US3305363A - Photographic development promoters - Google Patents
Photographic development promoters Download PDFInfo
- Publication number
- US3305363A US3305363A US237382A US23738262A US3305363A US 3305363 A US3305363 A US 3305363A US 237382 A US237382 A US 237382A US 23738262 A US23738262 A US 23738262A US 3305363 A US3305363 A US 3305363A
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- United States
- Prior art keywords
- silver halide
- acid
- developer
- photographic
- emulsion
- 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
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
- C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
- C07D307/34—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
- C07D307/56—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D307/60—Two oxygen atoms, e.g. succinic anhydride
-
- 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
- G03C1/00—Photosensitive materials
- G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
- G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
- G03C1/08—Sensitivity-increasing substances
- G03C1/10—Organic substances
-
- 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
- G03C1/00—Photosensitive materials
- G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
- G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
- G03C1/42—Developers or their precursors
-
- 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
- G03C5/29—Development processes or agents therefor
- G03C5/30—Developers
Definitions
- This invention relates to photography.
- it relates to use of certain compounds as development promoters with photographic. developers.
- An object of the invention is to provide a new use for compounds :as development promoters in photographic development proceses.
- One specific object is to provide photographic silver halide emulsions having incorporated therein compounds that will act as development promoters when placed in alkaline solution in the presence of an organic silver halide developer.
- enediol lactone compounds as agents for silver halide development is known (see, for example, US. Patents 2,688,548 and 2,688,549 to Reynolds et -al.).
- the present invention provides compounds that have an accelerating or super-additive effect when used with silver halide developers, similar to the effect of enediol lactones but that have no independent developing activity. Instead of the characteristic active enediol group of enediol lactone class of promoters, the present compounds have a less active enol group.
- R is a member selected from the group consisting of H, Cl, and Br
- R is a member selected from the group consisting of H, alkyl containing 1-5 carbon atoms and aryl
- R is a member selected from the group consisting of 0x0 and imino
- X is a member selected from the group consisting of 0x0 and [-H, -OH].
- Enol lactones and dila-ctones of the class described are stable against oxidation when included in photographic silver halide emulsions which are acid. Such stability is an advantage not possessed by the enediol lactones. These stable promoters can be incorporated in acid silver halide emulsions with stable developers such as phenidone and the like. Specific examples of enediol lactones having the Formula I above are but can be considered equivalent in the present invention because they are stable in acid silver halide emul- 3,305,363 Patented Feb. 21, 1967 ice sions and they hydrolyze in alkaline solution, e.g. developer solution, to form an active enol lactone, e.g.
- these enol lactones show very little or no photographic developing action, even though they may retain some reducing activity as with Fehling solution.
- a developing solution containing a developer such as a 1-phenyl-3-pyrazolidone for example, or are incorporated in a silver halide emulsion which is eventually treated with a developing solution containing an organic developer, an acceleration or superadditive action is produced by means of the enol lactones.
- Compounds of the class described are useful as promoters in processes for silver halide development which comprise the step of washing an exposed film of silver halide emulsion with an alkaline solution in the presence of an organic silver halide developer and a promoter of the class described.
- the promoter is included in the photographic emulsion, as is described in the examples below, but our invention also includes processes in which a promoter of the class described is added directly in the alkaline developer solution.
- our invention includes processes in which all of the developer is incorporated in the emulsion and processes in which all of the developer is in the alkaline solution.
- Alpha-bromotetronic acid and a-chlorotetronic acid were prepared by the method described at J. Am. Chem. Soc, 60, 857-864 (1938).
- Tetronic acid was prepared as follows. To a solution of 20 grams of oz-bIOIIlOtCtlOIliC acid in ml. of methanol was added 9.5 g. of anhydrous barium hydroxide. The mixture was hydrogenated in a Parr apparatus at 50 psi. using 2.5 g. of palladium-charcoal catalyst. The hydrogenation was complete in about 15 minutes, at the end of which time all of the barium hydroxide had dissolved. The solution was filtered and evaporated to dryness in vacuum at room temperature. The residue was dissolved in a mixture of 25 ml. of water and 50 ml. of ether.
- D-mannosaccharo-1,423,6-dilactone was prepared as follows. A solution of 103 g. of D-mannose in 350 ml. of 1:1 by volume concentrated nitric acid and water was heated in a circulating water bath at 60 C. for
- Example I A conventional negative speed silver bromo-iodide emulsion was prepared for coating. The emulsion was divided into aliquot portions and solutions of the addenda Example 11 A conventional negative speed silver bromoiodide photographic emulsion was prepared as in Example I with the addenda shown in Table II and tested as in shown in Table I were added to each portion just before Example I. Results are shown in Table 11.
