NPI-601 (CAS 162881-26-7)
| CAS No. | 162881-26-7 |
|---|---|
| Alias | Bis(2,4,6-trimethylbenzoyl) phenylphosphine oxide |
| Category | Photoinitiators |
| Purity | ≥98.00% (HPLC) |
| Packaging | 20kg/carton |
NPI-601 is a general free radical photoinitiator based on phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. It offers high curing activity, long absorption wavelengths (377 nm and 405 nm), and excellent deep-curing and photo-bleaching performance. It is particularly suitable for LED-curable coatings and inks, and is often used as a more active complement to TPO.
Equivalent grades. The same substance is sold by other manufacturers as Omnirad 819, Irgacure 819 (BAPO). It is the same CAS number (162881-26-7) and the same chemistry, so a formulation written around one of those grades transfers directly.
Introduction
NPI-601 is a bisacylphosphine oxide, known in the market as BAPO and sold by others as 819. Its absorption reaches 377 and 405 nm, which is further into the visible than TPO manages, and that has a direct consequence: it cures under the 395 and 405 nm LED arrays that are increasingly standard, and it cures deeply.
It is usually described as a more active complement to TPO rather than a replacement. The two are often blended, and the combination gives a cure profile that neither achieves alone. If your LED line struggles with through-cure in a pigmented film, this is the grade to test.
Physical & Chemical Properties
Light yellow powder. Chemical name bis(2,4,6-trimethylbenzoyl) phenylphosphine oxide. Molecular formula C26H27O3P, molecular weight 418.46, purity ≥98.00% by HPLC, melting range 127–135 °C, loss on drying ≤0.50%. Absorption maxima at 377 nm and 405 nm.
Applications
Recommended at 1–3% by weight. Suited to LED-curable coatings and inks, deep-cure applications, and pigmented systems. Good photo-bleaching behaviour keeps the cured film from holding a yellow cast.
Regulatory status
NPI-601 has no harmonised classification under CLP, is not on the REACH Candidate List, and is not restricted under Annex XVII. It is not listed in Swiss Annex 10. Note that the substance it complements, TPO, has a significantly more complicated regulatory position; if you are blending the two, check both.
Handling & Storage
Store sealed, cool, dry and dark. Consult the SDS.
Packaging
20 kg cartons. COA per batch, SDS in English, samples available.
Applications & Industries
Coatings & Paints
Metal driers (cobalt, manganese, zirconium octoate, naphthenates) and photoinitiators for coatings, paints, varnishes and industrial finishes — with COA & MSDS per batch.
UV Curing & Printing Inks
Free radical photoinitiators for UV-curable inks, coatings, adhesives and 3D printing — 1173, 184, 369, 907, ITX, DETX, TPO/TPO-L and liquid blends, QC-tested per batch.
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