Effervescent solid bath additives

Abstract

To provide a foamable solid bath agent that has excellent moldability and also excellent storage stability.SOLUTION: A foamable solid bath agent comprises following components (A)-(C): (A) at least one selected from the group consisting of alkali metal bicarbonate (A1) and alkali metal sulfate (A2), (B) dialkali metal carbonate and (C) organic acid. In the bath agent, the content of the component (B) is 16 mass% or more. The mass ratio of the content of the component (A) to the content of the component (B) in the bath agent [(A) / (B)] is 1.0 or more and 5.4 or less. In the bath agent, the content of a liquid oil-based component with a molecular weight of 300 or less is 0.1 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Solid bath additives containing carbonates and organic acids are known to generate carbon dioxide bubbles in bathwater, allowing users to enjoy the fizzing sensation, as well as to provide a warming sensation and blood circulation-promoting effects due to the carbon dioxide.

[0003] Fragrances are added to such effervescent solid bath additives to enhance the relaxing effect and other benefits of the fragrance. For example, Patent Document 1 discloses that foaming compression-molded bath additives contain terpene fragrances and liquid paraffin, with the liquid paraffin content being 0.05 to 3.0% by weight relative to the total amount of the bath additive. These bath additives release a pleasant fragrance immediately after dissolving in bathwater, allowing bathers to sense the pleasant fragrance immediately after bathing and achieve aromatherapy effects. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-66103 Summary of the Invention [Problem to be solved by the invention]

[0005] While such fragrant effervescent solid bath additives exist, in recent years, consumers who value a natural feel have been increasingly demanding a natural bathing experience similar to plain water, and there has been a demand for effervescent solid bath additives to contain less fragrance or to contain no fragrance at all. However, it has been found that reducing the amount of oily components such as fragrance from effervescent solid bath additives results in a problem of reduced productivity in the molding process. Furthermore, it has been found that attempts to improve the reduced productivity result in a further problem of worsening storage stability.

[0006] An object of the present invention is to provide a foaming solid bath additive that has excellent moldability and storage stability. [Means for solving the problem]

[0007] The present inventors conducted research to solve the problems of reduced productivity in the molding process and deteriorated storage stability when reducing oily ingredients such as fragrances. They focused on the balance between the amounts of at least one selected from the group consisting of alkali metal bicarbonate and alkali metal sulfate and a dialkali metal carbonate, and discovered that by setting the mass ratio of the content of at least one selected from the group consisting of alkali metal bicarbonate and alkali metal sulfate to the content of dialkali metal carbonate within a predetermined range and setting the content of the dialkali metal carbonate to a predetermined amount or more, it is possible to realize an effervescent solid bath additive that unexpectedly achieves both moldability and storage stability in a formulation with a reduced content of liquid oily ingredients with a molecular weight of 300 or less, thereby solving the above problems. That is, the present invention provides the following components (A) to (C): (A) at least one selected from the group consisting of alkali metal bicarbonates (A1) and alkali metal sulfates (A2); (B) Dialkali metal carbonate (C)Organic acid A foaming solid bath additive comprising: The content of component (B) in the bath additive is 16% by mass or more, the mass ratio [(A) / (B)] of the content of component (A) to the content of component (B) in the bath additive is 1.0 or more and 5.4 or less; The present invention relates to a foaming solid bath additive, in which the content of liquid oily components with a molecular weight of 300 or less in the bath additive is 0.1% by mass or less. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a foaming solid bath additive that has excellent moldability and storage stability. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Effervescent solid bath additives] The effervescent solid bath additive of the present invention (hereinafter also referred to simply as "the bath additive of the present invention") comprises the following components (A) to (C): (A) at least one selected from the group consisting of alkali metal bicarbonates (A1) and alkali metal sulfates (A2); (B) Dialkali metal carbonate (C)Organic acid A foaming solid bath additive comprising: The content of component (B) in the bath additive is 16% by mass or more, the mass ratio [(A) / (B)] of the content of component (A) to the content of component (B) in the bath additive is 1.0 or more and 5.4 or less; The content of liquid oily components with a molecular weight of 300 or less in the bath additive is 0.1% by mass or less. In the present invention, the term "foaming solid bath additive" refers to a solid bath additive that foams when added to bath water. In the present invention, "liquid" refers to a state that has fluidity at 1 atmosphere and 25°C. Furthermore, "oily component" refers to a component that has a solubility of less than 0.01 g in 100 g of water at 20°C.

