Method for preparing isohexide-based polycarbonate copolymer

Abstract

The present invention relates to a method for preparing an isohexide-based polycarbonate copolymer. The isohexide-based polycarbonate copolymer is obtained by sequentially carrying out a transesterification reaction, a pre-polycondensation reaction, and a final polycondensation reaction on diol and dialkyl carbonate under the action of a catalyst, wherein the diol includes diol A1 and diol A2, or further includes diol A3; the diol A1 is isohexide; the molecular structural formula of the diol A2 contains a cyclic ether structure and two primary hydroxyl groups, and the primary hydroxyl groups are linked to the cyclic ether structure via a methylene group; the diol A3 is a dihydroxy compound; and during the pre-polycondensation reaction, the temperature is first gradually increased to 180-200ºC within 5-15 min, the pressure is gradually reduced to 45-55 kPa within 5 min, and finally, gradient heating and gradient pressure reduction are carried out. The copolymer prepared by the present invention has high molecular weight, high heat resistance, high strength, high toughness, and transparency, and thus has a wide range of applications.

Description

A preparation method of isohexide-based polycarbonate copolymer Technical Field

[0001] The invention belongs to the field of polycarbonate preparation and relates to a method for preparing an isohexitol-based polycarbonate copolymer. Background Art

[0002] Polycarbonate (PC), due to its excellent thermal, mechanical, and optical properties, is widely used in automotive parts, electronics / electrical products, films / sheets, appliances / household goods, and optical media. It has become one of the five fastest-growing engineering plastics, with bisphenol A polycarbonate (BPA-PC) being the most representative. However, bisphenol A (BPA), one of the main raw materials for BPA-PC, is chronically toxic and can disrupt the human endocrine system. Studies have shown that BPA in plastic products can penetrate into food and beverages and enter the human body, posing a health risk to humans, especially infants. Several countries have implemented policies banning the use of BPA in plastic products, such as baby bottles. Furthermore, BPA is derived from non-renewable petroleum-based resources. In response to calls for green chemistry and sustainable development, it is crucial to identify green monomers that can replace BPA and develop safer, greener processes.

[0003] Unlike petroleum-based resources, bio-based resources are derived from renewable, green resources such as sugar, starch, cellulose, and vegetable oils. Replacing traditional petroleum-based resources with bio-based resources can reduce oil consumption and achieve carbon dioxide emissions. In recent years, polymers based on green, renewable bio-based resources have become a research hotspot. Among them, carbohydrates have attracted widespread attention due to their wide availability, low cost, easy availability, and stereochemical diversity. Isohexides (1,4:3,6-dianhydrohexitol) are a class of carbohydrate-derived diols with high rigidity, chirality, hydrophilicity, and low toxicity. They hold great promise for the preparation of novel bio-based, biodegradable polymer materials. Among them, isosorbide (IS) has been industrially produced on a large scale and is considered a highly promising monomer to replace bisphenol A.

[0004] The literature "Macromolecules, 2006, 39(26):9064-70; Journal of Industrial and Engineering Chemistry, 2016, 37, 42-6; Green Chemistry, 2020, 22(8):2488-97." points out that isosorbide-based polycarbonate (PIC) can be successfully prepared by reacting isosorbide with diphosgene / triphosgene or diphenyl carbonate (DPC) / dimethyl carbonate (DMC). Compared with BPA-PC, PIC has higher elastic modulus and tensile strength, and has better transparency and UV resistance. However, the preparation and application of PIC still have the following problems:

[0005] (1) The reactivity of the two secondary hydroxyl groups of isosorbide is low, and the different conformations of the two hydroxyl groups lead to differences in reactivity, making it difficult to prepare high molecular weight polycarbonate;

[0006] (2) Due to its high melt viscosity, PIC is difficult to stir in the later stage of melt polymerization and polycondensation, and small molecules are difficult to remove, so high molecular weight polycarbonate cannot be prepared, and the later processing will be subject to certain restrictions;

[0007] (3) Due to the high rigidity of isosorbide, PIC is brittle, and its toughness and processability are poor, which limits its industrial application. Therefore, in order to obtain high-performance isosorbide-based polycarbonate, the above problems must be solved.

[0008] To solve problem (1), the document "Green Chemistry, 2021, 23, 973." discloses a series of highly active imidazole-based ionic liquid catalysts composed of halogen anions, the weight-average molecular weight of the PIC synthesized by the catalyst can reach 98,700 g / mol. To further solve problems (2) and (3), copolymerization of isosorbide with flexible monomers is an effective solution. Patent CN111138650A discloses a high molecular weight and high flexibility bio-based polycarbonate copolymer and its preparation method. The patent successfully improves the flexibility of PIC by copolymerizing with an aliphatic diol containing an ether bond, and the elongation at break can be as high as 176%. However, the glass transition temperature of the high molecular weight and high flexibility bio-based polycarbonate copolymer finally prepared is only 78-105°C, which does not meet the requirements of high heat-resistant applications, and its mechanical strength is not mentioned. The paper "Polymer, 2019, 179, 121685" prepared a series of high heat-resistant (T g:157.8-173.5℃), high strength (fiber tensile strength 83-185MPa), high molecular weight (weight average molecular weight: 73,000-103,000g / mol) copolycarbonates, but their elongation at break is less than 10%. The paper "Modern Chemical Industry, 2018, 38(08):130-134. " prepared a series of copolycarbonates by copolymerizing IS with linear diols. With the increase of carbon chain length and the decrease of IS content, the elongation at break of the copolycarbonates increased from 7.5% to 575.2%, but its tensile strength decreased from 84.6MPa to 22.2MPa. The paper "Polymer, 2017, 116, 153-159" reported the synthesis of a series of isosorbide-based copolycarbonates with 1,4-cyclohexanedimethanol (CHDM) that exhibit both high strength (68-69 MPa) and moderate toughness (elongation at break of 50%-100%), but with reduced bio-based content. In summary, obtaining isosorbide-based polycarbonates that combine high molecular weight, high heat resistance, high strength, good toughness, and high bio-based content remains challenging.

