JP3131158B2 - Apparatus and method for producing polylactic acid - Google Patents
Apparatus and method for producing polylactic acidInfo
- Publication number
- JP3131158B2 JP3131158B2 JP08258404A JP25840496A JP3131158B2 JP 3131158 B2 JP3131158 B2 JP 3131158B2 JP 08258404 A JP08258404 A JP 08258404A JP 25840496 A JP25840496 A JP 25840496A JP 3131158 B2 JP3131158 B2 JP 3131158B2
- Authority
- JP
- Japan
- Prior art keywords
- reaction
- lactic acid
- producing
- reflux
- polylactic acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Polyesters Or Polycarbonates (AREA)
- Biological Depolymerization Polymers (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、生分解プラスチッ
クとして有用なポリ乳酸の製造装置及び製造方法に関す
る。The present invention relates to an apparatus and a method for producing polylactic acid useful as a biodegradable plastic.
【０００２】[0002]
【従来の技術】乳酸を原料とするポリ乳酸は、容易に加
水分解や熱分解により環状二量体のラクチドにケミカル
リサイクルできることや、透明性や剛性が良いこと及び
他の生分解性の物質と共重合させて種々のグレード設計
が可能であるために、医療用材料のみならず、フィル
ム、ブロー繊維や一般の成形品としても注目を集めつつ
ある。2. Description of the Related Art Lactic acid-based polylactic acid is easily hydrolyzed or thermally decomposed into a cyclic dimer lactide, has good transparency and rigidity, and has good compatibility with other biodegradable substances. Since various grade designs are possible by copolymerization, attention is being paid not only to medical materials but also to films, blown fibers and general molded products.
【０００３】而して、一般にこのポリ乳酸は、環状二量
体であるラクチドを開環重合させることによって製造さ
れる。しかし、この方法はラクチド製造工程や精製工程
でのコストが多大で、最終的にポリ乳酸の製品コストを
大きくし、実用化への大きな障害になっている。そのた
め、コスト低減をねらって、乳酸モノマーを直接重縮合
させて、ポリ硫酸を製造する方法が提案されている。[0003] Generally, this polylactic acid is produced by ring-opening polymerization of lactide, which is a cyclic dimer. However, this method has a large cost in the lactide production step and the purification step, and eventually increases the product cost of polylactic acid, which is a major obstacle to practical use. Therefore, a method of producing polysulfuric acid by directly polycondensing a lactic acid monomer with the aim of reducing costs has been proposed.
【０００４】例えば最近の例では、特開平６−２９８９
１３号公報や特開平６−２９８９１４号公報にみられる
ように、回分式の反応器や、１軸、２軸の横型高粘度反
応器を用いて、ヒドロキシカルボン酸類を脱水重縮合さ
せ高分子量のポリヒドロキシカルボン酸を製造する方法
が提案されている。For example, in a recent example, Japanese Patent Laid-Open No.
No. 13 and JP-A-6-298914, hydroxycarboxylic acids are dehydrated and polycondensed using a batch reactor or a uniaxial or biaxial horizontal high-viscosity reactor to obtain a high molecular weight polymer. Methods for producing polyhydroxycarboxylic acids have been proposed.
【０００５】しかしながら、斯かる方法は重縮合反応で
副生する水や低沸点成分を系外に効率よく除去するため
に多量の溶媒を反応系に加え、副生水と共に系外に真空
ポンプで吸引し、水や低沸点成分を分離した後、溶媒を
精製して反応系に循還させるものであるため、多量の溶
媒を必要とする結果、精製、循還コストが大きいこと並
びに重合終了後に多量の溶媒が製品ポリマーに残留し、
その分離精製にコストが多大にかかること等の問題があ
った。However, in such a method, a large amount of a solvent is added to the reaction system in order to efficiently remove water and low-boiling components produced as a by-product in the polycondensation reaction outside the system, and a vacuum pump is used outside the system together with the by-product water. After suction and separation of water and low-boiling components, the solvent is purified and recycled to the reaction system.As a result, a large amount of solvent is required, resulting in high purification and recycling costs and after completion of polymerization. A large amount of solvent remains in the product polymer,
There was a problem that the separation and purification cost a lot.
