Paper packaging is becoming more and more popular, but if you take a closer look most of these packaging solutions come with a thin layer of plastics. With its extrusion coating lines, SML offers an established technology for the extrusion of ultra-thin coatings for paper packaging in compliance with EU and national recycling regulations.
In order to raise recyclability, legislation in many countries now aims to avoid packaging solutions based on a mix of different raw materials. There is a need for new packaging products such as mono-material plastic packaging or paper packaging with extended functionalities.
Improving the properties of paper packaging
Coating can significantly improve the properties of paper packaging. This is especially true when it comes to protection from grease and moisture, printability and sealability. “Faced with the new EU regulations, the main challenge is that the plastic content in paper packaging may only make up a fraction of the total packaging to be classed as recyclable paper packaging. The plastic content shall be less than five per cent,” explains Johannes Danter, Product Manager at SML.
SML extrusion coating and laminating lines, like the FlexPack series, are highly suited to the production of extrusion-coated paper with the lowest coating weights. “Our lines manufacture coatings with a grammage of less than 4g/m², which is, in most cases, absolutely sufficient to achieve the five-percent-target for paper recycling,” Johannes Danter states.
For the successful production of coated paper packaging material with a low proportion of plastic, the following key criteria are decisive:
- A high paper quality with very few impurities
- A perfectly pre-treated paper surface – inline either with flame or corona treatment
- A high melt quality. In its coating and laminating lines, SML uses well-proven high-performance barrier screws to generate melt with a maximum homogeneity.
- An extrusion die with automatic bolt adjustment and an EBR deckling system for maximum flatness and minimum coating weights.
- Ozone treatment as an optional tool to increase adhesion by accelerating the oxidation rate for PE at higher line speeds.
Easily upgradeable
For decades SML has continued to further develop coating and laminating lines for multiple purposes. “The technology, the processes and the systems to manufacture coated paper packaging with a minimum share of plastic is all but new to us. Most SML FlexPack lines, that were manufactured for the food industry, are either ready to produce coated paper or can very easily be upgraded with minor adaptions,” Johannes Danter explains. In addition to “standard” paper coating based on fossil or bio-based polyethylene, paper-based packaging with a barrier layer that includes EVOH can also be manufactured on SML’s lines for coating and lamination.