Carbon dioxide-based polypropylene carbonate elastomer and method of making same
By using a composite catalyst system and copolymerization modification, a carbon dioxide-based polypropylene carbonate elastomer with high elasticity and low water absorption was prepared, which solved the thermal performance and toughness problems of PPC, improved the glass transition temperature and mechanical properties of the material, and made it suitable for a variety of applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU ZHONGKE JINLONG CHEM
- Filing Date
- 2026-05-12
- Publication Date
- 2026-06-09
AI Technical Summary
In the existing technology, carbon dioxide-based polypropylene carbonate (PPC) has problems such as poor thermal properties, low toughness, difficulty in processing and modification, poor stability in long-distance transportation, and high water absorption and decreased mechanical properties after modification.
A composite catalyst system consisting of organic bismuth and triethanolamine was used to copolymerize and modify polypropylene carbonate copolymer to introduce ester bond structure. Combined with the synergistic catalytic effect of zinc-cobalt bimetallic cyanide and imidazole ionic liquid, a carbon dioxide-based polypropylene carbonate elastomer with high elasticity and low water absorption was prepared.
It significantly improves the glass transition temperature and mechanical strength of the material, enhances its hydrolysis resistance, and produces an elastomer with high tensile strength and high elongation at break, suitable for elastic seals, medical elastic materials, and packaging materials.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials technology, specifically relating to a carbon dioxide-based polypropylene carbonate elastomer and its preparation method. Background Technology
[0002] Polypropylene carbonate (PPC), a biodegradable material mainly composed of carbon dioxide and epoxy compounds through copolymerization, has advantages such as high transparency, good water and oxygen barrier properties, and being environmentally friendly and non-toxic. Products synthesized from CO2 can not only achieve low-carbon emission reduction, but also contribute to economic development and energy structure adjustment. It has now become an important technical direction for research in the field of renewable carbon.
[0003] However, pure PPC has significant technical drawbacks: poor thermal properties, low thermal decomposition temperature and glass transition temperature, leading to difficulties in processing and modification, and poor stability during long-distance transportation; poor toughness, low notched impact strength and low elongation at break, making it unsuitable for direct use as an elastomer. To address these issues, existing technologies often modify PPC with isocyanates and chain extenders to produce PPC polyurethane elastomers, aiming to combine the biodegradability of PPC with the high elasticity of polyurethane.
[0004] Chinese invention patent application CN115521448A discloses a method for preparing copolymerized modified polypropylene carbonate copolymer. The method involves adding the reactive monomers propylene oxide, saturated aliphatic anhydrides and / or saturated alicyclic anhydrides, and a catalyst into a high-pressure reactor, then introducing carbon dioxide gas to carry out a ring-opening copolymerization reaction. After the copolymerization reaction, a chain extension reaction is further carried out to obtain the copolymerized modified polypropylene carbonate copolymer. The catalyst is triethylboron and tetra-n-butylammonium chloride. However, its catalytic efficiency is relatively low.
[0005] Chinese invention patent application CN116162222A discloses a polypropylene carbonate particle, its preparation method, and its application. The method involves reacting a polypropylene carbonate polyol with an isocyanate under the action of a chain extender to obtain modified polypropylene carbonate. According to the specification, the polypropylene carbonate polyol used in this method has a molecular weight of about 4000 g / mol, and the molecular chain flexibility is still relatively high, resulting in no significant increase in the glass transition temperature of the product.
[0006] Chinese invention patent application CN103755911A discloses a waterborne polyurethane material with high strength and good hydrolysis resistance, prepared by reacting polypropylene carbonate diol (PPC) as the main raw material with diisocyanate and small molecule hydrophilic chain extender. However, pure waterborne polyurethane still has a high water absorption rate due to the introduction of hydrophilic groups, and the film absorbs water and turns white when soaked, resulting in a decrease in mechanical properties.
[0007] Therefore, developing an environmentally friendly, heavy metal-free, synergistically compatible catalytic system, and matching precise raw material ratios and reaction parameters to prepare a carbon dioxide-based polypropylene carbonate elastomer with high elasticity, low permanent deformation, and low water absorption has become a pressing technical problem to be solved in this field. Summary of the Invention
[0008] To address the shortcomings of existing technologies, this invention provides a carbon dioxide-based polypropylene carbonate elastomer and its preparation method. By synergistic design of a composite catalyst system and precise control of reaction parameters, problems such as poor product performance and heavy metal residues in the catalyst are solved in existing technologies, resulting in a carbon dioxide-based polypropylene carbonate elastomer with excellent overall performance.
