Preparation method and application of polyether glycol

Abstract

The invention relates to a preparation method and application of polyether glycol, the structural formula of the polyether glycol is shown in the specification, the preparation method comprises the following steps: trimethylolpropane and carbonic ester are subjected to transesterification to obtain a ketal compound, then the ketal compound is used as an initiator to polymerize ethylene oxide to obtain nonionic polyether mono-alcohol, and the nonionic polyether mono-alcohol is used as a solvent. And carrying out Williamson reaction on the polyether monoalcohol to obtain methyl-terminated polyether, and carrying out ring-opening reaction on the methyl-terminated polyether under an acidic condition to obtain the nonionic polyether glycol. The preparation process is wide in raw material source, low in cost, mild in condition, efficient in reaction and wide in industrialization prospect.

Description

Technical Field

[0001] This invention relates to the field of polyols, and more specifically to a method for preparing a nonionic polyether diol. Background Technology

[0002] Emulsifiers are substances that improve the surface tension between various constituent phases in an emulsion, forming a uniform dispersion or emulsion. Under certain conditions, they enable two complementary miscible liquids to form a stable solution dispersion system. Emulsifiers are widely used in waterborne polyurethane systems and play a very important role. Common emulsifiers include anionic, cationic, and nonionic emulsifiers. Anionic emulsifiers include sulfonates (alkyl sulfonates, alkylbenzene sulfonates, etc.), sulfates (fatty alcohol sulfates, fatty alcohol ether sulfates, etc.), carboxylates, phosphates, etc.; nonionic surfactants include polyoxyethylene ethers (fatty alcohol polyoxyethylene ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, etc.). Conventional emulsifiers aggregate on the surface of adhesive particles through physical adsorption and are easily retained in the product, affecting the performance of subsequent products such as adhesives and coatings.

[0003] Nonionic reactive surfactants are a novel class of surfactants with reactive functional groups in their structure, enabling them to participate in reactions and directly attach to the polymer chain, becoming part of the polymer. They can exert emulsifying properties while preventing the migration of free emulsifiers in the product, thus improving emulsion stability and film performance. Furthermore, nonionic reactive surfactants do not exist in an ionic state in solution, exhibiting strong stability and being less affected by electrolytes, acids, and alkalis. They are also compatible with other types of surfactants. Currently, there are relatively few reactive emulsifiers used in waterborne polyurethane systems; the only mature product on the market is Pastor's Yerm 120.

[0004] Patent CN114672029A discloses a nonionic organosilicon surfactant. The aqueous organosilicon resin prepared from it has good compatibility with silicone oil and can reduce the surface tension between the water and oil phases. However, it does not participate in the reaction and exists only as an additive, remaining free in the polymer crosslinking network. This makes it prone to migration and aggregation on the film surface, resulting in a significant decrease in mechanical properties. Patents CN111019119A and CN109796587A disclose reactive emulsifiers, which anchor emulsifier molecules to the particle surface through copolymerization with monomers, making them less prone to migration and aggregation. However, in order to place the unsaturated double bonds at the hydrophobic end of the emulsifier molecules, the synthesis methods of both require the use of alkaline catalysts and high reaction temperatures, leading to an unavoidable loss of double bond content and a reduction in product performance.

[0005] Currently, the mature processes for preparing these compounds, as reported in public records, mainly rely on ketal reactions. However, these reactions suffer from low yields and environmental pollution. With increasing market demands for product stability and weather resistance, and a growing demand for these products, there is an urgent need to develop nonionic emulsifiers with superior performance and suitability for industrial applications. Polyether polyols, as an important class of compounds, possess significant development potential. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing polyether diols, the entire process route of which has the characteristics of mild reaction conditions, environmental friendliness and high yield.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A method for preparing a polyether diol includes the following steps:

[0009] (1) Trimethylolpropane and carbonate compounds Ester exchange reaction under the action of a catalyst yields ketal compounds. R1 and R2 are selected from H or C1-C6 alkyl groups, respectively;

[0010] (2) Using ketal compounds as raw materials, the active intermediate is obtained by heating and decomposition in the presence of a catalyst.

