Specialty Monomers to Meet the Challenges of VOC Reduced Coatings

摘要

Methacrylate monomers provide a significant contribution to comply with the increasingly stringent VOC regulations in the paint industry. Methacrylate monomers have been utilized to meet the low VOC requirements in either solvent based or water based coatings. Ambient temperature crosslinking methacrylate systems allow the user to adjust the final properties of the coatings through the post-crosslinking chemistry. The post-crosslinking chemistries of the coatings can be triggered by oxidation reaction, light induction or condensation reaction.rnThis study describes that the acrylic resins made with the oxidatively crosslinking monomers (VISIOMER® MUMA) show good film properties and good compatibility with alkyd resins, i.e. a combination of acrylic and alkyd resins compounds the advantages from both systems. The advantage of MUMA containing resins is therefore the ability to adjust a low minimum film forming temperature while still obtaining films with good mechanical properties and excellent chemical resistance. MUMA containing resins additionally can also be used for the crack bridging systems due to the high block resistance and high flexibility. Furthermore repainting aged coatings using low VOC-water based coatings may have adhesion problems as the contact surface between old and new coating remains as a sharp interlayer. VISIOMER® MEEU, an ureido functional monomer, is a key monomer to overcome adhesion problems especially to solvent based alkyd paints. The proposed mechanism of adhesion is based on an interaction between the ureido ring of VISIOMER® MEEU and the substrate via its polarity and the hydrogen bonding formation. A combination of VISIOMER® MUMA and VISIOMER® MEEU in the resins is expected to show some synergetic effects.