Lactide / glycolide copolymer production system

Abstract

The utility model belongs to the technical field of chemical engineering, and particularly relates to a lactide / glycolide copolymer production system, which comprises a mixing device, a prepolymerization reactor, a polymerization reactor and an end-capped devolatilization device which are sequentially communicated along the reaction direction, a feeding hole of the mixing device is communicated with a falling film crystallizer, and the falling film crystallizer is provided with a feeding hole, a cold and hot coal inlet and a mixing device. By additionally arranging the falling film crystallizer communicated with the feeding hole of the mixing device, Meso-lactide can be effectively removed, so that the purity of the prepared lactide / glycolide copolymer is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of chemical production equipment, and specifically discloses a lactide / glycolide copolymer production system. Background Art

[0002] Lactide / glycolide copolymer (PLGA), also known as polyglycolide / lactide copolymer, has the advantages of safety, reliability, good biocompatibility, and controllable biodegradability. It is widely used in surgical sutures, anti-adhesion membranes, tissue engineering scaffolds, absorbable microspheres (such as drug-loaded sustained-release microspheres) and other fields.

[0003] Generally, by controlling the ratio of lactide monomer to glycolide monomer, lactide / glycolide copolymers with different properties can be prepared. The degree of degradation of lactide / glycolide copolymers varies with the ratio of lactide monomer to glycolide monomer. Generally, the greater the ratio of glycolide, the easier the lactide / glycolide copolymer is to degrade. Since lactide / glycolide copolymers are random copolymers and the factors affecting the polymerization effect are more complex, the control of the chain structure is the key to the lactide / glycolide copolymer polymerization process system. Most of the existing lactide / glycolide copolymer production devices can only achieve solution polymerization or small-batch bulk polymerization, and cannot achieve large-scale production of PLGA copolymers.

[0004] In order to solve the above technical problems, the patent document with publication number CN216172365U discloses a system for continuously synthesizing PLGA copolymers, including a prepolymerization reactor, a second monomer mixer, a polymerization reactor, and an end-capping devolatilizer arranged in sequence along the reaction direction, the prepolymerization reactor is a place where the first monomer is ring-opened polymerized to form a first monomer prepolymer through a prepolymerization reaction, the second monomer mixer is a place where the first monomer prepolymer and the second monomer are mixed and ring-opened polymerized to form a first monomer-second monomer block copolymer, the polymerization reactor is a place where the first monomer-second monomer block copolymer is further polymerized to further increase the molecular weight, and the end-capping devolatilizer is a place where the first monomer and the second monomer block copolymer are subjected to an end-capping devolatilization reaction after the polymerization reaction is completed; when the first monomer is lactide, the second monomer is glycolide; when the first monomer is glycolide, the second monomer is lactide. By adopting this system, regular polyglycolide and lactide block copolymers (i.e., PLGA copolymers) with specific molecular structures can be continuously synthesized, and the synthesized lactide / glycolide copolymers have the advantages of easy control of product molecular structure, stable product quality, high molecular weight, low molecular weight distribution, low monomer content, good thermal processing performance and thermal stability, etc.; the continuous synthesis of lactide / glycolide copolymers can be realized, which is more conducive to engineering scale-up, large-scale production, and solving the problem of insufficient supply of PLGA in the market.

[0005] The production system is used to prepare lactide / glycolide copolymers. Since lactide monomers include three configurations: Meso-lactide, L-lactide, and D-lactide, among which Meso-lactide is an impurity, L-lactide is usually used to prepare lactide / glycolide copolymers. However, the production system does not pretreat the lactide monomer to remove Meso-lactide, and the obtained lactide / glycolide copolymers have low purity and contain lactide / glycolide copolymer impurities synthesized from Meso-lactide. Utility Model Content

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a lactide / glycolide copolymer production system to remove Meso-lactide and thereby improve the purity of the obtained lactide / glycolide copolymer.

[0007] The utility model provides a lactide / glycolide copolymer production system, comprising: a mixing device, a prepolymerization reactor, a polymerization reactor and an end-capping devolatilizer which are sequentially connected along a reaction direction; the mixing device is provided with a feed inlet, the feed inlet of the mixing device is connected with a falling film crystallizer, and the falling film crystallizer is provided with a feed inlet and a cold and hot coal inlet.

[0008] The principle of the lactide / glycolide copolymer production system of the utility model is that by adding a falling film crystallizer connected to the feed inlet of the mixing device, Meso-lactide can be effectively removed, thereby improving the purity of the obtained lactide / glycolide copolymer.

