Bio Packaging: A Work in Progress
By Tom Kerchiss, RK Print Coat Instruments
At present plastic and plastic packaging is suffering from an image problem (and that is understatement). Wildlife programmes of which there are many currently being shown in the UK and around the world in general showing marine life, birds and mammals caught up in plastic detritus often unable to feed and slowly choking on plastics and other wastes is serving as a wake up call to all of us that waste, including spent packaging needs to be reduced and managed more effectively.
At the moment few people seem to have a good word for plastic packaging, but some would say that its not just plastic packaging. Many consumers think that there is too much packaging in general and that much of it could be done away or at least it could be severely curtailed via legislation and taxation.
For the moment lets stay with plastic. Iceland, a UK food retailer have gone on record pledging that they will eliminate every piece of plastic packaging from their stores within a time frame of five years. Currently they are involved with a supplier in returning to the use of pressed paper egg containers rather than the plastic thermoformed egg boxes currently used.
The publicity generated from this announcement has galvanised rival competitors into action and we can be sure that moves to limit or regulate packaging materials will be forthcoming. Perhaps some form of restrictive and cost associated measures, which was so successful in reducing the demand by consumers for plastic bags at retail checkouts.
The media, TV, newspapers and somewhat belatedly politicians have jumped on the bandwagon to make packaging a hot topic. Certainly the public at large - both young and old think that anything that minimises packaging and the amount that ends up in landfill sites is a good idea. There is a widespread perception amongst media personnel and many consumers that products are over packed. – In reality most packaging and the component associated with it are there for a good reason. After all no manufacturer wants to over engineer a pack or its contents and in doing so add extra production costs. Whether for product protection or to keep an item fresher for longer packaging and the various components are there, despite what many consumers think for a good reason.
Often when consumers, retailers, the media and others talk about plastic films they tend to treat them as being all the same. The reality of course is very different they can be complex or relatively simple, much depends upon product demands. Plastic films are generally sourced from petroleum and its derivatives, though plastic like materials can, and are going to be made increasingly from bio related materials.
First of all lets look at the upside to using traditional petroleum/polymers formulations. Plastic films and composite structures provide many advantages: they enable manufacturers and converters to provide customisable solutions. For instance thinner gauged filmic materials help with regard to cost containment strategies; different multi-layer structures developed using co-extrusion, extrusion lamination, adhesive lamination and coating using product development and quality control devices such as RK Print Coat Instruments pilot coating/print/lamination system, the Rotary Koater or customer bespoke VCM ensure product and commercial viability, providing a product with the desired performance properties, which might include barriers against light, aroma, fats, gases, moisture and other product spoilers.
Other upsides to using conventional plastics include the fact that they can be engineered in rigid and flexible formats; they offer good printability and convertibility, they offer good sealability and due to the fact that in general they are optimised for the various converting processes, and manufactured in large volumes the cost base is now very low. The downside to petroleum derived materials is that the product is fundamentally finite, extraction and processing is far from being benign; increasingly petroleum is becoming more difficult to extract and accidents can have far reaching environmental and political consequences. Disposal and recyclability can be difficult, many materials, notably flexible packaging may take decades or more to degrade when deposited in landfill sites.
Bio-based materials can be an alternative to materials such as petroleum based plastic rigid and filmic materials. Bio-based materials collectively can be defined as materials that are directly or indirectly derived from a renewable and sustainable form of living matter. Many plastic like substances can be made from plant materials such as cellulose and from animal based materials including chitosan, a derivative of crustacean shells and from polymers produced by micro-organisms and bacteria. In fact the range of bio and compostable materials that are potentially available are staggering, development is still in its early days but many products that are likely to come on the market hold out great promise.
One of the most important and exciting benefits associated with bio-based plastics is that unlike conventional plastics is that many of the bio-based materials are biodegradable and/or are compostable when they reach the end of their packaging life cycle. Compostability is particularly important for packaging that has contained food items. Currently much of the packaging that has held food is of a lightweight structure and of a mixed laminate composite structure such as pouches which is often heavily food contaminated and is too costly or too difficult to clean and recycle or renew.
