Effect of Kaolin on Adhesion Property of Epoxidized Natural Rubber-based Pressure-sensitive Adhesive Using Gum Rosin as the Tackifier

The viscosity, loop tack, and peel strength of kaolin-filled epoxidized natural rubber (ENR 25 grade) adhesive was investigated using gum rosin as the tackifying resin. Kaolin loading was varied from 10—50 parts per hundred parts of rubber (phr), whereas the gum rosin concentration was fixed at 40 phr. Toluene was used as the solvent throughout the study. Polyethylene terephthalate substrate was coated at various adhesive coating thicknesses, i.e., 30, 60, 90, and 120 µm using a SHEEN hand coater. A HAAKE Rotary Viscometer Viscosity was used to measure the viscosity of the adhesive. Loop tack and peel strength were determined by a Llyod Adhesion Tester operating at 30 cm/min. Results show that viscosity of the adhesive increases gradually with increase of kaolin loading due to the concentration effect of the filler. Loop tack and peel strength, however, show maximum value at 20 phr and 30 phr kaolin, respectively, an observation which is attributed to the maximum wettability and compatibility of adhesive on the substrate.