JP7562917B2 - Cosmetics - Google Patents

Description

The present invention relates to a multi-layered liquid cosmetic.

Liquid cosmetics consisting of two layers, an oil layer and an aqueous layer (see Patent Document 1), liquid cosmetics consisting of an aqueous layer and a powder layer containing an insoluble powder, and even multi-layer liquid cosmetics consisting of three or more layers, such as an aqueous layer, an oil layer and a powder layer (see Patent Document 2) are known. These multi-layer liquid cosmetics have an appearance of being separated into multiple layers before use. When used, they are shaken to temporarily turn the entire product into a uniform emulsion or mixed cosmetic solution, which is then applied to the skin. After use, they are allowed to stand and re-form into a multi-layered solution.

The most common multi-layer liquid cosmetic is a two-layer cosmetic having an interface between liquids with different properties, consisting of an unemulsified oil layer and an aqueous layer. In such a two-layer cosmetic, either the oil layer or the aqueous layer is generally colored, or both layers are colored in different colors to clarify the interface between the two layers and emphasize the beauty of the appearance. Furthermore, a three-layer cosmetic can be made by adding a sedimentary powder. Such two-layer or three-layer cosmetic is often filled in a transparent container to make a product that takes advantage of the appearance characteristic of being multi-layered. When the contents filled in a transparent container are exposed to ultraviolet rays or fluorescent lights, the coloring components fade to a certain extent. For this reason, it is problematic that measures against this require extra effort. In addition, when an excessive amount of coloring components is added to make the interface between the layers clear, it can cause problems such as coloring of the skin and staining of clothes.
Furthermore, in liquid cosmetics consisting of two layers, an unemulsified oil layer and an aqueous layer, the oil layer and the aqueous layer are easily separated, so that when applied to the skin or hair, it is easy to get an emollient feeling immediately, but since an oily feeling is felt on the skin or hair during application, it is often the case that a fresh feeling is not obtained during application. And, if a solid or paste-like oil agent is blended into the oil layer of this two-layer cosmetic consisting of an oil layer and an aqueous layer in the hope of further improving the moisturizing effect, crystals may precipitate in the oil layer or the oil layer itself may solidify during long-term storage, making it difficult to maintain the quality, and therefore, it has rarely been blended. Thus, it has generally been said that it is difficult for two-layer cosmetics consisting of an oil layer and an aqueous layer to obtain a fresh feeling when applied, a high moisturizing effect after application, and a stable appearance.

On the other hand, liquid cosmetics consisting of two layers, an emulsion layer and an aqueous layer, have been proposed (see Patent Documents 3 and 4). In these cosmetics, the emulsion layer is milky white, so even without blending coloring components, the boundary between the emulsion layer and the aqueous layer is visible, and problems caused by coloring components no longer occur.

Furthermore, liquid cosmetics consisting of two layers, an emulsion layer and an aqueous layer, have also solved the problem of freshness during application. In other words, when a two-layer cosmetic consisting of an emulsion layer and an aqueous layer is shaken, the emulsion layer easily disperses into the aqueous layer, temporarily homogenizing the entire cosmetic, and this homogenized cosmetic gives a fresh feeling of use during application. Furthermore, since the oil contained is emulsified in the emulsion layer, even if a solid or paste-like oil agent is blended in the cosmetic in hopes of further moisturizing effects, it is expected that crystal precipitation will be less likely to occur during long-term storage compared to two-layer cosmetics of oil-aqueous layer type. In this way, by making one layer of a two-layer cosmetic into an emulsion layer, it has become possible to some extent to ensure a fresh feeling of use during application and to vary the product with improved durability of moisturizing effects.
However, it is said that it is difficult to simultaneously achieve a two-layer cosmetic composition consisting of an emulsion layer and an aqueous layer, which is shaken when used to temporarily create a uniform state, and then left to stand for a certain period of time to quickly separate into the original two-layer state of the emulsion layer and the aqueous layer, and to stabilize the emulsion layer over time. For example, when a two-layer cosmetic composition is left to stand, the emulsion particles aggregate, causing creaming, and the emulsion layer separates into two layers, but if the design does not sufficiently ensure the stability of the emulsion layer (particularly in this case, a design in which the emulsion particles frequently coalesce and the emulsion particles continue to grow), not only does it cause a three-layer separation in which the oil layer is separated from the emulsion layer, damaging the aesthetic appearance, but also causes problems such as solidification of the separated oil layer depending on the oil agent. When a large amount of thickeners, surfactants, etc. are added to increase the emulsion stability of the emulsion layer, the separation speed of the two layers tends to slow down, which is a problem (first problem). In addition to this, for unknown reasons, part of the emulsion layer may remain in the aqueous layer, causing the aqueous layer to become cloudy or the boundary to become unclear (second problem). Although the two-layer cosmetic composition in this state is separated, it is difficult to say that the appearance of the composition is beautiful. It is known that the cloudiness of the water layer is reduced by slowing down the separation speed. Therefore, it has been pointed out that liquid two-layer cosmetic compositions consisting of an emulsion layer and a water layer, which have the second problem, generally have one of two problems: either the separation speed is slow in order to ensure the transparency of the water layer, or the water layer becomes very cloudy after separation because the separation speed is prioritized.
In other words, in two-layer cosmetics consisting of an emulsion layer and an aqueous layer, the problems of three-layer separation, in which an oil layer separates from the emulsion layer, problems such as solidification of the separated oil layer depending on the oil agent, and problems of turbidity of the aqueous layer frequently occur individually or in combination, and it was not easy to design the formulation. In addition to solving all of these problems and obtaining a cosmetic with a beautiful appearance and an appropriate separation speed, a good usability as a cosmetic is also an essential quality requirement, so in the conventional technology, the formulation designer was required to go through excessive trial and error.

