A process for the preparation of a hydroxy-terminated oxirane-tetrahydrofuran copolyether

Abstract

The application provides a preparation method of a terminal hydroxyl group-containing oxirane-tetrahydrofuran copolyether, which comprises the following steps: adding a catalyst into a first material system containing a solvent and a polyhydric alcohol under 20-35 DEG C, stirring for 0.5-1 h to obtain a second material system, adding tetrahydrofuran and oxirane into the second material system under-20-10 DEG C, stirring for a second time, adding the material to complete the third material system, stirring the third material system for a third time for 4-15 h to obtain the terminal hydroxyl group-containing oxirane-tetrahydrofuran copolyether; wherein the catalyst is a mixture of tin tetrachloride and trifluoroacetic acid, the catalyst is a mixture of tin tetrachloride and trifluoroacetic acid, and the mass ratio of tin tetrachloride to trifluoroacetic acid is 0.8-1.2:1. The preparation method is simple and easy to operate, and can prepare the terminal hydroxyl group-containing oxirane-tetrahydrofuran copolyether with a narrow molecular weight distribution, a high yield and a high average functionality.

Description

Technical Field

[0001] This invention relates to the field of fine chemical synthesis, specifically to a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether. Background Technology

[0002] In the reported synthetic methods for ethylene oxide (EO)-tetrahydrofuran (THF) coethers, boron trifluoride complexes are generally used as catalysts and polyols as initiators to cationicly polymerize ethylene oxide and tetrahydrofuran. The crude product is then subjected to multiple alkaline washes and deionized water washes to remove the catalyst and small impurity molecules, thus obtaining the finished ethylene oxide-tetrahydrofuran coether. However, this process has the following problems: First, the preparation of ethylene oxide-tetrahydrofuran coethers using boron trifluoride complexes as catalysts generally involves a long preparation cycle (typically about 24 hours), and the coether's functional grouping is limited. The low energy content is due to several factors. First, the "backbiting" of active centers on the molecular chain in the early stages of the reaction and the "tailbiting" in the later stages result in polyether end groups that are not entirely hydroxyl. This not only reduces the functionality of the copolyether but also negatively impacts the mechanical properties of subsequent polyurethane (PU) products. Second, the washing process of the crude product generates a large amount of acidic fluoride-containing wastewater, drastically increasing environmental costs and pressure, making it difficult for this technology to achieve green production goals. Third, during the copolymerization of ethylene oxide and tetrahydrofuran, 7-15%, or even as much as 18%, of cyclic oligomers are typically generated, reducing the yield of the target product. Therefore, finding suitable process conditions to reduce the generation of acidic fluoride-containing wastewater while ensuring high product functionality and yield is a key technical challenge that must be addressed in this field. Summary of the Invention

[0003] This invention provides a method for preparing hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether. This method is simple and easy to implement, and can produce hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether with a narrow molecular weight distribution, high yield and high average functionality. Furthermore, the catalyst can be removed by filtration in the later stage, reducing the generation of wastewater.

[0004] This invention provides a method for preparing hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, comprising the following steps:

[0005] At 20–35°C, a catalyst is added to a first material system containing a solvent and a polyol, and the mixture is stirred once for 0.5–1 h to obtain a second material system. At -20–10°C, tetrahydrofuran and ethylene oxide are added to the second material system, and the mixture is stirred a second time. After the addition is completed, a third material system is obtained. The third material system is stirred three times for 4–15 h to obtain the terminal hydroxyl ethylene oxide-tetrahydrofuran copolyether.

[0006] The catalyst is a mixture of tin tetrachloride and trifluoroacetic acid, with a mass ratio of tin tetrachloride to trifluoroacetic acid of 0.8 to 1.2:1.

[0007] The total amount of tetrahydrofuran and ethylene oxide used is in a mass ratio of 50 to 250:1 to the polyol.

[0008] Preferably, a mixture of tetrahydrofuran and ethylene oxide is added to the second material system, and the feeding is completed within 1 to 8 hours.

[0009] Preferably, the polyol is one or more of ethylene glycol, propylene glycol, butanediol, glycerol, trimethylolpropane, and trimethylolethane.

