Polishing Composition for Magnetic Disk Substrate Scratch Reduction
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Solution Overview
Problem
Conventional polishing compositions for magnetic disk substrates fail to adequately reduce scratches and maintain polishing efficiency over multiple polishing cycles, leading to reduced productivity due to contamination and aggregation issues with colloidal silica and chemical components.
Innovation Solution
A polishing composition comprising colloidal silica, a water-soluble polymer compound with a specific molecular weight range and molar ratio of unsaturated aliphatic carboxylic acid and unsaturated amide units, and organic phosphonic acid, along with a surfactant having sulfonic acid and aromatic groups, is used to improve polishing efficiency and reduce scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If colloidal silica and chemical components are mixed immediately before polishing, then scratch reduction is achieved, but colloidal silica aggregation occurs and polishing rate decreases after multiple uses
Solution Approach 1:
The patent applies preliminary action by preparing the polishing composition in advance with colloidal silica and chemical components mixed together, rather than mixing them immediately before polishing. The composition is prepared with specific concentrations (colloidal silica: 1-50% by mass, chemical component: 0.01-10% by mass) and allowed to stand for a predetermined period before use, which prevents aggregation and maintains polishing effectiveness over multiple uses.
Solution Approach 2:
The patent applies parameter changes by optimizing the concentration ratios of colloidal silica (1-50% by mass) and chemical components (0.01-10% by mass), controlling particle size distribution (D50: 0.01-10 μm), and adjusting pH value (2-10) to achieve both scratch reduction and sustained polishing rate without aggregation.
2Productivity
If colloidal silica concentration is increased to improve polishing rate, then productivity increases, but scratch reduction capability decreases
Solution Approach 1:
The patent applies parameter changes by establishing optimal concentration ranges for colloidal silica (1-50% by mass) and chemical components (0.01-10% by mass), along with controlling particle size distribution (D50: 0.01-10 μm) and pH value (2-10), to achieve both high polishing rate and effective scratch reduction simultaneously.
Solution Approach 2:
The patent applies composite materials by creating a polishing composition that combines colloidal silica particles with specific chemical components in optimized ratios, where the synergistic interaction between the abrasive particles and chemical agents achieves both mechanical polishing (high rate) and chemical polishing (scratch reduction) effects.
3Manufacturing precision
If chemical component concentration is increased to enhance scratch reduction, then manufacturing precision improves, but colloidal silica aggregation increases and polishing rate decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration of chemical components to 0.01-10% by mass, which is sufficient for scratch reduction without causing excessive aggregation of colloidal silica, thereby maintaining acceptable polishing rates.
Solution Approach 2:
The patent applies local quality by having different components perform specialized functions: colloidal silica particles (0.01-10 μm D50) provide mechanical polishing and scratch removal, while chemical components provide controlled chemical etching for scratch reduction, with each component optimized at its optimal concentration to avoid interfering with the other's effectiveness.
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 effectively reduces scratches and maintains polishing rate stability over multiple cycles, enhancing productivity by balancing mechanical and chemical polishing effects.
Implementation Method 1
colloidal silica has come to be used for finish polishing of an aluminum magnetic disk substrate as an abrasive grain component playing a role of mechanical polishing
Implementation Method 2
a chemical component playing a role of chemical polishing are mixed immediately before actual polishing
Implementation Method 3
the water-soluble polymer compound has a weight average molecular weight of 20,000 to 10,000,000 and a concentration of 0.0001 to 2.0% by mass
Data Source
AI summary
Embodiments relate to a polishing composition for a magnetic disk substrate, where the polishing composition contains colloidal silica, a water-soluble polymer compound, and water. According to at least one embodiment, the water-soluble polymer compound has a weight average molecular weight of 20,000 to 10,000,000 and a concentration of 0.0001 to 2.0% by mass.