JP7289962B2 - Cellulose derivative particles, cosmetic composition, and method for producing cellulose derivative particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cellulose derivative particle, a cosmetic composition, and a method for producing a cellulose derivative particle.

Conventionally, various polymer microparticles have been proposed according to their uses. For example, fine particles contained in cosmetics have various purposes. The purpose of containing fine particles in cosmetics is to improve the spreadability of cosmetics, to change the feel of the cosmetics, to impart wrinkle blurring effects, and to improve the slipperiness of foundations and the like.

In particular, fine particles with a high degree of sphericity are excellent in tactile sensation, and can provide a light scattering (soft focus) effect depending on their physical properties and shape. When such fine particles are used in foundations and the like, it can be expected to have the effect of smoothing the unevenness of the skin and scattering light in various directions to make wrinkles less noticeable (soft focus).

For the purposes and effects of such cosmetics, fine particles to be blended in cosmetics are required to have a narrow particle size distribution and a high degree of sphericity. Microparticles made of synthetic polymers such as methyl methacrylate (PMMA), polystyrene (PS), polypropylene (PP), and polyethylene (PE) have been proposed.

However, among these synthetic polymers, fine particles made of PP, PE, etc., have a specific gravity of 1 or less and a particle size that is too small. It can flow into the sea through rivers and even rivers. As a result, there is a problem that the ocean or the like is polluted with fine particles made of these synthetic polymers. Furthermore, among synthetic polymers, fine particles made of PS contain a phthalate plasticizer such as dioctyl phthalate as a main plasticizer. Some phthalate-based plasticizers are suspected to be endocrine disruptors, and it is not desirable for them to flow into the ocean.

In addition, microparticles made from these synthetic polymers have the property of adsorbing minute amounts of chemical pollutants in the environment, so when plankton and fish swallow the microparticles that have adsorbed the chemical pollutants, they can have a negative impact on the human body. It is feared that it will have various impacts, such as the possibility that it will occur.

Due to such concerns, attempts have been made to replace fine particles of synthetic polymers used in various applications with other particles.

Cellulose or cellulose derivatives are superior in that they can be obtained from natural materials such as wood and cotton, which do not compete with food or feed. For this reason, it would be beneficial to be able to replace microparticles of synthetic polymers with microparticles of cellulose, a natural polymer, or cellulose derivatives, a semi-synthetic polymer. However, the polymer to which the method for producing fine particles of synthetic polymers can be applied is limited, and it is difficult to apply it to the production of fine particles of cellulose or cellulose derivatives.

US Pat. No. 5,300,000 discloses a process for forming a polysaccharide ester product from polysaccharide synthesis, said polysaccharide ester product comprising a polysaccharide ester and a solvent; diluting said polysaccharide ester product, thereby forming a polysaccharide ester dope. and forming a plurality of polysaccharide ester microspheres from said polysaccharide ester dope, wherein cosmetic compositions are cited as articles that may contain the polysaccharide ester microspheres.

In Patent Document 2, the volume average particle diameter D50 measured using a laser diffraction particle size distribution analyzer is 72 μm or more and 100 μm or less, the degree of polymerization is 131 or more and 350 or less, and the degree of substitution is 2.1 or more and 2 A cellulose acylate having a molecular weight of .6 or less, and a method for producing the same, comprising: an acylation step of acylating cellulose in the presence of sulfuric acid; and a deacylation step of deacylating the cellulose acylate.

In Patent Document 3, a resin component (A) such as a thermoplastic resin and a water-soluble auxiliary agent component (B) are kneaded to prepare a dispersion, and the auxiliary agent component (B) is eluted from the dispersion. , the production of a molded body (for example, a porous body, spherical particles) composed of a resin component (A), and a cellulose derivative such as cellulose acetate as the resin component (A).

Japanese Patent Publication No. 2016-500129 Japanese Patent No. 6187653 JP 2004-051942 A

However, the polysaccharide ester microspheres of Patent Document 1 are porous particles with a large particle size and a broad particle size distribution, and are not sufficient as a substitute for fine particles of synthetic polymers blended in cosmetics and the like. The cellulose acylate obtained by the production method described in Patent Document 2 is also amorphous and porous particles. Furthermore, the particulate compact obtained by the manufacturing method described in Patent Document 3 is also particles with a low degree of sphericity and a substantially spherical shape. Therefore, conventional fine particles are inferior in tactile sensation.

An object of the present invention is to provide fine particles containing a semi-synthetic polymer of a cellulose derivative and having excellent tactile sensation.

A first aspect of the present invention is cellulose derivative particles having an alkoxy group having 2 or more carbon atoms or an acyl group having 3 or more carbon atoms, wherein the cellulose derivative particles have an average particle size of 80 nm or more and 100 μm or less, and The present invention relates to cellulose derivative particles having a sphericity of 70% or more and 100% or less, a surface smoothness of 80% or more and 100% or less, and a total degree of substitution of the cellulose derivative of 0.7 or more and 3 or less.

In the cellulose derivative particles, the total degree of substitution of the cellulose derivative may be 2.0 or more and less than 2.6.

In the cellulose derivative particles, the acyl group may have 3 or more and 18 or less carbon atoms.

In the cellulose derivative particles, the alkoxy group may have 2 or more and 8 or less carbon atoms.

The cellulose derivative particles may have a true specific gravity of 1.04 or more.

In the cellulose derivative particles, the cellulose derivative particles may contain a plasticizer, and the content of the plasticizer may be more than 0% by weight and 40% by weight or less relative to the weight of the cellulose derivative particles.

In the cellulose derivative particles, the plasticizer may be a glycerin ester plasticizer.

A second aspect of the present invention relates to cosmetic compositions containing cellulose derivative particles.

