Cold seal adhesives are a popular choice for many flexible packaging applications, offering advantages such as increased line speeds and decreased waste. However, they can be subject to certain cold seal adhesive problems that impact efficiencies as well as product performance and functionality if not resolved.
Gain insight into some of these common problems, their causes and how to address them.
Also known as high cling or poor resistance, blocking is when the reel is difficult to separate or the cold seal may be transferring to the opposing surface during unwinding.
The following issues cause blocking:
- Wrong release lacquer/film
- Too high or too low of a release lacquer coat weight
- Under-dried cold seal adhesive
- Too high of a cold seal adhesive coat weight
- Excessive winding tension
- Under-stirring of the cold seal adhesive
Another common cold seal adhesive problem is anchorage, or adhesion. Poor adhesion is often caused by under-drying or under-stirring of the cold seal adhesive. It can also be triggered by the wrong cold seal and substrate combination.
Scumming, also referred to as ghosting or streaking, occurs when the adhesive continues to trail at the end of the cold seal. This results in excess adhesive usage and can cause production line issues.
Common causes of scumming include:
- Under-drying or under-stirring
- Incorrect cold seal adhesive grade for the application
- Poor adhesion to the base film
Addressing Common Cold Seal Adhesive Problems
While blocking, anchorage and scumming are common problems, they can be easily avoided if working with the right adhesive supplier. Bostik partners with customers, evaluating the entire process and its materials ahead of time.
An important preventive measure, this evaluation helps us better understand the process and what type of cold seal adhesive is right for the application.
Contact a Bostik expert if you’re having any of these cold seal adhesive problems, and we’ll be happy to address them.