[0011] (3) Polymerization of ethylene oxide with an active intermediate as an initiator in the presence of a catalyst yields polyether monools. Where n = 5 to 100;

[0012] (4) Polyether monools are subjected to a Williamson reaction with an alkali and dimethyl sulfate or dimethyl carbonate or a halogenated hydrocarbon to obtain methyl-terminated polyethers.

[0013] (5) Methyl-terminated polyethers undergo a ring-opening reaction in the presence of a catalyst to obtain polyether diols.

[0014] As a preferred embodiment, the reaction temperature in step (1) is 60–80°C, and the reaction time is 4–20 hours under a vacuum degree greater than 0.06 MPa.

[0015] As a preferred embodiment, in step (1), the molar ratio of trimethylolpropane to carbonate compounds is 1 to 6:1.

[0016] As a preferred embodiment, in step (1), the catalyst is one or more of organic amines, solid acid catalysts, and strongly acidic cation exchange resins, preferably one or more of triethylamine, solid phosphoric acid, and strongly acidic cation exchange resins.

[0017] As a preferred embodiment, in step (1), the amount of catalyst used is 0.3% to 3% of the mass of trimethylolpropane.

[0018] As a preferred embodiment, in step (2), the reaction temperature is 100-150°C, and the reaction time is 2-10 hours under a vacuum of greater than 0.09 MPa.

[0019] As a preferred embodiment, in step (2), the catalyst is one or more of solid acid, organic amine, and metal chloride, preferably one or more of solid phosphoric acid, triethylamine, and magnesium chloride.

[0020] As a preferred embodiment, in step (2), the amount of catalyst used is 0.2% to 0.5% of the amount of ketal compound used.

[0021] As a preferred embodiment, in step (3), the active intermediate and the catalyst react at a vacuum of greater than 0.09 MPa and a temperature of 95–110 °C for 2–5 hours; then react with ethylene oxide at a reaction pressure between 0.01 MPa and 0.35 MPa.

[0022] As a preferred embodiment, in step (3), the polyether monool obtained after the reaction of ethylene oxide with the active intermediate has a molecular weight of 300 to 2000.

[0023] As a preferred embodiment, in step (3), the catalyst is one or more of alkali metal hydroxide, alkaline earth metal oxide, and alkaline earth metal hydroxide.

[0024] As a preferred embodiment, in step (3), the amount of catalyst used is 0.1% to 0.5% of the total mass of the active intermediate and ethylene oxide.

[0025] As a preferred embodiment, in step (4), the polyether monool is first reacted with an alkali at a temperature of 30-120°C, preferably 45-100°C, for 1-8 hours, and then dimethyl sulfate or dimethyl carbonate or haloalkane is added and reacted at a temperature of 30-100°C for 2-15 hours to obtain methyl-terminated polyether.

[0026] As a preferred embodiment, in step (4), the molar ratio of polyether monool to alkali to dimethyl sulfate or dimethyl carbonate or haloalkanes is 1:1.2 to 2:1.5 to 4.

[0027] As a preferred embodiment, in step (4), the alkali is one or more of an alkali metal element or an alkali metal hydroxide, preferably one or more of sodium methoxide, potassium methoxide, or potassium hydroxide.

[0028] As a preferred embodiment, in step (4), the haloalkane is one or more of chloromethane, bromomethane, and iodomethane.

[0029] As a preferred embodiment, in step (5), the methyl-terminated polyether reacts with the catalyst at a vacuum of greater than 0.09 MPa and a temperature of 100–200 °C for 2–10 hours.

[0030] As a preferred embodiment, in step (5), the catalyst is one or more of protic acid, Lewis acid, and carbocation, preferably one or more of sulfuric acid, boron trifluoride, and aluminum trichloride.

[0031] As a preferred embodiment, in step (5), the amount of catalyst used is 0.1% to 0.3% of the mass of methyl-terminated polyether.

[0032] The reaction process is shown in the following equation:

[0033]

[0034] The polyether diol of the present invention has an average molecular weight of 500 to 4500, preferably an average molecular weight of 800 to 2000.

[0035] The polyether diol prepared by this invention can be used as a surfactant in the preparation of aqueous polyurethane emulsions or toiletries.

[0036] Unless otherwise stated, the molecular weights in the examples are exponential average molecular weights, or evaluative molecular weights.

