BREATHABLE WATER-RESISTANT LINERBOARD COATINGS BY ELECTROSPRAYING APPLICATION

Waterproofing of corrugated packaging with wax or polyethylene hinders recyclability and so is incompatible with current socioeconomic goals of sustainability. Therefore, alternative coating technologies are sought. This study describes our feasibility study of electrohydrodynamic spraying (EHS) towards waterproofing corrugated boxes. Water resistance properties of electro-sprayed polymer-solvent solutions and latex systems air dried onto linerboard surface are reported. Optimization of spraying parameters led to observations of applied coating roughening on a nano-to-micron scale that correlated with increased water contact angle of the treated linerboard. An EHS latex formulation, compared to polymer solvent system, has shown better adhesion to linerboard. EHS application of latex produced a surface coating texture of droplets, which minimizes liquid water absorption, forming a nanopore matrix (of 3 - 50 nm diameter pores) that enabled the transmission of water vapor. Linerboard treated by EHS latex was advantageously found to be comparatively transpiring to water vapor at room temperature and refrigeration conditions, which is encouraging for commercial application of the technique.