Extrusion Coating Lamination Compound Machine

Extrusion Coating Lamination Compound Machine

An extrusion coating lamination compound machine combines a layer of plastic film with a flexible substrate such as paper or non-woven fabric.extrusion coating lamination compound machine The resulting product is a functional, high-performance film or sheet that provides a barrier to oxygen and moisture and enhances the strength and stiffness of the substrate. It is commonly used in food packaging and many other applications in the flexible packaging industry.

The process uses an extruder to force melted thermoplastic resin through a horizontal slot-die onto a moving web of the substrate. A combination of heat, pressure and time enables the melt to adhere to the substrate and coagulate to form a permanently coated web structure. The substrate may be paper, corrugated board, or metal foil.

During the extrusion coating process, the melt is typically applied to the substrate in a thin coat or layer. The thickness of the coating varies according to the application. In the case of laminated fabrics, a thicker coating is needed to provide the required mechanical properties.

In the case of paper, a thinner coating is normally used to protect the printed surface from moisture. In both cases, the coating is heated to a temperature above its softening point to ensure that it fuses with the substrate. This allows the converting process to take place without the use of chemical solvents that would otherwise contaminate the finished products with toxic substances.

The hot-melt adhesives that are most often used in converting processes can be deposited either by slot die extrusion or by roller and calender adhesion techniques. The adhesives are melted by heat and spread on the fabric while still in a hot state, which allows the bond to occur on re-solidification as the coating cools.

There are a number of challenges that can be encountered when using extrusion coating in combination with a blown sealant. For example, the thermal migration of the blown sealant through the extrusion-coated structure can create organoleptic issues in high-end tea and coffee packaging structures. This can be solved by running the extrudate and sealant on the first head of a three-lam structure or by replacing the blown sealant with a more thermally stable polymer, such as a higher molecular weight LDPE or m-VLDPE.

Another challenge can be caused by crazing, which is a form of curling in which one side of the film cools more quickly than the other. Crazing can be minimized by adjusting the extruder carriage position to move the extrudate closer to the thermally stable substrate side, and by using a metalized chill roll on the auxiliary substrate to reduce friction with the coated extrudate and prevent contact heat. A lower melt temperature can also help to reduce the occurrence of crazing, but should not be so low that it compromises the bond integrity of the film. In addition, it is important to consider the possibility of oxidation in the melt curtain, which can result in reduced molecular intermingling and decreased seal strength.

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