Method for continuously synthesizing sorbitol-based polyether polyol through sorbitol polyether polyol and microchannel reaction

Abstract

The invention provides a method for continuously synthesizing sorbitol-based polyether polyol through a reaction between sorbitol-based polyether polyol and a microchannel, and the method comprises the following steps: in a microchannel reaction system, carrying out a reaction on raw materials containing a sorbitol-based polyether initiator, sorbitol, a double / multi-metal catalyst and an epoxy compound, the preparation method comprises the following steps: (1) adding the sorbitol-based polyether initiator, the double / multi-metal catalyst and part of the epoxy compound at the initial stage of reaction; (2) adding the sorbitol and part of the epoxy compound in the middle stage of the reaction; and (3) then, continuously adding the rest of epoxy compounds into the reaction. According to the method disclosed by the invention, batch production in each kettle is not needed, the method has the characteristics of high production efficiency, low energy consumption, stable quality control, high economic value and the like, and meanwhile, the sorbitol polyether prepared by the method disclosed by the invention has the characteristics of high molecular weight, narrow distribution, no macromolecular tailing and the like.

Description

Technical Field

[0001] The invention belongs to the field of polyether polyols, and particularly relates to a method for continuously synthesizing sorbitol-based polyether polyols through microchannel reactions and sorbitol polyether polyols. Background Art

[0002] In recent years, with the rapid development of the polyurethane industry, major domestic and foreign manufacturers and scientific research institutions have conducted a lot of research and development work around the improvement of the quality and performance of polyether polyol products and the reduction of production costs. Polyether polyols are mainly prepared by polymerization of ethylene glycol, propylene glycol, glycerol, hexanetriol, pentaerythritol, xylitol, and sucrose with epoxides, while there are few reports on the industrialization of sorbitol polyethers produced with sorbitol as an initiator, and research is generally less.

[0003] Foam plastics prepared with sorbitol polyether as raw material are superior to products based on glycerol polyether, xylitol polyether and sucrose polyether in terms of aging performance, dimensional stability, mechanical properties, softening temperature and oil resistance. They can be used as insulation, sound insulation, moisture-proof and structural materials. In particular, high molecular weight and high functionality sorbitol polyether can effectively improve the fineness of the foam cells, improve the dimensional stability of the foam, and enhance the openness of the foam.

[0004] The general preparation process of sorbitol polyether is: solid sorbitol is used as an initiator, alkali metal is used as a catalyst, and at a certain temperature and pressure, a polymerization reaction is carried out with propylene oxide to generate a sorbitol polyether oligomer, and then the reaction is continued with epoxide to generate a sorbitol polyether intermediate, and finally ethylene oxide is used for end-capping to generate a highly active sorbitol polyether. However, when an alkali metal is used as a catalyst, a chain transfer reaction is easily generated during the polymerization reaction, resulting in a series of defects in the product, such as high viscosity, wide product molecular weight distribution, low relative molecular mass, etc., which affects the product performance indicators and limits the application of the product.

[0005] The general preparation process of narrow distribution sorbitol polyether is: solid sorbitol is used as an initiator and alkali metal is used as a catalyst to polymerize with propylene oxide at a certain temperature and pressure to generate sorbitol polyether oligomers, and then a double metal cyanide complex catalyst is added to continue to react with epoxide to generate narrow distribution sorbitol polyether. Although the sorbitol polyether product generated by this method has a narrow molecular weight distribution, it is necessary to produce sorbitol intermediate polyether by base catalysis in advance, and the process is complicated and has many steps.

[0006] At present, the general preparation process of sorbitol polyether is mainly based on kettle reactor, but this method has the disadvantages of batch production and wide molecular weight distribution. Therefore, it is particularly important to develop a new preparation process for sorbitol polyether, which has high economic value and better energy saving and consumption reduction effect. Summary of the invention

[0007] In order to overcome the problems existing in the prior art, the present invention provides a method for continuously synthesizing low-viscosity sorbitol polyether polyols using microchannel reactions. The method of the present invention does not require batch production in each kettle and does not require base catalysis to produce sorbitol intermediate polyethers. It has the characteristics of high production efficiency, low energy consumption, stable quality control and high economic value. At the same time, the sorbitol polyethers prepared by the preparation method have the characteristics of high molecular weight, narrow distribution, low viscosity and the like.

[0008] According to a first aspect of the present invention, the present invention provides a method for continuously synthesizing sorbitol-based polyether polyols by microchannel reaction, the method comprising: reacting raw materials including a sorbitol-based polyether initiator, sorbitol, a bi / multi-metal catalyst, and an epoxy compound in a microchannel reaction system, wherein;

[0009] (1) adding the sorbitol-based polyether initiator, the bi / multi-metal catalyst and part of the epoxy compound at the initial stage of the reaction;

[0010] (2) adding the sorbitol and part of the epoxy compound in the middle of the reaction;

[0011] (3) Afterwards, the remaining epoxy compound is added to the reaction.

[0012] According to a second aspect of the present invention, the present invention provides a sorbitol-based polyether synthesized by the method of the present invention.

[0013] The method of the present invention does not require batch production for each kettle, and has the characteristics of high production efficiency, low energy consumption, stable quality control and high economic value. At the same time, the sorbitol polyether prepared by the method of the present invention has the characteristics of high molecular weight, narrow distribution, low viscosity, no macromolecular tailing, etc.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) Sorbitol reacts only with the dual / multi-metal catalyst MMC catalyst, avoiding the disadvantages of wide molecular weight distribution and more steps caused by reaction with alkali metals;

[0016] (2) The present invention overcomes the problem that the MMC catalyst cannot directly catalyze the reaction between sorbitol and epoxide;

[0017] (3) This process adopts continuous production throughout the entire process, avoiding the original single-pot batch production;

[0018] (4) The present invention adopts microchannel reaction, the reaction temperature is low, and the reaction can be carried out under relatively high pressure, and the conversion rate of the whole reaction process is high;

[0019] (5) The present invention adopts microchannel reaction. Compared with the original kettle reactor, the molecular weight distribution is narrower and the tailing phenomenon of macromolecules is not very obvious.

