Thermoformable release liner
AssigneeMinnesota Mining and Manufacturing Company
InventorErlin J. Johnson
Life of this patent
Estimating the term…
Abstract
Thermoformable release liner for use in sheet products subjected to deep-draw thermoforming operations and which may be readily removed as generally one piece by hand-pulling after the thermoforming operation is completed, comprises a multilayer structure including (a) a reinforcing layer of a material that, although it is unsuitable for use as the complete release liner, provides useful properties when used as a thinner layer of the release liner, and (b) at least one additional layer adhered to the reinforcing layer to give body to the release liner.
Claims13
A contoured article comprising a drawn thermoformed base sheet, a layer of pressure-sensitive adhesive united to said base sheet, and a release liner temporarily adhered over substantially the whole area of said layer of adhesive, said liner (1) in its unelongated form requiring less than about 3 pounds per inch width tensile load to exhibit a 10 percent elongation at 325.degree.F and greater than about 3 pounds per inch width tensile load to exhibit a 10 percent elongation at 150.degree.F, (2) comprising (a) a thin thermoplastic reinforcing layer of a first material that, in its unelongated form, requires greater than about 1000 pounds per square inch tensile stress to exhibit a 10 percent elongation at 150.degree.F and can be elongated to at least 200 percent of its original length at 325.degree.F and (b) at least one bodying layer united to the reinforcing layer of a second material that can be elongated to at least 200 percent of its original length at 325.degree.F while remaining as a continuous film adhered to the reinforcing layer, and (3) being removable from the adhesive layer as a continuous sheet by hand-pulling.
A contoured article comprising a drawn thermoformed base sheet, a layer of pressure-sensitive adhesive united to said base sheet, and a release liner temporarily adhered over substantially the whole area of said layer of adhesive, said liner (1) in its unelongated form requiring less than about 3 pounds per inch width tensile load to exhibit a 10 percent elongation at 325.degree.F and greater than about 3 pounds per inch width tensile load to exhibit a 10 percent elongation at 150.degree.F, (2) comprising (a) a thermoplastic nylon reinforcing layer that in its unelongated form, requires greater than about 1000 pounds per square inch tensile stress to exhibit a 10 percent elongation at 150.degree.F and can be elongated to at least 200 percent of its original length at 325.degree.F and (b) at least one bodying layer united to the reinforcing layer of a thermoplastic material selected from polyethylene that can be elongated to at least 200 percent of its original length at 325.degree.F while remaining as a continuous film adhered to the reinforcing layer, (3) carrying a cured polymeric silicone treatment that gives the liner improved release properties, and (4) being removable from the adhesive layer as a continuous sheet by hand-pulling.
A multilayered sheet product suitable for deepdraw thermoforming operations comprising a thermoformable base sheet, a layer of pressure-sensitive adhesive united to said base sheet, and a release liner temporarily adhered to said layer of adhesive, said liner (1) in its unelongated form requiring less than about 3 pounds per inch width tensile load to exhibit a 10 percent elongation at 325.degree.F and greater than about 3.0 pounds per inch width tensile load to exhibit a 10 percent elongation at 150.degree.F, (2) comprising (a) a thin thermoplastic reinforcing layer of a first material that, in its unelongated form, requires greater than about 1000 pounds per square inch tensile stress to exhibit a 10 percent elongation at 150.degree.F and can be elongated to at least 200 percent of its original length at 325.degree.F, and (b) at least one bodying layer united to the reinforcing layer of a thermoplastic material that can be elongated to at least 200 percent of its original length at 325.degree.F while remaining as a continuous film adhered to the reinforcing layer, and (3) being removable from the adhesive layer as a continuous sheet by hand-pulling.
Dependencies are inferred from the claim text.