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
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/60—Processes for obtaining vesicular images

Definitions

• the invention relates to a modification of the silver salt diffusion process for the production of photographic images, which consist of a silver image and a vesicle image superimposed on the silver image.
• vesicular images comprises lightscattering photographic materials containing a supported or self-supported layer having photolytic compounds dispersed therein, which upon exposure and development by heat treatment yield minute vesicles acting as light-scattering centers. The unexposed areas of the layer remain transparent. The vesicular image therefore appears dark in transmitted light but light when viewed in reflected light.
• the main disadvantage of vesicular photography is the low light sensitivity of the photographic compounds.
• the particular advantage of this process is the high light sensitivity of the silver halide emulsion layers as compared with the poor light-sensitivity of the known materials used for the production of vesicular images.
• the silver salt diffusion process steps of the process of the present invention are performed in known manner whereby, however, the details of the process steps and measures must, of course, be adapted to the subsequent step, i.e. the production of the vesicle image.
• the light-sensitive silver salt emulsion layer and the image-receiving layer are arranged on separate support.
• the silver salt diffusion process may be carried out under the usual conditions.
• Suitable concentrations are in the region of about 0.1 to 0.3 g. of silver in the form of the silver salt per m.
• concentration of the silver salt solvent must be lower than that normally applied in the silver salt diffusion process. Suitable solvent concentrations for the silver salt content indicated above are, for example, between 1 and 5 g. per 1. of developer in the case of sodium thiosulfate.
• the silver salt emulsion layer may advantageously be washed off before the vesicle image is produced in the image-receiving layer.
• a suitable binding agent for such layers which can be washed off is e.g. unhardened or slightly hardened gelatin.
• An intermediate or separating layer, e.g. of alginates, may be arranged between the silver salt emulsion layer and the image-receiving layer.
• the binding agents and methods of procedure may be selected from those used in known processes.
• the process becomes more complicated when the lightsensitive silver salt layer is arranged on the support and the receiving layer above it.
• one may, for example, first imagewise expose and briefly develop the material and then subject the developed material to ammonia vapour. A weakly covered positive silver image is then obtained in the imagereceiving layer. Vesicle formation may then be effected e.g. by moistening the material with alcoholic hydrogen peroxide solution. Since the silver deposited in the receiving layer has a finer grain than the silver produced in the light-sensitive layer by reduction of the silver halide, it reacts more easily and more rapidly with hydrogen peroxide vapour. Moreover, this vapour first enters the receiving layer, with the result that the vesicles are formed only in this layer.
• Processing may also be carried out by first developing with the usual developers used in the silver salt diffusion process, but these developers should preferably not contain potassium bromide.
• a concentration of silver salt solvent e.g. l to g. of sodium thiosulfate per liter of developer bath.
• the material is exposed to air for some time, which results in the formation of a visible yellow positive image consisting of finely divided silver in the image-receiving layer.
• the superimposed bubble image may then be produced e.g. by treatment with hydrogen peroxide at elevated temperature as will be described hereinafter.
• the optimum conditions for the process such as concentration of active substances, moisture content of the layer temperature conditions, etc. can be determined by simple laboratory tests.
• the receiving layers for the process according to the invention are advantageously layers which contain uniformly distributed development nuclei for the reduction of the transferred silver salt in suitable binders such as proteins, e.g. gelatin, albumin or casein, alginic acid or derivatives thereof, such as salts, esters or amides, starch or starch derivatives, cellulose or cellulose derivatives or synthetic film-forming substances.
• suitable binders such as proteins, e.g. gelatin, albumin or casein, alginic acid or derivatives thereof, such as salts, esters or amides, starch or starch derivatives, cellulose or cellulose derivatives or synthetic film-forming substances.
• suitable nuclei are known from the silver salt diffusion process, e.g. finely divided noble metals, in particular finely divided silver, or heavy metal sulfides or selenides such as silver sulfide and nickel sulfide, etc.
• the concentration of the development nuclei may otherwise vary within wide limits. The optimum concentration depends on the nature of the nuclei and the conditions under which processing is carried out. Quantities of between and 10* g./m. of receiving layer have been found to be suflicient.
• Silver halide emulsion are preferably used as lightsensitive layers. Both silver chloride emulsions and silver bromide emulsions, as well as mixtures thereof which may contain up to about 10 mols percent of silver iodide are suitable.
• the emulsions may contain the silver halide in the form of fine or coarse grams e.g. in the case of ammonia emulsions.
• Suitable binders are e.g. gelatin or other synthetic or natural film-forming substances or mixtures thereof. Materials comprising such emulsion layers are processed in the usual manner.
• the silver image obtained in the image-receiving layer is treated with a compound which is decomposed on the silver image to form gaseous products.
• a compound which is decomposed on the silver image to form gaseous products.
• gases which form oxygen upon decomposition for example hydrogen peroxide (H 0 As to the vesicle forming reaction, we refer to Belgian Pat. No. 725,903 or US. application Ser. No. 748,420, now US. Pat. No. 3,650,755.
