CN219400134U

CN219400134U - Process system for preparing polyglycolic acid from glycolide

Info

Publication number: CN219400134U
Application number: CN202320286000.7U
Authority: CN
Inventors: 杨秀秀; 修轶鲲; 刘征; 汪婧妍; 郭玉飞; 周宽; 钱俊; 喻军
Original assignee: High Chemical Shaanxi Management Co ltd; East China Engineering Science and Technology Co Ltd
Current assignee: High Chemical Shaanxi Management Co ltd; East China Engineering Science and Technology Co Ltd
Priority date: 2023-02-22
Filing date: 2023-02-22
Publication date: 2023-07-25
Anticipated expiration: 2033-02-22

Abstract

The utility model relates to the technical field of polyglycolic acid preparation, in particular to a process system for preparing polyglycolic acid from glycolide, which comprises a prepolymerization kettle, a dynamic mixer, a double-screw extruder, a granulator and a material tank which are sequentially communicated through pipelines, wherein a stirring paddle is arranged in the prepolymerization kettle; secondly, in the mixing step, the polyglycolic acid and glycolide monomer molecules obtained by pre-polymerization are mixed and reacted in a dynamic mixer, and the addition of the glycolide monomer increases the reaction collision probability of the system, reduces the residual quantity of the monomer in the reaction system, improves the monomer conversion rate and reduces the molecular weight distribution; therefore, the polyglycolic acid prepared by the process system of the utility model has the weight average molecular weight of more than 20 ten thousand and the molecular weight distribution of less than 1.5.

Description

Process system for preparing polyglycolic acid from glycolide

Technical Field

The utility model relates to the technical field of polyglycolic acid preparation, in particular to a process system for preparing polyglycolic acid from glycolide.

Background

Polyglycolic acid (PGA), also known as polyglycolide or polyglycolic acid, is a biodegradable aliphatic polyester material with the simplest chemical structure, and can finally form carbon dioxide and water under the action of enzymolysis and dissolution in microorganisms or organisms. Polyglycolic acid has excellent biocompatibility, so that the polyglycolic acid can be used for preparing surgical sutures, stents, orthopedic materials and the like. Meanwhile, the polyglycolic acid gas barrier property is outstanding, the barrier property to oxygen and water vapor is 1000 times that of polylactic acid, and the barrier property is not influenced by relative humidity. Compared with PLA and PBAT, the polyglycolic acid has good heat resistance, and can greatly improve the heat resistance of the product.

At present, polyglycolic acid is obtained by a one-step method, namely a glycolic acid polycondensation method through direct esterification polymerization of glycolic acid, and the method has the advantages of simple steps and low cost, but the direct polycondensation reaction condition is harsh, the later dehydration is difficult, and the molecular weight of the obtained product is generally not high, and is usually less than 2 ten thousand; the other method is a two-step method, namely a glycolide ring-opening polymerization method, wherein an oligomer is obtained through glycolic acid polycondensation, then the oligomer is thermally decomposed to obtain cyclic glycolide, and finally the glycolide ring-opening polymerization is carried out to obtain polyglycolic acid. The method has the advantages of mild reaction conditions, high purity and capability of obtaining polyglycolic acid with molecular weight of more than 10 ten thousand, although the process is complex compared with a one-step method.

The prior two-step method generally obtains polyglycolic acid by directly polymerizing the obtained high-purity glycolide monomer, however, the viscosity of the polyglycolic acid is high in the later reaction period, so that reactants in the later reaction period with high molecular weight are difficult to fully mix in the prior reaction system, the molecular weight molecules are relatively wide, the subsequent processing of molding materials is not facilitated, and equipment is easy to damage.

Disclosure of Invention

The utility model aims to solve the problems in the prior art and provide a process system for preparing polyglycolic acid from glycolide, which can prepare polyglycolic acid by adopting different equipment through a system of three steps of prepolymerization, mixing and final polymerization according to the characteristics of different viscosities in different polymerization stages,

the specific technical scheme is as follows: a process system for preparing polyglycolic acid from glycolide comprises a prepolymerization kettle 1, a dynamic mixer 3, a double screw extruder 5, a granulator 7 and a material tank 8 which are sequentially communicated through pipelines,

the inside of the pre-polymerization kettle 1 is provided with a stirring paddle, the top of the pre-polymerization kettle 1 is communicated with a glycolide inlet, a catalyst inlet, a chain extender inlet and a nitrogen inlet through pipelines, the top of the pre-polymerization kettle 1 is communicated with the inlet of a first vacuum pump 2 through pipelines,

the top of the dynamic mixer 3 is communicated with a nitrogen inlet and a glycolide inlet through pipelines, the bottom of the dynamic mixer 3 is communicated with the inlet of a second vacuum pump 4 through pipelines,

the top of the double-screw extruder 5 is communicated with a nitrogen inlet through a pipeline, and the bottom of the double-screw extruder 5 is communicated with the inlet of the third vacuum pump 6 through a pipeline.

