Apparatus for continuously producing polylactic acid polyol and method for producing the same

Abstract

The application discloses a device and a production method for continuously producing polylactic acid polyols, and the device comprises: a raw material mixing system for mixing lactide, polyols and a catalyst under inert environmental conditions; a preparation system connected with the raw material mixing system, which is used for mixing and reacting the lactide, the polyols and the catalyst to prepare a polylactic acid polyol crude product; and a purification system connected with the preparation system, through which the polylactic acid polyol crude product is prepared into a polylactic acid polyol. The device can adjust the reaction speed in three ways, has high flexibility and wide applicability, and provides an effective device and a production method for polylactic acid polyol industrial production. By adjusting the proportion and / or types of the lactide and the polyols, different types and / or different molecular weight products can be synthesized, so that the demand of polyurethane synthesis can be met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical industry, and particularly relates to a device for continuously producing polylactic acid polyol and a preparation method thereof. BACKGROUND

[0002] Biodegradable polyurethane is mainly prepared by copolymerization of biodegradable components such as polyether polyol or polyester polyol and diisocyanate or polyisocyanate. As a kind of polyester polyol, polylactic acid polyol has multiple hydroxyl groups on its structure, which can change the hydrophobicity of PLA to hydrophilicity, and can enhance the biocompatibility of the polymer. The polyurethane prepared by using polylactic acid polyol as raw material has good mechanical properties, and can be used for preparing elastomers, rigid-flexible foam, adhesives and coatings, and has a wide application prospect in the furniture, shoemaking, building and automobile industries.

[0003] At present, the main preparation method of polylactic acid polyol is as follows: lactide is used as the main raw material, polyol is used as the chain transfer agent, and the preparation is carried out by ring-opening polymerization under the action of a catalyst. By adjusting the proportion and / or type of lactide and polyol, polylactic acid polyol products of different types and / or different molecular weights can be synthesized. At present, there are obvious disadvantages in the preparation of polylactic acid polyol in a single kettle, such as: ① the efficiency of preparing polylactic acid polyol by using a batch reaction kettle is low, and the product quality is unstable between batches; ② the efficiency of devolatilization is low by using a batch single-kettle operation, and the product quality is poor. In order to meet the needs of polyurethane synthesis, at present, it is urgent to develop a more economical and efficient device and preparation method for preparing polylactic acid polyol. SUMMARY

[0004] In order to solve the above problems, the application provides a device and a preparation method for continuously producing polylactic acid polyol, which are simple to operate, have high synthesis efficiency, can adjust the reaction speed by three ways, have high flexibility and wide applicability.

[0005] In a first aspect, the application provides a device for continuously producing polylactic acid polyol, comprising:

[0006] A mixing system for mixing lactide, polyol and catalyst under inert environmental conditions;

[0007] A preparation system connected with the raw material mixing system, the preparation system is used for mixing and reacting the lactide, polyol and catalyst to prepare a polylactic acid polyol crude product;

[0008] A purification system connected with the preparation system, the polylactic acid polyol crude product is prepared into a polylactic acid polyol through the purification system.

[0009] According to some embodiments of the device of the present application, the raw material mixing system comprises a lactide raw material tank, a polyol raw material tank, a catalyst raw material tank, and a material mixing kettle, each of which is connected to the inert gas system, and each of the lactide raw material tank, the polyol raw material tank, and the catalyst raw material tank is connected to the material mixing kettle.

[0010] A feeding pump, a feeding flow meter, and a heat exchanger are arranged on the pipeline connecting the raw material tank and the material mixing kettle.

[0011] According to some embodiments of the device of the present application, the preparation system comprises a reactor, a heating system for heating the material in the reactor, and a pressure relief valve arranged at the top of the reactor.

[0012] According to some embodiments of the device of the present application, the number of the preparation systems is several, and the several preparation systems are connected in series.

[0013] The heating system used in the present application comprises a heating coil arranged in the reactor, and the heating coil is connected to a heating device.

[0014] According to some embodiments of the device of the present application, the purification system comprises a devolatilization kettle, a polylactic acid polyol storage tank, and a vacuum pump.

[0015] The feeding port of the devolatilization kettle is connected to the discharge port of the reactor, and a discharge pump, a discharge flow meter, and a heat exchanger are arranged on the pipeline connecting the feeding port of the devolatilization kettle and the discharge port of the reactor.

[0016] The discharge port of the devolatilization kettle is connected to the polylactic acid polyol storage tank, and a discharge pump and a discharge flow meter are arranged on the pipeline connecting the discharge port of the devolatilization kettle and the polylactic acid polyol storage tank.

[0017] According to some embodiments of the device of the present application, the purification system further comprises a monomer condenser and a monomer recovery tank, the monomer recovery tank is connected to the exhaust port of the devolatilization kettle, and a monomer condenser is arranged on the pipeline connecting the monomer recovery tank and the exhaust port of the devolatilization kettle.

[0018] In the second aspect of the present application, a method for producing polylactic acid polyol by using the device of the first aspect of the present application is provided, which comprises the following steps:

[0019] (1) uniformly stirring the preheated lactide, the polyol, and the catalyst under an inert environment;

[0020] (2) reacting the material obtained in step (1) under heating, and obtaining polylactic acid polyol by preheating and devolatilization under reduced pressure from the reaction liquid.

