Method for refining methyl-terminated polyethers

Abstract

The application belongs to the technical field of polyether refining, and particularly relates to a methyl-terminated polyether refining treatment method. The method comprises the following steps: adding water to a methyl-terminated polyether sample to be refined and stirring, so that the salt is dissolved in water and then separated by layering; the polyether layer after separation is stirred with water again, and then separated by layering to obtain a preliminary sample; the methyl-terminated polyether sample to be refined is taken again, heated, stirred with water and acid to adjust pH, and a sample A is obtained; the preliminary sample is added to the sample A and stirred to obtain a sample B; acid is added to the sample B to adjust pH, and continuous stirring is performed, so that the metal salt is crystallized into large particles and precipitated; after the solid is separated, deacidification and decolorization treatment is performed, vacuum dehydration and filtration are performed, and a qualified methyl-terminated polyether product is obtained; the intercepted part of the qualified product is used as the preliminary sample for continuous production. The methyl-terminated polyether initial product is added to effectively improve the crystallization process of the metal salt, so that the metal salt tends to form coarse particles which are easy to filter, the filtration resistance is reduced, and the filtration period is shortened.

Description

Technical Field

[0001] This invention belongs to the field of polyether refining technology, specifically relating to a method for refining methyl-terminated polyethers. Background Technology

[0002] Methyl-terminated polyethers, by alkylating the terminal hydroxyl groups on the polyether molecular chain, exhibit unique properties in terms of acid and alkali resistance, heat aging resistance, oil solubility, and chemical stability, and are widely used in various fields such as oils, lubricants, and surfactants. Currently, methyl-terminated polyethers are mainly prepared using the Williamson process. First, a strongly alkaline reagent (sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium hydride, etc.) reacts with the terminal hydroxyl groups of the polyether to form an alkoxide, which then generates an alkoxide anion (ROA). - As a nucleophile, it attacks the carbon atom in a haloalkane (chloromethane, CH3-Cl), replacing the halogen leaving group (Cl). - The polyether bonds (RO-CH3) are formed. For end-capped products with high equivalent molecular weight, due to the long polyether chain and high viscosity, the final reaction product is a mixture of halide (sodium chloride or potassium chloride), end-capped polyether, unreacted strong alkali, and chloromethane emulsion. A complex post-processing procedure is required to obtain a qualified product.

[0003] Currently, the post-processing of alkyl-terminated polyethers mainly involves three methods: one method involves adding a large amount of water to the reaction product to force the salt to dissolve, followed by standing and separating the salt solution to obtain the alkyl-terminated polyether product. Patent CN102516524A describes a post-processing method for alkyl-terminated polyoxypropylene. After polyoxypropylene end-capping, water is added and stirred; after stirring stops, the mixture is allowed to stand and separate; the end-capped polyoxypropylene and brine are separated; water is added a second time to the end-capped polyoxypropylene, and the mixture is stirred; the layers separate again; the mixture is separated again; clay is added to the end-capped polyoxypropylene to remove water; the end-capped polyoxypropylene layer (ether layer) is vacuum dehydrated; after dehydration, the ether layer is filtered to remove the clay, yielding the finished end-capped polyoxypropylene product. The amount of water added each time is 25% to 30% of the weight of the end-capped polyether. Patent CN101235144A describes a method to obtain a capped polyether product by adding approximately 50% by weight of water to the product, allowing it to stand and separate, removing the aqueous phase, vacuum dehydrating, and filtering to remove solid impurities. This method uses a large amount of water and generates a significant amount of saline wastewater, resulting in high production costs and a long production cycle. Another method involves adding acid and water to demulsify the product, allowing the salt to crystallize and separate. This method does not require a large amount of water, but the resulting salt crystals are small, incompletely crystallized, difficult to filter, and the precipitated salts tend to stick together, adhering to equipment and preventing complete removal in one go. To address these issues, patent CN110330640A proposes adding 10-40 wt.% of an azeotropic agent (ethyl acetate, methyltetrahydrofuran, etc.) to the system to increase the width of the metastable region for halide salt crystallization and improve salt crystallinity. However, the azeotropic agent introduced by this method leaves trace amounts in the final product, causing some contamination and potentially limiting downstream applications. The third method involves dissolving the end-capped product with a solvent, precipitating the metal salt, separating it with saturated brine, and finally allowing it to stand for layer separation. Patent CN102276823A describes a method where methyl-terminated allyl alcohol polyoxyethylene ether is dissolved in ethylene glycol ether solvent, washed with a saturated chloride solution, the upper layer is separated, and the solvent and water are removed by vacuum distillation to obtain methyl-terminated allyl alcohol polyoxyethylene. This method uses a large amount of solvent, and also carries the risk of solvent residue contamination of the product. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for refining methyl-terminated polyethers, which solves the problems of incomplete crystallization of metal salts in the existing methyl-terminated polyether refining process, resulting in slow filtration speed and metal salt adhesion to equipment, and ensures that no other components remain in the product.

