JP2008201680A - Method for producing lactide from polylactic acid - Google Patents
Method for producing lactide from polylactic acid Download PDFInfo
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- JP2008201680A JP2008201680A JP2007036035A JP2007036035A JP2008201680A JP 2008201680 A JP2008201680 A JP 2008201680A JP 2007036035 A JP2007036035 A JP 2007036035A JP 2007036035 A JP2007036035 A JP 2007036035A JP 2008201680 A JP2008201680 A JP 2008201680A
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- lactide
- polylactic acid
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- lactic acid
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- JJTUDXZGHPGLLC-UHFFFAOYSA-N lactide Chemical compound CC1OC(=O)C(C)OC1=O JJTUDXZGHPGLLC-UHFFFAOYSA-N 0.000 title claims abstract description 69
- 229920000747 poly(lactic acid) Polymers 0.000 title claims abstract description 62
- 239000004626 polylactic acid Substances 0.000 title claims abstract description 59
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 claims abstract description 26
- 150000001875 compounds Chemical class 0.000 claims abstract description 14
- 235000014655 lactic acid Nutrition 0.000 claims abstract description 13
- 239000004310 lactic acid Substances 0.000 claims abstract description 13
- 239000003054 catalyst Substances 0.000 claims abstract description 12
- 239000000203 mixture Substances 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- 150000003606 tin compounds Chemical group 0.000 claims description 3
- 239000000539 dimer Substances 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 18
- 230000000593 degrading effect Effects 0.000 abstract 2
- 230000015556 catabolic process Effects 0.000 abstract 1
- 238000006731 degradation reaction Methods 0.000 abstract 1
- JJTUDXZGHPGLLC-IMJSIDKUSA-N 4511-42-6 Chemical compound C[C@@H]1OC(=O)[C@H](C)OC1=O JJTUDXZGHPGLLC-IMJSIDKUSA-N 0.000 description 16
- 230000003287 optical effect Effects 0.000 description 13
- 238000005979 thermal decomposition reaction Methods 0.000 description 13
- 238000000197 pyrolysis Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000006116 polymerization reaction Methods 0.000 description 6
- 229930182843 D-Lactic acid Natural products 0.000 description 4
- JVTAAEKCZFNVCJ-UWTATZPHSA-N D-lactic acid Chemical compound C[C@@H](O)C(O)=O JVTAAEKCZFNVCJ-UWTATZPHSA-N 0.000 description 4
- JVTAAEKCZFNVCJ-REOHCLBHSA-N L-lactic acid Chemical compound C[C@H](O)C(O)=O JVTAAEKCZFNVCJ-REOHCLBHSA-N 0.000 description 4
- 229940022769 d- lactic acid Drugs 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 2
- 229920001432 poly(L-lactide) Polymers 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 2
- 229910001887 tin oxide Inorganic materials 0.000 description 2
- TXUICONDJPYNPY-UHFFFAOYSA-N (1,10,13-trimethyl-3-oxo-4,5,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-17-yl) heptanoate Chemical compound C1CC2CC(=O)C=C(C)C2(C)C2C1C1CCC(OC(=O)CCCCCC)C1(C)CC2 TXUICONDJPYNPY-UHFFFAOYSA-N 0.000 description 1
- 239000002028 Biomass Substances 0.000 description 1
- -1 DD-lactide Chemical compound 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 229910021626 Tin(II) chloride Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229920000704 biodegradable plastic Polymers 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003480 eluent Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- WWZKQHOCKIZLMA-UHFFFAOYSA-N octanoic acid Chemical compound CCCCCCCC(O)=O WWZKQHOCKIZLMA-UHFFFAOYSA-N 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 230000006340 racemization Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- UQDJGEHQDNVPGU-UHFFFAOYSA-N serine phosphoethanolamine Chemical compound [NH3+]CCOP([O-])(=O)OCC([NH3+])C([O-])=O UQDJGEHQDNVPGU-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 235000011150 stannous chloride Nutrition 0.000 description 1
- 239000001119 stannous chloride Substances 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J11/00—Recovery or working-up of waste materials
- C08J11/04—Recovery or working-up of waste materials of polymers
- C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
- C08J11/16—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with inorganic material
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J11/00—Recovery or working-up of waste materials
- C08J11/04—Recovery or working-up of waste materials of polymers
- C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
- C08J11/18—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material
- C08J11/22—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material by treatment with organic oxygen-containing compounds
- C08J11/26—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material by treatment with organic oxygen-containing compounds containing carboxylic acid groups, their anhydrides or esters
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2367/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Heterocyclic Compounds That Contain Two Or More Ring Oxygen Atoms (AREA)
- Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
Description
本発明は、ポリ乳酸を、乳酸オリゴマー化合物と触媒共存下熱分解反応させ、熱分解生成物としてラクチドを製造する、ポリ乳酸からラクチドを製造する方法に関する。 The present invention relates to a method for producing lactide from polylactic acid, in which polylactic acid is thermally decomposed with a lactic acid oligomer compound in the presence of a catalyst to produce lactide as a thermal decomposition product.
