JP2024048620A - External preparation composition and method for producing same - Google Patents

Abstract

[Problem] To provide an external preparation composition that contains 30% by mass or more of a water-soluble moisturizing agent such as urea, and has excellent emulsion stability even when stored at high temperatures. [Solution] The external preparation composition is an O/W type emulsion containing (A) 30% by mass or more of a water-soluble moisturizing component and (B) a carboxyvinyl polymer, and has a viscosity of 4,000 mPa·s or less at 25°C, in which the component (B) is a carboxyvinyl polymer having a critical strain of 35.0% or more, calculated from the intersection of the straight line representing the storage modulus G' in the strain range of 0.3 to 1% and the straight line representing the storage modulus G' in the strain range of 80 to 300%, when the storage modulus G' is measured in a 0.4% by mass aqueous solution (pH 7.0) at 25°C, in a strain range of 0.01 to 1,000%, and at a frequency of 1 Hz. [Selected Figure] Figure 1

Description

The present invention relates to a topical composition containing 30% by mass or more of a water-soluble moisturizing component and a method for producing the same.

When making emulsions, stabilizing the emulsion is an important issue. Depending on the composition of the emulsion and the manufacturing method, creaming and aggregation may occur over time, and over time, oil-water separation into an oil phase and an aqueous phase may occur. Once phase separation occurs, it cannot be restored to its original state, so it is necessary to design a formulation that is less likely to cause oil-water separation.

Various technologies have been developed to suppress oil-water separation and improve stability. For example, there is a method that uses a water-soluble polymeric compound as a thickener. This method is based on increasing the viscosity of the dispersion medium in the formulation and suppressing the rate of aggregation of dispersed particles. Among these thickeners, carboxyvinyl polymer, a synthetic polymeric compound, is widely used in emulsion compositions because it has excellent emulsifying properties in addition to thickening properties and also ensures uniformity of quality.

JP 2019-182839 A

However, in a composition containing 30% by mass or more of a water-soluble moisturizer such as urea, even if it contains a carboxyvinyl polymer, it is difficult to ensure emulsion stability, and there is a problem with emulsion stability during storage at high temperatures in particular. The present invention has been made in consideration of the above circumstances, and aims to provide a topical composition that contains 30% by mass or more of a water-soluble moisturizer such as urea and has excellent emulsion stability even during storage at high temperatures.

As a result of intensive research to achieve the above object, the present inventors have found that by using a specific carboxyvinyl polymer in an external preparation composition containing 30% by mass or more of a water-soluble moisturizing agent, oil-water separation, particularly during high-temperature storage, can be suppressed, and an external preparation composition having excellent emulsion stability can be obtained even when stored at high temperatures. In addition, by including a carboxyvinyl polymer in an external preparation composition containing 30% by mass or more of a water-soluble moisturizing agent so that the viscoelasticity of the composition is within a specific range, oil-water separation, particularly during high-temperature storage, can be suppressed, and an external preparation composition having excellent emulsion stability can be obtained even when stored at high temperatures, and this has led to the present invention.

Therefore, the present invention provides the following topical composition and method for producing the same.
1. A topical composition which is an O/W type emulsion containing (A) 30% by mass or more of a water-soluble moisturizing component and (B) a carboxyvinyl polymer, and has a viscosity of 4,000 mPa·s or less at 25°C,
The component (B) is a carboxyvinyl polymer having a critical strain of 35.0% or more, which is calculated from the intersection of a straight line representing the storage modulus G' in a strain range of 0.3 to 1% and a straight line representing the storage modulus G' in a strain range of 80 to 300%, when the storage modulus G' is measured in a 0.4% by mass aqueous solution (pH 7.0) at 25°C, a strain range of 0.01 to 1,000%, and a frequency of 1 Hz.
2. The topical composition according to 1, wherein the component (A) is one or more selected from the group consisting of polyhydric alcohols, sugars, sugar alcohols and urea.
3. The topical composition according to 1 or 2, wherein the content of component (B) is 0.05 to 1% by mass.
4. An external preparation composition which is an O/W type emulsion containing (A) 30% by mass or more of a water-soluble moisturizing component and (B') a carboxyvinyl polymer, and has a viscosity of 4,000 mPa·s or less at 25°C, and which, when the storage modulus G' is measured at 25°C, in a strain range of 0.01 to 1,000%, and at a frequency of 1 Hz, has a critical strain of 20.0% or more calculated from the intersection of the straight line representing the storage modulus G' in a strain range of 0.1 to 0.5% and the straight line representing the storage modulus G' in a strain range of 100 to 300%.
5. The topical composition according to 4, wherein the component (A) is one or more selected from the group consisting of polyhydric alcohols, sugars, sugar alcohols and urea.
6. A method for producing an external preparation composition, which is an O/W type emulsion containing (A) 30% by mass or more of a water-soluble moisturizing component and (B) a carboxyvinyl polymer, and has a viscosity of 4,000 mPa·s or less at 25°C, comprising:
the component (B) is a carboxyvinyl polymer having a critical strain of 35.0% or more, calculated from the intersection of a straight line representing the storage modulus G' in a strain range of 0.3 to 1% and a straight line representing the storage modulus G' in a strain range of 80 to 300%, when the storage modulus G' is measured in a 0.4% by mass aqueous solution (pH 7.0) at 25°C, a strain range of 0.01 to 1,000%, and a frequency of 1 Hz;
A method for producing an external preparation composition, comprising the step of mixing the component (A) and the component (B).

