So here we have it yet again! Plastics come to the rescue of “environmentally-friendly” paper-based packaging solutions, delivering sealant and potentially barrier properties unattainable with paper alone. It kind of reminds me of that Coca-Cola paper bottle with the plastic liner. Seriously, what is being achieved here?
So back to the latest development that manages to combine a plastic sealant layer and unidentified barrier coating with a paper substrate to realize a “recyclable” barrier packaging for coffee, cookies, and what-have-you, with equivalent barrier performance to EVOH or PVDC to boot.
A May 11 announcement by Mitsubishi Chemical revealed that its bio-based polybutylene succinate (PBS) resin, aptly branded BioPBS, had been employed as the sealant layer for the paper-based barrier material SILBIO BARRIER from Japan’s Oji F-Tex. Nothing new about that. Traditional paperboard packaging solutions require plastic sealant resins that can also protect the paper from the packaged contents.
But what about the paper barrier material? Details are sparse so we don’t actually know its composition, which surprises me. If it’s good for the environment why not identify the material rather than shroud it in mystery? Whatever this barrier material is, it's surely not paper-based so you could be dealing with a structure of paper, plastic and something else.
What we do know about a sister product and transparent paper-based barrier material, SILBIO CLEAR, is that according to Japanese patent 693064, it combines a paper layer and a plastic layer that functions as the sealant and barrier in one, the latter being selected from either a polyolefin, a polyester, a polyamide, or a biodegradable polymer.
What also intrigued me about SILBIO BARRIER was a link to a video in Japanese describing it merits. One of them, almost laughably, is that it can be laminated with polyethylene and polypropylene but “because the paper component has a higher density than the plastic laminate, you are able to label the packaging structure with the paper recycling mark and as such, it is recognized as a non-fossil-fuel-based sustainable material.” So in effect you are getting most of the benefits and functionality from plastics but at the time you can sneak it through as paper packaging.
With all these developments we are almost lost for breath, But it does seem that in these quests to promote sustainability, the opposite has happened, with complicated multimaterial structures that hardly appear sustainable.
Image: Oji F-Tex