Spherical microparticles of cellulose ether with low degree of substitution, cosmetic composition using same, and method for producing spherical microparticles of cellulose ether with low degree of substitution

Abstract

The purpose of the present invention is to provide spherical microparticles of cellulose ether having a low degree of substitution, which can contribute to improving the feeling of use of a cosmetic composition to be used regardless of whether or not carbon disulfide is used. The purpose is achieved by spherical cellulose ether microparticles having a low degree of substitution in which the volume-based average particle diameter (D50) of primary particles measured by dry laser diffraction is 1-30 [mu] m, the true sphericity is 0.75-1.0, and the surface smoothness is 75-100%.

Description

Technical Field

[0001] This invention relates to low-substituted cellulose ether spherical microparticles, cosmetic compositions using the same, and a method for manufacturing low-substituted cellulose ether spherical microparticles. Background Technology

[0002] Due to their particle properties, spherical microparticles are used in various fields as matting agents, lubricants, and anti-blocking agents. Additionally, they are used in cosmetics to improve properties such as extensibility. However, in recent years, due to environmental problems such as marine pollution caused by microplastics, the composition of spherical microparticles in cosmetics has gradually shifted from petroleum-derived synthetic materials to naturally derived materials.

[0003] As spherical microparticles composed of natural raw materials, Japanese Patent Application Publication No. 5-200286 (Patent Document 1) and Japanese Patent Application Publication No. 11-181147 (Patent Document 2) disclose methods for manufacturing spherical microparticles by coagulating and regenerating a viscose liquid made from cellulose, a natural raw material. Furthermore, Japanese Patent Application Publication No. 2003-252902 (Patent Document 3) discloses a method for obtaining spherical microparticles by spray drying a dispersion composed of a low-substituted cellulose ether.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 5-200286

[0007] Patent document 2 Japanese Patent Application Publication No. 11-181147

[0008] Patent document 3 Japanese Patent Application Publication No. 2003-252902 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, the methods described in Patent Documents 1 and 2 are not preferred from the viewpoint of environmental impact because carbon disulfide, which may pollute the environment, is used in order to manufacture the adhesive liquid.

[0011] Furthermore, in the method described in Patent Document 3, the rapid evaporation of water in the low-substituted cellulose ether dispersion through spray drying causes particle shrinkage, making it difficult to obtain spherical microparticles with high sphericity and surface smoothness. As a result, the cosmetic composition containing spherical microparticles obtained by the method described in Patent Document 3 has insufficient tactile feel and spreadability on the skin when applied, resulting in a poor user experience.

[0012] Therefore, in view of the above, the problem to be solved by the present invention is to provide a low degree of substitution cellulose ether spherical microparticle that, regardless of whether carbon disulfide is used, can help improve the user experience of the cosmetic composition used.

[0013] Methods for solving problems

[0014] In order to solve the above-mentioned problems, the inventors conducted in-depth research and repeatedly tried and tested methods for obtaining spherical microparticles of low-substituted cellulose ethers using raw materials with low environmental impact. As a result, the inventors obtained a W / O type emulsion of low-substituted cellulose ethers composed of raw materials with low environmental impact, and then subjected it to precipitation and coagulation treatment, thereby successfully obtaining spherical microparticles of low-substituted cellulose ethers.

[0015] Surprisingly, the low-substituted cellulose ether spherical microparticles obtained in this way have a small average particle size, high sphericity, and high surface smoothness. Based on these characteristics, cosmetic compositions using these low-substituted cellulose ether spherical microparticles exhibit excellent skin spreadability and moisturizing properties, resulting in a superior user experience. Even more surprisingly, this excellent user experience is achieved even with relatively small amounts of the low-substituted cellulose ether spherical microparticles.

[0016] As a result, and as a technical means to solve the problem of this invention, the inventors have finally succeeded in producing low-substituted cellulose ether spherical microparticles with average particle size, true sphericity, and surface smoothness within specified ranges. This invention is based on insights and successful examples first discovered by the inventors.

[0017] Therefore, according to various aspects of the present invention, low-substituted cellulose ether spherical microparticles and cosmetic compositions using the same are provided, as well as methods for manufacturing low-substituted cellulose ether spherical microparticles.

[0018] [1] Low-substituted cellulose ether spherical microparticles, the average particle size (D) of the primary particles was determined using dry laser diffraction as a volume reference. 50 The surface area is 1μm to 30μm, the sphericity is 0.75 to 1.0, and the surface smoothness is 75% to 100%.

[0019] [2] Further, according to the low-substituted cellulose ether spherical particles described in item [1], the low-substituted cellulose ether has a molar degree of substitution of 0.05 to 1.0.

[0020] [3] A cosmetic composition comprising low-substituted cellulose ether spherical microparticles and an oil as described in entry [1] or entry [2].

[0021] [4] The cosmetic composition described in entry [3] also contains water.

[0022] [5] The method for manufacturing low-substituted cellulose ether spherical microparticles as described in item [1] or [2] comprises:

[0023] In step (1), the alkaline aqueous solution of the low-substituted cellulose ether as raw material and the non-water-soluble solvent are mixed at a volume ratio of 1:99 to 40:60 to obtain a W / O type low-substituted cellulose ether emulsion.

[0024] Step (2) involves mixing the acidic aqueous solution and the insoluble solvent as raw materials at a volume ratio of 1:99 to 40:60 to obtain a W / O type acidic aqueous solution emulsion; and

[0025] In step (3), the W / O type low-substitution degree cellulose ether emulsion is mixed with the W / O type acidic aqueous solution emulsion to obtain the low-substitution degree cellulose ether spherical particles described in item [1] or [2].

[0026] [6] In the method for manufacturing low-substituted cellulose ether spherical microparticles according to entry [5], the raw materials of step (1) further include surfactants; and / or, the raw materials of step (2) further include surfactants.

[0027] [7] In the method for manufacturing low-substituted cellulose ether spherical microparticles according to entry [5], the non-water-soluble solvent is independently selected from at least one non-water-soluble solvent selected from silicone oil and hydrocarbon solvents having 5 to 10 carbon atoms.

[0028] The effects of the invention

[0029] According to the present invention, by using low-substituted cellulose ether spherical microparticles with physical properties such as average particle size, sphericity, and surface smoothness within a specified range, cosmetic compositions with excellent user experience can be obtained. In particular, cosmetic compositions using the aforementioned spherical microparticles exhibit excellent spreadability and moisturizing properties on the skin. Detailed Implementation

[0030] The present invention will now be described in detail, but various methods may be used to achieve its purpose.

[0031] The terms used in this specification are used in the sense commonly used by those skilled in the art, such as in the fields of cosmetics and chemistry, unless otherwise specified, and should not be construed as having an improper limiting meaning. Furthermore, since the speculations and theories made in this specification are based on the inventors' insights and experience to date, the invention is not solely bound by these speculations and theories.

[0032] The term "composition" is used in a general sense without particular limitation; for example, it refers to a substance composed of two or more ingredients (raw materials). Each ingredient can be a single, individual ingredient or a combination of two or more ingredients.