[0009] Optionally, the mixing device includes a connected static mixer and a prepolymerization mixer, and the static mixer and the prepolymerization mixer are both provided with a feed port and a discharge port. The feed port of the static mixer is connected to the discharge port of the falling film crystallizer, the discharge port of the static mixer is connected to the discharge port of the prepolymerization mixer, and the discharge port of the prepolymerization mixer is connected to the prepolymerization reactor.

[0010] In the utility model, by configuring the mixing device to include a static mixer and a prepolymerization mixer which are connected, L-lactide and glycolide can be further fully mixed, and the material can be preheated by the prepolymerization mixer, thereby improving the yield.

[0011] Optionally, the prepolymerization mixer is a pipeline reactor or a dynamic mixer.

[0012] Optionally, the lactide / glycolide copolymer production system also includes a distillation tower, which is provided with a feed inlet and a discharge port, and an M-lactide storage container is arranged on a connecting pipe between the feed inlet of the distillation tower and the discharge port of the falling film crystallizer, and the discharge port of the distillation tower is connected to the feed inlet of the falling film crystallizer.

[0013] In the utility model, by adding a distillation tower, and connecting the feed port of the distillation tower to the discharge port of the falling film crystallizer, and connecting the discharge port of the distillation tower to the feed port of the falling film crystallizer, the mother liquor obtained after crystallization can be separated and purified by the distillation tower and then sent to the falling film crystallizer again, so as to recover the Meso-lactide in the mother liquor and obtain a high-purity Meso-lactide by-product.

[0014] Optionally, the gas outlet of the distillation tower is connected to the feed inlet of the falling film crystallizer.

[0015] In the utility model, by connecting the gas outlet of the distillation tower to the feed port of the falling film crystallizer, the Meso-lactide volatilized from the distillation tower can be sent to the falling film crystallizer for treatment, so as to improve the purity of the Meso-lactide and obtain a high-purity Meso-lactide by-product.

[0016] Optionally, the falling film crystallizer is provided with a material circulation inlet, and the lactide / glycolide copolymer production system further comprises a static crystallizer, which is located on a connecting pipe between the falling film crystallizer and the mixing device, and is provided with cold and hot coal inlets.

[0017] In the utility model, by adding a static crystallizer on the communicating pipeline between the falling film crystallizer and the mixing device, the crystallized product obtained by crystallization can be sent to the falling film crystallizer after static crystallization treatment, so as to reduce energy consumption.

[0018] Optionally, the lactide / glycolide copolymer production system also includes a cold coal storage container, a heat medium storage container and a heat pump system, the heat pump system is connected to the cold coal storage container and the heat medium storage container, the cold coal storage container and the heat medium storage container are both connected to the cold and hot coal inlets of the falling film crystallizer and / or the static crystallizer, and the heat medium storage container is also connected to the end-capped devolatilizer.

[0019] In the utility model, a cold coal storage container, a heat medium storage container and a heat pump system are added, and the heat pump system is connected to the cold coal storage container and the heat medium storage container, the cold coal storage container and the heat medium storage container are connected to the cold and hot coal inlets of the falling film crystallizer and / or the static crystallizer, and the heat medium storage container is also connected to the end-capped devolatilizer, so that the crystallization temperature, crystallization time, devolatilization temperature and devolatilization time can be accurately controlled, thereby further improving the purity of lactide and lactide / glycolide copolymer and reducing energy consumption.

[0020] Optionally, a gas outlet is provided at the top of the end-capped devolatilizer, a feed port is provided at the prepolymerization reactor, the gas outlet of the end-capped devolatilizer is connected to the feed port provided at the prepolymerization reactor, and a cooling device is provided on the connecting pipe between the end-capped devolatilizer and the feed port provided at the prepolymerization reactor.

[0021] In the utility model, by connecting the gas outlet of the end-capping devolatilizer to the feed port provided in the prepolymerization reactor, and arranging a cooling device on the connecting pipeline between the end-capping devolatilizer and the feed port provided in the prepolymerization reactor, the L-lactide discharged from the end-capping devolatilizer can be sent back to the prepolymerization reactor after cooling, thereby further improving the yield.

[0022] Optionally, the prepolymerization reactor is a microreactor.

[0023] In the utility model, by configuring the prepolymerization reactor to adopt a microreactor, L-lactide, glycolide, a catalyst and a polymerization regulator can be fully mixed, heat transferred and mass transferred, thereby improving the yield.

[0024] Optionally, the polymerization reactor is a plug flow reactor.

