Optimizing Creasing Tool Geometry for Barrier Coated Boxboard Converting
Optimizing creasing geometry for barrier board requires expanding female channel width and applying polished male rule radii to prevent barrier film splitting.
Poly-Extrusion Barrier
Moisture Protection
Protection of food products through the application of a polymer coating prevents the transmission of water vapor and grease through the paperboard. A poly-extrusion barrier is created by melting a synthetic resin and extruding it as a thin film onto a moving web of paper. This process provides a functional layer that is both liquid tight and heat sealable.
Thermal Application
The molten polymer is forced through a flat die and pressed onto the substrate using a series of chilled rollers. Adhesion between the plastic and the paper is achieved through a combination of heat and pressure. Common materials used for this purpose include polyethylene or polypropylene depending on the required temperature resistance.
The thickness of the layer is measured in grams per square meter and can be adjusted to suit the specific barrier needs. This method allows for the creation of a composite material that combines the strength of paper with the protective properties of plastic. Regular testing of the bond strength ensures that the layers do not delaminate during use.
Functional Limit
The barrier is effective against liquids but can be compromised by pinholes or damage to the coating. Recycling of these materials requires specialized equipment to separate the plastic from the wood fibers. This coating defines the standard for liquid packaging and frozen food containers.
It ensures that the contents remain fresh and protected from external contamination.