High performance isosorbide-based polycarbonate copolymer and method of making same

Abstract

The application discloses a high-performance isosorbide-based polycarbonate copolymer and a preparation method thereof, and belongs to the technical field of new materials. The application successfully solves the problems that the biological-based polycarbonate is poor in plasticity and toughness, and the strength, toughness and heat resistance cannot be balanced, and finally successfully prepares the biological-based polycarbonate polymer with high strength, high toughness and high heat resistance through copolymerization of isosorbide, semi-rigid alicyclic glycol and crystallizable oligomer glycol.

Description

Technical Field

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

[0002] Isosorbide-based polycarbonate (IPC) possesses a high glass transition temperature and excellent tensile strength, making it a potential alternative to bisphenol A (BPA) type polycarbonate. However, its rigid isosorbide backbone structure results in poor plasticity and toughness. Therefore, modification to increase the toughness and plasticity of IPC is essential. Modification methods for IPC mainly include physical and chemical modifications. Physical modification primarily involves blending with flexible polycarbonates, but its thermal and optical properties are not stable due to the lack of strong bonding. Chemical modification, by introducing flexible copolymer units into the isosorbide backbone, increases the molecular flexibility of the IPC backbone and is considered the most promising method for improving the plasticity and toughness of IPC.

[0003] However, current chemical modifications of isosorbide-based polycarbonate mostly involve copolymerizing it with flexible glycol monomers to prepare isosorbide-based polycarbonate polymers. While increasing the content of flexible glycols increases plasticity and toughness, it inevitably leads to a significant decrease in strength and glass transition temperature, greatly limiting its application in engineering plastics. A paper (Journal of Applied Polymer Science, 2024, 141:e55605.) prepared isosorbide-based polycarbonate copolymers by copolymerizing isosorbide with ethoxylated isosorbide oligomers. The incorporation of flexible comonomers improved the ductility and processability of isosorbide-based polycarbonate, increasing the elongation at break from 20% to 43%, while decreasing the tensile strength from 89 MPa to 73 MPa. However, the glass transition temperature decreased from 150℃ to 102℃. The paper (Reactive and Functional Polymers, 2020, 155:104689) prepared isosorbide-based polycarbonate copolymers with low-molecular-weight polyethylene glycol via melt transesterification, successfully increasing the flexibility of isosorbide-based polycarbonate with an elongation at break of 176%. However, its glass transition temperature decreased to 105℃, limiting its use in engineering plastics. Therefore, the preparation of high-strength, high-toughness, and high-heat-resistant isosorbide-based polyester-polycarbonate through reasonable control of monomer structure and content still needs to be studied and overcome.

[0004] 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 description of the molecular weight of polyester glycol has an excessively wide range. A more precise range of polyester glycol molecular weights can yield polycarbonate copolymers with better performance, resulting in a better balance between the copolymer's plasticity, toughness, strength, and glass transition temperature. Summary of the Invention

[0005] Technical issues

[0006] Currently, there is still room for improvement in existing technologies related to copolymerized carbonates. A method is needed to enable the copolymer to achieve an excellent level of plasticity, toughness, strength, and glass transition temperature.

[0007] Technical content

[0008] 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 an isosorbide-based polycarbonate copolymer by copolymerizing isosorbide with an alicyclic 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.

[0009] The first objective of this invention is to provide a method for preparing a high-performance isosorbide-based polycarbonate copolymer, the method comprising the following steps:

[0010] (1) Under a protective atmosphere, isosorbide, crystallizable oligomeric diol, alicyclic diol and carbonate diester are heated and melted, and then a catalyst is added to carry out the reaction;

[0011] (2) Under low vacuum conditions, the temperature is raised to 200-280℃ and the reaction time is maintained for 0.2h-5h to obtain high-performance isosorbide-based polyester-polycarbonate copolymer.

[0012] Furthermore, the protective gas in step (1) includes nitrogen and / or an inert gas.

[0013] Furthermore, the crystallizable oligomeric diol in step (1) is polycaprolactone diol.

[0014] Furthermore, the molecular weight of the crystallizable polycaprolactone diol in step (1) is 500 to 800.

[0015] Furthermore, in step (1), the alicyclic diol is selected from at least one of 1,4-cyclohexanediethanol and tricyclodecanediethanol.

[0016] Furthermore, in step (1), the carbonate diester is selected from one of diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and dibutyl carbonate.

[0017] Furthermore, the molar ratio of isosorbide to crystallizable oligomeric diol is 1:0.03 to 0.1.

