A system and method for continuous industrial production of high molecular weight crude PGA

Abstract

The application discloses a system and method for continuously and industrially producing high-molecular-weight crude PGA. In a 100,000-3,000,000 tons / year polyglycolide PGA device, three different types of polymerization reactors are connected in series, and polymerization reactions are carried out step by step to obtain high-molecular-weight crude PGA. By using the system and method, the conversion rate of the polymerization reaction is 75%-95%, the molecular weight of the polyglycolide PGA is greater than 150,000, and large-scale industrial continuous production of the polyglycolide PGA product is realized. Moreover, the equipment type is simple, the operation is convenient and easy, and the system and method can be applied to the preparation of polyglycolide products in a polyglycolide PGA industrial production device.

Description

TECHNICAL FIELD

[0001] The present application relates to a system and method for producing polyglycolide (PGA), in particular to a system and method for continuously and industrially producing high molecular weight crude PGA. BACKGROUND

[0002] Polyglycolide, abbreviated as PGA in English, also known as polyglycolic acid or polyhydroxyacetic acid, is the simplest linear aliphatic polyester in structure. The raw material of polyglycolide is α-hydroxyacetic acid, which is widely present in natural crops such as sugar cane, sugar beet and unripe grapes. Due to the low content, it is difficult to separate and extract, so the organic synthesis method is used in industry. High relative molecular mass polyglycolide is generally obtained by ring-opening polymerization of glycolide monomer. Polyglycolide is a high molecular material with good biocompatibility and biodegradability, and has high mechanical properties. The mechanical properties and degradation properties can be adjusted by copolymerization with other monomers. Polyglycolide and its copolymers are widely used in fields such as degradable medical surgical suture, internal fixation of bone fracture, drug controlled release carrier and tissue engineering scaffold.

[0003] US2010234557 discloses a method for preparing aliphatic polyester by ring-opening polymerization of cyclic ester. The cyclic ester is pre-polymerized in a reaction kettle to synthesize polyglycolide with low molecular weight, and then enters a double screw extruder for further polymerization to obtain polyglycolide with high molecular weight. However, the low molecular weight polyglycolide after pre-polymerization needs to be cooled, crushed, and then fed into the double screw extruder through an automatic feeder. There are not many domestic manufacturers of high-performance double screw extruders, and most of the time, imported equipment needs to be purchased, and the price is high, and the later maintenance is difficult.

[0004] 202011136519.4 discloses a system and method for industrial production of PGA product, which uses two polymerization reactors in series, so that the glycolide raw material passes through the primary polymerization reaction and the secondary polymerization reaction in turn to produce qualified polyglycolide PGA product. However, there is no mention of suitable polymerization reactor type that can be applied to large-scale continuous industrial production of PGA. SUMMARY

[0005] The first object of the present application is to provide a system for continuously and industrially producing high molecular weight crude PGA, and the second object of the present application is to provide a method for continuously and industrially producing high molecular weight crude PGA by using the system.

[0006] Technical solution: The system for continuously and industrially producing high molecular weight crude PGA comprises a first-stage polymerization reactor, a feed pump, a second-stage polymerization reactor, a third-stage polymerization reactor and a product pump; the feed pump is connected with the first-stage polymerization reactor and the second-stage polymerization reactor respectively, and the third-stage polymerization reactor is connected with the second-stage polymerization reactor and the product pump respectively.

[0007] Preferably, the first-stage polymerization reactor is a kettle glycolide prepolymer kettle, the second-stage polymerization reactor is a coiled tube reactor, and the third-stage polymerization reactor is a screw belt reactor.

[0008] More preferably, the kettle glycolide prepolymer kettle is provided with a stirring paddle, and the stirring paddle has one of the following structural types: a propeller, a disc type impeller, a folding paddle type impeller, an inclined blade turbine, an open straight blade turbine and a back bending type impeller.

[0009] More preferably, the coiled tube reactor comprises a jacket and a coiled tube, the coiled tube has a tube diameter of 8-12 mm and a heat exchange area of 150-200 m 2 / m 3 .

