Preparation method of narrow-distribution polyether polyol

Abstract

The invention discloses a preparation method of narrow-distribution polyether polyol. The method disclosed by the invention is simple in process, few in side reaction, high in product yield, continuous in production and capable of greatly reducing the cost. In addition, the polyether polyol product is narrow in molecular weight distribution, and the applicability is improved. The polyether polyol can be used in the fields of polyurethane, coatings, adhesives, sealants and rubber.

Description

Technical Field

[0001] The invention belongs to the technical field of polyether polyol preparation, and in particular relates to a method for preparing narrow distribution polyether polyol. Background Art

[0002] Polyether polyol is a nonionic surfactant with an active polyether bond structure and good surface activity. It can be added with active hydrogen or copolymerized with unsaturated compounds to give the product good lubrication, softening effect, good spreadability and stable emulsification. It can be widely used in many fields such as water reducers for construction, polyurethane soft or hard foaming agents, agricultural organic silicon synergists, low-foam detergents, lubricants, textiles, etc., with great market capacity and potential. It is increasingly used in various fields, such as automobiles, furniture, clothing and other industries.

[0003] Since the bimetallic preparation process of polyether polyols was developed by General Motors in the United States in the 1960s, polyether polyols have been widely used. Polyether polyols synthesized by bimetallic catalysis have attracted wide attention due to their advantages such as high relative molecular mass, narrow relative molecular mass distribution, and low unsaturation.

[0004] Glycerol is the most commonly used initiator, but propylene glycol (MPG), sorbitol and sucrose are also used. Propylene oxide (PO) is mainly used as an addition monomer, sometimes in combination with small amounts of ethylene oxide (EO) to improve product properties.

[0005] At present, the production of polyether polyols adopts the indirect method, which has complex processes, low conversion rates, and many by-products, resulting in poor product quality, which is far from meeting the needs of the future market.

[0006] The patent application with publication number US3278458A describes the preparation process of bimetallic polyol (DMC) in detail. DMC catalyst can be represented by the general formula M a [M1(CN) b A c ]·xMXn·yH2O·zR indicates that M mainly refers to Zn in transition metals 2+ , Fe 2+ ; M1 mainly refers to Fe in transition metals 3+ 、Co 3+ , Ir 3+ etc.; A, X are selected from halogen anions, NCO – OH – , CN – 、SO4 2 –A and X can be the same or different, A can also be a neutral small molecule such as CO, H2O, etc.; R is an organic ligand, usually a water-soluble compound containing heteroatoms, such as alcohol, ketone, ether, amide, urea, nitrile, sulfide, etc. However, this method requires post-reaction treatment operations such as neutralization, and usually has a large number of by-products, which brings difficulties to product separation, catalyst recovery and wastewater treatment, thereby complicating the process equipment and increasing the requirements for equipment anti-corrosion performance. Summary of the invention

[0007] The object of the present invention is to provide a method for preparing narrow distribution polyether polyols.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] The first aspect of the present invention provides a method for preparing a narrow distribution polyether polyol, comprising the following steps:

[0010] The temperature of the catalyst slurry preparation kettle is adjusted to <40°C, a mixed initiator and a main catalyst are added, or a mixed initiator, a co-catalyst and a main catalyst are added, and the catalyst slurry is evenly stirred to obtain the catalyst slurry, which enters the main reaction kettle, and the temperature is adjusted to 40°C to 80°C (preferably 70°C), and the vacuum is evacuated for at least half an hour, and the gas is replaced with nitrogen. When the temperature in the main reaction kettle is raised to 15-120°C (preferably 110-115°C), ethylene oxide (EO) and A mixture of propylene oxide (PO), the temperature of the mixture is 5 to 15 ° C (preferably 10 ° C), the pressure in the main reactor is maintained at ≤ 0.5 MPa during the dropwise addition, after the dropwise addition is completed, the aging is performed for 1 to 2 hours, and the mixture of ethylene oxide (EO) and propylene oxide (PO) with a mass ratio of 1: 1 to 15 (preferably 1: 9) is continued to be dropped into the main reactor, and the pressure in the main reactor is maintained at ≤ 0.5 MPa. When the dropwise addition amount meets the requirements, the circulation system is opened for 1 to 5 hours (preferably 2 to 3 hours). ), then turn on the tubular aging reactor, adjust the flow rate of the circulation system to the flow rate of the tubular aging reactor to be 30-50 (preferably 40), and add this part of the material according to the mass ratio of the sum of the mass of the mixed initiator and the main catalyst to the sum of the mass of ethylene oxide (EO) and propylene oxide (PO) of 1:50-80 (preferably 1:60, 1:75, 1:80), or, according to the mass ratio of the sum of the mass of the mixed initiator, the co-catalyst and the main catalyst to the sum of the mass of ethylene oxide (EO) and propylene oxide (PO) The mass ratio of the sum of the masses is 1:50-80 (preferably 1:60, 1:75, 1:80). This part of the material is added, and the sum of the masses of ethylene oxide (EO) and propylene oxide (PO) includes the sum of all the masses of ethylene oxide (EO) and propylene oxide (PO) added in the reaction; so that the material balance is achieved to form a continuous production process; the circulating material enters the main reactor, and the discharge from the tubular aging reactor passes through a devolatilization tower, nitrogen blows off trace impurities, and then is filtered to obtain the narrow distribution polyether polyol.

[0011] The mass percentage of the main catalyst to the mixed initiator is 0.01-1% (preferably 0.28%, 0.3%).

[0012] The mass percentage of the co-catalyst to the mixed initiator is 0.0001-0.8% (preferably 0.02%).

[0013] The mass of the mixed initiator accounts for 0.5-5% (preferably 1.3%, 1.66%, 1.25%, 1.33%) of the sum of the masses of ethylene oxide (EO) and propylene oxide (PO), and the sum of the masses of ethylene oxide (EO) and propylene oxide (PO) includes the sum of all masses of ethylene oxide (EO) and propylene oxide (PO) added in the reaction.

[0014] The main catalyst is selected from at least one of SnCl2, SnCl4, SnO, and SnO2.

[0015] The co-catalyst is BX3, X is selected from F, Cl, Br, I; preferably BF3.

[0016] The mixed initiator is selected from at least one of glycerol, methyl methacrylate, propylene glycol, sorbitol, sucrose, pentaerythritol, diethylene glycol, propylene glycol, glycerol, monoethanolamine, diethanolamine, triethanolamine, urea and methyl acrylate.

[0017] The polyether polyol has a hydroxyl value of 350-970 mKOH / kg (preferably 410, 420, 430, 446, 470, 525 mKOH / kg), a viscosity of 1000-4000 CP / 25°C (preferably 1430, 2685, 2990, 3050, 3230 cp / °C), a moisture content of ≤0.07% (preferably 0.05%, 0.06%, 0.07%), and a pH of 6.7-7.1 (preferably 6.7, 6.8, 6.9, 7, 7.1).

[0018] The conversion rate of ethylene oxide (EO) and propylene oxide (PO) is greater than 99.9%.

[0019] The theoretical molecular weight of the polyether polyol is 1000-8000 (preferably 8000, 7500, 7000, 6000, 7200, 5500), and the actual molecular weight is 800-8000 (preferably 7962, 7450, 6972, 5905, 7115, 5380).

[0020] The molecular weight distribution index PDI of the polyether polyol is 1 to 1.2 (preferably 1.0895, 1.0640, 1.1184, 1.1267, 1.1390, 1.0425).

[0021] The unsaturation degree of the polyether polyol is 0 or 1.

[0022] Due to the adoption of the above technical solution, the present invention has the following advantages and beneficial effects:

[0023] The catalyst used in the method of the present invention has very high activity, selectivity, and favors the growth of short chains rather than long chains. The amount of catalyst used is small, and because the concentration is low and neutral, there is no need to remove the catalyst from the reaction product as in the conventional KOH process. The high selectivity results in a low impurity content in the reaction product, usually below 60 ppm wt%.

[0024] The method of the invention has simple process, few side reactions, high product yield, continuous production, and greatly reduced costs; in addition, the molecular weight distribution of the polyether polyol product is narrow, and the applicability is improved. The polyether polyol can be used in the fields of polyurethane, coatings, adhesives, sealants and rubber.

