Each plastic product has a triangle with an arrow at the bottom, which is a "recycled" sign. There are Arabic numerals from 1-7, and the difference in Arabic numerals represents the different properties and different uses of this plastic material. It's like the identification of plastic products.　　
The number "1" means that the material of the plastic is PET, that is, polyethylene terephthalate, common mineral water bottles, carbonated beverage bottles, etc., heat-resistant to 70°C, easy to deform, and dissolve harmful substances to the human body; use After 10 months, the carcinogen DEHP may be released; it cannot be placed in the car in the sun, and it cannot be filled with alcohol, oil and other substances. The bottle with this logo can no longer be filled with water after use, please throw it in a recyclable trash can and let it be recycled.　　
The number "2" means that the plastic material is HDPE, which is commonly used as packaging bottles for cleaning products and shower products. Not used for food packaging.　　
The number "3" means that the material of the plastic is PVC. This kind of material is easy to produce harmful substances when it is high temperature, and it will even be released during the manufacturing process. After the toxic substances enter the human body with food, it may cause diseases such as breast cancer and birth defects of newborns. At present, containers of this material are rarely used for packaging food. If it is in use, do not let it heat up.　　
The number "4" means that the material of the plastic is LDPE. General products are cling film, plastic film, etc. The heat resistance is not strong. Generally, qualified PE cling film will melt when the temperature exceeds 110°C, leaving some plastic preparations that cannot be decomposed by the human body. In addition, when food is wrapped with plastic wrap and heated, the fat in the food can easily dissolve harmful substances in the plastic wrap. Therefore, when the food is put into the microwave oven, the wrapped plastic wrap must be removed first.　　
The number "5" means that the material of the plastic is PP. High temperature resistant, more common in microwave lunch boxes. Can be reused after careful cleaning. Need special attention, some microwave lunch boxes, the box is indeed made of No. 5 PP, but the lid is made of No. 1 PE. Because PE cannot withstand high temperatures, it cannot be placed in the microwave together with the box. To be safe, remove the lid of the container before putting it in the microwave.　　
The number "6" means that the material of the plastic is PS. It is more common in bowls of instant noodle boxes and fast food boxes. It is heat-resistant and cold-resistant, but cannot be placed in a microwave oven to avoid the release of chemicals due to excessive temperature. And can not be used to contain strong acids (such as orange juice), strong alkaline substances, because it will decompose polystyrene, which is not good for the human body, and is easy to cause cancer. Therefore, you should try to avoid using fast food boxes to pack hot food.　　
The number "7" represents the plastic material other than PVC and polystyrene or a composite material of multiple plastic materials. It is more common in kettles, drinking cups, and baby bottles. High temperature resistance, can be used repeatedly, but can not be heated in a microwave oven.