Preparation method of narrow-distribution high-carbon alcohol polyoxyether

Abstract

The invention discloses a preparation method of narrow-distribution high-carbon alcohol polyoxyethylene ether, which comprises the following steps: in inert gas, under the action of a catalyst, sequentially carrying out first-stage reaction, second-stage reaction,..., and Nth-stage reaction on raw materials and epoxy alkyl, N is a natural number greater than 2, the temperature of each stage of reaction is sequentially increased, the temperature of the Nth-stage reaction is 110 DEG C, and the temperature of the Nth-stage reaction is 30 DEG C; when the reaction in each stage begins, the epoxy alkyl and the catalyst are supplemented and added; the temperature of the first-stage reaction is higher than the melting point of the raw materials; the raw material is C20-C32 high alcohol, and the catalyst is organic alkali. According to the invention, by gradually heating and controlling the addition rate of epoxy alkyl, PDI can be ensured to be less than 1.5 and even less than 1.2, narrow distribution is achieved, and the content of free PEG is less than or equal to 0.5% by mass. The prepared narrow-distribution high-carbon alcohol polyoxyether is uniform in chain length and consistent in characteristics, is suitable for the fields of surfactants, lubricants, emulsifiers and the like, and is superior to traditional distribution products in performance.

Description

Technical Field

[0001] This invention belongs to the field of fatty alcohol polyether technology, specifically relating to a method for preparing high carbon alcohol polyoxyethylene. Background Technology

[0002] Higher alcohol polyoxyethylene ethers (addition products of C20-C32 alcohols and ethylene oxide or propylene oxide) are an important class of nonionic surfactants widely used in daily chemicals, textiles, and pesticide emulsification. Traditional synthesis methods typically employ alkaline catalysts (such as potassium hydroxide and sodium hydroxide) to catalyze the alkoxylation reaction of higher alcohols with ethylene oxide (EO) and propylene oxide (PO). Higher alcohols have high melting points and require high temperatures (>100℃) to maintain a liquid state for the reaction, while alkyl ethers are prone to side reactions such as self-polymerization and chain scission at high temperatures. However, samples exhibit poor flowability at low temperatures, leading to excessively high local catalyst concentrations and uneven reaction, resulting in an uneven distribution of EO / PO addition numbers and a high product molecular weight dispersion (PDI) (typically PDI>1.5), affecting the stability of emulsification, wetting, and other properties. Competitive adsorption of components with different degrees of polymerization in the broadly distributed products leads to poor emulsion stability and uncontrollable foaming properties, making it difficult to meet the uniformity requirements of high-end applications (such as pharmaceutical carriers and cosmetic emulsifiers). Therefore, after solving the flowability problem, the remaining catalyst needs to be added to reduce the molecular weight dispersion of the product.

[0003] Chinese patent CN109679085B discloses a narrow-distribution random polyether and its preparation method. The method involves a stepwise catalytic process to prepare the narrow-distribution random polyether. A first reaction mixture is obtained by mixing an initiator containing active hydrogen and a first catalyst. At least two epoxides are then added to the heated first reaction mixture to obtain a second reaction mixture. After aging and vacuum degassing, a narrow-distribution random polyether intermediate is obtained. The narrow-distribution random polyether intermediate and a second catalyst are then mixed to obtain a third reaction mixture. At least two epoxides are then added to the heated third reaction mixture to obtain a fourth reaction mixture. After aging and vacuum degassing, the narrow-distribution random polyether is obtained. The product has a molecular weight distribution coefficient of less than 1.06. However, this method has a long aging time during intermediate preparation and a relatively cumbersome preparation process, which prolongs the reaction cycle and increases production costs. Chinese patent application CN106084197A reports a method for preparing narrow distribution polyethers. By using a composite catalyst and controlling the reaction temperature and time, the polymerization of small molecule alcohols such as ethylene glycol with propylene oxide is catalyzed to prepare narrow distribution polyethers. However, this process is not suitable for catalyzing ethylene oxide systems, mainly because bimetallic cyanide catalysis of ethylene oxide easily generates high molecular weight components, which reduces the overall performance of the product and makes it prone to stratification, which is not conducive to downstream applications.

