| 摘要 |
PURPOSE:To manufacture a magnetic recording medium having excellent smoothness, electromagnetic transducing characteristic and durability by removing the oligomer incorporated into a base plate to be used as a base body for a magnetic recording medium prior to formation of said medium. CONSTITUTION:A base plate consisting of a high polymer molding which is a base body of a magnetic recording medium is heat-treated at the melting, sublimating or decomposing temp. thereof or below and the oligomer deposited on the surface of the base body is removed and thereafter a magnetic layer is formed thereto to manufacture the magnetic recording medium having high smoothness. Oligomer having a low mol.wt. is incorporated at 3-4% in addition to a polymer in commercially marketed PET1. When the PET1 is heat-treated, for example, in the atm. for 2hr at 180 deg.C, the size of the oligomer increases as large as 1 micron height and 3 micron width in average. The height and width of the oligomer 3 change largely with the heat-treating temp. of the m.p. of the PET (about 220 deg.C) or below and the treating time. The oligomer is removed by a method of washing away the oligomer by a solvent or passing the same in a steam bath.
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