62 HAPPI • December 2009 • www.Happi.com

UATERNARY alkyl ammoni-um salts have traditionallybeen the “workhorse” for thehair care industry. Mater-ials such as cetrimoniumchloride (CTAC), behentri-monium chloride (BTAC)and distearyldimoniumchloride (DSDC) havestrong substantivity to the

hair surface and provide the desiredconditioning properties. In addition, theuse of DSDC, including palmitamido-propyltrimonium chloride (PATC), wasfurther extended to skin care. They canact as cationic emulsifiers for oil-in-water lotions as well as creams provid-ing a typical powdery, smooth and dryskin feel. In sun care formulations,these cationic materials offer the bene-fits of low tackiness, high water resist-ance and excellent sand repellency.They are economical and cost effective.However, these materials have poorbiodegradability. In recent years, thesenegatives were further compounded bythe growing public awareness concern-ing the sustainable use of naturalresources. Formulators are looking forgreener solutions for their performanceneeds in hair and skin applications.Consumers are also looking for eco-friendly and sustainable products.Hence the need is emerging for creativetechnologies that are naturally derived,biodegradable, eco-friendly and sus-tainable while maintaining the good

performance of hair conditioning aswell as skin care properties.

To fulfill market needs, EvonikGoldschmidt GmbH has developed anew esterquat, distearoylethyl dimoni-um chloride (DSEDC), as an alterna-tive for alkyl quats with improvedbiodegradability and eco-toxicity.

Sustainable and Easy to HandleDSEDC is a vegetable-based quater-nary ammonium compound having twoC18 fatty acid chains with two readilyhydrolyzable ester linkages, representsa novel class of hair conditioning agents

and oil-in-water skin care emulsifiers.The inclusion of ester linkages into thealiphatic chains has significantlyimproved the kinetics of biodegradationof the cationic surfactants, lowering theenvironmental exposure levels.

The Evonik product (Varisoft EQ 65)is a blend of the esterquat DSEDC andcetearyl alcohol (DSEDC&CA). Theaddition of cetearyl alcohol enables theproduct to be pelletized (Figure 1). Thispellet product has high flash point andis easy to handle.

The biodegradation of DSEDC wasinvestigated over a 28-day period in aManometric Respirometry Test accord-ing to the guideline OECD 301 F. At atest concentration of 25mg/L, thebiodegradation of the product wasabove the official criteria of 60% withina 10-day window and can be classifiedas readily biodegradable. On the con-trary, the alkyl quats have very poorbiodegradability as demonstrated byCTAC in Figure 2.

Esterquat is typically preparedthrough reacting a (mono-, di- or terti-ary) alkanolamine with fatty acids, fol-lowed by reaction with an alkylatingagent to the corresponding quaternary.The esterification is carried out in thepresence of a catalyst, the raw materialsare heated up to 220°C to obtain highconversion and water removal isenhanced by stripping with an inert gasor under vacuum. The reaction timenormally depends on the reaction condi-tions and the reactivity of the compo-nents. The quaternization of correspon-ding ester-amine are carried out at tem-perature up to 100°C, and the reactioncan be completed in a few hours butmay take longer with less reactive ester-

Q

Evonik researchers detail the benefits of an eco-friendly and vegetable-basedesterquat for hair conditioning and skin care applications.

Brian Yang, Anna Howe, Angela Paez and Murat Quadir Evonik Goldschmidt Corporation

Hopewell, VA(804) 452-5672 or www.evonik.com/personal-care

Eco-Friendly, Vegetable-BasedEsterquat from Evonik

Fig. 1: Varisoft Esterquat

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amines. As shown in Figure 3, esterquatsynthesis requires less reaction stepsand milder reaction conditions thanthat of making alkylquats. The wholeproduction process consumes less ener-gy and generates less waste and istherefore more sustainable.

ApplicationsThis novel esterquat,DSEDC, is substantive toboth hair and skin. Itimproves the detanglingand wet combing of hairfiber while exhibitingsuperior dry combing anddry feel of hair. In compar-ison to the market stan-dard, cetrimonium chlo-ride (CTAC), it forms avery dense and richappearance of the finalconditioner formula. It al-so acts as an oil-in-watercationic emulsifier impar-ting a powdery, smoothand dry skin feel afterapplication even in highlipophilic loadings. Addi-tional special advantagesin sun care are low tacki-ness, high water resist-ance and sand repellency.

Conditioning AgentsHuman hair is composed of keratinousmaterial. Its surface has isoelectricpoint (IEP) around 3.7 and therefore, innormal condition, where the pH isabove the IEP, bears a net negativecharge with excess anionic groups. Thenegative charge density on hair surfaceincreases when hair is further dam-aged; e.g., by bleaching, or dying via theoxidization of cystine linkage, formingmainly cysteic acid, resulting a high

number of anionic groups. When hairis treated with cationic ingredients, theelectro-static interaction drives theseingredients to the hair surface.Esterquat DSEDC is highly substan-tive to hair providing the desired condi-tioning benefits such as improvementof wet and dry combing and feel, andantistatic properties.

Esterquat DSEDC&CA can be dis-persed in water at approximately 80-85°C. Addition of nonionic emulsifierssuch as Ceteareth-20 would improvethe processability of DSEDC&CA inwater, but is not mandatory. The for-mula below is an example of a simplebut very efficient eco-friendly andPEG-free conditioner formula withoutan additional emulsifier.

