Guanyl ligands, catalysts, polyglycolic acid resins, and methods of making and using the same

Abstract

The application discloses a guanidine-based ligand, a catalyst, a polyglycolic acid resin and a preparation method and application thereof. The guanidine-based ligand has the following structural formula: wherein R1 is located at an ortho position, a meta position or a para position of a guanidine group connected with a benzene ring; the R1 is selected from -(CH2)m-COOR4, m is selected from any integer from 0 to 10, and R4 is selected from C1-C10 alkyl; R2 and R3 are each independently selected from C1-C20 linear alkyl; or R2 and R3 are connected to form a structure of -(CH2) a , wherein a is selected from any integer from 3 to 10, and n is an integer greater than or equal to 1. The guanidine-based ligand is prepared, and the catalyst prepared by using the guanidine-based ligand has high stability and high catalytic activity; when the catalyst is used for preparing PGA, high-molecular-weight PGA can be obtained.

Description

Technical Field

[0001] This invention relates to the technical field of metal catalysts and the preparation of polyglycolic acid resins, and more specifically, to guanidine ligands, catalysts, polyglycolic acid resins, their preparation methods and applications. Background Technology

[0002] Polyglycolic acid (PGA) is a type of linear aliphatic polyester. High molecular weight PGA is typically prepared from glycolide, and the molecular weight can be adjusted to meet different application requirements. Due to its excellent gas barrier properties, superior machinability, and outstanding biodegradability, PGA is widely used in medical materials (surgical sutures and sustained-release drug capsules), packaging materials (inner linings), membrane materials (mulch films), and engineering plastics (petroleum industry).

[0003] The preparation of polyglycolic acid (PGA) involves a lengthy process, resulting in high manufacturing costs and limiting its further applications. The purification process of glycolide is the most time-consuming and solvent-intensive, a key factor contributing to PGA's high cost. This is because obtaining PGA requires high-purity glycolide raw materials. For example, the manufacturing method of aliphatic polyester in patent CN1703439A requires the glycolide raw material to have a moisture content below 50 ppm, an α-hydroxycarboxylic acid content below 100 ppm, and an α-hydroxycarboxylic acid oligomer content below 1000 ppm. Common catalysts for PGA include stannous chloride and stannous octoate. Since tin is a toxic metal, the amount of tin used in the polymerization reaction must be reduced. However, the polymerization reaction still requires a certain amount of catalyst. Resolving this contradiction is one of the challenges in preparing medical-grade PGA resin.

[0004] To address the biotoxicity of metal catalysts such as tin, organic guanidine, modified organic guanidine, and organic guanidine are generally used as catalysts. However, the resulting PGA has a low molecular weight, generally below 100,000, and organic guanidine metal salt catalysts suffer from complexation instability. Summary of the Invention

[0005] To address the problems in existing technologies, this invention proposes guanidine ligands, catalysts, polyglycolic acid resins, their preparation methods, and applications. This invention prepares a novel guanidine ligand, and the catalyst prepared from this ligand exhibits stable complexation and high catalytic activity. When used to prepare PGA, high molecular weight PGA can be obtained.

[0006] One objective of this invention is to provide a guanidine ligand having the following structural formula:

[0007]

[0008] R1 is located at the ortho, meta, or para position of the guanidinium group connected to the benzene ring;

[0009] R1 is selected from -(CH2)m-COOR4, m is selected from any integer from 0 to 10, and R4 is selected from C1-C10 alkyl groups;

[0010] R2 and R3 are each independently selected from C1-C20 straight-chain alkyl groups; or, R2 and R3 are linked to form -(CH2). a - structure, wherein a is selected from any integer from 3 to 10;

[0011] In -(CH2)n-, the value of n is an integer ≥1.

[0012] In the guanidinyl ligands described in this invention, preferably,

[0013] The R4 is selected from C1-C5 alkyl groups; and / or,

[0014] The m is selected from any integer from 0 to 5;

[0015] Preferably,

[0016] The R4 is selected from C1-C3 straight-chain alkyl groups; and / or,

[0017] The m is selected from any integer between 0 and 3;

[0018] More preferably, the R4 is selected from methyl.

[0019] In the guanidinyl ligands described in this invention, preferably,

[0020] R2 and R3 are each independently selected from C1-C10 straight-chain alkyl groups.

[0021] Preferably, R2 and R3 are each independently selected from C1-C5 straight-chain alkyl groups;

[0022] Preferably, R2 and R3 are each independently selected from C1-C3 straight-chain alkyl groups.

[0023] More preferably, R2 and R3 are each independently selected from -CH3 and -CH2-CH3;

[0024] or,

[0025] R2 and R3 are connected to form -(CH2). a - structure, where a is selected from any integer from 3 to 5.

