Solid bath additives

Abstract

To provide a solid bath agent that has a rich sense of cuticular care, gives a good skin touch during bathing, which lasts even after bathing, and can suppress the bubbling of the bath water surface.SOLUTION: A solid bath agent contains a component (A): a carbonate, a component (B): an oil solution that is liquid at 25°C, a component (C): an ethylene oxide-added nonionic surfactant, and a component (D): a cellulose derivative. The mass ratio of the component (A) to the component (B) [(A) / (B)] is 80 or more and 250 or less, and the mass ratio of the component (A) to the component (D) [(A) / (D)] is 100 or more and 300 or less. The content of the component (C) is 0.1 mass% or more and 0.8 mass% or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a solid bath additive. [Background technology]

[0002] It is known that solid bath additives containing carbonates and organic acids generate carbon dioxide gas in bath water, which not only gives a fizzing sensation while bathing, but also warms the body and promotes blood circulation. Furthermore, solid bath additives with various functions have been proposed. Patent Document 1 discloses that a two-component bath agent consisting of a bath agent composition containing a carbon dioxide gas generating substance and a bath agent composition containing an oily component provides an extremely strong feeling of warmth after bathing, is pleasant to the touch on the skin, and also has good storage stability. Patent Document 2 discloses that a bath agent composition containing an organic acid, a carbonate, a nonionic surfactant with an average HLB of 11 or more, and an alcohol having 6 or more carbon atoms, in which the mass ratio of the nonionic surfactant to the alcohol having 6 or more carbon atoms is within a specified range, produces extremely fine bubbles on the bath water surface while increasing the persistence of the bubbles, and can provide a skin care effect on the skin for a long period of time. Patent Document 3 discloses that a bath agent composition containing an organic acid, a carbonate, a nonionic surfactant, an oil, and l-menthol or a derivative thereof can generate carbon dioxide gas in bath water and provide a pleasant cooling sensation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-314233 A [Patent Document 2] JP 2015-231963 A [Patent Document 3] JP 2019-131620 A Summary of the Invention [Problem to be solved by the invention]

[0004] The bath additives disclosed in Patent Documents 1 to 3 all generate carbon dioxide gas in bath water. On the other hand, studies are being conducted on bath additives that do not generate carbon dioxide gas, in order to impart beauty effects such as improving sweating and metabolism, improving skin moisture and transparency, and removing dead skin cells, thereby making them high-added value products. In recent years, young women have been in high demand for bath additives with beauty care effects. In particular, there is a high demand for exfoliating care, but many consumers do not perform exfoliating care because it is troublesome and it is difficult to care for hard-to-reach areas such as the back. Therefore, there is a demand for bath additives that allow full-body exfoliation just by bathing and provide a good skin feel during and after bathing, but there has not yet been a bath additive that meets these needs.

[0005] Furthermore, in bath additives that do not generate carbon dioxide, when surfactants are added, bubbles can become noticeable on the surface of the bath water, and there is a demand for improvement in this regard.

[0006] The present invention relates to a solid bath agent that has an keratin-care feel, provides a good skin feel during and after bathing, and can suppress foaming on the surface of bath water. [Means for solving the problem]

[0007] The present inventors have discovered that the above-mentioned problems can be solved by a solid bath additive containing a carbonate, a specified oil agent, a nonionic surfactant, and a cellulose derivative in specified proportions. That is, the present invention provides: Component (A): Carbonate, Component (B): An oil that is liquid at 25°C. Component (C): an ethylene oxide addition type nonionic surfactant, and Component (D): cellulose derivatives, The mass ratio of component (A) to component (B) [(A) / (B)] is 80 or more and 250 or less, the mass ratio of component (A) to component (D) [(A) / (D)] is 100 or more and 300 or less, and the content of component (C) is 0.1% by mass or more and 0.8% by mass or less. Effect of the Invention

[0008] According to the present invention, it is possible to provide a solid bath additive that has an keratin-care feel, provides a good skin feel during and after bathing, and can suppress foaming on the surface of bath water. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Solid bath additives] The solid bath agent of the present invention (hereinafter also simply referred to as "the bath agent of the present invention") is Component (A): Carbonate, Component (B): An oil that is liquid at 25°C. Component (C): an ethylene oxide addition type nonionic surfactant, and Component (D): cellulose derivatives, The mass ratio of component (A) to component (B) [(A) / (B)] is 80 or more and 250 or less, the mass ratio of component (A) to component (D) [(A) / (D)] is 100 or more and 300 or less, and the content of component (C) is 0.1 mass% or more and 0.8 mass% or less. By using the bath additive of the present invention in the above-mentioned composition, it has an keratin-care feel, provides a good skin feel during and after bathing, and can suppress foaming on the surface of bath water when dissolved in bath water.

