An underwater curing polyurethane sealant and a method for preparing the same

Abstract

The present application relates to the technical field of underwater curable sealant, in particular to an underwater curable polyurethane sealant and a preparation method thereof.An underwater curable polyurethane sealant comprises glue, dioctyl terephthalate, wetting dispersant, water removing agent, thixotropic agent, filler, magnesium fluoride, carbon black and ultraviolet absorber; wherein the glue comprises the following raw materials in mass fraction: polyoxyethyl polyoxypropyl glycerol ether, polypropylene glycol, bio-based polyol, isocyanate propyl triethoxy silane, diphenyl methane diisocyanate, drier, coupling agent, defoaming agent, diluent and latent curing agent.The underwater curable polyurethane sealant of the present application can not only be quickly cured underwater, but also can quickly form a stable bonding interface after being cured underwater, effectively resist the penetration of water molecules, thereby ensuring long-term sealing effect and structural stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underwater curable sealant, in particular to an underwater curable polyurethane sealant and a preparation method thereof. BACKGROUND

[0002] In underwater engineering, the curing time and bonding strength of sealant are important indicators for evaluating its performance. Traditional underwater sealant, especially polyurethane sealant, is significantly affected by environmental factors in terms of curing time and bonding strength. Although it exhibits good adhesion and curing speed in dry environments, the curing time of polyurethane sealant tends to be prolonged and the bonding strength tends to decrease in underwater environments due to the penetration and hindrance of water molecules. Especially when the sealant is in a long-term immersion state, the bonding strength will further decrease, which may lead to sealing failure, making it difficult to meet the special needs of ship navigation at sea, underwater facility maintenance, etc.

[0003] With the continuous development of marine engineering and underwater technology, the performance requirements for underwater sealant are becoming higher and higher. In particular, in the fields of shipbuilding, underwater pipeline laying, and offshore platform construction, there is a need for a sealant material that can quickly cure and bond with high strength underwater. SUMMARY

[0004] In order to shorten the curing time of polyurethane sealant underwater and improve the bonding strength of polyurethane sealant underwater, the present application provides an underwater curable polyurethane sealant and a preparation method thereof. The underwater curable polyurethane sealant of the present application not only can quickly cure underwater, but also can quickly form a stable bonding interface after curing underwater, effectively resisting the penetration of water molecules, thereby ensuring long-term sealing effect and structural stability.

[0005] In a first aspect, the present application provides an underwater curable polyurethane sealant using the following technical solution:

[0006] An underwater curable polyurethane sealant comprises the following components by mass percentage: 28.41-39.52% glue, 20-25% dioctyl terephthalate, 0.1-0.5% wetting dispersant, 1-2% water removal agent, 30-40% thixotropic agent, 4-6% filler, 1-2% magnesium fluoride, 0.1-1% carbon black, and 0.1-0.3% ultraviolet absorber.

[0007] The glue includes the following raw materials in mass fraction: 9-10 parts of polyoxyethyl polyoxypropyl glycerol ether, 12-15 parts of polypropylene glycol, 0.1-0.5 parts of bio-based polyol, 0.1-0.5 parts of propyl triethoxy silane isocyanate, 0.1-0.2 parts of gamma-glycidyl ether oxypropyl trimethoxysilane, 3-5 parts of diphenyl methane diisocyanate, 0.01-0.02 parts of a drying agent, 0.1-0.3 parts of a defoaming agent, 3-6 parts of a diluent, and 1-2 parts of a latent curing agent.

[0008] In the above technical solution, the present application selects dioctyl terephthalate as a plasticizer of the sealant, which significantly improves the flexibility and water resistance of the sealant; by introducing carbon black, magnesium fluoride and ultraviolet absorber, the weather resistance and anti-aging performance of the sealant are enhanced, especially the introduction of carbon black and magnesium fluoride can promote the sealant to quickly form a stable bonding interface and maintain high bonding strength of the sealant, which meets the special requirements of underwater engineering on the sealant.