[0005] The methyl-terminated polyether refining method of the present invention includes the following steps:

[0006] (1) Add water to the methyl-terminated polyether sample to be purified for the first time and stir to dissolve the salt in water and separate the layers. After separation, add water to the polyether layer again and stir. After separation, obtain the preliminary sample.

[0007] (2) Take the methyl-terminated polyether sample to be refined again, heat it, add water, adjust the pH with acid, and continue stirring to obtain sample A;

[0008] (3) Add the preliminary sample to sample A and continue stirring for 0.5h~2h to obtain sample B;

[0009] (4) Add acid to sample B to adjust the pH and stir continuously for 0.5h~2h. At this time, the metal salt crystals will settle as large particles and there will be no adhesion. After separating the solid, the remaining liquid is the crude product. Add adsorbent to the crude product and stir to carry out deacidification and decolorization treatment. Then dehydrate under vacuum and filter again to obtain a colorless and clear qualified methyl-terminated polyether. Retain a portion of the qualified product as a preliminary sample for continuous production.

[0010] The flowchart of the technical solution of the present invention is as follows: Figure 1 As shown.

[0011] The first addition of water and stirring in step (1) refers to adding water at 20%~30% of the mass of the methyl-terminated polyether sample to be refined and stirring for 0.5h~2h. The second addition of water and stirring in step (1) refers to adding water at 20%~30% of the mass of the methyl-terminated polyether sample to be refined and stirring for 0.5h~2h.

[0012] The heating in step (2) is to raise the temperature to 80℃~90℃, and the water added is 3%~5% of the mass of the methyl-terminated polyether sample to be purified.

[0013] The step (2) involves adjusting the pH with acid to 8.0-9.0.

[0014] The acid mentioned in step (2) is phosphoric acid, sulfuric acid, hydrochloric acid, acetic acid, oxalic acid, or citric acid, with phosphoric acid being preferred.

[0015] The amount of preliminary sample added in step (3) is 20% to 40% of the mass of the methyl-terminated polyether sample to be refined in step (2).

[0016] The step (4) of adding acid to adjust the pH is to adjust the pH to 4.5~5.0.

[0017] The adsorbent in step (4) is one or two of magnesium silicate, aluminum silicate, magnesium aluminum silicate, and decolorizing clay. The amount of adsorbent added is 1‰ to 2% of the mass of sample B, preferably 5‰ to 1%.

[0018] The temperature at which the adsorbent is added and stirred in step (4) is 60℃~90℃ and the stirring time is 0.5h~3.0h.

[0019] The vacuum dehydration temperature in step (4) is 105℃~120℃, and the pressure is ≤-0.085MPa.

[0020] The vacuum dehydration time in step (4) is 1h to 3h.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1) The present invention can effectively improve the crystallization process of metal salts by adding methyl-terminated polyether pre-finished product. The principle is that it reduces the concentration of metal salts and widens the metastable region of crystallization. At the same time, methyl-terminated polyether itself is an excellent surfactant, which can reduce interfacial tension, regulate the crystal growth environment, make metal salts tend to form coarse particles that are easy to filter, reduce filtration resistance, and shorten the filtration cycle.

[0023] 2) This invention does not require the introduction of additional substances such as azeotropic agents, and will not cause pollution to the product.

[0024] 3) This invention can effectively inhibit the adhesion of metal salts to equipment, reduce the number of filtrations and improve the first-pass yield of products, while reducing polyether residue and improving product yield.

[0025] 4) This invention retains a portion of qualified products as an additive for the next refining process, thereby achieving continuous production.

[0026] 5) The refining process described in this invention uses little water, does not generate a large amount of saline wastewater, has a short refining cycle, and high production efficiency. Attached Figure Description

[0027] Figure 1 This is a flowchart of the technical solution of the present invention. Detailed Implementation

[0028] The present invention will be further described below with reference to the embodiments.

[0029] Unless otherwise specified, all raw materials used in the examples were commercially available.

[0030] The bleaching clay was purchased from Leping Clean Bleaching Clay Co., Ltd., and its grade is JJ-01.

