Company insight Recyclable paper coatings Leon Krings, business development manager, Paramelt, examines how functional paper coatings offer recyclable packaging solutions.

oday’s packaging landscape is In contrast to plastic-coated paper, the primary driver in today’s packaging shifting; packaging engineers now waxed paper is inherently biodegradable, environment. Wax-based solutions offer T have to take a much more holistic degrading at about the same rate as leaf a comparative cost basis compared with view by considering sourcing as well as mulch. This is especially beneficial in both plastic films and extrusion coated end-of-life scenarios for the packaging individual confectionery and fast-food papers while providing numerous material, and taking much more wrap applications, where the risk for environmental benefits. responsibility for product stewardship. littering is high. Moreover, appropriate This has created a highly favourable wax-coated paper structures meet the Water-based barrier and environment for paper-based packaging requirements for industrial composting heat seal coatings aligning strongly with documented according to EN 13432. Many papers rely on combinations consumer preferences. Paramelt provides More recent studies have also shown that with plastics, by extrusion coating or functional solutions for paper-based contrary to common wisdom, wax-coated film lamination, for their functionality. flexible packaging based on two key paper is repulpable for use in standard Paramelt’s unique Aquaseal technology platforms of strong current relevance: recycled paper production. Certification provides water-based polyolefin ■■Paraflex: wax-based recyclable testing at CTP France shows that excellent dispersions (PODs) from the same paper coatings. results are achieved, producing paper with polymers used for extrusion and ■■Aquaseal: water-based coating solutions very good strength and visual appearance. film production. based on high solids dispersions of In this way, wax-coated paper can offer In this way, packaging producers can conventional extrusion-grade plastics. a comprehensive solution in all ‘end of life’ achieve the same paper functionality at scenarios, be that energy recovery, littering, lower applied weights, via conventional Both approaches offer significant recycling or composting. printing and coating methods. benefits for designers of paper-based packaging, enabling the creation of high- performance, environmentally responsible “More recent studies have also shown that packaging papers. contrary to common wisdom, wax-coated paper is repulpable for use in standard recycled Vegetable wax-based coatings paper production.” In nature, waxes provide excellent repellency and barrier properties. For example, both mineral waxes such as While this goes partway by addressing the Functionalised paper based on Paraflex paraffin grades as well as ‘waste issue’, mineral waxes do not tackle extrusion or film lamination is difficult Paraflex Nowax organic waxes, based on the renewability of the source material if not impossible to recycle, because the hardened vegetable oils, yield equivalent and reduction in fossil-based carbon use. polymer film cannot be broken down in barriers to polyethylene and provide In order to tackle this aspect, Paramelt the repulping process and is difficult MVTR under tropical conditions has invested significant R&D efforts to to separate causing significant process (38°C/90%RH) of between 150– 200g/m2/ identify and establish sustainably sourced, disruption and losses. day per µm of coating. vegetable-based alternative waxes to close As consumers frequently have difficulty This characteristic alone led to huge the loop in regard to sustainability. in material separation, these structures volumes of wax paper in use providing the Under the brand name Nowax, various nonetheless often find their way into the first flexible packaging material for food vegetable oils and fats are modified and paper stream causing significant down-time preservation. However, the use of wax blended to provide direct countertypes to and loss of efficiency. In contrast, when paper has been reduced to a small number traditional paraffin-based materials. These applied by coating from aqueous dispersion, of niche applications like confectionery Nowax coatings offer equivalent or superior Paramelt is able to formulate Aquaseal- packaging, and cheese and meat performance to mineral-based waxes. By based coatings, providing the same wrappings being largely superseded by using these Nowax materials for the coating functionality which are fully repulpable. plastics. As a result, there is now little of paper, effective packaging structures Extrusion-coated and laminated paper familiarity with wax paper structures. are achieved that contain in excess of provides excellent barrier against water, Nonetheless, wax-coated paper offers 90% renewable, bio-based raw materials. water vapour and grease, as well as heat significant benefits in the context of Of course, cost impact remains an seal functionality. This strong balance of today’s packaging demands leading to important consideration for retailers and properties find application in many renewed activity in this area. brand-owners, although it is less and less market segments such as disposable paper

36 Packaging Today / www.packagingtoday.co.uk Company insight

Schematic representation of permeability as function of coating weight for a specific material Permeability

Coating Extrusion Lamination

10 20 30 Coat Weight (g/m2) Due to consumers’ sustainability concerns, paper-based packaging has come to the industry forefront. Source: Paramelt cups and fast-food containers, portion Packaging specifications are generally recyclability according to EN13430 packs and confectionery wraps. established to control the consistency of Numerous other examples, such as sachets The layer or film thickness is often an existing solution and not always the for condiments, sugar and tea bags, point- selected depending on the barrier functional requirements of the material. of-sale pouches and wrapping sheets, requirements and typically ranges 10–100μ. Many replacement activities have failed barrier sack paper and cheese wrap are However, for heat sealability, a coating since the target specification is defined on now in the market place or well on the way thickness of only a few microns would be a 1:1 transfer of the properties achieved to commercialisation. needed. While seal strength is related to with extruded PE. Of course, the barrier coat weight, it quickly exceeds the inherent performance of a PE-based coating is Exciting possibilities strength of the substrate, especially for directly related to the coating thickness. Vegetable wax-based coatings for paper paper. However, it is technically difficult to A thinner, water-based coating will provide a sustainable barrier solution achieve consistent layer thicknesses below inherently therefore yield a lower overall suitable for use in a wide range of packaging 10–12g/m2 by extrusion coating, so often much thicker coatings are used even where the barrier is not required. This results in “The emergence of novel water-based polyolefin products that are overdesigned in terms dispersions provides exciting new routes of heat seal and barrier performance. to heat seal and barrier functionality for In contrast to PE-coated or laminated flexible packaging.” paper, there is only very limited uptake of water-based heat-sealable barrier coatings for paper and these are mainly based on MVTR but this is frequently sufficient for applications. The waxes themselves are acrylics or PVdC-based emulsions. the target application. based on renewable green carbon and, in Acrylic dispersions offer some barrier, When applied from dispersion, the combination with appropriate base papers, but tend to be highly sensitive to ambient coating microstructure is different to a are fully recyclable and biodegradable. humidity, while heat seal performance is continuous plastic film. By control of The emergence of novel water-based only moderate, especially in regard to formulation, we are able to render the polyolefin dispersions enables exciting hot-tack. PVdC-based systems exhibit coatings largely redispersible in the new routes to heat seal and barrier excellent barrier properties and a level recycling process without negative impact functionality for flexible packaging, of heat sealability, but halogens continue on the barrier or sealing characteristics. enabling drop-in solutions for existing to have a negative environmental image This offers a number of drop-in solutions structures. Because these dispersions linked to potentially hazardous air and for existing paper-based packaging can be applied using conventional coating water emissions. structures, but which are fully repulpable. and printing techniques, much lower In contrast, Aquaseal coatings are based Testing on cup stock board of 250g/m² coating weights can be achieved while the on the same polymers as used by extrusion with 10–12gsm POD coating easily microstructure of the coated layer makes coating and film lamination and therefore disintegrates under typical recycling the functionalised paper readily repulpable offer the same level of barrier performance conditions, giving a fibre yield of >99%. allowing such structures to be directly on a gram-per-gram basis, are resistance to Paper produced from the recovered recycled via existing waste streams. ● moisture, acids and other chemicals as well pulp shows a very good quality and this as providing excellent sealability and hot structure has been verified by CTP For further information tack performance. France as meeting the requirements of www.paramelt.com/packaging

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