Gel-type skin cleanser

Abstract

To provide a gel-like skin cleanser which hardly drips from a tube container, stretches easily even on the dry skin, is easily washed off when used without foaming, has excellent foaming on the skin when used with foaming and has good appearance transparency.SOLUTION: There is provided a gel-like skin cleanser which comprises (a) 7 to 25 mass% of a fatty acid potassium salt having 12 to 18 carbon atoms, (b) 4 to 15 mass% of an alkylhydroxysulfobetaine type amphoteric surfactant and (c) 0.001 to 0.5 mass% of a polymer containing 2-methacryloyloxyethyl phosphorylcholine and an alkyl methacrylate as constituent monomers, wherein the total of the component (a) and the component (b) is 15 to 35 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a transparent gel-type skin cleanser, and more specifically to a gel-type skin cleanser that is less likely to drip from a tube container, spreads easily even on dry skin, is easily rinsed off when used without lathering, and lathers well on the skin when used with lathering, and has a good transparency in appearance. [Background technology]

[0002] Skin cleansers come in a variety of formulations, but the most common are liquid cleansers that are foamed by adding water. In recent years, due to the growing awareness of time-saving and their convenience, foam-type cleansers that come out as foam have become more common. Foam-type cleansers do not require foaming, and the fine foam is expected to reduce friction on the skin during cleansing. However, because the foam loses elasticity while washing, it may not be effective enough in reducing friction on the skin, and there is a demand for cleansers with less friction.

[0003] Gel-type skin cleansers can meet this demand. Gel-type skin cleansers can sufficiently reduce friction between the hands and skin when used as a gel without lathering, but improvements are needed to address the following issues.

[0004] First, tube containers are often used for gel formulations, but if the product drips from the tube container, it can spill or make it difficult to control the amount you want to use, so it is important that the tube container does not drip. Furthermore, when gel cleansers are used in the bath, they are applied to wet skin, so spreadability is usually not an issue. However, with the increase in use outside the bath, such as in morning face washing, there is a demand for gel cleansers that are easy to spread even on dry skin. Furthermore, time-saving conscious users demand that the product not be sticky when rinsed off and be relatively easy to rinse off with running water.

[0005] On the other hand, in order to thicken a skin cleanser, a method using a gelling agent or a thickener is generally adopted. For example, Patent Document 1 discloses a gel-type skin cleanser containing a specific nonionic surfactant, a water-soluble polymer which is a polysaccharide or its derivative, and a polyhydric alcohol, each blended in a specific ratio. It is described that this cleanser can be used without lathering and has excellent massage effect during use, cleaning power, rinsing ability, etc. However, although this cleanser has better rinsing ability than conventional gel-type cleansers using water-soluble polymers, it sometimes feels sticky or slimy due to the thickener when used. In addition, it has insufficient spreadability on dry skin.

[0006] Furthermore, Patent Document 2 discloses a transparent gel-like detergent composition that uses a fatty acid potassium salt and a specific amide amino acid type amphoteric surfactant as a method for thickening by forming a complex through electrostatic interaction between an anionic surfactant and an amphoteric surfactant, and describes that this detergent composition foams and has excellent foam quality. However, Patent Document 2 does not mention at all about a method of use that does not generate foam, and it sometimes takes a long time to complete rinsing.

[0007] In addition to the non-lathering method, when dirt is particularly a concern, a method of use in which the gel is spread on the skin to lift the dirt, then water is added and the gel is lathered on the skin to wash is also desired, as this method allows the dirt to be washed away without re-adhering, providing a feeling of cleansing.

