JP5299637B2 - Polylactic acid-based stereocomplex - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid-based stereocomplex body which is further improved in heat and impact resistances and flexibility, contains little residual lactide and ensures a small amount of lactide produced as a by-product in a molding step, while having properties such as biodegradability, safety and crystallinity which a conventional polylactic acid-based polymer has. <P>SOLUTION: The polylactic acid-based stereocomplex body is a mixture of a block copolymer having a segment consisting mainly of L-lactic acid units and copolymerized with an organophosphorus compound represented by a specific structure at both ends of a segment consisting mainly of aliphatic carbonate units, and a block copolymer having a segment consisting mainly of D-lactic acid units and copolymerized with an organophosphorus compound represented by general formula 1 at both ends of a segment consisting mainly of aliphatic carbonate units. In the formula, R<SB>1</SB>, R<SB>2</SB>, R<SB>3</SB>, and R<SB>4</SB>denote hydrogen or an alkyl group, and each may be same or different. (n) is an integer of at least one. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a polylactic acid-based stereocomplex body in which a specific organic phosphorus compound is copolymerized in a resin. While the polylactic acid-based stereocomplex of the present invention has the properties of conventional polylactic acid-based polymers such as biodegradability, safety, and crystallinity, it has improved heat resistance, impact resistance, and flexibility. The residual lactide is small, and the amount of lactide by-product is small in the molding process. Therefore, the molded body using the polylactic acid-based stereocomplex body has little deterioration of the resin accompanying the generation of the organic acid, and is excellent in storage stability, long-term heat resistance, and long-term durability.

  Many of the polymer materials currently in general use depend on petroleum resources. However, from the viewpoint of resource depletion or protection of the natural environment, polylactic acid-based polymers are biodegradable, renewable bio-derived plastics. It is getting attention. Polylactic acid-based polymers have a relatively high melting point of around 170 ° C. and excellent transparency, and thus have been put into practical use for packaging materials and other plastic molded articles that make use of transparency. Polylactic acid-based polymers are injection-molded products that are hard and brittle, but the fibers and films that have been molecularly oriented by stretching have sufficient strength, so in addition to products that do not require so much mechanical strength as described above, It is also being used in engineering applications such as automobiles and home appliances that require long life and high performance.

  As one of such polylactic acid-based polymers, for example, JP-A-9-40761 (Patent Document 1) discloses a crystalline segment (A) comprising a substantial homopolymer of poly L-lactic acid or poly D-lactic acid. And a polylactic acid block copolymer in which an amorphous segment (B) mainly composed of L-lactic acid and D-lactic acid is bonded. Patent Document 1 describes that such a polylactic acid block copolymer is excellent in crystallinity, heat resistance, flexibility and toughness.

  In addition, poly-L-lactic acid and poly-D-lactic acid, which are enantiomers, are physically mixed to have a crystal structure completely different from that of poly-L-lactic acid and poly-D-lactic acid. It is known that a stereocomplex body having improved properties can be obtained. In recent years, a stereocomplex body using polylactic acid has been improved.

  For example, in JP-A-2005-187626 (Patent Document 2), a polylactic acid stereoblock copolymer containing an L-lactic acid segment and a D-lactic acid segment, poly L-lactic acid, and poly D-lactic acid are mixed, A method for producing a polylactic acid stereocomplex body in which a stereocomplex is formed in the mixture is disclosed. Patent Document 2 discloses that the production method uses only D-lactic acid and L-lactic acid as raw material compounds, and is excellent in mechanical strength, heat resistance, thermal stability, excellent in transparency, and low irritation. It was disclosed that a polylactic acid stereocomplex having excellent safety and biodegradability could be produced.

  Further, for example, Japanese Patent Application Laid-Open No. 2007-100104 (Patent Document 3) describes a segment composed of an L-lactic acid unit and a segment composed of a D-lactic acid unit, having a melting point of 200 ° C. or higher and a polylactic acid block. A lactic acid block copolymer having a segment length satisfying Y <X / 2 with respect to the weight average molecular weight X of the polymer and the maximum weight average molecular weight Y of one unit of segment is disclosed. According to Patent Document 3, it is described that the polyblock copolymer forms a polylactic acid stereocomplex that can maintain a high melting point and increase the crystallization speed regardless of the thermal melting history. .

However, polylactic acid, which is a conventional polymer of lactic acid or lactide, or a copolymer of lactic acid or lactide and another monomer is difficult to say that it has sufficient performance in processability and heat resistance. In addition, polylactic acid has problems such as its degradability is too fast and difficult to use as a general-purpose resin, except for special applications, and it is an important development issue to suppress decomposition, especially to improve storage stability. Yes.

Similarly, the resin is greatly deteriorated during the molding process, and the produced molded body is subjected to severe strength deterioration before use. The main cause is that the lactide component remaining at the time of polymerization and / or the lactide component generated at the time of the molding process is decomposed by moisture in the atmosphere, becomes an organic acid, and acts on the breakage of the polymer chain. In contrast, a lactic acid-based polyester with a small amount of residual lactide is remarkably suppressed in decomposition and has excellent storage stability and molding processability.

In addition, it is considered that the polylactic acid resin causes a back-biting reaction at the end of polylactic acid in the heating step, thereby producing lactide. Therefore, in the molded body using the polylactic acid resin, the lactide generated in the production process remains in the product and deteriorates durability, storage stability, heat resistance, and adhesiveness.

Regarding the method of removing lactide from lactic acid-based polyester, a method of extracting with a solvent and a method of dissolving a polymer in a good solvent and precipitating it in a poor solvent are known in laboratory experiments. In manufacturing on an industrial scale, Patent Document 4 discloses a method using a twin screw extruder, and Patent Document 5 discloses a method in which lactide is volatilized and removed in a pot in which a strand is decompressed.

Patent Document 6 discloses a method for removing a catalyst from polylactic acid produced from lactic acid in the presence of a solvent. In this method, a hydrophilic organic solvent and a weak acid are added to polylactic acid dissolved in a solvent to remove a catalyst component.

Patent Documents 7 and 8 disclose a method of adding a phosphoric acid compound or a phosphorous acid compound after the polymerization reaction to deactivate the catalyst. By adding a phosphoric acid compound at the end of the polymerization reaction, the catalyst can be deactivated and polylactic acid with little residual lactide can be obtained.

Patent Document 9 discloses a method of adding an alkyl phosphate and / or an alkyl phosphonate after the polymerization reaction to deactivate the catalyst.