[0009] The present application further selects polyoxyethyl polyoxypropyl glycerol ether, polypropylene glycol, bio-based polyol and diphenyl methane diisocyanate as main materials of the glue, and selects propyl triethoxy silane isocyanate and gamma-glycidyl ether oxypropyl trimethoxysilane as silane coupling agents, so that the glue has good curing performance and bonding strength under water. Among them, polyoxyethyl polyoxypropyl glycerol ether and polypropylene glycol serve as main polyether polyols, providing good adhesion; the introduction of bio-based polyol significantly enhances the flexibility and bonding strength of the glue; on this basis, diphenyl methane diisocyanate is further introduced to react with polyether polyols to form polyurethane, further enhancing the curing performance and bonding strength of the glue. Meanwhile, propyl triethoxy silane isocyanate can react with active functional groups such as -OH, -NH2 and -SH to synthesize new functional small molecules or hybrid functional polymers, giving the sealant and the substrate better adhesion and wet adhesion, and gamma-glycidyl ether oxypropyl trimethoxysilane can further improve the bonding strength of the sealant in a humid environment.

[0010] Preferably, the glue further includes 0.3-0.5 parts of a curing aid, which is a mixture of trimethylolpropane triglycidyl ether and dodecyl polyoxyethylene ether in a mass ratio of 1:(1-1.37).

[0011] In the above technical solution, the present application selects trimethylolpropane triglycidyl ether and dodecyl polyoxyethylene ether as a curing aid, which can effectively promote the curing reaction of polyurethane, further shorten the curing time, and further improve the bonding strength after curing, so that the glue can quickly react in an underwater environment to form a stable cross-linked structure, thereby achieving better rapid curing and high bonding strength.

[0012] Preferably, the adhesive comprises the following raw materials in parts by weight: 9.43 parts polyoxyethyl polyoxypropyl glycerol ether, 13.72 parts polypropylene glycol, 0.3 parts bio-based polyol, 0.3 parts propyltriethoxysilane isocyanate, 0.15 parts γ-glycidyl etheroxypropyltrimethoxysilane, 4.01 parts diphenylmethane diisocyanate, 0.012 parts drying agent, 0.2 parts defoamer, and 4.32 parts...

[0013] Diluent, 1.1 parts latent curing agent, 0.37 parts curing aid.

[0014] In the above technical solution, this application further optimizes the amount of each raw material in the adhesive, which effectively ensures that the adhesive forms a more uniform cross-linked network structure during underwater curing, effectively preventing the penetration of water molecules and ensuring the long-term stability and reliability of the sealant.

[0015] Preferably, the method for preparing the adhesive includes the following steps:

[0016] Step s1: Mix polyoxyethyl polyoxypropyl glycerol ether, polypropylene glycol and bio-based polyol according to the formula, heat to 110-115℃, and when the temperature reaches 110-115℃, dehydrate under vacuum. When the moisture content of the dehydrated mixture is below 0.05%, stop heating and cool down.

[0017] Step s2: Lower the temperature of the material obtained in step s1 to 80-85℃, and slowly add propyltriethoxysilane isocyanate and diphenylmethane diisocyanate in portions. The total feeding time should be controlled within 30 minutes. After the addition is complete, keep the reaction at 80-85℃ for 1.5-2 hours.

[0018] Step s3: Cool the material obtained in step s2 to 65-70℃, then add the remaining raw materials, continue stirring for 30 minutes, and then cool the material to 55-60℃ to obtain the adhesive.

[0019] In the above technical solution, this application ensures the stable synthesis of polyurethane prepolymer by controlling the reaction temperature and time, while avoiding the occurrence of side reactions, thereby improving the adhesive performance of the glue.

[0020] Preferably, step s1 involves stirring at a speed of 180-220 r / min and dehydrating under vacuum at a vacuum degree of -0.09 to -0.1 MPa.

[0021] In the above technical solution, this application reduces the interference of water molecules on the polyurethane curing reaction by controlling the stirring speed and vacuum degree, thereby improving the quality of the final product.

[0022] Preferably, the underwater curing polyurethane sealant comprises the following components by weight percentage: 33.912% adhesive, 22.028% dioctyl terephthalate, 0.33% wetting and dispersing agent, 1.38% dehydrating agent, 35.16% thixotropic agent, 5.16% filler, 1.32% magnesium fluoride, 0.5% carbon black, and 0.21% ultraviolet absorber.

[0023] In the above technical solution, this application further optimizes the amount of each raw material in the sealant to ensure that the sealant has a faster curing time and higher bonding strength in the underwater environment.

[0024] Preferably, the dehydrating agent is molecular sieve activated powder.

