Studies on Semi-crystalline Poly Lactic Acid (PLA) as a Hydrophobic Coating Material on Kraft Paper for Imparting Barrier Properties in Coated Abrasive Applications

Abstract

This study investigated and explored the possible use of bio-based Poly lactic acid (PLA) as a barrier coating material on natural Kraft paper to fabricate coated abrasive products and to replace the conventional, non-biodegradable, synthetic polymer based barrier coating materials. PLA was coated on the Kraft paper using a solution coating process. The barrier properties of the PLA-treated Kraft paper were accordingly tested for application as a backing material in coated abrasive products. The concentration of PLA in solution was systematically increased from 5 wt% to 25 wt%. The coating thickness and coating weights were increased quantitatively with increasing solution concentrations. The morphology of the coating was characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), contact angle, and surface roughness measurements. The mechanical properties of the PLA coating applied Kraft paper were quantified by measuring the tensile strength, bursting strength, air porosity and Cobb value in order to find its suitability as coated abrasive product. The thermal analysis carried out using DSC scan indicated the semi-crystalline nature of PLA. The coating’s analysis for air and water resistance indicated that the air and water resistance increased with increase in PLA coating thickness. The data from different studies revealed that the PLA coating with a coating weight of 9 g m−2 appeared to be the most ideal concentration over the untreated or other lower PLA g m−2 treated backing materials and proved to possess superior overall barrier properties that are essentially needed for the fabrication of coated abrasive products.