阅读说明：本技术 含有乙酸纤维素的粒子、化妆品组合物、及含有乙酸纤维素的粒子的制造方法 (Cellulose acetate-containing particle, cosmetic composition, and method for producing cellulose acetate-containing particle ) 是由 小林慧子 大村雅也 于 2019-03-18 设计创作，主要内容包括：本发明的目的在于提供生物分解性、触感及亲油性优异的微粒。本发明的含有乙酸纤维素的粒子的平均粒径为80nm以上且100μm以下、正球度为0.7以上且1.0以下、表面平滑度为80％以上且100％以下、并且对水的表面接触角为100°以上,上述乙酸纤维素的乙酰基总取代度为0.7以上且2.9以下。(The purpose of the present invention is to provide microparticles having excellent biodegradability, tactile sensation, and lipophilicity. The cellulose acetate-containing particles of the present invention have an average particle diameter of 80nm to 100 [ mu ] m, a positive sphericity of 0.7 to 1.0, a surface smoothness of 80% to 100%, and a surface contact angle with water of 100 DEG or more, and the cellulose acetate has a total degree of substitution with acetyl groups of 0.7 to 2.9.)

1. A particle containing cellulose acetate, having an average particle diameter of 80nm to 100 [ mu ] m, a positive sphericity of 0.7 to 1.0, a surface smoothness of 80% to 100%, and a surface contact angle to water of 100 DEG or more,

the cellulose acetate has a total degree of substitution of acetyl groups of 0.7 to 2.9.

2. The particle of claim 1,

the contact angle of the surface of the water is more than 120 degrees.

3. The particle of claim 1 or 2,

the cellulose acetate has a total degree of substitution of acetyl groups of 2.0 or more and less than 2.6.

4. The particle according to any one of claims 1 to 3,

the particles contain a plasticizer in the form of particles,

the plasticizer is contained in an amount of 1 wt% or less with respect to the weight of the particles.

5. The particle of claim 4,

the plasticizer is at least one selected from citric acid plasticizer, glyceride plasticizer, adipic acid plasticizer and phthalic acid plasticizer.

6. The particle of claim 5,

the glyceride plasticizer is glyceryl triacetate.

7. A cosmetic composition comprising the particle according to any one of claims 1 to 6.

8. A method for producing the particles according to claim 1, comprising: a step of surface-treating the cellulose acetate particles with a lipophilicity-imparting agent,

the cellulose acetate particles have an average particle diameter of 80nm to 100 [ mu ] m, a positive sphericity of 0.7 to 1.0, and a surface smoothness of 80 to 100%,

the cellulose acetate has a total degree of substitution of acetyl groups of 0.7 to 2.9.

9. The method for producing particles according to claim 8, wherein,

the lipophilicity imparting agent contains a silicone component.

10. The method for producing particles according to claim 9, wherein,

the surface treatment is a surface treatment by a wet treatment method.

Technical Field

The present invention relates to a cellulose acetate-containing particle, a cosmetic composition, and a method for producing a cellulose acetate-containing particle.

Background

In the past, various kinds of polymer fine particles have been proposed according to the application. For example, the purpose of fine particles contained in cosmetics is also various. The purpose of containing fine particles in cosmetics is: improving the extensibility of the cosmetic; imparting a change to the feel; imparting a wrinkle-lightening effect; and improving smoothness of foundation and the like.

In particular, fine particles having a high sphericity have excellent touch feeling, and can obtain a light scattering (soft focus) effect depending on the physical properties and shape thereof. When such fine particles are used for foundation or the like, effects of filling in the unevenness of the skin to make it smooth and making wrinkles or the like inconspicuous (soft focus) by scattering light in various directions can be expected.

For the purpose and effect of such cosmetics, fine particles having a narrow particle size distribution and a high sphericity are required as fine particles to be blended in the cosmetics, and as such fine particles, fine particles made of polyamide such as nylon 12, or synthetic polymer such as polymethyl methacrylate (PMMA) or Polystyrene (PS) have been proposed.

However, since the fine particles formed of these synthetic polymers have a specific gravity of 1 or less, are light, and have a small particle diameter, they tend to float in water and cannot be removed by a drainage facility, and sometimes they flow into a river directly or further into the sea through a river. Therefore, there is a problem that the sea and the like are contaminated with particles formed of these synthetic polymers.

Further, since the fine particles formed of these synthetic polymers have a property of adsorbing a trace amount of chemical pollutants in the environment, there is a possibility that plankton and fish ingest the fine particles adsorbing the chemical pollutants and may also have adverse effects on the human body, and various effects may be exerted.

In view of such a risk, attempts have been made to replace synthetic polymer fine particles for various uses with particles having biodegradability. In particular, there has been proposed a substitute for cellulose which is a natural component.

In addition, a representative biodegradable resin includes cellulose acetate. Cellulose acetate is excellent in that it can be obtained from natural materials such as wood, cotton, etc. which do not compete with food and feed. It would therefore be beneficial if particles of synthetic polymer could be replaced by particles of cellulose acetate. However, polymers applicable to a method for producing synthetic polymer microparticles are limited, and it is difficult to apply the polymers to the production of cellulose acetate microparticles.

Patent document 1 describes a method including: forming a polysaccharide ester product comprising a polysaccharide ester and a solvent by polysaccharide synthesis; diluting the polysaccharide ester product to obtain a polysaccharide ester coating; and forming a plurality of polysaccharide ester microspheres from the polysaccharide ester coating. Among them, cosmetic compositions are exemplified as articles that can contain polysaccharide ester microspheres.

Patent document 2 describes a cellulose acylate having a volume average particle diameter D50 of 72 μm or more and 100 μm or less, a polymerization degree of 131 or more and 350 or less, and a substitution degree of 2.1 or more and 2.6 or less, which are measured by a laser diffraction particle size distribution measuring apparatus, and a method for producing the cellulose acylate preferably including the following steps: an acylation step of acylating cellulose in the presence of sulfuric acid; and a deacylation step of deacylating the acylated cellulose in a polar solvent in the presence of acetic acid.

Patent document 3 describes that a molded article (for example, a porous body or spherical particles) composed of a resin component (a) is produced by kneading the resin component (a) such as a thermoplastic resin and a water-soluble auxiliary component (B) to prepare a dispersion and eluting the auxiliary component (B) from the dispersion; as the resin component (a), cellulose derivatives such as cellulose acetate are described.

In addition, surface treatment of fine particles has also been proposed in the past. For example, patent document 4 describes the following: in order to provide a powdery cosmetic material which forms a cosmetic film having excellent water resistance and the like, a powder is subjected to a surface treatment so that 90% by weight or more of the total amount of the powder becomes hydrophobic.

Specifically, the following descriptions are included. As for the hydrophobization treatment of the powder, the following methods are generally known: a method of reacting a metal hydroxide with a higher fatty acid on the surface of a powder; coating and sintering the surface of the powder with organic silicon resin; coating the surface of the powder with dimethylpolysiloxane or polymethylhydrogensiloxane, and heating the coated powder or sintering the coated powder with a crosslinking polymerization catalyst as needed; a method of coating the surface of the powder with an alkyl polysiloxane and sintering; uniformly mixing the powder with metal hydroxide or acidic substance to make the polymethylhydrosiloxane generate cross-linking polymerization on the surface of the powder; a method of mechanochemical treatment of the powder with high molecular weight polysiloxane; a method of polymerizing cyclic organosiloxane on the surface of powder in a gas phase at a relatively low temperature; and a method of treating the surface of the powder in an aqueous solution of an organic fluorine compound such as a perfluoroalkyl group-containing phosphoric acid derivative. Examples of the powder include inorganic powders such as titanium oxide and zirconium oxide; resins such as nylon and silicone elastomer; cellulose, silk and other organic powder.

Patent document 5 proposes a microcrystalline cellulose powder characterized by being surface-treated with a metal soap or hydrogenated lecithin. The following are described therein: surface-treating a white powdery cellulose crystallite aggregate having an average degree of polymerization in the range of 75 to 375, which is obtained by subjecting a natural cellulose substance such as cotton, cotton linters (lint), pulp, or the like to acid hydrolysis or alkaline hydrolysis with a metal soap or hydrogenated lecithin. It is described that the ratio (L/D) of the major axis (L) to the minor axis (D) of the fine particles is preferably L/D3 or less.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-500129

Patent document 2: japanese patent No. 6187653

Patent document 3: japanese patent laid-open publication No. 2004-051942

Patent document 4: japanese laid-open patent publication No. 11-222411

Patent document 5: japanese patent laid-open publication No. 2003-146829

Disclosure of Invention

Problems to be solved by the invention

However, the polysaccharide ester microspheres of patent document 1 are porous particles having a large particle diameter and a wide particle size distribution, and are not sufficient as a substitute for synthetic polymer microparticles blended in cosmetics and the like. The cellulose acylate obtained by the production method described in patent document 2 is also porous particles having an irregular shape. The granular molded body obtained by the production method described in patent document 3 is also a granular body having a low spherical shape and a substantially spherical shape. Even if the surface treatment as in patent document 4 is applied to cellulose, a material obtained by pulverizing cellulose tends to have an irregular shape and cannot be in a spherical shape. The fine particles disclosed in patent document 5 have a shape that is far from that of a spherical fine particle, as is clear from the value of the ratio of the major axis (L) to the minor axis (D) of the fine particles.

