JP2011168553A - Skin detergent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weakly acidic skin detergent, foaming continuously, excellent in cleansing property and without having a tight skin feeling after finishing the cleansing. <P>SOLUTION: This weakly acidic skin detergent is provided by including an amphoteric surfactant as a main component, and further a fatty acid salt and a polyhydric alcohol. Since the weakly acidic skin detergent is excellent in cleansing property, and since the foaming by the amphoteric surfactant which is a main component, is maintained even on continuing the cleansing, the amount of amphoteric surfactant required for cleansing is less and also there is no flowing out of the detergent by the collapse of the foam. In addition, since its pH is weakly acidic which is close to that of the skin, the detergent has gentle-to-skin characteristics i.e. irritation to the skin is low and further it is excellent even in the comparison of the tight skin feelings after the cleansing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a weakly acidic skin cleanser, and more particularly to a weakly acidic skin cleanser that maintains foaming, is excellent in cleanability, and has no feeling of tension after being washed up.

Conventionally, fatty acid soaps (alkaline) have been widely used in skin cleansing agents because of their excellent foaming power and detergency, but these are also irritating to the skin and the feeling of tightness after washing. Have the problem. This is because human skin is inherently weakly acidic, so washing with these alkaline soaps will cause the pH of the skin to temporarily become alkaline, and it will take some time for the skin to return to weakly acidic after washing. This is because the load is large and excessive degreasing by washing.
In order to solve such problems, a skin cleansing agent (Patent Document 1) in which skin irritation is reduced by blending myristic acid, palmitic acid and stearic acid at a specific ratio, higher fatty acid salt with amide ether sulfate -Type anionic surfactant, alkanolamide-type surfactant and nonionic polymer are added to improve the foaming property and reduce skin irritation (Patent Document 2), cationic A liquid soap composition (Patent Document 3) has been proposed in which foaming and the like are improved by adding a polymer and polyethylene glycol, and the smoothness after washing is improved. However, even if the problem is solved, new problems such as stickiness and stickiness after rinsing will occur. , Do not be satisfied yet.
In addition, weak acidic detergents based on amino acid surfactants have been developed to eliminate the disadvantages based on the alkalinity of fatty acid soaps, but such detergents are foamed, compared to fatty acid soaps, It is inferior in terms of foam retention, etc., and remains slimy and difficult to wash away. Alkaline fatty acid soap has the property of being hardly soluble under acidic conditions, and it is technically difficult to incorporate the advantages of fatty acid soap in weakly acidic detergents at the same time, and has not been realized.
Further, when the amphoteric surfactant is a main component, there is a problem that although foaming is relatively good, the detergency is weak.

  In the first place, conventional cleaning agents are thought to exert a cleaning effect by forming micelles by surrounding the dirt such as foundation, lipstick, sebum floating from the skin with surfactant, but at this time, it is initially foamed. As the surfactant takes in these soils and forms micelles, it can no longer be in the form of bubbles. That is, the foam of the surfactant disappears as it takes in dirt such as foundation, lipstick, and sebum. For this reason, the more foam is taken in the dirt, the more the foam disappears, so in order to continue cleaning, it is necessary to additionally remove the foam and foam, resulting in the use of a large amount of surfactant. Become. Also, since the foam disappears and flows out as a result, it cannot be maintained in a standing position, especially when cleansing cosmetics, and there are restrictions in terms of use, such as impregnation with cotton. There was a problem.

JP-A-7-76514 Japanese Patent Laid-Open No. 10-158686 JP-A-2-142900

  An object of the present invention is to provide a weakly acidic skin cleanser that maintains foaming, has excellent cleanability, and does not have a feeling of tension after being washed up.

  As a result of diligent research, the present inventors have found that, if an amphoteric surfactant is the main component and a fatty acid salt and a polyhydric alcohol are blended under acidic conditions, bubbling will continue even if washing is continued, and cleaning properties are excellent. In addition, the present inventors have found that it is possible to provide a skin cleanser that does not have a feeling of tension after being washed up, and has completed the present invention.

