CN113045742A - Preparation method of polyglycolic acid - Google Patents
Preparation method of polyglycolic acid Download PDFInfo
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- CN113045742A CN113045742A CN202110265693.7A CN202110265693A CN113045742A CN 113045742 A CN113045742 A CN 113045742A CN 202110265693 A CN202110265693 A CN 202110265693A CN 113045742 A CN113045742 A CN 113045742A
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- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
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- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
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Abstract
The invention discloses a preparation method of polyglycolic acid, which comprises the following steps: (1) reacting glycolic acid monomer and/or glycolate monomer with molecular weight Mw'polyglycolic acid of' is mixed and reacted to give a molecular weight Mw1The material (2); (2) molecular weight is Mw1Polymerizing the materials to obtain polyglycolic acid; the M isw' is a number of 1 ten thousand or more.
Description
Technical Field
The invention relates to the field of polymer preparation, in particular to a preparation method of polyglycolic acid.
Background
Polyglycolic acid (also called polyglycolic acid (abbreviated as PGA)) is a biodegradable aliphatic polymer, which can be hydrolyzed under the catalysis of enzymes or acids and bases in microorganisms or organisms to finally form carbon dioxide and water, and is a degradable material with great development potential.
At present, there are two main processes for preparing polyglycolic acid, one is to prepare polyglycolic acid by direct esterification and polycondensation of glycolic acid or glycolic acid ester substances (such as methyl glycolate), also known as a one-step process, and the other is to prepare polyglycolic acid by polycondensation of glycolic acid or glycolic acid ester substances (such as methyl glycolate) to prepare a polymer with low molecular weight, then heating and cracking the polymer with low molecular weight into a ring to form glycolide, and then performing ring-opening polymerization of glycolide, also known as a two-step process.
The one-step process has the following technical problems: 1) when glycolic acid is used for esterification and polycondensation, a commercially available catalyst is used, the reaction speed of glycolic acid is slow, and the reaction flow takes a long time (for example, more than 40 hours in general); 2) if glycolic acid ester substances (such as methyl glycolate) are used for esterification polycondensation, 10-30% or more of monomers are removed from the system without participating in the esterification reversible reaction, so that the monomer conversion rate is low, and the final reaction yield is far lower than the theoretical yield; 3) the molecular weight of the polyglycolic acid obtained is not so high (usually, the molecular weight is less than 2 ten thousand, or even less than 1 ten thousand) that the melt strength is insufficient at the time of molding processing, and it is difficult to use it for processing molding materials.
Therefore, there is a strong need in the art to provide a process for producing polyglycolic acid which is efficient and safe, can effectively increase the product yield, and can effectively shorten the reaction period.
Disclosure of Invention
The invention aims to provide a one-step method for preparing polyglycolic acid, which can overcome the existing defects in the field.
The invention provides a preparation method of polyglycolic acid, which comprises the following steps:
(1) reacting glycolic acid monomer and/or glycolate monomer with molecular weight Mw'polyglycolic acid of' is mixed and reacted to give a molecular weight Mw1The material (2); and
(2) molecular weight is Mw1Polymerizing the materials to obtain polyglycolic acid;
the M isw' is a number of 1 ten thousand or more.
In another embodiment, said Mw' is a number of 1 to 10 ten thousand.
In another embodiment, said Mw' is a number of 1 to 5 ten thousand.
In another embodiment, the molecular weight is M based on the mass of the glycolic acid monomer and/or glycolate monomer described in step (1)w' the amount of polyglycolic acid is 5-50%; preferably 10-20%.
In another embodiment, said Mw1Is 400- & gt 1000.
In another embodiment, the molecular weight in step (1) is Mw' of polyGlycolic acid is derived from the polyglycolic acid obtained in step (2).
In another embodiment, the reaction of step (1) is carried out at 180-.
In another embodiment, the reaction of step (1) is carried out at an absolute pressure of 200kPa to 500 kPa.
In another embodiment, step (2) is performed in a different reaction vessel than step (1).
In another embodiment, said step (2) is performed in more than one reaction vessel.
In another embodiment, if step (2) is performed in more than one reaction vessel, the temperature, pressure, and depressurization rate are controlled differently in each reaction vessel.
Accordingly, the present invention provides a process for producing polyglycolic acid which is efficient and safe, can effectively improve the yield of the product, and can effectively shorten the reaction cycle.
Detailed Description
The inventors of the present invention have conducted extensive and intensive studies and found that glycolic acid monomers or glycolate monomers and polyglycolic acid having a certain molecular weight are used as raw materials, and the polyglycolic acid having a certain molecular weight can undergo a depolymerization reaction with a monomer not participating in the esterification polycondensation reaction at a certain temperature (e.g., about 180-, thus being beneficial to reducing the residual quantity of the monomers in the reaction system and improving the monomer conversion rate. On the basis of this, the present invention has been completed.
Specifically, the preparation method of polyglycolic acid provided by the invention comprises the following steps:
in a first step, glycolic acid monomers are mixed withOr glycolate monomers and molecular weight Mw' mixing polyglycolic acid of 1 ten thousand or more, reacting to obtain molecular weight Mw1Material 400-;
in a second step, the molecular weight M is measuredw1The material of 400-1000 is subjected to step heating polymerization to obtain the polyglycolic acid product.
