WO2011142283A1

WO2011142283A1 - Method for producing polylactic acid microparticles, polylactic acid microparticles, and crystal nucleation agent, molded article, and surface modifier using the same

Info

Publication number: WO2011142283A1
Application number: PCT/JP2011/060469
Authority: WO
Inventors: 宏樹上原; 健山延
Original assignee: 国立大学法人群馬大学
Priority date: 2010-05-10
Filing date: 2011-04-28
Publication date: 2011-11-17
Also published as: JPWO2011142283A1; JP5652831B2

Abstract

Provided is a method for producing polylactic acid microparticles, which comprises: a preliminary step in which a polymer compound solution, which is obtained by dissolving in a first solvent a polymer compound containing structural units derived from l-lactic acid and structural units derived from d-lactic acid, is retained in a first liquid retaining part while a second solvent, which is a poor solvent of the polymer compound, is retained in a second liquid retaining part of a permeation device having two liquid retaining parts separated by a permeation membrane having pores with a diameter of 0.5 nm to 1,000 nm; and a permeation step in which the polymer compound solution retained in the first liquid retaining part is brought into contact with the second solvent by causing the polymer compound solution to permeate through the permeation membrane at a flow rate of 1×10^-3 mL/(min·cm²) to 10,000 mL/(min·cm²).

Description

Method for producing polylactic acid fine particles, polylactic acid fine particles, and crystal nucleating agent, molded article, and surface modifier using the same

The present invention relates to a method for producing polylactic acid fine particles, polylactic acid fine particles, and a crystal nucleating agent, a molded product, and a surface modifier using the same.

In recent years, biomass resins using plant components as raw materials have attracted attention, and various studies have been conducted on conventional synthetic resins synthesized from petroleum. Even if such a plant-derived resin is incinerated at the time of disposal, the plant again photosynthesizes the carbon dioxide generated and is carbon neutral in that it becomes a raw material, and replacing this with a conventional synthetic resin is a global warming It is a material that is expected to lead to prevention. As such biological resin, for example, polyhydroxybutyrate and polylactic acid are known. Of these, polylactic acid is attracting attention because it has advantages such as the ability to use lactic acid or lactide obtained from plant raw materials such as corn as a raw material and the fact that it is thermoplastic and can be melt-molded.

However, the α crystal obtained from plant-derived poly-L-lactic acid (hereinafter sometimes referred to as “PLLA”) has a melting point as low as 170 ° C., so that it can be applied as a resin molding or synthetic fiber. There is a need for improved heat resistance. Further, the α crystal is a problem when used as a member because of its high hydrolyzability.

On the other hand, as polylactic acid, there are the above-mentioned PLLA consisting only of L-lactic acid units which are optical isomers, and poly-D-lactic acid consisting only of D-lactic acid units (hereinafter sometimes referred to as “PDLA”). . A stereocomplex crystal in which PLLA and PDLA are alternately packed at 1: 1 (hereinafter sometimes referred to as “Sc crystal”) has a remarkably high melting point of 230 ° C. and has hydrolysis resistance. It has the potential as an engineering plastic. It is known that the Sc crystal is formed, for example, by mixing PLLA and PDLA in a solution or in a molten state (see Patent Document 1, Non-Patent Documents 1 and 2). Attempts have also been made to use the Sc crystal as a crystal nucleating agent that promotes crystallization of poly-L-lactic acid (see, for example, Patent Document 2).

JP 63-241024 JP 2005-290257 A

As described above, when using polylactic acid stereocomplex crystal particles as a crystal nucleating agent, in order to form crystals that are uniformly crystallized, tough, and highly transparent, the particle size is small, and It is desirable to use polylactic acid particles having a high stereocomplex crystal ratio as a crystal nucleating agent. However, for example, in a method of obtaining a stereocomplex crystal by dropping a solution in which poly-L-lactic acid and poly-D-lactic acid are dissolved in equal amounts into a poor solvent for polylactic acid (described later), In addition to having a particle size of 1 μm or more, it is difficult to directly obtain particles having a high ratio of the stereocomplex crystals. As described above, it is difficult to obtain polylactic acid fine particles having a small particle diameter and a high ratio of the stereocomplex crystal by the conventional method.

The present invention requires a method for producing polylactic acid microparticles, which can produce polylactic acid microparticles having a small particle size and containing a large amount of poly-L-lactic acid and poly-D-lactic acid stereocomplex crystals. In addition, polylactic acid fine particles that can be obtained by using polylactic acid fine particles containing a stereocomplex crystal of poly-L-lactic acid and poly-D-lactic acid as a raw material, and polylactic acid fine particles having high transparency and strength, and crystals using the same There is a need to provide nucleating agents, compacts, and surface modifiers.

The above problem is solved by the following means. That is,
The invention according to claim 1
In a permeation device having two liquid containing portions partitioned by a permeable membrane having pores having a diameter of 0.5 nm or more and 1000 nm or less, a structural unit derived from L-lactic acid and D-lactic acid are provided in one liquid containing portion. A polymer compound solution obtained by dissolving a polymer compound containing a derived structural unit in a first solvent is accommodated, and a second solvent that is a poor solvent for the polymer compound is accommodated in the other liquid container. A preparation process;
The polymer solution accommodated in the liquid accommodating portion of the ^{one, 1 × 10 -3 mL / (} min · cm 2) or more 10000mL / (min · cm ²⁾ be transmitted through said permeable membrane at a flow rate not less than And a permeation step for bringing the polymer compound solution into contact with the second solvent.
It is.

The invention according to claim 2
2. The polylactic acid fine particles according to claim 1, further comprising a permeation membrane wetting step of bringing the permeation membrane into contact with a liquid in advance and substituting the gas in the pores of the permeation membrane with the liquid prior to the preparation step. It is a manufacturing method.
The invention according to claim 3
3. The method for producing polylactic acid microparticles according to claim 1, wherein the polymer compound is a mixture of a poly-L-lactic acid homopolymer and a poly-D-lactic acid homopolymer.

The invention according to claim 4
Including a stereocomplex crystal component of poly-L-lactic acid and poly-D-lactic acid, wherein the ratio of the stereocomplex crystal component to the total crystal component of polylactic acid is 50% or more and 100% or less, and the number average Polylactic acid fine particles having a particle size of 0.5 nm or more and less than 1000 nm.

The invention according to claim 5
The polylactic acid fine particles according to claim 4, wherein the ratio of the total crystal component to the total of the amorphous component of polylactic acid and the total crystal component is 10% or more.

The invention according to claim 6
A crystal nucleating agent comprising the polylactic acid fine particles according to claim 4 or 5.

The invention according to claim 7 provides:
A molded article comprising the polylactic acid fine particles according to claim 4 or 5.

The invention according to claim 8 provides:
A surface modifier comprising the polylactic acid fine particles according to claim 4 or 5.

According to the present invention, there is provided a method for producing polylactic acid fine particles, which can produce fine particles of polylactic acid having a small particle size and containing a large amount of poly-L-lactic acid and poly-D-lactic acid stereocomplex crystals. Furthermore, according to the present invention, the polylactic acid fine particles can be obtained by using polylactic acid fine particles containing a stereocomplex crystal of poly-L-lactic acid and poly-D-lactic acid as a raw material. And a crystal nucleating agent, a molded body, and a surface modifier using the same.

FIG. 1 is a schematic view schematically showing an example of an apparatus used in a method for producing polylactic acid fine particles. FIG. 2 is a conceptual diagram showing an example of a method for producing a film made of polylactic acid fine particles. FIG. 3 is an SEM image of the polylactic acid microparticles obtained in Example 1. FIG. 4 a is an SEM image of the polylactic acid microparticles obtained in Example 2. FIG. 4 b is an SEM image of the polylactic acid microparticles obtained in Example 2. FIG. 4 c is an SEM image of the polylactic acid microparticles obtained in Example 2. FIG. 4d is a bar graph showing the particle size distribution of the polylactic acid microparticles obtained in Example 2. FIG. 5 a is an SEM image of the polylactic acid microparticles obtained in Example 3. FIG. 5 b is an SEM image of the polylactic acid microparticles obtained in Example 3. FIG. 5 c is a bar graph showing the particle size distribution of the polylactic acid fine particles obtained in Example 3. 6a is an SEM image of the polylactic acid fine particles obtained in Comparative Example 1. FIG. FIG. 6 b is an SEM image of the polylactic acid microparticles obtained in Comparative Example 1. FIG. 6 c is an SEM image of the polylactic acid microparticles obtained in Comparative Example 1. FIG. 7 a is an SEM image of the polylactic acid microparticles obtained in Example 4. FIG. 7 b is an SEM image of the polylactic acid microparticles obtained in Example 4. FIG. 7 c is a bar graph showing the particle size distribution of the polylactic acid fine particles obtained in Example 4. FIG. 8 a is an SEM image of the polylactic acid microparticles obtained in Example 5. FIG. 8 b is an SEM image of the polylactic acid microparticles obtained in Example 5. FIG. 8 c is an SEM image of the polylactic acid microparticles obtained in Example 5. FIG. 8d is a bar graph showing the particle size distribution of the polylactic acid fine particles obtained in Example 5. FIG. 9 is an SEM image of the polylactic acid microparticles obtained in Example 6. FIG. 10 is an SEM image of the polylactic acid fine particles obtained in Example 7. FIG. 11 is an SEM image of the polylactic acid fine particles obtained in Example 8. FIG. 12 is an SEM image of the polylactic acid microparticles obtained in Example 9. FIG. 13 is a DSC melting curve of the film 1 obtained in Example 2 and the polylactic acid fine particles obtained in Example 5. FIG. 14 is a WAXD curve of the surface coat layer obtained in Example 10.