[0021] According to some embodiments of the method of the present application, in step (1), the mass ratio of the polyol and lactide is 1:(0.7-97); such as 1:0.7, 1:1, 1:2, 1:4, 1:4.63, 1:5.05, 1:10, 1:15, 1:18.6, 1:20, 1:30, 1:40, 1:48.92, 1:54.55, 1:60, 1:68, 1:73, 1:82, 1:90, 1:92, 1:97.

[0022] According to some embodiments of the method of the present application, the mass ratio of the polyol and lactide is 1:(4.63-54.55).

[0023] According to some embodiments of the method of the present application, the mass ratio of the polyol and lactide is 1:(4.63-48.92); such as 1:4.63, 1:5.05, 1:10, 1:15, 1:18.6, 1:20, 1:30, 1:40, 1:48.92.

[0024] According to some embodiments of the method of the present application, the preheating temperature of the lactide and polyol is 90-130°C; such as 90°C, 100°C, 110°C, 120°C, 130°C.

[0025] According to some embodiments of the method of the present application, the amount of the catalyst used is 0.01%-0.1% of the total mass of the lactide and polyol; such as 0.01%, 0.05%, 0.07%, 0.08%, 0.1%.

[0026] The feeding ratio of the lactide and polyol is adjusted according to the size of the desired product molecular weight.

[0027] According to some embodiments of the method of the present application, in step (1), the lactide is at least one of D-lactide, L-lactide, meso-lactide.

[0028] The polyol is at least one of aliphatic polyol, alicyclic polyol, or aromatic polyol.

[0029] According to some embodiments of the method of the present application, the aliphatic polyol is any one of ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, glycerol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, 3-methyl-1,5-pentanediol.

[0030] According to some embodiments of the method of the present application, the alicyclic polyol is any one of 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclododecane dimethanol, dodecycloalkanediol.

[0031] According to some embodiments of the method of the present application, the aromatic polyol is any one of hydroquinone dihydroxyethyl ether, resorcinol dihydroxyethyl ether, o-xylene glycol, m-xylene glycol, p-xylene glycol.

[0032] The catalyst is any one of neodymium iso-octoate, stannous octoate, lanthanum iso-octoate, stannous chloride, dibutyl tin dilaurate.

[0033] According to some embodiments of the method of the present application, in step (2), the temperature of the heating reaction is 80-180℃, such as 80℃, 90℃, 100℃, 110℃, 130℃, 150℃, 180℃, and the reaction time is 3-24h, such as 3h, 5h, 8h, 12h, 15h, 20h, 22h, 24h.

[0034] According to some embodiments of the method of the present application, the temperature of the heating reaction is 120-160℃, such as 120℃, 125℃, 130℃, 135℃, 140℃, 150℃, 160℃.

[0035] According to some embodiments of the method of the present application, in step (2), the reaction solution is heated to 150-180℃, such as 150℃, 155℃, 160℃, 170℃, 175℃, 180℃, and then is subjected to vacuum devolatilization.

[0036] The vacuum degree of the vacuum devolatilization is 100-1000pa, such as 100pa, 200pa, 300pa, 400pa, 500pa, 600pa, 700pa, 900pa, 1000pa, and the temperature of the vacuum devolatilization is 150-180℃, such as 150℃, 155℃, 160℃, 170℃, 175℃, 180℃.

[0037] The present application has the following advantages:

[0038] (1) The present application can adjust the reaction speed in three ways: way one is to keep the temperature and reaction time unchanged, change the catalyst addition ratio, and change the reaction speed; way two is to keep the catalyst addition ratio and reaction temperature unchanged, proportionally enlarge or reduce the feed flow, change the residence time of the material in the reactor, and change the reaction speed; way three is to keep the catalyst addition ratio and reaction time unchanged, change the reaction temperature, and change the reaction speed. The present application has high flexibility, wide applicability, and provides an effective device and production method for polylactic acid polyol industrial production.

[0039] (2) The device and its production method have the characteristics of simple operation, high synthesis efficiency, etc. Different types and / or different molecular weight of polylactic acid polyol products can be synthesized by adjusting the ratio and / or type of lactide and polyol to meet the needs of polyurethane synthesis. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 Figure 1 is a schematic diagram of the structure of the device for continuously producing polylactic acid polyol according to the embodiment 1 of the present application;

[0041] In the figure: 1, lactide raw material tank; 2, polyol raw material tank; 3, catalyst raw material tank; 4, material mixing kettle; 5, feed pump; 6, feed flow meter; 7, heat exchanger; 8, reactor; 9, heating system; 10, first pressure relief valve; 11, second pressure relief valve; 12, devolatilization kettle; 13, polylactic acid polyol storage tank; 14, vacuum pump; 15, discharge pump; 16, discharge flow meter; 17, monomer condenser; 18, monomer recovery tank. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below with reference to the embodiments and drawings. The specific embodiments described herein are only used to explain the present application and do not constitute any limitation on the present application. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present disclosure. Such structures and technologies are also described in many publications.

[0043] In actual operation, in order to prevent the oxygen and water vapor in the air in the raw material mixing system and the polylactic acid polyol preparation system from affecting the reaction degree and the color of the reaction solution, as a specific embodiment: open the pipeline valves of the raw material mixing system and the polylactic acid polyol preparation system, use the vacuum system to extract the air in the raw material mixing system and the polylactic acid polyol preparation system, then use the nitrogen system to flush nitrogen into the lactide raw material tank, the polyol raw material tank, the catalyst raw material tank and the material mixing kettle to replace the air in the raw material mixing system and the polylactic acid polyol preparation system, repeat the above operation three times, close the pipeline valves, and the device is ready for use.

