Preparation method of high-strength anticorrosive waterborne polyurethane material

Abstract

The application belongs to the technical field of polyurethane material processing, and particularly relates to a preparation method of high-strength corrosion-resistant waterborne polyurethane material. The unique polyol and isocyanate mixed system, and the use of compounded chain extender and crosslinking agent enable the material to form a high-strength molecular structure. Compared with ordinary waterborne polyurethane, the tensile strength and adhesion of the material are significantly improved, the material can withstand greater external force, and is suitable for protection in high-stress environment. The addition of modified biomass fiber and special corrosion inhibitor, and the dense crosslinking structure of the material itself effectively improve the corrosion resistance of the material. The salt spray test shows that the salt spray resistance time of the material is more than 1900h, which can significantly prolong the service life of the protected object. The whole preparation process uses water as the dispersion medium, does not use a large amount of organic solvent, meets the environmental protection requirements, and has good social and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane material processing technology, specifically relating to a method for preparing a high-strength, corrosion-resistant waterborne polyurethane material. Background Technology

[0002] Waterborne polyurethane (WPU) is a polyurethane dispersion system that uses water as the dispersion medium. Unlike traditional solvent-based polyurethane, WPU systems contain no organic solvents, are non-toxic, and do not pollute the environment. Therefore, it effectively reduces VOC emissions during use, meeting the requirements of green environmental protection. In addition to inheriting some of the excellent mechanical properties of solvent-based polyurethane, WPU also boasts advantages such as low cost, ease of transportation and storage, good low-temperature film-forming properties, relative ease of use, and good low-temperature resistance, abrasion resistance, and adhesion. Thanks to its superior performance, WPU has been widely used in various aspects of modern society, appearing in numerous scenarios. For various applications, WPU can be designed with different molecular structures and properties to meet specific needs. Common application areas include coatings, synthetic leather, adhesives, and fiber treatment.

[0003] Although waterborne polyurethane (WPU) has garnered significant attention in coating research and applications in recent years due to its controllable and tunable molecular structure, environmental friendliness, excellent mechanical properties, wear resistance, adhesion, and toughness, the presence of hydrophilic groups in its molecular chain structure compared to solvent-based polyurethanes leads to several drawbacks. These include poor water resistance, poor chemical resistance, low solids content, and slow film-forming speed, which severely limit the further development of WPU coatings. Therefore, necessary modifications to WPU are essential to improve its overall performance, broaden its application scope, enhance the strength and corrosion resistance of waterborne polyurethanes, and extend its service life. This has become an important direction for WPU-related research.

[0004] Based on this, we propose a method for preparing high-strength, corrosion-resistant waterborne polyurethane materials, hoping to address the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to address the existing problems by providing a method for preparing a high-strength, corrosion-resistant waterborne polyurethane material.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing a high-strength, corrosion-resistant waterborne polyurethane material includes the following steps:

[0008] S1. The vacuum-dehydrated polyol, modified biomass fiber, and nano titanium dioxide are placed together in a mixer and stirred at 2000~3000r / min for 30~40min to form a homogeneous suspension. The suspension is then added to a reaction vessel, heated to 60~70℃, and isocyanate is added. The mixture is stirred and reacted for 2~3h to obtain a prepolymer for later use.

[0009] S2. After dissolving the chain extender in water, add it to the prepolymer, cool it to 40~50℃, and stir to react for 2~3 hours.

[0010] S3. Add a crosslinking agent to the system after chain extension in step S2, heat to 60~70℃, and continue stirring for 1~2 hours to obtain a pre-emulsion.

[0011] S4. Add preservatives to the pre-emulsion, stir at 6000~8000r / min for 40~60min, add deionized water, continue stirring for 1~2h, then perform vacuum degassing treatment and adjust the pH to 7~8.

[0012] Further, the polyol mentioned in step S1 is a mixture of polycarbonate diol and polyether polyol, and the mass ratio of polycarbonate diol (number average molecular weight of 2000) to polyether polyol (number average molecular weight of 1800) is 1:0.5~1.

