Each plastic film container has a small ID card and a triangular symbol, which is usually at the bottom of the plastic film container. There are 1 ~ 7 numbers in the triangle, and each number represents a plastic film container. Their production materials are different, and there are different taboos in application.

   "No. 1" stands for polyethylene terephthalate (PET, commonly known as polyester resin), which is commonly used to make mineral water bottles and carbonated beverage bottles. When the beverage bottle is used, it is heat-resistant to 70 ℃, which is only suitable for warm or frozen drinks. When it is filled with high-temperature liquid or heated, it is easy to deform, and substances harmful to human body will melt out.

   "No. 2" stands for high density polyethylene plastic film (HDPE), which is mostly used to make containers for cleaning products and bathing goods. Cleaning is not complete, and it is advocated not to recycle.

   "No. 3" stands for polyvinyl chloride (PVC), which is rarely used in food packaging. It is best not to purchase.

   "No. 4" stands for low density polyethylene plastic film (LDPE), which is commonly used for the production of fresh-keeping film, plastic film and so on. The heat resistance of the fresh-keeping film is not strong. Generally, the qualified polyethylene fresh-keeping film will show hot melting when the temperature exceeds 110 ℃, leaving some plastic film preparations that cannot be decomposed by the human body. Therefore, the use of fresh-keeping film to wrap the food surface for heating should be prevented.

   "No. 5" stands for polypropylene (PP), which is used to produce microwave oven lunch boxes. The only plastic film box that can be put into the microwave oven can be reused after careful cleaning.

   "No. 6" stands for polystyrene (PS), which is commonly used in the production of bowl instant noodle boxes and fast food boxes. It is heat-resistant and cold resistant, but it can not be put into the microwave oven, and can not be used to carry strong acids (such as orange juice) and strong alkaline substances. It will decompose polystyrene harmful to human body, which is easy to cause cancer.

   "No. 7" stands for polycarbonate (PC) and other categories. PC is a kind of data widely used, especially for making milk bottles, space cups, etc. If the plastic film container you purchased is numbered 7, you can reduce the occurrence of damage by the following methods: ① do not heat when using; ② Do not use dishwasher and dryer to clean containers; ③ Keep the container from direct sunlight; ④ Before the first use, clean it with baking soda powder and warm water and dry it naturally at room temperature, because bisphenol A will release more during the first use and long-term use; ⑤ If the container has any falling injury or damage, it is recommended to stop using. If there are fine pits on the surface of the finished plastic film, it is easy to hide bacteria; ⑥ Prevent the reuse of aged plastic film appliances. If you are still worried that plastic film products will cause damage to human body at high temperature, it is suggested that it is best not to use it to hold high-temperature liquid, but to use containers of ceramics, steel cups, glasses and other materials. This can not only reduce the damage to human body, but also make the environment better by reducing the use of petrochemical products.

   The debate on whether bisphenol A is harmful to health, especially children's health, has been going on for a long time in the industry. Recently, the conclusion of this debate is becoming brighter and brighter. There are numerous regulations and restrictions restricting BPA in North America. All the production companies exclaim that BPA is urgent now!