US2518710A - Lumazines and alloxazines as catalysts in dye bleach baths for color photography - Google Patents
Lumazines and alloxazines as catalysts in dye bleach baths for color photography Download PDFInfo
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- US2518710A US2518710A US17574A US1757448A US2518710A US 2518710 A US2518710 A US 2518710A US 17574 A US17574 A US 17574A US 1757448 A US1757448 A US 1757448A US 2518710 A US2518710 A US 2518710A
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- Prior art keywords
- alloxazines
- lumazines
- silver
- dye
- catalysts
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- 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 method of processing photographic color pictures, and particularly to lumazines and alloxazines as accelerators for dye bleach baths used in producing dyestufi images from dyed silver images.
- the bleach baths employed in thisprocess, consist of an aqueous solution of a mineral acid or a mineral acid containing an alkali halide, such as potassium iodide, ammonium chloride, or both.
- an alkali halide such as potassium iodide, ammonium chloride, or both.
- Such baths require-a relatively long treating time so as to destroy the dyestnfi present in situ with the silver image.
- Long treatment in bleaching solutions of high acidity has the tendency to soften the gelatin of. the photographic emulsion containing a silver image and bleachable azo dye.
- a mineral acid or containing an alkali halide such as potassium iodide, ammonium chloride, or both.
- Such baths require-a relatively long treating time so as to destroy the dyestnfi present in situ with the silver image.
- Long treatment in bleaching solutions of high acidity has the tendency to soften the gelatin of. the photographic emulsion containing a silver
- the most practical catalysts so far suggested are the azines, such as phenazine, 2,3-diaminophenazine, and the like; Although -phenazine and its substituted products are effective as accelerators, they are highly colored substances and are substantive to gelatin, i. leave a stain in the gelatin layer which is diflicult to remove, and, which seriously aflects the quality of the final image.
- R and R1 which may be alike or difierent, represent a hydrogen atom, an alkyl or aryl group, e. g., methyl, ethyl, propyl, etc., phenyl, naphthy-l, and. the like
- Hg and R3 represent hydrogen or a methyl group
- R'zalways being hydrogen when R3 is methyl and R3 always being hydrogen when R2 is methyl
- Z represents the atoms necessary to complete an aromatic or heterocyclic ring, or ring system, e. g., benzene, naphthalene, anthracene, phenanthrene, pyridine, pyrimidine, and the like.
- aromatic and heterocyolic rings may be substituted in the various positions by one or more a kyl groups of the same value as R and R1, amino, phenyl, sulfanilamido, or .fused on a tetrahydrobenzene radical.
- rlumazines and alloxazine's are generally prepared by the condensation of an o-phenylenediamine or its homologues and alloxan.
- Lumarine lsipre ared accordin 'to the method iie'scr-ibed 1m J. :Amer. Chem. so'c. 67, 802, K1945) 'byihea'ting :glyoxalbisulfite and iifi-dianiino-ZG- iiihydroxypyriniidine together for 5 minutes ate temperature of 330'
- the methyl or phenyl substituted lumazi-ne's can be obtained firom ketoaldehydes, such as methylglyoxal or phenylglyoxal.
- the di-substitiltedderivatives can be obtained from dike'tones, sochdiacetyl or benzil.
- the lumaizine's and alloxazines may "be employed "in any mineral acid bleach bath, such as, tor example, “hydrochloric, hydrobromi'c, hyilrioiiic or phosphoric acid, with or without the presence of "an alkali halide, such as sodium or potassium bromide or iodide, sodium chloride, ammonium chloridayand-theilke.
- concentration of the acid .to be employed is dependent upon "the character of the gelatin constituting the photographic color emulsion layer or layers. Usually, the concentration of .the acid ranges 11p to 2 N. I prefer, howeverfto employ a'conce'ntration not higher than normal.
- the .amount'employed catalyst is not critical.
- .Anamount as small as 0.005 gram per liter ofbleach bath shows an appreciable bleaching action in silver bearing images. 'For practical purposes, amounts ranging from "0.005 to 2.6 grams -per liter-of bleach bath may be employed.
- any one-of the lumazines andallox'az'ines disclosed and contemplated herein may be employed in any mineral acid bleach hath, I .-prefer, however, to employ the alloxazines shown in illustrations 1-, -2, 4, 5, -8 to 14. and 18 to 24 'b'eof their general availability and ease 'df preparation.
