JP7471049B2 - Cosmetic composition containing biodegradable resin particles - Google Patents

Description

The present invention relates to a cosmetic composition containing biodegradable resin particles.

In recent years, with increasing environmental awareness, there has been a growing trend to replace conventional resins with biodegradable resins, and this trend is also seen in the field of resin particles (for example, Patent Document 1, etc.).
However, since the biodegradable particles of Patent Document 1 are produced by melt-kneading and extruding with other resins, and then dissolving the other resins, the inside of the particles is not made porous and is thought to have a solid structure. Biodegradable particles with a solid structure have a small specific surface area, so they have poor biodegradability efficiency and there is a concern that they will remain in the environment for a long time.

In addition, in Patent Document 2, a hydrophobic biodegradable polymer is dissolved in a hydrophobic organic solvent, apatite powder is added to prepare a raw material solution, the raw material solution is added to an aqueous surfactant solution containing an inorganic salt to emulsify, and dispersed fine particles are collected from this emulsion to produce biodegradable polymer particles. The biodegradable polymer particles obtained by this method have a porous surface, but the inside remains a solid structure. Therefore, once the biodegradation of the surface is completed, the biodegradation efficiency decreases, and there is concern that they will remain in the environment for a long time.

Such biodegradable resin particles are also in demand for cosmetic applications, but from the standpoint of biodegradability, there is room for improvement in the above biodegradable resin particles before they can be used in cosmetic applications.

JP 2003-73233 A JP 2010-126588 A

The object of the present invention is to provide a cosmetic composition containing biodegradable resin particles having a structure with superior biodegradability.

To increase the surface area and biodegradability, it is effective to make the inside porous. However, if the internal pore size is too small, the efficiency of hydrolysis will decrease due to reduced water flow. In addition, depending on the size of the microorganisms or bacteria, it may become difficult for them to penetrate inside. In this situation, the inventors have succeeded in controlling the pores of the biodegradable resin, and have succeeded in forming a suitable number of single pores of a suitable size inside the particles. In light of the shape of the internal pores, etc., such particles are expected to be effective in improving biodegradability.

That is, the present invention is as follows.
[1] A cosmetic composition comprising biodegradable resin particles, characterized in that one or more single holes are observed inside the particles in a cross-sectional photograph taken by a scanning transmission electron microscope, and the number of single holes such that D2/D1 is 0.05 or more and 0.20 or less, where D1 is the sum of the particle's major axis and minor axis and D2 is the sum of the single hole's major axis and minor axis, is 5 or more per particle.
[2] A cosmetic composition comprising the biodegradable resin particles according to [1] above, the volume average particle size of which is 1.0 to 30 μm.
[3] A cosmetic composition comprising the biodegradable resin particles according to [1] or [2], wherein the arithmetic mean value of the sum D2 of the major axis and minor axis of the single pore is 0.1 to 4.5 μm.
[4] A cosmetic composition comprising the biodegradable resin particles according to any one of [1] to [3], wherein the biodegradable resin is a dehydration condensate of an aliphatic dicarboxylic acid and an aliphatic diol, or a dehydration condensate of an aliphatic hydroxycarboxylic acid.

The cosmetic composition of the present invention contains particles that are excellent in biodegradability because an appropriate number of appropriately sized single holes are formed inside the particles. Therefore, according to the present invention, it is possible to provide an environmentally friendly cosmetic composition.

FIG. 1 is a scanning transmission electron microscope photograph of the cross section of the biodegradable microparticles obtained in Synthesis Example 1. FIG. 2 is a scanning transmission electron microscope photograph of the cross section of the biodegradable microparticles obtained in Synthesis Example 2. FIG. 3 is a scanning transmission electron microscope photograph of the cross section of the biodegradable microparticles obtained in Comparative Synthesis Example 1.

1. Biodegradable Resin Particles 1-1. Components As the biodegradable resin to be made into particles in the present invention, various known biodegradable resins can be used, and among them, biodegradable polyester resins such as a dehydration condensation product of an aliphatic dicarboxylic acid and an aliphatic diol, or a dehydration condensation product of an aliphatic hydroxycarboxylic acid, are preferred.

1-1-1. Dehydration condensation product of aliphatic dicarboxylic acid and aliphatic diol (hereinafter referred to as biodegradable resin 1)
Examples of the aliphatic dicarboxylic acid include dicarboxylic acids (particularly α,ω-alkanedicarboxylic acids) having about 2 to 10 carbon atoms, preferably about 3 to 8 carbon atoms, such as oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, and sebacic acid, with succinic acid being the most preferred. These aliphatic dicarboxylic acids may be used alone or in appropriate combination of two or more kinds.

The aliphatic diols include diols (particularly α,ω-alkanediols) having about 2 to 10 carbon atoms, such as ethylene glycol, propylene glycol, and tetramethylene glycol, with ethylene glycol being the most preferred. These aliphatic diols may be used alone or in combination of two or more.