- Example III A conventional negative speed silver bromoiodide photographic emulsion was coated on lightweight paper stock with the addenda shown in Table III and tested in the manner indicated in Example I. Effects of the addenda are shown in Table III.
- stable organic silver halide developers suitable for incorporation in silver halide emulsions instead of those mentioned in the examples are 3-pyrazolidone developers such as those described in US. Patent No. 2,685,515 and other developers that are inactive and stable in neutral or acid emulsions.
- organic silver halide developers for use in the alkaline wash solution instead of those mentioned in the examples are: Elon-hydroquinone, hydroquinone-ascorbic acid, hydroquinone, various 3-pyrazolidone developers, and the like.
- the alkaline wash may consist simply of an alkaline solution, such as a solution of an alkali metal hydroxide or carbonate and the like.
- the emulsion composition is not a critical factor of the invention; any conventional acid silver halide emulsion that is useful for photographic film may be used within the scope of the present invention.
- the optimum concentration of promoter for best results usually will be in the range from to 200 grams per gram mole of silver halide, and in most cases from 40 to 80 grams per gram mole.
- a process of developing a latent image in an exposed photographic silver halide film comprising washing the exposed film with an alkaline solution in the presence of at least one organic silver halide developer and a promoter selected from the group consisting of compounds having the formulas and wherein R represents a member selected from the group consisting of H, C], and Br and X represents a member selected from the group consisting of 0x0 and Tetronic acid u-chlorotetronic acid a-bromotetronic acid D-mannosaccharo-1,4 3,6-dilact0ne D-glucuronolactone 6.
- An acid photographic silver halide emulsion having incorporated therein a stable organic silver halide developer and from 10 to 200 grams of promoter per gram mole of silver halide present, said promoter being a member selected from the group consisting of Tetronic acid wchlorotetronic acid a-bromotetronic acid D-mannosaccharo-1,4 3,6-dilactone D-.glucuronolactone References Cited by the Examiner UNITED STATES PATENTS 2,415,666 2/ 1947 Weissberger et al. 99-66 2,845,349 7/1958 Schwarz 9966 3,022,168 2/ 1962 Stjarnkvist 99-66 OTHER REFERENCES Micheel et al.: Berichte, vol. 67, pp. 166064 (1934).
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- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Organic Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Heterocyclic Carbon Compounds Containing A Hetero Ring Having Nitrogen And Oxygen As The Only Ring Hetero Atoms (AREA)
- Silver Salt Photography Or Processing Solution Therefor (AREA)
Description
United States Patent 3,305,363 PHOTOGRAPHIC DEVELOPMENT PROMOTERS Dorothy J. Beavers and Norman Allentofi, Rochester,
N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Nov. 13, 1962, Ser. No. 237,382 6 Claims. (Cl. 96-66.3)
This invention relates to photography. In particular, it relates to use of certain compounds as development promoters with photographic. developers.
, An object of the invention is to provide a new use for compounds :as development promoters in photographic development proceses. One specific object is to provide photographic silver halide emulsions having incorporated therein compounds that will act as development promoters when placed in alkaline solution in the presence of an organic silver halide developer.
Use of enediol lactone compounds as agents for silver halide development is known (see, for example, US. Patents 2,688,548 and 2,688,549 to Reynolds et -al.). The present invention provides compounds that have an accelerating or super-additive effect when used with silver halide developers, similar to the effect of enediol lactones but that have no independent developing activity. Instead of the characteristic active enediol group of enediol lactone class of promoters, the present compounds have a less active enol group.
Specifically, compounds useful according to the present invention as development promoters have the formulas:
X I] R 0 a drroH I-IOC H 1 0 d CH l at R -o o I II I CHOH 2 & H o
wherein R is a member selected from the group consisting of H, Cl, and Br, R is a member selected from the group consisting of H, alkyl containing 1-5 carbon atoms and aryl, R is a member selected from the group consisting of 0x0 and imino, and X is a member selected from the group consisting of 0x0 and [-H, -OH].
