Mechanism of Chemical Reactions Involved in Magnetic Coatings
The major binders in magnetic coatings are high molecular weight thermoplastic polyurethane and low molecular weight polyisocyanate. This paper reviews the stoichiometry and kinetics of the isocyanate reactions involved in a typical formulation. It was concluded that the dominant reaction is the condensation of the -NCO groups and water in the formulation with the formation of polyurea as an inter-penetrating network in the polyurethane matrix. The degree of crosslinking of the polyurethane molecules was insignificant.
KeywordsMagnetic Tape Frame Durability Melamine Formaldehyde Resin Major Binder Polyurethane Matrix
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