JP2024114984A - Emulsion composition - Google Patents

Abstract

To provide an emulsion composition containing pyrrolidone carboxylic acid and/or a salt thereof, the emulsion composition having excellent emulsion stability.SOLUTION: An emulsion composition containing pyrrolidone carboxylic acid and/or a salt thereof is blended with ufenamate together with the pyrrolidone carboxylic acid and/or a salt thereof, so that it has excellent emulsion stability.SELECTED DRAWING: None

Description

The present invention relates to an emulsion composition that contains pyrrolidone carboxylic acid and/or a salt thereof and has excellent stability of properties.

Emulsion compositions can be used to blend aqueous and oily ingredients, can be used in a variety of formulations, and have an excellent feel when applied to the skin. For this reason, emulsion compositions are widely used in the fields of topical medicines and cosmetics.

Sodium pyrrolidone carboxylate is an ingredient that is incorporated as a moisturizer in compositions for external use, and is also incorporated into emulsion compositions.

For example, Patent Document 1 describes that an emulsion composition containing α-monoalkyl glyceryl ether, waxes, and a specific silicone oil may contain a moisturizing agent selected from the group consisting of glycerin, fructose, trimethylglycine, sodium lactate, and sodium pyrrolidone carboxylate. Patent Document 2 describes that an emulsion composition containing 0.1 to 10% by mass of a water-soluble polymer obtained by mixing a specific agar and xanthan gum at a specific mass ratio, and 30% by mass or more of water may contain one or more moisturizing agents selected from hyaluronic acid or a salt thereof, pyrrolidone carboxylic acid or a salt thereof, glycerin, diglycerin, and polyglycerin. Patent Document 3 describes that a skin topical composition containing ascorbic acid glucoside, 2-amino-2-hydroxymethyl-1,3-propanediol, and ethylenediaminetetraacetic acid or a salt thereof and having a specific pH can be prepared as an emulsion composition, and pyrrolidone carboxylic acid or a salt thereof may be contained.

WO 97/044001 International Publication No. 2011/111854 JP 2014-129278 A

Although it is described in Patent Documents 1 to 3 that pyrrolidone carboxylic acid or a salt thereof may be blended in the emulsion compositions, the stability of the properties of the emulsion composition when pyrrolidone carboxylic acid or a salt thereof is blended has not actually been examined. The present inventors prepared an emulsion composition blended with pyrrolidone carboxylic acid or a salt thereof, but were faced with the problem that separation occurred after storage, resulting in unstable properties.

The present invention aims to provide an emulsion composition containing pyrrolidone carboxylic acid or a salt thereof, which has excellent emulsion stability.

The inventors conducted extensive research into emulsion compositions containing pyrrolidone carboxylic acid or a salt thereof and unexpectedly discovered that excellent emulsion stability was achieved by incorporating ufenamate, which was not previously known to have an emulsion stabilizing effect. The present invention was completed through further research based on this knowledge.

That is, the present invention provides the following aspects.
Item 1. An emulsion composition containing pyrrolidone carboxylic acid and/or a salt thereof, and ufenamate.
Item 2. The emulsion composition according to Item 1, comprising the pyrrolidone carboxylic acid and/or a salt thereof in a total amount of 0.001 to 10% by weight.
Item 3. The emulsion composition according to Item 1 or 2, wherein the ufenamate is contained in an amount of 1.5 parts by weight or more per part by weight of the total amount of the pyrrolidone carboxylic acid and/or a salt thereof.
Item 4. A method for emulsion stabilization, comprising blending ufenamate together with pyrrolidone carboxylic acid and/or a salt thereof in an emulsion composition containing the pyrrolidone carboxylic acid and/or a salt thereof.

According to the present invention, it is possible to provide an emulsion composition containing pyrrolidone carboxylic acid or a salt thereof with excellent emulsion stability.

The emulsion composition of the present invention is characterized by containing pyrrolidone carboxylic acid and/or a salt thereof, and ufenamate. The emulsion composition of the present invention will be described in detail below.

Pyrrolidone carboxylic acid and/or its salt The pyrrolidone carboxylic acid and/or its salt contained in the emulsion composition of the present invention is a component known as a moisturizing agent. Pyrrolidone carboxylic acid and/or its salt destabilizes the properties of the emulsion composition after storage, but the emulsion composition of the present invention exhibits excellent emulsion stability.

