Dry Paint Film Research Articles

Design of dual-functional Mg/Al layered double hydroxide for smart protective coatings

Although corrosion inhibitors are often added to protective coatings to hinder the corrosion at defect sites, the normal inhibiting pigments are prone to uncontrollable leaching of the active component, leading to fast exhaustion of anti-corrosion properties. Moreover, the protective coatings hide the corrosion, making it difficult to detect the initial degradation processes on the steel. Therefore, it is desirable to develop “self-healing” and “corrosion-sensing” smart solutions for long-term protection and early detection of the onset of corrosion. Herein, we demonstrate the intercalation of corrosion inhibitors and corrosion sensors into layered double hydroxides via an anionic-exchange process and surface modifications with rhodamine B derivative RB2. Electrochemical measurements showed that adding 8 wt% Mg/Al LDH-MoO42−-RB2 pigment in dry paint film provides the epoxy coating with self-healing ability in the event of microcracks for up to 120 h of exposure in salt spray chamber. In addition, pinkish spots were observed near the scribed line at 120 h of salt spray exposure, demonstrating that the added corrosion sensor provided early detection of corrosion upon exposure to Fe3+ ions. The results of this study will aid in reducing the risk of corrosion through self-healing and allow for the detection of corrosion for maintenance purposes, especially in the oil and gas industry.

Efficacy of zinc and copper oxide nanoparticles as heat and corrosion-resistant pigments in paint formulations

This study focuses on the synthesis of zinc and copper oxide nanoparticles using green methods by plant extracts. The resulting metal oxides were analyzed using FT-IR spectroscopy, TGA, TEM, zeta potential and assessed for their efficacy as pigments based on properties such as Hydrogen Ion Concentration, Oil absorption, Moisture Content, Fineness of grinding, Bleeding, and loss on ignition. The results confirmed that the prepared ZnO and CuO nanoparticles exhibited the formation of nanoparticles in the range of 10–40 nm with potential as pigments. Two paint formulations incorporating these nanoparticles and silicon resins as binders were tested for physico-mechanical attributes, chemical resistance, heat resistance, and corrosion resistance of the dry paint films. The study found that the films containing the prepared oxides demonstrated excellent performance, with no damage or color alteration observed after exposure to temperatures up to 500 °C. Moreover, the paint films containing ZnO nanoparticles showed superior efficiency after a 500 h salt spray test compared to those with CuO nanoparticles. These findings suggest that the synthesized mixed oxide nanoparticles are promising candidates for heat-resistant pigment applications.

Development of methodology for the visual identification of Tributyltin (TBT) in antifouling paint matrices.

Organotin compounds (OTC), mainly tributyltin (TBT), have been used since the 1970s as biocides in the composition of antifouling paints. Due to its physical-chemical characteristics, TBT has high toxicity to the marine environment affecting non-target organisms. The present study aims to develop a method of direct visual identification of TBT in antifouling paints using the cyclopalladate complex, 4- (2-thiazolylazo) resorcinol (TAR-Pd), synthesized in our laboratory. Tests were performed in blank and in the paint matrix with the following OTC: TBT-O; TBT-Cl; TPT-Cl; DBT-Cl (tributyltin oxide, tributyltin chloride, triphenyltin chloride, dibutyltin chloride), in addition to the SnCl4 and SnCl2 compounds (tin IV chloride and tin II chloride), all at a concentration of approximately 20g/ kg of dry paint). The test was performed by applying paint samples to test bodies and scraping a few tens of milligrams of the dry paint film. The scraped paint samples were submitted to the test, showing a different staining reaction for the TBT-Cl and SnCl4 samples concerning blank and other samples (TBT-O, TPT, DBT-Cl, and SnCl2). Solution tests were performed to characterize reaction products by spectroscopy in the visible band. The method developed has potential for application in real samples, being selective for TBT-Cl and SnCl4 in an acid medium, obtaining a limit of detection, in the range of 1-10mg/kg dry paint.