[0020] (6) The present invention adopts microchannel reaction, the entire reaction is safe, and the device requires less floor space at the same output. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a process flow chart of continuously synthesizing sorbitol-based polyether polyols through a microchannel reaction according to one embodiment of the present invention. DETAILED DESCRIPTION

[0022] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0023] It should also be noted that the various specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0024] In addition, the various embodiments of the present invention may be arbitrarily combined as long as they do not violate the concept of the present invention. The technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0025] The present invention provides a method for continuously synthesizing sorbitol-based polyether polyols by microchannel reaction, the method comprising: reacting raw materials including a sorbitol-based polyether initiator, sorbitol, a bi / multi-metal catalyst (MMC), and an epoxy compound in a microchannel reaction system, wherein;

[0026] (1) adding the sorbitol-based polyether initiator, the bi / multi-metal catalyst and part of the epoxy compound at the initial stage of the reaction;

[0027] (2) adding the sorbitol and part of the epoxy compound in the middle of the reaction;

[0028] (3) After that, the remaining epoxy compound is added to the reaction. The present invention adopts a microchannel reaction, the reaction temperature is low, and the reaction can be carried out under a relatively high pressure, and the conversion rate of the whole reaction process is high; compared with the original kettle reactor, the molecular weight distribution is narrower, the macromolecular tailing phenomenon is not very obvious, the whole reaction is safe, and the area required for the device is also less at the same output.

[0029] In the present invention, there is no special requirement for the operating parameters of the microchannel reaction, and commonly used microchannel reactors and operating parameters can be used in the present invention. The following is an exemplary description, but the scope of the present invention is not limited thereby.

[0030] Specifically, in the present invention, the system pressure of the microchannel reaction system is 0.5-2MPa, for example, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1MPa, 1.2MPa, 1.4MPa, 1.6MPa, 1.8MPa, and 2MPa.

[0031] Specifically, for example, the diameter of the pipeline of the microchannel reaction system is 1-5 mm.

[0032] Specifically, for example, the volume range of the microchannel reaction system is 5-50 ml.

[0033] According to a preferred embodiment of the present invention, the remaining epoxy compound is further added to the reaction in one or more stages.

[0034] In the present invention, there is no special requirement for the selection of the sorbitol-based polyether initiator, and the initiators commonly used in the art can be used in the present invention. According to a preferred embodiment of the present invention, the molecular weight of the sorbitol-based polyether initiator is 300 g / mol to 1500 g / mol, preferably 600 to 1200 g / mol.

[0035] In the present invention, in a preferred embodiment, the sorbitol-based polyether initiator is obtained by the reaction of sorbitol, an alkali metal catalyst and an epoxy compound, or is an intermediate polyether II prepared in part of step (2).

[0036] In this way, sorbitol reacts with the alkali metal catalyst and the dual / multi-metal catalyst respectively, thus avoiding the disadvantage of wide molecular weight distribution caused by reacting only with the alkali metal catalyst.

[0037] In the present invention, the alkali metal catalyst has a wide range of optional types, and the present invention has no special requirements for this. In a preferred embodiment, the alkali metal catalyst is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0038] According to a preferred embodiment of the present invention, the sorbitol is liquid sorbitol.

[0039] In the present invention, the optional range of the types of the epoxy compound is relatively wide. The following exemplary description is given, but the scope of the present invention is not limited thereto. The epoxy compound is selected from C2 to C10 epoxy compounds, preferably C2 to C6 epoxy compounds, and more preferably at least one of ethylene oxide, propylene oxide, butylene oxide, and cyclohexene oxide. A mixture of ethylene oxide and propylene oxide may also be used.

[0040] In the present invention, preferably, the double / multi-metal catalyst is a double metal cyanide catalyst (DMC) and / or a multi-metal cyanide (MMC) catalyst. Wherein, the double metal cyanide catalyst (DMC) and the multi-metal cyanide catalyst (MMC) disclosed in the prior art can be used, and the present invention introduces the definition of the double metal cyanide catalyst (DMC) and the multi-metal cyanide catalyst (MMC) in the prior art into the present invention. For example, the double metal cyanide catalyst (DMC) / multi-metal cyanide catalyst (MMC) disclosed in CN101302286A, CN110684187A, CN113881032A, CN1500554A, CN1566183A, etc.

[0041] In the present invention, the operating conditions in step (1), step (2), and step (3) can be selected in a wide range, which is described below for exemplary purposes, but does not limit the scope of the present invention.

[0042] According to a preferred embodiment of the present invention, based on 100 wt% of the weight of the sorbitol-based polyether initiator, the amount of the bi / multi-metal catalyst is 0.003 wt% to 2 wt%, preferably 0.06 wt% to 1 wt%.

[0043] According to a preferred embodiment of the present invention, step (1) is carried out at 100-150°C, preferably 110-130°C.

[0044] According to a preferred embodiment of the present invention, in step (1), the mass ratio of the sorbitol-based polyether initiator to the epoxy compound is 1:1-10.

[0045] According to a preferred embodiment of the present invention, in step (1), the molecular weight of the synthesized intermediate polyether I is 600 g / mol to 5000 g / mol, preferably 1000 to 4000 g / mol, and more preferably 2400 to 3600 g / mol.

[0046] According to a preferred embodiment of the present invention, step (2) is carried out at 100-150°C, preferably 110-140°C.

[0047] According to a preferred embodiment of the present invention, in step (2), the mass ratio of the intermediate polyether I synthesized in step (1), sorbitol and the epoxy compound is 1:0.1-5:1-10;

[0048] According to a preferred embodiment of the present invention, in step (2), the molecular weight of the synthesized intermediate polyether II is 600 g / mol to 15000 g / mol, preferably 1000 to 4000 g / mol, and more preferably 1350 to 2100 g / mol.

[0049] According to a preferred embodiment of the present invention, step (3) is carried out at 100-150°C, preferably 110-130°C.