[0009] Summary of the Invention

[0010] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for preparing an isohexide-based polycarbonate copolymer. The prepared isohexide-based polycarbonate copolymer has high molecular weight, high heat resistance, high strength, high toughness, and high biocontent, and can be used in the form of engineering plastics or films in electronic devices, automotive parts, packaging materials, medical devices and other fields.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A method for preparing an isohexitol-based polycarbonate copolymer comprises subjecting a diol and a carbonic acid diester to an ester exchange reaction, a preliminary polycondensation reaction, and a final polycondensation reaction in sequence under the action of a catalyst to obtain the isohexitol-based polycarbonate copolymer.

[0013] The diol includes diol A1 and diol A2, or further includes diol A3;

[0014] Diol A1 is isohexitol;

[0015] The molecular structure of diol A2 contains a cyclic ether structure and two primary hydroxyl groups, and the primary hydroxyl group and the cyclic ether structure are connected by a methylene group;

[0016] Diol A3 is a dihydroxy compound;

[0017] The molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.6-0.8:0.1-0.4:0-0.2:1-1.1;

[0018] During the pre-polycondensation reaction, the temperature is first gradually increased to 180-200°C within 5-15 minutes, and then the pressure is gradually reduced to 45-55kPa within 5 minutes. Finally, gradient temperature increase and gradient pressure reduction are performed, that is, each temperature increase of 10°C is maintained for 10-20 minutes, and the pressure is reduced by 3-15kPa at the same time. The total time for gradient temperature increase and gradient pressure reduction is 0.5-1h. The termination conditions of gradient temperature increase and gradient pressure reduction are: temperature of 210-230°C and pressure of 15-30kPa.

[0019] The isohexide-based polycarbonate copolymer of the present invention has high molecular weight, high heat resistance, high strength, high toughness, and high biomass content. The specific reasons are as follows:

[0020] The diols include diol A1 and diol A2, or further include diol A3. Diol A1 serves as the main imparter of rigidity, and diol A2 serves as the main imparter of toughness. The diols have a rigid-flexible structure, imparting toughness to the isohexide-based polycarbonate copolymer while maintaining a certain degree of rigidity, thereby avoiding a significant decrease in the glass transition temperature. Diol A3 serves as a further regulator of rigidity and toughness. Both diol A1 and diol A2 are bio-based monomers.

[0021] The present invention controls the molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester to be 0.6-0.8:0.1-0.4:0-0.2:1-1.1, so that the proportion of diol A1 in the diol is 60%-80%, thereby ensuring high heat resistance and high strength of the isohexide-based polycarbonate copolymer. The proportion of diol A2 is 10%-40%, thereby ensuring that the toughness of the isohexide-based polycarbonate copolymer is improved while ensuring that the heat resistance and strength of the isohexide-based polycarbonate copolymer are not significantly reduced. The proportion of diol A3 is 0-20%, thereby further regulating the rigidity and toughness of the isohexide-based polycarbonate copolymer. In addition, the total proportion of diol A1 and diol A2 in the diol is relatively high, thereby ensuring a high biocontent of the isohexide-based polycarbonate copolymer.

[0022] The molecular structure of the diol A2 controlled by the present invention contains a cyclic ether structure, thus having a certain degree of structural rigidity. At the same time, the molecular structure also contains two primary hydroxyl groups, which are connected to the cyclic ether structure through a methylene group, thus having a certain degree of flexibility. Diol A2 is a bio-based diol monomer that is both rigid and flexible, which can effectively improve melt viscosity and enhance processability. The primary hydroxyl group has a higher reactivity than the secondary hydroxyl group, which can compensate for the insufficient reactivity of diol A1 and increase the molecular weight. In addition, the cyclic ether structure may form hydrogen bonds with the hydroxyl groups of diol A1, acting as an autocatalyst during the polymerization process, thereby increasing the molecular weight. Compared with low-molecular-weight isohexitol-based polycarbonate copolymers, the increase in molecular weight also contributes to an increase in strength.

[0023] The temperature and pressure control of the pre-polycondensation reaction are particularly important. When the temperature is too high, side reactions such as yellowing and thermal degradation are prone to occur. When the temperature is too low, the reaction activity is low and the reaction cannot be fully reacted. When the pressure is too high, the byproduct phenol is difficult to remove and the reaction is difficult to proceed in the forward direction. When the pressure is too low, it will cause bumping, and part of the melt will be extracted, resulting in the loss of reactants, hindering the reaction and even causing pipeline blockage. Therefore, the present invention adopts a method of gradient temperature increase and pressure reduction to control the temperature and pressure within a suitable range, effectively removing phenol while avoiding the removal of oligomers, effectively promoting the reaction, and thus obtaining a high molecular weight isohexide-based polycarbonate copolymer.

[0024] As the preferred technical solution:

[0025] The preparation method of the isohexide-based polycarbonate copolymer as described above, wherein the thermal weight loss 5wt% temperature of the isohexide-based polycarbonate copolymer is ≥345°C, the tensile strength is 65-85MPa, the elongation at break is 60%-110%, and T g ≥110℃, number average molecular weight is 3×10 4 -13×10 4 g / mol.

