US3179596A - Soap bar for dry skin - Google Patents

Description

United States Patent 3,179,596 SUAP BAR FOR DRY SKIN Richard Edward Farrar, Morris Plains, and Albert Lyle Schulernd, Nutiey, N.J., assignors to Colgate-Palmolive Company, New York, N.Y., a corporation of Delaware No Drawing. Filed May 20, 1960, Ser. No. 30,469 2 Claims. (Cl. 252-125) This invention relates to soap bars which are suitable for cleaning human skin. They are particularly useful as detergents for those persons who have skins deficient in oil content. When the skin possesses an unsatisfactorily low content of fats and oils or lipids it loses its suppleness, tends to become hard and unyielding and is prone to flaking and in more advanced cases cracking and peeling. From contacts with textiles and exposure to wind, sun and low humidity conditions, dry skins become irritated more readily than those which possess sufficient lipophilic content and extreme dryness disturbs the tactile senses enough often to cause discomfort and annoyance.

The problem of alleviating a dry skin condition is complicated by the everyday necessity for repeated contact of the skin with solutions and other media which tend to remove the desirable lipoids from the elithelial tissue. Thus, in cleansing of the skin the detergent which emulsifies the oily dirt thereon also removes desirable natural skin oils. To prevent or mitigate such removal, fatty substances have been added to soaps and detergents.

Usually the amount of fatty material which may be added to a soap bar is limited by the physical changes it effects in the bar, which changes often tend to make it softer and more difiicult to process at efficient production rates. Limited quantities of oleaginous material have little perceptible effect on the skin when they are only very minor proportions of the emulsifier (soap) present. Yet, in large scale speedy commercial production the use of greater proportions of lipophilic substances has been limited by the softening of the bar and the accompanying increase in processing difiiculties, which, under warm, humid ambient conditions, can be especially noticeable with automatic pressing machines incorporating multiple dies and a rotating diebox or spider. Excessively soft bars tend to be consumed too rapidly due to the ease of removal of softened soap from the bar by the normal rubbing action of the hands. Softer bars are also more easily marked by processing and packaging machines. Another significant disadvantage of highly superfattecl bars is in the observation by the consumer that bars containing amounts of oils which are suflicient to have a significantly beneficial effect on the skin often do not foam 0r lather as well as comparable detergents free of superfatting material.

According to the present invention a milled and plodded toilet soap bar comprises 70-80% sodium salt of higher fatty acids of 8 to 20 carbon atoms, of which acids 90- 75% thereof is of fatty acids of 16 to 20 carbon atoms and 1025% thereof is of saturated fatty acids of 8 to 14 carbon atoms, 4 to 7% of a mixture of hydrocarbons of about 16 to 32 carbon atoms and a glycerol content of 30 to 70% of the hydrocarbon weight. A bar of this description is particularly suitable for cleansing dry skin and simultaneously deposits oleaginous soap bar constituent on the skin. In a prefered formula in accordance with this invention a milled and plodded toilet soap bar comprises 78% settled white sodium soap derived from a mixture of about 20 parts coconut oil and 80 parts tallow, about petrolatum, 2.5% glycerol, 1.5% lanolin, 12% Water and 1% adjuvants. The soap employed is one from which substantially all inorganic salts, unreacted fats and oils and glycerol have been removed. The product has been found to deposit petrolatum on the skin in normal washing, leading to a higher lipophilic 'ice content thereof and improving the appearance and feel of the skin, as well as counteracting the tendency to drying of the skin after washing.

