WO2005026245A1

WO2005026245A1 - Method of continuously depolymerizing polyester, polycarbonate, or polylactic acid with supercritical fluid and apparatus for continuous depolymerization

Info

Publication number: WO2005026245A1
Application number: PCT/JP2004/013098
Authority: WO
Inventors: Shuichi Matsumura; Yasushi Osanai
Original assignee: Keio University
Priority date: 2003-09-09
Filing date: 2004-09-09
Publication date: 2005-03-24
Also published as: JP2005082710A

Abstract

A method of the continuous depolymerization of a polyester, polycarbonate, or polylactic acid which comprises continuously passing both a supercritical fluid and an organic solvent solution of the polyester, polycarbonate, or polylactic acid through a column packed with a hydrolase to depolymerize the polyester, polycarbonate, or polylactic acid by the action of the hydrolase and separating a depolymerization product from the reaction mixture which contains the depolymerization product and flows out from the hydrolase-packed column; and an apparatus for continuous depolymerization for use in the continuous depolymerization method, which comprises a device for producing a supercritical fluid, a column packed with a hydrolase, a back pressure regulator, a means for separating a depolymerization product from a reaction mixture containing the depolymerization product, a means for sending the supercritical fluid produced by the device for supercritical-fluid production to the column, and a means for sending an organic solvent solution of a polyester, polycarbonate, or polylactic acid to the column.

Description

Specification

Continuous depolymerization method of polyester, polycarbonate or polylactic acid using supercritical fluid, and continuous depolymerization apparatus

Technical field

The present invention relates to a method for continuously depolymerizing polyester, polycarbonate or polylactic acid using a supercritical fluid.

Background art

[0002] One of the important issues in science and technology in the 21st century is "construction of green chemistry"

. In particular, synthetic polymers are produced around 150 million tons of petroleum and natural gas resources annually around the world, and are chemically synthesized. In order for this field to achieve sustainable development in the future, energy conservation is essential. Development of chemical recycling technology for molds has been requested.

The material recycling method, the chemical recycling method, the thermal recycling method, etc. are used to recycle synthetic polymers, but the ability to effectively use carbon resources must ultimately be returned to raw materials by the chemical recycling method. Is ideal. This chemical recycling method is known to recover monomers by a chemical depolymerization reaction. It is a large energy and energy consuming type, has a large burden on the environment, and is generally not profitable.

[0003] An energy-saving chemical recycling technology is urgently required for such an energy-intensive chemical recycling technology. In response to this request, the present inventors have proposed a chemical recycling technology using an enzyme catalyst. Was suggested. For example, Patent Literature 1 below describes a method for converting polyproprolataton into a cyclic dimer using an enzyme catalyst and a method for repolymerizing the generated cyclic dimer using an enzyme catalyst. Patent Document 2 describes the selective conversion of polytrimethylene carbonate (PTMC) to cyclic trimethylene carbonate (TMC) and a method for repolymerizing this cyclic TMC with an enzyme. A method for depolymerizing an alkylene alkanoate or poly (3-hydroxyalkanoate) into an oligomer having a cyclic body as a main component and a method for repolymerizing the cyclic oligomer are disclosed. In each of these methods, an oligomer having a cyclic body as a main component is formed by depolymerization of a polymer by an enzyme, and the oligomer is It is easily re-polymerized by an enzyme (and also by a diversion catalyst), and since the polymerization at that time is a ring-opening polymerization, there is no elimination component such as water and it is not necessary to take these out of the reaction system. It has the advantages that the polymerization reaction operation is simple, no exhaust equipment is required, and simultaneous molding is possible.

Further, the present inventors depolymerize polyester and polycarbonate in a supercritical fluid in the presence of an enzyme catalyst to obtain a repolymerizable oligomer having a cyclic body as a main component. A method for repolymerization in a fluid was proposed (see Patent Document 4 below). This method has the advantage that the burden on the environment and the human body is small without using a usual organic solvent, and that the reaction product can be easily separated from the system.

