JP6365389B2 - Method for producing polylactic acid resin fine particles - Google Patents

Description

  The present invention relates to a method for producing polylactic acid resin fine particles, and more particularly to a method for producing polylactic acid resin fine particles comprising a ketoester compound useful as a substance having a function such as a fragrance.

  The polymer fine particles are fine particles made of a polymer and generally have a diameter ranging from several tens of nm to several hundreds of μm.

  Unlike polymer molded products such as films, fibers, injection molded products, and extrusion molded products, polymer fine particles are used to improve and modify various materials by taking advantage of the large specific surface area and the fine structure of the fine particles. Yes. Major applications include cosmetic modifiers, rheology modifiers such as toner additives and paints, medical diagnostic inspection agents, additives to molded articles such as automotive materials and building materials. In particular, in recent years, it has come to be used as a raw material for rapid prototyping and rapid manufacturing (3D printer), which are methods for producing tailor-made molded products in combination with high-precision laser processing technology.

  Aliphatic polyester resin fine particles, as is known in the examples of polyglycolic acid and polylactic acid, are polyesters that are easy to make from compounds derived from non-petroleum raw materials, and are relatively highly biodegradable polymers. It is expected to be used as a material with low environmental impact.

  Various methods for obtaining aliphatic polyester resin fine particles are known, but in general, mechanical pulverization methods represented by freeze pulverization and the like (see Patent Documents 1 and 2), which are dissolved in a solvent at high temperature. Solvent precipitation method (see Patent Documents 3 and 4), which is precipitated by cooling or precipitation by adding a poor solvent after dissolving in a solvent, and a twin screw extruder as represented by polylactic acid, etc. In the mixing machine, an aliphatic polyester resin and an incompatible resin were mixed to form a resin composition having the aliphatic polyester resin as a dispersed phase and the aliphatic polyester resin and an incompatible resin as a continuous phase. Thereafter, it is known that it can be produced by a melt-kneading method (see Patent Documents 5 and 6) for obtaining aliphatic polyester resin fine particles by removing an incompatible resin.

  In recent years, among aliphatic polyester resins, a microparticulation technique characterized by oil absorption performance using a polylactic acid resin having biodegradability has been developed (see Patent Document 7).

  However, additives with higher functionality have been demanded from various fields including cosmetics and paints, and in particular, particles containing aroma components have been demanded.

  The above-described prior art has no specific disclosure of adding a fragrance, and such particles and a method for producing the same have been desired.

JP 2000-7789 A JP 2001-288273 A JP 20052302 A JP 2009-242728 A JP 2004-269865 A Japanese Patent Laid-Open No. 2005-200663 International Publication No. 2012/105140

  An object of the present invention is to provide a method for producing polylactic acid resin fine particles having excellent oil absorption and hydrophilicity and having a pore suitable for cosmetic foundations, paint thickeners, and the like. An object of the present invention is to provide a method for producing polylactic acid resin fine particles having a narrow distribution and excellent powdery handling property.

In order to solve the above problems, the present inventors have intensively studied and as a result, have reached the following invention.
( 1 ) As a polymer different from (A) polylactic acid resin and (B) polylactic acid resin, at least one selected from polyvinyl pyrrolidone, hydroxypropyl cellulose, polyvinyl alcohol, polyethylene oxide, and polyethylene glycol; C) In a system in which an organic solvent containing a ketoester compound is dissolved and mixed, and phase-separated into two phases, a solution phase mainly composed of polylactic acid resin and a solution phase mainly composed of a polymer different from polylactic acid resin. After forming the emulsion, the polylactic acid resin fine particles having a step of precipitating the polylactic acid resin fine particles by contacting at least one selected from ethanol, methanol and water as a poor solvent for the polylactic acid resin Manufacturing method.
( 2 ) The method for producing the aliphatic polyester resin fine particles as described above, wherein the method of forming an emulsion gives a shearing force.

Since the polylactic acid resin fine particles obtained by the method for producing the polylactic acid resin fine particles of the present invention have a porous shape and a high specific surface area, they are excellent in oil absorption and use a ketoester compound. In addition, the polylactic acid resin fine particles obtained by the production method of the present invention are characterized by high sustained release performance. From these characteristics, according to the present invention, polylactic acid resin fine particles suitable for applications such as cosmetics and paint additives can be obtained.

The polylactic acid resin fine particles obtained by the method for producing the polylactic acid resin fine particles of the present invention have remarkably high oil absorbency, and in a preferred form, the particle size distribution is narrow, and the fluidity and handleability are excellent. Furthermore, from these points, cosmetic materials such as foundations, lipsticks, and scrub agents for male cosmetics, gloss additives, paint additives such as matting finishes, light diffusing agents, plastic sol paste resins, 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 modifiers such as sheet slipperiness improver, antiblocking agent, high surface hardness improver, toughness improver, liquid crystal display spacer, chromatographic filler, cosmetic foundation substrate / additive, microcapsule Aids, medical materials such as drug delivery systems / diagnostics, fragrance / pesticide retention agents, catalysts for chemical reactions and their supports, gas adsorbents, Ceramic machining sintered material, standard particles for measurement and analysis can be used particles for food industry, powder coating material, and the toner and the like for electrophotographic development.

FIG. 1 is a scanning electron micrograph in place of a drawing of the polylactic acid resin fine particles produced in Example 1. FIG. 2 is a drawing-substitute scanning electron micrograph in which the polylactic acid resin fine particles produced in Example 1 are enlarged. FIG. 3 is a scanning electron micrograph in place of a drawing of the polylactic acid resin fine particles produced in Example 2. FIG. 4 is a drawing-substituting scanning electron micrograph in which the polylactic acid resin fine particles produced in Example 2 are enlarged. FIG. 5 is a scanning electron micrograph in place of a drawing of the polylactic acid resin fine particles produced in Example 3. FIG. 6 is a drawing-substitute scanning electron micrograph in which the polylactic acid resin fine particles produced in Example 3 are enlarged. FIG. 7 is a scanning electron micrograph in place of a drawing of the polylactic acid resin fine particles produced in Example 4. FIG. 8 is a scanning-type scanning electron micrograph in which the polylactic acid resin fine particles produced in Example 4 are enlarged. FIG. 9 is a scanning electron micrograph in place of a drawing of the polylactic acid resin fine particles produced in Example 5. FIG. 10 is a drawing-substitute scanning electron micrograph in which the polylactic acid resin fine particles produced in Example 5 are enlarged. FIG. 11 is a scanning electron micrograph in place of a drawing of the polylactic acid resin fine particles produced in Example 6. FIG. 12 is a drawing-substitute scanning electron micrograph in which the polylactic acid resin fine particles produced in Example 6 are enlarged. FIG. 13 is a scanning electron micrograph in place of a drawing of the polylactic acid resin fine particles produced in Example 7. FIG. 14 is a drawing-substituting scanning electron micrograph in which the polylactic acid resin fine particles produced in Example 7 are enlarged. FIG. 15 is a drawing-substituting scanning electron micrograph of the polylactic acid resin fine particles produced in Example 8. FIG. 16 is a drawing-substituting scanning electron micrograph in which the polylactic acid resin fine particles produced in Example 8 are enlarged.

Next, the polylactic acid resin fine particles obtained by the method for producing polylactic acid resin fine particles of the present invention and the production method thereof will be described in detail.

The polylactic acid resin fine particles obtained by the method for producing the polylactic acid resin fine particles of the present invention have a number average particle size of 1 to 90 μm, a particle size distribution index of 1 to 3, and aliphatic polyester resin fine particles comprising a ketoester compound. It is.

  The ketoester compound used in the present invention refers to a compound further having a carbonyl group in the molecule of the ester compound, such as α-ketoester, β-ketoester, γ-ketoester, α-diester and β-diester. Point to.

  In general, ketoester compounds are known to be aromatic components, and are particularly known to be used as perfumes.

  Specifically, as ketoester compounds, methyl acetoacetate, ethyl acetoacetate, isobutyl acetoacetate, tertbutyl acetoacetate, allyl acetoacetate, acetoacetate (2-methoxyethyl), ethyl 2-methylacetoacetate, ethyl 2-ethylacetoacetate , Methyl propionyl acetate, ethyl propionyl acetate, ethyl butyryl acetate, ethyl isobutyryl acetate, methyl 4,4-dimethyl-3-oxopentanoate, methyl 4,4-dimethoxy-3-oxovalerate, diethyl 4-oxopimelate, 2- Ethyl hexyl acetoacetate, ethyl benzylacetoacetate, methyl levulinate, ethyl levulinate, butyl levulinate, isoamyl levulinate, methyl pyruvate, ethyl pyruvate, methyl dihydrojasmonate, 3-methyl-2-oxobuta Diethyl esters of malonic acid such as ethyl acid, ethyl 4-acetylbutanoate, 4-acetoxy-2-butanone, dimethyl malonate and diethyl malonate, dimethyl succinate and dialkyl esters of succinic acid such as diethyl succinate, dimethyl fumarate, Dialkyl fumarate such as diethyl fumarate, dialkyl maleate such as dimethyl maleate and diethyl maleate, itaconic acid dialkyl esters such as dimethyl itaconate and diethyl itaconate, dimethyl cyclohexanedicarboxylate and diethyl cyclohexanedicarboxylate And cyclohexanedicarboxylic acid diesters.

