Performance of Local Clay-Titanium Dioxide Core-Shell Extender Pigments in Alkyd Paints

The performance of local clay-titanium dioxide core-shell extender pigments in alkyd paints has been studied. The physico-mechanical properties of the prepared alkyd paints were evaluated according to ASTM measurements. The effects of various environmental and corrosive factors on the paints were also studied. The study showed that the alkyd paint samples formulated using the core-shell pigments generally had low specific gravity (1.30 – 1.38), an indication that more of the core-shell pigments can be incorporated into the alkyd paints with considerable cost savings. The dry film thicknesses of the paint samples falls within 0.24 - 0.39 mm, suggesting that the samples will perform well as anticorrosive coatings and their adhesion properties are generally good, showing that they can withstand abrasive and corrosive agents. The core-shell extender pigments formulated paint samples were observed to exhibit the best dust-free, tack-free, and through dry times compared to TiO2 paint formulation. The formulated paint samples generally performed well on exposure to rain and sunlight as well as in distilled water, 2% Na2CO3, and 2% H2SO4 with only TiO2 paint formulation exhibiting rust. The good paint performance characteristics obtainable with the core-shell extender pigments are enough evidence to justify their utilization in the surface coatings industry. The performances of these core-shell extender pigments in alkyd paints have shown that they combine the properties of both the clays and titanium dioxide, and have the potential to overcome their disadvantages.

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

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.