Weatherability of HALS Copolymerized Acrylic Resin Precoated Steel Sheet

The deterioration mechanism of polymer outdoors is known as autooxidation caused by radical chain reaction. Fluorocarbon resin is used to improve the weatherability of precoated metal (hereafter PCM). The binding energy and the hydohobicity of fluorocarobon resin are higher than those of other organic resins, therefore the generation of alkyl radical and the hydrolysis of bonding are reduced.We have investigated the improvement for the weatherability of acrylic base PCM without fluorocarbon. We have introduced hindered amine light stabilizers (hereafter HALS) to capture the radical, and introduced cyclohexyl metacrylate (hereafter CHMA) instead of styrene or methyl metacrylate to improve the light stability and hydrophobicity. HALS was copolymerized with CHMA to prevent the flow out form paint. The newly developed HALS-CHMA PCM showed not only good weatherbility but also good corrosion resistance.