US2592243A - Method of selectively exposing the grains of a mixed grain photographic emulsion - Google Patents

Method of selectively exposing the grains of a mixed grain photographic emulsion Download PDF

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Publication number
US2592243A
US2592243A US57592A US5759248A US2592243A US 2592243 A US2592243 A US 2592243A US 57592 A US57592 A US 57592A US 5759248 A US5759248 A US 5759248A US 2592243 A US2592243 A US 2592243A
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United States
Prior art keywords
grains
sensitized
dye
red
silver halide
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Expired - Lifetime
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US57592A
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English (en)
Inventor
Burt H Carroll
Jr Wesley T Hanson
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Eastman Kodak Co
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Eastman Kodak Co
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Priority to BE491769D priority Critical patent/BE491769A/xx
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
Priority to US57592A priority patent/US2592243A/en
Priority to FR1017762D priority patent/FR1017762A/fr
Priority to GB27762/49A priority patent/GB702200A/en
Priority to GB18311/52A priority patent/GB702255A/en
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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
    • G03C7/30—Colour processes using colour-coupling substances; Materials therefor; Preparing or processing such materials
    • G03C7/3041—Materials with specific sensitometric characteristics, e.g. gamma, density
    • 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
    • G03C1/12—Methine and polymethine dyes

Definitions

  • This invention relates to photography and particularly to a method of sensitizing and processing mixed grain photographic emulsions.
  • Diffusion of dye from sensitized to unsensitized or differently sensitized grains must take place through distances of the order of the thickness of the emulsion coatings and at low temperature.
  • sensitized and unsensitized grains are mixed in the liquid emulsion at temperatures of the order of 35 to 40 C. If the mixed grain emulsion were to be allowed to stand indefinitely, it would in all cases reach an'equilibrium in which the-distribution of all dyes was uniform over the surface of .all grains, except for such minor differences as would be produced by the differences in composition (for example, proportion of silver iodide) of the grains. In practice, only a rate of. diffusion low enough to be negligible during the period of coating and drying can be expected. Very few optical sensitizing dyes meet this requirement.
  • the remaining grains may be exposed to blue light and developed to a yellow image.
  • the diffusion of a very small amount of sensitizer is serious because even weak sensitization of the grains to a color difierent from the desired one, for example, red sensitization of green-sensitive grains, will make a considerable proportion of them developable when the film is given the heavy uniform exposure necessary to make all grains of another type developable.
  • many greensensitized grains might be fogged by the uniform flash with red light and hence developed cyan instead of magenta, if re d sensitizer had diffused. The effect is the more pronounced because a small amount of sensitizing dye gives a sensitizing effect more than proportional to its concentration when compared with the effect of the amounts usual for full sensitization.
  • a further object is to provide a procedure for processing mixed grain emulsions sensitized according to our method.
  • Still further object is to provide a method for minimizing the effect of sensitizing dye diffusion in mixed grain processes.
  • Such sensitizing dyes are normally used in concentrations which give the aggregate or second maximum at thelonger wave length. If such a dye diffuses slightly, the result is a sensitization of the other grains by a low concentration of. the dye. It accordingly sensitizes in the region of the maximum at shorter wave length when it diffuses.
  • a filter which absorbs the light of the region to which the grains are sensitized by the diffused dye. This is possible because of the difference of approximately 50 millimicrons between the sensitizing maximum of the dye at high concentration and at low concentration. The exposure therefore may be limited to the grains which it was intended to expose and excluded from those grains which have been unintentionally sensitized by the diffusing dye.
  • one of the optical sensitizing dyes used in our process has its absorption maximum in alcohol at 575 millimicrons. At low concentration it sensitizes with a maximum at 600 millimicrons. At higher concentrations, for example, at 0.13 gram per mole of silver halide in a moderate speed emulsion (about 28 milligrams per liter of emulsion) it sensitizes with a maximum at 675 millimicrons.
  • this dye is used in a mixed grain color process, the diffusion from the red-sensitive grains to the others is slight, but nevertheless sufficient to degrade the color rendering if the red light exposure after the first development in the case of a reversal process is made with a filter of the type commonly used for tricolor separations, that is, one transmitting all wave lengths of the visible spectrum greater than 600 millimicrons.
  • a filter of the type commonly used for tricolor separations that is, one transmitting all wave lengths of the visible spectrum greater than 600 millimicrons.