According to the present invention, it is possible to provide an external preparation composition that contains 30% by mass or more of a water-soluble moisturizing agent such as urea and has excellent emulsion stability even when stored at high temperatures.

1 is a graph showing the measurement results of the critical strain of component (B): Syntharen L (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

The present invention will be described in detail below.
[Component (A)]
The component (A) of the present invention is a water-soluble moisturizing component, and may be used alone or in combination of two or more. Water-soluble means that it is miscible with water in any ratio and clear, or that less than 1 mL of water is required to dissolve 1 g or 1 mL of solute. The component (A) is not particularly limited, but examples thereof include polyhydric alcohols, sugars, sugar alcohols, and urea. Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, hexylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, isoprene glycol, glycerin, diglycerin, triglycerin, tetraglycerin, hexaglycerin, decaglycerin, 1,3-butylene glycol, trimethylolpropane, erythritol, pentaerythritol, dipentaerythritol, and sorbitan. Examples of sugars include glucose, mannose, galactose, sucrose, fructose, and maltose. Examples of sugar alcohols include maltitol, xylitol, inositol, and sorbitol. Of these, glycerin, 1,3-butylene glycol, propylene glycol, and urea are preferred.

The content of component (A) in the topical composition is 30% by mass or more, preferably 30 to 60% by mass, more preferably 30 to 50% by mass, and even more preferably 30 to 45% by mass. By making the content 30% by mass or more, it becomes easier to obtain a moisturizing effect, and by making it 60% by mass or less, it is possible to obtain better emulsion stability.

[Component (B)]
The component (B) of the present invention is a carboxyvinyl polymer having a critical strain of 35.0% or more, calculated from the intersection of a straight line of the storage modulus G' in a strain range of 0.3 to 1% and a straight line of the storage modulus G' in a strain range of 80 to 300%, when the storage modulus G' is measured in a 0.4% by mass aqueous solution (pH 7.0) at 25°C, in a strain range of 0.01 to 1,000%, and at a frequency of 1 Hz, and can be used alone or in combination of two or more. The critical strain value is 35.0% or more, more preferably 35.0 to 100%, and even more preferably 37 to 90%. By using a carboxyvinyl polymer having such a specific critical strain value, emulsion stability can be maintained even in a topical composition containing 30% by mass or more of a water-soluble moisturizing agent.

The critical strain is the strain at which the storage modulus G' of the measured sample transitions from linear to nonlinear (structural destruction begins). In the case of polymer compounds such as carboxyvinyl polymer, it is due to the strength of the crosslinking points of the network, and the larger the value, the stronger the network that is less likely to collapse. The inventors have found that there is a positive correlation between the emulsion stability of the topical composition containing 30% by mass or more of the water-soluble moisturizing component of the present invention and the critical strain value of the carboxyvinyl polymer raw material, and have found that high emulsion stability can be obtained, especially when a carboxyvinyl polymer with a certain or higher critical strain is used as the raw material. This phenomenon is believed to be due to the fact that carboxyvinyl polymers with low critical strain values are relatively prone to aggregation, and the emulsion particles and water-soluble moisturizing components cannot be completely captured in the swollen carboxyvinyl polymer network structure, which makes it easier for oil-water separation to occur over time, resulting in poor emulsion stability.

