Low-migration UV-curable resins for food packaging compliance
What challenges are faced by modern food packaging ink formulators?
Amid tightening sustainability targets and regulations, UV-curable resins are an increasingly attractive food packaging solution, as their fast, energy-efficient curing cuts VOC emissions and cost compared with thermal-cure alternatives.
However, fast UV curing requires the addition of a photoinitiator: a highly reactive molecule that carries the risk of migration into food. Conventional formulations default to polymeric photoinitiators (PPIs), which reduce that risk but don't fully eliminate it, or to high-SML (specific migration limit) photoinitiators, which come with higher packaging formulation costs.
How does NeoRad™ S-8100 reduce the risk of migration?
NeoRad™ S-8100 addresses this trade-off, as it is a self-initiating resin (SIR). SIRs build the photo initiating moieties directly into the resin acrylate backbone, so there's minimal to zero possibility for migration to food.
This is not only an advantage over traditional UV-cured resins, but also sets NeoRad™ S-8100 apart from other SIRs on the market, which are typically based on benzophenone chemistry and require an additional amine synergist. NeoRad™ S-8100 isn't based on benzophenone and needs no additional amine. This means one less formulation variable to test, and less of the yellowing that amine-boosted systems typically bring.
Self-initiating resins are still growing in demand, and formulators want to move away from chemistries that merely reduce migration risk toward those with nothing left to migrate. That's the customer need that NeoRad™ S-8100 is built to fulfil.
How does NeoRad™ S-8100 support cost-effective, high-performance food-contact materials?
As a low-viscosity acrylate, NeoRad™ S-8100 is miscible and easily compatible with other acrylates across flexo, OPV, and offset printing alike. This also means formulators don't need to add extra low-molecular-weight monomers to adjust viscosity. These monomers are a common source of migratable residuals in radiation-curable systems.
In flexo inks and OPVs, NeoRad™ S-8100 shows better cure speed and lower yellowing than competing SIRs, and comparable-to-better performance against PPI systems across cure speed, adhesion, solvent resistance, color strength, and gloss. Formulations are also low-toxic and low-VOC, and suitable for a wide range of sensitive applications. This makes NeoRad™ S-8100 a cost-effective path to achieving safer food-contact materials without compromising on performance.
How does NeoRad™ S-8100 comply with current and upcoming food-packaging regulations?
NeoRad™ S-8100 is a REACH- polymer, and its raw materials meet the food safety criteria set out in the Swiss Ordinance and the German Ink Ordinance. Worst case migration and extraction testing supports suitability for low-migration applications, including indirect food contact. Because the chemistry itself is safe by design, rather than assessed on a formulation-by-formulation basis, customers can also avoid the cost and delay of repeating migration testing every time they adjust a recipe.
How does support from Covestro help enable compliant UV-cured food packaging materials?
Guideline formulations from Covestro provide starting points for flexo, OPV, and offset applications, already balanced for target viscosity. This allows formulators to experience how NeoRad™ S-8100 behaves in combination with other formulation components. Samples are also available through a Covestro representative for testing in-process.
NeoRad™ S-8100 is optimized for UV light curing today, but for formulators tracking the industry's shift toward LED light curing, Covestro can also share more about our ongoing development work in this area.
Key benefits
- Low-to-zero migration: Photoinitiating chemistry is built into the acrylate backbone.
- Low viscosity: Enables compatibility with other acrylates across flexo and offset printing, as well as OPVs.
- Fewer additives: No additional amine synergists required, reducing yellowing.
- Regulation compliant: Meets Swiss Ordinance and German Ink Ordinance food-contact requirements.
- Cost-effective: Versatility across flexo and offset applications, ease of miscibility and no need for additional synergists enable low total cost of ownership.
