Incorporating Nanosilica Technology of Different Particle Size for New Improvements in UV-Curable Coatings

The blending of mineral fillers with organic polymeric materials typically provides highly improved mechanical and physical properties of the cured polymer. Unfortunately, the use of conventional mineral filling materials (e.g. quartz flour or fumed silica) is usually accompanied by cost- and energy-intensive dispersion technologies. These conventional fillers could potentially give a dramatic viscosity increase within the formulation and hamper, or even prohibit, processing. In addition, some properties of the cured material are negatively affected like brittleness and transparency. To overcome the disadvantages of conventional mineral fillers, extensive research and development efforts have yielded nanosized mineral filling materials with an average size of 1-100 nm. These nanosized particles proved to dramatically reduce formulation viscosity and thereby enhance mechanical and optical properties of the cured organic polymer. Thus, it was possible to improve the scratch resistance and hardness of UV-cured coatings while simultaneously keeping the optical transparency equivalent to unfilled materials[1].

To homogeneously disperse nanosized mineral particles in an organic matrix, it is usually necessary to modify the particle surface with organic reagents. This organic modification compatiblizes the nanosized particles with the organic resin whichprevents agglomeration.[2] After significant research, an efficient and reliable route to surface modify silica nanoparticles in a variety of reactive organic monomers and oligomers has been established. The unique ability to modify the silica nanoparticles allows incorporation of silica up to 50 pbw[3]. The particles proved to be homogeneously dispersed in the organic matrix exhibiting a small size and a comparably narrow particle size distribution. These silica nanocomposite materials require no special dispersing equipment and are suitable raw materials for coatings, adhesives and fiber composite materials[4-6]. The objective of this paper is to present and demonstrate the enhancing properties of silica nanoparticle modified acrylates (free-radical UV-curing) with different particle sizes for UV-curable coating materials. These high performance materials are utilized in furniture, flooring, automotive, communication and engineering applications where transparency and scratch/abrasion resistance of different test methods are imperative.