- the ffollowin'g examples will illustrate the ⁇ preparationof a multi-layer color film, in which after exposure, the dye images are obtained by the silver dye bleach process, and .the bleach Uaths contaming the a'lloxazi'n'es as accelerators,
- EXAMPLE 1 kilograms of a wet ge atin'o sllverhalide emulsion, containing about 10% gelatin, 475% of silver-bromoiodide, zl0 cc. ofa 10% solution of sap'oniil, and '10 grams of diphenyl biguanide hydrochloride, were separated'irito three equal portions of .1 kilograms each and utilized in the preparation of the final red, green, and blue sensitive emuls ons.
- Red sensitive To the first portion of a red sensitized wet gelatinosil-ver-halide emulsion there were added 5 grams of a rbleachable cyan dye, Direct Sky Blue -.(C.-I. #520) Green sensitive *I'o the'second portion of a green sensitized wet gelatino silver-halide emulsion there were added 1.25 grams of a bleachable magenta dye," Fast Acid Magenta B (C. I. #30).
- Example II (a) Hydrochloric acid, conc cc 100 Potassium bromide grams 100 Water to make liter 1 '8 EXAMPLE II The bleaching treatment of Example I was repeated on the same fixed color"*film strips, with the exception that lumazine was substituted for alloxazine with similar results.
- EXAMPLE III A halogen silver-bearing layer colored with diamine pure blue FF (Schultz Farbslofitabellen 1931, 7th ed. #308) was treated with a bleach solution of the following composition:
- a dye bleach bath for producing a colored image in a photographic emulsion layer containing a bleachable azo dye and a silver image consisting of an aqueous solution of hydrochloric acid, ammonium chloride, potassium iodide and an accelerating amount of an agent selected from the group consisting of lumazines and alloxazines corresponding to the following general formulae:
- R and R1 represent a member selected from the class consisting of hydrogen, alkyl and aryl groups
- R2 and R3 represent a member selected from the class consisting of hydrogen and methyl group, R2 always being hydrogen when R: is methyland R3 always being hydrogen when R2 is methyl
- Z represents the atoms necessary'to complete a member selected from the class consisting of aromatic and heterocyclic ring systems's- 2.
- R C O l R1 /NH N C and wherein R and R1 represent a member selected from the class consisting of hydrogen, alkyl and 10 aryl groups, R2 and R3 represent a member selected from the class consisting of hydrogen and methyl group, R2 always being hydrogen when R3 is methyl and R3 always being hydrogen when R2 is methyl, and Z represents the atoms necessary to complete a member selected from the class consisting of aromatic and heterocyclic ring systems.
Description
Patented Aug. 15, 1950 .LUMAZIN ES AND ALLOXAZINES AS CATA- LYSTS IN DYE BLEACH RATES FOR COLOR PHOTOGRAPHY Fritz W. H. Mueller, Binghamton, N. Y., assignor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing.
This invention relates to a method of processing photographic color pictures, and particularly to lumazines and alloxazines as accelerators for dye bleach baths used in producing dyestufi images from dyed silver images.
It is known that in the production of photographic dyestufi images from diffusely dyed photographic emulsions containing a silver image, the latter image must be treated with a bleach bath which decolorizes or 'bleaches the dyestuff present in the photographic layer in the areas where the metallic silver is, present. The dyes, which are employed in the diff-use dyeing of the silver-halide emulsion layer, are-primarily azo dyes of the substantive and acidtype, although some basic vat dyes and alizarines may also be employed. The bleaching or decolorizatlon of the dyestuff is accomplished in a bleach bath in which there occurs a simultaneous.decoloriza-tion of the dye with an oxidation of the metal image at the points where silver is present, i. e.,-,the metallic silver is converted into a silver compound which may be removed subsequently by fixation in a solution of hypo.
The bleach baths, employed in thisprocess, consist of an aqueous solution of a mineral acid or a mineral acid containing an alkali halide, such as potassium iodide, ammonium chloride, or both. Such baths require-a relatively long treating time so as to destroy the dyestnfi present in situ with the silver image. Long treatment in bleaching solutions of high acidity has the tendency to soften the gelatin of. the photographic emulsion containing a silver image and bleachable azo dye. Moreover, by the use of such baths,
a lack of definition of the picture usually follows with other undesirable characteristics. In order to avoid these shortcomings, various organic compounds have been proposed as catalysts which, when added to the bleach bath, accelerate the action of said bath and materially reduce the bleaching time.