[0010] By using the above-described composition, the bath additive of the present invention has excellent moldability and storage stability. The bath additive of the present invention contains at least component (B) a dialkali metal carbonate as a carbonate salt, and further contains component (C) an organic acid, and therefore, when added to bath water, carbon dioxide gas can be generated by the reaction between these carbonates and the organic acid. The bath additive contains at least one component selected from the group consisting of alkali metal bicarbonate (A1) and alkali metal sulfate (A2). Component (A) is a raw material with low powder-to-powder bonding strength, while component (B) dialkali metal carbonate has excellent hygroscopicity. Consequently, careful consideration was given to the blending ratios and amounts of these components. By setting the mass ratio of component (A) to component (B) in the bath additive [(A) / (B)] to be 1.0 or more and 5.4 or less, and by setting the content of component (B) in the bath additive to 16% by mass or more, it is possible to suppress sticking during molding when producing the bath additive, even when the content of liquid oily components with a molecular weight of 300 or less in the bath additive is 0.1% by mass or less. This also improves the storage stability of the bath additive, resulting in a balance between excellent moldability and excellent storage stability.

[0011] <Component (A): At least one selected from the group consisting of alkali metal bicarbonate (A1) and alkali metal sulfate (A2)> In order to improve formability, the bath additive of the present invention contains, as component (A), at least one selected from the group consisting of alkali metal bicarbonates (A1) and alkali metal sulfates (A2).

[0012] The alkali metal bicarbonate (A1) improves moldability, and when the bath additive of the present invention is added to bath water, it reacts with the component (C) described below to generate carbon dioxide gas, which promotes blood circulation and helps the bather warm up quickly. The alkali metal bicarbonate (A1) may be one or more selected from the group consisting of sodium hydrogen carbonate and potassium hydrogen carbonate. From the viewpoints of improving moldability, foaming property, and cost efficiency, it preferably contains sodium hydrogen carbonate, and more preferably is sodium hydrogen carbonate.

[0013] The alkali metal sulfate (A2) can improve moldability and can also impart the effect of improving the warming effect when taking a bath. The alkali metal sulfate (A2) may be one or more selected from the group consisting of sodium sulfate and potassium sulfate. From the viewpoint of improving moldability and economic efficiency, it preferably contains sodium sulfate, and more preferably is sodium sulfate.

[0014] From the viewpoint of improving moldability, the content of component (A) in the bath additive of the present invention is preferably 20% by mass or more, more preferably 23% by mass or more, even more preferably 25% by mass or more, even more preferably 28% by mass or more, even more preferably 30% by mass or more, and even more preferably 40% by mass or more; and from the viewpoints of storage stability, foaming properties, and solubility in bath water, the content is preferably 75% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less.

[0015] When component (A) contains an alkali metal bicarbonate (A1), the content of the alkali metal bicarbonate (A1) in the bath additive of the present invention 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 moldability, and is preferably 50% by mass or less, more preferably 47% by mass or less, even more preferably 45% by mass or less, still more preferably 42% by mass or less, and even more preferably 40% by mass or less, from the viewpoints of storage stability, foaming properties, and solubility in bath water.

[0016] When component (A) contains an alkali metal sulfate (A2), the content of the alkali metal sulfate (A2) in the bath additive of the present invention is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, and even more preferably 9% by mass or more, from the viewpoint of improving moldability, and is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, from the viewpoint of storage stability and solubility in bath water.

[0017] From the viewpoint of improving moldability, component (A) is preferably an alkali metal bicarbonate (A1) and an alkali metal sulfate (A2). When component (A) is an alkali metal bicarbonate (A1) and an alkali metal sulfate (A2), the mass ratio of the content of the alkali metal bicarbonate (A1) to the content of the alkali metal sulfate (A2) [(A1) / (A2)] is, from the same viewpoints as above, preferably 0.5 or more, more preferably 0.6 or more, even more preferably 0.7 or more, still more preferably 1 or more, still more preferably 1.5 or more, still more preferably 2 or more, and preferably 10 or less, more preferably 9 or less, even more preferably 8 or less.

[0018] <Component (B): Dialkali metal carbonate> The bath additive of the present invention contains a dialkali metal carbonate as component (B) from the viewpoints of improving storage stability and effervescence. Component (B) may be one or more selected from the group consisting of sodium carbonate and potassium carbonate. From the viewpoints of improving moldability and storage stability, as well as foamability, solubility in bath water, and economy, it preferably contains sodium carbonate, and more preferably is sodium carbonate.

