Preparation method of low-odor polyether

Abstract

The invention belongs to the technical field of polyether synthesis, and discloses a preparation method of low-odor polyether. The preparation method comprises the following steps: adding an alcohol initiator and a catalyst into a reaction kettle, heating, and adding epoxide for reaction to prepare a polyether crude product; adding the polyether crude product into a post-treatment kettle, adding acid and an adsorbent for treatment, and filtering to obtain refined polyether; and adding the refined polyether and steam without air into a deodorizing kettle at the same time, and performing deodorizing treatment to obtain the low-odor polyether. The odor of the polyether can be effectively reduced, the content of formaldehyde is lower than 0.1 ppm, the content of acetaldehyde is lower than 0.3 ppm, the content of propionaldehyde is lower than 1.0 ppm, the content of acrolein is lower than 0.05 ppm, the content of acetone is lower than 0.5 ppm, and the odor grade is 1; and the preparation method is simple, and the odor removal time can be greatly shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of polyether synthesis, and particularly relates to a method for preparing low-odor polyether. Background Art

[0002] In recent years, with the continuous improvement of environmental protection concepts, how to effectively improve the increasingly complex in-car quality links and provide consumers with a healthy driving environment has become a problem that all automobile companies urgently need to solve. Therefore, customers are paying more and more attention to the odor of polyether. In the synthesis technology of polyether polyols, efforts should be made to improve product quality and meet environmental protection needs. At present, more car seat cushions use high-resilience PU foam. In recent years, the automobile industry has developed rapidly, coupled with the rapid development of civil aviation and high-speed rail, the development and production of high-resilience PU foam seat cushions that are both comfortable and safe is urgent.

[0003] Major domestic and foreign manufacturers and scientific research institutions have also done a lot of work on the odor problem of polyether polyol products. For example, a technology discloses a refining system and refining method for low-odor polyether, which is prepared by combining a bubbling bed reactor with a ceramic membrane separator, adding a hydrogenation catalyst to the ceramic membrane separator, and introducing hydrogen to react to prepare low-odor polyether. However, the equipment required for this method is complex, the loaded catalyst is difficult to prepare and expensive, and the hydrogenation reaction needs to be carried out under ultra-high pressure and high temperature. There is also a technology that uses a composition including a cation exchange resin and an adsorbent to treat polyether polyols to obtain high-quality polyether polyols with a total amount of Na and K less than 5ppm and an aldehyde content less than 5ppm, wherein the cation exchange resin needs to be treated with a strong acid for resurrection and utilization, generating a large amount of wastewater. There is also a technology that purifies polymer polyols by using stripping of a packed tower, but for polymer polyols, pop particles or residual monomers are very likely to scale on the inner surface of the tower or even block the pipeline under heating conditions, thereby affecting the heat transfer efficiency and removal effect, and increasing the difficulty of operating and handling equipment. There is also a technique in which peroxide is added to a polyether polyol through a feed line extending into the bottom of the kettle in a closed reactor, mixed at a certain pressure and temperature, and then the mixture is post-processed to obtain a polyether polyol product with a low VOC content. However, peroxide has strong oxidizing properties and is easy to oxidize the hydroxyl groups of the original polyether to aldehyde groups or ketones, which causes the product to deteriorate. There is also a technique that discloses a method for preparing a high-solid content, low-VOC polymer polyol, wherein the product is passed through a multi-stage thin film evaporator and a multi-stage removal tank, and an inert gas is introduced under a high vacuum state to remove vaporized vinyl monomers, solvents and other small molecules. There is also a technique that adds an aldehyde scavenger to a base polyether polyol, and reacts the aldehyde scavenger with one or more aldehyde compounds to remove one or more aldehyde compounds, thereby preparing a low-odor polyether polyol. However, the product after the hydrazine compound aldehyde scavenger added in this method reacts with the aldehyde is not easy to remove and remains in the product, and the excess aldehyde scavenger needs to be added with isocyanate to react to form another by-product, which ultimately increases the by-products of the product and reduces the purity of the product. There is also a technology that uses nitrogen bubbling and medium-pressure steam bubbling through a bottom distribution tube to remove moisture and aldehyde compounds from polyether polyols, and sets the pressure to -0.075 to -0.085 MPa to prepare low-odor polyether polyols. This method consumes a large amount of nitrogen, and the steam and logistics are not in sufficient contact, so it takes longer to remove low-odor substances such as aldehydes and ketones.

[0004] Therefore, there is an urgent need to provide an efficient and simple method for preparing low-odor polyethers, which can shorten the time of the deodorization step and significantly reduce the content of small molecular aldehydes and ketones. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a method for preparing a low-odor polyether. The method provided by the present invention can shorten the time of the deodorization step and prepare a polyether with low content of formaldehyde, acetaldehyde, acrolein and acetone.

