What Is LDPE?

Published:

2023-08-23


Low-density polyethylene, also known as high-pressure polyethylene (LDPE), is the lightest variety of polyethylene resins. It is milky white, odorless, odorless, non-toxic, and waxy particles with a matt surface. It has good flexibility, extensibility, electrical insulation, transparency, easy processing and certain air permeability. It has good chemical stability, alkali resistance and general organic solvent resistance.

The main characteristics of low-density polyethylene are as follows: (1) The film is slightly opalescent transparent and soft. The strength is smaller than that of high-density polyethylene, and the impact strength is greater than that of high-density polyethylene. (2) Cold resistance, low temperature resistance and higher temperature resistance. The thicker film can withstand the sterilization process of 90°C hot water immersion. (3) Good moisture resistance, stable chemical properties, and insoluble in common solvents. (4) It has greater air permeability, so when it is used as a food packaging that is easy to oxidize, the storage period of its contents should not be too long. (5) The grease resistance is poor, and the product can be slowly swelled. When packing oily foods, the food will have a hala taste after long storage. (6) Long-term exposure to ultraviolet rays and heat will cause aging, which will affect its physical and dielectric properties. (7) The melting point is 110~115℃, and the processing temperature is 150~210℃. If it is in an inert gas, the temperature can reach 300℃ and still be stable. But the melt and oxygen are prone to degradation.

Application range of low-density polyethylene: suitable for food packaging such as seasonings, cakes, sugar, candied fruit, biscuits, milk powder, tea, fish floss, etc. Packaging of medicines such as tablets and powders, and packaging of fiber products such as shirts, clothing, knitted cotton products and chemical fiber products. Daily chemical products packaging such as washing powder, detergent and cosmetics. Due to the poor mechanical properties of single-layer PE film, it is usually used as the inner layer of composite packaging bags, that is, the heat-sealable substrate of multilayer composite film.