How to use silicone-free wetting agents
1. Preparation before use
Clear application scenarios
UV curing system: Pay attention to the effect of wetting agents on curing speed and coating performance.
Water-based system: Balance wettability and foam control.
High solid coatings: Ensure the compatibility of wetting agents with resins.
Choose the right type of wetting agent
Polyethers: Suitable for water-based systems, acid and alkali resistant, but poor high temperature resistance.
Fluorocarbons: Suitable for low surface energy substrates (such as PP, PET), excellent wettability but high cost.
Polyacrylates: Strong versatility, suitable for a variety of systems, but pay attention to compatibility with resins.
Confirm the technical parameters of the wetting agent
Surface tension reduction ability: Ensure that the wetting agent can reduce the surface tension of the system to
25-32 mN/m (coating) or lower (ink).
Dynamic contact angle: Select a wetting agent that can reduce the contact angle to less than 15°.
Thermal stability: Ensure that the wetting agent does not decompose at processing temperature.
2. Usage method
Addition amount control
Initial addition amount: It is recommended to start from 0.1%-0.5% and gradually adjust according to the effect.
Upper limit control: Avoid exceeding 2.0%. Excessive amount may cause the coating to become sticky, reduce
water resistance or affect curing.
Addition time
Pre-dispersion method: Pre-mix the wetting agent with part of the solvent or water, and then add it to the main
system. It is suitable for high viscosity systems.
Post-addition method: Add it in the late grinding or paint mixing stage to avoid high temperature destroying the
molecular structure. It is suitable for UV curing systems.
Mixing process
Slow-speed stirring: Avoid high-speed stirring to produce too much foam, and control the stirring speed at 300-500
rpm.
Dispersion time: Ensure that the wetting agent is fully dispersed, and the dispersion time is generally 10-30 minutes.
3. Precautions in application
Compatibility test
Resin matching: Give priority to wetting agents that are compatible with the system resin to avoid stratification or
precipitation.
Photoinitiator effect: Test whether the wetting agent reacts with the photoinitiator (such as TPO, 1173) to cause poor curing.
Foam control
Matched with defoamer: If the system is prone to foaming, it can be matched with silicone or mineral oil defoamer, but
attention should be paid to the balance between defoamer and wetting agent.
Low shear process: Reduce high-speed dispersion and pumping to reduce the risk of foam generation.
Environmental factors
Temperature: High temperature may accelerate the volatilization of wetting agent, and the dosage needs to be increased
appropriately.
Humidity: In a high humidity environment, the amount of wetting agent needs to be increased to maintain leveling in
water-based systems.
4. Effect verification
Leveling test
Visual evaluation: Observe whether the coating surface is smooth and has no defects such as shrinkage cavities and
orange peel.
Instrument test: Use a leveling meter or a dynamic contact angle meter to quantify the leveling effect.
Performance test
Adhesion: Ensure that the wetting agent does not affect the adhesion between the coating and the substrate.
Weather resistance: Long-term exposure test to confirm that the wetting agent does not cause yellowing or powdering
of the coating.
5. Common problems and solutions
Shrinkage problem
Cause: Insufficient amount of wetting agent or mismatch with the substrate.
Solution: Increase the amount of wetting agent or replace it with a fluorocarbon wetting agent.
Excessive foam
Reason: Stirring speed is too high or defoamer is insufficient.
Solution: Reduce stirring speed and add defoamer.
Poor curing
Reason: Wetting agent reacts with photoinitiator or is added in excess.
Solution: Reduce the amount of wetting agent or replace it with a non-reactive wetting agent.
Summary
Silicone-free wetting agents significantly improve coating quality by reducing surface tension and improving leveling.
When using, it is necessary to select the appropriate type and amount of wetting agent according to the characteristics
of the system, and pay attention to compatibility, foam control and environmental factors to ensure the best effect.