Hereinafter, the present invention will be described in detail.
[Production method of polylactic acid fine particles]
In the method for producing polylactic acid fine particles in the present invention, one liquid container of the permeation device having two liquid containers separated by a permeable membrane having pores having a diameter of 0.5 nm or more and 1000 nm or less is added to L- A polymer compound comprising a structural unit derived from lactic acid (hereinafter sometimes referred to as “L-lactic acid unit”) and a structural unit derived from D-lactic acid (hereinafter sometimes referred to as “D-lactic acid unit”) A preparatory step of containing a second solvent, which is a poor solvent for the polymer compound, in the other liquid container, and the one liquid container the polymer solution which is housed in ^{part, 1 × 10 -3 mL / (} min · cm 2) or more 10000mL / (min · cm ²⁾ by transmitting said permeable membrane at a flow rate not less than, the polymer Compound solution It includes a transmission step of contacting the serial second solvent, and may have other steps as necessary.

When the production method of the present invention is used, the particle size is small, and poly-L-lactic acid (hereinafter sometimes referred to as “PLLA”) and poly-D-lactic acid (hereinafter referred to as “PDLA”). In other words, polylactic acid fine particles containing a large amount of stereocomplex crystals (hereinafter sometimes referred to as “Sc crystals”) are formed. In general, fine particles having a small particle diameter have a larger specific surface area per unit volume (or unit mass) than particles having a large particle diameter, and the ratio of the crystal component tends to be small. However, by using the production method of the present invention, it is possible to produce polylactic acid fine particles having a high ratio of crystal components (that is, a ratio of crystal components with respect to the total of the amorphous component and the crystal components) despite the small particle size. The reason is not clear, but is presumed as follows.

In the permeation step, the polymer compound in the polymer compound solution partitioned in the pores of the permeable membrane, that is, in the space having the diameter in the above range, passes through the permeable membrane at a permeation rate in the above range. Crystallized upon contact with a poor solvent. For this reason, it is considered that molecules of the polymer compound are confined in a narrow pore space, and the L-lactic acid unit and the D-lactic acid unit contained in the polymer compound are likely to come into contact with each other. Then, it is presumed that when the crystallization starts in a state where the L-lactic acid unit and the D-lactic acid unit are in contact in the narrow space, an Sc crystal of PLLA and PDLA is easily formed. In addition, since the crystallization is started in a state where the molecules of the polymer compound are confined in the narrow space as described above, a small particle diameter reflecting the diameter of the pores is obtained. Presumably, polylactic acid fine particles are formed. For the reasons described above, it is considered that fine particles of polylactic acid having a small particle diameter and containing a large amount of Sc crystals are formed by using the production method of the present invention. Then, by efficiently forming Sc crystals as described above, polylactic acid fine particles having a high ratio of crystal components are formed.

In particular, in the permeation step, when the second solvent is in contact with the surface of the permeable membrane on the side of the other liquid container, the polymer compound solution permeates while contacting the second solvent. When the polymer compound is crystallized in a state of being partitioned into the space, polylactic acid fine particles having a small particle size that contains a large amount of Sc crystals and reflects the diameter of the pores are more easily formed. Conceivable.
The manufacturing method of the present invention preferably further includes a step of bringing the permeable membrane into contact with a liquid in advance and replacing the gas in the pores of the permeable membrane with the liquid prior to the preparation step. By replacing the gas in the pores of the permeable membrane with a liquid in advance, the polymer compound solution and the second solution come into contact from the beginning of the permeation step, so that polylactic acid fine particles can be obtained efficiently.

Examples of the polymer compound containing an L-lactic acid unit and a D-lactic acid unit include a polymer compound containing a polylactic acid molecule containing an L-lactic acid unit and a D-lactic acid unit in one molecule, Examples include a polylactic acid molecule containing an L-lactic acid unit and no D-lactic acid unit, and a polylactic acid molecule containing a D-lactic acid unit and no L-lactic acid unit in one molecule.

Examples of the polymer compound containing an L-lactic acid unit and a D-lactic acid unit in one molecule include, for example, a copolymer of PLLA and PDLA, or a copolymer of PLLA, PDLA, and a polymer compound other than polylactic acid. Examples include coalescence.
Examples of the polymer compound containing an L-lactic acid unit in one molecule and not containing a D-lactic acid unit include, for example, a homopolymer of PLLA and a copolymer of PLLA and a polymer compound other than polylactic acid (hereinafter referred to as “PLA”). Similarly, a polymer compound that contains a D-lactic acid unit in one molecule and does not contain an L-lactic acid unit includes, for example, a single weight of PDLA. And a copolymer of PDLA and a polymer compound other than polylactic acid (hereinafter sometimes referred to as “PDLA copolymer”).

Among the above, the polymer compound containing an L-lactic acid unit and a D-lactic acid unit is preferably a mixture of a PLLA homopolymer and a PDLA homopolymer.
By using a mixture of a homopolymer of PLLA and a homopolymer of PDLA to produce polylactic acid fine particles by the production method of the present invention, for example, the ratio of Sc crystals in all crystal components is 100%. It is also possible to produce polylactic acid microparticles that do not contain α crystals. And as above-mentioned, if the manufacturing method of this invention is used, although the particle size is small, the polylactic acid microparticles | fine-particles with a high ratio of a crystal component can be manufactured.

Hereafter, each process of the manufacturing method of the polylactic acid microparticles | fine-particles in this invention is demonstrated in detail.
<Preparation process>
In the preparation step, an L-lactic acid unit and D-lactic acid are added to one liquid container of the permeation device having two liquid containers separated by a permeable membrane having pores having a diameter of 0.5 nm to 1000 nm. A polymer compound solution obtained by dissolving a polymer compound containing a unit in a first solvent is accommodated, and a second solvent that is a poor solvent for the polymer compound is accommodated in the other liquid accommodating portion.

-Polymer compound containing L-lactic acid unit and D-lactic acid unit-
The polymer compound containing an L-lactic acid unit and a D-lactic acid unit is not particularly limited as long as the polymer compound contains an L-lactic acid unit and a D-lactic acid unit. There may be a form containing both L-lactic acid units and D-lactic acid units, or a mixture of molecules containing only L-lactic acid units and molecules containing only D-lactic acid units.
That is, the polymer compound may be polylactic acid obtained by copolymerization of both L-lactic acid and D-lactic acid monomer units, or may be either PLLA or PDLA, or may be PLLA or PDLA as described above. It may be a mixture.

The PLLA is a polymer mainly composed of L-lactic acid units, and is preferably a polymer composed of 100% L-lactic acid units excluding inevitable impurities (that is, a homopolymer of PLLA).
The PDLA is a polymer having a D-lactic acid unit as a main component, like the PLLA, and is preferably a polymer composed of 100% D-lactic acid units excluding inevitable impurities (that is, a PDLA homopolymer). It is.
The ends of PLLA and PDLA may be sealed with a terminal blocking group. Examples of such end capping groups include acetyl groups, ester groups, ether groups, amide groups, urethane groups, hydroxyl groups, and the like.

PLLA and PDLA can be produced by a known polylactic acid polymerization method. Examples of the production method include lactide ring-opening polymerization, lactic acid dehydration condensation, or a combination of these with solid-phase polymerization. And a method of melting and solidifying. As a more specific production method, Makromol. Chem. Volume 191, P481-488 (1990) or as described in JP-A-1-225622, a living step polymerization method of lactide, which is a cyclic dimer of lactic acid, as described in JP-A-2003-64174. And a direct ring-opening polymerization method of racemic lactide using a specific stereoselective polymerization catalyst, a melt polymerization method from lactic acid, a ring-opening polymerization method of lactide, and the like.

Moreover, PLLA and PDLA may contain a catalyst involved in polymerization as long as thermal stability is not impaired. Examples of the catalyst include various aluminum compounds, lithium compounds, tin compounds, titanium compounds, calcium compounds, organic acids, inorganic acids and the like, and a stabilizer for inactivating these may be present together. .

When a mixture of PLLA and PDLA is used as the polymer compound, the mixing ratio of PLLA and PDLA is appropriately selected in a mass ratio ranging from 1:99 to 99: 1. From the viewpoint of Sc crystal production efficiency Is preferably in the range of 10:90 to 90:10, and more preferably prepared so that both are equivalent (50 ± 5: 50 ± 5).
The above-mentioned mixture of PLLA and PDLA may contain other polymer compounds in addition to PLLA and PDLA, but it is preferable not to contain other polymer compounds except for inevitable impurities.

As described above, a polylactic acid copolymer may be used as the polymer compound. The copolymer of polylactic acid is not particularly limited as long as it contains at least one of an L-lactic acid unit and a D-lactic acid unit. Specifically, for example, a copolymer of PLLA and PDLA, a PLLA copolymer, and the like. Examples thereof include a polymer and a PDLA copolymer.
Moreover, as a polymer compound, a copolymer of PLLA and PDLA, a mixture of PLLA copolymer and PDLA homopolymer, a mixture of PLLA homopolymer and PDLA copolymer, or a PLLA homopolymer and a PDLA homopolymer. A form using a mixture with a coalescence is preferable from the viewpoint of producing polylactic acid fine particles having many Sc crystals. Among these, a form using a block copolymer as a copolymer or a form using a mixture of a PLLA homopolymer and a PDLA homopolymer is more preferable, and a mixture of a PLLA homopolymer and a PDLA homopolymer is used. A form is further preferred.

Examples of the “polymer compound other than polylactic acid” contained in the PLLA copolymer or PDLA copolymer include those that can be dissolved in a solvent common to polylactic acid. Specifically, for example, polystyrene, polystyrene sulfonic acid, polymethyl methacrylate, polyethylene glycol, polyethylene oxide, polypropylene glycol, polypropylene oxide, poly ε-caprolactone, polybutadiene, polydimethylsiloxane, polyethylene, polynorbornenyl ethyl styrene, poly Norbornenyl ethyl styrene-s-styrene, polynorbornene, polyhexamethyl carbonate, polyhexyl norbornene, poly-n-propyl-p-styrene sulfonic acid, polybutyl succinate, polydicyclopentadiene, polydimethylacrylamide, polycyclohexylethylene , Poly-1,5-dioxepan-2-one, polymentide, polyacrylamide, poly-4-vinylpyridine, polydimethyla Rilamide, poly-N-isopropylacrylamide, polyisoprene, poly-3-alkylthiophene, polydioxanone, poly-N, N-dimethylamino-2-ethylmetallate, poly-3-hydroxybutyrate, poly-2-hydroxymethacrylate and these And derivatives thereof.