[0004] However, if depolymerization and repolymerization in a supercritical liquid are performed in a batch operation, the efficiency is low, and it is not sufficient as a chemical recycling technology for a large amount of consumed plastic.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-17385

Patent Document 2: JP 2002-17384 A

Patent Document 3: JP-A-2002-320499

Patent Document 4: Japanese Patent Application Laid-Open No. 2003-79388

Disclosure of the invention

Problems to be solved by the invention

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to continuously depolymerize polyester, polycarbonate, or polylactic acid in a supercritical fluid, thereby improving the efficiency. It is often to obtain a depolymerized product.

Means for solving the problem

[0006] In the method for continuously depolymerizing polyester, polycarbonate or polylactic acid of the present invention, both a supercritical fluid and an organic solvent solution of polyester, polycarbonate or polylactic acid are continuously passed through a column packed with a carohydrolysis enzyme, This is a method in which polyester, polycarbonate or polylactic acid is depolymerized by a hydrolase, and the depolymerized product is separated from the reaction mixture containing the depolymerized product flowing out of the column packed with the hydrolase. The supercritical fluid is preferably supercritical carbon dioxide, and the hydrolase is an immobilized enzyme. Is preferred.

The continuous depolymerization apparatus for use in the continuous depolymerization method of the present invention includes a supercritical fluid generator, a column packed with a hydrolytic enzyme, a knock pressure regulator, and a depolymerization product from a reaction mixture containing a depolymerization product. Means for separating a substance, means for sending a supercritical fluid produced by a supercritical fluid generating device to the column, and means for sending an organic solvent solution of polyester, polycarbonate or polylactic acid to the column. It is characterized by having. It is preferable that the continuous depolymerization apparatus further includes means for returning a gasified substance from the supercritical fluid discharged from the knock pressure regulator to the supercritical fluid generation apparatus.

The invention's effect

In the continuous depolymerization method of the present invention, since the raw material polymer is continuously passed through the column filled with the hydrolase, the depolymerization efficiency is dramatically increased as compared with the batch operation. In addition, since the continuous depolymerization method of the present invention uses a supercritical fluid as a solvent, it is more reactive (low-temperature reaction) than a method in which a solution in which a raw material polymer is dissolved only in an organic solvent is continuously passed through an enzyme-packed column. The cyclic oligomer obtained by the depolymerization method of the present invention can be easily repolymerized. On the other hand, when depolymerization is performed by chemical decomposition or thermal decomposition, both ends of the resulting low molecular weight compound are irregular, and it is impossible to repolymerize this to form a polymer. Further, when the cyclic oligomer is repolymerized, there is an advantage that there is no elimination product.

Further, since the enzyme in the column used in the present invention is stable for a long period (several months) and does not deteriorate, the same column can be used continuously for a long period, and a large amount of processing can be performed with high efficiency. It becomes possible.

In particular, by using supercritical carbon dioxide as the supercritical fluid and substituting most of the solvent used for depolymerization with supercritical carbon dioxide, the use of environmentally harmful organic solvents can be significantly reduced. (Ordinarily, polymers have low solubility in organic solvents such as toluene, so a large amount of organic solvent is necessary to dissolve them.) Therefore, the cost for regenerating the solvent can be reduced, and there is a danger of ignition, explosion, or ignition. Can be reduced. Using The carbon dioxide is not dangerous even if it is released into the atmosphere, and its recycling is easy. Brief Description of Drawings

FIG. 1 is a graph showing the results of MALDI-TOF MS analysis of the depolymerized product in Example 1.

FIG. 2 is a graph showing a ¹ H NMR analysis result of a depolymerized product in Example 1.

FIG. 3 is a graph showing changes in SEC analysis before and after depolymerization in Example 1.

[FIGS. 4 (A) and (B)] Analysis of hexamer in Example 1. FIG. 4 (A) shows the result of ¹ H NMR structural analysis, and FIG. 4 (B) shows MALDI-TOF MS analysis. The results are shown.

FIG. 5 is a graph showing changes in SEC analysis before and after depolymerization in Example 3.

FIG. 6 is a graph showing changes in SEC analysis before and after depolymerization in Example 4.

FIG. 7 is a graph showing changes in SEC analysis before and after depolymerization in Example 5.