[0013] The temperature for vacuum dehydration is 110~120℃;

[0014] The amount of nano-titanium dioxide added is 0.6-1% of the mass of the polyol;

[0015] The isocyanate is hexamethylene diisocyanate;

[0016] The mass ratio of isocyanate to polyol is 1:1~2.

[0017] Furthermore, the amount of modified biomass fiber added in step S1 is 3-4% of the mass of the polyol;

[0018] The preparation of modified biomass fibers includes the following steps:

[0019] (1) After crushing bamboo fiber to 100-200 mesh, immerse it in phosphate buffer containing 0.5-0.6% cellulase, then place it in a shaker at 180-200 r / min and 38-40℃ for 2-3 hours and filter it. Then immerse it in the treatment agent, stir and mix it. Then treat it with ultraviolet light at 365nm and 50W for 20-30 minutes. Then add 3,4-dihydroxybenzaldehyde, heat it to 60-70℃ and react for 30-50 minutes. Then filter it, wash it with deionized water 3-5 times, and place it in a vacuum drying oven at 60-70℃ for 8-12 hours to obtain activated fiber.

[0020] (2) Add the above activated fiber to deionized water, with a mass-to-volume ratio of activated fiber to deionized water of 1g:9~10mL. Under ultrasonic conditions, stir at 800~1000r / min for 20~30min to form a fiber suspension.

[0021] (3) Add the fiber suspension to the reactor, and add 0.2 to 0.3 times the weight of activated fiber of glycidyl methacrylate, 0.1 to 0.16 times the weight of maleic anhydride, and 0.003 to 0.005 times the weight of azobisisobutyronitrile in sequence. Stir at 600 to 800 r / min for 10 to 20 min, then heat to 70 to 80 °C and continue stirring for 3 to 4 h.

[0022] (4) After the reaction is complete, filter the solution and wash it with anhydrous ethanol 3 to 5 times. Then place it in a vacuum drying oven and dry it at 60 to 70°C for 10 to 16 hours.

[0023] Further, the components and corresponding weight percentages of the treatment agent described in step (1) are 70-80% 1-butyl-3-methylimidazolium acetate ionic liquid, 0.6-0.9% nano titanium dioxide, and the remainder is deionized water.

[0024] Furthermore, the chain extender mentioned in step S2 is a compound of ethylenediamine and diethanolamine, with a molar ratio of ethylenediamine to diethanolamine of 1:1~2.

[0025] Furthermore, the crosslinking agent mentioned in step S3 is trimethylolpropane, and the mass fraction of the crosslinking agent in the system is 3~5%.

[0026] Furthermore, the amount of preservative used in step S4 is 2-3% of the total system mass;

[0027] The amount of deionized water used is 20-30% of the total system mass.

[0028] Furthermore, the preparation of the preservative includes the following steps:

[0029] 1) Add 2 mg / mL of dopamine hydrochloride, shake at 180~200 r / min and 40~46℃ for 5~6 h, then add zinc carbonate solution, react in a water bath at 60~70℃ for 2~3 h, filter, wash 2~3 times with deionized water, place in a vacuum drying oven and dry at 60~70℃ for 6~8 h to obtain pre-modified nano zinc oxide;

[0030] 2) After corona treatment, the pre-modified nano zinc oxide is immersed in phytic acid solution and ultrasonically treated for 30-40 minutes. Then, the temperature is raised to 60-70℃, epoxidized soybean oil is added, and the mixture is stirred at 100-200 r / min for 2-3 hours. After filtration and washing with deionized water 2-3 times, the mixture is placed in a vacuum drying oven and dried at 60-70℃ for 6-8 hours.

[0031] Furthermore, the voltage of the corona treatment described in step 2) is 10~15kV, and the treatment time is 30~60s.

