Chemical name: Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide CAS No.:75980-60-8 Molecular formula:C22H21O2P Molecular weight:348.37 Appearance: Pale yellow crystal powder Purity, %: ≥99.0 (HPLC) Melting point,℃:91.0-94.0 Volatility, %: ≤0.2 Acid value (mgKOH/g): ≤0.5 TPO is an efficient free radical photoinitiator with absorption in a long wavelength range. Its effective absorption peak is 350-400nm and it always absorbs about 420nm. Its absorption peak is longer than that of the conventional initiator. After irradiation, two free radicals, benzoyl and phosphatidyl, can be formed, which can initiate polymerization. It is a photoinitiator for curing styrene-based unsaturated polyesters and acrylic resins. Its absorption in the long-wave region of the UV spectrum can fully cure even white paints and surfaces pigmented with TiO2. Such coatings are characterized by particularly low yellowing. TPO can also be used to cure clear coatings and is particularly suitable when low-odor products are desired. Recommended applications: screen inks white coatings, flexo inks wood coatings, overprint varnishes printing plates etc.The thermal stability of TPO is excellent. It is heated to 180℃ without chemical reaction and has good storage stability.