That is, the present invention
(1) A weakly acidic skin cleanser comprising an amphoteric surfactant as a main component, and further comprising a fatty acid salt and a polyhydric alcohol,
(2) The weakly acidic skin cleanser according to (1) above, wherein the amount of the fatty acid salt is 0.05 to 3% by weight based on the total cleanser.
(3) The weakly acidic skin cleanser according to (1) above, wherein the amount of the fatty acid salt is 0.1 wt% to 0.5 wt% with respect to the entire cleanser.
(4) The weakly acidic skin cleanser according to any one of (1) to (3) above, wherein the amount of the amphoteric surfactant is 3 wt% to 30 wt% with respect to the total cleanser
(5) The weakly acidic skin cleanser according to any one of the above (1) to (3), wherein the amount of the amphoteric surfactant is 3 wt% to 10 wt% with respect to the total cleanser,
(6) The weakly acidic skin cleanser according to any one of (1) to (5) above, wherein the amount of polyhydric alcohol is 2 wt% to 15 wt% with respect to the entire cleanser,
(7) The weakly acidic skin cleanser according to any one of (1) to (5) above, wherein the amount of the polyhydric alcohol is 3% by weight to 8% by weight with respect to the entire cleanser.
(8) The weakly acidic skin cleansing agent according to any one of (1) to (7), wherein the fatty acid salt is a fatty acid alkali metal salt,
(9) Amphoteric surfactant is betaine type amphoteric surfactant, acyl glutamic acid type amphoteric surfactant, amine oxide type amphoteric surfactant, isethionic acid type amphoteric surfactant, methyl taurine type amphoteric surfactant and sarcosine acid The weakly acidic skin cleanser according to any one of (1) to (8) above, which is one or more selected from the group consisting of type amphoteric surfactants,
(10) The above (1) to (1), wherein the polyhydric alcohol is one or more selected from the group consisting of 1,3-butylene glycol, propylene glycol, dipropylene glycol, isopentyldiol, glycerin and xylitol. 9) the weakly acidic skin cleanser of any one of
(11) The weakly acidic skin cleanser according to any one of (1) to (10), wherein the pH is in the range of 5.0 to less than 7.0,
(12) The weakly acidic skin cleanser according to any one of (1) to (10) above, wherein the pH is in the range of 5.5 to 6.5.
(13) The weakly acidic skin cleanser according to any one of (1) to (12) above, which contains an organic acid,
(14) The weakly acidic skin cleanser according to (13) above, wherein the organic acid is citric acid or lactic acid,
(15) The weakly acidic skin cleansing agent according to any one of (1) to (14), which is used as a face wash,
(16) The weakly acidic skin cleansing material according to any one of (1) to (15), which is used by filling in a whisk.
(17) The weakly acidic skin cleanser according to (16) above, wherein the whisk is a pump former,
About.

The weakly acidic skin cleanser of the present invention has excellent detergency and, in addition, the foaming of the amphoteric surfactant that is the main component lasts even if washing is continued, so that the amount of surfactant required for washing can be reduced. In addition, since the cleaning material does not flow down due to bubble breakage, it has a feature that it can maintain a free posture such as a standing posture or a supine posture, particularly when cleansing cosmetics.
In addition, the weakly acidic skin cleansing agent of the present invention has a gentle nature on the skin that the pH is weakly acidic close to the skin, so the irritation to the skin is low, and it is also excellent in comparing the feeling of tension after washing. Have.

Fig. 1 is a drawing-substituting photograph showing the foundation and mascara on the back of the subject's hand. FIG. 2 is a drawing-substituting photograph showing a state where one push of foam (about 0.8 g) is taken on the back of the subject's hand painted with foundation and mascara.

  The amphoteric surfactant according to the present invention is not particularly limited as long as it can be used for a normal skin cleanser. For example, betaine type, acyl glutamic acid type, amine oxide type, isethionic acid type, Various types such as methyl taurine type and sarcosine acid type can be used.

