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

• the so-called silver-dyestuff bleaching process has been known for a long time.
• the individual component color images are first produced as silver images in layers that are either previously homogeneously colored with dyestulf or are homogeneously colored after production of the silver image.
• the dyestuif is then bleached in a dyestuii bleaching operation locally in accordance with characteristics of the image depending on the distribution of silver in the component image, the dyestutl' being destroyed at those parts of the image where silver is present.
• the bleaching operation is carried out in a plurality of different colored layers or media.
• the present invention provides a method for producing by the silver-dye bleaching process photographic pictures composed of at least two component color images, wherein at least two dyestuff bleaching baths are used in succession for bleaching the several component color images and at least one of the dyestulf bleaching baths has a substantially selective action.
• the second dyestutf bleaching bath bleaches out substantially only the dyestuff of the residual component image not bleached by the first bath.
• this varying action is achieved by' incorporating in at least one bath serving for bleaching-out one or more dyestutis a substance which has an accelerating action on the bleaching of the dyestuffs associated with one or other of the component-color images and/or simultaneously a retarding and/or inhibiting action on the bleaching of at least one dyestuff in another component color image.
• substances some of which can be regarded as selective bleaching catalysts, are, for example, riboflavine, lumazine and alloxazine.
• thiourea can also be used in the method of this invention as a selective accelerating or retarding substance.
• mild oxidizing agents, tartrazine, nitrobenzene sulfonic acid etc. such as are described, for example, in British specifications Nos. 539,190, 539,391 and 539,509, as additions to bleaching baths, act in the same manner.
• a further advantage of themethod of this invention in which the bleaching is divided between two successive baths is that one or more other baths of any kind may be interposed between the two color bleaching baths, which additional baths may serve to act upon one or some of the component images.
• additional baths may serve to act upon one or some of the component images.
• a silver reducing bath there may be interposed between the first and second dyestuff bleaching baths a silver reducing bath, whereby the gradation of the dyestutf image formed in the succeeding second dyestuif bleaching bath can be selectively influenced.
• the gradation of the dyestutf image formed in the succeeding second dyestuif bleaching bath can be selectively influenced.
• An important feature of the invention therefore lies in 'the use of a plurality of successive dyestutf bleaching baths, each of which baths produces only a part of a color image.
• the advantages of the method of this invention as compared with the known methods are obvious.
• the dyestuffs generally used are not bleached in an identical manner in the bleaching bath.
• a more easily bleachable dyestulf is bleached out too strongly so that it yields an image of too steep gradation.
• a method involving a single bleaching bath fails when a photographic material having more than one layer is used, for example, the usual 3-color layer materials used at the present time, because it is not possible selectively to control the bleaching process in the individual layers, for example, by simple variation in the period of action of the bleaching bath.
• the possibility afforded by the method of this invention of controlling the bleaching process in the several layers is thus of fundamental importance for achieving color balance and therefore an image of good quality.
• the multi-color material may be bleached in any of the successive bleaching baths for a period long enough to bleach completely at least one of the dyestuffs so that silver and dyestuff do not exist simultaneously at any part of the image.
• the treatment in the individual bleaching baths may be interrupted at an earlier stage when none or only a few of the dyestuffs capable of being bleached by a given bleaching bath have been completely bleached, or the bleaching may be interrupted prematurely for some of the dyestuffs and completed for the other dyestuffs, the baths being used in any desired order of succession.
• the invention also includes the use in the dyestufi bleaching baths of substances which partially retard or partially accelerate the bleaching-out of different dyestuffs. If desired, such selective bleaching of the several color layers may also be brought about by adjusting certain conditions in the baths, for example, temperature, pH- value, etc.
• the successive bleaching baths may be alkaline or acid, or one of the baths may be alkaline and another may be acid.
• the photographic material may be original or copy material, pictures to be viewed by refracted or transmitted light, cinematograph film or material for instantaneous photography.
• the photographic material may be composed of separate layers or mixed granular emulsions.