[0033] The term "and / or" refers to any one or more of the listed related items, or any combination of all of them.

[0034] "Content" is synonymous with concentration and usage (addition amount), and refers to the proportion of an ingredient relative to the total amount in the composition. The total content of an ingredient shall not exceed 100%.

[0035] The "~" sign for a numerical range includes the range of values ​​preceding and following it, excluding any boundary values. For example, "0% to 100%" can be any of the following: above 0%, below 100%, or above 0% and below 100%. "More than" and "less than" do not include the following value; they refer to the lower and upper limits, respectively. For example, "more than 1" means a value greater than 1, and "less than 100" means a value less than 100. "Approximately" refers to a quantity within ±10% of the quantity followed by the term. For example, "approximately 100" means 100 ± 10%, that is, 90 to 110.

[0036] "Including" means that elements other than those explicitly stated as included can be added (synonymous with "at least included"), but includes "composed of" and "essentially constituted by". That is, "including" can refer to including explicitly stated elements as well as any one or more of the explicitly stated elements, and can refer to being composed of explicitly stated elements or essentially constituting by explicitly stated elements. Elements can be enumerated as: ingredients, processes, conditions, parameters, and other limiting matters, etc.

[0037] The number of digits in an integer value is the same as the number of significant digits. For example, 1 has one significant digit, and 10 has two significant digits. Similarly, the number of digits after the decimal point in a decimal value is the same as the number of significant digits. For example, 0.1 has one significant digit, and 0.10 has two significant digits.

[0038] The "skin feel" of a cosmetic composition refers to the minimal stickiness or other discomfort it causes when applied and spread on the skin.

[0039] The "spreadability on the skin" of a cosmetic composition refers to the ability of the cosmetic composition to be applied and spread smoothly on the skin without applying significant force.

[0040] The "moisturizing property" of a cosmetic composition refers to the skin's hydration level 5 minutes after the cosmetic composition has been applied to the skin.

[0041] [Low-substitution degree cellulose ether spherical microparticles]

[0042] One aspect of the present invention is low-substituted cellulose ether spherical microparticles. One type of low-substituted cellulose ether spherical microparticles is characterized by the average particle size (D0) of the primary particles, measured using dry laser diffraction as a volume reference. 50 The sphericity and surface smoothness are within the specified range.

[0043] Low-substituted cellulose ethers are insoluble in water but soluble in alkaline solutions. Generally, cellulose is insoluble in water. In contrast, cellulose ethers formed by replacing the hydrogen atoms of the hydroxyl groups in the glucose ring of cellulose with functional groups such as alkyl or hydroxyalkyl groups become water-soluble depending on the degree of substitution. However, low-substituted cellulose ethers tend to be insoluble in water but soluble in alkaline solutions. Furthermore, low-substituted cellulose ethers can be regenerated from alkaline solutions by adding acid to neutralize and solidify them. These low-substituted cellulose ethers, while insoluble in water, exhibit water-absorbing and swelling properties.

[0044] In summary, low-substituted cellulose ethers have the following properties (1) to (4): (1) insoluble in water; (2) swells upon absorbing water; (3) soluble in alkaline solutions; and (4) can be regenerated from alkaline solutions by neutralization and coagulation with acid.

[0045] The average particle size (D) of primary particles of low-substituted cellulose ether spherical microparticles of one embodiment of the present invention, determined by dry laser diffraction, on a volume-based basis. 50 The particle size is 1 μm to 30 μm, the sphericity is 0.75 to 1.0, and the surface smoothness is 75% to 100%. In this specification, substances whose average particle size, sphericity, and surface smoothness fall within the above ranges are referred to as "spherical microparticles." In other words, substances whose average particle size, sphericity, or surface smoothness does not fall within the above ranges cannot be called spherical microparticles.

[0046] Examples of low-substituted cellulose ethers that constitute spherical microparticles of low-substituted cellulose ethers include low-substituted hydroxypropyl cellulose, low-substituted hydroxyethyl cellulose, low-substituted methyl cellulose, and low-substituted hydroxypropyl methyl cellulose. However, from the viewpoint of good alkali solubility and water absorption and swelling properties, low-substituted hydroxypropyl cellulose is preferred.

[0047] The present invention provides a method for the production of low-substituted cellulose ether spherical microparticles, wherein the average particle size of the primary particles is determined using dry laser diffraction as a volume-based average particle size (D0). 50The particle size can be 1 μm to 30 μm, but, for example, from the viewpoint of excellent spreadability and moisturizing properties on the skin when used in cosmetic compositions, 1 μm to 25 μm is preferred, 1 μm to 22 μm is more preferred, 1 μm to 20 μm is even more preferred, and 7 μm to 15 μm is even more preferred. The average particle size of the primary particles is determined by the method described in the entry <Average Particle Size of Primary Particles> in the examples described later, by irradiating the particles after the powder sample is ejected with compressed air with a laser, and measuring the volume-converted average particle size based on the diffraction intensity.

[0048] In one embodiment of the present invention, the true sphericity of the low-substituted cellulose ether spherical microparticles is only required to be 0.75 to 1.00. However, from the viewpoint of excellent spreadability and moisturizing properties on the skin when used in cosmetic compositions, a true sphericity of 0.78 to 1.00 is preferred, more preferably 0.80 to 1.00, further preferably 0.82 to 1.00, and even more preferably 0.85 to 1.00. The true sphericity is determined by the method described in the entry "True Sphericity" of the examples described later.

[0049] In one embodiment of the present invention, the surface smoothness of the spherical microparticles of the low-substituted cellulose ether is 75% to 100%. However, from the viewpoint of excellent spreadability and moisturizing properties on the skin when used in cosmetic compositions, 78% to 100% is preferred, more preferably 80% to 100%, further preferably 82% to 100%, and even more preferably 85% to 100%. The surface smoothness is determined by the method described in the entry "Surface Smoothness" in the examples described later.

[0050] The low-substituted cellulose ether spherical microparticles of one embodiment of the present invention may possess other physical properties besides the average particle size, true sphericity, and surface smoothness of the primary particles, without hindering the resolution of the problem of the present invention. These other physical properties are not particularly limited, and examples include aspect ratio, substituent content, and molar degree of substitution.

[0051] In the low-substituted cellulose ether spherical microparticles of one embodiment of the present invention, the aspect ratio is preferably 1.00 to 1.30, more preferably 1.00 to 1.20, and even more preferably 1.00 to 1.15, which is related to high sphericity. The aspect ratio is determined by the method described in the entry <Aspect Ratio> in the examples described later.

[0052] From the viewpoint of being insoluble in water and soluble in alkali, the molar degree of substitution of the low-substituted cellulose ether spherical particles of one embodiment of the present invention is preferably 0.05 to 1.0, more preferably 0.05 to 0.8, and even more preferably 0.1 to 0.6, 0.1 to 0.5, or 0.1 to 0.4. The molar degree of substitution refers to the total average number of moles of hydroxyalkoxy and alkyl groups per mole of anhydrous glucose. For example, the molar degree of substitution of the low-substituted hydroxypropyl cellulose ether spherical particles can be obtained by converting the value determined using the quantitative method described in the entry "Low-substituted hydroxypropyl cellulose" in the 18th revised edition of the Japanese Pharmacopoeia. Furthermore, the molar degree of substitution of the low-substituted cellulose ether spherical particles is equivalent to the molar degree of substitution of the low-substituted cellulose ether used as a raw material.