[0037] This invention develops a method for synthesizing nonionic reactive emulsifiers of polyether diols. This method overcomes the limitations of traditional processes, using transesterification as a key step, and achieves a significant improvement in raw material utilization and a simplified and optimized reaction process. The resulting polyether diol, as an emulsifier, has superior stability compared to traditional emulsifiers and is suitable for various applications such as waterborne resin synthesis, polyurethane dispersion preparation, and surfactants. Detailed Implementation

[0038] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0039] Example 1

[0040] (1) Preparation of ketal compounds

[0041] 268 g of trimethylolpropane, 236 g of diethyl carbonate, and 1.512 g of strongly acidic cation exchange resin were added to a three-necked flask. The mixture was heated to 60 °C and reacted for 4 hours to obtain a yellow reaction solution. After the reaction was complete, 50% potassium hydroxide solution was added to the reaction solution to adjust the pH to 7. Diatomaceous earth adsorbent was added, and the mixture was dehydrated under vacuum at 130 °C. The dehydrated reaction solution was filtered, and the filtrate was collected to obtain 300 g of a light yellow transparent liquid, with a yield of 94%.

[0042] The gas chromatography conditions were as follows: Shimadzu 2010 gas chromatograph (FID detector), DB-5 column, 30 mm column length, 0.25 mm column diameter, 0.25 μm film thickness, holding at 50 °C for 2 minutes, increasing to 80 °C at 5 °C / min and holding for 5 minutes, increasing to 260 °C at 20 °C / min and holding for 15 minutes. The injection port temperature was 280 °C, the detection chamber temperature was 300 °C, the flame ionization detector was used, the solvent was ethanol, the injection volume was 0.2 μL, the retention time was 18.2 min, and the product purity was 99.6%.

[0043] The product structural formula is:

[0044] (2) Preparation of active intermediates

[0045] 0.348 g of triethylamine and 160 g of the prepared ketal compound were reacted at 100 °C under a vacuum of 0.09 MPa for 2 hours to obtain an active intermediate. Diatomaceous earth adsorbent was added, and the mixture was dehydrated under vacuum at 100 °C. The dehydrated reaction solution was filtered, and the filtrate was collected to obtain 110 g of a light yellow transparent liquid with a yield of 95%.

[0046] The product structural formula is:

[0047] (3) Preparation of polyether monools

[0048] Accurately weigh 1369g of ethylene oxide and place it in a storage tank. Place 232g of the prepared active intermediate and 1.6g of potassium hydroxide in a 2L reactor. Replace the air with nitrogen three times, then heat to 95℃ and dehydrate under vacuum for 1 hour (vacuum degree is 0.098MPa). Then start adding ethylene oxide, maintaining the reactor temperature at 95℃ and the pressure at 0.1~0.3MPa, and continuously add ethylene oxide at a rate of 2g / min. After the ethylene oxide feeding is completed, age the product at 95℃ for 2 hours. Remove the unreacted ethylene oxide under vacuum, cool it down and discharge to obtain 1584g of waxy substance, i.e., polyether monool, with a yield of 99%. The hydroxyl value was determined to be 70mg KOH / g by the phthalic anhydride-pyridine method (GB / T12008.3-2009), and the average molecular weight was 800.

[0049] The product structural formula is:

[0050] (4) Preparation of methyl-terminated polyethers

[0051] Accurately weigh 400g of the polyether monool obtained in the previous step and add it to a three-necked flask. Heat the flask to 45°C, and then add 32.4g of sodium methoxide to the reaction solution under nitrogen protection. Maintain the reaction temperature at 45°C for 1 hour. Then, slowly add 94.5g of dimethyl sulfate dropwise, completing the addition within 1 hour. Continue the reaction at 30°C for another 2 hours to obtain 394.8g of methyl-terminated polyether, with a yield of 97%.

[0052] The product structural formula is:

[0053] (5) Preparation of nonionic polyether diol

[0054] Accurately weigh 814g of the methyl-terminated polyether obtained in the previous step and add it to a three-necked flask. Add 0.814g of sulfuric acid and react at 100°C under a vacuum of 0.098MPa for 2 hours. Then, add KOH to adjust the pH to neutral. Next, add 2g of activated clay under nitrogen protection for decolorization and removal of metal ions. Stir for 1 hour, and then dehydrate and volatilize under vacuum for 2 hours. Filter the reaction product to obtain 815.36g of waxy polyether diol, with a yield of 98%.

