AU730992B2

AU730992B2 - Liquid compositions comprising stability enhancing surfactants and a method of enhancing low temperature stability thereof

Info

Publication number: AU730992B2
Application number: AU43839/97A
Authority: AU
Inventors: Richard Kolodziej; Sudhakar Puvvada; May Shana'a
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1996-09-24
Filing date: 1997-09-04
Publication date: 2001-03-22
Anticipated expiration: 2017-09-04
Also published as: AU4383997A; ID19362A; CN1275907A; MY131145A; CA2263981A1; JP2002500621A; PL332377A1; EP0928186A1; CO4920180A1; CZ104299A3; BR9711299A; WO1998013022A1

Description

r 6364 LIQUID COMPOSITIONS COMPRISING3 STABILITY EN34ANCING SURFACTANTS AND A METHOD OF ENHANCING LOW TEMPERTURE STABILITY THBREOF The present invention relates to lamellar structured liquid cleansing compositions such as those described, for example, in applicant's copending US Serial No 08/512,010 fled August 7, 1995. These compositions are generally used in skin cleansing Or shower gel compositions. In particular, the invention relates to such compositions in which the surfactatit system is carefully selected to ensure good stability aven at low temparatuc' 3torage -6.70C (2Qnl) and Wo1w down~ to 17.81C (0 0 F) and to a method of enhancing such low temperature stability by careful selection of the sarfactant system.

Typically, lamnellar structurd liquid cleansing comiposition (e.g.

shower, gel compositions) comprise a mixture of anionic surfactants (for cleansing and foaming attributes) and mild surfactant. In a typical shower formulation the mild surfactant may be an ampbotrric and/or zwitterionic surfactan such as those described in US Serial No 08.512,010 mentioned above, hereby incorporated by reference into the subject application.

In such lamnellar structured compositions, however it has been found that there is considerable thinning of product as the product is cooled down to temperatures of -6.7-17.8*C (200 to 0 0 F) This loss of viscosity is not a desirable property.

Unexpectedly, applicants have found that when allkalimetal alkyl amphoacetate is used as 25 to 90 prcerxably 30 to 90 and more preferably about 40)% to 90 of the amphoteric and/or zwitterionic AMENDED

SVAEEI

6 2 component, in the surfactant system in lamnellar structured compositions, there is a significant increase in product stability. The applicants have also found a method of enhancing low temperature stability of a lamellar structured liquid cleansing composition by selecting an alkali metal alJkylatnphoacetate as 25-90 of the amphoteric and/or zwitterionic surfactant in a composition further comprising anionic surfactant.

US Serial No 08/512,010 shows one example (Example IX at page Ico 23) where sodium cocoainphoacetate is used. However, in neither that example or in the other eight examples are there ever taught blends of other axnpboteric betaine) and amphoacetate. Nor is there any teaching or suggestion in that application that blends of aniphoteric wil ameliorate low temperature instability in such compositions. Indeed, until is the problem of low temperature instability was even appreciated, it could not have been known that the specifically selected surfactant system of the invention could ameliorate the problem.

W09612 14266 describes mild antibacterial cleansing compositions containing anionic surtactant, amphoteric surfactant, skin moisturizer ant.'bacteria] agent, and water, wherein the anionic and amphoteric surfactants are present at specified ratios and levels of the composition.

W094! 18292 describes personal cleansing compositions comprising 5-50% aniionic and/or amphoteric surfactants, 0.1-20% soluble or dispersible ethoxylated anionic surfactant, 1.5-10% water soluble citrate salt, up to 3% perfume or cosmetic oil and water.

The present invention relates to lamnellar structured liquid cleansing 3U compositions comprising 5 to 50 of a surfactant system wherein said 11

N

063 6L 2a surfactant system comprises a anionic or Mixture of anionics and Nb a blend of amphoteric and./or zwitterionic sur-factants wherein said blend comprises alk2limetal alkylamphoar-etate and said agkaixetal alkylamphoacetate comprises 25% to 90%, preferably 30% to 90% and inrr preferably 40% tn 90% 1f thi- hernr The present invention ftrther relates to a method of enhancing stability of low temperature compositions temperatures of from about io -6.7 to 17.8*C (20OF to about 0 0 OF) in lamellar structured liquid cleansing compositions comprising about .O,,Ewo