The water soluble soap, which is the major constituent of this product and contributes most to its desirable physical properties, such as cleaning power, satisfactory solubility, processability and appearance, as well as other use characteristics associated with good toilet soaps, is a mixture of sodium salts of higher fatty acids of 8 to 20 carbon atoms. The proportion of soaps containing 8 to 14 carbon atoms should be kept low in this bar, intended primarily for use in the cleansing of skin deficient in natural oils. Soaps of 8l4 carbon atoms are less unctuous in feel than the higher and unsaturated soaps and thereby give some users the impression that their application is drying to the skin. In the literature such soaps have been reported to be harsher to the skin than those of higher fatty acids but, when mixed with higher soaps, as in the present bars, no significant change in mildness was observed. Some lower saturated fatty acids of 8 to 14 carbon atoms should be present to give the soap a balanced mixture of detergents which is more amorphous, foams more quickly and better removes various types of dirt and soil from the skin. It has been found that at least 10% is desirable for these purposes and it is preferable that no more than 25% of the saturated soaps of 8 0t 14 carbon atoms should be present. The balance of the soap constituent is a mixture derived from fatty acids of 16 to 20 carbon atoms. Such a mixture will contain predominant proportions of stearic, oleic and palmitic acid soaps with minor proportions of palmitoleic and arachidic soaps sometimes present. These higher fatty acid soaps, give the bar a slip and oily feel to the skin when they are employed in the described proportions in a toilet soap of this composition and such a slip or lubricity is desirable in the present bars. At the 10-25% C -C 90 015-020 soap ranges a commercially acceptable and proven soap is obtained which can be manufactured easily and has the desirable combination of properties which suit it for use in a product primarily intended for cleansing dry skin.

The composition of this invention is primarily a soap bar with additional desirable characteristics resulting from the presence of the other recited constituents. To maintain the characteristics of a good toilet soap, even in the presence of the significant amounts of added material, it is important to kep the soap content high, not allowing the inclusion in the bar of large amounts of fillers or other soap substitutes. The amount of sodium soap present should be within the range of 7080% of the bar. When the soap content is decreased below 70%, the bar properties becomes materially modified, usually to its detriment for the particular use intended.

The sodium soaps in the present bars may be made by the usual soap making techniques which result in a product essentially free of inorganic salt, glycerol, unsaponified and unsaponifiable materials. It is preferred to use settled white kettle soap of good quality, which has been dried into the usual ribbon or chip form. The oil charge employed to obtain such a soap of higher fatty acid content specified is preferably composed of coconut oil and tallow. It is preferred to use parts tallow and 20 parts coconut oil but the proportions may be varied from 94:10 to 75:25.

Although the employment of a soap high in tallow con tent or other fats containing mostly saturated fatty acids of 16 to 20 carbon atoms gives a soap which is of good slip and not excessively drying to the skin, nevertheless, such a soap alone will not be especially pleasing or beneficial when used to wash skin surfaces low in lipid content. In the past, superfatting agents have been added to various detergent preparations. Among these were various petroleum hydrocarbons, including petrolatum. The present inventors have found that when significant proportions of petrolatum are employed, it has an effect discernible by persons afflicted with excessively dry skin conditions. Thus, if 4 to 7% of a mixture of hydrocarbons covering a range of about 16 to 32 carbon atoms per molecule and preferably averaging about 22 carbon atoms is included in a toilet soap composition, hands and face washed with such a preparation feel less taut and strained after use and the skin appears to be more supple and softer. It has been reported that flaking or scaling of the skin is prevented or decreased noticeably. Less than 4% of this hydrocarbon mixture or petrolatum is not sufiicient to give the desired significant effect and more than 7% will often change the physical characteristics of the bar to its detriment.

In the manufacture of toilet soaps and similar detergent preparations many factors govern the acceptability of the product. It is not enough to have a bar which is merely a good cleansing agent or even one which also improves the feel and appearance of the skin washed with it. Such a bar must also possess the physical characteristics which the consuming public has associated with high quality soaps. It must not be too soft, too soluble, subject to excessive gelation in the soap dish and it must form acceptable foam and lather. Also, the product must process readily and be capable of automatic high speed milling, plodding, pressing and wrapping. A bar containing only soap and the proportion of petrolatum recited is significantly different in some respects from a soap bar and, in general, the comparison of physical and processing properties, apart'from 'superfatting effect, is unfavorable to the petrolatum-containing detergent. The petrolatum or hydrocarbon oil mixture tends to soften the soap and make it more difficult to process. It also affects the performance and feel of a wetted bar, tending to slow down the development of good lathering and to reduce the desirable slipperiness of the bar.