[0019] The content of component (B) in the bath additive of the present invention is 16% by mass or more from the viewpoint of improving storage stability and foaming properties, and from the viewpoint of solubility in bath water and moldability, it is preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0020] The mass ratio of the content of component (A) to the content of component (B) in the bath additive of the present invention [(A) / (B)] is 1.0 or more, preferably 1.1 or more, more preferably 1.4 or more, even more preferably 2 or more, and still more preferably 2.6 or more, from the viewpoint of improving moldability and storage stability, and is 5.4 or less, preferably 4 or less, more preferably 3.5 or less, and even more preferably 3 or less.

[0021] <Component (C): Organic acid> The bath additive of the present invention contains an organic acid as component (C). By including component (C), the bath additive of the present invention can be made into an effervescent solid bath additive that can generate carbon dioxide gas through the reaction with the alkali metal bicarbonate (A1) and component (B).

[0022] Examples of component (C) include carboxylic acid compounds, organic sulfonic acid compounds, and organic phosphoric acid compounds. From the viewpoints of improving moldability and storage stability, as well as foamability and solubility in bath water, carboxylic acid compounds are preferred. The carboxylic acid compound may be a compound having at least one carboxy group, but from the viewpoint of imparting foaming properties, a polycarboxylic acid having two or more carboxy groups is preferred. Examples of the carboxylic acid compound include aliphatic carboxylic acids, aromatic carboxylic acids, and heterocyclic carboxylic acids. Examples of the aliphatic carboxylic acid include dicarboxylic acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, maleic acid, and fumaric acid; and hydroxycarboxylic acids such as malic acid, tartaric acid, and citric acid. Examples of aromatic carboxylic acids include phthalic acid, benzoic acid, and salicylic acid. Examples of heterocyclic carboxylic acids include pyrrolidone carboxylic acid. One or more types of component (C) can be used. Among these, from the viewpoints of improving moldability and storage stability, foamability and solubility in bath water, and economy, component (C) is preferably an aliphatic carboxylic acid, more preferably a dicarboxylic acid, even more preferably one or more selected from the group consisting of fumaric acid, succinic acid, and adipic acid, even more preferably one or more selected from the group consisting of fumaric acid and succinic acid, and still more preferably fumaric acid.

[0023] The content of component (C) in the bath additive of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of foaming ability, and is preferably 55% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less, and even more preferably 42% by mass or less, from the viewpoint of improving moldability and storage stability.

[0024] When component (A) contains an alkali metal bicarbonate (A1), the mass ratio of the total content of components (A1) and (B) to the content of component (C) [{(A1) + (B)} / (C)] is, from the viewpoints of improving moldability and storage stability, preferably 0.3 or more, more preferably 0.5 or less, even more preferably 0.8 or more, still more preferably 1 or more, and still more preferably 1.8 or more, and from the viewpoints of foamability and solubility in bath water, is preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, and still more preferably 2 or less.

[0025] <Liquid oily component with a molecular weight of 300 or less> In the present invention, from the viewpoint of achieving a balanced improvement in moldability and storage stability, and from the viewpoint of easily obtaining a natural bathing sensation similar to that of plain water, the content of liquid oily components with a molecular weight of 300 or less in the bath additive is 0.1 mass% or less. In the present invention, the definitions of "liquid" and "oily component" are as described above. Examples of liquid oily components having a molecular weight of 300 or less include liquid oily components having a molecular weight of 300 or less, such as fragrances, hydrocarbon oils, ester oils, higher alcohols, higher fatty acids, and silicone oils. The liquid oily component having a molecular weight of 300 or less may be one type or a combination of two or more types.

[0026] Examples of fragrances include those described in "Synthetic Fragrances: Chemistry and Product Knowledge" (by Genichi Indo, published by The Chemical Daily in 2005, expanded and revised edition). Specifically, examples include synthetic fragrances such as hydrocarbon fragrances such as terpene hydrocarbons and sesquiterpene hydrocarbons, alcohol fragrances, aldehyde fragrances, ketone fragrances, ether fragrances, oxide fragrances, ester fragrances, and lactone fragrances, natural essential oils containing large amounts of these, and liquid oily components with a molecular weight of 300 or less in blended fragrances blended to match the desired scent. For example, liquid oily components of hydrocarbon fragrances having a molecular weight of 300 or less include myrcene, ocimene, terpinolene, alpha-terpinene, alpha-phellandrene, para-cymene, farnesene, cedrene, longifolene, copaene, guaiene, patcholene, gurjunene, limonene, citral, and terpinene.