  In addition, the ketoester compound is preferably a liquid at normal temperature from the viewpoint of ease of use in the process of producing particles described later. From this point of view, the ketoester compounds include methyl acetoacetate, ethyl acetoacetate, ethyl 2-hexylacetoacetate, ethyl benzylacetoacetate, methyl levulinate, ethyl levulinate, butyl levulinate, isoamyl levulinate, methyl pyruvate, pyruvin Ethyl acid, methyl dihydrojasmonate and dimethyl malonate and diethyl malonate are preferred, and ethyl acetoacetate, methyl acetoacetate and ethyl 2-hexylacetoacetate are more preferred.

The polylactic acid resin in the present invention is obtained by connecting non-aromatic hydrocarbon groups with an ester bond. The ester bond is a condensation bond of a hydroxyl group and a carboxyl group, and refers to an ester bond or a carbonate bond.

Specific examples of the polylactic acid resin, polylactic acid (L- (S) - lactic acid and / or D-(R) - to finger polymer whose main constituent lactic acid) and the like.

These polylactic acid resins can contain other copolymer components in addition to the respective monomers. Examples of such other copolymer component units include polycarboxylic 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- Polyvalent carboxylic acids such as tetrabutylphosphonium sulfoisophthalic acid, ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyling Cole, Glycerin, Pentaerythritol, Bisphenol A, Aromatic polyhydric alcohol in which ethylene oxide is added to bisphenol, polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, glycolic acid, Hydroxycarboxylic acids such as 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, hydroxybenzoic acid, and glycolide, ε-caprolactone glycolide, ε-caprolactone, β-propiolactone, δ -Units generated from lactones such as butyrolactone, β- or γ-butyrolactone, pivalolactone and δ-valerolactone.

Such copolymer units are preferably contained in the polylactic acid resin in an amount of 30% by weight or less, more preferably 20% by weight or less, further preferably 10% by weight or less, and most preferably 5% by weight or less. If it has the effect of the present invention, it can contain some aromatic hydrocarbon groups.

Among the polylactic acid resins used in the present invention, when the monomer unit is an optical isomer, it is preferable to use a polylactic acid resin using a monomer having high optical purity from the viewpoint of heat resistance. That is, it is preferable that 80% or more of the R isomer or 80% or more of the S isomer is included in the monomer of the polylactic acid resin, and 90% or more of the R isomer or 90% or more of the S isomer is included. More preferably, the R isomer is contained at 95% or more, or the S isomer is contained at 95% or more, and the R isomer is contained at 98% or more, or the S isomer is contained at 98% or more. . Moreover, the upper limit of content of R body or S body is 100% normally.

Further, among the polylactic acid resins used in the present invention , when the monomer unit is an optical isomer, a stereocomplex represented by polylactic acid can be used in terms of heat resistance and moldability. .

  As a method for forming a stereocomplex, when polylactic acid is described as an example, L-form is 90% or more, preferably 95%, more preferably 98% or more poly-L-lactic acid, and D-form in terms of heat resistance. 90% or more, preferably 95%, more preferably 98% or more of poly-D-lactic acid is melted and mixed using a technique such as mixing or mixing as a solution. it can. In addition, as another method, a method of forming a block copolymer composed of a poly-L-lactic acid segment and a poly-D-lactic acid segment can also be mentioned, and a polylactic acid stereocomplex can be easily formed. A method of preparing a block copolymer comprising a poly-L-lactic acid segment and a poly-D-lactic acid segment is preferred. In the present invention, the polylactic acid stereocomplex may be used alone, or the polylactic acid stereocomplex and poly-L-lactic acid or poly-D-lactic acid may be used in combination.

As a method for producing the polylactic acid resin, a known polymerization method can be used, such as condensation reaction of aliphatic hydroxycarboxylic acid or aliphatic hydroxyester, ring-opening polymerization reaction of aliphatic lactone, aliphatic diol and aliphatic dicarboxylic acid. It can be produced from a condensation polymerization reaction with an acid or an aliphatic diester.

The molecular weight or molecular weight distribution of the polylactic acid resin is not particularly limited as long as it is substantially soluble, but it is easy to maintain the particle structure and improves the hydrolysis resistance. Is preferably 10,000 or more, more preferably 20,000 or more, even more preferably 30,000 or more, particularly preferably 50,000 or more, particularly preferably 70,000 or more, and most preferably 10 It should be 10,000 or more. The upper limit is not particularly limited, but if specified, it is 1,000,000 or less, more preferably 800,000 or less, further preferably 600,000 or less, particularly preferably 400,000 or less, and particularly preferably 300,000 or less. Or less, and most preferably 200,000 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.

In the present invention, the melting point of the polylactic acid resin is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, further preferably 150 ° C. or higher, taking into consideration the normal use environment.

The number average particle size of the polylactic acid resin fine particles in the present invention is generally 1000μm or less, at 100μm or less according to a preferred embodiment, more according to a preferred embodiment, it is 90μm or less, be 50μm or less According to a further preferred embodiment According to a particularly preferable aspect, it is 30 μm or less, according to a remarkably preferable aspect, it is 20 μm or less, and according to a most preferable aspect, it is 15 μm or less. The lower limit of the number average particle diameter is usually 50 nm or more, 100 nm or more according to a preferred embodiment, 500 nm or more according to a more preferred embodiment, 1 μm or more according to a more preferred embodiment, and a particularly preferred embodiment. According to a particularly preferable aspect, it is 3 micrometers or more, and according to the most preferable aspect, it is possible to manufacture a thing of 5 micrometers or more.

  The particle size distribution is 3 or less as a particle size distribution index, 2.5 or less according to a preferred embodiment, 2 or less according to a more preferred embodiment, and 1.8 or less according to a more preferred embodiment. According to a particularly preferred embodiment, it is 1.5 or less, and according to a most preferred embodiment, it is possible to produce a product of 1.2 or less. The preferred lower limit of the particle size distribution is 1.

Polylactic acid resin fine particles in the present invention, the shape is porous. Therefore, it is measured using a laser diffraction / light scattering type particle size distribution meter (Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd.), which can be measured with higher accuracy than the number average particle diameter calculated based on the morphology of the particles observed in the micrograph. the number average particle diameter of that, a number average particle size of the polylactic acid resin fine particles of the present invention.

More specifically, the number average particle diameter of the polylactic acid resin fine particles is determined by the wet laser diffraction / scattering method (manufactured by Nikkiso Co., Ltd., model: Microtrac MT3300EXII), with the dispersion medium for measurement as water, and the refractive index of the substance. The number average particle diameter measured with a polylactic acid resin fine particle dispersion in which aliphatic polyester resin fine particles are predispersed in ion-exchanged water with a refractive index of 1.60 and a dispersion medium set to 1.333 is shown. The particle size distribution index representing the particle size distribution is a value obtained by dividing the volume average particle size measured by the particle size distribution meter by the number average particle size.

The polylactic acid resin fine particles obtained by the production method of the present invention are characterized by containing the ketoester compound. As described above, the ketoester compound is a chemical substance having functionality such as a fragrance, and so far, polylactic acid resin fine particles containing the ketoester compound have not been known. The polylactic acid resin fine particles obtained by the production method of the present invention are more useful than the conventional aliphatic polyester resin particles as highly functional polymer fine particles having a function of having an aroma.

Content of keto ester contained in the polylactic acid resin fine particles in the invention is preferably an amount that serves as an aroma component, depending on the environment in which the polylactic acid resin fine particles are used, polylactic acid resin fine particles 1 ppb or more, preferably 10 ppb or more, more preferably 100 ppb or more, still more preferably 1 ppm or more, and particularly preferably 100 ppm or more.

  The upper limit is not particularly limited, but is generally 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and particularly preferably 2% by mass or less. Preferably it is 1 mass% or less (10000 ppm or less).

The content of the ketoester compound in the polylactic acid resin fine particles can be confirmed using gas chromatography.

The polylactic acid resin fine particles comprising a ketoester compound obtained by the production method of the present invention are different from known microcapsule resin particles, that is, those having a form in which a liquid substance is coated with a polymer, The compound is considered to be a solid solution in the amorphous phase of the polylactic acid resin particles.

A more preferable form of the polylactic acid resin fine particles obtained by the production method of the present invention is that it is porous. The polylactic acid resin fine particles obtained by the production method described later have a specific surface area larger than that of conventionally known aliphatic polyester particles because a state in which polymer crystalline structures are gathered is formed. In some cases, a scaly polymer crystal structure may be observed. As a result, the oil absorption of linseed oil, which is an index indicating lipophilicity, is increased, and a material that is highly practical in the field of cosmetics and paints is created.

The lower limit of the oil absorption amount of the polylactic acid resin fine particles obtained by the production method of the present invention is 90 ml / 100 g, preferably 100 ml / 100 g, more preferably 200 ml / 100 g, still more preferably 300 ml / 100 g. Yes, particularly preferably 400 ml / 100 g or more, and particularly preferably 500 ml / 100 g. Further, the higher the oil absorption, the better. The upper limit is not particularly defined, but it is actually 1000 ml / 100 g and 900 ml / 100 g.

If the oil absorption amount of linseed oil is in this range, particles having a high oil absorption amount and particles having improved release characteristics of the ketoester compound as an aroma component can be obtained, and can be suitably used as an additive for cosmetics and paints. Although the detailed mechanism for the formation of scaly tissue has not been fully clarified, the results of powder X-ray structural analysis of polylactic acid fine particles, which are representative examples of polylactic acid resin fine particles obtained by the production method of the present invention The diffraction angle 2θ typically has a crystal structure having peaks at 16.62 °, 18.92 °, and 22.20 °, and was found to have a β-type crystal structure. This is considered to have facilitated the formation of scaly tissue and led to improved oil absorption.

