Tamper-evident pressure sensitive facestock labels

Claim 2

A tamper-evident film suitable for use in forming a tamper-evident pressure sensitive label having less cohesive strength than the adhesive strength of an adhesive material bonded to one surface of the tamper-evident film, the tamper-evident film having been made by a process comprising the steps of extruding a mixture comprising an incompatible blend consisting of (a) about 40% to about 70%, by weight, of a first polymer consisting essentially of at least one readily extrudable polyolefin; and (b) about 30% to about 60%, by weight, of a second polymer consisting essentially of a brittle polymer selected from the group consisting of polystyrene, polymethylmethacrylate, or blends thereof; through a die in the form of a film, and continuously extruding a suitable length of film and withdrawing the tamper-evident film such that the tamper-evident film is not broken; the film having physical properties which allow the film to be readily torn or destroyed in both the transverse and machine direction.

Claim 3

The film of claim 1, wherein the first polymer is polyethylene, polypropylene, copolymers of polyethylene, copolymers of polypropylene or blends thereof.

Claim 4

The film of claim 1, wherein the first polymer consists essentially of approximately 50% to about 70%, by weight, high density polyethylene and the second polymer consists of about 30% to about 50%, by weight, polystyrene.

Claim 5

The film of claim 1, wherein the film has a matte finish on a first surface and a smooth or glossy finish on a second surface.

Claim 6

The film of claim 1, wherein as the tamper-evident film is initially extruded from the die, a carrier film is used to lace the tamper-evident film through film extrusion equipment.

Claim 7

The film of claim 1, wherein, as the tamper-evident film is continuously extruded, lateral edges of the film are cut to form ribbons of the film which are removed at a constant tension without causing breakage of the film.

Claim 8

The film of claim 1, wherein, after a suitable length of the tamper-evident film is extruded and wound on a roll, reduced tension is placed on the film as a trailing edge of the film is being cut or indexed.

Claim 9

A tamper-evident film suitable for use in forming a tamper-evident pressure sensitive label having less cohesive strength than an adhesive material bonded to one surface of the tamper-evident film, the tamper-evident film having been made by a process comprising the steps of extruding a mixture comprising an incompatible resin blend consisting of (a) about 40% to about 70%, by weight, of a first polymer consisting essentially of at least one readily extrudable polyolefin; and (b) about 30% to about 60%, by weight, of a second polymer consisting essentially of a brittle polymer selected from the group consisting of polystyrene, polymethylmethacrylate, or blends thereof; through a die in the form of the tamper-evident film, wherein as the tamper-evident film is initially extruded from the die, a carrier film is used to lace the tamper-evident film through film extrusion equipment; and, continuously extruding a suitable length of film and withdrawing the tamper-evident film such that the tamper-evident film is not broken; the film having physical properties which allow the film to be readily torn or destroyed in both the transverse and machine direction.

Claim 10

A tamper-evident film suitable for use in forming a tamper-evident pressure sensitive label having less cohesive strength than an adhesive material bonded to one surface of the tamper-evident film, the tamper-evident film having been made by a process comprising the steps of extruding a mixture comprising an incompatible resin blend consisting of (a) about 40% to about 70%, by weight, of a first polymer consisting essentially of at least one readily extrudable polyolefin; and (b) about 30% to about 60%, by weight, of a second polymer consisting essentially of a brittle polymer selected from the group consisting of polystyrene, polymethylmethacrylate, or blends thereof; through a die in the form of the tamper-evident film, wherein as the tamper-evident film is initially extruded from the die, a carrier film is used to lace the tamper-evident film through film extrusion equipment; and, continuously extruding a suitable length of film and withdrawing the tamper-evident film such that the tamper-evident film is not broken; the film having physical properties which allow the film to be readily torn or destroyed in both the transverse and machine direction.

Claim 11

The tamper-evident film of claim 8, wherein the first polymer is polyethylene, polypropylene, copolymers of polyethylene, copolymers of polypropylene or blends thereof.

Claim 12

The tamper-evident film of claim 8, wherein the first polymer consisting essentially of about 50% to about 70%, by weight, high density polyethylene and the second polymer comprises about 30% to about 50%, by weight, polystyrene.

Claim 13

The tamper-evident film of claim 8, wherein the tamper-evident film has a matte finish on a first surface and a smooth or glossy finish on a second surface.

Claim 14

The tamper-evident film of claim 8, wherein the process further comprises cutting lateral edges or ribbons of film from the film as the tamper-evident film is continuously extruded, and removing the ribbons of the tamper-evident film at a constant tension whereby the tamper-evident film is continuously extruded without causing breakage of the tamper-evident film.

Claim 15

The tamper-evident film of claim 8, wherein the process further comprises winding a suitable length of the tamper-evident film into a roll of film, and reducing tension on the tamper-evident film as a trailing edge of the film on the roll is being cut or indexed.