Oil and water resistant of packaging papers

The permeability of paper and cardboard materials is extremely important for packaging safety. However, paper and cardboards have poor liquid resistance due to their naturally porous structure and the hydrophilic character of cellulose fibers. When packaging papers are exposed to liquid effects both from inside (by the product) and outside, they may become deformed and cannot fulfill their duty of protecting the product. For this reason, the resistance of packaging papers to liquids (water-oil, etc.) should be well known in order to make a selection appropriate to the content of the products. In this study, the effects of air permeability, liquid contact angle and surface energy values of various papers and cardboards used in the packaging industry on water and oil resistance were experimentally investigated. After determining the air permeability of the papers, liquid contact angle and liquid absorption measurements were carried out using the Sessile water drop method for surface wetting characterization. The surface energies of the papers were calculated depending on the liquid contact angle. Then the oil absorption of these papers was determined by measuring the time-dependent absorption of Castor oil. Differences in liquid resistance between papers were demonstrated and evaluated based on the air permeability of the papers, water contact angle, surface energy and liquid absorption. It was concluded that the wettability and surface energy of papers are the determining factors in water absorption, while air permeability is the determining factor in oil absorption.