cosmetics

Chapter 5

Chemistry, Formulation, and Performanceof Syndet and Combo Bars

Marcel Friedman

Neca Chemicals, Agis Group, Israel

Introduction

Soap is undoubtedly the oldest surfactant and skin cleanser. For thousands ofyears, soap has been obtained from saponification of oils and fats by alkalitheoldest recipe being boiling animal fats and wood ashes. Soap is chemically definedas the alkali salt of fatty acids. In general parlance, the term soap has taken on amore functional definition, by which any cleansing agent, regardless of its chem-istry, is considered a soap. This sometimes misleading definition will be furtherconsidered as this chapter deals with the chemistry of the synthetic detergents andthe soapless soap revolution. Conventional soaps that are alkaline salts of fattyacids are characterized by multiple attributes, such as very good emulsification,detergent, and usage properties, as well as ease of manufacture and low cost.

Conventional soaps suffer from two main disadvantages. Soaps hydrolyze inwater and release caustic alkali. This subsequently increases the pH of the alkaliretained in soap during manufacturing. The high pH of natural soaps affects theskins natural acidic protective mantle by changing the skins pH (originallybetween 5 to 6.5). Even if the pH is restored relatively quickly after washing, thisis probably the main cause of the well-known negative soap effect. Another majordisadvantage of natural soap, first perceived during the second World War, is itsbehavior in hard or salt water. When water is very hard or contains a high level ofelectrolytes (such as seawater), the foaming performance and the cleansing effi-ciency of soap are seriously inhibited, if not eliminated, as natural soap formsinsoluble and inactive salts in the presence of magnesium and calcium, containedin hard water:

2 RCOONa + Mg++ (RCOO)2Mg + 2Na+

2 RCOONa + Ca++ (RCOO)2Ca + 2Na+

In addition, the insoluble salts precipitate on the surfaces of sinks and bathtubs as agray fatty mass that is unsightly and difficult to remove. Unfortunately, the identical

Copyright 2004 AOCS Press

phenomenon happens during skin cleansing, on which calcium and magnesiumsalts precipitate. The dermatological drawback of this is obvious.

The synthetic surface-active agents (surfactants) do not have these importantdisadvantages, and it is for this essential reason that they have been used in themanufacture of dermatologically recommended syndet bars, also known as soap-less soaps or alkali-free cleansing bars. Surfactants are also used in combinationwith soap for the formulation of combo (also called combi) bars. Initially thesurfactants were included as minor ingredients to disperse lime soap, and then asco-surfactants at higher percentages.

Soap pH

Conventional soaps neutralized with caustic alkali (sodium hydroxide) have analkaline pH between 10 to 11 (Lux, Palmolive, Camay, or Ivory) or between 8.5 to10, when they are partially neutralized with milder alkali amines, such as tri-ethanolamine (Neutrogena). According to their formulation the popular combobars have a pH between 8.5 to 10.0 when the major cleansing agent is soap (suchas Lever 2000, Zest, Nivea Milk Bar, or Satina) or even as low as pH 7.5, whenonly a small amount of soap is incorporated (Dove, Caress, or Olay).

Pure soap-free syndets have a pH between 5.5 to 7.0, matching the pH of theskin (i.e., Neca 7, Vel, Eubos, Sebamed, Ph 5 Eucerin, or Basis Ph). For this reasonit is believed that the syndets impact on the natural physiological skin equilibriumis extremely limited, making it the product of choice for cosmetic and baby cleans-ing bars. In particular applications, primarily medicated/dermatological, the pH canbe even lower, between 3.5 to 5.0, for example in iodine cleansing bars (such asNeca Polydine) in which the iodine complex is shelf stable only in acidic media. Asyndet base has the particular advantage of being the most pH suitable media forsuch applications. Figure 5.1 shows the pH ranges of the various bars.

Fig. 5.1. Cleansing formulations and pH range.

pH


Chemistry of Synthetic Surfactants

A surface-active agent is defined as a chemical substance that, even at low concen-tration, absorbs at the surface, reducing the free surface energy at the interface ofany two-phase system, such as gasliquid, liquidliquid, or liquidsolid. Toachieve this, the surfactants must dissolve in each of the two phases. This isaccomplished by the presence of two distinct groups in their molecular structure.In a water-oil system, one group will be easily soluble in water (hydrophilic); theother will be insoluble in water (hydrophobic) but soluble in oil (lipophilic). Thebalance between hydrophobic and hydrophilic features governs the application ofthe surfactant as a detergent, wetter, or emulsifier.

A known scale, characterizing the surfactant according to its hydrophilic-lipophilic balance (HLB), was presented by Griffin. According to this system,highly hydrophobic surfactants have low HLB values, starting at 1, whereas highlyhydrophilic molecules are given high HLB values, up to 40. Detergents, forinstance, have values in the range of 13 to 15, compared to only 4 to 6 for water-in-oil emulsifiers.

There are four main types of surfactants, classified by the nature of theirhydrophilic head: anionic, cationic, amphoteric, and non-ionic. The first three arecharged molecules. Anionic surfactants possess a negative charge that has to beneutralized with an alkaline or basic material before full detergency is developed.Cationic surfactants are positively charged and therefore have to be neutralized bya strong acid before they can develop surface properties. Amphoterics include bothacidic (negative) and basic (positive) groups in their molecules and are positivelyor negatively charged, according to the pH of the solution. The non-ionic surfac-tants contain no ionic constituents, and have no electric charge (Fig. 5.2).

Soap is the simplest anionic surfactant. Since the saponification reaction is asimple hydrolysis of natural materials, soap is often considered a natural surfac-tant. All other surfactants, obtained by many simple or highly sophisticated reac-tions, are considered synthetic surfactants. Like soap, most surfactants used in per-sonal cleansing bars are anionic. A list of the anionic surfactants (including soap)that are used as active ingredients in cleansing bars is given in Table 5.1.

Fig. 5.2. Diagram ofsurfactant types andcharge distribution.


Surfactant synthesis can be straightforwardgetting a surfactant that is easilymixed into the formulation blend. But the more exciting and skillful cost-to-perfor-mance formulations are based on in one pot in situ manufacturing techniques,that by the nature of their by-products or reactant excess, will determine the finalformulation. The most brilliant example is the Dove formulation that exploitedthe fatty acid excess, used to shift the reaction equilibrium of sodium cocoylisethionate (SCI) synthesis, cosmetically presenting it as a moisturizing cream. TheSCI synthesis is presented in Figure 5.3.

The old fatty acid chloride route (1,2) has been made more economical with manydifferent synthetic and catalytic routes covered by several patents; some are referenced(36). Special care must be taken to inhibit transesterification between isethionate andstearic acid that are added later (5). Lower molecular weight fatty acid reactantsvolatilized during the reaction are continuously supplied to the reaction mass (6).Recently a batch and continuous process was disclosed to prepare soap-acyl isethion-ate composition with ratios as high as 20:1; it requires a hot (180200F) caustic solu-tion premix of sodium isethionate (7). Catalytic processes introducing new metallicoxides and heavy metal salt catalysts that require temperatures lower than 200C, haveno yield or reaction rate reduction, improve energy usage, and improve odor and colorhave been claimed (8). The synthesis of main sulfonates (LABS, -sulfo fatty acidesters) and sulfates (alkyl sulfates) by SO3 sulfonation are presented in Figure 5.4. The

TABLE 5.1Anionic Surfactants Used as Active Ingredients in Cleansing Bars

Surfactant Name Chemical Formulaa

Sodium carboxylate (soap) RCOONa, RCOOMgAlkyl sulfate ROSO3Na, ROSO3KAlkyl sulfosuccinate ROCOCH(SO3Na)CH2COONaAmido sulfosuccinate RCONHCH2CH2OCOCH(SO3Na)CH2COONaAcyl isethionate RCOOCH2CH2SO3NaAlkyl glyceryl ether sulfonateb ROCH2CHOHCH2SO3NaMonoglyceride sulfate RCOOCH2CHOHCH2OSO3NaLinear alkyl benzene sulfonate RC6H5SO3Na-Sulfo fatty acid esters RCH(SO3Na)COOCH3Acyl taurate RCON(CH3)CH2CH2SO3NaAlkyl sulfoacetate ROCOCH2SO3NaAcyl sarcosinate RCON(CH3)CH2COONaAcyl glutamate RCONHCH(COONa)CH2CH2COONaAlkyl ether sulfate RO(CH2CH2O)13SO3Na-Olefin sulfonate RCH=CHCH2SO3Na, RCHOH(CH2)23SO3NaAlkyl ether carboxylate RO(CH2CH2O)3CH2COONaParaffin sulfonate RCH2CH2SO3NaAcyl lactylate RCOO(CHCH3COO)13NaaR = C8C22, preferably C12C14 for lathering (mild) surfactant, and C16C18 for less lathering, milder ones.bAlso appears as alkoxy hydroxy propane sulfonate.


preparation of alkyl and alkanolamide sulfosuccinate by sodium sulfite sulfonation isshown in Figure 5.5.

Sulfonation chemistry is well covered in the literature (9,10). The hydrophobicchain length, neutralization media, and other parameters govern product suitabilityin solid-lathering formulations. For isethionates, the synthesis of nearly anhydroussulfosuccinate in the presence of melted plasticizers and in situ preparation withanionic surfactants, plasticizers, and a small amount of water have been suggestedas a straightforward method to manufacture a syndet base (11,12). The synthesis ofsome other surfactants such as sodium coco monoglyceride sulfate, that had beenpart of Colgate U.S. Vel brand (13,14), acyl glutamate (extensively used inJapan), and acyl sarcosinate are illustrated in Figure 5.6. Emphasis on chemicalstability of the different hydrophylic moieties is important; it is necessary to com-pare carboxylate susceptibility to alkaline hydrolysis or sulfate hydrolysis underacidic conditions to the chemical stability of the sulfonates.

