Electric conductivity measurements in water dispersion paints for mechanistic studies of reflection properties formation during surface painting and paint film drying

Electric conductivity measurements of water dispersion paints were carried out in order to understand the mechanism of film formation and drying and the formation of painted surface reflection properties. The classical model of electric conductivity in viscous media based on a comparison of the Coulomb and Stokes formulas was used to determine the effective mechanism of the paint properties. This model was verified by measurements in the paint bulk. The classical concept of the electric conductivity of viscous liquids was found to be applicable to the conductivity analysis of the studied water dispersion paint specimens. The electric conductivity of the studied paints was found to be determined by the existing admixtures being soluble in water and/or dispersion organic particles. The formulated method for dynamic conductivity measurements of paint film thickness assumed a constant temperature and viscosity. Strong electrostatic phenomena were detected at the initial stage of paint aerosol deposition, while a compact film has not been formed yet. The film conductivity measuring experiments found that the film drying process consists of two stages. At the first stage, conductivity is sharply decreasing and the paint film reflectivity is sharply increasing. At the second stage, evaporation is delayed. It is limited by the diffusion transfer of volatile components from the film bulk and from the paint dispersion particles. Here, a slow growth of the reflectivity and a decelerating decrease in the conductivity is observed. A qualitative mathematical dynamic model was developed for the paint film reflectivity due to the orientation of pigment particles, and the calculations showed that the first stage of drying is the most important for the orientation.     

Fate of a coalescing aid after latex paint application

Water-based coatings require coalescing aids to achieve properties equivalent to solvent-borne paints. A common coalescing aid in latex paints is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TMPD-MIB). The relatively large quantity of TMPD-MIB used in latex paints has raised concerns regarding its emissions to both indoor and outdoor atmospheres. In this study, a one-dimensional dual (paint and material) layer diffusion model was developed to estimate emissions of TMPD-MIB from two latex paints applied to gypsum board. The paints contained different pigment volume concentrations (PVC) and different amounts of TMPD-MIB. Different modeling approaches were used depending on the PVC of the paint. The proposed model for paint drying and TMPD-MIB emissions was tested with data from previous chamber experiments. Experimental data were first used for purposes of parameter estimation, and the model was then compared against an independent experimental dataset. The diffusion coefficient of the paint layer was adjusted as a function of the water content remaining in the wet paint film. The effective diffusion coefficient of TMPD-MIB in the paint layer was found to be dependent on the PVC and water content of the paint.     

Grafting. IV. Graft tercopolymers as antifouling resin

A graft tercopolymer CLR-g-(MMA–TBTMA) based on chlorinated rubber as the backbone and binary copolymer of methyl methacrylate and tributyltin methacrylate as grafted chains has been synthesized. This graft copolymer has been used for the formulation of controlled-release antifouling paints, and leaching rate behavior of toxin from such paints has been studied. The data have been compared with those obtained using controlled-release antifouling paint based on linear chain copolymer of methyl methacrylate and tributyltin methacrylate. The paint based on grafted copolymer is characterized by having a lower leaching rate and reduced time for attainment of steady-state leaching. Raft exposure studies indicate longer antifouling life compared to that of linear chain copolymer-based paint both having the same dry paint film thickness.     

Absorption and diffusion measurements of water in acrylic paint films by single-sided NMR

Artists’ acrylic paint surfaces can accumulate surface grime. Aqueous surface cleaning of these paints can be particularly problematic because they swell upon exposure to water and because of the presence of water extractable additives. Research to determine the parameters of water penetration and swelling as well as the role of the water soluble additives in these phenomena is important in order to understand the leaching mechanism and possibly describe the best conditions for removal of water soluble grime. In this work, the penetration and molecular dynamics of water with different salt concentrations in films of artists’ waterborne acrylic paint were studied for the first time in situ using noninvasive single-sided nuclear magnetic resonance (NMR). This novel approach demonstrated that the absorption of water in the acrylic film is independent of the salt concentration, whereas the absorption of water in water-washed acrylic paints, after the water soluble components have been removed, is not only 15% less than unwashed paint films but it also decreases with increasing salt concentration. In addition, the self-diffusion coefficients of water within the acrylic polymeric network were determined and analyzed. The diffusion coefficients of water depend only slightly on the salt concentration and are only marginally influenced by the amount of incorporated surfactants. Thus the diffusion rate of water within the acrylic polymer film appears to be almost independent of the salt concentration or the surfactant content.     

