JP2015203087A - Stereocomplex polylactic acid resin composition and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stereocomplex polylactic acid resin composition which has a high crystal melting peak temperature, a narrow half-width, and high heat resistance.SOLUTION: The stereocomplex polylactic acid resin composition has a stereocomplex formation rate of 0.5 to 2.0%, an optical purity of 96.0 to 99.9%, an organic solvent content of 1 ppm or less, a metal catalyst content of 5 ppm or less, and a number average molecular weight of 100,000 or more. The method for producing the stereocomplex polylactic acid resin composition comprises: an L-lactide ring-opening polymerization step of contacting a raw material containing an L-lactide with a compressible liquid to obtain a polymer; a D-lactide ring-opening polymerization step of contacting a raw material containing a D-lactide with a compressible liquid to obtain a polymer; and a mixing step of obtaining a mixture of poly-L-lactic acid and poly-D-lactic acid by contacting and mixing the poly-L-lactic acid and the poly-D-lactic acid, which are left in contact with the compressible liquid, in a state where more of the compressible liquid ia added.

Description

  The present invention relates to a stereocomplex polylactic acid resin composition and a method for producing the same.

  In recent years, from the viewpoint of protecting the global environment, biodegradable polymers that are decomposed in the natural environment have attracted attention and are being studied all over the world. As the biodegradable polymer, polyhydroxybutyrate, polycaprolactone, aliphatic polyester, and polylactic acid are known. These polymers can be melt-molded and are expected as versatile polymers.

  Among them, lactic acid or lactide, which is a raw material of polylactic acid, can be produced from natural products, and the polylactic acid is highly transparent, tough and easy in the presence of water. Because it is hydrolyzed and decomposes without polluting the environment even when discarded, it is considered to be used not only as a biodegradable polymer but also as a general-purpose polymer that is friendly to the global environment. .

  However, the melting point of the polylactic acid is about 170 ° C., and it cannot be said that the heat resistance is sufficient for use as a general-purpose polymer, and further improvement in heat resistance is desired.

  On the other hand, poly-L-lactic acid (hereinafter also referred to as PLLA) which is a polymer of L-form lactic acid and poly-D-lactic acid (hereinafter also referred to as PDLA) which is a polymer of D-form lactic acid are in solution or in a molten state. It is known to produce a stereocomplex polylactic acid by mixing in For example, a method of producing the stereocomplex polylactic acid by mixing the PLLA and the PDLA using an ester compound and a crystal nucleating agent is disclosed (for example, see Patent Document 1).

  A method for producing stereocomplex polylactic acid by using PLLA obtained by polymerizing L-lactide and PDLA obtained by polymerizing D-lactide using supercritical carbon dioxide as a solvent and mixing them Is disclosed (for example, see Patent Document 2).

  These stereocomplex polylactic acids exhibit a higher melting point and higher crystallinity than the above-mentioned PLLA or PDLA single polylactic acid. Therefore, in order to obtain polylactic acid having high heat resistance, stereocomplex polylactic acid has attracted attention and has been studied.

  However, in these disclosed methods, a large amount of D-form lactic acid that does not exist in nature is used, and it cannot be said that it is practically satisfactory in terms of safety and economy.

  In order to improve the heat resistance, it is necessary to mix a substantial amount of the PDLA with the PLLA and to improve the heat resistance by a synergistic effect of both. Therefore, in the study of stereocomplex polylactic acid for the purpose of improving heat resistance, it has not been easy to solve safety and economic problems at the same time.

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention provides a stereocomplex polylactic acid resin having a high crystal melting peak temperature, a narrow half-value width, and high heat resistance even when any of a small amount of D-form lactide and a small amount of poly-D-lactic acid is used. An object is to provide a composition.

  Means for solving the problems are as follows. That is, the stereocomplex polylactic acid resin composition of the present invention has a stereocomplex formation rate of 0.5% to 2.0% and an optical purity of 96.0% to 99.9%. Features.

  According to the present invention, the above-mentioned problems can be solved and the above-mentioned object can be achieved, and the crystal melting peak can be obtained by using any of a small amount of D-form lactide and a small amount of poly-D-lactic acid. A stereocomplex polylactic acid resin composition having a high temperature, a narrow half-value width, and high heat resistance can be provided.

FIG. 1 is a general phase diagram showing the state of a substance with respect to temperature and pressure. FIG. 2 is a phase diagram for defining the range of the compressible fluid in the present embodiment. FIG. 3 is a system diagram showing an example of the polymerization process. FIG. 4 is a system diagram showing an example of the polymerization process. FIG. 5A is a system diagram illustrating an example of a mixing process. FIG. 5B is a system diagram showing an example of the mixing step. FIG. 6 is a system diagram showing an example of the mixing step. FIG. 7 is a diagram illustrating an example of a DSC measurement result. FIG. 8 is a diagram illustrating an example of a DSC measurement result.

(Stereo complex polylactic acid resin composition)
The stereocomplex polylactic acid resin composition of the present invention contains at least poly-L-lactic acid and poly-D-lactic acid, and further contains other components as necessary.

The stereocomplex polylactic acid resin composition has a stereocomplex formation rate of 0.5% to 2.0% and an optical purity of 96.0% to 99.9%. The optical purity is more preferably 97.0% or more and 99.9% or less. The stereocomplex polylactic acid resin composition exhibiting this property is excellent in heat resistance.
In the present invention, a complex is a copolymer having two or more polymer segments obtained by polymerizing monomers divided into a plurality of series, and two or more types obtained by polymerizing monomers divided into a plurality of series. It means a mixture of polymers.

<Characteristics of stereocomplex polylactic acid resin composition>
The stereocomplex polylactic acid resin composition of the present invention in which the stereocomplex formation rate and optical purity are within the above ranges can be obtained by crystal melting by using a small amount of D-form lactide (while using a large amount of L-form lactide). The peak temperature is high, the half width is narrow, and the heat resistance is excellent.

  In the present invention, the stereocomplex formation rate, optical purity, crystal melting peak temperature, and half-value width are determined as follows.

[Stereo complex formation rate]
The stereocomplex formation rate is the homopolylactic acid crystal on the low temperature side and the stereocomplex polylactic acid crystal on the high temperature side when the crystallization peak obtained by DSC measurement (differential scanning calorimetry) is two peaks, (ΔHmc, homo) obtained from the homo crystallization peak of (1) and (ΔHmc, stereo) obtained from the stereocomplex crystallization peak at the time of temperature increase.
Stereo complex formation rate (%) = {(ΔHmc, stereo) / ((ΔHmc, homo) + (ΔHmc, stereo))} × 100

  Here, when obtaining the stereo complex formation rate, a method for obtaining the peak will be specifically described with reference to FIG. FIG. 7 is a diagram showing an example of DSC measurement results, in which the vertical axis represents heat (Heat Flow (W / g)), the horizontal axis represents temperature (Temperature (° C.)), the right side is the high temperature side, and the left side is Represents the low temperature side. A peak is judged based on a change point (indicated by an arrow in the figure) of 0.025 (W / g) / 3 (° C.) or more.

[Optical purity]
The optical purity is determined from the constituent ratios of poly-L-lactic acid, L-form lactic acid and D-form lactic acid constituting poly-D-lactic acid.
To 1 g of sample, 5 mL of 5M sodium hydroxide and 2.5 mL of isopropanol are added, and the mixture is hydrolyzed with heating and stirring at 40 ° C., and then neutralized with 1M sulfuric acid. The concentration is adjusted by diluting 1 mL of the neutralized solution 25 times. This was subjected to HPLC to measure the detection peak area of L-form lactic acid and D-form lactic acid at UV light UV254 nm, and the weight ratio [L] of L-form lactic acid constituting the stereocomplex polylactic acid resin composition. The optical purity (%) is calculated by the following formula from (%) and the weight ratio [D] (%) of D-form lactic acid. In addition, as an HPLC apparatus, a pump: Shimadzu LC-6A, a UV detector: Shimadzu SPD-6AV, a column: SUMICHIRAL OA-5000 (Sumitomo Chemical Analysis Center Co., Ltd.) was used, and a 1 mM copper sulfate aqueous solution was used as an eluent. Used, measured at a flow rate of 1.0 mL / min and 40 ° C.
Optical purity (%) = 100 × [L] / ([L] + [D])
Or 100 × [D] / ([L] + [D])

[Crystal melting peak temperature]
The crystal melting peak temperature indicates the maximum value of the crystal melting peak in the DSC curve obtained in the differential scanning calorimetry. However, when there is a crystal melting peak with a crystal melting enthalpy of 2 J / g or less, it is considered that there is no crystal melting peak.
The crystal melting peak between 160 ° C. and 170 ° C. occurs when (A) poly-L-lactic acid or (B) poly-D-lactic acid is crystallized independently.

[Half width]
A method for obtaining the half-value width will be specifically described with reference to FIG. FIG. 8 is a diagram showing an example of DSC measurement results, where the vertical axis represents heat (Heat Flow (W / g)), the horizontal axis represents temperature (Temperature (° C.), the right side is the high temperature side, and the left side is the low temperature. Represents the side.
The full width at half maximum is a line parallel to the vertical axis of the graph drawn from the apex (point a) of the crystal melting peak of the DSC curve obtained in the differential scanning calorimetry, and the intersection (point b) of the straight line and the baseline of the DSC curve. ), The width of the peak at the midpoint (point c) of the line segment connecting (point a) and (point b). The peak width referred to here is a width on a straight line parallel to the base line and passing through (point c).

The stereocomplex polylactic acid resin composition of the present invention also exhibits the following properties by being produced by the production method of the present embodiment described later.
According to the manufacturing method of the present embodiment described later, since a polymerization reaction at a low temperature is possible by using a compressive fluid, the depolymerization reaction can be significantly suppressed as compared with the conventional melt polymerization. Thereby, the polymer conversion rate can be 96 mol% or more, preferably 98 mol% or more. When the polymer conversion rate is less than 96 mol%, the thermal characteristics as the polymer product may be insufficient, and an operation for removing the ring-opening polymerizable monomer may be required separately. In the present embodiment, the polymer conversion rate means the ratio of the ring-opening polymerizable monomer that has contributed to the formation of the polymer with respect to the ring-opening polymerizable monomer as a raw material. The amount of the ring-opening polymerizable monomer that has contributed to the production of the polymer is obtained by subtracting the amount of the unreacted ring-opening polymerizable monomer from the amount of the polymer that has been produced.

  The number average molecular weight of the stereocomplex polylactic acid resin composition obtained by this embodiment can be adjusted by the amount of the initiator. Although not particularly limited, the number average molecular weight is generally from 12,000 to 200,000. When the number average molecular weight is larger than 200,000, it may not be economical due to a deterioration in productivity accompanying an increase in viscosity. When the number average molecular weight is less than 12,000, the strength as a polymer may be insufficient, which may not be preferable. In the present embodiment, the number average molecular weight is preferably 100,000 or more.

