Preparation method of carbon dioxide-based polycarbonate polyol

Abstract

The invention relates to the technical field of polycarbonate polyols, and discloses a preparation method of carbon dioxide-based polycarbonate polyols, which comprises the following steps: adding an epoxy compound, a carborane derivative catalyst, a chain initiator and a chain transfer agent into a reactor, introducing carbon dioxide to replace air in the reactor, and reacting to obtain the carbon dioxide-based polycarbonate polyols. Then pressurizing, heating and stirring to carry out polymerization reaction, adding acid to terminate the reaction after the reaction is completed, and then purifying and drying to obtain the polycarbonate polyol, wherein the carborane derivative catalyst is prepared by the following preparation method: adding different substituted alkynes, decaborane, ethyl sulfide and toluene into a reaction flask in proportion in a nitrogen atmosphere, sealing the reaction flask, and heating and stirring to enable the decaborane to react with the different substituted alkynes. According to the method, a specific catalyst is used for replacing a traditional catalyst, and the reaction efficiency and the product molecular weight can be improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of polycarbonate polyol preparation, and particularly relates to a preparation method of carbon dioxide-based polycarbonate polyol. BACKGROUND

[0002] Carbon dioxide is a major greenhouse gas. With the acceleration of industrialization, its emission has increased sharply, which has a significant impact on the global climate. At the same time, carbon dioxide is a widely available, low-cost, non-toxic and renewable resource. Therefore, how to realize its efficient conversion and utilization has become the focus of many researchers.

[0003] Among the many utilization approaches, the synthesis of degradable aliphatic polycarbonate polyols from carbon dioxide and epoxide compounds through copolymerization is considered to be a promising technical route. Such materials have been widely used in many high-end fields, including new polyurethane materials, biomedical materials, gas barrier films, battery electrolytes, phase change materials, adhesives, photoresists, composites and rubber reinforcing agents, etc., and have shown good application potential and market value. Simply put, it is to make carbon dioxide and epoxide compounds copolymerize under the help of a specific catalyst to generate a polymer chain containing carbonate bonds.

[0004] The fundamental task of the catalyst is to efficiently and selectively catalyze the copolymerization of carbon dioxide and epoxide compounds (such as propylene oxide) to generate polycarbonate polyols with controllable molecular weight, regular sequence structure and hydroxyl end groups. Among them, the rare earth ternary complex catalyst, which is composed of a carboxylate or complex of a rare earth element (such as neodymium Nd, yttrium Y, etc.) as a main catalyst, an alkyl aluminum (such as triisobutyl aluminum) and a proton donor (such as glycerol, phosphoric acid, etc.), has the advantages of high activity, controllable product molecular weight, etc. However, it is also limited by its sensitivity to water and metal residue problems.

[0005] Triethylboron is a new catalyst with extremely high activity and reaction rate, and relatively high tolerance to water and proton-containing impurities, and has the characteristics of no metal, which has begun to gradually replace the above-mentioned rare earth ternary complex catalyst. However, it still restricts its development due to its high cost, poor thermal stability and self-ignition problems.

[0006] Therefore, the development of new catalysts to realize the efficient synthesis of carbon dioxide-based polycarbonate polyols not only has important scientific research value, but also has broad market application prospects, and is still a research hotspot in the field. SUMMARY

[0007] The carbon borane compound synthesized by reacting different substituted alkyne compounds with decaborane is used as a catalyst to replace the traditional catalyst, and cooperates with an initiator to form a catalytic system; the catalyst system used in the application significantly improves the copolymerization reaction rate, and can efficiently prepare polycarbonate polyols under similar feeding conditions, and effectively shortens the reaction time and improves the overall reaction efficiency. Meanwhile, the preparation method of the application avoids the use of metal catalysts, eliminates the problem of metal residues, and the synthesis route is green and mild. The carbon dioxide-based polycarbonate polyols prepared can be widely used in the manufacture of new polyurethane materials, biomedical materials, gas barrier films, battery electrolytes, phase change materials, adhesives, photoresists, and composite materials.