【０００６】また、この乳酸モノマーからの重縮合反応
は、図１に示す如く、モノマー、プレポリマー、ラクチ
ド及びポリマーの間の反応平衡があり、特に反応溶液中
のラクチドの濃度を一定以上に保たないと、プレポリマ
ーやポリマーの解重合反応の割合が高くなる、すなわ
ち、高分子量化が進まないという難点があるところ、上
述の如き従来の技術では溶媒、ラクチド及び水を反応系
から除去するものであるため、自ずと高分子量化への速
度が小さいという問題があった。As shown in FIG. 1, the polycondensation reaction from the lactic acid monomer has a reaction equilibrium between the monomer, the prepolymer, the lactide and the polymer, and in particular, maintains the lactide concentration in the reaction solution at a certain level or more. Without it, the rate of depolymerization reaction of the prepolymer or polymer becomes high, that is, there is a difficulty that the molecular weight does not increase, but in the conventional techniques as described above, the solvent, lactide and water are removed from the reaction system. Therefore, there is a problem that the speed for increasing the molecular weight is naturally low.
【０００７】そこで、斯かる問題を解決する方法として
本願出願人は、反応系を高真空に保つ際、反応系外に排
出される水、ラクチド、溶媒及び乳酸低分子化合物のう
ち、水以外のものを還流装置で冷却液化して、還流させ
る方法を開発し、既に特許出願（特開平８−１４３６４
９号公報）している。Therefore, as a method for solving such a problem, the applicant of the present application has proposed that when keeping the reaction system at a high vacuum, water, lactide, solvent and low-molecular-weight lactic acid compound other than water are discharged out of the reaction system. A method of cooling and liquefying the product with a reflux device and refluxing it has been developed, and a patent application (JP-A-8-14364) has already been filed.
No. 9).
【０００８】しかしながら、この方法に用いられる従来
の還流装置は、図２に示す如く、冷却二重管３２の内管
にスクリュ３１あるいは邪魔板を挿入した構造のもので
あったため、ラクチド（場合によっては溶媒を含むこと
もある）及び乳酸低分子化合物を完全に液化し還流させ
ようとして、冷却媒体の温度を低くすると高い凝固点を
有するラクチド（mp＝９５−９８℃）が結晶化して、還
流管内を閉塞してしまい、溶媒や他の液体の還流が阻害
され易く、逆に、該結晶化を防止するためにラクチドの
凝固点近くまで冷却媒体の温度を上げると、還流管の中
心部分（軸直角断面での）は冷却が効かないため、溶媒
やラクチドを液化できずに、一部蒸気として系外に飛散
されてしまう傾向があった。そのため反応速度も上がら
ず、反応平衡が高分子側に行き難い結果、到達分子量も
あまり大きなものが得られないのが実状であった。However, the conventional reflux device used in this method has a structure in which the screw 31 or the baffle plate is inserted into the inner tube of the cooling double tube 32 as shown in FIG. Lactide having a high freezing point (mp = 95-98 ° C.) crystallizes when the temperature of the cooling medium is lowered in order to completely liquefy and reflux the low molecular weight compound of lactic acid and reflux. When the temperature of the cooling medium is raised to near the freezing point of lactide in order to prevent the crystallization, the central portion of the reflux tube (perpendicular to the axis) is obstructed. (In the cross section), cooling was not effective, so that the solvent and lactide could not be liquefied, and there was a tendency that some of them were scattered out of the system as vapor. As a result, the reaction rate did not increase, and the reaction equilibrium was hard to reach the polymer side, and as a result, a substance with a very high reached molecular weight could not be obtained.
【０００９】[0009]
【発明が解決しようとする課題】本発明は斯かる従来の
実状に鑑みてなされたものであり、副生水を反応系外に
留去しつつ、水以外の蒸気を均一に冷却・液化し、高収
率で反応系内に還流せしめることにより重縮合反応速度
を大きくし、反応平衡を鎖結合反応側〔図１のPoly（la
ctic acid）側〕に移行させて製品のポリ乳酸の到達分
子量を高くすると共に、プロセスを簡素化し、コストを
低減することのできるポリ乳酸の製造装置及び製造方法
を提供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional situation, and uniformly cools and liquefies steam other than water while distilling off by-product water out of the reaction system. By refluxing the reaction system with high yield, the polycondensation reaction rate was increased, and the reaction equilibrium was shifted to the chain binding reaction side [Poly (la) in FIG.
