JP7500193B2 - Emulsion composition - Google Patents

Description

The present invention relates to an emulsion composition. More specifically, the present invention relates to an emulsion composition with improved usability.

Active ingredients are blended in topical compositions in the hope of achieving various efficacies. It is known that the distribution of active ingredients blended in topical compositions (to the stratum corneum) is greatly affected by the "affinity between the base and the skin" (how easily the base blends with the skin) and the "affinity between the base and the drug" (how easily the drug dissolves in the base) (Non-Patent Document 1), and topical compositions are designed with these balances in mind. For example, in the case of a fat-soluble drug, it is known that the use of an oily base improves "percutaneous absorption due to the affinity between the base and the skin" but decreases "percutaneous absorption due to the affinity between the base and the drug," and that the use of a water-soluble base decreases "percutaneous absorption due to the affinity between the base and the skin," but improves "percutaneous absorption due to the affinity between the base and the drug."

Therefore, when a fat-soluble active ingredient is to be incorporated into a composition for external use, it is desirable to incorporate it into an emulsion composition that uses both an oily base and a water-soluble base in order to improve both "percutaneous absorption due to the affinity between the base and the skin" and "percutaneous absorption due to the affinity between the base and the drug."

In addition, it is essential for emulsion compositions to stabilize the emulsified state in order to obtain good efficacy and usability. For example, thickeners are effective in improving both usability and stability, as they suppress creaming by increasing the viscosity when left to stand (Patent Document 1). For example, it is known that the emulsion stability can be further improved by blending thickeners such as carboxyvinyl polymer (carbomer), cationized hyaluronic acid, xanthan gum, alginate, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, gellan gum, and guar gum in oil-in-water emulsion compositions (Patent Document 2).

Edited by Michiteru Otani, "Tidbits on Ointments vol.1", [online], Maruho Co., Ltd., [Retrieved December 10, 2019], Internet <URL: https://www.maruho.co.jp/medical/pharmacist/infostore/vol01/05.html>

JP 2001-039827 A JP 2018-197210 A

An emulsion composition containing a fat-soluble active ingredient is a formulation that should, in theory, be able to improve the feeling of use by combining an oily base (hereinafter referred to as an "oil base") with a water-soluble base; however, since an oily base is essential, it is thought that the oily base causes problems such as poor compatibility with the skin and stickiness. On the other hand, there is an increasing demand for topical compositions with an even better feeling of use, and an emulsion composition with an improved feeling of use is desired. To achieve this, it is necessary to have even better emulsion stability as a prerequisite.

The inventor first investigated the properties of emulsion compositions containing fat-soluble active ingredients and found that not only was the emulsion stability extremely poor, but that in some cases the emulsion composition could not even be formed. In order to improve emulsion stability, a thickener such as hydroxyethyl cellulose or sodium alginate was added to a composition containing an oil phase and an aqueous phase containing fat-soluble active ingredients, together with a surfactant. However, the addition of these thickeners did little to improve the emulsion state, and the inventor was faced with the problem that in some cases the emulsion composition still could not even be formed.

The present invention aims to provide a formulation technology that improves the emulsion stability and usability of a composition containing a fat-soluble active ingredient.

After extensive research, the inventors discovered that an emulsion composition containing a fat-soluble active ingredient can be made with a nonionic surfactant and by incorporating a polymer whose constituent unit is 2-methacryloyloxyethyl phosphorylcholine and carboxymethylcellulose, it is possible to obtain an emulsion composition with excellent emulsion stability and usability. 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 comprising (A) a fat-soluble active ingredient, (B) an oily base, (C) a nonionic surfactant, (D) water, (E) a phosphocholine group-containing polymer, and (F) carboxymethylcellulose and/or a salt thereof.
Item 2. The emulsion composition according to Item 1, wherein the content of the component (B) is 0.5 to 4% by weight.
Item 3. The emulsion composition according to Item 1 or 2, wherein the component (B) contains a solid oily base.
Item 4. The emulsion composition according to any one of Items 1 to 3, wherein the content of the component (E) is 0.1 to 1% by weight.
Item 5. The emulsion composition according to any one of Items 1 to 4, wherein the content of the component (F) is 0.1 to 10% by weight.
Item 6. The emulsion composition according to any one of Items 1 to 5, comprising 0.1 to 3 parts by weight of the (F) component per 1 part by weight of the (B) component.