Although conventional fine particles made of cellulose, cellulose acetate, or the like have excellent biodegradability, cosmetic products having excellent texture cannot be obtained even if the surface is modified to be oleophilic (i.e., hydrophobized) instead of spherical particles.

In addition, in cosmetics, particularly makeup cosmetics, a large amount of an oily component is used for improving water resistance and makeup durability, and conventional biodegradable particles are poor in lipophilicity and therefore poor in dispersibility in the oily component.

The purpose of the present invention is to provide microparticles having excellent biodegradability, tactile sensation, and lipophilicity.

Means for solving the problems

The first aspect of the present invention relates to particles containing cellulose acetate, the particles having an average particle diameter of 80nm or more and 100 μm or less, a positive sphericity of 0.7 or more and 1.0 or less, a surface smoothness of 80% or more and 100% or less, and a surface contact angle with water of 100 ° or more, the cellulose acetate having a total acetyl group substitution degree of 0.7 or more and 2.9 or less.

In the particles, the surface contact angle with water may be 120 ° or more.

In the particle, the cellulose acetate may have a total substitution degree of acetyl groups of 2.0 or more and less than 2.6.

In the particles, the particles may contain a plasticizer, and the content of the plasticizer may be 1% by weight or less based on the weight of the particles.

In the particles, the plasticizer may be at least one selected from the group consisting of a citric acid plasticizer, a glycerin ester plasticizer, an adipic acid plasticizer, and a phthalic acid plasticizer.

In the particles, the glycerin-based plasticizer may be triacetin.

A second aspect of the present invention relates to a cosmetic composition comprising particles.

A third aspect of the present invention relates to a method for producing the above particles, the method comprising: a step of surface-treating the cellulose acetate particles with a lipophilicity-imparting agent,

the cellulose acetate particles have an average particle diameter of 80nm to 100 [ mu ] m, a positive sphericity of 0.7 to 1.0, a surface smoothness of 80% to 100%, and a total degree of substitution of acetyl groups of 0.7 to 2.9.

In the method for producing the particles, the lipophilicity imparting agent may contain a silicone component.

In the method for producing particles, the surface treatment may be a surface treatment by a wet treatment method.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, microparticles having excellent biodegradability, tactile sensation, and lipophilicity can be provided.

Drawings

Fig. 1 is a diagram illustrating a method of evaluating surface smoothness (%).

Fig. 2 is a diagram illustrating a method of evaluating surface smoothness (%).

Fig. 3 is a photograph of a water droplet at the time of contact angle measurement (example 2).

Fig. 4 is a photograph of a water droplet at the time of contact angle measurement (comparative example 2).

Detailed Description

[ particles containing cellulose acetate ]

The cellulose acetate-containing particles of the present invention have an average particle diameter of 80nm to 100 [ mu ] m, a positive sphericity of 0.7 to 1.0, a surface smoothness of 80% to 100%, and a surface contact angle with water of 100 DEG or more, and the cellulose acetate has a total degree of substitution with acetyl groups of 0.7 to 2.9.

When the average particle diameter of the cellulose acetate-containing particles of the present invention is 80nm or more and 100 μm or less, the average particle diameter thereof may be 100nm or more, may be 1 μm or more, may be 2 μm or more, and may be 4 μm or more. The particle size may be 80 μm or less, 40 μm or less, 20 μm or less, 14 μm or less, or 10 μm or less. When the average particle size is too large, the feeling is poor and the light scattering (soft focus) effect is also reduced. In addition, when the average particle size is too small, the production becomes difficult. The feel may be, for example, skin feel or feel when incorporated in a cosmetic composition, in addition to the case where the cellulose acetate-containing particles are directly contacted.

The average particle size can be measured using dynamic light scattering. Specifically, the following is described. First, a sample was prepared by making particles of 100ppm concentration into a pure water suspension using an ultrasonic vibration device. The average particle diameter can be measured by measuring the volume frequency particle size distribution by a laser diffraction method (laser diffraction/scattering particle size distribution measuring device LA-960, manufactured by horiba, Ltd., ultrasonic treatment for 15 minutes, refractive index (1.500, medium (water; 1.333)).

The coefficient of variation of the particle size of the cellulose acetate-containing particles of the present invention may be 0% to 60%, or 2% to 50%.

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

The cellulose acetate-containing particles of the present invention may have a positive sphericity of 0.7 or more and 1.0 or less, preferably 0.8 or more and 1.0 or less, and more preferably 0.9 or more and 1.0 or less. When the amount is less than 0.7, the feeling is poor, and for example, when the composition is blended in a cosmetic composition, the skin feeling and soft focus effect are also reduced.

The sphericity can be determined by the following method. Using an image of the particles observed by a Scanning Electron Microscope (SEM), the major and minor diameters of 30 particles selected at random were measured, and the minor diameter/major diameter ratio of each particle was determined, and the average of the minor diameter/major diameter ratio was defined as the sphericity. The closer to 1 the positive sphericity is, the more the ball can be determined to be positive.

When the surface smoothness of the cellulose acetate-containing particles of the present invention is 80% or more and 100% or less, it is preferably 85% or more and 100% or less, and more preferably 90% or more and 100% or less. When the amount is less than 80%, the feeling is poor. The closer to 100%, the more preferable is the touch feeling.

The surface smoothness can be determined by taking a scanning electron micrograph of the particles, observing the irregularities on the particle surface, and based on the area of the recesses.

The surface contact angle of the cellulose acetate-containing particles of the present invention with water is 100 ° or more, preferably 120 ° or more, and more preferably 130 ° or more. From the viewpoint of affinity with a cosmetic-use oil agent and hydrophobicity, it may be 180 ° or less. When the content is less than 100 degrees, lipophilicity is considered to be insufficient.

The contact angle with respect to the surface of water can be determined by forming a plane with particles (powder), observing a water droplet dropped on the plane, and using the θ/2 method. Specifically, as the measuring device, a fully automatic contact angle measuring instrument (Analysis software: interFAce Measurement and Analysis System FAMAS): manufactured by synechia interfacial science corporation).

The cellulose acetate of the cellulose acetate-containing particles of the present invention has a total degree of substitution of acetyl groups of 0.7 or more and 2.9 or less, preferably 0.7 or more and less than 2.6, more preferably 1.0 or more and less than 2.6, still more preferably 1.4 or more and less than 2.6, and most preferably 2.0 or more and less than 2.6.

When the total substitution degree of acetyl groups is less than 0.7, the water solubility is high, and in a step of producing cellulose acetate particles in the production of cellulose acetate-containing particles described later, particularly in a step of removing a water-soluble polymer from a dispersion, cellulose acetate may be easily eluted, and the sphericity of the particles may be reduced, and therefore, the feel of the cellulose acetate-containing particles may be poor. On the other hand, if it is larger than 2.9, the biodegradability of the cellulose acetate particles is poor.

The total degree of substitution of acetyl groups in cellulose acetate can be determined by the following method. First, the total degree of substitution with acetyl groups means the sum of the degrees of substitution with acetyl groups at the 2,3, and 6 positions of the glucose ring of cellulose acetate, and the degrees of substitution with acetyl groups at the 2,3, and 6 positions of the glucose ring of cellulose acetate can be measured by NMR method according to the method of Otsuka (Tezuka, Carboydr. Res.273,83 (1995)). That is, in pyridine, the free hydroxyl group of a cellulose acetate sample is propionylated with propionic anhydride. The obtained sample was dissolved in deuterated chloroform and measured¹³C-NMR spectrum. The carbon signals of acetyl group appear in the order of 2-, 3-and 6-positions from the high magnetic field in the region of 169ppm to 171ppm, and the signals of carbonyl group carbon of propionyl group appear in the same order in the region of 172ppm to 174 ppm. The substitution degrees of the acetyl groups at the 2,3 and 6 positions of the glucose ring in the original cellulose acetate can be determined from the presence ratio of the acetyl group to the propionyl group at each corresponding position. Except that¹³The degree of substitution with acetyl groups may be determined by C-NMR¹H-NMR.

The total degree of substitution with acetyl groups can be determined by converting the degree of acetylation determined by the method of measurement of the degree of acetylation in ASTM D-817-91 (test method for cellulose acetate, etc.) into the following formula. This is the most common method for calculating the degree of substitution of cellulose acetate.