The weight average molecular weight of the polymer compound other than the polylactic acid is preferably 10,000 or more and 1,000,000 or less, and more preferably 10,000 or more and 500,000 or less. The molecular weight distribution is preferably 1 or more and 10 or less, more preferably 1 or more and 2 or less, and further preferably 1 or more and 1.5 or less.
The content ratio of the PLLA and the polymer compound other than polylactic acid in the block copolymer of the PLLA and the polymer compound other than polylactic acid is appropriately selected in the range of 1:99 to 99: 1 by mass ratio. Preferably, the range of 10:90 to 90:10 is preferable in that more Sc crystals can be included in the member. The content ratio of PDLA and a polymer compound other than polylactic acid in the block copolymer of PDLA and a polymer compound other than polylactic acid is the same as described above.

The block copolymer can be synthesized by a conventional method. Specifically, for example, these polymers are produced by melt-mixing or solution-mixing at a predetermined ratio according to the block copolymer to be obtained, and then solidifying and further solid-phase polymerization. can do. Alternatively, it can be produced by previously synthesizing a PLLA polymer and sequentially polymerizing and growing a monomer of a polymer compound other than polylactic acid at the molecular terminal. Conversely, it can be produced by synthesizing a polymer compound other than polylactic acid in advance and sequentially polymerizing and growing L-lactic acid units at the molecular ends.

The polymer compound used for the polylactic acid fine particles has a weight average molecular weight of preferably 10,000 or more and 1,000,000 or less, and more preferably 10,000 or more and 500,000 or less. The molecular weight distribution (value of weight average molecular weight / number average molecular weight) is preferably 1 or more, 10 or less, more preferably 1 or more and 5 or less, and further preferably 1 or more and 3 or less. When the polymer compound is a copolymer, the weight average molecular weight may be 20,000 or more and 2,000,000 or less.
In the present invention, values obtained by an exclusion chromatography method using chloroform as a solvent are employed for the weight average molecular weight and molecular weight distribution of the polymer.

-First solvent-
The first solvent is not particularly limited as long as it dissolves the polymer compound to be used, but is preferably a good solvent for the polymer compound to be used. Here, the good solvent for the polymer compound means a solvent having a solubility parameter value close to that of the polymer compound. Preferably, the combination whose difference is 1 or less is mentioned. For example, among polylactic acids, the solubility parameter in a homopolymer of PLLA is 19.0, and the solubility parameter of chloroform is 19.0, so chloroform is a good solvent for the polylactic acid (Japanese Patent Laid-Open No. 2007-332187). See the official gazette).

Good solvents for polymer compounds containing L-lactic acid units and D-lactic acid units include, for example, chloroform, tetrahydrofuran, xylene, toluene, benzene, ethylbenzene, dichloroethane, carbon tetrachloride, trichloroethane, dichloromethane, chlorobenzene, methyl ethyl ketone, dichlorobenzene. , Trichlorobenzene and the like are preferable. One of these may be used, or two or more may be mixed and used as a mixed solvent according to the purpose. Moreover, when setting it as a mixed solvent, in addition to the said solvent, you may mix the poor solvent mixed with 1st solvents, such as methanol and ethanol, for example. The term “mixing” as used herein means that even if left for a long time, it remains in one phase and does not separate.

-Polymer compound solution-
The polymer compound solution is a solution in which the polymer compound is dissolved in the first solvent. Here, “dissolved” refers to a state where the solid content of the polymer compound contained in the polymer compound solution cannot be visually confirmed.
The concentration of the polymer compound in the polymer compound solution is appropriately set according to the types of the polymer compound used, the first solvent and the second solvent, the type of permeable membrane used, the permeation rate, and the like. For example, when a mixture of PLLA homopolymer and PDLA homopolymer is used as the polymer compound, the concentration of the polymer compound is in the range of 0.01% by mass to 50% by mass with respect to the entire polymer compound solution. It is preferable that it is in a range of 0.01% by mass or more and 20% by mass or less.

The polymer compound solution is prepared, for example, by adding the polymer compound to the first solvent at room temperature (25 ° C.) and dissolving the polymer compound in the first solvent by stirring or the like.
When the polymer compound is a mixture, each polymer compound may be mixed after being dissolved in a solvent, or one may be mixed with the solvent and then the other may be added and dissolved. The solution may be prepared at room temperature (25 ° C.), but if desired, the solution may be heated from 25 ° C. to the boiling point of the solvent used.

-Second solvent-
The second solvent is not particularly limited as long as it is a poor solvent for the polymer compound used. Here, the poor solvent for the polymer compound refers to a solvent whose solubility parameter is far from that of the polymer compound. Preferably, the combination whose difference is 5 or more is mentioned. For example, among polylactic acids, the solubility parameter in a homopolymer of PLLA is 19.0, and methanol is 29.7, so methanol is a poor solvent for the polylactic acid (see Japanese Patent Application Laid-Open No. 2007-332187). .
When a mixture of PLLA homopolymer and PDLA homopolymer is used as the polymer compound, and chloroform is used as the first solvent, the second solvent is mixed with the first solvent and used for the polymer compound used. A solvent that is a poor solvent is preferable, and specific examples include methanol, ethanol, 2-propanol, and the like. One of these may be used, or two or more may be mixed and used as a mixed solvent according to the purpose.

In addition, an antioxidant, a stabilizer, a light-proofing agent, a static eliminating agent is added to either one of the first solvent and the second solvent, or both the first solvent and the second solvent, if necessary. Various additives such as a lubricant, a flame retardant, a compatibilizer, a dispersant, and a surfactant may be added. These additives may be used in combination.
When an additive is added to the first solvent and the second solvent, the same additive may be added or different additives may be added. Moreover, the addition amount of the additive added to the 1st solvent and the 2nd solvent may be the same, or may differ.

-Permeation membrane-
The permeable membrane is a membrane having pores having a diameter in the above-described range, which partitions two liquid storage portions in the permeable device. The permeable membrane is not particularly limited as long as the polymer compound solution permeates the permeable membrane through the pores. That is, in the permeable membrane, for example, the pores may penetrate perpendicularly to the film thickness direction in the permeation direction, which is the direction through which the polymer compound solution permeates, or the pores are mesh-like in the permeable membrane. It may be spread in the direction of film thickness, or may be communicated in the film thickness direction by being bent or branched.
Further, the shape of the membrane may be a flat planar membrane, a cylindrical hollow fiber membrane or a tubular membrane. Further, they may be laminated or integrated (bundled).

Here, the diameter of the pores means the diameter of a circle having the same area as that of the cross section having the smallest area among the cross sections of the pores in the cross section perpendicular to the permeation direction of the polymer compound solution.
When the diameter of the pores present in the permeable membrane is in the above range, Sc crystals can be efficiently formed and smaller polylactic acid microparticles can be formed than in the case where the diameter is larger than the above range. When the pore diameter is in the above range, clogging due to crystallization of the polymer compound is less likely to occur than in the case where the diameter is smaller than the above range.
The diameter of the pores present in the permeable membrane is preferably 0.5 nm or more and 1000 nm or less, and more preferably 1 nm or more and 500 nm or less. In addition, it is preferable that the hole whose diameter is larger than the above range does not exist or has a structure in which the polymer compound solution cannot permeate.

The density of the pores existing in the permeable membrane is not particularly limited, and examples thereof include a range in which the porosity (ratio of pores to the total membrane volume) is 10% or more and 90% or less. The shape of the pore is not particularly limited, and may be a shape penetrating linearly in a direction in which the polymer compound solution permeates, may be spread in a mesh shape, or the pore may be bent. Or may be branched.
The material of the permeable membrane does not have to be dissolved or swelled in the solvent used. Specifically, for example, fluororesins such as PTFE (polytetrafluoroethylene) and polyvinylidene fluoride, organic materials such as polyethylene, polypropylene, polycarbonate, and polyethylene terephthalate. Examples thereof include inorganic materials such as materials, alumina, silica and glass, and filter paper made of cellulose.
Although the thickness of a permeable film is not specifically limited, Specifically, the range of 0.1 micrometer or more and 1000 micrometers or less is mentioned, for example, The range of 1 micrometer or more and 500 micrometers or less is more preferable.

<Permeation membrane wetting process>
As described above, prior to the preparation step, the method may further include a permeable membrane wetting step of bringing the permeable membrane into contact with a liquid in advance and replacing the gas in the pores of the permeable membrane with the liquid.
The liquid is not particularly limited, and may be any of the polymer compound solution, the first solvent, the second solvent, and other solvents, preferably the polymer compound solution or the second solvent, A second solvent is more preferred.

<Transmission process>
In the permeation step, the polymer compound solution is permeated through the permeation membrane through the pores at a flow rate in the above range. When the flow rate is in the above range, the polylactic acid microparticles are less likely to aggregate than in the case where the flow rate is larger than the above range, so that the micron size is difficult to be formed, and polylactic acid microparticles having a large proportion of Sc crystals are easily formed. Further, when the flow rate is in the above range, clogging or the like caused by the polymer compound particles growing too much in the pores is less likely to occur than in the case where the flow rate is smaller than the above range. The flow ^{rate, 1 × 10 -3 mL / (} min · cm 2) or more 10000mL / (min · cm ²⁾ or less are ^{preferred, 1 × 10 -2 mL / (} min · cm 2) or more 1000mL / (min · cm ² ) The following is more preferable.

