EP1006408B1 - Bleaching bath for photographic black and white material - Google Patents
Bleaching bath for photographic black and white material Download PDFInfo
- Publication number
- EP1006408B1 EP1006408B1 EP99123138A EP99123138A EP1006408B1 EP 1006408 B1 EP1006408 B1 EP 1006408B1 EP 99123138 A EP99123138 A EP 99123138A EP 99123138 A EP99123138 A EP 99123138A EP 1006408 B1 EP1006408 B1 EP 1006408B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- bleaching
- permanganate
- bleaching bath
- bath
- condensed phosphates
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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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
- G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
- G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
- G03C5/264—Supplying of photographic processing chemicals; Preparation or packaging thereof
- G03C5/266—Supplying of photographic processing chemicals; Preparation or packaging thereof of solutions or concentrates
-
- 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
- G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
- G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
- G03C5/40—Chemically transforming developed images
- G03C5/44—Bleaching; Bleach-fixing
-
- 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
- G03C2200/00—Details
- G03C2200/44—Details pH value
Definitions
- the invention relates to a bleaching bath for black and white photographic silver halide material.
- bleaching baths are used to bleach the developed silver, which contain a strongly acidic potassium dichromate solution with approximately 7.5 g K 2 Cr 2 O 7 / l as the oxidizing agent.
- the bleaching process produces a soluble silver salt, for example silver sulfate (Ag 2 SO 4 ), which is washed out of the photographic layer.
- Substances with a similarly high electrochemical oxidation potential as dichromate for example salts of tetravalent cerium, seven-valent manganese, of trivalent iron and persulfate solutions are unsuitable because they are metallic Oxidize silver slowly even at high concentrations (bleaching times of more than 10 minutes) or because, as in the case of the seven-valent manganese, it is sufficient active, but so unstable in solution that they decompose after a short time and on the tank walls, in the hoses, on all parts of the device and on the Films depicting Braunstein.
- oxidizing agents mentioned in combination with known bleaching accelerators e.g. Using thioglycerin is also unsuccessful because of the bleaching times still over 10 minutes. This procedure also requires an additional one Bad (Vorbad) because sulfur compounds such as thioglycerin from the oxidizing agents immediately oxidized in a shared bathroom and thus ineffective would.
- the object of the invention was therefore to provide a bleaching bath for black and white silver halide materials, that bleaching in a timely manner ( ⁇ 10 Minutes), is stable and can be used in regenerated continuous operation. Furthermore, the bleaching bath should be free of dichromate.
- the invention therefore relates to a bleaching bath for black-and-white silver halide photographic materials with a pH of 0.4 to 4 and permanganate ions as a bleaching agent, characterized in that it contains condensed phosphates.
- the bleaching bath has a pH from 1 to 2.
- the bleach bath contains 0.5 to 10 g / l permanganate and 1 to 100 g / l condensed phosphates. In one particularly preferred embodiment of the invention contains the bleaching bath 1 to 4 g / l permanganate and 5 to 30 g / l condensed phosphates.
- pH of such a bleaching bath is included Sulfuric acid or hydrogen sulfate is adjusted.
- Condensed phosphates are a group of - due to their production also called melting or glow phosphates - phosphates that differ from allow acidic salts of orthophosphoric acid to be removed by condensation.
- condensed Phosphates or polyphosphates contain more than one phosphorus atom per Molecule.
- medium to high molecular weight polyphosphates examples include Graham's salt, Maddrell's salt and Kurrol's salt.
- Concentrate A contains permanganate ions and condensed phosphates and is adjusted to a pH value of ⁇ 6.
- potassium permanganate is used as the bleaching agent used.
- a commercially available black and white film e.g. Agfapan APX-100 was made with a Grayscale wedge exposed, at 20 ° C for 8 minutes in a commercially available black and white developer (e.g. refinal) developed, fixed, watered and dried.
