TW201827502A - Method of recovering lactide - Google Patents

Method of recovering lactide Download PDF

Info

Publication number
TW201827502A
TW201827502A TW106136818A TW106136818A TW201827502A TW 201827502 A TW201827502 A TW 201827502A TW 106136818 A TW106136818 A TW 106136818A TW 106136818 A TW106136818 A TW 106136818A TW 201827502 A TW201827502 A TW 201827502A
Authority
TW
Taiwan
Prior art keywords
lactide
condenser
line
pipeline
gas
Prior art date
Application number
TW106136818A
Other languages
Chinese (zh)
Other versions
TWI742185B (en
Inventor
伊藤卓郎
Original Assignee
日商東洋製罐股份有限公司
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by 日商東洋製罐股份有限公司 filed Critical 日商東洋製罐股份有限公司
Publication of TW201827502A publication Critical patent/TW201827502A/en
Application granted granted Critical
Publication of TWI742185B publication Critical patent/TWI742185B/en

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07DHETEROCYCLIC COMPOUNDS
    • C07D319/00Heterocyclic compounds containing six-membered rings having two oxygen atoms as the only ring hetero atoms
    • C07D319/101,4-Dioxanes; Hydrogenated 1,4-dioxanes
    • C07D319/121,4-Dioxanes; Hydrogenated 1,4-dioxanes not condensed with other rings
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/91Polymers modified by chemical after-treatment
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J11/00Recovery or working-up of waste materials
    • C08J11/04Recovery or working-up of waste materials of polymers
    • C08J11/10Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
    • C08J11/12Recovery 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 dry-heat treatment only
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J11/00Recovery or working-up of waste materials
    • C08J11/04Recovery or working-up of waste materials of polymers
    • C08J11/10Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
    • C08J11/16Recovery 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
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00Technologies for solid waste management
    • Y02W30/50Reuse, recycling or recovery technologies
    • Y02W30/62Plastics recycling; Rubber recycling

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
  • Polyesters Or Polycarbonates (AREA)
  • Biological Depolymerization Polymers (AREA)
  • Heterocyclic Compounds That Contain Two Or More Ring Oxygen Atoms (AREA)

Abstract

A method of recovering the lactide by holding a resin mixture that contains the lactide under a reduced pressure, gasifying the lactide contained in the resin mixture, and introducing a gaseous mixture containing the gaseous lactide into a condensation line A while executing the vacuuming, wherein the condensation line A includes a plurality of condensers 71, 73, 75 arranged in series such that the cooling temperature decreases successively, and the lactide as well as impurities other than the lactide are separated from the gaseous mixture through the condensers.

Description

乳酸交酯回收方法Method for recycling lactide

本發明係關於回收樹脂混合物中含有之乳酸交酯的方法。The present invention relates to a method for recovering lactide contained in a resin mixture.

藉由細菌或真菌類排出體外之酵素的作用來腐化的生物分解性塑膠作為解決近年來塑膠廢棄物隨著塑膠使用量增加而異常增加之手段受到注目。在如此之生物分解性塑膠中,作為工業地量產而容易取得並對環境亦良好之脂肪族聚酯,聚乳酸受到注目,且已有在大範圍之領域中使用的各種提案。Biodegradable plastics that are decomposed by the action of bacteria or fungi that excrete enzymes have attracted attention as a means to solve the abnormal increase in plastic waste with the increase in the use of plastic in recent years. Among such biodegradable plastics, polylactic acid has attracted attention as an aliphatic polyester which is easily obtained in industrial mass production and is also environmentally friendly, and various proposals have been made for use in a wide range of fields.

聚乳酸(PLA)係以玉米等之穀物澱粉為原料之樹脂,且係以澱粉之乳酸發酵物、L-乳酸及D-乳酸為單體之直接聚縮合的聚合物,及藉由其二聚物之乳酸交酯的開環聚合製成的聚合物等。為藉由存在自然界之微生物分解成水及二氧化碳,該聚合物亦著眼於生物之完全循環系統型的樹脂。Polylactic acid (PLA) is a resin based on corn starch and other raw materials, and is a polymer of direct polycondensation using starch lactic acid fermentation product, L-lactic acid and D-lactic acid as monomers, and dimerization by the same. Polymers made from ring-opening polymerization of lactide. In order to decompose into water and carbon dioxide by microorganisms existing in nature, the polymer also focuses on biologically-circulating resins.

最近,作為聚乳酸之再循環系統,最受到注目的是可分解聚乳酸再利用之化學再循環法。該方法藉由在解聚合用觸媒存在下加熱聚乳酸進行解聚合,接著使獲得之乳酸交酯再開環聚合而形成聚乳酸並再利用。Recently, as a recycling system of polylactic acid, the chemical recycling method which can be used to decompose polylactic acid for reuse has attracted the most attention. In this method, polylactic acid is depolymerized by heating polylactic acid in the presence of a depolymerization catalyst, and then the obtained lactide is re-opened and polymerized to form polylactic acid and reused.

適用如此化學再循環之由聚乳酸回收乳酸交酯的裝置已有例如專利文獻1及2之提案。在該等專利文獻提出之裝置中,聚乳酸與解聚合用觸媒及載體樹脂投入雙軸擠出機而熔融混合,並藉由雙軸擠出機中之螺桿搬送熔融混合物至排氣室(排氣區域),接著藉由聚乳酸之解聚合產生之乳酸交酯在該排氣室氣化並與其他成分分離而回收。即,藉由聚乳酸之解聚合產生的乳酸交酯(分子量M=144),因為標準大氣壓下之沸點高達255℃,所以在大氣壓條件下難以分離。因此,藉由供給包含藉由聚乳酸之解聚合產生的乳酸交酯及解聚合用觸媒的熔融混合物至保持於減壓下之排氣室中,可降低乳酸交酯之沸點,使乳酸交酯氣化而回收。Apparatuses for recovering lactide from polylactic acid for such chemical recycling have been proposed, for example, in Patent Documents 1 and 2. In the devices proposed by these patent documents, the polylactic acid, the depolymerization catalyst, and the carrier resin are put into a biaxial extruder and melt-mixed, and the molten mixture is transferred to the exhaust chamber by the screw in the biaxial extruder ( Exhaust area), and then the lactide produced by the depolymerization of polylactic acid is vaporized in the exhaust chamber and separated from other components to be recovered. That is, lactide (molecular weight M = 144) produced by the depolymerization of polylactic acid has a boiling point of 255 ° C under standard atmospheric pressure, so it is difficult to separate it under atmospheric pressure. Therefore, by supplying a molten mixture containing a lactide produced by the depolymerization of polylactic acid and a depolymerization catalyst to an exhaust chamber maintained under reduced pressure, the boiling point of lactide can be reduced and the lactide can be crosslinked. The ester is recovered by gasification.

在如此回收裝置中實施之乳酸交酯回收方法中,氣化之乳酸交酯雖然藉由在冷凝器中之冷卻阱產生由氣體至液體之相轉換,並接著形成液體而回收,但投入大量聚乳酸,進行回收大量乳酸交酯之工業實施時,容易產生配管堵塞,因此需要定期之配管清洗等。即,因為暫時回到大氣壓進行配管清洗,然後回到預定真空度,所以有耗費時間且難以連續工作之問題。異物附著堆積於配管之彎曲部分或凹部分等的情形特別地顯著。 此外,雖然本發明人先前已提出使藉由解聚合聚乳酸產生之乳酸交酯氣化而回收的方法(請參照日本特願2015-240041號、日本特願2016-015501號、日本特願2016-007553號),但未檢討如上所述之配管堵塞等。 [先前技術文獻] [專利文獻]In the lactide recovery method implemented in such a recovery device, although gasified lactide is converted from a gas to a liquid by a cooling trap in a condenser, and then formed into a liquid to be recovered, a large amount of polymerization is invested. Lactic acid is industrially implemented to recover a large amount of lactide, and it is easy to cause piping clogging. Therefore, regular piping cleaning is required. That is, since the pipe pressure is temporarily returned to atmospheric pressure for piping cleaning, and then returned to a predetermined vacuum degree, there is a problem that it is time-consuming and difficult to continuously work. The case where foreign matter adheres to a curved portion or a concave portion of the piping and the like is particularly remarkable. In addition, although the present inventors have previously proposed a method for gasifying and recovering lactide produced by depolymerizing polylactic acid (see Japanese Patent Application No. 2015-240041, Japanese Patent Application No. 2016-015501, Japanese Patent Application No. 2016 -007553), but the piping clogging and the like described above have not been reviewed. [Prior Art Literature] [Patent Literature]

[專利文獻1]日本特開2010-126490號公報 [專利文獻2]日本專利5051729號公報[Patent Document 1] Japanese Patent Laid-Open No. 2010-126490 [Patent Document 2] Japanese Patent No. 5051729

[發明所欲解決的問題][Problems to be solved by the invention]

因此,本發明之目的在於提供使樹脂混合物中含有之乳酸交酯氣化並使用冷凝器使氣化之乳酸交酯液化而回收時,可有效地抑制配管堵塞之問題的回收方法。 本發明之另一目的在於提供可在不停止乳酸交酯回收製程之情形下進行乳酸交酯回收管線中之配管清洗的乳酸交酯回收方法。 [解決問題的手段]Therefore, an object of the present invention is to provide a recovery method which can effectively suppress the problem of piping clogging when the lactide contained in the resin mixture is vaporized and the vaporized lactide is recovered by liquefying using a condenser. Another object of the present invention is to provide a lactide recovery method capable of cleaning pipes in a lactide recovery line without stopping the lactide recovery process. [Means to solve the problem]

本發明人對使氣化之乳酸交酯液化而回收時產生之配管堵塞進行許多實驗,結果發現包含氣化之乳酸交酯的氣體混合物中含有的低分子量成分成為主要原因,產生配管堵塞或在配管內之異物附著堆積的知識,因此完成本發明。The present inventors conducted many experiments on the clogging of the piping generated when the vaporized lactide was recovered by liquefaction, and found that the low molecular weight components contained in the gas mixture containing the vaporized lactide became the main cause. The present invention has completed the knowledge of foreign matter adhesion and accumulation in the piping.

依據本發明,提供乳酸交酯回收方法,該方法係在減壓下保持包含乳酸交酯之樹脂混合物,並使該樹脂混合物中含有之乳酸交酯氣化,接著一面真空抽吸包含氣體狀乳酸交酯之氣體混合物,一面導入冷凝管線而回收乳酸交酯,其特徵為: 前述冷凝管線以冷卻溫度依序降低之方式串聯地排列多數冷凝器,且藉由該等冷凝器由前述氣體混合物捕集乳酸交酯及分離乳酸交酯以外之不純物。According to the present invention, a method for recovering lactide is provided. The method is to maintain a resin mixture containing lactide under reduced pressure, vaporize the lactide contained in the resin mixture, and then vacuum suction the gas containing lactic acid. The lactide gas mixture is introduced into the condensing line to recover lactide, which is characterized in that: the above-mentioned condensing line arranges a plurality of condensers in series so that the cooling temperature is sequentially reduced, and the condensers are captured by the foregoing gas mixture through the condenser Collection of lactide and separation of impurities other than lactide.

