As of September 2025, customers buying Dymax UV curing adhesives containing Trimethylbenzoyl Diphenylphosphine Oxide (TPO) may notice an additional hazard sign on the product labels.
What is TPO (Trimethylbenzoyl Diphenylphosphine Oxide)?
TPO is a photoinitiator, a chemical compound that absorbs light and generates reactive species (like free radicals or cations) to start a polymerisation or curing reaction. It’s commonly found in industrial UV light curing materials like adhesive, coatings and 3D printing resins, as well as more consumer orientated products like UV nail gels. TPO is being reclassified under Commission Delegated Regulation (EU) 2024/197 from Reprotoxic Category 2 to Reprotoxic Category 1B, a stricter health hazard.
The reclassification will come into force across the EU as of 1st September 2025, and professional suppliers into the UK will harmonise with the EU rules to avoid supply chain issues. That includes updated labelling and safety data sheets, for example.
Is TPO banned in adhesives?
You may read that TPO is being banned, and that is true if you are a buyer of UV nail gels or other cosmetic products. But in the UK, there’s no specific ban planned for UV curing adhesives with TPO for industrial usage. Nevertheless, the TPO roadmap is clear (it was added to the EU REACH Substance of Very High Concern (SVHC) list in June 2023), so you will want to avoid specifying TPO containing products into new products.
Labelling
Labels on Dymax UV adhesives containing TPO currently look like this:
As of September 2025, labels on Dymax UV adhesives containing TPO may look like this:
What this means for UK manufacturers
If you are a user of materials which contain TPO, you will want to refresh your risk assessment. After curing, there is potential for free (unreacted) TPO left over. In industrial adhesives (like those used in electronics or medical devices), residual TPO is normally negligible (a few thousand ppm relative to the adhesive, sometimes only trace ppm levels) if curing is done properly. As before the September 2025 reclassification, you should follow correct workplace safety measures under COSSH to effectively manage the risk.
Support from Dymax
For the foreseeable future, you will be able to buy your TPO containing adhesives from us as usual. But Dymax is leading the way in offering TPO-free versions of its range of light-cure materials.
These TPO-free adhesives are designed to:
- Meet the latest and evolving regulatory requirements for industrial adhesives
- Mitigate your safety concerns
- Help you minimise commercial risks
We aim to support long-term product design and planning, ensuring that you stay ahead of industry changes just like this.
If you’re discussing UV curing adhesives with our sales team, there’s a good chance we’ll be able to offer you a TPO-free alternative that meets your application needs.
