Magnetic Recording Medium Binder Protrusion Control
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Solution Overview
Problem
Magnetic recording media with binders having a glass transition point of 75° C. or higher tend to increase error rates due to surface cracks formed during the calendering process, leading to linear protrusions that can affect data accuracy.
Innovation Solution
A magnetic recording medium with a substrate and a magnetic layer containing magnetic powder and a binder, where atomic force microscope images show no linear protrusions across two sides in four out of five 10 μm×10 μm square observations, ensuring a smooth surface and reduced error rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a binder having a glass transition point Tg of 75° C. or higher is used to improve durability, then the durability is improved, but the error rate becomes higher
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by specifying a particular polyester resin with defined structural characteristics (carboxyl group content, hydroxyl group content, molecular weight range) to achieve the desired balance between durability and error rate performance
Solution Approach 2:
The invention uses a composite binder system consisting of polyester resin combined with specific additives (polyisocyanate, polyester polyol) to create a multi-component formulation that simultaneously provides high glass transition temperature for durability while controlling surface properties to minimize linear protrusions and error rates
2Ease of manufacture
If the temperature of the heating roll is increased to calender the magnetic layer, then the calendering process is improved, but cracks are transferred onto the medium surface forming linear protrusions
Solution Approach 1:
The invention applies preliminary protective action by forming a lubricant layer on the heating roll surface before calendering, and by pre-formulating the magnetic layer with specific binder properties that resist crack formation, thereby preventing defect transfer to the medium surface
Solution Approach 2:
The invention introduces a lubricant layer as an intermediary between the heating roll and the magnetic layer, preventing direct contact and transfer of surface cracks from the heating roll to the medium surface while still allowing effective calendering
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 solution effectively lowers the error rate by preventing the formation of linear protrusions on the medium's surface, enhancing data accuracy and durability.
Implementation Method 1
The glass transition point of the binder is not lower than 75° C.
Implementation Method 2
in a case where atomic force microscope observation images in a 10 μm×10 μm square shape are acquired at five locations randomly selected from the surface on the side of the magnetic layer
Data Source
AI summary
A magnetic recording medium includes: a substrate that is long in shape; and a magnetic layer containing magnetic powder and a binder. The glass transition point of the binder is not lower than 75° C. In a case where atomic force microscope observation images in a 10 μm×10 μm rectangular shape are acquired at five locations randomly selected from the surface on the side of the magnetic layer, any linear protrusion that is 3 nm to 20 nm in height, is 0.3 μm to 1.0 μm in width, and extends across two sides of the observation image does not exist in the observation images of four locations among the acquired observation images of the five locations.