PEG-Free ConditionerIngredients %Wt.Varisoft EQ 65 (Evonik) 3.1(Distearoylethyl dimonium chloride (and) cetearyl alcohol)

Cetearyl alcohol 4.4Glycerin 2.0Water 90.5Perfume, preservative q.s.

DSEDC shows good stability at lowerpH. We have found that DSEDC as asingle ingredient is sensitive to neu-tral-alkaline pH. However, it is morestable in formulations. We recommendto formulate a cream rinse conditionerformulation with a typical pH between4 and 5, preferably below 4.5.

Technical half head tests with 10 pan-elists, which were performed by profes-sional hairdressers in an external testinstitute, verified the excellent condi-tioning properties of DSEDC. Thereinthe test formulations contained typical-ly 0.5% ceteareth-25, 5.5% cetearylalcohol and 2.0% active cationic condi-tioning agent. The pH value is adjustedto 4.5. The conditioning profile hasbeen compared against the marketstandard cetrimonium chloride as wellas against one of the most efficient con-ditioning quat, behentrimonium chlo-ride (See Figure 4a next page).

Figure 4a shows that for most provedparameters esterquat DSEDC clearlyoutperformed the market standardcetrimonium chloride.

Figure 4b shows that the conditioning

Fig. 2: DSEDC is readily biodegradable

Fig. 3: Synthesis process of esterquat compared to alkylquat

AcknowledgementThe authors thank Uta Kortemeier, HolgerLeidreiter, Hans-Juergen Koehle, KlausJenni, Sascha Herrwerth and BurghardGrüning, all of Evonik Goldschmidt GmbH.

64 HAPPI • December 2009 • www.Happi.com

properties of the esterquat DSEDC arevery similar to the highly efficientbehentrimonium chloride. These halfhead results will give formulators achoice to create conditioners with a bet-ter toxicological profile while maintain-ing performance.

Skin Care EffectsIn hair care formulations, cationicmoieties have typically been associat-ed with conditioning. In this applica-tion, they impart lubricity, antistaticproperties and smoothness to the hairfibers. These properties, plus excellentemulsifying properties, substantivityto the skin, renewable raw materialsand good cost/performance ratio areincreasing the interest in these wellknown ingredients for skin care appli-cations (Figure 5).

Sun Care and Sand RepellencyWith the increasing concern about suninduced skin damage, consumers areusing sunscreens at the beach andthroughout the year to protect theirskin from premature aging.

Although an oily feel is acceptablefor the beach, it is not acceptable fordaily wear—the challenge to formula-tors is to develop high SPF formulasthat protect the skin and wear well,but do not feel oily. The esterquat(DSEDC&CA) offers cosmetic chem-ists a novel biodegradable cationicemulsifier for their formulas toachieve the aesthetics along with theadditional benefit of water resistanceand sand repellency at low usage con-centrations.

The sand repellency study was car-ried out by applying 0.3g of the emul-sion to the dry, inner forearm of a pan-elist. After one minute the forearm issprinkled with 30mL of fine aquariumsand. The panelist then claps hishands three times to remove the sand.Sand that is left on the forearm isrinsed off, dried and weighed.

The results of the test indicate thatcationic emulsifiers, esterquat(DSEDC&CA) and distearyldimoniumchloride provided the best sand repel-lency (Figure 6). The excellent sandrepellency reduces the discomfortresulting from the sand sticking onthe skin, thus enhances the fun expe-

Fig. 4a: Half head test results–comparison between Esterquat(Varisoft EQ 65) and cetrimonium chloride (CTAC)

Fig. F4b. Half head test results with 10 panelists–comparingEsterquat (Varisoft EQ 65) and behentrimonium chloride (BTAC)

Fig. 5: Increasing number of cationic skin care products

rience of beach playing, especially forkids or adults who play beach sports.

Cationic Sun Care Lotion I, Sand-Repellent SPF* 8

Ingredients: %Wt.Distearoylethyl dimonium 6.00

chloride (and) cetearyl alcoholGlyceryl stearate 1.00

Mineral oil (30 mPas) 1.50Capryl/capric triglyceride 5.00Isopropyl palmitate 1.00Quaternium-80 1.00Ethylhexyl methoxycinnamate 5.00Octocrylene 3.00Butyl methoxydibenzoylmethane 2.50Glycerine 3.00Guar hydroxypropyl- 0.50

trimonium chloridePEG-150 distearate 1.50Disodium phosphate 0.12Water 67.88Phenonip 1.00

SPF* (in-vivo): 8; Star Rating: 3; WaterResistance**: 50%*(COLIPA Method, panel of 5 persons)**(Spa Pool Method Colipa Europe)

Cationic Sun Care Lotion II, Sand-Repellent SPF* 8

Ingredients: %Wt.Distearoylethyl dimonium 5.00

chloride (and) cetearyl alcohol

Glyceryl stearate 1.50C12-15 alkyl benzoate 7.00Diethylhexyl carbonate 5.00Cetyl rincinoleate 1.00Triisostearin 1.00Ethylhexyl methoxycinnamate 5.00Octocrylene 3.00Butyl methoxydibenzoylmethane 3.00Glycerine 3.00Ethanol 0.35Water 65.15Preservative q.s.

SPF* (in-vitro): 8; Star Rating: 3; WaterResistance**: 92%*(Optometrics SPF analyzer 290S; 1mg/cm2; on PMMA slide)**(Internal in-vitro method)

ConclusionEsterquat represents a novel class ofcationic product providing formulatorswith a new tool to develop productsthat meet consumer demands. �

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Fig. 6: A strong sand-repellentformula (left) vs. a weak sand-repellent formula (right).