Oil-in-Water Emulsifier

The ingredients are nonionic surfactants. It is their application as amine replacements in steam-condensate systems that is novel, not the raw materials. These products are commonly found in skin and hair products and in cosmetics because of their mildness and their excellence as water-in-oil emulsifiers and co-emulsifiers in oil-in-water emulsions. Raw material brands include Tween (ICI, PLC), Crill , and Crillet (Croda PLC). 

It is not always necessary to demulsify the water, however, because when small quantities are present in fine droplet form, the water explodes at the burner firing point, improving atomization of the fuel and providing for more complete combustion. Consequently, a water-in-oil emulsifier may be used to deliberately retain the water as small, emulsified droplets. The overall effec-... 

A special procedure is reverse emulsion polymerization. In this case, a hydrophilic monomer (e.g., acrylamide) is dissolved in water and the resulting solution is emulsified using special water-in-oil emulsifiers in a water-immiscible organic liquid (petroleum ether). Then the polymerization is initiated with a... 

A series of sorbitol-based nonionic surfactants are used in foods as water-in-oil emulsifiers and defoamers. They are produced by reaction of fatty acids with sorbitol. During reaction, cyclic dehydration as well as esterification (primary hydroxyl group) occurs so that the hydrophilic portion is not only sorbitol but also its mono- and dianhydride. The product known as sorhitan monostearate [1338 -1 -6], for example, is a mixture of partial stearic and palmitic acid esters (sorbitanmonopalmitate [26266-57-9]) of sorbitol, 1,5-anhydro-D-glucitol [154-58-8], 1,4-sorbitan [27299-12-3], and isosorbide [652-67-5], Sorbitan esters, such as the foregoing and also sorbitan monolaurate [1338-39-2] and sorhitan monooleate [1338-43-8], can be further modified by reaction with ethylene oxide to produce ethoxylated sorbitan esters, also nonionic deteigents FDA approved for food use. 

The phosphatides have polar and nonpolar sites, and generally act as water-in-oil emulsifiers. They are extracted by solvents with the oil, but preferentially will absorb available water, form gums, and precipitate. Commercial lecithin is produced by water degumming (precipitation from oil with ion exchange-treated water) as explained later. 

When the monomer is hydrophilic, emulsion polymerization may proceed through what s called an inverse emulsion process. In this case, the monomer (usually in aqueous solution) is dispersed in an organic solvent using a water-in-oil emulsifier. The initiator may be either water-soluble or oil-soluble. The final product in an inverse emulsion polymerization is a colloidal dispersion of a water-swollen polymer in the organic phase. 

Standard-grade (crude) lecithins are excellent water-in-oil emulsifiers. However, modified lecithins can function to emulsify either water-in-oU or oil-in-water emulsions, depending on the type of lecithin modification and the specific parameters of the system. These system parameters can include pH, types of components, component ratios, solids content, and others. Unlike crude lecithins, hydroxylated lecithins are stable in acid systems (pH 3.5). Fractionated lecithins can be manufactured for specific emulsion types. As lecithin s emulsifying activity is partially dependent on its phospholipid ratio, changing the ratio can alter its emulsifying capabilities (7). 

In an inverse emulsion polymerization, a hydrophilic monomer, frequently in aqueous solution, is emulsified in a continuous oil phase using a water-in-oil emulsifier and polymerized using either an oil-soluble or water-soluble initiator the products are viscous latices comprised of submicroscopic, water-swollen, hydrophilic polymer particles colloidally suspended in the continuous oil phase. The average particle sizes of these latices are as small as 0.05 microns. The technique is applicable to a wide variety of hydrophilic monomers and oil media. The inverse emulsion polymerization of sodium p-vinylbenzene sulfonate initiated by both benzoyl peroxide and potassium persulfate was compared to the persulfate-initiated polymerization in aqueous solution. Hypotheses for the mechanism and kinetics of polymerization were developed and used to calculate the various kinetic parameters of this monomer. 