[0006] The invention provides a method for preparing low-odor polyether.

[0007] Specifically, a method for preparing a low-odor polyether is prepared using a preparation system for the low-odor polyether, comprising the following steps:

[0008] (1) adding an alcohol initiator and a catalyst into a reaction kettle, raising the temperature, and adding an epoxide to react to obtain a crude polyether;

[0009] (2) adding the crude polyether prepared in step (1) into a post-treatment kettle, adding acid and / or adsorbent for treatment, and filtering to obtain a refined polyether;

[0010] (3) adding the refined polyether prepared in step (2) and steam without air into a deodorizing kettle at the same time, and performing deodorizing treatment at 75 to 130° C. and a vacuum degree of −0.070 to −0.095 MPa; finally, stopping the introduction of the steam, and performing vacuum dehydration to obtain a low-odor polyether;

[0011] The preparation system comprises:

[0012] A reactor for preparing a crude polyether product, the reactor comprising a material feed pipe and a crude polyether product discharge pipe;

[0013] A post-processing kettle, wherein the feed port of the post-processing kettle is connected to the crude polyether discharge pipe, and the post-processing kettle comprises a refined polyether discharge pipe;

[0014] A deodorizing kettle, wherein the feed port of the deodorizing kettle is connected to the refined polyether discharge pipe, the deodorizing kettle comprises a mixer, an atomizer and a finished product discharge port, the mixer is directly connected to the atomizer, and the finished product discharge port is arranged at the bottom of the deodorizing kettle;

[0015] A steam generator, the steam generator comprising a steam outlet pipe and a first water inlet pipe, the steam outlet pipe and the refined polyether discharge pipe are both connected to the mixer on the deodorizing kettle;

[0016] A water storage device, the water storage device comprises a second water inlet pipe, a vacuum pipe, a nitrogen inlet pipe and a gas distributor; the gas distributor is located inside the water storage device and is connected to the nitrogen inlet pipe for dispersing nitrogen.

[0017] Preferably, the alcohol initiator in step (1) is at least one selected from allyl alcohol, methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and trimethylolpropane.

[0018] Preferably, the catalyst in step (1) comprises at least one of potassium hydroxide, sodium hydroxide, sodium methoxide, potassium methoxide or metallic sodium; the amount of the catalyst used is 1‰ to 5‰ of the total mass of the initiator alcohol and the epoxide.

[0019] Preferably, before heating in step (1), vacuuming, nitrogen filling to replace air, and dehydration or low-boiling treatment are performed.

[0020] Preferably, the temperature of the dehydrated or low-boiling substances is 80-120°C.

[0021] Preferably, the epoxide in step (1) is at least one of propylene oxide, ethylene oxide and butylene oxide. Preferably, the mass ratio of propylene oxide to butylene oxide and ethylene oxide is 1:0-2:0-2.

[0022] Preferably, the reaction temperature in step (1) is 80-130°C.

[0023] Preferably, before adding the crude polyether product to the post-treatment kettle in step (2), the post-treatment kettle is first evacuated and filled with nitrogen to replace the air.

[0024] Preferably, the adsorbent in step (2) is magnesium silicate, magnesium aluminum silicate or modified high-efficiency magnesium silicate adsorbent. If modified high-efficiency magnesium silicate adsorbent is used, post-treatment does not require acid neutralization, and only requires water and adsorption dehydration by the adsorbent.

[0025] Preferably, the amount of the adsorbent used in step (2) is 2‰ to 20‰ of the total mass of the alcohol initiator and the epoxide.

[0026] Preferably, the temperature for treatment with the adsorbent in step (2) is 60 to 80° C. and the time is 10 to 60 minutes.

[0027] Preferably, before adding the refined polyether into the deodorizing kettle in step (3), the deodorizing kettle is first subjected to a treatment of evacuating the air and filling it with nitrogen to replace the air.

[0028] Preferably, in step (3), the deodorization treatment is carried out at 80 to 130° C. and a vacuum degree of -0.070 to -0.095 MPa for 1 to 5 hours.

[0029] Preferably, the vacuum dehydration in step (3) is performed to a moisture content of ≤0.2%, wherein the vacuum degree is greater than or equal to -0.095 MPa.

[0030] Preferably, the molecular weight of the low-odor polyether prepared in step (3) is 300 to 8000.

[0031] Preferably, in the preparation system, the reactor further comprises a heat exchange device for controlling the temperature of the reactor.

[0032] Preferably, in the preparation system, a filtering device is further provided on the refined polyether discharge pipe of the post-treatment kettle for removing solids in the refined polyether, such as catalysts, adsorbents, etc.

