ASO Co., Ltd.

Polyethylene is typically melted at around 150°C during the inflation process, which is generally considered sufficient to eliminate microorganisms.

 We have previously explained it in this way.

However, for polybags intended for pharmaceutical packaging, stricter measures are required.

During the inflation process, polyethylene tubing is formed using air and wound into rolls.
If microorganisms or fine particles are present in the air, there is a potential for microbes to adhere to the inner surface of the polyethylene tubing.

Nevertheless, microorganisms are unlikely to survive for long periods under nutrient-free conditions.

In addition, rolled raw materials are exposed to risks of microbial contamination from falling bacteria, human contact, or machinery during roll handling and bag-making processes.

 Storage conditions and working environments inside the bag-making area are also factors that contribute to microbial adherence.

Even in cleanrooms, ISO Class 3 or higher environments contain particles larger than 1 μm, making complete microbial elimination difficult.

Therefore, sterilization is essential.

Due to the heat sensitivity of polyethylene, the following sterilization methods are commonly used:

Currently, the mainstream methods are gamma irradiation and electron beam irradiation.

Sterilization is meaningless if the product becomes contaminated afterward.
Proper packaging and transportation procedures are essential to maintain sterility.

Even with appropriate sterilization, attention must be paid to production environment control and endotoxin management.

High microbial loads increase the risk of foreign matter contamination, even if Gram-negative bacteria are absent.

Additionally, gamma or electron beam irradiation can generate radicals in the polyethylene film, potentially causing chemical changes, such as:

Radical suppression remains a technical challenge, and our company has been addressing this issue for many years.

Ultimately, humans are the ones performing the work.
Even in cleanrooms, the largest source of contamination is personnel, but humans are also the most adaptable “precision inspection device.”

For this reason, continuous education and training of operators is the most critical theme for maintaining cleanroom standards and ensuring product sterility.