ポリ乳酸は、従来から、環境への負荷が少ない生分解性プラスチックの代表としてよく知られてきた。近年、循環型社会構築気運が高まり、プラスチック原料が化石資源からバイオマスへ転換する動きがあり、デンプンなど植物が原料となるポリ乳酸が大きな注目を集めている。このポリ乳酸は、その物性として透明性に優れ、成形加工の多様性があり、安全性も高いため、農林水産用資材、土木・建築資材、食品包装・容器、又は日用品用途などでの各方面での使用が期待されている。 Conventionally, polylactic acid has been well known as a representative of biodegradable plastics that have a low environmental impact. In recent years, the trend of building a recycling-oriented society has increased, and plastic raw materials have been moved from fossil resources to biomass, and polylactic acid from plants such as starch has attracted much attention. This polylactic acid has excellent transparency, has a wide variety of molding processes, and is highly safe, so it can be used in various fields such as agricultural, forestry and fishery materials, civil engineering / building materials, food packaging / containers, or daily necessities. Use in is expected.
しかしながら、上記のような使用の増大に伴って大量に発生する、使用済みポリ乳酸、及びポリ乳酸製造段階で発生する品質不適格品（以下、これらを含めてポリ乳酸と略称することがある。）については、ポリ乳酸部位は生分解性を有するものの分解までに長時間を要し、またポリ乳酸以外の部位は生分解性を有さないことが多くそのまま自然界に残り、今後大きな社会問題となることが予想される。上記の問題に対して、ポリ乳酸を元の原料に変換・回収し、この原料から再度重合反応等によってポリ乳酸ポリマーを製造し再利用する、いわゆるケミカルリサイクルが有効である。この方法は、基本的にロスの無い、化合物の資源再使用が可能な方法であり、資源の再利用が可能となる。 However, used polylactic acid generated in large quantities with the increase in use as described above, and non-qualified products generated in the polylactic acid production stage (hereinafter, these may be abbreviated as polylactic acid in some cases). ), Although the polylactic acid part is biodegradable, it takes a long time to decompose, and the parts other than polylactic acid often do not have biodegradability and remain in the natural world. It is expected to be. In order to solve the above problems, so-called chemical recycling in which polylactic acid is converted and recovered to the original raw material, and the polylactic acid polymer is produced from the raw material by a polymerization reaction again and reused is effective. This method is basically a loss-free method that enables resource reuse of compounds, and enables resource reuse.
例えば、ポリ乳酸を熱分解してラクチドを回収する方法として、ポリ乳酸製品をスクリュー式押出機内において水及び触媒の存在下、２００〜４００℃に加熱してラクチドを回収する方法が提案されている（例えば特許文献１参照。）。 For example, as a method for recovering lactide by thermally decomposing polylactic acid, a method for recovering lactide by heating a polylactic acid product to 200 to 400 ° C. in the presence of water and a catalyst in a screw extruder has been proposed. (For example, refer to Patent Document 1).
