WO2014129293A1

WO2014129293A1 - Polylactic resin composition, molded product, and method for producing polylactic resin composition

Info

Publication number: WO2014129293A1
Application number: PCT/JP2014/052384
Authority: WO
Inventors: 高橋佳丈; 直塚拓磨; 大目裕千
Original assignee: 東レ株式会社
Priority date: 2013-02-19
Filing date: 2014-02-03
Publication date: 2014-08-28
Also published as: TW201437251A; JPWO2014129293A1

Abstract

Disclosed is a polylactic resin composition made by blending: a polylactic acid block copolymer that is constituted by poly-L-lactic acid segments including L-lactic acid as a main component, and poly-D-lactic acid segments including D-lactic acid as a main component; and a polymer that includes a plurality of reactive groups in a single molecule. Also disclosed is a method for producing said polylactic resin composition. The present invention provides: a polylactic resin composition that has improved mechanical properties, durability, and residence stability during heating, and that has excellent heat resistance and crystallization characteristics; a molded product; and a method for producing said polylactic resin composition.

Description

Polylactic acid resin composition, molded body, and method for producing polylactic acid resin composition

The present invention provides a polylactic acid resin composition, a molded article, and a polylactic acid resin composition that have improved molding processability, mechanical properties, durability, and stability during heating, and also excellent heat resistance and crystallization characteristics. It relates to a manufacturing method.

Polylactic acid is a polymer that can be melt-molded practically and has characteristics of biodegradability, so it is developed as a biodegradable plastic that is decomposed in the natural environment and released as carbon dioxide or water after use. Has been promoted. On the other hand, in recent years, polylactic acid itself is made from renewable resources (biomass) originating from carbon dioxide and water, so carbon that does not increase or decrease in the global environment even if carbon dioxide is released after use. Neutral properties have attracted attention and are expected to be used as environmentally friendly materials. Furthermore, lactic acid, which is a monomer of polylactic acid, is being produced at low cost by fermentation using microorganisms, and has been studied as an alternative material for general-purpose polymers made of petroleum-based plastics.

In patent document 1, the physical property improvement suitable for the shaping | molding process to a film or a sheet | seat is performed by melt-kneading the unsaturated carboxylic acid alkylester polymer which uses acrylic acid ester as a raw material monomer with respect to polylactic acid resin. Yes. In this technique, a molded body can be obtained without bleeding out during the molding process of the polylactic acid resin composition, and the obtained molded body has characteristics of excellent flexibility and transparency.

In Patent Document 2, the moldability of polylactic acid resin is improved by melt-kneading an acrylic resin-based modifier containing an epoxy group with respect to polylactic acid resin. In this technology, the epoxy group of the acrylic resin-based modifier reacts with the carboxyl group or hydroxyl group present at the end of the polylactic acid resin to form an appropriate cross-linked structure, thereby increasing the viscosity, which is suitable for molding. Is expressed.

Patent Document 3 describes that impact resistance of a polylactic acid resin composition can be improved by blending an acrylic resin with a polylactic acid resin composition composed of a polylactic acid resin and an ABS resin. Also in this technology, a reactive compound containing an epoxy group is exemplified as an acrylic resin, and the melt viscosity increases due to the reaction between the acrylic resin and the polylactic acid resin composition, in addition to impact resistance, thermal stability. Will also improve.

Patent Document 4 discloses that a polylactic acid stereocomplex composed of poly-L-lactic acid and poly-D-lactic acid is melt-kneaded with an acrylic resin containing an epoxy group to suppress a change in melt viscosity, and is stable against moisture and heat. A polylactic acid resin composition excellent in properties and color tone is obtained. In this technology, polylactic acid composed of poly-L-lactic acid and poly-D-lactic acid is used as the polylactic acid resin, and therefore it has a stereocomplex crystal phase, so that it has higher heat resistance than poly-L-lactic acid alone. Excellent in properties.
JP 2003-286401 A JP 2006-265399 A International Publication 2012-1111587 JP 2010-168505 A

However, polylactic acid has lower heat resistance and durability than petroleum-based plastics, and its crystallization speed is low, so it is inferior in productivity, and the range of practical use is greatly limited. .

The use of polylactic acid stereocomplex is expected as a means to solve the disadvantages of polylactic acid. The polylactic acid stereocomplex is formed by mixing optically active poly-L-lactic acid and poly-D-lactic acid. The melting point of the polylactic acid stereocomplex reaches 220 ° C., which is 50 ° C. higher than the melting point 170 ° C. of the polylactic acid homopolymer. Usually, a polylactic acid stereocomplex is formed by mixing poly-L-lactic acid and poly-D-lactic acid in a solution state or by heating and melt-mixing poly-L-lactic acid and poly-D-lactic acid. When a high molecular weight poly-L-lactic acid and a high molecular weight poly-D-lactic acid are heat-melted and mixed, there are many melting points of polylactic acid homopolymer even when the mixing composition ratio is 50:50. Therefore, at present, a material having both heat resistance and durability cannot be obtained.

On the other hand, a polylactic acid block copolymer is attracting attention as a new method for forming a polylactic acid stereocomplex. This polylactic acid block copolymer is obtained by covalently bonding a poly-L-lactic acid segment containing L-lactic acid as a main component and a poly-D-lactic acid segment containing D-lactic acid as a main component. Even so, since the stereocomplex crystal formability is excellent and the melting point derived from the stereocomplex crystal is observed, it is possible to obtain a material having excellent thermal properties such as heat resistance and crystallization characteristics. For this reason, the application as a high melting point and highly crystalline fiber, film, and resin molded article is tried.

In the molding process of polylactic acid, it is heated and melted above the melting point of the polymer and then shaped into the desired shape. However, when melted and retained at high temperatures, the melt viscosity generally decreases greatly, so for example in sheet film extrusion molding The thickness and width are not uniform, which may cause perforation of the sheet and poor stretching of the film. In thermoforming and blow molding, it tends to draw down during heating, so that the dimensional stability of the molded body is poor. Therefore, in the melt molding process of polylactic acid or stereocomplex, the molding conditions such as lowering the heating temperature are controlled to obtain a melt viscosity suitable for molding, but the molding temperature range is narrow and the molding processability is low. There's a problem. Therefore, as one of the methods to suppress the decrease in viscosity when polylactic acid is heated and melted and improve molding processability, melt and mix acrylic resin-based reactive compounds with polylactic acid and stereocomplex. Attempts have been made to improve the viscosity. In addition, since the molded product after melt molding of polylactic acid or stereocomplex has high rigidity and brittleness, in applications where flexibility is required, acrylic resin reactive compounds are melt-mixed in the same way as above. Thus, attempts are being made to improve physical properties (see, for example, Patent Documents 1 to 4).

However, in Patent Documents 1 to 3, although the processability at the time of melting of the polylactic acid resin is improved, the crystallization speed of the polylactic acid is so slow that it does not show the temperature-falling crystallization temperature. However, productivity remains a problem. Furthermore, since the melting point of homopolylactic acid is around 170 ° C., there remains a problem in heat resistance in actual use.

In addition, the polylactic acid stereocomplex prepared by melt-mixing poly-L-lactic acid and poly-D-lactic acid in Patent Document 4 has a high melting point, but the crystallization speed is insufficient, so that it is the same as Patent Documents 1 to 3. However, productivity remains a problem. In addition, in order to form a stereocomplex phase, an organophosphate metal salt or the like is added, so that a large amount of gas is generated at the time of heating and melting, such as having moldability, heat resistance, and crystallization characteristics. Nothing is available at present.

The present invention has been made in view of the above, and has improved mechanical properties, durability, retention stability during heating, and further forms polylactic acid stereocomplex having excellent heat resistance and crystallization characteristics. It is providing the manufacturing method of a resin composition, a molded object, and a polylactic acid resin composition. In particular, after the polylactic acid resin composed of a polylactic acid block copolymer is thickened with a polymer having a plurality of reactive groups per molecule, the crystallization characteristics do not deteriorate, and the molding processability, heat resistance, and crystallization characteristics The purpose is to achieve both.

In order to solve the above-described problems, the polylactic acid resin composition of the present invention has the following configuration. That is,
(A) 100 parts by weight of a polylactic acid block copolymer composed of a poly-L-lactic acid segment containing L-lactic acid as a main component and a poly-D-lactic acid segment containing D-lactic acid as a main component (B ) A polylactic acid resin composition comprising 0.05 to 2 parts by weight of a polymer having a plurality of reactive groups per molecule, and (B) a weight average of the polymers having a plurality of reactive groups per molecule Crystallization when the molecular weight is 1,000 to 15,000 and the polylactic acid resin composition is heated to 250 ° C. and kept at a constant temperature for 3 minutes and then cooled at a cooling rate of 20 ° C./min in DSC measurement. A polylactic acid resin composition having a calorific value of 10 J / g or more.

In the polylactic acid resin composition of the present invention, (B) the polymer having a plurality of reactive groups per molecule is preferably an epoxy group-containing acrylic resin-based reactive compound.

The polylactic acid resin composition of the present invention preferably has 2 to 30 epoxy groups per molecule of the epoxy group-containing acrylic resin reactive compound.

The polylactic acid resin composition of the present invention preferably has a stereocomplex formation rate (Sc) satisfying the following formula (1).

Sc = ΔHh / (ΔHl + ΔHh) × 100 ≧ 80 (1)
here,
ΔHh: Amount of heat (J / g) based on the stereocomplex crystal when the polylactic acid resin composition is heated at a rate of temperature increase of 20 ° C./min in the DSC measurement.
ΔHl: Calorie (J / g) based on crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal when heated at a rate of temperature increase of 20 ° C./min in DSC measurement of polylactic acid resin composition
Further, the polylactic acid resin composition of the present invention is a ratio of the melt flow rate after 10 minutes (MFR10) to the melt flow rate after 20 minutes (MFR20) at 230 ° C. and 21.2 N load conditions of the polylactic acid resin composition. It is preferable that (MFR10 / MFR20) is 0.5 or more and 2 or less.

Further, the polylactic acid resin composition of the present invention is a polylactic acid obtained when the polylactic acid resin composition is heated to 250 ° C. and kept at a constant temperature for 3 minutes in DSC measurement, and then cooled at a cooling rate of 20 ° C./min. It is preferable that the temperature-falling crystallization temperature of a resin composition is 130 degreeC or more.

In the polylactic acid resin composition of the present invention, the (A) polylactic acid block copolymer is prepared by mixing poly-L-lactic acid or poly-D-lactic acid under the conditions of the following combination 1 and / or the following combination 2. In addition, a mixture satisfying the following formula (2) having a weight average molecular weight of 90,000 or more and a stereocomplex formation rate (Sc) is obtained, and then obtained by solid phase polymerization at a temperature lower than the melting point of the mixture. It is preferable.
(Combination 1) The weight average molecular weight of either poly-L-lactic acid or poly-D-lactic acid is 60,000 to 300,000, and the other weight average molecular weight is 10,000 to 100,000 (Combination 2). The ratio of the weight average molecular weight of poly-L-lactic acid to the weight average molecular weight of poly-D-lactic acid is 2 or more and less than 30 Sc = ΔHh / (ΔHl + ΔHh) × 100> 60 (2)
here,
ΔHh: calorific value (J / g) based on stereocomplex crystals when the temperature is raised at a rate of temperature rise of 20 ° C./min in DSC measurement of a mixture of poly-L-lactic acid and poly-D-lactic acid
ΔHl: Crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal when heated at a rate of temperature increase of 20 ° C./min in DSC measurement of a mixture of poly-L-lactic acid and poly-D-lactic acid Heat quantity based on (J / g)
In the polylactic acid resin composition of the present invention, the (A) polylactic acid block copolymer is prepared by mixing poly-L-lactic acid or poly-D-lactic acid under the conditions of the following combination 3 and / or the following combination 4. In addition, a mixture satisfying the following formula (2) having a weight average molecular weight of 90,000 or more and a stereocomplex formation rate (Sc) is obtained, and then obtained by solid phase polymerization at a temperature lower than the melting point of the mixture. It is preferable.
(Combination 3) The weight average molecular weight of either poly-L-lactic acid or poly-D-lactic acid is 120,000 to 300,000, and the other weight average molecular weight is 30,000 to 100,000 (Combination 4) The ratio of the weight average molecular weight of poly-L-lactic acid to the weight average molecular weight of poly-D-lactic acid is 2 or more and less than 30.

Sc = ΔHh / (ΔHl + ΔHh) × 100> 60 (2)
here,
ΔHh: calorific value (J / g) based on stereocomplex crystals when the temperature is raised at a rate of temperature rise of 20 ° C./min in DSC measurement of a mixture of poly-L-lactic acid and poly-D-lactic acid
ΔHl: Crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal when heated at a rate of temperature increase of 20 ° C./min in DSC measurement of a mixture of poly-L-lactic acid and poly-D-lactic acid Heat quantity based on (J / g)
In the polylactic acid resin composition of the present invention, in the above invention, the polylactic acid resin composition preferably has a weight average molecular weight of 100,000 to 500,000.

In the above invention, the polylactic acid resin composition of the present invention preferably further comprises (b) poly-L-lactic acid and / or (c) poly-D-lactic acid, relative to the polylactic acid resin composition. .

Moreover, in order to solve the said subject, the molded object of this invention has the following structure. That is,
It is the molded object which consists of the said polylactic acid resin composition.

Further, in the molded article of the present invention, the relative crystallinity of the molded article is preferably 90% or more, and the haze value of the molded article having a thickness of 1 mm is preferably 10% or less.

Relative crystallinity = [(ΔHm−ΔHc) / ΔHm] × 100 (3)
here,
ΔHm: Crystal melting enthalpy of compact (J / g)
ΔHc: Crystallization enthalpy at elevated temperature of the compact (J / g)
In order to solve the above problems, the method for producing a polylactic acid resin composition of the present invention has any one of the following configurations (I) to (III). That is,
(I) Poly-L-lactic acid in which the weight average molecular weight of either poly-L-lactic acid or poly-D-lactic acid is 60,000 to 300,000 and the other weight average molecular weight is 10,000 to 100,000 And poly-D-lactic acid, or poly-L-lactic acid and poly-D-lactic acid in which the ratio of the weight average molecular weight of poly-L-lactic acid to the weight average molecular weight of poly-D-lactic acid is 2 or more and less than 30 And after solid phase polymerization at a temperature lower than the melting point of the mixture,
(B) A method for producing a polylactic acid resin composition comprising blending a polymer having a plurality of reactive groups in one molecule,
Or
(II) Poly-L-lactic acid in which the weight average molecular weight of either poly-L-lactic acid or poly-D-lactic acid is 60,000 to 300,000 and the other weight average molecular weight is 10,000 to 100,000 And poly-D-lactic acid, or poly-L-lactic acid and poly-D-lactic acid in which the ratio of the weight average molecular weight of poly-L-lactic acid to the weight average molecular weight of poly-D-lactic acid is 2 or more and less than 30 After
(B) blending a polymer having a plurality of reactive groups in one molecule,
A method for producing a polylactic acid resin composition, which is solid-phase polymerized at a temperature lower than the melting point of the mixture;
Or
(III) Poly-L-lactic acid in which one of poly-L-lactic acid and poly-D-lactic acid has a weight average molecular weight of 60,000 to 300,000 and the other has a weight average molecular weight of 10,000 to 100,000 And poly-D-lactic acid and (B) a polymer having a plurality of reactive groups in one molecule, or the ratio of the weight average molecular weight of poly-L-lactic acid to the weight average molecular weight of poly-D-lactic acid A poly-L-lactic acid and a poly-D-lactic acid having a molecular weight of 2 or more and less than 30, and (B) a polymer having a plurality of reactive groups in one molecule,
A method for producing a polylactic acid resin composition, which undergoes solid phase polymerization at a temperature lower than the melting point of the mixture.

According to the present invention, it is possible to provide a polylactic acid resin composition having improved mechanical properties, durability, and stability during heating, and also excellent heat resistance and crystallization characteristics. Since this polylactic acid resin contains a polylactic acid block copolymer as a constituent component, not only the molding processability of the polylactic acid resin composition and the retention stability during heating are improved, but also the crystallization characteristics are excellent. .

Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not limited by the following embodiment.

Hereinafter, the present invention will be described in detail.
<Polylactic acid block copolymer>
In the present invention, a polylactic acid block copolymer composed of a poly-L-lactic acid segment containing L-lactic acid as a main component and a poly-D-lactic acid segment containing D-lactic acid as a main component is an L-lactic acid unit. And a polylactic acid block copolymer in which a segment comprising D-lactic acid units is covalently bonded.

Here, the segment composed of L-lactic acid units is a polymer containing L-lactic acid as a main component, and means a polymer containing 70 mol% or more of L-lactic acid units. The content is more preferably 80 mol% or more, further preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 98 mol% or more.

The segment composed of D-lactic acid units is a polymer containing D-lactic acid as a main component, and means a polymer containing 70 mol% or more of D-lactic acid units. The content is more preferably 80 mol% or more, further preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 98 mol% or more.

In the present invention, the segment composed of L-lactic acid or D-lactic acid unit contains other components as long as the performance of the polylactic acid block copolymer and the polylactic acid resin composition containing the polylactic acid block copolymer is not impaired. Units may be included. Examples of component units other than L-lactic acid or D-lactic acid units include polycarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, and lactones. Specific examples include succinic acid, adipic acid, sebacic acid, Polycarboxylic acids such as fumaric acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid or their derivatives, ethylene glycol, propylene glycol, butane Ethylene oxide or propylene oxide was added to diol, pentanediol, hexanediol, octanediol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, trimethylolpropane or pentaerythritol Polyhydric alcohols, aromatic polyhydric alcohols obtained by addition reaction of ethylene oxide with bisphenol, polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol or their derivatives, glycolic acid, 3-hydroxybutyric acid, 4-hydroxy Hydroxycarboxylic acids such as butyric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, and glycolide, ε-caprolactone glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, and lactones such as δ-valerolactone.

In the present invention, the polylactic acid block copolymer has a melting point based on a stereocomplex crystal in the range of 190 to 230 ° C. due to the formation of a stereocomplex, and therefore has excellent heat resistance as compared with a polylactic acid homopolymer. A preferable range of the melting point derived from the stereocomplex crystal is 200 ° C. to 230 ° C., a temperature range of 205 ° C. to 230 ° C. is more preferable, and a temperature range of 210 ° C. to 230 ° C. is particularly preferable. Further, it may have a small melting peak based on a poly-L-lactic acid single crystal and / or a poly-D-lactic acid single crystal in the range of 150 ° C. to 185 ° C.

The polylactic acid block copolymer obtained in the present invention preferably has a stereocomplex formation rate (Sc) in the range of 80 to 100% from the viewpoint of heat resistance. More preferably, it is in the range of 85 to 100%, and particularly preferably 90 to 100%. Here, the stereocomplex formation rate is the ratio of the stereocomplex crystals in all the crystals in polylactic acid. Specifically, the crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal when the temperature is increased from 30 ° C. to 250 ° C. at a temperature rising rate of 20 ° C./min with a differential scanning calorimeter (DSC). It is possible to calculate by the following formula (4), where ΔH1 is the amount of heat based on and ΔHh is the amount of heat based on crystal melting of the stereocomplex crystal.

Sc = ΔHh / (ΔHl + ΔHh) × 100 (4)
In the present invention, the polylactic acid block copolymer preferably further satisfies the following formula (5).

1 <(Tm−Tms) / (Tme−Tm) <1.8 (5)
Here, Tm is a melting point when a polylactic acid block copolymer is heated from 30 ° C. to 250 ° C. at a temperature rising rate of 40 ° C./min by a differential scanning calorimeter (DSC), and Tms is a polylactic acid block The melting start temperature when the copolymer is heated from 30 ° C. to 250 ° C. at a rate of temperature increase of 40 ° C./min by a differential scanning calorimeter (DSC), Tme is the differential scanning calorimeter of the polylactic acid block copolymer (DSC) shows the melting end temperature when the temperature is raised from 30 ° C. to 250 ° C. at a temperature raising rate of 40 ° C./min. A preferable range is 1 <(Tm−Tms) / (Tme−Tm) <1.6, and a range of 1 <(Tm−Tms) / (Tme−Tm) <1.4 is more preferable.

In the present invention, the polylactic acid block copolymer preferably has a temperature-falling crystallization temperature (Tc) of 130 ° C. or higher in terms of excellent moldability and heat resistance. Here, the temperature drop crystallization temperature (Tc) of the compact is a constant temperature state at 250 ° C. for 3 minutes after being heated from 30 ° C. to 250 ° C. at a temperature rising rate of 20 ° C./min by a differential scanning calorimeter (DSC). Is a crystallization temperature derived from polylactic acid crystals measured when the temperature is lowered at a cooling rate of 20 ° C./min. The crystallization temperature (Tc) is not particularly limited, but is preferably 130 ° C. or higher, more preferably 132 ° C. or higher, and particularly preferably 135 ° C. or higher from the viewpoint of heat resistance and transparency.

The weight average molecular weight of the polylactic acid block copolymer of the present invention is not particularly limited, but is preferably 100,000 or more and less than 300,000 from the viewpoint of mechanical properties. More preferably, it is 120,000 or more and less than 280,000, more preferably 130,000 or more and less than 270,000, particularly preferably 140,000 or more and less than 260,000 from the viewpoint of moldability and mechanical properties.