[0026] In the guanidinyl ligands described in this invention, preferably,

[0027] In -(CH2)n-, n takes the value of any integer from 1 to 10;

[0028] Preferably, n takes the value of any integer from 2 to 6.

[0029] A second objective of this invention is to provide a method for preparing the guanidinium ligand described in one objective of this invention, comprising the following steps:

[0030] The compound shown in Formula 1, an organic base, and solvent A are mixed and then added to the compound shown in Formula 2 for reaction. After post-treatment, the guanidine ligand is obtained.

[0031] The compound represented by Formula 1 has the following general structural formula:

[0032]

[0033] The compound shown in Formula 2 has the following general structural formula:

[0034]

[0035] In the method for preparing the guanidinium ligand described in this invention, preferably,

[0036] The organic base is selected from organic amines, and preferably, the organic base is selected from triethylamine;

[0037] Solvent A is selected from nitrile solvents, and preferably, solvent A is MeCN;

[0038] The reaction includes a post-processing step, which preferably involves adding an inorganic alkali solution to the reaction product, followed by vacuum distillation, then adding another inorganic alkali solution, extraction, and drying. Preferably, the inorganic alkali in the inorganic alkali solution is selected from at least one of NaOH and KOH.

[0039] More preferably, the post-treatment involves adding NaOH solution, followed by vacuum distillation, then adding KOH solution, extraction, and drying.

[0040] More preferably,

[0041] The concentration of the NaOH solution is 1-5 mol / L;

[0042] The concentration of the KOH solution is 10-20 mol / L.

[0043] In the method for preparing the guanidinium ligand described in this invention, preferably,

[0044] The molar ratio of the organic base to the compound shown in Formula 1 is (1-10):1; preferably (1-2):1; and / or,

[0045] The concentration of the compound represented by Formula 1 in solvent A is 0.1-1 mol / L, preferably 0.5-0.7 mol / L; and / or,

[0046] The volume molar ratio of the compound shown in Formula 2 to the compound shown in Formula 1 is (1-11):1; preferably (2-8):1; and / or,

[0047] The reaction time is 3-10 hours; and / or,

[0048] The reaction was carried out at room temperature.

[0049] A third objective of this invention is to provide a catalyst comprising a complex formed from at least one of the guanidinium ligand described in one objective of this invention and a halide of metal M or an oxide of metal M;

[0050] The metal M is selected from at least one of Group IIA, Group IIB, Group IVA or Group VIII.

[0051] In the catalyst of the present invention, the guanidinium ligand is bonded to the M atom in the halide or oxide of metal M in accordance with the bonding mode of conventional organic guanidinium metal catalysts. Specifically, the M atom in the halide or oxide of metal M is bonded to the nitrogen atom and carbonyl oxygen atom in the guanidinium ligand to form a complex.

[0052] In the catalyst described in this invention, preferably,

[0053] In the catalyst, the molar ratio of the guanidinyl ligand to metal M is 1:(1-3), preferably 1:(1-1.5); and / or,

[0054] The metal M is selected from at least one of Zn, Mg, Ca, and Fe;

[0055] Preferably,

[0056] The halide of metal M is selected from at least one of magnesium chloride, zinc chloride, calcium chloride, magnesium bromide, and zinc bromide; and / or,

[0057] The oxide of metal M is selected from at least one of zinc oxide and magnesium oxide.

[0058] The fourth objective of this invention is to provide a method for preparing the catalyst described in the third objective of this invention, comprising the following steps:

[0059] The catalyst is obtained by reacting the guanidinium ligand with at least one of the halides of metal M and the oxides of metal M in solvent B, followed by post-treatment.

[0060] In the method for preparing the catalyst described in this invention, preferably,

[0061] In the reaction system, the molar volume ratio of guanidinyl ligand to solvent B is 1 mmol : (2 mL - 10 mL); and / or,

[0062] The molar ratio of the guanidinium ligand to metal M in the halide and / or oxide of metal M is 1:(1-3), preferably 1:(1-1.5); and / or,

[0063] Solvent B is selected from at least one of tetrahydrofuran, dichloromethane, trichloromethane, and acetonitrile, preferably tetrahydrofuran and acetonitrile; and / or,

[0064] The reaction temperature is 10-40℃; and / or,

[0065] The reaction time is 15 min to 2 h; and / or,

[0066] The post-treatment involved cooling the reaction product, crystallizing it, filtering it, and vacuum drying it to obtain the catalyst.

[0067] The fifth objective of this invention is to provide a method for preparing polyglycolic acid resin, comprising the following steps:

[0068] Under the catalysis of the catalyst described in objective three of this invention or the catalyst prepared by the preparation method described in objective four of this invention, glycolide and initiator react to generate polyglycolic acid resin.