The component (B) of the present invention defines the galboxyvinyl polymer by the critical strain, and although there is no direct relationship with the viscosity, the viscosity of a 0.2% aqueous solution at 25°C is preferably 1,500 to 30,000, more preferably 1,500 to 10,000. The viscosity is measured using a BH viscometer at 10 rpm, rotor No. 3, 1 minute, and 25°C, and is measured the day after the aqueous solution is prepared. The viscosity immediately after the topical composition is the viscosity the day after production (after about 24 hours at room temperature) (the same applies below).

Typical patterns of change over time in O/W emulsions include creaming, in which emulsified particles in the emulsion float or settle, aggregation, coalescence, and phase separation. In particular, with regard to suppression of creaming, it is generally said that liquid separation is less likely to occur when the viscosity is increased, based on Stokes' equation (u=(2a ² (ρ1-ρ0)g)/η; u: settling (floating) velocity, a: particle radius, g: gravitational acceleration, η: viscosity of the continuous phase, ρ0: density of the continuous phase, ρ1: density of the dispersed phase), which indicates the terminal velocity when small particles settle in a fluid. However, if the viscosity is increased, there is a concern that the topical preparation composition becomes difficult to spread on the skin, resulting in a deterioration in usability, and depending on the topical preparation composition, even if the viscosity is increased, the emulsion stability may not necessarily be improved. However, by using a carboxyvinyl polymer with a certain critical strain or more, it is possible to obtain an topical preparation composition with excellent emulsion stability, even if the topical preparation composition has a low viscosity.

The method for measuring the critical strain will be described in detail. A 0.4% by weight aqueous solution of carboxyvinyl polymer is used as the sample (adjusted with a basic component so that the pH is 7.0, 25°C). The measuring device is a rheometer, for example, a stress-controlled cone-plate rheometer AR2000ex (manufactured by TA Instruments Japan Co., Ltd.) with a 40 mm aluminum cone plate. When the storage modulus is measured under the conditions of temperature: 25°C, strain range: 0.01 to 1,000%, and frequency: 1 Hz, the critical strain γcr, which is the strain value at the point where the storage modulus G' transitions from the linear to nonlinear region, is obtained from the intersection point between the straight line of the storage modulus G' in the strain range of 0.3 to 1% and the straight line of the storage modulus G' in the strain range of 80 to 300%.

The content of component (B) in the topical composition is preferably 0.05 to 1% by mass, more preferably 0.1 to 0.8% by mass, and even more preferably 0.3 to 0.6% by mass. By making the content equal to or greater than the above lower limit, the emulsion stability can be further improved. By making the content equal to or less than the above upper limit, the topical composition can be more easily spread on the skin.

[External application composition]
The topical composition of the present invention is an O/W type emulsion, and has a viscosity at 25°C of 4,000 mPa·s or less, preferably 500 to 4,000 mPa·s, more preferably 800 to 2,500 mPa·s, and even more preferably 1,000 to 2,000 mPa·s. By setting the viscosity at or above the lower limit, the emulsion stability can be further improved. If the viscosity of the topical composition exceeds 4,000 mPa·s, problems arise in the feel during use, such as difficulty in spreading and stickiness.

The topical composition has a viscosity of 4,000 mPa·s or less at 25°C, and preferably has a storage modulus G' of 100 Pa or less at 25°C, a strain range of 0.01 to 1,000%, and a frequency of 1 Hz. Under these measurement conditions, the critical strain calculated from the intersection of the straight line of the storage modulus G' in the strain range of 0.1 to 0.5% and the straight line of the storage modulus G' in the strain range of 100 to 300% is preferably 20.0% or more, more preferably 20.0 to 100%, and even more preferably 22 to 90%. When the above-mentioned specified value of the topical composition is 20.0% or more, emulsion stability is further improved, and when it is 100% or less, the usability is improved.