[0033] Preferably, in the preparation system, a first external circulation pipe is further provided on the refined polyether discharge pipe of the post-treatment kettle, and the first external circulation pipe is connected to the top of the post-treatment kettle. When the polyether post-treatment does not meet the requirements, it is re-transported to the post-treatment kettle through the first external circulation pipe for treatment.

[0034] Preferably, in the preparation system, the atomizer is provided with a plurality of atomizing nozzles.

[0035] Preferably, in the preparation system, when the steam outlet pipe and the second external circulation pipe are connected to the mixer on the deodorizing kettle, the pipe openings of the steam outlet pipe and the second external circulation pipe are both beveled openings, and the beveled openings of the two are arranged oppositely. The steam entering through the oppositely arranged beveled openings and the preheated refined polyether merge in the mixer, and can be more fully mixed and contacted, which is conducive to the subsequent steam to better carry away the aldehyde and ketone odor substances.

[0036] Preferably, in the preparation system, the bevel opening includes a bevel plate and holes arranged on the bevel plate, the diameter of the holes is 0.5-1.5 mm, and the number of the holes is 35-100 / cm 2 .

[0037] Preferably, in the preparation system, the gas distributor is located at the bottom of the water storage device. The nitrogen dispersed by the gas distributor enters the water from the bottom of the water storage device and can fully contact the water. The vacuum effect of the vacuum tube can more thoroughly remove the air dissolved in the water, so that the water entering the steam generator later does not contain air, thereby avoiding air mixed in the steam, and oxidizing the polyether to form by-product aldehydes and ketones with odor substances when entering the deodorization kettle.

[0038] Preferably, in the preparation system, the gas distributor is an annular gas distributor; the annular gas distributor is a circular tube provided with a plurality of small holes, the diameter of the small holes is 0.5 to 1.5 mm, and the distribution amount of the small holes is 25 to 50 per m.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The method for preparing low-odor polyether provided by the present invention adopts a low-odor polyether preparation system for preparation, firstly prepares a crude polyether, and then after post-treatment, uses air-free steam in combination with vacuum extraction to remove small molecular aldehydes, ketones, etc. in the polyether. By controlling the temperature and vacuum degree during the deodorization process, the odor of the polyether can be effectively reduced.

[0041] (2) The preparation method provided by the invention can be used to prepare low-odor polyether, wherein the formaldehyde content is less than 0.1 ppm, the acetaldehyde content is less than 0.3 ppm, the propionaldehyde content is less than 1.0 ppm, the acrolein content is less than 0.05 ppm, and the acetone content is less than 0.5 ppm, and the odor level is 1; and the preparation method is simple and can greatly shorten the deodorization time. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram of a system for preparing a low-odor polyether provided by an embodiment of the present invention;

[0043] Figure 2 for Figure 1 A magnified cross-section of area A in the middle;

[0044] Description of Figure Numbers:

[0045] 100-reaction kettle, 110-material feed pipe, 120-polyether crude product discharge pipe, 130-heat exchange device;

[0046] 200-post-treatment kettle, 210-refined polyether discharge pipe, 220-filtering device, 230-first external circulation pipe;

[0047] 300-deodorizing kettle, 310-mixer, 320-atomizer, 321-atomizing nozzle, 330-finished product outlet, second external circulation pipe-340;

[0048] 400-steam generator, 410-steam outlet pipe, 420-first water inlet pipe;

[0049] 500 - water storage device, 510 - gas distributor, 520 - second water inlet pipe, 530 - vacuum pipe, 540 - nitrogen inlet pipe. DETAILED DESCRIPTION

[0050] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following examples are listed for illustration. It should be noted that the following examples do not limit the scope of protection claimed in the present invention. The raw materials, reagents or devices used in the following examples and comparative examples can be obtained from conventional commercial channels or can be obtained by existing known methods unless otherwise specified.

[0051] The method for preparing the low-odor polyether provided in the embodiment of the present invention adopts a preparation system for the low-odor polyether, and the preparation system comprises:

[0052] Reactor 100, reactor 100 is used to prepare polyether crude product, which includes a material feed pipe 110 and a polyether crude product discharge pipe 120; it can be understood that the material feed pipe 110 is connected to the feed port of the reactor 100, and the polyether crude product discharge pipe 120 is connected to the discharge port at the bottom of the reactor 100. Alcohol initiator, catalyst and epoxide enter the reactor 100 through the material feed pipe 110, and the solid catalyst can be directly put into the reactor 100. In some embodiments of the present invention, the reactor 100 also includes a heat exchange device 130, which is used in conjunction with an external circulation pipe and a circulation pump to control the temperature of the reactor 100, realize heating and cooling of the reaction materials, etc. Further, the reactor 100 is also provided with a conventional inert gas (such as nitrogen) inlet pipe, a vacuum tube, a pressure gauge, a thermometer, etc., and a material stirring device can also be provided inside the reactor 100.

