A bifunctional metal-organic framework material and a preparation method for catalytically preparing high molecular weight polybutylene succinate

Abstract

The present invention provides a bifunctional metal-organic framework material and a preparation method for catalytically preparing high-molecular-weight polybutylene succinate. The bifunctional metal-organic framework material is prepared by the following steps: adding a zirconium salt, an organic ligand and a chelating agent into an organic solvent, heating to 120-150 °C for a self-assembly reaction to obtain a metal-organic framework Zr-MOF; reacting the metal-organic framework Zr-MOF with a bio-organic guanidine at 50-90 °C, and adding a tin salt for coordination to obtain Sn 2+ coordinated Zr-MOF, thereby obtaining the bifunctional metal-organic framework material. The high-molecular-weight polybutylene succinate is prepared using the above bifunctional metal-organic framework material as a catalyst. The present invention improves the catalytic efficiency and the polycondensation reaction rate, reduces the terminal carboxyl groups of the product, increases the molecular weight of polybutylene succinate, optimizes the product color and subsequent processing performance, and expands the application range.

Description

Technical Field

[0001] The invention relates to a dual-functional metal organic framework material and a catalytic preparation method thereof of high molecular weight polybutylene succinate and a preparation method thereof, belonging to the technical field of polymer material preparation. Background Art

[0002] Due to the non-degradability of traditional plastics, their products have brought convenience and benefits to people's lives and industrial production, but also brought increasingly serious environmental pollution problems. Degradable plastics are an important way to solve this problem. Polybutylene succinate (PBS), obtained by polymerizing petroleum raw materials succinic acid and butanediol, is a typical biodegradable plastic that can replace traditional plastics and is widely used in various fields of human life, and has been widely developed.

[0003] At present, there are still a series of problems in the synthesis of polybutylene succinate using bio-based succinic acid. Due to the differences in the catalysts used, there are problems such as low catalytic efficiency, long polycondensation time, unstable reaction, and subsequent problems such as low product molecular weight, product degradation and poor color, and substandard mechanical properties.

[0004] High molecular weight polybutylene succinate comprehensive performance is suitable with polypropylene, and in order to prepare high molecular weight polybutylene succinate, scholars have explored a lot of methods.As DAE KYUNG SONG (DAE KYUNG SONG, YONG KIELSUNG, Journal of Applied Polymer Science, 1995Vol.56,1381-1395), adopting solution polymerization to react and prepared the polybutylene succinate that number-average molecular weight is 16000 in 20 hours, but the molecular weight of this product is still not high.For another example, patent CN1424339A discloses and adopts succinic acid and butanediol at 160 ℃ of normal pressure esterification 3-4 hour, then adds organotin and cadmium acetate step by step as catalyst under high temperature high vacuum condition, prepared the synthesis technique of polybutylene succinate that weight-average molecular weight is 137000, molecular weight distribution is 1.9 in 9 hours. Although this process can produce high molecular weight polybutylene succinate, the process is relatively complicated, requiring the catalyst to be added in batches, the reaction time is also long, and the cost is high.

[0005] Another effective method to increase molecular weight is the chain extension method. Showa Polymer Materials Co., Ltd. of Japan has been relatively successful in preparing high molecular weight polybutylene succinate by chain extension. The company uses polybutylene succinate with a number average molecular weight of at least 10,000 as a prepolymer and diisocyanate as a chain extender to prepare high molecular weight polybutylene succinate by melt reaction. The specific preparation process disclosed in its patents (US5391644, US5348700, US5525409) is as follows: First, 1,4-butanediol and butanediol are esterified at 190-210°C and normal pressure for 3.5 hours, then polycondensed at 190-210°C and 2-20 mmHg vacuum for 3.5 hours, and then a catalyst is added to the reaction system. , the temperature is raised to 215-220°C, and the reaction is continued for 5.5 hours under a vacuum condition of 15-0.2 mmHg to obtain a butylene succinate prepolymer with a number average molecular weight of 16,800 and a weight average molecular weight of 43,600. The prepolymer is then reacted with diisocyanate at 180-200°C for 1 hour to obtain a polybutylene succinate product with a number average molecular weight of 35,500 and a weight average molecular weight of 170,000. However, due to the wide molecular weight distribution (4.8) of the product, its strength is limited, and its production cycle is long and the cost is high, which greatly limits its application range.

