No, compostable or biodegradable PVC does not exist.
Yes, cardboard alternative exists, but it needs lamination in order to be rigid enough to hold the collar of the shirts: in facts, for its nature, it absorbs moisture that makes it fragile. For obvious reasons, if laminated, the board would lose its "sustainable" characteristics (provided that the exploitation of this resource is considered sustainable), and would then be disposed of in general waste (always under the indications of its own municipality).

Other types of plastic material could be used, but the choice of PVC is dictated by its technical characteristics, by its conformity, workability and strength that guarantees excellent performance. For this reason PET interlays strips are not on market (too expensive production that would increase the prices of the product), as well as PS supports (fragile material subject to breakage due to temperature changes), or other plastic materials.

But let's go back to the original question:

if PVC is already the most ecofriendly material?

In fact, at the end of production through our grinders, PVC waste is shredded becoming secondary raw material and in agreement with these companies, the material is used for different applications. For example, pipes, PVC conduits, injection molded accessories and much more are generated.