Patent ID: 6177128
Filing Date: 2001-01-23
Classification: G03C

Abstract:
The method of coating by bead coating or curtain coating at speeds exceeding 300 feet per minute a plurality of photographic coating compositions comprising aqueous gelatin on a receiving surface in a coating environment comprising specified temperature and humidity comprising the steps of:(a) providing said receiving surface with a roughness R.sub.z less than about 3 microns:(b) obtaining a sample of said receiving surface;(c) measuring the rotating disk coater index value (RDC index value) of said sample by;1. providing a test liquid comprising aqueous gelatin;2. providing a test receiving surface;3. providing a test environment of temperature and humidity corresponding to said coating environment;4. spacing a nozzle from said test receiving surface in said test environment by a distance of at least 1 mm but not exceeding a distance of three times the maximum dimension of said nozzle;5. flowing said test liquid out said nozzle at a flow rate sufficient to form a ribbon of test liquid between said nozzle and said test receiving surface;6. rotating said test receiving surface at constant angular velocity about a center initially spaced from said nozzle such that the speed of said test receiving surface with respect to said nozzle is high enough that air entrainment is observed;7. translating said nozzle radially inward, the speed of said test receiving surface with respect to said nozzle thereby decreasing; and recording the radial position of said nozzle when air entrainment is observed to cease;8. computing a test speed value at which air entrainment is observed to cease from said recorded radial position and said constant angular velocity;9. providing a reference receiving surface of polyethylene terephthalate at a relative humidity of 50% at 21.degree. C.;10. repeating steps (c) 1 through 8 with said reference receiving surface;11. dividing said test speed value for said sample of said receiving surface by said test speed value for said reference receiving surface to obtain said RDC index value;(d) determining if said RDC index value for said receiving surface is less than about 0.5;(e) if said RDC index value of said receiving surface is less than about 0.5, obtaining an altered receiving surface by altering its chemical composition or by altering said test environment and measuring said RDC index value of said altered receiving surface, one or multiple times, until said RDC index value of said altered receiving surface exceeds about 0.5;(f) altering said coating environment to correspond to said altered test environment; and(g) coating without air entrainment said photographic coating compositions onto said receiving surface of (e) in said coating environment of (e) at a speed exceeding 300 feet per minute by said curtain coating or bead coating method.