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Oxo-biodegradable plastic compound used to mold closures

Closure molders have taken plenty of steps already to try to limit the environmental impact of their products, the class throwaway part. Shorter necks have greatly reduced closures' weight. Now, a U.S. company has opted for a material that helps the closures to biodegrade.

Closure molders have taken plenty of steps already to try to limit the environmental impact of their products, the class throwaway part. Shorter necks have greatly reduced closures' weight. Now, a U.S. company has opted for a material that helps the closures to biodegrade.

caps
Earth Cap closures biodegrade in two years.
The new closures are offered for now only available for 5-gallon water bottles, with Norland International Inc. (Lincoln, NE), a supplier of equipment for water bottling lines, driving the development and processing from its facility in Asia. The LDPE caps, sold under the Earth Cap trade name, contain an additive that accelerates the degradation process, resulting in total degradation in 5 -10 years.

The additives, says Sam Noordhoff, Norland's VP, are supplied in masterbatch from compounder and masterbatcher Wells Plastics (Staffordshire, England). While its Reverte-brand oxo-biodegradable products have been available from Wells for some time, this is its first use in caps, and Noordhoff says his company's processing method for these also is unique. Reverte has been used in extruded bags and films. Currently Norland molds these materials only for its 55-mm sizes, but plans to expand this to both 28mm and 30mm screw caps, with these in full production by November, he said in answer to MPW queries.  "We can also make other sizes if needed for specific applications," he added.

The caps' non-adhesive tamper-evident label and 2-mm foam seal also are biodegradable, making the entire cap structure totally biodegradable. The oxo-biodegradable caps have a two-year shelf life and offer the same performance as current versions and are also FDA compliant, reports the processor. "This is a significant milestone in meeting the sustainability needs of water bottlers throughout the world," said Noordhoff in a statement. "This is an environmentally friendly option that goes far beyond lightweighting and other recycling strategies, offering a truly effective means of reducing the environmental impact of these plastic products." His company also has partnered with Planet Green Bottle Corp. to offer oxo-biodegradable PET preforms and plastic bottles to the bottled water industry.

The Earth Cap closures, once disposed of and exposed to ultraviolet light, heat, and moisture, first become brittle and then break down into small pieces. Once the molecular weight is reduced sufficiently, the material becomes a food source for bacteria, which have a 5-10-yr meal in front of them.

The additive does not affect the caps' clarity and tensile strength. The caps will degrade in landfills, ditches, rivers, and other water sources, though naturally tossing them in a river or pond is littering. In addition, they are fully recyclable and compatible with municipal collection and recycling systems. There is no contamination with the plastics recycling stream and industrial composting facilities are not required

Norland says it is marketing these 55-mm caps at virtually the same cost as standard caps. They are commercially available in earth green, blue, and natural coloration in the U.S. and Far East/Pacific.

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