在本發明之乳酸交酯回收方法中,可較佳地進行以下對應之道。 (1)前述乳酸交酯係藉由聚乳酸之解聚合產生。 (2)使前述氣體混合物通過用以去除乳酸寡聚物成分之氣液分離塔,並連續地導入前述冷凝管線。 (3)依序配置第一冷凝器、第二冷凝器及第三冷凝器作為前述多數冷凝器。 (4)在0.1至8kPaA之真空度範圍內真空抽吸前述氣體混合物。 (5)將第一冷凝器之熱交換溫度設定在60至140℃。 (6)前述冷凝管線包含:用以將前述氣體混合物導入該冷凝管線之導入管線;及連接於用以真空抽吸之真空泵的終結管線,且更具有在該導入管線與該終結管線間透過切換閥分支的並聯管線,而該並聯管線中以包含至少位於最下游側之冷凝器的方式分別設有至少1個冷凝器, 真空抽吸清洗管線透過切換閥分別地連結於前述並聯管線之分支的流路。 (7)使前述氣體混合物流入前述並聯管線之分支中的一流路來進行乳酸交酯之回收,同時使連接於前述並聯管線之分支中的另一流路的前述真空抽吸清洗管線動作來進行真空清洗。 (8)在前述導入管線中配置第一冷凝器,且在前述並聯管線之分支的流路中分別地配置剩餘之冷凝器。 [發明的功效]In the lactide recovery method of the present invention, the following correspondence can be preferably performed. (1) The aforementioned lactide is produced by the depolymerization of polylactic acid. (2) The gas mixture is passed through a gas-liquid separation column for removing a lactic acid oligomer component, and is continuously introduced into the condensation line. (3) The first condenser, the second condenser, and the third condenser are sequentially arranged as the foregoing majority of condensers. (4) Vacuum suck the aforementioned gas mixture in a vacuum range of 0.1 to 8 kPaA. (5) The heat exchange temperature of the first condenser is set at 60 to 140 ° C. (6) The condensation line includes: an introduction line for introducing the gas mixture into the condensation line; and a termination line connected to a vacuum pump for vacuum suction, and further having a switching between the introduction line and the termination line The valve is connected to a parallel pipeline, and at least one condenser is provided in the parallel pipeline so as to include a condenser located at least on the most downstream side. The vacuum suction and cleaning pipeline is respectively connected to the branch of the parallel pipeline through a switching valve. Flow path. (7) The aforementioned gas mixture is allowed to flow into the first-stage path in the branch of the parallel pipeline to recover lactide, and at the same time, the vacuum suction and cleaning pipeline connected to another flow path in the branch of the parallel pipeline is operated to perform vacuum. Cleaning. (8) A first condenser is arranged in the introduction line, and the remaining condensers are separately arranged in the branched flow paths of the parallel lines. [Effect of the invention]

在本發明之乳酸交酯回收方法中,雖然包含氣化之乳酸交酯的氣體混合物導入冷凝管線中,且在該冷凝管線液化並回收氣體狀乳酸交酯,但該冷凝管線具有串聯地排列之多數冷凝器,且多數冷凝器配置成冷卻溫度依序降低。即,在開始之冷凝器中液化並回收氣體狀乳酸交酯,接著藉由後來之冷凝器液化並去除分子量比乳酸交酯低之異物(不可避免之不純物)。因此,可有效地抑制低分子量異物累積在配管內之類的問題,藉此可有效地防止配管堵塞,及使用於真空抽吸之真空泵動作不良等。In the lactide recovery method of the present invention, although a gas mixture containing vaporized lactide is introduced into a condensation line, and gaseous lactide is liquefied and recovered in the condensation line, the condensation line has Most condensers, and most condensers are configured such that the cooling temperature is sequentially reduced. That is, gaseous lactide is liquefied and recovered in the initial condenser, and then foreign matter (unavoidable impurities) having a molecular weight lower than that of lactide is removed and removed by the subsequent condenser. Therefore, problems such as accumulation of low-molecular-weight foreign matter in the piping can be effectively suppressed, thereby effectively preventing clogging of the piping and malfunction of the vacuum pump used for vacuum suction.

此外,在本發明中,形成透過切換閥使上述冷凝管線分支之並聯管線,可將冷凝器分別設置在並聯管線中。在如此之態樣中,可使並聯管線中之一並聯管線作動,進行氣化乳酸交酯之液化及低分子量異物之去除,同時在另一並聯管線中連結流過清洗用之氣體的清洗管線,進行清洗作業。即,可在不停止回收液化氣體狀乳酸交酯及去除低分子量異物之情形下進行管線之清洗。藉此,可特別有效率地連續回收乳酸交酯,因此對回收大量乳酸交酯之工業實施極有利。In addition, in the present invention, a parallel pipeline that branches the above-mentioned condensation pipeline through a switching valve is formed, and the condensers can be installed in the parallel pipelines, respectively. In such a state, one of the parallel lines can be operated to perform the liquefaction of gasified lactide and the removal of low-molecular-weight foreign substances, and at the same time, the other parallel line is connected to a cleaning line through which the cleaning gas flows. For cleaning operations. That is, the pipeline can be cleaned without stopping the recovery of liquefied gaseous lactide and removing low-molecular-weight foreign matters. This makes it possible to recover the lactide continuously in a particularly efficient manner, which is extremely advantageous for the industrial implementation of recovering a large amount of lactide.

參照圖1,說明使用於實施本發明之乳酸交酯回收方法的回收裝置。大致而言,本回收裝置由擠出機(熔融混合裝置)1、連接於擠出機1之排氣室3、位於排氣室3之下方的載體樹脂回收室4、連接於排氣室3之捕集裝置5及連接於載體樹脂回收室之載體樹脂排出用擠出機6構成。捕集裝置5具有氣液分離塔51及冷凝管線A,冷凝管線A連接於真空抽吸用之真空泵7。即,藉由驅動真空泵7,排氣室3可保持在預定減壓度。With reference to Fig. 1, a recovery device used for carrying out the lactide recovery method of the present invention will be described. Generally speaking, the recovery device is composed of an extruder (melt mixing device) 1, an exhaust chamber 3 connected to the extruder 1, a carrier resin recovery chamber 4 located below the exhaust chamber 3, and connected to the exhaust chamber 3. The collection device 5 and the carrier resin discharge extruder 6 connected to the carrier resin recovery chamber are configured. The capture device 5 includes a gas-liquid separation tower 51 and a condensing line A. The condensing line A is connected to a vacuum pump 7 for vacuum suction. That is, by driving the vacuum pump 7, the exhaust chamber 3 can be maintained at a predetermined pressure reduction degree.

在本發明中,首先,使用如此之回收裝置,將聚乳酸、解聚合用觸媒及載體樹脂投入擠出機1之加料漏斗,接著在擠出機1之缸內熔融混合,使聚乳酸解聚合。然後,將熔融混合物供給至排氣室3,並在該排氣室3中,使藉由聚乳酸之解聚合產生之乳酸交酯氣化。氣化之乳酸交酯導入連接於排氣室3之捕集裝置5。在捕集裝置5中,藉由氣液分離塔51去除高分子量成分(例如,寡聚物),接著,藉由在冷凝管線A中之冷卻,氣化之乳酸交酯形成液體而回收。此外,載體樹脂由排氣室3下方之載體樹脂回收室4通過載體樹脂排出用擠出機6排出。In the present invention, first, using such a recovery device, polylactic acid, a catalyst for depolymerization, and a carrier resin are charged into a feeding funnel of the extruder 1, and then melt-mixed in a cylinder of the extruder 1 to decompose the polylactic acid. polymerization. Then, the molten mixture is supplied to the exhaust chamber 3, and in this exhaust chamber 3, lactide generated by the depolymerization of polylactic acid is vaporized. The vaporized lactide is introduced into a capture device 5 connected to the exhaust chamber 3. In the capture device 5, high-molecular-weight components (for example, oligomers) are removed by the gas-liquid separation column 51, and then, the gasified lactide is formed into a liquid by cooling in the condensation line A and recovered. The carrier resin is discharged from the carrier resin recovery chamber 4 below the exhaust chamber 3 through the carrier resin discharge extruder 6.

使用於回收乳酸交酯之聚乳酸可使用由市場回收品(消費後回收品(Post Consumer))及樹脂加工製造工廠等排出之產業廢棄物,或在聚乳酸樹脂之製造步驟中產生之規格不符樹脂等。此外,可為混合L-聚乳酸(PLLA)及D-聚乳酸(PDLA)之立體複合型者,亦可為分子鏈中之L-乳酸單位及D-乳酸單位混合之中間型者。當然,亦可為原生聚乳酸。 此外,使用之聚乳酸係組合少量共聚合單位組合者,例如,以50莫耳%以上係乳酸單位為條件,可包含乳酸交酯及來自可共聚合之內酯類、環狀醚類、環狀醯胺類、各種醇類、羧酸類等之單位。Polylactic acid used for recycling lactide can use industrial waste discharged from market recycled products (Post Consumer) and resin processing and manufacturing plants, or the specifications generated during the manufacturing steps of polylactic acid resin are not consistent Resin, etc. In addition, it may be a three-dimensional composite type in which L-polylactic acid (PLLA) and D-polylactic acid (PDLA) are mixed, or an intermediate type in which L-lactic acid units and D-lactic acid units are mixed in a molecular chain. Of course, it may be native polylactic acid. In addition, if a polylactic acid-based combination is used with a small amount of copolymerized unit combinations, for example, under the condition that 50 mol% or more of lactic acid units are used, it may include lactide and copolymerizable lactones, cyclic ethers, and cyclic It is a unit of amidines, various alcohols, and carboxylic acids.

