Development of a polyurethane sealing gasket with excellent sealing and opening properties

Abstract

Alternative materials to replace the currently used poly(vinyl chloride) (PVC) plastisols as sealing gaskets for use in wide-mouth glass jars have been desired. In this study, we propose a novel urethane-based polymer as a better replacement for PVC plastisols. This polymer was prepared by reacting a diol with a molecular weight (MW) of 1000 g mol−1, a triol with an MW of 500 g mol−1 and an aliphatic diisocyanate adduct with MW of 430 g mol−1. When additives, such as hollow particles as a blowing agent and lubricants, were incorporated into this urethane polymer, the resulting material exhibited a rubbery plateau with a low modulus over a wide temperature range, from a temperature 100 °C. These properties favorably support this material for use as a sealing gasket owing to its remarkable sealing and opening characteristics. In the cross-sectional view of sealing gasket, the urethane sealing gasket is composed of urethane-based polymer as a matrix and heat-expandable hollow particles as independent air bubbles. The polyurethane matrix has a crosslinking structure with aliphatic diisocyanate aduct, PTMG, and bi- and trifunctional polyester pre-polymers. Not only by adjusting the mechanical properties with the blowing agent but also by being localized lubricants with talc on the surface, both excellent sealing and opening properties could be realized.