[0032] The present invention has the following advantages over the prior art:

[0033] 1. This invention utilizes a unique polyol and isocyanate mixture system, along with the application of compound chain extenders and crosslinking agents, to create a high-strength molecular structure. Compared to ordinary waterborne polyurethane, the tensile strength and adhesion of the material are significantly improved, enabling it to withstand greater external forces and making it suitable for protection under high-stress environments. The addition of modified biomass fibers and specially formulated preservatives, along with the material's own dense crosslinked structure, effectively enhances its corrosion resistance. Salt spray tests show that the material of this invention has a salt spray resistance time exceeding 1900 hours, significantly extending the service life of the protected object. Furthermore, the entire preparation process uses water as the dispersion medium, avoiding the use of large amounts of organic solvents, thus meeting environmental protection requirements and demonstrating significant social and economic benefits.

[0034] 2. This invention combines enzymatic hydrolysis, photocatalytic oxidation, and dynamic covalent modification to activate bamboo fibers, achieving efficient and directional activation of hydroxyl groups in the bamboo fibers. A composite monomer of glycidyl methacrylate (GMA) and maleic anhydride (MAH) is used, and bifunctional groups are grafted onto the fiber surface via free radical polymerization. The epoxy groups in glycidyl methacrylate can react with the -NCO groups of the polyurethane prepolymer to form chemical crosslinking points. The anhydride groups of maleic anhydride react with the hydroxyl groups of the biomass fiber, enhancing grafting stability and providing polar sites for interpenetrating networks with the polyurethane matrix. Simultaneously, the abundant hydroxyl groups in the biomass fiber can undergo crosslinking reactions with the isocyanate groups in the polyurethane prepolymer, forming chemical crosslinking points and enhancing the three-dimensional network structure, which helps improve the mechanical strength and corrosion resistance of waterborne polyurethane materials. During the crosslinking stage, it works synergistically with the crosslinking agent to promote the formation of a ternary network of fiber-polyurethane-nanoparticles, further improving the overall performance of the waterborne polyurethane.

[0035] 3. In this invention, nano-zinc oxide is dispersed in a dopamine solution, forming a polydopamine coating layer on the surface of the nano-zinc oxide. This effectively enhances the dispersibility of the nano-zinc oxide and prevents its aggregation. Subsequent zinc carbonate treatment inhibits substrate corrosion. At this point, corona treatment is performed, using a high-voltage electric field to ionize the air and generate plasma (such as O).- OH - Free radicals are introduced into the ZnO surface, introducing oxygen-containing functional groups (such as -OH, -COOH), increasing the surface hydroxyl content, enhancing reactivity with the polyurethane prepolymer -NCO, reducing surface energy, decreasing nanoparticle aggregation, and improving dispersion stability in aqueous systems. Furthermore, by controlling the technical parameters of corona treatment, nanoscale roughness is improved, enhancing its mechanical interlocking with the matrix and promoting phytic acid loading. When used in waterborne polyurethanes, this allows for the release of PO4 when the coating is damaged. 3- The surface of the substrate is passivated, thereby further improving its corrosion resistance. After treatment with epoxidized soybean oil, the epoxy groups of the epoxidized soybean oil are ring-grafted with the amino groups of the polydopamine layer to form a flexible interface layer. The long chain of epoxidized soybean oil can further improve the compatibility of the preservative with polyurethane and enhance mechanical properties. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] A method for preparing a high-strength, corrosion-resistant waterborne polyurethane material includes the following steps:

[0039] S1. The vacuum-dehydrated polyol, modified biomass fiber, and nano titanium dioxide are placed together in a mixer and stirred at 2000 r / min for 30 min to form a homogeneous suspension. The suspension is then added to a reaction vessel, heated to 60℃, and hexamethylene diisocyanate is added. The mixture is stirred and reacted for 2 h to obtain a prepolymer for later use.

[0040] The polyol is a mixture of polycarbonate diol and polyether polyol, with a mass ratio of 1:0.5.