[0053] [Method for manufacturing low-substitution degree cellulose ether spherical microparticles]

[0054] One embodiment of the present invention provides cellulose ether spherical microparticles, for example, by mixing an alkaline aqueous solution of a low-substituted cellulose ether with an insoluble solvent at a volume ratio of 1:99 to 40:60 to obtain a water-in-oil (W / O) type low-substituted cellulose ether emulsion, and by mixing an acidic aqueous solution with an insoluble solvent at a volume ratio of 1:99 to 40:60 to obtain a W / O type acidic aqueous solution emulsion, and then mixing the two emulsions.

[0055] Another aspect of the present invention is a method for manufacturing cellulose ether spherical microparticles according to one embodiment of the present invention. The manufacturing method according to one embodiment of the present invention includes the following steps (1) to (3):

[0056] (1) A process of mixing an alkaline aqueous solution of a low degree of substitution cellulose ether as a raw material with an insoluble solvent at a volume ratio of 1:99 to 40:60 to obtain a W / O type low degree of substitution cellulose ether emulsion.

[0057] (2) The process of mixing the acidic aqueous solution and the insoluble solvent as raw materials at a volume ratio of 1:99 to 40:60 to obtain a W / O type acidic aqueous solution emulsion; and

[0058] (3) A process of mixing a W / O type low-substitution degree cellulose ether emulsion with a W / O type acidic aqueous solution emulsion to obtain low-substitution degree cellulose ether spherical particles according to one embodiment of the present invention.

[0059] In one aspect of the manufacturing method of the present invention, step (2) may be performed after step (1), step (1) may be performed after step (2), or steps (1) and (2) may be performed in parallel. Step (3) is performed after steps (1) and (2).

[0060] [Process (1): Preparation of W / O type low-substitution degree cellulose ether emulsion]

[0061] The main raw materials in process (1) are an alkaline aqueous solution of low-substituted cellulose ether and a non-water-soluble solvent.

[0062] The alkaline aqueous solution of low-substituted cellulose ether is obtained by uniformly dissolving the low-substituted cellulose ether in an alkaline aqueous solution.

[0063] Examples of bases in alkaline aqueous solutions include hydroxides of sodium hydroxide, potassium hydroxide, and ammonium hydroxide; organic amine bases such as monoethanolamine, aminomethylpropanol, aminomethylpropanediol, tris(hydroxymethyl)aminomethane (Tris), and tetrahydroxypropylethylenediamine. From the viewpoint of solubility of cellulose ethers with low degree of substitution, sodium hydroxide is preferred.

[0064] For example, from the viewpoint of the solubility of low-substituted cellulose ethers, the alkali concentration of the alkaline aqueous solution is preferably 0.1% to 30% by mass, more preferably 0.3% to 25% by mass, even more preferably 0.5% to 20% by mass, and even more preferably 1% to 15% by mass.

[0065] For example, from the viewpoint of the viscosity of the alkaline aqueous solution, the content of the low-substituted cellulose ether in the alkaline aqueous solution of the low-substituted cellulose ether is preferably 0.1% to 20% by mass, more preferably 0.5% to 17% by mass, further preferably 1% to 15% by mass, and even more preferably 1% to 10% by mass or 3% to 7% by mass.

[0066] Non-water-soluble solvents are simply oily solvents that have very low or no miscibility with water, such as silicone oil and hydrocarbon solvents with 5 to 10 carbon atoms.

[0067] Examples of silicone oils include: linear or branched organopolysiloxanes ranging from low to high viscosity, such as polydimethylsiloxane, tris(trimethylsiloxy)methylsilane, octyl polymethylsiloxane, phenyltrimethylsiloxane, tetra(trimethylsiloxy)silane, methylphenylpolysiloxane, methylhexylpolysiloxane, methylhydropolysiloxane, and dimethylsiloxane-methylphenylsiloxane copolymers; cyclic organopolysiloxanes such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecylcyclohexasiloxane, tetramethyltetrahydrocyclotetrasiloxane, and tetramethyltetraphenylcyclotetrasiloxane; advanced alkoxy-modified silicone oils such as amino-modified organopolysiloxane, pyrrolidone-modified organopolysiloxane, pyrrolidone carboxylic acid-modified organopolysiloxane, and stearoxy-modified silicone oil; and advanced fatty acid-modified silicone oils, alkyl-modified silicone oils, long-chain alkyl-modified silicone oils, amino acid-modified silicone oils, and fluorine-modified silicone oils.

[0068] Examples of hydrocarbon solvents with 5 to 10 carbon atoms include: pentane, isopentane, neopentane, hexane, cyclohexane, isohexane, heptane, octane, nonane, and decane.

[0069] The alkaline aqueous solution of the low-substituted cellulose ether and the insoluble solvent are mixed in a ratio that forms a W / O type emulsion. For example, from the viewpoint of microemulsion formation, their mixing volume ratio ([alkaline aqueous solution of low-substituted cellulose ether]: [insoluble solvent]) is preferably 1:99 to 40:60, more preferably 3:97 to 38:62, even more preferably 5:95 to 36:64, and even more preferably 10:90 to 35:65.

[0070] In step (1), surfactants are preferably used as other raw materials for the purpose of stabilizing the emulsion.

[0071] There are no particular limitations on surfactants as long as they are commonly used as components in cosmetic compositions. Examples include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.

[0072] Examples of nonionic surfactants include: polyether-modified silicone oil; polyglycerol-modified silicone oil; acrylic silicone oil; polyoxyethylene sorbitan monostearate; sorbitan oleate; sorbitan sesquiisostearate and other sorbitan fatty acid esters; and hardened castor oil derivatives.

[0073] Examples of anionic surfactants include: fatty acid salts such as sodium lauryl sulfate; higher alkyl sulfate salts such as sodium lauryl sulfate; alkyl ether sulfate salts such as polyoxyethylene lauryl sulfate triethanolamine; N-acylsarcosine salts; sulfosuccinates; N-acyl amino acid salts, etc.

[0074] Examples of cationic surfactants include: alkyltrimethylammonium salts such as octadecyltrimethylammonium chloride; benzalkonium chloride; benzyl chloride, etc.

[0075] Examples of amphoteric surfactants include betaine surfactants such as alkyl betaine and amide betaine.

[0076] For example, from the viewpoint of emulsion stabilization, the amount of surfactant used as an external addition is preferably 0.01 vol% to 10 vol%, more preferably 0.01 vol% to 9 vol%, further preferably 0.01 vol% to 8 vol%, and even more preferably 0.05 vol% to 0.5 vol%, relative to the total amount of alkaline aqueous solution of low-substituted cellulose ether and non-water-soluble solvent used.