雖然最好使用代表之MgO作為聚乳酸之解聚合用觸媒,但亦可使用CaO、SrO、BaO等之鹼土族金屬氧化物等。此外,亦可較佳地使用聚合觸媒使用之異辛酸亞錫(Tin(II)2-ethyl hexanoate)及作為阻燃劑之氫氧化鋁(Al(OH)3 )等。另外,亦可混合該等觸媒來使用。該解聚合用觸媒使聚乳酸之解聚合溫度降低,且藉由使用解聚合用觸媒,可促進聚乳酸之熱分解,進行聚乳酸之低分子量化,例如擠出機1之加料漏斗投入時具有大約20萬之分子量的聚乳酸可分解到乳酸交酯(分子量144)。此外,MgO及鋁系觸媒等亦具有抑制熱反應時之消旋性(光學異性化反應)現象的效果。Although it is preferable to use representative MgO as a catalyst for depolymerization of polylactic acid, alkaline earth metal oxides such as CaO, SrO, and BaO may also be used. In addition, stannous isooctanoate (Tin (II) 2-ethyl hexanoate) used for the polymerization catalyst and aluminum hydroxide (Al (OH) 3 ) as a flame retardant can also be preferably used. In addition, these catalysts may be used in combination. This depolymerization catalyst lowers the depolymerization temperature of polylactic acid, and by using the depolymerization catalyst, the thermal decomposition of polylactic acid can be promoted to reduce the molecular weight of polylactic acid, such as the addition of the feeding funnel of extruder 1 Polylactic acid having a molecular weight of about 200,000 can be decomposed into lactide (molecular weight 144). In addition, MgO, aluminum-based catalysts, and the like also have the effect of suppressing the racemization (optical anisotropic reaction) phenomenon during thermal reactions.

上述聚乳酸之解聚合用觸媒通常每100質量份之聚乳酸,使用0.05至5質量份之量。The polylactic acid catalyst for depolymerization is usually used in an amount of 0.05 to 5 parts by mass per 100 parts by mass of the polylactic acid.

載體樹脂使用於用螺桿搬送聚乳酸之熔融物,同時具有作為在擠出機之缸筒與螺桿間之密封材的機能。The carrier resin is used for conveying the melt of polylactic acid by a screw, and has a function as a sealing material between the cylinder of the extruder and the screw.

即,包含乳酸交酯之聚乳酸雖然會因其分子量而不同,但大體上熔融黏度比一般之聚合物低很多,因此螺桿之聚乳酸熔融物搬送效率不佳,恐有螺桿成為接近空轉狀態之虞。因此,藉由併用載體樹脂,提高擠出機中之包含乳酸熔融物的熔融樹脂黏性,可更有效率地用螺桿搬送聚乳酸之熔融物。 此外,因為載體樹脂之熔融黏度比包含乳酸交酯之聚乳酸高,所以藉由用某程度以上之量使用載體樹脂與聚乳酸混合,可一面維持熔融混合物充滿擠出機之缸內面與螺桿間的空隙,一面用螺桿搬送該熔融混合物。即,藉由使用載體樹脂,缸內面與螺桿間之空隙可經常保持密封狀態,藉此,可效地進行排氣室3之減壓。 另外,即使是熔融黏度低之載體樹脂時,若為具有比PLA之解聚合溫度高的熱分解溫度的樹脂(PET、PC、PS等),因為其本身未熱分解,所以可使用螺桿搬送聚乳酸及其解聚合物(前進)。That is, although polylactic acid containing lactide may vary depending on its molecular weight, its melt viscosity is generally much lower than that of ordinary polymers. Therefore, the polylactic acid melt of the screw has a poor transfer efficiency, and there is a fear that the screw will become close to the idle state. Yu. Therefore, by using the carrier resin in combination, the viscosity of the molten resin containing the molten lactic acid in the extruder is increased, and the molten polylactic acid can be more efficiently transported by the screw. In addition, because the carrier resin has a higher melt viscosity than polylactic acid containing lactide, by using the carrier resin and polylactic acid in a certain amount or more, it is possible to maintain the molten mixture to fill the inner surface of the cylinder and the screw of the extruder. The molten mixture was conveyed by a screw while the space was between. That is, by using the carrier resin, the space between the cylinder inner surface and the screw can always be kept in a sealed state, thereby effectively reducing the pressure of the exhaust chamber 3. In addition, even if it is a carrier resin with a low melt viscosity, if it is a resin (PET, PC, PS, etc.) having a higher thermal decomposition temperature than the depolymerization temperature of PLA, it is not thermally decomposed by itself, so it can be transported by screw Lactic acid and its depolymerization (advance).

如此之載體樹脂不會對聚乳酸之解聚合產生不良影響,且只要不對藉由聚乳酸之解聚合產生之乳酸交酯顯示反應性,可使用各種熱可塑性樹脂。一般而言,雖然較佳地使用聚乙烯、聚丙烯等之烯烴系樹脂,但亦可較佳地使用聚對苯二甲酸乙二酯(PET)等之聚酯樹脂、聚碳酸酯(PC)等之聚酯及聚苯乙烯(PS)等之苯乙烯樹脂等。此外,該等樹脂使用具有充分發揮上述機能之分子量且具有充分之熔融黏度者。Such a carrier resin does not adversely affect the depolymerization of polylactic acid, and as long as it does not show reactivity to the lactide produced by the depolymerization of polylactic acid, various thermoplastic resins can be used. In general, although olefin resins such as polyethylene and polypropylene are preferably used, polyester resins such as polyethylene terephthalate (PET) and polycarbonate (PC) can also be preferably used. Such as polyester and styrene resin such as polystyrene (PS). In addition, for these resins, those having a molecular weight sufficiently exhibiting the above functions and having sufficient melt viscosity are used.

在本發明中,上述載體樹脂通常依據裝置之規格等設定在適當之量範圍內。例如,每100質量份之聚乳酸,大約20至10000質量份,而更佳的是20至100質量份,且設定為可確保螺桿搬送性及真空密封性之量。In the present invention, the above-mentioned carrier resin is usually set within an appropriate amount range in accordance with the specifications and the like of the device. For example, it is about 20 to 10,000 parts by mass per 100 parts by mass of polylactic acid, and more preferably 20 to 100 parts by mass, and is set to an amount that can secure screw conveyance and vacuum tightness.

上述聚乳酸、解聚合用觸媒及載體樹脂由擠出機1之加料漏斗投入其預定量,並在該擠出機1之缸內熔融混合。 即,藉由設置成覆蓋擠出機1之缸的加熱器(未圖示)加熱缸內部,並藉由在缸內部移動之螺桿,一面攪拌及搬送,一面進行熔融混合,在250℃以上之溫度使聚乳酸解聚合。擠出機1通常使用具有2根以上之螺桿的雙軸擠出機,並將缸內部加熱至250℃至350℃來進行熔融混合,而隨著該熔融混合,聚乳酸開始解聚合,並進行聚乳酸之低分子量化。The polylactic acid, the catalyst for depolymerization, and the carrier resin are put into a predetermined amount from the feeding funnel of the extruder 1 and melt-mixed in the cylinder of the extruder 1. That is, the inside of the cylinder is heated by a heater (not shown) provided to cover the cylinder of the extruder 1, and the screw is moved inside the cylinder while being melted and mixed while being stirred and transported at a temperature of 250 ° C or higher. Temperature depolymerizes polylactic acid. The extruder 1 usually uses a twin-screw extruder having two or more screws, and heats the inside of the cylinder to 250 ° C to 350 ° C for melt mixing. With the melt mixing, the polylactic acid starts to depolymerize and proceeds. Low molecular weight of polylactic acid.

雖然藉由上述熔融混合進行聚乳酸之低分子量化,獲得形成聚乳酸之基本單位的乳酸交酯(乳酸二聚物),但因為該乳酸交酯之標準大氣壓下的沸點為255℃,所以在此狀態下,難以進行沸點高且穩定之氣體捕集。即,乳酸交酯在液狀之原本狀態下,無法有效地且穩定地進行與熔融載體樹脂之分離,因此必須將該熔融混合物導入保持在減壓狀態之排氣室3內,藉此使乳酸交酯之沸點下降,促進氣化。Although the polylactic acid is reduced in molecular weight by the above-mentioned melt mixing to obtain a basic unit of polylactic acid, lactide (lactic acid dimer), the boiling point of the lactide at the standard atmospheric pressure is 255 ° C. In this state, it is difficult to perform stable gas capture with a high boiling point. In other words, lactide cannot be effectively and stably separated from the molten carrier resin in its liquid state. Therefore, it is necessary to introduce the molten mixture into the exhaust chamber 3 which is maintained under a reduced pressure, so as to make lactic acid. The boiling point of lactide decreases, which promotes gasification.

與圖1一起參照圖2來說明,排氣室3具有第一螺桿搬送路11,且該第一螺桿搬送路11之下方配置載體樹脂回收室4,同時由第一螺桿搬送路11朝上方直立之側壁13的上部連結連接於捕集裝置5之捕集管15。 此外,該排氣室3之頂壁17具有傾斜構造,且觀察窗19安裝在該傾斜之部份上,因此可由該觀察窗19經常觀察排氣室3之內部,特別是第一螺桿搬送路11之狀態。 另外,上述觀察窗19之下方端部延伸到由第一螺桿搬送路11朝上方直立之側壁13的外側部分,且其下側設有回流液之收納槽21。即,該收納槽21藉由上述側壁13與第一螺桿搬送路11區隔,因此回流液可不混入螺桿搬送路11中。Explained with reference to FIG. 2 together with FIG. 1, the exhaust chamber 3 has a first screw conveying path 11, and a carrier resin recovery chamber 4 is arranged below the first screw conveying path 11, and the first screw conveying path 11 is upright at the same time The upper portion of the side wall 13 is connected to the collection tube 15 of the collection device 5. In addition, the top wall 17 of the exhaust chamber 3 has an inclined structure, and the observation window 19 is installed on the inclined portion, so the observation window 19 can often observe the inside of the exhaust chamber 3, especially the first screw conveying path. 11 of the state. In addition, the lower end portion of the observation window 19 extends to an outer portion of the side wall 13 which is erected upward by the first screw conveying path 11, and a storage tank 21 for a return liquid is provided on the lower side thereof. That is, since the storage tank 21 is separated from the first screw conveyance path 11 by the side wall 13 described above, the reflux liquid can be prevented from being mixed into the screw conveyance path 11.

在如此構造之排氣室3中,第一螺桿搬送路11係由:朝同方旋轉之一對第一搬送螺桿23a、23b;適當配置在其中一第一搬送螺桿23a之上部的落回螺桿25;及收容第一搬送螺桿23a、23b的缸壁(缸筒)27構成。In the exhaust chamber 3 thus constructed, the first screw conveying path 11 is composed of: one pair of first conveying screws 23a, 23b rotating toward the same direction; and a return screw 25 appropriately disposed above one of the first conveying screws 23a. ; And a cylinder wall (cylinder tube) 27 that houses the first transfer screws 23a and 23b.

上述缸壁27係擠出機1之缸壁延長伸出者,同樣地,第一搬送螺桿23a、23b係擠出機1之螺桿延長者,且前述熔融混合物由擠出機1搬送至圖2之紙面前而可導入排氣室3內。 此外,適當配置之落回螺桿25選擇地設於排氣室3內,並設置成與第一搬送螺桿23a結合且朝與搬送螺桿23a相反之方向(在咬入位置為同方向)旋轉。The cylinder wall 27 is the cylinder wall extension of the extruder 1. Similarly, the first transfer screws 23a and 23b are the screw extensions of the extruder 1, and the molten mixture is transferred from the extruder 1 to FIG. The paper can be introduced into the exhaust chamber 3 in front of the paper. In addition, an appropriately arranged return screw 25 is selectively provided in the exhaust chamber 3, and is provided to be combined with the first conveying screw 23a and rotated in a direction opposite to the conveying screw 23a (the same direction at the biting position).

