JP6168401B2 - Polylactic acid resin fine particles, dispersion using the same, and method for producing polylactic acid resin fine particles - Google Patents

Description

  The present invention relates to polylactic acid resin fine particles, a dispersion using the same, and a method for producing polylactic acid resin fine particles, and more particularly to polylactic acid resin fine particles having a number average particle diameter of less than 1 μm.

  Unlike polymer molded products such as films, fibers, injection molded products, and extrusion molded products, polymer fine particles are used to modify and improve various materials by utilizing the large specific surface area and the structure of fine particles. ing. Major applications include cosmetic modifiers, toner additives, rheology modifiers such as paints, medical diagnostic inspection agents, additives to molded articles such as automotive materials and building materials.

  On the other hand, with increasing interest in environmental issues in recent years, it has been required to use materials derived from non-petroleum raw materials for the purpose of reducing environmental impact, and polymer fine particles such as cosmetics and paints are used. The field is no exception. A typical example of these non-petroleum raw material-derived polymers is polylactic acid.

  So far, polylactic acid-based resin fine particles or powders are produced by pulverization methods such as freeze pulverization (Patent Documents 1 and 2), dissolved in a solvent at high temperature, cooled and precipitated, or dissolved in a solvent. And then adding a poor solvent to the solvent solution precipitation method (Patent Documents 3 and 4), mixing a polylactic acid resin and an incompatible resin in a mixer such as a twin screw extruder, Melt to obtain polylactic acid resin fine particles by forming a resin composition that has a resin phase in the dispersed phase and a resin phase incompatible with the polylactic acid resin in the continuous phase, and then removing the incompatible resin. A kneading method (Patent Documents 5 and 6) is known.

  However, the polylactic acid-based resin fine particles produced by these manufacturing methods can maintain a spherical shape such that the obtained particles are not spherical, the particle diameter does not become fine, the particle size distribution is wide, and in some cases includes fibrous substances. In particular, in the cosmetics field where emphasis is placed on tactile sensation and texture, and in the field of paints where rheology control is important, the effect of adding fine particles is not sufficient as it is.

  On the other hand, as a method for producing polymer fine particles, a method described in Patent Document 7 is known as a method using an emulsion. Patent Document 8 describes a method for producing polylactic acid resin fine particles. However, these documents do not describe production examples of polylactic acid resin fine particles having a number average particle diameter of less than 1 μm.

JP 2000-007789 A JP 2001-288273 A JP 2005-002302 A JP 2009-242728 A JP 2004-269865 A Japanese Patent Laid-Open No. 2005-200663 International Publication No. 2009/142231 International Publication No. 2012/105140

  The present invention is a method for producing polylactic acid resin fine particles having a number average particle diameter of less than 1 μm, and suitable for cosmetic applications and the like. Offering is an issue.

As a result of intensive studies by the present inventors in order to achieve the above object, the following invention has been achieved.
That is, the polylactic acid-based resin fine particles according to the present invention, the dispersion using the same, and the method for producing the polylactic acid-based resin fine particles have the following configurations.

[1] A polylactic acid resin fine particle having a number average particle diameter of 10 nm or more and less than 1 μm.

[2] The polylactic acid-based resin fine particles according to [1], wherein the particle size distribution index is 1 to 2.

[3] The polylactic acid resin fine particles according to the above [1] or [2], wherein the sphericity is 90 or more.

[4] A dispersion obtained by dispersing the polylactic acid resin fine particles according to any one of [1] to [3] above.

[5] A polylactic acid-based resin (A) and a polymer (B) different from the polylactic acid-based resin are dissolved in an ether-based organic solvent (C), and a solution phase containing the polylactic acid-based resin (A) as a main component and poly A dissolution step for forming a system for phase separation into two phases of a solution phase mainly comprising a polymer (B) different from a lactic acid resin, an emulsion formation step for stirring the phase separation system to form an emulsion, A particle precipitation step of depositing polylactic acid resin fine particles by bringing the poor solvent (α) of the polylactic acid resin in which the solubility of the lactic acid resin (A) is smaller than that of the ether organic solvent (C) into contact with the emulsion. A method for producing polylactic acid resin fine particles, wherein the particle precipitation step is performed by adding a polylactic acid resin to a poor solvent (α) to the emulsion or adding the emulsion to a poor solvent (α) of the polylactic acid resin. An addition step for bringing the poor solvent (α) of the polylactic acid resin into contact with the emulsion, and a contact step for precipitating the polylactic acid resin fine particles by maintaining the contact state between the poor solvent (α) of the polylactic acid resin and the emulsion. The mass ratio (A / B) of the polymer (B) that is different from the polylactic acid resin (A) and the polylactic acid resin is 0.8 or less, and the stirring power at the time of forming the emulsion is 0. A method for producing polylactic acid-based resin fine particles, which is 01 kW / m ³ or more, and the time required for the addition step is 10 minutes or more and 90 minutes or less.

[6] The method for producing polylactic acid resin fine particles according to [5] above, wherein the boiling point of the ether organic solvent (C) is 100 ° C. or higher.

[7] The method for producing polylactic acid resin fine particles according to [6], wherein the ether organic solvent (C) is diethylene glycol dimethyl ether.

[8] The method for producing polylactic acid resin fine particles according to any one of [5] to [7], wherein the polymer (B) different from the polylactic acid resin is hydroxypropyl cellulose.

[9] The method for producing fine polylactic acid resin particles according to any one of [5] to [8], wherein the poor solvent (α) of the polylactic acid resin is water.

  According to the method for producing polylactic acid-based resin particles according to the present invention, it is possible to easily produce polylactic acid-based resin particles having a size of less than 1 μm, and more effective biodegradability can be obtained. Furthermore, it becomes possible to produce polylactic acid resin fine particles having a desired form according to the application, such as true spherical polylactic acid resin fine particles having good sliding properties. Further, the polylactic acid resin fine particles obtained by the present invention are used for cosmetic materials such as foundations, lipsticks, and scrubs for male cosmetics, flash molding materials, rapid prototyping / rapid manufacturing materials, and plastic sol pastes. Resin, powder blocking material, powder fluidity improver, lubricant, rubber compounding agent, abrasive, thickener, filter agent and filter aid, gelling agent, flocculant, paint additive, oil absorbing agent, Mold release agents, plastic film / sheet slipperiness improvers, antiblocking agents, gloss modifiers, matte finish agents, light diffusing agents, surface high hardness improvers, toughness improvers, and other modifiers, for liquid crystal display devices Spacers, chromatography fillers, cosmetic foundation materials and additives, microcapsule aids, drug delivery systems For medical materials such as system and diagnostic agents, perfume and agrochemical retention agents, chemical reaction catalysts and carriers, gas adsorbents, sintered materials for ceramic processing, standard particles for measurement and analysis, for the food industry It can be suitably used for particles, powder coating materials, electrophotographic developing toners, and the like.

1 is an observation view of polylactic acid resin fine particles produced in Example 1 with a scanning electron microscope. FIG. FIG. 6 is an observation view of polylactic acid resin fine particles produced in Example 5 with a scanning electron microscope. FIG. 10 is an observation view of polylactic acid resin fine particles produced in Comparative Example 5 with a scanning electron microscope.

Hereinafter, the present invention will be described in detail.
The method for producing the polylactic acid-based resin fine particles in the present invention comprises dissolving a polylactic acid-based resin (A) and a polymer (B) different from the polylactic acid-based resin in an ether-based organic solvent (C), and mainly using the polylactic acid-based resin. An emulsion that forms an emulsion by stirring the phase-separating system and a dissolving process that forms a phase-separating system into two phases, a solution phase mainly composed of a polymer B different from a polylactic acid resin, A forming step and a particle precipitation step of depositing polylactic acid resin fine particles by bringing the emulsion into contact with a poor solvent (α) of the polylactic acid resin.

  The method for producing the polylactic acid resin fine particles is characterized in that the organic solvent used is an ether organic solvent (C). By using the ether organic solvent (C), it is possible to prevent fusion of the polylactic acid resin fine particles generated when the poor solvent (α) of the polylactic acid resin is contacted. Organic solvents other than the ether organic solvent (C), for example, ester solvents such as methyl acetate and ethyl acetate, chloroform, bromoform, methylene chloride, 1,2-dichloroethane, 1,1,1-trichloroethane, chlorobenzene, 2, Halogenated hydrocarbon solvents such as 6-dichlorotoluene, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl butyl ketone, acetal solvents such as dimethyl acetal, diethyl acetal, dipropyl acetal, dioxolane, N-methyl 2-pyrrolidone, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, propylene carbonate, trimethyl phosphoric acid, 1,3-dimethyl-2-imidazolidinone, sulfolane, acetonitrile, etc. When a carboxylic acid solvent such as protic polar solvent, formic acid, acetic acid, propionic acid, butyric acid, lactic acid is used, the polylactic acid resin dissolves well, so the precipitation ability of the polylactic acid resin is not sufficient. It is difficult to form and when the poor solvent (α) of the polylactic acid resin is contacted, the solvent remains inside the precipitated polylactic acid resin fine particles, and the polylactic acid resin fine particles are easily fused to each other. The possibility of adversely affecting the shape and particle size distribution is increased.