[0077] The raw materials are preferably mixed by stirring. Stirring can be done manually or by equipment, but equipment stirring with a stirring and mixing device is preferred in order to form a stable emulsion.

[0078] Examples of mixing and blending devices include: homogenizers (e.g., "MARKII 2.5 type homogenizer", manufactured by Primix); homogenizing dispersers (e.g., "2.5 type homogenizing disperser", manufactured by Primix); homogenizers (e.g., "Ace homogenizer", manufactured by Nippon Seiki Co., Ltd.); emulsifying dispersers (e.g., "2M-03 type", manufactured by Primix); multi-shaft dispersing mixers (e.g., "CombiMix", manufactured by Primix); and colloid mills (e.g., "colloid mill MM-2", manufactured by Nippon Seiki Co., Ltd.).

[0079] The stirring using a mixing device can be carried out as long as it is under conditions that can produce a W / O type low-substitution degree cellulose ether emulsion. For example, when using a homogenizer, from the viewpoint of forming a microemulsion, the rotor speed during mixing is preferably 1000 rpm to 10000 rpm, more preferably 5000 rpm to 10000 rpm; the mixing time is preferably 3 minutes to 60 minutes, more preferably 10 minutes to 30 minutes.

[0080] In step (1), other raw materials may be used besides alkaline aqueous solutions of low-substituted cellulose ethers, non-water-soluble solvents, and surfactants. However, it is preferable not to use environmentally polluting substances as other raw materials, and more preferably not to use carbon disulfide.

[0081] [Process (2): Preparation of W / O type acid aqueous solution emulsion]

[0082] The main raw materials in process (2) are acidic aqueous solution and non-water-soluble solvent.

[0083] Examples of acids that can be used in acidic aqueous solutions include inorganic acids such as hydrochloric acid and sulfuric acid; organic acids such as citric acid, oxalic acid, and malic acid; but hydrochloric acid is preferred.

[0084] In order to stably coagulate and precipitate spherical particles of low-substituted cellulose ether by mixing a W / O emulsion of an alkaline aqueous solution of low-substituted cellulose ether with a W / O emulsion of an acidic aqueous solution, for example, the acid concentration in the acidic aqueous solution is preferably 1% to 50% by mass, more preferably 3% to 30% by mass, and even more preferably 5% to 20% by mass.

[0085] From the viewpoint of promoting the formation of low-substituted cellulose ether spherical particles, the acidic aqueous solution is preferably set such that the salt concentration is within a specified range. For example, when hydrochloric acid is used as the acid, it is preferable that the acidic aqueous solution contains sodium chloride. In this case, the final concentration of sodium chloride contained in the acidic aqueous solution is preferably 1% to 20% by mass, more preferably 5% to 15% by mass.

[0086] The non-water-soluble solvent can refer to the non-water-soluble solvent described in step (1). The non-water-soluble solvent can be the same as or different from the solvent used in step (1), but the same solvent is preferred in order to stably form low-substituted cellulose ether spherical particles.

[0087] The acid-water solution and the insoluble solvent are mixed in a ratio that forms a W / O type emulsion. For example, from the viewpoint of microemulsion formation, their mixing volume ratio ([acid-water solution]:[insoluble solvent]) is preferably 1:99 to 40:60, more preferably 3:97 to 38:62, even more preferably 5:95 to 36:64, and even more preferably 10:90 to 35:65.

[0088] In step (2), similarly to step (1), a surfactant is preferably used as another raw material for the purpose of stabilizing the emulsion. The surfactant can refer to the surfactant described in step (1). The surfactant can be the same as or different from the surfactant used in step (1), but the same surfactant is preferred in order to stably form low-substituted cellulose ether spherical particles.

[0089] For example, from the viewpoint of emulsion stabilization, the amount of surfactant used as an external addition is preferably 0.01 vol% to 10 vol%, more preferably 0.01 vol% to 9 vol%, further preferably 0.01 vol% to 8 vol%, and even more preferably 0.05 vol% to 0.5 vol%, relative to the total amount of acidic aqueous solution and non-water-soluble solvent used.

[0090] The raw materials are preferably mixed by stirring. Stirring can be done manually or by equipment, but equipment stirring with a stirring and mixing device is preferred in order to form a stable emulsion. The types and conditions of use of stirring and mixing devices can be referred to the types and conditions of use of stirring and mixing devices described in step (1).

[0091] In step (2), other raw materials may be used besides acidic aqueous solutions, non-water-soluble solvents, and surfactants. However, it is preferable not to use environmentally polluting substances as other raw materials, and more preferably not to use carbon disulfide.

[0092] [Process (3): Formation of low-substituted cellulose ether spherical microparticles]

[0093] The main raw materials in process (3) are the product of process (1), namely W / O type low-substitution degree cellulose ether emulsion and the product of process (2), namely W / O type acidic aqueous solution emulsion.

[0094] The W / O type low-substituted cellulose ether emulsion and the W / O type acidic aqueous solution emulsion are mixed at a ratio that forms low-substituted cellulose ether spherical particles. For example, from the viewpoint of the formation of fine spherical particles, their mixing volume ratio ([W / O type low-substituted cellulose ether emulsion]:[W / O type acidic aqueous solution emulsion]) is preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40.

[0095] A W / O type low-substituted cellulose ether emulsion and a W / O type acidic aqueous solution emulsion are mixed to form low-substituted cellulose ether spherical particles. From the viewpoint of obtaining fine spherical particles, for example, it is preferable to mix the W / O type low-substituted cellulose ether emulsion with the W / O type acidic aqueous solution emulsion by slowly adding the W / O type low-substituted cellulose ether emulsion while mechanically stirring the W / O type acidic aqueous solution emulsion using a stirring mixing device.

[0096] The mixing device can refer to the mixing device described in step (1).

[0097] The stirring using a mixing device can be carried out under conditions that allow for the production of spherical particles of cellulose ether with a low degree of substitution. From the viewpoint of obtaining fine spherical particles, for example, when using a homogenizer, the rotor speed during mixing is preferably 1000 rpm to 10000 rpm, more preferably 2000 rpm to 4000 rpm.

[0098] From the viewpoint of the formation of fine spherical particles, the time for adding W / O type low-substituted cellulose ether emulsion to W / O type acidic aqueous emulsion is preferably 3 to 60 minutes, more preferably 10 to 30 minutes.

[0099] In step (3), preferably, after adding the W / O type low-substituted cellulose ether emulsion to the W / O type acidic aqueous emulsion, the resulting mixture is further stirred. The stirring conditions for the mixture of the W / O type acidic aqueous emulsion and the W / O type low-substituted cellulose ether emulsion are suitable as long as they allow the low-substituted cellulose ether spherical particles to fully coagulate and precipitate. For example, when using the above-mentioned stirring and mixing device or other devices such as a magnetic stirrer, the rotation speed is preferably 500 to 3000 rpm, and the stirring time is preferably 30 minutes to 5 hours, more preferably 2 hours to 5 hours.

[0100] The low-substituted cellulose ether spherical particles that precipitate out during coagulation can be recovered, for example, through solid-liquid separation processes such as filtration. The recovered low-substituted cellulose ether spherical particles can also undergo other processing such as drying.