Patent documents 5 to 7 describe two-layer cosmetics consisting of an emulsion layer and an aqueous layer, which have good storage stability. However, none of them are satisfactory. It has been pointed out that the cosmetics disclosed in Patent documents 5 and 6 require a long time for separation after mixing by shaking, and the aqueous layer after separation is likely to become cloudy. In addition, it has been pointed out that the cosmetic of Patent document 7 contains a small amount of oil, and thus lacks the moisturizing properties required for cosmetics. Furthermore, it has been pointed out that after shaking, a certain amount of time is required for the transparency of the lower aqueous layer to improve after standing.
Patent Document 8 describes a two-layer cosmetic composition that contains phospholipids and a water-soluble polymer as essential components and that is composed of an emulsion layer and an aqueous layer and that separates quickly into two layers.

JP 2010-280593 A JP 2020-26401 A Japanese Patent Application Publication No. 10-316539 Japanese Patent Application Publication No. 4-112811 JP 2013-75867 A JP 2004-203764 A JP 2003-137728 A JP 2001-213720 A

The present invention aims to provide a multi-layer liquid cosmetic composition consisting of an emulsion layer and an aqueous layer, which has a fast separation speed after mixing by shaking, a high transparency of the aqueous layer after separation, a fresh feel when applied, an excellent emollient feel after application, and good storage stability.

The present invention comprises the following configuration.
(1) A multi-layered liquid cosmetic composition comprising the following components (A) to (C):
(A) a polyoxyethylene fatty acid diester having an average number of moles of oxyethylene groups added of 50 or more and 300 or less; (B) a nonionic surfactant different from component (A) and having an HLB of 12 or more; (C) an oily agent that is liquid at 25°C; (2) the multi-layered liquid cosmetic composition according to (1), wherein component (A) is a diester of a linear saturated fatty acid having 12 to 18 carbon atoms and polyethylene glycol.
(3) A multi-layered liquid cosmetic according to (1) or (2), in which the mass ratio of component (A) to component (B) contained in the cosmetic is (A):(B) = 1:1 to 1:20.

The multi-layered liquid cosmetic of the present invention becomes uniformly mixed or emulsified simply by shaking, and after use, it quickly separates into an emulsified layer and an aqueous layer simply by leaving it to stand for about 1 hour. The boundary surface after separation is clear. Therefore, the clear difference between the layers can be confirmed without coloring. In addition, the aqueous layer becomes transparent without turbidity or suspended matter. Since the aqueous layer after separation is highly transparent, it can be provided to consumers as an aesthetically excellent cosmetic.
In addition, the oily agent of component (C) contained in the cosmetic of the present invention is present in a stable state within the emulsion layer, and therefore, upon application, the cosmetic gives a fresh feel to the skin and hair without causing an oily (sticky) feeling due to the oily agent, and after application, the cosmetic gives a pleasant emollient (moist) feeling to the skin and hair.
Furthermore, the emulsified state of the emulsion layer after separation into two layers is extremely stable, and even after storage in an environment of 50°C for one month or more, no crystal precipitation, no appearance of an oily layer (three layers), or solidification of the emulsion layer occurs.

The present invention is a cosmetic preparation which becomes uniformly mixed or emulsified simply by shaking, and after use, is clearly separated into an emulsified layer and an aqueous layer by leaving it to stand for about 1 hour, and the aqueous layer becomes transparent. Note that, in the present invention, "transparent" refers to a state in which no turbidity or suspended matter is observed with the naked eye after filling a transparent glass bottle with a diameter of 4.5 cm and leaving it to stand for 1 day.
The components contained in the multi-layered liquid cosmetic of the present invention will now be described.

<Component (A): Polyoxyethylene fatty acid diester having an average number of moles of oxyethylene groups added of 50 to 300>
The fatty acid constituting the polyoxyethylene fatty acid diester is preferably a fatty acid having 10 to 20 carbon atoms, more preferably a fatty acid having 10 to 18 carbon atoms, and particularly preferably a fatty acid having 12 to 18 carbon atoms. The fatty acid constituting the polyoxyethylene fatty acid diester may be saturated, unsaturated, straight-chain, or branched, with straight-chain saturated fatty acids being particularly preferred. Furthermore, the fatty acid may be a mixed fatty acid which is a mixture of various fatty acids.
Specific examples of the fatty acid include lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, oleic acid, coconut oil fatty acid, etc. Preferred are lauric acid and stearic acid, and particularly preferred is stearic acid.

