Surface functionalisation of fillers improves blanching resistance
Friday, 2 December 2011
In a new study, experimental functionalised grades of both blanc fixe and titanium dioxide reduced blanching, as predicted.
A major problem sometimes observed with powder coatings is a colour change known as 'blanching' Source: Brenda Carson - Fotolia.com
A major problem sometimes observed with powder coatings is a colour change known as 'blanching'. This is produced by water penetration into tinted powder coating systems containing inorganic pigments (titanium dioxide) and fillers (blanc fixe, barytes, GCC, etc.).
Both surface area and the modification of the inorganic particles can greatly affect the extent of blanching. Surface functionalisation of fillers and titanium dioxide with alkoxysilanes, in particular, allows covalent bonds to form between the particle surface and the surrounding matrix. This should prevent or reduce water penetration and thus protect against blanching.
In a paper included in the December issue of the EUROPEAN COATINGS JOURNAL, experimental functionalised grades of both blanc fixe and titanium dioxide were shown to reduce blanching, as predicted. No adverse effects on physical or optical properties were observed.
http://www.european-coatings.com/journal/
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