HALS is an abbreviation of Hindered Amine Light Stabilizers which do not absorb UV radiation but act to inhibit degradation of the polymer. light stabilizers trap free radicals once they are formed and are effective in retaining surface properties such as gloss and preventing cracking and chalking of paints. The combination with UV Absorber shows highly synergistic.
HALS include UV 622, 770, 783, 791, 944, 2020, 3808, 3853 for plastics, and UV 292, 123 for coatings.