Biodegradable resin 1 may contain components capable of undergoing condensation polymerization with hydroxyl groups or carboxylic acid groups, such as polyether diols, hydroxycarboxylic acids, compounds having a total of three or more hydroxyl groups or carboxylic acid groups, or both, amino acids, and polyamines, as necessary.

Examples of biodegradable resin 1 include polyethylene oxalate, polyethylene succinate, polyethylene adipate, polyethylene azelate, polybutylene oxalate, polybutylene succinate, polybutylene adipate, polybutylene sebacate, polyhexamethylene sebacate, polyneopentyl oxalate, etc., with polyethylene succinate being preferred.

1-1-2. Dehydration condensation product of aliphatic hydroxycarboxylic acid (hereinafter referred to as biodegradable resin 2)
Examples of the hydroxycarboxylic acid include glycolic acid, lactic acid, etc., and the hydroxycarboxylic acid may be a cyclic polymer, for example, glycolide (1,4-dioxane-2,5-dione), dilactide (3,6-dimethyl-1,4-dioxane-2,5-dione), etc. Preferred hydroxycarboxylic acids are lactic acid, dilactide, etc., and more preferred is lactic acid.

The biodegradable resin 2 may also be a ring-opening polymer of lactone, since it has the same structure as a dehydration condensate of hydroxycarboxylic acid. Examples of lactones include lactones with about 3 to 10 carbon atoms, such as β-propiolactone and ε-caprolactone.

The biodegradable resin 2 may contain components capable of undergoing condensation polymerization with hydroxyl groups or carboxylic acid groups, such as aliphatic diols, aliphatic dicarboxylic acids, polyether diols, compounds having a total of three or more hydroxyl groups or carboxylic acid groups, or both, amino acids, and polyamines, as necessary.

The weight average molecular weight of the biodegradable resin is, for example, 10,000 or more, preferably 30,000 or more, and, for example, 300,000 or less, preferably 200,000 or less, more preferably 160,000 or less.

1-2. Morphology The biodegradable resin particles of the present invention have single holes of appropriate size within the particles. These single holes are white areas in scanning transmission electron micrographs, and are displayed as independent holes (discontinuous holes) with identifiable outer edges. In the present invention, the single holes (independent holes) are controlled to an appropriate size and exist in an appropriate number, which is effective in improving biodegradability, improving light scattering properties, and improving drug encapsulation efficiency. Specifically, when the particle size is expressed by the total value D1 (=L+S) of its major axis (L) and minor axis (S), and the single hole (independent hole) size is expressed by the total value D2 (=l+s) of its major axis (l) and minor axis (s), a single hole (independent hole) in which D2/D1 is 0.05 or more and 0.20 or less (hereinafter, sometimes expressed as R _0.05-0.20 . The left side of the subscript indicates the lower limit of D2/D1, and the right side of the subscript indicates the upper limit of D2/D1) is considered to be a single hole (independent hole) of moderate size, and hereinafter, sometimes referred to as a good hole in this specification. The number of good holes is 5 or more, preferably 7 or more, and more preferably 9 or more on average per cross section of a biodegradable resin particle. The more good holes there are, the more effective it is for improving biodegradability, improving light scattering properties, and improving drug encapsulation efficiency. The upper limit of the number of good pores may be equal to the upper limit that is logically set according to the particle size of the biodegradable resin particles, but may be, for example, 20 or less, preferably 18 or less.

The single pores may be more appropriately controlled in the range of D2/D1. For example, the number of second good pores (hereinafter sometimes referred to as R _0.05-0.15 ) in which D2/D1 is 0.05 or more and 0.15 or less per cross section of the biodegradable resin particle is, for example, 6 or more, more preferably 8 or more, and for example, 19 or less, more preferably 17 or less.

In the biodegradable resin particles of the present invention, the single holes (independent holes) are not present on the surface of the particles, but mainly inside the particles, and may even be present near the center of the particles. When the number of good holes is counted focusing on the center, for example, when the number of good holes (R 0.05-0.20 ) whose center is within a circle (referred to as an 80% circle) whose diameter is 0.8×(L+S) and whose center is _the center of the major axis (L) in the cross section of the particle is counted, the number of the good holes (R _0.05-0.20 ) is, for example, about 3 to 12, preferably about 5 to 10, on average. When the number of good holes (R _0.05-0.20 ) whose center is within a circle (50% circle) whose diameter is 0.5×(L+S) is counted, the number of good holes (R _0.05-0.20 ) whose center is within the 50% circle is, for example, about 1 to 5, preferably about 2 to 4, on average.

