S. Shikama

Perpendicular Magnetic Field Orientation of Acicular Particles: Oblique Orientation with Field Gradient and Viscosity Gradient in Coating

The LIPS (longitudinally oriented inside layer, perpendicularly oriented surface layer) method of film orientation was improved in order to enable preparation of obliquely oriented tapes with a definite orientation angle. The permanent magnet pairs previously used in LIPS perpendicular orientation were replaced by an electromagnet with long iron plates for extension of the magnetic poles. Obliquely oriented tapes are easily prepared by appropriately choosing the coating speed and drying conditions. Coatings dried in a perpendicular magnetic field with an intensity gradient were found to be oriented not perpendicularly, but obliquely. It is thought that inner-layer particles are more easily displaced by the field gradient force than surface particles because of the effect of the viscosity gradient in the coating drying process.

Measurement of Reflection Anisotropy of Polarized Light for Detecting Surface Perpendicular Orientation in MP-LIPS Tape

A rapid, non-destructive optical method for detecting the perpendicular orientation at the surface of metal LIPS tape is described. This technique uses reflection anisotropy due to the depolarization coefficient anisotropy of the acicular metal particles. A tape sample with low anisotropy according to this method of evaluation exhibited higher density wavelength response characteristics.

Recording Characteristics of Obliquely Oriented Particulate Tapes

It has been reported that high-density and wide-bandwidth characteristics may be obtained by using a ring head with obliquely oriented metal evaporated magnetic recording tape. We therefore developed new equipment for the preparation of obliquely oriented tapes based on ¿-Fe2O3 particles, and examined the morphology, magnetic properties, and wavelength response of the tapes. The experimental results showed that tape with an oblique orientation of 30° has the highest output and widest bandwidth characteristics.

Recording Characteristics of LIPS Double-Layered Tape Prepared by Over-Coating

In order to obtain high-density and wide-band recording characteristics, we have tried fabricating double-orientation magnetic tapes, which are longitudinally oriented inside and perpendicularly oriented at the surface (LIPS orientation), using acicular particles in a single coating process, but a LIPS double-orientation structure was not achieved. The purpose of this paper is to describe the recording characteristics of LIPS tapes with an improved double-orientation structure, obtained by coating a longitudinally oriented underlayer with a perpendicularly oriented upper layer. LIPS double-layered tape prepared in this way (with 2.1 ¿m thick upper layer consisting of metal particles with Hc=700 Oe) exhibited a higher output and wider band characteristics than did any of the perpendicular-orientation monolayer tapes and longitudinally oriented double-layer tapes studied, due to its smooth and perpendicularly well-oriented upper layer and the longitudinal orientation in the underlayer.

Magnetic recording characteristics of double-layered LIPS tape prepared by over-coating

In order to obtain the high-density and wideband recording characteristics of a LIPS (oriented longitudinally inside and perpendicularly at surface) magnetic tape, improved LIPS structure tapes are fabricated by overcoating and orienting an upper layer on a longitudinally oriented tape. The metal iron LIPS double-layered tapes, upper layer of 1.1-1.4 mu m in thickness/bottom layer of 1.6 mu m in thickness, show higher output at short wavelengths and almost the same output at long wavelengths as that of the longitudinally well-oriented upper layer and longitudinal orientation in the bottom layer. >

A Particulate Medium Oriented Longitudinally Inside and Perpendicularly at Surface

This report takes another look at the VAST (Vertical magnetic orientation-AC demagnetization-Smoothing period-sequential Train) technique used to fabricate double-layer particulate media oriented longitudinally inside and perpendicularly at the surface from CrO 2 particles and nitrocellulose with a urethane binder. Infrared irradiation was performed to evaporate the solvent instead of natural evaporation to improve the viscosity of the surface perpendicular oriented layer, and to ensure a controlled thin, uniform thickness surface layer.