Polyurethanes with thin-film adhesives

As was found for electrochemical-based sensors, problems can occur with peeling of the membrane element from its substrate. PVC is not the only membrane used for optrodes other polymers include polyurethane, which displayed improved adhesion [125]. Ambrose and Meyerhoff [126] incorporated ion-selective species into thin liquid films of decyl methacrylate on glass and then photopolymerised the methacrylate, with simultaneous crosslinking and covalent attachment of the polymer to its substrate to give substantially improved lifetimes. 

Polyurethane bulk and thin-film samples are prepared from a two-part PU adhesive formed by polyaddition of Bayer Desmodur CD (89% diphenylmethane-4,4 -diisocyanate 1 with 11% uretoneimine triisocyanate 2 as additive) with a polyol mixture of Bayer Desmophen 2060BD (linear poly(propylene ether) diol... 

In some modem curtain coaters, the top tank is a small volume chamber equipped with a rotating double knife. It may apply a thin film of adhesive, with reduced entrapment of air and an electronic control of thickness. With this closed application system there is no evaporation of solvents, it may work with both solvent based or water based adhesives and even the moisture curing polyurethanes. 

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