S"W

-C 6 3 6 4- 3 to about 50% of a surfactant system which surfactant SYSte in turn comprises: anionic or mixture of anionic surfactant; and an ariphoteric and/or zwitterionic surfactant or mixture thereof, wherein said method comprises selecting component such that the alkaLimetaW alkyl amphoacerate comprises greater thin 25 to 90 preferably about 30 to 90 more preferably about 40 to 90 of said compcnerit Unexpectedly, the applicants have found that when the alkalimetal flkylanphrmretpis mpt as it r i minimum amount of amphoteric/zwitterionic blend, the component significantly enhances cold temperature stability of the lamellar structured composition relative to compositions where the alkaimetal alicylamphoacetate does not comprise a portion or comprise less than" 25% of the amphoteric/zwitterionic blend.- The present invention is directed towards improving the low 2o temperature stability of lamnellar structured liquid compositions comprising an amphoteric and/or zwitreionic surfactant or mixture thereof.

According'to one aspect the present invention provides lamellar strctured liqaid cleansing compositions comprising about 5 to about 50% of a surfactant system which surfactant system in mmr comprises: anionic or mixture of anionic surfactant; and an amphoteric and/or zwitterionic suffactant or mixture thereof; 1 C6364 3a wherein alkalimetal alkyl amphoacetate comprises greater than to 90%, preferably about 30% to 90%. more preferably about 40% to of cotnponew1 and a siructurat selected from saturated or unsaturated, branched or unbrxched. Cs-Cz'i liquid fatty acids, or polyalkylene glycol fatty acid esters, capric or caprylic acid, or mixtures thereof.

W INDED S -AET 4 According to a further aspect the present invention provides a method of enhancing low temperature stability of a lamellar structured liquid cleansing compositions comprising 5% to 50% of a surfactant system which surfactant system comprises: anionic or mixture of anionic surfactant; and an amphoteric and/or zwitterionic surfactant or mixture thereof; wherein said method comprises selecting the amphoteric and/or zwitterionic surfactant component such that alkalimetal alkyl amphoacetate comprises greater than to 90% of said component According to a further aspect the present invention 15 provides a lamellar structured liquid cleansing composition comprising 5% to 50% of a surfactant system comprising: S:a) anionic or mixture of anionic surfactants; and o b) an amphoteric and/or zwitterionic surfactant or Smixture thereof; wherein alkalimetal alkylamphoacetate comprises 25% to 90% of component and a structurant selected from liquid fatty acids comprising oleic acid, isostearic acid, linoleic S..acid, ricinoleic acid, elaidic acid, arichodonic **acid, myristoleic acid, palmitoleic acid and 25 mixtures thereof, or prolyalkylene glycol fatty acid esters comprising S* propylene glycol isostearate, propylene glycol oleate, glyceryl isostearate, glyceryl oleate, polyglyceryl diisostearate, and mixtures thereof.

The anionic surfactant may be, for example, an aliphatic sulfonate, such as a primary alkane

C

8

-C

22 4a sulfonate, primary alkane C 8

-C

2 disulfonate, C 8

-C

22 alkene sulfonate, C 8

-C

2 hydroxyalkane sulfbnate or alkyl glyceryl ether sulfonate (AGS); or an aromatic sulfonate such as alkyl benzene sulfonate.

The anionic surfactant may also be an alkyl sulfate

C

12 alkyl sulfate) or alkyl ether sulfate (including alkyl glyceryl ether sulfates). Among the alkyl ether sulfates are those having the formula: RO (CH2CH20) nSO.M wherein R is an alkyl or alkenyl having 8 to 18 carbons, preferably 12 to 18 carbons, n has an average value of greater than 1.0, preferably between 2 and 3; and M is a solubilizing cation such as sodium, potassium, ammonium or substituted ammonium. Ammonium and sodium lauryl ether sulfates are preferred.

*o* *o WO 98/13022 WO 9813022PCTAEP97/04924 The anionic surfactant may also be alkyl sulfosuccinates (including mono- and dialkyl, CE-C 2 2 sulfosuccinates); alkyl and acyl taurates, alkyl and acyl sarcosinates, sulfoacetates, C.-C 2 2 alkyl phosphates and phosphates, alkyl phosphate esters and alkoxyl alkyl phosphate esters, acyl lactates, C 8

-C

2 2 monoalkyl succinates and maleates, suiphoacetates, and acyl isethionates.

