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
  • 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
  • G03C1/28—Sensitivity-increasing substances together with supersensitising substances
  • G03C1/29—Sensitivity-increasing substances together with supersensitising substances the supersensitising mixture being solely composed of dyes ; Combination of dyes, even if the supersensitising effect is not explicitly disclosed

Definitions

• This invention relates to a color photographic emulsion which is supersensitized by the use of two sensitizing dyes in combination. More particularly, the invention pertains to a light-sensitive silver halide color photographic emulsion incorporated with at least one sensitizing dye of the general Formula A shown below in combination with at least one sensitizing dye of the general Formula B also shown below.
• R is a lower alkyl group
• R is a hydrogen atom or a lower alkyl group
• R and R are independently selected from the group consisting of a lower alkyl group and alkyl substituted by a sulfonic acid, carboxylic acid or hydroxyl group,
• supersensitization is a means for enhancing the spectral sensitivity of a light-sensitive photographic layer by using, in combination with the main sensitizing dye, a dye or non-dye compound different in chemical structure from said main sensitizing dye.
• Sensitizing dyes used for the supersensitization of photographic silver halide emulsions are required to satisfy the following requirements:
• the object of the present invention is to provide a light-sensitive silver halide color photographic emulsion supersensitized by the use of sensitizing dyes which satisfy the above-mentioned requirements and, particularly, do not bring about any deletrious effects in photographic characteristics such as fogging and desenitization even when they are present together with anionic compounds, which are gelatine-coagulants (precipitating agents) or magenta couplers.
• the kind of sensitizing dyes which are used in the known sensitization processes, have such drawbacks, in the case where lower alkyl groups have been substituted on all the nitrogen atoms of the heterocyclic rings [eg in the cases of the control dyes (12) and (13) mentioned below], that when used together with incorporated color couplers, they cause an increase of fog and a decrease of color sensitivity during storage of films to deteriorate the photographic characteristics of the films, in most cases.
• the combination of sensitizing dyes employed in the present invention is characterized by using, as the main dye, an oxacarbocyanine having sulfoalkyl groups substituted in the nitrogen atoms on the heterocyclic rings, as seen in the aforesaid general Formula A. It has been found that by using said combination, there are displayed such excellent photographic characteristics as are mentioned above.
• sensitizing dyes represented by the general Formulas A and B are enumerated below, but the sensitizing dyes usable in the present invention are by no means limited thereto.
• Typical of the sensitizing dyes of the general Formula A are as follows:
• these sensitizing dyes may be added to photographic silver halide emulsions at any time during the course of the preparation of the emulsions. Generally, however, it is preferable to add them immediately after the second ripening.
• the amount of the dyes to be added varies depending on the kind of silver halide emulsion. Ordinarily,
• the total amount of the combination of the sensitizing dyes represented by the aforesaid general Formulas A and B is 3020O mg. per kg. of the silver halide emulsion.
• the silver halide emulsion may be sensitized.
• the amount of the sensitizing dye represented by the general Formula B is preferably 1-20% of the total amount.
• Silver halide emulsions employed in the present invention are color photographic emulsions containing incorporated color couplers capable of forming magenta color dyes.
• Usable silver halide emulsions include silver iodobromide, silver chlorobromide, silver bromide and silver chloride emulsions. Particularly, the use of silver iodobromide emulsion is preferable.
• These silver halide emulsions may have been sensitized with noble metal sensitizers, sulfur sensitizers, reduction sensitizers or polyalkylene oxide type sensitizers, and may have been incorporated with such known additives as stabilizers, surface active agents, hardeners, etc.
• the thus obtained emulsion was uniformly coated on a cellulose triacetate film support and was then dried to prepare a sample.
