1. Peel strength changes over time
Regardless of the surface gloss, the surface of the object is covered with tiny holes that are difficult to see with the naked eye. Although the pressure-sensitive adhesive is cross-linked, it still has some deformation and fluidity, especially the polymer portion that is not involved in crosslinking.
Over time, the pressure sensitive adhesive gradually penetrates into the voids, forming an "anchor." In addition, when the pe protective film is attached, although the pressure is large, the contact area between the pressure sensitive adhesive and the surface of the material is not large, and the contact area gradually increases with time, and between the pe protective film and the protected surface. The force is also gradually increasing. Both effects increase the peel strength over time.
2. Mechanism aging
The main chain of the acrylate pressure sensitive adhesive is a saturated chain. Generally, the thermal energy is difficult to break the main chain, and the aging mechanism is mainly ultraviolet aging; the aging of the substrate is mainly ultraviolet aging. For example, the tensile strength of PE film substrate after aging for 1 week in 80 ° C environment and uv lamp supplier 30W ultraviolet light, the results show that the normal use temperature has little effect on the aging performance, and the effect of ultraviolet light It is bigger. However, under the dual action of heat and ultraviolet light, there is synergistic aging.
3. Similar compatibility mechanism
Acrylate pressure sensitive adhesive is a relatively polar material and is easily compatible with polar materials such as acrylates, polyesters, and polyurethanes, making it difficult to remove the pe protective film. Sometimes small molecules that are not involved in cross-linking of pressure-sensitive adhesives will enrich the surface. If the surface between the protected surface material and these small molecules is large, small molecule migration will occur.