Waterborne paint systems

For waterborne paint systems (especially emulsions used for decorative purposes) defoamers based on mineral oils are often used. In addition to the mineral oil as carrier, these products contain finely dispersed hydrophobic particles (e.g., silica, metal stearates, polyureas) as defoaming components. A small amount of silicone is sometimes included to intensify the defoaming action. For high-quality waterborne coatings in industrial applications, defoamers are used that contain hydrophobic silicone oils as the principal defoaming component instead of mineral oils. They have a better defoaming effect, but are more expensive. In most cases silicone defoamers do not cause the gloss reduction that is often observed with mineral oil products. 

In order to achieve maximum paint utilization, special electrostatic, high-rotation (HR) sprays are increasingly being examined for their specific apphcation potential, which in combination with the (highly conductive) waterborne paint systems also has a particular effect on the design of the entire paint supply system. The use of HR sprays for jpplying the basecoat is also being advanced... 

Chem. Descrip. Blend of proprietary surface-act. substances Uses Deaerator and leveling aid used in almost all solv.-based and waterborne paint systems, free of silicones also exc. performance in inks and coil coatings Properties Yel. liq. flash pt. (Abel) > 100 C ref. index 1.49 Use Level 0.5-2% on total formula Drewplus S-684 [Ashland Hercules Water Technologies]... 

Possible combinations of red lead with various binder systems are listed in Table 39 [5.114]. Red lead is still used for heavy-duty anticorrosion applications, especially for surfaces bearing residual traces of rust. In waterborne paints, red lead has no advantages over zinc phosphate [5.149]. 

The increasing importance of environmental considerations places new requirements on paint resins and has broadened the range of paint systems. Paints are now required that have a low solvent content (medium-solids, high-solids coatings) or are solvent-free (powder coatings), that can be adjusted by dilution with water (waterborne paints), and that are thermoplastic or capable of undergoing cross-linking. All of these properties must be obtained via the polymer structure of the binders. Important parameters are described below. 

Polymer Dispersions (Emulsion Polymers). Waterborne paints based on polymer dispersions (usually referred to as emulsion paints) are not water soluble. They are water-thinnable systems composed of dispersions of polymer particles in water (see Section 3.5). The particles consist of high molecular mass polymers (e.g., of styrene, butadiene, acrylate, or vinyl monomers) and are produced by emulsion polymerization. These waterborne paints also contain small amounts of organic solvents (< 5 wt %) that serve as film-forming (coalescing) agents that partially evaporate on drying. 

Corrosion-resistant and wear-resistant materials (e.g., stainless steel and in special cases suitable plastics) have to be used for the equipment required to produce and apply waterborne paints. This applies to production vessels, storage and transportation vessels, to the feed system used for application (e.g., closed circuit tanks, pipelines, and pumps) all of which must be able to withstand chemical mechanical stress. The use of corrosion-resistant materials for the spraying equipment is also advantageous. 

The stirrers are mainly of the flat-blade, disk, propeller, or turbine type [7.16]-[7.19]. Rotor-stator systems are also used as continuous mixers (Fig. 7.5). These machines are employed particularly if an emulsion or an emulsion-like product has to be produced (e.g., waterborne paints) [7.20]-[7.22]. 

The extremely high electrical conductivity and high dielectric constant of waterborne paints should be taken into account. The paint supply system must be electrically insulated to prevent short circuiting. Ionization charging or, in the case of automatic equipment, the installation of an insulated paint supply system have proved of value. 

Viscometers are being increasingly used for accurate measurements on modern industrial paints, especially waterborne paints. Rotating viscometers with a concentric cylindrical geometry (Searle system. Fig. 9.1) are advantageous for paints. Precise thermostatic control is easily achieved because the outer cylinder does not rotate. The drive and torque sensor are combined to form a single unit with the rotating inner cylinder. 

Field trials have shown that the expected durability of the new waterborne coating systems is equal to that of conventional solventborne paints. As a further advantage, the number of single coats can be reduced from three to two. Standard freight cars are painted with a three-coat alkyd system consisting of an anticorrosive primer, an intermediate coat, and a topcoat, total DFT is ca. 150 pm. Such systems are being replaced by single-coat systems of waterborne acrylic resins and acrylic copolymers to reduce solvent emission. 

Uses Dry film presen/ative for acrylic stucco systems, waterborne paints, and masonry stains fungicide/algicide for protection of dry film coatings and industrial fabrics... 

Chem. Descrip. Aq. soi n. of nonionic hydrophobe-modified poiymer Uses Thickener for water-based paints, esp. acryiic, styrene-acryiic, and vinyi-acryiic systems, and two-component waterborne epoxy systems Features For strong iow to mid shear rheoiogy exc. vise, stabiiity for tintabie systems Properties Nonionic Optiflo L100 [Sud-Chemie inc]... 

Most of the important types of modem solvent-borne coatings — epoxies, alkyds, acrylics — are also available in waterborne formulations. In recent years, even urethane polymer technology has been adapted for use in waterborne coatings [1]. However, waterborne paints are not simply solvent-borne paints in which the organic solvent has been replaced with water the paint chemist must design an entirely new system from the ground up. In this chapter, we discuss how waterborne paints differ from their solvent-bome counterparts. 

Latexes must always be applied at a temperature above the MFFT. This is more difficult than it sounds, because the MFFT is a dynamic value, changing over time. In a two-component system, the MFFT begins increasing as soon as the components are mixed. Two-component waterborne paints must be applied and dried before the MFFT has increased enough to reach room temperature. When... 

Stringent legislations concerning the amount ofVOCs in all paint types have caused many companies to seek alternatives to solvent-borne paint systems, making the move to waterborne systems, the main focus of which is to improve film properties to the level of conventional solvent systems. Hence, a combination of CCTP and emulsion polymerization was explored as a method of creating additives for waterborne paints. ... 

Uses Surf, additive, slip agent, leveling agent, substrate wetting agent in solv.-based, air drying, baking systems, e.g., alkyd-acrylic, polyester-melamine, waterborne paints, inks... 

K. Ito, T. Kato and T. Ona, Rapid viscosity determination of waterborne automotive paint emulsion system by FT-Raman spectroscopy, Vib. Spectrosc., 35, 159-163 (2004). 

Waterborne storage of damaged NS is accompanied by continuous contamination of water area. Only peeling of their rust and paint has resulted in persistent contamination of aquatic systems including bottom sediments. Specific activity of water exceeds the background values by a factor of 2 dose rate values on sea bottom reach 140 mR/h. 

Today, a large and increasing proportion of the automotive OEM metallic basecoats in Europe and North America are already waterborne and refrnish basecoats are also available in waterborne versions. Other paint applications have followed and the significant growth of waterborne systems can easily be seen in the statistics of the paint associations. Also in printing inks, the use of waterborne inks is steadily growing. 

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