JP7735679B2 - Gel-type skin cleanser - Google Patents

Description

The present invention relates to a gel-type skin cleanser that is suitable for carrying around in a tube container.

Gel formulations are typically preferred for skin cleansing compositions such as facial cleansers and cleansers due to ease of use (e.g., preventing dripping between fingers when lathering or during massage) and aesthetic appeal (e.g., glossy appearance). To gel surfactant compositions, gelling agents and thickeners are used. Most commonly used gelling agents are carboxyvinyl polymers neutralized with a base (sodium hydroxide or triethanolamine). However, inorganic and organic salts can disrupt the gel, resulting in a low viscosity or liquid state depending on the type of surfactant used. On the other hand, limiting the amount of surfactant used can result in insufficient foaming and foam quality. Furthermore, the addition of these thickeners can cause problems, such as precipitation depending on the type and concentration of surfactants and other additives, storage conditions, and temperature during use, causing cloudiness in clear cleansers, changes in the foam quality of the surfactant itself, and a significantly worsened feel during use.

In response to these issues, Patent Document 1 investigates a gel-type skin cleanser composition with excellent usability and foaming power. However, without neutralizing the alkyl acrylate-alkyl methacrylate-polyoxyethylene copolymer, and using only the anionic surfactant described, usability, foaming, and foam quality are still insufficient.

As a cosmetic that solves this problem, Patent Document 2 proposes a gel-type skin cleanser that not only has excellent feel and usability, but also foams well and has excellent foam quality even when the total amount of surfactant is reduced, and is highly safe for the skin, by using a combination of a specific anionic surfactant and a specific copolymer and/or thickener.
However, when used, the product felt sticky and slimy due to the thickener.
In addition, since the detergent is usually applied by wetting the hands and then dispensed into wet hands, spreading is not an issue. However, when considering carrying the detergent in a tube container, it is necessary to spread the detergent with dry hands to prevent the container from getting wet when dispensed, and with existing technology it can sometimes be difficult to spread with dry hands.

Therefore, it has been difficult to achieve a gel-type skin cleanser that has a clear and beautiful appearance, excellent foaming and foam quality, is not sticky or slimy to the touch when used, does not drip from the tube container, and is easy to spread with dry hands.

Japanese Patent Application Laid-Open No. 2001-226255 JP 2013-112663 A

The object of the present invention is to provide a gel-type skin cleanser that has a transparent and beautiful appearance, excellent foaming and foam quality, is not sticky or slimy to the touch when used, does not drip from the tube container, and is easy to spread with dry hands.

The present inventors have discovered that the above problems can be solved by a gel-type skin cleanser containing the below-described components (a) to (d) in specific ratios, and have completed the present invention.
That is, the present invention is as follows.
(a) 3 to 15% by mass of a potassium salt of an unsaturated fatty acid having 18 carbon atoms;
(b) 3 to 15% by mass of a potassium salt of a saturated fatty acid having an even carbon number of 12 to 16,
(c) 0.001 to 0.5% by mass of a potassium salt of a saturated fatty acid having an odd carbon number of 13 to 17,
(d) 3 to 15% by mass of an amide amino acid type amphoteric surfactant represented by the following general formula (I),

(wherein R ¹ CO represents an acyl group having 8 to 20 carbon atoms, and M ¹ represents a hydrogen atom, an alkali metal, a ½ alkaline earth metal, ammonium, an organic ammonium, or a basic amino acid cation.)
The present invention relates to a gel-type skin cleanser containing the above-mentioned formula. Such a gel-type skin cleanser has a transparent and beautiful appearance, is excellent in foaming and foam quality, does not feel sticky or slimy when used, does not drip from the tube container, and is easy to spread with dry hands.

The gel-type skin cleanser of the present invention has a transparent and beautiful appearance, excellent foaming and foam quality, is not sticky or slimy to the touch when used, does not drip from the tube container, and is easy to spread even with dry hands.

Embodiments of the present invention are described below. The present invention is a gel-type skin cleanser containing the following components (a), (b), (c), and (d). Note that "gel-type" refers to a semi-solid state with fluidity. Each component is described below.