[0004] Therefore, there is an urgent need to develop a simple and cost-controllable method for preparing narrow-distribution high-carbon alcohol polyoxyethylene, which can achieve high reaction efficiency and precise control of product molecular weight distribution under mild conditions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing narrow-distribution high-carbon alcohol polyoxyethylene ethers. This method achieves efficient and controllable addition of high-carbon alcohols to epoxyalkanes (ethylene oxide or propylene oxide) under low-temperature conditions, significantly reducing the molecular weight dispersion of the product (PDI < 1.2) while avoiding side reactions such as self-polymerization and chain scission of epoxyalkanes. This invention uses sodium methoxide or potassium methoxide as a catalyst, and the generated methanol can replace the water produced by traditional sodium hydroxide and potassium hydroxide, effectively reducing the presence of free PEG (≤0.5%) and meeting the application requirements of high-end surfactants.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a narrow-distribution high-carbon alcohol polyoxyethylene includes: in an inert gas, under the action of a catalyst, the raw material and an epoxy alkane are sequentially subjected to a first-stage reaction, a second-stage reaction, ... a Nth-stage reaction, where N is a natural number greater than 2, the temperature of each stage of the reaction is successively increased, the temperature of the Nth-stage reaction is 110°C, and at the beginning of each stage of the reaction, an epoxy alkane and a catalyst are added. The temperature of the first stage reaction is higher than the melting point of the raw material; The raw material is a C20~C32 high carbon alcohol, and the catalyst is an organic base.

[0007] Preferably, the higher alcohol is peanut alcohol, behenol, wood wax alcohol, wax alcohol, montanol, beeswax alcohol or insect wax alcohol.

[0008] Preferably, the organic base is one or a mixture of two of sodium methoxide or potassium methoxide.

[0009] Preferably, the epoxy alkane is ethylene oxide (EO) or propylene oxide (PO).

[0010] Preferably, N is 2 or 3.

[0011] Preferably, the amount of epoxide added in the first stage reaction is 1 to 5 times the molar number of the higher alcohol, and the amount of epoxide added in each stage reaction increases sequentially.

[0012] Preferably, the total mass of catalyst added in all stages of the reaction is 0.2% to 1% of the mass of the raw materials.

[0013] Preferably, the mass of the catalyst added in the first stage reaction is 0.01% to 0.1% of the mass of the raw materials.

[0014] Preferably, the temperature of the first stage reaction is 70~90℃.

[0015] Preferably, the preparation method further includes the steps of neutralizing the catalyst and removing unreacted epoxides after the Nth stage reaction is completed.

[0016] Preferably, the preparation method further includes monitoring the degree of polymerization using hydroxyl value. Referring to the national standard GB / T 7383-2020, this method is suitable for determining the hydroxyl value of nonionic surfactants. This standard adopts the international standard ISO 4326:1980, mainly using the acetic anhydride method and the phthalic anhydride method for determination, applicable to hydroxyl values ​​in the range of 10~1000, with simple process and high efficiency.

[0017] This invention achieves a controllable reaction rate by adding epoxide-containing alkane in stages and the remaining catalyst in batches, with the temperature gradually increased to 110°C after each addition. Ultimately, it reaches n degrees of polymerization, with polymer molecular weights of: propylene oxide corresponds to n*44+ higher alcohol molecular weights, and propylene oxide corresponds to n*58+ higher alcohol molecular weights.

[0018] This invention, by gradually increasing the temperature and controlling the addition rate of the epoxy alkane, can ensure a polydispersity index (PDI) of <1.5, or even less than 1.2, achieving a narrow distribution, and making the free PEG content ≤0.5% by mass fraction.

[0019] In the preparation method provided by this invention, as the carbon chain grows, the amount of epoxy alkane added gradually increases, which can lower the melting point of subsequent reactions.

[0020] This invention utilizes a segmented preparation method to produce narrowly distributed high-carbon alcohol polyoxyethylene with uniform chain length and consistent properties. It is suitable for applications such as surfactants, lubricants, and emulsifiers, and its performance is superior to that of traditionally distributed products. Detailed Implementation

[0021] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto.

[0022] The calculation of the hydroxyl value in the examples is shown in Formula 1: Hydroxyl value = 56100 / polymer molecular weight (Formula 1).