Further, the bottom outlet of the prepolymerization reactor 1 is communicated with the inlet of the dynamic mixer 3 through a pipeline, the outlet of the dynamic mixer 3 is communicated with the inlet of one end of the double-screw extruder 5 through a pipeline, the outlet of the other end of the double-screw extruder 5 is communicated with the inlet of the granulator 7 through a pipeline, and the outlet of the granulator 7 is communicated with the inlet of the material tank 8 through a pipeline.

Further, the stirring speed of the stirring paddle of the prepolymerization reactor 1 is 100-200 rpm, and the distance between the lower end of the stirring paddle and the bottom of the reactor is 2-7 mm.

Further, the set rotational speed of the dynamic mixer 3 is 50-200 rpm.

Further, the length-diameter ratio of the double-screw extruder 5 is 1:40-1:60, and the extrusion rotating speed is 30-90 r/min.

The beneficial technical effects of the utility model are as follows:

according to the process system for preparing polyglycolic acid from glycolide, provided by the utility model, a prepolymerization kettle, a dynamic mixer, a double-screw extruder, a granulator and a material tank are arranged according to the characteristics of different viscosities at different reaction stages, so that the steps of prepolymerization, mixing and final polymerization are realized, wherein the prepolymerization adopts the polymerization kettle, the mixing adopts the dynamic mixer, the final polymerization adopts the double-screw extruder, and reactants of the system at different stages can be fully mixed; secondly, in the mixing step, the polyglycolic acid and glycolide monomer molecules obtained by pre-polymerization are mixed and reacted in a dynamic mixer, and the addition of the glycolide monomer increases the reaction collision probability of the system, reduces the residual quantity of the monomer in the reaction system, improves the monomer conversion rate and reduces the molecular weight distribution; therefore, the polyglycolic acid prepared by the process system of the utility model has the weight average molecular weight of more than 20 ten thousand and the molecular weight distribution of less than 1.5.

Drawings

FIG. 1 is a system diagram of a process system for preparing polyglycolic acid from glycolide in accordance with the present utility model.

Wherein: 1-a prepolymerization reactor; 2-a first vacuum pump; 3-dynamic mixer; 4-a second vacuum pump; a 5-twin screw extruder; 6-a third vacuum pump; 7-granulating machine; 8-a material tank.

Detailed Description

The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent. It should be understood that the detailed description is presented by way of example only and is not intended to limit the utility model.

Example 1

Referring to fig. 1, a process system for preparing polyglycolic acid from glycolide comprises a prepolymerization reactor 1, a dynamic mixer 3, a double screw extruder 5, a granulator 7 and a material tank 8 which are sequentially communicated through pipelines,

Further, the set rotational speed of the dynamic mixer 3 is 50-200 rpm.

Example 2

A process system for preparing polyglycolic acid from glycolide of example 1 specifically comprises the following operative steps:

step 1): a pre-polymerization step, wherein in the pre-polymerization step,

adding glycolide into a prepolymerization reactor 1, wherein the mass fraction of the catalyst stannous octoate is 0.1-2 wt% of the glycolide, the mass fraction of the chain extender 1, 4-butanediol is 0.01-1 wt% of the glycolide, and introducing nitrogen into the prepolymerization reactor 1, wherein the flow rate is set to be 100-200 mL/min; raising the temperature to 170-230 ℃ at a temperature raising speed of 1-5 ℃ for minutes, and reacting for 0.5-2 hours under normal pressure;

the stirring speed of the stirring paddle of the prepolymerization reactor 1 is 100-200 rpm, the distance between the lower end of the stirring paddle and the bottom of the reactor is 2-7 mm, and the first vacuum pump 2 is used for replacing air in the prepolymerization reactor 1.

Step 2): a mixing step, in which the mixture is mixed,

injecting the oligomer obtained in the prepolymerization step into a dynamic mixer 3, simultaneously adding glycolide with the mass fraction of glycolide being 5-30 wt% in the prepolymerization step, introducing nitrogen into the dynamic mixer 3, setting the flow rate to be 100-200 mL/min, mixing at 170-230 ℃ and the rotation speed to be 50-200 rpm, inputting the obtained material into a double-screw extruder 5, and using a second vacuum pump 4 for replacing air in the dynamic mixer 3.

