JP2023166063A - Method for producing polylactic acid, device for producing polylactic acid, method for producing biodegradable plastic, and device for producing biodegradable plastic - Google Patents

Abstract

To provide a method for producing polylactic acid which can yield polylactic acid of uniform quality within a shortened production time frame, a device for producing polylactic acid, a method for producing biodegradable plastic, and a device for producing biodegradable plastic.SOLUTION: A primary fermentation tank 12 encloses plant-derived materials for lactic acid fermentation. First separation means 13 separates a fermented product, fermented in the primary fermentation tank 12, into a liquid part and a solid part. A secondary fermentation tank 15 encloses the liquid part of the fermented product separated by the first separation means 13, allowing it to undergo re-fermentation. Second separation means 16 separates the re-fermented product, re-fermented in the secondary fermentation tank 15, into a liquid part and a solid part. Dehumidification means 17 evaporates water from the liquid part of the re-fermented product separated by the second separation means 16, extracting lactic acid. Polymerization means 18 heats lactic acid extracted by the dehumidification means 17, and polymerizing it to yield polylactic acid 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing polylactic acid, an apparatus for producing polylactic acid, a method for producing biodegradable plastic, and an apparatus for producing biodegradable plastic.

A conventional method for producing polylactic acid from plant-based raw materials involves lactic acid fermentation of plant-based raw materials for a predetermined period of time, and producing polylactic acid using the obtained lactic acid as a raw material (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2006-262770

In the conventional method for producing polylactic acid as described in Patent Document 1, lactic acid fermentation is performed in one stage over a predetermined period, so the pH after fermentation is not stable and the quality of the produced polylactic acid becomes uneven. There was a problem. Furthermore, since it takes about one month at the earliest to produce polylactic acid, it is desired to shorten the production period.

The present invention has been made with attention to such problems, and provides a polylactic acid manufacturing method, a polylactic acid manufacturing apparatus, and a polylactic acid manufacturing method that can obtain polylactic acid of uniform quality and shorten the manufacturing period. The present invention aims to provide a method for producing degradable plastics and an apparatus for producing biodegradable plastics.

In order to achieve the above object, the method for producing polylactic acid according to the present invention includes a first fermentation step in which a plant-based raw material is hermetically sealed and fermented with lactic acid, and a fermented product in the first fermentation step is divided into a liquid part and a solid part. a first separation step in which the liquid part of the fermented product separated in the first separation step is sealed and re-fermented; and a second fermentation step in which the re-fermented product in the second fermentation step is separated into a liquid and a dehumidification step of evaporating water to extract lactic acid from the liquid portion of the re-fermented product separated in the second separation step; and a polymerization step of heating and polymerizing the lactic acid to obtain polylactic acid.

The polylactic acid production apparatus according to the present invention includes a primary fermentation tank in which a plant-based raw material is sealed and fermented with lactic acid, and a first separation in which the fermented product fermented in the primary fermentation tank is separated into a liquid part and a solid part. a secondary fermentation tank for sealing and re-fermenting the liquid part of the fermented product separated by the first separating means; and a secondary fermentation tank for re-fermenting the re-fermented product re-fermented in the secondary fermentation tank into a liquid part and a solid part. a second separation means for separating the liquid part of the re-fermented product separated by the second separation means, a dehumidification means for extracting lactic acid by evaporating water from the liquid part of the re-fermented product separated by the second separation means, and heating the lactic acid extracted by the dehumidification means. and polymerization means for obtaining polylactic acid.

According to the apparatus for producing polylactic acid according to the present invention, the method for producing polylactic acid according to the present invention can be easily carried out. The method for producing polylactic acid and the apparatus for producing polylactic acid according to the present invention include re-fermenting the liquid part of the fermented product that has been subjected to lactic acid fermentation in the first fermentation process or the first fermentation tank in the second fermentation process or the second fermentation tank. By doing so, the pH after re-fermentation can be stabilized. By using the liquid part of the re-fermented product with stable pH, polylactic acid of uniform quality can be obtained. In addition, by performing fermentation of plant-based raw materials in two stages: the first fermentation process or first fermentation tank, and the second fermentation process or second fermentation tank, the fermentation period is shorter than when fermentation is performed in one stage. Therefore, the production period for polylactic acid can be shortened.

In the method for producing polylactic acid and the apparatus for producing polylactic acid according to the present invention, the plant-based raw material is preferably made of a raw material plant that has been pretreated. Plant-based raw materials include, for example, pulverized raw material plants, raw material plants that have been heated and stirred with water, and raw material plants that have been cut into pieces. Further, sugar content of about 2 to 10% by weight may be added as necessary. In the first fermentation step or the first fermentation tank, lactic acids and other raw materials may be added to the plant-based raw material to perform lactic acid fermentation.

