PLA packaging bag is the abbreviation of all biodegradable bags. It uses low-density polylactic acid as raw material to form a thin film with thickness of 0.01 ~ 0.014mm and width of 600 ~ 1000mm by flat extrusion and blowing. PLA packaging bags can be decomposed into carbon dioxide and water under certain conditions. Packaging bags include ordinary packaging bags, colored packaging bags, photodegradation packaging bags, etc. Ordinary packaging bag is a colorless transparent packaging bag film produced by using a single component of low-density polyethylene resin; Colored packaging bags are red, white, black and other color packaging bag films produced by adding colorants to polyethylene resin according to the photosynthesis and required spectra of different plants. Colored packaging bag films increase production more than ordinary packaging bag films and have many unique functions.
PLA packaging bag is a kind of paper like polylactic acid packaging bag. It is different from medium high molecular weight high-density polyethylene, which is extruded and blow molded to produce micro film. The appearance and hand feel of PLA packaging bag are very similar to that of thin silk paper, with good opening, strength, toughness, moisture resistance, fragrance retention and oil resistance. The packing bag of this material is mainly used as shopping bag, garbage bag, fruit packing bag and various food packing bags.
The production process flow of PLA packaging bag is basically the same as that of ordinary packaging bag, that is, flat extrusion and up blowing method is adopted. The extrusion temperature is controlled as follows: 160 ℃ ~ 170 ℃ in the rear section, 200 ~ 220 ℃ in the middle section, 200 ℃ ~ 220 ℃ in the front section and 200 ℃ in the head. The inflation of PLA packaging bag is relatively large, generally 4 ~ 5. It is introduced that when the inflation ratio is 8.5, it is the best process condition for making equal vertical and horizontal performance. However, in actual production, if the inflation is too large, the film tube will be unstable, drift and uneven film thickness.
The condensation line of PLA packaging bag film is higher, and the film pipe neck is 3 ~ 4 times longer than that of ordinary film, This is to stretch the membrane at a lower temperature (maximum crystallization rate temperature) and improve the strength of the membrane. Generally, when the ratio of neck length to die diameter is 3 ~ 5, the operation is convenient, the membrane tube is stable and the quality is good. In order to ensure the stability of the long neck membrane tube, the wind direction of the air ring is required to be parallel to the membrane tube and blow upward, which plays a role of supporting the membrane tube.
