Description:
The present invention relates to a translucent and/or substantially transparent non-irritating relatively low-hygroscopic moisturizing cleansing bar and to methods of preparing the same.
Translucent or substantially transparent soap bars have been available for consumer use for some time now. These soap bars are generally glycerine-based or alcohol-based to obtain the desired clarity and contain high levels of sodium and/or potassium stearate, namely 65 percent or more and when dissolved in water exhibit alkaline pH's of 8.5 or more and usually at least 9.5. These soaps have been said to be substantially less irritating than conventional non-translucent or non-transparent soap bars which contain from 65 to 95 percent sodium stearate and exhibit alkaline pH's ranging from 9.8 to 10.1. However, even the glycerine-based soap bars of pH's in the area of 9.5 or more have been found to be irritating to the skin and highly undesirable for use by those having particularly sensitive skin.
It has also been found that glycerine-based soap bars exhibit relatively high hygroscopic tendencies, that is they absorb water on the surface thereof, which causes the bar's surface to slough and become scaly.
With respect to the alcohol-based soap bars, it has been found that alcohol evaporates therefrom over relatively short periods of time, thereby causing a reduction in size and clarity of the bar. The loss of alcohol also causes the soap bar to become rubbery.
Most conventional soap bars may include up to about 2- 4 percent fragrances usually in the form of perfume oils. Unfortunately, the amount of fragrances employed in such bars is limited to 4 percent or less inasmuch as larger amounts impart an undesirable soft consistency and unpleasant color to the bar. Even with the presence of perfume oils, these soap bars leave only negligible traces of perfume fragrances on the skin after the soap is rinsed therefrom, which usually disappears after relatively short periods. The loss of perfume fragrances or smell from the skin can be attributed to the high concentration of fatty acid soaps present in and the relatively high pH's of prior art soap bars.
In accordance with the present invention, there is provided a translucent and/or substantially transparent non-irritating relatively low-hygroscopic conditioning cleansing bar of relatively low sodium stearate concentration and only slightly alkaline pH. The cleansing bar of the invention is thus substantially less irritating than prior art soap bars, transparent or otherwise, and retains fragrances in the bar and on the skin after application and rinsing, for substantially longer periods than prior art soap bars. In this respect, the cleansing bar of the invention has been found to produce effects similar to those produced by the use of bath oils in baths. Further, the cleansing bar may be employed as a shampoo bar, particularly suitable for children, inasmuch as it is substantially non-irritating to the eyes. The present bar does not produce the usual stinging effects or tearing normally associated with conventional soap bars used as shampoos. The cleansing bar of the invention is particularly advantageous in that it is highly water-soluble. Thus, it gives good cleansing action, in a gentle manner, without harsh scrubbing. Furthermore, it can be easily rinsed from the skin or hair, without leaving an undesirable residue and leaves the skin feeling soft and refreshed.
The translucent and/or substantially transparent cleansing bar of the invention comprises up to about 20 percent by weight sodium stearate and preferably from about 15 to 20 percent by weight thereof, up to about 10 percent by weight polyethylene glycol having a molecular weight within the range of from about 200 to about 800 and preferably from about 7 to about 10 percent by weight thereof, up to about 6 percent by weight polyethylene glycol having a molecular weight within the range of from about 800 to about 4,000 and preferably from about 3 to about 6 percent by weight thereof, up to about 8 percent by weight propylene glycol and preferably from about 5 to about 8 percent by weight thereof, quaternized dihydroimidazole detergents in an amount within the range from about 10 to about 50 percent by weight and preferably from about 10 to about 35 percent, an alkanolamide in an amount within the range of from about 4 to about 10 percent by weight and preferably from about 6 to about 9 percent and water, preferably deionized water, in an amount within the range of from about 6 to about 20 percent by weight and preferably from about 8 to about 14 percent.
When dissolved in water the cleansing bar of the invention has a slightly alkaline pH ranging from about 8 to about 9.5 and preferably from about 8.5 to about 9.0. The pH of the cleansing bar may be maintained at the above levels by employing conventional mild organic acid buffers such as citric acid, tartaric acid, stearic acid or lactic acid.
In effect, the cleansing bar of the invention is a chemically balanced formula containing no free acids and no free alkali which can produce skin irritation. Even when dissolved in water, the cleansing bar will not irritate or feel harsh to the skin and will not upset the acid-alkaline balance of the skin.