DS＝162.14×AV×0.01/(60.052－42.037×AV×0.01)

In the above formula, DS is the total degree of substitution of acetyl groups, and AV is the degree of acetylation (%). The value of the degree of substitution obtained by conversion usually has a certain error from the above-mentioned NMR measurement value. When the converted value is different from the NMR measurement value, the NMR measurement value is used. In addition, when the values differ depending on the specific method of NMR measurement, the NMR measurement value based on the above-mentioned manual Iuka method was used.

The outline of the method for measuring the degree of acetylation in ASTM D-817-91 (test method for cellulose acetate and the like) is as follows. First, 1.9g of dried cellulose acetate was accurately weighed and dissolved in 150mL of a mixed solution of acetone and dimethyl sulfoxide (volume ratio: 4:1), 30mL of a 1N-sodium hydroxide aqueous solution was added, and the mixture was saponified at 25 ℃ for 2 hours. Phenolphthalein was added as an indicator and the excess sodium hydroxide was titrated with 1N-sulfuric acid (concentration factor: F). In addition, a blank test was performed in the same manner as described above, and the acetylation degree was calculated according to the following formula.

Average degree of acetylation (%) {6.5 × (B-a) × F }/W

(wherein A represents the titration amount (mL) of 1N-sulfuric acid in the sample, B represents the titration amount (mL) of 1N-sulfuric acid in the blank test, F represents the concentration factor of 1N-sulfuric acid, and W represents the weight of the sample.)

The volume density of the cellulose acetate-containing particles of the present invention may be 0.1 or more and 0.9 or less, and may be 0.5 or more and 0.9 or less. For example, when the particles are blended in a cosmetic, the higher the bulk density of the particles, the better the fluidity of the cosmetic composition. The bulk density can be measured by a method based on JIS K1201-1.

(optional Components)

The cellulose acetate-containing particles of the present invention may or may not contain a plasticizer. In the present invention, the plasticizer is a compound which can increase the plasticity of cellulose acetate. The plasticizer is not particularly limited, and examples thereof include: adipic acid 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, didecyl adipate, and dihexyldecyl adipate; a citric acid plasticizer containing citric acid esters such as acetyl triethyl citrate, acetyl tributyl citrate, isodecyl citrate, isopropyl citrate, triethyl citrate, triethylhexyl citrate, and tributyl citrate; glutaric acid plasticizers containing glutaric acid esters such as diisobutyl glutarate, dioctyl glutarate, and dimethyl glutarate; succinic plasticizers containing succinic acid esters such as diisobutyl succinate, diethyl succinate, diethylhexyl succinate, and dioctyl succinate; sebacic acid plasticizers containing sebacic acid esters such as diisoamyl sebacate, diisooctyl sebacate, diisopropyl sebacate, diethyl sebacate, diethylhexyl sebacate, and dioctyl sebacate; glycerin plasticizers containing glycerin alkyl esters such as triacetin, diacetin, and monoacetin; neopentyl glycol; phthalic acid plasticizers containing phthalic acid esters such as ethyl phthalate, methyl phthalate, diaryl phthalate, diethyl phthalate, diethylhexyl phthalate, dioctyl phthalate, dibutyl phthalate, and dimethyl phthalate; phosphoric acid plasticizers containing phosphoric acid esters such as triolein phosphate, tristearyl phosphate, and trihexadecyl phosphate. Further, di-2-methoxyethyl phthalate, dibutyl tartrate, ethyl benzoylbenzoate, ethyl ethylphthaloyl glycolate (EPEG), ethyl methylphthaloyl glycolate (MPEG), N-ethyltoluene sulfonamide, o-cresol p-toluenesulfonate, triethyl phosphate (TEP), triphenyl phosphate (TPP), glyceryl tripropionate, and the like can be cited. These plasticizers may be used alone, and 2 or more plasticizers may be used in combination.

Among these, preferred are citric acid plasticizers selected from citric acid esters containing triethyl citrate, acetyl tributyl citrate, and the like; glycerin plasticizers containing glycerin alkyl esters such as triacetin, diacetin, and monoacetin; adipic acid plasticizers such as diisononyl adipate; and phthalic acid plasticizers such as ethyl phthalate and methyl phthalate, more preferably at least one selected from triethyl citrate, acetyl tributyl citrate, triacetin and diisononyl adipate, still more preferably at least one selected from acetyl triethyl citrate, triacetin, diacetin and diethyl phthalate, and most preferably triacetin. Among them, phthalic acid plasticizers are concerned about the similarity to environmental hormones, and therefore, attention is required for use.

When the cellulose acetate-containing particles contain a plasticizer, the content of the plasticizer contained in the cellulose acetate-containing particles is not particularly limited. For example, it may be more than 0% by weight relative to the weight of the particles containing cellulose acetate. The content may be 40 wt% or less, 30 wt% or less, 20 wt% or less, 10 wt% or less, 5 wt% or less, or 1 wt% or less.

The content of the plasticizer in the cellulose acetate-containing particles can be controlled by¹H-NMR was measured.

The cellulose acetate-containing particles of the present invention may contain a lipophilicity imparting agent. In the present invention, the lipophilicity imparting agent is a compound capable of adhering to cellulose acetate particles to increase the lipophilicity of the cellulose acetate particles. The attachment to the cellulose acetate particles includes both the case where the particles are attached to or supported on at least a part of the surface of the cellulose acetate particles and the case where the particles are attached so as to cover the entire surface. The expression covering the entire surface of the cellulose acetate particle may be replaced with the covering.

The lipophilicity-imparting agent is preferably coated on the surface of the cellulose acetate particles.

The lipophilicity-imparting agent is not particularly limited, and examples thereof include: lipid components (lipid components including lecithin components), silicone components, metal soap components, fluorine components, amino acid components, ceramide components, and the like. The lipophilicity imparting agent may be contained alone or in combination of two or more.

Among these, the lipophilicity-imparting agent preferably contains glycerophospholipids described later in the lipid component, and lecithin is particularly preferred among the glycerophospholipids. This is because glycerophospholipids, particularly lecithin, are a main component of biological membranes and are highly safe.

The lipophilicity-imparting agent preferably contains a silicone component. The silicone-based component is physiologically inert, highly safe, and stable, and therefore, is suitable for use in the case of cosmetics, particularly those in direct contact with the skin, using particles containing cellulose acetate.

Examples of the lipid component include fats and oils, fatty acid esters, waxes (wax), higher alcohols, phospholipids, and other lipid components. Further, components separated from these lipid components, cured products obtained by hydrogenating these lipid components, and the like are also included in the lipid components.

Examples of the fat or oil include: solid fats and oils such as cacao butter, coconut oil, horse oil, hardened coconut oil, palm oil, beef tallow, mutton tallow, and hardened castor oil.

Examples of the wax include: hydrocarbons such as polyethylene wax, paraffin wax (straight-chain hydrocarbon), microcrystalline wax (branched saturated hydrocarbon), ozokerite, wood wax, montan wax, and fischer-tropsch wax; beeswax, lanolin, carnauba wax, candelilla wax, rice bran wax (rice wax), spermaceti wax, jojoba oil, bran wax (ヌカロウ), montan wax, kapok wax, myrica rubra wax, shellac wax, sugar cane wax, isopropyl lanolate fatty acid, hexyl laurate, reduced lanolin, hard lanolin, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, lanolin fatty acid polyethylene glycol, POE hydrogenated lanolin alcohol ether, and the like.

Examples of the higher alcohol include: higher fatty acids such as myristic acid, palmitic acid, stearic acid, behenic acid, and the like, cetyl alcohol, stearyl alcohol, behenyl alcohol, myristyl alcohol, and cetearyl alcohol, and the like.

Examples of the phospholipid include glycerophospholipids. Among the glycerophospholipids, lecithin refers to a lipid product containing phospholipids, and examples of the lecithin component include soybean lecithin, egg yolk lecithin, and hydrogenated lecithin.

As other lipid components, there may be mentioned: trimethylsiloxy silicic acid, dimethylamino methacrylate quaternary ammonium salt, vinyl pyrrolidone/methacrylic acid-N, N-dimethyl-ethyl ammonioethyl salt copolymer, silicone/polyether urethane resin, (methacryloyloxyethyl carboxybetaine/alkyl methacrylate) copolymer, dextrin, (vinyl pyrrolidone/VA) copolymer, alkyl acrylate copolymer ammonium, polyvinyl alcohol, polyethylacrylate, alkyl acrylate/octylacrylamide) copolymer, acrylate/propyltrimethicone methacrylate copolymer, polyvinyl acetate, acrylate/dimethylsilicone copolymer, and 3- [ tris (trimethylsiloxane) silyl ] propylcarbamate pullulan, and the like.

The silicone component is a component containing a structure represented by the following formula (1) or (2). R in the following formulae (1) and (2) each represents an alkyl group.