The emulsion composition of the present invention has excellent emulsion stability, and improves the feel when used by eliminating the stickiness and poor skin compatibility caused by oily bases.

The emulsion composition of the present invention is characterized by containing (A) a fat-soluble active ingredient (hereinafter also referred to as "component (A)"), (B) an oily base (hereinafter also referred to as "component (B)"), (C) a nonionic surfactant (hereinafter also referred to as "component (C)"), (D) water (hereinafter also referred to as "component (D)"), (E) a phosphocholine group-containing polymer (hereinafter also referred to as "component (E)"), and (F) carboxymethylcellulose and/or a salt thereof (hereinafter also referred to as "component (F)"). The emulsion composition of the present invention will be described in detail below.

The emulsion composition of the present invention contains a fat-soluble active ingredient as component (A). As the fat-soluble active ingredient, those that are incorporated into compositions for external use can be used without any particular limitation.

Examples of fat-soluble active ingredients used in the present invention include non-steroidal anti-inflammatory agents (ufenamate, diclofenac, ibuprofen, etc.), fat-soluble vitamins (retinol and its derivatives (vitamin A), tocopherol and its derivatives (vitamin E), vitamin D, vitamin K, etc.), steroidal anti-inflammatory agents (dexamethasone, betamethasone, prednisolone, etc.), antibacterial agents (clarithromycin, ofloxacin), antiviral agents (chloramphenicol, acyclovir, etc.), immunosuppressants (cyclosporine, tacrolimus, paclitaxel, etc.), local anesthetics (lidocaine, etc.), vasoconstrictors (epinephrine, etc.), etc. These fat-soluble active ingredients may be used alone or in combination of two or more. Among these fat-soluble active ingredients, non-steroidal anti-inflammatory agents are preferred, and ufenamate is more preferred.

The content of component (A) in the emulsion composition of the present invention is not particularly limited and can be set appropriately depending on the efficacy to be imparted. Specifically, the content of component (A) is, for example, 1 to 10% by weight, preferably 3 to 10% by weight, and more preferably 4 to 6% by weight.

The emulsion composition of the present invention contains an oily base as component ( B). An oily base causes poor skin compatibility and sticky feeling in the use of a topical composition, but the emulsion composition of the present invention can improve the use feeling caused by the oily base.

The oil base includes (B1) solid oil (hereinafter also referred to as "component (B1)"), (B2) semi-solid oil (hereinafter also referred to as "component (B2)"), and (B3) liquid oil (hereinafter also referred to as "component (B3)"). In the oil-based topical composition of the present invention, any one of components (B1), (B2) and (B3) may be used as component (B), or two or more of them may be used in combination.

The oily base causes poor skin compatibility and sticky feeling when using a topical composition, in the order of (B3), (B2), and (B1). Therefore, in the emulsion composition of the present invention, from the viewpoint of further enhancing the effect of improving the feeling of use, it is preferable that the (B) component contains at least the (B3) component.

In addition, since the emulsion composition of the present invention has an excellent effect of improving the feeling of use, even if the topical composition contains the component (B1), which is particularly poorly compatible with the skin and sticky when used, the emulsion composition of the present invention can effectively improve the feeling of use. From this perspective, a preferred example of the present invention is one in which the component (B) contains at least the component (B1). Furthermore, the emulsion composition of the present invention can be easily prepared by using a self-emulsifying wax, which is a mixture of the component (B1) and at least a part of the component (C). From this perspective, it is also preferable that the component (B) contains the component (B1).

The solid oil of component (B1) is an oil that maintains a solid form at 25°C. The solid oil used in the present invention may be any oil that is normally used in cosmetics and topical medicines, and examples of such solid oils include higher alcohols such as monohydric alcohols having 14 to 34 carbon atoms (e.g., myristyl alcohol, cetyl alcohol, stearyl alcohol, isostearyl alcohol, behenyl alcohol, hexadecyl alcohol, and lanolin alcohol); petroleum waxes such as microcrystalline wax; vegetable waxes such as carnauba wax, candelilla wax, rice wax, and wood wax; animal waxes such as beeswax and whale wax; synthetic waxes such as silicone wax and polyethylene wax; and fatty acids. These solid oils may be used alone or in combination of two or more. Among these solid oils, higher alcohols are preferred, monohydric alcohols having 18 to 34 carbon atoms are more preferred, cetyl alcohol and stearyl alcohol are even more preferred, and stearyl alcohol is even more preferred.

