公开(公告)号：JPS62165726A

公开(公告)日：1987-07-22

申请号：JP748286

申请日：1986-01-17

Applicant: KAO CORP

Inventor： KANNEN NAOMI ,  TSUSHIMA RIKIO ,  YAMASHITA KAZUTAKA ,  OKADA TOMOYUKI

IPC: G11B5/702 ,  C09D5/23 ,  C09D175/00 ,  C09D175/04

Abstract: PURPOSE:To improve the dispersibility of magnetic particles while maintaining the mechanical characteristics which a specific polyurethane resin resin possesses by using said polyurethane resin as a binder for a magnetic recording medium. CONSTITUTION:The polyurethane resin which is produced from the polyketone compd. having at least two hydroxyl groups and expressed by formula I or II as a polyol component is used as the binder for the magnetic recording medium. In formula, n is 1-43 number and m is 1-53 number. The polyketone compd. has preferably 400-6000 number average mol. wt. and more particularly preferably 500-4004000 number average mol. wt. in terms of the flexibility and strong toughness of the resultant polyurethane resin. The number average mol. wt. of the polyurethane resin is 1000-100000, more preferably 5000-50000. The magnetic recording medium is obtd. by providing a magnetic layer formed by dispersing pulverized ferromagnetic powder in such binder on a nonmagnetic base. The specific surface area of the pulverized ferromagnetic powder is preferably /g.