[0101] [Cosmetic Compositions]

[0102] Another aspect of the present invention is a cosmetic composition. One embodiment of the cosmetic composition of the present invention is characterized by comprising, as constituent components, low-substituted cellulose ether spherical microparticles and an oil agent according to one embodiment of the present invention.

[0103] A cosmetic composition according to one aspect of the present invention, comprising low-substituted cellulose ether spherical microparticles according to one aspect of the present invention, exhibits excellent skin feel, spreadability on the skin, and moisturizing properties, resulting in an overall superior user experience.

[0104] From the viewpoint of the skin-applying properties of the cosmetic composition, the content of low-substituted cellulose ether spherical microparticles is not particularly limited. For example, relative to the total amount of the cosmetic composition, it is preferably 0.01% to 20% by mass, more preferably 0.1% to 15% by mass, even more preferably 0.5% to 10% by mass, and even more preferably 1% to 7% by mass.

[0105] Oils can be any oils commonly used in the manufacture of cosmetic compositions, such as hydrocarbon oils, ester oils, animal and vegetable oils, silicone oils, etc.

[0106] Examples of hydrocarbon oils include: liquid paraffin, stearic acid, hydrogenated polyisobutylene, hydrogenated polydecene, squalane, squalene, squalane, squalane, light isoparaffins, light liquid isoparaffins, heavy liquid isoparaffins, liquid isoparaffins, tetradecene, isohexadecane, isodecane, α-olefin oligomers, etc.

[0107] Examples of ester oils include: glyceryl stearate, ethyl oleate, ethyl linoleate, isopropyl myristate, isopropyl palmitate, isopropyl isostearate, cetyl 2-ethylhexanoate, isocetyl 2-ethylhexanoate, stearyl 2-ethylhexanoate, isostearyl 2-ethylhexanoate, cetyl palmitate, 2-ethylhexyl palmitate, 2-hexyldecyl isostearate, isostearate, trimethylolpropane triisostearate, tetradecyl myristate, cetyl myristate, octyl dodecyl myristate, isostearyl myristate, hexyl laurate, decyl oleate, octyl dodecyl oleate, isostearyl neopentanoate, isopropyl isostearate, and isononyl isononanoate. 2-Ethylhexyl isononanoate, isodecanoate isonononanoate, isotriadecyl isonononanoate, octyldodecyl erucate, neopentyl glycol didecanoate, pentaerythritol tetraethylhexanoate, diisostearyl malate, trimethylolpropane triethylhexanoate, didecyl adipate, cholesterol isostearate, butyl isostearate, hydrogenated castor oil monohydroxystearate, lanolin fatty acid isostearyl alcohol ester, lanolin fatty acid isopropyl ester, lanolin fatty acid octyldodecyl ester, cetyl ricinoleate, dioctyl succinate, cetyl lactate, propylene glycol dioctanoate, propylene glycol didecanoate, propylene glycol dinonanoate, di(octanoic acid / decanoic acid) propylene glycol, propylene glycol diisostearate, propylene glycol dioleate, triglycerides, animal and vegetable oils, etc. Examples of triglycerides include: triglycerides of glycerol, hexanoic acid, caprylic acid, capric acid, 2-ethylhexanoic acid, isotretinoic acid, isopalmitic acid, isostearic acid, arachidic acid, oleic acid, etc.

[0108] Examples of animal and vegetable oils include: liquid lanolin, olive oil, sunflower seed oil, safflower oil, castor oil, and camellia oil.

[0109] Examples of silicone oils include: linear or branched organopolysiloxanes ranging from low to high viscosity, such as polydimethylsiloxane, tris(trimethylsiloxy)methylsilane, octyl polymethylsiloxane, phenyltrimethylsiloxane, tetra(trimethylsiloxy)silane, methylphenylpolysiloxane, methylhexylpolysiloxane, methylhydropolysiloxane, and dimethylsiloxane-methylphenylsiloxane copolymers; cyclic organopolysiloxanes such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecylcyclohexasiloxane, tetramethyltetrahydrocyclotetrasiloxane, and tetramethyltetraphenylcyclotetrasiloxane; advanced alkoxy-modified silicone oils such as amino-modified organopolysiloxane, pyrrolidone-modified organopolysiloxane, pyrrolidone carboxylic acid-modified organopolysiloxane, and stearoxy-modified silicone oil; and advanced fatty acid-modified silicone oils, alkyl-modified silicone oils, long-chain alkyl-modified silicone oils, amino acid-modified silicone oils, and fluorine-modified silicone oils.

[0110] The content of the oil is not particularly limited. For example, from the viewpoint of the moisturizing properties of the cosmetic composition, it is preferably 0.1% to 50% by mass relative to the total amount of the cosmetic composition, more preferably 0.3% to 45% by mass, even more preferably 0.5% to 40% by mass, and even more preferably 1% to 35% by mass.

[0111] The cosmetic composition of the present invention may also contain water.

[0112] There are no particular limitations on the water used in the manufacture of cosmetic compositions, such as tap water and purified water, but purified water is preferred from the viewpoint of being free of impurities.

[0113] The water content is not particularly limited, as long as it is the amount normally used in cosmetic compositions, depending on the dosage form of the cosmetic composition. For example, from the viewpoint of the skin-applying properties of the cosmetic composition, it is preferably 90% by mass or less, more preferably 85% by mass or less, further preferably 80% by mass or less, and even more preferably 75% by mass or less relative to the total amount of the cosmetic composition. The lower limit of the water content is typically 0% by mass. Taking these considerations into account, the water content is preferably 0% by mass to 90% by mass, more preferably 10% by mass to 85% by mass, further preferably 20% by mass to 80% by mass, and even more preferably 30% by mass to 75% by mass.

[0114] To achieve the desired properties, cosmetic compositions may contain other ingredients besides low-substituted cellulose ether spherical particles, oils, and water. Examples of such other ingredients include: solvents, surfactants, pH adjusters, clay minerals, colorants, thickeners, antioxidants, preservatives, humectants, pearlescent agents, astringents, whitening agents, fragrances, and other additives. Specific examples of various additives are listed below.

[0115] Specific examples of solvents include: polyols such as glycerol, diglycerol, butanediol, propylene glycol, and dipropylene glycol; alcohols such as ethanol.

[0116] There are no particular limitations on the surfactant as long as it is a surfactant commonly used as a component of cosmetic compositions, for example, the surfactant described in step (1) can be referred to.

[0117] Specific examples of pH adjusters include: ethanolamine, diethanolamine, triethanolamine, citric acid, sodium citrate, gluconic acid, succinic acid, sodium hydroxide, potassium hydroxide, etc.

[0118] Specific examples of clay minerals include: talc, mica, sericite, kaolin, montmorillonite, saponite, lithium saponite, chlorite, etc.