[0055] The product structural formula is:

[0056] Example 2

[0057] (1) Preparation of ketal compounds

[0058] 804 g of trimethylolpropane, 236 g of diethyl carbonate, and 17.16 g of triethylamine were added to a three-necked flask, heated to 70 °C, and reacted for 12 h to obtain a yellow reaction solution. After the reaction was complete, 50% potassium hydroxide solution was added to the reaction solution to adjust the pH to 7, diatomaceous earth adsorbent was added, and the solution was dehydrated under vacuum at 130 °C. The dehydrated reaction solution was filtered, and the filtrate was collected to obtain 300 g of a light yellow transparent liquid, with a yield of 94%.

[0059] The product structural formula is:

[0060] (2) Preparation of active intermediates

[0061] 0.60g of solid phosphoric acid and 160g of the prepared ketal compound were reacted under a vacuum of 0.09MPa at 125°C for 6 hours to obtain an active intermediate. Diatomaceous earth adsorbent was added, and the mixture was dehydrated under vacuum at 130°C. The dehydrated reaction solution was filtered, and the filtrate was collected to obtain 110g of a light yellow transparent liquid with a yield of 95%.

[0062] The product structural formula is:

[0063] (3) Preparation of polyether monools

[0064] Accurately weigh 2570g of ethylene oxide and place it in a storage tank. Place 232g of the prepared active intermediate and 8.4g of sodium hydroxide in a 2L reactor. Replace the air with nitrogen three times, then heat to 103℃ and dehydrate under vacuum for 1 hour (vacuum degree is 0.098MPa). Then start adding ethylene oxide, maintaining the reactor temperature at 103℃ and the pressure at 0.1~0.3MPa, and continuously add ethylene oxide at a rate of 2g / min. After the ethylene oxide feeding is completed, age the reaction at 103℃ for 4 hours. Remove the unreacted ethylene oxide under vacuum, cool and discharge to obtain 2773g of waxy substance, i.e., polyether monool, with a yield of 99%. The hydroxyl value was determined to be 40mg KOH / g by the phthalic anhydride-pyridine method (GB / T 12008.3-2009), and the average molecular weight was 1400.

[0065] The product structural formula is:

[0066] (4) Preparation of methyl-terminated polyethers

[0067] Accurately weigh 700g of the polyether monool obtained in the previous step and add it to a three-necked flask. Heat the flask to 73°C, and then add 56g of potassium methoxide to the reaction solution under nitrogen protection. Keep the reaction at 73°C for 5 hours. Then slowly add 123.75g of dimethyl carbonate, which is added within 1 hour. Continue the reaction at 65°C for another 9 hours to obtain 685.79g of methyl-terminated polyether, with a yield of 97%.

[0068] The product structural formula is:

[0069] (5) Preparation of nonionic polyether diol

[0070] Accurately weigh 1414g of the methyl-terminated polyether obtained in the previous step and add it to a three-necked flask. Add 2.83g of boron trifluoride and react at 150℃ under a vacuum of 0.098MPa for 6 hours. Then add KOH to adjust the pH to neutral. Next, add 2g of activated clay under nitrogen protection for decolorization and removal of metal ions. Stir for 1 hour, and then dehydrate and volatilize under vacuum for 2 hours. Filter the reaction product to obtain 1403g of waxy polyether diol, with a yield of 98%.

[0071] The product structural formula is:

[0072] Example 3

[0073] (1) Preparation of ketal compounds

[0074] 1608 g of trimethylolpropane, 236 g of diethyl carbonate, and 55.32 g of solid phosphoric acid were added to a three-necked flask, heated to 80 °C, and reacted for 20 h to obtain a yellow reaction solution. After the reaction was completed, 50% potassium hydroxide solution was added to the reaction solution to adjust the pH to 7, diatomaceous earth adsorbent was added, and the solution was dehydrated under vacuum at 130 °C. The dehydrated reaction solution was filtered, and the filtrate was collected to obtain 300 g of a light yellow transparent liquid, with a yield of 94%.