即,排氣室3係藉由真空泵7之真空抽吸來減壓。此外,藉由安裝在缸壁27上之加熱器(未圖示),第一螺桿搬送路11內與擠出機1內之缸部分同樣地加熱至大約250℃至350℃。藉此,藉由解聚合第一螺桿搬送路11內延伸之上述第一搬送螺桿23a、23b導入排氣室3內之熔融混合物含有的聚乳酸而生成的乳酸交酯氣化,且氣化之乳酸交酯由上述捕集管15導入捕集裝置5。That is, the exhaust chamber 3 is decompressed by the vacuum suction of the vacuum pump 7. In addition, a heater (not shown) mounted on the cylinder wall 27 heats the inside of the first screw conveying path 11 to approximately 250 ° C to 350 ° C similarly to the cylinder portion in the extruder 1. Thereby, the lactide produced by depolymerizing the polylactic acid contained in the molten mixture introduced into the exhaust chamber 3 by the first conveying screws 23a, 23b extending in the first screw conveying path 11 is gasified and gasified. The lactide is introduced into the collection device 5 through the collection tube 15.

此外,因為螺桿搬送之熔融混合物含有蒸氣壓高之聚乳酸解聚合物,且一面被壓縮,一面導入減壓之排氣室3內,所以在該排氣室3內膨脹,並產生由螺桿23a、23b浮起狀態之樹脂塊30。因此,該回收裝置連續運轉時,在排氣室3內連續地產生由一對第一搬送螺桿23a、23b浮起之樹脂塊30。該樹脂塊30主要是由載體樹脂形成之痂殼,且該樹脂塊30成長而增大時,只成為妨礙乳酸交酯氣體回收之閉塞物,或飛散之樹脂塊30通過捕集管15而進入捕集裝置5內,因此閉塞捕集管15全體。即,樹脂塊30引起排氣堵塞(vent-up)。In addition, since the molten mixture conveyed by the screw contains a polylactic acid polymer having a high vapor pressure and is compressed while being introduced into the decompressed exhaust chamber 3, it expands in the exhaust chamber 3 and generates a screw 23a. , 23b resin block 30 in a floating state. Therefore, when the recovery device is continuously operated, the resin block 30 floating up by the pair of first transfer screws 23a and 23b is continuously generated in the exhaust chamber 3. The resin block 30 is mainly a shell made of a carrier resin, and when the resin block 30 grows and grows, it only becomes an obstruction that prevents the recovery of lactide gas, or the scattered resin block 30 enters through the collection tube 15 The inside of the collection device 5 therefore blocks the entire collection tube 15. That is, the resin block 30 causes vent-up.

設於上述第一搬送螺桿23a之上側的落回螺桿25,如由圖2所理解地,設置成朝與第一搬送螺桿23a相反之方向旋轉。因此,由第一螺桿搬送路11浮起之狀態的樹脂塊30藉由該落回螺桿25再返回第一搬送螺桿23a上,接著落下至第二螺桿搬送路60,並與載體樹脂一起排出。 如此,落回螺桿25具有作為用以使樹脂塊30返回第一螺桿搬送路11之返回構件的機能,藉此,可抑制樹脂塊30之成長,因此可有效防止因樹脂塊30之成長而產生的問題。The return screw 25 provided on the upper side of the first transfer screw 23a is provided to be rotated in a direction opposite to the first transfer screw 23a as understood from FIG. 2. Therefore, the resin block 30 in a state of being floated by the first screw conveying path 11 is returned to the first conveying screw 23a by the return screw 25, and then falls to the second screw conveying path 60, and is discharged together with the carrier resin. In this way, the return screw 25 has a function as a return member for returning the resin block 30 to the first screw conveying path 11, thereby suppressing the growth of the resin block 30, and thus effectively preventing the resin block 30 from being generated due to the growth of the resin block 30. The problem.

上述作為返回構件使用之落回螺桿25的旋轉可為與第一搬送螺桿23a、23b同步之旋轉,亦可為不同步之旋轉。 此外,只要可使由螺桿搬送路11浮起之樹脂塊30返回螺桿搬送路11,亦可使用落回螺桿25以外之構件作為返回構件。例如,亦可較佳地使用以不妨礙由藉由第一搬送螺桿23a、23b搬送之熔融混合物氣化並流入捕集管15之乳酸交酯流路且覆蓋第一搬送螺桿23a及/或23b之上方的方式,配置多數槳葉狀返回構件及以橢圓形葉片取代螺旋葉片之旋轉軸等作為返回構件。The rotation of the return screw 25 used as the return member may be a rotation synchronized with the first conveying screws 23a, 23b, or may be an asynchronous rotation. In addition, as long as the resin block 30 floating from the screw conveyance path 11 can be returned to the screw conveyance path 11, a member other than the return screw 25 may be used as the return member. For example, it can be preferably used so as not to prevent the molten mixture conveyed by the first conveying screws 23a and 23b from vaporizing and flowing into the lactide flow path of the collecting pipe 15 and covering the first conveying screws 23a and / or 23b. In the above method, a large number of paddle-shaped return members and an elliptical blade instead of a rotary shaft of a spiral blade are arranged as return members.

此外,雖然氣體之乳酸交酯接觸觀察窗19等而冷卻並再液化(即,回流)時,產生排氣堵塞,但在如上述構造之排氣室3中可有效地防止因乳酸交酯之回流液而產生的問題。 即,藉由第一螺桿搬送路11將包含聚乳酸、解聚合用觸媒及載體樹脂之熔融混合物由擠出機1導入排氣室3並連續進行乳酸交酯之氣化時,有時在觀察窗19之面產生凝結之液滴31(即,回流液)。該液滴31滴下至第一螺桿搬送路11時,形成覆蓋通過該搬送路11之第一搬送螺桿23a、23b表面或缸壁27之內表面的液膜,因此熔融混合物容易滑移,結果容易生成前述樹脂塊30。In addition, although the gas lactide comes into contact with the observation window 19 and the like and is cooled and reliquefied (ie, refluxed), exhaust gas blockage occurs, but the exhaust chamber 3 configured as described above can effectively prevent the Problems due to reflux. That is, when a molten mixture containing polylactic acid, a depolymerization catalyst, and a carrier resin is introduced into the exhaust chamber 3 through the extruder 1 through the first screw conveying path 11 and gasification of lactide is continuously performed, sometimes Condensed droplets 31 (ie, reflux liquid) are generated on the side of the observation window 19. When the droplet 31 drops to the first screw conveying path 11, a liquid film covering the surface of the first conveying screws 23 a and 23 b or the inner surface of the cylinder wall 27 passing through the conveying path 11 is formed, so that the molten mixture is liable to slip and the result is easy. The aforementioned resin block 30 is generated.

然而,在如圖2所示之構造的排氣室3中傾斜地設有觀察窗19,且凝結之液滴31沿著觀察窗19流動落下,接著收容在藉由側壁13與第一螺桿搬送路11完全地區隔之收納槽21中。即,可有效地避免液滴31滴下至第一螺桿搬送路11內,促使樹脂塊30產生的問題。 此外,雖然液滴31落下至第一螺桿搬送路11造成乳酸交酯反複之氣化及液化,促進乳酸交酯之消旋化,因此使乳酸交酯之光學純度降低,但在如上所述之構造的排氣室3中亦可有效地避免如此之問題。However, an observation window 19 is provided obliquely in the exhaust chamber 3 structured as shown in FIG. 2, and the condensed droplets 31 flow down along the observation window 19, and are then accommodated in the conveyance path through the side wall 13 and the first screw. 11 In the storage compartment 21 completely separated. That is, it is possible to effectively avoid the problem that the liquid droplet 31 drips into the first screw conveyance path 11 and promotes the resin mass 30. In addition, although the drop 31 dropped to the first screw conveying path 11 caused repeated gasification and liquefaction of lactide, and promoted the racemization of lactide, thus reducing the optical purity of lactide, but as described above Such a problem can also be effectively avoided in the exhaust chamber 3 having a structure.

此外,上述觀察窗19宜如圖2所示地形成雙重窗,且藉由具有O環33a、33b之墊圈35安裝在頂壁17上。藉由如此之構造,可提高觀察窗19之保溫性而防止凝結,因此可有效地避免回流液之產生。In addition, the above-mentioned observation window 19 is preferably formed as a double window as shown in FIG. 2, and is mounted on the top wall 17 by a washer 35 having O-rings 33 a and 33 b. With such a structure, the heat-retaining property of the observation window 19 can be improved and condensation can be prevented, and thus the generation of reflux liquid can be effectively avoided.

另外,捕集上述液滴31(回流液)之收納槽21的底部設有回收貯存在收納槽21中之回流液31a的回收管線37,且其側壁之上部設有保持排氣室3之真空度或使用於破壞真空之真空破壞/回復管線39。藉由如此之構造,可回收貯存在收納槽21中之回流液31a。In addition, a recovery line 37 for recovering the reflux liquid 31a stored in the storage tank 21 is provided at the bottom of the storage tank 21 that collects the liquid droplets 31 (return liquid), and a vacuum holding the exhaust chamber 3 is provided above the sidewall. The vacuum destruction / recovery line 39 may be used to destroy the vacuum. With this structure, the reflux liquid 31a stored in the storage tank 21 can be recovered.

收納槽21之構造不限於圖2所示之構造,例如,收納槽21之底部透過捕集管線連結於暫時之捕集槽,且藉由在該暫時之捕集槽中設置真空破壞/回復管線及回收管線,可在不破壞排氣室3之真空系的情形下,透過捕集管線使貯存在收納槽21中之回流液31a移動至暫時之捕集槽中來回收。The structure of the storage tank 21 is not limited to the structure shown in FIG. 2. For example, the bottom of the storage tank 21 is connected to a temporary capture tank through a capture line, and a vacuum destruction / recovery line is provided in the temporary capture tank. And the recovery line, the return liquid 31a stored in the storage tank 21 can be moved to the temporary collection tank through the collection line without destroying the vacuum system of the exhaust chamber 3 and recovered.

此外,雖然藉由排氣室3氣化之乳酸交酯透過設於側壁13上部之捕集管15導入捕集裝置5,但如圖2所示地,該捕集管15朝上方傾斜地延伸且設有真空破壞防止閥50,因此製程運轉有異常時,可開閉該閥50。In addition, although the lactide vaporized by the exhaust chamber 3 is introduced into the trap device 5 through a trap tube 15 provided on the upper side of the side wall 13, the trap tube 15 extends obliquely upward as shown in FIG. 2 and The vacuum breakage prevention valve 50 is provided, so that the valve 50 can be opened and closed when there is an abnormality in the process operation.

