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US 4,180,427 AGranted
Foamed thermoplastic material laminated with a sheet-like covering material
AssigneePrimex Plastics Corporation
InventorPaul J. Bertsch
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AssigneePrimex Plastics Corporation
InventorPaul J. Bertsch
Estimating the term…
A layer of foamed thermoplastic material, such as polystyrene foam, is coated on at least one of its surfaces with a sheet of covering material. The covering material can be kraft paper, metal foil, a fabric or similar sheet-like material. To assure adequate adherence of the covering material to the foamed material, a corona discharge is directed against the surface of the foamed material to burn away any impurities and destroy the residual monomer film. The covering material is heated to a temperature above the melting point of the foamed material and then applied to the treated surface in a way that the foam cells are not damaged. During the laminating operation, heat from the covering material aids the bonding of the foamed material to the covering material. Further, the heat transmitted to the foamed material causes it to expand and reduce in density.
A process for laminating a sheet of covering material onto a surface of a layer of foamed thermoplastic material comprising the steps of cooling and aging for at least 24 hours the layer of foamed thermoplastic material, moving the layer of cooled and aged foamed thermoplastic material along a path of travel, bombarding the surface to receive the sheet of covering material as it moves along the path of travel with a continuous plasma of ionized particles for burning away impurities on the surface and breaking up the film of residual monomer thereon, heating the sheet of covering material to a temperature above the melting point of the thermoplastic material, and applying the heated sheet directly to the bombarded surface of the layer of thermoplastic material as it continues along the path of travel for adhering the sheet and the foamed material and forming a laminated member.
Dependencies are inferred from the claim text.