[0018] Furthermore, the molar ratio of isosorbide to alicyclic diol is 1:0.03 to 0.2.

[0019] Furthermore, the molar ratio of isosorbide to diester is 1:1 to 10.

[0020] Preferably, the molar ratio of isosorbide to diester is 1:1 to 5.

[0021] Specifically, the molar ratio of isosorbide to diester is 1:1 to 2.

[0022] Furthermore, the heating and melting temperature in step (1) is 90–150°C.

[0023] Furthermore, the catalyst mentioned in step (1) is at least one of a metal catalyst, a basic catalyst, and an ionic liquid catalyst.

[0024] Furthermore, the metal catalyst is one of sodium tert-butoxide, lithium acetylacetonate, and potassium carbonate.

[0025] Furthermore, the alkaline catalyst is one of 1,5,7-triazabicyclo[4.4.0]decen-5-ene (TBD) and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0026] Furthermore, the ionic liquid catalyst is one of 1-ethyl-3-methylimidazolium lactate and 1-butyl-3-methylimidazolium lactate.

[0027] Furthermore, the molar amount of catalyst added in step (1) is 0.005-0.01% of the molar amount of diester.

[0028] Furthermore, the reaction time in step (1) is 1 to 5 hours.

[0029] Furthermore, the low vacuum condition mentioned in step (2) refers to a vacuum degree of less than 100 Pa.

[0030] Furthermore, the low vacuum condition mentioned in step (2) refers to a vacuum degree of 10 to 100 Pa.

[0031] A second object of the present invention is to provide an isosorbide-based polycarbonate copolymer prepared according to the above method.

[0032] Furthermore, the isosorbide-based polycarbonate copolymer has a tensile strength of not less than 70 MPa, an elongation at break of not less than 60%, 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 not less than 7 × 10⁻⁶. 4 Da.

[0033] Furthermore, the isosorbide-based polycarbonate copolymer has a tensile strength of 70-85 MPa, an elongation of 60-100%, a glass transition temperature of 130-136 °C, and a pencil hardness of 2H-3H.

[0034] A third objective of this invention is the application of the provided isosorbide-based polycarbonate copolymer in the fields of electronics, food packaging, building materials, containers, transportation vehicles, engineering plastics, or medical devices.

[0035] The beneficial effects of this invention are as follows:

[0036] 1. Compared to existing technologies, this invention uses crystallizable oligomeric diols (molecular weight 500-800). These oligomeric diols have more polar ester groups than smaller molecule diols and can form microcrystals in the polymer. Therefore, introducing crystallizable oligomeric diols into the isosorbide-based polycarbonate backbone imparts higher tensile strength and glass transition temperature to the backbone compared to smaller molecule diols. Furthermore, the longer alkane segments in the crystallizable oligomeric diols effectively increase the elongation at break and toughness of the bio-based polycarbonate copolymer. However, excessively high molecular weight oligomeric diols significantly reduce the strength and heat resistance of the resulting polymer. Therefore, oligomeric diols with a molecular weight of 500-800 achieve the best technical results.

[0037] 2. Compared with the prior art, the present invention found that when the molecular weight of crystallizable oligomeric diol is ≥500, the addition of alicyclic diol can have a synergistic effect on increasing the elongation at break of the copolymer, thereby increasing the elongation at break to more than 70% while basically maintaining other excellent properties.

[0038] 3. The high-performance bio-based polycarbonate copolymer in this invention has better properties, with a tensile strength of 70-85 MPa, an elongation of 60-100%, and a glass transition temperature of 130-136℃. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the appendix and examples. 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%, polycaprolactone diol (PCL diol) has a purity greater than 99%, 1,4-cyclohexanediethanol has a purity of 98%, tricyclodecanediethanol (≥90%), sodium tert-butoxide, lithium acetylacetonate, potassium carbonate, 1,5,7-triazabicyclo[4.4.0]decen-5-ene (TBD), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1-ethyl-3-methylimidazolium lactate, and 1-butyl-3-methylimidazolium lactate all have a purity of 99%.

[0040] Testing process

[0041] 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 1260GPC at 1 mL / min. N,N-dimethylformamide was used as the mobile phase, and polystyrene was used as the standard.

[0042] 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 dual-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.

[0043] 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 -20 °C to 200 °C at a rate of 10 °C / min. The inflection point was taken as the glass transition temperature.