Sulfosuccinates may be monoalkyl sulfosuaccinates havin g the formula: R Q.,CCWCH (SO,M) CO'M; amido-MEA sulfosuccinates of the formula R 4CONHCH.

2

CHOCCH

2 CH (SQIM) COM wherein R4 ranges tron CR-C,, alky.. and M is a solubilizing cation; amido-MIPA sulfosuccinates of formula RCONH CH(CH~ (SOM) Co M where M is as defined above.

Also included are the alkoxylated citrate sulfosuccinates; and alkoxylated sulfosuccinates such as the following: 0 11 R-0- (CH,CH,0) CCH.,CH (SO M) COM wherein n 1 to 20; and M is as defined above.

WO 98/13022 PCT/EP97/04924 6 Sarcosinates are generally indicated by the formula RCON(CH,)CHCOM, wherein R ranges from C, to alkyl and M is a solubilizing cation.

Taurates are generally identified by formula 2 3 R CONR CH 2

CH

2

SO

3

M

wherein R 2 ranges from C-C 2 0 alkyl, R ranges from C.-C alkyl and M is a solubilizing cation.

Another class of anionic surfactants are carboxylates such as follows:

R-(CH,CHO),CO,M

wherein R is C, to alkyl; n is 0 to 20; and M is as defined above.

Another carboxylate which can be used is amido alkyl polypeptide carboxylates such as, for example, Monteine LCQ by Seppic.

Another anionic surfactant which may be used are the C CI acyl isethionates. These esters are prepared by reaction between alkali metal isethionate with mixed aliphatic fatty acids having from 6 to 18 carbon atoms and an iodine value of less than 20. At least 75% of the mixed fatty acids have from 12 to 18 carbon atoms and up to 25% have from 6 to carbon atoms.

Acyl isethionates, when present, will generally range from about 0.5-15% by weight of the total composition.

Preferably, this component is present in an amount from 1 to 0* .fle~ LC a. WO 98113022 PCTIEP97104924 7 The acyl isethionate may be an alkoxylated isethionate such as is described in Ilardi et al., U.S. Patent No.

5,393,466, hereby incorporated by reference into the subject application. This compound has the general formula: O X Y II I I R C-O-CH-CH,-(OCH-CHJ)m-SO 3

M

wherein R is an alkyl group having 8 to 18 carbons, m is an integer from 1 to 4, X and Y are hydrogen or an alkyl group having 1 to 4 carbons and M is a monovalent cation such as, for example, sodium, potassium or ammonium.

In general the anionic surfactant component will comprise from 1 to 20% by weight of the composition, preferably 2 to 15%, most preferably 5 to 12% by weight of the composition.

The anionic surfactant mixture may comprise alkyl sulphates, acylisethionates and mixtures thereof.

The compositions of the present invention further comprise zwitterionic surfactants. Zwitterionic surfactants are exemplified by those which can be broadly described as derivatives of aliphatic quaternary ammonium, phosphonium, and sulfonium compounds, in which the aliphatic radicals can be straight or branched chain, and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. A general formula for these compounds is: 3 (R

)X

I

2 CH_ 4 R -Y -CH 2

-RZ

SUBSTITUTE SHFETUIRJI. 9f1 WO 98/13022 PCTIEP97/04924 wherein R 2*contains an alkyl, alkenyl, or hydroxy alkyl radical of from about 8 to about 18 carbon atoms, from 0 to about 10 ethylene oxide moieties and from 0 to about I glyceryl moiety; Y is selected from the group consisting of nitrogen, phosphorus, and sulfur atoms; R' is an alkyl or monohydroxyalkyl group containing about 1 to about 3 carbon atoms; X is 1 when Y is a sulfur atom, and 2 when Y is a nitrogen or phosphorus atom; R 4is an alkylene or hydroxyalkylene of from about 1 to about 4 carbon atoms and Z is a radical selected from the group consisting of carboxylate, sulfonate, sulfate, phosphonate, and phosphate groups.

