Migration of slip agent
1. Separation of slip agent
The normal separation of the slip agent appears. A slip agent (herein referred to as an organic slip agent, excluding silicone powder) is uniformly dispersed in a layer of a "multilayer coextruded substrate". (Due to its incompatibility with the substrate resin) In a specific environment, a slip agent is deposited from the interior of the substrate to the surface of the substrate.
The abnormal separation of the slip agent appears. However, the separation of the slip agent is non-directional, and will separate out on the surface of the composite layer except that it will separate out on the surface of the heat-sealing layer of the PP/PE film.
Picture 1 - Migration of slip agent/additive ( picture is from google images)
2. Migration of slip agent
Based on the previous article, a composite PA/PE material is taken as an example. The coefficient of friction of the surface of the substrate is reduced, mainly due to the migration of the "slip agent".
Analysis: Under the condition (curing process) that the composite film is heated, due to the improved compatibility of the PA film and the PE film to the "slip agent", it has been separated out that "slip agent between the surface of the composite film and the interface between the PE film and the adhesive layer" will be absorbed into the "PE and PA film inside". It decreasing the absolute number of "slip agents between the surface of the composite film and the interface between the PE and the adhesive layer". Correspondingly, It is appears as an increase in the "coefficient of friction of the outer surface of the composite membrane" and an increase in the "interlayer peeling force". As the temperature of the composite film gradually decreases, the "slip agent in the film" will gradually migrate outward, the coefficient of friction of the outer surface of the composite film (the heat sealing surface of the heat sealing layer and the outer surface of the printing film) is gradually decreased.