CA2015868C

CA2015868C - Aqueous based personal washing cleanser

Info

Publication number: CA2015868C
Application number: CA002015868A
Authority: CA
Inventors: Alan Paul Green; Barbara Mcfarquhar; Rosa Paredes; Marianne Mellett; Frederick Silvio Osmer
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1989-05-05
Filing date: 1990-05-01
Publication date: 1995-07-18
Anticipated expiration: 2010-05-01
Also published as: CA2015868A1; BR9007347A; JP2514112B2; US5132037A; DE69010907T2; ES2057564T3; WO1990013283A1; EP0479795A1; EP0479795B1; AU634777B2; AU5561790A; JPH07501785A; DE69010907D1; ZA903408B

Abstract

An aqueous based personal washing product is disclosed which when used has good cleaning ability and is particularly mild to the skin. The free flowing liquid product is particularly adapted for facial washing and contains acyl ester of isethionic acid salt, long fatty acids and moisturizer component, and preferably a co-active surfactant.

Description

~ ~L
.

2015~6 AOUEOUS BASED PERSONAL WASHING CLEANSER

Technical Field lS
The present invention is in the field of aqueous based, surfactant containing, mild cleansers, providing good foaming, moisturizing and cleaning, without excessive harshness.
The use of moisturizers in traditional washing bars is severely limited by processing constraints. Usually bars with a high content of moisturizer are sticky and cannot be easily stamped. Some of the difficulties of 2s formulating a good personal washing product with high levels of moisturizers were eliminated by using liquid products to avoid the stamping problem.

Moisturizers have also been found to inhibit lathering. However, lathering is desirable for washing products. Further, a high concentration of moisturizers while being desirable for mildness and skin benefit has a tendency to de-stabilize liquid products.

It was thus desirable to formulate an aqueous based ~, -~ 2~

product containing high levels of moisturizers in combination with high levels of mild surfactants to result in a substantially stable personal washing product which is exceptionally mild to the skin; and having excellent lathering characteristics which also leaves the skin feeling smooth, silky, and moisturized.

Background Japanese Patent JP-A-63/243,200 discloses a detergent composition containing a combination of specified acyl isethionates, higher fatty acids and N-acylglutamic acid salts. US 4 556 510 and 4 617 148 both disclose liquid soaps containing polymeric thickeners along with several other surfactants including optionally sodium cocoyl isethionate. US 4 495 079 discloses a therapeutic facial skin cleanser composed of selected surfactant mixtures and active ingredients.

There have been many different approaches to the problem of producing an aqueous based mild cleanser containing high levels of emollients/moisturizers together with combinations of mild surfactants having good viscosity, good stability, and high lathering characteristics. None of these approaches has been completely satisfactory. In many cases, stability is sacrificed to improve viscosity, or mildness is de-emphasized to improve cleaning ability or moisturizing is minimized to improve lathering.

3~
Disclosure of the Invention - -According to the present invention there is provided a liquid aqueous based skin cleansing composition characterised in that it comprises (i) at least 3wt% acyl esters of isethionic acid salts, said esters being predominantly C8 to C22 acyl isethionates;

(ii) at least 2wt% of at least one long chain fatty acid having a major proportion of C16 or above; and (iii)at least 2wt% of a moisturizer component;

wherein the weight ratio of said acyl esters to said fatty acid ranges from about 1:0.1 to about 1:10, and soap is present in an amount from O to 5% by weight of the composition.

The presently defined aqueous based composition containing acylisethionates, fatty acid, and moisturizer component in specified amounts and ratios can provide a fluid aqueous based cleansing and moisturizing product characterized by its mildness, good lathering properties, acceptable viscosity and stability while subs~antially eliminating many of the problems of the art. Preferably a co-active surfactant is additionally present in an amount at least 2wt~ with respect to the total composition.

The inventive composition can have the advantages of mildness, good moisturizing, good lathering, and excellent long term stability. Other standard ingredients such as polymeric thickeners, preservatives, further co-surfactants, sequestrants, foam boosters, and the like may also be employed to advantage.

Preferably the composition comprises (i) 3 to 20wt% said acyl esters of isethionic acid;
3~

2~

(ii) 2 to 15 wt% said long chain fatty acid(s);

(iii)2 to 20wt% said co-active surfactant;

(iv) 2 to 15~ said moisturizer component.

Suitably the composition comprises at least 5wt% of said at least one long chain fatty acid, at least 5wt% of said co-active surfactant and at least 5wt% of said moisturizer component.