Although the polylactic acid resin obtained by these methods has a small amount of residual lactide, there is a difference in the effect. For example, the present inventors have verified the polylactic acid resin obtained by the method of Patent Document 9 Although the amount of lactide was reduced from the conventional one, the reduction amount was small. Even if the lactide prepared by these methods is sufficiently reduced, a molded product prepared using the resin may deteriorate in heat resistance, storage stability and heat resistance when stored for a long period of time. For example, although the polylactic acid resin obtained by the methods of Patent Documents 4 and 5 has a small amount of residual lactide, since lactide is produced in the process of producing a molded product, it is finally decomposed to produce an organic acid. When the resin composition produced in a conventional manner is stored for a long period of time, the polylactic acid molecular chain may be broken to deteriorate durability, heat resistance, and the like.

Japanese Patent Laid-Open No. 9-40761 JP 2005-187626 A JP 2007-100104 A European Patent No. 532154 JP-A-5-93050 JP-A-6-116381 JP-A-7-228664 Japanese Patent No. 2886071 Japanese Patent No. 3513972

  The object of the present invention is to improve the heat resistance, impact resistance, and flexibility while having the characteristics of conventional polylactic acid polymers such as biodegradability, safety, and crystallinity. In addition to obtaining a polylactic acid-based polymer that is difficult to produce lactide even when processed with it, and satisfying the long-term heat resistance and long-term durability of molded products produced using them. It is to be.

  The polylactic acid-based stereocomplex body of the present invention is a block having a segment composed mainly of L-lactic acid units at both ends of a segment mainly containing an aliphatic carbonate unit and copolymerized with an organic phosphorus compound represented by the general formula 1. A mixture of a copolymer and a block copolymer having a segment mainly composed of D-lactic acid units at both ends of a segment mainly containing an aliphatic carbonate unit and having an organic phosphorus compound represented by the general formula 1 copolymerized It is characterized by being.

(General formula 1)

(Wherein R ₁ , R ₂ , R ₃ and R ₄ represent hydrogen or an alkyl group, and may be the same or different. N represents an integer of 1 or more.)

  In the polylactic acid-based stereocomplex of the present invention, a block having segments in which an organophosphorus compound represented by the general formula 1 is copolymerized mainly at both ends of a segment mainly containing an aliphatic carbonate unit. Mixing of a copolymer with a block copolymer having a segment mainly composed of D-lactic acid units at both ends of a segment mainly containing an aliphatic carbonate unit and having an organic phosphorus compound represented by the general formula 1 copolymerized The ratio is preferably in the range of 1: 0.5 to 2.0.

In the polylactic acid-based stereocomplex of the present invention, in the segment mainly composed of L-lactic acid units and copolymerized with the organic phosphorus compound represented by the general formula 1, the organic phosphorus compound is R ₁ , R ₂ and In the segment bonded with at least one position of R ₃ and composed mainly of the D-lactic acid unit, and the organic phosphorus compound represented by the general formula 1 is copolymerized, the organic phosphorus compound is R ₁ , R ₂ and it is preferably bonded at least one location of R _3.

In the polylactic acid-based stereocomplex of the present invention, in the segment mainly composed of L-lactic acid units and the organic phosphorus compound represented by the general formula 1 is copolymerized, the organic phosphorus compound is bonded by R ₃ , In the segment composed mainly of D-lactic acid units and copolymerized with the organophosphorus compound represented by the general formula 1, the organophosphorus compound is preferably bonded by R ₃ .

In the polylactic acid-based stereocomplex body of the present invention, it is derived from the phosphorus element (a1) and the polymerization catalyst in the segment mainly composed of L-lactic acid units and copolymerized with the organic phosphorus compound represented by the general formula 1. The phosphorus element (a2) in the segment in which the molar ratio of the metal element (b1) satisfies the following relationship and is mainly composed of the D-lactic acid unit and the organic phosphorus compound represented by the general formula 1 is copolymerized It is preferable that the molar ratio of the polymerization catalyst-derived metal element (b2) satisfies the following relationship.
30 ≧ (a1) / (b1) ≧ 1
30 ≧ (a2) / (b2) ≧ 1

  Moreover, it is preferable that the aliphatic carbonate unit in the polylactic acid-type stereocomplex body of this invention is a polycarbonate diol which consists of a 1, 6- hexanediol residue.

  The segment mainly containing aliphatic carbonate units in the polylactic acid-based stereocomplex of the present invention preferably has a number average molecular weight of 2000 or more.

  While the polylactic acid-based stereocomplex of the present invention has the properties of conventional polylactic acid-based polymers such as biodegradability, safety, and crystallinity, it has improved heat resistance, impact resistance, and flexibility. The residual lactide is small, and the amount of lactide by-product is small in the molding process. Therefore, the molded body using the polylactic acid-based stereocomplex body has little deterioration of the resin accompanying the generation of the organic acid, and is excellent in storage stability, long-term heat resistance, and long-term durability.

  The polylactic acid-based stereocomplex body of the present invention is mainly composed of L-lactic acid units at both ends of a segment mainly containing aliphatic carbonate units (referred to as “C segment” in the present specification), and is represented by the general formula 1. A block copolymer having a structure (hereinafter referred to as “A segment”) in which an organic phosphorus compound is copolymerized (hereinafter referred to as “A-C”). -A block copolymer ") and an organic phosphorus compound represented by the general formula 1 is mainly composed of D-lactic acid units at both ends of a segment mainly containing aliphatic carbonate units (C segment). Block copolymer having a structure having a segment (referred to herein as “B segment”) A the copolymer mixture of "B-C-B block copolymer" as referred.). Prior to the description of the polylactic acid-based stereocomplex body of the present invention, first, the A-C-A block copolymer and the B-C-B block copolymer in the present invention will be described in detail.

[1] A-C-A block copolymer The A segment, which is a segment mainly composed of L-lactic acid units in the A-C-A block copolymer, is a polymer of two or more L-lactic acids. The L-lactic acid mainly comprising the A segment preferably has an optical purity of 95% ee (enantio excess) or more, and more preferably 99% ee or more. This is because, when the optical purity of L-lactic acid mainly constituting the A segment is less than 95% ee, the crystallinity of polylactic acid is low and the melting point tends to decrease. The optical purity refers to a value measured by, for example, a HPLC (High Performance Liquid Chromatography) method using an optical resolution column.

  In general, polylactic acid is polymerized by direct polymerization of lactic acid (dehydration condensation), condensation of lactic acid esters (methyl ester, ethyl ester, etc.) (dealcoholization), and ring-opening polymerization of lactide, which is a cyclic dimer of lactic acid. . Among them, the direct polymerization of lactic acid (dehydration polymerization) and the condensation method of lactic acid esters tend to cause random copolymerization, and block copolymerization is often extremely difficult. Therefore, the A-C-A block copolymer of the present invention The A segment is preferably polymerized by ring-opening polymerization of LL-lactide (L-lactide), which is a dimer of L-lactic acid.

