Oil-in-water emulsion cosmetics

Abstract

An oil-in-water emulsified cosmetic comprising an aqueous medium; an alkali-soluble polymer having a carboxyl group and an amphiphilic side chain, wherein the amphiphilic side chain comprises a hydrophobic block and a hydrophilic block and is bonded to a main chain at the end of the hydrophilic block; a nonionic surfactant having a C3-C6 straight-chain or cyclic polyol residue and an HLB of 6.0-12.0; a liquid oil; and a paste oil.

Description

Technical Field

[0001] The present invention relates to an oil-in-water emulsified cosmetic. Background Art

[0002] Oil-in-water emulsions are cosmetics that are capable of moisturizing the skin to a greater extent while maintaining a watery light sensation, compared to soluble transparent preparations that do not substantially contain an oil component, and therefore, they are used in various skin care products.

[0003] An oil-in-water emulsion generally comprises an aqueous component, an oil component, and a surfactant for emulsifying the oil component, and the aqueous component generally comprises components such as a polyol and a polysaccharide (for example, see PTL 1).

[0004] [Citation list]

[0005] [Patent Document]

[0006] [PTL 1] Japanese Unexamined Patent Application Publication No. 2017-31092 Summary of the invention

[0007] In the aqueous component, synthetic water-soluble polymers, buffers and water-soluble active substances are generally included in addition to polyols or polysaccharides because they can provide moisturizing effects, but the present inventors have found that these components make the cosmetic have a heavier and stickier texture even when added in small amounts.

[0008] This problem in formulating such cosmetics has been a technical obstacle that hinders the development of oil-in-water emulsified cosmetics having freshness and moisturizing effects and less viscosity, and thus such products have not yet been marketed.

[0009] The object of the present invention is to provide an oil-in-water emulsified cosmetic which has a moist and light feeling without being sticky and can still exhibit a long-lasting moisturizing effect.

[0010] The present invention provides an oil-in-water emulsified cosmetic, which comprises (A) an aqueous medium; (B) an alkali-soluble polymer having a carboxyl group and an amphiphilic side chain, wherein the amphiphilic side chain comprises a hydrophobic block and a hydrophilic block and is bonded to a main chain at the end of the hydrophilic block; (C) a nonionic surfactant, wherein the nonionic surfactant has at least one C3-C6 linear or cyclic polyol residue and an HLB of 6.0-12.0; (D) a liquid oil; and (E) a paste oil, wherein the mass ratio of the paste oil (E) to the liquid oil (D) is greater than 0 and not greater than 1, provided that the oil-in-water emulsified cosmetic does not contain a silicone-based oil component.

[0011] Hereinafter, "aqueous medium (A)" is also referred to simply as "component (A)", and other components are referred to similarly.

[0012] The hydrophilic block may be bonded to the hydrophobic block.

[0013] The oil-in-water emulsified cosmetic of the present invention exhibits a satisfactory feeling during use due to its excellent freshness and lack of stickiness, and at the same time, it has a long-lasting moisturizing effect. In addition, the emulsified cosmetic without silicone-based oil components prevents a greasy feeling. The emulsified state also remains stable for a long time. Most consumers have high requirements for the moisturizing effect of skin care products, and also expect a moist and shiny feeling, and the oil-in-water emulsified cosmetic of the present invention meets these requirements.

[0014] Component (B) has a hydrophilic block on the side chain and also contains a carboxyl group, which facilitates swelling, dispersion or dissolution in water, and exhibits satisfactory water solubility under neutral to alkaline conditions.

[0015] On the other hand, component (B) also has a hydrophobic block at the end of the side chain, so its hydrophobic part associates with the hydrophobic group (C3-C6 linear or cyclic polyol residue) of the nonionic surfactant to form an associated complex in component (A). The oil-in-water emulsified cosmetic of the present invention produces a non-sticky light feeling, and this effect is attributed to the combination between the associative polymer (component (B)) and component (C).

[0016] Component (B) is an associative water-soluble polymer that not only imparts viscosity to an oil-in-water emulsified cosmetic but also has emulsifying ability for an oil agent, and when component (B) is added alone to a cosmetic to impart viscosity and emulsifying ability, component (B) generates stickiness on the skin similarly to when other water-soluble polymers are used. However, according to the present invention, component (B) and component (C) generate an associative complex, so that a high emulsifying ability can be exhibited even when a relatively small amount of (B) is added, and thus no stickiness is generated.

[0017] The oil-in-water emulsified cosmetic of the present invention further comprises an oil agent, which is a combination of component (D) and component (E) and exhibits a long-lasting moisturizing effect. The addition of the oil agent increases the viscosity and may cause the formation of an association complex, thereby enhancing the moisturizing effect and also improving the stability of the cosmetic.

