Base for water-in-oil type emulsion cosmetic and water-in-oil type emulsion cosmetic containing said base

Abstract

To provide: a novel base agent which is capable of thickening a water-in-oil emulsion cosmetic composition that contains a silicone oil; and a water-in-oil emulsion cosmetic composition containing a silicone oil, the water-in-oil emulsion cosmetic composition being thickened with the base agent.SOLUTION: A base agent for water-in-oil emulsion cosmetic compositions according to the present disclosure contains a silicone oil, a polar oil and an oil-soluble copolymer which has a monomer unit that is composed of a specific hydrophilic monomer and a monomer unit that is composed of a specific hydrophobic monomer.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a water-in-oil emulsion cosmetic. [Background technology]

[0002] For example, in the field of cosmetics, water-in-oil emulsion cosmetics that can impart not only oil and oil-soluble components but also moisture and water-soluble components to the skin are used. In order to improve the usability of cosmetics, attempts to thicken or gel water-in-oil emulsion cosmetics have been studied.

[0003] Patent Document 1 discloses a water-in-oil emulsion sunscreen cosmetic that contains (A) 6 to 40 mass % of an ultraviolet absorber, (B) an organically modified clay mineral such as bentone, (C) 0.1 to 15 mass % of an oil phase thickener other than (B), (D) 0.1 to 8 mass % of a silicone surfactant having an HLB of less than 8, (E) a spherical resin powder, and (F) a volatile silicone oil, and the ratio of [total amount of components (B) and (C)] / [total amount of non-volatile liquid oil other than (G) silicone oil] is 0.04 or more and less than 0.68.

[0004] Patent Document 2 discloses a water-in-oil emulsion cosmetic that contains an oil-based gelling agent made of a copolymer composed of a specific hydrophobic monomer and a specific hydrophilic monomer, and an oil component such as a hydrocarbon oil.

[0005] Patent Document 3 discloses a water-in-oil emulsion cosmetic containing an oil thickener for cosmetics consisting of a copolymer composed of an easily crystallizable hydrophobic monomer, a poorly crystallizable hydrophobic monomer, and a hydrophilic monomer, and an oil component such as a hydrocarbon oil. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-210492 A [Patent Document 2] International Publication No. 2016 / 098456 [Patent Document 3] JP 2019-206515 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the case of thickening silicone oils, organically modified clay minerals such as bentones as described in Patent Document 1 have generally been used.

[0008] It is known that copolymers composed of specific monomers described in Patent Documents 2 and 3 can be used as oil-based gelling agents or oil thickening agents, but such copolymers have low compatibility with silicone oil and are therefore not typically used as thickening agents or gelling agents in water-in-oil emulsion cosmetics containing silicone oil.

[0009] For this reason, there has been a demand for an increase in the variety of thickening agents that include silicone oils so that they can be used in a variety of cosmetic compositions.

[0010] Therefore, an object of the present disclosure is to provide a novel base capable of thickening a water-in-oil emulsion cosmetic containing a silicone oil, and a water-in-oil emulsion cosmetic containing a silicone oil thickened using the base. [Means for solving the problem]

[0011] <Aspect 1> Silicone oil, Polar oils, as well as An oil-soluble copolymer having a monomer unit composed of at least one hydrophilic monomer selected from the following formulas 1 and 2, and a monomer unit composed of a hydrophobic monomer represented by the following formula 4: Including, Water-in-oil emulsion cosmetic base: [ka] In formula 1, R 1 is a hydrogen atom, a glyceryl group, a linear or branched hydroxyalkyl group having 1 to 4 carbon atoms, or -(CHO) n H, where n is an integer from 2 to 10; and R 2 is a hydrogen atom or a methyl group, [ka] In formula 2, R 3 is a hydrogen atom or a methyl group, and R 4 is a linear or branched alkyl or hydroxyalkyl group having 1 to 4 carbon atoms, or a substituent of the following formula 3: [ka] [ka] In formula 4, R 5 is a linear or branched alkyl group having 16 to 22 carbon atoms, and R 6 is a hydrogen atom or a methyl group. <Aspect 2> The base according to embodiment 1, wherein the monomer of formula 1 is at least one selected from 2-hydroxyethyl (meth)acrylate, glyceryl (meth)acrylate, PPG-6 (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-2-methylpropyl (meth)acrylate, and (meth)acrylic acid, and the monomer of formula 2 is at least one selected from N-(2-hydroxyethyl)(meth)acrylamide, N-isopropyl(meth)acrylamide, and 2-(meth)acrylamido-2-methylpropanesulfonic acid. <Aspect 3> The base according to aspect 1 or 2, wherein the monomer of formula 4 is at least one selected from cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate. <Aspect 4> The base material according to any one of aspects 1 to 3, wherein the oil-soluble copolymer contains monomer units of the hydrophilic monomer in an amount of 30 to 50 mol % and monomer units of the hydrophobic monomer in an amount of 50 to 70 mol %. <Aspect 5> The base according to any one of aspects 1 to 4, wherein the silicone oil is at least one selected from dimethyl silicone, methylphenyl polysiloxane, and cyclic polysiloxane. Aspect 6 The base material according to any one of aspects 1 to 5, wherein the polar oil has an IOB value of 0.10 or more. Aspect 7 7. The base of claim 6, wherein the polar oil is at least one selected from octyl methoxycinnamate, tripropylene glycol dipivalate, cetyl ethylhexanoate, diisostearyl malate, and octyl salicylate. <Aspect 8> The base according to any one of aspects 1 to 7, wherein the silicone oil is contained in an amount of 50% by mass or more. <Aspect 9> A base according to any one of aspects 1 to 8, wherein the mass ratio of the silicone oil to the polar oil is from 9:1 to 4:1. Aspect 10 A base according to any one of aspects 1 to 9, which thickens upon the addition of water. <Aspect 11> A base according to any one of aspects 1 to 10, Droplets dispersed in the base and containing water; Including, Water-in-oil emulsion cosmetics. Aspect 12 A cosmetic preparation according to aspect 11, wherein the content of the oil-soluble copolymer is 0.1% by mass or more. Aspect 13 13. The cosmetic preparation according to aspect 11 or 12, wherein the silicone oil is contained in an amount of 10% by mass or more. Aspect 14 14. The cosmetic preparation according to any one of aspects 11 to 13, further comprising a pigment. Aspect 15 The cosmetic preparation according to embodiment 14, which is used as a foundation. Effect of the Invention

[0012] According to the present disclosure, it is possible to provide a novel base capable of thickening a water-in-oil emulsion cosmetic containing a silicone oil, and a water-in-oil emulsion cosmetic containing a silicone oil thickened using the base. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1(a) is a schematic diagram of a base in which the oil-soluble copolymer of the present disclosure is blended in a continuous phase composed of silicone oil, and FIG. 1(b) is a schematic diagram of a water-in-oil emulsion cosmetic prepared by adding water to the base of FIG. [Diagram 2] FIG. 1(a) is a schematic diagram of a base in which the oil-soluble copolymer of the present disclosure is blended into a continuous phase composed of silicone oil and polar oil, and FIG. 1(b) is a schematic diagram of a water-in-oil emulsion cosmetic prepared by adding water to the base of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure is not limited to the following embodiments, and may be modified in various ways within the scope of the present invention.