[0010] More preferably, the screw belt reactor is provided with a screw belt stirring paddle, the screw belt stirring paddle has a single screw belt type or a double screw belt type, the ratio of the diameter Dj of the screw belt stirring paddle to the inner diameter Di of the screw belt reactor is 0.92-0.98:1, and the rotating speed of the screw belt stirring paddle is 40-60 RPM.

[0011] The method for continuously and industrially producing high molecular weight crude PGA comprises the following steps:

[0012] a. The mixture of molten glycolide and a catalyst enters the first-stage polymerization reactor for polymerization reaction to obtain a first-stage polymerization product;

[0013] b. The first-stage polymerization product is pressurized by the feed pump and then enters the second-stage polymerization reactor, cooling medium feed and cooling medium feed are introduced into the jacket and the coiled tube of the second-stage polymerization reactor, and the first-stage polymerization product is further polymerized to obtain a second-stage polymerization product;

[0014] c. The second-stage polymerization product enters the third-stage polymerization reactor, the deactivator and the antioxidant are added to the bottom of the third-stage polymerization reactor, and the second-stage polymerization product is subjected to adiabatic polymerization reaction to obtain the crude PGA product which is delivered to the outside of the system by the product pump.

[0015] Preferably, in step b, the cooling medium feed and the cooling medium feed are heat conducting oils.

[0016] Preferably, in step c, the deactivating agent is one of sodium polysulfide, sulfur-containing compounds, and the antioxidant is one of stearyl propionate, phosphite ester;

[0017] Preferably, in step a, the first-stage polymerization reactor has an operating temperature of 120-220°C and an operating pressure of 0-0.5 MPaG; the polymerization reaction has a reaction time of 0.3-1.2 h and a conversion rate of 15%-35%; the mass ratio of the catalyst to the molten glycolide is 0.0001-0.001:1; in step b, the second-stage polymerization reactor has an operating temperature of 100-250°C and an operating pressure of 0.0-0.5 MPaG; the polymerization reaction has a reaction time of 0.8-2.0 h and a conversion rate of 65%-85%; in step c, the third-stage polymerization reactor has an operating temperature of 120-300°C and an operating pressure of -0.10-0.00 MPaG; the adiabatic polymerization reaction has a reaction time of 0.5-2.0 h and a conversion rate of 75%-95%.

[0018] More preferably, the first-stage polymerization reactor has an operating temperature of 150-200°C and an operating pressure of 0-0.3 MPaG; the polymerization reaction has a reaction time of 0.5-1.0 h and a conversion rate of 20%-30%; the mass ratio of the catalyst to the molten glycolide is 0.0002-0.0006:1; the second-stage polymerization reactor has an operating temperature of 140-220°C and an operating pressure of 0.0-0.3 MPaG; the polymerization reaction has a reaction time of 1.2-1.8 h and a conversion rate of 70%-80%; the third-stage polymerization reactor has an operating temperature of 150-250°C and an operating pressure of -0.10--0.07 MPaG; the adiabatic polymerization reaction has a reaction time of 0.8-1.5 h and a conversion rate of 80%-90%.

[0019] The reaction product obtained by mixing the molten glycolide raw material with the catalyst mixture for the polymerization reaction in the first-stage polymerization reactor is pressurized by a feed pump and fed into the second-stage polymerization reactor for further polymerization. The jacket and the reactor coil of the second-stage polymerization reactor are filled with a heat-conducting oil cooling medium, and the heat generated by the polymerization reaction is removed by the cooling medium to prevent the reactor temperature from rising due to heat accumulation. The reaction product flowing out of the top of the second-stage polymerization reactor is fed into the third-stage polymerization reactor for adiabatic polymerization. A deactivating agent is added to the bottom of the third-stage polymerization reactor to terminate the polymerization reaction, and an antioxidant is added to prevent the generated PGA from being oxidized at high temperature. The PGA product obtained from the bottom of the third-stage polymerization reactor is transported to the downstream by a product pump for separation, purification, and refining.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention uses three different types of polymerization reactors in series to carry out the polymerization reaction step by step to obtain high molecular weight crude PGA. The polymerization reaction conversion rate is 75% to 95%, and the molecular weight of polyglycolic acid is greater than 150,000. Moreover, the equipment is simple and easy to operate, and it is suitable for large-scale industrial continuous production of polyglycolic acid PGA products. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0023] Example 1

