UV curable pressure sensitive hotmelt adhesives are successfully have been used for label, tape and self adhesive insulation materials for several years. Although there is only a limited range of crosslinkable raw materials available, formulation of these materials has opened a wide range of new adhesives. Adhesive formulation is needed to tailor a product to specific application or customer requirements. Besides conventional formulation with non-reactive tackyfier resins, Collano discovered additional routes. Compounding with UV reactive additives results in chanced viscosity and adhesion properties. In the presence of a UV curable base resin, these additives do not require a further photoinitiator system and establish a covalent bond to the base polymer. The chemical bond between additive and base polymer, results in very low out-gassing or fogging values. Furthermore the additives reduce the melt viscosity significantly and make the products suitable for direct coating of temperature sensitive materials like polyethylene. The reduced melt viscosity further opens the possibility to utilize specialty additives like thermal expandable fillers. The novel formulation technique adds another dimension to satisfy the market needs with UV curable pressure sensitive adhesives and therefore further develop an environmentally safe adhesive technology.
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