[0015] The base for water-in-oil emulsion cosmetics of the present disclosure (sometimes simply referred to as the "base") contains a silicone oil, a polar oil, and an oil-soluble copolymer having monomer units composed of at least one hydrophilic monomer selected from formula 1 and formula 2 above, and monomer units composed of a hydrophobic monomer of formula 4 above.

[0016] Although not limited by the theory, the principle of action of adding water to a base containing silicone oil to obtain a thickened water-in-oil emulsion cosmetic is believed to be as follows.

[0017] It is known that the oil-soluble copolymer of the present disclosure can cause gelation, a type of thickening, in hydrocarbon oils such as liquid paraffin and ester oils such as 2-ethylhexanoate, as described in Patent Document 2. However, as described in Patent Document 2, this oil-soluble copolymer has low compatibility with silicone oils, and therefore, when this oil-soluble copolymer is blended with silicone oil such as dimethylpolysiloxane, for example, precipitation of only the polymer of the oil-soluble copolymer 11 tends to occur, as shown in FIG. 1(a).

[0018] When water is added to a base containing such an oil-soluble copolymer in a precipitated state and silicone oil, the precipitated state can be eliminated and an emulsion can be obtained, but the resulting water-in-oil emulsion cosmetic is not thickened and has a smooth state, and is in an unstable emulsion state that immediately separates when left to stand. This is because the oil-soluble copolymer has a portion composed of a specific hydrophilic monomer, and it is considered that the oil-soluble copolymer 11 is arranged near the interface between the water phase (water droplets 13) and the oil phase, as shown in (b) of Figure 1. On the other hand, the portion composed of a specific hydrophobic monomer is difficult to spread in silicone oil, which is difficult to dissolve, and it is difficult to form a network structure that incorporates oil by such a portion, so it is considered that the oil-soluble copolymer of the present disclosure is difficult to thicken the water-in-oil emulsion cosmetic containing silicone oil.

[0019] The base of the present disclosure contains polar oil in addition to silicone oil.This polar oil is easily compatible with the part of oil-soluble copolymer that is composed of a specific hydrophobic monomer, but for example, even if oil-soluble copolymer and polar oil are blended in oil that contains a high amount of silicone oil, the thickening effect of the base is poor, just like the case of silicone oil alone, and in some cases, a gel or swollen layer that contains part of oil is formed.However, the present inventor has unexpectedly found that when water is added to such base to prepare a water-in-oil emulsion cosmetic, this cosmetic can exhibit thickening properties.

[0020] In a base containing silicone oil and polar oil, the portion of the oil-soluble copolymer composed of a specific hydrophobic monomer is more likely to spread in the oil phase than in a base containing only silicone oil as the oil phase, so even in the area where the oil-soluble copolymer 21 is precipitated as shown in Figure 2 (a), some oil is taken in, and a gel or swollen layer is formed, which may cause local thickening, but it is thought that such a thickening effect does not contribute to the thickening of the entire base. On the other hand, when water is added to emulsify, the emulsified water droplets are dispersed throughout the system, and the oil-soluble copolymer located near the interface between the water phase and the oil phase is also dispersed throughout the system. Furthermore, it is believed that the portion of the oil-soluble copolymer that is composed of a specific hydrophobic monomer spreads more easily into the oil phase when the oil phase contains silicone oil and a polar oil than when the oil phase contains only silicone oil, and as a result, as shown in Figure 2(b), the portion composed of the specific hydrophobic monomer that has spread around the water droplets 23 forms a network structure throughout the system with the water droplets 23 as cross-linking points, thereby retaining the oil, and thus thickening the water-in-oil emulsion cosmetic that contains silicone oil.

[0021] Furthermore, in a water-in-oil emulsion cosmetic prepared using the base of the present disclosure, in addition to an increase in viscosity, the hydrophobic monomer units present in a manner that spreads throughout the oil phase act as steric hindrances, suppressing the coalescence of adjacent water droplets, and it is believed that this improves the emulsion stability of the cosmetic.

[0022] The definitions of terms used in this disclosure are as follows:

[0023] In the present disclosure, the term "hydrophilic monomer" refers to a monomer that dissolves in any proportion in water, and the term "hydrophobic monomer" refers to any other monomer, i.e., a monomer that is essentially immiscible in water.

[0024] In the present disclosure, "(meth)acrylic" means acrylic or methacrylic.

[0025] <Base for water-in-oil type emulsion cosmetics> The water-in-oil emulsion cosmetic base of the present disclosure contains a silicone oil, a polar oil, and an oil-soluble copolymer having monomer units composed of at least one hydrophilic monomer selected from the above-mentioned formula 1 and formula 2, and monomer units composed of a hydrophobic monomer of the above-mentioned formula 4, and has the ability to thicken when water is added.

[0026] <Silicone oil> The amount of silicone oil in the base of the present disclosure is not particularly limited, and can be, for example, 50% by mass or more, 55% by mass or more, or 60% by mass or more relative to the total amount of the base, and can be 80% by mass or less, 75% by mass or less, or 70% by mass or less.

[0027] Alternatively, the amount of silicone oil can be, for example, greater than the amount of polar oil blended at the same time; specifically, it can be 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, or 75% by mass or more relative to the total amount of oil, and can be 95% by mass or less, 90% by mass or less, or 85% by mass or less.

[0028] The silicone oil is not particularly limited, and examples thereof include dimethyl silicone (sometimes referred to as "dimethyl polysiloxane" or "dimethicone"); methyl phenyl polysiloxanes such as trimethyl pentaphenyl trisiloxane, diphenyl dimethicone, diphenyl siloxy phenyl trimethicone, phenyl trimethicone, and phenyl dimethicone (sometimes referred to as "methyl phenyl silicone"); cyclic polysiloxanes such as octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, and dodecamethyl cyclohexasiloxane (sometimes referred to as "cyclic silicone"); methyl hydrogen polysiloxane; and perfluorooctylethyl / diphenyl dimethicone. These can be used alone or in combination of two or more. Among these, from the viewpoints of thickening properties, emulsion stability, and the like, at least one selected from dimethyl silicone, methylphenyl polysiloxane, and cyclic polysiloxane is preferred, and furthermore, from the viewpoints of makeup durability or, for example, separation resistance (cracking resistance) when the cosmetic is formulated as a liquid foundation, and the like, dimethyl silicone is more preferred.

[0029] <Polar oil> When the base contains only silicone oil as oil, it cannot be significantly thickened even if it is combined with the oil-soluble copolymer of the present disclosure and water is added.In other words, the polar oil that is mixed into the base of the present disclosure can function as a binder component to thicken silicone oil and oil-soluble copolymer.

[0030] The amount of polar oil to be blended is not particularly limited, and can be, for example, 5.0 mass% or more, 10 mass% or more, or 15 mass% or more relative to the total amount of the base, and can be 30 mass% or less, 25 mass% or less, or 20 mass% or less.

[0031] Alternatively, the amount of polar oil can be, for example, 5.0 mass% or more, 10 mass% or more, or 15 mass% or more relative to the total amount of oil, and can be 45 mass% or less, 40 mass% or less, 35 mass% or less, 30 mass% or less, or 25 mass% or less.

[0032] The blending ratio of the silicone oil to the polar oil is not particularly limited, but from the viewpoint of emulsion stability, for example, resistance to separation (cracking resistance) when the cosmetic is formulated as a liquid foundation, the mass ratio of the silicone oil to the polar oil is preferably in the range of 9:1 to 4:1 (8:2), more preferably in the range of 9:1 to 8.5:1.5.