The formulation may suitably contain the following general ingredients provided an appropriate viscosity is achieved:

Ingredients wt~

acylisethionate 3-20%
fatty acids 2-15%
20 moisturizer 2-15%
co-surfactant 2-20%
preservative 0.1-1%
sequestrant 0.01-0.1%
standard additives 3-15%
25 water balance AcYlisethionate A critical component of the formulations of the present invention is a non-soap anionic surface active -agent. Particularly suitable agents for the present invention are the C8-C22 acyl isethionates. These esters may be prepared by the reaction between alkali metal isethionate and mixed aliphatic fatty acids having from 8 to 22 carbon atoms and an Iodine Value of less than 20.
In one embodiment of the invention at least 75% of these mixed fatty acids should preferably have from 12 to 18 carbon atoms and up to 25~ should have from 8 to 10 carbon atoms.
S

Another suitable syndet is that of alkyl glycerol ether sulfonate. Alkyl chains for this surfactant are from C8 to C22~ preferably C10 to C18. It is envisaged that the present compositions could be prepared containing alkyl glycerol ether sulfonate in place of or as well as the acyl isethionate.

Co-active surfactant A number of anionic, nonionic, cationic and amphoteric surfactants may be employed as the co-active.
In copending case US Serial Number 340,185 filed on April 19, 1989, co-active combinations in bars with acyl isethionates are disclosed. Among suitable anionic co-actives are the alkyl sulfates, alkyl ether sulfates, alkyl ether sulfonates, sarcosincates, sulfosuccinates, taurates and combinations thereof. Among suitable amphoteric co-actives may be included alkylbetaines, amidopropyl betaines, amidopropyl sultaines and combinations thereof.

The relative amounts of isethionate esters to co-actives will preferably range in the weight ratio of about 20:1 to about 1:1, preferably from about 5:1 to about 2:1, optimally about 3:1. -Alkyl ether sulfates will be of the general formula R-O(CH2CH2)nOS03-M wherein R ranges from C8-C20 alkyl, preferably C12-C15 alkyl, n is an integer from 9 to 40, 201~868 preferably from 10 to 20, optimally about 12, and M is a sodium, potassium, ammonium or triethanolammonium cation.
Typical commercial co-actives of this variety are listed in the Table below:

Trademark Chemical Name Physical Manu-Form facturer Alkasurf ES-60 Sodium Laureth Paste Alkaril Sulfate Cycloryl TD TEA Laureth Paste Cyclo Sulfate Standapol Sodium Laureth-12 Liquid Henkel 125-E Sulfate Cedepal Sodium Trideceth Paste Miranol TD407MF Sulfate Standapol T TEA Lauryl Sulfate Liquid Henkel Alkyl ether sulfonates may also be employed in the present composition. Illustrative of this category is a commercial product known as Avenel S-150 commonly known as a sodium C12-C15 Pareth-15 sulfonate.

Another co-active type suitable for use in the present composition is that of the sulfosuccinates. This category is best represented by the monoalkyl -sulfosuccinates having the formula:
RO2CCH2CH(SO3-Na )COO-M ; and amido-MEA sulfosuccinates of the formula: RCONHCH2CH2O2CCH2CH(SO3-M ~CCO-M ; wherein R
3s ranges from C8-C20 alkyl, preferably C12-C15 alkyl and M

2t~S868 is a sodium, potassium, ammonium or triethanolammonium cation. Typical commercial products representative of these co-actives are those listed in the Table below:

Trademark Chemical Name PhYsical Manu-Form facturer Emcol 4400-1 Disodium Lauryl Solid Witco Sulfosuccinate Schercopol Disodium Cocoamido Liquid Scher CMSNa MEA Sulfosuccinate Emcol 4100M Disodium Paste Witco Myristamido MEA
Sulfosuccinate Schercopol Disodium Oleamido Liquid Scher MEA

