A method for preparing bio-based polycarbonate

Abstract

This invention discloses a method for preparing bio-based polycarbonate, belonging to the field of polymer materials technology. This method introduces a highly efficient catalyst (nano-cerium oxide) into the polyisosorbate preparation system through specific steps, precise control of reactant ratios, pre-activation treatment, and the use of antioxidants, achieving the preparation of high-bio-based, high-hardness, and high-performance polyisosorbate. This method not only simplifies the traditional polycarbonate material preparation process and reduces production costs, but also improves the environmental friendliness and sustainability of the product, solving many problems faced by traditional polycarbonate materials in the current market.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a method for preparing bio-based polycarbonate by direct polycondensation of isosorbide and carbon dioxide. Background Technology

[0002] With the development of polycarbonate materials, various high-performance polycarbonates have been widely used. However, these products still face some challenges in practical applications. For example, traditional polycarbonate materials on the market generally suffer from low biomass content, insufficient hardness, and poor environmental friendliness. Bisphenol A (BPA) type polycarbonates, in particular, have faced increasing restrictions and demand for alternatives in recent years due to the potential harm of their raw material, bisphenol A, to human health and the environment. Therefore, the development of novel bio-based polycarbonates has become a key research focus.

[0003] To improve the performance of polycarbonate, some research institutions and companies have attempted to prepare high-performance polycarbonate by improving synthesis processes and selecting novel raw materials. However, such improvements often face problems such as high raw material costs, complex synthesis processes, and unstable product performance.

[0004] A search revealed patent CN110869415B, published on June 17, 2022. This patent relates to a polycarbonate copolymer with low specific gravity and high surface hardness. While this polycarbonate copolymer exhibits certain advantages in terms of specific gravity and surface hardness, its main raw material still relies on traditional bisphenol A or other aromatic phenols, with a low proportion of bio-based raw materials, resulting in insufficient environmental friendliness and sustainability. Furthermore, the synthesis process of this patent is relatively complex, requiring sophisticated production equipment and process control, thus limiting its large-scale industrial application.

[0005] A search revealed patent CN110225934B, published on August 3, 2021. This patent provides a polycarbonate resin with excellent scratch resistance, impact resistance, heat resistance, and amine resistance. This polycarbonate resin improves the overall performance of the material through a special structural design. However, this patent also relies on traditional bisphenol A or other aromatic phenols as raw materials, with a low proportion of bio-based raw materials, making it difficult to meet current high requirements for environmental friendliness and sustainability. Furthermore, the synthesis process of this patent is relatively complex, resulting in high production costs, which limits its widespread application.

[0006] The aforementioned problems indicate that traditional polycarbonates currently on the market are insufficient to effectively meet the high requirements for environmental friendliness and sustainability. Therefore, this invention provides a method for preparing bio-based polycarbonate to overcome these shortcomings and provide a novel polycarbonate material that is more bio-based, has higher hardness, and higher performance. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for preparing bio-based polycarbonate with high bio-based properties, high hardness and high performance.

[0008] The technical solution adopted by this invention to solve its technical problem is: a method for preparing bio-based polycarbonate, characterized in that the synthetic route is as follows:

[0009] .

[0010] This invention provides a method for preparing bio-based polycarbonate, the method comprising the following steps:

[0011] 1) Dissolve isosorbide in a high-boiling-point solvent to form a reaction solution;

[0012] 2) Add 1% to 5% of the weight of isosorbide to the reaction solution as a catalyst. The cerium oxide is preferably made of nano-sized particles to increase its surface area and activity and promote reaction efficiency.

[0013] 3) Carbon dioxide is continuously bubbled into the reaction system until the amount of isosorbide is completely reacted. The bubbling pressure is 1.2 MPa to 4.0 MPa. The reaction temperature is controlled at 180℃ to 230℃. Under this temperature condition, isosorbide reacts selectively with carbon dioxide to form carbonate chain segments.