It has been discovered that the addition to the soap and petrolatum bar of a sufficient quantity of glycerol, in accordance with this invention, has a benficial result on the product performance and helps it to be efficiently made in standard soap manufacturing equipment. The percentage of glycerol employed should be about half as much as that of petrolatum and preferably 2.5% glycerol is used. The glycerol content may be between 30 and 70% of the petrolatum weight. By employing these proportions of glycerol, a bar containing petrolatum can be obtained which possesses a greater hardness and toughness making the processability and product properties more closely resemble those of the usual soaps. It has been indicated by experimental comparisons that the glycerol also helps to increase the lathering power of these soaps containing petrolatum. Finally, the nature of the glycerol appears to be of some assistance in enabling the petrolatum to penetrate through the upper skin cell layers and helps it to be retained by the epithelial cells. Thus, tests made with radioactive petrolatum indicate that washing with the invented product results in a retention by the skin cells of a percentage of the petrolatum in the soap utilized. Data indicate that, even as far as 5 cell diameters below the surface of the skin, petrolatu-m has been absorbed which is retained despite rinsing. It is apparent that the presence of petrolatum under the skin surface will be contributory to improving the oil content of the epidermis and will consequently alleviate to some extent the feeling of dryness when skin oil content is subnormal.

One to 2.5% of lanolin, preferably 1.5%, has been found to be another desirable agent to be added to the present compositions. The lanolin, more closely approximating the chemical nature of the sebum, supplements the petrolatum and improves conditioning of the skin. Lanolin usually has a very detrimental effect on lathering power of soap, even more so than petrolatum, but

in the invented compositions this effect is lessened and the lather is improved by the presence of glycerine. A similar improvement is noted in the hardness and processing properties of bars containing both lanolin and petrolaturn, when glycerol is added.

Although both petrolatum and lanolin have a softening effect on the soap bar, as does the normal amount of moisture present in such bars, with the specified amount of glycerine it has been found possible to use rather high amounts of moisture in spite of the percentages of liquid and unctuous materials present. This decreases the necessity for drying soap chips to very low moisture contents. It also allows a saving in drying costs, permitting more rapid throughput of soap ribbons. At 10 to 16% bar moisture content, these compositions can be milled, plod- (led and pressed on standard factory equipment, this despite the presence of petrolatum and lanolin which would be expected, in these amounts, to make the formula softer, tackier and more difficult to manufacture efficiently.

Small percentages of adjuvants may be used to give the bar special desired properties and to improve its stability. The proportion of adjuvants is preferably kept low to maintain the essential soap-like characteristics of the bar. Among the adjuvants employed may be mentioned perfume, fluorescent dyes, stabilizers, antioxidants, solvents, pigmeuts and coloring agents. Sodium metabisulfite in the formula, even only at 0.1 to 0.2%, significantly improves the bar color on storage and is a preferred stabilizing and bleaching agent. Among the solvents, polyethylene glycol is preferably employed to dissolve bactericide, e.g., tetrachlorsalicylanilide, and better distribute it through the bar, when it is in the formula. Usually the content of additives will be less than 5 and preferably less than 2%.

The following example is given to illustrate the invention. It is not to be considered as limitative. All amounts and proportions are by weight, unless otherwise indicated.

Example Parts, percent Dried settled white kettle soap chips, essentially free of glycerine, unsaponified and unsaponifiable matter and inorganic salts and containing the moisture needed to result in the desired 12% bar moisture content, were blended in an amalgamator with a mixture of petrolatum, glycerine, and lanolin, after which an aqueous solution of sodium metabisulfite was added, blending continuing. Perfume and a minute amount of coloring were also added to the amalgamator and mixing was continued until the various constituents were substantially evenly distributed throughout the soap chips. The mix was also milled to a chip which varied in thickness from .005 to .012 inch, averaging about .008 inch, which was then plodded, cut, pressed into bar form and wrapped.

The above processing was carried out at a rate which was substantially the same as that at which ordinary toilet soap is produced. The bar processed well and did not stick to the mill roils, lose its desired chip form at the cut-off knife or deposit on the soap dies, which would result in spotting or pitting of the bars produced.

