Six main raw materials for stretch film
The stretch film is generally made using two processes: blow molding and tape casting. The thickness of the cast polyethylene stretch film is uniform, but due to its high price, it is currently rarely used. Blow molded polyethylene stretch film is made from blow molded grade PE particles blown by a blow molding machine, which has a lower cost and is therefore the most widely used.
1. Polyvinylidene chloride: As a single-layer film, it can also be used in soft cans. It can be used as a packaging material for ham and sausages, and has excellent sealing, ligation, heat shrinkage, and gas barrier properties. Polyvinylidene chloride can also be used as a coating for film materials such as nylon and polyester. In addition, there are also excellent high barrier polyvinylidene chloride films used as composite substrates for cooking bags and for high-temperature and high-pressure sterilization.
2. Polyester: It has excellent transparency, heat resistance, and wear resistance. There are two types of film thickness: 12 microns and 25 microns, and printing is carried out on polyester, which can be used as a cover material for cooking bags or dish containers.
3. Nylon: As a base material for packaging soft cans, it is indispensable. There are two types: biaxial stretching and unstretched. Biaxially stretched nylon film not only has excellent heat and cold resistance, but also has good tear strength and pinhole resistance. Therefore, it can be used in combination with other raw materials.
4. Polypropylene: It has good transparency, oil resistance, and better heat resistance than special polyethylene, so it can be used as a sealing layer for cooking bags and containers.
5. Aluminum foil: Aluminum foil is made from electrolytic aluminum with a purity of over 99% and is rolled. When used as a packaging material, aluminum foil is the only metal substrate in the packaging material. The thickness of aluminum foil used in the steaming bag is 7-15 microns, while the thickness of aluminum foil used in the steaming container is 50-130 microns.
6. High density polyethylene: The special high-density polyethylene used for soft cans has already been sold in Japan. Although this film has poor gas barrier properties, it can be used as a sealing layer due to its excellent tensile strength, elongation, tear strength, and good sealing adaptability. Its maximum heat resistance temperature is 120 ℃.