[ctic acid] side] to increase the attainable molecular weight of the polylactic acid of the product, to simplify the process, and to provide a polylactic acid production apparatus and a production method capable of reducing the cost.
【００１０】而して、本発明者は当該目的を達成すべく
反応槽の上部に設置する還流装置につき種々検討を重ね
た結果、従来のスクリュタイプや邪魔板タイプの還流装
置に代えて、あるいは更にそれに加えて、化学プラント
等の精留塔の塔頂に使用されている多管式熱交換凝縮器
を用いれば、極めて良い結果が得られることを見い出
し、本発明を完成した。The inventor of the present invention has conducted various studies on a reflux device installed on the upper portion of the reaction tank in order to achieve the object, and as a result, has been able to replace the conventional screw type or baffle plate type reflux device, or In addition, it has been found that extremely good results can be obtained by using a multitubular heat exchange condenser used at the top of a rectification column of a chemical plant or the like, and the present invention has been completed.
【００１１】[0011]
【課題を解決するための手段】すなわち本発明は、反応
槽上部に、還流装置として真空ポンプとの連結用口を有
する多管式熱交換凝縮器を取り付け設置したことを特徴
とする直接重縮合法用ポリ乳酸の製造装置により上記目
的を達成したものであり、また本発明は直接重縮合法に
より乳酸モノマーから乳酸ポリマーを製造する方法に於
て、上記製造装置を用い、真空ポンプで反応槽内を減圧
して反応を進行せしめ、反応液から蒸気として発生する
副生水、ラクチド及び乳酸の低分子化合物あるいは更に
溶媒を多管式熱交換凝縮器に導入し、副生水を反応系外
に留去しつつ、当該副生水以外を冷却・液化して反応槽
内に還流させることにより反応液内の化学平衡を鎖結合
反応側に移行させることを特徴とする重量平均分子量５
０，０００以上のポリ乳酸の製造方法により上記目的を
達成したものである。That is, the present invention is directed to a direct compaction wherein a multi-tube heat exchange condenser having a port for connection to a vacuum pump is mounted and installed as a reflux device on the upper part of a reaction tank. The above object has been achieved by an apparatus for producing a polylactic acid for legal use, and the present invention also relates to a method for producing a lactic acid polymer from a lactic acid monomer by a direct polycondensation method. The inside of the reaction system is decompressed to allow the reaction to proceed, and by-product water, low-molecular-weight compounds of lactide and lactic acid, which are generated as a vapor from the reaction solution, or a solvent is introduced into the multitubular heat exchange condenser, and the by-product water is removed from the reaction system A weight-average molecular weight of 5 characterized by shifting the chemical equilibrium in the reaction solution to the chain-bonding reaction side by cooling and liquefying the water other than the by-product water and refluxing it in the reaction tank while distilling off.
The above object has been achieved by a method for producing polylactic acid of 000 or more.
【００１２】[0012]
【発明の実施の形態】本発明に用いられる多管式熱交換
凝縮器は、筒状本体の管板に緻密に垂直配置された多数
の凝縮伝熱管を有し、反応槽から流入する伝熱管内の混
合蒸気を軸直角方向断面での温度分布を最小に抑え、蒸
気の均一冷却が可能な構造となっており、斯かる多管式
熱交換凝縮器としては例えばデフレグメーターが好まし
いものとして挙げられる。尚、本発明に於て当該多管式
熱交換凝縮器は、１台のみを設置しても良いが、冷却温
度に差をつけるため２台以上を直列状に多段設置併用す
ることもできる。DESCRIPTION OF THE PREFERRED EMBODIMENTS A multi-tube heat exchange condenser used in the present invention has a large number of condensation heat transfer tubes densely arranged vertically on a tube plate of a cylindrical main body, and heat transfer flowing from a reaction tank. The temperature distribution of the mixed steam in the pipe in the cross section perpendicular to the axis is minimized, and the structure is such that the steam can be uniformly cooled.As such a multi-tube heat exchange condenser, for example, a dephlegmator is preferable. No. In the present invention, only one multi-tube heat exchange condenser may be installed, but two or more heat-exchange condensers may be used in series in a multi-stage manner in order to make a difference in cooling temperature.