[0031] Example 1

[0032] Synthesis of methyl-terminated polyethers:

[0033] A. Synthesis of basic polyether oligomers (LMP): At room temperature, 500g of n-butanol and 4.08g of potassium hydroxide catalyst were added to a dry, well-sealed 5L reactor. The reactor was purged three times under positive nitrogen pressure. The temperature was raised to 102.5±2.5℃, and a mixture of 2698.30g of propylene oxide and 674.57g of ethylene oxide was added dropwise. The reaction temperature was 112.5±2.5℃ and the pressure was 0.15±0.15MPa. After the dropwise addition was completed, the temperature was maintained for 2 hours for ripening. The mixture was degassed for 30 minutes and then cooled to 65±5℃ before being discharged.

[0034] B. Synthesis of basic polyether: 670g of oligomer (LMP) and 5.00g of potassium hydroxide catalyst were added to the reactor. After three purgings with nitrogen under positive and negative pressure, the temperature was raised to 107.5±2.5℃ and dehydrated under negative pressure for 1h. Then, a mixture of 2358.40g of propylene oxide and 589.61g of ethylene oxide was added dropwise. The reaction temperature was 112.5±2.5℃ and the pressure was 0.15±0.15MPa. After the dropwise addition was completed, the temperature was maintained for aging for 2h, degassing was performed for 30min, and the temperature was lowered to 65±5℃ before the material was discharged (hydroxyl value 26.6 mg KOH / g) to obtain the basic polyether.

[0035] C. Take 2000 g of the above-mentioned basic polyether into a 3 L batch reactor, add 62.7 g of sodium methoxide solid powder, stir and heat, control the temperature at 110℃, vacuum degree -0.09MPa~-0.1MPa, react for 3 h, then cool to 60℃ and introduce 52.7 g of monochloromethane, react at a constant temperature of 60℃ for 3 h, and remove unreacted monochloromethane to obtain methyl-terminated polyether to be purified.

[0036] The method for refining methyl-terminated polyether includes the following steps:

[0037] (1) Add 100g of water to 500g of methyl-terminated polyether sample to be purified and stir for 0.5h to dissolve the salt in the water. After standing, let the two phases separate. Take the upper clear liquid polyether layer, add 100g of water again and stir for 0.5h. After standing and separating, remove the aqueous phase to obtain the preliminary sample.

[0038] (2) Take another 1000g of the methyl-terminated polyether sample to be refined, stir and heat to 80℃, add 30g of water, adjust the pH of the system to 8.86 with phosphoric acid, continue stirring, and obtain sample A;

[0039] (3) Add 200g of preliminary sample to sample A and continue stirring for 0.5h to obtain sample B;

[0040] (4) Add phosphoric acid to sample B to adjust the pH to 4.63 and stir continuously for 0.5 h. At this time, the metal salt crystals settle as large particles without sticking. After separating the solid, the remaining liquid is the crude product. Add 1.2 g of magnesium aluminum silicate adsorbent to the crude product and stir at 60 °C for 0.5 h for deacidification and decolorization. Then turn on vacuum dehydration. The vacuum dehydration temperature is 105 °C, the pressure is ≤-0.085 MPa, and the dehydration time is 1 h. Then filter to separate the adsorbent, and obtain a colorless and clear qualified methyl-terminated polyether (termination rate 98.7%, Na + The content was 2 ppm, the acid value was 0.023 mg KOH / g, and the moisture content was 0.016 wt.%. A portion of the qualified product was retained as a preliminary sample for continuous production.

[0041] Comparative Example 1

[0042] 1000g of the methyl-terminated polyether sample to be purified in Example 1 was stirred and heated to 80°C. 30g of water was added, and the pH of the system was adjusted to 4.56 with phosphoric acid and stirred for 0.5 h. At this point, the metal salt crystals formed cohesive fine particles that adhered to the equipment. After filtration, 5g of magnesium aluminum silicate adsorbent was added to the liquid phase and stirred at 80°C for 0.5 h for deacidification and decolorization. Then, vacuum dehydration was performed at a temperature of 105°C, a pressure ≤ -0.085 MPa, and a dehydration time of 1 h. Subsequently, the adsorbent was separated by filtration to obtain a clear and transparent finished product (termination rate 98.7%, Na...). + Content 6 ppm, acid value 0.039 mgKOH / g, moisture 0.022 wt.%.