[0069] The method for preparing polyglycolic acid resin according to the present invention preferably includes the following steps:

[0070] (1) Pre-reacting glycolide, catalyst and initiator;

[0071] (2) After the pre-reaction is completed, a post-reaction and post-treatment are carried out to obtain polyglycolic acid resin.

[0072] In the preparation method of polyglycolic acid resin according to the present invention, preferably,

[0073] The acid value of the glycolide is 2-100 mol / t, and the water content is 50-1000 ppm; and / or,

[0074] The initiator is selected from at least one of lauryl alcohol, decyl alcohol, decanediol, and undecyl alcohol.

[0075] In the preparation method of polyglycolic acid resin according to the present invention, preferably, in the reaction system,

[0076] The catalyst content is 100ppm-1000ppm, preferably 100ppm-500ppm; for example, 100, 150, 200, 250, 300, 400, 500ppm, or any range of any two of the above values; and / or,

[0077] The initiator content is 50-2000 ppm, preferably 300-500 ppm; for example, it is 50, 100, 150, 200, 250, 300, 350, 400, 500, 600, 700, 800, 900, 1000, 1200, 1400, 1600, 1800, 2000 ppm, or any range of any two of the above values.

[0078] In the preparation method of polyglycolic acid resin according to the present invention, preferably, the pre-reaction temperature is 80-130℃, more preferably 90-120℃; for example, 80, 90, 100, 110, 120, 130℃ and any range of any two of the above values; and / or,

[0079] The pre-reaction time is 1-2 hours, preferably 1-1.5 hours; for example, it is any range of 1, 1.5, 2 hours, or any two of the above values; and / or,

[0080] The temperature of the subsequent reaction is 130-230℃, preferably 190-220℃; for example, 130, 150, 170, 190, 200, 210, 230℃, and any range of any two of the above values; and / or,

[0081] The subsequent reaction time is 15 min to 5 h, preferably 15 min to 1 h; for example, it can be 15 min, 30 min, 60 min, 2 h, 3 h, 4 h, 5 h, or any range of any two of the above values; and / or,

[0082] The post-processing includes a devolatilization process, preferably...

[0083] The temperature for the devolatilization treatment is 200-230℃, preferably 210-220℃; for example, it is 200, 210, 220, 230℃, or any range of any two of the above values; and / or,

[0084] The devolatilization treatment time is 1 min to 1 h, preferably 10 min to 30 min; for example, 1 min, 5 min, 15 min, 30 min, 45 min, 60 min, or any range of any two of the above values; and / or,

[0085] The vacuum degree of the devolatilization treatment is 100Pa-50kPa, preferably 100Pa-200Pa.

[0086] The sixth objective of this invention is to provide a polyglycolic acid resin prepared by the preparation method described in the fifth objective of this invention.

[0087] In the polyglycolic acid resin of the present invention, preferably,

[0088] The polyglycolic acid resin contains less than 3 wt% glycolide, preferably less than 1.2 wt%; and / or,

[0089] The polyglycolic acid resin has a molecular weight of 100,000-300,000, preferably 148,000-246,000; and / or,

[0090] The intrinsic viscosity of the polyglycolic acid resin is 1.2-2.0 dL / g, preferably 1.6-1.8 dL / g.

[0091] The seventh objective of this invention is to provide the application of the polyglycolic acid resin described in the sixth objective of this invention in medical materials, packaging materials, membrane materials, and engineering plastics.

[0092] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0093] Compared with the prior art, the present invention has at least the following advantages:

[0094] The catalyst described in this invention contains metal M, including but not limited to low-toxicity or non-toxic metals such as Zn, Mg, Ca, and Fe. This solves the problem of the contradiction between the toxicity of medical-grade polyglycolic acid resin and the amount of catalyst used.

[0095] Existing organic guanidine catalysts typically have polymer molecular weights below 100,000, which are insufficient for their performance requirements. However, the guanidine-based metal catalyst of this invention has polymer molecular weights ranging from 100,000 to 300,000, meeting the spinning performance requirements.

[0096] The organic guanidine catalyst of the present invention not only contains N and O atoms, but also introduces -(CH2) atoms. n - The structure allows it to form larger rings when complexing with metals, resulting in lower ring tension and greater flexibility. This makes it easier for N and O to complex with metals, while also ensuring more stable complexation and higher catalytic activity. Detailed Implementation

[0097] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0098] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0099] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0100] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0101] Test method:

[0102] Intrinsic viscosity ([η]): Using hexafluoroisopropanol as solvent, the outflow time t of the pure solvent and the sample solution was measured using an Ubbelohde viscometer in a constant temperature water bath at 25°C. o t and t are obtained using the "one-point method" formula.