The average number of moles of ethylene oxide added to the polyoxyethylene chain constituting the polyoxyethylene fatty acid diester is 50 to 300, preferably 75 to 250, and more preferably 150 to 250. Even more preferably, it is 150 to 190. When the average number of moles of ethylene oxide added to the polyoxyethylene chain is less than 50, the transparency of the aqueous layer separated into two layers, the emulsion layer and the aqueous layer, in the cosmetic of the present invention decreases. In addition, problems may occur in the stability over time. When the average number of moles of ethylene oxide added to the polyoxyethylene chain exceeds 300, the separation speed after the emulsion layer and the aqueous layer are mixed by shaking may decrease. In addition, the stability over time may be adversely affected. In addition, in the present invention, the smaller the average number of moles of ethylene oxide added to the polyoxyethylene chain, the more the component (A) needs to be contained, and when the average number of moles of ethylene oxide added to the polyoxyethylene chain is larger, the effect is exhibited by only a small amount of the component. Therefore, in terms of formulation design, the average number of moles of ethylene oxide added to the polyoxyethylene chain constituting the polyoxyethylene fatty acid diester is preferably 150 to 250, which makes it easier to adjust the variations in the formulation, including the feeling of use.
The component (A) used in the present invention: a polyoxyethylene fatty acid diester having an average added mole number of oxyethylene groups of 50 or more and 300 or less, has an HLB of 12 or more, preferably 15 or more, and more preferably an HLB of 16 to 19.5.
Examples of the polyoxyethylene fatty acid diester used in the present invention include polyoxyethylene linear saturated fatty acid diesters such as polyethylene glycol distearate and polyethylene glycol dilaurate, polyoxyethylene unsaturated fatty acid diesters such as polyethylene glycol dioleate, and further polyoxyethylene branched fatty acid diesters such as polyethylene glycol diisostearate. Among them, polyethylene glycol distearate and polyethylene glycol dilaurate, which are highly effective in increasing the transparency of the aqueous layer after separation into two layers, are preferred, and polyethylene glycol distearate is particularly preferred. Examples of commercially available polyethylene glycol distearate surfactants include NIKKOL CDS-6000P (cosmetic ingredient name: PEG-150 distearate, manufactured by Nikko Chemicals Co., Ltd., HLB 16.5), Emulmin 862 (cosmetic ingredient name: PEG-190 distearate, manufactured by Sanyo Chemical Industries, Ltd., HLB 18), and Emanon 3299RV (cosmetic ingredient name: PEG-250 distearate, manufactured by Kao Corporation, HLB 19.2). In the cosmetic ingredient name, the number after PEG indicates the average number of moles of oxyethylene groups added.

Component (A) may be used in the cosmetic composition of the present invention either alone or in combination of two or more.
In the present invention, the content of component (A) is 0.005 to 2% by mass, preferably 0.01 to 1% by mass, and more preferably 0.01 to 0.4% by mass, based on the total amount of the cosmetic. If it exceeds 2% by mass, there is a high possibility that the separation speed will decrease and the emulsion layer will solidify over time. If it is less than 0.005% by mass, there is a high possibility that the transparency of the aqueous layer will not be improved. In order to make the appearance of the separated aqueous layer less cloudy when observed after shaking and leaving it to stand for 2 hours, the content of component (A) is preferably 0.03% by mass or more, more preferably 0.03 to 0.4% by mass, and even more preferably 0.05 to 0.4% by mass, based on the total amount of the cosmetic.

<Component (B): Nonionic surfactant with HLB of 12 or more>
The cosmetic preparation of the present invention essentially contains, as component (B), a nonionic surfactant different from component (A) and having an HLB of at least 12. By containing, as component (B), a nonionic surfactant different from component (A) and having an HLB of at least 12, it is possible to enhance stability over time.
If a nonionic surfactant with an HLB value of less than 12 is used as the surfactant of component (B), the separation speed of the emulsion layer and the aqueous layer becomes slow after the multi-layered liquid cosmetic is shaken to mix or emulsify the entire cosmetic. Furthermore, coalescence of emulsion particles occurs, and eventually problems such as separation of oil and other deterioration of stability over time may occur.
Examples of the nonionic surfactant having an HLB of 12 or more as component (B) used in the present invention include polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene fatty acid monoesters, polyoxyethylene glycerin fatty acid esters, polyoxyethylene hydrogenated castor oil, polyoxyethylene sorbitan fatty acid esters, sucrose fatty acid esters, polyglycerin fatty acid esters, etc.
Specific examples of polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether (30 E.O.) (HLB 16), polyoxyethylene lauryl ether (15 E.O.) (HLB 14), polyoxyethylene lauryl ether (12 E.O.) (HLB 13), polyoxyethylene alkyl (12-14) ether (12 E.O.) (HLB 14.5), polyoxyethylene stearyl ether (30 E.O.) (HLB 15), polyoxyethylene stearyl ether (20 E.O.) (HLB 13), polyoxyethylene oleyl ether (30 E.O.) (HLB 15), and polyoxyethylene octyldodecyl ether (20 E.O.) (HLB 13). Specific examples of polyoxyethylene polyoxypropylene alkyl ethers include PPG-4 ceteth-20 (HLB 16.5), PPG-8 ceteth-20 (HLB 12.5), and PPG-6 decyltetradeceth-30 (HLB 12).Specific examples of polyoxyethylene fatty acid monoesters include PEG-20 stearate (HLB 14), PEG-30 stearate (HLB 15), and PEG-40 stearate (HLB 16). Specific examples of polyoxyethylene glycerin fatty acid esters include PEG-30 glyceryl stearate (HLB15), PEG-40 glyceryl stearate (HLB16), PEG-50 glyceryl stearate (HLB16), PEG-60 glyceryl stearate (HLB17), PEG-30 glyceryl isostearate (HLB15), PEG-40 glyceryl isostearate (HLB15), PEG-50 glyceryl isostearate (HLB16), PEG-60 glyceryl isostearate (HLB16), and PEG-60 glyceryl diisostearate (HLB14).
Specific examples of polyoxyethylene hydrogenated castor oil include PEG-40 hydrogenated castor oil (HLB 12.5), PEG-60 hydrogenated castor oil (HLB 14), and PEG-80 hydrogenated castor oil (HLB 15).Specific examples of polyoxyethylene sorbitan fatty acid esters include polyoxyethylene sorbitan monolaurate (6 E.O.) (HLB 13.3), polyoxyethylene sorbitan monolaurate (20 E.O.) (HLB 16.7), polyoxyethylene sorbitan monopalmitate (20 E.O.) (HLB 15.6), polyoxyethylene sorbitan monostearate (20 E.O.) (HLB 14.9), and polyoxyethylene sorbitan monooleate (20 E.O.) (HLB 15). Specific examples of sucrose fatty acid esters include sucrose stearate, sucrose palmitate, sucrose myristic acid ester, sucrose oleate, and sucrose laurate, and each of these can be used with an esterification degree of HLB of at least 12. Specific examples of polyglycerin fatty acid esters include polyglyceryl-10 caprylate (HLB 16.1), polyglyceryl-6 laurate (HLB 13.4), polyglyceryl-10 laurate (HLB 14.7), polyglyceryl-10 myristate (HLB 14.8), polyglyceryl-10 stearate (HLB 14.1), polyglyceryl-10 isostearate (HLB 13.7), and polyglyceryl-10 oleate (HLB 12.9).
Among the above-listed examples of component (B), polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene fatty acid monoesters, polyoxyethylene glycerin fatty acid esters, and polyoxyethylene hydrogenated castor oil are preferred, and among these, polyoxyethylene alkyl ethers and polyoxyethylene glycerin fatty acid esters are more preferred.