In one embodiment of the present invention, the polyglycolic acid used in the first step has a molecular weight Mw' may be 100000 or less, preferably 50000 or less, such as, but not limited to, 10000-50000 and the like.
The inventors have found that the molecular weight M of the system material in the first stepw1Relative to Mw' to the contrary, it is gradually reduced until the molecular weight Mw1Reducing the temperature to 400-1000, and then carrying out the subsequent second-step stage temperature-rising polymerization.
In one embodiment of the present invention, in the first step, the material may be sampled periodically, and the molecular weight M of the material may be measured by end group analysisw1Up to the measured molecular weight Mw1Up to 400-.
In the first step, the monomer which does not participate in the esterification polycondensation reaction can break the long chain of the polyglycolic acid into short chains and can be combined into the short chains, so that the monomer amount of a reaction system is reduced, and the utilization rate of the monomer is improved.
In one embodiment of the present invention, the molecular weight M is obtained in the first stepw1The weight of unreacted glycolic acid monomer and/or glycolate ester monomer in the 400-1000 feed is no more than 5.0 wt.%, preferably no more than 3.0 wt.%, more preferably no more than 2.0 wt.%, most preferably no more than 1.0 wt.%, such as, but not limited to, 0.01-4.0 wt.%, 0.02-0.8 wt.%, 0.03-0.3 wt.%, 0.04-0.1 wt.%, 0.05-0.6 wt.%, etc., of the initial charge.
The raw materials involved in the reaction in the first step also include a catalyst.
In one embodiment of the present invention, the catalyst is an oxide, a halide, or an organic acid salt of tin, or an oxide, a halide, or an organic acid salt of antimony, or an oxide, a halide, or an organic acid salt of zinc, or an oxide, a halide, or an organic acid salt of aluminum, or a composite catalyst of two or more of the foregoing.
Preferably, the catalyst may be selected from one or more of the following: stannous octoate, stannous chloride, stannic lactate, antimony trioxide, diethyl zinc, and zinc acetate dihydrate.
In one embodiment of the present invention, the amount of the catalyst is 0.01 to 0.1% by mass based on the glycolic acid monomer and/or glycolic acid ester monomer.
In one embodiment of the present invention, the glycolate based monomer may be selected from methyl glycolate, ethyl glycolate or n-butyl glycolate, preferably methyl glycolate.
In one embodiment of the present invention, the reaction temperature of the first step is 180-.
In one embodiment of the present invention, after the first step is carried out at 200 ℃ and 500kPa for 2-4 hours, the pressure is reduced to normal pressure, and then the temperature is raised to about 220 ℃ under normal pressure for 1-2 hours.
In one embodiment of the present invention, the amount of polyglycolic acid used in the first step is 5 to 50%, preferably 10 to 20% by mass of the glycolic acid monomer and/or glycolic acid ester monomer.
In one embodiment of the present invention, the polyglycolic acid used in the above-mentioned first step may be a partial polyglycolic acid product obtained in the second step.
In one embodiment of the present invention, the first step is carried out in a first reactor, for example, but not limited to, reacting glycolic acid monomer and/or glycolate ester monomer, catalyst and molecular weight Mw' putting more than 1 ten thousand polyglycolic acid into a first reaction kettle together for reaction, and making M of materials in the first reaction kettlew1Up to 400-.
The method provided by the invention can be carried out by serially connected reaction kettles. In one embodiment of the present invention, the second step is carried out in another reaction vessel connected in series with the first reaction vessel used in the first step; the number of the reaction kettles for performing the second step can be more than two, and the two reaction kettles are connected in series, for example, the second reaction kettle is connected in series with the first reaction kettle for performing the first step, the third reaction kettle is connected in series with the second reaction kettle, and so on until reaching the Nth reaction kettle.
In one embodiment of the present invention, the temperature in the last reaction vessel in the second step is controlled at 220 ℃ to 225 ℃, the absolute pressure in the reaction vessel is reduced to less than or equal to 2kPa at the rate of 2-4kPa per minute, and the reaction is maintained for 50-70 min.
In one embodiment of the present invention, the temperature in the last reaction vessel of the second step is controlled to be 220 ℃ and 225 ℃, the absolute pressure in the reaction vessel is reduced to less than or equal to 2kPa at the rate of 2-4kPa reduction per minute, and the unreacted glycolic acid monomer and/or glycolic acid ester monomer are/is removed in vacuum to keep reacting for 50-70 min.
In one embodiment of the present invention, the first step is carried out in the first reaction vessel, the second step is carried out in the second and third reaction vessels, the temperature of the second reaction vessel is controlled at 220 ℃ and the absolute pressure in the reaction vessel is reduced to 40-60kPa at the rate of reducing 2-4kPa per minute, and unreacted glycolic acid monomer and/or glycolic acid ester monomer are removed in vacuum to keep reacting for 110-130 min.