  The value obtained by dividing the weight average molecular weight of the stereocomplex polylactic acid resin composition obtained by the present embodiment by the number average molecular weight is preferably in the range of 1.0 to 2.5, and in the range of 1.0 to 2.0. Is more preferable. When this value is larger than 2.0, there is a high possibility that the polymerization reaction is performed non-uniformly, and it is difficult to control the physical properties of the polymer.

Since the stereocomplex polylactic acid resin composition obtained according to the present embodiment is produced by a production method that does not use an organic solvent, the organic solvent substantially does not contain an organic solvent and exists in the stereocomplex polylactic acid resin composition. The amount is 1 ppm or less, and the amount of remaining monomer (lactide) is also extremely small, 1,000 ppm or less. Moreover, the stereocomplex polylactic acid resin composition with few metal atom content can also be obtained by using an organic catalyst as a catalyst and suppressing the usage-amount of a metal catalyst. In this case, the amount of the metal catalyst present in the stereocomplex polylactic acid resin composition can be 5 ppm or less. A stereocomplex polylactic acid resin composition that satisfies these conditions is excellent in safety and stability. Moreover, in this embodiment, as a result of making the said reaction at low temperature for a short time, it is a stereocomplex polylactic acid resin composition without coloring, and is excellent in practicality. The stereocomplex polylactic acid resin composition obtained by the present embodiment has a YI value indicating the degree of coloration of 10 or less.
In the present invention, “substantially free of metal catalyst” means that the content of the metal catalyst in the polymer product is detected by a known analysis method such as ICP emission spectrometry, atomic absorption spectrometry or colorimetry. Means that it is below the detection limit. The organic solvent refers to an organic solvent used for ring-opening polymerization, and substantially does not contain an organic solvent. The content of the organic solvent in the polymer product measured by the following measurement method is the detection limit. It means the following.

  In the present invention, the molecular weight, monomer (lactide) amount, YI value, organic solvent amount, and metal catalyst amount of the polymer product (stereocomplex polylactic acid resin composition) are determined as follows.

[Molecular weight measurement of polymer products]
Measurement is performed under the following conditions by GPC (Gel Permeation Chromatography).
-Equipment: GPC-8020 (manufactured by Tosoh Corporation)
Column: TSK G2000HXL and G4000HXL (manufactured by Tosoh Corporation)
・ Temperature: 40 ℃
・ Solvent: Chloroform ・ Flow rate: 1.0 mL / min 1 mL of a polymer product having a concentration of 0.5 mass% was injected, and a molecular weight calibration prepared with a monodisperse polystyrene standard sample from the molecular weight distribution of the polymer product measured under the above conditions. The number average molecular weight Mn and the weight average molecular weight Mw of the polymer are calculated using the curve. The molecular weight distribution is a value obtained by dividing Mw by Mn.

[Amount of lactide]
Residual monomer amount (lactide amount) of polymer product (polylactic acid) is “Voluntary Standard for Food Containers and Packaging Made of Synthetic Resins such as Polyolefins, Third Edition Revised Edition, June 2004 Supplement, Part 3, Hygiene Test Method , P13 "can be determined according to the lactide content measuring method.
Specifically, a polymer product such as polylactic acid is uniformly dissolved in dichloromethane, and the supernatant obtained by reprecipitation of the polymer product by adding an acetone / cyclohexane mixed solution is gas chromatograph with a hydrogen flame detector (FID). The residual monomer amount in the polymer product can be measured by subjecting it to (GC) and separating the residual monomer (lactide) and quantifying it by an internal standard method. The GC measurement can be performed under the following conditions.

-GC measurement conditions-
Column: Capillary column DB-17MS manufactured by J & W (length 30 m × inner diameter 0.25 mm, film thickness 0.25 μm)
Internal standard: 2,6-dimethyl-γ-pyrone Column flow rate: 1.8 mL / min Column temperature: 50 ° C. hold for 1 minute. The temperature is raised at a constant rate of 25 ° C./min and maintained at 320 ° C. for 5 minutes.
Detector: Hydrogen flame ionization method (FID)

[Measurement of YI (Yellow Index) Value]
In order to investigate the yellowness and yellowing degree of the polymer product, resin pellets having a thickness of 2 mm are prepared and measured according to JIS standard K7103 using an SM color computer (manufactured by Suga Test Instruments Co., Ltd.) to determine the YI value.

[Amount of organic solvent]
After adding 2 parts by mass of 2-propanol to 1 part by mass of the polymer product to be measured and dispersing with ultrasonic waves for 30 minutes, it is stored in a refrigerator (5 ° C.) for 1 day or longer, and the organic solvent in the polymer product To extract. The supernatant is analyzed by gas chromatography (GC-14A, SHIMADZU), and the organic solvent concentration is measured by quantifying the organic solvent and residual monomers in the polymer product. Measurement conditions at the time of such analysis are as follows.
Equipment: Shimadzu GC-14A
Column: CBP20-M 50-0.25
Detector: FID
Injection volume: 1 μL to 5 μL
Carrier gas: He 2.5 kg / cm ²
Hydrogen flow rate: 0.6 kg / cm ²
Air flow rate: 0.5 kg / cm ²
Chart speed: 5mm / min
Sensitivity: Range101 × Atten20
Column temperature: 40 ° C
Injection Temp: 150 ° C
Detection lower limit: 5 ppm

[Amount of metal catalyst]
ICP emission spectrometry (high frequency inductively coupled plasma emission spectroscopy) is measured under the following conditions, and the amount of metal catalyst is determined based on the measurement results.
・ Device: ICP emission spectroscopic analyzer (ICP-OES / ICP-AES)
SPS5100, manufactured by SII NanoTechnology Lower detection limit: 5ppm
A sample (polymer product) is decomposed by heating to 230 ° C. with sulfuric acid and nitric acid, and then the volume is adjusted with ultrapure water to obtain a test solution. Quantitative analysis of the metal in the test solution (Sn in Example 7 described later) is performed by ICP-AES method.

<Method for producing stereocomplex polylactic acid resin composition>
The method for producing the stereocomplex polylactic acid resin composition includes at least the L-lactide or D-lactide ring-opening polymerization step for obtaining the poly-L-lactic acid or the poly-D-lactic acid, the poly-L-lactic acid, A mixing step for obtaining a mixture with poly-D-lactic acid, and other steps as necessary.

In the method for producing the stereocomplex polylactic acid resin composition, in addition to the compressive fluid used in the ring-opening polymerization step, the compressive fluid is added in the mixing step and mixed in a state where the concentration of the compressive fluid is increased. It is good to do.
The present inventors polymerized each raw material of L-form lactide and D-form lactide in a compressive fluid, and then obtained poly-L-lactic acid and poly-D-lactic acid obtained in the process. When mixing and mixing under the condition that the compressive fluid was added and the concentration of the compressive fluid was increased, even when a small amount of D-form lactide was used, the stereocomplex formation rate and optical purity were within a specific range. A stereocomplex polylactic acid resin composition showing a value is obtained, and this stereocomplex polylactic acid resin composition is a stereocomplex polylactic acid resin composition having a high crystal melting peak temperature, a narrow half-value width, and excellent heat resistance. I found out.
The reason is not clear, but by increasing the compressive fluid concentration, the mixed state of poly-L-lactic acid and poly-D-lactic acid changes, which efficiently converts the input D-form lactide into a stereocomplex. I guess that it works particularly well.

More specifically, the stereocomplex polylactic acid resin composition is produced by bringing a raw material containing an L-form lactide into contact with a compressive fluid to cause ring-opening polymerization of the L-form lactide. An L-form lactide ring-opening polymerization step to obtain poly-L-lactic acid;
The D-form lactide that has been brought into contact with the compressive fluid is brought into contact with the poly-L-lactic acid that is still in contact with the compressive fluid, and the D-form lactide is opened under the condition that the compressive fluid is further added. A production method (A) including a mixing step of obtaining a mixture of poly-L-lactic acid and poly-D-lactic acid by ring polymerization is exemplified.
Further, as another method for producing the stereocomplex polylactic acid resin composition, a raw material containing an L-form lactide is brought into contact with a compressive fluid to cause ring-opening polymerization of the L-form lactide. -L-lactide ring-opening polymerization step to obtain -L-lactic acid;
A D-form lactide ring-opening polymerization step of obtaining poly-D-lactic acid by bringing a D-form lactide-containing raw material into contact with a compressive fluid and ring-opening polymerization of the D-form lactide;
The poly-L-lactic acid and the poly-D-lactic acid remaining in contact with the compressive fluid are brought into contact with and mixed with the poly-L-lactic acid and the poly-D-lactic acid in a state in which a compressive fluid is further added. And a production method (B) including a mixing step of obtaining a mixture with poly-D-lactic acid.

<< Ring-opening polymerization process >>
The L-form lactide ring-opening polymerization step is a step of bringing the L-form lactide into ring-opening polymerization by bringing a raw material containing the L-form lactide into contact with a compressive fluid.
The D-form lactide ring-opening polymerization step is a step of bringing the D-form lactide into ring-opening polymerization by bringing a raw material containing the D-form lactide into contact with a compressive fluid.
In the L-form lactide and D-form lactide ring-opening polymerization step, the L-form or D-form lactide may be subjected to ring-opening polymerization using a catalyst.

<<< Raw materials >>>
In the present invention, the raw material refers to a material from which a polymer is produced and is a material constituting a polymer component. The raw material includes the L-form or D-form lactide which is a ring-opening polymerizable monomer. In addition, it contains a polymerization initiator and additives as necessary.

-Ring-opening polymerizable monomer-
The ring-opening polymerizable monomer is not particularly limited as long as it can be polymerized to obtain poly-L-lactic acid or poly-D-lactic acid, and can be appropriately selected according to the purpose. Of lactide or D-form lactide.

-Polymerization initiator-
The raw material may contain a polymerization initiator (hereinafter also referred to as “initiator”) as necessary. The polymerization initiator is not particularly limited as long as it is an initiator that gives a branched structure to the polymer product, and can be appropriately selected according to the purpose. For example, any of monoalcohol, dialcohol, and polyhydric alcohol can be used. It may be either saturated alcohol or unsaturated alcohol.

Examples of the monoalcohol include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, nonanol, decanol, lauryl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol.
Examples of the dialcohol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexanediol, nonanediol, tetramethylene glycol, and polyethylene glycol. Etc.
Examples of the polyhydric alcohol include glycerol, sorbitol, xylitol, ribitol, erythritol, triethanolamine, and the like.
Examples of the unsaturated alcohol include methyl lactate and ethyl lactate.

  Further, a polymer having an alcohol residue at the terminal, such as polycaprolactone diol or polytetramethylene glycol, may be used as the polymerization initiator. Thereby, a diblock or triblock copolymer is synthesized.

  There is no restriction | limiting in particular as the usage-amount of the said polymerization initiator, Although it can select suitably according to the objective, 0.05 mol% or more and 5 mol% or less are preferable with respect to the said ring-opening polymerizable monomer. In order to prevent the polymerization from starting unevenly, it is desirable that the initiator is well mixed with the monomer in advance before the monomer contacts the polymerization catalyst.

