ASO Co., Ltd.

 Most of our plastic bags for pharmaceuticals are additive-free types. Basically, additive-free raw materials can only be found in radical-polymerized LDPE. This is because LLDPE always uses a catalyst in the reaction for ionic polymerization.

 Ordinary LLDPE uses a chlorine-based catalyst containing titanium tetrachloride. Chlorine is therefore corrosive, so calcium stearate is added to neutralize it. Calcium chloride, stearic acid, and other byproducts are then produced. There are some non-chlorine catalyst types, but most are of this type.

 Next, LDPE is produced by radical polymerization (active polymerization), so in principle no catalyst is used. Therefore, immediately after polymerization, polyethylene is additive-free (except for radical initiators, contamination, etc.), but the aforementioned additives are added as required in subsequent processes.

 Some say it would be better to use no additives, but considering productivity (cost) and handling, it may be unavoidable to add additives. Therefore, it is important to choose whether or not to use additives according to the application and purpose.