KR20070055446A - Process for manufacturing polylactic acid, lactic acid manufacturing apparatus, and polylactic acid manufacturing apparatus - Google Patents

Abstract

In the production method of the polylactic acid which ferments vegetable starch and lactic acid bacteria to produce a lactic acid, depolymerization of the lactic acid to synthesize a polylactic acid,

A direct current in a mixture containing said vegetable starch, said lactic acid bacteria and said lactic acid in a fermentation tank having at least one pair of electrodes, a partition wall and said partition wall, said enrichment section being provided on the cathode side of said electrode; Fermentation and concentration step of flowing and storing the lactic acid to the concentration unit by electrofiltration;

And a polymerization step of synthesizing the polylactic acid by heating and deshrink-polymerizing the lactic acid in the polymerization tank to which the lactic acid stored in the concentration unit is supplied.

Lactic acid, polylactic acid, vegetable starch, lactic acid bacteria, polymerization

Description

Process for producing polylactic acid, lactic acid production apparatus and polylactic acid production apparatus {PROCESS FOR MANUFACTURING POLYLACTIC ACID, LACTIC ACID MANUFACTURING APPARATUS, AND POLYLACTIC ACID MANUFACTURING APPARATUS}

Figure 1 is a schematic diagram conceptually showing the configuration of the lactic acid production apparatus of the present invention.

2 is a cross-sectional view for explaining a specific aspect of the fermentation tank according to the present invention.

3 is an explanatory diagram for explaining a specific aspect of the fermentation tank according to the present invention.

Figure 4 is a schematic diagram conceptually showing the configuration of the polylactic acid production apparatus of the present invention.

5 is a cross-sectional view for explaining a specific embodiment of the polymerization tank and the electric dehydration tank according to the present invention.

FIG. 6 is a perspective view showing a configuration example of a static mixer used for an electric dehydration tank. FIG.

7 is a graph showing the relationship between lactic acid concentration and electric penetration voltage.

8 is a graph showing the relationship between the polymerization temperature and the polymerization time for the polymerization of polylactic acid.

The present invention relates to a process for producing polylactic acid, which is biodegradable plastics, and to a lactic acid production apparatus and a polylactic acid production apparatus.

Biodegradable plastics perform as well as ordinary plastics during their use, and are rapidly decomposed by the microorganisms in the natural environment (for example, in soil, etc.). It refers to plastic that becomes carbon dioxide, and is currently attracting attention in wastes.

As biodegradable plastics, various products have been announced until now. For example, polylactic acid obtained by dehydrating a lactic acid obtained by fermenting starch, such as corn or potato, by lactic acid bacteria can be exemplified, and is used in agricultural multi-film or posting-pack.

Polylactic acid has been known to be able to obtain lactic acid by lactic acid fermentation by acting lactic acid bacteria to vegetable starch, which has conventionally been deshrunk-polymerized lactic acid. However, according to the conventional method, the pH of the reaction solution decreases in the course of fermentation, and the activity of lactic acid bacteria is often inhibited. It is difficult to obtain a high concentration of lactic acid with good efficiency. It is estimated that the pH fall of such a reaction liquid is caused by the lactic acid produced by the fermentation remaining in the fermenter when the vegetable starch and the lactic acid bacteria are acted upon.

In addition, polylactic acid is obtained by deshrink-condensation polymerization of a lactic acid by heating with agitation, by adding an appropriate amount of a catalyst (e.g., a mixture of ruthenium oxide and titanium oxide) to the concentrated lactic acid. It is known. At this time, it is necessary to discharge the water generated in the deshrinkable polymerization reaction to the outside of the apparatus, and as described in Japanese Patent Laid-Open No. 2003-335850, conventionally, water is evaporated under reduced pressure as a method of discharging such water. I) A method of making is used.

However, by the method of evaporating water under reduced pressure, since the viscosity of a polymer becomes high as a polymerization reaction progresses, there exists a drawback that the dissociation rate of water becomes slow and it is impossible to perform efficient dehydration.

The present invention has been made to solve the above problems, a method for producing a polylactic acid which can obtain a polylactic acid having a desired molecular weight in a high efficiency or a short time, and a lactic acid production apparatus that can obtain a high concentration of a lactic acid in a high efficiency, and in a high efficiency or a short time An object of the present invention is to provide a polylactic acid production apparatus capable of obtaining a polylactic acid having a sufficient molecular weight.

In order to achieve the above object, the present invention of the first embodiment is a method of producing a polylactic acid in which a polylactic acid is synthesized by fermenting vegetable starch and lactic acid bacteria to produce lactic acid, and derivatizing the lactic acid to synthesize polylactic acid. A direct current flows through the mixture containing the vegetable starch, the lactic acid bacteria and the lactic acid in a fermentation tank provided with an electrode, a partition wall, and a thickening section separated by the partition wall, and the thickening section is provided on the cathode side of the electrode. And a fermentation concentrating step of moving the lactic acid to the concentrating unit and storing the lactic acid by electroinfiltration, and polymerizing polylactic acid by dehydrating and polymerizing the lactic acid by heating the lactic acid in a polymerization tank to which the lactic acid stored in the concentrating unit is supplied. It provides a polylactic acid production method comprising the step.

The present invention of the second embodiment has a polymerization step of synthesizing a lactic acid polymer by heating and dehydrating and polymerizing a lactic acid, and a dehydrating part divided by at least a pair of electrodes, a partition wall and the partition wall, and the dewatering part of the electrode An electric dehydration step of flowing a direct current through the lactic acid polymer polymerized in the polymerization step in the electric dehydration tank provided on the cathode side and transferring water in the lactic acid polymer to the dehydration unit by electroinfiltration. Provides a process for the preparation of lactic acid.

The present invention of the third embodiment has a condensation section divided by at least a pair of electrodes, a partition wall and the partition wall, and the concentrating section is provided with a fermentation tank provided on the cathode side of the electrode, and vegetable starch and lactic acid bacteria into the fermentation tank. A raw material introduction means, flowing a direct current through a mixture of the lactic acid obtained by fermenting the vegetable starch and the lactic acid bacteria in the fermentation tank and the vegetable starch and the lactic acid bacteria, and transferring the lactic acid by electroporation to the concentrating unit. Provides a lactic acid production device.

The present invention of the fourth embodiment is divided by lactic acid introduction means into which lactic acid is introduced, polymerization means for heating and dehydrating and polymerizing the lactic acid introduced from the lactic acid introducing means, and at least one pair of electrodes, partition walls and partition walls. And a dehydration portion, wherein the dehydration portion has electrical dehydration means provided on the cathode side of the electrode, wherein the electrode dehydration means flows a direct current through the depolymerized lactic acid polymer in the polymerization means and supplies water in the lactic acid polymer. Provided is a polylactic acid production apparatus which moves to the dehydration unit by infiltration to dehydrate it.