- a commercially available black and white developer e.g. refinal
- Grayscale wedges produced in this way were subsequently bleached with different materials Treated composition and determined the time required to complete the to completely bleach metallic silver of the grayscale wedge, i.e. until only that clear base of the film was visible (test series C).
- test series A The stability of the tank solutions was also examined (test series A). To the solutions were filled in PE bottles and over a period of 42 days stored at room temperature. Depending on the degree of stabilization of the permanganate more or less brown stone forms on the bottle walls. The strength of the Deposits thus serve as a measure of the stability of the tank solutions.
Description
Die Erfindung betrifft ein Bleichbad für schwarz-weiß-fotografisches Silberhalogenidmaterial.The invention relates to a bleaching bath for black and white photographic silver halide material.
Bei der Verarbeitung von Schwarz-Weiß-Umkehrmaterialien sowie in der Mikrografie und im grafischen Bereich werden zum Bleichen des entwickelten Silbers Bleichbäder verwendet, die als Oxidationsmittel eine stark saure Kaliumdichromatlösung mit etwa 7,5 g K2Cr2O7/l enthalten. Beim Bleichvorgang entsteht ein lösliches Silbersalz, z.B. Silbersulfat (Ag2SO4), das aus der fotografischen Schicht ausgewaschen wird.In the processing of black-and-white reversal materials, as well as in micrography and graphics, bleaching baths are used to bleach the developed silver, which contain a strongly acidic potassium dichromate solution with approximately 7.5 g K 2 Cr 2 O 7 / l as the oxidizing agent. The bleaching process produces a soluble silver salt, for example silver sulfate (Ag 2 SO 4 ), which is washed out of the photographic layer.
Aus ökologischen Gründen ist es notwendig geworden, die Dichromatmenge zu vermindern oder vorzugsweise dichromathaltige Bleichbäder ganz zu vermeiden.For ecological reasons it has become necessary to reduce the amount of dichromate or preferably avoid bleach baths containing dichromate altogether.
Substanzen mit ähnlich hohem elektrochemischen Oxidationspotential wie Dichromat, beispielsweise Salze des vierwertiges Cers, des siebenwertigen Mangans, des dreiwertigen Eisens sowie Persulfatlösungen sind ungeeignet, weil sie metallisches Silber selbst bei hoher Konzentration nur langsam oxidieren (Bleichzeiten von mehr als 10 Minuten) oder weil sie, wie im Falle des siebenwertigen Mangans, zwar ausreichend aktiv, in Lösung jedoch so instabil sind, daß sie sich nach kurzer Zeit zersetzen und an den Tankwänden, in den Schläuchen, an allen Geräteteilen und auf den Filmen Braunstein abscheiden.Substances with a similarly high electrochemical oxidation potential as dichromate, for example salts of tetravalent cerium, seven-valent manganese, of trivalent iron and persulfate solutions are unsuitable because they are metallic Oxidize silver slowly even at high concentrations (bleaching times of more than 10 minutes) or because, as in the case of the seven-valent manganese, it is sufficient active, but so unstable in solution that they decompose after a short time and on the tank walls, in the hoses, on all parts of the device and on the Films depicting Braunstein.
Die genannten Oxidationsmittel in Kombination mit bekannten Bleichbeschleunigern z.B. Thioglycerin einzusetzen, führt ebenfalls nicht zum Erfolg, da die Bleichzeiten weiterhin über 10 Minuten liegen. Außerdem erfordert diese Verfahrensweise ein zusätzliches Bad (Vorbad), weil Schwefelverbindungen wie Thioglycerin von den Oxidationsmitteln in einem gemeinsamen Bad sofort oxidiert und damit unwirksam würden. The oxidizing agents mentioned in combination with known bleaching accelerators e.g. Using thioglycerin is also unsuccessful because of the bleaching times still over 10 minutes. This procedure also requires an additional one Bad (Vorbad) because sulfur compounds such as thioglycerin from the oxidizing agents immediately oxidized in a shared bathroom and thus ineffective would.