[0010] <Definition> In the present invention, the term "solid" means that the substance is in a solid state at 25°C. The "feeling of exfoliation" refers to the feeling that the skin surface is aware of having had keratin removed, and more specifically, refers to the feeling that the palm of the hand feels slippery when checking the skin's texture during a bath (a tight feeling). "Good skin feel during bathing" means that the skin feels smooth (smooth feeling) while bathing, and "good skin feel after bathing" means that the skin does not feel overly dry (dry) when towel-dried after bathing. "Foaming on the surface of bath water" refers to foaming on the surface of bath water when a bath additive is added to bath water and stirred to dissolve it. The keratinizing feel, the skin feel during and after bathing, and the foaming on the surface of the bath water can be specifically evaluated by the methods described in the Examples.

[0011] Generally, by making the pH of bath water alkaline, a bath agent can be given a sebum-removing effect, but there are cases where excessive sebum is removed, which can lead to a decrease in the skin feel (smoothness) during bathing and a feeling of excessive dryness (dryness) of the skin after bathing. The bath agent of the present invention contains components (B), (C), and (D) in a specific content ratio, and although the reason is unclear, it is possible to achieve both a feeling of keratin care and a smooth feeling during bathing while suppressing foaming on the surface of the bath water, and also to suppress dryness of the skin after bathing due to the removal of sebum, thereby maintaining a good skin feel.

[0012] <Component (A): Carbonate> The bath agent of the present invention contains a carbonate as component (A). The bath agent containing a predetermined amount of component (A) can shift the pH of bath water into which it is added to the alkaline side, providing a feeling of keratin care.

[0013] From the viewpoint of shifting the bath water containing the bath agent to the alkaline side and improving the keratin care feeling, it is preferable that component (A) contains a dialkali metal carbonate. The dialkali metal carbonate may be one or more selected from the group consisting of sodium carbonate and potassium carbonate, and sodium carbonate is preferred from the viewpoint of making the bath water alkaline, improving the keratin care feeling, solubility in bath water and moldability, and from the viewpoint of economy. When component (A) contains a dialkali metal carbonate, the content of the dialkali metal carbonate in component (A) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more from the viewpoint of improving the keratin care feeling, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less from the viewpoint of suppressing dryness after bathing.

[0014] Examples of carbonates other than dialkali metal carbonates contained in the bath agent as component (A) include alkali metal bicarbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate; alkaline earth metal carbonates such as calcium carbonate and magnesium carbonate; alkaline earth metal bicarbonates such as calcium hydrogen carbonate; and the like, and one or more of these can be used. Among these, from the viewpoints of improving the keratin care feeling, suppressing dryness after bathing, formability, and cost, one or more selected from the group consisting of sodium hydrogen carbonate and calcium carbonate are preferred, and sodium hydrogen carbonate is more preferred.

[0015] <Component (B): Oil that is liquid at 25°C> The bath additive of the present invention contains, as component (B), an oily agent that is liquid at 25° C. (hereinafter, also simply referred to as "liquid oily agent").

[0016] Component (B) is not particularly limited as long as it is a liquid oil used in ordinary bath additives, and examples thereof include ester oil, higher fatty acid, higher alcohol, hydrocarbon oil, silicone oil, fluorine-based oil, etc., which are liquid at 25° C. These may be naturally derived oils such as vegetable oils and animal oils.