[0018] The oil in oil-in-water emulsified cosmetics provides moisturizing effects without causing stickiness, but it is difficult to stably emulsify and disperse the oil in an aqueous medium. Common methods to solve this problem are to add excess surfactants, or use co-surfactants and water-soluble thickeners. Such formulations stabilize the cosmetics, but still produce undesirable heaviness and stickiness.

[0019] However, the oil-in-water emulsified cosmetic of the present invention does not require the addition of an excessive amount of surfactant, and can provide sufficiently high stability to the emulsion without adding other components for improving the emulsification stability.

[0020] The alkali-soluble polymer may contain an alkoxycarbonyl group and an amphiphilic side chain having a C12-C24 hydrocarbon backbone as a hydrophobic block and a polyoxyethylene backbone as a hydrophilic block. The nonionic surfactant may have a glycerol residue, a sorbitol residue or a sucrose residue, and its HLB may be 6.0-12.0.

[0021] For component (B) and component (C), using the above respective structures will increase their ability to form an associated complex and produce the excellent effects of the present invention, namely, providing freshness, preventing stickiness and imparting moisture, while also exhibiting greater emulsion stability.

[0022] The mass ratio of the pasty oil to the liquid oil may be greater than 0 and not greater than 1.

[0023] Compared with liquid oil, paste oil exhibits greater moisturizing and viscosity reducing effects, but excessive addition of paste oil may not be desirable from the perspective of emulsion stability. When the mass ratio of the paste oil is within the above range, the oil-in-water emulsified cosmetic of the present invention exhibits very satisfactory stability.

[0024] One or both of the liquid oil and the paste oil may be a polar oil. That is, a polar liquid oil and / or a polar paste oil may be used. By using such an oil, the moisturizing effect will be more lasting.

[0025] According to the present invention, there is provided an oil-in-water emulsified cosmetic having a moist and light feel without being sticky and still being able to exhibit a sufficient and long-lasting moisturizing effect. DETAILED DESCRIPTION

[0026] Embodiments of the present invention will now be described with the understanding that they are not intended to limit the invention.

[0027] Component (A) in the oil-in-water emulsified cosmetic of this embodiment is an aqueous medium containing at least water (as a medium for components (B) to (E)). Component (A) may consist of water alone, or may contain other water-soluble components in water.

[0028] The water-soluble components include polyols, monools, polysaccharides, nonionic surfactants other than component (C), anionic surfactants, cationic surfactants, amphoteric surfactants, buffers, preservatives, synthetic water-soluble polymers, ultraviolet absorbers, ultraviolet scatterers, antimicrobial agents, anti-inflammatory agents, fragrances, antioxidants, pH adjusters, chelating agents, vitamins, amino acids and plant extracts.

[0029] Examples of polyols include butylene glycol, pentylene glycol and glycerol, and examples of polysaccharides include sulfated polysaccharides. Usable nonionic surfactants (except component (C)) include ethylene oxide addition products of sorbitan fatty acid esters, such as polysorbate 20 (HLB: 16.7), polysorbate 60 (HLB: 14.9) and polysorbate 80 (HLB: 15); and sorbitan fatty acid esters, such as sorbitan sesquioleate (HLB: 5).

[0030] Sodium phosphate, disodium phosphate and disodium EDTA are typical buffers that may be used, phenoxyethanol is a typical preservative, and ethanol is a typical monohydric alcohol.

[0031] Component (B) in the oil-in-water emulsified cosmetic is an alkali-soluble polymer comprising a carboxyl group and an amphiphilic side chain comprising a hydrophobic block and a hydrophilic block and bonded to the main chain at the end of the hydrophilic block.

[0032] That is, component (B) has at least a carboxyl group and an amphiphilic side chain which includes a hydrophobic block and a hydrophilic block and is bonded to the main chain at the end of the hydrophilic block.

[0033] The hydrophobic block is a block that is longer than one carbon atom and is hydrophobic in itself, and the block is generally a hydrocarbon backbone. The hydrophobic block is preferably a hydrocarbon backbone with 12-24 carbon atoms; more preferably, the hydrophobic block is an alkyl group of C12-C24. Such alkyl groups include dodecyl (lauryl), tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl and behenyl. The alkyl group preferably has an even number of carbons, and is preferably dodecyl, octadecyl or behenyl.