The shape of the polylactic acid resin fine particles in the present invention is preferably close to a true sphere.

The sphericity of the polylactic acid resin fine particles used in the present invention is preferably 60 or more, more preferably 70 or more, still more preferably 80 or more, and particularly preferably 90 or more.

  When the sphericity is in the above range, the texture such as slipperiness is improved, and the viscosity can be easily controlled when added to a paint or the like.

  The sphericity is calculated according to the following formula (1) from the average of 30 arbitrary particles by observing particles with a scanning electron microscope, measuring the short diameter and the long diameter.

Here, n is 30 measurements.

As a method for producing the polylactic acid resin fine particles of the present invention, the present inventors have described "(A) a polylactic acid resin and (B) a polymer different from the polylactic acid resin, and (C) an organic solvent containing a ketoester compound. was dissolved mixture, (a) and solution phase composed mainly of polylactic acid resin, in a system which phase separated into two phases of solution phase composed mainly of different polymer and (B) a polylactic acid resin, forming an emulsion after, by contacting a poor solvent of the polylactic acid resin, discloses a production method "for precipitating polylactic acid resin particles.

The different polymer and (B) a polylactic acid resin, thermoplastic resins and the like, dissolved in a poor solvent for the organic solvent and (A) polylactic acid resin dissolving (A) the polylactic acid resin used in the present invention Among them, those that dissolve in the above-mentioned organic solvents, and those that dissolve in alcohol solvents or water are more preferable in terms of industrial handleability, and are further soluble in organic solvents, and are methanol, ethanol, or water. Those which are soluble in the aqueous solution are particularly preferably used.

(B) If a polymer different from the aliphatic polyester resin is specifically exemplified, poly (vinyl alcohol) (which may be fully saponified or partially saponified poly (vinyl alcohol)), poly (vinyl alcohol) may be used. Vinyl alcohol-ethylene) copolymer (which may be a fully saponified or partially saponified poly (vinyl alcohol-ethylene) copolymer), polyvinylpyrrolidone, polyethylene oxide, poly (ethylene glycol ), etc. Can be mentioned.

(B) The molecular weight of the polymer different from the polylactic acid resin is preferably 1,000 or more as a weight average molecular weight, more preferably 2,000 or more, still more preferably 3,000 or more, particularly preferably 5, 000 or more, particularly preferably 7,000 or more, and most preferably 10,000 or more. The upper limit is not particularly limited, but the weight average molecular weight is preferably 10,000,000 or less, more preferably 5,000,000 or less, still more preferably 3,000,000 or less, and particularly preferably 2,000. , 1,000 or less, particularly preferably 1,500,000 or less, and most preferably 1,000,000 or less.

  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.

  When measurement with water is not possible, dimethylformamide is used. When measurement is still impossible, tetrahydrofuran is used. When measurement is not possible, hexafluoroisopropanol can be used.

Preparation of polylactic acid resin fine particles of the present invention, (A) and the polylactic acid resin (B) different polymer and the polylactic acid resin (C) an organic solvent containing a keto ester compound (hereinafter simply "(C) Organic solvent" And (B) a polylactic acid resin. (A) a solution phase mainly composed of a polylactic acid resin (hereinafter sometimes referred to as a polylactic acid resin solution phase) and (B) a polylactic acid resin After forming an emulsion in a system that separates into two phases of a solution phase (hereinafter, also referred to as a polymer B solution phase) containing a different polymer as a main component, (A) the poor solvent of the polylactic acid resin is converted into an emulsion (A) A method for producing polymer fine particles characterized in that the polylactic acid resin fine particles are precipitated by contacting with a polymer.

In the above, “(A) polylactic acid resin and (B) a polymer different from polylactic acid resin and (C) an organic solvent containing a ketoester compound are dissolved and mixed, and (A) a solution phase containing polylactic acid resin as a main component. And (B) a system that phase-separates into two solution phases mainly composed of a polymer different from polylactic acid resin ”means that (A) polylactic acid resin and (B) polylactic acid resin are different polymers ( C) A system that, when mixed with an organic solvent, is divided into two phases: (A) a solution phase mainly containing polylactic acid resin and (B) a solution phase mainly containing polylactic acid resin.

In the above, whether or not “(A) polylactic acid resin” or “(B) polymer different from polylactic acid resin” is dissolved depends on the temperature at which the present invention is carried out, that is, (A) polylactic acid resin and ( B) At a temperature at which a polymer different from the polylactic acid resin is subjected to two-phase separation, the determination is made based on whether or not the polymer dissolves in an organic solvent containing (C) a ketoester compound in an amount of more than 1% by mass.

  By using such a phase-separating system, it is possible to mix and emulsify under a phase-separating condition to form an emulsion.

In this case, (C) the organic solvent is generally distributed into both the polylactic acid resin solution phase and the polymer B solution phase, depending on the organic solvent used, the temperature, and the blending amount.

Therefore, in the organic solvent (C), the keto ester compound is preferably 90% by mass or more, more preferably 95% by mass or more, and most preferably 100% by mass. With such an organic solvent (C), the ketoester compound when separated into two phases of (A) a solution phase mainly containing a polylactic acid resin and (B) a solution phase mainly containing a polymer different from the polylactic acid resin. This eliminates the need to adjust the distribution ratio, and is convenient.

The emulsion, the polylactic acid resin solution phase is the dispersed phase, different polymer solution phase becomes the continuous phase and the polylactic acid resin, and to this emulsion, by contacting the poor solvent of the polylactic acid resin, in an emulsion polylactic acid resin is precipitated from the polylactic acid resin solution phase, it is possible to obtain a polymer composed particulate polylactic acid resin and ketoesters.

In the present invention, in order to obtain porous polylactic acid resin fine particles, (C) an organic solvent for dissolving a polymer different from (A) polylactic acid resin and (B) polylactic acid resin is not particularly limited. However, polar solvents, ether solvents, β-diketone compounds, keto ester compounds, and the like are preferable from the viewpoint that porous particles are easily obtained.

(A) for the case of polylactic acid resins is their technology in Patent Document 7 discloses, in recent years, a higher porosity of the particles has been required. In order to obtain particles with higher porosity, it is necessary to balance the particle precipitation process and the polymer crystallization process, and therefore the selection of the solvent is important. If a solvent with too high solubility is used, the solvent remains inside the fine particles after the fine particles are precipitated, and fusion between particles is likely to occur during solid-liquid separation such as filtration, resulting in a large particle size distribution. Tend to be. However, the use of a polar solvent, an ether solvent, a β-diketone compound, or a ketoester compound is extremely advantageous because it is difficult to cause fusion, and particles having a narrow particle size distribution and easy handling can be obtained.

  Specifically, in the organic solvent (C), polar solvents other than keto ester compounds include N-methylpyrrolidone, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, propylene carbonate, trimethyl phosphoric acid, Examples include 1,3-dimethyl-2-imidazolidinone and sulfolane.

  Examples of ether solvents include aliphatic chain ethers such as dimethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, dipentyl ether, dihexyl ether, dioctyl ether, diisoamyl ether, tert-amyl methyl ether, tert- Butyl ethyl ether, butyl methyl ether, butyl ethyl ether, 1-methoxyethane (monoglyme), 1-ethoxyethane, 1,2-dimethoxyethane (diglyme), ethylene glycol diethyl ether, 2-methoxyethyl ether, di (ethylene glycol) ) Diethyl ether, di (ethylene glycol) dibutyl ether and triethylene glycol dimethyl ether are exemplified.

  Examples of the aliphatic cyclic ether include tetrahydrofuran, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2,2,5,5-tetramethylhydrofuran, 2,3-dihydrofuran, 2,5-dihydrofuran, Tetrahydropyran, 3-methyltetrahydropyran, 1,3-dioxolane, 2-methyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, 2-n -Butyl-1,3-dioxolane, 2,2-di-n-propyl-1,3-dioxolane, 2-ethyl-2-methyl-1,3-dioxolane, 2,2-di-n-propyl-4 -Methyl-1,3-dioxolane, 2,2-diisopropyl-4-methyl-1,3-dioxolane, 2-n-butyl-4-methyl 1,3-dioxolane, 2-n-propyl-4-methyl-1,3-dioxolane, 2-methyl-2-isobutyl-4-methyl-1,3-dioxolane, 2-n-butyl-4-ethyl- 1,3-dioxolane, 2,2-di-n-propyl-4-methyl-1,3-dioxolane, 1,3-dioxane, 4-methyl-1,3-dioxane, 2-n-butyl-4- Examples include methyl-1,3-dioxane, 1,4-dioxane, 2-n-propyl-1,3-dioxepane and 1,3,5-trioxane.

  Examples of the aromatic ether include anisole, phenetole (ethylphenol), diphenyl ether, 3-phenoxytoluene, p-tolyl ether, 1,3-diphenoxybenzene, 1,2-diphenoxyethane, and the like.