The semi-solid oil of component (B2) is an oil that maintains a semi-solid (viscous and freely deformable) form at 25°C. The semi-solid oil used in the present invention may be any oil that is normally used in cosmetics and topical medicines, and examples of such oils include paste-like hydrocarbons such as petrolatum; lanolin, dimer acid esters, dimer diol derivatives, cholesterol fatty acid esters, phytosterol fatty acid esters, polyglycerin fatty acid esters, and pentaerythritol fatty acid esters. These semi-solid oils may be used alone or in combination of two or more.

The liquid oil of component (B3) is an oil that maintains a liquid form at 25°C. The liquid oil used in the present invention may be any oil that is normally used in cosmetics and topical medicines, and may be, for example, liquid hydrocarbon oils such as liquid paraffin, squalene, and squalane; silicone oils such as dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, and octamethylcyclotetrasiloxane; triglycerides of fatty acids having 6 to 12 carbon atoms (for example, avocado oil, camellia oil, macadamia nut oil, olive oil, jojoba oil, soybean oil, cottonseed oil, rapeseed oil, sesame oil, safflower oil, corn oil, Examples of the liquid oil include vegetable oils such as peanut oil, coconut oil, perilla oil, and castor oil; synthetic oils such as 2-linoleoyl-1,3-dioctanoylglycerol; and ester oils such as cetyl ethylhexanoate, ethylhexyl palmitate, octyldodecyl myristate, neopentyl glycol diethylhexanoate, glyceryl tri-2-ethylhexanoate, octyldodecyl oleate, isopropyl myristate, glyceryl triisostearate, and glyceryl divaleroxycinnamate-monoethylhexanoate. These liquid oils may be used alone or in combination of two or more. Among these liquid oils, preferred are liquid hydrocarbon oils, silicone oils, and medium-chain fatty acid triglycerides.

The content of the (B) component in the emulsion composition of the present invention is not particularly limited and can be appropriately set depending on the formulation form, etc. Specifically, the content of the (B) component can be, for example, 0.5 to 4% by weight. From the viewpoint of further enhancing the effect of improving emulsion stability and usability, the content of the (B) component is preferably 0.5 to 3% by weight, more preferably 0.5 to 2% by weight, and even more preferably 0.5% by weight or more and less than 1.8% by weight. In addition, since the emulsion composition of the present invention has an excellent effect of improving usability, even if the emulsion composition contains a relatively large amount of the (B) component, the effect of improving usability can be effectively obtained. From this viewpoint, a suitable example of the content of the (B) component is preferably 0.8 to 4% by weight, more preferably 1.1 to 4% by weight, and even more preferably more than 1.3% by weight and 4% by weight or less.

When the (B1) component is included as the (B) component, the amount of the (B1) component in the oil-based topical composition of the present invention is, for example, more than 0% by weight and not more than 1% by weight, preferably more than 0% by weight and not more than 0.8% by weight, and more preferably more than 0% by weight and less than 0.5% by weight.

When the (B1) component is included as the (B) component, the content of the (B1) component relative to 100 parts by weight of the (B) component is, for example, more than 0 parts by weight and not more than 80 parts by weight, preferably more than 0 parts by weight and not more than 60 parts by weight, more preferably more than 0 parts by weight and not more than 50 parts by weight, and even more preferably more than 0 parts by weight and not more than 39 parts by weight.

When component (B3) is included as component (B), the amount of component (B3) in the oil-based topical composition of the present invention is, for example, 0.5 to 3% by weight, preferably 0.8 to 2% by weight, and more preferably 1 to 1.5% by weight.

When the (B3) component is included as the (B) component, the content of the (B3) component relative to 100 parts by weight of the (B) component is, for example, 35 parts by weight or more and less than 100 parts by weight, preferably 50 parts by weight or more and less than 100 parts by weight, more preferably 60 parts by weight or more and less than 100 parts by weight, and even more preferably 72 parts by weight or more and less than 100 parts by weight.