In one embodiment of the invention, the first step is carried out in the first reaction kettle, and the second step is carried out in the second to fourth reaction kettles, wherein the temperature of the second reaction kettle is controlled to be 204-220 ℃, the absolute pressure in the reaction kettle is reduced to 50-60kPa at the rate of reducing 2-4kPa per minute, and unreacted glycolic acid monomer and/or glycolic acid ester monomer are removed in vacuum to keep reacting for 40-60 min; the temperature of the third reaction kettle is controlled to be 210-220 ℃, the absolute pressure in the reaction kettle is reduced to 10-30kPa at the rate of reducing 2-4kPa per minute, and unreacted glycolic acid monomer and/or glycolic acid ester monomer are removed in vacuum to keep reacting for 70-90 min.
In one embodiment of the present invention, the first step is performed in the first reaction vessel, and the second step is performed in the second to fifth reaction vessels, wherein the temperature of the second reaction vessel is controlled to 203-; the temperature of the third reaction kettle is controlled to be 208-220 ℃, the absolute pressure in the reaction kettle is reduced to 30-50kPa at the rate of reducing 2-4kPa per minute, and unreacted glycolic acid monomer and/or glycolic acid ester monomer are removed in vacuum to keep reacting for 40-50 min; the temperature of the fourth reaction kettle is controlled to be 215-220 ℃, the absolute pressure in the reaction kettle is reduced to 10-20kPa at the rate of reducing 2-4kPa per minute, and unreacted glycolic acid monomer and/or glycolic acid ester monomer are removed in vacuum to keep reacting for 40-60 min.
The reaction vessels used in the first and second steps have substantially similar volumes, depending on the starting reaction material amounts.
The molecular weight of the polyglycolic acid product obtained in the above second step is not less than 3 ten thousand, preferably not less than 3.3 ten thousand.
To make the features and effects of the present invention comprehensible to those skilled in the art, general description and definitions are made below with reference to terms and expressions mentioned in the specification and claims. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
The theory or mechanism described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, i.e., the present disclosure may be practiced without limitation to any particular theory or mechanism.
All features defined herein as numerical ranges or percentage ranges, such as values, amounts, levels and concentrations, are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to cover and specifically disclose all possible subranges and individual numerical values (including integers and fractions) within the range.
Any numerical value inherently contains certain standard deviations found in their respective testing measurements. As used herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range. Alternatively, the term "about" means that the actual value falls within the acceptable standard error of the mean, as considered by those skilled in the art. Except in the experimental examples, or where otherwise expressly indicated, it is to be understood that all ranges, amounts, values and percentages herein used (e.g., to describe amounts of materials, length of time, temperature, operating conditions, quantitative ratios, and the like) are to be modified by the word "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, these numerical parameters are to be understood as meaning the number of significant digits recited and the number resulting from applying ordinary carry notation.
The features mentioned above with reference to the invention, or the features mentioned with reference to the embodiments, can be combined arbitrarily. All features disclosed in this specification may be combined in any combination, provided that there is no conflict between such features and the combination, and all possible combinations are to be considered within the scope of the present specification. Each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, the features disclosed are merely generic examples of equivalent or similar features.
The main advantages of the invention are:
1. the preparation method provided by the invention can effectively reduce the residual amount of the monomer which does not participate in the reaction, and improve the conversion rate of the monomer.
2. The polyglycolic acid prepared by the preparation method provided by the invention has high molecular weight which can reach about 4-5 ten thousand, even more than 5 ten thousand, and good molding processability.
3. The preparation method provided by the invention can effectively shorten the time of the whole reaction process and obviously reduce the energy consumption.
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers. All percentages, ratios, proportions, or parts are by weight unless otherwise specified. The units in weight volume percent in the present invention are well known to those skilled in the art and refer to, for example, the weight (g) of solute in 100ml of solution. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention. The preferred embodiments and materials described herein are intended to be exemplary only.
It is noted that in the following comparative examples and examples, the molecular weight was measured by end group analysis for the material having a molecular weight of less than 1000, and the molecular weight was measured by Gel Permeation Chromatography (GPC) for the material having a molecular weight of more than 1000.
End group analysis is a method conventional in the art for measuring molecular weight, and the number average molecular weight is measured, and the associated test method can be as follows: taking a sample to be detected (mass is M), adopting acetonitrile as a solvent, mixing the sample to be detected and the acetonitrile according to the mass ratio of 1:20, dissolving the sample to be detected in the acetonitrile solvent, adopting phenolphthalein as an indicator, adopting 0.1mol/L standard NaOH solution for titration, obtaining the molar weight N of-COOH in the sample by converting the amount of the consumed standard NaOH solution when reaching a titration end point, and obtaining the number average molecular weight M of the sample to be detected by calculating the ratio of M/Nn. Based on the method, the number average molecular weight of the material with the molecular weight less than 1000 can be accurately measured. Due to the problem of measurement accuracy of a GPC instrument, for materials with molecular weights less than 1000, the measurement result often has large fluctuation if GPC is adopted for measurement, namely, the measurement is not easy to be calibrated.