[0023] Example 1: Preparation of peanut alcohol polyoxypropyl ether-20 Add 1.0 mol (298.5 g) of peanut alcohol and 0.15 g of potassium methoxide to a pressure reactor. Pour N2 into the reactor to 200-400 kPa and maintain this pressure for 15 minutes without leakage. Then, evacuate the reactor and replace the PO with N2 three times (≤-96 kPa), and close the N2 valve. Slowly raise the temperature to 70°C under slight positive pressure, start stirring at 400 r / min, and close the vacuum valve and vacuum system. Slowly introduce 5 mol (290.0 g) of propylene oxide. After the PO is completely introduced, close the feed inlet and maintain the temperature for 1 hour to absorb the remaining epoxides. After the reaction is complete, add 1.34 g of potassium methoxide, then introduce the remaining 15 mol (870.0 g) of propylene oxide at a feed rate of 3 g / min. Slowly raise the temperature to 110°C and maintain this temperature for 2 hours to absorb the remaining epoxides, neutralize, evacuate the reactor, close the vacuum system, and cool the reactor to below 80°C to obtain the peanut alcohol polyoxypropylene ether-20 product.

[0024] Example 2 Preparation of behenol polyoxypropyl ether-20 Add 1.0 mol (326.6 g) behenol and 0.16 g potassium methoxide to a pressure reactor. Pour N2 into the reactor to 200-400 kPa and maintain this pressure for 15 minutes without leakage. Then, evacuate the reactor and replace the N2 pressure three times (≤-96 kPa), before closing the N2 valve. Slowly raise the temperature to 75°C under slight positive pressure, start stirring at 400 r / min, and close the vacuum valve and vacuum system. Slowly introduce 5 mol (290.0 g) propylene oxide. After the PO is introduced, close the feed inlet and maintain the temperature for 1 hour to absorb the remaining epoxides. After the reaction is complete, add 1.48 g potassium methoxide and introduce the remaining 15 mol (870.0 g) propylene oxide at a feed rate of 3 g / min. Slowly raise the temperature to 110°C and maintain this temperature for 2 hours to absorb the remaining epoxides, neutralize, evacuate the reactor, close the vacuum system, and cool the reactor to below 80°C to obtain the behenol polyoxypropylene ether-20 product.

[0025] Example 3 Preparation of behenol polyoxypropyl ether-100 Add 1.0 mol (326.6 g) behenol and 0.16 g potassium methoxide to a pressure reactor. Pour N2 into the reactor to 200-400 kPa, maintaining this pressure for 15 minutes without leakage. Then, evacuate the reactor three times with N2 (≤-96 kPa) and close the N2 valve. Slowly raise the temperature to 75°C under slight positive pressure, start stirring at 400 rpm, and close the vacuum valve and vacuum system. Slowly introduce 5 mol (290.0 g) propylene oxide. After the PO is introduced, close the feed inlet and maintain the temperature for 1 hour to absorb the remaining epoxides. After the reaction is complete, add 0.74 g potassium methoxide a second time, and slowly introduce 40 mol (2320.0 g) propylene oxide. After the PO is introduced, close the feed inlet and maintain the temperature for 1 hour to absorb the remaining epoxides. After the reaction was complete, 0.74 g of potassium methoxide was added for the third time, and the remaining 45 mol (2610.0 g) of propylene oxide was introduced at a feed rate of 3 g / min. The temperature was slowly raised to 110 °C and held for 2 hours to absorb the remaining epoxides, neutralize, and then vacuum the system. The vacuum system was then turned off, and the product was discharged at a temperature below 80 °C to obtain behenyl alcohol polyoxypropylene ether-100.

