Extrusion coating process

Extrusion coating and extrusion laminating are converting processes that allow different substrate materials to be combined to obtain a single compound structure. The materials involved may include plastics, paper, carton board, or aluminum foils.

Extrusion coating and laminating lines are usually custom-built and can be configured for a variety of applications including liquid packaging, aseptic drink containers, flexible packaging, toothpaste tubes, medical packaging, industrial wraps, insulation backed materials, and plastic coated tablecloths, as well as sacks for products as diverse as cement, cereal grain, and dry chemicals.

Extrusion coater laminators deliver a combined substrate, the component elements of which would be very difficult to separate. The combined substrate inherits highly enhanced physical properties and barrier protection performance from its component elements.

In the extrusion coating process an extruder forces melted thermoplastic resin through a horizontal slot-die onto a moving web of substrate. The resulting product is a permanently coated web structure. Extrusion lamination is a similar process to extrusion coating, where the resin is extruded between two substrates and acts as a bonding agent.

Inside an extrusion coating and laminating line the substrates and melt are nipped at a bonding station. This consists of a large roll, a pressure roll, and a counter-pressure roll cooled by water. The combination of the pressure between the rolls and the temperature permits delivery of the correct adhesion level.

The final product is rewound as a permanently bonded multi-ply laminated structure. Most plastic films and foils require a primer coating before they are used in the extrusion process.

BOBST extrusion coating machines are fully integrated turnkey lines which can process a wide range of different materials from film and aluminum foils, to heavyweight papers and board.