SURFACE ELASTIC EFFECTS IN PREMETERED COATING TECHNIQUES

Citation
Je. Valentini et al., SURFACE ELASTIC EFFECTS IN PREMETERED COATING TECHNIQUES, Industrial & engineering chemistry research, 35(2), 1996, pp. 434-449
Citations number
45
Categorie Soggetti
Engineering, Chemical
ISSN journal
08885885
Volume
35
Issue
2
Year of publication
1996
Pages
434 - 449
Database
ISI
SICI code
0888-5885(1996)35:2<434:SEEIPC>2.0.ZU;2-3
Abstract
The effect of the dilational surface elasticity epsilon on coating was investigated in two-layer slide coatings and single-layer slot and cu rtain coating experiments, respectively, up to 2 m/s. In the slide exp eriments both the surfactant concentration and epsilon were varied in the lower layer. While the position of the static contact line (SCL) i s a function of the elasticity modulus epsilon, the dynamic contact li ne (DCL) position is insensitive to this variable. Also, the vacuum ra nge increases with increasing the modulus E. Best correlations were ob tained when epsilon was measured at 1-2 Hz with a longitudinal wave ge nerator. In curtain coating, the curtain edges can be stabilized and t he wet thickness decreased by increasing the elasticity E. Also, in sl ot coating experiments the minimum wet thickness correlates with epsil on as well. The modulus that best characterizes these coating techniqu es was determined at 0.1-0.2 Hz by means of a Langmuir trough.