Water system components

Abstract

To provide an aqueous composition for impregnating a cleaning sheet which has excellent storage stability and reduces skin irritation.SOLUTION: There is provided an aqueous composition for impregnating a cleaning sheet in which a preservability improver and a solubilizer are contained in purified water and which comprises 0.030 to 0.050 mass% of benzalkonium chloride as a preservability improver, 0.025 to 0.070 mass% of polyaminopropylbiguanide hydrochloride and 0.003 to 0.050 mass% of glyceryl caprylate and comprises a solvent for solubilizing glyceryl caprylate as a solubilizer, wherein purified water concentration in the aqueous composition is 99.85 to 99.92 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aqueous composition for impregnating cleaning sheets, comprising a preservative and a solubilizer. [Background technology]

[0002] Traditionally, wet-type cleansing wipes have been used to facilitate the wiping away of dirt when changing disposable diapers for infants and those receiving care, or to wipe away dirt from hands and bodies. Wet-type cleansing wipes are usually made by impregnating a base sheet with an aqueous composition containing an antibacterial agent in purified water.

[0003] The aforementioned aqueous composition should ideally contain a low amount of antibacterial agents and other substances in the purified water to reduce skin irritation. In particular, for cleansing sheets used for infants and elderly people with sensitive skin, it is desirable that the aqueous composition impregnates the sheets with the lowest possible amount of irritating ingredients and a high concentration of purified water. On the other hand, cleansing sheets impregnated with an aqueous composition with a high concentration of purified water may develop bacteria and mold as the storage period lengthens, potentially reducing their storage stability.

[0004] Patent documents 1 to 3 below disclose aqueous solutions containing antibacterial agents and the like. Patent Document 1, described below, states that parabens (parahydroxybenzoic acid esters), which have been widely used as antibacterial and preservative agents in cosmetics and the like, require the addition of solubilizers such as surfactants, but that the antibacterial and preservative power of parabens is significantly reduced when solubilizers are added. Therefore, Patent Document 1 discloses a topical skin preparation that does not contain parabens, in which component (A) is 0.2% by mass or more of 2,2-bis(hydroxymethyl)propionic acid n-hexyl, and component (B) is at least twice the amount of C6-C8 alkyl glyceryl ether and / or C8-C12 fatty acid glyceryl ester. Caprylic acid glyceryl is given as an example of the fatty acid glyceryl ester.

[0005] Patent Document 2 below discloses a foaming antimicrobial skin detergent as a personal care composition, which does not contain triclosan, which is of environmental sustainability and health concern, and includes a cationic active ingredient, a cationic compatible surfactant, a foam promoter, a foam structure strengthening agent, and a skin modifier that reduces irritation to mammalian skin tissue. Glyceryl caprate is given as the foam promoter. Patent Document 3 below discloses a preservative for hand towels or wet tissues that contains glycerin fatty acid esters and quaternary ammonium salts.

[0006] Patent documents 4 to 6 below disclose cleaning sheets impregnated with aqueous solutions. Patent document 4 below discloses a cleaning sheet for wiping the bottom of infants, in which a cleaning agent is impregnated into a nonwoven fabric sheet. The concentration of purified water in the cleaning agent is in the range of 99.80 to 99.90% by weight, and the cleaning agent contains benzalkonium chloride, iodide propynyl butylcarbamate, and propylene glycol or 1,3-butylene glycol as antibacterial and preservative agents. It is also stated that such cleaning sheets can suppress skin irritation.

[0007] Patent Document 5 discloses a water-soluble composition for impregnating fiber sheets, comprising a mixture of polyaminopropyl biguanide and a quaternary ammonium salt, sodium benzoate, citric acid, disodium ethylenediaminetetraacetate, and a nonionic surfactant, and having a pH of 3.5 to 4.5, and a fiber sheet impregnated with the water-soluble composition. Patent Document 6 discloses a wet sheet in which a base sheet is impregnated with a liquid containing lactic acid, citric acid or salts thereof, a quaternary ammonium salt type surfactant, and water, but without ethanol, and having a pH of 3.0 or higher and less than 6.0 at 25°C. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 4927986 [Patent Document 2] Patent No. 6431180 [Patent Document 3] Japanese Patent Publication No. 2021-003399 [Patent Document 4] Patent No. 5876981 [Patent Document 5] Patent No. 5845098 [Patent Document 6] Japanese Patent Publication No. 2020-199090 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The topical skin preparations disclosed in Patent Document 1 are formulated to exert antibacterial and preservative effects in solutions with high concentrations of additive components, such as creams, lotions, and emulsions. Therefore, it is necessary to include a relatively large amount of antibacterial and preservative agents in the topical skin preparations. In the foaming antibacterial skin detergent disclosed in Patent Document 2, glyceryl caprate is included as a foam enhancer, along with foam structure strengthening agents such as polyethylene glycol (PEG) 8000, to provide sufficient foam volume and a high-density, stable foam structure during washing. Furthermore, in the formulation example, the skin detergent contains a large amount of additive components other than pure water, approximately 15-20% by weight.

[0010] The examples in Patent Document 3 suggest that the antibacterial effect is insufficient when the preservative component is only glyceryl caprate, so it is assumed that the antibacterial agent in the disclosed preservative is mainly a quaternary ammonium salt such as benzalkonium chloride. However, if the antibacterial agent is only benzalkonium chloride, the antibacterial effect decreases in the weakly acidic pH range, and if the antibacterial agent is substantially a single component, there is a risk that it will not be able to exert a sufficient antibacterial effect due to the presence of bacterial species resistant to the antibacterial agent. In the cleaning sheet disclosed in Patent Document 4, propynyl iodide butylcarbamate is contained as a bactericidal preservative in the impregnated cleaning agent, but a cleaning sheet that does not contain this component is desired. Furthermore, improved antifungal properties are also desired in the cleaning sheet.

[0011] The water-soluble composition for impregnating fiber sheets disclosed in Patent Document 5 contains sodium benzoate as a bactericidal preservative. Since sodium benzoate effectively exhibits antibacterial properties in a weakly acidic range, several pH adjusters are added to adjust the pH of the water-soluble composition. Furthermore, nonionic surfactants are added to reduce skin irritation, resulting in a large number of additive components. The liquid formulation for impregnating wet sheets disclosed in Patent Document 6 describes an example of formulation with lactic acid, citric acid, etc., in amounts of 3 to 10 times the weight of a quaternary ammonium salt type surfactant. Consequently, the concentration of purified water in the liquid formulation becomes relatively low, and the document states that a purified water concentration of 97.0 to 99.7% by mass is preferable. In addition, the formulation of lactic acid, quaternary ammonium salt type surfactant, etc., as disinfectants is described in the document, and its antibacterial properties are evaluated, but its antifungal properties are not described.