【００１３】因に、かかかる多管式熱交換凝縮器は、伝
導管の長さを充分長くすることにより、ラクチドの凝固
点付近の高い冷却温度でもラクチド、乳酸低分子化合物
あるいは更に溶媒を完全に還流させ、反応系外への飛散
を防止することができると共に、例えば冷却温度を５０
〜９０℃と少し低くしても、ラクチドの結晶は生成する
ものの、従来のスクリュタイプや邪魔板タイプと異なっ
て、当該結晶は垂直に配置された伝熱管の内壁に形成さ
れるので、溶媒（液体）や乳酸（液体）更には低分子化
合物の流下に伴って洗い流され、伝導管内が閉塞される
ことはない。In this multi-tube heat exchange condenser, the length of the conduction tube is sufficiently increased so that lactide, low-molecular-weight lactic acid or a solvent can be completely removed even at a high cooling temperature near the freezing point of lactide. By refluxing, it is possible to prevent scattering to the outside of the reaction system.
Even if the temperature is slightly lowered to ~ 90 ° C, lactide crystals are formed, but unlike the conventional screw type or baffle plate type, the crystals are formed on the inner wall of the vertically arranged heat transfer tube, so that the solvent ( (Liquid), lactic acid (Liquid), and low-molecular-weight compounds are washed away, and the inside of the conductive tube is not blocked.
【００１４】本発明に於ては、当該多管式熱交換凝縮器
と反応槽との間に、更に従来の還流装置、就中スクリュ
式還流装置を介在連結せしめ、該スクリュ式還流装置の
混合・攪拌力と表面更新力で反応液から蒸気として発生
する副生水、ラクチド及び乳酸の低分子化合物あるいは
更に溶媒を多管式熱交換凝縮器に導入し、副生水を反応
系外に留去しつつ当該副生水以外を冷却・液化してスク
リュ式還流装置を介して反応槽内に還流させれば、重量
平均分子量５０，０００以上のポリ乳酸を更に効率良く
製造する上で有利である。In the present invention, a conventional reflux device, particularly a screw reflux device, is interposed between the multi-tube heat exchange condenser and the reaction tank, and the screw reflux device is mixed.・ Introduce by-product water, low molecular weight compounds of lactide and lactic acid, which are generated as a vapor from the reaction solution by stirring power and surface renewal force, or a solvent into the multitubular heat exchange condenser, and leave the by-product water outside the reaction system. Cooling and liquefying other than the by-product water while leaving the mixture and refluxing the mixture in the reaction tank via a screw reflux device is advantageous in producing polylactic acid having a weight average molecular weight of 50,000 or more more efficiently. is there.
【００１５】尚、本発明装置は溶媒を使用しないプロセ
スにも適用でき、その場合還流させるものはラクチド及
び乳酸の低分子化合物である。The apparatus of the present invention can be applied to a process that does not use a solvent. In this case, what is refluxed is a low molecular compound of lactide and lactic acid.
【００１６】本発明に於て、当該還流は０．１〜５．０
mmHgの減圧下行なうのが好ましく、また還流温度は、重
合反応系の温度、圧力及び使用する溶媒の種類等により
適宜選定されるが、２０〜１００℃、特に溶媒を使用す
る場合には４０〜８０℃が好ましく、溶媒を使用しない
場合にはラクチドの融点を若干上まわる９５〜１００℃
が好ましい。In the present invention, the reflux is 0.1 to 5.0.
The reaction is preferably carried out under a reduced pressure of mmHg, and the reflux temperature is appropriately selected depending on the temperature of the polymerization reaction system, the pressure and the type of the solvent to be used, but is preferably 20 to 100 ° C., particularly 40 to 100 ° C. when a solvent is used. 80 ° C. is preferable, and when no solvent is used, 95 to 100 ° C. slightly higher than the melting point of lactide
Is preferred.
【００１７】[0017]
【実施例】以下実施例を示す図面に従って本発明装置を
更に説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus of the present invention will be further described below with reference to the drawings showing embodiments.
