Talking about the meaning of the numbers on the disposable packaging box

Take a closer look at the lid or bottom of the disposable packaging box, you will find some number signs. What exactly does this number mean?
 
The numbers we see on the packaging box are actually used for plastic recycling and sorting. The different numbers represent the resin's identity code. The numbers 1 to 6 respectively represent 6 specific plastics and are written in a triangle (usually composed of three connected arrows), which is used as a mark on the bottom of the bottle. The number 7 represents other plastics or mixed plastics. These numbers are not intended to provide people with safety guidance or their intended use, nor can they be judged by their applicability. However, usually these figures have certain directivity, the following is our summary of the meaning of these figures.
 
No. 1 polyethylene terephthalate (PET): plastic bottles of mineral water, fruit juice, carbonated drinks are made with it;
 
No. 2 high-density polyethylene (HDPE): a common water-filled bucket, which is used;
 
No. 3 Polyvinyl Chloride (PVC): plastic used in general plastic pipes;
 
No. 4 polyethylene (PE): common cling film, plastic film, etc., not suitable for high temperature use;
 
Polypropylene (PP) No. 5: This is the most heat-resistant material, which is commonly used in plastic appliances heated by microwave ovens;
 
No. 6 polystyrene (PS): Now it is used for many milk tea cup lids;
 
No. 7 often refers to several plastics such as polycarbonate (PC): most baby bottles use PC as a raw material.