Cosmetic composition.

This invention relates generally to cosmetic compositions and, more specifically, to cosmetic compositions containing relatively large amounts of plant extracts.

Cosmetic products containing plant extracts have recently been energetically developed in order to supply consumers with natural cosmetics with high safety and in response to consumers' concern about achieving healthy skins with the aid of the natural cosmetic properties possessed by certain plant extracts.

However, since such natural active ingredients generally contain coloring or discoloring components, cosmetics with a high content of such components tend to undergo coloration or discoloration with time. Therefore, most of the commercially available cosmetics contain only a small amount of natural ingredients to avoid this coloration or discoloration problem.

By way of example, aloe plants have conspicuous effects in curing wounds, re-activating cells, and retaining heat. Therefore, remarkable cosmetic effects for roughened or chapped skins can be expected from cosmetics containing extract powder of aloe. However, in order to produce this therapeutic effect to a sufficient degree, it is necessary to use the powder extract in an amount so that the cosmetic has an aloe extract concentration similar to that of the original fresh plant. More specifically, it is necessary to mix at least 0.5 weight % of the extract powder into the cosmetic.

However, if aloe extract powder is mixed into, for example, cream of a white or pale blue color in a concentration of greater than 0.5%, the resulting cosmetic will gradually turn to yellowish brown with the lapse of time, presumably because of chemical changes of aloe ingredients such as organic acids, salts, saccharides and amino acids. In this circumstance, presently commercially available aloe-blended cosmetics have an aloe extract content of 0.1 weight % or less, and in consequence do not possess the best possible cosmetic properties.

The present invention has been made in the light of the foregoing problems.

In accordance with the present invention, there is provided a cosmetic composition in the form of an emulsion, comprising a cosmetically-acceptable emulsified medium and: <ul id="ul0001" list-style="none"><li>(a) 0.5 to 10 weight % of a plant extract as an active ingredient;</li><li>(b) 0.1 to 1.0 weight % of an ester having the general formula: <chemistry id="chem0001" num="0001"><img file="EP0218441A2_D0001.tif" /></chemistry>wherein R is an alkyl group having 1 to 5 carbon atoms;</li><li>(c) 0.05 to 1.0 weight % of sorbic acid or an alkali metal salt thereof; and</li><li>(d) 0.5 to 20 weight % of an alcohol having the general formula: <chemistry id="chem0002" num="0002"><img file="EP0218441A2_D0002.tif" /></chemistry>wherein R₂ is an alkyl group having 1 to 8 carbon atoms and n is an integer of 1 to 3.</li></ul>

The present invention will now be described in more detail below.

The plant extract used as an active cosmetic ingredient in the present invention is an extract from the leaves, roots, stalks or fruits of various plants such as Liliaceae plants, e.g. aloe; Cucurbitaseae plants, e.g. cucumber and snake gourd; compositae plants, e.g. pot marigold, chamomile, milfoil and arnica; and citrus plants, e.g. lemon. Extract of aloe is preferred for use herein. The plant extract may be either in the form of a liquid or a dried powder. The amount of the plant extract in the cosmetic composition is 0.5-10 weight %. When the extract is in a liquid form, the amount of the extract is calculated on the basis of its solid content.

According to the present invention, coloration or discoloration of the cosmetic composition is prevented by the inclusion of the above-defined components (b)-(d) in combination.

Component (b) is an ester of a lower alcohol with 1-5 carbon atoms with p-hydroxybenzoic acid. Illustrative of suitable esters are methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, isopropyl p-hydroxybenzoate, butyl p-hydroxybenzoate and isobutyl p-hydroxybenzoate. Mixtures of two or more of these esters may be used if desired. The amount of the ester component in the cosmetic composition should be 0.1-1.0 weight %, preferably 0.1-0.5 weight %. Whilst at least 0.1 weight % of , the ester is required to achieve a useful effect in preventing unwanted coloration of the cosmetic composition, on the other hand too high a content is disadvantageous because the emulsion can then become unstable.

Component (c) is sorbic acid or an alkali metal salt thereof. The alkali metal is preferably sodium or potassium. Component (c) is used in an amount of 0.05-1.0 weight %, preferably 0.05-0.2 weight %. An amount of component (c) below 0.05 weight % is generally insufficient to attain a useful coloration-preventing effect, but on the other hand an excess amount, above 1.0 weight % can cause the cosmetic composition to have an unpleasant odor.

