Polyethylene is odorless, non-toxic, feels like wax, has excellent low temperature resistance (minimum use temperature can reach -70 ～ -100 ℃), good chemical stability, can withstand most acid and alkali erosion (not resistant to oxidizing properties) Acid), insoluble in ordinary solvents at room temperature, low water absorption, and excellent electrical insulation properties; but polyethylene is very sensitive to environmental stress (chemical and mechanical effects) and has poor heat aging resistance. The properties of polyethylene vary from species to species, mainly depending on the molecular structure and density. Products with different densities (0.91 to 0.96 g / cm3) can be obtained by using different production methods. Polyethylene can be processed by common thermoplastic molding methods (see Plastic Processing).
Divided by material: PE is divided into LDPE, LLDPE and HDPE.
According to the production process: PE flat pocket, ziplock bag, chain bag, envelope bag, punching tote bag, hand bag, zipper bag, PE film.
1. The PE flat bag is the simplest production process. After the film is blown by the machine, it is cut into bags one by one on the bag making machine and sealed at the bottom. 2. Ziplock bag is provided with a bone when the film is blown by the machine, which can be sealed manually. Unlike zipper bags, these two bags are generally confusing.
3. The zipper bag is a bag made of PE film with two zipper chains (this zipper chain is separately produced). The bag has generally wide indentations on both sides, while the zipper bag is not. Ziplock bags print less colors, while chain bags can print complex patterns.
4. The envelope bag has a tongue like an envelope. A strip of glue is attached to the tongue, and the bag can be sealed by folding it over. More general clothing. There is also a courier bag as an envelope bag.
5, punching tote is to make a hole in the top of the flat pocket to facilitate lifting the bag.
6. The hand-held tote is to add a plastic film strip on the top of the bag to facilitate the lifting of the bag. This process is labor-intensive and the cost is relatively high.
7, zipper bag is to put a zipper strip on the bag seal and bring a zipper cap.
8. PE film is a film that is not made into a bag after the machine is blown out. It is also divided into winding film and shrink film. Commonly used in the market are calculated by individual and by length (volume). (Bags) are mainly used for small accessories packaging. Most accessories bags for PE bone pockets made of electronics have anti-static effects. The mouth of the bag is flat and self-sealing. (Roll) bags need to be cut by themselves (for material packaging) and printed cuts (for supermarkets).
In addition, the cling film made of PE material can also be called a PE bag. Note that the cling film that is in direct contact with food must be made of PE material (the other is generally PVC), which is safer for the human body. Identification method: PVC cling film has better transparency, stretchability and stickiness than PE cling film. When the PVC cling film is burned with fire, the flame will be black, emit black smoke, have a pungent odor, will not drip oil, and will automatically extinguish after leaving the source of fire. When the PE cling film burns, the flame is yellow, odorless, drips oil, and can continue to burn after leaving the fire source.