[0012] When multiple preservatives are added to improve both the antibacterial and antifungal properties of the aqueous composition impregnated into the cleaning sheets, it generally becomes difficult to maintain a high concentration of purified water. Furthermore, to reduce the skin irritation of the cleaning sheets, it is desirable to maintain a high concentration of purified water and adjust the pH to a weakly acidic range. However, in this case, the addition of a pH adjuster is generally necessary, and there is a problem that the antibacterial properties decrease depending on the type of antibacterial agent at a weakly acidic pH.

[0013] The present invention has been made in view of these circumstances, and aims to provide an aqueous composition for impregnating a base sheet that improves antibacterial and antifungal properties by incorporating a specific preservative stabilizer into the aqueous composition to impregnate the base sheet, while also maintaining a high concentration of purified water and maintaining a slightly acidic pH, making it suitable for use on infants with delicate skin and elderly people with sensitive skin. [Means for solving the problem]

[0014] In view of the above-mentioned prior art, the present inventors have found that, in order to improve the shelf life of an aqueous composition for impregnating a cleaning sheet, they have combined benzalkonium chloride, which may be affected by pH, and polyaminopropyl biguanide hydrochloride, which is less affected by pH, as antibacterial agents, and have also included glyceryl caprate as an antifungal agent, and a solubilizer based on the formulation of glyceryl caprate, and further, in order to suppress skin irritation, they have maintained a high concentration of purified water in the aqueous composition and have included predetermined amounts of benzalkonium chloride and polyaminopropyl biguanide hydrochloride, respectively, to keep the pH of the aqueous composition in the weakly acidic range, thereby obtaining an aqueous composition for impregnating a cleaning sheet that has excellent storage stability and further reduces skin irritation, and have completed the present invention. In other words, the gist of the present invention is the invention described in (1) to (7) below.

[0015] (1) A water-based composition for impregnating a cleaning sheet, comprising purified water, benzalkonium chloride and polyaminopropyl biguanide hydrochloride as antimicrobial agents, glyceryl caprate as an antifungal agent, and a solvent that solubilizes glyceryl caprate as a solubilizer, An aqueous composition characterized in that the content of benzalkonium chloride is 0.030% by mass or more and 0.050% by mass or less, the content of polyaminopropyl biguanide hydrochloride is 0.025% by mass or more and 0.070% by mass or less, and the content of glyceryl caprate is 0.003% by mass or more and 0.050% by mass or less, and the concentration of purified water in the aqueous composition is 99.85% by mass or more and 99.92% by mass or less.

[0016] (2) The total content of benzalkonium chloride and polyaminopropyl biguanide hydrochloride in the aqueous composition (B1 + B2) is 0.060 or more and 0.105% by mass or less. The aqueous composition according to (1) above, wherein the mass ratio (B2 / B1) of the content of benzalkonium chloride and polyaminopropyl biguanide hydrochloride is 0.625 or more and 2.00 or less. (3) The mass ratio (C1 / (B1 + B2)) of the content of glyceryl caprate, which is a mold inhibitor component, to the total content (B1 + B2) of benzalkonium chloride and polyaminopropyl biguanide hydrochloride, which are antibacterial agent components, in the aqueous composition is 0.035 or more and 0.833 or less, and the aqueous composition according to (1) or (2) above.

[0017] (4) The mass ratio (D1 / C1) of the content of the solvent to the content of glyceryl caprate, which is a mold inhibitor component, in the aqueous composition is 0.60 or more and 2.14 or less. The aqueous composition according to any one of (1) to (3) above. (5) The pH of the aqueous composition at 25°C is 3.47 or more and 3.83 or less. The aqueous composition according to any one of (1) to (4) above.

[0018] (6) The solvent for solubilizing glyceryl caprate is liquid at 15 to 25°C at normal temperature and is a polyether having an OH terminal group. The aqueous composition according to any one of (1) to (5) above. (7) The solvent for solubilizing glyceryl caprate is polyethylene glycol having a number average molecular weight of 100 or more and 600 or less. The aqueous composition according to any one of (1) to (6) above.

Advantages of the Invention

[0019] The aqueous composition of the present invention contains a preservative improver and a solubilizing agent in purified water. As the preservative improver, benzalkonium chloride and polyaminopropyl biguanide hydrochloride, which are antibacterial agent components, and glyceryl caprate, which is a mold inhibitor component, are each contained in a specific amount. Therefore, antibacterial and antifungal properties are exhibited, and the storage stability of the aqueous composition is enhanced. Furthermore, in the aqueous composition of the present invention, by minimizing the content of preservatives and solubilizers and increasing the concentration of purified water, and by including predetermined amounts of benzalkonium chloride and polyaminopropyl biguanide hydrochloride, the pH of the aqueous composition is maintained in the weakly acidic range, thereby reducing skin irritation when the cleaning sheet impregnated with the aqueous composition is used. [Modes for carrying out the invention]

[0020] The aqueous composition of the present invention and the cleaning sheet in which the aqueous composition is impregnated will be described below. 1.Aqueous composition The present invention provides an aqueous composition for impregnating cleaning sheets, comprising purified water containing, as preservatives, benzalkonium chloride and polyaminopropyl biguanide hydrochloride, which are antimicrobial agents, and glyceryl caprate, which is an antifungal agent, and as a solubilizer, a solvent that solubilizes glyceryl caprate. The aqueous composition is characterized in that it contains 0.030% by mass or more and 0.050% by mass or less of benzalkonium chloride, 0.025% by mass or more and 0.070% by mass or less of polyaminopropyl biguanide hydrochloride, and 0.003% by mass or more and 0.050% by mass or less of glyceryl caprate, and the concentration of purified water in the aqueous composition is 99.85% by mass or more and 99.92% by mass or less. The following describes (1) purified water, (2) preservatives, (3) solubilizers, (4) the concentration of purified water and pH value in the aqueous composition, and (5) other components that can be added to the aqueous composition.

