Mannosylerythritol lipid-treated powder, compositions containing the treated powder, and methods for producing the same.

Abstract

Enhance the surface modification effect of powders using MEL (mannosylerythritol lipid). [Solution] The method for producing MEL-treated powder includes a mixing step of obtaining a first mixed liquid containing MEL and an aqueous solvent, a powder addition step of obtaining a second mixed liquid by adding powder to the first mixed liquid, and a drying step of drying the second mixed liquid.

Description

[Technical Field]

[0001] The present invention relates to a method for producing mannnosyl erythritol lipid (hereinafter referred to as "MEL")-treated powder. The present invention also relates to a method for producing a composition containing the MEL-treated powder. The present invention also relates to the MEL-treated powder, and to compositions such as cosmetics containing the MEL-treated powder. [Background Art]

[0002] Powders such as pigments and ultraviolet scattering agents blended in cosmetics are sometimes coated with various compounds on the surface for the purpose of improving the water resistance of the powder to prevent makeup deterioration, or for improving the texture of the powder. As a means for improving the water resistance of powder, for example, a method of coating the surface of powder with a silicone compound or a fluorine compound is known (see Patent Document 1 and Patent Document 2). Further, as a means for improving the texture of powder, for example, a method of coating the surface of powder with collagen is known (see Patent Document 3).

[0003] By the way, in recent years, driven by consumers' growing preference for natural products, cosmetics using compounds derived from natural products have been demanded. For this reason, development of cosmetics that are safe for the human body, have good adhesion to the skin, and have excellent usability using compounds derived from natural products is currently underway. For example, biosurfactants such as glycolipids derived from natural products have high biodegradability, low toxicity and environmentally friendly properties, so their application to the food industry, cosmetics industry, pharmaceutical industry, environmental fields and the like has been studied.

[0004] Mannosylerythritol lipid (MEL) is known as one of the naturally derived glycolipids. MEL is an amphiphilic compound that possesses both hydrophobicity derived from lipid properties and hydrophilicity derived from sugar properties. Because it readily forms a lamellar structure similar to ceramide, a component that forms the human sebum film, it is known to have a skin-improving effect in skincare applications. In this regard, Patent Document 4 reports that MEL also has useful functionality as a surface treatment agent for powders such as pigments. Specifically, the cosmetic pigment described in Patent Document 4 is said to achieve both water resistance and biocompatibility, which could not be obtained with conventional surface treatments using silicone compounds or fluorine compounds, by coating the pigment surface with MEL in a range of 1% to 3% by mass, thereby preventing makeup from smudging and improving adhesion to the skin. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-119741 [Patent Document 2] Japanese Patent Publication No. 2001-002524 [Patent Document 3] Japanese Patent Application Publication No. 61-069710 [Patent Document 4] International Publication No. 2011 / 040357 Pamphlet [Overview of the project] [Problems that the invention aims to solve]

[0006] The surface treatment method for cosmetic pigments using MEL described in Patent Document 4 involves dissolving or dispersing MEL in an organic solvent such as ethanol, stirring and mixing the mixture with the desired pigment, and then removing the organic solvent to obtain a surface-coated cosmetic pigment. However, this method can result in uneven coating of MEL on the pigment surface, preventing the full utilization of MEL's inherent amphiphilic properties. As a result, pigments surface-treated by the method described in Patent Document 4 suffer from insufficient dispersion stability in cosmetics and also have difficulty achieving a smooth feel. Thus, the method in Patent Document 4 results in insufficient surface modification of powders by MEL.

[0007] Therefore, the main objective of the present invention is to further enhance the surface modification effect of powders by MEL. [Means for solving the problem]

[0008] The inventors of the present invention diligently studied means to solve the problems of the prior art described above, and as a result, discovered that by adding powders such as pigments and ultraviolet scattering agents to a mixture containing MEL and an aqueous solvent, further mixing, and then drying this mixture to remove the aqueous solvent, the surface modification effect of the powder by MEL can be improved compared to when only an organic solvent such as ethanol is used as the solvent for MEL. Based on this discovery, the inventors realized that the problems of the prior art could be solved, and thus completed the present invention.

[0009] The first aspect of the present invention relates to a method for producing MEL-treated powder. The method for producing MEL-treated powder includes a mixing step, a powder addition step, and a drying step in that order. In the mixing step, MEL and an aqueous solvent are mixed to obtain a first mixed solution containing MEL and an aqueous solvent. As the aqueous solvent, for example, pure water (such as deionized water), purified water, buffer solution (such as phosphate buffer solution), physiological saline solution, or a mixture of one or more of these can be used. In the powder addition step, a second mixed solution is obtained by adding powder to the first mixed solution. The powder is the material to be surface-treated with MEL, and examples include inorganic pigments such as titanium dioxide, zinc oxide, and iron oxide, and powders used as ultraviolet scattering agents. In the drying step, the aqueous solvent is removed by drying the second mixed solution. This yields a powder whose surface has been modified by MEL.

[0010] Generally, MEL is considered to be poorly soluble or dispersible in aqueous solvents such as pure water, and conventionally, organic solvents such as ethanol have been commonly used as solvents for MEL. On the other hand, the inventors of this invention have unexpectedly discovered that using an aqueous solvent as a solvent for MEL improves the dispersion stability of the resulting MEL-treated powder in cosmetics and provides a smoother feel, thus improving the functionality of MEL. It is presumed that this effect is due to the effective expression of the amphiphilic properties of MEL by using an aqueous solvent, resulting in a uniform coating of MEL on the powder surface.

[0011] In the method for producing MEL-treated powder according to the present invention, it is preferable that the first mixed liquid further contains alcohol in the mixing step. By including alcohol in the first mixed liquid in this way, the surface modification effect of the powder by MEL is further improved. This is thought to be because alcohol has a high affinity for aqueous solvents and also possesses the properties of an organic solvent, thus playing a bridging role between the aqueous solvent and MEL. As a result, the coating of MEL on the surface of the obtained MEL-treated powder becomes more uniform, and the functionality such as dispersion stability and usability is further improved.

[0012] In the method for producing MEL-treated powder according to the present invention, it is preferable that the mass ratio of the aqueous solvent to the alcohol (aqueous solvent / alcohol) in the first mixed solution containing the aqueous solvent and the alcohol is 1 or more. Thus, in the present invention, the aqueous solvent is contained in the first mixed solution in an amount equal to or greater than that of the alcohol. By containing the aqueous solvent and alcohol in such a ratio, the amphiphilic properties of MEL can be effectively brought out. That is, it is thought that the relatively high content of the aqueous solvent increases the orientation of the hydrophilic and hydrophobic parts of the MEL molecule, and adsorption to the powder surface occurs more regularly. As a result, the obtained MEL-treated powder exhibits superior dispersion stability and a smooth feel compared to the case where the content of the aqueous solvent is low. Furthermore, this ratio also has the advantage of reducing the environmental burden in the manufacturing process.

[0013] In the method for producing MEL-treated powder according to the present invention, it is preferable that the temperature of the first mixed liquid when adding the powder in the powder addition step is 60°C or higher and below the boiling point of the alcohol. If the alcohol is a mixture of multiple types, the boiling point of the alcohol referred to here means the lowest boiling point among the alcohols used. By adding the powder while maintaining the first mixed liquid within this temperature range, the adsorption efficiency of MEL to the powder surface is improved. Specifically, under temperature conditions of 60°C or higher, the mobility of MEL molecules increases, promoting interaction with the powder surface. Furthermore, within this temperature range, the association state of MEL is optimized, achieving uniform coating on the powder surface. On the other hand, by keeping the temperature below the boiling point of the alcohol (for example, about 78°C for ethanol), rapid evaporation of the alcohol can be suppressed. Also, since aqueous solvents (for example, water at about 100°C) generally have higher boiling points than alcohol, their evaporation is also suppressed, thus maintaining a stable dispersion state of MEL. As a result, the obtained MEL-treated powder has a more uniform surface state and exhibits excellent dispersion stability.

