What to do if the adhesion of UV ink is not enough？
Date: Jul 02 2024 From: Star Color
The insufficient adhesion of UV inks is actually not a common phenomenon, given the remarkable advancements UV ink technology has made over the years. Even on non-absorbent materials, UV inks exhibit exceptional adhesion after proper corona treatment. However, when UV ink adhesion becomes insufficient, it's essential to troubleshoot the issue from multiple angles. Below are some common causes to consider:
Printing Material Issues:
- The substrate surface is too smooth and lacks active groups, preventing ink adhesion.
- Residual UV primer on the substrate surface has not dried completely, affecting ink adhesion.
Ink Issues:
- The curing agent added to the UV ink has not been thoroughly mixed, leading to uneven shrinkage during curing.
- Residual UV primer in the ink fails to react chemically with the substrate surface, resulting in poor adhesion.
Printing Process Issues:
- Insufficient UV lamp power or curing time, resulting in incomplete ink curing.
- Excessively fast printing speed or insufficient printing pressure, affecting ink adhesion.
Other Factors:
- Excessive use of ethanol diluent, reducing the degree of photopolymerization.
- Insufficient corona treatment of the film surface, leading to inadequate surface tension.
- Improper ink storage, affecting its stability.
Solutions Tailored to Each Cause:
For Printing Materials:
- Roughen the substrate surface to increase roughness and active groups.
- Use activators to enhance the substrate's surface activity and improve ink adhesion.
- Ensure complete drying of the UV primer on the substrate before printing.
For Ink Issues:
- Thoroughly mix the curing agent into the UV ink using a high-speed mixer to ensure uniformity.
- Choose UV ink brands and models compatible with the substrate to ensure adhesion.
For Printing Process:
- Increase UV lamp power and curing time to ensure complete ink curing.
- Reduce printing speed and increase printing pressure to improve ink adhesion.
- Maintain stable printing speed and pressure to avoid fluctuations affecting adhesion.
- Regularly check and replace aged UV lamp tubes to ensure UV light transmittance.
- Adjust light source power as needed to meet curing requirements.
- Use high-quality UV LED curing machines or UV mercury lamps to improve curing efficiency and stability.
For Other Factors:
- Avoid using ethanol to dilute UV ink; instead, use UV ink-specific diluents if viscosity reduction is necessary.
- Ensure adequate corona treatment of the film surface to meet surface tension requirements.
- Store UV ink properly, avoiding direct sunlight and high temperatures to maintain its stability.
Using Adhesion Promoters:
- Adding an appropriate amount of adhesion promoter to the ink can enhance physical adsorption between the ink and substrate, thereby improving adhesion.
Introducing Post-Curing Processes:
- For special materials or products with high requirements, consider adding a post-curing process to further enhance adhesion through heating or additional UV exposure.
By implementing these measures, the issue of poor UV ink adhesion can generally be effectively resolved, enhancing the print quality and stability of products. For more information on UV ink-related issues, please visit our website at www.starcolor-ink.com
RU
EN
CN