[ chemical formula 1]

Examples of the silicone component include: chain silicone oils such as polymethylhydrosiloxane (methylsilicone oil), polydimethylsiloxane (dimethylsilicone oil), hydrogendimethylsilicone oil ((dimethylsilicone oil/methylsilicone oil) copolymer), dimethylsilicone oil-methylphenylsiloxane copolymer, and methylphenylpolysiloxane; cyclic dimethylsiloxanes such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane; cyclic polymethylhydrosiloxane; dimethiconol; silicone components having two or more different reactive groups in the molecule, such as trimethoxyoctylsilane, triethoxyoctylsilane, and aminopropyltriethoxysilane, (alkyl acrylate/dimethylsilicone) copolymers, and graft polymers such as polyether-grafted acrylic siloxane; modified silicone resins such as fluorine-modified silicone resins; and modified silicone oils such as epoxy-modified silicone oil, carboxyl-modified silicone oil, methacrylic-modified silicone oil, alcohol-modified silicone oil, mercapto-modified silicone oil, vinyl-modified silicone oil, amino-modified silicone oil, polyether-modified silicone oil, higher fatty acid-modified silicone oil, and terminal-reactive silicone oil.

Examples of polymethylhydrosiloxane (methylsilicone oil) include: polymethylhydrosiloxane of structural formula (3) below (wherein k is an average number, and k is 7-30).

[ chemical formula 2]

Formula (3)

Examples of the cyclic polymethylhydrosiloxane include cyclic polymethylhydrosiloxanes having a general chemical formula represented by the following formula (4).

[ chemical formula 3]

Formula (4)

Among the silicone-based components, polydimethylsiloxane (dimethylsilicone oil), dimethylsiloxane-methylphenylsiloxane copolymer, and cyclic dimethylsiloxane are preferable.

The metal soap component is a metal salt other than sodium and potassium of a long-chain fatty acid. Specific examples of the metal soap component include: aluminum stearate, magnesium stearate, aluminum myristate, aluminum dimyristate, isopropyl titanium triisostearate, and the like.

The metal soap component has a property of having no solubility in water or equal to that of water but having excellent solubility in an oil component. The metal soap component forms hydrogen bonds with unsubstituted hydroxyl groups of cellulose acetate by the action of the metal. Therefore, the metal soap component has an advantage that the surface treatment can be performed only by supporting the metal soap component. That is, it need not be cured. When a cosmetic composition containing cellulose acetate particles to which lipophilicity has been imparted using a metal soap component is prepared as the lipophilicity imparting agent, the viscosity may be increased particularly in a liquid type cosmetic composition containing a large amount of oil.

The fluorine-based component means a component having a C-F bond (carbon-fluorine bond).

Examples of the fluorine-containing component include: a phosphoric acid derivative having a perfluoroalkyl group, such as a perfluoroalkyl phosphate, an amine salt of a perfluoroalkyl phosphate, a component represented by the following formula (5), and a component represented by the following formula (6); and phosphoric acid derivatives having a perfluoropolyether group. Further, perfluorooctyltriethoxysilane, and perfluoroalkylsilanes such as a component represented by the following formula (7) are exemplified.

[ chemical formula 4]

Formula (5)

In the formula (5), m/n represents 1 to 100, more preferably 20 to 40, a represents 1 to 10, d represents 0 to 2, r represents 1 to 2, and X represents F or CF, respectively₃. In formula (5), the molecular weight of the perfluoropolyether group is preferably 300 or more, more preferably 500 or more.

[ chemical formula 5]

Formula (6)

In the formula (6), n represents an integer of 6 to 18, and m represents 1 or 2.

Formula (7): c_aF_2a+1(CH₂)_bSiX₃

In the formula (7), a represents an integer of 1 to 12, b represents an integer of 1 to 5, and X, which may be the same or different, represents an alkoxy group, a halogen atom, or an alkyl group. Wherein all X's are not included.

Examples of the amine salt of the perfluoroalkyl phosphate ester include commercially available products such as Asahiguard AG530 (manufactured by Asahi glass Co., Ltd.). Examples of the perfluoroalkyl silane include LS-160, LS-360, LS-912, LS-1080, LS-1090, and LS-1465 (manufactured by shin-Etsu chemical Co., Ltd.), and commercially available products such as XC95-418, XC95-466, XC95-467, XC95-468, XC95-469, XC95-470, XC95-471, and XC95-472 (manufactured by Toshiba Silicone Co., Ltd.).

The amino acid component is a component having a structure represented by the following formula (8).

[ chemical formula 6]

Formula (8)

In the formula (8), a saturated or unsaturated aliphatic ester group having 8 to 40 carbon atoms represented by-CR-COOH is bonded to a nitrogen atom of an amino acid represented by a chemical structural formula.

Examples of the amino acid component include: disodium N-stearoyl-L-glutamate, sodium lauroyl aspartate, magnesium palmitoyl glutamate, lauroyl lysine, and caprylyl lysine.

Ceramide is a kind of sphingolipid, and refers to a compound obtained by forming an amide bond between sphingosine and a fatty acid. Examples of the ceramide-like component include "biological ceramide" (human ceramide) cultured in yeast, "natural ceramide" (animal ceramide) derived from animals, "plant ceramide" derived from plants, and "mimic ceramide" (synthetic ceramide) chemically synthesized. The mimic ceramide is sometimes referred to as a synthetic ceramide, or a synthetic mimic ceramide.

Ceramides originally possessed by human skin are composed of seven kinds of "ceramide 1" to "ceramide 7". "ceramide 2" has a high-moisture retention function, and occupies about two components of the ceramide as a whole. Synthetic mimetic ceramides are preferred because of their structure close to that of "ceramide 2". Examples of synthetic mimetic ceramides include: hydroxypropyl dipalmitoamide MEA, and hexadecyloxy PG hydroxyethyl hexadecanamide.

The sphingosine constituting the ceramide may be a synthetic sphingosine analogue, which is a variety of amide derivatives having a structure similar to that of a natural sphingosine derivative. Examples of synthetic sphingosine analogues include: a ceramide analog compound of the following formula (9).

[ chemical formula 7]

Formula (9)

In the above formula (9), R¹R represents a linear or branched saturated or unsaturated alkyl group having 10 to 26 carbon atoms²Represents a linear or branched, saturated or unsaturated alkyl group having 9 to 25 carbon atoms, and X and Y each represent a hydrogen atom or a saccharide residue.

When the cellulose acetate-containing particles contain the lipophilicity imparting agent, the content of the lipophilicity imparting agent contained in the cellulose acetate-containing particles is not particularly limited as long as the lipophilicity imparting agent is locally present on the surface, and may be 0.005% by weight or more, preferably 0.01% by weight or more and 50% by weight or less, more preferably 1% by weight or more and 10% by weight or less, and still more preferably 1.5% by weight or more and 5% by weight or less, relative to the weight of the cellulose acetate-containing particles.

When the amount is less than 0.005% by weight, lipophilicity becomes too low, and when the amount exceeds 50% by weight, aggregation or sticking of particles to each other is likely to occur.

A method for measuring the content of a lipophilic imparting agent in a particle containing cellulose acetate is described. The lipophilic imparting agent containing an element such as silicon which does not constitute cellulose acetate can be obtained by elemental analysis. The lipophilicity-imparting agent present on the surface can be analyzed by a high performance liquid chromatograph or the like by extracting the lipophilicity-imparting agent with an appropriate extraction solvent. In particular, as for the lecithin component, it is preferable to analyze the phospholipid by a high performance liquid chromatograph or the like. These analyses are reported in Dubianguang, Junyang Yiteng, Yazhao, Du Xuan Gao, Chuankou Cheng, Xinbaoxiang, Yuanliang, Wujing Jianfu, jin Zijun, oil chemistry 35, 1018 (1986).

The cellulose acetate-containing particles of the present invention have excellent biodegradability. The rate of biodegradation is preferably 40% by weight or more, more preferably 50% by weight or more within 30 days. May be 80% by weight or less, or may be 60% by weight or less.

The biological decomposition rate can be measured by a method using activated sludge according to JIS K6950.

The cellulose acetate-containing particles of the present invention can be produced by the production method described later.

The cellulose acetate-containing particles of the present invention are excellent in biodegradability, touch and lipophilicity, and therefore can be suitably used in, for example, cosmetic compositions. Further, since the cosmetic composition has a high sphericity, it can provide an effect of filling in the irregularities of the skin to be smooth and making wrinkles inconspicuous (soft focus) by scattering light in various directions when blended in the cosmetic composition. In particular, lipophilicity of particles is important in the formulation of cosmetic preparations. The cosmetic is formed by mixing and dispersing fine particles and an oil agent. In this case, the importance is placed on the degree of fusion (dispersibility) between the fine particles and the oil agent. Even when the particles are formed of cellulose acetate, the stability of the cosmetic composition can be improved by improving the dispersibility in oil when the particles are used in a cosmetic for makeup.