FIG. 8 is a graph showing SEC analysis after the reaction of Comparative Example 1.

FIG. 9 is a conceptual diagram showing an example of a continuous depolymerization apparatus of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0009] In the continuous depolymerization method of the present invention, a supercritical fluid and an organic solvent solution of polyester, polycarbonate or polylactic acid are both continuously passed through a column packed with a hydrolase, and polyester, polycarbonate or It is characterized by depolymerizing polylactic acid and separating the depolymerized product from the reaction mixture containing the depolymerized product flowing out of the column packed with the hydrolase.

Examples of the polyester that can be used in the continuous depolymerization of the present invention include a polyester of polycarboxylic acid and a polyol, a hydroxycarboxylic acid or a polyester or polylatatatone having an intramolecular ester (latataton) force. Examples of the polyester comprising a polycarboxylic acid and a polyol include a repeating unit represented by the following structural formula (1) such as polybutylene succinate, polybutylene adipate, and poly (butylene succinate adipate) copolymer. Preferred are those having. [0010] [Formula 1]

Structural formula (1)

In the structural formula (1), Α represents a linear or branched alkylene group having 2 to 8 carbon atoms, and B represents a linear or branched alkylene group having 2 to 6 carbon atoms. . A and B may each be two or more different (ie, copolymers). Further, 50 mol% or less of the dicarboxylic acid represented by A (COOH) is converted to an aromatic dicarboxylic acid such as terephthalic acid.

2

It may be substituted with sulfonic acid, phthalic acid, isophthalic acid or the like.

As the polyester of the present invention, repeating units other than those represented by the structural formula (1), for example, repeating units represented by the following structural formulas (2) and Z or (3) (where D is a carbon atom 2-6 linear or branched alkylene, alkylene or alkylene group) of not more than 50 mol%.

[0012] [Formula 2]

0 0

II II

-C— CH = CH— C-1 0 ~ D- Structural formula (2)

Structural formula (3)

[0013] The molecular weight (number average molecular weight) of the polyester is not particularly limited, and the terminal group of the polyester can be substituted with any substituent determined by a polymer synthesis method.

[0014] Further, as the polyester or polylatatone from the hydroxycarboxylic acid, in addition to a hydroxycarboxylic acid or ratatone polymer having 3 to 20 carbon atoms, the polyester or polylatatatone has at least one kind of a repeating unit represented by the following structural formula (4). Also included are polyester or poly rataton. In the formula, R represents a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms.

[0015] [Formula 3]

Structural formula (4)

[0016] R may be two or more different types (copolymers) selected from a hydrogen atom and an alkyl group having 11 to 12 carbon atoms. R force S methyl group is poly (3-hydroxybutyric acid), R force methyl group and hydrogen atom is 3-hydroxybutyric acid Z 3-hydroxypropionic acid copolymer (PHBZPHP), R force methyl group And in the case of an ethyl group, it is 3-hydroxybutyric acid Z3-hydroxyvaleric acid copolymer (PHBZPHV). These are known as polymers produced by microorganisms. The terminal group of the polylatatatone can be substituted with a different substituent as determined by a polymer synthesis method. Further, the polylatatatone may further have one or more types of repeating units represented by the following structural formulas (5) to (7) in the molecule.

[0017] [Formula 4]

Structural formula

( Five )

Structural formula (6)

Structural formula (7)

[0018] In the formula, R is a linear or branched alkylene group having 117 carbon atoms, and R is 2-11 carbon atoms.

1 2 linear or branched alkylene group, R is 1 carbon

310 represents a straight-chain or branched alkylene group, and R represents a straight-chain or branched alkylene group having 2 to 10 carbon atoms. (

Four

When the repeating unit contains one represented by the structural formula (5), it indicates that it is a copolymer containing another rataton. )

[0019] Further, the polyester of the present invention includes: 1) a dicarboxylic acid and a polyol

(It is a repeating unit represented by the structural formula (1). It may contain a repeating unit represented by the structural formulas (2) and Z or (3).) 2) Repeating from a hydroxycarboxylic acid Units (including repeating units represented by Structural Formula (4)), and 3) Repeating units from rataton (including repeating units represented by Structural Formulas (5), (7) !, ;)) Also includes copolymers containing two or more types of repeating units selected from 1) and 3).

