ORGANIC LIGHT STABILIZER BLENDS FOR IMPROVED UV PROTECTION AND DURABILITY OF INDUSTRIAL AND DECORATIVE COATINGS

摘要

As illustrated with these examples of accelerated exposure tests and long-term outdoor weathering tests, light stabilizers provide an efficient solution to the UV protection and weathering resistance improvement of various coating systems. The durability increase Blends provide is depending on coating composition and noticeably on pigment levels and types. Best results in performance upgrading are obtained in general by using UVA and HALS Blends of the right types and ratios. This conclusion is valid for both clear coats and solid shades with one exception. In highly pigmented systems such as white coatings for instance, the use of HALS is practically showing similar gloss retention performances in comparison to the use of Blends. This fact can be related to the UV light absorption and reflection properties of the titanium dioxide pigment itself, which reduces the contribution of the organic UVA to the UV stabilization effect. This rule is not true for color pigmented systems which usually use much lower pigment levels and may be more transparent to UV light rendering UVA necessary. Selected UVA/HALS combinations represent in general the most cost/effective way to improve the durability of many paints and clear or transparent coatings. A range of solvent-free UVA/HALS Blends adapted to cover the requirements of a large variety of coating systems has been introduced. Easy handling and excellent performances make Blends an ideal and simple to use product class for a great number of applications. For wood coatings a new broad range UVA is introduced to meet the customers requirements of greater coating and substrate protection. In addition a new and specific HALS has been designed for wood pretreatments in order to provide further color stabilization effects . Improved weather fastness and durable color protection of natural wood are thus obtained by using the new HALS pretreatment in association with the improved UVA in top coats. The principal benefits of using light stabilizers is the elimination of premature failures, the prolongation of the coatings service life times and the possibility to differ the need for renovation.