  Specific examples of the ether organic solvent (C) include dimethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, dipentyl ether, dihexyl ether, dioctyl ether, diisoamyl ether, which are aliphatic chain ethers. , Tert-amyl methyl ether, tert-butyl ethyl ether, butyl methyl ether, butyl ethyl ether, 1-methoxyethane (monoglyme), 1-ethoxyethane, diethylene glycol dimethyl ether (diglyme), ethylene glycol diethyl ether, 2-methoxyethyl ether , Di (ethylene glycol) diethyl ether, di (ethylene glycol) dibutyl ether, triethylene glycol dimethyl ether, aliphatic ring Tetrahydrofuran, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2,2,5,5-tetramethylhydrofuran, 2,3-dihydrofuran, 2,5-dihydrofuran, tetrahydropyran, 3-methyl Tetrahydropyran, 1,4-dioxane, aromatic ethers, anisole, phenetole (ethylphenol), diphenyl ether, 3-phenoxytoluene, p-tolyl ether, 1,3-diphenoxybenzene, 1,2-diphenoxyethane Etc. Among them, from the viewpoint of industrial ease of use, dipropyl ether, diisopropyl ether, dibutyl ether, 1-ethoxyethane, diethylene glycol dimethyl ether (diglyme), ethylene glycol diethyl ether, 2-methoxyethyl ether, di (ethylene glycol) Diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,4-dioxane and anisole are preferred.

  Furthermore, when producing the polylactic acid resin fine particles of the present invention, the ether organic solvent (C) separated from the polylactic acid resin fine particles in the solid-liquid separation step, the polymer (B) and the poly different from the polylactic acid resin. From the viewpoint of simplifying the step of removing the poor solvent (α) of the polylactic acid resin from the poor solvent (α) of the lactic acid resin and recovering the ether organic solvent (C), the ether organic solvent (C) Is preferably higher in boiling point than the poor solvent (α) of the polylactic acid resin. For example, when the poor solvent is water, the boiling point of the ether organic solvent is preferably 100 ° C. or higher. Examples of such a solvent include diethylene glycol dimethyl ether (diglyme) and 1,4-dioxane. These ether organic solvents may be used alone or in combination, but are preferably used alone from the viewpoint of simplifying the step of recovering the ether organic solvent (C).

  Moreover, you may add another organic solvent to the ether type organic solvent (C) in the range which does not impair the effect of this invention. When the amount of the ether-based organic solvent (C) is 100 parts by mass, the amount of other organic solvent added is usually less than 100 parts by mass, preferably 75 parts by mass or less, more preferably 50 parts by mass or less. More preferably, it is 30 parts by mass or less, particularly preferably 20 parts by mass or less, and most preferably 10 parts by mass or less. Examples of other organic solvents include ester solvents such as ethyl acetate and methyl acetate, chloroform, bromoform, methylene chloride, 1,2-dichloroethane, 1,1,1-trichloroethane, chlorobenzene, 2,6-dichlorotoluene and the like. A halogenated hydrocarbon solvent, a ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl butyl ketone, an acetal solvent such as dimethyl acetal, diethyl acetal, dipropyl acetal, dioxolane, N-methyl-2-pyrrolidone, Aprotic polar solvents such as dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, propylene carbonate, trimethyl phosphoric acid, 1,3-dimethyl-2-imidazolidinone, sulfolane, formic acid, acetic acid, Propionic acid, butyric acid, and the like carboxylic acid solvents such as lactic acid. These other organic solvents may be used alone or in combination.

The polylactic acid resin (A) in the present invention is a polymer containing L-lactic acid and D-lactic acid as main components.
It should be noted that L-lactic acid and D-lactic acid are the main constituent components, and the total of L-lactic acid and D-lactic acid monomer units among the monomer units constituting the copolymer in the polylactic acid resin (A) is , Meaning that the molar ratio is 50 mol% or more. The molar ratio is preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and particularly preferably 90 mol% or more. The upper limit is usually 100 mol%.
Here, L or D represents the type of optical isomers of lactic acid. L-lactic acid or L-lactic acid has a natural configuration, and D- has a non-natural configuration. It is expressed as lactic acid or D-form lactic acid.
The copolymerization ratio (L / D) of L-lactic acid and D-lactic acid constituting the polylactic acid resin (A) in the present invention is not particularly limited, but the upper limit is 100/0 and the lower limit is 50/50. is there. The optically active substances such as D and L are substances whose molecular structures are mirror images, and the physical characteristics are not changed at all. Therefore, L / D may be rewritten as D / L.

  In the polylactic acid resin (A), the arrangement pattern of the lactic acid monomer units is not particularly limited, and any of a block copolymer, an alternating copolymer, a random copolymer, and a graft copolymer may be used.

  Furthermore, the polylactic acid-based resin (A) may contain a copolymer component other than lactic acid as long as the effects of the present invention are not impaired. Examples of other copolymer component units include polyvalent carboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, lactones, and the like. Specifically, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, Azelaic acid, sebacic acid, dodecanedioic acid, fumaric acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, anthracene dicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium Polyvalent carboxylic acids such as sulfoisophthalic acid, ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, Resin, pentaerythritol, bisphenol A, aromatic polyhydric alcohol obtained by addition reaction of bisphenol with ethylene oxide, polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, glycolic acid, 3- Hydroxycarboxylic acids such as hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, hydroxybenzoic acid, and glycolide, ε-caprolactone glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone , Β- or γ-butyrolactone, pivalolactone, units produced from lactones such as δ-valerolactone, and the like. The content of such copolymer component units is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, based on 100 mol% of all monomer units. Preferably, 5 mol% or less is most preferable.

  The molecular weight and molecular weight distribution of the polylactic acid-based resin (A) are not particularly limited as long as they can be substantially dissolved in the ether-based organic solvent (C), but the particle structure is easily maintained, and the hydrolysis resistance is improved. In this respect, the lower limit of the weight average molecular weight is preferably 10,000 or more, more preferably 50,000 or more, still more preferably 100,000 or more, and particularly preferably 200,000 or more. The upper limit is not particularly limited, but is usually 1 million or less. The weight average molecular weight herein is a weight average molecular weight in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent.

  The production method of the polylactic acid-based resin (A) is not particularly limited, and a known polymerization method can be used. For example, a direct polymerization method from lactic acid or a ring-opening polymerization method via lactide can be used.

Examples of the polymer (B) different from the polylactic acid resin in the present invention include thermoplastic resins and thermosetting resins. From the viewpoint of being easily dissolved in the ether organic solvent (C), the thermoplastic resin is preferable.
Specifically, poly (vinyl alcohol) (which may be completely saponified or partially saponified poly (vinyl alcohol)), poly (vinyl alcohol-ethylene) copolymer (fully saponified or partially saponified) Saponified poly (vinyl alcohol-ethylene) copolymer), polyvinyl pyrrolidone, poly (ethylene glycol), poly (ethylene oxide), sucrose fatty acid ester, poly (oxyethylene fatty acid ester), poly (Oxyethylene laurin fatty acid ester), poly (oxyethylene glycol monofatty acid ester), poly (oxyethylene alkylphenyl ether), poly (oxyalkyl ether), polyacrylic acid, sodium polyacrylate, polymethacrylic acid, polymethacrylic acid Sodium, polystyrene sulfonic acid, Sodium polystyrene sulfonate, polyvinylpyrrolidinium chloride, poly (styrene-maleic acid) copolymer, aminopoly (acrylamide), poly (paravinylphenol), polyallylamine, polyvinyl ether, polyvinyl formal, poly (acrylamide), poly ( Methacrylamide), poly (oxyethyleneamine), poly (vinyl pyrrolidone), poly (vinyl pyridine), polyaminosulfone, polyethyleneimine, and other synthetic resins, disaccharides such as maltose, cellobiose, lactose, sucrose, cellulose, chitosan, hydroxy Ethyl cellulose, hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxy cellulose, carboxymethyl ethyl cellulose, carboxymethyl Cellulose derivatives such as roulose, sodium carboxymethylcellulose, cellulose ester, amylose and derivatives thereof, starch and derivatives thereof, polysaccharides or derivatives thereof such as dextrin, cyclodextrin, sodium alginate and derivatives thereof, gelatin, casein, collagen, albumin, fibroin , Keratin, fibrin, carrageenan, chondroitin sulfate, gum arabic, agar, protein and the like, and preferably a poly (vinyl alcohol) (fully saponified or partially saponified poly). (May be vinyl alcohol)), poly (vinyl alcohol-ethylene) copolymer (may be fully saponified or partially saponified poly (vinyl alcohol-ethylene) copolymer), Li (ethylene glycol), poly (ethylene oxide), sucrose fatty acid ester, poly (oxyethylene alkylphenyl ether), poly (oxyalkyl ether), poly (acrylic acid), poly (methacrylic acid), carboxymethylcellulose, hydroxyethylcellulose , Hydroxypropylcellulose, methylcellulose, ethylcellulose, ethylhydroxycellulose, carboxymethylethylcellulose, carboxymethylcellulose, carboxymethylcellulose sodium, cellulose derivatives such as cellulose ester, and polyvinylpyrrolidone, more preferably poly (vinyl alcohol) (fully saponified type) Or partially saponified poly (vinyl alcohol)), poly (vinyl alcohol-ethylene) copolymer (Fully saponified or partially saponified poly (vinyl alcohol-ethylene) copolymer), poly (ethylene glycol), poly (ethylene oxide), carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, ethylcellulose, ethyl A cellulose derivative such as hydroxycellulose, carboxymethylethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose ester, and polyvinylpyrrolidone, particularly preferably poly (vinyl alcohol) (fully saponified or partially saponified poly (vinyl alcohol) ), Poly (ethylene glycol), poly (ethylene oxide), hydroxypropylcellulose.