[0017] Examples of ester oils include fatty acid esters composed of fatty acids and monohydric or dihydric alcohols, glycerin fatty acid esters (glycerides) composed of fatty acids and glycerin, etc. The number of carbon atoms in the fatty acid is preferably 8 or more and 24 or less, more preferably 8 or more and 20 or less, and even more preferably 8 or more and 18 or less, from the viewpoints of obtaining a good skin feel during bathing and improving emulsification and dispersibility in bath water and uniformly dispersing the ester oil in bath water. Specific examples of ester oils used as component (B) include cetyl octanoate, cetyl isooctanoate, myristyl lactate, cetyl lactate, isopropyl myristate, myristyl myristate, isocetyl myristate, octyldodecyl myristate, isopropyl palmitate, isostearyl palmitate, isopropyl adipate, butyl stearate, isocetyl stearate, isotridecyl isononanoate, decyl oleate, cholesterol isostearate, butyl laurate, isoa laurate, and the like. Fatty acid esters such as myristic acid, methyl myristate, ethyl myristate, ethyl stearate, isononyl isononanoate, isopropyl linoleate, isostearyl isostearate, isopropyl isostearate, methyl oleate, ethyl oleate, oleyl oleate, and ethyl 2-ethylhexanoate; glycerin fatty acid esters (glycerides) such as tri(caprylic acid / capric acid)glycerin, triglyceryl caprylate, myristate glyceride, and 2-ethylhexanoate glyceride; and the like.

[0018] Examples of higher fatty acids include fatty acids having 8 to 24 carbon atoms, such as oleic acid, linoleic acid, and linolenic acid. Examples of higher alcohols include alcohols having 8 to 24 carbon atoms, more preferably 8 to 18 carbon atoms, such as lauryl alcohol, oleyl alcohol, isostearyl alcohol, and 2-hexyldecanol. Examples of the hydrocarbon oil include linear or branched hydrocarbon oils that are liquid at 25°C, such as liquid paraffin, light liquid isoparaffin, squalane, and squalene. Examples of silicone oils include silicone oils that are liquid at 25°C, such as dimethylpolysiloxane, dimethylcyclopolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, and higher alcohol-modified silicone oil. Examples of fluorine-based oils include fluoropolyethers and perfluoroalkyl ether silicones that are liquid at 25°C.

[0019] Examples of vegetable oils include soybean oil, rice bran oil, jojoba oil, avocado oil, almond oil, olive oil, cacao butter, sesame oil, persic oil, castor oil, coconut oil, safflower oil, and oils obtained by hydrogenating these oils that are liquid at 25°C. Examples of animal oils include mink oil and liquid lanolin.

[0020] One or more kinds of component (B) can be used. Among the above, from the viewpoint of obtaining a good feel on the skin during bathing and improving emulsification and dispersibility in bath water, component (B) is preferably an ester oil, more preferably a glycerin fatty acid ester, and even more preferably tri(caprylic acid / capric acid)glycerin.

[0021] <Component (C): Ethylene oxide adduct type nonionic surfactant> The bath additive of the present invention contains an ethylene oxide addition type nonionic surfactant as component (C). Examples of component (C) include one or more selected from the group consisting of polyoxyethylene alkyl ethers, polyoxyethylene alkenyl ethers, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbit fatty acid esters, polyoxyethylene fatty acid esters, and polyoxyethylene hydrogenated castor oil.

[0022] From the viewpoint of improving the emulsification dispersibility of component (B) in bath water and uniformly dispersing component (B) in bath water, the average number of moles of ethylene oxide added in component (C) (hereinafter referred to as "average number of moles of EO added") is preferably 2 or more, more preferably 3 or more, even more preferably 5 or more, and is preferably 150 or less, more preferably 80 or less, even more preferably 60 or less, and still more preferably 50 or less. The average number of moles of EO added is a number average value.

[0023] Furthermore, among the nonionic surfactants, the alkyl group in the polyoxyethylene alkyl ether, the alkenyl group in the polyoxyethylene alkenyl ether, and the fatty acids in the polyoxyethylene sorbitan fatty acid ester, the polyoxyethylene sorbit fatty acid ester, and the polyoxyethylene fatty acid ester preferably have 8 or more and 22 or less carbon atoms, more preferably 10 or more and 22 or less carbon atoms, and even more preferably 12 or more and 20 or less carbon atoms, from the viewpoint of improving the emulsification dispersibility of component (B) in bath water and uniformly dispersing component (B) in bath water.