[0024] The system and method for continuous industrial production of high molecular weight crude PGA according to the present invention, wherein the first-stage polymerization reactor 1 is a batch-type glycolide prepolymerization reactor, the second-stage polymerization reactor 3 is a coiled reactor, and the third-stage polymerization reactor 4 is a ribbon reactor.

[0025] like Figure 1 As shown, the process flow of this embodiment is as follows: molten glycolide raw material and catalyst mixture 6 enter a batch-type glycolide prepolymerization reactor for prepolymerization reaction. The reaction product 7 flowing out from the bottom of the prepolymerization reactor is pressurized by feed pump 2 to become high-pressure reaction product 8, which is then sent to the bottom of the coiled tube reactor for further polymerization reaction. Cooling medium feed 10 and cooling medium feed 12 are introduced into the jacket and coiled tube of the coiled tube reactor to remove the heat released by the polymerization reaction in time. Cooling medium discharge 11 and cooling medium discharge 13 flow out from the jacket and coiled tube of the coiled tube reactor, thereby controlling the outlet temperature of the coiled tube reactor. The second-stage polymerization product 9 flowing out from the top of the coiled tube reactor enters a ribbon reactor for adiabatic polymerization reaction. The ribbon continuously renews the material adhering to the reactor wall and pushes the material downstream. At the same time, deactivating agent 14 and antioxidant 15 are added to the bottom of the ribbon reactor. The crude glycolide PGA product 16 obtained from the bottom outlet of the ribbon reactor is transported to the downstream 17 for separation, purification and refining processing by product pump 5.

[0026] The deactivating agent 14 can be one of sodium polysulfide or sulfur-containing compounds, and the antioxidant 15 can be one of octadecyl propionate or phosphite.

[0027] The process operating parameters of the embodiment are as follows: in a 10,000 tons / year production scale polyglycolide PGA production device, the glycolide raw material feed amount is 1.88 t / h; the kettle type glycolide prepolymer kettle is provided with a propeller structure type stirring paddle, the winding pipe of the around pipe reactor is 8 mm in diameter, the heat exchange area is 200 m 2 / m 3 , the single screw stirring paddle is provided in the screw belt reactor, the ratio of the diameter Dj of the screw stirring paddle to the inner diameter Di of the screw belt reactor is 0.92:1, the screw stirring paddle speed is 60 RPM; the operating temperature of the kettle type glycolide prepolymer kettle is 180℃, the operating pressure is 0.2 MPaG, the reaction time is 0.8 h, the mass ratio of the catalyst to the molten glycolide is 0.0005:1, the outlet reaction conversion rate reaches 28%; the operating temperature of the around pipe reactor is 190℃, the operating pressure is 0.08 MPaG, the reaction time is 1.2 h, the cooling medium feed of the jacket and the winding pipe removes the polymerization reaction heat, the outlet reaction conversion rate reaches 80%; the operating temperature of the screw belt reactor is 220℃, the operating pressure is-0.05 MPaG, the reaction time is 1.2 h, the outlet reaction conversion rate reaches 80%, the final polyglycolide PGA product discharge amount is 1.25 t / h, the PGA product molecular weight is 188,000-198,000, and a good technical effect is achieved.

