Varioustrends and requirements are currently transforming the packaging market:renewable raw materials, reducing the amount of packaging material, cutting CO2emissions, monolayer packaging, recyclability, repulpability andbiodegradability – to name a few. Theoverriding and most urgent trend in packaging is sustainability. That hasresulted in the development of packaging concepts centred on sustainability forvarious types of products. In the dry pet food market, however, conventionalpaper packaging is considered problematic because it uses halogenatedfluoropolymers to create a barrier to fat. In this sector, applying a very thinlayer of carefully selected plastics may make more sense and be moresustainable.
The pet food market is booming
In industrialized countries, the pet foodmarket has grown rapidly in recent years – in parallel with the number of pets.The restrictions imposed during the pandemic doubtless contributed to theincreased interest in pets, which has also led to a boom in pet food. In fact,the number of packaging units sold is growing faster for dog and cat food thanfor any other type of fast moving consumer goods (FMCG): the compound annualgrowth rate (CAGR) was around 25 percent between 2015 and 2020.
Paperis regarded as sustainable
Consumers generally regard paper-basedpackaging as more sustainable. That applies to food for human consumption aswell as pet food. However, it is vital to ensure that innovative packagingsolutions continue to meet the full range of functional requirements for foodor - in this case – pet food packaging. That is an inherent challenge forpaper-based packaging because a reliable barrier to the fat content of pet foodis essential. For example, cat food generally has a 10 percent fat contentwhile the fat content of dog food is typically up to 20 percent.
Fluorinatedhydrocarbons are problematic
In conventional paper-based packaging, theessential greaseproof barrier is normally achieved with the aid of veryproblematic substances: fluorinated hydrocarbons. Halogenated polymers such asfluoropolymers are highly controversial because of their potential harmfuleffect on the human – and animal –- organism. Moreover, pet food packagingcontaining fluoropolymers is extremely difficult to recycle. New, moresustainable alternatives to the common packaging types used at present need toensure a similar barrier to aroma, odour and grease.
Intelligentnew packaging concepts
The four paper-based packaging innovationspresented here meet these requirements because their barrier properties arebased on Kuraray’s future-oriented polymers. These packaging solutions, some ofwhich are already in commercial use, are ideal replacements for paper andcardboard-based packaging with greaseproof properties based on fluoropolymers.They combine sustainability with functionality.
1.EXCEVAL-coated paper bags
Example of aconceptual structure for such packaging:
Paper / moisturebarrier coating / EXCEVAL coating / heat-sealable coating
This type of paper-based packaging isalready in commercial use in the food sector. A thin, water-soluble EXCEVALcoating acts as an oxygen and aroma barrier. EXCEVAL is a halogen-free,hydrophobically modified polyvinyl alcohol (PVOH) from Kuraray. It has beenspecifically developed to ensure that it is resistant to water, oil and grease.EXCEVAL can be applied to paper using conventional coating equipment such asrotogravure coaters and rod coaters. Dispersions of polyolefin or other polymers are used as a heat-sealablecoating on the inside of the packaging. The big advantage of these structuresis that they can be repulped without problem in standard paper mills. Repulpingis a technology approach that has been established in the paper industry for manyyears. However, it cannot be used for fluoropolymers because they are notsoluble in water.
2. Paper-based pouches with a vacuum metallized layerof EVAL and BOPP
Thispackaging concept is based on the following conceptual structure:
Paper / vacuum metallized EVAL EVOH BOPP / laminated castpolypropylene
Kuraray’s ethylene vinyl alcohol copolymers(EVOH) are marketed as EVAL. A film made from EVAL EVOH and biaxially-orientedpolypropylene (BOPP) is metallized under vacuum with a thin layer of aluminium,creating a barrier to aroma, oxygen, light and moisture. A simple castpolypropylene foil is laminated onto the inside of the pouch to act as thesealing layer. A tenter frame is used for coextrusion of the BOPP and EVOH forthe outer layer. This packaging concept avoids the use of a far greater amountof aluminium in the form of aluminium foil. Nevertheless, EVAL EVOH provides anexcellent substrate for vapour deposition of aluminium as well as an extremelyreliable oxygen and aroma barrier. The packaging therefore prevents oxidationof the fats contained in dry pet food. The vacuum metallized layer is a verygood light barrier and preserves the vitamin C in the pet food. This packagingconcept uses the smallest possible amount of plastic and also optimizes therepulpability of the paper fibres because they can easily be separated from thesmall amount of polymers in the washing-step system. The reduction in theamount of aluminium deposited also makes the polymers used in this paper packaging recyclable.
3.Paper-based pouches with a metallized film layer of EVAL and MDO-PE
Thispackaging concept is based on the following conceptual structure:
Paper / vacuum metallizedEVAL EVOH MDO-PE / CPE
This paper packaging is based on the sameprinciple as the previous example. However, in this case, the ethylene vinylalcohol copolymer (EVOH) is combined with polyethylene instead ofpolypropylene. The inner sealing layer is made of polyethylene and the vacuummetallized film and EVAL EVOH are deposited on machine-direction orientedpolyethylene (MDO-PE). Thanks to the tremendous technological advances thatmachine manufacturers have made in production equipment for multilayer film inrecent years, multilayer films with MDO-PE have become an attractivealternative. Using MDO technology, both cast and blown co-extruded films can beuniaxially oriented to achieve better properties. Thispackaging concept also prevents oxidation of fat and preserves the vitamin C inpet food. The packaging does not contain any aluminium foil or BOPET. Moreoverit uses the smallest possible amount of polymer and allows problem-freerepulping of paper fibres.
4. Repulpable paper packaging with PLANTIC biopolymer
Thispackaging concept is based on the following conceptual structure:
Paper / PLANTIC film / sealing layer made of e.g. PE, PBSor PBAT
This paper packaging is already usedcommercially for food. PLANTIC film is laminated onto the inner side of thepaper. Kuraray produces PLANTIC biopolymer from renewable raw materials. It ismade from thermoplastic starch and is biodegradable and compostable (home andindustrial composting). Due to its high gas barrier properties, this biopolymercan be used in packaging that preserves aroma and effectively keeps out oxygen.In this packaging concept, an inner sealing layer - polyethylene, polybutylene succinate or polybutylene adipateterephthalate – is applied to thePLANTIC film and also acts as a moisture barrier. This production technologiesused for this type of packaging are extrusion coating, lamination and extrusionlamination. The inner sealing layer and adhesive can easily be separated fromthe paper in the repulping process. Moreover, thanks to this biopolymer, therepulping yield is higher than e.g. a conventional PE layer because the fibresdo not penetrate the PLANTIC film. Consequently, all of the paper fibres can berepulped without difficulty.
Consumersand brand owners driving the trend
Greater sustainability and circularity arean urgent issue for the whole of society and are being driven forward bylegislators and consumers as well as brand owners and manufacturers. Theobjective is to find circular packaging solutions. Several major players in thefood sector, from Danone and Mondelez to Nestlé and Unilever, have alreadypublished voluntary commitments or pledges. There is still plenty of scope toimprove the sustainability of packaging for dry pet food. Intelligent use ofmodern polymers can help give popular paper-based packaging the necessary functionality –without compromising on sustainability.
Learnmore about the wide range ofhigh-performance materials to make packaging more sustainable and functional.
About the author:
Dr. Bettina Plaumann studied pharmacy andsubsequently held various positions in marketing communications in thepharmaceutical/chemical sector before joining Kuraray as Head of KEGCommunications & Marketing in 2015. Since 2020 she has led the Kuraray SegmentMarketing Team Paper & Packaging.