[0044] In order to prevent the material from solidifying in the pipeline, the material pipelines of the raw material mixing system, the polylactic acid polyol preparation system and the polylactic acid polyol purification system are provided with insulation jackets.

[0045] Embodiment 1

[0046] A device for continuously producing polylactic acid polyol, comprising: a raw material mixing system for mixing lactide, polyol and catalyst under inert environmental conditions;

[0047] A preparation system connected with the raw material mixing system, the preparation system is used for mixing and reacting the lactide, the polyol and the catalyst to obtain the polylactic acid polyol crude product;

[0048] A purification system connected with the preparation system, the polylactic acid polyol crude product is obtained by the polylactic acid polyol through the purification system.

[0049] The raw material mixing system used in the embodiment includes a lactide raw material tank 1, a polyol raw material tank 2, a catalyst raw material tank 3 and a material mixing kettle 4, which are connected with the inert gas system; the lactide raw material tank 1, the polyol raw material tank 2 and the catalyst raw material tank 3 are connected with the material mixing kettle 4; and the pipelines connecting the raw material tanks and the material mixing kettle 4 are provided with a feeding pump 5, a feeding flow meter 6 and a heat exchanger 7.

[0050] The preparation system used in the embodiment includes a reactor 8, a heating system 9 used for heating the material in the reactor 8 (a heating coil is arranged in the reactor 8, and the coil is connected with the heating system 9), and a pressure relief valve arranged at the top of the reactor 8; the number of the preparation system is 3, and the three preparation systems are connected in series.

[0051] The purification system used in the embodiment includes a devolatilization kettle 12 (the devolatilization kettle 12 is provided with a material distributor), a polylactic acid polyol storage tank 13 and a vacuum pump 14; the feeding port of the devolatilization kettle 12 is connected with the discharging port of the reactor 8, and the pipeline connecting the feeding port of the devolatilization kettle 12 and the discharging port of the reactor 8 is provided with a discharging pump 15, a discharging flow meter 16 and a heat exchanger 7; the discharging port of the devolatilization kettle 12 is connected with the polylactic acid polyol storage tank 13, and the pipeline connecting the discharging port of the devolatilization kettle 12 and the polylactic acid polyol storage tank 13 is provided with a discharging pump 15 and a discharging flow meter 16.

[0052] The exhaust port of the devolatilization kettle 12 is connected with a monomer recovery tank 18, and the pipeline connecting the monomer recovery tank 18 and the devolatilization kettle 12 is provided with a monomer condenser 17; the reaction liquid is distributed by the distributor to remove a small amount of unreacted monomers in the polylactic acid polyol crude product, and the gaseous monomers are condensed by the monomer condenser 17 and then enter the monomer recovery tank 18 for recycling.

[0053] Embodiment 2

[0054] Embodiment 2 provides a method for producing the polylactic acid polyol by using the device described in embodiment 1, specifically:

[0055] The raw material tank is kept under a slight positive pressure using a nitrogen system. The corresponding raw materials are added and then the solid raw materials are melted by heating. The raw material mixing system and the polylactic acid polyol preparation system are opened. The reaction liquid outlet pipeline valve is slightly opened. The L-lactide feeding pump, the ethylene glycol feeding pump and the neodymium iso-octoate feeding pump are started. The L-lactide feeding flowmeter and the ethylene glycol feeding flowmeter are observed. The frequency of the L-lactide feeding pump and the ethylene glycol feeding pump is adjusted so that the mass flow rate of the L-lactide feeding is 105.11 kg / h and the mass flow rate of the ethylene glycol feeding is 14.89 kg / h. The neodymium iso-octoate feeding flowmeter is observed. The frequency of the neodymium iso-octoate feeding pump is adjusted so that the mass flow rate of the neodymium iso-octoate feeding is 120.0 g / h. The L-lactide and the ethylene glycol are preheated to 90-100°C by the heat exchanger 7 and are mixed with the neodymium iso-octoate in the material mixing kettle 4 by mechanical stirring.

[0056] The polylactic acid polyol preparation system: the reaction liquid outlet pipeline valve is closed. The first pressure relief valve 10 is opened. The L-lactide, the ethylene glycol and the neodymium iso-octoate mixed liquid flows from the side of the material mixing kettle 4 to the reactor 8. Nitrogen is discharged from the top of the reactor 8. When the reaction liquid reaches the top of the reactor 8, the second pressure relief valve 11 is opened and the first pressure relief valve 10 is closed. The heating system 9 is started in sequence. The temperature of the reaction liquid is kept at 120-130°C by the coil in the reactor 8. The reaction is carried out for 5 hours. When the reactor 8 is filled with the reaction liquid, the reaction liquid pipeline valve is opened. The reaction liquid outlet pump is started. The pressure relief valves are closed.