In an inverse emulsion polymerization, an aqueous solution of a hydrophilic monomer is emulsified in a continuous hydrophobic oil phase using a water-in-oil emulsifier. The polymerization is initiated with either oil-soluble or water-soluble initiators. Figure 2 shows a schematic representation of this system. The formation of micelles is uncertain, but is portrayed speculatively. The hydrophilic part of the emulsifier molecule is oriented toward the hydrophilic dispersed phase and the hydrophobic part toward the hydrophobic continuous phase. The initiation of polymerization proceeds by a mechanism analogous to that of the conventional system and submicroscopic particles of water-swollen hydrophilic polymer are generated in the continuous oil phase. 

General. Aqueous solutions of hydrophilic monomers were emulsified in xylene using water-in-oil emulsifiers, and polymerized using oil-soluble initiators. Typical hydrophilic monomers were sodium p-vinylbenzene sulfonate, sodium vinylbenzyl sulfonate, 2-sulfoethyl acrylate, acrylic acid, acrylamide, vinylbenzyl-trimethylammonium chloride, and 2-aminoethyl methacrylate hydrochloride. Typical oil-soluble initiators were benzoyl and lauroyl peroxides. In some cases, water-soluble potassium persulfate was used, both separately and in mixtures with oil-soluble peroxides. Of the water-in-oil emulsifiers, one of the most effective was Span 60 (technical sorbitan monostearate. Atlas Chemical Industries, Inc.). 

Biisch G, Neuwald F. Metallic soaps as water-in-oil emulsifiers [in German]. J Soc Cosmet Chem 1973 24 763-769. 

Some oil-soluble emulsifiers affect the crystallization process and development of polymorphic forms of fats (4-8). Sucrose fatty acid ester or sucrose polyesters (SPE) and lecithins are well-known food emulsifiers (9,10). The main characteristics of lecithins and SPE useful in food applications are their oil-in-water and water-in-oil emulsifying properties, that result in dispersion with condensed milk and coffee whitener, and prevention of blooming in candy products and chocolate (7,9-11). But there are very few reports about two effects of SPE on the crystallization of fats and oils, i.e., enhancement and inhibition (12,13). 

Commercial products are mixtures of partial esters of sorbitol and its mono- and dianhydrides with oleic acid. They are generally insoluble in water and are used as water-in-oil emulsifiers and as wetting agents. The main sorbitan esters are listed in Table 6.7 together with a space-filling model of a representative component of sorbitan palmitate. 

Emulsion polymerization typically refers to the polymerization of a nonaqueous material in water. The polymerization of a water-soluble material in a nonaqueous continuum has been called inverse emulsion polymerization. The inverse emulsion polymerization technique is used to synthesize a wide range of polymers for a variety of applications such as wall paper adhesive, waste water fiocculant, additives for oil recovery fluids, and retention aids. The emulsion polymerization technique involves water-soluble polymer, usually in aqueous solution, emulsified in continuous oil phase using water in oil emulsifier. The inverse emulsion is polymerized using an oil- or water-soluble initiator. The product is a colloidal dispersion of sub-microscopic particles with particle size ranging from 0.05 to 0.3 pm. The typical water-soluble monomers used are sodium p-vinyl benzene sulfonate, sodium vinyl sulfonate, 2-sulfo ethyl acrylate, acrylic acid, and acrylamide. The preferred emulsifiers are Sorbitan monostearate and the oil phase is xylene. The proposed kinetics involve initiation in polymer swollen micelles, which results in the production of high molecular weight colloidal dispersion of water-swollen polymer particles in oil. 

Alcohol fractionation of deoiled lecithin provides alcohol-soluble and alcohol-insoluble fractions enriched with PC and PI respectively. The PC-enriched fraction is an excellent oil-in-water emulsifier. The Pi-enriched fraction is a good water-in-oil emulsifier often used in the chocolate industry to increase the viscosity of the mass, therefore reducing the need for cocoa butter. The typical composition of these lecithin products is shown in Table 2.11. 