In the cosmetic of the present invention, the cosmetic solution is uniformly mixed or emulsified by shaking, and after standing, it quickly separates into an emulsified layer and an aqueous layer. It is important that the separation speed between the emulsified layer and the aqueous layer is fast, that the separated state is stably maintained, that the emulsion layer is kept in a stable state, and that the transparency of the aqueous layer is maintained.
In order to stabilize the cosmetic preparation of the present invention over time, it is necessary to make it difficult for the emulsion particles in the emulsion layer to coalesce and to prevent the emulsion layer from solidifying. If the content of component (A) is greater than the content of component (B), there is a greater risk of the emulsion layer solidifying, so it is preferable to include more component (B) than component (A).
In preparing the cosmetic preparation, it is preferable to adjust the contents of both components so that the mass ratio of component (A) to component (B) contained in the cosmetic preparation is (A):(B) = 1:1 to 1:20, preferably (A):(B) = 1:3 to 1:19, and more preferably (A):(B) = 1:3.1 to 1:9.
By setting the content ratio of component (A) and component (B) within this range, the storage stability and separation speed of the emulsion layer and the transparency of the aqueous layer are improved.

<Component (C): Oil that is liquid at 25°C>
The cosmetic preparation of the present invention contains an oily agent that is in a liquid state at 25° C. Examples of the oily agent that is liquid at 25° C. and is used in the present invention include triglycerides, ester oils, hydrocarbon oils, and silicone oils.
Examples of triglycerides include olive oil, macadamia seed oil, sunflower seed oil, avocado oil, safflower oil, rice bran oil, rice germ oil, wheat germ oil, castor oil, grape seed oil, almond oil, tri(caprylic/capric acid)glyceryl, and tri-2-ethylhexanoate glyceryl. Examples of ester oils include cetyl ethylhexanoate, 1,3-butylene glycol diisononanoate, 1,3-butylene glycol di-2-ethylhexanoate, dipropylene glycol diisononanoate, dipropylene glycol di-2-ethylhexanoate, isononyl isononanoate, neopentyl glycol dicaprate, ethylhexyl palmitate, isostearyl neopentanoate, and jojoba oil. Examples of hydrocarbon oils include liquid paraffin, squalene, squalane, hydrogenated polydecene, and hydrogenated polyisobutene. Examples of silicone oils include linear polysiloxanes such as dimethylpolysiloxane and methylphenylpolysiloxane, and cyclic polysiloxanes such as decamethylcyclopentasiloxane and cyclopentasiloxane.
In the cosmetic of the present invention, the content of the oil agent that is liquid at 25° C. is preferably 1 to 30% by mass, more preferably 3 to 25% by mass, and particularly preferably 5 to 20% by mass, based on the total amount of the cosmetic. If it is less than 1% by mass, the volume of the emulsion layer in the multi-layered liquid cosmetic may become small, resulting in a poor aesthetic appearance. If it is contained in excess of 30% by mass, there is a risk that the separation speed between the emulsion layer and the aqueous layer after shaking may become slow.

<Other ingredients>
The cosmetic of the present invention may contain, as necessary, in the emulsion layer or aqueous layer, ingredients that are typically used in cosmetics, such as water-soluble polymer thickeners, water-soluble salts, moisturizing/humectants, antioxidants, UV absorbers, fragrances, preservatives, pH adjusters, blood circulation promoters, cooling agents, antiperspirants, germicides, skin activators, or other cosmetic ingredients or medicinal ingredients, provided that the effects of the invention are not impaired.