[0025] Compared with the conventional KOH process technology, the method of the present invention has the following advantages: less equipment is required, thereby reducing investment costs; the conversion rate of EO / PO is higher, achieving a final conversion rate of greater than 99.9%, and reducing organic waste emissions; the ppm-level high-activity catalyst used is retained in the product, so that no catalyst waste is generated at the same time except for a very small amount of catalyst waste filtered out from the product.

[0026] The method of the present invention is more energy efficient than the KOH process, without many energy-intensive evaporation steps. The lower level of impurities in the reaction product combined with the removal steps results in a product that is superior in terms of odor, composition and volatility of organic components.

[0027] The continuous operation mode of the method of the present invention has higher reliability than the KOH process and is safer because the PO concentration in the reactor is lower in a stable state, usually about 1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the device used in the present invention.

[0029] Among them, 1 is the main reactor, 11 is the upper feed inlet, 12 is the middle feed inlet, 13 is the lower outlet, 14 is the circulation pump, 2 is the cooler, 3 is the tubular aging reactor, 4 is the devolatilization tower, 41 is the nitrogen inlet, 42 is the tower bottom outlet, and 43 is the tower top outlet. DETAILED DESCRIPTION

[0030] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0031] Example 1

[0032] A method for preparing a narrow distribution polyether polyol comprises the following steps:

[0033] The devices used are Figure 1 As shown, Figure 1 It is a schematic diagram of the structure of the device used in the present invention.

[0034] An upper feed port 11 is provided at the upper part of the main reactor 1, an intermediate feed port 12 is provided at the middle position, and a lower outlet 13 is provided at the bottom. The lower outlet 13 is connected to the bottom of the tubular aging reactor 3 through a pipeline of a circulating pump 14, and another pipeline of the circulating pump 14 is connected to the cooler 2. The pipeline coming out of the cooler 2 enters the main reactor 1 through the upper feed port 11. The main reactor 1, the circulating pump 14, and the cooler 2 form a circulation system. The top of the tubular aging reactor 3 is connected to the upper part of one side of the devolatilization tower 4. The top of the devolatilization tower 4 is provided with a tower top outlet 43, the lower part of the other side of the devolatilization tower 4 is provided with a nitrogen inlet 41, and the bottom of the devolatilization tower 4 is provided with a tower bottom outlet 42.

[0035] The cleaning reaction system is dried, the temperature of the catalyst slurry preparation kettle (model: 5-2000L, purchased from Laizhou Jinda Chemical Machinery Co., Ltd.) is adjusted to <40°C, 560kg glycerol and 1200kg propylene glycol are added, stirring is started, 5kg SnCl2 powder is added, and the catalyst slurry is obtained by stirring evenly, and the inside of the main reactor 1 is entered through the upper feed port 11, and the temperature is adjusted to 70°C, vacuumed for half an hour, replaced with nitrogen three times, and the temperature in the main reactor 1 is raised to 110-115°C. 30kg ethylene oxide (EO) and 270kg propylene oxide (PO) with a mass ratio of 1:9 are mixed in a feed mixer (model: SK type static mixer, purchased from Shanghai Anfit Chemical Equipment Co., Ltd.), and the mixed temperature is about 10°C, and added to the main reactor 1 through a jet mixer. The jet mixer is arranged on the upper part of the intermediate feed port 12, located inside the main reactor 1, immersed in the circulating liquid in the main reactor 1, so that the mixing time is minimized. During the dropwise addition, the pressure in the main reactor 1 is maintained at ≤0.5MPa. After the dropwise addition is completed and the mixture is aged for 1-2 hours, 265kg of ethylene oxide (EO) and 2385kg of propylene oxide (PO) in a mass ratio of 1:9 are continuously added dropwise to the main reactor 1, and the pressure in the main reactor 1 is maintained at ≤0.5MPa. When the dropwise addition amount meets the requirement, the circulation system is turned on for 2-3 hours, and then the switch of the tubular aging reactor 3 is turned on, and the flow rate of the circulation system is adjusted to a flow rate ratio of 40 to the flow rate of the tubular aging reactor 3. In addition, this part of the material is added at a mass ratio of 1:75 of the sum of the masses of glycerol, propylene glycol, and SnCl2 powder to the sum of the masses of ethylene oxide (EO) and propylene oxide (PO) (the sum of the masses of ethylene oxide (EO) and propylene oxide (PO) includes the sum of all the masses of ethylene oxide (EO) and propylene oxide (PO) added in the reaction) to achieve material balance and form a continuous production process. The circulating material enters the main reactor 1 through the ejector. The ejector (not shown in the figure) is located inside the top of the main reactor 1. The ejector is set for two main purposes: one is to provide circulation for the materials in the main reactor 1 and promote the absorption of ethylene oxide (EO) and propylene oxide (PO) in the gas phase into the liquid phase; the other is that the catalyst slurry is transported to the circulation loop upstream of the ejector to ensure that it is fully mixed with the materials in the main reactor 1. A gooseneck (not shown in the figure) and a check valve (not shown in the figure) (model: lift check valve, purchased from Tianjin Exxon Valve Co., Ltd.) are installed in the pipeline coming out of the cooler 2 before entering the main reactor 1 to prevent the reaction mixture from flowing back into the EO / PO feed pipeline during tripping or emergency shutdown. The discharge from the tubular aging reactor 3 passes through the devolatilization tower 4, and the nitrogen entering through the nitrogen inlet 41 is used to blow off trace impurities, and then filtered, and the material is discharged from the bottom outlet 42 of the tower, and the material is cooled to obtain refined narrow distribution polyether polyols, and the tail gas enters the recovery and treatment system from the top outlet 43 of the tower.The analysis showed that the hydroxyl value of the polyether polyol was 410 mKOH / kg, the viscosity was 2990 cp / °C, the moisture content was 0.05%, and the pH was 7.