The storage modulus G' of the topical composition is measured using a rheometer, for example, a stress-controlled cone-plate rheometer AR2000ex (manufactured by TA Instruments Japan Co., Ltd.), with a 40 mm aluminum cone plate, under conditions of strain: 0.01 to 1,000%, frequency: 1 Hz, and temperature: 25°C. The critical strain γcr of the topical composition is the critical strain γcr, which is the strain value at the point where the storage modulus G' transitions from the linear to nonlinear region when strain dependency is measured using the above-mentioned equipment and conditions (the intersection point between the straight line of the storage modulus G' in the strain range of 0.1 to 0.5% and the straight line of the storage modulus G' obtained from the strain range of 100 to 300%).

The pH (25°C) of the topical composition is preferably 5 to 9.5, and more preferably 6 to 9. When the pH of the topical composition is equal to or higher than the lower limit, emulsion stability is improved, and when the pH is equal to or lower than the upper limit, skin irritation is less likely to occur.

The present invention provides an external preparation composition that is an O/W type emulsion containing (A) 30% by mass or more of a water-soluble moisturizing component and (B') a carboxyvinyl polymer, and has a viscosity of 4,000 mPa·s or less at 25°C, and in which, when the storage modulus G' is measured at 25°C, in a strain range of 0.01 to 1,000%, and at a frequency of 1 Hz, the critical strain calculated from the intersection of the straight line of G' obtained from a strain range of 0.1 to 0.5% and the straight line of G' obtained from a strain range of 100 to 300% is 20.0% or more.

In this topical preparation composition, the carboxyvinyl polymer (B') is not limited to the above-mentioned (B) component, and any known carboxyvinyl polymer used in topical preparations can be used, but the above-mentioned (B) component can be preferably used. The method for measuring the viscosity and storage modulus of the (A) component and the topical preparation composition is the same as above.

[Optional ingredients]
The topical composition of the present invention may contain various active ingredients used in medicines, quasi-drugs, cosmetics, etc., as necessary, within the scope of not impairing the effects of the invention. Examples include anti-inflammatory agents, antihistamines, herbal ingredients, antipruritic agents, wound healing agents, local anesthetics, vitamins, cooling agents, moisturizers other than component (A), bactericides, vasoconstrictors, and amino acids. These may be used alone or in combination of two or more. Specific examples of the ingredients include the following. Note that when an ingredient has multiple effects, they may be described multiple times.

Anti-inflammatory agents include glycyrrhetinic acid, glycyrrhizinic acid or its derivatives, licorice extract, steroid compounds (hydrocortisone, prednisolone, methylprednisolone, clobetasone, betamethasone, dexamethasone, cortisone, flumethasone, beclomethasone, fluticasone or their derivatives), indomethacin, ibuprofen, ibuprofen piconol, bufexamac, ufenamate, piroxicam, ketoprofen, salicylic acid or its derivatives, dimethylisopropylazulene, angelica extract, and lithospermum root extract.

Antihistamines include diphenhydramine, chlorpheniramine, mequitazine, azelastine, emedastine, ketotifen, or derivatives thereof. Preferred are diphenhydramine, diphenhydramine hydrochloride, and chlorpheniramine maleate.

Examples of herbal ingredients include artichoke leaf extract, althea root extract, arnica flower extract, aloe vera leaf extract, ginkgo leaf extract, unshu mandarin peel extract, scutellaria root extract, ginseng root extract, hypericum flower/leaf/stem extract, olive leaf extract, orange fruit extract, brown algae extract, chamomile flower extract, licorice extract, rubus idaeus fruit extract, amplexicaule bark extract, cucumber fruit extract, gardenia fruit extract, sophora flavescens root extract, grapefruit fruit extract, chlorella extract, rice bran extract, hawthorn extract, peony root extract, ginger root extract, white birch bark extract, horsetail extract, and ivy. Leaf/stem extract, yarrow extract, peppermint leaf extract, sage leaf extract, mallow flower extract, rosa centifolia flower extract, swertia japonica extract, mulberry bark extract, soybean seed extract, tea leaf extract, angelica root extract, calendula officinalis flower extract, rose multiflora fruit extract, coix seed extract, hamamelis leaf extract, loquat leaf extract, prune hydrolyzate, safflower flower extract, peony extract, horse chestnut extract, peach leaf extract, centaurea cyanus flower extract, eucalyptus leaf extract, saxifrage extract, yuzu fruit extract, lavender flower extract, apple fruit extract, lemon fruit extract, rosemary leaf extract, etc.

