EP0575440A1 - LOW pH MILD PERSONAL CLEANSING BAR. - Google Patents

Abstract

This invention is a mild personal cleansing bar comprising: from about 20 % to about 50 % lathering mild synthetic surfactant and from about 5 % to about 50 % of magnesium soap; wherein the ratio of said lathering mild synthetic surfactant to said soap is from about 10:1 to about 0.4:1; said bar having a pH of from about 6.5 to about 8.5 in a 1 % aqueous solution at 25 DEG C.

Description

LOW PH MILD PERSONAL CLEANSING BAR

TECHNICAL FIELD

This invention relates to mild personal cleansing bars and to processes of making them.

BACKGROUND OF THE INVENTION Personal cleansing with mild surface-active cleansing bar preparations has become a focus of great interest. The processa- bility of such bars has also become a focus of great interest. The smear properties of such bars have become a focus of even greater interest. Some of the problems associated with mild bars comprised of synthetic detergents are bar processability, firmness, smear and mildness. The problems of formulating such bars are not limited to the performance characteristics of the finished bars. Most bars which are made with certain mild surfactants are very dif- ficult to fabricate.

In contrast, the fabrication of relatively pure "soap" bars is .a well-worked-out engineering procedure involving milling, plodding and molding. Coco/tallow soap becomes quite plastic when warmed and can be easily plodded and molded under relatively low pressures.

Most synthetic detergents and detergent-filler combinations do not become plastic and the machinery for fabrication must be specially designed. See U.S. Pat. No. 2,678,921, J.A.V. Turck. Jr., issued May 18, 1954. Ideal processing should be fast and problem free in terms of milling, plodding and molding toilet bar formation. Most mild bar processings fall short in this respect. The development of soap-synthetic bars dates back to World War II. U.S. Pat. No. 2,432,169, Hoyt, describes a bar having soap and alkyl benzene sulfonate as the active and a substantial proportion of corn starch as a binder; and U.S. Pat. 2,988,511, Mills and Korpi, issued June 13, 1961, describes a nonsmearing bar comprising alkyl glyceryl ether sulfonate, sodium and magnesium soaps and binder. U.S. Pat. No. 2,982,735, Blinka and Grounds, Jr, issued May 2, 1961, discloses a detergent milled bar com¬ prising soap, anionic detergent and starch.

U.S. Pat. No. 2,781,321, Mayhew et al . , issued Feb. 12, 1957, discloses (Example 19) a 50% Mg stearate all purpose detergent bar with 20% gum, etc. The surfactant system includes dodecylbenzene sulfonate in Examples 26-30, which is a relatively harsh sur¬ factant. STPP is used at levels of 10-15% in Mayhew et al.'s examples.

U.S. Pat. No. 3,070,547, Chaffee, issued Dec. 25, 1962, also discloses a potassium synthetic soap-synthetic bar containing magnesium soap. There appears to be no free fatty acid in the Chaffee exemplified bars, and the pH's of his surfactant systems used in those examples are not disclosed, but are normally rela¬ tively high.

U.S. Pat. No. 2,987,484, Lundberg and Blinka, issued June 6, 1961, discloses a closed die injection molded detergent bar comprising alkyl glyceryl ether sulfonate and acyl isethionate. Some other uses and procedures for making alkyl glyceryl ether sulfonate are disclosed in U.S. Pat. Nos.: 2,094,489, Hulter, issued Sept. 28, 1937; 2,427,576, Smith, issued Sept. 16, 1947: 2,427,577, Smith, issued Sept. 16, 1947; 2,989,547, Whyte, issued June 20, 1961; 2,999,068, Pilcher et al . , issued Sept. 5, 1961; and 3,024,273, Whyte et al ., issued Mar. 6, 1962, all of said patents incorporated herein by reference.

It is noted that surfactant mildness can be measured by a skin barrier destruction test which is used to assess the irri- tancy potential of surfactants. In this test the milder the surfactant, the less the skin barrier is destroyed. Skin barrier destruction is measured by the relative amount of radio-labelec water (3H-H 0) which passes from the test solution through the skin epidermis into the physiological buffer contained in the diffusate chamber. This test is described by T. J. Franz in the J. Invest. Dermatol., 1975, 64, pp. 190-195; in U.S. Pat. No. 4,673,525, Small et al., issued June 16, 1987, and in copending U.S. Pat. Application Ser. No. 294,832, Small et al . , filed Jan. 9, 1989, incorporated herein by reference.

U.S. Pat. No. 2,894,912, Geitz, issued July 14, 1959, for "Isethionate Detergent Bar," discloses a detergent bar consisting essentially of from 30-70% of water-soluble alkali metal detergent salts of esters of isethionic acid with mixed aliphatic fatty acids having from 6 to 18 carbon atoms and an iodine value of less than 20, of which mixed acids at least 75% have from 12 to 18 carbon atoms and up to 25% have from 6 to 10 carbon atoms, from 2-10% of at least one water-soluble suds-boosting detergent salt selected from the group consisting of alkali metal and organic amine higher aliphatic fatty alcohol sulfates, alkyl aryl sul- fonates, and higher aliphatic fatty acid taurides, from about 1% to about 9% water, from about 2.5% to about 25% of water-soluble higher fatty acid soap, and from 10-40% of at least one higher fatty acid having from about 12 to about 25 carbon atoms as a binder and plasticizer, said bar having a pH within the range from 6 to 8, measured as a 10% aqueous solution of the bar composition at 35^βC. No magnesium soap is used.

U.S. Pat. No. 4,180,470, Tokosh et al . , issued Dec. 25, 1979, discloses a method for making improved 30-70% acyl isethionate detergent bars with from 2-6% of sodium alkoxy hydroxy propane sulfonate (a synonym for alkyl glyceryl ether sulfonate) with alkyl chains of from 8 to 22 carbon atoms in conjunction with a small amount of sodium chloride. Ci8 alkyl glyceryl ether sul- fonate at 5% is used in an example. The added alkyl glyceryl ether sulfonate and salt are used to improve bar wear rate without adversely affecting its lathering characteristics.

