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
  • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
  • G03C1/825—Photosensitive materials characterised by the base or auxiliary layers characterised by antireflection means or visible-light filtering means, e.g. antihalation
  • G03C1/8255—Silver or silver compounds therefor

Definitions

• the present invention relates to colloidal dispersions of silver which are blue in color, and as such, particularly well adapted for use as antihalation layers for color film.
• colloidal dispersions of silverin aqueous gelatin solutions by reduction of silver salts is a well known process.
• colloidal dispersions have been used in photography as antihalation layers or as filter layers for color film, particularly when located between the upper blue sensitive and the intermediate green sensitive layers of multilayer color film.
• colloidal silver filter layers are recommended for absorbing blue light to prevent exposure thereby of the layers sensitized to the longer wave lengths but which also possess an inherent blue sensitivity.
• the colloidal silver is produced, according to this patent, by the reduction of silver nitrate in an alkaline medium in the presence of a peptizing agent by means of such organic reducing agents as dextrin, ferrous citrate or hydroquinone followedby dispersion in gelatin.
• the quantity of silver used is roughly 30 grams of silver nitrate to 1 kilo of emulsion.
• the blue colored dispersions are particularly desirable for forming antihalation layers on color film for the reason that they are more highly efficient in absorbing the longer wave lengths of light to which the layers adjacent the base are sensitive and by which they would be exposed through light reflected from the surface of the base.
• the critical feature of the patent is the employment, in the reduction, of a calcium salt such as calcium acetate or the like, to which is attributed the ability to obtain large particles without the particles precipitating from the gelatin.
• a calcium salt such as calcium acetate or the like
• the calcium salt must be present in a quantity equal to at least about .0017 mole per liter or reaction mixture.
• Tannic acid operates to much greater advantage than the conventional reducing ag'ents such as dextr in, hydroquinone, ferrous citrate and the like, particularly in the presence of the strontium salt. In fact, my results are directly dependent upon the conjoint-use of tannic acid and strontium salts.
• the procedure contemplated herein involves dissolving gelatin in water and adding suflicient alkali to give a pH of above 7.5, preferably between 8 and 9 (Solution 1). Separate solutions are then made up from water, silver (Solution 1) and from water, sodium sulfite and tannic acid (Solution III).
• Solution II is added to Solution I and after a pause of 2 to 5,:Solution III is dumped inwith vigorous agitation, preferably while using several stirrers.
• the emulsion is digested at 40 C., for about 20 minutes, chilled, shredded and Washed. Alternatively, the dispersion may be coagulated, washed, remelted and chilled.
• the quantities of the various essential components may vary so long as there is present, the aforesaid minimum of strontium nitrate and an adequate quantity of silver salt and reducing agent to yield the dense blue colored dispersion.
• I may employ .2 to .4 kilo of silver nitrate, .015 to .10 kilo of strontium nitrate, .1 to .4 kilo of sodium sulfite and .2 to .4 kilo of tannic acid.
• the proportions of the ingredients used in the above patent US. 2,688,601 are adequate.
• the resulting dispersion is coated on a film support in the usual manner and dried to produce a very effective bluev colored antihalation layer- When coated at a concentration of 3.2 milligrams of silver per 100 square centimeters, the optical density is 0.15 at 450 my and 2.35 at 650 ma. 7
• I claim; 7 -1 A method ofpreparing a blue color dispersion of silver in gelatin comprising admixing an aqueous alkaline gelatin solution with a water soluble silver salt and at least about .005 mol'of a water soluble strontium salt per liter of the reaction mixture, and eflecting reduction of the silver salt by adding an amount of an alkali metal sulfite which is at least one half of the weight of the silver salt and an excess of tannic acid.
• a stable dispersion of silver in gelatin said dispersion having a dense 'blue color and being particularly adapted for use as an anti-halation layer for a multilayer color film, said dispersion being prepared according to the procedure of, claim 1.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Colloid Chemistry (AREA)
• Heterocyclic Carbon Compounds Containing A Hetero Ring Having Nitrogen And Oxygen As The Only Ring Hetero Atoms (AREA)
• Pyridine Compounds (AREA)

Priority Applications (4)

Applications Claiming Priority (1)

Publications (1)

Family

ID=24565873

Family Applications (1)

Country Status (4)

Cited By (4)

Citations (1)

• 0
  • BE BE562967D patent/BE562967A/xx unknown
• 1957
  • 1957-02-13 US US639863A patent/US2921914A/en not_active Expired - Lifetime
• 1958
  • 1958-01-10 DE DEG23698A patent/DE1075942B/de active Pending
  • 1958-01-27 GB GB2714/58A patent/GB843713A/en not_active Expired

Patent Citations (1)

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