  The C segment, which is a segment mainly containing aliphatic carbonate units in the A-C-A block copolymer, contains two or more polymers of aliphatic diols. Here, the aliphatic carbonate is preferably composed mainly of an aliphatic diol residue having 2 to 12 carbon atoms. Examples of these aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2- Dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol Among them, an aliphatic polycarbonate diol composed of 1,6-hexanediol is preferable because of its low melting point and low glass transition temperature. Of course, the C segment in the present invention may contain two or more aliphatic carbonate units.

  As long as the C segment in the present invention mainly contains the above-described aliphatic carbonate unit, a component other than the aliphatic carbonate unit may be copolymerized. The phrase “mainly containing aliphatic carbonate units” means that 70 wt% or more (preferably 80 wt% or more) of the C segment is an aliphatic carbonate unit. The purpose of copolymerizing other components with the C segment is as follows: hydrophilicity, water repellency, dyeability, antioxidant property, flexibility, elastic recovery, impact resistance, heat resistance, gas barrier property, glass transition temperature, decomposability , Improvement in smoothness, releasability, moldability, etc., cost reduction, and the like.

  Examples of the component copolymerizable with the aliphatic carbonate unit include (1) hydroxy acids such as glycolic acid, hydroxybutylcarboxylic acid and hydroxybenzoic acid, (2) aliphatic lactones such as glycolide, butyrolactone and caprolactone, (3) Diols other than polycarbonate diols having 2 to 20 carbon atoms such as ethylene glycol, propylene glycol, butanediol, hexanediol, dimer diol, hydrogenated dimer diol, (4) succinic acid, adipic acid, sebacic acid, decanedicarboxylic acid, phthalate Acids, isophthalic acid, sulfoisophthalic acid (alkali metal salts), terephthalic acid, naphthalene dicarboxylic acid, dimer acid, hydrogenated dimer acid, and other fatty acids and aromatic dicarboxylic acids, and polymers or oligomers having a hydroxyl group at the molecular end Examples of the mer include (5) polyalkylene ethers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol and copolymers thereof, oligomers, and (6) polyorganosiloxanes such as dimethylsiloxane, diethylsiloxane, and diphenylsiloxane. .

  For example, a compound having a sulfone group or an ether bond is used for improving hydrophilicity and degradability, a silicon compound is used for improving water repellency, and a compound having a glass transition point of room temperature or less is used for improving flexibility and toughness (polyalkylene lactam). , Polyalkylene alkylates, polyalkylene ethers, polyalkylene carbonates, and the like), and those having a high glass transition point (such as aromatic compounds) are effective for improving heat resistance.

The C segment in the A-C-A block copolymer preferably has a number average molecular weight (Mn) of 2000 or more. This is because the A-C-A block copolymer having excellent flexibility can be realized when the number average molecular weight of the C segment is 2000 or more. The number average molecular weight of the C segment is preferably as large as possible, but is preferably 50000 or less. From the viewpoint of compatibility, the number average molecular weight of the C segment is more preferably in the range of 10,000 to 20,000. The number average molecular weight of the C segment refers to a value calculated from an integrated value measured by, for example, 500 MHz ¹ H NMR (ARX500 (manufactured by Brucker)).

The A segment in the A-C-A block copolymer is a so-called hard segment, and the more it is, the higher the melting point and softening point, and the better the heat resistance. Conversely, the C segment in the A-C-A block copolymer is a so-called soft segment, and the more C segments, the better the flexibility, impact resistance, elastic recovery, and the like. The ratio of the A segment monomer unit to the C segment monomer unit in the A-C-A block copolymer is not particularly limited, but is 30:70 to 95: 5 (mass ratio). It is preferable to be within the range of 40:60 to 90:10 (mass ratio). This is because when the ratio of the monomer unit of the C segment to the monomer unit of the A segment is less than 5, improvement in impact resistance and flexibility tends to be insufficient, and the unit of the C segment This is because when the ratio of the monomer unit of the A segment to the monomer unit exceeds 70, polylactic acid has low crystallinity and heat resistance tends to be insufficient. In addition, the ratio of the monomer unit of the A segment to the monomer unit of the C segment in the A-C-A block copolymer was measured using, for example, 500 MHz ¹ H NMR (ARX500 (manufactured by Brucker)). It can be calculated from the data.

  The overall number average molecular weight (Mn) of the A-C-A block copolymer is not particularly limited, but is preferably in the range of 6000 to 500,000, and more preferably in the range of 15,000 to 200,000. When the overall number average molecular weight of the A-C-A block copolymer is less than 6000, sufficient mechanical properties tend not to be exhibited. The total number average molecular weight of the A-C-A block copolymer was determined by connecting two TSKgel SuperHZM-N (TOSOH) to the column and RID-10A (SHIMADZU) to the suggested refractive index detector. It can be measured by the GPC method using

  The A-C-A block copolymer is not particularly limited in the dispersity (PDI), but is preferably in the range of 1.0 to 3.0. When the degree of dispersion of the A-C-A block copolymer exceeds 3.0, the molecular weight distribution is large and the physical properties of the polymer tend not to be uniform. In addition, the dispersion degree of an ACA block copolymer can be measured by GPC method similarly to the number average molecular weight mentioned above.

  Moreover, it is preferable that melting | fusing point (Tm) of an ACA block copolymer exists in the range of 130-180 degreeC. When the melting point of the A-C-A block copolymer is less than 130 ° C., the crystallinity of the polymer is low and sufficient heat resistance tends not to be obtained. The melting point of the A-C-A block copolymer can be measured, for example, by DSC analysis using DSC-50 (manufactured by Shimadzu) and increasing the temperature at 10 ° C./min.

  The A-C-A block copolymer in the present invention is not particularly limited as to its production method. For example, in the following reaction scheme, as a suitable example, polyhexamethylene carbonate diol (PHMC) and L An example is shown in which lactide is copolymerized to synthesize an ACA (PLLA-PHMC-PLLA) block copolymer. In the following reaction scheme, enantiomers are not shown. In addition, if necessary, the so-called “joint” structure that has been widely used in the art, such as an ester bond, a urethane bond, and an amide bond, is particularly limited for the A-C-A block copolymer. It can employ | adopt suitably, without.

  The reaction conditions for the copolymerization reaction are not particularly limited, but conditions for reacting within a range of 120 to 200 ° C. for 1 to 4 hours are preferable. The above reaction scheme shows an example in which PHMC and L-lactide are reacted at 180 ° C. for 1.5 hours to produce an ACA (PLLA-PHMC-PLLA) block copolymer.