The method for producing polylactic acid and the apparatus for producing polylactic acid according to the present invention each produce a gas such as carbon dioxide generated in the first fermentation step or the first fermentation tank, and the second fermentation step or the second fermentation tank, for example. It may have a process or a tank for recycling carbon water as a raw material. The method also includes a step of producing fertilizer from a solid portion of the fermented product in the first separation step or the first fermentation tank and a solid portion of the re-fermented product in the second separation step or the second fermentation tank. You may do so.

In the method for producing polylactic acid according to the present invention, in the first fermentation step, the plant-based raw material is fermented in a sealed manner for 5 to 25 days, and in the second fermentation step, the pH of the liquid part of the fermented material is 2.2. The dehumidifying step includes the liquid part of the re-fermented product separated in the second separation step. On the other hand, it is preferable that water is atomized and evaporated by ultrasonic vibration, and in the polymerization step, the lactic acid is polymerized by heating at a temperature of 190 to 230° C. for 10 minutes to 1 hour. In this case, polylactic acid with more stable pH and quality can be obtained. Furthermore, polylactic acid can be efficiently obtained in a short period of about 2 to 4 weeks. Furthermore, in order to stabilize the quality of polylactic acid, the dehumidification step is preferably carried out at a temperature of 25 to 50°C for 5 to 6 hours.

In the method for producing polylactic acid according to the present invention, the plant-based raw material is at least one of white rice, brown rice, hulled rice, germinated rice, kelp, wakame, sargassum, egg shell, cycad fruit, shell of shell, or konjac potato. It is preferable to include one. When the plant-based raw material includes white rice, brown rice, unhulled rice, or germinated rice, rice-derived polylactic acid can be obtained. Furthermore, when the plant-based raw material contains brown seaweeds such as kelp, wakame, or sargassum, polylactic acid containing fucoidan and alginic acid can be obtained. Calcium-containing polylactic acid can be obtained when the plant-based raw materials include egg shells, cycad berries or shells. When the plant-based raw material contains konjac potatoes, sticky konjac-derived polylactic acid can be obtained.

In the method for producing rice-derived polylactic acid according to the present invention, a plant-based raw material containing at least one of white rice, brown rice, unhulled rice, or germinated rice is heated at 25 to 60°C, preferably at 25 to 60°C, so that the pH of the fermented product is 4 or less. A first fermentation step in which lactic acid fermentation is carried out in a sealed state at a temperature of 35 to 45°C for 5 to 10 days; a first separation step in which the fermented product in the first fermentation step is separated into a liquid part and a solid part; 1. A heating step of heating the liquid part of the fermented product separated in the separation step for 20 minutes to 1 hour at a temperature of 60 to 100°C to treat it with germs, and a liquid part of the fermented product that has been treated with germs in the heating step. a second fermentation step in which the liquid part of the fermented product is sealed and re-fermented at a temperature of 25 to 60 °C, preferably 35 to 45 °C, so that the pH of the part becomes 2.2 to 2.6; A second separation step of separating the re-fermented product from the second fermentation step into a liquid part and a solid part, and evaporating water from the liquid part of the re-fermented product separated in the second separation step to extract lactic acid. It is characterized by comprising a dehumidification step and a polymerization step of heating the lactic acid extracted in the dehumidification step at a temperature of 190 to 230° C. for 10 minutes to 1 hour to polymerize it to obtain polylactic acid.

The method for producing rice-derived polylactic acid according to the present invention adds a heating step to the method for producing polylactic acid according to the present invention, and it is possible to obtain rice-derived polylactic acid with a stable pH and uniform quality. can. Furthermore, rice-derived polylactic acid can be efficiently obtained in a short period of about two weeks. It is hygienic because germs are removed during the heating process. In addition, in the dehumidifying step, water may be atomized and evaporated by ultrasonic vibration to the liquid portion of the re-fermented product separated in the second separation step.

The apparatus for producing polylactic acid according to the present invention further includes a heating means for heating the liquid part of the fermented product separated by the first separating means to treat it with germs, and the plant-based raw material is white rice, brown rice, etc. , unhulled rice, or germinated rice, and the secondary fermentation tank may be configured to seal and re-ferment the liquid portion of the fermented product that has been treated with germs by the heating means. In this case, the method for producing rice-derived polylactic acid according to the present invention can be easily carried out using the apparatus for producing polylactic acid according to the present invention.

The method for producing polylactic acid for a binder according to the present invention includes adding rice according to the present invention to a plant-based raw material containing at least one of kelp, wakame, sargassum, egg shell, cycad fruit, shellfish, or konnyaku potato. A first fermentation step in which the rice-derived polylactic acid produced by the method for producing rice-derived polylactic acid is added, sealed for 10 to 25 days, and lactic acid fermented, and the fermented product in the first fermentation step is separated into a liquid part and a solid part. and a first separation step in which the liquid portion of the fermented product is separated at pH 2.2 to 2.6. a second fermentation step in which the fermented product is re-fermented in a sealed state at a temperature of preferably 35 to 45 °C; a second separation step in which the re-fermented product in the second fermentation step is separated into a liquid part and a solid part; a dehumidifying step of evaporating water to extract lactic acid from the liquid part of the re-fermented product separated in the second separation step; It is characterized by having a polymerization step of heating and polymerizing for a period of time to obtain polylactic acid.