[0024] Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene behenyl ether. A specific example of the polyoxyethylene alkenyl ether is polyoxyethylene oleyl ether. The alkyl group or alkenyl group constituting the polyoxyethylene alkyl ether or polyoxyethylene alkenyl ether preferably has 8 or more and 22 or less carbon atoms, more preferably 10 or more and 22 or less carbon atoms, and even more preferably 12 or more and 20 or less carbon atoms, from the viewpoint of improving the emulsifiable dispersibility of component (B) in bath water and uniformly dispersing component (B) in bath water. Specific examples of polyoxyethylene sorbitan fatty acid esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan dilaurate, polyoxyethylene sorbitan trilaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene coconut oil fatty acid sorbitan, and the like. Specific examples of polyoxyethylene sorbitol fatty acid esters include polyoxyethylene sorbitol monolaurate, polyoxyethylene sorbitol mono-, di-, tri-, or tetra-oleate, and polyoxyethylene sorbitol mono-, di-, tri-, or tetra-stearate. Specific examples of polyethylene glycol fatty acid esters include polyethylene glycol mono- or dilaurate, polyethylene glycol mono- or dioleate, and polyethylene glycol mono- or distearate. The number of carbon atoms in the fatty acid-derived constituent units constituting the polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbit fatty acid ester, and polyethylene glycol fatty acid ester is preferably 8 or more and 22 or less, more preferably 10 or more and 22 or less, and even more preferably 12 or more and 20 or less, from the viewpoint of improving the emulsifiable dispersibility of component (B) in bath water and uniformly dispersing component (B) in the bath water.

[0025] The component (C) can be used alone or in combination of two or more. Among the above, from the viewpoint of improving the emulsification and dispersibility of component (B) in bath water and dispersing component (B) uniformly in bath water, component (C) is preferably one or more selected from the group consisting of polyoxyethylene alkyl ethers, polyoxyethylene alkenyl ethers, polyoxyethylene sorbitol fatty acid esters, and polyoxyethylene fatty acid esters, more preferably one or more selected from the group consisting of polyoxyethylene alkyl ethers, polyoxyethylene alkenyl ethers, and polyoxyethylene sorbitol fatty acid esters, even more preferably one or more selected from the group consisting of polyoxyethylene alkyl ethers and polyoxyethylene sorbitol fatty acid esters, and even more preferably one or more selected from the group consisting of polyoxyethylene stearyl ether and polyoxyethylene sorbitol tetraoleate. Even more preferably, component (C) contains both polyoxyethylene stearyl ether and polyoxyethylene sorbitol tetraoleate.

[0026] Commercially available products of component (C) include "Emulgen 108" (polyoxyethylene (6) lauryl ether), "Emulgen 116" (polyoxyethylene (16) lauryl ether), "Emulgen 123P" (polyoxyethylene (23) lauryl ether), "Emulgen 306P" (polyoxyethylene (6) stearyl ether), "Emulgen 420" (polyoxyethylene (13) oleyl ether), "Rheodol 440V" (polyoxyethylene sorbitol tetraoleate (40 E.O.)), "Rheodol 460V" (polyoxyethylene sorbitol tetraoleate (60 E.O.)), and "NIKKOL GO-430NV" (polyoxyethylene sorbitol tetraoleate (30 E.O.)) and "NIKKOL GO-460NV" (polyoxyethylene sorbitol tetraoleate (60 E.O.)), all manufactured by Kao Corporation.

[0027] <Component (D): Cellulose derivative> The bath additive of the present invention contains a cellulose derivative as component (D). As the cellulose derivative, any of nonionic cellulose derivatives, anionic cellulose derivatives, and cationic cellulose derivatives can be used. Examples of the nonionic cellulose derivatives include alkyl celluloses such as methyl cellulose and ethyl cellulose; hydroxyalkyl celluloses such as hydroxyethyl cellulose and hydroxypropyl cellulose; hydroxypropyl methyl cellulose, and ethyl hydroxyethyl cellulose. Anionic cellulose derivatives include carboxymethyl cellulose. Examples of the cationic cellulose derivatives include cationic cellulose, cationic ethyl cellulose, cationic hydroxyethyl cellulose, and cationic hydroxypropyl cellulose.

[0028] One or more kinds of component (D) can be used. Among the above, from the viewpoint of maintaining a good skin feel after bathing, component (D) is preferably one or more kinds selected from the group consisting of nonionic cellulose derivatives and anionic cellulose derivatives, and more preferably nonionic cellulose derivatives. Among the nonionic cellulose derivatives, from the viewpoint of maintaining a good feel on the skin after bathing and from the viewpoint of solubility in bath water, hydroxyalkyl cellulose is preferred, and hydroxyethyl cellulose is more preferred. The number of carbon atoms in the alkyl group constituting the hydroxyalkyl cellulose is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and even more preferably 1 or more and 2 or less, from the viewpoint of maintaining a good feel on the skin after bathing.