【００１８】図３は本発明装置の第一の実施例を示すも
ので、反応液４を攪拌する攪拌翼１１を備えた反応槽１
の上部に、多管式熱交換凝縮器２が取り付け設置されて
いるものである。この多管式熱交換凝縮器２は、上部に
真空ポンプ（図示せず）との連結用口２１を有する筒状
本体２２の内部に、緻密に垂直配置された多数の凝縮伝
熱管２３を有し、下部端が反応槽１内に開口せしめられ
ている。FIG. 3 shows a first embodiment of the apparatus of the present invention, in which a reaction vessel 1 provided with a stirring blade 11 for stirring a reaction solution 4 is shown.
The multi-tubular heat exchange condenser 2 is attached and installed on the upper part of. The multi-tube heat exchange condenser 2 has a plurality of condensation heat transfer tubes 23 densely arranged vertically inside a cylindrical main body 22 having a connection port 21 for connecting to a vacuum pump (not shown) at the top. The lower end is opened in the reaction tank 1.
【００１９】図４は、本発明装置の第二の実施例を示す
もので、第一の実施例（図３）の装置に於て、反応槽１
と多管式熱交換凝縮器２との間に、更に従来のスクリュ
式還流装置３が介在連結せしめられているものである。FIG. 4 shows a second embodiment of the apparatus of the present invention. In the apparatus of the first embodiment (FIG. 3), the reaction tank 1 is used.
A conventional screw-type reflux device 3 is further interposed between and the multi-tube heat exchange condenser 2.
【００２０】[0020]
【発明の効果】本発明によれば、直接重縮合法によるポ
リ乳酸の製造に於て、副生水を反応系外に留去しつつ、
水以外の蒸気を均一に冷却・液化し、高収率で反応系内
に還流せしめることができるので、重縮合反応速度を大
きくし、反応平衡を鎖結合反応側に移行せしめ、短時間
で効率良く高分子量のポリ乳酸を製造することができ
る。According to the present invention, in the production of polylactic acid by the direct polycondensation method, by-product water is distilled out of the reaction system,
Steam other than water can be uniformly cooled and liquefied, and can be refluxed into the reaction system in high yield, increasing the polycondensation reaction rate and shifting the reaction equilibrium to the side of the chain-bonding reaction. Good high molecular weight polylactic acid can be produced.
【図１】直接重縮合法によるポリ乳酸製造時の反応液中
の化学平衡を示す説明図。FIG. 1 is an explanatory diagram showing a chemical equilibrium in a reaction solution when polylactic acid is produced by a direct polycondensation method.
【図２】反応槽上部に、スクリュ式還流装置を設置した
従来のポリ乳酸製造装置の概略説明図。FIG. 2 is a schematic explanatory view of a conventional polylactic acid production apparatus in which a screw reflux device is installed above a reaction tank.
【図３】本発明装置の第一の実施例を示す概略断面説明
図。FIG. 3 is a schematic sectional explanatory view showing a first embodiment of the device of the present invention.
【図４】本発明装置の第二の実施例を示す概略断面説明
図。FIG. 4 is a schematic sectional explanatory view showing a second embodiment of the device of the present invention.
１：反応槽 ２：多管式熱交換凝縮器 ３：スクリュ式還流装置 1: reaction tank 2: multi-tube heat exchange condenser 3: screw reflux device
───────────────────────────────────────────────────── フロントページの続き (72)発明者 福島 武 広島県広島市安芸区船越南一丁目６番１ 号 株式会社日本製鋼所内 (72)発明者 橋本 憲明 広島県広島市安芸区船越南一丁目６番１ 号 株式会社日本製鋼所内 (56)参考文献 特開 平８−143649（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C08G 63/00 - 63/91 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Fukushima 1-6-1, Funakoshi Minami, Aki-ku, Hiroshima City, Hiroshima Prefecture Inside Japan Steel Works, Ltd. (72) Inventor Noriaki Hashimoto 1-chome, Funakoshi-minami, Aki-ku, Hiroshima City, Hiroshima Prefecture No. 6 No. 1 Inside Japan Steel Works, Ltd. (56) References JP-A-8-143649 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C08G 63/00-63/91
Claims (6)
プとの連結用口を有する多管式熱交換凝縮器を取り付け
設置したことを特徴とする直接重縮合法用ポリ乳酸の製
造装置。1. An apparatus for producing polylactic acid for a direct polycondensation method, wherein a multitubular heat exchange condenser having a port for connection to a vacuum pump is mounted and installed as a reflux device on the upper part of a reaction tank.