[0009] To achieve the above-mentioned objectives of this invention, the specific technical solution adopted by this invention is as follows:
[0010] A carbon dioxide-based polypropylene carbonate elastomer, comprising the following raw materials in parts by weight: The mixture comprises 90-110 parts of copolymerized modified polypropylene carbonate copolymer, 20-30 parts of isocyanate, 5-12 parts of chain extender, and 0.03-0.1 parts of composite catalyst, wherein the composite catalyst is composed of organic bismuth and triethanolamine in a mass ratio of 2-3:1.
[0011] Organobismuth compounds, acting as Lewis acid catalysts, can activate the carbon atoms of isocyanate groups (-NCO), promoting their nucleophilic addition reactions with hydroxyl (-OH) or carboxyl (-COOH) groups. The hydroxyl and nitrogen atoms of triethanolamine can coordinate with organobismuth to form a complex structure, stabilizing the active center; the combination of these two significantly enhances the catalytic activity, enabling the full reaction of -NCO with -OH / -COOH at relatively low concentrations, with a mild and controllable reaction.
[0012] Preferably, the preparation method of the copolymerized modified polypropylene carbonate copolymer includes: Propylene oxide, anhydride monomer, and catalyst A are added to a high-pressure reactor, carbon dioxide is introduced, and a ring-opening copolymerization reaction is carried out to obtain a copolymerized modified polypropylene carbonate copolymer; wherein the mass ratio of propylene oxide, anhydride monomer, and catalyst A is 100:15-30:0.05-0.2.
[0013] More preferably, the anhydride monomer is selected from at least one of saturated aliphatic anhydrides, unsaturated aliphatic anhydrides, or aromatic anhydrides, and the catalyst A is composed of zinc-cobalt bimetallic cyanide (Zn-Co DMC) and imidazole ionic liquid.
[0014] In a further preferred embodiment, the anhydride monomer is selected from at least one of succinic anhydride, maleic anhydride, and phthalic anhydride.
[0015] Preferably, the preparation method of catalyst A includes: (1) Add zinc chloride and potassium cobalt cyanide to a ball mill jar, add tert-butanol, ball mill the reaction, wash, sieve, and dry to obtain Zn-Co DMC; (2) Mix Zn-Co DMC with imidazole ionic liquid, ball mill and compound, sieve and dry to obtain catalyst A.
[0016] More preferably, in step (1), the molar ratio of zinc chloride and potassium cobalt cyanide is 3-8:1, the amount of tert-butanol used is 1%-5% of the mass of zinc salt, the washing uses a mixture of water and tert-butanol with a volume ratio of 1:3-5, and the washing is performed 3-5 times.
[0017] More preferably, the mass ratio of Zn-Co DMC to imidazole ionic liquid in step (2) is 100:1-10, and the imidazole ionic liquid is selected from at least one of 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate.
[0018] More preferably, the ball milling speed in steps (1) and (2) is 200-500 rpm, the ball milling time is 1-5 h, the sieve mesh size is 180-220 mesh, the drying temperature is 70-90℃, and the drying time is 2-4 h.
[0019] Preferably, the pressure of carbon dioxide in the reactor is 2.0-4.0 MPa, the temperature of the ring-opening copolymerization reaction is 60-90℃, the time of the ring-opening copolymerization reaction is 6-12 h, and the reaction solution is further subjected to depressurization and devolatilization treatment after the ring-opening copolymerization reaction.
[0020] Preferably, the preparation method of the composite catalyst includes: mixing organic bismuth with triethanolamine evenly to obtain the catalyst.
[0021] Preferably, the isocyanate is selected from at least one of diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and terephthalic diisocyanate; and the chain extender is selected from at least one of 1,4-butanediol, ethylene glycol, diethylene glycol, and 1,6-hexanediol.
[0022] This invention also relates to a method for preparing the above-mentioned carbon dioxide-based polypropylene carbonate elastomer, comprising the following steps: The copolymerized modified polypropylene carbonate copolymer is mixed with isocyanate, chain extender and composite catalyst, and reacted. The reaction product is then cast, cured and post-cured to obtain the final product.
