A bio-based toughening agent modified isosorbide polycarbonate and its preparation method

Abstract

This invention discloses a bio-based toughening agent-modified isosorbide polycarbonate and its preparation method, belonging to the technical field of isosorbide polycarbonate. The method includes the following steps: synthesis of a star-shaped polyester toughening agent, synthesis of isosorbide-decanediol copolycarbonate, and reactive blending. The method for synthesizing the star-shaped polyester toughening agent involves vacuum drying pentaerythritol at 105-115°C for 0.8-1.2 hours, mixing the dried pentaerythritol with ε-caprolactone and stannous octoate under nitrogen protection, heating to 125-135°C, and stirring the reaction under nitrogen atmosphere for 10-14 hours. After the reaction, cooling to 38-42°C, adding dichloromethane to completely dissolve the product, and precipitating it with cold methanol, followed by drying to obtain the star-shaped polyester toughening agent. The modified isosorbide polycarbonate prepared by this invention exhibits high toughness while maintaining excellent transparency.

Description

Technical Field

[0001] This invention belongs to the technical field of isosorbide polycarbonate, specifically relating to a bio-based toughening agent modified isosorbide polycarbonate and its preparation method. Background Technology

[0002] Isosorbide (ISB), a plant-derived, safe, and readily available bio-based monomer, contains two rigid furan rings in its structure. Polycarbonates prepared from ISB possess advantages such as high glass transition temperature, high mechanical strength, and high modulus, making them promising candidates for engineering plastics. However, isosorbide-based polycarbonates suffer from low toughness, high melt viscosity, and difficulty in processing and molding, severely hindering their industrial application.

[0003] To address the aforementioned issues, existing technologies primarily employ copolymerization modification strategies, copolymerizing isosorbide (ISB) with flexible aliphatic diols to improve the material's flexibility and processing properties. In recent years, Xu Fei, Li Zengxi, and others from the Institute of Process Engineering, Chinese Academy of Sciences, have developed functionalized ionic liquid catalysts and successfully synthesized a copolymerized carbonate of isosorbide and 1,10-decanediol. Studies have shown that the introduction of 1,10-decanediol significantly improves the material's ductility; when the decanediol content is 30 mol%, the copolymer's elongation at break reaches 121%, while the glass transition temperature can be controlled within the range of 20–168°C, effectively improving mechanical properties. This advancement provides an important approach for the performance regulation of bio-based polycarbonates.

[0004] However, the aforementioned studies mainly focused on improving elongation at break and tensile strength, with few reports on the impact resistance of the materials. According to the literature, when the decanediol content is low (≤10 mol%), the copolymer still exhibits brittle fracture characteristics, making tensile testing difficult, indicating that its notched impact strength remains low and its impact resistance is insufficient. CN120795295A discloses a bio-based polycarbonate copolymer and its preparation method, finding that while increasing the decanediol content improves elongation at break, it is accompanied by a decrease in tensile strength. Since impact strength is positively correlated with tensile strength, the impact strength also decreases accordingly.

[0005] Therefore, developing a toughening modification method that can achieve efficient chemical bonding with isosorbide polycarbonate, significantly improve the toughness of the material, and maintain excellent transparency is of great research significance and application value. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a bio-based toughening agent-modified isosorbide polycarbonate and its preparation method. The prepared modified isosorbide polycarbonate exhibits high toughness while maintaining excellent transparency.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing bio-based toughening agent modified isosorbide polycarbonate includes the following steps: synthesizing a star-shaped polyester toughening agent, synthesizing isosorbide-decanediol copolycarbonate, and reactive blending; The method for synthesizing the star-shaped polyester toughening agent is as follows: Pentaerythritol is vacuum dried at 105-115℃ for 0.8-1.2 hours. Under nitrogen protection, the dried pentaerythritol is mixed with ε-caprolactone and stannous octoate, and the mixture is heated to 125-135℃ and stirred under nitrogen atmosphere for 10-14 hours. After the reaction is completed, the mixture is cooled to 38-42℃, and dichloromethane is added to completely dissolve the product. While stirring, the solution is slowly added dropwise to cold methanol, resulting in the precipitation of a white precipitate. The precipitate is collected by filtration and washed with cold methanol. The above dissolution-precipitation operation is repeated once. The final product is vacuum dried at 38-42℃ to constant weight to obtain the star-shaped polyester toughening agent. The molar ratio of pentaerythritol, ε-caprolactone, and stannous octanoate is 10:380-420:0.1-0.14. The temperature of the cold methanol is 0-5℃; The amounts of dichloromethane and cold methanol used are 45-55 times and 160-200 times the mass of pentaerythritol, respectively. The number average molecular weight of the star-shaped polyester toughening agent is 4600-5100.