• the image-receiving layer which contains the silver image may be covered with a fresh layer containing hydrogen peroxide, e.g. with a solution of polyvinyl chloride in butanone-(2) which contains hydrogen peroxide. After this layer has been applied, the material is dried and the bubbles are produced by heating.
• the image-receiving layer may also be treated with a hydrogen peroxide solution, e.g. an alcoholic solution of hydrogen peroxide.
• the vesicle formation in the image-receiving layer is most advantageously achieved with hydrogen peroxide vapour. After about 30 seconds treatment with saturated hydrogen peroxide vapour, the layer has taken up sulficient hydrogen peroxide.
• the treatment time depends, of course, on the treatment temperature and the concentration of the hydrogen peroxide vapour. Temperatures of 50 to 90 C. for example, are suitable.
• the image-receiving layer which contains the silver image is exposed to an atmosphere of water vapour at about 50 to C. for about half a second to 5 seconds after the treatment with the hydrogen peroxide vapour.
• this treatment with water vapour is carried out, the formation of the minute vesicles which proceeds relatively slowly with hydrogen peroxide treatment alone, then takes place very rapidly.
• the imagereceiving layer, bearing the silver image is exposed to an alkaline water vapour atmosphere after the treatment with hydrogen peroxide.
• pH values of between 8 and 12 are suitable for this alkaline atmosphere. This can easily be achieved by adding small quantities of ammonia or vapours of volatile amines to the water vapour.
• concentration of the alkaline additives is not critical. Quantities of between 0.1 and 5 volumes percent and preferably about 0.3 to 1 volume percent have generally been found sufficient.
• the visible vesicles are formed by expansion of the originally formed gaseous reaction products. This is achieved by heating to temperatures of between 60 and C. Formation of the vesicles is assisted by slightly softening the layer, e.g. by moistening it. This effect is achieved by the treatment with water vapour described above.
• the vesicles are very small. Minute vesicles are particularly advantageous since they form images of high density.
• Light-sensitive photographic materials which contain developer substances in the silver salt emulsion layer or in an auxiliary layer are also suitable for the process of the invention (see Gennran application No". P19-17 744).
• EXAMPLE 1 A silver bromide gelatin emulsion of the following composition is applied to a support of polyethylene terephthalate:
• the silver halide emulsion layer is dried and overcoated by the following image-receiving layer:
• the material is dried.
• the two-layer material contains 0.2 g. of silver in the form of silver halide and about 10* g. of colloidal silver sulfide per m.
• the material is imagewise exposed and developed for one minute in a developer of the following composition:
• the developed layer is then subjected to an ammoniacal atmosphere for 30 seconds, washed for one minute and dried. A very weakly visible positive silver image is obtained.
• Vesicle formation is effected by treating the layer with saturated hydrogen peroxide vapour at 70 C. for half a second.
• a very powerful increase in density immediately occurs due to the formation of minute vesicles, the density in one area of the silver image, for example, being increased from 0.04 to 1.8 in focused light.
• EXAMPLE 2 A casting solution of the following composition is applied to a support of cellulose triacetate to form a layer which contains development nuclei:
• the layer is dried and overcoated by silver halide emulsion of the following composition:
• Example 1 A positive vesicle image of normal covering power having a density of 1.7 (in focused light) is obtained with a silver density of 0.05.
• EXAMPLE 3 A photographic material consisting of a support of cellulose triacetate, a layer containing nuclei and above it a silver chloride gelatin emulsion layer as described in Example 2 is developed in the developer solution of Example 1 but which in addition contains 2 g. of sodium thiosulfate per liter as silver halide solvent. A hardly visible silver image is obtained. The process is then continued as described in Example 2. A positive vesicle image having a density of 1.5 (in focused light) is obtained with a silver density of 0.04.
• EXAMPLE 4 The silver halide gelatin emulsion layer and the imagereceiving layer containing nuclei described in Example 6 2 are each applied separately to separate cellulose triacetate supports.
• the emulsion layer contains 0.2 g. of silver (in the form of silver halide) and the nucleated layer contains about 8.10- of silver selenide per m
• the light-sensitive silver halide emulsion layer is imagewise exposed and developed for 15 seconds in the developer described in Example 2.
• the emulsion layer still soaked with developer solution is then run through a pair of rollers while in contact with the dry imagereceiving layer. After a contact time of 10 seconds, the layers are separated and the image-receiving layer is briefly dried.
• a barely visible positive silver image is found in the image-receiving layer.
• this layer is dipped in 96% aqueous ethyl alcohol containing about 3% of hydrogen peroxide and maintained at a temperature of to C., a positive image having a density of 1.4 (in focused light) composed of the original weak silver image (density 0.04) and minute vesicles is formed after a few seconds.
• a process for the production of photographic images consisting of a silver image and an image superimposed on the silver image composed of visible vesicles, comprising the steps of (a) imagewise exposing a layer of an emulsion containing a silver salt having 0.1 to 0.3 g. of silver per square meter, said layer being on a support;

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=5732474

Family Applications (1)

Country Status (6)

Cited By (2)

Families Citing this family (1)

• 1969
  • 1969-04-26 DE DE19691921361 patent/DE1921361B2/de active Granted
• 1970
  • 1970-04-08 BE BE748627D patent/BE748627A/nl unknown
  • 1970-04-20 CH CH583670A patent/CH527445A/de not_active IP Right Cessation
  • 1970-04-20 US US30343A patent/US3705033A/en not_active Expired - Lifetime
  • 1970-04-22 GB GB09252/70A patent/GB1294598A/en not_active Expired
  • 1970-04-24 FR FR7015128A patent/FR2046506A5/fr not_active Expired

Also Published As

Similar Documents