Synthesis device and synthesis method of a polyester polycarbonate copolymer diol

Abstract

The present invention discloses a synthesis device and a synthesis method for polyester polycarbonate copolymer diol. By using phthalic anhydride or terephthalic acid, diol, and carbon dioxide for at least three copolymerization reactions, a polyester polycarbonate copolymer diol with a large molecular weight is synthesized, obtaining a diol containing a polyester polycarbonate block copolymer and having different sequence structures. Compared with traditional polyether diols, it has better antioxidant performance and biodegradability; its product, the polyester polycarbonate copolymer diol, can be used for subsequent synthesis of plastics or polyurethanes, and is beneficial to enhancing and improving the physical properties of polymers such as polyurethanes, effectively ensuring the quality and yield of copolymer products; at the same time, by synthesizing the copolymer diol through this scheme, the catalytic system used can completely carry out under normal pressure / vacuum conditions, the reaction conditions are very mild, no dehydrating agent needs to be introduced, the raw material cost used is lower, and it is more suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of polyester polycarbonate copolymer diols, their synthesis processes and reaction apparatuses, and particularly to a technology for copolymerizing phthalic anhydride or phthalic acid, aliphatic diols and carbon dioxide to synthesize non-polyether type and biodegradable diols. Background Art

[0002] Since the Industrial Revolution, the emissions of greenhouse gases have been increasing year by year, causing global warming, the continuous accumulation of the greenhouse effect, and triggering a series of environmental and ecological problems. The main greenhouse gas causing these problems is carbon dioxide.

[0003] Therefore, how to reasonably and effectively utilize carbon dioxide not only conforms to the strategic direction of national policies, but also is a green technical route for effectively utilizing carbon resources, turning waste into treasure, and reducing the greenhouse effect.

[0004] Nowadays, the resource utilization of carbon dioxide has always been an important issue in a sustainable development society. Especially taking carbon dioxide as a valuable one-carbon resource, many researchers have done a lot of work. For example, using the reaction of carbon dioxide with alcohols to produce carbonate chemical products is one of the important ideas.

[0005] Regarding the synthesis processes and apparatuses of polyester polycarbonate copolymer diols, there are also some relatively mature synthesis processes and reaction apparatuses in the current market, but they cannot be carried out under normal pressure / vacuum conditions, the reaction conditions are relatively harsh, not very suitable for large-scale production, and the quality and yield of copolymer products cannot be guaranteed. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a synthesis process of biodegradable polyester polycarbonate copolymer diols, which can be carried out under normal pressure / vacuum conditions, the reaction conditions are very mild, and it is more suitable for large-scale production.

[0007] Meanwhile, the present invention also provides a synthesis apparatus of biodegradable polyester polycarbonate copolymer diols, which does not need to introduce a dehydrating agent, has a lower cost, and is more suitable for large-scale production.

[0008] In addition, the present invention also provides a biodegradable polyester polycarbonate copolymer diol, which can help enhance and improve the performance of polymers and effectively guarantee the quality and yield of copolymer products.

[0009] The technical solution of the present invention is as follows: A synthesis apparatus of biodegradable polyester polycarbonate copolymer diols includes a raw material kettle, at least three polymerization reaction kettles, a storage unit and a drying tower;

[0010] The upper part of the raw material kettle is provided with a raw material inlet of the raw material kettle, the lower part is provided with a gas inlet of the raw material kettle, and the bottom is provided with a raw material outlet of the raw material kettle; the raw material inlet of the raw material kettle is used to add diol, solvent, and phthalic anhydride or terephthalic acid into the raw material kettle through a pipeline, the gas inlet of the raw material kettle is used to introduce nitrogen with a certain air pressure into the raw material kettle through a pipeline, and the raw material outlet of the raw material kettle is connected to the raw material inlet of the first polymerization reactor through a pipeline;

[0011] The upper part of each polymerization reactor is provided with its own raw material inlet, the top is provided with its own gas outlet, the bottom is provided with its own gas inlet, and the lower part is provided with its own product outlet; the gas inlet is used to introduce carbon dioxide with a certain air pressure into the corresponding polymerization reactor through a pipeline respectively, and the gas outlet is used to discharge the unreacted carbon dioxide in the corresponding polymerization reactor;

