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Pressure Sensitive Polyurethane Adhesives

Relatively little information has been published on the kinetics of high 2,4 MDI. To provide a better understanding of the relative reaction rates of the isocyanate group, model compounds were synthesized and used for the high 2,4 MDI based prepolymers. Physical characterization of the model compounds and the relative kinetics will be presented. This paper will focus on prepolymers and sealants based on TDI, MDI, and high 2,4 MDI. The sealants were characterized by general physical property data (tensile elongation, 100 and 300% modulus, and hardness), tack free times, shelf stability, and joint movement capability testing. DMTA data will be used to help explain performance differences observed. This work demonstrates that high 2,4 MDI based prepolymers can be used to replace TDI based prepolymers in commercial sealant formulations, reducing the handling concerns of TDI based formulations.