[0021] (1) Purified water The purified water used in the aqueous composition of the present invention can be obtained, for example, by using tap water or other ordinary water, pre-treating it as necessary, and then removing impurities by means of ion exchange, distillation, filtration, etc. Furthermore, the seventeenth edition of the Japanese Pharmacopoeia defines purified water as "prepared from ordinary water by a system of ion exchange, distillation, reverse osmosis, or ultrafiltration, either alone or in combination," and thus shares commonalities with the processing method of the above aqueous composition.

[0022] The purified water used in the aqueous composition of the present invention is preferably ordinary water such as tap water from which impurities have been removed by the above means, and then further sterilized using an ultraviolet sterilization device or the like. This sterilization treatment can be performed either before or after the purification of the water, but it is preferred to perform it after the purification of the water.

[0023] Examples of the aforementioned sterilization treatments include ultraviolet sterilization, thermal sterilization, ozone water sterilization, and chlorine-based sterilization, but ultraviolet sterilization is preferred as it does not require large equipment or a large amount of heat and does not affect water quality. The purified water obtained by the above means preferably has an electrical conductivity of 1 μS / cm or less at 25°C after purification, or after purification and sterilization treatment. Electrical conductivity indicates how easily electricity is conducted in an aqueous solution, and is the reciprocal of the electrical resistance of the solution. Electrical conductivity increases as the content of ionic impurities increases.

[0024] (2) Preservatives When using an aqueous composition for wiping the bottom of infants or for impregnating cleansing sheets for sick people, the elderly, or infants, a higher concentration of purified water in the aqueous composition is preferable to minimize skin irritation. On the other hand, aqueous compositions with a higher concentration of purified water are more susceptible to bacterial and mold growth during storage, leading to storage problems. Therefore, in order to minimize skin irritation by keeping the concentration of preservatives in the aqueous composition as low as possible and to enable long-term storage, the selection of preservatives and the determination of their content are extremely important.

[0025] Various antibacterial agents are known as preservatives, but there is a tendency to avoid the use of parabens, which have been widely used until now. Therefore, in the present invention, benzalkonium chloride and polyaminopropyl biguanide hydrochloride, which are antibacterial components, and glyceryl caprate, which is an antifungal component, are used as preservatives, all of which are used in cosmetics. In the present invention, "antibacterial component" means a component that mainly exhibits antibacterial properties, and "antifungal component" means a component that mainly exhibits antifungal properties.

[0026] As an antibacterial agent, benzalkonium chloride is listed in the list of preservatives that can be used in cosmetics (positive list), but it is desirable to reduce its content. On the other hand, if the antibacterial agent component consists only of benzalkonium chloride, the antibacterial activity may decrease in the weakly acidic pH range, and the antibacterial effect may not be fully exerted due to the presence of bacterial species resistant to the antibacterial agent. Therefore, it is preferable to use at least two components as antibacterial agents, and in the aqueous composition of the present invention, benzalkonium chloride and polyaminopropyl biguanide hydrochloride are used in combination as antibacterial agents. This combination improves antibacterial activity, and by adjusting the content ratio of benzalkonium chloride and polyaminopropyl biguanide hydrochloride, it is also possible to adjust the pH of the aqueous composition to a weakly acidic pH that is less irritating to the skin.

[0027] If only benzalkonium chloride and polyaminopropyl biguanide hydrochloride, which are antibacterial components, are selected as preservatives, the antifungal properties may be insufficient. Therefore, by using glyceryl caprate, which is an antifungal component, in combination, it is possible to improve both antibacterial and antifungal properties. When glyceryl caprate is included in an aqueous composition, it is necessary to include a solvent that solubilizes glyceryl caprate as a solubilizer, since this component has low solubility in aqueous solutions.

[0028] By using benzalkonium chloride and polyaminopropyl biguanide hydrochloride in combination as antibacterial agents, it is possible to reduce the amount of benzalkonium chloride. Thus, by including small amounts of benzalkonium chloride and polyaminopropyl biguanide hydrochloride in the aqueous composition to improve its antibacterial properties, and further including small amounts of glyceryl caprate to improve its antifungal properties, it is possible to improve storage stability and adjust the pH of the aqueous composition to weakly acidic, thereby obtaining an aqueous composition that is less irritating to human skin. This is a characteristic feature of the present invention. The following describes the preservatives contained in the aqueous composition of the present invention: benzalkonium chloride, polyaminopropyl biguanide hydrochloride, and glyceryl caprate.

[0029] (2-1) Each component in the preservative enhancer (i) Benzalkonium chloride Benzalkonium chloride, which is widely used as an antibacterial agent in the cosmetics field and other areas, has the chemical name alkyldimethylbenzylammonium chloride and is represented by the following chemical formula (1). [RC6H5CH2N + (CH3)2]Cl - ··········(1) The benzalkonium chloride represented by the above chemical formula (1) has some or all of the alkyl group (R) having 8 to 18 carbon atoms (C8H 17 ~C 18 H 37 It is a mixture consisting of alkyl groups.

[0030] Benzalkonium chloride, when diluted in an aqueous solution, is weakly alkaline and exhibits excellent bactericidal properties in a weakly alkaline environment. However, it is known that its bactericidal properties decrease when the pH is adjusted to a neutral or weakly acidic aqueous solution. For example, when using the carbolic coefficient (a numerical value indicating how many times more bactericidal a substance is compared to carbolic acid) to show the relationship between pH and bactericidal properties for commercially available benzalkonium chloride, it is known that at around room temperature, the bactericidal properties at pH 7 decrease to approximately 0.86 and 0.54 times those at pH 9 and 11, respectively, and the bactericidal properties at pH 5 decrease to approximately 0.78 and 0.49 times those at pH 9 and 11, respectively.

[0031] (ii) Polyaminopropyl biguanide hydrochloride Polyaminopropyl biguanide is a cationic polymer with numerous positive charges in its molecule, represented by the following chemical formula (2). [-NH-C(=NH)-NH-C(=NH)-NH-(CH2)3-] n (2) Polyaminopropyl biguanide is known to exist in the form of inorganic salts such as hydrochloride and organic salts such as fumarate. When used as an antibacterial agent, it can be used as polyaminopropyl biguanide or an inorganic salt of polyaminopropyl biguanide, but in the aqueous composition of the present invention, polyaminopropyl biguanide hydrochloride is preferred.