[0012] Between multiple interconnected polymerization reactors, the product outlet of the previous polymerization reactor is connected to the raw material inlet of the next polymerization reactor through a corresponding pipeline; the product outlet of the last polymerization reactor is connected to the inlet end of the storage unit through a pipeline, and the outlet end of the storage unit is the outlet end of the target product copolymer diol;

[0013] The gas outlets of all the polymerization reactors are aggregated through pipelines and then connected to the inlet end of the drying tower, and the outlet end of the drying tower is aggregated through pipelines to the main gas inlet pipeline and then returned to the input pipeline, which is used to collect the unreacted carbon dioxide in all the polymerization reactors and recycle it after drying by the drying tower.

[0014] In the synthesis device of the biodegradable polyester polycarbonate copolymer diol, wherein: a delivery pump is arranged on the pipeline connecting the product outlet of the previous polymerization reactor and the raw material inlet of the next polymerization reactor, which is used to transport the liquid product at the lower part of the previous polymerization reactor to the upper part of the next polymerization reactor.

[0015] In the synthesis device of the biodegradable polyester polycarbonate copolymer diol, wherein: a stirring device is arranged in the raw material kettle.

[0016] In the synthesis device of the biodegradable polyester polycarbonate copolymer diol, wherein: all the polymerization reactors adopt fixed-bed reactors, the internal stationary phase is a catalyst, the lower part is provided with a corresponding gas inlet end, the gas can flow from the lower part to the upper part, and the upper part is provided with a corresponding raw material inlet end, the liquid can flow from the upper part to the lower part.

[0017] In the synthesis device of the biodegradable polyester polycarbonate copolymer diol, wherein: the aspect ratio of the raw material kettle is between 3 and 5, and the aspect ratio of each polymerization reactor is also between 3 and 5.

[0018] The synthesis device of the biodegradable polyester polycarbonate copolymer diol, wherein: the diameters of the pipelines connecting the product outlet of the previous polymerization reactor and the raw material inlet of the next polymerization reactor are all between 50 and 100 mm; a gas distributor is connected to the gas inlet of each polymerization reactor, and the pore diameters on the gas distributor are between 1 and 5 mm.

[0019] A synthesis method of a biodegradable polyester polycarbonate copolymer diol, which is applied in the synthesis device of the biodegradable polyester polycarbonate copolymer diol described in any one of the above, and this synthesis method includes the following steps:

[0020] Step S110: Inject excessive diol and a certain amount of phthalic anhydride or terephthalic acid into the raw material kettle through the pipeline and the raw material inlet of the raw material kettle. While stirring and mixing, introduce a certain amount of nitrogen through the pipeline and the gas inlet of the raw material kettle, and stir for a period of time under a nitrogen atmosphere to enable part of the diol to undergo an esterification reaction with phthalic anhydride or terephthalic acid in a ratio of 1:1 to obtain esterified diol.

[0021] Step S120: Inject the mixture of unesterified diol and esterified diol in the raw material kettle into the upper part of the first polymerization reactor through the pipeline and the raw material inlet, flow from the upper part to the lower part through the stationary phase, and introduce carbon dioxide gas into the first polymerization reactor through the pipeline and the gas inlet, and blow from the lower part to the upper part through the stationary phase. The diol, esterified diol and carbon dioxide undergo a polymerization reaction at the stationary phase catalyst to obtain a polyester polycarbonate copolymer diol.

[0022] Step S130: After passing through all the polymerization reactors, obtain a polyester polycarbonate copolymer diol with a molecular weight of more than 2000, and transport it to the storage unit through the pipeline for storage as a reaction raw material.

[0023] The synthesis method of the biodegradable polyester polycarbonate copolymer diol, wherein:

[0024] In step S110, add terephthalic acid and ethylene glycol into the raw material kettle, and the molar ratio of the two is 1:2.05, and stir and react at 215 °C for 10 h;

[0025] In steps S120 and S130, control the reaction temperature of all polymerization reactors at 210 °C to obtain a polyester polycarbonate copolymer diol with a molecular weight of 3000.

