Plastic sheet with a surface treated to enhance adhesion and method of making such sheets
AssigneeR. R. Donnelley & Sons Company
InventorAlvin J. Hahn
Life of this patent
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Abstract
A sheet of thermoplastic material has a planar surface treated to enhance adhesion of paper thereto by means of an adhesive of the class consisting of animal glue and water base adhesives as used in book binding. The sheet is passed beneath a heated diamond knurling roll at a temperature and pressure, and at a rate to produce a dwell time, which are controlled to form in said planar surface a continuous pattern of small, shallow recesses separated by inter-recess planar areas of said surface, and a raised rim of the thermoplastic material bordering each of said recesses and projecting above the planar areas, a large percentage of said rims having at least a part of their outer periphery overhanging a portion of the adjacent inter-recess planar area.
Claims10
A sheet of thermoplastic material which has had a planar surface treated to enhance adherence of paper thereto by means of an adhesive of the class consisting of animal glues and water base adhesives, said surface being characterized by a continuous pattern of small, shallow recesses separated by inter-recess planar areas of said surface, and a raised rim of the thermoplasitc material bordering each of said recesses and projecting above the planar areas, a large percentage of said rims having at least a part of their outer periphery overhanging a portion of the adjacent inter-recess planar area.
A method of treating a planar surface of a sheet of thermoplastic material to enhance adherence of paper thereto by an adhesive of the class consisting of animal glues and water base adhesives, said method comprising the step of subjecting said planar surface to contact under pressure from a heated member which has a continuous pattern of small, closely adjacent protuberances that displace the thermoplastic material to form in the planar surface a continuous pattern of small recesses, and controlling the temperature of said member, the pressure, and the time of contact so that said recesses are shallow and separated by small inter-recess planar areas, and so that the thermoplastic material displaced to form each recess remains as a raised rim which borders said recess and has at least a part of its outer periphery overhanging a portion of the adjacent inter-recess planar area.
Dependencies are inferred from the claim text.