[0020] Examples of the polycarbonate in the present invention include a trimethylene carbonate polymer, but are not limited thereto. The trimethylene carbonate polymer may contain one or more kinds of repeating units (Structural formulas (5) and (7)) which may be contained as the repeating units of the polylatatatone polymer.

In the continuous depolymerization of the present invention, the copolymer of polyester and polycarbonate as described above is used. A coalesced poly (ester-carbonate) can also be used.

As the polylactic acid used in the depolymerization method of the present invention, polylactic acid or a polylactic acid copolymer used for a molded article such as a film or a fiber can be used without any particular limitation. For example, examples of the homopolymer include poly (L-lactic acid), poly (DL-lactic acid), syndiotactic poly (DL-lactic acid), and atactic poly (DL-lactic acid).

Examples of the polylactic acid copolymer include polylactic acid as described above, such as j8-propiolatatone, β-butyrate rataton BL), ε-force prolatataton (εCL), 11-pindecanolide, 12-pindecanolide and the like. One-membered ring ratatones, cyclic carbonate monomers such as trimethylene carbonate (TMC) and methyl-substituted trimethylene carbonate and their oligomers, cyclic ester oligomers, hydroxy acids and esters thereof such as ricinoleic acid, linear carbonate oligomers, Examples thereof include copolymers of comonomers, such as linear ester oligomers, ester carbonate oligomers, and ether ester oligomers, which can be copolymerized with lactide and form a bond which can be affected by a hydrolase.

[0023] In the present invention, the hydrolase used is preferably Lino-IT due to the availability and heat stability of the enzyme, and among them, Linose derived from Candida antarctica and lipase derived from Rhizomucor miehei are particularly preferred. For example, as an immobilized enzyme derived from Candida antarctica, “Novozym 435 (trade name)” from Novozyms Japan Co., Ltd. IM (product name) ”. In addition, "Biopra _Se (trade name)" of Nagase ChemteX Corp., which is a protease derived from Bacillus subtilis, can also be used as a hydrolase.

The immobilized enzyme in the depolymerization of the present invention is used after being packed in a column, and the inner diameter and length of the column are appropriately determined in consideration of the flow rate of the reaction mixture flowing through the column and the like.

[0024] In the present invention, a supercritical fluid is used as a depolymerization main solvent. Examples of the supercritical fluid used include carbon dioxide and fluoroform (CHF).

Three

Is harmless, inexpensive, and nonflammable, and its critical point is about 31 ° C. and 7.4 MPa. Therefore, it is suitable as a medium used in the depolymerization and polymerization of the present invention, which easily reaches the critical point. Diacid carbon is suitable for handling relatively hydrophobic molecules, Furorohorumu are relatively suitable hydrophilic molecules in handling Uno _n In the depolymerization of the present invention, an organic solvent such as toluene is used to dissolve the polymer. The amount of the organic solvent used needs to be such that the raw material polymer is dissolved. For example, when dissolving polyhydroxybutyric acid in toluene, the ratio of the supercritical fluid flowing in the column to the toluene is about 1: 0.1-1: 0.6, preferably about 1: 0.2-1: 0.4. When the ratio of toluene is larger than 1: 0.6, the effects of using the supercritical fluid as described above, such as reactivity, reaction rate, and environmental compatibility, are difficult to obtain.In addition, the ratio of toluene is 1: 0. When this happens, the polymer dissolves, and thus the above ratio is appropriate.

As the organic solvent, other than toluene, xylene, benzene, and the like that do not inhibit the enzyme activity and dissolve the polymer well can be used.

[0025] Further, the concentration of the depolymerized polymer contained in the depolymerization reaction solution (mixture of the raw material polymer, the supercritical fluid, and the organic solvent) is preferably 0.1 to 50 g / L, particularly preferably 11 to 20 g / L. When the concentration is lower than 0.1 lg / L, the yield itself is particularly low, but the concentration is low, so that it is difficult to secure a sufficient amount of the depolymerized product to be obtained. The above range is preferable because the conversion rate to the polymerization product decreases.