Furthermore, when the (B) component contains the (B1) component and the (B3) component, the ratio of the (B1) component and the (B3) component is determined by the above-mentioned content of each component, but preferably, the content of the (B1) component per 1 part by weight of the (B3) component is more than 0 parts by weight and not more than 1 part by weight, preferably more than 0 parts by weight and not more than 0.5 parts by weight, and more preferably more than 0 parts by weight and not more than 0.39 parts by weight.

(C) Nonionic surfactant The emulsion composition of the present invention contains a nonionic surfactant as component (C). Examples of the nonionic surfactant include lipophilic nonionic surfactants and hydrophilic nonionic surfactants. As the nonionic surfactant, either or both of the lipophilic nonionic surfactant and the hydrophilic nonionic surfactant may be used, but from the viewpoint of further enhancing the effect of improving emulsion stability and usability, preferably, the hydrophilic nonionic surfactant is used.

Examples of hydrophilic nonionic surfactants include polyoxyethylene (hereinafter abbreviated as POE) fatty acid esters such as POE monolaurate, POE monostearate, and POE monooleate; POE sorbitan fatty acid esters such as POE sorbitan monolaurate, POE sorbitan monostearate, and POE sorbitan monooleate; POE sorbitan fatty acid esters such as POE sorbitan monooleate; POE glycerin fatty acid esters such as POE glycerin monoisostearate; POE alkyl ethers such as POE stearyl ether; POE alkyl phenyl ethers such as POE nonylphenyl ether; POE aralkyl ethers; POE behenyl ether; Examples of the hydrophilic nonionic surfactants include POE alkenyl ethers such as POE ether, Pluronic type surfactants such as Pluronic, POE-polyoxypropylene (hereinafter abbreviated as POP) cetyl ether, POE-POP alkyl ethers such as POE-polyoxypropylene (hereinafter abbreviated as POP) cetyl ether, tetraPOE-tetraPOP ethylenediamine condensates such as Tetronic, POE castor oil, POE castor oil-hydrogenated castor oil derivatives such as POE castor oil and POE hydrogenated castor oil, POE beeswax-lanolin derivatives, alkanolamides, POE propylene glycol fatty acid esters, POE alkylamines, POE fatty acid amides, sucrose fatty acid esters, POE nonylphenyl formaldehyde condensates, alkylethoxydimethylamine oxides, trioleyl phosphates, etc. These hydrophilic nonionic surfactants may be used alone or in combination of two or more. Among these hydrophilic nonionic surfactants, preferred are POE aralkyl ether, POE alkenyl ether, and POE castor oil hydrogenated castor oil derivatives, and more preferred are POE aralkyl ether, POE behenyl ether, and POE hydrogenated castor oil.

The emulsion composition of the present invention can be easily prepared by using a self-emulsifying wax that is a mixture of component (B1) and at least a portion of component (C). The combination of component (B1) and at least a portion of component (C) that constitutes such a self-emulsifying wax is not particularly limited, but preferred examples include a combination of stearyl alcohol and POE aralkyl ether, a combination of cetanol and POE fatty acid ester (particularly POE monostearate), and the like, and more preferably a combination of stearyl alcohol and POE aralkyl ether.

The content of component (C) in the emulsion composition of the present invention is not particularly limited and can be set appropriately depending on the formulation form, etc., but examples include 1 to 5% by weight, preferably 2 to 4.5% by weight, more preferably 3 to 4.3% by weight, and even more preferably more than 3.5% by weight and less than 4% by weight.

The emulsion composition of the present invention contains water as component (D ). The content of component (D) in the emulsion composition of the present invention is not particularly limited and is appropriately set depending on the formulation form, etc., but may be, for example, 60 to 98% by weight, preferably 70 to 95% by weight, more preferably 75 to 90% by weight, and even more preferably 80 to 85% by weight.

(E) Phosphocholine group-containing polymer The emulsion composition of the present invention contains a phosphocholine group-containing polymer as the component (E). An emulsion composition containing a fat-soluble active ingredient has a poor feeling of use such as stickiness and/or poor compatibility due to an oily base, but the emulsion composition of the present invention can obtain an excellent effect of improving the feeling of use by blending the component (E) together with the component (F) in the emulsion composition containing a fat-soluble active ingredient.

