Preparation method of bio-based polycarbonate

Abstract

The invention discloses a preparation method of bio-based polycarbonate, and belongs to the technical field of high polymer materials. According to the method, an efficient catalyst (nano cerium oxide) is introduced into a polyisosorbide carbonate preparation system through specific method steps, and preparation of polyisosorbide carbonate with high bio-based content, high hardness and high performance is realized through accurate reactant proportion control, a pre-activation treatment process and use of an antioxidant. According to the method disclosed by the invention, the preparation process of the traditional polycarbonate material is simplified, the production cost is reduced, the environmental friendliness and sustainability of the product are also improved, and many problems faced by the traditional polycarbonate material in the existing market are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a preparation method of a bio-based polycarbonate directly polycondensed from isosorbide and carbon dioxide. Background Art

[0002] With the development of polycarbonate materials, various high-performance polycarbonates have been widely used. However, there are still some problems in their actual use. For example, traditional polycarbonate materials on the market generally have problems such as low biomass content, insufficient hardness, and poor environmental friendliness. Especially bisphenol A type polycarbonate, due to its raw material bisphenol A may pose potential hazards to human health and the environment, it has been increasingly restricted and in need of replacement in recent years. Therefore, the development of new bio-based polycarbonates has become the focus of research.

[0003] In order to improve the performance of polycarbonate, some research institutions and enterprises have tried to prepare high-performance polycarbonates by improving the synthesis process and selecting new raw materials. However, such improvements often face problems such as high raw material costs, complex synthesis processes, and unstable product performance.

[0004] After retrieval, the patent with the publication number CN110869415B was published on June 17, 2022. This patent relates to a polycarbonate copolymer with a low specific gravity and high surface hardness. Although this polycarbonate copolymer shows certain advantages in specific gravity and surface hardness, its main raw materials still rely on traditional bisphenol A or other aromatic phenols, and the proportion of bio-based raw materials used is relatively low, with insufficient environmental friendliness and sustainability. In addition, the synthesis process of this patent is relatively complex, with high requirements for production equipment and process control, which limits its large-scale industrial application.

[0005] After retrieval, the patent with the publication number CN110225934B was published on August 3, 2021. This patent provides a polycarbonate resin with excellent scratch resistance, impact resistance, heat resistance, and amine resistance. Through the design of a special structure, the comprehensive performance of the material is improved. However, this patent also relies on traditional bisphenol A or other aromatic phenols as raw materials, and the proportion of bio-based raw materials used is relatively low, making it difficult to meet the current high requirements for environmental friendliness and sustainability. In addition, the synthesis process of this patent is also relatively complex, with high production costs, which limits its promotion in practical applications.

[0006] The above problems indicate that traditional polycarbonates on the market are difficult to effectively meet the high requirements for environmental friendliness and sustainability. Therefore, the present invention provides a preparation method of a bio-based polycarbonate to overcome these deficiencies and provide a new type of polycarbonate material that is more bio-based, has high hardness, and high performance. Summary of the Invention

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

[0008] The technical solution adopted by the present invention to solve its technical problems is: a preparation method of a bio-based polycarbonate, characterized in that the synthesis route is:

[0009] 。

[0010] The present invention provides a preparation method of a bio-based polycarbonate, and the method comprises the following steps:

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

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

[0013] 3) Continuously introduce carbon dioxide into the reaction system until the amount of isosorbide is completely reacted, and the introduction pressure is 1.2 MPa - 4.0 MPa; the reaction temperature is controlled at 180°C - 230°C. Under this temperature condition, the selective reaction of isosorbide and carbon dioxide forms carbonate linkages;

[0014] 4) During the reaction process, the solvent is continuously recycled through a condensation reflux device, and at the same time, the generated water is continuously volatilized from the reaction system through a dehydration device to avoid the reverse reaction effect of water on the esterification reaction and ensure that the reaction proceeds in the direction of polymerization;

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

[0016] The present invention first proposes to directly synthesize polyisosorbide carbonate from isosorbide and carbon dioxide by adjusting the ratio of the high-boiling solvent to isosorbide and the addition amount of the cerium oxide catalyst. Both isosorbide and carbon dioxide can be prepared by bio-based methods, and the bio-based content of the prepared polyisosorbide carbonate can reach 100%; and the molecular weight and degree of polymerization of the bio-based polyisosorbide carbonate can be accurately controlled by reaction conditions.