[0026] Example 4: Preparation of wood wax alcohol polyoxypropyl ether-170 Add 1.0 mol (354.7 g) of wood wax alcohol and 0.16 g of potassium methoxide to a pressure reactor. Pour N2 into the reactor to 200-400 kPa, maintaining this pressure for 15 minutes without leakage. Then, evacuate the reactor three times with N2 (≤-96 kPa) and close the N2 valve. Slowly raise the temperature to 75℃ under slight positive pressure, start stirring at 400 rpm, and close the vacuum valve and vacuum system. Slowly introduce 5 mol (290.0 g) of propylene oxide. After the PO is introduced, close the feed inlet and maintain the temperature for 1 hour to absorb the remaining epoxides. After the reaction is complete, add 1.56 g of potassium methoxide a second time, and slowly introduce 80 mol (4646.4 g) of propylene oxide. After the PO is introduced, close the feed inlet and maintain the temperature for 1 hour to absorb the remaining epoxides. After the reaction was complete, 1.56 g of potassium methoxide was added for the third time, and the remaining 85 mol (4936.8 g) of propylene oxide was introduced at a feed rate of 3 g / min. The temperature was slowly raised to 110 °C and held for 2 h to absorb the remaining epoxides, neutralize, and then vacuum the system. The vacuum system was then turned off and the temperature was lowered to below 80 °C to discharge the product, which was wood wax alcohol polyoxypropylene ether-170.

[0027] Example 5: Preparation of insectoyl alcohol polyoxyethyl ether-11 Add 1.0 mol (466.8 g) of insectohydrin and 0.05 g of sodium methoxide to a pressure reactor. Pour N2 into the reactor to 200-400 kPa, maintaining this pressure for 15 minutes without leakage. Then, evacuate the reactor and replace the N2 pressure three times (≤-96 kPa), before closing the N2 valve. Slowly raise the temperature to 90°C under slight positive pressure, start stirring at 400 rpm, and close the vacuum valve and vacuum system. Slowly introduce 1 mol of ethylene oxide. After the EO is completely introduced, close the feed inlet and maintain the temperature for 1 hour to absorb the remaining epoxides. After the reaction is complete, add 0.88 g of potassium methoxide a second time, and slowly introduce 10 mol of ethylene oxide at a feed rate of 3 g / min. Slowly raise the temperature to 110°C and maintain this temperature for 2 hours to absorb the remaining epoxides, neutralize, evacuate the reactor, close the vacuum system, and cool the temperature to below 80°C before discharging to obtain the finished product.

[0028] Example 6: Preparation of Bee Flower Alcohol Polyoxyethyl Ether-12 Add 1.0 mol (438.8 g) of beeswax alcohol and 0.44 g of sodium methoxide to a pressure reactor. Pour N2 into the reactor to 200-400 kPa, maintaining this pressure for 15 minutes without leakage. Then, evacuate the reactor and replace the N2 pressure three times (≤-96 kPa), before closing the N2 valve. Slowly raise the temperature to 90°C under slight positive pressure, start stirring at 400 rpm, and close the vacuum valve and vacuum system. Slowly introduce 2 mol of ethylene oxide. After the EO is completely introduced, close the feed inlet and maintain the temperature for 1 hour to absorb the remaining epoxides. After the reaction is complete, add 1.75 g of sodium methoxide a second time, and slowly introduce 10 mol of ethylene oxide at a feed rate of 3 g / min. Slowly raise the temperature to 110°C and maintain this temperature for 2 hours to absorb the remaining epoxides, neutralize, evacuate the reactor, close the vacuum system, and cool the temperature to below 80°C before discharging to obtain the finished product.

[0029] Comparative Example 1: Preparation of Peanut Alcohol Polyoxypropyl Ether-20 Add 1.0 mol (298.5 g) of peanut alcohol and 1.49 g of potassium methoxide to a pressure reactor. Pour N2 into the reactor to 200-400 kPa and maintain this pressure for 15 minutes without leakage. Then, evacuate the reactor and replace the pressure with N2 three times (≤-96 kPa), and close the N2 valve. Slowly raise the temperature to 70°C under slight positive pressure, start stirring at 400 rpm, and close the vacuum valve and vacuum system. Slowly introduce 20 mol (986.0 g) of propylene oxide. After the PO is introduced, close the feed inlet. Slowly raise the temperature to 110°C and hold for 2 hours to absorb the remaining epoxides and neutralize the epoxides. Evacuate the reactor, close the vacuum system, and cool the reactor to below 80°C to obtain the peanut alcohol polyoxypropylene ether-20 product.