  Of these, dipropyl ether, diisopropyl ether, dibutyl ether, 1-ethoxyethane, 1,2-dimethoxy are taken into consideration from the viewpoint of industrial ease of use, economical viewpoint, and easy production of porous particles. Ethane (diglyme), ethylene glycol diethyl ether, 2-methoxyethyl ether, di (ethylene glycol) diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 2-methyl-1,3-dioxolane, 1,4-dioxane and anisole are preferred, more preferably 1-ethoxyethane, 1,2-dimethoxyethane (diglyme), ethylene glycol diethyl ether, 2-methoxyethyl ether, di (ethylene glycol) diethyl. Ether, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 2-methyl-1,3-dioxolane, 1,4-dioxane, more preferably tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 2-methyl-1,3-dioxolane and 1,4-dioxane, particularly preferably tetrahydrofuran, tetrahydropyran and 1,3-dioxolane.

  (C) The ketoester compound contained in the organic solvent is as described above. The keto ester compound is preferably a liquid at the temperature at which the particles are formed, and a liquid keto ester compound is particularly preferably used at a temperature of 25 ° C. Examples of such ketoester compounds include methyl acetoacetate, ethyl acetoacetate, isobutyl acetoacetate, methyl pyruvate, ethyl pyruvate, ethyl 4-acetylbutanoate, 4-acetoxy-2-butanone, methyl levulinate, levulin Examples include ethyl acid and dimethyl maleate and diethyl maleate.

  Examples of the β-diketone compound include 2,4-pentanedione, 3-methyl-2,4-pentanedione, 3-ethyl-2,4-pentanedione, 3-chloro-2,4-pentanedione, , 1,1-trifluoro-2,4-pentanedione, 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, 2,2,6,6-tetramethyl-3, 5-heptanedione, 2-acetylcyclohexanone, 1,3-cyclopentanedione, 2-methyl-1,3-cyclopentanedione, 1,3-cyclohexanedione, 2-methyl-1,3-cyclohexanedione, 5- Methyl-1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1-benzoylacetone, dibenzoylmethane, 1- (2-hydroxyphenol Le) -3-phenyl-1,3-propanediol and 4,4,4-trifluoro-1-phenyl-1,3-butanedione, and the like.

  The ketoester compound is the compound described above. The ketoester compound is preferably liquid at the temperature at which the particles are formed, and is particularly liquid even at a temperature of 25 ° C. By doing in this way, ketoester compound itself can be used as (C) organic solvent.

  Ketoester compounds include methyl acetoacetate, ethyl acetoacetate, isobutyl acetoacetate, methyl pyruvate, ethyl pyruvate, ethyl 4-acetylbutanoate, 4-acetoxy-2-butanone, methyl levulinate, ethyl levulinate and maleic acid Examples include dimethyl and diethyl maleate.

  Each of the organic solvents other than the ketoester compound and the ketoester compound can contain a plurality of types. Moreover, (C) organic solvent can be comprised only with a ketoester compound.

  (C) The content of the ketoester compound in the organic solvent is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, and still more preferably 0.01% by mass as the preferable content. That's it. From the viewpoint of long-term sustained release of aroma, it is particularly preferably 0.1% by mass or more, and particularly preferably 1% by mass or more. Further, the upper limit as the content is preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably 100% by mass.

Before mixing (A) polylactic acid resin and (B) polymer different from polylactic acid resin, ketoester and other organic solvent can be mixed in advance to prepare (C) organic solvent. Moreover, a polymer different from (A) polylactic acid resin and (B) polylactic acid resin can be mixed.

From the viewpoint of obtaining particles having a relatively small particle size and a small particle size distribution, it is preferable that (C) the organic solvent comprises only a keto ester or one other organic solvent. Further, since the types of contents are reduced, there is a feature that the separation process at the time of recycling the used solvent is simplified. It is preferably an organic solvent that dissolves both (A) polylactic acid resin and (B) a polymer different from polylactic acid resin.

In the present invention, the poor solvent for the polylactic acid resin (A) to be brought into contact with the emulsion means a solvent that does not dissolve the (A) polylactic acid resin. When the solvent is not dissolved, the solubility of the (A) polylactic acid resin in the poor solvent is 1% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.1% by mass or less. is there.

The method of manufacturing a polylactic acid resin particles of the present invention, and (A) is used a poor solvent of the polylactic acid resin, but as such a poor solvent is a poor solvent for (A) polylactic acid resin, and (B) a polylactic acid resin Is preferably a solvent that dissolves different polymers. Thereby, the polymer fine particle comprised by (A) polylactic acid resin can be precipitated efficiently. Moreover, it is preferable that the solvent which dissolves the polymer different from (A) polylactic acid resin and (B) polylactic acid resin and the poor solvent of (A) polylactic acid resin are a solvent which mixes uniformly.

Poor solvent used in the present invention, the type of reference is (A) polylactic acid resin, varies depending on the type of both different polymers are further used and (A) the polylactic acid resin (B) a polylactic acid resin. Specific examples of the poor solvent include pentane, hexane, heptane, octane, nonane, n-decane, n-dodecane, n-tridecane, cyclohexane, cyclopentane and other aliphatic hydrocarbon solvents, benzene, toluene, Examples thereof include aromatic hydrocarbon solvents such as xylene, alcohol solvents such as methanol, ethanol and 1-propanol-2-propanol, and a solvent selected from at least one of water.

As the poor solvent, viewpoint et be efficiently particles the (A) polylactic acid resin, ethanol, methanol and water is used.

In the present invention, (A) a polylactic acid resin and (B) a polymer different from the polylactic acid resin, (C) an organic solvent for dissolving them, and (A) a poor solvent for the polylactic acid resin are appropriately selected and combined. Thus, (A) polylactic acid resin can be efficiently precipitated to obtain polymer fine particles.

A liquid obtained by mixing and dissolving (A) a polylactic acid resin and (B) a polymer different from the polylactic acid resin, and an organic solvent for dissolving them, and (A) a solution phase mainly composed of a polylactic acid resin, and (B ) It is necessary to phase-separate into two phases of a solution phase mainly composed of a polymer different from polylactic acid resin.

The conditions for generating the two-phase separation state are (A) polylactic acid resin and (B) polylactic acid resin different types of polymer, (A) polylactic acid resin and (B) polylactic acid resin different molecular weight It varies depending on the kind of organic solvent, (A) polylactic acid resin, (B) concentration of polymer different from polylactic acid resin, temperature at which the invention is to be carried out, and pressure.

In order to obtain conditions that are likely to result in a phase-separated state, the difference in solubility parameters (hereinafter also referred to as SP values) of polymers different from (A) polylactic acid resin and (B) polylactic acid resin is separated. Is preferable.

At this time, the difference in SP value is 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, and particularly preferably 8 (J / cm ³ ) ^1/2 or more. When the SP value is within this range, phase separation is easily performed.

If both (A) polylactic acid resin and (B) polylactic acid resin are soluble in an organic solvent, the upper limit of the difference in SP value is preferably 20 (J / cm ³ ) ^1/2 , More preferably, it is 15 (J / cm < ³ >) ^<1/2 >, More preferably, it is 10 (J / cm < ³ >) ^<1/2 >.

  Here, the SP value is calculated based on the Fedor's estimation method, and is calculated based on the cohesive energy density and the molar molecular volume (hereinafter also referred to as a calculation method). ("SP Value Basics / Applications and Calculation Methods" by Hideki Yamamoto, Information Organization Co., Ltd., published on March 31, 2005).

  When the calculation cannot be performed by this method, the SP value is calculated by an experimental method based on the determination of whether or not the solubility parameter is dissolved in a known solvent (hereinafter also referred to as the experimental method), and is used as a substitute. ("Polymer Handbook Fourth Edition" by J. Brand, published in 1998 by Wiley).

To select the conditions that cause the phase separation state, (A) the polylactic acid resin and (B) different polymer than the polylactic acid resin, and observation of the state of changing the ratio of the three components of organic solvent to dissolve them Can be identified by a three-component phase diagram that can be created by a simple preliminary experiment.

To create a phase diagram, (A) polylactic acid resin and (B) polylactic acid resin and a different polymer and solvent are mixed and dissolved at a certain ratio, and it is determined whether or not an interface is formed when left standing. At least 3 or more types, preferably 5 or more types, more preferably 10 or more types, and determine the conditions for phase separation by distinguishing the two-phase separation region and the one-phase region. Can do.

At this time, in order to determine whether or not it is in a phase-separated state, a polymer different from (A) polylactic acid resin and (B) polylactic acid resin is arbitrarily selected at a temperature and pressure at which the present invention is to be carried out. (A) Polylactic acid resin and (B) Polylactic acid resin are adjusted to a different polymer and solvent ratio, and then (A) polylactic acid resin and (B) polylactic acid resin are completely dissolved, After dissolution, the mixture is sufficiently stirred, for example, left for 3 days, and it is confirmed whether or not phase separation is performed macroscopically. However, when the emulsion is phase-separated but sufficiently stable, macroscopic phase separation may not occur even if it is left for 3 days. In that case, phase separation is discriminated based on whether or not the phase separation is microscopically using an optical microscope or a phase contrast microscope.

Phase separation, in an organic solvent (A) polylactic acid resin mainly (A) a polylactic acid resin solution phase, (B) separating the polymer B solution phase composed mainly of different polymer than the polylactic acid resin Formed by. In this case, (A) the polylactic acid resin solution phase is a phase which is largely dispensed (A) polylactic acid resin, different polymer solution phase and the polylactic acid resin have different polymer and (B) a polylactic acid resin mainly It is a distributed phase. At this time, the polymer phase different from (A) polylactic acid resin solution phase and (B) polylactic acid resin is different from (A) polylactic acid resin and (B) polymer type and usage amount different from polylactic acid resin. It seems to have a corresponding volume ratio.

