| 摘要 |
Selecting a surfactant for coatings, especially photographic coatings, comprises minimizing variations in coating thickness caused by temperature variations. Method for selecting a surfactant for coating a substrate comprises: (a) coating the substrate with a composition comprising and aqueous or organic solvent and a surfactant; (b) applying alternating low and high temperatures to successive zones of the coating so that the temperature difference between adjacent zones creates a periodic variation in coating thickness; (c) measuring the thickness for each zone; (d) determining the mean variation in thickness ( DELTA Hm); (e) repeating steps (a)-(d) using a surfactant-free control composition; and (f) selecting a surfactant for which DELTA Hm is less than the control value. Independent claims are also included for: (1) a method for determining the optimum surfactant concentration for coating a substrate, comprising: (a) preparing several compositions comprising an aqueous or organic solvent and a given surfactant concentration; (b) coating a substrate with each of the compositions as described above; and (c) selecting the surfactant concentration giving the lowest DELTA Hm; and (2) apparatus for carrying out the above methods, comprising a coating station, a device for applying the alternating temperatures, and a device for measuring the coating thickness for each zone.
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