Examples of such surfactants include: 4-fN,N-dj (2-hydroxyethyl) -N-octadecylamjnoniol-butane.lcarboxylate; 5-[S3hdoyrp Sheaeysloil3 hydroxypentane- 1-sulfate; 3- [PPdiethy-P369.trioxatetradexocylphooio1 2 hyrxpoaelpopae propane- 1-phosphonate; 3-(NNdmty -exdclmoi~roaelsloae 3- N-dimethyl-N-hexadecylammonio) 2 -hydroxypropane-lsulfonate; 4- [NN-di(2-hydroxyethyl)-N-(2 -hydroxydodecyl)ammonio 0

J

butane- l-carboxylate; 3- [S-ethyl-S- 3 -dodecoxy-2-hydroxypropyl) sulfoniol propane- 1-phosphate; 3- P-dimethyl-P-dodecylphosphoniol -propane-lphosphonate; and (N,N-di (3-hydroxypropyl) -N-hexadecylamionioj -2hydroxy-pentane. -sulfate.

CI WO 98/13022 PCT/EP97/04924 9 Amphoteric detergents which may be used in this invention include at least one acid group. This may be a carboxylic or a sulphonic acid group. They include quaternary nitrogen and therefore are quaternary amido acids. They should generally include an alkyl or alkenyl group of 7 to 18 carbon atoms. They will usually comply with an overall structural formula: R -N -X-Y

I

where R is alkyl or alkenyl of 7 to 18 carbon atoms; R and R are each independently alkyl, hydroxyalkyl or carboxyalkyl of 1 to 3 carbon atoms; n is 2 to 4; m is 0 to 1; X is alkylene of 1 to 3 carbon atoms optionally substituted with hydroxyl, and Y is -CO 2 or -SO 2 3 Suitable amphoteric detergents within the above general formula include simple betaines of formula:

R

I

R -N

CHCO

2 3

R

and amido betaines of formula: arP**I a- WO 98/13022 WO9813022 PCTIEP97/04924 10

R

II

R CONH(CH.,)-N*--CH2CO.,

R

1 where m is 2 or 3.

Betaines are typically present in the compositions of the present inventions in amounts of 0 to 25% by weight, for example, 0.1 to 25% by weight.

In both formulae R R and R are as defined previously. R may in particular be a mixture of and C,.

alky] groups derived from coconut so that at least half, preferably at least three quarters of the groups R I have to 14 carbon atoms. R and R are preferably methyl.

A further possibility is that the amphoteric detergent is a sulphobetaine of formula

R

R N (CHj),SO,

R

or

R

I

1 R CONH

(CH

2

-N-(CH

2 3

SO

3

R

where m is 2 or 3, or variants of these in which

(CH

2 ),SO is replaced by

OH

-CH,CHCH,

SO,

WO 98/13022 PCT/EP97/04924 11 In these formulae R R and R are as discussed previously.

The amphoteric/zwitterionic surfactant generally comprises 0.1 to 20% by weight, preferably 5% to 15% of the composition.

A critical aspect of this invention is that the zwitterionic/amphoteric compounds must be used in blends of zwitterionic/amphoteric wherein one component of the blend is an alkalimetal alkylamphoacetate. Further, the alkali metal alkylamphoacetate must comprise 25% to 90%, preferably to 90%, more preferably 40% to 90% of the blend.

Suitably the amount of alkalimetal alkylamphoacetate may be within the range 30 to 75%, for example 40 to 60%, of the blend.

Examples of alkalimetal alkyl amphoacetate compounds include, but are not limited to, sodium or potassium lauro or cocoamphoacetate The total amount of amphoteric/zwitterionic including the amphoacetate, preferably should be no greater than more preferably no greater than 15%. The total amphoteric/zwitterionic should comprise at least 5% of the composition.

In addition to one or more anionic and amphoteric and/or zwitterionic, the surfactant system may optionally comprise a nonionic surfactant.

The nonionic which may be used includes in particular the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols, acids, amides or alkyl phenols with alkylene laBSTITUTE SHEET (RULE 26) WO 98/13022 PCT/EP97/04924 12 oxides, especially ethylene oxide either alone or with propylene oxide. Specific nonionic detergent compounds are alkyl 2 phenols-ethylene oxide condensates, the condensation products of aliphatic (C primary or secondary linear or branched alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine.