[0119] Specific examples of colorants include: iron oxide red, iron oxide yellow, iron oxide black, titanium oxide, ultramarine, dark blue, manganese violet, cobalt violet, chromium hydroxide, chromium oxide, cobalt oxide, cobalt titanate, iron-doped titanium oxide, iron titanate, titanium / titanium dioxide calcined products, lithium / cobalt titanate, cobalt titanate, titanium nitride, iron hydroxide, γ-iron oxide, and other inorganic brown pigments; ochre and other inorganic yellow pigments; substances formed by laked tar-based pigments; substances formed by laked natural pigments, and other colored pigments. The shape of the pigment can be any of the following: spherical, roughly spherical, rod-shaped, spindle-shaped, petal-shaped, long strips or flakes, irregular, etc. As long as it imparts color to the formulation, its geometric shape is not particularly limited.

[0120] Specific examples of thickeners include: xanthan gum, guar gum, gellan gum, locust bean gum, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydrophobic hydroxypropyl methyl cellulose, methyl cellulose, cationic hydroxyethyl cellulose, carboxyvinyl polymers, polyvinyl alcohol, and other water-soluble polymers.

[0121] Specific examples of antioxidants include: tocopherol, tocopheryl acetate, butylated hydroxyanisole, and butylated hydroxytoluene.

[0122] Specific examples of preservatives include: methylparaben, ethylparaben, propylparaben, butylparaben, phenoxyethanol, etc.

[0123] Specific examples of moisturizers include: propylene glycol, hyaluronic acid, sodium hyaluronate, polyethylene glycol, mucopolysaccharides, urea, sorbitol, chondroitin sulfate, pyrrolidone carboxylic acid, sodium lactate, polyaspartic acid, etc.

[0124] Specific examples of pearlescent agents include: ethylene glycol monostearate, ethylene glycol monobehenate, ethylene glycol distearate, and ethylene glycol dibehenate.

[0125] Specific examples of astringents include: zinc oxide, zinc p-phenolsulfonate, aluminum hydroxychloride, allantoin aluminum hydroxychloride, peppermint extract, aloe vera extract, witch hazel extract, rosemary extract, lavender extract, eucalyptus extract, etc.

[0126] Specific examples of skin whitening agents include: arbutin, α-arbutin, ascorbic acid, sodium ascorbate phosphate, magnesium ascorbate phosphate, ascorbate tetraisopalmitate, ascorbic acid fatty acid esters, kojic acid, ellagic acid, tranexamic acid and their derivatives, etc.

[0127] Specific examples of spices include natural spices and synthetic spices.

[0128] Specific examples of natural fragrances include: rose oil, jasmine oil, lavender oil, ylang-ylang oil, peppermint oil, geranium oil, patchouli oil, sandalwood oil, cinnamon oil, lemon oil, sweet orange oil, bergamot oil, etc.

[0129] Specific examples of synthetic fragrances include: limonene, β-caryophyllene, cis-3-hexenol, linalool, farnesol, β-phenylethanol, 2,6-nonadienal, citral, α-hexylcinnamaldehyde, L-carvone, cyclopentadecanone, linalyl acetate, γ-undecyl lactone, nerolidol, L-menthol, etc.

[0130] The content of the additive is not particularly limited. For example, from the viewpoint of imparting a skin feel, spreadability and moisturizing properties to the cosmetic composition, it is preferably 0.1% to 95% by mass, more preferably 0.5% to 50% by mass, and even more preferably 10% to 40% by mass.

[0131] There are no particular limitations on the method for manufacturing cosmetic compositions. For example, a water-soluble component is added to water and mixed to obtain an aqueous solution. Then, a solid component containing low-substituted cellulose ether spherical particles is added to the obtained aqueous solution and mixed to obtain a mixture. Next, an oil is added to the obtained mixture and mixed. Then, the obtained mixture is subjected to additional processing treatments such as drying as needed to obtain a cosmetic composition.

[0132] The cosmetic composition of one aspect of the present invention is not particularly limited in its method of use or dosage form. For example, it can be applied to: color cosmetics, skin care cosmetics, fragrance cosmetics, body care cosmetics, etc. Specifically, it can be applied to: creams, lotions, foundations, toners, serums, sunscreens, face masks, facial cleansers, hand creams, makeup removers, primers, concealers, blushes, eyeshadows, eyeliners, eyebrow pencils, lipsticks, sunscreens, hair removal creams, multi-functional skin care products, etc. Furthermore, the cosmetic composition of one aspect of the present invention can be impregnated into sheets, etc., or sprayed. Therefore, the cosmetic composition of one aspect of the present invention is expected to be formulated into dosage forms such as impregnated sheets, impregnated masks, pumps, and sprays.

[0133] Example

[0134] The present invention will now be specifically described through examples and comparative examples, but the present invention is not limited to the examples described below. Unless otherwise stated, all operations are performed at 25°C.

[0135] The low-substituted degree cellulose ethers (CEs) used as granular low-substituted hydroxypropyl cellulose in the examples and comparative examples are shown in Table 1.

[0136] Table 1

[0137]

[0138] The molar degree of substitution of low-substituted cellulose ethers is calculated by converting the value determined using the quantitative method described in the entry "Low-substituted hydroxypropyl cellulose" in the 18th revised edition of the Japanese Pharmacopoeia.

[0139] The average particle size and aspect ratio of low-substituted cellulose ethers were determined by the methods described in the entries for <Average Particle Size of Primary Particles> and <Aspect Ratio>, which are described later.

[0140] [Example 1]

[0141] <Preparation of alkaline aqueous solutions of low-substituted cellulose ethers>

[0142] 190g of a 5% (w / w) sodium hydroxide aqueous solution was added to a 500ml beaker and cooled to 5°C in a water bath. Then, while stirring the 5% (w / w) sodium hydroxide aqueous solution, 10g of CE-1 (a low-substitution degree cellulose ether) was added and stirred until the CE-1 was uniformly dissolved, thus preparing an alkaline aqueous solution of a 5% (w / w) CE-1 low-substitution degree cellulose ether.

[0143] <Preparation of W / O type low-substitution degree cellulose ether emulsion>

[0144] Add 90 ml of silicone oil KF-96L-1.5cs (manufactured by Shin-Etsu Chemical Co., Ltd.), 10 ml of an alkaline aqueous solution of low-substituted cellulose ether with a content of 5% by mass of CE-1, and 0.1 ml of polyether-modified silicone KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a surfactant to a 500 ml beaker. Then, use a homogenizer ("MARKI I2.5 type homogenizer", manufactured by Primix, rotor diameter 30.0 mm) to stir these raw materials at a speed of 8000 rpm for 15 minutes to prepare a W / O type low-substituted cellulose ether emulsion.

[0145] <W / O type acidic aqueous emulsion>

[0146] Add 90 ml of silicone oil KF-96L-1.5cs (manufactured by Shin-Etsu Chemical Co., Ltd.) to a 500 ml beaker, dissolve sodium chloride in 10 ml of a 10% (w / w) hydrochloric acid aqueous solution to achieve a final sodium chloride concentration of 10% (w / w), and add 0.1 ml of polyether-modified silicone KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a surfactant. Then, using a homogenizer (“MARKII 2.5 type homogenizer”, manufactured by Primix, rotor diameter 30.0 mm), stir these raw materials at 8000 rpm for 15 minutes to prepare a W / O type acidic aqueous solution emulsion.

