Polypropylene microporous film manufacturing

日期:2019/6/17 9:00:54 / 阅读: / 来源:本站

Polypropylene microporous film manufacturing
There are four main methods for producing microporous films:
1) Using a high molecular weight, crystalline polypropylene, a conventional film blowing apparatus is used to form a hard elastic polypropylene film having a rubber-like, crystallized and elastic state, and then subjected to stretching from 10% to 300%. A large number of micropores can be formed, and a polypropylene microporous film can be obtained by heat setting.
2) Add a heterogeneous substance to the polymer, and then extract the pores with a solvent.
3) In the partially crystallized polypropylene base, a nucleating agent capable of producing β spherulites is added, and after the film is stretched, it is extracted with a non-polar solvent.
4) Irradiating the dielectric film with radiation, leaving a trace of damage at the penetration, using a locally modified material in the lesion to etch the etch rate much faster than the undamaged matrix material in some chemical agents, followed by Microporous or nuclear micropores
The polypropylene microporous film is basically manufactured by the first method. Compared with the second and third methods, it can be used in a conventional blown film apparatus because of low cost and avoiding environmental pollution caused by the use of a solvent. The produced polypropylene pore film is completely free of residual additives, and has excellent performance, and has low cost and high pore formation rate compared with the nuclear pore membrane.
The stretching process of the polypropylene microporous elastic film has a two-step method (this method is used in the early stage) and a one-step method.
The cheaper raw material for producing polypropylene rigid microporous elastic film is isotactic polypropylene with high crystallinity, the density requirement is 0.90 g/cm3, and the isotacticity requirement is about 95%. The pore size on the membrane is closely related to the relative molecular mass of the raw material. The larger the relative molecular mass, the smaller the pore size. The suitable relative molecular mass is more than 250,000, and the melt flow rate is usually 2-10 g/10 min.
Polypropylene microporous film manufacturing example
1) Raw materials: The isotacticity of polypropylene is greater than 98%.
2) Film formation: The T-shaped machine head is used for extrusion, the formed blank is cooled, and then stretched and shaped to obtain a polypropylene microporous film.
3) Product performance: The main properties of polypropylene microporous film developed by Shanghai Institute of Polymer Science, Fudan University and 2400 and 2500 polypropylene microporous film of Japan Polymer Plastics Co., Ltd. are shown in Table 2519, and their air permeability and pressure difference The size is proportional to the linear relationship. The transmission rate is 2500>Fudan PP>2400. If the pressure difference is 0.04MPa, 2400 is about
40 cm/(cm2.min), Fudan PP is about 55 cm3/(cm2.min), and 2500 is about 90 cm3/(cm2.min).

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