How to Avoid "Orange Peel"?
In summary, the core causes of the orange peel problem in release film coating are as follows:
- Excessively large surface tension gradient of the coating solution (mainly caused by overly rapid solvent volatilization).
- Insufficient fluidity of the coating solution itself (high viscosity and insufficient leveling agent).
- Inadequate leveling time between coating and the onset of surface curing (high coating speed and premature initiation of drying).
The approaches to solving the orange peel problem are generally as follows:
- Optimize the solvent system: Increase the proportion of high-boiling-point, slow-drying solvents to slow down the surface volatilization rate.
- Adjust viscosity: Appropriately reduce the viscosity of the coating solution on the premise of meeting process requirements.
- Add suitable leveling agents: Select leveling agents with good compatibility that can effectively reduce the dynamic surface tension gradient, and ensure a sufficient dosage.
- Optimize the drying process: Lower the inlet temperature of the oven and adopt gradient temperature rise; appropriately reduce wind speed and ensure uniform air distribution; guarantee adequate drying time.
- Optimize coating parameters: Properly decrease the coating speed; ensure accurate setting of coating gaps and uniform coating thickness; inspect the status of the coating head (e.g., whether the die lip is clean and flat, and whether the scraper is worn).
- Inspect the substrate: Ensure that the substrate surface is clean, with appropriate surface tension (conduct corona treatment if necessary to improve surface energy) and flatness.
- Control the environment: Maintain a suitable temperature and humidity environment.
It is necessary to identify the root cause and implement effective solutions through systematic troubleshooting and experiments, based on the specific production line conditions, coating solution formulation and substrate type.
Topwin is one of the leading professional manufacturers and solution providers with more than 20 years of experience, and has domestic top-level engineers in the silicone surfactant industry. Specializing in research and development, production, sales, and marketing of silicone-based special functional performance materials, Topwin also serves as a professional provider of technical services. Now our products are widely used in Polyurethane Foam, Corp Protection, Coatings and Inks, Leather & Textile, Silicone Release Coating for Paper and Film, Personal Care, and others.