The concentration of (A) polylactic acid resin and (B) polymer different from polylactic acid resin with respect to the organic solvent can be dissolved in the organic solvent as the concentration at which phase-separated state is obtained and industrially feasible. It is premised that it is within the range as long as possible, but preferably more than 1% by mass to 50% by mass, more preferably more than 1% by mass to 30% by mass, and still more preferably 2%, respectively, based on the total mass. It is mass%-20 mass%.

In the present invention, (A) the interfacial tension between the two phases of the polylactic acid resin solution phase and the polymer B solution phase is an organic solvent, so the interfacial tension is small, and the resulting emulsion is stable due to its nature. The particle size distribution seems to be smaller because it can be maintained.

The interfacial tension between the two phases in the present invention cannot be directly measured by the hanging drop method in which a different kind of solution is added to a commonly used solution because the interfacial tension is too small. By estimating from the surface tension, 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 can be estimated by the absolute value of r _1/2 = r ₁ −r ₂ .

In this case, 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. The lower limit is more than 0 mN / m.

  The viscosity between the two phases in the present invention affects the number average particle size and the particle size distribution, and the smaller the viscosity ratio, the smaller the particle size distribution.

  As a preferable range of the viscosity ratio between the two phases in the present invention, the lower limit is preferably 0.1, more preferably 0.2, still more preferably 0.3, particularly preferably 0.5, Remarkably preferred is 0.8.

Further, the upper limit is preferably 10, more preferably 5, still more preferably 3, particularly preferably 1.5, and particularly preferably 1.2. However, the viscosity ratio between the two phases here is defined as (A) polylactic acid resin solution phase / (B) polymer solution phase different from polylactic acid resin under the temperature condition for carrying out the present invention. And

  Using the phase-separated system thus obtained, the phase-separated liquid phases are mixed and emulsified, and then the emulsion is brought into contact with a poor solvent for (A) the aliphatic polyester resin to produce polymer fine particles. .

  In order to make fine particles, emulsion formation and fine particle precipitation steps can be carried out in a normal reaction vessel.

In the present invention, from the viewpoint of industrial feasibility, the temperature at which the emulsion formation and fine particle precipitation steps are carried out is 0 ° C. or higher, and a polymer different from (A) polylactic acid resin and (B) polylactic acid resin is dissolved. And the lower limit thereof is usually 0 ° C., preferably 10 ° C., more preferably 20 ° C., still more preferably 30 ° C., particularly preferably 40 ° C. Remarkably preferred is 50 ° C, most preferred is 60 ° C. The upper limit is preferably 300 ° C., more preferably 200 ° C., further preferably 160 ° C., particularly preferably 140 ° C., particularly preferably 120 ° C., and most preferably 100 ° C. It is.

  The pressure suitable for carrying out the present invention is in the range of normal pressure to 10 atm from the viewpoint of industrial feasibility. A preferred lower limit is 1 atmosphere. A preferable upper limit of the pressure is 5 atm, more preferably 3 atm, and further preferably 2 atm.

  Moreover, it is preferable to use an inert gas for the reaction tank. Specifically, nitrogen, helium, argon and carbon dioxide are preferable, and nitrogen and argon are more preferable.

  Under such conditions, the phase separation state is mixed to form an emulsion. That is, an emulsion is formed by applying a shearing force to the phase separation solution obtained above.

In forming the emulsion, the emulsion is formed so that the polylactic acid resin solution phase becomes particulate droplets. Generally, when the phase is separated, the volume of the polymer B solution phase is larger than the volume of the polylactic acid resin solution phase. In some cases, such an emulsion tends to be easily formed. In particular, the volume ratio of the polylactic acid resin solution phase is preferably 0.4 or less with respect to the total volume 1 of both phases, and is more preferably in the range of 0.4 to 0.1.

  When preparing the above phase diagram, it is possible to set an appropriate range by simultaneously measuring the volume ratio of each component in the concentration.

  The fine particles obtained by the production method of 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.

  For this reason, in order to obtain a sufficient shearing force to form an emulsion, it is sufficient to use stirring by a conventionally known method, such as a liquid phase stirring method using a stirring blade, a stirring method using a continuous biaxial mixer, or a homogenizer. It can mix by a well-known method, such as a mixing method and ultrasonic irradiation.

  In particular, in the case of stirring with a stirring blade, although depending on the shape of the stirring blade, the stirring speed is preferably 50 rpm to 1,200 rpm, more preferably 100 rpm to 1,000 rpm, and further preferably 200 rpm to 800 rpm. Yes, particularly preferably 300 to 600 rpm.

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

  Moreover, in order to generate an emulsion, not only a stirrer but the apparatus generally known widely, such as an emulsifier and a disperser, can always be used. Specifically, a batch type emulsifier such as a homogenizer (manufactured by IKA), “Polytron” (registered trademark) (manufactured by Kinematica), TK auto homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), Ebara Milder (Manufactured by Sakakibara Seisakusho), TK Philmix, 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 Kako Co., Ltd.) , Ultrasonic homogenizer, static mixer and the like.

  The emulsion thus obtained is subsequently subjected to a step of precipitating fine particles.

(A) In order to obtain the fine particles of polylactic acid resin, (A) the poor solvent for polylactic acid resin is brought into contact with the emulsion produced in the above step, and the fine particles are deposited in a size corresponding to the emulsion diameter. Let

  The contact method of the poor solvent and the emulsion may be a method of putting the emulsion in the poor solvent or a method of putting the poor solvent in the emulsion, but a method of putting the poor solvent in the emulsion is preferably used.

  In this case, the method for introducing the poor solvent is not particularly limited as long as the polymer fine particles produced in the present invention can be obtained, and either the continuous addition method or the batch addition method may be used. It is preferable to use a continuous addition method in order to prevent the particles from being attached and coalesced to have a large particle size distribution and to easily generate a lump exceeding 1000 μm.

  The continuous addition method in the present invention refers to a method in which the poor solvent to be added is added a plurality of times or continuously within a predetermined time. The batch addition method refers to a method in which a poor solvent is added at once in a short time. The short time here is less than 1 minute.

  The time for adding the poor solvent is 1 minute or more, preferably 5 minutes or more, more preferably 10 minutes or more, still more preferably 20 minutes or more, particularly preferably 30 minutes or more, and extremely preferably. Is one hour or more. The upper limit is not particularly limited, but is within 50 hours, preferably within 20 hours, more preferably within 10 hours, and particularly preferably within 5 hours.

  If it is carried out in a time shorter than this range, the particle size distribution may increase or a lump may be generated with the aggregation, fusion, and coalescence of the emulsion. Moreover, when it implements in the time longer than this, when industrial implementation is considered, it is unrealistic.

  By carrying out within this time range, when converting from emulsion to polymer fine particles, aggregation between particles can be suppressed, and polymer fine particles having a small particle size distribution can be obtained.

  Although the amount of the poor solvent to be added depends on the state of the emulsion, it may be an amount sufficient to precipitate fine particles, and the lower limit is 0.1 parts by mass or more with respect to 1 part by mass of the total mass of the emulsion. The amount is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and particularly preferably 0.5 parts by mass or more. The upper limit is not particularly limited, but is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 3 parts by mass or less, particularly preferably 2 parts by mass or less, and extremely preferably. Is 1 part by mass or less.

  The contact time between the poor solvent and the emulsion may be sufficient time for the fine particles to precipitate, but in order to cause sufficient precipitation and to obtain efficient productivity, preferably the addition of the poor solvent is completed. After 1 minute or more, more preferably 5 minutes or more, still more preferably 10 minutes or more, particularly preferably 20 minutes or more, and particularly preferably 30 minutes or more. The upper limit is not particularly limited, but is preferably 50 hours or less, more preferably 10 hours or less, further preferably 5 hours or less, particularly preferably 4 hours or less, and particularly preferably 3 hours or less. It is.

  The liquid in which the polymer fine particles thus prepared are dispersed is subjected to solid-liquid separation by a generally known method such as filtration, vacuum filtration, pressure filtration, centrifugal separation, centrifugal filtration, spray drying, etc. Can be obtained.

  The polymer fine particles separated by solid-liquid separation are washed with a solvent or the like as necessary to remove attached or contained impurities, etc., and are purified.

In the production method of the present invention, it is possible to recycle the organic solvent separated in the solid-liquid separation process performed when obtaining the fine particle powder and the polymer different from (B) polylactic acid resin again. is there.

The solvent obtained by solid-liquid separation is a mixture of a polymer, an organic solvent, and a poor solvent different from (B) polylactic acid resin. By removing the poor solvent from this solvent, it can be reused as a solvent for forming an emulsion.

  The method for removing the poor solvent is usually performed by a known method, and specific examples include simple distillation, vacuum distillation, precision distillation, thin-film distillation, extraction, and membrane separation. Distillation and precision distillation are preferably used.

When performing distillation operations such as simple distillation and vacuum distillation, the system is heated as in the case of polymer fine particle production, and (B) there is a possibility of promoting thermal decomposition of a polymer or organic solvent different from polylactic acid resin. For this reason, it is preferably performed in a state free from oxygen as much as possible, more preferably in an inert atmosphere. Specifically, it is particularly preferable to carry out under nitrogen, helium, argon and carbon dioxide conditions. In addition, a phenolic compound can be added again as an antioxidant.

