A high-strength corrosion-resistant coating for aircraft and preparation method thereof

Abstract

The present invention relates to the technical field of coatings, and in particular to a high-strength corrosion-resistant coating for aircraft and a preparation method thereof. First, waterborne polyurethane, titanium dioxide and modified graphene oxide are added to water, and then a dispersant is added and stirred evenly to obtain a premix, and then a defoamer, a curing agent and a light stabilizer are added to the premix, and stirring is continued to obtain the premix. The aircraft skin coating of the present invention has both good corrosion resistance and mechanical strength, and can adapt to harsh natural environments.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a high-strength corrosion-resistant coating for aircraft and a preparation method thereof. Background Art

[0002] Aircraft skin coatings are used for aircraft decoration, camouflage and corrosion protection of substrates, and are also the most widely used aviation coating products. The natural environment in which aircraft are located is complex and diverse. In harsh natural environments, especially in high humidity and high salt fog areas, aluminum alloys, aluminum-lithium alloys, stainless steel, etc. used to manufacture aircraft are extremely susceptible to corrosion. Corrosion can cause fatigue cracks in metal materials to initiate or grow, thereby reducing the strength of the material. Corrosion not only causes economic losses, but also brings serious safety problems. Therefore, corrosion problems have become a major factor in determining the structural integrity and life of aircraft. Coating is the main means of corrosion protection for skin and aircraft parts. Durable, long-lasting, high-performance coatings are the prerequisite for providing good corrosion protection.

[0003] Chinese patent publication number CN117343619 discloses a base color paint for aircraft skin and a preparation method thereof. The base color paint for aircraft skin is composed of a base material component A, a curing agent component B and a diluent component C. The components of the base material component A and their weight portions are: polyester resin, toughening resin, titanium dioxide, silicon dioxide, anti-sagging agent, wetting dispersant, drying agent, leveling agent, xylene, butyl acetate, propylene glycol methyl ether acetate. The base color paint has a high solid content during construction, and the paint film has the properties of strong hiding power, good medium resistance, excellent color retention and gloss retention, etc.

[0004] Chinese patent publication number CN104927591 discloses an aircraft skin finish paint and a preparation method thereof, wherein the formula is composed of the following components by weight: high hydroxyl content polyester resin, fluororesin, SCA modified polyester resin, silicone modified polyester resin, leveling agent, rheology control agent, catalyst, xylene, butyl acetate. The prepared paint has good high and low temperature resistance and impact resistance.

[0005] In harsh natural environments, aluminum alloys, aluminum-lithium alloys, stainless steel, etc. used to manufacture aircraft are extremely susceptible to corrosion. The aircraft skin coating in the above-mentioned patented technical solution is prone to corrosion under severe weather conditions, which in turn causes the aircraft skin coating to fall off, requiring frequent repairs of the aircraft skin coating. Summary of the invention

[0006] In order to overcome the above problems of the prior art, the present invention provides a high-strength corrosion-resistant coating for aircraft and a preparation method thereof. The aircraft skin coating of the present invention has both good corrosion resistance and mechanical strength and can adapt to harsh natural environments.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0008] A high-strength corrosion-resistant coating for aircraft, comprising the following components in parts by weight:

[0009] 80-100 parts of waterborne polyurethane resin, 50-60 parts of titanium dioxide, 20-30 parts of modified graphene oxide, 1-3 parts of defoaming agent, 1-3 parts of curing agent, 1-3 parts of dispersant, 1-3 parts of light stabilizer, and 90-120 parts of water.

[0010] In the technical solution of the present invention, waterborne polyurethane is used as the bonding component of the aircraft skin coating, and the coating does not contain organic solvents, which is green and environmentally friendly. Titanium dioxide is used as a filler for the coating. The sheet structure of graphene oxide can form a stacked maze effect in the coating, fill the holes in the coating, and block the contact between moisture, oxygen and corrosive media in the environment and the metal substrate. In addition, the graphene oxide sheet in the coating can block the micropores and defects formed in the coating during the curing process, increase the path for the corrosive medium to reach the metal substrate, and reduce the corrosion rate.

[0011] Preferably, the defoaming agent is polyoxyethylene ether.

[0012] Preferably, the curing agent is water-based polyisocyanate.

[0013] Preferably, the dispersant is polyacrylic acid.

[0014] Preferably, the method for preparing the modified graphene oxide comprises the following steps:

[0015] 1) Add graphene to concentrated sulfuric acid in an ice bath, stir evenly, then add potassium permanganate, heat to 70-75°C, add hydrogen peroxide for oxidation reaction, filter, wash and dry to obtain graphene oxide;

[0016] 2) adding graphene oxide to deionized water, dispersing it evenly by ultrasonic vibration to obtain a graphene oxide suspension, adding sodium hydroxide solution to the graphene oxide suspension, heating it at 60-65° C. for 20-30 min, centrifuging, washing and drying to obtain alkali-treated graphene oxide;

[0017] 3) adding the alkali-treated graphene oxide to a citric acid solution, heating at 70-80° C. for 1-2 hours, and obtaining wrinkled graphene oxide through centrifugal separation, washing and drying;

[0018] 4) adding silane coupling agent KH-560 to a mixed solution of ethanol and water, heating and stirring to obtain a hydrolyzate, adding wrinkled graphene oxide to the hydrolyzate, heating and stirring to react, centrifuging, washing and drying to obtain coupling agent modified wrinkled graphene oxide;

[0019] 5) adding hyperbranched polyethyleneimine into deionized water and stirring to dissolve to obtain a hyperbranched polyethyleneimine solution, adding the coupling agent-modified wrinkled graphene oxide into the hyperbranched polyethyleneimine solution, heating and stirring to react, filtering, washing and drying to obtain modified graphene oxide.