The most practical catalysts so far suggested are the azines, such as phenazine, 2,3-diaminophenazine, and the like; Although -phenazine and its substituted products are effective as accelerators, they are highly colored substances and are substantive to gelatin, i. leave a stain in the gelatin layer which is diflicult to remove, and, which seriously aflects the quality of the final image. I
I have discovered that lumazines and alloxazines, although colored substances ranging from orange to yellowish-green incolor, are not substantive to gelatin, do .not stain the gelatin layer,
Application March 27, 1948, Serial No. 17,574
8 Claims. (CI. 9588) and do not affect the duality of the final image. The lumazines and alloxazin'es presumably act as very fiective hydrogen carriers becoming readily reduced by the action of the bleach solution with concomitant oxidation of the silver image and destruction of the dye-in situ therewith.
The lumazines and alloxazines are characterized by the following general formulae:
wherein R and R1, which may be alike or difierent, represent a hydrogen atom, an alkyl or aryl group, e. g., methyl, ethyl, propyl, etc., phenyl, naphthy-l, and. the like, Hg and R3 represent hydrogen or a methyl group, R'zalways being hydrogen when R3 is methyl and R3 always being hydrogen when R2 is methyl, and Z represents the atoms necessary to complete an aromatic or heterocyclic ring, or ring system, e. g., benzene, naphthalene, anthracene, phenanthrene, pyridine, pyrimidine, and the like. The aromatic and heterocyolic rings may be substituted in the various positions by one or more a kyl groups of the same value as R and R1, amino, phenyl, sulfanilamido, or .fused on a tetrahydrobenzene radical.
The following are examples of the alloxazlnes employed in accordance with the present invention:
Alloxazine 24,2364 (1391) .27, 2116 (1894) N NH g 7 (or 8)-methy1a1loxazine B61. 32, 1653 (1399) Phenantrolumazine Ber. 70, 761 (1937) (4) N NH Lumazine Ber. 70, 761 (1937) (5) N NH E HIC- I 6 (or 7)-methyllumazine Ber. 70, 761 (1937) NE Hie C=O l H C y\ C ll 0 6.7-d1methyllumazine Ber. 70, 761 (1937) 7 (or 8)-ethy1alloxazlne Helv. Chim. Acta. 17,1516 (1934) 11 I CH NH N C l1 7.8dimethy1alloxazine Ber. 67, 1826 (1934) CH: N NE CH1 E1: (1H: NH
CH: N ("I o 7,8-tetramethy1enex 11loxazine Ber. '10, 1302 (1937) 7,8.9-trlmethyla1loxazine Helv. Chim. Acta. 18, 1134 (1935) 6,7-dimethyla1loxazlne Ber. 673, 1442-52 (1934) H NH m V Ed) N C H. g
6,8-dimethy1alloxazine Ber. 67B, 1442-52 (1934) N NH H NH 1N 0 7 -aminoalloxazine Journ. Indian Chem. Soc. 15, 77 (1938) 6 (or 7) -phenyllumazine Journ. Indian Chem. Soc. 14, 627 (1937) 6,7 (or 8,9)-benzoa11oxa.zine
Ber. 24, 2366 (1891) N N NH Aza-alloxazine Ber. 71B, 1243 (1938) rmemymnemime leerzes'oac near) (19) SCH:
no on.
nismmemyrsrrmm 3121224, 3031) (1159B 3.7-dlmeth'ylalloxa2in'e Ber. 24, 3030 (1891) .0 3,8-dlmeth'yldlloxazlne Ber. 24, 3030 (189.1)
C CH:
a Kar sr-methyrmranmmuuavifi 7 401- ee-euhamlemmeanmime Proc. seienc. 886 6194 19 HZ-he foregoing rlumazines and alloxazine's are generally prepared by the condensation of an o-phenylenediamine or its homologues and alloxan.
Lumarine lsipre ared accordin 'to the method iie'scr-ibed 1m J. :Amer. Chem. so'c. 67, 802, K1945) 'byihea'ting :glyoxalbisulfite and iifi-dianiino-ZG- iiihydroxypyriniidine together for 5 minutes ate temperature of 330' The methyl or phenyl substituted lumazi-ne's can be obtained firom ketoaldehydes, such as methylglyoxal or phenylglyoxal. The di-substitiltedderivativescan be obtained from dike'tones, sochdiacetyl or benzil.
fill-"of the foregding lu'mazines and alioxazines can be reduced to "form leuco derivatives which can here-oxidized with considerable ease,'a factor which greatly adds to their value as accelerators in accordance with the present invention.