The method for producing polylactic acid for a binder according to the present invention utilizes the method for producing polylactic acid for use as a binder according to the present invention, and can obtain polylactic acid for a binder having a stable pH and uniform quality. When the plant-based raw materials include brown seaweeds such as kelp, wakame, or sargassum, polylactic acid for binders containing fucoidan and alginic acid can be obtained. When the plant-based raw materials include egg shells, cycad berries or shells, polylactic acid for the binder containing calcium can be obtained. When the plant-based raw material contains konjac potatoes, sticky konjac-derived polylactic acid for the binder can be obtained. In addition, in the dehumidifying step, water may be atomized and evaporated by ultrasonic vibration to the liquid portion of the re-fermented product separated in the second separation step.

The method for producing biodegradable plastics according to the present invention includes rice-derived polylactic acid obtained by the method for producing rice-derived polylactic acid according to the present invention, and rice-derived polylactic acid obtained by the method for producing polylactic acid for binders according to the present invention. a stirring step of mixing and stirring polylactic acid for the binder while heating; a raw material manufacturing step of removing water after mixing and stirring and polylactic-oxidizing the mixture; cooling the polylactic-oxidized mixture; A solidifying step of solidifying to obtain a biodegradable plastic is characterized.

A biodegradable plastic manufacturing apparatus according to the present invention includes: a polylactic acid manufacturing apparatus according to the present invention; a stirring means for mixing and stirring a plurality of types of polylactic acids obtained by the polylactic acid manufacturing apparatus while heating; A raw material producing means for removing water and polylactic-oxidizing the mixture after mixing and stirring by the stirring means, and cooling and solidifying the mixture polylactic-oxidized by the raw material producing means to produce a biodegradable plastic. and a solidification means for obtaining the solidification method.

According to the biodegradable plastic manufacturing apparatus according to the present invention, the biodegradable plastic manufacturing method according to the present invention can be easily carried out. In the biodegradable plastic manufacturing method and biodegradable plastic manufacturing apparatus according to the present invention, polylactic acid obtained from plant-based raw materials such as rice is used, so biodegradable plastic can be manufactured. . By mixing polylactic acid as a binder containing calcium in the stirring process, the resulting biodegradable plastic can be made harder. By mixing polylactic acid for a binder containing alginic acid in the stirring step, the adhesiveness increases and it becomes easier to form into any desired shape such as pellets. Moreover, flexibility can be added to the obtained biodegradable plastic, and the biodegradable plastic can be made difficult to break. By mixing polylactic acid for a binder derived from konjac potatoes in the stirring process, a highly viscous biodegradable plastic can be obtained.

In the method for producing a biodegradable plastic according to the present invention, the stirring step involves mixing and stirring the rice-derived polylactic acid and the binder polylactic acid while heating at a temperature of 190 to 230°C for 30 minutes to 1 hour. However, in the raw material manufacturing step, it is preferable that water is removed and the mixture is subjected to polylactic oxidation at a temperature of 70 to 90°C. In this case, biodegradable plastics with better performance can be obtained.

In the method for producing a biodegradable plastic according to the present invention, it is preferable that in the stirring step, the polylactic acid for the binder is mixed and stirred at a ratio of 5 to 30% by weight with respect to the rice-derived polylactic acid. In this case, biodegradable plastics with particularly high viscosity can be obtained.

According to the present invention, a method for producing polylactic acid, an apparatus for producing polylactic acid, a method for producing biodegradable plastic, and a biodegradable plastic that can obtain polylactic acid of uniform quality and shorten the production period. can provide manufacturing equipment.

1 is a block diagram showing an apparatus and method for producing polylactic acid according to an embodiment of the present invention. FIG. 1 is a block diagram showing a plasticizing device of a biodegradable plastic manufacturing device and manufacturing method according to an embodiment of the present invention.

Embodiments of the present invention will be described below based on the drawings.
1 and 2 show a method for producing polylactic acid, an apparatus for producing polylactic acid, a method for producing biodegradable plastic, and an apparatus for producing biodegradable plastic, according to embodiments of the present invention.
The biodegradable plastic production apparatus according to the embodiment of the present invention includes the polylactic acid production apparatus according to the embodiment of the present invention shown in FIG. 1 and the plasticization apparatus shown in FIG. 2.