[0017] Specifically, the ratio of isosorbide to the high-boiling solvent is set between 1:10 and 50, preferably 1:20 to 35; the high-boiling 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 the uniform dispersion of the reactants in the reaction system, improving the reaction efficiency, and thus affecting the molecular weight and hardness of the polymer. At the same time, 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%, especially preferably between 2% and 4%, the present invention realizes the effective regulation of the polymerization reaction rate and the chain growth mechanism, and obtains a bio-based polycarbonate with a more uniform structure and superior performance.

[0018] In a more preferred embodiment of the present invention, a specific pre-reaction step is adopted, that is, before dissolving isosorbide in the high-boiling solvent, isosorbide is pre-activated. This pre-activation treatment includes adding 5% methanol to isosorbide, stirring and reacting at 60 °C to 80 °C for 100 min to 150 min, and then dissolving the activated isosorbide in the high-boiling solvent. The pre-activation treatment can effectively improve the reaction activity of isosorbide molecules, reduce the generation of reaction by-products, and improve the purity and performance of the final product. This process not only does not require additional complex equipment, but also can be completed using existing reaction kettles and stirring devices, with low cost and easy operation.

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

[0020] In addition, the present invention also innovatively adds an antioxidant during the reaction process, preferably ascorbic acid or its derivatives, accounting for 0.1% to 1% of the total amount of reactants, preferably 0.3% to 0.5%. The addition of the antioxidant can effectively prevent the degradation of the bio-based polycarbonate under high-temperature and high-activity conditions, ensure the stability of the molecular weight and structure of the polymer, and improve the durability and service life of the product.

[0021] The innovation of the present invention lies in introducing an efficient catalyst (nano-ceria), precise control of the reactant ratio, pre-activation treatment process, and the use of an antioxidant into the bio-based polycarbonate preparation system through the above specific method steps, thereby realizing the preparation of a bio-based polycarbonate with a high bio-based content, high hardness, and high performance. The method of the present invention not only simplifies the preparation process of traditional polycarbonate materials, reduces the production cost, but also improves the environmental friendliness and sustainability of the product, and solves many problems faced by traditional polycarbonate materials in the existing market.

[0022] The working principle of the present invention lies in using isosorbide (a diol derived from renewable biomass) as a raw material, reacting it with carbon dioxide under the catalysis of highly efficient nano-ceria, and through precisely controlling reaction conditions (such as the ratio of solvent to isosorbide, the type and amount of catalyst, reaction temperature, etc.) and adopting a pre-activation treatment process and the protection of antioxidants, a bio-based polycarbonate with a high bio-based content, high hardness, and high performance is finally obtained. The bio-based polycarbonate prepared by this method has good physical and chemical properties, especially excellent performance in terms of hardness, heat resistance, and environmental adaptability, and is suitable for manufacturing high-end engineering plastics, biomedical materials, packaging materials, and other fields.

[0023] The advantages of the present invention are as follows:

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

[0025] Through the nano-ceria catalyst and optimized reaction conditions, the synthesis efficiency and selectivity of the bio-based polycarbonate are significantly improved, the generation of by-products is reduced, and the purity and performance of the product are enhanced.

[0026] By introducing pre-activation treatment and the protection of antioxidants, not only the preparation process is simplified, the production cost is reduced, but also the stability and durability of the product are improved, having significant industrial application value.

[0027] The bio-based polycarbonate of the invention, by using isosorbide as the main raw material, significantly increases the bio-based content and environmental friendliness of the polycarbonate. In addition, through optimizing the synthesis process, the polycarbonate of the present invention shows significant improvements in terms of hardness, heat resistance, and mechanical properties, and can be applied to a variety of high-performance application fields. Therefore, the present invention provides a new method for preparing a more intelligent, efficient, and environmentally adaptable new polycarbonate material.

[0028] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a new method for preparing a bio-based, high-hardness, and high-performance bio-based polycarbonate. This method can not only significantly improve the performance of the polycarbonate material while solving the problems of low biomass content, insufficient hardness, and poor environmental friendliness of traditional polycarbonate materials, but also greatly simplify the synthesis process, reduce the production cost, and improve the stability and environmental adaptability of the product. The innovation of the present invention lies in the efficient preparation of a bio-based polycarbonate with a high bio-based content through specific reaction conditions and raw material combinations. Detailed implementation manners

[0029] The present invention will be specifically described below through examples. Unless otherwise stated, all raw materials are commercially available.