[0006] The catalysts reported in the literature on the synthesis of PBS are mostly heavy metal catalysts such as stannous octoate, stannous chloride, dibutyltin oxide, antimony alkoxides, etc. (CN103724599A, CN102019202A). Such metal catalysts have certain cytotoxicity, so the degradation of the materials will cause certain pollution to the environment. On the other hand, the weight average molecular weight (Mw) of PBS products synthesized by the direct method (using butanediol and succinic acid as raw materials) reported in the literature so far is 1.4×10 5 Below, and Mw≥1.4×10 5 PBS products are all synthesized by medium molecular weight PBS chain extension method, and the chain extender (such as isocyanate) used has certain toxicity (Wang Yanliang et al., New Chemical Materials, 2011, 12, 43-45). 5 PBS has important uses in high-performance biodegradable plastic products.

[0007] CN201510173741.4 Based on the long-term research on the use of bio-organic guanidine to synthesize environmentally friendly and biodegradable materials, we have recently successfully developed a non-toxic bio-organic guanidine catalyst to synthesize high molecular weight Mw≥1.4×10 5 New process for polybutylene succinate. Summary of the invention

[0008] The main purpose of the present invention is to provide a method for preparing high molecular weight polybutylene succinate which can solve the problems of catalyst toxicity, excessive butanediol and low molecular weight of polybutylene succinate. The method adopts a bifunctional metal organic framework material as a catalyst to prepare high molecular weight polybutylene succinate.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0010] To achieve the above object, the present invention first provides a dual-functional metal organic framework material, specifically, the preparation method thereof is:

[0011] (1) adding a zirconium salt, an organic ligand and a chelating agent to a first organic solvent, uniformly dispersing the mixture by ultrasonication, and then heating the mixture to 120-150° C. for a self-assembly reaction for 24-30 hours to obtain a self-assembled product; filtering the residue, washing it, and drying it to obtain a metal organic framework Zr-MOF;

[0012] (2) adding the metal organic framework Zr-MOF and the bio-organic guanidine to a second organic solvent, mixing them evenly, reacting them at 50-90° C. for 6-12 hours, and then adding tin salt to coordinate them by impregnation to obtain Sn 2+ Coordinated Zr-MOF, i.e. the bifunctional metal-organic framework material.

[0013] According to a specific embodiment of the present invention, preferably, the zirconium salt is one or a combination of two or more of zirconium phosphate, zirconium chloride, zirconium sulfate, and zirconium n-propoxide.

[0014] According to a specific embodiment of the present invention, preferably, the ratio of the zirconium salt, the organic ligand and the chelating agent is 1:2-4:1-4.

[0015] According to a specific embodiment of the present invention, preferably, the organic ligand is one or a combination of two or more of 2-aminoterephthalic acid, terphenyl dicarboxylic acid, 2-sulfonate terephthalic acid, benzene-1,3,5-tricarboxylic acid and 2',3'-diamino[1,1':4',1'-terphenyl]-4,4'-dicarboxylic acid.

[0016] According to a specific embodiment of the present invention, preferably, the chelating agent is at least one of citric acid, tartaric acid, itaconic acid and sebacic acid.

[0017] According to a specific embodiment of the present invention, preferably, the first organic solvent is N,N-dimethylformamide, methanol or anhydrous ethanol;

[0018] The second organic solvent is N,N-dimethylformamide, methanol or anhydrous ethanol;

[0019] Preferably, the first organic solvent and the second organic solvent are the same solvent.

[0020] According to a specific embodiment of the present invention, preferably, the bio-organic guanidine is one or a combination of two or more of guanidinoacetic acid, arginine and creatine.

[0021] According to a specific embodiment of the present invention, preferably, the molar ratio of the Zr-MOF to the bio-organic guanidine is 1:0.4-0.7.

[0022] According to a specific embodiment of the present invention, preferably, the molar ratio of the tin salt to the Zr-MOF is 1:0.5-1.

[0023] According to a specific embodiment of the present invention, preferably, the tin salt is one or a combination of two or more of triphenyltin chloride, stannous sulfate and stannous chloride.

[0024] According to a specific embodiment of the present invention, preferably, the concentration of the zirconium salt in the organic solvent is 0.2-0.4 mol / L.

[0025] According to a specific embodiment of the present invention, preferably, the concentration of the bio-organic guanidine in the second organic solvent is 0.05-0.2 mol / L.