[0053] The post-processing kettle 200, the feed port of the post-processing kettle 200 is connected to the polyether crude product discharge pipe 120, and the post-processing kettle 200 includes a refined polyether discharge pipe 210, which is connected to the discharge port of the post-processing kettle 200. Further, a filtering device 220 is also provided on the refined polyether discharge pipe 210 of the post-processing kettle 200, which is used to remove solids in the refined polyether, such as catalysts, adsorbents, etc. One or more circulating pumps can be installed or set on the refined polyether discharge pipe 210 as needed. In some embodiments of the present invention, a first external circulation pipe 230 is also provided on the refined polyether discharge pipe 210 of the post-processing kettle 200, and the first external circulation pipe 230 is connected to the top of the post-processing kettle 200. In the initial stage of treatment by the filtering device, the quality of the discharged polyether is unstable, and when the post-processing of the polyether does not meet the requirements, it is re-transported to the post-processing kettle 200 through the first external circulation pipe 230 for treatment. In addition, the post-processing kettle 200 can also be provided with a conventional inert gas (such as nitrogen) inlet pipe, a vacuum tube, a pressure gauge, a thermometer, etc. according to actual needs, and a material stirring device is also provided inside the post-processing kettle 200.

[0054] Deodorizing kettle 300, the feed port of deodorizing kettle 300 is connected to refined polyether discharge pipe 210, deodorizing kettle 300 includes mixer 310, atomizer 320, second external circulation pipe 340 and finished product discharge port 330, mixer 310 is directly connected to atomizer 320, finished product discharge port 330 is arranged at the bottom of deodorizing kettle 300, one end of second external circulation pipe 340 is connected to the finished product discharge port 330, and the other end is connected to the top of deodorizing kettle 300. Steam generator 400, steam generator 400 includes steam outlet pipe 410 and first water inlet pipe 420, steam outlet pipe 410 and second external circulation pipe 340 are both connected to mixer 310 on deodorizing kettle 300. Further, as Figure 2 As shown, the steam outlet pipe 410 and the second external circulation pipe 340 are both beveled, and the bevels of the two are arranged opposite to each other. The beveled opening includes a beveled plate and holes arranged on the beveled plate, wherein the diameter of the holes is 0.5 to 1.5 mm, and the number of holes is 35 to 100 per cm 2 . Steam and the preheated refined polyether enter the mixer through the holes of the beveled mouth. The steam that enters through the relatively arranged beveled mouths at the same time and the preheated refined polyether merge in the mixer 310, and can be more fully mixed and contacted, which is conducive to the subsequent steam to better carry away aldehyde and ketone odorous substances. Specifically, the polyether treated in the post-treatment kettle 200 enters the deodorization kettle 300 through the refined polyether discharge pipe 210. After preheating, the polyether material enters the mixer 310 from the second external circulation pipe 340 and the steam input through the steam outlet pipe 410 at the same time, and is atomized by the connected atomizer 320 and re-enters the deodorization kettle 300 for deodorization treatment. In some embodiments of the present invention, such as Figure 2 As shown, the atomizer 320 is provided with a plurality of atomizing nozzles 321, and the spacing between the atomizing nozzles 321 is 5 to 30 cm, such as 20 cm. It should be understood that the deodorizing kettle 300 can also be provided with a conventional inert gas (such as nitrogen) inlet pipe, vacuum tube, pressure gauge, thermometer, etc. according to actual needs.

[0055] The water storage device 500 includes a second water inlet pipe 520, a vacuum tube 530, a nitrogen inlet pipe 540 and a gas distributor 510; the gas distributor 510 is located inside the water storage device 500 and is connected to the nitrogen inlet pipe 540 for dispersing nitrogen. Further, the gas distributor 510 is located at the bottom of the water storage device 500. The nitrogen dispersed by the gas distributor 510 enters the water from the bottom of the water storage device 500 and can fully contact with the water (generally deionized water is used). By utilizing the vacuum effect of the vacuum tube 530, the air dissolved in the water can be more thoroughly taken away, so that the water subsequently entering the steam generator 400 does not contain air, thereby avoiding the steam prepared by the steam generator 400 from being mixed with air, and preventing the oxidized polyether from forming by-product aldehydes and ketones with odor substances when entering the deodorizing kettle 300. In some embodiments of the present invention, the gas distributor 510 is an annular gas distributor; the annular gas distributor is a circular tube provided with a plurality of small holes, the diameter of the small holes is 0.5-1.5 mm, and the distribution amount of the small holes is 25-50 / m.