The polylactic acid production method of the present invention is a method for producing a polylactic acid to synthesize a polylactic acid by fermenting vegetable starch and lactic acid bacteria to produce a lactic acid, depolymerization of the lactic acid, at least a pair of electrodes, partitions, In the fermentation tank provided with the enrichment part divided by the said partition, and the said enrichment part is provided in the cathode side of the said electrode, DC current is sent to the mixture containing the said vegetable starch, the said lactic acid bacterium, and the said lactic acid, and the said lactic acid is passed through an electropenetration And a fermentation concentrating step of moving to the concentrating unit and storing the same, and a polymerization step of synthesizing polylactic acid by heating and dehydrating the lactic acid in a polymerization tank to which the lactic acid stored in the concentrating unit is supplied. do.

According to the production method of the polylactic acid of the present invention (hereinafter sometimes referred to as the "manufacturing method of the present invention"), the lactic acid in the fermentation tank is used in the production process of the lactic acid used in the production of the polylactic acid, using an electropenetrating action. It can be isolated from unfermented lactic acid bacteria and vegetable starch. Therefore, the lactic acid concentration in the mixture related to the production of lactic acid directly in the fermentation tank can be kept low, and the pH drop of the mixture can be suppressed. Accordingly, according to the production method of the present invention, a high concentration of lactic acid can be obtained, and polylactic acid having a desired molecular weight can be efficiently produced by using it. The term "electropenetration" refers to the movement of an electrically neutral solvent due to a potential difference through a porous material such as a membrane.

In addition, according to the production method of the present invention, in the polymerization step in an electric dehydration tank having at least a pair of electrodes, a partition wall, and a dewatering part divided by the partition wall, and the dewatering part is provided on the cathode side of the electrode. It is possible to include an electric dehydration step of flowing a direct current to the dehydration-polymerized lactic acid polymer and moving water in the lactic acid polymer to the dewatering part by electroinfiltration.

That is, the polylactic acid production method according to the second embodiment of the present invention has a polymerization step of synthesizing a lactic acid polymer by heating and dehydrating and polymerizing a lactic acid, and at least one pair of electrodes, a partition wall, and a dehydration part separated by the partition wall. In addition, the dehydration unit flows a direct current through the lactic acid polymer polymerized in the polymerization step in an electric dehydration tank provided on the cathode side of the electrode, and moves the water in the lactic acid polymer to the dehydration unit by electroporation to perform an electrical dehydration step. Characterized in that it comprises a.

According to the production method of the present invention, it is possible to move the water contained in the lactic acid polymer (polylactic acid) dehydrated and condensation-polymerized in the polymerization step in the electric dehydration step to the dehydration part by electroporation. As a result, the polymerization of the lactic acid polymer proceeds, thereby making it possible to perform efficient dehydration even in a state where the viscosity is high. In addition, the term "lactic acid polymer" as used herein means a step prior to the polylactic acid having a desired molecular weight in the production method or each device of the present invention, that is, the oligomer of the lactic acid and the polylactic acid that has not yet reached the desired molecular weight. In addition, the lactic acid polymer includes a state in which water generated in the deshrinkable polymerization reaction of lactic acid is contained.

In the production method of the present invention, corn starch can be optimally used as a vegetable starch.

The lactic acid production apparatus of the present invention includes a fermentation tank having at least one pair of electrodes, partition walls, and partition walls, and the concentration section is provided on the cathode side of the electrode, and vegetable starch and lactic acid bacteria are introduced into the fermentation tank. A raw material introduction means, flowing a direct current through a mixture of the lactic acid obtained by fermenting the vegetable starch and the lactic acid bacteria in the fermentation tank and the vegetable starch and the lactic acid bacteria, and transferring the lactic acid by electroporation to the concentrating unit. It features.

The lactic acid production apparatus of the present invention can separate the lactic acid in the fermentation tank into unfermented lactic acid bacteria and vegetable starch by using an electropenetrating action by flowing a DC current through the mixture in the fermentation tank. Therefore, it is possible to keep the concentration of lactic acid in the mixture associated with the production of lactic acid directly in the fermentation tank, and to suppress the pH drop of the mixture. Accordingly, according to the lactic acid production apparatus of the present invention, a high concentration of lactic acid can be efficiently produced. In addition, the lactic acid production apparatus of the present invention can make the anode of the electrode into a mesh shape.

The lactic acid production apparatus of the present invention, the lactic acid storage tank for discharging the lactic acid moved to the concentrating unit, the lactic acid storage tank for supplying the lactic acid discharged from the discharge pipe and stores the lactic acid, and the lactic acid in the lactic acid storage tank to the concentrating unit It may be provided with a supply pipe for supplying, and the discharge means for discharging the lactic acid in the lactic acid storage tank to the outside.

In the lactic acid production apparatus of the present invention, it is possible to increase the concentration of lactic acid by circulating the concentrated portion of the fermentation tank and the lactic acid storage tank by connecting the discharge pipe and the supply pipe.

The polylactic acid production apparatus of the present invention is divided by lactic acid introduction means into which lactic acid is introduced, polymerization means for heating and dehydrating and polymerizing the lactic acid introduced from the lactic acid introducing means, and at least one pair of electrodes, partition walls, and partition walls. And a dehydration portion, wherein the dehydration portion has electrical dehydration means provided on the cathode side of the electrode, wherein the electrode dehydration means supplies a direct current to the depolymerized lactic acid polymer in the polymerization means, and conducts water in the lactic acid polymer. It is characterized in that the dehydration by moving to the dehydration unit by infiltration.

According to the polylactic acid production apparatus of the present invention, water contained in the lactic acid (polylactic acid) dehydrated and condensed in a polymerization tank can be moved to the dehydration portion by electroporation. Accordingly, even in a state where the polymerization of the polylactic acid proceeds and the viscosity is high, efficient dehydration can be performed, and a polylactic acid having a desired molecular weight can be produced in a high efficiency or in a short time.

In addition, the polylactic acid production apparatus of the present invention further comprises a raw material introduction means for introducing vegetable starch and lactic acid bacteria, and a fermentation tank, the fermentation tank being divided by at least one pair of electrodes, a partition wall and the partition wall to the cathode side of the electrode. And a fermentation concentrating means provided with a condensing part installed in the fermentation concentrating means, wherein the fermentation concentrating means flows a DC current to the lactic acid obtained by fermenting the vegetable starch and lactic acid bacteria introduced from the raw material introduction means in the fermenter, and concentrating the condensation by electric infiltration. And to store the lactic acid in the concentrating unit, and to supply the lactic acid stored in the concentrating unit to the polymerization means.

