Synthesis and Optimization of a Four-component Acrylic-based Copolymer as Pressure Sensitive Adhesive

Abstract

pressure sensitive adhesive (PSA) based on acrylic monomers was synthe- sized. For this purpose a solution copolymerization process was conducted for preparation of an acrylic copolymer containing 2-ethylhexylacrylate (2-EHA), 2- hydroxyethyl acrylate (2-HEA), glycidyl methacrylate (GMA) and vinyl acetate (VAc), using 2,2'-azobisisobutyronitrile (AIBN) as an initiator. The initial amounts of feed monomers were constant in all formulations (2-EHA/VAc/ HEA/GMA; 67%, 28%, 4.9%, 0.1% by weights). With variation of different parametric conditions such as reaction times (3.5, 6.5 and 9.5 h), temperatures (70, 80 and 90°C) and initiator concentrations (0.25, 0.5 and 1 wt%) the copolymerization reactions were optimized. The adhesive properties have been evaluated in terms of intrinsic viscosity, glass transition temperature (T g ), peel strength and tack value for all samples. It was observed that the trends in peel strength and intrinsic viscosity variations are approximately correlated with the above changing parameters. The synthesized PSAs show good adhesive properties and could be easily peeled off from the surface without leaving any residue on the surface. These samples with satisfactory adhesion properties were characterized by Fourier transform infrared, proton nuclear magnetic resonance spectroscopy, differential scanning calorimetry and gel permeation chromatography. Based on the optimum time (3.5 h), temperature (70°C) and initiator concentration (0.5 wt%), a formulation with the best adhesion properties and high conversion (86%) was selected as the optimized PSA and it was compared with a commercialized PSA namely Duro-Tak 2287.