Aufgabe der Erfindung war daher die Bereitstellung eines Bleichbades für Schwarz-Weiß-Silberhalogenidmaterialien, das eine Bleichung in angemessener Zeit (<10 Minuten) gestattet, stabil ist und im regenerierten Dauerbetrieb benutzt werden kann. Weiterhin soll das Bleichbad dichromatfrei sein.The object of the invention was therefore to provide a bleaching bath for black and white silver halide materials, that bleaching in a timely manner (<10 Minutes), is stable and can be used in regenerated continuous operation. Furthermore, the bleaching bath should be free of dichromate.
Wie bereits oben erwähnt, besitzen Permanganat-Ionen zwar eine gute Bleichwirkung, zersetzen sich in Lösung jedoch leicht unter der Bildung von Braunstein.As mentioned above, while permanganate ions have a good bleaching effect, however, decompose easily in solution to form brown stone.
Versuche, Permanganatlösungen mit Salzen von Metallen der 1. oder 2. Nebengruppe des Periodensystems zu stabilisieren zeigen zwar eine Wirkung; jedoch reicht die erzielte Stabilität der Lösung für den Einsatz in der Praxis nicht aus (US-A-5 716 767).Attempts to permanganate solutions with salts of metals of the 1st or 2nd subgroup stabilizing the periodic table has an effect; however, is enough the achieved stability of the solution for use in practice is not sufficient (US-A-5 716 767).
Die Stabilisierung von Permanganat-Ionen in Lösung durch handelsübliche Komplexbildner wie Polycarbonsäuren oder Phosphonsäuren in Analogie zu Eisenionen scheitert an der Instabilität der Komplexbildner in Gegenwart von Permanganat-Ionen.The stabilization of permanganate ions in solution using commercially available complexing agents such as polycarboxylic acids or phosphonic acids in analogy to iron ions fails due to the instability of the complexing agents in the presence of permanganate ions.
Neuere Untersuchungen haben nun gezeigt, daß bei der Verwendung von Permanganat-Ionen als Bleichmittel eine hohe Bleichgeschwindigkeit und eine geringe Braunsteinbildung in der Silberhalogenidemulsionsschicht nur bei einem niedrigen pH-Wert möglich ist. Bei niedrigem pH-Wert ist die Haltbarkeit der Bleichlösung unzureichend.Recent studies have now shown that when using permanganate ions as a bleaching agent, a high bleaching speed and a low formation of mist in the silver halide emulsion layer only at a low pH is possible. At low pH the shelf life of the bleaching solution is insufficient.
Es wurde weiterhin beobachtet, daß ein Bleichbad mit Permanganat-Ionen als Bleichmittel bei einem pH-Wert von 1,6 weniger stabil ist, wenn der pH-Wert mit Schwefelsäure eingestellt wird, als wenn er mit Phosphorsäure eingestellt wird. Offenbar stabilisieren die Phosphationen das Bleichbad. Bei höheren Konzentrationen wird jedoch die Bleichwirkung behindert, ohne daß die Haltbarkeit bereits ausreichend wäre. It was also observed that a bleach bath with permanganate ions as the bleach at a pH of 1.6 is less stable when the pH is with sulfuric acid is set as if it was set with phosphoric acid. apparently the phosphate ions stabilize the bleach bath. At higher concentrations however, the bleaching effect is hampered without the durability being sufficient would.
In dieser komplexen Situation wurde überraschenderweise gefunden, daß besonders kondensierte Phosphate eine stabilisierende Wirkung auf Permanganatlösungen haben und die Braunsteinbildung deutlich verzögern, ohne daß die Bleichwirkung beeinträchtigt wird.In this complex situation it was surprisingly found that particularly condensed phosphates have a stabilizing effect on permanganate solutions have and significantly delay the formation of manganese without impairing the bleaching effect becomes.
