Improvements in or relating to the manufacture of photographic materials

摘要

A binder free layer of a silver halide is vapour deposited under vacuum by heating a silver halide source to above its decomposition temperature. The deposit is formed on a web of a photographic base material such as baryta paper, an acetate film, "Cronar" or "Mylar" (Registered Trade Marks), to a thickness of 0.1-0.5 microns. Silver bromide is the preferred halide for photographic purposes and the deposition is effected in a conventional vacuum chamber 12 in which the silver halide source is contained in a heated tungsten crucible 32 and the web substrate 29 is continuously moved past aperture 18 by rolls 23 and 24 so that the silver halide evaporated from crucible 32 condenses on the moving web. A shutter 20 operated by hand lever 31 closes aperture 18 until conditions of deposition are stable and in the case of silver bromide the evaporation temperature is 725-765 DEG C. since the bromide decomposes at 700 DEG C. The web should be located about 3 1/2 inches from the crucible so that its temperature is about 50 DEG C. Alternatively the web may be temperature cooled by artificial cooling. Specifications 361,750, 387,967, 802,041 and 968,453 are referred to.