[0025] In the utility model, by configuring the polymerization reactor to adopt a plug flow reactor, the L-lactide monomer prepolymer (or glycolide monomer prepolymer), the glycolide monomer (or lactide monomer), the catalyst and the polymerization regulator can be continuously mixed, efficiently heat transferred and distributed in the plug flow reactor, thereby effectively improving the mass transfer efficiency and the heat transfer efficiency; the L-lactide monomer prepolymer (or glycolide monomer prepolymer), the glycolide monomer (or lactide monomer), the catalyst and the polymerization regulator flow in the plug flow reactor in a plug flow manner, so that the residence time of the L-lactide monomer prepolymer (or glycolide monomer prepolymer), the glycolide monomer (or lactide monomer), the catalyst and the polymerization regulator in the plug flow reactor is kept consistent, the whole reaction process is more stable, and a high yield and a high conversion rate of the reaction are achieved.

[0026] Optionally, the falling film crystallizer is provided with a material circulation inlet, and the material circulation inlet is connected to a discharge port of the falling film crystallizer via a circulation pipeline.

[0027] In the utility model, by adding a material circulation inlet and connecting the material circulation inlet of the falling film crystallizer to the discharge port of the falling film crystallizer, the obtained L-lactide crystal product can be crystallized multiple times, thereby further improving the purity of the L-lactide. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic structural diagram of the polylactic acid production system of Example 1;

[0029] Figure 2 It is a structural schematic diagram of the polylactic acid production system of Example 2;

[0030] Figure 3 It is a structural schematic diagram of the polylactic acid production system of Example 3;

[0031] Figure 4This is a schematic diagram of the structure of the polylactic acid production system of Example 4.

[0032] Reference numerals

[0033] 1- Falling film crystallizer;

[0034] 2-static mixer;

[0035] 3- prepolymerization mixer;

[0036] 4-prepolymerization reactor;

[0037] 5-polymerization reactor;

[0038] 6-end-capped devolatilizer;

[0039] 7-L-lactide storage container;

[0040] 8-Cooling device;

[0041] 9-distillation tower;

[0042] 10-M-lactide storage container;

[0043] 11-static crystallizer;

[0044] 12-Refrigerated coal storage container;

[0045] 13-heat medium storage container;

[0046] 14-Heat pump system. DETAILED DESCRIPTION

[0047] The following is an explanation of the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0048] It should be noted that the diagram provided in the present embodiment only illustrates the basic concept of the utility model in a schematic manner, so the diagram only shows the components related to the utility model rather than drawing according to the number, shape and size of the components during actual implementation. The type, quantity and ratio of each component during actual implementation can be changed at will, and the component layout type may also be more complicated. The structure, ratio, size, etc. illustrated in the drawings of the present specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that the utility model can implement, so they have no technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the utility model without affecting the effect that the utility model can produce and the purpose that can be achieved. At the same time, the terms such as "upper", "top", "bottom" etc. quoted in this specification are only for the convenience of narration, and are not used to limit the scope of the utility model. The change or adjustment of its relative relationship should also be regarded as the scope of the utility model that can be implemented without substantially changing the technical content.

[0049] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present disclosure.

[0050] The utility model provides a lactide / glycolide copolymer production system, comprising: a static mixer, a prepolymerization mixer, a prepolymerization reactor, a polymerization reactor and an end-capping devolatilizer which are sequentially connected along the reaction direction;

[0051] Both the static mixer and the prepolymerization mixer are provided with a feed inlet and a discharge outlet;

[0052] The feed inlet of the static mixer is connected to a falling film crystallizer, the falling film crystallizer is provided with a feed inlet, a discharge port and a material circulation inlet, and the discharge port of the falling film crystallizer is connected to the material circulation inlet of the falling film crystallizer through a circulation pipeline;

[0053] The discharge port of the static mixer is connected to the discharge port of the prepolymerization mixer, and the discharge port of the prepolymerization mixer is connected to the prepolymerization reactor; the prepolymerization mixer adopts a pipeline reactor or a dynamic mixer;

[0054] The prepolymerization reactor adopts a microreactor;

[0055] The polymerization reactor adopts a plug flow reactor;

[0056] A gas outlet is arranged on the upper part of the end-capping devolatilizer, a feed port is arranged on the prepolymerization reactor, the gas outlet of the end-capping devolatilizer is connected to the feed port arranged on the prepolymerization reactor, and a cooling device is arranged on the connecting pipeline between the end-capping devolatilizer and the feed port arranged on the prepolymerization reactor.

[0057] In another embodiment of the present invention, the lactide / glycolide copolymer production system further comprises a distillation tower, the distillation tower is provided with a feed inlet and a discharge port, and the discharge port of the distillation tower is connected to the feed inlet of the falling film crystallizer.