When the used ketoester compound and the organic solvent are recycled, it is preferable to remove the poor solvent as much as possible. Specifically, the residual amount of the poor solvent is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total amount of the organic solvent to be recycled and the polymer different from (B) the polylactic acid resin. More preferably, it is 3 mass% or less, Most preferably, it is 1 mass% or less. When exceeding this range, the particle size distribution of the fine particles becomes large or the particles aggregate.

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

In the operation of removing the poor solvent, in reality, the polymer, the ketoester compound and the organic solvent other than the ketoester compound other than (B) polylactic acid resin may be lost. It is preferable to redo.

Thus, since the polylactic acid resin fine particles prepared by the method of the present invention can obtain particles having a small particle size distribution, the texture and feel of the polylactic acid resin fine particles are significantly higher than those of the polylactic acid resin fine particles obtained by the conventional method. Improved and has good fluidity when added with paint.

From these facts, the polylactic acid resin fine particles obtained in the present invention can be used extremely usefully and practically in various applications industrially.

  Specific examples of usages include the following.

  Specifically, facial cleansers, sunscreen agents, cleansing agents, lotions, emulsions, serums, creams, cold creams, after shaving lotions, shaving soaps, oil blotting papers, matifant agents and other skin care product additives, foundations Cosmetics such as, Ooiro, Water Oshii, Mascara, Face Powder, Virgin, Eyebrow, Mascara, Eyeline, Eye Shadow, Eye Shadow Base, Nose Shadow, Lipstick, Gloss, Hobe, Ogre, Manicure, Top Coat, etc. Additives for hair care products such as its modifier, shampoo, dry shampoo, conditioner, rinse, rinse-in shampoo, treatment, hair tonic, hair styling, hair oil, pomade, hair coloring agent. Perfume, eau de cologne, deodorant, baby powder, toothpaste, mouthwash, lip balm, soap and other amenity product additives, toner additives, paint and other rheology modifiers, medical diagnostic tests, automotive materials, construction Mechanical property improvers for molded products such as materials, mechanical property improvers such as films and fibers, raw materials for resin molded products such as rapid prototyping and rapid manufacturing, flash molding materials, paste resins for plastic sol, powder Blocking materials, powder fluidity improvers, lubricants, rubber compounding agents, abrasives, thickeners, filter agents and filter aids, gelling agents, flocculants, paint additives, oil absorbing agents, mold release agents , Plastic film / sheet slipperiness improver, antiblocking agent, gloss control agent, matte finish agent, light diffusing agent, high surface hardness Various modifiers such as upper agents and toughness improvers, spacers for liquid crystal display devices, chromatographic fillers, base materials and additives for cosmetic foundations, auxiliary agents for microcapsules, drug delivery systems and diagnostic agents Materials, perfume and pesticide retention agents, catalysts for chemical reactions and their supports, gas adsorbents, sintered materials for ceramic processing, standard particles for measurement and analysis, particles for the food industry, powder coating materials, Further, it can be used for toner for electrophotographic development.

In addition, the polylactic acid resin fine particles obtained by the production method of the present invention can use raw materials derived from non-lithiated raw materials and have properties as environmentally friendly materials. There is a possibility of substitution.

  Specific examples of the resin molded 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 case, switch, coil bobbin, condenser, variable capacitor case, optical pickup, oscillator, various terminal boards, transformer, plug, printed wiring board, tuner, speaker, microphone, headphones, small motor, magnetic head base, power module, housing Electrical / electronic parts such as semiconductor, liquid crystal, FDD carriage, FDD chassis, motor brush holder, parabolic antenna, computer-related parts; VTR parts, TV parts, irons, hair dryers, rice cooker parts Microwave oven parts, acoustic parts, audio equipment parts such as audio / laser discs / compact discs, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, word processor parts, home appliances such as office electrical appliance parts, office computers Machine-related parts such as parts, telephone-related parts, facsimile-related parts, copier-related parts, cleaning jigs, various bearings such as oilless bearings, stern bearings, underwater bearings, motor parts, lighters, typewriters, etc. , Optical instruments such as microscopes, binoculars, cameras, watches, precision machine parts; alternator terminals, alternator connectors, IC regulators, exhaust gas valves and other valves, fuel-related / exhaust / intake system pipes, air intakes nozzle Snorkel, intake manifold, fuel pump, engine coolant joint, carburetor main body, carburetor spacer, exhaust gas sensor, coolant sensor, oil temperature sensor, brake pad wear sensor, throttle position sensor, crankshaft position sensor, air flow meter, Thermostat base for air conditioner, heating hot air flow control valve, brush holder for radiator motor, water pump impeller, turbine vane, wiper motor related parts, dust distributor, starter switch, starter relay, transmission wire harness, window washer nozzle, air conditioner Panel switch board, coil for fuel-related solenoid valve, connector for fuse Horn terminals, electrical component insulation plates, step motor rotors, lamp sockets, lamp reflectors, lamp housings, brake pistons, solenoid bobbins, engine oil filters and ignition device cases. In addition, because of its excellent transparency and heat resistance, it is used as a component for optical recording / communications, such as imaging equipment, such as cameras, VTRs, projection TVs, viewfinders, filters, prisms, and Fresnel lenses. Various optical equipment (VD, CD, DVD, MD, LD, etc.) substrates, various disc substrate protective films, optical disc player pickup lenses, optical fibers, optical switches, optical connectors, and other information equipment related parts such as liquid crystal displays, flat panel displays, plasmas Display light guide plate, 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, pickup lens , Light guide films for touch panels, covers, etc., as parts related to transportation equipment such as automobiles, tail lamp lenses, head lamp lenses, inner lenses, amber caps, reflectors, extensions, side mirrors, room mirrors, side visors, instrument needles, instrument covers , Glazing typified by window glass, etc. as medical equipment related parts, spectacle lenses, spectacle frames, contact lenses, endoscopes, optical cells for analysis, etc., as building material related parts, lighting windows, road translucent plates, lighting covers It can also be applied to signboards, translucent sound insulation walls, and bathtub materials, and is extremely useful for these various applications.

Next, although the polylactic acid resin microparticles | fine-particles obtained with the manufacturing method of this invention and its manufacturing method are demonstrated in detail based on an Example, this invention is not limited to these.

(1) Number average particle size and particle size distribution measuring method:
The number-average particle diameter and particle diameter distribution index of the polylactic acid resin particles in the present invention, the polylactic acid resin particles dispersed in water, using a particle size analyzer manufactured by Nikkiso Co., Ltd. Microtrac MT3300EXII laser diffraction-scattering method It is measured. The particle size distribution index was a numerical value obtained by dividing the measured volume average particle size by the number average particle size. The measurement conditions are as follows.
-Equipment used: Nikkiso Co., Ltd., Microtrac MT3300EXII
Company analysis software DMS Ver. 11.0.0-246K
Measurement dispersion medium: ion-exchanged water (electric conductivity is 0.05 μS / cm)
Solvent refractive index: 1.333
・ Measurement time: 10 seconds
・ Number of measurements: 1 time
-Particle refractive index: 1.60
・ Transparency: Transmission
-Shape: non-spherical.

(2) Interfacial tension measurement method:
Using the automatic contact angle meter DM-501 of Kyowa Interface Science Co., Ltd. as an apparatus, on the hot plate, the relationship between the surface tension of each phase and air for each of the polymer A solution phase and the polymer B solution phase The results of the surface tension were r ₁ and r _2, and the interfacial tension was calculated from the absolute value of (r ₁ −r ₂ ), which is the difference between them.

(3) Differential scanning calorimetry:
Using a differential scanning calorimeter (DSC-7 model manufactured by Seiko Instruments Inc.), the measurement was performed at a temperature increase rate of 20 ° C./min in a nitrogen atmosphere.

(4) Weight average molecular weight:
(I) Molecular weight measurement of polylactic acid resin The weight average molecular weight was calculated using a gel permeation chromatography method and compared with a calibration curve with polymethyl methacrylate.
Apparatus: LC system manufactured by Waters Co., Ltd. Column: HFIP-806M x 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) Molecular weight measurement of polymer different from (B) polylactic acid resin The weight average molecular weight was calculated by comparing with a calibration curve with polyethylene glycol using gel permeation chromatography.
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.

(5) Measurement of linseed oil absorption:
In evaluating oil absorbency, which is an index of the porosity of the polylactic acid resin fine particles, Japanese Industrial Standard (JIS standard) JIS K5101 “Pigment Test Method Purified Sesame Oil Method” was used. About 100 mg of polylactic acid resin fine particles were precisely weighed on a watch glass, refined linseed oil (manufactured by Kanto Chemical Co., Inc.) was gradually added dropwise with a burette and kneaded with a palette knife. The dropping and kneading were repeated until a sample lump was formed, and the point at which the paste became a smooth hardness was taken as the end point. The amount of oil absorption (ml / 100 g) was calculated from the amount of refined linseed oil used for the dropwise addition.

(6) Evaluation of ketoester compound content in polylactic acid fine particles:
An absolute calibration curve method by gas chromatography was used for evaluating the ketoester compound content in the polylactic acid fine particles.
-Equipment: GC7890B manufactured by Agilent Technologies
Column: DB-WAX
・ Carrier gas: He
Detection: FID method.