As cosmetic compositions, foundations such as liquid foundations and powder foundations; concealing the concealer; sun protection; isolating; priming lipstick and lipstick; body powder, solid powder, loose powder, and the like: solid powder eye shadow; anti-wrinkle cream; and skin and hair external preparations mainly for cosmetic purposes such as skin care lotions, and the dosage forms thereof are not limited. The dosage form may be aqueous solution, emulsion, suspension, etc.; semisolid agents such as gels and creams; any of solid agents such as powder, granule and solid. In addition, the emulsion can also be in the form of cream, milky lotion, etc.; oil gel formulations such as lipstick; powder formulations such as foundation; and aerosol formulations such as hair styling agents.

[ Process for producing particles containing cellulose acetate ]

The method for producing cellulose acetate-containing particles of the present invention comprises a step of surface-treating cellulose acetate particles with a lipophilicity-imparting agent. The cellulose acetate-containing particles have an average particle diameter of 80nm to 100 [ mu ] m, a positive sphericity of 0.7 to 1.0, a surface smoothness of 80% to 100%, a surface contact angle with water of 100 DEG or more, and a total degree of substitution of acetyl groups of 0.7 to 2.9.

(surface treatment Process)

By surface-treating cellulose acetate particles with a lipophilicity-imparting agent, particles having excellent lipophilicity and excellent dispersibility in oily components can be obtained. The method of surface treatment is not particularly limited as long as the lipophilicity imparting agent can be attached to the surface of the cellulose acetate particles. The attached lipophilicity-imparting agent may be ionically bonded to the cellulose acetate particles, crosslinked, or polymerized.

As a method for attaching the lipophilicity imparting agent to the surface of the cellulose acetate particle, there is a method of simply utilizing physicochemical bonding. Specific examples thereof include the following methods: a method in which cellulose acetate particles are put into a suitable solvent in a state in which a lipophilicity imparting agent is dissolved therein, and the lipophilicity imparting agent is attached to the surfaces of the cellulose acetate particles; a method of attaching a compound having a high polarity or an ionic group to the surface of cellulose acetate particles by ionic bonding using the charge on the surface of the cellulose acetate particles; and a method of attaching a lipophilicity-imparting agent to the surface of cellulose acetate particles by chemically reacting a lipophilicity-imparting agent containing a functional group reactive with a hydroxyl group or the like as a functional group on the surface of cellulose acetate particles to form a chemical covalent bond, for example.

Further, examples of the method include: dry processing, wet processing, spray drying, gas phase, and mechanochemical methods.

The dry treatment method is a method in which a lipophilicity-imparting agent is directly mixed with cellulose acetate particles. When the cellulose acetate particles are present as aggregates formed by aggregating primary particles, the surface of the particles may not be sufficiently coated with the lipophilicity imparting agent by the dry treatment method.

The wet treatment method is a method in which the lipophilicity imparting agent is diluted with an appropriate solvent or dispersion medium, the diluted solution is mixed with cellulose acetate particles, and then the solvent or dispersion medium is evaporated and removed. After evaporation and removal, the oleophilic property-imparting agent may be sintered to the cellulose acetate particles by heat treatment. The solvent can be organic solvent such as ethanol, isopropanol, n-hexane, benzene and toluene. The wet treatment method is more preferable than the dry treatment method in that the lipophilicity imparting agent can be uniformly attached to and coated on the particle surface.

The spray drying method is a method of mixing a lipophilicity imparting agent with a solvent or a dispersion medium to prepare a slurry, spraying the slurry onto cellulose acetate particles, and drying the slurry in a short time to remove the solvent or the dispersion medium. The slurry may be suitably adjusted to a low viscosity to such an extent that it can be sprayed using a solvent or a dispersion medium. The spray drying method is also preferable in that the lipophilicity imparting agent can be uniformly attached to and coated on the particle surface. In the case of spray-drying the slurry at once by the spray-drying method, the particles form aggregates, but the aggregates are broken by the shearing force.

Depending on the kind and concentration of the lipophilicity imparting agent, the lipophilicity imparting agent may act as a binder, and the particles may easily aggregate with each other, resulting in a feeling of being uneven and being hard to touch. In such a case, the wet treatment method is not suitable, and the spray drying method is preferable. Further, the spray drying method is also a very effective method in coating the surface of cellulose acetate particles with microcrystals that are colloidal in water or a compound that is dissolved in water.

In the case where the cellulose acetate of the cellulose acetate particles has a low degree of substitution and is thus water-soluble, the spray drying method is also preferably used.

Examples of the lipophilicity imparting agent include: lipid component, silicone component, metal soap component, fluorine component, amino acid component, lecithin component, ceramide component, etc. One kind of the lipophilicity imparting agent may be used alone, or two or more kinds may be used in combination.

Of these, the lipophilicity imparting agent preferably contains a silicone component. This is because the silicone component is physiologically inactive and relatively stable against various solvents and temperatures, and therefore, wet surface treatment using conditions, solvents, and the like is easily performed, and a function can be easily expressed by adding a small amount of the silicone component.

The case of using a lipid component as a lipophilicity imparting agent will be described in detail. The melting point of the lipid component is preferably 50 ℃ or higher and 80 ℃ or lower, more preferably 60 ℃ or higher and 70 ℃ or lower.

In the case of using an oil or fat as the lipid component, it may be: a melting point of 50 to 70 ℃, a solid fat content of 50 to 100 at 35 ℃, a peroxide value of 0.5 or less, and an iodine value of 0.8 or less. When the melting point is less than 50 ℃, the particles are easily consolidated when the obtained cellulose acetate-containing particles are stored at room temperature. When the temperature exceeds 70 ℃, it is difficult to uniformly coat the cellulose acetate particles. In addition, when the solid fat content at 35 ℃ is less than 50, it is difficult to uniformly coat the cellulose acetate particles. When the peroxide value exceeds 0.5, the particles containing cellulose acetate, which are obtained, are stored at room temperature, and oxidation of the particles is promoted.

The case of using a silicone component as the lipophilicity imparting agent will be described in detail. The kinematic viscosity of the silicone component may be 1 to 1000mm²(cSt) (25 ℃ C.), and may be 20 to 200mm²/s(cSt)(25℃)。

The kinematic viscosity of the silicone-based constituent material was measured by a rheometer.

The boiling point of the silicone component may be 150 ℃ or higher, 180 ℃ or higher, or 200 ℃ or higher. Further, the temperature may be 300 ℃ or lower.

For example, the surface treatment can be performed by adding an appropriate amount of a silicone component to cellulose acetate particles, mixing them, and heating the resulting particles. In particular, when methyl silicone oil, dimethyl silicone oil, and hydrogen dimethyl silicone oil ((dimethyl silicone oil/methyl silicone oil) copolymer) are used as the silicone-based component, the heating may be carried out at a temperature of 105 ℃ for 18 hours.

When a dimethiconol is used as the silicone component, the dimethiconol may be a silicone having hydroxyl groups at both ends of a linear dimethylpolysiloxane skeleton and a molecular weight of 300 to 200000. When the molecular weight is less than 300, the volatility is high, the loss amount in the surface treatment step becomes large, and it is difficult to obtain a product of constant quality. When the molecular weight is more than 200000, the viscosity is high and the reactivity is poor, and the handling is difficult.

Examples of the dimethiconol include materials in the form of oil, dilutions with other silicone oils, and dimethiconol emulsions formed from emulsified compositions with water. The dimethiconol emulsion includes an emulsion obtained by mechanically emulsifying an oil of dimethiconol and an emulsion obtained by emulsion polymerization using a low molecular weight silicone as a starting material. Any type of emulsion can be used as long as the safety of the emulsifier in the emulsification is high. As the dimethiconol, dimethiconol in the form of an emulsion with oil can be suitably used.

The use of a metal soap component as a lipophilicity imparting agent will be described in detail. It is well known that metal soaps are metal salts of long chain hydrocarbon carboxylic acids. The carboxylic acid group is adsorbed to the hydroxyl group remaining on the surface of the cellulose acetate particle and adheres to the particle surface. When a metal soap is used as the lipophilicity imparting agent, the long-chain hydrocarbon group is present on the surface of the particles, and therefore, the dispersibility of the metal soap in an oily component is improved. In addition, the amount of absorption of the oily components of the cellulose acetate particles is also reduced. The amount of oil absorbed is one of the most important factors for powder cosmetic materials in particular. When the amount of the oil component absorbed is large, the surface of the powdery cosmetic material pressed into a cake-like shape is solidified, and a necessary amount cannot be collected at the time of use, and a phenomenon (caking phenomenon) in which use becomes difficult easily occurs. In addition, in the liquid cosmetic composition as well, even if the proportion of the oil component is increased, a uniform state cannot be achieved, or the viscosity becomes too high.

When the surface treatment is performed using isopropyl titanium triisostearate or the like as the metal soap component, it may be referred to as alkyl titanate treatment.

The case of using a fluorine-based component as the lipophilicity imparting agent will be described in detail. By using a perfluoroalkyl phosphate ester as the fluorine-based component, both water repellency and oil repellency can be imparted to the particles containing cellulose acetate. Since the phosphate group is a functional group capable of stably adsorbing an acid, the fluorine-containing component is hardly peeled from the cellulose acetate particle after the surface treatment due to physical factors such as shearing and chemical factors such as solvent and heat.