スクリュ式還流装置を介在連結せしめたことを特徴とす
る請求項１記載の直接重縮合法用ポリ乳酸の製造装置。2. Between a reaction tank and a multi-tube heat exchange condenser,
2. The apparatus for producing polylactic acid for a direct polycondensation method according to claim 1, wherein a screw-type reflux apparatus is interposed and connected.
酸ポリマーを製造する方法に於て、請求項１記載の製造
装置を用い、真空ポンプで反応槽内を減圧して反応を進
行せしめ、反応液から蒸気として発生する副生水、ラク
チド及び乳酸の低分子化合物あるいは更に溶媒を多管式
熱交換凝縮器に導入し、副生水を反応系外に留去しつ
つ、当該副生水以外を冷却・液化して反応槽内に還流さ
せることにより、反応液内の化学平衡を鎖結合反応側に
移行させることを特徴とする重量平均分子量５０，００
０以上のポリ乳酸の製造方法。3. A method for producing a lactic acid polymer from a lactic acid monomer by a direct polycondensation method, wherein the reaction is carried out by reducing the pressure in the reaction vessel with a vacuum pump using the production apparatus according to claim 1. By-product water, low-molecular-weight compounds of lactide and lactic acid, or a solvent, introduced into the multitubular heat-exchange condenser, while distilling off the by-product water out of the reaction system, and removing other than the by-product water. By cooling and liquefying and refluxing in the reaction tank, the chemical equilibrium in the reaction solution is shifted to the chain-bonding reaction side, and the weight average molecular weight is 50,000.
A method for producing zero or more polylactic acids.
酸ポリマーを製造する方法に於て、請求項２記載の製造
装置を用い、真空ポンプで反応槽内を減圧して反応を進
行せしめ、当該スクリュ式還流装置の混合・攪拌力と表
面更新力で反応液から蒸気として発生する副生水、ラク
チド及び乳酸の低分子化合物、あるいは更に溶媒を多管
式熱交換凝縮器に導入し、副生水を反応系外に留去しつ
つ、当該副生水以外を冷却・液化してスクリュ式還流装
置を介して反応槽内に還流させることにより、反応液内
の化学平衡を鎖結合反応側に移行させることを特徴とす
る重量平均分子量５０，０００以上のポリ乳酸の製造方
法。4. A method for producing a lactic acid polymer from a lactic acid monomer by a direct polycondensation method, wherein the production apparatus according to claim 2 is used to reduce the pressure in a reaction tank by a vacuum pump to allow the reaction to proceed. By-product water, low-molecular-weight compounds of lactide and lactic acid, or low-molecular-weight compounds of lactic acid or a solvent, are introduced into the multitubular heat-exchange condenser by the mixing / stirring power and the surface renewal power of the reflux system. While distilling out of the reaction system, other than the by-product water is cooled and liquefied and refluxed into the reaction tank via a screw reflux device, thereby shifting the chemical equilibrium in the reaction solution to the chain-bonding reaction side. A method for producing polylactic acid having a weight average molecular weight of 50,000 or more.
なうことを特徴とする請求項３又は４記載のポリ乳酸の
製造方法。5. The method for producing polylactic acid according to claim 3, wherein the reflux is performed under a reduced pressure of 0.1 to 5.0 mmHg.
うことを特徴とする請求項３〜５の何れか１項記載のポ
リ乳酸の製造方法。6. The method for producing polylactic acid according to claim 3, wherein the reflux is performed at a temperature of 20 to 100 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08258404A JP3131158B2 (en) | 1996-09-30 | 1996-09-30 | Apparatus and method for producing polylactic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08258404A JP3131158B2 (en) | 1996-09-30 | 1996-09-30 | Apparatus and method for producing polylactic acid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10101783A JPH10101783A (en) | 1998-04-21 |
| JP3131158B2 true JP3131158B2 (en) | 2001-01-31 |
Family
ID=17319768
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP08258404A Expired - Fee Related JP3131158B2 (en) | 1996-09-30 | 1996-09-30 | Apparatus and method for producing polylactic acid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3131158B2 (en) |
-
1996
- 1996-09-30 JP JP08258404A patent/JP3131158B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10101783A (en) | 1998-04-21 |
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