[0050] According to a preferred embodiment of the present invention, in step (3), the mass ratio of the intermediate polyether II synthesized in step (2) to the epoxy compound is 1:2-15.

[0051] The present invention has no special requirements on the structure of the microchannel reaction system. The following is an exemplary description, but the scope of the present invention is not limited thereby.

[0052] According to a preferred embodiment of the present invention, the microchannel reaction system comprises:

[0053] More than two micro-reaction units, each micro-reaction unit includes a raw material storage tank such as an epoxy compound storage tank and / or a dual / multi-metal catalyst storage tank and / or a sorbitol-based polyether initiator storage tank; a metering pump, a micro-reactor, a back pressure valve, and a pressure gauge. Each of the micro-reactors has a plurality of micro-channels according to the reaction requirements, and a suitable number of feed ports and discharge ports according to the feeding requirements.

[0054] According to a preferred embodiment of the present invention, the microchannel reaction system comprises at least three micro-reaction units; a sorbitol-based polyether initiator, a bi / multi-metal catalyst and a portion of an epoxy compound are added to the first micro-reaction unit I to carry out the initial reaction described in step (1);

[0055] Add the sorbitol and part of the epoxy compound into the second micro-reaction unit II to carry out the intermediate stage of the reaction described in step (2);

[0056] The remaining epoxy compound is then added to the subsequent micro-reaction unit to carry out step (3).

[0057] According to a preferred embodiment of the present invention, the method comprises:

[0058] (1) mixing a sorbitol-based polyether initiator, a bimetallic / multimetallic catalyst and an epoxy compound in a first micro-reaction unit I to carry out a first-stage reaction to obtain an intermediate polyether I;

[0059] (2) mixing the intermediate polyether I, sorbitol and the epoxy compound in a second micro-reaction unit II to carry out a two-stage reaction to obtain an intermediate polyether II;

[0060] (3) Part or all of the intermediate polyether II and the epoxy compound are mixed in the third micro-reaction unit III to carry out a three-stage reaction, and the sorbitol-based polyether polyol is obtained after aging and degassing.

[0061] According to a preferred embodiment of the present invention, the sorbitol-based polyether initiator is stored after being prepared in step (2). In this way, sorbitol reacts only with the bi / multi-metal catalyst, thus avoiding the disadvantages of wide molecular weight distribution and multiple reaction steps caused by the reaction with an alkali metal catalyst.

[0062] In the present invention, the first-stage reaction, the second-stage reaction and the third-stage reaction are independently continuous feeding and continuous discharging to achieve the continuous preparation.

[0063] In a preferred embodiment of the present invention, the sorbitol-based polyether initiator is obtained as follows: sorbitol, an alkali metal catalyst, and an epoxy compound are mixed for a first-stage reaction, and the sorbitol-based polyether initiator is obtained by degassing and post-treatment.

[0064] In the present invention, in a further preferred embodiment, when preparing the sorbitol-based polyether initiator, sorbitol and an alkali metal catalyst are first mixed, heated to 110 to 150° C. (e.g., 110° C., 120° C., 130° C., 140° C. or 150° C.) under a protective atmosphere for dehydration, and then cooled to 80 to 130° C. (80° C., 90° C., 100° C., 110° C., 120° C. or 130° C.) to carry out the first stage reaction.

[0065] In the present invention, in a further preferred embodiment, the protective atmosphere is selected from at least one of nitrogen and an inert gas, such as nitrogen.

[0066] In the present invention, in a preferred embodiment, when preparing the sorbitol-based polyether initiator, the amount of the alkali metal catalyst is 2wt% to 30wt%, preferably 3wt% to 20wt%, for example, 3wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt% or 20wt%, based on 100wt% of the weight of the sorbitol.

[0067] In the present invention, in a preferred embodiment, the molecular weight of the sorbitol-based polyether initiator is 300 g / mol to 1500 g / mol, preferably 600 to 1200 g / mol, for example 300 g / mol, 500 g / mol, 800 g / mol, 1000 g / mol, 1200 g / mol or 1500 g / mol.

[0068] In a preferred embodiment of the present invention, when preparing the sorbitol-based polyether initiator, the degassing refers to removing the unreacted epoxy compound.

[0069] In the present invention, in a preferred embodiment, when preparing the sorbitol-based polyether initiator, the post-treatment sequentially includes emulsification, neutralization, adsorption, dehydration and filtration.

[0070] In the present invention, in a further preferred embodiment, when preparing the sorbitol-based polyether initiator, the post-treatment includes: emulsification by adding water, neutralization to a pH of 4.5-6, addition of an adsorbent for adsorption, dehydration, and filtration.

[0071] In the present invention, in a further preferred embodiment, oxalic acid and / or phosphoric acid are used for neutralization, and / or the adsorbent is selected from at least one of magnesium silicate, aluminum silicate, and magnesium aluminum silicate.

[0072] According to a preferred embodiment of the present invention, in step (1), a bi / multi-metal catalyst is first added to the sorbitol-based polyether initiator to form a sorbitol-based polyether initiator containing a bi / multi-metal catalyst, and the initiator is heated and dehydrated, and then mixed with an epoxy compound to carry out the first-stage reaction.

[0073] According to a preferred embodiment of the present invention, preferably, in step (1), the feed is divided into two routes, wherein one route is the sorbitol-based polyether initiator added with a dual / multi-metal catalyst, and the other route is the epoxy compound; preferably, in step (1), the feed is divided into two routes (in a dropwise manner) into the reactor I, wherein one route is the sorbitol-based polyether initiator added with a dual / multi-metal catalyst, and the other route is the epoxy compound.

[0074] According to a preferred embodiment of the present invention, preferably, in step (1), the temperature-raising dehydration is carried out at 100-140°C, preferably 110-130°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C.

[0075] According to a preferred embodiment of the present invention, in step (1), based on 100wt% of the weight of the sorbitol-based polyether initiator, the amount of the bi / multi-metal catalyst is 0.003wt% to 2wt%, preferably 0.006wt% to 1wt%, for example, 0.003wt%, 0.005wt%, 0.008wt%, 0.01wt%, 0.02wt%, 0.05wt%, 0.08wt%, 0.1wt%, 0.2wt%, 0.4wt%, 0.6wt%, 0.8wt%, 1wt%, 1.1wt%, 1.3wt%, 1.4wt%, 1.5wt%, etc.