[0056] Preparation of the reactor before implementation: first wash the preparation system several times with distilled water until it is clean, dry the reactor, and cool it to room temperature for use. The content of aldehydes and ketones mentioned in the examples and comparative examples is determined by high performance liquid chromatography; the odor evaluation method is tested according to the polyether polyol odor test standard VDA270. The evaluation criteria are shown in Table 1.

[0057] Table 1

[0058]

[0059] Example 1

[0060] A method for preparing a low-odor polyether comprises the following steps:

[0061] 500kg of allyl alcohol and 10kg of potassium methoxide catalyst were put into the reactor, and the air in the reactor was replaced by N2 after vacuuming. After replacement twice, the temperature was raised to 80°C and a mixture of 762kg of ethylene oxide and 3048kg of propylene oxide was continuously added. The reaction temperature was controlled at 100°C. After the addition, the temperature was kept at 120°C and the reaction was continued for 2 hours. After the reaction, low boiling points were removed by vacuuming, and the temperature was lowered to 60°C and discharged to obtain a crude polyether.

[0062] The crude polyether is transferred into a post-treatment kettle, and 260 kg of deionized water and 18 kg of phosphoric acid (85% content) are added for neutralization. After adding 22 kg of magnesium silicate adsorbent, the kettle is evacuated to ≥-0.09 MPa, and N2 is charged to the pressure in the kettle to 0.02 MPa. After vacuuming to ≥-0.09 MPa, N2 is charged to the pressure in the kettle to 0.02 MPa. This is repeated three times. The temperature is raised to 70°C and stirred for adsorption for 30 minutes. The temperature is then raised while vacuuming for dehydration. The temperature is raised to 120°C. The vacuum degree is ≥-0.098 MPa and maintained for 1.5 hours. The vacuum is then turned off, the temperature is lowered to 60°C, and the air in the container is replaced by repeated vacuuming and N2 charging.

[0063] Deionized water is input into the water storage device. After the water storage device is evacuated to ≥-0.096MPa, N2 is filled into the water storage device from the gas distributor at the bottom of the device until the pressure inside the device is 0.02MPa. After evacuating the water storage device again, N2 is filled into the water storage device to a pressure of 0.2-0.35MPa for standby use. After the steam generator and the steam outlet pipe connected to the deodorization kettle are evacuated to ≥-0.098MPa, N2 is filled to a pressure of 0.02MPa in the container. After evacuating the water storage device to ≥-0.096MPa, N2 is filled to a pressure of 0.02MPa in the kettle. After repeating this process 3 times, the pressure inside the device is evacuated to a pressure of 0.2-0.35MPa for standby use. Use; after the deodorization kettle is evacuated to ≥-0.098MPa, N2 is filled in until the pressure inside the kettle is 0.02MPa, and then the pressure is evacuated to ≥-0.098MPa, and N2 is filled in until the pressure inside the kettle is 0.02MPa. After repeating this process 3 times, the refined polyether after post-treatment is transferred into the deodorization kettle, and the external circulation is started while evacuating and heating up to 80°C (preheating). The valves of the steam generator and the second external circulation pipe on the deodorization kettle are opened to allow steam to continuously enter the mixer in the deodorization kettle, and after mixing with the preheated refined polyether in the mixer, the steam is sprayed into the deodorization kettle by the atomizing nozzle of the atomizer. Control the opening of the steam valve to make the vacuum degree in the deodorization kettle at -0.080 ~ -0.090MPa and the material temperature at 90 ~ 100 ℃ for the deodorization process. After maintaining for 1.5 hours, close the valve between the steam generator and the deodorization kettle, continue to vacuum dehydration, control the dehydration temperature at about 100 ℃, until the moisture content of the material is ≤0.2%, then cool it to below 60 ℃ to discharge the material to obtain low-odor polyether.

[0064] Example 2

[0065] A method for preparing a low-odor polyether comprises the following steps:

[0066] 500kg of glycerol and 16kg of KOH catalyst were put into the reactor. After vacuuming, the air in the reactor was replaced with N2. After two replacements, the reactor was vacuumed to ≥-0.098MPa and heated to 120℃ for dehydration for 1h. After dehydration, a mixture of 2467kg of ethylene oxide and 2467kg of propylene oxide was continuously added. The reaction temperature was controlled at 100℃. After the addition, the reaction was continued at 1200℃ for 2 hours. After the reaction, low-boiling substances were removed by vacuum, and the temperature was lowered to 60℃ to discharge the material to obtain a crude polyether.