[0026] A biodegradable polyester polycarbonate copolymer diol, whose molecular formula is , Among them, a, b, and n are all integers greater than 1; and this biodegradable polyester polycarbonate copolymer diol is prepared by the synthesis method of the biodegradable polyester polycarbonate copolymer diol described in claim 7.

[0027] A biodegradable polyester polycarbonate copolymer diol, its synthesis device and method provided by the present invention utilize phthalic anhydride or terephthalic acid, diol, and carbon dioxide to carry out at least three copolymerization reactions to synthesize a polyester polycarbonate copolymer diol with a large molecular weight, obtaining a diol containing a polyester polycarbonate block copolymer, and there are different sequence structures. Compared with traditional polyether diols, it has better antioxidant performance and biodegradability; its product, the polyester polycarbonate copolymer diol, can be used for subsequent synthesis of plastics or polyurethanes, and is beneficial to enhancing and improving the physical properties of polymers such as polyurethanes, which can effectively ensure the quality and yield of copolymer products; at the same time, by synthesizing the copolymer diol through this scheme, the catalytic system used can completely carry out under normal pressure / vacuum conditions, the reaction conditions are very mild, and there is no need to introduce a dehydrating agent. The raw materials used have lower costs and are more suitable for large-scale production. Brief Description of the Drawings

[0028] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure of the present invention in any way; the shapes and proportional dimensions of the components in the drawings are only schematic and are used to assist in understanding the present invention, rather than specifically defining the shapes and proportional dimensions of the components of the present invention; those skilled in the art can select various possible shapes and proportional dimensions according to specific circumstances to implement the present invention under the teaching of the present invention.

[0029] Figure 1 is a schematic structural diagram of an embodiment of the synthesis device of the biodegradable polyester polycarbonate copolymer diol of the present invention;

[0030] Figure 2 is a schematic diagram of the synthesis path and process of the biodegradable polyester polycarbonate copolymer diol of the present invention;

[0031] Figure 3 is a specific adjustment experimental data table for synthesizing the biodegradable polyester polycarbonate copolymer diol of the present invention;

[0032] Summary of each label in the figure: raw material kettle 1, raw material inlet of raw material kettle 1-1, gas inlet of raw material kettle 1-2, raw material outlet of raw material kettle 1-3, first polymerization reactor 2, first raw material inlet 2-1, first gas inlet 2-2, first gas outlet 2-3, first product outlet 2-4, second polymerization reactor 3, second raw material inlet 3-1, second gas inlet 3-2, second gas outlet 3-3, second product outlet 3-4, third polymerization reactor 4, third raw material inlet 4-1, third gas inlet 4-2, third gas outlet 4-3, third product outlet 4-4, storage unit 5, inlet end 5-1 (of storage unit 5), outlet end 5-2 (of storage unit 5), drying tower 6, inlet end 6-1 (of drying tower 6), outlet end 6-1 (of drying tower 6), transfer pumps (7, 8), pipelines (9, 10, 11, 12, 13, 14, 15, 16, 17, 18). Detailed implementation manners

[0033] Hereinafter, in conjunction with the accompanying drawings, the detailed implementation manners and embodiments of the present invention will be described in detail. The described specific embodiments are only used to explain the present invention and are not used to limit the specific implementation manners of the present invention.

[0034] As Figure 1 shown, Figure 1 is a schematic structural diagram of an embodiment of the synthesis device of the biodegradable polyester polycarbonate copolymer diol of the present invention. The synthesis device (or reaction device) of the biodegradable polyester polycarbonate copolymer diol of the present invention includes a raw material kettle 1, three polymerization reactors (2, 3, 4), a storage unit 5 and a drying tower 6; wherein:

[0035] The upper part of the raw material kettle 1 is provided with a raw material inlet 1-1 of the raw material kettle, the lower part is provided with a gas inlet 1-2 of the raw material kettle, and the bottom is provided with a raw material outlet 1-3 of the raw material kettle; the raw material inlet 1-1 of the raw material kettle is used to add diol, solvent and phthalic anhydride or terephthalic acid into the raw material kettle 1 through the pipeline 9, the gas inlet 1-2 of the raw material kettle is used to introduce nitrogen with a certain air pressure into the raw material kettle 1 through the pipeline 10, and the raw material outlet 1-3 of the raw material kettle is connected to the first raw material inlet 2-1 of the first polymerization reactor 2 through the pipeline 11;