As one of specific treatment methods for surface-treating the cellulose acetate particles with the fluorine-based component, the following method can be mentioned. For example, a method of adding water to cellulose acetate particles to prepare a slurry, slowly injecting an aqueous solution of a fluorine-based component into the slurry, mixing the slurry, making the slurry acidic, and standing the mixture at normal temperature or high temperature may be mentioned.

For example: a method of dispersing 95 parts by weight of cellulose acetate particles and 5 parts by weight of a fluorine-based component (for example, Asahijguard AG530 (manufactured by Asahi glass Co., Ltd.)) in water, and then heating the resulting system to be acidic.

The surface treatment using the perfluoroalkyl phosphate ester can be performed as follows: a hydrocolloid of perfluoroalkyl phosphate diethanolamine salt is made acidic in the presence of cellulose acetate particles, whereby the hydrocolloid is disintegrated to adsorb perfluoroalkyl phosphoric acid moieties to the particle surface.

By blending cellulose acetate-containing particles having water repellency and oil repellency, a cosmetic composition such as foundation which does not cause removal of makeup on the skin can be obtained. The perfluoroalkyl phosphate ester has oil repellency, but can be dispersed in oil components such as perfluoropolyether.

The case of using an amino acid component as a lipophilicity imparting agent will be described in detail. Dry blending may be utilized. Specific examples thereof include the following methods: cellulose acetate particles were dispersed in a dilute aqueous solution of potassium N-cocoyl glutamate, and then a solution obtained by dissolving N ∈ -lauroyl-L-lysine in an aqueous sodium hydroxide solution of pH13 was mixed with the dispersion, and 1 equivalent of hydrochloric acid was added dropwise under stirring to neutralize the mixture, whereby amino acids were polymerized and precipitated on the surfaces of the cellulose acetate particles.

The case of using a lecithin component as a lipophilicity imparting agent will be described in detail. In particular, the case of using hydrogenated lecithin as the lecithin-based component is exemplified. Cellulose acetate particles are suspended in water to a concentration of about 3 to 30 wt%, and hydrogenated lecithin is added to the cellulose acetate particles in an amount of 1.0 to 30 wt%, and the mixture is stirred sufficiently to homogenize the mixture. Further, an aqueous solution of 1 to 30 wt% of soluble salts of aluminum, magnesium, calcium, zinc, zirconium, titanium, and the like is added dropwise over a period of time such that the amount of the aqueous solution is 0.1 to 2 equivalents relative to the amount of the hydrogenated lecithin. Thus, the hydrogenated lecithin becomes a water-insoluble metal salt, and is completely adsorbed on the surface of the cellulose acetate particle. The cellulose acetate particles treated with the hydrogenated lecithin can be obtained by filtering with a suction filter or the like and drying the obtained cake at 80 to 100 ℃.

The case of using a ceramide-like component as a lipophilicity imparting agent will be described in detail. The method of combining the ceramide-like component and the cellulose acetate particle by a mechanochemical method (dry method), particularly an impact method in a high-velocity air stream, is preferable. The high-speed air flow impact method is a method of treating a ceramide-like component and cellulose acetate particles using a mixer. In the mixer, mechanical heat energy mainly caused by impact force is efficiently transferred to each particle to be combined by the action of the rotor rotating at high speed and the circulation line, and thus composite particles in which cellulose acetate particles are coated with a ceramide-based component can be formed.

Alternatively, a method may be employed in which an oil phase containing ceramide, lauroyl sarcosinate, and hydrogenated phospholipid is emulsified with an aqueous phase to prepare an emulsified composition, the emulsified composition is mixed with cellulose acetate particles, and then the water is dried and removed. The treatment of the particle surface becomes more uniform.

In the oil phase, in addition to the ceramide, the lauroyl sarcosinate, and the hydrogenated phospholipid, for example, as an oil agent generally used in cosmetic materials, an oil agent such as hydrocarbons, oils and fats, waxes, solidified oils, ester oils, fatty acids, higher alcohols, silicone oils, fluorine oils, and lanolin derivatives can be blended without considering the origin of the oil agent such as animal oil, vegetable oil, and synthetic oil, and properties such as solid oil, semisolid oil, liquid oil, and volatile oil.

Specific examples thereof include: hydrocarbons such as liquid paraffin, squalane, vaseline, polyisobutylene, polybutene, paraffin, ceresin, microcrystalline wax, and Fischer-Tropsch wax; oils and fats such as wood wax, olive oil, castor oil, mink oil, and macadamia nut oil; waxes such as montan wax, beeswax, carnauba wax, candelilla wax, and spermaceti wax; esters such as cetyl isooctanoate, isopropyl myristate, isopropyl palmitate, octyldodecyl myristate, glyceryl trioctoate, diglyceryl diisostearate, diglyceryl triisostearate, glyceryl tribehenate, pentaerythritol abietate, neopentyl glycol dicaprylate, cholesterol fatty acid esters, and N-lauroyl-L-glutamic acid di (cholesteryl group/behenyl group/octyldodecyl) ester; fatty acids such as stearic acid, lauric acid, myristic acid, behenic acid, oleic acid, abietic acid, and 12-hydroxystearic acid; higher alcohols such as stearyl alcohol, cetyl alcohol, lauryl alcohol, oleyl alcohol, isostearyl alcohol, behenyl alcohol, and jojoba alcohol; silicones such as low-polymerization degree dimethylpolysiloxane, high-polymerization degree dimethylpolysiloxane, methylphenylpolysiloxane, decamethylcyclopentasiloxane, octamethylcyclotetrasiloxane, and fluorine-modified silicones; fluorine-containing oils such as perfluoropolyether, perfluorodecane and perfluorooctane; lanolin derivatives such as lanolin, lanolin acetate, isopropyl lanolin fatty acid ester, and lanolin alcohol; and so on. These may be used in combination of one kind or two or more kinds.

On the other hand, the aqueous phase may contain, in addition to water as an essential component, polyhydric alcohols such as propylene glycol, dipropylene glycol, and 1, 3-butylene glycol; glycerols such as glycerin and polyglycerin; water-based components such as lower alcohols such as ethanol,

the content of water in the emulsion composition is preferably 70 to 95% by weight, more preferably 80 to 90% by weight. When the amount is within such a range, the emulsified state of the emulsified composition becomes favorable.

(production of cellulose acetate particles)

The manufacturing of the cellulose acetate particles may include: a step for obtaining a cellulose acetate impregnated with a plasticizer by mixing a cellulose acetate having a total degree of substitution with acetyl groups of 0.7 to 2.9 with the plasticizer; a step in which the cellulose acetate impregnated with the plasticizer and a water-soluble polymer are kneaded at 200 ℃ to 280 ℃ to obtain a dispersion in which the cellulose acetate impregnated with the plasticizer is a dispersoid; and a step of removing the water-soluble polymer from the dispersion.

(Process for obtaining cellulose acetate impregnated with plasticizer)

In the step of obtaining a plasticizer-impregnated cellulose acetate, a cellulose acetate having a total degree of substitution of acetyl groups of 0.7 or more and 2.9 or less is mixed with a plasticizer.

Cellulose acetate having a total degree of substitution of acetyl groups of 0.7 or more and 2.9 or less can be produced by a known method for producing cellulose acetate. As such a production method, there is a so-called acetic acid method using acetic anhydride as an acetylating agent, acetic acid as a diluent, and sulfuric acid as a catalyst. The basic steps of the acetic acid process include the following steps: (1) a pretreatment step of dissociating/pulverizing a pulp raw material (dissolving pulp) having a high alpha-cellulose content and then spraying mixed acetic acid; (2) an acetylation step of reacting the pretreated pulp of (1) with a mixed acid containing acetic anhydride, acetic acid and an acetylation catalyst (e.g., sulfuric acid); (3) a ripening step of hydrolyzing cellulose acetate to produce cellulose acetate having a desired degree of acetylation; and (4) a post-treatment step of precipitating and separating the cellulose acetate from the reaction solution after the hydrolysis reaction is completed, purifying, stabilizing and drying the cellulose acetate.

The cellulose acetate preferably has a total degree of substitution of acetyl groups of 0.7 or more and 2.9 or less, 0.7 or more and less than 2.6, more preferably 1.0 or more and less than 2.6, still more preferably 1.4 or more and less than 2.6, and most preferably 2.0 or more and less than 2.6. The total substitution degree of acetyl groups can be adjusted by adjusting the conditions (such as time and temperature) of the aging step.

The plasticizer is not particularly limited as long as it has a plasticizing effect in melt extrusion processing of cellulose acetate, and specifically, the above-mentioned plasticizers exemplified as the plasticizer contained in the cellulose acetate particles may be used alone or in combination of 2 or more kinds of plasticizers.