[2] B-C-B block copolymer The B-segment, which is a segment mainly composed of D-lactic acid units in the B-C-B block copolymer, is a polymer of two or more D-lactic acids. The D-lactic acid mainly constituting the B segment preferably has an optical purity of 95% ee or more, and more preferably 99% ee or more. This is because, when the optical purity of D-lactic acid mainly constituting the B segment is less than 95% ee, the crystallinity of polylactic acid is low and the melting point tends to decrease. The optical purity of D-lactic acid refers to a value measured by the same method as the optical purity of L-lactic acid described above.

  Similarly to the A segment of the A-C-A block copolymer, the B segment of the B-C-B block copolymer in the present invention is a dimer of D-lactic acid, DD-lactide (D-lactide). It is preferable to obtain by ring-opening polymerization.

  The C segment, which is a segment mainly containing aliphatic carbonate units in the B-C-B block copolymer, includes the same aliphatic carbonate as described above for the C segment in the A-C-A block copolymer, For the same reason, an aliphatic polycarbonate diol composed of 1,6-hexanediol is preferred. In addition, the C segment in the B—C—B block copolymer may be copolymerized with components other than the aliphatic carbonate unit, like the C segment in the A—C—A block copolymer. The number average molecular weight (Mn) of the C segment in the B—C—B block copolymer is in the range of 2000 to 50000 for the same reason as described above for the C segment in the A—C—A block copolymer. It is preferable to be within.

  Also in the B—C—B block copolymer, the B segment is a so-called hard segment, and the more it is, the higher the melting point and softening point, and the better the heat resistance. Moreover, the C segment in the B—C—B block copolymer is a so-called soft segment, and the more the C segment, the better the flexibility, impact resistance, elastic recovery, and the like. The ratio of the B segment monomer unit to the C segment monomer unit in the B-C-B block copolymer is not particularly limited, but is 30:70 to 95: 5 (mass ratio). It is preferable to be within the range of 40:60 to 90:10 (mass ratio). This is because when the ratio of the monomer unit of the C segment to the monomer unit of the B segment is less than 5, improvement in impact resistance and flexibility tends to be insufficient, and the unit of the C segment This is because when the ratio of the monomer unit of the B segment to the monomer unit exceeds 70, polylactic acid tends to have low crystallinity and insufficient heat resistance. In addition, the ratio of the monomer unit of the B segment to the monomer unit of the C segment in the B—C—B block copolymer is the same as that of the monomer unit of the A segment in the A—C—A block copolymer. The ratio of the C segment to the monomer unit can be calculated by the same method as described above.

  The overall number average molecular weight (Mn) of the B—C—B block copolymer is not particularly limited, but is preferably in the range of 6000 to 500,000, and more preferably in the range of 15,000 to 200,000. . This is because when the number average molecular weight of the B—C—B block copolymer is less than 6000, sufficient mechanical properties tend not to be exhibited. The number average molecular weight of the B—C—B block copolymer can be measured by the GPC method in the same manner as the A—C—A block copolymer.

  Further, the dispersity (PDI) of the B—C—B block copolymer is not particularly limited, but is preferably in the range of 1.0 to 3.0. When the degree of dispersion of the B—C—B block copolymer exceeds 3.0, the molecular weight distribution is large and the physical properties of the polymer tend not to be uniform. The number average molecular weight of the B—C—B block copolymer can be measured by the GPC method in the same manner as the A—C—A block copolymer.

  The melting point (Tm) of the B—C—B block copolymer is preferably in the range of 130 to 180 ° C. When the melting point of the B—C—B block copolymer is less than 130 ° C., the crystallinity of the polymer is low and sufficient heat resistance tends not to be obtained. The melting point of the B—C—B block copolymer can be measured by the same method as described above for the A—C—A block copolymer.

  The production method of the B—C—B block copolymer in the present invention is not particularly limited, but can be suitably produced in the same manner as described above for the A—C—A block copolymer. it can. That is, in the following reaction scheme, as a suitable example, polyhexamethylene carbonate diol (PHMC) is copolymerized with D-lactide to synthesize a B—C—B (PDLA-PHMC-PDLA) block copolymer. An example is shown. In the following reaction scheme, enantiomers are not shown. Further, as required, the so-called “joint” structure that has been widely used in the art, such as an ester bond, a urethane bond, and an amide bond, is particularly limited to the B—C—B block copolymer. It can employ | adopt suitably, without.

  The reaction conditions for the copolymerization reaction are not particularly limited, but conditions for reacting within a range of 120 to 200 ° C. for 1 to 4 hours are preferable. The above reaction scheme shows an example of producing a B—C—B (PDLA-PHMC-PDLA) block copolymer by reacting PHMC with D-lactide at 180 ° C. for 1.5 hours.

  The A-C-A block copolymer and B-C-B block copolymer of the present invention are represented by the general formula 1 at the time of production for the purpose of reducing the amount of lactide by-produced during and after production. Add organophosphorus compound. The timing of adding the organophosphorus compound is not particularly limited, but in order to reduce the amount of remaining lactide more effectively, it is preferable to add the organophosphorus compound before the completion of the ring-opening polymerization, and the ring-opening polymerization starts. It is more preferable to add it before carrying out.

  The polymerization catalyst used in the production of the A-C-A block copolymer and B-C-B block copolymer of the present invention is not particularly limited, and tin compounds such as tin octylate and tin dibutylate, aluminum Polylactic acid polymerization, including aluminum compounds such as acetylacetonate and aluminum acetate, titanium compounds such as tetraisopropyl titanate and tetrabutyl titanate, zirconium compounds such as zirconium isoprooxide, and antimony compounds such as antimony trioxide. And conventionally known catalysts.

  The optimum amount of the polymerization catalyst may be appropriately adjusted depending on the catalyst type. For example, when tin octoate is used, 0.005 to 0.5 mol%, preferably 0.01 to 0, relative to 100 mol% of the raw material lactide. It is possible to produce an A-C-A block copolymer and a B-C-B block copolymer by heating and polymerizing usually using 0.5 mol% of catalyst for 0.5 to 10 hours.

  The organophosphorus compound used in the production of the A-C-A block copolymer and B-C-B block copolymer of the present invention is represented by the general formula 1.

(General formula 1)

R ₁ , R ₂ , R _{3 and} R ₄ represent hydrogen or an alkyl group, and may be the same or different. In particular, among R ₁ , R ₂ , and R ₃ , when the ratio of these hydrogens is increased, the polymerization catalyst is deactivated, and therefore, when these phosphorus compounds are added before ring-opening polymerization or in the early stage of ring-opening polymerization, polymerization failure occurs and molecular weight Tends to be difficult to increase. Therefore, in producing the aliphatic polyester resin of the present invention, it is preferable to select the organophosphorus compound according to the timing of adding the organophosphorus compound.