[0057] The polylactic acid polyol purification system: the reaction liquid outlet flowmeter 16 is observed. The frequency of the reaction liquid outlet pump is adjusted so that the mass flow rate of the reaction liquid outlet is 120.00 kg / h. The reaction liquid is heated to 150-160°C by the heat exchanger 7 and is fed into the devolatilization kettle 12. The devolatilization kettle 12 is vacuumized to 100-500 pa by the vacuum pump 14. The reaction liquid is distributed by the distributor for devolatilization. The gaseous phase monomer is condensed by the condenser and is fed into the monomer recovery tank 18 for recycling. The finished polylactic acid polyol outlet pump is started. The frequency of the finished polylactic acid polyol outlet pump is adjusted. The polylactic acid polyol after devolatilization is fed into the finished polylactic acid polyol storage tank 13 by the outlet pump while keeping the liquid level of the polylactic acid polyol in the devolatilization kettle 12.

[0058] Example 3

[0059] Example 3 provides a method for producing polylactic acid polyol using the device described in Example 1. Specifically, the method comprises the following steps:

[0060] The raw material tank is kept under a slight positive pressure using a nitrogen system. The corresponding raw materials are added and then the solid raw materials are melted by heating. The raw material mixing system and the polylactic acid polyol preparation system are opened. The reaction liquid outlet pipeline valve is slightly opened. The L-lactide feeding pump, the 1,4-butanediol feeding pump, and the stannous octoate feeding pump are started. The L-lactide feeding flowmeter and the 1,4-butanediol feeding flowmeter are observed. The frequency of the L-lactide feeding pump and the 1,4-butanediol feeding pump is adjusted so that the mass flow rate of the L-lactide feeding is 49.10 kg / h and the mass flow rate of the 1,4-butanediol feeding is 0.90 kg / h. The stannous octoate feeding flowmeter is observed. The frequency of the stannous octoate feeding pump is adjusted so that the mass flow rate of the stannous octoate feeding is 10.0 g / h. The L-lactide and the 1,4-butanediol are preheated to 110-120°C by the heat exchanger 7 and are mixed with the stannous octoate in the material mixing kettle 4 by mechanical stirring.

[0061] The polylactic acid polyol preparation system: the reaction liquid outlet pipeline valve is closed. The first pressure relief valve 10 is opened. The L-lactide, the 1,4-butanediol, and the stannous octoate mixed liquid overflow from the side of the material mixing kettle 4 into the reactor 8. Nitrogen is discharged from the top of the reactor 8. When the reaction liquid reaches the top of the reactor 8, the second pressure relief valve 11 is opened and the first pressure relief valve 10 is closed. The heating system 9 is sequentially operated while being turned on to keep the temperature of the reaction liquid at 150-160°C by the coil in the reactor 8 for 12 h. When the reactor 8 is filled with the reaction liquid, the reaction liquid pipeline valve is opened. The reaction liquid discharge pump is started. The pressure relief valve is closed.

[0062] The polylactic acid polyol purification system: the reaction liquid discharge flowmeter 16 is observed. The frequency of the reaction liquid discharge pump is adjusted so that the mass flow rate of the reaction liquid discharge is 50.00 kg / h. The reaction liquid is heated to 160-170°C by the heat exchanger 7 and then enters the devolatilization kettle 12. The devolatilization kettle 12 is vacuumized to 500-1000 pa by using the vacuum pump 14. The reaction liquid is distributed by the distributor for devolatilization. The gaseous monomer is condensed by the monomer condenser 17 and then enters the monomer recovery tank 18 for recycling. The finished polylactic acid polyol discharge pump is started. The frequency of the finished polylactic acid polyol discharge pump is adjusted. Under the condition that the liquid level of the polylactic acid polyol in the devolatilization kettle 12 is maintained, the devolatilized polylactic acid polyol enters the finished polylactic acid polyol storage tank 13 by the discharge pump.

[0063] Example 4

[0064] Example 4 provides a method for producing polylactic acid polyol using the device described in Example 1. Specifically, the method comprises the following steps:

[0065] The raw material tank is kept under a slight positive pressure using a nitrogen system. The corresponding raw materials are added and then the solid raw materials are melted by heating. The raw material mixing system and the polylactic acid polyol preparation system are opened. The reaction liquid outlet pipeline valve is slightly opened. The L-lactide feed pump, the trimethylolpropane feed pump and the stannous chloride feed pump are started. The L-lactide feed flowmeter and the trimethylolpropane feed flowmeter are observed. The frequency of the L-lactide feed pump and the trimethylolpropane feed pump is adjusted so that the mass flow rate of the L-lactide feed is 69.97 kg / h and the mass flow rate of the trimethylolpropane feed is 5.03 kg / h. The stannous chloride feed flowmeter is observed. The frequency of the stannous chloride feed pump is adjusted so that the mass flow rate of the stannous chloride feed is 56.3 g / h. The preheated L-lactide and trimethylolpropane are mixed with the stannous chloride in the material mixing kettle 4 by mechanical stirring.

[0066] The polylactic acid polyol preparation system: the reaction liquid outlet pipeline valve is closed. The first pressure relief valve 10 is opened. The L-lactide, trimethylolpropane and stannous chloride mixture flows from the side of the material mixing kettle 4 to the reactor 8. Nitrogen is discharged from the top of the reactor 8. When the reaction liquid reaches the top of the reactor 8, the second pressure relief valve 11 is opened and the first pressure relief valve 10 is closed. The heating system 9 is sequentially operated while the temperature of the reaction liquid is maintained at 140-150°C by the coil in the reactor 8. When the reactor 8 is filled with the reaction liquid, the reaction liquid pipeline valve is opened and the reaction liquid discharge pump is started. The pressure relief valve is closed.