Varsulf S13333 Disodium Solid Scherex Ricinoleamido MEA
Sulfosuccinate Sarcosinates may also be useful in the present composition as a co-active. This category is indicated by the general formula RCON(CH3)CH2CO2-M , wherein R ranges from C8-C20 alkyl, preferably C12-C15 alkyl and M is a sodium, potassium, ammonium or triethanolammonium cation.
Typical commercial products representative of these co-actives are those listed in the Table below: -2~8~8 Trademark Chemical Name Physical Manu-Form façturer Hamposyl L-95 Sodium Lauroyl Solid W.R.
Sarcosinate Grace Hamposyl TEA Cocoyl Liquid W.R.
TOC-30 Sarcosinate Grace Taurates may also be employed in the present composition as co-actives. These materials are generally identified by the formula RCONR CH2CH2S03-M , wherein R
ranges from C8-C20 alkyl, preferably C12-C15 alkyl, R1 ranges from C1-C4 alkyl, and M is a sodium, potassium, lS ammonium or triethanolammonium cation. Typical commercial products representative of these co-actives are those listed in the Table below:

Trademark Chemical Name Physical Manu-Form facturer Igepon TC 42 Sodium Methyl Paste GAF
Cocoyl Taurate 25 Igepon T-77 Sodium Methyl Paste GAF
Oleoyl Taurate Within the category of amphoterics there are three general categories suitable for use in the present compositions. These include alkylbetaines of the formula RN (CH3)2CH2C02-M , amidopropylbetaines of the formula -RCNHCH2CH2CH2N (CH3)2CH2CO~-M , and amidopropyl sultaines of the formula RCONHCH2CH2N (CH3)2CH2S03-M , wherein R
ranges from C8-C20 alkyl, preferably C12-C15 alkyl, and M
is a sodium, potassium, ammonium or triethanolammonium ~ 2~5868 cation. Typical commercial products representative of these co-actives are found in the Table below:

Trademark Chemical Name PhYsical Manu-S Form facturer Lonzaine C Cocamidopropyl Liquid Lonza Betaine Lonzaine CS Cocamidopropyl Liquid Lonza Hydroxysultaine Lonzaine 12C Coco-Betaine Liquid Lonza lS Schercotaine Myristamidopropyl Liquid Lonza MAB Betaine Velvetex Oleyl Betaine Paste Henkel Within the broad category of liquid co-actives, the most effective are the alkyl sulfates, alkyl ether sulfates, alkyl ether sulfonates and sulfosuccinates.

Lonq chain fattY acids Free fatty acids of 8-22 carbons are desirably incorporated within the compositions of the present invention. These fatty acids are present to operate as lather enhancing agents and as skin feel, lubricity, and --creaminess enhancers. The agents may be selected from fatty acids of carbon atoms numbering 8-18 in an amount up to about 15~ by weight of the composition. The most 3s important agent is a stearic acid/palmitic acid mixture.

2~3~s868 Levels of these acids can range from 1% up to 15% by weight so as to provide a major proportion of C16 and above. A combination of principally palmitic and stearic acids of about 45wt% stearic and 55wt% palmitic is preferred.

Moisturizer component Moisturizers are included to provide skin conditioning benefits and to improve the mildness of the product. The selection of the levels and types of moisturizers to be incorporated into the product is done in such a manner as not to affect adversely the stability of the product or its in-use characteristics, and still deliver good moisturization and lather.
The term "moisturizer" is often use synonymously with the term emollient, and is then meant to describe a material which imparts a smooth and soft feeling to the skin surface.
One way of reducing water loss from the stratum corneum is to deposit on the surface of the skin a layer which reduces the rate of evaporation. Another method is 2s to add hygroscopic substances, which will retain water, to the stratum corneum, to make this water available to the stratum corneum.

Both types of moisturizers as well as mixtures of these are operative in the present invention. Some examples of moisturizers are long chain fatty acids, -liquid water-soluble polyols, glycerin, propylene glycol, sorbitol, polyethylene glycol, ethoxylated/propoxylated ethers of methyl glucose and ethoxylated/propoxylated ethers of lanolin alcohol. Thus the present composition z~s~

requires the presence of long chain fatty acids and in addition another moisturizer.

The moisturizers useful in the present invention, including the long chain free fatty acids, are preferably used at a level of in total about 5% to 35% by weight of the composition. The preferred and more preferred levels of total moisturizers are, respectively, 5wt% to 30wt% and 8wt% to 20wt%. The most preferred moisturizer combination is a mixture of propylene glycol and a combination of stearic and palmitic acids having a weight ratio of glycol to acid of 1:3 to 5:1. The moisturizer combination, at the above levels, provides superior moisturization. The high level of moisturizer can provide enhanced mildness.

The moisturizer to soap weight ratios when soap is used are preferably 7 to 1 and, more preferably, 4 to 1.

Other moisturizers are compounds found naturally in the stratum corneum o~ the skin.