[0014] In the method for producing MEL-treated powder according to the present invention, the powder to be surface-treated is preferably one or more selected from titanium dioxide, zinc oxide, and iron oxide. These powders are widely used in cosmetics as ultraviolet scattering agents and pigments. Therefore, by surface-treating these powders with MEL, it is possible to achieve both excellent usability and functionality in compositions such as cosmetics.

[0015] The method for producing MEL-treated powder according to the present invention preferably further includes a filtration step after the powder addition step and before the drying step. In the filtration step, the second mixed liquid obtained in the powder addition step is filtered to separate it into a filtrate and a filtrate. The filtration referred to here includes not only the process of separating the filtrate and filtrate using a filter material such as a filter, but also the process of allowing the second mixed liquid to stand to settle the filtrate and removing the supernatant filtrate. The filtrate is the liquid side separated in the filtration step and mainly contains a solvent (such as an aqueous solvent) and MEL that was not adsorbed on the powder surface. On the other hand, the filtrate is the solid (particle) side separated in the filtration step and mainly contains powder with the solvent and MEL adsorbed on its surface. In the subsequent drying step, the filtrate is dried. That is, the filtrate is removed, and only the filtrate is subjected to the drying treatment. By performing the filtration step before the drying step in this way, MEL that was not adsorbed on the powder surface can be removed, and a MEL-treated powder with a more uniform surface condition can be obtained. In addition, the drying efficiency in the drying step is improved, and there is also the advantage of reducing the environmental burden in the manufacturing process.

[0016] The method for producing MEL-treated powder according to the present invention preferably further includes a stirring step after the mixing step and before the powder addition step. The stirring step is a step of stirring a first mixed liquid that has been heated to 60°C or higher and below the boiling point of the aqueous solvent. When the aqueous solvent is a mixture of water and other solutes, the boiling point of the aqueous solvent referred to here means the boiling point of water (100°C). Furthermore, if the first mixed liquid contains alcohol, the temperature at which the aqueous solvent is heated should be below the boiling point of the alcohol. By including this stirring step, the dispersion state of MEL in the aqueous solvent becomes more uniform. In particular, stirring under temperature conditions of 60°C or higher increases the mobility of MEL molecules and improves dispersibility in the aqueous solvent. In addition, by keeping the temperature below the boiling point of the aqueous solvent, rapid evaporation of the solvent can be prevented and a stable dispersion state can be maintained.

[0017] A second aspect of the present invention relates to a method for producing a composition containing MEL-treated powder. The method for producing a composition containing MEL-treated powder according to the present invention includes the steps of obtaining MEL-treated powder by the production method described in the first aspect above, and producing a composition containing this MEL-treated powder.

[0018] A third aspect of the present invention relates to MEL-treated powder. The MEL-treated powder according to the present invention is characterized by being obtained by the manufacturing method described in the first aspect above. In the MEL-treated powder of the present invention, the state of MEL coating on the powder surface is a state unique to the manufacturing method using an aqueous solvent, but it is difficult to directly specify its characteristics by specific numerical values ​​or structures. For this reason, it is impossible or impractical to directly identify the MEL-treated powder of the present invention by its structure or characteristics.

[0019] A fourth aspect of the present invention relates to a composition containing the MEL-treated powder described in the third aspect above. [Effects of the Invention]

[0020] According to the present invention, the surface modification effect of powders by MEL can be further enhanced. [Brief explanation of the drawing]

[0021] [Figure 1] Fig. 1 is a sequence diagram showing an embodiment of the method for producing MEL-treated powder according to the present invention. MODE FOR CARRYING OUT THE INVENTION

[0022] Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the modes described below, and also includes appropriate modifications made by those skilled in the art within the range obvious from the following modes. In the present specification, unless otherwise specified, the expression "A to B" means "not less than A and not more than B".

[0023] The present invention relates to a MEL-treated powder and a method for producing the same. This embodiment particularly relates to a MEL-treated powder to be incorporated into cosmetics and a method for producing the same. The MEL-treated powder is a powder whose surface is coated with MEL (mannosyl erythritol lipid). By modifying the surface of the powder to be incorporated into compositions such as cosmetics with MEL, excellent dispersion stability and a smooth feeling when used are achieved. In the MEL-treated powder of the present invention, by using an aqueous solvent in the production process, the amphipathic property of MEL molecules is effectively expressed, and uniform coating on the powder surface is realized.

[0024] MEL is a known substance as described in Patent Document 4. As described in Patent Document 4, MEL is a glycolipid composed of mannose, erythritol (a sugar alcohol) and a fatty acid, and is represented by the following general formula. Chemical formula (wherein R1 and R2 each represent an aliphatic acyl group having 6 to 20 carbon atoms, which may be the same or different; R3 and R4 each represent hydrogen or an acetyl group, which may be the same or different; and n represents an integer of 2 to 4.)

[0025] MEL is a glycolipid primarily produced by basidiomycete yeasts of the genus Moesziomyces (formerly Pseudozyma). Representative producing strains include Moesziomyces antarcticus (formerly Pseudozyma antarctica) and Moesziomyces aphidis (formerly Pseudozyma aphidis, Pseudozyma tsukubaensis, Pseudozyma hubeiensis). These strains utilize hydrophobic substrates such as vegetable oils and hydrocarbons as their primary carbon source to secrete MEL extracellularly. The isomers of MEL produced (MEL-A, MEL-B, etc.) can be controlled by optimizing the strain and culture conditions (type and concentration of carbon source, type and concentration of nitrogen source, culture temperature, pH, dissolved oxygen concentration, etc.).

[0026] Various isomers of MEL are known depending on the presence or absence of acetyl groups attached to R3 and R4 of the mannose residue shown in the general formula above, the type of sugar alcohol glycosidically bonded to mannose, and the isomer of that sugar alcohol. Representative isomers of MEL are MEL-A, MEL-B, MEL-C, and MEL-D, shown in the following general formulas, and have a 4-O-β-D-mannopyranosyl-(2S,3R)-erythritol structure. It is also known that inverted optical isomers of MEL exist, such as inverted MEL-B and inverted MEL-D shown in the following general formulas, which have a 4-O-β-D-mannopyranosyl-meso(2R,3S)-erythritol structure. In the following general formulas, n represents an integer from 4 to 18. [ka] [ka] [ka] [ka] [ka] [ka]

[0027] In this invention, one or more of MEL-A, MEL-B, inverted MEL-B, MEL-C, MEL-D, and inverted MEL-D can be used in combination. MEL-A has a structure in which one acetyl group (-AcO) is bonded to the carbon at position 4 and one to the carbon at position 6 of mannose. MEL-B and inverted MEL-B have a structure in which one acetyl group is bonded to the carbon at position 6 of mannose and one hydroxyl group (-OH) is bonded to the carbon at position 4. MEL-C has a structure in which one hydroxyl group is bonded to the carbon at position 4 of mannose and one acetyl group is bonded to the carbon at position 6. MEL-D and inverted MEL-D have no acetyl groups bonded, and one hydroxyl group is bonded to the carbon at position 4 and one to the carbon at position 6. Thus, the hydrophobic / hydrophilic balance differs depending on the number of acetyl groups and hydroxyl groups, so the optimal MEL should be selected according to the application.

[0028] MEL-treated powders can be incorporated into a variety of compositions. Examples of compositions containing MEL-treated powders include cosmetics, quasi-drugs, pharmaceuticals, and daily necessities. Examples of cosmetics include foundations, face powders, lipsticks, eyeshadows, blushes, primers, lotions, creams, sunscreens, and antiperspirants.

