Rubber for lunchbox?

At the moment I’m doing a short paper on how to construct in plastics, and my group are looking at how different manufacturers design lunchboxes. Most of them are made out of PP but we found that IKEA uses synthetic rubber in their 365+ series Products - IKEA
Does anyone know what kind of synthetic rubber this is or know how to choose a suitable synthetic rubber for this purpose?

Took a look at the Ikea lunchbox. It is a double injection of what visually looks like PP or PE (tupperware) and an elastomer. There are lots of combinations that are formulated to work in double injections like this, would need to look up manufacturers recommendations.

Searching “food grade elastomers” turns up this Hytrel is fantastic material to work with.