Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C7/00—Multicolour photographic processes or agents therefor; Regeneration of such processing agents; Photosensitive materials for multicolour processes
  • G03C7/28—Silver dye bleach processes; Materials therefor; Preparing or processing such materials

Definitions

• This invention relates to a photographic material and to a process for the production of colored photographic images by the silver dye bleaching 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..
• 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.
• 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.
• 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.
• 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.
• amounts of about 15 to 60 g. of sulfite are used per 1 litre of solution; it is preferred to use 20 to g.
• 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.
• a silver dye bleaching material according to the invention is prepared and processed as follows:
• 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.
• Formalin aqueous solution 70 ml. Sodium bicarbonate-5 g. Water up to 1,000 ml.
• 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.
• 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.
• 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.
• 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:
• 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.
• 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.
• 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:
• Example 2 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.
• EXAMPLE 4 The following layers are applied successively to a support of prepared white pigmented cellulose acetate:
• 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 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.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=5701125

Family Applications (1)

Country Status (6)

• 1968
  • 1968-04-04 DE DE19681772137 patent/DE1772137A1/de active Pending
• 1969
  • 1969-03-21 US US809407A patent/US3585032A/en not_active Expired - Lifetime
  • 1969-03-21 CH CH432869A patent/CH528100A/de not_active IP Right Cessation
  • 1969-03-27 GB GB06077/69A patent/GB1253892A/en not_active Expired
  • 1969-03-28 BE BE730611D patent/BE730611A/xx unknown
  • 1969-04-04 FR FR6910438A patent/FR2005559A1/fr not_active Withdrawn

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