[0029] MEL-treated powders can be used in a variety of applications in cosmetics. For example, MEL-treated titanium dioxide or zinc oxide powders are suitably used as UV scattering agents in sunscreen cosmetics. In this case, MEL treatment improves the dispersion stability of the powder, which suppresses uneven application to the skin and prevents makeup from smudging. Furthermore, MEL-treated inorganic powders such as talc, mica, or sericite are suitably used as base powders for makeup cosmetics such as foundation, face powder, or eyeshadow. In this case, MEL treatment improves the slipperiness of the powder and enhances its adhesion to the skin, resulting in a better feel when applied. In addition, MEL-treated coloring pigments such as iron oxide and carbon black are suitably used as pigments for colored cosmetics such as lipstick, eyeliner, or mascara. In this case, MEL treatment improves the dispersion stability of the pigment, which enables uniform color development without unevenness and provides a long-lasting, good-wearing finish.

[0030] These cosmetic compositions may contain MEL-treated powder in an amount of 0.1% to 50% by mass. More specifically, the lower limit of the amount of MEL-treated powder in the composition is preferably 0.5%, 1%, 5%, 8%, 10%, 12%, or 15% by mass. The upper limit of the amount of MEL-treated powder in the composition is preferably 30%, 25%, or 20% by mass. The amount of MEL-treated powder can be adjusted as appropriate depending on the intended use of the powder. Specifically, when using MEL-treated powder as an ultraviolet scattering agent, it is preferable to include 3 to 30% by mass; when using it as a base powder, 10 to 50% by mass; and when using it as a coloring pigment, 0.1% to 20% by mass or less.

[0031] Furthermore, the composition containing the MEL-treated powder of the present invention may optionally contain various additives such as oily components, surfactants, humectants, preservatives, chelating agents, pH adjusters, viscosity adjusters, antioxidants, UV absorbers, anti-inflammatory agents, whitening agents, and fragrances. These additives may be blended in the types and amounts commonly used in the relevant field.

[0032] Next, with reference to the sequence diagram in Figure 1, an embodiment of the method for producing MEL-treated powder according to the present invention will be described. As shown in Figure 1, the production method according to this embodiment mainly includes six steps: a mixing step (S1), a first stirring step (S2), a powder addition step (S3), a second stirring step (S4), a filtration step (S5), and a drying step (S6). By going through each of these steps, MEL-treated powder in which MEL is uniformly coated on the powder surface can be efficiently produced. The following describes each step in detail.

[0033] In the mixing step (S1), MEL and an aqueous solvent are mixed to prepare the first mixture. Specifically, the lower limit of the amount of MEL added to the aqueous solvent (MEL / aqueous solvent) is preferably 0.1% by mass, 0.15% by mass, 0.2% by mass, or 0.25% by mass. The upper limit of the amount of MEL added to the aqueous solvent is preferably 3% by mass, 2.5% by mass, 2% by mass, 1.5% by mass, or 1% by mass. As the aqueous solvent, pure water, purified water, buffer solution, or physiological saline solution can be used, but pure water is particularly preferred. The first mixture may be obtained by dissolving or dispersing MEL only in the aqueous solvent. However, as will be explained below, alcohol may also be mixed in addition to MEL and the aqueous solvent in the first mixture.

[0034] In this embodiment, alcohol is further mixed into the first mixture. As the alcohol, methanol, ethanol, propanol, isopropyl alcohol, or lower alcohols such as butanol can be used. Among these, ethanol is preferred as the alcohol added to the first mixture. When alcohol is further mixed into the first mixture, the lower and upper limits of the amount of MEL added to the mixed solvent of the aqueous solvent and the alcohol (MEL / mixed solvent) may be the same as the lower and upper limits of the amount of MEL added to the aqueous solvent (MEL / aqueous solvent) described above.

[0035] Furthermore, when using a mixed solvent of an aqueous solvent and an alcohol, the mass ratio of the aqueous solvent to the alcohol (aqueous solvent / alcohol) is preferably 1 or more, and preferably 1.5 or more or 2.0 or more. The upper limit of the mass ratio of the aqueous solvent to the alcohol may be 9.0 or less, 5.0 or less, or 3.0 or less. In particular, setting the mass ratio of the aqueous solvent to the alcohol to 2.0 to 9.0 improves the dispersibility of MEL. In one embodiment, a first mixed solution in a stable dispersion state can be obtained by adding 1.00% by mass of MEL to a mixed solvent of purified water and ethanol and stirring.

[0036] When using a mixed solvent of an aqueous solvent and an alcohol, the aqueous solvent and MEL may be mixed and thoroughly dissolved or dispersed before adding the alcohol. In this case, the MEL can be thoroughly dispersed in the aqueous solvent, and the subsequent addition of alcohol can further stabilize the dispersion of the MEL. On the other hand, the method of mixing the alcohol and MEL and then adding the aqueous solvent after dissolving is undesirable. This is because when the aqueous solvent is added to the state where MEL is dissolved in alcohol, the MEL tends to precipitate rapidly, making aggregation more likely.

[0037] Next, in the first stirring step (S2), the first mixed solution obtained in the mixing step is heated or stirred while being heated. Specifically, in the first stirring step, it is preferable to heat the first mixed solution to 20°C or higher or 25°C or higher, and it is particularly preferable to heat it to 55°C or higher or 60°C or higher. The upper limit of the temperature to which the first mixed solution is heated is below the boiling point of the solvent (aqueous solvent only, or a mixed solvent of aqueous solvent and alcohol). For example, the boiling point of pure water at atmospheric pressure is about 100°C, and the boiling point of ethanol is about 78°C. Therefore, if the first mixed solution is a mixture of pure water, ethanol, and MEL, it is preferable that the upper limit of the temperature range to which this first mixed solution is heated is 75°C or 70°C. By stirring under such temperature conditions, the mobility of the MEL molecules is increased, the dispersibility in the aqueous solvent is improved, and the adsorption efficiency of MEL to the powder surface in the subsequent powder addition step is also increased.

[0038] The stirring time in the first stirring step is preferably in the range of 5 to 60 minutes, and more preferably in the range of 10 to 30 minutes. A dispersion device such as a propeller-type stirrer, homomixer, or ultrasonic disperser can be used for stirring. For example, the first mixture can be stirred using a homomixer at a rotational speed of 1000 to 10000 rpm. It is preferable to keep the temperature of the first mixture constant during the first stirring step. This is to prevent the dispersion state of MEL from becoming unstable due to temperature changes.

[0039] In the first stirring step, it is preferable to perform the work in a clean environment to prevent foreign matter such as dust from being mixed into the first mixture. Furthermore, it is preferable to use a sealable container to prevent evaporation of the first mixture. However, since the internal pressure may rise in a completely sealed state, it is desirable to provide a pressure reducing valve or the like as needed.

[0040] Next, in the powder addition step (S3), the powder to be surface-treated is added to the first mixture obtained in the first stirring step to obtain a second mixture. In this step, it is important to add the powder while maintaining the temperature of the first mixture, which was heated during stirring. By raising the temperature range of the first mixture in this way, the mobility of the MEL molecules is kept high, and adsorption to the powder surface proceeds efficiently. Furthermore, it is preferable to add the powder to the first mixture while stirring is continuing. This is because if the powder is added with stirring stopped, the powder tends to aggregate locally, resulting in an uneven dispersion state, which may lead to variations in the MEL coating state. In other words, by adding the powder while continuing stirring, the powder is uniformly dispersed in the first mixture, and surface treatment with MEL can be performed efficiently.