[0025] In the above technical solution, the activated molecular sieve powder possesses a high specific surface area, uniform pore size distribution, and excellent chemical stability, which gives it a strong selective adsorption capacity, enabling deep drying and dehydration and preventing the formation of air bubbles in the sealant at its source. Furthermore, the activated molecular sieve powder can also increase the smoothness of the sealant and improve its uniformity, strength, and other physical properties.

[0026] Preferably, the latent curing agent is latent curing agent WL-1031.

[0027] In the above technical solution, the latent curing agent WL-1031 is an imine compound with special chain extender and crosslinking agent functions. It can not only be used as a latent curing agent for moisture-curing polyurethane to further accelerate the surface drying time of the product, but also as an antifoaming agent to solve the problem of bubbles generated during the construction of sealant.

[0028] Preferably, the thixotropic agent is thixotropic powder B50.

[0029] In the above technical solution, thixotropic powder B50 has excellent dispersibility and a particle size of less than 0.07μm, which can provide the sealant with better anti-sagging and anti-settling properties.

[0030] Secondly, the preparation method of the underwater curing polyurethane sealant provided in this application adopts the following technical solution:

[0031] A method for preparing an underwater curing polyurethane sealant includes the following steps:

[0032] Step 1: Mix dioctyl terephthalate and wetting and dispersing agent according to the formula, then slowly add plasticizer, wetting and dispersing agent, dehydrating agent, thixotropic agent, filler, magnesium fluoride, carbon black and ultraviolet absorber. The total feeding time should be controlled within 30 minutes, and then slowly stir for 40 minutes.

[0033] Step 2: Add glue to the material obtained in Step 1, then continue to stir until uniform. Next, perform vacuum degassing for 50-60 minutes, then stop stirring to obtain underwater curing polyurethane sealant.

[0034] Preferably, step 1 involves stirring at a speed of 60-80 r / min, and step 2 involves stirring at a speed of 180-220 r / min. Step 2 involves first performing vacuum degassing at -0.06 to -0.07 MPa for 35-40 min, and then performing vacuum degassing at -0.095 to -0.09 MPa for 15-20 min.

[0035] In the above technical solution, this application ensures the uniform mixing and stable performance of the sealant through the above preparation method. The final underwater curing polyurethane sealant not only has excellent curing speed and bonding strength, but also has good weather resistance and anti-aging properties in the underwater environment, meeting the special requirements of underwater engineering for sealants.

[0036] In summary, this application includes at least one of the following beneficial technical effects:

[0037] 1. By introducing carbon black and magnesium fluoride into the sealant, this application not only enhances the sealant's weather resistance and anti-aging properties, but also promotes the rapid formation of a stable bonding interface, maintains the sealant's high bonding strength, and meets the special requirements of underwater engineering for sealants.

[0038] 2. This application, by further introducing bio-based polyols into the basis of polyether polyols, not only improves the environmental performance of the sealant, but also significantly enhances the flexibility and bonding strength of the adhesive.

[0039] 3. This application, by adding a curing aid composed of trimethylolpropane triglycidyl ether and dodecyl polyoxyethylene ether to the sealant, can better shorten the curing time and further improve the bond strength after curing, thereby achieving better rapid curing and high bond strength. Detailed Implementation

[0040] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0041] Preparation Example 1

[0042] An adhesive for sealing, comprising polyoxyethyl polyoxypropyl glycerol ether, polypropylene glycol, bio-based polyol, propyltriethoxysilane isocyanate, γ-glycidyl etheroxypropyltrimethoxysilane, diphenylmethane diisocyanate, a drying agent, a defoamer, a diluent, and a latent curing agent.

[0043] Among them, polyoxyethyl polyoxypropyl glycerol ether is the polyether polyol ET34-08 of CNOOC Shell Petrochemicals Co., Ltd.

[0044] Among them, polypropylene glycol is the polyether polyol ED56-200 of CNOOC Shell Petrochemicals Co., Ltd.

[0045] Among them, the bio-based polyol is LC-140, a plant oil polyol from Guangzhou Longchi New Material Technology Co., Ltd.

[0046] Among them, propyl isocyanate triethoxysilane is γ-isocyanate propyl triethoxysilane Siwin-AL32 from Nanjing Silicon Innovation Materials Co., Ltd.

[0047] Among them, γ-glycidyl etheroxypropyltrimethoxysilane is the coupling agent KH-560 of Dongguan Chenfeng New Materials Co., Ltd.

[0048] Among them, diphenylmethane diisocyanate is Wanhua Chemical Group Co., Ltd.'s MDI-50.

[0049] Among them, the drying agent is T-12 from Guangzhou Longchi New Material Technology Co., Ltd.

[0050] The defoamer used is DF-682 from Guangzhou Shenlan Polymer Co., Ltd.

[0051] The diluent used is EGDA from Guangdong Hongchuan New Materials Co., Ltd.

[0052] Among them, the latent curing agent is WL-1031 from Guangzhou Longchi New Material Technology Co., Ltd.

[0053] The preparation method of the adhesive includes the following steps:

[0054] Step s1: Add polyoxyethyl polyoxypropyl glycerol ether, polypropylene glycol, and bio-based polyol to a three-necked flask according to the formula. Turn on the stirrer and stir at a speed of 200 r / min. Turn on the electric furnace to heat to 110°C. When the temperature reaches 110°C, turn on the vacuum pump and dehydrate under vacuum of -0.1 MPa. When the moisture content of the dehydrated mixture is below 0.05%, stop heating and cool down.

[0055] Step s2: Lower the temperature of the material obtained in step s1 to 80℃, and slowly add propyltriethoxysilane isocyanate and diphenylmethane diisocyanate in portions. The total feeding time should be controlled within 30 minutes. After the addition is complete, keep the reaction at 80℃ for 2 hours.

[0056] Step s3: Cool the material obtained in step s2 to 65°C, then add the remaining raw materials, continue stirring at 200 r / min for 30 min, and then cool the material to 60°C to obtain the adhesive.

[0057] Preparation Example 2

[0058] A sealant adhesive differs from preparation example 1 in that the amounts of each raw material are different.

[0059] The preparation method of the adhesive includes the following steps:

[0060] Step s1: Add polyoxyethyl polyoxypropyl glycerol ether, polypropylene glycol, and bio-based polyol to a three-necked flask according to the formula. Turn on the stirrer and stir at a speed of 180 r / min. Turn on the electric furnace to heat to 115°C. When the temperature reaches 115°C, turn on the vacuum pump and dehydrate under vacuum of -0.1 MPa. When the moisture content of the dehydrated mixture is below 0.05%, stop heating and cool down.

[0061] Step s2: Lower the temperature of the material obtained in step s1 to 80℃, and slowly add propyltriethoxysilane isocyanate and diphenylmethane diisocyanate in portions. The total feeding time should be controlled within 30 minutes. After the addition is complete, keep the reaction at 80℃ for 2 hours.

[0062] Step s3: Cool the material obtained in step s2 to 65°C, then add the remaining raw materials, continue stirring at 180 r / min for 30 min, and then cool the material to 60°C to obtain the adhesive.

[0063] Preparation Example 3

[0064] A sealant adhesive differs from preparation example 1 in that the amounts of each raw material are different.

[0065] The preparation method of the adhesive includes the following steps:

[0066] Step s1: Add polyoxyethyl polyoxypropyl glycerol ether, polypropylene glycol, and bio-based polyol to a three-necked flask according to the formula. Turn on the stirrer and stir at a speed of 220 r / min. Turn on the electric furnace to heat to 110°C. When the temperature reaches 110°C, turn on the vacuum pump and dehydrate under vacuum of -0.09 MPa. When the moisture content of the dehydrated mixture is below 0.05%, stop heating and cool down.

[0067] Step s2: Lower the temperature of the material obtained in step s1 to 85℃, and slowly add propyltriethoxysilane isocyanate and diphenylmethane diisocyanate in portions. The total feeding time should be controlled within 30 minutes. After the addition is complete, keep the reaction at 85℃ for 1.5 hours.

[0068] Step s3: Cool the material obtained in step s2 to 70°C, then add the remaining raw materials, continue stirring at 220 r / min for 30 min, and then cool the material to 55°C to obtain the adhesive.

[0069] Preparation Example 4

[0070] A sealant adhesive, unlike Preparation Example 1, also includes a curing aid.

[0071] The curing aid is a mixture of trimethylolpropane triglycidyl ether and dodecyl polyoxyethylene ether in a 1:1 mass ratio.

[0072] Among them, trimethylolpropane triglycidyl ether is trimethylolpropane triglycidyl ether PB06397 from Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0073] Among them, dodecyl polyoxyethylene ether is the emulsifier OP-10 of Jinan Shengda Chemical Co., Ltd.

[0074] The curing aid is added in step s3.

[0075] Preparation Example 5

[0076] A sealant adhesive, unlike Preparation Example 1, also includes a curing aid.

[0077] The curing aid is a mixture of trimethylolpropane triglycidyl ether and dodecyl polyoxyethylene ether in a mass ratio of 1:1.37.

[0078] Among them, trimethylolpropane triglycidyl ether is trimethylolpropane triglycidyl ether PB06397 from Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0079] Among them, dodecyl polyoxyethylene ether is the emulsifier OP-10 of Jinan Shengda Chemical Co., Ltd.

[0080] The curing aid is added in step s3.

[0081] The amounts of each raw material used in the sealant for preparation examples 1-5 are shown in Table 1.

[0082] Table 1:

[0083]

[0084]

[0085] Preparation Example 6

[0086] A sealant adhesive, differing from Preparation Example 4, in which trimethylolpropane triglycidyl ether is replaced with ethylene glycol diglycidyl ether.

[0087] Preparation Example 7

[0088] A sealant adhesive, which differs from Preparation Example 4 in that dodecyl polyoxyethylene ether is replaced with octylphenol polyoxyethylene ether, i.e., emulsifier OP-6.

[0089] Comparative Preparation Example 1

[0090] A sealant adhesive, which differs from Preparation Example 1 in that the bio-based polyol is replaced in equal amounts with polypropylene glycol.

[0091] Example 1

[0092] An underwater curing polyurethane sealant includes an adhesive, dioctyl terephthalate, a wetting and dispersing agent, a dehydrating agent, a thixotropic agent, a filler, magnesium fluoride, carbon black, and an ultraviolet absorber.

[0093] The glue comes from Preparation Example 1.

[0094] Among them, dioctyl terephthalate is the dioctyl terephthalate (DOTP) produced by Shandong Lanfan Chemical Co., Ltd.

[0095] Among them, the wetting and dispersing agent is WL-201, a polyurethane wetting agent from Guangzhou Longchi New Material Technology Co., Ltd.

[0096] Among them, the dehydrating agent is a polyurethane-specific molecular sieve activation powder from Jiangxi Xintao Technology Co., Ltd.

[0097] The thixotropic agent is thixotropic powder B50 from Guangzhou Longchi New Material Technology Co., Ltd.

[0098] The filler used is calcium carbonate JY-250 from Lianzhou Jinyu Plastic Filler Co., Ltd.

[0099] Among them, magnesium fluoride is nano-magnesium fluoride from Hangzhou Zheming New Materials Co., Ltd.

[0100] Among them, the carbon black is Mitsubishi Chemical Corporation's carbon black MA100.

[0101] The ultraviolet absorber is BASF's UV-5411.

[0102] The preparation method of the underwater curing polyurethane sealant includes the following steps:

[0103] Step 1: Add dioctyl terephthalate and wetting and dispersing agent to a double planetary mixer according to the formula, turn on the mixer and stir at 70 r / min. Then slowly add plasticizer, wetting and dispersing agent, dehydrating agent, thixotropic agent, filler, magnesium fluoride, carbon black and ultraviolet absorber. The total feeding time should be controlled within 30 minutes. Then slowly stir for another 40 minutes.

[0104] Step 2: Add glue to the material obtained in Step 1, and then stir at 200 r / min until uniform. Next, degas under vacuum at -0.07 MPa for 40 min, and then degas under vacuum at -0.09 MPa for 20 min. Stop stirring to obtain underwater curing polyurethane sealant.

[0105] Example 2

[0106] An underwater curing polyurethane sealant differs from Example 1 in that the amounts of each raw material are different.

[0107] The glue comes from preparation example 2.

[0108] The preparation method of the underwater curing polyurethane sealant includes the following steps:

[0109] Step 1: Add dioctyl terephthalate and wetting and dispersing agent to a double planetary mixer according to the formula, start the mixer and stir at 60 r / min. Then slowly add plasticizer, wetting and dispersing agent, dehydrating agent, thixotropic agent, filler, magnesium fluoride, carbon black and ultraviolet absorber. The total feeding time should be controlled within 30 minutes. Then slowly stir for another 40 minutes.

[0110] Step 2: Add glue to the material obtained in Step 1, and then stir at 180 r / min until uniform. Next, degas under vacuum at -0.06 MPa for 40 min, and then degas under vacuum at -0.09 MPa for 20 min. Stop stirring to obtain underwater curing polyurethane sealant.

[0111] Example 3

[0112] An underwater curing polyurethane sealant differs from Example 1 in that the amounts of each raw material are different.

[0113] The glue used in this preparation comes from Example 3.

[0114] The preparation method of the underwater curing polyurethane sealant includes the following steps:

[0115] Step 1: Add dioctyl terephthalate and wetting and dispersing agent to a double planetary mixer according to the formula, start the mixer and stir at 80 r / min. Then slowly add plasticizer, wetting and dispersing agent, dehydrating agent, thixotropic agent, filler, magnesium fluoride, carbon black and ultraviolet absorber. The total feeding time should be controlled within 30 minutes, and then slowly stir for 40 minutes.

[0116] Step 2: Add glue to the material obtained in Step 1, and then stir at 220 r / min until uniform. Next, degas under vacuum at -0.07 MPa for 35 min, and then degas under vacuum at -0.095 MPa for 15 min. Stop stirring to obtain underwater curing polyurethane sealant.

[0117] The amounts of each raw material used in Examples 1-3 are shown in Table 2.

[0118] Table 2:

[0119]

[0120] Example 4

[0121] An underwater curing polyurethane sealant, which differs from Example 1 in that the adhesive is derived from Preparation Example 4.

[0122] Example 5

[0123] An underwater curing polyurethane sealant, which differs from Example 1 in that the adhesive is derived from Preparation Example 5.

[0124] Example 6

[0125] An underwater curing polyurethane sealant, which differs from Example 1 in that the adhesive is derived from Preparation Example 6.

[0126] Example 7

[0127] An underwater curing polyurethane sealant, which differs from Example 1 in that the adhesive is derived from Preparation Example 7.

[0128] Comparative Example 1

[0129] An underwater curing polyurethane sealant, which differs from Example 1 in that the adhesive is derived from Comparative Preparation Example 1.

[0130] Comparative Example 2

[0131] An underwater curing polyurethane sealant, which differs from Example 1 in that magnesium fluoride is replaced in equal amounts with nano-titanium dioxide.

[0132] Performance testing

[0133] The relevant properties of the underwater curing polyurethane sealants in the above embodiments and comparative examples were tested according to the test methods in JC / T 482-2022 "Polyurethane Building Sealants". The test results are shown in Table 3.

[0134] The percentage of bond strength retention is calculated using bond strength (dry) as a reference.

[0135] The ultraviolet irradiation conditions were: 50 W / m² energy, wavelength 300-400 nm, for 500 h.

[0136] Table 3:

[0137]

[0138] Specifically, based on the analysis of Examples 1-7 and Comparative Examples 1-2, it can be seen that the underwater curing polyurethane sealant of this application exhibits excellent performance in terms of underwater surface drying time, bonding strength, and resistance to salt spray and ultraviolet radiation.

[0139] Specifically, based on the analysis of Examples 1 and 4-7, the difference between Examples 4-5 and Example 1 lies in the addition of a curing aid, and the difference between Examples 6-7 and Example 4 lies in the replacement of trimethylolpropane triglycidyl ether and dodecyl polyoxyethylene ether in the curing aid, respectively. As can be seen from the comparison of the experimental data in Table 3, the curing aid composed of a mixture of trimethylolpropane triglycidyl ether and dodecyl polyoxyethylene ether has a good effect on improving the bonding strength and environmental resistance of underwater curing polyurethane sealant. It can be seen that the curing aid composed of a mixture of trimethylolpropane triglycidyl ether and dodecyl polyoxyethylene ether can better shorten the curing time and further improve the bonding strength after curing, thereby achieving better rapid curing and high bonding strength.

[0140] Specifically, based on the analysis of Example 1 and Comparative Example 1, the difference between Example 1 and Comparative Example 1 lies in the introduction of bio-based polyols. It can be seen that the further introduction of bio-based polyols on the basis of polyether polyols can not only improve the environmental performance of the sealant, but also significantly enhance the flexibility and bonding strength of the adhesive.

[0141] Specifically, based on the analysis of Example 1 and Comparative Example 2, the difference between Example 1 and Comparative Example 2 is that magnesium fluoride is replaced by an equal amount of nano-titanium dioxide. As can be seen from the comparison of the experimental data in Table 3, the introduction of magnesium fluoride improves the weather resistance and chemical corrosion resistance of the sealant, and also has a positive effect on improving the adhesion performance of the sealant.

[0142] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An underwater curing polyurethane sealant, characterized in that, The product comprises the following components by weight percentage: 28.41%-39.52% adhesive, 20%-25% dioctyl terephthalate, 0.1%-0.5% wetting and dispersing agent, 1%-2% dehydrating agent, 30%-40% thixotropic agent, 4%-6% filler, 1%-2% magnesium fluoride, 0.1%-1% carbon black, and 0.1%-0.3% ultraviolet absorber; The adhesive comprises the following raw materials in parts by weight: 9-10 parts polyoxyethyl polyoxypropyl glycerol ether, 12-15 parts polypropylene glycol, 0.1-0.5 parts vegetable oil polyol, 0.1-0.5 parts propyltriethoxysilane isocyanate, 0.1-0.2 parts γ-glycidyl etheroxypropyltrimethoxysilane, 3-5 parts diphenylmethane diisocyanate, 0.01-0.02 parts drying agent, 0.1-0.3 parts defoamer, 3-6 parts diluent, and 1-2 parts latent curing agent; The adhesive also includes 0.3-0.5 parts of a curing aid, which is a mixture of trimethylolpropane triglycidyl ether and dodecyl polyoxyethylene ether in a mass ratio of 1:(1-1.37).

2. The underwater curing polyurethane sealant according to claim 1, characterized in that, The adhesive comprises the following raw materials in parts by weight: 9.43 parts polyoxyethyl polyoxypropyl glycerol ether, 13.72 parts polypropylene glycol, 0.3 parts vegetable oil polyol, 0.3 parts propyltriethoxysilane isocyanate, 0.15 parts γ-glycidyl etheroxypropyltrimethoxysilane, 4.01 parts diphenylmethane diisocyanate, 0.012 parts drier, 0.2 parts defoamer, 4.32 parts diluent, 1.1 parts latent curing agent, and 0.37 parts curing aid.

3. The underwater curing polyurethane sealant according to any one of claims 1-2, characterized in that, The method for preparing the adhesive includes the following steps: Step s1: Mix polyoxyethyl polyoxypropyl glycerol ether, polypropylene glycol and vegetable oil polyol according to the formula, heat to 110-115℃, when the temperature reaches 110-115℃, vacuum dehydration is carried out, and when the moisture content of the dehydrated mixture is below 0.05%, heating is stopped and the temperature is lowered. Step s2: Lower the temperature of the material obtained in step s1 to 80-85℃, and slowly add propyltriethoxysilane isocyanate and diphenylmethane diisocyanate in portions. The total feeding time should be controlled within 30 minutes. After the addition is complete, keep the reaction at 80-85℃ for 1.5-2 hours. Step s3: Cool the material obtained in step s2 to 65-70℃, then add the remaining raw materials, continue stirring for 30 minutes, and then cool the material to 55-60℃ to obtain the adhesive.

4. The underwater curing polyurethane sealant according to claim 3, characterized in that, Step s1 involves stirring at a speed of 180-220 r / min and dehydrating under vacuum at a vacuum degree of -0.09~-0.1 MPa.

5. The underwater curing polyurethane sealant according to claim 1, characterized in that, The underwater curing polyurethane sealant comprises the following components by weight percentage: 33.912% adhesive, 22.028% dioctyl terephthalate, 0.33% wetting and dispersing agent, 1.38% dehydrating agent, 35.16% thixotropic agent, 5.16% filler, 1.32% magnesium fluoride, 0.5% carbon black, and 0.21% ultraviolet absorber.

6. A method for preparing an underwater curing polyurethane sealant as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Mix dioctyl terephthalate and wetting and dispersing agent according to the formula, then slowly add plasticizer, wetting and dispersing agent, dehydrating agent, thixotropic agent, filler, magnesium fluoride, carbon black and ultraviolet absorber. The total feeding time should be controlled within 30 minutes, and then slowly stir for 40 minutes. Step 2: Add glue to the material obtained in Step 1, then continue to stir until uniform. Next, perform vacuum degassing for 50-60 minutes, then stop stirring to obtain underwater curing polyurethane sealant.

7. The method for preparing an underwater curing polyurethane sealant according to claim 6, characterized in that, Step 1 involves stirring at a speed of 60-80 r / min, and Step 2 involves stirring at a speed of 180-220 r / min. Step 2 involves first performing vacuum degassing at -0.06~-0.07 MPa for 35-40 min, and then performing vacuum degassing at -0.095~-0.09 MPa for 15-20 min.

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