[0067] The polylactic acid polyol purification system: the reaction liquid discharge flowmeter 16 is observed. The frequency of the reaction liquid discharge pump is adjusted so that the mass flow rate of the reaction liquid discharge is 75.00 kg / h. The reaction liquid is heated to 150-160°C by the heat exchanger 7 and then enters the devolatilization kettle 12. The devolatilization kettle 12 is vacuumized to 100-500 pa by the vacuum pump 14. The reaction liquid is distributed by the distributor and devolatilized. The gaseous monomer is condensed by the monomer condenser 17 and then enters the monomer recovery tank 18 for recycling. The finished polylactic acid polyol discharge pump is started. The frequency of the finished polylactic acid polyol discharge pump is adjusted. The devolatilized polylactic acid polyol enters the finished polylactic acid polyol storage tank 13 by the discharge pump while the liquid level of the polylactic acid polyol in the devolatilization kettle 12 is maintained.

[0068] Example 5

[0069] Example 5 provides a method for producing polylactic acid polyol using the device described in Example 1. Specifically, the method comprises the following steps:

[0070] The raw material tank is kept under a slight positive pressure using a nitrogen system. The corresponding raw materials are added and the solid raw materials are melted by heating. The raw material mixing system and the polylactic acid polyol preparation system are opened. The reaction liquid outlet pipeline valve is slightly opened. The L-lactide feed pump, the o-phenylenedimethanol feed pump, and the dibutyltin dilaurate feed pump are started. The L-lactide feed flowmeter and the o-phenylenedimethanol feed flowmeter are observed. The frequency of the L-lactide feed pump and the o-phenylenedimethanol feed pump is adjusted so that the mass flow rate of the L-lactide feed is 48.28 kg / h and the mass flow rate of the o-phenylenedimethanol feed is 1.72 kg / h. The dibutyltin dilaurate feed flowmeter is observed. The frequency of the dibutyltin dilaurate feed pump is adjusted so that the mass flow rate of the dibutyltin dilaurate feed is 10.0 g / h. The L-lactide and the o-phenylenedimethanol are preheated to 120-130°C by the heat exchanger 7. The mixture of the L-lactide, the o-phenylenedimethanol, and the dibutyltin dilaurate is mixed uniformly in the material mixing kettle 4 by mechanical stirring.

[0071] The polylactic acid polyol preparation system: the reaction liquid outlet pipeline valve is closed. The first pressure relief valve 10 is opened. The mixture of the L-lactide, the o-phenylenedimethanol, and the dibutyltin dilaurate flows from the side of the material mixing kettle 4 to the reactor 8. Nitrogen is discharged from the top of the reactor 8. When the reaction liquid reaches the top of the reactor 8, the second pressure relief valve 11 is opened and the first pressure relief valve 10 is closed. The heating system 9 is started to keep the temperature of the reaction liquid at 140-150°C in the reactor 8. The reaction is carried out for 12 hours. When the reactor 8 is filled with the reaction liquid, the reaction liquid pipeline valve is opened. The reaction liquid outlet pump is started. The pressure relief valve is closed.

[0072] The polylactic acid polyol purification system: the reaction liquid outlet flowmeter 16 is observed. The frequency of the reaction liquid outlet pump is adjusted so that the mass flow rate of the reaction liquid outlet is 50.0 kg / h. The reaction liquid is heated to 160-170°C by the heat exchanger 7 and then enters the devolatilization kettle 12. The devolatilization kettle 12 is vacuumized to 500-1000 pa by the vacuum pump 14. The reaction liquid is distributed by the distributor and devolatilized. The gaseous monomer is condensed by the monomer condenser 17 and then enters the monomer recovery tank 18 for recycling. The finished polylactic acid polyol outlet pump is started. The frequency of the finished polylactic acid polyol outlet pump is adjusted. The devolatilized polylactic acid polyol enters the finished polylactic acid polyol storage tank 13 by the outlet pump while keeping the liquid level of the polylactic acid polyol in the devolatilization kettle 12.

[0073] Example 6

[0074] Example 6 provides a method for producing polylactic acid polyol using the device described in Example 1. Specifically, the method comprises the following steps:

[0075] The raw material tank is kept under a slight positive pressure using a nitrogen system. The corresponding raw materials are added and the solid raw materials are melted by heating. The raw material mixing system and the polylactic acid polyol preparation system are opened. The reaction liquid outlet pipeline valve is slightly opened. The D-lactide feed pump, the 1,2-cyclohexanediol feed pump, and the lanthanum iso-octoate feed pump are started. The D-lactide feed flowmeter and the 1,2-cyclohexanediol feed flowmeter are observed. The frequency of the D-lactide feed pump and the 1,2-cyclohexanediol feed pump is adjusted so that the mass flow of the D-lactide feed is 57.33 kg / h and the mass flow of the 1,2-cyclohexanediol feed is 2.67 kg / h. The lanthanum iso-octoate feed flowmeter is observed. The frequency of the lanthanum iso-octoate feed pump is adjusted so that the mass flow of the lanthanum iso-octoate feed is 30.0 g / h. The D-lactide and the 1,2-cyclohexanediol are preheated to 120-130°C by the heat exchanger 7. The mixture of the D-lactide, the 1,2-cyclohexanediol, and the lanthanum iso-octoate is mixed uniformly in the material mixing kettle 4 by mechanical stirring.