[0041] In this embodiment, the powder used in the powder addition step is an ultraviolet scattering agent or a pigment. An ultraviolet scattering agent refers to a particulate substance that can absorb, reflect, or scatter ultraviolet rays to protect the skin from ultraviolet radiation. A pigment refers to a coloring agent that is insoluble in a dispersion medium such as water or oil, and exhibits a coloring effect when dispersed in the dispersion medium. The particulate substances that make up the ultraviolet scattering agent or pigment are generally inorganic substances.

[0042] The powder used in the powder addition process is preferably an ultraviolet scattering agent. Examples of ultraviolet scattering agents include titanium dioxide, zinc oxide, cerium oxide, and iron oxide. Alternatively, these materials may be used in fine or compound form as ultraviolet scattering agents. Considering the high ultraviolet scattering effect, it is particularly preferable to use one or two of titanium dioxide and zinc oxide as the ultraviolet scattering agent. Titanium dioxide and zinc oxide are known as white pigments with excellent ultraviolet scattering effects and are widely used as ultraviolet scattering agents in cosmetic applications. Iron oxide, on the other hand, is widely used as a coloring agent in cosmetic applications as a coloring pigment that exhibits various shades by adjusting its composition and particle size.

[0043] Titanium dioxide and zinc oxide, widely used as UV scattering agents, preferably have an average particle diameter of 300 nm or less, 250 nm or less, 100 nm or less, 80 nm or less, or 10 nm or less. While there is no particular lower limit to the average particle diameter, it should be 5 nm or greater, and more preferably 10 nm or greater. In particular, in the particle diameter range of 100 nm or less, effective scattering of UV wavelengths is achieved while suppressing the scattering of visible light, thus preventing white cast during application. Furthermore, in the particle diameter range of 101 nm to 300 nm, excellent coloring and concealing power can be obtained, while also ensuring dispersion stability in cosmetics. On the other hand, iron oxide, widely used as a coloring pigment, preferably has an average particle diameter in the range of 5 to 1000 nm, and more preferably in the range of 5 to 300 nm. Excellent coloring and concealing power can be obtained in this particle diameter range. In this specification, "average particle diameter" refers to the average particle size value of 50% of the cumulative volume measured using a laser diffraction / scattering particle size distribution analyzer. By using a UV scattering agent with a relatively small particle size, with an average particle diameter of 101 to 300 nm, the dispersibility of the powder (UV scattering agent) in the second mixed solution is improved. It is preferable to pre-classify these powders to adjust their particle size distribution. This is because a wide particle size distribution can easily lead to variations in the MEL coating state.

[0044] When the mixture of MEL and powder is considered to be 100% by mass, the lower limit of the amount of powder added is preferably 90% or 95% by mass, and preferably 98% or 99% by mass. The upper limit of the amount of powder added is not particularly limited, but it may be 99.9% or 99.5% by mass. In other words, the MEL content relative to the powder can be trace. By adding the powder in this ratio, the amount of MEL coating on the powder surface can be optimized. It is preferable to add the powder to the first mixture in small amounts in several stages, rather than adding the entire amount at once. This improves the dispersibility of the powder and makes the MEL coating more uniform.

[0045] The second stirring step (S4) involves stirring the second mixture obtained in the powder addition step. The second stirring step continues stirring the second mixture after powder addition for a further 10 to 60 minutes, preferably 20 to 40 minutes. In the second stirring step, a dispersion device such as a propeller-type stirrer, homomixer, or ultrasonic disperser can be used, similar to the first stirring step. However, the stirring speed in the second stirring step is preferably set to a level that does not crush the powder. For example, when using a propeller-type stirrer, it should be around 100 to 4000 rpm. It is also preferable to keep the temperature of the second mixture constant during this second stirring step.

[0046] In the filtration step (S5), the second mixture, which has undergone the second stirring step, is filtered to separate the filtrate from the filtrate. The purpose of this filtration step is to separate the powder on which MEL is adsorbed (filtrate) from the solvent containing MEL that was not adsorbed on the powder surface (filtrate). The filtrate is subjected to the next drying step, and the filtrate is removed.

[0047] As a filtration method in the filtration process, for example, a static sedimentation method can be employed, in which the second mixture is allowed to stand to allow the powder (filtrate) to settle naturally, and the supernatant liquid (filtrate) is removed. In the static sedimentation method, the second mixture is transferred to a suitable container, and the powder is allowed to settle naturally by gravity. This method has the advantage of not requiring special filtration equipment and placing little physical stress on the powder. In particular, this method is effective in obtaining a uniform surface modification effect without damaging the structure of MEL adsorbed on the powder surface. The temperature of the second mixture is affected by the settling rate and the viscosity of the solvent, so it is preferable to maintain it in the range of 25 to 60°C. In particular, by maintaining the second mixture at 40 to 50°C, it is possible to ensure an appropriate settling rate while stabilizing the adsorption state of MEL. The settling time can be appropriately adjusted depending on the type of powder used, the particle size, and the density. For example, in the case of titanium dioxide or zinc oxide with an average particle size of 100 nm or less, it is sufficient to let it stand for 12 to 24 hours. On the other hand, for iron oxide and other materials with an average particle size of 300 nm or more, standing for 6 to 12 hours is sufficient. Methods for removing the supernatant (filtrate) include decantation, siphon, or pipette aspiration. In particular, to avoid disturbing the powder layer, it is preferable to carefully remove the supernatant using a siphon or pipette without tilting the container. Furthermore, removing the supernatant gradually from the top of the sedimentation layer, rather than removing the entire amount at once, can prevent the sedimentation layer from rising.

[0048] In addition, known methods such as suction filtration, pressure filtration, or centrifugal separation can be used in the filtration process. For example, it is preferable to perform filtration under reduced pressure using a suction filtration device. It is important to select the filter used for filtration considering the particle size of the powder. Specifically, it is preferable to use a filter with a pore size (mesh opening) in the range of 0.01 to 10 μm, and more preferably a filter in the range of 0.1 to 5 μm. As for the filter material, polytetrafluoroethylene (PTFE), polyethersulfone (PES), cellulose mixed ester (MCE), nylon, or glass fiber can be used.

[0049] Furthermore, the filtrate obtained in the filtration process can also be washed. Specifically, excess MEL physically adhering to the powder surface can be removed by washing the filtrate 1 to 3 times with a small amount of purified water or alcohol. However, if a washing process is performed, it should be carried out under mild conditions that do not cause MEL desorption. For example, the temperature of the washing solvent should be room temperature (20-25°C), and the number of washes should be kept to the minimum necessary.

[0050] In the drying step (S6), the solvent (aqueous solvent, alcohol) is removed by drying the filtrate (powder with MEL adsorbed on its surface) obtained in the filtration step. By almost completely removing the solvent in this drying step, the final MEL-treated powder is obtained. In this embodiment, the drying step includes low-temperature drying, high-temperature drying, grinding, and heat treatment in this order.

[0051] The drying process is preferably carried out in multiple temperature stages. Specifically, it is preferable to employ a multi-stage drying method in which low-temperature drying is performed first, followed by high-temperature drying. In the first stage of low-temperature drying, it is preferable to dry the filtrate at a temperature range of, for example, 40 to 80°C for 1 to 4 hours, and particularly preferably at 50 to 70°C for about 1.5 to 3 hours. The purpose of this low-temperature drying is to gently remove the solvent without damaging the structure or orientation of the MEL adsorbed on the powder surface. In particular, in this first stage of low-temperature drying, alcohols with a lower boiling point than aqueous solvents are mainly removed. Subsequently, in the second stage of high-temperature drying, it is preferable to dry at a higher temperature than the low-temperature drying, for example at a temperature range of 65 to 100°C for 6 to 24 hours, and particularly preferably at 75 to 95°C for 10 to 14 hours. This second stage of high-temperature drying further removes any remaining solvent inside the powder and stabilizes the adsorption state of MEL on the powder surface. In particular, this second stage of high-temperature drying primarily removes aqueous solvents that have a higher boiling point than alcohol.

