When it comes to packaging and environmental awareness, two important questions to ask are, “What types of packaging are considered sustainable?” and, “How can packaging be made more sustainable?”
Plastic is an easy sustainability target because it takes a long time to degrade, which means it sits in landfills for hundreds of years if thrown away. But, if recycled, plastic becomes less problematic—although some types of plastic can be difficult to recycle.
Excess or unnecessary packaging is the first level of unsustainable packaging. After that, packaging that cannot be easily recycled is problematic (i.e., mixed materials that can’t be separated, such as snack bags, Styrofoam cups, plastic-lined packaging like lined cups and wrappers).
To truly understand what type of packaging is more sustainable, a full cradle-to-cradle analysis would be needed. It would have to consider such factors as the energy used to make and recycle the material, the amount of space the packaging takes up and the relative weight of the different packs—and therefore the transportation costs, how much material is used in the different formats, and more.
What about biodegradable materials? They will just degrade in the ground and go back to soil, right? Well, only under certain conditions, which typically means industrial composting. There are only limited industrial composting facilities in many countries currently.
Factoring in the variety of sustainability issues, many brands have a desire to replace plastic or plastic-lined packaging with paper-based packaging that can be more easily recycled.
Desirable Barrier Properties
The challenge with paper-based packaging is that it doesn’t have the same barrier properties as plastic (to water, moisture, grease, gas, odor), so it often needs to be treated with a barrier coating to improve performance. A barrier coating is an additional layer applied as a liquid coating onto the substrate to bring extra functionality. The goal is to enable the paper to behave largely in the same way as a plastic package and remain functional in the application where used.
Without a barrier treatment, a paper coffee cup would quickly leak hot coffee; packaged snacks would lose their crunch as moisture penetrates through the packaging; fast food trays would absorb grease that would spread onto people’s hands or surfaces; sauces would leak from pouches; or food would spoil quickly with oxygen penetration. Not all packages require a high level of barrier, and paper cannot replace plastic in all applications. But, to replace many of the applications where plastic is used with a paper-based alternative, the properties of the paper can be boosted with barrier coatings.
While the concept is strong and intentions good, another concern is that the most barriers used today to make paper-based packaging behave more like plastic, rendering the paper unable to be recycled.
A More Sustainable Barrier Solution
Water-borne polymeric coatings can help overcome that challenge. They can successfully deliver some of the desired barrier properties while still allowing the paper to remain repulpable, leading to reduced plastic usage and increased recyclability.
That’s not to say there aren’t special considerations when using water-borne polymeric coatings for this purpose. Coating application can be a critical step in achieving the necessary performance. The coating also needs to deliver the functionality required for specific applications beyond barrier properties (i.e., heat sealability, printability, food-contact compliance), and the coated substrate needs to be processable with existing packaging manufacturing equipment. For example, coated cup-stock (the board used to produce paper coffee cups) needs to be sealable at the same speeds and temperatures used with plastic-lined cups so that cup production efficiencies are largely maintained.
The upfront cost of the coating can be more expensive than the plastic it is replacing because polyethylene film is a commodity material, but there are many other considerations to take into account when analyzing the total cost: relative overall production costs, the ability to recycle industrial waste, the ability to recycle post-consumer waste, avoidance of packaging taxes and the boost to brand image and the potential resulting increase in sales from this boost for a company that implements sustainable packaging solutions.
Lubrizol’s Water-Borne Experience
Lubrizol has extensive experience developing formulations based on well-established water-borne polymeric dispersions. This experience and know how is proving invaluable in overcoming challenges of water-borne polymeric coatings as a barrier treatment, including the ability to design in additional functionalities that meet customer requirements and to tweak the product to optimize its design for use in production.
This water-borne coatings approach means that waste packaging, either from the manufacturing process or after consumers have disposed of it, can be recycled in the standard paper-recycling stream and repulped before being used to produce recycled paper for further use. This saves costs in manufacturing and reduces the amount of material that goes to landfills, while creating future value in recycled paper products and sending a good sustainability message to a brand’s customers.
Contact us to learn more about how Lubrizol can help you create more sustainable packaging by replacing plastic through the use of water-borne coatings for paper packaging.
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