[0033] The polar oil to be blended in the base of the present disclosure is not particularly limited as long as it can function as a binder component for thickening, and for example, a polar oil with an IOB value of 0.10 or more can be used.

[0034] The IOB value of the polar oil can be, for example, 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, or 0.15 or more, and can be 0.65 or less, 0.60 or less, 0.55 or less, 0.50 or less, 0.45 or less, or 0.40 or less. In particular, from the viewpoint of long-term viscosity increase performance or emulsion stability performance, the IOB value of the polar oil is preferably 0.15 or more and 0.55 or less, more preferably 0.20 or more and 0.55 or less, and particularly preferably 0.20 or more and 0.50 or less.

[0035] Here, the IOB value is an abbreviation of Inorganic / Organic Balance, which is a value that indicates the ratio of inorganic value to organic value, and is an index that indicates the degree of polarity of an organic compound. Specifically, the IOB value is expressed as IOB value = inorganic value / organic value. For each of the "inorganic value" and "organic value", "inorganic value" is set according to various atoms or functional groups, for example, the "organic value" for one carbon atom in a molecule is 20, and the "inorganic value" for one hydroxyl group is 100. By accumulating the "inorganic value" and "organic value" of all atoms and functional groups in an organic compound, the IOB value of the organic compound can be calculated (for example, see "Organic Conceptual Diagram - Basics and Applications" by Yoshio Koda, pp. 11-17, Sankyo Publishing, 1984).

[0036] Examples of polar oils that meet these IOB value requirements are oleic acid (IOB value = 0.42), isostearic acid (IOB value = 0.43), isopropyl myristate (IOB value = 0.18), octyl palmitate (IOB value = 0.13), isopropyl palmitate (IOB value = 0.16), butyl stearate (IOB value = 0.14), hexyl laurate (IOB value = 0.17), myristyl myristate (IOB value = 0.11), decyl oleate (IOB value = 0.11), isononyl isononanoate (IOB value = 0.20), and isopropyl oleate (IOB value = 0.21). Isotridecyl nonanoate (IOB value = 0.15), cetyl ethylhexanoate (IOB value = 0.13), pentaerythrityl tetraethylhexanoate (IOB value = 0.35), diethylhexyl succinate (IOB value = 0.32), glycol distearate (IOB value = 0.16), glyceryl diisostearate (IOB value = 0.29), neopentyl glycol dicaprate (IOB value = 0.25), diisostearyl malate (IOB value = 0.28), trimethylolpropane triisostearate (IOB value = 0.16), triethyl 2-ethyl 1,2-dimethyl 2,3-dimethyl ... Glyceryl hexanoate (triethylhexanoin) (IOB value = 0.35), trimethylolpropane trioctanoate (IOB value = 0.33), trimethylolpropane triisostearate (IOB value = 0.16), diisobutyl adipate (IOB value = 0.46), N-lauroyl-L-glutamic acid-2-octyldodecyl ester (IOB value = 0.29), 2-hexyldecyl adipate (IOB value = 0.16), diisopropyl sebacate (IOB value = 0.40), octyl methoxycinnamate (ethyl methoxycinnamate ) (IOB value = 0.28), olive oil (IOB value = 0.16), castor oil (IOB value = 0.43), decyltetradecanol (IOB value = 0.21), octyldodecanol (IOB value = 0.26), oleyl alcohol (IOB value = 0.28), 2-ethylhexyl palmitate (IOB value = 0.13), 2-ethylhexyl ethylhexanoate (IOB value = 0.2), triisostearin (IOB value = 0.16), tripropylene glycol dipivalate (sometimes called "PPG-3 dipivalate").) (IOB value = 0.52), octyl salicylate (IOB = 0.60), tri(caprylic acid / capric acid)glyceryl (IOB value = 0.33), etc. These can be used alone or in combination of two or more. Among them, from the viewpoint of thickening property, emulsion stability, etc., at least one selected from octyl methoxycinnamate, tripropylene glycol dipivalate, cetyl ethylhexanoate, diisostearyl malate, and octyl salicylate is preferred, and at least one selected from octyl methoxycinnamate, tripropylene glycol dipivalate, and diisostearyl malate is more preferred, and further, from the viewpoint of separation resistance (cracking resistance) when the cosmetic is prepared as a liquid foundation, for example, octyl methoxycinnamate is particularly preferred.

[0037] <Any oil> The oil in the base of the present disclosure may be only silicone oil and polar oil, but may also be optionally mixed with oil other than silicone oil and polar oil within a range that does not affect the effect of the present invention.Such oil may include, for example, hydrocarbon oil, higher alcohol, and oil-soluble polyhydric alcohol.These may be used alone or in combination of two or more.

[0038] Examples of the hydrocarbon oil include liquid paraffin, tetraisobutane, hydrogenated polydecene, olefin oligomer, isododecane, isohexadecane, squalane, and hydrogenated polyisobutene.

[0039] Examples of higher alcohols include isostearyl alcohol and oleyl alcohol.

[0040] An example of the oil-soluble polyhydric alcohol is polybutylene glycol.

[0041] When such an optional oil is blended in the base, the oil can be blended in a range of 15% by mass or less, 10% by mass or less, or 5.0% by mass or less based on the total amount of the base, or 10% by mass or less, 5.0% by mass or less, or 1.0% by mass or less based on the total amount of the oil. There is no particular restriction on the lower limit of the blend amount of the optional oil, but it can be more than 0% by mass or 0.1% by mass or more based on the total amount of the base or oil.

[0042] <Oil-soluble copolymer> The base of the present disclosure contains an oil-soluble copolymer that can function as a thickener in a water-in-oil emulsion cosmetic. Such an oil-soluble copolymer has at least a monomer unit composed of at least one hydrophilic monomer selected from the above formula 1 and formula 2, and a monomer unit composed of a hydrophobic monomer of the above formula 4. Each of these monomer units may be composed of a single monomer unit, or may be composed of two or more types of monomer units. For example, the hydrophilic monomer unit may be composed of one type of monomer unit, and the hydrophobic monomer unit may be composed of two types of monomer units.

[0043] The polymerization form of the oil-soluble copolymer is not particularly limited, and for example, a random type, a block type, etc. can be adopted, but from the viewpoint of ease of synthesis, a random type is preferable.

[0044] The ratio of the monomer unit composed of the hydrophilic monomer and the monomer unit composed of the hydrophobic monomer in the oil-soluble copolymer is not particularly limited, but for example, from the viewpoint of thickening property, emulsion stability, etc., the monomer unit of the hydrophilic monomer may be contained at 30 mol% or more, 32 mol% or more, 35 mol% or more, or 40 mol% or more, and may be contained at 50 mol% or less, 48 ​​mol% or less, or 45 mol% or less. From the viewpoint of thickening property, emulsion stability, solubility in oil, etc., the monomer unit of the hydrophobic monomer may be contained at 50 mol% or more, 52 mol% or more, or 55 mol% or more, and may be contained at 70 mol% or less, 68 mol% or less, 65 mol% or less, or 60 mol% or less.

[0045] The content of the oil-soluble copolymer can be 0.1 mass% or more, 0.5 mass% or more, or 1.0 mass% or more, and can be 10 mass% or less, 5.0 mass% or less, or 3.0 mass% or less, based on the total amount of the base.