[0103] Residual content test: An Agilent 7890B gas chromatograph was used, with a DB-FFAP column. The initial column temperature was 160℃, the temperature was programmed, the column flow rate was 1 ml / min, the split ratio was 20:1, the injection port temperature was 300℃, and an FID detector was used with a detector temperature of 300℃.

[0104] Weight-average molecular weight determination: An Agilent PL50 gel permeation chromatography (GPC) system was used. The PGLA sample was dissolved in a hexafluoroisopropanol solution containing 5 mM sodium trifluoroacetate. The column temperature was set at 40℃; the hexafluoroisopropanol solution containing 5 mM sodium trifluoroacetate was used as the eluent; the flow rate was set at 1 mL / min of resin; and relative molecular mass correction was performed using five different standard polymethyl methacrylates to obtain the weight-average molecular weight (Mw).

[0105] Preparation Example 1

[0106] Preparation of guanidinyl ligands:

[0107] Anthranilyl ester (40 mmol, 1.0 eq.), triethylamine (40 mmol, 1.0 eq.), and dried MeCN (60 mL) were mixed thoroughly and then added dropwise to a solution of chloroformamidine hydrochloride (44 mmol, 1.1 eq.). The mixture was refluxed for 3 hours and cooled to room temperature. NaOH aqueous solution (40 mmol, 1.0 eq. in 20 mL H₂O) was added, and the solvent and triethylamine were evaporated under reduced pressure. Guanidine hydrochloride was deprotonated by adding KOH (50 mL, 50 wt%) to obtain the guanidine ligand. The guanidine ligand was extracted three times with 30 mL of MeCN and then dried over Na₂SO₄. After desolventizing under reduced pressure, it was dried under high vacuum.

[0108] The structural formula of o-aminophenyl ester is: The structural formula of chloroformamidine hydrochloride is:

[0109]

[0110] The structural formula of the guanidinyl ligand prepared by the above method is as follows:

[0111]

[0112] The NMR data for the above guanidine ligands are as follows:

[0113] 1H NMR (400MHz, CDCl3, 25℃):

[0114] δ=7.71(d,3J(H,H)=7.7Hz,1H;CH),7.33(t,3J(H,H)=8.1Hz,1H;

[0115] CH),6.84(d,3J(H,H)=7.9Hz,1H;CH),6.77(t,3J(H,H)=7.6Hz,

[0116] 1H; CH), 3.92 (s, 1H; CH2), 3.74 (s, 3H; CH3), 2.68 (s, 12H, CH3) ppm.

[0117] Catalyst preparation:

[0118] Take 2 mL of the dried tetrahydrofuran solution (40 °C, 0.5 mmol / mL) of the guanidinium ligand prepared above and add it to 2 mL of dried tetrahydrofuran solution (40 °C, 0.5 mmol / mL) of zinc chloride. Stir the reaction at 40 °C for 30 min, then cool the reaction product to crystallize it, filter it and dry it under vacuum to obtain the catalyst.

[0119] Preparation Example 2

[0120] o-aminophenyl ester (40 mmol), triethylamine (44 mmol), and dried MeCN (65 mL) were mixed thoroughly and added dropwise to a solution of the compound shown in Formula 2 (60 mmol). The mixture was refluxed for 3.5 hours and cooled to room temperature. NaOH aqueous solution (50 mmol in 20 mL H₂O) was added, and the solvent and triethylamine were evaporated under reduced pressure. Guanidine hydrochloride was deprotonated by adding KOH (55 mL, 50 wt%) to obtain the guanidine ligand. The guanidine ligand was extracted three times with 30 mL of MeCN and then dried over Na₂SO₄. After desolventizing under reduced pressure, it was dried under high vacuum.

[0121] The structural formula of the o-aminophenyl ester is: The structural formula of the compound shown in Formula 2 is:

[0122]

[0123] The structural formula of the guanidinyl ligand prepared by the above method is as follows:

[0124]

[0125] Catalyst preparation:

[0126] Take 2 mL of the dry tetrahydrofuran solution (40 °C, 0.5 mmol / mL) of the guanidinium ligand prepared above and add it to 2 mL of dry tetrahydrofuran solution (40 °C, 0.6 mmol / mL) of zinc chloride. Stir the reaction at 40 °C for 30 min, then cool the reaction product to crystallize it, filter it and dry it under vacuum to obtain the catalyst.

[0127] Preparation Example 3

[0128] Take 2 mL of a dry tetrahydrofuran solution (0.5 mmol / mL) of the guanidinium ligand prepared above (guanidinium ligand of Preparation Example 1) and add it to 2 mL of a dry tetrahydrofuran solution (0.7 mmol / mL) of magnesium chloride. Stir the reaction at 30 °C for 60 min, then cool the reaction product to crystallize it, filter it and dry it under vacuum to obtain the catalyst.