Antipruritic agents include salicylic acid or its derivatives, vanillylamide nonylate, capsaicin, benzyl nicotinate, capsicum tincture, lidocaine, etc.

Wound healing agents include allantoin, zinc oxide, etc.

Local anesthetics include lidocaine, lidocaine hydrochloride, methyl aminobenzoate, ethyl aminobenzoate, dibucaine, dibucaine hydrochloride, etc.

Vitamin preparations include vitamin A [retinol and its derivatives (e.g., retinal, retinoic acid, retinol palmitate, etc.)], vitamin B1 [thiamine and its derivatives (e.g., thiamine hydrochloride, thiamine nitrate, etc.)], vitamin B2 [riboflavin and its derivatives (e.g., riboflavin phosphate, riboflavin sodium phosphate, riboflavin butyrate, and flavin adenine dinucleotide sodium)], vitamin B3 [nicotinic acid and its derivatives (nicotinamide, tocopherol nicotinate, benzyl nicotinate, etc.)], vitamin B5 [pantothenic acid and its derivatives (e.g., calcium pantothenate, panthenol, pantothenyl ethyl alcohol)], vitamin B6 [pyridoxine and its derivatives (e.g., pyridoxine hydrochloride, pyridoxine phosphate, pyridoxamine, pyridoxal, and pyridoxine phosphate)], sar, etc.)], vitamin B12 [cobalamin and its derivatives (e.g., cyanocobalamin, mecobalamin, and hydroxocobalamin hydrochloride, etc.)], biotin, folic acid or a pharma- ceutical acceptable salt thereof, vitamin C [ascorbic acid and its derivatives (e.g., erythorbic acid, sodium ascorbate, ascorbic acid palmitate, ascorbic acid glucoside, etc.)], vitamin D [calciferol and its derivatives (e.g., ergocalciferol, cholecalciferol, etc.)], vitamin E [tocopherol, ubiquinone and its derivatives (e.g., tocopherol acetate, tocopherol calcium succinate, etc.)], other vitamins (e.g., hesperidin, carnitine, ferulic acid, γ-oryzanol, orotic acid, rutin, eriocitrin, inositol, and a pharma-ceutical acceptable salt thereof), etc.

Examples of cooling agents include menthol, camphor, borneol or related substances, fennel oil, eucalyptus oil, peppermint oil, etc.

Moisturizing agents include polyhydric alcohols other than component (A) (1,2-hexanediol, glycerin triisooctanoate, etc.), hyaluronic acid or its derivatives, heparinoids, polymeric compounds (collagen, chitosan, etc.), amino acids (glycine, alanine, aspartic acid, etc.), natural moisturizing factors (sodium lactate, sodium pyrrolidone carboxylate, etc.), ceramides, plant extracts (chamomile extract, aloe extract, etc.), etc.

Bactericides include isopropyl methylphenol, chlorhexidine hydrochloride, benzethonium chloride, benzalkonium chloride, cetrimide, etc.

Vasoconstrictors include naphazoline, tetrahydrozoline, methylephedrine, or their salts.

Examples of amino acids include glutamic acid, aspartic acid, glycine, alanine, serine, aminoethylsulfonic acid (taurine), and pharma- ceutical acceptable salts or derivatives thereof (e.g., arginine hydrochloride, glycylglycine, etc.). The inclusion of these amino acids improves the moisturizing effect.

When the topical composition contains the above-mentioned active ingredients, the content ratio is appropriately set according to the effective dose of each active ingredient.

[Production method]
The topical composition of the present invention can be obtained by a manufacturing method including a step of mixing the above-mentioned (A) component and (B) component. In addition, the composition can be prepared by blending water (the remainder), base components, stabilizers, pH adjusters, preservatives, surfactants, the above-mentioned optional components, etc., according to a conventional method. In order to dissolve the (B) component uniformly in the topical composition, it is preferable to mix the (B) component with an oily base such as fatty acid ester oil or silicone oil among the bases described below to prepare a premix, and then mix it with the (A) component and a water-soluble base. Any of the raw materials generally used as a base can be used to prepare the topical composition of the present invention. These can be used alone or in combination of two or more. The same applies when the carboxyvinyl polymer is (B').

