| 摘要 |
In manufacturing of a magnetic recording medium by using an extrusion-type coating method of extruding a coating liquid from an end of a slit of a coating head and applying the coating liquid to a continuously-running flexible support while making the flexible support relatively approach the end of the coating head so as to apply a magnetic coating liquid obtained by dispersing magnetic particles in a solvent on the flexible support to form a magnetic-coating-liquid layer, the quality of the coating condition is evaluated in accordance with shearing energy E for unit volume of the magnetic-coating-liquid layer obtained by <math-cwu id="MATH-US-00001"> <NUMBER>1</NUMBER> <MATH> <MROW> <MROW> <MI>E</MI> <MO>=</MO> <MFRAC> <MROW> <MI>mu</MI> <MO>·</MO> <MI>L</MI> <MO>·</MO> <MI>V</MI> </MROW> <MROW> <MN>4</MN> <MO>·</MO> <MSUP> <MI>t</MI> <MN>2</MN> </MSUP> </MROW> </MFRAC> </MROW> <MO>,</MO> </MROW> </MATH> <mathematica-file id="MATHEMATICA-00001" file="US20050019482A1-20050127-M00001.NB"/> <image id="EMI-M00001" wi="216.027" he="17.03835" file="US20050019482A1-20050127-M00001.TIF" imf="TIFF" ti="MF"/> </MATH-CWU> where mu is viscosity (Pa.sec) of the magnetic coating liquid at shearing velocity of 10<5 >sec<-1>, L is length (m) of a flexible support opposite face at downstream side of the slit at the end of the coating head, V is running velocity (m/sec) of the flexible support, and t is wet-coating thickness (m) of the magnetic-coating-liquid layer. Then, the coating condition is decided in accordance with the evaluation result. It is thus possible to suppress and break coagulation of the magnetic particles in the magnetic coating liquid, so that a preferable magnetic-layer surface can be obtained.
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