The polylactic acid production apparatus of the present invention can further supply a high concentration of lactic acid to the polymerization tank by providing a fermentation concentration means. In addition, the lactic acid production process and the polylactic acid polymerization process can be carried out continuously, so that an efficient polylactic acid can be produced.

The polylactic acid production apparatus of the present invention includes a discharge pipe for discharging the lactic acid stored in the concentrating unit, the lactic acid storage tank for supplying the lactic acid discharged from the discharge pipe and storing the lactic acid, to the fermentation concentrating means, and the lactic acid. And a supply pipe for supplying the lactic acid in the storage tank to the concentrating unit, and a supply unit for supplying the lactic acid in the lactic acid storage tank to the polymerization means.

In the polylactic acid production apparatus of the present invention, the concentration of lactic acid and the lactic acid storage tank are circulated by connecting the discharge pipe and the supply pipe, thereby increasing the concentration of lactic acid. In addition, the lactic acid production apparatus of the present invention may be configured in the above-described positive electrode in a mesh shape.

In the polylactic acid production apparatus of the present invention, the polymerization means has openings at both ends, the hollow gas to which the lactic acid is supplied from the opening in one direction, and the hollow gas is built into the hollow gas from the opening in the one direction to the opening in the other direction. A rod-shaped rotating body having a spiral groove narrowing in width of the groove, and heating means for heating the inside of the hollow gas, and rotating the rod-shaped rotating body from the opening in the one direction to the opening in the other direction. It can be configured to compress by heat-pressing toward. The rod-shaped rotating body may have a spiral groove in which the groove width is narrowed from the opening in one direction to the opening in the other direction.

According to the polylactic acid production apparatus of the present invention, when the rod-shaped rotating body rotates, the lactic acid is pressurized while being heated from the lactic acid supply side installed in one direction of the hollow gas toward the extrusion port in the other direction along the spiral groove, and compressed at a desired pressure. can do. Accordingly, the lactic acid can be efficiently heated to perform deshrinkment polymerization.

The internal structure of the hollow gas can be formed into any shape such as circular, elliptical, spherical or rectangular in cross section, but the cross section is circular in that the pressure applied to the miscarriage by the rod rotating body rotating inside the gas is uniform. It is desirable to. Further, the spiral groove can be provided from one end of the rod-shaped rotating body to the other end so as to gradually narrow the spiral pitch (groove width) from the lactic acid supply side to the exit side when embedded in the hollow gas, thereby conveying the plant material. For this reason, it is preferable that the rod-shaped rotary body be a substantially circular rod-shaped cross section from the point that efficient and uniform compression is possible.

In the polylactic acid production apparatus of the present invention, the electric dehydration means is installed inside the hollow body and the hollow body through which the lactic acid is inserted, and is disposed adjacently so as to reversely rotate with each other in the direction of insertion of the lactic acid. It is possible to comprise a plurality of rotary blades.

The polylactic acid production apparatus of the present invention has a structure in which a rotary blade rotates under fluid pressure by a flow of a fluid through which the rotor blade is inserted into the inside of a body, that is, a lactic acid polymer (polylactic acid) polymerized in a polymerization tank (for example, a force in a flow direction) The wing-shaped stator etc. which attached the twister so that rotation may be received may be preferable, and it can stir continuously without connecting a drive part. The rotary blades can be installed so that a plurality of adjacent blades can be reversely rotated (ie, alternately rotated in opposite directions) with the direction of insertion of the fluid as the rotation axis. Thus, water is stirred by electroporation by stirring the lactic polymer. It can be easy to separate. As a result, it is possible to miniaturize the dewatering device without accompanied by a decrease in the dewatering efficiency. The rotary blade may be configured to rotate by a motor or magnetic force in contact with a power source. In addition, the inner structure of the hollow body is configured to be obtained by inserting a lactic acid polymer or the like, the cross section can be configured in any shape, such as circular, elliptical, spherical, square, and particularly, a hollow hollow cross section.

In addition, it is preferable that a power source is connected to the rotary blade, and the electric dewatering means functions as an anode of the electrode. As a result, water mixed in the lactic acid polymer is easily brought into contact with the positive electrode due to the stirring of the rotary blade, and dehydration can be performed more efficiently.

Corn starch may be optimally used as the plant starch that may be used in the lactic acid production apparatus and the polylactic acid production apparatus of the present invention. Any vegetable starch may be used in the present invention, but it is preferable to use corn starch in view of work efficiency, availability, and quality of the polylactic acid obtained.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings. In addition, although the case where corn starch is used as a vegetable starch is demonstrated below, this invention is not limited to these embodiment.

<< Production method of polylactic acid >>

The polylactic acid production method of the present invention is roughly divided into a fermentation concentration step of fermenting cornstarch and lactic acid bacteria to produce lactic acid and concentrating it, and a polymerization step of polymerizing the resulting lactic acid. Hereinafter, the case where the lactic acid production apparatus and polylactic acid production apparatus of the present invention are used in each step will be described as an example.

<Fermentation Concentration Process>

The lactic acid production apparatus of the present invention using FIGS. 1 to 3 will be described. Figure 1 is a schematic diagram conceptually showing the configuration of the lactic acid production apparatus of the present invention. As shown in FIG. 1, the lactic acid production apparatus 10 of the present invention includes a mixing device 20, a fermentation tank 30, and a lactic acid storage tank 50. The lactic acid production apparatus 10 ferments a mixture including cornstarch and lactic acid bacteria mixed in the mixing apparatus 20 in a fermentation tank 30 to generate lactic acid, and separates the resulting lactic acid from other mixtures, lactic acid storage tank 50 By circulating and concentrated between and to obtain a high concentration of lactic acid.

The mixing device 20 is not particularly limited and is a device provided with known mixing means such as a stirrer. The mixing device 20 is supplied with additives such as water, other enzymes, etc. in addition to cornstarch and lactic acid bacteria. At this time, the mixing ratio (mass ratio x: y) of starch (X) and lactic acid bacteria (Y) in the mixture is preferably 1,000: 0.1 to 1,000: 10, and more preferably 1,000: 0.5 to 1,000: 5. In addition, corn starch may be configured to be mixed with lactic acid bacteria after being subjected to saccharification treatment in advance. Examples of the additives include salt, calcium carbonate, various enzymes, and the like. At this time, as content of the said calcium carbonate, about 0.5-1 mass% is preferable with respect to a mixture. The mixing device 20 mixes the supplied cornstarch and the like into a mixture, and introduces the mixture into the fermentation tank 30.

