Effects of mechanical conditions on tearing characteristics of zipper band made of white-clay-coated paperboard (Dependency of tearing characteristics on length of connecting portions, width of band and pulling direction)

Abstract

Packaging boxes are often sealed by a paperboard based flap and also processed so as to have a zipper band (pull tab) structure near the flap. The zipper band structure is used for opening the flap by tearing zipper dash lines which are cut off by using a repeatedly nicked (perforation formed) wedge blade. There are empirically various design patterns of zipper band. In order to arrange the geometrical design parameters of zipper band, the tearing characteristics of zipper-connecting portions must be clarified. In this work, in order to reveal the tearing strength and the success rate of connecting portions (uncut zones), a length of connecting portions and a width of zipper band were widely changed and the pulling direction (attitude) of clamped end of zipper band was also changed. The relationship between the tearing strength and the across direction of cutting line to the grainy direction of paperboard was investigated. Through the experiment, it was found that in-plane de-lamination and tore protrusion occurred at the connecting portions in the band area. Since this de-lamination seemed to be related to the fault of peeling, the effects of pulling attitude (angle) of clamped end of zipper band on the success rate was discussed. As for the upper critical length of connecting portions, at which the success rate became zero, the upper bound tearing strength was gotten and related to the Elmendorf value.

Keywords

• zipper pull tab
• nick
• peeling
• delamination
• tearing strength
• grainy
• fiberboard