Fig. 5.3. Synthesis of sodium cocoyl isethionate.


Formulation of Cleansing Bars

The list of surfactants presented in Table 5.1 shows a few of the hundreds of syn-thetic detergents and innumerable plasticizers, binders, moisturizers, and fillersavailable to formulate syndets and combo bars. The formulation of cleansing barsalways involves a skillful combination of scientific thought and almost artistic cre-ativity when selecting appropriate ingredients. The challenge for a soap formulatorgoes far beyond the manufacture of an effective cleansing agent.

In order to fulfill consumer expectations, a broad range of qualities is demand-ed of a bar. Social, economic, and psychological demands have advanced alongwith cosmetic skin care and environmental awareness. This has been followed bysubstantial cosmetological, dermatological, and technological progress that allowsthe availability of the sophisticated multifunctional products that is found today.Following these trends, the formulation of syndet and combo bars has become acomplex challenge, since final qualities and requirements, including their perfor-mance evaluation, are many and occasionally conflict (Table 5.2).

The different test conditions vary based on the test performed, but they havebeen standardized. Evaluation methods are elaborated according to the companys

Fig. 5.4. Sulfonation/sulfation reactions by sulfur trioxide.


expertise or official methods and are always aiming for an objective measurementof realistic usage simulation (15,16). The state of the art in most of the recentpatents is based on evaluation by human panels (17,18). These panels, rangingfrom expert evaluators in the laboratory through small- to large-scale consumerpanels, are obvious for sensory evaluation; they are also used extensively for lath-ering, slipperiness, rinsing, or mush/smear appreciation (6,17,18).

Processing

Syndet bar processing is more difficult than combo bars and conventional soaps.The syndet products have a very narrow temperature range in which the plasticitypermits proper refining and extrusion. Also due to the sticky and occasionally softcharacteristic of the extruded product, stamping rates are adversely affected. Thereare several types of finishing lines, but for syndet products it is best to have a linethat consists of a mixer, simplex refiner plodder, three-roll mill, and a duplex vacu-um plodder. A detailed overview of bar soap finishing lines and equipment can befound in Baggini, Nizzero, and Spitz (19). A main water chiller should supplycooling water to the line, and each machine should have its own independent cool-ing water temperature control unit. The soap press must have a low-temperatureglycol/water die chiller and independent low-temperature controller unit for eachstamping die group. A pilot-scale method to produce a syndet bar with long-chainalkyl sulfates for improved processability and bar characteristics is available (23).

Fig. 5.5. Synthesis of alkyl and alkanolamide sulfosuccinate.


The processing sequence comprises crutching, drying, amalgamating, milling(optionally), plodding, and stamping. A hygroscopicity test to evaluate processabil-ity is explained and examples are given. The higher the hygroscopicity, the stickierand more difficult to process a material tends to be (23).

Product Composition

To achieve all the requirements and properties, a suitable syndet/combar is essen-tially composed from a blend of ingredients as listed in Table 5.3. An ingredientcan have multiple and interchangeable functions. So binders absorb some of thewater, bind the various ingredients together, plasticize the mass, and act as an

Fig. 5.6. Anionic surfactant synthesis.


emollient. A good example of such functionality is high molecular weight polyethy-lene glycol that is also defined as a structurer (20). Moisturizers and emollients areused synonymously.

Surfactants

Surfactants are primarily responsible for cleansing and lathering. Beside the anionicsurfactants already reviewed in Table 5.1, nonionic and amphoteric surfactantsused and seldom quoted in the patents are listed in Table 5.4 (2131). The non-ion-ics also act as cleansers and plasticizers, but that depends on their HLB values.

A comprehensive list of surfactants, plasticizers, and binders was compiled byHollstein and Spitz (21). The state-of-the-art of patent literature, 15 years ago,showed that almost every existing surfactant is a potential active ingredient in syn-dets. In fact most of the patents cover the use of almost any surfactant, defining

TABLE 5.2 Product Performance Evaluation

In addition to cleansing, color, and odor, which were always thought of as main attributes forconsumer acceptance, the main bar performance evaluation parameters are:

1. Lathering (amount, stability, quality, density, speed of formation)2. Mushiness/sloughing/smearing3. Erosion/wear/use-up rate4. Hardness5. Rinsability (from skin and bathtub)6. Physical stability (wet and dry cracking)7. Chemical stability (odor, color, efflorescence)8. Skin feel (during and after rinsing/drying)9. Lather feel during washing

10. Mildness/dermatological compatibility11. Processability/workability

TABLE 5.3 Ingredients of Syndet/Combo Bars

Ingredients Range (%)

Surfactants 3070Plasticizers, binders, emollients 2050Lather enhancers 05Fillers 530Water 512Fragrance 01.5Mildness enhancers 05Opacifying agents 00.3Antibacterial, deodorant agents 02


even the potential of using any lathering mild synthetic surfactant that lathers atleast about as well as the mild standard alkyl glyceryl ether sulfonate (17).

Some compositions are given in Table 5.5, which partly illustrates the presentstate-of-the-art and has to be seen as complementary to previous lists (21). During thelast few years newly patented (59) sulfo methyl esters (SME) have been promotedcommercially by Stepan Company (U.S.) for the formulation of combo bars (60).

TABLE 5.4 Nonionic and Amphoteric Surfactants

Surfactant Name Reference

Alkyl polyglucosides 31Fatty alcohols 21Alkyl phosphate esters 25,26Ethoxylated alkyl phosphate esters 25,26Methyl glucose esters 24,25,29Sucrose esters 21Imidazoline amphoterics 21Glyceryl monostearates 21Protein condensates 24,26Alkyl phenol polyethylene glycol ether 22Polyethoxylated fatty alcohols 23,27Polyalkylene glycols (PEG) 28 Alkyl betaines 29Alkyl sultaines 29Alkyl amine oxides 29Polyhydroxy fatty acid amides 30

TABLE 5.5 Surfactant Composition in Combo/Syndets

Composition (%) Reference

Magnesium soap (550%) + any surfactant (2050%) 17Soap (4590%) + polyethoxylated fatty alcohol (18%) 27Alkyl glyceryl ether sulfonate (3580%) + soap (125%) 18Aldobionamide (2075%) + polylalkylene glycol (1565%) 28Soap (5090%) + any surfactant (120%) 29Soap (7585%) + polyhydroxy fatty amide (110%) 30Soap/fatty acid (1050%) + any surfactant (2065%)a 24,25a

Soap (7085%) + alkyl ether sulphate (110%), alkyl polyglucosides (0.110%) 31Soap/fatty acid (550%) + any nonionic/anionic surfactant (1565%) 26a

Acyl isethionate (4570%) + vegetable oil (0.52.5%) 32PEG (7080%) + lauryl sulphate/amphoteric (830%)a 33a

Sodium lauryl sulphate (7090%)a + binder 34b

Long-chain alkyl sulfate (1855%) + soap (120%) 23aRefers to framed/molded bars.bPresented as solid shampoo composition.


Some patents propose the use of new surfactant molecules. For instance, a nonionicglycolipid surfactant (more specifically an aldobionamide) at 2075% in a composi-tion structured by 1565% polyalkylene gycol (preferably PEG of molecular weight600010000) and containing no more than 15% fatty acids (28). Unfortunately, theproposed preparation advantages (a renewable raw material source and a no-foam sac-rificing structurer) are counterbalanced by the disadvantage of a costly synthesis of n-alkyl lactobionamides (obtained by reacting lactobiono-1.5-lactone with various alky-lamines in anhydrous DMF, methanol, or net a lower yield). The choice of surfactantsand their proportions not only determines the cleaning and lathering characteristics butalso influences mushiness, plasticity, and skin compatibility.

Formulations

European and Israeli formulations are based mostly on a blend of alkyl sulfates andalkyl sulfosuccinates, reaching about 4050% surfactant content. The pH of the baris normally adjusted between 5.5 and 7.0. It has been found that the potassium saltsgive much better mushing and plasticity properties than the sodium salts, and thereis an optimal KNa ratio to minimize mushiness (35).

The U.S. mass-marketed brands are based on other surfactants. They also fol-lowed the soapsyndet concept already patented in the 1940s (soap + LABS +starch) (36), followed by nonsmearing bar formulations based on alkyl glycerylether sulfonate, sodium/magnesium soaps, and binder (37). The leader, Dove, isbased on fatty acid isethionates, specifically SCI. Since this is an expensive ingre-dient, the formulation includes about 2527% fatty acid (specifically stearic acidand a minor proportion of coconut acid) and fatty acid soap, mostly neutralized toa final pH of 7.27.5 (46). The fatty acid presence due to the reaction equilibriumshifting, produces an overall best-performing package, brightly presented as con-taining 25% moisturizing cream. The product contains some dodecyl benzene sul-fonate (12%) as a lather enhancer. This surfactant blend reduces the final cost ofthe formulation but, due to the price of cocoyl isethionate, it is still relativelyexpensive. SCI bar formulations presented by Ho Tan Tai (61) according toUnilever patents (62,63) list a broad range of SCI content of 4460% and a highelectrolyte content of 5% sodium sulfate. The U.S. Dove formulations of the1990sand the 2003 European formulations are presented in Table 5.6.