Moisturizers also include petrolatum, mineral oil, beeswax, silicones, lanolin and oil-soluble lanolin derivatives, saturated and unsaturated fatty alcohols and 2s various animal and vegetable oils.

Soaps Soaps may optionally be included in the compositions of the present invention as a structurant.

Soaps can be used at levels of preferably about 5%
and most preferably at a level of about 2% by weight. The soaps may be added neat or made in situ via adding a base, e.g., NaOH to convert free fatty acids.

~ 2~

Other ingredients Free sodium isethionate in an amount of about 1% to about 7% by weight affects stability and viscosity and may also affect mildness and can suitably be included in the present composition. It can either be added as a separate ingredient or may be present in commercially available acyl isethionate.

Standard additives such as colouring agents, opacifying agents e.g. Tio2l thickenrs e.g. carbopols may be used with the present compositions in varying amounts to insure appropriate benefits.

lS Sequestering agents such as EDTA, ethylene diamine tetraacetic acid trisodium salt of EHDP [disodium (l-Hydroxyethylidene) biphosphate] or mixtures of these in amounts ranging from 0.01 to as high as l.Owt~ preferably about 0.01 to 0.05wt~ may be used.

Preservatives such as antimicrobials or antimould/fungus agents may be used. Examples of these are methyl paraben (p hydroxymethylbenzoate); propyl paraben (p hydroxypropylbenzoate); and Dowicil 200 [N-(3-chlorallyl) Hexaminium chloride]. These and other similar materials may be used in amounts of about O.lwt%
to about 0.5wt% and may be used separately or in combination.

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

Viscosity 2~8~i8 Viscosity of the formulation is measured with a Brookfield cone and plate H.B.D.V. II viscometer at 2 min., 25C and a shear rate of ls 1. The viscosity of the present compositions can vary from about 100 cps to about 30,000 cps or higher if desirable, and will preferably be from about 10,000 cps to 15,000 cps.

Lather Lather evaluations are done by applying a two gram sample to the hands, followed by applying six millilitres of water. The hands are then placed palm to palm and rotated five times in a circular motion in order to dissolve the product. The product is then "worked up" by rotating the hands ten times. The resulting lather is measured by immersing the hands in a distilled water bath and lowering a funnel, whose neck has been fitted with a graduated cylinder, over the hands, so that the volume of lather can be measured.

Selected combinations of acyl isethionate and stearic/palmitic acid can show improved lathering.

Embodiments of the Invention The invention will now be illustrated with reference to the following Examples, which are by way of example only. Unless otherwise indicated all percentages are by weight.

Example I -An aqueous based formulation embodying the present invention contains the following ingredients in the 3s indicated amounts:

Inqredients wt%

Sodium cocoyl isethionate 11%
Stearic acid 8%
Propylene glycol 10%
Sodium isethionate 5%
TEA lauryl sulfate 5%
Sodium soap * (82/18) 2.5%
Sodium alkylbenzene sulfonate 2%
Fragrance 0.4%
Methylparaben 0.20%
Propylparaben 0.10%
Dowicil 200 0.10%
EDTA 0.02%
EHDP 0.02%
BHT 0.008%
Water to 100.00%

* A mixture of 82wt% tallow soap and 18wt% coconut 20 soap.

Process A batch of the present formulation is prepared as 25 follows. Some of the numbers are approximate since commercial solutions vary in content.

A submix is first prepared by charging 1451.lkg (3,200 lbs.) of propylene glycol to a tank with agitation.
916 kg (2,019.20 lbs.) of sodium isethionate is added with slow speed agitation. 532.5kg (1,174.40 lbs.) of a slurry ~
containing 293kg (645.9 lbs.) of sodium alkyl benzene sulfonate is then added and mixing is continued to ensure uniformity. 1814.5kg (4,000 lbs.) of a 40% solution of 3s triethanolamine lauryl sulfate is then added and mixed until uniform at a temperature of about 26.6C to 32.2C
~80 to 90F). This submix is then set aside for future use.

