Journal of Coatings Technology and Research最新文献

In this study, epoxy resin containing hydrazone groups was cured with polyetheramine (Jeffamine D2000) and nanoparticles (carbon nanotubes, graphene, and fullerenes) to obtain new epoxy nanocomposite coatings as alternatives for epoxy coatings for metallic surfaces. In the initial stage, hydrazone was synthesized, and the epoxidation reaction was carried out with EPC (epichlorohydrin). Subsequently, the newly formulated hydrazone-based epoxy resin was cured with polyetheramine (Jeffamine D2000) and nanoparticles (carbon nanotubes, graphene, and fullerenes) at varying temperatures (25–120°C) to yield novel epoxy nanocomposite coatings. The characterization of the resins and coatings was conducted through a combination of nuclear magnetic resonance, Fourier transform infrared spectroscopy, and differential scanning calorimetry (DSC) analysis. The DSC results indicate that the cured films have glass transition temperatures approximately 107°C. The amine-cured epoxides were obtained with fairly high Tg values and good thermal stability. In addition, the mechanical properties (hardness, impact resistance, and adhesion) of the new hydrazone-based organic nanocomposite coatings obtained in this study were also examined. Furthermore, a comparative analysis was conducted between the thermal and mechanical properties of the novel epoxy coatings and their nanoparticle-containing derivatives, thereby unveiling the effect of nanoparticles on the properties of the coatings.

The interlayer adhesion of multilayer fouling release coating (FRC) systems is crucial for their durability and long-term performance. However, characterizing the adhesion of such systems, particularly the silicone-based topcoats, represents unique challenges due to their nonstick surface properties, low mechanical strength, and comparatively weak interlayer adhesion. Consequently, common adhesion test methods often fail to provide consistent and reliable measurements, leading industry to adopt more unconventional methods, which, however, require a high examiner expertise and do not provide quantitative adhesion values. In the present study, the well-known pull-off adhesion method was optimized for the quantitative adhesion measurements of multilayer FRC systems. Key optimizations comprised the selection of a suitable glue, the correct preparation of the test area and the bonding of the dolly, the pull-off rate, and a more accurate failure pattern assessment using digital image analysis. The reported pull-off method procedure allowed reproducible adhesion characterization and differentiation of the tested FRC systems. Additionally, changes in the adhesion properties and the weak spots due to altered overcoating intervals and seawater immersion were detected. By following the procedure and guidelines provided in this study, the pull-off method can be effectively applied as an objective and quantitative adhesion test for multilayer FRC systems.

Fast UV-curable coatings were prepared through thiol-ene reaction in 10 s, and their waterproof performance was evaluated in different aqueous conditions. The FTIR spectra showed that UV polybutadiene (PB) coatings could be successfully prepared by using mercaptan pentaerythritol tetra (3-mercapto propionate) (PETMP) as the crosslinking agent reacting with maleic anhydride-grafted polybutadiene under photo initiator. Their gel content increased from about 78–92% with the addition of PETMP from 10% to 20%, and then, this increment was less than 2% with the addition of PETMP from 20% to 30%. Their water absorption rate decreased from about 7%–4% with the addition of PETMP up to 20%−25% after 240 h immersion in DI water. The coating containing 25% PETMP demonstrated a significant cleanliness relative to that of plywood and the other coatings as observed from the stain flushing test. The EIS impedance after 96 h immersion revealed a great enhancement in corrosion resistance with the addition of PETMP at about 20%–25%, while the decline in impedance for the coating with 30% PETMP implied the probable aggregation of excessive PETMP; these were confirmed by the semi-immersion test in which the sample containing 20% PETMP exhibited much better salt water resistance than that of the other samples after 168 h immersion in 3.5% NaCl solution. An appropriate addition of PETMP at around 20%–25% resulted in a high crosslinking degree that enhanced waterproof performances of UV-cured PB coatings in DI water, stain water, and salt water. This study provides valuable reference in designing fast UV-curable coatings with good water resistance used as electronic packaging sealants, flexible protective coatings, and so on.