舰船防污涂料的历史、现状及未来

舰船防污涂料的发展分为三个阶段,即传统的常规防污漆、现代有机锡共聚物自抛光防污漆和无锡自抛光及无毒防污涂料。我国目前处于第二阶段的初期水平。作者通过回顾历史、分析现状,对今后舰船防污涂料的发展作了展望。     

A study of the leaching of cuprous oxide from vinyl antifouling paints

The sea water leaching rate of cuprous oxide used as a toxicant in vinyl antifouling paints was studied in this work. Three paints were formulated: one of the soluble matrix type and the other two with an insoluble matrix. Two different toxicant levels were employed, and the paints were tested on a raft in Mar del Plata's Harbour, Argentina.

Cuprous oxide lixiviation was studied over 15 months by determining weight changes and by means of microscopical examination (optical and SEM) of specially prepared cross-sections. A complementary analysis by EDAX electron dispersive analysis of the leached matrix and of the paint film/sea water interface was made.

It was determined that the leaching line is parallel to the film surface. Experimental values demonstrated the different dissolution rates of paints with soluble and insoluble matrices and the lineal relationship existing between leaching rate and immersion time. Marson's formula for the determination of leaching rate at the laboratory (using the sodium glycinate method) was correlated with values obtained in sea water immersion, introducing a constant for each type of paint.     

Seawater-soluble pigments and their potential use in self-polishing antifouling paints: simulation-based screening tool

This work concerns the on-going development of efficient and environmentally friendly antifouling paints for biofouling control on large ocean-going ships. It is illustrated how a detailed mathematical model for a self-polishing antifouling paint exposed to seawater can be used as a product engineering tool to obtain a quick estimate of the paint behaviour that a given seawater-soluble pigment will provide. In the present context, “pigment” refers to relevant particulate solids of organic-, inorganic-, or biological nature. Simulations performed at 15 and 30 °C suggest that pigment solubility and seawater diffusivity of dissolved pigment species have a significant influence on the polishing and leaching behaviour of a typical self-polishing paint system. The pigment size distribution, on the other hand, only has a minor influence on the paint–seawater interaction. Simulations also indicate that only compounds which are effective against biofouling at very low seawater concentrations are useful as active antifouling paint ingredients. The need for model verification and exploration of practical issues, subsequent a given pigment has been found of interest, is discussed. The model approach is of relevance in the search for novel antifouling paints and for the development of accelerated test methods.     

Investigating Effect of Conventional and Nano Zinc Pigments on Air-Drying Property of Palm-Stearin-Based Alkyd Resin Paints

Air-drying white paint based on palm stearin alkyd resin was prepared with conventional and nano-ZnO and ZnS pigments. The effects of used pigments on air-drying time and some physical-mechanical characteristics of the paint were investigated by comparing them with conventional counterparts. It was found that ZnS has little effect on the drying time of alkyd paints, and the time of paint drying does not depend very much on the volume concentration of this pigment. ZnO pigments had outstanding effects on drying time and physical–mechanical properties of the air-drying paints, but the best result was observed for paints containing nano–ZnO. Zinc-containing pigment systems, if composed of the nano-type, provide excellent results.     

Eco-friendly zero VOC anticorrosive paints for steel protection

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. High molecular weight organic corrosion inhibitor (safe adduct), barrier anticorrosive pigment (safe) and convertible anticorrosive pigment (toxic) are protective elements in paint formulations. Emulsification of the prepared adduct was the way to be applicable in water-borne paints, using mixture of emulsifiers. Surface tension measurements using ring method technique and thermal stability test could characterize the prepared emulsion systems. It was interesting to study the performance of the protective elements in water paint formulations based on short oil water thinned alkyd. Physical and mechanical properties of dry paint films, corrosion tests of the coated steel, water up-take% of the prepared paints, weight loss of steel under paint films after immersion in artificial sea water and corrosion inhibition efficiency of the protective elements were determined. Comparative studies of the protective elements in water-borne paints have been done according to performance, economic feasibility and environmental safety. It was found that zinc chromate as carcinogenic anticorrosive pigment could be replaced by 0.09% of the prepared water-borne corrosion inhibitor (MTDT adduct), 20% micaceous iron oxide (MIO) or their blend. Superior corrosion inhibition efficiency of steel was obtained in case of using MTDT/MIO blend. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Contact angle measurements to determine the rate of surface oxidation of artists’ alkyd paints during accelerated photo-ageing

