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What is the production process of LLDPE blown ultra-thin film?

by:LINYANG     2020-02-20


Linear low density polyethylene (LLDPE)What is the production process of blow-molded ultra-thin film?

because the relative molecular mass distribution of LLDPE is narrow and the molecular structure is a linear structure with a short branched chain on the main chain, compared with LDPE, its melt viscosity is large, viscosity is not sensitive to the change of shear rate, so the processing temperature is about 10 ~ higher than LDPE ~ 25 ℃, I . e. 200- Between 230 ℃, and usually from the feeding end to the die gradually rising temperature distribution line or straight temperature distribution line. The specific temperature is: the rear section of the extruder- 180 ℃, middle 180- 195 ℃, front section 200- 210 ℃, joint ~ 2100C, nose and die-230 ℃.

The Tensile viscosity of LLDPE is lower than that of LDPE in a wide deformation rate range, I . e. it is softer during stretching, while LDPE is easier to stretch. 'Hardening' Therefore, when blowing LLDPE film, the airflow should be stable and the air volume should be large to ensure the stability of the film tube and the necessary cooling effect.

In addition, LLDPE has high extensibility. Under normal processing temperature and stretching rate, molecules are not easy to stretch orientation, therefore, the performance of the thin film is not sensitive to drawing ratio and blowing ratio, which is very beneficial to the adoption of larger die head and die gap. Usually the inflation ratio is taken (2-4): 1, and the drafting ratio is about 10:1.

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