High molecular weight polybutylene terephthalate carbonates based on carbon dioxide and method for their production

Abstract

The application belongs to the technical field of carbon dioxide conversion and polymer synthesis, and particularly relates to a kind of high molecular weight poly-carbonate-terephthalate-butylene glycol based on carbon dioxide polycondensation and a preparation method thereof. The application adopts carbon dioxide and 1,4-butylene glycol dehydration polycondensation to prepare a polycarbonate oligomer, and then connects a melt polycondensation process and terephthalic acid dibutylene glycol copolymerization in series to prepare high molecular weight poly-carbonate-terephthalate-butylene glycol. The method directly uses carbon dioxide and terephthalic acid as monomers, avoids using carbonic acid diester and terephthalic acid dimethyl ester, greatly shortens the production process and effectively improves the carbon dioxide utilization rate. The process is simple, the cost is low, the product molecular weight is controllable, the production can be scaled up, and the method has excellent industrialization prospect. At the same time, carbon dioxide, a carbon resource, is effectively converted in the synthesis of the polymer, which has important promoting significance for the realization of the carbon neutralization strategy.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of carbon dioxide conversion and polymer synthesis, and particularly relates to a kind of high molecular weight poly-carbonate-terephthalic acid-butylene glycol ester based on carbon dioxide polycondensation and a preparation method thereof. BACKGROUND

[0002] With the increasing consumption of unsustainable resources such as oil, the carbon emissions of its downstream industries are increasing day by day. At the same time, as one of the bulk conversion products of petrochemical resources, polymers have become a major threat to the environment due to the non-degradability of most varieties, and the white pollution problem has also become a major threat to the current environment. Therefore, reducing carbon emissions and eliminating white pollution have become obstacles that must be overcome in the upgrading of the chemical industry, especially the polymer industry. In this regard, many polymers prepared from carbon dioxide as raw material have been reported and even commercialized, which has played an important role in promoting the current "double carbon" policy and sustainable development strategy.

[0003] Poly-carbonate-terephthalic acid-butylene glycol ester (PBCT) is a polyester carbonate copolymer with excellent comprehensive performance. Similar to the current mainstream commercial degradable polyester, polybutylene adipate terephthalate (PBAT), the presence of aliphatic polycarbonate units in the polymer chain gives the polymer excellent degradability and flexibility. Compared with PBAT, PBCT has higher barrier properties and lower cost advantages, and the carbonate segment can be introduced from carbon dioxide chemical conversion products, such as dimethyl carbonate (DMC) or diphenyl carbonate (DPC). Vigorously developing this new type of polymer market, PBCT, meets the demand for promoting degradable plastics.

[0004] Patent publication No. CN103265689A introduces aromatic monomers such as terephthalic acid and isophthalic acid into the polycarbonate backbone, and an excellent aromatic-aliphatic polycarbonate copolymer is prepared by a step-by-step esterification method. Patent publication No. CN115873223A discloses a method for preparing PBCT from DMC, dimethyl terephthalate, and 1,4-butanediol (BDO) under a composite catalyst, with a polymer intrinsic viscosity of 1.2-2.0 dL / g, and a shortened final condensation time and improved production efficiency. However, the carbonate carbon source in the PBCT polymer chain prepared by the above patent applications is derived from DMC or DPC, which has a high dependence on epoxy-based raw monomers, and the process flow from carbon dioxide to polymer is relatively long. If the polycarbonate units are obtained directly from carbon dioxide and diols, the PBCT production process can be significantly shortened, and the utilization rate of carbon dioxide can be effectively improved. Therefore, how to reduce the high dependence of PBCT on epoxy-based raw monomers and the long production process, while improving the utilization rate of carbon dioxide, is a technical problem that needs to be solved. SUMMARY

[0005] In order to solve the technical problems of the existing PBCT preparation process, such as relying on epoxy raw material monomers, high cost of catalyst, harsh reaction conditions, and difficult to scale production, the application provides a kind of high molecular weight poly-carbonate-terephthalate-butylene glycol based on carbon dioxide polycondensation and a preparation method thereof. The application uses carbon dioxide and aliphatic diols to prepare polycarbonate oligomers by dehydration polycondensation, and then uses a series of melt polycondensation process and terephthalic acid dibutylene glycol copolymerization to prepare high molecular weight poly-carbonate-terephthalate-butylene glycol PBCT.