[0036] For the three polymerization reactors (2, 3, 4), each of them is provided with its own raw material inlet (2-1, 3-1, 4-1) at the upper part, its own gas outlet (2-3, 3-3, 4-3) at the top, its own gas inlet (2-2, 3-2, 4-2) at the bottom, and its own product outlet (2-4, 3-4, 4-4) at the lower part; the gas inlets (2-2, 3-2, 4-2) are used to introduce carbon dioxide at a certain air pressure into the corresponding polymerization reactors (2, 3, 4) respectively through pipeline 12, and the gas outlets (2-3, 3-3, 4-3) are used to discharge the unreacted carbon dioxide in the corresponding polymerization reactors (2, 3, 4).

[0037] Moreover, between the three interconnected polymerization reactors (2, 3, 4), the product outlets (2-4, 3-4) of the previous polymerization reactors (2, 3) are connected to the raw material inlets (3-1, 4-1) of the subsequent polymerization reactors (3, 4) through the corresponding pipelines (14, 15); the third product outlet 4-4 of the third polymerization reactor 4 is connected to the inlet end 5-1 of the storage unit 5 through pipeline 16, and the outlet end 5-2 of the storage unit 5 is the outlet end of the target product copolymer diol.

[0038] The gas outlets (2-3, 3-3, 4-3) of the three polymerization reactors (2, 3, 4) are aggregated through pipeline 13 and then connected to the inlet end 6-1 of the drying tower 6, and the outlet end 6-2 of the drying tower 6 is aggregated through pipeline 17 to the gas total inlet pipeline 18 and then returned to the input pipeline 12, for collecting the unreacted carbon dioxide in the three polymerization reactors (2, 3, 4) and recycling it after drying by the drying tower 6.

[0039] Specifically, a first transfer pump 7 is provided on the pipeline 14 connecting the product outlet 2-4 of the first polymerization reactor 2 and the raw material inlet 3-1 of the second polymerization reactor 3, for transporting the liquid product at the lower part of the first polymerization reactor 2 to the upper part of the second polymerization reactor 3; a first transfer pump 8 is provided on the pipeline 15 connecting the product outlet 3-4 of the second polymerization reactor 3 and the raw material inlet 4-1 of the third polymerization reactor 4, for transporting the liquid product at the lower part of the second polymerization reactor 3 to the upper part of the third polymerization reactor 4.

[0040] Preferably, a stirring device is provided in the raw material kettle 1 to more favorably uniformly mix the raw materials in the raw material kettle 1 and accelerate the completion of the first-step reaction.

[0041] Preferably, the three polymerization reactors (2, 3, 4) all adopt fixed-bed reactors, the internal stationary phases are all catalysts, the corresponding gas inlet ends are provided at the lower part, the gas can flow from the lower part to the upper part, and the corresponding raw material inlet ends are provided at the upper part, the liquid can flow from the upper part to the lower part, so as to more favorably realize the mixing of gas-liquid-solid three phases.

[0042] Specifically, the aspect ratio of the raw material kettle 1 is between 3 and 5, and the aspect ratio of each polymerization reactor (2, 3, 4) is also between 3 and 5.

[0043] Specifically, the diameters of the pipelines (14, 15) connecting the product outlets (2-4, 3-4) of the previous polymerization reactors (2, 3) and the raw material inlets (3-1, 4-1) of the subsequent polymerization reactors (3, 4) are all between 50 and 100 mm; a gas distributor (not shown in the figure) is connected to the gas inlets (2-2, 3-2, 4-2) of the three polymerization reactors (2, 3, 4), and the pore diameters on the gas distributor are between 1 and 5 mm.

[0044] The above embodiments of the synthesis device of the biodegradable polyester polycarbonate copolymer diol are all exemplified by three series-connected polymerization reactors (2, 3, 4), but more than three polymerization reactors can be used for the above series connection according to the actual production scale.