另外,最好在該捕集管15之入口部分設有用以接受回流液之收納槽15a。即,宜形成在該收納槽15a中捕集在捕集管15內液化之回流液,使其不流動落下至螺桿搬送路11內的構造。此外,該收納槽15a中亦設有真空破壞/回復管線15b及回收管線15c。In addition, it is preferable that an inlet portion of the trap tube 15 is provided with a storage tank 15a for receiving a reflux liquid. That is, it is preferable to form the structure which collects the liquefied reflux liquid in the collection pipe 15 in this storage tank 15a, and makes it fall into the screw conveyance path 11 without flowing. In addition, the storage tank 15a is also provided with a vacuum destruction / recovery line 15b and a recovery line 15c.

由捕集管15導入捕集裝置5內且包含氣化之乳酸交酯的氣體混合物通過捕集裝置5內之氣液分離塔51及冷凝管線A,接著使乳酸交酯形成液體而由該氣體混合物回收。 在如此進行乳酸交酯之回收的本發明中,排氣室3內藉由真空泵7之真空抽吸保持0.1至8KPaA之壓力,藉此被加熱之乳酸交酯在排氣室3內氣化。接著,氣化乳酸交酯由捕集管15導入捕集裝置5內,並由冷凝管線A回收。例如,排氣室3內之壓力比上述範圍低時,因為真空度過高,所以形成許多樹脂塊而容易產生排氣堵塞。此外,排氣室3內之壓力比上述範圍高時,因為真空度過低,所以乳酸交酯之沸點下降不足且乳酸交酯氣化不足,有回收效率降低之傾向。另外,如此之回收作業必須極力抑制排氣室3內之壓力變動。具體而言,壓力變動宜抑制在±1KPaA內。該壓力變動過大時,熔融樹脂混合物中含有之乳酸交酯的沸點變化大,結果,容易產生排氣堵塞或成為回收效率降低之原因。The gas mixture containing the vaporized lactide introduced into the capture device 5 from the capture tube 15 passes through the gas-liquid separation tower 51 and the condensing line A in the capture device 5, and then the lactide is formed into a liquid and the gas is produced from the gas. The mixture was recovered. In the present invention in which the recovery of lactide is thus performed, the pressure in the exhaust chamber 3 is maintained at a pressure of 0.1 to 8 KPaA by the vacuum suction of the vacuum pump 7, whereby the heated lactide is vaporized in the exhaust chamber 3. Next, the vaporized lactide is introduced into the trap device 5 from the trap tube 15 and recovered through the condensation line A. For example, when the pressure in the exhaust chamber 3 is lower than the above-mentioned range, since the degree of vacuum is too high, a large number of resin blocks are formed, and exhaust blockage is likely to occur. In addition, when the pressure in the exhaust chamber 3 is higher than the above range, the degree of vacuum is too low, so the boiling point of lactide is not sufficiently lowered, and the lactide is not sufficiently vaporized, which tends to reduce the recovery efficiency. In addition, in such a recovery operation, it is necessary to suppress the pressure fluctuation in the exhaust chamber 3 as much as possible. Specifically, the pressure fluctuation should be suppressed within ± 1KPaA. When this pressure fluctuation is excessively large, the boiling point of the lactide contained in the molten resin mixture changes greatly, and as a result, exhaust gas clogging is likely to occur and the recovery efficiency may decrease.

在上述回收裝置中,連接於捕集管15之捕集裝置5,例如,如圖3所示地,具有氣液分離塔51,且該氣液分離塔51通入冷凝管線A,而冷凝管線A連接於真空泵7。即,包含由捕集管15流入之氣體狀乳酸交酯的氣體混合物通入氣液分離塔51,並藉由設於氣液分離塔51內之除霧器去除高分子量成分(例如,乳酸之寡聚物),接著,藉由在冷凝管線A之冷卻,回收液化氣體狀乳酸交酯及去除低分子量成分。即,包含由排氣室3捕集之乳酸交酯的氣體混合物中,除了乳酸交酯以外,亦含有來自乳酸之寡聚物、聚乳酸或混合於載體樹脂之聚合起始劑等的各種低分子量化合物等,因此必須去除該等低分子量化合物。具體而言,氣體回收之乳酸交酯通入氣液分離塔51並藉由氣液分離塔內之除霧器去除高分子量成分後,導入第一冷凝器71,只使乳酸交酯液化而形成液狀乳酸交酯來回收。 因此,為由排氣室3有效率地供給氣體狀混合物至氣液分離塔51及冷凝管線A,氣液分離塔51及冷凝管線A宜設置在比排氣室3高之位置。In the recovery device described above, the capture device 5 connected to the capture pipe 15 has, for example, a gas-liquid separation tower 51 as shown in FIG. 3, and the gas-liquid separation tower 51 is passed into the condensation line A, and the condensation line A is connected to the vacuum pump 7. That is, the gas mixture containing the gaseous lactide flowing in from the trap tube 15 is passed into a gas-liquid separation tower 51, and a high-molecular-weight component (for example, lactic acid) is removed by a mist eliminator provided in the gas-liquid separation tower 51. Oligomer), and then, by cooling in the condensing line A, liquefied gaseous lactide is recovered and low molecular weight components are removed. That is, the gas mixture containing the lactide trapped in the exhaust chamber 3 contains, in addition to lactide, various kinds of oligomers derived from lactic acid, polylactic acid, or a polymerization initiator mixed with a carrier resin. Molecular weight compounds, etc., these low molecular weight compounds must be removed. Specifically, the gas-recovered lactide passes through the gas-liquid separation tower 51 and is removed by a mist eliminator in the gas-liquid separation tower, and then is introduced into the first condenser 71 to liquefy only the lactide. The liquid lactide is recovered. Therefore, in order to efficiently supply the gaseous mixture from the exhaust chamber 3 to the gas-liquid separation tower 51 and the condensing line A, the gas-liquid separation tower 51 and the condensing line A should preferably be positioned higher than the exhaust chamber 3.

如由圖3可知地,冷凝管線A沿藉由真空泵7真空抽吸之氣體的流動方向,串聯地配置第一冷凝器71、第二冷凝器73及第三冷凝器75。即,第一冷凝器71藉由導入管線81連結於氣液分離塔51,且第二冷凝器73藉由連結管線83連結於第一冷凝器71,而第三冷凝器75藉由連結管線85連結於第二冷凝器73且藉由終結管線87連結於真空泵7。因此,包含由排氣室3排出之氣體狀乳酸交酯的氣體混合物通過氣液分離塔51,接著依序導入第一冷凝器71、第二冷凝器73及第三冷凝器75。As can be seen from FIG. 3, in the condensing line A, the first condenser 71, the second condenser 73, and the third condenser 75 are arranged in series along the flow direction of the gas sucked by the vacuum pump 7. That is, the first condenser 71 is connected to the gas-liquid separation column 51 through the introduction line 81, the second condenser 73 is connected to the first condenser 71 through the connection line 83, and the third condenser 75 is connected through the connection line 85 The second condenser 73 is connected to the vacuum pump 7 through a termination line 87. Therefore, the gas mixture containing the gaseous lactide discharged from the exhaust chamber 3 passes through the gas-liquid separation column 51 and is sequentially introduced into the first condenser 71, the second condenser 73, and the third condenser 75.

第一冷凝器71使乳酸交酯液狀化而由氣體混合物回收,且在該第一冷凝器71中之熱交換溫度依據真空抽吸之真空度範圍設定在適當之範圍內。一般而言,在0.1KPaA至8KPaA之真空度範圍內熱交換溫度宜為60℃至140℃,而在真空度範圍為0.5KPaA至4KPaA內熱交換溫度80℃至90℃更佳。熱交換溫度比上述範圍低時,產生低沸點不純物之液狀化,恐有回收乳酸交酯之純度下降之虞,而熱交換溫度比上述範圍高時,因為乳酸交酯難以液狀化,所以恐有乳酸交酯回收效率降低之虞。The first condenser 71 liquefied lactide and recovered it from the gas mixture, and the heat exchange temperature in the first condenser 71 was set within an appropriate range according to the range of vacuum degree of vacuum suction. Generally speaking, the heat exchange temperature in the vacuum range of 0.1KPaA to 8KPaA is preferably 60 ° C to 140 ° C, and the heat exchange temperature in the vacuum range of 0.5KPaA to 4KPaA is more preferably 80 ° C to 90 ° C. When the heat exchange temperature is lower than the above range, liquefaction of low boiling point impurities may occur, and the purity of the recovered lactide may decrease. When the heat exchange temperature is higher than the above range, the lactide is difficult to liquefy, so There is a fear that the recovery efficiency of lactide may decrease.

此外,第一冷凝器71,如圖3所示地,連結乳酸交酯容器89,且藉由第一冷凝器71中之冷卻而液化的乳酸交酯被捕集在容器89中,而剩餘之氣體通過連結管線83導入第二冷凝器73。In addition, as shown in FIG. 3, the first condenser 71 is connected to a lactide container 89, and the lactide liquefied by cooling in the first condenser 71 is trapped in the container 89, and the remaining The gas is introduced into the second condenser 73 through the connection line 83.

第二冷凝器73係使用於去除沸點比乳酸交酯低之低分子量化合物,因此,其熱交換溫度比第一冷凝器71低,且一般設定於大約40至-20℃。藉由在第二冷凝器73中之冷卻而液化之低分子量化合物被捕集在容器90中,接著排出或回收。此外,去除低分子量化合物且藉由第二冷凝器73冷卻之氣體透過連結管線85導入第三冷凝器75。The second condenser 73 is used to remove low-molecular-weight compounds having a lower boiling point than lactide. Therefore, the second condenser 73 has a lower heat exchange temperature than the first condenser 71 and is generally set at about 40 to -20 ° C. The low-molecular-weight compound liquefied by cooling in the second condenser 73 is trapped in the container 90 and then discharged or recovered. In addition, the low molecular weight compound is removed and the gas cooled by the second condenser 73 is introduced into the third condenser 75 through the connection line 85.

第三冷凝器75係使用於去除沸點更低之低分子量化合物(難凝集性成分)。因此,其熱交換溫度比第二冷凝器73低,且一般設定於-40至-60℃之極低溫,形成所謂深冷阱而使更低分子量之化合物液化並藉由第三冷凝器75內之除霧器等移除。此外,剩餘之氣體通過設於終結管線87中之過濾器93並藉由真空泵7抽吸而排出。The third condenser 75 is used to remove low-molecular-weight compounds (hard-aggregating components) having a lower boiling point. Therefore, its heat exchange temperature is lower than that of the second condenser 73, and it is generally set at an extremely low temperature of -40 to -60 ° C, forming a so-called cryogenic trap to liquefy compounds of lower molecular weight and passing through the third condenser 75 Remove the defogger, etc. In addition, the remaining gas passes through a filter 93 provided in the termination line 87 and is sucked out by the vacuum pump 7.

