Multi-Layer Coating Board Production: Optimizing Forming and Coating for Premium Packaging
Coating board production combines multi-layer forming technology with precision coating application to achieve the surface quality required for high-end packaging. The integration of stock preparation, multi-ply forming, and coating systems requires careful equipment selection and process parameter control to ensure consistent product quality and efficient operation.
Multi-Layer Forming Technology
Modern coating board machines typically employ three to five ply forming configurations:
- Top ply: Bleached kraft or high-brightness recycled fiber at 30-50 g/m2 basis weight, forming the printable surface
- Under-top ply: Mechanical or recycled fiber at 20-30 g/m2, providing bulk and stiffness
- Middle plies: Recycled fiber or CTMP at 60-120 g/m2 each, the primary structural layers
- Back ply: Recycled or unbleached fiber at 30-40 g/m2
Each ply requires independent stock preparation including dedicated screening and refining systems. Headbox consistency for top plies is typically 0.5-0.8%, while middle and back plies operate at 0.8-1.2%.
Coating Application Technology
Coating board requires precise coating application to achieve the required surface properties. Key coating equipment includes:
- Blade coater: Applies 8-15 g/m2 coating layer per side at speeds up to 800 m/min. Provides excellent surface smoothness and coverage
- Film press / metering size press: Pre-coating application of 3-6 g/m2 starch or pigment, improving surface strength for subsequent coating layers
- Air knife coater: For specialty coating applications requiring contour coating of 5-20 g/m2
Coating color formulation with 60-68% solids content using calcium carbonate and clay pigments with synthetic binders ensures optimal coverage and printability.
Quality Parameters and Process Control
Key quality metrics for coating board production:
- Surface smoothness: Parker Print Surf (PPS) roughness below 1.5 um at 1000 kPa
- Brightness: 80-88% ISO for top ply (bleached), 70-78% for back ply
- Gloss: 45-65% at 75-degree measurement angle
- IGT surface strength: above 1.5 m/s with medium-tack ink
Online measurement systems for basis weight, moisture, caliper, and coating weight enable real-time process adjustments.
For packaging producers seeking to upgrade coating board production capability, properly specified multi-layer forming and coating equipment delivers measurable competitive advantages in print quality and production efficiency.
Contact Leizhan Technology for complete coating board production line solutions.
Email: leizhanzhang@gmail.com