[0076] According to a preferred embodiment of the present invention, in step (1), the first stage reaction is carried out at 100-150°C, preferably 110-130°C, for example 100°C, 110°C, 120°C, 130°C, 140°C, 150°C.

[0077] According to a preferred embodiment of the present invention, in step (1), the molecular weight of the intermediate polyether I is 600 g / mol to 5000 g / mol, preferably 1000 to 4000 g / mol, and more preferably 2400 to 3600 g / mol. For example, 600 g / mol, 800 g / mol, 1000 g / mol, 1200 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2200 g / mol, 2500 g / mol, 2800 g / mol, 3000 g / mol, 3500 g / mol, 4000 g / mol, 4500 g / mol, and 5000 g / mol.

[0078] According to a preferred embodiment of the present invention, in step (2), the second stage reaction is carried out at 100-150°C, preferably 110-140°C, for example 100°C, 110°C, 120°C, 130°C, 140°C, 150°C.

[0079] According to a preferred embodiment of the present invention, in step (2), the intermediate polyether I, sorbitol and epoxy compound are added dropwise into the micro-reaction unit II in three separate routes.

[0080] In the step (2), a certain amount of sorbitol is added to avoid the batch production of a large amount of sorbitol intermediate I using a relatively high alkali metal catalyst in the step (1).

[0081] According to a preferred embodiment of the present invention, in step (2), based on 100wt% of the weight of the intermediate polyether I, the amount of sorbitol is 0.01wt% to 200wt%, preferably 0.1wt% to 100wt%, for example, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 10%, 20%, 50%, 80%, 100%, 120%, 150%, 180% or 200%.

[0082] According to a preferred embodiment of the present invention, the mass ratio of the intermediate polyether I, sorbitol and epoxy compound is 1:0.1-5:1-10.

[0083] According to a preferred embodiment of the present invention, in step (2), the molecular weight of the intermediate polyether II is 600 g / mol to 15000 g / mol, preferably 1000 to 4000 g / mol, more preferably 1350 to 2100 g / mol, for example 600 g / mol, 1000 g / mol, 1500 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol, 4000 g / mol, 4500 g / mol, 5000 g / mol, 5500 g / mol, 6000 g / mol, 8000 g / mol, 1000 g / mol, 12000 g / mol, 14000 g / mol, 15000 g / mol.

[0084] According to a preferred embodiment of the present invention, in step (3), part or all of the intermediate polyether II and the epoxy compound are added dropwise into the micro-reaction unit III in two ways.

[0085] According to a preferred embodiment of the present invention, in step (3), the molecular weight of the sorbitol polyether polyol is 2000 g / mol to 15000 g / mol, preferably 6000 to 13000 g / mol; for example, 2000 g / mol, 3000 g / mol, 4000 g / mol, 5000 g / mol, 6000 g / mol, 7000 g / mol, 8000 g / mol, 9000 g / mol, 10000 g / mol, 11000 g / mol, 12000 g / mol, 13000 g / mol, 14000 g / mol or 15000 g / mol.

[0086] According to a preferred embodiment of the present invention, in step (3), the three-stage reaction is carried out at 100-150°C, preferably 110-130°C, for example 100°C, 110°C, 120°C, 130°C, 140°C, 150°C.

[0087] According to a preferred embodiment of the present invention, the mass ratio of the intermediate polyether II to the epoxy compound is 1:2-15.

[0088] In the present invention, the function of step (3) is to perform aging and degassing. Aging is to further react the unreacted epoxide, and degassing is to remove the unreacted epoxide in vacuum after aging.

[0089] According to a preferred embodiment of the present invention, when only part of the intermediate polyether II enters step (3), the remaining intermediate polyether II replaces the initiator or is stored for next use.

[0090] According to a preferred embodiment of the present invention, in step (3), preferably, 70-100wt% (preferably excluding 100wt%, for example, 70wt%, 75wt%, 80wt%, 85wt%, 90wt% or 95wt%) of the intermediate polyether II enters step (3), and the remaining intermediate polyether II goes to step (1) to replace the sorbitol-based polyether initiator therein (for example, after mixing with the MMC catalyst, it returns to step (1), and the concentration refers to the concentration range of step (1), which can be adjusted as needed). In a further preferred embodiment, when 75-95wt% of the intermediate polyether II enters the three-stage reaction of step (3), the remaining intermediate polyether II goes to step (1) to replace the sorbitol-based polyether initiator therein.

[0091] In this way, except for the use of a small amount of the above-mentioned alkali metal-catalyzed sorbitol polyether initiator in the initial reaction stage, part of the intermediate polyether II is recycled back to step (1) in the subsequent continuous reaction process to replace the above-mentioned sorbitol polyether initiator, thereby simplifying the production steps of the original continuous production process of sorbitol polyether. In the subsequent production process, sorbitol can be directly used to produce sorbitol polyether without the need to synthesize the intermediate first.

[0092] The invention provides sorbitol-based polyether synthesized by the method of the invention.

[0093] In the present invention, each micro-reaction unit reaction independently and continuously feeds and discharges materials to achieve the continuous preparation.

[0094] In the present invention, in step (1), the material in the first micro-reaction unit I enters the second micro-reaction unit II, and then the material in the second micro-reaction unit II enters the third micro-reaction unit III, avoiding the original single-pot MMC (multi-metal catalyst) intermittent production.

[0095] In the present invention, there is no special requirement for the way in which each raw material is added, and generally, continuous dropwise addition is adopted.

[0096] In a preferred embodiment, when only part of the intermediate polyether II enters the three-stage reaction of step (3), the remaining intermediate polyether II goes to step (1) or is stored for use next time. Thus, the production steps of the original continuous production process of sorbitol polyether are simplified, and the production process of sorbitol polyether is basically realized by directly using sorbitol without synthesizing the intermediate first.