[0010] Preferably, the mass ratio of the catalyst to the polyol is 1 to 4:1.

[0011] Preferably, the solvent is one or more of toluene, benzene, dichloromethane, and dichloroethane.

[0012] Preferably, the stirring rate of the secondary stirring is 100-150 rpm, and the stirring rate of the tertiary stirring is 150-400 rpm.

[0013] Preferably, the solvent accounts for 15-40 wt% of the third material system.

[0014] Preferably, the three stirring operations are performed at -5 to 5°C.

[0015] Preferably, the three stirring times are 6 to 10 hours.

[0016] The preparation method provided by this invention can prepare hydroxyl-terminated ethylene oxide-tetrahydrofuran copolymer ethers with narrow molecular weight distribution, high functionality, and high yield. Furthermore, the catalyst used in this method can be removed without extensive water washing, thus avoiding the generation of large amounts of acidic fluoride-containing wastewater during the post-treatment process. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides a method for preparing hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, comprising the following steps:

[0019] At 20–35°C, a catalyst is added to a first material system containing a solvent and a polyol, and the mixture is stirred once for 0.5–1 h to obtain a second material system. At -20–10°C, tetrahydrofuran and ethylene oxide are added to the second material system, and the mixture is stirred a second time. After the addition is completed, a third material system is obtained. The third material system is stirred three times for 4–15 h to obtain the terminal hydroxyl ethylene oxide-tetrahydrofuran copolyether.

[0020] The catalyst is a mixture of tin tetrachloride and trifluoroacetic acid, with a mass ratio of tin tetrachloride to trifluoroacetic acid of 0.8 to 1.2:1.

[0021] The preparation method provided by this invention uses anhydrous tin tetrachloride and trifluoroacetic acid as co-catalysts and polyols as initiators to carry out cationic ring-opening polymerization of ethylene oxide and tetrahydrofuran, which can greatly shorten the preparation cycle, thereby reducing the probability of "backbiting" and ensuring high functionality of the product.

[0022] In this invention, the mass ratio of tin tetrachloride to trifluoroacetic acid is specified. Under this mass ratio, the reaction can be more easily controlled, and the molecular weight dispersion of the resulting hydroxyl-terminated ethylene oxide-tetrahydrofuran coether is more uniform. If the amount of tin tetrachloride is too large, explosive polymerization will occur, causing the reaction to fail.

[0023] It is understandable that the temperature was kept between -20 and 10°C throughout the above feeding and three stirring processes, and that secondary stirring was carried out throughout the feeding process.

[0024] In a preferred embodiment, the total amount of tetrahydrofuran and ethylene oxide, and the mass ratio of the polyol initiator, are 50 to 250:1. The mass ratio of monomer to initiator affects the reaction rate; within the range defined by this invention, the reaction rate can be made more suitable, avoiding being too slow or too fast, thereby obtaining a copolyether product with a narrow molecular weight distribution.

[0025] In a preferred embodiment, the ethylene oxide is pre-cooled at -30°C, then mixed with tetrahydrofuran to form a mixture, which is then added dropwise to the second material system.

[0026] In a preferred embodiment, a mixture of tetrahydrofuran and ethylene oxide is added to the second material system, and the addition is completed within 1-8 hours. The addition time of the monomer can control the monomer dropping rate, thereby regulating the polymerization effect of the hydroxyl-terminated ethylene oxide-tetrahydrofuran coether. This invention has found that the above-mentioned addition time is suitable for material systems of ton size or less, and within this time range, the polymerization effect of the hydroxyl-terminated ethylene oxide-tetrahydrofuran coether is better, which is beneficial for further improving the mechanical properties of subsequent polyurethane (PU) products. Simultaneously, the above-mentioned addition time can result in a narrower molecular weight distribution of the coether product. This is because: if the monomer addition rate is too fast, the exothermic reaction is rapid and extensive, making the reaction process difficult to control and potentially leading to explosive polymerization; while if the monomer addition rate is too slow, chain initiation occurs continuously during the continuous addition process. This manifests as some polymer chains being already very long while others are just beginning to initiate, ultimately resulting in inconsistent polymer chain lengths, i.e., a lower molecular weight and wider distribution of the coether product.