The volume average particle diameter of the biodegradable resin particles is, for example, 1.0 to 30 μm. By setting the volume average particle diameter within the above range, the size of the single hole can be made appropriate. In addition, since there are many particles with diameters larger than the wavelength of visible light, the particles themselves can have light scattering properties. Furthermore, by setting the volume average particle diameter of the particles to 30 μm or less, the number density of the particles per unit mass can be increased, and the light scattering effect of the particles can also be increased. Furthermore, the volume average particle diameter is preferably 1.5 μm or more, more preferably 2.0 μm or more, and also preferably 20 μm or less, more preferably 10 μm or less.

The arithmetic mean value of the size D2 of the single holes (independent holes) in the particles is, for example, 0.1 to 4.5 μm. By adjusting the size D2 of the single holes so that the arithmetic mean value is within this range, the effects of improving biodegradability, improving light scattering properties, and improving the efficiency of drug encapsulation can be further improved. The arithmetic mean value of D2 is preferably 0.2 μm or more, more preferably 0.3 μm or more, and is preferably 4.0 μm or less, more preferably 3.0 μm or less.

2. Manufacturing Method Biodegradable resin particles having a predetermined number of single pores (good pores) of a predetermined size can be manufactured, for example, by carrying out steps 1 to 4.
Step 1: A biodegradable resin is dissolved in a water-immiscible organic solvent together with a water-soluble polymer that is soluble in a water-immiscible organic solvent (hereinafter referred to as a dual-soluble polymer) (biodegradable resin liquid).
Step 2: Water containing a dispersant (such as a surfactant or a water-soluble polymer that is poorly soluble in a water-immiscible organic solvent) and the biodegradable resin liquid are stirred to prepare a suspension.
Step 3: The water-immiscible organic solvent is evaporated from the suspension to suspend the biodegradable resin particles in the aqueous phase.
Step 4: The aqueous phase and the biodegradable resin particles are separated, and the biodegradable resin particles are washed as necessary and then dried.
The good pores can be controlled by appropriately adjusting the ratio of the bisoluble polymer and dispersant, the suspension strength, etc. according to the type of biodegradable resin.

The water-immiscible organic solvent is a solvent that has the ability to dissolve the biodegradable resin and can form oil droplets in the suspension in step 2, and is useful for forming particles of the biodegradable resin. Examples of the water-immiscible organic solvent include halogenated hydrocarbon solvents such as chloromethane, methylene chloride, chloroform, carbon tetrachloride, and chloroethane; ketone solvents such as 2-pentanone, 3-pentanone, methyl isobutyl ketone, and diisobutyl ketone; and ester solvents such as ethyl acetate and butyl acetate; with halogenated hydrocarbon solvents being preferred.

The amount of the water-immiscible organic solvent is, for example, about 0.5 to 100 parts by mass, preferably about 1 to 60 parts by mass, and more preferably about 3 to 30 parts by mass, per 1 part by mass of the biodegradable resin.

It is presumed that the doubly soluble polymer used in step 1, when present together with water in the oil droplets of the suspension in step 2, introduces water into the oil droplets, which then forms good pores. Examples of doubly soluble polymers that play this role include polyvinylpyrrolidone, polyethylene glycol, methylcellulose, etc., with polyvinylpyrrolidone being preferred.

The K values of both soluble polymers can be set as necessary, for example, to 5 or more, preferably 10 or more, more preferably 15 or more, and for example, to 150 or less, preferably 90 or less, more preferably 50 or less.

The K value is a viscosity characteristic value correlated with molecular weight, and is calculated by applying a relative viscosity value (25° C.) measured by a capillary viscometer to the following Fikentscher formula.
K = (1.5 log _{η rel} -1) / (0.15 + 0.003 c) + (300 c _{log η rel} + (c + 1.5 c _{log η rel} ) ² ) ^1/2 / (0.15 c + 0.003 c2)
[wherein η _rel represents the relative viscosity of the aqueous solution of the dual-soluble polymer to water, and c represents the concentration (%) of the dual-soluble polymer in the aqueous solution of the dual-soluble polymer]
The K value may be determined by using a value measured by the manufacturer instead of actually measuring it.

The amount of the doubly soluble polymer used in step 1 is, for example, about 0.1 to 100 parts by mass, preferably about 1 to 60 parts by mass, and more preferably about 3 to 30 parts by mass, per 100 parts by mass of the biodegradable resin.

The dispersant used in step 2 has the effect of increasing the stability of the oil phase of the suspension, and may be a surfactant or a water-soluble polymer that is poorly soluble in water-immiscible organic solvents. Examples of surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants.

Examples of water-soluble polymers that are poorly soluble in water-immiscible organic solvents include polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, and sodium polyacrylate.

