Chemical Name: 2,4,6-Trimethyl benzoyldiphenyl phosphine oxide
Molecular Formula: C22H21O2P
Molecular Weight: 348.382 g/mol
CAS No: 75980-60-8
EC No: 278-355-8
Synonyms: Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, Photocure TPO, 2,4,6-Trimethylbenzoyl diphenylphosphine oxide, biphenyl(2,4,6-trimethyl-benzoyl)-phosphine oxide


Molecular Structure


Syna-PI TPO is a radical photoinitiator that can be used alone or in combination with other photoinitiators. It is used in formulations containing unsaturated materials such as acrylates, methacrylates, vinyl’s and unsaturated polyesters. With exposure to UV light, Syna-PI TPO undergoes a photochemical reaction that generates radicals. These radicals will initiate polymerization through the unsaturated groups present in the system. Syna-PI TPO, due to its photo- leaching properties, is especially suited for the UV curing of white pigmented formulations and thick clear coatings. Syna-PI TPO is frequently combined with other alpha cleavage photoinitiators such as Syna-PI 184 and Syna-PI 1173 for improved surface cure.


Syna-PI TPO is typically used at levels of 0.5-2% by weight based on the reactive components of the formulation.  Application included:
•  Screen inks, particularly white
•  White flexographic inks
•  White offset inks
•  Thick (~0.25 mm or greater) clear coatings
•  Pigmented coatings, particularly white

            Product Specification:

Term Specification
Appearance Slightly Yellow Crystalline Powder
Purity >= 99.0%
Melting range ºC 91-94
Volatiles <= 0.20 %
Shelf Life Two Years
Printable TDS Version SDS