High-performance isosorbide-based polycarbonate copolymer and preparation method thereof

Abstract

The invention discloses a high-performance isosorbide-based polycarbonate copolymer and a preparation method thereof, and belongs to the technical field of new materials. The problems that the plasticity and toughness of bio-based polycarbonate are poor, and the strength, toughness and heat resistance cannot be balanced are successfully solved, and finally, the high-strength, high-toughness and high-heat-resistance bio-based polycarbonate polymer is successfully prepared through copolymerization of isosorbide, semi-rigid alicyclic diol and crystallizable oligomer diol.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and in particular relates to a high-performance isosorbide-based polycarbonate copolymer and a preparation method thereof. Background Art

[0002] Isosorbide-based polycarbonate (IPC) has a high glass transition temperature and excellent tensile strength, making it a potential alternative to bisphenol A-based polycarbonate. However, due to its rigid isosorbide backbone structure, its plasticity and toughness are poor, making it necessary to increase the toughness and plasticity of IPC through modification. There are two main methods for modifying IPC: physical modification and chemical modification. 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 involves introducing flexible copolymer units into the isosorbide backbone to increase the molecular flexibility of the IPC backbone. This is considered the most promising method for increasing the plasticity and toughness of IPC.

[0003] However, current chemical modifications of isosorbide-based polycarbonates mostly involve copolymerization with flexible diol monomers to prepare isosorbide-based polycarbonate polymers. As the flexible diol content increases, plasticity and toughness increase, but strength and glass transition temperature decrease significantly, significantly limiting its application in engineering plastics. A paper (Journal of Applied Polymer Science, 2024, 141: e55605.) copolymerizes isosorbide with ethoxylated isosorbide oligomers to prepare isosorbide-based polycarbonate copolymers. The incorporation of the flexible comonomer improves the ductility and processability of isosorbide-based polycarbonate, increasing its elongation at break from 20% to 43% and reducing its tensile strength from 89 MPa to 73 MPa. However, the glass transition temperature decreases from 150°C to 102°C. The paper (Reactive and Functional Polymers, 2020, 155:104689) prepared isosorbide-based polycarbonate copolymers by melt transesterification of isosorbide and low-molecular-weight polyethylene glycol, successfully increasing the flexibility of isosorbide-based polycarbonate, with an elongation at break of 176%. However, its glass transition temperature dropped to 105°C, limiting its use in engineering plastics. Therefore, the preparation of high-strength, high-toughness, and high-heat-resistant isosorbide-based polyester-polycarbonate by reasonable monomer structure and content regulation still needs to be studied and overcome.

[0004] A copolymer carbonate disclosed in patent CN 105237755 A has low water absorption, excellent heat resistance, low temperature characteristics and surface hardness. However, the present application finds that the molecular weight range of the polyester diol is too wide, and a more accurate polyester diol molecular weight range can obtain a better copolymer carbonate, so that the plasticity, toughness, strength and glass transition temperature of the copolymer are more excellent. SUMMARY

[0005] TECHNICAL PROBLEM

[0006] At present, there is still optimization space for the copolymer carbonate technology in the prior art, and a method is needed to make the plasticity, toughness, strength and glass transition temperature of the copolymer reach an excellent level.

[0007] TECHNICAL CONTENT

[0008] In view of the above problems existing in the prior art, the present application provides a high-performance bio-based polycarbonate copolymer and a preparation method thereof. The present application prepares an isosorbide-based polycarbonate copolymer by copolymerizing isosorbide, alicyclic diol and crystallizable oligomer diol. The copolymer not only has high strength, high toughness and high transparency, but also has high heat resistance. It is a very potential bio-based engineering plastic.

[0009] The first object of the present application is to provide a preparation method of a high-performance isosorbide-based polycarbonate copolymer, which comprises the following steps:

[0010] (1) heating and melting isosorbide, crystallizable oligomer diol, alicyclic diol and carbonic diester under a protective atmosphere, and then adding a catalyst for reaction;

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

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

[0013] Further, the crystallizable oligomer diol in step (1) is polycaprolactone diol.

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

[0015] Further, the alicyclic diol in step (1) is at least one selected from 1,4-cyclohexane dimethanol and tricyclodecane dimethylol.

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

[0017] Further, the molar ratio of isosorbide to the crystallizable oligomer diol is 1:0.03-0.1.

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

[0019] Further, the molar ratio of isosorbide to the carbonic acid diester is 1:1-10.

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

[0021] More preferably, the molar ratio of isosorbide to the carbonic acid diester is 1:1-2.