設於如上所述之冷凝管線A的第一至三冷凝器71、73、75只要熱交換溫度設定在上述範圍內,亦可具有本身習知之構造。例如,第一冷凝器71及第二冷凝器73可使用水(溫水)作為冷媒,且進行深冷阱之冷卻的第三冷凝器75可使用無水乙醇作為冷媒。The first to third condensers 71, 73, and 75 provided in the condensation line A as described above may have a structure known per se as long as the heat exchange temperature is set within the above range. For example, the first condenser 71 and the second condenser 73 may use water (warm water) as a refrigerant, and the third condenser 75 that performs cooling of the cryogenic trap may use anhydrous ethanol as a refrigerant.

如此,通過氣液分離塔51,將去除高分子量之寡聚物成分的氣體混合物導入冷凝管線A,接著,除了使氣體混合物中含有之氣體狀乳酸交酯液化而捕集的第一冷凝器71以外,藉由進一步使用去除低分子量之第二冷凝器73及第三冷凝器75,可有效地防止在該冷凝管線A中之低分子量化合物等的不純物累積及配管堵塞,因此亦可有效地防止如此不純物造成之真空泵7的動作不良。In this manner, the gas mixture from which the high molecular weight oligomer component is removed is introduced into the condensation line A through the gas-liquid separation column 51, and then the first condenser 71 is trapped in addition to liquefying the gaseous lactide contained in the gas mixture. In addition, by further using the second and third condensers 73 and 75 to remove the low molecular weight, impurities such as low molecular weight compounds in the condensation line A can be effectively prevented from being accumulated and piping clogging, so it can be effectively prevented. The impure operation of the vacuum pump 7 caused by such impurities.

此外,在上述圖3之例子中,雖然為去除沸點比乳酸交酯低之低分子量化合物,設有第二冷凝器73及第三冷凝器75,但本發明不限於該態樣。例如,亦可進一步在第二冷凝器73與第三冷凝器75之間設置熱交換溫度不同的冷卻器。此外,可依場合省略第三冷凝器75(或第二冷凝器73)。Further, in the example of FIG. 3 described above, the second condenser 73 and the third condenser 75 are provided to remove low molecular weight compounds having a boiling point lower than that of lactide, but the present invention is not limited to this aspect. For example, a cooler having a different heat exchange temperature may be further provided between the second condenser 73 and the third condenser 75. In addition, the third condenser 75 (or the second condenser 73) may be omitted as occasion demands.

此外,雖然在圖3中冷凝管線A形成單一串聯管線,且第一至三冷凝器71、73、75設在一條管線上,但在第一冷凝器71之導入管線81與由第三冷凝器75到真空泵7之終結管線87間,可設置分支之並聯管線,且在並聯之管線中分別設置冷凝器,亦可同時進行真空泵7之真空抽吸的乳酸交酯捕集作業及管線清洗作業。以下,進行真空抽吸之乳酸交酯捕集作業的管線稱為乳酸交酯捕集管線,且進行清洗作業之管線稱為真空抽吸清洗管線。In addition, although the condensing line A forms a single series line in FIG. 3, and the first to third condensers 71, 73, and 75 are provided on one line, the introduction line 81 of the first condenser 71 and the third condenser Between 75 and the end line 87 of the vacuum pump 7, a branched parallel line can be set, and a condenser is installed in the parallel line, and the vacuum pumping of the lactide collection operation and the line cleaning operation of the vacuum pump 7 can be performed at the same time. Hereinafter, the pipeline for vacuum lactide trapping operation is referred to as a lactide trapping line, and the pipeline for cleaning operation is referred to as a vacuum suction cleaning line.

例如,如圖4所示地,在該態樣中,在由第一冷凝器71延伸之連結管線83的中途設有三向閥等之切換閥M,且在該部分分支成並聯管線Xa、Xb。該等並聯管線Xa、Xb分別延伸到設於連接真空泵7之終結管線87的三向閥等的切換閥V。For example, as shown in FIG. 4, in this aspect, a switching valve M such as a three-way valve is provided in the middle of the connecting line 83 extending from the first condenser 71, and branched into parallel lines Xa, Xb at this portion. . The parallel lines Xa and Xb each extend to a switching valve V such as a three-way valve provided in the termination line 87 connected to the vacuum pump 7.

在此,其中一並聯管線Xa中依序配置第二冷凝器73a及第三冷凝器75a,且另一並聯管線Xb中依序配置第二冷凝器73b及第三冷凝器75b。 上述第二冷凝器73a、73b及第三冷凝器75a、75b分別相當於圖2中之第二冷凝器73、第三冷凝器75。Here, a second condenser 73a and a third condenser 75a are sequentially arranged in one of the parallel lines Xa, and a second condenser 73b and a third condenser 75b are sequentially arranged in the other parallel line Xb. The above-mentioned second condensers 73a and 73b and third condensers 75a and 75b correspond to the second condenser 73 and the third condenser 75 in FIG. 2, respectively.

如由圖4可知地,在由切換閥M分支之其中一並聯管線Xa中,由切換閥M延伸之連結管線83a中設有切換閥Ma,且該連結管線83a連接於第二冷凝器73a。此外,第二冷凝器73a藉由連結管線85a連接於第三冷凝器75a,且連接於切換閥V之終結管線87a由第三冷凝器75a延伸。該終結管線87a中設有切換閥Ma'。 同樣地,在另一並聯管線Xb中,由切換閥M延伸之連結管線83b中設有切換閥Mb,且該連結管線83b連接於第二冷凝器73b。此外,第二冷凝器73b藉由連結管線85b連接於第三冷凝器75b,且連接於切換閥V之終結管線87b由第三冷凝器75b延伸。該終結管線87b中設有切換閥Mb'。As can be seen from FIG. 4, in one of the parallel lines Xa branched from the switching valve M, a switching valve Ma is provided in the connecting line 83a extending from the switching valve M, and the connecting line 83a is connected to the second condenser 73a. In addition, the second condenser 73a is connected to the third condenser 75a through a connection line 85a, and a termination line 87a connected to the switching valve V is extended from the third condenser 75a. The termination line 87a is provided with a switching valve Ma '. Similarly, in another parallel line Xb, a switching valve Mb is provided in the connecting line 83b extending from the switching valve M, and the connecting line 83b is connected to the second condenser 73b. In addition, the second condenser 73b is connected to the third condenser 75b through a connecting line 85b, and a termination line 87b connected to the switching valve V is extended from the third condenser 75b. The termination line 87b is provided with a switching valve Mb '.

此外,並聯管線Xa中之切換閥Ma及並聯管線Xb中之切換閥Mb連接具有調壓閥95之清潔氣體導入管線101。 另外,並聯管線Xa中之切換閥Ma’及並聯管線Xb中之切換閥Mb’連結排氣管線109,該排氣管線109具有調壓閥103、真空腔室105及過濾器111且具有清潔用真空泵107。 設在如此之並聯管線Xa、Xb、清潔氣體導入管線101及排氣管線109中的各種閥均藉由未圖示之閥控制裝置進行其開閉,藉此,由第一冷凝器71排出之氣體混合物流入其中一並聯管線Xa,並藉由在第二冷凝器73a及第三冷凝器75a中之冷卻去除低分子量化合物時,加熱至例如室溫以上,最好是50℃以上之清潔氣體可流入另一並聯管線Xb,以進行配管等之清洗。In addition, the switching valve Ma in the parallel line Xa and the switching valve Mb in the parallel line Xb are connected to a clean gas introduction line 101 having a pressure regulating valve 95. In addition, the switching valve Ma 'in the parallel line Xa and the switching valve Mb' in the parallel line Xb are connected to an exhaust line 109, which has a pressure regulating valve 103, a vacuum chamber 105, and a filter 111 and is provided for cleaning. Vacuum pump 107. Various valves provided in such parallel lines Xa, Xb, clean gas introduction line 101, and exhaust line 109 are opened and closed by a valve control device (not shown), whereby the gas discharged from the first condenser 71 The mixture flows into one of the parallel lines Xa, and when the low molecular weight compounds are removed by cooling in the second condenser 73a and the third condenser 75a, the cleaning gas is heated to, for example, room temperature or higher, preferably 50 ° C or higher. The other line Xb is connected in parallel for cleaning of piping and the like.

例如,在圖4之例子中,切換閥M在並聯管線Xa側開啟(並聯管線Xb側關閉),且切換閥V控制成在並聯管線Xa側開啟之狀態(並聯管線Xb側關閉之狀態)。 此外,切換閥Ma之清潔氣體導入管線101側關閉,接著,切換閥Ma'之排氣管線109側關閉。因此,離開第一冷凝器71之氣體混合物由切換閥M通過第二冷凝器73a而去除低分子量化合物,接著,通過第三冷凝器75a而去除更低分子量化合物,並通過切換閥V後,通過過濾器93由真空泵7排氣。For example, in the example of FIG. 4, the switching valve M is opened on the parallel line Xa side (the parallel line Xb side is closed), and the switching valve V is controlled to be opened on the parallel line Xa side (the parallel line Xb side is closed). In addition, the clean gas introduction line 101 side of the switching valve Ma is closed, and then the exhaust line 109 side of the switching valve Ma 'is closed. Therefore, the gas mixture leaving the first condenser 71 is removed by the switching valve M through the second condenser 73a to remove the low molecular weight compounds, and then, the third condenser 75a is used to remove the lower molecular weight compounds, and after passing through the switching valve V, it passes The filter 93 is exhausted by the vacuum pump 7.

另一方面,在另一並聯管線Xb中,切換閥Mb之清潔氣體導入管線101側開啟,接著,切換閥Mb'之排氣管線109側呈開啟狀態後,清潔氣體導入管線101內之調壓閥95呈開啟狀態,且排氣管線109內之調壓閥103亦調整成開啟狀態。 因此,在該狀態下使清潔用真空泵107作動時,清潔氣體由預定氣體源通過清潔氣體導入管線101,流入並聯管線Xb內,接著由連結管線83b、第二冷凝器73b、連結管線85b、第三冷凝器75b、終結管線87b通過閥Mb'流入排氣管線109後,依序通過真空腔室105、過濾器111,由清潔用真空泵107排出。On the other hand, in another parallel line Xb, the clean gas introduction line 101 side of the switching valve Mb is opened, and then, after the exhaust line 109 side of the switching valve Mb ′ is opened, the pressure in the clean gas introduction line 101 is adjusted. The valve 95 is in an open state, and the pressure regulating valve 103 in the exhaust line 109 is also adjusted to an open state. Therefore, when the cleaning vacuum pump 107 is operated in this state, the cleaning gas is introduced into the parallel line Xb from the predetermined gas source through the cleaning gas introduction line 101, and then the connection line 83b, the second condenser 73b, the connection line 85b, the first After the three condensers 75b and the termination line 87b flow into the exhaust line 109 through the valve Mb ', they sequentially pass through the vacuum chamber 105 and the filter 111, and are discharged by the cleaning vacuum pump 107.

