Polyurethane foam, a widely used soft foam material, is prone to yellowing over time.
What we call yellowing-resistant foam now usually refers to the addition of antioxidants, heat stabilizers and light stabilizers during foaming production, which can temporarily slow down the rate of yellowing of the foam.
But there are really effective solutions here, so please read on.
1. The Cause of Yellowing
Yellowing primarily occurs due to the gradual oxidation of the benzene ring on the isocyanate in polyurethane foam. And, the foam's molecular chains contain coloring groups such as carbonyl, amino, azo, and alkene, which selectively absorb and emit certain wavelengths of light. This leads to a degree of yellowing in the foam.
2. Effective Solution to Yellowing
The most effective way is to use non-yellowing aliphatic ISO for foam production,such as IPDI, HDI, and HMDI, form more stable urethane bonds.
Even if they decompose into aliphatic amines, they do not possess benzene ring conjugation structures, which means they do not form color-enhancing groups.
Moreover, aliphatic amines are less prone to oxidation, reducing the likelihood of yellowing.