また、高分子量のポリ乳酸（重量平均分子量：５０００〜３０万）をスズ又はスズ化合物からなる触媒の存在下、ポリ乳酸の溶融温度以上の温度（１７０℃〜３００℃）に加熱すると共に、前記温度におけるラクチドの蒸気圧以下の圧力に減圧して、生成したラクチドを留去して回収する方法が提案されている（例えば特許文献２参照。）。 Moreover, while heating high molecular weight polylactic acid (weight average molecular weight: 5000 to 300,000) in the presence of a catalyst made of tin or a tin compound to a temperature higher than the melting temperature of polylactic acid (170 ° C to 300 ° C), A method has been proposed in which the pressure is reduced to a pressure equal to or lower than the vapor pressure of lactide at a temperature, and the produced lactide is distilled off and recovered (see, for example, Patent Document 2).
しかしながら、いずれの方法もポリ乳酸と触媒をそのまま混合し熱分解しているため、直接熱処理中にポリ乳酸の光学純度が低下するのが避けられない。この光学純度の低下は最終的には、ポリ乳酸の品質低下を招くという問題がある。 However, in either method, polylactic acid and the catalyst are mixed as they are and thermally decomposed, so that the optical purity of polylactic acid is inevitably lowered during direct heat treatment. This decrease in optical purity ultimately has the problem of causing a decrease in the quality of polylactic acid.
本発明の目的は、従来技術が有していた問題点を解決し、ポリ乳酸を熱分解してラクチドを製造する際、ポリ乳酸の熱分解温度を下げ、光学純度の良好な良好なラクチドを製造する方法を提供することにある。 The object of the present invention is to solve the problems of the prior art, and when producing lactide by thermally decomposing polylactic acid, the thermal decomposition temperature of polylactic acid is lowered, and good lactide with good optical purity is obtained. It is to provide a method of manufacturing.
本発明者らは上記従来技術に鑑み、鋭意検討を行った結果、本発明を完成するに至った。すなわち、本発明は、ポリ乳酸を熱分解してラクチドを製造する方法であって、ポリ乳酸、乳酸オリゴマー化合物及び触媒の共存下、且つ１７０℃〜２４５℃の温度下、前記温度におけるラクチドの蒸気圧以下の圧力条件下にて、生成したラクチドを留去させながらポリ乳酸からラクチドを製造する方法である。 As a result of intensive studies in view of the above-described prior art, the present inventors have completed the present invention. That is, the present invention is a method for producing lactide by thermally decomposing polylactic acid, wherein the vapor of lactide in the presence of polylactic acid, a lactic acid oligomer compound and a catalyst, and at a temperature of 170 ° C. to 245 ° C. This is a method for producing lactide from polylactic acid while distilling off the produced lactide under a pressure condition equal to or lower than the pressure.
本発明の方法によれば、ポリ乳酸を熱分解してラクチドを製造する場合、ポリ乳酸の熱分解温度を下げ、品質の良好な、その具体例の１つとしては光学純度の良好なラクチドを製造することが可能である。また、同一条件下での熱分解時、より多くのラクチドを回収することも可能となる。 According to the method of the present invention, when lactide is produced by thermally decomposing polylactic acid, the thermal decomposition temperature of polylactic acid is lowered, and as one of its specific examples, lactide with good optical purity is used. It is possible to manufacture. It is also possible to recover more lactide during pyrolysis under the same conditions.
本発明において、ポリ乳酸とは主成分がポリ乳酸であり、ポリ乳酸を全体の６０重量％以上含むものが好ましく、より好ましくは８０重量％以上である。ポリ乳酸については、ポリＬ−乳酸、ポリＤ−乳酸、ラセミ状のポリ乳酸、ポリＬ−乳酸とポリＤ−乳酸の混合物、ポリ乳酸ステレオコンプレックスポリマーなど各種ポリ乳酸に適用できる。また、本発明の方法には、各種ポリ乳酸と他の異素材との混合物にも適用可能である。さらに本発明の方法においては、ポリ乳酸は一般に水洗浄及び粗粉砕などの前処理を施し、熱分解反応に適した形状にしてから投入することが好ましい。この際に水に極めて易溶な異素材も取り除くことができるので好ましい。またこの前処理を行う前及び／又は行った後で、簡易的な機械的又は物理的手段によって可能な限りポリ乳酸から異素材を取り除くことが好ましい。例えば目視で異素材と判別できるものを取り除く方法、又は磁石を用いて磁石に吸い付けられる金属類を取り除くなどの方法である。 In the present invention, polylactic acid is mainly composed of polylactic acid, and preferably contains 60% by weight or more of polylactic acid, more preferably 80% by weight or more. The polylactic acid can be applied to various polylactic acids such as poly L-lactic acid, poly D-lactic acid, racemic polylactic acid, a mixture of poly L-lactic acid and poly D-lactic acid, and a polylactic acid stereocomplex polymer. The method of the present invention can also be applied to a mixture of various polylactic acids and other different materials. Furthermore, in the method of the present invention, it is preferable to add polylactic acid after pretreatment such as washing with water and coarse pulverization to obtain a shape suitable for the thermal decomposition reaction. In this case, it is preferable because foreign materials that are extremely soluble in water can be removed. Further, before and / or after this pretreatment, it is preferable to remove foreign materials from polylactic acid as much as possible by simple mechanical or physical means. For example, there are a method of removing a material that can be visually discriminated from a different material, or a method of removing a metal attracted to the magnet using a magnet.