[0032] Polyaminopropyl biguanide hydrochloride has high solubility in water, stable antibacterial activity over a wide temperature and pH range, and exhibits antibacterial activity against bacteria such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Therefore, it has a broad antibacterial spectrum against bacteria, but it is known to have relatively low antibacterial effect against fungi such as Candida and Aspergillus niger. In the above chemical formula (2), the degree of polymerization n of polyaminopropyl biguanide is preferably 5 to 50, and more preferably 10 to 20. Furthermore, the weight-average molecular weight of polyaminopropyl biguanide is preferably 800 to 8000, and more preferably 2000 to 3000. The weight-average molecular weight can be measured by known methods.

[0033] (iii) Glyceryl caprate Glyceryl caprate is a monoester of capric acid, a saturated fatty acid with 10 carbon atoms, and glycerol, and exists as two isomers, represented by the following chemical formulas (3) and (4). CH2OH-CHOH-CH2-O-CO-(CH2)8CH3···(3) CH2OH-CH-O-(CO-(CH2)8CH3)-CH2OH ···(4) Monoesters of fatty acids with 8, 10, and 12 carbon atoms and glycerin are known. Among these, glyceryl caprate, which is a monoester of capric acid with 10 carbon atoms and glycerin, is preferred as an antifungal agent, considering the synergistic effect of antibacterial and antifungal properties when used in combination with other antibacterial agents, solubility in aqueous solutions using solubilizers, antifungal effect at low concentrations, and ease of availability.

[0034] Glyceryl caprate is a nonionic surfactant generally synthesized by esterifying naturally derived vegetable oil fatty acids, such as soybean oil, with glycerin. Glyceryl caprate is solid at room temperature and is lipophilic, so its solubility in aqueous solutions is 126 mg / liter at 25°C. While glyceryl caprate has primarily been used in oily and emulsified cosmetics, it can also be incorporated into water-based products when used in combination with a solubilizer.

[0035] (2-2) Content of each component of the preservative enhancer In order to improve the storage stability of the cleansing sheets and reduce skin irritation, the blending range of each component of the preservation-improving agent in the aqueous composition of the present invention impregnated into the cleansing sheets must be as follows.

[0036] The content of benzalkonium chloride, an antibacterial agent component, is 0.030% by mass or more and 0.050% by mass or less, preferably 0.035% by mass or more and 0.050% by mass or less. The content of polyaminopropyl biguanide hydrochloride, an antibacterial agent component, is 0.025% by mass or more and 0.070% by mass or less, preferably 0.035% by mass or more and 0.070% by mass or less. The content of glyceryl caprate, an antifungal agent component, is 0.003% by mass or more and 0.050% by mass or less, preferably 0.0035% by mass or more and 0.050% by mass or less. In the aqueous composition of the present invention, benzalkonium chloride, polyaminopropyl biguanide hydrochloride, and glyceryl caprate can effectively exhibit antibacterial and antifungal properties, respectively, at the above-mentioned concentrations.

[0037] (2-3) Content ratio of each component of the preservative enhancer To further consider the storage stability and reduction of skin irritation of the cleansing sheets, it is preferable that the content ratio of each component of the preservation-improving agent in the aqueous composition of the present invention impregnated into the cleansing sheets be as follows. Considering antibacterial properties, the total amount of benzalkonium chloride (b1) and polyaminopropyl biguanide hydrochloride (b2) (b1+b2) is preferably 0.06% by mass or more and 0.105% by mass or less. Considering the pH of the aqueous composition to reduce skin irritation, the mass ratio of polyaminopropyl biguanide hydrochloride (b2) to benzalkonium chloride (b1) (b2 / b1) is preferably 0.625 or more and 2.00 or less.

[0038] Furthermore, considering the improvement of both the antibacterial and antifungal properties of the aqueous composition, the mass ratio (c1 / (b1+b2)) of the content of glyceryl caprate (c1), which is an antifungal agent component, to the total amount (b1+b2) of the content of benzalkonium chloride (b1) and polyaminopropyl biguanide hydrochloride (b2), which are antibacterial agents, is preferably 0.035 or more and 0.833 or less.

[0039] (3) Solubilizer As mentioned above, glyceryl caprate has extremely low solubility in aqueous solutions. Therefore, in order to uniformly dissolve glyceryl caprate in an aqueous composition, it is necessary to include a solvent that solubilizes glyceryl caprate. The solvent is not particularly limited as long as it can uniformly dissolve glyceryl caprate in the aqueous composition. However, considering solubility with glyceryl caprate, water solubility, content, and safety, a polyether that is liquid at room temperature (15-25°C) and has OH-terminal groups is preferred. Examples of such polyethers include polyethylene glycol obtained by the addition reaction of ethylene oxide, as well as polyethers obtained by the addition reaction of ethylene oxide with propylene oxide or 1,3-butylene oxide. Because these polyethers all have ether bonds and OH bonds at their ends, they are thermally stable in excellent solvents and relatively inert to many chemicals.

[0040] Among the polyethers mentioned above, polyethylene glycol with a number average molecular weight of 100 to 600 is more preferred, and polyethylene glycol with a number average molecular weight of 200 to 300 is even more preferred, considering its liquid state at room temperature, reduced irritation, and the solubilization of glyceryl caprate. Polyethylene glycol with a number average molecular weight of 100 to 600 has a low vapor pressure and can suppress stickiness when dissolved in an aqueous solution at a low concentration. Furthermore, in order to reduce skin irritation, it is preferable that the polyether does not contain lower alcohols such as methanol or ethanol. To maintain solubilization in aqueous compositions, prevent stickiness, and maintain a high concentration of purified water, the mass ratio (d1 / c1) of the solvent content (d1) to the capric acid content (c1) in the aqueous composition is preferably 0.60 or more and 2.14 or less.

[0041] (4) Purified water concentration and pH value in aqueous compositions In the aqueous composition of the present invention, the concentration of purified water is 99.85% by mass or more and 99.92% by mass or less. The aqueous composition contains a preservative enhancer and a solubilizer in the purified water, but as described above, by keeping the content of each in small amounts, it is possible to maintain a high concentration of purified water and reduce skin irritation.