[0014] 4) During the reaction, the solvent is continuously recycled through a reflux condenser, and the generated water is continuously evaporated from the reaction system through a dehydration device to avoid the reverse reaction of water on the esterification reaction and ensure that the reaction proceeds in the direction of polymerization.

[0015] 5) Add 1.5 to 3 equivalents of isosorbide to the reaction system as a dehydrating agent. This dehydrating agent can be selected from nitrile compounds, acetals, molecular sieves, etc., to further capture the water generated during the reaction, ensure the dryness of the reaction system, and thus promote the efficient extension and polymerization of carbonate chains.

[0016] This invention is the first to propose a method for directly synthesizing polyisosorbate carbonate from isosorbide and carbon dioxide by adjusting the ratio of high-boiling-point solvent to isosorbide and the amount of cerium oxide catalyst added. Both isosorbide and carbon dioxide can be prepared using bio-based methods, and the bio-based content of the obtained polyisosorbate carbonate can reach 100%. Furthermore, the molecular weight and degree of polymerization of the bio-based polyisosorbate carbonate can be precisely controlled by adjusting the reaction conditions.

[0017] Specifically, the ratio of isosorbide to a high-boiling-point solvent is set between 1:10 and 50, preferably between 1:20 and 35; the high-boiling-point solvent includes triethylene glycol dimethyl ether, diethylene glycol monobutyl ether, or isosorbide dimethyl ether. By adjusting this ratio, the solubility of the reactants can be effectively controlled, ensuring uniform dispersion of the reactants in the reaction system, improving reaction efficiency, and thus affecting the molecular weight and hardness of the polymer. Simultaneously, by controlling the particle size of cerium oxide to be between 10 nm and 50 nm, and its weight percentage in the reaction system to be between 1% and 5%, particularly preferably between 2% and 4%, this invention achieves effective regulation of the polymerization reaction rate and chain growth mechanism, resulting in a more uniform structure and superior performance of bio-based polycarbonate.

[0018] In a more preferred embodiment of the present invention, a specific pre-reaction step is employed: before dissolving isosorbide in a high-boiling-point solvent, isosorbide is pre-activated. This pre-activation treatment includes adding 5% methanol to isosorbide, stirring the mixture at 60°C to 80°C for 100 to 150 minutes, and then dissolving the activated isosorbide in the high-boiling-point solvent. This pre-activation treatment effectively improves the reactivity of isosorbide molecules, reduces the formation of reaction byproducts, and improves the purity and performance of the final product. This process not only eliminates the need for additional complex equipment but can also be completed using existing reaction vessels and stirring devices, resulting in low cost and ease of operation.

[0019] Nitrile compounds used as dehydrating agents include acetonitrile, propionitrile, butadiene nitrile, benzonitrile, and trimeronitrile; the acetals include dimethoxymethane, 1,3-dioxolane, triethyl orthoformate, and 2,2-dimethoxypropane.

[0020] Furthermore, this invention innovatively incorporates an antioxidant during the reaction process, preferably ascorbic acid or its derivatives, accounting for 0.1% to 1% of the total reactants, more preferably 0.3% to 0.5%. The addition of the antioxidant effectively prevents the degradation of bio-based polycarbonate under high temperature and high activity conditions, ensuring the stability of the polymer's molecular weight and structure, and improving the product's durability and service life.

[0021] The innovation of this invention lies in introducing a highly efficient catalyst (nano-cerium oxide), precise control of reactant ratios, pre-activation treatment, and the use of antioxidants into the bio-based polycarbonate preparation system through the specific methods and steps described above. This achieves the preparation of bio-based polycarbonates with high bio-based content, high hardness, and high performance. The method of this invention not only simplifies the traditional polycarbonate material preparation process and reduces production costs, but also improves the environmental friendliness and sustainability of the product, solving many problems faced by traditional polycarbonate materials in the current market.

