Hydrophobic Coated Substrates for Foldable Displays
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Solution Overview
Problem
Foldable substrates used in display applications, such as LCDs and OLEDs, face durability issues due to abrasion and loss of functionality, particularly with organic coatings that lack sufficient abrasion resistance.
Innovation Solution
The development of coated articles with a hydrophobic coating that exhibits good adhesion and abrasion resistance, achieved through a polishing method using a slightly alkaline solution and a loose abrasive like silica, zirconia, or alumina, which reduces material removal by etching and enhances surface roughness for improved adhesion and durability, along with a washing process that utilizes a fluorinated solvent to prevent moisture absorption and facilitate subsequent coating adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic coating is applied to provide antibacterial and easy-to-clean functionality, then hydrophilic character is improved, but abrasion resistance deteriorates
Solution Approach 1:
The patent changes the surface energy parameters of the substrate by applying a hydrophobic coating with specific contact angle characteristics (100° or more), transforming the surface from hydrophilic to hydrophobic while maintaining durability through the coating's inherent abrasion resistance
Solution Approach 2:
The patent creates a composite structure combining the substrate with a hydrophobic coating layer, where the coating provides both the desired hydrophobic functionality and enhanced abrasion resistance, solving the contradiction between functional performance and mechanical durability
2Manufacturing precision
If polishing is performed to improve surface roughness for better coating adhesion, then adhesion is improved, but etching may introduce irregularities that reduce mechanical strength
Solution Approach 1:
The patent optimizes the polishing parameters including using slightly alkaline solutions (pH 7-11) and controlling the rotation rate (95-145 rpm) and pressure (25-27.5 kPa) to achieve the desired surface roughness (Ra ≤ 1.6 nm) while minimizing etching that would compromise mechanical strength
Solution Approach 2:
The patent replaces purely mechanical polishing with a combined chemical-mechanical polishing process using slightly alkaline solutions, which reduces material removal by etching rather than friction, thereby achieving smooth surfaces without introducing strength-reducing irregularities
3Productivity
If high rotation rate and pressure are applied during polishing to increase material removal by abrasion, then polishing efficiency is improved, but thermal control and quality may deteriorate
Solution Approach 1:
The patent optimizes the polishing parameters to a specific range: rotation rate of 95-145 rpm and pressure of 25-27.5 kPa, which balances polishing efficiency with thermal and quality control, preventing excessive heat generation and maintaining surface integrity
Solution Approach 2:
The polishing process uses periodic application of polishing liquid at controlled rates (1-10 mL/min) to continuously cool the surface and remove debris, maintaining thermal control while achieving efficient material removal through repeated abrasion cycles
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 method results in coated articles with a water contact angle of 100° or more after 8,000 cycles in a Steel Wool Abrasion Test, maintaining hydrophobicity and oleophilicity, and enhances puncture and impact resistance by improving the substrate's surface roughness and chemical strengthening, ensuring long-term durability and performance.
Implementation Method 1
methods provided herein increase a fraction of material removed by friction (e.g., abrasion, as opposed to etching)
Implementation Method 2
Providing a slightly alkaline solution (e.g., pH from 7 to 11 or from 9 to 10.5) can reduce an amount of a material removed by etching as opposed to abrasion during the polishing
Implementation Method 3
any fluorine-containing residue remaining after the washing can reduce an amount of moisture that is transferred to and/or absorbed by the first major surface
Data Source
AI summary
Methods of polishing and/or forming a coated article include polishing a first major surface of a substrate with a polishing liquid. Then, methods include washing the first major surface with a cleaning liquid. In aspects, the cleaning liquid has a pH from about 7 to about 11. In aspects, the polishing liquid is supplied at a rate of 20 mL/min or less. In aspects, methods can further include applying a hydrophobic coating to form a coating with an exterior surface of the coated article. A coated article includes a hydrophobic coating with an exterior surface disposed on a first major surface of a substrate. A water contact angle of the exterior surface is about 100° or more. The coated article can exhibit an abraded water contact angle of about 100° or more after being abraded with steel wool for 8000 cycles in the Taber Test.