[0034] The hydrophilic block is a block that is longer than one carbon atom and is hydrophilic in itself, and the block is generally a polyoxyalkylene backbone. The hydrophilic block is preferably composed of a polyoxyethylene backbone, which may have 10-30 oxyethylene repeating units. That is, the hydrophilic block preferably has a -(CH2CH2O)n- backbone, wherein n is 10-30, more preferably 12-25, and even more preferably 20-25. The hydrophilic block may be directly bonded to the main chain, or bonded through a joint. The joint may be an oxycarbonyl (-CO-O-), the -O- portion preferably being bonded to the carbon atoms of the polyoxyalkylene backbone.

[0035] Component (B) may have an alkoxycarbonyl group, and the alkyl group of the alkoxycarbonyl group is preferably a C1-C24 alkyl group. Such alkyl groups include methyl, ethyl, butyl, hexyl, octyl, decyl, dodecyl (lauryl), tetradecyl, hexadecyl, octadecyl, eicosyl and behenyl.

[0036] Component (B) is preferably a polymer comprising an ethylenically unsaturated compound having a carboxyl group and an ethylenically unsaturated compound having the above-mentioned amphiphilic group as repeating units, and it may also have an ethylenically unsaturated compound having the above-mentioned alkoxycarbonyl group as an additional repeating unit. A more preferred polymer is a polymer comprising (meth)acrylic acid, (meth)acrylic acid alkyl ester and (meth)acrylic acid polyoxyethylene monoalkyl ether ester as repeating units [i.e., (meth)acrylic acid / (meth)acrylic acid alkyl ester / (meth)acrylic acid-POE-monoalkyl ether ester copolymer)]. The term "(meth)acrylic acid" means acrylic acid or methacrylic acid, and the same applies to other analogs such as (meth)acryloyl.

[0037] Component (B) is an alkali-soluble water-soluble polymer that not only imparts viscosity to cosmetics but also has emulsifying ability for oil agents. Specifically, it can be used to disperse in an aqueous medium of a formulation and neutralize with a base such as sodium hydroxide. Component (B) can also be referred to as a hydrophobically modified alkali-soluble polymer. An example of component (B) is Aculyn® from Dow Chemical Corp. TM 22 and Aculyn TM 28.

[0038] The viscosity increases dramatically by combining component (B) with component (C). This phenomenon occurs because the hydrophobic residues (e.g., alkyl groups) of component (B) and component (C) interact with each other in the oil-in-water emulsified cosmetic to form an associated complex. The associated complex formed by even a small amount of component (B) and component (C) produces a characteristic feeling when applied to the skin because they immediately change from a gel form to a liquid form.

[0039] Component (C) in the oil-in-water emulsified cosmetic is a nonionic surfactant having at least one C3-C6 linear or cyclic polyol residue and an HLB of 6.0-12.0. That is, component (C) contains at least one C3-C6 linear polyol residue or C3-C6 cyclic polyol residue, and its HLB is within the range specified above. When the HLB is less than 6.0, the solubility in the aqueous medium decreases and the emulsification stability decreases. In addition, it is impossible to obtain the effects achieved by the present invention (a moist and light feeling without stickiness and a sufficiently long-lasting moisturizing effect). On the contrary, when the HLB exceeds 12.0, the freshness and emulsification stability deteriorate, and the above-mentioned effects cannot be obtained.

[0040] HLB is a commonly used hydrophile-lipophile balance value in the field of surfactants. It can be calculated using conventional formulas, such as the following formula published by Oda and Teramura:

[0041] HLB = (Σinorganic value) × 10 / (Σorganic value)

[0042] When the nonionic surfactant is a commercial product, the HLB value listed in the product catalogue can be used.

[0043] A glycerol residue is an example of a C3 straight-chain polyol residue, a sorbitol residue is an example of a C6 straight-chain polyol residue, and a sucrose residue is an example of a polyol residue having two C6 cyclic residues.

[0044] Component (C) may be a fatty ester of an oxyethylene addition product of a C3-C6 straight chain or cyclic polyol. The fatty acid may be used alone or in combination of two or more. The alkyl portion of the fatty acid may be a C6-C24 alkyl, examples of which include hexyl, octyl, decyl, dodecyl (lauryl), tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, and behenyl. An example of this type of component (C) is polyoxyethylene (20) glyceryl triisostearate (e.g., PEG-20 glyceryl triisostearate).

[0045] Alternatively, component (C) can be a fatty acid ester of an oxyethylene addition product of a C3-C6 straight chain or cyclic polyol. Examples of such component (C) also include polyoxyethylene hydrogenated castor oil and sorbitol oxyethylene addition product fatty acid esters. As an example of the polyoxyethylene hydrogenated castor oil, PEG-10 hydrogenated castor oil can be cited. Furthermore, as an example of sorbitol oxyethylene addition product fatty acid esters, sorbitol oxyethylene addition product oleic acid esters (sorbitol polyether-6 tetraoleate, sorbitol polyether-30 tetraoleate, etc.) can be cited.

