Water resistant paper based on natural rubber latex from Hevea brasiliensis and butyl stearate hydrophobic coating for packaging applications

Abstract

Sustainable hydrophobic coatings on paper have become increasingly important due to the high demand for environmentally friendly materials. In this study, a novel sustainable hydrophobic coating was developed by combining natural rubber latex (NRL) and butyl stearate (BS). The NRL acts as binder and hydrophobic agent, while the butyl stearate improves the hydrophobicity of the coating. Different coating formulations containing 0–50 wt% BS were applied to the paper using a simple bar-coating method at a constant thickness, and the hydrophobic properties were evaluated by using contact angle, Cobb and water vapour transmission rate (WVTR) measurements. The lowest WVTR value was 3.428 g/cm2. Day, obtained when NRL coated, and WVTR of 4.405 g/cm2.day was obtained with an addition of 50 wt% BS, lower than the uncoated paper (5.485 g/cm2.day). All the formulations promoted a remarkable decrease in water absorption (Cobb30 values decreased from 128 g/m2 to 0.8 g/m2, and Cobb60 values decreased from 134.4 g/m2 to 0.7 g/m2). Results showed that the coating effectively reduced the surface energy of the paper, resulting in a high contact angle of 90.6° and increased hydrophobicity. Furthermore, the NRL and butyl stearate coating demonstrated good mechanical properties, suggesting its potential as a sustainable and effective alternative to synthetic hydrophobic coatings. Overall, this study presents a promising approach for the development of sustainable hydrophobic coatings on paper, which can have significant environmental and economic benefits.