The effects of the chemical structure and addition of cross-linking agent and polyvinyl chloride (PVC) on the tensile strength of polyurethanes (PU) binder have been investigated. An expectation of the lifetime of PU binder as magnetic recording media has been performed based on the tensile strength change in different environmental conditions.
It was found that a small number of ester bonds which are directly responsible for the polymer degradation and suitable storage temperature are required to extend the lifetime of the recording media. In addition, the presence of PVC and polyisocyanate (CL) as cross linking agent extends the lifetime of PU binder. For example, poly(hexamethylene carbonate) diol-based polyurethane PU(PCD) in a mixture system such as PU(PCD)/CL/PVD can be expected to have a tensile half life of about 200 years at 20°C.