Other so-called nonionic detergent compounds include long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides.

The nonionic may also be a sugar amide, such as a polysaccharide amide. Specifically, the surfactant may be one of the lactobionamides described in U.S. Patent No.

5,389,279 to Au et al. which is hereby incorporated by reference or it may be one of the sugar amides described in Patent No. 5,009,814 to Kelkenberg, hereby incorporated into the subject application by reference.

Other surfactants which may be used are described in U.S. Patent No. 3,723,325 to Parran Jr. and alkyl polysaccharide nonionic surfactants as disclosed in U.S.

Patent No. 4,565,647 to Llenado, both of which are also incorporated into the subject application by reference.

Preferred alkyl polysaccharides are alkylpolyglycosides of the formula 2 R O(CAnH O)t(glycosyl) x wherein

R

2 is selected from the group consisting of alkyl, alkylphenyl, hydroxyalkyl, hydroxyalkylphenyl, and mixtures thereof in which alkyl groups contain from about to about 18, preferably from about 12 to about 14, carbon atoms; n is 0 to 3, preferably 2; t is from 0 to about C%2 I~e-WN I rv_ 11 41 G a- WO 98/13022 PCTEP97/04924 13 preferably 0; and x is from 1.3 to about 10, preferably from 1.3 to about 2.7. The glycosyl is preferably derived from glucose. To prepare these compounds, the alcohol or alkylpolyethoxy alcohol is formed first and then reacted with glucose, or a source of glucose, to form the glucoside (attachment at the 1-position). The additional glycosyl units can then be attached between their 1-position and the preceding glycosyl units 4- and/or 6-position, preferably predominantly the 2-position.

Nonionic comprises 0 to 10% by wt. of the composition.

In general, the compositions of the invention are soapfree compositions.

The present invention provides compositions utilizing typically 0.1% to 15% by wt., preferably 1 to 10% by wt. of a structuring agent which works in the compositions to form a lamellar phase. Such lamellar phase is preferred because it enables the compositions to suspend particles more readily emollient particles) while still maintaining good shear thinning properties. The lamellar phase also provides consumers with desired rheology ("heaping").

More particularly, where the composition is not lamellar structured and enhanced particle suspension/enhancing is desired, it is usually necessary to add external structurants such as carbomers crosslinked polyacrylate such as Carbopol

R

and clays. However, these external structurants have poorer shear thinning properties that significantly reduce consumer acceptability.

The structurant is generally an unsaturated and/or branched long chain (C 8

-C,

4 liquid fatty acid or ester derivative thereof; and/or unsaturated and/or branched long 0- rue (E0111 F 9 WO 98/13022 PCT/EP97/04924 14 chain liquid alcohol or ether derivatives thereof. It may also be a short chain saturated fatty acid such as capric acid or caprylic acid. While not wishing to be bound by theory, it is believed that the unsaturated part of the fatty acid of alcohol or the branched part of the fatty acid or alcohol acts to "disorder" the surfactant hydrophobic chains and induce formation of lamellar phase.

Examples of liquid fatty acids which may be used are oleic acid, isostearic acid, linoleic acid, linolenic acid, ricinoleic acid, elaidic acid, arichidonic acid, myristoleic acid and palmitoleic acid. l::tor derivatives include; propylene glycol Isostearatu, propylene (lycol oleate, glyceryl isostearate, glycery oleate and polyglyceryl diisostearate.

Examples of alcohols include oleyl alcohol and isostearyl alcohol. Examples of ether derivatives include isosteareth or oleth carboxylic acid; or isosteareth or oleth alcohol.

The structuring agent may be defined as having melting point below about 25C centigrade.

One of the principle benefits of the invention is the ability to suspend oil/emollient particles in a lanellar phase composition.

Various classes of oils are set torth below.

Vegetable oils: Arachis oil, castor oil, cocoa butter, coconut oil, corn oil, cotton seed oil, olive oil, palm kernel oil, rapeseed oil, safflower seed oil, sesame seed oil and soybean oil.