[0129] Preparation Example 4

[0130] Take 2 mL of a dry dichloromethane solution (0.5 mmol / mL) of the guanidinium ligand prepared above (guanidinium ligand of Preparation Example 1) and add it to 2 mL of a dry dichloromethane solution (0.65 mmol / mL) of calcium chloride. Stir the reaction at 20 °C for 1.5 h, then cool the reaction product to crystallize, filter and vacuum dry to obtain the catalyst.

[0131] Example 1

[0132] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 100 ppm, the catalyst prepared in Preparation Example 1, and lauryl alcohol as the initiator. The amount of glycolide added was 1 kg, the catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 90℃, and the reaction time was 2 h. After the pre-reaction, the material was transferred to a static reactor for subsequent reaction at 150℃ for 5 h. Finally, the material was subjected to devolatilization treatment at 220℃ for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.2 dL / g, a glycolide content of 1.1 wt%, and a weight-average molecular weight of 148,000.

[0133] Example 2

[0134] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 50 ppm, the catalyst prepared in Example 1, and the initiator. The amount of glycolide added was 1 kg, the catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 90℃, and the reaction time was 2 h. After the pre-reaction, the material was transferred to a static reactor for subsequent reaction at 170℃ for 3 h. Finally, the material was subjected to devolatilization treatment at 220℃ for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.25 dL / g, a glycolide content of 1.1 wt%, and a weight-average molecular weight of 152,000.

[0135] Example 3

[0136] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 50 ppm, the catalyst prepared in Example 1, and the initiator. The amount of glycolide added was 1 kg, the catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 90 °C, and the reaction time was 2 h. After the pre-reaction, the material was transferred to a static reactor for subsequent reaction at 200 °C for 1.5 h. Finally, the material was subjected to devolatilization treatment at 220 °C for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.3 dL / g, a glycolide content of 1.1 wt%, and a weight-average molecular weight of 156,000.

[0137] Example 4

[0138] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 50 ppm, the catalyst prepared in Example 1, and the initiator. The amount of glycolide added was 1 kg. The catalyst content in the reaction system was 300 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 90℃, and the reaction time was 2 h. After the pre-reaction, the material was transferred to a static reactor for the subsequent reaction at 170℃ for 1.5 h. Finally, the material was subjected to devolatilization treatment at 220℃ for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.3 dL / g, a glycolide content of 1.2 wt%, and a weight-average molecular weight of 155,000.

[0139] Example 5

[0140] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 50 ppm, the catalyst prepared in Example 1, and the initiator. The amount of glycolide added was 1 kg. The catalyst content and the initiator lauryl alcohol content in the reaction system were both 500 ppm. The pre-reaction temperature was 90 °C, and the reaction time was 2 h. After the pre-reaction, the material was transferred to a static reactor for the subsequent reaction at 170 °C for 1 h. Finally, the material was subjected to devolatilization treatment at 220 °C for 2 min under a vacuum of 200 Pa. The resulting polyglycolic acid resin had an intrinsic viscosity of 1.45 dL / g, a glycolide content of 1.0 wt%, and a weight-average molecular weight of 164,000.

[0141] Example 6

[0142] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 50 ppm, the catalyst prepared in Example 1, and the initiator. The amount of glycolide added was 1 kg. The catalyst content in the reaction system was 800 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 90℃, and the reaction time was 2 h. After the pre-reaction, the material was transferred to a static reactor for the subsequent reaction at 170℃ for 35 min. Finally, the material was subjected to devolatilization treatment at 220℃ for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.52 dL / g, a glycolide content of 1.2 wt%, and a weight-average molecular weight of 171,000.

[0143] Example 7

[0144] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 50 ppm, the catalyst prepared in Example 1, and the initiator. The amount of glycolide added was 1 kg. The catalyst content in the reaction system was 1000 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 90℃, and the reaction time was 2 h. After the pre-reaction, the material was transferred to a static reactor for subsequent reaction at 170℃ for 15 min. Finally, the material was subjected to devolatilization treatment at 220℃ for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.7 dL / g, a glycolide content of 1.7 wt%, and a weight-average molecular weight of 212,000.

[0145] Example 8

[0146] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 100 ppm, the catalyst prepared in Example 1, and the initiator. The amount of glycolide added was 1 kg. The catalyst content in the reaction system was 500 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 100℃, and the time was 1.5 h. After the pre-reaction, the material was transferred to a static reactor for subsequent reaction at 170℃ for 45 min. Finally, the material was subjected to devolatilization treatment at 220℃ for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.57 dL / g, a glycolide content of 0.9 wt%, and a weight-average molecular weight of 175,000.

