Flexible packaging A flexible landscape
other items the reverse is true. It is about adding barriers.
T
By Tom Kerchiss, chairman, RK Print Coat Instruments Ltd senescence and extend the shelf life of a product, for example: salad bags and fresh fruit. Providing a barrier within the pack or within the fi lmic or other structure can be useful for preserving a desirable sensory property.
o succeed, whether in life in general or in business, we all strive to overcome barriers, but when it comes to fl exible packaging for food and countless
Some barrier properties are easier to obtain than others. Obtaining a good moisture barrier may be relatively easy, obtaining a barrier to gases may be more diffi cult.
Exposure to oxygen may result in oxidation,
aff ecting the taste and appearance of some foods. For example, red meat becomes grey and fats and oils become rancid. In some cases, the nutritional value of a food can be compromised. The presence of oxygen and nitrogen through nicks and pinholes encourages microbial growth and other spoilers. Apart from the risk to health inadequate barrier protection will damage the brand.
Other barrier critical properties that may be required for the fl exible packaging, particularly onto fi lms and papers include water vapour protection, safe sealing, peel-ability, air tightness, light protection, grease proofi ng, humidity control and heat resistance etc. This list is by no means exhaustive.
Barriers are not always put in place to prevent contaminants from outside getting in. Sometimes a barrier needs to be in place to maintain a balance of gases within the pack to delay cellular
Barriers when needed must be in place to contain and hold fast volatile compounds associated with aroma and fl avour. Stand up pouches (SUP) of coff ee and tea remain fl avourful and full of aroma until opened.
Environmental and cost containment strategies must be in place and in an age where product appearance builds brand image, materials must be readily printable and convertible. Coatings, including surface coatings deliver aesthetic and performance benefi ts to fl exible food and beverage packaging and to other product categories as well.
Producers of packaging for medical devices and disposables must deliver a product that is regulatory and performance compliant; communicates eff ectively and protects the item from product containment and performance compromisers such as the ingress/egress of gases, liquids, temperature fl uctuation and light, etc. Flexible pouches, bags and other devices are favoured for many medical associated applications, they are of low weight, store easily and can be provided with the appropriate handle and grip.
A popular method of coating is direct, reverse
or off set-gravure. Gravure is suitable for a wide range of viscosities. RK Print Coat Instruments especially favour reverse gravure, a selectable option for the VCML pilot coater and bespoke VCM.
Reverse gravure with its large wet coat range
off ers key benefi ts such as uniformity and freedom from pinholes. Absence of pinholes is vital as pinholes will impact on the eff ectiveness of any barrier that has been put in place. Reverse gravure has the capability of applying low and high coat weights by changing the anilox roll. RK have been engaged in the design,
confi guration and manufacture of VCML pilot coating, printing and laminating machines for many converters, material and consumable suppliers and others involved with fl exible packaging. Quite a few are turning to water- based coatings with lower solids content for environmental and sustainability requirements. Some modifi cation to existing processing machines such as coaters is needed. A good number of VCML pilot coaters supplied now incorporate three drying tunnels to ensure optimal drying effi ciency.
Over time packaging materials have been developed, refi ned and modifi ed and even cast aside in order to meet the continuously evolving demands of brand owners, print/packaging buyers, environmentalists and climate changing pundits and most importantly, the consumer. Replacing many multi-web structures with mono- materials; the development of eco acceptable chemistries and bio-based materials (even inks from algae) and the recyclability of polyolefi n, PE and PP sets the stage for future growth in fl exible packaging. Noted areas for growth include e-commerce and lifestyle. Coating is a crucial process in fl exible packaging fi lms and papers. Coatings improve the aesthetic appeal and functionality of a pack. Coatings include primers, barrier coatings, overprint varnishes, heat seal, inks, adhesives and many others.
In the replacement of fossil fuel derivative materials and others that may prove unsuitable for an application, products, materials and components need to be trialled, replicating the realities of real-world processing. Pilot coating systems that off er short run capability and selectable coating applicator technology have a role to play in ensuring profi tability objectives are met and products run are viable and reject-free.
16
July/August 2026
www.convertermag.com
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