United States Patent (19) 11) 4,267,254 Bloom, Deceased Et Al
Total Page：16
File Type：pdf, Size：1020Kb
United States Patent (19) 11) 4,267,254 Bloom, deceased et al. (45) May 12, 1981 (54) PHOTOGRAPHIC PROCESS Louis et al., Inorganic Nuclear Chem. Letters, vol. 13, (75) Inventors: Stanley M. Bloom, deceased, late of 1977, pp. 31-35. Waban, Mass., by Arlene N. Bloom, Primary Examiner-Richard L. Schilling executrix; Krishna G. Sachdev, Attorney, Agent, or Firm-Gaetano D. Maccarone Cambridge, Mass. 57 ABSTRACT 73) Assignee: Polaroid Corporation, Cambridge, Mass. There is described a photograhic method employing a positive-negative diffusion transfer film unit wherein (21) Appl. No.: 80,349 there is formed a positive silver transfer image which (22 Filed: Oct. 1, 1979 may be viewed as a positive transparency without being separated from the developed negative silver image, (51) Int, Cl. ......................... G03C 5/54; G03C 7/00; including an embodiment wherein additive color pro GO3C 5/38 jection positive images are formed. According to the 52 U.S. Cl. .................................... 430/245; 430/251; method, the exposed film unit is developed by contact 430/428; 430/455 ing the silver halide emulsion layer with a photographic 58) Field of Search ............... 430/245, 246, 251, 428, processing composition which comprises an aqueous 430/455 alkaline solution containing a silver halide developing (56) References Cited agent and a silver complexing agent. The silver com U.S. PATENT DOCUMENTS plexing agent is stable in an alkaline environment, has a melting point less than about 50° C. preferably about 25 3,062,646 1 1/1962 Dann et al........................... 430/600 3,930,867 1/1976 Bigelow ........ ... 430/600 C. or less, and the log of the stability constant (3) for a 3,975,423 8/1976 Borror et al. ... 430/251 1:1 complex of the complexing agent with silver is at 4,017,314 4/1977 Blake ............. ... 430/485 least about 10.5. The film unit is not washed during the 4,168,166 9/1979 Land .................................... 430/245 method. According to the method of the invention crystal formation in the transparency is substantially or OTHER PUBLICATIONS completely eliminated. Pelissard et al., Tetrahedron Letters, vol. 45, 1972, pp. 4589-4592. 15 Claims, No Drawings 4,267,254 1. 2 in the positive silver transfer image is substantially or PHOTOGRAPHIC PROCESS completely eliminated. The present application is drawn to such a method. BACKGROUND OF THE INVENTION This application relates to a photographic diffusion SUMMARY OF THE INVENTION transfer method and, more particularly, to such a It is, therefore, the object of this invention to provide method wherein there are utilized silver complexing a novel photographic diffusion transfer method. agents having advantageous properties. It is another object to provide a method which pro The use of silver complexing agents, also referred to vides positive silver transfer images which may be as "silver halide solvents', in diffusion transfer photo 10 viewed as positive transparencies without being sepa graphic methods is known in the art. In methods of this rated from the developed silver negative image. type an exposed silver halide emulsion is developed by contacting it with a photographic processing composi It is a further object to provide a method for forming tion whereby an imagewise distribution of diffusible additive color positive images which are viewed by image forming components is formed in the unexposed 5 projection upon a viewing surface without being sepa and undeveloped areas of the silver halide. This image rated from the developed negative silver image. wise distribution of image forming components is trans Still another object is to provide a photographic dif ferred to an image receiving stratum which is in super fusion transfer method wherein the film unit is not posed relationship with the silver halide emulsion layer washed during processing. to provide the desired transfer image. 20 It is yet another object of the invention to provide a In diffusion transfer methods wherein a silver transfer diffusion transfer method which utilizes silver complex image is formed, the method is carried out in the pres ing agents having physical properties such that the ence of a silver complexing agent which forms a soluble formation of crystals in the positive silver transfer and diffusible complex with undeveloped silver halide. image is substantially or completely eliminated. The soluble silver complex which is formed diffuses to 25 the superposed image receiving layer where metallic BRIEF SUMMARY OF THE INVENTION silver is deposited to provide the desired silver transfer These and other objects and advantages are accom image. plished in accordance with the invention by providing a Various materials have been taught as being useful as photographic method employing a positive-negative silver complexing agents in positive-negative diffusion 30 diffusion transfer film unit wherein there is formed, transfer photographic methods. Among