Characterization and Utilization of Eziulo Clay as an Extender in Emulsion Paint Formulations

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A series of emulsion paint samples were prepared using Eziulo clay as an extender, commercial whiting, and titanium dioxide (TiO2). The clay that was calcined at 850oC and sieved to three particle sizes (0.075, 0.100 and 0.150 mm) was incorporated into emulsion paints at varying amounts ranging from 5% - 32% of the total extender and pigment in the paints. Poly (vinyl acetate) was used as the binder while distilled water served as the solvent. The Eziulo clay which consisted mostly of silica (63.30%), alumina (19.40%), and iron (III) oxide (2.10%) had the following properties: pH (6.67), specific gravity (2.47) and oil absorption (34.30 g/100 g clay). The colour and solubility of the clay in dilute hydrochloric acid, acetic acid, sodium chloride solution, methanol and distilled water were generally unaffected either in the cold or when heated expect for the slight solubility observed in methanol. The clay formulated paint samples exhibited higher viscosity (7.0 - 7.80 poise) than the paint sample without Eziulo clay (6.60 poise). Conversely, the pH and specific gravity of the paint sample without Eziulo clay were higher than those of paint sample containing the clay. The surface and hard dry times of the formulated paint samples were greater than that of the paint sample without Eziulo clay. The determined surface dry times were within the range, 16 - 18 min, irrespective of clay content and particle size. The hard dry times of the formulated paint samples were found to reverse with increases in clay content. The paint dry film flexibility was unaffected by the incorporation of clay, irrespective of the amount and clay particle size. The emulsion paint dry films exhibited decreases in film adhesion to substrates with increases in clay content, and increases in film adhesion with increases in clay particle size. The paint dry films did not exhibit any chalking tendency, were resistant to fungal attack, and passed the water drop test. The present study has demonstrated the utility of Eziulo clay in emulsion paint formulations which should justify its use in the surface coatings industry.