[0052] Furthermore, it is preferable to perform a grinding treatment on the dried material obtained by the above drying treatment. By performing the grinding treatment, aggregates of particles generated during the drying process are broken down, and a MEL-treated powder with a uniform particle size distribution can be obtained. For the grinding treatment, known grinding devices such as ball mills, jet mills, or vibratory mills can be used. In particular, in order to avoid excessive physical impact on the powder, grinding under relatively gentle conditions is preferable. For example, short-time (about 10 to 30 minutes) ball milling using a small amount of stainless steel balls or manual grinding using a mortar and pestle are suitable.

[0053] Furthermore, it is preferable to perform a final heat treatment on the dried pulverized material after the pulverization process. Specifically, in the heat treatment, it is preferable to heat the dried pulverized material at a temperature range of 100 to 130°C for 3 to 10 hours, and particularly preferable to heat it at 105 to 120°C for 4 to 8 hours. This final heat treatment thermally stabilizes the structure of MEL adsorbed on the powder surface, making it possible to obtain a MEL-treated powder that is stable over a long period of time. In addition, this heat treatment completely removes any remaining solvent, resulting in a highly safe powder.

[0054] The above-described drying process can utilize a constant-temperature dryer, a vacuum dryer, or a reduced-pressure dryer. In particular, it is preferable to use a forced-circulation type constant-temperature dryer to obtain a uniform temperature distribution. Furthermore, using a vacuum dryer or reduced-pressure dryer is effective in shortening the drying time. However, since rapid evaporation of the solvent under vacuum conditions may alter the MEL state on the powder surface, appropriate temperature and vacuum control are necessary.

[0055] As described above, the method for producing MEL-treated powder according to this embodiment includes, in order: a mixing step (S1) to obtain a first mixed solution containing MEL and an aqueous solvent; a stirring step (S2) to stir the first mixed solution; a powder addition step (S3) to obtain a second mixed solution by adding powder to the stirred first mixed solution; a stirring step (S4) to stir the second mixed solution; a filtration step (S5) to filter the second mixed solution obtained in the stirring step to separate it into a filtrate and a filtrate; and a drying step (S6) to dry the filtrate. In particular, in this embodiment, an aqueous solvent is deliberately used as the solvent for MEL, and alcohol is added as needed to effectively bring out the amphiphilic properties of MEL and achieve uniform coating on the powder surface. Furthermore, this embodiment includes measures to enhance the powder surface modification effect by MEL, such as temperature conditions in each step (especially above 60°C and below the boiling point of the solvent), an appropriate ratio of aqueous solvent to alcohol (aqueous solvent / alcohol ≥ 1), and the adoption of a multi-stage drying method.

[0056] The MEL-treated powder obtained by this manufacturing method exhibits a more uniform MEL coating on the powder surface compared to powders produced using only conventional organic solvents such as ethanol. As a result, the resulting MEL-treated powder exhibits improved dispersion stability in compositions such as cosmetics, resulting in a smooth feel and fully demonstrating the inherent functionality of MEL. Furthermore, the manufacturing method of this embodiment has the advantage of reducing environmental impact by primarily using an aqueous solvent. Thus, the manufacturing method according to this embodiment can produce MEL-treated powder with excellent functionality for cosmetic applications in an efficient and environmentally friendly manner. [Examples]

[0057] Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[0058] [1. Manufacturing conditions for MEL-treated powder] In this example, the effects of the ratio of aqueous solvent to alcohol, stirring temperature, and the presence or absence of filtration on product characteristics were mainly investigated in the method for producing MEL-treated powder. In Examples 1 to 14, basically, 1 part by mass (0.25% by mass) of (A) MEL-B was added to 400 parts by mass of solvent, which was a mixture of (B) purified water and (D) ethanol as needed, and stirred. After the MEL dispersed in the solvent and the solvent reached the target temperature, stirring was continued for another 10 minutes. While maintaining the stirring state, 99 parts by mass (24.75% by mass) of (C1) titanium dioxide was added to 400 parts by mass of solvent. In other words, the concentration of MEL and titanium dioxide was set to 100 parts by mass per 400 parts by mass of solvent. After adding titanium dioxide (250 nm), stirring was performed for 30 minutes, filtration was performed as needed, and then the treated powder was dried. For filtration, suction filtration was performed using quantitative filter paper No. 5C with a Nutsche filter. Furthermore, the drying conditions involved drying at 60°C for 2 hours, followed by drying at 85°C for 12 hours, followed by pulverization and then heat treatment at 110°C for 6 hours. This resulted in a surface-coated powder in which 99% by mass of titanium oxide (powder) was treated with 1% by mass of MEL. Details of each example and comparative example are shown in Tables 1 to 3.

[0059] [Table 1]

[0060] [Table 2]

[0061] [Table 3]

[0062] As shown in the table above, in Example 1, only purified water was used as the dispersion solvent. In addition, during the stirring process after adding MEL to the solvent, the solvent temperature was set to 60°C, and filtration was performed after the addition and stirring of titanium dioxide.

[0063] In Example 2, a mixed solvent of purified water and ethanol was used as the dispersion solvent, and the MEL-treated powder was obtained in the same manner as in Example 1, except that the mixing ratio of purified water to ethanol was 9:1.

[0064] In Example 3, a mixed solvent of purified water and ethanol was used as the dispersion solvent, and the mixing ratio of purified water to ethanol was set to 8:2. Otherwise, the MEL-treated powder was obtained in the same manner as in Example 1.

[0065] In Example 4, a mixed solvent of purified water and ethanol was used as the dispersion solvent, and the MEL-treated powder was obtained in the same manner as in Example 1, except that the mixing ratio of purified water to ethanol was 7:3.

[0066] In Example 5, a mixed solvent of purified water and ethanol was used as the dispersion solvent, and the mixing ratio of purified water to ethanol was set to 6:4. Otherwise, the MEL-treated powder was obtained in the same manner as in Example 1.

[0067] In Example 6, a mixed solvent of purified water and ethanol was used as the dispersion solvent, and the mixing ratio of purified water to ethanol was set to 5:5. Otherwise, the MEL-treated powder was obtained in the same manner as in Example 1.

[0068] In Example 7, MEL-treated powder was obtained in the same manner as in Example 1, except that the temperature of the solvent during the stirring process after adding MEL to the solvent was set to 25°C.

[0069] In Example 8, a mixed solvent of purified water and ethanol was used as the dispersion solvent, with a mixing ratio of purified water to ethanol of 9:1, and the solvent temperature during the stirring process was set to 25°C. Aside from these differences, the MEL-treated powder was obtained in the same manner as in Example 1.

[0070] In Example 9, a mixed solvent of purified water and ethanol was used as the dispersion solvent, with a mixing ratio of purified water to ethanol of 8:2, and the solvent temperature during the stirring process was set to 25°C. Aside from these differences, the MEL-treated powder was obtained in the same manner as in Example 1.

[0071] In Example 10, a mixed solvent of purified water and ethanol was used as the dispersion solvent, with a mixing ratio of purified water to ethanol of 7:3, and the solvent temperature during the stirring process was set to 25°C. Aside from these differences, the MEL-treated powder was obtained in the same manner as in Example 1.

[0072] In Example 11, a mixed solvent of purified water and ethanol was used as the dispersion solvent, with a mixing ratio of purified water to ethanol of 6:4, and the solvent temperature during the stirring process was set to 25°C. Aside from these differences, the MEL-treated powder was obtained in the same manner as in Example 1.

[0073] In Example 12, a mixed solvent of purified water and ethanol was used as the dispersion solvent, with a mixing ratio of purified water to ethanol of 5:5, and the solvent temperature during the stirring process was set to 25°C. Aside from these differences, the MEL-treated powder was obtained in the same manner as in Example 1.