[0041] The temperature for vacuum dehydration is 110℃;

[0042] The amount of nano-titanium dioxide added is 0.6% of the mass of the polyol;

[0043] The mass ratio of isocyanate to polyol is 1:1;

[0044] The amount of modified biomass fiber added is 3% of the mass of the polyol;

[0045] The preparation of the modified biomass fiber includes the following steps:

[0046] (1) Bamboo fiber was crushed to 100 mesh and then immersed in phosphate buffer containing 0.5% cellulase. After that, it was shaken in a shaker at 180 r / min and 38℃ for 2 h and then filtered. After that, it was immersed in the treatment agent, stirred and mixed, and then treated with ultraviolet light at 365 nm and 50 W for 20 min. Then, 3,4-dihydroxybenzaldehyde was added, the temperature was raised to 60℃ and reacted for 30 min. After that, it was filtered, washed 3 times with deionized water, and then placed in a vacuum drying oven and dried at 60℃ for 8 h to obtain activated fiber. The components and corresponding weight percentages of the treatment agent were 70% 1-butyl-3-methylimidazolium acetate ionic liquid, 0.6% nano titanium dioxide, and the remainder was deionized water.

[0047] (2) Add the above activated fiber to deionized water, with a mass-to-volume ratio of activated fiber to deionized water of 1g:9mL. Under ultrasonic conditions, stir at 800r / min for 20min to form a fiber suspension.

[0048] (3) Add the fiber suspension to the reactor, and add 0.2 times the mass of activated fiber glycidyl methacrylate, 0.1 times the mass of maleic anhydride, and 0.003 times the mass of azobisisobutyronitrile in sequence. Stir at 600 r / min for 10 min, then heat to 70℃ and continue stirring for 3 h.

[0049] (4) After the reaction is complete, filter the solution, wash it three times with anhydrous ethanol, and then place it in a vacuum drying oven and dry it at 60°C for 10 hours.

[0050] S2. After dissolving ethylenediamine and diethanolamine in water at a molar ratio of 1:1, add them to the prepolymer, cool to 40°C, and stir to react for 2 hours.

[0051] S3. Add trimethylolpropane to the chain-extended system of step S2, heat to 60°C, and continue stirring for 1 hour to obtain a pre-emulsion.

[0052] The mass fraction of the crosslinking agent in the system is 3%;

[0053] S4. Add preservative to the pre-emulsion, stir at 6000r / min for 40min, add deionized water, continue stirring for 1h, then perform vacuum degassing and adjust the pH to 7.

[0054] The amount of preservative used is 2% of the total system mass;

[0055] The amount of deionized water used is 20% of the total system mass;

[0056] The preparation of the preservative includes the following steps:

[0057] 1) Add 2 mg / mL of dopamine hydrochloride, shake at 180 r / min and 40 °C for 5 h, then add zinc carbonate solution, react at 60 °C in a water bath for 2 h, filter, wash twice with deionized water, place in a vacuum drying oven and dry at 60 °C for 6 h to obtain pre-modified nano zinc oxide.

[0058] 2) After corona treatment, the pre-modified nano zinc oxide is immersed in phytic acid solution, ultrasonically treated for 30 min, then heated to 60℃, epoxidized soybean oil is added, stirred at 100 r / min for 2 h, filtered, washed twice with deionized water, and then placed in a vacuum drying oven and dried at 60℃ for 6 h.

[0059] The corona treatment voltage was 10kV, and the treatment time was 30s.

[0060] Example 2

[0061] A method for preparing a high-strength, corrosion-resistant waterborne polyurethane material includes the following steps:

[0062] S1. The vacuum-dehydrated polyol, modified biomass fiber, and nano-titanium dioxide are placed together in a mixer and stirred at 2500 r / min for 35 min to form a homogeneous suspension. The suspension is then added to a reaction vessel, heated to 65℃, and hexamethylene diisocyanate is added. The mixture is stirred and reacted for 2.5 h to obtain a prepolymer for later use.

