A biobased polycarbonate copolymer and a method of making the same

Abstract

The application discloses a kind of bio-based polycarbonate copolymer and preparation method thereof, belong to new material technical field.The bio-based polycarbonate copolymer is prepared by isosorbide and its isomer, crystallizable oligomer diol, amide diol, carbonic acid diester and catalyst through ester exchange process and polycondensation process.The application successfully solves the problem that the bio-based polycarbonate is poor in plasticity and toughness, and the strength, toughness and heat resistance cannot be balancedly realized.Finally, high-strength, high-toughness and high-heat-resistance bio-based polycarbonate polymer is successfully prepared by copolymerizing isosorbide, amide diol and crystallizable oligomer diol.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, and in particular relates to a bio-based polycarbonate copolymer and its preparation method. Background Technology

[0002] Bisphenol A-type polycarbonate (BPA-PC) possesses excellent overall properties and is therefore widely used in electronics, food packaging, building materials, and medical devices. However, research indicates that bisphenol A, the main raw material for BPA-PC, exhibits slow toxicity and estrogenic effects, potentially harming human health. Therefore, finding a bio-based alternative to bisphenol A to prepare high-performance, green, and non-toxic polycarbonate is of great significance.

[0003] Isosorbide is a rigid bicyclic diol derived from bio-based sugars, with a similar chemical structure to bisphenol A (BPA), and is considered the most promising bio-based raw material to replace BPA in the preparation of polycarbonate. However, due to the large number of rigid isosorbide groups in the main chain structure of isosorbide-based polycarbonate, its glass transition temperature is high, resulting in poor plasticity and difficulty in processing. Therefore, it is essential to modify isosorbide-based polycarbonate to improve its plasticity and processability.

[0004] Currently, most chemical modifications of isosorbide-based polycarbonate involve copolymerizing it with flexible small-molecule diols to prepare isosorbide-based polycarbonate polymers. As the content of flexible diols increases, the plasticity and toughness increase, but this is inevitably accompanied by a significant decrease in strength and glass transition temperature, which greatly limits its application in the field of engineering plastics. For example, the paper "Green and Efficient Synthesis of Biobased Polycarbonates with Tunable Performance via Functionalized Ionic Liquid Catalysts Enhanced by Cation–π Interactions" (https: / / doi.org / 10.1021 / acs.iecr.4c00480) prepared isosorbide-based polycarbonate copolymers by copolymerizing isosorbide with 1,10-decanediol. The incorporation of the soft comonomer improved the ductility and processability of isosorbide-based polycarbonate, increasing the elongation at break from 34% to 358%, and decreasing its tensile strength from 63.6 MPa to 36.7 MPa, but decreasing its glass transition temperature from 99 °C to 43 °C. For example, the paper "Synthesis of Thermal-Resistant Polyester-Polycarbonate with Fully Rigid Structure from Biobased Isosorbide" (https: / / doi.org / 10.1021 / acs.macromol.4c00647) prepared isosorbide-based polyester-polycarbonate copolymers via melt transesterification using isosorbide, dimethyl terephthalate, 1,4-cyclohexanediethanol, and dimethyl carbonate. By adjusting the ratio of isosorbide to 1,4-cyclohexanediethanol, the flexibility of the isosorbide-based polycarbonate was successfully increased, achieving an elongation at break of 136%. However, its glass transition temperature decreased to 76 °C, and the significant increase in fracture strain was accompanied by a sharp decrease in glass transition temperature. Therefore, the addition of flexible small molecules is not conducive to the preparation of a bio-based polycarbonate copolymer with high strength, high toughness, high transparency, and a high glass transition temperature.

[0005] Patent CN 105237755 A discloses a copolycarbonate with low water absorption and excellent heat resistance, low temperature properties and surface hardness. However, this invention finds that its related properties, such as glass transition temperature, light transmittance and pencil hardness, still have room for improvement. Summary of the Invention

[0006] Technical issues When preparing polycarbonate using isosorbide, issues arise regarding plasticity, toughness, strength, and glass transition temperature. These four factors cannot be well coordinated to achieve an excellent result in all four aspects. Therefore, there is a need to provide a method for preparing a bio-based polycarbonate copolymer with high strength, high toughness, high transparency, and a high glass transition temperature.

