There are some inherent disadvantages in the blown film extrusion process
Poor film thickness uniformity:
During the film blowing process, the flow characteristics of the melt during extrusion and blowing may cause uneven film thickness distribution.
Improper die gap adjustment, uneven cooling air volume, and uneven heating temperature around the die head may affect the uniformity of film thickness.
Low cooling rate:
The film needs to be cooled and solidified after extrusion, but the cooling rate is restricted by many factors, such as cooling air volume and the design of the cooling air ring.
Poor cooling effect may lead to problems such as reduced film transparency and stickiness, and even affect normal production.
Low film transparency:
The transparency of the film produced by the blown film process may be affected by many factors such as raw materials, extrusion temperature, and cooling effect.
The crystallinity of the resin raw material, poor melt plasticization, and poor cooling effect may all lead to reduced film transparency.
Low output:
Due to the limitations of cooling conditions, the winding line speed generally does not exceed a certain range (such as 10m/min), which limits the output of the film.
In addition, in order to improve the quality of the film, such as ensuring thickness uniformity and transparency, a certain amount of output may need to be sacrificed.
Other process difficulties:
For certain specific materials (such as PLA), blown film extrusion also faces challenges such as low melt strength, poor toughness, and low crystallinity.
These characteristics may lead to problems such as difficulty in film formation, easy breakage of the film, or poor heat resistance.