Food packaging must look good in order to attract and influence consumer purchase. Most importantly though the packaging must secure the product and ensure safety and quality. Formulators and packaging technologists must consider the suitability of the polymers in relation to what they are seeking to achieve with the pack, this may include gas and water vapour permeability, anti-fogging capability, printability, thermoforming capability and much more.
For bio-based packaging to become more widely adopted by manufacturers, retailers and consumers it must meet or exceed the performance requirements of existing materials and meet increasingly stringent disposal and/or recyclability targets. This applies not only directly to the substrates involved but also to the inks, coatings and laminates involved in manufacture. Inks and coatings often need to be re-formulated with non-migratory properties and their separation and disposal needs to be factored in during product development. There are bio-plastics and other materials that are currently suitable for food contact applications but with some (not all) there are printability, anti-static, barrier and various behavioural issues still to be overcome. Bio-based filmic materials are currently proving to be successful in the packaging of organic fresh food produce such as fruit and vegetables (but not shrink wrapped items with a high water content such as cucumbers) where bio-based materials have enabled manufactures to make significant material reductions while extending product shelf life and providing for a high degree of cradle to grave compostability.
Amongst the products that have been identified as suitable for compostability using bio-based materials include pasta, rice and pulses, dry goods that are non-sensitive to moisture; fresh fruit and vegetables, already mentioned and products such as confectionery. The latter could provide significant benefits in providing for a cleaner environment. Confectionery packaging is problematic in that although it is very lightweight it is rarely recycled, even when it is quite feasible to do so. Often it is simply discarded to litter the streets. Biodegradable and compostable wrappers would go along way to reducing throwaway litter.
Plastic filmic producers, scientists, formulators and others are becoming ever more proactive in developing products that are biodegradable, compostable; materials, many of which can be recycled and used as an energy source. Product development and quality control equipment and systems are playing a crucial role in resolving product process issues.
Devices such as RK Print Coat Instruments FlexiProof colour communication and proofing systems are enabling users and producers of flexo and UV flexo inks to not only resolve colour matching issues, but to determine performance related printability issues such as gloss, durability, flexibility, scuff and chemical resistance, etc. As the FlexiProof is in effect a scaled down version of a production flexographic press –product trials, the testing of formulations can be undertaken quickly and efficiently without recourse to a production machine, this minimises waste and is a more efficient way of conducting product development. Systems such as the K Printing Proofer can be used for proofing flexo, gravure and gravure-offset inks as well as for carrying out wet or dry laminating sampling. Many other devices are available for carrying out various tasks: one of these is RK’s Control Coater
The Control Coater enables users to quickly produce accurate and repeatable-coated samples that can be used for quality control and presentation purposes for computer colour matching and research and development, etc.
Occupying minimal bench top space the Control Coater offers variable coating speeds of between 2 and 15mpm and the controlled speed and pressure ensure repeatable results. Vacuum, magnetic, heated and glass beds are available, each of which, when added to the base machine, extend application possibilities. In one instance a Control Coater is being used for making gas separation membranes, perforation membranes, lateral flow membranes and reverse osmosis, etc. For this complex application the client needed to produce thicker castings of polymer and therefore needed to order spirally wound casting bars of 200, 300, 400 and 500 microns which were duly supplied.
There are many bio-based materials available; one that we’ve already briefly mentioned and everyone will be familiar with and will single out is cellulose, the main cell wall constituent of plants. Typically associated with paper and board there is some interest in using the separated fibres, which are then processed using small amounts of binders natural and synthetic into cellulose film or cellophane. Cellulose can also be made into cellulose acetate. This is manufactured by cellulose reacting with acetic anhydride; the formulae is precipitated in water, dried and dissolved in acetone prior to being cast as a film, Cellulose based film such as cellophane has high transparency and gloss. In its uncoated form its highly permeable to moisture but is highly resistant to bacteria, aroma and flavour contaminants. Heat resistant and anti-static cellophane has many benefits. Most cellulose based films however are coated, metallised or laminated. Coatings can be synthetic or bio-based.
Source: RK Print Coat Instruments Ltd