In the third aspect of the present invention, a cellulose derivative having a total degree of substitution of 0.7 or more and 3 or less and a water-soluble polymer are kneaded at 200° C. or more and 280° C. or less to obtain a dispersion containing the cellulose derivative as a dispersoid. and a method for producing cellulose derivative particles, comprising a step of removing the water-soluble polymer from the dispersion.

In the method for producing cellulose derivative particles, the cellulose derivative having a total substitution degree of 0.7 or more and 3 or less is a cellulose derivative impregnated with a plasticizer, and the cellulose derivative impregnated with the plasticizer has the total substitution degree of A cellulose derivative of 0.7 or more and 3 or less and the plasticizer may be melt-kneaded in the range of 20°C or more and less than 200°C.

In the method for producing cellulose derivative particles, the plasticizer may be a glycerin ester plasticizer.

In the method for producing cellulose derivative particles, the plasticizer may be triacetin.

In the method for producing cellulose derivative particles, the water-soluble polymer may be polyvinyl alcohol or thermoplastic starch.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide fine particles containing a semi-synthetic polymer of a cellulose derivative and having excellent tactile sensation.

It is drawing explaining the evaluation method of surface smoothness (%). It is drawing explaining the evaluation method of surface smoothness (%).

[Cellulose derivative particles]
The cellulose derivative particles of the present disclosure are cellulose derivative particles having an alkoxy group having 2 or more carbon atoms or an acyl group having 3 or more carbon atoms, and the cellulose derivative particles have an average particle diameter of 80 nm or more and 100 μm or less. and a sphericity of 70% or more and 100% or less, a surface smoothness of 80% or more and 100% or less, and a total substitution degree of the cellulose derivative of 0.7 or more and 3 or less.

A case where the cellulose derivative particles have an alkoxy group with 2 or more carbon atoms will be described. The number of carbon atoms in the alkoxy group is not particularly limited as long as it is 2 or more, but may be 3 or more, or may be 5 or more. Moreover, it may be 20 or less, preferably 8 or less.

Moreover, the cellulose derivative particles may have both an alkoxy group having two or more carbon atoms and an alkoxy group having one carbon number (methoxy group).

Examples of alkoxy groups having 2 or more carbon atoms include ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, and octoxy groups.

A case where the cellulose derivative particles have an acyl group with 3 or more carbon atoms will be described. The number of carbon atoms in the acyl group is not particularly limited as long as it is 3 or more, but may be 4 or more, 10 or more, or 14 or more. Moreover, it may be 40 or less, preferably 18 or less. As the number of carbon atoms in the acyl group increases, the flexibility of the cellulose derivative particles increases.

Moreover, the cellulose derivative particles may have both an acyl group having 3 or more carbon atoms and an acyl group having 2 carbon atoms (acetyl group).

Examples of acyl groups having 3 or more carbon atoms include propionyl, butyryl, pentanoyl (valeryl), hexanoyl, heptanoyl, octanoyl, nonanoyl, undecanoyl, dodecanoyl, tridecanoyl, and tetradecanyl. Noyl (myristoyl) group, pentadecanoyl group, hexadecanoyl group, heptadecanoyl group, octadecanoyl (stearoyl) group and the like.

Where the average particle diameter of the cellulose derivative particles of the present disclosure is 80 nm or more and 100 μm or less, the average particle diameter may be 100 nm or more, 1 μm or more, 2 μm or more, or 4 μm or more. It's okay. Further, it may be 80 μm or less, 40 μm or less, 20 μm or less, or 14 μm or less. If the average particle size is too large, the tactile sensation is poor and the light scattering (soft focus) effect is reduced. On the other hand, if the average particle size is too small, production becomes difficult. The tactile sensation includes not only the tactile sensation when the cellulose derivative particles are directly touched, but also the tactile sensation when the cellulose derivative particles are blended in a cosmetic composition.

The average particle size can be measured using a dynamic light scattering method. Specifically, it is as follows. First, a sample is prepared by making a pure water suspension of cellulose derivative particles with a concentration of 100 ppm using an ultrasonic vibration device. After that, by the laser diffraction method (Horiba Ltd. "Laser diffraction/scattering particle size distribution analyzer LA-960", ultrasonic treatment for 15 minutes, refractive index (1.500, medium (water; 1.333)), The average particle size can be measured by measuring the volume frequency particle size distribution.The average particle size here means the value of the particle size corresponding to the cumulative scattering intensity of 50% in this particle size distribution. say.

The particle size variation coefficient of the cellulose derivative particles of the present disclosure may be 0% or more and 60% or less, and may be 2% or more and 50% or less.

The particle size variation coefficient (%) can be calculated by (standard deviation of particle size/average particle size×100).

The sphericity of the cellulose derivative particles of the present disclosure is 70% or more and 100% or less, preferably 80% or more and 100% or less, more preferably 90% or more and 100% or less, and even more preferably 95% or more and 100% or less. . If it is less than 70%, the tactile feel is poor, and for example, even when blended in a cosmetic composition, the tactile feel and soft focus effect are reduced.

The sphericity can be measured by the following method. Using the image of the particles observed with a scanning electron microscope (SEM), the major axis and minor axis of 30 randomly selected particles are measured, the minor axis/major axis ratio of each particle is obtained, and the minor axis/major axis is obtained. Let the average value of the ratios be the sphericity (%). It should be noted that the closer the sphericity is to 100%, the more sphericity can be determined.

The surface smoothness of the cellulose derivative particles of the present disclosure is 80% or more and 100% or less, preferably 85% or more and 100% or less, and more preferably 90% or more and 100% or less. If it is less than 80%, the tactile sensation is poor. The closer to 100%, the better the tactile sensation.

The surface smoothness can be obtained by taking a scanning electron micrograph of the particle, observing the unevenness of the particle surface, and determining the area of the recesses.

The cellulose derivative of the cellulose derivative particles of the present disclosure has a total substitution degree of 0.7 or more and 3 or less, preferably 1.0 or more and 3 or less, more preferably 1.4 or more and 3 or less, and 2.0 or more and 3 or less. is more preferred. This is because it is easy to produce spherical particles with excellent moldability and high sphericity.

If the total degree of substitution is less than 0.7, the water solubility is high, and the cellulose derivative is eluted in the step of extracting particles in the production of cellulose derivative particles described later, particularly in the step of removing the water-soluble polymer from the dispersion. In some cases, the sphericity of the resulting particles is reduced, and the tactile sensation is therefore inferior in some cases. In addition, the closer to 3, the lower the biodegradability of the cellulose derivative particles.

The total degree of substitution of cellulose derivatives can be measured by the following method. First, the total degree of substitution of the cellulose derivative is the sum of the degrees of substitution at the 2, 3, and 6 positions of the glucose ring of the cellulose derivative, and the degree of substitution at the 2, 3, and 6 positions of the glucose ring of the cellulose derivative is It can be measured by the NMR method according to the method of Tezuka (Carbonydr. Res. 273, 83 (1995)). That is, the free hydroxyl groups of the cellulose derivative are acylated with a carboxylic acid anhydride in pyridine. The type of carboxylic anhydride used here should be selected according to the purpose of analysis. For example, acetic anhydride is good for analyzing the degree of propionyl substitution of cellulose acetate propionate, and is preferably propionic anhydride. The solvent and acid anhydride for the acylation reaction may be appropriately selected according to the cellulose derivative to be analyzed.

A sample obtained by acylation is dissolved in deuterated chloroform, and the ¹³ C-NMR spectrum is measured. Taking as an example the case where the substituent is an acetyl group, a propionyl group, or a butyryl group, the carbon signal of the acetyl group is in the region of 169 ppm to 171 ppm from the high magnetic field in the order of 2-, 3-, and 6-positions, followed by the propionyl group. carbonyl carbon signals appear in the same order in the region from 172 ppm to 174 ppm, and butyryl group carbon signals appear in the region from 171 ppm to 173 ppm in the same order as the 2nd, 3rd, and 6th positions from the high magnetic field side. As another example, when a cellulose derivative having a propionyl group or a cellulose derivative having no propionyl group is treated with propionic anhydride for analytical purposes and the degree of propionyl substitution is analyzed, the carbonyl carbon of the propionyl group is The signals appear in the same order in the region from 172 ppm to 174 ppm.

Since the total degree of substitution of cellulose derivatives treated with carboxylic anhydride by Tezuka's method or a similar method is 3.0, the carbonyl carbon signal of the acyl group originally possessed by the cellulose derivative and the carbonyl of the acyl group introduced by the carboxylic anhydride treatment The sum of the areas of the signals is normalized to 3.0, and the abundance ratio of the acetyl group and the propionyl group at the corresponding positions (the area ratio of each signal) is obtained. Each degree of acyl substitution at the 6-position can be determined. Needless to say, substituents containing acyl groups that can be analyzed by this method are only substituents that do not correspond to the carboxylic anhydride used for the treatment for analytical purposes.

However, the total degree of substitution at the 2-, 3-, and 6-positions of the glucose ring of the cellulose derivative as a sample is 3.0, and the substituents are all limited substituents such as acetyl and propionyl groups. If this is known in advance, the NMR spectrum can be measured by directly dissolving the sample in deuterated chloroform, excluding the acylation step. If the substituents are all acetyl and propionyl groups, the carbon signals of the acetyl groups are in the region of 169 ppm to 171 ppm in the order 2, 3, 6 from the high magnetic field, as in the case involving the step of acylation. , the carbon signals of the propionyl group appear in the same order in the region from 172 ppm to 174 ppm, so from the abundance ratio of the acetyl group and the propionyl group at the corresponding positions (in other words, the area ratio of each signal), in the cellulose derivative Degrees of substitution such as acetyl and propionyl substitution at the 2-, 3-, and 6-positions of the glucose ring can be determined.

The cellulose derivative particles of the present disclosure may have a bulk specific gravity of 0.1 or more and 0.9 or less, 0.5 or more and 0.9 or less, or 0.6 or more and 0.9 or less. For example, when the particles are incorporated into cosmetics, the higher the bulk specific gravity of the particles, the better the fluidity of the cosmetic composition. Bulk specific gravity can be measured by a method based on JIS K 1201-1.

The cellulose derivative particles of the present disclosure preferably have a true specific gravity of more than 1, more preferably 1.04 or more, even more preferably 1.1 or more, and most preferably 1.2 or more. From the viewpoint of making the sphericity of the cellulose derivative fine particles 70% or more, it may be 1.35 or less. The true specific gravity is 2. of JIS Z 8807-1976 "Solid specific gravity measurement method". It can be measured by a pycnometer measurement method (liquid: water).

The true specific gravity is based on the density of water at 4° C.: 0.999973 g/cm ⁻³ .

The cellulose derivative particles of the present disclosure may or may not contain a plasticizer. A plasticizer in the present disclosure refers to a compound capable of increasing the plasticity of a cellulose derivative. The plasticizer is not particularly limited, and examples thereof include dimethyl adipate, dibutyl adipate, diisostearyl adipate, diisodecyl adipate, diisononyl adipate, diisobutyl adipate, diisopropyl adipate, and diethylhexyl adipate. Adipate plasticizers, including adipate esters such as dioctyl, dioctyldodecyl adipate, dicapryl adipate, and dihexyldecyl adipate; acetyltriethyl citrate, acetyltributyl citrate, isodecyl citrate, isopropyl citrate, triethyl citrate citrate plasticizers, including citrate esters such as , triethylhexyl citrate, and tributyl citrate; glutarate plasticizers, including glutarate esters such as diisobutyl glutarate, dioctyl glutarate, and dimethyl glutarate; succinic acid Succinate plasticizers, including succinate esters such as diisobutyl, diethyl succinate, diethylhexyl succinate, and dioctyl succinate; diisoamyl sebacate, diisooctyl sebacate, diisopropyl sebacate, diethyl sebacate, diethylhexyl sebacate, and sebacate plasticizers, including sebacate esters such as dioctyl sebacate; glycerol ester plasticizers, including glycerol alkyl esters such as triacetin, diacetin, and monoacetin; neopentyl glycol; and trioleyl phosphate, tristearyl phosphate, and phosphate-based plasticizers including phosphate esters such as tricetyl phosphate. These plasticizers may be used alone, or two or more plasticizers may be used in combination.

Citric acid-based plasticizers, including citric acid esters such as triethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate, among others; glycerol ester-based plasticizers, including glycerol alkyl esters such as triacetin, diacetin, and monoacetin; and at least one selected from the group consisting of adipic acid-based plasticizers such as diisononyl adipate, and is preferably selected from the group consisting of triethyl citrate, acetyltriethyl citrate, acetyltributyl citrate, triacetin, and diisononyl adipate. and more preferably at least one selected from the group consisting of acetyltriethyl citrate, triacetin, and diacetin. Although phthalic acid-based plasticizers can be used, they should be used with caution due to concerns about their similarity to endocrine disruptors.

When the cellulose derivative particles contain a plasticizer, the content of the plasticizer contained in the cellulose derivative particles is not particularly limited. For example, with respect to the weight of the cellulose derivative particles, it may be more than 0% by weight and 40% by weight or less, may be 0.01% by weight or more and 40% by weight or less, or may be 0.05% by weight or more and 35% by weight or less. may be 0.1 wt% or more and 30 wt% or less, may be 0.4 wt% or more and 20 wt% or less, may be 0.4 wt% or more and 15 wt% or less, and 0 0.4 wt % or more and 10 wt % or less, 0.4 wt % or more and 5 wt % or less, or 0.4 wt % or more and 2.5 wt % or less. The content of the plasticizer is preferably as low as possible, but a large content is permissible as long as the object of the present invention is not impaired.

The content of the plasticizer in the cellulose derivative particles is determined by dissolving the cellulose derivative particles in a solvent capable of dissolving the cellulose derivative particles and subjecting the solution to ¹ H-NMR measurement.

The cellulose derivative particles of the present disclosure can be produced by the below-described production method.

Since the cellulose derivative particles of the present disclosure have excellent tactile sensation, they can be suitably used, for example, in cosmetic compositions. In addition, due to its high sphericity, when blended in a cosmetic composition, it has the effect of filling unevenness in the skin to make it smooth and scattering light in various directions to make wrinkles less noticeable (soft focus). can get.

Cosmetic compositions include foundations such as liquid foundations and powder foundations; concealers; sunscreens; makeup bases; lipsticks and bases for lipsticks; and skin and hair external preparations mainly for cosmetic purposes, such as skin care lotions, which are not limited in dosage form. The dosage form may be any of liquid formulations such as aqueous solutions, emulsions and suspensions; semi-solid formulations such as gels and creams; solid formulations such as powders, granules and solid formulations. Further, it may be an emulsion dosage form such as cream or milky lotion; an oil gel dosage form such as lipstick; a powder dosage form such as foundation; and an aerosol dosage form such as hair styling agent.

A cosmetic composition containing the cellulose derivative particles of the present disclosure, particularly a liquid foundation, is excellent in spreading on the skin, covering spots and freckles, and slipperiness.

[Method for producing cellulose derivative particles]
In the method for producing cellulose derivative particles of the present disclosure, a cellulose derivative having a total degree of substitution of 0.7 or more and 3 or less and a water-soluble polymer are kneaded at 200° C. or more and 280° C. or less to use the cellulose derivative as a dispersoid. Obtaining a dispersion and removing the water-soluble polymer from the dispersion.

(Step of obtaining dispersion)
In the step of obtaining a dispersion, a cellulose derivative having a total degree of substitution of 0.7 or more and 3 or less and a water-soluble polymer are kneaded at 200° C. or more and 280° C. or less to obtain a dispersion containing the cellulose derivative as a dispersoid. obtain.

The kneading of the cellulose derivative and the water-soluble polymer can be performed using an extruder such as a twin-screw extruder. The kneading temperature refers to the cylinder temperature.

The dispersion may be extruded in the form of a string from a die attached to the tip of an extruder such as a twin-screw extruder, and then cut into pellets. At this time, the die temperature may be 220° C. or more and 300° C. or less.

The total degree of substitution of the cellulose acetate is 0.7 or more and 3 or less, preferably 1.0 or more and 3 or less, more preferably 1.4 or more and 3 or less, and even more preferably 2.0 or more and 3 or less. The total degree of substitution can be adjusted by adjusting the conditions of the aging process (conditions such as time and temperature).

The blending amount of the water-soluble polymer may be 55 parts by weight or more and 99 parts by weight or less with respect to 100 parts by weight as the total amount of the cellulose derivative and the water-soluble polymer. It is preferably 60 to 90 parts by weight, more preferably 65 to 85 parts by weight.

A water-soluble polymer as used herein refers to a polymer having an insoluble content of less than 50% by weight when 1 g of the polymer is dissolved in 100 g of water at 25°C. Examples of water-soluble polymers include polyvinyl alcohol, polyethylene glycol, sodium polyacrylate, polyvinylpyrrolidone, polypropylene oxide, polyglycerin, polyethylene oxide, vinyl acetate, modified starch, thermoplastic starch, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and Hydroxypropyl cellulose and the like can be mentioned. Among these, polyvinyl alcohol, polyethylene glycol and thermoplastic starch are preferred, and polyvinyl alcohol and thermoplastic starch are particularly preferred. Thermoplastic starch can be obtained by a known method. For example, Japanese Patent Publication No. 6-6307, WO92/
No. 04408 can be referred to, and more specifically, for example, tapioca starch mixed with about 20% glycerin as a plasticizer and kneaded by a twin-screw extruder can be used.

The resulting dispersion is a dispersion containing the water-soluble polymer as a dispersion medium and the cellulose derivative as a dispersoid. In other words, the water-soluble polymer may be the sea component, and the cellulose derivative may be the island component. In the dispersion, the kneaded material constituting the island component contains a cellulose derivative and is mainly spherical.

A cellulose derivative having a degree of substitution of 0.7 or more and 3 or less can be produced by a known derivative production method. When the cellulose derivative is a cellulose ester, for example, a step of activating the raw material pulp (cellulose); a step of acylating the activated cellulose with an esterifying agent (acylating agent); It can be produced through a step of deactivating the agent; and a step of maturing (saponifying, hydrolyzing) the produced cellulose acylate. Moreover, before the step of activating, a pretreatment step of sprinkling and mixing the raw material pulp with acetic acid after disintegration and crushing may be included. After the step of aging (saponification, hydrolysis), post-treatment steps of sedimentation, purification, stabilization and drying may be included.

When the cellulose derivative is cellulose ether, raw pulp ( cellulose) to obtain alkali cellulose, which is a precursor of cellulose ether; In addition, before the step of obtaining alkali cellulose, a pretreatment step of sprinkling and mixing the raw material pulp with acetic acid after disintegration and crushing may be included. After the step of slurrying (precipitating), post-treatment steps of precipitation separation, purification, stabilization and drying may be carried out.

(Step of removing water-soluble polymer)
The step of removing the water-soluble polymer from the dispersion will be described.

The method for removing the water-soluble polymer is not particularly limited as long as the water-soluble polymer can be dissolved and removed from the particles. Examples include water; alcohols such as methanol, ethanol, and isopropanol; , a method of dissolving and removing the water-soluble polymer in the dispersion using a solvent such as a mixed solution thereof. Specifically, for example, a method of removing the water-soluble polymer from the dispersion by, for example, mixing the dispersion and the solvent, filtering the mixture, and taking out the filter cake can be used.

As will be described later, when preparing a cellulose derivative impregnated with the plasticizer by mixing a cellulose derivative having a total degree of substitution of 0.7 or more and 3 or less and a plasticizer before the step of obtaining a dispersion, the dispersion In the step of removing the water-soluble polymer from the dispersion, the plasticizer may or may not be removed from the dispersion together with the water-soluble polymer. Therefore, the resulting cellulose derivative particles may or may not contain a plasticizer.

Regarding the mixing ratio of the dispersion and the solvent, the dispersion is preferably 0.01% by weight or more and 20% by weight or less, more preferably 2% by weight or more and 15% by weight or less, and 4% by weight based on the total weight of the dispersion and the solvent. Above 13% by weight is more preferable. If the content of the dispersion is higher than 20% by weight, the water-soluble polymer cannot be sufficiently dissolved and removed by washing, or the cellulose derivative particles that are not dissolved in the solvent and the water-soluble polymer that is dissolved in the solvent are mixed. becomes difficult to separate by operations such as filtration and centrifugation.

The temperature for mixing the dispersion and the solvent is preferably 0° C. or higher and 200° C. or lower, more preferably 20° C. or higher and 110° C. or lower, even more preferably 40° C. or higher and 80° C. or lower. When the temperature is lower than 0°C, the solubility of the water-soluble polymer becomes insufficient and it becomes difficult to remove it by washing. It becomes difficult to take out the particles.

The mixing time of the dispersion and the solvent is not particularly limited and may be adjusted as appropriate. can be

The mixing method is not limited as long as the water-soluble polymer can be dissolved. For example, by using a stirring device such as an ultrasonic homogenizer or a three-one motor, the water-soluble polymer can be efficiently removed from the dispersion even at room temperature. can do.

For example, when a three-one motor is used as the stirring device, the rotation speed during mixing of the dispersion and the solvent may be, for example, 5 rpm or more and 3000 rpm or less. Thereby, the water-soluble polymer can be removed from the dispersion more efficiently. It also effectively removes the plasticizer from the dispersion.

(Optional step: step of obtaining a cellulose derivative impregnated with a plasticizer)
The cellulose derivative having a total degree of substitution of 0.7 or more and 3 or less may be a cellulose derivative impregnated with a plasticizer, and the cellulose derivative having a total degree of substitution of 0.7 or more and 3 or less is prepared before the step of obtaining the dispersion. There may be a step of mixing the derivative with a plasticizer to obtain a cellulose derivative impregnated with said plasticizer. In this step, a cellulose derivative having a total substitution degree of 0.7 or more and 3 or less and a plasticizer are mixed.

Any plasticizer can be used without any particular limitation as long as it has a plasticizing effect in the melt-extrusion process of the cellulose derivative. can be used alone or in combination with two or more plasticizers.

Citric acid-based plasticizers, including citric acid esters such as triethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate, among the plasticizers exemplified above; glycerol esters, including glycerol alkyl esters such as triacetin, diacetin, and monoacetin. and at least one selected from the group consisting of adipic acid-based plasticizers such as diisononyl adipate, triethyl citrate, acetyltriethyl citrate, acetyltributyl citrate, triacetin, and diisononyl adipate. At least one selected from the group is more preferable, and at least one selected from the group consisting of acetyltriethyl citrate, triacetin, and diacetin is more preferable. Caution is required when using phthalate plasticizers due to concerns about their similarity to endocrine disruptors.

The blending amount of the plasticizer may be more than 0 parts by weight and 40 parts by weight or less, may be 2 parts by weight or more and 40 parts by weight or less, or 10 parts by weight with respect to the total amount of 100 parts by weight of the cellulose derivative and the plasticizer. parts or more and 30 parts by weight or less, or 15 parts by weight or more and 20 parts by weight or less. If it is too small, the sphericity of the obtained cellulose derivative particles tends to decrease, and if it is too large, the shape of the particles cannot be maintained and the sphericity tends to decrease.

The cellulose acetate derivative and the plasticizer can be mixed in a dry or wet manner using a mixer such as a Henschel mixer. When using a mixer such as a Henschel mixer, the temperature in the mixer may be a temperature at which the cellulose derivative does not melt, for example, in the range of 20°C or higher and lower than 200°C.

Also, the cellulose derivative and the plasticizer may be mixed by melt-kneading. Melt-kneading may be performed in combination with mixing using a mixer such as a Henschel mixer. In that case, mixing is performed using a mixer such as a Henschel mixer under a temperature condition of 20 ° C. or more and less than 200 ° C. Melt-kneading is preferably performed later. Since the plasticizer and the cellulose derivative are more uniformly compatible with each other in a short period of time, the sphericity of the finally prepared cellulose derivative particles is increased, and the tactile sensation and tactile sensation are improved.

Melt-kneading is preferably carried out by heating and mixing with an extruder. The kneading temperature (cylinder temperature) of the extruder may range from 200°C to 230°C. A uniform kneaded product can be obtained by plasticizing even at a temperature within this range. If the temperature is too low, the sphericity of the resulting particles will be low, resulting in poor tactile sensation and feel. In addition, the viscosity of the melt may decrease, resulting in insufficient kneading of the resin in the twin-screw extruder.

The melting point of the cellulose derivative is approximately 230° C. to 280° C., although it depends on the degree of substitution, and is close to the decomposition temperature of the cellulose derivative. This is because derivatives (flakes) can lower the plasticizing temperature. The kneading temperature (cylinder temperature) may be, for example, 200° C. when using a twin-screw extruder. The kneaded product may be extruded in the form of strands and cut into pellets by hot cutting or the like. The die temperature in this case may be about 220.degree.

EXAMPLES The present invention will be specifically described below with reference to examples, but the technical scope of the present invention is not limited by these examples.

(Example A-1)
100 parts by weight of cellulose acetate propionate (manufactured by Eastman Chemical Co., Ltd.: CAP-482-0.5) and 10 parts by weight of triacetin as a plasticizer are added to a twin-screw extruder equipped with a liquid addition device (PCM30 manufactured by Ikegai Co., Ltd., cylinder temperature: 200° C., die temperature: 220° C.), melt-kneaded, extruded and pelletized to obtain a kneaded product.

30 parts by weight of the resulting kneaded pellets and 70 parts by weight of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd.: melting point 190 ° C., saponification degree 99.1%) as a water-soluble polymer are blended in a dry state. It was supplied to a screw extruder (PCM30 manufactured by Ikegai Co., Ltd., cylinder temperature: 220°C, die temperature: 220°C) and extruded to form a dispersion.

Combined with pure water (solvent) so that the resulting dispersion is 5% by weight or less (weight of dispersion / (weight of dispersion + weight of pure water) × 100), Three-One Motor (manufactured by Shinto Kagaku Co., Ltd.) BL-3000), the mixture was stirred at a temperature of 80° C. and a rotation speed of 100 rpm for 3 hours. The solution after stirring was filtered with filter paper (No. 5A manufactured by ADVANTEC), and the filtered material was taken out. The removed filter cake is again prepared with pure water so that the content of the dispersion is 5% by weight or less, further stirred at a temperature of 80° C. and a rotation speed of 100 rpm for 3 hours, filtered, and the filter cake is taken out three times or more. Repeatedly, cellulose derivative particles (cellulose acetate propionate particles) were obtained. The degree of substitution of the obtained cellulose derivative particles was confirmed to be 2.58 (degree of acetyl substitution 0.18, degree of propionyl substitution 2.40) by measuring ¹ H-NMR.

The average particle size, particle size variation coefficient, sphericity, surface smoothness, bulk specific gravity, plasticizer content, true specific gravity, and tactile sensation of the obtained cellulose derivative particles were measured and evaluated. Results are shown in Table 1. Measurement and evaluation of each physical property were performed by the following methods.

<Average particle size and particle size variation coefficient>
Average particle size was measured using a dynamic light scattering method. First, pure water was used to adjust a sample to a concentration of about 100 ppm, and an ultrasonic oscillator was used to prepare a pure water suspension. After that, the volume The frequency particle size distribution was determined, and the average particle size was measured.The average particle size (nm, μm, etc.) referred to here is the value of the particle size corresponding to the cumulative scattering intensity of 50% in the volume frequency particle size distribution. The particle size variation coefficient (%) was calculated by (standard deviation of particle size/average particle size×100).

<Sphericality>
Using the image of the particles observed with a scanning electron microscope (SEM), the major axis and minor axis of 30 randomly selected particles are measured, the minor axis/major axis ratio of each particle is obtained, and the minor axis/major axis is obtained. The average value of the ratios was taken as the sphericity.

<Surface smoothness>
Scanning electron micrographs of the particles were taken at a magnification of 2500 to 5000 (see FIG. 1 for an example of the micrograph of the cellulose derivative particles), and the image was binarized using an image processor Winroof (manufactured by Mitani Shoji Co., Ltd.). (See FIG. 2 for the binarized image of the micrograph of FIG. 1). It may be any region smaller than the particle (eg, regions designated n1 and n2, referring to FIG. 2), including the center and/or near the center of a particle. Moreover, the size of the region may be 5 μm square when the particle diameter is 15 μm. The area ratio of the concave portion (shadow portion) of the unevenness in the region was calculated, and the surface smoothness (%) of one particle was calculated by the following formula.
Surface smoothness of one particle (%) = (1-concave area ratio) x 100
Area ratio of recesses=area of recesses in the arbitrary region/surface smoothness of the arbitrary region (%) was the average value of the surface smoothness of 10 randomly selected particle samples, that is, from n1 to n10. The higher the numerical value, the higher the surface smoothness.

<Bulk specific gravity>
It was measured according to "JIS K 1201-1".

<Plasticizer content>
The plasticizer content (% by weight) was determined by ¹ H-NMR measurement.

<True specific gravity>
JIS Z 8807-1976 "Solid specific gravity measurement method" 2. It was measured by the measurement method (liquid: water) using a pycnometer.

<Tactile sensation>
The tactile feel of the particles was sensory evaluated by a panel test of 20 people. The particles were touched, and both the smoothness and the moist feeling were comprehensively evaluated on a scale of 5 out of 5 according to the following criteria. The average score of 20 people was calculated.
Good: 5, Somewhat good: 4, Average: 3, Somewhat bad: 2, Bad: 1

(Example A-2)
Cellulose derivative particles) Cellulose acetate propio nate particles) were obtained. The degree of substitution of the obtained cellulose derivative particles was confirmed to be 2.58 (degree of acetyl substitution 0.18, degree of propionyl substitution 2.40) by measuring ¹ H-NMR.

(Example A-3)
Cellulose derivative particles (cellulose acetate butyrate particles) were obtained in the same manner as in Example A-2, except that cellulose acetate propionate was changed to cellulose acetate butyrate (manufactured by Eastman Chemical: CAB-171-15). rice field. The degree of substitution of the obtained cellulose derivative particles was confirmed to be 2.75 (degree of acetyl substitution: 2.04, degree of butyryl substitution: 0.71) by measuring ¹ H-NMR.

(Example A-4)
Cellulose stearate particles were obtained in the same manner as in Example A-2, except that cellulose acetate propionate was changed to cellulose stearate (C18) obtained by the following synthesis method.

<Method for synthesizing cellulose stearate>
Into a 100 L reactor equipped with a stirrer, reflux condenser, thermometer, and dropping funnel, 486 g of cellulose and 30 kg of pyridine were added, followed by 3450 g of stearyl chloride, and the temperature was maintained at 80° C.-100° C. under a nitrogen atmosphere. The temperature was raised to range and the reaction was allowed to continue stirring for 12 hours.

After completion of the reaction, the reaction mixture was poured into 90 kg of methanol to precipitate the intended crude cellulose derivative.

The precipitated crude cellulose derivative was separated by filtration, washed with methanol and separated by filtration three times, and then vacuum-dried at 90° C. for 8 hours to obtain 2120 g of the desired cellulose derivative particles. The degree of substitution of the obtained cellulose derivative particles (cellulose stearate particles) was confirmed to be 3.0 by measuring ¹ H-NMR.

(Example A-5)
Cellulose derivative particles (cellulose myristate particles) were obtained in the same manner as in Example A-4, except that 3450 g of stearic chloride was changed to 2881 g of myristic chloride (C ₁₄ H ₂₇ COCl). The resulting cellulose derivative particles weighed 2211 g and had a degree of substitution of 3.0.

(Example A-6)
Ethyl cellulose particles were obtained in the same manner as in Example A-2, except that cellulose acetate propionate was changed to ethyl cellulose (manufactured by Dow Chemical Co.: Ethocel Std. 10).

(Example A-7)
Methyloctyl cellulose particles were obtained in the same manner as in Example A-2, except that cellulose acetate propionate was changed to methyloctyl cellulose obtained by the synthesis method described below.

<Synthesis of methyloctyl cellulose>
2,000 g of methyl cellulose (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.: degree of methyl substitution: 1.8) and 40 L of dimethylacetamide were added to a 100 L reactor equipped with a stirrer, reflux condenser, thermometer, and dropping funnel. was stirred. Subsequently, 5,000 g of powdered sodium hydroxide was added, and the mixture was stirred for 1 hour. After returning to room temperature, 2 L of octyl iodide was added dropwise, stirred at room temperature for 30 minutes, and then stirred at 50° C. for 5 hours to cause a reaction.

After completion of the reaction, the temperature was returned to room temperature. 240 L of methanol was charged into the reactor with vigorous stirring to precipitate a white solid. After the white solid was separated by pressure filtration, it was washed twice with water. By heat-drying at 80° C. for 12 hours, 2,100 g of the target cellulose derivative was obtained. The total degree of substitution of the obtained cellulose derivative (methyloctyl cellulose) was 2.10 (degree of methyl substitution 1.8, degree of octyl substitution 0.3) by measuring ¹ H-NMR. confirmed.

Each physical property of the cellulose derivative particles obtained in each example was evaluated by the above measurement methods. Results are shown in Table 1.

(Comparative Example A-1)
For the nylon particles, Toray Nylon (registered trademark) Nylon 12 SP-500 (manufactured by Toray Industries, Inc.) was used. Each physical property of the particles was evaluated by the above measuring methods. Results are shown in Table 1.

(Comparative Example A-2)
Matsumoto Microsphere (registered trademark) M-100 (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) was used as acrylic particles. Each physical property of the particles was evaluated by the above measuring methods. Results are shown in Table 1.

(Comparative Example A-3)
Cellulose acetate particles used were Cellulo TA-25 (manufactured by JNC). Each physical property of the particles was evaluated by the above measuring methods. Results are shown in Table 1.

(Comparative Example A-4)
Cellulose particles used were Cellulose C-25 (manufactured by JNC). Each physical property of the particles was evaluated by the above measuring methods. Results are shown in Table 1.

As shown in Table 1, the cellulose derivative particles of Examples are all semi-synthetic polymers and have excellent tactile feel.

(Example B-1)
Preparation of Liquid Foundation After mixing each component shown in Table 2, they were well stirred and filled in a container to prepare a liquid foundation. Each physical property of the obtained liquid foundation was evaluated by the following methods. The results are shown in Table 3.

<Elongation to the skin>
Using a tactile measurement device (Static and Dynamic Friction Tester TL201Ts), the elongation length of 0.2 g of the liquid foundation was measured when it was run once.

<Covering power>
A small amount of the liquid foundation was applied to the skin, and spread 20 times with a finger to visually evaluate the degree of concealment of spots and freckles according to the following criteria.
◎: Sufficiently covered 〇: Covered △: Covered but insufficient ×: No covering power

<Uniformity>
A small amount of the liquid foundation was applied to the skin and spread 20 times with a finger, and the uniformity was visually evaluated according to the following criteria.
◎: Spread evenly 〇: Uniform △: Slightly mottled ×: Mottled

<Slipperiness>
A small amount of the liquid foundation was applied to the skin and spread with fingers 20 times to evaluate slipperiness (creaminess) according to the following criteria.
◎: Good slipperiness and sufficient creaminess 〇: Good slipperiness and creaminess △: Poor slippage ×: Not slippery

(Examples B-2 to 7)
Liquid foundation was prepared in the same manner as in Example B-1, except that the cellulose derivative particles obtained in Example A-1 in Table 2 were changed to the cellulose derivative particles obtained in Examples A-2 to A-7, respectively. was prepared. Each physical property of the obtained liquid foundation was evaluated by the methods described above. The results are shown in Table 3.

(Comparative Examples B-1 to 4)
A liquid foundation was prepared in the same manner as in Example B-1 except that the cellulose derivative particles obtained in Example A-1 in Table 2 were changed to the particles of Comparative Examples A-1 to A-4. Each physical property of the obtained liquid foundation was evaluated by the methods described above. The results are shown in Table 3.

As shown in Table 3, all of the cosmetic compositions containing the cellulose derivative particles of Examples B-1 to B-8 are excellent in spreadability on the skin, coverage of spots and freckles, and slipperiness.

Claims (15)

Cellulose derivative particles having an alkoxy group having 2 or more carbon atoms or an acyl group having 3 or more carbon atoms,
The cellulose derivative particles have an average particle diameter of 80 nm or more and 100 μm or less, a sphericity of 70% or more and 100% or less, a surface smoothness of 80% or more and 100% or less, and a bulk specific gravity of 0.5 or more and 0.9 or less. and
Cellulose derivative particles, wherein the total degree of substitution of the cellulose derivative is 0.7 or more and 3 or less. The cellulose derivative particles according to claim 1, wherein the total degree of substitution of the cellulose derivative is 2.0 or more and less than 2.6. The cellulose derivative particles according to claim 1 or 2, wherein the acyl group has 3 or more and 18 or less carbon atoms. The cellulose derivative particles according to any one of claims 1 to 3, wherein the alkoxy group has 2 or more and 8 or less carbon atoms. The cellulose derivative particles according to any one of claims 1 to 4, which have a true specific gravity of 1.04 or more. The cellulose derivative particles contain a plasticizer,
The cellulose derivative particles according to any one of claims 1 to 5, wherein the content of the plasticizer is more than 0% by weight and 40% by weight or less based on the weight of the cellulose derivative particles. The cellulose derivative particles according to claim 6, wherein the plasticizer is a glycerin ester plasticizer. A cosmetic composition containing the cellulose derivative particles according to any one of claims 1 to 7. a step of kneading a cellulose derivative having a total degree of substitution of 0.7 or more and 3 or less and a water-soluble polymer at 200° C. or more and 280° C. or less to obtain a dispersion containing the cellulose derivative as a dispersoid; The method for producing cellulose derivative particles according to any one of claims 1 to 7, comprising a step of removing the water-soluble polymer. The cellulose derivative having a total degree of substitution of 0.7 or more and 3 or less is a cellulose derivative impregnated with a plasticizer,
9. The cellulose derivative impregnated with the plasticizer is obtained by melt-kneading the cellulose derivative having a total degree of substitution of 0.7 or more and 3 or less and the plasticizer at a temperature of 20° C. or more and less than 200° C. The method for producing the cellulose derivative particles according to . The method for producing cellulose derivative particles according to claim 10, wherein the plasticizer is a glycerin ester plasticizer. The method for producing cellulose derivative particles according to claim 10, wherein the plasticizer is triacetin. The method for producing cellulose derivative particles according to any one of claims 9 to 12, wherein the water-soluble polymer is polyvinyl alcohol or thermoplastic starch. The water-soluble polymer is removed from the dispersion by mixing the dispersion and a solvent to dissolve the water-soluble polymer in the solvent. A method for producing cellulose derivative particles. 15. The method for producing cellulose derivative particles according to claim 14, wherein the mixing ratio of the dispersion and the solvent is 0.01% by weight or more and 20% by weight or less of the dispersion with respect to the total weight of the dispersion and the solvent. .

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