184 is an α-hydroxy-ketone Type I photoinitiator that exhibits strong UV-A absorption (λmax ≈ 250–330 nm). Upon irradiation it undergoes α-cleavage to give benzoyl and cyclohexyl radicals, initiating rapid, low-odour, low-yellowing polymerisation of acrylate, methacrylate and other vinyl monomers. The product is sparingly soluble in water (≈ 1.1 g L⁻¹ at 25 °C) and freely soluble in acetone, methanol, toluene and most UV-curable resins. Commercial grade is supplied at ≥ 99 % purity and remains stable for ≥ 2 years when stored sealed at room temperature away from light .
Key Physicochemical Data:
Melting point: 47–50 °C
Boiling point: 175 °C / 15 mmHg
Density: 1.17 g cm⁻³ (20 °C)
Flash point: > 150 °C (closed cup)
Log P (octanol/water): 2.81 at 25 °C
Vapour pressure: 0.02 Pa at 20 °C
Typical Uses:
Universal Type I photoinitiator for UV-LED or mercury-lamp curing of clear and pigmented coatings, inks, adhesives, wood finishes, optical-fibre coatings and dental composites at 2–5 % w/w; features low yellowing and extended shelf-life .
Photosensitiser for thick-section (> 4 mm) and highly coloured formulations with excellent through-cure .
Building block for UV-curable hydrogels, stereolithography resins and food-contact packaging materials approved by FDA .
Quality Specification (Commercial Grade):
Purity (HPLC): ≥ 99 %
Water content (KF): ≤ 0.3 %
Loss on drying: ≤ 0.1 %
Ash: ≤ 0.2 %
Colour (Hazen): ≤ 50
Heavy metals: ≤ 20 ppm
Hazard Statement:
Causes skin irritation (H315) and serious eye irritation (H319) . Avoid dust formation; use gloves, goggles and adequate ventilation. Store in a cool, dry place away from oxidants and light. SDS available on request.