U.S. Pat. No. 4,234,464, Morshauser, issued Nov. 18, 1980, for "Detergent Bar Composition and Binder Therefor," discloses a detergent bar in Example 6 which comprises: 45% sodium cocoyl isethionate, 5% alkyl amide, 37.5% stearic acid, 5.0% hydrogenated tallow glycerides, and 1% Polymer JR. Morshauser teaches that his detergent bars can contain up to 5% soap "without substantial detriment."

U.S. Pat. No. 4,012,341, Orshitzer et al., issued Mar. 15, 1977, for a "Unique All Synthetic Detergent Shampoo Bar," dis- closes a bar comprising a mixture of anionic and nonionic deter¬ gents. The Examples are primarily based on sodium lauryl sulfate, which is an unacceptably harsh primary surfactant for the present invention.

U.S. Pat. No. 3,761,418, Parran, Jr., issued Sept. 25, 1973, for "Detergent Compositions Containing Particle Deposition Enhanc¬ ing Agents," discloses detergent compositions including a bar, whose main surfactant is alkyl sulfate, which is unacceptable for the mild skin cleanser of the present invention.

Major drawbacks of most synthetic surfactant toilet bar formulations are harshness, poor lather, poor smear, and poor processability due to stickiness. The use of high sudsing anionic surfactants can yield acceptable lather volume. Unfortunately, the highest sudsing anionic surfactants are, in fact, poor in processability. While some prior art mild blends of sodium coco- nut/tallow alkyl glyceryl ether sulfonate (AGS) are relatively good in lather potential, they are not so easy to process because of their stickiness or hygroscopicity. It will be appreciated that processability, firmness, smear, mildness, lather, and rinsability make surfactant selection for mild personal cleansing bars a delicate balancing act. Thus, it will be appreciated that rather stringent requirements for formulating mild personal cleansing bars limit the choice of surfactants, and final formu¬ lations represent some degree of compromise. Mildness is often obtained at the expense of processability, effective cleansing, lathering, or rinsing, or vice versa. Processability is often obtained at the expense of smear.

Needless to say, a superior processable mild personal cleansing bar formulation with good mildness, good smear, good lather potential and good rinsability is difficult to formulate. OBJECTS OF THE INVENTION

An object of the present invention is to provide a stamped, mild personal cleansing bar which has improved processability. Another object of the present invention is to provide a mild bar with excellent smear.

Yet another object is to formulate a mild personal cleansing bar with a relatively low level of free fatty acids to improve bar 5 smear and bar firmness.

Other objects will become apparent from the detailed de¬ scription below.

SUMMARY OF THE INVENTION

This invention is a mild personal cleansing bar comprising: 0 from about 20% to about 50% lathering mild synthetic surfactant and from about 5% to about 50% of magnesium soap; wherein the ratio of said lathering mild synthetic surfactant to said soap is from about 10:1 to about 0.4:1; said bar having a pH of from about 6.5 to about 8.5 in a 1% aqueous solution at 25'C. 5 DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a mild personal cleansing bar made from a mix of from about 20% to about 50% of a lathering mild synthetic detergent surfactant and from about 5% to about 50%, preferably from about 10% to about 45%, magnesium soap. The mild 0 personal cleansing bar has a pH of from about 6.5 to about 8.5. The pH of the bar is preferably from 7 to 8-, and is preferably adjusted with a carboxylic acid. The pH is measured as a 1% aqueous solution at about 25'C.

The ratio of lathering mild synthetic surfactant to the ₅ magnesium soap is from about 10:1 to about 0.4:1, preferably from about 5:1 to about 0.5:1, more preferably from about 4:1 to about 0.6:1.

The term "lathering mild synthetic surfactant" as used herein means any surfactant which lathers at least about as well as the _Q "mild standard alkyl glyceryl ether sulfonate (AGS)," as defined herein, which contains a substantial amount of C1 and C14 alkyl chains, specifically about 68% C12; 25% C14; and 7% Ciβ AGS.

A "non-lathering, non-soil-load-diluent, surfactant" is defined as a surfactant which has a "low" lather on the order of a 5 16-C18 alkyl glyceryl ether sulfonate, and other C16-C18 syn¬ thetic surfactants, e.g., C16-C18 alkyl sulfates, etc. These surfactants do not contribute to the lather in any appreciable way, but they also do not detract from the lather in any significant way. They are, however, especially effective in improving the ability of the bar to have a good grade in the Flex Test as described more fully hereinafter. They also are useful in improving the smear characteristics of the bars.

The terms "soil load diluent" and "hydrophobic material" as used herein are synonymous and mean any diluent which is a soil load on the order of free fatty acid, paraffin wax, fatty alcohol. or triglyceride. Some of these materials, like paraffin wax, are very effective in improving the Flex Test grades. Other materials, like free fatty acid, help plasticize the formula for processability.

The magnesium (Mg) soap can be made by using selected fatty matter (free fatty acids and soaps) having an Iodine Value of from zero to about 50, preferably below 15, and more preferably from about zero to about 3. The titer (in ^*C) can be as low as about 15, however, the preferred fatty matter of the soap and free fatty acid have a titer of from about 60 to 80, preferably from about 35 to 75, and more preferably from about 50 to about 70.

The chemical properties of some preferred pure saturated acids are set out below in the Pure Acid Table.

Pure Acid Table

Palm Kernel Acid Table (Typical)

Acid Chain Length Wt.% Saturated:

Octanoic

Decanoic

Laurie

Myristic

Palmitic

Stearic Unsaturated:

Oleic

Linoleic

Iodine Value:

Saponification Value:

Titer, ^βC (Fatty Acid):

Palm Kernel Acid, Coconut Acid and Tallow Acid Tables show some chemical properties of those acids.

Coconut Acid T e T l

The free fatty acid (and other soil load diluents) in the mild personal cleansing bar of the present invention can be surprisingly low. The Mg soap to FFA ratio can be from about 50:1 to about 0.5:1, preferably from about 30:1 to about 1:1, and more preferably from about 15:1 to about 2:1. The level of FFA is preferably from about 1% to about 10%, preferably from about 2% to about 9%, more preferably from about 3% to about 8%, of the bar.