[0026] In the above-mentioned method for preparing an isohexide-based polycarbonate copolymer, the diol A1 is one or more of isosorbide, isomannide and isoidide.

[0027] The preparation method of the isohexide-based polycarbonate copolymer described above, wherein the diol A2 is IIDML (isoidose-2,5-dimethanol, ), IMDML (isomannose-2,5-dimethanol, )、ISDML(isosorbide-2,5-dimethanol, ), tetrahydrofuran dimethanol furandimethanol Galx-OH(2,3:4,5-di-O-Methylene-galactitol, ), Manx-OH(2,3:4,5-di-O-Methylene-D-mannitol, ), BCD(4,4′-Bicyclohexanone Glycerol Diketal, ), CHD(1,4-Cyclohexanedione Glycerol Diketa, ), CaG(Camphor quinone Diketal Glycerol, ) and CM diol(2,4:3,5-di-O-camphor-D-mannitol, )

[0028] In the above-mentioned method for preparing an isohexide-based polycarbonate copolymer, the diol A3 is one or more of CHDM, CBDO, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol.

[0029] In the preparation method of the isohexide-based polycarbonate copolymer described above, the carbonate diester is one or more of diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, dipentyl carbonate and dioctyl carbonate.

[0030] The preparation method of the isohexide-based polycarbonate copolymer as described above, wherein the catalyst is a metal catalyst, preferably an alkali metal catalyst, which has high catalytic activity for the carbonate exchange process and can promote molecular weight growth; the alkali metal catalyst is one or more of an alkali metal acetylacetonate compound, an alkali metal carbonate, an alkali metal hydroxide and an alkali metal chloride; the alkali metal acetylacetonate compound is one or more of lithium acetylacetonate and lanthanum acetylacetonate; the alkali metal carbonate is one or more of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate; the alkali metal hydroxide is one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide; and the alkali metal chloride is one or more of lithium chloride, sodium chloride and potassium chloride; the catalyst selected in the present invention has good catalytic activity for the carbonate exchange process, reduces the yellowing side reaction, and is conducive to further increasing the molecular weight of the isohexide-based polycarbonate copolymer.

[0031] In the preparation method of the isohexide-based polycarbonate copolymer described above, the molar amount of the catalyst is 1×10 of the total molar amount of the diol. -5 -5×10 -4 .

[0032] As described above, in the preparation method of an isohexide-based polycarbonate copolymer, the transesterification reaction is carried out under the protection of nitrogen or inert gas, the temperature of the transesterification reaction is 120-160°C, the pressure is 0.1 MPa, and the time is 1.5-4 hours; the temperature of the final polycondensation reaction is 230-250°C, the pressure is below 150 Pa, and the time is 0.5-2 hours.

[0033] The preparation method of the isohexide-based polycarbonate copolymer described above, the structural formula of the isohexide-based polycarbonate copolymer is as follows:

[0034] In the formula, x, y, and z are the numbers of repeating units in the isohexide-based polycarbonate copolymer, which may be the same or different, and z may be 0. Beneficial effects:

[0035] (1) A method for preparing an isohexide-based polycarbonate copolymer of the present invention, wherein the introduced diol A2 has two primary hydroxyl groups and has higher reactivity than the secondary hydroxyl groups of isohexide in melt polymerization, wherein the ether bonds of some diols A2, such as IIDML, IMDML or ISDML, can form intermolecular hydrogen bonds with the hydroxyl groups of isohexide, thereby activating the secondary hydroxyl groups of isohexide, and a high molecular weight isohexide-based polycarbonate copolymer can be obtained.

[0036] (2) The preparation method of the present invention effectively avoids the yellowing side reaction caused by the high-temperature pre-polycondensation reaction by using mild pre-polycondensation reaction conditions and catalyst screening, and can obtain a copolymer with good color.

[0037] (3) The diol A2 introduced in the present invention is a green bio-based monomer, which maintains a high bio-based content of the copolymer. At the same time, the preparation process is green and environmentally friendly, and the total reaction time does not exceed 6 hours. In addition, the copolymer prepared by the present invention has good transparency, and the transmittance can reach 87%-92%.

[0038] (4) The present invention solves the problems of low molecular weight, high melt viscosity, difficult processing, poor toughness, and inability of PIC copolymers to achieve heat resistance, strength, toughness, and bio-based content by regulating the polymer structure and the polymerization process. The prepared isohexitol-based polycarbonate copolymer has high molecular weight, high heat resistance, high strength, high toughness, and transparency, and can be used in electronic devices, automotive parts, packaging materials, medical equipment, and other fields. DETAILED DESCRIPTION

[0039] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0040] The structural formula of isohexide-based polycarbonate copolymer is as follows:

[0041] In the formula, x, y, and z are the numbers of repeating units in the isohexide-based polycarbonate copolymer, which may be the same or different, and z may be 0.

[0042] The following is the test method of the relevant performance in the embodiment:

[0043] Thermal weight loss 5 wt% temperature: The thermal weight loss 5 wt% temperature was determined using a thermogravimetric analyzer (TGA, manufactured by NETZSCH Instrument Manufacturing Co., Ltd., Germany, model TG 209 F1). 1-5 mg of sample was weighed and placed in a crucible. Under nitrogen protection, the temperature was raised from 30°C to 600°C at a rate of 10°C / min.

[0044] Tensile strength: GB / T1040-2006 standard was used to test the tensile strength of the isohexide-based polycarbonate copolymer prepared in the examples.

[0045] Elongation at break: The elongation at break of the isohexide-based polycarbonate copolymer prepared in the examples was tested using the GB / T1040-2006 standard.