Since the mildness concept has been strongly advertised by Lever Brothers asan intrinsic property of isethionate bars, a serious change has occurred in bar for-mulation in Western Europe in the past few years. Products have been reformulat-ed; more expensive isethionate bars, claiming even milder properties, have beenintroduced. This has changed the surfactant base from alkyl sulfate/disodium laurylsulfosuccinate (DSLSS) to SCI/DSLSS base. A typical formulation of Sebamed(Germany) from the late 1990s contained about 2530% SCI, 1015% DSLSS,and a blend of fatty acids (C12C18) and mineral oils of about 3035%. Similartrends were followed by European syndet base suppliers (35,46).


The drawback of the cocoyl isethionate bar (easily perceived by consumers)lies in its strong, characteristic odor. This odor recalls the coconut source of thefatty acid and needs a higher dosage of fragrance to be covered. It also creates aproblem in the fragrance-free hypoallergenic formulations. An interesting contri-bution concerning this has been reported recently (64,65). The object of these con-tributions is to deliver a bar with reduced off-odor and a formulation that is mild toskin and easy to process. These objectives are achieved by using a cleansing barcomprising 1070% of a sodium-distilled, topped cocoyl isethionate (STCI). TheSTCI of this invention contains little or no (04%) highly soluble acyl groups (C6+ C9 + C10 + C18:1 + C18:2), about 4565% C12, and about 3055% C14, C16, andC18. The lack of the more volatile shorter chain odorous hydrophobics, as well asthe unsaturated C18 chains are obviously the reason for reduced bar odors. It wasalso claimed that the STCI formulation allowed the use of higher levels of hygro-scopic lather boosters, such as alkyl glyceryl ether sulfonate (AGS), withoutexhibiting processing drawbacks that would otherwise be experienced with regularSCI. STCI usage also allows the addition of larger amounts of water or liquidingredients, such as glycerine and vegetable oils (64,65).

However the significant relevance of these patents (65) to the subject lies inthe inclusion of a broad range of functional ingredients that influence soap, combo,and syndet bar properties, such as off-odors, processability, stickiness, brittleness,mushiness, lather quality, and their combinations. The patents become an explicitformulation showcase, that is worth presenting in depth, that allows a close practi-cal insight into the ingredientperformance relationship (Table 5.7). The STCI barsproduced with the process are comprised of three key ingredients: STCI, a plasti-cizing agent, and a binder, in addition to a mild surfactant matrix (Table 5.7)(64,65). Each will be discussed further.

Other major surfactants used in U.S. formulations are sodium cocoglycerylether sulfonate contained in Procter & Gambles (P&G) Zest combo bar and in Oilof Olay (recently changed to Olay) and the new Ivory Moisture Care syndet bars.These last two products also contain SCI.

TABLE 5.6Dove Bar Formulations (%)

Ingredient 1992 (USA) 2003 (Europe)

Sodium cocoyl isethionate (SCI) 4749 4749FFA (stearic acid + coconut acid) 2325 2325 Soap 710 1013Sodium isethionate 46 46Alkylbenzene sulfonate (LABS) 12 Cocamidopropyl betaine 12Sodium chloride 0.5 0.51 Water 46 56


In Japan, acyl glutamate is the basic surfactant in Mignon, an expensivesoapless cleansing bar. Classical formulations of high pH (910) combo bars, likeLever 2000 and Zest are described in Table 5.8.

Several suppliers offer the main surfactant raw materials to formulate syndetand combo bars, as well as fully formulated ready-to-use soap-free or combo bases

TABLE 5.7STCI Bar Composition (EP 0728186)

FullComponents range Preferred Preferred Function

STCI 1070 1560 2050 The key to the present invention. It ismade from topped distilled coconutfatty acid.

Na-alkyl glyceryl 050 530 1020 Included as a lather-boosting syntheticether sulphonate surfactant. It is made from coconut

fatty alcohols. Equivalent syntheticsurfactants can be used.

Na-alkyl ether 010 18 26 A mild lather-boosting syntheticsulfate surfactant.

Na-cetearyl sulfate 040 430 820 A non-soil load filler and processing aid.Na-soap 020 115 212 A lather booster and processing aid.Mg-soap 050 430 820 A non-soil load filler and processing aid.Fatty acid 035 325 520 A plasticizer.Paraffin 030 325 520 A plasticizer.NaCl 05 0.13 0.22 Provides bar firmness and improves bar

smear.Na2SO4 05 0.13 0.22 Provides bar firmness and improves bar

smear.Na-isethionate 015 110 28 Provides bar firmness and improves bar

smear.Water 320 415 510 A binder.Fragrance 02 0.51.5 0.81.2 A binder and improves odor.

Abbreviation: Sodium topped cocoyl isethionate (STCI).

TABLE 5.8 Combo Bar Formulations

Ingredient Zest (%) Lever 2000 (%)

Sodium glyceryl ether sulfonate 1218 Sodium cocoyl isethionate 1020FFA 610 60Soap (tallow/coconut) 5060 5060 Sodium isethionate 68Magnesium soap 510 Water 58 810Additives q.s. 100 q.s. 100


for bar manufacturing (Table 5.9). Recently P&G began to supply alkyl glycerylsulfonate (AGS) which has been promoted proudly as A Great Surfactant and cur-rently labeled as sodium cocoglyceryl ether sulfonate (6870). AGS 1214 is pre-sented as a surfactant polymer mixture comprising (on a dry basis) 72% AGSmonomer (Table 5.1) and 13% AGS dimer, composed of 11% disulfonate,1%chlorosulfonate, and 1% hydroxysulfonate. The balance contains other molecules,such as 3% unreacted alcohol, 6% glyceryl ether (diol), 3% sodium sulfate, and 3%sodium chloride, which influence the overall properties of AGS (6870). The prod-uct is available as a paste (47% active) or in flakes (75% active). AGS is producedby reacting fatty alcohol with epichlorhydrin, followed by a reaction in a caustic

TABLE 5.9 Commercial Syndet Raw Materials and Ready to Use Bases

Company Base material trade name Base material type

Ajinomoto Inc. Amisoft CS-11, LS-11 Acyl glutamateAkzo Nobel Elfan AT 84 SCIa

BASF Corporation Jordapon Ci Prill SCIa

Jordapon SB II Syndet Base SCIa + SSFinetex Inc. Tauranol I-78-C SCIa

Tauranol I-85-T SCIa

Syndet Base 96-143-1 SCIa

Hampshire Chemical Corp. Hamposyl Acyl sarcosinateClariant Hostapon SCI 65 SCIa

Hostapon SCI 85Neca ChemicalsAgis Group Necadol S-7 SPCS

Necadol S-7 MC SPCS + DSLSSb

Necadol ISK SCIa + DSLSSb

Necadol CBI SK SCIa + DSLSSb + SoapProcter & Gamble AGS 1214 AGS

Zest Flakes AGSRhodia Geropon AS-200 SCIa

Geropon SDT SCIa + SoapTensa Chem Tensianol 815 SPLS + DSLSSb

Tensianol SF SPLS + DSLSSb

Tensianol 3456 B SCIa + DSLSSb

Tensianol 3713 DSLSSb + SCIa

Zschimmer & Schwarz Zetesap 813A DSLSSb + SCSZetesap 5165 DSLSSb + SCIa

Zetesap 5213 DSLSSb + SCAaSCI raw materials contains free fatty acids (stearic and coconut) in proportions of 510% for 85% SCI and 2030% for 65% SCI, and free sodium isethionate between 24%.bSLS and DSLSS are currently supplied as commodities at 3095% concentrations by several suppliers includ-ing those listed above (Table 5.9).Abbreviations: Sodium/potassium lauryl sulfate, SPLS; Sodium/potassium coco sulfate, SPCS; Sodium coco sul-fate, SCS; Sodium cocoyl isethionate, SCI; Disodium lauryl sulfosuccinate, DSLSS; Sodium lauryl sulfoacetate,SCA; Sodium lauroyl sarcosinate, SS; Alkyl glyceryl (ether) sulfonate, AGS; and sodium lauryl sulfate, SLS.


solution to produce an intermediate; this is further reacted with a sulfite mixtureand finally oxidized and pH trimmed to produce the AGS paste (6870). A typicalcombi-bar formulation using AGS is provided by P&G. The formula includes 52%sodium soap, 17% AGS, 14% Magnesium soap, 8% water, 3% salt, and 2% super-fatting agents. Ready-to-use Zest flakes of similar formulation are also offered(6870). Valuable support is given by most raw material suppliers in providingsuggested formulations for optimal performance, and by the syndet-based suppliersto overcome processing problems.

Clariant has done extensive development work to promote Hostapon SCI use incombo and syndet bars (66). The grittiness, a characteristic problem of SCI bars,was researched and relevant parameters to be mastered were considered. This crystal-lization phenomenon, that sometimes occurs under storage, was found to be influ-enced by the way the soap is made. Higher mixing temperature, longer and moreintensive mixing, fluid (water, etc.) presence, and additional milling have been recom-mended. The crystal size distribution of the SCI material is also an important factormastered by the supplier. It is recommended that a grittiness assessment be doneimmediately and at 4 weeks and 3 months after production (66).

Due to the high mixing temperature (100150C) and the high moisture level(1018%), SCI is susceptible to hydrolysis. The electrolyte level was found to havesome effect upon limiting the amount of SCI lost through hydrolysis (66,67).

Cleansing Efficiency

An interesting evaluation of the cleansing effect of various bars indicates that alkylsulfate/sulfosuccinate blends have higher cleansing power, when compared to acylglutamate and triethanolamine soaps, as presented in Figure 5.7 (38). The acylisethionates were not tested for in Weber (38). The cleaning activity was deter-mined with a skin-washing machine that cleans the artificially stained skin of theforearm under standard conditions (39).