The rate of surface photo-oxidation and changes in polarity of the surfaces of artists’ alkyd paint films were studied by a rapid and novel approach using sessile drop contact angle measurements. The contact angles of distilled water and diiodomethane drops on the film surfaces were measured over a period of 25–2000 h of artificial ageing at 40 °C under an indoor light filtered Xenon light source. Chemical changes on the surfaces of the films were also followed using Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Titanium white artists’ paint samples from three different manufacturers were investigated: Winsor & Newton, Ferrario and Da Vinci Paint Co. As the films aged, there was a decrease in the contact angle and an increase in the polar component of the free surface energy of the paint film surfaces indicating the formation of photo-oxidation products. Such changes correspond well to the chemistry of oil paints, and suggested chemistry of long-alkyd paints, because of their relatively high weight percent of fatty acids.     

Calcium tripolyphosphate: An anticorrosive pigment for paint

The objective of this work was to evaluate the performance of calcium tripolyphosphate in anticorrosive paints. Its anticorrosive properties were studied in pigment suspensions and in solventborne paints with 10% and 30% of the pigment by volume and a pigment volume concentration/critical pigment volume concentration (PVC/CPVC) equal to 0.8. The behavior of paints formulated with epoxy and alkyd resins was assessed by accelerated (salt spray cabinet and humidity chamber) and electrochemical tests (corrosion potential, ionic resistance, and polarization resistance). Calcium tripolyphosphate was proven to inhibit steel corrosion when incorporated in a paint film. Good protection was achieved employing only 10% by volume of the pigment, instead of 30%, as was suggested in the case of phosphates. The anticorrosion protection afforded by alkyd paints was impaired when the pigment content was increased. Epoxy paints seemed to be less sensitive to the pigment content. Centro de Investigación y Desarrollo en Tecnología de Pinturas (CIC-CONICET), Calle 52 e/121 y 122. (1900) La Plata. Argentina. Fax: 54.221.427. 1537. email: cidepint@ba.net     

The use of calcined clay as part replacement of titanium dioxide in latex paint formulations

Titanium dioxide, TiO_2, being a prime pigment, has been used extensively in the paint industry. The growing demand and the increasing cost of TiO₂ has driven the attention of paint technologists to search for other alternatives. There has been continuous effort to replace part of the TiO₂ with a fine particle size extenders in paint formulations. A detailed study has been undertaken to replace TiO₂ pigment by various percentages of calcined clays in two latex paint formulations. Properties such as thixotropy, hiding power, light fastness, film brightness, scrub resistance, and weather resistance have been determined to establish the optimum use of calcined clays in the paint formulation. Thixotropy, one of the important properties of latex paints, has been studied with the help of thixotropic loop area method. The viscosity data has also been analyzed by Casson's equation. It has been found that the calcined clays can replace up to 20% TiO₂ in paint formulations without having any adverse effect on their properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1029–1036, 2000     

Simulations and experimental investigation of paint film leveling

The surface structure of a paint film is the result of the interplay of a variety of physical influences, e.g., the superposition of droplets during spray application, the surface tension-driven leveling, and the viscosity increase in the leveling phase. A numerical simulation program is presented that incorporates all the relevant mechanisms of paint film structure formation during and after spray application. The simulation program was validated by comparing simulations and leveling experiments. The influence of the initial film geometry and viscosity on the leveling behavior is demonstrated. For the investigations, model liquids and commercial paints with an increasing complexity of the physical properties were chosen: Newtonian flow behavior without solvent evaporation, Newtonian flow behavior with solvent evaporation, viscoelastic paints with non-Newtonian flow behavior. Four variants are proposed regarding how thixotropy can be measured and how a mathematical model can be created. The advantages and disadvantages of the variants with regard to the implementation of thixotropy in the simulations are listed. A method to predict the leveling behavior of thixotropic paints with simultaneous recovery of the viscous and elastic properties from rheological measurements using discrete relaxation time spectra is presented.     