Examples of bases include hydrocarbons such as petrolatum, paraffin, liquid paraffin, squalane, ceresin, gelling hydrocarbons, and microcrystalline wax; higher fatty acids such as lauric acid, palmitic acid, stearic acid, isostearic acid, myristic acid, oleic acid, behenic acid, and behenic acid; higher fatty alcohols such as cetanol, stearyl alcohol, isostearyl alcohol, and behenyl alcohol; fatty acid ester oils such as isopropyl myristate, octyldodecyl myristate, isopropyl palmitate, triethylhexanoin, cetyl ethylhexanoate, and diisopropyl adipate; oils and fats such as hydrogenated oil, coconut oil, and olive oil; polyhydric alcohol fatty acid esters such as glycerin triisooctanoate and tri(capryl-capric acid)glyceryl; silicone oils such as dimethylpolysiloxane, cyclopentasiloxane, and diphenyl dimethicone; and organic solvents such as ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, and ethyl acetate. When these bases are included, the content is preferably 5 to 40% by mass in the topical composition.

Examples of stabilizers include sodium chloride, sodium thiosulfate, sodium sulfite, and sodium edetate; examples of pH adjusters include diisopropanolamine, triethanolamine, sodium hydroxide, lactic acid, hydrochloric acid, citric acid, sodium citrate, potassium dihydrogen phosphate, and sodium hydrogen phosphate; examples of preservatives include methylparaben, propylparaben, butylparaben, benzalkonium chloride, and benzethonium chloride. When these stabilizers are contained, the content of the topical composition is preferably 0.001 to 2% by mass. When these preservatives are contained, the content of the topical composition is preferably 0.001 to 1% by mass.

Examples of surfactants that can be used include non-ionic surfactants such as glyceryl monostearate, glyceryl monooleate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monooleate, polyoxyethylene (60) sorbitan tetrastearate, polyoxyethylene (60) sorbitan tetraoleate, decaglyceryl pentastearate, polyoxyethylene (60) castor oil, polyoxyethylene (60) hydrogenated castor oil, polyoxyethylene glycol (4EO) monostearate, polyethylene glycol (10EO) monooleate, polyethylene glycol (20EO) monolaurate, polyoxyethylene (9) lauryl ether, polyoxyethylene (10) cetyl ether, and polyoxyethylene oleyl ether, and ionic surfactants such as sodium lauryl sulfate, sodium cetyl sulfate, and sodium laureth sulfate. Among these, nonionic surfactants are preferred because they reduce skin irritation.

When a surfactant is contained, its content in the topical preparation composition is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass. By making it 0.1% by mass or more, it becomes easier to spread on the skin and the emulsion stability is further improved. By making it 10% by mass or less, the viscosity is less likely to increase and the feel when applied to the skin is improved.

[Scope of application of topical composition]
The topical composition may be a medicine, a quasi-drug, or a cosmetic, and is not particularly limited, and may be applied to the skin in general, including the scalp and face.

The present invention will be specifically explained below with examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, unless otherwise specified, "%" in the composition indicates mass %.

[Examples and Comparative Examples]
The production equipment used was a Mizuho vacuum emulsifier (PVQ-3UN).
The aqueous phase components excluding component (A) and sodium hydroxide were mixed in the main kettle in the ratios shown in the examples in the table below until the mixture became clear, and a bulk mixture of component (A) and aqueous phase components was obtained (however, water was 25%). Note that component (B) was dispersed in the total amount of dimethylpolysiloxane contained in the oil phase components and about 1/3 of the amount of isopropyl myristate, and then added to the bulk mixture of component (A) and aqueous phase components, and stirred for 45 seconds under reduced pressure conditions with an ultramixer at 5,500 rpm and an anchor at 120 rpm. Thereafter, the mixture was mixed with an anchor under reduced pressure conditions until the temperature reached 70°C. Separately, the remaining total amount of the oil phase components was mixed while heating to 70°C to obtain an oil phase, which was then further added to the main kettle and emulsified and mixed for 50 seconds under normal pressure with an ultramixer at 10,000 rpm and an anchor at 120 rpm. Thereafter, the aqueous sodium hydroxide solution and the remaining water were added, and the mixture was mixed for 15 seconds under reduced pressure conditions at 5,500 rpm with the Ultra Mixer and 120 rpm with the Anchor, and further mixed under reduced pressure conditions at 120 rpm with the Anchor until the temperature reached 35° C., to obtain a topical preparation composition. In the comparative examples, the mixture was mixed in the same manner as in the examples, except that the comparative product (B) was used.