[0043] Example 2

[0044] Synthesis of methyl-terminated polyethers:

[0045] A. Synthesis of basic polyether oligomers (LMP): At room temperature, 350g of methanol and 6.0g of potassium methoxide catalyst were added to a dry, well-sealed 5L reactor. The reactor was purged three times under positive nitrogen pressure. The temperature was raised to 102.5±2.5℃, and 3478.13g of propylene oxide was added dropwise. The reaction temperature was 112.5±2.5℃ and the pressure was 0.15±0.15MPa. After the dropwise addition was completed, the temperature was maintained for 2 hours for maturation. The mixture was degassed for 30 minutes and then cooled to 65±5℃ before being discharged.

[0046] B. Synthesis of basic polyether: After the above polyether is purified and desalted, 500g is added to a reaction vessel, along with 30 ppm DMC bimetallic catalyst and 15 ppm sulfuric acid. After pre-dropping propylene oxide to initiate the system, a total of 2695.61 g of propylene oxide is continuously introduced. The reaction temperature is 127.5±2.5℃ and the pressure is 0.05±0.05 MPa. After the droplet addition is completed, the temperature is maintained for 2 h for ripening, followed by degassing for 30 min. The mixture is then cooled to 65±5℃ and discharged to obtain the basic polyether (hydroxyl value 34.6 mg KOH / g).

[0047] C. Synthesis of methyl-terminated polyether: 2000 g of the above-mentioned basic polyether was placed in a 3 L batch reactor, 80.0 g of sodium methoxide solid powder was added, and the mixture was stirred and heated. The temperature was controlled at 120℃, and the vacuum degree was -0.09 MPa to -0.1 MPa. The reaction was carried out for 3 h, and then cooled to 70℃. 67.9 g of monochloromethane was introduced, and the reaction was carried out at a constant temperature of 70℃ for 5 h. After removing unreacted monochloromethane, crude methyl-terminated polyether was obtained.

[0048] The method for refining methyl-terminated polyether includes the following steps:

[0049] (1) Add 130 g of water to 500 g of methyl-terminated polyether sample to be refined and stir for 1.5 h to dissolve the salt in the water. After standing, let the two phases separate. Take the upper clear liquid polyether layer, add 130 g of water again and stir for 1.5 h. After standing and separating, remove the aqueous phase to obtain the preliminary sample.

[0050] (2) Take another 1000g of the methyl-terminated polyether sample to be refined, stir and heat to 85°C, add 40g of water, adjust the pH of the system to 8.91 with phosphoric acid, continue stirring, and obtain sample A;

[0051] (3) Add 330 g of preliminary sample to sample A and continue stirring for 2 h to obtain sample B;

[0052] (4) Add phosphoric acid to sample B to adjust the pH to 4.59 and stir continuously for 2 hours. At this time, the metal salt crystals settle as large particles without sticking. After separating the solid, the remaining liquid is the crude product. Add 6.5 g of magnesium silicate and 5 g of decolorizing clay adsorbent to the crude product and stir at 80°C for 2 hours to perform deacidification and decolorization treatment. Then turn on vacuum dehydration. The vacuum dehydration temperature is 110°C, the pressure is ≤-0.085MPa, and the dehydration time is 2 hours. Then filter to separate the adsorbent to obtain a colorless and clear qualified methyl-terminated polyether (termination rate 97.1%, Na + The content was 1 ppm, the acid value was 0.036 mg KOH / g, and the moisture content was 0.019 wt.%. A portion of the qualified product was retained as a preliminary sample for continuous production.

[0053] Example 3

[0054] Synthesis of methyl-terminated polyethers:

[0055] A. Synthesis of basic polyether: At room temperature, 360g of allyl alcohol and 5.3g of sodium methoxide catalyst were added to a dry, well-sealed 5L reactor. The reactor was purged three times under positive nitrogen pressure. The temperature was raised to 102.5±2.5℃, and a mixture of 1530g of propylene oxide and 1530g of ethylene oxide was added dropwise. The reaction temperature was 120±2.5℃ and the pressure was 0.15±0.15MPa. After the dropwise addition was completed, the temperature was maintained for 2 hours for ripening. After degassing for 30 minutes, the temperature was lowered to 65±5℃ and the material was discharged to obtain the basic polyether (hydroxyl value 102.6 mgKOH / g).