The fermentation tank 30 has at least one pair of electrodes composed of an anode 32 and a cathode 34, and these electrodes are connected to a power source (not shown). In the tank of the fermentation tank 30, the partition 36 is separated by a partition wall 36 so as to be spaced apart between the anode 32 and the cathode 34. The side at which the cathode 34 is provided at the boundary of the partition 36 is provided. The fermentation part 40 is provided in the side in which the condensation part 38 is equipped with the anode 32 further. The mixture supplied from the mixing device 20 is introduced into the fermentation 40. Moreover, although it does not specifically limit as a material which comprises the fermentation tank 30, Titanium (Ti) is preferable from a viewpoint of rust prevention property.

The positive electrode 32 and the negative electrode 34 are preferably made of a precious metal such as platinum (Pt), and are preferably those obtained by plating platinum on titanium or by imposing ruthenium on the surface thereof. It is available. The electrode can be obtained, for example, by rolling and plating platinum (Pt) on a titanium (Ti) plate, followed by electroplating ruthenium (Ru) and firing it in an oxygen atmosphere. In addition, the electrode can be obtained by electroplating platinum on a titanium plate and firing in an oxygen atmosphere. Moreover, as for the baking temperature, about 650-700 degreeC is preferable in all.

The positive electrode 32 and the negative electrode 34 are connected to a power source (not shown), and by supplying a current from such a power source, a direct current can be passed through the mixture in the fermentation part 40. In this way, when a direct current flows through the mixture in the fermentation section 40, the current penetrating action causes the liquid lactic acid or water to flow from the anode 32 side to the cathode 34 side (arrow A in FIG. 1). Can be moved.

The partition wall 36 can pass a liquid (lactic acid) in the mixture, and any structure may be used as long as it suppresses the passage of solid matter such as cornstarch. The partition wall 36 can have a mesh shape, for example. The material constituting the partition wall 36 can be used without particular limitation as long as it has a certain degree of resistance to lactic acid and the like, but titanium (Ti) is preferable from the viewpoint of rust resistance. In addition, the partition 36 itself mentioned later may be formed with the metal which comprises the anode 32, and such partition 36 itself may be used as the anode 32. As shown in FIG. In this case, the space spaced apart from the condensing part 38 by the partition 36 becomes a fermentation part. Moreover, a polyimide film or the like can also be suitably used.

The concentrating part 38 is formed by dividing the inside of the fermentation tank 30 into the partition 36, and is installed in the side in which the negative electrode 34 is provided. The concentrate 38 stores the lactic acid that has passed through the partition wall 34 by an electropenetrating action. Hereinafter, the lactic acid which passed through the partition 36 and moved to the enrichment part is called "high concentration heritage." In addition, one end of the discharge pipe 42 and one end of the supply pipe 44 are connected to the concentrating unit 38, and is configured to be capable of circulating a highly concentrated heritage between the lactic acid storage tank 50.

One end of the circulation pipe 46 is connected to the fermentation part 40 of the fermentation tank 30. In addition, the other end of the circulation pipe 46 is connected to the mixing device 20, and supplies unreacted corn starch (starch), lactic acid bacteria, etc. in the fermentation part 40 to the mixing device 20 again, and reuses it. It is configured to be possible. Moreover, the fermentation part 40 is provided with the discharge port which abbreviate | omits illustration, and is comprised so that fermentation dregs, such as cornstarch after fermentation, can be discharged | emitted to the outside. In the embodiment, the mixture is circulated between the mixing device 20 and the fermentation section 40. However, the circulation mode is arbitrary.

The lactic acid storage tank 50 is configured to be supplied with a high concentration of lactic acid fermented and separated from the fermentation tank 30 and to store the high concentration of lactic acid. In addition, one end of the discharge pipe 42 and one end of the supply pipe 44 are connected to the lactic acid storage tank 50 so that the highly concentrated heritage can be circulated between the concentration section 38 of the fermentation tank 30. In this way, a more concentrated lactic acid can be obtained by circulating the highly concentrated heritage between the concentration unit 38 and the lactic acid storage tank 50. In addition, in this embodiment, although the high concentration heritage is circulated between the concentrating part 38 and the lactic acid storage tank 50, this circulation aspect is arbitrary.

A lactic acid discharge pipe 52 is connected to the lactic acid storage tank 50, and is configured to discharge the high concentration heritage stored in the lactic acid storage tank 50 to the outside of the apparatus.

The flow of lactic acid production in the lactic acid production apparatus of the present invention will be described. First, lactic acid bacteria, cornstarch, water, and the like are supplied to the mixing apparatus 20 and mixed, and then introduced into the fermentation section 40 of the fermentation tank 30. In the fermentation part 40, the temperature is maintained at about 40 degreeC, the pH of a mixture is about 5-6, and it ferments over several hours. At this time, the mixture in the fermentation section 40 is circulated between the mixing device 20 at, for example, 10% by mass per minute.

When the mixture is fermenting in the fermentation section 40, a direct current flows through the positive electrode 32 and the negative electrode 34 to the mixture. As a direct current voltage at this time, 1.0-4.0V is preferable and 1.2-3.0V are more preferable from a viewpoint of preventing the activity inhibition of lactic acid bacteria by the free hydrochloric acid ion etc. which are produced by an electrode. According to this, the lactic acid produced by the fermentation is moved to the electrode direction (direction of arrow A in FIG. 1) by the electropenetrating action, and is stored in the concentrating unit 38 through the partition 36. At this time, the water also moves to the concentrating unit 38, but since the movement speed of the lactic acid is faster, the lactic acid is concentrated. In addition, when a certain amount of fermentation waste accumulates in the fermentation part 40, fermentation waste is discharged | emitted from the discharge port not shown in figure.

The highly concentrated heritage stored in the concentrating unit 38 is circulated between the lactic acid storage tank 50 and further concentrated, whereby the highly concentrated heritage can be obtained from the lactic acid discharge pipe 52. In addition, the circulation of the highly concentrated heritage may be provided with a concentration sensor to discharge the lactic acid when the concentration is higher than or equal to a certain concentration, or may be discharged after the circulating for a certain period of time.

Next, the specific aspect of the fermentation tank used for the lactic acid production apparatus of this invention is demonstrated using FIG. 2 and FIG. 2 is a cross-sectional view for explaining a specific aspect of the fermenter according to the present invention, Figure 3 is an explanatory view for explaining a specific aspect of the fermenter according to the present invention.

As shown in Figure 2, the fermentation tank according to the present invention can be formed in a tubular shape. In addition, as shown in FIG. 3, a cylindrical cathode 62 is provided inside the normal fermentation tank 60 along the inner wall. Moreover, a cylindrical anode partition 64 having a mesh structure is provided on the inner side thereof. It is provided. 2 and 3, the space surrounded by the cathode 62 and the anode partition 64 becomes the concentrating portion 66, and the space surrounded by the anode partition only becomes the fermentation portion 68. As shown in Figs.