[0036] The tubular aging reactor 3 is a plug flow reactor, which provides additional residence time for the product of the main reactor 1 to ensure the PO conversion reaction, which is equivalent to the aging process.

[0037] The pressure in the main reactor 1 is controlled by the exhaust valve (model: spring full-open closed safety valve, purchased from Tianjin Exxon Valve Co., Ltd.) and the nitrogen system (installed on the pipeline tee between the exhaust valve and the reactor). The solubility of nitrogen in the raw materials is higher than that in the polyol products, so during normal operation, excess nitrogen needs to be discharged.

[0038] The main reactor 1 is equipped with a heater (self-contained) (the outer jacket of the main reactor, heated by water vapor), which is only used when the device is started up to heat the materials in the main reactor 1 to the temperature required for the reaction. During normal operation, part of the circulating flow passes through the heater, but no heating actually occurs.

[0039] The product of the main reactor 1 enters the tubular aging reactor 3 at a temperature similar to that of the main reactor 1. The reaction of the remaining PO causes the temperature to rise by about 5°C and increases the overall conversion of PO to 99.99%.

[0040] The conversion rate of EO / PO is 99.99%, the theoretical molecular weight of the polyether polyol is 8000, and the actual molecular weight is 7962; the molecular weight distribution index PDI of the polyether polyol is 1.0895, the purity is 99.2%, and the unsaturation is 0.

[0041] Example 2

[0042] A method for preparing a narrow distribution polyether polyol comprises the following steps:

[0043] Clean the reaction system and dry it, adjust the temperature of the catalyst slurry preparation kettle to <40°C, add 560kg glycerol and 1200kg propylene glycol, start stirring, add 5kg SnO powder, stir evenly to obtain catalyst slurry, enter the main reactor through the upper feed port, adjust the temperature to 70°C, vacuum for half an hour, replace with nitrogen three times, and wait for the temperature in the main reactor to rise to 110-115°C. Mix 40kg ethylene oxide (EO) and 360kg propylene oxide (PO) with a mass ratio of 1:9 in the feed mixer, the mixed temperature is about 10°C, and add it to the main reactor through the jet mixer. During the dropping process, the pressure in the main reactor is maintained at ≤0.5MPa. After the dropping is completed and the aging is performed for 1-2 hours, a mixture of 245kg ethylene oxide (EO) and 2205kg propylene oxide (PO) with a mass ratio of 1:9 is continued to be dropped into the main reactor, and the pressure in the main reactor is maintained at ≤0.5MPa. When the dropping amount meets the requirements, the circulation system is turned on for 2-3 hours, and then the tubular aging reactor switch is turned on, and the flow rate of the circulation system is adjusted to 40 with the flow rate ratio of the tubular aging reactor, and this part of the material is added at a mass ratio of 1:75 with the sum of the mass of glycerol, propylene glycol, and SnO powder and the sum of the mass of ethylene oxide (EO) and propylene oxide (PO) (the sum of the mass of ethylene oxide (EO) and propylene oxide (PO) includes the sum of all the mass of ethylene oxide (EO) and propylene oxide (PO) added in the reaction) to achieve material balance and form a continuous production process. The circulating material enters the main reactor through the ejector. The material discharged from the tubular aging reactor passes through the devolatilization tower, and the nitrogen entering the nitrogen inlet blows off the trace impurities, then filters, discharges from the bottom outlet of the tower, cools the material, and obtains refined narrow distribution polyether polyol. The tail gas enters the recovery and treatment system from the top outlet of the tower. The polyether polyol is analyzed to have a hydroxyl value of 420mKOH / kg, a viscosity of 3230cp / ℃, a moisture content of 0.05%, and a pH of 6.9.

[0044] The conversion rate of EO / PO is 99.99%, the theoretical molecular weight of the polyether polyol is 7500, and the actual molecular weight is 7450; the molecular weight distribution index PDI of the polyether polyol is 1.0640, the purity is 99.3%, and the unsaturation is 0.

[0045] Example 3

[0046] A method for preparing a narrow distribution polyether polyol comprises the following steps:

[0047] Clean the reaction system and dry it, adjust the temperature of the catalyst slurry preparation kettle to <40℃, add 560kg glycerol and 1200kg methyl methacrylate, start stirring, add 2.5kg SnO and 2.5SnCl2 powder, stir evenly to obtain catalyst slurry, enter the main reactor through the upper feed port, adjust the temperature to 70℃, vacuum for half an hour, replace with nitrogen three times, and wait for the temperature in the main reactor to rise to 110-115℃. Mix 40kg ethylene oxide (EO) and 360kg propylene oxide (PO) with a mass ratio of 1:9 in the feed mixer, the temperature after mixing is about 10℃, and add it to the main reactor through the jet mixer. During the dropwise addition, the pressure in the main reactor is maintained at ≤0.5MPa. After the dropwise addition is completed and the mixture is aged for 1-2 hours, 245kg of ethylene oxide (EO) and 2205kg of propylene oxide (PO) in a mass ratio of 1:9 are continuously added dropwise to the main reactor, and the pressure in the main reactor is maintained at ≤0.5MPa. When the dropwise addition amount meets the requirements, the circulation system is turned on for 2-3 hours, and then the switch of the tubular aging reactor is turned on, and the flow rate of the circulation system is adjusted to a flow rate ratio of 40 to that of the tubular aging reactor. In addition, this part of the material is added at a mass ratio of 1:60 of the sum of the masses of glycerol, methyl methacrylate, SnO, and SnCl2 powders to the sum of the masses of ethylene oxide (EO) and propylene oxide (PO) (the sum of the masses of ethylene oxide (EO) and propylene oxide (PO) includes the sum of all the masses of ethylene oxide (EO) and propylene oxide (PO) added in the reaction) to achieve material balance and form a continuous production process. The circulating material enters the main reactor through the ejector. The material discharged from the tubular aging reactor passes through the devolatilization tower, and the nitrogen entering the nitrogen inlet blows off the trace impurities, then filters, discharges from the bottom outlet of the tower, cools the material, and obtains refined narrow distribution polyether polyol. The tail gas enters the recovery and treatment system from the top outlet of the tower. The polyether polyol is analyzed to have a hydroxyl value of 446mKOH / kg, a viscosity of 3230cp / ℃, a moisture content of 0.06%, and a pH of 6.8.

[0048] The conversion rate of EO / PO is 99.97%, the theoretical molecular weight of the polyether polyol is 7000, and the actual molecular weight is 6972; the molecular weight distribution index PDI of the polyether polyol is 1.1184, the purity is 99.2%, and the unsaturation is 1.

