Excimer and EB: A New Dimension in Gloss Control

Challenges and Current Status of Matte Effects

High-gloss surfaces reflect light smoothly, creating a lustrous appearance, while matte effects rely on surface roughness to scatter light. Traditional methods use matting agents (e.g., particles, waxes) to disrupt coating surfaces. However, challenges arise in EB (electron beam) and UV-curing systems:

Dispersion Issues: Matting agents tend to settle, requiring constant agitation and struggle to release uniformly.

Performance Trade-offs: Agents may reduce water resistance or cause contamination.

Process Complexity: Matte coatings are difficult to clean, impacting production efficiency.

Excimer Technology: A Disruptive Alternative

Excimer lamps generate 172nm vacuum ultraviolet (VUV) light via radiofrequency excitation, penetrating only a few nanometers into the coating surface. This triggers thin-layer polymerization (Figure 1). Polymerization shrinkage stress creates micro-wrinkles, directly forming a matte texture. Subsequent UV or EB curing completes the process—no matting agents needed, enabling "one-click" gloss-to-matte switching.

Key Advantages:

Simplified Formulation: Eliminates matting agent dispersion and stability issues.

Enhanced Performance: Tests show excimer-treated coatings exhibit 2× higher MEK resistance and 3× improved scratch resistance.

Process Compatibility: Shares nitrogen inertization systems with EB, reducing costs. 

Synergistic Applications of Excimer and EB

No Photoinitiator Required: 172nm photons (7.2eV energy) directly break C-C and C-H bonds, bypassing photoinitiators—ideal for sensitive applications.

Precision Gloss Control: In decorative paper industries, excimer+EB systems reduce 60° gloss values from ~90 units to 10–20 units (Figure 2).

Limitations: Gloss adjustment is "all-or-nothing," lacking gradient flexibility.

Technical Challenges and Innovations

Pre-gel Dilemma: Traditional UV pre-gel requires photoinitiators, but low-dose EB (2–5 kGy) enables initiator-free pre-gel (Figure 3), albeit at higher costs.

Formulation Compatibility: Not all resins respond to excimer; reactive monomers/oligomers must be screened.

Expanded Applications: In packaging, excimer enables "matte accents"—EB-cured glossy base + excimer-treated transparent ink creates intricate matte patterns (Figure 4).

Future Potential and Industry Impact

Excimer technology offers eco-friendly, high-efficiency matte solutions for:

Luxury Packaging: Scratch-resistant, low-gloss exteriors for premium products.

Electronic Coatings: Functional surfaces with matte aesthetics.

Innovative Printing: High-contrast gloss-matte designs.

Conclusion

The excimer-EB synergy overcomes traditional matting limitations, opening new avenues for gloss control. Despite challenges in adjustability and cost, its performance and process advantages position it as a key tool for industrial coating upgrades. With further refinement, excimer could replace conventional matting methods, driving EB/UV curing toward high-value applications.

Key Innovations at a Glance

Outlook
Future advancements require optimizing wavelength compatibility, cost efficiency, and compatibility with water-based coatings and flexible substrates. Industry-academia collaboration will accelerate excimer’s transition from "lab marvel" to "industrial staple," unlocking innovation in surface treatment.

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