[0044] Transmittance: Tested using Shimadzu UV-3600plus from 400-800nm, with a sample thickness of 0.2mm. Transmittance data was taken from 550nm.

[0045] Pencil hardness: Tested using a Shanghai Pushen BY pencil hardness tester according to national standard GB / T 6739-2006.

[0046] Example 1

[0047] 10.86 g isosorbide, 17.31 g diphenyl carbonate, 1.7 g PCL glycol (Mn = 530) and 0.576 g 1,4-cyclohexanediethanol 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.

[0048] The mechanical and thermal properties of the copolymer are shown in Table 1.

[0049] Example 2

[0050] Similar to Example 1, 1-butyl-3-methylimidazolium lactate was replaced with an equimolar amount of sodium tert-butoxide, while other conditions remained unchanged, to obtain a copolymer with a yield of 91% and a weight-average molecular weight of 91,400.

[0051] Example 3

[0052] 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 93% and a weight-average molecular weight of 96,800.

[0053] Example 4

[0054] Similar to Example 1, 1-butyl-3-methylimidazolium lactate was replaced with an equimolar amount of potassium carbonate, while other conditions remained unchanged, to obtain a copolymer with a yield of 87% and a weight-average molecular weight of 86,900.

[0055] Example 5

[0056] 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 89% and a weight-average molecular weight of 85,300.

[0057] Example 6

[0058] Same as in Example 1, but 1-butyl-3-methylimidazolium lactate was replaced with an equimolar amount of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and other conditions remained unchanged, to obtain a copolymer with a yield of 86% and a weight-average molecular weight of 78,700.

[0059] Example 7

[0060] 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 96% and a weight-average molecular weight of 108,900.

[0061] Example 8

[0062] 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 110,700.

[0063] Example 9

[0064] Same as in Example 1, but with the raw materials replaced by 10.30g isosorbide, 17.31g diphenyl carbonate, 1.7g PCL diol (Mn=530) and 1.152g 1,4-cyclohexanediethanol, and other conditions unchanged, the yield was 98% and the weight average molecular weight of the product was 115,500.

[0065] Example 10

[0066] Same as in Example 1, but with the raw materials replaced by 10.86g isosorbide, 17.31g diphenyl carbonate, 1.7g PCL glycol (Mn=530) and 0.872g tricyclodecanediol, and other conditions unchanged, a copolymer was obtained with a yield of 98% and a weight-average molecular weight of 113200.

[0067] Example 11

[0068] Same as in Example 1, but with the raw materials replaced by 10.30g isosorbide, 17.31g diphenyl carbonate, 1.7g PCL glycol (Mn=530) and 1.745g tricyclodecanediol, and other conditions unchanged, a copolymer was obtained with a yield of 94% and a weight-average molecular weight of 96,500.

[0069] Comparative Example 1

[0070] 10.86 g isosorbide, 17.31 g diphenyl carbonate, 1.28 g PCL glycol (Mn = 400) and 0.576 g 1,4-cyclohexanediethanol were added to a three-necked flask and melted at 135 °C under a nitrogen atmosphere. Then, 1 mg 1-butyl-3-methylimidazolium lactate was added and the mixture was 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 increased 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 103,900.

[0071] Comparative Example 2

[0072] Similar to Comparative Example 1, the raw materials were replaced with 10.86 g isosorbide, 17.31 g diphenyl carbonate, 2.68 g PCL glycol (Mn = 830), and 0.576 g 1,4-cyclohexanediethanol, with other conditions remaining unchanged, to obtain a copolymer with a yield of 96% and a weight-average molecular weight of 118,200.

[0073] Comparative Example 3

[0074] Similar to Comparative Example 1, the raw materials were replaced with 10.86 g isosorbide, 17.31 g diphenyl carbonate, 3.2 g PCL glycol (Mn = 1000) and 0.576 g 1,4-cyclohexanediethanol, with other conditions remaining unchanged, to obtain a copolymer with a yield of 95% and a weight-average molecular weight of 119,700.

[0075] Comparative Example 4

[0076] Same as Example 1, except that the use of 1,4-cyclohexanediethanol was omitted, and other conditions remained unchanged, to obtain a copolymer with a yield of 96% and a weight-average molecular weight of 113,900.

[0077] Comparative Example 5

[0078] Same as Example 1, except that the use of PCL diol (Mn = 530) was omitted, and other conditions remained unchanged, to obtain a copolymer with a yield of 97% and a weight-average molecular weight of 111,600.