[0046] T g The glass transition temperature (T) was determined using a differential scanning calorimeter (DSC, manufactured by TA Corporation, USA, model Q20). g ; Weigh 5-10 mg of sample and place it in an aluminum crucible. Under nitrogen protection, heat the temperature from 25°C to 260°C at a rate of 10°C / min and keep it warm for 3 minutes; then cool it down to 25°C at a rate of 10°C / min, keep it warm for 3 minutes, and then heat it to 260°C at a rate of 10°C / min.

[0047] Number average molecular weight: Gel permeation chromatography (GPC) was used to measure the number average molecular weight of the isohexide-based polycarbonate copolymers prepared in the examples.

[0048] Example 1

[0049] A method for preparing an isohexide-based polycarbonate copolymer comprises the following steps:

[0050] (1) Preparation of raw materials;

[0051] Diol A1: isosorbide;

[0052] Diol A2: IIDML;

[0053] Diol A3: CHDM;

[0054] Carbonate diester: diphenyl carbonate;

[0055] Catalyst: lithium acetylacetonate;

[0056] (2) preparing isohexide-based polycarbonate copolymers;

[0057] The diols (diol A1, diol A2, diol A3) and carbonic acid diester are subjected to transesterification reaction, preliminary polycondensation reaction, and final polycondensation reaction in sequence under the action of a catalyst to obtain an isohexide-based polycarbonate copolymer; wherein the molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.6:0.3:0.1:1, and the molar amount of the catalyst is 5×10 of the total molar amount of the diols. -4 ;

[0058] The transesterification reaction was carried out under nitrogen or inert gas protection at a temperature of 130°C, a pressure of 0.1 MPa, and a time of 3 h.

[0059] During the pre-polycondensation reaction, the temperature was first gradually increased to 180°C within 10 minutes, and then the pressure was gradually reduced to 45 kPa within 5 minutes. Finally, a gradient temperature increase and a gradient pressure decrease were performed, i.e., the temperature was increased by 10°C for 15 minutes, and the pressure was reduced by 3-8 kPa. The total time for the gradient temperature increase and the gradient pressure decrease was 60 minutes. The termination conditions of the gradient temperature increase and the gradient pressure decrease were: temperature 220°C and pressure 25 kPa.

[0060] The final polycondensation reaction temperature was 240°C, the pressure was 100 Pa, and the time was 50 min.

[0061] The final isohexide-based polycarbonate copolymer had a thermal weight loss temperature of 5 wt% at 353°C, a tensile strength of 85 MPa, an elongation at break of 92%, and a T g The temperature is 119℃ and the number average molecular weight is 13×10 4 g / mol.

[0062] Comparative Example 1

[0063] A method for preparing an isohexide-based polycarbonate copolymer is basically the same as Example 1, except that: during the pre-polycondensation reaction, the temperature is first gradually increased to 180°C within 10 minutes, then the pressure is gradually reduced to 45 kPa within 5 minutes, and finally the temperature is gradually increased to 220°C within 60 minutes, while the pressure is gradually reduced to 25 kPa.

[0064] The final isohexide-based polycarbonate copolymer had a thermal weight loss of 5 wt% at 345°C, a tensile strength of 78 MPa, an elongation at break of 87%, and a T g The temperature is 117℃ and the number average molecular weight is 2.8×10 4 g / mol.

[0065] By comparing Example 10 with Comparative Example 1, it can be seen that since gradient heating and gradient pressure reduction are not used in the pre-condensation reaction in Comparative Example 1, the molecular weight will decrease. This is because the temperature is raised too quickly and the pressure is too low, which will make the reaction insufficient, and the oligomers may be extracted, which may cause boiling and hinder the growth of molecular weight.

[0066] Example 2

[0067] A method for preparing an isohexide-based polycarbonate copolymer is basically the same as that in Example 1, except that the diol A2 prepared in step (1) is IMDML.

[0068] The thermal weight loss temperature of the isohexide-based polycarbonate copolymer finally obtained was 350°C, the tensile strength was 78 MPa, the elongation at break was 89%, and the T g The temperature is 115℃ and the number average molecular weight is 7×10 4 g / mol.

[0069] Example 3

[0070] A method for preparing an isohexide-based polycarbonate copolymer is basically the same as that in Example 1, except that the diol A2 prepared in step (1) is ISDML.

[0071] The final isohexide-based polycarbonate copolymer had a thermal weight loss temperature of 5 wt% of 348 ° C, a tensile strength of 82 MPa, an elongation at break of 90%, and a T g The temperature is 116℃ and the number average molecular weight is 9×10 4 g / mol.

[0072] Example 4

[0073] A method for preparing an isohexide-based polycarbonate copolymer comprises the following steps:

[0074] (1) Preparation of raw materials;

[0075] Diol A1: isomannide;

[0076] Diol A2: tetrahydrofuran dimethanol;

[0077] Diol A3: 1,3-propylene glycol;

[0078] Carbonate diester: dipropyl carbonate;

[0079] Catalyst: lithium carbonate;

[0080] (2) preparing isohexide-based polycarbonate copolymers;

[0081] The diols (diol A1, diol A2, diol A3) and carbonic acid diester are subjected to transesterification reaction, preliminary polycondensation reaction, and final polycondensation reaction in sequence under the action of a catalyst to obtain an isohexide-based polycarbonate copolymer; wherein the molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.7:0.2:0.1:1.1, and the molar amount of the catalyst is 4×10 of the total molar amount of the diols. -4 ;

[0082] The transesterification reaction is carried out under nitrogen or inert gas protection at a temperature of 140°C, a pressure of 0.1 MPa, and a time of 2.5 h.