-Additives-
You may make the said raw material contain an additive as needed. Examples of the additive include surfactants, antioxidants, stabilizers, antifogging agents, ultraviolet absorbers, pigments, colorants, inorganic particles, various fillers, thermal stabilizers, flame retardants, crystal nucleating agents, and charging agents. Inhibitors, surface wetting improvers, incineration aids, lubricants, natural products, mold release agents, plasticizers, and the like.
There is no restriction | limiting in particular as the usage-amount of the said additive, Although it can select suitably according to the objective and the kind of additive, 0 to 5 mass parts is preferable with respect to 100 mass parts of polymer compositions. .

  As the surfactant, those that melt into the compressive fluid and have affinity for both the compressive fluid and the ring-opening polymerizable monomer are preferably used. By using such a surfactant, the polymerization reaction can be progressed uniformly, and a product having a narrow molecular weight distribution can be obtained, and effects such as easy to obtain a particulate polymer can be expected. When using a surfactant, it may be added to the compressive fluid or to the ring-opening polymerizable monomer. For example, when carbon dioxide is used as the compressive fluid, a surfactant having a parent carbon dioxide group and a parent monomer group in the molecule is used. Examples of such surfactants include fluorine-based surfactants and silicon-based surfactants.

Examples of the stabilizer include epoxidized soybean oil and carbodiimide.
Examples of the antioxidant include 2,6-di-t-butyl-4-methylphenol and butylhydroxyanisole.
Examples of the antifogging agent include glycerin fatty acid ester and monostearyl citrate.
Examples of the filler include an ultraviolet absorber, a heat stabilizer, a flame retardant, an internal mold release agent, and a crystal nucleating agent. Specific examples include clay, talc, and silica.
Examples of the pigment include titanium oxide, carbon black, and ultramarine blue.

<<< Compressible fluid >>>
The compressive fluid will be described with reference to FIGS. 1 and 2. FIG. 1 is a phase diagram showing the state of a substance with respect to temperature and pressure. FIG. 2 is a phase diagram for defining the range of the compressible fluid in the present embodiment.
The compressible fluid means a fluid in a state existing in one of the regions (1), (2), and (3) shown in FIG. 2 in the phase diagram shown in FIG. .

  In such a region, it is known that the substance has a very high density and behaves differently from that at normal temperature and pressure. In addition, when a substance exists in the area | region of (1), it becomes a supercritical fluid. A supercritical fluid is a fluid that exists as a non-condensable high-density fluid in a temperature and pressure region that exceeds the limit (critical point) at which gas and liquid can coexist, and does not condense even when compressed. Further, when the substance is present in the region (2), it becomes a liquid, but in this embodiment, it is obtained by compressing a substance that is in a gaseous state at normal temperature (25 ° C.) and normal pressure (1 atm). Represents liquefied gas. Further, when the substance is present in the region (3), it is in a gaseous state, but in the present embodiment, it represents a high pressure gas whose pressure is 1/2 (1/2 Pc) or more of the critical pressure (Pc).

  Examples of the substance constituting the compressive fluid include carbon monoxide, carbon dioxide, dinitrogen monoxide, nitrogen, methane, ethane, propane, 2,3-dimethylbutane, and ethylene. Among these, carbon dioxide is preferable in that it has a critical pressure of about 7.4 MPa and a critical temperature of about 31 ° C., can easily create a supercritical state, and is nonflammable and easy to handle. These compressive fluids may be used alone or in combination of two or more.

  Since carbon dioxide reacts with substances having basicity and nucleophilicity, conventionally, when supercritical carbon dioxide is used as a solvent, it has been said that it cannot be applied to living anion polymerization. However, the present inventors overturned the conventional knowledge, and even in supercritical carbon dioxide, the organic catalyst having basicity and nucleophilicity is stably coordinated to the ring-opening monomer, and the ring-opening monomer is allowed to open the ring. The inventors have found that the polymerization reaction proceeds quantitatively in a short time, and as a result, the polymerization reaction proceeds in a living manner. Living as used herein means that the reaction proceeds quantitatively without side reactions such as transfer reaction and termination reaction, and the molecular weight distribution of the obtained polymer is relatively narrow and monodisperse.

<<< Catalyst >>>
There is no restriction | limiting in particular as said catalyst, According to the objective, it can select suitably, For example, the organic catalyst which does not contain a metal atom, the metal catalyst containing a metal atom, etc. are mentioned.

-Organic catalyst containing no metal atoms-
The organic catalyst containing no metal atom (hereinafter also referred to as “organic catalyst”) is not particularly limited and may be appropriately selected depending on the purpose. For example, the ring-opening polymerizability does not contain a metal atom. What contributes to the ring-opening polymerization reaction of the monomer, forms an active intermediate with the ring-opening polymerizable monomer, and then desorbs and regenerates by reaction with alcohol is preferable.

  The organic catalyst is preferably a (nucleophilic) compound that functions as a basic nucleophile, more preferably a compound containing a nitrogen atom, and particularly preferably a cyclic compound containing a nitrogen atom. The nitrogen atom-containing compound is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a cyclic monoamine, a cyclic diamine (for example, a cyclic diamine compound having an amidine skeleton), and a guanidine skeleton. Examples thereof include a cyclic triamine compound, a heterocyclic aromatic organic compound containing a nitrogen atom, and N-heterocyclic carbene. A cationic organic catalyst is used for ring-opening polymerization. In this case, since hydrogen is extracted from the polymer main chain (back-biting), the molecular weight distribution becomes wide and it is difficult to obtain a high molecular weight product.

Examples of the cyclic monoamine include quinuclidine.
Examples of the cyclic diamine include 1,4-diazabicyclo- [2.2.2] octane (DABCO), 1,5-diazabicyclo (4,3,0) -5-nonene.
Examples of the cyclic diamine compound having an amidine skeleton include 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) and diazabicyclononene.
Examples of the cyclic triamine compound having a guanidine skeleton include 1,5,7-triazabicyclo [4.4.0] dec-5-ene (TBD) and diphenylguanidine (DPG).
Examples of the heterocyclic aromatic organic compound containing a nitrogen atom include N, N-dimethyl-4-aminopyridine (DMAP), 4-pyrrolidinopyridine (PPY), pyrocholine, imidazole, pyrimidine, and purine. Can be mentioned.
Examples of the N-heterocyclic carbene include 1,3-di-tert-butylimidazol-2-ylidene (ITBU).
Among these, the DABCO, the DBU, the DPG, the TBD, the DMAP, the PPY, and the ITBU are used because they have a low steric hindrance and high nucleophilicity or have a boiling point that can be removed under reduced pressure. preferable.

  Among these organic catalysts, for example, DBU is liquid at room temperature and has a boiling point. When such an organic catalyst is selected, the organic catalyst can be almost quantitatively removed from the polymer product by subjecting the obtained polymer product to a reduced pressure treatment. In addition, the kind of organic catalyst and the presence or absence of a removal process are determined according to the use purpose of a product, etc.

The type and amount of the organic catalyst vary depending on the combination of the compressive fluid and the ring-opening polymerizable monomer, and thus cannot be specified unconditionally. The mol% or less is preferable, 0.1 mol% or more and 1 mol% or less is more preferable, and 0.3 mol% or more and 0.5 mol% or less is particularly preferable.
When the amount used is less than 0.01 mol%, the organic catalyst may be deactivated before the polymerization reaction is completed, and a polymer having a target molecular weight may not be obtained. On the other hand, when the amount used exceeds 15 mol%, it may be difficult to control the polymerization reaction.

  The catalyst used in the present invention is preferably the organic catalyst from the viewpoints of product safety and stability. Further, when the organic catalyst is used in the production method of the present invention, the polymer conversion rate is compared with the case where the ring-opening polymerizable monomer is subjected to ring-opening polymerization using the organic catalyst in the conventional production method. The time required for the polymerization reaction can be shortened.

-Catalysts containing metal atoms-
The catalyst containing the metal atom (hereinafter also referred to as “metal catalyst”) is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a tin compound, an aluminum compound, a titanium compound, Zirconium compounds, antimony compounds, and the like can be given.
Examples of the tin compound include tin octylate, tin dibutyrate, and di (2-ethylhexanoic acid) tin.
Examples of the aluminum compound include aluminum acetylacetonate and aluminum acetate.
Examples of the titanium compound include tetraisopropyl titanate and tetrabutyl titanate.
Examples of the zirconium-based compound include zirconium isoprooxide.
Examples of the antimony compound include antimony trioxide.

  The type and amount of the metal catalyst cannot be specified because it varies depending on the combination of the compressive fluid and the ring-opening polymerizable monomer, but in terms of colorability and conversion rate, 200 ppm or more and 5,000 ppm or less is preferable, and 500 ppm or more and 1,000 or less is more preferable.

<<< Polymerization reactor >>>
Subsequently, an example of a polymerization reaction apparatus used in the ring-opening polymerization step (hereinafter also referred to as “polymerization step”) in the method for producing the stereocomplex polylactic acid resin composition of the present invention will be described with reference to FIGS. To do. 3 to 4 are system diagrams showing an example of the polymerization step.

  First, the polymerization reaction apparatus 100 shown in FIG. 3 will be described. In the system diagram of FIG. 3, the polymerization reaction apparatus 100 includes a supply unit 100 a that supplies a raw material such as a ring-opening polymerizable monomer and a compressive fluid, and a continuous polymerization that polymerizes the ring-opening polymerizable monomer supplied by the supply unit 100 a. And a polymerization reaction apparatus main body 100b as an example of the apparatus. The supply unit 100a has a tank (1, 3, 5, 7, 11), a measuring feeder (2, 4), and a measuring pump (6, 8, 12). The polymerization reaction device main body 100b includes a melt mixing device 9, a liquid feed pump 10, a reaction vessel 13, a metering pump 14, and the other end of the polymerization reaction device main body 100b provided at one end of the polymerization reaction device main body 100b. And an extrusion die 15 provided on the surface. In the present invention, “melting” means a state in which a raw material or a produced polymer comes into contact with a compressive fluid and is plasticized or liquefied while swelling. In addition, the “melt mixing device” is a device that melts raw materials by bringing the compressive fluid into contact with the raw materials.

  The tank 1 of the supply unit 100a stores a ring-opening polymerizable monomer. The ring-opening polymerizable monomer to be stored may be a powder or a molten state. The tank 3 stores a solid (powder or granular) one of the initiator and the additive. The tank 5 stores a liquid one of the initiator and the additive. The tank 7 stores a compressible fluid. In addition, the tank 7 may store a gas (gas) or a solid that becomes a compressible fluid in a process of being supplied to the melt mixing device 9 or heated or pressurized in the melt mixing device 9. . In this case, the gas or solid stored in the tank 7 is heated or pressurized, and the state of (1), (2), or (3) in the phase diagram of FIG. Become.