In the present invention, a small amount of water-soluble polymer thickener can be added in addition to the components of the present invention. The inclusion of a water-soluble polymer thickener makes it easier to adjust the separation speed between the emulsion layer and the aqueous layer. Although the separation speed is sufficient by adopting the configuration of the present invention, a water-soluble polymer thickener can be added for the purpose of appropriately controlling (delaying separation) according to the frequency of use of the product. For example, if the separation of the two layers after shaking is completed in a very short time of several minutes to within 10 minutes, consumers will need to shake the product many times during use for the purpose of homogenization, and this cumbersome behavior tends to lead to dissatisfaction. Therefore, it is preferable for the separation to occur within 15 minutes to 6 hours, more preferably within 15 minutes to 2 hours. In other words, it is recommended to appropriately add a water-soluble polymer thickener, with separation within about 2 hours as a guideline. In addition, a water-soluble polymer thickener may be added to vary the feeling of use.
In conventional techniques, there are cases where the type of water-soluble polymer thickener that can be selected is limited in a multi-layered cosmetic composition having a two or more layer structure of an emulsion layer and an aqueous layer. For example, in the case of the two-layered liquid cosmetic composition described in Patent Document 8, a water-soluble polymer thickener exhibiting anionic properties is required. However, the multi-layered liquid cosmetic composition of the present invention can use a variety of water-soluble polymer thickeners.
That is, in the present invention, the water-soluble polymer thickener can be any one that is usually contained in cosmetics.Specific examples include polysaccharides, acrylic acid polymers, carboxyvinyl polymers, polyvinyl alcohol, polyvinylpyrrolidone, and derivatives thereof.In particular, polysaccharides and acrylic acid polymers, and derivatives thereof are preferred.Hydroxyethyl cellulose is a preferred example because it has a good feeling when used.
The water-soluble polymer thickener is appropriately selected depending on the desired viscosity and usability of the cosmetic. When the water-soluble polymer thickener is contained, the amount of the water-soluble polymer thickener is 0.01 to 2% by mass, preferably 0.05 to 1% by mass, and more preferably 0.1 to 0.5% by mass, based on the cosmetic.

In addition, it has been pointed out that when a conventional two-layer liquid cosmetic composition consisting of an emulsion layer and an aqueous layer contains a moisturizing agent or humectant such as 1,3-butylene glycol (BG), dipropylene glycol (DPG), 1,2-pentanediol, or ethylhexylglycerin, the polarity of the aqueous layer changes, and emulsion particles tend to remain in the aqueous layer, which causes turbidity and impairs the aesthetic appearance.On the other hand, the two-layer cosmetic composition consisting of an emulsion layer and an aqueous layer of the present invention has a significantly high effect of suppressing the turbidity of the aqueous layer after separation, so that even if it contains a moisturizing agent or humectant such as BG, DPG, or 1,2-pentanediol, the aqueous layer does not become turbid.Therefore, there is no particular restriction on the blending of moisturizing agent or humectant components in the cosmetic composition of the present invention.
When a moisturizing agent or humectant such as BG, DPG, 1,2-pentanediol, or ethylhexylglycerin is contained, the content is adjusted appropriately taking into consideration the feeling when used, and the content is preferably 0.1 to 30% by mass, preferably 1 to 25% by mass, more preferably 3 to 20% by mass, and even more preferably 3 to 15% by mass, based on the cosmetic of the present invention.

The content of water in the cosmetic composition of the present invention may be any amount that can form a multi-layered state. In order to improve re-separation and re-dispersibility, the content is preferably 30% by mass or more, more preferably 40 to 90% by mass, and even more preferably 60 to 85% by mass.

The pH of the cosmetic of the present invention is preferably 4.0 to 10.5 in an environment of 25°C. This range is preferable because it causes less irritation to the skin.

The cosmetic of the present invention can be produced by commonly used production techniques. That is, surfactants (component (A), component (B)), optional components such as water-soluble salts, water-soluble polymer thickeners, moisturizers, and other water-soluble additives are added to water, stirred and dissolved, and heated and stirred and dissolved as necessary to prepare an aqueous layer. Meanwhile, oils, oily substances, and other oil-soluble additives are stirred and dissolved, and heated and stirred and dissolved as necessary to prepare an oil layer. Next, the oil layer is added to the aqueous layer, mixed, and stirred and mixed with a homomixer or the like to prepare a solution in which all components are uniformly dispersed and emulsified. This is filled into an appropriate cosmetic container and left to stand at room temperature, whereby the emulsion layer and aqueous layer are separated, and the cosmetic of the present invention can be obtained.

When left to stand, the multi-layered cosmetic of the present invention maintains a layer-separated state showing a clear boundary between a cloudy emulsion layer and an aqueous layer, and when gently shaken when in use, it easily becomes a cloudy emulsion state as a whole, and after use, it returns to its original multi-layered separated state in a short time. Note that the cosmetic of the present invention may have an emulsion layer as the upper layer and a clear aqueous layer as the lower layer, or vice versa.

The features of the cosmetic of the present invention will be specifically described by showing the cosmetic of the examples and the cosmetic of the comparative example.
<Examples 1 to 2, Comparative Examples 1 to 7>
Two-layered lotion-type cosmetic compositions were prepared in Examples 1 and 2 and Comparative Examples 1 to 7. Each cosmetic composition was produced by a conventional method according to the formulation (unit: mass%) shown in the table.
Examples 1 and 2 contain components (A), (B) and (C).
On the other hand, Comparative Examples 1 to 4 and 7 are examples of compositions that do not contain component (A), and Comparative Example 1 is an example of a composition in which a surfactant having a small average added mole number of oxyethylene groups is blended in place of component (A).
Comparative Examples 2 to 4 and 7 are examples of compositions in which the amount of component (B) was increased in place of component (A).
Comparative Examples 5 and 6 are examples of compositions that do not contain component (B) and have an increased amount of component (A).
The two-layer cosmetic compositions of Examples 1 and 2 and Comparative Examples 1 to 7 were used to carry out the following tests.

1. Evaluation Tests of Examples 1 and 2 and Comparative Examples 1 to 7 (Evaluation Test 1)
1) Evaluation test method Immediately after preparation, 100 mL of the two-layered lotion-type cosmetic compositions of Examples 1 and 2 and Comparative Examples 1 to 7 were filled into a screw-capped glass bottle with a diameter of 4.5 cm and a capacity of 125 mL. The filled cosmetic composition was shaken and stirred 30 times at a width of 20 cm to homogenize the entire cosmetic composition, and then the following items were evaluated. In the composition of these test products, the aqueous layer was the lower layer in all cases.

