Abradant Skin Cleanser

1. Field of the Invention

Acne is the sum total of the consequences of over activity and disorder activity of the oil producing or sebaceous glands of the skin. Adolescence is the time of life when sebaceous glands tend to be at peak activity. Aberrative conditions can also enhance sebaceous activity. As a result of a series of phases, beginning with the formation of a comedo, the comedo develops into a papule, which may then become a pustule, followed by a cyst, and finally the formation of scar tissue. Each of the phases is unsightly and can be embarrassing to a youth concerned with his or her appearance.

While the etiology of the various phases of the acne condition which was described above is not definitely known, it is known that the comedo is a plug which is the initial phase of the acne condition. The formation of the comedo is related to the oiliness of the skin. Therefore, varying efforts have been made to enhance the removal of the oil from the skin, so as to minimize the formation of the comedo.

Synthetic detergents have been employed, with or without, added keratoplastic and keratolytic agents. While these have been helpful in some cases, they have often been extremely drying and have failed to accomplish the desired desquamation. Topically applied abrasives and keratolytic materials have been used also for the treatment of acne. Frequently, while these agents have been found to be therapeutic, they have also been extremely irritating to the skin. Furthermore, the abrasives have tended to give a reddish meat-like coloration to the skin which is undesirable. Also, the small abrasive particles can become embedded in the follicles and skin, be difficult to remove, and act as plugs in the pores aiding in the pathogenesis of acne.

2. Description of the Prior Art

U.S. Pat. No. 3,092,111 describes an abrasive paste composition employing a hard abrasive. U.S. Pat. No. 2,494,827 discloses a detergent composition employing water insoluble crystalline metaphosphates which are made soluble by using combinations of cations. Other patents describing skin care lotions include U.S. Pat. Nos. 1,073,787, 1,452,093, 1,703,602, 2,581,278, and 3,062,721.

Novel hydrous abradant cream cleanser compositions are provided for treatment of oily skin and acne comprising relatively soft, fine mesh inorganic or sugar particles, which are substantially uniformly dispersed in a stable cream base and are sparingly soluble in water or have a reasonably slow rate of solution when formulated. In particular, sucrose, borates or other inorganic salts of comparable properties are dispersed as small particles in a sulfate or sulfonate surfactant cream base containing a small amount of water. The subject creams have long shelf life, provide a mild abrasive cleansing effect and rapidly dissolve upon rinsing or flushing of the skin.

Novel abradant cleansing creams are provided having substantial amounts of a relatively soft abradant particulate at least sparingly water soluble inorganic or organic salt or sugar in a surfactant cream base containing water. Small amounts of other materials may also be included to enhance the properties of the cream base. The significant ingredients in the composition are, therefore, the inorganic abradant salt or abradant sugar, the surfactant composition and water.

The compositions are found to be stable for long periods of time, as evidenced by accelerated tests.

The subject compositions do not liquefy on storage nor does the inorganic particulate material settle out. The composition retains its desirably creamy texture for long periods of time. In addition, the particulate matter retains its abradant activity, but responds to water flooding by dissolving at a reasonable rate. The composition has desirable foaming characteristics, despite the foam inhibiting effect of the particulate matter.

By reason of the excellent properties of the subject composition, when used, an abradant effect is obtained from the particles, while the surfactant aides in the removal of oil and dry skin released as a result of the action of the abradant. After the skin has been sufficiently abraded, by rinsing with increasing amounts of water, the particles rapidly dissolve leaving the skin fresh and clean, free of oil and dead skin.

The particulate matter employed should not disappear immediately when employed on the skin with water. Thus, the particulate matter as formulated, should have a moderately long lifetime on the skin in the presence of water. Preferably, the particulate matter will not dissolve in less than 15 sec with usage. Therefore, materials can be employed which have substantial water solubility, but when compounded in the formulations of this invention have a reasonably slow rate of solution when used.

With the salts, it is preferable that the salt be sparingly soluble in water, normally being soluble in an amount of less than about 30 weight percent at 40.degree. C and less than about 10 weight percent at 20.degree. C. The salt should be soluble in water at 20.degree. C in at least 0.5, usually at least 1 weight percent, and, preferably, at least about 3 weight percent. The salts must be nontoxic and nonirritating to the skin.

The particles will normally be of about 20-200.phi. mesh and usually at least 100.mu.. Mixtures of particles may be employed including particles of a size up to about 3,500.mu., more usually of up to about 3,000.mu.. Preferably, the average particle size will be in the range of about 125 to 750.mu..