The dispersion degree of the polylactic acid block copolymer is preferably in the range of 1.5 to 3.0 from the viewpoint of mechanical properties. The range of the degree of dispersion is more preferably 1.8 to 2.7, and 2.0 to 2.4 is particularly preferable in terms of moldability and mechanical properties. The weight average molecular weight and dispersity are values in terms of standard polymethyl methacrylate as measured by gel permeation chromatography (GPC) using hexafluoroisopropanol or chloroform as a solvent.

In the present invention, the average chain length of the polylactic acid block copolymer is preferably 20 or more. More preferably, it is 25 or more, and 30 or more is particularly preferable from the viewpoint of mechanical properties of the molded article. The average chain length of the polylactic acid block copolymer was determined by ¹³ C-NMR measurement, and the integrated value of the peak existing in the vicinity of 170.1 to 170.3 ppm of the carbon peak attributed to carbonyl carbon is (a). , 169.8 to 170.0 ppm, where (b) is the integrated value of the peak, it can be calculated by the following equation (6).

Average chain length = (a) / (b) (6)
In the present invention, the total number of segments consisting of L-lactic acid units and segments consisting of D-lactic acid units contained in one molecule of the polylactic acid block copolymer is 3 or more. It is preferable in that a polylactic acid block copolymer that easily forms can be obtained. More preferably, it is 5 or more, and it is especially preferable that it is 7 or more.

In the present invention, the total weight ratio of the segment composed of L-lactic acid units and the segment composed of D-lactic acid units is preferably 90:10 to 10:90. More preferably, it is 80:20 to 20:80, and particularly preferably 75:25 to 60:40 or 40:60 to 25:75. When the total weight ratio of the segment consisting of L-lactic acid units and the segment consisting of D-lactic acid units is within the above preferred range, a polylactic acid stereocomplex can be easily formed. As a result, the melting point of the polylactic acid block copolymer The rise of is sufficiently large.
<Preparation method of polylactic acid block copolymer>
The method for preparing the polylactic acid block copolymer is not particularly limited, and a general method for preparing polylactic acid can be used. Specifically, ring-opening polymerization is performed in the presence of a catalyst on either a cyclic dimer L-lactide or D-lactide produced from lactic acid as a raw material, and lactide which is an optical isomer of the polylactic acid is further obtained. A lactide method in which a polylactic acid block copolymer is obtained by addition and ring-opening polymerization (preparation method 1 of a polylactic acid block copolymer), and the raw material is polymerized directly or by ring-opening polymerization via lactide. A method of polymerizing lactic acid and poly-D-lactic acid, and then mixing the obtained poly-L-lactic acid and poly-D-lactic acid and then obtaining a polylactic acid block copolymer by solid phase polymerization (polylactic acid block) Copolymer preparation method 2) The segment of the L-lactic acid unit is obtained by subjecting poly-L-lactic acid and poly-D-lactic acid to melt-kneading for a long time at a temperature higher than the melting end temperature of the component having the higher melting point. And D-lactic acid unit A method of obtaining a polylactic acid block copolymer obtained by transesterification with a polymentine (preparation method 3 of a polylactic acid block copolymer), and mixing a polyfunctional compound with poly-L-lactic acid and poly-D-lactic acid. There is a method in which poly-L-lactic acid and poly-D-lactic acid are covalently bonded with a polyfunctional compound to obtain a polylactic acid block copolymer by the reaction (preparation method 4 of polylactic acid block copolymer). . Any method may be used as a preparation method, but a method of solid-phase polymerization after mixing poly-L-lactic acid and poly-D-lactic acid is included in one molecule of polylactic acid block copolymer. -The total number of segments consisting of lactic acid units and segments consisting of D-lactic acid units is 3 or more, which is preferable in that a polylactic acid block copolymer having heat resistance, crystallinity and mechanical properties can be obtained.

Here, poly-L-lactic acid is a polymer containing L-lactic acid as a main component, and means a polymer containing 70 mol% or more of L-lactic acid units. It is preferable to contain 80 mol% or more, more preferably 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 98 mol% or more.

Poly-D-lactic acid is a polymer containing D-lactic acid as a main component, and means a polymer containing 70 mol% or more of D-lactic acid units. It is preferable to contain 80 mol% or more, more preferably 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 98 mol% or more.

Next, a method for preparing various polylactic acid block copolymers will be described in detail.

As a method for preparing a polylactic acid block copolymer by ring-opening polymerization (Preparation Method 1), for example, either L-lactide or D-lactide is subjected to ring-opening polymerization in the presence of a catalyst, and then the other optical An example is a method of obtaining a polylactic acid block copolymer by carrying out ring-opening polymerization by adding lactide which is an isomer.

The ratio of the weight average molecular weight of the segment consisting of L-lactic acid units and the weight average molecular weight of the segment consisting of D-lactic acid units contained in one molecule of the polylactic acid block copolymer obtained by ring-opening polymerization is as follows. From the viewpoint of transparency, it is preferably 2 or more and less than 30. More preferably, it is 3 or more and less than 20, and particularly preferably 5 or more and less than 15. Here, the ratio of the weight average molecular weight of the segment consisting of L-lactic acid units to the weight average molecular weight of the segments consisting of D-lactic acid units is such that L-lactide and D-lactide used for polymerizing the polylactic acid block copolymer The weight ratio can be controlled.

The total number of segments composed of L-lactic acid units and segments composed of D-lactic acid units contained in one molecule of the polylactic acid block copolymer obtained by ring-opening polymerization is 3 or more, and the heat resistance and crystallinity are It is preferable in terms of improvement. More preferably, it is 5 or more, and it is especially preferable that it is 7 or more. The weight average molecular weight per segment is preferably 2,000 to 50,000. More preferably, it is 4,000 to 45,000, and particularly preferably 5,000 to 40,000.

The optical purity of L-lactide and D-lactide used in the ring-opening polymerization method is preferably 90% ee or more from the viewpoint of improving the crystallinity and melting point of the polylactic acid block copolymer. More preferably, it is 95% ee or more, and it is especially preferable that it is 98% ee or more.

When obtaining a polylactic acid block copolymer by the ring-opening polymerization method, the water content in the reaction system is 4 mol% or less with respect to the total amount of L-lactide and D-lactide from the viewpoint of obtaining a high molecular weight product. preferable. More preferably, it is 2 mol% or less, and 0.5 mol% or less is particularly preferable. The water content is a value measured by a coulometric titration method using the Karl Fischer method.

Examples of the polymerization catalyst for preparing the polylactic acid block copolymer by the ring-opening polymerization method include a metal catalyst and an acid catalyst. Examples of the metal catalyst include tin catalysts, titanium compounds, lead compounds, zinc compounds, cobalt compounds, iron compounds, lithium compounds, and rare earth compounds. As the kind of the compound, metal alkoxide, metal halogen compound, organic carboxylate, carbonate, sulfate, oxide and the like are preferable. Specifically, tin powder, tin (II) chloride, tin (IV) chloride, tin (II) bromide, tin (IV) bromide, ethoxy tin (II), t-butoxy tin (IV), isopropoxy Tin (IV), tin (II) acetate, tin (IV) acetate, tin (II) octylate, tin (II) laurate, tin (II) myristate, tin (II) palmitate, tin stearate (II) ), Tin (II) oleate, tin (II) linoleate, tin (II) acetylacetone, tin (II) oxalate, tin (II) lactate, tin (II) tartrate, tin (II) pyrophosphate, p- Phenol sulfonate tin (II), bis (methane sulfonate) tin (II), tin sulfate (II), tin oxide (II), tin oxide (IV), tin sulfide (II), tin sulfide (IV), oxidation Dimethyltin (IV), methylphenyltin (IV) oxide, dibuty oxide Tin (IV), dioctyl tin (IV) oxide, diphenyl tin (IV) oxide, tributyl tin oxide, triethyl tin hydroxide (IV), triphenyl tin hydroxide (IV), tributyl tin hydride, monobutyl tin (IV) Oxide, tetramethyltin (IV), tetraethyltin (IV), tetrabutyltin (IV), dibutyldiphenyltin (IV), tetraphenyltin (IV), tributyltin (IV) acetate, triisobutyltin (IV) acetate, Triphenyltin acetate (IV), dibutyltin diacetate, dibutyltin dioctanoate, dibutyltin (IV) dilaurate, dibutyltin (IV) maleate, dibutyltin bis (acetylacetonate), tributyltin chloride (IV), Dibutyltin dichloride, monobutyltin trichloride, dioctyltin dichloride, triphenyltin (IV) chloride, sulfide Butyltin, tributyltin sulfate, tin (II) methanesulfonate, tin (II) ethanesulfonate, tin (II) trifluoromethanesulfonate, ammonium hexachlorotin (IV), dibutyltin sulfide, diphenyltin sulfide and triethyl sulfate Examples thereof include tin compounds such as tin and phthalocyanine tin (II). Also, titanium methoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, titanium isobutoxide, titanium cyclohexyl, titanium phenoxide, titanium chloride, titanium diacetate, titanium triacetate, titanium tetraacetate, titanium (IV) oxide, etc. Titanium compounds, lead diisopropoxy (II), lead monochloride, lead acetate, lead (II) octylate, lead (II) isooctanoate, lead (II) isononanoate, lead (II) laurate, lead oleate (II), lead compounds such as lead (II) linoleate, lead naphthenate, lead (II) neodecanoate, lead oxide, lead (II) sulfate, zinc powder, methyl propoxy zinc, zinc chloride, zinc acetate, octylic acid Zinc (II), zinc naphthenate, zinc carbonate, zinc oxide, zinc sulfate and other zinc compounds, chloride Baltic, cobalt acetate, cobalt (II) octylate, cobalt (II) isooctanoate, cobalt (II) isononanoate, cobalt (II) laurate, cobalt (II) oleate, cobalt (II) linoleate, cobalt naphthenate , Cobalt compounds such as cobalt (II) neodecanoate, cobaltous carbonate, cobaltous sulfate, cobalt (II) oxide, iron (II) chloride, iron (II) acetate, iron (II) octylate, iron naphthenate Iron compounds such as iron carbonate (II), iron sulfate (II), iron oxide (II), propoxy lithium, lithium chloride, lithium acetate, lithium octylate, lithium naphthenate, lithium carbonate, dilithium sulfate, lithium oxide, etc. Lithium compounds, triisopropoxy europium (III), triisopropoxy neo (III), triisopropoxylantan, triisopropoxy samarium (III), triisopropoxy yttrium, isopropoxy yttrium, dysprosium chloride, europium chloride, lanthanum chloride, neodymium chloride, samarium chloride, yttrium chloride, dysprosium triacetate (III ), Europium triacetate (III), lanthanum acetate, neodymium triacetate, samarium acetate, yttrium triacetate, dysprosium carbonate (III), dysprosium carbonate (IV), europium carbonate (II), lanthanum carbonate, neodymium carbonate, samarium carbonate ( II), samarium carbonate (III), yttrium carbonate, dysprosium sulfate, europium (II) sulfate, lanthanum sulfate, neodymium sulfate, samarium sulfate, yttrium sulfate, yttrium dioxide Examples include rare earth compounds such as europium, lanthanum oxide, neodymium oxide, samarium (III) oxide, and yttrium oxide. In addition, potassium isopropoxide, potassium chloride, potassium acetate, potassium octylate, potassium naphthenate, potassium compounds such as t-butyl potassium carbonate, potassium sulfate, potassium oxide, copper (II) diisopropoxide, copper chloride (II), copper acetate (II), copper octylate, copper naphthenate, copper sulfate (II), copper compounds such as dicopper carbonate, nickel chloride, nickel acetate, nickel octylate, nickel carbonate, nickel sulfate (II) , Nickel compounds such as nickel oxide, tetraisopropoxyzirconium (IV), zirconium trichloride, zirconium acetate, zirconium octylate, zirconium naphthenate, zirconium carbonate (II), zirconium carbonate (IV), zirconium sulfate, zirconium oxide (II Zirconium compounds such as Antimony compounds such as lysopropoxyantimony, antimony fluoride (III), antimony fluoride (V), antimony acetate, antimony (III) oxide, magnesium, magnesium diisopropoxide, magnesium chloride, magnesium acetate, magnesium lactate, carbonic acid Magnesium compounds such as magnesium, magnesium sulfate, magnesium oxide, diisopropoxy calcium, calcium chloride, calcium acetate, calcium octylate, calcium naphthenate, calcium lactate, calcium sulfate, etc., aluminum, aluminum isopropoxide, aluminum chloride , Aluminum acetate, aluminum octylate, aluminum sulfate, aluminum oxide and other aluminum compounds, germanium, tetraisopropyl Germanium compounds such as xygermane, germanium oxide (IV), triisopropoxy manganese (III), manganese trichloride, manganese acetate, manganese octylate (II), manganese naphthenate (II), manganese compounds such as manganese sulfate, Examples thereof include bismuth chloride (III), bismuth powder, bismuth oxide (III), bismuth acetate, bismuth octylate, bismuth neodecanoate, and the like. Also, sodium stannate, magnesium stannate, potassium stannate, calcium stannate, manganese stannate, bismuth stannate, barium stannate, strontium stannate, sodium titanate, magnesium titanate, aluminum titanate, potassium titanate, Also preferred are compounds composed of two or more metal elements such as calcium titanate, cobalt titanate, zinc titanate, manganese titanate, zirconium titanate, bismuth titanate, barium titanate, strontium titanate.

The acid catalyst may be a Bronsted acid as a proton donor, a Lewis acid as an electron pair acceptor, or an organic acid or an inorganic acid. Specifically, monocarboxylic acid compounds such as formic acid, acetic acid, propionic acid, heptanoic acid, octanoic acid, octylic acid, nonanoic acid, isononanoic acid, trifluoroacetic acid and trichloroacetic acid, oxalic acid, succinic acid, maleic acid, tartaric acid And dicarboxylic acid compounds such as malonic acid, tricarboxylic acid compounds such as citric acid and tricarivallic acid, benzenesulfonic acid, n-butylbenzenesulfonic acid, n-octylbenzenesulfonic acid, n-dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid 2,5-dimethylbenzenesulfonic acid, 2,5-dibutylbenzenesulfonic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, 3-amino-4-hydroxybenzenesulfonic acid , 5-amino-2 Methylbenzenesulfonic acid, 3,5-diamino-2,4,6-trimethylbenzenesulfonic acid, 2,4-dinitrobenzenesulfonic acid, p-chlorobenzenesulfonic acid, 2,5-dichlorobenzenesulfonic acid, p-phenol Sulfonic acid, cumene sulfonic acid, xylene sulfonic acid, o-cresol sulfonic acid, m-cresol sulfonic acid, p-cresol sulfonic acid, p-toluene sulfonic acid, 2-naphthalene sulfonic acid, 1-naphthalene sulfonic acid, isopropyl naphthalene sulfone Acid, dodecylnaphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, 1,5-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, 4,4-biphenyldisulfonic acid, anthraquinone-2-sulfonic acid, m- Benzene disulfonic acid, 2,5-diamino-1,3-benzenedisulfonic acid, aniline-2,4-disulfonic acid, anthraquinone-1,5-disulfonic acid, aromatic sulfonic acid such as polystyrene sulfonic acid, methanesulfonic acid, Ethanesulfonic acid, 1-propanesulfonic acid, n-octylsulfonic acid, pentadecylsulfonic acid, trifluoromethanesulfonic acid, trichloromethanesulfonic acid, 1,2-ethanedisulfonic acid, 1,3-propanedisulfonic acid, aminomethanesulfone Acids, aliphatic sulfonic acids such as 2-aminoethanesulfonic acid, sulfonic acid compounds such as cyclopentanesulfonic acid, cyclohexanesulfonic acid and camphorsulfonic acid, alicyclic sulfonic acids such as 3-cyclohexylaminopropanesulfonic acid, aspartic acid And Acidic amino acids such as glutamic acid, phosphoric acid monoesters such as ascorbic acid, retinoic acid, phosphoric acid, metaphosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, monododecyl phosphate and monooctadecyl phosphate, didodecyl phosphate And phosphoric acid diesters such as dioctadecyl phosphate, phosphoric acid compounds such as phosphorous acid monoester and phosphite diester, boric acid, hydrochloric acid, sulfuric acid and the like. Further, the shape of the acid catalyst is not particularly limited, and any of a solid acid catalyst and a liquid acid catalyst may be used. For example, as the solid acid catalyst, acidic clay, kaolinite, bentonite, montmorillonite, talc, zirconium silicate and Natural minerals such as zeolite, oxides such as silica, alumina, titania and zirconia or oxide composites such as silica alumina, silica magnesia, silica boria, alumina boria, silica titania and silica zirconia, chlorinated alumina, fluorinated alumina, positive Examples thereof include ion exchange resins.

In the present invention, when considering the molecular weight of polylactic acid produced by the ring-opening polymerization method, a metal catalyst is preferable as the polymerization catalyst of the ring-opening polymerization method, among which a tin compound, a titanium compound, an antimony compound, and a rare earth compound are more preferable. In consideration of the melting point of polylactic acid produced by the ring-opening polymerization method, tin compounds and titanium compounds are more preferable. Furthermore, in consideration of the thermal stability of polylactic acid produced by the ring-opening polymerization method, a tin-based organic carboxylate or a tin-based halogen compound is preferable, and in particular, tin (II) acetate, tin (II) octylate, And tin (II) chloride is more preferred.

The addition amount of the polymerization catalyst in the ring-opening polymerization method is preferably 0.001 part by weight or more and 2 parts by weight or less with respect to 100 parts by weight of the raw material to be used (L-lactic acid, D-lactic acid, etc.). More preferred is 1 part by weight or more. When the catalyst amount is within the above preferred range, the effect of shortening the polymerization time can be obtained, while the molecular weight of the finally obtained polylactic acid block copolymer tends to increase. Moreover, when using 2 or more types of catalysts together, it is preferable that a total addition amount exists in said range.

Regarding the addition timing of the polymerization catalyst in the ring-opening polymerization method, it is preferable to add the catalyst after heating and dissolving the lactide from the viewpoint of uniformly dispersing the catalyst in the system and increasing the polymerization activity.

Next, a method for preparing a polylactic acid block copolymer by solid phase polymerization after mixing poly-L-lactic acid and poly-D-lactic acid (Preparation Method 2) will be described. For the polymerization of poly-L-lactic acid and poly-D-lactic acid in this preparation method, any of a ring-opening polymerization method and a direct polymerization method can be used.

When a polylactic acid block copolymer is prepared by solid phase polymerization after mixing poly-L-lactic acid and poly-D-lactic acid, the weight average molecular weight and stereocomplex formation rate after solid phase polymerization are increased. One of poly-L-lactic acid and poly-D-lactic acid has a weight average molecular weight of 60,000 to 300,000 or less, and the other has a weight average molecular weight of 10,000 to 100,000 or less. It is preferable. More preferably, one weight average molecular weight is 100,000 to 270,000 and the other weight average molecular weight is 15,000 to 80,000. Particularly preferably, one weight average molecular weight is 150,000 to 240,000 and the other weight average molecular weight is 20,000 to 50,000. The combination of the weight average molecular weights of poly-L-lactic acid and poly-D-lactic acid is preferably selected as appropriate so that the weight average molecular weight after mixing is 90,000 or more.

Further, in the present invention, the weight average molecular weight of the poly-L-lactic acid component and the poly-D-lactic acid component is such that the weight average molecular weight of either one of poly-L-lactic acid or poly-D-lactic acid is 120,000 or more. It is also a preferred embodiment that the weight average molecular weight is 300,000 or less and the other weight average molecular weight is 30,000 or more and 100,000 or less. More preferably, one weight average molecular weight is 100,000 or more and 270,000 or less, and the other weight average molecular weight is 35,000 or more and 80,000 or less. More preferably, it is 125,000 or more and 255,000 or less, and the other weight average molecular weight is 25,000 or more and 50,000 or less.

In the poly-L-lactic acid and poly-D-lactic acid used in the present invention, the ratio of the higher weight average molecular weight to the lower weight average molecular weight is preferably 2 or more and less than 30. More preferably, it is 3 or more and less than 20, and most preferably 5 or more and less than 15. The combination of the weight average molecular weights of poly-L-lactic acid and poly-D-lactic acid is preferably selected as appropriate so that the weight average molecular weight after mixing is 90,000 or more.

The poly-L-lactic acid and poly-D-lactic acid used in the present invention have a weight average molecular weight of each of the poly-L-lactic acid component and the poly-D-lactic acid component within the above range, It is preferable that both the ratio of the weight average molecular weight of the L-lactic acid component and the poly-D-lactic acid component is 2 or more and less than 30.

Here, the weight average molecular weight is a value in terms of standard polymethyl methacrylate as measured by gel permeation chromatography (GPC) using hexafluoroisopropanol or chloroform as a solvent.

The amount of lactide and oligomer contained in poly-L-lactic acid or poly-D-lactic acid is preferably 5% or less, respectively. More preferably, it is 3% or less, and particularly preferably 1% or less. The amount of lactic acid contained in poly-L-lactic acid or poly-D-lactic acid is preferably 2% or less. More preferably, it is 1% or less, and particularly preferably 0.5% or less.