Pyrrolidone carboxylic acid is a component also known as pyroglutamic acid or pidolic acid. There are no particular limitations on the three-dimensional structure of pyrrolidone carboxylic acid, and it may be any of D-pyrrolidone carboxylic acid, L-pyrrolidone carboxylic acid, and DL-pyrrolidone carboxylic acid.

The salt of pyrrolidone carboxylic acid is not particularly limited as long as it is pharma- ceutically or cosmetically acceptable, but examples thereof include alkali metal salts such as sodium salt, potassium salt, and lithium salt; alkaline earth metal salts such as calcium salt and magnesium salt; ammonium salt, alkanolamine salt, and the like. These salts of pyrrolidone carboxylic acid may be used alone or in combination of two or more kinds. Among these pyrrolidone carboxylic acids, alkali metal salts are preferred, and sodium salt is more preferred.

The emulsion composition of the present invention has excellent emulsion stability after storage, and therefore can effectively obtain emulsion stability even in the presence of a larger amount of electrolytes that tend to cause aggregation of emulsion particles.
From this viewpoint, it is even more preferable that the emulsion composition of the present invention contains, among pyrrolidone carboxylic acid and salts of pyrrolidone carboxylic acid, a salt of pyrrolidone carboxylic acid which generates a larger number of electrolytes upon complete ionization.

The content of pyrrolidone carboxylic acid and/or a salt thereof in the emulsion composition of the present invention is not particularly limited and can be appropriately determined depending on the moisturizing property to be imparted, and may be, for example, 0.001 to 10% by weight in terms of the total amount of pyrrolidone carboxylic acid and its salt. From the viewpoint of obtaining more preferable emulsion stability, a preferred example of the content of pyrrolidone carboxylic acid and/or a salt thereof is 0.001 to 5% by weight. Furthermore, since the emulsion composition of the present invention has excellent emulsion stability after storage, even if a relatively large amount of pyrrolidone carboxylic acid and/or a salt thereof is contained, emulsion stability can be effectively obtained. From this viewpoint, a preferred example of the content of pyrrolidone carboxylic acid and/or a salt thereof in the emulsion composition of the present invention is 0.1 to 10% by weight, preferably 1 to 10% by weight, more preferably 2 to 10% by weight.

Ufenamate Ufenamate, which is contained in the emulsion composition of the present invention, is also called butyl flufenamate and is a known component as a poorly water-soluble nonsteroidal anti-inflammatory drug. Although emulsion compositions containing pyrrolidone carboxylic acid and/or a salt thereof are unstable in properties after storage, the emulsion composition of the present invention exhibits excellent emulsion stability by incorporating ufenamate.

The content of ufenamate in the emulsion composition of the present invention is not particularly limited and is appropriately set depending on the emulsion stability to be imparted, but may be, for example, 1 to 20% by weight, preferably 2 to 10% by weight, and more preferably 3 to 7% by weight.

In the emulsion composition of the present invention, the ratio of ufenamate to pyrrolidone carboxylic acid and/or a salt thereof is determined according to the content of each of the above-mentioned components, but from the viewpoint of obtaining even better emulsion stability, the content of ufenamate per 1 part by weight of the total amount of pyrrolidone carboxylic acid and/or a salt thereof is, for example, 1.5 parts by weight or more, preferably 1.8 parts by weight or more, and more preferably 2 parts by weight or more. The upper limit of the range of the content of ufenamate per 1 part by weight of the total amount of pyrrolidone carboxylic acid and/or a salt thereof is not particularly limited, but may be, for example, 40 parts by weight or less, preferably 20 parts by weight or less, more preferably 10 parts by weight or less, and even more preferably 5 parts by weight or less.

Oil The emulsion composition of the present invention contains an oil as a base component of the oil phase. The oil is not particularly limited as long as it is pharma- ceutical or cosmetically acceptable, and examples of the oil include liquid oil, solid oil, higher alcohol, etc. These oils may be used alone or in combination of two or more.

The oil content in the emulsion composition of the present invention may be appropriately set depending on the emulsion type, form, and application of the emulsion composition, but may be, for example, 2 to 60% by weight, preferably 4 to 30% by weight, more preferably 4 to 15% by weight, and even more preferably 6 to 8% by weight.