  The metering feeder 2 measures the ring-opening polymerizable monomer stored in the tank 1 and continuously supplies it to the melt mixing device 9. The weighing feeder 4 measures the solid stored in the tank 3 and continuously supplies it to the melt mixing device 9. The metering pump 6 measures the liquid stored in the tank 5 and continuously supplies it to the melt mixing device 9. The metering pump 8 continuously supplies the compressive fluid stored in the tank 7 to the melt mixing device 9 at a constant pressure and flow rate. In addition, in this embodiment, supplying continuously is a concept with respect to the method of supplying for every batch, and means supplying so that the polymer which carried out ring-opening polymerization may be obtained continuously. In other words, each material may be supplied intermittently or intermittently as long as the ring-opened polymer is continuously obtained. In addition, when both the initiator and the additive are solid, the polymerization reaction apparatus 100 may not include the tank 5 and the metering pump 6. Similarly, when both the initiator and the additive are liquid, the polymerization reaction apparatus 100 may not include the tank 3 and the metering feeder 4.

  In this embodiment, each apparatus of the polymerization reaction apparatus main body 100b is connected as shown in FIG. 3 by a pressure-resistant piping 30 that transports raw materials, a compressive fluid, or a generated polymer. In addition, each of the melt mixing device 9, the liquid feeding pump 10, and the reaction vessel 13 of the polymerization reaction device has a tubular member through which the above raw materials and the like pass.

  The melt mixing device 9 of the polymerization reaction device main body 100b includes raw materials such as ring-opening polymerizable monomers, initiators and additives supplied from the tanks (1, 3, 5), and a compressive fluid supplied from the tank 7. Is a device having a pressure-resistant container for melting the raw materials. In this embodiment, since the raw material such as the ring-opening polymerizable monomer and the compressive fluid can be continuously contacted at a constant concentration ratio, the raw material can be efficiently melted into the compressive fluid. it can.

  The shape of the container of the melt mixing device 9 may be a tank type or a cylindrical type, but a cylindrical type in which raw materials are supplied from one end and the mixture is taken out from the other end is preferable. In the container of the melt mixing device 9, an inlet 9 a for introducing the compressive fluid supplied from the tank 7 by the metering pump 8 and an inlet for introducing the ring-opening polymerizable monomer supplied from the tank 1 by the metering feeder 2 are introduced. 9b, an inlet 9c for introducing the powder supplied from the tank 3 by the measuring feeder 4, and an inlet 9d for introducing the liquid supplied from the tank 5 by the measuring pump 6 are provided. In this embodiment, each inlet (9a, 9b, 9c, 9d) is comprised by the coupling which connects the container of the melt mixing apparatus 9, and each piping which conveys each raw material or compressive fluid. This joint is not particularly limited, and known joints such as reducers, couplings, Y-type joints, T-type joints, and outlets are used. Moreover, the melt mixing apparatus 9 has a heater for heating each supplied raw material and compressive fluid. Furthermore, the melt mixing device 9 may have a stirring device for stirring raw materials, compressive fluids, and the like. When the melt mixing device 9 has a stirrer, the stirrer includes a uniaxial screw, a biaxial screw that meshes with each other, a biaxial mixer that has a large number of meshing elements that mesh with or overlap each other, and a helical stirring element that meshes with each other. A kneader, a static mixer or the like having the above is preferably used. In particular, a biaxial or multiaxial agitation device that meshes with each other is preferable because there is little adhesion of reactants to the agitation device or the container and there is a self-cleaning action. In the case where the melt mixing device 9 does not have a stirrer, a pressure resistant pipe is preferably used as the melt mixing device 9. In addition, when the melt mixing apparatus 9 does not have a stirring apparatus, in order to mix each material in the melt mixing apparatus 9 reliably, the ring-opening polymerizable monomer supplied to the melt mixing apparatus 9 is in a molten state. It is preferable.

  The liquid feed pump 10 feeds each raw material melted by the melt mixing device 9 to the reaction vessel 13. The tank 11 stores a catalyst. The metering pump 12 measures the catalyst stored in the tank 11 and supplies it to the reaction vessel 13.

  The reaction container 13 is a pressure-resistant container for mixing the melted raw materials fed by the liquid feed pump 10 and the catalyst supplied by the metering pump 12 to cause the ring-opening polymerizable monomer to undergo ring-opening polymerization. It is. The shape of the reaction vessel 13 may be a tank type or a cylindrical type, but a cylindrical type with little dead space is preferable.

The reaction vessel 13 has an introduction port 13a for introducing each material mixed by the melt mixing device 9 into the vessel, and an introduction port 13b for introducing the catalyst supplied from the tank 11 by the metering pump 12 into the vessel. Is provided. In this embodiment, each inlet (13a, 13b) is comprised by the coupling which connects the reaction container 13 and each piping which conveys each raw material. This joint is not particularly limited, and known joints such as reducers, couplings, Y-type joints, T-type joints, and outlets are used. The reaction vessel 13 may be provided with a gas outlet for removing the evaporated material. The reaction vessel 13 has a heater for heating the fed raw material.
Furthermore, the reaction vessel 13 may have a stirring device that stirs the raw materials, the compressive fluid, and the like. When the reaction vessel 13 has a stirrer, the polymer particles can be prevented from settling due to the difference in density between the raw material and the produced polymer, so that the polymerization reaction can proceed more uniformly and quantitatively. As a stirring device for the reaction vessel 13, a twin shaft having a screw which meshes with each other, a stirring element such as a 2-flight (oval) or a 3-flight (triangular shape), a disc or a multi-leaf type (clover-shaped) stirring blade. Or the thing of a multi-axis is preferable from a viewpoint of self-cleaning. In the case where the raw material containing the catalyst is sufficiently mixed in advance, a static mixer that performs multi-stage division and combination (merging) of the flow with a guide device can also be applied to the stirring device. As static mixers, those disclosed in JP-B-47-15526, 47-15527, 47-15528, 47-15533, etc. (multilayer mixer), and disclosed in JP-A-47-33166. And the like (Kenix type) and similar mixing devices without moving parts. When the reaction vessel 13 does not have a stirrer, pressure-resistant piping is preferably used as the reaction vessel 13.

  Although FIG. 3 shows an example in which one reaction vessel 13 is provided, two or more reaction vessels 13 may be used. When a plurality of reaction vessels 13 are used, the reaction (polymerization) conditions for each reaction vessel 13, that is, temperature, catalyst concentration, pressure, average residence time, stirring speed, etc. may be the same. It is preferable to select the optimum conditions. In order to increase the reaction time and complicate the apparatus, it is not a good idea to combine too many containers in multiple stages, and the number of stages is preferably 1 or more and 4 or less, particularly preferably 1 or more and 3 or less.

  In general, when polymerization is performed with only one reaction vessel, the degree of polymerization of the polymer obtained and the amount of residual monomer are unstable and easily fluctuate, and are not suitable for industrial production. This is considered to be caused by instability due to mixing of a polymerization raw material having a melt viscosity of several poise to several tens of poise and a polymerized polymer having a melt viscosity of about 1,000 poise in the same container. . On the other hand, in this embodiment, since the raw material and the produced polymer are melted (liquefied), it becomes possible to reduce the difference in viscosity in the reaction vessel 13 (also referred to as a polymerization system), so that the conventional polymerization Even if the number of stages is reduced as compared with the reactor, the polymer can be produced stably.

  The metering pump 14 sends the polymer product P polymerized in the reaction vessel 13 out of the reaction vessel 13 from an extrusion die 15 as an example of a polymer discharge port. In addition, the polymer product P can be sent out from the reaction vessel 13 without using the metering pump 14 by utilizing the pressure difference between the inside and outside of the reaction vessel 13. In this case, in order to adjust the pressure in the reaction vessel 13 and the delivery amount of the polymer product P, the pressure adjusting valve 16 can be used as shown in FIG.

<<< continuous polymerization method >>>
The continuous polymerization method of the ring-opening polymerizable monomer in the present embodiment will be specifically described using the polymerization reaction apparatus 100.
In the polymerization reaction apparatus 100, the raw material containing the L-form or D-form lactide, which is the ring-opening polymerizable monomer, and the compressive fluid are continuously brought into contact with each other, and the L-form or D-form lactide is contacted. Is subjected to ring-opening polymerization to continuously obtain poly-L-lactic acid and poly-D-lactic acid.

  First, each metering feeder (2, 4), the metering pump 6, and the metering pump 8 are operated, and the ring-opening polymerizable monomer, initiator, additive, compressive fluid in each tank (1, 3, 5, 7). Are continuously introduced into the container of the melt mixing device 9 from each inlet (9a, 9b, 9c, 9d). In addition, solid (powder or granular) raw materials may have lower measurement accuracy than liquid raw materials. In this case, the solid raw material may be previously melted and stored in the tank 5 in a liquid state, and introduced into the container of the melt mixing device 9 by the metering pump 6. The order in which each metering feeder (2, 4), metering pump 6 and metering pump 8 are operated is not particularly limited, but when the initial raw material is sent to the reaction vessel 13 without contacting the compressed fluid, it solidifies due to a decrease in temperature. Therefore, it is preferable to operate the metering pump 8 first.

  Each feed rate of each raw material by the metering feeders (2, 4) and the metering pump 6 is adjusted to be a constant ratio based on a predetermined ratio of the ring-opening polymerizable monomer, the initiator, and the additive. The The total mass (raw material feed rate, (g / min)) of each raw material supplied per unit time by the measuring feeder (2, 4) and the measuring pump 6 is adjusted based on the desired polymer physical properties, reaction time, etc. Is done. Similarly, the supply speed of compressible fluid by the metering pump 8 (compressive fluid feed amount, (g / min)) is adjusted based on desired polymer physical properties, reaction time, and the like.

The ratio of the compressible fluid feed amount to the raw material feed amount (raw material feed amount / compressible fluid feed amount, feed ratio) is preferably 1 or more, more preferably 3 or more, and 5 or more. More preferably, it is particularly preferably 10 or more.
Further, the upper limit of the feed ratio is preferably 1,000 or less, more preferably 100 or less, and particularly preferably 50 or less.

By setting the above feed ratio to 1 or more, when each raw material and compressive fluid are sent to the reaction vessel 13, the reaction proceeds in a state where the concentration of the raw material and the generated polymer (so-called solid content concentration) is high. To do. The solid content concentration in the polymerization system at this time is the solid content concentration of the polymerization system when polymerizing by dissolving a small amount of ring-opening polymerizable monomer in an overwhelming amount of compressive fluid in the conventional production method. Are very different. The production method of this embodiment is characterized in that the polymerization reaction proceeds efficiently and stably even in a polymerization system having a high solid content concentration.
In this embodiment, the feed ratio may be less than 1. Even in this case, there is no problem in the quality of the polymer product to be obtained, but the economical efficiency is inferior. On the other hand, if the feed ratio exceeds 1,000, the ability of the compressive fluid to melt the ring-opening polymerizable monomer may be insufficient, and the intended reaction may not proceed uniformly.