[0083] During the pre-polycondensation reaction, the temperature was first gradually increased to 190°C within 10 minutes, and then the pressure was gradually reduced to 50 kPa within 5 minutes. Finally, a gradient temperature increase and gradient pressure reduction were performed, i.e., the temperature was maintained for 15 minutes each time the temperature was increased by 10°C, while the pressure was reduced by 5-10 kPa. The total time for the gradient temperature increase and gradient pressure reduction was 45 minutes. The termination conditions of the gradient temperature increase and gradient pressure reduction were: temperature 220°C and pressure 25 kPa;

[0084] The temperature of the final polycondensation reaction was 235°C, the pressure was 150 Pa, and the time was 80 min.

[0085] The final isohexide-based polycarbonate copolymer had a thermal weight loss temperature of 5 wt% of 348 ° C, a tensile strength of 68 MPa, an elongation at break of 85%, and a T g The temperature is 112℃ and the number average molecular weight is 6×10 4 g / mol.

[0086] Example 5

[0087] A method for preparing an isohexide-based polycarbonate copolymer is basically the same as that in Example 4, except that the diol A2 prepared in step (1) is furan dimethanol.

[0088] The thermal weight loss temperature of the isohexide-based polycarbonate copolymer finally obtained was 350°C, the tensile strength was 70 MPa, the elongation at break was 82%, and the T g The temperature is 117℃ and the number average molecular weight is 3×10 4 g / mol.

[0089] Example 6

[0090] A method for preparing an isohexide-based polycarbonate copolymer comprises the following steps:

[0091] (1) Preparation of raw materials;

[0092] Diol A1: isoidol;

[0093] Diol A2: Galx-OH;

[0094] Diol A3: 1,5-pentanediol;

[0095] Carbonate diester: diamyl carbonate;

[0096] Catalyst: potassium carbonate;

[0097] (2) preparing isohexide-based polycarbonate copolymers;

[0098] The diols (diol A1, diol A2, diol A3) and carbonic acid diester are subjected to transesterification reaction, preliminary polycondensation reaction, and final polycondensation reaction in sequence under the action of a catalyst to obtain an isohexide-based polycarbonate copolymer; wherein the molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.7:0.25:0.05:1.1, and the molar amount of the catalyst is 5×10 of the total molar amount of the diols. -4 ;

[0099] The transesterification reaction is carried out under nitrogen or inert gas protection, the temperature of the transesterification reaction is 160°C, the pressure is 0.1 MPa, and the time is 1.5 h;

[0100] During the pre-polycondensation reaction, the temperature was first gradually increased to 200°C within 8 minutes, and then the pressure was gradually reduced to 55 kPa within 5 minutes. Finally, a gradient temperature increase and gradient pressure reduction were performed, i.e., the temperature was maintained for 15 minutes each time the temperature was increased by 10°C, while the pressure was reduced by 5-10 kPa. The total time for the gradient temperature increase and gradient pressure reduction was 45 minutes. The termination conditions of the gradient temperature increase and gradient pressure reduction were: temperature 230°C and pressure 20 kPa;

[0101] The temperature of the final polycondensation reaction is 250°C, the pressure is 90 Pa, and the time is 1 hour.

[0102] The final isohexide-based polycarbonate copolymer had a thermal weight loss temperature of 5 wt% at 362°C, a tensile strength of 68 MPa, an elongation at break of 97%, and a T g The temperature is 113℃ and the number average molecular weight is 6×10 4 g / mol.

[0103] Example 7

[0104] A method for preparing an isohexide-based polycarbonate copolymer comprises the following steps:

[0105] (1) Preparation of raw materials;

[0106] Diol A1: isoidol;

[0107] Diol A2: Manx-OH;

[0108] Diol A3: 1,4-butanediol;

[0109] Carbonate diester: dioctyl carbonate;

[0110] Catalyst: rubidium carbonate;

[0111] (2) preparing isohexide-based polycarbonate copolymers;

[0112] The diols (diol A1, diol A2, diol A3) and carbonic acid diester are subjected to transesterification reaction, preliminary polycondensation reaction, and final polycondensation reaction in sequence under the action of a catalyst to obtain an isohexide-based polycarbonate copolymer; wherein the molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.7:0.2:0.1:1, and the molar amount of the catalyst is 2×10 of the total molar amount of the diols. -4 ;

[0113] The transesterification reaction is carried out under nitrogen or inert gas protection, the temperature of the transesterification reaction is 160°C, the pressure is 0.1 MPa, and the time is 1.5 h;

[0114] During the pre-polycondensation reaction, the temperature was first gradually increased to 200°C within 8 minutes, and then the pressure was gradually reduced to 55 kPa within 5 minutes. Finally, a gradient temperature increase and gradient pressure reduction were performed, i.e., the temperature was maintained for 15 minutes each time the temperature was increased by 10°C, while the pressure was reduced by 5-10 kPa. The total time for the gradient temperature increase and gradient pressure reduction was 45 minutes. The termination conditions of the gradient temperature increase and gradient pressure reduction were: temperature 230°C and pressure 20 kPa;

[0115] The temperature of the final polycondensation reaction is 250°C, the pressure is 120 Pa, and the time is 1 hour.

[0116] The thermal weight loss temperature of the isohexide-based polycarbonate copolymer finally obtained was 371°C, the tensile strength was 81 MPa, the elongation at break was 90%, and the T g is 126℃, and the number average molecular weight is 4×10 4 g / mol.

