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US 8,742,058 B2Granted
Biaxially oriented polyester film and linear magnetic recording medium
AssigneeToray Industries, Inc.
InventorsMasato Horie, Takuji Higashioji, Nozomi Yokoyama
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Abstract
A biaxially oriented polyester film has a ratio of Young's modulus in the transverse direction to Young's modulus in the machine direction of 1.5 to 3, an average value of refractive indices in the machine direction, in the transverse direction, and in the thickness direction of 1.590 to 1.680, a minor melting peak temperature of 160 to 190° C., and a coefficient of hygroscopic expansion in the transverse direction of 0 to 6 ppm/% RH.
Claims13
A biaxially oriented polyester film having
- a ratio of Young's modulus in a transverse direction ETD to Young's modulus in a machine direction EMD, ETD/EMD, of 1.5 to 3,
- an n_bar, which represents an average of a refractive index in a machine direction nMD, a refractive index in a transverse direction nTD, and a refractive index in a thickness direction nZD ((nMD+nTD+nZD)/3), of 1.590 to 1.680,
- a minor melting peak temperature T-meta of 160 to 190° C., and
- a coefficient of hygroscopic expansion in the transverse direction of 0 to 6 ppm/% RH, and
- a heat of crystal melting ΔHm of 32 to 45 J/g,
- a degree of crystal orientation in the crystal backbone direction by wide-angle x-ray in the transverse direction of 0.75 to 0.90.
3 more elements
Dependencies are inferred from the claim text.