更にラクチドとは、構成する乳酸の種類により、３種類存在する。Ｌ−乳酸２分子から成るラクチドは、ＬＬ−ラクチドとなり、同様にＤ−乳酸２分子から成るラクチドは、ＤＤ−ラクチド、Ｌ−乳酸とＤ−乳酸１分子づつから成るものはＤＬ−ラクチドとなる。 Furthermore, there are three types of lactide depending on the type of lactic acid to be constituted. A lactide composed of two L-lactic acid molecules becomes LL-lactide, and similarly, a lactide composed of two D-lactic acid molecules becomes DD-lactide, and one composed of one molecule of L-lactic acid and one D-lactic acid becomes DL-lactide. .
本発明の実施方法は、前記ポリ乳酸を乳酸オリゴマー化合物と触媒共存下、１７０℃〜２４５℃の温度下、前記温度におけるラクチドの蒸気圧以下の圧力条件にして、生成したラクチドを留去させながら製造する。 In the method of the present invention, the polylactic acid is distilled in the presence of a lactic acid oligomer compound and a catalyst at a temperature of 170 ° C. to 245 ° C. under a pressure condition equal to or lower than the vapor pressure of lactide at the above temperature. To manufacture.
ポリ乳酸の熱分解方法については、ポリ乳酸の性状に特に限定されることはなく、そのポリ乳酸の性状等によって、任意に温度、時間、乳酸オリゴマー化合物の量及び触媒の量等を調整することができる。また、熱分解反応は回分式又は連続式いずれも採用可能である。 The thermal decomposition method of polylactic acid is not particularly limited to the properties of polylactic acid, and the temperature, time, amount of lactic acid oligomer compound, amount of catalyst, etc. can be arbitrarily adjusted depending on the properties of polylactic acid. Can do. In addition, the batch or continuous thermal decomposition reaction can be employed.
熱分解反応において、温度は、１７０℃〜２４５℃であることが必要である。熱分解温度が２４５℃より高くなると、ラクチドのラセミ化の進行が極端に早くなる。一方、熱分解温度が１７０℃より低いと、熱分解反応が進まなくなる。 In the pyrolysis reaction, the temperature needs to be 170 ° C to 245 ° C. When the thermal decomposition temperature is higher than 245 ° C., the progress of racemization of lactide becomes extremely fast. On the other hand, when the thermal decomposition temperature is lower than 170 ° C., the thermal decomposition reaction does not proceed.
熱分解圧力については、前記熱分解温度におけるラクチドの蒸気圧以下の圧力条件に設定される。圧力は低いほど留出温度が低下する分好ましいが、圧力を低くし過ぎると留去したラクチドが固化するため、熱分解圧力は、ラクチドの固化温度以上、熱分解温度におけるラクチドの蒸気圧以下にすることが好ましい。 About a pyrolysis pressure, it sets to the pressure conditions below the vapor pressure of the lactide in the said pyrolysis temperature. The lower the pressure, the lower the distillation temperature, which is preferable. However, if the pressure is too low, the distilled lactide solidifies, so the pyrolysis pressure is higher than the lactide solidification temperature and lower than the lactide vapor pressure at the pyrolysis temperature. It is preferable to do.