[0117] Example 8

[0118] A method for preparing an isohexide-based polycarbonate copolymer comprises the following steps:

[0119] (1) Preparation of raw materials;

[0120] Diol A1: isomannide;

[0121] Diol A2: BCD;

[0122] Diol A3: 1,6-hexanediol;

[0123] Carbonate diester: diethyl carbonate;

[0124] Catalyst: lithium hydroxide;

[0125] (2) preparing isohexide-based polycarbonate copolymers;

[0126] The diols (diol A1, diol A2, diol A3) and carbonic acid diester are subjected to transesterification reaction, preliminary polycondensation reaction, and final polycondensation reaction in sequence under the action of a catalyst to obtain an isohexide-based polycarbonate copolymer; wherein the molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.8:0.1:0.1:1, and the molar amount of the catalyst is 3×10 of the total molar amount of the diols. -4 ;

[0127] The transesterification reaction is carried out under nitrogen or inert gas protection, the temperature of the transesterification reaction is 150°C, the pressure is 0.1 MPa, and the time is 1.5 h;

[0128] During the pre-polycondensation reaction, the temperature is first gradually increased to 200°C within 10 minutes, and then the pressure is gradually reduced to 50 kPa within 5 minutes. Finally, a gradient temperature increase and gradient pressure reduction are performed, that is, the temperature is increased by 10°C for 20 minutes each time, and the pressure is reduced by 10-15 kPa at the same time. The total time for the gradient temperature increase and gradient pressure reduction is 60 minutes. The termination conditions of the gradient temperature increase and gradient pressure reduction are: temperature 230°C and pressure 15 kPa;

[0129] The temperature of the final polycondensation reaction is 240°C, the pressure is 130 Pa, and the time is 1 hour.

[0130] The final isohexide-based polycarbonate copolymer had a thermal weight loss temperature of 5 wt% at 345°C, a tensile strength of 80 MPa, an elongation at break of 79%, and a T g is 121℃, and the number average molecular weight is 5×10 4 g / mol.

[0131] Example 9

[0132] A method for preparing an isohexide-based polycarbonate copolymer is basically the same as that in Example 8, except that the diol A2 prepared in step (1) is CHD.

[0133] The final isohexide-based polycarbonate copolymer had a thermal weight loss temperature of 5 wt% at 355°C, a tensile strength of 70 MPa, an elongation at break of 93%, and a T g The temperature is 110℃ and the number average molecular weight is 3×10 4 g / mol.

[0134] Example 10

[0135] A method for preparing an isohexide-based polycarbonate copolymer comprises the following steps:

[0136] (1) Preparation of raw materials;

[0137] Diol A1: isosorbide;

[0138] Diol A2: CaG;

[0139] Diol A3: CBDO;

[0140] Carbonate diester: dimethyl carbonate;

[0141] Catalyst: lithium chloride;

[0142] (2) preparing isohexide-based polycarbonate copolymers;

[0143] The diols (diol A1, diol A2, diol A3) and carbonic acid diester are subjected to transesterification reaction, preliminary polycondensation reaction, and final polycondensation reaction in sequence under the action of a catalyst to obtain an isohexide-based polycarbonate copolymer; wherein the molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.6:0.3:0.1:1, and the molar amount of the catalyst is 1×10 of the total molar amount of the diols. -5 ;

[0144] The transesterification reaction is carried out under nitrogen or inert gas protection, the temperature of the transesterification reaction is 160°C, the pressure is 0.1 MPa, and the time is 1.5 h;

[0145] During the pre-polycondensation reaction, the temperature was first gradually increased to 190°C within 5 minutes, and then the pressure was gradually reduced to 47 kPa within 5 minutes. Finally, a gradient temperature increase and gradient pressure reduction were performed, i.e., the temperature was maintained for 10 minutes each time the temperature was increased by 10°C, while the pressure was reduced by 6-12 kPa. The total time for the gradient temperature increase and gradient pressure reduction was 30 minutes. The termination conditions of the gradient temperature increase and gradient pressure reduction were: temperature 220°C and pressure 20 kPa;

[0146] The final polycondensation reaction temperature was 230°C, the pressure was 80 Pa, and the time was 2 h.

[0147] The thermal weight loss temperature of the isohexide-based polycarbonate copolymer finally obtained was 350°C, the tensile strength was 82 MPa, the elongation at break was 60%, and the T g is 127℃, and the number average molecular weight is 4×10 4 g / mol.

[0148] Comparative Example 2

[0149] A method for preparing an isohexide-based polycarbonate copolymer is basically the same as Example 10, except that the molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.4:0.5:0.1:1.

[0150] The thermal weight loss temperature of the isohexide-based polycarbonate copolymer finally obtained was 340°C, the tensile strength was 52 MPa, the elongation at break was 95%, and the T g is 99℃, and the number average molecular weight is 4×10 4 g / mol.

[0151] By comparing Example 10 with Comparative Example 2, it can be seen that since the proportion of diol A2 in Comparative Example 2 is greater than the proportion of diol A1, the heat resistance and strength of the obtained isohexide-based polycarbonate copolymer will be reduced. This is because diol A1 is the main rigidity provider, and A2 is a monomer with a rigid and flexible structure and is also the main provider of toughness. If the proportion of diol A1 is too low, the obtained copolymer will not have sufficient rigidity to provide high heat resistance and high strength properties.

[0152] Comparative Example 3

[0153] A method for preparing an isohexide-based polycarbonate copolymer is basically the same as Example 10, except that the molar ratio of diol A1, diol A2, diol A3 and carbonate diester is 0.85:0.05:0.1:1.

[0154] The final isohexide-based polycarbonate copolymer had a thermal weight loss temperature of 5 wt% of 349 ° C, a tensile strength of 68 MPa, an elongation at break of 30%, and a T g At 150 °C, the number average molecular weight is 2.9×10 4 g / mol.