  • an appreciable proportion of the grains originally unsensi- .difiused dye is negligible at 650 millimicrons or longer, while the grains originally sensitized with the dye .have strong sensitivity at 675 millimicrons.
  • Dyes of the following classes are suitable for use according to our invention (1)
  • Carbocyanines derived from p-naphtho- -thiazole substituted in the central position of the chain by alkyl or aryl groups (Brooker U. S. Patent 1,846,301). These include 3,3 dimethyl 9 ethyl 4,5,4',5' dibenzthiacarbocyanine chloride 3,3 dimethyl 9 phenyl 4,5,4,5' dibenzthiacarbocyanine bromide 3,3,9 triethyl 4,5,4',5' dibenzthiacarbocyanine bromide.
  • Corresponding dyes from B-naphthiazole nuclei substituted in the nucleus by halogen, alkyl or Ialkoxy may also be used and the alkyl groups on the 3-positions may be replaced by hydroxyalkyl or'carboxyalkyl and the aryl group in the 9-position may be substituted by alkyl, halogen, or alkoxy. These are red sensitizers.
  • Carbocyanines derived from substituted benzothiazole or benzoselenazole nuclei substituted in the central position of the chain by alkyl or aryl groups for example, 3,3',9-triethyl-5,5'- dichloroselenacarbocyanine bromide (made by the method of White U. S. Patent, 1,990,681, using 5 chloro 2 methylbenzoselenazole instead of z-methylbenzoselenazole). These are red sensitizers.
  • Certain 2-cyanines for example, 1,3-diethyl-5-phenyl-6-methoxy thia-2'-cyanine bromide (Van Zandt & Brooker U. S. application Serial No. 711,816, now Patent No. 2,515,913), and 1',3 diethyl 4,5 benz-6'-methylthia-2'-cyanine bromide (Brooker U. S. Patent 1,935,696). These are green sensitizers.
  • optical sensitizing dyes are used according to our invention at a concentration of from 7 to 50 milligrams of sensitizing dye per liter of silver halide emulsion containing about 0.25 gram mole of silver halide per liter of emulsion. We prefer to use from 60 to milligrams of sensitizing dye per gram mole of silver halide.
  • the optical sensitizing dyes used according to our invention will produce a different sensitizing maximum at high concentration than at low concentration.
  • this difierence is due to an aggregate form of the sensitizing dye at high concentration and the molecular form of the dye at low concentration.
  • high concentration we mean the concentration of sensitizing dye which is present on the silver halide grain when used in the range of from 30 milligrams of sensitizing dye per gram mole of silver halide upward.
  • the effective amount of dye depends to some extent on the type of emulsion and composition of the dye itself, as indicated by the following examples.
  • low concentration we mean the form which the dye takes when it diffuses through a silver halide emulsion and becomes attached to silver halide grains which were not present in the emulsion when the sensitizing dye was added, as by mixing sensitized and unsensitized portions of the emulsion.
  • Eazample 1 A gelatino-silver bromoiodide emulsion containing 0.24 gram mole of silver bromoiodide per liter was divided into two equal portions. To one portion there was added an alcoholic solution of the red sensitizer 3,3'-dimethyl-9-ethyl- 4,5,4-dibenzthiacarbocyanine chloride, 20 milligrams of dye being added per liter of emulsion. The emulsion was heated to 50 C. and cooled to the coating temperature of approximately 38 C.
  • the neutral scale was in var-.- ious densities of blue, that is, cyan plus magenta.
  • the area exposed to red light varied from blue to magenta with increasing red exposure.
  • the area exposed to green light varied from blue to cyan with increasing exposure and the area exposed to blue light varied from blue to white.
  • a spectrogram made from this emulsion showed in the vicinity of 600 millimicrons a small area which was white, indicating that the grains were sensitive both to red and green. Its existence showed that the green-sensitive grains were slightly red-sensitive as the result of diffusion of traces of red-sensitizing dye. This region extends from about 550 to 630 millimicrons.
  • a single layer coating of this type can be converted into a complete three-color coating by overcoating it with an unsensitized emulsion of higher contrast containing a bleachable or otherwise removable yellow dye.
  • This coating is processed in the same manner except that after step 12 there is an exposure to blue light and development in a yellow coupler developer.
  • Chlorobromide emulsions having sensitivity effectively limited to the violet end of the spectrum are desirable for the red and green sensitive components in this case.
  • the blue .sensitive component may be either a bromoiodide emulsion, or a chlorobromide with optical sensitization. If the blue sensitized chlorobromide emulsion is used, the sensitizer must be nondifiusing only to the extent necessary for color separation in the image exposure of the film.
  • the two layer three-color coatings using a yellow-dyed second coat may be used as camera films or for printing of normal color originals.
  • the single-layer three-color coatings must be exposed through a filter absorbing all radiation to which the un-sensitized chlorobromide emulsion is sensitive. With very low proportions of bromide, this may be a filter such as the Wratten 2A, absorbing radiation of wavelengths less than 420 m but such emulsions are generally quite slow and there is more difliculty with diffusion of sensitizers.
  • Such films may be exposed from separation positives through appropriate filters, or may be used to make prints from colored originals in which the positions of the absorption maxima of the dyes were displaced to longer wavelengths than is normal.
  • Figure 1 is a reproduction of a wedge spectrogram in color of a coating similar to that described in Example 1.
