Meaning
The theoretical bond strength of a pure polymer is often compromised when additives migrate to the surface and interfere with the fusing process. Seal Strength suppression occurs when lubricants, antistatic agents or moisture prevent the polymer chains from two separate layers from tangling together during a heat seal. This results in a package that can be opened with very little force.
Additive Interaction
Chemicals meant to improve handling can have negative effects on the final assembly. High concentrations of slip agents lead to seal strength suppression because they create a barrier that heat cannot easily remove. A converter must balance the need for low friction with the need for a secure closure.
Bond Failure
Integrity of the package is lost when the seal peels apart under the weight of the product. Monitoring for seal strength suppression involves regular pull tests on the production line to ensure that the bond meets the minimum requirements. Unexpected failure usually points to a change in the resin formulation.
Surface Contamination
Dust or oils from the environment can also lead to this phenomenon. Keeping the sealing area clean reduces the risk of seal strength suppression and ensures that the thermal energy is used only to melt the polymer.