By another proposed evaluation method, a fat-based ointment that simulateddirt, was placed on the dorsum of the hand and washed in a rotating soap solutionfor 5 minutes. The cleansing efficiency of various soaps was assessed by compar-ing sebumeter reading before and after the washing (40). Better results, as shownin Figure 5.8, have been found for alkyl sulfatebased bar soap compared to lead-ing isethionate brand, specifically 81% vs. 75% cleansing capacity; water gaveabout 30%. Deposition profiles checked in P&G patents and unpublished/commer-cial publications (87,88) also evaluate rinsing/cleansing efficiency.

AGS was found to rinse cleaner and deposit less compared to SCI, while sodi-um soaps were found to have a much poorer cleaning efficiency (6870). This dataemphasizes again the high surfactant tolerance to hard water given by the highersolubility of Magnesium AGS and Calcium AGS compared to Sodium AGS; thisresults in AGS that rinses cleaner and deposits less. The rinsing efficiency anddeposition profile of several surfactants is shown in Figure 5.9 (6870).


Fig. 5.7. Skin cleansing efficiency of four different cleansing products. Source: Weber (38).

15.0

13.5

12.0

10.5

9.0

7.5

6.0

4.5

3.0

1.5

0.0I II III IV

Disease

Cle

anin

g a

ctiv

ity

n = 41

Sebamed*

Minon*

Neutrogena

Lux

*Soapless Soaps

I. Psoriasis (n = 8)II. Atopic Dermatitis

(n = 5)III. Control with Skin

Diseases (n = 16)IV. Normal Control

(n = 12)


Foaming/Lathering

The foaming properties of different surfactants and finished syndet formulationscan be checked by several methods whose description is beyond the scope of thischapter. A common and reliable test to check foam volume and height is themechanical inversion test. When checked in hard water (320 ppm CaCO3) a higherfoam performance was found for alkyl sulfate and sulfosuccinate formulationscompared to isethionate-based syndet/combo bars and natural soap (41) (Fig.5.10). However, this test doesnt give any information on the foam quality, as amore bubbly foam gives more volume than a dense creamy foam, the latter beingbetter appreciated for moisturizing formulations. Even the classic Ross-Miles

Fig. 5.9. Rinsing efficiency and deposition profile of different surfactants.

Cle

anin

g ac

tivity

(%

)

Fig. 5.8. Skin cleansing efficiency of two different cleansing products compared to water.Source: Wolf and Friedman (40).

Deposits measured in g/20 cm2/product (%)

PRODUCTS: Neca7 Leading soap with Water25% moisturizing cream


method (42) is still being used in recent patents (28); for instance, an initial foamheight of 153 mm, collapsing to 5 mm after 10 min was found for C12 lactobion-amide compared to an initial height of 145 mm that stays stable at 140 mm after 10min for C14 lactobionamide. It is evident that the sensitivity of foam stability mea-surements depends on the hydrophobic chain.

Expert-rated panel-lathering tests are seldom preferred (6), reporting especial-ly on speed of formation, quality of foam, and lather feel during washing. Lathervolume is also practically determined by accumulating the lather generated byrotating a bar ten times with a wetted glove under a stream of water at a given tem-perature (28). Some results from the German DIN 53902 method are reported forethoxylated isostearyl monoglyceride added to the syndet solution; they reducedfoam from 500 mm to 150 mm (21). Hydrophobic additives, selected for theiremollient or plasticizing contribution, reduce foam considerably.

To enhance the lather performance of the primary surfactant in lather formationspeed, stability, or cold water performance, some foam enhancers can be used.Dodecyl benzene sulfonate, sodium lauryl sulfate, alkanolamides, and even neutralizedfatty acids perform this function well. Alkyl polyglucosides (APG) have been promot-ed recently by Cognis (71) and Seppic (72) as foam enhancers, especially in soap for-mulations containing 1.21.5% Plantaren/Plantacare (71) or Oramix (72). Both com-panies suggest that the same result was perceivable in syndet/combo formulations.Cognis reports on SCI:soap combo (ratios 50:8 to 70:8 on 100% active basis) with89% APG showing improved processability and lathering as compared to the non-

Fig. 5.10. Foam/lather performance. Water hardness, 320 ppm CaCO3; Water temper-ature, 30C; Product concentration, 0.16 wt%.

Foa

m/la

ther

vol

ume,

mL


APG original base; 15% APG is also recommended as a co-surfactant in a syndetbased on 40% DSLSS and 15% paraffin wax as a lipid-layer enhancer.

Plasticizers and Binders

To obtain good processability and usage properties, the formulation is stabilizedwith plasticizers and binders. Plasticizers are included to facilitate better extrusionand stamping of the syndet bar. The plasticizers act by lowering the viscosity ofthe material at the manufacturing temperature, providing flow under pressure.

Binders prevent separation of macroscopic aggregates, caused by local stress,and provide cohesion and anticracking behavior of the solid product. Natural soapdoes not have plasticity problems, as the soap itself is a classic plasticizer, beyondits cleansing surfactant role. Plasticizers and binders strongly influence lathering,mushing, and wear characteristics. Generally, the plasticizers and binders are usedtogether, and one material can perform at least two roles. They are able to absorbsome or all of the free water of the syndet, bind the various ingredients together,plasticize the mass, and act as emollient simultaneously. The plasticizers mostcommonly used are long-chain fatty alcohols (higher than C16), polyol esters (glyc-erol monostearate, sorbitan stearate, and glycerol mono- and distearate), polyethyl-ene glycol, sodium stearate, stearic acid, fatty acid ethoxylate, hydrogenated castoroil, paraffin wax, fatty alkyl ketones, and a combination of hydrogenated triglyc-erides with fatty alcohols or acids (21,41).

As pointed out in Table 5.7 (64,65), at least 20% plasticizers are used; theseare comprised of fatty acids and paraffins that are solid at room temperature but aremalleable at bar-plodding process temperatures of about 3545C. The binder usedin the same patent is any material that is by itself liquid, and is selected from water,liquid polyols, and even fragrance. Their levels in the bar are theoretically 320%water and 015% polyols (64,65).

The plasticizers and binders have high melting points and high molecularweights. It seems that their binding activity is obtained when the melting point ofthe mass is simply raised. Ingredients, such as gums and gum resins, provide addi-tional cohesion by acting as binders.

Some patents (20) describe the binder as stucturer, specifically referring topolyalkylene glycol (2560%). Recent patents (2426) define special binding asformation of a rigid crystalline phase skeleton structure, comprising an interlock-ing, open three-dimensional mesh of elongated crystals. The crystals in this case,essentially consist of 550% (24,26) or 1050% (25) fatty acids, of which 2065%are neutralized, in addition to 1565% (26) or 2065% (24,25) of anionic and/ornonionic bar firmness aid, including a relatively high water content of 1555%(25) or 1540% (24,26). The surprising aspect of this invention is that bar hardnessand low smear are obtained in the presence of soft hydrophobic materials (includ-ing petrolatum, paraffins, and most natural and synthetic waxes) non-ionic solvents/co-solvents (propylene glycol, glycerine, etc.), and anionic surfactants that typical-


ly result in bar softening. This results in the interlocking crystalline skeleton net-work that contains substantial void areas being filled by soft and/or liquid aque-ous phases; this drastically changes the colloidal structure, and consequently, thephysical properties of a conventional bar. The only disadvantage of this almostideal bar is that it is not extrudable under normal working conditions, and itspreparation is made by pouring the molten mixture into a bar-shaped mold (24,25)or by a freezer process in which the molten mixture is cooled to a semisolid in ascraped wall heat exchanger and then extruded as a soft plug, cooled and crystal-lized, fed on a moving belt (26). Worth mentioning are several patents (33,34)proposing solid shampoo formulations that are processed in a molded form, basi-cally formulated with alkyl sulfates.

Cast (Poured) Transparent/Translucent Syndet/ComboCleansing Bars

The ultimate challenge of the syndet/combo market is to create an extrudable trans-parent/translucent of a neutral pH. Technically this target has not yet beenachieved but in the meantime the market segment of cast (also called poured,molded) transparent combars is steadily increasing. Beside the concept of purityand aesthetic appeal, this target provides a way to produce milder formulationswith enhanced skin properties. With regular extrusion techniques, both soap andsyndet bars have limitations to the amount of additives that can be used. These lim-itations can be overcome by using the castpouring techniques, while maintainingonly a minimum degree of stickiness and mushiness. The special bar bindingthrough formation of a crystalline skeleton network (2426) seems to give therequired bar hardness and low smear for a pourable transparent combar containingSLS, SLES, SCI, and CAB (cocamidopropylbetaine) together with fatty acids,PEG, paraffin wax, and silicones (74).

Several commercial combo bases are offered on the market by different suppli-ers, such as Stephenson, Galaxy, Tensachem, and Unichema. Crystal ST fromStephenson is a hot-pour base containing sodium stearate/stearic acid, sodium lau-rate/lauric acid, and SLS/SLES surfactant mixture besides a glycerine/propylene gly-col/sorbitol clear matrix (73). The Galaxy SN-900 series used in transparent combobody wash bars contain 2540% soap, 2535% glycols, 1015% anionics (SLES)and amphoterics (CAB), 1015% sugars, and 1015% moisture (75). A recent patent(76) claims a transparent bar using a synthetic detergent and a soap having anenhanced transparency, clarity, and mildness not achieved previously. The composi-tion is composed of the following: 4045% surfactant (of which 1535% is an SLEStype); 1030% of a polyhydric alcohol (such as propylene glycol, glycerol, sorbitol,or PEG); 1530% soap; and 520% alkanolamide as a foam stabilizer. A preferredpH of 9.6 and not below 8.0 (because of loss of clarity and hardness) is claimed.Surprisingly, the claimed product has mildness equal to Dove as checked by a modi-fied soap chamber test even at this relatively high pH (48,76).


