The Ministry of Environment, Forest and Climate Change of the Government of India notified the Plastic Waste Management Rules, 2016 (https://bit.ly/2GBYQ7O) vide a notification dated 18 March 2016. Although some government agencies have sent notices for enforcement of these rules from a date later in this year, a Memoranda dated 17 January 2018 from the same Ministry states, ‘Since the committee constituted by the Ministry has yet to finalize its report and submit it to the Ministry, SPCBs/PCCs are advised not to initiate further action against ‘producers’ pursuant to notice issued by them until further orders of the Ministry.’
In the context of the government’s proposed Plastic Waste Management Rules 2016, and Solid Waste Management Rules, 2016, there is much talk about introducing legislation banning the production and use of multi-layered packaging structures – both flexible and rigid – to facilitate the effective recycling of material resources. It is well known that multi-layered structures, particularly those that incorporate ‘incompatible’ substrates (metallized films, papers, aluminum foils, different polymers) are notoriously difficult to recycle. But, is the ban on multi-layered packaging structures a workable solution?
Multi-layered structures could incorporate similar basic materials (like polymers) or dissimilar basic materials (combinations of paper, aluminum foils, metallized films and polymers). Each of these has to be treated differently in order to recycle it or regenerate the basic material inputs that go into the combination. What is required is to be able to separate the constituent plies into individual layers to effectively recycle them into new equivalent applications and not down-cycle them into lower grade applications like cheap moldings that do not really deliver the kind of functional properties that the original input materials did.
What further complicates matters is that the bulk of packaging systems need to be printed or decorated for reasons ranging from communications, branding, aesthetics, differentiation, providing usage instructions to meeting statutory requirements (statutory labeling, price details, manufacturer details, ingredients, trade-marks, safety information and use-by data among others). It is not easy to totally remove the inks, adhesives or coatings used.
Manufacturers of recycled paperboard will testify that residual ink traces (mostly made from mineral oils) make recycled paperboard totally unsuitable for direct food contact applications and there are several historical precedents of safety problems that are still awaiting legal dispensation. Some materials like vinyl polymers (PVC, PvDC) are not possible to recycle anyway when they are combined with non-vinyl polymers because they tend to release chlorine or HCl when melted and this causes all the other materials to degrade besides causing atmospheric pollution.
High-barrier packaging
High-barrier package requirements make it absolutely necessary to use high-barrier materials like aluminum foils or metallized films in flexible packaging. In a country like India where atmospheric and storage conditions in the supply chain are positively hostile (rampant high temperatures and high relative humidity, unhygienic warehousing), one has to willy-nilly use these high-barrier substrates to deliver even a modicum of shelf-life so that consumer packaged goods are distributed, sold and used by consumers before they begin to spoil or deteriorate.
To expect that consumers will buy products unpackaged or loose and store them in high-barrier containers to get the necessary shelf-life is highly impractical. In fact, the bulk of products like processed foods or healthcare and personal care solutions cannot even leave the manufacturers’ premises without packaging to ensure their safety, efficacy or prevention of spoilage. The only alternative to multi-layered flexibles and or rigid containers is to use recyclable high-barrier rigid systems like metal cans, glass bottles or plastic jars which are frightfully expensive, difficult and expensive to store and transport and totally unsuitable for small-dose packages.
Typically, a metal can or glass bottle costs some 4 to 5 times the price of even the most expensive high-barrier pouch or sachet, requires oodles of storage space, costs the earth to transport both empty containers and packed products due to higher container weight and poor cube utilization. Metal and glass containers also incurs losses due to breakage or damage during transportation and distribution.
It is almost impossible to replace multi-layered high-barrier flexible laminates or rigid and semi-rigid plastics from applications that currently use them as this would not only be totally cost-ineffective but also require the use of much more input materials (metals, glass or even single-polymer plastic systems) simply to make them recyclable; this would negate the very basic purpose, which is to conserve resources and make the whole process more sustainable.
The unfortunate and simple truth is that trying to replace an existing system with one that is very cost-ineffective and requires the use of more input material resources is simply not going to work.
