The classification marks on the bottom of plastic bottles are used to indicate the type of plastic material. They are mainly used to distinguish different types of plastic materials. The marking system divides plastics into 7 categories, represented by numbers 1 to 7, corresponding to materials such as PET, HDPE, PVC, LDPE, PP, PS, and other categories. They are commonly found on beverage bottles, food packaging, and other daily containers.
PET (No. 1) is mostly used for mineral water bottles and carbonated beverage bottles. It has a heat resistance of 70℃ and may release harmful substances at high temperatures. HDPE (No. 2) is used for containers of cleaning products and can be reused but must be thoroughly cleaned. PVC (No. 3) is rarely used for food packaging as it may produce toxic substances when heated. LDPE (No. 4) is used for cling film and should not be used to wrap food when microwaving. PP (No. 5) is the only plastic material that can be microwaved, but the lid should be separated. PS (No. 6) is used for instant noodle cups and other items and is not resistant to high temperatures and strong acids or alkalis. PC (No. 7) is commonly found in water cups, baby bottles, etc. The usage restrictions corresponding to different marks are mainly related to heat resistance and chemical stability.