反応時間については、反応温度、反応圧力、ポリ乳酸の性状、使用する水の量により任意に設定することが可能であるが、ラクチドの光学純度維持のため、より短時間で実施することが好ましい。 The reaction time can be arbitrarily set depending on the reaction temperature, reaction pressure, properties of polylactic acid, and the amount of water used, but it is preferable to carry out the reaction in a shorter time in order to maintain the optical purity of lactide. .
本発明の製造方法において使用する乳酸オリゴマー化合物については、重合度が２以上１００以下の多量体化合物の単体及び／或いは重合度が２以上１００以下の多量体化合物の混合物を使用することができる。また、使用する量については、ポリ乳酸に対し０．５〜５ｗｔ％であることが好ましい。使用量が少なくなると、ポリ乳酸の熱分解温度低下の効果が薄れる。単体とは重合度が単分散の化合物を指している。一方、重合度が１００を超える場合がポリ乳酸を意味する。 As the lactic acid oligomer compound used in the production method of the present invention, a single polymer compound having a polymerization degree of 2 to 100 and / or a mixture of multimer compounds having a polymerization degree of 2 to 100 can be used. The amount used is preferably 0.5 to 5 wt% with respect to polylactic acid. When the amount used is reduced, the effect of lowering the thermal decomposition temperature of polylactic acid is diminished. A simple substance refers to a compound having a monodispersed degree of polymerization. On the other hand, the case where the degree of polymerization exceeds 100 means polylactic acid.
また、本発明の製造方法において使用する触媒については、ポリ乳酸の熱分解で用いられる既知の触媒を用いるが、その中でも特に、酸化スズ、オクチル酸スズ、塩化第一スズ等スズ化合物であることが好ましい。 In addition, as the catalyst used in the production method of the present invention, a known catalyst used in the thermal decomposition of polylactic acid is used, and among these, tin compounds such as tin oxide, tin octylate and stannous chloride are particularly used. Is preferred.
更に、本発明の製造方法において使用する反応装置については、連続式或いは回分式いずれも適用可能であり、スクリュー式押出機タイプ或いは反応釜タイプいずれも適用可能である。 Furthermore, as the reaction apparatus used in the production method of the present invention, either a continuous type or a batch type is applicable, and a screw type extruder or a reaction kettle type is applicable.
以下、実施例により本発明の内容を更に具体的に説明するが、本発明はこれにより何ら
限定を受けるものではない。尚実施例及び比較例において「部」と称しているものは重
量部を表す。
Hereinafter, the content of the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In addition, what is called "part" in an Example and a comparative example represents a weight part.
（１）各ラクチド異性体の収量の測定方法（ｍｏｌ％）
ポリ乳酸を熱分解して得られるラクチドは、高速液体クロマトグラフ（カラム：ダイセル化学 ＣＨＩＲＡＬＳＥＬ ＯＤ−Ｈ（φ０．４６×Ｌ２５ｃｍ.）、溶離液：ｎ−ヘキサン／２−プロパノール＝９０／１０）によって測定し、ＬＬ−ラクチド、ＤＤ−ラクチド、ＤＬ−ラクチドの割合を求めた。
(1) Method for measuring yield of each lactide isomer (mol%)
The lactide obtained by thermally decomposing polylactic acid is obtained by a high performance liquid chromatograph (column: Daicel Chemical CHIRALSEL OD-H (φ0.46 × L25 cm.), Eluent: n-hexane / 2-propanol = 90/10). The ratio of LL-lactide, DD-lactide and DL-lactide was determined.
（２）ラクチドの回収率の求め方（ｍｏｌ％）
ラクチドの回収率については、まずポリ乳酸を熱分解して得られるラクチドの重量を把握し、ラクチドの分子量及びポリ乳酸の単位分子量を用い、次の式にて求めた。
ラクチドの回収率＝（ラクチドの重量部／１４４×２）／（ポリ乳酸の重量部／９０）×１００
ここで１４４、９０はそれぞれラクチドと乳酸の分子量を表す。
(2) Determination of lactide recovery rate (mol%)
The lactide recovery rate was determined by the following formula using the molecular weight of lactide and the unit molecular weight of polylactic acid by first grasping the weight of lactide obtained by thermal decomposition of polylactic acid.
