IL30741A - Oil-in-water skin care emulsion - Google Patents

Description

-nya IB'B1? o*oa Taw a*Vnn Oil-in-water skin care emulsion LUZIER IKCORFORATED 0:28978 This invention relates to stable skin care emulsions. More particularly, it relates to stable skin care oil-in-water emulsions containing water- soluble polypeptides.

· It has long been recognized that protein hydrolyzates have a beneficial effect on the skin, and as a consequence, they have been incorporated in skin creams and lotions. However, to be useful in cosmetics of this character, they have to be in a water-. soluble form and ordinarily appear in the aqueous phase of the composition.

It is also known that a number of other ingredients are advantageously included in skin care preparations which tend to improve the skin. These . are exemplified by such materials as mineral oil, lanolin or acetylated lanolin alcohol, refined wax, squalane (hexamethyltetracosane), etc. which tend to be hydrophobic in character. Since it is advantageous to add the benefits to the skin contributed by these materials . to the benefits of aqueous solution of protein hydrolyzates, attempts are made to incorporate them in the protein solutions. This is usually accomplished through the use of an emulsifier which forms an oil-in-water emulsion in which the hydrophobic materials constitute oil phase.

· Although, in theory compositions of the above type (i.e., oil-in-water emulsions containing the protein hydrolyzate in the water phase and the other hydrophobic skin conditioners, moisturizers, etc. in the oil phase) are very effective, as a matter of fact, there are severe limitations on these products because of their * tendency to be unstable. The principal difficulty is that these compositions have been very difficult to · preserve. This had resulted in the growth of organisms .in the composition which causes a coalescence of the emulsion.

Various attempts have been made to overcome this problem, all of which have left something to be . desired. Thus, for example, the use of a combination of methyl p- hydroxybenzoate, propyl p-hydroxybenzoate and benzalkanium chloride has been tried. However, these did not lead to a stable system which must also contain an anionic surfactant . Similarly, a combination of methyl . p-hydroxybenzoate, propyl p-hydroxybenzoate and 6-ethoxy- 2,4-dimethyl-in-dioxane has also been tried. This, however, was unacceptable in that it darkened the products.

Studies also tended to indicate that cosmetic formulations containing water-soluble polypeptides should . be preserved at the lowest possible acceptable pH. This placed a severe limitation on ingredients which could be incorporated in compositions of this character which would tend to raise the pH.

It has now been found that oil-in-water emulsions . containing protein hydrolyzates in the water phase and hydrophobic materials in the oil phase may be very effectively preserved and thus stabilized by using as a preservative a combination of methyl p-hydroxybenzoate, propyl p-hydroxybenzoate and sodium ethylmercurithio-salicylate. This system is effective in the presence of anionic surfactants (e.g., sodium lauryl sulfate).

Furthermore, it is effective in a pH range up to about 8.5 and causes no apparent darkening or oxidation of the product .

It is therefore an object of the present invention to provide a stable oil-in-water emulsion containing water-soluble polypeptides which is stable under the influence of temperature, time and normal storage conditions.

It is a further object of the present invention to provide a composition set out in the above object which will serve as a skin care composition capable of enhancing the absorption of water and polypeptide by the skin.

Yet another object of the present invention is to provide a composition of the character set out in the above objects which is capable of imparting to skin persistent velvet-smooth films.

Other and more detailed objects will be apparent from the following description and claims.

In preparing the skin-care, protein hydrolyzate (i.e., polypeptide) oil-in-water emulsion compositions of the present invention, it is necessary to use a water-soluble polypeptide. Since these materials are water-soluble, the resulting solutions have a viscosity which is substantially identical with water. Any of a variety of water-soluble polypeptides may be used for this purpose. These will usually have a M.V7. in the range of 1500 to 5000.

Of particular interest are those polypeptides which contain the amino acids ordinarily found in skin. The source of these materials are usually animal skins.

An especially useful polypeptide for the purpose of the present invention are hydrolysates obtained from tanned leather. These are generally characterized as polypeptides having an average molecular' eight of about 25ΟΟ.

