公开(公告)号：JPH11310736A

公开(公告)日：1999-11-09

申请号：JP31556898

申请日：1998-11-06

Applicant: EMTEC MAGNETICS GMBH

Inventor： SCHUENEMANN AXEL ,  ZETTLER HANS-DIETER ,  NAGEL PETER

IPC: G11B5/70 ,  B01F3/14 ,  B01F3/18 ,  B01F5/06 ,  B01F7/04 ,  B01F7/06 ,  B01F11/00 ,  B05D5/12 ,  B29B7/40 ,  B29B9/00 ,  B32B3/02 ,  C09D5/23 ,  G11B5/68 ,  G11B5/84 ,  G11B5/842

Abstract: PROBLEM TO BE SOLVED: To provide a process by which a relatively large quantity of a magnetic dispersion can be economically prepared and a magnetic coating having good magnetic values and magnetic characteristics can be realized. SOLUTION: This process consists of producing a magnetic dispersion for a magnetic-particle-containing magnetic coating having a coercive force of above 120 kA/m, a relative remanence induction Mr/Mn of at least about 0.9, and an orientation rate of at least 2.7 by means of a single axis blade type kneader having a shaft (W) which revolves within a machine frame having a machine frame wall (K), simultaneously vibrates in the axial direction, and has the function of kneading a thermoplastic resin binder and a magnetic particle mixture in a solvent, wherein (a) the radial shear gradient in the gap (s) between the tip of the kneading blade and the machine frame wall (K) is about 150 to about 1,600, particularly, about 500 to about 1,400 1/sec, and (b) the peripheral speed of the kneading blade is about 20 to about 80, particularly, about 35 to about 60 cm/sec. The thus produced magnetic dispersion can be used to produce an information recording medium and an image recording medium having a particularly high recording and memory speed.

公开(公告)号：DE19749315A1

公开(公告)日：1999-05-12

申请号：DE19749315

申请日：1997-11-07

Applicant: EMTEC MAGNETICS GMBH

Inventor： SCHUENEMANN AXEL ,  ZETTLER HANS-DIETER ,  NAGEL PETER

IPC: G11B5/70 ,  B01F23/57 ,  B01F27/71 ,  B05D5/12 ,  B29B7/40 ,  B29B9/00 ,  B32B3/02 ,  C09D5/23 ,  G11B5/68 ,  G11B5/84 ,  G11B5/842 ,  B01F3/14 ,  B01F7/06

Abstract: A magnetic coating dispersion is produced in a single shaft vane mixer with a rotating and axially oscillating shaft, in which the radial shear gradient, in the gap between the vane tips and the mixer housing wall, is 150-1600 1/s and the peripheral velocity of the vanes is 20-80 cm/s. A magnetic coating dispersion, containing magnetic particles of greater than 120 kA/m coercive field strength, ≥ 0.9 relative magnetic remanence (Mr/Mm) and ≥ 2.7 directionality factor, is produced in a single shaft vane mixer with a rotating and axially oscillating shaft for kneading a mixture of magnetic particles in a thermoplastic binder and a solvent, the novelty being that the radial shear gradient, in the gap between the vane tips and the mixer housing wall, is 150-1600 (especially 500-1400) 1/sec. and the peripheral velocity of the vanes is 20-80 (especially 35-60) cm/sec. Independent claims are also included for (i) use of the single shaft vane mixer, described above, in the above process; and (ii) a magnetic recording medium with a magnetic coating which is produced by the above process and which has a coercive field strength of ≥ 130 kA/m, relative magnetic remanence (Mr/Mm) of 0.9-0.92, a directionality factor about 2.7 and, after calender smoothing at 70 degrees C and 2350 N, a signal/noise ratio of greater than 2 dB, a 3.5 MHz signal reproduction value of +1.0 to 1.7 dB and a 35.5 MHz signal reproduction value of greater than -2 dB, the deviation measurements (dB) being with respect to the metal pigment reference magnetic tape C1A-DB of the Sony Corporation.