Graphene thermally modified with polyvinyl alcohol applied as conductive water-based paints based on polyurethane

This paper presents the fabrication of thermally reduced graphene modified with polyvinyl alcohol (PVA), which can be used as a conductive water-based paint based on polyurethane (PU). Graphite oxide (GO) was oxidised from graphite by the Hummer method, and then graphene was formed by the thermal-reducing GO method. The graphene was modified by dispersing it into a PVA solution with various concentrations and mass ratios to optimise the modification process. The graphene modified with PVA could be easily dispersed in water. Water-borne PU film-forming polymer was prepared by polymerisation reaction between isophorone diisocyanate with poly(tetramethylene glycol) and dimethylolpropionic acid. The carboxylate functional groups on the surface of the polymer particles make the polymer particles dispersed well and stable in water, so this polymerisation process does not use any surfactants. The characterisation methods included field emission scanning electron microscope with energy-dispersive X-ray spectroscopy (FESEM-EDX), specific surface area measurement, Raman microspectroscopy, resistance measurement... The graphene-based conductive paint has good adhesion, conductivity of the dry paint film was from 0.1-4 mS/cm with graphene content in the dry paint film was about 5-10 wt%.

Fabrication of low emissivity paint for thermal/NIR radiation insulation for domestic applications

Recently, low-emissivity paint has gained more importance than commercial paints. Low emissivity (Low-E) Paint also termed as a coating for radiation control, in which the emissivity of radiations of longer waves are reduced dramatically (i.e., the emissivity of commercially available paint is 0.9) by imparting low emissivity particles in the base paint but not suitable to reduce near-infrared radiation. Commercially available paints as of today have minimum of 0.7 emissivity and it does not give any significant energy saving. The low emissivity property of paint makes it particularly suitable for reducing the radiative heat exchange in many domestic applications i.e., home electronics, building construction components, roof surfaces, heat storage tanks, and pipes, etc in result, low power required to heat or cool the building in respective whether conditions. In this work, different samples of white paint were prepared in the lab by using a low shear mixer (mechanical stirrer) under very controlled conditions and studied the results of dry paint films to reduce the thermal emissivity then commercially available paint. Then we investigate the drying time of the wet paint films and analyze thermal heat into visible light through thermal imaging camera, Crosshatch, and IR transmission. We also studied the emissivity through ET-100 and aging stability through a weather-o-meter instrument, which investigated that emissivity value achieved in the range of 0.4–0.6 than commercial paints. The results showed that paint exhibits an acceptable aesthetic emissivity value of ∼0.60. It was calculated theoretically that by the use of this novel Low-E paint, annually about 20%–25% less energy will be consumed in building for cooling or heating.

Simultaneous Spatiotemporal Measurement of Structural Evolution in Dynamic Complex Media.

When the properties of soft materials evolve in time, the simultaneous measurement of different characteristics is critical. Here, we demonstrate an experimental system that permits monitoring both the spatial and temporal evolution of the optical and mechanical properties. An integrated fiber-optic-based system allows determining the mechanical vibrations of structural elements over 5 orders of magnitude and over a broad frequency range. At the same time, the optical properties can be obtained within seconds from high-resolution measurements of the path-length distribution of reflected light. With proper cyclical scanning, the temporal evolution of the mesoscopic light scattering properties can be obtained in a depth-resolved manner. The performance of this integrated measurement is validated in the particular case of drying paint films. For these typical nonstationary media, we show how our approach provides unique access to the spatiotemporal material properties and how this information permits identifying the specific stages of structural evolution.

