Patent Publication Number: US-2009233245-A1

Title: Color Film Developer Composition and Process Therefor

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to film development processes and, more particularly to color film development processes and developers therefor. 
     2. Description of the Background Art 
     Images captured in printed pictures or on film are used to communicate information and ideas. Color film based images are typically produced by irradiating a silver halide-based emulsion thereon to produce a latent image in the silver halide grains of the emulsion. The exposed color film may then be conventionally developed using a wet chemical developing process. 
     Conventional wet chemical developing processes generally utilize a series of tanks containing various processing solutions. The undeveloped exposed color film is fully immersed into each of the tanks containing the various processing solutions. A typical wet chemical developing process includes a single development step in which the exposed film is immersed in individual tanks for developing, fixing, bleaching and drying, as well as various rinsing operations. Such conventional wet chemical developing processes remove a portion of the silver and silver halide from the emulsion to produce a color dye image on the film. 
     For some wet chemical developing processes, it is important to increase the silver retention of the processed color film in order to achieve a unique look, such as, for example, cleaner highlights, blacker blacks and desaturated color. Challenges to wet chemical development processes when increasing the silver retention of the color film are that the highlights can be muddy and color timing may be difficult to achieve. 
     Thus, it would be desirable to increase silver retention on processed color film. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a method and composition for processing color film. The color film is processed by developing it using first and second compositions. The second composition is an aqueous composition including a buffer, an antioxidant, a preservative, a hydroxide and a developer selected from the group consisting of a hydroquinone and an ascorbic acid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       The invention will now be described in greater detail, with relation to the accompanying drawings, in which 
         FIG. 1  is a schematic diagram illustrating a wet chemical development process of the present invention; and 
         FIG. 2  is a flow diagram illustrating the process steps used for the wet chemical development process detailed in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION  
       FIG. 1  is a schematic illustration for a conventional wet chemical development process for color film. As shown in  FIG. 1 , color film  10  is fed via rollers  15  into various tanks during the development process including a first development tank  20 , a stop tank  25 , a first wash tank  30 , a first fixer tank  35 , a second wash tank  40 , a bleach accelerator tank  45 , a persulfate bleach tank  50 , a third wash tank  55 , a sound track applicator tank  60 , a fourth wash tank  63 , a second developer tank  65 , a second fixer tank  70 , a second fixer wash tank  75  and a final rinse tank  80 . The color film  10  travels through the various tanks during the development process at a speed between about 400 fpm (feet per minute to about 1000 fpm. 
     The color film  10  is developed according to the process steps shown in the flow chart of  FIG. 2 . Initially, the color film  10  is immersed in a first developer tank  20 , as indicated by reference numeral  120 . The first developer tank  20  includes an industry standard color film developing solution which transforms the latent image exposed on the film into a visible image when the color film is immersed therein. The first developing solution develops the exposed silver halide in the color film and reacts with color coupling agents in the film to create dye layers along with a silver image. 
     Time and temperature control are especially important for optimum image quality. The conditions (e.g., time of development, temperature of the developer solution, etc.) may vary according to industry standards. For example, the developer solution is typically held at a temperature of about 90° C. The color film  10  may travel through the first developer tank  20  during the development process at a speed between about 400 fpm (feet per minute to about 1000 fpm. 
     As indicated by reference numeral  125  in  FIG. 2 , after the film is developed in the first developer tank  20 , it is immersed in a stop tank  25 . The stop tank  25  includes a stop bath typically comprising a dilute acid solution which stops the development in the color film and removes the developer solution from the film surface. For example, the stop bath may be a dilute solution of acetic acid. 
     After the color film  10  is immersed in the stop tank  25  it is washed in the first wash tank  30 , indicated by reference numeral  130 . The first wash tank  30  uses water to remove the dilute acid stop bath from the color film surface. 
     The color film  10  is next immersed in a first fixer tank  35 , as indicated by reference numeral  135 . The first fixer comprises an industry standard fixer solution which makes the visible image in the developed film permanent and light insensitive. 
     As indicated by reference numeral  140  in  FIG. 2 , after the film is fixed in the first fixer tank  35 , it is immersed in a second wash tank  40 . The second wash tank  40  uses water to remove the fixer solution from the color film surface. 
     After the color film  10  is immersed in the second wash tank  40  it is provided to a bleach accelerator tank  45 , indicated by reference numeral  145 . The bleach accelerator tank  45  includes an industry standard bleach accelerator solution. 
     The color film  10  is next immersed in a persulfate bleach tank  50 , as indicated by reference numeral  150 . The persulfate bleach tank  50  includes an industry standard persulfate bleach solution which converts the visible image formed by the developer solution into silver halide. 
     As indicated by reference numeral  155  in  FIG. 2 , after the film is bleached in the persulfate bleach tank  50  it is immersed in a third wash tank  55 . The third wash tank  55  uses water to remove the persulfate bleach solution from the color film surface. 