The acid value of poly-L-lactic acid or poly-D-lactic acid to be mixed is preferably 100 eq / ton or less for either one of poly-L-lactic acid or poly-D-lactic acid. More preferably, it is 50 eq / ton or less, More preferably, it is 30 eq / ton or less, Most preferably, it is 15 eq / ton or less. The other acid value of the poly-L-lactic acid or poly-D-lactic acid to be mixed is preferably 600 eq / ton or less. More preferably, it is 300 eq / ton or less, More preferably, it is 150 eq / ton or less, Especially preferably, it is 100 eq / ton or less.

Regarding the method of polymerizing poly-L-lactic acid or poly-D-lactic acid using the ring-opening polymerization method, the water content in the reaction system is the sum of L-lactide and D-lactide from the viewpoint of obtaining a high molecular weight product. It is preferable that it is 4 mol% or less with respect to quantity. More preferably, it is 2 mol% or less, and 0.5 mol% or less is particularly preferable. The water content is a value measured by a coulometric titration method using the Karl Fischer method.

As the polymerization catalyst for polymerizing poly-L-lactic acid or poly-D-lactic acid by the ring-opening polymerization method, the same metal catalyst and acid catalyst as in Preparation Method 1 can be mentioned.

Further, the addition amount of the polymerization catalyst in the ring-opening polymerization method is preferably 0.001 part by weight or more and 2 parts by weight or less with respect to 100 parts by weight of the raw material used (L-lactic acid, D-lactic acid, etc.). More preferred is 0.001 part by weight or more and 1 part by weight or less. When the catalyst amount is within the above preferred range, the effect of shortening the polymerization time can be obtained, while the molecular weight of the finally obtained polylactic acid block copolymer tends to increase. Moreover, when using 2 or more types of catalysts together, it is preferable that a total addition amount exists in said range.

Also, examples of the polymerization catalyst for polymerizing poly-L-lactic acid or poly-D-lactic acid by using a direct polymerization method include metal catalysts and acid catalysts. Examples of the metal catalyst include tin catalysts, titanium compounds, lead compounds, zinc compounds, cobalt compounds, iron compounds, lithium compounds, and rare earth compounds. As the kind of the compound, metal alkoxide, metal halogen compound, organic carboxylate, carbonate, sulfate, oxide and the like are preferable. Specifically, the metal compound described in the preparation method 1 as a metal catalyst, and the acid compound described in the preparation method 1 as an acid catalyst are mentioned.

When considering the molecular weight of polylactic acid produced using a direct polymerization method, tin compounds, titanium compounds, antimony compounds, rare earth compounds, and acid catalysts are preferred, and when considering the melting point of the produced polylactic acid, Tin compounds, titanium compounds, and sulfonic acid compounds are more preferred. Furthermore, in consideration of the thermal stability of the polylactic acid produced, in the case of a metal catalyst, a tin-based organic carboxylate or a tin-based halogen compound is preferable, and in particular, tin (II) acetate, tin octylate (II ), And tin (II) chloride, and in the case of acid catalysts, mono and disulfonic acid compounds are preferred, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, propanedisulfonic acid, naphthalene disulfonic acid, and 2-amino More preferred is ethanesulfonic acid. In addition, one type of catalyst may be used, or two or more types may be used in combination. However, in view of increasing the polymerization activity, it is preferable to use two or more types in combination, and it is possible to suppress coloring. In addition, it is preferable to use one or more selected from tin compounds and / or one or more selected from sulfonic acid compounds. Further, in terms of excellent productivity, tin (II) acetate and / or tin octylate ( II) and methanesulfonic acid, ethanesulfonic acid, propanedisulfonic acid, naphthalene disulfonic acid and 2-aminoethanesulfonic acid are more preferably used in combination. Tin (II) acetate and / or tin octylate (II) combined with any one of methanesulfonic acid, ethanesulfonic acid, propanedisulfonic acid, and 2-aminoethanesulfonic acid But more preferable.

The addition amount of the polymerization catalyst is preferably 0.001 part by weight or more and 2 parts by weight or less with respect to 100 parts by weight of the raw material to be used (L-lactic acid, D-lactic acid, etc.). More preferred are parts by weight or less. When the catalyst amount is within this preferred range, the effect of shortening the polymerization time can be obtained, while the molecular weight of the finally obtained polylactic acid block copolymer can be sufficiently increased. When two or more types of catalysts are used in combination, the total addition amount is preferably within the above range, and one or more types selected from tin compounds and / or one or more types selected from sulfonic acid compounds are used in combination. In that case, it is preferable that the weight ratio of the tin compound and the sulfonic acid compound is 1: 1 to 1:30 in that the high polymerization activity can be maintained and coloring can be suppressed. It is more preferable that the ratio is 1: 2 to 1:15.

Regarding the addition timing of the polymerization catalyst, particularly when polylactic acid is polymerized by the direct polymerization method, it is preferable that the acid catalyst is added before the raw material or the raw material is dehydrated in terms of excellent productivity. The addition of the raw material after dehydration is preferable from the viewpoint of increasing the polymerization activity.

In the present invention, when poly-L-lactic acid and poly-D-lactic acid are mixed and the mixture is solid-phase polymerized to obtain a polylactic acid block copolymer, the mixture of poly-L-lactic acid and poly-D-lactic acid is mixed. Therefore, the stereocomplex formation rate (Sc) is preferably in the range exceeding 60% immediately before the solid phase polymerization. More preferably, it is in the range of 70 to 99%, and particularly preferably in the range of 80 to 95%. That is, based on the above formula (4), the stereo complex formation rate (Sc) preferably satisfies the following formula (2).

Sc = ΔHh / (ΔHl + ΔHh) × 100> 60 (2)
here,
ΔHh: calorific value (J / g) based on stereocomplex crystals when the temperature is raised at a rate of temperature rise of 20 ° C./min in DSC measurement of a mixture of poly-L-lactic acid and poly-D-lactic acid
ΔHl: Crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal when heated at a rate of temperature increase of 20 ° C./min in DSC measurement of a mixture of poly-L-lactic acid and poly-D-lactic acid Heat quantity based on (J / g)
In addition, the presence or absence of crystallization of poly-L-lactic acid and poly-D-lactic acid used for mixing is not particularly limited, and the crystallized poly-L-lactic acid and poly-D-lactic acid may be mixed. Alternatively, molten poly-L-lactic acid and poly-D-lactic acid can be mixed. In the case of crystallization of poly-L-lactic acid and poly-D-lactic acid used for mixing, as a specific method, a method of holding at a crystallization temperature in a gas phase or a liquid phase and a poly-L in a molten state A method of retaining lactic acid and poly-D-lactic acid in a melting machine having a melting point of −50 ° C. to a melting point of + 20 ° C. while applying shear, and melting poly-L-lactic acid and poly-D-lactic acid with a melting point of −50 ° C. For example, a method of staying while applying pressure in a melting point + 20 ° C. melting machine may be used.

The crystallization treatment temperature here is higher than the glass transition temperature and is lower than the melting point of polylactic acid having a low melting point among the poly-L-lactic acid or poly-D-lactic acid mixed above. Although not particularly limited, it is more preferable that the temperature is within the range of the temperature rising crystallization temperature and the temperature falling crystallization temperature measured in advance by a differential scanning calorimeter (DSC).

When crystallization is performed in the gas phase or in the liquid phase, any condition of reduced pressure, normal pressure or increased pressure may be used.

In addition, the time for crystallization in the gas phase or liquid phase is not particularly limited, but it is sufficiently crystallized within 3 hours, and preferably within 2 hours.

In the above-described method for crystallizing poly-L-lactic acid and poly-D-lactic acid by applying shear or pressure in the melting machine, the melting machine is not limited as long as it can apply shear or pressure, and the polymerization can , A kneader, a Banbury mixer, a single screw extruder, a twin screw extruder, an injection molding machine, etc. can be used, and a single screw extruder and a twin screw extruder are preferred.

In the method of crystallizing by applying shear or pressure in the melting machine, the crystallization temperature is from −50 ° C. to melting point + 20 ° C. relative to the melting point of poly-L-lactic acid and poly-D-lactic acid to be mixed. A range is preferred. A more preferable range of the crystallization temperature is a melting point of −40 ° C. to a melting point, and a particularly preferable temperature range is a melting point of −30 ° C. to a melting point of −5 ° C. The temperature of the melting machine is usually set to a melting point + 20 ° C. or higher so that the resin melts and exhibits good fluidity. If the temperature of the melting machine is within the above preferred range, the crystallizing while maintaining appropriate fluidity. On the other hand, the generated crystals are difficult to remelt. Here, the melting point is the crystal melting temperature when the temperature is raised from 30 ° C. to 250 ° C. at a rate of temperature rise of 20 ° C./min using differential thermal scanning measurement.

The crystallization treatment time is preferably 0.1 to 10 minutes, more preferably 0.3 to 5 minutes, and particularly preferably 0.5 to 3 minutes. When the crystallization treatment time is within the above preferred range, crystallization occurs sufficiently, while thermal decomposition hardly occurs.

By applying shear in the melting machine, the molecules of the molten resin tend to be oriented, and as a result, the crystallization speed can be remarkably increased. The shear rate at this time is preferably in the range of 10 to 400 (/ second). When the shear rate is within the above preferred range, the crystallization rate becomes sufficiently high, while thermal decomposition due to shear heat generation hardly occurs.

Even when pressure is applied, crystallization tends to be promoted, and crystallized polylactic acid having both good fluidity and crystallinity can be obtained particularly in the range of 0.05 to 10 (MPa). preferable. When the pressure is within the above preferred range, the crystallization rate becomes sufficiently large.

Further, it is particularly preferable to perform treatment by simultaneously applying a shearing rate of 10 to 400 (/ sec) and a pressure of 0.05 to 10 (MPa) because the crystallization rate becomes higher.

The mixing method of poly-L-lactic acid and poly-D-lactic acid is not particularly limited, and for example, the melting end temperature of the component having the higher melting point among poly-L-lactic acid and poly-D-lactic acid. The method of melt kneading, the method of removing the solvent after mixing in the solvent, or at least one of the molten poly-L-lactic acid and poly-D-lactic acid is a temperature range from -50 ° C to 20 ° C in advance. And a method of mixing so that crystals of a mixture composed of poly-L-lactic acid and poly-D-lactic acid remain after being retained while applying shear in a melting machine.

Here, the melting point refers to the temperature at the peak top of the polylactic acid single crystal melting peak measured by (DSC) with a differential scanning calorimeter, and the melting end temperature is determined with a differential scanning calorimeter (DSC). It means the peak end temperature in the polylactic acid single crystal melting peak measured by the above.

Examples of the method of melt-kneading at a temperature higher than the melting end temperature include a method of mixing poly-L-lactic acid and poly-D-lactic acid by a batch method or a continuous method. Examples thereof include a single screw extruder, a twin screw extruder, a plast mill, a kneader, and a stirred tank reactor equipped with a decompression device. In terms of uniform and sufficient kneading, a single screw extruder or a twin screw extruder may be used. preferable.

Regarding the temperature condition at the time of melting and kneading at a temperature higher than the melting end temperature, it is preferable to carry out at a temperature higher than the melting end temperature of the higher melting point component of poly-L-lactic acid and poly-D-lactic acid. The range is preferably 140 ° C to 250 ° C, more preferably 160 ° C to 230 ° C, and particularly preferably 180 ° C to 210 ° C. When the mixing temperature is within the above-mentioned preferable range, mixing can be performed in a molten state, and the molecular weight of the mixture is hardly lowered during mixing. Furthermore, the fluidity of the mixture can be kept constant, and a significant decrease in fluidity hardly occurs.

The mixing time condition is preferably in the range of 0.1 minute to 10 minutes, more preferably in the range of 0.3 minute to 5 minutes, and particularly preferably in the range of 0.5 minute to 3 minutes. When the mixing time is in the above preferred range, poly-L-lactic acid and poly-D-lactic acid can be uniformly mixed, while thermal decomposition due to mixing hardly occurs.

The pressure condition for mixing at the melting end temperature or higher is not particularly limited, and may be any condition under an air atmosphere or an inert gas atmosphere such as nitrogen.

A specific method for mixing poly-L-lactic acid and poly-D-lactic acid crystallized by applying shear or pressure in a melting machine includes a batch method or a continuous method. The melted poly-L-lactic acid and poly-D-lactic acid may be mixed into the melting point of polylactic acid having a lower melting point of poly-L-lactic acid and poly-D-lactic acid. A method of staying while applying shear in a melting machine of −50 ° C. to melting point + 20 ° C., or a poly-L-lactic acid and poly-D-lactic acid in a molten state are mixed with poly-L-lactic acid and poly-D-lactic acid. Of the polylactic acid having a lower melting point, the mixture of poly-L-lactic acid and poly-D-lactic acid is mixed by a method of staying while applying pressure in a melting machine having a melting point of −50 ° C. to melting point + 20 ° C. Stereo complex formation rate (Sc) It can be controlled. The stereo complex formation rate (Sc) can be calculated by the above formula (4).

The mixing temperature condition is preferably in the range of -50 ° C. to melting point + 20 ° C. with respect to the melting point of the mixture of poly-L-lactic acid and poly-D-lactic acid. A more preferable range of the mixing temperature is a melting point of −40 ° C. to a melting point, and a particularly preferable range is a melting point of −30 ° C. to a melting point of −5 ° C. The temperature of the melting machine is usually preferably set to a melting point + 20 ° C. or higher in order for the resin to melt and express good fluidity, but with such a preferred mixing temperature, the fluidity does not decrease too much, On the other hand, the generated crystals are difficult to remelt. Here, the melting point refers to the crystal melting temperature when the temperature is raised from 30 ° C. to 250 ° C. at a rate of temperature rise of 20 ° C./min using a differential scanning calorimeter (DSC).

The shear rate when mixing poly-L-lactic acid and poly-D-lactic acid crystallized by applying shear or pressure in the melting machine is preferably in the range of 10 to 400 (/ sec). When the shear rate is in the above preferred range, poly-L-lactic acid and poly-D-lactic acid can be uniformly mixed while maintaining fluidity and crystallinity, while heat is generated by shearing heat generated during mixing. It is difficult to cause decomposition.

The pressure applied during mixing is preferably in the range of 0.05 to 10 (MPa). When the pressure is in the above preferred range, poly-L-lactic acid and poly-D-lactic acid can be uniformly mixed while maintaining fluidity and crystallinity.

In kneading using an extruder, the method of supplying polylactic acid is not particularly limited, and a method of supplying poly-L-lactic acid and poly-D-lactic acid from a resin supply port in a lump or side supply as required. A method of supplying poly-L-lactic acid and poly-D-lactic acid separately to the resin supply port and the side supply port by using the mouth is possible. The supply of polylactic acid to the kneader can also be performed in a molten state directly from the polylactic acid production process.

The screw element in the extruder is preferably provided with a kneading element in the mixing part so that poly-L-lactic acid and poly-D-lactic acid can be uniformly mixed to form a stereo complex.

In the mixing step, the mixing weight ratio of poly-L-lactic acid composed of L-lactic acid units and poly-D-lactic acid composed of D-lactic acid units is preferably 90:10 to 10:90. More preferably, it is 80:20 to 20:80, and particularly preferably 75:25 to 60:40 or 40:60 to 25:75. When the total weight ratio of the segment consisting of the L-lactic acid unit and the segment consisting of the D-lactic acid unit is within the above preferred range, a polylactic acid stereocomplex can be easily formed. As a result, a polylactic acid block copolymer is formed. The rise in the melting point of is sufficiently large. When the mixing weight ratio of poly-L-lactic acid and poly-D-lactic acid is other than 50:50, a larger amount of poly-L-lactic acid or poly-D-lactic acid having a larger weight average molecular weight may be blended. preferable.

In this mixing step, it is preferable to contain a catalyst in the mixture in order to efficiently advance the next solid phase polymerization. At this time, the catalyst may be a residual amount of the catalyst in producing poly-L-lactic acid and / or poly-D-lactic acid, or one or more selected from the above catalysts may be added in the mixing step. it can.

The content of the catalyst for efficiently proceeding with the solid-phase polymerization is preferably 0.001 part by weight or more and 1 part by weight or less with respect to 100 parts by weight of the mixture of poly-L-lactic acid and poly-D-lactic acid. More preferred is 0.001 part by weight or more and 0.5 part by weight or less. When the catalyst amount is within the above preferred range, the effect of shortening the reaction time of solid phase polymerization can be obtained, while the molecular weight of the finally obtained polylactic acid block copolymer tends to increase.

The weight average molecular weight (Mw) of the mixture of poly-L-lactic acid and poly-D-lactic acid after mixing is preferably 90,000 or more and less than 300,000 from the viewpoint of mechanical properties of the mixture. More preferably, it is 120,000 or more and less than 300,000, and it is especially preferable that it is 140,000 or more and less than 300,000.

Further, the degree of dispersion of the mixture of poly-L-lactic acid and poly-D-lactic acid after mixing is preferably in the range of 1.5 to 4.0. A more preferred range is 2.0 to 3.7, and a particularly preferred range is 2.5 to 3.5. Here, the degree of dispersion means the ratio of the weight average molecular weight to the number average molecular weight of the mixture. Specifically, the standard polydispersity by gel permeation chromatography (GPC) measurement using hexafluoroisopropanol or chloroform as a solvent. It is a value in terms of methyl methacrylate.

When the mixture is subjected to solid phase polymerization, the shape of the mixture of poly-L-lactic acid and poly-D-lactic acid is not particularly limited and may be any of agglomerates, films, pellets, and powders. From the viewpoint of efficiently proceeding the polymerization, it is preferable to use pellets or powder. Examples of the method of pelletizing a mixture of poly-L-lactic acid and poly-D-lactic acid include a method of extruding the mixture into a strand and pelletizing, and a method of extruding the mixture into water and pelletizing with an underwater cutter. It is done. In addition, examples of a method for making a mixture of poly-L-lactic acid and poly-D-lactic acid into powder include a method of pulverizing using a pulverizer such as a mixer, blender, ball mill, and hammer mill. The method for carrying out this solid phase polymerization step is not particularly limited, and may be a batch method or a continuous method. The reaction vessel may be a stirred tank reactor, a mixer reactor, a tower reactor, or the like. These reactors can be used in combination of two or more.

When performing this solid phase polymerization step, it is preferable that a mixture of poly-L-lactic acid and poly-D-lactic acid is crystallized. In the present invention, when the mixture obtained in the mixing step of poly-L-lactic acid and poly-D-lactic acid is in a crystallized state, the poly-L-lactic acid and poly-D are used in the solid phase polymerization step. -Crystallization of the mixture of lactic acid is not necessarily required, but the efficiency of solid phase polymerization can be further increased by crystallization.

The method for crystallization is not particularly limited, and a known method can be used. For example, a method of holding at a crystallization treatment temperature in a gas phase or a liquid phase, or a method of cooling and solidifying a molten mixture of poly-L-lactic acid and poly-D-lactic acid while performing stretching or shearing operations. From the viewpoint that the operation is simple, a method of holding at the crystallization temperature in the gas phase or in the liquid phase is preferable.

The crystallization treatment temperature here is particularly limited as long as it is higher than the glass transition temperature and lower than the melting point of polylactic acid having a low melting point among the mixed poly-L-lactic acid and poly-D-lactic acid. Although it is not performed, it is more preferable that the temperature is within the range of the temperature-rise crystallization temperature and the temperature-fall crystallization temperature measured in advance by a differential scanning calorimeter (DSC).

When crystallization is performed, any of reduced pressure, normal pressure, and increased pressure may be used.

Further, the time for crystallization is not particularly limited, but it is sufficiently crystallized within 3 hours, and within 2 hours is preferable.

The temperature condition for carrying out this solid phase polymerization step is preferably a temperature not higher than the melting point of the mixture of poly-L-lactic acid and poly-D-lactic acid. The mixture of poly-L-lactic acid and poly-D-lactic acid has a melting point based on stereocomplex crystals in the range of 190 ° C. to 230 ° C. due to stereocomplex formation, and also has a poly-L in the range of 150 ° C. to 185 ° C. Since it has melting points based on -lactic acid single crystals and poly-D-lactic acid single crystals, it is preferable to carry out solid phase polymerization below these melting points. Specifically, it is preferably 100 ° C. or higher and 220 ° C. or lower, and more preferably 110 ° C. or higher and 200 ° C. or lower, more preferably 120 ° C. or higher and 180 ° C. or lower, from the viewpoint of efficiently proceeding solid phase polymerization. Is more preferable, and it is particularly preferably 130 ° C. or higher and 170 ° C. or lower.

In order to shorten the reaction time of solid phase polymerization, it is preferable to raise the temperature stepwise or continuously as the reaction proceeds. The temperature conditions when the temperature is raised stepwise during the solid phase polymerization are as follows. The first stage is 120 ° C. to 145 ° C. for 1 to 15 hours, the second stage is 135 ° C. to 160 ° C. for 1 to 15 hours, and the third stage It is preferable that the temperature is raised from 150 ° C. to 175 ° C. for 10 to 30 hours, further, the first stage is from 130 ° C. to 145 ° C. for 2 to 12 hours, and the second stage is from 140 ° C. to 160 ° C. for 2 to 12 hours. In the third stage, it is more preferable to raise the temperature at 155 ° C. to 175 ° C. for 10 to 25 hours. The temperature condition for continuous temperature increase during solid-phase polymerization is that the temperature is continuously increased from 150 ° C. to 175 ° C. at a rate of 1 to 5 (° C./min) from the initial temperature of 130 ° C. to 150 ° C. Is preferred. Further, combining stepwise temperature rise and continuous temperature rise is also preferable from the viewpoint of efficiently proceeding with solid phase polymerization.