[0022] The working principle of this invention lies in using isosorbide (a diol derived from renewable biomass) as a raw material, reacting it with carbon dioxide under highly efficient nano-cerium oxide catalysis. By precisely controlling the reaction conditions (such as the ratio of solvent to isosorbide, the type and amount of catalyst, and the reaction temperature), and employing a pre-activation treatment process and antioxidant protection, a bio-based polycarbonate with high bio-based content, high hardness, and high performance is ultimately obtained. The bio-based polycarbonate prepared by this method exhibits excellent physicochemical properties, particularly in hardness, heat resistance, and environmental adaptability, making it suitable for use in the manufacture of high-end engineering plastics, biomedical materials, and packaging materials.

[0023] The advantages of this invention are:

[0024] By using renewable isosorbide as the main raw material, the biomass content of the product has been increased, meeting the current market's high requirements for environmental friendliness and sustainability.

[0025] By using nano-cerium oxide catalysts and optimized reaction conditions, the synthesis efficiency and selectivity of bio-based polycarbonates were significantly improved, the formation of by-products was reduced, and the purity and performance of the products were enhanced.

[0026] By introducing pre-activation treatment and antioxidant protection, the preparation process is simplified and production costs are reduced, while the stability and durability of the product are improved, demonstrating significant industrial application value.

[0027] The invented bio-based polycarbonate significantly improves the bio-based content and environmental friendliness of polycarbonate by using isosorbide as the main raw material. Furthermore, through optimized synthesis processes, the polycarbonate of this invention exhibits significant improvements in hardness, heat resistance, and mechanical properties, making it suitable for a variety of high-performance applications. Therefore, this invention provides a more intelligent, efficient, and adaptable method for preparing novel polycarbonate materials in varying environments.

[0028] Compared with existing technologies, this invention has the following beneficial effects: This invention provides a novel method for preparing bio-based, high-hardness, and high-performance bio-based polycarbonate. This method not only significantly improves the performance of polycarbonate materials while solving problems such as low biomass content, insufficient hardness, and poor environmental friendliness in traditional polycarbonate materials, but also greatly simplifies the synthesis process, reduces production costs, and improves product stability and environmental adaptability. The innovation of this invention lies in achieving the efficient preparation of bio-based polycarbonate with high biomass content through specific reaction conditions and raw material combinations. Detailed Implementation

[0029] The present invention will now be described in detail through examples. Unless otherwise stated, all raw materials used are commercially available.

[0030] Example 1

[0031] 1) Add 5% methanol to isosorbide and stir at 70℃ for 120 min for pre-activation treatment; dissolve the pre-activated isosorbide in triethylene glycol dimethyl ether to form a reaction solution, with the mass ratio of isosorbide to triethylene glycol dimethyl ether being 1:30; add 3% cerium oxide by weight of isosorbide to the reaction solution as a catalyst, with the particle size of cerium oxide controlled at 10~50 nm.

[0032] 2) Continuously bubble carbon dioxide into the reaction system at a pressure of 2.5 MPa, and simultaneously add ascorbate palmitate at a rate of 0.5% of the total mass of the reactants; control the reaction temperature at 200℃ until isosorbide is completely reacted.

[0033] 3) Add 2 equivalents of isosorbide to the reaction system, and simultaneously circulate the solvent through a reflux condenser and evaporate the generated water from the reaction system through a dehydration device. After the reaction is completed, bio-based polycarbonate is obtained by methanol precipitation, washing, and drying. The mass content of the components that conform to the structural formula in the obtained bio-based polycarbonate is 96.6% by real-time determination using nuclear magnetic resonance and Fourier transform infrared spectroscopy.

[0034] Example 2

[0035] The basic process is the same as in Example 1, except that isosorbide was not pre-activated in step 1); the mass content of the component conforming to the structural formula in the obtained bio-based polycarbonate was 94.5% as determined by nuclear magnetic resonance and Fourier transform infrared spectroscopy.