Examples of the permeation method include a method in which a pressure difference is provided between one surface and the other surface of the permeable membrane. The polymer compound solution side can be obtained by physical pressurization or pressurization using centrifugal force. May be applied to the permeable membrane, and the second solvent side may be depressurized. The pressure difference is selected according to the thickness of the permeable membrane, the diameter and density of pores existing in the permeable membrane, the porosity, and the like.
In the permeation step, as described above, it is preferable that the second solvent is in contact with the surface of the permeable membrane on the other liquid container side.
At this time, both or either one of the polymer compound solution and the second solvent are continuously or intermittently flowed into or out of the respective liquid storage units, thereby continuously or intermittently flowing out of the liquid storage units. Alternatively, polylactic acid fine particles may be produced intermittently.
Through the above steps, polylactic acid fine particles having a large proportion of Sc crystals are formed despite the small particle size. At this time, the shape of the obtained fine particles is preferably spherical, but may be oval or thread-like.

Further, for the polylactic acid Sc crystal fine particles, for example, after forming Sc crystal polylactic acid particles having a large particle diameter, the polylactic acid is dissolved in a good solvent known as a fine particle method of a polymer compound, and then a poor solvent is added thereto. Use a method of mixing to obtain fine particles of a polymer compound (Japanese Patent Laid-Open No. 2004-67883) or a reprecipitation method (Japanese Patent Laid-Open No. 6-79168) of dropping a polymer compound solution into a poorly stirred poor solvent. Then, the produced Sc crystal will be decomposed again, and there is a problem that the efficiency is poor and the ratio of the Sc crystal cannot be maintained. However, when the production method of the present invention is used, polylactic acid fine particles having both a small particle size and a large Sc crystal ratio can be obtained.

<Other processes>
The manufacturing method of the polylactic acid microparticles | fine-particles in this invention may have another process as needed other than the said process.
As other steps, for example, a step of synthesizing a polymer compound, a step of purifying raw materials (that is, a first solvent, a polymer compound, and a second solvent) performed prior to the preparation step, In the case where polylactic acid is used as the molecular compound, a step of antioxidation treatment or hydrolysis resistance treatment by mixing vitamin E or carbodiimide with purified polylactic acid may be mentioned. In addition, a fractionation step such as centrifugation for separating the polylactic acid fine particles obtained by the permeation step according to size performed after the permeation step, ultrasonic treatment for dispersing the polylactic acid fine particles, and polylactic acid fine particles Examples include a known process such as freeze-drying for drying without agglomeration, and a process for subjecting the obtained polylactic acid fine particles to an antioxidant treatment or an antibacterial treatment. Furthermore, the process of surface-treating the surface of the obtained polylactic acid fine particle with chemical modifiers, such as a silane coupling agent, is also mentioned. Alternatively, a hydrophilic molecule such as polyethylene glycol is physically adsorbed on the surface of the polylactic acid fine particles to make it hydrophilic (“hydrophobization” when a hydrophobic molecule is used instead of a hydrophilic molecule), etc. Is mentioned. Moreover, the process etc. which perform the surface treatment of polylactic acid microparticles | fine-particles with surfactant and a dispersing agent containing both these components (namely, a hydrophilic component and a hydrophobic component) are also mentioned.

<Polylactic acid microparticle production equipment>
FIG. 1 is a schematic view schematically showing an example of an apparatus used in the method for producing the polylactic acid fine particles.
The manufacturing apparatus 100 of FIG. 1 includes a first reservoir 12 (one liquid storage unit) that stores the polymer compound solution 10 and a second reservoir 22 (the other liquid storage unit) that stores the second solvent 20. And adjusting the pressure in the manufacturing apparatus 100, the permeable membrane 30 having the above-mentioned diameter of the pores, the third reservoir 40 storing the second solvent 20 discharged from the second reservoir 22, and Pressure adjusting means 50 for reducing pressure and pressure reducing means 60 for reducing the pressure inside the manufacturing apparatus 100.
The first reservoir 12 and the second reservoir 22 are partitioned by a permeable membrane 30, and the first reservoir 12, the second reservoir 22, and the permeable membrane 30 constitute a permeation device.

The polymer solution 10 stored in the first reservoir 12 and the second solvent 20 stored from the second reservoir 22 through the discharge pipe 44 to the lower portion of the third reservoir 40 (the liquid level shown in FIG. 1) These are stored in direct contact with one surface and the other surface of the permeable membrane 30, respectively. The polymer compound solution 10 and the second solvent 20 are in direct contact inside the pores of the permeable membrane 30.

When the decompression means 60 is operated, the inside of the manufacturing apparatus 100 is decompressed to a pressure adjusted by the pressure adjustment means 50, and the polymer compound solution 10 permeates the permeable membrane 30. Specifically, first, the air in the third reservoir 40 is discharged from the discharge port 46 to the discharge pipe 54, whereby the pressure in the third reservoir 40 is reduced. On the other hand, the first reservoir 12 is provided with an opening 16, and the outside air is taken into the first reservoir 12 through the opening 16 so as to be the same as the atmospheric pressure. Due to the pressure difference, the second solvent 20 in the second reservoir 22 is introduced into the third reservoir 40 through the discharge pipe 44 and the polymer compound solution 10 permeates the permeable membrane 30. Then, after the polymer compound dissolved in the polymer compound solution 10 comes into contact with the second solvent 20 in the partitioned space in the pores of the permeable membrane 30 and crystallizes, the crystallized polymer compound becomes the first. 2 Extruded into the reservoir 22 to form crystallized polylactic acid microparticles.

In the manufacturing apparatus 100, the first reservoir 12 and the second reservoir 22 are provided with temperature adjusting means 18 and 28, respectively, and stored by flowing a liquid inside the temperature adjusting means 18 and 28. The temperature of the polymer compound 10 and the second liquid 20 can be adjusted.
As described above, polylactic acid fine particles are produced using the production apparatus 100 of FIG. However, the present invention is not limited to the manufacturing method using the manufacturing apparatus 100.

[Polylactic acid fine particles]
The polylactic acid microparticles of the present invention include ScLA components of PLLA and PDLA, the ratio of the stereocomplex crystal component to the total crystal component of polylactic acid is 50% or more and 100% or less, and the number average particle Polylactic acid fine particles having a diameter of 0.5 nm or more and less than 1000 nm.

Since the polylactic acid fine particles of the present invention have the above-described configuration, they are highly transparent. That is, since the polylactic acid fine particles have a small particle size and a large proportion of Sc crystals, for example, in a molded body (for example, a film) manufactured using polylactic acid fine particles, light caused by light scattering at the particle interface is used. A decrease in permeability is suppressed. Moreover, since the polylactic acid microparticles | fine-particles of this invention are the said structures, they are suitable for using as a crystal nucleating agent. That is, the polymer compound is uniformly crystallized by promoting the crystallization of the polymer compound by using the above-mentioned polylactic acid fine particles of the present invention having a small particle size and a large percentage of Sc crystal as a crystal nucleating agent. As a result, a tough and highly transparent molded article of a polymer compound can be produced.

The polylactic acid fine particles of the present invention are preferably a homopolymer of polylactic acid fine particles. Here, the polylactic acid homopolymer means that all the structural units constituting the polymer are structural units derived from lactic acid (L-lactic acid and D-lactic acid). That is, the polylactic acid fine particles of the present invention preferably contain a mixture of a PLLA homopolymer and a PDLA homopolymer, and in addition to unavoidable impurities, other components other than the PLLA homopolymer and the PDLA homopolymer It is preferable not to contain. The mass ratio of the homopolymer of PLLA and the homopolymer of PDLA contained in the polylactic acid fine particles is preferably in the range of 10:90 to 90:10.

The number average particle diameter of the polylactic acid fine particles is in the above range, preferably in the range of 0.5 nm to less than 1000 nm, and more preferably in the range of 1 nm to 500 nm. The number average particle size is determined by observing the polylactic acid fine particles with an SEM (scanning electron microscope), measuring the particle size of 100 polylactic acid fine particles, and classifying every 100 nm (0 to 100 nm, 100 to 200 nm, 200 to 200 nm). This is a value obtained by measuring the number of particles corresponding to 300 nm,... Further, the particle diameter means the diameter of a circle when the shape of the projection surface of one polylactic acid fine particle obtained by SEM observation is circular. The particle diameter means the short axis of the ellipse when the shape of the projection surface is distorted in an ellipse, and the thickest part of the fiber when the polylactic acid fine particles are in the form of fibers (fibrous). (That is, the width of the widest portion on the projection plane). In addition, the polylactic acid fine particles are not limited to those having a circular projection surface, an elliptical shape, and a fiber shape as described above, and may be a combination of these. In that case, the diameter of the circle, the minor axis of the ellipse, and the thickness of the fiber are used to obtain the “particle size” as described above.

The polylactic acid fine particles of the present invention are not limited as long as they contain Sc crystals, but the ratio of Sc crystals in all crystal components is preferably 50 to 100%. Specifically, in general, polylactic acid crystals may include Sc crystals of PLLA and PDLA, and α crystals crystallized by PLLA or PDLA alone, and among all the crystal components, Sc crystals are 100 crystals. % (That is, α-crystals are not included) is particularly preferable. When the ratio of Sc crystals in all the crystal components is 50 to 100%, the heat resistance and hydrolysis resistance of the polylactic acid fine particles are improved. Therefore, the polylactic acid fine particles of the present invention are suitable, for example, as raw materials for members that require heat resistance and hydrolysis resistance, and when the polylactic acid fine particles of the present invention are used as a crystal nucleating agent, the melting point ( There is an advantage that post-treatment such as melt kneading at a high temperature of 170 ° C. or higher becomes possible.

Here, the ratio of the Sc crystal is the total value (crystallinity) of the weight fraction (Sc crystal fraction) occupied by the Sc crystal and the weight fraction (α crystal fraction) occupied by the α crystal in the sample. It is a value obtained by dividing the crystal fraction. The α crystal fraction is determined by DSC measurement (differential scanning calorimetry) of polylactic acid fine particles, and the melting peak area (heat of fusion) due to α crystals appearing from 150 ° C. to 180 ° C. is the heat of fusion of 100% α crystal. It is a% value divided by (94 J / g), and the Sc crystal fraction is the melting peak area (heat of fusion) due to the Sc crystal appearing from 190 ° C. to 230 ° C. The heat of fusion of the 100% α crystal (155 J / g) The percentage value divided by.