[0045] Based on the above embodiments of the synthesis device of the biodegradable polyester polycarbonate copolymer diol, the present invention proposes a synthesis method of the biodegradable polyester polycarbonate copolymer diol, which is applied in the above synthesis device of the biodegradable polyester polycarbonate copolymer diol, combined with Figure 2 as shown Figure 2 is a schematic diagram of the synthesis path and process of the biodegradable polyester polycarbonate copolymer diol of the present invention. Still taking three series-connected polymerization reactors (2, 3, 4) as an example, the synthesis method mainly includes the following steps:

[0046] Step S110: Inject an excessive amount of diol (such as ethylene glycol or propylene glycol) and a certain amount of phthalic anhydride or terephthalic acid into the raw material kettle 1 through the pipeline 9 and the raw material inlet 1-1 of the raw material kettle. While stirring and mixing, introduce a certain amount of nitrogen through the pipeline 10 and the gas inlet 1-2 of the raw material kettle, and stir for a period of time under a nitrogen atmosphere, so that part of the diol (i.e., substance B in the first reaction formula) reacts with phthalic anhydride or terephthalic acid (i.e., substance A in the first reaction formula) in a ratio of 1:1 to obtain an esterified diol (i.e., substance C in the first reaction formula). This is the first step of the reaction;

[0047] Step S120: Inject the mixture of unesterified diol (i.e., substance B in the second reaction formula) and esterified diol (i.e., substance C in the second reaction formula) in the raw material kettle 1 into the upper part of the first polymerization reactor 2 through pipeline 11 and the first raw material inlet 2-1. It flows from the upper part to the lower part through the stationary phase, and introduce carbon dioxide gas (i.e., substance D in the second reaction formula) into the first polymerization reactor 2 through pipeline 12 and the first gas inlet 2-2. It is blown from the lower part to the upper part through the stationary phase. The diol (i.e., substance B in the second reaction formula), esterified diol (i.e., substance C in the second reaction formula) and carbon dioxide (i.e., substance D in the second reaction formula) undergo a polymerization reaction at the stationary phase catalyst to obtain a polyester polycarbonate copolymer diol (i.e., substance F in the second reaction formula, where a, b, and n are all integers greater than 1). This is the second step of the reaction;

[0048] Step S130: After passing through three polymerization reactors (2, 3, 4), a polyester polycarbonate copolymer diol with a molecular weight of more than 2000 is obtained. The product of the third polymerization reactor 4 is collected through the third product outlet 4-4 and transported to the storage unit 5 through pipeline 16 for storage as a reaction raw material for further reaction to produce polymers such as polyurethane.

[0049] Specific embodiment: Taking a 30 L raw material kettle 1 and three series-connected 30 L polymerization reactors (2, 3, 4) as an example, the diameters of the pipelines (11, 14, 15, 16) connected to the respective raw material inlets (2-1, 3-1, 4-1) and respective product outlets (2-4, 3-4, 4-4) of each polymerization reactor (2, 3, 4) are all 50 mm. The end of pipeline 12 for introducing carbon dioxide into each polymerization reactor (2, 3, 4) through their respective gas inlets (2-2, 3-2, 4-2) can be directly connected to a gas distributor (not shown in the figure), and the pore diameters on this gas distributor are all 2 mm.

[0050] Add terephthalic acid and ethylene glycol to the raw material kettle 1, and the molar ratio of the two is 1:2.05. The ethylene glycol is slightly in excess. Purge with nitrogen and stir and react at 215 °C for 10 h; then introduce the raw material liquid in the raw material kettle 1 into the three polymerization reactors (2, 3, 4), change to purge with carbon dioxide, control the reaction temperature at 210 °C. After reacting through the three polymerization reactors (2, 3, 4), the molecular weight of the obtained polyester polycarbonate copolymer diol is 3000; this target product copolymer diol can be used as a reaction raw material for further reaction to produce polymers such as polyurethane, and is beneficial to enhancing and improving the performance of polymers such as polyurethane, ensuring the quality and yield of copolymer products such as polyurethane.