[0022] Further, the temperature for heating and melting in step (1) is 90-150℃.

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

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

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

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

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

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

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

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

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

[0032] Further, 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 x 10 4 Da.

[0033] Further, 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 object of the present application is the use of the isosorbide-based polycarbonate copolymer in the fields of electronic appliances, food packaging, building materials, containers, vehicles, engineering plastics, or medical devices.

[0035] The present application has the following advantages:

[0036] 1. Compared with the prior art, the present application uses crystallizable oligomer diols (molecular weight 500-800), which have larger polar ester groups than small molecule diols and can form microcrystals in the polymer, so that the introduction of crystallizable oligomer diols into the isosorbide-based polycarbonate backbone can impart higher tensile strength and glass transition temperature to the backbone than small molecule diols, and the longer alkane chain segments in the crystallizable oligomer diols can effectively increase the elongation at break and toughness of the bio-based polycarbonate copolymer. However, if the molecular weight of the oligomer diol is too high, the strength and heat resistance of the resulting polymer will be significantly reduced, so the oligomer diol with a molecular weight of 500-800 can achieve the best technical effect.

[0037] 2. Compared with the prior art, the present application finds that the addition of alicyclic diols can have a synergistic effect on the increase of the elongation at break of the copolymer when the molecular weight of the crystallizable oligomer diol is ≥500, while maintaining other excellent properties, the elongation at break is increased to more than 70%.

[0038] 3. The high-performance bio-based polycarbonate copolymer of the present application has better performance, with a tensile strength of 70-85 MPa, an elongation of 60-100%, and a glass transition temperature of 130-136°C. DETAILED DESCRIPTION

[0039] The present application is specifically described below in combination with the appended tables and examples. The raw materials used in the examples of the present application are commercially available, unless otherwise specified; among them, the purity of isosorbide is greater than 98%, the purity of diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate and dibutyl carbonate is 99%, the purity of polycaprolactone diol (PCL diol) is greater than 99%, the purity of 1,4-cyclohexane dimethanol is 98%, the purity of tricyclodecane dimethanol (≥90%), the purity of sodium tert-butoxide, lithium acetylacetonate, potassium carbonate, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1-ethyl-3-methylimidazolium lactate and 1-butyl-3-methylimidazolium lactate is all 99%.

[0040] Detection process

[0041] Gel permeation chromatography: 5 mg of sample was dissolved in 2 mL of spectroscopic grade N,N-dimethylformamide, filtered using a 0.22 μm organic filter membrane, and then tested using an Agilent 1260 GPC at a flow rate of 1 mL / min, with N,N-dimethylformamide as the mobile phase and polystyrene as the standard.

[0042] Mechanical properties: The sample was cut into dumbbell-shaped samples with a width of 4 mm, a thickness of 0.5 mm and a length of 18 mm, and tested using an Instron 5967X dual-column benchtop testing system at a room temperature and a tensile rate of 10 mm / min. Five samples were taken for each sample, and the average value was calculated with an error.

[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, it was heated from 30°C to 200°C at a rate of 30°C / min, held for 1 min, then cooled from 200°C to -20°C at a rate of 30°C / min, held for 1 min, and finally heated 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: The transmittance was tested using a Shimadzu UV-3600plus from 400-800 nm, with a sample thickness of 0.2 mm, and the transmittance was taken from the data at 550 nm.

[0045] Pencil hardness: The pencil hardness was tested using a Shanghai Posh BY pencil hardness tester according to the national standard GBT 6739-2006.

[0046] Example 1

[0047] Into a three-necked flask, 10.86 g of isosorbide, 17.31 g of diphenyl carbonate, 1.7 g of PCL diol (Mn = 530) and 0.576 g of 1,4-cyclohexanedimethanol were added, heated at 135 °C under N2 atmosphere, after the raw materials were melted, 1 mg of 1-butyl-3-methylimidazolium lactate was added, and the ester exchange process was carried out by mechanical stirring for 4 h; then the nitrogen was turned off and the vacuum degree was adjusted to 80 Pa, and then the temperature was continuously raised to 250 °C to carry out the polycondensation process, and the reaction was stopped after 0.5 h to obtain the copolymer, with a yield of 98% and a weight average molecular weight of the product of 112500.

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

[0049] Example 2

[0050] The same as Example 1, 1-butyl-3-methylimidazolium lactate was replaced by an equal molar amount of sodium tert-butoxide, and other conditions were unchanged, to obtain the copolymer, with a yield of 91% and a weight average molecular weight of the product of 91400.