[0028] Example 2

[0029] The same as example 1, the production scale and operating conditions are changed, the polyglycolide PGA device production scale is 50,000 tons / year, the process parameters are modified as follows: the glycolide raw material feed amount is 8.82 t / h; the kettle type glycolide prepolymer kettle is provided with a disc type propeller structure type stirring paddle, the winding pipe of the around pipe reactor is 12 mm in diameter, the heat exchange area is 150 m 2 / m 3, the ratio of the diameter Dj of the screw stirring paddle to the inner diameter Di of the screw reactor is 0.98:1, and the rotating speed of the screw stirring paddle is 40 RPM; the operating temperature of the kettle-type glycolide prepolymer kettle is 188°C, the operating pressure is 0.3 MPaG, the reaction time is 0.9 h, the mass ratio of the catalyst to the molten glycolide is 0.0006:1, and the outlet reaction conversion rate reaches 30%; the operating temperature of the coiled tube reactor is 196°C, the operating pressure is 0.1 MPaG, the reaction time is 1.5 h, the jacket and the coiled tube are fed with cooling medium, i.e., heat transfer oil, to remove the polymerization heat, and the outlet reaction conversion rate reaches 82%; the operating temperature of the screw reactor is 237°C, the operating pressure is -0.08 MPaG, the reaction time is 1.7 h, and the outlet reaction conversion rate reaches 85%, and finally the output of the polyglycolide PGA product is 6.25 t / h, and the molecular weight of the PGA product is 172000-182000, thus achieving good technical effects.

[0030] Example 3

[0031] The production scale and operating conditions are changed as in Example 2, and the polyglycolide PGA device has a production scale of 100000 tons / year, and the process parameters are modified as follows: the feeding amount of the glycolide raw material is 20.00 t / h; the kettle-type glycolide prepolymer kettle is provided with a stirring paddle of the folding paddle impeller structure type, the coiled tube reactor is provided with a coiled tube with a tube diameter of 9 mm, and the heat exchange area is 190 m 2 / m 3 The screw reactor is provided with a single screw stirring paddle, the ratio of the diameter Dj of the screw stirring paddle to the inner diameter Di of the screw reactor is 0.93:1, and the rotating speed of the screw stirring paddle is 58 RPM; the operating temperature of the kettle-type glycolide prepolymer kettle is 120°C, the operating pressure is 0.0 MPaG, the reaction time is 0.3 h, the mass ratio of the catalyst to the molten glycolide is 0.0001:1, and the outlet reaction conversion rate reaches 15%; the operating temperature of the coiled tube reactor is 100°C, the operating pressure is 0.0 MPaG, the reaction time is 0.8 h, the jacket and the coiled tube are fed with cooling medium, i.e., heat transfer oil, to remove the polymerization heat, and the outlet reaction conversion rate reaches 65%; the operating temperature of the screw reactor is 120°C, the operating pressure is -0.10 MPaG, the reaction time is 0.5 h, and the outlet reaction conversion rate reaches 75%, and finally the output of the polyglycolide PGA product is 12.50 t / h, and the molecular weight of the PGA product is 200000-210000, thus achieving good technical effects.

[0032] Example 4

[0033] The same as example 2, the production scale and operation conditions are changed, the production scale of the polyglycolide PGA device is 100,000 tons / year, and the process parameters are modified as follows: the feeding amount of glycolide raw material is 15.79 t / h; the kettle type glycolide prepolymerization kettle is provided with a stirring paddle of inclined blade turbine structure type, the winding pipe of the around pipe type reactor is 10 mm in diameter, and the heat exchange area is 175 m 2 / m 3 The double screw stirring paddle is arranged in the screw belt type reactor, the ratio of the diameter Dj of the screw stirring paddle to the inner diameter Di of the screw belt type reactor is 0.94:1, the rotating speed of the screw stirring paddle is 52 RPM; the operating temperature of the kettle type glycolide prepolymerization kettle is 220℃, the operating pressure is 0.5 MPaG, the reaction time is 1.2 h, the mass ratio of catalyst to molten glycolide is 0.001:1, and the outlet reaction conversion rate reaches 35%; the operating temperature of the around pipe type reactor is 250℃, the operating pressure is 0.5 MPaG, the reaction time is 2.0 h, the cooling medium feeding oil is introduced into the jacket and the winding pipe to remove the polymerization heat, and the outlet reaction conversion rate reaches 85%; the operating temperature of the screw belt type reactor is 300℃, the operating pressure is 0.00 MPaG, the reaction time is 2.0 h, and the outlet reaction conversion rate reaches 95%, and finally the polyglycolide PGA product is obtained with an outlet feeding amount of 12.50 t / h, the molecular weight of the PGA product is 158,000-168,000, and a good technical effect is achieved.

