Waterborne Paints Research Articles

Increased performance and reduced complexity

Vehicle manufacturers and their suppliers use a range of different systems for the electrostatic application of waterborne paints, many of which are over-complex and therefore too costly or do not offer the necessary flexibility. There is growing demand for improved performance and availability, together with increased flexibility and lower costs. A new high-speed rotary atomiser has been designed to meet all these requirements.

Factors influencing surface mould growth on wooden claddings exposed outdoors

Development in surface mould growth on painted/unpainted wooden claddings and acting climatic factors were investigated over a period of 3 years. Eight wood substrates, including modified, preservative-treated and untreated wood, were tested in combination with three types of paint: (1) water-borne alkyd modified acrylic paint without fungicide; (2) solvent-borne alkyd paint without fungicide; and (3) ICP (internal comparison product). One set of samples was exposed unpainted. The samples were tested according to a modified version of EN 927-3. A logistic regression model was fitted to the data. The degree of mould growth varied with exposure time, coating typology, wood substrate, temperature and relative humidity. Exposure time and coating typology contributed most to the model. After 3 years of outdoor exposure unpainted panels and panels coated with solvent-borne paint without fungicide had more mould growth than panels coated with ICP and water-borne paint without fungicide. Unpainted oil/copper–organic preservative-treated claddings had higher resistance to mould growth than other unpainted wood substrates. Coated untreated pine and coated acetylated pine were more susceptible to mould growth than other coated wooden substrates.

High performance water-borne paints with high volume solids based on bimodal latexes

The performance of water-borne paints formulated with five different high solids content acrylic (MMA/BA/MAA) latexes was investigated. These latexes had different particle size distributions (unimodal at 61 wt% and bimodal with the large mode below or above 350 nm at 65 wt% solids), different types of surfactant and in one case the carboxylic monomer was omitted. The results showed that both the particle size distribution of the latex and the paint thickening mechanism were found to be important contributors to wet paint viscosity and dry film properties. It was found that the water-borne paints formulated with the bimodal latex with particle sizes below 350 nm provided the best application properties in terms of drying time under ambient conditions, gloss (dependant on thickener type used), and mechanical properties of the paints.

Development of Recessed Pavement Markings That Incorporate Rumble Strips

In winter in Hokkaido, Japan, pavement markings are damaged from snow removal, and every spring, markings need to be reapplied. The authors propose a system of pavement markings whose recessed design prevents scraping damage from snowplows and whose incorporation of rumble strips increases driving safety. To determine the optimum design for recessed pavement markings, trial installation used 2 intervals between grooves. Driving tests found that recessed markings with long intervals generate more noise and vibration than recessed markings with short intervals, making the former more noticeable than the latter. It was found that waterborne paints are not durable enough to be used on recessed pavement markings. Spraying of thermoplastic paints were chosen instead. Furthermore, in order to improve nighttime visibility under rainy conditions, highly reflective beads were used. This paper reports on development of recessed pavement markings that incorporate rumble strips.

Characterization of a paint drying process through granulometric analysis of speckle dynamic patterns

Dynamic speckle patterns are generated by laser light scattering on surfaces that exhibit some kind of activity, due to physical or biological processes. The characterization of this process is carried out by studying the texture changes of auxiliary images: temporal history of the speckle pattern (THSP). The drying process of water borne paint is studied through a method based on mathematical morphology applied to the THSP image processing. It is based on obtaining the granulometry of these images and their characteristic granulometric spectrum. From the granulometric size distribution of each THSP image four parameters are obtained: mean length, standard deviation, asymmetry and kurtosis. These parameters are found to be suitable as texture features. The Mahalanobis distance is calculated between the texture features of the THSP images representative of the temporary stages of the drying process and the features of the final stage or pattern texture. The behavior of the distance function describes satisfactorily the drying process of the water borne paint. The results are compared with other methods. Compared with others, the granulometric method reported in this paper distinguished by its simplicity and easy implementation and can be used to characterize the evolution of any process recorded through dynamic speckles.

Use of Pavement Marking Degradation Models to Develop a Pavement Marking Management System

The Pennsylvania Department of Transportation collected periodic pavement marking retroreflectivity data on 88 roadway segments over a 1-year period from May 2007 through May 2008. The purpose of this effort was to use the data collected to develop a series of pavement marking degradation models that could be used to implement a management system. In this study, panel data models were used to estimate the service life of both waterborne and epoxy pavement markings because of the repeated retroreflectivity measurements recorded over time. It was found that pavement marking retroreflectivity decreases as the age of both epoxy and waterborne-paint pavement markings increase. White pavement markings were shown to have higher estimated service lives than yellow pavement markings. Traffic exposure was found to be negatively correlated with pavement marking retroreflectivity in the waterborne-paint analysis, but traffic exposure was not statistically significant in the epoxy pavement marking retroreflectivity model. A life cycle cost analysis showed that waterborne paints are more cost-effective than epoxy pavement markings if applied on a statewide basis.