Lactide recovery rate = (parts by weight of lactide / 144 × 2) / (parts by weight of polylactic acid / 90) × 100
Here, 144 and 90 represent the molecular weights of lactide and lactic acid, respectively.
（３）ＬＬ−ラクチドの光学純度の測定方法（％ｅｅ）
ＬＬ−ラクチドの光学純度については、得られたＬＬ−ラクチド、ＤＤ−ラクチド及びＤＬ−ラクチドの量を用い、次の式にて求めた。
ＬＬ−ラクチドの光学純度＝{（ＬＬ−ラクチドの重量部）−（ＤＤ−ラクチドの重量部）−（ＤＬ−ラクチドの重量部）}／{（ＬＬ−ラクチドの重量部）＋（ＤＤ−ラクチドの重量部）＋（ＤＬ−ラクチドの重量部）}×１００
(3) Measuring method of optical purity of LL-lactide (% ee)
About the optical purity of LL-lactide, it calculated | required with the following formula | equation using the quantity of the obtained LL-lactide, DD-lactide, and DL-lactide.
Optical purity of LL-lactide = {(part by weight of LL-lactide) − (part by weight of DD-lactide) − (part by weight of DL-lactide)} / {(part by weight of LL-lactide) + (DD-lactide Parts by weight) + (parts by weight of DL-lactide)} × 100
〔実施例１〕
ポリ乳酸（Ｌ体＝９７．７％ｅｅ、融点１６０〜１７０℃、フクビ化学製ポリ乳酸壁面パネル）１００部、酸化スズ０．５部、乳酸オリゴマー（酸価：７１ＫＯＨｍｇ／ｇ、平均重合度：約１０）３．０部を熱分解槽に投入し、３００ｒｐｍで攪拌下徐々に加温し温度を上げ、ポリ乳酸が溶融した段階で、２０ｍｍＨｇまで減圧した。更にラクチドが留出する２１１〜２１５℃の温度条件とし、ベーパー状でラクチドを留出させ空冷により固体状のラクチドを回収した。ラクチドが留出開始してから１．５時間で得られたラクチド生成物を分析したところ、ラクチドの収率は８７．５％ｍｏｌ％であり、ＬＬ−ラクチドの収率は７６．０ｍｏｌ％であった。この結果からＬＬ−ラクチドの光学純度は、７３．７％ｅｅであった。
[Example 1]
100 parts of polylactic acid (L-form = 97.7% ee, melting point 160-170 ° C., polylactic acid wall panel manufactured by Fukubi Chemical Co., Ltd.), 0.5 part of tin oxide, lactic acid oligomer (acid value: 71 KOHmg / g, average degree of polymerization: About 10) 3.0 parts were put into a pyrolysis tank, heated gradually with stirring at 300 rpm, the temperature was raised, and the pressure was reduced to 20 mmHg when polylactic acid was melted. Furthermore, it was set as the temperature conditions of 211-215 degreeC in which a lactide distills, lactide was distilled in vapor form, and solid lactide was collect | recovered by air cooling. When the lactide product obtained 1.5 hours after the start of the distillation of lactide was analyzed, the yield of lactide was 87.5% mol%, and the yield of LL-lactide was 76.0 mol%. there were. From this result, the optical purity of LL-lactide was 73.7% ee.
〔実施例２〕
実施例１において、乳酸オリゴマーの量を１．０部に変更し、同様の操作を行った。ラクチドの留出した温度は２１５〜２２０℃の条件であった。その結果、得られたラクチド生成物を分析したところ、ラクチドの収率は８４．０％ｍｏｌ％であり、ＬＬ−ラクチドの収率は７７．４ｍｏｌ％であった。この結果からＬＬ−ラクチドの光学純度は、８４．３％ｅｅであった。
[Example 2]
In Example 1, the amount of lactic acid oligomer was changed to 1.0 part, and the same operation was performed. The temperature at which lactide was distilled was 215 to 220 ° C. As a result, when the obtained lactide product was analyzed, the yield of lactide was 84.0% mol% and the yield of LL-lactide was 77.4 mol%. From this result, the optical purity of LL-lactide was 84.3% ee.