[0046] The ratio of the oil-soluble copolymer to the total amount of oil can be 0.5 mass% or more, 0.7 mass% or more, 1.0 mass% or more, 1.2 mass% or more, or 1.5 mass% or more, and can be 8.0 mass% or less, 7.0 mass% or less, 6.0 mass% or less, 5.0 mass% or less, 4.5 mass% or less, or 4.0 mass% or less.

[0047] (hydrophilic monomer) As the hydrophilic monomer, at least one monomer selected from the following formula 1 and formula 2 can be used.

[0048] a. Monomer of formula 1 [ka]

[0049] In formula 1, R 1 is a hydrogen atom, a glyceryl group, a linear or branched hydroxyalkyl group having 1 to 4 carbon atoms, or -(CHO) n H, n is an integer from 2 to 10, and R 2 is a hydrogen atom or a methyl group. Examples of the hydroxyalkyl group include a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2-hydroxyethyl-2-methylpropyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group.

[0050] Specific examples of the hydrophilic monomer represented by formula 1 include 2-hydroxyethyl (meth)acrylate, glyceryl (meth)acrylate, PPG-6 (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-2-methylpropyl (meth)acrylate, and (meth)acrylic acid. These can be used alone or in combination of two or more. Among them, from the viewpoint of thickening property, emulsion stability, etc., glyceryl (meth)acrylate is preferred, and glyceryl methacrylate is more preferred.

[0051] b. Monomer of formula 2 [ka]

[0052] In formula 2, R 3 is a hydrogen atom or a methyl group, and R 4 is a linear or branched alkyl or hydroxyalkyl group having 1 to 4 carbon atoms, or a substituent of the following formula 3: [ka]

[0053] Here, R 4 In the above formula, examples of the alkyl group include an ethyl group, a propyl group, an isopropyl group, and a butyl group. Examples of the hydroxyalkyl group include a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2-hydroxyethyl-2-methylpropyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group.

[0054] Specific examples of the hydrophilic monomer represented by formula 2 include N-(2-hydroxyethyl)(meth)acrylamide, N-isopropyl(meth)acrylamide, and 2-(meth)acrylamide-2-methylpropanesulfonic acid. These can be used alone or in combination of two or more. Among them, from the viewpoints of thickening properties, emulsion stability, etc., N-(2-hydroxyethyl)(meth)acrylamide is preferred, and N-(2-hydroxyethyl)acrylamide is more preferred.

[0055] (Hydrophobic Monomer) c. Monomer of formula 4 [ka]

[0056] In formula 4, R 5 is a linear or branched alkyl group having 16 to 22 carbon atoms, and R 6 is a hydrogen atom or a methyl group. Examples of the linear or branched alkyl group having 16 to 22 carbon atoms include a cetyl group, a stearyl group, an isostearyl group, and a behenyl group. Among these, from the viewpoints of thickening properties, emulsion stability, compatibility with polar oils, and the like, linear alkyl groups having 16 to 22 carbon atoms are preferred, and a cetyl group, a stearyl group, and a behenyl group are more preferred.

[0057] Such a hydrophobic monomer is an alkyl (meth)acrylate ester, that is, an ester of (meth)acrylic acid and an alcohol having a linear or branched alkyl group having 16 to 22 carbon atoms. Specific examples include cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and behenyl (meth)acrylate. These can be used alone or in combination of two or more. Among them, from the viewpoints of thickening properties, emulsion stability, compatibility with polar oils, and the like, cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate are preferred, and stearyl (meth)acrylate is more preferred.

[0058] (any monomer) From the viewpoint of thickening and emulsion stability, the oil-soluble copolymer of the present disclosure preferably does not contain monomer units composed of monomers other than those of the above formula 1, formula 2, and formula 4, but may further contain other monomer units within a range that does not impair the effects of the present invention. The proportion of such monomer units can be 30 mol% or less, 20 mol% or less, 15 mol% or less, 10 mol% or less, or 5 mol% or less of the total amount of the constituent monomer units, and can also be more than 0 mol%, 1 mol% or more, or 3 mol% or more.

[0059] Examples of monomers other than those of the above formula 1, formula 2, and formula 4 include one or more monomers selected from the group consisting of various anionic monomers, cationic monomers, nonionic monomers, and other monomers.

[0060] Specifically, examples of hydrophilic monomers other than the hydrophilic monomers represented by Formula 1 or Formula 2 include vinylpyrrolidone, vinylimidazole, methoxypolyethylene glycol (meth)acrylate, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, acryloylmorpholine, methacryloylmorpholine, N-(2-methacryloyloxyethyl)ethyleneurea, and 2-methacryloyloxyethyl phosphorylcholine.

[0061] Examples of hydrophobic monomers other than the hydrophobic monomer represented by formula 4 include methylstyrene, styrene, benzyl (meth)acrylate, phenyl (meth)acrylate, tris(trimethylsiloxy)silylpropyl (meth)acrylate, and 2-perfluorohexyl-2-ethyl (meth)acrylate.

[0062] In addition, a hydrophobic monomer represented by the following formula 5 can be used: [ka]

[0063] In formula 5, R 7 is a branched alkyl group having 18 or less carbon atoms, or a linear alkyl group having 12 or less carbon atoms, and R 8 is a hydrogen atom or a methyl group. 7 The linear or branched alkyl group in may be an alkyl group having 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more carbon atoms. 8 is preferably a hydrogen atom.

[0064] The monomer units composed of the hydrophobic monomers shown in the above formula 4 are thought to crystallize due to the hydrophobic monomer units between the copolymers as the oil-soluble copolymers approach each other, forming a network structure that incorporates oil. On the other hand, the monomer units composed of the hydrophobic monomers shown in formula 5 can inhibit crystallization due to the monomer units composed of the hydrophobic monomers shown in formula 4 and suppress the development of a network structure based on crystallization, so the thickening can be controlled by introducing the monomer units composed of the hydrophobic monomers shown in formula 5.

[0065] Specific examples of the hydrophobic monomer represented by formula 5 include hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, and isostearyl (meth)acrylate. These can be used alone or in combination of two or more. Among them, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, and isostearyl (meth)acrylate are preferred, octyl (meth)acrylate, lauryl (meth)acrylate, and isostearyl (meth)acrylate are more preferred, and octyl (meth)acrylate and isostearyl (meth)acrylate are even more preferred.

[0066] (Method for producing oil-soluble copolymer) The oil-soluble copolymer of the present disclosure can be obtained by a known polymerization method.Not limited to the following method, for example, a mixture of hydrophilic monomer and hydrophobic monomer, a polymerization solvent, and a polymerization initiator are charged into a reaction vessel, and the mixture is heated to maintain a constant temperature for several hours to allow the polymerization reaction to proceed.Then, the polymerization solvent is distilled off from the solution in the reaction vessel to obtain an oil-soluble copolymer.

[0067] Alternatively, the copolymer can be obtained by living radical polymerization, which makes it easy to control the molecular weight of the copolymer and produces a copolymer with a narrow molecular weight distribution.