Gegenstand der Erfindung ist daher ein Bleichbad für fotografische Schwarz-Weiß-Silberhalogenidmaterialien mit einem pH-Wert von 0,4 bis 4 und Permanganat-Ionen als Bleichmittel, dadurch gekennzeichnet, daß es kondensierte Phosphate enthält.The invention therefore relates to a bleaching bath for black-and-white silver halide photographic materials with a pH of 0.4 to 4 and permanganate ions as a bleaching agent, characterized in that it contains condensed phosphates.
In einer bevorzugten Ausführungsform der Erfindung hat das Bleichbad einen pH-Wert von 1 bis 2.In a preferred embodiment of the invention, the bleaching bath has a pH from 1 to 2.
Es hat sich als besonders vorteilhaft erwiesen, wenn die Konzentration der kondensierten Phosphate im Bleichbad die 2- bis 10-fache Menge des Gewichtes der eingesetzten Permanganatmenge beträgt.It has proven to be particularly advantageous if the concentration of the condensed Phosphates in the bleaching bath 2 to 10 times the weight of the used Amount of permanganate.
Daher enthält das Bleichbad in einer bevorzugten Ausführungsform der Erfindung 0,5 bis 10 g/l Permanganat und 1 bis 100 g/l kondensierte Phosphate. In einer besonders bevorzugten Ausführungsform der Erfindung enthält das Bleichbad 1 bis 4 g/l Permanganat und 5 bis 30 g/l kondensierte Phosphate.Therefore, in a preferred embodiment of the invention, the bleach bath contains 0.5 to 10 g / l permanganate and 1 to 100 g / l condensed phosphates. In one particularly preferred embodiment of the invention contains the bleaching bath 1 to 4 g / l permanganate and 5 to 30 g / l condensed phosphates.
Weiterhin ist es bevorzugt, wenn der pH-Wert eines solchen Bleichbades mit Schwefelsäure oder Hydrogensulfat eingestellt wird.Furthermore, it is preferred if the pH of such a bleaching bath is included Sulfuric acid or hydrogen sulfate is adjusted.
Unter kondensierten Phosphaten versteht man eine Gruppe von - aufgrund ihrer Herstellung auch Schmelz- oder Glühphosphate genannten - Phosphaten, die sich von sauren Salzen der Orthophosphorsäure durch Kondensation ableiten lassen. Kondensierte Phosphate oder Polyphosphate enthalten mehr als ein Phosphoratom pro Molekül. Condensed phosphates are a group of - due to their production also called melting or glow phosphates - phosphates that differ from allow acidic salts of orthophosphoric acid to be removed by condensation. condensed Phosphates or polyphosphates contain more than one phosphorus atom per Molecule.
Die kondensierten Phosphate lassen sich in die ringförmigen Metaphosphate Ml n(PO3)n und die kettenförmigen Polyphosphate Ml n+2PnO3n+l bzw. Ml nH2PnO3n+l einteilen (Ml = einwertiges Metall oder Ammonium, n = 3, 4, 5 usw.). Sie bestehen aus PO4-Tetraedern, die über gemeinsame Sauerstoffatome verknüpft sind.The condensed phosphates can be divided into the ring-shaped metaphosphates M l n (PO 3 ) n and the chain polyphosphates M l n + 2 P n O 3n + l and M l n H 2 P n O 3n + l (M l = monovalent metal or ammonium, n = 3, 4, 5, etc.). They consist of PO 4 tetrahedra that are linked via common oxygen atoms.
Die Herstellung der kondensierten Phosphate ist bekannt und z.B. in Ullmanns Encyklopädie der technischen Chemie, 4. Auflage (1979), Band 18, Seite 328 beschrieben. Von besonderer technischer Bedeutung ist die thermische Dehydratisierung von Natriumdihydrogenphosphat. Man erhält in Abhängigkeit von den Reaktionsbedingungen verschiedene Polyphosphate.The preparation of the condensed phosphates is known and e.g. in Ullmanns Encyklopedia of technical chemistry, 4th edition (1979), Volume 18, page 328. Thermal dehydration is of particular technical importance of sodium dihydrogen phosphate. One obtains depending on the reaction conditions various polyphosphates.