[Component (a)]
The component (a) used in the present invention is a potassium salt of an unsaturated fatty acid having 18 carbon atoms. The potassium salt of the unsaturated fatty acid incorporated into the gel-type skin cleanser of the present invention may be a potassium salt of the unsaturated fatty acid prepared in advance before incorporation, or may be a potassium salt of the unsaturated fatty acid formed by incorporating an equivalent amount of an alkaline agent into the unsaturated fatty acid in the gel-type skin cleanser system. Specific examples of unsaturated fatty acids include oleic acid. Gel-type skin cleansers generally contain free fatty acids (superfat). In the present invention, the unsaturated fatty acid may be added to the gel-type skin cleanser system after preparing the potassium salt of the unsaturated fatty acid, or the amount of alkaline agent added may be reduced when reacting the unsaturated fatty acid with the alkaline agent, leaving unreacted free fatty acid. In this case, the content of the alkaline agent, such as potassium hydroxide, is preferably 0.80 to 0.99 equivalents relative to the fatty acid.

In the present invention, the content of component (a) is 3 to 15% by mass, preferably 4 to 13% by mass, and even more preferably 5 to 11% by mass, based on the total amount of the gel skin cleanser. If the content of component (a) is less than 3% by mass, the ease of lathering, dripping from the tube container, and transparent appearance will be insufficient. If it exceeds 15% by mass, the foam quality will be poor, and the lack of stickiness and sliminess, as well as the ease of spreading with dry hands, will be insufficient.

[Component (b)]
Component (b) used in the present invention is a potassium salt of a saturated fatty acid having an even carbon number of 12 to 16 (also referred to herein as an "even-numbered saturated fatty acid"), in other words, a potassium salt of a saturated fatty acid having a carbon number of 12, 14, or 16. The potassium salt of a saturated fatty acid incorporated into the gel skin cleanser of the present invention may be a potassium salt of an even-numbered saturated fatty acid that has been prepared in advance before incorporation, or may be a potassium salt of an even-numbered saturated fatty acid that has been formed by incorporating an equivalent amount of an alkaline agent into the even-numbered saturated fatty acid in the gel skin cleanser system.
The potassium salt of an even-numbered saturated fatty acid may be a single substance or a mixture, and specific examples include a single saturated fatty acid potassium salt of one type of potassium laurate, potassium myristate, and potassium palmitate, or a mixed fatty acid potassium salt of two or more types, and it is more preferable that the potassium salt contains at least potassium laurate.

When component (b) contains potassium laurate, the content of potassium laurate is preferably 75% by mass or more based on the total amount of component (b). When the content of potassium laurate is within this range, a good balance between ease of lathering and transparent appearance can be achieved.
In terms of foam volume and foam quality, the potassium salt of an even-numbered saturated fatty acid is preferably a mixture of saturated fatty acid potassium salts. Gel-type skin cleansers generally contain free fatty acids (superfat). In the present invention, the even-numbered saturated fatty acid may be added to the gel-type skin cleanser system after preparing the potassium salt of the even-numbered saturated fatty acid, or the amount of alkaline agent added may be reduced when reacting the even-numbered saturated fatty acid with the alkaline agent, leaving unreacted free fatty acid. In this case, the content of the alkaline agent, such as potassium hydroxide, is preferably 0.80 to 0.99 equivalents relative to the fatty acid.

In the present invention, the content of component (b) is 3 to 15% by mass, preferably 4 to 13% by mass, and more preferably 5 to 11% by mass, based on the total amount of the gel skin cleanser. If the content of component (b) is less than 3% by mass, the ease of lathering, foam quality, dripping from the tube container, stickiness, and lack of sliminess will be insufficient. If it exceeds 15% by mass, the transparent appearance and ease of spreading with dry hands will be insufficient.

[(c) component]
Component (c) used in the present invention is a potassium salt of a saturated fatty acid having an odd carbon number of 13 to 17 (also referred to herein as an "odd-numbered saturated fatty acid"), in other words, a potassium salt of a saturated fatty acid having a carbon number of 13, 15, or 17. Examples of the potassium salt of a saturated fatty acid used in component (c) include potassium tridecanoate, potassium pentadecanoate, and potassium heptadecanoate, and it is preferable to include at least one of potassium pentadecanoate and potassium heptadecanoate, and it is more preferable to include both potassium pentadecanoate and potassium heptadecanoate.

When component (c) contains at least one of potassium pentadecanoate and potassium heptadecanoate, the combined content of potassium pentadecanoate and potassium heptadecanoate is preferably 95 to 100% by mass, and more preferably 97 to 100% by mass, of the total amount of component (c). When the combined content of potassium pentadecanoate and potassium heptadecanoate is within the above range, a good balance of ease of spreadability with dry hands and excellent foam quality can be achieved.