[0068] d. Polymerization solvent As the polymerization solvent, a solvent that does not show reactivity with the functional group of the monomer is appropriately selected. Examples of the polymerization solvent include, but are not limited to, hydrocarbon solvents such as n-hexane, n-octane, n-decane, isodecane, cyclohexane, methylcyclohexane, toluene, xylene, ethylbenzene, and cumene; alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-hexanol, benzyl alcohol, and cyclohexanol; hydroxyl group-containing glycol ethers such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol propyl ether, butyl carbitol, butyl triethylene glycol, and methyl dipropylene glycol; diglyme, triglyme, methyl cellosolve acetate, propylene glycol monomethyl ether acetate, dipropylene glycol butyl ether acetate, diethylene glycol monomethyl ether acetate, dipropylene ... ether-based solvents such as diethyl ether, dipropyl ether, methyl cyclopropyl ether, tetrahydrofuran, dioxane, and anisole; ketone-based solvents such as dimethyl ketone, diethyl ketone, ethyl methyl ketone, isobutyl methyl ketone, cyclohexanone, isophorone, and acetophenone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, propyl acetate, methyl butyrate, ethyl butyrate, caprolactone, methyl lactate, and ethyl lactate; halogen-based solvents such as chloroform, dichloromethane, dichloroethane, and o-dichlorobenzene; amide-based solvents such as formamide, N,N-dimethylformamide, N,N-dimethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, and ε-caprolactam; dimethyl sulfoxide, sulfolane, tetramethylurea, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, nitromethane, acetonitrile, nitrobenzene, and dioctyl phthalate. These can be used alone or in combination of two or more.

[0069] e. Polymerization initiator The polymerization initiator may be any of those known in the art, and may be, but is not limited to, an organic peroxide or an azo compound. Specifically, benzoyl peroxide, dicumyl peroxide, diisopropyl peroxide, di-t-butyl peroxide, t-butyl peroxybenzoate, t-hexyl peroxybenzoate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyl-3,3-isopropyl hydroperoxide, t-butyl hydroperoxide, dicumyl hydroperoxide, acetyl peroxy, etc. peroxide, bis(4-t-butylcyclohexyl)peroxydicarbonate, isobutyl peroxide, 3,3,5-trimethylhexanoyl peroxide, lauryl peroxide, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)3,3,5-trimethylcyclohexane, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis(isobutyrate), etc. These can be used alone or in combination of two or more kinds.

[0070] f. Polymerization time The time for maintaining the reflux state, i.e., the polymerization time, is preferably such that polymerization is continued until the monomer is exhausted, and is not particularly limited, and can be, for example, 1 hour or more, 2 hours or more, or 3 hours or more, and can be 144 hours or less, 72 hours or less, or 48 hours or less.

[0071] G. Polymerization atmosphere The polymerization atmosphere is not particularly limited, and the polymerization may be performed directly under an air atmosphere, that is, oxygen may be present within a normal range in the polymerization system, or the polymerization may be performed under an inert gas atmosphere such as nitrogen or argon in order to remove oxygen as necessary. The various materials used may be subjected to distillation, activated carbon, alumina, or the like to remove impurities, but commercially available products may be used as they are. The polymerization may also be performed under light-shielded conditions, or in a transparent container such as glass.

[0072] h. Other components that contribute to the polymerization reaction For example, other components such as a chain transfer agent may be added to the reaction vessel as necessary to adjust the molecular weight of the copolymer. Examples of such chain transfer agents include, but are not limited to, compounds having a mercapto group such as lauryl mercaptan and thioglycerol; inorganic salts such as sodium hypophosphite and sodium hydrogen sulfite; and α-methylstyrene dimer. The amount of the chain transfer agent used is appropriately determined so that the molecular weight of the copolymer falls within the desired range, and is usually preferably in the range of 0.01 to 10% by mass relative to the monomer.

[0073] <Water-in-oil emulsion cosmetics> The water-in-oil emulsion cosmetic of the present disclosure contains the above-mentioned base and water droplets that are dispersed in the base and contain water.

[0074] The water-in-oil emulsion cosmetic of the present disclosure contains a polar oil in addition to silicone oil as the oil component of the continuous phase, and contains water droplets of the dispersed phase and the above-mentioned oil-soluble copolymer, and as a result, can exhibit an excellent thickening effect. The thickening property of such a cosmetic can be evaluated by the viscosity measured using a B-type viscometer (TVB-type viscometer TVB-10, manufactured by Toki Sangyo Co., Ltd.) under the measurement conditions of an atmosphere of 25°C, any one of rotors No. 2 to 4, and a rotation speed of 12 rpm.

[0075] In some embodiments, for example, the viscosity of a cosmetic composition of the present disclosure that does not contain a powder such as a pigment when unshaken or after shaking can be 500 mPa·s or more, 600 mPa·s or more, 700 mPa·s or more, 800 mPa·s or more, or 900 mPa·s or more. There is no particular upper limit to the viscosity, but it can be, for example, 30,000 mPa·s or less, 15,000 mPa·s or less, 10,000 mPa·s or less, 5,000 mPa·s or less, or 3,000 mPa·s or less.

[0076] In some embodiments, for example, the viscosity of a cosmetic composition of the present disclosure containing a powder of a pigment or the like before or after shaking can be 4,000 mPa·s or more, 5,000 mPa·s or more, 6,000 mPa·s or more, 7,000 mPa·s or more, 8,000 mPa·s or more, or 9,000 mPa·s or more. There is no particular upper limit to the viscosity, but it can be, for example, 60,000 mPa·s or less, 55,000 mPa·s or less, 50,000 mPa·s or less, or 45,000 mPa·s or less.

[0077] Here, the viscosity of the cosmetic refers to the viscosity at least one of the following times after the cosmetic is prepared: on the same day (e.g., 1 hour, 2 hours), 1 day, 4 days, 2 weeks, and 4 weeks; however, from the viewpoint of an index of the long-term thickening effect, it is preferable to refer to the viscosity 2 weeks or 4 weeks after the cosmetic is prepared. Furthermore, the viscosity after shaking of the cosmetic refers to the viscosity measured after shaking the cosmetic by hand several to several tens of times (e.g., 3 to 20 times) so that the entire cosmetic becomes approximately uniform.

[0078] Conventional water-in-oil emulsion cosmetics containing silicone oil and prepared using an organically modified clay mineral such as bentone can provide a fresh feeling of use when applied to the skin, such that the cosmetic disintegrates immediately. On the other hand, in some embodiments, the water-in-oil emulsion cosmetics of the present disclosure can provide a new feeling of use that has never been experienced before, such as a creamy feeling or a smooth feeling of use, which is different from the use of an organically modified clay mineral such as bentone.

[0079] The water-in-oil emulsion cosmetic of the present disclosure contains the above-mentioned silicone oil, polar oil, and oil-soluble copolymer contained in a base. Here, the blending ratios of the silicone oil, polar oil, and oil-soluble copolymer relative to the total amount of oil in the cosmetic, as well as the mass ratio of the silicone oil to the polar oil, can be the same as those in the base described above.

[0080] On the other hand, the content of silicone oil in the cosmetic can be 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass or more, relative to the total amount of the cosmetic, and can be 40% by mass or less, 35% by mass or less, or 30% by mass or less.

[0081] The content of the polar oil in the cosmetic can be 1.0 mass% or more, 3.0 mass% or more, or 5.0 mass% or more, relative to the total amount of the cosmetic, and can be 20 mass% or less, 15 mass% or less, or 10 mass% or less.

