Patent, page-83

I have served as an expert witness and I have had some training on IP for products.
Many companies use an incremental approach to patenting their inventions. This means that they start with the first invention which is somewhat simple and broad whilst still hopefully defining novelty. Each time the company make an improvement or a variant to their technology they create another new patent that builds on the prior art of the existing patent. This provides some retrospective protection as competitors may infringe the new patent if any aspect of what they try to use from the expired patent is overlapping to the new claims.
There is also the concept of IP protection by secrecy. If there is a perceived or demonstrably a better feature that is achieved in a way that is very hard to replicate without detailed knowledge (Cokes recipe, KFC spices etc.) then the company can protect that IP forever just by keeping it a secret.

PNV has a specific process and formula used to generate it's foam. This will not be laid out for all to see. The foam is now validated with the FDA and backed by clinical trials. That is a long road for a competitor to follow with or without patent protection.

End of story.