Green antifungal waterborne coating based on essential oil microcapsules

There is a great concern about the indoor microbial colonization especially in places that should have high standards of environmental hygiene. Besides, due it shortened the useful life of the coating by discoloration and degradation. Currently this is a problem that must be solved in an innovative and eco-friendly way. In this sense, the aim of the work was to develop a green waterborne paint formulated with microcapsules containing essentials oil as biocide agent. This novel hygienic coating would be applied as to protect indoor surfaces from fungi. The microcapsules were synthesized by interfacial polymerization. Melamine-formaldehyde (MF) resin was used for the microcapsule shell wall, and Lavandin and Tea Tree essential oils (EOs) as core materials. The synthesized microcapsules were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and particle size analysis. Preparation of acrylic waterborne paint was performed and the microcapsules MF-EOs were dispersed into the original paint just before application on commercial gypsum boards. The stability of the MF-EOs in the paint was successfully achieved. Two control paints were used, one containing EOs in free form and other without biocide.The effectiveness of the microcapsules into paint film against spore suspension of Aspergillus fumigatus was evaluated by seeding the fungus on the painted surface. The fungal growth was evaluated according to ASTM D5590 standard specification. The score obtained from MF-Lavandin paint indicates just a trace growth onto the painted surface (<10 %). On the control and MF-Tea tree paints the growth was 70 %. The MF-Lavandin showed a high inhibition activity against fungal in the dry paint film compared with the one containing free form EOs paint.

The importance of underpaint corrosion caused by damage to paint on steel structures

The impact of varying the dry paint film thickness (DFT) on the underpaint corrosion of steel plates obtained from the floor of an offshore oil platform is evaluated. The specimens were all prepared using the same material and paint scheme, and the DFT and exposure conditions in a salt spray chamber were varied and compared with the results obtained in a real situation. The results indicated that corrosion initiated at sites where the paint was damaged, may be more important than corrosion through the undamaged paint due to permeation, even in cases where the DFT is thin. In specimens whose substrates were previously damaged, there were pathological manifestations of osmotic blistering. The underpaint corrosion that occurred after the paint was damaged in the field occurred at an intensity like that observed for the tested specimens.

Colour variation in drying paint films

Color variations due to changes in paint film thickness and pigment content were studied experimentally. Three paints with differing concentration (0.5%, 2% and 4% by weight) of spherical blue pigments were applied with varying film thickness (310, 490, 730 μm) on stainless-steel substrates and dried in an oven while the paint surfaces were photographed. Weight loss due to solvent evaporation from the paint was recorded. The color of the dried paint films was measured. Surface tension driven convection was observed in drying paint films, which caused movement of pigment particles. An analytical model was used to predict solvent concentration gradients in the paint films and calculate Marangoni numbers, which determined the velocity of fluid motion. All motion stopped when the Marangoni number became small. Pigment particles tended to cluster around the edges of convection cells and produce changes in color, especially when the paint films were thin and the pigment fraction low. Increasing either the amount of pigment or the paint thickness made the paint color lighter, as a larger number of pigment particles increases reflection of light. Paints with high pigment concentration are less likely to see changes in color.

Production of Antifouling Paints’ using Environmentally Safe Algal Extracts on Laboratory Scale

Fouling is a result of the accumulation of bacterial growth, algae and sessile invertebrates on both natural and manmade submerged surface. To combat fouling ships must constantly undergo cleaning up and maintenance processes. This work aimed to evaluate new biocide antifouling paints produced from marine algae, and study their suppressive effect on slime film forming bacteria. In addition, the effect of the leached components from these wood coated surfaces containing algae on the characteristics of the contact seawater medium was investigated compared with two commercial marine paints. To evaluate the suppressive effect of algae containing coatings, extraction of the new biocide antifouling paints were done by mixing different ingredients % of binder, pigment, filler, stabilizer and solvent. The obtained paints were durable, long lasting with no cracking formed before their incorporation with algae. The paint formulations were applied to wood panels and immersed in sterile glass beakers filled with seawater medium collected from the Eastern Harbour, Alexandria, Egypt. The physicochemical parameters (temperature, salinity, pH, dissolved oxygen and nutrient salts) of seawater samples around the tested panels’ were measured after four weeks of immersion and the microbiological examination for the panels were measured after two and four weeks of immersion.Using of algae in the dry paint film leads to highest suppressive effect (%). The tested Ulva fasciata, Corallina mediterraneaand Codium Tomentosum were having the highest suppressive effect 100, 99.6 and 99.5%, respectively. These results matched with the characterization by gas chromatography-mass spectrophotometer (GC-MS) and Fourier transform infrared spectroscopy (FTIR).

