Aliphatic Urethane Topcoat Photochemical Stability under Shortwave Retail Luminaires
Adding HALS and triazine UV absorbers to aliphatic urethane topcoats prevents shortwave retail LED yellowing and blocks unsaleable display chargeback deductions.
Free Radical Photo Oxidation
Meaning
Chemical reaction pathways describe the degradation of polymers and coatings caused by the absorption of ultraviolet and violet light in the presence of oxygen. Materials used in retail fixtures are subject to free radical photo oxidation, which results in yellowing, cracking, and loss of structural strength. This chemical degradation process does not apply to inorganic materials such as glass or stainless steel.
Chemical Degradation
Appearance standards are compromised when plastic components degrade due to light exposure. The prevention of free radical photo oxidation requires the use of chemical stabilizers during manufacturing to maintain the product’s appearance. This ensures that the display remains attractive to shoppers.
Material Warranty
Warranty terms in supply contracts specify the maximum allowable color shift and degradation of plastic fixtures over time. If a supplier fails to include UV stabilizers, free radical photo oxidation will cause the display to degrade prematurely, triggering warranty claims and product returns. The distributor can demand that the supplier replace the yellowed fixtures at no additional cost.
This risk forces the manufacturer to verify the chemical composition of the plastics before shipping the products to the store.
Contractual Protection
Liability for light-induced damage is assigned to the manufacturer if the materials do not meet the agreed specifications. This protects the buyer’s investment.