The carboxyvinyl polymer raw material used and the measured values of the critical strain and viscosity are shown below. The amount of each component in the table is the amount converted to a pure content. The critical strain was measured using a 0.4% by mass carboxyvinyl polymer aqueous solution adjusted to pH 7.0 at 25 ° C. Using a stress-controlled cone-plate rheometer AR2000ex (manufactured by TA Instruments Japan Co., Ltd.), a 40 mm aluminum cone plate was used to measure the strain dependency under the conditions of strain: 0.01 to 1,000%, frequency: 1 Hz, and temperature: 25 ° C. The critical strain γcr (the intersection point between the straight line of the storage modulus G' in the range of strain 0.3% to 1% and the straight line G' with strain 80% to 300%) was obtained, which is the value of the strain at the point where the storage modulus G' obtained from the measurement transitions from the linear to the nonlinear region. The viscosity was measured using a 0.2% by mass carboxyvinyl polymer aqueous solution by the method described above.
Sinthalen L (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.): critical strain 39.3%, 0.2% viscosity 4,440 mPa·s. FIG. 1 is a graph showing the measurement results of the critical strain of Sinthalen L.
NTC-CARBOMER 381 (product name, manufactured by Nikko Chemicals Co., Ltd.): critical strain 40.1%, 0.2% viscosity 3,324 mPa s)
AQUEPEC HV-801EG300 (trade name, manufactured by Sumitomo Seika Chemicals Co., Ltd.) (critical strain: 34.5%, 0.2% viscosity 4,311 mPa·s) Comparison product AQUEPEC HV-501E (trade name, manufactured by Sumitomo Seika Chemicals Co., Ltd.): critical strain 33.5%, 0.2% viscosity 4,500 mPa·s Comparison product CARBOPOL 980 NF (trade name, manufactured by Lubrizol): critical strain 19.2%, 0.2% viscosity 20,750 mPa·s Comparison product NTC-CARBOMER380 (trade name, manufactured by Nikko Chemicals Co., Ltd.): critical strain 27.1%, 0.2% viscosity 21,000 mPa·s Comparison product

[evaluation]
(1) Storage Conditions The topical composition was placed in a glass bottle and stored under conditions of 50° C. and 75% RH for up to 2.5 months.
(2) Viscosity of topical composition: Measured using a BH viscometer (Tokyo Keiki), 10 rpm, rotor No. 3, 1 minute, 25°C, and the day after production (after about 24 hours at room temperature).
(3) Storage modulus G′ of topical preparation composition
A stress-controlled cone-plate rheometer AR2000ex (manufactured by TA Instruments Japan, Inc.) with a 40 mm aluminum cone plate was used to measure the strain dependency under the conditions of strain: 0.01 to 1,000%, frequency: 1 Hz, and temperature: 25°C.
(4) Critical strain γ of the topical composition
The strain dependence of the storage modulus G' in the strain range of 0.01 to 1,000% was measured using the above-mentioned equipment and conditions, and the intersection point between the straight line of the storage modulus G' in the strain range of 0.1 to 0.5% and the straight line of G' obtained from the strain range of 100 to 300% was determined.
(5) Emulsion Stability The properties after storage for up to 2.5 months under conditions of 50° C. and 75% RH were confirmed, and the results were evaluated according to the following criteria.
<Evaluation criteria>
5: No separation up to 2.5 months 4: Separation between 2 months and 2.5 months 3: Separation between 1.5 months and 2 months 2: Separation between 1 month and 1.5 months 1: Separation between 0.5 months and 1 month 0: Separation in less than 0.5 months A score of 3 or above is considered a pass.