[0008] The method for synthesizing the isosorbide-decanediol copolycarbonate is as follows: isosorbide, 1,10-decanediol, diphenyl carbonate, and lithium acetylacetonate are mixed, and the air in the reactor is replaced with nitrogen 2-3 times. The temperature is raised to 175-185°C, and the mixture is stirred to completely melt and mix the materials. Then the temperature is raised to 195-205°C, and the distilled phenol is collected. At the same time, the pressure is gradually reduced to 19-21 kPa. The reaction is carried out at this temperature and pressure for 1.4-1.6 hours. Then the temperature is raised to 215-225°C, and the pressure is reduced to below 100 Pa. The reaction is continued for 1.8-2.2 hours. After the reaction is completed, heating is stopped, nitrogen is introduced to release the vacuum, and the polymer is poured out while hot. After cooling, a pale yellow solid isosorbide-decanediol copolycarbonate is obtained. The molar ratio of isosorbide, 1,10-decanediol, diphenyl carbonate, and lithium acetylacetonate is 0.81-0.95:0.08-0.12:1:0.002-0.004.

[0009] The reactive blending method is as follows: isosorbide-decanediol copolycarbonate and star-shaped polyester toughening agent are vacuum dried at 85-95℃ for 3.5-4.5 hours. The two materials are thoroughly shaken and mixed in a sealed container. The mixture is heated to 200-210℃ and melt-blended under nitrogen protection for 6.5-7.5 minutes. After blending, heating is stopped, the blend is taken out, cooled to room temperature, and pelletized to obtain modified isosorbide polycarbonate. The mass ratio of isosorbide-decanediol copolycarbonate to star-shaped polyester toughening agent is 100:8-12.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention proposes to reactively blend a star-shaped polycaprolactone toughening agent with isosorbide-decanediol copolycarbonate. Utilizing the lithium acetylacetone catalyst remaining from the copolycarbonate synthesis process, the multi-arm terminal hydroxyl groups of the star-shaped polyester toughening agent undergo transesterification with the polycarbonate chain ends, forming a chemically bonded block copolymer structure. The multi-arm terminals of the star-shaped topology can simultaneously connect with multiple polycarbonate chain segments, forming a physical cross-linking network in the matrix. When the material is subjected to external impact, this physical cross-linking network can effectively prevent crack propagation through the stress dispersion and energy dissipation mechanism of the multi-arm structure. Simultaneously, the polycaprolactone chain segments, acting as flexible spacer units, impart excellent toughness to the material.

[0011] (2) This invention achieves the optimal compatibility and reactivity balance between the toughening agent and the polycarbonate matrix by precisely controlling the arm length of the star-shaped polycaprolactone. When the arm length of the star-shaped polyester is moderate (number average molecular weight 4600-5100), the polycaprolactone segments have sufficient mobility to dissipate impact energy and maintain good compatibility with the polycarbonate matrix, thus achieving uniform dispersion; if the arm length is too short, the segment movement is restricted, and the toughening effect is limited; if the arm length is too long, the steric hindrance increases, the compatibility with the matrix decreases, and phase separation easily occurs.

[0012] (3) Through the synergistic effect of the above technical solutions, the modified isosorbide polycarbonate prepared by this invention has excellent toughness and transparency, and the elongation at break of the product reaches 163-171% and the notched impact strength reaches 18.3-20.2 kJ / m. 2 The light transmittance remains at 86.1-89.2%. This indicates that the star-shaped polyester toughening agent of the present invention, through multi-arm chemical bonding and uniform dispersion, significantly improves the toughness and impact resistance of the material without sacrificing its transparency. Detailed Implementation

[0013] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described.

[0014] Example 1 Preparation of isosorbide polycarbonate modified with a bio-based toughening agent: (1) Synthetic star-shaped polyester toughening agent 1.36 g of pentaerythritol was dried under vacuum at 110 °C for 1 hour. Under nitrogen protection, the dried pentaerythritol was mixed with 45.6 g of ε-caprolactone and 0.05 g of stannous octoate. The mixture was heated to 130 °C and stirred under nitrogen atmosphere for 12 hours. After the reaction was completed, the mixture was cooled to 40 °C. 50 mL of dichloromethane was added to completely dissolve the product. The solution was then slowly added dropwise to 310 mL of cold methanol with stirring. A white precipitate was precipitated. The precipitate was collected by filtration and washed with cold methanol. The above dissolution-precipitation operation was repeated once. The final product was dried under vacuum at 40 °C to constant weight to obtain the star-shaped polyester toughening agent. The temperature of the cold methanol is 2°C; The number-average molecular weight of the obtained star-shaped polyester toughening agent was 4880.