[0026] According to a specific embodiment of the present invention, preferably, the bifunctional metal organic framework material is a catalyst with two active centers based on the metal organic framework material structure, namely, bio-organic guanidine, Sn 2+ For the active center.

[0027] On this basis, the present invention provides a method for preparing high molecular weight polybutylene succinate. Specifically, the preparation method comprises:

[0028] Bio-based succinic acid and / or succinic anhydride are subjected to an esterification reaction with 1,4-butanediol to prepare oligomeric butylene succinate, and then a bifunctional metal organic framework material is added to carry out further esterification polymerization and polycondensation to prepare high molecular weight polybutylene succinate.

[0029] According to a specific embodiment of the present invention, preferably, the preparation method comprises the following steps: mixing bio-based succinic acid and / or succinic anhydride and 1,4-butanediol in a molar ratio of 1:1.1-1.5, carrying out a constant temperature and normal pressure esterification reaction at 130-160°C for 2-3 hours, then heating up and adding a bifunctional metal organic framework material, and when the temperature rises to 200-230°C, carrying out negative compression polymerization (the vacuum degree is preferably 20-60Pa), and the reaction time is 2-4 hours to obtain a high molecular weight polybutylene succinate.

[0030] According to a specific embodiment of the present invention, preferably, the amount of the bifunctional metal organic framework material is equivalent to 0.01%-0.5% of the amount of 1,4-butanediol.

[0031] Another aspect of the present invention provides a high molecular weight polybutylene succinate, which is prepared by the above method.

[0032] According to a specific embodiment of the present invention, preferably, the molecular weight of the high molecular weight polybutylene succinate is ≥180,000, preferably 180,000-220,000, and more preferably 190,000-210,000.

[0033] According to a specific embodiment of the present invention, preferably, the molecular weight distribution of the high molecular weight polybutylene succinate is 1.3-1.6.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) The present invention adopts a bifunctional metal organic framework material as a bifunctional catalyst, which reduces the addition of other components, such as catalyst stabilizers, co-catalysts, and chain extenders, thereby avoiding product complexity; at the same time, the catalyst can achieve bifunctional catalysis of esterification catalysis and polycondensation catalysis, and is non-toxic and non-polluting.

[0036] (2) The polybutylene succinate obtained by the preparation method of the present invention has a relatively high molecular weight and a relatively concentrated molecular weight distribution. In addition, no excessive amount of butanediol or chain extender is required. DETAILED DESCRIPTION

[0037] The embodiments of the technical solution of the present invention are described in detail below. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present invention. Those skilled in the art can change, modify, replace and modify the above embodiments within the scope of the present invention.

[0038] The experimental methods in the following examples are all conventional methods unless otherwise specified.

[0039] Unless otherwise specified, the test materials used in the following examples were purchased from conventional reagent stores.

[0040] The quantitative tests in the following examples were all performed three times, and the data are the average values ​​or the average values ​​± standard deviations of the three repeated experiments.

[0041] The following is a description of the specific implementation methods:

[0042] Example 1

[0043] This embodiment provides a method for preparing high molecular weight polybutylene succinate, which comprises:

[0044] 1) adding zirconium phosphate, 2-aminoterephthalic acid and citric acid in a molar ratio of 1:2:1 to N,N-dimethylformamide, and uniformly dispersing by ultrasonication to make the concentration of zirconium phosphate reach 0.2 mol / L, and then heating to 120° C. to carry out self-assembly reaction for 24 hours to obtain a self-assembled product; filtering the residue, washing, and drying to obtain a metal organic framework Zr-MOF.

[0045] 2) The metal organic framework Zr-MOF and guanidine acetic acid in step 1) are added to ethanol at a molar ratio of 1:0.5, wherein the concentration of guanidine acetic acid in ethanol is 0.1 mol / L, mixed evenly, reacted at 60° C. for 12 h, and then tin salt (the molar ratio of tin salt to Zr-MOF is 1:1) is added, and coordination is performed by impregnation to obtain Sn 2+ Coordinated Zr-MOF, i.e. the bifunctional metal-organic framework material.