Nanoparticles of soluble alkaline silicates as corrosion inhibitors in water based polymer dispersions

The present paper shows that soluble alkaline silicates, for example sodium silicate, act as flash rusting inhibitors, while aqueous dispersion binders were used in primer paints. Sodium silicate, potassium silicate and lithium silicate were studied for this purpose. Their inhibiting properties were described with the aid of a scanning method, determination of metal weight loss and SEM. Sodium silicate was identified as a very good flash rusting inhibitor for applications in styrene acrylate water borne paints.

Limitations of classical methods for measuring surface tension in visco-elastic liquids

The surface tension of a water/detergent mixture and a visco-elastic waterborne paint sample were measured using the classical ring method in which a thin free liquid film (lamella) is formed between the ring and the parent liquid. Lamella tension was measured during the stretching of the lamella. Measurements of water/surfactant mixtures have shown essentially classical behavior of lamella tension (independence of tension on deformation). Measurements of a waterborne paint formulation, however, have shown that after stretching of the lamella, the lamella tension decreases. The lamella tension of the paint sample increases after contraction of the lamella. Comparison of experimental results with rheological properties of the paint have shown that bulk visco-elastic properties of liquid are found in both the bulk sample and the lamella. The conclusion is that for the study of surface properties of visco-elastic liquids such as waterborne paints, the applicability of classical methods is limited. Therefore, it was necessary to develop new methods and approaches to study the properties of these materials. These methods are described in this paper.

Reducing Water-borne Paint Contamination in Electrostatic Rotary Atomizers

The electrostatic rotary atomizer has the highest paint efficiency in all kind of atomizers. The usage of an electrostatic rotary atomizer, therefore, has contributed to reduce the waste of paint and volatile organic compounds (VOCs). Concurrently, water-borne painting processes which use water-soluble paint have been introduced to reduce the amount of VOCs emissions. With the water-borne painting, the atomizer body is easily contaminated by the paint mists. The contamination has been an important problem to be solved in factories. In this report, the causes of water-borne paint contamination was considered and the experimental results of the contamination proof system were presented. The atomizer is surrounded by the repelling film that is charged and repels the incoming paint droplets which otherwise contaminate the atomizer. From the experimental results, following electrical properties are found to be important for the repelling film such as low capacitance and high insulation property to keep high surface potential. These features were also checked by the space charge measurements inside the repelling film. In addition, safety against incendiary sparking was investigated. The ground electrode of sphere, needle or blush-shape was approached to contact to the charged film. Energy of the discharge was calculated from the measured discharge current and the surface potential of the film. The discharge energy of all measured electrodes was below the minimum ignition energy of 0.24 mJ used in the painting industries. At the meantime, the results indicate that shape of the electrode is an important parameter to affect the discharge energy.

Dissolution and Protection of Aluminium Oxide in Corrosive Aqueous Media—An Ellipsometry and Reflectometry Study

Dissolution of alumina has been studied from wafers in aqueous solution by means of ellipsometry and reflectometry. It was discovered that the dissolution of aluminium oxide is promoted by ethanol amines like N,N-bis(2-hydroxyethyl)glycine and triethanolamine, and that this dissolution is retarded by sodium dodecyl sulphate (SDS) and stopped by sodium dodecyl phosphate (SDP). The protective property of SDP to alumina is in perfect agreement with earlier found results which showed that SDP efficiently hinders the oxidation of aluminium pigment flakes in alkaline aqueous solution. Ethanol amines are used to regulate the pH in waterborne paints and printing ink formulations. However, the aggressive properties of ethanol amines to alumina are a problem for these kinds of formulations. This may be attributed to the formation of water soluble complexes between ethanol amines and Al(III). To increase the shelf life of aluminium pigments in waterborne formulations in the future, the ethanol amines then need to be replaced by other, less aggressive, bases if possible.

New waterborne paints with different binders and corrosion inhibition application

Waterborne paint formulations based on three different emulsion resins were prepared with different pigment volume concentration (PVC). The effect of a prepared waterborne organic corrosion inhibitor with the best formula of each binder was studied. The role of binders on the corrosion inhibition of steel in the absence and presence of the corrosion inhibitor was studied. Physical, chemical, and mechanical properties, weight loss, corrosion resistance, and water up-take tests in the absence and presence of the corrosion inhibitor revealed that the protective properties of the three binders used at their optimum PVC against corrosion could be arranged in the following order: short oil alkyd > Urabrid AC 100 > acrylic emulsion resins. The prepared corrosion inhibitor showed excellent inhibition efficiency with the three used binders.

