Coatings World - July 2016

provide a key to establishing a link between staining/stain repellency, the chemical nature of the substrate (coating), and the chemical nature of the staining agents.

HSP values can be estimated25 from surface energy data but the calculations are estimates at best, especially given the limited number of solvents used in this study. The surface energy analysis only determines the dispersive (Van der Waals) surface energy contribution and the total polar contribution (which in HSP is split into hydrogen bonding and polar components). Additionally, neither this study nor HSP adequately describes acid-base contributions.

This study, while not being comprehensive of all factors potentially involved (e.g., HSP, contact angle, surface energy, acid-base), does show convincingly the lack of correlation between contact angle and stain repellency. The problem is more complex and should be investigated further.

This work shows that while determina-
tion of contact angle and surface energy is
suitable for some applications like adhesive
bonding (a long term or permanent effect),
it is not appropriate as a predictive tool for
determining stain repellency in coatings.
As a result of the comprehensive study
we were able to develop a new stain re-
pellent additive for interior architectural
coatings that improves stain repellency
to household chemicals in most paints at
concentrations ranging from 1.0 to 3.0%.
This product is SILRES® BS 6500 A, for
more information contact WACKER.

Future Work

Several other components of surface properties could be investigated to determine if they have any impact upon stain repellency and correlating other surface measurements to stain repellency.