As shown in FIG. 1, the polylactic acid production apparatus according to the embodiment of the present invention includes a pretreatment means 11, a primary fermentation tank 12, a first separation means 13, a heating means 14, a secondary fermentation tank 15, and a second fermentation tank 12. It has a separating means 16, a dehumidifying means 17, a polymerizing means 18, a gas treatment tank 19, and a fertilizer forming means 20.
As shown in FIG. 1, the pretreatment means 11 is configured to perform pretreatment on a plant 1 as a raw material to form a plant-based raw material. Specifically, when the raw material plant 1 includes polished rice, brown rice, unhulled rice, or germinated rice, the pretreatment means 11 adds water to the crushed raw material plant 1 or the raw material plant 1 and heats and stirs the raw material, It is made into a mushy state to form a plant-based raw material. Further, when the raw material plant 1 contains kelp, seaweed, sargassum, egg shell, cycad fruit, shell or konnyaku potato, the pretreatment means 11 cuts the raw material plant 1 into pieces to obtain the plant-based raw material. It is supposed to form. The pretreatment means 11 is configured to send the treated plant material to the primary fermentation tank 12.

The primary fermentation tank 12 consists of a closed tank equipped with a stirring device. The primary fermentation tank 12 is configured to store and seal the plant-based raw materials and additives such as lactic acid that have been treated by the pretreatment means 11, and to perform lactic acid fermentation while stirring. The primary fermentation tank 12 is configured to send the fermented product to the first separation means 13 and send gas components such as carbon dioxide generated during fermentation to the gas processing tank 19.

The first separation means 13 consists of a filtration device. The first separation means 13 is configured to filter the fermented product fermented in the primary fermentation tank 12 and separate it into a liquid part and a solid part. The first separation means 13 is configured to send the liquid part of the separated fermented product to the heating means 14 or the secondary fermentation tank 15, and send the solid part of the fermented product to the fertilizer means 20.

As shown in FIG. 1, the heating means 14 is composed of a heating device and is configured to be able to heat the liquid portion of the fermented product separated by the first separation means 13. Thereby, the heating means 14 is configured to treat the liquid portion of the fermented product with germs. The heating means 14 is configured to send the liquid portion of the heated fermented product to the secondary fermentation tank 15.

The secondary fermentation tank 15 consists of a closed tank equipped with a stirring device. The secondary fermentation tank 15 is configured to store and seal the liquid part of the fermented product heated by the heating means 14 or the liquid part of the fermented product separated by the first separation means 13, and re-ferment it while stirring. ing. The secondary fermentation tank 15 sends the re-fermented product to the second separation means 16 and sends gas components such as carbon dioxide generated during the re-fermentation to the gas processing tank 19.

The second separation means 16 consists of a filtration device. The second separation means 16 is configured to filter the re-fermented product re-fermented in the secondary fermentation tank 15 and separate it into a liquid part and a solid part. The second separating means 16 is configured to send the liquid part of the separated re-fermented product to the dehumidifying means 17 and send the solid part of the re-fermented product to the fertilizer means 20.

As shown in FIG. 1, the dehumidifying means 17 has a tank 17a equipped with an ultrasonic vibrator. The dehumidifying means 17 atomizes water into the liquid portion of the re-fermented product separated by the second separating means 16 using ultrasonic vibrations generated by an ultrasonic vibrator, and evaporates the water with a dehumidifying function. It is configured like this. Thereby, the dehumidifying means 17 can extract lactic acid from the liquid part of the re-fermented product. The dehumidifying means 17 is configured to send the extracted lactic acid to the polymerizing means 18.

The polymerization means 18 consists of a heating device and is configured to be able to heat the lactic acid extracted by the dehumidification means 17. Thereby, the polymerization means 18 polymerizes lactic acid to obtain polylactic acid 2. The polymerization means 18 is capable of discharging the obtained polylactic acid 2.

As shown in FIG. 1, the gas processing tank 19 is configured to collect and store gas such as carbon dioxide generated in the primary fermentation tank 12 and the secondary fermentation tank 15. The gas treatment tank 19 is configured to, for example, detoxify the collected gas and discharge it, or reuse the collected carbon dioxide as a raw material for carbon water.

The fertilizer forming means 20 is configured to be able to produce fertilizer from the solid part of the fermented product separated by the first separating means 13 and the solid part of the re-fermented product separated by the second separating means 16.

As shown in FIG. 2, the plasticization apparatus includes stirring means 21, raw material production means 22, and solidification means 23. The stirring means 21 consists of a tank equipped with an ultrasonic stirring function. The stirring means 21 is configured to store a plurality of types of polylactic acids 2 discharged from the polymerization means 18, and mix and stir them while heating them using an ultrasonic stirring function. The stirring means 21 is configured to send the mixture after mixing and stirring to the raw material manufacturing means 22.

The raw material manufacturing means 22 is comprised of a heating device, and is configured to heat the mixture mixed and stirred by the stirring means 21 to remove water, and to polylactic oxidize the mixture. The raw material production means 22 is configured to send the polylactic oxidized mixture to the solidification means 23.

The solidifying means 23 has a container made of silicon or clay, and is configured to store the polylactic-oxidized mixture in the raw material manufacturing means 22, cool it, and solidify it. Thereby, the solidifying means 23 obtains the biodegradable plastic 3. The solidifying means 23 is capable of discharging the obtained biodegradable plastic 3. Note that the container has any desired shape depending on the shape of the biodegradable plastic 3 to be manufactured.

