Magnetic Recording Medium Polyester Resin Additive Dispersion
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Solution Overview
Problem
Conventional magnetic recording media face challenges in achieving both enhanced durability and dispersion of ferromagnetic powder in the magnetic layer, as excessive polar groups compromise dispersion and increased urethane group concentration in binders improves mechanical properties but decreases solubility and dispersion.
Innovation Solution
A magnetic recording medium with a magnetic layer containing ferromagnetic powder, a binder, a fatty acid ester, and a polyester resin with a number average molecular weight between 1,000 and 20,000, incorporating structural units from polyvalent carboxylic acids and polyols, along with cyclic polyvalent carboxylic acids, and specific partial structures, which enhances dispersion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polar groups are introduced into the binder to enhance dispersion of ferromagnetic powder, then dispersion is improved, but excessive polar groups compromise dispersion
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by incorporating specific polyester resin components with controlled polar group content, balancing dispersion enhancement while preventing excessive polar group accumulation that would compromise dispersion stability
Solution Approach 2:
The invention uses a composite binder system combining polyester resin with specific structural units (including cyclic polyvalent carboxylic acid units) and other components, creating a multi-component system that achieves both good dispersion and stable performance
2Strength
If the concentration of urethane groups in the binder is increased to improve mechanical properties, then durability is improved, but solubility and dispersion decrease
Solution Approach 1:
The invention optimizes the concentration of urethane groups within a specific range (5-50 mol%) rather than maximizing it, balancing mechanical property enhancement with maintaining adequate solubility and dispersion capability
Solution Approach 2:
The invention creates a composite binder system that combines polyester resin with controlled urethane group content alongside other components, achieving synergistic effects that provide both durability and good dispersion
3Duration of action of stationary object
If the concentration of polyurethane groups is increased to enhance mechanical properties of polyurethane resin binder, then durability is improved, but solubility decreases
Solution Approach 1:
The invention controls the polyurethane group concentration within optimal ranges and adjusts the molecular weight and structure of the polyester resin to maintain solubility while achieving desired durability through controlled mechanical property enhancement
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 proposed solution achieves improved dispersion and durability of ferromagnetic powder in the magnetic layer, with the polyester resin contributing to the surface presence of fatty acid ester, forming a protective liquid film that enhances scratch resistance and recording performance.
Implementation Method 1
Polar groups are introduced into the binder to enhance dispersion by causing the binder to effectively adsorb to the surface of the ferromagnetic powder
Implementation Method 2
the polyester resin contributes to the surface presence of fatty acid ester, forming a protective liquid film that enhances scratch resistance
Data Source
AI summary
The magnetic recording medium contains, in a magnetic layer, a fatty acid ester and a polyester resin having a number average molecular weight of greater than or equal to 1,000 but less than 20,000, and containing a structural unit derived from a polyvalent carboxylic acid and a structural unit derived from a polyol, as well as 10 mol % to 50 mol % of a structural unit, derived from a cyclic polyvalent carboxylic acid selected from the group consisting of an alicyclic polyvalent carboxylic acid and an aromatic polyvalent carboxylic acid, per 100 mol % of a combined total of the above structural units, and one or more partial structures selected from the group consisting of the following partial structures:wherein each of L1 and L2 independently denotes a divalent connecting group, and each of Z1 and Z2 independently denotes a monovalent group denoted by —OM or a monovalent group denoted by —O−A+.