The utilisation of natural clays as dispersing aids in aqueous pigment dispersions

• Published in: Építöanyag (Online) no. 4; pp. 133 - 136
• Main Authors: Castillo, Joshua C, Reyes, Merry Rose A N D, Jancon, Angelica C, Dizon, Grace Marie H, Siy, Henry C, Salvador, Sonia D, Penaloza, David P
• Format: Journal Article
• Language: English
• Published: Budapest Scientific Society of the Silicate Industry 01.10.2024
• Subjects: Alkylphenol ethoxylates; Clay; Dispersants; Dispersions; Graphene; Kaolinite; Low concentrations; Metabolites; Mica; Nanomaterials; Nanoparticles; Pigments; Sedimentation & deposition; Smectites; Surfactants; Toxicity
• ISSN: 2064-4477
• DOI: 10.14382/epitoanyag-jsbcm.2024.16

The ability of natural clays to suspend particles makes them a promising candidate for use as dispersants, with potential applications in pigment dispersions. Unlike conventional dispersing agents that stabilise particles through adsorption, clays can maintain particle suspension by forming a three-dimensional network structure due to their charged surfaces. While there are reports of clays effectively dispersing various nanoparticles, to the best of our knowledge, their use as dispersing agents for pigments has not yet been explored. Clay-assisted dispersion presents a valuable opportunity for the coatings industry due to the low cost and minimal toxicity of clays. In contrast, conventional dispersants such as alkylphenol ethoxylates (APEs) are subject to increasing restrictions and scrutiny due to their high toxicity and long-term environmental persistence. Here, we report the use of clays as dispersing agents for an organic pigment. Dispersions comprising various clay specimens (smectite, mica, and kaolinite) and Pigment Yellow 138 (PY138), a yellow organic pigment, were prepared via an in-situ grinding process at both low (0.1% w/w) and high concentrations (0.5% to 5% w/w). Among the tested clays, smectite demonstrated superior colloidal stability compared to the control. At low concentrations, smectite produced the most stable dispersions, while at higher pigment concentrations, a critical threshold was observed at approximately 1.0% w/w smectite.