[0006] The method directly uses carbon dioxide and terephthalic acid (PTA) as monomers, avoids the use of carbonic acid diester and terephthalic acid dimethyl ester, greatly shortens the production process of PBCT and effectively improves the utilization rate of carbon dioxide. The method does not need to use epoxy raw material monomers, has simple process and low cost, the molecular weight of the product is controllable, can be produced on a large scale, and has excellent industrialization prospect.

[0007] In the first aspect, the application provides a kind of high molecular weight poly-carbonate-terephthalate-butylene glycol based on carbon dioxide polycondensation, and the high molecular weight poly-carbonate-terephthalate-butylene glycol is random copolymer of terephthalic acid dibutylene glycol block and oligomeric carbonate block, and the structural formula is as follows:

[0008] ;

[0009] Wherein, x and y are natural numbers, and x:y=1-9900:100.

[0010] Further, the intrinsic viscosity of the high molecular weight poly-carbonate-terephthalate-butylene glycol is 1.2-2.0 dL / g.

[0011] Further, x:y=3:7-7:3.

[0012] In the second aspect, the application provides a kind of preparation method of high molecular weight poly-carbonate-terephthalate-butylene glycol based on carbon dioxide polycondensation. Under the action of organic base catalyst and condensing agent, carbon dioxide and 1,4-butylene glycol are dehydrated and polycondensed to obtain oligomeric carbonate; under the action of melt copolymerization catalyst, the oligomeric carbonate and terephthalic acid dibutylene glycol are melt copolycondensed to obtain the high molecular weight poly-carbonate-terephthalate-butylene glycol.

[0013] Further, the terephthalic acid dibutylene glycol is obtained by esterification reaction of 1,4-butylene glycol and terephthalic acid under the condition of esterification catalyst.

[0014] Further, the organic base catalyst is at least one selected from N,N,N',N'-tetramethylethylenediamine (TMEDA), 4-dimethylaminopyridine (DMAP), 4-pyrrolidinopyridine (PPY), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), 1,1,3,3-tetramethylguanidine (TMG), 2-tert-butyl-1,1,3,3-tetramethylguanidine (t-Bu-TMG), preferably DBU, MTBD and t-Bu-TMG.

[0015] Further, the condensation agent is at least one selected from dicyclohexyl carbodiimide and diisopropyl carbodiimide, preferably diisopropyl carbodiimide.

[0016] Further, the esterification catalyst is at least one selected from magnesium acetate, zinc acetate, antimony trioxide, germanium dioxide, diethylenediamine titanate, tetra-t-butyl titanate, tetrabutyl titanate and tetraisopropyl titanate, preferably tetrabutyl titanate.

[0017] Further, the melt copolymerization catalyst is at least one selected from sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, lithium acetylacetonate, zirconium acetylacetonate and cesium carbonate, preferably sodium methoxide.

[0018] Further, the mass ratio of the oligomeric carbonate and the melt copolymerization catalyst is 1: (0.0005-0.005).

[0019] Further, the specific preparation steps are as follows:

[0020] R1, 1,4-butanediol, an organic base catalyst and a condensation agent are put into an autoclave, heated to 130℃ under a carbon dioxide atmosphere at 1 MPa for dehydration and polycondensation, reacted for 6-24 h, and then treated to obtain an oligomeric carbonate;

[0021] R2, the oligomeric carbonate, terephthalic acid dibutylene glycol ester and a melt copolymerization catalyst are put into an autoclave, heated and reacted under a nitrogen atmosphere and mechanical stirring to obtain a high molecular weight poly-carbonate-terephthalic acid-butylene glycol ester.

[0022] Further, the post-treatment method of step R1 is as follows: after the reaction, an appropriate amount of solvent is added at -20-0℃ to fully dissolve the oligomer, filtered, washed with acid, dried, rotary evaporated and vacuum dried.

[0023] Further, in the step R2, the co-esterification reaction is first carried out at normal pressure by heating to a first temperature for 1-3 hours, and then the melt polycondensation is carried out by slowly heating to a second temperature under reduced pressure of 10-50 Pa for 4-8 hours; the first temperature is 140-180 DEG C, and the second temperature is 220-280 DEG C.

[0024] Further, the preparation method of the terephthalic acid dibutylene ester is as follows: the terephthalic acid, 1,4-butanediol and esterification catalyst are put into a reactor, and heated to 230-250 DEG C under nitrogen atmosphere for 2-4 hours to obtain the terephthalic acid dibutylene ester.