The molecular weight of the material with the molecular weight of more than 1000 can be measured by adopting a GPC instrument, and the specific test method is as follows: a0.2 g sample of PGA was dissolved in 100mL of hexafluoroisopropanol solution having a sodium trifluoroacetate content of 5mmol/L, filtered through a polytetrafluoroethylene filter having a pore size of 0.4. mu.m, and 20. mu.L of the filtrate was introduced into an "LC-20 AD GPC" sample injector manufactured by Shimadzu (Japan) under test conditions: the column temperature is 40 ℃; eluent: hexafluoroisopropanol with 5mmol/L of sodium trifluoroacetate dissolved therein; the flow rate is 1 mL/min; a detector: an RI detector; and (3) correction: five different standards of polymethyl methacrylate with molecular weights varying between 7000 and 200000 were used for molecular weight correction. Molecular weights were determined based on the GPC method described above.
Comparative example 1 (conventional two pot process):
adding 3000g of methyl glycolate and 1.8g of antimony trioxide into a first pressure-resistant reaction kettle (volume is 5L), carrying out polycondensation reaction at 500kPa and 200 ℃, reacting for about 4 hours, removing about 533g of methanol, then reducing the pressure to normal pressure, then heating to 220 ℃ at normal pressure, reacting for about 2 hours at normal pressure to further remove the methanol, removing about 320g of the methanol, sampling, and measuring M of materials in the reaction kettle by adopting an end group analysis methodw1About 486, subjecting the sample to a gas chromatography analysis test, measuring unreacted methyl glycolate monomer in the contents of the first pressure resistant reactor to be about 16% of the initial charge amount thereof, subsequently introducing the contents into the second pressure resistant reactor to carry out a final polymerization reaction, controlling the reaction temperature to 220 ℃, reducing the absolute pressure in the second pressure resistant reactor to 2kPa or less at a rate of reducing 2kPa per minute by using a vacuum pump, removing the unreacted methyl glycolate monomer in vacuo to further promote the polymerization reaction, maintaining the reaction for 70min, removing about 997g of the contents in a cumulative manner under a negative pressure and a vacuum to obtain about 1083g of polyglycolic acid, and measuring the M by GPC to obtain about 1083g of polyglycolic acidwAbout 1.82 ten thousand. The theoretical polyglycolic acid production amount was 1933g calculated based on the charged methyl glycolate, and therefore, the yield of polyglycolic acid obtained in this comparative example was: the actual yield/theoretical yield was 1083/1933 × 100%: 56.03%. The time required for the process flow of this comparative example was about 430 min.
Example 1 (inventive two pot process):
into a first pressure resistant reaction vessel (volume: 5L), 3000g of methyl glycolate, 1.8g of antimony trioxide and M were chargedw' about 1.6 million of polyglycolic acid 300g, reacting at 500kPa, 200 ℃ for about 2.5 hours, removing about 471g of methanol, then reducing the pressure to normal pressure, then raising the temperature to 220 ℃ under normal pressure, reacting at normal pressure for about 1 hour to further remove methanol, removing about 136g of methanol, taking a sample, and measuring the M of the contents of the reaction vessel by end group analysisw1About 620, the sample was subjected to gas chromatography analysis to determine the secondUnreacted methyl glycolate monomer in the material in the first pressure resisting reactor in the amount of 0.7% of the initial material amount, final polymerization in the second pressure resisting reactor at 220 deg.c, vacuum pump to lower the absolute pressure in the second pressure resisting reactor to 2kPa or less, vacuum elimination of unreacted methyl glycolate monomer to promote polymerization and maintaining the reaction for about 66min, and negative pressure and vacuum accumulation elimination of material in the amount of about 887g to obtain polyglycolic acid in about 1746g, and GPC measurement of M to obtain polyglycolic acid with M of about 0.7% of thatwAbout 3.36 million. The theoretical polyglycolic acid yield was 1933g calculated based on methyl glycolate charged, and therefore, the yield of polyglycolic acid produced in this example was: the actual yield/theoretical yield after elimination of PGA as the reaction raw material was (1746-. The time required for the process flow of this example was about 276 min.
Comparative example 2 (conventional three pot process):
adding 3000g of methyl glycolate and 1.3g of stannous octoate and 1.6g of zinc acetate dihydrate into a first pressure-resistant reaction kettle (with the volume of 5L), carrying out polycondensation reaction at the temperature of 190 ℃ under 450kPa for about 7 hours, removing 522g of methanol, then reducing the pressure to normal pressure, then raising the temperature to 225 ℃ under normal pressure, reacting for about 4 hours under normal pressure to further remove the methanol, removing 328g of the methanol, sampling, and measuring the M of the materials in the reaction kettle by adopting an end group analysis methodw1About 502, performing a gas chromatography analysis test on a sample, measuring that unreacted methyl glycolate monomer in the material in the first pressure-resistant reaction kettle is about 20% of the initial feeding amount, then introducing the material into the second pressure-resistant reaction kettle to perform an intermediate polymerization reaction, controlling the reaction temperature to be 220 ℃, reducing the absolute pressure in the second pressure-resistant reaction kettle to 50kPa at a rate of reducing 2kPa per minute by using a vacuum pump, removing the unreacted methyl glycolate monomer in vacuum, further promoting the polymerization reaction, maintaining the reaction for 130min, removing about 400g of the material at negative pressure, then introducing the material into the third pressure-resistant reaction kettle to perform a final polymerization reaction, controlling the reaction temperature to be 225 ℃, reducing the absolute pressure in the third pressure-resistant reaction kettle to less than or equal to 2kPa at a rate of reducing 2kPa per minute by using a vacuum pump, and removing unreacted ethylene under vacuumMethyl alkyd monomer for further promoting polymerization reaction, maintaining the reaction for 60min, removing 597g under negative pressure and vacuum to obtain 1126g of polyglycolic acid, and measuring its M by GPCwAbout 2.07 ten thousand. The theoretical polyglycolic acid production amount was 1933g calculated based on the charged methyl glycolate, and therefore, the yield of polyglycolic acid obtained in this comparative example was: the actual yield/theoretical yield is 1126/1933 × 100% and 58.25%. The time required for the process flow of this comparative example was about 850 min.