When potassium pentadecanoate and potassium heptadecanoate are used in combination, the mass ratio of potassium pentadecanoate/potassium heptadecanoate is preferably 1/30 to 30/1, more preferably 1/10 to 10/1, even more preferably 1/5 to 5/1, and particularly preferably 1/3 to 3/1. A mass ratio within the above range is more preferable in terms of ease of spreading with dry hands.
In the present invention, the content of component (c) is 0.001 to 0.5% by mass, preferably 0.002 to 0.3% by mass, and more preferably 0.005 to 0.1% by mass, based on the total amount of the gel skin cleanser. If the content of component (c) is less than 0.001% by mass, the ease of spreadability with dry hands and the foam quality may be insufficient, while if the content is too high, the effect commensurate with the amount blended may not be achieved, which may be economically disadvantageous.

[(d) component]
The component (d) used in the present invention is an amide amino acid type amphoteric surfactant represented by the following general formula (I).

(wherein R ¹ CO represents an acyl group having 8 to 20 carbon atoms, and M ¹ represents a hydrogen atom, an alkali metal, a ½ alkaline earth metal, ammonium, an organic ammonium, or a basic amino acid cation.)

In the formula, R ¹ CO is an acyl group, which is a residue of a linear or branched fatty acid having 8 to 20 carbon atoms. Specific examples of such fatty acid residues include saturated fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and isostearic acid, and unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid. Acyl groups derived from mixed fatty acids can also be used, and examples of such mixed fatty acids include coconut oil fatty acid and palm kernel oil fatty acid. Preferred acyl groups have 8 to 18 carbon atoms, more preferably 10 to 14 carbon atoms, and mixed fatty acids derived from coconut fatty acid are also preferred. An acyl group with fewer than 8 carbon atoms results in a poor feel on the skin after cleansing, while one with more than 20 carbon atoms results in poor foaming properties.

Furthermore, ^M1 in the formula represents an alkali metal, half alkaline earth metal, ammonium, organic ammonium, or basic amino acid cation, and examples thereof include potassium, sodium, half magnesium, half calcium, ammonium, triethanolammonium, a cationic residue of lysine, and a cationic residue of arginine, with potassium and sodium being preferred. Specific examples of component d include N-cocoyl-N'-hydroxyethyl-N'-carboxymethylethylenediamine sodium ("Nissan Anon GLM-R-LV" manufactured by NOF Corporation). One or more types of component d can be used.

In the present invention, the content of component (d) is 3 to 15% by mass, preferably 4 to 13% by mass, and more preferably 5 to 11% by mass, based on the total amount of the gel skin cleanser. If the content of component (d) is less than 3% by mass, the ease of lathering, dripping from the tube container, and transparent appearance will be insufficient. If it exceeds 15% by mass, the foam quality, lack of stickiness and sliminess, and ease of spreadability with dry hands will be insufficient.

Furthermore, from the viewpoint of improving transparency, the mass ratio of the total amount of components (a) and (d) to the amount of component (b) in the gel-type skin cleanser [total amount of components (a) and (d) / amount of component (b)] is preferably 0.5 or more, more preferably 1 or more, and even more preferably 1.5 or more.

[Other ingredients]
The gel-type skin cleanser of the present invention may contain other ingredients in addition to the above-mentioned components (a) to (d), provided that the effects of the present invention are not impaired. These other ingredients are those commonly used in cosmetics, and include, for example, lower alcohols such as ethanol, diols such as propylene glycol, sugar alcohols and sugar alcohol derivatives, thickeners such as carboxyvinyl polymers, sugars, surfactants, organic salts, inorganic salts, pH adjusters, chelating agents, antioxidants, disinfectants, blood flow promoters, anti-inflammatory agents, ultraviolet absorbers, ultraviolet scattering agents, vitamins, amino acids such as arginine, pigments, and fragrances, and may be incorporated within a range that does not impair the performance of the present invention.

〔water〕
In the gel-type skin cleanser of the present invention, the remainder other than the above-mentioned components (a) to (d) and other components blended as necessary is water. The water content is preferably 50 to 90% by mass, more preferably 60 to 80% by mass, based on the total amount of the gel-type skin cleanser.

[Production of gel-type skin cleanser]
The gel-type skin cleanser of the present invention can be produced by a known method. For example, the gel-type skin cleanser of the present invention can be produced by mixing a potassium salt of an unsaturated fatty acid having 18 carbon atoms as component (a), a potassium salt of a saturated fatty acid having an even number of carbon atoms (12 to 16) as component (b), a potassium salt of a saturated fatty acid having an odd number of carbon atoms (13 to 17) as component (c), an amide amino acid amphoteric surfactant represented by general formula (I) as component (d) and other components that may be added as needed, and water, heating the mixture to homogeneity, and then stirring and cooling the mixture to about room temperature.