  Since each raw material and compressive fluid are continuously introduced into the container of the melt mixing device 9, they are in continuous contact with each other. As a result, the raw materials such as the ring-opening polymerizable monomer, the initiator, and the additive are melted in the melt mixing device 9. When the melt mixing device 9 has a stirring device, the raw materials and the compressive fluid may be stirred. In order to prevent the introduced compressive fluid from turning into a gas, the temperature and pressure in the container of the reaction vessel 13 are controlled to a temperature and pressure at least above the triple point of the compressive fluid. This control is performed by adjusting the output of the heater of the melt mixing device 9 or the supply amount of the compressive fluid. In the present embodiment, the temperature at which the ring-opening polymerizable monomer is melted may be a temperature equal to or lower than the melting point at normal pressure of the ring-opening polymerizable monomer. This is considered to be due to the high pressure in the melt mixing device 9 in the presence of the compressive fluid, and the melting point of the ring-opening polymerizable monomer being lower than the melting point at normal pressure. For this reason, even when the amount of the compressive fluid with respect to the ring-opening polymerizable monomer is small, the ring-opening polymerizable monomer is melted in the melt mixing device 9.

  You may adjust the timing which adds heat and stirring to each raw material and a compressive fluid with the melt mixing apparatus 9 so that each raw material may fuse | melt efficiently. In this case, after bringing each raw material and the compressive fluid into contact, heat or stirring may be applied, or heat or stirring may be applied while bringing each raw material into contact with the compressive fluid. In order to melt more reliably, for example, the ring-opening polymerizable monomer and the compressive fluid may be brought into contact with each other after the ring-opening polymerizable monomer is previously melted by applying heat equal to or higher than the melting point. For example, in the case where the melt mixing device 9 is a biaxial mixing device, the above-described embodiments are arranged in an arrangement of screws, the arrangement of the inlets (9a, 9b, 9c, 9d), the temperature of the heater of the melt mixing device 9 This is realized by setting as appropriate.

  In this embodiment, the additive is supplied to the melt mixing device 9 separately from the ring-opening polymerizable monomer, but the additive may be supplied together with the ring-opening polymerizable monomer. Moreover, you may supply an additive after a polymerization reaction. In this case, after taking out the polymer product obtained from the reaction vessel 13, the additive can be added while melt-kneading.

  Each material melted by the melt mixing device 9 is fed by the feed pump 10 and supplied to the reaction vessel 13 from the inlet 13a. On the other hand, the catalyst in the tank 11 is measured by the metering pump 12 and supplied to the reaction vessel 13 through the introduction port 13b. In this embodiment, the catalyst is added after the raw material is melted in the compressive fluid because the catalyst can act at room temperature.

  Conventionally, in a method for ring-opening polymerization of a ring-opening polymerizable monomer using a compressive fluid, the timing for adding a catalyst has not been studied. In the present embodiment, in the ring-opening polymerization, the catalyst is polymerized in the reaction vessel 13 in a state where the mixture of raw materials such as the ring-opening polymerizable monomer and the initiator is sufficiently melted by the compressive fluid because of its high activity. Added in the system. If the catalyst is added while the mixture is not sufficiently melted, the reaction may proceed non-uniformly.

  Each material fed by the liquid feed pump 10 and the catalyst supplied by the metering pump 12 are sufficiently stirred by the stirring device of the reaction vessel 13 as necessary, and heated to a predetermined temperature by the heater. Thereby, the ring-opening polymerizable monomer undergoes ring-opening polymerization in the presence of the catalyst in the reaction vessel 13 (polymerization step).

  The lower limit of the temperature (polymerization reaction temperature) for ring-opening polymerization of the ring-opening polymerizable monomer is not particularly limited, but is preferably 40 ° C, more preferably 50 ° C, and particularly preferably 60 ° C. When the polymerization reaction temperature is less than 40 ° C., depending on the ring-opening polymerizable monomer species, it takes a long time to melt by the compressive fluid, the melting is insufficient, or the activity of the catalyst is lowered. As a result, the reaction rate tends to decrease during polymerization, and the polymerization reaction may not proceed quantitatively.

  The upper limit of the polymerization reaction temperature is not particularly limited, but is 100 ° C. or 30 ° C. higher than the melting point of the ring-opening polymerizable monomer, whichever is higher. The upper limit of the polymerization reaction temperature is preferably 90 ° C. or the higher melting point of the ring-opening polymerizable monomer, and preferably 80 ° C. or 20 ° C. lower than the melting point of the ring-opening polymerizable monomer. Temperature is more preferred. When the polymerization reaction temperature exceeds 30 ° C. higher than the melting point of the ring-opening polymerizable monomer, the depolymerization reaction, which is the reverse reaction of the ring-opening polymerization, tends to occur in equilibrium, and the polymerization reaction is difficult to proceed quantitatively. When using a ring-opening monomer having a low melting point, such as a ring-opening polymerizable monomer that is liquid at room temperature, the polymerization reaction temperature may be 30 ° C. higher than the melting point in order to increase the activity of the catalyst. Even in this case, the polymerization reaction temperature is preferably 100 ° C. or lower. The polymerization reaction temperature is controlled by a heater provided in the reaction vessel 13 or heating from the outside of the reaction vessel 13. Moreover, when measuring polymerization reaction temperature, you may use the polymer product obtained by polymerization reaction.

  In a conventional method for producing a polymer using supercritical carbon dioxide, since supercritical carbon dioxide has a low polymer dissolving ability, a large amount of supercritical carbon dioxide was used to polymerize the ring-opening polymerizable monomer. According to the polymerization method of the present embodiment, in the method for producing a polymer using a compressive fluid, the ring-opening polymerizable monomer is subjected to ring-opening polymerization at an unprecedented high concentration. In this case, the pressure in the reaction vessel 13 becomes high in the presence of the compressive fluid, and the glass transition temperature (Tg) of the produced polymer is lowered. As a result, the viscosity of the produced polymer is lowered, and the ring-opening polymerization reaction proceeds uniformly even when the concentration of the polymer product is high.

  In the present embodiment, the polymerization reaction time (average residence time in the reaction vessel 13) is set according to the target molecular weight, but is usually preferably within 1 hour, more preferably within 45 minutes, and within 30 minutes. Is particularly preferred. According to the production method of the present embodiment, the polymerization reaction time can be set to 20 minutes or less. This is a short time that is unprecedented in the polymerization of ring-opening polymerizable monomers in a compressible fluid.

  The pressure at the time of polymerization, that is, the pressure of the compressive fluid is such that the compressive fluid supplied from the tank 7 is a liquefied gas ((2) in the phase diagram of FIG. 2) or a high-pressure gas ((3) in the phase diagram of FIG. 2). The pressure that becomes the supercritical fluid ((1) in the phase diagram of FIG. 2) is preferable. By making the compressible fluid into a supercritical fluid state, melting of the ring-opening polymerizable monomer is promoted, and the polymerization reaction can be promoted uniformly and quantitatively. When carbon dioxide is used as the compressible fluid, the pressure is preferably 3.7 MPa or more, more preferably 5 MPa or more, and a critical pressure of 7.4 MPa or more, considering efficiency of the reaction, polymer conversion rate, and the like. Particularly preferred. Moreover, when using a carbon dioxide as a compressive fluid, it is preferable that the temperature is 25 degreeC or more for the same reason.

  The water content in the reaction vessel 13 is preferably 4 mol% or less, more preferably 1 mol% or less, and particularly preferably 0.5 mol% or less with respect to the ring-opening polymerizable monomer. When the amount of water exceeds 4 mol%, the water itself contributes as an initiator, so that it may be difficult to control the molecular weight. In order to control the amount of water in the polymerization reaction system, an operation for removing water contained in the ring-opening polymerizable monomer and other raw materials may be added as a pretreatment as necessary.

  The polymer product P that has finished the ring-opening polymerization reaction in the reaction vessel 13 is sent out of the reaction vessel 13 by the metering pump 14. The rate at which the metering pump 14 delivers the polymer product P is preferably constant in order to obtain a uniform polymerized product by operating at a constant pressure in the polymerization system filled with the compressive fluid. Therefore, the liquid feeding mechanism inside the reaction vessel 13 and the liquid feeding amount of the liquid feeding pump 10 are controlled so that the back pressure of the metering pump 14 is constant. Similarly, the feeding speed of the liquid feeding mechanism, the metering feeders (2, 4), and the metering pumps (6, 8) in the melt mixing device 9 are controlled so that the back pressure of the liquid pump 10 is constant. . The control method may be an ON-OFF type, that is, an intermittent feed type, but a continuous or step method in which the rotational speed of a pump or the like is gradually increased or decreased is often more preferable. In any case, a uniform polymer product can be stably obtained by such control.

  The catalyst remaining in the polymer product obtained by this embodiment is removed as necessary. The removal method is not particularly limited.For example, if it is a compound having a boiling point, it is distilled off under reduced pressure, or a method of removing the catalyst by using a substance that dissolves the catalyst as an entrainer, For example, a method of adsorbing and removing a catalyst by a column may be used. In this case, the method for removing the catalyst may be a batch method in which the polymer product is removed after being taken out from the reaction vessel, or a method in which the polymer product is continuously treated without being taken out. In the case of distilling off under reduced pressure, the reduced pressure condition is set based on the boiling point of the catalyst. For example, the temperature during decompression is 100 ° C. or higher and 120 ° C. or lower, and the catalyst can be removed at a temperature lower than the temperature at which the polymer product is depolymerized. When an organic solvent is used in this extraction operation, a step for removing the organic solvent after extraction of the catalyst may be required. For this reason, it is preferable to use a compressed fluid as a solvent also in extraction operation. As such an extraction operation, a known technique such as extraction of a fragrance can be diverted.

<< Mixing process >>
The mixing step is not particularly limited as long as it is a step for obtaining a mixture of the poly-L-lactic acid and the poly-D-lactic acid, and can be selected according to the purpose. For example, the following two methods Is mentioned.
In the production method (A), the mixing step (hereinafter referred to as “first method”) is performed by bringing the D-form lactide into contact with the poly-L-lactic acid in the presence of the compressive fluid. It is a step of obtaining a mixture of the poly-L-lactic acid and the poly-D-lactic acid by ring-opening polymerization of the D-form lactide.
In the production method (B), the mixing step (hereinafter referred to as “second method”) involves contacting the poly-L-lactic acid and the poly-D-lactic acid in the presence of the compressive fluid. And mixing them to obtain a mixture of the poly-L-lactic acid and the poly-D-lactic acid.