[0147] Example 9

[0148] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 100 ppm, the catalyst prepared in Example 1, and the initiator. The amount of glycolide added was 1 kg, and the catalyst and initiator were both 500 ppm and 500 ppm respectively. The pre-reaction temperature was 120 °C, and the reaction time was 1 h. After the pre-reaction, the material was transferred to a static reactor for further reaction at 170 °C for 45 min. Finally, the material was subjected to devolatilization treatment at 220 °C for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.68 dL / g, a glycolide content of 0.7 wt%, and a weight-average molecular weight of 208,000.

[0149] Example 10

[0150] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 100 ppm, the catalyst prepared in Example 1, and the initiator. The amount of glycolide added was 1 kg, the catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 120 °C, and the reaction time was 1 h. After the pre-reaction, the material was transferred to a static reactor for subsequent reaction at 200 °C for 1 h. Finally, the material was subjected to devolatilization treatment at 220 °C for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.71 dL / g, a glycolide content of 1.1 wt%, and a weight-average molecular weight of 215,000.

[0151] Example 11

[0152] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 100 ppm, the novel guanidine magnesium catalyst described in this invention (prepared in Preparation Example 3), and an initiator. The amount of glycolide added was 1 kg, the catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 120°C, and the reaction time was 1 h. After the pre-reaction, the material was transferred to a static reactor for subsequent reaction at 200°C for 35 min. Finally, the material was subjected to devolatilization treatment at 220°C for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 2.0 dL / g, a glycolide content of 0.7 wt%, and a weight-average molecular weight of 246,000.

[0153] Example 12

[0154] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 100 ppm, the novel guanidine-based calcium catalyst described in this invention (prepared in Preparation Example 4), and an initiator. The amount of glycolide added was 1 kg, the catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 120 °C, and the reaction time was 1 h. After the pre-reaction, the material was transferred to a static reactor for subsequent reaction at 170 °C for 40 min. Finally, the material was subjected to devolatilization treatment at 220 °C for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.8 dL / g, a glycolide content of 0.8 wt%, and a weight-average molecular weight of 237,000.

[0155] Example 13

[0156] A pre-reaction was carried out in a batch reactor using glycolide with an acid value of 2 mol / t and a water content of 100 ppm, the catalyst prepared in Preparation Example 2, and the initiator. The amount of glycolide added was 1 kg, the catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 120 °C, and the reaction time was 1 h. After the pre-reaction, the material was transferred to a static reactor for subsequent reaction at 200 °C for 1 h. Finally, the material was subjected to devolatilization treatment at 220 °C for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.77 dL / g, a glycolide content of 1.1 wt%, and a weight-average molecular weight of 224,000.

[0157] Comparative Example 1

[0158] A pre-reaction was performed in a batch reactor using glycolide (2 mol / t acid value, 100 ppm water content), stannous octoate, and an initiator. The glycolide content was 1 kg, the catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 120℃, and the reaction time was 1 h. After the pre-reaction, the material was transferred to a static reactor for further reaction at 200℃ for 45 min. Finally, the material underwent devolatilization treatment at 220℃ for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 0.7 dL / g, a glycolide content of 1.0 wt%, and a weight-average molecular weight of 110,000.

[0159] Comparative Example 2

[0160] A pre-reaction was performed in a reactor using glycolide (2 mol / t acid value, 100 ppm water content), stannous chloride, and an initiator. The glycolide content was 1 kg, the catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 120℃, and the reaction time was 1 h. After the pre-reaction, the material was transferred to a static reactor for further reaction at 200℃ for 20 min. Finally, the material underwent devolatilization treatment at 220℃ for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.2 dL / g, a glycolide content of 0.9 wt%, and a weight-average molecular weight of 151,000.

[0161] Comparative Example 3

[0162] A pre-reaction was performed in a batch reactor using glycolide (2 mol / t acid value, 100 ppm water content), an existing guanidine zinc catalyst, and an initiator. The amount of glycolide added was 1 kg, the catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 120℃, and the reaction time was 1 h. After the pre-reaction, the material was transferred to a static reactor for subsequent reaction at 200℃ for 40 min. Finally, the material underwent devolatilization treatment at 220℃ for 2 min under a vacuum of 200 Pa, yielding a polyglycolic acid resin with an intrinsic viscosity of 1.12 dL / g, a glycolide content of 1.3 wt%, and a weight-average molecular weight of 143,000.