The range of the molecular weight of the polymer (B) different from the polylactic acid-based resin is preferably 1,000 to 100,000,000, more preferably 1,000 to 10,000,000, even more preferably in terms of weight average molecular weight. Is from 5,000 to 1,000,000, particularly preferably from 10,000 to 500,000, most preferably from 10,000 to 100,000. The weight average molecular weight here refers to a weight average molecular weight measured by gel permeation chromatography (GPC) using water as a solvent and converted into polyethylene glycol.
In addition, when it cannot measure with water, dimethylformamide is used as a solvent, when it still cannot be measured, tetrahydrofuran is used, and when it cannot be measured, hexafluoroisopropanol is used.

  In the above-mentioned production method, “a system that phase-separates into two phases, a solution phase mainly composed of polylactic acid resin (A) and a solution phase mainly composed of polymer (B) different from polylactic acid resin”. Is a system comprising a solution in which a polylactic acid resin (A) and a polymer (B) different from the polylactic acid resin are dissolved in an ether organic solvent (C). The system is divided into two phases, a solution phase mainly containing a lactic acid resin (A) and a solution phase mainly containing a polymer (B) different from a polylactic acid resin. An emulsion is formed by stirring and emulsifying such a system under conditions for phase separation.

  In the above, whether or not the polymer is dissolved depends on the temperature at which the dissolution step is carried out, that is, the polymer (B) different from the polylactic acid resin (A) and the polylactic acid resin in the ether organic solvent (C). It discriminate | determines in the temperature at the time of making it melt | dissolve with respect to ether type organic solvent (C) whether the polymer (B) different from polylactic acid-type resin (A) and polylactic acid-type resin melt | dissolves 1 mass% or more.

  In the above emulsion, the polylactic acid resin solution phase becomes a dispersed phase, and the polymer B solution phase different from the polylactic acid resin becomes a continuous phase. Then, by bringing the poor solvent (α) of the polylactic acid resin into contact with the emulsion, polylactic acid resin fine particles are precipitated from the polylactic acid resin solution phase in the emulsion, and the polylactic acid resin (A) The polymer fine particle comprised by this can be obtained.

  Here, the poor solvent (α) of the polylactic acid-based resin means that the solubility of the polylactic acid-based resin (A) is smaller than that of the above-mentioned ether-based organic solvent (C) and hardly dissolves the polylactic acid-based resin (A). It refers to a solvent. Specifically, the solubility of the polylactic acid resin (A) is 1% by mass or less. In addition, the upper limit of solubility is more preferably 0.5% by mass or less, and further preferably 0.1% by mass or less.

  The poor solvent (α) of the polylactic acid resin used in the above production method is a poor solvent of the polylactic acid resin (A) and a solvent that dissolves the polymer (B) different from the polylactic acid resin. Preferably there is. Thereby, the polylactic acid-type resin fine particle comprised with a polylactic acid-type resin (A) can be precipitated efficiently. Moreover, it is preferable that the poor solvent ((alpha)) of a polylactic acid-type resin is a solvent mixed uniformly with the solvent which melt | dissolves the polymer (B) different from a polylactic acid-type resin (A) and a polylactic acid-type resin.

As the poor solvent (α) of the polylactic acid-based resin, the type of the polylactic acid-based resin (A) to be used, preferably the types of the polylactic acid-based resin (A) to be used and the polymer (B) different from the polylactic acid-based resin are used. According to specific examples, aliphatic hydrocarbons such as pentane, hexane, heptane, octane, nonane, n-decane, n-dodecane, n-tridecane, cyclohexane, cyclopentane, etc. Solvent, aromatic hydrocarbon solvent such as benzene, toluene and xylene, alcohol solvent such as methanol, ethanol, 1-propanol, 2-propanol and n-nonanol, and at least one solvent selected from the group consisting of water, etc. Is mentioned.
In addition, from the viewpoint of efficiently granulating the polylactic acid resin (A), the poor solvent (α) for the polylactic acid resin is preferably an aromatic hydrocarbon solvent, an aliphatic hydrocarbon solvent, an alcohol solvent. A solvent and water are more preferable, and an alcohol solvent and water are more preferable, and water is most preferable.

  Thus, the polylactic acid resin (A), the polymer (B) different from the polylactic acid resin, the ether organic solvent (C) for dissolving them, and the poor solvent (α) of the polylactic acid resin are appropriately selected. By combining them, it is possible to efficiently precipitate the polylactic acid resin and obtain polymer fine particles.

  The liquid obtained by mixing and dissolving the polylactic acid resin (A) and the polymer (B) different from the polylactic acid resin in the ether organic solvent (C) has a solution phase containing the polylactic acid resin (A) as a main component. It is necessary to phase-separate into two phases of a solution phase mainly composed of a polymer (B) different from the polylactic acid resin. At this time, an ether-based organic solvent (C) in a solution phase mainly comprising a polylactic acid-based resin (A) and an ether-based organic solvent (C) mainly comprising a polymer (B) different from the polylactic acid-based resin. May be the same or different, but are preferably substantially the same solvent.

The conditions for generating the two-phase separation state are the polylactic acid resin (A) or the type of polymer (B) different from the polylactic acid resin, the polylactic acid resin (A) or a polymer different from the polylactic acid resin ( Depends on the molecular weight of B), the type of ether-based organic solvent (C), the concentration of polymer (B) different from polylactic acid-based resin (A) or polylactic acid-based resin, the temperature and pressure at which the dissolution step is carried out Come.
Therefore, in order to obtain conditions that are likely to result in a phase-separated state, the difference in solubility parameter (hereinafter also referred to as SP value) of the polymer (B) different from the polylactic acid resin (A) and the polylactic acid resin. Are preferably separated.

At this time, the lower limit of the difference in SP value is preferably 1 (J / cm ³ ) ^1/2 or more, more preferably 2 (J / cm ³ ) ^1/2 or more, and further preferably 3 (J / cm ^3). ) ^1/2 or more, particularly preferably 5 (J / cm ³ ) ^1/2 or more, most preferably 8 (J / cm ³ ) ^1/2 or more. If the SP value is within this range, the phase separation is facilitated and the phase separation is facilitated, so that polylactic acid resin fine particles having a higher content of the polylactic acid resin component can be obtained. There is no particular limitation as long as both the polylactic acid-based resin (A) and the polymer (B) different from the polylactic acid-based resin are soluble in the ether-based organic solvent (C). It is 20 (J / cm ³ ) ^1/2 or less, more preferably 15 (J / cm ³ ) ^1/2 or less, and further preferably 10 (J / cm ³ ) ^1/2 or less.

  The SP value here is calculated based on the Fedor's estimation method. Specifically, the SP value is calculated based on the cohesive energy density and the molar molecular weight (Hideki Yamamoto, “SP value basis ・Application and calculation method "Information Organization Co., Ltd., issued on March 31, 2005). In addition, when this method cannot be used for calculation, an SP value is calculated based on the determination as to whether or not it dissolves in a known solvent, and it is used as a substitute (J. Brand, “Polymer Handbook No. 1”). 4th Edition (Polymer Handbook Fourth Edition) ”Wiley, 1998).

  The conditions for achieving the phase separation state can be discriminated by the three-component phase diagram of the polylactic acid resin (A), the polymer (B) different from the polylactic acid resin, and the ether organic solvent (C) for dissolving them. This three-component phase diagram can be created by a simple preliminary experiment by observing a state in which the ratio of each component is changed. Specifically, first, the polylactic acid resin (A), the polymer (B) different from the polylactic acid resin, and the ether organic solvent (C) are mixed and dissolved in an arbitrary ratio, and left to stand for a certain period of time. It is determined whether an interface is generated. Then, this determination is performed with at least 3 points, preferably 5 points or more, more preferably 10 points or more, and a phase diagram is created based on the determination results. By using this phase diagram to distinguish the region that separates into two phases and the region that becomes one phase, the conditions for the phase separation state can be determined.

  In order to determine whether or not the phase separation state, after adjusting the polylactic acid resin (A), the polymer (B) different from the polylactic acid resin and the ether organic solvent (C) to an arbitrary ratio, Under the same temperature and pressure conditions as in the dissolution step, the polylactic acid resin (A) and the polymer (B) different from the polylactic acid resin are completely dissolved in the ether organic solvent (C) and sufficiently stirred. . And after leaving still for 3 days, it confirms whether a phase separation is carried out macroscopically. However, when a sufficiently stable emulsion is produced, macroscopic phase separation may not occur even after standing for 3 days. In such a case, the presence / absence of phase separation is determined based on whether or not the phase separation is microscopically using an optical microscope or a phase contrast microscope.

  The phase separation state includes a polylactic acid resin solution phase mainly composed of a polylactic acid resin (A) in an ether organic solvent (C) and a polymer B mainly composed of a polymer (B) different from the polylactic acid resin. Formed by separation into solution phase. Here, the polylactic acid resin solution phase is a phase in which the polylactic acid resin (A) is mainly distributed, and the polymer B solution phase is a phase in which the polymer (B) different from the polylactic acid resin is mainly distributed. It is. At this time, it is estimated that the polylactic acid resin solution phase and the polymer B solution phase have a volume ratio corresponding to the type and amount of the polymer (B) different from the polylactic acid resin (A) and the polylactic acid resin. The

  From the viewpoint that a phase-separated state is obtained and can be industrially implemented, one of the conditions necessary for precipitating polylactic acid resin fine particles having a number average particle diameter of 1 μm or less is polylactic acid-based. The mass ratio (A / B) of the polymer (B) different from the resin (A) and the polylactic acid resin is 0.8 or less. The range of the mass ratio (A / B) is preferably 0.5 or more and 0.8 or less, and more preferably 0.5 or more and 0.7 or less. When the mass ratio (A / B) is larger than this, the number average particle diameter becomes 1 μm or more, and when the mass ratio (A / B) is small, the economic efficiency deteriorates.

