Alkyds emulsification

Gooch, J.W., Emulsification and Polymerization of Alkyd Resins, Kluwer Academic/Plenum Publising, New York, 2002. 

The exercise of preparing emulsions using oils-mixed additives is well described in Emulsification and Polymerization of Alkyd Resins (Gooch 1980, 2002), although without the addition of acidic or cationic agents for the purpose of inhibiting or destroying bacteria. 

Several industrial systems involve emulsions, of which the following are worthy of mention. Food emulsions include mayonnaise, salad creams, deserts, and beverages, while personal care and cosmetics emulsions include hand creams, lotions, hair sprays, and sunscreens. Agrochemical emulsions include self-emulsifiable oils that produce emulsions on dilution with water, emulsion concentrates with water as the continuous phase, and crop oil sprays. Pharmaceutical emulsions include anaesthetics (O/W emulsions), hpid emulsions, and double and multiple emulsions, while paints may involve emulsions of alkyd resins and latex. Some dry-cleaning formulations may contain water droplets emulsified in the dry cleaning oil that is necessary to remove soils and clays, while bitumen emulsions are prepared stable in their containers but coalesce to form a uniform fihn of bitumen when apphed with road chippings. In the oil industry, many crude oils (e.g.. North sea oil) contain water droplets that must be removed by coalescence followed by separation. In oil slick dispersion, the oil spilled from tankers must be emulsified and then separated, while the emulsification of waste oils is an important process for pollution control. 

Other water-borne coatings include water-soluble emulsions, dispersions, and latex resins. Water-soluble resins are rare because most resins derived from vegetable oils are insoluble in water. The true emulsions are based on the emulsification of the oil or alkyd through either the action of a surfactant or a resin that has a surfactantlike character. The alkyd emulsions are readily prepared and can be used for OEM coatings and architectural applications. The submicron size droplets are stabilized by the thickeners (El-Aasser Sudol, 2004 Landfester, 2005 Landfester et al., 2004 Tsavalas et al., 2004 Weissenborn Motiejauskaite, 2000a,b). In dispersions, the resin is a solid and is dispersed in water. The latex resin is usually vinyl acetate, styrene, acrylates, or methacrylates radically copolymerized in a micelle to form particles 0.1 pm in diameter (Bloom et al., 2005 Brister et al., 2000 Jiratumnukul Van De Mark, 2000 Thames et al., 2005). 

Weissenborn, P.K. A. Motiejauskaite. Emulsification, drying and film formation of alkyd emulsions. Prog. Org. Coat. 2000b, 40, 253—266. 

Data on the preparation of alkyd emulsions by the phase inversion technique were presented in [211]. This technique is accomplished by adding water to an alkyd/surfactant mixture under formation of a stable emulsion. The determination of surfactant s solubility in water and alkyd phases allows to calculate the quantity of water required for phase inversion. Effective emulsifiers are ethoxylated sulphates (2-3 EO groups) of C12 - Ch and C16 - Cig higher alcohols. With these surfactants, the emulsification becomes less dependent on the temperature than with nonionic surfactants. 

Another common approach to water-based coating formulations is post-emulsification of a polymer in water. Several condensation polymers, e.g. alkyds, i.e. fatty-acid-modified polyesters, polyurethanes and epoxy resins, have been made into dispersions by the use of a suitable emulsifier and application of high shear. For instance, long oil alkyd resins of the type used in white-spirit-based formulations have been successfully emulsified by using nonionic surfactants such as fatty alcohol ethoxylates, alkylphenol ethoxylates or fatty acid monoethanolamide ethoxylates. Neutralization of alkyd carboxylic groups helps in producing small emulsion droplets and with the proper choice of surfactant, droplet diameters of less than 1 pm can be obtained. Such dispersions are sufficiently stable for most applications. 

Surfactants capable of participating in autoxidative drying are of interest for the post-emulsification of alkyd resins. Ethoxylated monoethanolamides of unsaturated fatty acids are one such type of surfactant that can be chemically incorporated into the network during drying... 

Autoxidative polymerization n. The reaction of oxygen with fatty acids, oils or other reactive materials to form higher molecular weight polymers (e.g., autoxidative polymerization of vegetable oils and emulsified vegetable oils). Gooch JW (2002) Emulsification and polymerization of alkyd resins. Kluwer Academic/Plenum Pubhshers, New York. 

The other approach is to dissolve or to emulsify the alkyd in water. Emulsification can be assisted by adding a surfactant, and also by making the alkyd partly water-soluble. Typically non-ionic surfactants are used. The alkyd may have an increased acid value and be partly amine neutralized, or may include water-soluble components (Chapter 9). The latter is now more usual. These emulsions are made by mechanical means (p. 158). 

Alkyds, oils and oil/alkyd mixtures have been emulsified and subsequently autoxidatively crosslinked in the emulsion form to a near-gel or gelled state within the polymer particles. During the emulsification, the emulsifier type was carefully... 

Table 8 lists the components of the formulation that were found to be suitable for the emulsification of alkali refined soya oil emulsion. Table 7 lists the components for the formulation of the alkyd emulsions. 

Fish Oil M A natural oil extracted firom fish and generally characterized by a rather large group of saturated fatty acids commonly associated with mixed triglycerides (Fish oil a key to better coatings, Manuf Eng Mag, October 15, 1987 Gooch JW (2002) Emulsification and polymerization of alkyd resins. Kluwer/Plenum Publishers, New York). The fatty acids derived from fish oils are three principal types saturated. 

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