Further, when this solid phase polymerization step is carried out, it is preferably carried out under a vacuum or an inert gas stream such as dry nitrogen. The degree of vacuum when performing solid-phase polymerization under vacuum is preferably 150 Pa or less, more preferably 75 Pa or less, and particularly preferably 20 Pa or less. The flow rate when solid-phase polymerization is performed under an inert gas stream is preferably in the range of 0.1 to 2,000 (mL / min), and 0.5 to 1,000 (mL / min) with respect to 1 g of the mixture. Is more preferable, and a range of 1.0 to 500 (mL / min) is particularly preferable.

The yield (Y) of the polymer after solid phase polymerization is preferably 90% or more. More preferably, it is 93% or more, and particularly preferably 95% or more. The polymer yield (Y) here is the ratio of the weight of the polylactic acid block copolymer after solid phase polymerization to the weight of the mixture before solid phase polymerization. Specifically, when the weight of the mixture before solid phase polymerization is Wp and the weight of the polymer after solid phase polymerization is Ws, the yield (Y) of the polymer can be calculated by the following formula (7).

Y = Ws / Wp × 100 (7)
In the solid phase polymerization step, it is preferable that the degree of dispersion of the mixture is small. Specifically, the dispersion degree of the mixture before the solid phase polymerization is in the range of 1.5 to 4.0, and the dispersion degree of the polylactic acid block copolymer is in the range of 1.5 to 2.7 after the solid phase polymerization. It is preferable to become. More preferably, the dispersion degree of the mixture before the solid phase polymerization is in the range of 2.0 to 3.7, and the dispersion degree of the polylactic acid block copolymer is reduced to the range of 1.8 to 2.6 after the solid phase polymerization. Particularly preferably, the dispersion degree of the polylactic acid block copolymer is 2.0 to 2.5 after the solid phase polymerization from the range of the dispersion degree of the mixture 2.5 to 3.5 before the solid phase polymerization. It is to be in the range.

Next, poly-L-lactic acid and poly-D-lactic acid are melt kneaded for a long time at a temperature equal to or higher than the melting end temperature of the component having the higher melting point, so that the L-lactic acid unit segment and the D-lactic acid unit segment A method (Preparation Method 3) for obtaining a polylactic acid block copolymer obtained by transesterifying the lactic acid block copolymer will be described. Also in this preparation method, for the polymerization of poly-L-lactic acid and poly-D-lactic acid, any of the above-described ring-opening polymerization method and direct polymerization method can be used.

In order to obtain a polylactic acid block copolymer by this method, the weight average molecular weight of either one of poly-L-lactic acid and poly-D-lactic acid is high in that the stereocomplex formation rate becomes high after melt-kneading. Preferably, the weight average molecular weight is 60,000 to 300,000 or less, and the other weight average molecular weight is 10,000 to 100,000 or less. More preferably, one weight average molecular weight is 100,000 to 270,000 and the other weight average molecular weight is 15,000 to 80,000. Particularly preferably, one weight average molecular weight is 150,000 to 240,000 and the other weight average molecular weight is 20,000 to 50,000. The combination of the weight average molecular weights of poly-L-lactic acid and poly-D-lactic acid is preferably selected as appropriate so that the weight average molecular weight after mixing is 90,000 or more.
Further, in the present invention, the weight average molecular weight of the poly-L-lactic acid component and the poly-D-lactic acid component is such that the weight average molecular weight of either poly-L-lactic acid or poly-D-lactic acid is 60,000 or more. It is also a preferred embodiment that the weight average molecular weight is 300,000 or less and the other weight average molecular weight is 30,000 or more and 100,000 or less. More preferably, one weight average molecular weight is 100,000 or more and 270,000 or less, and the other weight average molecular weight is 20,000 or more and 80,000 or less. More preferably, it is 125,000 or more and 255,000 or less, and the other weight average molecular weight is 25,000 or more and 50,000 or less.

As a method of melt kneading for a long time at a temperature higher than the melting end temperature, a method of mixing poly-L-lactic acid and poly-D-lactic acid by a batch method or a continuous method may be mentioned, and any method may be used. Examples of the kneading apparatus include a single screw extruder, a twin screw extruder, a plast mill, a kneader, and a stirred tank reactor equipped with a pressure reducing device. From the viewpoint of uniform and sufficient kneading, a single screw extruder and a twin screw extruder are used. It is preferable to use it.

Regarding the mixing temperature condition, it is important that the mixing is performed at a temperature higher than the melting end temperature of the component having a higher melting point among poly-L-lactic acid and poly-D-lactic acid. The range is preferably 140 ° C. to 280 ° C., more preferably 160 ° C. to 270 ° C., and particularly preferably 180 ° C. to 260 ° C. When the mixing temperature is within the above preferred range, the fluidity does not decrease excessively, while the molecular weight of the mixture does not easily decrease.

The mixing time condition is preferably in the range of 0.1 to 30 minutes, more preferably in the range of 0.3 to 20 minutes, and particularly preferably in the range of 0.5 to 10 minutes. When the mixing time is within the above preferable range, the mixing of poly-L-lactic acid and poly-D-lactic acid becomes uniform, while thermal decomposition is hardly caused by mixing.

The pressure condition for mixing is not particularly limited, and may be any condition under an air atmosphere or an inert gas atmosphere such as nitrogen.

The mixing weight ratio of poly-L-lactic acid composed of L-lactic acid units and poly-D-lactic acid composed of D-lactic acid units is preferably from 80:20 to 20:80, and from 75:25 to The ratio is more preferably 25:75, further preferably 70:30 to 30:70, and particularly preferably 60:40 to 40:60. When the weight ratio of poly-L-lactic acid composed of L-lactic acid units is within the above preferred range, a polylactic acid stereocomplex is easily formed, and as a result, the resulting polylactic acid block copolymer has a sufficient melting point. growing.

In this mixing step, it is preferable to contain a catalyst in the mixture in order to promote transesterification of the L-lactic acid unit segment and the D-lactic acid unit segment efficiently. At this time, the catalyst may be a residual amount of the catalyst when producing poly-L-lactic acid and / or poly-D-lactic acid, or a catalyst may be further added in the mixing step.

The catalyst content is preferably 0.001 part by weight or more and 1 part by weight or less with respect to 100 parts by weight of the mixture of poly-L-lactic acid and poly-D-lactic acid. More preferred are parts by weight or less. When the catalyst amount is in the above preferred range, the frequency of transesterification of the mixture is sufficiently high, while the molecular weight of the finally obtained polylactic acid block copolymer tends to increase.

Next, by mixing the polyfunctional compound with poly-L-lactic acid and poly-D-lactic acid, the poly-L-lactic acid and poly-D-lactic acid are covalently bonded with the polyfunctional compound, and the polylactic acid block co-polymer is combined. A method for obtaining a polymer (Preparation Method 4) will be described. In polymerization of poly-L-lactic acid and poly-D-lactic acid used in this preparation method, any of the above-described ring-opening polymerization method and direct polymerization method can be used.

The weight-average molecular weight of poly-L-lactic acid and poly-D-lactic acid used to obtain a polylactic acid block copolymer by this method is such that the formation rate of stereocomplexes is high. It is preferable that the weight average molecular weight of any one of -D-lactic acid is 30,000 to 100,000 or less and the other weight average molecular weight is 10,000 to 30,000 or less. More preferably, one weight average molecular weight is 35,000 to 90,000 and the other weight average molecular weight is 10,000 to 25,000. Particularly preferably, one weight average molecular weight is 40,000 to 80,000, and the other weight average molecular weight is 10,000 to 20,000.

Further, the ratio of the weight average molecular weight of poly-L-lactic acid used in the above mixing to the weight average molecular weight of poly-D-lactic acid is 2 or more and less than 10 from the viewpoint of increasing the stereocomplex formation rate. Is preferred. More preferably, it is 3 or more and less than 10, and particularly preferably 4 or more and less than 10.

Examples of the polyfunctional compound used here include polyvalent carboxylic acid anhydrides, polyvalent carboxylic acid halides, polyvalent carboxylic acids, polyvalent isocyanates, polyvalent amines, polyhydric alcohols, and polyvalent epoxy compounds. Specifically, 1,2-cyclohexanedicarboxylic acid anhydride, succinic acid anhydride, phthalic acid anhydride, trimellitic acid anhydride, 1,8-naphthalenedicarboxylic acid anhydride, pyromellitic acid anhydride, etc. Polycarboxylic acid anhydrides, isophthalic acid chloride, terephthalic acid chloride, polyvalent carboxylic acid halides such as 2,6-naphthalenedicarboxylic acid chloride, succinic acid, adipic acid, sebacic acid, fumaric acid, terephthalic acid, isophthalic acid, 2 , 6-Polycarboxylic acids such as naphthalenedicarboxylic acid, hexamethylene diisocyanate, 4,4 ′ Polyvalent isocyanates such as diphenylmethane diisocyanate, toluene-2,4-diisocyanate, polyvalent amines such as ethylenediamine, hexanediamine, diethylenetriamine, ethylene glycol, propylene glycol, butanediol, hexanediol, glycerin, trimethylolpropane, pentaerythritol, etc. Polyhydric alcohol, terephthalic acid diglycidyl ester, naphthalene dicarboxylic acid diglycidyl ester, trimellitic acid triglycidyl ester, pyromellitic acid tetraglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, cyclohexane dimethanol diglycidyl ether , Glycerol triglycidyl ether, trimethylol B pan triglycidyl ether, polyvalent epoxy compounds such as pentaerythritol polyglycidyl ether and the like. Of these, polyvalent carboxylic acid anhydrides, polyvalent isocyanates, polyhydric alcohols and polyvalent epoxy compounds are preferred, and polyvalent carboxylic acid anhydrides, polyvalent isocyanates and polyvalent epoxy compounds are particularly preferred. Moreover, these can be used combining 1 type (s) or 2 or more types.

The mixing amount of the polyfunctional compound is preferably 0.01 parts by weight or more and 20 parts by weight or less, more preferably 0.1 parts by weight, with respect to 100 parts by weight of the total of poly-L-lactic acid and poly-D-lactic acid. More preferably, it is 10 parts by weight or less. When the addition amount of the polyfunctional compound is within the above preferable range, the effect of causing a covalent bond can be sufficiently exhibited.

Furthermore, when a polyfunctional compound is used, a reaction catalyst may be added in order to promote the reaction between poly-L-lactic acid and poly-D-lactic acid and the polyfunctional compound. Examples of the reaction catalyst include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, stearin. Sodium phosphate, potassium stearate, lithium stearate, sodium borohydride, lithium borohydride, sodium phenyl borohydride, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, Dilithium hydrogen phosphate, disodium salt of bisphenol A, dipotassium salt, dilithium salt, phenol sodium salt, potassium salt, lithium salt, cesium salt and other alkali metal compounds, calcium hydroxide, water Oxidation Alkaline earths such as lithium, magnesium hydroxide, strontium hydroxide, calcium bicarbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, magnesium stearate, strontium stearate Metal compounds, triethylamine, tributylamine, trihexylamine, triamylamine, triethanolamine, dimethylaminoethanol, triethylenediamine, dimethylphenylamine, dimethylbenzylamine, 2- (dimethylaminomethyl) phenol, dimethylaniline, pyridine, picoline , Tertiary amines such as 1,8-diazabicyclo (5,4,0) undecene-7, 2-methylimidazole, 2-ethyl Imidazole compounds such as ruimidazole, 2-isopropylimidazole, 2-ethyl-4-methylimidazole, 4-phenyl-2-methylimidazole, tetramethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium bromide, trimethylbenzylammonium chloride, triethyl Quaternary ammonium salts such as benzylammonium chloride, tripropylbenzylammonium chloride, N-methylpyridinium chloride, phosphine compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, tetramethylphosphonium bromide, tetrabutylphosphonium bromide, Tetraphenylphosphonium bromide, Eth Phosphonium salts such as rutriphenylphosphonium bromide, triphenylbenzylphosphonium bromide, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl Phosphate esters such as phosphate, octyl diphenyl phosphate, tri (p-hydroxy) phenyl phosphate, tri (p-methoxy) phenyl phosphate, oxalic acid, p-toluenesulfonic acid, dinonylnaphthalenedisulfonic acid, dodecylbenzenesulfonic acid, etc. Organic acids and Lewis acids such as boron trifluoride, aluminum tetrachloride, titanium tetrachloride, tin tetrachloride Etc. are exemplified, and these may be used in combination of one or two or more.

The amount of the catalyst added is preferably 0.001 part by weight or more and 1 part by weight or less with respect to 100 parts by weight of the total of poly-L-lactic acid and poly-D-lactic acid. When the catalyst amount is in the above preferred range, the reaction promoting effect is sufficient, while the molecular weight of the finally obtained polylactic acid block copolymer tends to increase.

The method for reacting poly-L-lactic acid or poly-D-lactic acid with a polyfunctional compound is not particularly limited. For example, of poly-L-lactic acid and poly-D-lactic acid, the one having the higher melting point. Examples of the method include melt kneading at a temperature higher than the melting end temperature of the components.

Examples of the method of melt-kneading at a temperature higher than the melting end temperature include a method of mixing poly-L-lactic acid and poly-D-lactic acid by a batch method or a continuous method. Examples include a single-screw extruder, a twin-screw extruder, a plastmill, a kneader, and a stirred tank reactor equipped with a decompression device. In terms of uniform and sufficient kneading, a single-screw extruder or a twin-screw extruder should be used. Is preferred.

Regarding the temperature condition for melting and kneading, it is preferable to carry out at a temperature higher than the melting end temperature of the component having a higher melting point among poly-L-lactic acid and poly-D-lactic acid. The range is preferably 140 ° C to 250 ° C, more preferably 160 ° C to 230 ° C, and particularly preferably 180 ° C to 210 ° C. When the mixing temperature is within the above preferred range, the fluidity does not decrease excessively, while the molecular weight of the mixture does not easily decrease.

The time condition for melt kneading is preferably in the range of 0.1 to 30 minutes, more preferably in the range of 0.3 to 20 minutes, and particularly preferably in the range of 0.5 to 10 minutes. When the mixing time is within the above preferable range, the mixing of poly-L-lactic acid and poly-D-lactic acid becomes uniform, while thermal decomposition is hardly caused by mixing.

The pressure condition for melt kneading is not particularly limited, and may be any condition under an air atmosphere or an inert gas atmosphere such as nitrogen.

The mixing weight ratio of poly-L-lactic acid composed of L-lactic acid units and poly-D-lactic acid composed of D-lactic acid units is preferably from 90:10 to 10:90, and from 80:20 to More preferably, it is 20:80. Particularly preferred is 75:25 to 60:40 or 40:60 to 25:75. When the weight ratio of poly-L-lactic acid composed of L-lactic acid units is within the above preferred range, a polylactic acid stereocomplex is easily formed, and as a result, the melting point of the polylactic acid block copolymer finally obtained is increased. Become big enough.

A polylactic acid block copolymer obtained by mixing a polyfunctional compound with poly-L-lactic acid and poly-D-lactic acid is a polyfunctional compound in which poly-L-lactic acid and poly-D-lactic acid are covalently bonded. Therefore, it is possible to carry out solid phase polymerization by the method described above after mixing.
<Polymer having a plurality of reactive groups in one molecule>
In the present invention, the polymer having a plurality of reactive groups per molecule is a polymer having a reactive group that undergoes an addition reaction with respect to the carboxyl group or hydroxyl group terminal of the polylactic acid resin composition. In the polylactic acid resin composition of the present invention, the viscosity of the polylactic acid resin composition is improved, and as a result, molding processability, mechanical properties, durability, and stability during heating are improved.

In the present invention, a polymer having a plurality of reactive groups per molecule may be included when preparing a polylactic acid block copolymer in addition to the above-mentioned polylactic acid resin composition. There is no particular limitation on the order of adding a polymer having a plurality of reactive groups per molecule in the process of producing a polylactic acid block copolymer. For example, when mixing poly-L-lactic acid and poly-D-lactic acid. It may be added, or may be added after mixing poly-L-lactic acid and poly-D-lactic acid. In addition, a polymer having a plurality of reactive groups per molecule may be included in advance with respect to poly-L-lactic acid or poly-D-lactic acid to be mixed. In the polylactic acid resin composition of the present invention, the content of the polymer having a plurality of reactive groups per molecule will be described later.

Here, as the type of polymer constituting a polymer having a plurality of reactive groups in one molecule, considering the moldability of a polylactic acid resin composition containing a polymer having a plurality of reactive groups in one molecule, The basic structure is a thermoplastic resin, and the weight average molecular weight (Mw) of the polymer is 1,000 to 15,000. By using a polymer having a weight average molecular weight within this range, the compatibility in the polylactic acid resin composition can be increased. Furthermore, if the weight average molecular weight (Mw) of the polymer is 2,000 to 10,000, the compatibility in the polylactic acid resin composition is higher, and the polylactic acid resin composition has molding processability, mechanical properties, Durability and stability during heating are improved. The weight average molecular weight (Mw) here is a weight average molecular weight in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent.

Specific examples of the reactive group that undergoes an addition reaction include a carbodiimide group, an epoxy group, an oxazoline group, an oxazine group, an aziridine group, and an isocyanate group. Among these, an epoxy group is preferable from the viewpoint of reactivity. The number of reactive groups contained in one molecule as a polymer having a plurality of reactive groups per molecule is preferably 2-30, more preferably 3-20, and even more preferably 4-10. .

In the present invention, when an acrylic resin reactive compound is used as a polymer having a plurality of reactive groups in one molecule, the acrylic resin reactive compound is a polymer of a mixture of an epoxy group-containing acrylic monomer and a styrene monomer, Or it is preferable that it is a polymer of 3 types of mixtures of an epoxy-group containing acrylic monomer, a styrene monomer, and another vinyl monomer. By including this acrylic resin-based reactive compound in the polylactic acid resin composition of the present invention, the viscosity of the polylactic acid resin composition is improved. As a result, molding processability, mechanical properties, durability, and stability during heating are stabilized. Will improve.

Here, specific examples of the epoxy group-containing acrylic monomer constituting the acrylic resin-based reactive compound include (meth) acrylic acid glycidyl, cyclohexene oxide structure (meth) acrylic acid ester, and (meth) acrylic acid glycidyl ether. Among these, glycidyl acrylate is preferably used in terms of radical polymerizability. These can be used alone or in combination of two or more.

Specific examples of the styrene monomer constituting the acrylic resin reactive compound include styrene, α-methyl styrene, vinyl toluene, p-methyl styrene, t-butyl styrene, o-chlorostyrene, vinyl pyridine and the like. Of these, one or more of styrene and α-methylstyrene are preferably used from the viewpoint of affinity with the polylactic acid block copolymer.

Specific examples of other vinyl monomers constituting the acrylic resin reactive compound include (meth) acrylic acid, (meth) methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) Butyl acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, lauryl (meth) acrylate, Stearyl (meth) acrylate, hydroxylethyl (meth) acrylate, hydroxypropyl (meth) acrylate, (meth) acrylate ester of polyethylene glycol or polypropylene glycol, trimethoxysilylpropyl (meth) acrylate, (meth) acrylonitrile , N, N-dia Examples include raw material monomers for forming acrylic vinyl units having amino groups such as kill (meth) acrylamide, α-hydroxymethyl acrylate ester, dimethylaminoethyl acrylate, and dimethylaminoethyl methacrylate. Acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, (meth) Preferred are 2-ethylhexyl acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and (meth) acrylonitrile. Further, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) ) Butyl acrylate, (meth) acrylic The acid 2-ethylhexyl, (meth) acrylonitrile is used. Also, (meth) acrylamide, (meth) acrylic dialkylamide, vinyl esters such as vinyl acetate, vinyl ethers, aromatic vinyl monomers such as (meth) allyl ethers, and α-olefin monomers such as ethylene and propylene It can be used. These can be used alone or in combination of two or more.

In the present invention, the acrylic resin-based reactive compound preferably contains 2 to 30 average epoxy groups per molecule, more preferably 3 to 20, and still more preferably 4 to 10. When the average number of epoxy groups is within this preferred range, the polylactic acid resin composition has an excellent thickening effect, and the moldability, mechanical properties, durability, and stability during heating are sufficiently improved, while excess epoxy is used. The group does not cause an excessive crosslinking reaction with the carboxyl group or hydroxyl group of the polylactic acid resin composition, and the moldability is not impaired.

In the present invention, the epoxy equivalent of the acrylic resin-based reactive compound containing an epoxy group is preferably 50 to 800 g / mol, more preferably 100 to 700 g / mol, and most preferably 150 from the viewpoint of reactivity and moldability. ~ 600 g / mol. Here, the epoxy equivalent and the carbodiimide equivalent represent the gram number of a polymer containing 1 equivalent of an epoxy group and the gram number of a polymer containing 1 equivalent of a carbodiimide group.