即,並聯管線Xa連接於真空泵7且成為進行真空抽吸之乳酸交酯捕集作業的乳酸交酯捕集管線,並對通過第一冷凝器71之氣體藉由第二冷凝器73a及第三冷凝器75a去除低分子量化合物。另一方面,並聯管線Xb透過清潔氣體導入管線101連接於清潔用真空泵107且成為進行清洗作業之真空抽吸清洗管線,並在不使Xa側管線之真空度變動的情形下,藉由清潔氣體清洗Xb側管線之各種配管及冷凝器。That is, the parallel line Xa is connected to the vacuum pump 7 and serves as a lactide trap line for performing a vacuum lactide trap operation. The gas passing through the first condenser 71 is passed through the second condenser 73a and the third The condenser 75a removes low molecular weight compounds. On the other hand, the parallel line Xb is connected to the cleaning vacuum pump 107 through the cleaning gas introduction line 101 and becomes a vacuum suction and cleaning line for performing cleaning operations. Without changing the vacuum degree of the Xa side line, the cleaning gas is used. Clean various piping and condenser of Xb side pipeline.

此外,進行並聯管線Xa側之清洗時,進行與上述完全相反之操作。 即,如圖5所示地,切換閥M在並聯管線Xb側開啟(並聯管線Xa側關閉),且切換閥V控制成在並聯管線Xb側開啟之狀態(並聯管線Xa側關閉之狀態)。 另外,切換閥Mb之清潔氣體導入管線101側關閉,接著,切換閥Mb'之排氣管線109側關閉。因此,離開第一冷凝器71之氣體混合物由切換閥M通過第二冷凝器73b而去除低分子量化合物,接著,通過第三冷凝器75b而去除更低分子量化合物,並通過切換閥V後,通過過濾器93由真空泵7排氣。In addition, when performing cleaning on the parallel line Xa side, an operation completely opposite to the above is performed. That is, as shown in FIG. 5, the switching valve M is opened on the parallel line Xb side (the parallel line Xa side is closed), and the switching valve V is controlled to be opened on the parallel line Xb side (the parallel line Xa side is closed). In addition, the clean gas introduction line 101 side of the switching valve Mb is closed, and then, the exhaust line 109 side of the switching valve Mb ′ is closed. Therefore, the gas mixture leaving the first condenser 71 is removed by the switching valve M through the second condenser 73b to remove low molecular weight compounds, and then the third condenser 75b is used to remove lower molecular weight compounds, and after passing through the switching valve V, it passes The filter 93 is exhausted by the vacuum pump 7.

另一方面,在另一並聯管線Xa中,切換閥Ma之清潔氣體導入管線101側開啟,接著,切換閥Ma'之排氣管線109側呈開啟狀態後,清潔氣體導入管線101內之調壓閥95呈開啟狀態,且排氣管線109內之調壓閥103亦調整成開啟狀態。 因此,在該狀態下使清潔用真空泵107作動時,清潔氣體由預定氣體源通過清潔氣體導入管線101,流入並聯管線Xa內,接著由連結管線83a、第二冷凝器73a、連結管線85a、第三冷凝器75a、終結管線87a通過閥Ma'流入排氣管線109後,依序通過真空腔室105、過濾器111,由清潔用真空泵107排出。On the other hand, in another parallel line Xa, the clean gas introduction line 101 side of the switching valve Ma is opened, and then, after the exhaust line 109 side of the switching valve Ma ′ is opened, the pressure in the clean gas introduction line 101 is adjusted. The valve 95 is in an open state, and the pressure regulating valve 103 in the exhaust line 109 is also adjusted to an open state. Therefore, when the cleaning vacuum pump 107 is operated in this state, the cleaning gas flows into the parallel line Xa from the predetermined gas source through the cleaning gas introduction line 101, and then the connection line 83a, the second condenser 73a, the connection line 85a, the first After the three condensers 75a and the termination line 87a flow into the exhaust line 109 through the valve Ma ', they sequentially pass through the vacuum chamber 105 and the filter 111, and are discharged by the cleaning vacuum pump 107.

即,在並聯管線Xb側,對通過第一冷凝器71之氣體藉由第二冷凝器73b及第三冷凝器75b去除低分子量化合物,同時在另一並聯管線Xa側,藉由清潔氣體清洗各種配管及冷凝器。That is, on the parallel line Xb side, low-molecular-weight compounds are removed from the gas passing through the first condenser 71 by the second condenser 73b and the third condenser 75b, and at the same time, on the other parallel line Xa side, various kinds of gas are cleaned by clean gas Piping and condenser.

如此,在設置並聯管線之態樣中,可在不停止捕集裝置5之製程運轉的情形下進行清洗,因此可長時間連續地回收乳酸交酯,在工業上極有利。In this way, in the case where the parallel pipeline is installed, cleaning can be performed without stopping the process operation of the trapping device 5, so that the lactide can be continuously recovered for a long time, which is extremely industrially advantageous.

此外,在上述圖4及圖5中,雖然在連接於第一冷凝器71之連結管線83中設置切換閥M而形成並聯管線Xa、Xb,但亦可在連接氣液分離塔51及第一冷凝器71之導入管線81中設置切換閥M而形成並聯管線。此外,亦可在連接第二冷凝器73及第三冷凝器75之連結管線85中設置切換閥M而形成並聯管線。但是,使第一至三冷凝器71、73、75作動以回收乳酸交酯及去除低分子量化合物時,最容易在配管內產生不純物附著、堆積的是第一冷凝器71之下游側區域。因此,最好如圖4及圖5所示地,在連接於第一冷凝器71之連結管線83中設置切換閥M而形成並聯管線Xa、Xb。In addition, in FIGS. 4 and 5 described above, although the switching valve M is provided in the connecting line 83 connected to the first condenser 71 to form parallel lines Xa and Xb, the gas-liquid separation tower 51 and the first A switching valve M is provided in the introduction line 81 of the condenser 71 to form a parallel line. In addition, a switching valve M may be provided in the connecting line 85 connecting the second condenser 73 and the third condenser 75 to form a parallel line. However, when the first to third condensers 71, 73, and 75 are operated to recover lactide and remove low-molecular-weight compounds, it is most likely that impurities are attached to and accumulated in the piping are in the downstream region of the first condenser 71. Therefore, as shown in FIGS. 4 and 5, it is preferable to provide a switching valve M in the connecting line 83 connected to the first condenser 71 to form parallel lines Xa and Xb.

