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
  • G03C8/00—Diffusion transfer processes or agents therefor; Photosensitive materials for such processes
  • G03C8/24—Photosensitive materials characterised by the image-receiving section
  • G03C8/243—Toners for the silver image

Definitions

• This invention in general relates to improved direct positive images produced by the silver salt diffusion process and particularly to compounds which influence the colour of the final silver image in the reception layer.
• R and R represent hydrogen or substituted or unsubstituted alkyl, alkylene, cycle-alkyl or aryl groups.
• the mercaptotriazole grouping appears to be responsible for the efficacy of these compounds.
• the accelerating effect decreases with longer alkyl groups or with aryl radicals.
• R or R are alkyl groups or olefinically unsaturated alkyl groups having up to three carbon atoms, such as methyl, ethyl or allyl.
• the compounds are added in quantities from 1 to 200 mg. per square metre of positive paper and/ or in similar quantities per litre of development solution. Preferred are amounts of 15-50 mg./m. of the reception layer or 15-50 mg./l.
• the compounds according to the invention are readily soluble in aqueous alkaline mediums and can accordingly be added to developer solutions known in the silver salt diffusion process, without it being necessary to modify the constitution of the developer
• the compounds are stable in caustic alkali solution. Their effectiveness is 3,307,944 Patented Mar. 7, 1967 only slightly influenced by the development temperature, but development is preferably carried out at temperatures from 15 to 35 C.
• the mercaptotn'azlole compounds are known per se and are produced, for example, by the processes described in Beilstein, volume 26, pages 142, 143, 174 and in Journal of the Chemical Society (1959), page 3803. They are generally prepared by the method which will now be described for the case of 3-mercapto-4,5-dimethyl-1,2,4- triazole: 105 g. (1 mol) of 4-methylthiosemicarb azide are introduced into 100 ml. of acetic anhydride and stirred for one hour, then another 25 ml. of acetic anhydride are added. The solution is then boiled under reflux for 5 hours and, after cooling, is diluted with 120 ml. of water. The crude product is purified by recrystallisation from water. Yield: 50 g. (40% of the theoretical) of 3-mercapto-4,5-dimethyl-1,2-triazole. Melting point: 214 C.
• Example 1 In a developer of the composition:
• Example 2 A'reception layer is prepared by applying to a paper g./m. which may perhaps also be baryta-coated, a nucleus layer of the following composition:
• nucleus layer is cast a sodium alginate layer by applying a 0.75% aqueous solution of sodium alginate which contains mg. of 3-mercapto-4-phenyl-S-methyl- 1,2,4-tri-azole per litre.
• the layers can contain, in addition, dyestuffs, wetting agents, brightening agents hardeners and other additives.
• a negative paper coated with a high-contrast silver chloride emulsion (1.3 g. of Ag./m. is exposed to form the image of a typewritten document and is. brought in known manner, into contact with the reception layer in the presence of the developer (as in Example 1). seconds after leaving the developing apparatus, the two foils are separated one from another and the same negative is developed another 5 times in the same manner, each time with a new positive paper. For the 5th and 6th copies, the contact time between positive and negative is extended to 15 seconds and 30 seconds respectively. In this way, it is possible to obtain from one negative 6 copies of good legibility with greyish black writing.
• Example 3 A reception layer is obtained by coating a barytacoated paper with the following solution:
• This material is developed and brought into contact in the usual way with a negative exposed to form an image by the reflex rocess.
• a contact time of about 5 seconds after leaving the developing apparatus is suflicient to give a black copy of the original with good density.
• Example 4 A reception layer is prepared by applying the following solution to a support, e.g., paper (60 g./m.
• This positive material is processed, in a high speed developing apparatus in the usual way, with a reflexexposed negative directly after leaving the apparatus and a neutral black copy of the original is obtained which has good legibility.
• Example 5 A solution of Gelatine g 40 Colloidal Ag S g 0.02 Sodium thi'osulphate g 10 3-mercapto-5-methyl-4-ethyl-1,2,4-triazole g 0.06 Formalin (30%) ml 5 Water, 0.8 litre.
• this image-receiving material gives a well-covered and dense transparent copy of the original, which is quite suitable for projection or enlargement.

Landscapes

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

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Citations (2)

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• 0
  • BE BE629344D patent/BE629344A/xx unknown
• 1962
  • 1962-03-10 DE DEA39676A patent/DE1153247B/de active Pending
• 1963
  • 1963-02-20 US US260038A patent/US3307944A/en not_active Expired - Lifetime
  • 1963-02-25 CH CH238263A patent/CH446889A/de unknown
  • 1963-03-08 GB GB9394/63A patent/GB972954A/en not_active Expired

Patent Citations (2)

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