Sustainable Converting - A Trialing Process
By Tom Kerchiss, RK Print Coat Instruments
Environmental compliance, statements of intent such as the aim to recycle and/or reuse and to manufacture, print and convert from sustainable resources are no longer phrases banded about to mollify environmentalist, the media and concerned consumers. Every industrial process is too some extent under the spotlight; industrialists of most persuasions recognise the need to develop new processing strategies and use materials that are (where possible) carbon neutral and at the end of life cycle can be safely disposed of
Fuelled by anti-plastic sentiment and the fact that packaging is ever present, and highly visible in our day to day lives, the industry, the processes and the materials and consumables are subject to more than its fair share of criticism. Package printers, converters, producers of paper, film, foil and other materials; ink, adhesive, coating formulators have made notable progress over the past decades on the environmental front and much is now being done in working towards sustainability targets.
What should be acknowledged is that much of what is being said and done in the name of sustainability is sometimes based on perception and not on fact. The media often gets it wrong and industry is often slow to publicise its successes. Products and processes need to be trialled and performance, health and safety parameters and disposal properties assessed over the long term. It would be counterproductive and harmful to tout a material, a consumable or process and bring it to market only to find out that in the long term the item is more harmful and less sustainable than the one it has replaced.
Can the converting, packaging and other processes even achieve sustainability? True sustainability, that is where every material mounted on a web fed converting machine is guaranteed free from additives and chemicals that have some impact on the environment, somewhere along the line is a challenge, at least for the moment.
As it stands it is very easy to define an environmentally and sustainable product or process as one that does not impact on the environment in any way. The problem is that just about everything we do whether as producers or consumers impacts on the environment –and that includes the packaging we produce and throwaway; the products we use to keep our homes clean; the food and medicines that we produce and use as well as the coatings, the paint, etc, that are used to protect our bridges and buildings from environmental damage from rain, storms and from the beating sun, etc.
Using less harmful chemicals and seeking solvent substitutes was the first step that industry took a decade or so ago towards meeting environmental as well as health and safety requirements. Printing and packaging converting had been a high-volume user of ozone depleting and harmful chemicals: cleaning blankets and presses with cleaning agents that contained VOC emitting compounds and relying heavily on solvent inks and other consumables. Many coating and varnishes contained phthalates, heavy metals, VOCs and HAPs. Much has changed, the industry has by and large risen to the challenge, printing and converting is certainly a lot cleaner than it was with the introduction of water-based coatings, inks and adhesives and better support technologies, such as quality control, product development systems. Never the less as scientists develop a better understanding of changes in climate and of the drivers of change, the negative impact of our industrial processes and mode of life it is apparent that there are many areas of print and package production that need attention.
Many of the materials and technologies developed as replacements are certainly less harmful than previous products used to support converting processes but dig deeper and there are additives and components even in consumables such as water-based inks, coatings and even in some paper based materials that may, for some not equate too well with the ethos of sustainability and environmental neutral concepts.
Let’s stay with ink for the moment. Ink performance is, to a large degree, and especially if we consider water based flexo inks incorporate additives in with the ink to optimise specific properties. Ink may incorporate lubricants, surfactants, cross linkers, anti-foam agents, thickening agents, adhesion promoters, oxidising agents and plasticisers.
Common lubricants that have been employed include PP and PE waxes, silicones, fatty acid amides and fluorocarbon waxes such as tetrafluoroethylene. Oxidising agents are useful when very high alkaline resistance is required and plasticizers also help to improve functionality in that they contribute to ink flexibility.
Moving along - what about the substrate itself? Paper and paperboard are regarded as a sustainable substrate, suitable for many applications. But even here things are not always clear cut. Paper may be coated to improve barrier properties with ethyl vinyl alcohol or EVOH. Highly effective EVOH provides protective benefits but it is of a hydrophilic nature so an additional polyolefin coating may be applied to prevent water absorption. While the paper becomes more functional it must be borne in mind that some of the desired objectives such as sustainability, recyclability and bio-degradability can be compromised.
Some of the most interesting product developments is in the area of bioplastics; bio based or plant- based polymers and bio degradable and/or recyclable products, many of which are regarded as being sustainable, non- damaging to the environment and natural. Bioplastics are derived from a renewable biomass such as corn, starch, pea starch and even from milk. With regard to the latter, casein protein from sources such as milk are bound together with clay. Not all bio materials are recyclable but many are including the casein or milk and clay example. Starch based materials are suitable for some applications. Derived from corn and potatoes, they are industrially compostable. Some of the products such as potato/starch over-wrappers could be composted at home by the consumer. Other bio renewables include PLA or poly lactic acid. PLA can be structured for rigid or flexible packaging purposes. Offering good dead fold properties this corn based material is a high clarity material that is suitable for a number of food packaging applications.
Its worth noting that while bio-based materials for instance may sound as though they are an environmentalist dream material, even these have their critics. Some bio-based materials such as native or natural starch products need special pre-processing treatment prior to conversion as they can be toxic. Cassava, a seemingly ideal starch laden plant for example, is extremely toxic. Cassava also depletes soil of potash. Some environmentalists have concerns that thousands of acres often in areas covered with native forests will be given over to growing bio materials for packaging affecting food production, water tables, soil (especially when grown on marginal land) and the web of life. Critics cite the issues surrounding palm oil grown as a mono product and its affects on wildlife and nature in Asia as an example.
In the here and now, material and consumable suppliers and innovators are working with technology suppliers, converters and other supply chain providers to bring on to the market workable and sustainable packaging solutions. Packaged products must be functional and in terms of processing tick all the right boxes, they certainly must be printable and convertible. Inks and substrates must be compatible and perform well over the life time of the product; new materials must not only meet sustainability or other targets the products mounted on and processed through a press or coater, etc, must not disadvantage the processor with regard to commercial viability. Colour communication devices, pilot lab coaters and trialling and product development tools have an important role in ensuring product viability and commercial effectiveness.
RK Print Coat Instruments FlexiProof family of colour communication and proofing devices enable users and producers of flexo inks to ensure consistency of performance; determine printability; trial unfamiliar products; colour match and assess how inks and component ingredients interact with substrates over time. Additive, resin and ink manufacturers are amongst those that use the FlexiProof 100, the FlexiProof UV or FlexiProof LED UV. Other users include printers/converters, plate manufacturers, anilox roll developers, education and research and development establishments, indeed any organisation with an interest in flexography.
Many factors influence material or consumable selection, which is why there is a need for vigorous product development programs and a need to undertake pilot runs and monitor product quality. It is also the case: coating is a particular example where it is not always certain which coating technology is the most appropriate for the task at hand. A degree of experimentation, real world trialling is needed to ensure that product performance is not going to be compromised and that the product can be processed, coated and dried at an acceptable speed with minimal risk of returns and reworking.
The VCML Lab/Pilot Coater enables operatives to print, coat and laminate on all types of flexible substrates. Various coatings including inks, varnishes, adhesives and even paint that involves the use of water-based materials or even solvents can be applied. The VCML Lab/Pilot Coater also offers short run capability and is highly configurable in order that it can meet the specific requirements of today’s highly individualised customer and product dictates. Knife over roll, meter bar, gravure, direct gravure, reverse and offset gravure; flexo; rotary screen; slot die and other technologies are available. Hot air and UV curing as well as infrared; corona treating and ATEX coating zone configurability extend possibilities still further.
RK Print Coat Instruments Ltd
Litlington, Royston, Hertfordshire SG8 0QZ
www.rkprint.com sales@rkprint.com
Source: RK Print Coat Instruments Ltd