Beispiele für mittel- bis hochmolekulare Polyphosphate sind das Grahamsche Salz, das Maddrellsche Salz und das Kurrolsche Salz.Examples of medium to high molecular weight polyphosphates are Graham's salt, Maddrell's salt and Kurrol's salt.
Als besonders vorteilhaft für den Einsatz in dem erfindungsgemäßen Bleichbad hat sich ein Gemisch aus hochmolekularen, kettenförmigen Polyphosphaten mit einem geringen Anteil (ca. 5 bis 10 Gew.-%) an Metaphosphat erwiesen. Solche Gemische sind auch als Calgon® (Marke der Firma Benckiser GmbH) oder in den USA unter der Bezeichnung Hexametaphosphat bekannt.Has been particularly advantageous for use in the bleaching bath according to the invention a mixture of high molecular, chain-shaped polyphosphates with a low proportion (about 5 to 10 wt .-%) of metaphosphate proven. Such mixtures are also available as Calgon® (brand of Benckiser GmbH) or in the USA under the Designation known as hexametaphosphate.
In der Praxis hat es sich bewährt, das Bleichbad bzw. den Regenerator aus wenigstens zwei Konzentraten anzusetzen. Konzentrat A enthält Permanganat-Ionen und kondensierte Phosphate und ist auf einen pH-Wert ≥6 eingestellt. Konzentrat B enthält Schwefelsäure oder Hydrogensulfat in einer Menge, um den pH-Wert des Bleichbades auf 0,4 bis 4, vorzugsweise 1 bis 2, einzustellen.In practice, it has proven useful to use the bleach bath or the regenerator at least to prepare two concentrates. Concentrate A contains permanganate ions and condensed phosphates and is adjusted to a pH value of ≥6. Contains concentrate B. Sulfuric acid or hydrogen sulfate in an amount to adjust the pH of the Set the bleaching bath to 0.4 to 4, preferably 1 to 2.
Als Bleichmittel wird in einer bevorzugten Ausführungsform der Erfindung Kaliumpermanganat verwendet. In a preferred embodiment of the invention, potassium permanganate is used as the bleaching agent used.
Ein Beispiel für ein besonders bevorzugtes Bleichbad ist nachfolgend angegeben:
Ein handelsüblicher Schwarz-Weiß-Film, z.B. Agfapan APX-100 wurde mit einem Graustufenkeil belichtet, bei 20°C 8 Minuten in einem handelsüblichen Schwarz-Weiß-Entwickler (z.B. Refinal) entwickelt, fixiert, gewässert und getrocknet.A commercially available black and white film, e.g. Agfapan APX-100 was made with a Grayscale wedge exposed, at 20 ° C for 8 minutes in a commercially available black and white developer (e.g. refinal) developed, fixed, watered and dried.
So hergestellte Graustufenkeile wurden anschließend mit Bleichbädern verschiedener Zusammensetzung behandelt und die Zeit bestimmt, die erforderlich ist, um das metallische Silber des Graustufenkeils komplett zu bleichen, d.h. bis nur noch die klare Unterlage des Films sichtbar war (Versuchsreihe C).Grayscale wedges produced in this way were subsequently bleached with different materials Treated composition and determined the time required to complete the to completely bleach metallic silver of the grayscale wedge, i.e. until only that clear base of the film was visible (test series C).
Bei dem Bleichprozess wurden die Parameter wie Temperatur und Agitation konstant gehalten. Der pH-Wert wurde jeweils eingestellt und die nachfolgend angegebenen Konzentrationen an Wirkstoffen vorgegeben.During the bleaching process, parameters such as temperature and agitation became constant held. The pH was adjusted in each case and those given below Concentrations of active ingredients specified.