• EXAMPLE 1 A three-layer film was used having a red-sensitized layer, which was dyed with a dyestuff described in Schultz, Farbstotftabellen, 7th Edition, Vol. II, pages 220- 222-E.I. 142 (C1. Direct Green 27), then a green-sensitized layer, which was dyed with a dyestuff described in Schultz, Farbstotftabellen, 7th Edition, Vol. 11, page 48-E.I. 79, (Cl.
• the bleached baths mentioned below were used for bleaching, and then the excess of silver was oxidized in a ferricyanide bath and eliminated in a fixing bath. Hardening was carried out in a formaldehyde bath before bleaching, and the material was thoroughly washed with water after treatment in each of the baths.
• Bleaching Baths 100 grams of potassium bromide and 100 cc. of pure concentrated hydrochloric acid, made up to l-liter with water 100 grams of potassium bromide and 100 cc. of pure concentrated hydrochloric acid, 0.05 gram of riboflavine made up to 1 liter with water 100 grams of potassium bromide 100 cc. of pure concentrated hydrochloric acid, alloxazine saturated (less than 0.05 gram) made up to 1 liter with water 50 grams of thiourea 100 cc. of pure concentrated hydrochloric acid made up to 1 liter with water 100 grams of potassium bromide and 100 cc.
• ribofiavine and amidol has an accelerating action towards the blue-green image and a very slight retarding action towards the yellow image as compared with the bath A that was free from additions.
• thiourea and hydroquinone have an accelerating action towards the yellow and purple images.
• EXAMPLE 3 The starting material used in Example 1 was treated first for 15 minutes in bath D, and then for 3 minutes in bath C, whereby a satisfactory harmony between the color gradations in the three layers was obtained.
• Example 4 The starting material used in Example 1 was bleached in bath E for 20 minutes, then treated in farmers reducer for 5 minutes, and was finally bleached for 15 minutes in bath F. A very good balance of the three-color gradations was obtained.
• EXAMPLE 5 The starting material described in Example 1 was exposed, developed and fixed in the manner described in that example. The material so treated was then treated first for 5 minutes in the bleaching bath H described below and then for 50 minutes in the bleaching bath I described below.
• EXAMPLE 6 The starting material used in Example 1 was bleached first for 30 minutes in bath I. In this bath the yellow and purple images were formed and at the same time a relatively large part of the silver image was removed, so that after a little practice the color balance of the image could be visually assessed (or if desired determined by densitometric measurement). Thus, the subsequent bleaching in bath H could be carried out, after repeated inspection, until the cyan image had been bleached to the desired extent. The image was then finished by removing the silver still present.
• the bleaching bath used for bleaching out the dyestutf of at least one, but less than all of the component images contains a substance that accelerates the bleaching out of the dyestuif of one component image and simultaneously retards the bleaching of the dyestuff of at least one other component image, which substance is a member selected from the group consisting of ribofiavine, lumazine, alloxazine, amidol, hydroquinone, thiourea and 2:3-aminooxyphenazine.
• a method according to claim 2 wherein there is interposed between two successive bleaching operations at least one silver-reducing operation that affects only a silver image as yet unbleached.
• the bleaching bath used for bleaching out the dyestuff of at least one, but less than all of the component images contains a substance that accelerates the bleaching out of the dyestuff of one component image and simultaneously inhibits the bleaching of the dyestuif of at least one other component image, which substance is a member selected from the group consisting of ribofiavine, lumazine, alloxazine, amidol, hydroquinone, thiourea and 2:3-amino-oxyphenazine.
• dyestulf which improvement consists essentially of subjecting the dyestuff contained in different component images of the photographic material, after full formation of the silver images, to bleaching out treatment comprising two successive bleaching operations in different dyestuff bleaching baths, one bleaching bath containing amidol and the other bleaching bath containing hydroquinone, each of said baths exerting a different bleaching action on at least one and the same component image, thereby acceleratedly bleaching out dyestuff of at least one, but less than all, of the component images in at least one of said bleaching operations, and bleaching out dyestutf of from at least the remaining up to all of the component images in the other bleaching operation; and so adjusting the accelerated bleaching to the other bleaching as to yield a predetermined balance between the gradations of the color component images in the different layers.

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

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Citations (6)

• 0
  • BE BE579274D patent/BE579274A/xx unknown
• 1958
  • 1958-06-03 CH CH6017858A patent/CH370966A/de unknown
• 1959
  • 1959-05-15 FR FR794801A patent/FR1224564A/fr not_active Expired
  • 1959-05-26 GB GB17938/59A patent/GB879596A/en not_active Expired
  • 1959-06-01 US US817068A patent/US3156561A/en not_active Expired - Lifetime
  • 1959-06-02 DE DEC19112A patent/DE1091429B/de active Pending

Patent Citations (6)

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