[0067] The crude polyether was transferred into a post-treatment kettle, and 330 kg of deionized water and 56 kg of modified high-efficiency adsorbent (POLYSORB 30 / 40 from Dallas Company) were added. The kettle was evacuated to ≥-0.09 MPa, and then N2 was added to the kettle pressure to 0.02 MPa. The kettle was evacuated to ≥-0.09 MPa, and then N2 was added to the kettle pressure to 0.02 MPa. This process was repeated three times. The temperature was raised to 70°C, and adsorbed with stirring for 30 minutes. The vacuum was then applied for dehydration while the temperature was raised. The temperature was raised to 120°C, and the vacuum degree was maintained at ≥-0.098 MPa for 1.5 hours. The vacuum was then turned off, the temperature was lowered to 60°C, and the kettle was filtered and transferred into a deodorization kettle in which the air in the container was replaced by repeated vacuuming and N2 filling.

[0068] Deionized water is input into the water storage device. After the water storage device is evacuated to ≥-0.096MPa, N2 is filled into the water storage device from the gas distributor at the bottom of the water storage device until the pressure in the device is 0.02MPa. After evacuating the water storage device again, N2 is filled into the water storage device to a pressure of 0.2-0.35MPa for standby use. After the steam generator and the steam outlet pipe connected to the deodorization kettle are evacuated to ≥-0.098MPa, N2 is filled to a pressure of 0.02MPa in the kettle. After evacuating the water storage device to ≥-0.096MPa, N2 is filled to a pressure of 0.02MPa in the kettle. After evacuating the water storage device again to ≥-0.098MPa, N2 is filled to a pressure of 0.02MPa in the kettle. After repeating this process 3 times, the pressure in the kettle is 0.2-0.35MPa for standby use. Use; after the deodorization kettle is evacuated to ≥-0.098MPa, N2 is filled in until the pressure inside the kettle is 0.02MPa, and then the pressure is evacuated to ≥-0.098MPa, and N2 is filled in until the pressure inside the kettle is 0.02MPa. After repeating this process 3 times, the refined polyether after post-treatment is transferred into the deodorization kettle, and the external circulation is started while evacuating and heating up to 80°C (preheating). The valves of the steam generator and the second external circulation pipe on the deodorization kettle are opened to allow steam to continuously enter the mixer in the deodorization kettle, and after mixing with the preheated refined polyether in the mixer, the steam is sprayed into the deodorization kettle by the atomizing nozzle of the atomizer. Control the opening of the steam valve to make the vacuum degree in the deodorization kettle between -0.085 and -0.095 MPa and the material temperature between 100 and 120°C for the deodorization process. After maintaining for 1.5 hours, close the valve between the steam generator and the deodorization kettle, continue to vacuum dehydration, control the dehydration temperature at 100°C, until the moisture content of the material is ≤0.2%, then cool it to below 60°C to discharge the material to obtain low-odor polyether.

[0069] Embodiments 3 to 6

[0070] Example 3 According to the process conditions of Example 1, the types and amounts of the starting material, catalyst, epoxide, adsorbent, phosphoric acid and water were adjusted; Examples 4 to 6 were according to the process conditions of Example 2, the types and amounts of the raw materials, catalyst, epoxide, adsorbent and water were adjusted; the results are shown in Table 2.

[0071] Table 2 Examples 3 to 6

[0072]

[0073] Comparative Example 1

[0074] A method for preparing a low-odor polyether comprises the following steps:

[0075] 500 kg of allyl alcohol and 10 kg of potassium methoxide catalyst were put into the reactor, and the air in the reactor was replaced with N2 after vacuuming. After two replacements, the temperature was raised to 80°C and a mixture of 762 kg of ethylene oxide and 3048 kg of propylene oxide was continuously added. The reaction temperature was controlled at 100°C, and the temperature was kept at 120°C for 2 hours. After the reaction, low boiling points were removed by vacuuming, and the temperature was lowered to 60°C to discharge the material to obtain a crude polyether.

[0076] The crude polyether is transferred to a post-treatment kettle, and 260 kg of deionized water and 18 kg of phosphoric acid (85% content) are added for neutralization. After adding 22 kg of magnesium silicate adsorbent, the kettle is evacuated to ≥-0.09 MPa, and N2 is charged to a pressure of 0.02 MPa in the kettle. After vacuuming to ≥-0.09 MPa, N2 is charged to a pressure of 0.02 MPa in the kettle. This is repeated three times. The temperature is raised to 70°C, and stirred for adsorption for 30 minutes. The temperature is raised while vacuuming for dehydration. The temperature is raised to 120, and the vacuum degree is ≥-0.098 MPa. After maintaining for 1.5 hours, the vacuum is turned off, the temperature is lowered to 60°C, and filtered to obtain the finished polyether product.