From the viewpoint of ring-opening polymerization rate and reduction of residual lactide, the organophosphorus compound to be added is selected from the group consisting of R ₁ , R ₂ , and R ₃ if the addition time is a stage having a weight average molecular weight of 10,000 or less. It is preferred that there be no more than one hydrogen. If the organophosphorus compound is added after the completion of the ring-opening polymerization, it is preferable that R ₁ , R ₂ , and R ₃ of the organophosphorus compound have a large proportion of hydrogen from the viewpoint of reducing the residual lactide, and all of them are hydrogen. May be.
The addition amount of the organophosphorus compound is preferably 0.5 to 30-fold mol, particularly preferably 0.5 to 10-fold mol based on the amount of catalyst used for the polymerization. If the amount is less than 0.5 times mol, it may be difficult to obtain the effect of reducing lactide.

  The method for adding the organophosphorus compound is not particularly limited. You may add with the lactide which is a raw material. Moreover, you may add, after raising the temperature of a reaction liquid and melt | dissolving a lactide. Of course, you may add in the middle of a polymerization reaction or after completion | finish of reaction. Among these, it is preferable to add it immediately after dissolving the lactide, that is, before the ring-opening polymerization starts. This is because lactide, an organophosphorus compound, and a catalyst can be quickly mixed, the polymerization efficiency can be increased, and the ultimate molecular weight can be easily controlled.

As the organophosphorus compound represented by the general formula 1 that can be used in the present invention, it is preferable that R ₄ is hydrogen as shown in the general formula 2 in order to increase the reaction efficiency.

(General formula 2)

(Wherein R ₁ , R ₂ and R ₃ represent hydrogen or an alkyl group, and may be the same or different. N represents an integer of 1 or more.)

In this case, the following can be exemplified, but the invention is not limited to these. Compounds in which R ₁ , R ₂ and R ₃ are all alkyl groups include methyl dimethoxyphosphinyl acetate, ethyl diethoxyphosphinyl acetate, ethyl 2- (diethoxyphosphinyl) propanoate, 3- (diethoxy Phosphinyl) ethyl propionate. Examples of the compound in which only _{one of} R ₁ and R ₂ is hydrogen include methyl methoxyphosphinyl acetate, ethyl ethoxyphosphinyl acetate, ethyl 2- (ethoxyphosphinyl) propanoate, 3- (ethoxyphosphini E) Ethyl propionate. Examples of the compound in which both R ₁ and R ₂ are hydrogen among R ₁ , R ₂ and R ₃ include methyl phosphonoacetate, ethyl phosphonoacetate, ethyl 2-phosphonopropanoate and ethyl 3-phosphonopropionate. R _{1, R} 2, of the _{R 3 R 1,} R 2, as all _{R 3} are hydrogen compound phosphonoacetic acid, 2-phosphono propanoic acid, 3-phosphono-propionic. The organic phosphorus compounds listed above may be dissolved in an organic solvent and added to the polymerization reaction system. The solvent to be used may be the same as the ring-opening polymerization initiator or may be of a different type. Specific examples of the solvent include, but are not limited to, methanol, ethanol, propanol, xylene, toluene, ethylene glycol, lauryl alcohol, and the like.

The A-C-A block copolymer and B-C-B block copolymer of the present invention are characterized in that the organophosphorus compound represented by the general formula 1 is copolymerized in a resin. The binding mode is not particularly limited. In this case, the polyhydroxy acid is preferably polylactic acid as described above. However, in consideration of the efficiency of the polymerization process and the like, it is preferable that the polylactic acid segment is bonded to at least one of R ₁ , R ₂ and R ₃ of the organophosphorus compound. Although this bonding mode is not particularly limited, it is preferable that the terminal hydroxyl group of the polylactic acid segment reacts with the carboxyl group or phosphate group site of R ₁ , R ₂ or R ₃ and is bonded by an ester bond.

When the present inventors examined by nuclear magnetic resonance spectrum analysis and ICP emission analysis, the polyester resin of the present invention deactivates the polymerization catalyst by forming a complex between the specific phosphorus compound and the polymerization catalyst, and reduces the residual lactide. It has been suggested. Since the organophosphorus compound is copolymerized in the polyester resin of the present invention, the volatilization of the phosphorous compound due to the heat during ring-opening polymerization and the unreacted monomer performed after completion of the ring-opening polymerization, compared to a simple blend as in the prior art. There is little volatilization of the phosphorus compound in the vacuum distillation step. For this reason, the organic phosphorus compound to be added can efficiently deactivate the polymerization catalyst and suppress the by-product of lactide. That is, in the copolymerized organophosphorus compound represented by the general formula 1, the hydrogenated sites of R ₁ , R ₂ and R ₃ interact with the polymerization catalyst to deactivate the catalytic activity, resulting in polymerization. By-product formation of lactide is suppressed, and further, the production of lactide when the obtained aliphatic polyester resin is subjected to heat processing such as molding is also suppressed. In addition, when most of the copolymerized organophosphorus compounds have a structure in which the R ₃ portion is blocked from the end of the aliphatic polyester as represented by the general formula 4, the aliphatic polyester resin has a back biting reaction. The production of lactide is suppressed, and by-product formation of lactide is also suppressed when the obtained aliphatic polyester resin is subjected to heat treatment such as molding. That is, when the organophosphorus compound represented by the general formula 1 is added before ring-opening polymerization, during ring-opening polymerization or after ring-opening polymerization, any one of R ₁ , R ₂ and R ₃ is a hydroxyl group of the polylactic acid segment. It is believed that they are combined and copolymerized. When any of R ₁ , R ₂ and R ₃ is an alkyl group, at least one of R ₁ , R ₂ and R ₃ not bonded to the polylactic acid segment is subjected to ring-opening polymerization. It is preferable from the viewpoint of suppressing lactide production that the alkyl group is eliminated to form hydrogen.

Among the aliphatic polyester resins of the present invention, preferred structures include those in which a polylactic acid segment is bonded by R ₃ of the general formula 1, and can be represented by the following structure, for example.

