techniques for the measurement of beschichtungsmengen, particularly of silicon coating on paper or plastic film.

摘要

Continuous determn. of the amt of coating, esp. silicone coating, on a continuous web of paper, cardboard or plastics film inside a coating plant involves measuring the surface gloss, without contact, before and after coating and using the difference in gloss as a measure of the amt of coating. The gloss is measured by a DIN, ASTM or Tappi standard at a measuring geometry (illumination or observation angle) at 20-85 deg., pref. 60-85 deg. and the measured value is independent of the colour of the substrate and coating. The 2 gloss measurements are made continuously in 2 separate units with separate input and output signals, with on-line measurement traversing, i.e. across the web, so that the gloss can be determined in the lengthwise and crosswise directions. Measurement is carried out directly at the axes of the guide rollers before and after coating, pref. after the coated web has been dried and opt. conditioned and if possible just before the coated web is rolled up. The difference in gloss is measured as decrease or increase in gloss in the lengthwise and crosswise direction and the signal produced by this difference is used for controlling the amt. and uniformity of the coating.