[0015] (2) Synthesis of isosorbide-decanediol copolycarbonate 192g of isosorbide, 26g of 1,10-decanediol, 320g of diphenyl carbonate, and 0.47g of lithium acetylacetonate were mixed. The air in the reactor was replaced twice with nitrogen. The temperature was raised to 180°C, and the mixture was stirred until the materials were completely melted and mixed. Then the temperature was raised to 200°C, and the distilled phenol was collected. At the same time, the pressure was gradually reduced to 20 kPa. The reaction was carried out at this temperature and pressure for 1.5 hours. Then the temperature was raised to 220°C, and the pressure was reduced to below 100 Pa. The reaction was continued for 2 hours. After the reaction was completed, the heating was stopped, nitrogen was introduced to release the vacuum, and the polymer was poured out while hot. After cooling, a pale yellow solid isosorbide-decanediol copolycarbonate was obtained.

[0016] (3) Reactive blending 200g of isosorbide-decanediol copolycarbonate and 16g of star-shaped polyester toughening agent were vacuum dried at 90℃ for 4 hours. The two materials were thoroughly shaken and mixed in a sealed container. The mixture was heated to 205℃ and melt-kneaded under nitrogen protection for 7 minutes. After kneading, heating was stopped, the blend was taken out, cooled to room temperature, and pelletized to obtain modified isosorbide polycarbonate.

[0017] Example 2 Preparation of isosorbide polycarbonate modified with a bio-based toughening agent: (1) Synthetic star-shaped polyester toughening agent 1.36 g of pentaerythritol was dried under vacuum at 105 °C for 1.2 hours. Under nitrogen protection, the dried pentaerythritol was mixed with 43.3 g of ε-caprolactone and 0.04 g of stannous octoate. The mixture was heated to 125 °C and stirred under nitrogen atmosphere for 14 hours. After the reaction was completed, the mixture was cooled to 38 °C, and 46 mL of dichloromethane was added to completely dissolve the product. The solution was then slowly added dropwise to 275 mL of cold methanol with stirring, resulting in a white precipitate. The precipitate was collected by filtration and washed with cold methanol. The above dissolution-precipitation operation was repeated once. The final product was dried under vacuum at 38 °C to constant weight to obtain the star-shaped polyester toughening agent.

[0018] The temperature of the cold methanol is 0°C; The number-average molecular weight of the obtained star-shaped polyester toughening agent was 4640.

[0019] (2) Synthesis of isosorbide-decanediol copolycarbonate 177g isosorbide, 21g 1,10-decanediol, 320g diphenyl carbonate, and 0.32g lithium acetylacetonate were mixed. The air in the reactor was replaced twice with nitrogen. The temperature was raised to 175°C, and the mixture was stirred until the materials were completely melted and mixed. The temperature was then raised to 195°C, and the distilled phenol was collected. At the same time, the pressure was gradually reduced to 19 kPa. The reaction was carried out at this temperature and pressure for 1.6 hours. Then the temperature was raised to 215°C, and the pressure was reduced to below 100 Pa. The reaction was continued for 2.2 hours. After the reaction was completed, heating was stopped, nitrogen was introduced to release the vacuum, and the polymer was poured out while hot. After cooling, a pale yellow solid isosorbide-decanediol copolycarbonate was obtained.

[0020] (3) Reactive blending 200g of isosorbide-decanediol copolycarbonate and 20g of star-shaped polyester toughening agent were vacuum dried at 85℃ for 4.5 hours. The two materials were thoroughly shaken and mixed in a sealed container. The mixture was heated to 200℃ and melt-mixed under nitrogen protection for 7.5 minutes. After mixing, heating was stopped, the blend was taken out, cooled to room temperature, and pelletized to obtain modified isosorbide polycarbonate.

[0021] Example 3 Preparation of isosorbide polycarbonate modified with a bio-based toughening agent: (1) Synthetic star-shaped polyester toughening agent 1.36 g of pentaerythritol was dried under vacuum at 115 °C for 0.8 hours. Under nitrogen protection, the dried pentaerythritol was mixed with 47.9 g of ε-caprolactone and 0.057 g of stannous octoate. The mixture was heated to 135 °C and stirred under nitrogen atmosphere for 10 hours. After the reaction was completed, the mixture was cooled to 42 °C, and 56 mL of dichloromethane was added to completely dissolve the product. The solution was then slowly added dropwise to 345 mL of cold methanol with stirring, resulting in a white precipitate. The precipitate was collected by filtration and washed with cold methanol. The above dissolution-precipitation operation was repeated once. The final product was dried under vacuum at 42 °C to constant weight to obtain the star-shaped polyester toughening agent.