Example 2 (three pot process of the invention):
into a first pressure resistant reaction vessel (volume: 5L), 3000g of methyl glycolate, 1.3g of stannous octoate, 1.6g of zinc acetate dihydrate, and M were chargedw' about 3.1 million polyglycolic acid (300 g) was reacted at 300kPa and 180 ℃ for about 3.2 hours to remove about 417g of methanol, followed by depressurization to atmospheric pressure, then heating to 220 ℃ under atmospheric pressure for about 2 hours to further remove methanol, removing about 136g of methanol, and sampling to determine M of contents in the reaction vessel by end group analysisw1About 619, performing a gas chromatography analysis test on a sample, measuring that unreacted methyl glycolate monomer in the material in the first pressure-resistant reaction kettle is about 0.9% of the initial charging amount, then introducing the material into the second pressure-resistant reaction kettle to perform an intermediate polymerization reaction, controlling the reaction temperature to be 220 ℃, reducing the absolute pressure in the second pressure-resistant reaction kettle to 50kPa at a rate of reducing 2kPa per minute by using a vacuum pump, removing the unreacted methyl glycolate monomer in vacuum, further promoting the polymerization reaction, maintaining the reaction for 108min, removing about 285g of the material at negative pressure, then introducing the material into the third pressure-resistant reaction kettle to perform a final polymerization reaction, controlling the reaction temperature to be 225 ℃, reducing the absolute pressure in the third pressure-resistant reaction kettle to 2kPa or less at a rate of reducing 2kPa per minute by using a vacuum pump, removing the unreacted methyl glycolate monomer in vacuum, further promoting the polymerization reaction, maintaining the reaction for 56min, removing 703g of material under negative pressure and vacuum to obtain 1715g of polyglycolic acid, whose M is measured by GPCwAbout 4.27 ten thousand. The theoretical polyglycolic acid yield was 1933g calculated based on methyl glycolate charged, and therefore, the yield of polyglycolic acid produced in this example was: reject asThe actual yield/theoretical yield after PGA of the reaction raw material was (1715-. The time required for the process flow of this example is about 476 min.
Comparative example 3 (conventional four pot process):
3000g of methyl glycolate, 0.5g of antimony trioxide, 0.7g of diethyl zinc and 1.2g of stannous octoate are put into a first pressure-resistant reaction kettle (volume is 5L), polycondensation reaction is carried out at 420kPa and 198 ℃ for about 3.6 hours, about 510g of methanol is removed, then pressure is reduced to normal pressure, then temperature is raised to 220 ℃ at normal pressure, reaction is carried out for about 2 hours at normal pressure to further remove the methanol, about 338g of methanol is removed, sampling is carried out, and M of materials in the reaction kettle is measured by adopting an end group analysis methodw1About 475, performing a gas chromatography analysis test on the sample, measuring that unreacted methyl glycolate monomer in the material in the first pressure-resistant reaction kettle is about 12% of the initial feeding amount, then introducing the material into the second pressure-resistant reaction kettle to perform an intermediate polymerization reaction, controlling the reaction temperature to be 205 ℃, reducing the absolute pressure in the second pressure-resistant reaction kettle to 50kPa at a rate of reducing 2kPa per minute by using a vacuum pump, removing the unreacted methyl glycolate monomer in a vacuum manner, further promoting the polymerization reaction, maintaining the reaction for 78min, removing about 356g of the material at a negative pressure, introducing the material into the third pressure-resistant reaction kettle to continue the intermediate polymerization reaction, controlling the reaction temperature to be 210 ℃, reducing the absolute pressure in the third pressure-resistant reaction kettle to 10kPa at a rate of reducing 2kPa per minute by using the vacuum pump, removing the unreacted methyl glycolate monomer in a vacuum manner, further promoting the polymerization reaction, keeping the reaction for 106min, removing about 292g of materials under negative pressure, finally introducing the materials into a fourth pressure-resistant reaction kettle for final polymerization reaction, controlling the reaction temperature to be 220 ℃, reducing the absolute pressure in the fourth pressure-resistant reaction kettle to be less than or equal to 2kPa by adopting a vacuum pump at the rate of reducing 2kPa per minute, removing unreacted methyl glycolate monomer under vacuum, further promoting the polymerization reaction, keeping the reaction for 90min, removing about 307g of materials under negative pressure and vacuum cumulatively to obtain about 1150g of polyglycolic acid, and measuring the M by GPC (GPC)wAbout 2.26 ten thousand. The yield of polyglycolic acid calculated from methyl glycolate charged was 1933g, and therefore, the yield of polyglycolic acid obtained in this comparative example wasThe ratio is: the actual yield/theoretical yield is 1150/1933 × 100% ═ 59.49%. The time required for the process flow of this comparative example was about 610 min.