[0034] Example 5

[0035] The same as example 1, the production scale and operation conditions are changed, the production scale of the polyglycolide PGA device is 200,000 tons / year, and two production lines are arranged. The process parameters are modified as follows: the feeding amount of glycolide raw material is 33.33 t / h; the kettle type glycolide prepolymerization kettle is provided with a stirring paddle of open straight blade turbine structure type, the winding pipe of the around pipe type reactor is 10 mm in diameter, and the heat exchange area is 175 m 2 / m 3, the ratio of the diameter Dj of the screw stirring paddle to the inner diameter Di of the screw reactor is 0.96:1, the rotating speed of the screw stirring paddle is 48 RPM; the operating temperature of the kettle-type glycolide prepolymer kettle is 200 ℃, the operating pressure is 0.2 MPaG, the reaction time is 1.0 h, the mass ratio of the catalyst to the molten glycolide is 0.0005:1, the outlet reaction conversion rate reaches 30%; the operating temperature of the coiled tube reactor is 190 ℃, the operating pressure is 0.2 MPaG, the reaction time is 1.0 h, the cooling medium feed of the jacket and the coiled tube is removed to take away the polymerization heat, the outlet reaction conversion rate reaches 80%; the operating temperature of the screw reactor is 200 ℃, the operating pressure is -0.07 MPaG, the reaction time is 1.0 h, the outlet reaction conversion rate reaches 90%, and finally the output of the polyglycolide PGA product is 25.00 t / h, the molecular weight of the PGA product is 160000-170000, and a good technical effect is achieved.

[0036] Example 6

[0037] The production scale and operating conditions are changed as in Example 1, the polyglycolide PGA device has a production scale of 300,000 tons / year, and three production lines are provided. The process parameters are modified as follows: the feed amount of the glycolide raw material is 50.00 t / h; the kettle-type glycolide prepolymer kettle is provided with a stirring paddle of a back-bending impeller structure type, the coiled tube reactor is provided with a coiled tube with a tube diameter of 11 mm, and the heat exchange area is 160 m 2 / m 3 The screw reactor is provided with a double-screw stirring paddle, the ratio of the diameter Dj of the screw stirring paddle to the inner diameter Di of the screw reactor is 0.97:1, the rotating speed of the screw stirring paddle is 44 RPM; the operating temperature of the kettle-type glycolide prepolymer kettle is 200 ℃, the operating pressure is 0.2 MPaG, the reaction time is 1.0 h, the mass ratio of the catalyst to the molten glycolide is 0.0005:1, the outlet reaction conversion rate reaches 30%; the operating temperature of the coiled tube reactor is 190 ℃, the operating pressure is 0.2 MPaG, the reaction time is 1.0 h, the cooling medium feed of the jacket and the coiled tube is removed to take away the polymerization heat, the outlet reaction conversion rate reaches 80%; the operating temperature of the screw reactor is 200 ℃, the operating pressure is -0.07 MPaG, the reaction time is 1.0 h, the outlet reaction conversion rate reaches 90%, and finally the output of the polyglycolide PGA product is 37.50 t / h, the molecular weight of the PGA product is 160000-170000, and a good technical effect is achieved.

