Method and Apparatus for Evaluating Fold Endurance and Surface Adhesion of Sheet Materials

Forest Service

This invention facilitates testing the endurance of flexible sheets, such as paper, and the adhesion of surface treatments, coatings, and print to the surface of such sheets, as well as the bonding of multi-layer sheets. Specifically, the invention creates a small radius fold in a sheet specimen, and restrains the specimen with a pressure differential. The fold can be shifted progressively across the sheet in a controlled manner by manipulating the sheet specimen. This invention is a method and apparatus for testing the flexural durability and structural integrity of sheet materials, and the adhesion and durability of surface treatments such as printing and coatings, which permits testing without the use of rollers or rubbing surface contact, and permits testing with bend radii approaching zero. It overcomes the shortcomings of earlier devices and represents a significant advancement in the art. The invention represents a breakthrough in timely testing of durability and structural integrity in currency and other paper, removing a barrier to the development of effective quality control.

Reference:

Please refer to Patent Number 5,566,570, which issued October 22, 1996.