  Further, the total mass concentration (A + B mass concentration) of the polymer (B) different from the polylactic acid resin (A) and the polylactic acid resin is preferably 5 to 15%, more preferably 5 to 10%. If the total mass concentration of the polymer is high, the viscosity at the time of forming the emulsion may increase, and the load during stirring may increase, and if the total mass concentration of the polymer is low, the economic efficiency deteriorates.

  Since both the polylactic acid resin solution phase and the polymer B solution phase are organic solvents, the interfacial tension between the two phases is small. And, it is presumed that due to the small interfacial tension, the produced emulsion is stably maintained and the particle size distribution becomes small.

As described above, since the interfacial tension between the two phases is very small, it cannot be directly measured by a commonly used method such as the hanging drop method in which a different kind of solution is added to the solution. By estimating from the surface tension, the size of the interfacial tension can be estimated. When the surface tension of each phase with air is r ₁ and r ₂ , the interfacial tension r _1/2 between the two phases is r _1/2 = | r ₁ −r ₂ | (absolute value of r ₁ −r ₂ ). Can be estimated.
From the viewpoint of reducing the particle size distribution, the upper limit of r _1/2 is preferably 10 mN / m, more preferably 5 mN / m, still more preferably 3 mN / m, and particularly preferably 2 mN / m. m. The lower limit is more than 0 mN / m.

The viscosity ratio between the two phases affects the average particle size and particle size distribution, and the smaller the viscosity ratio, the smaller the particle size distribution.
The lower limit of the viscosity ratio between the two phases is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, particularly preferably 0.5 or more, and extremely preferably 0.8 or more. The upper limit is preferably 10 or less, more preferably 5 or less, further preferably 3 or less, particularly preferably 1.5 or less, and particularly preferably 1.2 or less. The viscosity ratio between the two phases here is defined as “viscosity of polylactic acid resin solution phase / viscosity of polymer B solution phase” under the same temperature conditions as in the dissolution step.

  In the present invention, the emulsion formation step of emulsifying the phase-separated system thus obtained, and the poor solvent (α) of the polylactic acid resin are brought into contact with the emulsion to precipitate the polylactic acid resin fine particles. The polylactic acid resin is made into fine particles from the particle precipitation step. In addition, you may implement an emulsion formation process simultaneously with the said melt | dissolution process.

  A normal reaction tank can be used for the above-mentioned fine particle formation. The temperature at which the emulsion formation step and the particle precipitation step are performed is a temperature at which the polylactic acid resin (A) and the polymer (B) different from the polylactic acid resin are dissolved and phase-separated, and the desired fine particles can be obtained. Although there is no restriction | limiting in particular, from a viewpoint of industrial economical efficiency, as a minimum of implementation temperature, it is 0 degreeC or more normally, Preferably it is 10 degreeC or more, More preferably, it is 20 degreeC or more. Moreover, as an upper limit of implementation temperature, Preferably it is 300 degrees C or less, More preferably, it is 200 degrees C or less, More preferably, it is 160 degrees C or less, Especially preferably, it is 140 degrees C or less, Most preferably, it is 100 degrees C or less It is.

  The pressure at the time of carrying out the above step is usually 30 atm or less, for example, less than 1 atm, from the viewpoint of industrial economy. A preferable pressure range is 1 to 10 atm, more preferably 1 to 5 atm, more preferably 1 to 3 atm, and most preferably 1 to 2 atm. .

  The reaction vessel is preferably used in an inert gas atmosphere. Specifically, nitrogen, helium, argon, and carbon dioxide are preferable, and nitrogen and argon are preferable.

  Under such conditions, an emulsion is formed by stirring the system for phase separation. That is, an emulsion is formed by applying a shearing force to the phase separation system obtained above.

  The fine particles obtained by the production method according to the present invention are fine particles having a small particle size distribution because a very uniform emulsion can be obtained at the stage of emulsion formation. This tendency is particularly remarkable when a single solvent that dissolves both the polylactic acid resin (A) and the polymer (B) different from the polylactic acid resin is used.

  In order to obtain a sufficient shear force to form an emulsion, it is sufficient to use stirring by a conventionally known method, a liquid phase stirring method using a stirring blade, a stirring method using a continuous biaxial mixer, a mixing method using a homogenizer, Stirring can be performed by a known method such as ultrasonic irradiation.

  What is necessary is just to select optimal conditions for the stirring speed according to the magnitude | size of a reaction tank, the shape of a stirring blade, etc. For example, in the case of stirring with a stirring blade, particularly when the reaction tank is 1 L scale and a paddle type is used as the stirring blade, the stirring speed is preferably 150 rpm to 1,100 rpm, more preferably 200 rpm to 800 rpm. More preferably, it is 250 rpm to 600 rpm.

  Specific examples of the stirring blade include a propeller type, a paddle type, a flat paddle type, a turbine type, a double cone type, a single cone type, a single ribbon type, a double ribbon type, a screw type, and a helical ribbon type. As long as a sufficient shearing force can be applied to the system, it is not particularly limited thereto. Moreover, in order to perform efficient stirring, you may install a baffle board etc. in a tank.

  In order to generate an emulsion, not only a stirrer but also a widely known device such as an emulsifier and a disperser may be used. Specifically, a batch emulsifier such as a homogenizer (manufactured by IKA), polytron (manufactured by Kinematica), TK auto homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), Ebara Milder (manufactured by Ebara Seisakusho) , TK fill mix, TK pipeline homomixer (manufactured by Koki Kogyo Co., Ltd.), colloid mill (manufactured by Shinko Pantech Co., Ltd.), slasher, trigonal wet pulverizer (manufactured by Mitsui Miike Chemical Co., Ltd.), ultrasonic homogenizer, static For example, a mixer.

In the emulsion formation step, the stirring power per unit volume (Pv) (hereinafter referred to as stirring power (Pv)) is particularly important, and the stirring power (Pv) needs to be 0.01 kW / m ³ or more. . The scope of the stirring power, preferably 0.01~2.0kW / ^{m 3,} more preferably 0.02~1.0kW / ^{m 3.} When the stirring power is smaller than this, a sufficient stirring effect cannot be obtained at the time of forming the emulsion, and particles having a number average particle diameter of 1 μm or more can be formed. The stirring power (Pv) here is obtained by the following formula.

Note that Pv: stirring power (kW / m ³ ), P: stirring station power (kW), and V: liquid capacity (m ³ ).

  The power for stirring station (P) here is calculated | required by a following formula.

In addition, P: Power for stirring station (kW), Np: Power number in stirring (−), ρ: Liquid density (kg / m ³ ), n: Number of rotations (rps), d: Stirring blade diameter (m) . In addition, a unit represented by (−) is a dimensionless number.

  As the power number (Np) in the stirring, the value calculated by the following formula according to Nagata's formula was used.

  Re: Stirring Reynolds number (−), d: Stirring blade diameter (m), H: Liquid depth (m), D: Tank diameter (m), b: Stirring blade width (m), θ: Stirring blade The angle (rad).

  The stirring Reynolds number (Re) can be calculated by the following formula, and the calculation formula varies depending on the presence or absence of a baffle plate.

Re: Stirring Reynolds number without baffle (−), d: Stirring blade diameter (m), ρ: Liquid density (kg / m ³ ), n: Number of rotations (rps), μ: Liquid viscosity (Pa · s) ), Rc: Stirring Reynolds number (-) with baffle plate, b: Stirring blade width (m), D: Tank diameter (m).
However, the stirring Reynolds number (Rc) with the baffle plate is the minimum stirring Reynolds number at which the Reynolds number becomes a constant value. Therefore, when Rc> Re, the stirring Reynolds without the baffle plate is provided even if the baffle plate is provided The number (Re) was used.

  The emulsion thus obtained is subsequently subjected to a particle precipitation step. Specifically, the addition step of bringing the poor solvent (α) of the polylactic acid resin into contact with the emulsion produced in the emulsion generation step and the contact state between the poor solvent (α) of the polylactic acid resin and the emulsion are maintained. By the contact step, fine particles are deposited with a diameter corresponding to the emulsion diameter.

  There is no restriction | limiting in the contact method of the poor solvent and emulsion in an addition process, The method of adding an emulsion to a poor solvent may be sufficient, and the method of adding a poor solvent to an emulsion may be sufficient, but the method of adding a poor solvent to an emulsion is preferable.

  The method for adding the poor solvent or the emulsion is not particularly limited as long as the desired polymer fine particles can be obtained, and any of the continuous addition method, the divided addition method, and the batch addition method may be used. In order to prevent the particle size distribution from becoming unity and forming a lump with a size exceeding 1000 μm, it is preferable to use the continuous addition method or the divided addition method, and the dropping method is particularly preferable. In order to carry out industrially efficiently, the continuous dropping method is most preferable.

  The temperature at which the poor solvent (α) of the polylactic acid resin is brought into contact with the emulsion is not particularly limited as long as the polylactic acid resin fine particles are precipitated, but if the temperature is too low, the poor solvent is solidified and used. Since it becomes impossible, 0 degreeC or more is preferable as a minimum of temperature, 10 degreeC or more is more preferable, and 20 degreeC or more is further more preferable. Further, if the temperature is too high, thermal degradation of the polylactic acid resin (A) or the polymer (B) different from the polylactic acid resin tends to proceed, so the upper limit of the temperature is preferably 300 ° C. or less. ° C or less is more preferred, 100 ° C or less is more preferred, and 90 ° C or less is most preferred.