[0051] Based on the above synthesis method of the biodegradable polyester polycarbonate copolymer diol, the present invention also provides a biodegradable polyester polycarbonate copolymer diol, whose molecular formula is , wherein a, b, and n are all integers greater than 1; and the biodegradable polyester polycarbonate copolymer diol is prepared by the above synthesis method of the biodegradable polyester polycarbonate copolymer diol.

[0052] Through the above biodegradable polyester polycarbonate copolymer diol, its synthesis method and reaction device, the obtained product, the biodegradable polyester polycarbonate copolymer diol, has a regular structure and adjustable properties, because the sequence structure of the copolymer diol (i.e., substance F in the second reaction formula) can be controlled by adjusting the dosage ratio of the raw material diol (i.e., Figure 2 substance B in the first reaction formula). The specific adjustment experimental data can be seen in detail in Figure 3 the attached table shown; as can be seen from this attached table, on the one hand, when the dosage of terephthalic acid (i.e., Figure 2 substance A in the first reaction formula) remains unchanged, increasing the dosage ratio of ethylene glycol (i.e., Figure 1 substance B in the first reaction formula), that is, increasing the molar ratio of the two (i.e., substance A: substance B), then the polymer selectivity will increase, the polycarbonate content will decrease, the polyester content will increase, and the molecular weight of the obtained copolymer diol (i.e., Figure 2 substance F in the second reaction formula) will increase; on the other hand, even if the molar ratio of the two (i.e., substance A: substance B) remains unchanged, but when the dosages of both decrease, the molecular weight of the obtained copolymer diol (i.e., Figure 2 substance F in the second reaction formula) will also decrease significantly.

[0053] At the same time, because the benzene rings are separated by carbonate bonds, the biodegradability is better; and the cost of the raw materials (i.e., ethylene glycol or propylene glycol) is lower, which is more suitable for large-scale production; this product can be used for subsequent synthesis of plastics or polyurethanes, which are all beneficial to enhancing the physical properties of the copolymer; in addition, the reaction device for the biodegradable polyester polycarbonate copolymer diol of the present invention is an atmospheric pressure reaction, with low requirements for equipment; there is no need for additional devices for separating the catalyst from the product; nor is it necessary to add a dehydrating agent, and the reaction conditions are mild; and the reaction device realizes the recycling of excess CO2, meeting the requirements of green chemistry.

[0054] Contents not described in detail in this specification belong to the prior art well-known to those of ordinary skill in the art.

[0055] It should be understood that the above are only the preferred embodiments of the present invention, and are not sufficient to limit the technical solutions of the present invention. For those of ordinary skill in the art, within the spirit and principle of the present invention, additions, deletions, substitutions, transformations or improvements can be made according to the above description, and all these technical solutions after the additions, deletions, substitutions, transformations or improvements shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A synthesis device for biodegradable polyester polycarbonate copolymer diol, characterized in that, Including: A raw material kettle, at least three polymerization reaction kettles, a storage unit, and a drying tower; At the upper part of the raw material kettle, there is a raw material inlet of the raw material kettle, at the lower part, there is a gas inlet of the raw material kettle, and at the bottom, there is a raw material outlet of the raw material kettle; the raw material inlet of the raw material kettle is used to add diol, solvent, and phthalic anhydride or terephthalic acid into the raw material kettle through a pipeline, the gas inlet of the raw material kettle is used to introduce nitrogen with a certain air pressure into the raw material kettle through a pipeline, and the raw material outlet of the raw material kettle is connected to the raw material inlet of the first polymerization reaction kettle through a pipeline; At the upper part of each polymerization reaction kettle, there is a respective raw material inlet, at the top, there is a respective gas outlet, at the bottom, there is a respective gas inlet, and at the lower part, there is a respective product outlet; the gas inlet is used to introduce carbon dioxide with a certain air pressure into the corresponding polymerization reaction kettle through a pipeline respectively, and the gas outlet is used to discharge the unreacted carbon dioxide in the corresponding polymerization reaction kettle; Between multiple interconnected polymerization reaction kettles, the product outlet of the previous polymerization reaction kettle is connected to the raw material inlet of the subsequent polymerization reaction kettle through a corresponding pipeline; the product outlet of the last polymerization reaction kettle is connected to the inlet end of the storage unit through a pipeline, and the outlet end of the storage unit is the outlet end of the target product copolymer diol; The gas outlets of all the polymerization reaction kettles are aggregated through a pipeline and connected to the inlet end of the drying tower, and the outlet end of the drying tower is aggregated through a pipeline to the main gas inlet pipeline and then returned to the input pipeline, which is used to collect the unreacted carbon dioxide in all the polymerization reaction kettles and recycle it after drying in the drying tower; On the pipeline connecting the product outlet of the previous polymerization reaction kettle and the raw material inlet of the subsequent polymerization reaction kettle, a transfer pump is provided, which is used to transfer the liquid product at the lower part of the previous polymerization reaction kettle to the upper part of the subsequent polymerization reaction kettle; A stirring device is arranged in the raw material kettle.