[0022] The temperature of the cold methanol is 5°C; The number-average molecular weight of the obtained star-shaped polyester toughening agent was 5120.

[0023] (2) Synthesis of isosorbide-decanediol copolycarbonate 207g isosorbide, 31g 1,10-decanediol, 320g diphenyl carbonate, and 0.63g lithium acetylacetonate were mixed. The air in the reactor was replaced with nitrogen three times. The temperature was raised to 185°C, and the mixture was stirred until the materials were completely melted and mixed. Then the temperature was raised to 205°C, and the distilled phenol was collected. At the same time, the pressure was gradually reduced to 21 kPa. The reaction was carried out at this temperature and pressure for 1.4 hours. Then the temperature was raised to 225°C, and the pressure was reduced to below 100 Pa. The reaction was continued for 1.8 hours. After the reaction was completed, the heating was stopped, nitrogen was introduced to release the vacuum, and the polymer was poured out while hot. After cooling, a pale yellow solid isosorbide-decanediol copolycarbonate was obtained.

[0024] (3) Reactive blending 200g of isosorbide-decanediol copolycarbonate and 24g of star-shaped polyester toughening agent were vacuum dried at 95℃ for 3.5 hours. The two materials were thoroughly shaken and mixed in a sealed container. The mixture was heated to 210℃ and melt-blended under nitrogen protection for 6.5 minutes. After blending, heating was stopped, the blend was removed, cooled to room temperature, and pelletized to obtain modified isosorbide polycarbonate.

[0025] Comparative Example 1 Comparative Example 1 uses the preparation method of modified isosorbide polycarbonate described in Example 1, except that the step of synthesizing star-shaped polyester toughening agent is omitted in the pretreatment step, and linear polycaprolactone (molecular weight of 5000) is used instead of star-shaped polyester in the reactive blending step, while the other steps are the same.

[0026] Comparative Example 2 Comparative Example 2 uses the preparation method of modified isosorbide polycarbonate described in Example 1, except that the amount of ε-caprolactone is reduced to 18.4g in the step of synthesizing the star-shaped polyester toughening agent, while the other steps are the same.

[0027] The number-average molecular weight of the star-shaped polyester toughening agent obtained in the synthesis step is 1980.

[0028] Comparative Example 3 Comparative Example 3 uses the preparation method of modified isosorbide polycarbonate described in Example 1, except that in the step of synthesizing star-shaped polyester toughening agent, the amount of ε-caprolactone is reduced to 91.2g, and the other steps are the same.

[0029] The number-average molecular weight of the star-shaped polyester toughening agent obtained in the synthesis step is 9750.

[0030] Performance testing The modified isosorbide polycarbonates prepared by the methods of Examples 1-3 and Comparative Examples 1-3 were tested according to ISO 527-2 (Test Method for Tensile Properties of Plastics), ISO 180:2023 (Determination of Cantilever Beam Impact Strength of Plastics), and ASTM D1003-2013 (Standard Test Method for Opacity and Transmittance of Transparent Plastics). The test results are shown in Table 1. The test results are shown in Table 1.

[0031] Table 1

[0032] As shown in Table 1, the modified isosorbide polycarbonate prepared by the methods in Examples 1-3 has an elongation at break of 163-171% and a notched impact strength of 18.3-20.2 kJ / m. 2 The light transmittance is 86.1-89.2%, indicating that the synergistic effect of the four-arm star-shaped polyester toughening agent and the isosorbide-decanediol copolymer system can significantly improve the toughness of the material while effectively maintaining its excellent transparency.

[0033] The linear polycaprolactone used in Comparative Example 1 lacks a multi-arm spatial structure and has a small number of terminal hydroxyl groups. Its reactivity with isosorbide-decanediol copolycarbonate is low, and it cannot form an effective block copolymer. As a result, its toughness and transparency are significantly lower than those of the examples.

[0034] In Comparative Example 2, the amount of ε-caprolactone used in the synthesis of the star-shaped polyester toughening agent was reduced to 18.4g, resulting in a star-shaped polyester with a number average molecular weight of 1980. The arm length was too short, and it could not form an effective toughening structure after reacting with isosorbide-decanediol copolycarbonate. Therefore, the toughness was lower than that of the Example, but higher than that of Comparative Example 1; the light transmittance was 87.3%, which was close to that of the Example.