The quantity of polypeptide that will be used in accordance with the present invention will vary, depending upon the particular type of composition that is desired. In general, however, it will constitute between .8 to 2 by weight of the total composition, and preferably about 1-5 by weight.

As noted above, the composition of the present invention is an oil-in-water emulsion. The polypeptide, because of its water solubility, and because it is readily transferable to the skin from aqueous solutions, is contained substantially in the aqueous phase.

In addition to the polypeptide described above, it 'is advantageous to include in this composition a number of materials which are beneficial in skin care.

Thus, for example, it is useful to incorporate therein squalane (i.e., hexamethyltetracosane) . This ingredient acts as a liquid vehicle compatible with skin and sebum. It speeds up percutaneous penetration, accelerates penetration through the horny layer. It is miscible with sebum and epidermal lipids, and stimulates skin respiration.

The quantity of squalane that may be used in accordance with the present invention may vary somewhat. ,-In general, it will constitute between about 2 to 3 by weight of the total composition, and preferably .5$· · This material is hydrophobic in nature. Accordingly, in the present emulsion it will constitute part of the oil phase of the emulsion.

Allantoin is another material which can advantageously constitute a component of the present . invention. It has been found to promote cell-proliferation and remove nectoric tissue. It protects the skin from drying out. and keeps it soft by helping to keep its proper moisture content . Allantoin is proven to be available to the tissues, whether in the form of creams, · lotions, or powders. Also it has been found to have a protein-dispersing (denaturant) effect.

The quantity of allantoin which may be incorporated in the present composition may also be varied depending on the results desired. Ordinarily, it will . constitute between .15$ to - 0$ by weight of the total composition,and preferably .20$. Furthermore, since the allantoin is hydrophilic in character, it will be contained in the aqueous phase of the composition.

In addition to the components mentioned above, · there may be contained in the compositions of this invention the usual additives for skin care preparations . This may include humectants, emollients, moisturizers, fillers, bulking agents, perfumes, emulsifiers, etc.

Furthermore, they may contain medicaments, and particularly medicaments which can help heal minor cuts or wounds.

. The following are illustrations of the various additives which can be incorporated in the present · invention: (a) Humectants - glycerine, propylene glycol, sorbitol polyethyleneglycol . (b) Emollients - lanolin and its derivatives, e.g., acetylated lanolins, ethoxylated . lanolin alcohols. Patty acid alcohols and esters . (c) Emulsifiers - glyceryl monostearate, polyoxyethylene glycol, sorbitan sesquioleate . (d) Healing Agents - ethyl aminobenzoate, urea.

· As noted above, an important aspect of the present invention is in the utilization of the combination of methyl p-hydroxybenzoate, propyl p-hydroxybenzoate, and sodium ethylmercurithiosalicylate as a preservative system. The quantity of the respective materials may vary somewhat. . However, the usual quantities that may be employed and the preferred quantities are set out in the table below. The percent by weight indicated below is on the basis of the total composition.

Range Preferred j> by Wt. $> by t. methyl-p-hydroxybenzoate .08 to .2 .1 propyl-p-hydroxybenzoate .03 to .1 .05 sodium ethylmercurithiosalicylate .01 to .03 .02 Ordinarily, the propyl-p-hydroxybenzoate will be contained in the oil phase of the present emulsion composition.

The methyl-p-hydroxybenzoate and the sodium ethylmercuri-thiosalicylate will comprise a portion or portions of the aqueous phase.

As noted above, the pH of the present composition can have a value up to about 8.5 · However, ordinarily, it will be in the range of about 6.5 to 8.5, and preferably in creams having a value of about 6.8 and in lotions having a value of about 8.2.

The following examples are further illustrative of the present invention. It should be understood, however, that the invention is not limited thereto.

EXAMPLE 1 A stable cosmetic cream is prepared as oil-in-water emulsion having the following composition, having a pH of 6.5-7Ό.