[0082] The content of the oil-soluble copolymer in the cosmetic can be 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, 0.7% by mass or more, or 1.0% by mass or more, and can be 5.0% by mass or less, 4.0% by mass or less, 3.0% by mass or less, or 2.0% by mass or less, relative to the total amount of the cosmetic. The water-in-oil emulsion cosmetic of the present disclosure can also exhibit a thickening effect based on the packing action of multiple water droplets contained in the cosmetic, so it is believed that even with such a relatively low amount of the oil-soluble copolymer as a thickener, the cosmetic of the present disclosure can exhibit excellent thickening properties.

[0083] <Water drop> The water-in-oil emulsion cosmetic of the present disclosure is prepared by adding water to the above-mentioned base, and as a result, such a cosmetic contains water droplets as the aqueous phase or dispersed phase.

[0084] (water) The water that can be used in the water-in-oil emulsion cosmetic of the present disclosure is not particularly limited, but may be water used in cosmetics, quasi-drugs, etc. For example, purified water, ion-exchanged water, tap water, etc. may be used.

[0085] The water content can be 30% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, 50% by mass or more, or 55% by mass or more, and can be 70% by mass or less, 65% by mass or less, or 60% by mass or less, based on the total amount of the cosmetic. When the water content is high, the number of water droplets can be increased, and as a result, the crosslinking points of the network structure as shown in (b) of Figure 2 and the thickening effect based on the packing action of the water droplets can be increased. In other words, an increase in the water content can contribute to an increase in the viscosity of the cosmetic.

[0086] (Surfactant) A surfactant is typically used in the preparation of the water-in-oil emulsion cosmetic of the present disclosure. The surfactant generally exists mainly near the interface between the water phase and the oil phase, i.e., near the periphery of the water droplets, and a part of the surfactant is dispersed in the oil. The surfactant may be incorporated in the base described above, or may be incorporated in the water phase part containing water or the like.

[0087] The surfactant that can be used in the water-in-oil emulsion cosmetic of the present disclosure is not particularly limited, and known surfactants can be used alone or in combination of two or more. For example, silicone surfactants, particularly silicone surfactants modified with a polyether group or a polyglycerin group, can be used.

[0088] Examples of silicone surfactants modified with polyether groups include PEG-11 methyl ether dimethicone, PEG-10 dimethicone, PEG-9 polydimethylsiloxyethyl dimethicone, lauryl PEG-9 polydimethylsiloxyethyl dimethicone, and cetyl PEG / PPG-10 / 1 dimethicone.

[0089] Examples of silicone surfactants modified with a polyglycerin group include polyglyceryl-3 disiloxane dimethicone, polyglyceryl-3 polydimethylsiloxyethyl dimethicone, and lauryl polyglyceryl-3 polydimethylsiloxyethyl dimethicone.

[0090] From the viewpoint of emulsion stability, etc., the amount of surfactant may be 0.1 mass % or more, 0.5 mass % or more, or 1.0 mass % or more, and may be 8.0 mass % or less, 6.0 mass % or less, or 5.0 mass % or less, relative to the total amount of the cosmetic.

[0091] <Optional ingredients> The water-in-oil emulsion cosmetic of the present disclosure can be appropriately blended with various components within a range that does not affect the effects of the present invention. Examples of various components include additive components that can be normally blended into cosmetics. For example, moisturizing agents such as dynamite glycerin, water-soluble polymers, film-forming agents such as silicone-modified polysaccharides, metal ion sequestering agents, lower alcohols, polyhydric alcohols (e.g., 1,3-butylene glycol, PEG1500, dipropylene glycol, etc.), higher fatty acids such as isostearic acid, various extracts, sugars, amino acids, organic amines, polymer emulsions, chelating agents, ultraviolet absorbers, pH adjusters, skin nutrients, vitamins, water-soluble drugs applicable to medicines, quasi-drugs, cosmetics, etc., antioxidants, buffers, preservatives such as phenoxyethanol, antioxidant assistants, slippage improvers, propellants, organic powders, pigments, dyes, colorants, fragrances, acid components, alkali components, etc. can be mentioned. These optional components can be used alone or in combination of two or more, and can be appropriately blended in the oil phase or the water phase. Furthermore, these optional components, particularly oil-soluble components or powder components such as pigments, may be blended in advance in the above-mentioned base.

[0092] The cosmetic preparation of the present disclosure may contain an organically modified clay mineral such as bentone, but from the viewpoint of obtaining the novel feel of use described above, it is preferable that such clay minerals are used in an amount of 1.0 mass % or less, 0.5 mass % or less, less than 0.1 mass %, or 0.05 mass % or less relative to the total amount of the cosmetic preparation, and it is more preferable that no organically modified clay minerals are used.

[0093] <Uses of water-in-oil emulsion cosmetics> The product form of the water-in-oil emulsion cosmetic of the present disclosure is not particularly limited, but examples include skin care cosmetics such as lotion, cream, face oil, body oil, and serum; makeup cosmetics such as foundation, makeup base, lipstick, blusher, eye shadow, mascara, and mascara base; skin cleansers such as makeup removers; hair cleansers; hair cosmetics such as hair treatments and hair oils; sunscreen cosmetics; and hair dyes.

[0094] The water-in-oil emulsion cosmetic of the present disclosure can improve the makeup durability by blending silicone oil, and can express a new feeling of use, such as a creamy feeling of use or a mellow feeling of use, that has never been seen before in a water-in-oil emulsion cosmetic containing silicone oil, by blending a specific oil-soluble copolymer with a polar oil. In addition, the water-in-oil emulsion cosmetic of the present disclosure can reduce or prevent defects such as separation (cracking) when, for example, a pigment is blended. Considering these, it is advantageous to use the water-in-oil emulsion cosmetic of the present disclosure as a foundation that contains a pigment and is desired to have a new feeling of use, among the above product forms.

[0095] <Method for producing water-in-oil emulsion cosmetics> The water-in-oil emulsion cosmetic of the present disclosure can be produced by a conventional method. For example, an oil-soluble copolymer and a surfactant are added to an oil component and stirred to prepare a base, and water is added to the base and stirred to obtain a water-in-oil emulsion cosmetic. If necessary, the above-mentioned optional components may be appropriately mixed with the water or oil component, and a heating means may be applied.

[0096] For example, when producing a water-in-oil emulsion cosmetic containing powder components such as pigments, such as foundation, an oil containing silicone oil and polar oil is heated, and an oil-soluble copolymer and a surfactant are mixed therein to prepare an oil phase part. Next, a powder part containing pigments and the like is mixed with the heated oil phase part to prepare a base, and then a water phase part containing water and the like in a heated state is mixed with the base and slowly cooled to prepare a water-in-oil emulsion cosmetic containing powder components such as pigments.

[0097] Here, the temperature conditions for heating can be, for example, 70° C. or higher, 75° C. or higher, or 80° C. or higher, and can be 95° C. or lower, 90° C. or lower, or 85° C. or lower. The temperature conditions for slow cooling can be, for example, 50° C. or lower, 45° C. or lower, or 40° C. or lower, and can be 25° C. or higher, 30° C. or higher, or 35° C. or higher. EXAMPLES

[0098] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these. In the following, unless otherwise specified, the blending amounts are shown in mass %.

