Pressure-sensitive adhesives (PSA) are organic materials based on self-adhesive polymers with adhesion and cohesion properties and used to bond surfaces . Three properties which are useful in characterizing the nature of PSA are tack (initial adhesion), peel adhesion (adhesion) and shear strength (cohesion). Scientific interest in UV-curable system developed in the 1940s, when the first patent was granted for unsaturated polyester styrene inks that polymerize readily under UV exposure . Ultraviolet (UV) cross-linking technology is well established in the market and allows the manufacturing of a wide range of various photoreactive UV-cross-linkable pressure-sensitive adhesives (PSA). Industrial applications of UV cross-linkable acrylic PSA have grown tremendously over the last 10 years. The balance between adhesive and cohesive strengths within the cross-linked layers is very important for the performance of UV-cross-linkable PSA. Dual cross-linking (UV and thermal) enables manufacturing of acrylic PSA layers with different adhesion-cohesion properties and offers opportunities to develop novel products in form of self-adhesive tapes with innovative features. UV radiation is used to induce cross-linking of the photoreactive acrylic PSA formulations containing suitable prepolymers, oligomers, unsaturated multifunctional monomers and conventional or unsaturated photoinitiators. Discussed herein is a new generation of photoreactive acrylic PSA that uses this dual (UV and thermal) cross-linking system. These dual cross-linkable acrylic PSA containing incorporated photoreactivity and thermal reactive cross--linking agents are characterized by excellent adhesive and cohesive performance and can be used for production of a wide range of self-adhesive materials.
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