[0007] Technical content To address the aforementioned problems in existing technologies, this invention provides a high-performance bio-based polycarbonate copolymer and its preparation method. This invention prepares a bio-based polycarbonate copolymer by copolymerizing isosorbide with an amide diol and a crystallizable oligomeric diol. This copolymer not only possesses high strength, high toughness, and high transparency, but also exhibits high heat resistance; it is a highly promising bio-based engineering plastic.

[0008] The first objective of this invention is to provide a high-performance bio-based polycarbonate copolymer, wherein the bio-based polycarbonate copolymer has a tensile strength of not less than 70 MPa, an elongation at break of not less than 70%, a light transmittance of not less than 90%, a glass transition temperature of not less than 130°C, a pencil hardness of not less than 2H, and a relative weight-average molecular weight of 6 × 10⁻⁶. 4 -2×10 5 between.

[0009] Furthermore, the bio-based polycarbonate copolymer molecular chain is composed of the following structural units: -ORCOO-, -OR1COO- and -OR2COO- groups.

[0010] Furthermore, R is isohexitol C6H8O2.

[0011] Furthermore, R1 is (C6H 10 O2) x OR3 or (C6H) 10 O2) x ·R3, x=4~8.

[0012] Furthermore, R2 is C4H 10 O2(N)COR4.

[0013] Furthermore, R3 and R4 are selected from alkanes containing 2-15 carbon atoms.

[0014] Furthermore, the ratio of -ORCOO- to -OR1COO- groups is 1:0.03~0.07.

[0015] Furthermore, the ratio of -ORCOO- to -OR2COO- groups is 1:0.01~0.04.

[0016] A second objective of this invention is to provide applications of the aforementioned high-performance bio-based polycarbonate copolymer in the fields of electronics, food packaging, building materials, containers, transportation, engineering plastics, or medical devices.

[0017] A third objective of this invention is to provide a method for preparing a high-performance bio-based polycarbonate copolymer, the method comprising the following steps: (1) Under a protective atmosphere, isosorbide, crystallizable oligomeric diol, amide diol and carbonate diester are heated and melted, and then a catalyst is added to carry out the reaction; (2) Under low vacuum conditions, the reaction temperature is raised to 200-280°C and the reaction time is maintained for 0.2h-5h to obtain high-performance isosorbide-based polyester-polycarbonate copolymer.

[0018] Furthermore, the protective gas in step (1) includes nitrogen and / or an inert gas.

[0019] Furthermore, in step (1), isosorbide can be replaced by its isomer with the molecular formula C6H. 10 O4.

[0020] Furthermore, the crystallizable oligomeric diol in step (1) is a homopolymer diol of 2-oxetane-heptane ketone.

[0021] Furthermore, the crystallizable oligomeric diol in step (1) is specifically polycaprolactone diol.

[0022] Furthermore, the molecular weight of the crystallizable oligomeric diol in step (1) is 500~800.

[0023] Furthermore, in step (1), the amide diol is selected from at least one of N,N-bis(2-hydroxyethyl)acetamide, N,N-bis(2-hydroxyethyl)propionamide, N,N-bis(2-hydroxyethyl)butyramide, N,N-bis(2-hydroxyethyl)pentanamide, N,N-bis(2-hydroxyethyl)hexamamide, N,N-bis(2-hydroxyethyl)heptamide and N,N-bis(2-hydroxyethyl)octamide.

[0024] Furthermore, the preparation process of the amide diol is as follows: diethanolamine and fatty acid methyl ester are stirred under a nitrogen atmosphere, a catalyst is added to carry out the reaction, and then the reaction product is extracted and purified to obtain the amide diol.

[0025] In one embodiment of the present invention, the molar ratio of diethanolamine to fatty acid methyl ester is 1:0.8~1.2.

[0026] In one embodiment of the present invention, the fatty acid methyl ester includes any one of methyl formate, methyl acetate, methyl propionate, methyl butyrate, methyl valerate, methyl hexanoate, and methyl heptanoate.