[0008] The application adopts the following technical solutions: A preparation method of a carbon dioxide-based polycarbonate polyol, comprising the following steps: An epoxy compound, a carbon borane derivative catalyst, a chain initiator and a chain transfer agent are added to a reactor, carbon dioxide is introduced to replace the air in the reactor, and then the reactor is pressurized, heated and stirred to perform a polymerization reaction. After the reaction is completed, an acid is added to terminate the reaction, and then purification and drying are performed to obtain the polycarbonate polyol. The carbon borane derivative catalyst is prepared by the following method: different substituted alkyne, decaborane, ethyl sulfide and toluene are added to a reaction bottle in proportion under a nitrogen atmosphere, the reaction bottle is sealed and heated and stirred to react decaborane with different substituted alkyne; after the reaction is completed, toluene is removed by reduced pressure distillation, and then recrystallization, filtration and drying are performed to obtain the carbon borane derivative catalyst.

[0009] By using the above technical solutions, under the activation of the carbon borane derivative catalyst of the application, the C-O bond of the epoxy group is opened and CO2 is inserted to form a carbonate bond to constitute the basic structure of the polymer main chain. By cooperating with the chain initiator, the epoxy compound and carbon dioxide are activated to reduce the reaction energy barrier and promote them to occur copolymerization reaction efficiently and selectively. The carbon borane derivative catalyst prepared by the application has high activity and stability, and does not contain metal substances, reducing the problem of metal residues.

[0010] Optionally, in the preparation method of the carbon borane derivative catalyst, the molar ratio of different substituted alkyne, decaborane, ethyl sulfide and toluene is (1-1.2):(1.5-1.8):(9-9.3):(100-102).

[0011] By adopting the technical scheme, the carbon borane derivative prepared by controlling the molar amount of each component has the characteristics of high stability, strong electron-donating property and large volume, so that it can form an excellent catalyst with high activity, high selectivity and good thermal stability for the copolymerization of CO2 and an epoxide compound in a catalytic reaction. The molar ratio of different substituted acetylenes, decaborane, ethyl sulfide and toluene is any point value in the above interval, such as 1:1.5:9:100.

[0012] Optionally, in the preparation method of the carbon borane derivative catalyst, the reaction temperature is 80-140℃.

[0013] By adopting the technical scheme, the reaction system is provided with sufficient energy by controlling the reaction temperature, so that a large number of reactant molecules can cross the energy barrier to react at a reasonable rate.

[0014] Optionally, the different substituted acetylenes are selected from one of acetylene, diphenylacetylene, p-methoxydiphenylacetylene and di-tert-butylacetylene.

[0015] By adopting the technical scheme, these acetylenes have the common characteristic of having two identical substituents, which makes the generated carbon borane symmetrical and more regular in structure, facilitating analysis and crystallization.

[0016] Optionally, in the preparation step of the polycarbonate polyol, the chain initiator is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium fluoride, potassium fluoride, cesium carbonate, cesium fluoride, triethylamine, pyridine, triethylenediamine, 4-dimethylaminopyridine, N,N-diisopropylethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, bis(triphenylphosphine)ammonium chloride, potassium tert-butoxide, sodium tert-butoxide, and sodium ethoxide.

[0017] Optionally, the molar ratio of the carbon borane derivative catalyst to the chain initiator is 1:0.5-1:10.

[0018] By adopting the technical scheme, the molar ratio of the carbon borane derivative catalyst to the chain initiator can be 1:0.5, 1:1, 1:2, 1:3, 1:5, 1:6, 1:10, etc.

[0019] Optionally, the molar ratio of the epoxide compound to the carbon borane derivative catalyst is 1000:1-4000:1.

[0020] Optionally, the molar ratio of the epoxide compound to the chain transfer agent is 2000:1-2000:20.

[0021] By adopting the technical scheme, the polycarbonate polyol product with controllable molecular weight and uniform distribution can be obtained by limiting the amount of each component.

[0022] Optionally, the chain transfer agent is a polyol or a polycarboxylic acid with a functionality of not less than 2.

[0023] By adopting the technical scheme, the polycarbonate polyol itself is not usually the final product, and its main use is as a soft segment prepolymer for synthesizing polyurethane (PU). The polycarbonate polyol needs to undergo polycondensation reaction with an isocyanate with a functionality of usually 2 or more, and therefore the chain transfer agent with a functionality of not less than 2 is used, so that the obtained polymer has hydroxyl groups at both ends, facilitating subsequent application.

[0024] Optionally, the epoxy compound is selected from one or more of epoxycyclohexane, epoxypropane or epoxyl chloroethane.