[0056] B. Synthesis of methyl-terminated polyether: 2000 g of the above-mentioned basic polyether was placed in a 3 L batch reactor, 153.6 g of sodium hydroxide solid powder was added, and the mixture was stirred and heated. The temperature was controlled at 110℃, and the vacuum degree was -0.09 MPa to -0.1 MPa. The reaction was carried out for 3 h, and then cooled to 80℃. 203 g of chloromethane was introduced, and the reaction was carried out at a constant temperature of 80℃ for 5 h. After removing unreacted chloromethane, crude methyl-terminated polyether was obtained.

[0057] The method for refining methyl-terminated polyether includes the following steps:

[0058] (1) Add 150g of water to 500g of methyl-terminated polyether sample to be refined and stir for 2h to dissolve the salt in the water. After standing, let the two phases separate. Take the upper clear liquid polyether layer, add 150g of water again and stir for 2h. After standing and separating, remove the aqueous phase to obtain the preliminary sample.

[0059] (2) Take another 1000g of the methyl-terminated polyether sample to be refined, stir and heat to 90℃, add 50g of water, adjust the pH of the system to 8.33 with phosphoric acid, continue stirring, and obtain sample A;

[0060] (3) Add 400g of preliminary sample to sample A and continue stirring for 2 hours to obtain sample B;

[0061] (4) Add phosphoric acid to sample B to adjust the pH to 4.86 and stir continuously for 2 hours. At this time, the metal salt crystals settle as large particles without sticking. After separating the solid, the remaining liquid is the crude product. Add 12g of aluminum silicate and 16g of magnesium silicate adsorbent to the crude product and stir at 90℃ for 3 hours to perform deacidification and decolorization treatment. Then turn on vacuum dehydration. The vacuum dehydration temperature is 120℃, the pressure is ≤-0.085MPa, and the dehydration time is 3 hours. Then filter to separate the adsorbent to obtain a colorless and clear qualified methyl-terminated polyether (termination rate 99.1%, Na +The content was 2 ppm, the acid value was 0.029 mg KOH / g, and the moisture content was 0.013 wt.%. A portion of the qualified product was retained as a preliminary sample for continuous production.

Claims

1. A method for refining a methyl-terminated polyether, characterized by, It comprises the following steps: (1) first add water to the methyl-terminated polyether sample to be refined, stir, and make the salt dissolve in water, then separate the layers, add water to the polyether layer again, stir, and separate after the layers are separated to obtain a preliminary sample; (2) take the methyl-terminated polyether sample to be refined again, heat, add water, adjust the pH with acid, continue to stir, and obtain sample A; (3) add the preliminary sample to sample A, continue to stir, and obtain sample B; (4) adjust the pH of sample B with acid, and continue to stir, at this time, the metal salt crystallizes into large particles and settles, after the solid is separated, the liquid is left as a crude product, an adsorbent is added to the crude product and stirred, and deacidification and decolorization treatment is performed, then vacuum dehydration is performed, and the methyl-terminated polyether qualified product is obtained after filtration again, the intercepted part of the qualified product is used as the preliminary sample for continuous production; The pH adjustment with acid in step (2) is to adjust the pH to 8.0-9.0; The pH adjustment with acid in step (4) is to adjust the pH to 4.5-5.0; The amount of the preliminary sample added in step (3) is 20%-40% of the mass of the methyl-terminated polyether sample to be refined in step (2).

2. The methyl-terminated polyether finishing process of claim 1, wherein, The first water stirring in step (1) is to add 20%-30% of the mass of the methyl-terminated polyether sample to be refined and stir for 0.5-2 h, and the second water stirring in step (1) is to add 20%-30% of the mass of the methyl-terminated polyether sample to be refined and stir for 0.5-2 h.

3. The methyl-terminated polyether finishing process of claim 1, wherein, The heating in step (2) is to heat to 80-90℃, and the water added in step (2) is 3%-5% of the mass of the methyl-terminated polyether sample to be refined.

4. The methyl-terminated polyether finishing process of claim 1, wherein, The adsorbent in step (4) is one or two of magnesium silicate, aluminum silicate, magnesium aluminum silicate, and decolorizing clay, and the amount of the adsorbent added is 1‰-2% of the mass of sample B.

5. The methyl-terminated polyether finishing process of claim 1, wherein, The temperature for adding the adsorbent and stirring in step (4) is 60-90℃, and the stirring time is 0.5-3.0 h.

6. The methyl-terminated polyether finishing process of claim 1, wherein, The temperature for vacuum dehydration in step (4) is 105-120℃, and the pressure is ≤-0.085 MPa.

7. The methyl-terminated polyether finishing process of claim 1, wherein, The time for vacuum dehydration in step (4) is 1-3 h.

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