[0027] In a preferred embodiment, the polyol is one or more of ethylene glycol, propylene glycol, butanediol, glycerol, trimethylolpropane, and trimethylolethane.

[0028] In a preferred embodiment, the mass ratio of the catalyst to the polyol is 1 to 4:1.

[0029] In a preferred embodiment, the stirring rate of the secondary stirring is 100-150 rpm, and the stirring rate of the tertiary stirring is 150-400 rpm. This invention, by controlling the two stirring processes, can further control the polymerization rate and effect of the monomers. For example, the stirring rate of the primary stirring during the feeding process should not be too fast, otherwise it will cause raw material loss and / or the polymerization reaction to proceed too quickly and prematurely. The stirring rate of the primary stirring should also not be too slow, otherwise uneven mixing of the raw materials will lead to reaction, affecting the molecular weight distribution of the copolyether product. Conversely, if the stirring rate of the secondary stirring is too fast, explosive polymerization may occur; if it is too slow, the molecular weight of the copolyether product will decrease and its distribution will become wider.

[0030] The present invention does not particularly limit the stirring rate for one stirring cycle; for example, it can be 100-800 rpm, 200-600 rpm, 300-500 rpm, etc.

[0031] In a preferred embodiment, the solvent is one or more of toluene, benzene, dichloromethane, and dichloroethane.

[0032] Generally speaking, low solvent polarity can affect the molecular weight distribution of the product. In order to obtain a product with a narrower molecular weight distribution, toluene, which has lower polarity and lower toxicity, is preferred as the solvent.

[0033] In a preferred embodiment, the solvent accounts for 15-40 wt% of the third material system. This proportion of solvent can reduce the concentration of the mixed monomers of ethylene oxide and tetrahydrofuran in the reaction system, thereby reducing the reaction rate to a more suitable range.

[0034] In a preferred embodiment, the stirring is performed three times at a temperature of -5 to 5°C. This application has found that a temperature of -5 to 5°C can further improve product performance compared to -20 to 10°C.

[0035] In a preferred embodiment, the three stirring times are 6–10 hours. This application has found that stirring for this duration can further increase the molecular weight and average functionality of the product.

[0036] The present invention will be further described below with reference to specific embodiments:

[0037] Example 1

[0038] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0039] At 25℃, 240g of toluene and 2.40g of ethylene glycol were mixed and added to a reaction flask. Then, 3.36g of anhydrous tin tetrachloride and 4.00g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 30 min. At -5℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added dropwise (at a dropping rate of 300g / h). After the addition was complete, the mixture was stirred at 300 rpm and kept at -5℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution. The mixture was filtered and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P1.

[0040] Example 2

[0041] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0042] At 25℃, 240g of toluene and 2.40g of ethylene glycol were mixed and added to a reaction flask. Then, 3.36g of anhydrous tin tetrachloride and 3.12g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 30 min. At -5℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added dropwise (at a dropping rate of 300g / h). After the addition was complete, the mixture was stirred at 300 rpm and kept at -5℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution. The mixture was filtered and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P2.

[0043] Example 3

[0044] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0045] At 25℃, 400g of toluene and 2.40g of ethylene glycol were mixed and added to a reaction flask. Then, 3.36g of anhydrous tin tetrachloride and 3.12g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 30 min. At -5℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added dropwise (dropping rate 300g / h). After the addition was complete, the mixture was stirred at 300 rpm and kept at -5℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution, filtered, and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P3.

[0046] Example 4

[0047] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0048] At 25℃, 240g of toluene and 2.40g of ethylene glycol were mixed and added to a reaction flask. Then, 3.36g of anhydrous tin tetrachloride and 3.12g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 30 min. At -20℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added (at a rate of 300g / h). After the addition was complete, the mixture was stirred at 300 rpm and kept at -20℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution. The mixture was filtered and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P4.

[0049] Example 5

[0050] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0051] At 25℃, 240g of toluene and 2.40g of ethylene glycol were mixed and added to a reaction flask. Then, 3.36g of anhydrous tin tetrachloride and 3.12g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 30 min. At 10℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added dropwise (dropping rate 300g / h). After the addition was complete, the mixture was stirred at 300 rpm and kept at 10℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution. After filtration, the mixture was extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P5.