The salts will generally have a hardness less than 6 and greater than 1 on the Mohs scale, usually from about 1.5 to 4. The hardness and size of the particles are both significant in the ability of the particles to remove or abrade dead skin from the skin surface. The size of the particles will also affect the rapidity at which the particles dissolve upon rinsing of the skin. Therefore, the more soluble the inorganic salt, generally, the more preferable the larger size particles. With the water soluble sugars, larger particles are also preferred.

The particles must be able to retain their character in the presence of water and surfactant, so that upon standing, the particles still retain their particulate character. Fluctuations in temperature on standing should not significantly modify the original size and nature of the particles so as to substantially change the physical character of the particles. Upon contact with gross amounts of water, the particles should dissolve at a moderate rate rather than substantially instantaneously. In this manner, a controlled abradant effect is achieved as one partially removes the cleanser and skin debris, while still retaining a substantial proportion of abradant particles.

The salts which are employed will be primarily alkali metal salts, particularly sodium and potassium, and more particularly sodium. The anion will normally be a complex anion, such as borate. Particular salts are sodium tetraborate decahydrate (borax) and potassium pentaborate octahydrate. The borax is particularly preferred, because of its excellent shelf life and retention of its original physical properties in combination with the other materials employed.

Other than the borates, citrates, monobasic phosphates and pyrophosphates of interest, particular salts of interest are sodium citrate, monobasic sodium phosphate, and sodium pyrophosphate.

Of the sugars, the sugar of particular interest is sucrose.

The next material employed is the surfactant, which may be a single surfactant or a mixture of surfactants. As the major component of the surfactant, a sodium salt of a derivative of sulfuric acid is preferred, particularly sulfonates and sulfates, more particularly alkyl sulfonates.

The preferred sulfates and sulfonates come under the classification, "Foaming Agents." Chester, International Review of the Cosmetic, Perfumery, Detergent and Allied Industries, 46, 205 (1973); the article is entitled, The Function of Cosmetic Components. The sulfates and sulfonates are anionic foaming agents.

In combination with the anionic foaming agents may be employed nonionic surfactants, e.g. polyalkyleneoxy compounds, either etherified or esterified, where the alkylene group is of from 2 to 3 carbon atoms.

The sulfate and sulfonate foaming agents which are employed are for the most part conventional sulfates and sulfonates which are used to prepare creams. The foaming agents have the desired viscosity and feel properties associated with creams and are normally recommended by their suppliers for this purpose. They are frequently supplied as aqueous concentrates and upon the addition of the particulate matter to form the compositions of this invention, there is a significant enhancement of the viscosity of the medium. Therefore, the surfactant employed should have an initial viscosity which is sufficiently low, so that upon the addition of the particulate matter, the desired texture is achieved or, alternatively, other additives may be included which serve to modify the viscosity or flow properties of the cream.

The sulfate ester salts will normally be sodium salts of the monoesters of sulfuric acid having one or more alkyleneoxy groups, usually not more than about 4, more usually not more than about 3, having the other hydroxy group etherified or esterified with a fatty acid of at least about 10 carbon atoms, usually at least 12 carbon atoms and normally not more than 18 carbon atoms. The preferred sulfate esters are those having polyethyleneoxy groups having from 2 to 3 units, with the hydroxyl group etherified with a fatty alkyl of from 12 to 18 carbon atoms, more usually of from 12 to 16 carbon atoms.

The sulfonates are usually alkyl sulfonates, particularly taurates, where the amino group is disubstituted, one of the substituents being a fatty acid group of from 12 to 18 carbon atoms, more usually of from 14 to 18 carbon atoms and the other substituent being a lower alkyl group of from 1 to 3 carbon atoms, and usually methyl. The taurine derivatives are particularly preferred because of their creamy texture and the excellent properties of the combination of particulate matter, particularly borax, and the taurine derivative.

In addition to the sulfuric acid derivative detergent or surfactant, numerous other surfactants or emulsifiers may also be included in minor amounts. Of the nonionic surfactants or emulsifiers, these will normally be polyols, such as polyethyleneoxy, polypropyleneoxy, or combinations thereof, which may be further etherified or esterified and serve to affect the viscosity, feel, stability, etc. of the cream. Particularly, fatty acid esters of polyols, e.g. glycerol monopalmitate and polyethyleneoxy oleate, find use. The polyols will usually have 2 to 3 alcoholic groups. The nonionic surfactants will usually have HLB values in excess of 7 and generally less than 18. The nonionic surfactants not only aid surfactantcy, but enhance both physical and subjective characteristics of the cream to enhance its popular acceptability. The high molecular weight polyalkyleneoxy compounds also provide thickening. These compounds will normally have molecular weights in the range of 600 to 12,000.