[0076] The polylactic acid polyol preparation system: the reaction liquid outlet pipeline valve is closed. The first pressure relief valve 10 is opened. The mixture of the D-lactide, the 1,2-cyclohexanediol, and the lanthanum iso-octoate flows from the side of the material mixing kettle 4 to the reactor 8. Nitrogen is discharged from the top of the reactor 8. When the reaction liquid reaches the top of the reactor 8, the second pressure relief valve 11 is opened and the first pressure relief valve 10 is closed. The heating system 9 is started to keep the temperature of the reaction liquid at 150-160°C by the coil in the reactor 8. The reaction is carried out for 10 hours. When the reactor 8 is filled with the reaction liquid, the reaction liquid pipeline valve is opened. The reaction liquid outlet pump is started. The pressure relief valve is closed.

[0077] The polylactic acid polyol purification system: the reaction liquid outlet flowmeter 16 is observed. The frequency of the reaction liquid outlet pump is adjusted so that the mass flow of the reaction liquid outlet is 60.00 kg / h. The reaction liquid is heated to 150-160°C by the heat exchanger 7 and then enters the devolatilization kettle 12. The devolatilization kettle 12 is vacuumized to 100-500 pa by the vacuum pump 14. The reaction liquid is distributed by the distributor for devolatilization. The gaseous monomer is condensed by the monomer condenser 17 and then enters the monomer recovery tank 18 for recycling. The finished polylactic acid polyol outlet pump is started. The frequency of the finished polylactic acid polyol outlet pump is adjusted. The devolatilized polylactic acid polyol enters the finished polylactic acid polyol storage tank 13 by the outlet pump while keeping the liquid level of the polylactic acid polyol in the devolatilization kettle 12.

[0078] Example 7

[0079] Example 7 provides a method for producing polylactic acid polyol using the device described in Example 1. Specifically, the method comprises the following steps:

[0080] The raw material tank is kept under a slight positive pressure using a nitrogen system. The corresponding raw materials are added and then the solid raw materials are melted by heating. The raw material mixing system and the polylactic acid polyol preparation system are opened. The reaction liquid outlet pipeline valve is slightly opened. The meso-lactide feeding pump, the 1,3-propanediol feeding pump, and the stannous octoate feeding pump are opened. The meso-lactide feeding flowmeter and the 1,3-propanediol feeding flowmeter are observed. The frequency of the meso-lactide feeding pump and the 1,3-propanediol feeding pump is adjusted so that the mass flow rate of the meso-lactide feeding is 110.88 kg / h and the mass flow rate of the 1,3-propanediol feeding is 9.12 kg / h. The stannous octoate feeding flowmeter is observed. The frequency of the stannous octoate feeding pump is adjusted so that the mass flow rate of the stannous octoate feeding is 120.0 g / h. The meso-lactide and the 1,3-propanediol are preheated to 90-100℃ by the heat exchanger 7. The mixture of the meso-lactide, the 1,3-propanediol, and the stannous octoate enters the material mixing kettle 4 and is uniformly mixed by mechanical stirring.

[0081] The polylactic acid polyol preparation system: the reaction liquid outlet pipeline valve is closed. The first pressure relief valve 10 is opened. The mixture of the meso-lactide, the 1,3-propanediol, and the stannous octoate flows from the side of the material mixing kettle 4 to the reactor 8. Nitrogen is discharged from the top of the reactor 8. When the reaction liquid reaches the top of the reactor 8, the second pressure relief valve 11 is opened. The pressure relief valve is closed. The heating system 9 is sequentially operated while being opened. The temperature of the reaction liquid is maintained at 120-130℃ by the coil in the reactor 8. The reaction is carried out for 5 h. When the reactor 8 is filled with the reaction liquid, the reaction liquid pipeline valve is opened. The reaction liquid discharge pump is opened. The pressure relief valve is closed.

[0082] The polylactic acid polyol purification system: the reaction liquid discharge flowmeter 16 is observed. The frequency of the reaction liquid discharge pump is adjusted so that the mass flow rate of the reaction liquid discharge is 120.00 kg / h. The reaction liquid is heated to 160-170℃ by the heat exchanger 7 and then enters the devolatilization kettle 12. The devolatilization kettle 12 is vacuumized to 500-1000 pa using the vacuum pump 14. The reaction liquid is distributed by the distributor for devolatilization. The gaseous monomer is condensed by the monomer condenser 17 and then enters the monomer recovery tank 18 for recycling. The finished polylactic acid polyol discharge pump is opened. The frequency of the finished polylactic acid polyol discharge pump is adjusted. The devolatilized polylactic acid polyol enters the finished polylactic acid polyol storage tank 13 while maintaining the liquid level of the polylactic acid polyol in the devolatilization kettle 12.

[0083] Example 8

[0084] Example 8 provides a method for producing polylactic acid polyol using the device described in Example 1. Specifically, the method comprises the following steps:

[0085] The raw material tank is kept under a slight positive pressure using a nitrogen system. The corresponding raw materials are fed in and the solid raw materials are then melted by heating. The raw material mixing system and the polylactic acid polyol preparation system are opened, the reaction liquid outlet pipeline valve is kept slightly open, the L-lactide feeding pump, the ethylene glycol feeding pump and the stannous octoate feeding pump are started, the L-lactide feeding flowmeter and the ethylene glycol feeding flowmeter are observed, the frequency of the L-lactide feeding pump and the ethylene glycol feeding pump is adjusted so that the mass flow rate of the L-lactide feeding is 49.49 kg / h and the mass flow rate of the ethylene glycol feeding is 0.51 kg / h, the stannous octoate feeding flowmeter is observed, and the frequency of the stannous octoate feeding pump is adjusted so that the mass flow rate of the stannous octoate feeding is 10.0 g / h. The preheated L-lactide and ethylene glycol are mixed with the stannous octoate in the material mixing kettle 4 by mechanical stirring.