Further, the raw material fermentation tank 60 is further provided with a raw material supply port 70 and a circulating fluid supply port 72. The raw material supply port 70 is connected to the fermentation unit 68 and is configured to introduce a raw material (mixture) into the fermentation unit 68. In addition, the mixture in the fermentation unit 68 is discharged from the raw material outlet 74 at a constant rate to be returned to the mixing device 20 in FIG. Thus, corn starch or the like that has not contributed to the reaction in the fermentation unit 68 can be reused by incorporating it into the mixture. In addition, the purified liquid supply port 72 is installed in order to circulate the high concentration heritage between the lactic acid storage tank 50 and the concentrator 66 in Figure 1, the high concentration heritage supplied from the circulating fluid supply port 72 is newly Along with the lactic acid moved from the fermentation section 68 to the concentration section 66, it is sent from the lactic acid discharge port 76 to the lactic acid storage tank 50 in FIG.

In the conventional fermentation tank 60, the lactic acid produced by fermentation of cornstarch and lactic acid bacteria in the fermentation section 68 in the cylindrical anode partition 64 is mixed in the cathode 62 and the anode partition 64 in the mixture containing them. If a direct current flows, it moves from the fermentation section 68 to the concentrating section 66. Thus, lactic acid can be separated from the mixture. In this manner, the fermentation tank has a tubular shape, whereby efficient lactic acid separation and concentration can be performed.

In addition, although the aspect which uses only one fermentation tank was mentioned above, this invention is not limited to the structure, The some fermentation tank may be continuous.

<Polymerization process>

Next, the polylactic acid production apparatus of the present invention will be described with reference to Figs. Figure 4 is a schematic diagram conceptually showing the configuration of the polylactic acid production apparatus of the present invention. As shown in FIG. 4, the polylactic acid production device 80 of the present invention includes a mixing device 82, a polymerization tank 90, and an electric dehydration tank 100. The polylactic acid production device 80 mixes the catalyst with the lactic acid in the mixing device 82, heats the mixture in the polymerization tank 90, and dehydrates and condensates the polymerization mixture, and then, in the electric dehydration tank 100, By dehydration by promoting dehydration polymerization reaction of the lactic acid polymer, the desired polylactic acid can be obtained. In the polylactic acid production apparatus 80 of the present invention, the polymerization tank 90 and the electric dehydration tank 100 are connected to the circulation pipe 116, and have a desired molecular weight by repeating a predetermined number of times, time, polymerization and drying. Polylactic acid can be obtained.

Although the mixing apparatus 82 is not specifically limited, It is a field provided with well-known mixing means, such as a stirrer. In this mixing device 82, lactic acid and a catalyst are supplied. At this time, the mixing ratio (mass ratio q: w) of lactic acid (q) and catalyst (w) in the mixture is preferably from 100: 1 to 100: 10, more preferably from 100: 3 to 100: 5. As the catalyst, any catalyst can be used without particular limitation as long as it is a catalyst used for decondensation polymerization of lactic acid. For example, a mixture of ruthenium oxide and titanium oxide in a mass ratio of 50% by mass is preferable. In addition, the weight average volume particle diameter of the catalyst is preferably about 0.1 to 1um. The mixing device 82 mixes the supplied lactic acid and the catalyst and introduces the mixture into the polymerization tank 90 as a mixture.

The polymerization tank 90 performs deshrinkment polymerization by heating a mixture of the lactic acid and the catalyst supplied from the mixing device 82. In the polymerization tank 90, the lactic acid may be converted into a polylactic acid having a desired molecular weight through a two-step lactic polymerization process. The first lactic acid polymerization step is a step of synthesizing the oligomer from the lactic acid, and the heating temperature at this time is preferably about 110 to 160 ° C, more preferably about 130 to 150 ° C. The second lactic acid copolymerization step is a step of linking oligomers to synthesize a polylactic acid having a desired molecular weight, and the heating temperature at this time is about 110 to 140 ° C, more preferably about 115 to 120 ° C.

Moreover, it is preferable that the polymerization tank 90 heats lactic acid and advances a polymerization reaction, stirring using stirring means, in order to improve superposition | polymerization efficiency, as mentioned later.

The polymerization tank (90) is a lactic acid polymer discharge pipe (92) for supplying a dehydration-polymerized lactic acid polymer (including oligomer or polylactic acid or water that has not reached the desired molecular weight) to the electric dehydration tank (100). ) Is installed.

At least one pair of electrodes composed of the anode 102 and the cathode 104 is built in the electric dehydration tank 100, and these electrodes are connected to a power source (not shown). In addition, the inside of the tank of the electric dehydration tank 100 is divided into partitions 106 so as to be spaced between the anode 102 and the cathode 104, and the cathode 104 is provided on the partition 106. The dehydration part 108 is provided in the side which is present, and the dehydration part 110 is provided in the side in which the anode 102 is provided. The mixture supplied from the polymerization tank 90 is introduced into the dehydration unit 110.

The positive electrode 102 and the negative electrode 104 are preferably made of a precious metal such as platinum (Pt), and may be used by plating platinum on titanium or by depositing rutin on this surface. Can be. The positive electrode 102 and the negative electrode 104 are connected to a power source (not shown), and by supplying a current from the power source, it is possible to flow a DC current to the lactic acid polymer in the dewatering part 110. As described above, when a direct current flows through the lactic acid polymer in the dewatering part 110, the water contained in the lactic acid polymer flows from the positive electrode 102 side to the negative electrode 104 side by the electropenetrating action (arrow B in FIG. 4). Can be moved to).

The partition 106 may have any structure as long as water in the mixture can pass therethrough and can prevent passage of solids such as polylactic acid. For example, the partition wall 106 can have a mesh shape. Moreover, as a material which comprises the partition 36, as long as it has a certain tolerance to lactic acid etc., it can use without a restriction | limiting in particular. It is also possible to form the partition wall 106 itself with a metal constituting the anode 102 and to make the partition wall 36 itself the anode 102. In this case, the space where the space | interval from the dehydration part 108 is spaced by the partition 106 turns into a to-be-detachment part. Moreover, a polyimide film etc. can also be utilized suitably.

The dehydration part 108 is formed by partitioning the inside of the electric dehydration tank 100 by the partition wall 106, and is provided in the side in which the negative electrode 104 of the electric dehydration tank 100 is provided. The dehydration part 108 is connected with the glycerin supply pipe 112 and the glycerin discharge pipe 114, and is comprised so that glycerin may circulate in the dehydration part 108. As shown in FIG. Water moved from the dehydration unit 110 to the dehydration unit 108 is absorbed by anhydrous glycerin and discharged from the dehydration unit 108 as hydrous glycerin. The hydrous glycerin discharged from the dehydration unit 108 is removed from water by a known means such as distillation under reduced pressure, and reused as anhydrous glycerin.

