Anti-fouling coatings resist fingerprints and smudges on smartphones and car displays. The industry relies on fluorine-based materials (like fluoropolymers and silane coupling agents) because they powerfully repel both water and oil. However, because the liquid itself is designed to repel, making it stick evenly to a glass surface is extremely difficult. Here is how surface modification (pre-treatment) and ultra-slow withdrawal speeds prevent uneven fluorine coatings.
1. Why Fluorine Liquids Cause Uneven Coatings
Low Surface Tension Causes Pooling and Interference Fringes
Fluorine liquids have very low surface tension, meaning they want to repel almost everything. If you pull the glass out of the tank too fast, the liquid fails to stick evenly, forming thick beads and streaks.
Anti-fouling films are incredibly thin—usually just a few nanometers. If the thickness is uneven, light interference creates a rainbow-colored stain (interference fringes) or a cloudy haze, ruining the display’s visibility.
2. “Super-Hydrophilic” Prep for Repellent Liquids
Strong Chemical Bonds via Vacuum Plasma
To make slippery fluorine stick to the glass, surface preparation is everything. Basic washing is not enough. You must use UV-ozone or vacuum plasma treatments to make the glass surface “super-hydrophilic.” This allows the OH groups (hydroxyl groups) on the glass to chemically bond tightly with the fluorine, creating a highly durable, scratch-resistant layer.
3. [Solution] Maintaining Extremely Slow Withdrawal Speeds
Total Support from Pre-Treatment to Coating
Once the glass is perfectly prepped, you must leave the thinnest possible layer of liquid on it. Because fluorine liquids run off so easily, you must pull the glass out at an extremely slow speed (from mm/min down to nm/sec) with zero vibration.
SDI dip coaters are built specifically for this type of ultra-slow, vibration-free movement required for ultra-thin films. Additionally, our Contract Coating service handles the entire process in-house—from the critical vacuum plasma pre-treatment to the final dip coating and thermal curing.
▼ From Plasma Prep to Drying: Learn more about our Contract Coating Service https://www.sdicompany.com/en/jutaku/