A phosphocholine group-containing polymer is a polymer formed by polymerizing a monomer containing a phosphocholine group (hereinafter, sometimes referred to as a "phosphocholine group-containing monomer"), and is a known component that has moisturizing properties, etc.

In the phosphocholine group-containing polymer, the type of phosphocholine group-containing monomer is not particularly limited, but specific examples include 2-methacryloyloxyethyl phosphorylcholine, 2-methacryloyloxyethyl phosphorylethanolamine, and the like. In the phosphocholine group-containing polymer, the phosphocholine group-containing monomer may be contained alone or in combination of two or more types. Among these phosphocholine group-containing monomers, 2-methacryloyloxyethyl phosphorylcholine is preferred from the viewpoint of further enhancing the effect of improving emulsion stability and usability.

The phosphocholine group-containing polymer used in the present invention may be a homopolymer consisting of one type of phosphocholine group-containing monomer, or a copolymer consisting of two or more types of monomers.

When the phosphocholine group-containing polymer is a copolymer, it may be a copolymer consisting of two or more kinds of phosphocholine group-containing monomers, or it may be a copolymer consisting of at least one kind of phosphocholine group-containing monomer and at least one kind of monomer other than the phosphocholine group-containing monomer.

The type of monomer other than the phosphocholine group-containing monomer contained in the phosphocholine group-containing polymer is not particularly limited, provided that it is pharma- ceutical acceptable and capable of radical polymerization with the phosphocholine group-containing monomer, but examples of such monomers include monomers having a vinyl group. Specific examples of monomers other than the phosphocholine group-containing monomer include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, polypropylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, polypropylene glycol polyethylene glycol mono(meth)acrylate, sodium methacrylate, and 2-hydroxy-3-methacryloyloxypropyltrimethylammonium. In the phosphocholine group-containing polymer, the monomers other than the phosphocholine group-containing monomer may be contained alone or in combination of two or more. Among these monomers other than the phosphocholine group-containing monomer, from the viewpoint of further enhancing the effect of improving emulsion stability and usability, preferred are alkyl (meth)acrylates and 2-hydroxy-3-methacryloyloxypropyltrimethylammonium, more preferred are alkyl (meth)acrylates having an alkyl group with 1 to 18 carbon atoms, even more preferred are alkyl (meth)acrylates having an alkyl group with 3 to 5 carbon atoms, and particularly preferred are butyl (meth)acrylates. In this specification, "(meth)acrylate" refers to methacrylate and/or acrylate.

Specific examples of the phosphocholine group-containing polymer used in the present invention include polymethacryloyloxyethyl phosphorylcholine homopolymer, 2-methacryloyloxyethyl phosphorylcholine/butyl methacrylate copolymer (Polyquaternium-51), 2-methacryloyloxyethylene phosphorylcholine/butyl methacrylate/sodium methacrylate copolymer (Polyquaternium-65), 2-methacryloyloxyethyl phosphorylcholine/2-hydroxy-3-methacryloyloxypropyltrimethylammonium copolymer (Polyquaternium-64), 2-methacryloyloxyethyl phosphorylcholine/stearyl methacrylate copolymer (Polyquaternium-61), etc. In the above notation regarding the phosphocholine group-containing polymer, the name in parentheses indicates the cosmetic ingredient name.

In the emulsion composition of the present invention, one type of phosphocholine group-containing polymer may be used as component (E), or two or more types of phosphocholine group-containing polymers may be used in combination.

Among these (E) components, from the viewpoint of further enhancing the effect of improving emulsion stability and usability, preferred are 2-methacryloyloxyethyl phosphorylcholine/butyl methacrylate copolymer, polymethacryloyloxyethyl phosphorylcholine homopolymer, 2-methacryloyloxyethyl phosphorylcholine/2-hydroxy-3-methacryloyloxypropyltrimethylammonium copolymer; more preferred are 2-methacryloyloxyethyl phosphorylcholine/butyl methacrylate copolymer, 2-methacryloyloxyethyl phosphorylcholine/2-hydroxy-3-methacryloyloxypropyltrimethylammonium copolymer; and particularly preferred are 2-methacryloyloxyethyl phosphorylcholine/butyl methacrylate copolymer.

