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
  • G03C1/77—Photosensitive materials characterised by the base or auxiliary layers the base being of metal

Definitions

• U.S. Pat. No. 2,766, 19 defines the prior art and indicates the difficulties experienced by earlier workers in the field. These difficulties resided primarily in the inability to obtain a plate which exhibited any significant shelf life. As a consequence, it was required that the plate be sensitized immediately prior to the exposure. U.S. Pat. No. 2,766,! 19 describes a way to improve the shelf life by adding an organic hydrocolloid in one of the impregnating steps. As a consequence, the shelf life of the finished article was extended to several years. Recent experience has established that the shelf life of such a plate is at least years. However, through the fundamental problem of lack of storageability has been eliminated by the teachings of US. Pat.
• the pores are then impregnated with a water solution of a soluble silver salt which contains a minor amount of gelatin (in accordance with the teachings of U.S. Pat. No. 2,766,119) and after drying from the first impregnation solution, the silver salt is transformed to a halide, generally comprising a mixture of chloride-bromide-iodide or a mixture of bromide and iodide, through treatment of the previously silver salt impregnated base with an appropriate solution of an alkali halide. Normally, in order to ensure that no bare aluminum is exposed, the alkali halide solution also contains a small amount of oxidizing agent.
• the organic portions of this solvent suitable for the purposes of the invention are listed in table 1.
• Each of these solvents is highly polar in character, completely miscible with water, and that most alkali halides exhibit limited solubility in such solvents.
• the solvent for the silver salt to be deposited in the pores of the anodized surface normally contains a minor amount of water, usually between 10 and 30 percent, in order to achieve the desired degree of solubility of the silver nitrate in such a solvent.
• the amount of water used is generally not sufiicient to have a major effect on the eventual solubility of the alkali halide.
• the balance of the solvent comprises one of the organic solvents listed'in table 1 or mixtures thereof.
• Silver nitrate concentrations useful for achieving the desired end results range between 6 grams by weight of silver nitrate to 20 grams by weight of silver nitrate per hundred cc. of solvent and the optimum range for the best results is between l2 grams of silver nitrate and 15 grams of silver nitrate per hundred cc. of solvent.
• the minimum time of immersion in this solution to achieve the desired results is approximately 30 seconds for plates anodized in the preferred manner and better results are obtained by extending the time of immersion from 1 minute up to a maximum of5 minutes.
• electrolytic oxidation or, as it is generally designated commercially, anodizing.
• aluminum may be anodized in an electrolyte make up of a mixture of oxalic acid and oxalates of alkali metals, at a pH of l to 5, a current density covering a range between 0.5 and amperes per square decimeter, and a temperature range between 40 and 75 C. Direct current anodizing is preferred.
• Anodized surfaces made in this way are hard, adherent and are highly absorbent for soaking up liquids and salts in solution.
• Anodizing under the conditions just described is generally continued for a time period sufficient to yield a thickness of the anodized layer of at least the order of 0.0002 inches and preferably up to a thickness of 0.005 inches. Under these conditions, the
• time of anodizing is generally about 30 minutes.
• the aluminum surface After the aluminum surface has been initiallyoxidized, it is then subjected to a chemical treatment involving powerful oxidation which makes certain that no metallic aluminum is exposed at the base of the pores.
• Useful energetic oxidizing agents for this purpose include chromic acid, solutions of alkali ferricyanides, dichromates, or chromates in concentration ranges of 0.01 to 10 percent.
• the plate bearing the prepared oxidized aluminum surface is then dipped into the solutions which eventually produce the photosensitive salts of silver in the pores of the coating and not on the surface.
• Small amounts of oxidizing agents may be added during the photosensitive impregnation process to insure complete protection against undesired exposure of metallic aluminum, such exposure showing a spot defeet in finished plates which is not acceptable commercially.
• both the silver nitrate solutions and the alkali halide solutions may contain small amounts of water-soluble oxidizing agents of the types just described for continued insurance against the presence of bare spots of aluminum.