Claims

1. A method for producing PGA using a continuous industrial production system for high molecular weight crude PGA, characterized by: The system comprises a first-stage polymerization reactor (1), a feed pump (2), a second-stage polymerization reactor (3), a third-stage polymerization reactor (4) and a product pump (5); the feed pump (2) is connected with the first-stage polymerization reactor (1) and the second-stage polymerization reactor (3) respectively, the third-stage polymerization reactor (4) is connected with the second-stage polymerization reactor (3) and the product pump (5) respectively, the first-stage polymerization reactor (1) is a kettle-type glycolide prepolymer kettle, the second-stage polymerization reactor (3) is a coiled tube reactor, the coiled tube reactor comprises a jacket and a coiled tube, and the third-stage polymerization reactor (4) is a screw belt reactor. The method comprises the following steps: a. the mixture (6) of molten glycolide and catalyst enters the first-stage polymerization reactor (1) to perform an adiabatic prepolymerization reaction, and a first-stage polymerization product (7) is obtained; b. the first-stage polymerization product (7) is pressurized by the feed pump (2) and then enters the second-stage polymerization reactor (3), the jacket and the coiled tube of the second-stage polymerization reactor (3) are connected with cooling medium feed 1 (10) and cooling medium feed 2 (12), the first-stage polymerization product (7) is further polymerized to obtain a second-stage polymerization product (9), and the cooling medium feed 1 (10) and the cooling medium feed 2 (12) are both heat-conducting oils; c. the second-stage polymerization product (9) enters the third-stage polymerization reactor (4), the third-stage polymerization reactor (4) is provided with an inactivator (14) and an antioxidant (15) at the bottom, the second-stage polymerization product (9) is subjected to an adiabatic polymerization reaction to obtain a crude PGA product (16) which is transported out of the system by the product pump (5), the inactivator (14) is sodium polysulfide, and the antioxidant (15) is one of propyl octadecanoate and phosphite.

2. The method of claim 1, wherein: The kettle-type glycolide prepolymer kettle is provided with a stirring paddle, and the stirring paddle has one of the following structural types: a propeller, a disc-type impeller, a folding paddle impeller, an inclined blade turbine, an open straight blade turbine and a back-bent impeller.

3. The method of claim 1, wherein: The pipe diameter of the winding pipe is 8-12 mm, and the heat exchange area is 150-200 m 2 / m 3 .

4. The method of claim 1, wherein: The screw belt reactor is provided with a screw belt stirring paddle, the screw belt stirring paddle has a single-screw belt structure or a double-screw belt structure, the ratio of the diameter Dj of the screw belt stirring paddle to the inner diameter Di of the screw belt reactor is 0.92-0.98:1, and the rotating speed of the screw belt stirring paddle is 40-60 RPM.

5. The method of claim 1, wherein: The operating temperature of the first polymerization reactor (1) in step a is 120-220℃, and the operating pressure is 0-0.5 MPaG; the time of the adiabatic prepolymerization is 0.3-1.2 h, and the conversion rate of the adiabatic prepolymerization is 15%-35%; the mass ratio of the catalyst to the molten glycolide is 0.0001-0.001:1; the operating temperature of the second polymerization reactor (3) in step b is 100-250℃, and the operating pressure is 0.0-0.5 MPaG; the time of the polymerization is 0.8-2.0 h, and the conversion rate of the polymerization is 65%-85%; the operating temperature of the third polymerization reactor (4) in step c is 120-300℃, and the operating pressure is -0.10-0.00 MPaG; the time of the adiabatic polymerization is 0.5-2.0 h, and the conversion rate of the adiabatic polymerization is 75%-95%.

6. The method of claim 5, wherein: The operating temperature of the first polymerization reactor (1) is 150-200℃, and the operating pressure is 0-0.3 MPaG; the time of the adiabatic prepolymerization is 0.5-1.0 h, and the conversion rate of the adiabatic prepolymerization is 20%-30%; the mass ratio of the catalyst to the molten glycolide is 0.0002-0.0006:1; the operating temperature of the second polymerization reactor (3) is 140-220℃, and the operating pressure is 0.0-0.3 MPaG; the time of the polymerization is 1.2-1.8 h, and the conversion rate of the polymerization is 70%-80%; the operating temperature of the third polymerization reactor (4) is 150-250℃, and the operating pressure is -0.10--0.07 MPaG; the time of the adiabatic polymerization is 0.8-1.5 h, and the conversion rate of the adiabatic polymerization is 80%-90%.

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