[0058] In another embodiment of the utility model, the lactide / glycolide copolymer production system also includes a static crystallizer, which is provided with a feed inlet, a discharge port and cold and hot coal inlets, and the static crystallizer is located on a connecting pipe between the falling film crystallizer and the static mixer.

[0059] In another embodiment of the utility model, the lactide / glycolide copolymer production system also includes a cold coal storage container, a heat medium storage container and a heat pump system, the heat pump system is connected to the cold coal storage container and the heat medium storage container, the cold coal storage container and the heat medium storage container are connected to the cold and hot coal inlets of the falling film crystallizer and / or the static crystallizer, and the heat medium storage container is also connected to the end-capped devolatilizer.

[0060] The present invention is described in detail below through specific examples. It should also be understood that the following examples are only used to specifically illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are only an example within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description of this article, and are not limited to the specific values ​​​​exemplified below. It should be noted that, unless otherwise specified, the "wt%" described in the present invention refers to the mass content.

[0061] Example 1

[0062] See also Figure 1 , Figure 1 Schematic diagram of the structure of the lactide / glycolide copolymer production system of this embodiment, which is used to produce lactide / glycolide copolymers.

[0063] like Figure 1 As shown, the lactide / glycolide copolymer production system of this embodiment includes: a falling film crystallizer 1, a static mixer 2, a prepolymerization mixer 3, a prepolymerization reactor 4, a polymerization reactor 5 and a capping devolatilizer 6 which are sequentially connected along the reaction direction.

[0064] Please continue reading Figure 1The falling film crystallizer 1 is used to separate and purify lactide to remove Meso-lactide (hereinafter referred to as M-lactide) and the like in lactide. The falling film crystallizer 1 is provided with a feed port (not shown), a discharge port (not shown), a material circulation inlet (not shown), a cold and hot coal inlet (not shown) and a cold and hot coal outlet (not shown). The discharge port of the falling film crystallizer 1 is connected to the material circulation inlet of the falling film crystallizer 1 through a circulation pipeline, and a centrifugal pump (not shown) and a switch valve (not shown) are provided on the circulation pipeline. The falling film crystallizer 1 can adopt a tubular falling film crystallizer or a plate falling film crystallizer. The tubular falling film crystallizer and the plate falling film crystallizer are prior arts and will not be described in detail here.

[0065] Specifically, in this embodiment, by connecting the discharge port of the falling film crystallizer 1 to the material circulation inlet of the falling film crystallizer 1 through a circulation pipeline, the obtained L-lactide crystal product can be crystallized multiple times to further improve the purity of the L-lactide.

[0066] Please continue reading Figure 1 The static mixer 2 is used as a place for mixing L-lactide, glycolide, a catalyst (such as stannous octoate) and a polymerization regulator (such as tert-butyldimethylsilanol). The static mixer 2 is provided with a first feed port (not shown), a second feed port and a discharge port (not shown). The first feed port of the static mixer 2 is connected to the discharge port of the falling film crystallizer 1. A switch valve (not shown) and a centrifugal pump (not shown) are provided on the connecting pipe between the first feed port of the static mixer 2 and the discharge port of the falling film crystallizer 1. The static mixer is a prior art and will not be described in detail here.

[0067] Please continue reading Figure 1 An L-lactide storage container 7 is provided on the connecting pipe between the falling film crystallizer 1 and the static mixer 2. The L-lactide storage container 7 is used as a storage container for L-lactide. A switch valve (not shown) and a centrifugal pump (not shown) are provided on the connecting pipe between the falling film crystallizer 1 and the L-lactide storage container 7 and the connecting pipe between the L-lactide storage container 7 and the static mixer 2.

[0068] Please continue reading Figure 1The prepolymer mixer 3 is used as a place for further mixing and preheating L-lactide and glycolide in the presence of a catalyst (such as stannous octoate) and a polymerization regulator (such as tert-butyldimethylsilanol). The prepolymer mixer 3 is provided with a feed port (not shown) and a discharge port (not shown). The feed port of the prepolymer mixer 3 is connected to the discharge port of the static mixer 2. A switch valve (not shown) and a centrifugal pump (not shown) are provided on the connecting pipe between the feed port of the prepolymer mixer 3 and the discharge port of the static mixer 2. The prepolymer mixer 3 adopts a pipeline reactor (shown as pipeline reactor 603 in structure CN216172365U) or a dynamic mixer. The pipeline reactor and the dynamic mixer are prior art and will not be described in detail here.