"The lumaizine's and alloxazines may "be employed "in any mineral acid bleach bath, such as, tor example, "hydrochloric, hydrobromi'c, hyilrioiiic or phosphoric acid, with or without the presence of "an alkali halide, such as sodium or potassium bromide or iodide, sodium chloride, ammonium chloridayand-theilke. The concentration of the acid .to be employed is dependent upon "the character of the gelatin constituting the photographic color emulsion layer or layers. Usually, the concentration of .the acid ranges 11p to 2 N. I prefer, howeverfto employ a'conce'ntration not higher than normal.
inasmuch fee the lumazines and alloxazines are water-solubleyellow to brangeficompounds, which do not stain thegelatin, the .amount'employed catalyst is not critical. The :higher -the amount within practical limits the greater the catalytic activity. .Anamount as small as 0.005 gram per liter ofbleach bath shows an appreciable bleaching action in silver bearing images. 'For practical purposes, amounts ranging from "0.005 to 2.6 grams -per liter-of bleach bath may be employed. while any one-of the lumazines andallox'az'ines disclosed and contemplated herein may be employed in any mineral acid bleach hath, I .-prefer, however, to employ the alloxazines shown in illustrations 1-, -2, 4, 5, -8 to 14. and 18 to 24 'b'eof their general availability and ease 'df preparation.
The ffollowin'g examples will illustrate the \preparationof a multi-layer color film, in which after exposure, the dye images are obtained by the silver dye bleach process, and .the bleach Uaths contaming the a'lloxazi'n'es as accelerators,
EXAMPLE 1 kilograms of a wet ge atin'o sllverhalide emulsion, containing about 10% gelatin, 475% of silver-bromoiodide, zl0 cc. ofa 10% solution of sap'oniil, and '10 grams of diphenyl biguanide hydrochloride, were separated'irito three equal portions of .1 kilograms each and utilized in the preparation of the final red, green, and blue sensitive emuls ons.
Red sensitive To the first portion of a red sensitized wet gelatinosil-ver-halide emulsion there were added 5 grams of a rbleachable cyan dye, Direct Sky Blue -.(C.-I. #520) Green sensitive *I'o the'second portion of a green sensitized wet gelatino silver-halide emulsion there were added 1.25 grams of a bleachable magenta dye," Fast Acid Magenta B (C. I. #30).
Blue sensitive COATING The three final silver-halide emulsions, as above prepared, were coated to a dry thickness of approximately 6 microns upon a cellulose acetate film base (or other suitable support such as baryta coated paper) containing an anti-halo coating. The red sensitive silver-halide emulsion was coated first. Over this coating the green sensitive emulsion was coated followed by a coating of approximately 3 microns dry thickness of a yellow filter prepared in accordance with United States Patents 2,036,546; 2,220,187 or 2,390,707. Over the filter layer the blue sensitive emulsion was coated as the outermost layer.
PROCESSING The finishedfilm, prepared in accordance with the foregoing, was exposed and developed for 15 minutes in a black and white developer of the following composition:
Water cc 750 Metol ams" 1.5 Sodium sulfite (anhydrous) do 80 Hydroquinone do 3 Potassium bromide "gram" 0.5 Water to make liter 1 Short stopped for 3 minutes in a bath of the following composition:
Sodium acetate grams 20 Acetic acid cc 10 Water to make liter -1 Fixed for 3 minutes in a solution of the following composition:
Water cm. 650 Hypo "grams" 240 Sodium sulfite (anhydrous) do 15 Acetic acid (28% aqueous solution) cc 45 Potassium alum grams 15 Water to make liter 1 The fixed film was then cut into 6 equal strips and the strips treated for 10-15 minutes in dye bleach baths of the following compositions:
I (a) Hydrochloric acid, conc cc.. '250 Water to make liter -1 No satisfactory bleaching action on the dyes was observed within 15-30 minutes.
I (b) To 1(a) cc. of a 0.1% aqueous solution of riboflavin was added. Appreciable bleaching of the dyes in all silver bearing areas took place.
II (a) Hydrochloric acid, conc cc 100 Potassium bromide grams 100 Water to make liter 1 '8 EXAMPLE II The bleaching treatment of Example I was repeated on the same fixed color"*film strips, with the exception that lumazine was substituted for alloxazine with similar results.
EXAMPLE III A halogen silver-bearing layer colored with diamine pure blue FF (Schultz Farbslofitabellen 1931, 7th ed. #308) was treated with a bleach solution of the following composition:
Hydrobromic acid cc 250 1,8-dimethylalloxazine gram .005 Water to make liter 1 The dye was completely bleached within 10-15 minutes.