Enol lactones and dila-ctones of the class described are stable against oxidation when included in photographic silver halide emulsions which are acid. Such stability is an advantage not possessed by the enediol lactones. These stable promoters can be incorporated in acid silver halide emulsions with stable developers such as phenidone and the like. Specific examples of enediol lactones having the Formula I above are but can be considered equivalent in the present invention because they are stable in acid silver halide emul- 3,305,363 Patented Feb. 21, 1967 ice sions and they hydrolyze in alkaline solution, e.g. developer solution, to form an active enol lactone, e.g.
Specific examples of dilactones that are useful according to the invention are D-mannosaccharo-1,4:3,6-dil-actone (II, X=oxo) and D-glucuronolactone (H, X: [-H, -OH] The latter is commercially avail-able.
Unlike enediol lactones, these enol lactones show very little or no photographic developing action, even though they may retain some reducing activity as with Fehling solution. However, when these compounds are added to a developing solution containing a developer such as a 1-phenyl-3-pyrazolidone for example, or are incorporated in a silver halide emulsion which is eventually treated with a developing solution containing an organic developer, an acceleration or superadditive action is produced by means of the enol lactones. Compounds of the class described are useful as promoters in processes for silver halide development which comprise the step of washing an exposed film of silver halide emulsion with an alkaline solution in the presence of an organic silver halide developer and a promoter of the class described. Preferably the promoter is included in the photographic emulsion, as is described in the examples below, but our invention also includes processes in which a promoter of the class described is added directly in the alkaline developer solution. Although it is usually preferred to have one developer incorporated in the emulsion and a second developer in the alkaline solution as in the examples below, our invention includes processes in which all of the developer is incorporated in the emulsion and processes in which all of the developer is in the alkaline solution.
Alpha-bromotetronic acid and a-chlorotetronic acid were prepared by the method described at J. Am. Chem. Soc, 60, 857-864 (1938).
Tetronic acid was prepared as follows. To a solution of 20 grams of oz-bIOIIlOtCtlOIliC acid in ml. of methanol was added 9.5 g. of anhydrous barium hydroxide. The mixture was hydrogenated in a Parr apparatus at 50 psi. using 2.5 g. of palladium-charcoal catalyst. The hydrogenation was complete in about 15 minutes, at the end of which time all of the barium hydroxide had dissolved. The solution was filtered and evaporated to dryness in vacuum at room temperature. The residue was dissolved in a mixture of 25 ml. of water and 50 ml. of ether. The ether layer was separated and the aqueous phase was extracted with four 50-mlpportions of ether. The combined ether solution was dried with anhydrous sodium sulphate and evaporated. A yield of 9.7 g. (87%) of crude tetronic acid was obtained. This was recrystallized from a mixture of absolute ethanol and ligroin giving a product melting at 142-143 C. with decomposition.
D-mannosaccharo-1,423,6-dilactone was prepared as follows. A solution of 103 g. of D-mannose in 350 ml. of 1:1 by volume concentrated nitric acid and water was heated in a circulating water bath at 60 C. for
seconds at 32 C. in Kodak D-19-b developer having the following formula:
5 hours. During this time a vigorous reaction took place Grams with evolution of nitrous oxide fumes. The solution was 5 E1011 2.2 then heated in a bath at 85 C. for one hour and evap- Hydroquinone 8.8 orated in a shallow dish at about 90 C. while being Sodium sulfite (anhydrous) 72.0 stirred with a strong jet of air. The residue Was removed Sodium carbonate (anhydrous) 48.0 and dried overnight in a vacuum desiccator over solid Potassium bromide 4.0
Water to 1 liter.
After development the papers were fixed, washed and dried. Relative speed was measured at reflection densities of 0.1 above fog. The effects of the addenda on fog, speed D and stability of the emulsion are shown in the following table. Also shown is the fog density found in a sample of each coated paper after incubation of the coated paper for eight days at 120 F., relative humidity.
TABLE I Fog Addenda, Relative Addenda gmJgm. speed, 0.1 Reflection, Contrast mol. AgX After above fog m above fog Fresh 8 day incuba.
Control 0.02 0.02 100 1.18 0.79 l-phenyl3-pyrmnlidone 20 0. O3 0. 38 182 1. 22 0. 92 Ascorbic acid 80 0.32 0.83 115 1. 21 0.60-0.70 l-phenyl-B-pyrazolidone plus ascorbic acid 0.17 0.83 200 1. 23 0. 00 1-pl1enyl-3-pyrazolidone plus D-mannosaecharodilactone. 0. 01 0.06 240 1. 18 1. 10 1-pl1enyl-3-pyrazolidone plus a-bromotetronie acid 0.09 0.02 229 1. 20 0. 00
Example I A conventional negative speed silver bromo-iodide emulsion was prepared for coating. The emulsion was divided into aliquot portions and solutions of the addenda Example 11 A conventional negative speed silver bromoiodide photographic emulsion was prepared as in Example I with the addenda shown in Table II and tested as in shown in Table I were added to each portion just before Example I. Results are shown in Table 11.