[0027] In one embodiment of the present invention, the catalyst is sodium methoxide.

[0028] In one embodiment of the present invention, the molar ratio of diethanolamine to catalyst is 1:0.005~0.01.

[0029] In one embodiment of the present invention, the reaction temperature is 20~25°C and the reaction time is 20~30 hours.

[0030] In one embodiment of the present invention, the extraction and purification process includes washing with saturated brine, drying with anhydrous magnesium sulfate, and rotary evaporation.

[0031] Furthermore, in step (1), the carbonate diester is selected from one of diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate and dibutyl carbonate.

[0032] Furthermore, the molar ratio of isosorbide to crystallizable oligomeric diol is 1:0.03~0.1.

[0033] Furthermore, the molar ratio of isosorbide to amide diol is 1:0.01~0.05.

[0034] Furthermore, the molar ratio of isosorbide to carbonate diester is 1:1~10.

[0035] Preferably, the molar ratio of isosorbide to diester is 1:1~5.

[0036] Specifically, the molar ratio of isosorbide to diester is 1:1~2.

[0037] Furthermore, the heating and melting temperature in step (1) is 90~150℃.

[0038] Furthermore, the catalyst mentioned in step (1) is at least one of a metal catalyst, a basic catalyst, and an ionic liquid catalyst.

[0039] Furthermore, the metal catalyst is one of lithium acetylacetonate, lithium lactate, or cesium carbonate.

[0040] Furthermore, the alkaline catalyst is one of 1,5,7-triazabicyclo[4.4.0]decene-5-ene and 4-dimethylaminopyridine.

[0041] Furthermore, the ionic liquid catalyst is one of 1-ethyl-3-methylimidazolium lactate and 1-butyl-3-methylimidazolium lactate.

[0042] Preferably, the catalyst in step (1) is selected from one of 1-butyl-3-methylimidazolium lactate, lithium acetylacetonate, lithium lactate and 1-ethyl-3-methylimidazolium lactate.

[0043] Furthermore, in step (1), the molar amount of catalyst added is 0.005-0.01% of the molar amount of diester.

[0044] Furthermore, the reaction time in step (1) is 1 to 5 hours.

[0045] Furthermore, the low vacuum condition mentioned in step (2) refers to a vacuum degree of less than 100 Pa.

[0046] Furthermore, the low vacuum condition mentioned in step (2) refers to a vacuum level of 10~100 Pa.

[0047] The beneficial effects of this invention are as follows: 1. Compared with the prior art, the present invention introduces amide diol, which can increase the polarity of the resulting polymer molecules, effectively enhance the strength and heat resistance of the polymer, and give the polymer better flexibility.

[0048] 2. Compared with the prior art, the present invention selects crystallizable oligomeric diol (polycaprolactone diol, Mn=500~800). Compared with small molecule diols, this oligomeric diol has longer chain segments and higher molecular weight, thus making it easier to prepare polycarbonate copolymers with higher molecular weight. In addition, the crystallizable oligomeric diol has highly polar ester groups, which can impart higher tensile strength and glass transition temperature to the main chain. Furthermore, the longer alkane segments in the crystallizable oligomeric diol can effectively increase the elongation at break and toughness of the bio-based polycarbonate copolymer.

[0049] 3. This invention obtains a bio-based polycarbonate copolymer with high tensile strength, excellent fracture resistance and high glass transition temperature by effectively controlling the molecular weight and molar amount of crystallizable oligomeric diols. Its tensile strength is 70-80 MPa, elongation is 70-100% and glass transition temperature is 130-140°C. Detailed Implementation

[0050] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The raw materials used in the embodiments of the present invention are all commercially available unless otherwise specified; wherein, isosorbide has a purity greater than 98%, diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and dibutyl carbonate have a purity of 99%, the homopolymer diol of 2-oxetane heptanone (PCL diol) has a purity of 99%, and lithium acetylacetonate, lithium lactate, cesium carbonate, 1,5,7-triazabicyclo[4.4.0]decen-5-ene, 4-dimethylaminopyridine, 1-ethyl-3-methylimidazolium lactate, and 1-butyl-3-methylimidazolium lactate all have a purity of 99%.