Transparent and translucent combo bar formulations have been commercially pro-moted by adding nonoxynol-10-carboxylic acid and C1215 alkyl benzoate to the soap-syndet base (57). Commercial offerings of cleansing bars based on sarcosinates (43) oracyl glutamates (even of translucent appearance) (44) have been made during the lastfew years, in spite of the industrially inefficient hot-pour manufacturing method used.

A beautiful, round-shaped acyl glutamate syndet has recently been launchedby Ajinomoto in a KoreanJapanese venture that is being promoted abroad (77).This is a so-called gel-soap called Amino Crystal, emphasizing the main aminosurfactant, TEA cocoyl glutamate; additional components are decyl glucoside,hydrolyzed collagen, dipotassium glycyrrhizinate, glycerine, urea, and isopropylalcohol. Two factors are especially striking: the pH is about 6 (which is quite rarefor a totally transparent syndet), and the price. The soap is supplied at about $16per 100 g piece (FOB Japan) with a recommended consumer retail price of $100per piece! Who said that the soap business is not a profitable one?

Performance- and Appearance-Improving Additives

One perceptible drawback of the syndets is their solubility and mushiness in water,which is known as bar smear or bar slough. This messy, unattractive and uneco-nomical property is due to the high solubility of some surfactants and inappropriateformulation. Under certain formulations, this paste-like mush is unable to return toa solid state by losing water from the mush layer. Using higher water levels in theformulation will result in the wanted manageable neat phase (also known as the Gor lamellar phase) transforming into a viscous jelly-like middle phase. One majorsolution used for alkyl sulfate syndets is to use their potassium salts, which gives alow mushiness and an economical base.

Other low-solubility enhancers are inorganic salts, such as sodium sulfate andsodium chloride. A recently patented process produces a soap and combo bar with0.510% auxiliary mild surfactants (78); these bars have enhanced skin-care proper-ties from the addition of protic acid salts (PAS) to soap formulations with fatty acidsoaps, free fatty acids (FFA), and polyalkylene glycols. A protic acid is any acid thatreadily yields protons, for example, a Brnsted acid. The salts of such protic acids areselected from inorganic and organic acids, with preference being given to sodiumchloride/sodium sulfate for the inorganic, and sodium lactate/sodium citrate for theorganic. The required ratio FFA:PAS of 0.5:1 to 3:1 is highly emphasized (78).

Aluminum triformate efficiently reduces water solubility in sulfosuccinate for-mulations (21). Slipping has been obtained by adding zinc stearate (recently reap-pearing in the ingredient list of Extra Sensitive Dove brand, marketed in Europe)and ethoxylated sorbitan ester (10,21). Preferred slipping agents are high molecularweight ethylene oxide polymers (such as PEG 14M) (78). Sodium isethionate isadded in acyl isethionate formulations to reduce wear rate (37).

Bar appearance (water retention and/or shrinkage prevention) aids are seldomselected from a long list of water-soluble organics, salts, clays, and suitable waxes


(preferably paraffin) to impart skin mildness, plasticity, firmness, processability,glossy look, and smooth feel to the bar (2426). Antibacterial additives, such astrichlorocarbanilide and triclosan, are good examples of successful additives fordeodorant and antibacterial bars, even if their use is currently being questioned.

Fillers

The fillers are, by definition, cheaper ingredients, used to reduce the bar cost. Inthe case of syndets, the fillers are not inert ingredients but participate in improvingthe internal structure and hardness of the finished product. Fillers can therefore becalled additional binders. The best-known fillers are dextrin, starch, and modifiedstarch (degraded, ethoxylated).

Talcum powder has also been used as a filler to aid against mushiness, whilebuffered borax is added to reduce specific gravity and lower wear. The drawbacksof the fillers are a rough surface texture, loss of slip, and loss of attractive overallappearance. For this reason, one should not exceed an optimal concentration ofthese substances. Recently Luzenac (79) promoted new talc grades presented asinnovative technology and applications for soaps and syndets (79,80).

The list of fillers quoted by Hollstein and Spitz (21) also notes sodium sulfate,CaHPO4, MgHPO4, NaH2PO4, dextrin, and mannitol as being state-of-the artexamples. A current state-of-the-art list will include calcium carbonate and talcum(140%), aluminosilicate clays and/or other clays (0.525%), and salt and salthydrates (140%) of almost any existing cations and anions (2426). Sometimeswheat flour is preferred to cornstarch since it imparts a more acceptable wear rateto an acyl isethionate bar, which can contain between 25 to 65% filler (45).

Mildness Improvers/Skin Conditioners/Moisturizers

The formulation of a mild or even ultra mild soapsynbar has become a top focusin the field; a great deal of research and development was devoted to make soapsmilder. Moisturizers, emollients, and superfatting additives were included to pro-vide skin conditioning benefits and to improve mildness. Most of them are present-ed in Table 5.10 (29,53). The superfatting term comes from fats and oils foundin the soap boil in excess of stoichiometric needs. As in conventional soaps, thesuperfatting additives promote in the syndet/combo bars a denser, creamier lather,that leaves the skin smoother and softer. Classical superfatting agents that wereused in alkali soaps, such as palm and olive oil (Palmolive), mineral oil (GentleTouch), cocoa butter (Tone), and fatty acids (Coast/Shield), are also of practicaluse in syndet/combos (16). The addition of these additives has a plasticizing effecton the base, so that moisture content usually needs to be lowered and the hardeningagent content (such as salt) has to be increased.

Patented skin conditioning/mildness aid agents seldom listed are hydratedcationic polymers selected from a broad range of cationic polysaccharides, cation-


ic co-polymers of saccharides, and synthetic cationic monomers of syntheticnitrogen polymers (28,30). A preferred polymer is a hydrated cationic guar gumhaving a molecular weight range of 2,500350,000. Incorporating 1% cationicguar gum (such as Jaguar C-14-S) to soap/syndet (about 67% soap) formulation isreported to reduce erythema/dryness score below that of a Dove type formulation,when checked by in vivo forearm test (28). A new version of Dove, launched in1995, unscented and recommended for sensitive skin, contains cocamidopropylbetaine that was seldom included in European formulations for its synergisticimprovement of anionic surfactant mildness. Since then, betaine became the pre-ferred foaming mild co-surfactant and replaced the harsher DDBS in all the newversions of Dove.

Some 2 in 1 soap and cream concepts have been solved not by soapless formula-tions but by including skin mildness and moisturizing additives with mild surfactants.Examples are FA 2 in 1 Soap and Cream with sodium myreth sulfate, decyl glucoside,sodium laureth sulfate, sodium lactate; Monsavon 2 in 1, Savon et Creme with 25%base hydratante, containing ceteareth 80, glycerine, guar hydroxypropyl trimoniumchloride; and Palmolive 2 in 1 Wash & Creme with disodium lauryl sulfosuccinate,coconut acid, stearic acid, and lanolin.

A comprehensive ingredient list of the most well-known syndet and combobars is given in Table 5.11. The ingredient lists for most formulations have beenupdated to the 2003 formulation list. Table 5.11 demonstrates the dynamic naturethat formulas must possess to be able to cope with the market, consumer, environ-mental, and regulatory changes, while providing formulation improvements.Striking differences are sometimes found for the same multinational brand manu-factured in different parts of the world. For instance U.S. Zest is based on sodiumglyceryl ether sulfonate (SGCS), while Zest Mexico contains potassium lauryl sul-fate instead (Table 5.11).

TABLE 5.10 Moisturizers/Emollients in Soapsyndet Bars

Moisturizer Type Purpose Type of Raw Material

Occlusive Deposit on skin surface, Long-chain fatty acids (25% moisture cream), reducing rate of evaporation cream), mineral oil, ethoxylated/propoxylated

ethers of lanolin alcohol or methyl glucose,vegetable oils.

Non-occlusive: Hygroscopic substances to Glycerine, propylene glycol, polyols, sorbitol,stratum corneum, retaining lactic acid, pyrolydone, carboxylic acid, urea,water, improving lubricity L-proline, guanidine, pyrolydone, hexadecyl,

myristyl, isodecyl, isopropyl esters of adipic,lactic, oleic, stearic, isostearic, myristic orlinoleic acids, isotearyl 2-lactylate, sodiumcapryl lactate, proteins, aloe vera gel,acetamide mea.