[0074] In Example 13, a mixed solvent of purified water and ethanol was used as the dispersion solvent, with a mixing ratio of purified water to ethanol of 7:3. Except for omitting the filtration process after the addition and stirring of titanium dioxide, the MEL-treated powder was obtained in the same manner as in Example 1.

[0075] In Example 14, a mixed solvent of purified water and ethanol was used as the dispersion solvent, with a mixing ratio of purified water to ethanol of 5:5. Except for omitting the filtration process after the addition and stirring of titanium dioxide, the MEL-treated powder was obtained in the same manner as in Example 1.

[0076] In Comparative Example 1, a MEL-treated powder was obtained in the same manner as in Example 1, except that only ethanol was used as the dispersion solvent.

[0077] In Comparative Example 2, MEL-treated powder was obtained in the same manner as in Example 1, except that only ethanol was used as the dispersion solvent and the solvent temperature during the stirring process was set to 25°C.

[0078] In Comparative Example 3, MEL-treated powder was obtained in the same manner as in Example 1, except that only ethanol was used as the dispersion solvent and the filtration treatment after the addition and stirring of titanium dioxide was omitted.

[0079] In Comparative Example 4, MEL-treated powder was obtained in the same manner as in Example 1, except that only isopropyl alcohol was used as the dispersion solvent and the filtration treatment after the addition and stirring of titanium dioxide was omitted.

[0080] As described above, in this example and comparative example, in order to find the optimal conditions for the manufacturing method of MEL-treated powder, it was considered important that the mass ratio of the aqueous solvent to the alcohol be 1 or more in order to effectively express the amphiphilic properties of MEL. Therefore, experiments were conducted under conditions where this ratio was varied. In particular, the range of purified water:ethanol = 10:0 to 5:5 was investigated.

[0081] Regarding the stirring temperature, based on the finding that the mobility of MEL molecules increases above 60°C, promoting interaction with the powder surface, we compared two conditions: 60°C and 25°C. 60°C was selected because it is a temperature sufficient to optimize the association state of MEL and is below the boiling point of ethanol (approximately 78°C).

[0082] Furthermore, regarding the filtration process, it was thought that removing excess MEL that was not adsorbed onto the powder surface would result in a MEL-treated powder with a more uniform surface condition. Therefore, the difference in effect with and without the filtration process was investigated.

[0083] [2. Evaluation Method] (water repellency) Tablets for contact angle measurement were prepared by placing 2 g of the MEL-treated powder obtained by the methods of each example and comparative example into a 1 cm diameter mold and compressing it with a compression force of 5 MPa. The prepared tablets were placed in a contact angle measuring device (contact angle meter LSE-B100, manufactured by NIC Corporation), and water droplets were dropped onto the tablets using a syringe. The contact angle (°) formed between the water droplet and the tablet was measured. Generally, a larger contact angle indicates higher water repellency and a higher effect of MEL on modifying the powder surface. High water repellency contributes to improved water resistance of cosmetics and improved adhesion to the skin.

[0084] (Test O / W emulsion foundation) To measure the dispersion stability, feel, and adhesion-free effect described later, a test O / W emulsion foundation was prepared. The formulation and manufacturing process of the test O / W emulsion foundation are as follows.

[0085] [Table 4]

[0086] (1) A portion of No. 6, a portion of No. 7, a portion of No. 8, and a portion of No. 18 shown in Table 4 above were mixed, and Nos. 1 to 5 were added and mixed. For No. 1, "Mannosylerythritol lipid-treated titanium dioxide," the same as that used in Examples 1 to 14 and Comparative Examples 1 to 4 were used, respectively. (2) The mixture from (1) above was dispersed using a three-roll mill to obtain a powder dispersion. (3) A swollen substance was obtained by mixing No. 24-26, a portion of No. 18, and a portion of No. 17. (4) The remaining No. 6, the remaining No. 17, the remaining No. 18, No. 19-20, and the swollen substance from (3) above were mixed and heated to 80°C to obtain an aqueous mixture. (5) The remaining No. 7 and No. 9-16 were mixed and heated to 80°C to obtain an oil-based mixture. (6) Add the oil-based mixture from (5) to the aqueous mixture from (4) above to obtain an emulsion (80°C). (7) The emulsion from (6) above was cooled to 40°C. (8) The powder dispersions from (2) and Nos. 21-23 were added to the emulsion from (7) to obtain a test O / W emulsion type foundation.

[0087] (dispersion stability) The above O / W type foundations were prepared using each example and comparative example, and their stability was confirmed. The condition was observed after being left to stand in a 50°C constant temperature bath for one week. The evaluation criteria are as follows. [Evaluation Criteria] ◎: No powder aggregation is observed. ○: Slight powder aggregation is observed, but redispersion is possible by up-and-down shaking (or mixing with a mixing rod). △: Slight powder aggregation is observed, and redispersion is possible by shaking (or mixing with a mixing rod), but re-aggregation occurs after 24 hours of standing. ×: Aggregation is observed, and redispersion is not possible even with up-and-down shaking (or mixing with a mixing rod).

[0088] (Feeling of use) Using each example and comparative example, the above-mentioned O / W emulsion foundations were prepared and their usability was confirmed. Each foundation was tested by a panel of 20 experts, who evaluated it on a 4-point scale from 0 to 3 points according to the absolute criteria below. The average score was calculated from the sum of all panel scores and judged according to the following criteria (A to D). Specifically, an appropriate amount of each foundation was applied to the skin (inner forearm), and the smoothness of the cosmetic's feel upon application (smooth spreadability) was evaluated. [Evaluation Criteria] Absolute standard 3. I feel it very strongly. 2. Feel 1. Slightly noticeable 0 I don't feel anything ·Judgment criteria A 2.5 points or more B 2 points or more but less than 2.5 points C: 1 point or more, less than 2 points D: Less than 1 point

[0089] (Adhesion-free effect) Using each example and comparative example, the above O / W emulsion type foundations were prepared and their adhesion-free effect was confirmed. An appropriate amount of each foundation was applied to the skin (inner forearm), and after 2 minutes, a tissue was placed over it and the applied area was pressed with the tissue. The transfer of the foundation to the tissue at that time was observed. The evaluation criteria are as follows. [Evaluation Criteria] ◎ No bulk material adheres to the tissue at all. ○ A small amount of foundation was transferred to the tissue (less than 10% of the applied area). △ A small amount of foundation was transferred to the tissue (10-30% of the applied area was affected). × Foundation was transferred to the tissue (more than 30% of the applied area was affected).

[0090] [3. Evaluation Results] Tables 1 to 3 show the measurement results for water repellency (contact angle), dispersion stability, usability, and adhesion-free effect for each example and comparative example. Examples 2 to 4 and 8 to 10, where the mixing ratio of purified water to ethanol was in the range of 9:1 to 7:3, showed excellent results in all items: water repellency (contact angle of 100° or more), dispersion stability (◎ rating), usability (A rating), and adhesion-free effect (◎ or ○ rating). This is thought to be because the amphiphilic properties of MEL were optimally expressed within this mixing ratio range, achieving uniform coating on the powder surface. Furthermore, in Examples 1 and 7, where purified water alone was used as the solvent, high water repellency with a contact angle of 117.8° to 122.2° and good dispersion stability (◎ rating) were confirmed. However, the usability was rated B, which was slightly inferior to the examples in which an appropriate amount of ethanol was added. Furthermore, when the mixing ratio of purified water to ethanol increased to 6:4 to 5:5 (Examples 5-6, 11-12), a decrease in water repellency (contact angle 0°) and a tendency for reduced adhesion-free effect were observed. Thus, it is presumed that if the ethanol ratio is too high, uniform adhesion of MEL to the powder surface is hindered.