[0077] Comparative Example 2

[0078] A method for preparing a low-odor polyether comprises the following steps:

[0079] 500kg of glycerol and 16kg of KOH catalyst were put into the reactor. After vacuuming, the air in the reactor was replaced with N2. After two replacements, the reactor was vacuumed to ≥-0.098MPa and heated to 110℃ for dehydration for 1h. After dehydration, a mixture of 2467kg of ethylene oxide and 2467kg of propylene oxide was continuously added. The reaction temperature was controlled at 100℃. After addition, the reaction was continued at 120℃ for 2 hours. After the reaction, low-boiling substances were removed by vacuum, and the temperature was lowered to 60℃ for discharge to obtain a crude polyether.

[0080] The crude polyether was transferred into a post-treatment kettle, and 330 kg of deionized water and 56 kg of modified high-efficiency adsorbent were added. The kettle was evacuated to ≥-0.09 MPa, and then N2 was introduced to increase the pressure in the kettle to 0.02 MPa. The kettle was evacuated to ≥-0.09 MPa, and then N2 was introduced to increase the pressure in the kettle to 0.02 MPa. This process was repeated three times. The temperature was raised to 70 °C, and the mixture was stirred and adsorbed for 30 min. The temperature was raised while the vacuum was applied for dehydration. The temperature was raised to 120 °C, and the vacuum degree was maintained at ≥-0.098 MPa for 1.5 h. The vacuum was then turned off, the temperature was lowered to 60 °C, and the polyether product was obtained by filtration.

[0081] Comparative Examples 3 to 6

[0082] Comparative Example 3: According to the process conditions of Comparative Example 1, the types and amounts of the starting material, catalyst, epoxide, adsorbent, phosphoric acid and water were adjusted; Comparative Examples 4 to 6: According to the process conditions of Comparative Example 2, the types and amounts of the raw materials, catalyst, epoxide, adsorbent and water were adjusted; the results are shown in Table 3.

[0083] Table 3 Comparative Examples 3 to 6

[0084]

[0085] Comparative Examples 7 and 8

[0086] Examples 7 and 8 are based on the raw materials, proportions and process conditions of Example 2, except that only the temperature of the deodorization process in the deodorization kettle (the temperature of the material in the deodorization kettle when the steam generated by the steam evaporator is passed into the deodorization kettle) is adjusted, as shown in Table 4.

[0087] Table 4 Temperature of deodorization process

[0088] Group Temperature of deodorization process (℃) Example 2 100～120 Comparative Example 7 50～70 Comparative Example 8 140～155

[0089] Comparative Examples 9 and 10

[0090] Examples 9 and 10 are based on the raw materials, proportions and process conditions of Example 1, except that only the vacuum degree of the deodorization process in the deodorization kettle (the vacuum degree in the deodorization kettle during the process of the steam generated by the steam evaporator passing into the deodorization kettle) is adjusted, as shown in Table 5.

[0091] Table 5 Temperature of deodorization process

[0092] Group Vacuum degree of deodorization process (MPa) Example 1 -0.080～-0.090 Comparative Example 9 -0.050～-0.060 Comparative Example 10 -0.098～-0.100

[0093] The test results of the embodiments and comparative examples are shown in Table 6.

[0094] Table 6 Test results of embodiments and comparative examples

[0095]

[0096] As shown in Table 4, under the same conditions of raw materials, synthesis process conditions and post-treatment process, the aldehyde and ketone contents of the examples after deodorization by the deodorization preparation system of the present invention are reduced by an order of magnitude compared with the comparative examples without the deodorization process, and the odor level is reduced from 4 or even 4.5 to 1-1.5. The difference between comparative example 7 and embodiment 2 is that the deodorization process temperature is reduced from 100-120°C to 50-70°C. Due to the low temperature, the steam condenses into water and cannot carry aldehydes and ketones to volatilize and extract them in time. The content of aldehyde and ketone odor substances has increased by an order of magnitude, and the odor level has increased to 2, indicating that the deodorization effect is poor at low temperature. The difference between comparative example 8 and embodiment 2 is that the deodorization process temperature is increased from 100-120°C to 140-155°C. The deodorization process temperature is too high, and the polyether may decompose. The trace oxygen remaining in the steam or the deodorization kettle is easy to oxidize the material, so that the content of aldehydes and ketones in the product increases, and the odor level increases. The content of aldehydes and ketones odor substances has increased by an order of magnitude, and the odor level has increased to 2. The difference between comparative example 9 and example 1 is that the vacuum degree of the deodorization process is reduced from -0.080 to -0.090 MPa to -0.05 to -0.06 MPa (the steam feed flow rate is increased), and the steam water remains too much in the material, and the effect of removing aldehyde and ketone odor substances is reduced, and the content of aldehyde and ketone odor substances is increased by an order of magnitude, and the odor level is increased to 2. The difference between comparative example 10 and example 1 is that the vacuum degree of the deodorization process is reduced from -0.080 to -0.090 MPa to -0.098 to -0.100 MPa (the steam feed flow rate is reduced), the steam flow rate is greatly reduced, and the effect of removing aldehyde and ketone odor substances is significantly reduced, and the content of aldehyde and ketone odor substances is increased by an order of magnitude, and the odor level is increased to 3, indicating that the vacuum degree needs to be controlled within a reasonable range to improve the deodorization effect. It shows that the preparation system and process of the patent of the present invention can prepare an ideal low-odor polyether. Therefore, only by strictly controlling the temperature and vacuum degree of the deodorization process can the content of aldehyde and ketone odor substances be effectively reduced and low-odor polyether be prepared.