[0026] When the supercritical fluid is supercritical carbon dioxide, its temperature is not lower than the temperature at which the supercritical fluid is maintained, and is about 80 ° C, preferably about 40-60 ° C, for example, enzyme activity, reaction rate, and temperature controllability. It is more preferable from the viewpoint of.

The pressure of the supercritical fluid diacid carbon is preferably about 13 to 15 MPa from the viewpoint of the yield of the oligomer.

The flow rate of the reaction solution in the enzyme packed column may be appropriately determined in consideration of the conversion rate to the oligomer, the molecular weight of the oligomer, the reaction rate, and the like. For example, if a stainless steel enzyme-filled column with an inner diameter of 7.8 mm and a length of 300 mm packed with 6.8 g of immobilized lipase derived from Candida antarctica (Novozym 435 Novozymes Japan Ltd), the total flow rate in the column (supercritical diacid) The raw polymer was completely depolymerized and disappeared even when the ratio of dani carbon to the organic solvent was increased from 0.5 mL / min to 1.51 mL / mm, but the molecular weight of the resulting oligomer was Gradually increased.

[0027] The depolymerized product obtained by the depolymerization method of the present invention contains a cyclic oligomer as a main component. For example, polycaprolactone is mainly produced from polycaprolactone and polytrimethylene Trimethylene carbonate is mainly produced from carbonate. The polyester power is mainly obtained from a cyclic polyester oligomer having a plurality of the unit units in the molecule. Furthermore, as for the polylactic acid power, a cyclic lactic acid oligomer having a plurality of lactic acid units in a molecule is mainly obtained.

When depolymerization is carried out by chemical decomposition or thermal decomposition, both ends of the resulting low molecular weight compound are irregular, and it is impossible to repolymerize this to form a polymer. The cyclic oligomer obtained by the polymerization method can be easily repolymerized. In addition, there is also an advantage that there is no elimination when the cyclic oligomer is repolymerized.

Furthermore, compared to the case where continuous depolymerization is performed using only an organic solvent, the rate of formation of repolymerizable cyclic oligomers is significantly improved.

[0028] The continuous depolymerization apparatus used in the continuous depolymerization method as described above includes at least a supercritical fluid generator, a column packed with a hydrolytic enzyme, a knock pressure regulator, and a reaction mixture containing a depolymerized product. Means for separating a substance, a means for sending a supercritical fluid produced by a supercritical fluid generator to the column, and a means for sending an organic solvent solution of a raw material polymer to the column. .

[0029] Knock pressure regulator force The gaseous substance from the released supercritical fluid may be collected or released into the atmosphere as it is, but is preferably recovered and reused. In the case of re-use, the configuration of the above-mentioned apparatus is further provided with a means for returning gasified substances from the supercritical fluid discharged from the knock pressure regulator to the supercritical fluid generation apparatus. The means includes means for recovering gaseous matter from the supercritical fluid, which also releases the back pressure regulator force, and sending it to the supercritical fluid generator.

FIG. 9 shows a conceptual diagram of an example of a continuous depolymerization apparatus using supercritical carbon dioxide as a supercritical fluid.

In FIG. 9, reference numeral 10 denotes a supercritical carbon dioxide generator, which is, for example, a carbon dioxide condenser (not shown), a pressurizing pump, and a normal one having heat exchange. Numeral 12 indicates a supply means of carbon dioxide (eg, a liquid carbon cylinder). Reference numeral 20 denotes a thermostat provided with a hydrolytic enzyme-filled column 22 therein, which is provided with a heating device and a temperature control device (not shown) so as to keep the column temperature constant. 30 is a back pressure regulator (back pressure control device) ), The pressure of the entire reaction system is controlled, and the reaction liquid after the completion of the reaction is separated from a carbon dioxide gas, a mixture of an organic solvent and a depolymerized product. A commercially available back pressure regulator can be used. Numeral 40 denotes means for separating the organic solvent solution of the depolymerized product into an organic solvent and a depolymerized product, and includes, for example, an evaporator for removing the organic solvent.