[0099] Examples 1 to 16 and Comparative Examples 1 to 2 Synthesis of Oil-Soluble Copolymer A 1-liter four-neck flask equipped with a reflux condenser, a thermometer, a nitrogen gas inlet tube, and a stirrer was charged with 250 parts by mass of ethanol, 40 parts by mass of glyceryl methacrylate as a hydrophilic monomer, 30 parts by mass of stearyl acrylate as a hydrophobic monomer, and 30 parts by mass of stearyl methacrylate, and the temperature was raised under a nitrogen stream. When the reflux state reached about 80°C, 1 part by mass of 2,2'-azobisisobutyronitrile was added, and the polymerization reaction was allowed to proceed for 4 hours while maintaining the reflux state. Next, the solvent ethanol was distilled off from the solution in the flask to obtain an oil-soluble copolymer.

[0100] The viscosity of water-in-oil emulsion cosmetics obtained by the formulations and production methods shown in Tables 1 and 2 below was evaluated. The results are summarized in Tables 1 and 2.

[0101] Evaluation method 1 (Viscosity evaluation) The viscosity of the cosmetic was evaluated using a B-type viscometer (TVB-type viscometer TVB-10, manufactured by Toki Sangyo Co., Ltd.) under the measurement conditions of an atmosphere of 25°C, rotor No. 2 to 4, and a rotation speed of 12 rpm. The viscosity of the cosmetic after shaking (shaking viscosity) was evaluated using the above viscometer and measurement conditions after shaking the cosmetic by hand about 10 times so that the entire cosmetic became approximately uniform.

[0102] In addition, in the cosmetics of Examples 1 and 2, rotor No. 4 was used, in the cosmetics of Examples 3-4 and Comparative Examples 1-2, rotor No. 2 was used, and in the cosmetics of Examples 5-8, rotor No. 3 was used.

[0103] Examples 1 to 4, Comparative Examples 1 to 2 In Examples 1 to 4 and Comparative Examples 1 and 2, the effects of the presence or absence of an oil-soluble copolymer or a polar oil, and the type of silicone oil were evaluated. The results are shown in Table 1.

[0104] Example 1 An oil containing octyl methoxycinnamate and dimethyl silicone was heated to 80-90°C, and PEG-10 dimethicone, oil-soluble copolymer, and isostearic acid were added to the oil and stirred to prepare a base. While the base was being heated, water was added to the base and stirred, and then the mixture was gradually cooled to 40°C to prepare a water-in-oil emulsion cosmetic.

[0105] The base prepared in Example 1 was cloudy when heated, and a transparent gel-like substance formed at the bottom when left at room temperature. On the other hand, no gel-like substance was formed in the obtained water-in-oil emulsion cosmetic.

[0106] (Examples 2 to 4, Comparative Examples 1 to 2) Cosmetics of Examples 2 to 4 and Comparative Examples 1 and 2 were each prepared in the same manner as in Example 1, except that the blending ratios were changed to those in Table 1.

[0107] The bases prepared in Examples 2 to 4 were all transparent when heated, and when left at room temperature, a transparent gel-like substance formed at the bottom of the bases in Examples 3 and 4. On the other hand, no gel-like substance was formed in any of the obtained water-in-oil emulsion cosmetics.

[0108] [Table 1]

[0109] <result> It was confirmed that all of the bases used in Examples 1 to 4 thickened with the addition of water. In addition, when comparing Example 4 and Comparative Examples 1 and 2, which use the same silicone oil, the cosmetic of Comparative Example 2, which does not contain polar oil, did not show a significant increase in viscosity compared to the cosmetic of Comparative Example 1, which does not contain oil-soluble copolymer, even though it contains an oil-soluble copolymer. On the other hand, the cosmetic of Example 4, which contains polar oil in addition to the oil-soluble copolymer, showed a viscosity increase of more than 10 times compared to the cosmetic of Comparative Example 1.

[0110] Furthermore, as can be seen from Examples 1 to 4, it was confirmed that this effect of increasing viscosity can occur in various silicone oils.

[0111] Examples 5 to 8 The effect of the type of polar oil was evaluated in Examples 5 to 8. The results are shown in Table 2. Table 2 also shows the results of Example 4 and Comparative Examples 1 and 2.

[0112] (Examples 5 to 8) Cosmetics of Examples 5 to 8 were each prepared in the same manner as Example 1, except that the blending ratios were changed to those shown in Table 2.

[0113] Among the bases prepared in Examples 5 to 8, the bases of Examples 5 and 7 were cloudy when heated, while the bases of Examples 6 and 8 were transparent when heated. When these were left at room temperature, a transparent gel-like substance was formed at the bottom in all cases. On the other hand, no gel-like substance was formed in any of the obtained water-in-oil emulsion cosmetics.

[0114] [Table 2]

[0115] <result> It was also confirmed that the bases used in Examples 5 to 8 thickened with the addition of water. In addition, when comparing the cosmetics of Examples 4 to 8, it was confirmed that the cosmetics of Examples 4, 5, and 7, which used octyl methoxycinnamate and diisostearyl malate with an IOB value of 0.28 and tripropylene glycol dipivalate with an IOB value of 0.52 as polar oils, were able to produce a stable thickening effect over a long period of two weeks.

[0116] The cosmetics of Examples 6 and 8, which used cetyl ethylhexanoate with an IOB value of 0.13 and octyl salicylate with an IOB value of 0.60, showed a decrease in viscosity after 2 weeks when not shaken, but it was found that the viscosity was significantly restored when these cosmetics were shaken. This tendency was also confirmed in the cosmetics of Examples 5 and 7. On the other hand, the cosmetic of Comparative Example 2, which contains an oil-soluble copolymer but does not contain a polar oil, also showed a certain degree of viscosity recovery by shaking, but its recovery performance was inferior to that of the cosmetics of Examples 5 to 8. In other words, it was found that the polar oil not only contributes to an increase in viscosity during the preparation of a water-in-oil emulsion cosmetic containing a silicone oil and an oil-soluble copolymer, but also has the function of recovering the viscosity by shaking when the viscosity of the cosmetic decreases over time.

[0117] Examples 9 to 13 The formulations of Examples 9 to 13 are formulations that can be used in foundations and the like that contain pigments, and the effects of the blending ratio of the oil-soluble copolymer in cosmetics with such formulations were evaluated. The results are shown in Table 3.

[0118] Evaluation method 2 (Viscosity evaluation) The viscosity of the cosmetic preparation was evaluated using a B-type viscometer (TVB-type viscometer TVB-10, manufactured by Toki Sangyo Co., Ltd.) under measurement conditions of an atmosphere of 25° C., rotor No. 2 to 4, and a rotation speed of 12 rpm.

[0119] (Evaluation of usability) A panel of five experts applied each cosmetic product to the skin and evaluated the feel on the skin and the lightness of the skin when the product was applied using the following criteria: A: Five people answered that it had a creamy feel when used and that it was light on the fingers. B: 4 people answered that it had a creamy feel when used and that it was light on the fingers. C: 3 subjects answered that it had a creamy feel when used and that it was light on the fingers. D: 2 subjects answered that it had a creamy feel when used and that it was light on the fingers. E: 0 to 1 subjects answered that it had a creamy feel when used and that it was light on the fingers.

[0120] (Evaluation of pigment dispersibility) A panel of five experts applied each cosmetic to the skin and evaluated the pigment dispersion state in the cosmetic based on the following criteria: A: 4 to 5 people answered that the pigments were evenly dispersed without any color floating. B: Two or three people answered that the pigment was evenly dispersed without any color floating. C: 0 to 1 person answered that the pigment was evenly dispersed without any color floating.