[0086] The polylactic acid polyol preparation system: the reaction liquid outlet pipeline valve is closed, the first pressure relief valve 10 is opened, the L-lactide, ethylene glycol and stannous octoate mixed liquid flows from the side of the material mixing kettle 4 to the reactor 8, nitrogen is discharged from the top of the reactor 8, when the reaction liquid reaches the top of the reactor 8, the second pressure relief valve 11 is opened and the first pressure relief valve 10 is closed, the heating system 9 is sequentially operated to keep the temperature of the reaction liquid in the reactor 8 at 150-160°C, and the reaction is carried out for 12 h. When the reactor 8 is filled with the reaction liquid, the reaction liquid pipeline valve is opened, the reaction liquid outlet pump is started, and the pressure relief valve is closed.

[0087] The polylactic acid polyol purification system: the reaction liquid outlet flowmeter 16 is observed, the frequency of the reaction liquid outlet pump is adjusted so that the mass flow rate of the reaction liquid outlet is 50.00 kg / h, the reaction liquid is heated to 160-170°C by the heat exchanger 7, then enters the devolatilization kettle 12, and the devolatilization kettle 12 is vacuumized to 500-1000 pa by the vacuum pump 14. The reaction liquid is distributed by the distributor and devolatilized, the gaseous monomer is condensed by the monomer condenser 17 and then enters the monomer recovery tank 18 for recycling, the finished polylactic acid polyol outlet pump is started, and the frequency of the finished polylactic acid polyol outlet pump is adjusted. Under the condition that the liquid level of the polylactic acid polyol in the devolatilization kettle 12 is maintained, the devolatilized polylactic acid polyol enters the finished polylactic acid polyol storage tank 13 through the outlet pump.

[0088] Example 9

[0089] Example 9 provides a method for producing polylactic acid polyol using the device described in Example 1, specifically:

[0090] The raw material tank is kept under a slight positive pressure by using a nitrogen system. The corresponding raw materials are respectively fed in and then the solid raw materials are melted by heating. The raw material mixing system and the polylactic acid polyol preparation system pipeline valves are opened, the reaction liquid outlet pipeline valve is slightly opened, the L-lactide feeding pump, the dodecycloalkanediol feeding pump and the neodymium iso-octoate feeding pump are started, the L-lactide feeding flowmeter and the dodecycloalkanediol feeding flowmeter are observed, the frequency of the L-lactide feeding pump and the dodecycloalkanediol feeding pump is adjusted so that the mass flow of the L-lactide feeding is 83.72 kg / h and the mass flow of the dodecycloalkanediol feeding is 116.28 kg / h, the neodymium iso-octoate feeding flowmeter is observed, and the frequency of the neodymium iso-octoate feeding pump is adjusted so that the mass flow of the neodymium iso-octoate feeding is 200.0 g / h. The L-lactide and the dodecycloalkanediol are preheated to 120-130 DEG C by the heat exchanger 7 and are mixed with the neodymium iso-octoate in the material mixing kettle 4 by mechanical stirring.

[0091] The polylactic acid polyol preparation system: the reaction liquid outlet pipeline valve is closed, the first pressure relief valve 10 is opened, the L-lactide, dodecycloalkanediol and neodymium iso-octoate mixed liquid flows from the side of the material mixing kettle 4 to the reactor 8, nitrogen is discharged from the top of the reactor 8, when the reaction liquid reaches the top of the reactor 8, the second pressure relief valve 11 is opened and the first pressure relief valve 10 is closed, the heating system 9 is sequentially operated and started to keep the temperature of the reaction liquid in the reactor 8 at 130-140 DEG C by the coil in the reactor 8 for 3 h, when the reactor 8 is filled with the reaction liquid, the reaction liquid pipeline valve is opened, the reaction liquid outlet pump is started, and the pressure relief valve is closed.

[0092] The polylactic acid polyol purification system: the reaction liquid outlet flowmeter 16 is observed, the frequency of the reaction liquid outlet pump is adjusted so that the mass flow of the reaction liquid outlet is 200.00 kg / h, the reaction liquid is heated to 150-160 DEG C by the heat exchanger 7 and is fed into the devolatilization kettle 12, the devolatilization kettle 12 is simultaneously vacuumized to 100-500 pa by using the vacuum pump 14, the reaction liquid is distributed by the distributor for devolatilization, the gaseous phase monomer is condensed by the condenser and is fed into the monomer recovery tank 18 for recycling, the finished polylactic acid polyol outlet pump is started, the frequency of the finished polylactic acid polyol outlet pump is adjusted, and the polylactic acid polyol after devolatilization is fed into the finished polylactic acid polyol storage tank 13 by the outlet pump under the condition that the liquid level of the polylactic acid polyol in the devolatilization kettle 12 is kept.

[0093] The physical parameters of the polylactic acid polyols obtained in the examples 2 to 7 of the present application are shown in Table 1.