  Examples of the betaine-type amphoteric surfactant include amidopropyl betaine type, aminoacetic acid betaine type, sulfobetaine type, imidazolinium betaine type, and alkylbetaine type. More specifically, for example, coconut oil fatty acid amidopropyl betaine (display component name “cocamidopropyl betaine”), lauric acid amidopropyl betaine (display component name “lauramidopropyl betaine”), palm kernel oil fatty acid amidopropyl betaine (Indicated component name “palm kernel oil fatty acid amidopropyl betaine”), amidopropyl betaine type such as palm oil fatty acid amidopropyl betaine, ricinoleic acid amidopropyl betaine; lauryl dimethylaminoacetic acid betaine, palm oil alkyldimethylaminoacetic acid betaine, Aminoacetic acid betaine type such as stearyldimethylaminoacetic acid betaine, stearyldihydroxyethyl betaine; N-alkyl-N, N-dimethylammonium-N-propylsulfonic acid salt, N-alkyl-N, N- Sulfobetaine type compounds such as methylammonium-N- (2-hydroxypropyl) sulfonate, N-fatty acid amidopropyl-N, N-dimethylammonium-N- (2-hydroxypropyl) sulfonate; Alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine (labeled component name “cocoamphoacetic acid Na”), N-lauroyl-N′-carboxymethyl-N′-hydroxyethylethylenediamine sodium (labeled component name “lauroamphoacetic acid” Na "), N-coconut oil fatty acid acyl-N'-carboxyethyl-N'-hydroxyethyl ethylenediamine sodium (labeled component name" cocoamphopropionate Na "), undecyl hydroxyethyl imidazolinium betaine sodium, undecyl-N - Examples include imidazolinium betaine type such as loxyethyl-N-carboxymethylimidazolinium betaine; alkyl betaine type such as coconut oil alkyl betaine (display component name “cocobetaine”), lauryl betaine, and the like. .

Examples of the acyl glutamic acid type amphoteric surfactant include sodium N-cocoyl glutamate and sodium N-lauroyl glutamate, and examples of the amine oxide type include palm oil alkyldimethylamine oxide (labeled component name “cocoamine oxide”. ]), Alkyldimethylamine oxide, lauramidopropylamine oxide, sodium cocoyl isethionate as an example of isethionic acid type, sodium cocoyl methyl taurate, sodium lauroylmethyl taurine, oleoyl as examples of methyl taurine type Examples of the methyl taurine sodium sarcosine acid type include sodium cocoyl sarcosine acid, cocoyl sarcosine acid triethanolamine salt, and sodium lauroyl sarcosine acid. Of these, betaine type and amine oxide type are preferable.
The betaine type is preferably an amidopropyl betaine type, an imidazolinium betaine type, or an alkyl betaine type, and more preferably an amidopropyl betaine type.

As the amide propyl betaine type, preferably coconut oil fatty acid amide propyl betaine (display name “cocamidopropyl betaine”), lauric acid amide propyl betaine (display component name “lauramidopropyl betaine”), palm kernel oil fatty acid amide propyl Betaine (labeling component name “palm kernel oil fatty acid amidopropyl betaine”) and the like, and as an imidazolinium betaine type, preferably 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium. Betaine (labeled component name “cocoamphoacetic acid Na”), N-lauroyl-N′-carboxymethyl-N′-hydroxyethylethylenediamine sodium (displayed component name “lauroamphoacetic acid Na”), N-coconut oil fatty acid acyl-N′- Carboxyethyl-N ′ -Hydroxyethylethylenediamine sodium (display component name “cocoamphopropionate Na”) and the like, preferably alkyl betaine type, palm oil alkyl betaine (display component name “coco betaine”) and the like.
Preferred examples of the amine oxide type include coconut oil alkyldimethylamine oxide (display component “cocoamine oxide”) and the like.

The amphoteric surfactant can be used by mixing one or more of the above-mentioned ones. Moreover, these amphoteric surfactants can be easily obtained commercially. Examples include Kawaken Fine Chemical Co., Ltd .: Softazoline (registered trademark) CH (display component name “cocoamphoacetate Na”), Toho Chemical Co., Ltd .: Obazoline (registered trademark) BC (display component name “cocobetaine”), Clariant Japan KK: Genagen CAB818J (display component name “cocamidopropyl betaine”).
The blending amount of the amphoteric surfactant according to the present invention is not particularly limited, but if it exceeds a predetermined amount, further improvement in detergency cannot be expected, which is economically disadvantageous and environmentally friendly. It is not preferable in consideration. On the other hand, if the amount is less than the predetermined amount, sufficient detergency cannot be exhibited. These predetermined amounts vary depending on the blending ratio of each component constituting the cleansing agent. Usually, the blending amount of the amphoteric surfactant is about 3% by weight to about 30% by weight with respect to the total amount of the skin cleansing agent. The range is preferably from about 3% to about 10% by weight, more preferably from about 5% to about 8% by weight.
In the skin cleanser of the present invention, the main component means a main component as a cleanser. Therefore, the skin cleanser of the present invention is one in which the amphoteric surfactant is blended as a main component of the cleanser, which means that no other surfactant is blended. Instead, as long as the effects of the present invention are not hindered, a relatively small amount to a small amount of other surfactant components may be contained.