(1) pH Measurement Immediately after preparation, the pH was measured by the glass electrode method.

(2) Separation Speed After filling into a glass bottle, the bottle was allowed to stand, and the interface where the emulsion layer and the aqueous layer separated was visually observed after 1 hour and 2 hours. The separation speed was evaluated according to the following criteria.
(Evaluation Criteria)
○: Separated into two layers with a clear interface. △: Separated into two layers, but the interface is slightly unclear. ×: Not separated, or separated, but the interface is unclear.

(3) Appearance of Aqueous Layer After Separation After standing for 2 hours, the appearance of the separated aqueous layer was evaluated according to the following criteria.
(Evaluation Criteria)
○: Almost no turbidity △: Slight turbidity ×: Obvious turbidity

(4) Redispersibility After complete separation by standing, the redispersibility when the mixture was shaken again five times at a width of 20 cm was evaluated according to the following criteria.
(Evaluation Criteria)
○: Uniformly redispersed ×: Not uniformly redispersed

(5) Stability over Time In order to confirm the stability over time of the emulsion layer, the emulsion layer was stored at room temperature for 0.5 month and 1 month, and in a thermostatic chamber at 50° C. for 0.5 month and 1 month, and the change in appearance was evaluated according to the following criteria.
In the following evaluation criteria, "separated" refers to a state in which the oil in the emulsion layer separates after standing, and "solidified" refers to a state in which the emulsion layer is partially or entirely solidified after standing and has no fluidity.
(Evaluation Criteria)
○: No problem (no separation or solidification)
△: Very slight separation or slight decrease in fluidity and tendency to solidify. ×: Obvious separation or obvious solidification occurred.

(6) Usability (sensory evaluation)
Five trained sensory evaluators washed the inside of the forearm, applied 0.5 g of the sample, and evaluated the feel upon and after application according to the following criteria. The evaluation judgment was determined by consensus among the five evaluators.
・When applied (freshness)
(Evaluation Criteria)
○: Feels fresh ×: Does not feel fresh - After application (emollient feeling)
(Evaluation Criteria)
○: Has an emollient feeling (moisturizing feeling) ×: Does not have an emollient feeling (moisturizing feeling)

2) Evaluation Results The evaluation test results are shown in the lower part of Table 1.

(1) pH Measurement The pH of the cosmetics of Examples 1 and 2 and Comparative Examples 1 to 7 was measured immediately after preparation by the glass electrode method. There was no significant difference between the cosmetics of the Examples and Comparative Examples. All of the cosmetics were adjusted to a pH suitable for use as cosmetics.

(2) Separation rate (A) Appearance after 1 hour Examples 1 and 2 and Comparative Examples 2 to 7 were rated as "○", i.e., the sample separated into two layers with a clear interface. Comparative Example 1 was rated as "△", i.e., the sample separated into two layers with a slightly unclear interface.
In this test, no cosmetic product was rated as "X".
(B) Appearance after 2 hours The appearance after 2 hours was observed to be the same as that after 1 hour. Examples 1 and 2 and Comparative Examples 2 to 7 were rated as "○" (separated into two layers with a clear interface), and Comparative Example 1 was rated as "△" (separated into two layers, but the interface was somewhat unclear). Even after the passage of time, the composition of Comparative Example 1 did not receive the "○" rating (separated into two layers with a clear interface), but remained rated as "△", which was not the appearance desired by the present invention.

(3) Appearance of the aqueous layer after separation (observation after 2 hours)
Examples 1 and 2 were almost free of turbidity and were rated as "○". Comparative Examples 2 to 4 and 7 were observed to be turbid and were rated as "×", and Comparative Example 5 was observed to be slightly turbid and was rated as "△". Comparative Examples 1 and 6 were almost free of turbidity and were rated as "○", but the other evaluation items were rated as "×", and did not meet the quality required by the present invention.

(4) Redispersibility In Examples 1 and 2, the redispersibility after separation was good. In Comparative Examples 5 and 6, the redispersibility was evaluated as "x" because the particles were not uniformly dispersed. In Comparative Examples 1 to 4 and 7, the redispersibility was good, but the other evaluation items were evaluated as "x", and the quality was not as required by the present invention.

(5) Stability over time In Examples 1 and 2, there was no problem with the emulsion layer after storage for 0.5 and 1 month under each of the conditions of room temperature and 50°C, and the evaluation was "good". On the other hand, in Comparative Examples 1 and 2, clear separation occurred at room temperature or 50°C, and the evaluation was "poor". Furthermore, in Comparative Examples 5 and 6, clear solidification occurred at 50°C, and the evaluation was "poor". In Comparative Examples 5 and 6, a slight decrease in fluidity and a tendency to solidify were observed under room temperature conditions.

(6) Usability (sensory evaluation)
In Examples 1 and 2, both the evaluation items of freshness upon application and emollient feeling after application were rated as "good". On the other hand, in Comparative Examples 1 to 4 and 7, either one of the evaluation items of freshness upon application or emollient feeling after application was rated as "bad". In Comparative Examples 5 and 6, both evaluation items were rated as "good", but the other evaluation items were rated as "bad", which did not meet the quality required by the present invention.

The mass ratio of component (A) to component (B) contained in the cosmetics of Examples 1 and 2 was 1:3.1 in both cases.