Among the above oils, the emulsion composition of the present invention preferably contains a liquid oil. A liquid oil is an oil that maintains a liquid form at 25°C. The liquid oil may be any oil that is commonly used in cosmetics and topical medicines, and examples of such oils include fatty acids such as oleic acid and isostearic acid; ester oils such as cetyl ethylhexanoate, ethylhexyl palmitate, octyldodecyl myristate, isopropyl myristate, neopentyl glycol diethylhexanoate, glyceryl tri-2-ethylhexanoate, octyldodecyl oleate, isopropyl myristate, glyceryl triisostearate, and glyceryl di-paramethoxycinnamate-monoethylhexanoate; silicone oils such as dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, and octamethylcyclotetrasiloxane; and liquid hydrocarbon oils such as liquid paraffin, squalene, and squalane.

These liquid oils may be used alone or in combination of two or more.

Among these liquid oils, preferably, ester oil, silicone oil, and liquid hydrocarbon oil are used, and more preferably, octyldodecyl myristate, isopropyl myristate, dimethylpolysiloxane, and liquid paraffin are used. Furthermore, among these liquid oils, from the viewpoint of obtaining even more preferable emulsion stability, preferably, liquid hydrocarbon oil is used, and more preferably, liquid paraffin is used.

When liquid oil is contained in the emulsion stabilizer of the present invention, the content is not particularly limited and may be appropriately set depending on the emulsion type, form, and application of the emulsion composition, but may be, for example, 0.5 to 30% by weight, preferably 1 to 20% by weight, more preferably 3 to 10% by weight, and even more preferably 5 to 8% by weight.

The emulsion composition of the present invention contains water as a base component of the aqueous phase. The content of water in the emulsion composition of the present invention may be appropriately set depending on the emulsion type, form, application, etc. of the emulsion composition, and may be, for example, 30 to 95% by weight, preferably 30 to 90% by weight, more preferably 30 to 80% by weight, and even more preferably 30 to 75% by weight.

In addition, since the emulsion composition of the present invention has excellent emulsion stability that suppresses aqueous phase separation after storage, it is possible to obtain excellent emulsion stability even when the emulsion composition contains a large amount of water, which is inherently more likely to cause aqueous phase separation. In view of such effects of the present invention, a suitable embodiment of the emulsion composition of the present invention is an emulsion composition having a relatively high water content. More specifically, suitable examples of the water content in the emulsion composition of the present invention include, for example, 40 to 95% by weight, preferably 45 to 95% by weight, more preferably 50 to 95% by weight, even more preferably 55 to 95% by weight, and even more preferably 60 to 95% by weight.

The emulsion composition of the present invention contains a surfactant as a component for emulsifying the oil phase and the aqueous phase. The surfactant is not particularly limited as long as it is pharma- ceutical or cosmetically acceptable, and examples thereof include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.

From the viewpoint of obtaining even better emulsion stability, the HLB value of the surfactant may be, for example, 10 to 19, preferably 13 to 17.5, and more preferably 13.5 to 15.5. The HLB value is a value calculated according to the Kawakami method (HLB value = 7 + 11.7 log (sum of formula weights of hydrophilic parts/sum of formula weights of lipophilic parts)).

Among these surfactants, nonionic surfactants are preferred from the viewpoint of obtaining better emulsion stability.