  The fatty acid used in the fatty acid salt according to the present invention is not particularly limited as long as it can be usually blended in a skin cleanser, and specifically, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid , Fatty acids having 12 to 22 carbon atoms such as behenic acid, natural fats and oils (for example, olive oil, palm oil, palm oil, cottonseed oil, apricot kernel oil, avocado oil, olive oil, kukui nut oil, walnut oil, grape seed oil, corn oil Cocoa butter, coconut oil, sesame oil, wheat germ oil, rice bran oil, shea butter, sweet amordo oil, shortening, soybean oil, evening primrose oil, camellia oil, rapeseed oil, palm oil, palm kernel oil, peanut oil, castor oil, sunflower oil, Hazelnut oil, safflower oil, macadamia nut oil, mango butter, beeswax, cottonseed oil, etc. Properties oil or fish oil, horse oil, can be exemplified such as an animal fat) fatty acids derived from tallow and the like, can be used alone or in combination of two or more thereof. Among the fatty acids having 12 to 22 carbon atoms, preferred are fatty acids having 12 to 18 carbon atoms, more preferred are lauric acid, myristic acid, stearic acid and oleic acid, and even more preferred are lauric acid, An example is myristic acid. Among natural fats and oils, vegetable fats and oils are preferable, and coconut oil is particularly preferable. As fatty acids derived from such fats and oils, coconut oil fatty acids are particularly mentioned.

  Examples of the salt of the fatty acid salt include alkali metal salts and organic amine salts obtained by saponifying or neutralizing fatty acids with an alkali agent. Examples of the alkali agent used include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate; organic alkalis such as monoethanolamine, diethanolamine, triethanolamine, trimethylamine and triethylamine. As the salt of the fatty acid salt, an alkali metal salt is preferable, and as a preferable alkali agent, an inorganic alkali is exemplified, and potassium hydroxide, potassium carbonate, sodium hydroxide and the like are particularly preferable.

Among these fatty acid salts, preferred examples include fatty acid salts produced by a saponification salting out method or a cooking method using natural fats and inorganic alkalis, and more preferably, for example, potash soap base. . Potash soap base is a kind of fatty acid soap manufactured by a cooking method in which potassium hydroxide (caustic potash) is added to natural fats and oils, and it contains potassium laurate, potassium myristate, etc. as its main ingredients. It includes unreacted oils and oils derived from the above, glycerin produced by decomposition, and the like.
The fatty acid salt can be used by mixing one or two or more of the above.

Since the skin cleanser of the present invention is weakly acidic, the added fatty acid salt becomes a fatty acid in the cleanser and functions as an oil that assists in the cleaning power. Therefore, when a predetermined amount or more of the fatty acid salt is added, it is separated as an oily substance in the cleaning material, and the cleaning material is not uniform. Such a predetermined amount varies depending on the blending amount of each component of the cleaning material. The fatty acid salt usually functions as an anionic surfactant in an alkaline detergent, but in the present invention, the function is different as described above.
The blending amount of the fatty acid salt to the skin cleanser of the present invention is not limited as long as the effect of the skin cleanser of the present invention can be exhibited and the fatty acid generated under acidic conditions is not separated in the cleanser as an oily substance. . In other words, if the amount of the fatty acid salt is less than the predetermined amount, the cleaning power of the skin cleaning material is weakened. On the other hand, if the amount is higher than the predetermined amount, the fatty acid produced under acidic conditions is separated as an oily substance and a uniform cleaning material is obtained. Absent. These predetermined amounts vary depending on the blending ratio of each component constituting the cleaning material. Usually, the blending amount of the fatty acid salt is about 0.05% by weight to about 3% by weight, preferably It ranges from about 0.1% to about 2% by weight, more preferably from about 0.1% to about 0.5% by weight.
When the fatty acid salt is blended in the skin cleansing material of the present invention, it is usually blended after the fatty acid salt is previously prepared from the fatty acid and the alkaline agent, but the cleansing material is prepared by blending the fatty acid and the alkaline agent respectively. You can also.

