CASE STUDY 2: Durable egg box made of PET bottles

The purely Hungarian-owned Jász-Plasztik Kft., founded in 1990, has grown into a giant company employing around 5,000 people. Among the company’s diversified activities, the utilization of plastic waste plays an important role. The company’s goal is to develop its waste utilization activities on its own R&D base, and to be able to test the development results in the context of test plant production. The results can be used directly in manufacturing production and waste recovery activities. Egg boxes are made from 100% recycled PET raw material (labeled and printed) for European markets at the factory in Nagyréde. The egg containers are produced after the cleaning and grinding process of 4 tons of PET bottles per hour. In addition, the company’s plastic recycling repertoire includes LDPE/HDPE film, with a capacity of 1.5 tons per hour (jp.hu 2022). Plastics are processed, among other things, at the company’s sites in Nyíregyháza (Figure 7) and Jászberény. In order to be able to process it again, the generated plastic waste must be brought to a suitable condition from the point of view of production, using different preparation procedures. During the preparation process, the physical properties of waste primarily change (Ronkay et al. 2014). In the case of the company, the raw material is provided from PET bottles that have become waste and are collected selectively.

7. Figura Jász-Plasztik Kft. Nyíregyháza manual (Source: nyiregyhaza.hu 2022)

It is difficult to separate the plastic waste received from the public by material type, as they have a diverse composition, their material composition is often undetectable with the naked eye, and they are contaminated to varying degrees. The separation process is therefore lengthy and can often only be carried out in several steps. If there is a large amount of dust or other dirt on the surface of the plastic waste, it may be necessary to wash and clean it before processing the waste. Mechanical handling processes are usually preceded by manual sorting. This ensures the removal of dirt and metal waste, as well as sorting by color in the case of PET bottles and by material in the case of other plastic waste. Magnetizable metal waste is removed automatically, using a magnetic separator.

The operation of shredding with the help of cutting shear or a grinder is typical for the pretreatment of PET bottles of suitable strength on the sorting belt. PET bottles are thermoplastics; they melt at high temperatures, 160-300^oC, which makes it easier to create the secondary product. Plastic agglomerates of roughly the same size made from PET bottles of a given color are fed into the so-called extruder machine. The plastic waste is fed through the device’s feeding hopper, then passes through the heated cylinder body with the help of a rotating extruder screw, while it melts. The homogeneous molten material is pressed out of the equipment in the form of many parallel threads. These soft fibers are cooled and the solidified thin fibers can then be cut to the same size and appearance (Figure 8) (Ronkay et al. 2014). This is how we finally get regranulates, reinforced with other additives and made more resistant, which are secondary raw materials for the production of plastic products. Egg cartons can be produced from these regranulate “grains” by injection molding. Automatic machines have produced more than 20 million egg cartons made of recycled plastic in the Jász Plasztik factory in Nagyréde, which employs nearly 100 people (Pásztor 2013).

8. Figura Regranulates made from PET bottles (Source: jp.hu 2022)

A high-volume of products can be produced quickly and efficiently with injection molding. The advantage is that while the extruder can only produce a product with an unchanged cross-section in an infinite length, injection molding can produce complex 3D products of any shape, in batch mode, or even completely waste-free. As with the extruder, injection tools are not universal in injection molding, i.e. only one type of product can be produced with one mold (Ronkay et al. 2014).

In today’s unsustainable world, plastic recycling has become an indispensable tool for the circular economy. The circular economy is a sustainable model in which tools and objects that have reached the end of their use are either made suitable for reuse or reprocessed and utilized as secondary raw materials. This model focuses on the recycling of materials and energy (Tátraaljai and Pukánszky 2020).