The grade of 1 to 7 for plastics represents different properties and uses

No. 1 plastic: PETE, commonly used for mineral water bottles, carbonated beverage bottles, etc. Dress up for warm or cold drinks only. If full of high temperature liquid, or heating is easy to deformation, and release harmful substances to the human body.
No. 2 plastic: HDPE, common use for cleaning products, bath products, etc. If you want to reuse, need to be thoroughly cleaned before use.
No. 3 plastic: PVC, commonly used for raincoat, building materials, etc. Good plasticity, can't pack food. This material is prone to produce harmful substances when exposed to high temperature, and even releases toxic substances during the manufacturing process.
No.4 plastic: LDPE, common use for plastic wrap, etc. People often put food covered with plastic wrap in the microwave, which can cause the wrap to release toxic substances.
No. 5 plastic: PP, common use for microwave special meal box. This is the only plastic case that can be put in the microwave and reused after a thorough cleaning.
No.6 plastic: PS, common use for bowl instant noodle boxes and fast food boxes. High temperatures release chemicals that are harmful to human health.
No. 7 plastic: PC is commonly used for kettles, water cups, milk bottles, is a kind of material that is widely used.