Among the plasticizers described as examples, preferred are citric acid plasticizers selected from the group consisting of triethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate; glycerin plasticizers containing glycerin alkyl esters such as triacetin, diacetin, and monoacetin; adipic acid plasticizers such as diisononyl adipate; and at least one or more phthalic acid plasticizers such as ethyl phthalate and methyl phthalate, more preferably at least one or more plasticizers selected from triethyl citrate, acetyl tributyl citrate, triacetin and diisononyl adipate, and still more preferably at least one or more plasticizers selected from acetyl triethyl citrate, triacetin, diacetin and diethyl phthalate. Among them, phthalic acid plasticizers are concerned about the similarity to environmental hormones, and therefore, attention is required for use.

The amount of the plasticizer to be blended may be more than 0 part 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, and 15 parts by weight or more and 20 parts by weight or less, based on 100 parts by weight of the total amount of the cellulose acetate and the plasticizer. If the amount is too small, the regular sphericity of the obtained cellulose acetate particles tends to decrease, and if the amount is too large, the shape of the particles cannot be maintained, and the regular sphericity tends to decrease.

The mixing of the cellulose acetate and the plasticizer may be carried out in a dry or wet manner using a mixer such as a henschel mixer. When a mixer such as a Henschel mixer is used, the temperature in the mixer may be a temperature at which the cellulose acetate does not melt, for example, a temperature in the range of 20 ℃ or more and less than 200 ℃.

The mixing of the cellulose acetate and the plasticizer may be carried out by melt kneading. In this case, it is preferable to perform melt kneading after mixing at a temperature condition of 20 ℃ or higher and less than 200 ℃ using a mixer such as a henschel mixer. By fusing the plasticizer and the cellulose acetate more uniformly and in a short time, the particle containing cellulose acetate finally produced can have a high degree of sphericity, and can have a good touch and touch comfort.

The melt kneading is preferably performed by heating and mixing using an extruder. The mixing temperature (cylinder temperature) of the extruder may be in the range of 200 to 230 ℃. Even at a temperature within this range, the resulting mixture can be plasticized to obtain a uniform kneaded product. When the temperature is too low, the positive sphericity of the obtained particles is reduced, and therefore, the feeling and the touch comfort are reduced, and when the temperature is too high, the kneaded product may be thermally deteriorated or colored. In addition, the viscosity of the melt may decrease, and the kneading of the resin in the twin-screw extruder may be insufficient.

This is because the melting point of cellulose acetate is generally 230 to 280 ℃ and close to the decomposition temperature of cellulose acetate, although it depends on the degree of substitution, and therefore it is generally difficult to melt-knead the cellulose acetate in this temperature range, but the plasticizing temperature of cellulose acetate (sheet) impregnated with a plasticizer can be lowered. The kneading temperature (cylinder temperature) may be, for example, 200 ℃ in the case of using a twin-screw extruder. The kneaded product is extruded in a strand-like form and then pelletized by hot cutting or the like. The mold temperature in this case may be about 220 ℃.

(step of obtaining Dispersion)

In the step of obtaining the dispersion, the cellulose acetate impregnated with the plasticizer and the water-soluble polymer are kneaded at 200 ℃ to 280 ℃.

The cellulose acetate impregnated with the plasticizer and the water-soluble polymer can be kneaded by using an extruder such as a twin-screw extruder. The kneading temperature is the cylinder temperature.

The dispersion may be cut into pellets after being extruded in a string form from a die attached to the tip of an extruder such as a twin-screw extruder. In this case, the mold temperature may be 220 ℃ or higher and 300 ℃ or lower.

The amount of the water-soluble polymer blended 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 the cellulose acetate impregnated with the plasticizer and the water-soluble polymer. Preferably 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.

The water-soluble polymer in the present specification means a polymer having an insoluble content of less than 50% by weight when 1g of the polymer is dissolved in 100g of water at 25 ℃. Examples of the water-soluble polymer include: polyvinyl alcohol, polyethylene glycol, sodium polyacrylate, polyvinyl pyrrolidone, polypropylene oxide, polyglycerol, polyethylene oxide, vinyl acetate, modified starch, thermoplastic starch, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and the like. Among these, polyvinyl alcohol, polyethylene glycol and thermoplastic starch are preferable, and polyvinyl alcohol and thermoplastic starch are particularly preferable. The thermoplastic starch may be obtained by a known method. For example, Japanese examined patent publication (Kokoku) No. 6-6307 and WO92/04408 can be cited, and more specifically, for example, a thermoplastic starch obtained by mixing tapioca starch with about 20% of glycerin as a plasticizer and kneading the mixture with a twin-screw extruder can be used.

The obtained dispersion was a dispersion in which a water-soluble polymer was used as a dispersion medium and cellulose acetate impregnated with the plasticizer was used as a dispersoid. In other words, the sea component may be a water-soluble polymer and the island component may be cellulose acetate impregnated with the plasticizer. In the dispersion, the kneaded material constituting the island component contains cellulose acetate and a plasticizer, and is mainly spherical.

(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, and for example, water; alcohols such as methanol, ethanol, and isopropanol; or a mixed solution thereof, and removing the water-soluble polymer of the dispersion by dissolving it in a solvent. Specifically, for example, a method of removing the water-soluble polymer from the dispersion by mixing the dispersion with the solvent, filtering the mixture, and then taking out the filtrate is exemplified.

In the step of removing the water-soluble polymer from the dispersion, the plasticizer may be removed from the dispersion together with the water-soluble polymer, or the plasticizer may not be removed. Therefore, the obtained cellulose acetate particles may or may not contain a plasticizer.

The mixing ratio of the dispersion and the solvent is preferably 0.01 wt% or more and 20 wt% or less, more preferably 2 wt% or more and 15 wt% or less, and further preferably 4 wt% or more and 13 wt% or less, based on the total weight of the dispersion and the solvent. When the amount of the dispersion is more than 20% by weight, the dissolution of the water-soluble polymer becomes insufficient and the water-soluble polymer cannot be removed by washing, and it is difficult to separate the cellulose acetate particles which are not dissolved in the solvent from the water-soluble polymer dissolved in the solvent by filtration, centrifugation or the like.

The mixing temperature of the dispersion and the solvent is preferably 0 ℃ to 200 ℃, more preferably 20 ℃ to 110 ℃, and still more preferably 40 ℃ to 80 ℃. If the temperature is lower than 0 ℃, the solubility of the water-soluble polymer becomes insufficient and the removal by washing becomes difficult, and if the temperature exceeds 200 ℃, deformation, aggregation, and the like of the particles occur, and it becomes difficult to take out the particles while maintaining a desired particle shape.

The mixing time of the dispersion and the solvent is not particularly limited, and may be, for example, 0.5 hours or more, 1 hour or more, 3 hours or more, 5 hours or more, or 6 hours or less.

The method of mixing is not limited as long as the water-soluble polymer can be dissolved, and the water-soluble polymer can be efficiently removed from the dispersion even at room temperature by using a stirring device such as an ultrasonic homogenizer or a Three-in-One Motor (Three-One Motor).

For example, when a three-in-one motor is used as the stirring device, the rotation speed at the time of mixing the dispersion and the solvent may be, for example, 5rpm or more and 3000rpm or less. This enables the water-soluble polymer to be more efficiently removed from the dispersion. In addition, the plasticizer can be efficiently removed from the dispersion.

Examples

The present invention will be described in more detail with reference to examples, but the technical scope of the present invention is not limited to these examples.

(example 1)

Production of cellulose acetate particles

100 parts by weight of cellulose diacetate (manufactured by Daiiol corporation: total degree of substitution of acetyl DS: 2.4) and 25 parts by weight of glyceryl triacetate as a plasticizer were blended in a dry state, dried at 80 ℃ for 12 hours or more, and further stirred and mixed by a Henschel mixer to obtain a mixture of cellulose acetate and a plasticizer. The obtained mixture was fed to a twin-screw extruder (PCM 30, cylinder temperature: 200 ℃ C., die temperature: 220 ℃ C., manufactured by Kyowa Kagaku Co., Ltd.), melt-kneaded and extruded, and pelletized to obtain a kneaded product.

32 parts by weight of the pellets of the resulting kneaded product and 68 parts by weight of polyvinyl alcohol (manufactured by Nippon Chemicals: melting point 190 ℃ C., degree of saponification: 99.1%) as a water-soluble polymer were blended in a dry state, and then fed to a twin-screw extruder (PCM 30 manufactured by Chikusho Seisakusho, Ltd., cylinder temperature 220 ℃ C., die temperature 220 ℃ C.) and extruded to form a dispersion.

The obtained dispersion was combined with pure water (solvent) so as to be 5% by weight or less (weight of dispersion/(weight of dispersion + weight of pure water) × 100), and stirred at 80 ℃ and 500rpm for 5 hours using a three-in-one motor (BL-3000, manufactured by shin-chan scientific). The stirred solution was filtered through a filter paper (product No.5A, ADVANTEC), and the filtrate was taken out. The filtrate was prepared again using pure water so that the dispersion became 5 wt% or less, and further stirred at 80 ℃ and 500rpm for 3 hours, filtered, and the filtrate was taken out, and this operation was repeated 3 times or more to obtain cellulose acetate particles.