While the present invention has been described in considerable detail with reference to certain preferred procedures, materials and uses, it :iS understood that the invention is not limited thereto, that numerous variations may be made in the procedures herein described, and that equivalent materials may be substituted. Thus, for example, azo dyes other than those specifically mentioned and utilized in the foregoing examples, may be bleached satisfactorily, provided they are or can be used in the preparation of multi-layer color ,film in which, after exposure, the dye images are obtained by the silver dye bleach process. Several hundreds of such dyes are known and further referenceto them or to their methods of preparation need not be mentioned herein. Accordingly, the scope of the invention is to be defined by the following claims.
I claim:
1. A dye bleach bath for producing a colored image in a photographic emulsion layer containing a bleachable azo dye and a silver image consisting of an aqueous solution of hydrochloric acid, ammonium chloride, potassium iodide and an accelerating amount of an agent selected from the group consisting of lumazines and alloxazines corresponding to the following general formulae:
wherein R and R1 represent a member selected from the class consisting of hydrogen, alkyl and aryl groups, R2 and R3 represent a member selected from the class consisting of hydrogen and methyl group, R2 always being hydrogen when R: is methyland R3 always being hydrogen when R2 is methyl; and Z represents the atoms necessary'to complete a member selected from the class consisting of aromatic and heterocyclic ring systems's- 2. A dye bleach bath according to claim 1 in which the accelerating agent is alloxazine.
3. A dye bleach bath according to claim 1 in which the accelerating agent is lamazine.
H N N R C=O l R1 /NH N C and wherein R and R1 represent a member selected from the class consisting of hydrogen, alkyl and 10 aryl groups, R2 and R3 represent a member selected from the class consisting of hydrogen and methyl group, R2 always being hydrogen when R3 is methyl and R3 always being hydrogen when R2 is methyl, and Z represents the atoms necessary to complete a member selected from the class consisting of aromatic and heterocyclic ring systems.
6. The process according to claim 5 in which the accelerating agent is alloxazine.
7. The process according to claim 5 in which the accelerating agent is lumazine.
8. The process according to claim 5 in which the accelerating agent is 7,8-dimethylalloxazine.
FRITZ W. H. MUELLER.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,758,752 Lierg May 13, 1930 2,145,960 Wheatley et a1 Feb. 7, 1939 2,183,395 Gaspar Dec. 12, 1939 2,221,793 Gaspar Nov. 19, 1940 2,261,608 Tishler et a1 Nov. 4, 1941 2,270,118 Gaspar Jan. 13, 1942 2,346,090 Staehle Apr. 4, 1944 2,410,025 Gaspar Oct. 29, 1946
Claims (1)
- 5. THE PROCESS OF PRODUCING A COLORED IMAGE IN AN EXPOSED AND DEVELOPED PHOTOGRAPHIC LAYER CONTAINING A SILVER IMAGE AND A BLEACHABLE AZO DYE WHICH COMPRISES BLEACHING SAID LAYER IN A BATH COMPRISING AN AQUEOUS SOLUTION OF A MINERAL ACID AND AN ACCELERATING AMOUNT OF AN AGENT SELECTED FROM THE GROUP CONSISTING OF LUMAZINES AND ALLOXAZINES CORRESPONDING TO THE FOLLOWING GENERAL FORMULAE:
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA474965A CA474965A (en) | 1948-03-27 | Lumazines and alloxazines as catalysts in dye bleach baths for color photography | |
| BE488117D BE488117A (en) | 1948-03-27 | ||
| US17574A US2518710A (en) | 1948-03-27 | 1948-03-27 | Lumazines and alloxazines as catalysts in dye bleach baths for color photography |
| GB4278/49A GB657374A (en) | 1948-03-27 | 1949-02-16 | Lumazines and alloxazines as catalysts in dye bleach baths for color photography |
| CH285166D CH285166A (en) | 1948-03-27 | 1949-03-21 | Process for the production of colored images from tinted silver images. |
| CH279649D CH279649A (en) | 1948-03-27 | 1949-03-21 | Bleaching bath for color photography. |
| DEP37726A DE825206C (en) | 1948-03-27 | 1949-03-25 | Dye bleach bath for the production of colored images in photographic emulsion layers |
