Process for predicting degree of mottling in coating compositions by wet color measurement

摘要

The process includes measuring flops of a layer of the coating composition applied over a test substrate of a mottling prediction device of the present invention at the start and then after a desired time interval. A delta flop is determined by subtracting from the flop at the start from that after the desired time interval and a degree of mottling of a coating resulting from the layer is visually assessed. The process is repeated with varying amounts of one or more rheology additives added to the composition and the degree of mottling vs. delta flop is plotted on a graph and then by using a curve fitting equation, a mottling prediction curve is obtained. By measuring the delta flop of a wet layer of a target coating composition, the degree of mottling in the target coating composition can then be predicted by using the mottling prediction curve.

主权项

1. A process for predicting degree of mottling in a target coating composition comprising:
(a) adding to a vessel of a mottle prediction device a S0 coating composition; (b) dispensing from an opening in said vessel said S0 coating composition over a test substrate to produce a L0 layer of a substantially uniform thickness thereon; (c) projecting on said L0 layer a beam of light of a preset intensity at preset angles of incidence from a light source; (d) measuring B0 flop of said beam reflected from said L0 layer at preset angles of reflectance by an optical measurement instrument; (e) measuring BH0 flop of said beam reflected from said L0 layer at preset angles of reflectance by said optical measurement instrument after a desired time interval; (f) producing a C0 coating from said S0 coating composition; (g) assessing a degree of mottling Y0 of said C0 coating; (h) repeating said steps (a) through (g) for S1 to Sn coating compositions respectively comprising F1 to Fn parts by weight of one or more rheology additives based on 100 parts by weight of said S1 to Sn coating compositions to determine B1 to Bn flops and BH1 to BHn flops of L1 to Ln layers after said desired time interval, respectively, and degree of mottling Y1 to Yn of C1 to Cn coatings, respectively wherein n ranges from 1 to 100; (i) subtracting said BH0 to BHn flops from said B0 to Bn flops of said L0 to Ln layers, respectively to determine ΔB0 to ΔBn flops; (j) storing said B0 to Bn flops, said BH0 to BHn flops, said ΔB0 to ΔBn flops and said degree of mottling Y0 to Yn in a non-transitory computer usable storage medium of a computer; (k) locating intersecting points on a graph where said ΔB0 to ΔBn flops of said L0 to Ln layers on X-axis of said graph intersect with said degree of mottling Y0 to Yn on Y-axis of said graph; (l) using a curve fitting equation to produce a degree of mottling prediction curve on said graph; (m) dispensing on said test substrate a LT layer of said substantially uniform thickness of a target coating composition from said vessel wherein said target coating composition contains flakes; (n) projecting on said LT layer a beam of light at said preset intensity and at said preset angles of incidence from said light source; (o) measuring BT flop of said beam reflected from said LT layer at said preset angles of reflectance by said optical measurement instrument; (p) measuring BHT flop of said beam reflected from said LT layer at preset angles of reflectance by said optical measurement instrument after said desired time interval; (q) subtracting said BHT flop from said BT flop of said LT layer to determine ΔBT flop; (r) locating said ΔBT flop of said LT layer on said X-axis of said graph; (s) locating an intersecting point on said degree of mottling prediction curve that intersects with said ΔBT flop on said X-axis of said graph; and (t) predicting degree of mottling of said target composition by locating YT on said Y-axis of said graph that intersects with said intersecting point on said degree of mottling prediction curve that intersects with said ΔBT on said X-axis of said graph.