OIL PHASE COMPONENT PERCENT BY WEIGHT Viscosity 50-55 ) 10.0 Acetulan* 4.0 Stearic acid 4.0 Cetyl alcohol 2.0 Refined paraffin wax .0 Lanolin (odorless) 3.O Squalane 3.O Propyl p-hydroxybenzoate 0.05 Acetylated lanolin fraction. Pale yellow liquid d. 0.867; neutral reaction; acid No. Ο.36; saponification No. 190.3.

AQUEOUS PHASE COMPONENT PERCENT BY WEIGHT Glycerin 2.0 Borax 0.5 Triethanolamine 0.7 Polypeptide LSN (water soluble)* C aq. 4.0 Methyl p-hydroxybenzoate 0.1 Sodium ethylmercurithiosalicylate * 0.02 Allantoin 0.20 Distilled water q.s.lOO Components of the oil phase are melted together to l80°F. Components of the aqueous phase are dissolved by heating to l85°F. The oil phase is then added to the aqueous phase with mild mixing to room temperature.

EXAMPLE II A stable cosmetic lotion prepared from the following components having a pH of 8.0 - 8.5· OIL PHASE COMPONENT PERCENT BY WEIGHT Glyceryl monostearate 2.7 Cetyl alcohol 1.5 Acetulan 2.0 Squalane 3 · 0 Propyl p-hydroxybenzoate 0.05 Polypeptide, LSN: A water-soluble polypeptide having an average M.W. of about 2500 obtained from the partial hydrolysis of tanned leather.

AQUEOUS PHASE COMPONENT PERCENT BY WEIGHT Polypeptide LSN (water soluble) 0 aq. 2.0 Sodium lauryl sulfate (USP Powder) 0.3 Methyl p-hydroxybenzoate 0.1 Sodium ethylmercurithiosalicylate 0.02 Allantoin ' 0.2 Distilled water q.s. 100 The oil phase is added to the aqueous phase as explained in Example I. Allantoin is dissolved in ten parts by weight of water, then added after the emulsion is formed.

In this stable formulation, 0.3 percent by weight of sodium lauryl sulfate (anionic) was incorporated to find out whether the product can be stable in the presence of anionic detergent. Also, in this stable formulation, 2.0 percent by weight of Acetulan was incorporated in the cream to give the skin a velvet-smooth protective film. Also incorporated as a medicinal ingredient was 0.2 percent by weight of Allantoin. The emulsion was tested at 115°F^ temperature and freezing temperature for a period of 365 days. No rancidity, discoloration, or separation was observed.

Although the invention has been described with reference to specific forms thereof, it will be understood that many changes and modifications may be made without departing from the spirit of this invention.

Claims (7)

.'·' C L A I M S

1. Improved oil-in-water stable composition for skin care containing a water-soluble polypeptide e£-h«A e-aJL ' ~ , - 1 s 'UCt'u'g-and— oOTTb¾-lning' amino- -oxid-& ordinarily found in animal skins, in the aqueous phase, the improvement charac- terized by the fact that the composition contains a stabiliz- ing amount of a preservative system comprising methyl-p- hydroxybenzoate, propyl-p-hydroxybenzoate and sodium ethyl- mercurithiosalicylate substantially in the amounts, by weight of the total composition: (a) .08 to ,20% methyl-p-hydroxybenzoate, (b) .03 to .10$ propyl-p-hydroxybenzoate, and (c) .01 to .03$ sodium ethylmercurithiosalioylate.

2. An improved composition according to claim 1, the • ί improvement characterized by including from .15 to . 0$ by weight of allantoin and from 2% to 3$ by weight of squalane.

3· An improved composition according to olaim 2, the improvement characterized by the fact that the pH is in the range of from 6.5 to 8.5.

» A improved composition acoordlng to claims 1 to 3* the improvement characterized by including an anionic surfactant.

5· An improved composition according to'olaim the improvement characterized by including an emollient, a moisturizer and a humectant.

6* An improved composition according to claim 5» the improvement characterized by containing a material selected from the group consisting of lanolin and acetylated. lanolin 3070/ 2 alcohol.

7. An improved composition according to claim 6, the improvement characterized by the fact that the polypeptide has a molecular weight in the range of from about ISOO to 5000.