| FR983723D FR983723A (en) | 1948-03-27 | 1949-03-26 | Use of lumazines and alloxazines as catalysts in bleaching baths for color photography |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US17574A US2518710A (en) | 1948-03-27 | 1948-03-27 | Lumazines and alloxazines as catalysts in dye bleach baths for color photography |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2518710A true US2518710A (en) | 1950-08-15 |
Family
ID=21783357
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US17574A Expired - Lifetime US2518710A (en) | 1948-03-27 | 1948-03-27 | Lumazines and alloxazines as catalysts in dye bleach baths for color photography |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US2518710A (en) |
| BE (1) | BE488117A (en) |
| CA (1) | CA474965A (en) |
| CH (2) | CH285166A (en) |
| DE (1) | DE825206C (en) |
| FR (1) | FR983723A (en) |
| GB (1) | GB657374A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3156561A (en) * | 1958-06-03 | 1964-11-10 | Ciba Geigy Corp | Method of producing color photographic pictures |
| US3278303A (en) * | 1961-12-20 | 1966-10-11 | Ciba Ltd | Process for the preparation of multicolored images by the silver dyestuff bleaching method |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1758752A (en) * | 1927-02-07 | 1930-05-13 | Cutler Hammer Inc | Means for protecting contacts of electric switches |
| US2145960A (en) * | 1936-10-27 | 1939-02-07 | Wheatley Christopher Wi Crouch | Color photography |
| US2183395A (en) * | 1938-12-12 | 1939-12-12 | Gaspar Bela | Light-sensitive material for producing photographic dye images |
| US2221793A (en) * | 1938-05-17 | 1940-11-19 | Gaspar Bela | Method of producing photograph dyestuff pictures |
| US2261608A (en) * | 1940-03-21 | 1941-11-04 | Merck & Co Inc | Alloxazines and isoalloxazines and processes for their production |
| US2270118A (en) * | 1936-12-14 | 1942-01-13 | Chromogen Inc | Production of colored photographic pictures |
| US2346090A (en) * | 1942-08-19 | 1944-04-04 | Eastman Kodak Co | Photographic bleach-out layer |
| US2410025A (en) * | 1936-12-14 | 1946-10-29 | Chromogen Inc | Production of colored photographic pictures |
-
0
- BE BE488117D patent/BE488117A/xx unknown
- CA CA474965A patent/CA474965A/en not_active Expired
-
1948
- 1948-03-27 US US17574A patent/US2518710A/en not_active Expired - Lifetime
-
1949
- 1949-02-16 GB GB4278/49A patent/GB657374A/en not_active Expired
- 1949-03-21 CH CH285166D patent/CH285166A/en unknown
- 1949-03-21 CH CH279649D patent/CH279649A/en unknown
- 1949-03-25 DE DEP37726A patent/DE825206C/en not_active Expired
- 1949-03-26 FR FR983723D patent/FR983723A/en not_active Expired
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1758752A (en) * | 1927-02-07 | 1930-05-13 | Cutler Hammer Inc | Means for protecting contacts of electric switches |
| US2145960A (en) * | 1936-10-27 | 1939-02-07 | Wheatley Christopher Wi Crouch | Color photography |
| US2270118A (en) * | 1936-12-14 | 1942-01-13 | Chromogen Inc | Production of colored photographic pictures |
| US2410025A (en) * | 1936-12-14 | 1946-10-29 | Chromogen Inc | Production of colored photographic pictures |
| US2221793A (en) * | 1938-05-17 | 1940-11-19 | Gaspar Bela | Method of producing photograph dyestuff pictures |
| US2183395A (en) * | 1938-12-12 | 1939-12-12 | Gaspar Bela | Light-sensitive material for producing photographic dye images |
| US2261608A (en) * | 1940-03-21 | 1941-11-04 | Merck & Co Inc | Alloxazines and isoalloxazines and processes for their production |
| US2346090A (en) * | 1942-08-19 | 1944-04-04 | Eastman Kodak Co | Photographic bleach-out layer |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3156561A (en) * | 1958-06-03 | 1964-11-10 | Ciba Geigy Corp | Method of producing color photographic pictures |
| US3278303A (en) * | 1961-12-20 | 1966-10-11 | Ciba Ltd | Process for the preparation of multicolored images by the silver dyestuff bleaching method |
Also Published As
| Publication number | Publication date |
|---|---|
| CH279649A (en) | 1951-12-15 |
| BE488117A (en) | |
| FR983723A (en) | 1951-06-27 |
| CH285166A (en) | 1952-08-31 |
| CA474965A (en) | 1951-07-03 |
| GB657374A (en) | 1951-09-19 |
| DE825206C (en) | 1951-12-17 |
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