[0097] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0098] The raw materials used in the examples and comparative examples, if not specifically limited, are all disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation method disclosed in the prior art. The MMC catalyst in the examples and comparative examples is prepared by Example 1 in CN101302286A. In the examples and comparative examples, the molecular weight during the reaction is theoretically estimated, and the number average molecular weight and molecular weight distribution index of the final product are obtained by GPC detection.

[0099] In the present invention, the sorbitol-based polyether initiator is obtained by adding 500g of sorbitol and 8g of potassium hydroxide into a 2L stainless steel kettle, replacing with nitrogen, measuring the oxygen content in the kettle to be less than 150ppm, stirring and heating to 120°C, dehydrating, cooling to 110°C, starting to add 1150g of propylene oxide, dropping the internal pressure to a stable pressure, and discharging to obtain a crude sorbitol intermediate ether. The crude intermediate ether obtained above is added into 85g of pure water, stirred and emulsified, and heated to 90°C, and then 27g of 50% phosphoric acid is added for neutralization reaction after 1 hour, and then 6g of magnesium aluminum silicate is added for adsorption after 1 hour, and then dehydrating and filtering to obtain a sorbitol-based polyether initiator with a molecular weight of 600.

[0100] In the present invention, the MMC catalyst in the examples and comparative examples is prepared by Example 1 in CN101302286A, and its composition is: Co 8.1% (weight), Zn 22.4% (weight), Fe 0.5% (weight), tert-butyl alcohol 15.4% (weight), dimethyl phthalate 22.0% (weight).

[0101] The following examples adopt Figure 1 The microchannel reaction system shown performs:

[0102] The microchannel reaction system of the following embodiment contains three reaction units. The parameters of the three microreactors are as follows: the inner diameter of the reactor pipe is 1 mm, the reaction volume is 30 mL, and the first microreactor, the second microreactor, and the third microreactor are connected in series along the material flow direction.

[0103] Wherein, the first microreactor is fed with sorbitol-based polyether initiator, MMC catalyst, and epoxide;

[0104] Wherein, the second microreactor is fed with sorbitol-based polyether initiator and epoxide;

[0105] Wherein, the third microreactor is fed with epoxide;

[0106] According to needs, the discharge port of each microreactor is connected to the feed port of the previous microreactor for material recycling.

[0107] Figure 1 This is a schematic diagram, which only shows the feed relationship. The specific feed can be mixed or unmixed with various raw materials.

[0108] For example, the feed in the first micro-reaction unit I is generally added dropwise continuously in two ways, one way is the sorbitol-based polyether initiator mixed with MMC, and the other way is the epoxide.

[0109] For example, in the second micro-reaction unit II, three continuous dripping paths are used, one path is the intermediate polyether I, one path is sorbitol, and the last path is PO.

[0110] For example, in the third micro-reaction unit III, two continuous dripping paths are used, one path is the intermediate polyether II, and the other path is PO.

[0111] In the present invention, the molecular weight refers to the weight average molecular weight.

[0112] In the present invention, viscosity determination: using Brookfield DV2+PRO type rotational viscometer to test the viscosity of the polyether sample at 25±1.5°C;

[0113] Molecular weight determination: Waters 1515, column temperature 35°C, mobile phase tetrahydrofuran, flow rate 1 ml / min. Polystyrene was used as standard.

[0114] [Example 1]

[0115] Add 500g of sorbitol-based polyether initiator to the pretreatment kettle, then add 2.7g of MMC catalyst, and stir to mix. Add in two ways in the first micro-reaction unit I, one way is the sorbitol-based polyether initiator mixed with MMC (based on the weight of the sorbitol-based polyether initiator 100wt%, the amount of MMC is 0.54wt%), and the other way is PO, the mass ratio of the two is 1:3, the reaction temperature is 120°C, until the material in the first micro-reaction unit I enters the second micro-reaction unit II. At this time, the first micro-reaction unit I is the intermediate polyether I with a molecular weight of 2400. In the second micro-reaction unit II, three paths are added dropwise, one path is the intermediate polyether I, one path is sorbitol, and the last path is PO, the mass ratio of the three is 1:1:5.6, and the reaction temperature is 120°C, until part (93.34wt%) of the second micro-reaction unit II overflows to the third micro-reaction unit III, and part (6.67wt%) returns to the first micro-reaction unit I to replace the aforementioned sorbitol-based polyether initiator. At this time, the second micro-reaction unit II is the intermediate polyether II, with a molecular weight of 1350. A certain amount of catalyst (2gMMC / 500g) is added to the intermediate polyether II returned to the micro-reaction unit I in proportion, and after stirring, it is dripped into the micro-reaction unit I in two paths with PO. In the third micro-reaction unit III, two paths are added dropwise, one path is the intermediate polyether II, and the other path is PO, the mass ratio of the two is 1:7.89, the reaction temperature is 120°C, the outlet pressure of the entire system is controlled to be 0.8MPa by the back pressure valve, and the material flows from the third micro-reaction unit III to the finished product tank. At this time, the finished product tank is the sorbitol polyether polyol finished product 1, and the properties are shown in Table 1.

[0116] [Example 2]

[0117] Add 500g of sorbitol-based polyether initiator to the pretreatment kettle, then add 1.8g of MMC catalyst, and stir to mix. Add in two ways in the first micro-reaction unit I, one way is the sorbitol-based polyether initiator mixed with MMC (based on the weight of the sorbitol-based polyether initiator 100wt%, the amount of MMC is 0.36wt%), and the other way is PO, the mass ratio of the two is 1:5, the reaction temperature is 115°C, until the material in the first micro-reaction unit I enters the second micro-reaction unit II. At this time, the first micro-reaction unit I is the intermediate polyether I with a molecular weight of 3600. In the second micro-reaction unit II, three drops are added, one is the intermediate polyether I, one is sorbitol, and the last is PO / EO (molar ratio is 7:1), the mass ratio of the three is 2:1:9, the reaction temperature is 125°C, until part (90.9wt%) of the second micro-reaction unit II overflows to the third micro-reaction unit III, and part (9.1wt%) returns to the first micro-reaction unit I to replace the aforementioned sorbitol-based polyether initiator. At this time, the second micro-reaction unit II is the intermediate polyether II, with a molecular weight of 2100. A certain amount of catalyst (1.5gMMC / 500g) is added to the intermediate polyether II returned to the first micro-reaction unit I in proportion, and after stirring, it is dripped into the first micro-reaction unit I in two drops with PO. In the third micro-reaction unit III, two drops are added, one is the intermediate polyether II, and the other is PO / EO (molar ratio is 7:1), the mass ratio of the two is 1:4.75, the reaction temperature is 115°C, the outlet pressure of the whole system is controlled by the back pressure valve to be 1.0MPa, and the material flows from the third micro-reaction unit III to the finished product tank. At this time, the finished product tank is the sorbitol polyether polyol finished product 2, and the properties are shown in Table 1.

