公开(公告)号：JPH11203659A

公开(公告)日：1999-07-30

申请号：JP29975598

申请日：1998-10-21

Applicant: EMTEC MAGNETICS GMBH

Inventor： WIEGEMANN HANS-BERTRAM ,  STEHLE PETER ,  TRAUB HANSJOERG ,  JAKUSCH HELMUT DR

IPC: G11B5/716 ,  G11B5/73 ,  G11B5/738 ,  G11B5/852 ,  G11B5/704

Abstract: PROBLEM TO BE SOLVED: To provide a general-purpose magnetic recording medium having neither magnetic nor mechanical anisotropy, but being improved in wear resistance and having an excellent mechanical stability at the same time. SOLUTION: This medium is a magnetic recording medium which has at least two layers 9, 8 formed upper and lower, and the lower layer 8 contains acicular magnetic powder having a coercive force of 5-40 kA/m and magnetization of 20-70 nTm /g. While the layers are still in a wet state after they have been formed, they are subjected to a magnetic non-orientation processing of magnetic recording medium, and are made non-isotropic magnetically and mechanically. The magnetic recording medium thus manufactured is suitable for a floppy disk having a high storage capacity exceeding 100 Mbits.

公开(公告)号：DE19747068A1

公开(公告)日：1999-04-29

申请号：DE19747068

申请日：1997-10-24

Applicant: EMTEC MAGNETICS GMBH

Inventor： WIEGEMANN HANS-BERTRAM DR ,  STEHLE PETER ,  TRAUB HANSJOERG DR ,  JAKUSCH HELMUT DR

IPC: G11B5/716 ,  G11B5/73 ,  G11B5/738 ,  G11B5/852 ,  G11B5/68

Abstract: A magnetic recording medium has a lower layer containing an acicular pigment with a coercive field strength of ≤ 40 kA/m and an upper layer containing a ferromagnetic metal powder and is subjected to a magnetic disorientation treatment immediately after coating. A magnetic recording medium consists of a non-magnetic backing coated with a lower layer of an acicular pigment dispersed in a binder and a NOTGREATER 0.4 mu thick upper layer of a ferromagnetic metal powder dispersed in a binder, the novelty being that the pigment in the lower layer has a coercive field strength of ≤ 40 kA/m and that the medium is subjected to a magnetic disorientation treatment in the wet state immediately after layer application. Independent claims are also included for methods of producing the above magnetic recording medium in which (i) the two magnetic layers are passed, in the wet state immediately after application, through a disorientation apparatus consisting of an alignment zone with a constant unipolar magnetic field of direction perpendicular to the backing, a transition zone in which the first zone magnetic field is continued but progressively decreases to NOTGREATER 10 % of the field strength in the first zone, and a field-free non-alignment zone of length such that the magnetic anisotropic pigments in the liquid dispersions spontaneously disorientate; (ii) the disorientation apparatus consists of two alternating magnetic field devices, the first field direction having a higher field strength than the second; or (iii) the disorientation apparatus consists of a first magnetic device in which the anisotropic particles are made perpendicular, followed by a second arrangement of magnetic plates which are located at opposite sides of the backing and which produce a magnetic field acting perpendicularly to the backing so that the field orientation progressively changes by 180 degrees in the coating direction while the field strength decreases.