External Low-E Coatings for Durable Glass Anticondensation
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Solution Overview
Problem
Existing anticondensation coatings for glass surfaces, such as skylights, are prone to scratching, color change, and are inefficient, while active heating solutions are time-consuming and energy-intensive.
Innovation Solution
A multilayer thin-film anticondensation coating comprising silicon nitride, transparent conductive oxide (TCO), and zirconium oxide layers with low hemispherical emissivity and sheet resistance, applied to the exterior surface of glass substrates, which retains heat and prevents condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin-film anticondensation coating is applied to the exterior surface of a window, then condensation prevention is improved, but the coating scratches easily and changes color over time
Solution Approach 1:
The patent applies a composite coating structure consisting of multiple layers: a base coat layer containing fluorinated silica sol and silica particles, an intermediate coat layer with fluorinated silica sol and fluororesin particles, and a clear coat layer with fluorinated silica sol and fluorocarbon particles. This multi-layer composite structure provides both condensation prevention and enhanced durability by distributing functional requirements across different material layers.
Solution Approach 2:
The patent applies different materials and properties to different layers of the coating. The base coat provides adhesion and initial condensation resistance, the intermediate coat enhances fluorine content for hydrophilicity, and the clear coat provides hardness and scratch resistance. Each layer has optimized local composition to address specific requirements.
2Reliability
If active heating elements are used to reduce condensation buildup, then condensation prevention is improved, but energy consumption increases and response time is delayed
Solution Approach 1:
The patent creates a passive coating system that automatically prevents condensation through its inherent hydrophilic properties. The fluorinated silica sol and fluororesin particles create a surface that actively attracts and spreads moisture, preventing droplet formation without requiring external energy input or active control systems.
Solution Approach 2:
The patent replaces active mechanical heating systems with a passive chemical surface treatment. Instead of using electrical heating elements to warm the glass surface, the coating chemically modifies the surface properties to prevent condensation through hydrophilic attraction, eliminating the need for energy-consuming heating mechanisms.
3Reliability
If a single-layer FTO coating is applied, then condensation prevention is achieved, but the coating lacks sufficient hardness and scratch resistance
Solution Approach 1:
The patent replaces the single-layer FTO coating with a multi-layer composite coating using fluorinated silica sol combined with various particles (silica, fluororesin, fluorocarbon). This composite structure achieves both condensation prevention and enhanced scratch resistance by combining the hydrophilic properties of fluorinated silica sol with the hardness of particle reinforcements.
Solution Approach 2:
The patent changes the material composition parameters by introducing fluorinated silica sol as the base material and adding different types of particles in specific layers. The fluorine content and particle distribution are optimized to achieve the desired balance between condensation resistance and mechanical durability.
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 coating effectively reduces condensation on glass surfaces by maintaining heat retention and durability, meeting energy efficiency standards and aesthetic requirements.
Implementation Method 1
a layer comprising a transparent conductive oxide (TCO), wherein the TCO is of or including Indium Tin Oxide (ITO)
Implementation Method 2
the anticondensation coating has a hemispherical emissivity of less than less than 0.23
Implementation Method 3
pyrolitically depositing a 4000-6000 angstrom thick fluorine-doped tin oxide (FTO) coating
Data Source
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AI summary
Certain example embodiments of this invention relate to articles including anticondensation and/or low-E coatings that are exposed to an external environment, and/or methods of making the same. In certain example embodiments, the anticondensation and/or low-E coatings may be survivable in an outside environment. The coatings also may have a sufficiently low sheet resistance and hemispherical emissivity such that the glass surface is more likely to retain heat from the interior area, thereby reducing (and sometimes completely eliminating) the presence condensation thereon. The articles of certain example embodiments may be, for example, skylights, vehicle windows or windshields, IG units, VIG units, refrigerator/freezer doors, and/or the like.