As the polyhydric alcohol according to the present invention, any one can be used without particular limitation, but preferably a dihydric alcohol such as 1,3-butylene glycol, propylene glycol, dipropylene glycol, isopentyl diol, Examples thereof include trihydric alcohols such as glycerin and alcohols having higher valences such as xylitol. Of these, 1,3-butylene glycol, dipropylene glycol, and isopentyldiol are preferable.
The polyhydric alcohol can be used by mixing one or more of those described above.
The polyhydric alcohol is considered to function as a solvent for dissolving the fatty acid generated from the fatty acid salt in the cleaning material. Accordingly, when the amount is less than the predetermined amount, the fatty acid is separated as an oily substance and the cleaning material is not uniform. On the other hand, when the amount is larger than the predetermined amount, the sustainability of the amphoteric surfactant foam decreases. These predetermined amounts vary depending on the amount of each component in the cleaning material, but the amount of polyhydric alcohol in the skin cleaning material of the present invention is usually about 2% by weight based on the total amount of the cleaning material. To about 15% by weight, preferably about 3% to about 10% by weight, more preferably about 5% to about 9% by weight.

  The skin cleanser of the present invention is a cleanser whose pH is weakly acidic. In this case, weakly acidic means that the pH is generally in the range of less than about 5-7. A preferred pH range is from about 5.5 to about 6.5, more preferably from about 5.7 to about 6.3. In order to make the skin cleansing agent of the present invention weakly acidic, an organic acid can be blended as necessary. The blending amount of the organic acid is appropriately determined according to the composition of the cleaning material, and is adjusted to the target pH of the skin cleaning material of the present invention. Examples of the organic acid include citric acid, lactic acid, tartaric acid, ascorbic acid, phytic acid, malic acid, acetic acid, etidronic acid, and among these, citric acid and lactic acid are preferable. The organic acid can be used by mixing one or more of the above.

  In the skin cleanser of the present invention, within the range not impairing the effects of the present invention, in addition to the above-described components, components commonly used in skin cleanser, such as animal and plant derived fats and oils, silicones, lower alcohols, Extracts from animals and plants, moisturizers, fresheners, UV absorbers, anti-inflammatory agents, metal sequestering agents, vitamins, antioxidants, antiseptics / bactericides, pH adjusters, antioxidants, coloring agents, various fragrances, various solvents And the like can be appropriately blended according to the use and purpose thereof.

In the present invention, water is used in the balance so that the total amount of the cleaning material is 100% by weight. There is no limitation in the kind of such water, and generally purified water can be used.
The skin cleanser of the present invention is in a liquid form (liquid), preferably in the form of an aqueous solution, and can be produced by a conventional method. Furthermore, various dosage forms such as gel and cream can be obtained by conventional methods.
Examples of the use of the skin cleansing agent of the present invention include use as a facial cleanser, as well as other skin cleansing agents such as body soap, hand soap, body shampoo and the like. Among them, the skin cleanser of the present invention is preferably used as a facial cleanser because it is excellent in the persistence of foam and detergency, and also in the comparison of the feeling of pulling after washing.
The skin cleansing agent of the present invention can be used by filling in a whisk. Examples of such a whisk include a pump former, a sponge, a foaming net, a sponge (sponge), and a non-woven fabric.