In order to precipitate polylactic acid resin fine particles having a number average particle diameter of 1 μm or less, the time required for the addition step is 10 minutes or more and 90 minutes or less, more preferably 20 minutes or more and 80 minutes or less, It is preferably 30 minutes or more and 70 minutes or less, and most preferably 30 minutes or more and 60 minutes or less.
If the time is longer or shorter than this range, the particle size distribution may increase or polylactic acid resin fine particles having a particle size of 1 μm or more may be generated due to aggregation, fusion, and coalescence of the emulsion. is there.
By carrying out within this time range, it is possible to suppress aggregation between particles when converting from emulsion to polymer fine particles, and to obtain polymer fine particles having a particle size smaller than 1 μm and a narrow particle size distribution. it can.

  The amount of the poor solvent used in the addition step depends on the state of the emulsion, but is preferably from 0.1 to 10 parts by mass, more preferably from 0.1 to 10 parts by mass with respect to 1 part by mass of the total emulsion. 5 parts by weight, more preferably 0.2 parts by weight to 3 parts by weight, particularly preferably 0.2 parts by weight to 2 parts by weight, and most preferably 0.2 parts by weight to 1.0 parts by weight. .

  The contact time between the poor solvent and the emulsion in the contact step after the addition step may be a sufficient time for the fine particles to precipitate, but in order to cause sufficient precipitation and to obtain efficient productivity, contact is required. The time range is from 5 minutes to 50 hours after the addition of the poor solvent, more preferably from 5 minutes to 10 hours, further preferably from 10 minutes to 5 hours, and particularly preferably from 20 minutes to 4 hours. Yes, most preferably 30 minutes or more and 3 hours or less.

The fine particle powder is recovered by solid-liquid separation of the polymer fine particle dispersion thus obtained by a known method such as filtration, vacuum filtration, pressure filtration, centrifugal separation, centrifugal filtration, spray drying and the like. I can do it.
In addition, the polymer fine particles recovered in the solid-liquid separation step are purified by removing impurities attached or contained by washing with a solvent or the like, if necessary.

  In the production method of the present invention, the ether organic solvent (C) and the polymer (B) different from the polylactic acid resin separated in the solid-liquid separation step performed when obtaining the fine particle powder are used again as raw materials. It is possible to recycle.

  The solvent obtained in the solid-liquid separation step is a mixture of a polymer (B) different from the polylactic acid resin, an ether organic solvent (C), and a poor solvent (α) of the polylactic acid resin. By removing the poor solvent from this mixture and adding the polylactic acid resin (A), it can be reused for emulsion formation. As a method for removing the poor solvent, it is sufficient to use a known method, and specific examples include simple distillation, vacuum distillation, precision distillation, thin film distillation, extraction, membrane separation, etc., preferably simple distillation. , Vacuum distillation, precision distillation, thin film distillation.

  When performing the distillation operation, heat is applied to the system, as in the case of the production of polymer fine particles, and there is a possibility that the thermal decomposition of the polymer (B) and the ether organic solvent (C) different from the polylactic acid resin may be promoted. Therefore, the reaction is preferably performed in a state free from oxygen as much as possible, and more preferably in an inert atmosphere. Specifically, it is preferably carried out under inert conditions such as nitrogen, helium, argon, carbon dioxide. Moreover, you may add antioxidant. As the antioxidant, a phenolic compound is preferable. Moreover, you may use antioxidant together in inert atmosphere.

  When recycling the polymer (B) different from the polylactic acid resin, it is preferable to remove the poor solvent as much as possible. Specifically, the remaining amount of the poor solvent is 10% by mass or less, preferably 5% by mass with respect to the total amount of the ether-based organic solvent (C) to be recycled and the polymer (B) different from the polylactic acid-based resin. Hereinafter, it is more preferably 3% by mass or less, and particularly preferably 1% by mass or less. If the remaining amount of the poor solvent exceeds this range, the particle size distribution of the fine particles may be increased, or the particles may be aggregated.

  The amount of the poor solvent in the solvent used for recycling can be measured by a known method, such as a gas chromatography method or a Karl Fischer method.

  In the operation of removing the poor solvent, in reality, the ether organic solvent (C), the polymer (B) different from the polylactic acid resin may be lost, and the initial composition ratio is appropriately adjusted. It is preferable to fix it.

Hereinafter, the polylactic acid resin fine particles of the present invention will be described in detail.
The number average particle diameter of the polylactic acid-based resin fine particles in the present invention is usually 10 nm or more and 1 μm or less. The upper limit thereof is preferably less than 1 μm, more preferably 800 nm or less, further preferably 600 nm or less, particularly preferably 500 nm, extremely preferably 400 nm or less, and most preferably 350 nm or less. . Further, the lower limit thereof is preferably 30 nm or more, more preferably 50 nm, further preferably 80 nm, particularly preferably 100 nm or more, extremely preferably 120 nm or more, and most preferably 150 nm or more. is there.

  The polylactic acid-based resin fine particles are characterized by a narrow particle size distribution, and the particle size distribution index indicating the particle size distribution is usually 2 or less, and according to a preferred embodiment is 1.5 or less. According to a preferred embodiment, it is 1.3 or less, and according to a most preferred embodiment, it is 1.2 or less. The lower limit is theoretically 1.

  The number average particle diameter of the polylactic acid resin fine particles referred to here can be calculated by measuring the diameter of 100 random particles using a scanning electron micrograph and calculating the arithmetic average thereof. . In the micrograph, when the particle shape is not a perfect circle, that is, when it is elliptical, the maximum particle diameter is taken as the particle diameter. In order to accurately measure the particle diameter, it is measured at a magnification of at least 20,000 times, preferably at least 25,000 times.

  The particle size distribution index is calculated by substituting the measured value of the particle diameter obtained by the above measuring method into the following numerical conversion formula.

  Ri: particle size of each particle, n: number of measurements (= 100), Dn: number average particle size, Dv: volume average particle size, PDI: particle size distribution index.

The shape of the polylactic acid-based resin fine particles in the present invention may be any shape, and examples thereof include a true sphere shape, an elliptic sphere shape, a flat shape, a rock shape, and a confetti shape. Of these, spherical and oval spherical ones are preferable, and a spherical shape is particularly preferable.
The sphericity representing the sphericity of the polylactic acid-based resin fine particles in the present invention is usually 90 or more, 92 or more according to a preferred embodiment, and 95 or more according to a more preferred embodiment. The upper limit is 100. The sphericity is calculated by observing particles with a scanning electron microscope, measuring the short diameter and long diameter of 30 randomly selected particles, and substituting the measured values into the following mathematical formulas.

  Note that n is the number of measurements (= 30).

  Hereinafter, the polylactic acid resin fine particle dispersion of the present invention will be described.

The polylactic acid resin fine particle dispersion of the present invention is a dispersion in which the polylactic acid resin fine particles are dispersed in a dispersion medium.
Specific examples of the dispersion medium include pentane, hexane, heptane, octane, nonane, n-decane, n-dodecane, n-tridecane, cyclohexane, cyclopentane, and other aliphatic hydrocarbon solvents, benzene, toluene. , Aromatic hydrocarbon solvents such as xylene, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, 3-pentanone, ether solvents such as diethyl ether, dipropyl ether, tetrahydrofuran, diethylene glycol dimethyl ether, methyl acetate, ethyl acetate And an ester solvent such as methanol, ethanol, 1-propanol, 2-propanol and n-nonanol, and at least one selected from water.

  Further, a surfactant may be added in order to efficiently disperse the polylactic acid resin fine particles in the dispersion medium. Surfactants include cationic surfactants such as alkylmethylammonium chloride, alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, alkyldimethylbenzylammonium chloride, alkylpyridinium chloride, fatty acid sodium, fatty acid potassium, sodium alkylbenzenesulfonate, alkyl Sodium sulfate ester, sodium alkyl sulfonate, sodium alkyl ether sulfate, monoalkyl phosphate, polyoxyethylene alkyl ether sodium phosphate, sodium fatty acid ester sulfonate, sodium fatty acid ester sulfate, fatty acid alkylose amide sulfate sodium , Anionic surfactants such as sodium fatty acid amide sulfonate, alkyl amines Zwitterionic surfactants such as polycarboxylates, carboxybetaines, alkylbetaines, sulfobetaines and phosphobetaines, poly (vinyl alcohol) (may be fully or partially saponified poly (vinyl alcohol)) , Poly (vinyl alcohol-ethylene) copolymers (which may be fully saponified or partially saponified poly (vinyl alcohol-ethylene) copolymers), poly (ethylene glycol), poly (ethylene oxide), Sucrose fatty acid ester, poly (oxyethylene alkylphenyl ether), poly (oxyalkyl ether), poly (acrylic acid), poly (methacrylic acid), carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, ethylcellulose, ethylhydride Roxycellulose, carboxymethylethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose derivatives such as cellulose ester, and polyvinylpyrrolidone, more preferably poly (vinyl alcohol) (fully saponified or partially saponified poly (vinyl alcohol) ), Poly (vinyl alcohol-ethylene) copolymer (fully saponified or partially saponified poly (vinyl alcohol-ethylene) copolymer), poly (ethylene glycol), poly (ethylene oxide) ), Carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, ethylcellulose, ethylhydroxycellulose, carboxymethylethylcellulose, carboxyme Cellulose derivatives such as cellulose, sodium carboxymethylcellulose, cellulose ester, and polyvinylpyrrolidone, particularly preferably poly (vinyl alcohol) (may be fully saponified or partially saponified poly (vinyl alcohol)), Nonionic surfactants such as poly (ethylene glycol), poly (ethylene oxide), and hydroxypropylcellulose are listed. As used herein, alkyl is, for example, a linear saturated hydrocarbon group, a linear unsaturated hydrocarbon group, a branched saturated hydrocarbon group or a branched unsaturated hydrocarbon group having 2 to 30 carbon atoms. Can be mentioned.