[0049] Example 4

[0050] A method for preparing a narrow distribution polyether polyol comprises the following steps:

[0051] Clean the reaction system and dry it, adjust the temperature of the catalyst slurry preparation kettle to <40℃, add 376kg diethylene glycol and 810kg propylene glycol, start stirring, add 1.5kg SnO2 and 2.0kg SnCl4 powder, stir evenly to obtain catalyst slurry, enter the main reactor through the upper feed port, adjust the temperature to 70℃, vacuum for half an hour, replace with nitrogen three times, and wait for the temperature in the main reactor to rise to 110-115℃. Mix 27kg ethylene oxide (EO) and 243kg propylene oxide (PO) with a mass ratio of 1:9 in the feed mixer, the mixed temperature is about 10℃, and add it to the main reactor through the jet mixer. During the dropwise addition, the pressure in the main reactor is maintained at ≤0.5MPa. After the dropwise addition is completed and the aging is performed for 1-2 hours, a mixture of 165kg of ethylene oxide (EO) and 1485kg of propylene oxide (PO) in a mass ratio of 1:9 is continuously added dropwise to the main reactor, and the pressure in the main reactor is maintained at ≤0.5MPa. When the dropwise addition amount meets the requirements, the circulation system is turned on for 2-3 hours, and then the switch of the tubular aging reactor is turned on, and the flow rate of the circulation system is adjusted to a flow rate ratio of 40 to that of the tubular aging reactor. In addition, this part of the material is added at a mass ratio of 1:80 of the sum of the masses of diethylene glycol, propylene glycol, SnO2, and SnCl4 to the sum of the masses of ethylene oxide (EO) and propylene oxide (PO) (the sum of the masses of ethylene oxide (EO) and propylene oxide (PO) includes the sum of all the masses of ethylene oxide (EO) and propylene oxide (PO) added in the reaction) to achieve material balance and form a continuous production process. The circulating material enters the main reactor through the ejector. The material discharged from the tubular aging reactor passes through the devolatilization tower, and the nitrogen entering the nitrogen inlet blows off the trace impurities, and then is filtered and discharged from the bottom outlet of the tower. The material is cooled to obtain refined narrow distribution polyether polyol, and the tail gas enters the recovery and treatment system from the top outlet of the tower. The polyether polyol is analyzed to have a hydroxyl value of 470mKOH / kg, a viscosity of 3050cp / ℃, a moisture content of 0.06%, and a pH of 6.8.

[0052] The conversion rate of EO / PO is 99.94%, the theoretical molecular weight of the polyether polyol is 6000, and the actual molecular weight is 5905; the molecular weight distribution index PDI of the polyether polyol is 1.1267, the purity is 99.3%, and the unsaturation is 0.

[0053] Example 5

[0054] A method for preparing a narrow distribution polyether polyol comprises the following steps:

[0055] Clean the reaction system and dry it, adjust the temperature of the catalyst slurry preparation kettle to <40°C, add 350kg methyl acrylate and 820kg propylene glycol, start stirring, add 3.5kg SnCl2 powder and 0.25kg BF3, stir evenly to obtain catalyst slurry, enter the main reactor through the upper feed port, adjust the temperature to 70°C, vacuum for half an hour, replace with nitrogen three times, and wait for the temperature in the main reactor to rise to 110-115°C. Mix 28kg ethylene oxide (EO) and 252kg propylene oxide (PO) with a mass ratio of 1:9 in the feed mixer, the mixed temperature is about 10°C, and add it to the main reactor through the jet mixer. During the dropwise addition, the pressure in the main reactor is maintained at ≤0.5MPa. After the dropwise addition is completed and the aging is performed for 1-2 hours, a mixture of 165kg of ethylene oxide (EO) and 1485kg of propylene oxide (PO) in a mass ratio of 1:9 is continuously added dropwise to the main reactor, and the pressure in the main reactor is maintained at ≤0.5MPa. When the dropwise addition amount meets the requirements, the circulation system is turned on for 2-3 hours, and then the switch of the tubular aging reactor is turned on, and the flow rate of the circulation system is adjusted to a flow rate ratio of 40 to the flow rate of the tubular aging reactor. In addition, this part of the material is added at a mass ratio of 1:75 of the sum of the masses of methyl acrylate, propylene glycol, SnCl2 powder, and BF3 to the sum of the masses of ethylene oxide (EO) and propylene oxide (PO) (the sum of the masses of ethylene oxide (EO) and propylene oxide (PO) includes the sum of all the masses of ethylene oxide (EO) and propylene oxide (PO) added in the reaction) to achieve material balance and form a continuous production process. The circulating material enters the main reactor through the ejector. The material discharged from the tubular aging reactor passes through the devolatilization tower, and the nitrogen entering the nitrogen inlet blows off the trace impurities, then filters, discharges from the bottom outlet of the tower, cools the material, and obtains refined narrow distribution polyether polyol. The tail gas enters the recovery and treatment system from the top outlet of the tower. The polyether polyol is analyzed to have a hydroxyl value of 430mKOH / kg, a viscosity of 2685cp / ℃, a moisture content of 0.07%, and a pH of 6.7.