[0147] <Formation of low-substituted cellulose ether spherical particles>

[0148] Using a homogenizer ("MARKII 2.5 homogenizer", Primix, 30.0 mm rotor diameter), 100 ml of a W / O type acidic aqueous solution emulsion was stirred at 3000 rpm while 100 ml of a W / O type low-substituted cellulose ether emulsion was added over 15 minutes. The resulting mixture was then stirred with a magnetic stirrer at 2000 rpm for 3 hours to precipitate low-substituted cellulose ether spherical particles.

[0149] The suspension containing the low-substituted cellulose ether spherical particles was added to a 300 ml separatory funnel. After standing, the lower aqueous layer containing the low-substituted cellulose ether spherical particles was collected. The aqueous layer was filtered through a Kiriyama funnel equipped with No. 5A filter paper. The filtrate was then washed with water and ethanol, and the ethanol was air-dried from the filtrate to obtain the low-substituted cellulose ether spherical particles (MB-1).

[0150] [Examples 2-5]

[0151] Except for changing the low degree of substitution cellulose ether used from CE-1 to CE-2 to 5, the low degree of substitution cellulose ether spherical particles (MB-2 to 5) were prepared in the same manner as in Example 1.

[0152] [Example 6]

[0153] In the preparation of the W / O type low-substitution degree cellulose ether emulsion, the amount of the alkaline aqueous solution of the low-substitution degree cellulose ether was changed to 20 ml, and the amount of silicone oil KF-96L-1.5cs was changed to 80 ml. In the preparation of the W / O type acidic aqueous solution emulsion, the amount of 10% hydrochloric acid aqueous solution (dissolving 10% sodium chloride) was changed to 20 ml, and the amount of silicone oil KF-96L-1.5cs was changed to 80 ml. Otherwise, the low-substitution degree cellulose ether spherical particles (MB-6) were prepared in the same manner as in Example 1.

[0154] [Example 7]

[0155] In the preparation of the W / O type low-substitution degree cellulose ether emulsion, the amount of the alkaline aqueous solution of the low-substitution degree cellulose ether was changed to 35 ml, and the amount of silicone oil KF-96L-1.5cs was changed to 65 ml. In the preparation of the W / O type acidic aqueous solution emulsion, the amount of 10% hydrochloric acid aqueous solution (dissolving 10% sodium chloride) was changed to 35 ml, and the amount of silicone oil KF-96L-1.5cs was changed to 65 ml. Otherwise, the low-substitution degree cellulose ether spherical particles (MB-7) were prepared in the same manner as in Example 1.

[0156] [Comparative Example 1]

[0157] In the preparation of the W / O type low-substitution degree cellulose ether emulsion, the amount of the alkaline aqueous solution of the low-substitution degree cellulose ether was changed to 45 ml, and the amount of silicone oil KF-96L-1.5cs was changed to 55 ml. In the preparation of the W / O type acidic aqueous solution emulsion, the amount of 10% hydrochloric acid aqueous solution (dissolving 10% sodium chloride) was changed to 45 ml, and the amount of silicone oil KF-96L-1.5cs was changed to 55 ml. Otherwise, the low-substitution degree cellulose ether spherical particles (MB-8) were prepared in the same manner as in Example 1.

[0158] [Comparative Example 2]

[0159] 7.5 g of CE-1 was dissolved in 425 g of a 6.3% (w / w) sodium hydroxide aqueous solution. The resulting solution was sheared and ground at 5000 rpm using an Ace homogenizer (manufactured by Nippon Seiki Co., Ltd.), while simultaneously neutralizing by adding 40.2 g of acetic acid dropwise over 5 minutes through a small orifice in the container. The neutralized solution was then sheared and ground again at 10000 rpm for 10 minutes. The resulting gel was centrifuged at 25°C and 10000 rpm for 10 minutes using a cooling centrifuge (“himac CR22N”, manufactured by Eppendorf Hitachi Koki Technology Co., Ltd.). After centrifugation, the supernatant was discarded, and the resulting precipitate was redispersed in pure water to achieve a solids concentration of 2% (w / w). The dispersion was spray-dried using a spray drying device (“mobile small closed-loop circulation system”, manufactured by GEA Niro Co., Ltd.) via a rotary atomizer to prepare low-substituted cellulose ether spherical microparticles (MB-9). In addition, the operating conditions are: atomizer speed of 28,000 rpm; drying chamber inlet temperature of 120℃; drying chamber outlet temperature of 60℃; and air supply volume of 100 kg / h.

[0160] The compositions of the W / O type low-substituted cellulose ether emulsion and the W / O type acidic aqueous solution emulsion prepared in the examples and comparative examples are shown in Table 2.

[0161] Table 2

[0162]

[0163] [Determination of physical properties of low-substituted cellulose ether spherical microparticles]

[0164] The average particle size, true sphericity, surface smoothness, and aspect ratio of the obtained low-substituted cellulose ether spherical microparticles and spherical microparticles (MB-10) made from commercially available cellulose were determined. The results are shown in Table 3.

[0165] <Average particle size of primary particles>

[0166] The average particle size of primary particles of spherical microparticles, which is the average particle size (D) of primary particles as a volume reference determined by dry laser diffraction. 50 Using a laser diffraction particle size distribution measuring device (“MasterSizer 3000”, manufactured by Malvern Panaco), the diameter of the cumulative particle size distribution curve equivalent to 50% of the volume reference was measured by dry method according to Fraunhofer diffraction theory, under the conditions of dispersion pressure of 1.5 bar and scattering intensity of 2% to 10%.

[0167] True Sphericity

[0168] The true sphericity of spherical particles is calculated by observing images of the particles taken with a scanning electron microscope (2000x) and dividing the equivalent circumference (the circumference of a circle with the same projected area as the particle image) by the circumference (the circumference of the particle's projected image). The measurement is performed on at least 30 particles, repeated at least 10 times, and the average true sphericity of at least 300 spherical particles is calculated.

[0169] <Surface Smoothness>

[0170] The surface smoothness of spherical particles is calculated by observing images of spherical particles taken with a scanning electron microscope (2000x) using the following formula.

[0171] Surface smoothness = (1 - (S1) / (S2)) × 100

[0172] In the above formula, S2 represents the area (projected area) occupied by the spherical particles in the image, and S1 represents the sum of "the area that is outside the outline of the circle with the same projected area as S2 and inside the outline of the spherical particles in the image" and "the area that is inside the outline of the circle with the same projected area as S2 and outside the outline of the spherical particles in the image" when the spherical particles in the image overlap with a circle with the same projected area as S2.

[0173] Furthermore, the method for overlapping the spherical particles in the image with a circle having the same projected area as S2 is as follows. When overlapping the spherical particles in the image with a circle having the same projected area as S2, the overlap is performed in a manner that maximizes the area of ​​the overlapping region of the two images (the area that is inside the outline of the circle having the same projected area as S2 and inside the outline of the spherical particles in the image).