6159 kg (13,577.76 lbs.) of deionized water is heated and charged to the main mixing tank and is maintained at about 82.2C (180 degrees F). The previously prepared submix is then slowly added with slow speed agitation.
2871 kg (6,329.6 lbs.) of a commercial preparation of sodium cocoyl isethionate is then added. This material contains 55wt% sodium cocoyl isethionate; 30wt% long chain fatty acids; 8wt% sodium isethionate and 7wt%
miscellaneous; 348.5kg (768 lbs.) of soap; 29kg (64 lbs.) of methyl paraben, 14.5 kg (32 lbs.) of propyl paraben, 7.5 kg (16.32 lbs.) of EDTA and 5 kg (10.56 lbs.) of EHDP
are added with mixing at about 5 minute intervals. 273 kg (601.60 lbs.) of stearic acid is then added and agitation is increased as necessary to achieve uniformity. The entire batch is then mixed at 79.4C to 82.2C (175 to 180 F) to ensure uniformity. The batch is then slowly cooled to about 46.1C (115F). 14.5 kg (32 pounds) of Dowicil is mixed into 18 kg (65 lbs.) of cold deionized water and this mixture is added to the batch. A
previously prepared homogeneous fragrance mix composed of 2s 58 kg (128 lbs.) of perfume and 1 kg (2.56 lbs) of BHT are added and mixed into the batch. The entire batch is then mixed and cooled to reach a suitable viscosity.

Thickener slurries may, of course, optionally be used at appropriate points. These slurries may contain suitable materials such as polymers, e.g. carbopol, gums -and the like.

3s 72 ~

This Example illustrates the equivalency in mildness between a composition A embodying the present invention and a 50% aqueous slurry of a commercial non soap detergent bar B. The percentages of B are approximate.
Table I lists the two compositions.

TABLE I

Formulations A %wt/wt. B %wt./wt.

Sodium Cocoyl Isethionate 10.95 25.0 Stearic Acid * 8.01 10.0 Na Soap (82/18 tallow/ 2.40 5.5 coconut) Sodium Alkylbenzenesulfonate 2.02 1.0 Sodium Isethionate5.09 2.4 TEA Lauryl Sulfate5.00 --20 Propylene Glycol 10.00 --Cosmedia Guar C-2610.50 --(guar gum/thickener) 2s Methylparaben 0.20 --Propylparaben 0.10 --Dowicil 200 0.10 --Viscasil 60M (silicone) 1.00 --Perfume 0.10 0.5 35 Lower Fatty acid -- 1.5 Miscellaneous solids -- 1.7 & electrolytes Water to 100.00 to 100.00 C14 3%; C16 = 50%; C18 = 47%

Both formulations were tested by Flex Wash. Table II
lists the Flex Wash outcome which confirms the equivalent mild behaviour of Formulation A to a 50% slurry of a commercial bar whose major ingredient is sodium cocoyl isethionate.

TABLE II

Flex Wash Test Sample Mean Scores * Mean Rank 20 Erythema Endpoint Erythema A 1.385 13.62 B 1.385 13.38 Statistical Analysis Rank Score: P = 0.9580 (Wilcoxon 2 sample) * Mean end point scores are the mean of the evaluation 3~ scores at which the first arm received a grade "2" or greater erythema score or at the completion of nineteen -washes.

The Flex Wash Test 3s 2~

The Flex Wash procedure consists of four daily 60 second washes of the antecubital fossa (flex area of elbow). This method was designed to produce erythema quickly. Erythemal response varies only slightly with temperature and humidity fluctuations making the protocol suitable for year round testing.

Approximately 15 panelists were used as the test population. Panelist flex areas must be free of any skin condition (eczema, dryness, irritation, cuts or abrasions). Anyone taking antihistamines, anti-inflammatory drugs or topical, oral or injectable cortisone on a regular basis was excluded from the study.
The panel was divided into two subgroups which were balanced for left handedness. Group I was assigned composition "A" for the left flex and "B" for the right flex. Group II reversed the order.

Following an evaluation, the panelist was instructed 20 to moisten the left flex area. A sponge was dampened with tap water (100 ppm calcium/magnesium ions). A fixed amount of test product was applied to the sponge. The "dosed" sponge was placed in the panelist's right hand.
The panelist then washed the left flex area for exactly 60 2s seconds (approximately 120 strokes). Thereupon, the flex was rinsed and patted dry. This washing procedure was repeated on the right arm with the appropriate composition. Washing by this procedure was repeated 4 times daily for four days and 3 times on the fifth day for a total of 19 washes. Treatment times were scheduled 1.5 hours apart. Each test site was evaluated immediately -prior to washing and 4 hours after the third daily wash.