Numerous studies have discussed the impacts of VOCs emissions from coatings on ground-level ozone in China. However, the VOCs contents and species of housing refurbishment coatings need to be further investigated to understand the potential contribution of VOCs to air pollutants and health risks. This study has collected 78 representative coating samples from e-commerce platforms and local building material markets according to typical Chinese consumer behavior. The VOCs compositions of those coatings have been identified by gas chromatography and compare with the limit values in compulsory national standard of industrial protective coating. The analyses suggest that multiple-use housing refurbishment coatings are remarkably higher in contents of total VOCs and PAHs than traditional industrial coatings. VOCs contents and species in coatings vary by both package and solvent categories. Solvent-based coatings tend to have higher VOCs than waterborne coatings, while the VOCs contents in spray can packages are greater than those of bucket packages. Among solvent-based coatings, benzene derivatives are in full compliance with the ceilings, but 40–60% of samples have PAHs contents exceeding those in general industrial coatings. To investigate further potential of VOCs abatement, systematic administrative efforts should be taken. Multiple-use housing refurbishment coatings need to be considered as a distinctive type of coating in standards, and VOCs content limits should be set with a balance between film qualities. Afterward, the transparency and publication of VOCs and species contents of the domestic users are the keys to compel coating manufacturers to lower VOCs contents and adjust formulations at the national level.

Two different dispersion techniques, namely ball milling and sonication, were implemented to prepare PEEK/1.5 wt% ceria nanopowders, which were deposited using an electrostatic spraying technique on mild steel substrates (post-heat treatment of the coated sample @370 ºC for 30 min). It was observed that the ball-milled powders failed to form a coating whereas the sonicated powders resulted in a coating of ~ 95 µm thickness. To investigate the reasons for this varying behavior, the ball-milled and sonicated powders were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) to evaluate their physical and chemical properties. XRD results revealed that the sonicated powders retained a higher crystallinity (~76.46%) as compared to the ball-milled powders (~66.84%). FTIR analysis indicated uniform dispersion of ceria nanoparticles in sonicated powders. TGA showed that the sonicated powders had better thermal stability than the ball-milled powders at higher temperatures. However, an increase in the post-heat treatment time for the ball-milled powders to 90 min did result in a coating of ~ 98 µm. Hence, tribological characterization of the coatings was conducted using a ball-on-disk configuration at a load of 70 N for 10,000 cycles at 0.4 m/s, which resulted in the failure of the coatings deposited from the ball-milled powders after 2500 cycles as compared to the nonfailure of the coatings deposited from the sonicated powders even until 10,000 cycles.

Adhesion behavior is a primary consideration when applying a coating to any substrate material. Polymer coatings have been applied to glass for enhanced surface properties and protection. Several research studies have been performed on how the solvent used affects the coating properties such as glass transition temperature, relaxation behavior, and surface morphology. While multiple experiments have been conducted to investigate the solvent effect on polymer adhesion to various substrate materials, research has not yet been substantially conducted using glass as the substrate material. Here, the effect of various solvents on poly (methyl methacrylate) (PMMA) adhesion to soda lime silicate glass is investigated. PMMA is dissolved in four different solvents, acetone, butyl acetate, ethyl acetate, and toluene and coated onto 20 × 20 mm² glass substrates via spin coating. Four different methods for measuring coating thickness are explored including ellipsometry, profilometry, atomic force microscopy (AFM), and scanning electron microscopy (SEM). Adhesion is assessed qualitatively via the tape test, ASTM D3359-23. Thickness data showed conclusive proof that the spin coatings were nonuniform. Ultimately, results from the tape test show a solvent effect on PMMA adhesion to glass, establishing toluene to be the strongest out of the four for adhesion. Recommendations for experimental testing and characterization methods are presented.

Here, in order to overcome the drawbacks of carbon spheres (CS) as a single additive with high smoke emission and limited thermal stability, we constructed a highly flame retardant carbon sphere composite (CS/PCP) with C-N-P structure by chemically bonding hexachlorocyclic triphosphate (HCCP) to the surface of CS using polydopamine (PDA) as the linking medium. Moreover, the TA-Fe complex layer was uniformly wrapped around the surface of CS/PCP to obtain CS/PCP@TA-Fe composite flame retardant. The complex flame retardant additives obtained were used for the improvement of thermal insulation properties of waterborne epoxy coatings. Fire resistance tests show that the CS/PCP@TA-Fe nanomaterials enhance the thermal insulation of EP to a minimum of 171.5 °C on the backside of the samples, providing support for the high thermal insulation performance. In furnace tests, the CS/PCP@TA-Fe/EP composite coating demonstrated the highest swelling height (20.2 mm) and the largest swelling n rate (15.66), far exceeding other coatings. Besides, the CS/PCP@TA-Fe/EP composite coating obtained the largest carbon residue (28.5%) due to the metal promoting the production of carbon. Observation of the carbon surface of the CS/PCP@TA-Fe/EP composite coating after combustion revealed that the residual carbon was dense and intact compared to that of the other coatings, indicating that it could effectively inhibit the entry of heat. Therefore, the successful development of this nanocomposite fire retardant coating contributes to the further development of waterborne epoxy intumescent fire retardant coatings.

