1. The elasticity and flexibility of the film are better, and it is uniform and consistent.

2. The membrane material must have good biological stability and biocompatibility, and must undergo rigorous biological tests, including acute systemic toxicity tests and subcutaneous toxicity tests.

3. After the film material and the butyl rubber plug are combined, it is not easy to fall off, resulting in secondary pollution.

4. The membrane material should have good isolation properties and can effectively prevent the liquid from absorbing metal ions in the butyl rubber stopper.

5. It has good lubricity. Due to the movement of the butyl rubber stopper during the filling process with the liquid, good lubricity can ensure that the butyl rubber stopper moves efficiently on the conveying track and ensure the production efficiency of the pharmaceutical factory.

6. The membrane material must have good thermal stability and high temperature resistance to disinfection, because butyl rubber plugs have to go through various sterilization processes in different liquids, such as high-pressure wet-heat sterilization, dry-heat sterilization, and radiation-ray sterilization.