[0029] Commercially available products of component (D) include the HEC "SP" series, "SE" series, and "EE" series (all hydroxyethyl cellulose) and the CMC Daicel series (carboxymethyl cellulose) manufactured by Daicel Miraize Co., Ltd., "Ucare Polymer JR-400" manufactured by The Dow Chemical Company, and "Poise C-60H," "Poise C-150L," and "Cacicero M-80" (all cationized hydroxyethyl cellulose) manufactured by Kao Corporation.

[0030] <Other ingredients> The bath additive of the present invention may contain other components that are normally used in bath additives. Examples of such components include inorganic salts other than component (A), such as sodium sulfate, magnesium sulfate, magnesium oxide, potassium chloride, sodium chloride, potassium nitrate, sodium nitrate, sodium polyphosphate, sodium metaphosphate, ammonium chloride, iron sulfate, sodium phosphate, and sodium thiosulfate; water-soluble polymers other than component (D), such as polyethylene glycol and dextrin; excipients such as calcium silicate and glucose; opacifiers such as titanium oxide; disintegration aids; medicinal ingredients such as herbal medicines; colorants; and fragrances.

[0031] <Content> The content of each component in the bath agent of the present invention is preferably within the following ranges from the viewpoints of providing an keratin-care feeling, a good skin feel during and after bathing, and suppressing foaming on the surface of the bath water.

[0032] The content of component (A) in the bath agent of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more from the viewpoint of improving the keratin care feeling. Also, from the viewpoint of suppressing the dry feeling after bathing, it is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. Furthermore, when the bath additive contains a dialkali metal carbonate as component (A), the content of the dialkali metal carbonate in the bath additive is preferably 15% by mass or more, and more preferably 18% by mass or more, from the viewpoint of improving the keratin care feeling, and is preferably 30% by mass or less, more preferably 28% by mass or less, and even more preferably 26% by mass or less, from the viewpoint of suppressing the dry feeling after bathing and improving the skin feel.

[0033] From the viewpoint of obtaining a good feel on the skin while bathing, the content of component (B) in the bath additive is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, and from the viewpoint of emulsifiable dispersibility in bath water, the content is preferably 3% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less, and even more preferably 0.8% by mass or less.

[0034] The content of component (C) in the bath additive is 0.1% by mass or more, preferably 0.15% by mass or more, more preferably 0.20% by mass or more, and even more preferably 0.25% by mass or more, from the viewpoint of improving the emulsification and dispersibility of component (B) in the bath water. Also, from the viewpoint of suppressing foaming on the bath water surface, the content is 0.8% by mass or less, preferably 0.6% by mass or less, more preferably 0.45% by mass or less, and even more preferably 0.40% by mass or less.

[0035] From the viewpoint of suppressing dryness after bathing and maintaining a good skin feel, the content of component (D) in the bath additive is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, even more preferably 0.4 mass% or more, and is preferably 2 mass% or less, more preferably 1.5 mass% or less, even more preferably 1 mass% or less, and even more preferably 0.6 mass% or less.

[0036] From the viewpoint of obtaining the effects of the present invention, the total content of components (A) to (D) in the bath additive is preferably 51% by mass or more, more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, and even more preferably 75% by mass or more, and particularly preferably 90% by mass or more.

[0037] In the bath additive of the present invention, the mass ratio of component (A) to component (B) [(A) / (B)] is, from the viewpoint of achieving both a keratin care feeling and a good skin feel during bathing, at least 80, preferably at least 85, more preferably at least 90, and even more preferably at least 95. In addition, it is at most 250, preferably at most 220, more preferably at most 200, even more preferably at most 180, and even more preferably at most 160.

[0038] In the bath additive of the present invention, the mass ratio of component (A) to component (D) [(A) / (D)] is 100 or more, preferably 120 or more, and more preferably 125 or more, from the viewpoint of imparting a feeling of keratin care while suppressing dryness after bathing and maintaining a good skin feel, and is also 300 or less, preferably 250 or less, more preferably 200 or less, and even more preferably 180 or less.