[0079] Table 1. Performance Comparison of Examples and Comparative Examples

[0080] Example 1 81±5 76±5 136 91.0 3H Example 2 76±4 70±4 134 90.4 3H Example 3 77±3 72±3 134 90.6 3H Example 4 75±3 65±5 133 90.4 3H Example 5 74±4 64±5 133 90.5 2H Example 6 70±4 63±3 135 90.4 2H Example 7 77±5 70±4 136 90.9 3H Example 8 77±4 73±5 136 90.5 3H Example 9 74±4 85±8 130 90.1 2H Example 10 80±3 72±5 134 90.2 3H Example 11 73±3 100±6 130 88.2 2H Comparative Example 1 80±5 30±5 138 90.4 3H Comparative Example 2 68±3 110±10 123 90.5 H Comparative Example 3 62±3 150±15 112 90.4 2B Comparative Example 4 75±5 30±4 142 90.5 2H Comparative Example 5 80±5 20±3 147 91.2 4H

[0081] Based on the data in Table 1, it can be seen that the copolymers obtained in Examples 1-11 have better plasticity, toughness, strength, and glass transition temperature coordination than the copolymers obtained in Comparative Examples 1-3. In contrast, the comparative examples either had poor elongation at break (Comparative Examples 1, 4-5), low hardness (Comparative Examples 2, 3), or low glass transition temperature (Comparative Examples 2, 3), and none of them could produce a polycarbonate copolymer with balanced and excellent performance. This indicates that there is a more favorable selection of the molecular weight of PCL glycol, which can achieve better performance coordination of isosorbide-based polycarbonate copolymers.

[0082] Furthermore, data from Examples 1 and Comparative Examples 1-5 show that polycaprolactone diol (Mn≥500) and semi-rigid 1,4-cyclohexanediethanol have a synergistic effect on the elongation at break of isosorbide-based polycarbonate copolymers. The resulting copolymer has a significantly higher elongation at break than the sum of the elongation at break of polycaprolactone diol alone and the elongation at break of 1,4-cyclohexanediethanol alone. However, when the molecular weight of polycaprolactone diol is too low (Mn≤400), the elongation at break of the copolymer does not increase significantly when polycaprolactone diol and 1,4-cyclohexanediethanol are used together.

[0083] 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. An isosorbide-based polycarbonate copolymer with high strength, high toughness, and high heat resistance, characterized in that, The isosorbide-based polycarbonate copolymer has a tensile strength of 70-85 MPa, an elongation of 60-100%, a glass transition temperature of 130-136°C, and a pencil hardness of 2H-3H. The isosorbide-based polycarbonate copolymer was prepared according to the following method: (1) Under a protective atmosphere, isosorbide, crystallizable oligomeric diol, alicyclic diol and carbonate diester are heated and melted, and then a catalyst is added to carry out the reaction; The crystallizable oligomeric diol is polycaprolactone diol with a molecular weight of 500-530; the molar ratio of isosorbide to crystallizable oligomeric diol is 1:0.03-0.1; the molar ratio of isosorbide to alicyclic diol is 1:0.03-0.2; and the molar ratio of isosorbide to diester is 1:1-10. The catalyst is one of sodium tert-butoxide, lithium acetylacetonate, potassium carbonate, 1,5,7-triazabicyclo[4.4.0]decen-5-ene (TBD), 1,8-diazabicyclo[5.4.0]undec-7-ene, 1-ethyl-3-methylimidazolium lactate, and 1-butyl-3-methylimidazolium lactate; the molar amount of the catalyst added is 0.005-0.01% of the molar amount of the diester. The alicyclic diol is selected from at least one of 1,4-cyclohexanediethanol and tricyclodecanediethanol; Dicarbonate is selected from one of diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and dibutyl carbonate; (2) Under low vacuum conditions, the temperature is raised to 200-280°C and the reaction time is maintained for 0.2h-5h to obtain high-performance isosorbide-based polycarbonate copolymer.

2. The isosorbide-based polycarbonate copolymer according to claim 1, characterized in that, The protective gas in step (1) includes nitrogen and / or an inert gas.

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

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

5. The isosorbide-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 isosorbide-based polycarbonate copolymer according to claim 1, characterized in that, The relative weight-average molecular weight of isosorbide-based polycarbonate copolymers is not less than 7 × 10⁻⁶. 4 Da.

7. The application of the isosorbide-based polycarbonate copolymer of claim 1 in the fields of electronics, food packaging, building materials, containers, vehicles, engineering plastics or medical devices.