[0025] In summary, the present application includes at least one of the following beneficial effects: 1. The present application synthesizes a carborane derivative catalyst by reacting an alkyne with decaborane, which is used to replace the traditional catalyst. In the scheme of the present application, the carborane derivative catalyst cooperates with a chain initiator to form a high-efficiency catalytic system, which significantly accelerates the polymerization rate, greatly improves the reaction efficiency, reduces the production cost, and can obtain the target product in a shorter time. The carborane derivative catalyst has the characteristics of good stability, high safety and low cost, and has a wide application prospect in industry. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the structural formula of the catalyst obtained in Preparation Examples 1-4 of the present application. DETAILED DESCRIPTION

[0027] The present application will be further described in detail below in combination with the drawings.

[0028] Preparation Example 1 Under a nitrogen atmosphere, acetylene, decaborane, ethyl sulfide and toluene were added to a reaction bottle and heated and stirred to dissolve, wherein the molar ratio of acetylene, decaborane, ethyl sulfide and toluene was 1:1.5:9:100; acetylene was allowed to react with decaborane at 120℃, and after 16h of reaction, the temperature was lowered to room temperature, toluene was removed by reduced pressure distillation, to obtain a carborane derivative catalyst crude product, which was then recrystallized using acetone and petroleum ether, and finally the obtained product was dried in a vacuum drying box at 40℃ for 24h to obtain a carborane derivative catalyst, which is denoted as A1, and the structural formula of A1 is shown in FIG. 1. Figure 1

[0029] Preparation Example 2 ​Under the nitrogen atmosphere, p-phenylacetylene, decaborane, ethyl sulfide and toluene were added into the reaction bottle, heated and stirred to dissolve, wherein the molar ratio of acetylene, decaborane, ethyl sulfide and toluene was 1:1.5:9:100; the acetylene reacted with decaborane at 80℃, after 8h of reaction, the temperature was lowered to room temperature, toluene was removed by distillation under reduced pressure, to obtain the crude product of the carborane derivative catalyst, then recrystallized using acetone and petroleum ether, finally the obtained product was dried in a vacuum drying oven at 40℃ for 24h, to obtain the carborane derivative catalyst, recorded as A2, the structural formula of A2 is shown in the attached Figure 1 figure.

[0030] Preparation Example 3 Under the nitrogen atmosphere, p-phenylacetylene, decaborane, ethyl sulfide and toluene were added into the reaction bottle, heated and stirred to dissolve, wherein the molar ratio of acetylene, decaborane, ethyl sulfide and toluene was 1:1.5:9:100; the acetylene reacted with decaborane at 80℃, after 8h of reaction, the temperature was lowered to room temperature, toluene was removed by distillation under reduced pressure, to obtain the crude product of the carborane derivative catalyst, then recrystallized using acetone and petroleum ether, finally the obtained product was dried in a vacuum drying oven at 40℃ for 24h, to obtain the carborane derivative catalyst, recorded as A2, the structural formula of A2 is shown in the attached Figure 1 figure.

[0031] Preparation Example 4 Under the nitrogen atmosphere, p-phenylacetylene, decaborane, ethyl sulfide and toluene were added into the reaction bottle, heated and stirred to dissolve, wherein the molar ratio of acetylene, decaborane, ethyl sulfide and toluene was 1:1.5:9:100; the acetylene reacted with decaborane at 80℃, after 8h of reaction, the temperature was lowered to room temperature, toluene was removed by distillation under reduced pressure, to obtain the crude product of the carborane derivative catalyst, then recrystallized using acetone and petroleum ether, finally the obtained product was dried in a vacuum drying oven at 40℃ for 24h, to obtain the carborane derivative catalyst, recorded as A2, the structural formula of A2 is shown in the attached Figure 1 figure.

[0032] Example 1 Into a high-pressure reactor, 200 mmol of an epoxide compound (selected from the group consisting of epoxycyclohexane), 0.1 mmol of the carborane derivative catalyst obtained in Preparation Example 1, 0.1 mmol of a chain transfer agent (selected from the group consisting of 1,4-butanediol), and 0.2 mmol of a chain initiator (selected from the group consisting of triethylamine) were added. Carbon dioxide was introduced into the reactor to replace the air in the reactor for 10 minutes, and then the reactor was pressurized to a carbon dioxide reaction pressure of 2.0 MPa. The reaction temperature was set to 70°C, and the polymerization reaction was continued for 6 hours. After the polymerization reaction was completed, the reactor was cooled to room temperature, and a few drops of glacial acetic acid were added to the reaction system to terminate the reaction. The crude product obtained at room temperature was dissolved in dichloromethane, and then purified by repeatedly adding methanol for precipitation. Finally, the product was dried under vacuum at 40°C to obtain the polycarbonate polyol.