[0163] The structural formulas of guanidino ligands in existing guanidino zinc catalysts are as follows:

[0164]

[0165] Comparative Example 4

[0166] A pre-reaction was performed in a batch reactor using glycolide (2 mol / t acid value, 100 ppm water content), an existing guanidine zinc catalyst, and an initiator. The amount of glycolide added was 1 kg. The catalyst content was 100 ppm, and the initiator lauryl alcohol content was 500 ppm. The pre-reaction temperature was 120℃, and the reaction time was 1 h. After the pre-reaction, the material was transferred to a static reactor for further reaction at 200℃ for 1 h. Finally, the material underwent devolatilization treatment at 220℃ for 2 min under a vacuum of 200 Pa. The resulting polyglycolic acid resin had an intrinsic viscosity of 1.19 dL / g, a glycolide content of 0.7 wt%, and a weight-average molecular weight of 147,000.

[0167] The structural formulas of guanidino ligands in existing guanidino zinc catalysts are as follows:

[0168]

[0169] In the comparative example set by the present invention, the optimal reaction time is the time for transferring the material to the static reactor for post-reaction after the pre-reaction is completed. If the post-reaction time is extended, it will lead to the degradation of the product and make the reaction result worse.

[0170] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A guanidine ligand having the following structural formula: in, R1 is located at the ortho, meta, or para position of the guanidinium group attached to the benzene ring; R1 is selected from -(CH2)m-COOR4, m is selected from 0, and R4 is selected from C1-C10 alkyl groups; R2 and R3 are each independently selected from C1-C20 straight-chain alkyl groups; The value of n is any integer from 1 to 2; Alternatively, the guanidinium ligand is .

2. The guanidine ligand according to claim 1, characterized in that: R4 is selected from C1-C5 alkyl groups.

3. The guanidine ligand according to claim 2, characterized in that: R4 is selected from C1-C3 straight-chain alkyl groups.

4. The guanidine ligand according to claim 3, characterized in that: R4 is selected from methyl.

5. The guanidine ligand according to claim 1, characterized in that: R2 and R3 are each independently selected from C1-C10 straight-chain alkyl groups.

6. The guanidine ligand according to claim 5, characterized in that: R2 and R3 are each independently selected from C1-C5 straight-chain alkyl groups.

7. The guanidinyl ligand according to claim 6, characterized in that: R2 and R3 are each independently selected from C1-C3 straight-chain alkyl groups.

8. The guanidine ligand according to claim 7, characterized in that: R2 and R3 are each independently selected from -CH3 and -CH2-CH3.

9. A method for preparing a guanidine ligand according to any one of claims 1-8, comprising the following steps: The guanidinyl ligand is prepared by mixing the compound shown in Formula 1, an organic base, and solvent A, and then adding the compound shown in Formula 2 to react. The compound represented by Formula 1 has the following general structural formula: ； The compound shown in Formula 2 has the following general structural formula: 。 10. The method for preparing the guanidinium ligand according to claim 9, characterized in that: The organic base is selected from organic amines; Solvent A is selected from nitrile solvents; The reaction includes a post-processing step.

11. The method for preparing the guanidinium ligand according to claim 10, characterized in that: The organic base is selected from triethylamine; Solvent A is MeCN; The post-processing steps involve adding an inorganic alkali solution to the reaction product, followed by vacuum distillation, then adding another inorganic alkali solution, extraction, and drying.

12. The method for preparing the guanidinium ligand according to claim 11, characterized in that: The inorganic base in the inorganic base solution is selected from at least one of NaOH and KOH.

13. The method for preparing the guanidinium ligand according to claim 12, characterized in that: The post-processing involves adding NaOH solution, followed by vacuum distillation, then adding KOH solution, extraction, and drying.

14. The method for preparing the guanidinium ligand according to claim 13, characterized in that: The concentration of the NaOH solution is 1-5 mol / L; The concentration of the KOH solution is 10-20 mol / L.

15. The method for preparing the guanidinium ligand according to claim 9, characterized in that: The molar ratio of the organic base to the compound shown in Formula 1 is (1-10):1; and / or, The concentration of the compound represented by Formula 1 in solvent A is 0.1-1 mol / L; and / or, The volume molar ratio of the compound shown in Formula 2 to the compound shown in Formula 1 is (1-11):1; and / or, The reaction time is 3-10 hours; and / or, The reaction was carried out at room temperature.

16. The method for preparing the guanidinium ligand according to claim 15, characterized in that: The molar ratio of the organic base to the compound shown in Formula 1 is (1-2):1; and / or, The concentration of the compound represented by Formula 1 in solvent A is 0.5-0.7 mol / L; and / or, The volume molar ratio of the compound shown in Formula 2 to the compound shown in Formula 1 is (2-8):

1.

17. A catalyst comprising a complex formed from at least one of the guanidinium ligands of any one of claims 1-8 and a halide of metal M or an oxide of metal M; The metal M is selected from at least one of Group IIA, Group IIB, Group IVA or Group VIII.