In the polylactic acid fine particles of the present invention, the ratio of the crystal component to the total component is preferably 10% or more. That is, in general, polylactic acid may contain amorphous components including PLLA and PDLA in addition to the above-mentioned crystal components (that is, Sc crystal component and α crystal component). It is preferable that the ratio of the crystal component is in the above range with respect to the total of Polylactic acid fine particles with a high degree of crystallinity, such as polylactic acid fine particles within the above-mentioned range, are more suitable as crystal nucleating agents. By crystallization using this, the strength and transparency can be further increased. It is possible to produce a molded body having a high height. The proportion of the crystal component is more preferably 10% or more and 100% or less, and further preferably 20% or more and 100% or less.

The method for producing the polylactic acid fine particles of the present invention is not particularly limited. For example, in the conventional method in which the polylactic acid solution is dropped into a poor solvent for the polylactic acid solution and stirred, the Sc crystal is more concentrated as described above. Polylactic acid fine particles containing a large amount and having a small particle diameter cannot be produced.
On the other hand, since the polylactic acid microparticle production method of the present invention described above can produce polylactic acid microparticles having a small particle size and a large proportion of Sc crystals as described above, This is a manufacturing method suitable for manufacturing. In addition, as described above, by using the above-described method for producing polylactic acid fine particles of the present invention and using a mixture of a homopolymer of PLLA and a homopolymer of PDLA as a polymer compound, the ratio of the Sc crystal is 100%. It is possible to produce polylactic acid fine particles having a high degree of crystallinity and thus suitable for producing the polylactic acid fine particles of the present invention. Therefore, it is preferable that the polylactic acid microparticles of the present invention are those produced by the production method of the present invention.

[Crystal nucleating agent]
The crystal nucleating agent of the present invention is composed of the above-mentioned polylactic acid fine particles of the present invention and has a function of promoting the crystallization of the polymer compound. As described above, the polylactic acid fine particles of the present invention are suitable as a crystal nucleating agent, and tough and highly transparent crystals are formed when used as a crystal nucleating agent.

The polymer compound that promotes crystallization using the crystal nucleating agent of the present invention is not particularly limited, and examples thereof include poly-L-lactic acid, poly-D-lactic acid, poly-L-lactic acid, and poly Examples thereof include -D-lactic acid copolymers, copolymers and derivatives containing one or both of poly-L-lactic acid and poly-D-lactic acid as constituents, and mixtures thereof. Also, poly-3-hydroxybutyrate, polyε-caprolactam, polybutylene succinate, polyethylene succinate, or other aliphatic polyester, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, or other Examples thereof include aromatic polyesters, copolymers and derivatives containing one or both of these as constituents, and mixtures thereof. In addition, polyvinyl alcohol, polymethyl methacrylate, polycarbonate, polyethylene adipate, poly-p-vinylphenol, polyvinyl acetate, polyethylene oxide, polyacrylonitrile, polyethylene glycol, polypropylene glycol, polyethylene, polypropylene, poly-1-butene, poly- 4-methyl-1-pentene or other polyolefins, polydimethylsiloxane, polytrimethyl-p-sylphenylenesiloxane or other silicones, fluorine-based polymers such as polyvinylidene, polystyrene, polybutylene adipate terephthalate and the like Examples thereof include copolymers and derivatives containing one or both as constituents, and mixtures thereof.

As a method for promoting crystallization of a polymer compound using the crystal nucleating agent of the present invention, for example, a mixture of the crystal nucleating agent of the present invention and a target polymer compound may be used at a temperature equal to or higher than the melting point of the polymer compound. A method of kneading while heating to a temperature lower than the melting point of the nucleating agent, a method in which the polymer compound is finely divided or powdered by the method of the present invention or other methods, and the crystal nucleating agent at a melting point of both of these. Examples include dry blending (mixing in a fine particle or powder state). Alternatively, a method of mixing the dispersion of the crystal nucleating agent of the present invention and the polymer compound into a dispersion, fine particles or powder by the method of the present invention or other methods can be mentioned. At this time, additives such as an antioxidant, a stabilizer, a light-resistant agent, a static eliminating agent, a lubricant, a flame retardant, a compatibilizer, a dispersant, and a surfactant may be added as necessary.
In addition, after mixing the crystal nucleating agent with the target polymer compound, a molded body may be formed by a drying process, a casting process, a fiberizing process, a film forming process, a uniaxial stretching process, a biaxial stretching process, a heat treatment process, or the like. Good. At this time, if necessary, additives such as antioxidants, stabilizers, light proofing agents, static eliminators, lubricants, flame retardants, compatibilizers, dispersants, surfactants, etc. may be added, The molded product may be subjected to post-treatment such as surface treatment.

[Molded body]
The molded product of the present invention contains the polylactic acid fine particles of the present invention. The polylactic acid fine particles of the present invention may be used alone as a molding resin, or a polymer compound crystallized using a crystal nucleating agent comprising the polylactic acid fine particles may be used as the molding resin. A mixture of the polylactic acid fine particles of the invention and another polymer compound may be used as the molding resin. Moreover, the molded object of this invention may contain other components, such as an additive other than the polylactic acid microparticles | fine-particles of the said this invention, and another high molecular compound.
The other polymer compound is not particularly limited, and examples thereof include a thermoplastic resin, a thermosetting resin, and a soft thermoplastic resin.

As said additive, the filler etc. as a reinforcing agent are mentioned, for example, Both an inorganic filler and an organic filler can be used.
Inorganic fillers include glass fiber, graphite fiber, carbon fiber, carbon nanotube, metal fiber, potassium titanate whisker, aluminum borate whisker, magnesium whisker, silicon whisker, wollastonite, sepiolite, zonolite, elestadite, zeolite, gypsum Fiber, silica fiber, silica-alumina fiber, zirconia fiber, silicon nitride fiber, boron fiber, glass flake, non-swellable mica, graphite, metal foil, talc, clay, mica, sericite, bentonite, kaolin, magnesium carbonate, sulfuric acid Examples include barium, magnesium sulfate, aluminum hydroxide, magnesium oxide, hydrotalcite, magnesium hydroxide, gypsum, and dawsonite.

Examples of the organic filler include natural fiber, para-type aramid fiber, polyazole fiber, polyarylate, polyoxybenzoic acid whisker, polyoxynaphthoyl whisker, and cellulose whisker.
These fillers can be used in the form of fibers, plates or needles. Among these fillers, fibrous inorganic fillers are preferable, and glass fibers are particularly preferable. The aspect ratio of the filler is preferably 5 or more, and more preferably 10 or more. Particularly preferred is 100 or more. In the case of a fibrous filler, the aspect ratio refers to the fiber length divided by the fiber diameter, and in the case of a plate shape, the aspect ratio refers to the length in the long period direction divided by the thickness.

The elastic modulus of the filler is preferably 50 GPa or more.
When a fibrous material is used as the filler, the strength as a single fiber is preferably 200 MPa or more, and more preferably 300 MPa or more. If it is within this range, the obtained molded body has sufficient mechanical properties, and even if the amount of filler to be mixed is small, a sufficient reinforcing effect can be obtained, so the surface of the molded body can be reduced by reducing the amount of filler added. It can be made not to impair the appearance.

Examples of the fibrous filler include those having a fiber diameter in the range of 0.1 μm to 1 mm, and preferably in the range of 1 μm to 500 μm. It is preferable that the aspect ratio (length / diameter) comprising the ratio of the fiber and the diameter is 50 or more. If it is this range, mixing of resin and a fiber can be performed favorably, and also a molded article with a favorable physical property can be obtained by compositing. A more preferred aspect ratio is 100 to 500, and even more preferably 100 to 300.

In addition to the filler, the molded body may contain known additives such as plasticizers, antioxidants, light stabilizers, ultraviolet absorbers, heat stabilizers, lubricants, mold release agents, antistatic agents, One type or two or more types of a colorant including a flame retardant, a foaming agent, a filler, an antibacterial / antifungal agent, a nucleating agent, a dye and a pigment can be contained depending on the purpose.
Further, when the molded body is used as an ion conductor, it may contain a material having ion conductivity, for example, a metal such as lithium or an oxide thereof, a chloride, a fluoride or a complex, together with polylactic acid. Good.

The obtained molded body may be further subjected to a heat treatment step. The heat treatment may be performed in a DSC measurement sample pan and in a DSC furnace, and if it can be set to a constant temperature, it is performed using an oven, press molding machine, air thermostat, oil bath, etc. May be. The heat treatment temperature can be 100 ° C. or higher and 300 ° C. or lower, and more preferably 150 ° C. or higher and 250 ° C. or lower. The heat treatment time is preferably 1 minute to 72 hours, more preferably 1 hour to 24 hours.

Examples of the molding method include molded products such as press molded products, injection molded products, extrusion molded products, vacuum / pressure molded products, and blow molded products. Moreover, as a form of a molded object, a composite body with a film, a sheet | seat, a plate-shaped object, a structure, a nonwoven fabric, a fiber, cloth, another material, etc. are mentioned, for example. Examples of uses of the molded body include agricultural materials, fishing materials, civil engineering / building materials, stationery, medical supplies, various containers, and other molded bodies.

Moreover, the obtained polylactic acid molded body and another member may be combined to form a composite.
Examples of the composite include a laminate in which film-shaped members such as a film and a sheet are stacked on the molded body of the present invention. As a lamination method of the molded body of the present invention and another member in the form of a film, a laminate method in which both are bonded by heating and pressing, or the molded body of the present invention and another member in the form of a film are bonded together. The method etc. are mentioned.
In the bonding of the molded body of the present invention and another film-shaped member, an adhesive may be applied to at least one of the molded body of the present invention and the other film-shaped member.

The shape of the other member used for compounding with the molded article of the present invention is not limited to a film shape, and may be a lump shape such as a pellet shape or a block shape.
The shape of the molded body of the present invention is not particularly limited, and may be a film shape such as a film shape or a sheet shape, or may be a lump shape such as a pellet shape or a block shape.
In addition, the shape of the molded body of the present invention and the shape of other members may be the same or different.

