Pressure-sensitive adhesives (PSAs), which date back to the 1920s, are critical to the medical, engineering and construction industries. Demand for PSA tape in 2017 was 39.2 billion sq m4 and was expected to rise to 50 billion sq m by the end of 2018. PSA manufacturers continue research efforts to invent novel materials that are required to meet both customer demand and new applications.
The application quality of a PSA is determined by three main properties: tack, peel strength (adhesion) and shear strength (cohesion).1-2 Various blends of reactant monomers such as acrylic acid and 2-ethylhexyl acrylate (2EHA) have been introduced into reaction systems to tailor the physical properties of PSAs. The results of these chemistry and reactant changes are observed in the reaction kinetics, molecular weight (Mw), and intrinsic viscosity (IV), which vary by formulation. Conventional, off-line analysis on an end product makes manufacturing and QC complicated and time consuming, with a lack of systematic consistency. Introducing continuous, online monitoring of these characteristics leads to better quality and reaction process optimization, improving the R&D cycle and increasing manufacturing efficiency.