[0118] [Example 3]

[0119] Add 500g of sorbitol-based polyether initiator to the pretreatment kettle, then add 2.5g of MMC catalyst, and stir to mix. Add in two ways in the first micro-reaction unit I, one way is the sorbitol-based polyether initiator mixed with MMC (based on the weight of the sorbitol-based polyether initiator 100wt%, the amount of MMC is 0.5wt%), and the other way is PO, the mass ratio of the two is 1:3, the reaction temperature is 110°C, until the material in the first micro-reaction unit I enters the second micro-reaction unit II. At this time, the first micro-reaction unit I is the intermediate polyether I with a molecular weight of 2400. In the second micro-reaction unit II, three paths are added dropwise, one path is the intermediate polyether I, one path is sorbitol, and the last path is PO, the mass ratio of the three is 1:1:9, and the reaction temperature is 130°C, until part (93.02wt%) of the second micro-reaction unit II overflows to the third micro-reaction unit III, and part (6.98wt%) returns to the first micro-reaction unit I to replace the aforementioned sorbitol-based polyether initiator. At this time, the second micro-reaction unit II is the intermediate polyether II, with a molecular weight of 1850. A certain amount of catalyst (1.8gMMC / 500g) is added to the intermediate polyether II returned to the micro-reaction unit I in proportion, and after stirring, it is dripped into the first micro-reaction unit I in two paths with PO. In the third micro-reaction unit III, two paths are added dropwise, one path is the intermediate polyether II, and the other path is PO, the mass ratio of the two is 1:5.5, the reaction temperature is 110°C, and the outlet pressure of the entire system is controlled to be 1.2MPa by the back pressure valve, and the material flows from the third micro-reaction unit III to the finished product tank. At this time, the finished product tank is the sorbitol polyether polyol finished product 3, and the properties are shown in Table 1.

[0120] [Example 4]

[0121] The method of Example 1 is different from that of Example 1:

[0122] Add 500g of sorbitol-based polyether initiator to the pretreatment kettle, then add 3.2g of MMC catalyst, and stir to mix. Add in two ways in the first micro-reaction unit I, one way is the sorbitol-based polyether initiator mixed with MMC (based on the weight of the sorbitol-based polyether initiator 100wt%, the amount of MMC is 0.64wt%), and the other way is PO, the mass ratio of the two is 1:3, the reaction temperature is 125°C, until the material in the first micro-reaction unit I enters the second micro-reaction unit II. At this time, the first micro-reaction unit I is the intermediate polyether I with a molecular weight of 2400. In the second micro-reaction unit II, three drops are added, one is the intermediate polyether I, one is sorbitol, and the last is PO, the mass ratio of the three is 1:1:5.6, and the reaction temperature is 135°C, until part (93.34wt%) of the second micro-reaction unit II overflows to the third micro-reaction unit III, and part (6.67wt%) returns to the first micro-reaction unit I to replace the aforementioned sorbitol-based polyether initiator. At this time, the second micro-reaction unit II is the intermediate polyether II, with a molecular weight of 1350. A certain amount of catalyst (2.5gMMC / 500g) is added to the intermediate polyether II returned to the micro-reaction unit I in proportion, and after stirring, it is dripped into the micro-reaction unit I in two ways with PO. In the third micro-reaction unit III, two drops are added, one is the intermediate polyether II, and the other is PO, the mass ratio of the two is 1:7.89, the reaction temperature is 125°C, the outlet pressure of the entire system is controlled to be 1.4MPa by the back pressure valve, and the material flows from the third micro-reaction unit III to the finished product tank. At this time, the finished product tank is the sorbitol polyether polyol finished product 4, and the properties are shown in Table 1.

[0123] [Example 5]

[0124] The method of Example 1 is different from that of Example 1:

[0125] Add 500g of sorbitol-based polyether initiator into the pretreatment kettle, then add 3.7g of MMC catalyst, stir and mix (based on the weight of the sorbitol-based polyether initiator 100wt%, the amount of MMC is 0.74wt%). Add dropwise in two ways in the first micro-reaction unit I, one way is the sorbitol-based polyether initiator mixed with MMC, and the other way is PO, the mass ratio of the two is 1:5, the reaction temperature is 130°C, until the material in the first micro-reaction unit I enters the second micro-reaction unit II. At this time, the first micro-reaction unit I is the intermediate polyether I with a molecular weight of 3600. In the second micro-reaction unit II, three drops are added, one is the intermediate polyether I, one is sorbitol, and the last is PO / EO (molar ratio is 7:1), the mass ratio of the three is 2:1:9, the reaction temperature is 140°C, until part (90.9wt%) of the second micro-reaction unit II overflows to the third micro-reaction unit III, and part (9.1wt%) returns to the first micro-reaction unit I to replace the aforementioned sorbitol-based polyether initiator. At this time, the second micro-reaction unit II is the intermediate polyether II, with a molecular weight of 2100. A certain amount of catalyst (3.4gMMC / 500g) is added to the intermediate polyether II returned to the first micro-reaction unit I according to proportion, and after stirring, it is dripped into the first micro-reaction unit I in two ways with PO. In the third micro-reaction unit III, two drops are added, one is the intermediate polyether II, and the other is PO / EO (molar ratio is 7:1), the mass ratio of the two is 1:4.75, the reaction temperature is 130°C, the outlet pressure of the whole system is controlled by the back pressure valve to be 1.6MPa, and the material flows from the third micro-reaction unit III to the finished product tank. At this time, the finished product tank is the sorbitol polyether polyol finished product 2, and the properties are shown in Table 1.