WO 98/13022 WO 9813022PC-T(EP97104924 15 Esters: Butyl ryristate, cetyl palmitate, decyloleate, glyceryl laurate, glyceryl ricinoleate, clcer-yl stearate., glyceryl isostearate, hexyl laurate, isobutyl palmitate, isocetyl stearaLe, isopropyl isosterArate, isopropyl laurate.

isopropyl linoleate, isopropyl myristate, isopropyl palmitate, isopropyl stearate, propylene glycol monolaurate, propylene glycol ricinoleate, propylene glycol stearate, and propylene glycol isostearate.

Animal Fats: Acetylated la~nol.in aiconcls, lanolin, lard, mink oil and tallow.

Fatty acids and alcohols: Ibehenic acid, palmitic acid, stearic acid, behenyl alcohol, cetyl alcohol, elcosany.

alcohol and isocetyl alcohol.

Other examples of oil/emoljnts include mirnerai oil, petrolatumn, silicone oil such as~ dirnothyl polysiloxane, lauryl arid myristyl lactate.

It should be understood that where the emollient may also function as a structurant, it should not be doubly included such that, for example, if the otructurant is oleyl alcohol, no more than 5% oleyl alcohol as "emollient" would be added since the emollient (whether functioning as emollient or structurant) never comprises more than preferably no more than 15% of the composition.

The emollient/oil is generally used in an amount of I to 20%, preferably 1 to 15% by wt. of the composition.

Generally, it should comprise no more than 20% of the composition.

in addition, the compositions of the invention may include optional ingredients as follows: WO 98/13022 PCT/EP97/04924 16 Organic solvents, such as ethanol; auxiliary thickeners, such as carboxymethylcellulose, magnesium aluminum silicate, hydroxyethylcellulose, methylcellulose, carbopols, glucamides, or Antil from Rhone Poulenc; perfumes; sequestering agents, such as tetrasodium ethylenediaminetetraacetate (EDTA), EHDP or mixtures in an amount of 0.01 to preferably 0.01 to 0.05%; and coloring agents, opacifiers and pearlizers such as zinc stearate, magnesium stearate, TiO, EGMS (ethylene glycol monostearate) or Lytron 621 (Styrene/Acrylate copolymer); all of which are useful in enhancing the appearance or cosmetic properties of the product.

The compositions may further comprise antimicrobials such as 2-hydroxy-4,2'4 trichlorodiphenylether (DP300); preservatives such as dimethyloldimethylhydantoin (Glydant XL1000), parabens, sorbic acid etc.

The compositions may also comprise coconut acyl monoor diethanol amides as suds boosters, and strongly ionizing salts such as sodium chloride and sodium sulfate may also be used to advantage.

Antioxidants such as, for example, butylated hydroxytoluene (BHT) may be used advantageously in amounts of 0.01% or higher if appropriate.

Cationic conditioners which may be used include Quatrisoft LM-200 Polyquaternium-24, Merquat Plus 3330 Polyquaternium 39; and Jaguar type conditioners.

Polyethylene glycols which may be used include: Polyox WSR-205 PEG 14M, Polyox WSR-N-60K PEG 45M, or WO 98/13022 PCT/EP97/04924 17 Polyox WSR-N-750 PEG 7M.

Thickeners which may be used include Amerchol Polymer HM 1500 (Nonoxynyl Hydroethyl Cellulose); Glucam DOE 120 (PEG 120 Methyl Glucose Dioleate); Rewoderm' (PEG modified glyceryl cocoate, palmate or tallowate) from Rewo Chemicals; Antil 141 (from Goldschmidt). A particularly preferred thickener is xanthan gum. Indeed, xanthan gum, particularly when used with the surfactant system of the invention, also helps ameliorate cold storage instability.

Another optional ingredient which mny be added are the defloculating polymers such as are taught in U.S. Patent No.

5,147,576 to Montague, hereby incorporated by reference.

Another ingredient which may be included are exfoliants such as polyoxyethylene beads, walnut sheets and apricot seeds.

The compositions of the present invention are typically personal products but are not to be construed as strictly limited thereto.

The invention will be described in greater detail by way of the following non-limiting examples. The examples are for illustrative purposes only and not intended to limit invention in any way. Further modifications within the scope of the present invention will be obvious to the skilled man.

Figure 1 shows cold temperature stability of various lamellar structured liquid cleansers at 15 and OF. As seen, when alkali metal amphoacetate comprises 25% of all amphoteric (for example, amphoacetate plus betaine), stability is dramatically increased.