Preparation and Characterization of an Emulsion Paint Based on Arghel Extract as an Eco-Friendly Corrosion Inhibitor

Corrosion control of metals is of technical, economical, environmental, and aesthetical importance. The use of inhibitors is one of the best options of protecting metals and alloys against corrosion globally. The environmental toxicity of organic corrosion inhibitors has prompted the search for green corrosion inhibitors which do not contain heavy metals or other toxic compounds. In addition to being environmentally friendly, plant products are inexpensive, readily available and renewable. With the growth of the green movement, it is important to prepare environmentally friendly anticorrosive paints to save lot of money, which are lost each year because of corrosion. This study utilized optical measurements, electrochemical impedance spectroscopy (EIS) analysis, scanning electron microscope (SEM) analysis, immersion test in artificial sea water and morphology observations of Arghel extract (AE) as Eco-friendly corrosion inhibitor incorporated in (styrene-acrylic) emulsion paint. In addition Physical, Chemical and Mechanical Properties of dry paint films of the paint test has been done in absence and presence of the corrosion inhibitor. We found that (styrene-acrylic) emulsion paint with 75ppm AE (SP2) has the best performance in protecting mild steel from corrosion.

Preparation and spectroscopic studies of some nano copper and nickel Schiff base complexes and their applications as colouring pigments in protective paints industry.

New copper (II), nickel (II) Schiff base complexes derived from 3,3 Dimethoxy anizidine and selected aldehydes, namely 2,4 dihydroxybenzaldehyde with the metal salts have been synthesized using a simple technique of microwave method (Green chemistry). The physical properties of prepared ligand and its metal complexes were recorded. The ligand and complexes were characterized using elemental analysis, NMR, infrared and also their geometrical structure were investigated using spectral UV–Vis reflectance, magnetic susceptibility, electron spin resonance (ESR), thermal gravimetric analysis (TGA) and scan electron microscope (SEM). The performance tests (oil absorption, fineness of grind, moisture content, pH and bleeding test in different solvents) of the solid metal complexes were explored to ensure that the complexes can be used as a pigments in the field of anti-corrosive paints without any compatibility problems in the paint’s vehicle. The anti-corrosive paints were formulated based on the prepared metal complexs as a pigments and the Physical, mechanical, color properties and corrosion resistance of dry paint films were also examined. The obtained results revealed that the prepared metal complex pigments showed excellent mechanical, corrosion resistance with color stability and don’t effect or react with the other components in the anti-corrosive paint formula.

Bubble Clustering in Drying Paint Films

Paint films with uniform thicknesses (∼1 mm) were applied on glass substrates using a model paint consisting of a resin dissolved in butanol. Small air bubbles were introduced into the liquid, and test samples were cured in a natural convection oven. Bubbles in paint grew larger as the evaporating solvent diffused into them. Photographs of the liquid film surfaces were taken during drying, and the distance between bubbles was measured. Bubbles were observed to move toward each other and form clusters. When a vertical surface was introduced into the liquid film, bubbles moved toward the surface if the liquid–solid contact angle θ 90°. A floating bubble or hydrophilic surface creates an upward curving liquid meniscus near itself so that neighboring bubbles experience buoyancy forces that drive them up the rising liquid surface. A hydrophobic surface creates a downward-curving meniscus, so that bubbles move away from it. Bubble motion was modeled using an analysis of the shape of ...

