Cling film is a kind of plastic packaging product, usually made by polymerization reaction with ethylene as the masterbatch. Cling film can be divided into three categories: the first is polyethylene, referred to as PE; the second is polyvinyl chloride, referred to as PVC ; The third is polyvinylidene chloride, or PVDC for short. From a physical point of view, the cling film has moderate oxygen permeability and moisture permeability, regulates the oxygen and moisture content around the fresh-keeping product, blocks dust, and prolongs the fresh-keeping period of the food. Therefore, it is necessary to choose different plastic wraps for different foods.
The cling film on the market is roughly divided into two types, one is ordinary cling film, which is suitable for refrigerator preservation; the other is microwave cling film, which can be used for refrigerator preservation and microwave oven. The latter kind of cling film is far superior to ordinary cling film in terms of heat resistance and non-toxicity. Therefore, consumers should pay special attention to the choice of use, and use it separately.
Most of the cling film and commonly used plastic bags on the market are made of ethylene masterbatch as raw material. According to the different types of ethylene masterbatch, cling film can be divided into three categories.
The first type of polyethylene, PE for short, is mainly used for food packaging. The film we usually buy for fruits and vegetables, including the semi-finished products purchased in supermarkets, are all used for this material;
The second type is polyvinyl chloride, or PVC for short. This material can also be used for food packaging, but it has a certain impact on the safety of the human body;
The third type is polyvinylidene chloride, or PVDC for short, which is mainly used for the packaging of cooked food, ham and other products.
When buying cling film, it is first recommended to buy a self-adhesive cling film made of polyethylene (PE), especially when preserving meat, fruits, etc., because in terms of safety, PE cling film is the safest . If you want a longer shelf life, it is recommended to choose polyvinylidene chloride (PVDC), because the plastic wrap of this material has better moisture retention, and the shelf life of the three materials is the longest.
Polyvinyl chloride (PVC) cling film has good transparency, good viscosity, good elasticity, and relatively cheap price, so it has become the choice of many people, but it must be noted that it cannot be used for preservation of oily food, because it is made of poly The resin composed of vinyl chloride resin, plasticizer and antioxidant is non-toxic. However, the main auxiliary materials such as plasticizers and antioxidants are toxic. Polyvinyl chloride plastic products will slowly decompose hydrogen chloride gas at a higher temperature, such as 50 ℃, which is harmful to the human body. Vinyl chloride products should not be used as food packaging and cannot be used at high temperatures.