One end of the circulation pipe 116 is connected to the dewatering part 110 of the electric dehydration tank 100. In addition, the other end of the circulation pipe 116 is connected to the polymerization tank 90, and between the polymerization tank 90 and the electric dehydration tank 100 until the polylactic acid in the dewatering part 110 reaches a desired molecular weight. It is configured to circulate. In addition, the dehydration part 110 is provided with the discharge port which abbreviate | omits illustration and is comprised so that the polylactic acid which reached | attained the desired molecular weight can be discharged other than measures. Here, the said discharge port may be provided in the polymerization tank. Although it does not specifically limit as a material which comprises the polymerization tank 90 and the electric dehydration tank 100, It is preferable that it is titanium (Ti) from a viewpoint of anti-glare property.

The flow of polylactic acid production in the polylactic acid production apparatus of the present invention will be described. First, the lactic acid and the catalyst are supplied to the mixing device 82 and mixed, and then introduced into the blood dewatering unit 110 of the electric dehydration tank 100. The lactic acid introduced into the dewatering part 110 is deshrunk-polymerized in the polymerization tank 90, and then dehydrated in the electric dehydration tank 100, and the desired poly by repeating such a process for a desired number of times or for a predetermined time. You can get a legacy. The number of times and the time for repeating such a step can be appropriately set in consideration of the molecular weight of the target polylactic acid. At this time, between the polymerization tank 90 and the electric dehydration tank 100, it is circulated by 10 mass% per minute, for example.

The temperature in the polymerization tank 90 is different in the first lactic acid polymerization step and the second lactic acid polymerization step. At this time, it is possible to change the temperature in the polymerization tank 90 in accordance with a predetermined number of times and time. Moreover, in this invention, it is preferable to go through the process of evaporating the water in lactic acid about 110-120 degreeC, before performing a 1st lactic acid polymerization process.

In the electric dehydration tank 100, a direct current flows through the positive electrode 102 and the negative electrode 104 to the lactic acid polymer. As a DC voltage at this time, about 3.0-6.0V are preferable and about 4.0-5.0V are more preferable. In this way, the water generated by the polymerization reaction of lactic acid moves in the current direction (direction of arrow B in FIG. 4) by the electropenetrating action, and passes through the partition wall 106 to the dewatering part 108. do. In addition, the polylactic acid synthesized to the desired molecular weight can be obtained by circulating between the desired number of times or time and the polymerization tank 90 and the electric dehydration tank.

Next, the specific aspect of the polymerization tank and the electric dehydration tank used for the polylactic acid production apparatus of this invention is demonstrated using FIG. 5 is a cross-sectional view for explaining a specific embodiment of the polymerization tank and the electric dehydration tank according to the present invention.

As shown in FIG. 5, the ordinary polymerization tank 120 has an inside side of the hollow cylinder (hollow gas) 124 in which the lactic acid supply unit 122 is installed, and the other side (that is, the lactic acid supply unit 122) is installed. , Lactic acid polymer outlet on the other side (screw tip side) of the cylinder 124 in which the screw (rod-shaped rotating body: 126) which has a spiral groove toward the screw tip side is built-in, and is not provided with the lactic acid supply part 122 128 is provided, and by rotating the screw 126, the lactic acid polymer outlet 128 can be transported while stirring and heating the lactic acid. The lactic acid polymer discharged from the lactic acid polymer outlet 128 is introduced into the electric dehydration tank 150. In addition, a motor (driving means: 130) is installed on the side where the lactic acid supply part 122 of the screw 126 is installed, and the screw 126 is provided with a motor having a gear gear having a driving gear and a driven gear (not shown). It is connected to the 130 and is rotatable by receiving electric power from a power source (not shown).

As the screw 126 rotates in the cylinder, the supplied lactic acid is deshrunk-polymerized at a temperature corresponding to the first and second lactic acid polymerization processes. On the outer side of the cylinder 124, an electric heater 132 for heating the inside through the cylinder wall is provided so as to cover the cylinder circumference, and the inside of the cylinder is heated evenly.

In addition, the conventional polymerization tank 120 is provided with a lactic acid polymer inlet 143 through which the lactic acid polymer dehydrated in the electric dehydration tank 150 is introduced, and the polylactic acid circulates with the electric dehydration tank 150. It is configured to be possible.

In FIG. 5, the electric dehydration tank 150 is communicated with the ordinary polymerization tank 120 through a pipe connected to the lactic acid polymer outlet 128. As shown in FIG. 5, the electric dehydration tank 150 has a cylindrical body 156 having a lactic acid polymer supply port 152 at one end and a dehydration outlet 154 at the other end, and a cylindrical body 156. ) So that the cylindrical normal polyimide film 158 provided inside of the &lt; RTI ID = 0.0 &gt; and &lt; / RTI &gt; and the shaft center parallel to the insertion direction (arrow direction C in Fig. 4) in the interior of the ordinary polyimide film 158 are rotated alternately. The twisted wing is composed of a static mixer 160 disposed adjacent to three stages, and the reverse polymer is reversely kneaded in order while inserting the lactic acid polymer supplied from the lactic acid polymer supply port 152 to perform dehydration treatment. have. In addition, the wall surface of the cylindrical body 156 is comprised from titanium (Ti).

Normally, the polyimide membrane 158 provided inside the cylindrical body 156 has a fine mesh structure of eye, and allows only the lactic acid polymer and water in water to permeate. The inside of the cylindrical body 156 is normally a polyimide film 158 as a boundary, and the inside of the polyimide film is usually a dewatering part 162, and the dehydrating part 164 is usually formed outside the polyimide film 158. Formed.

In addition, the wall surface of the cylindrical body 156 is provided with a glycerin supply port 166 for supplying anhydrous glycerin to the dewatering part 164 and a glycerin outlet 165 for discharging the hydrous glycerin inside the dewatering part. It is comprised so that glycerin may circulate in the dehydration part 164.

In the electric dehydration tank 150, a power source (not shown) is connected to the wall surfaces of the static mixer 160 and the cylindrical body 156, respectively. The static mixer 160 constitutes the anode electrode, and the cylindrical body 156 is connected. ) Constitutes the cathode electrode. For this reason, when an electric current flows in the mixture introduce | transduced from the normal polymerization tank 120, the water dissociated from the lactic acid polymer moves by the electrophoretic action from the inner side of the cylindrical body 156 to the outer side. Water moved from the inside of the cylindrical body 156 to the outside passes through the polyimide film 158 and moves to the dehydrating portion 164. Anhydrous glycerin is supplied to the dehydration part 164, and the water which has permeated the polyimide membrane 158 is normally absorbed by the anhydrous glycerin, and is discharged out of the electric dehydration tank 150 as a hydrous glycerin. The hydrous glycerin discharged out of the electric dehydration tank 150 is otherwise removed with water by suitable means such as distillation under reduced pressure, and supplied again from the glycerin supply port 166 as anhydrous glycerin.

