A zipper pull tab is used to open a flap by tearing the zipper dash lines, which are produced by using a nicked blade. There are various empirical design patterns of the zipper pull tab depending on the geometrical features. In order to arrange and classify these various patterns of the zipper pull tab, the tearing characteristics of the zipper-connecting portion must be clarified, while changing some representative parameters, such as the pitch of nicks and the profile of the entry guide parts. In this work, in order to reveal the effect of the guiding route on the tearing characteristics, several fundamental patterns were chosen and the tearing tensile force response and breaking modes of the connecting portion were experimentally investigated while varying the geometric parameters and the grain direction of paperboard. Appropriate guiding routes embedded in the band zone contributed to the cutoff of connecting portions when the perforation of the zipper band was across the grain direction of the paperboard. The success rate of tearing connecting portions was statistically analyzed with respect to the pattern of the guiding route. It was found that the inhibition of delamination after passing through the torn zone was necessary to successfully cut off the connecting portions.

Coated-recycled paperboard is considered to be a fundamental material for the packaging industry due to its advantages such as high strength-to-weight ratio, high surface smoothness, printability, sustainability, recyclability, and so on. To convert paperboard into a packaging container, a raw paperboard is first printed at a printing line. Then, it is subjected to cutting and creasing processes (Kirwan, 2013). The stripped blank is folded and glued to obtain a packaging carton, the structure of which is designed in several styles (Kirwan, 2013). For examples, there are a seal end, tuck top auto bottom, tuck end, sleeve, lock corner tray, walker lock tray (All packaging company, 2016). Since a closed packaging box is considered to be easily or smoothly opened by customers, a sort of tearing band (zipper pull tab), which is formed in the die-cutting process, is often designed and implemented on the packaging box flap. The zipper band for opening a box flap normally consists of two parallel dashed lines, which are perforation for tearing. Although such a zipper band is widely used for opening a sealed carton, there seemed to be not any standardized cutting patterns of zipper band yet. There are empirically various cutting patterns of zipper band for each manufacturer. However, there are not any public designing methods and theoretical discussion on mechanics of tearing characteristics of zipper band. Regarding the failure behavior of paper, the mode III tear test as the Elmendorf test is known and standardized