18. The catalyst according to claim 17, characterized in that: In the catalyst, the molar ratio of the guanidinyl ligand to metal M is 1:(1-3); and / or, The metal M is selected from at least one of Zn, Mg, Ca, and Fe.

19. The catalyst according to claim 18, characterized in that: In the catalyst, the molar ratio of the guanidinyl ligand to metal M is 1:(1-1.5); and / or, The halide of metal M is selected from at least one of magnesium chloride, zinc chloride, calcium chloride, magnesium bromide, and zinc bromide; and / or, The oxide of metal M is selected from at least one of zinc oxide and magnesium oxide.

20. A method for preparing the catalyst according to any one of claims 17-19, comprising the following steps: The catalyst is obtained by reacting the guanidinium ligand with at least one of the halides of metal M and the oxides of metal M in solvent B, followed by post-treatment.

21. The method for preparing the catalyst according to claim 20, characterized in that: In the reaction system, the molar volume ratio of guanidinyl ligand to solvent B is 1 mmol : (2 mL - 10 mL); and / or, The molar ratio of the guanidinium ligand to the metal M in the halide and / or oxide of metal M is 1:(1-3); and / or, Solvent B is selected from at least one of tetrahydrofuran, dichloromethane, trichloromethane, and acetonitrile; and / or, The reaction temperature is 10-40℃; and / or, The reaction time is 15 min to 2 h; and / or, The post-treatment involved cooling the reaction product, crystallizing it, filtering it, and vacuum drying it to obtain the catalyst.

22. The method for preparing the catalyst according to claim 21, characterized in that: The molar ratio of the guanidinium ligand to the metal M in the halide and / or oxide of metal M is 1:(1-1.5); and / or, Solvent B is selected from tetrahydrofuran and acetonitrile.

23. A method for preparing polyglycolic acid resin, comprising the following steps: Under the catalysis of the catalyst according to any one of claims 17-19 or the catalyst prepared by any one of claims 20-22, glycolide and initiator are reacted to generate polyglycolic acid resin.

24. The method for preparing polyglycolic acid resin according to claim 23, comprising the following steps: (1) Pre-reacting glycolide, catalyst and initiator; (2) After the pre-reaction is completed, a post-reaction and post-treatment are carried out to obtain polyglycolic acid resin.

25. The method for preparing polyglycolic acid resin according to claim 24, characterized in that: The acid value of the glycolide is 2-100 mol / t, and the water content is 50-1000 ppm; and / or, The initiator is selected from at least one of lauryl alcohol, decyl alcohol, decanediol, and undecyl alcohol.

26. The method for preparing polyglycolic acid resin according to claim 24, characterized in that: In the reaction system, The catalyst content is 100ppm-1000ppm; and / or, The initiator content is 50-2000 ppm.

27. The method for preparing polyglycolic acid resin according to claim 26, characterized in that: In the reaction system, The catalyst content is 100ppm-500ppm; and / or, The initiator content is 300-500 ppm.

28. The method for preparing polyglycolic acid resin according to claim 24, characterized in that: The pre-reaction temperature is 80-130℃; and / or, The pre-reaction time is 1-2 hours; and / or, The temperature of the subsequent reaction is 130-230℃; and / or, The post-reaction time is 15 min-5 h; and / or, The post-processing includes devolatilization.

29. The method for preparing polyglycolic acid resin according to claim 28, characterized in that: The temperature of the pre-reaction is 90-120℃; and / or, The pre-reaction time is 1 hour to 1.5 hours; and / or, The temperature of the subsequent reaction is 190-220℃; and / or, The post-reaction time is 15 min to 1 h; and / or, The temperature of the devolatilization treatment is 200-230℃; and / or, The devolatilization treatment time is 1 min to 1 h; and / or, The vacuum degree of the devolatilization process is 100Pa-50kPa.

30. The method for preparing polyglycolic acid resin according to claim 29, characterized in that: The temperature of the devolatilization treatment is 210-220℃; and / or, The devolatilization treatment time is 10 min-30 min; and / or, The vacuum degree of the devolatilization process is 100Pa-200Pa.

31. The method for preparing polyglycolic acid resin according to claim 23, characterized in that: The polyglycolic acid resin contains less than 3 wt% glycolide; and / or The polyglycolic acid resin has a molecular weight of 148,000-246,000; and / or, The intrinsic viscosity of the polyglycolic acid resin is 1.2-2.0 dL / g.

32. The method for preparing polyglycolic acid resin according to claim 23, characterized in that: The polyglycolic acid resin contains less than 1.2 wt% glycolide; and / or, The intrinsic viscosity of the polyglycolic acid resin is 1.6-1.8 dL / g.

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