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
  • G03C1/04—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with macromolecular additives; with layer-forming substances
  • G03C1/053—Polymers obtained by reactions involving only carbon-to-carbon unsaturated bonds, e.g. vinyl polymers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/136—Coating process making radiation sensitive element

Definitions

• Patented May 2; recs roLYvrNYi. onoL EMULSlON cosrrnvd Wesley G. howe and Kearney 1. Grlilln, Roche ester, N. Y1, assignors to Eastman Kodak Company, Rochester, N. Jersey No Drawing.
• This invention involves a method of preparing photographic products from polyvinyl alcohol sliver halide emulsions.
• One object of our invention is to provide a method for the rapid setting of polyvinyl alcohol emulsion layers so that photographic products may be easily manufactured therefrom with the use of only a reasonable amount of time for that merits a rapid setting of the emulsion layer is obtained resulting in uniformity and ease of preparation of the photographic product.
• the emulsion may be read- 5 ily coated out upon a support such as. paper or iilm base to form a thin layer which is quickly set by fuming with ammonia or the like.
• Another object of our invention is to provide a method for preparing photographic products from polyvinyl alcohol emulsions in which the emulsion may be coated out at ordinary temperature.
• a further object of our invention is to provide a method forsetting polyw vinyl alcohol photographic emulsions which method is not affected by the presence oi gelatin in the emulsion.
• Many of the jelling agents previously proposed lose their effectiveness when photographic emulsion as undesirable because it is known to increase the graininess and speed of emulsions and to raise their pH.
• boron compounds have been. found to be' suitable.
• borer, sodium borate, boric acid, or the like may be employed providing it is mixed with the polyvinyl alcohol emulsionunder acid conditions.
• emulsion should never beallowed to exceed 7 and it is preferably kept at a pH of not-more than ii.
• a still further object of our invention is to provide a method for costing out polyvinyl alcohol emulsions in which low viscosity polyvinyl alcohols have been employed in their preparation. Due to the nature of our invention, low viscosity or greatly diluted polyvinyl alcohol solutions can be employed without.
• boric acid may be employed, it is known that larger proportions of boron compounds exert marked effects on the viscosity of polyvinyl alcohol and too great a proportion of boron compound does increase the difficulties in the coating operations. Where, however, this is not objectionable, such as where the emulsion is warmed immediately prior to applying as an emulsion layer, there is no objection to the use of larger.
• Our method of setting photographic emulsion layers makes possible the use of very low viscosity polyvinyl alcohols as the carrier for silver halides.
• Our invention makes possible more dilution of polyvinyl alcohol photographic emulsions than has been considered safe previously to assure a uniform and substantially even coating.
• a very convenient way to prepare photographic products in accordance with our invention is to first treat the polyvinyl alcohol emulsion with a gelling agent so as to gel the same at a low temperature thereby enabling the operator to cut the emulsion into shreds and wash the same. Thereupon the shreds are washed with cold water to remove everything but the silver halide and the carrier therefor. The washed emulsion may then be worked up and employed by coating it out on photographic film or photographic paper. For instance, a good photographic paper may be prepared by taking an ordinary baryta coated paper,
• Example 1 An emulsion of silver halide-polyvinyl alcohol was prepared containing a-naphthol therein in accordance with the directions given in U. S. Patent 2,311,058. The emulsion was set by gelling, shredded and washed in accordance with the description of that patent. The emulsion was then warmed to liquefy it, the pH was adjusted to 5 and 100 cc. thereof was mixed with 2 cc. of
• Example 2 A portion of the emulsion of Example 1 containing acidified borax was diluted with 5 its weight of water. This lowered its viscosity and made coating easier. The emulsion was then coated out on a glass plate and fumed with ammonia as before. The emulsion set very rapidly and the resulting product gave good sensitometric results.
• Example 3 Some of the emulsion, as prepared in Example 1, was coated onto a cellulose acetate film base which was then passed through a chamber filled with ammonia gas. Very rapid setting occurred and the film was readily dried in a stream of air in the usual way. In this case the thickness of the coating was of the order used on commercial photographic film. Examination of the developed image obtained with the film showed that it was not higher in graininess than the developed image from the same emulsion not fumed with ammonia. The photographic speeds were also equal whether or not ammonia was used to set the emulsion.