Molding can be performed by a conventional method, but the molding method is not particularly limited. As an example of the forming method, a specific example of the method for producing a film comprising the polylactic acid fine particles of the present invention will be described below, but the method is not limited thereto.

<An example of a method for producing a film comprising polylactic acid fine particles>
Specifically, for example, first, a methanol dispersion of polylactic acid fine particles at room temperature (25 ° C.)
Cast on a Teflon petri dish and dry to remove the solvent. Furthermore, it is dried under reduced pressure for 24 hours to obtain an aggregate of polylactic acid fine particles (reduced pressure condition: 1 Pa).
Next, as shown in FIG. 2, a mold release polyimide film 2 with a thickness of 125 μm is placed on a disk-shaped stainless steel plate 1 with a diameter of 110 mφ × 2 mm, and then a disk with a diameter of 110 mmφ × 0.1 mm in thickness. A 30 mm × 30 mm rectangular window 3 (a stainless steel thin plate with a rectangular window) 3 is placed on a stainless steel plate, and 0.2 g of the polylactic acid fine particle aggregate is placed in the rectangular window. A polyimide film 5 for release having a thickness of 125 μm is placed thereon, and a disk-shaped stainless steel plate 6 having a diameter of 110 mmφ × 2 mm is further placed thereon.
These entire laminates were placed between upper and lower plates in a press machine (manufactured by Baldwin Co., Ltd.) installed in a vacuum chamber at room temperature (25 ° C.), and reduced in pressure with a rotary pump to 1.33 × 10 ⁻¹ Pa. Close the space between the upper and lower press plates as much as possible so that no stress is applied, heat to 200 ° C, hold at 200 ° C for 5 minutes, and then turn off the heater power while pressing at a pressure of 4.5 MPa (cylinder pressure 60 Pa) And slowly cool to room temperature under reduced pressure. Thereafter, the vacuum chamber is opened and the formed film 4 is taken out.

The molded body may be, for example, directly rolled (stretched) the aggregate of the polylactic acid fine particles, or the molded body obtained by the above method is uniaxially stretched or simultaneously biaxially stretched, sequentially biaxially stretched, You may perform the extending | stretching process which provides molecular orientation, such as roll rolling (stretching) and extrusion stretching.

Examples of uses of the molded body include structural members, building materials, joinery materials, construction temporary materials, various automobile parts, interior materials, sheets, mats, and the like that require strength and heat resistance, in addition to the above uses. The molded body of the present invention is suitably used for a wide range of applications, and its application range is wide.
Hereinafter, particularly preferred embodiments of the molded body of the present invention will be described.

<Synthetic fiber>
Similar to general synthetic fiber materials, the molded body of the present invention is easily formed into a single fiber by melt spinning or the like, and can be directly processed into a fiber by a general-purpose apparatus. Furthermore, a modified cross-section fiber can be easily formed by selecting a spinning die.
Moreover, you may perform the extending | stretching process which provides molecular orientation, such as uniaxial stretching, roll rolling (stretching), and extrusion stretching, with respect to these fibers.
The diameter of the synthetic fiber of the present invention is arbitrarily selected in the range of 0.1 μm to 1 mm, preferably in the range of 1 μm to 500 μm.
Moreover, you may manufacture a new molded object using the said synthetic fiber. Examples of this embodiment include a woven fabric obtained from the synthetic fiber of the present invention, a molded body using a nonwoven fabric, and the like.

<Porous body>
The molded body of the present invention may be a polymer mixture containing polylactic acid, a molded body, or a porous body obtained by decomposing and removing components other than polylactic acid from synthetic fibers.
For example, the porous body is prepared / manufactured by the molded body of the present invention, and then at least its components other than polylactic acid contained in the molded body are subjected to acid etching treatment or ultrasonic treatment in a solvent. It is obtained by removing a part.
A portion where components other than polylactic acid are removed becomes voids, and a porous body of polylactic acid having a large number of fine voids inside is formed. As other means for removing the component, either the acid etching treatment or the ultrasonic treatment may be used, or a combination thereof may be performed. When combining a plurality of means, the order is arbitrary. Moreover, you may perform these several processes simultaneously.
Moreover, you may perform the extending | stretching process which provides molecular orientation, such as uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, roll rolling (stretching), and extrusion stretching, with respect to the obtained porous body. These stretching processes may be performed before decomposing and removing components other than the polylactic acid.

[Surface modifier]
The surface modifier of the present invention comprises the polylactic acid fine particles of the present invention.

By using the surface modifier of the present invention containing the polylactic acid fine particles of the present invention to form a layer (also referred to as “surface modified layer”) that covers all or part of the surface of various substrates, surface modification is performed. The quality layer functions as a protective layer, and the surface of the base material can be modified to a surface excellent in wear resistance and scratch resistance.
Furthermore, the polylactic acid fine particles of the present invention have a large proportion of Sc crystals. Therefore, many Sc crystals of polylactic acid are attached to the substrate surface. It is known that the Sc crystal of polylactic acid is superior in hydrolysis resistance compared to normal α crystal and amorphous [H. Tsuji, Polymer, Volume 41, pp.3621 (2000)]. Therefore, the surface modified layer functions as a protective layer excellent in hydrolysis resistance in addition to abrasion resistance and scratch resistance. In other words, by using the surface modifier of the present invention, the substrate surface can be modified to a surface excellent in hydrolysis resistance.
Since the polylactic acid fine particles of the present invention contain Sc crystals at a high rate, they can be suitably used as such a surface modifier.

Further, the polylactic acid fine particles of the present invention have a small particle size and are nano-order less than 1000 nm. Therefore, a surface-modified layer having a thinner layer thickness than the conventional surface-modified layer formed of micro-order polylactic acid particles containing Sc crystals but having a particle size of 1 μm or more is formed on the substrate surface. can do. By making the surface modification layer formed on the substrate surface thinner, it is possible to make the layer difficult to peel off from the substrate surface.

In particular, if the base material to which the surface modifier is applied is a thin film member such as a film or sheet containing polylactic acid, it has better affinity with polylactic acid than the surface modifier. A protective layer adhered more firmly can be formed.
Currently, silicone coatings used to modify the surface of polyethylene terephthalate are used as coating agents for polylactic acid films and sheets. It has the problem that it ends up. In this respect, the polylactic acid fine particles of the present invention can be more suitably used as a surface modifier that is difficult to peel off.
In addition, since the polylactic acid Sc crystal has a higher melting point and better mechanical strength than ordinary α crystal and amorphous, the layer formed using the surface modifier of the present invention has heat resistance and scratch resistance. Furthermore, it becomes an excellent surface protective layer.

Thus, if a layer containing Sc crystals can be formed on the surface of the substrate with the surface modifier comprising the polylactic acid fine particles of the present invention, the entire polylactic acid molded body is made to be Sc crystals. It is possible to impart excellent performance unique to Sc crystal such as hydrolysis resistance, heat resistance, scratch resistance, etc. to the base material in a much smaller amount, and it is industrially useful from the viewpoint of manufacturing cost. .

The surface modifier of the present invention is not particularly limited as long as it comprises the polylactic acid fine particles of the present invention,
It may be a fine particle aggregate composed only of the polylactic acid fine particles of the present invention, or may be a polylactic acid fine particle dispersion composition comprising a dispersion medium in which the polylactic acid fine particles of the present invention are further dispersed. .
The dispersion medium for dispersing the polylactic acid fine particles of the present invention may be a liquid, a gel, or an aerosol. When the dispersion medium is a liquid or a gel, examples of the liquid and the liquid constituting the gel include the first solvent and the second solvent. As described above, the first solvent is a good solvent for a polymer compound containing an L-lactic acid unit and a D-lactic acid unit. The second solvent is a poor solvent for a polymer compound containing an L-lactic acid unit and a D-lactic acid unit. These solvents may be used alone or in combination of two or more.
Among these, from the viewpoint of maintaining the function of the polylactic acid fine particles of the present invention and improving the dispersibility of the polylactic acid fine particles, it is preferable to use the second solvent.

In addition, the surface modifier of the present invention may contain a surfactant in order to improve the dispersibility of the polylactic acid fine particles, and the adhesive may be used so that the polylactic acid fine particles easily adhere to the substrate surface. Or an adhesive, a solvent, and the like. Further, it may contain various additives such as an ultraviolet absorber and an antioxidant.

The method of using the surface modifier of the present invention is not particularly limited, and for example, a method of directly spreading the polylactic acid fine particles of the present invention on the surface of a substrate may be used, or the polylactic acid fine particles of the present invention may be dispersed in a dispersion medium. Alternatively, the dispersion may be applied (coated) to the substrate surface. Examples of the method of applying (coating) the dispersion onto the substrate surface include spin coating, wire bar coating, blade coating, dip coating, and spray coating.

As described above, the form of the surface modifier of the present invention may be a fine particle aggregate, a spraying agent such as an aerosol, or a surface coating agent such as a fine particle dispersion or a fine particle dispersion gel.

Although it does not specifically limit as a base material which adheres the surface modifier of this invention, The base material comprised using the following compound is mentioned.
For example, poly-L-lactic acid, poly-D-lactic acid, a copolymer of poly-L-lactic acid and poly-D-lactic acid, a copolymer containing at least one of poly-L-lactic acid and poly-D-lactic acid as a constituent component Examples include polymers or derivatives thereof, and compounds derived from polylactic acid such as a mixture thereof.
In addition to the above polylactic acid-derived compounds, poly-3-hydroxybutyrate, polyε-caprolactam, polybutylene succinate, polyethylene succinate, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, and other fats Polyester, aromatic polyester, polyvinyl alcohol, polymethyl methacrylate, polycarbonate, polyethylene adipate, poly-p-vinylphenol, polyvinyl acetate, polyethylene oxide, polyacrylonitrile, polyethylene glycol, polypropylene glycol, polyethylene, polypropylene, poly-1-butene Polyolefins such as poly-4-methyl-1-pentene, polydimethylsiloxane, polytrimethyl - silicones such as silphenylene siloxanes, fluorinated polymers such as poly fluoride vinylidene polystyrene, may be used polybutylene adipate terephthalate.
In addition, you may comprise a base material with the copolymer which copolymerized the said compound, its derivative (s), and these mixtures.
Furthermore, you may use the base material comprised by inorganic materials, such as engineering plastics, such as a polyimide, various metal materials, and ceramics.

