Magnetic Recording Medium High Anisotropy Surface Roughness
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Solution Overview
Problem
Magnetic recording media with high anisotropic magnetic fields tend to have deteriorated electromagnetic conversion characteristics due to reduced magnetization, and achieving high recording density is challenging while maintaining smooth surface interactions with magnetic heads.
Innovation Solution
A magnetic recording medium with a non-magnetic support and a magnetic layer containing ferromagnetic powder, featuring an anisotropic magnetic field of 12 kOe or more, a surface roughness of 1.2 nm or less, and a specific contact angle ratio after immersion in 1,1,1,2,2,3,4,5,5-decafluoropentane, which includes a fluorine-containing compound to enhance lubrication and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the anisotropic magnetic field Hk is increased to improve recording density, then the magnetic layer becomes less likely to be magnetized, but electromagnetic conversion characteristics deteriorate
Solution Approach 1:
The invention changes the surface roughness parameter (Ra ≤ 1.2 nm) and surface chemistry parameters (contact angle ratio θr ≤ 0.95 after fluorocarbon oil immersion) to optimize the interface between magnetic layer and magnetic head. This allows achieving high recording density with Hk ≥ 12 kOe while maintaining good electromagnetic conversion characteristics through controlled surface properties rather than simply reducing Hk
Solution Approach 2:
The invention uses a composite approach by combining high Hk magnetic powder materials with a specifically engineered surface layer having controlled roughness and fluorocarbon compound coating. This composite structure allows the bulk magnetic layer to provide high recording density while the surface layer ensures good electromagnetic conversion by reducing friction and improving magnetic head contact
2Reliability
If the surface roughness is reduced to improve electromagnetic conversion characteristics, then surface smoothness increases, but manufacturing complexity increases
Solution Approach 1:
The invention applies preliminary surface treatment during the magnetic layer formation process itself, incorporating surface smoothing and fluorocarbon compound application as integral parts of the coating process. This preliminary action achieves Ra ≤ 1.2 nm and proper contact angle ratio without requiring complex post-processing steps
Solution Approach 2:
The magnetic layer formulation is designed to self-smooth during the coating and drying process, achieving the required surface roughness (Ra ≤ 1.2 nm) through the inherent properties of the magnetic powder suspension and drying kinetics, eliminating the need for separate mechanical polishing or complex surface treatment equipment
3Ease of operation
If fluorine-containing compounds are added to reduce friction and improve surface properties, then lubrication increases, but manufacturing process complexity increases
Solution Approach 1:
The invention merges the fluorocarbon compound application with the magnetic layer coating process itself. The fluorocarbon-containing compound is incorporated into the magnetic layer formulation or applied as an overcoat in the same processing line, achieving surface lubrication (contact angle ratio θr ≤ 0.95) without adding separate lubrication steps or equipment
Solution Approach 2:
The invention changes the chemical composition parameter of the surface layer by incorporating fluorocarbon compounds with specific molecular structures (as defined in Formula 1 of the patent). This chemical parameter change provides the desired lubrication properties and surface energy characteristics while maintaining a simple single-step coating process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The medium exhibits excellent electromagnetic conversion characteristics by balancing high anisotropic magnetic fields with smooth surface interactions, improving recording density and reducing noise and friction-related issues.
Implementation Method 1
a magnetic layer including a ferromagnetic powder
Implementation Method 2
electromagnetic conversion characteristics
Implementation Method 3
a ratio θr of a contact angle θ2 with respect to 1-bromonaphthalene, measured on a surface on the magnetic layer side after a 1,1,1,2,2,3,4,5,5,5-decafluoropentane immersion
Implementation Method 4
improve lubrication and reduce friction
Data Source
AI summary
The magnetic recording medium includes a non-magnetic support, and a magnetic layer including a ferromagnetic powder. An anisotropic magnetic field Hk is 12 kOe or more, a center line average roughness Ra of the surface of the magnetic recording medium on the magnetic layer side is 1.2 nm or less, and a ratio θr of a contact angle θ2 with respect to 1-bromonaphthalene, measured on a surface on the magnetic layer side after a 1,1,1,2,2,3,4,5,5,5-decafluoropentane immersion, to a contact angle θ1 with respect to 1-bromonaphthalene, measured on the surface on the magnetic layer side before the 1,1,1,2,2,3,4,5,5,5-decafluoropentane immersion is 0.95 or less.