TABLE 5.11.a Syndet/Combar Compositions (from Ingredient Labels)

VELa Dove Exfoliatingb Dove Nutriumb Caressb Doveb

SCI SCI SCI SCI SCI Stearic acid Stearic acid Stearic acid Stearic acid Stearic acidSodium tallowate Sodium tallowate Sodium tallowate Coconut acid Sodium tallowateWater Coconut acid Water Sodium tallowate Aqua (Water)Coconut acid Sodium isethionate Sodium isethionate Water Sodium isethionateSodium isethionate Water Coconut acid Sodium isethionate Coconut acidSC/SPK Sodium stearate Sodium stearate Glycine soja oil Sodium stearateHCO CAB CAB Sodium stearate CAB Fragrance SC/SPK Sunflower Seed oil CAB ParfumTitanium dioxide Fragrance SC/SPK Mica SPK Glycerine Sunflower seed oil Fragrance SC/SPK Sodium chlorideSodium chloride Tocopheryl acetate Lanolin alcohol Fragrance Trisodium EDTA PSP Sodium chloride Tocopheryl acetate Sodium chloride Zinc stearate

Polyethylene Glycerine Tetrasodium EDTA TSE Tetrasodium EDTA Sodium chloride TSE TSE Titanium dioxide BHTTitanium dioxide Tetrasodium EDTA Titanium dioxide

TSEBHT


TABLE 5.11.b

Cataphilc Zest Mexicod Zestd Lever 2000b Olayd

SCI Sodium tallowate Sodium tallowate Sodium tallowate SCI Stearic acid Magnesium tallowate SCGS SCI ParaffinSodium tallowate PLS SC/SPK Sodium cocoate/laurate SCGS Water Sodium cocoate Magnesium cocoate Water GlycerineSodium stearate Water Water Sodium isethionate WaterDDBS Talc Magnesium tallowate Stearic acid Magnesium silicateSodium cocoate Sodium sulfate Talc Coconut/lauric acid Magnesium stearatePEG-20 SLES Sodium chloride Fragrance Sodium isethionateSodium chloride Magnesium cocoate Triclocarban Sunflower seed oil Stearic acidFragrance Fragrance CA/PKA Tocopheryl acetate Magnesium cocoateSodium isethionate Sodium chloride Fragrance WGAPD Coconut acidPetrolatum Titanium dioxide Titanium dioxide Hydrolized wheat protein Sodium stearateSIL Citric acid Tallow acid Titanium dioxide Sodium cocoateSucrose laurate Sodium citrate PSP Sodium chloride FragranceTitanium dioxide PSP TSE Disodium phosphate Magnesium lauratePSP Tetrasodium EDTA Titanium dioxideTSE TSE Lauric acid

BHT Sodium laurateTetrasodium EDTATSE PEG-90M


TABLE 5.11.c

Eubosee Satinac Lanosanf Nivea Milk Barg Sebamedh

DSLSS SCI Paraffin SCI DSLSSSodium coco-sulfate Glyceryl distearate SCI Stearic acid Triticum vulgareTriticum vulgare PEG-200 DSLSS Sodium tallowate ParaffinCetearyl Alcohol Cornstarch Glyceryl stearate DSLSS SCIParaffin Paraffin Sucrose Sodium cocoate Glyceryl StearateCAB DSLSS Water Coconut acid Stearic acid PEG-CCG Coceth 20 Lauryl polyglucose Paraffin Palmitic acidAqua Petrolatum Milk protein PEG-150 Cetyl PalmitateGlycerine Panthenol CAB Parfum Cetearyl AlcoholAllantoin HAP Citric acid Sodium chloride AquaAluminum formate Bisabolol Stearic acid Tetrasodium EDTA LecithinTitanium dioxide Disodium EDTA Aluminium triformate Sodium etidronate Sodium lactate

Sodium hydroxide PEG-GI Glycerine Tocopheryl acetateFragrance Betaine Lanolin alcohol Glycine

PEG-45 M Magnesium aspartateCetearyl alcohol Mixture (M)i

Fragrance ParfumaColgate-Palmolive; bUnilever; cBayer; dProcter & Gamble; eDr. Holbein; fWella; gBeiersdorf; hSebapharma; iAlanine pyroxidone HCl, lysine, leucine, urea phosphate,polyquarternium 22, disodium EDTA, PEG14 M.Abbreviations: Cocoamidopropyl betaine, CAB; Coconut/palm kernel fatty acid, CA/PKA; Disodium lauryl sulfosuccinate, DSLSS; Hydrolyzed animal protein, HAP;Hydrogenated castor oil, HCO; PEG-6 Caprylic capric glycerides, PEG-CCG; PEG 15 Glyceryl isostearate, PEG-GI; Pentasodium pentetate, PSP; Potassium lauryl sulfate, PLS;Sodium cocoate/sodium palm kernelate, SC/SPK; Sodium cocoyl isethionate, SCI; Sodium cocoglyceryl ether sulfonate, SCGS; Sodium dodecylbenzene sulfonate, DDBS;Sodium isostearoyl lactylate, SIL; Sodium laureth sulfate, SLES; Sodium palm kernelate, SPK; Trisodium etidronate, TSE; Wheat germ amidopropyl dimethylamine, WGAPD.


Mildness Concept

Over the past 25 years many changes in the approach to soaps have occurred. Theturning point was in 1979 when Frosch and Kligman described a new method toassess soap irritant properties (48). They demonstrated that the chief weakness ofthe existing tests was that under normal usage conditions the reactions were weakand did not discriminate between different soaps. They proposed the soap chambertest (SCT) to conduct tests on people known to have sensitive skin under extremeconditions, thus producing strong reactions that emphasize the differences betweenvarious soaps (48). After five weekday Duhring chamber exposures to 8% soapsolutions (24 hour application in the first day, 6 hour applications in subsequentdays), the skin reaction (erythema, scaling, and fissures) are read and rated, thatcharacterize a soap as mild and non-irritant when the total score is less than 1 andharsh when it is close to 5, the maximum score.

Tests performed in Israel in 1992 confirmed Dove mildness, producing similarresults for Neca 7 syndet with 25% moisturizing cream and Soft with 25% mois-turizing cream (Fig. 5.11). The two local brands were based on SCI/DSLSS soap-free syndet blends. However, similar tests made in the U.K. during the winter of1993 scored Lever 2000, considered to be mild, around 2.0, while Neca 7 and Softscored 0.9 and 1.6, respectively (Internal Neca Publication, unpublished). The totaloverall mean score was primarily due to the erythema results, while the scaling andfissuring values were lower than 0.2 for all the products.

Climate conditions and skin panel sensitivity greatly influence the results, asalready found and reported by Frosch and Kligman (48). Similar large variations inthe SCT mildness scores for Dove over the course of a year have been reported,showing values from 1.05 to as high as 2.65 (78). Thus whenever certain bars wereevaluated, the mildness of both Dove and Ivory (used as a control for a so-calledirritant product) were also evaluated (78).

Irrit

atio

n sc

ore

Test

Fig. 5.11. Soap chamber test of 0.06 mL (8% w/v), overall mean score.


The lack of correlation that sometimes exists between consumer tester reports andthe proposed Frosch and Kligman toxicity ladder is intriguing. Consumer surveyreports from 500 women who took part in usage tests showed that the best-liked soapwas Neutrogena Normal to Dry, which ranked first in all categories, including luxuri-ous skin feel, quick rinsing, super cream feeling, and produced extra skin softness(49,50). Dove ranked much lower. The results contradicted the soap chamber test inwhich Dove was the leader and Neutrogena ranked seventh (48). Similar discrepan-cies between facial wash and SCT results have been reported by Frosch (52). Thequestion then arises: What test actually reflects soaps quality most accuratelytheirritancy tests under extreme conditions, or a broad survey of consumers? A not lessimportant question is: What is the most important property of a soapmildness, orcleansing power and feeling of the skin after use? (50).

A comprehensive survey of the models for surfactantskin interactions that detailthe mildness from in vivo and in vitro evaluation methods was compiled by Paye (81)and is summarized in Table 5.12. As can be seen, the extreme usage conditions of SCTare obvious when compared to other in vivo tests that are normally used in state-of-the-art patents and performed under realistic rinse-off usage conditions (application timenot exceeding 90 seconds, compared to at least 6 hours in the SCT). For this reason the

TABLE 5.12Mildness Evaluation Methods

Type of test Method Reference

in vivo Flex wash test (3 washes daily, total 15 washes) 17,29(60 sec application)

Arm wash test (4 washes daily, total 40 washes) 29(90 sec application) evaluate smoothness, erythema, and dryness

Forearm wash test (4 washes daily, total 17 washes) 29,17(90 sec application) evaluate erythema, and dryness)

Soap chamber test (5 d, 24 h and 6 h 4 applications) 48evaluate erythema, scaling, and fissures

in vitro Skin barrier destruction test 17,18,23,Skin barrier destruction is measured by the relative 2527,54,55

amount of radio labeled water (3HH2O) which passes from the test solution through a skin epidermis membrane into the physiological buffer contained in the diffusive chamber

Zein testThe Zein protein (similar to keratin) is solubilized in a

surfactant solution. The Zein solubilized is determined by the released nitrogen content. The Zein number is measured as mg N/g surfactant.

Red blood cell (RBC) testHemoglobin denaturation or haemolysis test; measured by

visual examination, transepidermial water loss (TEWL), or blood flow


SCT method has been largely replaced in the industry by other in vivo tests, such as theforearm-controlled application techniques. This methodology was also selected for arecent Unilever patent (78) that used controlled application wash tests, such as the Flexwash and Arm wash tests to quantify the relative potential to induce irritation, skinbarrier damage, and dryness. These tests utilize a combination of subjective evalua-tions (visual skin condition assessment by expert graders) as well as objective instru-mental biophysical measurements to quantify the induced changes to the skin barrierfunction and the skins ability to retain moisture (78).

Different protein denaturation in vitro tests have been developed to predictsurfactant-induced eye or skin irritation (81). The Zein test is one of the widelyused in vivo screening methods to evaluate local tolerance of surfactants (Table5.12). Zein is a protein obtained from corn and resembles keratin. The Zein testdeveloped by Gotte (82) is based on the solubilization of the corn protein; the pro-tein is normally insoluble in aqueous solutions unless denatured. It is incubatedwith the surfactant solution for 1 hour at constant temperature and under slightshaking. At the end of the incubation, the soluble fraction is separated from theinsoluble one by centrifugation and filtration. As the surfactant-induced irritationincreases, more Zein will be denatured and solubilized.