[0042] Furthermore, considering the need to reduce skin irritation to infants, the elderly, and sick people with sensitive skin, and the fact that the pH of the skin surface is weakly acidic, as will be described later, the pH of the aqueous composition at 25°C is preferably 3.47 to 3.83. The pH value of the aqueous composition is a measurement obtained using a HORIBA pH METER F-21 manufactured by HORIBA, Ltd. When an aqueous composition with such a pH range is impregnated into a nonwoven fabric sheet obtained from, for example, a composite fiber made of polyethylene terephthalate fibers and rayon fibers, it becomes possible to maintain the pH of the aqueous phase in the resulting cleansing sheet at a weakly acidic level of approximately 6.1 to 6.6, thereby reducing skin irritation when wiping the body with the cleansing sheet.

[0043] (5) Other components that can be added to aqueous compositions In the aqueous composition of the present invention, small amounts of other components besides preservatives and solubilizers may be added, as long as they do not impair the effects of the present invention. Examples of such components include hyaluronic acid and collagen, which have moisturizing properties.

[0044] 2. Cleaning sheet impregnated with a water-based composition The aqueous composition of the present invention is primarily used as an aqueous composition for impregnating cleaning sheets. Cleaning sheets can be made by impregnating a base sheet made of woven or nonwoven fabric with the aqueous composition. Cleaning sheets impregnated with the aqueous composition of the present invention are not limited to wet sheets used for wiping the bottoms of infants or for wiping the bodies of sick people, the elderly, infants, etc., but also include all sheets used as wiping means such as makeup remover sheets, hand wipes, kitchen wipes, and cleaners for office automation products. These cleaning sheets require long-term storage stability from manufacturing to actual use, and furthermore, since they often come into contact with the skin during wiping, they also need to minimize skin irritation when used as cleaning sheets. Therefore, the aqueous composition of the present invention is required to have not only storage stability as an aqueous composition, but also storage stability and reduced skin irritation as a cleaning sheet obtained by impregnating a base sheet with the aqueous composition. A typical example of using the aqueous composition of the present invention as a cleaning sheet by impregnating a base sheet with it is described below.

[0045] (1) Base sheet As the base sheet for the cleaning sheet, woven or nonwoven fabrics can be used, but the use of nonwoven fabrics is preferred. Nonwoven fabrics are sheets in which fibers are intertwined without weaving, specifically by bonding or intertwining fibers through heat, physical, or chemical action to form a sheet. Examples of woven or nonwoven fabric materials include polypropylene fibers, polyethylene terephthalate fibers, polyamide fibers, rayon fibers, acrylic fibers, polyurethane fibers, pulp fibers (including paper), and composite fibers consisting of two or more of these, but the use of composite fibers is preferred in order to impart desirable functions to the base sheet.

[0046] When using composite fibers, it is preferable that they contain rayon fibers, which have high hygroscopicity and a pleasant feel. A preferred composite fiber is one composed of polyethylene terephthalate and rayon, in which case it is preferable that the composite fiber contains 40-60% by mass of rayon. Another example of a composite fiber is one composed of pulp and rayon, in which case it is preferable that the composite fiber contains 10-30% by mass of rayon. The basis weight of the nonwoven base sheet is 20-80 g / m². 2 Preferably, 30-60 g / m 2 This is preferable.

[0047] (2) Impregnation of the substrate sheet with an aqueous composition Methods for impregnating a substrate sheet with an aqueous composition include, but are not limited to, methods such as spraying the aqueous composition onto a dry substrate sheet, applying the aqueous composition using a roll containing the aqueous composition, or immersing the substrate sheet in the aqueous composition. From the viewpoint of ensuring the wiping function is achieved, the amount of water-based composition impregnated into the wiping sheet is preferably 100 to 300 parts by weight, and more preferably 150 to 270 parts by weight, per 100 parts by weight of the base sheet (based on dry weight). If the impregnation amount is less than 100 parts by weight, the water-based composition cannot be impregnated into the entire base sheet, which may hinder wiping. If the impregnation amount exceeds 300 parts by weight, the water-based composition cannot be fully impregnated into the base sheet, which may cause discomfort and other problems such as wet skin after wiping.

[0048] (3) pH of the aqueous phase of the cleaning sheet The pH of the aqueous phase in a cleaning sheet impregnated with the aqueous composition of the present invention, that is, the pH of the aqueous phase in a nearly equilibrium state after impregnation of the base sheet with the aqueous composition, is preferably 6.1 to 6.6 at 25°C. The pH of the aqueous phase is the pH value measured using a LAQUA twin pH meter manufactured by Horiba, Ltd. As described above, when the pH of the aqueous composition at 25°C is in the range of 3.47 to 3.83, for example, when impregnated into a nonwoven fabric sheet obtained from a composite fiber consisting of polyethylene terephthalate fibers and rayon fibers, it becomes possible to maintain the pH of the aqueous phase in the resulting cleansing sheet at a weakly acidic level of approximately 6.1 to 6.6, thereby reducing skin irritation when wiping the body with the cleansing sheet. On the skin's surface, beneficial bacteria such as Staphylococcus epidermidis, which are part of the normal flora of the skin, secrete fatty acids to maintain a slightly acidic pH, preventing the invasion of harmful bacteria and viruses. On the other hand, if the skin surface becomes alkaline, harmful bacteria such as Staphylococcus aureus become more active, which can increase the likelihood of skin problems.

[0049] The pH of the skin surface is maintained at a slightly acidic level of approximately 4.5 to 6.5, although there are individual differences, creating an environment where beneficial skin flora can easily thrive. Furthermore, since the pH of the skin surface of infants reaches approximately 6.0 to 7.0 after 5 to 6 weeks of age, it is preferable to maintain the pH of the aqueous phase in the cleansing sheet within this range. One of the features of this invention is that the pH of the aqueous phase in the cleansing sheet can be adjusted to a slightly acidic level by adjusting the blending ratio of benzalkonium chloride and polyaminopropyl biguanide hydrochloride, which are antibacterial components of the aqueous composition, without adding any pH adjusting agents. [Examples]

[0050] The aqueous compositions of the present invention will be specifically described by the following examples and comparative examples, but the aqueous compositions of the present invention are not limited to the following examples. First, the raw materials and samples used in these examples and comparative examples will be described. In these examples and comparative examples, evaluation tests were conducted on the "aqueous compositions" using these raw materials and samples, and further evaluation tests were conducted on "cleaning sheet test pieces" prepared by impregnating a base sheet with the aqueous compositions.