[0051] Example 3

[0052] The same as Example 1, 1-butyl-3-methylimidazolium lactate was replaced by an equal molar amount of lithium acetylacetonate, and other conditions were unchanged, to obtain the copolymer, with a yield of 93% and a weight average molecular weight of the product of 96800.

[0053] Example 4

[0054] The same as Example 1, 1-butyl-3-methylimidazolium lactate was replaced by an equal molar amount of potassium carbonate, and other conditions were unchanged, to obtain the copolymer, with a yield of 87% and a weight average molecular weight of the product of 86900.

[0055] Example 5

[0056] The same as Example 1, 1-butyl-3-methylimidazolium lactate was replaced by an equal molar amount of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and other conditions were unchanged, to obtain the copolymer, with a yield of 89% and a weight average molecular weight of the product of 85300.

[0057] Example 6

[0058] The same as Example 1, 1-butyl-3-methylimidazolium lactate was replaced by an equal molar amount of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and other conditions were unchanged, to obtain the copolymer, with a yield of 86% and a weight average molecular weight of the product of 78700.

[0059] Example 7

[0060] The same as Example 1, 1-butyl-3-methylimidazolium lactate was replaced by equimolar amount of 1-ethyl-3-methylimidazolium lactate, and other conditions were unchanged, to obtain the copolymer with a yield of 96% and a weight average molecular weight of the product of 108900.

[0061] Example 8

[0062] The same as Example 1, the temperature in the polycondensation process was adjusted to 240°C, and other conditions were unchanged, to obtain the copolymer with a yield of 96% and a weight average molecular weight of the product of 110700.

[0063] Example 9

[0064] The same as Example 1, the raw materials were replaced by 10.30 g of isosorbide, 17.31 g of diphenyl carbonate, 1.7 g of PCL diol (Mn = 530) and 1.152 g of 1,4-cyclohexane dimethanol, and other conditions were unchanged, to obtain the copolymer with a yield of 98% and a weight average molecular weight of the product of 115500.

[0065] Example 10

[0066] The same as Example 1, the raw materials were replaced by 10.86 g of isosorbide, 17.31 g of diphenyl carbonate, 1.7 g of PCL diol (Mn = 530) and 0.872 g of tricyclodecane dimethanol, and other conditions were unchanged, to obtain the copolymer with a yield of 98% and a weight average molecular weight of the product of 113200.

[0067] Example 11

[0068] The same as Example 1, the raw materials were replaced by 10.30 g of isosorbide, 17.31 g of diphenyl carbonate, 1.7 g of PCL diol (Mn = 530) and 1.745 g of tricyclodecane dimethanol, and other conditions were unchanged, to obtain the copolymer with a yield of 94% and a weight average molecular weight of the product of 96500.

[0069] Comparative Example 1

[0070] 10.86 g of isosorbide, 17.31 g of diphenyl carbonate, 1.28 g of PCL diol (Mn = 400) and 0.576 g of 1,4-cyclohexane dimethanol were added to a three-necked flask, 1 mg of 1-butyl-3-methylimidazolium lactate was added after melting at 135°C under N2 atmosphere, mechanical stirring was carried out for 4 h, then the nitrogen was turned off and the vacuum degree was adjusted to 80 Pa, and then the temperature was continuously increased to 250°C, the reaction was carried out for 0.5 h, and then the copolymer was obtained with a yield of 97% and a weight average molecular weight of the product of 103900.

[0071] Comparative Example 2

[0072] The same as Comparative Example 1, the raw materials were replaced with 10.86g isosorbide, 17.31g diphenyl carbonate, 2.68g PCL diol (Mn=830) and 0.576g 1,4-cyclohexanedimethanol, and other conditions remained unchanged to obtain a copolymer with a yield of 96% and a weight-average molecular weight of 118200.

[0073] Comparative Example 3

[0074] The same as Comparative Example 1, the raw materials were replaced with 10.86g isosorbide, 17.31g diphenyl carbonate, 3.2g PCL diol (Mn=1000) and 0.576g 1,4-cyclohexanedimethanol, and other conditions remained unchanged to obtain a copolymer with a yield of 95% and a weight-average molecular weight of 119700.

[0075] Comparative Example 4

[0076] The same method as Example 1 was used, except that 1,4-cyclohexanedimethanol was omitted and other conditions remained unchanged. A copolymer was obtained with a yield of 96% and a weight-average molecular weight of 113,900.