Specific examples of the nonionic surfactant include polyoxyethylene hydrogenated castor oils (e.g., PEG-40 hydrogenated castor oil, PEG-50 hydrogenated castor oil, PEG-60 hydrogenated castor oil, PEG-80 hydrogenated castor oil, and PEG-100 hydrogenated castor oil); sorbitan fatty acid esters (e.g., sorbitan monooleate, sorbitan monoisostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate, sorbitan trioleate, diglycerol sorbitan penta-2-ethylhexyl acid, and diglycerol sorbitan tetra-2-ethylhexyl acid); and glycerin fatty acid esters (e.g., monoglyceryl cottonseed oil fatty acid, glyceryl monoerucate, and the like). glyceryl, glyceryl sesquioleate, glyceryl monostearate (glycerin stearate), α,α'-oleic acid pyroglutamate, glycerin monostearate malate, etc.); propylene glycol fatty acid esters (e.g., propylene glycol monostearate, etc.); glycerin alkyl ether; steareth-2; polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tetraoleate, etc.); polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate , polyoxyethylene sorbitol pentaoleate, polyoxyethylene sorbitol monostearate, etc.); polyoxyethylene glycerin fatty acid esters (e.g., polyoxyethylene glycerin monostearate, polyoxyethylene glycerin monoisostearate, polyoxyethylene glycerin triisostearate, etc.); polyoxyethylene fatty acid esters (e.g., polyoxyethylene monooleate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monodioleate, ethylene glycol distearate, etc.); polyoxyethylene alkyl ethers (e.g., polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene glycerin triisostearate, etc.); polyoxyethylene stearyl ether, polyoxyethylene behenyl ether, polyoxyethylene 2-octyldodecyl ether, polyoxyethylene cholestanol ether, etc.); Pluronic (registered trademark) types (for example, Pluronic (registered trademark), etc.); polyoxyethylene-polyoxypropylene alkyl ethers (for example, polyoxyethylene-polyoxypropylene cetyl ether, polyoxyethylene-polyoxypropylene-2-decyltetradecyl ether, polyoxyethylene-polyoxypropylene monobutyl ether, polyoxyethylene-polyoxypropylene hydrogenated lanolin, polyoxyethylene-polyoxypropylene glycerin ether, etc.); steareth-21, etc.

These surfactants may be used alone or in combination of two or more.

Among these nonionic surfactants, from the viewpoint of obtaining better emulsion stability, preferred are polyoxyethylene hydrogenated castor oils, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene fatty acid esters, more preferred are PEG-60 hydrogenated castor oil, polyoxyethylene sorbitan monostearate, and polyoxyethylene monostearate. Furthermore, among these nonionic surfactants, from the viewpoint of obtaining even better emulsion stability, preferred are polyoxyethylene sorbitan fatty acid esters, more preferred are polyoxyethylene sorbitan monostearate.

In the emulsion composition of the present invention, the content of the surfactant may be appropriately set depending on the type of surfactant used, etc., but may be, for example, 0.5 to 7% by weight, preferably 1 to 5% by weight, more preferably 2 to 5% by weight, and even more preferably 3 to 5% by weight.

Other Components In addition to the components described above, the emulsion composition of the present invention may contain other commonly used additives as necessary. Examples of such additives include polyhydric alcohols, thickeners, pH regulators, buffers, solubilizers, chelating agents, preservatives, antioxidants, stabilizers, fragrances, colorants, etc.

The polyhydric alcohol is not particularly limited as long as it is pharma- ceutically or cosmetically acceptable, and examples thereof include dihydric alcohols such as propylene glycol, 1,3-butylene glycol, ethylene glycol, isoprene glycol, diethylene glycol, and dipropylene glycol; trihydric alcohols such as glycerin; and polyethylene glycols such as Macrogol 4000 and Macrogol 6000. These polyhydric alcohols may be used alone or in combination of two or more. Among these polyhydric alcohols, from the viewpoint of obtaining better emulsion stability, dihydric alcohols and trihydric alcohols are preferred, and 1,3-butylene glycol and glycerin are more preferred.

When the emulsion composition of the present invention contains a polyhydric alcohol, its content may be appropriately set depending on the type of polyhydric alcohol used, and may be, for example, 1 to 20% by weight, preferably 5 to 18% by weight, and more preferably 10 to 16% by weight.

The thickener is not particularly limited as long as it is pharma- ceutical or cosmetically acceptable, and examples thereof include carboxyvinyl polymer, hypromellose, polyvinylpyrrolidone, sodium alginate, ethyl cellulose, sodium carboxymethylcellulose, xanthan gum, carrageenan, etc. Among these thickeners, xanthan gum is preferred from the viewpoint of obtaining better emulsion stability. In addition, among these thickeners, carboxyvinyl polymer undergoes an extreme viscosity reduction in the presence of pyrrolidone carboxylic acid and/or a salt thereof, and therefore, when incorporated into a normal emulsion composition containing pyrrolidone carboxylic acid and/or a salt thereof, the storage stability is significantly reduced. However, since the emulsion composition of the present invention has excellent emulsion stability after storage, it is possible to effectively obtain emulsion stability even if the emulsion composition contains a carboxyvinyl polymer. In view of such effects of the present invention, it is preferable that the emulsion composition of the present invention contains at least a carboxyvinyl polymer as a thickener.