[0025] Beneficial effects:

[0026] The present application provides a high molecular weight poly-carbonate-terephthalate-butanediol ester and a preparation method thereof, which uses carbon dioxide as a direct polymerization monomer, meets the carbon neutralization strategy requirement and does not depend on DMC or DPC in the traditional method. Meanwhile, the process of carbon dioxide prepolymer melt polycondensation series can ensure that the polyester carbonate has a high enough molecular weight, and can also be applied to the existing production equipment and technology, is easy to scale, and has important significance in environmental protection and economic value. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The synthesis route of the high molecular weight poly-carbonate-terephthalate-butanediol ester;

[0028] Figure 2 The high molecular weight poly-carbonate-terephthalate-butanediol ester in Example 4; 1 H-NMR chart. DETAILED DESCRIPTION

[0029] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the schemes of the present application will be further described below. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0030] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other different ways from those described herein; obviously, the embodiments in the description are only a part of the embodiments of the present application, rather than all the embodiments.

[0031] The preferred embodiments of the present application will be described in detail below with reference to the embodiments. It should be understood that the following embodiments are given only for the purpose of illustration, and are not used to limit the scope of the present application. Those skilled in the art can make various modifications and replacements to the present application without departing from the spirit and principles of the present application.

[0032] Test instrument model: The model of the nuclear magnetic resonance spectrometer used was Varian DLG400 (Varian, USA).

[0033] Example 1 (Preparation of oligomeric butylene carbonate)

[0034] 4.506 g of 1,4-butanediol (50 mmol), 0.0761 g of DBU (0.5 mmol), and 5.679 g of diisopropyl carbodiimide (45 mmol) were placed in an autoclave, which was pressurized with high-purity carbon dioxide to 1 MPa, and the pressure was released to normal pressure three times. Subsequently, the autoclave was pressurized with carbon dioxide to 1 MPa, and heated to 130°C for 24 h. After cooling to room temperature, the pressure was released, and 15 mL of dichloromethane was added to the system. The filtrate was washed with 10 mL of 1.0 M hydrochloric acid and 10 mL of deionized water, respectively, and dried over anhydrous magnesium sulfate. After filtration, rotary evaporation, and vacuum drying at 50°C for 12 h, oligomeric butylene carbonate (PBC) was obtained.

[0035] Example 2 (Preparation of dibutylene terephthalate)

[0036] 16.613 g of PTA (0.1 mol), 19.826 g of BDO (0.22 mol), and 0.0166 g of tetrabutyl titanate were placed in a reactor, and the system was heated to 230°C for 2 h under a nitrogen atmosphere until it became clear. After cooling to room temperature, dibutylene terephthalate was obtained.

[0037] Example 3 (Preparation of PBCT by melt copolycondensation: molar ratio of PBT units to PBC units is 3:7)

[0038] 9.31 g of dibutylene terephthalate (30 mmol), 8.128 g of oligomeric PBC (70 mmol of PBC units), and 0.0081 g of sodium methoxide were placed in a three-necked flask, which was replaced with a nitrogen atmosphere three times. Subsequently, the system was heated to 160°C and co-esterified under mechanical stirring for 2 h. The pressure of the system was slowly reduced to about 30 Pa, and then the temperature was slowly increased to 230°C and reacted for 6 h to obtain high-molecular-weight PBCT. The intrinsic viscosity was 1.27 dL / g.

[0039] Example 4 (Preparation of PBCT by melt copolycondensation: molar ratio of PBT units to PBC units is 5:5)

[0040] Into a three-necked flask, 15.518 g of dibutylene terephthalate (50 mmol), 5.806 g of oligomer PBC (PBC unit 50 mmol) and 0.0058 g of sodium methoxide were put, the nitrogen atmosphere was replaced for three times, then heated to 160℃ and co-esterified for 2 h under mechanical stirring, the system pressure was slowly reduced to about 30 Pa, then slowly heated to 230℃ and reacted for 6 h to obtain high molecular weight PBCT; the intrinsic viscosity was 1.39 dL / g.

[0041] Example 5 (preparation of PBCT by melt co-condensation: the molar ratio of PBT unit to PBC unit was 7:3)

[0042] Into a three-necked flask, 21.723 g of dibutylene terephthalate (70 mmol), 3.484 g of oligomer PBC (PBC unit 30 mmol) and 0.0035 g of sodium methoxide were put, the nitrogen atmosphere was replaced for three times, then heated to 160℃ and co-esterified for 2 h under mechanical stirring, the system pressure was slowly reduced to about 30 Pa, then slowly heated to 230℃ and reacted for 6 h to obtain high molecular weight PBCT; the intrinsic viscosity was 1.68 dL / g.