According to the apparatus for producing polylactic acid according to the embodiment of the present invention, the method for producing polylactic acid according to the embodiment of the present invention can be easily carried out. Moreover, according to the biodegradable plastic production apparatus of the embodiment of the present invention, the biodegradable plastic production method of the embodiment of the present invention can be easily carried out.

[Manufacture of rice-derived polylactic acid]
In the method for producing polylactic acid according to the embodiment of the present invention, when the raw material plant 1 includes polished rice, brown rice, unhulled rice, or germinated rice, first, the pretreatment means 11 is used to crush the raw material plant 1 or the raw material. Add water to the plant and heat and stir to turn it into a mushy state to form a plant-based raw material. At this time, about 2 to 10% by weight of sugar may be added as necessary.

Next, the pretreated plant-based raw material is stored in the primary fermentation tank 12 and sealed, and is subjected to lactic acid fermentation while being maintained at a temperature of 25 to 60°C, preferably 35 to 45°C. At this time, since the starch of the plant 1 is decomposed by sugar, the growth of lactic acid bacteria can be promoted. During fermentation, carbon dioxide gas is generated and filled in the primary fermentation tank 12, so an appropriate amount of gas components are discharged into the gas treatment tank 19 at any time, and after the gas is discharged, the tank is sealed again and fermentation is continued. During fermentation, the pH of the fermented product is measured using a pH meter, and the fermentation is continued until the pH of the fermented product drops to 4 or less. Specifically, by fermenting for about one week, the pH decreases to 4 or less.

When the pH drops to 4 or less, the first separation means 13 separates the fermented product into a liquid part and a solid part. The liquid portion of the separated fermented product is heated by the heating means 14 at a temperature of 60 to 100° C. for about 30 minutes to treat it for germs. Note that the solid portion of the separated fermented product is sent to the fertilizer forming means 20 and reused as fertilizer. The liquid part of the fermented product heated by the heating means 14 is stored in the secondary fermentation tank 15 and sealed, and the pH of the fermented product is maintained at a temperature of 25 to 60°C, preferably 35 to 45°C. Ferment again until it reaches 2.2 to 2.6.

Precipitated starch is separated from the re-fermented product. This makes the water content of the re-fermented product transparent. This re-fermented product is separated into a liquid part and a solid part by the second separation means 16. The dehumidifying means 17 atomizes water to the liquid part of the separated re-fermented product at a temperature of 25 to 50° C. for 5 to 6 hours using ultrasonic vibrations of 2.4 MHz, and the dehumidifying function evaporates the water. let This allows lactic acid to be extracted. The extracted lactic acid is placed in an aluminum container and heated at a temperature of 190 to 230°C for 10 minutes to 1 hour to polymerize the lactic acid. Thereby, rice-derived polylactic acid 2a can be obtained. The number of lactic acid bacteria in the rice-derived polylactic acid 2a obtained was measured by the BCP agar medium method and was found to be 3,000,000 or more/ml (more than the upper limit of detection).

[Manufacture of polylactic acid for binder containing alginic acid]
In the method for producing polylactic acid according to the embodiment of the present invention, when the raw material plants 1 include brown seaweeds such as kelp, wakame, and sargassum, first, the raw material plants 1 are cut into small pieces by the pretreatment means 11. Powder is formed to form a plant-based material.

Next, the pretreated plant-based raw materials and rice-derived polylactic acid 2a are stored in the primary fermentation tank 12 and sealed, and kept at a temperature of 25 to 60°C, preferably 35 to 45°C. Let it ferment with lactic acid for about a week. At this time, the seaweeds are decomposed by lactic acid, and the alginic acid contained in the seaweeds dissolves onto the lactic acid, so that lactic acid containing alginic acid is formed. Further, during fermentation, carbon dioxide gas is generated and filled in the primary fermentation tank 12, so an appropriate amount of gas components are discharged into the gas processing tank 19 at any time, and after the gas is discharged, the tank is sealed again and fermentation continues.

After fermentation, the first separation means 13 separates the fermented product into a liquid part and a solid part. The liquid part of the separated fermented product is stored in the secondary fermentation tank 15, sealed tightly, and maintained at a temperature of 25 to 60°C, preferably 35 to 45°C, until the pH of the fermented product is 2.2 to 2. Ferment again until it reaches .6. At this time, since seaweed starch containing a large amount of alginic acid is decomposed by sugar, re-fermentation of lactic acid bacteria containing a large amount of alginic acid can be promoted. Note that the solid portion of the separated fermented product is sent to the fertilizer forming means 20 and reused as fertilizer.

Precipitated starch is separated from the re-fermented product to stabilize the water content of the re-fermented product. The stabilized re-fermented product is separated into a liquid part and a solid part by the second separation means 16. The dehumidifying means 17 atomizes water to the liquid part of the separated re-fermented product at a temperature of 25 to 50° C. for 5 to 6 hours using ultrasonic vibrations of 2.4 MHz, and the dehumidifying function evaporates the water. let This allows lactic acid to be extracted. The extracted lactic acid is placed in an aluminum container and heated at a temperature of 190 to 230°C for 10 minutes to 1 hour to polymerize the lactic acid. The polymerized lactic acid is placed in a silicone or clay container and cooled to solidify. Thereby, polylactic acid 2b for a binder containing alginic acid can be obtained. Furthermore, polylactic acid 2b for binder containing alginic acid also contains a large amount of fucoidan.