TABLE II Fog Addenda, Relative Reflection, Contrast Addenda gJm. speed, 0.1 max above [0g AgX 8 day above log Flesh incuba.
Control 0. 01 0. 02 100 1. 16 0. 77 1-pheny1-4-1nethyl3-pyrazolidone 20 0. 01 0. 106 1. 20 O. 98 1-phenyl-4-methyl-B-pyrazolidone plus glucuronolactone 0.02 0. 04 190 1. 22 1. 11
1 Shoulder speed very high. Better incubation characteristics than control or l'pheny-4-n1ethyl-3-pyrazolidone alone.
coating. A portion of each preparation was coated by a conventional coating method on light weight paper stock (not baryta coated) in an amount equivalent to 150 mg. of silver per square foot and dried. After sensitometric exposure the papers were developed for 25 Example III A conventional negative speed silver bromoiodide photographic emulsion was coated on lightweight paper stock with the addenda shown in Table III and tested in the manner indicated in Example I. Effects of the addenda are shown in Table III.
TABLE 111 Fog Addenda, Relative Reflection, Contrast Addenda gmJgm. Speed, 0.1 above tog mol. AgX 8 day above fog Fresh Incuba.
Control-.. 0.01 0.02 100 1.14 0. l-phenyl-(i-pymmlidnne 20 0. O4 0. O9 204 1. 20 1. 2O l-phenyl-S-pyrazolidone plus D-mannosaccl1arodilactone 0.05 0. 24 203 1. 22 1. 38 Do 0. 04 o. 25 302 1. 22 1. 2c
As indicated by data in Tables I, II, and III, the presence of a promotor of the class described increases the speed and contrast of emulsions in which it is incorporated.
Some examples of stable organic silver halide developers suitable for incorporation in silver halide emulsions instead of those mentioned in the examples are 3-pyrazolidone developers such as those described in US. Patent No. 2,685,515 and other developers that are inactive and stable in neutral or acid emulsions.
Some examples of organic silver halide developers for use in the alkaline wash solution instead of those mentioned in the examples are: Elon-hydroquinone, hydroquinone-ascorbic acid, hydroquinone, various 3-pyrazolidone developers, and the like. When an organic developer is incorporated in the emulsion the alkaline wash may consist simply of an alkaline solution, such as a solution of an alkali metal hydroxide or carbonate and the like.
Beyond the requirement that a silver halide emulsion must be acid to be compatible with incorporated promoters, the emulsion composition is not a critical factor of the invention; any conventional acid silver halide emulsion that is useful for photographic film may be used within the scope of the present invention.
When the promoter is incorporated in a silver halide emulsion, the optimum concentration of promoter for best results usually will be in the range from to 200 grams per gram mole of silver halide, and in most cases from 40 to 80 grams per gram mole.
The invention has been described with reference to certain preferred embodiments and it will be understood that modifications and variations may be made within the scope of the invention as described above and as defined in the following claims.
We claim:
1. A process of developing a latent image in an exposed photographic silver halide film, comprising washing the exposed film with an alkaline solution in the presence of at least one organic silver halide developer and a promoter selected from the group consisting of compounds having the formulas and wherein R represents a member selected from the group consisting of H, C], and Br and X represents a member selected from the group consisting of 0x0 and Tetronic acid u-chlorotetronic acid a-bromotetronic acid D-mannosaccharo-1,4 3,6-dilact0ne D-glucuronolactone 6. An acid photographic silver halide emulsion having incorporated therein a stable organic silver halide developer and from 10 to 200 grams of promoter per gram mole of silver halide present, said promoter being a member selected from the group consisting of Tetronic acid wchlorotetronic acid a-bromotetronic acid D-mannosaccharo-1,4 3,6-dilactone D-.glucuronolactone References Cited by the Examiner UNITED STATES PATENTS 2,415,666 2/ 1947 Weissberger et al. 99-66 2,845,349 7/1958 Schwarz 9966 3,022,168 2/ 1962 Stjarnkvist 99-66 OTHER REFERENCES Micheel et al.: Berichte, vol. 67, pp. 166064 (1934).