     After the color film  10  is immersed in the third wash tank  55 , it is provided to a sound track applicator tank  60 , indicated by reference numeral  160 . The sound track applicator tank  60  includes an industry standard sound track developer solution to develop the sound track in the color film. 
     As indicated by reference numeral  163  in  FIG. 2 , after the film is developed in the sound track applicator tank  60 , it is immersed in a fourth wash tank  63 . The fourth wash tank  63  uses water to remove the sound track developer solution from the color film surface. 
     After the color film  10  is immersed in the fourth wash tank  63  it is provided to a second developer tank  65 , indicated by reference numeral  165 . The second developer tank  65  includes second developer solution of an aqueous composition including a buffer, an antioxidant, a preservative, a hydroxide and a developer selected from the group consisting of a hydroquinone and an ascorbic acid. 
     The second developer solution increases silver retention on the processed color film to achieve cleaner highlights, blacker blacks and desaturated color. In order to achieve the cleaner highlights, blacker blacks and desaturated color this second development of the color film is performed after the sound track development step and before a subsequent second fixing step (discussed below). 
     The second developer solution should include hydroquinone within a range of about 3.5% weight/volume to about 5.5% weight/volume. Alternatively, the second developer solution should include the ascorbic acid within a range of about 3.5% weight/volume to about 5.5% weight/volume. 
     The buffer may be a carbonate, such as sodium carbonate. Other suitable carbonates may include, for example potassium carbonate and ammonium carbonate. The second developer solution should include carbonate within a range of about 1.5% weight/volume to about 2.5% weight/volume. 
     The antioxidant and preservative may comprise the same material, such as, for example sodium sulfite. Other suitable examples may include potassium sulfite and ammonium sulfite. The second developer solution should include the antioxidant and preservative within a range of about 2% weight/volume to about 4% weight/volume. 
     The hydroxide is used to adjust the pH of the aqueous composition and may be sodium hydroxide. Other suitable examples may include potassium hydroxide and ammonium hydroxide. The second developer solution should include the hydroxide within a range of about 1.5% weight/volume to about 2% weight/volume. 
     In one exemplary wet chemical color film development process, a 1 liter second developer solution is made by adding to 800 ml of water at about 90° C., 20-40 grams of sodium sulfite, 35-55 grams of hydroquinone, 15-25 grams of sodium carbonate and 18 grams of sodium hydroxide (for pH adjustment). Water is then added to bring the composition to 1 liter and additional sodium hydroxide added to correct the pH to 10.90±0.10. Deionized water may be used to make the second developer solution, although deionized water is not required. 
     In another exemplary wet chemical color film development process, a 1 liter second developer solution is made by adding to 800 ml of water at about 90° C., 20-40 grams of sodium sulfite, 40-65 grams of ascorbic acid, 15-25 grams of sodium carbonate and 18 grams of sodium hydroxide (for pH adjustment). Water is then added to bring the composition to 1 liter and additional sodium hydroxide added to correct the pH to 10.90±0.10. Deionized water may again be used to make the second developer solution, although deionized water is not required. 
     As indicated by reference numeral  167  in  FIG. 2 , after the film is developed in the second developer tank  65 , it is immersed in a fifth wash tank (not shown in  FIG. 1 ). The fifth wash tank uses water to remove the second developer solution from the color film surface. 
     After the color film  10  is immersed in the fifth developer tank, it then provided to a second fixer tank  70 , as indicated by reference numeral  170 . The second fixer tank  70  comprises an industry standard fixer solution which removes the silver halide formed during bleaching from the color film. 
     As indicated by reference numeral  175  in  FIG. 2 , after the film is fixed in the second fixer tank  70  it is immersed in a second fixer wash tank  75 . The second fixer wash tank  75  uses water to remove the second fixer solution from the color film surface. 
     After the color film  10  is immersed in the second fixer wash tank  75 , it then immersed in a final rinse tank  80 , as indicated by reference numeral  180 . The final rinse tank  80  includes an industry standard final rinse solution to aid in the subsequent drying of the color film. 
     As indicated by reference numeral  185  in  FIG. 2 , after the film is finally rinsed in the final rinse tank  80 , it is dried in a drybox  85 . In the drybox  85 , the film is dried using standard drying temperatures. Thereafter the dried film is wound on spools for subsequent projection or printing. 
     During the exemplary wet chemical development process described above, the second developer solution may become depleted. When the second developer composition becomes depleted, a replenisher solution may be added thereto. 
     In one exemplary wet chemical color film development process, a 1 liter second developer replenisher solution is made by adding to 800 ml of water at about 90° C., 30 grams of sodium sulfite, 55 grams of hydroquinone, 20 grams of sodium carbonate and 18 grams of sodium hydroxide (for pH adjustment). Water is then added to bring the composition to 1 liter and additional sodium hydroxide added to correct the pH to 10.90±0.10. Deionized water may be used to make the second developer replenisher solution, although deionized water is not required. 
     Although an exemplary method and composition for processing color film using a second developer which incorporates the teachings of the present invention has been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings.