Cellulose acylate composition and method for producing the same

Abstract

This cellulose acylate composition comprises cellulose acylate particles and particles including one or more metal compounds. The cellulose acylate has a total degree of substitution of 0.7-2.9. The metal compounds are one or more compounds selected from among alkali metal compounds and alkaline-earth metal compounds. This composition is produced by adding one or more metal compounds selected from among alkali metal compounds and alkaline-earth metal compounds, during and / or after a step in which a water-soluble polymer is removed from a dispersion containing a plasticizer-impregnated cellulose acylate as a dispersed phase to obtain cellulose acylate particles.

Description

Technical Field

[0001] The present disclosure relates to a cellulose acetate composition and a method for producing the same. Specifically, the present disclosure relates to a cellulose acetate composition used in a cosmetic composition and a method for producing the same.

Background Art

[0002] Conventionally, various polymer microparticles have been blended in cosmetics for the purposes of improving elongation, changing the touch, imparting a wrinkle-smoothing effect, and improving the slipperiness of foundations and the like. In particular, microparticles with a high degree of sphericity have excellent touch, and a light scattering (soft focus) effect can be obtained depending on their physical properties and shape. When such microparticles are used in foundations and the like, it is expected to fill in the irregularities of the skin to make it smooth and scatter light in various directions to make wrinkles and the like less noticeable (soft focus) effect.

[0003] As such microparticles to be blended in cosmetics, microparticles made of synthetic polymers such as polyamide, polymethyl methacrylate (PMMA), polystyrene, polypropylene, and polyethylene have been used. However, in recent years, in consideration of the environment, instead of these synthetic polymers, the application of microparticles made of cellulose, which is a natural polymer, or cellulose derivatives, which are semi-synthetic polymers, has been studied.

[0004] Patent Document 1 describes a method including a step of forming a polysaccharide ester product from polysaccharide synthesis, the step in which the polysaccharide ester product contains a polysaccharide ester and a solvent; a step of diluting the polysaccharide ester product to thereby provide a polysaccharide ester dope; and a step of forming a plurality of polysaccharide ester microspheres from the polysaccharide ester dope, and a cosmetic composition is cited as an article that can contain the polysaccharide ester microspheres.

[0005] Patent Document 2 describes a cellulose acylate in which the volume-average particle size 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 2.6 or less. It also describes a preferred method for producing cellulose acylate, comprising an acylation step of acyling cellulose in the presence of sulfuric acid and a deacylation step of deacyling the acyled cellulose in a polar solvent in the presence of acetic acid.

[0006] Patent Document 3 describes a method of preparing a dispersion by kneading a resin component (A), such as a thermoplastic resin, with a water-soluble auxiliary component (B), eluting the auxiliary component (B) from this dispersion, and producing a molded article (for example, a porous body or spherical particles) composed of the resin component (A). The patent document also describes cellulose derivatives such as cellulose acetate as the resin component (A).

[0007] Patent Document 4 discloses cellulose acetate particles having an average particle diameter of 80 nm to 100 μm, a sphericity of 0.7 to 1.0, a surface smoothness of 80% to 100%, and a total acetyl substitution degree of 0.7 to 2.9. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Special Publication No. 2016-500129 [Patent Document 2] Patent No. 6187653 [Patent Document 3] Japanese Patent Publication No. 2004-051942 [Patent Document 4] Patent No. 6609726 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, the polysaccharide stelmiclospheres described in Patent Document 1 are porous particles with large particle size and a broad particle size distribution, and are not sufficient as a substitute for fine particles of synthetic polymers used in cosmetics and the like. Furthermore, the cellulose acylate obtained by the manufacturing method described in Patent Document 2 is also an amorphous, porous particle. Moreover, the particulate molded articles obtained by the manufacturing method described in Patent Document 3 have low sphericity and are only roughly spherical.

[0010] The cellulose acetate particles disclosed in Patent Document 4 are said to have excellent tactile properties due to their high sphericity and surface smoothness, and to produce a light scattering (soft focus) effect when incorporated into cosmetic compositions. In the field of cosmetic compositions, there is a strong demand for fine particles that conform to the standards for quasi-drug raw materials. There is a need for fine particles that can be incorporated into cosmetic compositions while conforming to these standards (especially pH standards) without changing over time even during long-term storage. There is still room for further improvement in the long-term stability of conventionally known cellulose acetate particles.

[0011] The purpose of this disclosure is to provide a cellulose acylate composition and a method for producing the same, which have improved stability over time and maintain excellent physical properties from the initial stages of production for a long period of time. [Means for solving the problem]

[0012] As a result of diligent research, the inventors have found that acetic acid and other substances bound to cellulose acylate detach as free acids over time, causing the pH to deviate from the pH range (6.0-8.0) specified in the standards for quasi-drug raw materials, and furthermore, potentially becoming a source of odor generation.

[0013] That is, the cellulose acylate composition according to this disclosure comprises cellulose acylate particles and metal compound-containing particles. The total degree of substitution of the cellulose acylate is 0.7 or more and 2.9 or less. The metal compound is one or more selected from alkali metal compounds and alkaline earth metal compounds.

[0014] Preferred metal compounds are hydroxides, oxides, or carbonates of alkali metals or alkaline earth metals. A preferred alkali metal is sodium. Preferred alkaline earth metals are calcium or magnesium.

[0015] Preferably, the average particle size of the metal compound-containing particles is 20 nm or more and 20 μm or less. Preferably, the metal compound-containing particles are aggregates.

[0016] Preferably, this cellulose acylate composition contains alkali metals and alkaline earth metals in a total concentration of 50 ppm to 2000 ppm.

[0017] Preferably, the average particle diameter of the cellulose acylate particles is 80 nm to 100 μm. Preferably, the sphericity of the cellulose acylate particles is 0.7 to 1.0. Preferably, the surface smoothness of the cellulose acylate particles is 80% to 100%.

[0018] Preferably, the substituents on the cellulose acylate are acyl groups having 2 to 20 carbon atoms. Preferred acyl groups are selected from acetyl, propionyl, and butyryl groups.

[0019] Preferably, the cellulose acylate particles contain a plasticizer. The plasticizer content is 2% by weight or more and 40% by weight or less relative to the cellulose acylate particles. The preferred plasticizer is one or more selected from the group consisting of citric acid-based plasticizers, glycerin ester-based plasticizers, adipic acid-based plasticizers, and phthalic acid-based plasticizers.

[0020] The cosmetic composition of this disclosure comprises any of the cellulose acylate compositions described above.

[0021] The method for producing the cellulose acylate composition described herein is: (1) A first step in which a cellulose acylate with a total substitution degree of 0.7 or more and 2.9 or less is mixed with a plasticizer to obtain a cellulose acylate impregnated with a plasticizer. (2) A second step of kneading the cellulose acylate impregnated with a plasticizer and a water-soluble polymer at 200°C or higher and 280°C or lower to obtain a dispersion having the cellulose acylate impregnated with a plasticizer as a dispersion medium and (3) A third step of removing the water-soluble polymer from the dispersion to obtain cellulose acylate particles This production method includes adding one or more metal compounds selected from alkali metal compounds and alkaline earth metal compounds to the cellulose acylate particles during and / or after the third step.

[0022] Preferably, during the third step, the dispersion is washed at least once with a solution containing a metal compound, whereby the metal compound is added. Preferably, the solution containing the metal compound is an aqueous solution.

[0023] Preferably, the addition amount of the metal compound with respect to 100 parts by weight of the cellulose acylate particles is 0.01 part by weight or more and 1.0 part by weight or less.

Advantages of the Invention

[0024] The cellulose acylate composition of the present disclosure contains alkali metal compound-containing particles and / or alkaline earth metal compound-containing particles. The desorption of free acid from the cellulose acylate is suppressed by these metal compound-containing particles. According to this cellulose acylate composition, changes over time due to the desorption of free acid can be avoided. This cellulose acylate composition has excellent stability over time. Further, in a cosmetic composition containing this cellulose acylate composition, excellent physical properties at the initial stage of production are exhibited even after a long period of time.

Brief Description of the Drawings

[0025] [Figure 1] FIG. 1 is an electron micrograph of the cellulose acylate composition of Example 1. [Figure 2] FIG. 2 is an electron micrograph of Comparative Example 1.

Best Mode for Carrying Out the Invention

[0026] The following describes a specific example of a preferred embodiment. Each configuration and combination thereof in each embodiment is an example, and additions, omissions, substitutions, and other modifications are possible as appropriate, without departing from the spirit of this disclosure. This disclosure is not limited by the embodiments, but is limited only by the scope of the claims. Furthermore, each aspect disclosed herein can be combined with any other features disclosed herein.

[0027] In this specification, "X~Y" indicating a range means "X or greater and Y or less." Also, unless otherwise noted, all test temperatures are room temperature (20℃±5℃).

[0028] [Cellulose acylate composition] The cellulose acylate composition of this disclosure comprises cellulose acylate particles and metal compound-containing particles. The total degree of substitution of the cellulose acylate is 0.7 to 2.9. The metal compound is one or more selected from alkali metal compounds and alkaline earth metal compounds. The cellulose acylate composition may contain other metal compounds as unavoidable impurities.

[0029] [Metal compound-containing particles] In the cellulose acylate composition of this disclosure, the main component of the metal compound-containing particles is a metal compound selected from alkali metal compounds and alkaline earth metal compounds. These metal compound-containing particles function as a neutralizing agent for the cellulose acylate particles. These metal compound-containing particles contribute to suppressing the detachment of acetic acid and other substances bound to the cellulose acylate. In this cellulose acylate composition, a decrease in pH due to the generation of free acids such as acetic acid is avoided, so for example, even during long-term storage, the pH is maintained within the range specified in the standards for quasi-drug raw materials, and the generation of odors caused by acetic acid and other substances is also suppressed. The inclusion of these metal compound-containing particles improves the long-term stability of the cellulose acylate composition.

[0030] Furthermore, in the cellulose acylate composition of this disclosure, the metal compound-containing particles exist substantially independently of the cellulose acylate particles and are different from metal compounds that are present due to additives or impurities during the manufacturing of the raw material cellulose acylate. According to the inventors' findings, these metal compound-containing particles function as an antiblocking agent, suppressing the aggregation of cellulose acylate particles. As a result, the cellulose acylate composition of this disclosure improves not only the tactile properties such as smoothness and moisture, but also the tactile properties in the sense that it is less prone to clumping. When the cellulose acylate composition of this disclosure is incorporated into a cosmetic composition, the excellent quality at the time of manufacture can be maintained at a high level for a long period of time.

[0031] Examples of metal compounds include alkali metals such as sodium, lithium, and potassium, or alkaline earth metals such as calcium, magnesium, and barium. Sodium is preferred as the alkali metal, and calcium and magnesium are preferred as the alkaline earth metals. Examples include hydroxides such as sodium hydroxide, calcium hydroxide, and magnesium hydroxide; oxides such as sodium oxide, calcium oxide, and magnesium oxide; and carbonates such as sodium carbonate, calcium carbonate, and magnesium carbonate. Calcium carbonate, calcium hydroxide, magnesium carbonate, and magnesium hydroxide are more preferred. For example, when the metal compound is calcium hydroxide, calcium carbonate may be produced by reaction with carbon dioxide in the air; such cellulose acylate compositions are also included within the technical scope of this application.

[0032] The average particle diameter of the metal compound-containing particles is preferably 20 nm or more and 20 μm or less. From the viewpoint of ease of manufacturing, the average particle diameter of the metal compound-containing particles is more preferably 50 nm or more, and even more preferably 1 μm or more. From the viewpoint of improving tactile feel, the average particle diameter of the metal compound-containing particles is more preferably 15 μm or less, and even more preferably 12 μm or less. The average particle diameter of the metal compound-containing particles is obtained by measuring the major and minor axes of each particle using images of particles observed with a scanning electron microscope (SEM), calculating the average value, and then taking the number average of 30 randomly selected particles.

[0033] In the cellulose acylate composition of this disclosure, the metal compound-containing particles may be aggregates. When the metal compound-containing particles are aggregates, it is preferable that the average particle size of these aggregates is within the aforementioned numerical range.

[0034] The content of metal compound-containing particles in the cellulose acylate composition of this disclosure is not particularly limited, but it is preferable that the total concentration of alkali metals and alkaline earth metals is between 50 ppm and 2000 ppm. In a cellulose acylate composition containing a total of 50 ppm or more of alkali metals and alkaline earth metals, the decrease in pH is effectively suppressed and the stability over time is improved. If the total concentration of alkali metals and alkaline earth metals exceeds 2000 ppm, the pH may become high outside the desired range during manufacturing. The metal concentration in the cellulose acylate composition is measured by the absorbance method using an atomic absorption spectrophotometer. Details will be described later in the examples.

[0035] [Cellulose acylate particles] The average particle size of cellulose acylate particles may be 80 nm to 100 μm, 100 nm or more, 1 μm or more, 2 μm or more, or 4 μm or more. Alternatively, 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 feel will be inferior, and the light scattering (soft focus) effect will be reduced. Conversely, if the average particle size is too small, manufacturing will be difficult. Regarding tactile feel, this refers not only to direct contact with cellulose acylate particles, but also to the feel and texture when incorporated into cosmetic compositions, for example.

[0036] The average particle size can be measured using dynamic light scattering. Specifically, the procedure is as follows: First, cellulose acylate particles are added to pure water to a concentration of 100 ppm, and the sample is prepared by creating a pure water suspension using an ultrasonic vibrator. Then, the volume frequency particle size distribution is measured by laser diffraction (Horiba, Ltd. "Laser Diffraction / Scattering Particle Size Distribution Analyzer LA-960", ultrasonic treatment for 15 minutes, refractive index (1.500, medium (water; 1.333))). In this volume frequency particle size distribution, the particle size corresponding to 50% of the integrated scattering intensity is determined as the average particle size. That is, the average particle size (nm or μm) in this specification is the volume-based median diameter.

[0037] The coefficient of variation of particle size for cellulose acylate particles may be between 0% and 60%, and between 2% and 50%. The coefficient of variation (%) can be calculated by the formula: standard deviation of particle size / average particle size × 100.

[0038] The sphericity of the cellulose acylate particles is preferably 0.7 to 1.0, more preferably 0.8 to 1.0, and even more preferably 0.9 to 1.0. If the sphericity is less than 0.7, the texture is inferior, and for example, when incorporated into a cosmetic composition, the skin feel and soft-focus effect are reduced.

[0039] Sphericity can be measured by the following method: Using images of particles observed with a scanning electron microscope (SEM), the major and minor axes of 30 randomly selected particles are measured, the minor axis / major axis ratio for each particle is determined, and the average of these minor axis / major axis ratios is taken as the sphericity. The closer the sphericity is to 1, the more perfectly spherical the particle is considered to be.

[0040] The surface smoothness of the cellulose acylate particles is preferably 80% to 100%, more preferably 85% to 100%, and even more preferably 90% to 100%. If the surface smoothness is less than 80%, the tactile feel is inferior. The closer the surface smoothness is to 100%, the more desirable the tactile feel is obtained.

[0041] Surface smoothness can be determined by taking scanning electron microscope images of the particles, observing the surface irregularities, and determining the area of ​​the depressions. Further details will be described in the examples below.

[0042] The cellulose acylate forming the cellulose acylate particles has a total substitution degree of 0.7 to 2.9, preferably 0.7 to less than 2.6, more preferably 1.0 to less than 2.6, and even more preferably 2.0 to less than 2.6. This is because it allows for the easy production of spherical particles with excellent moldability and high sphericity.

[0043] If the total degree of substitution is less than 0.7, the water solubility increases, and in the particle extraction process in the production of cellulose acylate particles described later, particularly in the process of removing water-soluble polymers from the dispersion, the cellulose acylate is more likely to leach out, which may reduce the sphericity of the resulting particles, and thus may result in an inferior tactile feel.

[0044] The total degree of substitution of cellulose acylate can be measured by the following method. First, the total degree of substitution of cellulose acylate is the sum of the individual substitution degrees at positions 2, 3, and 6 of the glucose ring of the cellulose acylate. These individual substitution degrees at positions 2, 3, and 6 of the glucose ring of the cellulose acylate can be measured by NMR according to the method of Tezuka (Carbonydr. Res. 273, 83 (1995)). Specifically, the free hydroxyl group of the cellulose acylate is acylated with a carboxylic acid anhydride in pyridine. The type of carboxylic acid anhydride used should be selected according to the purpose of the analysis. For example, acetic anhydride is suitable for analyzing the degree of propionyl substitution of cellulose acetate propionate, while propionic anhydride is suitable for analyzing the degree of acetyl substitution. The solvent and acid anhydride for the acylation reaction should be appropriately selected according to the cellulose acylate to be analyzed.

[0045] The sample obtained by acylation was dissolved in deuterated chloroform. 13 The 1C-NMR spectrum is measured. For example, when the substituent is an acetyl group, propionyl group, or butyryl group, the carbon signal of the acetyl group appears in the region from 169 ppm to 171 ppm in the order of positions 2, 3, and 6 from the high magnetic field side, the carbonyl carbon signal of the propionyl group appears in the region from 172 ppm to 174 ppm in the same order, and the carbon signal of the butyryl group appears in the region from 171 ppm to 173 ppm in the same order of positions 2, 3, and 6 from the high magnetic field side. To give another example, when analyzing cellulose acylate with a propionyl group, or when analyzing the degree of propionyl substitution after treating cellulose acylate without a propionyl group with propionic anhydride, the carbonyl carbon signal of the propionyl group appears in the region from 172 ppm to 174 ppm in the same order.

[0046] According to Tezuka's method or a similar method, the total degree of substitution of cellulose acylate treated with carboxylic anhydride is 3.0. Therefore, by normalizing the sum of the areas of the carbonyl carbon signals of the acyl groups originally present in cellulose acylate and the carbonyl signals of the acyl groups introduced by the carboxylic anhydride treatment to 3.0, and determining the relative abundance of acetyl groups and propionyl groups at the corresponding positions (area ratio of each signal), the degrees of acyl substitution at positions 2, 3, and 6 of the glucose ring in the original cellulose acylate can be determined. Needless to say, the substituents containing acyl groups that can be analyzed by this method are only those substituents that do not correspond to the carboxylic anhydride used in the analytical treatment.

[0047] However, if the total degree of substitution at positions 2, 3, and 6 of the glucose ring of the cellulose acylate sample is known to be 3.0, and all substituents are limited substituents such as acetyl and propionyl groups, then the NMR spectrum can be measured by directly dissolving the sample in deuterated chloroform, excluding the acylation step. If all substituents are acetyl and propionyl groups, then, similar to the case including the acylation step, the carbon signals of the acetyl groups will appear in the region from 169 ppm to 171 ppm in the order of positions 2, 3, and 6 from the highest magnetic field, and the carbon signals of the propionyl groups will appear in the region from 172 ppm to 174 ppm in the same order. Therefore, the degree of substitution, such as the degree of acetyl and propionyl substitution at positions 2, 3, and 6 of the glucose ring in the cellulose acylate, can be determined from the relative abundance of acetyl and propionyl groups at the corresponding positions (in other words, the area ratio of each signal).

[0048] The cellulose acylate forming the cellulose acylate particles of this disclosure preferably has an acyl group having 2 to 20 carbon atoms. The acyl group may have 3 or more carbon atoms, or 4 or more carbon atoms. The acyl group may have 18 or fewer carbon atoms, or 16 or fewer carbon atoms. The cellulose acylate may have two or more acyl groups with different numbers of carbon atoms.

[0049] Examples of acyl groups having 2 to 20 carbon atoms include acetyl, propionyl, butyryl, pentanoyl(valeryl), hexanoyl, heptanoyl, octanoyl, nonanoyl, undecanoyl, dodecanoyl, tridecanoyl, tetradecanoyl(myristoyl), pentadecanoyl, hexadecanoyl, heptadecanoyl, and octadecanoyl(stearoyl). One or more acyl groups selected from acetyl, propionyl, and butyryl are preferred.

[0050] Cellulose acylate particles may or may not contain a plasticizer. In this disclosure, a plasticizer means a compound that can increase the plasticity of cellulose acylate. The plasticizer is not particularly limited and includes, for example, adipic acid-based plasticizers containing adipic acid esters such as dimethyl adipate, dibutyl adipate, diisostearyl adipate, diisodecyl adipate, diisononyl adipate, diisobutyl adipate, diisopropyl adipate, diethylhexyl adipate, dioctyl adipate, dioctyldodecyl adipate, dicapryl adipate and dihexyldecyl adipate; citrate-based plasticizers containing citrate esters such as acetyltriethyl citrate, acetyltributyl citrate, isodecyl citrate, isopropyl citrate, triethyl citrate, triethylhexyl citrate and tributyl citrate; and diisobutyl glutarate and dioctyl glutarate. Examples include glutaric acid-based plasticizers containing glutaric acid esters such as dimethyl glutarate; succinic acid-based plasticizers containing succinic acid esters such as diisobutyl succinate, diethyl succinate, diethylhexyl succinate, and dioctyl succinate; sebacate-based plasticizers containing sebacate acid esters such as diisoamyl sebacate, diisooctyl sebacate, diisopropyl sebacate, diethyl sebacate, diethylhexyl sebacate, and dioctyl sebacate; glycerin ester-based plasticizers containing glycerin alkyl esters such as triacetin, diacetin, and monoacetin; neopentyl glycol; and phosphate-based plasticizers containing phosphate esters such as trioleyl phosphate, tristearyl phosphate, and tricetyl phosphate. These plasticizers may be used alone or in combination of two or more plasticizers.

[0051] Among these, one or more selected from the group consisting of citrate-based plasticizers including citrate esters such as triethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate; glycerin ester-based plasticizers including glycerin alkyl esters such as triacetin, diacetin, and monoacetin; and adipic acid-based plasticizers such as diisononyl adipate are preferred, one or more selected from the group consisting of triethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, triacetin, and diisononyl adipate are more preferred, and one or more selected from the group consisting of acetyl triethyl citrate, triacetin, and diacetin are even more preferred. Phthalate-based plasticizers can be used, but caution is required when using them due to concerns about their similarity to endocrine disruptors.

[0052] When cellulose acylate particles contain a plasticizer, the amount of plasticizer contained in the cellulose acylate particles is not particularly limited. For example, the amount may be greater than 0% by weight and 40% by weight or less, 2% by weight or more and 40% by weight or less, 10% by weight or more and 30% by weight or less, or 15% by weight or more and 20% by weight or less, relative to the weight of the cellulose acylate particles.

[0053] The plasticizer content in cellulose acylate particles is determined by dissolving the cellulose acylate particles in a solvent capable of dissolving them, and then determining the solution. 1 It can be determined by measurement using H-NMR.

[0054] The cellulose acylate composition of this disclosure can be produced by the manufacturing method described later.

[0055] The cellulose acylate composition disclosed herein is suitable for use in cosmetic compositions due to its high stability over time and excellent tactile properties. Furthermore, because it has high sphericity, when incorporated into cosmetic compositions, it fills in skin irregularities, making the skin smooth and scattering light in various directions to reduce the appearance of wrinkles (soft focus effect). Moreover, with the cellulose acylate composition disclosed herein, these excellent physical properties immediately after manufacturing can be maintained for a long period of time.

[0056] Cosmetic compositions include foundations such as liquid foundations and powder foundations; concealers; sunscreens; makeup bases; lipstick and lip primers; face powders such as body powders, solid face powders and face powders; solid powder eyeshadows; wrinkle-concealing creams; and skincare lotions, and are not limited to external preparations for skin and hair primarily for cosmetic purposes. Dosage forms may include liquid preparations such as aqueous solutions, emulsions, and suspensions; semi-solid preparations such as gels and creams; and solid preparations such as powders, granules, and solids. They may also be emulsion preparations such as creams and emulsions; oil-gel preparations such as lipsticks; powder preparations such as foundations; and azole preparations such as hair styling products.

[0057] [Method for producing cellulose acylate composition] The method for producing the cellulose acylate composition of this disclosure comprises: a first step of mixing cellulose acylate having a total substitution degree of 0.7 to 2.9 with a plasticizer to obtain cellulose acylate impregnated with a plasticizer; a second step of kneading the plasticizer-impregnated cellulose acylate with a water-soluble polymer at 200°C to 280°C to obtain a dispersion in which the plasticizer-impregnated cellulose acylate is dispersed; and a third step of removing the water-soluble polymer from the dispersion to obtain cellulose acylate particles. The cellulose acylate composition of this disclosure is produced by adding one or more metal compounds selected from alkali metal compounds and alkaline earth metal compounds to the cellulose acylate particles during and / or after the third step.

[0058] (First step) In the first step of obtaining cellulose acylate impregnated with a plasticizer, cellulose acylate with a total substitution degree of 0.7 to 2.9 is mixed with a plasticizer.

[0059] Cellulose acylates with a total substitution degree of 0.7 to 2.9 can be produced by known manufacturing methods. For example, they can be produced by a process of activating raw material pulp (cellulose); acyling the activated cellulose with an esterifying agent (acyling agent); deactivating the acyling agent after the acyling reaction is complete; and maturing (saponification, hydrolysis) the produced cellulose acylate. Alternatively, a pretreatment step may be included before the activation step, in which the raw material pulp is disintegrated and crushed, and then sprayed and mixed with acetic acid. After the maturation (saponification, hydrolysis) step, a posttreatment step may be included, in which precipitation separation, purification, stabilization, and drying are performed.

[0060] The total degree of substitution of the cellulose acylate can be adjusted by adjusting the conditions of the maturation process (time, temperature, etc.). The type of substituent can be determined by selecting an esterifying agent. The total degree of substitution of the resulting cellulose acylate is between 0.7 and 2.9, preferably between 0.7 and 2.6, more preferably between 1.0 and 2.6, even more preferably between 1.4 and 2.6, and particularly preferably between 2.0 and 2.6.

[0061] As a plasticizer, any plasticizer that has a plasticizing effect in the melt extrusion process of cellulose acylate can be used without particular limitations. Specifically, the aforementioned plasticizers can be used individually or in combination of two or more as plasticizers contained in the cellulose acylate particles. One or more selected from the group consisting of citric acid-based plasticizers, glycerin ester-based plasticizers, adipic acid-based plasticizers, and phthalate-based plasticizers are preferred, and one or more selected from the group consisting of acetyltriethyl citrate, triacetin, diacetin, and diethyl phthalate are even more preferred.

[0062] The amount of plasticizer added may be more than 0 parts by weight and 40 parts by weight or less, 2 parts by weight or more and 40 parts by weight or less, 10 parts by weight or more and 30 parts by weight or less, or 15 parts by weight or more and 20 parts by weight or less, based on 100 parts by weight of the total amount of cellulose acylate and plasticizer. If the amount is too small, the sphericity of the resulting cellulose acylate particles tends to decrease, and if the amount is too large, the particle shape cannot be maintained and the sphericity tends to decrease.

[0063] The mixing of cellulose acylate and plasticizer can be carried out dry or wet using a mixer such as a Henschel mixer. When using a mixer such as a Henschel mixer, the temperature inside the mixer may be set to a temperature at which the cellulose acylate does not melt, for example, in the range of 20°C to less than 200°C.

[0064] The mixing of cellulose acylate and plasticizer may be carried out by melt kneading. Melt kneading may be combined with mixing using a mixer such as a Henschel mixer, in which case it is preferable to mix using a mixer such as a Henschel mixer at a temperature of 20°C to less than 200°C, and then perform melt kneading. By allowing the plasticizer and cellulose acylate to blend more uniformly and in a shorter time, the sphericity of the resulting cellulose acylate particles increases, resulting in a better feel and texture.

[0065] Melt mixing can be performed by heating and mixing in an extruder. The mixing temperature (cylinder temperature) of the extruder may be 200°C to 230°C. Plasticization and a uniform mixture can be obtained even at temperatures within this range. If the temperature is too low, the sphericity of the resulting particles will decrease, resulting in a reduced feel and texture. If the temperature is too high, the mixture may undergo thermal deterioration or discoloration. In addition, the viscosity of the molten material may decrease, potentially leading to insufficient mixing of the resin within the extruder.

[0066] The melting point of cellulose acylate is approximately 230°C to 280°C, depending on the type and degree of substituent. Since this is close to the decomposition temperature of cellulose acylate, melt mixing is usually difficult within this temperature range. However, with cellulose acylate (flakes) impregnated with plasticizers, the plasticization temperature can be lowered. The mixing temperature (cylinder temperature) may be as low as 200°C, for example, when using a twin-screw extruder. The mixed material can be extruded into strands and then formed into pellets by hot cutting or other methods. In this case, the die temperature may be around 220°C.

[0067] (Second step) In the second step, the cellulose acylate impregnated with a plasticizer and a water-soluble polymer are kneaded at a temperature of 200°C to 280°C to obtain a dispersion in which the cellulose acylate is dispersed.

[0068] The mixing of cellulose acylate impregnated with plasticizer and water-soluble polymers can be carried out using an extruder such as a twin-screw extruder. The mixing temperature refers to the cylinder temperature.

[0069] The dispersion may be extruded in a string-like form from a die attached to the tip of an extruder such as a twin-screw extruder, and then cut to form pellets. In this case, the die temperature may be between 220°C and 300°C.

[0070] The amount of water-soluble polymer added may be 55 parts by weight or more and 99 parts by weight or less, based on 100 parts by weight of the total amount of cellulose acylate impregnated with plasticizer and water-soluble polymer. Preferably, it is 60 parts by weight or more and 90 parts by weight or less, and more preferably 65 parts by weight or more and 85 parts by weight or less.

[0071] In this specification, a water-soluble polymer refers to a polymer in which, when 1 g of the polymer is dissolved in 100 g of water at 25°C, the insoluble content is less than 50% by weight. Examples of such water-soluble polymers include polyvinyl alcohol, polyethylene glycol, sodium polyacrylate, polyvinylpyrrolidone, polypropylene oxide, polyglycerin, polyethylene oxide, vinyl acetate, modified starch, thermoplastic starch, methylcellulose, ethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose. 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 known methods. For example, Japanese Patent Publication No. 6-6307 and WO92 / 04408 can be referenced, and more specifically, for example, tapioca starch mixed with about 20% glycerin as a plasticizer and kneaded in a twin-screw extruder can be used.

[0072] The dispersion obtained in the second step is a dispersion in which a water-soluble polymer is the dispersion medium and cellulose acylate impregnated with a plasticizer is the dispersed phase. In other words, the water-soluble polymer is the sea component and the cellulose acylate impregnated with a plasticizer is the island component. In this dispersion, the compound constituting the island component contains cellulose acylate and a plasticizer and is mainly spherical.

[0073] (Third step) In the third step to obtain cellulose acylate particles, the water-soluble polymer is removed from the aforementioned dispersion.

[0074] The method for removing water-soluble polymers is not particularly limited, as long as the water-soluble polymers can be dissolved and removed from the particles. For example, a method can be used to dissolve and remove water-soluble polymers in a dispersion using a solvent such as water, methanol, ethanol, isopropanol, or a mixture thereof. Specifically, for example, a method can be used to remove water-soluble polymers from a dispersion by mixing the dispersion with a solvent and then separating the solvent containing the dissolved water-soluble polymers by solid-liquid separation such as filtration. When removing water-soluble polymers by filtration after stirring and mixing the dispersion and solvent, the stirring and filtration may be repeated multiple times to increase the removal efficiency.

[0075] In the third step, the plasticizer may or may not be removed from the dispersion together with the water-soluble polymer. Therefore, the resulting cellulose acylate particles may or may not contain the plasticizer.

[0076] The mixing ratio of the dispersion to the solvent may be 0.01% to 20% by weight of the dispersion, 2% to 15% by weight, or 4% to 13% by weight of the dispersion relative to the total weight of the dispersion and solvent. If the dispersion is greater than 20% by weight, the dissolution of the water-soluble polymer may be insufficient, making it impossible to wash it away. Furthermore, it becomes difficult to separate the cellulose acylate particles that are not dissolved in the solvent from the solvent in which the water-soluble polymer is dissolved by operations such as filtration and centrifugation.

[0077] The mixing temperature of the dispersion and the solvent is preferably between 0°C and 200°C, more preferably between 20°C and 110°C, and even more preferably between 40°C and 80°C. Below 0°C, the solubility of the water-soluble polymer becomes insufficient, making washing and removal difficult. Above 200°C, particle deformation and aggregation occur, making it difficult to extract the particles while maintaining the desired particle shape.

[0078] The mixing time between the dispersion and the solvent is not particularly limited and can be adjusted as appropriate, but for example, it may be 0.5 hours or more, 1 hour or more, 3 hours or more, 5 hours or more, or 6 hours or less.

[0079] The method of mixing the dispersion and the solvent is not particularly limited as long as it can dissolve and remove the water-soluble polymer. For example, by stirring using a stirring device such as an ultrasonic homogenizer or a three-in-one motor, the water-soluble polymer can be efficiently removed from the dispersion even at room temperature.

[0080] For example, when using a three-in-one motor as a stirring device, the rotation speed during mixing of the dispersion and solvent may be, for example, between 5 rpm and 3000 rpm. This allows for more efficient removal of water-soluble polymers from the dispersion. It also allows for more efficient removal of plasticizers from the dispersion.

[0081] In the method for producing the cellulose acylate composition of this disclosure, one or more metal compounds selected from alkali metal compounds and alkaline earth metal compounds are added to the cellulose acylate particles during and / or after the third step. This yields the cellulose acylate composition of this disclosure, which contains metal compound-containing particles that have the effect of acting as a neutralizing agent and an antiblocking agent.

[0082] As alkali metal compounds and alkaline earth metal compounds, the compounds mentioned above as metal compounds included in the cellulose acylate composition can be used individually or in combination of two or more. Hydroxides, oxides, or carbonates of alkali metals or alkaline earth metals are preferred, and calcium carbonate, calcium hydroxide, magnesium carbonate, and magnesium hydroxide are more preferred.

[0083] The amount of metal compound added is preferably 0.01 parts by weight or more and 1.0 part by weight or less per 100 parts by weight of cellulose acylate. From the viewpoint of long-term stability and improved tactile feel, the amount of metal compound added may be 0.02 parts by weight or more, or 0.05 parts by weight or more. From the viewpoint of ensuring that the pH meets the standard, the amount of metal compound added may be 0.8 parts by weight or less, or 0.06 parts by weight or less.

[0084] One method for adding the metal compound after the third step is to add the metal compound to the cellulose acylate particles obtained in the third step and mix them using a mixer such as a ball mill. The metal compound may be added in powder or particulate form, or as a solution or suspension.

[0085] As a method for adding the metal compound during the third step, for example, one could add the metal compound to the solvent used to remove the water-soluble polymer, or one could use a solution containing the metal compound instead of this solvent. In other words, in the third step, the water-soluble polymer is removed and the metal compound is added by washing the dispersion with a solution containing the metal compound.

[0086] In the third step, when the dispersion and solvent are repeatedly stirred, mixed, and filtered to remove the water-soluble polymer, it is preferable to wash with a solution containing a metal compound at least once, and more preferably to wash with a solution containing a metal compound at the end of the step. Considering the effect of removing water-soluble polymers, it is preferable that the solution containing the metal compound is an aqueous solution.

[0087] When the metal compound is added during the third step, a cellulose acylate composition containing metal compound particles with smaller particle sizes is obtained compared to when it is added after the third step. This significantly improves the tactile feel of the resulting cellulose acylate composition. Therefore, the method of adding the metal compound during the third step is more preferable. [Examples]

[0088] The effects of this disclosure will be demonstrated below by the examples, but the technical scope should not be interpreted as being limited based on the description of these examples.

[0089] [Example 1] 100 parts by weight of cellulose diacetate (manufactured by Daicel Corporation: total substitution degree = 2.4) and 22 parts by weight of triacetin (manufactured by Daicel Corporation) as a plasticizer were blended in a dry state and dried at 80°C for 12 hours or more. The mixture was then stirred and mixed using a Henschel mixer (manufactured by Nippon Coke Industries Co., Ltd.) to obtain a mixture of cellulose acetate and plasticizer. The obtained mixture was supplied to a twin-screw extruder (PCM30 manufactured by Ikegai Co., Ltd., cylinder temperature: 200°C, die temperature: 220°C), melt-kneaded, extruded to form pellets, and obtained a kneaded product.

[0090] 34 parts by weight of the resulting compound pellets and 66 parts by weight of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd.: melting point 190°C, degree of saponification 99.1%) as a water-soluble polymer were blended in a dry state, and then supplied to a twin-screw extruder (PCM30 manufactured by Ikegai Co., Ltd., cylinder temperature 220°C, die temperature 220°C) and extruded to form a dispersion.

[0091] The obtained dispersion was mixed with pure water (solvent) to a concentration of 5% by weight or less (weight of dispersion / (weight of dispersion + weight of pure water) × 100), and stirred for 5 hours at 80°C and 200 rpm using a Three One Motor (BL-3000, manufactured by Shinto Kagaku Co., Ltd.). The stirred solution was filtered using filter paper (No. 5A, manufactured by ADVANTEC), and the filtrate was removed. The removed filtrate was again prepared with pure water to a concentration of 5% by weight or less, stirred for 5 hours at 80°C and 200 rpm, filtered, and the filtrate was removed.

[0092] Calcium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in pure water to prepare a 1000 ppm aqueous calcium hydroxide solution. This aqueous calcium hydroxide solution and pure water were added to the extracted filtrate. The amounts of pure water and calcium hydroxide solution added were 600 parts by weight and 15 parts by weight (0.015% by weight as calcium hydroxide) per 100 parts by weight of cellulose diacetate. The filtrate to which pure water and calcium hydroxide solution were added was further put into a three-one motor and stirred at a temperature of 80°C and a rotation speed of 200 rpm for 30 minutes, and then filtered to obtain the cellulose acylate composition of Example 1.

[0093] The cellulose acylate composition obtained in Example 1 was observed with an electron microscope to obtain the image shown in Figure 1. In Figure 1, cellulose acylate particles are indicated by reference numeral 1, and metal compound-containing particles are indicated by reference numeral 2. From Figure 1, it was confirmed that the metal compound-containing particles were aggregates and existed separately from the cellulose acylate particles. Furthermore, elemental analysis using an energy-dispersive X-ray spectrometer (EDS) revealed that the main component of the metal compound-containing particles was calcium carbonate.

[0094] [Examples 2-5, 8 and 10] Cellulose acylate compositions of Examples 2-5, 8, and 10 were obtained in the same manner as in Example 1, except that the types and amounts of additives added to the filtered product were as shown in Tables 1 and 2 below.

[0095] [Example 6] The cellulose acylate composition of Example 6 was obtained in the same manner as in Example 1, except that cellulose acetate propionate (Eastman Chemical Co., Ltd.: CAP-482-0.5, acetyl substitution degree = 0.18, propionyl substitution degree = 2.40) was used instead of cellulose diacetate.

[0096] [Example 7] The cellulose acylate composition of Example 7 was obtained in the same manner as in Example 1, except that cellulose acetate butyrate (Eastman Chemical: CAB-171-15, acetyl substitution degree = 2.40, butyryl substitution degree = 0.71) was used instead of cellulose diacetate.

[0097] [Comparative Example 1] Without adding an aqueous calcium hydroxide solution to the filtered material, the mixture was combined with pure water and stirred using a three-one motor at a temperature of 80°C and a rotation speed of 200 rpm for 5 hours, followed by filtration. This process was repeated three times to obtain the cellulose acylate particles of Comparative Example 1.

[0098] Figure 2 shows an electron microscope image of the cellulose acylate particles obtained in Comparative Example 1. This electron microscope observation confirmed that comparative example 2 did not contain metal compound-containing particles like those indicated by symbol 2 in Figure 1.

[0099] [Example 9] Calcium carbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.: particle size 1-3 μm, average particle size 2 μm) was added to the cellulose acylate particles of Comparative Example 1 in an amount equal to 100 ppm, and the mixture was placed in a ball mill (manufactured by AS ONE Corporation) and rotated for 3 hours on a pot mill turntable (manufactured by Nittokagaku Kogyo Co., Ltd.: AN-3S) to homogenize the cellulose acylate particles and calcium carbonate, thereby obtaining the cellulose acylate composition of Example 9.

[0100] [Physical property measurement and evaluation testing] For the obtained examples and comparative examples, the metal concentration, average particle size, sphericity, and surface smoothness were measured using the methods described below, and the tactile feel, pH immediately after production, pH after storage, and odor were evaluated. The results are shown in Tables 1 and 2.

[0101] [Metal concentration] The metal concentration in each example and comparative example was measured by spectrophotometry. Specifically, 3.0 g of the sample was placed in a crucible, carbonized on an electric heater, and then ashed in an electric furnace at 750-850°C for approximately 2 hours. After covering the crucible and allowing it to cool, 25 ml of 0.07% hydrochloric acid solution was added and heated and dissolved on a hot plate. After cooling, the solution in the crucible was poured into a 200 ml Nalgel flask. After washing the crucible with distilled water, the washing solution was also poured into the Nalgel flask and diluted to the mark with distilled water. Using this as the test solution, the absorbance was measured using an atomic absorption spectrophotometer to determine the metal concentration (ppm) in the sample.

[0102] [Average particle size] For each example and comparative example, the concentration was adjusted to approximately 100 ppm using pure water, and a suspension was prepared using an ultrasonic vibration device. Subsequently, the volume frequency particle size distribution was determined by laser diffraction (using a HORIBA, Ltd. "Laser Diffraction / Scattering Particle Size Distribution Analyzer LA-960", ultrasonic treatment for 15 minutes, refractive index (1.500, medium (water; 1.333))), and the average particle size was measured. The average particle size (nm and μm) was defined as the particle size value corresponding to 50% of the integrated scattering intensity in the volume frequency particle size distribution (volume-based median diameter).

[0103] [Sphericity] Using images of cellulose acylate particles observed with a scanning electron microscope (SEM), the major and minor axes of 30 randomly selected particles were measured, the minor axis / major axis ratio for each particle was determined, and the average of these minor axis / major axis ratios was defined as the sphericity.

[0104] [Surface smoothness] Scanning electron microscope images of cellulose acylate particles from each example and comparative example were taken at 2500 to 5000x magnification. The obtained images were binarized using an image processing device (Winroof, manufactured by Mitani Corporation). From the binarized images, a region including the center and / or vicinity of the center of a single particle was randomly selected, and the area ratio of the concave portion (shaded portion) of the unevenness in that region was calculated. The surface smoothness (%) of that single particle was then calculated using the following formula. Surface smoothness of a single particle (%) = (1 - percentage of concave area) × 100 Area ratio of the concave part = Area of ​​the concave part in the arbitrary region / Area of ​​the arbitrary region The average surface smoothness of 10 randomly selected particle samples (n1 to n10) was defined as the surface smoothness percentage (%). A higher value indicates higher surface smoothness of the particle. The area used to calculate the area percentage may be any area smaller than the particle, including the center and / or vicinity of the center of a single particle. The size of this area may be 5 μm square when the particle diameter is 15 μm.

[0105] [Touch] The tactile sensation of each example and comparative example was evaluated through a panel test involving 20 participants. Each composition was touched, and both smoothness and moistness were evaluated on a scale of 1 to 5. The average score of the 20 participants was calculated, and the tactile sensation was evaluated according to the following criteria. Good: A, Fairly Good: B, Average: C, Fairly Poor: D, Poor: E

[0106] [pH and pH over time] The pH of each example and comparative example immediately after preparation, and the pH after storage in a 60°C constant temperature bath for 90 days (pH over time), were measured using a pH meter (glass electrode method). Specifically, 50 ml of distilled water was measured into a 100 ml conical beaker, and 2.0 g of the sample was added while stirring with a stirrer. After stirring for 30 minutes, the filtrate was collected by pressure filtration. This filtrate was measured using a pH meter.

[0107] [Odor] After storing the compositions of each example and comparative example in a constant temperature bath at 60°C for 90 days, 1.5 g of the sample was taken out with a spatula, smelled, and evaluated according to the following criteria using a 6-level odor intensity scale. 0: Odorless 1: An odor that can finally be detected (detection threshold concentration) 2: A weak odor that can be identified (recognition threshold concentration) 3: Easily detectable odors 4: Strong odor 5: Strong smell

[0108] [Table 1]

[0109] [Table 2]

[0110] As shown in Tables 1 and 2, the compositions of the examples showed a suppressed decrease in pH over time and no odor generation compared to the compositions of the comparative examples. Furthermore, Examples 1-8 and 10, in which alkali metal compounds or alkaline earth metal compounds were added during the third step, were found to have superior tactile properties compared to Example 9, in which the compounds were added after the third step.

[0111] As shown in Table 1-2, the compositions of the examples were evaluated more highly than the compositions of the comparative examples. Furthermore, by incorporating the compositions of the examples, a cosmetic composition with excellent tactile properties could be obtained. These evaluation results clearly demonstrate the advantages of this disclosure. [Industrial applicability]

[0112] The cellulose acylate compositions described above can be applied to the manufacture of various cosmetic compositions. [Explanation of Symbols]

[0113] 1. Cellulose acylate particles 2...metal compound-containing particles

Claims

1. It contains cellulose acylate particles and metal compound-containing particles, The total degree of substitution of the cellulose acylate is 0.7 or more and 2.9 or less. A cellulose acylate composition wherein the metal compound is one or more selected from alkali metal compounds and alkaline earth metal compounds.

2. The cellulose acylate composition according to claim 1, wherein the metal compound is a hydroxide, oxide, or carbonate of an alkali metal or alkaline earth metal.

3. The cellulose acylate composition according to claim 2, wherein the alkali metal is sodium and the alkaline earth metal is calcium or magnesium.

4. The cellulose acylate composition according to any one of claims 1 to 3, wherein the number-average particle diameter of the metal compound-containing particles is 20 nm or more and 20 μm or less.

5. The aforementioned metal compound-containing particles are aggregates, The cellulose acylate composition according to any one of claims 1 to 3, wherein the number-average particle diameter of the aggregates of the metal compound-containing particles is 20 nm or more and 20 μm or less.

6. The cellulose acylate composition according to any one of claims 2 to 5, wherein the alkali metal and alkaline earth metal are contained in a total concentration of 50 ppm or more and 2000 ppm or less.

7. The cellulose acylate composition according to any one of claims 1 to 6, wherein the average particle diameter, which is the median diameter by volume, of the cellulose acylate particles is 80 nm or more and 100 μm or less.

8. The cellulose acylate composition according to any one of claims 1 to 7, wherein the sphericity of the cellulose acylate particles is 0.7 or more and 1.0 or less.

9. The cellulose acylate composition according to any one of claims 1 to 8, wherein the surface smoothness of the cellulose acylate particles is 80% or more and 100% or less.

10. The cellulose acylate composition according to any one of claims 1 to 9, wherein the substituent of the cellulose acylate is an acyl group having 2 to 20 carbon atoms.

11. The cellulose acylate composition according to claim 10, wherein the acyl group is selected from an acetyl group, a propionyl group, and a butyryl group.

12. The cellulose acylate particles contain a plasticizer, The cellulose acylate composition according to any one of claims 1 to 11, wherein the content of the plasticizer is 2% by weight or more and 40% by weight or less with respect to the cellulose acylate particles.

13. The cellulose acylate composition according to claim 12, wherein the plasticizer is one or more selected from the group consisting of citric acid-based plasticizers, glycerin ester-based plasticizers, adipic acid-based plasticizers, and phthalic acid-based plasticizers.

14. A cosmetic composition containing the cellulose acylate composition according to any one of claims 1 to 13.

15. A first step involves mixing a cellulose acylate with a total substitution degree of 0.7 or more and 2.9 or less with a plasticizer to obtain a cellulose acylate impregnated with the plasticizer, A second step involves kneading the cellulose acylate impregnated with the plasticizer and a water-soluble polymer at a temperature of 200°C to 280°C to obtain a dispersion in which the cellulose acylate impregnated with the plasticizer is dispersed. The third step includes removing the water-soluble polymer from the dispersion to obtain cellulose acylate particles, A method for producing a cellulose acylate composition, comprising adding one or more metal compounds selected from alkali metal compounds and alkaline earth metal compounds during and / or after the third step.

16. The manufacturing method according to claim 15, wherein, in the third step, the metal compound is added by washing the dispersion at least once with a solution containing the metal compound.

17. The manufacturing method according to claim 15 or 16, wherein the solution containing the metal compound is an aqueous solution.

18. The manufacturing method according to any one of claims 15 to 17, wherein the amount of the metal compound added to 100 parts by weight of the cellulose acylate is 0.01 parts by weight or more and 1.0 part by weight or less.

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