[0027] Examples of hydrocarbon oils include liquid oily components with a molecular weight of 300 or less, such as paraffin and pristane. Among ester oils, liquid oily components having a molecular weight of 300 or less include fatty acid esters such as fatty acid monoesters composed of fatty acids and monohydric alcohols, fatty acid esters composed of fatty acids and polyhydric alcohols, and dicarboxylic acid diesters composed of dicarboxylic acids and monohydric alcohols. Among higher alcohols, liquid oily components having a molecular weight of 300 or less include higher alcohols having 12 to 20 carbon atoms, such as hexyldecanol, hexadecanol, isomyristyl alcohol, isopalmityl alcohol, isostearyl alcohol, stearyl alcohol, oleyl alcohol, and octyldodecanol. Among higher fatty acids, examples of liquid oily components having a molecular weight of 300 or less include isostearic acid and oleic acid. Among silicone oils, liquid oily components having a molecular weight of 300 or less include linear organopolysiloxanes, branched organopolysiloxanes, and cyclic organopolysiloxanes.

[0028] The content of liquid oily components with a molecular weight of 300 or less in the bath additive of the present invention is 0.1% by mass or less, preferably 0.07% by mass or less, more preferably 0.05% by mass or less, and even more preferably 0.03% by mass or less, from the viewpoint of improving moldability and storage stability in a balanced manner; from the viewpoint of obtaining a natural bathing sensation similar to that of plain water, it is even more preferably 0.01% by mass or less, even more preferably 0.005% by mass or less, and even more preferably essentially 0% by mass, i.e., it contains substantially no liquid oily components with a molecular weight of 300 or less. When two or more liquid oily components having a molecular weight of 300 or less are contained in the bath additive of the present invention, the content of the liquid oily component having a molecular weight of 300 or less is the total content of these components.

[0029] The bath additive of the present invention may also contain a liquid oily component having a molecular weight of more than 300, provided that the effects of the present invention are not impaired. From the viewpoints of maintaining good moldability and storage stability, and of solubility in bath water, the content of the liquid oily component having a molecular weight of more than 300 is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and even more preferably substantially 0% by mass.

[0030] <Nonionic surfactants> The bath additive of the present invention may further contain a nonionic surfactant from the viewpoint of improving the solubility and formability of the bath additive in bath water. Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyglyceryl alkyl ethers, alkyl glucosides, polyoxyethylene alkylamines, polyoxyethylene alkenyl ethers, sucrose fatty acid esters, polyoxyethylene fatty acid esters, fatty acid polyglyceryl esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene hydrogenated castor oil, and one or more of these can be used.

[0031] Among nonionic surfactants, the alkyl groups in polyoxyethylene alkyl ethers, polyglyceryl alkyl ethers, alkyl glucosides, and polyoxyethylene alkylamines, the alkenyl groups in polyoxyethylene alkenyl ethers, and the fatty acids in sucrose fatty acid esters, polyoxyethylene fatty acid esters, fatty acid polyglyceryls, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters preferably have 8 to 22 carbon atoms, more preferably 10 to 22 carbon atoms, even more preferably 12 to 20 carbon atoms, and still more preferably 14 to 20 carbon atoms, from the viewpoint of improving the solubility and moldability of the bath additive in bath water.

[0032] Among nonionic surfactants, the average number of moles of ethylene oxide added (hereinafter referred to as "average number of moles of EO added") in polyoxyethylene alkyl ethers, polyoxyethylene alkenyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbit fatty acid esters, and polyoxyethylene hydrogenated castor oil is, from the viewpoint of improving the solubility and moldability of the bath additive in bath water, 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. Note that the average number of moles of EO added is a number average value.

[0033] Among nonionic surfactants, from the viewpoint of improving the solubility and moldability of the bath additive in bath water, one or more selected from the group consisting of polyoxyethylene alkyl ethers, sucrose fatty acid esters, polyoxyethylene fatty acid esters, and polyoxyethylene hydrogenated castor oil are preferred. The alkyl group or fatty acid of these nonionic surfactants preferably has from 8 to 22 carbon atoms, more preferably from 10 to 22 carbon atoms, even more preferably from 12 to 20 carbon atoms, and still more preferably from 14 to 20 carbon atoms.

[0034] When the bath additive of the present invention contains a nonionic surfactant, the content of the nonionic surfactant in the bath additive of the present invention is preferably 0.005% by mass or more, more preferably 0.007% by mass or more, and even more preferably 0.01% by mass or more, from the viewpoint of improving the solubility and moldability of the bath additive in bath water, and is preferably 0.1% by mass or less, more preferably 0.07% by mass or less, even more preferably 0.05% by mass or less, still more preferably 0.03% by mass or less, and even more preferably 0.02% by mass or less, from the viewpoint of obtaining a natural bathing sensation similar to that of plain water.

