Nanoclay modified waterborne compositions for coating plastic and methods for making the same

摘要

The present invention provides aqueous dispersion compositions comprising one or more than one of each of aqueous dispersions of water-dispersible polymers and aqueous nanocomposite dispersions of at least partially exfoliated layered silicates and water-insoluble polymers to enhance the thermal shock resistance of a waterborne coating, film, or article comprising the composition. Only 2 to 10 phr of the layered silicate, e.g. sodium montmorillonite surprisingly enhances thermal shock resistance. Optional fillers, such as nepheline syenite, may be added. Such compositions may be coated on automotive plastic, TPO or resinous substrates, and provide coatings having a 19 or greater thermal shock resistance according to Ford laboratory test method BI 107-05 when coated on TPO and baked for 15 minutes at from 74 to 90° C. Further, the present invention provides methods of making aqueous nanocomposite dispersions comprising mixing unmodified layered silicate and water insoluble neat resin in water to at least partially exfoliate the clay and subjecting the resulting mixture to high shear.