[Manufacture of polylactic acid for binder containing calcium]
In the method for producing polylactic acid according to the embodiment of the present invention, when the raw material plant 1 contains egg shells, cycad nuts, or shells, first, the raw material plant 1 is cut into small pieces by the pretreatment means 11. and powder to form a plant-based raw material.

Next, the pretreated plant-based raw materials and rice-derived polylactic acid 2a are stored in the primary fermentation tank 12 and sealed, and kept at a temperature of 25 to 60°C, preferably 35 to 45°C. Let it ferment with lactic acid for about 3 weeks. At this time, the egg shell and the like are decomposed by the lactic acid, and the calcium contained in the egg shell and the like dissolves onto the lactic acid, so that lactic acid containing calcium is formed. Further, during fermentation, carbon dioxide gas is generated and filled in the primary fermentation tank 12, so an appropriate amount of gas components are discharged into the gas processing tank 19 at any time, and after the gas is discharged, the tank is sealed again and fermentation continues.

After fermentation, the first separation means 13 separates the fermented product into a liquid part and a solid part. The liquid part of the separated fermented product is stored in the secondary fermentation tank 15, sealed tightly, and maintained at a temperature of 25 to 60°C, preferably 35 to 45°C, until the pH of the fermented product is 2.2 to 2. Ferment again until it reaches .6. At this time, vegetable starch containing a large amount of calcium is decomposed by sugar, which can promote re-fermentation of lactic acid bacteria containing a large amount of calcium. Note that the solid portion of the separated fermented product is sent to the fertilizer forming means 20 and reused as fertilizer.

Precipitated starch is separated from the re-fermented product to stabilize the water content of the re-fermented product. The stabilized re-fermented product is separated into a liquid part and a solid part by the second separation means 16. The dehumidifying means 17 atomizes water to the liquid part of the separated re-fermented product at a temperature of 25 to 50° C. for 5 to 6 hours using ultrasonic vibrations of 2.4 MHz, and the dehumidifying function evaporates the water. let This allows lactic acid to be extracted. The extracted lactic acid is placed in an aluminum container and heated at a temperature of 190 to 230°C for 10 minutes to 1 hour to polymerize the lactic acid. The polymerized lactic acid is placed in a silicone or clay container and cooled to solidify. Thereby, polylactic acid 2c for a binder containing calcium can be obtained.

[Manufacture of polylactic acid for binder derived from konnyaku]
In the method for producing polylactic acid according to the embodiment of the present invention, when the raw material plant 1 includes konjac potato, the pretreatment means 11 first cuts the konjac potato into pieces and powders it to form a plant-based raw material. do.

Next, the pretreated plant-based raw materials and sugar or rice-derived polylactic acid 2a are stored in the primary fermentation tank 12 and sealed, and maintained at a temperature of 25 to 60°C, preferably 35 to 45°C. Let it ferment with lactic acid for about 2 to 3 weeks. At this time, the starch in konjac potatoes is decomposed by lactic acid, forming konjac-derived lactic acid. Further, during fermentation, carbon dioxide gas is generated and filled in the primary fermentation tank 12, so an appropriate amount of gas components are discharged into the gas processing tank 19 at any time, and after the gas is discharged, the tank is sealed again and fermentation continues.

After fermentation, the first separation means 13 separates the fermented product into a liquid part and a solid part. The liquid part of the separated fermented product is stored in the secondary fermentation tank 15, sealed tightly, and maintained at a temperature of 25 to 60°C, preferably 35 to 45°C, until the pH of the fermented product is 2.2 to 2. Ferment again until it reaches .6. This causes the re-fermented product to become sticky. Note that the solid portion of the separated fermented product is sent to the fertilizer forming means 20 and reused as fertilizer.

Precipitated starch is separated from the re-fermented product to stabilize the water content of the re-fermented product. The stabilized re-fermented product is separated into a liquid part and a solid part by the second separation means 16. The dehumidifying means 17 atomizes water to the liquid part of the separated re-fermented product at a temperature of 25 to 50° C. for 5 to 6 hours using ultrasonic vibrations of 2.4 MHz, and the dehumidifying function evaporates the water. let This allows lactic acid to be extracted. The extracted lactic acid is placed in an aluminum container and heated at a temperature of 190 to 230°C for 10 minutes to 1 hour to polymerize the lactic acid. The polymerized lactic acid is placed in a silicone or clay container and cooled to solidify. This makes it possible to obtain sticky polylactic acid 2d for a binder derived from konjac.

