Sustainability in Plastics—Embracing New Approaches

Contact Author Chris Pandis
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Over the past decade, green choices such as sustainable living, goods made from renewable and recyclable materials, and product stewardship have moved from the realm of study and debate to become almost universally accepted. The concept of global climate change is accepted as fact, and the remaining doubters are mostly regarded as part of a radical fringe. Earth centric thinking is becoming a critical part of everyday life.

It is no wonder, then, that makers of high-volume consumer goods, including beauty and personal care products, have sharpened their focus on sustainability and shifted from making rather ad hoc efforts to appear green to developing clear environmental policies with real and verifiable objectives. Procter & Gamble, for instance, is one brand owner that has publicly committed to long-term goals of reducing energy consumption, converting entirely to renewable energy sources, using 100% renewable or recycled materials, and eliminating disposal of consumer and manufacturing waste in landfills. Unilever reports that, by 2020, it will reduce the weight of packaging by one third, cut landfilled waste in half, and reduce greenhouse-gas emissions associated with their products by 50%.

Early efforts to produce green products and packaging were driven mainly by marketers who saw the advantage in connecting with consumers concerned about the environment. In many cases, however, they fought an uphill battle against purchasing people who saw higher costs compared to more conventional materials, production staff who found the alternative materials to be difficult to process, and designers who found limited choices in color and other appearance elements. A compromise had to be reached between sustainable objectives and the reality of economics, production and aesthetics.

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Not so today. While the efforts of some brand companies may have started as a response to consumers concerned about the environment—and while they may still be presented under the banner of corporate responsibility—these changes are now being driven as much by economics as by ecology. Cutting material and energy use is not just environmentally responsible, it is also fiscally rewarding.

Putting Plastics on a Diet

As noted, a key sustainability objective for many companies involves lightweighting of packaging. Not only does a lighter package require less material, but it costs less to manufacture and transport. You only need to look at the ubiquitous PET polyester water bottle to see the effect “thin-walling” has had in recent years. In beauty products, however, a thin, flimsy package will inevitably reduce the perceived value of the product. That’s why there is such keen interest in the newest chemical foaming agents (CFAs) available for use in injection molded, thermoformed and blow molded plastics components. Finer and more durable foam-cell structures now make it possible to achieve resin-use reductions of up to 25% without a significant loss in appearance or mechanical properties.

Foaming is not new. It has been used extensively in electronics housings, home and garden furniture, luggage and, more recently, in automotive interior parts to reduce weight and raw material use. Added to plastics during processing, foaming agents such as Clariant’s Hydrocerol masterbatches decompose to produce small quantities of carbon dioxide to form microscopic bubbles in the polymer matrix. The gas displaces the polymer so that it takes less plastic to make a bottle, closure or other packaging component.

Until recently, acceptance of foaming used to create bottles and similar components for personal care products has been limited by a relatively coarse and nonuniform cell structure that impacted appearance and mechanical strength, especially in thinner wall sections. Advances in foaming technology are now making it possible to achieve a highly uniform structure of bubbles as small as 50–100 microns in diameter—even smaller than the period at the end of this sentence. This compares very favorably to the 400 microns typical of first-generation foams and even the 200 microns, which was considered “fine” until recently. It means there is virtually no appearance or performance difference between structures produced with a CFA versus those made without one. Yet the benefits of reduced part weight and lower production costs are undeniable. Material-use reductions of 7% are common in injection molding, and some converters have reported savings of 25% in certain extrusion applications. At the same time, the CFA plasticizes the resin in the processing machine, so less heat needs to be added to melt it (energy savings); and since less heat has to be removed during cooling, cycle times are also reduced by 10 to 15%.

Even relatively small reductions in material consumption and cycle time can be very important. In fact, when millions of pounds of plastic material are processed in the course of a year, it is very easy to save hundreds of thousands of dollars. Although actual results can vary, internal trials at Clariant showed, for a typical 20 gram HDPE bottle, a weight reduction of 10%. Applying this to five million pounds of parts would generate a net raw material savings of more than $300,000. On top of this, processing-cost savings of the same order of magnitude are made possible by substantial reductions in cycle time.

The increased productivity and reduced material and energy consumption increase the sustainability credentials of the packaging in a documented manner. Less tangible, but no less important, are the benefits that arise from reducing shipping weight for both raw materials and finished products.

How Do You Want to Be Green

Foaming is a technology that can be applied to any material from conventional petroleum-based polymers to natural and biodegradable resins such as polylactic acid (PLA) and even the newest bioidentical materials. These latter polymers are made from renewable sources such as sugar and starch but have identical properties to the fossil-based materials (polyethylene, for example), except for the age of the carbon. Indeed, they are increasingly preferred over other biopolymers because they fit so well into the existing plastics processes, including recycling. PLA and other biopolymers don’t necessarily need to be recycled since they are compostable. However, one problem they pose is that easily recycled plastics such as PET can be rendered useless if contaminated by even a small quantity of PLA.

Nevertheless, PLA and related biopolymers have the advantage of compostability and biodegradability when they are properly handled. That last phrase is key, however. Most landfills actually prevent degradation and so, unless these biopolymers are processed in an industrial composting plant, like some in Europe, they are actually less attractive to companies like Procter & Gamble or Unilever seeking to reduce or eliminate waste sent to landfills. In addition, although there have been significant advances in the formulation of biopolymers, and additives are available to help build melt strength for easier processing, these materials remain expensive, difficult to handle and challenging to color.

Conventional synthetic colorants are readily available, and many have been formulated for use in biopolymers, but while the matrix resin may be compostable or biodegradable, the colorants and additives usually are not. All-natural alternatives are available but limited in number, expensive and not very process- or light-stable. Fortunately, a third choice has recently become available as lines of compostable color and additive masterbatches. While they incorporate conventional (non-natural) additives and pigments in a biopolymer carrier resin, the types and amounts are strictly limited. Testing of the ingredients of Clariant’s offering, for example (completed in the independent laboratories of OWS— NV a global independent provider of inspection, monitoring, analysis, testing and certification services based in Belgium), determined that the materials can comply with EN 13432:2000—the widely recognized standard for heavy-metal content and plant toxicity.

And look for the “OK compost” certification issued by AIB Vinçotte International (Belgium). Any product featuring the “OK compost” logo can be assumed to comply with the requirements of the EU Packaging Directive (94/62/EEC), which seeks to limit packaging waste.

So now beauty brand owners have new options in plastics and new opportunities: working with suppliers to go all the way to the most natural solutions based on raw materials directly derived from nature; choosing bioidentical materials made from renewable resources but otherwise very similar in character to oil-based polymers; or using conventional resins to take advantage of increased levels of recycling. And whatever route chosen, cuts can be made in material use, package weight and energy use through advanced foaming technology.

Consumer goods companies are well on the way toward sustainability. Now the question becomes just how green they want to be or, more accurately, how they want to be green. Today, plastics technology gives them more options than ever.

Chris Pandis is the global head of packaging for Clariant Masterbatches, whose products are marketed under a number of global brand names—including Omnicolor universal color masterbatches.;