Basic concepts behind use of multi-layered structures
It is important to understand the basic concept behind development and use of multi-layered structures and know why they have been instrumental in establishing flexible packaging as the optimum solution in terms of cost, usage of input materials and a convenience to replace traditional rigid packaging systems for almost any packaging application. The whole business of developing lamination technologies to combine discrete layers of different substrates and, indeed, the development of substrates themselves with tailor-makeable functional properties has been solely driven by the need to deliver optimum solutions that are most cost-effective, most light-weight (and,therefore, use the lowest amount of input resources) and most convenient for any application.
The very concept of composite materials or multi-layered structures is based on some of the following truisms:
Different materials deliver different levels of functional properties.
Materials that deliver higher functional properties are more expensive.
Packaging requirements are complex and numerous (like barrier, sealability, product compatibility, strength, high/low transparency, aesthetics, printability, machineability, after-use disposability and others).
No single material is able to cost-effectively deliver all the packaging requirements.
The required bulk or substance needs to be made up using the lowest quantity of higher barrier materials together with the highest quantity of cheap materials like commodity polymers.
The ultimate solution needs to be as light-weight as possible.
The ultimate structure needs to use the lowest amount of input materials.
The ultimate structure needs to use as few plies or constituents as possible (every additional ply requires an additional or more complex laminating operation).
The ultimate structure needs to meet all statutory and consumer and market needs.
The ultimate structure must be convenient to manufacture, convenient to use and consumer friendly.
The solution must be the most sustainable.
Plastics offer some of the best solutions because of their excellent functional properties, high strength-to-weight ratios, low cost per unit area, low specific gravities and suitability to withstand most processing operations, comparatively low melting temperatures (energy requirements, high machine speeds in operations that require conversion and sealability) and ability to be tailored to exact requirements.
Flexible packaging solutions are more suitable than rigid solutions as the latter require a minimum bulk for structural purposes.
Flexible packaging structures can be optimized whereas rigid systems are usually constrained by industry standards. Any flexible structure can be manufactured with minimal and inexpensive machine adjustment. Changes in rigid structures need more expensive initial set-up costs.
Multi-layered structure based flexible solutions have a much lower carbon footprint and are more sustainable in comparison with rigid or semi-rigid systems.
Over time, various constraints like functional properties, processability (sealability, retortability, sterilisability, resistance to irradiation, etc.) and product compatibility have all been overcome by focused technology development on processing or development of tailor-made substrates. This has all gone towards development of more and more effective multi-layered structures in combination with technologies like food processing enabling lamination to reach extremely high levels of sophistication.
More and more laminated and flexible multi-layered structures are breaking into new packaging applications replacing conventional rigid systems and the replacement trend is quite relentless. All this has also led to substantial source and material reduction and more sustainable solutions.
Let us now examine a practical example of replacing multi-layered structures with a single-material solution. Let us assume that we require a sealable medium-to-high barrier (moisture and gas barrier) package. Let us see if a multi-layered solution can be replaced by a single-material solution so that the after-use waste can be easily and effectively recycled. The one material that springs to mind is polypropylene (PP). If we do not want to use a metallized film based laminate, we can use a single layer of PP. However, to get the same level of moisture and gas barrier, we need to use a much higher thickness of PP and we would then need several millimeters of PP instead of operating in the micron range.
This would need mean a fairly stiff and an inconvenient and difficult to handle material, not to mention that the material usage would go up very substantially. We could get everything we need from a laminate of metallized BOPP/LDPE film that would be no more than 40 microns in thickness and weigh no more than 35 to 40 grams per square meter. This would also have a much lower carbon footprint and constitute optimum usage of input material resources. Needless to say, a rigid can or glass bottle would not only use much more materials but also be 4 or 5 times as expensive. Is this a sacrifice anyone would be willing to make just to ensure that the package is totally recyclable?
Conclusion
We have to accept that multi-layered structures and multi-layered flexible laminates are here to stay. They will never be replaced by single-material solutions, even single-material polymers, just for the sake of recyclability. We have to remember that while we are not able to regenerate multi-layered structures into fresh material resources, the initial commitment of material resources is so minimal that the primary decision on what to use is overwhelmingly in favor of multi-layered flexibles comprising different materials.