In the emulsion composition of the present invention, the content of component (E) is not particularly limited, but may be, for example, 0.1 to 1% by weight. From the viewpoint of further enhancing the effect of improving emulsion stability and usability, the content of component (E) is preferably 0.14 to 0.7% by weight, more preferably 0.18 to 0.4% by weight, and even more preferably 0.2 to 0.3% by weight.

In the emulsion composition of the present invention, the ratio of the (B) component to the (E) component is determined by the content of each of the above components, and may be, for example, 0.05 to 0.7 parts by weight of the (E) component per part by weight of the (B) component. From the viewpoint of further enhancing the effect of improving emulsion stability and usability, the content of the (E) component per part by weight of the (B) component is preferably 0.08 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight, and even more preferably more than 0.14 parts by weight and less than 0.19 parts by weight.

(F) Carboxymethylcellulose and/or a salt thereof The emulsion composition of the present invention contains carboxymethylcellulose and/or a salt thereof as the component (F). An emulsion composition containing a fat-soluble active ingredient has a poor feeling of use such as stickiness and/or poor compatibility due to an oily base, and other thickeners have a significantly improved emulsion stability compared to an emulsion composition containing a fat-soluble active ingredient. However, the emulsion composition of the present invention can obtain excellent emulsion stability and improved feeling of use by adding the component (F) together with the component (E) to an emulsion composition containing a fat-soluble active ingredient.

Examples of salts of carboxymethylcellulose include alkali metal salts such as sodium salts and potassium salts, and alkaline earth metal salts such as calcium salts, preferably alkali metal salts, and more preferably sodium salts.

In the emulsion composition of the present invention, it is preferable to include a salt of carboxymethylcellulose among the components (F) in order to further enhance the effect of improving emulsion stability and usability.

The content of component (F) in the emulsion composition of the present invention is not particularly limited, but may be, for example, 0.1 to 10% by weight. From the viewpoint of further enhancing the effect of improving emulsion stability and usability, the content of component (F) is preferably 0.4 to 7% by weight, more preferably 0.8 to 4% by weight, even more preferably 1 to 3% by weight, and even more preferably 1 to 2% by weight.

In the emulsion composition of the present invention, the ratio of component (B) to component (F) is determined by the content of each of the above components, and may be, for example, 0.1 to 3 parts by weight of component (F) per part by weight of component (B). From the viewpoint of further enhancing the effect of improving emulsion stability and usability, the content of component (F) per part by weight of component (B) is preferably 0.2 to 2.5 parts by weight, more preferably 0.4 to 2 parts by weight, and even more preferably 0.5 to 1.4 parts by weight.

The emulsion composition of the present invention may contain medicinal ingredients other than the above-mentioned ingredients, if necessary, within the scope of not impairing the effects of the present invention. Examples of such medicinal ingredients include anti-inflammatory agents, anti-aging agents, astringents, antioxidants, moisturizing agents, blood circulation promoters, antibacterial agents, bactericides, drying agents, cooling agents, warming agents, vitamins, amino acids, wound healing promoters, irritation mitigators, analgesics, cell activators, enzyme components, herbal medicine components, etc.

In addition, the emulsion composition of the present invention may contain additives such as other surfactants (anionic surfactants, cationic surfactants, amphoteric surfactants), thickeners, other aqueous bases (lower monohydric alcohols such as ethanol and isopropanol; polyhydric alcohols such as glycerin, propylene glycol, dipropylene glycol, and 1,3-butylene glycol), buffers, chelating agents, antioxidants, stabilizers, preservatives, fragrances, refreshing agents, colorants, dispersants, fluidizing agents, and wetting agents, in addition to the above-mentioned components, as necessary, within the scope of not impairing the effects of the present invention. Among these additives, from the viewpoint of further enhancing the effect of improving emulsion stability and usability, other surfactants and polyhydric alcohols are preferable, and anionic surfactants, glycerin, and 1,3-butylene glycol are more preferable.

