BDK is a benzil dimethyl ketal that functions as a highly efficient Type I photoinitiator for UV-LED or mercury-lamp curing. Upon irradiation (250–400 nm) it undergoes α-cleavage to yield two active benzoyl and methyl radicals, initiating rapid polymerisation of acrylates, methacrylates, styrene and other unsaturated monomers. The product is practically insoluble in water and stable under neutral to slightly alkaline conditions; it should be protected from strong acids and oxidants. 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: 64–67 °C
Boiling point: 169 °C / 7 mmHg
Density: 1.122 g cm⁻³ (20 °C)
Flash point: > 110 °C (closed cup, predicted)
Log P (octanol/water): 3.3 (predicted)
UV absorption: λmax 250–330 nm (high ε)
Typical Uses:
Universal Type I photoinitiator for UV-curable inks, over-print varnishes, wood coatings, adhesives and 3-D printing resins at 0.5–5 % w/w .
Photosensitiser for thick-section (> 4 mm) and pigmented (black/red) systems with low yellowing and excellent through-cure .
Intermediate for synthesising benzoylformate derivatives and UV-absorbing monomers .
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:
Causes skin and eye irritation (H315 + H319); harmful to aquatic life with long-lasting effects (H413) . Avoid dust formation; use gloves, goggles and adequate ventilation. Store in a cool, dry place away from oxidants and strong acids. SDS available on request.