• the sample was exposed to 160 Lux daylight (5400 K.) through a green filter having a maximum transmission of 525 m from a Model KS-l sensitometer (manufactured by Konishiroku Photo Industry Co., Ltd., Japan) and was then subjected to color development at 20 C. for minutes, using a color developer of the following composition:
• the sample was subjected to ordinary bleaching, fixing and water-washing treatments, and was measured in fog and green light sensitivity to obtain the results as shown in Table 1.
• the sensitivity value in the table is represented by the relative green light sensitivity of the sample as measured by assuming that the green light sensitivity attained by the independent use of the dye (3) is 100.
• the sensitivity value in the table represents the relative sensitivity of each sample as measured by assuming that the green light sensitivity of the fresh control sample is 100.
• Control dye (14) 60 cc
• EXAMPLE 2 The same high speed silver iodobromide emulsion as in Example 1 was divided into several portions. To each portion of the emulsion, 0.1% methanol solutions of combinations of the present sensitizing dyes represented by the aforesaid general Formulas A and B were individ- EXAMPLE 3 The same high speed silver iodobromide emulsion as in Example 1 was divided into several portions. To each 5 portion of the emulsion, combinations of 0.1% methanol solutions of the present sensitizing dyes represented by the general Formulas A and B were individually added in amounts shown in the Table 3 per kg. of the emulsion.
• the sensitivity value in the table represents the relative sensitivity of each sample as measured by assuming that the green light sensitivity of a combination of the control dyes is 100.
• each mixture was charged with an optimum amount of a stabilizer and was then mixed according to a known procedure with 1 (3-carboxyphenyl) 3 (4-stearoylaminophenyl)-5-pyrazolone as a magenta coupler, and the mixture was adjusted to pH 6.8 to prepare a green light-sensitive, reversal color photographic emulsion.
• the thus obtained emulsions were uniformly coated individually on a cellulose triacetate film support to prepare samples. Further, there were also prepared stored samples in such a manner that the samples were individually stored for 3 hours at a temperature of 55 C. and for 3 days at a temperature of 50 C. and
• Example 2 the samples were exposed in the same manner as in Example 1 and were developed at 20 C. for 10 minutes with a developer of the following composition:
• the thus treated samples were measured in sensitivity and fog (residual color density) to obtain the results shown in Table 4.
• the sensitivity value in the table is the relative sensitivity of each sample as measured by assuming that the green light sensitivity of the control sample is 100.
• Relative Relative Relative green light green light green light sensitizing dye (0.1% methanol solution, (xx/kg. emulsion) sensitivity Fog l sensitivity Fog 1 sensitivity Fog 1 Dye exemplified by (3), 60 (20-. Dye exemplified by (7), 3 cc 140 0. 14 135 0. 15 135 0. 15
• the light-sensitive photographic silver halide emulsions of the present invention are high in green light sensitivity of magenta coupler layer and less in residual color density as compared with the control sample [control dye (14) control dye (15)] and that they are not decreased in color sensitivity even when subjected to severe storage tests.
• a light-sensitive silver halide color photographic emulsion which contains at least one sensitizing dye of the general 'Formula A shown below in combination with at least one sensitizing dye of the general Formula B shown below:
• Y is a hydrogen atom or a methyl group with the proviso that Y is a methyl group when Y is a chlorine atom, or
• Y and Y may form a benzene ring
• Z is a group necessary to form a thiazole, thiazoline, benzothiazole or benzoselenazole ring, or an alkyl or alkoxy derivative thereof,
• X is an acid anion
• n is an integer of 2 to 4, and
• m l or 2.
• -A light-sensitive silver halide color photographic element which comprises a film support and, coated thereon, a layer of the emulsion as claimed in claim 1.

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• Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)

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Cited By (9)

• 1969
  • 1969-05-28 US US828750A patent/US3580724A/en not_active Expired - Lifetime
  • 1969-05-30 GB GB1231362D patent/GB1231362A/en not_active Expired
  • 1969-06-03 DE DE19691928295 patent/DE1928295A1/de active Pending

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