Anionic surfactants include anionic surfactants having a phosphate group, a carboxyl group, or a sulfate group.

Examples of anionic surfactants having a phosphate group include polyoxyethylene (POE) alkyl ether phosphate or its salt, monoalkyl phosphate or its salt, POE/POP alkyl ether phosphate or its salt, etc. Examples of POE alkyl ether phosphate or its salt include POE lauryl ether phosphate, sodium POE oleyl ether phosphate, sodium POE lauryl ether phosphate, sodium POE cetyl ether phosphate, etc. Examples of monoalkyl phosphate or its salt include lauryl phosphate, etc. Examples of POE/POP alkyl ether phosphate or its salt include POE(10)POP(5) cetyl ether phosphate, etc. These anionic surfactants having a phosphate group can be used alone or in combination of two or more.

Examples of anionic surfactants having a carboxyl group include alkyl ether carboxylic acids or their salts, and N-acyl amino acids or their salts. Examples of alkyl ether carboxylic acids or their salts include polyoxyethylene lauryl ether acetic acid and sodium polyoxyethylene lauryl ether acetate. Examples of N-acyl amino acids or their salts include sodium coconut oil fatty acid sarcosine, sodium N-coconut oil fatty acid acyl-L-glutamate, sodium N-myristoyl-L-glutamate, and the like. These anionic surfactants having a carboxyl group can be used alone or in combination of two or more.

Examples of anionic surfactants having a sulfate group include POE alkyl ether sulfate or its salt, alkyl sulfate or its salt, and N-acyltaurate salts. Examples of POE alkyl ether sulfate or its salt include sodium POE lauryl ether sulfate, POE alkyl (12,13) ether sulfate triethanolamine (3E.O.), and the like. Examples of alkyl sulfate or its salt include sodium lauryl sulfate, hydrogenated sodium coconut oil fatty acid glyceryl sulfate, and the like. Examples of N-acyltaurate salts include sodium coconut oil fatty acid methyl taurate, sodium lauroyl methyl taurate, and the like. These anionic surfactants having a sulfate group can be used alone or in combination of two or more.

Among the above anionic surfactants, from the viewpoint of further enhancing the effect of improving emulsion stability and usability, anionic surfactants having a phosphate group are preferred, POE alkyl ether phosphate or a salt thereof is more preferred, and sodium POE cetyl ether phosphate is even more preferred.

When the emulsion composition of the present invention contains other surfactants, the content of the other surfactants is, for example, 0.1 to 3% by weight, preferably 0.5 to 2.5% by weight, and more preferably 1.2 to 1.8% by weight.

When the emulsion composition of the present invention contains a polyhydric alcohol, the content of the polyhydric alcohol is, for example, 1 to 30% by weight, and from the viewpoint of further enhancing the effect of improving emulsion stability and usability, preferably 6 to 20% by weight, more preferably 8 to 15% by weight, and even more preferably 10 to 12% by weight. Furthermore, among the polyhydric alcohols, from the viewpoint of further enhancing the effect of improving emulsion stability and usability, it is preferable to contain at least 1,3-butylene glycol. Furthermore, when the emulsion composition of the present invention contains 1,3-butylene glycol, the content of 1,3-butylene glycol is, from the viewpoint of further enhancing the effect of improving emulsion stability and usability, preferably 1 to 10% by weight, more preferably 2 to 8% by weight, and even more preferably 4 to 6% by weight.

Formulation form The formulation form of the emulsion composition of the present invention is not particularly limited, and examples thereof include liquid, semi-solid (gel, paste) and solid. From the viewpoint of further enhancing the effect of improving the feeling of use, the formulation form is more preferably liquid, gel or paste.

Specific examples of the emulsion composition of the present invention include oil-in-water emulsions and water-in-oil emulsions, and preferably oil-in-water emulsions.

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 external composition of the present invention is not particularly limited, but examples thereof include lotions, creams, ointments, emulsions, gels, oils, liniments, and aerosols.

The emulsion composition of the present invention is prepared by mixing the above-mentioned components (A) to (F) and other medicinal ingredients, additives, etc., which are blended as necessary, in the usual order in desired amounts in accordance with a typical emulsion composition manufacturing method. The emulsion composition of the present invention can be more easily prepared by using a self-emulsifying wax in which the above-mentioned component (B1) and at least a part of the above-mentioned component (C) are prepared in advance as a mixture.

