Rectangular paperboard package and method of making same

Abstract

A liquid tight rectangular paperboard container is provided with a separate opening tab secured to the top panel thereof which enables the package to be opened to provide a fully open top. In particular, an elongate plastic window is formed along the front fold line connecting the top and front panels of the package, and has ends connected to spaced apart arcuate shaped perforated lines extending to the rear corners of the top panel. In the construction of the package, the opening tab is first ultrasonically welded to the outside surface of the package blank, and then the window section is pressed against and welded to the inside surface of the tab. A slit which is formed in the window enables any air trapped between the window and the tab to escape during the welding operation. The package also includes other unique features such as a side sealing flap structure, a bottom panel sealing structure, and a unique blank structure. Also, the particular paper supply roll and the tab supply roll from which the package is constructed have a unique structure.