The hydrophobic material (soil load diluents) can be present in the bars of this invention at a level of from zero up to about 40%, but is preferably used at a level of from about 5% to about 20%. The other hydrophobic material including free fatty acids containing from about 8 to about 18 carbon atoms; mono-, di-, and triglycerides; fatty alcohols containing from about 8 to about 18 carbon atoms; and mixtures thereof; wherein said composition contains about 25% maximum of said waxes and about 15% maximum of said other hydrophobic material. Triglycerides (Cs-Ciβ acyl chain) can be used up to about 10% without adversely affecting acceptable lather performance.

The preferred hydrophobic material is a wax having a melting point (M.P.) of from about 120^*F to about 185^*F (49^β-85^βC), preferably from about 125'F to about 175^βF (52'-79'C). A pre¬ ferred paraffin wax is a fully refined petroleum wax having a melting point ranging from about 130^*F to about 140'F (49^β-60^βC). This wax is odorless and tasteless and meets FDA requirements for use as coatings for food and food packages. Such paraffins are readily available commercially. A very suitable paraffin can be obtained, for example, from The Standard Oil Company of Ohio under the trade name Factowax R-133.

Other suitable waxes are sold by the National Wax Co. under the trade names of 9182 and 6971, respectively having melting points of 131'F and 130'F (-55^*C).

The paraffin preferably is present in the bar in an amount ranging from about 5% to about 20% by weight. The paraffin ingredient is used in the product to impart skin mildness, plas¬ ticity, firmness, and processability. It also provides a glossy look and smooth feel to the bar.

The paraffin ingredient is optionally supplemented by a microcrystalline wax. A suitable microcrystalline wax has a melting point ranging, for example, from about 140^βF (60^βC) to about 185^*F (85^*C), preferably from about 145'F (62'C) to about 175°F (79^βC). The wax preferably should meet the FDA requirements for food grade microcrystalline waxes. A suitable micro¬ crystalline wax is obtained from Witco Chemical Company under the trade name Multiwax X-145A. The microcrystalline wax preferably is present in the bar in an amount ranging from about 0.5% to about 5% by weight. The microcrystalline wax ingredient imparts pliability to the bar at room temperatures.

The non-soil-load, surfactant diluent can be used at a level of from 0% to about 40%, preferably from about 5% to about 40%. and more preferably from about 10% to about 35%. The latter level range is highly preferred for Flex Test mildness.

The water level is from about 2% to about 15%, preferably from about 4% to about 10%. The total non-surfactant electrolyte (organic and inorganic) level is from about 1% to about 10%, preferably from about 2% to about 8%, more preferably from about 2% to about 5%, by weight of the bar. Numerous examples of surfactants are disclosed in the patents incorporated herein by reference. They include alkyl sulfates, anionic acyl sarcosinates, methyl acyl taurates, N-acyl gluta- mates, alkyl sulfosuccinates, alkyl phosphate esters, ethoxylated alkyl phosphate esters, trideceth sulfates, protein condensates, mixtures of ethoxylated alkyl sulfates and alkyl amine oxides, betaines, sultaines, and mixtures thereof. Included in the sur¬ factants are the alkyl ether sulfates with 1 to 12 ethoxy groups, especially ammonium and sodium lauryl ether sulfates.

Alkyl chains for these surfactants are C8-C 2. preferably 12-C1 for lathering mild surfactants, and C16-C18 for non- lathering non-soil-load diluents.

The term "alkyl glyceryl ether sulfonate" as used herein means, in general, a mixture of alkyl glyceryl ether sulfonate

(AGS) surfactants having alkyl chains of from 8-22 carbon atoms, preferably from 10-20 carbon atoms, and more preferably from 12-14 carbon atoms.

Alkyl glyceryl ether sulfonates are derived from corres¬ ponding ethers consisting of straight alkyl chains which are in turn derived from their corresponding synthetic or natural alcohols.

Commonly assigned U.S. Pat. No. 4,673,525, Small et al . , supra, discloses a mild alkyl glyceryl ether sulfonate surfactant based mild personal cleansing bar comprising alkyl glyceryl ether sulfonate. The mild personal cleansing bars of this invention exhibit improved processability over the exemplified mild personal cleansing bars disclosed in Small et al . In other words, the improved bars of this invention also exhibit a processability improvement over comparable AGS soap bars. The bars of this invention are also better in terms of bar firmness and smears. Alkyl glycosides and methyl glucose esters are preferred mild nonionics which may be mixed with at least one of said mil anionic or amphoteric surfactants in the compositions of this invention.

A preferred ingredient is acyl isethionate. Acyl isethi- onates are aliphatic higher fatty acid esters of an alkali metal isethionic acid salt and can be defined by the following general formula: RCOOCH2CH2SO3M wherein R is an aliphatic radical or mixed aliphatic radical of a higher fatty acid or mixture thereof, having from about 6 to about 20 carbon atoms, preferably from about 8 to about 18 carbon atoms, e.g., cocoyl or an approximately equivalent distribution of chain lengths, the longer chains (16 and 18) being more preferred as non-lathering, non-soil-load diluents and medium chain (C12-C14) being more preferred as lathering synthetic surfactants; and wherein M is an alkali metal cation such as sodium, potassium, or ammonium, or an organic amine base such as triethanolamine, triisopropanolamine, diethanolamine and ethanolamine. The preferred cation in the AGS and the acyl isethionate salts is sodium.

A preferred milled bar for Flex Test mildness comprises: (1) from about 5% to about 25%, preferably from about 10% to about 20%, of C16-C18 alkyl (chain) sulfates and (2) from about 5% to about 50%, preferably from about 10% to about 30% magnesium soap by weight of the soap bar. E.g., Example 7 disclosed hereinbelow. Lathering mild synthetic surfactants are also required in this preferred bar. The ratio of the alkyl sulfates to magnesium soap can be from about 3:1 to about 1:6, preferably from about 1:2 to about 1:4. This non-soil-load, non-lathering, synthetic sur¬ factant diluent is a surprisingly and unexpectedly excellent or superior diluent for lathering ultra mild synthetic surfactants, e.g., alkyl glyceryl ether sulfonate and/or cocoyl isethionate in personal cleansing bar compositions. The synthetic surfactant diluents provide a surprisingly acceptable improvement in bar processability, while not significantly impairing bar mildness or the desirable physical characteristics of the bars.