James: Journal Photographic Science, vol. 6, pages 49-56 (1958).
NORMAN G. TORCHIN, Primary Examiner.
ABRAHAM H. WINKELSTEIN, Examiner.
J. T. BROWN, C. E. DAVIS, Ass stant Examiners.
Claims (1)
1. A PROCESS OF DEVELOPING A LATENT IMAGE IN AN EXPOSED PHOTOGRAPHIC SILVER HALIDE FILM, COMPRISING WASHING THE EXPOSED FILM WITH AN ALKALINE SOLUTION IN THE PRESENCE OF AT LEAST ONE ORGANIC SILVER HALIDE DEVELOPER AND A PROMOTER SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS HAVING THE FORMULAS
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| BE639787D BE639787A (en) | 1962-11-13 | ||
| US237382A US3305363A (en) | 1962-11-13 | 1962-11-13 | Photographic development promoters |
| FR953202A FR1374100A (en) | 1962-11-13 | 1963-11-08 | Process for accelerating the action of photographic developers |
| GB44328/63A GB1071674A (en) | 1962-11-13 | 1963-11-11 | Processes of photographic development |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US237382A US3305363A (en) | 1962-11-13 | 1962-11-13 | Photographic development promoters |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3305363A true US3305363A (en) | 1967-02-21 |
Family
ID=22893481
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US237382A Expired - Lifetime US3305363A (en) | 1962-11-13 | 1962-11-13 | Photographic development promoters |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US3305363A (en) |
| BE (1) | BE639787A (en) |
| GB (1) | GB1071674A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3382071A (en) * | 1964-06-24 | 1968-05-07 | Du Pont | Silver halide photographic element containing spot or streak prevention compounds |
| US3397984A (en) * | 1965-08-19 | 1968-08-20 | Eastman Kodak Co | Silver dye bleach materials improving image density |
| US3477849A (en) * | 1964-03-23 | 1969-11-11 | Eastman Kodak Co | Multi-color dye developer systems |
| US3649289A (en) * | 1968-10-21 | 1972-03-14 | Eastman Kodak Co | Photographic materials |
| US5008402A (en) * | 1988-09-06 | 1991-04-16 | Lonza Ltd. | Process for production of 5-alkyl tetramic acids |
| CN118791738A (en) * | 2024-09-14 | 2024-10-18 | 烟台三月科技有限责任公司 | Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2415666A (en) * | 1943-07-10 | 1947-02-11 | Eastman Kodak Co | Ascorbic acid in photographic developing solutions |
| US2845349A (en) * | 1955-09-07 | 1958-07-29 | Powers Chemco Inc | Photographic developers |
| US3022168A (en) * | 1958-06-28 | 1962-02-20 | Pharmacia Ab | Photographic developer |
-
0
- BE BE639787D patent/BE639787A/xx unknown
-
1962
- 1962-11-13 US US237382A patent/US3305363A/en not_active Expired - Lifetime
-
1963
- 1963-11-11 GB GB44328/63A patent/GB1071674A/en not_active Expired
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2415666A (en) * | 1943-07-10 | 1947-02-11 | Eastman Kodak Co | Ascorbic acid in photographic developing solutions |
| US2845349A (en) * | 1955-09-07 | 1958-07-29 | Powers Chemco Inc | Photographic developers |
| US3022168A (en) * | 1958-06-28 | 1962-02-20 | Pharmacia Ab | Photographic developer |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3477849A (en) * | 1964-03-23 | 1969-11-11 | Eastman Kodak Co | Multi-color dye developer systems |
| US3382071A (en) * | 1964-06-24 | 1968-05-07 | Du Pont | Silver halide photographic element containing spot or streak prevention compounds |
| US3397984A (en) * | 1965-08-19 | 1968-08-20 | Eastman Kodak Co | Silver dye bleach materials improving image density |
| US3649289A (en) * | 1968-10-21 | 1972-03-14 | Eastman Kodak Co | Photographic materials |
| US5008402A (en) * | 1988-09-06 | 1991-04-16 | Lonza Ltd. | Process for production of 5-alkyl tetramic acids |
| CN118791738A (en) * | 2024-09-14 | 2024-10-18 | 烟台三月科技有限责任公司 | Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element |
Also Published As
| Publication number | Publication date |
|---|---|
| BE639787A (en) | |
| GB1071674A (en) | 1967-06-14 |
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