The skin cleansing material of the present invention exhibits a long-lasting foam and excellent cleanability that are not found in conventional products, and also has little feeling of tension after being washed up. The mechanism is as follows (a) It can be considered as (e). That is,
(A) According to the skin cleanser of the present invention, the amphoteric surfactant as a main component plays a role as a medium for dispersing the dirt, rather than taking the dirt peeled off from the skin and forming micelles. Play more.
(B) In this case, the fatty acid generated from the fatty acid salt under mildly acidic conditions helps the soil to peel off from the skin and the soil removed from the skin to disperse in the amphoteric surfactant foam.
(C) Therefore, the amphoteric surfactant foam lasts forever.
(D) The amphoteric surfactant has an effect of preventing the reattachment of dirt by forming a film by the cation portion adhering to the skin.
(E) The fatty acid generated from the fatty acid salt under weakly acidic conditions becomes a salt of fatty acid potassium, fatty acid sodium or the like when the skin cleansing agent is washed away. For this reason, since it can be easily washed away, unlike an oil cleansing agent containing a conventional oil, there is no slimy feeling after use, and it is not necessary to wash twice.

In this specification, when there is a display of%, unless otherwise specified, it represents weight% (wt%).
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

  In the following Examples and Comparative Examples, each formulation (100% in total) is prepared by taking each component shown in a beaker so that the total amount becomes 200 g, and stirring it while heating to dissolve well. Until it was prepared.

Example 1
Amphoteric surfactant + fatty acid salt (pH: 5.8)
Cocamidopropyl betaine 7.2%
(Clariant Internatinal Ltd.,
Genagen CAB818J.
Same in comparative examples. )
1,3-butylene glycol (BG) 6.0%
Citric acid 0.08%
Potash soap base 0.33%
(Miyoshi Oil & Fat Co., Ltd.
Cosmetic soap KS100.
The same applies to other examples and comparative examples. )
Methylparaben 0.3%
Purified water balance

Example 2
Amphoteric surfactant + fatty acid salt (pH: 5.8)
Cocamidopropyl betaine 6.0%
(Evonik Industries,
Tego Betain L7. )
1,3-butylene glycol (BG) 3.0%
Potash soap base 0.33%
Methylparaben 0.3%
Purified water balance

Comparative Example 1
Amphoteric surfactant + fatty acid salt (PH: 9.5)
Cocamidopropyl betaine 7.2%
1,3-butylene glycol (BG) 6.0%
Arginine 0.05%
Potash soap base 0.33%
Methylparaben 0.3%
Purified water balance

Comparative Example 2
Amphoteric surfactant + nonionic surfactant (pH: 6.4)
Cocamidopropyl betaine 7.2%
1,3-butylene glycol (BG) 6.0%
Polyglyceryl oleate-10 0.3%
(Sunsoft Q-17S, manufactured by Taiyo Chemical Co., Ltd.
Same in other comparative examples. )
Methylparaben 0.3%
Purified water balance

Comparative Example 3
Amphoteric surfactant + fatty acid salt + nonionic surfactant (pH: 9.5)
Cocamidopropyl betaine 7.2%
1,3-butylene glycol (BG) 6.0%
Arginine 0.05%
Potash soap base 0.33%
Polyglyceryl oleate-10 0.3%
Methylparaben 0.3%
Purified water balance

Experimental example 1 (stability)
Each skin cleansing material of Example 1 and Comparative Examples 1 to 3 was placed in a refrigerator (4 ° C.) and allowed to stand sufficiently until each temperature reached 4 ° C. Thereafter, each skin cleanser was confirmed, but none of the properties changed.

Experimental Example 2 (Foam persistence / feeling of tension after washing)
Apply mascara (“Facio (registered trademark) Hyperstay Mascara Sports Deep Trick”, manufactured by Kose Co., Ltd.) with a width of about 5 mm and a length of about 25 mm on the back of the hand of five subjects who had previously washed their hands so as not to overlap the mascara. The foundation (“Lavanse (registered trademark) Liquid Foundation”, manufactured by Dovest Co., Ltd.) was spread on a round shape having a diameter of about 70 mm (FIG. 1), and the applied portion was dried with a dryer for 1 minute. Each skin cleansing material of Example 1 and Comparative Examples 1 to 3 is filled into a pump former, and 1 push foam (about 0.8 g) is taken on the back of each hand (FIG. 2) and wrapped with such foam. Gently washed and the foam persistence was evaluated according to the following criteria. At that time, the average value of five people was calculated and used for the duration of the foam.
A: Foam persisted for 3 minutes or more. O: Foam disappeared after 2 minutes and less than 3 minutes.
Δ: Bubbles disappeared in 2 minutes or more and less than 2 minutes and a half.
X: Bubbles disappeared in less than 2 minutes.
Next, when the foam disappeared, it was washed away with water, and the feeling of tension after washing was evaluated according to the following criteria.
◎: Everyone felt unsatisfactory ○: 3-4 people felt unsatisfactory △: 1-2 people felt unsatisfactory ×: 0 people felt unstressed

