Reactivity of Cross-linking Reactions Observed in PSA and Correlation between Molecular Mobility and Adhesion Performance Investigated by NMR Spectroscopy

Abstract

Acrylate copolymers, which are one of the main components of acrylic pressure-sensitive adhesives (PSA), in general have extremely high degree of freedom on material design because they are the combination of various different acrylic monomers. Some of fundamental characteristics of PSA such as cohesiveness, tackiness or adhesion is possibly controlled by both of the amount of functional groups introduced in the copolymer and the amount of cross-linking agents (e.g. multifunctional isocyanates) added into the PSA.Isocyanate group in cross-linking agents inevitably react not only to hydroxyl group of copolymer side chains but also to water residual in a solvent and moisture in atmosphere, and it has been making estimation of precise reaction rate of isocyanate and hydroxyl groups complicated. Here we report our study of correlation between molecular mobility and adhesion performance investigated by NMR spectroscopy, which unveils reactivity of cross-linking reactions observed in PSA further in detail.