[0033] Example 2 Into a high-pressure reactor, 200 mmol of an epoxide compound (selected from the group consisting of epoxycyclohexane), 0.1 mmol of the carborane derivative catalyst obtained in Preparation Example 2, 0.1 mmol of a chain transfer agent (selected from the group consisting of 1,4-butanediol), and 0.2 mmol of a chain initiator (selected from the group consisting of triethylamine) were added. Carbon dioxide was introduced into the reactor to replace the air in the reactor for 10 minutes, and then the reactor was pressurized to a carbon dioxide reaction pressure of 2.0 MPa. The reaction temperature was set to 70°C, and the polymerization reaction was continued for 6 hours. After the polymerization reaction was completed, the reactor was cooled to room temperature, and a few drops of glacial acetic acid were added to the reaction system to terminate the reaction. The crude product obtained at room temperature was dissolved in dichloromethane, and then purified by repeatedly adding methanol for precipitation. Finally, the product was dried under vacuum at 40°C to obtain the polycarbonate polyol.

[0034] Example 3 Into a high-pressure reactor, 200 mmol of an epoxide compound (selected from the group consisting of epoxycyclohexane), 0.1 mmol of the carborane derivative catalyst obtained in Preparation Example 3, 0.1 mmol of a chain transfer agent (selected from the group consisting of 1,4-butanediol), and 0.2 mmol of a chain initiator (selected from the group consisting of triethylamine) were added. Carbon dioxide was introduced into the reactor to replace the air in the reactor for 10 minutes, and then the reactor was pressurized to a carbon dioxide reaction pressure of 2.0 MPa. The reaction temperature was set to 70°C, and the polymerization reaction was continued for 6 hours. After the polymerization reaction was completed, the reactor was cooled to room temperature, and a few drops of glacial acetic acid were added to the reaction system to terminate the reaction. The crude product obtained at room temperature was dissolved in dichloromethane, and then purified by repeatedly adding methanol for precipitation. Finally, the product was dried under vacuum at 40°C to obtain the polycarbonate polyol.

[0035] Example 4 Into a high-pressure reactor, 200 mmol of an epoxy compound (selected from epoxycyclohexane), 0.1 mmol of the carborane derivative catalyst obtained in Preparation Example 4, 0.1 mmol of a chain transfer agent (selected from 1,4-butanediol), and 0.2 mmol of a chain initiator (selected from triethylamine) were added. Carbon dioxide was introduced into the reactor to replace the air in the reactor for 10 min, and then the reactor was pressurized to a carbon dioxide reaction pressure of 2.0 MPa. The reaction temperature was set to 70°C, and the polymerization reaction was continued for 6 h. After the polymerization reaction was completed, the reactor was cooled to room temperature, and a few drops of glacial acetic acid were added to the reaction system to terminate the reaction. The crude product obtained at room temperature was dissolved in dichloromethane, and then purified by repeatedly adding methanol for precipitation. Finally, the product was dried under vacuum at 40°C to obtain the polycarbonate polyol.

[0036] Comparative Example 1 Into a high-pressure reactor, 200 mmol of an epoxy compound (selected from epoxycyclohexane), 0.1 mmol of triethylboron catalyst, 0.1 mmol of a chain transfer agent (selected from 1,4-butanediol), and 0.2 mmol of a chain initiator (selected from triethylamine) were added. Carbon dioxide was introduced into the reactor to replace the air in the reactor for 10 min, and then the reactor was pressurized to a carbon dioxide reaction pressure of 2.0 MPa. The reaction temperature was set to 70°C, and the polymerization reaction was continued for 6 h. After the polymerization reaction was completed, the reactor was cooled to room temperature, and a few drops of glacial acetic acid were added to the reaction system to terminate the reaction. The crude product obtained at room temperature was dissolved in dichloromethane, and then purified by repeatedly adding methanol for precipitation. Finally, the product was dried under vacuum at 40°C to obtain the polycarbonate polyol.

[0037] Performance Test The polycarbonate polyol products obtained in Examples 1-4 and Comparative Example 1 were measured for molecular weight and hydroxyl value by the hydroxyl value titration method, and the test results are shown in the following table.