In the suspension preparation stage of step 2, forced stirring is usually performed. The size of the biodegradable resin particles can be adjusted by forced stirring. For the forced stirring, a known emulsification and dispersion device can be used, such as a high-speed shear turbine type disperser such as T. K. Homomixer (manufactured by Primix Corporation (formerly Tokushu Kika Kogyo)); a high-pressure jet homogenizer such as a piston-type high-pressure homogenizer (manufactured by Gaulin Co., Ltd.) or a Microfluidizer (manufactured by Microfluidics Co., Ltd.); an ultrasonic emulsification and dispersion device such as an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.); a medium stirring type disperser such as an attritor (manufactured by Mitsui Mining Co., Ltd.); a forced gap passing type disperser such as a colloid mill (manufactured by Nippon Seiki Seisakusho Co., Ltd.). For continuous production, an Ebara Milder (manufactured by Ebara Corporation) can be used. Note that prior to the above forced stirring, preliminary stirring may be performed using a normal paddle blade or the like.

The stirring speed affects the particle size of the oil droplets in the suspension, and the faster the stirring speed, the smaller the particle size of the biodegradable resin particles. For example, when stirring in a 1-liter container using the above-mentioned T. K. Homomixer (suspended type), a range of approximately 5,000 rpm to 15,000 rpm is preferable. The stirring time also affects the particle size of the oil droplets, and can be set appropriately depending on the desired particle size.

By evaporating and distilling off the organic solvent from the suspension in step 3, it is believed that the biodegradable resin particles can be dispersed in the aqueous phase, and the bisoluble polymer is left behind within the biodegradable resin particles. It is presumed that the bisoluble polymer embraces water, forming fine water bubbles within the biodegradable resin particles, which then transform into good pores. When evaporating the organic solvent, the suspension is heated to a temperature equal to or higher than the boiling point of the organic solvent. If necessary, the suspension may be heated or the boiling point may be lowered by reducing the pressure. However, it is preferable that the temperature be controlled to be equal to or lower than the boiling point of water.

The absolute pressure during the reduced pressure is, for example, 1 to 300 Torr, preferably 5 to 200 Torr, and more preferably 10 to 100 Torr. The temperature during the solvent distillation can be, for example, 5 to 80°C, preferably 20 to 70°C, and more preferably about 30 to 60°C.

After the organic solvent is distilled off, the biodegradable resin particles are separated from the aqueous phase. For this separation, a conventional solid-liquid separation means such as centrifugation or filtration can be appropriately used. The separated biodegradable resin particles may be washed with water, a water-soluble organic solvent, or the like, as necessary. By performing such washing, the amount of dispersant in the biodegradable resin particles can be reduced. Examples of water-soluble organic solvents include alcohols such as methanol, ethanol, and propanol; cyclic ethers such as THF and dioxane; ether-based polyols such as dimethoxyethane and diethylene glycol; ketones such as acetone; and amides such as dimethylformamide and dimethylacetamide. Preferred water-soluble organic solvents are alcohols.

There are no particular limitations on the drying conditions for the separated biodegradable resin particles, but drying at a low temperature is preferred to prevent adhesion between the particles, and reduced pressure drying (particularly vacuum drying) is preferred for this purpose.

3. Cosmetic Composition The cosmetic composition of the present invention contains the above-mentioned biodegradable resin particles. The above-mentioned biodegradable resin particles have excellent biodegradability and can therefore be suitably used in cosmetic compositions.

The content of the biodegradable resin particles in the cosmetic composition is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of being able to exhibit sufficient biodegradability when made into a composition. Also, from the viewpoint of ensuring cosmetic performance other than biodegradability, the content is preferably 50% by mass or less.

The cosmetic of the present invention can be appropriately blended with ingredients that are usually blended in cosmetics, such as oily ingredients, powdery ingredients, surfactants, oil gelling agents, aqueous ingredients, water-soluble polymers, UV absorbers, antioxidants, beauty ingredients, preservatives, etc., to impart various effects.