The shape of the substrate is not particularly limited as long as the surface modifier of the present invention can be attached, and may be a film shape, a film shape such as a sheet shape, a pellet shape, a block shape, or the like. Any shape such as a lump shape may be used.

The surface of the substrate is subjected to plasma treatment, corona discharge treatment, chemical modification treatment before application of the surface modifier so that the polylactic acid fine particles of the present invention contained in the surface modifier are easily attached to the substrate surface. Further, surface modification treatment such as acid etching treatment or ultrasonic treatment may be performed.
Alternatively, the surface can be covered with polylactic acid fine particles by bringing the powder into contact with the surface of the substrate. At this time, in order to make the polylactic acid fine particles easily adhere to the surface of the base material, a solvent or an adhesive may be appropriately applied.
Further, the polylactic acid fine particles of the present invention may be previously formed into a film shape such as a film shape or a sheet shape and laminated on a substrate.

In this way, various known materials such as roll molding, injection molding, blow molding, etc., in addition to the press molding used for the above film molding, are applied to the molded body in which the surface modifier of the present invention is adhered to various base materials. A molding method may be applied. Furthermore, you may perform the extending | stretching process which provides molecular orientation, such as uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, roll rolling (stretching), and extrusion stretching.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist.

[Example 1]
Using the production apparatus 100 shown in FIG. 1, polylactic acid fine particles were produced as follows.

<Manufacture of polylactic acid fine particles>
-Preparation process-
As the polymer compound, PLLA (manufactured by Mitsui Chemicals, Inc., product name: Lacia, Mw = 2.3 × 10 ⁵ ) and PDLA (manufactured by PURAC, Mw = 2.3 × 10 ⁵ ) were used. The above PLLA and PDLA are dissolved in dichloromethane, reprecipitated with methanol to remove oligomers, and then subjected to an antioxidant treatment (specifically, treatment with addition of vitamin E or carbodiimide) and purified PLLA and Purified PDLA was obtained.
Purified PLLA and purified PDLA are dissolved in chloroform so that each concentration is 0.5% by mass (that is, purified PLLA and purified PDLA are in equal amounts), and a chloroform solution of PLLA and PDLA (polymer compound solution) 1) was obtained.
Methanol was used as the second solvent.
The solubility parameters of polylactic acid, chloroform and methanol are 19.0, 19.0 and 29.7 (Japanese Patent Laid-Open No. 2007-332187).

-Contact process-
As the permeable membrane 30, a membrane filter having a pore diameter (pore diameter) of 100 nm (manufactured by Advantech, product name: hydrophilic PTFE type membrane filter (product number H010A), material: PTFE, film thickness: 35 μm, porosity: 71% ) Was used. Note that the pores in the membrane filter are not linear but have a network-like shape in the membrane filter.
By injecting methanol from the reservoir 22 side of the permeable membrane 30 and moistening the permeable membrane 30 with methanol, injecting the polymer compound solution 1 into the reservoir 12 and injecting methanol into the reservoir 22, The gas present in the pores of the permeable membrane 30 was removed, and the polymer compound solution 1 and methanol were brought into direct contact.

-Transmission process-
Next, the decompression means 60 was operated. At this time, the pressure in the manufacturing measure 100 was adjusted by the pressure adjusting means 50 so that the polymer compound solution 1 permeates the permeable membrane 30 at a flow rate of 0.41 mL / (min · cm ² ).
Thus, polylactic acid fine particles 1 were obtained.

<Evaluation of polylactic acid fine particles>
The resulting dispersion of polylactic acid fine particles 1 dispersed in methanol is dropped on a cleaved mica plate and dried, and the polylactic acid fine particles 1 are observed with an SEM (manufactured by Hitachi High-Tech, model number: S-4800). It was. The resulting image is shown in FIG.

Table 2 shows the results obtained by the above method for the number average particle diameter of the polylactic acid fine particles 1, the ratio of Sc crystals in all crystal components, and the ratio of all crystal components in all components.
In addition, about the DSC measurement for calculating | requiring the said ratio of Sc crystal | crystallization, specifically, the methanol dispersion liquid of the obtained polylactic acid microparticles | fine-particles 1 was dried (drying temperature 25 degreeC), and a DSC measuring apparatus (made by Perkin Elmer Co., Ltd.). , Model number: Pyris 1 DSC), and the temperature was increased from 100 ° C. to 240 ° C. at a rate of temperature increase of 10 ° C./min. Based on the Sc crystal fraction determined from the melting peak area attributed to the Sc crystal appearing from 200 ° C. to 225 ° C. and the α crystal fraction determined from the melting peak area attributed to the α crystal appearing from 150 ° C. to 180 ° C. Then, the “ratio of Sc crystal” in all crystal components and the “ratio of all crystal components” (crystallinity) in the sample were calculated.

[Example 2]
Polylactic acid microparticles 2 were obtained in the same manner as polylactic acid microparticles 1 except that the flow rate was 0.82 mL / (min · cm ² ).
The obtained polylactic acid fine particles 2 were observed by SEM in the same manner as the polylactic acid fine particles 1. An image obtained as a result of the observation is shown in FIG. 4a. Also, a low-magnification SEM image at a position different from that in FIG. 4a is shown in FIG. 4b, and a high-magnification SEM image is shown in FIG. 4c.
Similarly to the polylactic acid fine particles 1, the number average particle diameter of the polylactic acid fine particles 2, the ratio of Sc crystals in all the crystal components, and the ratio of all crystal components in all the components were determined. The results are shown in Table 2. Furthermore, the particle size distribution of the polylactic acid fine particles 2 is shown in FIG.

-Production of film-
Using the obtained polylactic acid microparticles 2, a film 1 was obtained by the same method as in one example of a method for producing a film composed of the polylactic acid microparticles (FIG. 2).
The obtained film 1 was a self-supporting film, and had practical strength without being broken even if it was held in the hand. The film 1 was measured for haze (cloudiness, unit:%) at room temperature (25 ° C.) according to JIS K7105 “Testing method for optical properties of plastics”. As a result, it was 12.5.
Further, the film 1 was placed on the optical path of Hitachi U-1800, and the transmittance was measured in the range of 250 to 800 nm at room temperature. Table 1 shows the measured values.

From these results, it was found that the film produced using the polylactic acid fine particles of the present invention was excellent in transparency.

[Example 3]
As the permeable membrane 30, an alumina porous membrane (manufactured by Whatman, product name: Anodisc Membrane Filter 25, material: alumina, film thickness: 60 μm, porosity: 25 to 50%) is used instead of a membrane filter, and the flow rate is 2 Polylactic acid microparticles 3 were obtained in the same manner as polylactic acid microparticles 1 except that × 10 ⁻² mL / (min · cm ² ).
The pores of the alumina porous membrane have a diameter of 200 nm on the surface on the first reservoir 12 side and a diameter of 20 nm on the surface on the second reservoir 22 side, and the second from the surface on the first reservoir 12 side. The diameter decreases toward the surface on the reservoir 22 side. The pores of the alumina porous membrane have a shape that penetrates linearly in the direction in which the polymer compound solution permeates.

The obtained polylactic acid fine particles 3 were observed by SEM in the same manner as the polylactic acid fine particles 1. An image obtained as a result of the observation is shown in FIG. Moreover, the SEM image in the position different from FIG. 5a is shown in FIG. 5b.
Similarly to the polylactic acid fine particles 1, the number average particle diameter of the polylactic acid fine particles 3, the ratio of Sc crystals in all the crystal components, and the ratio of all crystal components in all the components were determined. The results are shown in Table 2. Furthermore, the particle size distribution of the polylactic acid fine particles 3 is shown in FIG.

[Comparative Example 1]
While stirring at 80 rpm with a fluororesin coat stirrer (length: 1.5 cm, diameter: 4 mm) in 80 mL of methanol, 20 mL of the polymer compound solution 1 was added dropwise at 0.1 mL / sec, and polylactic acid fine particles 4 was obtained. The amounts of these solutions are the same as the volume of the second solvent and the volume of the polymer compound solution used in Example 1, and the same applies to the following Examples and Comparative Examples.
The obtained polylactic acid fine particles 4 were observed by SEM in the same manner as the polylactic acid fine particles 1. An image obtained as a result of the observation is shown in FIG. 6a. Further, a low magnification SEM image at a position different from that in FIG. 6a is shown in FIG. 6b, and a high magnification SEM image is shown in FIG. 6c.
Similarly to the polylactic acid fine particles 1, the number average particle diameter of the polylactic acid fine particles 4, the ratio of Sc crystals in all the crystal components, and the ratio of all crystal components in all the components were determined. The results are shown in Table 2.

[Example 4]
Polylactic acid microparticles 5 were obtained in the same manner as the polylactic acid microparticles 1 except that the flow rate was 4 mL / (min · cm ² ).
The obtained polylactic acid fine particles 5 were observed by SEM in the same manner as the polylactic acid fine particles 1. An image obtained as a result of the observation is shown in FIG. Further, a low-magnification SEM image at a position different from that in FIG. 7a is shown in FIG. 7b, and a high-magnification SEM image is shown in FIG. 7c.
Similarly to the polylactic acid fine particles 1, the number average particle diameter of the polylactic acid fine particles 5, the ratio of Sc crystals in all the crystal components, and the ratio of all crystal components in all the components were determined. The results are shown in Table 2. Furthermore, the particle size distribution of the polylactic acid fine particles 5 is shown in FIG. 7d.

