公开(公告)号：GB2266534A

公开(公告)日：1993-11-03

申请号：GB9308837

申请日：1993-04-29

Applicant: BASF MAGNETICS GMBH

Inventor： VASS ATTILA ,  SCHROEER WOLF-DIETER ,  CREDNER HANS-HEINRICH

IPC: G11B5/70 ,  G11B5/712

Abstract: in the preparation of dispersions of magnetic pigments in organic solvents, long-chain dispersants which have a sterically stabilizing effect are precoated on the pigment to give excellent dispersion stability. Subsequently, by the use of charge-generating, low molecular weight codispersants. a charge build-up on the pigment is specifically induced by means of bases or acids. The electrostatic repulsion which additionally becomes effective leads to an increase in the dispersion stability. The charges on the pigment are monitored by means of ESA measurements (electrokinetic sound amplitude). These ESA measurements make it possible to establish the order of addition of the dispersants and the optimum amount of codispersant.

公开(公告)号：GB2266535B

公开(公告)日：1996-03-13

申请号：GB9308838

申请日：1993-04-29

Applicant: BASF MAGNETICS GMBH

Inventor： VASS ATTILA ,  SCHROEER WOLF-DIETER ,  CREDNER HANS-HEINRICH ,  FISCHER HILDEGARD

IPC: G11B5/70 ,  G11B5/712

公开(公告)号：GB2266535A

公开(公告)日：1993-11-03

申请号：GB9308838

申请日：1993-04-29

Applicant: BASF MAGNETICS GMBH

Inventor： VASS ATTILA ,  SCHROEER WOLF-DIETER ,  CREDNER HANS-HEINRICH ,  FISCHER HILDEGARD

IPC: G11B5/70 ,  G11B5/712

Abstract: In the preparation of dispersions of magnetic pigments for magnetic recording media, compounds which are selected from quaternary ammonium compounds, guanidines, piperidines, alkylated or ethoxylated amines, diamines, polyamines or mixtures thereof, ethanolic KOH solutions, metal alkoxylates, Grignard compounds and certain metal hydrides are used as codispersants. The compounds are generally added in an amount of 0.15-4% by weight, based on the magnetic pigment.

公开(公告)号：GB2282338B

公开(公告)日：1997-08-20

申请号：GB9419183

申请日：1994-09-22

Applicant: BASF MAGNETICS GMBH ,  EMTEC MAGNETICS GMBH

Inventor： BRODT GREGOR ,  VASS ATTILA ,  LOCH WERNER ,  LEHNER AUGUST ,  LENZ WERNER ,  SCHNEIDER NORBERT

IPC: C08G18/10 ,  C08G18/62 ,  C08G18/78 ,  C09D5/23 ,  C09D175/00 ,  C09D175/04 ,  G11B5/702 ,  C08L75/04

Abstract: In magnetic recording media consisting of a nonmagnetic substrate and at least one magnetizable layer firmly applied thereon and based on magnetic material dispersed in a binder mixture which contains at least one hydroxyl-containing, preferably low molecular weight polyureaurethane and one polyurethaneurea (meth)acrylate, the polyurethaneurea (meth)acrylate is obtained by reacting a poly(meth)acrylate having up to 2 terminal OH groups per mol and a molecular weight of from 200 to 50,000 with a mixture of aliphatic polyisocyanates having an average functionality of from 3.0 to 6.0 NCO groups per mol, consisting of from 0.1 to 10% by weight of a diisocyanate, from 30 to 80% by weight of a triisocyanate and from 20 to 60% by weight of an isocyanate having a functionality of from 4 to 10, with the proviso that from 1.2 to 3.0 NCO groups react per OH group and the remaining NCO groups are converted into substituted terminal urea groups with a polyfunctional amine or with a mixture of different polyfunctional amines.

公开(公告)号：GB2266534B

公开(公告)日：1996-03-13

申请号：GB9308837

申请日：1993-04-29

Applicant: BASF MAGNETICS GMBH

Inventor： VASS ATTILA ,  SCHROEER WOLF-DIETER ,  CREDNER HANS-HEINRICH

IPC: G11B5/70 ,  G11B5/712

公开(公告)号：GB2282338A

公开(公告)日：1995-04-05

申请号：GB9419183

申请日：1994-09-22

Applicant: BASF MAGNETICS GMBH

Inventor： BRODT GREGOR ,  VASS ATTILA ,  LOCH WERNER ,  LEHNER AUGUST ,  LENZ WERNER ,  SCHNEIDER NORBERT

IPC: C08G18/10 ,  C08G18/62 ,  C08G18/78 ,  C09D5/23 ,  C09D175/00 ,  C09D175/04 ,  G11B5/702 ,  C08L75/04

Abstract: A magnetic recording medium comprises a nonmagnetic substrate and at least one magnetizable layer firmly applied thereon and based on a magnetic material dispersed in a binder mixture which contains at least one hydroxyl-containing, preferably low molecular weight, polyureaurethane and at least one polyurethane-urea (meth)acrylate. The polyurethane-urea (meth)acrylate is obtained by reacting a poly(meth)acrylate having up to 2 terminal OH groups per mol and a molecular weight of from 200 to 50,000 with a mixture of aliphatic polyisocyanates having an average functionality of from 3.0 to 6.0 NCO groups per mol. The mixture comprises from 0.1 to 10% by weight of a diisocyante, from 30 to 80% by weight of a triisocyanate, and from 20 to 60% by weight of an isocyanate having a functionality of from 4 to 10. From 1.2 to 3.0 NCO groups react per OH group and the remaining NCO groups are converted into substituted terminal urea groups with a polyfunctional amine or with a mixture of two or more different polyfunctional amines.