Clouding hydrotropes

Any species that enhances the solubility of another. Example hydrotropes such as alkyl aryl sulfonates (e.g., toluene sulfonate) are added to detergent formulations to raise the cloud point. 

The cloud point of the high 2-phenyl product remains below 0°C up to 25% LAS whereas the low 2-phenyl cloud point is 15°C. In practice, this means that a formulation based on L2P surfactant would need higher additions of solvent or hydrotrope to keep the solution clear and stable at lower temperatures. 

Applications. Sarcosinates show low irritation potential and are good foamers. Due to these properties they find applications in personal care products where synergistic effects with other surfactants may also be exploited. In combination with other anionics, sarcosinates will often detoxify the formulation and give improved foaming and skin feel. Sarcosinates are also used for their hydrotropic properties - the addition of sarcosinate to other anionics often gives a reduced Kraft point or a raised cloud point if combined with non-ionic surfactants. Lauroyl sarcosinate is used to formulate SLS-free toothpastes which are claimed to have improved taste profile. 

The recent investigation [71] of a nonionic system, hexaoxyethylene dodecyl ether and water, showed a hydrotrope molecule to be introduced into the micelle first at concentrations at which the hydrotrope self-associates.This increase of the minimum concentration at which the hydrotrope molecule enters the micelle from the values in ionic systems [61-66] is in all probability due to electrostatic effects. One essential result of the investigations into nonionic systems [71] is that the presence of the hydrotrope reduces the size of the micelle i.e., the radius of the curvature toward the hydrophobic region is reduced and, hence, the cloud point is enhanced in accordance with the views of Shinoda and Arai [70], Investigations of block copolymer systems [72-76] may now be interpreted in a similar manner and the coupling or linking action of a hydrotrope in a nonionic system is given a simple explanation in the form of a modified micellar structure. 

These results have added to the understanding of the action of hydrotropes in the clouding in aqueous solutions, but have also had a significant influence on other... 

Hydrotropes are often added to an LDLD to help solubilize certain surfactants or other materials that are not easily soluble in water to ensure the stability of the formulation. The fundamental properties of hydrotropes and their hydrotropic action in liquid detergents are discussed in Chapter 2. The addition of a hydrotrope affects the formula viscosity and cloud/clear points. 

The cloud and clear points of an LDLD can be adjusted using hydrotropes [83,84] such as sodium xylene sulfonate (SXS), sodium cumene sulfonate (SCS), alcohols, or urea. Figure 7.4 illustrates the significant effect of SXS on the clear point of an LDLD formulation. 

Short-chain alkyl polyglycosides (C4-C10), because they have the large hydrophilic head group and short hydrophobic group needed to disrupt liquid-crystalline phases, are also effective hydrotropes. The Cs and C10 homologs are very effective in raising the cloud points (Section IIIB below) of some alcohol ethoxylates (Matero, 1998). 

Hartotrope. [Hart Chem. Ltd.] Sulfonates hydrotrope, detergent solubilizer, cloud pt dqpiessant for It duty and built liq. detergent systems. 

Ammonium xylenesulfonate Ammonium xylene-sulphonate Benzenesulfonic acid, dimethyl-, ammonium salt EINECS 247-710-9 Eltesol AX 40 Hartotrope AXS Naxonale 4AX Stepanate AXS Xylenesulfonic acid, ammonium salt Hydrotrope, cloud point depressant, stabilizer, solubilizer used in formulating detergents, inks, electroplating baths, dyestuffs, polymers. Albright Wilson UK Ltd. Hart Prod. Ruetgers-Nease Stepan Canada Stepan. 

Definition Potassium salt of xylene sulfonic acid Empiricai CsHgOsS K Properties M.w. 224.33 anionic Toxicoiogy TSCA listed Uses Hydrotrope, solubilizer, coupling agent, vise, modifier in liq. formulations hydrotrope in light-duty liq. detergents cloud pt. depressant in detergent formulations surfactant in cosmetics Trade Name Synonyms Eltesol PX 40 [Huntsman Surf. Sciences http //www. huntsman. com/surface sciences] Eltesol PX 93 [Huntsman Surf. Sciences http //www. huntsman. com/surface sciences]... 

Figure 14.12. Required amounts of hydrotropes needed to obtain a cloud point of 70°C, shown for alkaline (a) and neutral (b) formulations...

Figure 18.7. The cloud points for solutions with 1 % nonionic surfactant and hydrotrope, respectively. The following surfactants have been used ( ) C6EO2 (A) C11EO5 ( ) C13EO6. (Redrawn from data from Matero et ai, J. Surf. Del, 1, 485-489 (1998), The American Oil Chemists Society)...