One trained assessor evaluated test sites prior to each wash and 4 hours after the third wash of the fifth ~ S~8 day for a total of 20 evaluations. The grading scale was as follows:

0 - no erythema 0.5 - barely perceptible erythema 1 - mild spotty erythema/no oedema 1.5 - mild/moderate erythema/with or without oedema 2 - moderate confluent erythema/with or without oedema or vesiculation Each site was treated in the prescribed method until a grading of "2" or greater was attained or 19 washings had been completed. When a score of "2" or greater was attained the treatment was discontinued on that flex. The final score was then carried through for all remaining evaluations. The remaining flex was washed until either a grading of at least "2" or 19 treatments were attained, whichever was first. In this Example, the final grading is the sum total of grade scores for 20 assessments per panelist averages over the scores from ail panelists.
Thus, theoretically the average score could range from 0 to 38; the lower value indicating absolutely no skin irritation with the latter being severe. In practice, scores generally range from 15 to 30.
2s Arm Wash The objective is to compare the levels of irritation and/or dryness of two products on skin by assessing the 3~ changes in skin condition during exaggerated use conditions. Changes are assessed both visually and -instrumentally.

The subject/panelist is in the age group of 18-55 years. The subject must have been screened for soap sensitivity and found to be sensitive to the screening solution. The target site must be free of cuts and abrasions and have a grade "0" for both erythema and dryness following a two week preconditioning period.

The subject must refrain from using creams, lotions or other types of moisturizing products over the target body area (the forearms) throughout the duration of the test.

Subjects with allergies to soap and fragrances, a history of skin disease or currently undergoing treatment for a dermatologic condition or who did not respond positively to the soap sensitivity screening test as well as subjects currently within the 2 weeks prior to the start date, taking antiinflammatory agents are excluded.

Experimental Desiqn Subjects are re~uired to precondition their skin using the conditioning product supplied under normal use conditions. This preconditioning period is two weeks in length immediately prior to the onset of the study. Use of the preconditioning product will continue throughout the study for all bathing and showering.

A group panel of 30 subjects is randomly selected based on an acceptable skin condition score for dryness and erythema established at baseline. The panel is randomly balanced for age and sex and each panelist is assigned a subject number. Laboratory wash treatments are -for two morning sessions and two afternoon sessions over a four day test period. The fifth day includes two morning washes. The time interval between treatment and final 3 5 assessment are standard within the panel.

Visual and tactile assessments are conducted immediately before each wash treatment to evaluate and compare changes in skin condition. A final visual assessment is conducted.

The target site is the volar surface of the forearm from the antecubital fossa (flex area) to the wrist.

Subjects are supplied with blinded product for all home bathing and are instructed to avoid washing the test site during the test week.

Wash Procedure All wash treatments are conducted by a technician.
Both forearms are washed simultaneously taking care to exert equal pressure/force to each arm. Technicians alternate their treatment groups at each wash interval.

1. Using water maintained at 32C (90F) each ~orearm is wet thoroughly from the flex area to the wrist.

2. The product is placed on a wet pad and spread over the pad. The treated pad is then placed on the designated arm and is then gently glided up and down the volar surface of the forearm for two minutes.

3. The arm is rinsed under running water for 30 seconds and patted dry gently with a soft disposable towel.

Visual Assessment ~

A trained skin evaluator conducts all visual assessments. The forearms are assessed for erythema and dryness immediately prior to each wash treatment. A five point scoring scale (0-4) is used to assess skin condition for both dryness and erythema. Half point increments are used to denote slight differences between arms or for responses not warranting a full point increase.

Dryness Erythema O - None O - None 1 - Slight flaking 1 - Mild erythema 2 - Moderate flaking/scaling 2 - Moderate confluent erythema 3 - Marked scaling, slight 3 - Marked erythema fissuring 4 - Severe scaling, fissuring 4 - Deep erythema Forearms are treated until a grade "3" or greater erythema or dryness develops (end point score). Once an end point score is attained treatment of both sites is discontinued. The final visual assessment is conducted approximately three hours after the last wash.

The arm wash test described above was run comparing the following two products. Formulation C embodies the present invention, whilst Formulation B is a comparative product.