[0046] The HLB of component (C) is preferably 7.0 to 12.0, more preferably 8.0 to 12.0. When the HLB of component (C) is within this medium range, a satisfactory interaction is obtained between the hydrophobic residues of component (C) and component (B), so that the oil-in-water emulsified cosmetic exhibits a moist feel without stickiness.

[0047] Component (D) and component (E) in the oil-in-water emulsified cosmetic are oils, particularly liquid oils and paste oils, respectively. Any paste oil may be used without particular limitation as long as it is in a paste form at 25°C and can be used in cosmetics, but it is preferred to use an ester oil and / or hydrocarbon oil having a viscosity of 10,000 mPa·s or more at 25°C as measured with a Brookfield rotational viscometer. Liquid oil is an oil having a viscosity of less than 10,000 mPa·s under the same conditions. If the viscosity is too high, it may be judged as a paste oil when the consistency at 30°C (based on JIS-K-2220) is greater than 150.

[0048] Adding such an oil agent will promote the formation of an association complex (the association complex synergistically increases viscosity) and will produce an oil-in-water emulsified cosmetic that maintains its stability. The oil-in-water emulsified cosmetic exhibits a moist and light feeling without stickiness and maintains a long-lasting moisturizing effect. Compared with water-soluble components, ordinary oil agents other than silicone-based oil components have the property of more easily penetrating the stratum corneum of the skin, and thus can impart a greater moisturizing effect, but tend to be more difficult to ensure the stability of the oil-in-water emulsified cosmetic compared to preparations without oil agents. However, according to the present invention, the above-mentioned effects are obtained due to the formation of an association complex, and the combination of liquid oil and pasty oil makes it possible to improve the moisturizing effect while further reducing the viscosity.

[0049] Liquid oils include isononyl isononanoate, isotridecanyl isononanoate, ethylhexyl palmitate, cetyl ethylhexanoate, neopentyl glycol diethylhexanoate, neopentyl glycol dicaprate, triisooctanoin, glyceryl tri(caprylate / caprate), triisostearin, trimethylolpropane triisostearate, pentaerythritol tetraethylhexanoate, pentaerythritol tetraisostearate, polyglyceryl-2 tetraisostearate, propylene glycol di(caprylate / caprate), propylene glycol diisostearate, and polyglyceryl-6 octaoctanoate.

[0050] Other liquid oils include octyldodecanol lactate, diisostearyl malate, polyglyceryl-2 isostearate, polyglyceryl-2 diisostearate, polyglyceryl-2 triisostearate, ditrimethylolpropane (isostearate / sebacate) oligoesters, erythritol triethylhexanoate, dipentaerythritol tripolyhydroxystearate, trehalose isostearate, dipentaerythritol pentaisostearate, ethylhexyl hydroxystearate, polyhydroxystearic acid, liquid paraffin, squalane, α-olefin oligomers, isododecane and isohexadecane.

[0051] Paste oils include vegetable oil paste, shea butter (Butyrospermum parkii), mango seed butter (Mangifera indica) and avocado oil (Persea gratissima), cholesterol hydroxystearate, phytostearyl hydroxystearate, phytostearyloleate, dipentaerythrityl hexa(hydroxystearate / stearate / rosinate), dipentaerythrityl tetra(hydroxystearate / isostearate), dipentaerythrityl hexahydroxystearate, glyceryl (ethylhexanoate / stearate / adipate), glyceryl tri(caprylate / caprate / myristate / stearate), hydrogenated palm oil, petrolatum and dipentaerythrityl hexa(behenate / benzoate / ethylhexanoate).

[0052] From the perspective of the sustainability of moisturizing effects, polar oils are superior to non-polar oils for both liquid oils and paste oils. Preferred polar liquid oils include isononyl isononanoate and ethylhexyl palmitate, and preferred polar paste oils include vegetable oil pastes, especially vegetable oils, shea butter, mango seed butter, and avocado oil.

[0053] The mass ratio of the paste oil to the liquid oil is preferably greater than 0 and not greater than 1, and more preferably in the range of 0.1-0.8, particularly 0.2-0.5. When the mass ratio of the oil paste is within this range, it is possible to impart very satisfactory stability to the oil-in-water emulsified cosmetic.