[0008] Therefore, there has been a demand for a gel-type skin cleanser that is less likely to drip from the tube container, spreads easily even on dry skin, is easy to rinse off when used without lathering, lathers well on the skin when used with lathering, and has a transparent appearance; however, it is extremely difficult to achieve these requirements, and it cannot be said that a product that satisfies these requirements has been provided. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-229638 [Patent Document 2] Japanese Patent Application Publication No. 11-189788 Summary of the Invention [Problem to be solved by the invention]

[0010] To provide a gel-type skin cleanser which is less likely to drip from a tube container, spreads easily even on dry skin, is easily rinsed off when used without lathering, and lathers well on the skin when used with lathering, and has a good transparency in appearance. [Means for solving the problem]

[0011] As a result of extensive research into solving the above problems, the inventors discovered that the above problems could be solved by a gel-type skin cleanser containing the components (a) to (c) described below in specific proportions, and thus completed the present invention. That is, the present invention is as follows.

[0012] A gel-type skin cleanser containing the following components (a), (b), and (c), with component (a) being 7 to 25% by mass, component (b) being 4 to 15% by mass, and component (c) being 0.001 to 0.5% by mass, with the total of components (a) and (b) being 15 to 35% by mass. Component (a): Potassium salt of fatty acid having 12 to 18 carbon atoms Component (b): an amphoteric surfactant represented by the following formula (1): [ka] (In formula (1), R 1 represents an alkyl group having 8 to 22 carbon atoms or an alkenyl group having 8 to 22 carbon atoms, and R 2 and R 3 each independently represents a methyl group or an ethyl group. Component (c): A polymer having 2-methacryloyloxyethyl phosphorylcholine and alkyl methacrylate as constituent monomers. [Effects of the Invention]

[0013] The gel-type skin cleanser of the present invention has the following effects: it is less likely to drip from a tube container, it spreads easily even on dry skin, it is easily rinsed off when used without lathering, it lathers well on the skin when used after lathering, and it has good transparency in appearance. In this specification, the term "tube container" refers to a generally cylindrical container having a hollow structure, which is squeezable and has a lid that closes the opening of the tube container. The tube container is made of one or more materials selected from plastic, aluminum, tin, etc., and may also be laminated. The size of the tube container is not particularly limited, but it is preferable that the opening diameter is 2 to 10 mm and the capacity is 10 to 500 mL. The term "transparent" means that no sediment, cloudiness, sediment, etc. are visible, and includes not only colorless transparency but also colored transparency. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described. The gel-type skin cleanser of the present invention contains the following components (a), (b), and (c), each of which will be described below. The term "gel-like" refers to a semi-solid state having fluidity, and the term "skin" refers to the body surface of the head, neck, trunk, arms, and legs, including the face. In this specification, numerical ranges defined using the symbol "to" are inclusive of the numerical values ​​at both ends (upper and lower limits) of the symbol "to." For example, "2 to 5" means 2 or more and 5 or less. The content of each component is expressed as a percentage by mass when the total amount of the gel skin cleanser is taken as 100% by mass.

[0015] [Component (a): Potassium salt of fatty acid having 12 to 18 carbon atoms] Component (a) used in the present invention is a potassium salt of a fatty acid having 12 to 18 carbon atoms. The fatty acid used in the potassium salt of a fatty acid is a saturated or unsaturated fatty acid, and an even-numbered fatty acid having 12 to 18 carbon atoms is preferred. Examples of such fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid. One selected from these fatty acids can be used alone, or two or more can be used in combination.

[0016] When two or more fatty acid potassium salts are used as component (a), the content of potassium laurate is preferably 10 to 55% by mass, more preferably 20 to 40% by mass, relative to the total content of the fatty acid potassium salts having 12 to 18 carbon atoms used as component (a) being 100% by mass. The content of potassium myristate is preferably 20 to 60% by mass, more preferably 30 to 50% by mass. The content of potassium palmitate is preferably 5 to 40% by mass, more preferably 10 to 30% by mass. Furthermore, the total content of potassium laurate, potassium myristate, and potassium palmitate is preferably 90 to 100% by mass, more preferably 95 to 100% by mass.