[0036] Example 3

[0037] 1) Add 5% methanol to isosorbide and stir at 65℃ for 130 min for pre-activation treatment; dissolve the pre-activated isosorbide in triethylene glycol dimethyl ether to form a reaction solution, with the mass ratio of isosorbide to triethylene glycol dimethyl ether being 1:20; add 2% cerium oxide by weight of isosorbide to the reaction solution as a catalyst, with the particle size of cerium oxide controlled at 10~50 nm.

[0038] 2) Continuously bubble carbon dioxide into the reaction system at a pressure of 1.5 MPa, and simultaneously add ascorbate palmitate at a rate of 0.5% of the total mass of the reactants; control the reaction temperature at 200℃ until isosorbide is completely reacted.

[0039] 3) Add 2.5 times the amount of isosorbide as a dehydrating agent, benzonitrile, to the reaction system. At the same time, the solvent is recycled through a reflux condenser, and the generated water is evaporated from the reaction system through a dehydration device. After the reaction is completed, bio-based polycarbonate is obtained by methanol precipitation, washing, and drying. The mass content of the components that conform to the structural formula in the obtained bio-based polycarbonate is 96.1% by real-time determination using nuclear magnetic resonance and Fourier transform infrared spectroscopy.

[0040] Example 4

[0041] 1) Add 5% methanol to isosorbide and stir at 75℃ for 110 min for pre-activation treatment; dissolve the pre-activated isosorbide in triethylene glycol dimethyl ether to form a reaction solution, with the mass ratio of isosorbide to triethylene glycol dimethyl ether being 1:40; add 4% cerium oxide by weight of isosorbide as a catalyst to the reaction solution, with the particle size of cerium oxide controlled at 10~50 nm.

[0042] 2) Continuously bubble carbon dioxide into the reaction system at a pressure of 3.0 MPa, and add ascorbic acid at a rate of 0.3% of the total mass of the reactants; control the reaction temperature at 180℃~230℃ until isosorbide reacts completely.

[0043] 3) Add 1.8 times the amount of isosorbide as a dehydrating agent, 1,3-dioxolane, to the reaction system. At the same time, the solvent is recycled through a reflux condenser, and the generated water is evaporated from the reaction system through a dehydration device. After the reaction is completed, bio-based polycarbonate is obtained by methanol precipitation, washing, and drying. The mass content of the components that conform to the structural formula in the obtained bio-based polycarbonate is 95.7% by real-time determination using nuclear magnetic resonance and Fourier transform infrared spectroscopy.

[0044] Example 5

[0045] 1) Add 5% methanol to isosorbide and stir at 60℃ for 150 min for pre-activation treatment; dissolve the pre-activated isosorbide in diethylene glycol monobutyl ether to form a reaction solution, with the mass ratio of isosorbide to diethylene glycol monobutyl ether being 1:50; add 1% cerium oxide by weight of isosorbide to the reaction solution as a catalyst, with the particle size of cerium oxide controlled at 10~50 nm.

[0046] 2) Continuously bubble carbon dioxide into the reaction system at a pressure of 1.2 MPa, and add ascorbic acid at a rate of 1% of the total mass of the reactants; control the reaction temperature at 180℃ until isosorbide is completely reacted.

[0047] 3) Add 1.5 to 3 times the amount of isosorbide as a dehydrating agent, dimethoxymethane, to the reaction system. At the same time, the solvent is recycled through a reflux condenser, and the generated water is evaporated from the reaction system through a dehydration device. After the reaction is completed, bio-based polycarbonate is obtained by methanol precipitation, washing, and drying. The mass content of the components that conform to the structural formula in the obtained bio-based polycarbonate is 93.1% by real-time determination using nuclear magnetic resonance and Fourier transform infrared spectroscopy.

