Changes in film properties over time
What film properties degrade over time and under what conditions should customer’s store film?
Answer
The changes that will occur with age are continued slip bloom and a masking of the Corona treatment, discoloration, loss of physical properties, and blocking or stretching of film. As a result, we typically recommend that customers use PE films in six months or less and honor age related film failures for that time period only.
If you purchase a film with a lot of slip, obviously slip bloom is the most immediate aging problem to occur. The slip will bloom to the surface and act as a lubricant and cover the treated surface, thus lowering the surface tension of the film. This reduces ink adhesion and lamination bond strength. The lower the slip content in the film, the less this effect will occur. In fact, a non-slip film will typically show very little treat loss for as long as one year.
The other aging problems that were mentioned above are all related to storage conditions. If the film is stored in excessively hot warehouses, the film will soften and stretch, resulting in bagginess and possibly blocking. Also, heat will accelerate the aging and degradation process of the film causing discoloration and loss of properties. The film may feel stiffer and become brittle.
Another storage problem is the presence of CO gas from combustion sources such as gas fork trucks, ovens, and dryers. The CO gas may react with compounds in the film and cause it to turn yellow or pink.