[0077] Comparative Example 5

[0078] The same method as Example 1 was used, except that PCL diol (Mn=530) was omitted and other conditions remained unchanged. A copolymer was obtained with a yield of 97% and a weight-average molecular weight of 111,600.

[0079] Table 1 Performance comparison between examples and comparative examples

[0080] Example Tensile strength / MPa Elongation at break / % Glass transition temperature / °C Transmittance / % Pencil hardness 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] According to the data in Table 1, it can be seen that the copolymers obtained in Examples 1 to 11 have better coordination of plasticity, toughness, strength, and glass transition temperature than the copolymers obtained in Comparative Examples 1 to 3. In contrast, the comparative examples either have poor elongation at break (Comparative Examples 1, 4 to 5), low hardness (Comparative Examples 2 and 3), or too low glass transition temperature (Comparative Examples 2 and 3), and none of them can produce a polycarbonate copolymer with excellent balanced performance. This indicates that there are more excellent choices for the molecular weight of PCL diol, which can achieve better performance coordination of isosorbide-based polycarbonate copolymers.

[0082] Furthermore, from the data of Example 1 and Comparative Examples 1 to 5, it is known that polycaprolactone diol (Mn≥500) and semi-rigid 1,4-cyclohexane dimethanol have a synergistic effect on the elongation at break of the isosorbide-based polycarbonate copolymer, and the elongation at break of the obtained copolymer is significantly greater than the sum of the elongation at break of the polycaprolactone diol alone and the elongation at break of the 1,4-cyclohexane dimethanol alone, and when the molecular weight of the polycaprolactone diol is too low (Mn≤400), the elongation at break of the copolymer does not significantly increase when the polycaprolactone diol and the 1,4-cyclohexane dimethanol are used together.

[0083] The above provided examples are not intended to limit the scope encompassed by the present application, and the described steps are not intended to limit the order of execution. Those skilled in the art make obvious improvements to the present application in combination with the existing common knowledge, which also falls within the protection scope defined by the claims of the present application.

Claims

1. A method for preparing a high-performance isosorbide-based polycarbonate copolymer, characterized in that: The preparation method comprises the following steps: (1) Under a protective gas atmosphere, isosorbide, a crystallizable oligomer diol, an alicyclic diol, and a carbonate diester are heated and melted, and then a catalyst is added to react; The crystallizable oligomer diol is polycaprolactone diol with a molecular weight of 500 to 800; the molar ratio of isosorbide to the crystallizable oligomer diol is 1:0.03 to 0.1; the molar ratio of isosorbide to the alicyclic diol is 1:0.03 to 0.2; and the molar ratio of isosorbide to the carbonic acid diester is 1:1 to 10; The catalyst is one of sodium tert-butoxide, lithium acetylacetonate, potassium carbonate, 1,5,7-triazabicyclo[4.4.0]decene-5-ene (TBD), 1,8-diazabicyclo[5.4.0]undec-7-ene, 1-ethyl-3-methylimidazole lactate, and 1-butyl-3-methylimidazole lactate; the molar amount of the catalyst added is 0.005-0.01% of the molar amount of the carbonate diester; (2) Under low vacuum conditions, the temperature is raised to 200-280° C., and the reaction time is continued for 0.2 h to 5 h to obtain a high-performance isosorbide-based polyester-polycarbonate copolymer.

2. The preparation method according to claim 1, characterized in that In step (1), the protective gas includes nitrogen and / or an inert gas.

3. The preparation method according to claim 1, characterized in that In step (1), the alicyclic diol is selected from at least one of 1,4-cyclohexanedimethanol and tricyclodecane dimethanol.

4. The preparation method according to claim 1, wherein In step (1), the carbonic acid diester is selected from one of diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate and dibutyl carbonate.

5. The preparation method according to claim 1, wherein The heating and melting temperature in step (1) is 90 to 150°C.

6. The preparation method according to claim 1, wherein The reaction time in step (1) is 1 to 5 hours.

7. The preparation method according to claim 1, characterized in that The low vacuum condition in step (2) refers to a condition where the vacuum degree is less than 100 Pa.

8. An isosorbide-based polycarbonate copolymer, characterized in that The isosorbide-based polycarbonate copolymer is prepared according to the preparation method according to any one of claims 1 to 8.

9. The isosorbide-based polycarbonate copolymer according to claim 8, wherein The relative weight average molecular weight of the isosorbide-based polycarbonate copolymer is not less than 7×10 4 Da.

10. Use of the isosorbide-based polycarbonate copolymer according to claim 8 in the fields of electronic appliances, food packaging, building materials, containers, vehicles, engineering plastics or medical devices.