[0155] By comparing Example 10 with Comparative Example 3, it can be seen that since the proportion of diol A1 in Comparative Example 3 is too large and the proportion of diol A2 is too small, the molecular weight of the obtained copolymer will be reduced, the toughness will deteriorate, and the material will become brittle. This is because diol A1 is the main provider of rigidity and A2 is the main provider of toughness. When the proportion of diol A1 is too large, the rigidity of the obtained copolymer will be too strong and the toughness will deteriorate. Moreover, since diol A1 is a secondary alcohol and its reaction activity is lower than that of a primary alcohol, when the content of diol A1 is too high, the molecular weight of the polymer will also decrease.

[0156] Example 11

[0157] A method for preparing an isohexide-based polycarbonate copolymer is basically the same as Example 10, except that: diol A3 is not prepared in step (1); and in step (2), the molar ratio of diol A1, diol A2 and carbonate diester is 0.6:0.4:1.

[0158] The final isohexide-based polycarbonate copolymer had a thermal weight loss temperature of 5 wt% at 345°C, a tensile strength of 75 MPa, an elongation at break of 80%, and a T g The temperature is 125℃ and the number average molecular weight is 4.5×10 4 g / mol.

[0159] Example 12

[0160] A method for preparing an isohexide-based polycarbonate copolymer comprises the following steps:

[0161] (1) Preparation of raw materials;

[0162] Diol A1: isoidol;

[0163] Diol A2: CM diol;

[0164] Diol A3: ethylene glycol;

[0165] Carbonate diester: dibutyl carbonate;

[0166] Catalyst: sodium chloride;

[0167] (2) preparing isohexide-based polycarbonate copolymers;

[0168] The diols (diol A1, diol A2, diol A3) and carbonic acid diester are subjected to transesterification reaction, preliminary polycondensation reaction, and final polycondensation reaction in sequence under the action of a catalyst to obtain an isohexide-based polycarbonate copolymer; wherein the molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.7:0.2:0.1:1, and the molar amount of the catalyst is 5×10 of the total molar amount of the diols. -4 ;

[0169] The transesterification reaction is carried out under nitrogen or inert gas protection, the temperature of the transesterification reaction is 120°C, the pressure is 0.1 MPa, and the time is 4 hours;

[0170] During the pre-polycondensation reaction, the temperature was first gradually increased to 180°C within 15 minutes, and then the pressure was gradually reduced to 45 kPa within 5 minutes. Finally, a gradient temperature increase and gradient pressure reduction were performed, i.e., the temperature was maintained for 20 minutes each time the temperature was increased by 10°C, while the pressure was reduced by 3-7 kPa. The total time for the gradient temperature increase and gradient pressure reduction was 60 minutes. The termination conditions of the gradient temperature increase and gradient pressure reduction were: temperature 210°C and pressure 30 kPa.

[0171] The temperature of the final polycondensation reaction is 250°C, the pressure is 90 Pa, and the time is 0.5 h.

[0172] The final isohexide-based polycarbonate copolymer had a thermal weight loss temperature of 5 wt% at 345°C, a tensile strength of 65 MPa, an elongation at break of 76%, and a T g At 120 °C, the number average molecular weight is 5×10 4 g / mol.

[0173] Example 13

[0174] A method for preparing an isohexide-based polycarbonate copolymer is basically the same as Example 12, except that diol A3 is not prepared; and the molar ratio of diol A1, diol A2 and carbonate diester in step (2) is 0.7:0.3:1.

[0175] The final isohexide-based polycarbonate copolymer had a thermal weight loss of 5 wt% at 470°C, a tensile strength of 71 MPa, an elongation at break of 80%, and a T g The temperature is 127℃ and the number average molecular weight is 3×10 4 g / mol.

[0176] Example 14

[0177] A method for preparing an isohexide-based polycarbonate copolymer comprises the following steps:

[0178] (1) Preparation of raw materials;

[0179] Diol A1: a mixture of isosorbide and isomannide in a mass ratio of 13:1;

[0180] Diol A2: a mixture of IIDML and tetrahydrofuran dimethanol in a mass ratio of 1:1;

[0181] Carbonate diester: a mixture of diethyl carbonate and dibutyl carbonate in a mass ratio of 1:1;

[0182] Catalyst: potassium hydroxide;

[0183] (2) preparing isohexide-based polycarbonate copolymers;

[0184] The diols (diol A1, diol A2) and carbonic acid diester are subjected to transesterification reaction, preliminary polycondensation reaction and final polycondensation reaction in sequence under the action of a catalyst to obtain an isohexide-based polycarbonate copolymer; wherein the molar ratio of diol A1, diol A2 and carbonic acid diester is 0.6:0.4:1.1, and the molar amount of the catalyst is 4×10 of the total molar amount of the diols. -4 ;

[0185] The transesterification reaction was carried out under nitrogen or inert gas protection at a temperature of 130°C, a pressure of 0.1 MPa, and a time of 3 h.

[0186] During the pre-polycondensation reaction, the temperature was first gradually increased to 190°C within 15 minutes, and then the pressure was gradually reduced to 50 kPa within 5 minutes. Finally, a gradient temperature increase and a gradient pressure decrease were performed, i.e., the temperature was increased by 10°C for 20 minutes, and the pressure was reduced by 5-15 kPa. The total time for the gradient temperature increase and the gradient pressure decrease was 60 minutes. The termination conditions of the gradient temperature increase and the gradient pressure decrease were: temperature 220°C and pressure 25 kPa.

[0187] The final polycondensation reaction temperature was 240°C, the pressure was 100 Pa, and the time was 80 min.