• a preferred slat of silver for achieving the desired result is silver nitrate and the preferred alkali halides are the sodium or potassium chlorides, bromides, or iodides.
• a preferred procedure is to apply the silver nitrate in solution, then a solution of an alkali chloride, and after the silver chloride has been formed in the oxide coating, the plate may be ripened in an alkali bromide or alkali iodide or combinations of the bromide and iodide.
• the amount of oxidizing agents used in combination with the soluble silver salt is very small, on the order of 0.01 to 0.03 percent of an alkali metal ferricyanide', dichromate, or chromate, as described in the above noted U.S. Pat. No. 2,766,119.
• the potassium bromide or chloride are preferred, but other alkali halides can be used.
• sodium chloride is preferred because of its highly limited solubility in the organic solvents listed in table 1.
• the alkali halide solutions utilized have concentrations in the range 'of to percent.
• the plates After formation of the silver halide salts in the pores, the plates are washed and dried and are then ready for use.
• the photographic plate thus obtained is exposed to a pattern of light, developed and fixed in accordance with usual photographic practices, e.g. as described in the above noted U.S. Pat.
• the image may be toned with salts or the background dyed to achieve spacial effects in accordance with known practice and a final operation which is usually advisable is to seal the surface so that it is permanently resistant to abrasion and scratching.
• This consists of immersing the plate in boiling solutions 'of salts, such as sodium sulfate, sodium acetate, and the like for a period of about l0 minutes.
• the surface may also be sealed and waterproofed by the application of silicone polishes or various synthetic resins which may be cured on the surface.
• EXAMPLE Z The dried preoxidized plate as prepared in example 1 was used as a base in the darkroom, 6 grams of silver nitrate were dissolved in a mixture of 80 cc. of isopropyl alcohol and 20 cc. of distilled water. In addition, 0.02 grams of potassium dichromate were also added to the solution and stirred until solution was complete. The dried anodized plate was soaked in this solution for 5 minutes, allowed to drain and the excess solution wiped from the surface with a rubber squeegee. Without intervening drying, the plate was then soaked for 1 minute in a solution containing 20 grams of sodium chloride and 3 grams of potassium dichromate in 100 cc. of distilled water. The surface was again squeegeed to remove any precipitate that might have developed on this surface and then the plate was washed in running water. The thoroughly washed plate was then oven dried at 50 and stored in the dark until used.
• EXAMPLE 3 The same as example 2, except that 15 grams of silver nitrate were dissolved in 100 cc. of a mixture of 25 cc. of water and 75 cc. of isopropyl alcohol. In this case, the first impregnation was permitted to continue for 1 minute before squeegeeing and following with the treatment with the sodium chloride solution.
• EXAMPLE 4 The same as example 2, except that after washing after the sodium chloride treatment step, the plate was placed in a bath containing 12 k grams of potassium ferricyanide, 10 grams of potassium bromide and 2 grams of sodium dichromate, all dissolved in a liter of water, and retained in this bath for l TABLE 2.SAl ⁇ lE AS, EXAMPLE 5, EXCEPT FOR CHANGES minute. After rinsing with running water, the wet plate was then immersed in a 1 percent solution of potassium bromide for 1 minute and was then washed thoroughly, dried at 50 C., and stored in the darkroom until used.
• EXAMPLE 5 The same as example 4, except that in place of the 1 percent potassium bromide solution, the solution used consisted of a mixture of 1 percent potassium bromide and l percent potassium iodide dissolved in distilled water.
• EXAMPLE 6 The same procedure'as described in example 3, except that the 1 percent potassium bromide bath used for ripening contained 0.01 percent of silver nitrate.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Printing Plates And Materials Therefor (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=21881587

Family Applications (1)

Country Status (5)

Cited By (6)

• 1970
  • 1970-05-06 US US35262A patent/US3615553A/en not_active Expired - Lifetime
• 1971
  • 1971-05-05 CA CA112281A patent/CA936405A/en not_active Expired
  • 1971-05-06 GB GB1356071*[A patent/GB1309227A/en not_active Expired
  • 1971-05-06 DE DE19712122430 patent/DE2122430A1/de active Pending
  • 1971-05-06 JP JP2951471A patent/JPS5332251B1/ja active Pending

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