[0038] Table 1 Test results of Examples 1-4 and Comparative Example 1 Number average molecular weight PDI Hydroxyl value Functionality Example 1 2077 1.2 167 2 Example 2 2365 1.1 223 2 Example 3 2776 1.1 284 2 Example 4 2450 1.1 244 2 Comparative Example 1 2218 1.3 185 2 According to the results of Examples 1-4 and Comparative Example 1, it is shown that, under the condition that other polymerization conditions remain the same, the carborane derivative catalyst synthesized according to the present application, in combination with a chain initiator, can significantly increase the molecular weight of the polycarbonate polyol product in a shorter reaction time, and the molecular weight distribution is narrower, the hydroxyl value is close, and even higher.

[0039] Therefore, the carbon borane derivative catalyst prepared in the present application can replace the catalysts currently used in the reaction of carbon dioxide and an epoxide compound in terms of reaction efficiency and catalytic activity, and the preparation steps of the carbon borane derivative catalyst in the present application are simple and easy to control, and the obtained carbon borane derivative catalyst is more stable and has high safety, thereby having great application prospect in the preparation of polycarbonate polyols.

[0040] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application, so: any equivalent changes made on the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for preparing a carbon dioxide-based polycarbonate polyol, characterized in that: Includes the following steps: An epoxy compound, a carborane derivative catalyst, a chain initiator, and a chain transfer agent are added to a reactor. Carbon dioxide is introduced to replace the air in the reactor. Then, the polymerization reaction is carried out under pressure, heating, and stirring. After the reaction is completed, acid is added to terminate the reaction. Then, the product is purified and dried to obtain the polycarbonate polyol. The carborane derivative catalyst is prepared by the following method: under a nitrogen atmosphere, alkynes with different substitutions, decborane, ethyl sulfide and toluene are added to a reaction flask in proportion. The reaction flask is sealed and heated and stirred to allow decborane to react with alkynes with different substitutions. After the reaction is completed, toluene is removed by vacuum distillation, and then recrystallized, filtered and dried to obtain the carborane derivative catalyst.

2. The method for preparing a carbon dioxide-based polycarbonate polyol according to claim 1, characterized in that: In the preparation method of the carborane derivative catalyst, the molar ratio of different substituted alkynes, decborane, ethyl sulfide and toluene is (1-1.2):(1.5-1.8):(9-9.3):(100-102).

3. The method for preparing a carbon dioxide-based polycarbonate polyol according to claim 2, characterized in that: In the preparation method of the carborane derivative catalyst, the reaction temperature is 80-140℃.

4. The method for preparing a carbon dioxide-based polycarbonate polyol according to claim 3, characterized in that: The different substituted alkynes are selected from one of acetylene, diphenylacetylene, p-methoxydiphenylacetylene, and di-tert-butylacetylene.

5. The method for preparing a carbon dioxide-based polycarbonate polyol according to claim 1, characterized in that: In the preparation step of the polycarbonate polyol, the chain initiator is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium fluoride, potassium fluoride, cesium carbonate, cesium fluoride, triethylamine, pyridine, triethylenediamine, 4-dimethylaminopyridine, N,N-diisopropylethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, bis(triphenylphosphine)ammonium chloride, potassium tert-butoxide, sodium tert-butoxide, and sodium ethoxide.

6. The method for preparing a carbon dioxide-based polycarbonate polyol according to claim 5, characterized in that: The molar ratio of the carborane derivative catalyst to the chain initiator is 1:0.5 to 1:

10.

7. The method for preparing a carbon dioxide-based polycarbonate polyol according to claim 5, characterized in that: The molar ratio of the epoxy compound to the carborane derivative catalyst is 1000:1 to 4000:

1.

8. The method for preparing a carbon dioxide-based polycarbonate polyol according to claim 5, characterized in that: The molar ratio of the epoxy compound to the chain transfer agent is 2000:1 to 2000:

20.

9. The method for preparing a carbon dioxide-based polycarbonate polyol according to claim 5, characterized in that: The chain transfer agent is a polyol or polycarboxylic acid with a functionality of not less than 2.

10. The method for preparing a carbon dioxide-based polycarbonate polyol according to claim 1, characterized in that: The epoxy compound is selected from one or more of cyclohexane oxide, propylene oxide, or chloroethylene oxide.

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