[0075] The product structural formula is:

[0076] (2) Preparation of active intermediates

[0077] 0.87 g of magnesium chloride and 160 g of the prepared ketal compound were reacted at 150 °C under a vacuum of 0.09 MPa for 10 hours to obtain an active intermediate. Diatomaceous earth adsorbent was added, and the mixture was dehydrated under vacuum at 130 °C. The dehydrated reaction solution was filtered, and the filtrate was collected to obtain 110 g of a light yellow transparent liquid with a yield of 95%.

[0078] The product structural formula is:

[0079] (3) Preparation of polyether monools

[0080] Accurately weigh 3770g of ethylene oxide and place it in a storage tank. Place 232g of the prepared active intermediate and 20g of potassium oxide in a 2L reactor. Replace the air with nitrogen three times, then heat to 110℃ and dehydrate under vacuum for 1 hour (vacuum degree is 0.098MPa). Then start adding ethylene oxide, maintaining the reactor temperature at 110℃ and the pressure at 0.1~0.3MPa, and continuously add ethylene oxide at a rate of 2g / min. After the ethylene oxide feeding is completed, age the product at 110℃ for 5 hours. Remove the unreacted ethylene oxide under vacuum, cool it down and discharge it to obtain 3961g of waxy substance, i.e., polyether monool, with a yield of 99%. The hydroxyl value was determined to be 28mg KOH / g by the phthalic anhydride-pyridine method (GB / T 12008.3-2009), and the average molecular weight was 2000.

[0081] The product structural formula is:

[0082] (4) Preparation of methyl-terminated polyethers

[0083] Accurately weigh 1000g of the polyether monool obtained in the previous step and add it to a three-necked flask. Heat the flask to 100℃, and then add 56g of potassium hydroxide to the reaction solution under nitrogen protection. Keep the reaction at 100℃ for 8 hours. Start slowly introducing 100g of chloromethane, and complete the addition within 1 hour. Then continue the reaction at 100℃ for another 15 hours to obtain 976.8g of methyl-terminated polyether, with a yield of 97%.

[0084] The product structural formula is:

[0085] (5) Preparation of nonionic polyether diol

[0086] Accurately weigh 2014g of the methyl-terminated polyether obtained in the previous step and add it to a three-necked flask. Add 6.04g of aluminum trichloride and react at 200℃ under a vacuum of 0.098MPa for 10 hours. Then add KOH to adjust the pH to neutral. Next, add 2g of activated clay under nitrogen protection for decolorization and removal of metal ions. Stir for 1 hour, and then dehydrate and volatilize under vacuum for 2 hours. Filter the reaction product to obtain 1991g of polyether diol, with a yield of 98%.

[0087] The product structural formula is:

[0088] Application Example 1

[0089] Accurately weigh 56g of HDI (hexamethylene diisocyanate), 594g of C2020 (propylene glycol polyether polyol), 66g of the nonionic emulsifier prepared in Example 1, 0.036g of bismuth neodecanoate, and 71.6g of acetone, add them to a three-necked flask, heat to 80°C and stir for 4 hours, then degas using a vacuum pump at a vacuum degree of less than 0.005 MPa for 1 hour to obtain 756g of waterborne polyurethane resin.

[0090] Add 700g of waterborne polyurethane resin to a homogenizer, increase the rotation speed to 3000r, and slowly add deionized water drop by drop. The viscosity of the resin gradually increases and becomes a viscous paste. Continue to add deionized water. When the viscosity drops sharply, it means that the phase inversion is complete. Then add the remaining deionized water all at once. The total mass of the above deionized water is 210g. Increase the rotation speed to 5000r and continue homogenizing for 30min to obtain waterborne polyurethane emulsion. The sample is marked as 1#.

[0091] Comparative Example 1

[0092] Accurately weigh 56g of HDI (hexamethylene diisocyanate), 594g of C2020 (propylene glycol polyether polyol), 6.27g of sodium ethylenediamine ethanesulfonate, 0.036g of bismuth neodecanoate, and 71.6g of acetone, add them to a three-necked flask, heat to 80℃ and stir for 4h. Then degas using a vacuum pump at a vacuum degree of less than 0.005Mpa for 1h to obtain 756g of waterborne polyurethane resin.