[0091] On the other hand, Comparative Examples 1-3, which used ethanol alone, and Comparative Example 4, which used isopropyl alcohol alone, showed poor dispersion stability (rated △ or ×) and relatively inferior usability (rated C or D). This is thought to be because the absence of an aqueous solvent prevented the amphiphilic properties of MEL from being fully expressed, resulting in uneven coating of the powder surface. In particular, Comparative Example 4, which used isopropyl alcohol alone, showed high water repellency with a contact angle of 118.5°, but dispersion stability (rated ×), usability (rated C), and adhesion-free effect (rated ×) were significantly inferior. From the results of these comparative examples, it became clear that product performance (dispersion stability, usability, and adhesion-free effect) cannot be appropriately evaluated based solely on water repellency values.

[0092] Regarding the stirring temperature, in Examples 1-6 and 13-14, which were stirred at 60°C, generally good dispersion stability (rated ○ or ◎) was obtained. In Examples 7-12, which were stirred at 25°C, similarly good dispersion stability (rated ○ or ◎) was obtained under appropriate water:ethanol ratios (10:0 to 7:3). Furthermore, when comparing with the same solvent composition (purified water:ethanol = 7:3), for example, Example 4 (contact angle 113.5°), which was treated at 60°C, showed higher water repellency than Example 10 (contact angle 100.2°), which was treated at 25°C.

[0093] The presence or absence of a filtration process also had an effect. Examples 1 to 12, in which a filtration process was performed, generally showed good adhesion-free effects, whereas Examples 13 to 14, in which a filtration process was not performed, mainly showed inferior adhesion-free effects compared to examples with similar solvent compositions. This is thought to be because the filtration process removed unadsorbed and excessively adsorbed MEL from the surface of the MEL-treated powder, resulting in a more uniform surface condition.

[0094] From the above results, it was confirmed that the method for producing MEL-treated powder according to the present invention, by using an aqueous solvent as the solvent for MEL and adding alcohol as needed, enhances the surface modification effect of the powder by MEL, thereby achieving excellent dispersion stability, a smooth feel, and a non-adhesion effect. In particular, it was confirmed that the functionality of the MEL-treated powder can be more effectively improved by adjusting the mixing ratio of the aqueous solvent and alcohol to an appropriate range of 9:1 to 7:3, setting the stirring temperature to 60°C or higher, and performing a filtration step.

[0095] [4. Examples of cosmetic formulations] As an example of a composition containing MEL-treated powder, we will describe a formulation example of a cosmetic containing MEL-treated powder.

[0096] ■Formulation Example 1: Foundation (Oil-in-Water Emulsion (O / W) type foundation) (component) (mass%) 1. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 1 2.0% 2. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 2 2.0% 3. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 3. 2.0% 4. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 4 2.0% 5. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 5 2.0% 6. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 6 2.0% 7. Red iron oxide 0.2% 8. Yellow iron oxide 0.6% 9. Black iron oxide 0.15% 10. Mica 2.05% 11. Polysorbate 80 1.0% 12. Sorbitan sesquioleate 0.8% 13. Lecithin 0.3% 14. Triceteareth-4 phosphate 0.1% 15. Stearic acid 1.0% 16. Behenyl alcohol 0.4% 17. Cetearyl alcohol 0.4% 18. Glyceryl stearate 0.4% 19. Ethylhexyl Methoxycinnamate 7.0% 20. Diethylamino hydroxybenzoyl hexyl benzoate 0.5% 21. Bis-ethylhexyloxyphenol methoxyphenyl triazine 0.5% 22. Ethylhexyltriazone 0.5% 23. t-Butyl methoxydibenzoylmethane 0.5% 24. Glyceryl tri-2-ethylhexanoate 2.0% 25. Propylene glycol dicaprate 1.0% 26. Mineral oil 3.0% 27. Dimethicone 0.5% 28. Purified water remaining amount 29,1,3-Butylene glycol 12.0% 30. Triethanolamine 1.0% 31. Ethanol 5.0% 32.Fragrance 0.15% 33. Phenoxyethanol 0.1% 34. Carbomer 0.05% 35. (Acrylates / C10-30 Alkyl Acrylate Crosspolymer) 0.15%

[0097] (Manufacturing method) (1) Components 1-10, part of component 11, part of component 12, components 13-14, and part of component 29 were heated and mixed at 60°C to obtain a powder dispersion. (2) A portion of component 28, a portion of component 29, and components 34-35 were mixed at 70°C to obtain a swollen product. (3) The remaining components 12 and 15-27 were heated and mixed at 80°C to obtain a solution (oil phase). (4) The remaining components 11, 28, 29, and 30 described in (2) above were heated and mixed at 80°C to obtain a solution (aqueous phase). (5) Add the solution from (3) above to (4) above and mix to obtain an emulsion. (6) After cooling the above (5), a mixture of components 31 to 33 was added, and then the above (1) was added and mixed to obtain a powder-containing oil-in-water emulsion cosmetic (foundation).

[0098] (evaluation) The foundation in Formulation Example 1 was confirmed to have excellent dispersion stability, a smooth feel, and a non-sticky effect.

[0099] ■Formulation Example 2: Foundation (Oil-in-Water Emulsion (O / W) type foundation) (component) (mass%) 1. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 1 0.5% 2. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 2 0.5% 3. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 3. 0.5% 4. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 4 6.0% 5. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 5 0.5% 6. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 6 0.5% 7. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 7 0.5% 8. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 8 3.0% 9. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 9 0.5% 10. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 10 0.5% 11. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 11 0.5% 12. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 12 0.5% 13. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 13 0.5% 14. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 14 0.5% 15. Red iron oxide 0.3% 16. Yellow iron oxide 0.8% 17. Black iron oxide 0.2% 18. Mica 1.0% 19. Polysorbate 80 1.5% 20. Sorbitan sesquioleate 1.0% 21. Lecithin 0.5% 22. Triceteareth-4 phosphate 0.05% 23. Stearic acid 1.2% 24. Behenyl alcohol 0.3% 25. Cetearyl alcohol 0.5% 26. Glyceryl stearate 0.4% 27. Ethylhexyl Methoxycinnamate 4.0% 28. Diethylamino hydroxybenzoyl hexyl benzoate 0.5% 29. Bis-ethylhexyloxyphenol methoxyphenyl triazine 0.5% 30. Isotridecyl isononanoate 1.0% 31. Polyglyceryl-2 Triisostearate 2.0% 32. Mineral oil 5.0% 33. Dimethicone 1.0% 34. Purified water remaining amount 35,1,3-Butylene glycol 15.0% 36. Triethanolamine 1.1% 37. Ethanol 3.0% 38.Fragrance 0.2% 39. Phenoxyethanol 0.2% 40. Xanthan gum 0.1% 41. (Acrylates / C10-30 Alkyl Acrylate Crosspolymer) 0.20%

[0100] (Manufacturing method) (1) Components 1-18, part of component 19, part of component 20, components 21-22, and part of component 35 were heated and mixed at 60°C to obtain a powder dispersion. (2) A portion of component 34, a portion of component 35, and components 40-41 were mixed at 70°C to obtain a swollen product. (3) The remaining components 20 and 23-33 were heated and mixed at 80°C to obtain a solution (oil phase). (4) The remaining components 19, 34, 35, and 36 described in (2) above were heated and mixed at 80°C to obtain a solution (aqueous phase). (5) Add the solution from (3) above to (4) above and mix to obtain an emulsion. (6) After cooling the above (5), a mixture of components 37 to 39 was added, and then the above (1) was added and mixed to obtain a powder-containing oil-in-water emulsion cosmetic (foundation).

[0101] (evaluation) The foundation in Formulation Example 2 was confirmed to have excellent dispersion stability, a smooth feel, and a non-sticky effect.