The means for sending the supercritical fluid produced by the supercritical fluid generator to the column has a supercritical carbon dioxide sending pump 14 and a line (pipe) L1 for supplying the supercritical carbon dioxide. The means for sending the organic solvent solution of the raw material polymer to the column includes a liquid feed pump 16 for the raw material polymer solution and a line (tube) L2 for supplying the organic solvent solution of the raw material polymer.

Further, L3 indicates a line (pipe) for recovering the carbon dioxide gas that also releases the back pressure regulator force and returning it to the supercritical fluid generator.

[0031] In this embodiment, the carbon dioxide is returned to the supercritical fluid again by the supercritical carbon dioxide generator, but is released from the back pressure regulator 30 into the air.

[0032] The method of using the apparatus is as follows. First, liquid carbon dioxide or the like is supplied from the carbon dioxide supply means 12 to the supercritical carbon dioxide generator 10 to generate supercritical carbon dioxide, and the liquid is sent through the line L1 by the liquid sending pump 14. Send the liquid to the column. On the other hand, the raw material polymer is dissolved in an organic solvent, and the solution is sent toward the column through the line L2 by the solution sending pump 16. The supercritical carbon dioxide and the raw polymer solution merge before entering the column, and form a mixed solution and flow into the column. In the thermostat 20, temperature control has already been performed to maintain the hydrolytic enzyme packed column 22 at the reaction temperature. The mixture of the supercritical carbon dioxide and the raw material polymer solution flows into the temperature-controlled column, and comes into contact with the hydrolase filled in the column to perform depolymerization. The reaction solution flowing out of the column has completed the depolymerization reaction, and a depolymerized oligomer has been generated. The back pressure regulator 30 controls the pressure of the whole reaction system.

Next, the reaction solution after the completion of the reaction enters the back pressure regulator 30, and is separated into two, that is, a carbon dioxide gas and a mixture of an organic solvent and a depolymerized product. Separated The carbon dioxide gas passed through the line L3 is again introduced into the supercritical carbon dioxide generator and reused. On the other hand, the mixture of the organic solvent and the depolymerized product is separated into the organic solvent and the depolymerized product by means 40 for separating the depolymerized product, and the depolymerized product is recovered.

Example

[0033] The present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The following continuous depolymerization was performed using an apparatus as shown in FIG.

Example 1 [Continuous depolymerization of atactic poly (RS-3-hydroxybutyric acid)]

A stainless steel column with an inner diameter of 7.8 mm and a length of 300 mm is filled with 6.8 g of Candida antarctica-derived immobilized lipase (Novozym 435 Novozymes Japan, Ltd) to form a hydrolytic enzyme filling ram. The temperature was controlled so that the inside was maintained at 40 ° C. A 1% toluene solution of atactic poly (RS-3-hydroxybutyric acid) (Mn = 110,000) was applied to this enzyme-packed column at a flow rate of 0.1 mL / min, and supercritical carbon dioxide at 15 MPa and a flow rate of 0.4 mL / min. Passed through. From the back pressure regulator, a toluene solution of the decomposition product and gaseous carbonate were separately collected. Toluene was distilled off from the obtained toluene solution under reduced pressure to obtain a depolymerized product.

The molecular structure of the obtained depolymerized product was analyzed by ¹ H NMR analysis, MALDI-TOF MS analysis and SEC analysis. As a result, Ή NMR analysis and MALDI-TOF MS analysis confirmed that the oligomer obtained by the depolymerization was a substantially complete cyclic body centered on a heptamer (see FIGS. 1 and 2). In addition, SEC analysis confirmed that the original polymer portion had completely disappeared and had been converted into an oligomer having a molecular weight of Mn = 500 (see Fig. 3). Furthermore, hexamers were separated from the resulting oligomers by preparative high performance liquid chromatography using supercritical carbon dioxide as a mobile phase, and subjected to structural analysis by NMR. As a result, no peak derived from the terminal group (hydroxyl group) was observed within the range shown by the dotted line in FIG. 4 (A). Further, the result of MALDI-TOF MS analysis of the hexamer is shown in FIG. 4 (B). From the results shown in FIGS. 4 (A) and (B), it was confirmed that the hexamer was a cyclic body.