  • the blue spectral region up to about 460 m varies from blue in the regions of low exposure (at the top of the spectrogram) to white in the regions of high exposure.
  • the spectrogram varies from blue in the regions of low exposure to cyan in the region of high exposure.
  • the spectrogram is blue in the regions of low exposure.
  • the red exposure region from about 640 to 700 m is magenta in the high exposure region.
  • regions from about 500 to 540 m and 580 to 640 m there is a white region. These regions indicate that the silver halide grains were exposed by both red and green light.
  • the region at 500 to 540 m indicates wandering of the green sensitizing dye and the region at 580 to 640 m indicates wandering of the red sensitizing dye.
  • These regions show that the red sensitive rains were slightly green sensitive as the result of diffusion of traces of green sensitizing dye and the green sensitive grains were slightly red sensitive as the result of diffusion of traces of red sensitizing dye.
  • sensitizing dyes had been used in this coating, which sensitized the grains to which they diiiused in the same region as to that which the originally sensitized grains were sensitive, it is apparent that the regions which are white in the spectogram would have extended throughout the green and red regions respectivelyand would have diluted the colors in these regions.
  • a filter can be used for the red light re-exposure which iransmits only that light having wavelengths longer than 640 Ill 1.. Below 640 m there is no transmission by this filter and the region of 580 to 640 m to which the diffusing red sensitizing dye sensitizes, is not exposed.
  • a filter in re-exposing the emulsion to green light, a filter can be used, such as that shown in Figure 3 of the drawing which transmits only that light having wavelength longer than about 520 n'l L. Light below this wavelength is not transmitted and for this reason, there is no green light exposure of the region around 520 m, to which the difiusing green sensitizing dye sensitizes.
  • Example 2 A gelatino-silver bromoiodide emulsion was sensitized as in Example 1 with milligrams per gram mole of silver halide of 3,3-dimethyl-8,l0- toloxythiacarbocyanine bromide as the red sensitizer and 85 milligrams per gram mole of silver halide of 1',3-diethyl-4,5-benz-6-methylthia-2- cyanine bromide as the green sensitizer. It was exposed and processed as in Example 1 except that a Wratten No. 29 filter transmitting wave lengths longer than 610 millimicrons was used instead of Wratten No. '70 filter for the red reexposure.
  • Example 3 A gelatino-silver chlorobromide emulsion approximately 60% silver chloride and 40% silver bromide containing 0.30 gram moles of silver halide per liter was used. One-half of this emulsion was sensitized with 18 milligrams per liter of emulsion of 3,3-dimethyl-9-phenyl-4,5,4,5- dibenzthiacarbocyanine chloride as the red sensitizer. The other half was sensitized with 25 milligrams per liter of emulsion of 3.3',9-triethyl- 5,5-diphenyloxacarbocyanine bromide (U. S. Patent 2,295,276) as the green sensitizer. The mixedemulsion was exposed and processed as in Example 1 except that the black and white dev op e t (St p 3) was for two minutes instead of 8 minutes. Color separation was satisfactory.
  • St p 3 black and white dev op e t
  • Example 4 An emplsion like that of Example 3 was used. One-third of the emulsion was red sensitized as in Example 3, and one-third green sensitized as in Example 3. The remaining third was sensitized to the blue (maximum at 470 m by adding 25 mg. per liter of 3,3-diethyl-6,I,6,'7'-dibenzthiacyanine chloride (J. Chem. Soc. 1930, page 2508), heating to 50 C. for five minutes, cooling to 35 before mixing with the red and green sensitive portions. It was exposed for formation of the image to red light (Wratten No. 29 filter), green light (Wratten N0. 58 filter) and blue light (Wratten No. 49 and No. 3 filters, the latter to prevent exposure of the red and green sensitive grains). Processing was similar to that of Example 3 except that after step 12 it was exposed uniformly to white light and developed for 10 minutes in a yellow coupler developer of the following composition:
  • our invention consists of two principal features (1) the use in mixed grain emulsions for color processes of a sensitizing dye which at low concentrations has a maximum of sensitization appreciably shorter than that which is characteristic of the normal concentration used in sensitizing the grains and (2) exposure of the emulsion at appropriate steps in the process by radiation corresponding to the normal maximum of sensitization and excluding or minimizing that corresponding to sensitization by low concentrations of dye which has diffused to other grains.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Silver Salt Photography Or Processing Solution Therefor (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
US57592A 1948-10-30 1948-10-30 Method of selectively exposing the grains of a mixed grain photographic emulsion Expired - Lifetime US2592243A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE491769D BE491769A (en, 2012) 1948-10-30
US57592A US2592243A (en) 1948-10-30 1948-10-30 Method of selectively exposing the grains of a mixed grain photographic emulsion
FR1017762D FR1017762A (fr) 1948-10-30 1949-10-28 Nouvelle émulsion photographique sensibilisée à grains mixtes, son procédé de traitement et produits en résultant
GB27762/49A GB702200A (en) 1948-10-30 1949-10-29 Improvements in mixed grain colour photography
GB18311/52A GB702255A (en) 1948-10-30 1949-10-29 Improvements in mixed grain photographic emulsions and sensitive materials employingthem