18 All percentages in the specification and examples are by weight unless stated otherwise.

EXAMPLES

The following compositions are used in the examples: Ingredients I II I Cocoamido Propyl 12 9 6 Betaine Sodium 0 3 6 Lauroamphoacetate Sodium Cocoyl 6.5 6.5 Isethionate Sodium Laureth 6.5 6.5 Sulfate Thickener/Polymer 0.1 to 0.1 to 0.1 to Cationic, 1% 1% 1% Guar or Xanthan Gum) Emollient 1 to 7% 1 to 7% 1 to 7% Structurant 3 to 3 to 3 to 10% Titanium Dioxide 0.2 0.2 0.2 DMDM Hydantoin 0.2 0.2 0.2 Fragrance 1.0 1.0 BHT 0.0075 0.0075 0.0075 Water to to to 100.0 100.0 100.0 10 EXAMPLES 1-3 The compositions shown above in I-III were stored in plastic cups at 15'F and O'F for a period of 1 day and then equilibrated back to room temperature. Care was taken not to disturb the sample since viscosity increase when these a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a C6i364 19 products are shaken. The viscosity of the sample is then measured using a Brookfield RV Viscometer attached to a heliath accessory and using T- Bar Spindle A.

The results are set forth in Table 1 below: Example Amphoacetate T-Bar Viscosity in Betaine!' Amphoacetate Blend_____ Room ]After IDay FAfterlIDay Temperature at -9DC at -17.8 0

C

(15 0 F) (OOF) 88400 22800 22400 2 25 91200 26000 33200 350 87200 84000 83200 As seen fromi the Table and from Figure 1, (Examples 2 and 3), ID when amphoacetate comprises about 25% and greater, preferably about to 90 and most preferably about 40 to 90 of blend of amphoteric (betaine/amphoacetate blend), viscosity at low temperature 9 0 C (15 0 -17.8 0 C (OOF) remains much higher. Thus, clearly, low temperature viscosity/phase stability is much superior relative to compositions in which amphoacetate is not used or comprises less than of the blend Example 1).

AMLNOC-D' S4ET 19a Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

S.o *0 oo

Claims

1. A lamellar structured liquid cleansing composition comprising 5% to 50% of.a surfactant system comprising: a) anionic or mixture of anionic surfactants; and b) an amphoteric and/or zwitterionic surfactant or mixture thereof; wherein alkalimetal alkylamphoacetate comprises 25% to of component and c) a structurant selected from liquid fatty acids comprising oleic acid, isostearic acid, linoleic acid, ricinoleic acid, elaidic acid, arichodonic acid, myristoleic acid, palmitoleic acid and mixtures thereof, or polyalkylene glycol fatty acid esters comprising propylene glycol isostearate, propylene glycol oleate, glyceryl isostearate, glyceryl oleate, polyglyceryl diisostearate, and mixtures thereof.

2. A composition according to Claim 1 wherein alkalimetal alkylamphoacetate comprises 30 to 90% of component

3. A composition according to Claim 2, wherein alkalimetal alkylamphoacetate comprises 40% to 90% of components (b)

4. A composition according to Claim 1, wherein the anionic surfactant is selected from the group consisting of alkyl sulfates, acyl isethionates and mixtures thereof.

5. A composition according to Claim 1, wherein component comprises 0.1% to 25% betaine. 21

6. A composition according to Claim 1, wherein the composition additionally comprises 0% to 10% of nonionic surfactant.

7. A method of enhancing low temperature stability of a lamellar structured cleansing composition as claimed in Claim 1 wherein said method comprises selecting the amphoteric and/or zwitterionic surfactant component(b) such that alkalimetal alkyl amphoacetate comprises 25% to 90% of component

8. A method according to Claim 7, wherein alkalimetal alkylamphoacetate comprises 30% to 90% of component

9. A method according to Claim 8, wherein alkali metal alkylamphoacetate comprises 40% to 90% of component A method according to any one of Claims 7 to 9 wherein the lamellar structured liquid cleansing composition comprises one or more of the components of Claims 4 to 6.

11. A composition as hereinbefore described with reference to the examples. S* DATED THIS 22nd day of November, 2000. UNILEVER PLC By Its Patent Attorneys DAVIES COLLISON CAVE e C