In addition, the cleansing bar of the invention may contain up to 20 percent emollient oils without losing hardness or clarity. In fact, in any of the after-disclosed formulations the cleansing bar of the invention exhibits sparkling clarity and retains its hardness, is easily rinsed from the skin or hair, and is substantially less softening, when in non-use and stored in conventional soap dishes than prior art clear or transparent soap bars. Furthermore, the cleansing bar of the invention does not produce drying of the skin as do prior art soap bars which depend upon alcohol (ethyl alcohol) for clarity. Accordingly, the cleansing bar of the invention is particularly suitable for use on sensitive skin such as for use on a baby's skin or as a shampoo, particularly for babies.
Where the cleansing bar of the invention is employed as a fragrance or perfume bar, it can include perfume oil(s) in amounts within the range of from about 0.5 to about 10 percent by weight and preferably from about 1 to about 6 percent.
In addition, the cleansing bar of the invention may optionally include coloring agents, humectants, foamers, sunscreening agents, medications, preservatives, proteins, vitamins, polypeptides, alcohol, glycerine as well as an oily material such as mineral oil or lanolin and other conventional additives for soap bars including oily materials such as isopropyl myristate, castor oil, oleyl alcohol, polyethylene glycol stearates having a molecular weight above 1000.
As in the case of conventional soaps the sodium stearate although present in reduced concentrations acts as a gelling agent and provides a necessary detergent or cleansing function.
The relatively low molecular polyethylene glycols and propylene glycol are present to solubilize the sodium stearate and provide good after-feel of soaped and rinsed skin. The relatively high molecular weight polyethylene glycols are present to enhance the hardness of the cleansing bar and act as a co-solvent and coupling agent to achieve transparency.
The fatty acid alkanolamide is present to enhance the hardness and clarity of the cleansing bar and acts as a foam stabilizer as well. Examples of suitable fatty acid alkanolamides include myristic diethanolamide, lauryl-myristyl diethanolamide, luric diethanolamides or coconut-diethanolamide. The preferred fatty acid alkanolamide is myristic diethanolamide.
The type detergents to be used in this invention which are termed quarternized dihydroimidazoles are intended to be those encompassed by the following formula: ##EQU1## wherein R is a straight or branched chain alkyl or alkylene group of from 3 to 25 carbon atoms, preferably 9 to 13; R 2 and R 3 are hydrogen or a straight or branched chain lower alkyl group of from 1 to 6 carbon atoms; Z is hydrogen or R 4 SO 3 wherein R 4 is a straight or branched chain alkyl or alkylene group of from 2 to 24 carbon atoms, preferably 10 to 14; X is sodium, (CH 2 ) n2 COOH, or (CH 2 ) n2 COONa; Y is hydrogen or sodium and n, n 1 and n 2 are integers from one to four.
The preferred detergents are those of the following formula and are available from the Miranol Chemical Co., Inc., Irvington, N.J. under the subtitled trade names. ##EQU2## Miranol C 2 M Cons. - Whole Coconut Dicarboxylate. ##EQU3## Miranol C 2 M-SF Conc. - Whole Coconut Dicarboxy Salt Free. ##EQU4## Miranol CM Conc. - Whole Coconut Monocarboxylate. ##EQU5## Miranol HM Conc. - Pure Lauric Monocarboxylate. ##EQU6## Miranol HM - Pure Lauric Dicarboxylate. ##EQU7## Miranol 2MCA Modified -Coconut & Lauric Carboxy/Sulfate.
It is also understood that a combination of detergents may be used in the present invention, such as Miranol C 2 M (15 percent) and Miranol HM (15 percent), in place of a single detergent such as Miranol C 2 M (30 percent). Thus the term detergent is intended to encompass one or a combination of detergents and the percentage ranges that follow are intended to encompass the total percent of the single detergent used or the total percent of the combination employed.
In preferred compositions of the invention, mineral oil will be present in an amount within the range of from about 1 to about 12 percent by weight so that the bar will have a soothing effect on the skin. Lanolin may also be included in concentrations ranging from about 1 to 8 percent alone or in conjunction with mineral oil, to impart good hair or skin substantivity to the cleansing bar.
Preferred cleansing bar formulations in accordance with the present invention are disclosed in the working examples set out hereinafter.
The cleansing bar of the invention can be prepared employing any of the following methods. In one method, all of the ingredients to be used in forming the cleansing bar, except perfume oil, are combined in a closed system, for example an Abbe Mill, and the ingredients heated up to 90°C and preferably at a temperature within a range from about 80° to about 90°C until a homogeneous and clear mixture in the form of a thick syrup is formed. Thereafter, perfume oil(s) is added with mixing. The mixture is then cooled down to about 70° to 75°C, poured into molds, and allowed to cool to below 70°C, for example to about 66°C until a gel forms which hardens into the cleansing bar of the invention.