[0052] Example 6

[0053] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0054] At 25℃, 240g of toluene and 2.40g of ethylene glycol were mixed and added to a reaction flask. Then, 2g of anhydrous tin tetrachloride and 1.9g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 30 min. At -5℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added dropwise (dropping rate 300g / h). After the addition was complete, the mixture was stirred at 300 rpm and kept at -5℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution. The mixture was filtered and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P6.

[0055] Example 7

[0056] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0057] At 25℃, 240g of toluene and 2.40g of ethylene glycol were mixed and added to a reaction flask. Then, 2g of anhydrous tin tetrachloride and 1.9g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 30 min. At -5℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added dropwise (at a dropping rate of 100g / h). After the addition was complete, the mixture was stirred at 300 rpm and kept at -5℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution. The mixture was filtered and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P7.

[0058] Example 8

[0059] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0060] At 25℃, 240g of toluene and 1.90g of propylene glycol were mixed and added to a reaction flask. Then, 2g of anhydrous tin tetrachloride and 1.9g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 40 min. At -5℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added dropwise (at a dropping rate of 300g / h). After the addition was complete, the mixture was stirred at 300 rpm and kept at -5℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution. The mixture was filtered and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P8.

[0061] Example 9

[0062] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0063] At 25℃, 240g of toluene and 2g of ethylene glycol were mixed and added to a reaction flask. Then, 2g of anhydrous tin tetrachloride and 1.9g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 30 min. At -5℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added dropwise (at a dropping rate of 300g / h). After the addition was complete, the mixture was stirred at 200 rpm and kept at -5℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution. The mixture was filtered and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P9.

[0064] Example 10

[0065] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0066] At 25℃, 240g of toluene and 3.0g of glycerol were mixed and added to a reaction flask. Then, 2g of anhydrous tin tetrachloride and 1.9g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 30 min. At -5℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added dropwise (at a dropping rate of 300g / h). After the addition was complete, the mixture was stirred at 300 rpm and kept at -5℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution. The mixture was filtered and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P10.

[0067] Example 11

[0068] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0069] At 25℃, 240g of toluene and 2.4g of ethylene glycol were mixed and added to a reaction flask. Then, 2g of anhydrous tin tetrachloride and 1.9g of trifluoroacetic acid were added. Under N2 protection, the mixture was stirred at 120 rpm for 30 min. At 5℃, a mixed solution of 372g of tetrahydrofuran and 228g of ethylene oxide was added dropwise (at a dropping rate of 300g / h). After the addition was complete, the mixture was stirred at 300 rpm and kept at 5℃ for 10 h. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution. The mixture was filtered and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain sample P11.

[0070] Comparative Example 1

[0071] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0072] 240g toluene, 2.40g initiator, 3.36g anhydrous tin tetrachloride, and 3.12g trifluoroacetic acid were added to a reaction flask. Under N2 protection, the temperature was maintained at 15℃, and the mixture was stirred at a stirring rate of 120 rpm. A mixed solution of 372g tetrahydrofuran and 228g ethylene oxide was added dropwise (dropping rate 300g / h). After the addition was completed, the mixture was stirred at a stirring rate of 300 rpm and kept at 15℃ for 10 hours. After the reaction was completed, the mixture was washed with a 10wt% methanol aqueous solution in an equal volume ratio to the reaction solution, filtered, and then extracted three times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain the sample.

[0073] Comparative Example 2

[0074] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0075] 240g toluene, 2.4g ethylene glycol (initiator), and 4.9g boron trifluoride diethyl ether complex were added to a reaction flask. Under N2 protection, the temperature was maintained at -5℃, and the mixture was stirred at a stirring rate of 120 rpm. 372g tetrahydrofuran and 228g ethylene oxide mixed solution were then added dropwise (dropping rate 300g / h). After the addition was complete, the mixture was stirred at a stirring rate of 300 rpm and kept at -5℃ for 24 hours. After the reaction was completed, a 1% sodium hydroxide aqueous solution with an equal volume ratio to the reaction solution was added to quench the reaction. The mixture was then washed 3-5 times with deionized water until neutral, and then extracted 3 times with an equal volume ratio of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, the residual solvent was removed by vacuum distillation to obtain the sample.

