Yellowing in polyurethane foam can be attributed to various factors and falls into four main categories:
1.UV-Induced Yellowing: This occurs when the foam is exposed to ultraviolet (UV) light.
2.Fabric Contamination: Yellowing may result from contaminants present in the fabric used in the foam.
3.Gas Fumigation: Exposure to nitrogen oxides in the air can lead to gas fumigation yellowing.
4.Thermal Oxidation: High temperatures during foam production or processing can cause thermal oxidation yellowing.
Addressing these yellowing issues is often closely linked to the presence of antioxidants. Therefore, solutions to mitigate yellowing primarily involve the use of additives:
1.Opt for High-Performance Polyethers: Choose polyethers that are free from BHT or amine-based antioxidants, which can help reduce susceptibility to yellowing.
2.Enhance Heat and UV Resistance: To further improve resistance to yellowing, it’s essential to bolster the foam’s ability to withstand heat-induced yellowing during the foaming process and enhance its resistance to UV-induced yellowing after thermal compression molding.