3~

2~

Table III

Ingredients Form. C Comparative Form. B
% wt/wt S
Sodium Cocoyl Isethionate 10.95 25 Stearic Acid 8.01 10 Sodium Soap 2.40 5.5 Sodium Alkylbenzenesulfonate 2.02 1.0 Sodium Isethionate 5.09 2.4 TEA Lauryl Sulfate 5.00 --Propylene Glycol 10.00 --Methylparaben 0.20 --15 Propylparaben 0.10 --Dowicil 200 0.10 --Fragrance 0.10 0.5 Lower Fatty acid 1.5 Miscellaneous solids -- 1.5 & electrolytes Water to 100.00 to 100.00 As in Table I, Formulation B represents a 50% slurry of a commercial bar. The percentages are thus approximate. Formulation C has no guar gum or viscasil.
The test was run to compare the mildness/irritation potential of cleanser C with a 50% slurry of a commercial bar B. The test site was treated with one gram of slurry B or 0.5 gram of the facial cleanser C.
3~

Table IV

RESUhTS OF ARM WASH TEST:

MEAN SCORES * END POINT END PQINT
ERYTHEMA DRYNESS

Slurry B 1.000 1.531 Product C 1.250 1.563 MEAN RANK: ERYTHEMA DRYNESS

Slurry B 13.88 15.81 Product C 19.13 17.19 STATISTICAL ANALYSIS OF
RANK SCORES: p=0.0981 p=0.6844 (Wilcoxon 2 sample) * Mean end point scores are the mean of the evaluation scores at which the first arm receives a grade "2" or greater erythema score or grade "3" dryness score or at the completion of nineteen washes.

The results indicated no significant difference (P<0.05) between Product B slurry and Product C based on the mean rank erythema and dryness scores at end point.
Product C was somewhat more irritating than the slurry.

SUMMARY -The inventive composition has been evaluated in clinical studies against a slurry of a commercial bar.
3s 2~S~

In the Flex Wash against the slurry, the scores for the present composition were identical to the slurry scores for erythema. In the Arm Wash test, the present composition scores for dryness were very close to those of the slurry. There were some negative differences between the present composition score and the slurry for erythema in the Arm Wash.

Table V

Slurry Present Composition Flex Wash Erythema 1.385 1.385 Arm Wash Dryness 1.531 1.563 Arm Wash Erythema 1.000 1.250 Facial Wash Study The test group includes 35 subjects/panelists in the age group of 18 to 55 years. The subject must have no history of allergies or skin diseases. Panelists must refrain from using facial creams, lotions or other type of moisturizing products on their faces throughout the duration of the test period. Upon admittance to the 2s study, each subject is provided with (2) bars of commercial soap to be used at home for a two week period prior to the start of testing.

Eligible panelists are assigned test products selected at random to equal a Right/Left or Left/Right balance in product assignment to each half-face side. ~

Assigned Groups Include:

3 5 Group I Right half, Code B Group II Right half, Code A

~ 21~S~6~

Left half, Code A Left half, Code B

Procedure The schedule of wash treatments includes a single facial wash conducted both in the morning and afternoon and for four consecutive test days or a total of 7 wash treatments. Panelists are instructed not to use anything on their faces except to wash with warm water and face cloth.

Each subject has their face washed in the following manner by a technician:

a) Wet both sides of the face 10 seconds b) An abundant lather is worked up for each test product for 10 seconds by gently rubbing a moistened pad 35 to 37.7C (95 to 100F) made of soft non-woven cotton cloth in each product.

c) The lathered pads are then massaged slowly but firmly over the cheek area using a counter-circular motion with a pad in each hand, washinq for 60 seconds then 2s rinsinq with running water 35 to 37.7C (95 to 100F) for 10 seconds. This procedure is repeated a second time to equal a two-minute wash treatment. The face is then rinsed for 60 seconds with warm water and patted dry using soft disposable terry towels.

Evaluation and Scoring System ~

a) Panelist self-assessment of facial skin condition is conducted once during the study.
3s ~ 868 b) Panelists will assess their facial condition based on a global evaluation of appearance and feel of skin, comparing both left and right sides of the face.

c) Trained assessors also assess the skin condition using a grade score scale ranging from 0 to 2.5;
independent parameters of evaluation will include softness and feel, degree of dryness, erythema and roughness or the face.

d) Panelists and trained assessors assess both sides of their face and the same hand at all times. The inside forearm of the opposite arm will represent a reference control site for softness.

Data and Statistics The raw data scores are analysed employing a paired t-test and parametric statistical design.