Sorbitan esters can be produced by transesterification in the presence of basic catalysts [104], This process does not, however, give satisfactory results-dehydra-tion of sorbitol is incomplete and, therefore, sorbitol esters can be the major products [105], Nowadays the acid-catalyzed direct esterification is the major route practiced in industry. Under these conditions both intramolecular dehydration and esterification occur to satisfactory extents [106]. When fatty acids in large excess are reacted for longer times sorbitan triesters are formed these can be used as water-in-oil emulsifiers. 

Sorbitan derivatives consist of esters of cyclic anhydrides of sorbitol with a fatty acid (C12-C18). They are named sorbitan esters. They are lipophilic surfactants used as water-in-oil emulsifiers. When these sorbitan esters are polyoxy-ethylened they are called polysorbates. A large range of properties may be obtained by varying the number of oxyethylene groups in the molecule. They have mainly oil-in-water emulsifying and solubilizing properties. Some sorbitan derivatives that are USP/NF-, Eur. Ph.-, BP-compIiant and FDA-approved for oral administration are listed below ... 

Stearic acid amine saponified from triethanolamine and stearic acid acts as a strong oil-in-water emulsifier, and glycerin is a weak water-in-oil emulsifier. Glycerol and ethylparaben are humectant and antiseptic, respectively. 

Various refined, modified or otherwise processed grades of commercial lecithin are available (e.g. fractionated, phosphorylated, acylaled, hydroxylated and hydrogenated), with consequent differences in composition and physical properties. Liquid, plastic or free-flowing forms can be made. Modified lecithins can function as both oil-in-water and water-in-oil emulsifiers. Hydrogenated varieties have reduced proportions of unsaturated carbon chains in the phospholipids, and are therefore more stable towards oxidation (Table 12.46). 

In contrast to these oil-in-water emulsions, it is possible that the emulsion polymerization can also be carried out with inverse emulsions. Inverse (water-in-oil) emulsion polymerization in which an aqueous solution of a water miscible hydrophilic monomer such as acrylamide, acrylic add, or methacrylic acid is dispersed in a continuous hydrophobic oil phase with the aid of a water-in-oil emulsifier such as sorbitan mono-oleate or -stearate. The emulsifier is ordinarily above the CMC. Polymerization can be initiated with either oil-soluble or water-soluble initiators. If an oil-soluble initiator is used, the system is an almost exact mirror-image of a conventional emulsion polymerization system. The final latex is a colloidal dispersion of submicroscopic, water-swollen particles in oil. This type of emulsion pol3unerization enables the preparation of high molecular weights water-soluble polymers at rapid reaction rates. It is also possible that the water-swollen polymer particles produced by this emulsion pol)nnerization transfer to aqueous phase rapidly by inversion of the latex. 

Sorbitan esters of fatty acids are well known as biodegradable water-in-oil emulsifiers which are particularly mild to the skin. They are used, inter alia, as emulsifiers for pharmaceutical and cosmetic formulations, as pigment dispersants in coatings and inks and as emulsifier for mineral oils and white oils in defoamer, synthetic lubricant and metal treatment formulations. Sorbitan monolaurate is employed as an antifogging agent for synthetic resin films and sorbitan monostearate and sorbitan mononooleate as emulsifier for inverse emulsion polymerization. 

ALROSPERSE 100 is an exceptionally effective water-in-oil emulsifier for use both with aliphatic hydrocarbons and chlorinated solvents. 

Effective water in oil emulsifiers and lubricity additives for the cutting fluid and drawing compounds manufacturer. Effective sperm oil replacement. 

Commerdal products are mixtures of the partial esters of sorbitol and its mono-and di-anhydrides (13.2). Several sorbitan esters can be identified (Table 13.2). Such esters are water insoluble (low HLB) and oil soluble, and are used as water-in-oil emulsifiers. 

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