Performance Evaluation of Aro-Ndizuogu Local Clay in Alkyd Paint Production

The potentials of Aro-Ndizuogu clay as an extender in gloss paint have been investigated. The physical properties of the local clay investigated: refractive index (1.54), pH (7.10), oil absorption (32g/100g clay), and specific gravity (2.13) compared favourably with that of conventional extenders. Gloss paints were prepared using the local clay (as an extender), xylene as solvent, and alkyd resin as binder. Paint samples prepared using TiO2 pigment was used for comparison. Results obtained from the analysis of the paint samples showed that TiO2 formulated alkyd paint samples exhibited the highest specific gravity (1.42) while the alkyd paint containing 50 % local clay, the least (1.30). While TiO2 formulated paint samples did not show any settling tendency, paint samples containing 50 and 60 % local clay had poor settling tendencies. The resistance of dry paint films was generally good in 20 % Na2CO3, distilled water, and 20 % NaCl. However, all the prepared paint samples failed NH3, and H2SO4 resistance tests. The present study has shown that Aro-Ndizuogu clay exhibited similar performance properties in the prepared alkyd paint samples like TiO2 prepared paint, and should find utilization in the surface coatings industry.

Performance Evaluation of Aro-Ndizuogu Local Clay in Alkyd Paint Production

The potentials of Aro-Ndizuogu clay as an extender in gloss paint have been investigated. The physical properties of the local clay investigated: refractive index (1.54), pH (7.10), oil absorption (32g/100g clay), and specific gravity (2.13) compared favourably with that of conventional extenders. Gloss paints were prepared using the local clay (as an extender), xylene as solvent, and alkyd resin as binder. Paint samples prepared using TiO2 pigment was used for comparison. Results obtained from the analysis of the paint samples showed that TiO2 formulated alkyd paint samples exhibited the highest specific gravity (1.42) while the alkyd paint containing 50 % local clay, the least (1.30). While TiO2 formulated paint samples did not show any settling tendency, paint samples containing 50 and 60 % local clay had poor settling tendencies. The resistance of dry paint films was generally good in 20 % Na2CO3, distilled water, and 20 % NaCl. However, all the prepared paint samples failed NH3, and H2SO4 resistance tests. The present study has shown that Aro-Ndizuogu clay exhibited similar performance properties in the prepared alkyd paint samples like TiO2 prepared paint, and should find utilization in the surface coatings industry.

Microwave synthesis and spectroscopic studies of some complex compounds as pigments and their applications in paints

Metal complex pigments have been widely used for various applications such as pigments in coatings. This work presents the use of microwave technique (Green chemistry) for the synthesis of new copper(II), nickel(II), iron(III), and chromium(III) Schiff base complexes derived from metal salts and Schiff base ligand. Also, the microwave technique was used in the synthesis of Schiff base ligand which is derived from selected amine, namely methoxy-tolidine, and selected aldehyde, namely 2-hydroxynaphthaldehyde. The prepared ligand and metal complex pigments were characterized by elemental analysis, NMR, spectral UV–Vis, infrared, and thermal gravimetric analysis. The physical and mechanical properties and corrosion resistance of dry paint films were also examined. The obtained results revealed that the prepared metal complex pigments showed excellent mechanical and corrosion resistance.

Bubble growth and movement in drying paint films

Paint films with uniform thickness were applied on stainless steel and glass substrates using a model paint consisting of a resin dissolved in butanol. Tests were also done using glycerin–butanol solutions that were as viscous as paint but did not harden after drying. Small air bubbles were introduced into the liquid and test samples cured in a natural convection oven at temperatures varying from of 100–140°C. Relatively thick (1mm) paint layers were used in experiments to allow large bubbles to grow that were easy to observe. Photographs of the liquid film surfaces were taken during drying and weight loss was measured. Cellular structures appeared in drying paint films, induced by surface tension gradients. Small bubbles were transported from the centers to the edges of the cells formed in the liquid layer. Bubbles grew larger as the evaporating solvent diffused into them and were drawn towards each other, forming clusters. Analytical solutions of the mass-diffusion equation were used to model solvent evaporation from the paint film surface, calculate the magnitude of concentration gradients, and estimate bubble growth rates.