The following examples and comparative examples further illustrate embodiments of the present invention, but the present invention is not limited to these.

[Examples 1 to 12, Comparative Examples 1 to 4]
The gel skin cleansers of Examples 1 to 12 and Comparative Examples 1 to 4, in which each ingredient was blended in the parts by mass shown in Tables 1 and 2, were evaluated using the following evaluation methods. The raw materials used were as follows. The raw material for the fatty acid potassium salt was obtained by adding 0.85 equivalents of potassium hydroxide to the following fatty acid. The ingredients common to Tables 1 and 2 were those shown in Table 3.
Oleic acid: Special reagent grade (Tokyo Chemical Industry Co., Ltd.)
Lauric acid: Special reagent grade (Tokyo Chemical Industry Co., Ltd.)
Myristic acid: Special reagent grade (Tokyo Chemical Industry Co., Ltd.)
Palmitic acid: Special reagent grade (Tokyo Chemical Industry Co., Ltd.)
Pentadecanoic acid: Special reagent grade (Tokyo Chemical Industry Co., Ltd.)
Heptadecanoic acid: Special reagent grade (Tokyo Chemical Industry Co., Ltd.)
N-cocoyl-N'-hydroxyethyl-N'-carboxymethylethylenediamine sodium: Nissan Anon (registered trademark) GLM-R-LV (active ingredient 27% by mass, the content shown in Table 1 is the amount converted to the active ingredient) (manufactured by NOF Corporation), a compound of general formula (I) in which R ¹ CO is an acyl group derived from coconut fatty acid and M ¹ is sodium; coconut oil fatty acid amidopropyl dimethylaminoacetic acid betaine, a compound not corresponding to general formula (I) (a comparative component for component (d))

<Evaluation method>
(1) Evaluation of lathering ease Twenty male and female panelists took 1 g of the gel skin cleanser in their hands, added cold water, and lathered it. The lathering ease was evaluated as follows, and the total score of the 20 panelists was calculated and evaluated.
2 points: If you feel it is very easy to lather.
1 point: If you feel it is somewhat easy to lather.
0 points: If it is difficult to lather.
The total scores of the 20 people were calculated and evaluated according to the following criteria and shown in the table.
⊚: The total score is 35 points or more and there are no panelists who gave a score of 0.
○: The total score was 30 or more but less than 35 points, and no panelists gave a score of 0.
△: The total score is 20 or more but less than 30 points, or the total score is 30 or more but there is a panelist who gave an evaluation of 0 points.
×: The total score is less than 20 points.

(2) Evaluation of Foam Quality Twenty male and female panelists took 1 g of the gel skin cleanser in their hands, added cold water and lathered it for 1 minute, and then evaluated the foam quality as follows. The total score of the 20 panelists was calculated and the evaluation was made.
2 points: When the foam feels fine and sufficiently elastic.
1 point: The bubbles are fine and feel slightly elastic.
0 points: The foam feels coarse and lacks elasticity.
The total scores of the 20 people were calculated and evaluated according to the following criteria and shown in the table.
⊚: The total score is 35 points or more and there are no panelists who gave a score of 0.
○: The total score was 30 or more but less than 35 points, and no panelists gave a score of 0.
△: The total score is 20 or more but less than 30 points, or the total score is 30 or more but there is a panelist who gave an evaluation of 0 points.
×: The total score is less than 20 points.

(3) Dripping from a Tube 30 g of a gel-type skin cleanser was filled into a 5 mm diameter tube, the lid was closed, and the tube was allowed to stand in a thermostatic bath at 25° C. After 30 minutes, the tube was removed from the thermostatic bath, and the lid was opened with the tube opening facing downwards. The state of the tube after standing for 1 minute was evaluated as follows:
◎: No dripping from the tube ○: Almost no dripping from the tube △: Slight dripping from the tube ×: Dripping from the tube

(4) Transparent Appearance The gel-type skin cleanser was filled into a screw tube and stored in a thermostatic chamber at 0°C or 5°C for one day, and the transparency was evaluated as follows.
◎: Not cloudy when stored at 0°C.
○: Cloudy when stored at 0°C, but not cloudy when stored at 5°C.
△: Cloudy when stored at 5°C, but becomes transparent when returned to 25°C.
×: Became cloudy when stored at 5°C and did not become transparent even when returned to 25°C.

