viewing of the blue-green dye wedge. Increasing the length of time in the dye bleaching bath 5 does not alter the given sensitometric values.

If the same material is exposed in the same manner and developed for 5, 4, 3, 2 or 1 minutes in a conventional p-methylaminophenol-hydroquinone developer of the following composition:

G. p-Methylarninophenol 1 Hydroquinone 3 Sodium carbonate anhydrous 26 Sodium sulfite 13 Potassium bromide 1 Water up to 1,000 ml.

and then treated in baths 2 to 8 as described above, the dye wedges obtained have 7 values of 3.5, 3.5, 3.5, 3.2 and 2.4 and maximum densities of 1.68, 1.77, 1.82, 1.88 and 1.92 and very coarse dye grains.

If the developer mentioned under (la) is diluted 1:1 with distilled water (developer (lb)) and the material which has been exposed in the same manner is developed in this developer for 5, 4, 3, 2 and 1 minutes and then treated in baths 2 to 8, maximum color densities of 1.90, 1.90 and 1.91 and 7 values of 3.1, 3.1 and 2.6 are obtained after 5, 4 and 3 minutes development time, respectively. The wedges obtained after 2 minutes and 1 minute development cannot be evaluated owing to incomplete bleaching. The dye graininess is again distinctly coarser than when using the color wedge obtained with developer 1.

In a further experiment, samples of material described are developed in each case for 10 minutes at 20 C. in developers I to V after exposure as described above. The developer solutions are obtained from the same basic recipe and contain equimolar quantities of different pphenylenediamine derivatives. The samples are, after development, treated in baths 2 to 8 for the same lengths of time as given above, the maximum color densities and '7 values shown in Table 1 are obtained. Practically no dye graininess can be found in any case on subjective viewing with the naked eye.

Basic solution: G. Sodium salt of ethylenediaminotetraacetate 5 Sodium sulfite anhydrous 20 Trisodium phosphate 10 Potassium bromide 1 Water up to 1,000 ml.

TABLE 1 Maximum color density 7 Value Developer:

I 1. 06 l. 0 II 1. 0.8 III 1.07 0.7 IV 2. 02 0.8 V 1.83 1. 3

Example 2 40 parts of a 1% aqueous solution of 6-methyl-4-hydroxy-l,3,3a,7-tetraazaindene, 40 parts of a 0.1% methanolic solution of green sensitizer 16 given in French Pat. 1,531,154 and Belgian Pat. 700,720, 200 parts of a 2% aqueous solution of the magenta dye of the formula:

30 parts of a 7.5% aqueous solution of saponin and 10 parts of a methanolic solution of N,N',N-tris- (acryloyl)perhydrotriazine-l,3,5 are successively stirred, at 40 0., into 1,000 parts of a highly sensitive silver iodobromide emulsion which consists of 80 parts of gelatin and 23 parts of silver, in the form of silver halide, of which 6 mols percent is in the form of silver iodide. The ratio of silver to azo bonds is in this case 29:1.

The green sensitive emulsion prepared in this way is applied to the support described in Example 1 in such a manner that the layer obtained after drying contains 0.90 g. of silver per square metre. Samples of the resulting material are exposed behind a green filter and a grey step wedge which has a logarithmic density increase of 0.10, and they are then treated in baths 1 to 8 as given in Example 1 and dried.

Sensitometric determination of the resulting magenta step wedge showed an average maximum color density of 1.3 and a 7 value of 0.95. Again, practically no dye graininess can be seen on subjective viewing with the naked eye.

If the same material is exposed in the same manner and developed for 5 minutes and 1 minute, respectively, in the p-methylaminophenol-hydroquinone developer given under 1a and then processed as described in Example 1, the following figures are obtained:

TABLE 2 Maximum Development eolor time densities 7 Value Minutes Here again a distinct dye graininess is found.

If samples of the same material are exposed in the same manner and developed in each case for minutes in developers I to V as described in Example 1 and processed as described in this example, magenta step wedges which have the maximum color densities and 7 values given in Table 3 are obtained. All the samples obtained in this way have much less dye graininess than those obtained using p-methylaminophenol-hydroquinone developer.

TABLE 3 Maximum color densities 7 Value Developer:

Example 3 30 parts of a 1% aqueous solution of 6-methyl-4-hydroxyl l,3,3a,7-tetraazaindene, 300 parts of a 2% aqueous solution of the yellow dye of the following formula:

SOaH

blue light, is applied to the support mentioned in Example 1 in such a manner that the layer contains 0.80 g. of silver per square metre after drying. Samples of the resulting material are exposed to white light behind a grey step wedge which has a logarithmic density increase of 0.10 and then treated in baths 1 to 8 according to the example. The sensitometric measurements showed a maximum color density of 0.98 and a 7 value of 0.5. The resulting yellow step wedge is practically grainless. If the layer is exposed in the same manner and then developed for 5 minutes or 1 minute, respectively, in the said p-methylaminophenol-hydroquinone developer and then treated as described in Example 1, maximum color densities of 0.94 and 0.96, respectively, and values of 1.8 and 1.6, respectively, and a coarser dye grain is obtained.