2. The synthesis device of the biodegradable polyester polycarbonate copolymer diol according to claim 1, wherein: All the polymerization reaction kettles adopt fixed-bed reaction kettles, the internal stationary phase is a catalyst, a corresponding gas inlet end is arranged at the lower part, and the gas can flow from the lower part to the upper part, and a corresponding raw material inlet end is arranged at the upper part, and the liquid can flow from the upper part to the lower part.

3. The synthesis device of the biodegradable polyester polycarbonate copolymer diol according to claim 1, characterized in that: The aspect ratio of the raw material kettle is between 3 and 5, and the aspect ratio of each polymerization reaction kettle is also between 3 and 5.

4. The synthesis device of the biodegradable polyester polycarbonate copolymer diol according to claim 1, characterized in that: The diameter of the pipeline connecting the product outlet of the previous polymerization reaction kettle and the raw material inlet of the subsequent polymerization reaction kettle is between 50 and 100 mm; at the gas inlet of each polymerization reaction kettle, a gas distributor is connected, and the aperture on the gas distributor is between 1 and 5 mm.

5. A method for synthesizing a biodegradable polyester polycarbonate copolymer diol, which is applied to the synthesis device of the biodegradable polyester polycarbonate copolymer diol according to any one of claims 1 to 4, and is characterized in that, This synthesis method includes the following steps: Step S110: Inject excessive ethylene glycol or propylene glycol and a certain amount of phthalic anhydride or terephthalic acid into the raw material kettle through the pipeline and the raw material inlet of the raw material kettle, while stirring and mixing, introduce a certain amount of nitrogen through the pipeline and the gas inlet of the raw material kettle, and stir for a period of time under a nitrogen atmosphere, so that part of the ethylene glycol or propylene glycol reacts with phthalic anhydride or terephthalic acid in a ratio of 1:1 to obtain esterified diol; Step S120: Inject the mixture of unesterified ethylene glycol or propylene glycol and esterified diol in the raw material kettle into the upper part of the first polymerization reactor through a pipeline and a raw material inlet, flow from the upper part to the lower part through the stationary phase, and introduce carbon dioxide gas into the first polymerization reactor through a pipeline and a gas inlet, blow from the lower part to the upper part through the stationary phase. Polymerization reaction occurs between ethylene glycol or propylene glycol, esterified diol and carbon dioxide at the stationary phase catalyst to obtain polyester polycarbonate copolymer diol; Step S130: After passing through all the polymerization reactors, polyester polycarbonate copolymer diol with a molecular weight of more than 2000 is obtained and transported to the storage unit through a pipeline for storage as reaction raw materials.

6. The synthesis method of the biodegradable polyester polycarbonate copolymer diol according to claim 5, wherein: In step S110, terephthalic acid and ethylene glycol are added to the raw material kettle, and the molar ratio of the two is 1:2.05, and the reaction is stirred at 215 °C for 10 h; In steps S120 and S130, the reaction temperature of all the polymerization reactors is controlled at 210 °C to obtain polyester polycarbonate copolymer diol with a molecular weight of 3000.

7. A biodegradable polyester polycarbonate copolymer diol, characterized in that, Its molecular formula is ， wherein, a, b, and n are all integers greater than 1; and the biodegradable polyester polycarbonate copolymer diol is prepared by the synthesis method of the biodegradable polyester polycarbonate copolymer diol according to claim 5.

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