As described above, the method for producing polylactic acid and the apparatus for producing polylactic acid according to the embodiment of the present invention re-ferment the liquid part of the fermented product that has been subjected to lactic acid fermentation in the primary fermentation tank 12 in the secondary fermentation tank 15. By doing so, the pH after re-fermentation can be stabilized. By using the liquid part of the re-fermented product with stable pH, polylactic acid 2 of uniform quality can be obtained. Furthermore, by carrying out the fermentation of plant-based raw materials in two stages, the primary fermentation tank 12 and the secondary fermentation tank 15, the fermentation period can be made shorter than when fermentation is carried out in one stage. Manufacturing period can be shortened. For example, in the case of rice-derived polylactic acid 2a, it takes about 2 weeks, and in the case of polylactic acids 2b, 2c, and 2d for binders, it takes about 2 to 4 weeks by preparing rice-derived polylactic acid 2a in advance. Polylactic acid 2 can be obtained efficiently in a relatively short period of time.

[Manufacture of biodegradable plastics]
In the method for producing biodegradable plastic according to the embodiment of the present invention, first, rice-derived polylactic acid 2a and binder polylactic acids 2b, 2c, and 2d are mixed at a temperature of 190 to 230°C using stirring means 21. Mix and stir while heating for 30 minutes to 1 hour. At this time, polylactic acids 2b, 2c, and 2d for binders are mixed and stirred at a ratio of 5 to 30% by weight with respect to rice-derived polylactic acid 2a. The polylactic acid for the binder to be mixed may be polylactic acid 2b for the binder containing alginic acid, polylactic acid 2c for the binder containing calcium, and a binder derived from konjac, depending on the performance to be imparted to the biodegradable plastic 3 to be produced. It is preferable to use one to a plurality of polylactic acids 2d.

Next, the mixture after mixing and stirring is heated at a temperature of 80° C. by the raw material producing means 22 to remove water, and the mixture is subjected to polylactic oxidation. The polylactic oxidized mixture is stored in a container of the solidifying means 23, cooled, and solidified. Thereby, biodegradable plastic 3 can be obtained.

In the biodegradable plastic manufacturing method and biodegradable plastic manufacturing apparatus of the embodiment of the present invention, since rice-derived polylactic acid 2a is used, it is possible to manufacture biodegradable plastic 3 having biodegradability. can. Furthermore, by mixing polylactic acid 2c containing calcium as a binder with rice-derived polylactic acid 2a, the resulting biodegradable plastic 3 can be made harder. By mixing the rice-derived polylactic acid 2a with the binder polylactic acid 2b containing alginic acid, the adhesiveness increases and it becomes easier to form it into any shape such as a pellet. Moreover, flexibility can be added to the obtained biodegradable plastic 3, and the biodegradable plastic 3 can be made difficult to break. A highly viscous biodegradable plastic can be obtained by mixing rice-derived polylactic acid 2a with konjac-derived polylactic acid 2d for a binder. As described above, according to the biodegradable plastic manufacturing method and the biodegradable plastic manufacturing apparatus of the embodiment of the present invention, it is possible to obtain a biodegradable plastic having better performance.

1 Raw material plant 2 Polylactic acid 2a Rice-derived polylactic acid 2b Polylactic acid for binder containing alginic acid 2c Polylactic acid for binder containing calcium 2d Polylactic acid for binder derived from konjac 3 Biodegradable plastic 11 Pretreatment means 12 Primary fermentation tank 13 First separation means 14 Heating means 15 Secondary fermentation tank 16 Second separation means 17 Dehumidification means 18 Polymerization means 19 Gas treatment tank 20 Fertilization means 21 Stirring means 22 Raw material production means 23 Solidification means

Claims (11)

