Novel Die Design Using Polytetrafluoroethylene and Polyoxymethylene Creasing Rules for Industrial Die Cutting and Creasing of Dispersion-Coated Folding Boxboards

Abstract

The flatbed die-cutting principles used to convert sustainable dispersion-coated paperboards for food packaging have remained largely unchanged for decades, despite persistent issues with coated-surface integrity after creasing. To improve the convertibility of such materials, this study developed novel die incorporating low-friction plastic creasing rules for industrial die cutters. The die comprised conventional uncoated steel creasing rules as the control condition and interchangeable creasing-rule inserts machined from polytetrafluoroethylene (PTFE) or polyoxy-methylene (POM). The rule contours were surrounded by conventional steel knives to produce standard folding-carton blanks from three dispersion-coated paperboards. The coated surface integrity of the materials was evaluated by measuring the oil and grease resistance (OGR) and performing scanning electron microscopy before and after conversion. The results indicated that the highest OGR was obtained for two paperboards creased with PTFE rules. Die cutting with POM rules improved creasability at specific test points; however, the average performance was comparable to that of steel rules. The third paperboard was particularly prone to damage, precluding a comparison across rules. As the PTFE-based toolset demonstrated superior performance on an industrial die cutter, future research should examine whether die design can be simplified by applying a low-friction PTFE coating to conventional steel creasing rules.