Oily ingredients include hydrocarbons, fats and oils, waxes, ester oils, hardened oils, fatty acids, higher alcohols, silicone oils, lanolin derivatives, oil-based gelling agents, etc., regardless of their origin (animal oil, vegetable oil, synthetic oil, etc.) and their nature (solid, semi-solid oil, liquid oil, volatile oil, etc.). Specific examples of the wax include hydrocarbons such as paraffin wax, ceresin wax, microcrystalline wax, montan wax, Fischer-Tropsch wax, liquid paraffin, squalane, and petrolatum; oils and fats such as Japan wax, mink oil, olive oil, avocado oil, castor oil, and macadamia nut oil; waxes such as beeswax, carnauba wax, candelilla wax, and glaber wax; pentaerythritol ester of rosin acid, jojoba oil, glyceryl tri-2-ethylhexanoate, isotridecyl isononanoate, cetyl 2-ethylhexanoate, isopropyl myristate, isopropyl palmitate, octyldodecyl myristate, glyceryl trioctanoate, polyglyceryl diisostearate, glyceryl triisostearate, diglyceryl triisostearate, polyglyceryl triisostearate, diisostearyl malate, and neopentyl diethylhexanoate. fatty acids such as oleic acid, isostearic acid, stearic acid, lauric acid, myristic acid, behenic acid, etc.; higher alcohols such as stearyl alcohol, cetyl alcohol, lauryl alcohol, behenyl alcohol, etc.; silicone oils such as methylpolysiloxane, methylphenylpolysiloxane, trimethylsiloxysilicic acid, crosslinked polyether-modified methylpolysiloxane, methacryl-modified methylpolysiloxane, oleyl-modified methylpolysiloxane, polyvinylpyrrolidone-modified methylpolysiloxane, polyether-modified polysiloxane, etc.; lanolin derivatives such as lanolin, lanolin acetate, lanolin fatty acid isopropyl, lanolin alcohol, etc.; oil-based gelling agents such as aluminum isostearate, calcium stearate, 12-hydroxystearic acid, etc., and these may be used alone or in combination. Among these, low molecular weight ester oils such as glyceryl tri-2-ethylhexanoate, isononyl isononanoate, and neopentyl glycol diethylhexanoate are preferred from the standpoint of spreadability and adhesion.

The powder components are not particularly limited by shape (e.g., spherical, plate-like, needle-like, etc.), particle size (e.g., aerosol, fine particles, pigment-grade, etc.), particle structure (e.g., porous, non-porous, etc.), and include inorganic powders, glittering powders, organic powders, pigment powders, metal powders, composite powders, etc. Specific examples include white inorganic pigments such as titanium oxide, zinc oxide, cerium oxide, barium sulfate, etc.; colored inorganic pigments such as iron oxide, carbon black, chromium oxide, chromium hydroxide, iron blue, ultramarine, etc.; talc, muscovite, phlogopite, red mica, black mica, synthetic mica, sericite, synthetic sericite, kaolin, silicon carbide, bentonite, smectite, aluminum oxide, magnesium oxide, zirconium oxide, antimony oxide, diatomaceous earth, aluminum silicate, magnesium aluminum metasilicate, calcium silicate, barium silicate, magnesium silicate, white body powders such as ammonium, calcium carbonate, magnesium carbonate, hydroxyapatite, boron nitride, and silica; luster powders such as titanium dioxide-coated mica, titanium dioxide-coated bismuth oxychloride, iron oxide-coated mica titanium, iron oxide mica, Prussian blue-treated mica titanium, carmine-treated mica titanium, bismuth oxychloride, and fish scale foil; polyamide resins, polyethylene resins, polyacrylic resins, polyester resins, fluorine-based resins, cellulose resins, polystyrene resins, copolymer resins such as styrene-acrylic copolymers, polypropylene resins, silicone resins, etc. organic polymer resin powders such as corn resin and urethane resin; organic low molecular weight powders such as zinc stearate and N-acyl lysine; natural organic powders such as starch, silk powder and cellulose powder; organic pigment powders such as Red No. 201, Red No. 202, Red No. 205, Red No. 226, Red No. 228, Orange No. 203, Orange No. 204, Blue No. 404 and Yellow No. 401; organic pigment powders such as Red No. 3, Red No. 104, Red No. 106, Orange No. 205, Yellow No. 4, Yellow No. 5, Green No. 3 and Blue No. 1, such as zirconium, barium or aluminum lake, or further aluminum powder; Examples of the powder include metal powders such as gold powder and silver powder, composite powders such as titanium oxide-coated mica titanium, zinc oxide-coated mica titanium, barium sulfate-coated mica titanium, titanium oxide silicon dioxide, and zinc oxide silicon dioxide, glittering agents such as polyethylene terephthalate-aluminum-epoxy laminate powder, polyethylene terephthalate-polyolefin laminate film powder, and polyethylene terephthalate-polymethyl methacrylate laminate film powder, tar dyes, and natural dyes. These powders can be used alone or in combination, or in combination. These powder components may be surface-treated with one or more of fluorine-based compounds, silicone-based compounds, metal soaps, lecithin, hydrogenated lecithin, collagen, hydrocarbons, higher fatty acids, higher alcohols, esters, wax quartz, wax, and surfactants.

