Novel Metal Containing Crosslinkers for High Solids and Hot Melt AcrylicPressure Sensitive Adhesives – The Benefits of Reversible Crosslinking

摘要

This paper will introduce a new line of crosslinkable raw materials for the manufacture of highsolids, solvent-recoverable acrylic pressure sensitive and hot melt adhesives. These materialsare classified as soluble divalent metal salts of alpha-beta ethylenically unsaturated carboxylicacids. When used as a co-reactant in the preparation of a PSA or hot melt PSA acryliccopolymer adhesive resin prepared by either bulk, solution or emulsion polymerization, theyintroduce ionic crosslinks into the backbone. The ionic crosslinks yield thermoset behaviour andenhanced adhesive properties at ambient temperatures . Adhesive polymers containing thesematerials exhibit higher glass transition temperature (Tg’s) and increased modulus or stiffnesscompared to conventional acrylic adhesive polymers, while maintaing sufficient tack to performas a pressure sensitive material. More importantly, adhesive resins prepared with these uniqueionic crosslinkers still exhibit thermoplastic behaviour or flow when heated to allow for ease ofapplication by breaking of the crosslinks. This “reversible crosslinking” phenomenon isdescribed and demonstrated by thermal analysis techniques and peel and shear adhesion tests.