<<< First Method >>>
First, the first method will be described with reference to FIGS. 5A and 5B. 5A and 5B are schematic views showing an example of a mixing step in the production system of the stereocomplex polylactic acid resin composition used in the first method. In the first method, in the series 1 in the stereocomplex polylactic acid resin composition production system 200 of FIG. 5A, the poly-L- in the ring-opening polymerization step (also referred to as “the production method of the first embodiment”) described above. A polymer of lactic acid was produced, and the obtained polymer product P (the poly-L-lactic acid) and the newly introduced second ring-opening polymerizable monomer (D-form lactide) were compressed in series 2. A product of a stereocomplex polylactic acid resin composition that is a mixture of the poly-L-lactic acid and the poly-D-lactic acid by ring-opening polymerization of the D-form lactide by contact in the presence of a natural fluid PP (final polymer product) is obtained continuously. In addition, the stereocomplex polylactic acid resin composition which is product PP which has a 3 or more types of segment is obtained by repeating the series similar to the series 2 in the stereocomplex polylactic acid resin composition manufacturing system 200 of FIG. 5A in series. You can also

Then, the specific example of the stereocomplex polylactic acid resin composition manufacturing system 200 is demonstrated using FIG. 5B. The stereocomplex polylactic acid resin composition production system 200 includes a polymerization reaction device 100, tanks (21, 27), a metering feeder 22, a metering pump 28, and a melt-mixing device similar to those used in the first embodiment. An apparatus 29, a reaction vessel 33, and a pressure adjustment valve 34 are included.
In the stereocomplex polylactic acid resin composition manufacturing system 200, the polymer inlet 33 a of the reaction vessel 33 is connected to the outlet of the polymerization reaction device 100 via a pressure resistant pipe 31. Here, the outlet of the polymerization reaction apparatus 100 means the outlet of the reaction vessel 13, the metering pump 14 (FIG. 3), or the pressure regulating valve 16 (FIG. 4). In any case, the polymer product P generated in each polymerization reaction apparatus 100 can be supplied to the reaction vessel 33 in a molten state without returning to normal pressure.

  The tank 21 stores D-form lactide which is the second ring-opening polymerizable monomer. In the first method, the second ring-opening polymerizable monomer is an optical isomer of the ring-opening polymerizable monomer stored in the tank 1. The tank 27 stores a compressible fluid. The compressive fluid stored in the tank 27 is not particularly limited, but is preferably the same type as the compressive fluid stored in the tank 7 in order to advance the polymerization reaction uniformly. The tank 27 may store a gas (gas) or a solid that is a compressible fluid in the course of being supplied to the melt mixing device 29, or heated or pressurized in the melt mixing device 29. . In this case, the gas or solid stored in the tank 27 is heated or pressurized to be in the state of (1), (2), or (3) in the phase diagram of FIG. Become.

The metering feeder 22 measures the second ring-opening polymerizable monomer stored in the tank 21 and continuously supplies it to the melt mixing device 29. The metering pump 28 continuously supplies the compressive fluid stored in the tank 27 to the melt mixing device 29 at a constant pressure and flow rate. The melt mixing device 29 is a pressure-resistant container for continuously bringing the second ring-opening polymerizable monomer supplied from the tank 21 and the compressive fluid supplied from the tank 27 into contact with each other to melt the raw materials. It is a device that has. Into the container of the melt mixing device 29, the introduction port 29 a for introducing the compressive fluid supplied from the tank 27 by the metering pump 28 and the second ring-opening polymerizable monomer supplied from the tank 21 by the metering feeder 22 are introduced. And an introduction port 29b. In the present embodiment, as the melt mixing device 29, the same one as the melt mixing device 9 is used.
Total mass of raw materials supplied per unit time by metering feeder 22 and metering pump 28 (raw material feed rate, (g / min)) and compressive fluid feed rate (compressible fluid feed rate, (g / min)) ) Is adjusted.
The ratio of the compressible fluid feed amount to the raw material feed amount (raw material feed amount / compressible fluid feed amount, feed ratio) is preferably 1 or more, more preferably 3 or more, further preferably 5 or more, and more preferably 10 or more. Particularly preferred.
The upper limit of the feed ratio is preferably 1000 or less, more preferably 100 or less, and particularly preferably 50 or less.
In this embodiment, the value of the feed ratio used in the polymerization step to obtain the poly-L-lactic acid (feed ratio A1) and the feed ratio when the lactide of the D form is brought into contact with the compressive fluid. The ratio with the value (feed ratio B1) is preferably (feed ratio A1) :( feed ratio B1) = 4: 1 to 1: 1, and (feed ratio A1) :( feed ratio B1) = 1: 1 is more preferable.

  The reaction vessel 33 is obtained by polymerization in the polymerization reaction apparatus 100, and the polymer product P (the poly-L-lactic acid) as an intermediate in a state melted in the compressive fluid, and the compressive fluid in the melt mixing apparatus 29. This is a pressure-resistant container for polymerizing the second ring-opening polymerizable monomer (D-form lactide) melted in the container.

  Into the reaction vessel 33, the inlet 33a for introducing the molten polymer product P as an intermediate into the vessel and the molten second ring-opening polymerizable monomer are introduced into the vessel. An introduction port 33b is provided. In the present embodiment, the same reaction vessel 33 as the reaction vessel 13 is used.

The tank 51 stores a compressive fluid that is additionally supplied to the reaction vessel 33. The metering pump 52 continuously supplies the compressive fluid stored in the tank 51 to the reaction vessel 33.
The supply speed (compressive fluid feed amount, (g / min)) of the compressive fluid supplied per unit time by the metering pump 52 is adjusted.
The total feed amount combining the poly-L-lactic acid feed amount and the D-lactide feed amount, the remaining compressible fluid supplied to the reaction vessel by 33a, 33b, and the compressibility supplied by the metering pump 52 The ratio (feed ratio in the mixing step) to the total compressive fluid feed amount combined with the fluid is preferably as follows.
The total feed amount / compressible fluid total feed amount (feed ratio C1) is preferably 2.5 or more and 10 or less.

Although not shown, a pump for adjusting the feeding speed of the D-form lactide is provided at the introduction port 33b for introducing the second ring-opening polymerizable monomer (D-form lactide) into the reaction vessel 33. It may be installed.
In this embodiment, in order to obtain a desired stereocomplex polylactic acid resin composition, the feed rate of each pump when supplying the poly-L-lactic acid and the D-form lactide to the reaction vessel 33 may be adjusted.
As the feed rate of the poly-L-lactic acid and the feed rate of the lactide of the D-form, the feed rate of the poly-L-lactic acid: the feed rate of the poly-D-lactic acid = 98.00: 2.00 to 99 .95: 0.05 is preferred.

The pressure adjustment valve 34 sends out the stereocomplex polylactic acid resin composition, which is the product PP polymerized in the reaction vessel 33, to the outside of the reaction vessel 33 by utilizing the pressure difference between the inside and outside of the reaction vessel 33.
In the first method, the ring-opening polymerizable monomer (L-form lactide) is polymerized in the reaction vessel 13, and after the reaction is quantitatively completed, the second ring-opening polymerizable monomer (D-form lactide) is reacted. In addition to the container 33, a polymerization reaction is further performed. Thereby, the stereocomplex polylactic acid resin composition of a stereoblock copolymer is obtained. According to the method of the present embodiment, since the reaction can proceed at a temperature below the melting point of the ring-opening polymerizable monomer with a small amount of residual monomer, racemization is very unlikely and is very useful because it can be obtained in a one-step reaction. It is.

<<< Second Method >>>
Subsequently, the second method will be described with reference to FIG. FIG. 6 is a schematic diagram showing an example of a mixing step in the production system of the stereocomplex polylactic acid resin composition used in the second method. In the second method, a plurality of polymer products (the poly-L-lactic acid and the poly-D-lactic acid) respectively produced by the production method of the first embodiment are continuously added in the presence of a compressive fluid. To produce a product PP of a stereocomplex polylactic acid resin composition that is a mixture of the poly-L-lactic acid and the poly-D-lactic acid. The plurality of polymer products are obtained by polymerizing ring-opening polymerizable monomers of optical isomers to each other. The stereocomplex polylactic acid resin composition production system 300 includes a plurality of polymerization reaction devices 100, a mixing device 41, and a pressure adjustment valve 42.

  In the stereocomplex polylactic acid resin composition production system 300, the polymer inlet 41 a of the mixing device 41 is connected to the outlet of each polymerization reaction device 100 via the pressure resistant pipe 31. Here, the outlet of the polymerization reaction apparatus 100 means the outlet of the reaction vessel 13, the metering pump 14 (FIG. 3), or the pressure regulating valve 16 (FIG. 4). In any case, the polymer product P generated in each polymerization reaction device 100 can be supplied to the mixing device 41 in a molten state without returning to normal pressure. As a result, each polymer product P has a low viscosity in the presence of the compressive fluid, so that the mixing device 41 can mix two or more types of polymer products P at a lower temperature. 6 shows an example in which the piping 31 has one joint 31a so that two polymerization reaction apparatuses 100 are provided in parallel. However, by providing a plurality of joints, the polymerization reaction apparatus 100 can be connected in three in parallel. You may have more than one.

  In the present embodiment, a feed ratio value (referred to as feed ratio A2) set when the polymerization reactor 100 generates the poly-L-lactic acid, and the polymerization reactor 100 uses the poly-D- The ratio with the feed ratio value (feed ratio B2) set when producing lactic acid is preferably (feed ratio A2) :( feed ratio B2) = 4: 1 to 1: 1, (feed The ratio A2) :( feed ratio B2) = 1: 1 is more preferable.

Moreover, in this embodiment, in order to obtain a desired stereocomplex polylactic acid resin composition, the feed rate of each pump when supplying the poly-L-lactic acid and the poly-D-lactic acid to the mixing device 41 is adjusted. Good.
As the feed rate of the poly-L-lactic acid and the feed rate of the poly-D-lactic acid, the feed rate of the poly-L-lactic acid: the feed rate of the poly-D-lactic acid = 98.00: 2.00 99.95: 0.05 is preferred.

The mixing device 41 is not limited as long as it can mix a plurality of polymer products supplied from the respective polymerization reaction devices 100, but includes a device equipped with a stirring device. As the agitation device, a uniaxial screw, a biaxial screw that meshes with each other, a biaxial mixer having a large number of agitation elements that mesh with each other or overlap, a kneader having helical agitation elements that mesh with each other, a static mixer, etc. are preferably used. . The temperature (mixing temperature) at which each polymer product is mixed by the mixing device 41 can be set similarly to the polymerization reaction temperature in the reaction vessel 13.
The mixing device 41 is provided with an inlet 41a for introducing the polymer product to be mixed into the container and an inlet 41b for adjusting the concentration of the compressive fluid.
The tank 61 stores a compressive fluid that is additionally supplied to the mixing device 41. The metering pump 62 continuously supplies the compressive fluid stored in the tank 61 to the mixing device 41.
The supply speed (compressive fluid feed amount, (g / min)) of the compressive fluid supplied per unit time by the metering pump 62 is adjusted.
The total feed amount combining the poly-L-lactic acid feed amount and the poly-D-lactic acid feed amount, the remaining compressible fluid supplied to the mixing container by 41a, and the compressibility supplied by the metering pump 62 The ratio (feed ratio in the mixing step) to the total compressive fluid feed amount combined with the fluid is preferably as follows.
The total feed amount / compressible fluid total feed amount (feed ratio C2) is preferably 2.5 or more and 10 or less.
The pressure adjustment valve 42 is an apparatus for adjusting the flow rate of the stereocomplex polylactic acid resin composition that is the product PP obtained by mixing the polymer product with the mixing device 41.