(5) Non-stickiness and sliminess Twenty male and female panelists took 1 g of the gel skin cleanser in their hands, added cold water and lathered it for one minute, then rinsed it off with running water for 15 seconds. After that, they judged the stickiness and sliminess as follows, and the total score of the 20 panelists was calculated and judged.
2 points: Almost no stickiness or sliminess was felt.
1 point: Slight stickiness or sliminess is felt.
0 points: Sticky or slimy feeling.
The total scores of the 20 people were calculated and evaluated according to the following criteria and shown in the table.
⊚: The total score is 35 points or more and there are no panelists who gave a score of 0.
○: The total score was 30 or more but less than 35 points, and no panelists gave a score of 0.
△: The total score is 20 or more but less than 30 points, or the total score is 30 or more but there is a panelist who gave an evaluation of 0 points.
×: The total score is less than 20 points.

(6) Ease of spreading with wet hands Twenty male and female panelists took 1 g of the gel skin cleanser into their wet hands and judged the ease of spreading when spread as described below. The total value of the 20 panelists was calculated and the judgment was made.
2 points: If you feel it is very easy to stretch.
1 point: If you feel it is easy to stretch.
0 points: If you feel it is difficult to improve.
The total scores of the 20 people were calculated and evaluated according to the following criteria and shown in the table.
⊚: The total score is 35 points or more and there are no panelists who gave a score of 0.
○: The total score was 30 or more but less than 35 points, and no panelists gave a score of 0.
△: The total score is 20 or more but less than 30 points, or the total score is 30 or more but there is a panelist who gave an evaluation of 0 points.
×: The total score is less than 20 points.

(7) Ease of spreading with dry hands Twenty male and female panelists took 1 g of the gel skin cleanser into their dry hands and judged the ease of spreading when spread as follows. The total value of the 20 panelists was calculated and the judgment was made.
2 points: If you feel it is very easy to stretch.
1 point: If you feel it is easy to stretch.
0 points: If you feel it is difficult to improve.
The total scores of the 20 people were calculated and evaluated according to the following criteria and shown in the table.
⊚: The total score is 35 points or more and there are no panelists who gave a score of 0.
○: The total score was 30 or more but less than 35 points, and no panelists gave a score of 0.
△: The total score is 20 or more but less than 30 points, or the total score is 30 or more but there is a panelist who gave an evaluation of 0 points.
×: The total score is less than 20 points.

As shown in Table 1, each of the gel-type skin cleansers of Examples 1 to 12 was evaluated as having a transparent and beautiful appearance, excellent foaming and foam quality, no stickiness or sliminess when used, no dripping from the tube container, and excellent ease of spreading with dry hands.
In particular, the gel skin cleanser of Example 3, which contained 7% by mass of component (a), 10% by mass of component (b), and 0.01% by mass of component (c), received very good ratings in all evaluation categories.

On the other hand, as shown in Table 2, the gel skin cleansers of Comparative Examples 1 to 4 were not found to be sufficiently effective in any of the evaluation items, as shown below.
For example, the gel-type skin cleanser of Comparative Example 1, which did not contain a sufficient amount of component (a), was evaluated as being insufficient in terms of ease of lathering, dripping from the tube container, transparent appearance, and ease of spreading with dry hands.
The gel skin cleanser of Comparative Example 2, which did not contain component (c), was evaluated as being inferior in terms of foam quality and ease of spreading with dry hands.
The gel-type skin cleanser of Comparative Example 3, which contained an extremely small amount of component (d), was evaluated as being insufficient in terms of ease of lathering, dripping from the tube container, and transparent appearance.The gel-type skin cleanser of Comparative Example 4, which contained the comparative component (d), was evaluated as being insufficient in terms of dripping from the tube container.

Claims (1)

(a) 3 to 15% by mass of a potassium salt of an unsaturated fatty acid having 18 carbon atoms;
(b) 3 to 15% by mass of a potassium salt of a saturated fatty acid having an even carbon number of 12 to 16,
(c) 0.001 to 0.5% by mass of a potassium salt of a saturated fatty acid having an odd carbon number of 13 to 17,
(d) a compound represented by the following general formula (I):

(wherein R ¹ CO represents an acyl group having 8 to 20 carbon atoms, and M ¹ represents a hydrogen atom, an alkali metal, a ½ alkaline earth metal, ammonium, an organic ammonium, or a basic amino acid cation.)
3 to 15% by mass of an amide amino acid type amphoteric surfactant represented by the formula:
A gel-type skin cleanser containing