[0048] Example 6

[0049] 1) Add 5% methanol to isosorbide and stir at 80℃ for 100 min for pre-activation treatment; dissolve the pre-activated isosorbide in triethylene glycol dimethyl ether to form a reaction solution, with the mass ratio of isosorbide to triethylene glycol dimethyl ether being 1:10; add 5% cerium oxide by weight of isosorbide to the reaction solution as a catalyst, with the particle size of cerium oxide controlled at 10~50 nm;

[0050] 2) Continuously bubble carbon dioxide into the reaction system at a pressure of 4.0 MPa, and simultaneously add ascorbate palmitate at a rate of 0.1% of the total mass of the reactants; control the reaction temperature at 230℃ until isosorbide is completely reacted.

[0051] 3) Add 1.5 times the amount of isosorbide as a dehydrating agent, succinate, to the reaction system. At the same time, use a reflux condenser to recycle the solvent and use a dehydration device to evaporate the generated water from the reaction system. After the reaction is completed, precipitate with methanol, wash, and dry to obtain bio-based polycarbonate. The mass content of the components that conform to the structural formula in the obtained bio-based polycarbonate is 93.3% by nuclear magnetic resonance and Fourier transform infrared spectroscopy.

[0052] The performance comparisons of the bio-based polycarbonate prepared in the embodiments of the present invention are shown in Table 1. The glass transition temperature (Tg) was determined using differential scanning calorimetry (DSC), tensile strength and elongation at break were tested according to ISO 527 standard, and Rockwell hardness was tested according to ASTM D785 standard.

[0053] Table 1

[0054] Example Tg (°C) Tensile strength (MPa) Elongation at break (%) Rockwell hardness (R scale) Example 1 126 78 12 122 Example 2 119 72 18 118 Example 3 128 80 10 124 Example 4 122 75 15 120 Example 5 114 68 22 115 Example 6 129 82 8 126

[0055] The Tg values ​​of the embodiments of the present invention are all much higher than those of traditional carbon dioxide copolymer polycarbonates, which is due to the rigid furan ring structure of isosorbide.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing polyisosorbate carbonate, characterized in that, The synthetic route is as follows: ； The preparation steps are as follows: Isosorbide is dissolved in a high-boiling-point solvent to form a reaction solution; cerium oxide, accounting for 1% to 5% of the weight of isosorbide, is added to the reaction solution as a catalyst; carbon dioxide is continuously bubbled into the reaction system, and the reaction temperature is controlled at 180℃ to 230℃ until isosorbide is completely reacted; the solvent is recycled through a reflux condenser, and the generated water is evaporated from the reaction system through a dehydration device; Before dissolving isosorbide in a high-boiling-point solvent, isosorbide is pre-activated. This pre-activation process includes adding 5% methanol to isosorbide and stirring the mixture at 60°C–80°C for 100–150 min. Then, 1.5–3 times the equivalent of a dehydrating agent is added to the reaction system. The dehydrating agent is a nitrile compound, acetal, or molecular sieve. The nitrile compound includes acetonitrile, propionitrile, butadiene nitrile, benzonitrile, and trimeronitrile. The acetal includes dimethoxymethane, 1,3-dioxolane, triethyl orthoformate, and 2,2-dimethoxypropane. The mass ratio of isosorbide to a high-boiling-point solvent is 1:10 to 50, and the high-boiling-point solvent includes triethylene glycol dimethyl ether, diethylene glycol monobutyl ether, or isosorbide dimethyl ether.

2. The method for preparing polyisosorbate carbonate according to claim 1, characterized in that, The particle size of the cerium oxide is controlled to be 10-50 nanometers.

3. The method for preparing polyisosorbate carbonate according to claim 1, characterized in that, The carbon dioxide is introduced at a pressure of 1.2 MPa to 4.0 MPa.

4. The method for preparing polyisosorbate carbonate according to claim 1, characterized in that, An antioxidant is added during the reaction, the antioxidant being selected from ascorbic acid or its derivatives, and the amount added is 0.1% to 1% of the total mass of the reactants.

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