[0069] Specifically, in this embodiment, by providing the static mixer 2 and the prepolymerization mixer 3 which are connected to each other, L-lactide and glycolide can be further fully mixed, thereby improving the yield.

[0070] The principle of the lactide / glycolide copolymer production system of this embodiment is: by adding a falling film crystallizer 1 connected to the feed port of the static mixer 22, M-lactide can be effectively removed, thereby improving the purity of the obtained lactide / glycolide copolymer.

[0071] Please continue reading Figure 1 The prepolymerization reactor 4 is used as a place for L-lactide monomer or glycolide monomer to form monomer prepolymer through ring-opening polymerization through prepolymerization reaction. The prepolymerization reactor 4 is provided with a feed port (not shown) and a discharge port (not shown). The feed port of the prepolymerization reactor 4 is connected to the discharge port of the prepolymerization mixer 3. A switch valve (not shown) and a centrifugal pump (not shown) are provided on the connecting pipe between the feed port of the prepolymerization reactor 4 and the discharge port of the prepolymerization mixer 3. The prepolymerization reactor 4 adopts a microreactor, which is a prior art and will not be described in detail here.

[0072] Specifically, in this embodiment, by configuring the prepolymerization reactor 4 to adopt a microreactor, L-lactide, glycolide, a catalyst (such as stannous octoate) and a polymerization regulator (such as tert-butyldimethylsilanol) can be fully mixed, heat-transferred and mass-transferred, thereby improving the yield.

[0073] Please continue to refer to 1. The polymerization reactor 5 is used as a reaction place for L-lactide monomer prepolymer and glycolide monomer to form L-lactide-glycolide copolymer by ring-opening polymerization or glycolide monomer prepolymer and L-lactide monomer to form lactide-glycolide copolymer by ring-opening polymerization. The polymerization reactor 5 is provided with a feed port (not shown) and a discharge port (not shown). The feed port of the polymerization reactor 5 is connected to the discharge port of the prepolymerization reactor 4. The connecting pipeline between the feed port of the polymerization reactor 5 and the discharge port of the prepolymerization reactor 4 is provided with a switch valve (not shown) and a centrifugal pump (not shown). The polymerization reactor 5 can adopt a plug flow reactor (shown as the pipeline reactor 700 in the structure CN216172365U). The plug flow reactor is a prior art and will not be described here.

[0074] Specifically, in this embodiment, by configuring the polymerization reactor 5 to adopt a plug flow reactor, the L-lactide monomer prepolymer (or glycolide monomer prepolymer), glycolide monomer (or lactide monomer), catalyst and polymerization regulator can be continuously mixed, efficiently heat transferred and distributed in the plug flow reactor, thereby effectively improving the mass transfer efficiency and heat transfer efficiency; the L-lactide monomer prepolymer (or glycolide monomer prepolymer), glycolide monomer (or lactide monomer), catalyst and polymerization regulator flow in the plug flow reactor in a plug flow manner, so that the residence time of the L-lactide monomer prepolymer (or glycolide monomer prepolymer), glycolide monomer (or lactide monomer) and polymerization regulator in the plug flow reactor is kept consistent, the entire reaction process is more stable, and a high yield and a high conversion rate of the reaction are achieved.

[0075] Please continue to refer to 1. The end-capping devolatilizer 6 is used as a place for end-capping devolatilization reaction of the lactide / glycolide copolymer after the polymerization reaction is completed. The end-capping devolatilizer 6 is provided with a first feed port (not shown), a second feed port (not shown) and a discharge port (not shown), and a gas outlet (not shown) is provided on the upper part of the end-capping devolatilizer 6. The first feed port of the end-capping devolatilizer 6 is connected to the discharge port of the polymerization reactor 5, and the gas outlet of the end-capping devolatilizer 6 is connected to the feed port of the prepolymerization reactor 4. A cooling device 8 is provided on the connecting pipe between the end-capping devolatilizer 6 and the feed port of the prepolymerization reactor 4. A switch valve (not shown) and a centrifugal pump (not shown) are provided on the connecting pipe between the feed port of the end-capping devolatilizer 6 and the discharge port of the first polymerization reactor 5 and the connecting pipe between the cooling device 8 and the feed port of the prepolymerization reactor 4. The end-capping devolatilizer 6 may be a DSXL end-capping devolatilizer, and the cooling device 8 may be a cold trap or a condenser. The DSXL end-capping devolatilizer, cold trap and condenser are prior arts and will not be described in detail here.