(Example 1) <Method 1 for producing polylactic acid fine particles using ethyl acetoacetate solvent>
In a 200 ml four-necked flask, (A) 3.5 g of polylactic acid (D-form 1.2%, weight average molecular weight (PMMA conversion) 160,000, melting point 168 ° C.) as an aliphatic polyester resin, (C) organic As a constituent material of the solvent, 44.0 g of ketoester compound ethyl acetoacetate, and (B) 2.5 g of hydroxypropyl cellulose as a polymer different from the aliphatic polyester resin (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000) SP value 29.0 (J / cm ³ ) ^1/2 ) was added, heated to a temperature of 100 ° C., and stirred until the polymer was completely dissolved. Thereafter, the temperature of the system was lowered to 60 ° C. while stirring was continued. At this time, an emulsion was formed in the system. Subsequently, as a poor solvent, 50 g of a 1: 1 mixture of ion-exchanged water and ethanol was added dropwise over 2 hours. After the entire amount of the mixed solution had been added, the mixture was further stirred for 30 minutes, cooled to room temperature, and the resulting suspension was filtered, washed with 50 g of ion-exchanged water, and filtered. The obtained cake was vacuum-dried at a temperature of 80 ° C. for 10 hours to obtain 7.1 g of a powdery white solid.

When the obtained powder was analyzed by a particle size distribution analyzer, it was polylactic acid fine particles having a number average particle size of 9.4 μm and a particle size distribution index of 1.09. The oil absorption of linseed oil was 604 ml / 100 g and contained 0.6% by mass of ethyl acetoacetate. The SP value of the polylactic acid used in this example was determined by a calculation method and was 23.14 (J / cm ³ ) ^1/2 ). Further, when polylactic acid and hydroxypropylcellulose were separately dissolved in ethyl acetoacetate and observed by standing, it was found that two phases were separated, and the estimated value of the interfacial tension of this system was 2 mN / m or less. The solubility (at room temperature) of polylactic acid in a 1: 1 mixture of ion-exchanged water and ethanol, which is a poor solvent, was 0.1% by mass or less. Scanning electron micrographs of the obtained fine particles are shown in FIGS.

(Example 2) <Method 2 for producing polylactic acid fine particles using ethyl acetoacetate solvent>
In a 1000 ml four-necked flask, (A) 28.0 g of polylactic acid as an aliphatic polyester resin (D-form 1.2%, weight average molecular weight (PMMA conversion) 160,000, melting point 168 ° C.), (C) organic solvent As a polymer, 352.0 g of ethyl acetoacetate which is also a ketoester compound, and (B) 20.0 g of hydroxypropyl cellulose as a polymer different from the aliphatic polyester resin (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000) , SP value 29.0 (J / cm ³ ) ^1/2 ) was added, and the mixture was heated until the internal temperature reached 95 ° C. and stirred until the polymer was completely dissolved. Thereafter, the temperature of the system was lowered to 60 ° C. while stirring was continued. At this time, an emulsion was formed in the system. Subsequently, 400 g of a 1: 1 mixture of ion-exchanged water and ethanol was added dropwise as a poor solvent over 2 hours. After the entire amount of the mixed solution had been added, the mixture was further stirred for 30 minutes, cooled to room temperature, and the resulting suspension was filtered, washed with 350 g of ion-exchanged water, and filtered. The obtained cake was vacuum-dried at 50 ° C. for 10 hours to obtain 25.3 g of a powdery white solid. When the obtained powder was analyzed by a particle size distribution meter, it was polylactic acid fine particles having a number average particle size of 9.3 μm and a particle size distribution index of 1.09. The oil absorption of linseed oil was 513 ml / 100 g and contained 0.5% by mass of ethyl acetoacetate. The SP value of the polylactic acid used in this example was determined by a calculation method and was 23.14 (J / cm ³ ) ^1/2 ). Further, when polylactic acid and hydroxypropylcellulose were separately dissolved in ethyl acetoacetate and observed by standing, it was found that two phases were separated, and the estimated value of the interfacial tension of this system was 2 mN / m or less. The solubility (at room temperature) of polylactic acid in a 1: 1 mixture of ion-exchanged water and ethanol, which is a poor solvent, was 0.1% by mass or less. Scanning electron micrographs of the obtained fine particles are shown in FIGS.

(Example 3) <Method for producing polylactic acid fine particles using dimethyl malonate solvent>
In a 200 ml four-necked flask, (A) 2.5 g of polylactic acid as an aliphatic polyester resin (D isomer 1.2%, weight average molecular weight (PMMA conversion) 160,000, melting point 168 ° C.), (C) organic solvent 44.0 g of ethyl acetoacetate, which is also a ketoester compound, and 3.5 g of hydroxypropyl cellulose as a polymer different from (B) aliphatic polyester resin (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29. 0 (J / cm ³ ) ^1/2 ) was added, heated to a temperature of 100 ° C., and stirred until the polymer was completely dissolved. Thereafter, the temperature of the system was lowered to 60 ° C. while stirring was continued. At this time, an emulsion was formed in the system. Subsequently, 50 g of a 1: 1 mixture of ion-exchanged water and ethanol was added dropwise as a poor solvent over 2 hours. After the entire amount of the mixed solution had been added, the mixture was further stirred for 30 minutes, and the resulting suspension was filtered, washed with 50 g of ion-exchanged water, and filtered. The obtained cake was vacuum-dried at a temperature of 50 ° C. for 10 hours to obtain 2.3 g of a powdery white solid.

When the obtained powder was analyzed by a particle size distribution meter, it was polylactic acid fine particles having an average particle size of 19.3 μm and a particle size distribution index of 2.9. The oil absorption of linseed oil was 412 ml / 100 g and contained 0.3% by mass of ethyl acetoacetate. The SP value of the polylactic acid used in this example was determined by a calculation method and was 23.14 (J / cm ³ ) ^1/2 ). Further, when polylactic acid and hydroxypropylcellulose were separately dissolved in dimethyl malonate and allowed to stand, it was found that two phases were separated, and the estimated value of the interfacial tension of this system was 2 mN / m or less. The solubility (at room temperature) of polylactic acid in a 1: 1 mixture of ion-exchanged water and ethanol, which is a poor solvent, was 0.1% by mass or less. Scanning electron micrographs of the obtained fine particles are shown in FIGS.

Example 4 <Method 3 for producing polylactic acid microparticles using ethyl acetoacetate solvent>
In a 1000 ml four-necked flask, (A) 20.0 g of polylactic acid as an aliphatic polyester resin (D-form 1.2%, weight average molecular weight (PMMA conversion) 160,000, melting point 168 ° C.), (C) organic solvent As a polymer, 360.0 g of ethyl acetoacetate, which is also a ketoester compound, and 20.0 g of polyvinylpyrrolidone as a polymer different from (B) aliphatic polyester resin (manufactured by Nippon Shokubai Co., Ltd., weight average molecular weight 1,100,000) , SP value 25.6 (J / cm ³ ) ^1/2 ) was added, and the mixture was heated until the internal temperature reached 95 ° C. and stirred until the polymer was completely dissolved. Thereafter, the temperature of the system was lowered to 60 ° C. while stirring was continued. At this time, an emulsion was formed in the system. Subsequently, 400 g of a 1: 1 mixture of ion-exchanged water and ethanol was added dropwise as a poor solvent over 2 hours. After the addition of the entire amount of the mixed solution, the mixture was further stirred for 30 minutes, cooled to room temperature, and the resulting suspension was filtered, washed with 350 g of ethanol and filtered. The obtained cake was vacuum-dried at a temperature of 50 ° C. for 10 hours to obtain 26.5 g of a powdery white solid. When the obtained powder was analyzed by a particle size distribution meter, it was polylactic acid fine particles having a number average particle size of 9.7 μm and a particle size distribution index of 2.02. The oil absorption of linseed oil was 525 ml / 100 g and contained 0.6% by mass of ethyl acetoacetate. The SP value of polylactic acid used in this example was determined by a calculation method and was 23.14 (J / cm ³ ) ^1/2 ). Further, when polylactic acid and polyvinylpyrrolidone were separately dissolved in ethyl acetoacetate and observed by standing, it was found that two phases were separated, and the estimated value of the interfacial tension of this system was 2 mN / m or less. Moreover, the solubility (normal temperature) of the polylactic acid with respect to the 1: 1 mixed liquid of ion-exchange water and ethanol which is a poor solvent was 0.1 mass% or less. Scanning electron micrographs of the obtained fine particles are shown in FIGS.

(Example 5) <Method 4 for producing polylactic acid microparticles using ethyl acetoacetate solvent>
In a 200 ml four-necked flask, (A) 3.5 g of polylactic acid as an aliphatic polyester resin (D isomer 1.2%, weight average molecular weight (PMMA conversion) 160,000, melting point 168 ° C.), (C) organic solvent 44.0 g of ethyl acetoacetate, which is also a ketoester compound, and (B) 2.5 g of hydroxypropyl cellulose as a polymer different from the aliphatic polyester resin (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000) , SP value 29.0 (J / cm ³ ) ^1/2 ) was added, and the mixture was heated until the internal temperature reached 95 ° C. and stirred until the polymer was completely dissolved. Thereafter, the temperature of the system was lowered to 60 ° C. while stirring was continued. At this time, an emulsion was formed in the system. Subsequently, 25 g of ethanol was collectively added as a poor solvent. After the entire amount of ethanol was added, the mixture was further stirred for 10 minutes, and then 25 g of ion-exchanged water was added all at once. After the addition of the entire amount of ion-exchanged water, the mixture was further stirred for 10 minutes, cooled to room temperature, and the resulting suspension was filtered, washed with 50 g of ion-exchanged water, and filtered. The obtained cake was vacuum-dried at a temperature of 50 ° C. for 10 hours to obtain 3.1 g of a powdery white solid. When the obtained powder was analyzed with a particle size distribution meter, it was polylactic acid fine particles having a number average particle size of 6.7 μm and a particle size distribution index of 1.56. The oil absorption of linseed oil was 391 ml / 100 g and contained 0.3% by mass of ethyl acetoacetate. The SP value of polylactic acid used in this example was determined by a calculation method and was 23.14 (J / cm ³ ) ^1/2 ). In addition, when polylactic acid and hydroxypropylcellulose were separately dissolved in ethyl acetoacetate and allowed to stand and observed, it was found that they separated into two phases, and the estimated value of the interfacial tension of this system was 2 mN / m or less. The solubility (at room temperature) of polylactic acid in a 1: 1 mixture of ion-exchanged water and ethanol, which is a poor solvent, was 0.1% by mass or less. Scanning electron micrographs of the obtained fine particles are shown in FIG. 9 and FIG.