[0102] ■Formulation Example 3: Sunscreen (Oil-in-Water Emulsion Type (O / W Type) Sunscreen) (component) (mass%) 1. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 2 0.2% 2. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 4 0.2% 3. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 8. 0.05% 4. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 10 0.05% 5. Polysorbate 80 1.0% 6. Sorbitan sesquioleate 0.8% 7. Stearic acid 1.0% 8. Behenyl alcohol 0.3% 9. Cetearyl alcohol 0.3% 10. Glyceryl stearate 0.3% 11. Ethylhexyl Methoxycinnamate 7.0% 12. Diethylamino hydroxybenzoyl hexyl benzoate 0.5% 13. Bis-ethylhexyloxyphenol methoxyphenyl triazine 2.5% 14. Ethylhexyltriazone 1.5% 15. t-Butyl methoxydibenzoylmethane 0.5% 16. Isononyl Isononanoate 2.0% 17. Propylene glycol dicaprate 1.0% 18. Mineral oil 1.0% 19. Diphenylsiloxy Phenylen Trimethicone 3.0% 20. Dimethicone 0.5% 21. Purified water remaining amount 22,1,3-Butylene glycol 8.0% 23. Dipropylene glycol 5.0% 24. Glyceryl 1.0% 25. Triethanolamine 1.2% 26. Ethanol 4.0% 27.Fragrance 0.2% 28. Phenoxyethanol 0.1% 29. Carbomer 0.02% 30. (Acrylates / C10-30 Alkyl Acrylate Crosspolymer) 0.23% 31. Xanthan gum 0.02% 32. (Sodium acrylate / sodium acryloyldimethyl taurate) copolymer, isohexadecane, polysorbate 80, water mixture 1.0% 33. Aqueous dispersion containing 40% methylenebisbenzotriazolyltetramethylbutylphenol 2.5%

[0103] (Manufacturing method) (1) A powder dispersion was obtained by mixing components 1-4, part of component 5, part of component 6, and part of component 22, and then applying a roller treatment. (2) A portion of component 21, a portion of component 22, and components 29-31 were mixed at 70°C to obtain a swollen product. (3) The remaining components 6 and 7-20 were heated and mixed at 80°C to obtain a solution (oil phase). (4) Add the remaining component 21 to component 32 and mix. Then add the above (2), the remaining component 5, the remaining component 22, and components 23-25 ​​and mix. After heating to 80°C, a solution (aqueous phase) is obtained. (5) Add the solution from (3) above to (4) above and mix to obtain an emulsion. (6) After cooling the above (5), a mixture of components 26 to 28 was added, and then the above (1) was added and mixed to obtain a powder-containing oil-in-water emulsion cosmetic (sunscreen).

[0104] (evaluation) The sunscreen in formulation example 3 was confirmed to have excellent dispersion stability, a smooth feel, and a non-sticky effect.

[0105] ■Formulation Example 4: Foundation (Water-in-Oil Emulsion Type (W / O) Foundation) (component) (mass%) 1. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 1 0.5% 2. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 2 0.5% 3. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 3. 0.5% 4. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 4 6.0% 5. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 5 0.5% 6. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 6 0.5% 7. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 7 0.5% 8. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 8 3.0% 9. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 9 0.5% 10. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 10 0.5% 11. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 11 0.5% 12. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 12 0.5% 13. Mannosylerythritol lipid-treated titanium dioxide prepared according to Example 13 0.5% 14. Mannosylerythritol lipid-treated titanium oxide prepared according to Example 14 0.5% 15. Silicon-treated red iron oxide 0.3% 16. Silicon-treated yellow iron oxide 0.8% 17. Silicon-treated black iron oxide 0.2% 18. Silicon-treated mica 1.0% 19. Polyhydroxystearic acid 0.5% 20. Lecithin 0.5% 21. Lauryl PEG-9 Polydimethylsiloxyethyl Dimethicone 4.0% 22. PEG-9 Polydimethylsiloxyethyl Dimethicone 1.0% 23. Volatile Dimethicone 10.0% 24. Methyl Trimethicone 5.0% 25. Diphenylsiloxy Phenylen Trimethicone 3.0% 26. Ethylhexyl Methoxycinnamate 7.0% 27. Diethylaminohydroxybenzoyl hexyl benzoate 0.5% 28. Bis-ethylhexyloxyphenol methoxyphenyl triazine 0.5% 29. Isododecane 4.0% 30. Glyceryl tri-2-ethylhexanoate 1.0% 31. Dimethicone remaining amount 32. Stearalkonium hectorite 0.4% 33. Disteardimonium hectorite 0.8% 34.Purified water 31.0% 35. Sodium Chloride 0.5% 36,1,3-Butylene glycol 5.0% 37. Ethanol 4.0% 38. Phenoxyethanol 0.2% 39.Fragrance 0.3%

[0106] (Manufacturing method) (1) A powder dispersion was obtained by mixing components 1 to 20, a portion of component 21, a portion of component 22, a portion of component 23, and a portion of component 25, and then applying a roller treatment. (2) By adding components 32-33, a portion of component 22, a portion of component 36, and a portion of component 37, and performing roller treatment, a swollen substance was obtained. (3) After heating and mixing components 26-28, the remaining components 21, 22, 23, 24, 25, and 29-31 were added and mixed. (4) The above (1), above (2), and component 39 were added to (3) and mixed to obtain a solution (oil phase). (5) Mix components 34, 35, the remaining components 36, the remaining components 37, and 38 to obtain a solution (aqueous phase). (6) Add the solution from (5) above to (4) above and mix to obtain a powder-containing water-in-oil emulsion cosmetic (foundation).

[0107] (evaluation) The foundation in formulation example 4 was confirmed to have excellent dispersion stability, a smooth feel, and a non-sticky effect.

[0108] In this specification, embodiments and examples of the present invention have been described with reference to the drawings in order to express the content of the present invention. However, the present invention is not limited to the above embodiments and examples, but includes modifications and improvements that are obvious to those skilled in the art based on the matters described in this specification.

Claims

1. A mixing step to obtain a first mixed solution containing mannosylerythritol lipid (hereinafter referred to as "MEL") and an aqueous solvent, A powder addition step to obtain a second mixed liquid by adding powder to the first mixed liquid, The process includes a drying step of drying the second mixture. A method for producing MEL-treated powder.

2. In the mixing step, the first mixture further contains alcohol A method for producing MEL-treated powder according to claim 1.

3. In the first mixture, the mass ratio of the aqueous solvent to the alcohol is 1 or more. A method for producing MEL-treated powder according to claim 2.

4. In the powder addition step, the temperature of the first mixture when adding the powder is 60°C or higher and below the boiling point of the alcohol. A method for producing MEL-treated powder according to claim 2.

5. The aforementioned powder is one or more selected from titanium oxide, zinc oxide, and iron oxide. A method for producing MEL-treated powder according to claim 4.

6. The aforementioned powder is one or more selected from titanium oxide, zinc oxide, and iron oxide. A method for producing MEL-treated powder according to claim 1.

7. After the powder addition step and before the drying step, the process further includes a filtration step in which the second mixture is filtered to separate it into a filtrate and a filtrate. In the drying step, the filtered material is dried. A method for producing MEL-treated powder according to claim 1.

8. After the mixing step and before the powder addition step, the process further includes a stirring step in which the first mixture, heated to 60°C or higher and below the boiling point of the aqueous solvent, is stirred. A method for producing MEL-treated powder according to claim 1.

9. A step of obtaining the MEL-treated powder by the manufacturing method described in claim 1, The process includes manufacturing a composition containing the aforementioned MEL-treated powder. A method for producing the MEL-treated powder-containing composition.

10. MEL-treated powder obtained by the manufacturing method described in claim 1.

11. A composition containing the MEL-treated powder described in claim 10.

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