Stacked Anti-Fogging Coating for Transparent Members
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Solution Overview
Problem
Existing methods for preventing fogging on transparent substrates, such as using heaters or improving surface wettability, face challenges like increased weight, power consumption, and reduced transparency due to swelling or light scattering when trying to enhance anti-fogging properties.
Innovation Solution
A transparent member is created with a stacked structure of an organic layer and an inorganic porous layer on a substrate, where the organic layer includes an organic molecular chain network with acidic groups and the inorganic porous layer is hydrophilic, allowing for continuous retention of a water film and prevention of fogging without distorting images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heater is provided on the substrate to maintain the substrate surface at a dew-point temperature or higher, then anti-fogging properties are maintained semipermanently, but weight and space increase due to the heater and power source
Solution Approach 1:
The patent replaces the mechanical heating system (heater and power source) with a chemical/physical coating system. The organic layer containing hygroscopic substances and the inorganic porous layer work together to prevent fogging through moisture absorption and water film formation, eliminating the need for active heating components and thereby reducing weight.
Solution Approach 2:
The coating system operates autonomously without external power sources. The organic layer automatically absorbs moisture from the environment, and the inorganic porous layer passively maintains a water film on the substrate surface through capillary action and hydrophilicity, providing continuous anti-fogging protection without requiring active control or energy input.
2Reliability
If the film thickness is increased or moisture absorption amount per unit volume is excessively increased to improve anti-fogging properties, then water droplet development is suppressed, but transparency is reduced or face distortion occurs due to swelling
Solution Approach 1:
The patent divides the anti-fogging function into two separate layers: the organic layer responsible for moisture absorption and the inorganic porous layer responsible for water film formation and transparency maintenance. This segmentation allows each layer to be optimized for its specific function, preventing the transparency issues that would result from using a single thick layer.
Solution Approach 2:
Each layer is designed with specific local properties: the organic layer contains hygroscopic substances for moisture absorption, while the inorganic porous layer has hydrophilic properties and controlled porosity for water film formation. This local quality differentiation ensures that moisture management and optical clarity are achieved in their respective zones without interfering with each other.
3Reliability
If uneven structure or water absorbing polymer is used to improve water wettability, then anti-fogging properties are improved, but water droplets can only be prevented from developing before the film is saturated with water
Solution Approach 1:
The patent uses a composite structure combining an organic layer (with hygroscopic polymers) and an inorganic porous layer (with metal oxide particles). This composite material system provides sustained anti-fogging action because the organic layer continuously supplies moisture to the inorganic layer, which maintains the water film on the substrate surface, extending the duration of effectiveness beyond what either material could achieve alone.
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 provides excellent transparency and long-lasting anti-fogging properties, suitable for various applications including windows, lenses, and optical systems, by effectively managing water absorption and retention without compromising image quality or structural integrity.
Implementation Method 1
the inorganic porous layer has hydrophilicity
Implementation Method 2
a hygroscopic film is provided on the surface of a substrate, and the film is allowed to absorb water to prevent water droplets from developing
Data Source
AI summary
Provided are a transparent member having excellent transparency and maintaining anti-fogging properties for a long period of time and a method for producing a transparent member. A transparent member includes a substrate and a stacked body having an organic layer and an inorganic porous layer stacked on the substrate in the mentioned order such that the both layers are in contact with each other, in which the organic layer includes an organic molecular chain network including an organic polymer chain and an organic crosslinking chain having 3 or more to 30 or less carbon atoms, and an acidic group aggregate, and in which the inorganic porous layer has hydrophilicity and includes silicon oxide.