1‧‧‧擠出機1‧‧‧ Extruder

3‧‧‧排氣室3‧‧‧ exhaust chamber

4‧‧‧載體樹脂回收室4‧‧‧ Carrier resin recovery room

5‧‧‧捕集裝置5‧‧‧trapping device

6‧‧‧載體樹脂排出用擠出機6‧‧‧ Extruder for discharging carrier resin

7‧‧‧真空泵7‧‧‧vacuum pump

11‧‧‧第一螺桿搬送路11‧‧‧The first screw conveying road

13‧‧‧側壁13‧‧‧ sidewall

15‧‧‧捕集管15‧‧‧ collection tube

15a‧‧‧收納槽15a‧‧‧Storage slot

15b‧‧‧真空破壞/回復管線15b‧‧‧Vacuum destruction / recovery pipeline

15c‧‧‧回收管線15c‧‧‧Recovery pipeline

17‧‧‧頂壁17‧‧‧ top wall

19‧‧‧觀察窗19‧‧‧observation window

21‧‧‧收納槽21‧‧‧Storage trough

23a‧‧‧第一搬送螺桿23a‧‧‧The first conveying screw

23b‧‧‧第一搬送螺桿23b‧‧‧The first conveying screw

25‧‧‧落回螺桿25‧‧‧fall back to the screw

27‧‧‧缸壁27‧‧‧cylinder wall

30‧‧‧樹脂塊30‧‧‧resin block

31‧‧‧液滴31‧‧‧ droplet

31a‧‧‧回流液31a‧‧‧reflux

33a‧‧‧O環33a‧‧‧O ring

33b‧‧‧O環33b‧‧‧O ring

35‧‧‧墊圈35‧‧‧washer

37‧‧‧回收管線37‧‧‧ Recovery pipeline

39‧‧‧真空破壞/回復管線39‧‧‧Vacuum destruction / recovery pipeline

50‧‧‧真空破壞防止閥50‧‧‧Vacuum damage prevention valve

51‧‧‧氣液分離塔51‧‧‧Gas-liquid separation tower

60‧‧‧第二螺桿搬送路60‧‧‧Second screw conveying path

71‧‧‧第一冷凝器71‧‧‧first condenser

73‧‧‧第二冷凝器73‧‧‧Second condenser

73a‧‧‧第二冷凝器73a‧‧‧Second condenser

73b‧‧‧第二冷凝器73b‧‧‧Second condenser

75‧‧‧第三冷凝器75‧‧‧Third condenser

75a‧‧‧第三冷凝器75a‧‧‧Third condenser

75b‧‧‧第三冷凝器75b‧‧‧third condenser

81‧‧‧導入管線81‧‧‧ import pipeline

83‧‧‧連結管線83‧‧‧ Connected pipeline

83a‧‧‧連結管線83a‧‧‧connected pipeline

83b‧‧‧連結管線83b‧‧‧connected pipeline

85‧‧‧連結管線85‧‧‧ Connected pipeline

85a‧‧‧連結管線85a‧‧‧connected pipeline

85b‧‧‧連結管線85b‧‧‧connected pipeline

87‧‧‧終結管線87‧‧‧Ending the pipeline

87a‧‧‧終結管線87a‧‧‧End pipeline

87b‧‧‧終結管線87b‧‧‧End pipeline

89‧‧‧乳酸交酯容器89‧‧‧lactide container

90‧‧‧容器90‧‧‧ container

93‧‧‧過濾器93‧‧‧Filter

95‧‧‧調壓閥95‧‧‧ pressure regulating valve

101‧‧‧清潔氣體導入管線101‧‧‧clean gas introduction pipeline

103‧‧‧調壓閥103‧‧‧ pressure regulating valve

105‧‧‧真空腔室105‧‧‧vacuum chamber

107‧‧‧清潔用真空泵107‧‧‧Vacuum pump for cleaning

109‧‧‧排氣管線109‧‧‧Exhaust line

111‧‧‧過濾器111‧‧‧ Filter

A‧‧‧冷凝管線A‧‧‧Condensing pipeline

M‧‧‧切換閥M‧‧‧ switching valve

Ma‧‧‧切換閥Ma‧‧‧Switching valve

Ma'‧‧‧切換閥Ma'‧‧‧ switching valve

Mb‧‧‧切換閥Mb‧‧‧ switching valve

Mb'‧‧‧切換閥Mb'‧‧‧ switching valve

V‧‧‧切換閥V‧‧‧ switching valve

Xa‧‧‧並聯管線Xa‧‧‧ Parallel Pipeline

Xb‧‧‧並聯管線Xb‧‧‧ Parallel Pipeline

圖1係顯示使用於較佳地實施本發明之回收方法的回收裝置的概略構造圖。 圖2係顯示圖1之回收裝置的排氣室的截面構造圖。 圖3係顯示圖1之回收裝置的捕集裝置的最簡單態樣圖。 圖4係顯示圖1之回收裝置的捕集裝置中之冷凝管線例的圖,且係顯示使該冷凝管線中之並聯管線中的一並聯管線動作來進行乳酸交酯之回收的狀態圖。 圖5係顯示圖1之回收裝置的捕集裝置中之冷凝管線例的圖,且係顯示使該冷凝管線中之並聯管線中的另一並聯管線動作來進行乳酸交酯之回收的狀態圖。FIG. 1 is a schematic configuration diagram of a recovery device used to implement the recovery method of the present invention. FIG. 2 is a sectional structural view showing an exhaust chamber of the recovery device of FIG. 1. FIG. FIG. 3 is a diagram showing the simplest aspect of the capture device of the recovery device of FIG. 1. FIG. FIG. 4 is a diagram showing an example of a condensing line in the capture device of the recovery device of FIG. 1, and is a diagram showing a state in which a parallel line in the parallel line in the condensing line is operated to recover lactide. FIG. 5 is a diagram showing an example of a condensing line in the capture device of the recovery device of FIG. 1, and is a diagram showing a state in which another parallel line in the parallel line in the condensing line is operated to recover lactide.

Claims (9)

一種乳酸交酯回收方法,該方法係在減壓下保持包含乳酸交酯之樹脂混合物,並使該樹脂混合物中含有之乳酸交酯氣化,接著一面真空抽吸包含氣體狀乳酸交酯之氣體混合物,一面導入冷凝管線而回收乳酸交酯,其特徵為: 該冷凝管線以冷卻溫度依序降低之方式串聯地排列多數冷凝器,且藉由該等冷凝器由該氣體混合物捕集乳酸交酯並分離乳酸交酯以外之不純物。A method for recovering lactide, the method is to maintain a resin mixture containing lactide under reduced pressure, and gasify the lactide contained in the resin mixture, and then vacuum suction the gas containing gaseous lactide The mixture is introduced into a condensing line to recover lactide, which is characterized in that: the condensing line arranges a plurality of condensers in series so that the cooling temperature decreases sequentially, and the lactide is captured by the gas mixture through the condensers And the impurities other than lactide are separated. 如申請專利範圍第1項之乳酸交酯回收方法,其中該乳酸交酯係藉由聚乳酸之解聚合產生。For example, the method for recovering lactide in item 1 of the patent application range, wherein the lactide is produced by depolymerization of polylactic acid. 如申請專利範圍第2項之乳酸交酯回收方法,其中使該氣體混合物通過用以去除乳酸寡聚物成分之氣液分離塔,並連續地導入該冷凝管線。For example, the method for recovering lactide in item 2 of the patent application range, wherein the gas mixture is passed through a gas-liquid separation tower for removing lactic acid oligomer components, and is continuously introduced into the condensation line. 如申請專利範圍第1項之乳酸交酯回收方法,其中依序配置第一冷凝器、第二冷凝器及第三冷凝器作為該多數冷凝器。For example, the method for recovering lactide in the first item of the patent scope, wherein the first condenser, the second condenser, and the third condenser are sequentially arranged as the majority condenser. 如申請專利範圍第1項之乳酸交酯回收方法,其中在0.1至8kPaA之真空度範圍內真空抽吸該氣體混合物。For example, the method for recovering lactide in item 1 of the patent application range, wherein the gas mixture is vacuum-sucked in a vacuum range of 0.1 to 8 kPaA. 如申請專利範圍第4項之乳酸交酯回收方法,其中將在該第一冷凝器之熱交換溫度設定在60至140℃。For example, the method for recovering lactide in item 4 of the patent application range, wherein the heat exchange temperature in the first condenser is set to 60 to 140 ° C. 如申請專利範圍第1項之乳酸交酯回收方法,其中該冷凝管線包含:用以將該氣體混合物導入該冷凝管線之導入管線;及連接於用以真空抽吸之真空泵的終結管線,且更具有在該導入管線與該終結管線之間透過切換閥分支的並聯管線,而該並聯管線中以分別至少包含位於最下游側之冷凝器的方式設有至少1個冷凝器, 真空抽吸清洗管線透過切換閥連結於該並聯管線之各分支的流路。For example, the method for recovering lactide in item 1 of the patent scope, wherein the condensation line includes: an introduction line for introducing the gas mixture into the condensation line; and a termination line connected to a vacuum pump for vacuum suction, and more There is a parallel pipeline branched through a switching valve between the introduction pipeline and the termination pipeline, and at least one condenser is provided in the parallel pipeline so as to include at least the condenser located at the most downstream side, and the vacuum suction cleaning pipeline A flow path of each branch of the parallel pipeline is connected through a switching valve. 如申請專利範圍第7項之乳酸交酯回收方法,其中,使該氣體混合物流入該並聯管線之分支中的一流路來進行乳酸交酯之回收,同時使連接於該並聯管線之分支中的另一流路的該真空抽吸清洗管線動作來進行真空清洗。For example, the method for recovering lactide in item 7 of the scope of the patent application, wherein the gas mixture is allowed to flow into the first-stage path in the branch of the parallel pipeline for recovery of lactide, and at the same time, another one connected to the branch of the parallel pipeline The vacuum suction cleaning line of the first flow path operates to perform vacuum cleaning. 如申請專利範圍第7項之乳酸交酯回收方法,其中在該導入管線中配置第一冷凝器,且在該並聯管線之各分支的流路中分別配置剩餘之冷凝器。For example, the method for recovering lactide in item 7 of the scope of patent application, wherein a first condenser is arranged in the introduction pipeline, and the remaining condensers are arranged in the flow paths of the branches of the parallel pipeline.
TW106136818A 2016-11-09 2017-10-26 Method of recovering lactide TWI742185B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2016219186A JP6848362B2 (en) 2016-11-09 2016-11-09 Lactide recovery method
JP2016-219186 2016-11-09

Publications (2)

Publication Number Publication Date
TW201827502A true TW201827502A (en) 2018-08-01
TWI742185B TWI742185B (en) 2021-10-11

Family

ID=62110154

Family Applications (1)

Application Number Title Priority Date Filing Date
TW106136818A TWI742185B (en) 2016-11-09 2017-10-26 Method of recovering lactide

Country Status (3)

Country Link
JP (1) JP6848362B2 (en)
TW (1) TWI742185B (en)
WO (1) WO2018088182A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20220013201A (en) * 2020-07-24 2022-02-04 주식회사 엘지화학 Apparatus for preparing oligomer

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2822906B2 (en) * 1995-02-06 1998-11-11 株式会社島津製作所 Method and apparatus for producing lactide
JP3503127B2 (en) * 1995-09-14 2004-03-02 トヨタ自動車株式会社 Method for recovering lactide from high molecular weight polylactic acid
JPH107773A (en) * 1996-06-21 1998-01-13 Dainippon Ink & Chem Inc Method for recovering residual monomer
JP3330284B2 (en) * 1996-07-03 2002-09-30 株式会社神戸製鋼所 Method for producing polylactic acid
JPH10306091A (en) * 1997-05-08 1998-11-17 Shimadzu Corp Production of lactide
JPH1135579A (en) * 1997-07-17 1999-02-09 Shimadzu Corp Production of lactide in organic solvent
JP2006241022A (en) * 2005-03-01 2006-09-14 Hitachi Ltd Apparatus for producing lactide and method for producing the lactide
JP4696824B2 (en) * 2005-10-07 2011-06-08 株式会社日立プラントテクノロジー Polyester production method and polyester production apparatus
JP4427571B2 (en) * 2007-11-07 2010-03-10 株式会社日立プラントテクノロジー Apparatus and method for polymer synthesis
JP5459974B2 (en) * 2008-04-11 2014-04-02 株式会社日立製作所 Method and apparatus for producing purified lactic acid cyclic dimer, and method and apparatus for producing polylactic acid
WO2010105143A2 (en) * 2009-03-13 2010-09-16 Natureworks Llc Methods for producing lactide with recycle of meso-lactide
JP6206514B2 (en) * 2016-01-19 2017-10-04 東洋製罐株式会社 How to recover lactide
JP6206474B2 (en) * 2015-12-09 2017-10-04 東洋製罐株式会社 Lactide recovery method
JP6691656B2 (en) * 2016-01-29 2020-05-13 東洋製罐株式会社 Lactide recovery method

Also Published As

Publication number Publication date
JP6848362B2 (en) 2021-03-24
JP2018076257A (en) 2018-05-17
WO2018088182A1 (en) 2018-05-17
TWI742185B (en) 2021-10-11

Similar Documents

Publication Publication Date Title
TWI747867B (en) Method of recovering lactide
TWI481443B (en) Condensation and washing device, polymerisation device and also method for cleaning process vaporrs during the production of polylactide
EA028421B1 (en) Device and method for removing a cyclic diester from polymer melts
JP7238416B2 (en) Lactide recovery method
TWI742185B (en) Method of recovering lactide
JP5077170B2 (en) Process for producing polyhydroxycarboxylic acid
WO2008102896A1 (en) Method for separation/removal of foreign material from polyester fiber waste
JP6206514B2 (en) How to recover lactide
JP6206474B2 (en) Lactide recovery method
US20090173618A1 (en) Method of an apparatus for generating a vacuum and for separating volatile compounds in polycondensation reactions
TWI739777B (en) Method of recovering lactide
KR101350346B1 (en) Polymerization reaction apparatus for polyester
US20220297026A1 (en) Clog free condensation system for pyrolysis vapor of pet containing polymer
JP2006056957A (en) Apparatus for converting waste plastic into oil
CN218485911U (en) Vacuum device in PBAT production process
CN114712885A (en) Polycarbonate solution processing apparatus and polycarbonate waste recycling dichloromethane device
CN212610381U (en) High-efficient polyester polycondensation reaction system
JPH1045888A (en) Wet type condenser
CN102585284A (en) Method for recovering solvent from oligomer