[0039] In the bath additive of the present invention, the mass ratio of component (C) to component (B) [(C) / (B)] is preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.35 or more, and even more preferably 0.38 or more, from the viewpoint of suppressing foaming on the bath water surface and improving the emulsification and dispersibility of component (B) in the bath water. Also, it is preferably 0.7 or less, more preferably 0.68 or less, even more preferably 0.65 or less, and even more preferably 0.63 or less.

[0040] From the viewpoint of providing a good keratin care feeling, the bath agent of the present invention preferably does not generate carbon dioxide gas in the bath water, and from this viewpoint, it is preferable that the content of organic acid is small. Examples of organic acids include carboxylic acid compounds, organic sulfonic acid compounds, and organic phosphoric acid compounds. The content of these organic acids in the bath agent is preferably 1% by mass or less, more preferably 0.1% by mass or less, even more preferably 0.05% by mass or less, and even more preferably 0% by mass.

[0041] The bath agent of the present invention may contain a surfactant other than component (C) to the extent that the effect of the present invention is not impaired, but from the viewpoint of suppressing foaming on the bath water surface, it is preferable that the content of surfactant other than component (C) is small. The content of surfactant other than component (C) in the bath agent of the present invention is preferably 1 mass % or less, more preferably 0.5 mass % or less, even more preferably 0.1 mass % or less, and even more preferably 0.01 mass % or less. From a similar viewpoint, the content of component (C) in the nonionic surfactant in the bath additive of the present invention is preferably 98% by mass or more, more preferably 99% by mass or more, more preferably 99.5% by mass or more, and even more preferably essentially 100% by mass.

[0042] <Dosage form, manufacturing method> The dosage form (product form) of the solid bath agent of the present invention when used may be powder, tablet, etc., but powder is preferable from the viewpoint of good solubility in a bathtub. Tablets include compressed tablets and briquettes, and compressed tablets are more preferable from the viewpoint of moldability. The method for producing the bath agent of the present invention is not limited, and the bath agent can be produced according to a conventional method. When the bath agent is a tablet or briquette type agent, the bath agent can be produced according to a conventional method such as a compression molding method using a press tablet machine or a briquette machine.

[0043] <Properties> The bath agent of the present invention becomes a bath agent having a keratin-care feel by shifting the bath water to the alkaline side when added to the bath water. From the viewpoint of obtaining an excellent keratin-care feeling, the bath agent of the present invention preferably has a pH of 8 or more, more preferably 8.5 or more, and even more preferably 9 or more, at 40° C. in bath water in which 0.4 g of the bath agent is dissolved per liter of water. Moreover, from the viewpoint of suppressing irritation to the skin, the pH is preferably 10 or less, and more preferably 9.7 or less. From the viewpoint of obtaining an excellent keratin-care feeling, the pH of the bath water containing the bath agent of the present invention is preferably 8 or more, more preferably 8.5 or more, and even more preferably 9 or more. From the viewpoint of suppressing irritation to the skin, the pH is preferably 10 or less, and more preferably 9.7 or less. The pH of the bath water into which the bath additive has been added is preferably within the above range at the temperature of the bath water when taking a bath. The pH of the bath water can be specifically measured by the method described in the Examples. EXAMPLES

[0044] Examples 1 to 7 and Comparative Examples 1 to 4 (Production and Evaluation of Solid Bath Additives) Of the components shown in Table 1, component (B), component (C) and fragrance were extruded using calcium silicate in the amount shown in Table 1. The remaining components shown in Table 1 were then mixed to produce powdered solid bath additives. In addition, the skin feel, keratin care feel, foaming on the surface of the bath water, and pH during and after bathing were measured and evaluated using the methods described below. The results are shown in Table 1. The blended amounts (mass%) of each component shown in Table 1 are all active amounts.

