[nanoPost] Core/shell nanoparticles for scratch resistant polyurethane coatings

Company Germany

Today, coatings manufacturers have to face customer expectations, which are not in every case realizable with
conventional polymer chemistry. In the past it could be shown, that inorganic nanoparticles, e.g. in UV-curing coatings,
can lead to significant improvements of scratch resistance. The transfer of these encouraging results to polyurethane
coatings however was not always possible due to a lack of available reactive nanoparticle dispersions in suitable solvents
and due to compatibility problems.

A new approach to solve these existing problems are core/shell particles, consisting of an inorganic core and a shell of
organic polymer.

These particles can be synthesized as almost transparent dispersions in common solvents like MPA, butylacetate or
benzene up to solid contents of 80 weight% and can be formulated with a variety of polyols and isocyanates to yield
haze-free glossy coatings, even on deep black surfaces.
The widespread ‘hammer wire-wool’ test and the Daimler/Chrysler crockmetertest show that the scratch resistance of
OEM series clearcoats can be significantly increased and that spot repair coatings can achieve the scratch resistance of
coatings which were cured under OEM conditions.