[0043] The above are only preferred embodiments of the present application, and do not limit the protection scope of the present application, any equivalent structure or equivalent flow transformation made by the present application, or directly or indirectly used in other related technical fields, are also included in the protection scope of the present application.

Claims

1. A method for preparing high molecular weight polybutylene terephthalate based on carbon dioxide condensation, characterized in that, In the presence of an organic base catalyst and a condensing agent, carbon dioxide and 1,4-butanediol undergo dehydration condensation to obtain oligocarbonate; in the presence of a melt copolymerization catalyst, the oligocarbonate and dibutyl terephthalate undergo melt copolymerization to obtain the high molecular weight polycarbonate-butyl terephthalate based on carbon dioxide condensation. The organic base catalyst is selected from at least one of N,N,N',N'-tetramethylethylenediamine, 4-dimethylaminopyridine, 4-pyrrolylpyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]decen-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,1,3,3-tetramethylguanidine, and 2-tert-butyl-1,1,3,3-tetramethylguanidine; The condensing agent is at least one of dicyclohexylcarbodiimide and diisopropylcarbodiimide.

2. The method for preparing high molecular weight polycarbonate-butylene terephthalate based on carbon dioxide condensation according to claim 1, characterized in that, The melt copolymerization catalyst is selected from at least one of sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, lithium acetylacetonate, zirconium acetylacetonate, and cesium carbonate.

3. The method for preparing high molecular weight polycarbonate-butylene terephthalate based on carbon dioxide condensation according to claim 2, characterized in that, The mass ratio of the oligocarbonate to the melt copolymerization catalyst is 1:(0.0005-0.005).

4. The method for preparing high molecular weight polycarbonate-butylene terephthalate based on carbon dioxide polycondensation according to claim 1, characterized in that, The dibutyl terephthalate is obtained by esterification reaction of 1,4-butanediol with terephthalate under esterification catalyst conditions.

5. The method for preparing high molecular weight polycarbonate-butylene terephthalate based on carbon dioxide condensation according to claim 4, characterized in that, The esterification catalyst is selected from at least one of magnesium acetate, zinc acetate, antimony trioxide, germanium dioxide, diethylene titanate, tetrabutyl titanate, and tetraisopropyl titanate.

6. The method for preparing high molecular weight polycarbonate-butylene terephthalate based on carbon dioxide condensation according to claim 3, characterized in that, Includes the following steps: R1. 1,4-Butanediol, organic base catalyst and condensing agent are added to a pressure vessel and heated to 130°C in a carbon dioxide atmosphere at 1 MPa for dehydration polycondensation. The reaction is carried out for 6-24 hours and then post-processed to obtain oligocarbonate. R2. Oligocarbonate, dibutyl terephthalate and melt copolymerization catalyst are placed in a pressure vessel and heated under nitrogen atmosphere and mechanical stirring to obtain high molecular weight polycarbonate-butyl terephthalate based on carbon dioxide condensation.

7. The method for preparing high molecular weight polycarbonate-butylene terephthalate based on carbon dioxide condensation according to claim 6, characterized in that, The post-processing method of step R1 is as follows: after the reaction is completed, add an appropriate amount of solvent at -20-0℃ to fully dissolve the oligomers, filter, and wash the filtrate with acid, dry, rotary evaporate and vacuum dry.

8. The method for preparing high molecular weight polybutylene terephthalate based on carbon dioxide condensation according to claim 6, characterized in that, In step R2, the reaction is first carried out by heating to a first temperature under normal pressure for 1-3 hours to perform a coesterification reaction, and then slowly heating to a second temperature and depressurizing to 10-50 Pa to perform melt polycondensation for 4-8 hours; the first temperature is 140-180℃ and the second temperature is 220-280℃.

9. The method for preparing high molecular weight polycarbonate-butylene terephthalate based on carbon dioxide polycondensation according to any one of claims 1-8, characterized in that, The intrinsic viscosity of the prepared high molecular weight polycarbonate-butylene terephthalate is 1.2-2.0 dL / g.

10. The method for preparing high molecular weight polycarbonate-butylene terephthalate based on carbon dioxide polycondensation according to any one of claims 1-8, characterized in that, The high molecular weight polycarbonate-butylene terephthalate is a random copolymer of dibutylene terephthalate blocks and oligocarbonate blocks, with the following structural formula: ； Where x and y are both natural numbers, and x:y = 1-9900:100.

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