Zein solubility in a surfactant solution is measured and given as mg nitrogensolubilized per gram of surfactant, known as the Zein Number (mg N/g). Valueslower than 200 classify the product as mild and nonirritating. Zein values of differ-ent surfactants, as measured by Clariant (83), are presented in Figure 5.12.

Combar mildness evaluation by the Zein test has been used in several patents,such as in a Unilever patent (84). They found that a fatty acid soap containing125% polyoxyethylenepolyoxypropylene surfactants (EOPO polymer of ratiobetween 1.2:1 to 15:1 and a MW of 200025000) has enhanced mildness with nosacrifice in processability or lather. The claim was proved by showing that Zeinvalues of combars containing about 34% soap, 14% SCI, 10% fatty acid, and 25%EOPO polymers are lower by 40% when compared to non EOPO bars (84).

The red blood cell (RBC) test also investigates the protein-denaturing effect ofsurfactants by using red blood cells as a biological material substrate (85). The sur-factant solution causes hemolysis of the blood cells and subsequently releaseshemoglobin into solution and partially denatures it. After eliminating intact cellsand cell debris by centrifugation, the amount of released hemoglobin and the pro-portion of denatured hemoglobin are assayed spectrophotometrically. The capacityof the product to induce cell hemolysis is currently used to predict the eye irritationpotential of the material, while the skin irritation potential is predicted from theproportion of pigment which is denatured (81). RBC values of different surfac-tants, based on Clariant results (83,86), are presented in Figure 5.13.

Most of the P&G patents (64,65) measure the surfactant mildness by a skin-barrier destruction (SBD) test, developed by Franz (54). One of the patent claims,based on SBD findings, is that the long-chain alkyl sulfates are milder than AGSand incorporation of 820% sodium cetearyl sulfate contributes to the required


mildness of the specified product (64,65). A surfactant mildness comparison, asmeasured by SBD test, has been also used by P&G to promote the newly commer-cialized AGS surfactant (6870). The results are presented in Figure 5.14.

In Israel one particular neutral soapless soap (Neca) commands about 30% ofthe market. Although it has been on the market for about 40 years and has under-gone many clinical tests throughout that period, it has never lost its place as themost widely sold soap in the country. Testing this soap with the new methods pro-duced confusing results. In SCT, Dove was shown to be much better than the localsoap. In the Zein test, which generally correlates well with the results of the cham-ber test (50,51), the two soaps were equal; both were only moderately irritating(Fig. 5.15). Another low pH soap, Softcare, has proven itself to be a very mildbaby soap in clinical experiments in Israel. It was found to be much superior toDove in the Zein test, 76 vs. 272, respectively, and in the SCT the opposite was thecase (Fig. 5.15). The two local syndet brands are based on an alkyl sulfate/sulfos-uccinate blends of different alkyl sulfate types and alkyl chain lengths as well asvarious AS/DSLSS ratios.

The confusing results presented here raise the question of whether laboratorytesting under extreme conditions is more reliable than clinical testing or consumer

APG C12/14

Alkylamphoacetate

CAB

MgLES + 3EO

Sodium cocoyl isethionate

Ethercarboxylic acid C12/14

SLES + 3EO

Sulfosuccinate

Sodium cocoyl glutamate

Sodium lauroyl glutamate

Sodium methyl cocoyl taurate

SLES + 2EO

Sarcosinate

Sodium alkyl sulfonate

Soap

SLS

LABS

0 100 200 300 400 500 600 700

mg N/100 mL Surfactant

Fig. 5.12. Zein values for various surfactants at 1% active matter.


opinion that reflects decades of use. Should we rely on the sometimes confusingdata that arise from very modern and sophisticated tests or on clinical tests andbroad survey of consumers and usage tests (50)? It seems that the answer can befound in the remark made by Frosch (52) that with regular use the soapless soaps . . .cause no adverse effects in people with normal skin . . . and are often beneficial to peo-ple of oily skins.

The wide acceptability of the mentioned soap is consistent with this remarkof Frosch, since 80% of the population have oily to normal skin and therefore, lab-oratory testing under extreme and unphysiological conditions is irrelevant forthem (50). This statement confirms recent objective self-criticism of Kligman onthe patch test procedure (56). The proposed approach is a syndet bar for each skintype recommending soaps for normal to oily, normal to dry, and for dry and sensi-tive skin. Different formulations and ingredients should suit different skin types.For instance, an alkylsulfate/sulfosuccinate base is suited to normal to oily skin,while an isethionate base is suited to dry and sensitive skin.

0 20 40 60 89 100

Denaturation

Fig. 5.13. RBC values of different surfactants at 1% active matter.

APG C12/14

CAB

Sodium lauroyl glutamate

S Sarcosinate

M MgLES + 3EO

SLES + 3EO

Sodium cocoyl Glutamate

Sodium cocoyl isethionate

Sulfosuccinate

Sodium methyl cocoyl taurate

SLES + 2EO

Sodium alkyl

SLS

LABS

sulfonate


Market Development

Syndet bars have come a long way since their first commercial development about50 years ago. It was then that mild cleansing bars were formulated by German der-matologists for patients who suffered from soap eczema due to sensitive skin. Atthat time, the bar was composed of surfactants similar to those popular and stillwidely used in shampoos. In fact, some soapless soap manufacturers defined theirbars as solid shampoo, promoting a successful marketing approach. However, itis interesting to note that even todays patents (22,33,34) recall this concept, butthey refer to moulded formulations. A similar approach was adopted by the Israelimarket, the only one in which syndet cleansing bars cover over 50% of the totalsoap-bar market. This market share, favored by hard water considerations, is stillgreater than in any other market, although the current American and Europeanmarkets have been growing tremendously.

At the beginning of the 1990s, Germany seemed to be the major Europeansoapless soap cleansing bar market with 6% in soap volume but with 20% of thetotal value market, since syndet bars are much higher priced. The high price of thesyndet bars was due not only to the more expensive formulation than the naturalsoaps, but was also due to the marketing positioning and strategy. Most of the suc-cessful brand names in Germany were positioned on a dermatological platform aspremium-priced, upscale products; focusing on their skin benefits and selling pri-marily through pharmacies and drugstores resulted in a final consumer price of

Sodium laurylsulfate; sodium

cocoate soap

Sodium C14C16olefin sulfonates

Phosphate esters;sodium laureth

sulfate

Sulfosuccinates

Taurates

AGS;isethionates

Amphoterics

Milder Harsher

Fig. 5.14. Surfactant mildness comparison.


$23/100 gm bar. In France, where the soapless soaps are categorized as pain der-matologique, leading brands account for about 2% of the total soap market andare priced similarly to their German counterparts.

Forty years ago, Neca took an entirely different approach in Israel. Neca rec-ognized the mass market potential of a bar having the benefits of a synthetic soapbut selling at a popular price. In 1964 the company introduced Neca 7, a soaplesscleansing bar having a dermatological value similar to the European syndets butpriced at $0.500.70/100 gm bar and marketed as an all-purpose cleansing barthrough all distribution channels. Neca 7 quickly became the leading brand inIsrael and until now has commanded about 30% of the total soap market, surpass-ing the slightly lower market share of another local syndet bar, Hawaii, owned byHenkel. Neca 7 can probably be considered to be the worlds best-selling syndetper capita in the highest syndet market share country in the world.

The same marketing approach has been successfully applied in the U.S. byLever Brothers, which followed the same strategy of mass-market distribution, pric-ing, and promotion for its soapless and combination cleansing bars (especially Doveand, more recently, Lever 2000). In 1955, Dove was introduced as being different

Softcare Neca 7 Dove Neca 7 Lux Sodiumwith 25% lauryl

moisturizing sulfatecream

Zei

n nu

mbe

r, m

gN/g

Fig. 5.15. Zein number for various soaps.


from other toilet bars because it looks like a soap, its used like a soap, but it is not asoap. Later, Lever began emphasizing that Dove contains one quarter moisturizingcream and wont dry your skin like soap, which remains the slogan of the presentadvertising campaigns. After a 1979 successful dermatological promotion supportedby Kligman tests reporting that Dove soap was the best for the skin, Doves marketshare grew. In 1982 Dove began successful marketing to doctors; it increased its mar-ket share constantly until it surpassed 9% by volume in 1990, when unscented Dovewas introduced, while the last original Dove patent expired (87). By 1993, Dove wasthe best seller, accounting for 16.4% of the U.S. bar-soap market.

The success of soapless and combo bars in the United States was so dramaticand sustained, that in 1991 Lever Brothers was able to oust P&G from the leader-ship position in the toilet soap market. Two years later, in 1993, P&G responded inthis soap war, and regained the leadership with the success of its WhitewaterZest and, especially, Oil of Olay cleansing bath bars. The marketing strategy of theOil of Olay bar, a beauty bar at a competitive price, helped P&G regain the topposition by May 1993 with a 32.5% share, compared to 31.5% for Lever Brothers.The key to the P&G success was primarily due to over a decade of research anddevelopment, that enabled the creation of a unique formula, which contains a spe-cially engineered synthetic cleansing system. This again emphasized the impor-tance of a properly chosen formulation for a targeted cost-effective product. Thesewere the years in which biggest jump was made by Oil of Olay, continuing thesyndet and combo revolution, that was followed by Ivory Moisture Care syndetmarket share increase and Zest Hardwater Clear Choice revival.