In addition to nonionics, anionic surfactants may also be employed for modifying the viscosity, enhancing surfactantcy, or enhancing foaming. Illustrative of this type of compound is the sodium salt of laurylsulfoacetate.

Finally, neutral amides may also be used such as hydroxyalkylated fatty acid amides, e.g. n-hydroxypropyl or di(hydroxyethyl)lauramide or myristamide. These compounds serve as foam stabilizers (nonionic). Chester, supra.

In addition to the above components, there will normally be a number of additional additives to fulfill specific purposes. These additives include bacteriostats or bacteriocides, therapeutic agents, e.g. anti-dandruff, colorants, perfumes, fatty materials, particularly fatty acids and fatty alcohols of from 8 to 18 carbon atoms to enhance feel, e.g. cetyl alcohol, and the like.

Of the total composition, the particulate matter will vary from about 20 to 80 weight percent, preferably from about 25 to 60 weight percent and more preferred from about 35 to 60 weight percent.

The sulfuric acid derived surfactants or foaming agents will generally comprise at least 10, usually at least 15, generally not more than about 50 weight percent of the total composition. Of the cream composition (excluding the particulate matter) the surfactant will generally be in the range of about 15 to 70 weight percent, more usually in the range of about 20 to 60 weight percent.

When the sulfonate, e.g. taurate, is the major component of the surfactant, the sulfonate will normally be present in from 10 to 50, usually 10 to 30, weight percent of the cream composition. When the sulfate, e.g. fatty alkyl polyoxyalkylene sulfate ester salts, is the major component, the sulfate will normally be present in from about 20 to 70, usually 30 to 60, weight percent of the cream composition.

The water will be added in less than the amount which would dissolve the particulate matter in the composition. The water will be as initially added in at least 3 weight percent of the total composition, more usually at least 5 weight percent of the total composition and generally not exceed 50 weight percent of the total composition, more usually not exceeding about 40 weight percent of the total composition. Preferably, the amount of water will be in the range of about 10 to 30 weight percent. By initially added is intended that any dehydrating effect of the particulate matter or other materials is ignored and the amounts refer to that amount of water initially incorporated into the composition which is added as other than waters of hydration. Of the cream composition, the water will generally range from about 5 to about 65 weight percent, more usually from about 30 to 60 weight percent. While greater amounts of water may be added, particularly with materials at the lower range of water solubility, the higher amounts of water will usually reduce shelf life.

The nonionic materials will be added as required to achieve the desired viscosity, feel or other improved properties. The nonionic materials will normally be employed in relatively small amounts usually not exceeding 12 weight percent of the total composition, more usually not exceeding 10 weight percent of the total composition and generally being employed in at least about 2 weight percent of the total composition, when employed. In the cream, the nonionic materials will generally be present in from about 2 to 20 weight percent, more usually from about 3 to 12 weight percent.

The minor additives will be added in small but effective amounts, generally not totaling greater than 15 weight percent, more usually totaling not greater than about 12 percent of the cream composition. Individual additives will generally range from about 0.01 weight percent to 8 weight percent, more usually from about 0.05 weight percent to about 6 weight percent of the cream composition. Foam boosters and hair conditioners may range from 1 to 8 weight percent of the cream compositions.

The cream compositions can be readily prepared by mixing the various ingredients at an elevated temperature with agitation, followed by emulsification by mixing with a high speed shearing mixer. Normally, the ingredients are added incrementally in accordance with their solubility properties so that at each stage the materials are completely dissolved or homogeneously dispersed. When formation of the cream is completed, and the temperature reduced to below 40.degree. C, the particulate matter may be added with agitation so as to homogeneously disperse the particulate matter.

In order to demonstrate the subject invention, the following borate compositions were prepared and their properties tested under a variety of conditions.

Example 1 was prepared as follows: Arlacel-165, Standamul 0-20 and Irgasan DP-300 were heated to about 65.degree. C with agitation. Steol 4N, potassium sorbate, and Maypon UD were combined at 65.degree. C with agitation, followed by the addition of the color solution, when the potassium sorbate had dissolved. The two mixtures where then combined and agitated for three minutes, whereupon 10 percent of the Igepon TC42 was added with increasing agitator speed to provide emulsification. After allowing the mixture to cool to about 35.degree.-40.degree. C, the remainder of the Igepon TC42 was added gradually, followed by the addition of Lathanol LAL at a relatively low speed. The perfume was then added with low agitation followed by the addition of the borax with low agitation.