  In the second method, L-form and D-form lactides are polymerized in advance in the compressive fluid in the polymerization reactor 100. Further, the polymer product obtained by polymerization is blended in a compressive fluid to obtain a stereocomplex polylactic acid resin composition of a stereoblock copolymer. In general, polymers such as polylactic acid often decompose when heated and dissolved again, even when the residual monomer is extremely small. The second method is useful because, by blending low-viscosity polylactic acid melted with a compressive fluid at a melting point or lower, racemization and thermal degradation can be suppressed as in the first method.

  Moreover, it is also possible to mix the block copolymer which forms a stereocomplex by combining the 1st method and the 2nd method.

<Molded product of stereocomplex polylactic acid resin composition>
Subsequently, a molded product obtained by molding the stereocomplex polylactic acid resin composition obtained by the above production method and a molded product of fiber will be described.

<< Molded product >>
In the present embodiment, the molded product refers to a product processed using a mold.
This molded product includes not only a molded product as a single unit, but also a part made of a molded product such as a handle of a tray and a product including a molded product such as a tray to which a handle is attached.
The processing method is not particularly limited and can be selected according to the purpose. For example, a conventionally known thermoplastic resin processing method can be used. Specifically, injection molding, vacuum molding, pressure molding, vacuum pressure molding, press molding and the like can be mentioned.
The stereocomplex polylactic acid resin composition obtained by the above production method can be melted and injection molded to obtain a molded product. Moreover, a molded article can also be obtained by press-molding a sheet made of the stereocomplex polylactic acid resin composition obtained by the above-described production method by die molding (giving a shape).
The processing conditions at the time of shaping are not particularly limited, and are appropriately selected based on the type of polymer product and the apparatus. For example, when a sheet made of the stereocomplex polylactic acid resin composition of the present embodiment is press-molded by mold molding, the mold temperature is preferably 100 ° C. or higher and 150 ° C. or lower. When molding by injection molding, when a polymer product heated to 150 ° C or higher and 250 ° C or lower is injected into a mold, the mold temperature is set to 20 ° C or higher and 80 ° C or lower, and processed by injection molding Good.

Conventionally, the polylactic acid resin composition that has been widely used has a high residual ratio of metal catalyst, organic solvent, and monomer. When such a polylactic acid resin composition is heated to form a sheet, for example, remaining foreign matters such as metal catalysts, organic solvents, and monomers appear in the form of fish eyes. There was a problem that it was lowered. Similar problems occur when molding is performed by mold molding or injection molding.
However, since the molded product according to the present embodiment uses a polymer product produced by a manufacturing method that does not use an organic solvent, it is substantially free of an organic solvent and the amount of residual monomer is extremely low at 1,000 ppm or less. Few. Further, by using an organic catalyst as the catalyst and suppressing the amount of the metal catalyst used, it is possible to obtain a molded product with a low content of metal atoms. Accordingly, the molded product obtained by the present embodiment is excellent in safety, stability, and appearance. Therefore, the molded product of the present embodiment is not particularly limited, but is widely applied as an application for industrial materials, daily necessities, agricultural products, food products, pharmaceutical products, cosmetics sheets, packaging materials, trays, and the like.

<< fiber >>
The stereocomplex polylactic acid resin composition obtained by the above production method can be applied to fibers such as monofilaments and multifilaments.
In this embodiment, the fiber includes not only a single fiber such as a monofilament, but also an intermediate product composed of fibers such as a woven fabric and a nonwoven fabric, and a product having a woven fabric and a nonwoven fabric such as a mask.
In the present embodiment, the fiberizing method for producing the monofilament is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a melt spinning, cooling, and stretching method using a conventionally known method. . The processing method is not particularly limited and can be selected according to the purpose. For example, a conventionally known thermoplastic resin processing method can be used. Specifically, injection molding, vacuum molding, pressure molding, vacuum pressure molding, press molding and the like can be mentioned.
Depending on the application, a coating layer may be formed on the monofilament using a conventionally known method. Moreover, the coating layer may contain an antibacterial agent, a coloring agent, and the like.

There is no restriction | limiting in particular as a method of manufacturing a nonwoven fabric, It can select according to the objective, For example, a conventionally well-known method can be used and the method of melt spinning, cooling, extending | stretching, opening, depositing, and heat processing is mentioned. .
The polymer product constituting the nonwoven fabric may contain additives such as antioxidants, flame retardants, ultraviolet absorbers, antistatic agents, antibacterial agents, and binder resins. The treatment for mixing the additive may be performed during the ring-opening polymerization step, the mixing step, or after those steps.
Since the fiber obtained by this embodiment uses the polymer product manufactured by the manufacturing method which does not use an organic solvent, the organic solvent is not contained and the amount of residual monomers is as very low as 1,000 ppm or less. In addition, by using an organic catalyst as the catalyst and suppressing the amount of the metal catalyst used, it is possible to form a fiber having a low metal atom content. As a result, the fiber obtained according to the present embodiment is excellent in safety and stability.
Therefore, the fiber of the present embodiment is not particularly limited, but if it is a monofilament, it can be widely applied as a fishing line, a fish net, a surgical suture, a medical material, an electrical equipment material, an automobile material, an industrial material, or the like. In addition, non-woven fabrics are widely used as fishery / agricultural materials, construction / civil engineering materials, interiors, automobile parts, packaging materials, daily goods, sanitary materials, and the like.

(Example 1)
After ring-opening polymerization of L-form lactide and D-form lactide using the polymerization reaction apparatus 100 of FIG. 3, the stereocomplex polylactic acid resin is produced using the stereocomplex polylactic acid resin composition production system 300 of FIG. A composition was prepared.
The structure of the stereocomplex polylactic acid resin composition manufacturing system 300 is shown.

The structure of the polymerization reaction apparatus 100 of FIG. 3 is shown.
Tank 1, weighing feeder 2:
Plunger pump NP-S462 made by Nippon Seimitsu
Tank 1 was filled with molten lactide as a ring-opening polymerizable monomer.
Tank 3, weighing feeder 4:
Intelligent HPLC pump manufactured by JASCO (PU-2080)
Tank 3 was filled with lauryl alcohol as an initiator.
Tank 5, metering pump 6: Not used in this example.
Tank 7: Carbon dioxide cylinder tank 11, metering pump 12:
Intelligent HPLC pump manufactured by JASCO (PU-2080)
The tank 11 was filled with DBU (organic catalyst).
Melt mixing device 9: biaxial stirring device with screws that mesh with each other
Cylinder inner diameter 30mm
Cylinder set temperature 100 ℃
2-axis rotation in the same direction
Rotation speed 30rpm
Reaction vessel 13: biaxial kneader
Cylinder inner diameter 40mm
Cylinder set temperature Raw material supply part 60 ℃ Tip part 60 ℃
2-axis rotation in the same direction
Rotation speed 60rpm

The melt mixing device 9 and the reaction vessel 13 were operated under the above set conditions.
Hereinafter, one of the plurality of polymerization reaction apparatuses 100 in the stereocomplex polylactic acid resin composition production system 300 is referred to as a series 1 polymerization reaction apparatus 100 and the other is referred to as a series 2 polymerization reaction apparatus 100.

The series 1 polymerization reaction apparatus 100 will be described.
The metering feeder 2 quantitatively supplied L-lactide in a molten state in the tank 1 (PURALACT® L: manufactured by Pulac Co., Ltd.) into the container of the melt mixing device 9. The measuring feeder 4 quantitatively supplied the lauryl alcohol in the tank 3 into the container of the melt mixing device 9 so as to be 0.1 mol with respect to the supply amount of L-lactide of 99.9 mol. The metering pump 8 feeds carbon dioxide (carbon dioxide) as a compressive fluid from the tank 7 such that the feed ratio = feed rate of raw materials (g / min) / supply rate of compressible fluid (g / min) is 20. Then, it was continuously supplied into the piping of the melt mixing device 9. The raw material here is L-lactide and lauryl alcohol added as an initiator. It supplied so that the pressure in the container of the melt mixing apparatus 9 might be set to 15 MPa. As a result, the melt mixing device 9 continuously brings the raw materials of lactide and lauryl alcohol supplied from the tanks (1, 3, 7) and the compressive fluid into contact with each other and mixes them with a screw. Was melted.

Each material melted by the melt mixing device 9 was sent to the reaction vessel 13 by the liquid feed pump 10. The metering pump 12 supplied the organic catalyst (DBU) in the tank 11 to the raw material supply hole of the biaxial kneader as the reaction vessel 13 so as to be 0.1 mol with respect to 99.9 mol of L-lactide. .
In the reaction vessel 13, each material fed by the liquid feeding pump 10 and DBU supplied by the metering pump 12 were mixed, and L-form lactide was subjected to ring-opening polymerization.
In this case, the average residence time of each material in the reaction vessel 13 was about 1,200 seconds.
A metering pump 14 and an extrusion cap 15 were attached to the tip of the reaction vessel 13. The feed rate of the polymer (poly-L-lactic acid) as the product of the metering pump 14 was 392 g / min.
The series 2 polymerization reaction apparatus 100 will be described.
In series 1, the L-form lactide of the material was changed to D-form lactide (PURALACT® D: manufactured by Pulac Co., Ltd.), and the feed rate of poly-D-lactic acid was changed to 8 g / min. Under the conditions, D-form lactide was polymerized to obtain poly-D-lactic acid.
Next, the mixing process in the manufacturing system 300 of the stereocomplex polylactic acid resin composition of FIG. 6 is demonstrated.
Each polymer product (poly-L-lactic acid, poly-D-lactic acid) obtained in each polymerization reaction apparatus 100 is directly mixed by each metering pump 14 in a molten state in the presence of a compressive fluid. The apparatus 41 was continuously supplied.
Mixing device 41: A biaxial stirring device with screws that mesh with each other
Cylinder inner diameter 40mm
2-axis rotation in the same direction
Rotation speed 30rpm
The temperature in the vicinity of the polymer product supply part and the tip of the cylinder of the mixing device 41 during mixing was 60 ° C.
Feed ratio = feed rate of poly-L-lactic acid and poly-D-lactic acid combined (g / min) / residual compressible fluid supplied by 41a to the mixing vessel and compressibility supplied by metering pump 62 The compressive fluid was additionally inserted into the mixing device 41 so that the compressive fluid supply speed (g / min) combined with the fluid was 10. The cylinder internal pressure was 15 MPa.
Each polymer product was stirred and continuously mixed with an average residence time of 600 seconds to obtain a stereocomplex polylactic acid resin composition.

  About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 1.

(Example 2)
A stereocomplex polylactic acid resin composition was obtained in the same manner as in Example 1 except that the in-cylinder pressure of the mixing device 41 was changed as shown in Table 1 in Example 1.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 1.

