Mar-Reducing Overcoat for Sputtered Low-E Coatings
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Solution Overview
Problem
Sputter-deposited low-E coatings are prone to damage due to surface roughness and weak bonds, leading to potential marring during handling, which increases costs and reduces yield despite special handling precautions.
Innovation Solution
Applying a 'slippery' organic overcoat via an evacuative process to modify surface energy, reducing friction and enhancing mar resistance, which can be done through various methods such as using a water-soluble material, plasma enhanced chemical vapor deposition, or feeding a vapor phase material into the coater's vent gas stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sputter-coated layer stack is applied to create low-E or solar coatings, then the coating provides desired optical properties, but the coating becomes soft and prone to scratching and marring
Solution Approach 1:
The patent applies a two-layer composite structure: a sputter-coated layer stack providing optical properties (low-E or solar coating) and an organic overcoat providing mechanical protection. This composite structure combines the advantages of both materials - the inorganic layer for optical performance and the organic layer for scratch resistance and surface hardness.
Solution Approach 2:
The patent modifies surface energy parameters by applying an organic overcoat that changes the surface friction and contact angle characteristics. This parameter change transforms the surface from high-friction and hydrophilic to low-friction and hydrophobic, reducing the propensity for scratch marring while maintaining optical properties.
2Reliability
If special handling precautions are taken to protect soft coatings from damage, then the potential for marring is reduced, but the costs and time required for manufacturing increase
Solution Approach 1:
The patent applies a protective organic overcoat during the coating process itself, before the article leaves the manufacturing line. This preliminary protective action eliminates the need for subsequent special handling precautions during transportation and installation, thereby improving productivity while maintaining coating durability.
Solution Approach 2:
The organic overcoat provides self-protecting properties to the coating system, making it inherently more resistant to marring without requiring external protective measures. The overcoat's low surface friction and hydrophobic characteristics enable the coating to resist damage autonomously during normal handling and use.
3Reliability
If an overcoat is applied to reduce surface friction and enhance mar resistance, then the contact angle increases and scratching is reduced, but the process complexity increases
Solution Approach 1:
The patent combines the coating and overcoat application processes into a single integrated operation. The organic overcoat is applied in the same coating line where the inorganic layer stack is deposited, merging two processes into one coordinated operation that reduces overall process complexity despite adding functional layers.
Solution Approach 2:
The organic overcoat acts as an intermediary layer between the inorganic layer stack and the external environment. This intermediary provides the protective functions (scratch resistance, low friction, hydrophobicity) while allowing the underlying optical coating to maintain its performance, effectively mediating between the delicate inorganic layers and harsh external conditions.
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 overcoated articles exhibit increased contact angles and reduced surface friction, making them less susceptible to scratching, with damage only visible microscopically, and maintaining durability without observable color shifts or significant thickness changes.
Implementation Method 1
The overcoat may be applied via an evacuative process
Implementation Method 2
vapor in the heatable chamber may be built up
Data Source
AI summary
Certain example embodiments of this invention relate to techniques for applying an overcoat (e.g., which may include an organic material) to a coated article having a layer stack already disposed thereon in order to reduce the potential for surface marring. An evacuative process may be used to deposit the mar reducing overcoat. The coated article including the mar-reducing overcoat has a contact angle greater than, and a surface friction less than, a contact angle and a surface friction of the single- or multi-layer stack supported by the substrate alone. Any marring due to cat-scratching or the like preferably would not be visible at 4× magnification following application of the mar reducing overcoat.