How are membranes classified?
LDPE film. LDPE film is mainly made by extrusion blow molding and T molding. The LDPE film is a flexible and transparent film, non-toxic and odorless, and the thickness is between 0.02 and 0.1 L. It has good water resistance, moisture resistance, drought resistance and chemical stability. A large quantity of general moistureproof packaging and frozen food packing used in food, medicine, daily necessities and metal products. But for moisture absorption, moisture resistance requirements of higher goods, you need to use better moisture film and composite film packaging. LDPE film has high permeability, no fragrance and low oil resistance. It can not be used for the packing of oxidizable food, flavor food and oily food. But it is breathable so that it can be used for fresh packing of fruits, vegetables and other fresh goods. LDPE film has good thermal adhesion and low temperature sealing property, so it is often used as bonding layer and thermal seal layer of composite film, but because of its poor heat resistance, it can not be used as the thermal seal of the cooking bag.
Linear low density polyethylene film. LLDPE film is a new variety of polyethylene film developed recently, compared with the LDPE film, LLDPE film has higher tensile strength, impact strength, tear strength and puncture resistance is. With the same strength and service performance as LDPE films, the thickness of LLDPE films can be reduced to 20 to 25% of LDPE films, thus greatly reducing the cost. That is, the use of heavy packaging bags, the thickness is only 0.1, L can meet the requirements, can replace the more expensive polymer high density polyethylene. Therefore, LLDPE is suitable for daily necessities, frozen food packaging, but also a large number used as heavy packaging bags and garbage bags.
HDPE film. HDPE film is a kind of tough semi transparent film. Its appearance is milky and its surface glossiness is poor. The tensile strength, moisture resistance, heat resistance, oil resistance and chemical stability of HDPE films are better than those of LDPE films, and they can also be sealed by heat. But the transparency is less than that of LDPE. HDPE can be made into thin film with thickness of 0.01. L. Its appearance is similar to that of thin silk paper. It feels comfortable and is called "paper film". It has good strength, toughness and opening, and can be added with a small amount of light calcium carbonate to enhance the paper feel and reduce the cost. HDPE paper film is mainly used for making all kinds of shopping bags, garbage bags, fruit packing bags and all kinds of food packaging bags and so on. Because of its poor air tightness and no incense retention, the storage period of packaged food is not long. In addition, the HDPE film can be used as a heat sealing layer of the cooking bag because of its good heat resistance.