The C16-C18 alkyl sulfates are derived from corresponding saturated straight chain alcohols. The C16-C18 alkyl sulfates, as defined herein, comprise said C16-C18 alkyl chains at a level of at least about 90%, preferably about 93%, and more preferably about 97%. In general, the ratio of Ci6 to Cis can range from about 4:1 to about 1:4 by weight. A commercially available

Ciδ-Cis alkyl sulfate is SIPON^® EC-Ill (formerly SIPEX^® EC-Ill), sodium cetearyl sulfate, which is approximately 60% Cie and 36%

Ci8- SIPON® EC-Ill is sold by Alcolac Company, Baltimore, MD 21226. Another source is Henkel Corp., Ambler, PA 19002.

Henkel's sodium cetearyl sulfate, LANETTE E, is an estimated

50-50% Ciδ-Cis alkyl sulfate sold as an emulsifier.

The percentages, ratios, and parts herein are on a total composition or surfactant weight basis, unless otherwise speci- fied. All formulae, levels and ranges herein are approximations unless otherwise specified. Some preferred percentages and ratios are described below.

The lathering synthetic surfactant comprises from 20% to 50% by weight of the bars of this invention. A preferred bar com- prises: about 25% to 45% lathering mild synthetic surfactant; about 15% to 20% of non-soil-load synthetic surfactant diluent, e.g., cetearyl sulfate; about 10% to 50% magnesium soap; and about

1% to 10%, preferably 2% to 9%, free fatty acid; about 0% to 8%, preferably 0.2% to 2%, polymeric skin feel aid; and 2% to 15%, preferably 4% to 10%, water.

The bars of the present invention comprise a soil load diluent (FFA, wax, etc.) to lathering mild synthetic surfactant ratio of from 0.1:1 to 1:1, preferably from 0.2:1 to 0.9:1.

The bars of the present invention comprise a soil load diluent to a non-soil-load diluent (including Mg soap) ratio of from 0.1:1 to 1:1, preferably from 0.2:1 to 0.9:1, and without Mg soap the ratio is 0.4:1 to 30:1.

The bars of the present invention comprise a lathering synthetic surfactant to a non-soil-load diluent (with Mg soap) ratio of from 0.2:1 to 3:1, preferably from 0.3:1 to 2:1, and without Mg soap the ratio is 0.5:1 to 35:1.

The bars of the present invention comprise a magnesium soap to lathering synthetic surfactant ratio of from 1:10 to 1:0.4. preferably from 1:5 to 1:0.5, more preferably from 1:4 to 1:0.6. The bars of the present invention comprise a magnesium soap to total synthetic surfactant(s) (lathering + diluent) ratio of from 0.1:1 to 3:1, preferably from 0.2:1 to 2:1, and more prefer¬ ably from 0.3:1 to 1.5:1.

The bars of the present invention comprise a magnesium soap to free fatty acid ratio of from 50:1 to 0.5:1, preferably from 30:1 to 1:1, more preferably from 15:1 to 2:1.

The bars of the present invention comprise a magnesium soap to a soil load diluent (FFA, wax, etc.) ratio of from 0.3:1 to 5:1, preferably from 0.4:1 to 4:1.

For improved smears, it should be noted that when the mag- nesium soap level is low, e.g., 10% or less, and when the level of the total synthetic surfactant(s) to magnesium soap is more than

5:1, the water level of the bar should be from about 2% to about

7%, preferably from about 2.5% to about 6% for improved smear.

More than one lathering synthetic surfactant can be used. E.g., from about 2% to about 25%, preferably from about 3% to about 20%, more preferably from about 4% to about 16%, of very high lather enhancing surfactant, e.g., sodium lauroyl sarcosinate can be used with AGS, as shown in the Examples herein.

Other bar ingredients are selected from: non-lathering diluent surfactants, magnesium soap, soil load diluents, polymeric skin feel aids, moisturizers, fillers, etc.

The mild personal cleansing bars can also have about 0-8%, preferably about 0.2-2%, polymeric skin feel aid if present.

A preferred bar of this invention can comprise about 0.1% to 5%, more preferably 0.2% to 2%, of a suitably fast hydrating cationic polymer. The polymers have molecular weights of from about 1000 to about 3,000,000. A preferred one is selected from cationic guar gums having a molecular weight range of 2,500- 350,000. The cationic polymer (skin conditioning agent) is selected from the group consisting of:

(I) cationic polysaccharides;

(II) cationic copolymers of saccharides and synthetic cationic monomers, and (HI) synthetic polymers selected from the group consisting of: (A) cationic polyalkylene imines (B) cationic ethoxy polyalkylene imines, and

(C) cationic poly[N-[-3-(dimethylammonio)propyl]-N'-[3- (ethyleneoxyethylene dimethylammonio)propyl]urea dichloride]. Specific examples of members of the cationic polysaccharide class include the cationic hydroxyethyl cellulose JR 400 made by Union Carbide Corporation; the cationic starches Stalok^® 100, 200, 300 and 400 made by Staley, Inc.; the cationic galactomannans based on guar gum of the Galactasol 800 series by Henkel , Inc. and the Jaguar Series by Celanese Corporation.

Examples of members of the class of copolymers of saccharides and synthetic cationic monomers include those composed of cel¬ lulose derivatives (e.g., hydroxyethyl cellulose) and N,N-di- allyl,N-N-dialkyl ammonium chloride available from National Starch Corporation under the trade name Celquat.

The cationic synthetic polymers useful in the present in¬ vention are cationic polyalkylene imines, ethoxypolyalklene imines, and poly[N-[-3-(dimethylammonio)propyl]-N'-[3-(ethylene- oxyethylene dimethylammonio)propyl]urea dichloride] the latter of which is available from Miranol Chemical Company, Inc. under the trademark of Miranol A-15, CAS Reg. No. 68555-36-2.