(Example 3)
A stereocomplex polylactic acid resin composition was obtained in the same manner as in Example 1 except that the in-cylinder pressure and feed ratio of the mixing device 41 were changed as shown in Table 1 in Example 1.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 1.

Example 4
A stereocomplex polylactic acid resin composition was obtained in the same manner as in Example 1 except that the feeding rates of L-form lactide and D-form lactide were changed as shown in Table 1 in Example 1.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 1.

(Example 5)
In Example 1, except having changed the cylinder temperature of the mixing apparatus 41 as described in Table 2, the same operation as Example 1 was performed and the stereocomplex polylactic acid resin composition was obtained.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 2.

(Example 6)
In Example 1, the same operation as in Example 1 was performed except that the cylinder temperature, the pressure in the cylinder, and the feed ratio of the mixing device 41 were changed as shown in Table 2, and a stereocomplex polylactic acid resin composition was obtained. .
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 2.

(Example 7)
In Example 1, except that the catalyst used for the polymerization of L-form lactide and D-form lactide was changed to tin octylate, and the cylinder temperature and internal pressure in the mixing step were changed as shown in Table 2. The same operation as in Example 1 was performed to obtain a stereocomplex polylactic acid resin composition.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 2.

(Example 8)
In Example 1, the catalyst used for the polymerization of L-form lactide and D-form lactide was changed to N, N-dimethyl-4-aminopyridine (DMAP), and the cylinder temperature and internal pressure in the mixing step were changed to Table 2. A stereocomplex polylactic acid resin composition was obtained in the same manner as in Example 1 except that the change was made as described in 1.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 2.

Example 9
Experiments were performed using the first method shown in FIGS. 5A and 5B. The operation performed in the polymerization reaction apparatus 100 in FIG. 5B is the same as the operation described in the series 1 polymerization reaction apparatus 100 of Example 1. In FIG. 5B, the conditions of the D-form lactide of the tank 21 supplied to the melt mixing device 29 and the carbon dioxide gas of the tank 27 are the same as the conditions described in the series 2 of the first embodiment. Although the catalyst (DBU) used when polymerizing the D-form lactide is not shown in FIG. 5B, a tank filled with a catalyst (catalyst) is separated from the lactide tank 21 as in the system 100. A tank) is supplied to the melt mixing device 29 using the catalyst tank and a pump.
The monomer feed rate of D-form lactide supplied to the reaction vessel 33 in FIG. 5B was 8 g / min as described in Table 3. The same operation as in Example 1 was performed except that the mixing device 41 of Example 1 was replaced with the reaction vessel 33 in Example 9 and the residence time in the mixing process of Example 1 was changed as described in Table 3. And a stereocomplex polylactic acid resin composition was obtained.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 3.

(Example 10)
The stereocomplex polylactic acid resin composition obtained in the same manner as in Example 1 was heated to 250 ° C., and a molded product was produced using a molding machine.
About the obtained molded product, physical property values (the Mn, the Mw / Mn, the polymer conversion rate, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half width, the YI value) , The amount of the organic solvent, the amount of the lactide, the amount of the metal catalyst). The results are shown in Table 3.

(Example 11)
The stereocomplex polylactic acid resin composition obtained in the same manner as in Example 1 was spun at 250 ° C. with a melt spinning apparatus (Musashinoki ST52).
About the obtained spinning, the physical property values (the Mn, the Mw / Mn, the polymer conversion rate, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half width, the YI value, The organic solvent amount, the lactide amount, and the metal catalyst amount) were determined. The results are shown in Table 3.

(Comparative Example 1)
In the mixing step, an experiment was performed in the same manner as in (Example 1) except that the compressive fluid was not added and the feed ratio in the mixing step was not changed from the polymerization step.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 4.

(Comparative Example 2)
In the mixing step, no compressible fluid is added, the feed ratio in the mixing step is not changed from the polymerization step, and the feed ratio in the polymerization step is set to the same value as the feed ratio in the mixing step of Example 1. The experiment was carried out in the same manner as in (Example 1) except that the changes were made as described in.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 4.

(Comparative Example 3)
The experiment was performed in the same manner as in Example 1 except that the polymer feed rate in the mixing step was changed as described in Table 5.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 5.

(Comparative Example 4)
The experiment was performed in the same manner as in (Example 7) except that the polymer feed rate in the mixing step was changed as described in Table 5.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 5.

(Comparative Example 5)
The experiment was performed in the same manner as in (Example 8) except that the polymer feed rate in the mixing step was changed as described in Table 5.
About the obtained stereocomplex polylactic acid resin composition, the physical property values (the Mn, the Mw / Mn, the polymer conversion, the stereocomplex formation rate, the optical purity, the crystal melting peak temperature, the half The value range, the YI value, the amount of organic solvent, the amount of lactide, the amount of metal catalyst) were determined. The results are shown in Table 5.

In Comparative Examples 1-2, it was not possible to obtain a stereocomplex polylactic acid resin composition with high optical purity that was not racemized.
In Comparative Examples 3 to 5, since the stereo complex formation rate was too low, the crystal melting peak temperature and the half width could not be improved, and a sufficient effect of heat resistance could not be confirmed.

Aspects of the present invention are as follows, for example.
<1> A stereocomplex polylactic acid resin composition having a stereocomplex formation rate of 0.5% to 2.0% and an optical purity of 96.0% to 99.9%. is there.
<2> The stereocomplex polylactic acid resin composition according to <1>, wherein the organic solvent amount is 1 ppm or less, the metal catalyst amount is 5 ppm or less, and the lactide amount is 1,000 ppm or less.
<3> The stereocomplex polylactic acid resin composition according to any one of <1> to <2>, wherein the number average molecular weight is 100,000 or more.
<4> The stereocomplex polylactic acid resin composition according to any one of <1> to <3>, wherein the YI (yellow index) value is 10 or less.
<5> A molded product comprising the stereocomplex polylactic acid resin composition according to any one of <1> to <4>.
<6> A fiber comprising the stereocomplex polylactic acid resin composition according to any one of <1> to <4>.
<7> An L-form lactide ring-opening polymerization step for obtaining poly-L-lactic acid by bringing a L-form lactide-containing raw material into contact with a compressive fluid and ring-opening polymerization of the L-form lactide;
The D-form lactide that has been brought into contact with the compressive fluid is brought into contact with the poly-L-lactic acid that is still in contact with the compressive fluid, and the D-form lactide is opened under the condition that the compressive fluid is further added. It is a manufacturing method of the stereocomplex polylactic acid resin composition characterized by including the mixing process of obtaining the mixture of the said poly-L-lactic acid and poly-D-lactic acid by making it ring-polymerize.
<8> An L-form lactide ring-opening polymerization step for obtaining poly-L-lactic acid by bringing a L-form lactide-containing raw material into contact with a compressive fluid to cause ring-opening polymerization of the L-form lactide;
A D-form lactide ring-opening polymerization step of obtaining poly-D-lactic acid by bringing a D-form lactide-containing raw material into contact with a compressive fluid and ring-opening polymerization of the D-form lactide;
The poly-L-lactic acid and the poly-D-lactic acid remaining in contact with the compressive fluid are brought into contact with and mixed with the poly-L-lactic acid and the poly-D-lactic acid in a state in which a compressive fluid is further added. It is a manufacturing method of the stereocomplex polylactic acid resin composition characterized by including the mixing process of obtaining the mixture with poly-D-lactic acid.
<9> The method for producing a stereocomplex polylactic acid resin composition according to any one of <7> to <8>, wherein the compressive fluid is carbon dioxide.

1, 3, 5, 7, 11, 21, 27, 51, 61 Tank 2, 4, 22 Metering feeder 6, 8, 12, 14, 28, 52, 62 Metering pump 9, 29 Melt mixing device 9a Inlet ( Example of compressible fluid inlet)
9b Inlet (Example of monomer inlet)
10 Liquid feed pumps 13, 33 Reaction vessel 13a Inlet 13b Inlet (an example of a catalyst inlet)
15 Extrusion cap (Example of polymer discharge port)
16 Pressure regulating valves 30, 31 Pipe 33a Inlet (an example of poly-L-lactic acid inlet)
33b inlet (an example of D-form lactide inlet)
41a Inlet (Poly-L-lactic acid and poly-D-lactic acid, an example of common inlet)
34 Pressure control valve (an example of a stereocomplex polylactic acid resin composition outlet)
42 Pressure adjustment valve (an example of a stereocomplex polylactic acid resin composition outlet)
41 Mixer (an example of a stereo complex polylactic acid resin composition continuous production device)
100 Polymerization Reaction Device 100a Supply Device 100b Polymerization Reaction Device Body (Example of Continuous Polymer Production Device)
200, 300 Stereocomplex polylactic acid resin composition production system P Polymer product PP product (stereocomplex polylactic acid resin composition)

JP 2012-188656 A JP 2013-189620 A

Claims (9)

  A stereocomplex polylactic acid resin composition having a stereocomplex formation rate of 0.5% to 2.0% and an optical purity of 96.0% to 99.9%.   The stereocomplex polylactic acid resin composition according to claim 1, wherein the amount of organic solvent is 1 ppm or less, the amount of metal catalyst is 5 ppm or less, and the amount of lactide is 1,000 ppm or less.   The stereocomplex polylactic acid resin composition according to claim 1, wherein the number average molecular weight is 100,000 or more.   The stereocomplex polylactic acid resin composition according to any one of claims 1 to 3, having a YI (yellow index) value of 10 or less.   A molded article comprising the stereocomplex polylactic acid resin composition according to any one of claims 1 to 4.   A fiber comprising the stereocomplex polylactic acid resin composition according to any one of claims 1 to 4. An L-form lactide ring-opening polymerization step for obtaining poly-L-lactic acid by bringing a L-form lactide-containing raw material into contact with a compressive fluid and ring-opening polymerization of the L-form lactide;
The D-form lactide that has been brought into contact with the compressive fluid is brought into contact with the poly-L-lactic acid that is still in contact with the compressive fluid, and the D-form lactide is opened under the condition that the compressive fluid is further added. A method for producing a stereocomplex polylactic acid resin composition comprising a mixing step of obtaining a mixture of poly-L-lactic acid and poly-D-lactic acid by ring polymerization. An L-form lactide ring-opening polymerization step for obtaining poly-L-lactic acid by bringing a L-form lactide-containing raw material into contact with a compressive fluid and ring-opening polymerization of the L-form lactide;
A D-form lactide ring-opening polymerization step of obtaining poly-D-lactic acid by bringing a D-form lactide-containing raw material into contact with a compressive fluid and ring-opening polymerization of the D-form lactide;
The poly-L-lactic acid and the poly-D-lactic acid remaining in contact with the compressive fluid are brought into contact with and mixed with the poly-L-lactic acid and the poly-D-lactic acid in a state in which a compressive fluid is further added. A method for producing a stereocomplex polylactic acid resin composition, comprising a mixing step of obtaining a mixture with poly-D-lactic acid. The method for producing a stereocomplex polylactic acid resin composition according to any one of claims 7 to 8, wherein the compressive fluid is carbon dioxide.