Shrinkage studies in electron beam curable polyurethane pressure-sensitive adhesive

Abstract

Polyurethane (PU)-based pressure-sensitive adhesive (PSA) has been manufactured by electron beam (e-beam) irradiation using urethane-acrylate. The effect of variation of e-beam dose and crosslinkers viz. triallyl cyanurate (TAC), triallyl isocyanurate, polymeric methylene diphenyl diisocyanate, carbodiimide-modified methylene diphenyl di-isocyanate, methylene diphenyl di-isocyanate, and isophorone di-isocyanate (IPDI) has been studied concerning the shrinkage, adhesion properties, and gel content of the PU-PSA. It was found that with increasing e-beam dose the shrinkage is increased up to 25 kGy, but remained constant thereafter with further increasing the dose up to 60 kGy. Similarly, with increasing concentration of crosslinkers from 2 to 6%, shrinkage is increased but beyond that there is no appreciable change. A comparative study of the effect of different crosslinkers on shrinkage, adhesion properties, and gel content of PU-PSA was carried out, and it was found that TAC leads to the maximum, while IPDI to the lowest shrinkage. However, the opposite was observed for the adhesion properties, i.e. the use of IPDI ensures the maximum and of TAC, the minimum adhesive performance characteristics.