The weight average molecular weight (Mw) of the acrylic resin-based reactive compound containing an epoxy group is preferably 1,000 to 15,000, more preferably 2, from the viewpoint of reactivity and compatibility with the resin. 000 to 10,000. The weight average molecular weight (Mw) here is a weight average molecular weight in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography (GPC) using hexafluoroisopropanol as a solvent.

In the present invention, the acrylic resin-based reactive compound can be produced and used by a known technique, but a commercially available product can also be used. As a specific example of the commercially available product, Sumitomo Chemical Co., Ltd. "Bond First" (registered trademark) series, "Marproof" (registered trademark) series manufactured by NOF Corporation, "RESEDA" (registered trademark) series and "ARUFON" (registered trademark) series manufactured by Toagosei Co., Ltd. “JONCRYL” (registered trademark) series manufactured by BASF Japan Ltd. can be used preferably, but from the viewpoint of reactivity, “ARUFON” (registered trademark) series manufactured by Toagosei Co., Ltd. and BASF Japan Ltd. “ The JONCRYL "(registered trademark) series can be used more suitably.
<Polylactic acid resin composition>
The polylactic acid resin composition of the present invention comprises a polylactic acid block copolymer 100 comprising a poly-L-lactic acid segment containing L-lactic acid as a main component and a poly-D-lactic acid segment containing D-lactic acid as a main component. 0.05 to 2 parts by weight of a polymer having a plurality of reactive groups per molecule is contained with respect to parts by weight. The amount is preferably 0.1 to 1.5 parts by weight, more preferably 0.3 to 1.0 parts by weight. By containing a polymer having a plurality of reactive groups in one molecule in the polylactic acid resin within a preferable range, the viscosity of the polylactic acid resin composition is improved. As a result, molding processability, mechanical properties, durability, Stability during heating is improved. Moreover, gelation accompanying the increase in viscosity does not occur.

The polylactic acid resin composition obtained in the present invention preferably has a stereocomplex formation rate (Sc) in the range of 80 to 100% from the viewpoint of heat resistance. More preferably, it is in the range of 85 to 100%, and particularly preferably 90 to 100%. Here, the stereocomplex formation rate is the ratio of the stereocomplex crystals in all the crystals in the polylactic acid resin composition. Specifically, the crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal when the temperature is increased from 30 ° C. to 250 ° C. at a temperature rising rate of 20 ° C./min with a differential scanning calorimeter (DSC). It is possible to calculate by the following formula (8), where ΔH1 is the amount of heat based on and ΔHh is the amount of heat based on crystal melting of the stereocomplex crystal.

Sc = ΔHh / (ΔHl + ΔHh) × 100 (8)
In this invention, it is preferable that the temperature-falling crystallization temperature (Tc) is 130 degreeC or more at the point that a polylactic acid resin composition is excellent in a moldability and heat resistance. Here, the temperature drop crystallization temperature (Tc) of the compact is a constant temperature state at 250 ° C. for 3 minutes after being heated from 30 ° C. to 250 ° C. at a temperature rising rate of 20 ° C./min by a differential scanning calorimeter (DSC). Is a crystallization temperature derived from polylactic acid crystals measured when the temperature is lowered at a cooling rate of 20 ° C./min. The crystallization temperature (Tc) is not particularly limited, but is preferably 130 ° C. or higher, more preferably 132 ° C. or higher, and particularly preferably 135 ° C. or higher from the viewpoint of heat resistance and transparency.

Furthermore, in the polylactic acid resin composition of the present invention, the amount of crystallization when the polylactic acid resin composition is heated to 250 ° C. and kept constant for 3 minutes and then cooled at a cooling rate of 20 ° C./min in DSC measurement. Is 10 J / g or more. From the viewpoint of crystallization characteristics, molding cycle, and transparency of the molded body, it is preferably 10 J / g or more, more preferably 20 J / g or more, and particularly preferably 40 J / g or more.

Thus, even if the polylactic acid resin composition of the present invention contains a polymer having a plurality of reactive groups in one molecule, the temperature-falling crystallization temperature is 130 ° C. or higher, and the amount of crystallization during temperature-falling crystallization is 10 J / Since it is as high as g or more, it has not only excellent mechanical properties, durability and stability during heating, but also excellent heat resistance and crystallization characteristics.

The weight average molecular weight of the polylactic acid resin composition of the present invention is preferably 100,000 or more and less than 500,000 from the viewpoint of mechanical properties. More preferably, it is 120,000 or more and less than 450,000, and 130,000 or more and less than 400,000 is particularly preferable from the viewpoints of moldability, mechanical properties, and stability during heating.

Further, the dispersity of the polylactic acid resin composition is preferably in the range of 1.5 to 4.5 from the viewpoint of mechanical properties. The range of the degree of dispersion is more preferably from 1.8 to 3.7, and particularly preferably from 2.0 to 3.4 from the viewpoint of moldability and mechanical properties. The weight average molecular weight and dispersity are values in terms of standard polymethyl methacrylate as measured by gel permeation chromatography (GPC) using hexafluoroisopropanol or chloroform as a solvent.

In the polylactic acid resin composition of the present invention, in thermogravimetry (TGA), the heat loss when the polylactic acid resin composition is maintained at a constant temperature of 240 ° C. for 30 minutes under a nitrogen atmosphere may be 3% or less. preferable. More preferably, it is preferably 2% or less, particularly preferably less than 1%. A low heating loss is preferred because of excellent residence stability.

In the present invention, the ratio (MFR10 / MFR20) of the melt flow rate (MFR10) after 10 minutes to the melt flow rate (MFR20) after 20 minutes under the condition of 230 ° C. and 21.2N load of the polylactic acid resin composition is 0. A range of 5 or more and 2 or less is preferable in terms of moldability, mechanical properties, impact resistance, and stability during heating. More preferably, it is the range of 0.7 or more and 1.8 or less, More preferably, it is the range of 0.85 or more and 1.5 or less. The melt flow rate here is a value measured at 190 ° C. and 21.2 N load conditions according to JIS K 7210 using “Melt Indexer” manufactured by Toyo Seiki Seisakusho.

Regarding the method for producing the polylactic acid resin composition of the present invention, it is preferable to use any one of the following three methods (I) to (III) by using a heat-melt kneading apparatus such as an extruder or a kneader. Can be manufactured.

Examples of the method (I) for producing a polylactic acid resin composition include a method of melt-kneading a polylactic acid block copolymer and a polymer having a plurality of reactive groups in one molecule. As a method of melt kneading, either a batch method or a continuous method may be used. Examples of the kneading apparatus include a single screw extruder, a twin screw extruder, a plast mill, a kneader, and a stirred tank reactor equipped with a pressure reducing device. From the viewpoint of uniform and sufficient kneading, a single screw extruder and a twin screw extruder are used. It is preferable to use it.

As for the temperature condition for melt kneading, it is preferable to carry out at 180 ° C to 250 ° C. The range is more preferably 200 ° C. to 240 ° C., and further preferably 205 ° C. to 235 ° C. When the mixing temperature is within the above preferred range, the fluidity does not decrease excessively, while the molecular weight of the mixture does not easily decrease.

The time condition for melt kneading is preferably in the range of 0.1 to 30 minutes, more preferably in the range of 0.3 to 20 minutes, and particularly preferably in the range of 0.5 to 10 minutes. When the mixing time is within the above preferable range, the polylactic acid block copolymer and the polymer having a plurality of reactive groups per molecule are uniformly mixed, while thermal decomposition is hardly caused by mixing.

Next, as a production method (II) of the polylactic acid resin composition, poly-L-lactic acid and poly-D-lactic acid are mixed in advance, and then a polymer having a plurality of reactive groups per molecule is blended. And a method of subjecting the resulting mixture to solid phase polymerization at a temperature lower than the melting point of the mixture. The method of melt kneading in this method may be a mixing method applied in the above-described method for producing a polylactic acid resin composition, and the above-mentioned polylactic acid resin composition is also used for the kneading apparatus, temperature conditions, time conditions, and pressure conditions during mixing. This is the same as described in the manufacturing method.

Furthermore, as a method (III) for producing a polylactic acid resin composition, three types of poly-L-lactic acid, poly-D-lactic acid and a polymer having a plurality of reactive groups in one molecule are mixed together and then mixed. And a method of solid-phase polymerization at a temperature lower than the melting point. The method of melt kneading in this method may be a mixing method applied in the above-described method for producing a polylactic acid resin composition, and the above-mentioned polylactic acid resin composition is also used for the kneading apparatus, temperature conditions, time conditions, and pressure conditions during mixing. This is the same as described in the manufacturing method.

The polylactic acid resin composition of the present invention comprises a poly-L-lactic acid (segment consisting of L-lactic acid units) comprising L-lactic acid units of a polylactic acid resin finally obtained within a range not impairing the effects of the present invention, In order to enhance the alternation with poly-D-lactic acid composed of D-lactic acid units (segments composed of D-lactic acid units), a polyfunctional compound may be mixed.

The polyfunctional compound used here is not particularly limited, and polyvalent carboxylic acid anhydride, polyvalent carboxylic acid halide, polyvalent carboxylic acid, polyvalent isocyanate, polyvalent amine, polyhydric alcohol and Polyepoxy compounds and the like. Specifically, 1,2-cyclohexanedicarboxylic acid anhydride, succinic acid anhydride, phthalic acid anhydride, trimellitic acid anhydride, 1,8-naphthalenedicarboxylic acid anhydride, Polycarboxylic acid anhydrides such as pyromellitic acid anhydride, polycarboxylic acid halides such as isophthalic acid chloride, terephthalic acid chloride, 2,6-naphthalenedicarboxylic acid chloride, succinic acid, adipic acid, sebacic acid, fumaric acid , Terephthalic acid, isophthalic acid, polyvalent carboxylic acids such as 2,6-naphthalenedicarboxylic acid, hexamethyle Polyisocyanates such as diisocyanate, 4,4'-diphenylmethane diisocyanate, toluene-2,4-diisocyanate, polyvalent amines such as ethylenediamine, hexanediamine, diethylenetriamine, ethylene glycol, propylene glycol, butanediol, hexanediol, glycerin, tri Polyhydric alcohols such as methylolpropane and pentaerythritol, terephthalic acid diglycidyl ester, naphthalene dicarboxylic acid diglycidyl ester, trimellitic acid triglycidyl ester, pyromellitic acid tetraglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether , Cyclohexanedimethanol diglycidyl ether, glycerol triglyci Ether, trimethylolpropane triglycidyl ether, polyvalent epoxy compounds such as pentaerythritol polyglycidyl ether and the like. Of these, polyvalent carboxylic acid anhydrides, polyvalent isocyanates, polyhydric alcohols and polyvalent epoxy compounds are preferred, and polyvalent carboxylic acid anhydrides, polyvalent isocyanates and polyvalent epoxy compounds are particularly preferred. These may be used alone or in combination of two or more.

The mixing amount of the polyfunctional compound is preferably 0.01 parts by weight or more and 20 parts by weight or less, more preferably 0.1 parts by weight, with respect to 100 parts by weight of the total of poly-L-lactic acid and poly-D-lactic acid. More preferably, it is 10 parts by weight or less. The effect which uses a polyfunctional compound can be exhibited as the addition amount of a polyfunctional compound is the said preferable range.

Furthermore, when a polyfunctional compound is used, a reaction catalyst may be added in order to promote the reaction between poly-L-lactic acid and poly-D-lactic acid and the polyfunctional compound. Examples of the reaction catalyst include sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, stearin. Sodium phosphate, potassium stearate, lithium stearate, sodium borohydride, lithium borohydride, sodium phenyl borohydride, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, Dilithium hydrogen phosphate, disodium salt of bisphenol A, dipotassium salt, dilithium salt, phenol sodium salt, potassium salt, lithium salt, cesium salt and other alkali metal compounds, calcium hydroxide, water Oxidation Alkaline earths such as lithium, magnesium hydroxide, strontium hydroxide, calcium bicarbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, magnesium stearate, strontium stearate Metal compounds, triethylamine, tributylamine, trihexylamine, triamylamine, triethanolamine, dimethylaminoethanol, triethylenediamine, dimethylphenylamine, dimethylbenzylamine, 2- (dimethylaminomethyl) phenol, dimethylaniline, pyridine, picoline , Tertiary amines such as 1,8-diazabicyclo [5.4.0] -7-undecene, 2-methylimidazole, 2- Imidazole compounds such as til imidazole, 2-isopropyl imidazole, 2-ethyl-4-methylimidazole, 4-phenyl-2-methylimidazole, tetramethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium bromide, trimethylbenzylammonium chloride, triethyl Quaternary ammonium salts such as benzylammonium chloride, tripropylbenzylammonium chloride, N-methylpyridinium chloride, phosphine compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, tetramethylphosphonium bromide, tetrabutylphosphonium bromide, Tetraphenylphosphonium bromide, Phosphonium salts such as tritylphenylphosphonium bromide, triphenylbenzylphosphonium bromide, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl Phosphate esters such as diphenyl phosphate, octyl diphenyl phosphate, tri (p-hydroxy) phenyl phosphate, tri (p-methoxy) phenyl phosphate, oxalic acid, p-toluenesulfonic acid, dinonylnaphthalenedisulfonic acid, dodecylbenzenesulfonic acid, etc. Organic acids and Lewis such as boron trifluoride, aluminum tetrachloride, titanium tetrachloride, tin tetrachloride And the like, which can be used in combination of one or more kinds thereof.

The amount of the reaction catalyst added is preferably 0.001 part by weight or more and 0.5 part by weight or less with respect to 100 parts by weight of the total of poly-L-lactic acid and poly-D-lactic acid. When the catalyst amount is in the above preferred range, an effect of shortening the polymerization time can be obtained, while the molecular weight of the finally obtained polylactic acid resin can be increased.

In the polylactic acid resin composition of the present invention, conventional additives such as a catalyst deactivator (hindered phenol compound, thioether compound, vitamin compound, triazole compound) are used as long as the object of the present invention is not impaired. , Polyamine-based compounds, hydrazine derivative-based compounds, phosphorus-based compounds, etc., which may be used in combination, including at least one phosphorous-based compound, phosphate-based compound, phosphite-based More preferably, it is a compound or a metal phosphate inorganic compound.

Specific examples of the catalyst deactivator composed of a phosphorus compound include “ADEKA STAB” (registered trademark) AX-71 (dioftademil phosphate), PEP-8 (distearyl pentaerythritol diphosphite) manufactured by ADEKA, PEP -36 (cyclic neopentatetraylbis (2,6-t-butyl-4-methylphenyl) phosphite) or the like, or sodium dihydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid Lithium dihydrogen, calcium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, calcium hydrogen phosphate, sodium hydrogen phosphite, potassium phosphite, calcium hydrogen phosphite, sodium hypophosphite, At least one gold phosphate selected from potassium hypophosphite and calcium hypophosphite Salts inorganic compounds. Among these, sodium dihydrogen phosphate and potassium dihydrogen phosphate are more preferable.

When adding a plasticizer as a normal additive, for example, polyalkylene glycol plasticizer, polyester plasticizer, polycarboxylic acid ester plasticizer, glycerin plasticizer, phosphate ester plasticizer, epoxy Examples include plasticizers, fatty acid amides such as stearic acid amide and ethylenebisstearic acid amide, pentaerythritol, various sorbitols, polyacrylic acid esters, silicone oils and paraffins. From the viewpoint of bleed-out resistance, polyethylene glycol , Polypropylene glycol, poly (ethylene oxide / propylene oxide) block and / or random copolymer, polytetramethylene glycol, ethylene oxide addition polymer of bisphenols, propylene of bisphenols Polyalkylene glycols such as xoxide addition polymers, tetrahydrofuran addition polymers of bisphenols, or terminal end-capping compounds such as terminal epoxy-modified compounds, terminal ester-modified compounds, and terminal ether-modified compounds, polyalkylene glycol plasticizers, bis ( Butyl diglycol) adipate, methyl diglycol butyl diglycol adipate, benzyl methyl diglycol adipate, acetyl tributyl citrate, methoxycarbonylmethyl dibutyl citrate, ethoxycarbonylmethyl dibutyl citrate, etc. Monoacetomonolaurate, glycerol diacetomonolaurate, glycerol monoacetomonostearate, glycerol diacetomonooleate And glycerin plasticizers such as glycerin monoacetomonomontanate), impact modifiers (natural rubber, polyethylene such as low-density polyethylene and high-density polyethylene, polypropylene, impact-modified polystyrene, polybutadiene, styrene / butadiene) Polymer, ethylene / propylene copolymer, ethylene / methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / vinyl acetate copolymer, ethylene / glycidyl methacrylate copolymer, polyethylene terephthalate / poly (tetramethylene oxide) ) Glycol block copolymers, polyester elastomers such as polyethylene terephthalate / isophthalate / poly (tetramethylene oxide) glycol block copolymers, butadiene based copolymers such as MBS Examples thereof include an ash elastomer or an acrylic core-shell elastomer, and these may be used alone or in combination of two or more. Examples of butadiene-based or acrylic core-shell elastomers include “Metablene” (registered trademark) manufactured by Mitsubishi Rayon Co., Ltd., “Kaneace” (registered trademark) manufactured by Kaneka Co., Ltd., and “Paralloid” manufactured by Rohm & Haas Japan Co., Ltd. (Registered trademark, etc.), fillers (fibrous, plate-like, powdery, granular, etc.), specifically, glass fiber, PAN-based or pitch-based carbon fiber, Stainless steel fiber, metal fiber such as aluminum fiber and brass fiber, organic fiber such as aromatic polyamide fiber, gypsum fiber, ceramic fiber, asbestos fiber, zirconia fiber, alumina fiber, silica fiber, titanium oxide fiber, silicon carbide fiber, rock wool , Potassium titanate whisker, barium titanate whisker, aluminum borate whisker, nitride nitride Fibrous, whisker-like filler, kaolin, silica, calcium carbonate, glass beads, glass flake, glass microballoon, molybdenum disulfide, wollastonite, montmorillonite, titanium oxide, zinc oxide, calcium polyphosphate, graphite, sulfuric acid Flame retardants (red phosphorus, brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, magnesium hydroxide, melamine and cyanuric acid or salts thereof, silicon compounds, etc.), UV absorbers (resorcinol, salicylate, benzotriazole) , Benzophenone, etc.), heat stabilizers (such as hindered phenols, hydroquinones, phosphites and their substitutes), lubricants, mold release agents (montanic acid and its salts, esters thereof, Half-esters, stearyl alcohol, stearamide and polyethylene waxes), colorants including dyes (eg nigrosine) and pigments (eg cadmium sulfide, phthalocyanine), anti-coloring agents (eg phosphites, hypophosphites), Examples thereof include a conductive agent or a colorant (carbon black, etc.), a slidability improver (graphite, a fluororesin, etc.), an antistatic agent, and the like, and one kind or two or more kinds can be added.

The polylactic acid resin composition used in the present invention may further contain poly-L-lactic acid and / or poly-D-lactic acid in addition to the above-mentioned polylactic acid block copolymer, as long as the object of the present invention is not impaired. it can.

Here, poly-L-lactic acid is a polymer containing L-lactic acid as a main component, preferably containing 70 mol% or more of L-lactic acid units, and containing 90 mol% or more. Is more preferably 95 mol% or more, and particularly preferably 98 mol% or more.

Poly-D-lactic acid is a polymer containing D-lactic acid as a main component, and preferably contains 70 mol% or more of D-lactic acid units, more preferably 90 mol% or more. More preferably, it is more preferably 95 mol% or more, and particularly preferably 98 mol% or more.

In the present invention, poly-L-lactic acid and poly-D-lactic acid may contain other component units as long as the performance of the resulting polylactic acid resin composition is not impaired. Component units other than the L-lactic acid or D-lactic acid unit are included for the segment containing L-lactic acid as the main component or the segment containing D-lactic acid as the main component that constitutes the polylactic acid block copolymer. Examples of other component units that may be used include polycarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, and lactones.

The weight average molecular weight of poly-L-lactic acid or poly-D-lactic acid used in the present invention is not particularly limited, but is preferably 100,000 or more from the viewpoint of mechanical properties. 120,000 or more is more preferable, and 140,000 or more is particularly preferable in terms of moldability and mechanical properties. Further, the dispersity of poly-L-lactic acid or poly-D-lactic acid is preferably in the range of 1.5 to 3.0 from the viewpoint of mechanical properties. The range of the degree of dispersion is more preferably 1.8 to 2.7, and 2.0 to 2.4 is particularly preferable in terms of moldability and mechanical properties. The weight average molecular weight and dispersity are values in terms of standard polymethyl methacrylate as measured by gel permeation chromatography (GPC) using hexafluoroisopropanol or chloroform as a solvent.

The order of mixing poly-L-lactic acid and / or poly-D-lactic acid with respect to the polylactic acid resin composition is not particularly limited, and poly-L-lactic acid and / or poly with respect to the polylactic acid resin composition is not limited. -D-lactic acid may be mixed, or poly-L-lactic acid and / or poly-D-lactic acid is mixed in advance to form a polylactic acid block copolymer and a polymer having a plurality of reactive groups in one molecule. You may mix.