[0030] Example 1

[0031] 1) Add 5% methanol to isosorbide, and carry out pre-activation treatment by stirring reaction at 70 °C for 120 min; dissolve the pre-activated isosorbide in triethylene glycol dimethyl ether to form a reaction solution, and the mass ratio of isosorbide to triethylene glycol dimethyl ether is 1:30; add cerium oxide accounting for 3% of the weight of isosorbide as a catalyst to the reaction solution, and control the particle size of cerium oxide within 10 - 50 nanometers;

[0032] 2) Continuously introduce carbon dioxide into the reaction system at an introduction pressure of 2.5 MPa, and simultaneously add ascorbyl palmitate with an addition amount accounting for 0.5% of the total mass of the reactants; control the reaction temperature at 200 °C until the isosorbide completely reacts;

[0033] 3) Add 2 equivalents of succinonitrile to the reaction system based on isosorbide, and at the same time make the solvent recycle through a condensation reflux device, and make the generated water volatilize from the reaction system through a dehydration device; after the reaction is completed, obtain the bio-based polycarbonate through methanol precipitation, washing, and drying, and immediately measure by nuclear magnetic resonance and Fourier transform infrared spectroscopy that the mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate is 96.6%.

[0034] Example 2

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

[0036] Example 3

[0037] 1) Add 5% methanol to isosorbide, and carry out pre-activation treatment by stirring reaction at 65 °C for 130 min; dissolve the pre-activated isosorbide in triethylene glycol dimethyl ether to form a reaction solution, and the mass ratio of isosorbide to triethylene glycol dimethyl ether is 1:20; add cerium oxide accounting for 2% of the weight of isosorbide as a catalyst to the reaction solution, and control the particle size of cerium oxide within 10 - 50 nanometers;

[0038] 2) Continuously introduce carbon dioxide into the reaction system at an introduction pressure of 1.5 MPa, and simultaneously add ascorbyl palmitate with an addition amount accounting for 0.5% of the total mass of the reactants; control the reaction temperature at 200 °C until the isosorbide completely reacts;

[0039] 3) Add 2.5 equivalents of dehydrating agent benzonitrile to the reaction system. At the same time, make the solvent recycle through a condensing reflux device, and make the generated water volatilize from the reaction system through a dehydration device. After the reaction is completed, obtain the bio-based polycarbonate through methanol precipitation, washing, and drying. Immediately measure by nuclear magnetic resonance and Fourier transform infrared spectroscopy that the mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate is 96.1%.

[0040] Example 4

[0041] 1) Add 5% methanol to isosorbide and stir and react at 75 °C for 110 min for pre-activation treatment. Dissolve the pre-activated isosorbide in triethylene glycol dimethyl ether to form a reaction solution, and the mass ratio of isosorbide to triethylene glycol dimethyl ether is 1:40. Add cerium oxide accounting for 4% of the weight of isosorbide as a catalyst to the reaction solution, and control the particle size of cerium oxide at 10 - 50 nanometers.

[0042] 2) Continuously introduce carbon dioxide into the reaction system, with an introduction pressure of 3.0 MPa. At the same time, add ascorbic acid, and the addition amount accounts for 0.3% of the total mass of the reactants. Control the reaction temperature at 180 °C - 230 °C until the isosorbide completely reacts.

[0043] 3) Add 1.8 equivalents of dehydrating agent 1,3-dioxolane to the reaction system. At the same time, make the solvent recycle through a condensing reflux device, and make the generated water volatilize from the reaction system through a dehydration device. After the reaction is completed, obtain the bio-based polycarbonate through methanol precipitation, washing, and drying. Immediately measure by nuclear magnetic resonance and Fourier transform infrared spectroscopy that the mass content of the components conforming to the structural formula in the obtained bio-based polycarbonate is 95.7%.

[0044] Example 5

[0045] 1) Add 5% methanol to isosorbide and stir and react at 60 °C for 150 min for pre-activation treatment. Dissolve the pre-activated isosorbide in diethylene glycol monobutyl ether to form a reaction solution, and the mass ratio of isosorbide to diethylene glycol monobutyl ether is 1:50. Add cerium oxide accounting for 1% of the weight of isosorbide as a catalyst to the reaction solution, and control the particle size of cerium oxide at 10 - 50 nanometers.

[0046] 2) Continuously introduce carbon dioxide into the reaction system, with an introduction pressure of 1.2 MPa. At the same time, add ascorbic acid, and the addition amount accounts for 1% of the total mass of the reactants. Control the reaction temperature at 180 °C until the isosorbide completely reacts.