Step 3): a final step of the polymerization of the polymer,

the length-diameter ratio of the double-screw extruder 5 is 1:40-1:60, the third vacuum pump 6 is used for vacuumizing until the absolute pressure is less than 2 kPa, the temperature of each section of the double-screw extruder 5 is 200-230 ℃, the extrusion speed is 30-90 r/min, polyglycolic acid is obtained through reactive extrusion, then the polyglycolic acid is input into the granulator 7 for granulating, and finally the granules are conveyed to the material tank 8; the obtained polyglycolic acid had a weight-average molecular weight of 21 ten thousand and a molecular weight distribution of 1.45.

Specific: adding stannous octoate 2 g, 1.1 g of 1, 4-butanediol and 1 kg glycolide with purity more than 99.9% into a prepolymerization reactor 1, setting the stirring rotation speed to 170 rpm, setting the lower end of a stirring paddle to be 5mm away from the bottom of the reactor, introducing nitrogen at the flow rate of 150 mL/min, replacing air in the prepolymerization reactor with nitrogen through a first vacuum pump 2, then raising the temperature to 220 ℃ at the temperature raising speed of 1 ℃ for 1 hour, and reacting for 1 hour under normal pressure at 220 ℃. The oligomer obtained in the prepolymerization step was then fed into a dynamic mixer 3, while adding 0.1 g kg of glycolide, introducing nitrogen, setting the flow rate at 150 mL/min, displacing the air in the dynamic mixer 3 by a second vacuum pump 4, and then mixing at 225℃and 100 rpm, the resulting mass being fed into a twin screw extruder 5. The length-diameter ratio of the double-screw extruder 5 is 1:60, the third vacuum pump 6 is used for vacuumizing until the absolute pressure is less than 2 kPa, the temperature of each section of the double-screw extruder is 230 ℃, the extrusion speed is 60r/min, the polyglycolic acid is obtained through reaction extrusion, then the polyglycolic acid is input into the granulator 7 for granulating, and finally the polyglycolic acid is conveyed to the material tank 8.

It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the utility model and is not intended to limit the utility model, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the utility model are intended to be included within the scope of the utility model.

Claims

1. A process system for preparing polyglycolic acid from glycolide, characterized by: comprises a prepolymerization kettle (1), a dynamic mixer (3), a double screw extruder (5), a granulator (7) and a material tank (8) which are sequentially communicated through pipelines;

the inside of the pre-polymerization kettle (1) is provided with a stirring paddle, the top of the pre-polymerization kettle (1) is communicated with a glycolide inlet, a catalyst inlet, a chain extender inlet and a nitrogen inlet through pipelines, the top of the pre-polymerization kettle (1) is communicated with the inlet of a first vacuum pump (2) through pipelines,

the top of the dynamic mixer (3) is communicated with a nitrogen inlet and a glycolide inlet through a pipeline, and the bottom of the dynamic mixer (3) is communicated with the inlet of the second vacuum pump (4) through a pipeline;

the top of the double-screw extruder (5) is communicated with a nitrogen inlet through a pipeline, and the bottom of the double-screw extruder (5) is communicated with the inlet of the third vacuum pump (6) through a pipeline.

2. A process system for preparing polyglycolic acid from glycolide as defined in claim 1, wherein: the bottom outlet of the prepolymerization kettle (1) is communicated with the inlet of the dynamic mixer (3) through a pipeline, the outlet of the dynamic mixer (3) is communicated with the inlet of one end of the double-screw extruder (5) through a pipeline, the outlet of the other end of the double-screw extruder (5) is communicated with the inlet of the granulator (7) through a pipeline, and the outlet of the granulator (7) is communicated with the inlet of the material tank (8) through a pipeline.

3. A process system for preparing polyglycolic acid from glycolide as defined in claim 1, wherein: the stirring speed of the stirring paddle of the prepolymerization reactor (1) is 100-200 rpm, and the distance between the lower end of the stirring paddle and the bottom of the reactor is 2-7 mm.

4. A process system for preparing polyglycolic acid from glycolide as defined in claim 1, wherein: the setting rotation speed of the dynamic mixer (3) is 50-200 rpm.

5. A process system for preparing polyglycolic acid from glycolide as defined in claim 1, wherein: the length-diameter ratio of the double-screw extruder (5) is 1:40-1:60, and the extrusion rotating speed is 30-90 r/min.