The amount of poly-L-lactic acid and / or poly-D-lactic acid contained in the polylactic acid resin composition is preferably 10 parts by weight or more and 900 parts by weight or less with respect to 100 parts by weight of the polylactic acid resin composition. 30 to 400 parts by weight is preferable. When the poly-L-lactic acid and / or poly-D-lactic acid in the polylactic acid resin composition is in the above preferred range, the stereocomplex forming property can be improved, which is preferable.

Further, the polylactic acid resin composition of the present invention includes other thermoplastic resins (for example, polyethylene, polypropylene, polystyrene, acrylic resin, acrylonitrile / butadiene / styrene copolymer, polyamide, and the like within a range not to impair the purpose of the present invention). , Polycarbonate, polyphenylene sulfide resin, polyether ether ketone resin, polyester, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyetherimide, cellulose ester, etc.) or thermosetting resin (eg, phenol resin, melamine resin, polyester resin, silicone) Resin, epoxy resin, etc.) or soft thermoplastic resin (for example, ethylene / glycidyl methacrylate copolymer, polyester elastomer, polyamide elastomer, ethylene / B pyrene terpolymer, and ethylene / butene-1 copolymer) can further contain at least one or more such.

In the case of using an acrylic resin in the present invention, an acrylic resin having an alkyl (meth) acrylate unit having an alkyl group having 1 to 4 carbon atoms as a main component is preferably mentioned. In addition, an alkyl (meth) acrylate having an alkyl group having 1 to 4 carbon atoms may be copolymerized with another alkyl acrylate having an alkyl group having 1 to 4 carbon atoms or an aromatic vinyl compound such as styrene. Good.

Examples of the alkyl (meth) acrylate having the above alkyl group include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate. Can be mentioned. When an acrylic resin is used in the present invention, polymethyl methacrylate composed of methyl methacrylate is particularly preferable.

The polylactic acid resin composition of the present invention has a characteristic that, when it is processed into a molded product as a molded body, it is easy to form a high melting point polylactic acid stereocomplex even after it is once melted by heat and solidified.

The molded product of the present invention preferably has a relative crystallinity of 90% or more and a molded product having a thickness of 1 mm has a haze value of 10% or less.

Here, the relative crystallinity can be calculated by the following formula (9), where ΔHm is the crystal melting enthalpy of the molded body and ΔHc is the crystallization enthalpy at the time of temperature rising of the molded body.

Relative crystallinity = [(ΔHm−ΔHc) / ΔHm] × 100 (9)
The relative crystallinity is preferably 90% or more, more preferably 92% or more, and particularly preferably 94% or more. Here, ΔHc is the crystallization enthalpy of the molded body measured by a differential scanning calorimeter (DSC) at a heating rate of 20 ° C./min, and ΔHm is measured by DSC at a heating rate of 20 ° C./min. This is the crystal melting enthalpy of the molded body. After the temperature was increased from 30 ° C. to 250 ° C. at a temperature increase rate of 20 ° C./min in the first measurement (1st RUN), the temperature was cooled to 30 ° C. at a temperature decrease rate of 20 ° C./min. Furthermore, when the temperature is increased from 30 ° C. to 250 ° C. at a rate of temperature increase of 20 ° C./min in the second measurement (2nd RUN), it is preferably the crystal melting enthalpy measured at 2 nd RUN.

Further, the haze value is a value obtained by measuring a 1 mm-thick molded body in accordance with JIS K 7105. In terms of transparency, the haze value is preferably 10% or less, and more preferably 7% or less. preferable. Although a minimum is not specifically limited, If it is 0.1% or more, it can be used practically without a problem. Moreover, even if the molded object of this invention does not contain the crystal nucleating agent used in order to improve transparency, it can make haze value 10% or less by thickness 1mm or more.

Examples of the method for producing the molded product of the present invention include known molding methods such as injection molding, extrusion molding, blow molding, vacuum molding, and press molding. In terms of transparency and heat resistance, injection molding and blow molding are possible. Vacuum molding and press molding are preferred.

When injection molding is performed as the method for producing a molded article of the present invention, the mold temperature is a temperature range from the glass transition temperature of the polylactic acid resin composition to the melting point and below the melting point, preferably 60 in terms of transparency and heat resistance. Set to a temperature range of from 70 ° C. to 240 ° C., more preferably from 70 ° C. to 220 ° C., more preferably from 80 ° C. to 200 ° C., and a molding cycle of 150 seconds or less, preferably Is preferably 90 seconds or less, more preferably 60 seconds or less, and even more preferably 50 seconds or less.

When blow molding is performed as a method for producing a molded article of the present invention, for example, a polylactic acid resin composition is molded into a bottomed tubular product (parison) by injection molding using the above method, and then a polylactic acid resin is formed. For blow molding set to a temperature range of not less than the glass transition point of the composition and a glass transition point of + 80 ° C. or less, preferably 60 ° C. or more and 140 ° C. or less, more preferably 70 ° C. or more and 130 ° C. or less. There is a method of obtaining a molded body by moving to the mold and supplying compressed air from an air nozzle while stretching with a stretching rod.

When vacuum forming is performed as a method for producing the molded article of the present invention, the polylactic acid resin composition is heated at 60 to 150 ° C., preferably 65 to 120 ° C. with a heater such as a hot plate or hot air, in terms of transparency and heat resistance. At the same time, the sheet is heated at 70 ° C., more preferably 70 to 90 ° C., and the sheet is brought into close contact with the mold set at a mold temperature of 30 to 150 ° C., preferably 40 to 100 ° C., more preferably 50 to 90 ° C. There is a method of molding by depressurizing the inside of the mold.

When press molding is performed as a method for producing a molded article of the present invention, the polylactic acid resin composition is heated at 60 to 150 ° C., preferably 65 to 120 ° C. with a heater such as a hot plate or hot air, in terms of transparency and heat resistance. A mold comprising a male mold and a female mold, which is heated at 70 ° C., more preferably 70-90 ° C., and the sheet is set at a mold temperature of 30-150 ° C., preferably 40-100 ° C., more preferably 50-90 ° C. There is a method in which pressure is applied in close contact with the mold and the mold is clamped.

Since the molded product made of the polylactic acid resin composition of the present invention is characterized by having transparency without being subjected to stretching treatment, it is not necessary to perform stretching treatment in order to impart transparency, but other necessity It is possible to perform a stretching process according to the above. The shape of the formed body to be stretched is preferably a film or sheet shape. Further, when performing the stretching treatment, the temperature range of the polylactic acid stereocomplex above the glass transition point and below the melting point, preferably 60 ° C. or higher and 170 ° C. or lower, more preferably 70 ° C. or higher and 150 ° C. or lower. It is preferable to stretch in the temperature range.

The polylactic acid resin composition and the molded product containing the polylactic acid resin composition of the present invention include, for example, a film, a sheet, a fiber / cloth, a nonwoven fabric, an injection molded product, an extrusion molded product, a vacuum / pressure molded product, a blow molded product, and Can be used as a composite with other materials, such as agricultural materials, horticultural materials, fishery materials, civil engineering / building materials, stationery, medical supplies, automotive parts, electrical / electronic parts, optical films or other It is useful as an application.

Specifically, mobile terminals such as relay cases, coil bobbins, optical pickup chassis, motor cases, notebook computer housings or internal parts, CRT display housings or internal parts, printer housings or internal parts, mobile phones, mobile PCs, handheld mobiles, etc. Housing / internal parts, recording medium (CD, DVD, PD, FDD, etc.) drive housing or internal parts, copier housing or internal parts, facsimile housing or internal parts, parabolic antenna Can be mentioned. In addition, VTR parts, TV parts, irons, hair dryers, rice cooker parts, microwave oven parts, acoustic parts, video cameras, video equipment parts such as projectors, "Laser Disk (registered trademark)", Compact Disc (CD), CD -ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD-RW, DVD-RAM, Blu-ray disc and other optical recording media substrates, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, Home and office electrical product parts represented by word processor parts can be listed. Also, housings and internal parts of electronic musical instruments, home game machines, portable game machines, various gears, various cases, sensors, LEP lamps, connectors, sockets, resistors, relay cases, switches, coil bobbins, capacitors, variable capacitor cases, Optical pickups, oscillators, various terminal boards, transformers, plugs, printed wiring boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, semiconductors, liquid crystals, FDD carriages, FDD chassis, motor brush holders , Electrical and electronic parts such as transformer members, coil bobbins, sash doors, blind curtain parts, piping joints, curtain liners, blind parts, gas meter parts, water meter parts, water heater parts, roof panels, Hot walls, adjusters, plastic bundles, ceiling fishing gear, stairs, doors, floors and other building materials, fishing bait bags and other marine products, vegetation nets, vegetation mats, grass bags, grass nets, curing sheets, slopes Protection sheet, fly ash presser sheet, drain sheet, water retention sheet, sludge / sludge dewatering bag, civil engineering parts such as concrete formwork, air flow meter, air pump, thermostat housing, engine mount, ignition hobbin, ignition case, clutch bobbin, sensor Housing, idle speed control valve, vacuum switching valve, ECU (Electric Control Unit) housing, vacuum pump case, inhibitor switch, rotation sensor, acceleration sensor, distributor cap Coil base, ABS actuator case, radiator tank top and bottom, cooling fan, fan shroud, engine cover, cylinder head cover, oil cap, oil pan, oil filter, fuel cap, fuel strainer, distributor cap, vapor canister housing, Air cleaner housing, timing belt cover, brake booster parts, various cases, various tubes, various tanks, various hoses, various clips, various valves, various pipes, automotive underhood parts, torque control levers, safety belt parts, register blades , Washer lever, window regulator handle, window regulator handle knob, passing Automotive interior parts such as light levers, sun visor brackets, various motor housings, roof rails, fenders, garnishes, bumpers, door mirror stays, spoilers, hood louvers, wheel covers, wheel caps, grill apron cover frames, lamp reflectors, lamp bezels, Automotive exterior parts such as door handles, wire harness connectors, SMJ connectors (connectors for relay connection), PCB connectors (board connectors), door grommet connectors, various automotive connectors, gears, screws, springs, bearings, levers, key stems, Cams, ratchets, rollers, water supply parts, toy parts, fans, guts, pipes, cleaning jigs, motor parts, microscopes, binoculars, cameras, clocks and other mechanical parts, multi Film, tunnel film, bird-proof sheet, seedling pot, vegetation pile, seed string tape, germination sheet, house lining sheet, farm-bi fastener, slow-release fertilizer, root-proof sheet, garden net, insect net, Infant tree nets, printed laminates, fertilizer bags, sample bags, sandbags, animal damage prevention nets, incentive strings, windbreak nets and other agricultural materials, anti-mud materials (fibers) and molding materials used when mining shale gas and oil, Hygiene products, medical products such as medical films, packaging films for calendars, stationery, clothing, food, trays, blisters, knives, forks, spoons, tubes, plastic cans, pouches, containers, tanks, containers, etc. Tableware, hot fill containers, microwave cooking containers, transparent heat-resistant containers for foods, cosmetic containers, wraps, foam buffer, paper lami, shampoo Bottles, beverage bottles, cups, candy packaging, shrink labels, lid materials, envelopes with windows, fruit baskets, hand cut tape, easy peel packaging, egg packs, HDD packaging, compost bags, recording media packaging, shopping bags, electricity -Containers and packaging for wrapping films such as electronic parts, various apparel, interior goods, carrier tapes, print laminates, thermal stencil printing films, release films, porous films, container bags, credit cards, cash cards, ID cards , IC card, optical element, conductive embossed tape, IC tray, golf tee, garbage bag, plastic bag, various nets, toothbrush, stationery, clear file, bag, chair, table, cooler box, kumade, hose reel, planter, Hose nozzle, table, desk surface Useful as furniture panels, kitchen cabinets, pen caps, gas lighters, etc.

Hereinafter, the present invention will be described with reference to examples and the like, but the present invention is not limited to these examples. Here, the number of parts in the examples indicates parts by weight. Measuring methods for physical properties and the like are as follows. In addition, the measurement site | part of a molded object has selected and measured the same part.
(1) Molecular weight The weight average molecular weight and dispersity of a polylactic acid resin composition are the values of standard polymethylmethacrylate conversion measured by gel permeation chromatography (GPC). For GPC measurement, a differential refractometer WATERS410 manufactured by Nippon Waters Co., Ltd. is used as a detector, a MODEL510 manufactured by Nippon Waters Co., Ltd. is used as a pump, and “Shodex” (registered trademark) manufactured by Showa Denko Co., Ltd. is used as a column. GPC HFIP-806M and “Shodex” (registered trademark) GPC HFIP-LG were used in series. The measurement conditions were a flow rate of 0.5 mL / min, and in the measurement, hexafluoroisopropanol was used as a solvent, and 0.1 mL of a solution having a sample concentration of 1 mg / mL was injected.
(2) Thermal characteristics The melting point and heat of fusion of the polylactic acid resin composition were measured with a differential scanning calorimeter (DSC) manufactured by PerkinElmer Japan. Measurement conditions are a sample of 5 mg, a nitrogen atmosphere, and a heating rate of 20 ° C./min.

Here, the melting point refers to the peak top temperature in the crystal melting peak, and the melting end temperature refers to the peak end temperature in the crystal melting peak. In the obtained results, those in which the melting point was confirmed to be 190 ° C. or higher and lower than 250 ° C. were judged as polylactic acid stereocomplexes formed, and those in which the melting point was confirmed to be 150 ° C. or higher and lower than 190 ° C. It was judged that a lactic acid stereocomplex was not formed. The melting point of the polylactic acid resin composition shown here indicates the melting point measured when the temperature is raised from 30 ° C. to 250 ° C. at a rate of temperature rise of 20 ° C./min during the second temperature rise.

Also, the parameter value represented by the following formula (10) was calculated as the thermal characteristics.

(Tm-Tms) / (Tme-Tm) (10)
In the parameters of the formula (10), Tm: melting point derived from the stereocomplex crystal of the polylactic acid resin composition (peak top temperature at the crystal melting peak), Tms: stereocomplex crystal melting start temperature of the polylactic acid resin composition, Tme: poly The melting point end temperature derived from the stereocomplex crystal of the lactic acid resin composition is shown, and each value is measured using a differential scanning calorimeter (DSC) manufactured by PerkinElmer Japan Co., Ltd., in a 5 mg sample under a nitrogen atmosphere. Value. The measured value was raised from 30 ° C. to 250 ° C. at a rate of temperature rise of 40 ° C./min at the first temperature rise, then cooled to 30 ° C. at a temperature drop rate of 40 ° C./min, and further raised at the second temperature rise. The value when the temperature is raised from 30 ° C. to 250 ° C. at a temperature rate of 40 ° C./min is used.
(3) Stereo complex formation rate (Sc)
The stereocomplex formation rate (Sc) of the polylactic acid resin composition was calculated from the following formula (4).

Sc = ΔHh / (ΔHl + ΔHh) × 100 (4)
Here, ΔHl indicates the amount of heat based on crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal appearing at 150 ° C. or more and less than 190 ° C., and ΔHh is a stereocomplex crystal appearing at 190 ° C. or more and less than 250 ° C. The amount of heat based on the crystal melting of is shown.

Further, the stereocomplex formation rate (Sc) of the polylactic acid resin composition in this example is calculated from the crystal melting peak measured at the second temperature rise of the differential scanning calorimeter (DSC).
(4) Temperature-falling crystallization temperature The temperature-falling crystallization temperature of the polylactic acid resin composition was measured with a differential scanning calorimeter (DSC) manufactured by PerkinElmer Japan. Specifically, 5 mg of a sample was heated from 30 ° C. to 250 ° C. at a temperature rising rate of 20 ° C./min in a nitrogen atmosphere with a differential scanning calorimeter (DSC), and then kept at a constant temperature at 250 ° C. for 3 minutes. The temperature at the top of the crystallization peak measured when the temperature was lowered at a cooling rate of 20 ° C./min was taken as the lowered crystallization temperature.
(5) Crystallization enthalpy (ΔHc)
The peak area of the crystallization peak of the polylactic acid resin composition measured by a differential scanning calorimeter (DSC) is calculated.
(6) Loss on heating The loss on heating of the polylactic acid resin composition was measured with a thermogravimetric measuring device (TGA) manufactured by PerkinElmer Japan. Specifically, 3 mg of the sample was maintained in a constant temperature state at 240 ° C. for 30 minutes in a nitrogen atmosphere by a thermogravimetric apparatus (TGA), and the heating loss was calculated from the weight before and after the heating of the polylactic acid resin composition.
(7) Melt viscosity ratio (MFR10 / MFR20)
The melt viscosity ratio (MFR10 / MFR20) of the polylactic acid resin composition is in accordance with JIS K 7210, the melt flow rate after 10 minutes (MFR10) and the melt flow rate after 20 minutes (MFR20) at 230 ° C. and 21.2 N load conditions. ) Was measured with a melt indexer manufactured by Toyo Seiki Seisakusho, and the ratio (MFR10 / MFR20) was calculated from each value.
(8) Haze value The haze value was measured as an index of the transparency of the molded body made of the polylactic acid resin composition. Using a Nippon Denshoku Industries Co., Ltd. haze meter NDH-300A, a haze value was measured according to JIS K 7105 for a sheet-like molded body having a thickness of 0.1 mm.
(9) Storage elastic modulus at 130 ° C. The storage elastic modulus was measured as an index of the heat resistance of the molded body made of the polylactic acid resin composition. A center part of a sheet-like molded body having a thickness of 1 mm is cut into 40 mm × 2 mm to form a strip-like sample, and a temperature rise rate in a nitrogen atmosphere using a dynamic viscoelasticity measuring apparatus (DMS6100 manufactured by Seiko Instruments Inc.). Dynamic viscoelasticity measurement was performed at 2 ° C / min and a frequency of 3.5 Hz, and the storage elastic modulus at 130 ° C was measured. It can be said that the higher the elastic modulus, the higher the heat resistance.
(10) Tensile strength A 1 mm thick sheet-like molded body made of a polylactic acid resin composition was cut into a 40 mm × 2 mm strip to obtain a strip-like sample, and the tensile strength was measured according to ASTM D882.

The poly-L-lactic acid and poly-D-lactic acid used in the present examples (Examples 1 to 15 and Comparative Examples 1 to 17) are as follows.