[0051] N,N-bis(2-hydroxyethyl)acetamide, N,N-bis(2-hydroxyethyl)propionamide, N,N-bis(2-hydroxyethyl)butyramide, N,N-bis(2-hydroxyethyl)pentanamide, N,N-bis(2-hydroxyethyl)hexamamide, N,N-bis(2-hydroxyethyl)heptanamide, and N,N-bis(2-hydroxyethyl)octanamide were synthesized, and the specific preparation process is as follows: Taking N,N-bis(2-hydroxyethyl)acetamide as an example, 2.1 g of diethanolamine and 1.213 g of methyl formate were stirred at room temperature under a nitrogen atmosphere, and 6 mg of sodium methoxide was added as a catalyst. The reaction was continued for 24 h. The reaction product was then dissolved in an appropriate amount of dichloromethane, washed three times with saturated brine, dried with anhydrous magnesium sulfate, and finally obtained by rotary evaporation.

[0052] Similarly, N,N-bis(2-hydroxyethyl)propionamide, N,N-bis(2-hydroxyethyl)butyramide, N,N-bis(2-hydroxyethyl)pentanamide, N,N-bis(2-hydroxyethyl)hexamamide, N,N-bis(2-hydroxyethyl)heptanamide, and N,N-bis(2-hydroxyethyl)octanamide were all prepared by reacting diethanolamine with equimolar amounts of methyl acetate, methyl propionate, methyl butyrate, methyl valerate, methyl hexanoate, and methyl heptanoate, respectively, following the preparation process described above.

[0053] Testing process Gel permeation chromatography: Dissolve 5 mg of sample in 2 mL of spectral grade N,N-dimethylformamide, filter using a 0.22 μm organic filter membrane, and test the flow rate using an Agilent 1260 GPC at 1 mL / min. N,N-dimethylformamide was used as the mobile phase, and polystyrene was used as the standard.

[0054] Mechanical properties: The samples were cut into dumbbell-shaped strips with a width of 4 mm, a thickness of 0.5 mm, and a length of 18 mm. An Instron 5967X bi-column benchtop testing system was used, and the tensile rate was 10 mm / min at room temperature. Five strips were taken for each sample, the average value was calculated, and the error was calculated.

[0055] Glass transition temperature: The glass transition temperature of the sample was tested using a Mettler DSC 3. 10 mg of sample was placed in an aluminum crucible. First, the temperature was increased from 30 °C to 200 °C at a rate of 30 °C / min and held for 1 min. Then, the temperature was decreased from 200 °C to -20 °C at a rate of 30 °C / min and held for 1 min. Finally, the temperature was increased from 30 °C to 200 °C at a rate of 10 °C / min. The inflection point was taken as the glass transition temperature.

[0056] Transmittance: Tested using a Shimadzu UV-3600 plus from 400-800 nm. The sample thickness was 0.2 mm, and the transmittance data was taken from 550 nm.

[0057] Pencil hardness: Tested using a Shanghai Pushen BY pencil hardness tester according to national standard GB / T 6739-2006.

[0058] Example 1 11.035 g isosorbide, 17.31 g diphenyl carbonate, 2.12 g PCL glycol (Mn=530) and 0.294 g N,N-bis(2-hydroxyethyl)acetamide were added to a three-necked flask and heated at 135°C under a nitrogen atmosphere. After the raw materials melted, 1 mg 1-butyl-3-methylimidazolium lactate was added, and the mixture was mechanically stirred for 4 h to carry out the transesterification process. Then, the nitrogen atmosphere was turned off, the vacuum was adjusted to 80 Pa, and the temperature was continuously raised to 250°C to carry out the polycondensation process. The reaction was stopped after 0.5 h to obtain the copolymer with a yield of 98% and a weight average molecular weight of 112,500.

[0059] The mechanical and thermal properties of the copolymer are shown in Table 1.

[0060] Example 2 Similar to Example 1, 1-butyl-3-methylimidazolium lactate was replaced with an equimolar amount of lithium acetylacetonate, while other conditions remained unchanged, to obtain a copolymer with a yield of 94% and a weight-average molecular weight of 96,400.