[0023] Preferably, the reaction temperature is 70-90℃ and the reaction time is 2-4h; the curing temperature is 80-100℃ and the curing time is 6-8h; the post-curing temperature is 70-90℃ and the post-curing time is 22-26h.
[0024] This invention modifies PPC by introducing anhydride monomers into the main chain through copolymerization, thereby introducing ester bonds into the molecular chain. The introduction of ester bonds increases the rigidity of the molecular chain, contributing to a higher glass transition temperature and mechanical strength. Furthermore, the presence of ester bonds enhances intermolecular forces, improving the material's resistance to hydrolysis. In addition, copolymerization modification can adjust the hydroxyl value and molecular weight of PPC, making it more suitable for use as a polyurethane soft segment.
[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses a composite catalyst made of zinc-cobalt bimetallic cyanide and imidazole ionic liquid. The two produce a synergistic catalytic effect. Compared with a single catalyst, it significantly improves the efficiency of the ring-opening copolymerization reaction of CO2 with propylene oxide and acid anhydride monomers, reduces the harshness of the reaction conditions, and improves the molecular weight and structural regularity of the copolymer. The addition of imidazole ionic liquid can also improve the dispersibility of the catalyst, reduce catalyst agglomeration, and further enhance the catalytic effect.
[0026] (2) In this invention, polypropylene carbonate is copolymerized with an anhydride monomer to introduce an ester bond structure, which improves the mechanical properties and water resistance of polypropylene carbonate. Then, it is reacted with polyurethane components to prepare an elastomer. The resulting elastomer has high tensile strength, high elongation at break, and excellent water resistance. It can be widely used in elastic seals, medical elastic materials, packaging materials and other fields. Detailed Implementation
[0027] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are not intended to limit the present invention, but only to illustrate the present invention. Unless otherwise specified, the experimental methods used in the following embodiments are generally performed under conventional conditions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.
[0028] Organic bismuth (BiCAT) ® 8 (M), purchased from Shanghai Kaiyin Chemical Co., Ltd.
[0029] Preparation of catalyst A (Zn-Co DMC / [BMIM]BF4 composite catalyst): (1) Add ZnCl2 (5.0 g) and K3Co(CN)6 (2.5 g) to a ball mill jar, add 1.5 mL of tert-butanol, and add zirconia grinding beads (ball-to-material mass ratio of 10:1). Ball mill in a planetary ball mill at 300 rpm for 3 hours. After ball milling, pass the mixture through a 200-mesh sieve, wash three times with a tert-butanol-water mixture (volume ratio of 1:4), and vacuum dry at 80 °C for 2 hours to obtain Zn-Co DMC.
[0030] (2) Mix the above Zn-Co DMC with [BMIM]BF4 (0.3g) and ball mill for 1 hour as above. After ball milling, pass the mixture through a 200-mesh sieve to separate the catalyst powder from the zirconium oxide ball milling beads. Dry under vacuum at 80°C for 2 hours to obtain the final product.
[0031] Example 1 A method for preparing a carbon dioxide-based polypropylene carbonate elastomer includes the following steps: (1) Under anhydrous and oxygen-free conditions, 100 parts by weight of propylene oxide, 20 parts by weight of succinic anhydride, and 0.1 parts by weight of catalyst A (Zn-Co DMC / [BMIM]BF4 composite catalyst) were added to a high-pressure reactor. After sealing, the air inside the reactor was replaced three times with high-purity CO2. Then, CO2 was introduced until the pressure inside the reactor reached 3.0 MPa. The temperature was raised to 80°C, and the reaction was stirred for 10 hours. After the reaction was completed, the reactor was cooled to room temperature, and the unreacted CO2 was slowly released. Then, vacuum devolatilization was performed (the vacuum system was turned on, the vacuum degree was maintained at -0.09 MPa, and the reactor was stirred and extracted at 60°C for 60 minutes to remove the residual propylene oxide monomer), resulting in a viscous liquid, which is the copolymerized modified polypropylene carbonate copolymer (PPC-PA).
[0032] (2) Take 100 parts by weight of PPC-PA, heat it to 80°C to melt it, then add 22 parts by weight of hexamethylene diisocyanate (HDI), 8 parts by weight of 1,4-butanediol (BDO), and 0.05 parts by weight of a composite catalyst (obtained by mixing organic bismuth and triethanolamine at a mass ratio of 2.5:1). React at 80°C for 3 hours. After the reaction is completed, pour the reactants into a mold preheated to 90°C and cure at 90°C for 8 hours. After demolding, place the elastomer in an 80°C oven for post-curing treatment and let it stand for 24 hours to obtain the final product.