[0063] The polyol is a mixture of polycarbonate diol and polyether polyol, with a mass ratio of 1:0.75.

[0064] The temperature for vacuum dehydration is 115℃;

[0065] The amount of nano-titanium dioxide added is 0.8% of the mass of the polyol;

[0066] The mass ratio of isocyanate to polyol is 1:1.5;

[0067] The modified biomass fiber was added at 3.5% of the mass of the polyol;

[0068] The preparation of the modified biomass fiber includes the following steps:

[0069] (1) Bamboo fiber was crushed to 150 mesh and then immersed in phosphate buffer containing 0.55% cellulase. After being shaken in a shaker at 190 r / min and 39℃ for 2.5 h, it was filtered and then immersed in the treatment agent. After stirring and mixing, it was treated with ultraviolet light at 365 nm and 50 W for 25 min. Then, 3,4-dihydroxybenzaldehyde was added, and the temperature was raised to 65℃ for 40 min. After filtration, it was washed 4 times with deionized water and then placed in a vacuum drying oven and dried at 65℃ for 10 h to obtain activated fiber. The components and corresponding weight percentages of the treatment agent were 75% 1-butyl-3-methylimidazolium acetate ionic liquid, 0.7% nano titanium dioxide, and the remainder was deionized water.

[0070] (2) Add the above activated fiber to deionized water, with a mass-to-volume ratio of activated fiber to deionized water of 1g:9.5mL. Under ultrasonic conditions, stir at 900r / min for 25min to form a fiber suspension.

[0071] (3) Add the fiber suspension to the reactor, and add glycidyl methacrylate (0.25 times the weight of activated fiber), maleic anhydride (0.13 times the weight of activated fiber), and azobisisobutyronitrile (0.004 times the weight of activated fiber) in sequence. Stir at 700 r / min for 15 min, then heat to 75℃ and continue stirring for 3.5 h.

[0072] (4) After the reaction is complete, filter the solution, wash it four times with anhydrous ethanol, and then place it in a vacuum drying oven and dry it at 65°C for 13 hours.

[0073] S2. After dissolving ethylenediamine and diethanolamine in water at a molar ratio of 1:1.5, add them to the prepolymer, cool to 45°C, and stir to react for 2.5 hours.

[0074] S3. Add trimethylolpropane to the chain-extended system of step S2, heat to 65°C, and continue stirring for 1.5 h to obtain a pre-emulsion.

[0075] The mass fraction of the crosslinking agent in the system is 4%;

[0076] S4. Add preservative to the pre-emulsion, stir at 7000 r / min for 50 min, add deionized water, continue stirring for 1.5 h, then perform vacuum degassing and adjust the pH to 7.5.

[0077] The amount of preservative used is 2.5% of the total system mass;

[0078] The amount of deionized water used is 25% of the total system mass;

[0079] The preparation of the preservative includes the following steps:

[0080] 1) Add 2 mg / mL of dopamine hydrochloride, shake at 190 r / min and 43 °C for 5.5 h, then add zinc carbonate solution, react at 65 °C in a water bath for 2.5 h, filter, wash twice with deionized water, place in a vacuum drying oven and dry at 65 °C for 7 h to obtain pre-modified nano zinc oxide.

[0081] 2) After corona treatment, the pre-modified nano zinc oxide is immersed in phytic acid solution and ultrasonically treated for 35 min. Then, the temperature is raised to 65℃, epoxidized soybean oil is added, and the mixture is stirred at 150 r / min for 2.5 h. After filtration and washing twice with deionized water, it is placed in a vacuum drying oven and dried at 65℃ for 7 h.

[0082] The corona treatment voltage was 12kV, and the treatment time was 45s.

[0083] Example 3

[0084] A method for preparing a high-strength, corrosion-resistant waterborne polyurethane material includes the following steps:

[0085] S1. The vacuum-dehydrated polyol, modified biomass fiber, and nano titanium dioxide are placed together in a mixer and stirred at 3000 r / min for 30-40 min to form a homogeneous suspension. The suspension is then added to a reaction vessel, heated to 70℃, and hexamethylene diisocyanate is added. The mixture is stirred and reacted for 3 h to obtain a prepolymer for later use.