PLA1: Poly-L-lactic acid obtained in Reference Example 1 (Mw = 50,000, dispersity 1.5)
PLA2: Poly-L-lactic acid obtained in Reference Example 2 (Mw = 140,000, dispersity 1.6)
PLA3: Poly-L-lactic acid obtained in Reference Example 3 (Mw = 200,000, dispersity 1.7)
PDA1: Poly-D-lactic acid obtained in Reference Example 4 (Mw = 40,000, dispersity 1.5)
PDA2: Poly-D-lactic acid obtained in Reference Example 5 (Mw = 70,000, dispersity 1.5)
PDA3: poly-D-lactic acid obtained in Reference Example 6 (Mw = 130,000, dispersity 1.6)
PDA4: Poly-D-lactic acid obtained in Reference Example 7 (Mw = 180,000, dispersity 1.6)
[Reference Example 1]
In a reaction vessel equipped with a stirrer and a reflux device, 50 parts of a 90% L-lactic acid aqueous solution was placed, the temperature was raised to 150 ° C., and the mixture was reacted for 3.5 hours while gradually reducing the pressure to distill off water. Thereafter, the pressure was increased to normal pressure in a nitrogen atmosphere, 0.02 part of tin (II) acetate was added, and then the polymerization reaction was performed for 7 hours while gradually reducing the pressure to 170 Pa at 170 ° C. Subsequently, the obtained poly-L-lactic acid was crystallized under a nitrogen atmosphere at 110 ° C. for 1 hour, and then at a pressure of 60 Pa at 140 ° C. for 3 hours, 150 ° C. for 3 hours, and 160 ° C. for 5 hours. Solid phase polymerization was carried out to obtain poly-L-lactic acid (PLA1). PLA1 had a weight average molecular weight of 50,000, a dispersity of 1.5, and a melting point of 157 ° C.
[Reference Example 2]
In a reaction vessel equipped with a stirrer and a reflux device, 50 parts of a 90% L-lactic acid aqueous solution was placed, the temperature was raised to 150 ° C., and the mixture was reacted for 3.5 hours while gradually reducing the pressure to distill off water. Thereafter, the pressure was increased to normal pressure in a nitrogen atmosphere, 0.02 part of tin (II) acetate was added, and then the polymerization reaction was performed for 7 hours while gradually reducing the pressure to 170 Pa at 170 ° C. Subsequently, the obtained poly-L-lactic acid was crystallized at 110 ° C. for 1 hour in a nitrogen atmosphere, and then at a pressure of 60 Pa for 3 hours at 140 ° C., 3 hours at 150 ° C., and 12 hours at 160 ° C. Solid-phase polymerization was performed for time to obtain poly-L-lactic acid (PLA2). PLA2 had a weight average molecular weight of 140,000, a dispersity of 1.6, and a melting point of 165 ° C.
[Reference Example 3]
In a reaction vessel equipped with a stirrer and a reflux device, 50 parts of a 90% L-lactic acid aqueous solution was placed, the temperature was raised to 150 ° C., and the mixture was reacted for 3.5 hours while gradually reducing the pressure to distill off water. Thereafter, the pressure was increased to normal pressure in a nitrogen atmosphere, 0.02 part of tin (II) acetate was added, and then the polymerization reaction was performed for 7 hours while gradually reducing the pressure to 170 Pa at 170 ° C. Subsequently, the obtained poly-L-lactic acid was crystallized at 110 ° C. for 1 hour in a nitrogen atmosphere, and then at a pressure of 60 Pa for 3 hours at 140 ° C., 3 hours at 150 ° C., and 18 hours at 160 ° C. Solid-phase polymerization was performed for time to obtain poly-L-lactic acid (PLA3). PLA3 had a weight average molecular weight of 200,000, a dispersity of 1.7, and a melting point of 170 ° C.
[Reference Example 4]
In a reaction vessel equipped with a stirrer and a reflux apparatus, 50 parts of a 90% D-lactic acid aqueous solution was placed, the temperature was raised to 150 ° C., and the mixture was reacted for 3.5 hours while gradually reducing the pressure to distill off water. Thereafter, the pressure was increased to normal pressure in a nitrogen atmosphere, 0.02 part of tin (II) acetate was added, and then the polymerization reaction was performed for 7 hours while gradually reducing the pressure to 170 Pa at 170 ° C. Subsequently, the obtained poly-D-lactic acid was crystallized under a nitrogen atmosphere at 110 ° C. for 1 hour, and then at a pressure of 60 Pa at 140 ° C. for 3 hours, 150 ° C. for 3 hours, and 160 ° C. for 5 hours. Solid-phase polymerization was performed for time to obtain poly-D-lactic acid (PDA1). PDA1 had a weight average molecular weight of 40,000, a dispersity of 1.5, and a melting point of 156 ° C.
[Reference Example 5]
In a reaction vessel equipped with a stirrer and a reflux apparatus, 50 parts of a 90% D-lactic acid aqueous solution was placed, the temperature was raised to 150 ° C., and the mixture was reacted for 3.5 hours while gradually reducing the pressure to distill off water. Thereafter, the pressure was increased to normal pressure in a nitrogen atmosphere, 0.02 part of tin (II) acetate was added, and then the polymerization reaction was performed for 7 hours while gradually reducing the pressure to 170 Pa at 170 ° C. Subsequently, the obtained poly-D-lactic acid was crystallized at 110 ° C. for 1 hour in a nitrogen atmosphere, and then at a pressure of 60 Pa, 140 ° C. for 3 hours, 150 ° C. for 3 hours, and 160 ° C. for 9 hours. Solid phase polymerization was carried out to obtain poly-D-lactic acid (PDA2). PDA2 had a weight average molecular weight of 7 million, a dispersity of 1.5, and a melting point of 161 ° C.
[Reference Example 6]
In a reaction vessel equipped with a stirrer and a reflux apparatus, 50 parts of a 90% D-lactic acid aqueous solution was placed, the temperature was raised to 150 ° C., and the mixture was reacted for 3.5 hours while gradually reducing the pressure to distill off water. Thereafter, the pressure was increased to normal pressure in a nitrogen atmosphere, 0.02 part of tin (II) acetate was added, and then the polymerization reaction was performed for 7 hours while gradually reducing the pressure to 170 Pa at 170 ° C. Subsequently, the obtained poly-D-lactic acid was crystallized at 110 ° C. for 1 hour in a nitrogen atmosphere, and then at a pressure of 60 Pa for 3 hours at 140 ° C., 3 hours at 150 ° C., and 12 hours at 160 ° C. Solid phase polymerization was carried out to obtain poly-D-lactic acid (PDA3). PDA3 had a weight average molecular weight of 130,000, a dispersity of 1.6, and a melting point of 164 ° C.
[Reference Example 7]
In a reaction vessel equipped with a stirrer and a reflux device, 50 parts of a 90% D-lactic acid aqueous solution was placed, the temperature was adjusted to 150 ° C., and the mixture was reacted for 3.5 hours while gradually reducing the pressure to distill off water. Thereafter, the pressure was increased to normal pressure in a nitrogen atmosphere, 0.02 part of tin (II) acetate was added, and then the polymerization reaction was performed for 7 hours while gradually reducing the pressure to 170 Pa at 170 ° C. Subsequently, the obtained poly-D-lactic acid was subjected to crystallization treatment at 110 ° C. for 1 hour in a nitrogen atmosphere, and then at a pressure of 60 Pa for 3 hours at 140 ° C., 3 hours at 150 ° C., and 18 hours at 160 ° C. Solid phase polymerization was carried out to obtain poly-D-lactic acid (PDA4). PDA4 had a weight average molecular weight of 180,000, a dispersity of 1.6, and a melting point of 168 ° C.
(A) Polylactic acid resin A-1: Polylactic acid stereocomplex obtained in Reference Example 8 (mixture of poly-L-lactic acid and poly-D-lactic acid) (Mw = 110,000, dispersity 2.7)
A-2: Polylactic acid block copolymer obtained in Reference Example 9 (Mw = 130,000, dispersity 2.4)
A-3: Polylactic acid stereocomplex obtained in Reference Example 10 (mixture of poly-L-lactic acid and poly-D-lactic acid) (Mw = 130,000, dispersity 2.6)
A-4: Polylactic acid block copolymer obtained in Reference Example 11 (Mw = 160,000, dispersity 2.3)
A-5: Polylactic acid stereocomplex obtained in Reference Example 12 (mixture of poly-L-lactic acid and poly-D-lactic acid) (Mw = 40,000, dispersity 1.8)
A-6: Polylactic acid block copolymer obtained in Reference Example 13 (Mw = 60,000, dispersity 1.6)
A-7: Polylactic acid stereocomplex (mixture of poly-L-lactic acid and poly-D-lactic acid) obtained in Reference Example 14 (Mw = 100,000, dispersity 2.2)
A-8: Polylactic acid block copolymer obtained in Reference Example 15 (Mw = 130,000, dispersity 2.0)
A-9: Polylactic acid stereocomplex obtained in Reference Example 16 (mixture of poly-L-lactic acid and poly-D-lactic acid) (Mw = 120,000, dispersity 2.4)
A-10: Polylactic acid block copolymer obtained in Reference Example 17 (Mw = 140,000, degree of dispersion 2.2)
A-11: Polylactic acid stereocomplex obtained in Reference Example 18 (mixture of poly-L-lactic acid and poly-D-lactic acid) (Mw = 130,000, dispersity 2.5)
A-12: Polylactic acid block copolymer obtained in Reference Example 19 (Mw = 150,000, dispersity 2.3)
A-13: Polylactic acid stereocomplex obtained in Reference Example 20 (mixture of poly-L-lactic acid and poly-D-lactic acid) (Mw = 150,000, dispersity 2.6)
A-14: Polylactic acid block copolymer obtained in Reference Example 21 (Mw = 17,000, dispersity 2.4)
A-15: Polylactic acid stereocomplex obtained in Reference Example 22 (mixture of poly-L-lactic acid and poly-D-lactic acid) (Mw = 170,000, dispersity 2.4)
A-16: Polylactic acid block copolymer obtained in Reference Example 23 (Mw = 190,000, degree of dispersion 2.2)
A-17: Polylactic acid block copolymer obtained in Reference Example 24 (Mw = 150,000, dispersity 1.8)
A-18: Polylactic acid block copolymer obtained in Reference Example 25 (Mw = 110,000, dispersity 1.7)
A-19: Polylactic acid stereocomplex obtained in Reference Example 26 (mixture of poly-L-lactic acid and poly-D-lactic acid) (Mw = 170,000, dispersity 1.7)
PLA3: Poly-L-lactic acid obtained in Reference Example 3 (Mw = 200,000, dispersity 1.7)
[Reference Example 8]
The PLA 3 obtained in Reference Example 3 and the PDA 1 obtained in Reference Example 4 were subjected to crystallization treatment at 110 ° C. for 2 hours in a nitrogen atmosphere before mixing. Subsequently, 50 parts by weight of crystallized PLA 3 is added from the resin supply port of the twin-screw extruder, and 50 parts by weight of PDA 1 is added from the side supply port provided at the portion of L / D = 30 described later. Melt kneading was performed. Here, the twin-screw extruder has a plasticized portion set at a temperature of 190 ° C. at a portion of L / D = 10 from the resin supply port, and is provided with a kneading disk at a portion of L / D = 30 to give shear. It has a structure that can be mixed under shearing as a possible screw. Using a twin screw extruder, PLA1 and PDA1 were melt-kneaded at a kneading temperature of 210 ° C. under reduced pressure to obtain polylactic acid stereocomplex (A-1). The polylactic acid stereocomplex (A-1) had a weight average molecular weight of 110,000, a dispersity of 2.7, a melting point of 211 ° C., and a stereocomplex formation rate of 100%.
[Reference Example 9]
The polylactic acid stereocomplex (A-1) obtained in Reference Example 8 was subjected to crystallization treatment at 110 ° C. for 1 hour in a nitrogen atmosphere, and then at a pressure of 60 Pa at 140 ° C. for 3 hours and at 150 ° C. for 3 hours. Solid phase polymerization was carried out at 160 ° C. for 18 hours to obtain a polylactic acid block copolymer (A-2). The polylactic acid block copolymer (A-2) had a weight average molecular weight of 130,000, a dispersity of 2.4, a melting point of 211 ° C., and a stereocomplex formation rate of 100%.
[Reference Example 10]
A polylactic acid stereocomplex (A-3) was obtained by melt kneading in the same manner as in Reference Example 8 except that 70 parts by weight of PLA3 and 30 parts by weight of PDA1 supplied to the twin screw extruder were used. The polylactic acid stereocomplex (A-3) had a weight average molecular weight of 130,000, a dispersity of 2.6, melting points of 214 ° C and 151 ° C double peaks, and a stereocomplex formation rate of 95%.
[Reference Example 11]
The polylactic acid stereocomplex (A-3) obtained in Reference Example 10 was subjected to solid phase polymerization in the same manner as in Reference Example 9 to obtain a polylactic acid block copolymer (A-4). The polylactic acid block copolymer (A-4) had a weight average molecular weight of 160,000, a dispersity of 2.3, melting points of double peaks of 215 ° C. and 171 ° C., and a stereocomplex formation rate of 97%.
[Reference Example 12]
A polylactic acid stereocomplex (A-5) is obtained by melt-kneading in the same manner as in Reference Example 10 except that PLA-1 is the poly-L-lactic acid to be melt-kneaded by a twin screw extruder and PDA1 is the poly-D-lactic acid. Got. The polylactic acid stereocomplex (A-5) had a weight average molecular weight of 40,000, a dispersity of 1.8, a melting point of 215 ° C., and a stereocomplex formation rate of 100%.
[Reference Example 13]
The polylactic acid stereocomplex (A-5) obtained in Reference Example 12 was subjected to solid phase polymerization in the same manner as in Reference Example 9 to obtain a polylactic acid block copolymer (A-6). The polylactic acid block copolymer (A-6) had a weight average molecular weight of 60,000, a dispersity of 1.6, a melting point of 215 ° C., and a stereocomplex formation rate of 100%.
[Reference Example 14]
A polylactic acid stereocomplex (A-7) is obtained by melt-kneading in the same manner as in Reference Example 10 except that PLA-2 is used as the poly-L-lactic acid to be melt-kneaded by a twin screw extruder and PDA1 is used as the poly-D-lactic acid. Got. The polylactic acid stereocomplex (A-7) had a weight average molecular weight of 100,000, a degree of dispersion of 2.2, melting points of 213 ° C. and 152 ° C. double peaks, and a stereo complex formation rate of 96%.
[Reference Example 15]
The polylactic acid stereocomplex (A-7) obtained in Reference Example 14 was subjected to solid phase polymerization in the same manner as in Reference Example 9 to obtain a polylactic acid block copolymer (A-8). The polylactic acid block copolymer (A-8) had a weight average molecular weight of 120,000, a dispersity of 2.0, melting points of 212 ° C. and 170 ° C. double peaks, and a stereocomplex formation rate of 98%.
[Reference Example 16]
A polylactic acid stereocomplex (A-9) was prepared by melt kneading in the same manner as in Reference Example 10 except that PLA-2 was used as the poly-L-lactic acid to be melt-kneaded by a twin screw extruder and PDA2 was used as the poly-D-lactic acid. Got. The polylactic acid stereocomplex (A-9) had a weight average molecular weight of 120,000, a dispersity of 2.4, melting points of 212 ° C and 160 ° C double peaks, and a stereocomplex formation rate of 93%.
[Reference Example 17]
The polylactic acid stereocomplex (A-9) obtained in Reference Example 16 was subjected to solid phase polymerization in the same manner as in Reference Example 9 to obtain a polylactic acid block copolymer (A-10). The polylactic acid block copolymer (A-10) had a weight average molecular weight of 140,000, a degree of dispersion of 2.2, melting points of 212 ° C. and 171 ° C. double peaks, and a stereocomplex formation rate of 95%.
[Reference Example 18]
A polylactic acid stereocomplex (A-11) is obtained by melt-kneading in the same manner as in Reference Example 10 except that PLA-2 is used as the poly-L-lactic acid to be melt-kneaded by a twin screw extruder and PDA3 is used as the poly-D-lactic acid. Got. The polylactic acid stereocomplex (A-11) had a weight average molecular weight of 130,000, a dispersity of 2.5, melting points of 210 ° C and 165 ° C double peaks, and a stereocomplex formation rate of 55%.
[Reference Example 19]
The polylactic acid stereocomplex (A-11) obtained in Reference Example 18 was subjected to solid phase polymerization in the same manner as in Reference Example 9 to obtain a polylactic acid block copolymer (A-12). The weight average molecular weight of the polylactic acid block copolymer (A-12) was 150,000, the degree of dispersion was 2.3, the melting points were 211 ° C. and 170 ° C. double peaks, and the stereocomplex formation rate was 63%.
[Reference Example 20]
A polylactic acid stereocomplex (A-13) is obtained by melt-kneading in the same manner as in Reference Example 10 except that PLA-3 is the poly-L-lactic acid to be melt-kneaded with a twin screw extruder and PDA2 is the poly-D-lactic acid. Got. The polylactic acid stereocomplex (A-13) had a weight average molecular weight of 150,000, a dispersity of 2.6, melting points of 211 ° C. and 161 ° C. double peaks, and a stereocomplex formation rate of 90%.
[Reference Example 21]
The polylactic acid stereocomplex (A-13) obtained in Reference Example 20 was subjected to solid phase polymerization in the same manner as in Reference Example 9 to obtain a polylactic acid block copolymer (A-14). The polylactic acid block copolymer (A-14) had a weight average molecular weight of 170,000, a degree of dispersion of 2.4, melting points of 212 ° C. and 171 ° C. double peaks, and a stereocomplex formation rate of 95%.
[Reference Example 22]
A polylactic acid stereocomplex (A-15) was prepared by melt kneading in the same manner as in Reference Example 10 except that PLA3 was used as the poly-L-lactic acid to be melt-kneaded by a twin screw extruder and PDA3 was used as the poly-D-lactic acid. Got. The polylactic acid stereocomplex (A-15) had a weight average molecular weight of 170,000, a dispersity of 2.4, melting points of 212 ° C. and 168 ° C. double peaks, and a stereocomplex formation rate of 60%.
[Reference Example 23]
The polylactic acid stereocomplex (A-15) obtained in Reference Example 22 was subjected to solid phase polymerization in the same manner as in Reference Example 9 to obtain a polylactic acid block copolymer (A-16). The polylactic acid block copolymer (A-16) had a weight average molecular weight of 190,000, a degree of dispersion of 2.2, melting points of 212 ° C. and 171 ° C. double peaks, and a stereocomplex formation rate of 67%.
[Reference Example 24]
After 100 parts of L-lactide and 0.15 part of ethylene glycol were uniformly dissolved in a reaction vessel equipped with a stirrer at 160 ° C. in a nitrogen atmosphere, 0.01 part of tin octylate was added and opened for 2 hours. A ring polymerization reaction was performed. After completion of the polymerization reaction, the reaction product was dissolved in chloroform and reprecipitated with stirring in methanol (5 times the amount of chloroform solution) to remove unreacted monomers to obtain poly-L-lactic acid (PLA4). . PLA4 had a weight average molecular weight of 80,000, a dispersity of 1.6, and a melting point of 168 ° C.

Next, 100 parts of the resulting PLA4 was dissolved in a reaction vessel equipped with a stirrer at 200 ° C. under a nitrogen atmosphere, 120 parts of D-lactide was added, and 0.01 part of octyl was added. After adding the acid tin, the polymerization reaction was carried out for 3 hours. The obtained reaction product was dissolved in chloroform, re-precipitated with stirring in methanol (5 times the amount of chloroform solution), unreacted monomers were removed, and D-lactic acid units were added to PLA4 consisting of L-lactic acid units. As a result, a polylactic acid block copolymer (A-17) having 3 segments to which segments consisting of The molecular weight of A-17 was 150,000, the degree of dispersion was 1.8, the melting point was a double peak of 208 ° C. and 169 ° C., and the stereocomplex formation rate was 95%. The ratio of the weight average molecular weight of the segment consisting of L-lactic acid units constituting the polylactic acid block copolymer A-17 to the weight average molecular weight of the segment consisting of D-lactic acid units was 2.7.
[Reference Example 25]
Kneading temperature of PLA3 (50 parts by weight) obtained in Reference Example 3 and PDA4 (50 parts by weight) obtained in Reference Example 7 with a batch type twin-screw kneader (labor plast mill) manufactured by Toyo Seiki Seisakusho Co., Ltd. Kneading was performed at 270 ° C., a kneading rotation speed of 120 rpm, and a kneading time of 10 minutes, and a polylactic acid block copolymer (A- 18) was obtained. A-18 had a molecular weight of 110,000, a dispersity of 1.7, a melting point of 211 ° C., and a stereocomplex formation rate of 100%.
[Reference Example 26]
PLA 3 obtained in Reference Example 3 and PDA 4 obtained in Reference Example 7 were melt kneaded in the same manner as in Reference Example 8 to obtain a polylactic acid stereocomplex (A-19). The polylactic acid stereocomplex (A-19) had a weight average molecular weight of 170,000, a dispersity of 1.7, melting points of 220 ° C. and 169 ° C. double peaks, and a stereocomplex formation rate of 55%.
(B) Polymer having a plurality of reactive groups per molecule B-1: Acrylic resin-based reactive compound: Epoxy group-containing styrene / acrylic acid ester copolymer ("JONCRYL" (registered trademark) manufactured by BASF Japan Ltd.) ADR-4368, Mw (PMMA equivalent) 8,000, epoxy equivalent 285 g / mol)
B-2: Polycarbodiimide (“Carbodilite” (registered trademark) HMV-8CA, manufactured by Nisshinbo Chemical Co., Ltd.), Mw (PMMA conversion) 3,000, carbodiimide equivalent 278 g / mol)
B-3: Polycarbodiimide (manufactured by Nisshinbo Chemical Co., Ltd. ““ Carbodilite ”(registered trademark) LA-1, Mw (PMMA conversion) 2,000, carbodiimide equivalent 247 g / mol)”
(C) Polyfunctional compound C-1: N, N′-di-2,6-diisopropylphenylcarbodiimide (“STABAXOL” (registered trademark), molecular weight 363, manufactured by Rhein Chemie Japan)
C-2: Hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., molecular weight 168)
C-3: 2,2 ′-(1,3-phenylene) bis (2-oxazoline) (manufactured by Mikuni Pharmaceutical Co., Ltd., molecular weight 216)
(D) Crystal nucleating agent D-1: Talc ("Microace" (registered trademark) P-6, manufactured by Nippon Talc Co., Ltd.)
D-2: Phosphate ester sodium salt (“ADEKA STAB” (registered trademark) NA-11, manufactured by ADEKA Corporation)
D-3: Phosphate ester aluminum salt (“ADEKA STAB” (registered trademark) NA-21, manufactured by ADEKA Corporation)
(Examples 1 to 18)
At various ratios shown in Tables 1 and 2, polylactic acid resin (A), polymer (B) having a plurality of reactive groups per molecule, and crystal nucleating agent (D) are dry-blended in advance, and then have a vent Melt kneading was performed with a twin screw extruder. As described above, the twin-screw extruder is provided with a plasticized portion set at a temperature of 225 ° C. at a portion of L / D = 10 from the resin supply port, and a kneading disk at a portion of L / D = 30 to apply shear. It has a structure that can be mixed under shearing as a screw capable of being melted and melt-kneaded at a kneading temperature of 220 ° C. under reduced pressure using this twin-screw extruder to obtain a pelletized polylactic acid resin composition It was.

Subsequently, the pellet of the polylactic acid resin composition was heated at 240 ° C. for 2 minutes to melt, and then pressed at a press temperature of 80 ° C. to produce a 1 mm thick press sheet. Next, the press sheet was heat-treated at 110 ° C. for 30 minutes under a nitrogen atmosphere to obtain sheet-like molded bodies for various measurements.

The physical properties of the polylactic acid resin composition and the molded body obtained by melt kneading are as shown in Tables 1 and 2.