[0188] The thermal weight loss temperature of the isohexide-based polycarbonate copolymer finally obtained was 350°C, the tensile strength was 72 MPa, the elongation at break was 110%, and the T g The temperature is 115℃ and the number average molecular weight is 9×10 4 g / mol.

[0189] Example 15

[0190] A method for preparing an isohexide-based polycarbonate copolymer comprises the following steps:

[0191] (1) Preparation of raw materials;

[0192] Diol A1: a mixture of isoidol and isomannide in a mass ratio of 1:1;

[0193] Diol A2: a mixture of IIDML and tetrahydrofuran dimethanol in a mass ratio of 1:1;

[0194] Diol A3: a mixture of CHDM and ethylene glycol in a mass ratio of 1:2;

[0195] Carbonate diester: a mixture of diethyl carbonate and dibutyl carbonate in a mass ratio of 1:1;

[0196] Catalyst: potassium hydroxide;

[0197] (2) preparing isohexide-based polycarbonate copolymers;

[0198] The diols (diol A1, diol A2, diol A3) and carbonic acid diester are subjected to transesterification reaction, preliminary polycondensation reaction, and final polycondensation reaction in sequence under the action of a catalyst to obtain an isohexide-based polycarbonate copolymer; wherein the molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.6:0.2:0.2:1.1, and the molar amount of the catalyst is 4×10 of the total molar amount of the diols. -4 ;

[0199] The transesterification reaction was carried out under nitrogen or inert gas protection at a temperature of 130°C, a pressure of 0.1 MPa, and a time of 3 h.

[0200] During the pre-polycondensation reaction, the temperature was first gradually increased to 190°C within 15 minutes, and then the pressure was gradually reduced to 50 kPa within 5 minutes. Finally, a gradient temperature increase and a gradient pressure decrease were performed, i.e., the temperature was increased by 10°C for 20 minutes, and the pressure was reduced by 5-15 kPa. The total time for the gradient temperature increase and the gradient pressure decrease was 60 minutes. The termination conditions of the gradient temperature increase and the gradient pressure decrease were: temperature 220°C and pressure 25 kPa.

[0201] The final polycondensation reaction temperature was 240°C, the pressure was 100 Pa, and the time was 80 min.

[0202] The final isohexide-based polycarbonate copolymer had a thermal weight loss temperature of 5 wt% at 345°C, a tensile strength of 70 MPa, an elongation at break of 103%, and a T g The temperature is 113℃ and the number average molecular weight is 8×10 4 g / mol.

Claims

1. A method for preparing an isohexide-based polycarbonate copolymer, characterized in that: The diol and the carbonate diester are subjected to an ester exchange reaction, a preliminary polycondensation reaction, and a final polycondensation reaction in sequence under the action of a catalyst to obtain an isohexide-based polycarbonate copolymer; The diol includes diol A1 and diol A2, or further includes diol A3; Diol A1 is isohexitol; The molecular structure of diol A2 contains a cyclic ether structure and two primary hydroxyl groups, and the primary hydroxyl group and the cyclic ether structure are connected by a methylene group; Diol A3 is a dihydroxy compound; The molar ratio of diol A1, diol A2, diol A3 and carbonic acid diester is 0.6-0.8:0.1-0.4:0-0.2:1-1.1; During the pre-polycondensation reaction, the temperature is first gradually increased to 180-200°C within 5-15 minutes, and then the pressure is gradually reduced to 45-55kPa within 5 minutes. Finally, gradient temperature increase and gradient pressure reduction are performed, that is, each temperature increase of 10°C is maintained for 10-20 minutes, and the pressure is reduced by 3-15kPa at the same time. The total time for gradient temperature increase and gradient pressure reduction is 0.5-1h. The termination conditions of gradient temperature increase and gradient pressure reduction are: temperature of 210-230°C and pressure of 15-30kPa.

2. The method for preparing an isohexide-based polycarbonate copolymer according to claim 1, wherein: The thermal weight loss of isohexide-based polycarbonate copolymer is 5wt% at a temperature of ≥345°C, the tensile strength is 65-85MPa, the elongation at break is 60%-110%, and the T g ≥110℃, number average molecular weight is 3×10 4 -13×10 4 g / mol.

3. The method for preparing an isohexide-based polycarbonate copolymer according to claim 1, wherein: The diol A1 is one or more of isosorbide, isomannide and isoidide.

4. The method for preparing an isohexide-based polycarbonate copolymer according to claim 1, wherein: The diol A2 is one or more of IIDML, IMDML, ISDML, tetrahydrofuran dimethanol, furan dimethanol, Galx-OH, Manx-OH, BCD, CHD, CaG, and CM diol.

5. The method for preparing an isohexide-based polycarbonate copolymer according to claim 1, wherein: The diol A3 is one or more of CHDM, CBDO, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

6. The method for preparing an isohexide-based polycarbonate copolymer according to claim 1, wherein: The carbonic acid diester is one or more of diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, dipentyl carbonate, and dioctyl carbonate.

7. The method for preparing an isohexide-based polycarbonate copolymer according to claim 1, wherein: The catalyst is a metal catalyst.

8. The method for preparing an isohexide-based polycarbonate copolymer according to claim 1, wherein: The molar amount of the catalyst is 1×10 of the total molar amount of the diol. -5 -5×10 -4 .

9. The method for preparing an isohexide-based polycarbonate copolymer according to claim 1, wherein: The transesterification reaction is carried out under the protection of nitrogen or inert gas, the temperature of the transesterification reaction is 120-160°C, the pressure is 0.1MPa, and the time is 1.5-4h; the temperature of the final polycondensation reaction is 230-250°C, the pressure is below 150Pa, and the time is 0.5-2h.

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