2,4,6-trimethylbenzoyl diphenylphosphine oxide

2,4,6-Trimethylbenzoyl diphenylphosphine oxide, commonly known as TPO, is a monoacylphosphine oxide photoinitiator that triggers free-radical polymerization upon UV or visible light exposure. It is used across UV-curable systems to initiate rapid crosslinking and curing without thermal activation. In UV-curable coatings for wood, metal, and plastic substrates, TPO delivers fast surface cure and low yellowing, making it a preferred choice for clear and pigmented finishes. This chemical, identified by CAS 75980-60-8, is essential for modern industrial coating processes.

Printing inks, particularly LED-UV and broad-spectrum UV inkjet and offset formulations, rely on TPO for its strong absorption in the 380–420 nm range. This specific absorption profile enables high-speed curing on press, which is vital for high-volume commercial printing operations. In adhesives and sealants, it supports through-cure in acrylate-based systems where depth of cure and bond strength are critical performance requirements. This ensures that the structural integrity of the bond is maintained even in thick layers or opaque formulations.

Dental composites and optical fiber coatings also use TPO where controlled, rapid photopolymerization is required in precision applications. Its ability to cure effectively under visible light makes it a versatile component in medical and telecommunications manufacturing. TPO is supplied as a light yellow to yellow crystalline powder. Standard commercial grades are available at high purity, typically ≥98–99%, for industrial and specialty applications requiring consistent chemical performance and stability.

It is commonly offered in technical and photoinitiator-grade specifications to meet various industrial needs. Packaging options range from kilogram quantities to bulk drums suited for large-scale formulation operations and global supply chain requirements.