[0047] 3) Add 1.5 - 3 equivalents of dehydrating agent dimethoxymethane to the reaction system relative to isosorbide. Meanwhile, recycle the solvent through a condensing reflux device, and volatilize the generated water from the reaction system through a dehydration device. After the reaction, obtain the bio - based polycarbonate through methanol precipitation, washing, and drying. Immediately measure by nuclear magnetic resonance and Fourier transform infrared spectroscopy that the mass content of the components conforming to the structural formula in the obtained bio - based polycarbonate is 93.1%.

[0048] Example 6

[0049] 1) Add 5% methanol to isosorbide and stir - react at 80 °C for 100 min for pre - activation treatment. Dissolve the pre - activated isosorbide in triethylene glycol dimethyl ether to form a reaction solution, and the mass ratio of isosorbide to triethylene glycol dimethyl ether is 1:10. Add 5% of cerium oxide by weight of isosorbide as a catalyst to the reaction solution, and control the particle size of cerium oxide at 10 - 50 nm.

[0050] 2) Continuously introduce carbon dioxide into the reaction system at a pressure of 4.0 MPa, and simultaneously add ascorbyl palmitate, with the addition amount accounting for 0.1% of the total mass of the reactants. Control the reaction temperature at 230 °C until isosorbide completely reacts.

[0051] 3) Add 1.5 equivalents of dehydrating agent succinonitrile to the reaction system relative to isosorbide. Meanwhile, recycle the solvent through a condensing reflux device, and volatilize the generated water from the reaction system through a dehydration device. After the reaction, obtain the bio - based polycarbonate through methanol precipitation, washing, and drying. Immediately measure by nuclear magnetic resonance and Fourier transform infrared spectroscopy that the mass content of the components conforming to the structural formula in the obtained bio - based polycarbonate is 93.3%.

[0052] The performance comparison of the bio - based polycarbonates prepared in the examples of the present invention is shown in Table 1. Among them, the glass transition temperature (Tg) is measured by differential scanning calorimetry (DSC), the tensile strength and elongation at break are tested according to the ISO 527 standard, and the Rockwell hardness is tested according to the 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 of the bio - based polycarbonates prepared in the examples of the present invention is much higher than that of traditional carbon dioxide copolymerized polycarbonates, due to the rigid furan ring structure of isosorbide.

[0056] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in any other form. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a bio-based polycarbonate, characterized in that, The synthesis route is as follows: 。 2. The preparation method of a bio-based polycarbonate according to claim 1, characterized in that, The preparation steps are as follows: Dissolve isosorbide in a high-boiling solvent to form a reaction solution; add cerium oxide accounting for 1% - 5% of the weight of isosorbide as a catalyst to the reaction solution; continuously introduce carbon dioxide into the reaction system, and control the reaction temperature at 180°C - 230°C until isosorbide completely reacts; make the solvent recycle through a condensing reflux device, and make the generated water volatilize from the reaction system through a dehydration device.

3. The preparation method of a bio-based polycarbonate according to claim 2, characterized in that, The mass ratio of the isosorbide to the high-boiling solvent is 1:10 - 50, and the high-boiling solvent includes triethylene glycol dimethyl ether, diethylene glycol monobutyl ether or isosorbide dimethyl ether.

4. The preparation method of a bio-based polycarbonate according to claim 2, characterized in that, The particle size of the cerium oxide is controlled at 10 - 50 nanometers.

5. The preparation method of a bio-based polycarbonate according to claim 2, characterized in that, The injection pressure of the carbon dioxide is 1.2 MPa - 4.0 MPa.

6. The preparation method of a bio-based polycarbonate according to claim 2, wherein Before dissolving isosorbide in the high-boiling solvent, pre-activate isosorbide first. The pre-activation treatment includes adding 5% of methanol to isosorbide and stirring and reacting at 60°C - 80°C for 100 min - 150 min.

7. The preparation method of a bio-based polycarbonate according to claim 2, characterized in that, Add 1.5 - 3 times the equivalent of a dehydrating agent of the isosorbide to the reaction system.

8. The preparation method of a bio-based polycarbonate according to claim 7, characterized in that, The dehydrating agent is a nitrile compound, an acetal or a molecular sieve.

9. The preparation method of a bio-based polycarbonate according to claim 8, characterized in that, The nitrile compounds include acetonitrile, propionitrile, succinonitrile, benzonitrile, melamine; the acetals include dimethoxymethane, 1,3-dioxolane, triethyl orthoformate, 2,2-dimethoxypropane.

10. The preparation method of a bio-based polycarbonate according to claim 2, characterized in that, Add an antioxidant during the reaction. The antioxidant is selected from ascorbic acid or its derivatives, and the addition amount accounts for 0.1% - 1% of the total mass of the reactants.

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