[0126] [Comparative Example 1]

[0127] 100g of unrefined sorbitol polyether initiator (base catalysis) was added to the reactor, and after nitrogen replacement, stirring and heating to 140°C, 1900g of propylene oxide was continued to be added dropwise, and the pressure was controlled within 0.4MPa. After the internal pressure was stabilized after the dropping, the sorbitol finished crude ether was obtained by degassing and discharging. 100g of the finished crude ether obtained above was added to pure water, stirred and emulsified, and heated to 90°C. After 1 hour, 27g of 50% phosphoric acid was added for neutralization reaction, and 6g of magnesium aluminum silicate was added for adsorption after 1 hour, and then dehydrated and filtered to obtain sorbitol finished refined ether polyol 6, and the properties are shown in Table 1.

[0128] This method is currently commonly used in production equipment. First, it is intermittent production, which leads to disadvantages such as low production efficiency, high energy consumption, and unstable quality control of each batch. Secondly, it is base catalysis, which leads to disadvantages such as wide molecular weight distribution and high viscosity.

[0129] The method of the present invention has the characteristics of high production efficiency, low energy consumption, stable quality control and high economic value. At the same time, the sorbitol polyether obtained by the preparation method has the characteristics of high molecular weight, narrow distribution and low viscosity.

[0130] (1) Sorbitol reacts only with the dual / multi-metal catalyst MMC catalyst, avoiding the disadvantages of wide molecular weight distribution and more steps caused by reaction with alkali metals;

[0131] (2) The present invention overcomes the problem that the MMC catalyst cannot directly catalyze the reaction between sorbitol and epoxide.

[0132] Comparative Example 2

[0133] According to the method of Example 1, the difference is that no microchannel reaction system is used, and three reactors are used to carry out the first, second and third stage reactions. The specific steps are as follows:

[0134] Add 500g of sorbitol-based polyether initiator to the autoclave reactor I, then add 2.7g of MMC catalyst, stir to mix, and add dropwise in two ways, one way is sorbitol-based polyether initiator mixed with MMC (based on the weight of the sorbitol-based polyether initiator 100wt%, the amount of MMC is 0.54wt%), and the other way is PO, the mass ratio of the two is 1:3, the reaction temperature is 135°C, until the autoclave reactor I is full and overflows to the autoclave reactor II. At this time, the autoclave reactor I is the intermediate polyether I with a molecular weight of 2400. Add dropwise in the autoclave reactor II in three ways, one way is the intermediate polyether I, one way is sorbitol, and the last way is PO, the mass ratio of the three is 1:1:5.6, the reaction temperature is 140°C, until part (93.34wt%) of the autoclave reactor II overflows to the autoclave reactor III, and part (6.67wt%) returns to the autoclave reactor I to replace the aforementioned sorbitol-based polyether initiator. At this time, the kettle reactor II is the intermediate polyether II, with a molecular weight of 1350. A certain amount of catalyst (2gMMC / 500g) is added to the intermediate polyether II returned to the kettle reactor I in proportion, and after stirring, it is dripped into the kettle reactor I in two ways with PO. In the kettle reactor III, two ways are dripped, one is the intermediate polyether II, and the other is PO. The mass ratio of the two is 1:7.89, and the reaction temperature is 140°C. After the kettle is full, the material flows from the kettle reactor III to the finished product tank. At this time, the finished product tank is the sorbitol polyether polyol finished product 7, and the properties are shown in Table 1.

[0135] Comparative Example 3

[0136] Add 500g of sorbitol-based polyether initiator to the pre-treatment kettle, then add 2.7g of MMC catalyst, and stir to mix. In the first micro-reaction unit I, add dropwise in two ways, one way is the sorbitol-based polyether initiator mixed with MMC (based on the weight of the sorbitol-based polyether initiator 100wt%, the amount of MMC is 0.54wt%), and the other way is PO, the mass ratio of the two is 1:3, the reaction temperature is 120°C, until the material in the first micro-reaction unit I enters the second micro-reaction unit II. At this time, the first micro-reaction unit I is the intermediate polyether I, with a molecular weight of 2400. In the second micro-reaction unit II, add dropwise in three ways, one way is the intermediate polyether I, one way is sorbitol, and the last way is PO, the mass ratio of the three is 1:1:68.9, the reaction temperature is 120°C, the outlet pressure of the entire system is controlled to be 0.8MPa by the back pressure valve, and the material flows from the second micro-reaction unit II to the finished product tank. At this time, the finished product tank is the sorbitol polyether polyol finished product 8, and the properties are shown in Table 1.

[0137] Table 1

[0138]

[0139] As can be seen from Table 1 above, the sorbitol polyether polyol finished products 1 / 2 / 3 / 4 / 5 have the advantages of low viscosity and the narrowest molecular weight distribution, and no need for prior base catalysis to synthesize the sorbitol polyether initiator. The first advantage of the polyether 6 in Comparative Example 1 is that it is produced by an intermittent method, which leads to disadvantages such as low production efficiency, high energy consumption, and unstable quality control of each batch. The second disadvantage is that it is base catalyzed, which leads to disadvantages such as wide molecular weight distribution and high viscosity. The polyether 7 in Comparative Example 2 uses a kettle reactor, so the reaction temperature is relatively high to obtain the same product. The polyether 7 in Comparative Example 3 is fed all at once in the second micro-reaction unit II without segmented reaction, resulting in a slightly wide molecular weight distribution and high viscosity.

