PP EVA EVOH EVA PP Multi-Layer Sheet Co-Extrusion Line: The Machine That Stacks Five Polymers Into One Sheet

A PP EVA EVOH EVA PP multi-layer sheet co-extrusion line produces the barrier sheet used for the food packaging, the medical pouch, and the chemical container. The five layers are not decoration. Each one does a job. The PP outer layers give the stiffness and the heat resistance. The EVA tie layers bond the EVOH to the PP. The EVOH core blocks the oxygen and the aroma. The sheet comes out of the die as one piece, with the layers bonded but not mixed. For the packaging converter, the line is the equipment that builds the barrier into the sheet itself.

The Five Extruders and the Feedblock

The line runs five extruders, one for each layer. The PP extruders feed the outer skins. The EVA extruders feed the tie layers. The EVOH extruder feeds the barrier core. The five melt streams converge in the feedblock. The feedblock arranges the layers in the order and keeps them distinct.

A PP EVA EVOH EVA PP multi-layer sheet co-extrusion line with the properly designed feedblock holds the layer ratios across the width. The EVOH core stays continuous. The tie layers stay bonded. The sheet that loses the EVOH continuity loses the barrier.

The Die and the Layer Integrity

The combined melt enters the flat die as the stratified flow. The die spreads the sheet to the width without the layer mixing. The die manifold has to avoid the dead spots where one polymer stagnates and degrades. A PP EVA EVOH EVA PP multi-layer sheet co-extrusion line with the streamlined manifold produces the sheet with the clean interfaces.

The EVOH and the Moisture

The EVOH is the barrier, but it is the moisture-sensitive. The EVOH absorbs the water and loses the barrier property when it is wet. That is why the EVOH sits in the core, between the two PP skins, and the tie layers. The PP keeps the moisture away from the EVOH. The line that keeps the layer structure intact keeps the barrier working.

The Cooling and the Thickness

The sheet exits the die and enters the three-roll stack. The rolls cool the sheet and set the thickness and the surface. The line with the proper roll temperature and the gap control produces the sheet with the uniform thickness.

Here is what a PP EVA EVOH EVA PP multi-layer sheet co-extrusion line has to deliver:

• Five extruders with the independent temperature control
• Feedblock that holds the layer order and the ratio
• Flat die with the streamlined manifold
• Three-roll stack with the thickness control
• Layer thickness measurement and the feedback
• Winding with the tension control

The Wood-Plastic Connection

The same co-extrusion discipline runs the PE/PP Wood-Plastic Composite Extrusion Line. The WPC line combines the polymer with the wood fiber and forms the decking, the fencing, and the profile. The layer control and the die design matter in the same way. The producer who runs both lines controls the packaging sheet and the composite profile from the same technical base.

Where the Five-Layer Sheet Goes

The food packaging uses the sheet for the barrier tray and the lidding. The medical packaging uses the sheet for the sterile pouch. The chemical packaging uses the sheet for the solvent-resistant container. The EVOH core blocks the oxygen and the aroma and extends the shelf life.

The Layer That Breaks and the Barrier That Fails

The EVOH layer breaks because the flow was unstable or the temperature was wrong. The barrier fails. The tie layer delaminates because the EVA was not compatible with the adjacent polymer. The right grade holds. The sheet curls because the cooling was uneven. The balanced cooling holds the flat.

A PP EVA EVOH EVA PP multi-layer sheet co-extrusion line stacks five polymers into one sheet. The feedblock arranges. The die spreads. The rolls cool. Choose a line with the right extruders, the right feedblock, and the right thickness control.