A half face test was conducted as described above on 35 panelists with "normal" skin types to compare the formulation of the invention and a commercial liquid soap.
After one week screening period, the test period consisted of 8 wash treatments over a 4 day span with 9 evaluations done. The first evaluation was made prior to the first wash treatment and the ninth evaluation was made on the morning of the fifth day. The panelists have refrained from the use of anything but water on their faces during the study. Evaluations of various attributes were made by one expert judge and each panelist over the test period. -The top line results of this study are summarized in Table VI. The table indicate those evaluations for which 3s statistically significant differences (with 95%

-~ 2~9~LS86~3 confidence) were detected for each of the eXpert judge and panelist questions.

The composition A specified in Table I was compared to a commercial liquid soap with the following results.

3s -3 V 2(~s8~8 ~o aJ
o h V
.,~
O
~ -~ V
O ., . . . . . . u~
S -, a * ~ a o 3C * * * * *
O * * * * * * u~
a ~ * ~o ~ o *. . . . . . ~
V ~ ,_ a Ir ~ S
1~ > ~.' ~I
o ~: ~
tr ~ ~ o ~: o ~ q~
a u~ o 5~ ~ X a a 2 0 ~ o -,~ ~ o ~ d' P V ~ ~ d' ~
~j 1 ~r~ ~

O c~ o o -,~ a, o *
. -~1 lL Ul ~ * * 'aj ~:
2 5 1 0 * * * *
Q~ * ~ ~r 1 o 1~ V
u~ ~
u~
-- ~ ~
a 1) ~ ~
1 ~ ~ o q~ ~ ~
o ._ ~ , L a~

~ *
3S ~ ~ ~ ~h ~ u~ H * -,1 Ic In the Half Face test against the Commercial Liquid, Composition A is significantly (95% confidence level) preferred by both judges and panelists for overall softness. The judges also rated the Composition A
significantly (95% confidence level) better than the Commercial Liquid for dryness, roughness, tightness, burning, itching and stinging.

Claims

1. A liquid aqueous based skin cleansing composition characterised in that it comprises:

(i) at least 3wt% acyl esters of isethionic acid salts, said esters being predominantly C8-C22 acyl isethionates;

(ii) at least 2wt% of at least one long chain fatty acid having a major proportion of C16 or above; and (iii)at least 2wt% of a moisturizer component;

wherein the weight ratio of said acyl esters to fatty acid ranges from about 1:0.1 to about 1:10, and soap is present in an amount from 0 to 5% by weight of the composition.

2. Composition according to claim 1 comprising additionally at least 2wt% of co-active surfactant.

3. Composition according to claim 2 comprising (i) 3 to 20 wt% said acyl esters of isethionic acid;

(ii) 2 to 15wt% said long chain fatty acid(s);

(iii)2 to 20wt% said co-active surfactant;

(iv) 2 to 15wt% said moisturizer component.

4. Composition according to claim 2 or claim 3 comprising at least 5wt% of said at least one long chain fatty acid, at least 5wt% of said co-active surfactant and at least 5wt% of said moisturizer component.

5. Composition according to claim 1 wherein the acyl esters of isethionic acid comprise at least 75% C12 to C18 acyl isethionates.

6. Composition according to claim 1 wherein the said long chain fatty acids comprises a combination of about 45wt% stearic acid and 55wt% palmitic acid.

7. Composition according to claim 2 wherein the co-active surfactant is one or more components selected from the group comprising anionic, nonionic, cationic and amphoteric surfactants.

8. Composition according to claim 7 wherein the co-active surfactant includes an anionic surfactant and is selected from the group comprising alkyl sulfates, alkyl ether sulfates, alkyl ether sulfonates, sarcosinates, sulfosuccinates, taurates and combinations thereof.

9. Composition according to claim 7 wherein the co-active surfactant includes an amphoteric surfactant and is selected from the group comprising alkylbetaines, amidopropyl betaines, amidopropoyl sultaines and combinations thereof.

10. Composition according to claim 2 wherein the weight ratio of the said acyl esters of isethionic acid to the said co-active surfactant lies in the range of from about 20:1 to about 1:1.

11. Composition according to claim 1 wherein the said moisturizer component is selected from the group comprising liquid water-soluble polyols, glycerin, propylene glycol, sorbitol, polyethylene glycol, ethoxylated/propoxylated ethers of methyl glucose and ethoxylated/propoxylated ethers of lanolin alcohol, and mixtures thereof.

12. Composition according to claim 1 comprising 1 to 7wt%
sodium isethionate.

13. Composition according to claim 1 having a viscosity at a shear rate of 1s-1 of from about 100cps to about 30,000 cps.