[0076] Specifically, in this embodiment, by connecting the gas outlet of the end-capping devolatilizer 6 to the feed inlet of the prepolymerization reactor 4, and providing a cooling device 7 on the connecting pipe between the end-capping devolatilizer 6 and the feed inlet of the prepolymerization reactor 4, the L-lactide discharged from the end-capping devolatilizer can be cooled and then sent back to the prepolymerization reactor 4, thereby further improving the yield.

[0077] Please continue reading Figure 1 The lactide / glycolide copolymer production system of this embodiment further includes a distillation tower 9, which is provided with a feed inlet (not shown), a discharge port (not shown) and an air outlet, and the air outlet is located at the top of the distillation tower 9. The feed inlet of the distillation tower 9 is connected to the discharge port of the falling film crystallizer 1, and the discharge port of the distillation tower 9 is connected to the feed inlet of the falling film crystallizer 1. The M-lactide storage container 10 is provided on the connecting pipe between the feed inlet of the distillation tower 9 and the discharge port of the falling film crystallizer 1. The air outlet of the distillation tower 9 is connected to the feed inlet of the falling film crystallizer 1. The connecting pipe between the feed inlet of the distillation tower 9 and the discharge port of the M-lactide storage container 10 and the connecting pipe between the M-lactide storage container 10 and the discharge port of the falling film crystallizer 1 are both provided with a switch valve (not shown) and a centrifugal pump (not shown).

[0078] Specifically, in this embodiment, by adding a distillation tower 9 and connecting the feed port of the distillation tower 9 to the discharge port of the falling film crystallizer 1, and connecting the discharge port of the distillation tower 9 to the feed port of the falling film crystallizer 1, the mother liquor obtained after crystallization can be separated and purified by the distillation tower 9 and then sent to the falling film crystallizer 1 again, so as to recover the Meso-lactide in the mother liquor to obtain a high-purity Meso-lactide by-product; by connecting the gas outlet of the distillation tower 9 to the feed port of the falling film crystallizer 1, the Meso-lactide volatilized from the distillation tower 8 can be sent to the falling film crystallizer 1 for treatment, so as to improve the purity of the Meso-lactide and obtain a high-purity Meso-lactide by-product.

[0079] The production process of the lactide / glycolide copolymer production system of this embodiment is as follows:

[0080] The lactide material (the flow rate is 2000 kg / h, and the material contains about 92 wt% of L-lactide and about 8 wt% of Meso-lactide) which has been dehydrated, free acid and other light components removed, and oligomers and other heavy components removed, is fed into a falling film crystallizer 1, and the temperature of the falling film crystallizer 1 is adjusted to 40-140° C., and a mother solution A having a purity of 99.9 wt% and a Meso-lactide concentration of about 60 wt% is obtained through three-stage crystallization;

[0081] The switch valve and the centrifugal pump on the connecting pipe between the discharge port of the falling film crystallizer 1 and the feed port of the distillation tower 9 are opened, and the mother liquor A is pumped into the distillation tower 9. The top temperature of the distillation tower 9 is adjusted to 145-150° C., the bottom temperature is adjusted to 215-220° C., and the top pressure is adjusted to 2 kPa. A material B having a Meso-lactide concentration of about 95 wt% is obtained at the top of the tower, and a material C having a Meso-lactide concentration of about 6 wt% is obtained at the bottom of the tower. The switch valve on the connecting pipe between the discharge port of the distillation tower 9 and the feed port of the falling film crystallizer 1 is opened, and the material C is sent to the falling film crystallizer 1, mixed with the material after dehydration, removal of light components such as free acid, and removal of heavy components such as oligomers, and then tertiary crystallization is performed again to obtain Meso-lactide with a purity of about 99.8 wt% and a mother liquor D with a Meso-lactide concentration of about 75 wt%;

[0082] The switch valve on the connecting pipe between the discharge port of the distillation tower 9 and the feed port of the falling film crystallizer 1 is closed, and the switch valve and the centrifugal pump on the connecting pipe between the feed port of the falling film crystallizer 1 and the gas outlet of the distillation tower 9 are opened. Material B is sent to the falling film crystallizer and mixed with the material after dehydration, removal of light components such as free acid and removal of heavy components such as oligomers, and then tertiary crystallization is performed again to obtain Meso-lactide with a purity of about 99.8wt%;

[0083] The switch valve and the centrifugal pump on the connecting pipe between the discharge port of the falling film crystallizer 1 and the M-lactide storage container 10 are opened, and Meso-lactide with a purity of about 99.8 wt% is delivered to the M-lactide storage container 10;

