Methyl Tetrahydrophthalic Anhydride (MeTHPA-A) Epoxy Curing Agent

MeTHPA (hexahydro) is fully saturated, providing superior UV stability and lower yellowness index (YI) after thermal aging — critical for white LED encapsulants. MeTHPA-A (tetrahydro) retains one unsaturated double bond in the ring, giving slightly lower viscosity (better wetting) but marginally higher yellowness under UV aging. For high-CRI white LEDs, MeTHPA is standard; MeTHPA-A is accepted for infrared/red LEDs or industrial EMC compounds where optical clarity is less critical.