[0046] 3) placing bio-based succinic acid or succinic anhydride and 1,4-butanediol in a molar ratio of 1:1.1 in a reaction vessel, stirring and heating to 130° C., first conducting a constant temperature and normal pressure esterification reaction for 2 hours, then heating again and adding the bifunctional metal organic framework material in step 2) (the added amount accounts for 0.01% of the amount of 1,4-butanediol), and when the temperature rises to 200° C., conducting negative compression polymerization (vacuum degree is 20 Pa), and the reaction time is 2 hours to obtain polybutylene succinate, which is extruded and granulated or directly made into products.

[0047] 4) Forming the obtained polybutylene succinate into a film: first drying the obtained polybutylene succinate in a vacuum oven for 8 hours, then taking PBS and placing it in a German large-scale analytical instrument HAAKE Rheocord9000 rheometer (Rheocord90HAAKE Rheometer, Mess-Technic GmbH, Germany) for melting: setting the temperature to 150° C. and the rotation speed to 50 rpm; taking out all the molten material and pressing it into a thin sheet on a flat plate vulcanizer, the sheeting conditions are: preheating for 10 minutes, pre-pressing at about 5 MPa for 1 minute, then increasing the pressure to 15 MPa for hot pressing for 3 minutes, and then cold pressing for 15 minutes; then cutting the sheet into ISO standard size and performing performance testing.

[0048] The molecular weight of the product is 1.89×10 5 The molecular weight distribution detected by GPC is 1.46. The tensile strength of the film prepared from the product is 56.84 MPa and the elongation at break is 421%.

[0049] Example 2

[0050] This embodiment provides a method for preparing high molecular weight polybutylene succinate, which comprises:

[0051] 1) adding zirconium phosphate, 2-aminoterephthalic acid and citric acid in a molar ratio of 1:2:1 to N,N-dimethylformamide, and uniformly dispersing by ultrasonication to make the concentration of zirconium phosphate reach 0.2 mol / L, and then heating to 120° C. to carry out self-assembly reaction for 24 hours to obtain a self-assembled product; filtering the residue, washing, and drying to obtain a metal organic framework Zr-MOF.

[0052] 2) The metal organic framework Zr-MOF and guanidine acetic acid in step 1) are added to ethanol at a molar ratio of 1:0.5, the concentration of guanidine acetic acid in ethanol is 0.1 mol / L, mixed evenly, reacted at 60° C. for 12 h, and then tin salt (the molar ratio of tin salt to Zr-MOF is 1:0.8) is added, and coordination is carried out by impregnation method to obtain Sn 2+ Coordinated Zr-MOF, i.e. the bifunctional metal-organic framework material.

[0053] 3) placing bio-based succinic acid or succinic anhydride and 1,4-butanediol in a molar ratio of 1:1.5 in a reaction vessel, stirring and heating to 160° C., first conducting a constant temperature and normal pressure esterification reaction for 3 hours, then heating again and adding the bifunctional metal organic framework material in step 2) (the added amount accounts for 0.5% of the amount of 1,4-butanediol), and when the temperature rises to 230° C., conducting negative compression polymerization (vacuum degree is 60 Pa), and the reaction time is 4 hours to obtain polybutylene succinate, which is extruded and granulated or directly made into products.

[0054] 4) Forming the obtained polybutylene succinate into a film: first drying the obtained polybutylene succinate in a vacuum oven for 8 hours, then taking PBS and placing it in a German large-scale analytical instrument HAAKE Rheocord9000 rheometer (Rheocord90HAAKE Rheometer, Mess-Technic GmbH, Germany) for melting: setting the temperature to 150° C. and the rotation speed to 50 rpm; taking out all the molten material and pressing it into a thin sheet on a flat plate vulcanizer, the sheeting conditions are: preheating for 10 minutes, pre-pressing at about 5 MPa for 1 minute, then increasing the pressure to 15 MPa for hot pressing for 3 minutes, and then cold pressing for 15 minutes; then cutting the sheet into ISO standard size and performing performance testing.

[0055] The molecular weight of the product is 1.96×10 5 The molecular weight distribution detected by GPC is 1.43. The tensile strength of the film prepared from the product is 57.29 MPa and the elongation at break is 447%.

[0056] Example 3

[0057] This embodiment provides a method for preparing high molecular weight polybutylene succinate, which comprises:

[0058] 1) adding zirconium phosphate, 2-aminoterephthalic acid and citric acid in a molar ratio of 1:2:1 to N,N-dimethylformamide, and uniformly dispersing by ultrasonication to make the concentration of zirconium phosphate reach 0.2 mol / L, and then heating to 120° C. to carry out self-assembly reaction for 24 hours to obtain a self-assembled product; filtering the residue, washing, and drying to obtain a metal organic framework Zr-MOF.