(7) Overall Evaluation Examples 1 and 2 of the present invention showed excellent results in all items (separation speed, lack of turbidity in the aqueous layer after separation, redispersibility, stability over time, and feeling when used (freshness, emollient feeling)). On the other hand, Comparative Examples 1 to 7 were rated as "x" in two or more of the evaluation items, and did not achieve the desired quality.
It was believed that a composition not containing either component (A) or component (B) would be undesirable as a cosmetic composition consisting of an emulsion layer and an aqueous layer.

<Examples 3 to 8, Comparative Examples 8 to 16>
Two-layered lotion-type cosmetic compositions were prepared in Examples 3 to 8 and Comparative Examples 8 to 16. Each cosmetic composition was produced in the same manner according to the formulation (unit: mass %) shown in Table 2.
Examples 3 to 8 are compositions according to the present invention.
On the other hand, Comparative Examples 8 to 16 are examples of compositions that do not contain component (A).
Comparative Examples 8 to 16 have compositions in which PEG-8 distearate (HLB 6), PEG-12 diisostearate (HLB 8), and PEG-20 dilaurate (HLB 12) are blended in place of component (A). All of these are polyoxyethylene fatty acid diesters, but are compounds in which the average number of moles of oxyethylene groups added is less than 50.
In the present invention, polyoxyethylene fatty acid diesters having an average added mole number of oxyethylene groups of less than 50 are not a substitute for component (A), but their incorporation is not excluded.
The two-layer cosmetic compositions of Examples 3 to 8 and Comparative Examples 8 to 16 were used to carry out the following tests.

2. Evaluation Tests of Examples 3 to 8 and Comparative Examples 8 to 16 (Evaluation Test 2)
1) Test Method Evaluation tests were carried out using the cosmetics of the Examples and Comparative Examples. The evaluation tests were carried out in the same manner as in (Evaluation Test 1) described above.

2) Test Results The evaluation test results are shown in the lower part of Table 2 below.

(1) pH Measurement The pH of the cosmetics of Examples 3 to 8 and Comparative Examples 8 to 16 was measured immediately after preparation by the glass electrode method. There was no significant difference between the cosmetics of Examples 3 to 8 and Comparative Examples 8 to 16. All of the cosmetics were adjusted to a pH suitable for use as cosmetics.

(2) Separation speed (A) Appearance after 1 hour Examples 4 to 8 and Comparative Examples 8 to 16 were rated as "○", that is, the mixture was separated into two layers with a clear interface. Example 3 was rated as "△" after 1 hour, that is, the mixture was separated into two layers with a slightly unclear interface. However, as will be described later, Example 3 was rated as "○" after 2 hours. Since the interface became clear after about 2 hours, it was determined that the level was acceptable for consumer use.
Furthermore, no compositions rated "x" were observed.
(B) Appearance after 2 hours The observation results after 2 hours were all rated as "good".

(3) Appearance of the aqueous layer after separation (observation after 2 hours)
Examples 3, 5, 6, and 8 were rated as "○" because almost no turbidity was observed, while Examples 4 and 7 were rated as "△" because slight turbidity was observed, whereas Comparative Examples 8 to 16 were rated as "×" because obvious turbidity was observed.

(4) Redispersibility The redispersibility after separation was good in Examples 3 to 8 and Comparative Examples 8 to 13, 15, and 16. Comparative Example 14 was not evaluated because separation of oil (three-layer separation) occurred immediately after separation into two layers.

(5) Stability over time
Examples 3 to 8 were rated "good" without any problems when stored at room temperature and at 50°C (0.5 month, 1 month). On the other hand, Comparative Examples 9, 13, and 14 were rated "poor" because separation occurred when stored at room temperature and at 50°C. Comparative Example 11 was rated "poor" because separation occurred when stored at 50°C. Comparative Example 8 was rated "poor" because separation was observed when stored at room temperature.
It was confirmed that the emulsion layer becomes stable over time by adopting the composition of the present invention.

(6) Usability (sensory evaluation)
In Examples 3 to 8, both the evaluation items of freshness upon application and emollient feeling after application were rated as "good." On the other hand, in Comparative Examples 8 to 16, the evaluation of freshness upon application was "good," but the evaluation of emollient feeling after application was all rated as "poor."

The mass ratio of component (A) to component (B) contained in the cosmetics of Examples 3 to 8 was in the range of 1:1 to 1:19.

(7) Overall Evaluation In Evaluation Test 2, Examples 3 to 8 of the present invention showed excellent results in all items. On the other hand, Comparative Examples 8 to 16, which did not contain Component (A), were all rated as "x" for the transparency of the water layer, and further, in the evaluation of the feeling of use, all of the emollient feeling after application was rated as "x". Thus, Comparative Examples 8 to 16 were judged to be unfavorable in terms of both appearance and feeling of use.
In other words, it was found that even if a compound which is a polyoxyethylene fatty acid diester but has an average added mole number of less than 50 oxyethylene groups is contained in place of component (A), the transparency of the aqueous layer and the feeling when used are not improved.

<Examples 9 to 17, Comparative Examples 17 to 19>
Two-layered lotion-type cosmetic compositions were prepared in Examples 9 to 17 and Comparative Examples 17 to 19. Each cosmetic composition was produced in the same manner according to the formulation (unit: mass %) shown in Table 3.
Examples 9 to 17 contain PEG-150 distearate (HLB 16.5) as component (A), and contain one or two of PEG-60 hydrogenated castor oil (HLB 14), (C12-14) pareth-12 (HLB 14.5), polysorbate 60 (HLB 14.9), PEG-20 glyceryl stearate (HLB 14), laureth-15 (HLB 14), laureth-12 (HLB 13), laureth-10 (HLB 12), and laureth-9 (HLB 12) as component (B), and contain squalane and cetyl ethylhexanoate as component (C). Comparative Examples 17 to 19 are compositions containing a nonionic surfactant with an HLB of 11 to 8 instead of the nonionic surfactant with an HLB of 12 or more as component (B).
The two-layer cosmetic compositions of Examples 9 to 17 and Comparative Examples 17 to 19 were used to carry out the following evaluation tests.