（式中、Ｒ_１、Ｒ_２は水素またはアルキル基を表す。ｎは１以上、ｍは３以上の整数である。）
もちろん、Ｒ_１、Ｒ_２、Ｒ_３の全てがポリ乳酸セグメントであるものが含まれても良いが、そのような構造であると、重合触媒を失活するための相互作用部位を有さないため残留ラクチドを低減する効果が小さくなる傾向にある。そのため、Ｒ_１、Ｒ_２、Ｒ_３のうち少なくとも一つがポリ乳酸セグメントであり、それ以外は水素またはアルキル基であることが好ましく、特にＲ_３がポリ乳酸セグメントであり、それ以外は水素またはアルキル基であることがさらに好ましい。ポリ乳酸セグメントでないＲ_１、Ｒ_２、Ｒ_３は水素であることが更に好ましい。

(Wherein R ₁ and R ₂ represent hydrogen or an alkyl group, n is 1 or more, and m is an integer of 3 or more.)
Of course, all of R ₁ , R ₂ and R ₃ may be polylactic acid segments, but such structure does not have an interaction site for deactivating the polymerization catalyst. Therefore, the effect of reducing residual lactide tends to be small. Therefore, it is preferable that at least one of R ₁ , R ₂ , and R ₃ is a polylactic acid segment and the others are hydrogen or an alkyl group, and in particular, R ₃ is a polylactic acid segment, and the others are hydrogen or alkyl. More preferably, it is a group. More preferably, R ₁ , R ₂ and R _{3 which} are not polylactic acid segments are hydrogen.

  The A-C-A block copolymer and B-C-B block copolymer of the present invention are composed of a phosphorus element amount (a1 or a2) in a polylactic acid segment in a resin and a metal element amount (b1 or b) derived from a polymerization catalyst. The molar ratio of b2) is preferably 30 ≧ (a1) / (b1) ≧ 1, or 30 ≧ (a2) / (b2) ≧ 1, more preferably 9 ≧ (a1) / (b1) ≧ 1. 3 or 9 ≧ (a2) / (b2) ≧ 3.

  When (a1) / (b1) (or (a2) / (b2)) is larger than 30, the hue of the resin deteriorates due to the thermally decomposed organophosphorus compound, or the organophosphorus compound is added before ring-opening polymerization. In preparation, the A-C-A block copolymer and the B-C-B block copolymer having the target molecular weight may not be obtained. On the other hand, when (a1) / (b1) (or (a2) / (b2)) is smaller than 1, it is copolymerized in an ACA block copolymer or a BCB block copolymer. The amount of polymerization catalyst deactivated by the phosphorus compound is reduced, and the by-product of lactide during polymerization cannot be sufficiently suppressed. As a result, the A-C-A block copolymer and the B-C-B block co-polymer are produced. The amount of lactide remaining in the coalescence may not be sufficiently reduced. Moreover, there is a possibility that the production of lactide cannot be suppressed when heating such as molding using such a resin.

  In the present invention, the polymerization temperature of the A-C-A block copolymer and the B-C-B block copolymer is preferably lower than the boiling point of the organophosphorus compound to which lactide is dissolved and added. This is because if the polymerization is carried out at a temperature higher than the boiling point of the organophosphorus compound, even if a cooling pipe is provided, the organophosphorus compound is distilled off during the reaction, and the catalyst cannot be deactivated and the residual lactide cannot be reduced. If the polymerization temperature is high, the structural change of the organophosphorus compound is quick and the polymerization catalyst can be deactivated in a short time. However, since the racemization of lactide proceeds, the polymerization temperature is preferably 230 ° C. or lower. That is, the polymerization temperature is particularly preferably in the range of 120 to 200 ° C.

  The aliphatic polyester resin of the present invention can be used in conventionally known fields such as molding materials, films and fibers.

[3] Polylactic acid-based stereocomplex body The polylactic acid-based stereocomplex body of the present invention is a mixture of the above-described ACA block copolymer and BCB block copolymer. Since the A-C-A block copolymer and the B-C-B block copolymer described above have different stereoregularities, a so-called stereo complex is formed by mixing the two. The polylactic acid-based stereocomplex of the present invention, as will be clarified in the experimental examples to be described later, has the above-mentioned melting points in the case of the ACA block copolymer and the BCB block copolymer alone. The melting point (Tm) of 180 to 230 ° C. (preferably 200 to 230 ° C.) is higher, and the thermal stability is improved than the conventional polylactic acid-based polymer. Such a polylactic acid-based stereocomplex of the present invention is expected to be applied as a new polylactic acid-based polymer to engineering applications such as automobiles and home appliances that require a long life and high performance.

  In the polylactic acid-based stereocomplex of the present invention, the number average molecular weight (Mn) of the C segment in the ACA block copolymer or BCB block copolymer is 10,000 or more. The effect of improving brittleness is exhibited, which is particularly preferable.

  The mixing ratio (mass ratio) of the ACA block copolymer and the BCB block copolymer in the polylactic acid-based stereocomplex of the present invention is not particularly limited, but is 1: 0.5 to It is preferably in the range of 2.0, and more preferably in the range of 1: 0.67 to 1.5. When the mixing ratio of the A-C-A block copolymer and the B-C-B block copolymer is less than 1: 0.5, the excess A-C-A block copolymer A This is because a large number of homocrystals based on the segment tend to be generated, and the mixing ratio of the A-C-A block copolymer and the B-C-B block copolymer exceeds 1: 2.0. This is because there is a tendency to produce many homocrystals based on the B segment of the excess B—C—B block copolymer.

  The polylactic acid-based stereocomplex body of the present invention has ordinary additives, that is, an ultraviolet absorber, an antioxidant, a heat stabilizer, a lubricant, a release agent, a dye, and a pigment within a range not impairing the effects of the present invention. Antibacterial and antifungal agents may be blended.

  The polylactic acid-based stereocomplex body of the present invention is prepared by adding an A-C-A block copolymer and a B-C-B block copolymer to a conventionally known appropriate mixing device such as a mill roll, a mixer, a single screw or a twin screw extruder. It can be manufactured by charging and mixing the coalesced material, melting it above its melting point, and then cooling it. The order of charging the A-C-A block copolymer and B-C-B block copolymer into the mixing device is not particularly limited, and either one may be charged first, You may make it throw both into a mixing apparatus simultaneously.

  The temperature of the mixture only needs to be within a temperature range in which the components contained in the mixture melt, and is generally 170 to 230 ° C. The A-C-A block copolymer and the B-C-B block copolymer are uniformly kneaded by melt mixing by heating, and then cooled and crystallized to form a stereocomplex. The molten mixture can be crystallized by cooling, but the stereocomplex structure and crystallinity may differ depending on the cooling conditions.

When mixing the A-C-A block copolymer and the B-C-B block copolymer, a solvent capable of dissolving the A-C-A block copolymer and the B-C-B block copolymer is used. May be used. As the solvent, for example, the A-C-A block copolymer and the B-C-B block copolymer may be dissolved in different solvents, and after mixing them, the solvent may be removed. The solvent is not particularly limited, and any conventionally known appropriate dichloromethane (CH ₂ Cl ₂ ), chloroform (CHCl ₃ ) or the like can be used. From the viewpoint of the evaporation rate of the solvent, it is preferable to use dichloromethane. The A-C-A block copolymer and the B-C-B block copolymer in the solvent may be prepared so as to have a concentration in the range of 10 to 50% by weight from the viewpoint of uniformity. preferable.

