A new range of biodegradable and compostable poylvinyl alcohol (PVOH) resins and films which the developers believe could challenge the dominance of PE and other thermoplastic polymers in some packaging applications has been launched by the UK’s Polyval.
Since its establishment in 1995 the Milton Keynes firm has undertaken extensive r&d to perfect its Enpol technology, which enables the manufacture of plasticised PVOH resins and blown films claimed to offer superior performance and to be significantly cheaper than existing blown PVOH products. Polyval has significant production capacity, but in future plans licensing out the technology to film manufacturers.
Director Mike Perkins elaborates: “Blown PVOH films and resins are not new, but most companies already making PVOH products are using much older technology. Our production process is faster and cheaper, involving fewer steps, (for instance no pelletisation is required), while our formulations can be tailored to a much wider range of applications than existing films to give water solubility at temperatures ranging from 2 – 70 degs C.”
Enpol films and resins should thus, Polyval claims, be suitable for anything from water-soluble laundry bags and detergent “tabs”, to fresh produce packaging. The films will begin decomposing naturally when dissolved in water and disappear completely within 12 weeks in composting conditions.
Alongside their water solubility at a wide range of temperatures, the new films should cost up to 25% less than existing blown PVA films due to Polyval’s patented, streamlined manufacturing process, and up to 50 % less than traditional solution cast films. “PVOH films will always be more expensive than PE ones,” admits Perkins, “but conversely they can be up to 2.5 times stronger, offering significant downgauging potential.”
Other claimed benefits of Enpol films include excellent clarity and gloss, extremely low oxygen and nitrogen permeability, printability without pre-treatment and excellent anti-static properties, making them suitable for packaging delicate electronic components. They are also water permeable. When Polyval’s researchers recently compared potatoes kept in conventional PE bags with a batch kept in Enpol packs, after 18 days those in the PE packs showed significant condensation and “greening”, while those in Enpol bags were unscathed.
Perkins adds: “We are still working to perfect the sealing process for Enpol form/fill/seal bags, an area where we have had some issues due to the longer sealing times involved, but are confident of overcoming these. Otherwise the products are ready for market. Another selling point is that companies blowing conventional thermoplastics should be able to switch to the Enpol range with only minor machinery modifications.”