Examples 2 to 5 were prepared as follows. The Arlacel-165 and cetyl alcohol were combined and heated at about 60.degree. C, followed by the addition of Standapol ES 40 concentrate while maintaining the temperature with agitation. The heat was removed and the Standapol CS shampoo base added while agitating at a moderate speed until the mixture cooled to room temperature. The pH was then adjusted to 5.2 with 0.1 percent citric acid. Borax was added with mild agitation.

The remaining examples were prepared in accordance with the procedures previously described, except that Example 8 was adjusted to pH 6.4 with citric acid.

The compositions prepared were all found to be stable at room temperature for long periods of time, showed excellent abradant or scrubbing characteristics-- dissolved at a reasonable rate when flooded with water-- had good to excellent foaming characteristics and retained their creamy texture and desirable feel. Besides the long-term shelf life at ambient conditions, some of the compositions showed excellent stability under elevated temperature accelerated aging conditions. Those compositions which had relatively short lives under the severe elevated temperature test could be improved by the addition of small amounts of viscosity index improvers.

Physical stability tests were carried out as follows on Examples 6 to 9. The mixtures were heated for a period of time at 40.degree. C and any changes in the composition noted at the end of the time. The following indicates the results obtained.

Example 6 after 7 weeks, the texture had softened and the particles were unchanged;

Example 7, after three weeks, the base had liquefied indicating the desirability of a greater amount of thickener;

Example 8, after three weeks, the texture and particles were unchanged;

Example 9, after one month, the texture had softened on the surface and the particles were unchanged.

A study was carried out employing the formulation of Example 1. Borax particles by themselves of the same mesh (40-100) as the borax particles employed in the formulation were stirred for 90 sec with varying amounts of water at 45.degree. C and the percent by weight of the particles remaining after being stirred with water was determined. The formulation was stirred with water for only 60 sec. The amount of water varied from 2.5 to 12.5ml of water, and the weight of borax was 1.3g, while the weight of the formulation was 2g. While a somewhat greater weight percent of the particles in the formulation did not dissolve at the lower levels of water, above 5ml of water, the percent dissolved was substantially the same. Therefore, the borax present in the formulation would dissolve as the face is rinsed, since the solubility properties of the borax were not significantly modified by the presence of the various ingredients in the formulation.

In a second study, the borax and the formulation employed above were mixed with 15ml of water and the percent of the borax remaining at various times determined. It was found that the borax in the formula dissolved somewhat more rapidly than borax by itself, being gone in about 60 sec, while the borax by itself was substantially gone in 75 sec. Significantly, there was still a substantial amount of borax after 20 sec, in excess of ten percent of the original amount, so that as a person rinsed his face, the borax would not disappear instantaneously, but would continue to provide abradant action. Thus, one would obtain the surfactantcy and abradant action for a reasonable period of time to insure a thorough scrubbing of the face, without irritation or meaty appearance.

In addition to the studies with the borates, the following table indicates formulations prepared with other particulate matter and an evaluation of their abradant action and stability. These compositions were prepared in substantially the same manner as indicated for Example 1, except that the particular abradant particle was added in the place of borax. The basic formula set forth below reports the various materials as commercially available and not as to the active portion. Therefore, the specific amount of water is not identified. Reference to the prior table indicates the proportion of active material in each of the commercially available materials to permit calculation of the total amount of water added.

The following table shows the list of abradant particles tested in the basic formula for abradancy and short-term stability.

The subject compositions provide a therapeutic means for treating oily skin and acne. The compositions are stable for long periods of time, with the abradant material maintaining its abradant character. Good foaming characteristics are retained. The compositions can be smoothly and uniformly applied to the skin providing for mild abrasion of the skin, without irritation or significant reddening of the skin. In this manner, dead skin can be removed, as well as other debris, oil removed, and the pores cleansed of minor residues which may have become deposited in the skin.

Because of the solubility of the abradant cleanser, none of the particles will be captured and retained in any of the pores, nor need there be any concern in removing the abradant particles, which has proved annoying with nonsoluble abradant particles. Also, because the particles are slowly or sparingly soluble, the amount of abrasive action can be varied in accordance with the user. Thus, by controlling the amount of rinsing water, prolonged or short-term abradant treatment can be applied.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims.