Preparation method for high-molecular-weight silane-modified polyether

Abstract

The present invention relates to the technical field of preparation of polyethers. Disclosed is a preparation method for a high-molecular-weight silane-modified polyether. The preparation method comprises the following steps: preparing a low-molecular-weight polyether polyol; preparing a medium-molecular-weight polyether polyol; preparing a high-molecular-weight polyether polyol; and carrying out an end capping reaction between the high-molecular-weight polyether polyol and a silane coupling agent to prepare a high-molecular-weight silane-modified polyether. According to the preparation method provided by the present invention, a high-molecular-weight polyether polyol is prepared from a polyol as an initiator and propylene oxide by means of a three-step method, and then a silane coupling agent is used for end capping to prepare a high-molecular-weight silane-modified polyether. In the present invention, the polyether is prepared by means of the three-step method, the molecular weight of the polyether polyol and the reaction temperature in each step are strictly controlled, and a small molecular alcohol and an antioxidant are added after the reaction, so that the prepared high-molecular-weight silane-modified polyether has low viscosity, strong storage stability, and small changes in viscosity and color during storage.

Description

A method for preparing high molecular weight silane-modified polyether Technical Field

[0001] This invention belongs to the field of polyether preparation technology, specifically relating to a method for preparing high molecular weight silane-modified polyether. Background Technology

[0002] Silane-modified polyethers are a novel type of organosilicon polymer. Polyether polyols are one of their important starting materials. Polyether polyols are usually obtained by ring-opening polymerization of epoxides such as ethylene oxide and propylene oxide in the presence of an initiator (such as a polyol). For example, using propylene glycol as an initiator, reacting with propylene oxide can yield polyether polyols of different molecular weights and functionalities. Silane coupling agents are also key raw materials for the synthesis of silane-modified polyethers. During the synthesis process, the alkoxy group of the silane coupling agent undergoes a condensation reaction with the terminal hydroxyl group of the polyether polyol. For example, the methoxy group (-OCH3) in the silane coupling agent reacts with the terminal hydroxyl group (-OH) of the polyether polyol under certain reaction conditions (such as the presence of a catalyst and appropriate temperature) to remove one molecule of methanol (CH3OH), thereby introducing the silane structure into the polyether segment. Silane-modified polyethers exhibit good adhesion to a variety of materials. It can bond both inorganic materials, such as glass and metals (aluminum, steel, etc.), and organic materials, such as plastics (PVC, PP, etc.) and wood. Therefore, silane-modified polyethers have wide applications in the construction, automotive, and electronics industries. For example, in the construction industry, silane-modified polyether sealants can firmly bond glass to aluminum alloy window frames, withstanding certain external forces and climate changes without detaching. In the automotive industry, it can be used for sealing and bonding automobiles. In the electronics industry, it can be used for the encapsulation and protection of electronic components.

[0003] High molecular weight silane-modified polyethers possess advantages such as excellent mechanical properties and strong stability. Mechanically, the higher molecular weight means longer and more complex molecular chains. During bonding, silane-modified polyether molecules can form more interaction points with the surface of the bonded materials, which is beneficial for improving bonding strength. Simultaneously, high molecular weight silane-modified polyethers have higher cohesive strength, better resisting external tensile and shear forces, are less prone to tearing, and maintain good sealing performance. In terms of stability, due to the higher molecular weight, the interactions between molecular chains are stronger, requiring higher energy to break the molecular chain structure. Therefore, it can better maintain its sealing and bonding performance under high-temperature environments, without rapidly decomposing or losing its adhesiveness. Furthermore, high molecular weight silane-modified polyethers have better resistance; their complex molecular structure makes it difficult for chemicals to penetrate into the molecular interior for reaction. High molecular weight silane-modified polyether sealants can better resist chemical corrosion, extending the service life of the sealant.

[0004] However, as the molecular weight of silane-modified polyethers increases, their viscosity also increases. Excessive viscosity increases the difficulty of processing and handling the polyether products, such as difficulties in mixing and stirring, and inconvenience in coating and application; it may even pose a risk of affecting product performance. Furthermore, some high-molecular-weight silane-modified polyethers also exhibit problems such as dark color, significant viscosity changes during storage, and severe color deepening. Therefore, the preparation of high-molecular-weight silane-modified polyethers with low viscosity, strong storage stability, and minimal changes in viscosity and color during storage is of great significance for their application. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for preparing high molecular weight silane-modified polyethers. The high molecular weight silane-modified polyethers prepared by the present invention have low viscosity, strong storage stability, and minimal changes in viscosity and color during storage.

[0006] This invention provides a method for preparing high molecular weight silane-modified polyether.

[0007] Specifically, a method for preparing a high molecular weight silane-modified polyether includes the following steps:

[0008] (1) Mix the polyol with the first catalyst, add the first propylene oxide dropwise, and carry out the first polymerization reaction. After the reaction is completed, the low molecular weight polyether polyol is obtained by post-treatment.

[0009] (2) The low molecular weight polyether polyol prepared in step (1) is mixed with the second catalyst, and the second propylene oxide is added dropwise to carry out the second polymerization reaction to obtain the medium molecular weight polyether polyol.

[0010] (3) Mix the medium molecular weight polyether polyol prepared in step (2) with the third catalyst, add the third propylene oxide dropwise, and carry out the third polymerization reaction to obtain the high molecular weight polyether polyol.

[0011] (4) The high molecular weight polyether polyol prepared in step (3) is mixed with a bismuth-containing catalyst, and then a silane coupling agent is added to carry out the end-capping reaction. After the reaction is completed, a small molecule alcohol and an antioxidant are added in sequence to obtain a high molecular weight silane-modified polyether.

[0012] The low molecular weight polyether polyol has a molecular weight of 300-800; the medium molecular weight polyether polyol has a molecular weight 2-10 times that of the low molecular weight polyether polyol; and the high molecular weight polyether polyol has a molecular weight 2-10 times that of the medium molecular weight polyether polyol.

[0013] The temperature of the first polymerization reaction is 110-120℃; the temperature of the second polymerization reaction is 125-145℃; the temperature of the third polymerization reaction is 125-145℃;

[0014] In step (4), the antioxidant is a phosphorus antioxidant and a phenolic antioxidant.

[0015] Preferably, the low molecular weight polyether polyol has a molecular weight of 350-800; the medium molecular weight polyether polyol has a molecular weight 3-9 times that of the low molecular weight polyether polyol; and the high molecular weight polyether polyol has a molecular weight 3-9 times that of the medium molecular weight polyether polyol.

[0016] Preferably, in step (1), the polyol includes one of propylene glycol, glycerol, and glycerol.

[0017] Preferably, in step (1), the first catalyst is an alkali metal catalyst, such as sodium hydroxide or potassium hydroxide. The amount of the first catalyst added is 0.1%-1% of the mass of the low molecular weight polyether polyol, such as 0.1%-0.8%, 0.1%-0.5%, 0.2%-0.3%, etc.

[0018] Preferably, in step (1), the post-treatment process is as follows: acid and adsorbent are added to the reaction system for treatment, and then the adsorbent is removed by dehydration.

[0019] Preferably, in step (2), the second catalyst is a bimetallic complex catalyst or a multimetallic complex catalyst. The amount of the second catalyst added is 0.0015%-0.015% of the mass of the low molecular weight polyether polyol; such as 0.0015%, 0.002%, 0.004%, 0.008%, 0.012%, 0.015%, etc.

[0020] Preferably, in step (3), the third catalyst is a bimetallic complex catalyst or a multimetallic complex catalyst. The amount of the third catalyst added is 0.0015%-0.015% of the mass of the medium molecular weight polyether polyol; such as 0.0015%, 0.002%, 0.004%, 0.008%, 0.012%, 0.015%, etc.

[0021] Preferably, in step (4), the bismuth-containing catalyst includes, but is not limited to, bismuth carboxylic acid, such as bismuth (2-ethylhexanoic acid), bismuth neodecanoate, or bismuth tetramethylpimelic acid.

[0022] Preferably, in step (4), the amount of the bismuth-containing catalyst added is 0.05%-0.2% of the mass of the high molecular weight silane-modified polyether, such as 0.08%, 0.1%, 0.15%, etc.

[0023] Preferably, in step (4), the temperature of the end-capping reaction is 70-90°C, and the time of the end-capping reaction is 1-5 hours.

[0024] Preferably, in step (4), the silane coupling agent is an isocyanate silane, such as propyltriethoxysilane or propyltrimethoxysilane.

[0025] Preferably, in step (4), the small molecule alcohol is selected from at least one of methanol, ethanol, propanol, isopropanol, butanol, and isobutanol.

[0026] Preferably, in step (4), the mass ratio of the phosphorus antioxidant to the phenolic antioxidant is 1:(0.5-2); more preferably, in step (4), the mass ratio of the phosphorus antioxidant to the phenolic antioxidant is 1:(0.8-1.5).

[0027] Preferably, in step (4), the phosphorus antioxidant includes tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168) and / or antioxidant 619; the phenolic antioxidant includes at least one of 2,6-di-tert-butyl-4-methylphenol (antioxidant BHT), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), and 2,4-di-tert-butylphenol 3-dodecylthiopropionate (antioxidant 1135).

[0028] Preferably, in step (4), the amount of antioxidant added is 0.04%-0.15% of the mass of the high molecular weight silane modified polyether, such as 0.05%, 0.08%, 0.1%, 0.15%, etc.

[0029] More specifically, a method for preparing a high molecular weight silane-modified polyether includes the following steps:

[0030] (1) Preparation of low molecular weight polyether polyol: Add the first catalyst and polyol to the reactor. After nitrogen purging, heat to 105-110℃ and start adding the first propylene oxide. During this process, the pressure is controlled at ≤0.25Mpa and the addition time is 20-30 minutes. After the reaction is normal, control the pressure at ≤0.30Mpa and the temperature at 110-120℃, and add the first propylene oxide at a uniform rate. After the addition is completed, mature until the pressure does not drop. Then cool down and degas, add acid solution for neutralization, add adsorbent for adsorption treatment, and finally filter to remove the adsorbent to obtain low molecular weight polyether polyol.

[0031] (2) Preparation of medium molecular weight polyether polyol: Add the second catalyst and the low molecular weight polyether polyol prepared in step (1) to the reactor. After nitrogen purging, heat to 125℃ and start adding the second propylene oxide. The addition time is 5-30 min. After the reaction is normal, control the feeding temperature to 135-145℃ and the pressure to <0.3 MPa. Add the second propylene oxide at a uniform rate. After the addition is completed, mature until the pressure does not drop. Finally, degas to obtain medium molecular weight polyether polyol.

[0032] (3) Preparation of high molecular weight polyether polyol: Add the third catalyst and the medium molecular weight polyether polyol prepared in step (2) to the reactor. After nitrogen purging, heat to 125℃ and start adding the third propylene oxide. The addition time is 5-30 min. After the reaction is normal, control the addition temperature to 135-145℃ and the pressure to <0.3 MPa. Add the third propylene oxide at a uniform rate. After the addition is completed, mature until the pressure does not drop. Finally, degas to obtain high molecular weight polyether polyol.

[0033] (4) Silane end-capping: The high molecular weight polyether polyol prepared in step (3) is added to the reactor. After nitrogen purging, the temperature is raised to 60-120℃ and a bismuth-containing catalyst is added. Then, a silane coupling agent is added and the reaction is carried out at 70-90℃ for 1-5 hours. After the reaction is completed, a small molecule alcohol is added and the reaction is continued for 1-3 hours. Then, an antioxidant is added and stirred to obtain a high molecular weight silane-modified polyether.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] This invention provides a method for preparing high molecular weight silane-modified polyethers. Using a polyol as an initiator, a three-step process with propylene oxide is employed to prepare a high molecular weight polyether polyol. The polyol is then capped using a silane coupling agent to obtain the high molecular weight silane-modified polyether. This invention utilizes a three-step polyether preparation method, strictly controlling the molecular weight of the polyether polyol and the reaction temperature in each step. Furthermore, the addition of a small molecule alcohol and an antioxidant after the reaction results in a high molecular weight silane-modified polyether with low viscosity, strong storage stability, and minimal changes in viscosity and color during storage. Detailed Implementation

[0036] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0037] Unless otherwise specified, the raw materials, reagents or apparatus used in the following examples and comparative examples are available from conventional commercial sources or can be obtained by existing known methods.

[0038] Example 1

[0039] A method for preparing a silane-modified polyether includes the following steps:

[0040] (1) Preparation of low molecular weight polypropylene glycol: Add potassium hydroxide catalyst (14.6g) and propylene glycol (1520g, 20mol) to the condensation reactor. The initiator is pumped from the storage tank to the reactor via a metering pump. After nitrogen purging once, the reactor is sealed, and the temperature is raised to 110℃ to start the trial addition of the first propylene oxide. During this process, the pressure is controlled at ≤0.25Mpa, and the trial addition takes about 25 minutes. After the reaction is normal, control the pressure at ≤0.30Mpa, and the temperature of the first polymerization reaction is 115-120℃. Add the remaining first propylene oxide at a uniform rate. After the first propylene oxide (6496g, 112mol) is added, close the propylene oxide discharge valve and the reactor feed valve and verify the quantity. Allow it to mature for about 120 minutes until the pressure does not drop. After maturation, cool down to 100℃, turn on the vacuum pump, and slowly open the vacuum valve to degas. The vacuum is -0.096Mpa, and normal degassing takes 30 minutes. The material was transferred to a post-processing reactor, where a calculated amount of phosphoric acid (30g) was added to neutralize potassium hydroxide, followed by 30g of adsorbent and 400g of water. After stirring to adsorb phosphate, the mixture was vacuum dehydrated. Part of the wastewater was reused, and the rest was discharged into the plant's wastewater treatment plant. After the dehydrated polyether was filtered through a closed filter to remove the adsorbent, post-processed low molecular weight polypropylene glycol (7986g) was obtained.

[0041] (2) Preparation of medium molecular weight polypropylene glycol: A bimetallic complex catalyst (0.7 g) and low molecular weight polypropylene glycol (1597.2 g) were added to a condensation reactor. The reactor was purged with nitrogen once, sealed, and heated to 125°C before adding the second propylene oxide. The reaction proceeded for 20 minutes at a pressure of 0.25 MPa and a temperature of 140-145°C. After the reaction proceeded normally, the temperature of the second polymerization reaction was controlled at 140-145°C, and the pressure was controlled at <0.3 MPa. The second propylene oxide was added at a uniform rate. After the second propylene oxide (a total of 10393.6 g, 179.2 mol) was added, the mixture was allowed to mature for 1 hour, then cooled to 100°C for degassing for 30 minutes. The mixture was then cooled to 70°C and discharged to obtain medium molecular weight polypropylene glycol (11990.57 g).

[0042] (3) Preparation of high molecular weight polypropylene glycol: A bimetallic complex catalyst (0.35 g) and medium molecular weight polypropylene glycol (749.43 g) were added to a condensation reactor. The reactor was purged with nitrogen three times, sealed, and heated to 125°C before adding third propylene oxide. The reaction proceeded for 20 minutes at a pressure of 0.25 MPa and a temperature of 140-145°C. After the reaction proceeded normally, the temperature of the third polymerization reaction was controlled at 140-145°C, and the pressure was controlled at <0.3 MPa. Third propylene oxide was added at a uniform rate. After the third propylene oxide (a total of 2250.4 g, 38.8 mol) was added, the mixture was allowed to mature for 1 hour, then cooled to 100°C for degassing for 30 minutes. The mixture was then cooled to 70°C and discharged to obtain high molecular weight polypropylene glycol (2999.86 g).

[0043] (4) Silane end-capping: High molecular weight polypropylene glycol (5999.73) was added to the reactor. After purging with nitrogen once, the temperature was raised to 60-120℃, and bismuth neodecanoate (6g) was added and stirred. Then, silane coupling agent was added dropwise. After the addition was complete, the temperature was maintained at 78-80℃ for 3 hours. After the temperature was maintained, methanol was added, and the reaction continued for 1-3 hours. After the temperature was maintained, antioxidant 619 (3g) and antioxidant BHT (3g) were added, stirred, cooled, and discharged.

[0044] Example 2

[0045] A method for preparing a silane-modified polyether includes the following steps:

[0046] (1) Preparation of low molecular weight polypropylene glycol: Add potassium hydroxide catalyst (24g) to the condensation reactor. Propylene glycol (1520g, 20mol) initiator is pumped from the storage tank to the reactor via a metering pump. Purge with nitrogen once, seal the reactor, and heat to 110℃ to begin trial addition of the first propylene oxide. During this process, the pressure is controlled at ≤0.25MPa, and the trial addition takes about 25 minutes. After the reaction is normal, control the pressure at ≤0.30MPa. The temperature of the first polymerization reaction is 110-115℃. Add the remaining first propylene oxide at a uniform rate. After the first propylene oxide (total 10480g, 180mol) is added, close the propylene oxide discharge valve and the reactor feed valve, and verify the quantity. Allow it to mature for about 120 minutes until the pressure no longer drops. After maturation, cool to 100℃, turn on the vacuum pump, and slowly open the vacuum valve to degas. The vacuum is -0.096MPa. Degas normally for 30 minutes. The material was transferred to a post-processing reactor, where a calculated amount of phosphoric acid (49.5g) was added to neutralize potassium hydroxide, followed by the addition of adsorbent (40g) and water (400g). After stirring to adsorb phosphate, the mixture was vacuum dehydrated. Part of the wastewater produced was reused, while the remainder was discharged into the plant's wastewater treatment plant. After the dehydrated polyether was filtered through a closed filter to remove the adsorbent, post-processed low molecular weight polypropylene glycol (11960g) was obtained.

[0047] (2) Preparation of medium molecular weight polypropylene glycol: A bimetallic complex catalyst (0.95 g) and low molecular weight polypropylene glycol (2392 g) were added to a condensation reactor. The reactor was purged with nitrogen once, sealed, and heated to 120°C to begin trial addition of the second propylene oxide. The reaction proceeded for 25 minutes at a pressure of 0.25 MPa and a temperature of 135-140°C. After the reaction proceeded normally, the temperature of the second polymerization reaction was controlled at 135-140°C, and the pressure was controlled at <0.3 MPa. The second propylene oxide was added at a uniform rate. After the second propylene oxide (a total of 15613.6 g, 269.2 mol) was added, the mixture was allowed to mature for 1 hour, then cooled to 100°C for degassing for 30 minutes. The mixture was then cooled to 70°C and discharged to obtain medium molecular weight polypropylene glycol (18006.35 g).

[0048] (3) Preparation of high molecular weight polypropylene glycol: A bimetallic complex catalyst (0.5 g) and medium molecular weight polypropylene glycol (1125.4 g) were added to a condensation reactor. The reactor was purged with nitrogen three times, sealed, and heated to 120°C before adding third propylene oxide. The reaction proceeded at 0.25 MPa and 135-140°C for 20 minutes. After the reaction proceeded normally, the temperature of the third polymerization reaction was controlled at 135-140°C, and the pressure was controlled at <0.3 MPa. Third propylene oxide was added at a uniform rate. After the third propylene oxide (3375.6 g, 58.2 mol) was added, the mixture was allowed to mature for 1 hour, then cooled to 100°C for degassing for 30 minutes. The mixture was then cooled to 70°C and discharged to obtain high molecular weight polypropylene glycol (4501.18 g).

[0049] (4) Silane end-capping: High molecular weight polypropylene glycol (5765.78g) was added to the reactor. After purging with nitrogen once, the temperature was raised to 60-120℃, bismuth neodecanoate (6g) was added and stirred, followed by the addition of silane coupling agent. After the addition was complete, the temperature was maintained at 78-80℃ for 3 hours. After the temperature was maintained, ethanol was added, and the reaction continued for 1-3 hours. After the temperature was maintained, antioxidant 619 (3g) and antioxidant 1076 (3g) were added, stirred, cooled, and discharged.

[0050] Comparative Example 1

[0051] A method for preparing a silane-modified polyether includes the following steps:

[0052] (1) Preparation of low molecular weight polypropylene glycol: Add potassium hydroxide catalyst (14.6g) and propylene glycol (1520g, 20mol) to the condensation reactor. The initiator is pumped from the storage tank to the reactor via a metering pump. After nitrogen purging once, the reactor is sealed, and the temperature is raised to 110℃ to start the trial addition of the first propylene oxide. During this process, the pressure is controlled at ≤0.25Mpa, and the trial addition takes about 25 minutes. After the reaction is normal, control the pressure at ≤0.30Mpa, and the temperature of the first polymerization reaction is 115-120℃. Add the remaining first propylene oxide at a uniform rate. After the first propylene oxide (6496g, 112mol) is added, close the propylene oxide discharge valve and the reactor feed valve and verify the quantity. Allow it to mature for about 120 minutes until the pressure does not drop. After maturation, cool down to 100℃, turn on the vacuum pump, and slowly open the vacuum valve to degas. The vacuum is -0.096Mpa, and normal degassing takes 30 minutes. The material was transferred to a post-processing reactor, where a calculated amount of phosphoric acid (30g) was added to neutralize potassium hydroxide, followed by 30g of adsorbent and 400g of water. After stirring to adsorb phosphate, the mixture was vacuum dehydrated. Part of the wastewater was reused, and the rest was discharged into the plant's wastewater treatment plant. After the dehydrated polyether was filtered through a closed filter to remove the adsorbent, post-processed low molecular weight polypropylene glycol (7986g) was obtained.

[0053] (2) Preparation of medium molecular weight polypropylene glycol: A bimetallic complex catalyst (0.60 g) and low molecular weight polypropylene glycol (1597.2 g) were added to a condensation reactor. The reactor was purged with nitrogen once, sealed, and heated to 125°C before adding the second propylene oxide. The reaction proceeded at 0.25 MPa and 140-145°C for 20 minutes. After the reaction proceeded normally, the temperature of the second polymerization reaction was controlled at 140-145°C, and the pressure was controlled at <0.3 MPa. The second propylene oxide was added at a uniform rate. After the second propylene oxide (a total of 1596.16 g, 27.52 mol) was added, the mixture was allowed to mature for 1 hour, then cooled to 100°C for degassing for 30 minutes. The mixture was then cooled to 70°C and discharged to obtain medium molecular weight polypropylene glycol (3193.56 g).

[0054] (3) Preparation of high molecular weight polypropylene glycol: A bimetallic complex catalyst (0.35 g) and medium molecular weight polypropylene glycol (199.6 g) were added to a condensation reactor. The reactor was purged with nitrogen three times, sealed, and heated to 125°C before adding third propylene oxide. The reaction proceeded for 20 minutes at a pressure of 0.25 MPa and a temperature of 140-145°C. After the reaction proceeded normally, the temperature of the third polymerization reaction was controlled at 140-145°C, and the pressure was controlled at <0.3 MPa. Third propylene oxide was added at a uniform rate. After the third propylene oxide (a total of 2800 g, 48.28 mol) was added, the mixture was allowed to mature for 1 hour, then cooled to 100°C for degassing for 30 minutes. The mixture was then cooled to 70°C and discharged to obtain high molecular weight polypropylene glycol (2999.87 g).

[0055] (4) Silane end-capping: High molecular weight polypropylene glycol (5999.73) was added to the reactor. After purging with nitrogen once, the temperature was raised to 60-120℃, and bismuth neodecanoate (6g) was added and stirred. Then, silane coupling agent was added dropwise. After the addition was complete, the temperature was maintained at 78-80℃ for 3 hours. After the temperature was maintained, methanol was added, and the reaction continued for 1-3 hours. After the temperature was maintained, antioxidant 619 (3g) and antioxidant BHT (3g) were added, stirred, cooled, and discharged.

[0056] Comparative Example 2

[0057] A method for preparing a silane-modified polyether includes the following steps:

[0058] (1) Preparation of low molecular weight polypropylene glycol: Add potassium hydroxide catalyst (14.6g) and propylene glycol (1520g, 20mol) to the condensation reactor. The initiator is pumped from the storage tank to the reactor via a metering pump. After nitrogen purging once, the reactor is sealed, and the temperature is raised to 110℃ to start the trial addition of the first propylene oxide. During this process, the pressure is controlled at ≤0.25Mpa, and the trial addition takes about 25 minutes. After the reaction is normal, control the pressure at ≤0.30Mpa, and the temperature of the first polymerization reaction is 115-120℃. Add the remaining first propylene oxide at a uniform rate. After the first propylene oxide (6496g, 112mol) is added, close the propylene oxide discharge valve and the reactor feed valve and verify the quantity. Allow it to mature for about 120 minutes until the pressure does not drop. After maturation, cool down to 100℃, turn on the vacuum pump, and slowly open the vacuum valve to degas. The vacuum is -0.096Mpa, and normal degassing takes 30 minutes. The material was transferred to a post-processing reactor, where a calculated amount of phosphoric acid (30g) was added to neutralize potassium hydroxide, followed by 30g of adsorbent and 400g of water. After stirring to adsorb phosphate, the mixture was vacuum dehydrated. Part of the wastewater was reused, and the rest was discharged into the plant's wastewater treatment plant. After the dehydrated polyether was filtered through a closed filter to remove the adsorbent, post-processed low molecular weight polypropylene glycol (7986g) was obtained.

[0059] (2) Preparation of medium molecular weight polypropylene glycol: A bimetallic complex catalyst (0.60 g) and low molecular weight polypropylene glycol (1597 g) were added to a condensation reactor. The reactor was purged with nitrogen once, sealed, and heated to 125°C. The second propylene oxide was then added on a trial basis. The reaction proceeded for 20 minutes at a pressure of 0.25 MPa and a temperature of 140-145°C. After the reaction proceeded normally, the temperature of the second polymerization reaction was controlled at 140-145°C, and the pressure was controlled at <0.3 MPa. The second propylene oxide was added at a uniform rate. After the second propylene oxide (a total of 1596.16 g, 27.52 mol) was added, the mixture was allowed to mature for 1 hour, then cooled to 100°C for degassing for 30 minutes. The mixture was then cooled to 70°C and discharged to obtain medium molecular weight polypropylene glycol (3193.56 g).

[0060] (3) Continue the preparation of medium molecular weight polypropylene glycol: Add bimetallic complex catalyst (0.15g) and medium molecular weight polypropylene glycol (199.6g) obtained in step (2) to the condensation reactor. Purify with nitrogen three times, seal the reactor, and start adding third propylene oxide at 125℃. When the pressure inside the reactor is 0.25MPa and the temperature is 140-145℃, the reaction is carried out for 20min. After the reaction is normal, control the temperature of the third polymerization reaction at 140-145℃ and the pressure at <0.3MPa, and add third propylene oxide at a uniform rate. After the third propylene oxide (a total of 200.1g, 3.45mol) is added, let it mature for 1 hour, then cool it to 100℃ to degas for 30 minutes, and then cool it to 70℃ to discharge the material to obtain medium molecular weight polypropylene glycol (399.75g).

[0061] (4) Preparation of high molecular weight polypropylene glycol: Add bimetallic complex catalyst (0.35g) and medium molecular weight polypropylene glycol (399.75g) obtained in step (3) to the condensation reactor. Purify with nitrogen three times, seal the reactor, and start adding fourth propylene oxide at 125℃. When the pressure inside the reactor is 0.25MPa and the temperature is 140-145℃, the reaction is carried out for 20min. After the reaction is normal, control the temperature of the fourth polymerization reaction at 140-145℃ and the pressure at <0.3MPa, and add fourth propylene oxide at a uniform rate. After the fourth propylene oxide (a total of 2600.14g, 44.83mol) is added, let it mature for 1 hour, then cool it to 100℃ to degas for 30 minutes, and then cool it to 70℃ to discharge the material to obtain high molecular weight polypropylene glycol (3000.05g).

[0062] (4) Silane end-capping: High molecular weight polypropylene glycol (5999.73) was added to the reactor. After purging with nitrogen once, the temperature was raised to 60-120℃, and bismuth neodecanoate (6g) was added and stirred. Then, silane coupling agent was added dropwise. After the addition was complete, the temperature was maintained at 78-80℃ for 3 hours. After the temperature was maintained, methanol was added, and the reaction continued for 1-3 hours. After the temperature was maintained, antioxidant 619 (3g) and antioxidant BHT (3g) were added, stirred, cooled, and discharged.

[0063] Comparative Example 3

[0064] A method for preparing a silane-modified polyether includes the following steps:

[0065] (1) Preparation of low molecular weight polypropylene glycol: Add potassium hydroxide catalyst (24g) to the condensation reactor. Propylene glycol (1520g, 20mol) initiator is pumped from the storage tank to the reactor via a metering pump. Purge with nitrogen once, seal the reactor, and heat to 110℃ to begin trial addition of the first propylene oxide. During this process, the pressure is controlled at ≤0.25MPa, and the trial addition takes about 25 minutes. After the reaction is normal, control the pressure at ≤0.30MPa. The temperature of the first polymerization reaction is 115-120℃. Add the remaining first propylene oxide at a uniform rate. After the first propylene oxide (total 10480g, 180mol) is added, close the propylene oxide discharge valve and the reactor feed valve, and verify the quantity. Allow it to mature for about 120 minutes until the pressure no longer drops. After maturation, cool to 100℃, turn on the vacuum pump, and slowly open the vacuum valve to degas. The vacuum is -0.096MPa. Degas normally for 30 minutes. The material was transferred to a post-processing reactor, where a calculated amount of phosphoric acid (49.5g) was added to neutralize potassium hydroxide, followed by the addition of adsorbent (40g) and water (400g). After stirring to adsorb phosphate, the mixture was vacuum dehydrated. Part of the wastewater produced was reused, while the remainder was discharged into the plant's wastewater treatment plant. After the dehydrated polyether was filtered through a closed filter to remove the adsorbent, post-processed low molecular weight polypropylene glycol (11960g) was obtained.

[0066] (2) Preparation of medium molecular weight polypropylene glycol: A bimetallic complex catalyst (0.9 g) and low molecular weight polypropylene glycol (2392 g) were added to a condensation reactor. The reactor was purged with nitrogen once, sealed, and heated to 125°C. The second propylene oxide was then added on a trial basis. The reaction proceeded for 20 minutes at a pressure of 0.25 MPa and a temperature of 140-145°C. After the reaction proceeded normally, the temperature of the second polymerization reaction was controlled at 140-145°C, and the pressure was controlled at <0.3 MPa. The second propylene oxide was added at a uniform rate. After the second propylene oxide (a total of 26401.6 g, 455.2 mol) was added, the mixture was allowed to mature for 1 hour, then cooled to 100°C for degassing for 30 minutes. The mixture was then cooled to 70°C and discharged to obtain medium molecular weight polypropylene glycol (28794.28 g).

[0067] (3) Preparation of high molecular weight polypropylene glycol: A bimetallic complex catalyst (0.35 g) and medium molecular weight polypropylene glycol (1799.64 g) were added to a condensation reactor. The reactor was purged with nitrogen three times, sealed, and heated to 125°C before adding third propylene oxide. The reaction proceeded at a pressure of 0.25 MPa and a temperature of 140-145°C for 20 minutes. After the reaction proceeded normally, the temperature of the third polymerization reaction was controlled at 140-145°C, and the pressure was controlled at <0.3 MPa. Third propylene oxide was added at a uniform rate. After the third propylene oxide (a total of 1948.8 g, 33.6 mol) was added, the mixture was allowed to mature for 1 hour, then cooled to 100°C for degassing for 30 minutes. The mixture was then cooled to 70°C and discharged to obtain high molecular weight polypropylene glycol (3748.62 g).

[0068] (4) Silane end-capping: High molecular weight polypropylene glycol (5999.73) was added to the reactor. After purging with nitrogen once, the temperature was raised to 60-120℃, and bismuth neodecanoate (6g) was added and stirred. Then, silane coupling agent was added dropwise. After the addition was complete, the temperature was maintained at 78-80℃ for 3 hours. After the temperature was maintained, methanol was added, and the reaction continued for 1-3 hours. After the temperature was maintained, antioxidant 619 (3g) and antioxidant BHT (3g) were added, stirred, cooled, and discharged.

[0069] The molecular weights in Examples 1-2 and Comparative Examples 1-3 are shown in Table 1.

[0070] Table 1

[0071] Comparative Example 4

[0072] Comparative Example 4 provides a method for preparing silane-modified polyether. The difference between Comparative Example 4 and Example 1 is as follows: In step (1), after sealing the reactor, the temperature is raised to 100°C and the first propylene oxide is added on a trial basis. The pressure is controlled at ≤0.25 MPa during this process, and the trial addition takes about 25 minutes. After the reaction is normal, the pressure is controlled at ≤0.30 MPa, the temperature of the first polymerization reaction is 100-105°C, and the remaining first propylene oxide is added at a uniform rate; In step (2), after sealing the reactor, the temperature is raised to 105°C and the second propylene oxide is added on a trial basis. When the pressure inside the reactor is 0.25 MPa and the temperature is 105-110°C, the reaction is carried out for 20 minutes. After the reaction proceeds normally, the temperature of the second polymerization reaction is controlled at 110-115℃, and the pressure is controlled at <0.3 MPa. The second propylene oxide is added at a uniform rate. In step (3), after sealing the reactor, the temperature is raised to 105℃ to start adding the third propylene oxide. When the pressure inside the reactor is 0.25 MPa and the temperature is 105-110℃, the reaction is carried out for 20 minutes. After the reaction proceeds normally, the temperature of the third polymerization reaction is controlled at 105-110℃, and the pressure is controlled at <0.3 MPa. The third propylene oxide is added at a uniform rate. The remaining steps are the same as in Example 1.

[0073] Comparative Example 5

[0074] Comparative Example 5 provides a method for preparing silane-modified polyether. The difference between Comparative Example 5 and Example 1 is as follows: In step (1), after sealing the reactor, the temperature is raised to 125°C and the first propylene oxide is added on a trial basis. The pressure is controlled at ≤0.25 MPa during this process, and the trial addition takes about 25 minutes. After the reaction is normal, the pressure is controlled at ≤0.30 MPa, the temperature of the first polymerization reaction is 140-145°C, and the remaining first propylene oxide is added at a uniform rate; In step (2), after sealing the reactor, the temperature is raised to 125°C and the second propylene oxide is added on a trial basis. When the pressure inside the reactor is 0.25 MPa and the temperature is 140-145°C, the reaction is carried out for 20 minutes. After the reaction proceeds normally, the temperature of the second polymerization reaction is controlled at 140-145℃, and the pressure is controlled at <0.3 MPa. The second propylene oxide is added at a uniform rate. In step (3), after sealing the reactor, the temperature is raised to 125℃ to start adding the third propylene oxide. When the pressure inside the reactor is 0.25 MPa and the temperature is 140-145℃, the reaction is carried out for 20 minutes. After the reaction proceeds normally, the temperature of the third polymerization reaction is controlled at 140-145℃, and the pressure is controlled at <0.3 MPa. The third propylene oxide is added at a uniform rate. The remaining steps are the same as in Example 1.

[0075] Comparative Example 6

[0076] Comparative Example 6 provides a method for preparing silane-modified polyether. The difference between Comparative Example 6 and Example 1 is as follows: In step (1), after sealing the reactor, the temperature is raised to 115°C and the first propylene oxide is added on a trial basis. The pressure is controlled at ≤0.25 MPa during this process, and the trial addition takes about 25 minutes. After the reaction is normal, the pressure is controlled at ≤0.30 MPa, the temperature of the first polymerization reaction is 115-120°C, and the remaining first propylene oxide is added at a uniform rate; In step (2), after sealing the reactor, the temperature is raised to 115°C and the second propylene oxide is added on a trial basis. The reaction is carried out when the pressure inside the reactor is 0.25 MPa and the temperature is 115-120°C for 20 minutes. After the reaction proceeds normally, the temperature of the second polymerization reaction is controlled at 115-120℃, and the pressure is controlled at <0.3 MPa. The second propylene oxide is added at a uniform rate. In step (3), after sealing the reactor, the temperature is raised to 115℃ to start adding the third propylene oxide. When the pressure inside the reactor is 0.25 MPa and the temperature is 115-120℃, the reaction is carried out for 20 minutes. After the reaction proceeds normally, the temperature of the third polymerization reaction is controlled at 115-120℃, and the pressure is controlled at <0.3 MPa. The third propylene oxide is added at a uniform rate. The remaining steps are the same as in Example 1.

[0077] Comparative Example 7

[0078] The difference between Comparative Example 7 and Example 1 is that in step (4), antioxidant 619 (6g) is added after the heat preservation is completed, and the mixture is stirred, cooled, and discharged. The remaining steps are the same as in Example 1.

[0079] Comparative Example 8

[0080] The difference between Comparative Example 8 and Example 1 is that in step (4), after the heat preservation is completed, antioxidant BHT (6g) is added, and the mixture is stirred, cooled, and discharged. The remaining steps are the same as in Example 1.

[0081] Product effectiveness test

[0082] The silane-modified polyethers prepared in Examples 1-2 and Comparative Examples 1-8 were subjected to performance tests, mainly including molecular weight, viscosity, color, storage stability, free isocyanate content, and mechanical properties (strength and elongation). Specific test methods are as follows:

[0083] (1) Color test: The color test was performed using the platinum-cobalt colorimetric method;

[0084] (2) Viscosity: The viscosity was determined using a Bollerfeld cone-plate viscometer.

[0085] (3) Storage stability: The silane-modified polyether product was placed in a 120℃ forced-air drying oven for 6 hours and the viscosity change was tested.

[0086] (4) The content of free isocyanate was tested by liquid chromatography;

[0087] (5) Mechanical properties (strength, elongation) refer to GB / T 528-2009 method.

[0088] The test results are shown in Tables 2 and 3.

[0089] Table 2

[0090] As shown in Table 2, the silane-modified polyether prepared in the embodiments of the present invention has a light color and low viscosity. After high-temperature treatment, its color and viscosity change little, and it exhibits strong high-temperature stability. Analysis of Comparative Examples 1-3 shows that when the three-step polyether preparation is not used, or when the molecular weight of the polyether in each step does not meet the requirements, it is not only difficult to prepare a polyether with the preset molecular weight, but it also affects the color, viscosity, and thermal stability of the silane-modified polyether. Analysis of Comparative Examples 4-6 shows that when the reaction temperature is outside the range during the polyether preparation process, it severely affects the actual molecular weight, making it impossible to prepare a polyether with the target molecular weight; it also increases the viscosity of the final silane-modified polyether, worsens its storage stability, and causes significant changes in viscosity and color during storage. Analysis of Comparative Examples 7 and 8 shows that phosphorus antioxidants and phenolic antioxidants have a synergistic effect in the preparation of silane-modified polyethers. Although the combination of the two does not affect the initial color of the silane-modified polyether, it will significantly improve the storage stability of the silane-modified polyether and delay the color change of the silane-modified polyether during storage.

[0091] Furthermore, analysis of the peak molecular weight (Mp) and designed molecular weight in the examples and comparative examples shows that the actual peak molecular weight (Mp) in the examples of this invention is close to the designed molecular weight, enabling the preparation of silane-modified polyethers with the required molecular weight. In the comparative examples, the peak molecular weight (Mp) of the silane-modified polyethers all show a certain difference from the designed molecular weight. Specifically, the peak molecular weight (Mp) of Comparative Examples 1 and 2 is significantly lower than the designed molecular weight. This is because in Comparative Example 1, the molecular weight difference between the second and first steps is small, only doubling. When using DMC catalyst, the initial catalyst passivation to the initial activation stage produces ultra-high molecular weight byproducts. The smaller the molecular weight difference, the higher the content of ultra-high molecular weight byproducts, and the lower the peak molecular weight (Mp) of the final product. Similarly, in Comparative Example 2, the molecular weight difference between the second and first steps is small, only doubling, and the molecular weight in the third step is also only doubling, resulting in Comparative Example 2 having a much smaller molecular weight than Comparative Example 1. The reason why the peak molecular weight (Mp) of Comparative Example 5 is lower than the designed molecular weight is that the reaction temperature was too high during the first synthesis step. When propylene oxide polymerizes under the alkaline catalyst KOH, excessively high temperatures can lead to isomerization, forming allyl alcohol or propenol. The generated allyl alcohol or propenol reacts with propylene oxide, consuming it and causing a decrease in molecular weight. Ultimately, this results in a product with a molecular weight significantly lower than the designed molecular weight. Comparative Examples 4 and 6 show that in the second and third steps, the reaction temperatures were too low, while the molecular weight gradually increased, leading to higher viscosity and poor mass transfer in the reaction system. This resulted in uneven reaction and an increase in components with excessively high or low molecular weights, causing a decrease in the peak molecular weight (Mp) of the product. The lower the reaction temperature, the more significant the decrease. Therefore, strictly controlling the molecular weight of the polyether polyol and the reaction temperature in each step is crucial for preparing silane-modified polyethers that meet the set molecular weight requirements; both are indispensable.

[0092] Table 3

[0093] As shown in Table 3, the silane-modified polyether prepared in the embodiments of the present invention exhibits excellent mechanical properties and is free of free isocyanates. The addition of small molecule alcohols can eliminate free isocyanates in the silane-modified polyether product, increasing the viscosity stability and color stability of the product. Furthermore, as shown in Table 2, the higher the molecular weight of the silane-modified polyether, the higher its elongation.

[0094] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing high molecular weight silane-modified polyether, characterized in that, Includes the following steps: (1) Mix the polyol with the first catalyst, add the first propylene oxide dropwise, and carry out the first polymerization reaction. After the reaction is completed, the low molecular weight polyether polyol is obtained by post-treatment. (2) The low molecular weight polyether polyol prepared in step (1) is mixed with the second catalyst, and the second propylene oxide is added dropwise to carry out the second polymerization reaction to obtain the medium molecular weight polyether polyol. (3) Mix the medium molecular weight polyether polyol prepared in step (2) with the third catalyst, add the third propylene oxide dropwise, and carry out the third polymerization reaction to obtain the high molecular weight polyether polyol. (4) The high molecular weight polyether polyol prepared in step (3) is mixed with a bismuth-containing catalyst, and then a silane coupling agent is added to carry out the end-capping reaction. After the reaction is completed, a small molecule alcohol and an antioxidant are added in sequence to obtain a high molecular weight silane-modified polyether. The low molecular weight polyether polyol has a molecular weight of 300-800; the medium molecular weight polyether polyol has a molecular weight 2-10 times that of the low molecular weight polyether polyol; and the high molecular weight polyether polyol has a molecular weight 2-10 times that of the medium molecular weight polyether polyol. The temperature of the first polymerization reaction is 110-120℃; the temperature of the second polymerization reaction is 125-145℃; the temperature of the third polymerization reaction is 125-145℃; In step (4), the antioxidant is a phosphorus antioxidant and a phenolic antioxidant.

2. The preparation method according to claim 1, characterized in that, The low molecular weight polyether polyol has a molecular weight of 350-800; the medium molecular weight polyether polyol has a molecular weight 3-9 times that of the low molecular weight polyether polyol; and the high molecular weight polyether polyol has a molecular weight 3-9 times that of the medium molecular weight polyether polyol.

3. The preparation method according to claim 1 or 2, characterized in that, In step (1), the first catalyst is an alkali metal catalyst; in step (2), the second catalyst is a bimetallic complex catalyst or a multimetallic complex catalyst; in step (3), the third catalyst is a bimetallic complex catalyst or a multimetallic complex catalyst.

4. The preparation method according to claim 1 or 2, characterized in that, In step (4), the temperature of the end-capping reaction is 70-90°C, and the time of the end-capping reaction is 1-5 hours.

5. The preparation method according to claim 1 or 2, characterized in that, In step (4), the silane coupling agent is isocyanate silane.

6. The preparation method according to claim 1 or 2, characterized in that, In step (4), the small molecule alcohol is selected from at least one of methanol, ethanol, propanol, isopropanol, butanol, and isobutanol.

7. The preparation method according to claim 1 or 2, characterized in that, In step (4), the mass ratio of the phosphorus antioxidant to the phenolic antioxidant is 1:(0.5-2).

8. The preparation method according to claim 7, characterized in that, In step (4), the mass ratio of the phosphorus antioxidant to the phenolic antioxidant is 1:(0.8-1.5).

9. The preparation method according to claim 7, characterized in that, In step (4), the phosphorus antioxidant includes tris(2,4-di-tert-butylphenyl) phosphite and / or antioxidant 619; the phenolic antioxidant includes at least one of 2,6-di-tert-butyl-4-methylphenol, octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 2,4-di-tert-butylphenol 3-dodecylthiopropionate.

10. The preparation method according to claim 8 or 9, characterized in that, In step (4), the amount of antioxidant added is 0.04%-0.15% of the mass of the high molecular weight silane modified polyether.

Images