Crosslinkable Polyester Binder for Magnetic Recording Media
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Solution Overview
Problem
Conventional magnetic recording media face challenges in achieving both enhanced dispersion of ferromagnetic powder and increased durability of the magnetic layer, as improving mechanical properties of the binder to enhance durability leads to decreased powder dispersion.
Innovation Solution
A magnetic recording medium composition incorporating a crosslinkable polyester with a weight average molecular weight between 1,000 to 20,000, containing acidic groups and reactive groups capable of forming crosslinking structures through radical, ionic, or pericyclic reactions, which adsorbs to ferromagnetic powder surfaces and provides extensibility and plasticizing effects to improve dispersion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the concentration of polyurethane groups is increased to enhance mechanical properties of the binder, then the durability of the magnetic layer is improved, but the solubility decreases and dispersion of ferromagnetic powder decreases
Solution Approach 1:
The patent introduces a specific parameter constraint on the polyurethane group concentration, limiting it to 5-50 mol% rather than using higher concentrations that would improve mechanical properties. This parameter optimization resolves the contradiction by finding the optimal balance point where both mechanical properties and dispersion are adequate.
Solution Approach 2:
The patent uses a composite binder system combining polyurethane resin with polyester resin and carboxylic acid-modified polyester resin. This composite approach allows the system to achieve both good mechanical properties and adequate dispersion, as each component contributes different properties that complement each other.
2Quantity of substance
If polar groups are introduced into the binder to enhance dispersion of ferromagnetic powder, then the binder can effectively adsorb to the surface of ferromagnetic powder, but excessive quantity of polar groups compromises dispersion
Solution Approach 1:
The patent introduces a specific parameter constraint on the carboxylic acid group content, limiting it to 0.1-10 mmol/g. This parameter optimization resolves the contradiction by finding the optimal balance point where polar groups provide adequate adsorption for dispersion without excessive quantity that would compromise dispersion quality.
3Manufacturing precision
If the particle size of ferromagnetic powder is reduced to increase recording density, then higher performance is achieved, but the magnetic force per bit decreases and the surface becomes more prone to scratching
Solution Approach 1:
The patent uses a composite binder system combining polyurethane resin, polyester resin, and carboxylic acid-modified polyester resin. This composite approach enhances the durability of the magnetic layer to compensate for the reduced mechanical strength caused by smaller particle sizes, while maintaining high recording density.
Solution Approach 2:
The patent introduces carboxylic acid-modified polyester resin specifically to enhance durability at the surface level where scratching occurs, while the bulk composition maintains the properties needed for high recording density with fine particles.
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 composition achieves improved dispersion and durability of the magnetic layer, maintaining high recording density and electromagnetic characteristics while preventing surface scratching.
Implementation Method 1
the crosslinkable component contains at least polyester... which adsorbs to ferromagnetic powder surfaces
Implementation Method 2
a component capable of forming a crosslinking structure by a radical reaction
Implementation Method 3
a component capable of forming a crosslinking structure by an ionic reaction
Implementation Method 4
a component capable of forming a crosslinking structure by a pericyclic reaction
Data Source
AI summary
The magnetic recording medium composition contains ferromagnetic powder, binder, and a crosslinkable component selected from the group consisting of a component capable of forming a crosslinking structure by a radical reaction, a component capable of forming a crosslinking structure by an ionic reaction, and a component capable of forming a crosslinking structure by a pericyclic reaction, wherein the crosslinkable component contains at least polyester, and the polyester has a weight average molecular weight ranging from 1,000 to 20,000, as well as contains, per molecule, one or more acidic groups, and one or more reactive groups selected from the group consisting of a radical reactive group, an ionic reactive group, and a pericyclic reactive group.