2959 is an α-hydroxy-ketone Type I photoinitiator bearing a hydrophilic 2-hydroxyethoxy tail. It shows strong UV-A absorption (λmax ≈ 275 nm, shoulder 320 nm) and undergoes efficient α-cleavage to give benzoyl and methyl radicals, initiating rapid polymerisation of acrylates, methacrylates and other vinyl monomers. The product is water-soluble (≈ 7.6 g L⁻¹ at 25 °C), low-volatility and FDA-approved for indirect food-contact applications. Commercial material is supplied at ≥ 99 % purity and remains stable for ≥ 2 years when stored sealed at room temperature in the dark .
Key Physicochemical Data:
Melting point: 88–90 °C
Density: 1.183 g cm⁻³ (predicted)
Flash point: 156 °C (predicted)
Log P (octanol/water): 0.84 at 23 °C
Vapour pressure: < 0.001 mmHg at 25 °C
Typical Uses:
Universal Type I photoinitiator for UV-LED or mercury-lamp curing of water-borne and powder coatings, inks, adhesives, dental composites and biomedical PEG hydrogels at 2–5 % w/w; features low odour, low yellowing and excellent through-cure .
Reactive hydroxyl group allows covalent grafting to polymers or particle surfaces for permanent UV stability .
Reference standard for analytical determination of photoinitiator residues in food-contact materials .
Quality Specification (Commercial Grade):
Purity (HPLC): ≥ 99 %
Water content (KF): ≤ 0.3 %
Loss on drying: ≤ 0.5 %
Residue on ignition: ≤ 0.1 %
Heavy metals: ≤ 20 ppm
Hazard Statement:
Toxic to aquatic life with long-lasting effects (H411) . Avoid release to the environment; collect spillage (P391). Store in a cool, dry place away from oxidants and light. SDS available on request.
