Journal of Coatings Technology and Research最新文献

With the continuous growth of the inkjet printing market, it has become particulary important to endow dye thermal transfer paper with fast-drying performance and fine transfer effect. In order to achieve this goal, the nanohybrid materials of HNTs/MSN (halloysite nanotubes/mesoporous silica) were prepared by Stöber method and in situ growth method, and then, the thermal sublimation transfer papers coated with CMC/MSN, CMC/HNTs, and CMC/HNTs/MSN were prepared, respectively. Characterizations of MSN, HNTs, and HNTs/MSN were conducted using TEM, FTIR, XRD, XPS, and BET techniques, followed by testing the properties of the coated papers. The results showed that the HNTs/MSN nanohybrid materials were formed by deposited MSN on HNTs with the Stöber method and in situ growth method. Among the three types of papers, CMC/HNTs/MSN paper exhibited the best comprehensive performance with fast-drying performance and fine transfer effect. Therefore, CMC/HNTs/MSN can be used as a novel type of thermal transfer paper coating with fast ink drying speed and fine transfer effect.

To determine the feasibility of crosslinker-free epoxy systems as an applied coating solution, this study investigated the cure-by-design behaviors and functional performance of anionically catalyzed crosslinker-free epoxy functional coatings. A fusion boned epoxy (FBE) powder platform was utilized, and formulation index (FI)-oriented optimizations were performed, with the FI extended to infinity (or ∞), which corresponds exclusively to 100% epoxy self-crosslinking from an applied chemistry standpoint. Depending on the catalyst type and loading, the cure kinetics and rheology of these homogeneous crosslinker-free systems varied significantly from those of heterogeneous crosslinker-containing coatings. In addition to thermal curing responses (including viscoelastic gelation and vitrification), the structural properties, particularly glass transition temperature (T_g), flexibility, cohesive toughness, impermeability, and adhesion, are closely correlated to the T_g-capability or -potential of their formulations, as well as the chemical structures, molecular weights (MWs), epoxy equivalent weights (EEWs), and functionality (f) of the underlying epoxy resins or monomers. Other interesting findings, such as the concurrence and sequences of epoxy-crosslinker copolymerization and epoxy-epoxy homo-polymerization by differential scanning calorimetry (DSC) exothermic profile analysis, are reported and explained.

Microphase separation within the polyurethane (PU) matrix is caused by thermodynamic incompatibility between the soft and hard segments and the movement of them. Although degree of phase separation (DPS) is a sensitive and important parameter and reflects the formation of the internal hydrophobic network structure, research on the relationship between DPS and the corrosion resistance performance of PU coatings is very limited. This study prepared a series of PU coatings with different soft and hard segment ratios, quantitatively calculated DPS, and analyzed the residual situation of the -NCO groups of each coating using infrared spectroscopy (FTIR). The crosslinking density (XLD) of the coatings was obtained using the swelling equilibrium method. The corrosion resistance performance of the coatings was periodically tested through salt water immersion experiments, Tafel tests, and electrochemical impedance spectroscopy (EIS). It was found that coatings with a high hard segment content have higher DPS and XLD. The samples with the highest hard segment content (sample PU3-5-10 and PU3-5-11) possessed the highest DPS values (24.28 and 41.95%) and showed the lowest corrosion current density (9.3 × 10⁻¹¹ and 3.25 × 10⁻¹¹ A/cm²) and the highest impedance values (6.22 × 10⁸ and 1.24 × 10⁹ Ω cm²) before salt water immersion; however, PU3-5-11 showed a much more rapid decline in impedance after 40 days of immersion. FTIR analysis indicated that the presence of easily hydrolyzable residual -NCO groups should be the main reason for the worsening. It was also found that the DPS of the coatings is highly correlated with their XLD, and the relationship between DPS and various corrosion resistance indicators is basically consistent with that of XLD.