• Example 4 A silver halide emulsion .was prepared by first preparing the silver halide in a solution containing gelatin as the silver halide dispersing agent followed by the addition of polyvinyl alcohol to silver halide as described in U. s, Patent No. 2,276,323 of Wesley G. Lowe. The ratio of gelatin to polyvinyl alcohol in the emulsion was about one to ten. cc. of the emulsion was taken and its pH was adjusted to 5.5 by the addition of acetic acid. 2 cc. of 4% acid boric solution (pH 6) was added thereto and the emulsion was coated on film base. Fuming with ammonia gave rapid setting and the dried and processed film showed no increase in graininess due to the action of the ammonia.
• Example 5 A silver halide emulsion was prepared by preparing the silver halide as in the preceding exampreceding example and in the same quantity. The emulsion was coated onto film base and fumed with ammonia. It was found that rapid setting occurred and that the film dried and could be processed in the usual manner.
• Our invention is directed to a process of setting photographic emulsion coatings, and admits of reversing the setting characteristics if, for any reason, the operator desires to again liquefy the emulsion.
• the emulsion may be recovered by treatment with, aqueous acid such as by soaking the photographic product in a dilute solution of acetic acid for a time. After recovering the emulsion from its support in liquid form, it may be further treated and again coated out on a support such as a glass plate, photographic paper or film base and fumed with a volatile base to again cause setting.
• a method of preparing photographic products from polyvinyl alcohol-silver halide emulsions which comprises incorporating a small proportion of boric acid in the emulsion at a pH of not more than 6, coating out the emulsion upon a support, fuming with a volatile base to set the emulsion, coating and drying the same, all under conditions whereby the light sensitiveness of the emulsion is not detrimentally affected.
• a method of preparing photographic products which comprises incorporating in a polyvinyl alcohol photographic emulsion a small amount of a gelling agent and gelling the emulsion at low temperature, cutting the emulsion into shreds and washing the same, incorporating in the emulsion a small proportion of an aqueous solution of borax having a pH of 6 imparted thereto by acetic acid, coating out the emulsion upon a support, fuming with a volatile base to set the emulsion coating and then drying the same all under conditions whereby the lightsensitiveness of the emulsion is not detrimentally affected.
• a method of preparing photographic products from polyvinyl alcohol-silver halide emulsions which comprises incorporating a small proportion of a boron compound which forms boric acid under aqueous acid conditions, in the emulsion at a pH of not more than 6, coating out the emulsion upon a support, fuming the emulsion coating with a volatile base to set the same, and then drying the emulsion coating, all under conditions whereby the light-sensitiveness of the emulsion is not detrimentally affected.
• a method of preparing photographic products which comprises incorporating into a silver halide-polyvinyl alcohol photographic emulsion in aqueous form a small proportion of a boron compound which forms boric acid under aqueous acid conditions, at a pH of not more than 6, coating out the emulsion upon a support therefor, setting the emulsion coating by subjecting to the action of ammonia gas, and drying the emulsion coating upon the support, all under conditions whereby the light sensitiveness of the emulsion is not detrimentally affected.
• a method of preparing photographic products from polyvinyl alcohol-silver halide emulsions which comprises incorporating therein a small proportion of a boron compound, which forms boric acid under aqueous acid conditions, at a pH of not more than 6, coating out the emulsion upon paper, setting the emulsion by fuming with a volatile base, and then drying the same, all under conditions whereby the light-sensitiveness of the emulsion is not detrimentally affected.
• a method of preparing photographic products from polyvinyl alcohol-silver halide emulsions which comprises incorporating a small proportion of borax in the emulsion at a pH of? not more than 6, coating out the emulsion upon a support, fuming the emulsion coating with a volatile base to set the same and then drying the emulsion coating, all under conditions whereby the light-sensitiveness of the emulsion is not detrimentally affected.
• a method of preparing ucts from polyvinyl alcohol-silver halide emulsions which comprises incorporating in the emulsion a small proportion of borax having a pH of 6 imparted thereto by acetic acid, coating out the emulsion upon a support, fuming the emulsion coating with a volatile base to set the same and then drying the emulsion coating, all under conditions whereby the light-sensitiveness of the emulsion is not detrimentally affected.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Colloid Chemistry (AREA)

Priority Applications (2)

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

Country Status (2)

Cited By (17)

• 0
  • FR FR961819D patent/FR961819A/fr not_active Expired
• 1943
  • 1943-09-11 US US501990A patent/US2376371A/en not_active Expired - Lifetime

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