EXAMPLE 4 The following layers are applied successively to a support of prepared white pigmented cellulose acetate:

(1) The red sensitive emulsion given in Example 1 (silver application 0.95 g. of silver per m.

(2) A gelatin intermediate layer;

(3) The green sensitive layer given in Example 2 (silver application 0.88 g. of silver per m.

(4) A thin intermediate layer of gelatin;

(5 A yellow filter layer of colloidal silver;

(6) A thin intermediate layer of gelatin;

(7) The blue sensitive emulsion layer given in Example 3 (silver application 0.78 g. of silver per m?) and ('8) A thin protective layer of gelatin.

The molar ratio of silver to azo bonds in the individual layers is 20: 1, 29:1 and 20:1.

Samples of this material are exposed to White light behind a grey step wedge which has a logarithmic density increase of 0.10, and then processed as follows:

(a) in baths 1 to 8 for the same times as given in Example 1;

(b) 6, 5, 4 and 3 minutes development in p-methylaminophenolhydroquinone developer (1 a) of Example 1 and then treated in baths 2 to 8 as in (a); and

(c) 8 minutes development in developers I to V of EX- zzrggple 1 and then treated in baths 2 to 8 as in (a) and The following results are obtained:

Maximum Gradacolor than density Graininess (a) Bg 0.75 1.86 Very slight.

Pp 0. 1. 87 Do. Yellow 0. 2.15 Do.

(1)) 6 min. development Bg 2. 4 1.83 Strong. in l 2.3 1. 74 D0. Yellow 2. 5 2. 07 Do.

(13) 5 min. development Bg 2.3 1.83 D0. in 1b. Pp 2. 0 l. 81 Do. Yellow.. 2. 4 2. 15 Do.

(1)) 4 min. development Bg 2. 15 1.88 Do. 1n lb. Pp l. 90 1.76 Do. Yellow 2. 15 2. 10 D0.

(11) 3 min. development Bg 2.0 1.92 D0. in 1b. Pp 1. 1. 85 Do. Yellow. 2. 15 2. 17 Do.

(c) Developer I Bg 0.6 1. 91 Very slight.

Pp 0.6 1. 96 Do. Yellow 0. 7 2. 17 Do.

(0) Developer lI Bg 0.7 1.85 D0. P 0. 7 1. 94 Do. Yellow. 0. 85 2. 13 Do.

(0) Developer III Bg 0. 5 1.94 Do. Pp 0.5 2. 02 D0. Yellow 0. 55 2. 18 D0.

(0) Developer IV Bg 0.6 1.90 Do. Pp 0. 6 1.91 Do. Yellow 0.65 2.15 D0.

(0) DeveloperV Bg 1. 25 1. 70 Do. p 1. 25 1. 80 D0. Yellow 1. 35 2. 03 Do.

What is claimed is:

1. A process for the production of colored photographic images by the silver dye bleaching process by exposing a photographic material which has at least one silver halide emulsion layer which contains an azo dye, developing, bleaching the dye and bleach-fixing, chracterised in that a silver halide emulsion in which the molar ratio of silver per azo bond of the bleachable azo dye is at least 12:1 is used and that development is carried out with a developer of the p-phenylene diamine series which has a high sulfite content.

2. A process according to claim 1, characterised in that a silver halide emulsion which has a silver content (in the form of silver halide) of at least 10 g. per kg. and a molar ratio of silver to dye of 16:1 to 25:1 per azo bond is used.

3. A process according to claim 1, characterised in that development is carried out using a developer which contains, per litre, 0.5 to 25 g. of a developer substance of the p-phenylene diamine series Which has a sulfite content of 15 to 60 g. per litre.

References Cited UNITED STATES PATENTS 2,042,253 5/1936 Gaspar 96-53 FOREIGN PATENTS 416,666 9/1934 Great Britain 9653 517,628 2/ 1940 Great Britain 96-99 J. TRAVIS BROWN, Primary Examiner US. Cl. X.R. 9620 273? UNl'li'ID S'M'Hzs PA'IENI OFFICE 5 s V 1 1 w a v CERTWICA'L l; 01* CURRLL F [ON Dated J 15 1921 Patent No. 3 ,585 ,032

Inventor(s)flrj ch Bockly et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 60, "uese" should be use Column 2, line 13, the right hand part of that formula should read as follows:

Signed and sealed this 8th day of February 1972.

(SEAL) Attest:

EDWARD M.FLETCHEB,JR. Attesting Officer ROBERT GOTTSCHALK Commissioner of Patents