Preferred cationic polymeric skin conditioning agents of the present invention are those cationic polysaccharides of the cationic guar gum class with molecular weights of 1,000 to 3,000,000. More preferred molecular weights are from 2,500 to

350,000. These polymers have a polysaccharide backbone comprised of galacto annan units and a degree of cationic substitution ranging from about 0.04 per anhydroglucose unit to about 0.80 per anhydroglucose unit with the substituent cationic group being the adduct of 2,3-epoxypropyltrimethyl ammonium chloride to the natural polysaccharide backbone. Examples are JAGUAR C-14-S, C-15 and C-17 sold by Celanese Corporation. In order to achieve the benefits described in this invention, the polymer must have characteristics, either structural or physical which allow it to be suitably and fully hydrated and subsequently well incorporated into the soap matrix. Other ingredients of the -present invention are selected for the various applications. E.g., perfumes can be used in formu¬ lating the skin cleansing products, generally at a level of from about 0.1% to about 1.5% of the composition. Alcohols, hydro- tropes, colorants, and fillers such as talc and clay, can also be used. Preservatives, e.g., sodium ethylenediaminetetraacetate (EDTA), generally at a level of less than 1% of the composition, can be incorporated in the cleansing products to prevent micro¬ biological growth. Antibacterials can also be incorporated, usually at levels up to 1.5%.

A preferred bar of the present invention can contain from about 0.5% to about 4%, preferably from about 2% to about 3.5%, trisodium phosphate.

The following patents disclose or refer to such ingredients and formulations which can be used in the mild personal cleansing bars of this invention, and are incorporated herein by reference:

The magnesium soaps can be added as is, or made in situ, e.g., via adding a base, e.g., Mg(0H)2, to convert free fatty acids in the composition mix.

In another preferred (suitable) method of preparing bars of the present invention, the synthetic detergent, neutralized with a solution of an alkali metal hydroxide or carbonate, to which the salting-out electrolyte has been added (if insufficient electro- lyte will be formed in situ during the neutralization step and in other steps of the process), is introduced into a suitable mixer, such as a soap crutcher. Some water can then be added to improve fluidity, and a sodium soap, preferably as soap containing about

30% water, is added. These ingredients are mixed and then an appropriate amount of water-soluble alkaline earth metal salt, such as magnesium sulfate or chloride, or calcium chloride, is added to convert a portion of the water-soluble soap to water- insoluble soap, sodium salting-out electrolyte being formed as by-product. In a preferred method, the magnesium soap is made before the synthetic surfactant is added to the mix. Mixing is then continued to insure the equilibrium in the formation of the magnesium soap is attained. Desirable adjustments in water- soluble soap content may, of course, be made after the magnesium soap has been formed.

Two Preferred Processes for Making a Preferred Mild Personal Cleansing Bar

I. Crutching - Neutralization

1. Add predetermined quantity of AGS paste at 65^*C (150°F) to the crutcher.

2. Outside the crutcher, add the predetermined quantity of NaCl and Na2Sθ4 to enough hot water at 75'C (167'F) to get the final crutcher moisture up-to 50%, accounting for all other raw material moisture content. After dissolution of the electrolytes in the hot water, add the mixture to the crutcher. 3. Turn the agitator and recirculation pump (optional) on and maintain a crutcher temperature of 75-85^βC (167-185^βF) by adjusting steam and water valves.

4. Add predetermined amount of Tiθ2 powder to the crutcher.

5. Add predetermined amount of Mg(0H)2 powder at ambient temperature to the crutcher. A slurry of this material may also be used. Mix until powder is visibly dis¬ tributed fully.

6. Add predetermined amount of fatty acid to the crutcher to produce magnesium soap. Ideally, the acid should be added in a molten form at 75-85^βC (167-185^βF). If added as a powder, continue mixing until powder is visibly melted. 7. Add predetermined quantity of sarcosinate solution at ambient temperature to the crutcher. Allow crutcher to return to target temperature.

8. Add predetermined quantity of molten paraffin at 75-85'C (167-185'F) to the crutcher. If flakes of paraffin are added, allow paraffin to melt completely.

9. Allow contents of crutcher to completely mix and react until the pH of the crutcher reaches a target of 7.3-8.0, while maintaining the crutcher temperature at 75-85'C (167-185'F). This typically takes 20-40 minutes.

10. Add predetermined quantity of excess fatty acid, at a temperature consistent with the previous fatty acid addition. Allow the crutcher to mix for an additional 10 minutes.

II- Crutching - Ion Exchange

1. In the crutcher, put the required amounts of soap, fatty acids and triglyceride at 82-88'C (180-190'F) and mix until homogeneous, approximately 10 minutes.

2. Solubilize the gCl2 in water and add to the crutcher. Continue to mix at 82-88'C (180-190'F) until reaction is complete, approximately 10 minutes.

3. Add the liquid sodium lauroyl sarcosinate, the sodium cocoyl glyceryl ether sulfonate, and the amine oxide to the crutcher, maintaining the temperature at 82-88'C (180-190'F). Mix until homogeneous, approximately 10 minutes.

4. Add the desired amount of Polyoxyethylene WSR-35 and mix for 5 minutes.

Drying for Both I. and II.

The crutcher mix is dried and cooled using a combination flash chamber and chill roll or chill belt. The crutcher mix is first heated to approximately 132'C (270'F) by a heat exchanger and then flash dried in a chamber above the chill roll or chill belt. From the flash chamber the hot, dried mix is extruded onto the chill roll or chill belt. The chill belt or chill roll provides a uniform, thin, cool (29-35'C, 85-95'F) product in flake or chip form. Typical moisture for the flake is 2-12%, preferably 6-8%. The ways to regulate the moisture, in the order of prefer¬ ence, are (1) increasing or decreasing steam pressure on the heat exchanger; (2) increasing or decreasing crutcher mix rate to the heat exchanger; and (3) increasing or decreasing crutcher mix temperature to the heat exchanger. Amalgamating

The flakes are weighed and mixed in a batch amalgamator to obtain uniform flake size. Preweighed perfume is added to the flakes and mixed in the amalgamator to obtain the desired finished product perfume level. The perfumed flakes are transferred to the mill hopper or directly to the plodder. Milling (Optional)

The 3-roll soap mills are set up with the first roll at 38°C (100'F) and the other two mills at about 21'C (70'F). The soap is passed through the mills several times to provide a homogeneous mixture of perfume and dried flakes. Plodding and Stamping

The plodder is set up with the barrel temperature at about 21'C (70"F) and the nose temperature at 38-49'C (100-120'F). The ideal plodder is a dual stage plodder that allows use of a vacuum of about 15-25 inches of Hg. The plugs should be cut in 5" sections and stamped with a cold die block using die liquor such as alcohol, if appropriate.