[0086] The polyol is a mixture of polycarbonate diol and polyether polyol, with a mass ratio of 1:1 between the polycarbonate diol and the polyether polyol.

[0087] The temperature for vacuum dehydration is 120℃;

[0088] The amount of nano-titanium dioxide added is 1% of the mass of the polyol;

[0089] The mass ratio of isocyanate to polyol is 1:2;

[0090] The amount of modified biomass fiber added is 4% of the mass of the polyol;

[0091] The preparation of the modified biomass fiber includes the following steps:

[0092] (1) After pulverizing bamboo fiber to 200 mesh, it was immersed in phosphate buffer containing 0.6% cellulase, then placed in a shaker at 200 r / min and 40℃ for 3 h and filtered. Then it was immersed in the treatment agent, stirred and mixed, and treated with ultraviolet light at 365 nm and 50 W for 30 min. Then 3,4-dihydroxybenzaldehyde was added, the temperature was raised to 70℃ and reacted for 50 min. After filtration, it was washed with deionized water 3 to 5 times and placed in a vacuum drying oven and dried at 70℃ for 12 h to obtain activated fiber. The components and corresponding weight percentages in the treatment agent were 80% 1-butyl-3-methylimidazolium acetate ionic liquid, 0.9% nano titanium dioxide, and the remainder was deionized water.

[0093] (2) Add the above activated fiber to deionized water, with a mass-to-volume ratio of activated fiber to deionized water of 1g:10mL. Under ultrasonic conditions, stir at 1000r / min for 30min to form a fiber suspension.

[0094] (3) Add the fiber suspension to the reactor, and add 0.3 times the mass of activated fiber glycidyl methacrylate, 0.16 times the mass of maleic anhydride, and 0.005 times the mass of azobisisobutyronitrile in sequence. Stir at 800 r / min for 20 min, then heat to 80℃ and continue stirring for 4 h.

[0095] (4) After the reaction is complete, filter the solution and wash it 5 times with anhydrous ethanol. Then place it in a vacuum drying oven and dry it at 70°C for 16 hours.

[0096] S2. After dissolving ethylenediamine and diethanolamine in water at a molar ratio of 1:2, add them to the prepolymer, cool to 50°C, and stir to react for 3 hours.

[0097] S3. Add trimethylolpropane to the chain-extended system of step S2, heat to 70°C, and continue stirring for 2 hours to obtain a pre-emulsion.

[0098] The mass fraction of the crosslinking agent in the system is 5%;

[0099] S4. Add preservative to the pre-emulsion, stir at 8000r / min for 60min, add deionized water, continue stirring for 2h, then perform vacuum degassing and adjust the pH to 8.

[0100] The amount of preservative used is 3% of the total system mass;

[0101] The amount of deionized water used is 30% of the total system mass;

[0102] The preparation of the preservative includes the following steps:

[0103] 1) Add 2 mg / mL of dopamine hydrochloride, shake at 200 r / min and 46 °C for 6 h, then add zinc carbonate solution, react at 70 °C in a water bath for 3 h, filter, wash 3 times with deionized water, place in a vacuum drying oven and dry at 70 °C for 8 h to obtain pre-modified nano zinc oxide.

[0104] 2) After corona treatment, the pre-modified nano zinc oxide is immersed in phytic acid solution, ultrasonically treated for 40 min, then heated to 70℃, epoxidized soybean oil is added, stirred at 200 r / min for 3 h, filtered, washed 3 times with deionized water, and then placed in a vacuum drying oven and dried at 70℃ for 8 h.

[0105] The corona treatment voltage was 15kV, and the treatment time was 60s.

[0106] Comparative Example 1

[0107] Compared with Example 2, Comparative Example 1 replaces the modified biomass fiber in step S1 with untreated bamboo fiber, while the rest of the technical solutions are the same as those in Example 2.

