Photoinitiators
Photoinitiator BDK (651)
2,2-Dimethoxy-2-phenylacetophenone
The classic benzil dimethyl ketal — efficient Type I cure at economical cost.
Product Description
BDK, widely known as photoinitiator 651, is one of the earliest commercial Type I photoinitiators. Benzoin-type photolysis yields two benzoyl radicals per molecule with high quantum efficiency, providing fast, economical cure in clear and lightly pigmented systems.
Its main considerations are a moderate yellowing tendency at high loadings and limited thermal stability above ~60 °C, so it is best used in systems cured promptly after formulation. Typical use: 2–4 wt% in clear coatings, PCB marking inks and adhesives.
Key Features
- High radical yield — two radicals per molecule
- Very economical at typical loadings
- Decades of formulation history and data
- Efficient under both mercury and LED UVA sources
Applications
- Clear and white UV coatings
- PCB marking and legend inks
- UV adhesives
- Paper coatings and overprint varnishes
- Photopolymer printing plates
Specifications
| CAS No. | 24650-42-8 |
|---|---|
| Molecular Formula | C16H16O3 |
| Molecular Weight | 256.30 |
| Appearance | White powder or crystals |
| Assay (HPLC) | ≥ 99.0% |
| Melting Point | 64 – 67 °C |
| Loss on Drying | ≤ 0.5% |
Packaging & Storage
25 kg fiber drum with PE liner, 1 kg aluminum-foil sample bag. Store cool (below 40 °C), dry and protected from light; shelf life 24 months.
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