Experimental Example 3 (Detergency)
Apply the foundation and mascara on the back of the subject's hand (1 person) in the same manner as in Experimental Example 2, and then perform the same operation as in Experimental Example 2 to perform washing, and when the bubbles disappeared, rinse with water. . The detergency was evaluated according to the following criteria.
◎: Both foundation and mascara fell △: The foundation fell, but some mascara remained ×: Neither foundation nor mascara fell

(Experimental result)
The results of Experimental Example 2 and Experimental Example 3 are shown in the table below.

  From the above results, the skin cleanser of the present invention (Example 1) showed excellent characteristics in all of the persistence of foam, cleanability, and feeling of tension after washing. On the other hand, from Comparative Example 1 and Comparative Example 3, the excellent characteristics do not appear when the pH is alkaline. From Comparative Example 2 and Comparative Example 3, the fatty acid salt is replaced with a nonionic surfactant, or the fatty acid salt is further nonionic. It was also shown that the excellent properties did not appear when the surfactant was added.

  The skin cleanser of the present invention is useful as a skin cleanser, in particular, a facial cleanser, because it has excellent properties such as continuous foaming, excellent cleanability, and no feeling of tension after being washed up.

Claims (17)

  A weakly acidic skin cleanser comprising an amphoteric surfactant as a main component and further comprising a fatty acid salt and a polyhydric alcohol.   The weakly acidic skin cleanser according to claim 1, wherein the amount of the fatty acid salt is 0.05 to 3% by weight based on the total cleanser.   The weakly acidic skin cleanser according to claim 1, wherein the amount of the fatty acid salt is 0.1 to 0.5% by weight based on the total cleanser.   The weakly acidic skin cleanser according to any one of claims 1 to 3, wherein the amount of amphoteric surfactant is 3 to 30% by weight based on the total cleanser.   The weakly acidic skin cleanser according to any one of claims 1 to 3, wherein the amount of the amphoteric surfactant is 3 wt% to 10 wt% with respect to the total cleanser.   The weakly acidic skin cleanser according to any one of claims 1 to 5, wherein the amount of polyhydric alcohol is 2 to 15 wt% with respect to the total cleanser.   The weakly acidic skin cleanser according to any one of claims 1 to 5, wherein the amount of polyhydric alcohol is 3 to 8 wt% based on the total cleanser.   The weakly acidic skin cleanser according to any one of claims 1 to 7, wherein the fatty acid salt is a fatty acid alkali metal salt.   Amphoteric surfactants include betaine-type amphoteric surfactants, acylglutamic acid-type amphoteric surfactants, amine oxide-type amphoteric surfactants, isethionic acid-type amphoteric surfactants, methyltaurine-type amphoteric surfactants, and sarcosine acid-type amphoteric surfactants. The weakly acidic skin cleanser according to any one of claims 1 to 8, which is one or more selected from the group consisting of active agents.   The polyhydric alcohol is one or two or more selected from the group consisting of 1,3-butylene glycol, propylene glycol, dipropylene glycol, isopentyl diol, glycerin and xylitol. Weakly acidic skin cleanser.   The weakly acidic skin cleanser according to any one of claims 1 to 10, wherein the pH is in the range of 5.0 to less than 7.0.   The weakly acidic skin cleanser according to any one of claims 1 to 10, wherein the pH is in the range of 5.5 to 6.5.   The weakly acidic skin cleanser according to any one of claims 1 to 12, comprising an organic acid.   The weakly acidic skin cleanser according to claim 13, wherein the organic acid is citric acid or lactic acid.   The weakly acidic skin cleanser according to any one of claims 1 to 14, which is used as a face wash.   The weakly acidic skin cleanser according to any one of claims 1 to 15, which is used by filling in a whisk.   The mildly acidic skin cleanser of claim 16, wherein the whisk is a pump former.