Effects of monomers on the properties of palm-oil-based radiation curable pressure sensitive adhesives (PSA) - a prepolymer method

Various low glass transition temperature (T-g) acrylate and methacrylate mo nomers were mixed with epoxidised palm oil acrylate (EPOLA) with the ratio of 50/50 prior to curing with electron beam (EB) irradiation. Methacrylate monomers such as dicyclopentenyloxyethyl methacrylate (DCPOEMA) and isoborn yl methacrylate (ISBMA), although displaying relatively high adhesive prope rties were finally excluded from being further utilised as monomers for PSA because of a very slow curing speed. Literally, it is suggested that poore r adhesive performances of the cured films made from 50/50 : EPOLA/monomer mixture as compared to that of 100% monomer was attributed to the lack of c ompatibility between EPOLA and the particular monomers. Further compatibili ty investigations were continued using formulations prepared via the prepol ymer route cured by ultraviolet (UV) irradiation and the results showed tha t several monoacrylate monomers with polar and non-polar groups exhibited h igh curing speed as well as good compatibility with EPOLA as shown by their cured film properties such as surface tackiness, peel adhesion and creep r esistance. It is also suggested that these monomers were acting as surfacta nts for EPOLA which consequently enhance their compatibility upon mixing. ( C) 2001 Elsevier Science Ltd. All rights reserved.