[0017] Component (a) used in the present invention is preferably a system containing free fatty acids (over-fat). Methods for preparing a system containing free fatty acids in component (a) include, for example, 1) preparing a fatty acid potassium salt and then adding a fatty acid thereto, and 2) reducing the amount of alkaline agent added when reacting the fatty acid with the alkaline agent, leaving unreacted free fatty acid. In the present invention, the amount of alkaline agent such as potassium hydroxide used is preferably 0.90 to 0.98 equivalents, more preferably 0.92 to 0.96 equivalents, relative to the fatty acid. When the alkaline agent content is within the above range, a gel-type skin cleanser can be obtained that exhibits excellent properties, such as no dripping from the tube container, ease of spread on dry skin, and excellent foaming on the skin.

[0018] In the present invention, the content of component (a) is 7 to 25% by mass, preferably 9 to 23% by mass, and more preferably 11 to 20% by mass, based on the total mass of the gel skin cleanser. If the content of component (a) is too low, the lack of dripping from the tube container and insufficient lathering on the skin may occur. On the other hand, if the content of component (a) is too high, the ease of spreading on dry skin and the transparency of the appearance may become insufficient.

[0019] [Component (b): Amphoteric surfactant] The component (b) used in the present invention is an alkylhydroxysulfobetaine-type amphoteric surfactant represented by formula (1).

[0020] [ka]

[0021] R in formula (1) 1 represents an alkyl group having 8 to 22 carbon atoms or an alkenyl group having 8 to 22 carbon atoms. The number of carbon atoms in each of the alkyl group and the alkenyl group is preferably 8 to 18. The alkyl group and the alkenyl group may be either linear or branched, and may be not only an alkyl group or an alkenyl group derived from a saturated hydrocarbon or an unsaturated hydrocarbon, but also an alkyl group or an alkenyl group derived from a mixed hydrocarbon containing two or more of these hydrocarbons. In addition, R 1 When is an alkyl or alkenyl group derived from a hydrocarbon mixture, the average carbon number calculated from the carbon numbers of the various hydrocarbons constituting the hydrocarbon mixture may be within the above range.

[0022] Examples of such alkyl or alkenyl groups include lauryl, myristyl, palmityl, stearyl, oleyl, arachidyl, and behenyl groups. Also usable are alkyl or alkenyl groups derived from mixed fats and oils, such as coconut oil alkyl groups, palm kernel oil alkyl groups, and beef tallow alkyl groups. Lauryl, myristyl, coconut oil alkyl groups, and palm kernel oil alkyl groups are preferred.

[0023] R in formula (1) 2 and R 3 are each independently a methyl group or an ethyl group. Preferably, R 2 and R 3 All of these are methyl groups.

[0024] Specific examples of the alkylhydroxysulfobetaine represented by formula (1) include laurylhydroxysulfobetaine and cocohydroxysulfobetaine. In the present invention, the component (b) can be one selected from the compounds encompassed by the above formula (1) or two or more selected and used appropriately. Specific examples of the component (b) include the product name "Nissan Anon (registered trademark) L-SB" (manufactured by NOF Corporation, R in the above formula (1) 1 : Lauryl group, R 2 and R 3 : methyl group].

[0025] In the present invention, the content of component (b) is 4 to 15% by mass, preferably 5 to 13% by mass, and more preferably 6 to 11% by mass, based on the total amount of the gel skin cleanser. If the content of component (b) is too low, the lack of dripping from the tube container and insufficient lathering on the skin may occur. On the other hand, if the content of component (b) is too high, the lack of dripping from the tube container, ease of spread on dry skin, ease of rinsing when used without lathering, and transparency of appearance may become insufficient. When multiple amphoteric surfactants represented by formula (1) are used in combination, the total amount of these multiple surfactants may be within the range of the content of component (b) above.