[0093] Add 700g of waterborne polyurethane resin to a homogenizer, increase the rotation speed to 3000r, and slowly add deionized water drop by drop. The viscosity of the resin gradually increases and becomes a viscous paste. Continue to add deionized water. When the viscosity drops sharply, it means that the phase inversion is complete. Then add the remaining deionized water all at once. The total mass of the above deionized water is 210g. Increase the rotation speed to 5000r and continue homogenizing for 30min to obtain waterborne polyurethane emulsion. The sample is marked as 2#.

[0094] The performance of the aqueous polyurethane emulsions prepared in Example 1 and Comparative Example 1 was tested. The thermal stability test involved placing the aqueous polyurethane emulsion in a thumb-sized bottle and storing it in an oven at 50°C for 7 days, observing for any stratification. The centrifugal stability test involved placing the aqueous polyurethane emulsion in centrifuge tubes and centrifuging at 4000 rpm for 10 minutes, observing for any stratification. The performance test results showed that sample #1 did not exhibit stratification after both thermal and centrifugal stability tests, while sample #2 showed significant stratification after both tests. Compared with the emulsifier sodium ethylenediamine ethanesulfonate, this improved the stability of the aqueous polyurethane emulsion.

[0095] Finally, it should be noted that the above embodiments are only used to describe preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that various modifications and improvements made to the technical solutions of the present invention by means of modifications or equivalent substitutions should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a polyether diol, comprising the following steps: (1) Trimethylolpropane and carbonate compounds Ester exchange reaction under the action of a catalyst yields ketal compounds. R1 and R2 are selected from H or C1-C6 alkyl groups, respectively; (2) Using ketal compounds as raw materials, the active intermediate is obtained by heating and decomposition in the presence of a catalyst. (3) Polymerization of ethylene oxide with an active intermediate as an initiator in the presence of a catalyst yields polyether monools. Where n = 5 to 100; (4) Polyether monools are subjected to a Williamson reaction with an alkali and dimethyl sulfate or dimethyl carbonate or a halogenated hydrocarbon to obtain methyl-terminated polyethers. (5) Methyl-terminated polyethers undergo a ring-opening reaction in the presence of a catalyst to obtain polyether diols.

2. The method as described in claim 1, characterized in that, The reaction temperature in step (1) is 60-80°C; the molar ratio of trimethylolpropane to carbonate compounds is 1-6:

1.

3. The method according to claim 1 or 2, wherein in step (1), the catalyst is one or more of organic amines, solid acid catalysts, and strongly acidic cation exchange resins; and / or, the amount of catalyst used is 0.3% to 3% of the mass of trimethylolpropane.

4. The method according to any one of claims 1-3, characterized in that, In step (2), the reaction temperature is 100-150°C; and / or the catalyst is one or more of solid acid, organic amine, and metal chloride, preferably one or more of solid phosphoric acid, triethylamine, and magnesium chloride; the amount of catalyst used is 0.2%-0.5% of the amount of ketal compound used.

5. The method according to any one of claims 1-4, characterized in that, In step (3), the active intermediate and the catalyst react for 2 to 5 hours at a vacuum of greater than 0.09 MPa and a temperature of 95 to 110°C; then they react with ethylene oxide at a pressure between 0.01 MPa and 0.35 MPa.

6. The method according to any one of claims 1-5, characterized in that, In step (3), the polyether monool obtained after the reaction of ethylene oxide with the active intermediate has a molecular weight of 300 to 2000.

7. The method according to any one of claims 1-6, characterized in that, In step (3), the catalyst is one or more of alkali metal hydroxide, alkaline earth metal oxide, and alkaline earth metal hydroxide; and / or, the amount of catalyst used is 0.1% to 0.5% of the total mass of the active intermediate and ethylene oxide.

8. The method according to any one of claims 1-7, characterized in that, In step (4), the polyether monool is first reacted with an alkali at a temperature of 30-120°C, preferably 45-100°C, for 1-8 hours, and then dimethyl sulfate or dimethyl carbonate or haloalkanes are added and reacted at a temperature of 30-100°C for 2-15 hours to obtain methyl-terminated polyether.

9. The method according to any one of claims 1-8, characterized in that, The average molecular weight of the polyether diol is between 500 and 4500; preferably, the average molecular weight is between 800 and 2000.

10. Use of the polyether polyol prepared by the method of claims 1-9 for the preparation of surfactants in aqueous polyurethane emulsions or toiletries.

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