Just as skin is the largest organ in the human body, providing a barrier against all manner of foreign pollutants, “skin” for manmade products is also essential. Moisture, oxygen, dust, ultraviolet light—these invaders can corrode everything from semiconductors to vitamins. In response, industrial players have invented coating technology like atomic layer deposition (ALD). ALD sees an ultra-thin layer of film applied to the surface of an object. It is extremely uniform but has typically been limited in scale, due to manufacturing and other technical constraints.
This is changing, in part due to efforts by innovators like Kalpana. Kalpana’s technology could see ALD spread from its usual sectors of advanced electronics and solar cells to a much broader ecosystem. This includes makers of flexible packaging.
In this interview, Graham Carey explains the appeal of Kalpana’s approach and its relevance to packaging.
Why are packaging producers interested in this new coating technology?
Retailers and brand owners need packaging that allow consumers to enjoy safe, affordable, shelf-stable food and drink. Expanding this market while driving circularity is a huge challenge. Usually, packaging producers rely on a complicated laminated “stack” of different materials; this may include a cellulosic fiber (paper) layer, an aluminum layer and multiple layers of plastic. These stacks provide a high degree of protection but are difficult to recycle, since they include so many different types of material.
New packaging formulas are both easier on the climate and more circular, generally relying more on cellulosic fibers. If the fiber is procured from a sustainable source, it can be more environmentally friendly than aluminum or plastic. Many packaging producers that use fiber are thus trying to increase the share of that fiber that’s been certified by the Forest Stewardship Council, a leading standards body. This makes it a clean, green alternative to business as usual.
Using only a single layer also reduces complexity and simplifies end-of-life, driving recycling and closed-loop packaging solutions. But while fiber provides sustainability benefits over alternatives, it lacks barrier properties. This is where coatings come in. A coating which is light, thin, recyclable, easy to apply in large quantities and provides a high degree of protection can help popularize more sustainable packaging materials.
Why is ALD preferrable to alternative barrier methods?
Leading barrier layer technologies include:
- Metal foils: these offer excellent barrier properties but, as mentioned above, are typically one layer of a complex and non-recyclable stack of packaging. They’re commonly used in high-barrier applications where transparency is not required, such as food packaging, but are limited in other applications.
- Polymer films: these are a kind of plastic coating that can provide reasonable barrier properties and flexibility but may not be optimally effective against moisture and oxygen. Impact on recyclability varies.
- Vacuum-deposited coatings: as the name suggests, these coatings are applied in a vacuum to prevent contamination. They offer strong protection against gases and moisture but can be relatively costly and/or impede recycling.
There are drawbacks and benefits to each of these, but in general we believe that ALD, if done right, can strike the right balance of barrier efficacy, cost-sensitivity and environmental performance. In particular, a subset of ALD known as spatial ALD (s-ALD) is very promising. S-ALD tweaks traditional ALD methods to allow coatings to be applied faster and over a much larger area. Until recently, however, it was hard to apply s-ALD coatings evenly across an entire surface, especially at the high speeds and low costs desired in certain industrial applications. Solving this processing challenge is Kalpana’s key innovation. We believe that trailblazers like Kalpana will help s-ALD can hit the sweet spot that packaging producers are looking for.
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