During the mid-1990s the European market totally surrendered to Dovesinternational penetration, changing prices, formulations, and marketing strategy(58). In 1995 Dove for sensitive skin and Dove body washes made their debuts. In1999 Dove Nutrium skin nourishing bar was launched, visually emphasizing a dualformula (whitepink strips) that contained natural skin needs. The white formulawas advertised as a gentle cleanser, while the pink formula contained a nutrient-enriched lotion with vitamin E (87). Dove advertising for 2002 emphasized sensi-tive skin innovations of unsurpassed mildness comparing a relatively high erythe-ma score (1.9) of Cetaphil gentle cleansing bar with Dove Sensitive score that wasonly 1.4 (88). The same advertising highlighted the proven compatibility for med-icated applications containing Retin A and benzoyl peroxide (88). Dove GentleExfoliating Beauty bar was launched in 2003 and formulated with small, soft,smooth blue beads, that combined the brands moisturizers with gentle exfoliation(89). During the last few years, P&G has been active too, focusing more on theemotional needs of consumers and launching a variety of new invigorating, freshand wild scents for Zest (89).

During the last few years, bar soap sales dropped and liquid-cleansing prod-ucts increased significantly. The marketing titles of 2000, such as liquids move upin the soap market already emphasized in 1999/2000 an annual increase of 7.7%in liquid soap sales, increasing to $900 million. At the same time the bar soaps


sales fell 4% to $1.4 billion according to Information Resources Inc., Chicago(IRI) (98). Recent data from IRI for the year ending August 2002 showed that U.S.sales of non-deodorant bars fell 3.9% to $447 million and deodorant bars dropped5.4% to $441 million, while liquid soap rose 4.6% $288 million. The sales werecalculated for food, drug, and mass merchandisers (excluding Wal-Mart) (90). Thelatest data from ACNielsen (Chicago) showed that the sales of personal soaps andbath care items in the 52 weeks ending Aug. 9, 2003 sank from $1.9 billion to $1.8billion, shifting focus from traditional soaps to multipurpose cleaners, liquids, andbody washes. In fact, bar soaps fell 6.5% to $949 million and liquid soaps shrankfrom $237 million to $233 million, but other categories rose, like the specialtysoaps, which rose 2.4% to $538 million (89).

An overall view of the U.S. and Western Europe (Big 5) market of solid barsand liquid soap alternatives (hand, shower, and bath) has been compiled for 2001from Euromonitor data and is shown in Table 5.13 (91,94). The European segmentof all the personal wash products market includes the body washes, mainly in thebath care segment; this probably also contains some more sophisticated cleansingitems. However the data shows that overall, the alternative cleansing sources, suchas liquid soaps, shower gels, and body washes, outpaced the bars significantly. Ascan be seen, the bar soap market share dropped to about 37% in the U.S., 25.6% inthe U.K., 22.4% in Italy, 19.5% in France, 12.2% in Germany, and 11.1% in Spain(Table 5.13) (91,94). For comparison, the Euromonitor statistics of the global soapmarket showed total sales of $8,975 million in 2001, of which Unilever, P&G, andColgate-Palmolive had a market share of 33, 11, and 10% respectively, while thekey leading global brands were Lux (10%), Dove (9%), and Palmolive (4%). Aslightly different estimate of the world toilet soap bar market values the globalretail value as US $9,650 million, and estimates that about $1,400 million isclaimed by syndet and combo bars (96).

The U.S. soap-bar market ranked by sales (million $) and market share in2001 and 2002, according to Euromonitor 2003, is represented in Table 5.14(9294). The data show a decrease of 3.8% in total bar sales in 2002 compared to2001. Dove bar sales and market share increased by 0.8 and 1.1%, respectively,while Dial bar sales fell 4.5% with a stagnant market share. In 2002 Olay bar salesdeclined seriously, dropping about 10% while losing 0.3% of the market.Unfortunately, except for Dove, all combo bar sales dropped significantly: 12.1%for Lever 2000, and 7.3% for Caress (Table 5.14). However the encouraging con-clusion, relevant for this topic, is that 5 of the 10 leading U.S. soap-bar vendors in2002 are combars with a total market share of 48.3%.

The European soap market in the five big countries also shows a significantincrease in the syndet/combo bar market share due to Doves impressive marketpenetration. According to Datamonitor data, during 20002001 Dove became theleader in France, Italy, and the U.K. with market shares of 16.7, 13.6, and 21.5%,respectively (Table 5.15) (95). However, except for Sebamed, with a market shareof 4.3% in Germany, no other syndet/combar is a leading vendor (Table 5.15) (95).


TABLE 5.13 Solid and Liquid Soap Markets 2001

Bar soaps Liquid soaps Shower gels Bath care Total

Sales ($a) % Sales ($a) % Sales ($a) % Sales ($a) % Sales ($a) %

U.S.A. 1538.4 36.8 502.2 12.0 1000.3 23.9 1141.8 27.3 4182.7 100.0France 118.8 19.5 59 9.7 347 57.1 83.3 13.7 608.1 100.0Germany 89.1 12.2 85.5 11.7 425.3 58.3 129.8 17.8 729.7 100.0Italy 151.9 22.4 115.4 17.0 149.6 22.0 261.8 38.6 678.7 100.0Spain 27.7 11.0 14.3 5.7 202.3 80.2 7.9 3.1 252.2 100.0U.K. 200.6 25.6 82.3 10.5 274.4 35.0 226.2 28.9 783.5 100.0Europe 588.1 19.3 356.5 11.7 1398.6 45.8 709 23.2 3052.2 100.0aSales revenue is in million USD.Source: Euromonitor 2001 (91,94).


TABLE 5.14 U.S.A. Bar Soap Market Share 20012002

2001 2002

Ranking Brand Sales ($a) % Market Sales ($a) % Market % Change (sales $)

1 Dove (Unilever) 336.6 22.6 339.4 23.7 0.82 Dial (Dial) 189.1 12.7 180.5 12.6 4.53 Irish Spring (Colgate) 147.4 9.9 144.7 10.1 1.84 Lever 2000 (Unilever) 138.5 9.3 121.7 8.5 12.15 Zest (P&G) 93.8 6.3 91.7 6.4 2.26 Ivory (P&G) 80.4 5.4 78.8 5.5 2.07 Caress (Unilever) 80.4 5.4 74.5 5.2 7.38 Olay (P&G) 71.5 4.8 64.4 4.5 9.99 Safeguard (P&G) 43.2 2.9 41.5 2.9 3.9

10 Coast (Dial) 35.7 2.4 31.5 2.2 11.811 Tone (Dial) 26.8 1.8 27.2 1.9 1.512 Jergens (Kao) 20.9 1.4 15.8 1.1 24.413 Pure & Natural (Dial) 4.5 0.3 4.3 0.3 4.414 Private Label 10.4 0.7 15.8 1.1 51.915 Others 210 14.1 200.5 14.0 4.5

Total Bar Soap 1489.3 100.0 1432.2 100.0 3.8aSales revenue is in million USD.Source: Euromonitor 2003 (9294).


In view of the above said the market share of the syndets in Israel goes on bybeing the highest in the world. According to Nielsen reports (97) in 2002 the mar-ket share (in bar units) was Neca 7 (30.0%), Hawaii (27.8%), Dove (13.8%),Palmolive (11.3%), Lux (9.2%), and Fa (3.2%), while the money spent for themarket share was Neca 7 (27.5%), Hawaii (25.5%), Dove (22%), Palmolive(9.6%), Lux (7.1%), and Fa (2.6%) (97). Obviously the differences in the units andretail value market share lies in the selling retail prices which are on average about$0.60 for the two leading syndets and $1.20 for Dove.

Future Trends

Milder formulations with enhanced skin care properties targeted to offer an aes-thetic, consumer-appealing appearance, seem to be a major trend in the future. Theemphasis on environmental care and the use of natural renewable raw materials,made exclusively from vegetable-based fatty materials, will continue to drivedevelopment.

A transparent neutral syndet, perceived by customers as a pure product, free ofany harmful ingredients will also be targeted as a specialty bar. A transparentextrudable neutral syndet, of reasonable costperformance, should be a supremechallenging target.

TABLE 5.15Market Shares of Leading European Bar Soaps (2000/2001)

France Germany Italy Spain U.K.(%) (%) (%) (%) (%)

Dove (Unilever) 16.7 10.3 13.6 11.5 21.5Le Petit Marseillais (Lab Vendome) 12Mansavon (Sara Lee) 9.7Palmolive (Colgate) 8 10.3 5.3 4.5Nivea (Beiersdorf) 10.6CD (Unilever) 9.6LUX (Unilever) 8.1 6.3Sebamed (Sebapharma) 4.3FA (Henkel) 6.8Neutro Roberts (Manetti & Roberts) 8.4Fiori Roberts (Manetti & Roberts) 7.6Heno De Pravia (Perfumeria Gal) 26.8Magno (Henkel) 12.6Imperial Leather (Cussons) 18.5Simple (Smith & Nephew) 6Pearl (Cussons) 4.8

Syndet/Combars (Prices/Unit):France: Dove (0.91 Euro), Monsavon 2 in 1 (0.86 Euro).Germany: Dove (0.76 Euro), Sebamed (1.36 Euro), Nivea Milk Bar (0.77 Euro).Italy: Dove (1.10 Euro).Source: Symrise (95).


During the last few years, the soap bar evolved into a complex product thathas to satisfy multiple functional needs (hygiene, antibacterial protection, skincare, mildness, and crossover) and emotional pleasures (well being, soul care,attractive shape, decorative look and packaging) (99101). The realization of thesechallenging targets, creating new sensations in soap and wow products, willdrive new marketing strategies and continue innovation, which currently is moreimportant than ever for the future market of soap bars.

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