[0059] 2) The metal organic framework Zr-MOF and guanidine acetic acid in step 1) are added to ethanol at a molar ratio of 1:0.5, the concentration of guanidine acetic acid in ethanol is 0.1 mol / L, mixed evenly, reacted at 60° C. for 12 h, and then tin salt (the molar ratio of tin salt to Zr-MOF is 1:0.6) is added, and coordination is carried out by impregnation method to obtain Sn 2+ Coordinated Zr-MOF, i.e. the bifunctional metal-organic framework material.

[0060] 3) placing bio-based succinic acid or succinic anhydride and 1,4-butanediol in a molar ratio of 1:1.35 in a reaction vessel, stirring and heating to 150° C., first conducting a constant temperature and normal pressure esterification reaction for 3 hours, then heating again and adding the bifunctional metal organic framework material in step 2) (the added amount accounts for 0.3% of the amount of 1,4-butanediol), and when the temperature rises to 220° C., conducting negative compression polymerization (vacuum degree is 20 Pa), and the reaction time is 2.5 hours to obtain polybutylene succinate, which is extruded and granulated or directly made into products.

[0061] 4) Forming the obtained polybutylene succinate into a film: first drying the obtained polybutylene succinate in a vacuum oven for 8 hours, then taking PBS and placing it in a German large-scale analytical instrument HAAKE Rheocord9000 rheometer (Rheocord90HAAKE Rheometer, Mess-Technic GmbH, Germany) for melting: setting the temperature to 150° C. and the rotation speed to 50 rpm; taking out all the molten material and pressing it into a thin sheet on a flat plate vulcanizer, the sheeting conditions are: preheating for 10 minutes, pre-pressing at about 5 MPa for 1 minute, then increasing the pressure to 15 MPa for hot pressing for 3 minutes, and then cold pressing for 15 minutes; then cutting the sheet into ISO standard size and performing performance testing.

[0062] The molecular weight of the product is 2.07×10 5 The molecular weight distribution detected by GPC is 1.37. The tensile strength of the film prepared from the product is 57.31 MPa and the elongation at break is 478%.

[0063] Example 4

[0064] This embodiment provides a method for preparing high molecular weight polybutylene succinate, which comprises:

[0065] 1) adding zirconium phosphate, 2-aminoterephthalic acid and citric acid in a molar ratio of 1:2:1 to N,N-dimethylformamide, and uniformly dispersing by ultrasonication to make the concentration of zirconium phosphate reach 0.2 mol / L, and then heating to 120° C. to carry out self-assembly reaction for 24 hours to obtain a self-assembled product; filtering the residue, washing, and drying to obtain a metal organic framework Zr-MOF.

[0066] 2) The metal organic framework Zr-MOF and guanidine acetic acid in step 1) are added to ethanol at a molar ratio of 1:0.5, the concentration of guanidine acetic acid in ethanol is 0.1 mol / L, mixed evenly, reacted at 60° C. for 12 h, and then tin salt is added in an amount (the molar ratio of tin salt to Zr-MOF is 1:0.5), and coordinated by impregnation method to obtain Sn 2+ Coordinated Zr-MOF, i.e. the bifunctional metal-organic framework material.

[0067] 3) placing bio-based succinic acid or succinic anhydride and 1,4-butanediol in a molar ratio of 1:1.35 in a reaction vessel, stirring and heating to 150° C., first conducting a constant temperature and normal pressure esterification reaction for 2.5 hours, then heating again and adding the bifunctional metal organic framework material of step 2) (the added amount accounts for 0.25% of the amount of 1,4-butanediol), and when the temperature rises to 220° C., conducting negative compression polymerization (vacuum degree is 20 Pa), and the reaction time is 3 hours to obtain polybutylene succinate, which is extruded and granulated or directly made into products.

