The unsung polymer: polyvinyl alcohol

14 March 2012



David Edwards, founder and chief executive of Edwards Innovations, says PVOH is the packaging industry’s best-kept secret


Sustainable packaging solutions are in great demand, due largely to diminishing landfill resources and stringent legislative pressure. These sustainable solutions need to take into account performance, convenience, safety, and brand identity. While other options of so-called biodegradable plastics exist, there is a material that appears to be the industry’s best-kept secret: polyvinyl alcohol (PVOH).

Unlike so many other biodegradable plastics, PVOH ‘does what is says on the tin’. Not only does it have credible credentials on the biodegradable front, but its performance figures are second to none when compared with other options.

PVOH is the most widely used polymer for the manufacture of water-soluble films and moulding compounds. Dissolution times for PVOH films and compounds can be controlled for use in hot or cold water and for some applications it can be formulated to be insoluble.

PVOH film made a significant contribution to the packaging industry in 1989. Water-soluble film enabled the creation of a novel measured delivery system to elegantly address operator exposure issues associated with the handling of pesticides. This packaging system was heralded as a breakthrough technology and led to rapid development of advanced films and processes, including measured delivery of liquid pesticides. This concept was then mirrored by the detergent industry for the unit dosing of detergents known as ‘liquid tabs’. MonoSol is a world leader in the manufacture and marketing of PVOH films and compounds.

Today, polyvinyl alcohol applications are extremely diverse, ranging from film used in feminine hygiene and adult incontinence products to resin solutions for use in personal care, such as eye drops and contact lens wetting solutions as a lubrication aid. In addition to water solubility, PVOH resins have a unique set of physical, mechanical, and chemical properties that provide this versatility.

Packaging properties

PVOH films and compounds are highly resistant to oil, grease and solvents. For example, MonoPol PVOH compounds can be moulded into containers to hold oil or solvent liquids yet will dissolve in water.

PVOH films and compounds also have excellent oxygen and aroma barrier properties. Applications using this property include everything from keeping foods fresher longer to keeping perfumes and aromas contained until the time of use.

While many packaging materials cannot be recycled, PVOH can be dissolved in the paperboard recycling process. Imagine a packaging system using board and PVOH film for fragile products. After use, the consumer would be able to recycle the packaging in the paper recycling stream – which already uses PVOH resins.

The amazing properties of PVOH resins and films provide benefits in a diverse array of other applications, including:

» Water-soluble bait bags used by anglers to contain oil-based bait, which provides controlled release into the water.

» Hospitals around the world safely contain soiled linens in water-soluble laundry bags, which are delivered directly to an industrial washing machine. During the washing cycle, the load is released and cleaned, while the water-soluble bag dissolves in the hot wash water.

» PVOH compound is used to make novel injection moulded capsules for drug delivery systems, providing an alternative to gelatine capsules.

» PVOH bags provide convenience to many applications in agriculture, horticulture and the home garden. Examples include the precise dosing of active ingredients such as herbicides, fertilisers, and seeds.

» PVOH film is used in the water transfer printing process to decorate 3-D objects, including wood-grain for car interiors and designs for recreational vehicle parts.

With the world focused on developing environmentally-friendly solutions, the future of this remarkable material is an exciting one.

Contact

David Edwards Finst Pkg CSci – founder and chief executive of Edwards Innovations. Innovator and developer of more than 60 patents involving PVOH. Many are household names.

» david-colt@hotmail.com

Views expressed on this page are those of the author and may not be shared by PVOH applications this publication.


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