PLA packaging bag is the abbreviation of all biodegradable bags. It uses low-density polylactic acid as raw material, flat extrusion and up-blowing method to make a microfilm with a thickness of 0.01~0.014mm and a width of 600~1000mm. PLA packaging bags can be decomposed into carbon dioxide and water under certain conditions. Packaging bags include ordinary packaging bags, colored packaging bags, and photodegradable packaging bags.
Ordinary packaging bag is a colorless transparent packaging bag film produced with a single component of low-density polyethylene resin; colored packaging bag is based on the photosynthesis of different plants, and the required spectrum uses the principle of artificial complementary color, and coloring is added to the polyethylene resin The production of red, white, black and other colored packaging bag films, and colored packaging bag films increase the production more than ordinary packaging bag films, and have many unique functions.
PLA packaging bag is a kind of polylactic acid packaging bag similar to paper, which is different from medium and high molecular weight high-density polyethylene which is extruded and blow-molded to produce micro-film. The appearance and feel of PLA packaging bags are similar to those of tissue paper, with good opening, strength, toughness, moisture resistance, fragrance retention, and oil resistance. Packaging bags of this material are mainly used for shopping bags, garbage bags, fruit packaging bags and various food packaging bags.
The production process of PLA packaging bags is basically the same as that of ordinary packaging bags, that is, the flat extrusion and upward blowing method is adopted. The extrusion temperature is controlled as follows: 160°C~170°C in the rear section, 200~220°C in the middle section, 200°C~220°C in the front section, and 200°C of the die head temperature. The inflation of PLA packaging bags is relatively large, generally 4~5. According to some data, an inflation ratio of 8.5 is the best process condition for obtaining equal vertical and horizontal performance. However, in actual production, the film tube will not be inflated if the inflation is too large. Stability, drift and uneven film thickness.
The condensation line of PLA packaging film is higher, and the neck of the film tube is 3~4 times longer than that of the ordinary film. This is to stretch at a lower temperature (the temperature of the highest crystallization rate) to increase the strength of the film. Usually, when the ratio of neck length to die diameter of the machine head 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-necked membrane tube, the wind direction of the wind ring is required to be parallel to the membrane tube, and the wind blows upwards, playing a role of supporting the membrane tube.