When the emulsion composition of the present invention contains a thickener, the content of the thickener may be appropriately set depending on the type of thickener used, but from the viewpoint of obtaining better emulsion stability, the content may be, for example, 0.1 to 2% by weight, preferably 0.1 to 1.8% by weight, more preferably 0.2 to 1.5% by weight, even more preferably 0.3 to 1% by weight, and even more preferably 0.3 to 0.6% by weight. When the emulsion composition of the present invention contains a carboxyvinyl polymer, the content of the carboxyvinyl polymer may be, for example, 0.1 to 1% by weight, preferably 0.3 to 0.5% by weight, and more preferably 0.35 to 0.45% by weight. The ratio of the carboxyvinyl polymer to pyrrolidone carboxylic acid and/or a salt thereof is determined depending on the content of each of the above-mentioned components, and the content of the carboxyvinyl polymer per 1 part by weight of the total amount of pyrrolidone carboxylic acid and/or a salt thereof may be, for example, 0.01 to 0.5 parts by weight, preferably 0.03 to 0.3 parts by weight, and more preferably 0.06 to 0.2 parts by weight.

Furthermore, in addition to the above-mentioned components, the emulsion composition of the present invention may contain, as necessary, medicinal components capable of exerting pharmaceutical or cosmetic physiological functions. Examples of such medicinal components include steroids (dexamethasone, dexamethasone hydrochloride, dexamethasone acetate, hydrocortisone hydrochloride, prednisolone valerate, prednisolone acetate, etc.), antihistamines (diphenhydramine, diphenhydramine hydrochloride, chlorpheniramine maleate, etc.), local anesthetics (lidocaine, dibucaine, procaine, tetracaine, bupivacaine, mepivacaine, chloroprocaine, proparacaine, meprylcaine, or salts thereof), alkyl benzoates (e.g., ethyl aminobenzoate, diethylaminoethyl p-butylaminobenzoate hydrochloride), orthocaine, oxethazaine, oxypolyethyleneoxydecane, scolymus extract, percaminepase, tesit decitin, etc.), anti-inflammatory agents (arabic acid, benzoic ... anthoin, salicylic acid, glycol salicylate, methyl salicylate, indomethacin, felbinac, diclofenac sodium, loxoprofen sodium, etc.), bactericides (benzalkonium chloride, dequalinium chloride, benzethonium chloride, cetylpyridinium chloride, chlorhexidine hydrochloride, chlorhexidine gluconate, aqueous ammonia, sulfadiazine, lactic acid, phenol, etc.), antipruritic agents (crotamiton, thianthol, etc.), skin protectants (collodion, castor oil, etc.), blood circulation promoting components (vanillylamide nonylate, benzyl nicotinate, capsaicin, capsicum extract, etc.), vitamins (vitamins A, B, C, D, E, etc.), mucopolysaccharides (sodium chondroitin sulfate, glucosamine, hyaluronic acid, etc.), etc. These medicinal components may be used alone or in combination of two or more. Furthermore, when these medicinal ingredients are contained in the emulsion composition of the present invention, the content may be appropriately set depending on the type of medicinal ingredient used, the expected effect, etc.

Formulation and Use The emulsion type of the emulsion composition of the present invention may be either a water-in-oil type or an oil-in-water type.
The emulsion composition of the present invention exhibits excellent emulsion stability that suppresses separation after storage, so that even if the emulsion composition contains a large amount of water, such as an oil-in-water type emulsion that is inherently more prone to aqueous phase separation, it can be provided with excellent emulsion stability. In view of such effects of the present invention, the preferred emulsion type of the emulsion composition of the present invention is an oil-in-water type emulsion that contains a relatively large amount of water.

The emulsion composition of the present invention can be used as an external preparation such as a cosmetic, an external quasi-drug, or an external medicine. The product form of the emulsion composition of the present invention is not particularly limited, and examples thereof include creams, ointments, emulsions, gels, oils, lotions, liniments, and aerosols. Of these, creams, ointments, emulsions, and lotions are preferred, and creams, emulsions, and lotions are more preferred.

