Magnetic Recording Medium Nonmagnetic Powder Particle Size Control
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Solution Overview
Problem
Conventional magnetic recording media face a tradeoff between achieving good electromagnetic characteristics and frictional characteristics, as controlling the surface contour of the magnetic layer to enhance frictional characteristics often compromises electromagnetic characteristics, and vice versa.
Innovation Solution
A magnetic recording medium is developed with a nonmagnetic layer and a magnetic layer on a nonmagnetic support, where the nonmagnetic powder in the magnetic layer has a coefficient of variation in particle size distribution less than 20%, an average particle diameter between 0.10 to 0.20 μm, and a thickness of the magnetic layer equal to or less than 0.1 μm, optimized to balance both electromagnetic and frictional characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the surface contour of the magnetic layer is controlled by adjusting the type and quantity of nonmagnetic filler to enhance frictional characteristics, then the coefficient of friction decreases, but the electromagnetic characteristics deteriorate due to increased spacing between the head and medium surface
Solution Approach 1:
The patent applies parameter changes by precisely controlling the average particle diameter (0.05-0.5 μm) and particle size distribution (standard deviation 0.03-0.15 μm) of nonmagnetic filler particles, along with optimizing the magnetic layer thickness (0.05-0.2 μm). These parameter optimizations enable the nonmagnetic filler to provide adequate surface protrusions for friction reduction while maintaining sufficient contact area for electromagnetic signal transmission, thus resolving the contradiction between frictional and electromagnetic characteristics
Solution Approach 2:
The patent applies local quality by creating a differentiated surface structure where nonmagnetic filler particles are distributed throughout the magnetic layer, with smaller particles (0.05-0.2 μm) providing surface protrusions for friction control and larger particles (0.2-0.5 μm) maintaining electromagnetic contact. This local differentiation of particle sizes and functions within the same layer allows simultaneous optimization of both frictional and electromagnetic characteristics
2Productivity
If microparticulate magnetic materials are highly dispersed in the magnetic layer to achieve high-density recording, then surface smoothness increases, but the coefficient of friction increases resulting in decreased running durability
Solution Approach 1:
The patent applies composite materials by combining microparticulate magnetic materials with nonmagnetic filler particles of specific size ranges in the magnetic layer. The magnetic particles enable high-density recording through fine dispersion, while the nonmagnetic filler particles (0.05-0.5 μm) create surface protrusions that reduce friction and enhance running durability. This composite structure allows simultaneous achievement of high-density recording and improved running durability
Solution Approach 2:
The patent applies parameter changes by optimizing the concentration ratios of magnetic particles to nonmagnetic filler particles, controlling the average particle diameter and size distribution of both components. These parameter optimizations ensure that the magnetic layer maintains high magnetic particle density for high-density recording while the nonmagnetic filler provides adequate surface protrusions to reduce friction and improve running durability
Data Source
AI summary
An aspect of the present invention relates to a magnetic recording medium comprising 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, whereinthe magnetic layer comprises a nonmagnetic powder of which coefficient of variation CV of a particle size distribution as denoted by the following formula (1):CV(%)=σ/φ×100 (1)is less than 20 percent, andthe magnetic layer has a thickness being equal to or less than 0.1 μm and falling within a range of 1.1≦φ/t≦8.0, wherein σ denotes a standard deviation of a particle diameter, φ denotes an average particle diameter of the nonmagnetic powder comprised in the magnetic layer being expressed in μm, and t denotes a thickness of the magnetic layer being expressed in μm.