  After the solvent is distilled off, the polylactic acid stereocomplex of the present invention is formed by melting under heating under the above conditions and then cooling. In addition, the polylactic acid-type stereocomplex of this invention can be formed suitably also by the solution casting which casts the mixed solution mentioned above under a heating.

  In order to describe the present invention more specifically, examples are described below, but the present invention is not limited thereto. In addition, the characteristic value in an Example was measured with the following method.

(1) Weight average molecular weight It measured by GPC which used chloroform as a mobile phase, connected two TSKgel SuperHZM-N (made by TOSOH) to a column, and used RID-10A (made by SHIMADZU) as a suggestive refractive index detector. The value calculated from the results and converted to polystyrene was used.

(2) Residual lactide content (wt%)
The sample was dissolved in chloroform-d and calculated from the ratio of the integral value of protons derived from polylactic acid and the integral value of protons derived from lactide using a 500 MHz nuclear magnetic resonance spectrum (NMR) apparatus (ARX500 manufactured by Brucker). did.

(3) Determination of copolymerized phosphorus compound (mol%)
40 mg of a sample was dissolved in 0.6 ml of a chloroform-d / DMSO-d = 1/1 (volume ratio) mixed solvent, 5 μl of phosphoric acid was added, and the mixture was allowed to stand at room temperature for 1 hour, and a nuclear magnetic resonance spectrum (NMR) at 500 MHz. Using the apparatus, 1H-NMR was measured.
Based on the result of 1H-NMR, R ₁ and R _{2 in the} general formula 1 change from the structure before addition from the comparison of the integration ratio of the peak derived from the organophosphorus compound and the integration ratio of the peak derived from polylactic acid. The organic phosphorus compound in which the polylactic acid segment is bonded to R ₃ and the organic phosphorus compound in which R ₁ , R ₂ , and R _{3 in} the general formula 1 are not changed from the structure before addition are divided into The amount was calculated.
Furthermore, 500 mg of the synthesized polylactic acid resin was dissolved in 2.5 ml of a chloroform-d / DMSO-d = 1/1 mixed solvent (volume ratio), about 80 mg of phosphoric acid was added, and the mixture was allowed to stand at room temperature for 1 hour. 31P-NMR was measured using a nuclear magnetic resonance spectrum (NMR) apparatus. From the result of 31P-NMR, it was found that the organic phosphorus compound, in which no peak was seen by 1H-NMR, was present.
From the amount of the organic phosphorus compound calculated from the 1H-NMR measurement and the result of the 31P-NMR measurement, the amount of the organic phosphorus compound copolymerized with the polylactic acid among the organic phosphorus compounds contained in the polylactic acid was calculated. .
The calculated amount (mol%) of the organophosphorus compound copolymerized represents the amount of lactide constituting polylactic acid.

(4) Determination of amount of phosphorus and polymerization catalyst metal 3 mL of nitric acid was added to 0.2 g of the polymer after polymerization, and a measurement solution was prepared by a hermetic high-pressure wet decomposition method. The measurement liquid was quantified by the ICP luminescence method.

(5) Measurement of crystalline melting point 3.5 mg of a sample was sealed in a pan and heated at a rate of 10 ° C./min using DSC-50 (manufactured by Shimadzu) and measured.

(6) Storage stability A sample was allowed to stand under conditions of a temperature of 40 ° C. and a humidity of 85%, and the weight average molecular weight (Mw) and dispersity (PDI) before and after the measurement were measured and compared.

<Polymer synthesis scheme>
A polyhexamethylene carbonate diol (PHMC) having a number average molecular weight (Mn) of 2000 Da (measured by 500 MHz ¹ H NMR (measured by ARX500 (manufactured by Brucker)) and diphenyl carbonate are reacted, and the number average molecular weight (Mn) is 10,000 Da or PHMC of 15000 Da (measured by 500 MHz ¹ H NMR (measured by ARX500 (manufactured by Brucker))) was synthesized.

  Next, according to the following reaction scheme, L-lactide or D-lactide is copolymerized with PHMC having a number average molecular weight (Mn) of 10000 Da or 15000 Da to obtain an ACA (PLLA-PHMC-PLLA) block copolymer. Alternatively, a B-C-B block (PDLA-PHMC-PDLA) copolymer was synthesized. In the following reaction scheme, enantiomerism is not indicated.

<Experimental example 1>
After adding 1.5 g of PHMC having a number average molecular weight (Mn) of 15000 Da, 2.5 g of L-lactide or D-lactide and drying under reduced pressure, tin octylate (Sn (N Oct) ₂ ) in toluene, 7.0 μl, and 23.3 μl of diethoxyphosphinylethyl acetate in toluene prepared to a concentration of 0.1 g / ml were added. Thereafter, the reaction was carried out at 180 ° C. for 1.5 hours, and the pressure was reduced at 0.1 Torr for 0.5 hours to synthesize the following samples.
Sample 1L: PLLA-PHMC-PLLA
Sample 1D: PDLA-PHMC-PDLA

<Experimental example 2>
After adding 1.0 g of PHMC having a number average molecular weight (Mn) of 10,000 Da, 3.0 g of L-lactide or D-lactide, and drying under reduced pressure, tin octylate (Sn (N Oct) ₂ ) in toluene solution 8.4 μl and diethoxyphosphinylethyl acetate in toluene solution 28.0 μl prepared to a concentration of 0.1 g / ml were added. Thereafter, the reaction was carried out at 180 ° C. for 1.5 hours, and the pressure was reduced at 0.1 Torr for 0.5 hours to synthesize the following samples.
Sample 2L: PLLA-PHMC-PLLA
Sample 2D: PDLA-PHMC-PDLA

<Experimental example 3>
A sample was synthesized in the same manner as in Experimental Example 1 except that the amount of the toluene solution of ethyl diethoxyphosphinyl acetate was changed to 116.5 μl.
・ Sample 3L: PLLA-PHMC-PLLA
Sample 3D: PDLA-PHMC-PDLA

<Experimental example 4>
A sample was synthesized in the same manner as in Experimental Example 2 except that the amount of ethyl diethoxyphosphinyl acetate in toluene was 140 μl.
Sample 4L: PLLA-PHMC-PLLA
Sample 4D: PDLA-PHMC-PDLA