[0054] The content of component (B) is preferably 0.05% to 2.0% by mass, the content of component (C) is preferably 0.05% to 5.00% by mass, and the total content of component (D) and component (E) is preferably 1% to 40% by mass. Component (A) constitutes the remaining content. These contents are based on the total mass of the oil-in-water emulsified cosmetic.

[0055] The viscosity of the oil-in-water emulsified cosmetic at 25°C is preferably 1000 mPa·s or more. The viscosity is more preferably 1000 mPa·s to 10,000 mPa·s, and even more preferably 1000 mPa·s to 5000 mPa·s. The viscosity within this range will improve the stability of the oil-in-water emulsified cosmetic and give it an excellent feel during use.

[0056] The oil-in-water emulsified cosmetic can be obtained by mixing and stirring component (A), component (B), component (C), component (D) and component (E), or by mixing and neutralizing component (B) in component (A), and then adding to component (C), component (D) and component (E) and stirring.

[0057] Example

[0058] The present invention will now be described by way of examples, but it should be understood that the present invention is not intended to be limited to these examples.

[0059] Using the compositions listed in Tables 1 to 3, an aqueous medium (column "A"), an oil agent (column "B"), a nonionic surfactant (column "C"), a co-surfactant and a polymer component (column "D") were mixed and stirred to prepare oil-in-water emulsified cosmetics for Examples 1 to 6 and Comparative Examples 1 to 12. For formulation, the polymer component was mixed and neutralized in an aqueous medium, and a mixture of an oil agent and a nonionic surfactant was added and mixed with the solution to obtain an oil-in-water emulsified cosmetic. The content (mass %) of each material is shown in Tables 1 to 3.

[0060] <Sensory Evaluation>

[0061] The moisturizing effect persistence, freshness and stickiness of the oil-in-water emulsified cosmetics of Examples and Comparative Examples were evaluated by a cosmetic expert evaluation panel of the organization to which the inventor belongs in a single use test on the skin, and the evaluation was performed according to the following criteria.

[0062] (1) Durability of moisturizing effect and freshness

[0063] A: Strong

[0064] B: Medium

[0065] C: Almost nothing

[0066] D: None

[0067] (2) Non-sticky

[0068] A: No stickiness at all

[0069] B: Almost no stickiness

[0070] C: Slightly sticky

[0071] D: Viscosity

[0072] <Evaluation of emulsion stability>

[0073] The emulsion stability of the oil-in-water emulsified cosmetics of the examples and comparative examples was evaluated. Each cosmetic was filled into a transparent container and sealed with a cap, and then stored at 50°C for 1 month. Any separation between the oil phase and the water phase after storage was observed. The separation degree of the oil phase and the water phase after storage was evaluated in 4 levels from A to D from low separation to high separation. The results are shown in Table 1.

[0074]

[0075]

[0076]

Claims

1. An oil-in-water emulsified cosmetic, comprising: (A) an aqueous medium comprising water and a polyol, (B) 0.05% by mass to 2.0% by mass of an alkali-soluble polymer having a carboxyl group and an amphiphilic side chain, the amphiphilic side chain comprising a hydrophobic block and a hydrophilic block and bonded to the main chain at the end of the hydrophilic block, (C) 0.05% to 5.00% by mass of a nonionic surfactant, wherein the nonionic surfactant is a fatty acid ester of an ethylene oxide addition product of glycerol, the alkyl portion of the fatty acid is a C6-C24 alkyl, and the HLB of the nonionic surfactant is 6.0-12.0, (D) polar liquid oil, and (E) vegetable paste oil, in, The total content of component (D) and component (E) is 1% to 40% by mass. Wherein component (A) constitutes the remaining content, wherein the mass ratio of the pasty oil (E) to the liquid oil (D) is in the range of 0.2-0.5, and the oil-in-water emulsified cosmetic does not contain a silicone-based oil component, The mass content is based on the total mass of the oil-in-water emulsified cosmetic.

2. The oil-in-water emulsified cosmetic according to claim 1, wherein The alkali-soluble polymer further comprises an alkoxycarbonyl group, and the amphiphilic side chain comprises a C12-C24 hydrocarbon backbone as the hydrophobic block and a polyoxyethylene backbone as the hydrophilic block.

3. The oil-in-water emulsified cosmetic according to claim 1 or 2, wherein: The nonionic surfactant is PEG-20 glyceryl triisostearate.

4. The oil-in-water emulsified cosmetic according to claim 1 or 2, wherein: One of the liquid oil and the paste oil is a polar oil agent or both are polar oil agents.

5. The oil-in-water emulsified cosmetic according to claim 3, wherein: One of the liquid oil and the paste oil is a polar oil agent or both are polar oil agents.

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