Coating and Paint Testing

Baudys, M., et al. Chemical Engineering Journal 261 (2015): 83-87.

The performance of facade paints containing the photocatalysts TiO₂ and ZnO was evaluated through simulated weathering tests. The self-cleaning properties of acrylic paints incorporating these photocatalysts were studied using Acid Orange 7 as a model compound. Weathering was conducted in a QUV panel to simulate environmental conditions.

The initial photocatalytic activity of unweathered paints containing ZnO was significantly higher compared to those with TiO₂. However, distinct trends in photocatalytic performance emerged during weathering. For paints containing TiO₂ (P25), photocatalytic activity increased with weathering time. This enhancement was attributed to the degradation of the polymer resin, which exposed more of the embedded photocatalyst pigment to the Acid Orange 7 test solution.

In contrast, paints containing ZnO exhibited a decrease in photocatalytic activity after weathering. This decline was primarily due to the loss and/or photocorrosion of ZnO particles during the weathering process, reducing their effectiveness as photocatalysts.

These findings highlight the contrasting behaviors of ZnO and TiO₂ in photocatalytic paints under weathering conditions, providing valuable insights for the development of durable and effective self-cleaning coatings.

Trentin, Ilva, et al. "Quick test methods for marine antifouling paints." Progress in Organic Coatings 42.1-2 (2001): 15-19.

Antifouling paints are widely used to protect ship and boat hulls from fouling organisms, enhancing speed and fuel efficiency by reducing water friction. Most marine antifouling products release chemical substances to inhibit the settlement of fouling organisms, with copper serving as the primary active ingredient in combating biological fouling on ship hulls.

This study evaluated three standard types of antifouling paints:

1. Partially erodible insoluble matrix paint (a)

2. Self-polishing controlled polymer dissolution paint (ablative paint) (b)

3. Self-polishing paint with a less soluble matrix (c)

Cuprous oxide was the primary biocide in all three coatings.

To assess the biocide leaching rate and the accelerated aging level of the paints, specimens were periodically removed from their respective test tanks and temporarily submerged in 1.2 L of standardized natural seawater for 1.5 hours. The seawater was paper-filtered, adjusted to 37 ppt salinity, and maintained at 25°C.

In addition to evaluating biocide leaching, microprobe analysis was employed to quantify the amount of copper present on the paint surface of product "a". A notable reduction in the copper signal (indicated by a lower peak, highlighted with a small circle) suggested faster consumption of copper and a quicker release into the water. This analysis confirmed the accelerated aging process and provided insights into the performance and longevity of the antifouling coatings.

Bossa, Nathan, et al. Science of the Total Environment 946 (2024): 174155.

The TiO₂ pigment, composed of rutile particles, was validated using X-ray diffraction (XRD). SEM analysis revealed that the rutile particles exhibit a spherical-like shape with distinct facets characteristic of TiO₂ pigments. Measurements of 125 particles from SEM imaging determined a mean size of 178 ± 76 nm, with a size range of 35 to 444 nm. Approximately 19% of the primary particles were within the nanometer size range.

As reported by the manufacturer, the particles contain 93 wt% TiO₂ and are coated with alumina, zirconia, and an unspecified organic treatment. Thermogravimetric analysis coupled with mass spectrometry (TGA-MS) indicated a gradual mass loss of 1.5 wt% between approximately 100 and 400 °C, attributed to the decomposition of the organic coating.

The specific surface area (SSA), measured by the BET method, was 12.7 ± 1.3 m²/g (N = 2). Using a specific gravity of 4.1 g/cm³, this corresponds to a spherical average BET size of 115.2 nm.