Since the main solvent of waterborne polyurethane (WPU) is water, its water resistance is poor. Additionally, the low oxygen index of WPU adhesive films limits their flame-retardant efficacy as coatings, thereby restricting their application scope. To address these limitations, this study independently modified the hydrophobicity and flame retardancy of WPU. First, a cyclophosphonitrile derivative (HCCP-6) was synthesized as a flame retardant. Flame-retardant WPU (NPWPU) was then prepared by reacting the –NH₂ group of HCCP-6 with the –NCO group of a polyurethane prepolymer, incorporating the flame-retardant properties into the WPU polymer chain via free-radical grafting. Next, hydrophobic F-SiO₂ suspensions were prepared and combined with NPWPU emulsions of varying concentrations. The mixtures were sprayed onto cotton fabrics using an airbrush to produce waterproof, flame-retardant polyurethane-coated textiles. Results demonstrated that NPWPU/F-SiO₂-coated cotton fabrics exhibited water contact angles exceeding 150°, indicating excellent hydrophobicity. These fabrics also showed increased char residue, reduced total heat release, and suppressed smoke production. This performance stems from the synergistic flame-retardant effect of nitrogen (N) and phosphorus (P), coupled with the high-temperature resistance of SiO₂, which promotes char formation, shields the material’s inner layers from thermal degradation, and enhances overall flame retardancy.

Using petroleum-based plastic materials poses many serious problems, including resource consumption and environmental pollution. Paper-based materials are good substitutes for plastic products because of their biodegradability, resource-richness, and recyclability. Paper’s poor water and oil resistance limits its wide application in food packaging. The use of water and oil repellents is an effective strategy to improve the barrier properties of paper. However, fluorine-containing oil repellents produce perfluorooctanoic acid/perfluorooctanesulfonyl compounds (PFOA/PFOS), which are hazardous to human beings and the environment, during the preparation and use of the repellents. Therefore, developing non-toxic, harmless, and biodegradable bio-based waterproof and oil-resistant coatings is the mainstream trend in the future. In this study, simple and environmentally friendly fluorine-free waterproof and oil-resistant coatings for food wrapping paper were developed by grafting oleyl alcohol onto chitosan using the ring-opening reaction of epichlorohydrin, and the reagents successfully adhered to the surface of the paper. The successful synthesis of waterproof and oil-resistant coatings was confirmed by nuclear magnetic resonance (NMR) and infrared (IR) analyses. The chitosan-based coatings (CHI-g-xOA, x = 1/8, 1/4, 1/2, 1) with different oleyl alcohol contents were prepared by the facile method. The obtained coated paper CHI-g-xOA-p (x = 1/4) has not only excellent oil resistance (Kit rating value of 11 ± 1.0/12), which meets the food-grade oil-proof requirement, but also has excellent water resistance (Cobb 60 value of 11.86 ± 1.60 g/m²). Compared with the uncoated paper, the tensile strength and water vapor transmission rate of the coated paper were significantly improved.

Marine biofouling poses a significant global challenge, inflicting extensive damage on offshore structures and vessels, leading to substantial economic losses and environmental issues. Antifouling coatings have emerged as a primary solution, as they can form a long-lasting protective layer on surfaces, offer cost-effectiveness, and have a broad application range. Early developments in antifouling coatings included biocide-containing formulations, which effectively controlled biofouling but resulted in extensive non-target mortality, presenting enduring threats to human health and marine ecosystem stability. This has underscored an urgent need for eco-friendly, high-efficiency antifouling solutions. Despite the variety of approaches studied, a comprehensive solution to marine biofouling using coatings remains elusive. Therefore, the advancement of antifouling coatings continues to be a focus of ongoing research. This review synthesizes current findings, concisely outlining the adhesion mechanisms of marine biofouling organisms and key performance parameters for evaluating antifouling coatings. It also reviews the development status of major antifouling coating types and proposes future directions for antifouling coating research.