Formulation effects on the distribution of pigment particles in paints

Modern water-borne paints are widely used in different areas of applications ranging from high-gloss lacquers to flat, scrub-resistant interior paints. From this point of view, the pigment volume concentration (PVC) is one key-parameter adjusting the desired application properties. In high-gloss paints, for example, a low PVC is required to accommodate the proper surface roughness to achieve a high gloss. Consequently, a high concentration of TiO₂ is needed to obtain a good hiding power at the same time. Flat paints nonetheless are highly filled due to cost reasons preferentially by CaCO₃ and the pigment binding capacity of the binder is crucial. In this work, paint formulations differing in PVC, and the type of binder or dispersing agent were investigated by various techniques concerning the distribution and aggregation of pigment particles, e.g. TiO₂. To get a detailed insight into the structure of the liquid paints and the corresponding dried paint films, suitable analytical tools were applied for characterization. The structure of the liquid paints was analyzed by remission light spectroscopy (RLS), disc centrifugation, cryogenic-replication transmission electron microscopy (Cryo-replica TEM) and cryogenic-scanning electron microscopy (Cryo-SEM). The pigment distribution in the corresponding dried paint films was examined by means of atomic force microscopy (AFM), TEM and RLS. The tendency of the TiO₂-pigments to form aggregates was found to depend on both: first on the type of binder used in the formulation and second on the employed dispersing agent. It is shown that only by adjusting the properties of the binder in combination with common dispersants, it is possible to get well-distributed TiO₂ particles within the paint. Correlation of application properties, e.g. gloss and blocking to the microscopic structure is presented.     

Antifouling paints II. A more detailed examination of the effect of pigment volume concentration

The effect of pigment volume concentration upon the leaching of soluble pigments from insoluble binders has been studied and the results used to extend a previously described¹ theoretical treatment. The number of interconnecting holes between the cavities left after solution of the pigment from the insoluble binder is assumed to be related to the pigment volume concentration in a similar way to the number of contacts made by smooth spheres regularly packed at the same solids content. An empirical equation is used to relate the number of contacts made between spheres to their density of packing, and consequently to relate the number of interconnecting holes between cavities to the pigment volume concentration. Predictions based on the resulting relationship are compared with the leaching characteristics measured for three different coating compositions, each made with a range of pigment volume concentrations using two different vinyl resins and two grades of copper (I) oxide pigment. The predicted variations with pigment volume concentration of initial leaching rate, and of initial rates of decrease in leaching rates, hold reasonably well for pigment volume fractions between 0.30 and 0.80, the full range studied. Longer term leaching behaviour appears predictable only for paints of pigment fractions above about 0.45; anomalies below this figure are attributed to lack of pigment solution. Statistical analysis of experimental leaching rate data indicate that the initial leaching rates are unaffected within limits by the type of binder and pigment. The two copper oxide pigments used behaved similarly. However, the kind of binder used does affect the rate of decrease in leaching rate. The experimental data is consistent with the theoretical model employed and with the concept that the thickness of binder separating pigment particles and hence the interconnecting hole size remains approximately constant irrespective of pigment volume concentration.     

Effect of precipitated calcium carbonate additions on waterborne paints at different pigment volume concentrations

Titanium dioxide (TiO₂) due to its high refractive index, is widely used in paint industry as a white pigment. In order to reduce this high cost of TiO₂, a part of TiO₂ is generally substituted by some other industrial mineral fillers such as calcite and calcined kaolin; however, this substitution affects the quality of paints in terms of stability, coverage (opacity), brightness (gloss), scrub resistance (film toughness), etc. In the present paper, precipitated calcium carbonate (PCC) was substituted for TiO₂ in paint mixture at three different pigment volume concentrations (PVC). It was observed that substitution of TiO₂ by PCC depends on PVC value at which there is an optimum PCC amount. The quality of paints produced by PCC along with its rheological properties was evaluated based on standard features in both wet and dry paints such as viscosity, density, opacity and gloss values. Addition of PCC increases the opacity to a certain point. Similarly, scrub resistance and viscosity increases with the addition of PCC at all PVCs, however, viscosity is not as much critical for the paint production. On the other hand, there is no any systematic effect of PCC on gloss value of the paint. This study overall demonstrates that PCC can be successfully used to substitute TiO₂ only with a careful adjustment of PVC and other extenders used in the paint formulation.     