EXAMPLES The following examples and methods are illustrative and are not intended to limit the scope of the invention(s) . The detailed methods of making and purifying generic alkyl glyceryl ether sulfonate per se are disclosed in U.S. Pat. No. 2,988,511, supra. incorporated herein by reference. The percentages, ratios, and parts herein are on a total composition or surfactant weight basis, as indicated, unless otherwise specified. All levels and ranges, temperatures, results etc., are approximations unless otherwise specified.

The mild personal cleansing bars of Examples 1-7 are made using the above preferred crutching neutralization process.

Example 8 is made by adding magnesium chloride to Na soap to for-η the Mg soap by ion exchange before mixing with the synthetic surfactants. Comparative Example A is made similar to the bars of

Examples 1-7, except that sodium hydroxide is used instead of

Mg(0H)2 and is used as a standard for the mildness and smears.

Comparative Example B is the "B" bar and is used as a second standard for the mildness and smears. Comparative Example C is a leading commercial all soap bar and is used as a standard for typical all soap bars. Example 3 is the preferred overall bar for mildness, lather, and smears.

Two bar smear tests are disclosed below, the "Mush Smear 1" and the "Bar Character Smear 2."

Mush Smear "1" Test Procedure Equipment:

1. #2-202C Fisher Brand Hexagonal Polystyrene weighing dishes (4" x 3").

2. #14-366A Fisher Brand Spatula.

3. Balance capable of weighing to two decimal points.

4. 120^*F Temperature Room.

5. Timer. Test Method

1. Label and weigh the number of weighing dishes needed (two weighing dishes per sample, one labeled M for mush dish, one labeled S for soak dish).

2. Weigh the original bar and record the weight. Place bar in preweighed dish labeled S.

3. Add 30 mis room temperature city water to the dish containing the bar prototype (pour water down side of weighing dish). Add 30 mis room temperature city water to the dish containing the control bar. When placing the bars in the dish make sure the bars are not touching the sides of the dishes.

4. Allow bars to soak in weighing dishes at room temperature for 2 hours undisturbed.

5. After 2 hours of soaking, pick bar up carefully and allow to drain into the same dish for 15 seconds. 6. After 15 seconds, invert bar and place in preweighed dish labeled M. 7. Weigh soaked bar and record.

8. Scrape the wet surface or mush from the bar, with a spatula, into the same preweighed dish labeled M, weigh and record. Best results for scraping are seen when the spatula is held loose in hand being careful not to gouge the bar or to scrape too deeply. When the surface of the bar no longer appears to look wet or shiny, scraping is completed. To eliminate variability of scraping from person to person, results from each test will be reported relative to the control placed in that test.

9. Weigh and record the scraped bar.

10. Place the soak dish, the mush dish, and the scraped bar in the 120^*F Temperature Room for water evaporation for 48 hours. 11. After 48 hours, weigh and record the dry weight of the soak dish, the mush dish and the scraped bar.

12. Calculate the surface area of the scraped portion of the bar by measuring (in inches) length times width.

13. Add the number of dry grams of mush (smear) to the number of dry grams of soak. This is the overall result in grams.

All series of testing should include control, and all samples should be run in duplicates. A maximum of 7 products (6 plus a control) can be tested at one time, and an interval of 10 minutes between every 4 samples should be allotted for the addition of water as to not allow any products a lag time for soaking longer than 2 hours.

Bar Character Smear "2" Test 5 ml Smear Test

Equipment

"Alathon" soap dishes Small measuring cylinder Method 1. Wet soap bar to be tested by dipping surface to be soaked in distilled water and shaking off excess water. This procedure leads to more uniform bar smear. 2. Place bar centrally on "-Alathon" dish containing 5 ml of distilled water. Rock dish to break water tension. The Alathon dish was selected as being a standard, readily available (in U.S.) dish with low ridges. 3. Store overnight (approximately 18 hours) in standard con¬ ditions of temperature and humidity (27'C/80'F/80% RH were used). As this test measures the bar's ability to recover as well as absorb water, standard conditions avoid seasonal variations which may occur in uncontrolled laboratory over- night conditions.

4. Next morning, remove bar with a careful vertical lift and invert for judging. Judging

Bar Smear - Each judge grades soap bar smear by fingering the bar and taking into account both types of smear and amount of smear.

Grade Smear Description 10 Excellent

9 Very good smear 8 Good smear (Target)

7 Slightly poorer than desired 6 Marginal but still acceptable 5 Minimum acceptable smear 4 Poor and unacceptable 3 Very poor smear

2 Poorest normally seen 1 Extremely poor smear

Clinical Assessment of the Toilet Bars The clinical test procedure used to evaluate several toilet bar formulations for skin mildness is given below. Mildness Forearm Wash Test Procedure The washings are performed by a technician. Each panelist is assigned a set of 8 products for washings, 4 per arm. The test procedure for each arm is: Protocol

1. Place 3M Micropore surgical tape with 4 precut 3.2 cm diameter holes on the volar forearm. Center tape on the lower inner forearm trying to keep the lower treatment area away from the wrist area.

2. Wet the forearm with warm (35-40'C) water.

3. Wet a nonwoven paper towel (Masslinn Towel, Chicopee Mills, New Brunswick, New Jersey) with warm water. Rub the towel on the appropriate test product using a circular motion for 6 seconds.

4. Rotate the towel at each test site for 10 seconds.

5. Allow lather from the test products to remain on the test site for 90 seconds.

6. Rinse each site with warm water (35-40'C) for 15 seconds.

7. Pat area dry with soft, disposable (BOUNTY^®) paper towel .

8. Wait 2 minutes and repeat above procedure for a second time. 9. This procedure is to be followed 2 times daily, for 4 consecutive days, and 1 time the final day of the study, for a total of 17 washings. Each of the daily visits will be approximately 3 hours apart. A visual inspec¬ tion of each test site is to be made just prior to the second wash procedure of the third day and 3 hours after the final wash of the fifth day. Observable dryness and erythema will be scored at each examination period. 10. The following grading scales are used:

Clinical Test Skin Grading Scales

The forearm skin grading scales reported herein are set out below.

