Milliken: NX™ UltraClear Polypropylene for thermoformed food packaging

Milliken's pioneering Millad® NX™ 8000 clarifying agent has removed the transparency obstacle for PP (polypropylene), enabling PP to now offer an all-round solution to the European food industry's criteria for high-quality packaging. Considering the necessary requirements for today's applications - lightweight; stiffness & impact strength; transparency; sealing effectiveness; hot fill, retort and microwave ability – NX UltraClear PP proves itself to be an overall attractive alternative to other glass clear materials like A-PET and PS, the market's current preferred materials, for many sheet extruded / thermoformed applications. NX UltraClear PP also offers obvious advantages when it comes to sustainability and recyclability.

Glass-clear transparency

The days of thermoformed PP applications with a milky appearance seem to have gone. For thermoforming and sheet packaging, NX UltraClear PP clarified with Millad NX 8000 sets a new clarity standard for PP that is comparable to glass-clear materials and which enables PP to be made as clear as A-PET and PS. Use of Millad NX 8000 can give PP applications a glossier aspect than normally possible with standard nucleated PP.

Lightweight + productivity gains

NX UltraClear PP has a significantly lower density than other plastic material options, reducing the weight of a thermoformed part. PP's density of 0,9kg/m³compared to PET's density of 1,37kg/m³ simply lets converters produce more trays per kg. If the potential to use less material and reduce Eco-Tax contributions is considered, NX UltraClear PP proves itself to be a sustainable, cost-saving alternative solution for food packaging.

Stiffness & impact strength

For NX UltraClear PP to achieve the same stiffness as A-PET, typically the PP sheet is made 15 – 20% thicker compared to the virgin A-PET sheet. However, when opting for a ribbed or improved design, often there is no need for thicker walls with NX UltraClear PP. The lower density of PP results in final UltraClear PP applications with significantly lighter weight than corresponding PET applications yet with equal stiffness.

Sealing in freshness

PP is known to be easy to seal and very robust. Importantly, standard PP sealant films still offer good sealing performance despite any residue on tray edges and exteriors caused during filling. A mono-material PP tray & PP film solution offers the advantage of a 100% recyclable system which does not require the use of an adhesive. For the best seal strength, PP trays sealed with polyolefin films is recommended.

Hot filling, retort & microwave ability

NX UltraClear PP is a good choice for any thermoformed cup or tray application where higher temperatures are concerned. Its excellent heat resistance makes it suitable for hot fill and for microwaves. These benefits, plus good cold temperature performance, fulfill the "fridge to microwave" concept for food packaging.

Recycling & sustainability

PP offers a circular economy which results in end-of-life solutions for applications. There is an existing market for recycled PP (rPP) in a wide range of products such as caps and closures, buckets, automotive applications, pipes, pallets and garden furniture. As a material, PP consumes the least amount of energy during production and produces the lowest carbon dioxide emissions. It has a lower density which means that switching to PP also reduces the absolute amount of waste. Importantly, it is widely accepted that thermoformed NX UltraClear PP applications are straightforward to recycle because it is a monomaterial concept.

Summing up

As the prodicer stresses, with NX UltraClear PP, high clarity comes together with significant performance and sustainability benefits, to create an attractive alternative for many sheet extruded / thermoformed food packaging applications. This new choice for converters and brand owners is ready to be explored.