3. Evaluation Tests of Examples 9 to 17 and Comparative Examples 17 to 19 (Evaluation Test 3)
1) Test Method Evaluation tests were carried out using the cosmetics of Examples 9 to 17 and Comparative Examples 17 to 19. The evaluation tests were carried out in the same manner as in (Evaluation Test 1) described above.

2) Test Results The evaluation test results are shown in the lower part of Table 3 below.

(1) pH Measurement The pH of Examples 9 to 17 and Comparative Examples 17 to 19 was measured immediately after preparation using the glass electrode method. There was no significant difference between the cosmetics of the Examples and Comparative Examples. All of the cosmetics were adjusted to a pH suitable for use as cosmetics.

(2) Separation speed (A) Appearance after 1 hour In Examples 10 and 14 to 16, the evaluation after 1 hour was all rated as "○", that is, the mixture was separated into two layers with a clear interface. In Examples 9, 11 to 13 and 17, the evaluation after 1 hour was rated as "△", that is, the mixture was separated into two layers with a slightly unclear interface. However, as will be described later, in Examples 9, 11 to 13 and 17, the evaluation after 2 hours was rated as "○". Since the interface became clear in about 2 hours, it was determined that the level was not problematic for consumer use.
On the other hand, Comparative Examples 17 and 18 were rated as "X", and Comparative Example 19 was rated as "△". As will be described later, Comparative Example 19 remained rated as "△" even after 2 hours had passed, and did not achieve the desired quality. Note that Comparative Example 19 was also observed after 24 hours had passed, but remained rated as "△".
(B) Appearance after 2 hours The observation results after 2 hours were all rated as "good" for Examples 9 to 17.
Moreover, all of Comparative Examples 17 to 19 were rated as "Fair."

(3) Appearance of the aqueous layer after separation (at the time when the aqueous layer was left to stand for 2 hours after shaking) All of Examples 9 to 17 and Comparative Examples 17 to 19 were rated as "◯" with almost no turbidity.

(4) Redispersibility All of Examples 9 to 17 and Comparative Examples 17 to 19 were rated as "◯", indicating favorable redispersibility.

(5) Stability over time
Examples 9 to 17 were rated as "good" because there were no problems when stored at room temperature and at 50° C. On the other hand, Comparative Examples 17 and 18 were rated as "poor" because solidification occurred when stored at 50° C. In this way, it was confirmed that the emulsion layer of all of Examples 9 to 17 was stable over time.

(6) Usability (sensory evaluation)
In Examples 9 to 17, both the evaluation items of freshness upon application and emollient feeling after application were rated as "good." In Comparative Examples 17 to 19, both evaluation items were rated as "good," but the other evaluation items did not meet the desired quality.

The mass ratio of component (A) to component (B) contained in the cosmetics of Examples 9 to 17 was in the range of 1:3.1 to 1:7.

(7) Overall Evaluation In Evaluation Test 3, Examples 9 to 17 of the present invention showed excellent results in all evaluation items. On the other hand, Comparative Examples 17 and 18 were rated as "X" for stability over time at 50°C. Thus, Comparative Examples 17 and 18 were determined to have compositions that were not preferable in terms of stability over time. Furthermore, Comparative Examples 17 to 19 remained rated as "△" even after 2 hours had passed in the evaluation of the separation speed (visual observation), and were therefore determined to be unfavorable.

From the results of the evaluation tests of the two-layer liquid cosmetics consisting of an emulsion layer and an aqueous layer in Examples 1 to 17 and Comparative Examples 1 to 19 shown in Tables 1 to 3, it was concluded that in order to obtain a cosmetic that has an appropriate separation speed after mixing by shaking, a clear aqueous layer without turbidity after separation, a fresh feeling when applied and an excellent emollient feeling after application, and good storage stability, it is necessary to contain the oil agent of component (C), as well as components (A) and (B).

The composition of the present invention not only provides a good sensation during application, such as a fresh feeling, and an emollient feeling after application, but also provides excellent redispersibility, separation speed after shaking and standing (the boundary of the interface becomes clear after about 2 hours), and transparency of the water layer (no turbidity), resulting in a two-layer liquid cosmetic with a beautiful appearance as a cosmetic. In particular, when the mass ratio of component (A) to component (B) contained in the cosmetic is in the range of (A):(B) = 1:1 to 1:20, all evaluation items are good, eliminating the need for complicated trial and error during formulation design and development. Furthermore, the excellent effects of the present invention can be obtained even if a water-soluble polymer thickener or moisturizer is optionally blended, making it possible to vary the formulation.

Claims (1)

A multi-layered liquid cosmetic preparation comprising the following components (A) to (C) , wherein the mass ratio of the following component (A) to the following component (B) is (A):(B)=1:1 to 1:20 .
(A) 0.01 to 0.4% by mass of a polyoxyethylene fatty acid diester having an average number of moles of oxyethylene groups added of 50 to 300, including at least one selected from PEG-150 distearate, PEG-75 dilaurate, PEG-190 distearate, and PEG-250 distearate , relative to the total amount of the multi-layered liquid cosmetic
(B) A nonionic surfactant different from component (A) and having an HLB of 12 or more. (C) An oil agent that is liquid at 25°C.