Surfactants include non-ionic surfactants such as glycerin fatty acid esters and their alkylene glycol adducts, polyglycerin fatty acid esters and their alkylene glycol adducts, propylene glycol fatty acid esters and their alkylene glycol adducts, sorbitan fatty acid esters and their alkylene glycol adducts, sorbitol fatty acid esters and their alkylene glycol adducts, polyalkylene glycol fatty acid esters, polyoxyalkylene-modified silicones, and polyoxyalkylene alkyl-co-modified silicones, alkylbenzene sulfates, alkyl sulfonates, α-olefin sulfonates, dialkyl sulfosuccinates, α -Anionic surfactants such as sulfonated fatty acid salts, acyl methyl taurine salts, N-methyl-N-alkyl taurine salts, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, and polyoxyethylene alkyl phenyl ether phosphates; cationic surfactants such as alkyl amine salts, polyamine and alkanoyl amine fatty acid derivatives, alkyl ammonium salts, and alicyclic ammonium salts; amphoteric surfactants such as lecithin and N,N-dimethyl-N-alkyl-N-carboxymethyl ammonium betaine; and the like; and the like, and one or more of these may be used.

Examples of oil gelling agents include dextrin fatty acid esters, sucrose fatty acid esters, starch fatty acid esters, hydroxystearic acid, calcium stearate, hydrophobic fumed silica, and organically modified bentonite, and these may be used alone or in combination of two or more.

Aqueous components may be water or any water-soluble component, and examples of such components include glycols such as propylene glycol, 1,3-butylene glycol, dipropylene glycol, and polyethylene glycol, glycerols such as glycerin, diglycerin, and polyglycerin, and plant extracts such as aloe vera, witch hazel, hamamelis, cucumber, lemon, lavender, and rose.

Examples of water-soluble polymers include natural polymers such as guar gum, sodium chondroitin sulfate, hyaluronic acid, gum arabic, sodium alginate, carrageenan, mucopolysaccharides, collagen, elastin, and keratin; semi-synthetic polymers such as methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose; and synthetic polymers such as carboxyvinyl polymer, polyvinyl alcohol, polyvinylpyrrolidone, and sodium polyacrylate.

Examples of UV absorbers include benzophenones, PABAs, cinnamic acids, salicylic acids, 4-tert-butyl-4'-methoxydibenzoylmethane, and oxybenzone.

Examples of antioxidants include α-tocopherol and ascorbic acid.

Examples of beauty ingredients include vitamins, proteins, anti-inflammatory agents, herbal medicines, etc.

Preservatives include, for example, paraoxybenzoic acid esters, phenoxyethanol, etc.

Other ingredients besides those mentioned above may also be included within the scope of the present invention, such as moisturizers, film-forming agents, anti-fading agents, defoamers, fragrances, fluorine-based oils such as perfluoropolyether, perfluorodecalin, and perfluorooctane; polyhydric alcohols, sugars, amino acids, various polymers, ethanol, thickeners, pH adjusters, blood circulation promoters, cooling agents, bactericides, and skin activators, as long as they do not impair the effects of the present invention.

The cosmetic of the present invention is not particularly limited in its formulation or product form, and can be in the form of water-in-oil, oil-in-water, water-dispersed, pressed, solid, powder, etc., and examples of product forms include skin cosmetics such as facial cleansing foam/cream, cleansing, massage cream, pack, lotion, milky lotion, cream, beauty essence, makeup base, sunscreen, etc.; finishing cosmetics such as foundation, water face powder, eye shadow, eye liner, mascara, eyebrow, concealer, lipstick, lip balm, etc.; hair cosmetics such as hair mists, shampoos, rinses, treatments, hair tonics, hair creams, pomades, tics, liquid hair styling products, setting lotions, hair sprays, hair dyes, etc.; antiperspirants such as powder sprays and roll-ons. Among these, solid preparations such as foundations and face powders are cosmetics that are likely to exhibit the effects of the present invention.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples, and it is of course possible to carry out the invention with appropriate modifications within the scope of the above and below-mentioned aims, all of which are included in the technical scope of the present invention. Note that, although the following examples are shown, the amounts of each component are all given in mass %.

[Physical property measurement method]
Various physical properties were measured by the following methods.

<Number of good holes (R _0.05-0.20 )>
The cross section of the biodegradable resin particles was photographed by a scanning transmission electron microscope under conditions of a magnification of 10,000 to 30,000 times and an acceleration voltage of 20 kV. The photographed image was used to calculate the long diameter (L) and short diameter (S) of the particle cross section and their total D1 (D1 = L + S) (particle size), and the long diameter (l) and short diameter (s) of the single hole of the particle cross section and their total value D2 (single hole size), using a caliper diameter calculation tool attached to the device, and the number of good holes (R _0.05-0.20 ) where D2/D1 was 0.05 or more and 0.20 was determined. For one type of biodegradable polyester particle, the good holes (R _0.05-0.20 ) were determined for 20 particles, and the arithmetic average value was taken as the number of good holes (R 0.05-0.20) in the biodegradable resin particles.

<Number of second good holes (R _0.05-0.15 )>
The number of second good pores (R _0.05-0.15 ) in the particle cross section was determined in the same manner as for the number of good pores (R _0.05-0.15 ) except that D2/D1 was in the range of 0.05 to 0.15.