[0094] Table 1

[0095]

[0096]

[0097] Note: The molecular weight of the embodiments of the present application is determined by nuclear magnetic resonance and calculated, the molecular weight distribution is determined by gel permeation chromatography and calculated, and the acid value and hydroxyl value are determined by titration and calculated.

[0098] As can be seen from Table 1, the data of the molecular weight determined by nuclear magnetic resonance and the acid value and the indirectly calculated molecular weight can show that the different types and / or different molecular weight polylactic acid polyols can be successfully and continuously prepared in a high efficiency by adjusting the raw material ratio and / or the raw material type according to the requirements by using the device of the present application.

[0099] As can be seen from Table 1, the polylactic acid polyols prepared by the preparation method of the present application have a narrow molecular weight distribution width and a low acid value, which shows that the influence of water on the acid value can be effectively reduced by using the device of the present application, the polylactic acid polyols prepared have a low acid value and a good quality; and the reaction can be well controlled (such as the reaction time, the reaction temperature, etc.) by using the device of the present application, the polylactic acid polyols prepared have a narrow molecular weight distribution width and a good quality.

[0100] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that each technical feature is combined in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the present application and belong to the protection scope of the present application.

Claims

1. A device for continuously producing polylactic acid polyol, comprising: a mixing system for mixing lactide, polyol and catalyst under inert environment; a preparation system connected to the mixing system, the preparation system being used for mixing and reacting the lactide, polyol and catalyst to produce polylactic acid polyol crude product; a purification system connected to the preparation system, the polylactic acid polyol crude product being purified by the purification system to produce polylactic acid polyol; the mixing system comprises a lactide raw material tank, a polyol raw material tank, a catalyst raw material tank and a material mixing kettle, each of the lactide raw material tank, the polyol raw material tank and the catalyst raw material tank being connected to the material mixing kettle; a pipeline connecting the raw material tank and the material mixing kettle is provided with a feeding pump, a feeding flow meter and a heat exchanger; the preparation system comprises a reactor, a heating system for heating the material in the reactor and a pressure relief valve arranged at the top of the reactor; the purification system comprises a devolatilization kettle, a polylactic acid polyol storage tank and a vacuum pump; a feeding port of the devolatilization kettle is connected to a discharging port of the reactor, a pipeline connecting the feeding port of the devolatilization kettle and the discharging port of the reactor is provided with a discharging pump, a discharging flow meter and a heat exchanger; a discharging port of the devolatilization kettle is connected to the polylactic acid polyol storage tank, a pipeline connecting the discharging port of the devolatilization kettle and the polylactic acid polyol storage tank is provided with a discharging pump and a discharging flow meter; the number of the preparation system is several, and the several preparation systems are connected in series; the purification system further comprises a monomer condenser and a monomer recovery tank, the monomer recovery tank being connected to an exhaust port of the devolatilization kettle, a pipeline connecting the monomer recovery tank and the exhaust port of the devolatilization kettle being provided with the monomer condenser; the device comprises the following steps: (1) uniformly mixing preheated lactide, polyol and catalyst under inert environment; (2) reacting the material obtained in step (1) under heating, and obtaining polylactic acid polyol by preheating and devolatilization under reduced pressure. In step (1), the mass ratio of the polyol to the lactide is 1:(0.7-97). In step (1), the mass ratio of the polyol to the lactide is 1:(4.63-54.55). In step (1), the mass ratio of the polyol to the lactide is 1:(4.63-48.92). The preheating temperature of the lactide and the polyol is 90-130℃. The amount of the catalyst is 0.01%-0.1% of the total mass of the lactide and the polyol. In step (1), the lactide is at least one of D-lactide, L-lactide and meso-lactide. The polyol is at least one of aliphatic polyol, alicyclic polyol and aromatic polyol. The aliphatic polyol is any one of ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, glycerol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol and trimethylolpropane. ​ 2. The apparatus for continuously producing polylactic acid polyol according to claim 1, wherein ​ 3. The apparatus for continuously producing polylactic acid polyol according to claim 1, wherein ​ 4. A method for producing polylactic acid polyol using the apparatus according to any one of claims 1 to 3, characterized by, ​ ​ ​ 5. The method of claim 4, wherein, ​ 6. The method of claim 4, wherein, ​ 7. The method of claim 4, wherein, ​ 8. The method of claim 4, wherein, ​ 9. The method of claim 4, wherein, ​ 10. The method of claim 4, wherein, ​ ​ 11. The method of claim 10, wherein, ​ 12. The method of claim 10, wherein, The alicyclic polyol is any one of 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclododecane dimethanol, dodecylophanediol.

13. The method of claim 10, wherein, The aromatic polyol is any one of hydroquinone dihydroxyethyl ether, resorcinol dihydroxyethyl ether, o-xylyl alcohol, m-xylyl alcohol, p-xylyl alcohol; The catalyst is any one of neodymium isooctoate, stannous octoate, lanthanum isooctoate, stannous chloride, dibutyl tin dilaurate.

14. The method of claim 4, wherein, In step (2), the heating temperature is 80-180℃, and the reaction time is 3-24h.

15. The method of claim 4, wherein, The heating temperature is 120-160℃.

16. The method of claim 4, wherein, In step (2), the reaction solution is heated to 150-180℃, and then subjected to vacuum devolatilization. The vacuum degree of the vacuum devolatilization is 100-1000pa, and the temperature of the vacuum devolatilization is 150-180℃.

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