Electrokinetic Flotation of Process Water from Paint Booths

Abstract Electrokinetic flotation (EKF) for separation of paint solids and process water from automotive assembly paint booths was investigated in a series of laboratory-scale batch experiments. The EKF process employs a single electrode-module and a DC (direct current) power supply, but does not use any chemical agents or air supplier. The electrode-module, which consists of parallel electrode plates, was developed and used in the experiments. The influencing parameters of the EKF process for the process water treatment, including the type of paint, initial suspended paint solids (SS) concentration, and applied electric current, were investigated in the experimental program. It was found from this study that the EKF process decreased the SS concentration from 300 to 100 mg/L in 30 minutes at 55 A/m2 in the water-borne paint water, from 150 to 50 mg/L in 5 minutes at 22 A/m2 in the solvent-borne paint water, and from 550 to 100 mg/L in 5 minutes at 44 A/m2 in the mixed paint water, as well as reduced colour and chemical oxygen demand (COD). The study concluded that paint type, initial SS concentration, and electric current are the most important parameters in the EKF process governing the effectiveness of solid/water separation, treatment time, and power consumption. A comparison of SS removal between the chemical coagulation and the EKF treatments showed that SS removal by the EKF process was similar to the chemical treatment. The study concluded that the EKF is an effective technique for solid/water separation in paint booths with simultaneous COD and colour removal.

Formal rheological model of acrylic waterborne paints

A rheological model has been constructed, which has revealed, against the background of the viscous rheological properties, the role of elasticity in the orientation of pigment particles in painting by pneumatic spraying and aerosol deposition onto the surface. The model additively takes into account the elastic and viscous components of the total stress.

Exploratory Analysis of Accelerated Wear Testing to Evaluate Performance of Pavement Markings

Wear testing of pavement markings in the United States is commonly performed by AASHTO's National Transportation Product Evaluation Program. The pavement markings evaluated in this program are applied in a transverse manner along existing roadways, and a variety of objective measures are collected over a 2-year period. This paper reports the findings from an exploratory study on using the Model Mobile Load Simulator, third scale (MMLS3), to evaluate pavement marking performance along transverse test sections. Accelerated trafficking on wet and dry pavement surfaces was applied on sections of markings consisting of various waterborne paint products, marking thicknesses, and bead types and densities. Pavement marking retroreflectivity measurements were recorded at various stages of MMLS3 trafficking and compared with measurements of a test deck consisting of the same pavement markings subjected to live traffic. The findings suggest that the MMLS3 can consistently replicate the degradation pattern of the various pavement markings with regard to loss of retroreflectivity as a function of traffic passages. Performance varied among the various types of markings, with higher retroreflectivity observed for thicker markings with higher bead densities. Trafficking on wet pavement surfaces accelerated the degradation of the markings’ retroreflectivity.

Silver as fungistatic agent in paints

W pracy przedstawiono wyniki badań właściwości biobójczych dekoracyjnych farb wodorozcieńczalnych, których właściwości przeciwdrobnoustrojowe są wynikiem oddziaływania srebra. Sprawdzano skuteczność biobójczą czterech handlowych preparatów srebra, dodawanych do farby podstawowej w ilości 30ppm oraz 40ppm (masowo, w przeliczeniu na Ag). Badano powłoki świeże oraz poddawane procesowi przyspieszonego starzenia. Powłoki uzyskane z przygotowanych farb nanoszono na trzy rodzaje podłoża: szkło, płytki lignino-cementowe lub płyty kartonowo-gipsowe. Badania mikrobiologiczne prowadzono według normy PN-85/C-89080 z własnymi modyfikacjami wynikającymi ze specyfiki badanych materiałów. W badaniach stosowano grzyby pleśniowe, najczęściej wykrywane w pomieszczeniach użytkowych tj. Aspergillus niger, Cladosporium cladosporioides, Aspergillus versicolor oraz Penicillium chrysogenum. Wymienione szczepy zostały wyizolowane ze środowiska mieszkaniowego. Stwierdzono, że srebro wykazuje działanie fungistatyczne, a efekt ten zależy od rodzaju podłoża, od pH środowiska, rodzaju zastosowanego preparatu srebra oraz od gatunku organizmu zasiedlającego powłokę.

Performance of Anticorrosive Coatings Containing Tripolyphosphates in Aggressive Environments

The objective of this research was to study the efficiency of calcium tripolyphosphate and zinc tripolyphosphate as anticorrosive pigments for paints in aggressive environments. Alkyd and epoxy paints, of the solvent-borne type, containing 30% by volume (v/v) of the pigment, were formulated. The pigment volume concentration/critical pigment volume concentration (PVC/CPVC) ratio was fixed at 0.8. In a second stage, water-borne paints containing 30% v/v of both tripolyphosphates and different PVC values (20 and 25%) were also formulated. Finally, standardized accelerated (salt spray and humidity chamber exposure) and electrochemical impedance spectroscopy (EIS) tests were used to assess the protective performance of the coatings. Analysis and interpretation of the experimental data show that both, calcium and zinc tripolyphosphates, inhibit corrosion of painted steel panels exposed to aggressive environments.

