According to the European Chemical Industry Commission (Cefic), only 15% of the plastic waste collected in the EU has returned to the EU market.
Due to the lack of process and food safety considerations, most non PET plastic food packaging can not be recycled for new food packaging. Therefore, it is usually used outside food packaging, such as construction and agriculture.
Currently, only 10% of recycled polymers reach food grade, most of which are polyethylene terephthalate (PET) (leardini et al 2021). Plastic recycling is mainly carried out through physical recycling: the cleaned and classified plastic waste is remelted and processed into new food packaging. However, in the process of physical recycling, there may be risk factors of contaminated recycled raw materials entering recycled plastics and polluting food. In order to prevent such packaging materials from entering the market, the European Union and the United States have enacted several laws on food contact materials (FCMs), including plastics and recycled plastics (de tandt et al. 2021). Materials and articles in contact with food, when made of recycled plastics in whole or in part, must be subject to the safety assessment of the European Food Safety Administration (EFSA) and the authorization of the European Commission. RPET resin is approved by FDA for food contact, while China does not allow the use of recycled plastics in food packaging.
At present, in addition to the mainstream food grade recycled PET in the market, a small amount of RPP (Packaging Europe 2021, SABIC 2020) regenerated by chemical recovery process is also entering the European market. In the United States, the U.S. Food and Drug Administration (FDA) has also approved Recycled HDPE for food contact item by item for more than 20 years (custom pack 2018). Similarly, in the UK, HDPE recovered from milk bottles can also be used to produce new milk bottles (Ellis 2019).
Recycled polypropylene for food packaging
Swiss dairy company Emmi is working with Borealis and Greiner packaging to produce Emmi coffee cups made of chemically recycled polypropylene. The regenerated polypropylene technology is still in its infancy, so the output of chemically recovered polypropylene is limited. Emmi obtained some recycled polypropylene through an early agreement with the development company. In the future, the content of recycled plastics in Emmi's latte cup will further increase according to the production of appropriate materials.
The chemically recycled materials used in Emmi latte cup fully comply with ISCC (International Sustainable Development and carbon certification) standards on the basis of mass balance. Since recycled polypropylene is recycled by chemical recycling process, it can be used as food contact materials.
Mars food has established a similar cooperation relationship with SABIC to provide chemically recycled recycled polypropylene for Mars pet food packaging, in which the PP film structure is provided by Huhtamaki Pule.
At present, multilayer food packaging composed of different plastic polymers or different materials is hardly recycled because these layers are difficult to separate. As for paper-based composite packaging, only the paperboard part can be recycled in the existing recycling process, but according to the regulations, the recycled paper fiber cannot come into contact with food (geuke 2021). Recycled cardboard coated with a proven barrier material (Virtanen 2022) can be used for food packaging.
At present, new film coating processes for plastic and aluminum foil in paperboard and paper food packaging, as well as chemical recovery processes for mixed plastics, are being developed. In this way, when the material is completely depolymerized, the chemically recovered polymer can be used as food contact material (European Commission 2021).
Classification and recycling of post consumer packaging
Used packaging, usually contaminated waste, contains different types. It includes various types of materials (such as multi-layer packaging, mixtures and composites), which vary greatly in shape, color and size. In order to ensure consistent quality, the regeneration treatment center sets quality standards for its raw materials and is usually equipped with sorting lines to sort out impurities from waste raw materials. With the development of digitization and automation, sorting technology has made significant progress in the past decade, and its recognition ability and sorting speed have been improved. With changes in packaging design (such as adding optical tracking marks, avoiding multiple materials and dark materials) and the application of new sensors, automatic sorting lines can better distinguish different polymers. At present, classification is usually completed by near infrared (NIR) technology, while new technological innovations, such as hyperspectral camera, can recognize and classify plastics of various colors. In packaging design, digital watermarking is developing rapidly.
HolyGrail 2.0 project is a well-known development project, which has entered the demonstration stage in a material recycling facility in Copenhagen, Denmark. The watermark covering the surface of consumer goods packaging contains a variety of information, such as packaging type, material and purpose. The digital watermark can be decoded by scanning the used packaging with a high-resolution camera on the sorting line (Staub 2021).