Forearm Grading Scale - Skin Dryness 0 Perfect skin. 1.0 Patches of checking and/or slight powderiness and occasional patches of small scales may be seen. Distribution generalized. 2.0 Generalized slight powderiness. Early cracking or occasional small lifting scales may be present. 3.0 Generalized moderate powderiness and/or moderate cracking and lifting scales. 4.0 Generalized heavy powderiness and/or heavy cracking and lifting scales. 5.0 Generalized high cracking and lifting scales.

Ecze atous change may be present. Powderiness may be present but not prominent. May see bleeding crack.

6.0 Generalized severe cracking. Eczematous change may be present. Bleeding cracks may be present.

Scales large, may be beginning to disappear.

Forearm Grading Scales - Skin Erythema

0 No redness 1.0 Barely detectable redness 2.0 Slight redness 3.0 Moderate redness 4.0 Heavy or substantial redness

5.0 Severe redness 6.0 Extreme redness The term "generalized" as used herein means that more than 50% of the surface area of the forearm exhibits the attribute. Whole unit skin grades reflect generalized condition. Half units are used to represent intermediate conditions.

Flex Test Wash Protocol 1. Wet one sponge under warm, about 37'C (95-100'F) water until completely wet.

2. Squeeze the sponge 3-4 times to remove excess water.

3. Lather the moistened sponge, in a circular motion, directly on the test bar for 10 seconds. 4. Wash the appropriate test areas of the inner volar forearm for 60 seconds (i.e., washing motions of 2-3 circular revolutions per second). 5. Thoroughly rinse the ash area and pat dry with a paper towel (15-second rinse recommended).

6. This procedure is to be followed 3 times daily for 5 consecutive days for a total of 15 washings. Each of the daily wash procedures will be approximately 2 hours apart. A visual inspection of each test site is to be made just prior to the next wash procedure. Observable erythema will be scored at each examination period. The final examination is to be made about 2 hours following the last wash procedure.

7. The following erythema scoring scale is to be used:

0 = no evidence of erythema

1 = slight erythema (spotty and/or minimally perceptible) 2 = moderate erythema (more uniform, pink-red)

3 - marked erythema (uniform, relatively brighter or deeper red) Intermediate 0.5, 1.5, 2.5, and 3.5 increments may also be scored with necessary. 8. Arms are no longer subjected to the washing procedure if a rating of "2" or greater is attained. The score of "2" is assigned for the remainder of the study. 9. Products are statistically compared by examining the number of Grade 2 or higher ratings. The fewer the number of these ratings, the milder the product is judged to be.

In the following Examples, which include magnesium soap, some or all of the magnesium soap can be replaced with other alkaline earth metal soap such as calcium, zinc, aluminum, and other soaps, which are substantially insoluble on the order of magnesium soap.

*Emersol 132 (Emery Industries) is really a mixture of stearate and laurate having a titer of about 55 and a maximum I.V. of 0.5. . x. Ex. 3 Ex. 4

*Lower numbers the better. **Higher numbers the better.

The totals for: lathering mild synthetic surfactant; mag- nesium soap; non-soil-load, non-lathering surfactant; and soil load diluent for Examples 1-4 are as follows:

TABLE 1 Continued

*Emersol 132 (Emery Industries) . 7 Ex. 8

*Lower numbers the better. **Higher numbers the better. N/A = Not available.

The total level of synthetic surfactants in Example 7 is 56%, and the water level is 7.5%; the ratio of Mg soap to total synthetic is 0.18:1. The smears could be improved in Example 7 by lowering the water level to below about 7%. Note that Example 5 which has a total synthetic of 56.6% and a Mg soap to total synthetic ratio of 0.22:1 but has a higher Mg soap level, 12.8% vs. 10%, has a better smear, notwithstanding equal water levels for Examples 5 and 7.

For improved smears, it should be noted that when the mag¬ nesium soap level is low, e.g., 10% or less, and when the level of the total synthetic surfactant(s) to magnesium soap is more than 5:1, the water level of the bar should be from about 2% to about 7%, preferably from about 2.5% to about 6% for improved smear.

TABLE 2

Comparative Example A is an ultra mild bar having fairly good smear, about the same as the "B" bar, a mild, commercially avail¬ able, soap/synthetic bar. Comparable mild bars of this invention, e.g., Examples 1-6 and 8 have improved smears over Example A, as well as the Standard Comparative Example B, which is the "B" bar. Comparative Example C is a leading pure soap bar to show the superior mildness of the bars of this invention over it.

*Lower numbers the better. **Higher numbers the better.

Summary of AGS Surfactant Chain Lengths Used in Examples % Chain Length Distribution % Cχ6-Ci8

Example £1 £l4 C_i6 Cjjj Chain Length 1-8 68 25 7 - 7 A* 58 21 10 9 19 ^♦Comparative Example A.

The average smears for Examples 1-6 are better than Compara¬ tive Example A, notwithstanding the higher AGS alkyl chain distri¬ bution, more Cχ6 and 9% Cχ8 on an AGS weight basis.

Mildness Test Results Flex Test*

Erythema

Ex. C 2.42

Ex. 4 1.18

Ex. 3 0.90 Ex. 7 0.68

Ex. B 0.65-1.29

Ex. 8 1.59 Previous Test

Ex. A 1.09 Previous Test

In the above Flex Test Erythema Results, the lower the erythema, the milder the personal cleanser. Comparative bar Example C, a leading all soap bar, has the highest erythema grad of 2.42. Examples 4, 3, and 7 have erythema grades comparable t the "B" bar which show grades of from about 0.65 to about 1.29, the low and the high of four "B" bar grades. The erythema grade for 4, 3, and 7 are, respectively, 1.18; 0.90; and 0.68. Th erythema grades for Example 8 and Comparative Example A are bette than the all soap bar, Example C, and are close to the "B" bar.