(Example 6) <Method 5 for producing polylactic acid microparticles using ethyl acetoacetate solvent>
In a 200 ml four-necked flask, (A) 3.5 g of polylactic acid as an aliphatic polyester resin (D isomer 1.2%, weight average molecular weight (PMMA conversion) 160,000, melting point 168 ° C.), (C) organic solvent 43.0 g of ethyl acetoacetate which is also a ketoester compound, and (B) 3.5 g of polyvinyl pyrrolidone as a polymer different from the aliphatic polyester resin (manufactured by Nippon Shokubai Co., Ltd., weight average molecular weight 1,100,000) , SP value 25.6 (J / cm ³ ) ^1/2 ) was added, and the mixture was heated until the internal temperature reached 95 ° C. and stirred until the polymer was completely dissolved. Thereafter, the temperature of the system was lowered to 40 ° C. while stirring was continued. At this time, an emulsion was formed in the system. Subsequently, 25 g of ethanol as a poor solvent was added all at once. After all the ethanol was added, the mixture was further stirred for 1 minute, and then 25 g of ethanol was added all at once. After the entire amount of ethanol was added, the mixture was further stirred for 10 minutes, cooled to room temperature, and the resulting suspension was filtered, washed with 50 g of ethanol and filtered. The obtained cake was vacuum-dried at a temperature of 50 ° C. for 10 hours to obtain 3.2 g of a powdery white solid. When the obtained powder was analyzed by a particle size distribution analyzer, it was polylactic acid fine particles having a number average particle size of 7.4 μm and a particle size distribution index of 1.92. The oil absorption of linseed oil was 422 ml / 100 g and contained 0.4% by mass of ethyl acetoacetate. The SP value of polylactic acid used in this example was determined by a calculation method and was 23.14 (J / cm ³ ) ^1/2 ). In addition, when polylactic acid and polyvinylpyrrolidone were separately dissolved in ethyl acetoacetate and left to stand, it was found that they separated into two phases, and the estimated value of the interfacial tension of this system was 2 mN / m or less. Moreover, the solubility (normal temperature) of the polylactic acid with respect to ethanol which is a poor solvent was 0.1 mass% or less. Scanning electron micrographs of the obtained fine particles are shown in FIGS.

(Example 7) <Method 6 for producing polylactic acid microparticles using ethyl acetoacetate solvent>
In a 200 ml four-necked flask, (A) 3.5 g of polylactic acid as an aliphatic polyester resin (D isomer 1.2%, weight average molecular weight (PMMA conversion) 160,000, melting point 168 ° C.), (C) organic solvent As a constituent material, 44.0 g of ethyl acetoacetate which is a ketoester compound, and 2.5 g of hydroxypropyl cellulose as a polymer different from (B) aliphatic polyester resin (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) was added, and the mixture was heated to a temperature of 100 ° C. and stirred until the polymer was completely dissolved. Thereafter, the temperature of the system was lowered to 60 ° C. while stirring was continued. At this time, an emulsion was formed in the system. Subsequently, 25 g of ion-exchanged water heated to a temperature of 60 ° C. as a poor solvent was added all at once. After the addition of the entire amount of ion-exchanged water, the mixture was further stirred for 10 minutes, and 25 g of ethanol warmed to a temperature of 60 ° C. was added all at once. After the entire amount of ethanol was added, the mixture was further stirred for 30 minutes, cooled to room temperature, and the resulting suspension was filtered, washed with 50 g of ethanol, and filtered. The obtained cake was vacuum-dried at a temperature of 50 ° C. for 10 hours to obtain 2.9 g of a powdery white solid.

When the obtained powder was analyzed by a particle size distribution meter, it was polylactic acid fine particles having a number average particle size of 13.92 μm and a particle size distribution index of 2.60. The oil absorption of linseed oil was 725 ml / 100 g and contained 0.4% by mass of ethyl acetoacetate. The SP value of polylactic acid used in this example was determined by a calculation method and was 23.14 (J / cm ³ ) ^1/2 ). In addition, when polylactic acid and hydroxypropylcellulose were separately dissolved in ethyl acetoacetate and observed standing, it was found that two phases were separated, and the estimated value of the interfacial tension of this system was 2 mN / m or less. Moreover, the solubility (normal temperature) of the polylactic acid with respect to the 1: 1 mixed liquid of ion-exchange water and ethanol which is a poor solvent was 0.1 mass% or less. Scanning electron micrographs of the obtained fine particles are shown in FIGS.

(Example 8) <Production method 7 of polylactic acid fine particles using ethyl acetoacetate solvent>
In a 10 L autoclave, (A) 280 g of polylactic acid (D-form 1.2%, weight average molecular weight Mw (converted to PMMA) 160,000, melting point 168 ° C.) as an aliphatic polyester resin, and (C) an organic solvent As a polymer, 3520 g of ethyl acetoacetate, which is also a ketoester compound, and 200 g of hydroxypropylcellulose as a polymer different from (B) aliphatic polyester resin (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 ( J / cm ³ ) ^1/2 ) was added, and the mixture was heated until the internal temperature reached 95 ° C., and stirred until the polymer was completely dissolved. Thereafter, the temperature of the system was lowered to 60 ° C. while stirring was continued. At this time, an emulsion was formed in the system. Subsequently, 4000 g of a 1: 1 mixture of ion-exchanged water and ethanol was added dropwise as a poor solvent over 2 hours. After the addition of the entire amount of water mixture, the temperature was lowered to room temperature, and the resulting suspension was filtered, washed with 5600 g of ethanol, washed with 16800 g of ion-exchanged water, and filtered. The obtained cake was vacuum-dried at a temperature of 50 ° C. for 10 hours to obtain 250 g of a powdery white solid. When the obtained powder was analyzed by a particle size distribution analyzer, it was polylactic acid fine particles having a number average particle size of 7.6 μm and a particle size distribution index of 1.30. The oil absorption of linseed oil was 510 ml / 100 g and contained 0.5% by mass of ethyl acetoacetate. The SP value of polylactic acid used in this example was determined by a calculation method and was 23.14 (J / cm ³ ) ^1/2 ). In addition, when polylactic acid and hydroxypropylcellulose were separately dissolved in ethyl acetoacetate and observed standing, it was found that two phases were separated, and the estimated value of the interfacial tension of this system was 2 mN / m or less. Moreover, the solubility (normal temperature) of the polylactic acid with respect to the 1: 1 mixed-solution water of ion-exchange water and ethanol which is a poor solvent was 0.1 mass% or less. Scanning electron micrographs of the obtained fine particles are shown in FIGS.

(Comparative Example 1) <Method 8 for producing polylactic acid fine particles using ethyl acetoacetate solvent>
In a 200 ml four-necked flask, (A) 3.5 g of polylactic acid as an aliphatic polyester resin (D isomer 1.2%, weight average molecular weight (PMMA conversion) 160,000, melting point 168 ° C.), (C) organic solvent As a constituent material, 44.0 g of ethyl acetoacetate which is a ketoester compound, and 2.5 g of hydroxypropyl cellulose as a polymer different from (B) aliphatic polyester resin (manufactured by Tokyo Chemical Industry Co., Ltd., weight average molecular weight 118,000, SP value 29.0 (J / cm ³ ) ^1/2 ) was added, and the mixture was heated to a temperature of 100 ° C. and stirred until the polymer was completely dissolved. Thereafter, the temperature of the system was lowered to 60 ° C. while stirring was continued. At this time, an emulsion was formed in the system. Subsequently, as a poor solvent, ion exchange water of 50 g of a 1: 1 mixture of ion exchange water and ethanol was added all at once within 5 seconds. After the addition of the entire amount of the mixed solution, the mixture was further stirred for 10 minutes. As a result, polylactic acid became a lump of 1000 μm or more in the system and could not be formed into fine particles.

Claims (2)

  (A) At least one selected from polyvinyl pyrrolidone, hydroxypropyl cellulose, polyvinyl alcohol, polyethylene oxide and polyethylene glycol as a polymer different from (B) polylactic acid resin and (C) ketoester In a system in which an organic solvent containing a compound is dissolved and mixed and phase-separated into two phases: a solution phase mainly composed of polylactic acid resin and a solution phase mainly composed of a polymer different from polylactic acid resin. A method for producing polylactic acid resin fine particles comprising a step of depositing polylactic acid resin fine particles by contacting at least one selected from ethanol, methanol and water as a poor solvent for polylactic acid resin after formation . METHOD The method for producing a polylactic acid resin particles of claim 1, wherein in which applies shear force to form an emulsion.