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Application Number Priority Date Filing Date Title
US57592A US2592243A (en) 1948-10-30 1948-10-30 Method of selectively exposing the grains of a mixed grain photographic emulsion

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BE (1) BE491769A (en, 2012)
FR (1) FR1017762A (en, 2012)
GB (2) GB702255A (en, 2012)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2676103A (en) * 1950-03-18 1954-04-20 Fr Corp Process and composition for use in color photography
DE971466C (de) * 1951-10-17 1959-01-29 Eastman Kodak Co Verfahren zur Verhinderung der Diffusion von Sensibilisatoren in gemischtkoernigen Emulsionen
DE1113873B (de) * 1959-01-17 1961-09-14 Wolfen Filmfab Veb Verfahren zur Sensibilisierung von Halogensilberemulsionen
DE2528638A1 (de) * 1974-06-26 1976-01-15 Minnesota Mining & Mfg Pivalylacetanilide und diese verbindungen enthaltendes photographisches aufzeichnungsmaterial
EP0849623A3 (en) * 1996-12-18 1999-04-21 Eastman Kodak Company Photographic high contrast silver halide material

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3992210A (en) * 1973-06-05 1976-11-16 E. I. Du Pont De Nemours And Company Silver halide films with controlled gradient balance

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1980941A (en) * 1927-11-12 1934-11-13 Leopold D Mannes Color photography
US2252718A (en) * 1937-11-19 1941-08-19 Eastman Kodak Co Reversal process of color photography
US2318597A (en) * 1941-01-03 1943-05-11 Eastman Kodak Co Photographic printing material
US2320418A (en) * 1935-06-22 1943-06-01 Gen Aniline & Film Corp Color photographs
US2388859A (en) * 1940-01-11 1945-11-13 Eastman Kodak Co Mixed grain emulsions

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1980941A (en) * 1927-11-12 1934-11-13 Leopold D Mannes Color photography
US2320418A (en) * 1935-06-22 1943-06-01 Gen Aniline & Film Corp Color photographs
US2252718A (en) * 1937-11-19 1941-08-19 Eastman Kodak Co Reversal process of color photography
US2388859A (en) * 1940-01-11 1945-11-13 Eastman Kodak Co Mixed grain emulsions
US2318597A (en) * 1941-01-03 1943-05-11 Eastman Kodak Co Photographic printing material

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2676103A (en) * 1950-03-18 1954-04-20 Fr Corp Process and composition for use in color photography
DE971466C (de) * 1951-10-17 1959-01-29 Eastman Kodak Co Verfahren zur Verhinderung der Diffusion von Sensibilisatoren in gemischtkoernigen Emulsionen
DE1113873B (de) * 1959-01-17 1961-09-14 Wolfen Filmfab Veb Verfahren zur Sensibilisierung von Halogensilberemulsionen
DE2528638A1 (de) * 1974-06-26 1976-01-15 Minnesota Mining & Mfg Pivalylacetanilide und diese verbindungen enthaltendes photographisches aufzeichnungsmaterial
EP0849623A3 (en) * 1996-12-18 1999-04-21 Eastman Kodak Company Photographic high contrast silver halide material

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GB702200A (en) 1954-01-13
GB702255A (en) 1954-01-13
BE491769A (en, 2012)
FR1017762A (fr) 1952-12-18

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