Example 3 (four pot process of the invention):
into a first pressure resistant reaction vessel (volume: 5L), 3000g of methyl glycolate, 0.5g of antimony trioxide, 0.7g of diethyl zinc, 1.2g of stannous octoate, and M were chargedw' about 1.3 million of polyglycolic acid (150 g) was reacted at 420kPa, 198 ℃ for about 2.2 hours, about 426g of methanol was removed, followed by depressurization to atmospheric pressure, then warming to 220 ℃ under atmospheric pressure, and atmospheric pressure reaction for about 1.6 hours to further remove methanol, about 130g of methanol was removed, and a sample was taken to determine M of the contents of the reaction vessel by end group analysisw1About 647, subjecting the sample to gas chromatography analysis test, measuring unreacted methyl glycolate monomer in the first pressure-resistant reaction vessel to be about 0.4% of its initial charge, then introducing the material into a second pressure-resistant reaction vessel to perform intermediate polymerization reaction, controlling the reaction temperature to be 205 ℃, reducing the absolute pressure in the second pressure-resistant reaction vessel to 50kPa at a rate of reducing 2kPa per minute by using a vacuum pump, removing unreacted methyl glycolate monomer in vacuum, further promoting the polymerization reaction, maintaining the reaction for 40min, removing about 217g of the material at negative pressure, introducing the material into a third pressure-resistant reaction vessel to continue the intermediate polymerization reaction, controlling the reaction temperature to be 210 ℃, reducing the absolute pressure in the third pressure-resistant reaction vessel to 10kPa at a rate of reducing 2kPa per minute by using a vacuum pump, removing unreacted methyl glycolate monomer in vacuum, further promoting the polymerization reaction, keeping the reaction for 70min, removing about 352g of materials under negative pressure, finally introducing the materials into a fourth pressure-resistant reaction kettle for final polymerization reaction, controlling the reaction temperature to be 220 ℃, reducing the absolute pressure in the fourth pressure-resistant reaction kettle to be less than or equal to 2kPa by adopting a vacuum pump at the rate of reducing 2kPa per minute, removing unreacted methyl glycolate monomer under vacuum, further promoting the polymerization reaction, keeping the reaction for 60min, removing about 403g of materials under negative pressure and vacuum cumulatively to obtain about 1562g of polyglycolic acid, and measuring the M by GPC (GPC)wAbout 4.98 ten thousand. The theoretical polyglycolic acid yield was 1933g calculated based on methyl glycolate charged, and therefore, this example was carried outThe yield of polyglycolic acid prepared in example was: the actual yield/theoretical yield after elimination of PGA as the reaction raw material was (1562-. The time required for the process flow of this example was about 398 min.
Example 3-1
This example was further modified based on the above example 3 in that M produced in the fourth pressure resistant reaction vessel in example 3 was charged into the first pressure resistant reaction vessel (volume: 5L) with 3000g of methyl glycolate, 0.5g of antimony trioxide, 0.7g of diethyl zinc and 1.2g of stannous octoate as reaction raw materialsw(i.e., corresponding to M)w') about 600g of polyglycolic acid of about 4.98 ten thousand was returned to the first pressure resistant reaction vessel through a return line, followed by reaction at 200 ℃ under 500kPa for about 3 hours with about 430g of methanol removed, followed by pressure reduction to atmospheric pressure, followed by temperature increase to 220 ℃ under atmospheric pressure with about 2 hours of reaction to further remove methanol with about 122g of methanol removed, sampling, and M of the contents of the reaction vessel was measured by end group analysisw1About 490, a gas chromatography analysis test was performed on the sample, and it was determined that unreacted methyl glycolate monomer in the material in the first pressure-resistant reaction vessel was about 0.5% of its initial charge amount, then the material was introduced into the second pressure-resistant reaction vessel to perform an intermediate polymerization reaction, the reaction temperature was controlled at 215 ℃, the absolute pressure in the second pressure-resistant reaction vessel was reduced to 60kPa at a rate of reducing 4kPa per minute using a vacuum pump, the unreacted methyl glycolate monomer was removed in vacuo, the polymerization reaction was further promoted, the reaction was maintained for 60min, about 244g of the material was removed at negative pressure, then the material was introduced into the third pressure-resistant reaction vessel to continue the intermediate polymerization reaction, the reaction temperature was controlled at 220 ℃, the absolute pressure in the third pressure-resistant reaction vessel was reduced to 30kPa at a rate of reducing 4kPa per minute using a vacuum pump, the unreacted methyl glycolate monomer was removed in vacuo, further promoting the polymerization reaction, keeping the reaction for 90min, removing 353g of material under negative pressure, finally introducing the material into a fourth pressure-resistant reaction kettle for final polymerization reaction, controlling the reaction temperature to 225 ℃, reducing the absolute pressure in the fourth pressure-resistant reaction kettle to be less than or equal to 2kPa by adopting a vacuum pump at the rate of reducing 3kPa per minute, and removing unreacted methyl glycolate under vacuumEster monomer to further promote polymerization and maintain the reaction for 70min, and removing about 403g of material under vacuum to obtain about 1984g of polyglycolic acid whose M is measured by GPCwIs about 5.07. The theoretical polyglycolic acid yield was 1933g calculated based on methyl glycolate charged, and therefore, the yield of polyglycolic acid produced in this example was: the actual yield/theoretical yield after elimination of PGA as the reaction raw material was 71.60% (1984-600)/1933X 100%. The time required for the process flow of this embodiment is about 520 min.