[0035] The bath additive of the present invention may also contain at least one surfactant other than nonionic surfactants, i.e., at least one selected from the group consisting of anionic surfactants, cationic surfactants, and amphoteric surfactants, to the extent that the effects of the present invention are not impaired. From the viewpoints of maintaining good moldability and storage stability, and of solubility in bath water, the total content of these other surfactants in the bath additive of the present invention is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and even more preferably substantially 0% by mass.

[0036] <Water-soluble polymer> The bath additive of the present invention may further contain a water-soluble polymer from the viewpoint of improving the solubility and formability of the bath additive in bath water. Examples of the water-soluble polymer include synthetic water-soluble polymers, natural synthetic water-soluble polymers, and semi-synthetic water-soluble polymers. Examples of synthetic water-soluble polymers include polyethylene glycol, polyvinylpyrrolidone, sodium polyacrylate, polyethyleneimine, and polyvinyl alcohol. Examples of natural water-soluble polymers include glue, gelatin, collagen protein, casein, sodium alginate, carrageenan, furcellaran, tamarind gum, pectin, gum arabic, guar gum, xanthan gum, tragacanth gum, locust bean gum, dextrin, dextran, agar, and starch. Examples of semi-synthetic water-soluble polymers include carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose acetate phthalate, propylene glycol alginate, oxidized starch, esterified starch, etherified starch, and cationic starch. These water-soluble polymers can be used alone or in combination of two or more. Among these, the water-soluble polymer is preferably one or more selected from the group consisting of polyethylene glycol and dextrin, more preferably polyethylene glycol, from the viewpoint of the solubility of the bath additive in bath water and moldability. The molecular weight of the polyethylene glycol is preferably 4,000 or more and 10,000 or less, and more preferably 5,000 or more and 9,000 or less.

[0037] When the bath additive of the present invention contains a water-soluble polymer, the content of the water-soluble polymer in the bath additive of the present invention is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, from the viewpoint of improving the solubility and formability of the bath additive in bath water. Furthermore, from the viewpoint of ensuring the amount of carbon dioxide gas generated and improving foaming properties, the content is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less.

[0038] Furthermore, the bath additive of the present invention may further contain magnesium sulfate or a hydrate thereof from the viewpoint of improving the warming effect during bathing and from the viewpoint of improving the moldability and storage stability of the bath additive. When the bath additive of the present invention contains magnesium sulfate or a hydrate thereof, the total content of magnesium sulfate and its hydrate in the solid bath additive of the present invention is preferably 0.03% by mass or more and 12.5% ​​by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, even more preferably 1% by mass or more and 8% by mass or less, and even more preferably 2% by mass or more and 5% by mass or less, from the viewpoint of improving the warming effect during bathing and from the viewpoint of improving the moldability and storage stability of the bath additive.

[0039] <Other ingredients> The bath additive of the present invention may contain other ingredients that are normally used in bath additives, such as inorganic salts other than those listed above, excipients such as calcium silicate and glucose, opacifiers such as titanium oxide, disintegrants, medicinal ingredients such as herbal medicines, and pigments.

[0040] (Dosage form) The dosage form (product form) of the bath additive of the present invention when used is preferably a tablet. Tablets include compressed tablets and briquettes, and compressed tablets are more preferred from the viewpoint of moldability. When the bath additive of the present invention is in the form of a tablet or briquette, it can be produced by a conventional method such as compression molding using a press tableting machine or a briquetting machine. In the manufacture of tableting or briquetting agents, for example, all of the components constituting the bath additive of the present invention may be dry-blended to obtain a powder, which may then be subjected to compression molding, or a portion of the components may be granulated or molded in advance, and then mixed with the remaining components to obtain a mixture, which may then be subjected to compression molding. [Example]

[0041] The present invention will be described below with reference to examples, but the present invention is not limited to the scope of the examples.

[0042] Examples 1 to 13 and Comparative Examples 1 to 5 (Production and Evaluation of Foaming Solid Bath Additives) The powder obtained by mixing the ingredients shown in Tables 1 and 2 was used to produce tablets (compressed tablets) of 40 g mass and 15.0-15.2 mm height using a rotary tablet press at a tableting speed of 20 tablets / min. The tablets were placed in a bag made of aluminum foil laminated with a polymer film and heat-sealed. Furthermore, the formability, storage stability, and natural bathing sensation, similar to plain water, were evaluated using the methods described below. The results are shown in Tables 1 and 2. The blending amounts (mass %) of each component shown in Tables 1 and 2 are all active amounts.