Surface treatment of cellulose acetate particles

Into a 5000ml separable flask were charged 900g of n-hexane (Mw: 86.2) and 12g of KF-9901 (hydrogen dimethicone: manufactured by shin-Etsu chemical Co., Ltd.), and the mixture was dissolved by stirring at room temperature. 600g of the obtained cellulose acetate particles were further charged, and stirring was continued at room temperature for 30 minutes to disperse the cellulose acetate particles, thereby preparing a slurry. The slurry was distilled in a water bath at 85 ℃ under normal pressure to remove n-hexane. This makes the entire system particulate. Then, the surface of the cellulose acetate particles was sintered with dimethylsilicone oil by stirring at 120 ℃ for 2 hours or more, thereby obtaining surface-treated cellulose acetate particles.

The average particle diameter, the coefficient of variation in particle diameter, the sphericity, the surface smoothness, the bulk density, the plasticizer content, the biodegradability, the feel, the degree of floating in water, the degree of floating in isododecane, and the contact angle of the particles after surface treatment of cellulose acetate were measured and evaluated. Further, the biodegradability and the feel of cellulose acetate particles were also measured and evaluated. The results are shown in Table 1. The measurement or evaluation of each physical property was performed by the following method.

< average particle diameter and coefficient of variation of particle diameter >

The average particle size was measured by dynamic light scattering. First, a sample was adjusted to a concentration of about 100ppm using pure water, and a pure water suspension was prepared using an ultrasonic vibration device. Then, a volume frequency particle size distribution was obtained by ultrasonic treatment for 15 minutes by a laser diffraction method (laser diffraction/scattering particle size distribution measuring device LA-960, manufactured by horiba, Ltd., refractive index (1.500, medium (water; 1.333)) to measure an average particle size, the average particle size (nm, μm, etc.) described herein means a particle size value corresponding to a cumulative 50% of scattering intensity in the volume frequency particle size distribution, and a particle size variation coefficient (%) was calculated by a standard deviation of particle size/average particle size × 100.

< sphericity of sphericity >

Using an image of the particles observed by a Scanning Electron Microscope (SEM), the major and minor diameters of 30 particles selected at random were measured, and the minor diameter/major diameter ratio of each particle was determined, and the average of the minor diameter/major diameter ratio was defined as the sphericity.

< surface smoothness >

A scanning electron micrograph of the particles was taken at a magnification of 2500 to 5000 (see fig. 1 for an example of a micrograph of the cellulose acetate particles), and the image was binarized using an image processing apparatus Winroof (manufactured by mitsubishi corporation) (see fig. 2 for an image obtained by binarizing the micrograph of fig. 1). May be any region including the center of 1 particle and/or smaller than the particle near the center (for example, regions denoted by n1 and n2 if referring to fig. 2). When the particle size is 15 μm, the size of the region may be 5 μm square. The area ratio of concave portions (negative portions) corresponding to the concavities and convexities in the region was calculated, and the surface smoothness (%) of 1 particle was calculated by the following equation.

Surface smoothness (%) of 1 particle (1-concave area ratio) × 100

The ratio of the area of the recess to the area of the recess in the arbitrary region/the arbitrary region

The surface smoothness (%) is an average value of the surface smoothness of 10 randomly selected particle samples, i.e., n1 to 10. The higher the value, the higher the surface smoothness.

< bulk density >

Measured according to "JIS K1201-1".

< plasticizer content >

By passing¹H-NMR measurement the plasticizer content (% by weight) was measured.

< biodegradability >

Biodegradability was evaluated based on the rate of biodegradation. The biodegradation rate was measured by a method using activated sludge based on JISK 6950. Activated sludge is obtained from municipal sewage treatment plants. About 300mL of supernatant (activated sludge concentration: about 360ppm) obtained by leaving the activated sludge for about 1 hour was used per 1 flask. The time when 30mg of the sample was stirred in the supernatant was set as the start of the measurement, and the measurement was performed every 24 hours until a total of 31 measurements were performed after 720 hours, that is, 30 days. The details of the measurement are as follows. The Biochemical Oxygen Demand (BOD) in each culture flask was measured using an electricity meter OM3001 manufactured by electrical warehouse corporation. The biodegradability was evaluated as follows, taking the percentage of Biochemical Oxygen Demand (BOD) relative to the theoretical BOD at the time of complete decomposition obtained based on the chemical composition of each sample as the biological decomposition rate (wt%).

Very good: more than 60% by weight

O: 40 to 60 wt.% of

And (delta): 10 to less than 40% by weight

X: less than 10% by weight

< touch feeling >

Sensory evaluation was performed by a panel test of 20 persons for the tactile sensation of the particles. The touch particles were fully divided by 5, and both the smoothness and the feeling of smoothness were evaluated comprehensively according to the following criteria. The average score of 20 persons was calculated.

Good: 5; slightly better: 4; the method comprises the following steps: 3; slightly worse: 2; difference: 1

Degree of floatation in water

The particles 1g and water 50mL in the rotation speed of 100rpm above and time of 30 seconds above conditions of mixing stirring, standing for more than 30 seconds, collecting floating in the water particles and drying, the weight of the measurement. The weight of the particles floating in water after drying, where the weight of the particles before mixing and stirring with water was 100, was defined as the degree of floating in water.

(degree of floatation in isododecane) >

1g of the particles and 50mL of isododecane were mixed and stirred at a rotation speed of 100rpm or more for 30 seconds or more, and then left to stand for 30 seconds or more, and the particles floating in isododecane were collected and dried, and then the weight thereof was measured. The weight of particles floating in isododecane after drying, where the weight of particles before mixing and stirring with isododecane was taken as 100, was taken as the isododecane floating degree.

< surface contact Angle to Water (θ/2 method) >

A double-sided tape was attached to the cut sheet (prapiarat), and 2g of particles were uniformly applied to the sheet to form a flat surface, and a water droplet was dropped on the flat surface to obtain a contact angle of the water droplet by the θ/2 method. The apparatus used for dropping a water droplet and measuring a contact angle was a fully automatic contact angle measuring instrument (Analysis software: interFAce Measurement and Analysis System FAMAS): manufactured by synechia interfacial science corporation).

(example 2)

Production of cellulose acetate particles

Cellulose acetate particles were obtained in the same manner as in example 1, except that a kneaded material was obtained in the same manner as in example 1 except that triacetin was changed to 22 parts by weight, particles of the obtained kneaded material were changed to 34 parts by weight, and polyvinyl alcohol was changed to 66 parts by weight, a dispersion was formed in the same manner as in example 1, the obtained dispersion was combined with pure water so that the weight% of the dispersion was 5% or less, and the mixture was stirred at a temperature of 80 ℃ and a rotation speed of 200rpm for 5 hours.

Surface treatment of cellulose acetate particles

The obtained cellulose acetate particles were subjected to surface treatment in the same manner as in example 1.

The obtained cellulose acetate particles and the surface-treated cellulose acetate particles were subjected to the measurement and evaluation of the physical properties in the same manner as in example 1, respectively, by the methods described above. The results are shown in table 1 and fig. 3.

(example 3)

Production of cellulose acetate particles

Cellulose acetate particles were obtained in the same manner as in example 1, except that 100 parts by weight of a component obtained by mixing 80 parts by weight of thermoplastic starch (manufactured by Sanko starch industries Ltd.: pregelatinized tapioca starch) with 20 parts by weight of glycerin was used as the water-soluble polymer in place of the polyvinyl alcohol to form a dispersion, and 68 parts by weight of the dispersion was used.

Surface treatment of cellulose acetate particles

The obtained cellulose acetate particles were subjected to surface treatment in the same manner as in example 1.

The obtained cellulose acetate particles and the surface-treated cellulose acetate particles were subjected to the measurement and evaluation of the physical properties in the same manner as in example 1, respectively, by the methods described above. The results are shown in Table 1.

Comparative examples 1 to 3

Cellulose acetate particles were obtained in the same manner as in examples 1 to 3, but the surface treatment of the cellulose acetate particles was not performed. The obtained cellulose acetate particles were subjected to measurement and evaluation of physical properties by the methods described above. The results are shown in table 1 and fig. 4.

[ Table 1]

As shown in table 1, it can be seen that: the particles of the examples had excellent biodegradability and touch comparable to those of the particles of the comparative examples. Further, as shown in table 1 and fig. 4, the particles of the comparative examples were all immersed in water, and the surface contact angle with water was also 80 to 92 °, and all of the particles were immersed in water. On the other hand, the particles of the examples were all floating in water, and the contact angle with water was a value far exceeding 100 °, and all of them were sunk in isododecane. From this, it is understood that the particles of the examples have excellent lipophilicity.