[0030] Comparative Example 2: Preparation of behenyl alcohol polyoxypropyl ether-20 Add 1.0 mol (326.6 g) behenol and 1.64 g potassium methoxide to a pressure reactor. Pour N2 into the reactor to 200-400 kPa and maintain this pressure for 15 minutes without leakage. Then, evacuate the reactor and replace the N2 pressure three times (≤-96 kPa), and close the N2 valve. Slowly raise the temperature to 75°C under slight positive pressure, start stirring at 400 r / min, and close the vacuum valve and vacuum system. Slowly introduce 20 mol (1160.0 g) propylene oxide. After the PO is introduced, close the feed inlet. Slowly raise the temperature to 110°C and hold for 2 hours to absorb the remaining epoxides, neutralize, evacuate the reactor, close the vacuum system, and cool the reactor to below 80°C to obtain the behenol polyoxypropylene ether-20 product.

[0031] Comparative Example 3: Preparation of behenyl alcohol polyoxypropyl ether-20 Add 1.0 mol (326.6 g) behenol and 1.64 g potassium methoxide to a pressure reactor. Pour N2 into the reactor to 200-400 kPa and maintain this pressure for 15 minutes without leakage. Then, evacuate the reactor and replace the N2 pressure three times (≤-96 kPa), and close the N2 valve. Increase the temperature directly to 110℃ under slight positive pressure and start stirring at 400 r / min. Close the vacuum valve and vacuum system. Slowly introduce 20 mol (1160.0 g) propylene oxide. After the PO is introduced, close the feed inlet. Maintain the temperature for 2 hours to absorb the remaining epoxides, neutralize, evacuate the reactor, close the vacuum system, and cool to below 80℃ before discharging to obtain the behenol polyoxypropylene ether-20 product.

[0032] Table 1. Detection data of the higher alcohol polyoxypropylene ethers prepared in Examples 1-4 and Comparative Examples 1-3 Degree of polymerization of propylene oxide Hydroxyl value / mgKOH / g Polymer Dispersion Index (PDI) Free PEG content / % Example 1 20 38 1.08 Not detected Example 2 20 37 1.08 Not detected Example 3 100 9 1.09 0.01 Example 4 170 5.5 1.10 0.01 Comparative Example 1 20 38 1.28 Not detected Comparative Example 2 20 38 1.29 Not detected Comparative Example 3 20 37 1.58 4.8

[0033] As can be seen from the table above, the high-carbon alcohol polyoxyethylene products synthesized using the preparation method provided by this invention have a narrow molecular weight distribution (PDI < 1.2), free PEG content ≤ 0.5%, and the actual detected hydroxyl value is consistent with the theoretically calculated hydroxyl value.

[0034] Although the above examples have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a narrowly distributed high-carbon alcohol polyoxyethylene, characterized in that, include: In an inert gas atmosphere, under the action of a catalyst, the raw material and the epoxy alkane undergo a first-stage reaction, a second-stage reaction, and so on up to the Nth-stage reaction, where N is a natural number greater than 2. The temperature of each stage of the reaction increases sequentially, with the temperature of the Nth-stage reaction being 110°C. At the beginning of each stage of the reaction, epoxy alkane and catalyst are added. The temperature of the first stage reaction is higher than the melting point of the raw material; The raw material is a C20~C32 high carbon alcohol, and the catalyst is an organic base.

2. The preparation method according to claim 1, characterized in that, The higher alcohols are peanut alcohol, behenol, wood wax alcohol, wax alcohol, montanol, beeswax alcohol, or insect wax alcohol.

3. The preparation method according to claim 1, characterized in that, The organic base is one or a mixture of two of sodium methoxide or potassium methoxide.

4. The preparation method according to claim 1, characterized in that, The epoxy alkane is ethylene oxide or propylene oxide.

5. The preparation method according to claim 1, characterized in that, N is 2 or 3.

6. The preparation method according to claim 1, characterized in that, The amount of epoxide added in the first stage of the reaction is 1 to 5 times the molar number of the higher alcohol, and the amount of epoxide added in each stage of the reaction increases sequentially.

7. The preparation method according to claim 1, characterized in that, The total mass of catalyst added in all stages of the reaction is 0.2% to 1% of the mass of the raw materials.

8. The preparation method according to claim 1, characterized in that, The mass of the catalyst added in the first stage reaction is 0.01% to 0.1% of the mass of the raw materials.

9. The preparation method according to claim 1, characterized in that, The temperature of the first stage reaction is 70~90℃.

10. The preparation method according to claim 1, characterized in that, The preparation method also includes monitoring the degree of polymerization using hydroxyl value.