Non-magnetic undercoating layer for magnetic recording medium, magnetic recording medium and non-magnetic particles
US5830557A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 22, 1995 |
| Grant date | Nov 3, 1998 |
| Priority date | — |
| Expiry date | Feb 22, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2995
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The disclosure describes a non-magnetic undercoating layer for a magnetic recording medium, coated on the surface of a non-magnetic substrate comprising: PA1 non-magnetic particles selected from the group consisting of particles (1) and (2): PA2 (1) coated acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles which are produced by adhering not less than 0.01 to 20 wt % (calculated as Al, SiO.sub.2 or Al and SiO.sub.2, and based on acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles as a core material) of an oxide or a hydroxide containing Al, Si or both Al and Si to the surfaces of acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles as a core material, and have a molecular weight-dependent parameter .alpha. represented by the following formula of not less than 0.5: EQU As=K.sub.1 .multidot.M.sup..alpha. PA2 wherein M represents the number-average molecular weight of a binder resin, As represents the saturation adsorption of said binder resin, and K.sub.1 represents a constant used for measuring As and dependent on the binder resin and a solvent, PA2 (2) BaO.multidot.4.5Fe.sub.2 O.sub.3 particles having an average particle diameter of not more than 0.1 .m…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.