Magnetic Recording Medium Thin Nonmagnetic Layer
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Solution Overview
Problem
Magnetic recording media with thin nonmagnetic layers face challenges in achieving both high recording capacity and reliable electromagnetic characteristics and running stability, as reducing the magnetic layer thickness compromises these properties due to abrasive protrusions and increased plastic deformation.
Innovation Solution
A magnetic recording medium with a nonmagnetic layer thickness of 300 nm or less, a composite elastic modulus of 6.0 to 8.0 GPa, and a microparticulate abrasive with a specific surface area of 14 to 40 m2/g, along with controlled surface abrasive occupancy of 0.2 to 2%, is used to enhance electromagnetic characteristics and running stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nonmagnetic layer thickness is reduced to increase recording capacity, then recording capacity is improved, but electromagnetic characteristics and running stability deteriorate
Solution Approach 1:
The invention changes the elastic modulus parameter of the magnetic layer from conventional values to a specific range (6.0-8.0 GPa) to reduce plastic deformation. It also optimizes the abrasive particle size parameter (14-40 m2/g specific surface area) and surface abrasive occupancy (0.2-2%) to prevent head abrasion and maintain electromagnetic characteristics while achieving thin nonmagnetic layer thickness (≤300 nm) for high recording capacity
Solution Approach 2:
The invention uses composite material structures with specific combinations of ferromagnetic powder, binder, and microparticulate abrasive in controlled ratios. The magnetic layer comprises ferromagnetic powder (50-90 wt%), binder (10-40 wt%), and abrasive (0.1-5 wt%), creating a composite that simultaneously provides mechanical compliance, electromagnetic performance, and surface smoothness for high-capacity recording
2Quantity of substance
If the magnetic layer thickness is reduced to increase recording capacity, then recording capacity is improved, but plastic deformation increases compromising running stability
Solution Approach 1:
The invention changes the elastic modulus parameter of the magnetic layer to a specific range (6.0-8.0 GPa) that reduces plastic deformation during calendering. This parameter optimization allows the magnetic layer to maintain its structural integrity and surface smoothness even at reduced thickness, preventing the plastic deformation that would otherwise compromise running stability while enabling higher recording capacity
3Ease of manufacture
If conventional abrasives are used in thin nonmagnetic layers, then manufacturing is simplified, but head abrasion and electromagnetic characteristics deteriorate
Solution Approach 1:
The invention changes the abrasive particle size parameter to a specific range (14-40 m2/g specific surface area) that minimizes head abrasion. It also controls the abrasive concentration parameter (0.1-5 wt% in magnetic layer, 0.2-2% surface occupancy) to prevent electromagnetic characteristic deterioration while maintaining ease of manufacture through standard coating processes
Solution Approach 2:
The invention uses microparticulate abrasive with controlled porosity and surface area (14-40 m2/g) that provides effective surface cleaning and head protection without causing excessive head abrasion. The porous structure of these microparticles allows them to function effectively as abrasives while minimizing harmful effects on electromagnetic characteristics and head durability
Data Source
AI summary
An aspect of the present invention relates to a magnetic recording medium, which comprises a nonmagnetic layer containing a nonmagnetic powder and a binder and a magnetic layer containing a ferromagnetic powder and a binder in this order on a nonmagnetic support, wherein the nonmagnetic layer has a thickness of equal to or less than 300 nm; a composite elastic modulus as measured on a surface of the magnetic layer ranges from 6.0 to 8.0 GPa; the magnetic layer comprises an abrasive with a specific surface area by BET method ranging from 14 m2/g to 40 m2/g; and a surface abrasive occupancy on a surface of the magnetic layer ranges from 0.2% to 2%.