TPO-L (CAS 84434-11-7)
| CAS No. | 84434-11-7 |
|---|---|
| Alias | Ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate |
| Category | Photoinitiators |
| Purity | ≥ 98.0% (GC) |
| Packaging | 25kg/pail |
TPO-L is a free radical photoinitiator with long absorption wavelengths (273 nm and 370 nm) and excellent deep-curing performance. It exhibits good photo-bleaching properties and low odor, making it particularly suitable for LED-curable coatings and inks. It can be used alone or with 184 to achieve a more balanced curing performance.
Equivalent grades. The same substance is sold by other manufacturers as Omnirad TPO-L, Speedcure TPO-L, Genocure TPO-L. It is the same CAS number (84434-11-7) and the same chemistry, so a formulation written around one of those grades transfers directly.
Introduction
TPO-L is the liquid form of the TPO chemistry, and for a lot of formulators that is the whole argument. It doses without a premix step, it disperses faster than a powder, and it removes the dust and weighing problems that come with handling a solid photoinitiator in a production environment.
The spectral behaviour is the same reason people move to TPO in the first place. Absorption reaches into the 370–380 nm region, which is where LED arrays actually emit. Deep cure through pigmented and thick films is the payoff, and the photobleaching keeps the cured film from holding a yellow cast.
Physical & Chemical Properties
Light yellow transparent liquid. Molecular formula C18H21O3P, molecular weight 316.34, purity ≥98.0% by GC. Absorption maxima at 273 nm and 370 nm. Not applicable melting range (liquid at room temperature).
Applications
Recommended at 1–3% in coatings and 5–10% in inks. It works well alone in LED systems and equally well blended with 184, which broadens the cure profile across the film. Because it is a liquid, loading adjustments can be made incrementally rather than by re-weighing a solid into the mill base.
Regulatory status
TPO-L's regulatory position is materially cleaner than TPO's, and that is often the real reason for the switch. It is not on the REACH Candidate List, not on Annex XIV, and was not included in the Annex XVII entry that captures TPO. It has no harmonised classification under CLP, which means any hazard information on its SDS is the supplier's own self-classification rather than an EU decision. It is not listed in Swiss Annex 10. Treat it as the pragmatic alternative rather than as permanently exempt: substances adjacent to an Annex XIV candidate have a habit of following it, and self-classification can change.
Handling & Storage
Store in a tightly closed container, cool, dry and away from light. One year shelf life from production. Consult the SDS before handling.
Packaging
Standard packaging as agreed at order; custom packaging available. COA per batch, SDS in English on request.
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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