[0108] Comparative Example 2

[0109] Compared with Example 2, Comparative Example 2 omits the modified biomass fiber in step S1, while the rest of the technical solutions are the same as those in Example 2.

[0110] Comparative Example 3

[0111] Compared with Example 2, Comparative Example 3 replaces the preservative in step S4 with untreated nano zinc oxide, while the rest of the technical solutions are the same as those in Example 2.

[0112] Performance testing

[0113] 1. Coating mechanical property testing

[0114] 1.1 Tensile strength test

[0115] Following the method in GB / T 528-2009, the waterborne polyurethane material coating samples were prepared into dumbbell-shaped specimens and tested using a universal testing machine at a tensile rate of 500 mm / min. The entire test was conducted at room temperature, and three sets of data were collected for each sample before processing. The formula for calculating the tensile strength is as follows:

[0116]

[0117] 1.2 Adhesion Test

[0118] Referring to GB / T 5210-2006, the adhesion of the coating was tested using a coating adhesion tester of model LRTC-10S. Each group of water-based polyurethane emulsions was coated onto the substrate surface. After complete curing to form a coating film, a circular forging die with a diameter of 5 cm was firmly bonded to the coating film using a specific composite adhesive, and allowed to stand for 12 hours. The adhesion tester was used to apply a tensile force to the coating film and the forging die until they separated. The ratio of the maximum tensile force Fmax to the area S of the circular forging die is the measured adhesion force, calculated using the following formula:

[0119]

[0120] The specific experimental comparison data are shown in Table 1 below.

[0121] Table 1

[0122] Adhesion (MPa) Tensile strength (MPa) Example 1 5.1 32.52 Example 2 5.6 33.56 Example 3 5.7 30.23 Comparative Example 1 4.5 27.25 Comparative Example 2 3.8 22.38 Comparative Example 3 5.1 39.25

[0123] As shown in Table 1 above, compared with Comparative Examples 1-3, the adhesion and tensile strength of the waterborne polyurethane materials prepared by the methods of Examples 1-3 of the present invention have been significantly improved.

[0124] 2. Salt spray resistance test

[0125] According to GB / T 10125-2012, the coating sample was fixed in the salt spray chamber at a 15° angle to the vertical direction. The sample was taken out every 240 hours, the surface was rinsed with deionized water, and the corrosion was observed after drying. The salt solution was 5% NaCl with a pH of 6.5~7.2.

[0126] The waterborne polyurethane coating of the present invention extends the salt spray resistance time to 1900-2100 hours, effectively improving the corrosion resistance of the material and extending the service life of the protected object.