Weiterhin wurde die Stabilität der Tanklösungen untersucht (Versuchsreihe A). Dazu wurden die Lösungen in PE-Flaschen gefüllt und über einen Zeitraum von 42 Tagen bei Raumtemperatur gelagert. Je nach Grad der Stabilisierung des Permanganats bildet sich mehr oder weniger Braunstein an den Flaschenwänden. Die Stärke der Ablagerungen dient somit als Maß für die Stabilität der Tanklösungen.The stability of the tank solutions was also examined (test series A). To the solutions were filled in PE bottles and over a period of 42 days stored at room temperature. Depending on the degree of stabilization of the permanganate more or less brown stone forms on the bottle walls. The strength of the Deposits thus serve as a measure of the stability of the tank solutions.
Zusätzlich wurde auch noch die Braunsteinbildung während des Bleichvorgangs überprüft (Versuchsreihe B). Gleichzeitig zur Oxidation des Bildsilbers bildet sich Braunstein in der Filmschicht. Die Stärke der Braunsteinbildung ist ebenfalls vom Grad der Stabilisierung des Permanganats abhängig.In addition, there was also the formation of manganese during the bleaching process checked (test series B). Forms simultaneously with the oxidation of the image silver Brown stone in the film layer. The strength of the brownstone formation is also from Degree of stabilization of the permanganate depending.
Bei allen Versuchen wurde im Bleichbad eine Kaliumpermanganat-Konzentration
von 2 g/l eingestellt.
mit pH= 1,6 (H2SO4)
mit c(KH2PO4)= 20 g/l
mit pH= 1,6 (H2SO4)
- keine
▪ minimal
▪ ▪ leicht
▪ ▪ ▪ deutlich
▪ ▪ ▪ ▪ stark
▪ ▪ ▪ ▪ ▪ sehr stark
with pH = 1.6 (H 2 SO 4 )
with c (KH 2 PO 4 ) = 20 g / l
with pH = 1.6 (H 2 SO 4 )
- no
▪ minimal
▪ ▪ easy
▪ ▪ ▪ clearly
▪ ▪ ▪ ▪ strong
Very strong
Claims (4)
- Bleaching bath for photographic black-&-white silver halide materials having a pH of from 0.4 to 4 and containing permanganate ions as bleaching agent, characterized in that it contains condensed phosphates.
- Bleaching bath according to Claim 1, characterized in that it contains from 1 to 4 g/l of permanganate and from 5 to 30 g/l of condensed phosphates.
- Bleaching bath according to Claim 1, characterized in that it contains potassium permanganate as bleaching agent.
- Bleaching bath according to Claim 1, characterized in that it contains a mixture of high-molecular-weight, chain-form polyphosphates having a low content (from about 5 to 10% by weight) of metaphosphate as condensed phosphates.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19855330 | 1998-12-01 | ||
| DE19855330A DE19855330C1 (en) | 1998-12-01 | 1998-12-01 | Permanganate bleach bath for photographic black-and-white silver halide material, e.g. reversal and (micro)graphic material, contains condensed phosphates |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP1006408A1 EP1006408A1 (en) | 2000-06-07 |
| EP1006408B1 true EP1006408B1 (en) | 2002-02-13 |
Family
ID=7889580
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP99123138A Expired - Lifetime EP1006408B1 (en) | 1998-12-01 | 1999-11-19 | Bleaching bath for photographic black and white material |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP1006408B1 (en) |
| DE (2) | DE19855330C1 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19549103A1 (en) * | 1995-12-29 | 1997-07-03 | Agfa Gevaert Ag | Bleach bath for black and white photographic material |
-
1998
- 1998-12-01 DE DE19855330A patent/DE19855330C1/en not_active Expired - Fee Related
-
1999
- 1999-11-19 DE DE59900859T patent/DE59900859D1/en not_active Expired - Fee Related
- 1999-11-19 EP EP99123138A patent/EP1006408B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE59900859D1 (en) | 2002-03-21 |
| EP1006408A1 (en) | 2000-06-07 |
| DE19855330C1 (en) | 2000-04-13 |
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