ØWhat problems will occur in coatings without added UV absorbers?
Under outdoor conditions, some coatings undergo light aging after long-term sunlight exposure in a few months or years, showing problems such as loss of gloss, color fading, chalking, cracking, and even peeling off the whole layer. This seriously undermines the decorative of coating and protective effect on the substrate. Not only the economy suffered a great loss, resulting in a waste of resources, but also the aging degradation of resin cause some pollution. The underlying problem is the lack of or improperly selected UV absorbers added to the coating.
ØWhy does UV aging occur in coatings?
Aging of coating resins usually occurs under the influence of a combination of environmental factors, such as light, heat, water, oxygen, inorganic salts, etc., all of these factors contribute to the degradation of the resin. However, among them, solar UV radiation is the most significant factor leading to polymer degradation. UV radiation causes degradation reactions on the exposed coating film resulting in loss of gloss, discoloring, chalking, flaking of the coating, etc.
ØHow to solve the problem of UV aging of coatings and obtain high quality coatings?
Preventing photodegradation of coating resin triggered by UV light is the key to improve its UV aging resistance. Choosing suitable UV absorber is the most convenient and economical way to prevent coatings. Adding UV absorbers to the coating can effectively inhibit or reduce the photo-oxidation reaction of the resin, thus significantly improve the weathering resistance of the coating, slow down the UV aging and extend its service life.
UV absorber for coatings should have the following features:
> Wide absorption range at UV wavelengths of 290-400nm;
> Good light stability, even under long-term exposure to sunlight, its absorption capacity is almost not reduced;
> Good thermal stability, no property reduction due to heat during processing and use;
> Good compatibility with resin, no exudation during use;
> Eco-friendly, low toxicity, low volatility.
Currently, Benzotriazole UV absorber is the most widely used UV absorber in the coating industry thanks to its wide UV absorption range, good compatibility and other advantages.
OMNISTAB Liquid Benzotriazole UV Absorbers for coating：
OMNISTAB UV1130 is widely used in automotive and industrial coatings with high weatherability requirements. It’s easy to emulsify and could be applied in both water-based and solvent-based systems.
OMNISTAB UV384-2 is designed for high performance coatings, which meets the durability demand of automotive coatings, and achieve the quality required for premium topcoats. It provides effective protection for primers as well as wood or plastic coating. In addition, it has excellent heat resistance, so it particularly suitable for coatings that are subjected to long baking periods and extreme external conditions. OMNISTAB UV384-2 is mainly used in solvent-based coatings.
OMNISTAB UV571 is used for polyurethane coating, which effectively improve the yellowing resistance level of coating.
All above UV absorbers are liquid and when used in combination with HALS(like OMNISTAB LS292, LS123), these synergistic combinations impart superior protection against gloss reduction, cracking, blistering and discoloring.
For more information about the use of above UV absorbers, please consult us or visit our official website. Looking forward to your inquiry!