A first fermentation step in which the plant-based raw material is hermetically sealed and fermented with lactic acid;
a first separation step of separating the fermented product from the first fermentation step into a liquid part and a solid part;
a second fermentation step in which the liquid part of the fermented product separated in the first separation step is sealed and re-fermented;
a second separation step of separating the re-fermented product from the second fermentation step into a liquid part and a solid part;
a dehumidification step of evaporating water from the liquid part of the re-fermented product separated in the second separation step to extract lactic acid;
A polymerization step of heating and polymerizing the lactic acid extracted in the dehumidification step to obtain polylactic acid,
A method for producing polylactic acid, comprising: In the first fermentation step, the plant-based raw material is fermented in a sealed manner for 5 to 25 days,
In the second fermentation step, the liquid part of the fermented product is re-fermented in a sealed state at a temperature of 25 to 60°C so that the pH of the liquid part is 2.2 to 2.6,
In the dehumidification step, water is atomized and evaporated by ultrasonic vibration to the liquid part of the re-fermented product separated in the second separation step,
The polymerization step includes heating the lactic acid at a temperature of 190 to 230°C for 10 minutes to 1 hour to polymerize it,
The method for producing polylactic acid according to claim 1. A claim characterized in that the plant-based raw material includes at least one of white rice, brown rice, hulled rice, germinated rice, kelp, wakame, sargassum, egg shell, cycad fruit, shellfish shell, and konjac potato. 2. The method for producing polylactic acid according to 1 or 2. The first step is to carry out lactic acid fermentation by sealing the plant-based raw material containing at least one of white rice, brown rice, unhulled rice, or germinated rice at a temperature of 25 to 60°C for 5 to 10 days so that the pH of the fermented product is lowered to 4 or less. fermentation process,
a first separation step of separating the fermented product from the first fermentation step into a liquid part and a solid part;
A heating step of heating the liquid part of the fermented product separated in the first separation step at a temperature of 60 to 100° C. for 20 minutes to 1 hour to treat it with germs;
A second step of re-fermenting the liquid part of the fermented product by sealing it at a temperature of 25 to 60°C so that the pH of the liquid part of the fermented product treated with germs in the heating step becomes 2.2 to 2.6. fermentation process,
a second separation step of separating the re-fermented product from the second fermentation step into a liquid part and a solid part;
a dehumidification step of evaporating water from the liquid part of the re-fermented product separated in the second separation step to extract lactic acid;
A polymerization step in which the lactic acid extracted in the dehumidification step is polymerized by heating at a temperature of 190 to 230° C. for 10 minutes to 1 hour to obtain polylactic acid,
A method for producing rice-derived polylactic acid, characterized by comprising: The rice produced by the method for producing rice-derived polylactic acid according to claim 4 is added to a plant-based raw material containing at least one of kelp, wakame, sargassum, egg shell, cycad fruit, shell, or konnyaku potato. A first fermentation step in which polylactic acid derived from the plant is added, sealed for 10 to 25 days, and lactic acid fermented;
a first separation step of separating the fermented product from the first fermentation step into a liquid part and a solid part;
The liquid part of the fermented product separated in the first separation step is sealed at a temperature of 25 to 60°C and re-fermented so that the pH of the liquid part of the fermented product becomes 2.2 to 2.6. 2 fermentation process and
a second separation step of separating the re-fermented product from the second fermentation step into a liquid part and a solid part;
a dehumidification step of evaporating water from the liquid part of the re-fermented product separated in the second separation step to extract lactic acid;
A polymerization step in which the lactic acid extracted in the dehumidification step is polymerized by heating at a temperature of 190 to 230° C. for 10 minutes to 1 hour to obtain polylactic acid,
A method for producing polylactic acid for a binder, comprising: A primary fermentation tank in which plant-based raw materials are sealed and fermented with lactic acid,
a first separation means for separating the fermented product fermented in the primary fermentation tank into a liquid part and a solid part;
a secondary fermentation tank in which the liquid part of the fermented product separated by the first separation means is sealed and re-fermented;
a second separation means for separating the re-fermented product re-fermented in the secondary fermentation tank into a liquid part and a solid part;
a dehumidifying means for extracting lactic acid by evaporating water from the liquid part of the re-fermented product separated by the second separating means;
a polymerization means for heating and polymerizing the lactic acid extracted by the dehumidification means to obtain polylactic acid;
An apparatus for producing polylactic acid, comprising: comprising a heating means for heating the liquid part of the fermented product separated by the first separating means to treat it with germs;
The plant-based raw material includes at least one of white rice, brown rice, unhulled rice, or germinated rice,
The secondary fermentation tank is configured to re-ferment the liquid part of the fermented product that has been treated with germs by the heating means in a sealed manner.
The apparatus for producing polylactic acid according to claim 6. The rice-derived polylactic acid obtained by the method for producing rice-derived polylactic acid according to claim 4 and the polylactic acid for binder obtained by the method for producing polylactic acid for binder according to claim 5 are mixed while heating. a stirring step of stirring;
A raw material manufacturing step of removing water after mixing and stirring and oxidizing the mixture with polylactic;
A solidification step of cooling and solidifying the polylactic oxidized mixture to obtain a biodegradable plastic,
A method for producing biodegradable plastic, characterized by comprising: In the stirring step, the rice-derived polylactic acid and the binder polylactic acid are mixed and stirred while heating at a temperature of 190 to 230°C for 30 minutes to 1 hour,
The raw material manufacturing process includes removing water and polylactic oxidizing the mixture at a temperature of 70 to 90°C.
The method for producing a biodegradable plastic according to claim 8. The biodegradable plastic according to claim 8 or 9, characterized in that in the stirring step, the polylactic acid for the binder is mixed and stirred at a ratio of 5 to 30% by weight with respect to the rice-derived polylactic acid. Production method. The apparatus for producing polylactic acid according to claim 6 or 7,
a stirring means for mixing and stirring a plurality of types of polylactic acid obtained by the polylactic acid production apparatus while heating;
After mixing and stirring with the stirring means, a raw material producing means removes water and oxidizes the mixture with polylactic;
a solidifying means for obtaining a biodegradable plastic by cooling and solidifying the polylactic-oxidized mixture in the raw material manufacturing means;
A biodegradable plastic manufacturing device characterized by comprising:

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