Surface Modification of Magnetic Particles (01-Feb-2010)

Surface Modification of Magnetic Particles

    In the manufacturing of magnetic tape media the dispersing of magnetic nanoparticles is one of the most challenging and crucial aspects. The first step in the manufacturing of magnetic tape is done by kneading the as received magnetic particles with a tape binder in a sealed hopper under dry nitrogen with a suitable solvent; this is the initial dispersion step. Once this is completed, the magnetic particle and binder are thinned with a solvent such as toluene and mixed under very high shear. However, this leads to many problems as the magnetic particle disperses very poorly in toluene, which results in heterogeneous dispersion of the magnetic nanoparticle in the final tape formulation. Additionally, the tape binder/magnetic particle formulation must be consistently mixed to minimize settling of the magnetic particle. This increases the cost of and complicates tape manufacturing.

    The invention works as follows: An organo trialkoxysilane as listed in table 1, is reacted with a mild acid (acetic acid, hydrochloric acid, formic acid) in an aqueous solution to form a

p

 olyalkylsiloxane. This step can be done at ambient temperature or elevated temperatures to increase the reaction kinetics of the polymer formation. Additionally, the solvent used in this step can be tetrahydrofuran, ethanol or methanol. Once...