Component (d) is an aliphatic alcohol having 1-8 carbon atoms. Monohydric, dihydric or trihydric alcohols may be used. Examples of suitable alcohols include methanol, ethanol, propanol, isopropanol, propylene glycol, dipropylene glycol, 1,3-butylene glycol and clycerin. At least 0.5 weight % of component (d) is generally required for attaining a useful coloration-preventing effect. An amount of component (d) above 20 weight % can adversely affect the stability of the emulsion, and the feel in use of the emulsified composition.

The components (a)-(d) are incorporated into a cosmetically-acceptable emulsified medium to form the cosmetic composition. The order of incorporation of the components (a)-(d) is not critical. Any emulsified medium conventionally used in emulsified cosmetics can be suitably used in the present invention. Both water-in-oil emulsion and oil-in-water emulsion may be used. The emulsified medium is generally composed of an oil of hydrophobic substance, water and an emulsifier.

Examples of oil or hydrophobic substance which can form an oil phase in the emulsion include waxes such as bees wax, whale wax and hydrous lanolin; hydrocarbons such as liquid paraffin, vaseline, ceresine, microcrystalline wax, squalene and- pristane; higher (long chained) fatty acids such as myristic acid, stearic acid and behenic acid; esters such as isopropyl myristate, isopropyl palmitate, myristyl myristate and octyldodecyl myristate; and mixtures thereof. The oil or hydrophobic substance is generally used in an amount of 1-70 weight %, preferably 5-60 weight %. In a case where the cosmetic composition is in the form of a cream, the amount of the oil or hydrophobic substance is preferably 20-60 weight %. In the case of a lotion, the substance is preferably used in an amount of 5-25 weight %.

Any customarily employed emulsifier may be used. Anionic, cationic and nonionic surfactants are suitably used. However, the use of nonioic surfactants is preferable for reasons of safety. The emulsifier is generally used in an amount of 0.5-10 weight %, preferably 1-3 weight %.

The cosmetic composition may further include various conventionally used additives such as an antioxidant, vitamins, an ultraviolet absorber, a moisturing agent, a chelating agent, perfumes, etc. Such additives are used in such an amount as not to adversely affect the objects of the present invention, generally in an amount of 0-1 weight %.

The cosmetic composition of the present invention may be in the form of a cream or lotion and may be used, for example, as massage cream, cold cream, nutrient cream, cleansing cream or emollient cream.

The following examples will further illustrate the present invention.

Example 1

An aqueous phase is maintained at 60°C, to which is added an oil phase, previously maintained at 70°C, with stirring by means of a homogenizer. The mixing is continued until a homogeneous emulsion is obtained. Then, a perfume is added and the emulsion is allowed to be cooled to ambient temperature with stirring by means of a paddle mixer, thereby to obtain cream. The above-mentioned aqueous phase is composed of aloe extract powder, sorbic acid, propylene glycol and water. The oil phase is composed of methyl p-hydroxybenzoate and the components shown in Table 1. The contents of respective ingredients of the cream are shown in Tables 1 and 2. The balance is water.

The aloe extract powder is a product obtained by pressing aloe plant, refining the resulting juice with activated carbon, and drying the refined extract under reduced pressure. One part by weight of aloe extract powder is obtained per 100 parts by weight of the original plant. <tables id="tabl0001" num="0001"><img file="EP0218441A2_D0003.tif" /></tables>

Example 2

Example 1 is repeated in the same manner as described to obtain cream having the composition shown in Tables 1 and 2. As seen from Table 2, the composition of the cream of Example 2 is the same as that of Example 1 except that propylene glycol is replaced by ethanol of an amount shown in Table 2.

Comparative Examples 1-5

Example 1 is repeated in the same manner as described to obtain five kinds of cream having the formulations shown in Tables 1 and 2.

Example 3

The various cream compositions obtained in Examples 1 and 2 and Comparative examples 1-5 are tested for stability during storage. Thus, each cream composition is filled in a 60 ml capped glass bottle and is allowed to stand at 40°C for 1 month. Then each cream is examined visually to check the color thereof. The results are shown in Table 2.

Example 4

Four kinds of cream compositions are prepared in the same manner as in Example 1 except that the aloe extract powder is replaced by Aloevera 200 (trademark of an aloe extract powder product of Ichimaru-Farcos Inc.), lemon extract powder, cucumber extract powder and chamomile extract powder. Stability tests are conducted in the same manner as in Example 3 to reveal that all of the cream compositions remain unchanged in color. <tables id="tabl0002" num="0002"><img file="EP0218441A2_D0004.tif" /></tables>