The addition amount of these surfactants is 0.01 to 100 parts by mass with respect to 100 parts by mass of the polylactic acid-based resin fine particles, and the upper limit thereof is preferably 80 parts by mass, more preferably 60 parts by mass. Yes, more preferably 50 parts by mass, particularly preferably 30 parts by mass. The lower limit thereof is preferably 0.5 parts by mass, more preferably 1 part by mass, still more preferably 2 parts by mass, and particularly preferably 4 parts by mass.
By using an amount of the polymer surfactant in this range, the polylactic acid resin fine particles obtained by mechanical dispersion can be dispersed uniformly in the dispersion medium very efficiently.

  The content of the polylactic acid resin fine particles in the polylactic acid resin fine particle dispersion used for mechanical dispersion is preferably 1 to 50 parts by mass, more preferably 1 to 30 parts by mass with respect to 100 parts by mass of the dispersion medium. is there.

  Examples of the mechanical dispersion device include a commercially available mechanical dispersion device. Particularly suitable mechanical dispersion devices include an ultrasonic dispersion device, a ball mill device, a bead mill device, a sand mill device, a colloid mill device, and a wet atomization device (for example, an optimizer manufactured by Sugino Machine). An apparatus selected from a dispersion apparatus, a bead mill apparatus, a colloid mill apparatus, and a wet atomization apparatus is preferable. The average particle size of the resulting fine particles tends to decrease as the dispersion force during mechanical dispersion generally increases and the dispersion time increases. However, if these are excessive, reaggregation tends to occur. It is controlled in the range. For example, the bead mill can be controlled by selecting the bead diameter and the bead amount and adjusting the peripheral speed, and the ultrasonic dispersing device can be controlled by selecting the ultrasonic frequency and adjusting the ultrasonic output.

  In some cases, the polylactic acid resin fine particle dispersion may include coarse particles or precipitates. In that case, coarse particles or precipitates may be separated from the dispersed portion. When only the dispersion liquid is obtained, the coarse particles and precipitates may be separated from the dispersed portion, and the coarse particles and the precipitated portion may be removed by decantation, filtration, centrifugation and the like.

In addition, as a method of making polylactic acid resin fine particles into a dispersion without solid-liquid separation, polylactic acid resin fine particles are obtained by using a polylactic acid resin poor solvent (α) and an ether organic solvent (C). After the preparation, the polylactic acid resin fine particle dispersion of the ether organic solvent (C) is removed by removing the poor solvent (α) from the system, or the poor solvent is obtained by removing the ether organic solvent (C) from the system. There is a method of preparing a polylactic acid resin fine particle dispersion of (α). As a method for removing the organic solvent or the poor solvent, any method can be used as long as it can be separated, and examples thereof include separation operations such as distillation, extraction, and membrane separation. Of these, separation by distillation is simple and preferred. If an ether organic solvent (C) having a lower boiling point than the poor solvent (α) of the polylactic acid resin is used, the ether organic solvent (C) is removed after the polylactic acid resin fine particles are prepared. A polylactic acid resin fine particle dispersion of the solvent (α) can be prepared.
For example, after preparing polylactic acid resin fine particles using tetrahydrofuran as an ether organic solvent (C) and water as a poor solvent (α), tetrahydrofuran is distilled off to obtain an aqueous dispersion of polylactic acid resin fine particles. Can be created.

  As described above, a dispersion of polylactic acid resin fine particles in which polylactic acid resin fine particles are finely dispersed can be obtained.

  As described above, since the polylactic acid resin fine particles according to the present invention have a particle size smaller than that of the conventional polylactic acid resin fine particles using an emulsion, it is easier to obtain a biodegradable effect. Polylactic acid resin fine particles having a small particle size, a true spherical shape and a narrow particle size distribution can be used extremely usefully and practically in various applications in industry. Specifically, skin care products additives such as face wash, sunscreen agent, cleansing agent, lotion, milky lotion, beauty essence, cream, cold cream, after shaving lotion, shaving soap, oil blotting paper, matifant agent, Cosmetics such as foundation, funny, watery, mascara, face powder, sky, eyebrow, mascara, eyeline, eye shadow, eye shadow base, nose shadow, lipstick, gloss, cheek, tuna, nail polish, top coat Or its modifiers, shampoos, dry shampoos, conditioners, rinses, rinse-in shampoos, treatments, hair tonics, hair styling agents, hair oils, pomades, hair coloring agents and other hair care product additives, perfumes, eau de cologne, deodora Additives for toiletries, baby powder, toothpaste, mouthwash, lip balm, soap, etc., toner additives, rheology modifiers such as paints, medical diagnostic inspection agents, automotive materials, building materials, etc. Mechanical property improvers for products, mechanical property improvers such as films and fibers, raw materials for resin moldings such as rapid prototyping and rapid manufacturing, flash molding materials, paste resins for plastic sol, powder blocking materials, powders Body fluidity improver, lubricant, rubber compounding agent, abrasive, thickener, filter agent and filter aid, gelling agent, flocculant, paint additive, oil absorbent, mold release agent, plastic film Various modifications such as sheet slipperiness improver, antiblocking agent, gloss modifier, matte finish, light diffusing agent, surface high hardness improver, toughness improver, etc. Agents, Liquid Crystal Display Spacers, Chromatographic Fillers, Cosmetic Foundation Substrates / Additives, Microcapsule Auxiliaries, Drug Delivery Systems, Diagnostic Agents, and Other Medical Materials, Fragrance / Agrochemical Retaining Agents, Chemical Reactions It can be used for catalyst for use and its support, gas adsorbent, sintered material for ceramic processing, standard particles for measurement and analysis, particles for food industry, powder coating material, toner for electrophotographic development, etc. .

  In addition, the polylactic acid-based resin fine particles are raw materials derived from non-fossilized raw materials and have properties as environmentally friendly materials, so there is a possibility of replacing the polymer fine particles that have been used in the past. Specific applications of body, film, fiber, etc. include, for example, electrical equipment housings, OA equipment housings, various covers, various gears, various cases, sensors, LED lamps, connectors, sockets, resistors, relay cases, switches Various terminal boards, plugs, printed wiring boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, housings, semiconductors, LCDs, FDD carriages, FDD chassis, motor brush holders, parabolic antennas, computer related Represented by parts, etc. Electric / electronic parts, TV parts, irons, hair dryers, rice cooker parts, microwave oven parts, acoustic parts, audio equipment parts such as audio / laser discs (registered trademark) / compact discs, cameras, VTRs, projection TVs, etc. Lenses, finder, filters, prisms, Fresnel lenses and other video equipment related parts, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, word processor parts, home appliances, office computer parts, office computer parts, Telephone-related parts, facsimile-related parts, copier-related parts, various disk substrate protective films, optical disk player pickup lenses, optical fibers, optical switches, optical connectors, and other information equipment-related parts, liquid crystal displays, Light guide plate for panel display, plasma display, Fresnel lens, polarizing plate, polarizing plate protective film, retardation film, light diffusion film, viewing angle widening film, reflective film, antireflection film, antiglare film, brightness enhancement film, prism sheet , Touch panel light guide film, cleaning jig, motor parts, lighters, typewriters and other machine related parts, microscopes, binoculars, watches and other optical equipment, precision machine parts, fuel related and exhaust System / intake system pipes, air intake nozzle snorkel, intake manifold, fuel pump, fuse connector, horn terminal, electrical component insulation plate, lamp socket, lamp reflector, lamp housing, engine oil filter and ignition device case It is extremely effective for these various applications.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these.

(1) Measuring method of weight average molecular weight (i) Measuring method of molecular weight of polylactic acid resin The weight average molecular weight (Mw) is compared with a calibration curve by polymethyl methacrylate (PMMA) using gel permeation chromatography. The molecular weight was calculated.
Apparatus: LC system manufactured by Waters Inc. Column: HFIP-806M × 2 manufactured by Showa Denko KK Mobile phase: sodium trifluoroacetate 10 mmol / L hexafluoroisopropanol solution Flow rate: 1.0 ml / min
Detection: differential refractometer Column temperature: 30 ° C

(Ii) Method for measuring molecular weight of polymer different from polylactic acid resin The weight average molecular weight was calculated by using gel permeation chromatography method and comparing with a calibration curve by polyethylene glycol.
Apparatus: LC-10A series manufactured by Shimadzu Corporation Column: GF-7MHQ x 2 manufactured by Showa Denko KK Mobile phase: 10 mmol / L lithium bromide aqueous solution Flow rate: 1.0 ml / min
Detection: differential refractometer Column temperature: 40 ° C

(2) Method of measuring number average particle size and particle size distribution index About the particle size of the fine particles, the fine particles were 30,000 times with a scanning electron microscope (JEM-6700F manufactured by JEOL Ltd.). Observe and measure diameter. When the particle shape was not a perfect circle, the major axis was measured as the particle diameter. Moreover, it was confirmed visually whether it was porous or a smooth surface.
The number average particle size was calculated by measuring the particle size of 100 randomly selected particles by the above method and calculating the arithmetic average thereof.
The particle size distribution index indicating the particle size distribution was calculated by substituting the measured value of the particle size obtained by the above method into the following numerical conversion formula.

  Ri: particle size of each particle, n: number of measurements (= 100), Dn: number average particle size, Dv: volume average particle size, PDI: particle size distribution index.

(5) Method of measuring sphericity The sphericity is measured by observing particles with a scanning electron microscope, measuring the short diameter and long diameter of 30 randomly selected particles, and obtaining the measured values below. Substitute into the formula and calculate.

