Magnetic recording medium having a dimensional variation
摘要
說明書
The average thickness tT of the magnetic recording medium 10 is determined in a similar manner to the average value tT for the average thickness tb of the back layer 14.
(Dimensional Change Amount Δw)
The dimensional change amount Δw in the width direction of the magnetic recording medium 10 with respect to the change in the tension in the longitudinal direction of the magnetic recording medium 10 meets the requirement that 700 [ppm/N]≤Δw, preferably 750 [ppm/N]≤Δw, more preferably 800 [ppm/N]≤Δw. When the dimensional change amount Δw is Δw<700 [ppm/N], there is a possibility that it will be difficult to reduce the change in width by the adjustment of the tension in the longitudinal direction with the recording/reproducing device. The upper limit value of the dimensional change amount Δw is not to be considered particularly limited, but for example, Δw≤1700000 [ppm/N], preferably Δw≤20000 [ppm/N], more preferably Δw≤8000 [ppm/N]. The dimensional change amount Δw is set to a desired value, for example, by selecting the thickness of the substrate 11 and the material of the substrate 11. Note that one of the thickness of the substrate 11 and the material of the substrate 11 may be selected, or the both may be selected.
The dimensional change amount Δw is determined as follows. First, the magnetic recording medium 10 with a ?-inch width is prepared, and cut into a length of 250 mm to prepare a sample 10S. Next, a load is applied in the order of 0.2 N, 0.6 N, and 1.0 N in the longitudinal direction of the sample 10S, and the width of the sample 10S is measured at the loads of 0.2 N and 1.0 N. Subsequently, the dimensional change amount Δw is determined from the following formula.