The emulsion composition of the present invention can be manufactured according to the formulation method of known emulsion preparations depending on the emulsion type.For example, the method of manufacturing the emulsion composition of the present invention includes a method of dividing the components to be contained into water-soluble components and oily components, preparing an aqueous phase containing the water-soluble components and an oily phase containing the oily components, and emulsifying them according to a known method.

As described above, ufenamate exerts excellent emulsion stability in an emulsion composition containing pyrrolidone carboxylic acid and/or a salt thereof. Therefore, the present invention further provides a method for emulsion stabilization , which comprises blending ufenamate together with pyrrolidone carboxylic acid and/or a salt thereof in an emulsion composition containing pyrrolidone carboxylic acid and/or a salt thereof.

In the emulsion stabilization method of the present invention, emulsion stabilization refers to suppressing separation of the emulsion composition after storage. Separation refers to separation of the aqueous phase and/or oil phase from the emulsion composition. A more preferred aspect of emulsion stabilization is suppressing separation of the aqueous phase from the emulsion composition after storage, and a more preferred aspect is maintaining the emulsion state of the emulsion composition uniform after storage, that is, maintaining a state in which the droplets in the emulsion are uniformly dispersed in the dispersion medium.

In the emulsion stabilization method of the present invention, the type and content of each component used, the type and content of components blended in the emulsion composition, and the formulation form are the same as those in "1. Emulsion composition" above.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these.

Test Examples The emulsion compositions shown in Tables 1 and 2 were prepared. Specifically, component (B) was added to a mixture of each component (I) and dissolved at 70 to 80°C to prepare an oil phase. Meanwhile, a mixture of each component (II) was dissolved at 75 to 85°C, and a 50% by weight aqueous solution of component (A) was added to prepare an aqueous phase. A water phase heated to 70 to 80°C was added to an oil phase heated to 70 to 80°C, emulsified by stirring using a homomixer, and cooled to 35°C. In this way, an emulsion composition (emulsion; oil-in-water type) was produced.

10 g of each of the obtained emulsion compositions was filled into a 15 mL transparent plastic tube, sealed, and centrifuged at 3,000 rpm for 10 minutes using a centrifuge. After centrifugation, each emulsion composition was visually observed and evaluated for emulsion stability based on the following criteria. The results are shown in Tables 1 and 2.
--: Phase separation was clearly observed, and the degree of turbidity of the aqueous phase was low.
-: Phase separation was clearly observed, and the water phase was significantly turbid.
+: No phase separation was observed, and only a creaming tendency was observed.
++: No phase separation observed, slight creaming tendency observed only at the bottom tip of the tube.
+++: No phase separation was observed and the emulsion was uniform.
The creaming tendency refers to a non-uniform emulsified state, specifically, a state in which droplets in the generated emulsion are in the process of floating up or sinking down due to the difference in specific gravity with the dispersion medium.

As is clear from Table 2, the emulsion state was stable in the emulsion composition not containing sodium pyrrolidone carboxylate (Reference Example), but the emulsion state was unstable in the emulsion composition containing sodium pyrrolidone carboxylate (Comparative Examples 1 and 2). In contrast, as is clear from Table 1, the emulsion state was stabilized by further blending ufenamate with the emulsion composition containing sodium pyrrolidone carboxylate (Examples 1 to 7). This effect of improving emulsion stability was particularly noticeable in Examples 1 and 4 to 7.

Formulation Examples Emulsion compositions (oil-in-water type) were prepared according to the formulations shown in Tables 3 and 4. All of the emulsion compositions had excellent emulsion stability.

Claims (4)

An emulsion composition containing pyrrolidone carboxylic acid and/or a salt thereof, and ufenamate. The emulsion composition according to claim 1, containing 0.001 to 10% by weight of the pyrrolidone carboxylic acid and/or its salt in total. The emulsion composition according to claim 1 or 2, wherein the ufenamate is contained in an amount of 1.5 parts by weight or more per part by weight of the total amount of the pyrrolidone carboxylic acid and/or its salt. An emulsion stabilization method in which ufenamate is blended with pyrrolidone carboxylic acid and/or a salt thereof in an emulsion composition containing the pyrrolidone carboxylic acid and/or a salt thereof.