[0127] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength, corrosion-resistant waterborne polyurethane material, characterized in that, Includes the following steps: S1. The vacuum-dehydrated polyol, modified biomass fiber, and nano titanium dioxide are placed together in a mixer and stirred at 2000~3000r / min for 30~40min to form a homogeneous suspension. The suspension is then added to a reaction vessel, heated to 60~70℃, and isocyanate is added. The mixture is stirred and reacted for 2~3h to obtain a prepolymer for later use. The modified biomass fiber is added at a rate of 3-4% of the mass of the polyol. The preparation of modified biomass fibers includes the following steps: (1) After crushing bamboo fiber to 100-200 mesh, immerse it in phosphate buffer containing 0.5-0.6% cellulase, then place it in a shaker at 180-200 r / min and 38-40℃ for 2-3 hours and filter it. Then immerse it in the treatment agent, stir and mix it. Then treat it with ultraviolet light at 365nm and 50W for 20-30 minutes. Then add 3,4-dihydroxybenzaldehyde, heat it to 60-70℃ and react for 30-50 minutes. Then filter it, wash it with deionized water 3-5 times, and place it in a vacuum drying oven at 60-70℃ for 8-12 hours to obtain activated fiber. The treatment agent comprises the following components and their corresponding weight percentages: 70-80% 1-butyl-3-methylimidazolium acetate ionic liquid, 0.6-0.9% nano-titanium dioxide, and the remainder is deionized water. (2) Add the above activated fiber to deionized water, with a mass-to-volume ratio of activated fiber to deionized water of 1g:9~10mL. Under ultrasonic conditions, stir at 800~1000r / min for 20~30min to form a fiber suspension. (3) Add the fiber suspension to the reactor, and add 0.2 to 0.3 times the weight of activated fiber of glycidyl methacrylate, 0.1 to 0.16 times the weight of maleic anhydride, and 0.003 to 0.005 times the weight of azobisisobutyronitrile in sequence. Stir at 600 to 800 r / min for 10 to 20 min, then heat to 70 to 80 °C and continue stirring for 3 to 4 h. (4) After the reaction is complete, filter the solution and wash it with anhydrous ethanol 3 to 5 times. Then place it in a vacuum drying oven and dry it at 60 to 70°C for 10 to 16 hours. S2. After dissolving the chain extender in water, add it to the prepolymer, cool it to 40~50℃, and stir to react for 2~3 hours. S3. Add a crosslinking agent to the system after chain extension in step S2, heat to 60~70℃, and continue stirring for 1~2 hours to obtain a pre-emulsion. S4. Add preservative to the pre-emulsion, stir at 6000~8000r / min for 40~60min, add deionized water, continue stirring for 1~2h, then perform vacuum degassing treatment and adjust the pH to 7~8. The preparation of the preservative includes the following steps: 1) Add nano zinc oxide to 2 mg / mL dopamine hydrochloride, shake at 180~200 r / min and 40~46℃ for 5~6 h, then add zinc carbonate solution, react in a water bath at 60~70℃ for 2~3 h, filter, wash 2~3 times with deionized water, place in a vacuum drying oven and dry at 60~70℃ for 6~8 h to obtain pre-modified nano zinc oxide; 2) After corona treatment, the pre-modified nano zinc oxide is immersed in phytic acid solution and ultrasonically treated for 30-40 minutes. Then, the temperature is raised to 60-70℃, epoxidized soybean oil is added, and the mixture is stirred at 100-200 r / min for 2-3 hours. After filtration and washing with deionized water 2-3 times, the mixture is placed in a vacuum drying oven and dried at 60-70℃ for 6-8 hours.

2. The method for preparing a high-strength, corrosion-resistant waterborne polyurethane material according to claim 1, characterized in that, The polyol mentioned in step S1 is a mixture of polycarbonate diol and polyether polyol, with a mass ratio of 1:0.5~1. The temperature for vacuum dehydration is 110~120℃; The amount of nano-titanium dioxide added is 0.6-1% of the mass of the polyol; The isocyanate is hexamethylene diisocyanate; The mass ratio of isocyanate to polyol is 1:1~2.

3. The method for preparing a high-strength, corrosion-resistant waterborne polyurethane material according to claim 1, characterized in that, The chain extender mentioned in step S2 is a compound of ethylenediamine and diethanolamine, with a molar ratio of ethylenediamine to diethanolamine of 1:1~2.

4. The method for preparing a high-strength, corrosion-resistant waterborne polyurethane material according to claim 1, characterized in that, The crosslinking agent mentioned in step S3 is trimethylolpropane, and the mass fraction of the crosslinking agent in the system is 3~5%.

5. The method for preparing a high-strength, corrosion-resistant waterborne polyurethane material according to claim 1, characterized in that, The amount of preservative used in step S4 is 2-3% of the total system mass; The amount of deionized water used is 20-30% of the total system mass.

6. The method for preparing a high-strength, corrosion-resistant waterborne polyurethane material according to claim 1, characterized in that, The voltage for the corona treatment described in step 2) is 10~15kV, and the treatment time is 30~60s.

7. A high-strength, corrosion-resistant waterborne polyurethane material, characterized in that, It is obtained by the preparation method described in any one of claims 1 to 6.