LIFETIME EXPECTANCY OF POLYURETHANE BINDER AS MAGNETIC RECORDING MEDIA

The effects of the chemical structure and addition of cross-linking ag ent and polyvinyl chloride (PVC) on the tensile strength of polyuretha nes (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 respon sible 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 ext ends the lifetime of PU binder. For example, poly(hexamethylene carbon ate) diol-based polyurethane PU(PCD) in a mixture system such as PU(PC D)/CL/PVD can be expected to have a tensile half life of about 200 yea rs at 20 degrees C.