Magnetic Recording Medium Composite Binder Durability
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Solution Overview
Problem
Conventional magnetic recording media face challenges in achieving enhanced durability and dispersion of ferromagnetic powder, as improving mechanical properties of the binder leads to decreased powder dispersion, and high urethane group concentrations compromise solubility and dispersion.
Innovation Solution
Incorporating a compound denoted by Formula (1), which includes a polyester chain and carboxyl (salt) groups, into the magnetic layer to enhance durability and dispersion by providing a suitable elongation tendency and steric hindrance effect, preventing powder aggregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mechanical properties of the binder are enhanced to improve durability of the magnetic layer, then the durability is improved, but the dispersion of ferromagnetic powder decreases
Solution Approach 1:
The invention uses a composite binder system comprising both polyurethane resin and polyester resin. The polyurethane resin provides mechanical strength and durability, while the polyester resin with carboxyl groups maintains powder dispersion. This composite approach allows both contradictory requirements to be satisfied simultaneously.
Solution Approach 2:
The invention specifies precise compositional parameters: polyurethane resin content at 30-70 wt% and polyester resin content at 70-30 wt%, with carboxyl group concentration of 0.1-5.0 mmol/g. By controlling these parameters within specific ranges, the invention optimizes both durability and dispersion properties.
2Strength
If the concentration of urethane groups in the binder is increased to enhance mechanical properties, then the mechanical properties are improved, but the solubility decreases leading to reduced powder dispersion
Solution Approach 1:
The invention controls the urethane group concentration within specific ranges (0.5-5.0 mmol/g for polyurethane resin) to balance mechanical properties and solubility. Simultaneously, it introduces carboxyl groups (0.1-5.0 mmol/g) to enhance dispersion without compromising solubility.
Solution Approach 2:
The composite binder system allows the polyurethane resin to provide mechanical strength through urethane groups while the polyester resin with carboxyl groups maintains solubility and dispersion. The synergistic combination resolves the contradiction between strength and solubility.
3Stability of the object's composition
If polar groups are introduced into the binder to enhance dispersion of ferromagnetic powder, then the dispersion is improved, but excessive polar groups cause dispersion to decrease
Solution Approach 1:
The invention introduces carboxyl groups with a controlled concentration of 0.1-5.0 mmol/g into the polyester resin. This specific concentration range provides sufficient polar interaction for powder dispersion while avoiding excessive polarity that would cause aggregation.
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 compound achieves improved dispersion and durability of the magnetic layer, maintaining high recording density and stability while resisting scratches and wear.
Implementation Method 1
The polar groups can be introduced into the binder to increase dispersion by causing the binder to efficiently adsorb to the surface of the ferromagnetic powder
Data Source
AI summary
The magnetic recording medium comprises a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, and further comprises a compound denoted by Formula (1):wherein, in Formula (1), X denotes —O—, —S—, or NR1—; each of R and R1 independently denotes a hydrogen atom or a monovalent substituent; L denotes a divalent connecting group; Z denotes a partial structure of valence n comprising at least one group selected from the group consisting of carboxyl groups and carboxylate groups; m denotes an integer of greater than or equal to 2, and n denotes an integer of greater than or equal to 1.