In an alternate procedure, the high molecular weight polyethylene glycol and fatty acid alkanolamide are heated to a temperature within the range of from about 70°C to about 85°C and preferably at from about 75° to about 80°C to melt the same. Thereafter, the low molecular weight polyethylene glycol, propylene glycol, deionized water, detergent, and other ingredients which may be present such as lanolin and mineral oil, are added and the mixture heated in a closed system to a temperature up to about 90°C and preferably from about 85°C to about 90°C while mixing. The mixture is maintained at the latter temperature and sodium stearate is then added with mixing until it is dissolved. Mixing is continued until a uniform mixture is obtained. The uniform mixture is cooled down to a temperature ranging from 70° to 75°C. Thereafter perfume oil(s) is added with mixing until a homogeneous and clear mixture is obtained. The mixture is then poured into molds and allowed to cool to below 80°C to form a gel which hardens into the cleansing bar of the invention.
The following examples further illustrate the present invention but is not intended to be limited thereby.
EXAMPLE 1
All of the ingredients set out below with the exception of perfume oil are mixed in an Abbe Mill and heated to about 90°C for 2 to 3 hours until a homogeneous and clear mixture in the form of a thick syrup is formed. Thereafter, perfume oil is added with mixing until a homogeneous mixture is obtained. The mixture is then cooled down to 75°C, poured into molds, allowed to cool down to 70°C to form the cleansing bar having the composition set out below in Table I.
Table 1 ______________________________________ Ingredient % by weight ______________________________________ Sodium Stearate 18.0 Polyethylene Glycol 400 8.0 Propylene Glycol 6.0 Deionized Water 10.0 Polyethylene Glycol 4000 4.0 Myristic Diethanolamide 7.0 Miranol C 2 M Conc. (70% active) 18.0 Amido-ether Sulfate Complex 19.0 Lanolin 2.0 Mineral Oil 6.0 Perfume 2.0 100.0% ______________________________________
The so-formed cleansing bar of the above composition is transparent and in fact of sparkling clarity and is substantially non-irritating to the skin, retains its pleasant fragrance for substantial periods of time and exhibits the same effect when used for showering as obtained when using bath oil in a bath. The above composition when dissolved in water has a pH of about 8.0 - 8.5.
EXAMPLE 2
Polyethylene glycol having a molecular weight of 4,000 (4.0 g) and myristic alkanolamide (7.0 g) are mixed together and heated to 75°C to melt the same. Thereafter, polyethylene glycol having a molecular weight of 400 (7.5 g), propylene glycol (6.0 g), deionized water (10.5 g), Miranol C 2 M conc. 70 percent active (14.0 g), amidoether sulfate complex (15.0 g), lanolin (6.0 g) and mineral oil (10.0 g) are added and the mixture heated to 90°C in an Abbe Mill for minutes. Sodium stearate (16.0 g) is added to the mixture while maintaining the mixture at 90°C with mixing until it is dissolved and a uniform mixture is obtained. The mixture is cooled to 75°C and perfume oil (4.0 g) is added with mixing. The mixture is poured into molds and allowed to cool down to 70°C until the cleansing bar of the invention is formed. The composition of the cleansing bar so formed is set out in Table II below.
Table II ______________________________________ Ingredient % by weight ______________________________________ Sodium Stearate 16.0 Polyethylene Glycol 400 7.5 Propylene Glycol 6.0 Deionized Water 10.5 Polyethylene Glycol 4000 4.0 Myristic Diethanolamide 7.0 Miranol C 2 M Conc. (70% active) 14.0 Amido-ether Sulfate Complex 15.0 Perfume Oil 4.0 Alcohol Water-Soluble Lanolin 6.0 Mineral Oil 10.0 100.0% ______________________________________
The cleansing bar formed herein has essentially the same characteristics and properties of the cleansing bar formed in Example 1.
EXAMPLE 3
Employing the procedure of Example 1, except that perfume oil, lanolin and mineral oil are not present, a cleansing bar having the composition set out in Table III below is formed.
Table III ______________________________________ Ingredient % by weight ______________________________________ Sodium Stearate 19.0 Polyethylene Glycol 400 9.0 Propylene Glycol 7.0 Deionized Water 15.0 Polyethylene Glycol 4000 4.0 Myristic Diethanolamide 8.0 Miranol C 2 M Conc. (70% active) 18.0 Amido-ether Sulfate Complex 20.0 100.0% ______________________________________
The above cleansing bar has essentially the same properties and characteristics of the cleansing bar formed in Example 1.