  Note that n is the number of measurements (= 30).

Example 1
A baffle plate is installed in a 1 L titanium autoclave and polylactic acid (L / D = 96/4, Mw (PMMA conversion) 200,000, SP value 23.14 (J / cm ³ ) ^1/2 ) 10. 5 g, 17.5 g of hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) as a polymer different from polylactic acid, ether organic solvent Add 322.0 g of diethylene glycol dimethyl ether (diglyme, boiling point 162 ° C.), heat to 120 ° C., stir and dissolve for 60 minutes at a stirring power of 0.29 kW / m ³ (calculated by the above calculation method) and a stirring speed of 555 rpm. went. The temperature of the system was lowered to 60 ° C., and 350 g of ion-exchanged water was dropped as a poor solvent over 60 minutes using a dropping pump while maintaining the stirring speed. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and 100 g of the obtained suspension is collected, centrifuged, washed with 50 g of ion-exchanged water, and centrifuged for 10 hours at 60 ° C. Drying was performed to obtain 1.5 g of a powdery white solid.
When the obtained powder was observed with a scanning electron microscope, it was in the form of fine particles with a smooth surface, a number average particle size of 0.17 μm, a particle size distribution index of 1.13, and a sphericity of 96. It was fine particles. FIG. 1 shows an observation view of the obtained polylactic acid resin fine particles by a scanning electron microscope.

(Example 2)
A baffle plate is installed in a 1 L titanium autoclave and polylactic acid (L / D = 96/4, Mw (PMMA conversion) 200,000, SP value 23.14 (J / cm ³ ) ^1/2 ) 10. 5 g, 17.5 g of hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) as a polymer different from polylactic acid, ether organic solvent As a result, 322.0 g of diglyme was added, heated to 120 ° C., and stirred and dissolved at a stirring power of 0.026 kW / m ³ (stirring speed 250 rpm) for 60 minutes. The temperature of the system was lowered to 60 ° C., and 350 g of ion-exchanged water was dropped as a poor solvent over 60 minutes using a dropping pump while maintaining the stirring speed. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and 100 g of the obtained suspension is collected, centrifuged, washed with 50 g of ion-exchanged water, and centrifuged for 10 hours at 60 ° C. Drying was performed to obtain 1.4 g of a powdery white solid.
When the obtained powder was observed with a scanning electron microscope, it was in the form of fine particles with a smooth surface, a number average particle size of 0.18 μm, a particle size distribution index of 1.09, and a sphericity of 95. It was fine particles.

(Example 3)
A baffle plate was placed in a 10 L SUS-316 autoclave and polylactic acid (L / D = 96/4, Mw (PMMA conversion) 200,000, SP value 23.14 (J / cm ³ ) ^1/2 ) 105 g, 175 g of hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) as a polymer different from polylactic acid, diglyme as an ether organic solvent 3220 g was added, heated to 120 ° C., and stirred for 60 minutes with a stirring power of 0.88 kW / m ³ (stirring speed: 450 rpm). While reducing the temperature of the system to 60 ° C. and maintaining the stirring speed, 3500 g of ion-exchanged water was dropped as a poor solvent over 60 minutes using a dropping pump. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and 100 g of the obtained suspension is collected, centrifuged, washed with 50 g of ion-exchanged water, and centrifuged for 10 hours at 60 ° C. Drying was performed to obtain 1.4 g of a powdery white solid.
When the obtained powder was observed with a scanning electron microscope, it was a fine particle shape with a smooth surface, a number average particle size of 0.20 μm, a particle size distribution index of 1.06, and a sphericity of 96. It was lactic acid fine particles.

Example 4
A baffle plate was placed in a 10 L SUS-316 autoclave and polylactic acid (L / D = 96/4, Mw (PMMA conversion) 200,000, SP value 23.14 (J / cm ³ ) ^1/2 ) 105 g, 175 g of hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) as a polymer different from polylactic acid, diglyme as an ether organic solvent 3220 g was added, heated to 120 ° C., and stirred for 60 minutes with a stirring power of 0.88 kW / m ³ (stirring speed: 450 rpm). While maintaining the temperature and stirring speed of the system, 3500 g of ion-exchanged water was dropped as a poor solvent over 60 minutes using a dropping pump. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and 100 g of the obtained suspension is collected, centrifuged, washed with 50 g of ion-exchanged water, and centrifuged for 10 hours at 60 ° C. Drying was performed to obtain 1.4 g of a powdery white solid.
When the obtained powder was observed with a scanning electron microscope, it was a fine particle shape with a smooth surface, a number average particle size of 0.31 μm, a particle size distribution index of 1.43, and a sphericity of 95. It was fine particles.

(Example 5)
In a 10 L SUS-316 autoclave, polylactic acid (L / D = 96/4, Mw (PMMA conversion) 200,000, SP value 23.14 (J / cm ³ ) ^1/2 ) 105 g, 175 g of hydroxypropylcellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) as a different polymer, 3220 g of diglyme as an ether organic solvent, and 120 The mixture was heated to ° C. and stirred for 60 minutes at a stirring power of 0.10 kW / m ³ (stirring speed: 279 rpm). While reducing the temperature of the system to 60 ° C. and maintaining the stirring speed, 3500 g of ion-exchanged water was dropped as a poor solvent over 60 minutes using a dropping pump. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and 100 g of the obtained suspension is collected, centrifuged, washed with 50 g of ion-exchanged water, and centrifuged for 10 hours at 60 ° C. Drying was performed to obtain 1.4 g of a powdery white solid.
When the obtained powder was observed with a scanning electron microscope, it was in the form of fine particles with a smooth surface, a number average particle size of 0.21 μm, a particle size distribution index of 1.10, and a sphericity of 96. It was fine particles. FIG. 2 shows an observation view of the obtained polylactic acid resin fine particles by a scanning electron microscope.

(Example 6)
A baffle plate was placed in a 10 L SUS-316 autoclave and polylactic acid (L / D = 96/4, Mw (PMMA conversion) 200,000, SP value 23.14 (J / cm ³ ) ^1/2 ) 105 g, 175 g of hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) as a polymer different from polylactic acid, diglyme as an ether organic solvent 3220 g was added, heated to 120 ° C., and stirred with a stirring power of 0.88 kW / m ³ (stirring speed 450 rpm) for 30 minutes. While reducing the temperature of the system to 60 ° C. and maintaining the stirring speed, 3500 g of ion-exchanged water was dropped as a poor solvent over 60 minutes using a dropping pump. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and 100 g of the obtained suspension is collected, centrifuged, washed with 50 g of ion-exchanged water, and centrifuged for 10 hours at 60 ° C. Drying was performed to obtain 1.4 g of a powdery white solid.
When the obtained powder was observed with a scanning electron microscope, it was in the form of fine particles with a smooth surface, a number average particle size of 0.24 μm, a particle size distribution index of 1.09, and a sphericity of 96. It was fine particles.

(Example 7)
A baffle plate is installed in a 1 L titanium autoclave and polylactic acid (L / D = 96/4, Mw (PMMA conversion) 200,000, SP value 23.14 (J / cm ³ ) ^1/2 ) 10. 5 g, 17.5 g of hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) as a polymer different from polylactic acid, ether organic solvent As a result, 322.0 g of diglyme was added, heated to 120 ° C., and stirred and dissolved for 60 minutes at a stirring power of 0.29 kW / m ³ (stirring speed: 555 rpm). While reducing the temperature of the system to 60 ° C. and maintaining the stirring speed, 350 g of n-nonanol was dropped as a poor solvent over 60 minutes using a dropping pump. After the entire amount of n-nonanol was added, the mixture was further stirred for 30 minutes, and then diglyme was distilled off under reduced pressure at 100 ° C. to prepare an n-nonanol dispersion of polylactic acid resin fine particles.
When the obtained fine particles were observed with a scanning microscope, they were smooth surface fine particle shapes. The number average particle size was 0.38 μm, the particle size distribution index was 1.45, and the sphericity was 94. It was.

(Comparative Example 1)
Polylactic acid-based resin fine particles were produced by the method of Patent Document 8 (International Publication 2012/105140). In a 100 mL four-necked flask, 2.5 g of polylactic acid (L / D = 96/4, Mw (PMMA equivalent) 150,000, SP value 23.14 (J / cm ³ ) ^1/2 ), polymer B Hydroxypropylcellulose (Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) 2.5 g, 45.0 g of diglyme as an ether organic solvent, 80 The mixture was heated to ° C. and stirred with a stirring power of 9.47 × 10 ⁻⁶ kW / m ³ (stirring speed: 450 rpm) until the polymer was completely dissolved. While maintaining the temperature of the system, 50 g of ion-exchanged water as a poor solvent was added dropwise over 61 minutes using a dropping pump while stirring. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and the resulting suspension is filtered, washed with 50 g of ion-exchanged water, and the filtered product is vacuum-dried at 80 ° C. for 10 hours to obtain a powder. 2.3 g of a solid white solid was obtained.
When the obtained powder was observed with a scanning electron microscope, it was in the form of porous fine particles, the number average particle size was 14.0 μm, the particle size distribution index was 1.25, and the sphericity was 93. It was fine particles.