The static mixer 160 serving as the anode electrode of the electric dehydration tank 150, for example, plated platinum (Pt) with titanium (Ti) as shown in Fig. 6, and further added rutin (Ru) on the surface thereof. The twisted blades 160a to 160c, which have been twisted to the left or to the right (for example, a twist angle of 90 °), have a three-stage adjacent configuration. The static mixer 160 is adapted to rotate in accordance with the twisted direction in response to the fluid pressure in the arrow direction C when the lactic acid polymer is inserted into the cylindrical body 156. By providing the static mixer 160 having such a structure in the electric dehydration tank 150, the moisture in the lactic acid polymer is easily in contact with the positive electrode, and it is possible to efficiently exhibit the electropenetrating action, and the dehydration efficiency of the lactic acid polymer Can increase.

In addition, the lactic acid polymer dehydrated in the electric dehydration tank 150 can be circulated between the normal polymerization tank 120 and the electric dehydration tank 150 until it reaches a desired molecular weight such as a desired number of times or times. The lactic acid polymer dehydrated in the electric dehydration tank 150 is discharged from the dehydration outlet 154 and again introduced into the ordinary polymerization tank 120.

The lactic acid polymer circulated between the number of times or the time set in advance so as to have a desired molecular weight, the ordinary polymerization tank 120 and the electric dehydration tank 150 is a polylactic acid having a desired molecular weight, and the polylactic acid of the ordinary polymerization tank 120 is Ejected from the outlet 136. Thus, using the polylactic acid polymerization apparatus of the present invention, it is possible to produce a polylactic acid having a desired molecular weight in about half the time with low energy compared with the case of using the conventional vacuum dehydration method. That is, the synthesis of polylactic acid having a desired molecular weight can be performed in a short time and low energy, and a polylactic acid having sufficient molecular weight can be obtained with high efficiency and short time.

As described above, according to the polylactic acid production apparatus of the present invention, it is also possible to continuously carry out everything from the generation of lactic acid to the polymerization of the polylactic acid, and the size of the equipment can be reduced, the cost can be reduced, the operation can be simplified, and the production cost can be reduced. It becomes possible. In addition, in the above, although only one polymerization tank and one electric dehydration tank were used, the present invention is not limited to this configuration, and a plurality of polymerization tanks and an electric dehydration tank may be connected.

Example

Hereinafter, the present invention will be described more specifically in Examples. However, this invention is not limited to this.

Example 1

1. Creation of a legacy

The lactic acid was produced using the lactic acid production apparatus having a conventional fermentation tank shown in FIGS. 2 and 3 in the following order.

(1) Preparation of raw material suspension

Corn starch (30 mass parts), salt (0.5 mass part), and water (69.5 mass part) were stirred at 150 rpm for 5 minutes using the mixing apparatus, and the raw material suspension was prepared.

(2) Preparation of liquefied starch

The raw material suspension obtained above was steamed at 95 degreeC for 15 minutes, and gelatinized starch was prepared. The resulting gelatinized starch (99.4 parts by mass), calcium carbonate (0.5 parts by mass) and starch liquor (trade name: Congen T, manufactured by Converse Chemical Co., Ltd.) (0.1 parts by mass) were prepared by pH in acetic acid (Ph = 6 to 7). ), The mixture was stirred at 30 rpm for 10 minutes at a temperature of 90 ° C. The resulting mixture was left to stand for 60 minutes at a temperature of 90 ° C. and pH 6-7 to prepare liquefied starch.

(3) Preparation of Saccharified Starch

After cooling the liquefied starch (99.9 parts by mass) obtained above to 70 ° C or less, starch branched enzyme (trade name: PLICE, manufactured by Greister, Co., Ltd.) (0.1 parts by mass) is added, and the pH is increased in acetic acid. After the preparation (pH = 5 to 6), the mixture was stirred at 50 rpm for 10 minutes at a temperature of 65 ° C. The resulting mixture was left to stand at a temperature of 65 ° C. and pH 5 to 6 for another 60 minutes to prepare saccharified starch.

* (4) generation of heritage

After cooling the saccharified starch (99.9 mass parts) obtained above to 45 degreeC or less, lactic acid bacteria (0.1 mass part) was added, and it stirred at the temperature of 45 degreeC for 10 minutes by 150 rpm by the mixing apparatus A. At this time, the pH of the mixture was 5-6.

The resulting mixture was introduced into the fermenter shown in FIGS. 2 and 3. Fermentation was carried out while flowing a direct current, and 20% by mass of lactic acid was obtained. At this time, the fermentation conditions were: temperature: 40 degreeC, pH: 5-6, reaction time 240 minutes, electric permeation voltage: DC 2.4V. In addition, the mixture circulated between the fermenter and the mixing apparatus A at 10 mass% every minute.

<< evaluation >>

1 g of lactic acid bacteria was added to 1 kg of saccharified starch obtained under the same conditions as described above 1, and measured for the relationship between the voltage added between the electropenetrating electrodes and the concentration of lactic acid produced at 40 ° C. using the same fermenter as in Example 1. . At this time, the electric penetration voltage was measured as 0 V, 1.2 V, 2.4 V, and 3.6 V, respectively. The results are shown in FIG.

7 is a graph showing the relationship between lactic acid concentration and electric penetration voltage. As can be seen from FIG. 7, when no current was flowed between the electrodes (0 V), the lactic acid concentration did not become 5.6 mass% or less, but when the electric penetration voltage was changed to 1.2 V, 16.3 after 8 hours. The concentration improved to mass%. In addition, when the electrical penetration voltage was changed to 2.4 V, the lactic acid concentration after 8 hours was improved to 24.5 mass%. On the other hand, when the electrical penetration voltage was changed to 3.6 V, the concentration of lactic acid obtained was about 14 mass%. As a result, it turns out that between 1.2-3.0V is preferable as said electric penetration voltage.

2. Synthesis of Polylactic Acid

Lactic acid was produced using the conventional polymerization tank and electric dehydration tank shown in FIG. 5 according to the following procedure.

(1) drying process

As described above, 99.5 parts by mass of lactic acid having a concentration of 20% and 0.5 parts by mass of catalyst (mixed with rutin oxide and titanium oxide at a mass ratio of 50% by mass) were stirred at 150 rpm for 10 minutes using a mixing apparatus. At this time, pH of the mixture was about 3.5-4, and the temperature was 90 degreeC. Next, the resulting mixture was evaporated to dryness at 110 to 120 ° C. for 0.5 hour. At this time, the density | concentration of lactic acid was about 60 mass%.