In Examples 1 to 4, polylactic acid block copolymer A-2 was used as polylactic acid resin (A), and in Examples 5 to 8, polylactic acid block copolymer A-4 was used. Acrylic resin-based reactive compounds (B-1) having different addition amounts were added as a polymer (B) having a plurality of reactive groups per molecule, and melt kneading was performed. As a result, in both of the polylactic acid resin compositions (A-2) and (A-4), the amount of the acrylic resin-based reactive compound increased and the weight average molecular weight of the polylactic acid resin composition increased. Further, even after the reaction with the acrylic resin-based reactive compound, the polylactic acid resin composition had excellent crystallization characteristics with a temperature-falling crystallization temperature of 140 ° C. or higher and a crystallization enthalpy (ΔHc) of 40 J / g or higher. The heating loss at 240 ° C. for 30 minutes is less than 1%, and the melt viscosity ratio (MFR10 / MFR20) is within the range of 0.7 to 1.1. It was excellent. Furthermore, it was also found that the haze value of the molded product was less than 10%, and the transparency was excellent.

In Examples 9 to 14, the type of polylactic acid resin (A) was changed as shown in Table 1 to produce a polylactic acid resin composition. However, any polylactic acid resin could be used as an acrylic resin. As a result of the reaction with the system reactive compound (B-1), the increase in molecular weight and the retention stability during heating were shown as in Examples 1-8. Further, in terms of thermophysical properties, the temperature-falling crystallization temperature was 130 ° C. or higher, and it was found that the crystallization characteristics were excellent. Furthermore, the haze value of the molded product was less than 10% and excellent in transparency, and showed good mechanical properties in terms of tensile strength and storage elastic modulus.

In Example 15, a polylactic acid resin composition was prepared using polycarbodiimide (B-3) as a polymer (B) having a plurality of reactive groups per molecule, but by reaction with polycarbodiimide. Increased molecular weight and retention stability during heating were obtained.

In Examples 16 to 18, polylactic acid was added to the polylactic acid resin (A-4) by adding crystal nucleating agents D-1 to D-3 in addition to the acrylic resin reactive compound (B-1). Resin compositions were prepared, and any of the polylactic acid resin compositions showed an increase in molecular weight and a residence stability upon heating due to the reaction with the acrylic resin-based reactive compound (B-1). Further, in terms of thermophysical properties, since the temperature drop crystallization temperature was 130 ° C. or higher and the crystallization enthalpy (ΔHc) was 37 J / g or higher, it was found that heat resistance and crystallization characteristics were excellent. Further, the haze value of the molded product was 12% or less and excellent transparency, and showed good mechanical properties in terms of tensile strength and storage elastic modulus.
(Comparative Examples 1 to 23)
Polylactic acid resin (A), polymer (B) having a plurality of reactive groups per molecule, polyfunctional compound (C), and crystal nucleating agent (D) in various proportions shown in Table 3 and Table 4 After dry blending, melt kneading was performed in a twin screw extruder having a vent. For Comparative Examples 1 to 23, a polylactic acid resin composition and a molded body pelletized by the same method as in Examples 1 to 18 were obtained.

The physical properties of the polylactic acid resin composition and the molded product obtained by melt kneading are as shown in Table 3 and Table 4.

In Comparative Examples 1 to 4, the acrylic resin-based reactive compound (B-1) was added at 0.03 parts by weight and 2.5 parts by weight with respect to 100 parts by weight of the polylactic acid resin A-2 or A-4, respectively. Is. As a result, in Comparative Examples 1 and 3, the melt viscosity ratio (MFR10 / MFR20) was less than 0.5 even after the reaction with the acrylic resin-based reactive compound (B-1), compared with Examples 1 to 13. It was found that the residence stability during heating was low. On the other hand, in Comparative Examples 2 and 4, after the reaction with the acrylic resin-based reactive compound (B-1), the polylactic acid resin composition was gelled, and the melt viscosity ratio (MFR10 / MFR20) was 1 or more. . The polylactic acid resin compositions of Comparative Examples 2 and 4 could not be processed into molded articles due to gelation.

For Comparative Examples 5 to 15, polylactic acid resin compositions were prepared using polylactic acid stereocomplexes or polylactic acid block copolymers shown in Tables 3 and 4 as polylactic acid resin (A). As a result, in Comparative Examples 5 to 9, although the weight average molecular weight increased due to the reaction with the acrylic resin-based reactive compound (B-1), the loss on heating at 240 ° C. for 30 minutes was 3% or more. The melt viscosity ratio (MFR10 / MFR20) was 0.45 to 0,59, which was inferior in residence stability during heating as compared with the polylactic acid block copolymers shown in Examples 3, 7 and 9-11.

In Comparative Examples 10 to 15, in any case, an increase in the weight average molecular weight is observed by adding the acrylic resin-based reactive compound (B-1) as the polymer (B) having a plurality of reactive groups in one molecule. However, except for Comparative Example 12, the crystallization enthalpy ΔHc at the temperature-falling crystallization temperature was less than 10 J / g and the crystallization characteristics were poor. Further, in Comparative Examples 10, 12, 13, and 15 using a polylactic acid stereocomplex as the polylactic acid resin (A), the melt viscosity ratio (MFR10 / MFR20) is compared with the examples using the polylactic acid block copolymer. The result was low and the stability of the melt viscosity was poor. Regarding the physical properties of the molded products, the haze value of the molded products was 10% or more at any level of Comparative Examples 10 to 15, and the transparency was inferior to the Examples.

In Comparative Example 16, PLA3, which is homopolylactic acid, was used as the polylactic acid resin (A), but there was no formation of a stereocomplex, and no temperature drop crystallization temperature was observed, so heat resistance and crystallization characteristics were implemented. The results were inferior to the examples.

For Comparative Examples 17 to 19, polylactic acid resin compositions obtained by adding (C-1) to (C-3) as polyfunctional compounds (C) to the polylactic acid block copolymer (A-4) Was made. As a result, in any of Comparative Examples 17 to 19, the temperature-falling crystallization temperature was lower than 125 ° C. compared to Example 7 to which the acrylic resin-based reactive compound (B-1) was added, and the crystallization characteristics were inferior. all right. The haze values of these molded bodies were also 10% or more, and it was found that the transparency was inferior compared to the examples.

For Comparative Examples 20 to 22, the polylactic acid stereocomplex A-19 was used for the polylactic acid resin (A), and in addition to the acrylic resin reactive compound (B-1), the crystal nucleating agent (D-1) to ( A polylactic acid resin composition was prepared by adding D-3). As a result, the stereocomplex formation rate (Sc) of these polylactic acid resin compositions is less than 70%, the heat resistance is low compared to the examples, and the crystallization characteristics are also inferior as in the comparative examples 17-19. I understood. In particular, in Comparative Examples 21 and 22 in which a phosphoric acid metal ester was used in combination, the heat loss at 240 ° C. for 30 minutes was as high as 9% or more, and the residence stability was low. Further, the haze values of these molded products were also 10% or more, and the transparency was low as compared with the Examples.

In Comparative Example 23, polycarbodiimide (B-2) was added to polylactic acid resin (A-4) and melt-kneaded. The resulting polylactic acid resin composition had a temperature-falling crystallization temperature of 105. The crystallization enthalpy ΔHc was 5 J / g, and the crystallization characteristics were inferior to those of the examples.
(Examples 19 and 20)
The PLA 3 obtained in Reference Example 3 and the PDA 1 obtained in Reference Example 4 were subjected to crystallization treatment at 110 ° C. for 2 hours in a nitrogen atmosphere before mixing. Subsequently, PLA3, PDA1 and acrylic resin-based reactive compound (B-1) crystallized in the addition amounts shown in Table 3 were added from the resin supply port of the twin screw extruder, while crystallized PDA1 was described later. Melting and kneading were performed by adding from the side supply port provided in the portion of L / D = 30. Here, the twin-screw extruder has a plasticized portion set at a temperature of 190 ° C. at a portion of L / D = 10 from the resin supply port, and is provided with a kneading disk at a portion of L / D = 30 to give shear. It has a structure that can be mixed under shearing as a possible screw.

Further, the kneaded material kneaded as described above was subjected to crystallization treatment at 110 ° C. for 1 hour in a nitrogen atmosphere, followed by solid phase polymerization at 150 ° C. for 24 hours under a pressure of 60 Pa to obtain a polylactic acid resin composition. Obtained. For the polylactic acid resin composition, sheet-like molded bodies were produced in the same manner as in Examples 1 to 18.

Table 5 shows the physical properties of the polylactic acid resin composition and the molded body.
(Example 21)
The polylactic acid stereocomplex (A-3) obtained in Reference Example 10 and the acrylic resin-based reactive compound (B-1) were added from the resin supply port of the twin screw extruder and melt kneaded. The element configuration and temperature setting of the extruder are as described in Examples 19 and 20. Subsequently, the kneaded product after melt-kneading was subjected to solid phase polymerization by the method described in Examples 19 and 20. In addition, a sheet-like molded body was produced in the same manner as in Examples 1-18.
Table 5 shows the physical properties of the polylactic acid resin composition and the molded body.
(Examples 22 to 24)
The PLA 3 obtained in Reference Example 3, the PDA 4 obtained in Reference Example 7 and (A-4) obtained in Reference Example 11 were subjected to crystallization treatment at a temperature of 110 ° C. for 2 hours in a nitrogen atmosphere before mixing. It was.

For the preparation of the polylactic acid resin composition, the resin supply port of the twin screw extruder was added in advance with the polylactic acid block copolymer (A-4) and the acrylic resin-based reactive compound (B-1) added in the amounts shown in Table 5. The mixture was obtained by further adding and melt-kneading. Then, the polylactic acid resin composition was produced by adding the said mixture and PLA3 and PDA4 with the addition amount shown in Table 5 with respect to the resin supply port of a twin-screw extruder, and melt-kneading. In Examples 22 to 24, solid phase polymerization was not performed after kneading the polylactic acid resin composition. For the polylactic acid resin composition, sheet molded bodies were produced in the same manner as in Examples 1 to 18.

Table 5 shows the physical properties of the obtained polylactic acid resin composition and molded article.
(Comparative Examples 24 and 25)
A polylactic acid resin composition was prepared by preparing a kneaded material using a twin screw extruder in the same manner as in Examples 20 and 21. In Comparative Examples 24 and 25, the kneaded product was not subjected to solid phase polymerization. For the polylactic acid resin composition, sheet-like molded bodies were produced in the same manner as in Examples 1 to 19.

The physical properties of the obtained polylactic acid resin composition and the molded product are as shown in Table 5.

For Examples 19 and 20, PLA3, PDA1 and the acrylic resin-based reactive compound (B-1) were solid-phase polymerized after melt kneading all together without preparing a polylactic acid block copolymer in advance as a polylactic acid resin. The polylactic acid resin composition has a weight average molecular weight increased by reaction with the acrylic resin-based reactive compound (B-1), and the heat loss at 240 ° C. for 30 minutes is less than 1%, and the melt viscosity ratio (MFR10 / MFR20 ) Was also less than 0.5 to 1 and was excellent in retention stability during heating. In addition, regarding the thermophysical properties, the stereocomplex formation rate (Sc) was 90% or higher, and the heat resistance was high, and the temperature-falling crystallization temperature and crystallization enthalpy were also high, indicating that the crystallization characteristics were excellent. Further, the haze value of the molded product was also low, less than 10%, so that it was excellent in transparency and exhibited good mechanical properties in terms of tensile strength and storage elastic modulus.

In Example 21, unlike Examples 1 to 18, when the acrylic resin-based reactive compound (B-1) was added before solid-phase polymerization, the polylactic acid resin composition was acrylic as in Examples 1 to 18. The weight average molecular weight increased by the reaction with the resin-based reactive compound (B-1), and the melt viscosity ratio (MFR10 / MFR20) was 0.9, which was excellent in the retention stability during heating. Further, the temperature-falling crystallization temperature was 130 ° C. or higher and the crystallization enthalpy was as high as 35 J / g or more, so that it was found that the crystallization characteristics were excellent. Further, the haze value of the molded product was 9%, which was excellent in transparency, and exhibited good mechanical properties in terms of tensile strength and storage elastic modulus.

As for Examples 22 to 24, the physical properties of the obtained polylactic acid resin compositions were increased by the reaction with the acrylic resin-based reactive compound (B-1) as in Examples 1 to 18, and the melt was melted. The viscosity ratio (MFR10 / MFR20) was also 0.5 to less than 1, and the residence stability during heating was excellent. In addition, regarding the thermophysical properties, the stereocomplex formation rate (Sc) was 90% or higher, and the heat resistance was high, and the temperature-falling crystallization temperature and crystallization enthalpy were also high, indicating that the crystallization characteristics were excellent. Further, the haze value of the molded product was also low, less than 10%, so that it was excellent in transparency and exhibited good mechanical properties in terms of tensile strength and storage elastic modulus.

For Comparative Examples 24 and 25, PLA3, PDA1 and the acrylic resin-based reactive compound (B-1) were collectively melt-kneaded in the same manner as in Examples 19 and 20, but the solid-phase polymerization was not performed thereafter. The molecular weight was lower than in Examples 19 and 20, and it was found that the residence stability during heating was inferior from the results of weight loss on heating and melt viscosity ratio (MFR10 / MFR20). Further, regarding the thermal properties, in Comparative Example 24, the crystallization enthalpy at the time of temperature-fall crystallization was less than 25 J / g, and the crystallization characteristics were also inferior. Furthermore, the haze value of the molded body was as high as 10% or more, and the result was inferior in transparency as compared with Examples 19 and 20.

The polylactic acid resin composition of the present invention has improved mechanical properties, durability, stability during heating, and heat resistance due to the thickening effect of the polymer having a plurality of reactive groups in one molecule. Also, since it has excellent crystallization characteristics, it can be suitably used in fields that require heat resistance, crystallization characteristics, and retention stability during heating.

Claims

(A) 100 parts by weight of a polylactic acid block copolymer composed of a poly-L-lactic acid segment containing L-lactic acid as a main component and a poly-D-lactic acid segment containing D-lactic acid as a main component (B ) A polylactic acid resin composition comprising 0.05 to 2 parts by weight of a polymer having a plurality of reactive groups per molecule, and (B) a weight average of the polymers having a plurality of reactive groups per molecule Crystallization when the molecular weight is 1,000 to 15,000 and the polylactic acid resin composition is heated to 250 ° C. and kept at a constant temperature for 3 minutes and then cooled at a cooling rate of 20 ° C./min in DSC measurement. A polylactic acid resin composition having a calorific value of 10 J / g or more.
The polylactic acid resin composition according to claim 1, wherein the polymer (B) having a plurality of reactive groups per molecule is an epoxy group-containing acrylic resin-based reactive compound.
The polylactic acid resin composition according to claim 2, wherein the epoxy group-containing acrylic resin-based reactive compound has 2 to 30 epoxy groups per molecule.
The polylactic acid resin composition according to any one of claims 1 to 3, wherein a stereo complex formation rate (Sc) satisfies the following formula (1).
Sc = ΔHh / (ΔHl + ΔHh) × 100 ≧ 80 (1)
here,
ΔHh: Amount of heat (J / g) based on the stereocomplex crystal when the polylactic acid resin composition is heated at a rate of temperature increase of 20 ° C./min in the DSC measurement.
ΔHl: Calorie (J / g) based on crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal when heated at a rate of temperature increase of 20 ° C./min in DSC measurement of polylactic acid resin composition
The ratio (MFR10 / MFR20) of the melt flow rate (MFR10) after 10 minutes and the melt flow rate (MFR20) after 20 minutes of the polylactic acid resin composition at 230 ° C. and 21.2 N load condition is 0.5 or more and 2 or less. The polylactic acid resin composition according to any one of claims 1 to 4, wherein
In DSC measurement, the polylactic acid resin composition was heated to 250 ° C. and kept at a constant temperature for 3 minutes, and then the temperature-decreasing crystallization temperature of the polylactic acid resin composition was 130 ° C. or higher when the temperature was lowered at a cooling rate of 20 ° C./min. The polylactic acid resin composition according to any one of claims 1 to 5, wherein
The (A) polylactic acid block copolymer is prepared by mixing poly-L-lactic acid or poly-D-lactic acid under the conditions of the following combination 1 and / or the following combination 2 to form a stereocomplex with a weight average molecular weight of 90,000 or more. The polylactic acid resin according to any one of claims 1 to 6, wherein the polylactic acid resin is obtained by obtaining a mixture having a rate (Sc) satisfying the following formula (2) and then solid-phase polymerization at a temperature lower than the melting point of the mixture. Composition.
(Combination 1) The weight average molecular weight of either poly-L-lactic acid or poly-D-lactic acid is 60,000 to 300,000, and the other weight average molecular weight is 10,000 to 100,000 (Combination 2). The ratio of the weight average molecular weight of poly-L-lactic acid to the weight average molecular weight of poly-D-lactic acid is 2 or more and less than 30 Sc = ΔHh / (ΔHl + ΔHh) × 100> 60 (2)
here,
ΔHh: calorific value (J / g) based on stereocomplex crystals when the temperature is raised at a rate of temperature rise of 20 ° C./min in DSC measurement of a mixture of poly-L-lactic acid and poly-D-lactic acid
ΔHl: Crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal when heated at a rate of temperature increase of 20 ° C./min in DSC measurement of a mixture of poly-L-lactic acid and poly-D-lactic acid Heat quantity based on (J / g)
The (A) polylactic acid block copolymer is prepared by mixing poly-L-lactic acid or poly-D-lactic acid under the conditions of the following combination 3 and / or the following combination 4 to form a stereocomplex with a weight average molecular weight of 90,000 or more. The polylactic acid resin according to any one of claims 1 to 6, wherein the polylactic acid resin is obtained by obtaining a mixture having a rate (Sc) satisfying the following formula (2) and then solid-phase polymerization at a temperature lower than the melting point of the mixture. Composition.
(Combination 3) The weight average molecular weight of either poly-L-lactic acid or poly-D-lactic acid is 120,000 to 300,000, and the other weight average molecular weight is 30,000 to 100,000 (Combination 4) The ratio of the weight average molecular weight of poly-L-lactic acid to the weight average molecular weight of poly-D-lactic acid is 2 or more and less than 30.
Sc = ΔHh / (ΔHl + ΔHh) × 100> 60 (2)
here,
ΔHh: calorific value (J / g) based on stereocomplex crystals when the temperature is raised at a rate of temperature rise of 20 ° C./min in DSC measurement of a mixture of poly-L-lactic acid and poly-D-lactic acid
ΔHl: Crystal melting of poly-L-lactic acid single crystal and poly-D-lactic acid single crystal when heated at a rate of temperature increase of 20 ° C./min in DSC measurement of a mixture of poly-L-lactic acid and poly-D-lactic acid Heat quantity based on (J / g)
The polylactic acid resin composition according to any one of claims 1 to 8, wherein the polylactic acid resin composition has a weight average molecular weight of 100,000 to 500,000.
A polylactic acid resin composition further comprising (b) poly-L-lactic acid and / or (c) poly-D-lactic acid in addition to the polylactic acid resin composition according to any one of claims 1 to 9.
A molded body comprising the polylactic acid resin composition according to any one of claims 1 to 10.
The molded product according to claim 11, wherein the molded product represented by the following formula (3) has a relative crystallinity of 90% or more and a molded product having a thickness of 1 mm has a haze value of 10% or less.
Relative crystallinity = [(ΔHm−ΔHc) / ΔHm] × 100 (3)
here,
ΔHm: Crystal melting enthalpy of compact (J / g)
ΔHc: Crystallization enthalpy at elevated temperature of the compact (J / g)
Poly-L-lactic acid and poly-L-lactic acid or poly-D-lactic acid having a weight average molecular weight of 60,000 to 300,000 and the other weight average molecular weight of 10,000 to 100,000 Mixing poly-L-lactic acid and poly-D-lactic acid in which the ratio of the weight average molecular weight of D-lactic acid or poly-L-lactic acid and the weight average molecular weight of poly-D-lactic acid is 2 or more and less than 30;
After solid phase polymerization at a temperature below the melting point of the mixture,
The method for producing a polylactic acid resin composition according to any one of claims 1 to 10, wherein (B) a polymer having a plurality of reactive groups is added to one molecule.
Poly-L-lactic acid and poly-L-lactic acid or poly-D-lactic acid having a weight average molecular weight of 60,000 to 300,000 and the other weight average molecular weight of 10,000 to 100,000 After mixing poly-L-lactic acid and poly-D-lactic acid in which the ratio of the weight average molecular weight of D-lactic acid or poly-L-lactic acid and the weight average molecular weight of poly-D-lactic acid is 2 or more and less than 30,
(B) blending a polymer having a plurality of reactive groups in one molecule,
The method for producing a polylactic acid resin composition according to any one of claims 1 to 10, wherein solid-phase polymerization is performed at a temperature lower than the melting point of the mixture.
Poly-L-lactic acid and poly-L-lactic acid or poly-D-lactic acid having a weight average molecular weight of 60,000 to 300,000 and the other weight average molecular weight of 10,000 to 100,000 D-lactic acid and (B) a polymer having a plurality of reactive groups per molecule are mixed, or the ratio of the weight average molecular weight of poly-L-lactic acid to the weight average molecular weight of poly-D-lactic acid is 2 to 30 Less than poly-L-lactic acid and poly-D-lactic acid and (B) a polymer having a plurality of reactive groups per molecule,
The method for producing a polylactic acid resin composition according to any one of claims 1 to 10, wherein solid-phase polymerization is performed at a temperature lower than the melting point of the mixture.