Material Composition
Stable chemical systems hold solid polymer particles within a water phase for application to paper surfaces. Specialized aqueous dispersions provide a plastic-free alternative to traditional extrusion coatings by utilizing synthetic or natural polymers that remain suspended until drying. The formulation prevents the particles from clumping together during storage.
Barrier Mechanism
Heat and air removal during the drying stage force the suspended particles to fuse into a continuous protective layer. Because aqueous dispersions rely on water evaporation rather than molten plastic application, the resulting film is typically thinner and more compatible with standard recycling streams. This layer blocks water vapor and grease effectively.
Application Performance
Coating stations on a paper machine or off-line converter apply the fluid using rod, blade, or air-knife methods to ensure an even finish. Achieving the correct viscosity is essential for maintaining a consistent coat weight across the width of the web. If the solids content is too low, the substrate may absorb excessive water and lose dimensional stability.
If the solids content is too high, the coating may streak or fail to form a smooth surface. These systems demand precise temperature control during the curing process to prevent the film from becoming brittle. Proper curing also ensures the coating does not stick to itself when the paper is wound into reels.
This method represents a major shift toward circular packaging designs.