[0056] The conversion rate of EO / PO is 99.92%, the theoretical molecular weight of the polyether polyol is 7200, and the actual molecular weight is 7115; the molecular weight distribution index PDI of the polyether polyol is 1.1390, the purity is 99.1%, and the unsaturation is 1.

[0057] Example 6

[0058] The ratio of ethylene oxide to propylene oxide in Example 1 was adjusted from 1:9 to 2:3, and other factors remained unchanged. The polyether polyol obtained by analysis had a hydroxyl value of 525 mKOH / kg, a viscosity of 1430 cp / °C, a moisture content of 0.05%, and a pH of 7.1.

[0059] The conversion rate of EO / PO is 99.99%, the theoretical molecular weight of the polyether polyol is 5500, and the actual molecular weight is 5380; the molecular weight distribution index PDI of the polyether polyol is 1.0425, the purity is 99.1%, and the unsaturation is 0.

[0060] Low molecular weight polyether polyols are easy to prepare, but high molecular weight polyether polyols are difficult to prepare.

[0061] Comparative Example 1

[0062] The patent application with publication number CN105111428A discloses a method for preparing a low-odor polyether polyol, which is prepared by reacting an initiator with an olefin oxide under the action of an alkaline catalyst. First, glycerol and an alkaline catalyst are added to a reactor, heated and heated, and vacuumed to remove water. Then, part of the olefin oxide is added to the reactor. In the presence of a catalyst, the glycerol initiator reacts with the olefin oxide at a certain temperature and pressure, and then the remaining olefin oxide is added. The reaction conditions of the olefin oxide added in the front section and the back section are controlled to be different to obtain a polyether polyol. After neutralizing the catalyst and filtering to remove impurities, polyether is obtained. The polyether polyol prepared by the present invention has low odor, stable product quality, and good performance.

[0063] 20 grams of glycerol is used as an initiator, and 4 grams of potassium hydroxide catalyst are added to the reactor, and the temperature is controlled at 120°C to remove water under vacuum for 3 hours. 40 grams of propylene oxide are gradually added to the reactor and allowed to react fully. The reaction temperature is controlled between 90 and 100°C during the reaction process, and the pressure is maintained at 0.02 to 0.1 MPa. Then the remaining 960 grams of ethylene oxide are gradually added to the reactor, the reaction temperature is increased to between 100 and 115°C, and allowed to react fully. After neutralizing the catalyst and filtering to remove impurities, a polyether with an average molecular weight of 5000 is obtained.

[0064] Compared with Comparative Example 2, the present invention adopts a continuous preparation technology, has more practical production value, and has a rigorous process, reliable product analysis data, a narrow product molecular weight distribution, and less by-products, and is more suitable for large-scale production.