[0026] [Component (c): Polymer having 2-methacryloyloxyethyl phosphorylcholine and alkyl methacrylate as constituent monomers] Component (c) used in the present invention is a polymer containing 2-methacryloyloxyethyl phosphorylcholine and alkyl methacrylate as constituent monomers. Specifically, it is a polymer obtained by copolymerizing 2-methacryloyloxyethyl phosphorylcholine and alkyl methacrylate, and the molar ratio of 2-methacryloyloxyethyl phosphorylcholine to alkyl methacrylate in the polymer is preferably 1:0.2 to 1:3 (2-methacryloyloxyethyl phosphorylcholine: alkyl methacrylate). Examples of the alkyl group in the alkyl methacrylate include linear alkyl groups having 1 to 6 carbon atoms, specifically methyl, ethyl, propyl, butyl, pentyl, and hexyl groups, with butyl being preferred. Component (c) may be a polymer obtained by copolymerizing a monomer mixture containing, in addition to 2-methacryloyloxyethyl phosphorylcholine and alkyl methacrylate, other copolymerizable monomers as constituent monomers, and in this case, the proportion of the other monomers relative to 100 mol% of the monomer mixture is preferably 10 mol% or less. The other copolymerizable monomers are not particularly limited as long as the polymer as component (c) does not impair the effects of the present invention.

[0027] The weight average molecular weight of the polymer of component (c) is preferably 10,000 to 2,000,000, and more preferably 100,000 to 1,000,000. The weight average molecular weight can be measured by gel permeation chromatography.

[0028] A specific example of a polymer having 2-methacryloyloxyethyl phosphorylcholine and alkyl methacrylate as constituent monomers is the product name "LIPIDURE (registered trademark)-PMB" (manufactured by NOF Corporation, 80 mol % 2-methacryloyloxyethyl phosphorylcholine, 20 mol % butyl methacrylate, weight average molecular weight: 600,000).

[0029] In the present invention, the content of component (c) is 0.001 to 0.5% by mass, preferably 0.005 to 0.3% by mass, and more preferably 0.01 to 0.1% by mass, relative to the total amount of the gel skin cleanser. If the content of component (c) is too low, the ease of spreading on dry skin and the ease of rinsing off when used without lathering may be insufficient. On the other hand, if the content of component (c) is too high, the lathering on the skin and the transparency of the appearance may be insufficient.

[0030] [Total content of component (a) and component (b)] In the present invention, the total content of components (a) and (b) is 15 to 35% by mass, preferably 18 to 32% by mass, and more preferably 20 to 30% by mass, based on the total amount of the gel skin cleanser. If the total content of components (a) and (b) is too low, the product may not drip from the tube container and may not lather well on the skin. If the total content is too high, the product may not be easily rinsed off when used without lathering, and the transparency of its appearance may be insufficient.

[0031] [Mass ratio of the content of component (b) to component (a)] In the present invention, the mass ratio (b) / (a) of the content of component (b) to component (a) is preferably 1 / 3 to 3 / 2, more preferably 1 / 2 to 1 / 1. When the mass ratio (b) / (a) is within the above range, the absence of dripping from the tube container, ease of rinsing when used without lathering, and transparency of appearance are all further improved.

[0032] 〔water〕 The gel-type skin cleanser of the present invention typically contains water in addition to the above-mentioned components (a) to (c). The water used in the gel-type skin cleanser of the present invention may be purified water such as ion-exchanged water or distilled water, or any other water suitable for producing skin cleansers. In the present invention, the content of water is generally 60 to 85% by mass, preferably 65 to 83% by mass, and more preferably 70 to 80% by mass, based on the total amount of the gel skin cleanser.

[0033] [Other ingredients] The gel-type skin cleanser of the present invention may contain other ingredients in addition to the above-mentioned ingredients (a) to (c) within the scope that does not impair the effects of the present invention. The other ingredients are those commonly used in skin cleansers, such as 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, UV absorbers, UV scattering agents, vitamins, amino acids such as arginine, pigments, and fragrances. When the gel skin cleanser of the present invention contains such other ingredients, the content thereof is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total amount of the gel skin cleanser.

