Scion Bioplastics (Net Vine Clips)

Crown Research Institute Scion has developed a faster-degrading bioplastic product for use in the wine industry, using a waste product from the wine industry.

PLA (polylactic acid) is the least expensive and most widely available bioplastic – made from renewable resources (like sugar cane or corn starch). The bioplastic is soft when heated and solid when cooled. Because of this, it can be extruded into various shapes and is often used in 3D desktop printing.

Common products made from PLA include cups, plastic bags, cutlery and medical implants. It is biodegradable under certain conditions. In industrial composters PLA will break down in 180 days (but that requires temperatures of around 60 degrees Celsius and the addition of digesting microbes). In water, it takes around 48 months to breakdown. In a domestic compost bin, or tightly packed landfill, it has been estimated that it could take between 100 to 1,000 years to breakdown into carbon dioxide and water.

Other bioplastics exist, like PHAs and bio-PBS, that are home compostable and soil biodegradable, but these are more expensive than PLA, which limits their use. Bioplastics are increasingly being used as an alternative to petroleum-based plastics. But some bioplastics are more biodegradable than others, and it is this property that can be exploited in various applications.

Scion’s Biopolymers and Chemicals specialises in formulating bioplastics to meet mechanical and biodegradation requirements for a wide range of applications, especially in single-use plastics.

Scion approached Villa Maria Wines to find out where the opportunities lay in the viticulture industry around potential uses of biopolymers. Net clips (the kind used as bread bag closures) were identified as one such opportunity.

Villa Maria has a focus on sustainability throughout their operation and provided grape marc as raw material for Scion’s formulation development for this application. Marc is the skins and seeds left after the grapes have been crushed and is a significant waste product of the wine industry.

Market studies have estimated that around 16.8 million plastic clips are used each year in the New Zealand wine industry. They are used to hold nets over ripening bunches of grapes to prevent loss from birds and other pests attracted by an all-you-can-eat buffet in the vineyard.

The net clips are required for about 6 – 8 weeks to hold the nets in place. Because of their size and number, it is uneconomic to collect and recycle the plastic clips, which generally fall to the ground as the nets are rolled up and put away for the following year. This leaves a growing pile of non-biodegradable clips in vineyards around the country.

Led by researcher, Steph Weal, Scion has developed and trialed a grapevine net clip made from grape marc and bioplastic. The trials have been running for two years (since 2016).

The addition of marc to the bioplastic formulation results in more rapid degradation than PLA or bioplastic alone. The addition of PLA to the formulation gives the resulting bioplastic formulation the necessary mechanical strength for the application.

Trials were undertaken at Villa Maria’s Te Awa vineyard in Hawke’s Bay.

At the Scion lab, marc and bioplastics were combined and extruded into sheets and then rolls that were laser-cut for the trials.

Currently a stamping cutter is being created to scale up the trials. Gildas Lebrun is leading the scaling-up work. He has previously introduced kiwifruit skins into PLA to create biodegradable “spives” for Zespri to put into their organic kiwifruit packages. 

The hope is that one of the two companies in the world (one based in the US and one in the Netherlands) that make petroleum-based plastic clips for bread bags (and vineyard nets) will take up the formulation for the more readily biodegradable product - or that a New Zealand company will take up the manufacturing challenge.