[0068] 4) Forming the obtained polybutylene succinate into a film: first drying the obtained polybutylene succinate in a vacuum oven for 8 hours, then taking PBS and placing it in a German large-scale analytical instrument HAAKE Rheocord9000 rheometer (Rheocord90HAAKE Rheometer, Mess-Technic GmbH, Germany) for melting: setting the temperature to 150° C. and the rotation speed to 50 rpm; taking out all the molten material and pressing it into a thin sheet on a flat plate vulcanizer, the sheeting conditions are: preheating for 10 minutes, pre-pressing at about 5 MPa for 1 minute, then increasing the pressure to 15 MPa for hot pressing for 3 minutes, and then cold pressing for 15 minutes; then cutting the sheet into ISO standard size and performing performance testing.

[0069] The molecular weight of the product is 2.11×10 5The molecular weight distribution detected by GPC is 1.37. The tensile strength of the film prepared from the product is 58.72 MPa and the elongation at break is 459%.

[0070] Comparative Example

[0071] This comparative example provides a conventional preparation method of high molecular weight polybutylene succinate.

[0072] Bio-based succinic acid or succinic anhydride and 1,4-butanediol are placed in a reaction container at a molar ratio of 1:1.1, stirred and heated to 130°C, and firstly subjected to a constant temperature and normal pressure esterification reaction for 2 hours, and then heated again and added with a bio-organic guanidine catalyst, namely guanidinoacetic acid (the added amount accounts for 0.01% of the amount of 1,4-butanediol), and when the temperature rises to 200°C, negative compression polymerization (vacuum degree is 20Pa) is carried out, and the reaction time is 2 hours to obtain polybutylene succinate, which is extruded into granules or directly made into products.

[0073] The obtained polybutylene succinate was made into a film: the obtained polybutylene succinate was first dried in a vacuum oven for 8 hours, and then PBS was taken and placed in a German large-scale analytical instrument HAAKE Rheocord9000 rheometer (Rheocord90HAAKE Rheometer, Mess-Technic GmbH, Germany) for melting: the temperature was set to 150°C and the rotation speed was 50 rpm; all the molten material was taken out and pressed into a thin sheet on a flat vulcanizer, and the sheeting conditions were: preheating for 10 minutes, pre-pressing at about 5 MPa for 1 minute, then increasing the pressure to 15 MPa for hot pressing for 3 minutes, and then cold pressing for 15 minutes; then the sheet was cut into ISO standard size and performance tested.

[0074] The molecular weight of the product is 1.0×10 5 The molecular weight distribution detected by GPC is 1.53. The tensile strength of the film prepared from the product is 51.94 MPa, and the elongation at break is 376%.

[0075] The amounts of 1,4-butanediol and catalyst used in Examples 1-4 and Comparative Examples and the molecular weight, molecular weight distribution, tensile strength and elongation at break of the obtained products are summarized in Table 1:

[0076] Table 1

[0077] Example 1 Example 2 Example 3 Example 4 Comparative Example 1,4-Butanediol / Succinic Acid 1.1 1.5 1.35 1.35 1.1 Catalyst dosage 0.01％ 0.5％ 0.3％ 0.25％ 0.01％ Molecular weight <![CDATA[1.89×10 5 ]]> <![CDATA[1.96×10 5 ]]> <![CDATA[2.07×10 5 ]]> <![CDATA[2.11×10 5 ]]> <![CDATA[1.0×10 5 ]]> Molecular weight distribution 1.46 1.43 1.37 1.37 1.53 Tensile Strength 56.84MPa 57.29MPa 57.31MPa 58.72MPa 51.94MPa Elongation at break 421％ 447％ 478％ 459％ 376％

[0078] Under the conditions provided by the present invention, the amount of butanediol used is 1.1-1.5 times the molar amount of succinic acid, and the amount is reduced; only one catalyst is used in the reaction, which reduces the addition of other components, avoids the problem of catalyst toxicity, and the reaction system is simple; the molecular weight of polybutylene succinate is 1.89×10 5The molecular weight is significantly increased and no chain extender is required; the molecular weight distribution is below 1.46 and is relatively concentrated.

[0079] It can be seen from Table 1 that under the conditions provided by the present invention, the catalytic effect of the bifunctional metal organic framework material is significantly better than that of the monofunctional catalyst, and the bifunctional catalyst has both prepolymerization and polycondensation functions, and can obtain polybutylene succinate with a higher molecular weight. The molecular weight is significantly increased without the help of a chain extender, and the molecular weight distribution is relatively concentrated, and the mechanical properties are excellent.