[0034] [Production of gel-type skin cleanser] The gel-type skin cleanser of the present invention can be produced by a known method. For example, a potassium salt of a fatty acid having 12 to 18 carbon atoms as component (a) is mixed with water and heated to melt, and then an amphoteric surfactant as component (b) is added and mixed. A water-soluble polymer as component (c) and other components blended as needed are further added and mixed uniformly, and the mixture is stirred and cooled to about room temperature to produce the gel-type skin cleanser of the present invention. [Example]

[0035] The following examples and comparative examples will be used to explain the embodiments of the present invention in more detail, but the present invention is not limited to these examples. The gel skin cleansing agents of Examples 1 to 12 and Comparative Examples 1 to 7, in which each ingredient was blended at the content shown in Tables 2 and 3, were evaluated by the following evaluation methods. The components used in the examples and comparative examples are as follows. The contents of components (b) and (c) shown in Tables 2 and 3 are converted contents of the target components contained in the formulations used.

[0036] [Component (a)] Fatty acid potassium salts (a1) to (a3) ​​prepared by mixing fatty acid salts according to the formulations shown in Table 1 below were used as component (a).

[0037] [Table 1]

[0038] [Component (b)] Alkylhydroxysulfobetaine: "Nissan Anon (registered trademark) L-SB" manufactured by NOF Corporation (30% by mass of laurylhydroxysulfobetaine, 70% by mass of water)

[0039] [Component (c)] Acrylic polymer: NOF Corporation's "LIPIDURE (registered trademark)-PMB" (polymer 5% by mass, water 95% by mass)

[0040] <Evaluation method> (1) Dripping from tube containers The gel skin cleanser was filled to approximately 80% of the volume (approximately 32 g) in a plastic tube container (5 mm diameter, 40 mL capacity), the lid was closed, and the container was left to stand in a thermostatic bath at 25°C. After 30 minutes, the container was removed from the thermostatic bath and, with the tube container's opening facing downwards, the lid was opened and the container was left to stand for 1 minute. The condition was observed from the side and evaluated as follows: ◎: No contents came out of the tube container. ○: A small amount of the contents comes out of the tube container, but does not drip. △: The contents drip slightly from the tube container. ×: The contents drip from the tube container.

[0041] (2) Ease of spreading on dry skin Twenty male and female panelists took 1g of the gel skin cleanser into their dry hands, spread it on their faces, and judged the ease of spreading it according to the following criteria. 2 points: If it feels very stretchy. 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 are 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 there were no panelists who gave a score of 0. △: The total score is between 20 and 30 points, or the total score is 30 or more points but there is a panelist who gave a score of 0. ×: The total score is less than 20 points.

[0042] (3) Ease of rinsing when used without lathering Twenty male and female panelists took 1g of the gel skin cleanser in their hands, spread it over their faces, left it for 1 minute, and then rinsed it off with lukewarm water. The ease of rinsing was judged according to the following criteria. 2 points: If you feel it is very easy to wash off. 1 point: If you feel it is somewhat easy to wash off. 0 points: If you find it difficult to rinse off. The total scores of the 20 people were calculated and evaluated according to the following criteria, and are 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 there were no panelists who gave a score of 0. △: The total score is between 20 and 30 points, or the total score is 30 or more points but there is a panelist who gave a score of 0. ×: The total score is less than 20 points.

[0043] (4) Foaming on the skin Twenty male and female panelists took 1g of the gel skin cleanser in their hands, spread it over their faces, left it for one minute, and then added lukewarm water to create a lather on their skin. The quality of the lather was judged according to the following criteria. 2 points: If you feel that it foams very well. 1 point: If you feel that the foam is slightly good. 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 are 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 there were no panelists who gave a score of 0. △: The total score is between 20 and 30 points, or the total score is 30 or more points but there is a panelist who gave a score of 0. ×: The total score is less than 20 points.