Encapsulating smart nano-containers loaded with corrosion inhibitors into coating is a promising approach to functionalize micro-arc oxidation (MAO) coating. The encapsulation strategy of smart containers has a great influence on the microstructure, corrosion resistance and self-healing performance of the smart MAO coating. In order to provide a comprehensive understanding, two kinds of MAO coating encapsulated smart containers (HNT-8HQ), MAO-HNT-8HQ (1S) coating (one-step preparation in an MAO electrolyte containing smart nano-containers) and MAO + HNT-8HQ (2S) coating (pre-prepared MAO coating through an embedding nano-container processing) were prepared on AZ31 magnesium alloy. The incorporated HNT-8HQ in electrolyte can effectively reduce coating porosity and increase coating thickness. Both smart MAO coatings show considerable improvements in the corrosion resistance and a certain self-healing capacity. The post-embedding treated coating (MAO + HNT-8HQ (2S)) has better long-term durability and self-healing performance than one-step preparation coating (MAO-HNT-8HQ (1S)). The low-frequency impedance modulus (|Z|_ƒ=0.01 Hz) of MAO + HNT-8HQ (2S) coating is 1.33 times that of MAO-HNT-8HQ (1S) coating after immersion in 3.5 wt% NaCl solution for 168 h. The MAO + HNT-8HQ (2S) coating has higher impedance values than MAO-HNT-8HQ (1S) coating during the entire self-healing process. The low-frequency impedance modulus of scratched MAO + HNT-8HQ (2S) coating is 3.33 times that of scratch MAO-HNT-8HQ (1S) coating after a 72 h self-healing process.

After powders of three rare earth iodates (Ce(IO₃)₄, Ce(IO₃)₃, δ-La(IO₃)₃) were dispersed in water, the constituent ions were eluted. After filtration, polyvinyl alcohol was dissolved in the filtrated solution. Then the solution was flow-coated to form coating films on glass substrates. The obtained coating films exhibited high transmittance in the visible wavelength range. IO₃⁻ was confirmed from the IR spectra measured using the ATR method. Fine precipitates were observed in the coating. The amount was greater on the surface than inside. The coating films prepared from Ce(IO₃)₃ and δ-La(IO₃)₃ possessed high antibacterial and antiviral activities against Escherichia coli, Staphylococcus aureus, bacteriophage Qβ, and bacteriophage Φ6 in the dark. Moreover, they inactivated viruses adsorbed from the gas phase.

Fluorescent security printing inks on flexible substrates is an arena that demands consistent developments to prevent the ever increasing menace of document/product counterfeiting. Visible light is a much more accessible and safer excitation source than the commonly used ultraviolet (UV) light. In this context, a simple Schiff base 4-pyridyl-benzylidene 2,4-difluoro aniline (PBDFA) is synthesized as a colorant with significant solid-state fluorescence for preparing security ink formulation. A huge challenge lies in preparing a security ink that does not fluoresce under UV light but produces a green fluorescence when irradiated with a blue light source. Such prints would be hard to forge as compared to the existing UV luminescent security inks. The screen prints obtained on a UV dull paper substrate using the solvent-based PBDFA ink revealed good blue light excitable green fluorescence, photostability, and colorimetric, densitometric, and rub resistance characteristics.

Marine biofouling has detrimental effects on the performance and service life of ships and drilling platforms, leading to increased fuel consumption, corrosion of structural surfaces, and significant financial losses. To address these challenges, we developed epoxy coatings that incorporate graphene oxide (GO) and release copper ions (Cu(^{2+})). We carried out microalgae adhesion studies and marine bacterial adhesion experiments on the various composite coatings to examine the antifouling performance of the composite coatings. Additionally, we investigated the underlying mechanisms responsible for the effects of GO and Cu(^{2+}). The results demonstrated the superior anti-adhesion properties of GO. The amount of microalgae adhering to the GO modified epoxy coating was only 13% of that adhering to the epoxy resin coating. Moreover, no microalgae adhesion was observed in the microalgae adhesion assay for the GO/Cu(_{2})O hydrogel modified epoxy composite coating (GCHMC). Additionally, we observed a sustained release of Cu(^{2+}) from the GCHMC for over 100 days, as indicated by the Cu(^{2+}) release trend. Therefore, the GCHMC effectively showcased its long-lasting marine antifouling properties.