[0084] The switch valve and the centrifugal pump on the connecting pipe between the discharge port of the falling film crystallizer 1 and the L-lactide storage container 7 are closed, and the L-lactide with a content of 99.9% is sent to the L-lactide storage container 7. The switch valve and the centrifugal pump on the connecting pipe between the L-lactide storage container 7 and the static mixer 2 are opened, and the L-lactide with a content of 99.9% is sent to the static mixer 2. Glycolide with a temperature of 145° C. and a content of about 99.9wt% (flow rate of 200kg / h), stannous octoate (2.4kg / h) and a polymerization regulator (4kg / h, specifically tert-butyldimethylsilanol) are added to the static mixer 2 through the second feed port, and the L-lactide, glycolide, stannous octoate and the polymerization regulator are mixed in the static mixer 2 to obtain a first mixed material;

[0085] The switch valve and the centrifugal pump on the connecting pipe between the static mixer 2 and the prepolymerization mixer 3 are opened, and the first mixed material is sent to the prepolymerization mixer 3, and the L-lactide, glycolide, stannous octoate and the polymerization regulator are further mixed in the prepolymerization mixer 3 and preheated to obtain the second mixed material;

[0086] The switch valve and the centrifugal pump on the connecting pipe between the prepolymerization mixer 3 and the prepolymerization reactor 4 are opened, and the second mixed material is sent into the prepolymerization reactor 4. The pressure of the prepolymerization reactor 4 is adjusted to 5-7 MPa and the temperature is adjusted to 180-220° C. L-lactide and glycolide undergo polymerization reaction under the catalytic action of stannous octoate catalyst to obtain a material containing lactide / glycolide copolymer. The polymerization regulator adjusts the molecular weight of the lactide / glycolide copolymer, thereby achieving controllability and adjustability of the molecular weight of the lactide / glycolide copolymer;

[0087] The switch valve and the centrifugal pump on the connecting pipe between the prepolymerization reactor 4 and the polymerization reactor 5 are opened, and the material containing the lactide / glycolide copolymer is sent to the polymerization reactor 5. The pressure of the polymerization reactor 5 is adjusted to 5-7 MPa and the temperature is adjusted to 180-220° C. The unreacted L-lactide and glycolide continue to react in the polymerization reactor 5 to obtain a reaction product;

[0088] The switch valve and the centrifugal pump on the connecting pipe between the polymerization reactor 5 and the end-capping devolatilizer 6 are opened, and the reaction product is fed into the end-capping devolatilizer 6. An end-capping agent (such as at least one of a phosphorus compound, an antioxidant, an acrylic acid derivative and an organic peroxide, and the amount of the end-capping agent is 1.5 wt% of the mass of the crude lactide / glycolide copolymer) is added to the end-capping devolatilizer 6 through the second feed port. In the end-capping devolatilizer 6, the lactide / glycolide copolymer undergoes an end-capping reaction under the action of the end-capping agent. In this process, L-lactide in the crude lactide / glycolide copolymer is separated out;

[0089] The switch valve and the centrifugal pump on the connecting pipe between the gas outlet of the end-capping volatilizer 6 and the prepolymerization reactor 4 are opened, and the L-lactide is sent to the prepolymerization reactor 4 after being cooled to recover the L-lactide and improve the yield.

[0090] Example 2

[0091] like Figure 2 The lactide / glycolide copolymer production system shown in this embodiment is different from embodiment 1 in that the distillation device 9 is not included, and the discharge port of the falling film crystallizer 1 is connected to the M-lactide storage container 10.

[0092] Example 3

[0093] like Figure 3 The lactide / glycolide copolymer production system shown in this embodiment is different from embodiment 1 in that it also includes a static crystallizer 11.

[0094] Please continue reading Figure 3The static crystallizer 11 is located on the connecting pipe between the falling film crystallizer 1 and the L-lactide storage container 7. The static crystallizer 11 is provided with a feed port (not shown), a discharge port (not shown), a cold and hot coal inlet (not shown) and a cold and hot coal outlet (not shown). The feed port of the static crystallizer 11 is connected to the discharge port of the falling film crystallizer 1, and the discharge port of the static crystallizer 11 is connected to the L-lactide storage container 7.

[0095] Specifically, by adding a static crystallizer 11 to the connecting pipe between the falling film crystallizer 1 and the L-lactide storage container 7, it is possible to avoid using the falling film crystallizer 1 for multi-stage crystallization, thereby reducing energy consumption.

[0096] Example 4

[0097] like Figure 4 The lactide / glycolide copolymer production system shown in this embodiment is different from the embodiment 3 in that it also includes a cold coal storage container 12 , a heat medium storage container 13 and a heat pump system 14 .