The "B" bar results 0.65-1.29 are the low and high of fou side-by-side Flex Tests for Examples C, 4, 3, and 7. The Fle Test results for Examples 8 and A, while not part of the Exampl C, 4, 3, and 7 test series, are shown to suggest that Example 8 is not as good as "B," but milder than the all soap bar, Comparativ Example C. It is noted that Example 8 has less preferred fatty matter, specifically a lower titer (37) and a higher Iodine Value (38) than Examples 4, 3, and 7. The titers and I.V.'s for Examples 4, 3, 7, and 8 are:

Referring to Table 1, Example 8, however, has an excellent Smear 2 of 8.

Forearm Clinical*

Redness Dryness

Ex. 8 1.18 1.68

Ex. A 1.19 1.66

Ex. A 1.16 1.70

Ex. B 1.70 S 2.22 S

Ex. 2 1.37 1.44 Ex. B 1.69 S 1.63 S

^♦Lower numbers the better. S = Significance at 90-95% confidence. Forearm Clinical results suggest that Examples 8, 9, and 2 are all better than "B" for both Redness and Dryness. Examples 8 and A are about equal, and A is significantly better than B. Example 2 is also significantly better than "B." . Example 2 also has superior smears over "B" as shown in Tables 1 and 2; Average Smears 1 are 0.98 for Example 2 vs. 2.55 for "B," which shows a significant advantage for Example 2. Smears 2 are 7.5 for Example 2 vs. 7.0 for "B," which is a slight advantage for Example 2. A panel of experts compared some sensory characteristics of Example 2 with those of the "B" bar. The results are: Example 2 has sensory characteristics, tightness, smoothness, and softness, comparable to the "B" bar. The tightness result is surprising in view of the presence of 33% magnesium soap in Example 2.

WHAT IS CLAIMED IS:

Claims

1. A mild personal cleansing bar comprising: from about 20% to about 50% lathering mild synthetic surfactant and from about 5% to about 50% of magnesium soap; wherein the ratio of said lathering mild synthetic surfactant to said soap is from about 10:1 to about 0.4:1; said bar having a pH of from about 6.5 to about 8.5 in a 1% aqueous solution at 25'C.

2. The mild personal cleansing bar of Claim 1 wherein said magnesium soap is from about 10% to about 45%; said ratio is from about 5:1 to about 0.5:1; said bar having a water level of from about 2% to about 15%; and said pH is from about 7 to 8.

3. The mild personal cleansing bar of Claim 1 or 2 wherein said lathering mild synthetic surfactant to said Mg soap ratio is from about 4:1 to about 0.6:1 and said water level is from about 4% to about 10%; preferably wherein said bar contains from about 1% to about 10% free fatty acid and said magnesium soap and said free fatty acid have a ratio of from about 50:1 to about 0.5:1 and wherein said soap and fatty acid has a titer of from 15 to 80 and an Iodine Value of from zero to about 50.

4. The mild personal cleansing bar of Claim 1, 2, or 3 wherein said bar contains from about 2% to about 9% free fatty acid and said magnesium soap and said free fatty acid have a ratio of from about 15:1 to about 2:1 and said Iodine Value is from zero to about 15 and said titer is from about 40 to about 75.

5. The mild personal cleansing bar of Claim 1, 2, 3, or 4 wherein said magnesium soap is made by either ion exchange or by neutralization.

6. The mild personal cleansing bar of Claim 1, 2, 3, 4, 5, or 6 wherein said bar contains electrolyte at a level of from about 1% to about 10%; preferably from about 2% to about 5%.

7. The mild personal cleansing bar of Claim 1, 2, 3, 4, 5, or 6 wherein said bar contains from 1% to about 40% of hydrophobic material selected from the group consisting of waxes; and other hydrophobic material including free fatty acids containing from about 8 to about 18 carbon atoms; mono-, di-, and triglycerides; fatty alcohols containing from about 8 to about 18 carbon atoms; and mixtures thereof; wherein said composition contains about 25% maximum of said waxes and about 15% maximum of said other hydro¬ phobic material .

8. The mild personal cleansing bar of Claim 7 wherein said level of wax is from about 5% to about 20%; and/or wherein said bar contains a non-soil-load diluent synthetic surfactant at a level of from 5% to 40%; and preferably wherein said non-soil-load diluent synthetic surfactant contains at least 90% saturated Ci6 to Ci8 alkyl chains; and preferably wherein said diluent synthetic surfactant level is from 10% to 35%.

9. A mild personal cleansing bar comprising: from about 20% to about 50% lathering mild synthetic surfactant and from about 5% to about 50% of magnesium soap; wherein the ratio of said lathering mild synthetic surfactant to said soap is from about 10:1 to about 0.4:1; from about 1% to about 10% electrolyte; and from about 2% to about 15% water; said bar having a pH of from about 6.5 to about 8.5 in a 1% aqueous solution at 25'C; and wherein said lathering mild surfactant is selected from C12-C14 alkyl glyceryl ether sulfonate and C12-C14 sarcosinate and mixtures thereof; and preferably wherein said sarcosinate is present at a level of from about 2% to about 25% on a bar weight basis and said pH is from about 7 to about 8.

10. The mild personal cleansing bar of Claim 9 wherein said bar contains from 1% to about 40% of hydrophobic material selected from the group consisting of waxes; and other hydrophobic material including free fatty acids containing from about 8 to about 18 carbon atoms; mono-, di-, and triglycerides; fatty alcohols con¬ taining from about 8 to about 18 carbon atoms; and mixtures thereof; wherein said composition contains about 25% maximum of said waxes and about 15% maximum of said other hydrophobic material; and wherein said sarcosinate is present at a level of from about 3% to about 20%; and preferably wherein said level of wax is from about 5% to about 20%; and preferably wherein said bar contains a non-soil-load diluent synthetic surfactant at a level of from 5% to 40%; more preferably wherein said non-soil-load diluent synthetic surfactant contains at least 90% saturated Ciδ to Ci8 alkyl chains and said diluent synthetic surfactant level is from 15% to 20%.

11. The mild personal cleansing bar of Claim 9 wherein said lathering mild surfactant level is from about 25% to about 45% and said non-soil-load synthetic surfactant is from about 15% to about 20%; and said magnesium soap is from about 10% to about 40%.