| 摘要 |
1,071,639. Colloid transfer process. EASTMAN KODAK CO. Oct. 16, 1963 [Oct. 16, 1962], No. 40945/63. Heading G2C. In a multiple colloid transfer process wherein an exposed silver halide emulsion layer is developed with an alkaline solution of tanning developer containing a softening agent for the colloid, e.g. urea and formamide the pH of the alkaline solution is less than that at which the hardening effect of the tanning developer is a maximum and is maintained within a range of 0À1 pH units during the whole transfer process. A non-tanning developer may also be present and the emulsion layer may contain an agent preventing spontaneous hardening e.g. 5, 5-dimethyl cyclohexane-1, 3-dione. The pH control may be obtained by means of a buffering agent e.g. a mixture of potassium carbonate and sodium sesquicarbonate or sodium carbonate and sodium bicarbonate. The alkaline solution may also contain a sequestering agent and an alkaline earth metal or alkali metal chloride. The receiving sheet may contain a fogging agent for silver halide e.g. thiourea and an agent which reduces the rate of tanning by tanning developer e.g. sodium-formaldehyde bisulphite. |