<Number of good holes (R _0.05-0.20 ) within the 80% circle>
In the same manner as in the number of <good pores (R _0.05-0.20 )>, the particle size D1 and the single pore size D2 were determined, the good pores (R _0.05-0.20 ) were specified, and the number of good pores (R _0.05-0.20 ) having a center of gravity within a circle (80% circle) of diameter 0.8 × (L + S) centered at the center of the particle major axis was determined. For one type of biodegradable polyester particle, R _0.05-0.20 was determined for 20 particles, and the arithmetic average value was regarded as the number of good pores within the 80% circle in the biodegradable resin particle.

<Number of good holes (R _0.05-0.20 ) within the 50% circle>
The number of good pores (R _{0.05-0.20 ) within an 80% circle was determined in the same manner as described above, except that the number of good pores (R 0.05-0.20 )} having a center of gravity within a circle (50% circle) of diameter 0.5 × (L + S) centered at the center of the particle major axis was counted.

<Single hole size>
The D2 values measured for all the single pores contained in the 20 particles measured in the above <Number of good pores (R _0.05-0.20 )> were statistically processed to determine the arithmetic average value, which was taken as the single pore size.

<Volume average particle size and its coefficient of variation (CV value)>
20 parts by mass of a 1% aqueous solution of polyoxyethylene alkyl ether sulfate ester ammonium salt (Hitenol (registered trademark) N-08, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), which is an emulsifier, was added to 0.1 parts by mass of resin particles, and dispersed by ultrasonic waves for 10 minutes to obtain a measurement sample. The particle diameters (μm) of 30,000 particles were measured using a particle size distribution measuring device (Coulter Multisizer III, manufactured by Beckman Coulter, Inc.) to obtain the volume average particle diameter. The standard deviation of the particle diameters on a volume basis was also obtained, and the coefficient of variation (CV value) of the particle diameters was calculated according to the following formula.
Coefficient of variation of particle size (%)=100×(standard deviation of particle size/volume average particle size).

[Production Example 1] Production of polyethylene succinate 0.5 mol of succinic anhydride and 0.52 mol of ethylene glycol were charged into a 300 mL glass reactor equipped with a stirrer, and the water generated was distilled off at 140°C under stirring to carry out a condensation reaction. 3 hours after the start of the reaction, 0.02 g of titanium tetrabutoxide was added as a reaction catalyst, and the reaction temperature was changed to 160°C 5 hours after the start of the reaction, 180°C 8 hours after the start of the reaction, and 200°C 9 hours after the start of the reaction, and the reaction was terminated 12 hours later. 5 hours after the start of the reaction, a vacuum pump was connected, and the pressure was reduced thereafter. The molecular weight in terms of polystyrene was determined by GPC measurement of the chloroform solution (conditions are as follows), and the number average molecular weight Mn was 29,000 and the weight average molecular weight Mw was 63,000.

[Production Example 2] Production of polybutylene succinate/adipate 0.72 mol of succinic anhydride, 0.08 mol of adipic acid, and 0.81 mol of 1,4-butanediol were charged into a 300 mL glass reactor equipped with a stirrer, and the water generated was distilled off at 180°C while stirring to carry out a condensation reaction. 3 hours after the start of the reaction, 0.05 g of titanium tetrabutoxide was added as a reaction catalyst, and 10 hours later, 2.0 g of hexamethylene diisocyanate was added as a terminal binder. The reaction temperature was changed to 200°C 1 hour after the start of the reaction, and to 220°C 2 hours later, and the reaction was completed 12 hours later. 5 hours after the start of the reaction, a vacuum pump was connected, and the pressure was reduced thereafter. The molecular weight in terms of polystyrene was determined by GPC measurement of the chloroform solution (conditions are as follows), and the number average molecular weight Mn was 57,000 and the weight average molecular weight Mw was 128,000.

<GPC measurement conditions>
Measurement system: Tosoh Corporation "GPC system HLC-8220"
Developing solvent: Chloroform (Wako Pure Chemical Industries, Ltd., special grade)
Solvent flow rate: 0.6 mL/min. Standard sample: TSK standard polystyrene ("PS-Oligomer Kit" manufactured by Tosoh Corporation)
Measurement column configuration: guard column ("TSK guard column Super HZ-L" manufactured by Tosoh Corporation), separation column ("TSK Gel Super HZM-M" manufactured by Tosoh Corporation), two columns connected in series. Reference column configuration: reference column ("TSK Gel Super H-RC" manufactured by Tosoh Corporation).