Example 2 [Continuous depolymerization of atactic poly (RS-3-hydroxybutyric acid)] The same hydrolytic enzyme packed column as in Example 1 was prepared, and the temperature was similarly adjusted to 40 ° C. To this, a 1% toluene solution of atactic poly (RS-3-hydroxybutyric acid) (Mn = 110,000) was passed at a flow rate of 0.3 mL / min, and supercritical carbon dioxide was passed at 15 MPa and a flow rate of 1.2 mL / min. The toluene solution of decomposition products and carbon dioxide were separately collected from the back pressure regulator. From the resulting toluene solution, toluene was distilled off under reduced pressure to obtain a depolymerized product. The molecular structure of the obtained depolymerized product was analyzed by ¹ H NMR analysis, MALDI-TOF MS analysis and SEC analysis. As a result, according to Ή NMR analysis and MALDI-TOF MS analysis, the oligomer obtained by the depolymerization was almost a perfect cyclic body. Also, SEC analysis confirmed that the original polymer portion had completely disappeared and had been converted to an oligomer having a molecular weight of Mn = 1,000. The spectrum and the like were the same as in Example 1.

Example 3 [Continuous Depolymerization of Poly (ε-force prolatataton)]

The same hydrolytic enzyme packed column as in Example 1 was prepared, and the temperature was similarly adjusted to 40 ° C. To this, a 1% toluene solution of poly-force prolatatatone (Mn = 110,000) was passed at a flow rate of 0.1 mL / min, and supercritical carbon dioxide was passed at a flow rate of 15 MPa and a flow rate of 0.4 mL / min. From the back pressure regulator, a decomposition product toluene solution and carbon dioxide were separately collected. From the resulting toluene solution, toluene was distilled off under reduced pressure to obtain a depolymerized product.

The molecular structure of the obtained depolymerized product was analyzed by ¹ H NMR analysis, MALDI-TOF MS analysis and SEC analysis. As a result, Ή NMR analysis and MALDI-TOF MS analysis confirmed that the oligomer obtained by the depolymerization was a substantially complete cyclic body mainly composed of a dimer. Also, SEC analysis confirmed that the original polymer portion had completely disappeared and had been converted into an oligomer having a molecular weight of Mn = 200 (see FIG. 5).

Example 4 [Continuous Depolymerization of Poly (butylene adipate)]

The same hydrolytic enzyme packed column as in Example 1 was prepared, and the temperature was similarly adjusted to 40 ° C. To this, a 1% toluene solution of poly (butylene adipate) (Mn = 18,000) was passed at a flow rate of 0.1 mL / min, and supercritical carbon dioxide was passed at 15 MPa and a flow rate of 0.4 mL / min. From the back pressure regulator, a decomposition product toluene solution and carbon dioxide gas were separately collected. From the obtained toluene solution, toluene was distilled off under reduced pressure to obtain a depolymerized product.

The molecular structure of the obtained depolymerized product was analyzed by ¹ H NMR analysis, MALDI-TOF MS analysis and Analyzed by SEC analysis. As a result, Ή NMR analysis and MALDI-TOF MS analysis confirmed that the oligomer obtained by the depolymerization was a substantially complete cyclic body mainly composed of a dimer. In addition, SEC analysis confirmed that the original polymer portion had completely disappeared and had been converted into an oligomer having a molecular weight of Mn = 500 (see FIG. 6).

Example 5 [Continuous Depolymerization of Poly (L-lactic acid-ε-force prolatataton) copolymer]

The same hydrolytic enzyme packed column as in Example 1 was prepared, and the temperature was similarly adjusted to 40 ° C. Then, a 1% toluene solution of a poly (L-lactic acid ε-caprolataton) copolymer (Mn = 80,000, L_lactic acid: ε-caprolataton = 4: 1) was added at a flow rate of O.lmL / min. In addition, supercritical carbon dioxide was passed at a flow rate of 15 MPa and a flow rate of 0.4 mL / min. The toluene solution of decomposition products and carbon dioxide gas were separately collected from the back pressure regulator. From the obtained toluene solution, toluene was distilled off under reduced pressure to obtain a depolymerized product.