[0076] Comparative Example 3

[0077] This example describes a method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, which includes the following steps:

[0078] 240g toluene, 2.4g ethylene glycol (initiator), 3.0g anhydrous tin tetrachloride, and 3.5g trifluoromethanesulfonic acid were added to a reaction flask. Under N2 protection, the temperature was maintained at -5℃, and the mixture was stirred at a stirring rate of 120 rpm. Then, a mixed solution of 372g tetrahydrofuran and 228g ethylene oxide was added dropwise (at a dropping rate of 300g / h). After the addition was complete, the mixture was stirred at a stirring rate of 300 rpm and kept at -5℃ for 10 hours. After the reaction was completed, the mixture was washed with a 10wt% methanol-water solution (equal in volume to the reaction solution), filtered, and then extracted three times with an equal volume of petroleum ether extract to remove small molecule byproducts and organic solvents. Finally, residual solvent was removed by vacuum distillation to obtain the sample.

[0079] Performance testing

[0080] Test content and methods:

[0081] The average functionality is calculated according to the following formula 1:

[0082] Where Mn is the molecular weight;

[0083] Molecular weight (Mn) and molecular weight distribution were determined by gel permeation chromatography (GPC), and the test method was in accordance with GJB 5395-2005.

[0084] The hydroxyl value test method refers to GJB 5395-2005; the viscosity is tested by a rotational viscometer, and the method refers to GJB5395-2005.

[0085] Product yield calculation formula: Yield = Product mass / (Amount of mixed monomers of tetrahydrofuran and ethylene oxide + Amount of initiator) · 100%;

[0086] The test results are shown in Table 1:

[0087] Table 1:

[0088]

[0089] As shown in Table 1, compared with the comparative examples, the hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyethers obtained in Examples 1-11 can simultaneously ensure higher molecular weight uniformity, higher hydroxyl value, moderate viscosity, and higher yield.

[0090] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a hydroxyl-terminated ethylene oxide-tetrahydrofuran copolyether, characterized in that, Includes the following steps: At 20~35℃, a catalyst is added to a first material system containing solvent and polyol, and the mixture is stirred once for 0.5~1h to obtain a second material system. At -20~10℃, tetrahydrofuran and ethylene oxide are added to the second material system, and the mixture is stirred a second time. After the addition is completed, a third material system is obtained. The third material system is stirred three times for 4~15h to obtain the terminal hydroxyl ethylene oxide-tetrahydrofuran copolyether. The catalyst is a mixture of tin tetrachloride and trifluoroacetic acid, with a mass ratio of tin tetrachloride to trifluoroacetic acid of 0.8 to 1.2:

1. A mixture of tetrahydrofuran and ethylene oxide is added to the second material system, and the addition is completed within 1 to 8 hours. The temperature is maintained at -20 to 10°C throughout the addition and three stirring processes, and secondary stirring is performed continuously during the addition process.

2. The preparation method according to claim 1, characterized in that, The total amount of tetrahydrofuran and ethylene oxide and the mass ratio of the polyol are 50~250:

1.

3. The preparation method according to claim 1, characterized in that, The polyol is one or more of ethylene glycol, propylene glycol, butanediol, glycerol, trimethylolpropane, and trimethylolethane.

4. The preparation method according to claim 3, characterized in that, The mass ratio of the catalyst to the polyol is 1 to 4:

1.

5. The preparation method according to claim 1, characterized in that, The solvent is one or more of toluene, benzene, dichloromethane, and dichloroethane.

6. The preparation method according to claim 1, characterized in that, The stirring rate for the secondary stirring is 100-150 rpm, and the stirring rate for the tertiary stirring is 150-400 rpm.

7. The preparation method according to claim 1, characterized in that, The solvent accounts for 15-40 wt% of the third material system.

8. The preparation method according to claim 1, characterized in that, The three stirring operations were carried out at -5 to 5°C.

9. The preparation method according to claim 1, characterized in that, The three stirring times are 6-10 hours.

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