[0044] (5) Transparency of appearance After producing the gel skin cleanser, 50 mL (6 cm high) was filled into a hard, transparent glass bottle (55 mL capacity) with a height of 8 cm and a diameter of 3 cm, and the letters (font size: approximately 11 points) placed on the bottom of the glass bottle were evaluated based on how easily they could be read when viewed from above. If the letters were easy to read, the bottle was rated as "good transparency," if the letters were difficult to read or if sediment, cloudiness, sediment, etc. were visible, the bottle was rated as "no transparency," and if any other cases were observed, the bottle was rated as "slightly poor transparency." ○: Good transparency △: Transparency is slightly poor ×: No transparency

[0045] [Table 2]

[0046] [Table 3]

[0047] As shown in Table 2, each of the gel skin cleansers of Examples 1 to 12 was evaluated as a gel skin cleanser that did not drip from the tube container, spread easily even on dry skin, was easy to rinse off when used without lathering, and foamed well on the skin when used with lathering, and had a good appearance transparency. In particular, the gel skin cleanser of Example 1, which contains 16% 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.

[0048] On the other hand, as shown in Table 3, none of the gel skin cleansers of Comparative Examples 1 to 7 were found to be sufficiently effective in any of the evaluation items, as shown below. For example, the gel skin cleanser of Comparative Example 1, which did not contain a sufficient amount of component (a), was evaluated as dripping from the tube container, being difficult to rinse off when used without lathering, and not foaming well on the skin, even though the total content of components (a) and (b) and the content of component (c) were sufficient. In contrast, in Comparative Example 2, in which the content of component (a) was excessive, the ease of spread on dry skin and the transparency of appearance were evaluated as insufficient, even though the total content of components (a) and (b) and the content of component (c) were sufficient.

[0049] In Comparative Example 3, which did not contain a sufficient amount of component (b), even though the total content of components (a) and (b) and the content of component (c) were sufficient, dripping from the tube container, foaming on the skin, and transparency of appearance were evaluated as insufficient. On the other hand, in Comparative Example 4, in which the content of component (b) was excessive, even though the total content of components (a) and (b) and the content of component (c) were sufficient, dripping from the tube container, ease of spreading on dry skin, ease of rinsing when used without lathering, and transparency of appearance were evaluated as insufficient.

[0050] In Comparative Example 5, which did not contain a sufficient amount of component (c), even though the individual and total contents of components (a) and (b) were sufficient, the product was evaluated as being insufficient in terms of ease of spreading on dry skin and ease of rinsing off when used without lathering. In contrast, in Comparative Example 6, in which the content of component (c) was excessive, the foaming on the skin and the transparency of the appearance were evaluated as insufficient, even though the individual contents and the total contents of components (a) and (b) were sufficient.

[0051] In Comparative Example 7, in which the total content of components (a) and (b) was excessive, even though the contents of each of components (a) to (c) were sufficient, the ease of spreading on dry skin, the ease of rinsing when used without lathering, and the transparency of appearance were evaluated as insufficient. [Industrial Applicability]

[0052] The gel-type skin cleanser of the present invention can be used not only in the bath but also outside the bath, such as when washing the face in the morning, and can also meet the needs of users who are conscious of saving time.

Claims

[Claim 1] A gel-type skin cleanser containing the following components (a), (b), and (c), with component (a) being 7 to 25% by mass, component (b) being 4 to 15% by mass, and component (c) being 0.001 to 0.5% by mass, and the total of components (a) and (b) being 15 to 35% by mass. Component (a): Potassium salt of a fatty acid having 12 to 18 carbon atoms Component (b): an amphoteric surfactant represented by the following formula (1): 【Chemical 1】 (In formula (1), R １ represents an alkyl group having 8 to 22 carbon atoms or an alkenyl group having 8 to 22 carbon atoms, and R ２ and R ３ each independently represents a methyl group or an ethyl group. Component (c): A polymer having 2-methacryloyloxyethyl phosphorylcholine and alkyl methacrylate as constituent monomers.

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