Wplyw modyfikacji montmorylonitu na wlasciwosci reologiczne organicznych ukladów powlokotworczych z jego udzialem

Rheological properties of coating systems and possibility of their modifications especially by montmorillonite were characterized (Table 1) on the basis of literature data. In the own research either hydrophilic or hydrophobic modification of purified montmorillonite (MMT-S) was carried out. Hydrophylic modification with sodium salts of carboxymethyl cellulose (CMC) of various substitution degree was done while hydrophobic one carried out with amines of long hydrocarbon chain [1-hexadecylamine (A-1), ethoxylated amines containing radicals of coconut acid (A-2) or thallic one (A-3) (see Table 2)]. Spectroscopic methods, namely FT-IR (Fig. 4, 5, 8 and 9), X-ray diffraction (XRD, Fig. 1,2 and 12) and wide-angle X-ray scattering (WAXS, Fig. 13), were used for characterization of an effectiveness of MMT-S modification. In case of hydrophylic modification the largest changes were observed for the samples modified with CMC characterized with substitution degree equal 0.9 and with 50 wt. % of modifier. For hydrophobic modification with amines the part of modifier at least 1.0 CEC (CEC is a measure of cation exchange capacity) was necessary. Mixed modifier A(1+2) appeared to be the best one. Properly modified montmorillonites show improved swelling ability in aqueous and organic media (Fig. 10). It was found, on the basis of viscosity measurements and rheometric investigations, that montmorillonites could govern the rheological properties of waterborne paints and act as thickeners for solventborne paints.

Plasma Treatment of Wood–Plastic Composites to Enhance Their Adhesion Properties

In this study, the adhesion properties of adhesives and paints on wood–plastic composites (WPCs) after plasma treatment at atmospheric pressure and ambient air were investigated. Surface energy determination by means of contact angle measurements according to the Owens–Wendt approach and atomic force microscopy to detect changes in surface topography were carried out. An increase in the polar component of surface energy and an increase in surface roughness after plasma treatment were detected, indicating enhanced bond strength. To confirm these results, bond strength tests were conducted. By tensile bond strength tests, increased adhesion of waterborne, solventborne and oil-based paints on plasma treated surfaces was found. Furthermore, by shear bond strength tests, an increase in bond strength of plasma treated WPCs bonded with poly(vinyl acetate) and polyurethane adhesives was ascertained.

Hydrated alumina surface treatment on a titanium dioxide pigment: Changes at acidic and basic pH

Amphoteric, inorganic particles used as pigments and extenders in dried coatings are not completely inert, particularly when exposed to acidity similar to atmospheric pollution, or when in a water-borne paint suspension at alkaline pH. Changes to these materials may harm the integrity of the dried coating and thus its performance during weathering or affect the colloidal stability during storage within liquid paint. The effect on aqueous titanium dioxide pigment suspensions was examined under various pH conditions. A substantial amount of aluminum was dissolved, but little silicon or titanium. Dissolution occurred at both acid and alkali pH leaving a different balance of hydrated alumina phases and overall surface composition. Changes in particle surface were apparent in topography, colloidal properties and by thermogravimetry. Such changes show that other, more complicated, changes may be possible, particularly in an aqueous paint medium where there are many other ingredients in solution or suspension.

Water uptake of water-borne paint resin films as studied by impedance spectroscopy and gravimetry

Impedance spectroscopy and gravimetry were employed to characterize alkyd-acrylate and styrene-acrylate water-borne resin film properties during wetting-through (i.e. during water uptake). The results were obtained by (i) measuring the weight of the resin films during soaking in solution and by (ii) measuring impedance of the film between two electrolyte contacts in a two-compartment electrochemical cell. Both methods characterize the effect of dilute solution upon film properties: gravimetry yields a direct measure of water content; impedance spectroscopy enables us to characterize dielectric and ion transport properties of the film. By evaluating the measured data, we were able to distinguish the following processes taking place when a dry resin film got in contact with a solution: (i) penetration of the solution into macro-pores that form transfer paths of the dry resin; (ii) structural changes of the polymer molecules due to swelling; (iii) transport of charge holding species within the polymer. The polymer properties, namely, swelling ability and conductivity were studied and were found to be different for two types of water-borne resins. The physically drying styrene-acrylate resin is more porous and is more apt to swell than the oxidatively drying alkyd-acrylate resin.