[0033] Example 2 A method for preparing a carbon dioxide-based polypropylene carbonate elastomer includes the following steps: (1) Under anhydrous and oxygen-free conditions, 100 parts by weight of propylene oxide, 15 parts by weight of succinic anhydride, and 0.05 parts by weight of catalyst A (Zn-Co DMC / [BMIM]BF4 composite catalyst) were added to a high-pressure reactor. After sealing, the air inside the reactor was replaced three times with high-purity CO2. Then, CO2 was introduced until the pressure inside the reactor reached 2.0 MPa. The temperature was raised to 70°C, and the reaction was stirred for 12 hours. After the reaction was completed, the reactor was cooled to room temperature, and the unreacted CO2 was slowly released. Then, vacuum devolatilization was performed (the vacuum system was turned on, the vacuum degree was maintained at -0.09 MPa, and the reactor was stirred and extracted at 60°C for 60 minutes to remove the residual propylene oxide monomer), resulting in a viscous liquid, which is the copolymerized modified polypropylene carbonate copolymer (PPC-PA).
[0034] (2) Take 100 parts by weight of PPC-PA, heat it to 80°C to melt it, then add 21 parts by weight of hexamethylene diisocyanate (HDI), 6 parts by weight of 1,4-butanediol (BDO), and 0.05 parts by weight of a composite catalyst (obtained by mixing organic bismuth and triethanolamine at a mass ratio of 2:1). React at 80°C for 4 hours. After the reaction is completed, pour the reactants into a mold preheated to 90°C and cure at 90°C for 8 hours. After demolding, place the elastomer in an 80°C oven for post-curing treatment and let it stand for 24 hours to obtain the final product.
[0035] Example 3 A method for preparing a carbon dioxide-based polypropylene carbonate elastomer includes the following steps: (1) Under anhydrous and oxygen-free conditions, 100 parts by weight of propylene oxide, 30 parts by weight of phthalic anhydride, and 0.15 parts by weight of catalyst A (Zn-Co DMC / [BMIM]BF4 composite catalyst) were added to a high-pressure reactor. After sealing, the air inside the reactor was replaced three times with high-purity CO2. Then, CO2 was introduced until the pressure inside the reactor reached 4.0 MPa. The temperature was raised to 90°C, and the reaction was stirred for 6 hours. After the reaction was completed, the reactor was cooled to room temperature, and the unreacted CO2 was slowly released. Then, vacuum devolatilization was performed (the vacuum system was turned on, the vacuum degree was maintained at -0.09 MPa, and the reactor was stirred and extracted at 60°C for 60 minutes to remove the residual propylene oxide monomer), resulting in a viscous liquid, which is the copolymerized modified polypropylene carbonate copolymer (PPC-PA).
[0036] (2) Take 100 parts by weight of PPC-PA, heat it to 80°C to melt it, then add 24 parts by weight of hexamethylene diisocyanate (HDI), 10 parts by weight of 1,4-butanediol (BDO), and 0.1 parts by weight of a composite catalyst (obtained by mixing organic bismuth and triethanolamine in a mass ratio of 3:1). Heat the mixture to 90°C and react for 2 hours. After the reaction is complete, pour the reactants into a mold preheated to 90°C and cure it at 90°C for 8 hours. After demolding, place the elastomer in an 80°C oven for post-curing treatment and let it stand for 24 hours to obtain the final product.
[0037] Comparative Example 1 The difference between this comparative example and Example 1 is that the catalyst A used in step (1) is an equal amount (0.1 parts by weight) of unmodified zinc-cobalt bimetallic cyanide (Zn-Co DMC), and no imidazole ionic liquid composite is added. The remaining steps are the same as in Example 1.
[0038] Comparative Example 2 The difference between this comparative example and Example 1 is that the catalyst A used in step (1) is an equal amount (0.1 parts by weight) of imidazole ionic liquid [BMIM]BF4, which does not contain zinc-cobalt bimetallic cyanide. The remaining steps are the same as in Example 1.
[0039] Results: Under these conditions, polymerization was almost impossible to initiate, and the reactor contained a mixture of raw materials after the reaction, with no viscous products generated.