[0051] (1) Purified water Purified water with an electrical conductivity of 1 μS / cm or less was prepared by purifying ordinary water using an ion exchange resin. (2) Preservatives, solubilizers As components to be added to the aqueous composition, the preservative and solubilizer described below were used. Moreover, the pH was measured using a HORIBA pH METER F-21 manufactured by Horiba, Ltd. (i) Benzalkonium chloride is a commercially available product, and the pH of its 1% by mass aqueous solution was 7.91, and the pH of its 10% by mass aqueous solution was 8.93.

[0052] (ii) Polyaminopropyl biguanide hydrochloride is a commercially available product, and the pH of its 1% by mass aqueous solution was 3.26, the pH of its 10% by mass aqueous solution was 3.45, and the weight average molecular weight was 2000 - 3000. (iii) Glyceryl caprate is a commercially available product, and its property was a waxy mass. Since this component is poorly soluble in water, the pH measurement was not performed. (iv) Propynyl butylcarbamate was used as a commercially available product. (v) Polyethylene glycol is a commercially available product, and its number average molecular weight was 200. (vi) Propylene glycol was used as a commercially available product.

[0053] (3) Substrate sheet made of non-woven fabric The substrate sheet made of non-woven fabric has a basis weight of 32 g / m 2 and is a spunlace non-woven fabric made of a composite fiber composed of rayon fiber and polyethylene terephthalate fiber, and the content ratio of rayon fiber in the composite fiber is 40 - 60% by mass.

[0054] [Examples 1 - 9, Comparative Examples 1 - 8] 1. Evaluation test for aqueous composition In Examples 1 - 9 and Comparative Examples 1 - 8, first, an aqueous composition was prepared, and as an evaluation of the aqueous composition, (1) pH measurement, (2) observation of the occurrence of cloudiness or precipitate, and (3) preservation efficacy test were performed.

[0055] 1 - 1. Preparation of aqueous composition The aqueous compositions to be evaluated in Examples 1 - 9 and Comparative Examples 1 - 8 were prepared. Specifically, as shown in Tables 1 to 3, aqueous compositions were prepared by dissolving predetermined amounts of the preservative and solubilizer in the purified water according to each example and comparative example. Glyceryl caprate was pre-dissolved in the solubilizer before being added to the aqueous composition. Since the aqueous composition evaluated in Comparative Example 5 did not use a solubilizer, the waxy solid was ground up and added directly to the aqueous composition. Also, since Comparative Example 8 is a blank comparative example, the purified water described above was used as the aqueous composition. The evaluation of the aqueous composition prepared above is described below.

[0056] 1-2. Evaluation of aqueous compositions (1)pH measurement In Examples 1-9 and Comparative Examples 1-4 and 8, the pH of the prepared aqueous compositions at 25°C was measured using a pH measuring device (HORIBA pH METER F-21, manufactured by HORIBA, Ltd.). The pH measurement results are shown in Tables 1-3. The pH of the aqueous compositions in Examples 1-9 was in the range of 3.47-3.83. Furthermore, from Tables 1-3, it was confirmed that the pH value of the aqueous composition decreased as the mass ratio (b2 / b1) of the polyaminopropyl biguanide hydrochloride content (b2) to the benzalkonium chloride content (b1) increased.

[0057] (2) Observe whether or not turbidity or precipitate forms. In Examples 1-9 and Comparative Examples 1-7, aqueous compositions prepared with preservatives and solubilizers at the concentrations shown in Tables 1-3 were thoroughly stirred and then allowed to stand. The presence or absence of turbidity or precipitate was visually observed. The results of the observation regarding the presence or absence of turbidity or precipitate are shown in Tables 1-3. In Comparative Example 5, which did not contain a solubilizer, turbidity or precipitate was observed in the aqueous composition.

[0058] (3) Preservation efficacy test In Examples 1 to 9, the preservative efficacy tests of aqueous compositions were conducted in accordance with the test methods described in the "Preservative Efficacy Test Methods" of the 17th edition of the Japanese Pharmacopoeia. (i) Test method A preservative efficacy test involves adding a certain number of bacteria and fungi to an aqueous composition and measuring their numbers over time to confirm the preservative effect. The following three types of bacteria and two types of fungi, designated as test strains, were inoculated, and the number of viable cells was measured after 7, 14, and 28 days.

[0059] Test bacterial strains (bacteria) for antimicrobial testing (a) Escherichia coli (NBRC 3972) (b) Staphylococcus aureus (NBRC 12732) (c) Pseudomonas aeruginosa (12689) Test strains (fungi) for antifungal testing (d) Candida (NBRC 1385) (e) Aspergillus oryzae (NBRC 105649)

[0060] (ii) Evaluation method and evaluation results The evaluation was performed based on the rate of reduction in the number of inoculated bacteria. The method for calculating the reduction rate is shown below. Reduction rate (%) = [((Initial bacterial count) - (Viable bacterial count after 7, 14, and 28 days)) / Initial bacterial count] × 100 The evaluation results for the aqueous compositions prepared in Examples 1 to 9 are shown in Tables 1 and 2. In Tables 1 and 2, the blank column in the preservation efficacy test indicates the number of viable bacteria after 7 days, following the inoculation of a predetermined number of the above-mentioned bacteria and fungi into purified water instead of the aqueous composition. In Examples 1-5, the number of viable bacteria and fungi was measured after inoculation, respectively, at 7, 14, and 28 days. In Examples 6-9, the number of bacteria was measured at 7 days. In all of the preservation efficacy tests using the above-mentioned test bacterial strains, the rate of viable cell reduction after 7 days and beyond was 100%, confirming that the aqueous compositions prepared in Examples 1-9 possess excellent antibacterial and antifungal properties.

[0061] [Table 1]

[0062] [Table 2]

[0063] [Table 3]

[0064] The evaluation tests for the aqueous composition of the present invention are as described above. On the other hand, since the aqueous composition of the present invention is mainly used for impregnating cleaning sheets, tests were conducted on the storage stability and skin irritation of cleaning sheets impregnated with the aqueous composition. The test methods and results are described below.