Comparative example 4 (conventional five pot process):
adding 3000g of methyl glycolate and 0.3g of stannous octoate into a first pressure-resistant reaction kettle (with the volume of 5L), carrying out polycondensation reaction at 500kPa and 200 ℃, reacting for about 6 hours, removing about 506g of methanol, then reducing the pressure to normal pressure, then heating to 220 ℃ at normal pressure, reacting for about 4 hours at normal pressure to further remove the methanol, removing about 345g of the methanol, sampling, and measuring the M of the materials in the reaction kettle by using an end group analysis methodw1To about 662, a gas chromatography analysis test was performed on the sample, and it was determined that unreacted methyl glycolate monomer in the material in the first pressure resistant reactor was about 10% of its initial charge amount, then the material was introduced into the second pressure resistant reactor to perform an intermediate polymerization reaction, the reaction temperature was controlled at 220 ℃, the absolute pressure in the second pressure resistant reactor was reduced to 80kPa at a rate of 2kPa per minute reduction using a vacuum pump, the unreacted methyl glycolate monomer was removed under vacuum, the polymerization reaction was further accelerated, the reaction was maintained for 56min, about 208g of the material was removed under negative pressure, then the material was introduced into the third pressure resistant reactor to continue the intermediate polymerization reaction, the reaction temperature was controlled at 220 ℃, the absolute pressure in the third pressure resistant reactor was reduced to 50kPa at a rate of 2kPa per minute reduction using a vacuum pump, the unreacted methyl glycolate monomer was removed under vacuum, further promoting the polymerization reaction, keeping the reaction for 68min, removing about 223g of the material under negative pressure, then introducing the material into a fourth pressure-resistant reaction kettle to continue the intermediate polymerization reaction, controlling the reaction temperature to be 220 ℃, reducing the absolute pressure in the fourth pressure-resistant reaction kettle to 20kPa by adopting a vacuum pump at the speed of reducing 2kPa per minute, removing the unreacted methyl glycolate monomer under vacuum, and further promotingCarrying out polymerization reaction, keeping the reaction for 73min, removing about 246g of materials under negative pressure, finally introducing the materials into a fifth pressure-resistant reaction kettle for final polymerization reaction, controlling the reaction temperature to be 220 ℃, reducing the absolute pressure in the fifth pressure-resistant reaction kettle to be less than or equal to 2kPa by adopting a vacuum pump at the speed of reducing 2kPa per minute, removing unreacted methyl glycolate monomer in vacuum, further promoting the polymerization reaction, keeping the reaction for 90min, removing about 317g of materials under negative pressure and vacuum cumulatively to obtain about 1109g of polyglycolic acid, and measuring the M by GPC (GPC)wAbout 2.42 ten thousand. The theoretical polyglycolic acid production amount was 1933g calculated based on the charged methyl glycolate, and therefore, the yield of polyglycolic acid obtained in this comparative example was: the actual yield/theoretical yield was 1109/1933 × 100% ═ 57.37%. The time required for the process flow of this comparative example was about 887 min.