The raw materials used in the above examples other than component (B) are listed below. Unless otherwise specified, the amount of each component in the table is the pure amount.
Glycerin (product name "Pharmacopoeia Glycerin", manufactured by Sakamoto Pharmaceutical Co., Ltd.), JP-compliant urea (product name "Urea", manufactured by Takasugi Pharmaceutical Co., Ltd.), JP-compliant 1,3-butylene glycol (product name "1,3-butylene glycol", manufactured by Daicel Corporation), JP-compliant propylene glycol (product name "Propylene Glycol", manufactured by ADEKA Corporation), JP-compliant lactic acid (product name "Japanese Pharmacopoeia 90% Lactic acid" manufactured by Showa Kako Co., Ltd.), dipotassium glycyrrhizinate (trade name "dipotassium glycyrrhizinate" manufactured by Maruzen Pharmaceutical Co., Ltd.), glycine (trade name "glycine (aminoacetic acid)" manufactured by Yuki Gosei Yakuhin Kogyo Co., Ltd.), sodium hydroxide (trade name "sodium hydroxide" manufactured by Kosakai Pharmaceutical Co., Ltd.), sodium edetate hydrate (trade name "Clewat N" manufactured by Nagase ChemteX Co., Ltd.), hydrogenated oil (trade name "TRIFAT PS-45H, manufactured by Nippon Surfactant Industry Co., Ltd.), Japanese Pharmacopoeia-compliant isopropyl myristate (trade name "IPM-EX", manufactured by Nippon Surfactant Industry Co., Ltd.), pharmaceutical additive-compliant dimethylpolysiloxane (trade name "KF-96A-6MD", manufactured by Shin-Etsu Chemical Co., Ltd.), pharmaceutical additive-compliant polyethylene glycol monostearate (trade name "MYS-55MV", manufactured by Nippon Surfactant Industry Co., Ltd.), pharmaceutical additive-compliant decaglyceryl pentastearate (trade name "DECAGLYN 5-SV", manufactured by Nikko Chemicals Co., Ltd.), pharmaceutical additive-compliant tocopherol acetate (trade name "Japanese Pharmacopoeia tocopherol acetate", manufactured by Mitsubishi Chemical Foods Co., Ltd.), Japanese Pharmacopoeia-compliant butyl paraoxybenzoate (trade name "Japanese Pharmacopoeia butyl paraoxybenzoate", manufactured by Ueno Pharmaceutical Co., Ltd.), Japanese Pharmacopoeia-compliant

Claims (6)

A topical composition which is an O/W type emulsion containing (A) 30% by mass or more of a water-soluble moisturizing component and (B) a carboxyvinyl polymer, and has a viscosity of 4,000 mPa s or less at 25°C,
The component (B) is a carboxyvinyl polymer having a critical strain of 35.0% or more, which is calculated from the intersection of a straight line representing the storage modulus G' in a strain range of 0.3 to 1% and a straight line representing the storage modulus G' in a strain range of 80 to 300%, when the storage modulus G' is measured in a 0.4% by mass aqueous solution (pH 7.0) at 25°C, a strain range of 0.01 to 1,000%, and a frequency of 1 Hz. The topical composition according to claim 1, wherein component (A) is one or more selected from polyhydric alcohols, sugars, sugar alcohols, and urea. The topical composition according to claim 1 or 2, wherein the content of component (B) is 0.05 to 1 mass %. The topical composition is an O/W type emulsion containing (A) 30% by mass or more of a water-soluble moisturizing component and (B') a carboxyvinyl polymer, and has a viscosity of 4,000 mPa·s or less at 25°C, wherein, when the storage modulus G' is measured at 25°C, in a strain range of 0.01 to 1,000%, and at a frequency of 1 Hz, the critical strain calculated from the intersection point between the straight line representing the storage modulus G' in a strain range of 0.1 to 0.5% and the straight line representing the storage modulus G' in a strain range of 100 to 300% is 20.0% or more. The topical composition according to claim 4, wherein component (A) is one or more selected from polyhydric alcohols, sugars, sugar alcohols, and urea. A method for producing an external preparation composition, which is an O/W type emulsion containing (A) 30% by mass or more of a water-soluble moisturizing component and (B) a carboxyvinyl polymer, and has a viscosity of 4,000 mPa s or less at 25°C, comprising:
the component (B) is a carboxyvinyl polymer having a critical strain of 35.0% or more, calculated from the intersection of a straight line representing the storage modulus G' in a strain range of 0.3 to 1% and a straight line representing the storage modulus G' in a strain range of 80 to 300%, when the storage modulus G' is measured in a 0.4% by mass aqueous solution (pH 7.0) at 25°C, a strain range of 0.01 to 1,000%, and a frequency of 1 Hz;
A method for producing an external preparation composition, comprising the step of mixing the component (A) and the component (B).

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