Hydrophilic Layer with Intermediate Coating for Water Repellent Resistance
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Solution Overview
Problem
Hydrophilic mirrors with a TiO2 photocatalytic layer and SiO2 hydrophilic layer suffer from rapid adhesion and accumulation of water-repellent car wash agents, leading to loss of hydrophilicity due to the low isoelectric point of SiO2, which impairs photocatalytic performance.
Innovation Solution
A hydrophilic member with a photocatalytic layer and a hydrophilic layer having an isoelectric point exceeding 7, where an intermediate layer with a low density is introduced between the photocatalytic and hydrophilic layers, formed using materials like Al2O3, to enhance water-repellent agent resistance and maintain photocatalytic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hydrophilic layer made of SiO2 is formed on the photocatalytic layer, then hydrophilicity is provided to the surface, but water-repellent car wash agents easily adhere to the surface due to low isoelectric point
Solution Approach 1:
The patent changes the isoelectric point parameter of the hydrophilic layer by selecting materials with higher isoelectric points (Al2O3: 7.4-9.2, NiO: 10.3) instead of SiO2 (isoelectric point 1-2.8). This parameter change makes the surface less attractive to cationic water-repellent agents while maintaining hydrophilicity through the high isoelectric point materials' inherent properties
Solution Approach 2:
The patent uses composite material structures where the hydrophilic layer is made of high isoelectric point materials (Al2O3 or NiO) stacked on the TiO2 photocatalytic layer. This composite structure combines the photocatalytic functionality of TiO2 with the water-repellent resistance of high isoelectric point hydrophilic materials
2Object-affected harmful factors
If a hydrophilic layer made of high isoelectric point material (Al2O3 or NiO) is formed on the photocatalytic layer, then water-repellent agent resistance is enhanced, but photocatalytic performance is significantly impaired
Solution Approach 1:
The patent employs thin film structures for both the photocatalytic layer and hydrophilic layer. By optimizing the thickness of each layer, the design allows ultraviolet light to penetrate through the hydrophilic layer to activate the photocatalytic TiO2 layer beneath, maintaining photocatalytic functionality while preserving the water-repellent resistance provided by the high isoelectric point hydrophilic layer
Solution Approach 2:
The patent applies different functional properties to different layers: the lower photocatalytic layer (TiO2) provides photocatalytic decomposition activity, while the upper hydrophilic layer (Al2O3 or NiO) provides water-repellent resistance and hydrophilicity. Each layer is optimized for its specific function, with the thin film structure allowing light transmission for photocatalysis while the top layer maintains surface properties resistant to water-repellent agent adhesion
3Ease of manufacture
If SiO2 is used as the hydrophilic layer material, then ease of manufacture is improved, but water-repellent car wash resistance is poor due to low isoelectric point
Solution Approach 1:
The patent changes the material selection parameter from SiO2 (low isoelectric point 1-2.8) to high isoelectric point materials (Al2O3 with isoelectric point 7.4-9.2 or NiO with isoelectric point 10.3). This parameter change fundamentally alters the surface chemistry to reduce electrostatic attraction between the negatively charged surface and cationic water-repellent agents, thereby improving resistance to water-repellent car wash agents
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 reduces water-repellent agent adhesion and maintains photocatalytic performance by using a high isoelectric point hydrophilic layer and a low-density intermediate layer, ensuring the hydrophilic surface remains effective against organic dirt and water-repellent agents.
Implementation Method 1
enables the hydrophilicity of the hydrophilic layer to be recovered by decomposition and removal of the adhering organic dirt by means of a photocatalytic action of the underlying photocatalytic layer
Implementation Method 2
a layer that causes the hydrophilic layer to be formed so as to have a low density compared to a case where the hydrophilic layer is formed directly on the photocatalytic layer under the same film forming condition
Data Source
AI summary
A hydrophilic member that enables provision of favorable photocatalytic performance while enhancing water repellent agent resistance and a method for manufacturing the same are provided. A maintenance method for removing a water repellent agent adhering to a surface of a hydrophilic layer of a hydrophilic member, the water repellent agent having a cation property, is provided. A photocatalytic layer is formed on a base material. An intermediate layer is formed on the photocatalytic layer. A hydrophilic layer having an isoelectric point exceeding 7 is formed on the intermediate layer. The intermediate layer is a layer that causes the hydrophilic layer to be formed so as to have a low density compared to a case where the hydrophilic layer is formed directly on the photocatalytic layer under the same film forming condition. A water repellent agent adhering to a surface of the hydrophilic layer can effectively be removed using sodium bicarbonate.