Example 4 (five pot process of the invention):
3000g of methyl glycolate, 0.3g of stannous octoate and M were put into a first pressure resistant reaction vessel (volume: 5L)w' about 4.9 million of polyglycolic acid (1500 g) was reacted at 200kPa and 200 ℃ for about 2.5 hours to remove about 413g of methanol, followed by depressurization to atmospheric pressure, then heating to 220 ℃ under atmospheric pressure for about 1 hour to further remove methanol, removing about 146g of methanol, sampling, and measuring M of contents in the reaction vessel by end group analysisw1About 982, performing a gas chromatography analysis test on the sample, measuring that unreacted methyl glycolate monomer in the material in the first pressure-resistant reaction kettle is about 0.2% of the initial feeding amount, then introducing the material into the second pressure-resistant reaction kettle to perform an intermediate polymerization reaction, controlling the reaction temperature to be 220 ℃, reducing the absolute pressure in the second pressure-resistant reaction kettle to 80kPa at a rate of reducing 2kPa per minute by using a vacuum pump, removing the unreacted methyl glycolate monomer in vacuum, further promoting the polymerization reaction, maintaining the reaction for 38min, removing about 156g of the material at negative pressure, introducing the material into the third pressure-resistant reaction kettle to continue the intermediate polymerization reaction, controlling the reaction temperature to be 220 ℃, reducing the absolute pressure in the third pressure-resistant reaction kettle to 50kPa at a rate of reducing 2kPa per minute by using a vacuum pump, removing the unreacted methyl glycolate monomer in vacuum, further promote polymerizationKeeping the reaction for 45min, removing about 206g of materials under negative pressure, then introducing the materials into a fourth pressure-resistant reaction kettle to continue to perform intermediate polymerization reaction, controlling the reaction temperature to be 220 ℃, reducing the absolute pressure in the fourth pressure-resistant reaction kettle to 20kPa at the rate of reducing 2kPa per minute by using a vacuum pump, removing unreacted methyl glycolate monomer in vacuum, further promoting the polymerization reaction, keeping the reaction for 60min, removing about 243g of materials under negative pressure, finally introducing the materials into a fifth pressure-resistant reaction kettle to perform final polymerization reaction, controlling the reaction temperature to be 220 ℃, reducing the absolute pressure in the fifth pressure-resistant reaction kettle to be less than or equal to 2kPa at the rate of reducing 2kPa by using the vacuum pump, removing the unreacted methyl glycolate monomer in vacuum, further promoting the polymerization reaction, keeping the reaction for 70min, and removing about 362g of materials under negative pressure and vacuum cumulatively to obtain about 2904g of polyglycolic acid, measured by GPC for MwAbout 4.74 ten thousand. The theoretical polyglycolic acid yield was 1933g calculated based on methyl glycolate charged, and therefore, the yield of polyglycolic acid produced in this example was: the actual yield/theoretical yield after elimination of PGA as the reaction raw material was (2904-. The time required for the process flow of this example was about 423 min.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the scope of the invention, which is defined by the claims appended hereto, and any other technical entity or method that is encompassed by the claims as broadly defined herein, or equivalent variations thereof, is contemplated as being encompassed by the claims.
Claims (10)
1. A method for preparing polyglycolic acid, comprising the steps of:
(1) reacting glycolic acid monomer and/or glycolate monomer with molecular weight Mw'polyglycolic acid of' is mixed and reacted to give a molecular weight Mw1The material (2);
(2) molecular weight is Mw1Polymerizing the materials to obtain polyglycolic acid;
the M isw' is a number of 1 ten thousand or more.
2. The method of claim 1, wherein M isw' is a number of 1 to 10 ten thousand.
3. The method of claim 1, wherein M isw' is a number of 1 to 5 ten thousand.
4. The process according to claim 1, wherein the molecular weight of the glycolic acid monomer or glycolic acid ester monomer of step (1) is Mw' the amount of polyglycolic acid is 5-50%; preferably 10-20%.
5. The method of claim 1, wherein M isw1Is 400- & gt 1000.
6. The method according to claim 1, wherein the molecular weight in step (1) is MwThe polyglycolic acid of' is derived from the polyglycolic acid obtained in step (2).
7. The method according to claim 1, wherein the reaction in step (1) is carried out at 180-200 ℃.
8. The method according to claim 1, wherein the reaction in the step (1) is carried out at an absolute pressure of 200kPa to 500 kPa.
9. The production method according to any one of claims 1 to 8, wherein the step (2) is carried out in a reaction tank different from that of the step (1).
10. The method of claim 9, wherein step (2) is performed in more than one reaction vessel.
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| JP2009040917A (en) * | 2007-08-09 | 2009-02-26 | Kureha Corp | Polyglycolic acid resin composition, manufacturing method therefor, and molding thereof |
| CN103781833A (en) * | 2011-08-19 | 2014-05-07 | 乌德伊万塔-费希尔有限公司 | Process and apparatus for recovering lactide from polylactide or glycolide from polyglycolide |
| CN107177032A (en) * | 2016-03-11 | 2017-09-19 | 上海浦景化工技术股份有限公司 | The method that HMW polyglycolic acid is prepared by glycolic or methyl glycollate |
| CN111087580A (en) * | 2018-10-23 | 2020-05-01 | 中国石油化工股份有限公司 | Method for preparing polyglycolic acid |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009040917A (en) * | 2007-08-09 | 2009-02-26 | Kureha Corp | Polyglycolic acid resin composition, manufacturing method therefor, and molding thereof |
| CN103781833A (en) * | 2011-08-19 | 2014-05-07 | 乌德伊万塔-费希尔有限公司 | Process and apparatus for recovering lactide from polylactide or glycolide from polyglycolide |
| CN107177032A (en) * | 2016-03-11 | 2017-09-19 | 上海浦景化工技术股份有限公司 | The method that HMW polyglycolic acid is prepared by glycolic or methyl glycollate |
| CN111087580A (en) * | 2018-10-23 | 2020-05-01 | 中国石油化工股份有限公司 | Method for preparing polyglycolic acid |
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