[0061] Example 3 Similar to Example 1, 1-butyl-3-methylimidazolium lactate was replaced with an equimolar amount of lithium lactate, while other conditions remained unchanged, to obtain a copolymer with a yield of 92% and a weight-average molecular weight of 89,600.

[0062] Example 4 Similar to Example 1, 1-butyl-3-methylimidazolium lactate was replaced with an equimolar amount of cesium carbonate, while other conditions remained unchanged, to obtain a copolymer with a yield of 89% and a weight-average molecular weight of 85,300.

[0063] Example 5 Same as in Example 1, but 1-butyl-3-methylimidazolium lactate was replaced with an equimolar amount of 1,5,7-triazabicyclo[4.4.0]decene-5-ene, with other conditions remaining unchanged, to obtain a copolymer with a yield of 90% and a weight-average molecular weight of 75,300.

[0064] Example 6 Similar to Example 1, 1-butyl-3-methylimidazolium lactate was replaced with an equimolar amount of 4-dimethylaminopyridine, and other conditions remained unchanged, to obtain a copolymer with a yield of 91% and a weight-average molecular weight of 64,200.

[0065] Example 7 Similar to Example 1, 1-butyl-3-methylimidazolium lactate was replaced with an equimolar amount of 1-ethyl-3-methylimidazolium lactate, with other conditions remaining unchanged, to obtain a copolymer with a yield of 97% and a weight-average molecular weight of 103,700.

[0066] Example 8 Similar to Example 1, the temperature during the polycondensation process was adjusted to 240°C, while other conditions remained unchanged, to obtain a copolymer with a yield of 96% and a weight-average molecular weight of 106,700.

[0067] Example 9 Same as in Example 1, but with the raw materials replaced by 11.035 g isosorbide, 17.31 g diphenyl carbonate, 2.12 g PCL diol (Mn=530) and 0.322 g N,N-bis(2-hydroxyethyl)propionamide, and other conditions unchanged, the yield was 98% and the weight average molecular weight of the product was 125,500.

[0068] Example 10 Same as in Example 1, but with the raw materials replaced by 11.035 g isosorbide, 17.31 g diphenyl carbonate, 2.12 g PCL diol (Mn=530) and 0.351 g N,N-bis(2-hydroxyethyl)butyramide, and other conditions unchanged, a copolymer was obtained with a yield of 98% and a weight-average molecular weight of 113200.

[0069] Example 11 Same as in Example 1, but the raw materials were replaced with 11.035 g isosorbide, 17.31 g diphenyl carbonate, 2.12 g PCL diol (Mn=530) and 0.519 g N,N-bis(2-hydroxyethyl)decanoamide, and the catalyst was replaced with an equimolar amount of lithium acetylacetone. Other conditions remained unchanged, and a copolymer was obtained with a yield of 94% and a weight-average molecular weight of 96,500.

[0070] Comparative Example 1 11.035 g isosorbide, 17.31 g diphenyl carbonate and 2.4 g PCL glycol (Mn=400) were added to a three-necked flask and melted at 135°C under N2 atmosphere. Then 1 mg 1-butyl-3-methylimidazolium lactate was added and mechanically stirred for 4 h. The nitrogen atmosphere was then turned off and the vacuum was adjusted to 80 Pa. The temperature was then continuously raised to 250°C and the reaction was stopped after 0.5 h to obtain the copolymer with a yield of 96% and a weight average molecular weight of 104,600.

[0071] Comparative Example 2 11.035 g isosorbide, 17.31 g diphenyl carbonate and 3.18 g PCL glycol (Mn=530) were added to a three-necked flask and melted at 135°C under a N2 atmosphere. Then 1 mg 1-butyl-3-methylimidazolium lactate was added and mechanically stirred for 4 h. The nitrogen atmosphere was then turned off and the vacuum was adjusted to 80 Pa. The temperature was then continuously raised to 250°C and the reaction was stopped after 0.5 h to obtain the copolymer with a yield of 97% and a weight average molecular weight of 116,600.

[0072] Comparative Example 3 Similar to Comparative Example 1, the raw materials were replaced with 11.035 g isosorbide, 17.31 g diphenyl carbonate and 4.98 g PCL glycol (Mn=830), and other conditions remained unchanged. A copolymer was obtained with a yield of 96% and a weight-average molecular weight of 119,900.

