Biodegradable Gas Barrier Films

Domenico de Angelis of Nippon Gohsei (Japan) believes their Nichigo G-Polymer™ (PVOH) makes a better gas barrier film than EVOH and in dry atmospheres it can be 50x better.  So for dry foods in controlled storage at humidities below 60% RH PVOH will outperform EVOH to an extent that downgaging  and cost saving is possible.  

PVOH gives films with glass-like transparency which biodegrade like cellulose and are therefore fully compostable.  The packaging film used PVOH as the middle layer of a sandwich with PLA as the outer layers.  There were problems with adhesion and these had been solved using a special tie resin.  The 3-layer film could also be ground and recycled as PLA; the PVOH being water soluble could be washed away. A typical construction would be 20 microns of G-Polymer inside  30micron layers of PLA each bonded to the G-Polymer with 10microns of adhesive to give an oxygen transmission rate of 0.02 ccs/square metre/day at 23C and 50%RH.

Nippon Gohsei make 70,000 tonnes/year of PVOH in Japan.  Nichigo G-Polymer™ is the world’s first amorphous PVOH and combines the strengths of regular PVOH and EVOH.