The molecular structure of the obtained depolymerized product was analyzed by ¹ H NMR analysis, MALDI-TOF MS analysis and SEC analysis. As a result, according to によって NMR analysis and MALDI-TOF MS analysis, the oligomer portion obtained by the depolymerization was almost completely cyclic. Also, SEC analysis confirmed that the original polymer portion had completely disappeared and had been converted to an oligomer having a molecular weight of Mn = 700 (see Fig. 7).

Example 6 [Continuous Depolymerization of Poly (trimethylene carbonate)]

The same hydrolytic enzyme packed column as in Example 1 was prepared, and the temperature was similarly adjusted to 40 ° C. To this, a 1% toluene solution of poly (trimethylene carbonate) (Mn = 5,000) was passed at a flow rate of 0.1 mL / min, and supercritical carbon dioxide was passed at a flow rate of 15 MPa and a flow rate of 0.4 mL / min. The toluene solution of decomposition products and carbon dioxide were separately collected from the back pressure regulator. From the resulting toluene solution, toluene was distilled off under reduced pressure to obtain a depolymerized product.

The molecular structure of the obtained depolymerized product was analyzed by ¹ H NMR analysis, MALDI-TOF MS analysis and SEC analysis. As a result, according to Ή NMR analysis and MALDI-TOF MS analysis, the oligomer portion obtained by the depolymerization was a trimethylene carbonate monomer and a linear oligomer homolog. In addition, SEC analysis confirmed that the original polymer portion had completely disappeared and had been converted to oligomer.

[0039] Comparative Example 1 In Example 2, a toluene solution (10 mg / mL) of atactic poly (RS-3-hydroxybutyric acid) was passed through the hydrolytic enzyme packed column at a flow rate of 0.5 mL / min without flowing supercritical carbon dioxide. It was confirmed that undecomposed atactic poly (RS-3-hydroxybutyric acid) remained in the depolymerized product (see FIG. 8).

Industrial applicability

[0040] The depolymerization method of the present invention can provide a polyester, polycarbonate, or polylactic acid capable of producing a repolymerizable cyclic oligomer at a good production rate, and can perform a large amount of treatment with high efficiency. A useful way to do that. Further, according to the present invention, it is possible to construct a completely circulating type polymer material utilization system that is environmentally acceptable and can completely reuse carbon resources. Extremely large.

Explanation of symbols

[0041] 10 Supercritical carbon dioxide generator

20 constant temperature bath

22 Hydrolysis enzyme packed column

30 Knock pressure regulator

40 Means for separating depolymerized products

Claims

The scope of the claims

[1] The supercritical fluid and an organic solvent solution of polyester, polycarbonate or polylactic acid are continuously passed through the column packed with the hydrolase, and the polyester, polycarbonate or polylactic acid is depolymerized by the hydrolase, and the hydrolase is decomposed. A method for continuously depolymerizing polyester, polycarbonate or polylactic acid, wherein a depolymerized product is separated from a reaction mixture containing a depolymerized product flowing out of a packed column.

[2] The method for continuous depolymerization of polyester, polycarbonate or polylactic acid according to claim 1, wherein the supercritical fluid is supercritical carbon dioxide.

[3] The method for continuous depolymerization of polyester, polycarbonate or polylactic acid according to claim 1 or 2, wherein the hydrolase is an immobilization enzyme.

[4] Supercritical fluid generator, hydrolytic enzyme packed column, back pressure regulator 1, means for separating depolymerized product from reaction mixture containing depolymerized product, supercritical fluid produced by supercritical fluid generator The continuous depolymerization for use in the continuous depolymerization method according to claim 1, further comprising: means for sending a fluid to the column, and means for sending an organic solvent solution of polyester, polycarbonate, or polylactic acid to the column. apparatus.

[5] The continuous depolymerization apparatus according to claim 4, further comprising: means for returning a gasified substance from the released supercritical fluid to the supercritical fluid generation device.