[0065] 2. Evaluation test of a cleaning sheet impregnated with a water-based composition. The aqueous compositions prepared in Examples 1-9 and Comparative Examples 1-4 and 6-8 were impregnated into a base sheet to create a cleaning sheet test specimen. The resulting cleaning sheet test specimens were then subjected to the following storage stability tests and evaluations regarding skin irritation. (i) Storage stability test As part of the storage stability testing, antibacterial tests (in accordance with JIS L 1902), antifungal tests (in accordance with JIS L 1921), and mold resistance tests (in accordance with JIS Z 2911) were conducted.

[0066] Regarding the evaluation of the antifungal properties of the cleaning sheet test pieces, in Examples 1 to 4, a quantitative evaluation of antifungal properties, the "Antifungal Properties Test (in accordance with JIS L 1921)," was performed to clarify the superiority over the comparative examples. In Examples 5 to 9, since superiority over the comparative examples was anticipated, a qualitative evaluation of antifungal properties, the "Mold Resistance Test (in accordance with JIS Z 2911)," was performed. (ii) Evaluation regarding skin irritation As part of the evaluation of the skin irritation test, the pH of the aqueous phase portion of the cleansing sheet test piece was measured, and a primary skin irritation test was performed.

[0067] 2-1. Preparation of cleaning sheet test specimens The above-mentioned base sheet, cut to a predetermined size, is impregnated with the aqueous composition prepared in the above examples and comparative examples by hand spraying, with an impregnation rate of 80 g / m². 2 The mixture was sprayed uniformly to prepare cleaning sheet test pieces for evaluation in Examples 1-9 and Comparative Examples 1-4 and 6-8. The base sheet was impregnated with the aqueous composition and then sterilized using ultraviolet light.

[0068] 2-2. Evaluation Test of Cleansing Sheet Test Pieces (1) pH measurement of the aqueous phase of the cleaning sheet test piece In Examples 1-9 and Comparative Examples 1-4 and 8, the aqueous compositions prepared were impregnated into base sheets to create cleaning sheet test pieces, which were then left to stand for approximately 60 minutes. Subsequently, the cleaning sheet test pieces were squeezed using a padding machine (mangle), and the extract was maintained at room temperature (25°C). The pH was then measured using a pH measuring device (LAQUA twin pH meter, manufactured by Horiba, Ltd.). The measurement results are shown in Tables 4-6. The pH of the aqueous phase of the cleaning sheet test pieces impregnated with the aqueous compositions prepared in Examples 1 to 9 was in the range of 6.1 to 6.6 in all cases.

[0069] (2) Antimicrobial test The cleaning sheet test pieces obtained by impregnating the base sheets with the aqueous compositions prepared in Examples 1-9 and Comparative Examples 1-4 and 6-8 were subjected to antibacterial testing in accordance with JIS L 1902 (2015). JIS L 1902 is a qualitative test for evaluating the antibacterial properties of antibacterial fibers and specifies the method for evaluating the antibacterial activity of all antibacterial fiber products, including nonwoven fabrics. (i) Examination method The following two types of bacteria were used as test subjects. Escherichia coli (NBRC 3301) Staphylococcus aureus (NBRC 12732) Agar plates containing Escherichia coli and Staphylococcus aureus were placed in petri dishes and allowed to solidify. A cleansing sheet test piece was placed in the center of the petri dish. The petri dish was left at 37°C for 48 hours, and once the bacteria had grown on the medium, the width (mm) of the inhibition zone (halo) formed around the test piece where bacteria did not grow was measured on all four sides, and the average value was calculated.

[0070] (ii) Evaluation results Tables 4-6 show the halo widths measured for the test bacteria, Escherichia coli and Staphylococcus aureus. The criteria for determining the presence or absence of a halo, based on JIS L 1902, are as follows: When the average width of the halo > 0: Halo present When the average width of the halo is 0: No halo. In Examples 1 to 9, the antimicrobial test results were all judged as "halo present."

[0071] (3) Antifungal test The cleaning sheet test pieces obtained by impregnating the aqueous compositions prepared in Examples 1-4 and Comparative Example 4 with each substrate sheet were subjected to antifungal testing in accordance with JIS L 1921 (2015). The antifungal test is a quantitative testing method that examines the antifungal ability to kill a certain amount of mold in a relatively short time.

[0072] (i) Overview of the exam A spore suspension for the test is prepared by collecting spores from a pre-cultured test mold. Next, the test spore suspension is inoculated onto a cleaning sheet test piece and a control sample (cotton standard cloth), respectively, and the amount of ATP is measured after incubation at 25°C for 18 and 24 hours to determine the amount of mold surviving on the sample. By comparing the amount of mold on the cleaning sheet test piece and the control sample, the "antifungal activity value," which indicates how well mold growth was suppressed, is calculated. Note that measuring the amount of ATP refers to making ATP (adenosine triphosphate) present in the cells of an organism emit light using enzymes, etc., and measuring the amount of light emitted. The amount of light emitted increases as the amount of ATP in the cell increases. The "antifungal activity value" can be calculated using the following formula. Antifungal activity value (Aa): (Fb-Fa)-(Fc-Fo) Fb: Common logarithm of the arithmetic mean of ATP levels after 42 hours of incubation of untreated cotton fibers. Fa: Common logarithm of the arithmetic mean of ATP levels immediately after inoculation of untreated cotton fibers. Fc: Common logarithm of the arithmetic mean of ATP levels after 42 hours of incubation of the cleansing sheet test specimen. Fo: Common logarithm of the arithmetic mean of ATP levels immediately after inoculation of the cleansing sheet test piece.

[0073] (ii) Test mold species The following mold species were selected for testing. Aspergillus oryzae (NBRC 105649) (iii) Evaluation criteria and evaluation results The antifungal activity value (Aa) indicates that a higher value indicates better antifungal performance, and according to the evaluation criteria, a value of 2.0 or higher is considered to have antifungal properties. Table 4 shows the antifungal activity values ​​(Aa) calculated for Examples 1-4 and Comparative Example 4. From Table 4, it can be seen that the cleaning sheet test pieces of Examples 1-4 all had an antifungal activity value (Aa) of 2.0 or higher, confirming superior antifungal properties compared to the cleaning sheet test piece of Comparative Example 4.