[0043] <Moldability> Using the powder obtained by mixing the ingredients shown in the table, 100 tablets were continuously compressed in a rotary tablet press at a tableting speed of 20 tablets / min with a mass of 40 g and a tablet height of 15.0 to 15.2 mm. The presence or absence of sticking and the surface condition of the tablets were visually observed and evaluated on a 4-point scale according to the following criteria: A rating of 4 to 2 was considered pass, and a rating of 1 was considered fail. 4: There is very little adhesion to the die of the tablet press, and the surface of the resulting tablets is smooth. 3: There is little adhesion to the die of the tablet press, and the surface of the resulting tablets is smooth. 2: There was a fair amount of adhesion to the die of the tablet press, and slight irregularities were observed on the surface of the obtained tablets, but this was within the level for practical use. 1: There is a great deal of adhesion to the die of the tablet press, and unevenness is observed on the surface of the resulting tablets.

[0044] <Storage stability> Film-packaged samples of each solid bath additive from the Examples and Comparative Examples were stored in a 50°C thermostatic chamber for two weeks, and the presence or absence of swelling in the packaging after storage was observed. The samples were evaluated on a three-point scale according to the following criteria, with a rating of 3 to 2 being considered a pass and a rating of 1 being considered a fail. 3: No swelling observed 2: Slight swelling is observed, but it is at a level suitable for actual use. 1: Swelling is observed

[0045] <Natural bathing sensation like fresh water> 40 g of each solid bath additive of the Examples was added to 150 L of bath water at 40°C, and four expert panelists each bathed for 10 minutes. After the generation of carbon dioxide gas was completed, the remaining bubbles on the surface of the bath water when stirred were visually confirmed and the presence or absence of odor was evaluated according to the following criteria, and the average value was rounded off to the nearest whole number to obtain the evaluation value. A higher evaluation value indicates less remaining bubbles and odor on the surface of the bath water, and a better result is obtained, providing a natural bathing experience like plain water. Note that the solid bath additive of the Comparative Example failed the evaluation results for either moldability or storage stability, so the bathing experience was not evaluated. 3: No residual foam or odor is observed, and the bath feels natural, like plain water. 2: At least one of residual foam and odor is slightly noticeable, but the bathing sensation is somewhat similar to that of plain water. 1: At least one of residual bubbles and odor is observed, and the bathing sensation is not close to that of plain water.

[0046] [Table 1]

[0047] [Table 2]

[0048] From Table 1, it can be seen that the effervescent solid bath additive of this example is excellent in both moldability and storage stability. In contrast, the effervescent solid bath additive of this comparative example shown in Table 2 was inferior in either moldability or storage stability. [Industrial Applicability]

[0049] According to the present invention, it is possible to provide a foamable solid bath additive that has excellent moldability and storage stability.

Claims

1. The following components (A) to (D): (A) Alkali metal bicarbonate (A1) and alkali metal sulfate (A2) (B) Dialkali metal carbonate (C) Organic acid (D) Nonionic surfactant A foaming solid bath additive comprising: The content of component (B) in the bath additive is 16% by mass or more, the mass ratio [(A) / (B)] of the content of component (A) to the content of component (B) in the bath additive is 1.0 or more and 5.4 or less; the mass ratio [(A1) / (A2)] of the content of component (A1) to the content of component (A2) in the bath additive is 0.5 or more and 10 or less; The content of component (D) in the bath additive is 0.05% by mass or less, The effervescent tableted solid bath additive has a liquid oily component with a molecular weight of 300 or less in a content of 0.1% by mass or less.

2. 2. The effervescent tableted solid bath additive according to claim 1, wherein the content of component (A) is 30% by mass or more.

3. An effervescent tableted solid bath additive as described in claim 1 or 2, wherein the content of component (D) is 0.01 mass% or more and 0.05 mass% or less.

4. 4. The effervescent tablet solid bath additive according to claim 1, wherein the mass ratio [{(A1) + (B)} / (C)] of the total content of component (A1) and component (B) to the content of component (C) is 0.8 or more and 5 or less.

5. 5. The effervescent tableted solid bath additive according to claim 1, wherein component (C) is at least one selected from the group consisting of fumaric acid and succinic acid.

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