Using nanocontainers filled with corrosion inhibitors is an efficient strategy to create a high-performance coating that protects metals from corrosion. In this paper, Metal organic framework (MIL-88) was synthesized and loaded with a sustainable and eco-friendly corrosion inhibitor, 2-chloromethylbenzimidazole (2-CBI). The 2-CBI@MIL-88 was used as a nanofiller to prepare an epoxy resin composite coating. The results showed that the corrosion inhibitors in 2-CBI@MIL-88 were released sustainably in an acidic 3.5 wt% NaCl solution. Notably, the |Z|_0.01 Hz of the intact EP + 1% 2-CBI@MIL-88 was significantly higher than that of EP, while the |Z|_0.01 Hz of scratched EP + 1% 2-CBI@MIL-88 increases upon immersion in a 3.5 wt% NaCl solution, demonstrating the excellent self-healing ability. Overall, incorporating 2-CBI@MIL-88 into epoxy coatings offers a promising approach for enhancing the corrosion resistance of steel structures.

In order to fully utilize the whole spectrum of UV–Vis light and eliminate the problems of organic photoinitiators in the photo-curable coatings, inorganic composited photoinitiators of ZnO and Fe₂O₃ nanoparticles (NPs) were prepared and added into the photo-curable waterborne polyurethane acrylates. The inorganic composited photoinitiators utilized both the ultraviolet and visible light, which easily extended the light absorption range of each photoinitiator of ZnO and Fe₂O₃ NPs. Fourier transform infrared spectroscopy, scanning electron microscopy, and ultraviolet–visible spectrophotometer were used to characterize the chemically composited particles, physically mixed particles, and their photo-curable coatings. Comparison with the pure waterborne polyurethane acrylates, better photoinitiation effect, light conversions, and mechanical properties of the photo-cured films were obtained when the chemically composited photoinitiators of ZnO and Fe₂O₃ NPs were added with a molar ratio of 1:1. The photo-curing kinetics characterized by the UV–Vis and FTIR spectroscopy also proved their improved synergistic photoinitiation effects. This study demonstrated that the chemically composited photoinitiators of ZnO and Fe₂O₃ NPs were a prospective solution to the complete utilization of illumination light during the conventional photo-curing processes.

Surface modification of metal oxide nanoparticles can enhance their dispersibility in polymer matrix. In this study, the zinc oxide (ZnO) nanoparticles (NPs) were organically modified by coupling agent as isopropyl tri (dioctyl phosphate) titanate (KR-12) with the initial content of 3 wt.% (in comparison with ZnO NPs weight). The characteristics of modified ZnO (m-ZnO) NPs, namely chemical changes, zeta potential, morphology, and thermal behavior, were evaluated using IR spectroscopy, DLS, SEM, and TGA methods, respectively. The obtained results suggested that ZnO NPs were modified successfully with KR-12 coupling agent. In comparison with the unmodified ZnO (u-ZnO) NPs, the m-ZnO NPs had additional functional groups and there were changes of some properties such as hydrophobic property, surface charge, and thermal stability of m-ZnO NPs. The m-ZnO NPs could disperse in epoxy resin better than the u-ZnO NPs. Therefore, the m-ZnO NPs improved the mechanical properties, chemical resistance, thermal stability, and anticorrosion protection ability of epoxy resin coating. The abrasion resistance and the adhesion of epoxy coating containing 2 wt.% m-ZnO NPs were increased about 40% and 54%, respectively. The bending resistance of epoxy resin was also enhanced, and the anticorrosion resistance of coatings was improved in the presence of m-ZnO nanoparticles.