[Example 5]
Polylactic acid microparticles 6 were obtained in the same manner as the polylactic acid microparticles 1 except that the flow rate was 0.28 mL / (min · cm ² ).
The obtained polylactic acid fine particles 6 were observed by SEM in the same manner as the polylactic acid fine particles 1. An image obtained as a result of the observation is shown in FIG. 8a. Further, a low-magnification SEM image at a position different from that in FIG. 8a is shown in FIG. 8b, and a high-magnification SEM image is shown in FIG. 8c.
Similarly to the polylactic acid fine particles 1, the number average particle diameter of the polylactic acid fine particles 6, the ratio of Sc crystals in all the crystal components, and the ratio of all crystal components in all the components were determined. The results are shown in Table 2. Furthermore, the particle size distribution of the polylactic acid fine particles 6 is shown in FIG.

[Example 6]
As the permeable membrane 30, instead of the membrane filter, a membrane filter having a pore diameter (pore diameter) of 500 nm (manufactured by Advantech, product name: hydrophilic PTFE type membrane filter (product number H050A), material: PTFE, film thickness: Polylactic acid microparticles 7 were obtained in the same manner as polylactic acid microparticles 1 except that 35 μm and porosity: 79%) were used, and the flow rate was 0.41 mL / (min · cm ² ).

In the same manner as the polylactic acid fine particles 1, the obtained polylactic acid fine particles 7 were observed by SEM. An image obtained as a result of the observation is shown in FIG.
Similarly to the polylactic acid fine particles 1, the number average particle diameter of the polylactic acid fine particles 7, the ratio of Sc crystals in all the crystal components, and the ratio of all crystal components in all the components were determined. The results are shown in Table 2.

[Example 7]
Purified PLLA and purified PDLA are dissolved in chloroform so that each concentration is 0.1% by mass (that is, purified PLLA and purified PDLA are in equal amounts), and a chloroform solution of PLLA and PDLA (polymer compound solution) Polylactic acid microparticles 8 were obtained in the same manner as the polylactic acid microparticles 5 except that 2) was obtained.
In the same manner as the polylactic acid fine particles 1, the obtained polylactic acid fine particles 8 were observed by SEM. An image obtained as a result of the observation is shown in FIG.
The number average particle diameter of the polylactic acid fine particles 8 was determined in the same manner as the polylactic acid fine particles 1. The results are shown in Table 2.

[Example 8]
Polylactic acid fine particles 9 were obtained in the same manner as the polylactic acid fine particles 8, except that the flow rate was 0.82 mL / (min · cm ² ).
In the same manner as the polylactic acid fine particles 1, the obtained polylactic acid fine particles 9 were observed by SEM. An image obtained as a result of the observation is shown in FIG.
The number average particle size of the polylactic acid fine particles 9 was determined in the same manner as the polylactic acid fine particles 1. The results are shown in Table 2.

[Example 9]
Polylactic acid microparticles 10 were obtained in the same manner as the polylactic acid microparticles 8 except that the flow rate was 0.21 mL / (min · cm ² ).
In the same manner as the polylactic acid fine particles 1, the obtained polylactic acid fine particles 10 were observed with an SEM. An image obtained as a result of the observation is shown in FIG.
The number average particle diameter of the polylactic acid fine particles 10 was determined in the same manner as the polylactic acid fine particles 1. The results are shown in Table 2.

From the results shown in Table 2, in the examples, since the polylactic acid fine particles are produced using the production method of the present invention, the ratio of the Sc crystal is small although the particle diameter is small as compared with the comparative example. It can be seen that large polylactic acid fine particles are formed. That is, it can be seen that the polylactic acid fine particles obtained in the examples have a Sc crystal ratio of 100%, and both a small particle size and a high Sc crystal ratio are compatible. Moreover, it turns out that the polylactic acid microparticles | fine-particles with a small particle diameter obtained in the Example have the high light transmittance of the obtained film.

Also, from the SEM images of Examples 1 to 9 and Comparative Example 1, the polymer compound solution 1 was dropped into methanol and mixed with the membrane filter or alumina porous membrane rather than the particles shown in the SEM image of Comparative Example 1. It turned out that the particle | grains of the Example which permeate | transmitted the particle | grains of uniform size were obtained.

The SEM images of Examples 1 to 9 and Comparative Example 1 are all observed by casting the solution that permeated the membrane onto a mica plate. In taking the SEM image, in order to observe nanometer-sized particles, the metal vapor deposition treatment used in normal SEM observation was not performed. Therefore, in order to prevent damage to the sample during sample observation, the acceleration voltage was lowered to 500 V for observation. The SEM images of Examples 1 to 9 and Comparative Example 1 were taken at 10,000 times at low magnification and 70,000 times at high magnification.

Next, using a differential scanning calorimetry (DSC) device (Perkin Elmer, Pyris 1 DSC), it was examined whether the obtained crystals contained Sc crystals. The DSC measurement was performed on the film 1 obtained in Example 2 and the polylactic acid fine particles 6 obtained in Example 5. The measurement conditions were a temperature increase rate of 10 ° C./min and a scanning temperature range of 30 to 250 ° C. in a nitrogen stream. DSC melting curve was obtained. The temperature and heat quantity were corrected by measuring the melting point and heat of fusion of standard samples (indium and tin). The obtained DSC melting curve is shown in FIG.
Of the two curves shown in FIG. 13, the lower curve (curve A) is the DSC melting curve for film 1 of Example 2, and the upper curve (curve B) is the polylactic acid microparticles of Example 5. 6 is a DSC melting curve for 6.

From the studies so far, it is known that the α crystal peak is observed at 170 ° C. and the Sc crystal peak is observed at 220 ° C. in the DSC measurement of polylactic acid.
On the other hand, the DSC melting curve (curve A and curve B) of the sample obtained by drying the nanoparticles obtained by passing slowly or quickly using a membrane filter shows only the melting peak of Sc crystal in the region around 220 ° C. In the region around 170 ° C., no maximum peak such as a melting peak of Sc crystal was observed.
From this result, it was found that crystallization using a pore membrane is effective for Sc crystallization, and Sc crystal nanoparticles can be obtained efficiently.

[Example 10]
-Surface coating-
As a surface modifier, a dispersion in which polylactic acid fine particles 6 are dispersed in methanol (polylactic acid fine particle concentration of about 0.2% by mass) was prepared.
As a base material for coating the surface modifier, PLLA single product [manufactured by Mitsui Chemicals, Inc., product name: Lacia, Mw = 2.3 × 10 ⁵ ] as a raw material is used. Film 2 (PLLA film) was obtained using the same method as in one example (FIG. 2). On the surface of this

PLLA film

2, 5 mL of a dispersion of polylactic acid fine particles 6 was uniformly applied to the entire surface of the film (front side) little by little and dried, and a surface coat layer was formed. The drying temperature was 25 ° C.

The crystal structure of the obtained surface coat layer was analyzed with a surface X-ray measurement device, Ultimate III, manufactured by Rigaku Corporation. The oblique X-ray incident angle with respect to the film surface at the time of measurement was 0.05 °, which is a total reflection angle (critical angle) of 0.17 ° or less of the polylactic acid crystal. By making X-rays incident at a critical angle or less, an X-ray diffraction profile of only a very surface layer (a depth of about 10 nm from the outermost surface of the film) can be obtained.
The obtained X-ray diffraction profile (WAXD curve) is shown in FIG. In FIG. 14, the horizontal axis represents the X-ray diffraction angle 2θ (deg.), And the vertical axis represents the relative intensity. Only crystal reflections derived from Sc crystals are observed. In addition, although the crystal reflection derived from the normal α crystal is observed at 2θ = 16.5 ° and 18.9 °, it is not observed at all in FIG. 14, and it is understood that the α crystal is not included.

From the above results, it can be seen that the surface coat layer of Sc crystal is formed by applying the polylactic acid fine particles of the present invention to the surface of the single PLLA film. This indicates that the polylactic acid fine particles of the present invention are suitable as a surface modifier.

The disclosure of Japanese application 2010-108575 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

1 and 6 Disc-shaped

stainless steel plate

2 and 5 Mold release polyimide film 3 Stainless steel thin plate with rectangular window 4 Film 10 Polymer compound solution 12 First reservoir 16 Opening portions 18 and 28 Temperature adjusting means 20 Second solvent 22 Second Reservoir 30 Permeation membrane 40

Third reservoir

44, 54 Discharge pipe 46 Discharge port 50 Pressure adjusting means 60 Depressurizing means 100 Manufacturing apparatus

Claims

In a permeation device having two liquid containing portions partitioned by a permeable membrane having pores having a diameter of 0.5 nm or more and 1000 nm or less, a structural unit derived from L-lactic acid and D-lactic acid are provided in one liquid containing portion. A polymer compound solution obtained by dissolving a polymer compound containing a derived structural unit in a first solvent is accommodated, and a second solvent that is a poor solvent for the polymer compound is accommodated in the other liquid container. A preparation process;
The polymer solution accommodated in the liquid accommodating portion of the one, 1 × 10 -3 mL / ( min · cm 2) or more 10000mL / (min · cm 2) be transmitted through said permeable membrane at a flow rate not less than And a permeation step for bringing the polymer compound solution into contact with the second solvent.
2. The polylactic acid fine particles according to claim 1, further comprising a permeation membrane wetting step of bringing the permeation membrane into contact with a liquid in advance and substituting the gas in the pores of the permeation membrane with the liquid prior to the preparation step. Manufacturing method.
The method for producing polylactic acid microparticles according to claim 1 or 2, wherein the polymer compound is a mixture of a poly-L-lactic acid homopolymer and a poly-D-lactic acid homopolymer.
The component of the stereocomplex crystal of poly-L-lactic acid and poly-D-lactic acid is 50% or more and 100% or less with respect to the total crystal component of polylactic acid, and the number average particle size is 0.5 nm or more and less than 1000 nm Polylactic acid fine particles.
The polylactic acid fine particles according to claim 4, wherein the ratio of the total crystal component to the total of the amorphous component of polylactic acid and the total crystal component is 10% or more.
A crystal nucleating agent comprising the polylactic acid fine particles according to claim 4 or 5.
A molded product comprising the polylactic acid fine particles according to claim 4 or 5.
A surface modifier comprising the polylactic acid fine particles according to claim 4 or 5.