<Experimental example 5>
After adding 1.5 g of PHMC having a number average molecular weight (Mn) of 15000 Da, 2.5 g of L-lactide or D-lactide and drying under reduced pressure, tin octylate (Sn (N 7.0 μl of a toluene solution of Oct) ₂ ) was added. Thereafter, the reaction was carried out at 180 ° C. for 1.5 hours, and the pressure was reduced at 0.1 Torr for 0.5 hours to synthesize the following samples.
・ Sample 5L: PLLA-PHMC-PLLA
Sample 5D: PDLA-PHMC-PDLA

<Experimental example 6>
After adding 1.0 g of PHMC having a number average molecular weight (Mn) of 10,000 Da, 3.0 g of L-lactide or D-lactide, and drying under reduced pressure, tin octylate (Sn (N 8.4 μl of a toluene solution of Oct) ₂ ) was added. Thereafter, the reaction was carried out at 180 ° C. for 1.5 hours, and the pressure was reduced at 0.1 Torr for 0.5 hours to synthesize the following samples.
・ Sample 6L: PLLA-PHMC-PLLA
Sample 6D: PDLA-PHMC-PDLA

<Experimental example 7>
After adding 1.5 g of PHMC having a number average molecular weight (Mn) of 15000 Da, 2.5 g of L-lactide or D-lactide and drying under reduced pressure, tin octylate (Sn (N Oct) ₂ ) in toluene (7.0 μl) and trimethyl phosphate in toluene (73.0 μl) prepared to a concentration of 0.1 g / ml were added. Thereafter, the reaction was carried out at 180 ° C. for 1.5 hours, and the pressure was reduced at 0.1 Torr for 0.5 hours to synthesize the following samples.
Sample 7L: PLLA-PHMC-PLLA
Sample 7D: PDLA-PHMC-PDLA

<Experimental Example 8>
After adding 1.0 g of PHMC having a number average molecular weight (Mn) of 10,000 Da, 3.0 g of L-lactide or D-lactide, and drying under reduced pressure, tin octylate (Sn (N Oct) ₂ ) in toluene (8.4 μl) and trimethyl phosphate in toluene (87.5 μl) prepared to a concentration of 0.1 g / ml were added. Thereafter, the reaction was carried out at 180 ° C. for 1.5 hours, and the pressure was reduced at 0.1 Torr for 0.5 hours to synthesize the following samples.
・ Sample 8L: PLLA-PHMC-PLLA
Sample 8D: PDLA-PHMC-PDLA

  Table 1 shows the results of measurement of tin, phosphorus element amount, copolymerized phosphorus compound amount, residual lactide amount, and melting point of each sample.

<Examples 1-4, Comparative Examples 1-4>
Each sample synthesized as described above was dissolved in dichloromethane to a concentration of 10% by weight at room temperature.
For example, in the case of Example 1, using a magnetic stirrer, sample 1L and sample 1D were mixed at room temperature for 1 hour, and the polylactic acid-based stereo of the present invention was cast using the cast method (condition: let the petri dish stand overnight on a horizontal surface) A complex film-like product (Sample 1L-1D) was produced.
Similarly, other samples were also mixed to prepare polylactic acid-based stereocomplex film-like materials. In all cases, the film formability was good.

  Table 2 shows the melting point, weight average molecular weight (Mw) (Da) and dispersity (PDI) before and after the storage stability test for each sample. It can be seen that the polylactic acid-based stereocomplex of the present invention has improved heat resistance due to an increase in melting point. Further, it can be seen that also in the storage stability test, the hydrolysis of the polymer is suppressed and the storage stability is improved.

  The embodiments and experimental examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The polylactic acid-based stereocomplex body of the present invention is expected to be applied as a new polylactic acid-based polymer to engineering applications such as automobiles and home appliances that require a long life and high performance.

Claims (7)

A block copolymer having a segment mainly composed of an L-lactic acid unit and having an organic phosphorus compound represented by the general formula 1 copolymerized at both ends of a segment mainly containing an aliphatic carbonate unit; and an aliphatic carbonate unit. A polylactic acid characterized in that it is a mixture with a block copolymer having a segment mainly composed of D-lactic acid units at both ends of a segment containing the organic phosphorus compound represented by the general formula 1 System stereo complex body.
(General formula 1)

(Wherein R ₁ , R ₂ , R ₃ and R ₄ represent hydrogen or an alkyl group, and may be the same or different. N represents an integer of 1 or more.)   A block copolymer having a segment mainly composed of an L-lactic acid unit and having an organic phosphorus compound represented by the general formula 1 copolymerized at both ends of a segment mainly containing an aliphatic carbonate unit; and an aliphatic carbonate unit. The mixing ratio of the block copolymer having a segment mainly composed of D-lactic acid units and having an organic phosphorus compound represented by the general formula 1 copolymerized at both ends of the segment is 1: 0.5-2. The polylactic acid-based stereocomplex according to claim 1, which is within a range of 0.0. In the segment mainly composed of L-lactic acid units and copolymerized with the organophosphorus compound represented by the general formula 1, the organophosphorus compound is bonded to at least one of R ₁ , R ₂ and R _3. The organic phosphorus compound is bonded to at least one of R ₁ , R _2, and R _{3 in} the segment mainly composed of D-lactic acid unit and copolymerized with the organic phosphorus compound represented by the general formula 1. The polylactic acid-based stereocomplex according to claim 1 or 2, wherein In the segment composed mainly of L-lactic acid unit and copolymerized with the organic phosphorus compound represented by the general formula 1, the organic phosphorus compound is bonded with R ₃ and consists mainly of the D-lactic acid unit. 4. The polylactic acid-based stereocomplex according to claim 3, wherein in the segment in which the organophosphorus compound represented by Formula 1 is copolymerized, the organophosphorus compound is bonded by R _{3. 5} . The molar ratio of the phosphorus element (a1) and the metal element (b1) derived from the polymerization catalyst in the segment mainly composed of L-lactic acid units and copolymerized with the organophosphorus compound represented by the general formula 1 is as follows. The relationship between the phosphorus element (a2) and the metal element (b2) derived from the polymerization catalyst in the segment mainly composed of D-lactic acid units and copolymerized with the organophosphorus compound represented by the general formula 1 is satisfied. The polylactic acid-based stereocomplex according to claim 4, wherein the molar ratio satisfies the following relationship.
30 ≧ (a1) / (b1) ≧ 1
30 ≧ (a2) / (b2) ≧ 1   The polylactic acid-based stereocomplex according to any one of claims 1 to 5, wherein the aliphatic carbonate unit is a polycarbonate diol comprising a 1,6-hexanediol residue.   The polylactic acid-type stereocomplex body in any one of Claims 1-6 whose number average molecular weight of the segment which mainly contains an aliphatic aliphatic carbonate unit is 2000 or more.