Self-cleaning acrylic water-based white paint modified with different types of TiO2 nanoparticles

Purpose – This paper aims to study the Improvements in self-cleaning property of the white acrylic water-based paint by addition of different percentages of three commercially available titanium dioxide (TiO2) nanoparticles as additives. Then, due to the risk of destruction of polymeric materials in the presence of nanoparticles, degradation of dry paint film samples was investigated for 15 days using two important chalking and yellowing factors. Finally, the TiO2-modified paint sample with the best performance and optimum percentage of TiO2 nanoparticles that produced desired self-cleaning and dry film properties was introduced. Design/methodology/approach – Self-cleaning and dry film properties of white acrylic water-based paint were investigated by addition of three various types of commercial available TiO2 nanoparticles (SSP-25, STA-100 and KA-100). X-ray diffraction, transmission electron microscopy and Brunauer–Emmett–Teller were used for characterization of TiO2 samples. Colorimetric tests in decolourization of C.I. Basic Red 46 (BR46) were used for determination of self-cleaning properties of TiO2-modified paints in comparison with unmodified paint sample. Also, paints defects such as chalking and yellowing were tested along two weeks. Findings – The results indicated that, in all types of TiO2 nanoparticles, by increasing the amount of TiO2 in modified paint, self-cleaning property of the samples was enhanced. The paint containing SSP-25 indicated better self-cleaning properties than others due to its larger surface area. However, its usage above 3.5 weight per cent caused yellowing and chalking defects in dried paint film. Practical implications – In this research, TiO2-modified paint sample with the best performance in both self-cleaning and mechanical properties was selected among the nine sets of prepared paint samples. All the materials used in this research such as acrylic resin and three types of TiO2 nanoparticles are of industrial grade. Therefore, the introduced TiO2-modified paint sample has the potential for the commercial production as a building exterior paint. Originality/value – In the present study, an attempt at introducing a self-cleaning paint sample with acceptable mechanical properties using three types of commercially available TiO2 nanoparticles as additives and industrial grade of acrylic resin which is the most commonly used water-based resin in building paints, as binder. As far as it was searched in the literatures, the parallel study of the self-cleaning and mechanical properties of paints has not been reported as noteworthy. Self-cleaning property of the acrylic water-based paint samples was investigated by adding three types of the commercially available TiO2 nanoparticles. Also considering the possible detrimental effects of TiO2 nanoparticles on polymeric materials and consequently on physical properties of the paint, chalking and yellowing factors in dried paint samples were evaluated.

Geometry of a paint film: Basics revisited

Abstract “Pigment/binder geometry”: this is the title of a chapter in “Paint, flow and pigment dispersion”, the well known textbook [1] by Temple C. Patton that contributed to the coatings education of generations of paint chemists. The author had designed a graphical representation – the first one of this kind – of the volume repartition of the main components of a dry paint film as a function of the Pigment Volume Concentration, or PVC, of the paint. It was the source of inspiration for this article. His approach was however focused upon systems where the binder phase was an oil and would need to be refined and developed further when latex polymers are used instead. This is the object of the communication that follows. It is also the opportunity to re-visit a number of basic concepts.

Orange peel formation due to surface tension-driven flows within drying paint films

Paint films with uniform thicknesses ranging from 150 to 820 μm were applied on stainless steel substrates using a model paint consisting of a resin dissolved in butanol and the test samples were cured in a natural convection oven at a temperature of 140°C. Photographs of the paint surface were taken during drying, and the weight loss was measured. Cellular structures appeared on the paint surface, induced by surface tension-driven flows due to solvent concentration variations. For thin films (<500 µm), the patterns disappeared in a few minutes and the dried paint surface was smooth, while for thicker paint films, wave-like structures remained on the hardened paint layer, creating an uneven surface. An analytical solution of the mass-diffusion equation was used to model solvent evaporation from the paint film and to calculate the concentration gradient and surface tension variations in the paint films. In thin films, all the solvent was depleted, and surface tension gradients disappeared before curing was complete, allowing the surface to become smooth. In thicker films, concentration gradients that drove cellular flows persisted until the paint dried, leaving orange peel on the surface.