[0065] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A method for preparing a narrow distribution polyether polyol, characterized in that: The following steps are involved: Adjust the temperature of the catalyst slurry preparation kettle to <40°C, add the mixed initiator and the main catalyst, or add the mixed initiator, the co-catalyst and the main catalyst, stir evenly to obtain the catalyst slurry, enter the inside of the main reactor, adjust the temperature to 40°C ~ 80°C, evacuate for at least half an hour, replace with nitrogen, wait for the temperature in the main reactor to rise to 15-120°C, continuously add a mixture of ethylene oxide and propylene oxide with a mass ratio of 1:1~15, the temperature of the mixture is 5~15°C, keep the pressure in the main reactor ≤0.5MPa during the dropwise addition, wait for the dropwise addition to be completed, mature for 1~2 hours, continue to drop the mixture of ethylene oxide and propylene oxide with a mass ratio of 1:1~15 into the main reactor, keep the pressure in the main reactor ≤0.5MPa, and when the dropwise addition meets the requirements, start the circulation system circulation 1 to 5 hours, then turn on the switch of the tubular aging reactor, adjust the flow rate of the circulation system to the flow rate of the tubular aging reactor to be 30 to 50, and add this part of the material according to the mass ratio of the sum of the mass of the mixed initiator and the main catalyst to the sum of the mass of ethylene oxide and propylene oxide of 1:50 to 80, or, and add this part of the material according to the mass ratio of the sum of the mass of the mixed initiator, the co-catalyst and the main catalyst to the sum of the mass of ethylene oxide and propylene oxide of 1:50 to 80, the sum of the mass of ethylene oxide and propylene oxide includes the sum of all the masses of ethylene oxide and propylene oxide added in the reaction; so as to achieve material balance and form a continuous production process; the circulating material enters the main reactor, and the discharge from the tubular aging reactor passes through the devolatilization tower, nitrogen blows off trace impurities, and then filters to obtain the narrow distribution polyether polyol; The mass percentage of the main catalyst to the mixed initiator is 0.01 to 1%; The mass percentage of the co-catalyst to the mixed initiator is 0.0001 to 0.8%; The mass of the mixed initiator accounts for 0.5-5% of the sum of the masses of ethylene oxide and propylene oxide, and the sum of the masses of ethylene oxide and propylene oxide includes the sum of all the masses of ethylene oxide and propylene oxide added in the reaction; The main catalyst is selected from at least one of SnCl2, SnCl4, SnO, and SnO2; The co-catalyst is BX3, X is selected from F, Cl, Br, I; The mixed initiator is selected from at least one of glycerol, methyl methacrylate, propylene glycol, sorbitol, sucrose, pentaerythritol, diethylene glycol, propylene glycol, glycerol, monoethanolamine, diethanolamine, triethanolamine, urea and methyl acrylate.

2. The method for preparing a narrow distribution polyether polyol according to claim 1, characterized in that: The mass percentage of the main catalyst to the mixed initiator is 0.28% and 0.3%.

3. The method for preparing a narrow distribution polyether polyol according to claim 1, characterized in that: The mass percentage of the co-catalyst to the mixed initiator is 0.02%.

4. The method for preparing a narrow distribution polyether polyol according to claim 1, characterized in that: The mass of the mixed initiator accounts for 1.3%, 1.66%, 1.25% and 1.33% of the sum of the mass of ethylene oxide and propylene oxide.

5. The method for preparing a narrow distribution polyether polyol according to claim 1, characterized in that: The co-catalyst is BF3.

6. The method for preparing a narrow distribution polyether polyol according to claim 1, characterized in that: The polyether polyol has a hydroxyl value of 350-970 mKOH / kg, a viscosity of 1000-4000 CP / 25° C., a moisture content of ≤0.07%, and a pH of 6.7-7.

1.

7. The method for preparing a narrow distribution polyether polyol according to claim 1, characterized in that: The theoretical molecular weight of the polyether polyol is 1000-8000, and the actual molecular weight is 800-8000.

8. The method for preparing a narrow distribution polyether polyol according to claim 1, characterized in that: The molecular weight distribution index PDI of the polyether polyol is 1 to 1.

2.

9. The method for preparing a narrow distribution polyether polyol according to claim 1, characterized in that: The unsaturation degree of the polyether polyol is 0 or 1.

10. The method for preparing a narrow distribution polyether polyol according to claim 1, characterized in that: The mass ratio of the sum of the mass of the mixed initiator and the main catalyst to the sum of the mass of ethylene oxide and propylene oxide is 1:60, 1:75, 1:80 to add this part of the material; Alternatively, the mass ratio of the sum of the mass of the mixed initiator, the co-catalyst and the main catalyst to the sum of the mass of ethylene oxide and propylene oxide is 1:60, 1:75, 1:80, and this part of the material is added.

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