[0035] In Comparative Example 3, the amount of ε-caprolactone was increased to 91.2 g when synthesizing the star-shaped polyester toughening agent, resulting in a star-shaped polyester with a number average molecular weight of 9750. The arm length was too long, the steric hindrance was significantly increased, the compatibility with the isosorbide-decanediol copolycarbonate matrix was greatly reduced, the reactive blending efficiency was also extremely low, and the phase separation was severe. Therefore, the toughness was significantly reduced, lower than that of Example and Comparative Example 2; the light transmittance was 69.8%, which was significantly reduced.

[0036] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing isosorbide polycarbonate modified with a bio-based toughening agent, characterized in that, The method includes the following steps: synthesizing a star-shaped polyester toughening agent, synthesizing isosorbide-decanediol copolycarbonate, and reactive blending; The method for synthesizing the star-shaped polyester toughening agent is as follows: Pentaerythritol is vacuum dried at 105-115℃ for 0.8-1.2 hours. Under nitrogen protection, the dried pentaerythritol is mixed with ε-caprolactone and stannous octoate, and the mixture is heated to 125-135℃ and stirred under nitrogen atmosphere for 10-14 hours. After the reaction is completed, the mixture is cooled to 38-42℃, and dichloromethane is added to completely dissolve the product. The solution is then slowly added dropwise to cold methanol while stirring, resulting in the precipitation of a white precipitate. The precipitate is collected by filtration and washed with cold methanol. The above dissolution-precipitation operation is repeated once. The final product is vacuum dried at 38-42℃ to constant weight to obtain the star-shaped polyester toughening agent. The reactive blending method is as follows: isosorbide-decanediol copolycarbonate and star-shaped polyester toughening agent are vacuum dried at 85-95℃ for 3.5-4.5 hours. The two materials are thoroughly shaken and mixed in a sealed container. The mixture is heated to 200-210℃ and melt-blended under nitrogen protection for 6.5-7.5 minutes. After blending, heating is stopped, the blend is taken out, cooled to room temperature, and pelletized to obtain modified isosorbide polycarbonate.

2. The method for preparing a bio-based toughening agent modified isosorbide polycarbonate according to claim 1, characterized in that, In the step of synthesizing the star-shaped polyester toughening agent The molar ratio of pentaerythritol, ε-caprolactone and stannous octoate is 10:380-420:0.1-0.

14.

3. The method for preparing a bio-based toughening agent modified isosorbide polycarbonate according to claim 1, characterized in that, In the step of synthesizing the star-shaped polyester toughening agent The temperature of the cold methanol is 0-5℃; The amounts of dichloromethane and cold methanol used are 45-55 times and 160-200 times the mass of pentaerythritol, respectively.

4. The method for preparing a bio-based toughening agent modified isosorbide polycarbonate according to claim 1, characterized in that, In the step of synthesizing the star-shaped polyester toughening agent, the number average molecular weight of the star-shaped polyester toughening agent is 4600-5100.

5. The method for preparing a bio-based toughening agent modified isosorbide polycarbonate according to claim 1, characterized in that, The method for synthesizing the isosorbide-decanediol copolycarbonate is as follows: isosorbide, 1,10-decanediol, diphenyl carbonate, and lithium acetylacetonate are mixed, and the air in the reactor is replaced with nitrogen 2-3 times. The temperature is raised to 175-185°C, and the mixture is stirred to completely melt and mix the materials. Then the temperature is raised to 195-205°C, and the distilled phenol is collected. At the same time, the pressure is gradually reduced to 19-21 kPa. The reaction is carried out at this temperature and pressure for 1.4-1.6 hours. Then the temperature is raised to 215-225°C, and the pressure is reduced to below 100 Pa. The reaction is continued for 1.8-2.2 hours. After the reaction is completed, heating is stopped, nitrogen is introduced to release the vacuum, and the polymer is poured out while hot. After cooling, a pale yellow solid isosorbide-decanediol copolycarbonate is obtained.

6. The method for preparing a bio-based toughening agent modified isosorbide polycarbonate according to claim 5, characterized in that, In the synthesis step of the isosorbide-decanediol copolycarbonate, The molar ratio of isosorbide, 1,10-decanediol, diphenyl carbonate, and lithium acetylacetonate is 0.81-0.95:0.08-0.12:1:0.002-0.

004.

7. The method for preparing a bio-based toughening agent modified isosorbide polycarbonate according to claim 1, characterized in that, In the reactive blending step, the mass ratio of isosorbide-decanediol copolycarbonate to star-shaped polyester toughening agent is 100:8-12.

8. Bio-based toughening agent modified isosorbide polycarbonate prepared by the method according to any one of claims 1-7.

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