Barrier Dispersion-Based Coatings Containing Natural and Paraffin Waxes.

Julia Woch,Justyna Chrobak,Edyta Małachowska,Aneta Lipkiewicz,Kamil Korasiak,Piotr Przybysz,Marcin Dubowik,Jolanta Iłowska

doi:10.3390/molecules27030930

Abstract

Petroleum, synthetic, and natural waxes have been used as hydrophobic bases for dispersions intended for use as barrier coatings for packaging paper. Oil-in-water dispersions with alkaline pH were prepared by a two-step homogenization procedure containing paraffin wax, with various characteristics, the Fischer–Tropsch synthesis product or beeswax. The size of the dispersed particles determined by dynamic light scattering depended on the type of hydrophobic base used and was in the range of 350–440 nm. The ability of dispersion particles in aggregation driven by electrostatic attraction, evaluated by Zeta potential analysis by electrophoretic light scattering, was from −26 to −50 mV. Static multiply light scattering was used for 30 days of stability assessment and helped to select the dispersion with a Sarawax SX70 wax base as the most stable. Dispersions were further used for coating the backing of kraft paper by the Meyer rod method. Coated paper with an applied coating of 6 g/m2 had very good hydrophobic properties (Cobb60 < 4 g/m2), sufficient strength properties, and air permeation, which enabled its application as a packaging material. The dispersions based on Sarawax SX70 wax were evaluated as the best coating for Mondi ProVantage Kraftliner 125 g/m2 backing paper. Good hydrophobic properties and strength properties indicate the possibility of using the SX70-based wax dispersion coating as a replacement for PFAS coatings in some applications.

Highlights

Paper packaging is a quickly growing for the paper industry
Paper packaging materials made from cellulosic fibers have the advantages of large availability, renewability, biodegradability, and recyclability [1]
Due to the hydrophilic character of the cellulose fibers arising from the multiple hydroxyl groups, packaging paper grades are hydrophobized to reduce penetration and wetting by water [7,8]

Summary

Introduction

Paper packaging is a quickly growing (and extremely promising market) for the paper industry. Paper packaging materials made from cellulosic fibers have the advantages of large availability, renewability, biodegradability, and recyclability [1]. Considering the functional properties of paper packaging, one of the major requirements for packaging papers is the need to provide a moisture barrier [3]. In the paper manufacturing industry, this treatment is frequently performed throughout the coating process, allowing the control of penetration of liquids into the paper [9]. In the paper packaging industry, kraft paper is commonly used because of its low cost of production. Kraft paper has to be coated with a good moisture barrier material (because of the high porosity and large pore size in such paper [10,11]) that will not create problems in recycling and will have minimal impact on its cost [12,13]

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Discussion

Conclusion