[0040] Comparative Example 3 The difference between this comparative example and Example 1 is that in step (1), catalyst A (Zn-Co DMC / [BMIM]BF4 composite catalyst) is replaced with an equal amount of Zn-Fe DMC / [BMIM]BF4 composite catalyst, and the remaining steps are the same as in Example 1.
[0041] Preparation of Zn-Fe DMC / [BMIM]BF4 composite catalyst: ZnCl2 (5.0 g) and K3Fe(CN)6 (2.5 g) were mixed, 1.5 mL of tert-butanol was added, and zirconia grinding beads (ball-to-material mass ratio of 10:1) were placed in the mixture. The mixture was then ball-milled in a planetary ball mill at 300 rpm for 3 hours. After ball milling, the mixture was passed through a 200-mesh sieve, washed three times with a tert-butanol-water mixture (volume ratio of 1:4), and vacuum-dried at 80 °C for 2 hours to obtain Zn-Fe DMC.
[0042] (2) Mix the above Zn-Fe DMC with [BMIM]BF4 (0.3g) and ball mill for 1 hour as above. After ball milling, pass the mixture through a 200-mesh sieve to separate the catalyst powder from the zirconium oxide ball milling beads. Dry under vacuum at 80°C for 2 hours to obtain the final product.
[0043] Comparative Example 4 The difference between this comparative example and Example 1 is that in step (2), the composite catalyst (obtained by mixing organic bismuth and triethanolamine at a mass ratio of 2.5:1) is replaced with an equal amount (0.05 parts by weight) of dibutyltin dilaurate (DBTDL). The remaining steps are the same as in Example 1.
[0044] Comparative Example 5 The difference between this comparative example and Example 1 is that in step (2), the composite catalyst (obtained by mixing organic bismuth and triethanolamine at a mass ratio of 2.5:1) is replaced with a single organic bismuth catalyst (0.05 parts by weight), and triethanolamine is not added. The remaining steps are the same as in Example 1.
[0045] Comparative Example 6 The difference between this comparative example and Example 1 is that in step (2), the composite catalyst (obtained by mixing organic bismuth and triethanolamine at a mass ratio of 2.5:1) is replaced with triethanolamine alone (0.05 parts by weight), and no organic bismuth catalyst is added. The remaining steps are the same as in Example 1.
[0046] Comparative Example 7 The difference between this comparative example and Example 1 is that the amount of HDI used in step (2) is 35 parts. The remaining steps are the same as in Example 1.
[0047] Effect test Tensile strength and elongation at break: refer to GB / T 1040.1-2018, tensile rate 500 mm / min.
[0048] Glass transition temperature (Tg): Referencing GB / T 19466.2-2004, the differential scanning calorimetry (DSC) method was used, with a heating rate of 10℃ / min and a test range of -50℃ to 100℃.
[0049] Compression set: Refer to GB / T 7759-2015, test conditions 70℃×25%, compression rate×22h.
[0050] Water absorption rate: Refer to GB / T 1034-2008, soak in distilled water at 25℃ for 24 hours.
[0051] The test results are shown in Table 1.
[0052] Table 1 Test Results
[0053] As can be seen from the test data in Table 1, the carbon dioxide-based polypropylene carbonate elastomers prepared in Examples 1-3 of this invention exhibit excellent comprehensive mechanical properties, thermal properties, elastic recovery and water resistance. All indicators are significantly better than those of the comparative examples, which fully verifies the rationality and synergy of the formulation and process parameters of this invention.
[0054] Comparative Example 1 used a pure Zn-Co DMC catalyst, and Comparative Example 3 used a Zn-Fe DMC / imidazolium ionic liquid composite catalyst. The effects of both were significantly worse than those of the embodiments of this invention. Furthermore, Comparative Example 2, using only the imidazolium ionic liquid, failed to initiate the polymerization reaction. This demonstrates that the catalyst A, a combination of Zn-Co DMC and imidazolium ionic liquid selected in this invention, can achieve a synergistic catalytic effect, effectively improving the copolymerization efficiency and optimizing the molecular structure of the PPC-PA copolymer.