In a comparison of production of bars of this formula, with and without the glycerine content, it was found that the presence of glycerine increased mill and plodded power about 1020%, indicating an appreciable increase in firmness of the composition.

The product lathered well, tests indicating it to be of substantially the same activity in this respect as regular toilet soap, and also sulliciently hard and quick drying so that there was no problem of excessive consumption or gelation in the soap dish.

When radioactive (tritiated) petrolatum was employed in this formula, a thirty second wash followed by either one or two thirty second rinse periods, resulted in a finding that the skin cells, as far as 5 diameters below the surface, had deposited thereon measurable amounts of petrolaturn. In the upper layer of cells an average read ing of 9.9 l disintegrations/minute/milligram and at the fifth cell layer below the surface the activity was still 4.1 l0 whereas a regular bar gave a rating of only 50. (Tritiated petrolatum used was characterized by a disintegration rate of 1.6x 10 /minute/mil1igram.)

The formula given above was made with 6.0% petrolatum, instead of the combination of petrolatum and lanolin, other constituents remaining constant, except for a compensating increase in soap content. The bar made was made according to the same method, was tested and was found to be satisfactory but the lanolin-petrolatumglycerine combination is preferable. Subjects with dry skin conditions, who employed these bars, noted with approval the better feel of the skin and an increase in softness and suppleness, together with an improvement in appearance.

What is claimed is:

1. A milled and plodded toilet soap bar particularly suitable for cleansing dry skin and depositing oleaginous soap bar constituent on the skin, comprising 70-80% of soap substantially free of inorganic salts, unreacted fats and oils and glycerol, the soap being of higher fatty acids of 8 to 20 carbon atoms predominantly of 16 to 18 carbon atoms, 10-25% of the soap being of saturated fatty acids of 8 to 14 carbon atoms and 90-75% of 16 to 20 carbon atoms, being that derived from an oil charge of 10 to coconut oil and 90-75% tallow, 4 to 7% petrolatum, to of the petrolaturn of glycerol, 1 to 2.5% lanolin and 10 to 16% water.

2. A milled and plodded toilet soap bar particularly suitable for cleansing dry skin and depositing petrolatum on the skin comprising about 78% settled White sodium soap derived from a mixture of about 20 parts coconut oil and 80 parts tallow, which soap is substantially free of inorganic salts, unreacted fats and oils and glycerol, about 5% petrolatum, about 2.5% glycerol, about 1.5% lanolin and about 12% water.

Reierences Cited by the Examiner UNlTED STATES PATENTS 2,795,554 6/57 Shumard 252-407 2,894,986 7/59 Beaver et al. 252-107 XR 2,948,684 8/60 Thiele 252-407 FOREIGN PATENTS 444,165 4/36 Great Britain.

639,630 7/50 Great Britain.

760,210 10/56 Great Britain.

564,080 9/58 Canada.

JULIUS GREENWALD, Primary Examiner.

ALBERT T. MEYERS, Examiner.

Claims (1)

1. A MILLED AND PLODED TOILET SOAP BAR PARTICULARLY SUITABLE FOR CLEASING DRY SKIN AND DEPOSITING OLEAGINOUS SOAP BAR CONSTITUENT ON THE SKIN, COMPRISING 70-80% OF SOAP SUBSTNTIALLY FREE OF INORGANIC SALTS, UNREACTED FATS AND OILS AND GLYCEROL, THE SOAP BEING OF HIGHER FATTY ACIDS OF 8 TO 20 CARBON ATOMS AND PREDOMINANTLY OF 16 TO 18 CARBON ATOMS, 10-25% OF THE SOAP BEING OF SATURATED FATTY ACIDS OF 8 TO 14 CARBON ATOMS AND 90-75% OF 16 TO 20 CARBON ATOMS, BEING THAT DERIVED FROM AN OIL CHARGE OF 10 TO 25% CONCONUT OIL AND 90-75% TALLOW, 4 TO 7% PETROLATUM, 30 TO 70% OF THE PETROLATUM OF GLYCEROL, 1 T TO 2.5* LANOLIN AND 10 TO 16% WATER.