Superhydrophobic paper coating containing nonconventional clay

Abstract

Hydrophobic clay fillers have not been widely used in dispersion coatings for linerboard because of the difficulty of dispersing them in water. This work investigated whether hydrophobic clay can be used as filler in barrier dispersion coatings. Hydrophobic clay was compared with conventional clay in terms of coating consolidation, structure, wetting, and barrier performance. All coatings were applied to linerboard sheets made using a laboratory dynamic sheet former. The coated linerboards were examined using scanning electron microscopy and Raman spectroscopy, and were characterized with respect to water absorption, vapor transmission rate, and contact angles. The results show that a coating containing hydrophobic clay provides a superhydrophobic character to paper; i.e., a high water contact angle (150°) and relatively low water absorption. Raman mapping of cross-sections revealed that the latex distribution is uniform in the presence of either conventional clay or hydrophobic clay, and that the distribution of hydrophobic clay tends to be more uniform than conventional clay, which might reflect good mixing and consolidation of hydrophobic clay.

A Review of Thermoplastic Composites Vapour Permeability Models: Applicability for Barrier Dispersion Coatings

“…3,4 However, their hydrophobic nature and the difficulty of dispersing them in water are often linked with use of dispersants. 11 Besides dispersants, several others additives are normally used to facilitate the coating processing (e.g. thickeners, anti-foamers, surfactants, alkalis, waxes, co-binders such as starches and water retention agents).…”

“…thickeners, anti-foamers, surfactants, alkalis, waxes, co-binders such as starches and water retention agents). 1,3,11 The quantity of the fillers used for coating formulation must be lower than the critical pigment (filler) volume concentration (CPVC). This parameter represents the concentration of binder (polymer) that is just enough to coat all the filler particles and fill the intervening spaces.…”

“…Hydrophobicity in talc or hydrophobic clays usually contributes to the reduction of moisture permeability in barrier coatings for paper . However, their hydrophobic nature and the difficulty of dispersing them in water are often linked with use of dispersants . Besides dispersants, several others additives are normally used to facilitate the coating processing (e.g.…”

“…Besides dispersants, several others additives are normally used to facilitate the coating processing (e.g. thickeners, anti‐foamers, surfactants, alkalis, waxes, co‐binders such as starches and water retention agents) …”

Surface Chemistry of Oil-Filled Organic Nanoparticle Coated Papers Analyzed Using Micro-Raman Mapping

“…14 Other coatings with modified clays were analyzed with Raman spectroscopy, showing that the distribution of hydrophobic clay tends to be more uniform than conventional clay. 15 The Raman microscopy allowed to visualize the lateral distribution of chemical and physical composition of a paper coating with high spatial resolution. 16…”