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
  • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
• • 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
  • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
  • G03C2001/03523—Converted grains

Definitions

• the present invention relates to an improved process for the production of a photographic silver halide emulsion of enhanced sensitivity.
• a photographic silver halide emulsion is usually prepared by the following steps: 1) the emulsification of silver halide particles and the first ripening therefor, (2) the removal of excessive salts, and, (3) the second ripening.
• step 1) an aqueous silver nitrate solution is usually added to a solution containing dissolved therein a small amount of gelatin and a soluble halide to obtain emulsified silver halide particles and this procedure is generally called the single jet mixing method.
• the soluble halide to be employed may be a single kind of halide or a mixture of several kinds of halides, but the latter is suitable for obtaining an emulsion of a higher sensitivity. For example, it has been well known in the art that silver chloro-bromide has higher light sensitivity than silver chloride and silver iodo-bromide has higher light sensitivity than silver bromide.
• an object of the present invention is to provide a photographic silver halide emulsion for highsensitivity negative photographic elements.
• Another object of this invention is to provide a novel process for forming silver iodo-bromide particles.
• Still other objects of this invention is to provide a process for improving the characteristics of photographic, silver halide, light-sensitive elements.
• the inventor has found that by preparing a suspension ice of fine particles of silver iodide and gelatin in a state of the pesence of excessive silver ions and adding the suspension into an aqueous solution of a bromide, a highly light-sensitive, silver iodo-bromide emulsion containing the fine particles is obtained.
• a suspension (I) of fine silver iodide crystals is obtained.
• the amounts of the silver ions and the iodine ions to be added are selected such that 1-2O mol percent of thus added silver ions are converted into silver iodide.
• the gelatin to be employed in this invention is preferably of an inactive type. Thereafter, the resulting suspension is added slowly into an aqueous solution of an excessive amount of bromide with stirring to provide silver iodo-brornide particles (II).
• the fine crystals of silver iodide are continuously supplied together with silver ions and hence the silver iodide is distributed more uniformly among the particles and, by the conversion of crystals, the final silver iodo-bromide particles are formed.
• iodine ions will be consumed completely in the earlier period of the addition of the silver ions and accordingly, the distribution of silver iodide among the particles of silver iodo-bromide will tend to become uneven.
• the distribution of silver iodide among particles may be more uniform than the case of the single jet mixing method, there is difficulty in the growth of crystals in such a method, which makes the method unsuitable for the production of high-sensitivity silver halide emulsions.
• the distribution of silver iodide among the particles by a conventional double jet mixing method may be uniform to some extent, but it is not always possible to obtain completely uniform distribution of silver iodide.
• particles of silver iodo-bromide are formed by coprecipitation in each case. While, according to the process of the present invention, the distribution of silver iodide among particles can be made uniform as well as by using the silver iodide nuclei, silver iodo-bromide particles can be made which have properties different from those of the silver iodo-bromide particles prepared by conventional mixing methods.
• gelatin may be used, if necessary, and the gelatin may be an active type, although an inactive type is preferable, as mentioned above. Further, instead of gelatin, there may be employed in the process of this invention such synthetic high molecular materials as polyvinyl lactams, polyvinyl alcohols, and polyacrylamides.
• the light-sensitivity thereof is increased by conducting the first ripening, the removal of excessive salts, and, then, the second ripening as in the case of conventional mixing methods. It is preferable to conduct the second ripening in the presence of a small amount of a sulfur compound, a noble metal salt and a reducing material.
• the silver halide emulsion may be applied to a suitable support with the addition of a light-sensitive dye, a stabilizer, a hardening agent, and a wetting agent to provide a photographic silver halide light-sensitive element.
• Solution III Potassium bromide g 58.8 Inactive gelatin g 18 Distilled water to make ml 600 Temperature C 65 Into Solution III was added 300 ml. of the mixture of Solution I and Solution II within 30 seconds with stirring. Then the system was stirred for 4 minutes and 30 seconds. This procedure was repeated 4 times to add the whole proportion of the solution mixture (I-l-II) into Solution III. Then, after the addition of 140 g. of gelatin, the system was ripened by heating for 12 minutes at 65 C. Thereafter, the thus obtained emulsion was diluted to 2200 ml. and set by cooling. The product was shredded into noodles and washed with water until the electric conductivity thereof became 1,200 ,u.V./CII1.
• the thus prepared emulsion corresponding to g. of silver nitrate, was mixed with 4 ml. of an aqueous solution of 0.01% of Na S O -5H O, as a sulfur sensitizer, and a mixture of 2 ml. of an aqueous solution of 0.01% of HAuCl -4H O and 2 ml. of an aqueous solution of 1% of KSCN, as a gold sensitizer.
• the mixture was then subjected to a second ripening by heating for 60 minutes at 55 C.
• the resulting silver halide emulsion was applied to an undercoated glass plate in a thickness of about microns and dried.
• the light-sensitive glass plate was exposed for second by means of a sensitometer having an intensity scale of 2600 K. and was developed in a developing solution of a D-76 type Metol-hydroquinone developer for 7 minutes at 20 C.
• the results of density measurements of the thus developed plate were as follows: the fog was 0.07; the exposure amount necessary for density 0.1 above fog was 0.12 c.m.s.; and the gamma was 0.91.
• the abovementioned emulsion layer obtained by the process of this invention had a good granularity.
• Experiment Number EXAMPLE 3 Using the compositions shown in Example 1, Solution I was added with stirring to Solution II over a period of 1 minute and the whole amount of the solution mixture of Solution I and Solution II was continuously added with stirring to Solution III over a period of 20 minutes. The second ripening in this case was conducted using the gold sensitizer in an amount six times as much as in Example 1.
• the prepared emulsion corresponding to 10 g. of silver nitrate was mixed with 5 ml. of a methanol solution of 0.1% of 3,3-diethylthia-carbocyanine-iodide, as a color sensitizer, 12 ml.
• a process for the production of a photographic silver halide emulsion which comprises preparing a silver iodide suspension by mixing an aqueous solution containing an iodide and a protective colloid with a solution containing a silver salt in such proportions that the silver iodide suspension contains an excess of silver ions, and adding said silver iodide suspension to an aqueous solution of a bromide, the amount of bromide being in excess of the silver ions, to form an emulsion containing silver iodobromide particles.

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

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Citations (2)

• 1966
  • 1966-09-16 GB GB41435/66A patent/GB1150013A/en not_active Expired
  • 1966-09-16 US US579858A patent/US3482982A/en not_active Expired - Lifetime
  • 1966-09-20 BE BE687144D patent/BE687144A/xx unknown
  • 1966-09-22 DE DE19661547854 patent/DE1547854A1/de active Pending

Patent Citations (2)

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