Effects of Acid Types and pH Levels on the Glass Stain Retardability and Properties of Glass Interleaving Paper

Abstract

The objectives of this study were to determine the effects of treated acid and the pH level of interleaving paper on its glass stain retardability and properties. Handsheets of interleaving paper were treated with two factors consisting of acid type and pH level.  Two types of weak acid and one strong acid provided by Teppatana Paper Mill Co., Ltd., i.e., TEP01 and TEP02, and TEP03, respectively, were used for treating the handsheets to achieve pH 4.0, 5.0 and 6.0.  The treated handsheets were examined for their glass stain retardability in a glass warehouse with an average temperature of 32 ^oC and relative humidity of 92%.  Glass stain occurrence was observed every 30 days until 120 days.  Handsheet properties such as apparent density, tensile strength, air permeance, brightness and opacity were also assessed in accordance with the TAPPI standards.  The results indicated that the handsheets treated with TEP02 at pH 4.0 showed the best performance for retarding the glass stain occurrence, i.e. there was no glass stain and no fungal occurrence at 120 days.  The mechanical and physical properties of treated handsheets were affected by the acid type and pH level possibly due to acid hydrolysis partially weakening fibers and dissolving fines in the handsheets.

Keywords: Glass stain, Glass interleaving paper, Retardability