[0174] If the number of particles measured in one measurement is more than 30, repeat the measurement more than 10 times and calculate the average surface smoothness of more than 300 spherical microparticles.

[0175] Aspect Ratio

[0176] The aspect ratio of low-substituted cellulose ether spherical microparticles was determined using a scanning electron microscope ("JSM-6010LA", manufactured by Nippon Electron Co., Ltd.). Fifty randomly selected particles were photographed at a measurable magnification, and the major axis (L) and minor axis (D) of each particle were measured. The aspect ratio (L / D) was calculated from the obtained values, and the average aspect ratio (mean aspect ratio) (n = 50) was calculated from the calculated aspect ratio values.

[0177] Table 3

[0178]

[0179] As shown in Table 3, the average particle size (D) of the primary particles of the low-substituted cellulose ether spherical microparticles MB-1 to MB-7 in Examples 1 to 7, measured using dry laser diffraction, is based on a volume standard. 50 The particle size ranges from 1 μm to 30 μm, the sphericity is 0.75 to 1.0, and the surface smoothness is 75% to 100%. When prepared by emulsion coagulation and precipitation, fine water droplets are generated in the oil by applying mechanical shear to the emulsion. In MB-8 of Comparative Example 1, due to the higher water content relative to oil, it is speculated that the average particle size of the primary particles increases because the generated fine droplets aggregate to form larger droplets, and because they cannot break themselves before becoming fine droplets. Furthermore, it is known that when the manufacturing method is spray drying, as in MB-9 of Comparative Example 2, only low-substituted cellulose ether spherical particles with low sphericity and surface smoothness can be obtained.

[0180] [Examples 8-16, Comparative Examples 3-4, and Reference Example 1]

[0181] <Preparation of Cosmetic Compositions>

[0182] Using spherical microparticles from MB-1 to MB-10, and following the formulations shown in Table 4, cosmetic compositions simulating liquid foundation (Examples 8-16, Comparative Examples 3-4, and Reference Example 1) were prepared using the methods described below. MB-10 also used spherical microparticles made from cellulose.

[0183] Using an Ace homogenizer (manufactured by Nippon Seiki Co., Ltd.), a mixture of propylene glycol, polyoxyethylene sorbitan monostearate, and triethanolamine was stirred at 5000 rpm for 5 minutes. Using an Ace homogenizer, a mixture of low-substituted cellulose ether spherical particles, talc, titanium dioxide, iron oxide red, iron oxide yellow, and iron oxide black was added to the resulting solution at 70°C and stirred for 5 minutes. An oiling agent, consisting of stearic acid, glyceryl stearate, liquid lanolin, and liquid paraffin dissolved by heating at 70°C, was added to the resulting solution. Using an Ace homogenizer, the mixture was stirred at 5000 rpm for 5 minutes at 70°C to obtain a liquid cosmetic composition.

[0184] Table 4

[0185]

[0186] <Sensory Evaluation of Cosmetic Compositions>

[0187] Regarding the obtained cosmetic composition, sensory evaluation was conducted by five reviewers specializing in cosmetic user experience assessment, focusing on its skin feel, spreadability on the skin, and moisturizing properties. Each component was scored out of 5 using the evaluation criteria shown below, and the average score of the five reviewers was calculated. Furthermore, scores of 3.0 or higher for all aspects of skin feel, spreadability on the skin, and moisturizing properties were designated as "+", while scores below 3.0 were designated as "-". The results are shown in Table 5.

[0188] 5: Very good

[0189] 4: Good

[0190] 3: Normal

[0191] 2: Poor

[0192] 1: Very poor

[0193] Table 5

[0194]

[0195] As shown in Table 5, cosmetic compositions prepared using low-substituted cellulose ether spherical microparticles with average particle size, sphericity, and surface smoothness within a specific range of primary particles exhibit excellent skin feel, spreadability on the skin, and moisturizing properties, resulting in a superior user experience.

[0196] In contrast, the cosmetic composition of Comparative Example 3, prepared using low-substituted cellulose ether spherical microparticles with a large average particle size, and the cosmetic composition of Comparative Example 4, prepared using low-substituted cellulose ether spherical microparticles with low sphericity and surface smoothness, are inferior in any of the following aspects: skin feel, spreadability on the skin, and moisturizing properties, resulting in a poor user experience.

[0197] Furthermore, the cosmetic composition in Reference Example 1 was formulated using cellulose spherical microparticles, resulting in a poor user experience. This is presumably because cellulose spherical microparticles have lower water absorption and swelling properties compared to low-substituted cellulose ether spherical microparticles.

[0198] Industrial availability

[0199] The low-substituted cellulose ether spherical microparticles of one embodiment of the present invention can be used as an ingredient in cosmetic compositions to impart an excellent user experience to the cosmetic compositions. The cosmetic compositions of one embodiment of the present invention can be used as color cosmetics, skincare cosmetics, etc.

[0200] Cross-references to related applications

[0201] This application claims priority to Japanese Patent Application No. 2024-078097, filed May 13, 2024, the entire contents of which are hereby incorporated by way of publication. Furthermore, the entire contents of all documents cited in the detailed description of the invention in this application, including Patent Documents 1-3, are hereby incorporated by way of publication.

Claims

1. Low-substituted cellulose ether spherical microparticles, characterized in that, The average particle size (D) of the primary particles was determined using dry laser diffraction as a volume reference. 50 The surface area is 1μm to 30μm, the sphericity is 0.75 to 1.0, and the surface smoothness is 75% to 100%.

2. The low-substitution degree cellulose ether spherical microparticles according to claim 1, characterized in that, The molar degree of substitution of low-substituted cellulose ethers is 0.05 to 1.

0.

3. A cosmetic composition, characterized in that, It comprises low-substituted cellulose ether spherical microparticles and oil as described in claim 1 or 2.

4. The cosmetic composition according to claim 3, characterized in that, It also contains water.

5. The method for manufacturing low-substituted cellulose ether spherical microparticles according to claim 1 or 2, characterized in that, Include: In step (1), the alkaline aqueous solution of the low-substituted cellulose ether as raw material and the non-water-soluble solvent are mixed at a volume ratio of 1:99 to 40:60 to obtain a W / O type low-substituted cellulose ether emulsion. Step (2) involves mixing the acidic aqueous solution and the insoluble solvent as raw materials at a volume ratio of 1:99 to 40:60 to obtain a W / O type acidic aqueous solution emulsion; and In step (3), the W / O type low-substitution degree cellulose ether emulsion is mixed with the W / O type acidic aqueous solution emulsion to obtain the low-substitution degree cellulose ether spherical particles as described in claim 1 or 2.

6. The method for manufacturing low-substituted cellulose ether spherical microparticles according to claim 5, characterized in that, The raw materials of step (1) further include surfactants; and / or, the raw materials of step (2) further include surfactants.

7. The method for manufacturing low-substituted cellulose ether spherical microparticles according to claim 5, characterized in that, The non-water-soluble solvent is independently selected from at least one non-water-soluble solvent chosen from silicone oil and hydrocarbon solvents with 5 to 10 carbon atoms.

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