[0074] (4) Mold resistance test The cleaning sheet test pieces obtained by impregnating each of the aforementioned aqueous compositions onto a base sheet were evaluated according to the mold resistance test (JIS Z 2911 (2018)). The mold resistance test is a qualitative test that evaluates the resistance of a test piece to mold, and it is possible to evaluate the mold resistance of the test piece over a relatively long incubation period. (i) Overview of the exam Mold resistance tests were conducted on cleaning sheet test pieces obtained by impregnating a base sheet with the aqueous compositions prepared in Examples 5-9 and Comparative Examples 1-3 and 8. In addition, since the antifungal properties were already evaluated in the antifungal properties test described above for Examples 1-4 and Comparative Example 4, the mold resistance test was omitted. The test specimens were placed on an inorganic salt medium in a petri dish, and the spore suspension of the following mold was evenly sprayed onto the surface of the specimens. After incubation at 28±4°C for 4 weeks, the growth of mycelium on the specimens was observed with the naked eye and under a microscope.

[0075] (ii) Test mold The following were used: (a) one type of mold and (b) a mixture of three types of mold. (a) Aspergillus niger NBRC 105649 (b) Mixture of 3 types Penicillium citrinum (NBRC 6352) Chaetomium globosum (NBRC 6347) Myrothecium verrucaria (NBRC 6113)

[0076] (iii) Criteria for evaluation and results Based on JIS Z 2911 (2018), the criteria for determining the state of mold growth are shown in the following three stages, with a rating of "0 or 1" indicating mold resistance. 0: No mycelial growth was observed in the inoculated area of ​​the test specimen. 1: The area of ​​mycelium observed in the inoculated portion of the test specimen does not exceed 1 / 3 of the total area. 2: The area of ​​mycelium observed in the inoculated portion of the test specimen exceeds 1 / 3 of the total area. The evaluation results based on the above criteria are shown in Tables 5 and 6. From Tables 5 and 6, it can be seen that the mold growth status of the cleaning sheet test pieces prepared in Examples 5 to 9 was all judged as 1, and it was confirmed that they had superior mold resistance compared to the cleaning sheet test pieces prepared in Comparative Examples 1 to 3 and 8.

[0077] [Table 4]

[0078] [Table 5]

[0079] [Table 6]

[0080] (5) Skin irritation test A primary skin irritation test was conducted in accordance with the "Guidelines for Safety Evaluation of Cosmetics" issued by the Japan Cosmetic Industry Association. A primary skin irritation test was performed on cleaning sheet test pieces prepared by impregnating them with the aqueous composition prepared in Example 6, and on cleaning sheet test pieces prepared by impregnating them with the same aqueous composition as prepared in Example 6 (Example 11), except that the aqueous composition prepared in Example 6 contained 0.0500% by mass of benzalkonium chloride, 0.0500% by mass of polyaminopropyl biguanide hydrochloride, 0.0300% by mass of glyceryl caprate, and 0.0100% by mass of polyethylene glycol.

[0081] (i) Test method Twenty healthy male and female subjects had skin test tapes (evaluation cleansing sheets) applied to the normal skin on their backs. After 24 hours, the skin test tapes were removed, and the skin condition was visually inspected and evaluated according to the following criteria. No response: 0.0 points Slight erythema: 0.5 points Obvious erythema: 1.0 points Erythema and edema or papules: 2.0 points Erythema and edema, papules and vesicles: 3.0 points Large blister: 4.0 points

[0082] (ii) Skin irritation index and determination The evaluation score for each subject was determined, and the skin irritation index was calculated using the following formula. Skin irritation index = (sum of scores / number of subjects) × 100 Next, the safety of the cosmetic product was determined based on the calculated skin irritation index, using the following classification system (safe product: 5.0 or less, acceptable product: 5.0 to 15.0, product requiring improvement: 15.0 to 30.0, dangerous product: 30.0 or higher). The evaluation results showed that the skin irritation index of the cleansing sheet test pieces prepared in Examples 6 and 11 was 2.5 or less in all cases, and they were classified as "safe products."

Claims

1. A water-based composition for impregnating cleaning sheets, comprising purified water, benzalkonium chloride and polyaminopropyl biguanide hydrochloride as preservatives, which are antimicrobial components, and glyceryl caprate as an antifungal component, and a solvent that solubilizes glyceryl caprate as a solubilizer, In the aqueous composition, the content of benzalkonium chloride (b1) is 0.030% by mass or more and 0.050% by mass or less, the content of polyaminopropyl biguanide hydrochloride (b2) is 0.025% by mass or more and 0.070% by mass or less, and the content of glyceryl caprate (c1) is 0.003% by mass or more and 0.050% by mass or less. Furthermore, the concentration of purified water in the aqueous composition is 99.85% by mass or more and 99.92% by mass or less. A water-based composition characterized by the following features.

2. In the aqueous composition, the total amount of benzalkonium chloride (b1) and polyaminopropyl biguanide hydrochloride (b2) (b1 + b2) is 0.060 or more and 0.105% by mass or less, and the mass ratio of polyaminopropyl biguanide hydrochloride (b2) to benzalkonium chloride (b1) (b2 / b1) is 0.625 or more and 2.00 or less. The aqueous composition according to claim 1.

3. The aqueous composition according to claim 1 or 2, wherein the mass ratio (c1 / (b1+b2)) of the content of glyceryl caprate, which is an antifungal agent component (c1), to the total amount (b1+b2) of the content of benzalkonium chloride, which is an antibacterial agent component (b1), and the content of polyaminopropyl biguanide hydrochloride, which is an antibacterial agent component (b2), is 0.035 or more and 0.833 or less.

4. The aqueous composition according to any one of claims 1 to 3, wherein the mass ratio (d1 / c1) of the content of a solvent for solubilizing glyceryl caprate (d1) to the content of glyceryl caprate, which is an antifungal agent component, (c1) is 0.60 or more and 2.14 or less.

5. The pH of the aqueous composition at 25°C is 3.47 or higher and 3.83 or lower. The aqueous composition according to any one of claims 1 to 4.

6. The aqueous composition according to any one of claims 1 to 5, wherein the solvent for solubilizing the glyceryl caprate is a polyether having an OH-terminated group and is liquid at room temperature of 15 to 25°C.

7. The aqueous composition according to any one of claims 1 to 6, wherein the solvent for solubilizing the glyceryl caprate is polyethylene glycol having a number average molecular weight of 100 or more and 600 or less.

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