[0073] Table 1. Performance Comparison of Examples and Comparative Examples

[0074] As can be seen from the data in Table 1, the copolymers prepared in the embodiments of the present invention generally exhibit significantly higher glass transition temperature, light transmittance, and pencil hardness compared to the copolymers in the comparative examples. This indicates that the introduction of amide diols can increase the polarity of polymer molecules, effectively enhancing the strength and heat resistance of the polymer, achieving higher glass transition temperatures and pencil hardness. Furthermore, the alkane chains on the side chains of the amide diols can effectively improve the flexibility of the polymer. Simultaneously, the selection of polycaprolactone diol with a molecular weight of 500-800 is also crucial for achieving the improved copolymer performance in this invention.

[0075] Furthermore, in the data comparison of Examples 1 to 7, it can be found that the elongation at break of the copolymers prepared under different catalysts is different, among which 1-ethyl-3-methylimidazolium lactate, lithium acetylacetonate and lithium lactate are more effective.

[0076] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A high-performance bio-based polycarbonate copolymer, characterized in that, Its molecular chain contains the following structural units: -ORCOO-, -OR1COO- and -OR2COO- groups; Where R is C6H8O2, and R1 is [(C6H8O2)] 10 O2) x ·OC4H8], R2 is [C4H8(N)COR4], R4 is selected from at least one alkane containing 2-15 C atoms, x=4~8; The ratio of -ORCOO-, -OR1COO-, and -OR2COO- groups is 1 : 0.03~0.07 : 0.01~0.04; The method for preparing the bio-based polycarbonate copolymer includes the following steps: (1) Under a protective atmosphere, isosorbide, crystallizable oligomeric diol, amide diol and carbonate diester are heated and melted, and then a catalyst is added to carry out the reaction; The oligomeric diol is polycaprolactone diol with a molecular weight of 500-800. The amide diol is selected from at least one of N,N-bis(2-hydroxyethyl)propionamide, N,N-bis(2-hydroxyethyl)butyramide, N,N-bis(2-hydroxyethyl)pentanamide, N,N-bis(2-hydroxyethyl)hexamamide, N,N-bis(2-hydroxyethyl)heptamide and N,N-bis(2-hydroxyethyl)octamide; The carbonate diester is selected from one of diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and dibutyl carbonate; The molar ratio of isosorbide to crystallizable oligomeric diol is 1:0.03~0.1; the molar ratio of isosorbide to amide diol is 1:0.01~0.05; the molar ratio of isosorbide to carbonate diester is 1:1~10. The catalyst is selected from one of lithium acetylacetonate, lithium lactate, cesium carbonate, 1,5,7-triazabicyclo[4.4.0]decen-5-ene and 4-dimethylaminopyridine, 1-ethyl-3-methylimidazolium lactate and 1-butyl-3-methylimidazolium lactate; the molar amount of catalyst added is 0.005-0.01% of the molar amount of diester. (2) Under low vacuum conditions, the reaction temperature is raised to 200-280°C and the reaction time is maintained for 0.2h-5h to obtain high-performance isosorbide-based polyester-polycarbonate copolymer.

2. The bio-based polycarbonate copolymer according to claim 1, characterized in that, The heating and melting temperature in step (1) is 90~150℃.

3. The bio-based polycarbonate copolymer according to claim 1, characterized in that, In step (1), the catalyst is selected from one of 1-butyl-3-methylimidazolium lactate, lithium acetylacetonate, lithium lactate and 1-ethyl-3-methylimidazolium lactate.

4. The bio-based polycarbonate copolymer according to claim 1, characterized in that, The reaction time in step (1) is 1 to 5 hours.

5. The bio-based polycarbonate copolymer according to claim 1, characterized in that, The low vacuum condition mentioned in step (2) refers to a vacuum degree of less than 100 Pa.

6. The application of the bio-based polycarbonate copolymer according to claim 1 in the fields of electronics, food packaging, building materials, containers, transportation vehicles, engineering plastics or medical devices.

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