[0045] <Skin feel during bathing (smooth feeling)> 60g of each solid bath additive was added to 150L of bath water at 40℃, and four expert panelists bathed in the bath for 10 minutes each. The skin feel (smooth feeling) in the bath within 2 minutes after bathing was evaluated according to the following criteria, and the average value was rounded off to the nearest whole number to obtain the evaluation value. The higher the evaluation value, the better the skin feel during bathing. 5: The smooth feeling is noticeable 4: Smooth feeling 3: Slightly smooth feeling 2: Less slippery 1: No smooth feeling

[0046] <Skin feel after bathing (less dryness)> 60g of each solid bath additive was added to 150L of bath water at 40°C, and four expert panelists bathed in the bath for 10 minutes each. After bathing, the skin was towel-dried and evaluated for feel according to the following criteria, and the average was rounded off to obtain the evaluation value. A higher evaluation value indicates less dryness and better feel on the skin after bathing. 5: No dryness at all 4: Almost no dryness 3: Less dryness (tolerable level for practical use) 2: Dryness is observed 1: Dryness is evident

[0047] <Exfoliating feel> 60g of each solid bath additive was added to 150L of bath water at 40℃, and four expert panelists bathed for 10 minutes each. After 2 minutes, the skin feel in the bath was evaluated according to the following criteria as to whether it changed from a smooth feeling to a feeling that the palm of the hand would slip (tight feeling), and the average value was rounded off to the nearest whole number to obtain the evaluation value. The higher the evaluation value, the better the exfoliation feeling. 5: The tightness is noticeable 4: It feels tight 3: Slightly tight 2: Less tight feeling 1: No tight feeling

[0048] <Foaming on the bath water surface> 60g of each solid bath additive was added to 150L of bath water at 40℃ and stirred to dissolve. The amount of foaming on the surface of the bath water was visually evaluated according to the following criteria, and the average value was rounded off to the nearest 1. A higher evaluation value means less foaming on the surface of the bath water, which indicates a better result. 5: No foaming observed at all 4: Almost no foaming observed 3: Low foaming (tolerable level for practical use) 2: Foaming is observed 1: Foaming is noticeable

[0049] <ph> 60 g of each solid bath additive was added to 150 L of bath water at 40°C, and the pH at the time of completion of dissolution was measured using a pH meter (HORIBA's "Portable pH Meter LAQUAact D-50"). In both the examples and the comparative examples, the pH was 9.5.

[0050] [Table 1]

[0051] *1: Tri(caprylic acid / capric acid)glycerin: "Coconard MT" manufactured by Kao Corporation *2: Polyoxyethylene sorbitol tetraoleate (40E.O.): "Rheodol 440V" manufactured by Kao Corporation *3: Polyoxyethylene (6) stearyl ether: Kao Corporation's "Emulgen 306P" *4: Hydroxyethyl cellulose: "HEC SE400" manufactured by Daicel Miraize Co., Ltd.

[0052] From Table 1, it can be seen that the solid bath agent of this Example is excellent in all of the following: keratin care feel, skin feel during and after bathing, and foaming suppression effect on the bath water surface. In contrast, the solid bath agent of this Comparative Example was inferior in all of the following: keratin care feel, skin feel during and after bathing, and foaming suppression effect on the bath water surface. [Industrial Applicability]

[0053] According to the present invention, it is possible to provide a solid bath additive that has an keratin-care feel, provides a good skin feel during and after bathing, and can suppress foaming on the surface of bath water.< / ph>

Claims

1. Component (A): Carbonate including dialkali metal carbonate, Component (B): An oil agent that is liquid at 25°C and contains an ester oil; Component (C): an ethylene oxide addition type nonionic surfactant containing at least one selected from the group consisting of polyoxyethylene alkyl ethers and polyoxyethylene sorbitol fatty acid esters, and Component (D): a cellulose derivative including a nonionic cellulose derivative, Contains the mass ratio of component (A) to component (B) [(A) / (B)] is 80 or more and 250 or less; the mass ratio of component (A) to component (D) [(A) / (D)] is 100 or more and 300 or less; A solid bath additive having a component (C) content of 0.1% by mass or more and 0.8% by mass or less.

2. 2. The solid bath additive according to claim 1, wherein the mass ratio [(A) / (D)] of the component (A) to the component (D) is 120 or more and 250 or less.

3. 3. The solid bath additive according to claim 1, wherein the mass ratio of component (C) to component (B) [(C) / (B)] is 0.3 or more and 0.68 or less.

4. The solid bath additive according to any one of claims 1 to 3, wherein the content of the component (A) is 50% by mass or more and 95% by mass or less.

5. The solid bath agent according to any one of claims 1 to 4, wherein the content of the dialkali metal carbonate in the solid bath agent is 15% by mass or more and 30% by mass or less.

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