[0140] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for continuously synthesizing sorbitol-based polyether polyols by microchannel reaction, characterized in that: The method comprises: reacting raw materials including a sorbitol-based polyether initiator, sorbitol, a bi / multi-metal catalyst, and an epoxy compound in a microchannel reaction system, wherein; (1) adding the sorbitol-based polyether initiator, the bi / multi-metal catalyst and part of the epoxy compound at the initial stage of the reaction; (2) adding the sorbitol and part of the epoxy compound in the middle of the reaction; (3) Afterwards, the remaining epoxy compound is added to the reaction.

2. The method according to claim 1, wherein: The operating parameters of the microchannel reaction system include: The system pressure is 0.5-2MPa; and / or The diameter of the pipeline of the microchannel reaction system is 1-5 mm; and / or The volume range of the microchannel reaction system is 5-50 ml; and / or The remaining epoxy compound is then added to the reaction in one or more stages; and / or The molecular weight of the sorbitol-based polyether initiator is 300 g / mol to 1500 g / mol, preferably 600 to 1200 g / mol; and / or The sorbitol is liquid sorbitol; and / or The epoxy compound is selected from C2-C10 epoxy compounds, preferably C2-C6 epoxy compounds, and more preferably at least one selected from ethylene oxide, propylene oxide, butylene oxide, and cyclohexene oxide; and / or The double / multi-metal catalyst is a double metal cyanide catalyst (DMC) and / or a multi-metal cyanide (MMC) catalyst; and / or The conditions in step (1) include: Based on 100 wt% of the weight of the sorbitol-based polyether initiator, the amount of the bi / multi-metal catalyst is 0.003 wt% to 2 wt%, preferably 0.06 wt% to 1 wt%; and / or The mass ratio of the sorbitol-based polyether initiator to the epoxy compound is 1:1-10; and / or At 100-150°C, preferably 110-130°C; The molecular weight of the synthesized intermediate polyether I is 600 g / mol to 5000 g / mol, preferably 1000 to 4000 g / mol, more preferably 2400 to 3600 g / mol; and / or, The conditions in step (2) include: At 100-150°C, preferably 110-140°C; The mass ratio of the intermediate polyether I synthesized in step (1), sorbitol and epoxy compound is 1:0.1-5:1-10; The molecular weight of the synthesized intermediate polyether II is 600 g / mol to 15000 g / mol, preferably 1000 to 4000 g / mol, more preferably 1350 to 2100 g / mol; and / or The conditions in step (3) include: At 100-150°C, preferably 110-130°C; The mass ratio of the intermediate polyether II synthesized in step (2) to the epoxy compound is 1:2-15.

3. The method according to claim 1 or 2, wherein: The microchannel reaction system comprises: more than two microreaction units, each microreaction unit comprises a raw material storage tank, a metering pump, a microreactor, a back pressure valve, and a pressure gauge, and each microreactor has a plurality of microchannels as required.

4. The method according to any one of claims 1 to 3, wherein: The microchannel reaction system includes at least 3 micro-reaction units; Adding a sorbitol-based polyether initiator, a bimetallic / multimetallic catalyst and a portion of an epoxy compound to the first micro-reaction unit I to carry out the initial reaction described in step (1); Adding the sorbitol and part of the epoxy compound into the second micro-reaction unit II to carry out the intermediate stage of the reaction described in step (2); The remaining epoxy compound is then added to the subsequent micro-reaction unit to carry out step (3).

5. The method according to any one of claims 1 to 4, wherein: The method includes: (1) mixing a sorbitol-based polyether initiator, a bimetallic / multimetallic catalyst and an epoxy compound in a first micro-reaction unit I to carry out a first-stage reaction to obtain an intermediate polyether I; (2) mixing the intermediate polyether I, sorbitol and the epoxy compound in a second micro-reaction unit II to carry out a two-stage reaction to obtain an intermediate polyether II; (3) Part or all of the intermediate polyether II and the epoxy compound are mixed in the third micro-reaction unit III to carry out a three-stage reaction, and the sorbitol-based polyether polyol is obtained after aging and degassing.

6. The method according to any one of claims 1 to 5, wherein: In step (1), Feed in two ways, one of which is the sorbitol-based polyether initiator with a double / multi-metal catalyst, and the other is the epoxy compound; Based on 100 wt% of the weight of the sorbitol-based polyether initiator, the amount of the bi / multi-metal catalyst is 0.003 wt% to 2 wt%, preferably 0.06 wt% to 1 wt%; and / or The mass ratio of the sorbitol-based polyether initiator to the epoxy compound is 1:1-10; and / or The first stage reaction is carried out at 100-150°C, preferably 110-130°C; and / or, The molecular weight of the intermediate polyether I is 600 g / mol to 5000 g / mol, preferably 1000 to 4000 g / mol, and more preferably 2400 to 3600 g / mol.

7. The method according to claim 5 or 6, wherein: In step (2), The second stage reaction is carried out at 100-150°C, preferably 110-140°C; and / or The intermediate polyether I, sorbitol and epoxy compound are added dropwise into the micro-reaction unit II in three ways; and / or The mass ratio of the intermediate polyether I, sorbitol and epoxy compound is 1:0.1-5:1-10; The molecular weight of the intermediate polyether II is 600 g / mol to 15000 g / mol, preferably 1000 to 4000 g / mol, and more preferably 1350 to 2100 g / mol.

8. The method according to any one of claims 5 to 7, wherein: In step (3), Part or all of the intermediate polyether II and epoxy compound are added dropwise into the micro-reaction unit III in two ways; and / or, The mass ratio of the intermediate polyether II to the epoxy compound is 1:2-15; The molecular weight of the sorbitol polyether polyol is 2000 g / mol to 15000 g / mol, preferably 6000 to 13000 g / mol; and / or, The three-stage reaction is carried out at 100-150°C, preferably 110-130°C.

9. The method according to any one of claims 5 to 8, wherein: When only part of the intermediate polyether II enters step (3), the remaining intermediate polyether II replaces the initiator or is stored for use next time; Preferably, 70-100 wt % of the intermediate polyether II enters step (3), and the rest of the intermediate polyether II goes to step (1) to replace the sorbitol-based polyether initiator therein.

10. The sorbitol-based polyether synthesized by the method according to any one of claims 1 to 9.

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