Ultrafine powder coatings are one of the development directions in the powder coating industry, as they can achieve thin coatings with good leveling and high surface smoothness comparable to liquid coatings. Compared to regular coatings, they experience a higher sensitivity to any incompatibilities, e.g., filler from coating components. The properties of fillers play a great role in the performance of coating films. Aluminum trihydrate (Al(OH)₃) is a well-known filler in solvent-based coatings and other polymer industries. To study and evaluate the performances of Al(OH)₃ in ultrafine powder coatings, a popular filler, barium sulfate (BaSO₄) is used for comparison. Both fillers are added in ultrafine powder coatings based on two of the most commonly used resin systems (polyester-epoxy and polyester). The differences of physical and chemical properties between both fillers have significant influences on several properties of powder paints and coating films. The polar groups (hydrogen bond) in Al(OH)₃ result in the strong interaction between inorganic filler and organic polymer matrix, thus decreasing the molecular network mobility and influencing the chain formation, which is verified by differential scanning calorimetric (DSC). The bed expansion ratio (BERs) of powder paints incorporated with Al(OH)₃ are much higher than those with BaSO₄, which indicate more uniform gas-solid contact during the spraying process. Samples with Al(OH)₃ exhibit much lower specular gloss at 60°, which are expected to achieve remarkable matting effects. Superior corrosion resistances can be observed for almost all the coated panels incorporated with Al(OH)₃ in contrast to those with BaSO₄. Other aspects are slightly influenced by the difference between the two fillers, such as the angle of repose values (AORs) of powder paints, the impact resistance and flexibility of coating films.

Aluminum trihydrate (ATH) is one of the most widely used fillers in solvent-borne coatings and polymer industries. To investigate its performance in powder coatings, four different pigment to binder ratios (P/B) were used in respect to different ATH concentrations in four most widely used resin systems (epoxy, epoxy-polyester, polyurethane and polyester). The angle of repose (AOR) and specific gravity of powder paints increase accordingly with ATH concentration. The mechanical properties, corrosion and UV resistance performances of coating films are enhanced or only slightly decreased with the addition of ATH. Pencil scratch hardness increase significantly with the increase of ATH content. Impact resistance decreases within 5% of the initial resistance at the maximum ATH loading. There is a slightly decrease in corrosion resistance performances of less than 2 mm of failure at scribe in all formulations. The incorporation of ATH has slight effect on the UV resistance performance of all the samples. Moreover, the matting effect of ATH is observed for all the resin systems, especially epoxy, with the specular gloss decreasing more than 70% at P/B of 0.75.

3-hydroxybutyraldehyde (3-HBA) is mainly employed to synthesize 1,3-BDO (1,3-butanediol), which is one of the most important components in cosmetics moisturizers. In this study, a series of composite oxide catalysts were prepared by bringing alkaline earth metal Ca and rare earth metal La to the composite oxide MgO/Al₂O₃, which were made through the co-precipitation method. These catalysts were applied in the synthesis of 3-HBA through acetaldehyde (AcH) condensation. The structure, texture, and acidic properties of these catalysts were characterized using various characterization methods, and the effects of catalyst composition, reaction temperature, reaction pressure, and residence time on the conversion of AcH were investigated as well. The results showed that the introduction of Ca and La weakened the acidic property and enhanced the basic property, which favored the AcH condensation to synthesize 3-HBA. At a temperature of 20 °C, pressure of 200 kPa, and residence time of 70 min, 0.5%La-2.3%Ca-2MgO/Al₂O₃ exhibited a better catalytic activity, and the conversion of AcH reached 95.89%. The selectivity and yield of 3-HBA were 92.08% and 88.30%, respectively. The stability test indicated that the high AcH conversion could be maintained for 5 h.

Agitator reactors are widely used in chemical production processes, and their structural design has a significant impact on power consumption. Therefore, this study performs numerical simulations of multi-stage cup-shaped paddle agitators with different geometric parameters, and discusses in detail the effects of the paddle spacing (S/H), the ratio of the upper paddle length to the reactor radius (L_s/R), the ratio of the lower paddle length to the reactor radius (L_x/R), and the ratio of the upper to lower paddle lengths (L_s/L_x) on the reactor’s power characteristics and internal flow field. Equations were derived to relate the power number (Np) to parameters such as Re, L_s/R, and L_x/R. The study found that, at the same Reynolds number, torque exhibits a slight upward trend as the paddle spacing increases; the best mixing effect is achieved when S/H is 0.333. Based on this pitch, when L_s/R, and L_x/R exceed 0.67, the mixing process fails to form a stable and complete radial circulation; when L_s/R and L_x/R are less than 0.53, the high-velocity zone in the flow field decreases, leading to the formation of dead zones. Therefore, selecting a multi-stage cup-shaped impeller with an L_s/R value of 0.53, an L_x/R value of 0.53, and L_s/L_x of 1 can achieve better mixing results with lower power consumption. These findings provide a reference for the energy-efficient optimization design of multi-stage cup-shaped impeller mixers in industrial applications.