[0098] Please continue reading Figure 4 The heat pump system 14 is connected to the hot coal storage container 13 and the refrigerant storage container 12. The heat pump system is a prior art and will not be described in detail here.

[0099] Please continue reading Figure 4 The end-capped devolatilizer 6 is provided with a heat medium inlet, and the cold coal storage container 12 and the heat medium storage container 13 are used as storage containers for the cold medium and the heat medium, respectively. The cold coal storage container 12 and the heat medium storage container 13 are both connected to the cold and hot coal inlets of the falling film crystallizer 1 and / or the static crystallizer 11, and the heat medium storage container 13 is also connected to the heat medium inlet of the end-capped devolatilizer 6.

[0100] Specifically, in this embodiment, by adding a hot coal storage container 13, a refrigerant storage container 12 and a heat pump system 14, and connecting the hot coal storage container 13 and the refrigerant storage container 11 to the hot and cold coal inlets of the falling film crystallizer 1 and / or the static crystallizer 6, and the hot medium storage container 13 is also connected to the hot medium inlet of the end-capped devolatilizer 6, the crystallization temperature, crystallization time, devolatilization temperature and devolatilization time can be accurately controlled, thereby improving the purity of L-lactide and the purity of the lactide / glycolide copolymer and reducing energy consumption.

[0101] Without limitation thereto, in the present application, the M-lactide storage container 10 may be connected to the static mixer 2, thereby using M-lactide and glycolide as raw materials to produce a lactide / glycolide copolymer production system for use as raw materials for softer materials such as shopping bags.

[0102] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by a person with ordinary knowledge in the relevant technical field without departing from the spirit and technical ideas disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. A lactide / glycolide copolymer production system, characterized in that: include: A mixing device, a prepolymerization reactor, a polymerization reactor and a capped devolatilizer are sequentially connected along the reaction direction. The mixing device is provided with a feed port, and the feed port of the mixing device is connected with a falling film crystallizer. The falling film crystallizer is provided with a feed port, a discharge port and cold and hot coal inlets.

2. The lactide / glycolide copolymer production system according to claim 1, characterized in that: The mixing device comprises a static mixer and a prepolymerization mixer, both of which are provided with a feed port and a discharge port, the feed port of the static mixer is connected to the discharge port of the falling film crystallizer, the discharge port of the static mixer is connected to the discharge port of the prepolymerization mixer, and the discharge port of the prepolymerization mixer is connected to the prepolymerization reactor.

3. The lactide / glycolide copolymer production system according to claim 2, characterized in that: The prepolymerization mixer is a pipeline reactor or a dynamic mixer.

4. The lactide / glycolide copolymer production system according to claim 1, characterized in that: It also includes a distillation tower, which is provided with a feed inlet, a discharge port and an air outlet. The feed inlet of the distillation tower is connected to the discharge port of the falling film crystallizer, and the discharge port of the distillation tower is connected to the feed inlet of the falling film crystallizer.

5. The lactide / glycolide copolymer production system according to claim 4, characterized in that: The gas outlet of the distillation tower is connected to the feed inlet of the falling film crystallizer.

6. The lactide / glycolide copolymer production system according to claim 1, characterized in that: The falling film crystallizer is provided with a material circulation inlet, and the lactide / glycolide copolymer production system also includes a static crystallizer, which is located on the connecting pipeline between the falling film crystallizer and the mixing device, and the static crystallizer is provided with cold and hot coal inlets.

7. The lactide / glycolide copolymer production system according to claim 6, characterized in that: It also includes a cold coal storage container, a heat medium storage container and a heat pump system, the heat pump system is connected to the cold coal storage container and the heat medium storage container, the cold coal storage container and the heat medium storage container are all connected to the cold and hot coal inlets of the falling film crystallizer and / or the static crystallizer, and the heat medium storage container is also connected to the capped devolatilizer.

8. The lactide / glycolide copolymer production system according to claim 1, characterized in that: A gas outlet is provided at the top of the end-capped devolatilizer, a feed port is provided at the prepolymerization reactor, the gas outlet of the end-capped devolatilizer is connected to the feed port provided at the prepolymerization reactor, and a cooling device is provided on the connecting pipeline between the end-capped devolatilizer and the feed port provided at the prepolymerization reactor.

9. The lactide / glycolide copolymer production system according to claim 1, characterized in that: The prepolymerization reactor is a microreactor.

10. The lactide / glycolide copolymer production system according to claim 1, characterized in that: The polymerization reactor adopts a plug flow reactor; And / or, the falling film crystallizer is provided with a material circulation inlet, and the material circulation inlet is connected to the discharge port of the falling film crystallizer through a circulation pipeline.

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