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

The compositions shown in Table 1 were prepared. The properties of the emulsion compositions formed from the compositions shown in Table 1 were semi-solid (paste-like). Specifically, a solubilized phase obtained by dissolving and mixing a fat-soluble component, an oily base, and a nonionic surfactant at 80°C was added to a room temperature solution containing a sufficiently stirred aqueous base (other than polyhydric alcohol), a polyhydric alcohol, and a thickener, and the mixture was stirred to obtain an emulsion composition. The details of the components used in Table 1 are as follows.
Medium-chain fatty acid triglyceride: Triester F-810 manufactured by Nikko Chemicals Co., Ltd.
Dimethylpolysiloxane: Dow Corning Q7-9120 350CST
Polyoxyethylene arachidyl ether/stearyl alcohol mixture (self-emulsifying wax): NIKKOL WAX manufactured by Nikko Chemicals Co., Ltd.
Polyoxyethylene behenyl ether: NIKKOL BB-30 manufactured by Nikko Chemicals Co., Ltd.
Sodium polyoxyethylene cetyl ether phosphate: NIKKOL TCP-5 manufactured by Nikko Chemicals Co., Ltd.
Polyquaternium-51: Lipidure manufactured by Nippon Oil & Fats Co., Ltd. (an aqueous solution containing 5% by weight of Polyquaternium-51, blended so that the content of Polyquaternium-51 in Lipidure is as shown in Table 1.)
Sodium carboxymethylcellulose: Cellogen P-815C manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
Hydroxyethyl cellulose: HEC CF-W manufactured by Sumitomo Seika Chemicals Co., Ltd.
Sodium alginate: I-1 manufactured by Kimika Co., Ltd.

<Emulsion stability>
The appearance of each of the obtained compositions was visually observed immediately after preparation and after storage at room temperature (25° C.) for 24 hours from the preparation, and the emulsion stability was evaluated according to the following criteria. The results are shown in Table 1.
⊚: An emulsion composition was formed, and separation was not observed even after 24 hours, and the composition was stable.
◯: An emulsion composition was formed, and only slight separation was observed after 24 hours.
×: An emulsion composition was formed, but separation was observed after 24 hours.
XX: An emulsion composition could not be formed and separated immediately after preparation.

<Usage>
Each of the obtained compositions was applied to the inside of the forearm by trained panelists, and the feeling of use was evaluated according to the following criteria. Note that the evaluation of the feeling of use was only performed for those that were able to form an emulsion composition. The results are shown in Table 1.
⊚: The skin feels good after application and is not sticky at all.
Good: The skin absorbs well after application and is not sticky at all.
△: The product does not blend well with the skin after application and is slightly sticky.
×: The product does not blend well with the skin and feels sticky even during application.
XX: Immediately after application, the composition does not blend well with the skin, feels sticky, and also peels off during application.

As shown in Table 1, the composition of Comparative Example 4 was unable to even form an emulsion composition, and even when thickeners such as hydroxyethyl cellulose and sodium alginate were added, the emulsion state was hardly improved (Comparative Example 3), and some compositions still were unable to even form an emulsion composition (Comparative Examples 1 and 2). In contrast, the compositions of Examples 1 to 3 provided excellent emulsion stability and usability.

Claims (5)

The composition comprises (A) a fat-soluble active ingredient, (B) an oily base, (C) a nonionic surfactant, (D) water, (E) a phosphocholine group-containing polymer, and (F) carboxymethylcellulose and/or a salt thereof ,
The content of the component (A) is 3 to 10% by weight,
An emulsion composition , wherein the content of the component (E) is 0.1 to 1% by weight . The emulsion composition according to claim 1, wherein the content of component (B) is 0.5 to 4% by weight. The emulsion composition according to claim 1 or 2, wherein the component (B) contains a solid oil base. The emulsion composition according to any one of claims 1 to 3 , wherein the content of the component (F) is 0.1 to 10% by weight. The emulsion composition according to any one of claims 1 to 4 , comprising 0.1 to 3 parts by weight of the component (F) per 1 part by weight of the component (B).