Deep In Thought

Published: 23 Feb 2022

What are the symbols on plastic packaging?

The triangle symbol was first used to facilitate the sorting of bottles into individual material compartments on sorting lines specializing only in bottles. This initiative was developed because of the great waste crisis that the United States was going through at the turn of the 1980s and 1990s. The problem with the brand arose when it was chosen, as it strikingly resembled a brand that is a symbol of recycling. We will leave it up to you to assess the extent to which these two brands are similar.

Due to the escalating waste crisis, these brands have been adopted for all plastic packaging for unclear reasons. At present, it is already found on all packaging, including glass and metal. As you can see, these brands were never developed to inform or sort all plastic packaging. Therefore, this symbol does not indicate whether this material has been or will be recycled, but only indicates information about the base material from which it is made.

What is it for?

It could certainly be argued that the consumer can use this symbol before disposal as an aid to correct sorting, but in this case the plastics with numbers 3 and 7 (PVC and others) would be separated from the yellow bins, which, however, constitute a minimum volume in the total volume. plastics in yellow bins.

PVC, which can be found, for example, in water pipes or some packaging on PET bottles, should under no circumstances get into the yellow bins. PVC reprocessing requires special conditions to prevent the formation of toxic chlorine compounds. PVC should therefore end up in specialized recycling points, in the worst case in a landfill. Plastics marked 7 (other) are diverse in type, so their recycling in small quantities does not make financial sense and is not technically possible.

The recycling symbol is almost never used even on sorting lines, where the contents of all yellow garbage cans travel. The vast majority of all sorting lines in the Czech Republic are manual, and it is not in the power of their employees to look for this symbol on every piece of plastic and sort it correctly according to it. Therefore, it often happens on sorting lines that only easily recognizable waste with the same material composition is sorted. These wastes include drinking bottles made of PET, foil made of LDPE or drugstore bottles made of HDPE. The rest of waste from polypropylene (PP), polystyrene (PS) or less recognizable waste is often unsorted and ends up in incinerators or landfills.

Advanced sorting lines, which have optical sorting in the separation process, are able to sort far more material than manual lines because they are almost fully automated and use detectors and cameras to detect the material composition of each individual piece of plastic. Unfortunately, this line is only one in about 120 in the Czech Republic.

Not 1-PET is like 1-PET

There are around 2,000 types of plastics in the world (some figures indicate up to 6,000 types) if we look at the brand. Here it is important to note that even a single plastic, which has, for example, the 1-PET brand, can have several different subspecies, such as R-PET, G-PET, C-PET and A-PET, and each of them has more or less less different properties, and especially different melting points that must be achieved in a conventional type of recycling. For these reasons, nowadays only PET bottles are recycled in the Czech Republic, other PET material ends up in landfills, in the best case in incinerators.

Why do plastics actually sort?

Different types of plastics have to be sorted mainly due to melting point and miscibility. As already mentioned, each plastic has a different melting point. When reprocessing plastics, we usually work with the lowest possible temperatures to reduce costs and prevent the breakdown of individual chemical chains. Therefore, if two plastics with different melting points were processed, either at low temperatures one of the plastics would not melt, or at high temperatures the other type of plastic would begin to degrade rapidly .

Another reason for the need to separate plastics before recycling, at least into individual material groups, is their mutual immiscibility. This can best be illustrated by the example of water and oil – even if the two substances are in a liquid state, they do not mix with each other and form two precisely separated layers, each containing a certain percentage of the other substance. The same happens with most mixed plastics, which would liquefy and subsequently cool two or more different layers. Using individual technologies, these individual layers would clearly degrade the resulting recycled material. However, there are also plastics that can be mixed relatively well, such as HDPE and LDPE or in small amounts of HDPE with LDPE, as they come from a similar group of polymers (polyolefins) and have sufficiently similar polymer chains.

So is this brand useful?

These indicative “recycling” symbols clearly have their place in the industry, where they help to at least roughly identify the materials. In domestic recycling, they also have some reason to prevent PVC and type 7 plastics from entering yellow bins. But how many people actually use these symbols in recycling, however, can also answer for themselves.

The purpose of this article was certainly not to remove them from the packaging, but it is worth mentioning that these symbols are often misused or misunderstood as a sign of some previous or future recycling of this product after being placed in the correct bin. And that, as we have explained in this text, is not true, and plastics will not last long. We clearly see the future in the sorting of plastics in the use of optical sorting, which are able to recognize the type of plastic in milliseconds.