〔比較例１〕
実施例１において、圧力を１００ｍｍＨｇとし、更にラクチドが留出する２４７〜２５２℃の温度条件とし、同様の操作を行った。その結果、得られたラクチド生成物を分析したところ、ラクチドの収率は７０．５％ｍｏｌ％であり、ＬＬ−ラクチドの収率は４４．４ｍｏｌ％であった。この結果からＬＬ−ラクチドの光学純度は、２６．０％ｅｅであった。
[Comparative Example 1]
In Example 1, the pressure was set to 100 mmHg, and the temperature was set to 247 to 252 ° C. at which lactide was distilled off, and the same operation was performed. As a result, when the obtained lactide product was analyzed, the yield of lactide was 70.5% mol% and the yield of LL-lactide was 44.4 mol%. From this result, the optical purity of LL-lactide was 26.0% ee.
〔比較例２〕
実施例１において、乳酸オリゴマーを加えずに、同様の操作を行った。その結果、ラクチドの留出した温度は２８０〜２９０℃の条件であった。その結果、得られたラクチド生成物を分析したところ、ラクチドの収率は４０．９％ｍｏｌ％であり、ＬＬ−ラクチドの収率は３０．７ｍｏｌ％であった。この結果からＬＬ−ラクチドの光学純度は、５０．１％ｅｅであった。
[Comparative Example 2]
In Example 1, the same operation was performed without adding the lactic acid oligomer. As a result, the temperature at which lactide was distilled was 280 to 290 ° C. As a result, when the obtained lactide product was analyzed, the yield of lactide was 40.9% mol% and the yield of LL-lactide was 30.7 mol%. From this result, the optical purity of LL-lactide was 50.1% ee.
本発明により、ポリ乳酸を熱分解してラクチドを製造する際、ポリ乳酸の熱分解温度を下げ、光学純度の高いラクチドを得られる等、品質の良好なラクチドを高収率で製造することができ、その工業的な意義は大きい。 According to the present invention, when producing lactide by thermally decomposing polylactic acid, it is possible to produce lactide with good quality in high yield, such as lowering the thermal decomposition temperature of polylactic acid and obtaining lactide with high optical purity. Yes, its industrial significance is great.
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| JP2011162480A (en) * | 2010-02-10 | 2011-08-25 | Kitakyushu Foundation For The Advancement Of Industry Science & Technology | Method of recovering lactide |
| JP2012144443A (en) * | 2011-01-06 | 2012-08-02 | Utsunomiya Univ | Method for producing lactide |
| JP2013504634A (en) * | 2009-09-10 | 2013-02-07 | ガラクティック・エス．エー． | Stereospecific recycling method for mixtures of PLA-based polymers |
| WO2017099109A1 (en) * | 2015-12-09 | 2017-06-15 | 東洋製罐株式会社 | Method for collecting lactide |
| JP2017105912A (en) * | 2015-12-09 | 2017-06-15 | 東洋製罐株式会社 | Method for recovering lactide |
| JP2017128517A (en) * | 2016-01-19 | 2017-07-27 | 東洋製罐株式会社 | Method for recovering lactide |
| JP2018507846A (en) * | 2015-02-13 | 2018-03-22 | ピュラック バイオケム ビー． ブイ． | Method for producing lactide |
| CN114349733A (en) * | 2022-01-10 | 2022-04-15 | 万华化学集团股份有限公司 | Method for continuously preparing high-gloss pure L, L-lactide |
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| JP2013504634A (en) * | 2009-09-10 | 2013-02-07 | ガラクティック・エス．エー． | Stereospecific recycling method for mixtures of PLA-based polymers |
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| JP2018507846A (en) * | 2015-02-13 | 2018-03-22 | ピュラック バイオケム ビー． ブイ． | Method for producing lactide |
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| JP2017128517A (en) * | 2016-01-19 | 2017-07-27 | 東洋製罐株式会社 | Method for recovering lactide |
| CN114349733A (en) * | 2022-01-10 | 2022-04-15 | 万华化学集团股份有限公司 | Method for continuously preparing high-gloss pure L, L-lactide |
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