(2) polymerization, dehydration process

The mixture of the resulting lactic acid and the catalyst was polymerized and dehydrated for 240 minutes while circulating between the mixing tank and the electric dehydration tank at 10 mass% per minute using the polymerization tank and the electric dehydration tank shown in FIG. 5. At this time, in the electric dehydration tank, a direct current was passed through the polylactic acid at an electric transmission voltage of 4.5 V between the electrodes, and dehydration was performed. In addition, the temperature of the mixing tank was made into 140-145 degreeC for the first 90 minutes, and made the remaining 150 minutes into 115-120 degreeC. The mass average molecular weight of the resulting polylactic acid was measured by DSC and found to be 120,000.

<< evaluation >>

In the polymerization and dehydration step of lactic acid, the method according to the present invention using the same method as described above (initial lactic acid temperature: 60% by mass, electric permeation voltage 4.8V, endpoint polylactic acid mass molecular weight: 120,000, polymerization tank shown in Fig. 5). And an electric dehydration tank) and the conventional vacuum dehydration method described in Japanese Patent Laid-Open No. 2003-335850 (initial lactic acid concentration: 60% by mass, vacuum degree: 0.08 (MPa), end point polylactic acid weight). Average molecular weight: 120,000). The results are shown in FIG. 8 is a graph showing the relationship between polymerization temperature and polymerization time for the polymerization reaction of polylactic acid.

As can be seen from FIG. 8, when polymerization and dehydration were carried out by the method according to the present invention using an electropenetrating dehydration tank, the time T1 ′ required for the first lactic polymerization process is about 20 minutes, Since the time T2 'required for the second lactic acid polymerization step was about 160 minutes, the polylactic acid having a weight average molecular weight of 120,000 was obtained in about 240 minutes including the dry evaporation step.

On the other hand, when polymerization and dehydration are carried out using a conventional method using a vacuum dehydration method, the time T1 required for the first lactic acid polymerization step is about 30 minutes and the time required for the second lactic acid polymerization step ( Since T2) was about 390 minutes, it took 480 minutes to obtain a polylactic acid having a weight average molecular weight of 120,000, including a dry evaporation step. For this reason, the polymerization time of this invention using the electropenetrating dehydration tank of this invention was able to obtain the polylactic acid which has a desired molecular weight in about half the time compared with the case of using the conventional vacuum dehydration method.

As can be seen from FIG. 8, when the method of the present invention is used, the polymerization temperature required in the first lactic acid polymerization step (T1 ') is equal to 137 ° C and the second lactic acid polymerization step (T2'). Since the polymerization temperature was 118 ° C, the polymerization temperature required for the first lactic acid polymerization step (T1) was 145 ° C, and the polymerization temperature required for the second lactic acid polymerization step (T2) was 123 ° C. It was found that the polymerization temperature can be lowered by about 4 to 6% than in the case of using the reduced pressure dehydration method of.

As described above, according to the present invention, a method for producing a polylactic acid capable of obtaining a polylactic acid having a desired molecular weight in a high efficiency and a short time, a lactic acid production apparatus capable of obtaining a high concentration of a lactic acid in a high efficiency, and a sufficient molecular weight in a high efficiency and a short time It is possible to provide a polylactic acid production apparatus capable of obtaining a polylactic acid having.

In addition, by using the method for producing a polylactic acid, a lactic acid production device, and a polylactic acid production device of the present invention, it is possible to continuously carry out the production of lactic acid to the polymerization of polylactic acid, and further, the equipment can be downsized, reduced in price, and operated. It is also possible to simplify the manufacturing process and reduce the manufacturing cost.

Claims (9)

A polymerization process of synthesizing a lactic acid polymer by heating and dehydrating polymerization of the lactic acid, A direct current is applied to the lactic acid polymer polymerized in the polymerization step in an electric dehydration tank having at least a pair of electrodes, a partition wall, and a dewatering part separated by the partition wall, and wherein the dewatering part is provided on the cathode side of the electrode. Electrodehydration process to move the water in the lactic acid polymer to the dewatering part by electropenetration Method for producing a polylactic acid, characterized in that it comprises a. Lactic acid introduction means to introduce a legacy; Polymerization means for heating and derivatizing the lactic acid introduced from the lactic acid introduction means; At least one pair of electrodes, a partition wall, and a dewatering portion divided by the partition wall, and the dewatering portion includes electrical dehydration means provided at a cathode side of the electrode, The electrode dehydration means is a polylactic acid production apparatus characterized in that the direct current flows to the lactic acid polymer dehydrating and condensation polymerization in the polymerization means, and the water in the lactic acid polymer is moved to the dewatering part by electroinfiltration. The method of claim 2, A fermentation concentrating means having a raw material introduction means for introducing lactic acid bacteria and a fermentation tank, the fermentation tank having a condensation unit provided at a cathode side of the electrode and separated by at least one pair of electrodes, a partition wall, and the partition wall; The fermentation concentrating means flows a direct current to the lactic acid obtained by fermenting the vegetable starch and lactic acid bacteria introduced from the raw material introduction means in the fermentation tank, and moves to the concentrating unit by electroporation, and stores the lactic acid in the concentrating unit. , The lactic acid production apparatus characterized in that for supplying the lactic acid stored in the concentration unit to the polymerization means. The method of claim 3, The fermentation concentrating means includes a discharge pipe for discharging the lactic acid stored in the concentrating unit, a lactic acid storage tank for supplying the lactic acid discharged from the discharge pipe and storing the lactic acid, and supplying the lactic acid in the lactic acid storage tank to the concentrating unit. And a supply means for supplying said lactic acid in said lactic acid storage tank to said polymerization means. The method of claim 4, wherein The polymerization means includes a hollow gas having openings at both ends and supplied with lactic acid from an opening in one direction, a rod-shaped rotating body embedded in the hollow gas, having a spiral groove, and an interior of the hollow gas. And heating means for heating the And rotating the rod-shaped rotating body to compress the lactic acid by heating and compressing the lactic acid from the opening in one direction toward the opening in the other direction. The method according to any one of claims 2 to 5, The electric dewatering means includes a hollow body through which the lactic acid is inserted, and a plurality of rotary blades disposed inside the hollow body and adjacently disposed so as to reversely rotate with each other, with the insertion direction of the lactic acid as the rotation axis. Polylactic acid production apparatus. The method of claim 6, And said rotary blade constitutes an anode of said electrode in said electric dehydration means. The method according to any one of claims 3 to 5 or 7, Lactic acid production apparatus characterized in that the plant starch is corn starch. The method of claim 6, Lactic acid production apparatus characterized in that the plant starch is corn starch.

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