[0055] Comparative Example 5 used a single organic bismuth catalyst, and Comparative Example 6 used a single triethanolamine catalyst; both showed significantly inferior performance compared to the examples. Comparative Example 4 used a traditional tin-based catalyst (dibutyltin dilaurate), and although its performance was close to that of the examples, the organic bismuth-triethanolamine composite catalyst of this invention is an environmentally friendly catalyst with no heavy metal residues, and it has a slight advantage in elastic recovery and water resistance. This demonstrates that the composite crosslinking catalyst of this invention can stabilize the active center through coordination, improve catalytic efficiency, achieve a mild and controllable crosslinking reaction, and ensure the high elasticity and low permanent deformation characteristics of the elastomer.
[0056] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.
Claims
1. A carbon dioxide-based polypropylene carbonate elastomer, characterized in that, It consists of the following parts by weight of raw materials: The mixture comprises 90-110 parts of copolymerized modified polypropylene carbonate copolymer, 20-30 parts of isocyanate, 5-12 parts of chain extender, and 0.03-0.1 parts of composite catalyst, wherein the composite catalyst is composed of organic bismuth and triethanolamine in a mass ratio of 2-3:
1.
2. The carbon dioxide-based polypropylene carbonate elastomer according to claim 1, characterized in that, The preparation method of the copolymerized modified polypropylene carbonate copolymer includes: Propylene oxide, anhydride monomer, and catalyst A are added to a reactor, carbon dioxide is introduced, and a ring-opening copolymerization reaction is carried out to obtain a copolymerized modified polypropylene carbonate copolymer; wherein, the mass ratio of propylene oxide, anhydride monomer, and catalyst A is 100:15-30:0.05-0.2, and the anhydride monomer is selected from at least one of succinic anhydride, maleic anhydride, and phthalic anhydride.
3. The carbon dioxide-based polypropylene carbonate elastomer according to claim 2, characterized in that, The preparation method of catalyst A includes: (1) Add zinc chloride and potassium cobalt cyanide to a ball mill jar, add tert-butanol, ball mill the reaction, wash, and dry to obtain Zn-CoDMC; (2) Mix Zn-Co DMC with imidazole ionic liquid, ball mill and compound, dry and sieve to obtain catalyst A.
4. The carbon dioxide-based polypropylene carbonate elastomer according to claim 3, characterized in that, In step (1), the molar ratio of zinc chloride to potassium cobalt cyanide is 3-8:1, the amount of tert-butanol used is 1%-5% of the zinc salt mass, the washing uses a mixture of water and tert-butanol with a volume ratio of 1:3-5, and the washing is performed 3-5 times; in step (2), the mass ratio of Zn-Co DMC to imidazole ionic liquid is 100:1-10, the imidazole ionic liquid is selected from at least one of 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate, and the sieve mesh size is 180-220 mesh.
5. The carbon dioxide-based polypropylene carbonate elastomer according to claim 4, characterized in that, In steps (1) and (2), the ball milling speed is 200-500 rpm and the ball milling time is 1-5 h. The drying temperature is 70-90℃ and the drying time is 2-4 h.
6. The carbon dioxide-based polypropylene carbonate elastomer according to claim 2, characterized in that, The carbon dioxide pressure in the reactor is 2.0-4.0 MPa, the temperature of the ring-opening copolymerization reaction is 60-90℃, the time of the ring-opening copolymerization reaction is 6-12 h, and the reaction liquid is depressurized and devolatilized after the ring-opening copolymerization reaction.
7. The carbon dioxide-based polypropylene carbonate elastomer according to claim 1, characterized in that, The preparation method of the composite catalyst includes: mixing organic bismuth with triethanolamine evenly to obtain the catalyst.
8. The carbon dioxide-based polypropylene carbonate elastomer according to claim 1, characterized in that, The isocyanate is selected from at least one of diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and terephthalic diisocyanate; the chain extender is selected from at least one of 1,4-butanediol, ethylene glycol, diethylene glycol, and 1,6-hexanediol.
9. A method for preparing the carbon dioxide-based polypropylene carbonate elastomer according to any one of claims 1-8, characterized in that, Includes the following steps: The copolymerized modified polypropylene carbonate copolymer is mixed with isocyanate, chain extender and composite catalyst, and reacted. The reaction product is then cast, cured and post-cured to obtain the final product.
10. The preparation method according to claim 9, characterized in that, The reaction temperature is 70-90℃, and the reaction time is 2-4 hours; the curing temperature is 80-100℃, and the curing time is 6-8 hours; the post-curing temperature is 70-90℃, and the post-curing time is 22-26 hours.