[0097] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a low-odor polyether, characterized in that: The preparation is carried out using a preparation system of low-odor polyether, comprising the following steps: (1) adding an alcohol initiator and a catalyst into a reaction kettle, raising the temperature, and adding an epoxide to react to obtain a crude polyether; (2) adding the crude polyether prepared in step (1) into a post-treatment kettle, adding acid and / or adsorbent for treatment, and filtering to obtain a refined polyether; (3) adding the refined polyether prepared in step (2) and steam without air into a deodorizing kettle at the same time, and performing deodorizing treatment at 75 to 130° C. and a vacuum degree of −0.070 to −0.095 MPa; finally, stopping the introduction of the steam, and performing vacuum dehydration to obtain a low-odor polyether; The preparation system comprises: A reaction kettle (100), wherein the reaction kettle (100) comprises a material feed pipe (110) and a polyether crude product discharge pipe (120); A post-treatment kettle (200), wherein the feed port of the post-treatment kettle (200) is connected to the crude polyether discharge pipe (120), and the post-treatment kettle (200) comprises a refined polyether discharge pipe (210); A deodorizing kettle (300), wherein the feed port of the deodorizing kettle (300) is connected to the refined polyether discharge pipe (210), the deodorizing kettle (300) comprises a mixer (310), an atomizer (320), a second external circulation pipe (340) and a finished product discharge port (330), the mixer (310) is directly connected to the atomizer (320), the finished product discharge port (330) is arranged at the bottom of the deodorizing kettle (300), one end of the second external circulation pipe (340) is connected to the finished product discharge port (330), and the other end is connected to the top of the deodorizing kettle (300); A steam generator (400), the steam generator (400) comprising a steam outlet pipe (410) and a first water inlet pipe (420), the steam outlet pipe (410) and the second external circulation pipe (340) both being connected to the mixer (310) on the deodorizing kettle (300); A water storage device (500), the water storage device (500) comprising a second water inlet pipe (520), a vacuum pipe (530), a nitrogen inlet pipe (540) and a gas distributor (510); the gas distributor (510) is located inside the water storage device (500) and is connected to the nitrogen inlet pipe (540) for dispersing nitrogen.

2. The preparation method according to claim 1, characterized in that: The alcohol initiator in step (1) is selected from at least one of allyl alcohol, methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol and trimethylolpropane.

3. The preparation method according to claim 1, characterized in that: The catalyst in step (1) is one of potassium hydroxide, sodium hydroxide, sodium methoxide, potassium methoxide or metallic sodium, and the amount of the catalyst is 1‰ to 5‰ of the total mass of the initiator alcohol and the epoxide.

4. The preparation method according to claim 1 or 2, characterized in that: The epoxide in step (1) is at least one of propylene oxide, ethylene oxide and butylene oxide.

5. The preparation method according to claim 3, characterized in that: The mass ratio of the propylene oxide to the butylene oxide and the ethylene oxide is 1:0-2:0-2.

6. The preparation method according to claim 1, characterized in that: The reaction temperature in step (1) is 80-130°C.

7. The preparation method according to claim 1, characterized in that: The adsorbent in step (2) is magnesium silicate, magnesium aluminum silicate or modified high-efficiency magnesium silicate adsorbent; the amount of the adsorbent is 2‰ to 20‰ of the total mass of the alcohol initiator and the epoxide.

8. The preparation method according to claim 7, characterized in that: The temperature for treatment with the adsorbent in step (2) is 60 to 80° C. and the time is 10 to 60 minutes.

9. The preparation method according to claim 1, characterized in that: In step (3), the deodorization treatment is carried out at 80 to 130° C. and a vacuum degree of -0.070 to -0.095 MPa for 1 to 5 hours.

10. The preparation method according to claim 1, characterized in that: The molecular weight of the low-odor polyether prepared in step (3) is 300 to 8000.

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