Synthesis Example 1
5.0 g of the polyethylene succinate obtained in Production Example 1 and 0.63 g of polyvinylpyrrolidone (manufactured by Nippon Shokubai Co., Ltd., trade name "Polyvinylpyrrolidone K-30") were added to 45.0 g of methylene chloride and dissolved with stirring. This solution was added to 200 g of an excess of 1% by mass polyvinyl alcohol aqueous solution with stirring to prepare a primary suspension. The primary suspension was stirred at 8000 rpm for 7 minutes with a T. K. Homogenizer (manufactured by Primix Corporation (formerly Tokushu Kika Kogyo Co., Ltd.)) to prepare a secondary suspension. The secondary suspension was transferred to a flask, and the rotary evaporator was driven to rotate the flask at a speed of 100 rpm under reduced pressure conditions of a temperature of 40 ° C. and a pressure of 30 torr to remove methylene chloride. The dispersion was filtered under reduced pressure and washed with methanol. The filtrate was vacuum dried to obtain biodegradable resin particles.

Synthesis Example 2
The same procedure was carried out as in Synthesis Example 1, except that 5.0 g of polyethylene succinate was changed to 5.0 g of polylactic acid (manufactured by Mitsui Chemicals, Inc., product name "LACIA H440").

Synthesis Example 3
The same procedure as in Synthesis Example 1 was repeated, except that 5.0 g of polyethylene succinate was changed to 5.0 g of polybutylene succinate/adipate obtained in Production Example 2.

Comparative Synthesis Example 1
The same procedure as in Synthesis Example 1 was repeated, except that 0.63 g of polyvinylpyrrolidone was not used.

The resin particles obtained in each Example and Comparative Example were photographed with a scanning transmission electron microscope and various characteristics were examined. The scanning transmission electron microscope photographs are shown in Figure 1 (Synthesis Example 1), Figure 2 (Synthesis Example 2), and Figure 3 (Comparative Synthesis Example 1), and the various properties obtained are shown in Table 1.

〔Example〕
In the basic formulation described below, the biodegradable resin particles of Synthesis Examples 1 and 2 and Comparative Synthesis Example 1 shown in Table 1 were used to produce foundations by the manufacturing methods described below, and the cosmetic finish feel, feel in use, and durability were evaluated by the evaluation methods described below.

(Basic recipe)
(1) Methicone-treated talc 18.00% by mass
(2) Methicone-treated titanium dioxide 12.00% by mass
(3) Methicone-treated sericite 43.00% by mass
(4) Biodegradable resin particles 8.00% by mass
(5) Methicone-silica treated titanium dioxide fine particle 5.00% by mass
(6) 0.50% by mass of red iron oxide
(7) Yellow iron oxide 1.00 mass%
(8) Black iron oxide 0.10 mass%
(9) Dimethylpolysiloxane 6.00% by mass
(10) Isotridecyl isononanoate 3.00% by mass
(11) Squalane 3.00% by mass
(12) Preservative: 0.30% by mass
(13) Antioxidant: 0.10% by mass
(Production method)
The powder components (1) to (8) shown in the basic recipe above are mixed and ground, then transferred to a mixer. In a separate container, oil phase components (9) to (13) are mixed. While stirring the mixer, the oil phase components are added and stirred until homogeneous, then ground. This is then press molded into an aluminum dish to obtain the product.

(evaluation)
The obtained foundation was used by a panelist in a normal manner and evaluated for makeup finish, usability, and durability. The foundation was found to be excellent in all performances. Furthermore, the foundation of the present invention not only gave a natural finish, but also a three-dimensional effect and clear shadows, demonstrating excellent performance.

Claims (3)

A cosmetic composition comprising biodegradable resin particles, characterized in that one or more single holes are observed inside the particles in a cross-sectional photograph taken by a scanning transmission electron microscope, the number of single holes having a D2/D1 ratio of 0.05 or more and 0.20 or less, where D1 is the sum of the particle's major axis and minor axis and D2 is the sum of the single hole's major axis and minor axis, is 5 or more per particle , and the volume average particle diameter is 1.0 to 30 μm, and the biodegradable resin is a dehydration condensation product of an aliphatic dicarboxylic acid and an aliphatic diol . A cosmetic composition comprising the biodegradable resin particles according to claim 1, in which the arithmetic mean value D2 of the sum of the major and minor diameters of the single holes is 0.1 to 4.5 μm. A method for producing biodegradable resin particles for use in cosmetics, characterized in that one or more single holes are observed inside the particles in a cross-sectional photograph taken by a scanning transmission electron microscope, and when the sum of the particle's major axis and minor axis is D1 and the sum of the single hole's major axis and minor axis is D2, the number of single holes such that D2/D1 is 0.05 or more and 0.20 or less per particle is 5 or more, the method comprising: a step 1 of dissolving a biodegradable resin in a water-immiscible organic solvent together with a water-soluble polymer that is soluble in a water-immiscible organic solvent; and a step 2 of stirring water containing a dispersant and the biodegradable resin liquid to prepare a suspension, wherein the water-soluble polymer that is soluble in a water-immiscible organic solvent is polyvinylpyrrolidone.

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