Surfactant solubilization in liquid cleaners may be limited due to a high concentration of the surfactant or a high amount of electrolytes present in the formulations. In order to enhance the solubility and to increase the cloud point for nonionic-based systems, hydrotropes are often added. This phenomenon has already been pointed out in Section 3.5 above, where the cloud points of solutions with nonionic surfactants were elevated upon the addition of alkyl polyglucosides (16). Hydrotropic activity can be evaluated by determining the amount of hydrotrope required to clarify a cloudy solution or the cloud point elevation obtained for a specific concentration of a hydrotrope. The efficacy of hydrotropes varies for different classes of compounds. This has been observed for short-chain alkylbenzene and alkylnaph-thalene sulfonates when added to a number of detergent formulations (21). The alkylnaphthalene sulfonates were found to be more efficient than the alkylbenzene sulfonates in elevating the cloud point. 

Another important property of hydrotropes is their ability to interact with surfactants and modify their association in water. Particularly, hydrotropes increase the cloud point of ethojylated surfactants, i.e. the temperature at which the surfactant solution separates into two immiscible phases. Hydrotropes are also able to destabilise and eventually break down the liquid crystalline phases formed by the surfactants at higher concentrations and thus promote fluid formulations. ... 

At lower surfactant concentrations, the same hydrotropes are able to increase the cloud temperature, which is 48.1 °C at 2% wt. for the surfactant considered. Particularly, a 10% Dimethylisosorbide-solution is able to increase the cloud point of the surfactant solution of 12 °C. 

A hydrotrope, a solubilizer used to lower cloud point and viscosity. Especially good for dry compounding. 

A hydrotrope, used as a dispersing aid and as a solubilizer for lowering the cloud point and viscosity of liquid detergent solutions. 

FIG. 9 Cloud point modification of nonyl phenol ethoxylate (EO = 9) in 5% NaOH with Cg and Cjg alkyidiphenyl oxide disulfonates and common hydrotropes. 

Uses Hydrotrope, soii reiease improver, detergenL cloud pt. increaser for textile scours effective aiuminum corrosion inhibitor Features Patented hydroiytic stabiiity surfactant compat. reduces or eliminates the use of hydrotropes in detergent formulations Properties Amber Iiq. si. odor misc. with water m.p. 0 C b.p. > 100 C pH 6.5-8.5 noncombust. 34-36% total solids... 

Uses Solubilizer, emulsifier for soivs, oils hydrotrope polar solvent Reguiatory Australia AlCS Canada DSL Korea ECL JCIC Europe EINECS Properties Cl. yel. liq. dens. 0.868-0.872 hyd. no, 195-204 cloud pt. 5-8 C pH... 

Uses Hydrotrope, cloud pt. depressant in detergent mfg. solubilizer coupling agent... 

Uses Surfactant, coupling agent, hydrotrope, cloud pt. reducer for alkaline-built nonionic cleaning formulations... 

Uses Nonfoaming surfactant, hydrotrope effective over wide range of electrolyte cones. couples nonionics into heavy-duty built alkaline cleaners controls cloud pt. in anionic/nonionic systems rec, for household and industrial detergents, e.g., bottle washing, high-pressure spray cleaners, alkaline degreasers, transportation cleaners, hard surf, cleaners stable in acid and alkaline systems Properties Gardner 3 cl. liq. sol, in 25% NaOH, 30% KOH, 20% HCI, 50% phosphoric acid pH 8.7 50% act. 

Uses Coupling agent, hydrotrope, solubilizer, solvent In org. polymers and dyestuffs, petrol. Industry, pulping, animal glues solubilizer, hydrotrope for textiles dispersant, stabilizer, cloud pt. reducer, vise, reducer In llq. detergents Features Exc. cost/performance characteristics... 

Uses Corrosion inhibitor, detergent, solubilizer, hydrotrope for sol. oils, syn. fluids, cleaners in metal working, surface treatment Properties Colorless to yel. liq. Gardner color 3 max. cloud pt. 40-65 C pH (as is) 8-10 oven solids (2 h 105 C) 49-51%... 

Uses Hydrotrope, solubilizer, and detergent for hand dishwashing liqs., fine fabric liqs., metal cleaners, glass cleaners, concrete wall cleaners Features Compat. with cone, eledrolyte sol ns., strong alkaline medium, and acidic sol ns. no cloud pt. so its surf, props, not affected by high temps. stable foaming props. 

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