these are thio without washing, a positive silver transfer image which sulfates, such as potassium and sodium thiosulfate; thio cyanates such as potassium and sodium thiocyanate; may be viewed as a positive transparency without being cyclic amides such as barbituric acid and uracil; 1,1-bis separated from the developed negative silver image. sulfonyl alkanes such as are disclosed in U.S. Pat. No. 35 According to the method, the exposed film unit is de 3,769,014; and alkylthioalkyl-substituted alkylsul veloped by contacting the silver halide emulsion layer fonylacetonitriles such as are disclosed in U.S. Pat. No. with a photographic processing composition which 3,975,423. These materials have been found to be suit comprises an aqueous alkaline solution containing a able for performing their intended functions. Neverthe silver halide developing agent and a silver complexing less, they are not completely satisfactory in every type agent. The silver complexing agent is stable in an alka of positive-negative diffusion transfer film unit wherein line environment, has a melting point of less than about a silver transfer image is formed. 50° C., preferably about 25°C. or less, and the log of the For example, there are known, in the art, diffusion stability constant (3) for a 1:1 complex of the complex transfer methods which are adapted to provide positive ing agent with silver is at least about 10.5. The preferred silver transfer images which may be viewed as positive 45 silver complexing agents are liquids at room tempera transparencies without being separated from the devel ture. oped negative silver image, including methods for form By "stable in alkaline environment' as used in the ing additive color positive images which are viewed by present application is meant that the complexing agent projecting the transparency on a viewing surface. The retains at least 75% of its silver complexing ability after film units employed in such methods are retained intact 50 during processing and are not washed. Accordingly, the being in a IN sodium hydroxide solution for twenty silver complexing agent, which typically may comprise four hours at room temperature. from about 3 to about 15 percent by weight of the pho It has been found that the use of such silver complex tographic processing composition, remains in the image ing agents, because of their physical properties, contrib receiving layer where the silver transfer positive image 55 utes to the substantial or complete elimination of crystal is formed. Because of factors such as the amount of the formation in the transparency. Consequently, such sil silver complexing agent present in the film unit and the ver complexing agents may be used in the amounts physical properties of the known silver complexing typically required to effect rapid and substantially com agents, many of which have relatively high melting plete transfer of the positive silver transfer image form points, the known complexing agents tend to form crys ing components to the image-receiving layer while at tals within a relatively short time, e.g., as brief as a day the same time substantially or completely eliminating after formation of the image. Such crystal formation is the difficulties with crystal formation which have been undesirable because it detracts from the aesthetic qual encountered heretofore. Further, it has been found that ity of the image and in the case of projection transparen silver complexing agents having the specified physical cies adversely affects the quality of the projected image 65 properties may be used in combination with other silver for viewing. complexing agents which do not possess all of the same Thus, it would be desirable to provide a diffusion properties to provide the advantageous results which transfer method of this type wherein crystal formation are obtained according to the method of the invention. 4,267,254 3 4. DESCRIPTION OF THE PREFERRED -continued EMBODIMENTS (III) A positive-negative diffusion transfer film unit which may be utilized in the method of the invention com prises a transparent support such as, for example, an organic polymeric material, carrying a photosensitive silver halide emulsion layer and an image-receiving ( ) S NN layer. In a preferred embodiment the film unit includes CH3 a multicolor additive screen, preferably a three color O screen such as one having alternating red, blue and \ / green lines. These film units can be fabricated by tech (IV) niques which are known in the art. A technique for fabricating a transparent support carrying a pattern of alternating, microscopically fine, red, blue and green 15 ("Ya lines is described in U.S. Pat. No. 3,284,208. Deposition of a silver halide emulsion layer and an image receiving C ) layer can be effected by any of many techniques. The silver halide may be a silver chloride, iodide, bromide, iodobromide, chlorobromide, etc. The binder for the 20 halide, though usually gelatin, may be any suitable poly (V) mer such as polyvinyl alcohol, polyvinyl pyrrolidone and their copolymers.