Let's talk about the advantages of PET first:

It has good mechanical properties, the impact strength is three times that of other films, high bending resistance, oil resistance, grease resistance, acid resistance, and resistance to most dissolved gases and water vapors.

Moreover, it has low permeability, that is, it has excellent gas blocking, water, oil and odor properties. It can block general ultraviolet rays. It is non-toxic, tasteless, hygienic and safe.

Let's talk about PE again:

It has good chemical stability and can resist most acids, alkalis, organic solutions and hot water. Electrical insulator, good chemical stability, tensile resistance, non-toxic and harmless.

The combination of the two is definitely a pivotal role.