[0121] (Evaluation of temporal stability) The appearance of the cosmetic was visually observed 4 weeks after preparation, and the stability over time of the cosmetic was evaluated according to the following criteria: A: No separation (cracks) occurred. B: Slight separation (cracks) was observed. C: Separation (cracks) was evident.

[0122] Example 9 An oil containing octyl methoxycinnamate and dimethyl silicone was heated to 80-90°C, and PEG-10 dimethicone, oil-soluble copolymer, and isostearic acid were added to this oil, followed by stirring to prepare an oil phase part. While this oil phase part was heated, each component of the powder part shown in Table 3 was added and stirred to prepare a base. While the base was heated, water was added to the base and stirred, and then it was gradually cooled to 40°C to prepare a water-in-oil emulsion cosmetic containing a pigment.

[0123] (Examples 10 to 13) Except for changing the blending ratio to that shown in Table 3, the cosmetics of Examples 10 to 13 were each prepared in the same manner as in Example 9.

[0124] [Table 3]

[0125] <result> It was also confirmed that the pigment-containing base used in Examples 9 to 13 thickened with the addition of water. As is clear from Table 3, it was also confirmed that the viscosity of the cosmetic, particularly the viscosity after the day of preparation, increased with an increase in the blended amount of the oil-soluble copolymer. In addition, in consideration of the usability of the cosmetic, it was found that in the case of a water-in-oil emulsion cosmetic containing a pigment, it is advantageous to blend the oil-soluble copolymer in an amount of more than 0.6 mass% relative to the entire cosmetic.

[0126] The viscosities of the cosmetics of Examples 9 to 13 were significantly higher than those of the cosmetics of Examples 1 to 8, which is believed to be due to the influence of the pigment blend.

[0127] Examples 14 to 16 The formulations of Examples 14 to 16 are also formulations that can be used in foundations and the like that contain pigments, and the effects of silicone oil and polar oil in cosmetics with such formulations were evaluated. The results are shown in Table 4. Table 4 also shows the results of Example 11.

[0128] Evaluation method 3 (Viscosity evaluation) The viscosity of the cosmetic preparation was evaluated using a B-type viscometer (TVB-type viscometer TVB-10, manufactured by Toki Sangyo Co., Ltd.) under measurement conditions of an atmosphere of 25° C., rotor No. 2 to 4, and a rotation speed of 12 rpm.

[0129] (Evaluation of temporal stability) The appearance of the cosmetic was visually observed 4 weeks after preparation, and the stability over time of the cosmetic was evaluated according to the following criteria: A: No separation (cracks) occurred. B: Slight separation (cracks) was observed. C: Separation (cracks) was evident.

[0130] (Examples 14 to 16) Except for changing the blending ratio to that shown in Table 4, the cosmetics of Examples 14 to 16 were each prepared in the same manner as in Example 9.

[0131] [Table 4]

[0132] <result> It was also confirmed that the viscosity increased with the addition of water in the pigment-containing bases used in Examples 14 to 16. In addition, as is clear from Table 4, it was confirmed that the viscosity of the cosmetic composition increased as the proportion of polar oil in the oil content increased.

[0133] It was also confirmed that in the case of water-in-oil emulsion cosmetics containing pigments, the ratio of polar oil in the oil content can affect the separation (cracking) of the cosmetics. Therefore, it was found that in the case of such cosmetics, the separation (cracking) of the cosmetics can be reduced or prevented by adjusting the mass ratio of silicone oil to polar oil. [Explanation of symbols]

[0134] 10, 20 Water-in-oil emulsion cosmetic base 11, 21 Oil-soluble copolymers 13, 23 water droplets 15, 25 Water-in-oil emulsion cosmetics

Claims

1. Silicone oil, Polar oils, as well as An oil-soluble copolymer having a monomer unit composed of a hydrophilic monomer and a monomer unit composed of a hydrophobic monomer represented by the following formula 4: Including, The hydrophilic monomer is at least one selected from 2-hydroxyethyl (meth)acrylate, glyceryl (meth)acrylate, PPG-6 (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-2-methylpropyl (meth)acrylate, and the following formula 2: The silicone oil is contained in an amount of 50% by mass or more. Base for water-in-oil emulsion cosmetics: 【Chemistry 1】 In formula 2, R ３ is a hydrogen atom or a methyl group, and R ４ is a linear or branched alkyl or hydroxyalkyl group having 1 to 4 carbon atoms, or a substituent of formula 3 below: 【Chemistry 2】 【Chemistry 3】 In formula 4, R ５ is a linear or branched alkyl group having 16 to 22 carbon atoms, and R ６ is a hydrogen atom or a methyl group.

2. Silicone oil, Polar oils, as well as An oil-soluble copolymer having a monomer unit composed of a hydrophilic monomer and a monomer unit composed of a hydrophobic monomer represented by the following formula 4: Including, The hydrophilic monomer is at least one selected from 2-hydroxyethyl (meth)acrylate, glyceryl (meth)acrylate, PPG-6 (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-2-methylpropyl (meth)acrylate, and the following formula 2: The mass ratio of the silicone oil to the polar oil is 9:1 to 4:

1. Base for water-in-oil emulsion cosmetics: 【Chemistry 4】 In formula 2, R ３ is a hydrogen atom or a methyl group, and R ４ is a linear or branched alkyl or hydroxyalkyl group having 1 to 4 carbon atoms, or a substituent of formula 3 below: 【Chemistry 5】 【Chemistry 6】 In formula 4, R ５ is a linear or branched alkyl group having 16 to 22 carbon atoms, and R ６ is a hydrogen atom or a methyl group.

3. The base material described in claim 1 or 2, wherein the monomer of formula 2 is at least one selected from N-(2-hydroxyethyl)(meth)acrylamide, N-isopropyl(meth)acrylamide, and 2-(meth)acrylamide-2-methylpropanesulfonic acid.

4. The base according to any one of claims 1 to 3, wherein the monomer of formula 4 is at least one selected from cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate.

5. The base material according to any one of claims 1 to 4, wherein the oil-soluble copolymer contains monomer units of the hydrophilic monomer in a range of 30 to 50 mol % and monomer units of the hydrophobic monomer in a range of 50 to 70 mol %.

6. The base according to any one of claims 1 to 5, wherein the silicone oil is at least one selected from the group consisting of dimethyl silicone, methylphenyl polysiloxane, and cyclic polysiloxane.

7. The base material according to any one of claims 1 to 6, wherein the polar oil has an IOB value of 0.10 or more.

8. 8. The base of claim 7, wherein the polar oil is at least one selected from octyl methoxycinnamate, tripropylene glycol dipivalate, cetyl ethylhexanoate, diisostearyl malate, and octyl salicylate.

9. The base according to claim 2, wherein the silicone oil is contained in an amount of 50% by mass or more.

10. 2. The base of claim 1, wherein the mass ratio of the silicone oil to the polar oil is from 9:1 to 4:

1.

11. A base according to any one of claims 1 to 10 which thickens when water is added.

12. A base according to any one of claims 1 to 11, Droplets dispersed in the base and containing water; Including, Water-in-oil emulsion cosmetics.

13. The cosmetic preparation according to claim 12, wherein the content of the oil-soluble copolymer is 0.1% by mass or more.

14. The cosmetic preparation according to claim 12 or 13, wherein the content of the silicone oil is 10% by mass or more.

15. The cosmetic preparation according to any one of claims 12 to 14, further comprising a pigment.

16. The cosmetic preparation according to claim 15, which is used as a foundation.

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