Claims

1. A bifunctional metal-organic framework material, and its preparation method is as follows: (1) Add zirconium salt, organic ligand and chelating agent into the first organic solvent, ultrasonically disperse evenly, then heat up to 120 - 150 °C for self-assembly reaction for 24 - 30 h to obtain the self-assembled product; filter to obtain the filter residue, wash and dry to obtain the metal-organic framework Zr-MOF; (2) Add the metal-organic framework Zr-MOF and bio-organic guanidine into a second organic solvent, mix evenly, react at 50-90 °C for 6-12 h, then add a tin salt, and perform coordination by an impregnation method to obtain Sn 2+ coordinated Zr-MOF, namely the bifunctional metal-organic framework material.

2. The bifunctional metal-organic framework material according to claim 1, wherein, the zirconium salt is one or a combination of two or more of zirconium phosphate, zirconium chloride, zirconium sulfate, zirconium propoxide.

3. The bifunctional metal-organic framework material according to claim 1, wherein, the ratio of the zirconium salt, organic ligand and chelating agent is 1:2 - 4:1 - 4.

4. The bifunctional metal-organic framework material according to claim 1, wherein, the organic ligand is one or a combination of two or more of 2-aminoterephthalic acid, terphenyl dicarboxylic acid, 2-sulfoterephthalic acid, benzene-1,3,5-tricarboxylic acid, and 2',3'-diamino(1,1':4',1’-terphenyl)-4,4’-dicarboxylic acid.

5. The bifunctional metal-organic framework material according to claim 1, wherein, the chelating agent is at least one of citric acid, tartaric acid, itaconic acid and sebacic acid.

6. The bifunctional metal-organic framework material according to claim 1, wherein, the first organic solvent is N,N-dimethylformamide, methanol or absolute ethanol; the second organic solvent is N,N-dimethylformamide, methanol or absolute ethanol.

7. The bifunctional metal-organic framework material according to claim 6, wherein, the first organic solvent and the second organic solvent are the same solvent.

8. The bifunctional metal-organic framework material according to claim 1, wherein, the bio-organic guanidine is one or a combination of two or more of guanidinoacetic acid, arginine, creatine.

9. The bifunctional metal-organic framework material according to claim 1, wherein, the molar ratio of Zr-MOF to bio-organic guanidine is 1:0.4 - 0.

7.

10. The bifunctional metal-organic framework material according to claim 1, wherein, the molar ratio of tin salt to Zr-MOF is 1:0.5 - 1.

11. The bifunctional metal-organic framework material according to claim 1 or 10, wherein, the tin salt is one or a combination of two or more of triphenyltin chloride, stannous sulfate and stannous chloride.

12. The bifunctional metal-organic framework material according to claim 1, wherein, the concentration of the zirconium salt in the first organic solvent is 0.2 - 0.4 mol / L.

13. The bifunctional metal-organic framework material according to claim 1, wherein, the concentration of the bio-organic guanidine in the second organic solvent is 0.05 - 0.2 mol / L.

14. The bifunctional metal-organic framework material according to claim 1, wherein, the bifunctional metal-organic framework material is a catalyst with two active centers based on the structure of the metal-organic framework material.

15. A preparation method for catalytically preparing high molecular weight polybutylene succinate, wherein, The preparation method includes: Performing an esterification reaction on bio-based succinic acid and / or succinic anhydride with 1,4-butanediol to prepare oligo (butylene succinate), and then adding the bifunctional metal-organic framework material described in any one of claims 1-14 for further esterification polymerization and polycondensation to prepare high molecular weight poly (butylene succinate).

16. The preparation method according to claim 15, wherein, the preparation method comprises the following steps: mixing bio-based succinic acid and / or succinic anhydride and 1,4-butanediol at a molar ratio of 1:1.1-1.5, carrying out an isothermal esterification reaction at normal pressure at 130-160 °C for 2-3 hours, then heating up and adding the bifunctional metal-organic framework material, and when the temperature rises to 200-230 °C, carrying out negative pressure polycondensation for 2-4 hours to obtain high molecular weight poly (butylene succinate).

17. The preparation method according to claim 16, wherein, in the negative pressure polycondensation, the vacuum degree is 20-60 Pa.

18. The preparation method according to claim 15, wherein, the dosage of the bifunctional metal-organic framework material is equivalent to 0.01%-0.5% of the amount of substance of 1,4-butanediol.