醋酸乙烯-乙烯乳液用于低气味环境友好高性能涂料

介绍了醋酸乙烯-乙烯(VAE)乳液的技术基础,如VAE乳液的发展、合成技术、化学结构及性能优点。重点研究了在低VOC和低气味的环境友好内墙涂料中,VAE乳液与醋丙乳液、苯丙乳液对涂料性能的影响。结果表明:VAE乳液制备的涂料相对于使用低成膜温度的醋丙乳液涂料,具有更好的低温成膜性能和耐洗刷性能,并且在低PVC(颜料体积浓度)的涂料中具有更好的弹性;VAE乳液制备的涂料相对于低成膜温度的苯丙乳液,具有更好的对比率、低温成膜性和耐洗刷性。电子鼻分析仪的测试结果表明,VAE乳液制备的涂料比使用低气味苯丙乳液制备的涂料气味更低。     

An improvement of color electrophoretic paint via ultrafine modified pigment paste

The ultrafine paste used in electrophoretic paint was prepared via ultrasonic method with pigment yellow 83 (P.Y.83), octadecyl dimethyl benzyl ammonium chloride, and deionized water. The average particle size of the ultrafine paste was only 196?nm and zeta potential was 30?mV with ultrasound for 30?min and 2?wt.% cationic dispersant. The conductivity of the paint was improved as the cationic dispersant increased. Centrifugal stability of the paint with ultrafine paste reached the maximum at 2?wt.% cationic dispersant. Compared with the performances of cathodic electrophoretic paint with the ultrafine yellow paste, the anodic film was smooth, uniform, and neat with 0.5?wt.% cationic dispersant in the ultrafine yellow paste. Deposited amount of the anodic film was 27?g/m², which was higher than the cathodic film. The curing property, adhesion, and chemical resistance of the cathodic film were better than the anodic film. Properties of five color cathodic paints (blue, yellow, red, black, and green) were discussed and were compared with the film of electrophoretic paint containing commercial pastes. Except the green film, the blue, yellow, red, and black films were smooth, fine, and uniform, and also provided good L-effect. The deposited amount of these films with excellent adhesive force was about 14–19?g/m². The electrophoretic paints containing modified pigment pastes and commercial pigment pastes present good adhesion and chemical resistance.     

Thixotropic properties of yellow iron oxide-alkyd paints: their dependence on pigment-resin-solvent interactions

The effect of pigment content and the nature of the solvent on the thixotropic properties of synthetic yellow iron oxide in alkyd paints have been studied by viscometry. The degree of thixotropy of a paint has been calculated from the area of the thixotropic loop. The thixotropic effect in these paints is found to appear at about 35% PVC content and increases with the level of pigmentation up to 55 to 60% PVC content. The degree of thixotropy of paints also depends on the nature of the solvents used in the formulation. Interactions between pigment and solvent and between alkyd and solvent help in building structure and consequently in developing thixotropy in yellow iron oxide-alkyd paints. The shear dependence has been analysed using the Power law and the Casson equation.These paints exhibit only pseudoplastic flow behaviour and their consistency index depends on the pigmentation level and the solubility parameter of the solvent. Sag resistance depends on the PVC content and the nature of the solvent, but the brushability property is independent of these parameters.     

Desorption of copper from a copper-chitosan complex

Chitoson, a high molecular weight polymer, has the ability to sorb metals and form chitosan-metal complexes. A complex using copper has been prepared and its desorption characteristics have been studied. The slow release of copper is of potential use in anti-fouling paints and therefore the desorption of copper has been studied under various environmental conditions. Desorption rates were high in distilled water but low in sea water, and after further comparative tests with commercial marine paints, it was concluded that copper-chitosan complexes are not as effective as the cuprous oxide anti-fouling agent currently used in marine paint formulations.