(Comparative Example 2)
Polylactic acid-based resin fine particles were produced by the method of Patent Document 8 (International Publication 2012/105140). In a 100 mL four-necked flask, 1.5 g of polylactic acid (L / D = 98.8 / 1.2, Mw (converted to PMMA) 160,000), and hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., Weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) 2.5 g, 46.0 g of diglyme as an organic solvent was added, heated to 140 ° C., stirring power 9.47 × 10 ⁻⁶ Stirring was performed until the polymer was completely dissolved at kW / m ³ (stirring speed: 450 rpm). While maintaining the temperature of the system, 50 g of ion-exchanged water was dropped as a poor solvent over 122 minutes using a dropping pump while stirring. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and the resulting suspension is filtered, washed with 50 g of ion-exchanged water, and the filtered product is vacuum-dried at 80 ° C. for 10 hours to obtain a powder. 1.3 g of a solid white solid was obtained.
When the obtained powder was observed with a scanning electron microscope, it was in the form of fine particles with a smooth surface, a number average particle size of 1.6 μm, a particle size distribution index of 1.40, and a sphericity of 95. It was fine particles.

(Comparative Example 3)
Polylactic acid-based resin fine particles were produced by the method of Patent Document 8 (International Publication 2012/105140). In a 100 mL four-necked flask, 1.5 g of polylactic acid (L / D = 96/4, Mw (converted to PMMA) 160,000) and hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118) , SP value 29.0 (J / cm ³ ) ^1/2 ) 2.5 g, 46.0 g of diglyme as an organic solvent was added, heated to 60 ° C., stirring power 9.47 × 10 ⁻⁶ kW / m ³ Stirring was performed at a stirring speed of 450 rpm until the polymer was completely dissolved. While maintaining the temperature of the system, 50 g of ion-exchanged water was dropped as a poor solvent over 122 minutes using a dropping pump while stirring. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and the resulting suspension is filtered, washed with 50 g of ion-exchanged water, and the filtered product is vacuum-dried at 80 ° C. for 10 hours to obtain a powder. 1.3 g of a solid white solid was obtained.
When the obtained powder was observed with a scanning electron microscope, it was in the form of fine particles with a smooth surface, a polylactic acid having a number average particle size of 1.8 μm, a particle size distribution index of 1.82, and a sphericity of 97. It was fine particles.

(Comparative Example 4)
Polylactic acid-based resin fine particles were produced by the method of Patent Document 8 (International Publication 2012/105140). In a 100 mL four-necked flask, 2.5 g of polylactic acid (L / D = 88/12, Mw (converted to PMMA) 160,000) and hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118) , SP, 29.0 (J / cm ³ ) ^1/2 ) 2.5 g, 45.0 g of diglyme as an organic solvent, heated to 80 ° C., and stirred power of 9.47 × 10 ⁻⁶ kW / m ³ Stirring was performed at a stirring speed of 450 rpm until the polymer was completely dissolved. While maintaining the system temperature, 50 g of ion-exchanged water was dropped as a poor solvent over 61 minutes using a dropping pump while stirring with a stirrer. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and the resulting suspension is filtered, washed with 50 g of ion-exchanged water, and the filtered product is vacuum-dried at 80 ° C. for 10 hours to obtain a powder. 1.3 g of a solid white solid was obtained.
When the obtained powder was observed with a scanning electron microscope, it was in the form of fine particles with a smooth surface, a number average particle size of 10.2 μm, a particle size distribution index of 1.32 and a sphericity of 94. It was fine particles.

(Comparative Example 5)
A baffle plate was installed in a 1 L titanium autoclave, and polylactic acid (L / D = 96/4, Mw (PMMA conversion) 200,000, SP value 23.14 (J / cm ³ ) ^1/2 ) 17. 5 g, 17.5 g of hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) as a polymer different from polylactic acid, ether organic solvent Then, 315.0 g of diglyme was added, heated to 120 ° C., and stirred for 60 minutes at a stirring power of 0.29 kW / m ³ (stirring speed: 555 rpm). The temperature of the system was lowered to 60 ° C., and 350 g of ion-exchanged water was dropped as a poor solvent over 60 minutes using a dropping pump while maintaining the stirring speed. After all the amount of water has been added, the mixture is further stirred for 30 minutes, and 100 g of the resulting suspension is filtered, washed with 50 g of ion-exchanged water, and the filtered product is vacuum-dried at 60 ° C. for 10 hours. 2.4 g of a powdery white solid was obtained.
When the obtained powder was observed with a scanning electron microscope, it was in the form of porous fine particles, the number average particle size was 1.9 μm, the particle size distribution index was 1.36, and the sphericity was 88. It was fine particles. FIG. 3 shows an observation view of the obtained polylactic acid resin fine particles by a scanning electron microscope.

(Comparative Example 6)
A baffle plate was placed in a 10 L SUS-316 autoclave and polylactic acid (L / D = 96/4, Mw (PMMA conversion) 200,000, SP value 23.14 (J / cm ³ ) ^1/2 ) 105 g, 175 g of hydroxypropyl cellulose (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) as a polymer different from polylactic acid, diglyme as an ether organic solvent 3220 g was added, heated to 120 ° C., and stirred for 60 minutes with a stirring power of 0.88 kW / m ³ (stirring speed: 450 rpm). The temperature of the system was lowered to 60 ° C., and 3500 g of ion-exchanged water was dropped as a poor solvent over 120 minutes using a dropping pump while maintaining the stirring speed. After the entire amount of water has been added, the mixture is further stirred for 30 minutes, and 100 g of the resulting suspension is filtered, washed with 50 g of ion-exchanged water, and the filtrate is vacuum-dried at 60 ° C. for 10 hours. 1.4 g of a powdery white solid was obtained.
When the obtained powder was observed with a scanning electron microscope, it was in the form of fine particles with a smooth surface, a number average particle size of 2.6 μm, a particle size distribution index of 1.19, and a sphericity of 96. It was fine particles.

  The results of Examples and Comparative Examples are shown in Table 1.

According to the present invention, it is possible to obtain polylactic acid resin fine particles having a small particle diameter of 1 μm or less, a true spherical shape and a narrow particle size distribution. Such polylactic acid-based resin fine particles can be used extremely usefully and practically in various industrial applications. Specifically, skin care products additives such as face wash, sunscreen agent, cleansing agent, lotion, milky lotion, beauty essence, cream, cold cream, after shaving lotion, shaving soap, oil blotting paper, matifant agent, Cosmetics such as foundation, funny, watery, mascara, face powder, sky, eyebrow, mascara, eyeline, eye shadow, eye shadow base, nose shadow, lipstick, gloss, cheek, tuna, nail polish, top coat Or its modifiers, shampoos, dry shampoos, conditioners, rinses, rinse-in shampoos, treatments, hair tonics, hair styling agents, hair oils, pomades, hair coloring agents and other hair care product additives, perfumes, eau de cologne, deodora Additives for toiletries, baby powder, toothpaste, mouthwash, lip balm, soap, etc., toner additives, rheology modifiers such as paints, medical diagnostic inspection agents, automotive materials, building materials, etc. Mechanical property improvers for products, mechanical property improvers such as films and fibers, raw materials for resin moldings such as rapid prototyping and rapid manufacturing, flash molding materials, paste resins for plastic sol, powder blocking materials, powders Body fluidity improver, lubricant, rubber compounding agent, abrasive, thickener, filter agent and filter aid, gelling agent, flocculant, paint additive, oil absorbent, mold release agent, plastic film Various modifications such as sheet slipperiness improver, antiblocking agent, gloss modifier, matte finish, light diffusing agent, surface high hardness improver, toughness improver, etc. Agents, Liquid Crystal Display Spacers, Chromatographic Fillers, Cosmetic Foundation Substrates / Additives, Microcapsule Auxiliaries, Drug Delivery Systems, Diagnostic Agents, and Other Medical Materials, Fragrance / Agrochemical Retaining Agents, Chemical Reactions It can be used for catalyst for use and its support, gas adsorbent, sintered material for ceramic processing, standard particles for measurement and analysis, particles for food industry, powder coating material, toner for electrophotographic development, etc. .

Claims (5)

A polylactic acid-based resin (A) and a polymer (B) different from the polylactic acid-based resin are dissolved in an ether-based organic solvent (C), and a solution phase containing the polylactic acid-based resin (A) as a main component and the polylactic acid A dissolution step for forming a system for phase separation into two phases of a solution phase mainly composed of a polymer (B) different from the system resin, an emulsion formation step for stirring the phase separation system to form an emulsion, and Particle precipitation step of precipitating polylactic acid resin fine particles by bringing the poor solvent (α) of the polylactic acid resin having a solubility of the polylactic acid resin (A) smaller than that of the ether organic solvent (C) into contact with the emulsion The method for producing the polylactic acid-based resin fine particles comprises: adding the polylactic acid-based resin to a poor solvent (α) of the polylactic acid-based resin or adding the emulsion to the emulsion. An addition step of bringing the poor solvent (α) of the polylactic acid resin and the emulsion into contact with each other by addition of the relactic acid resin to the poor solvent (α), and the poor solvent (α) of the polylactic acid resin and the emulsion A contact step of precipitating polylactic acid resin fine particles by maintaining the contact state of the polylactic acid resin (A) and the mass ratio of the polymer (B) different from the polylactic acid resin (A) (A / B) is 0.8 or less, the stirring power at the time of forming the emulsion is 0.01 kW / m ³ or more, and the time required for the addition step is 10 minutes or more and 90 minutes or less. A method for producing lactic acid resin fine particles. A boiling point of 100 ° C. or more of the ether-based organic solvent (C), the method of producing polylactic acid resin particles of claim 1. The method for producing polylactic acid-based resin fine particles according to claim 2 , wherein the ether-based organic solvent (C) is diethylene glycol dimethyl ether. The method for producing polylactic acid resin fine particles according to any one of claims 1 to 3 , wherein the polymer (B) different from the polylactic acid resin is hydroxypropylcellulose. The method for producing polylactic acid resin fine particles according to any one of claims 1 to 4 , wherein the poor solvent (α) of the polylactic acid resin is water.

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