[0020] In the technical solution of the present invention, graphene oxide is added to the coating as described above to block the contact between moisture, oxygen and corrosive media in the environment and the metal substrate, so that the coating has a certain corrosion resistance. However, since graphene oxide is a planar structure, it will affect the barrier performance of graphene oxide to moisture and corrosive media. In order to further improve the corrosion resistance of the coating, the present invention performs surface modification treatment on graphene oxide, and treats the prepared graphene oxide with alkali solution and acid solution respectively to obtain graphene oxide with wrinkled surface. The wrinkled graphene oxide has a larger surface area and surface roughness than ordinary graphene oxide, and has better barrier performance to moisture and corrosive media, thereby further improving the corrosion resistance of the coating.

[0021] As mentioned above, the present invention performs acid-base treatment on graphene oxide to wrinkle the surface of graphene oxide and improve the barrier performance of graphene to moisture and corrosive media. However, it is found through testing that although wrinkled graphene oxide added to the coating can significantly improve the corrosion resistance of the coating, the mechanical strength of the coating is significantly reduced and the coating cracks during the curing process. In order to solve the above problems, the present invention further modifies the wrinkled graphene oxide, and grafts hyperbranched polyethyleneimine to the surface of the wrinkled graphene oxide through an epoxy silane coupling agent. The hyperbranched polyethyleneimine has a relatively large number of branched structures and is rich in amino groups. Its molecular chain is interspersed in the polyurethane resin, which plays a similar role in strengthening the skeleton. In addition, the residual hydroxyl groups of the polyurethane resin form hydrogen bonding forces with the amino groups on the hyperbranched polyethyleneimine, thereby improving the bonding force between graphene and polyurethane, thereby improving the impact strength of the coating, and obtaining a high-strength coating.

[0022] Preferably, the oxidation reaction time in step 1) is 1-3 hours.

[0023] Preferably, the concentration of the sodium hydroxide solution in step 2) is 0.1-0.5 wt %.

[0024] Preferably, the concentration of the citric acid solution in step 3) is 1-3 wt %.

[0025] Preferably, the reaction temperature in step 5) is 80°C and the reaction time is 2h;

[0026] The concentration of the hyperbranched polyethyleneimine solution is 0.8-2.3 wt %.

[0027] In the technical solution of the present invention, it is found through experiments that when the mass concentration of the hyperbranched polyethylene imine solution is higher than 0.8%, the surface of the wrinkled graphene oxide can be grafted with a sufficient amount of hyperbranched polyethylene imine, so that the coating has good mechanical strength. However, it was unexpectedly found during the experiment that when the mass concentration of the hyperbranched polyethylene imine solution exceeds 2.3%, the curing time of the coating suddenly increases significantly. This may be because the excessive amount of hyperbranched polyethylene imine grafted on the surface of the wrinkled graphene oxide has a hydrophilic effect on the large number of amino groups on the molecules, thereby hindering the evaporation of water in the coating. Therefore, the present invention simultaneously controls the mass concentration of the hyperbranched polyethylene imine solution to not exceed 2.3%.

[0028] A method for preparing a high-strength corrosion-resistant coating for aircraft comprises the following steps:

[0029] Adding waterborne polyurethane, titanium dioxide and modified graphene oxide into water, then adding a dispersant, and stirring evenly to obtain a premix;

[0030] Add defoamer, curing agent and light stabilizer to the premix and continue stirring to obtain the product.

[0031] The present invention has the following beneficial effects:

[0032] 1) Water-based polyurethane is used as the bonding component of aircraft skin coatings. The coatings do not contain organic solvents and are green and environmentally friendly;

[0033] 2) The prepared graphene oxide is treated with alkali solution and acid solution respectively to obtain graphene oxide with wrinkled surface. Compared with ordinary graphene oxide, wrinkled graphene oxide has a larger surface area and surface roughness, and has better barrier properties against moisture and corrosive media, thereby greatly improving the corrosion resistance of the coating;

[0034] 3) Hyperbranched polyethyleneimine is grafted onto the surface of wrinkled graphene oxide through epoxy silane coupling agent. Hyperbranched polyethyleneimine has a large number of branched structures and rich amino groups. Its molecular chain is interspersed in the polyurethane resin, playing a role similar to skeleton reinforcement. In addition, the residual hydroxyl groups of the polyurethane resin form hydrogen bonds with the amino groups on the hyperbranched polyethyleneimine, thereby increasing the bonding force between graphene and polyurethane, thereby increasing the strength of the coating and obtaining a high-strength coating. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0036] Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art.

[0037] In a specific embodiment, the light stabilizer used is Eversorb® AQ1 light stabilizer produced by Everlight Chemical. The molecular weight of the hyperbranched polyethyleneimine is 100000Da.

[0038] Example 1

[0039] A high-strength corrosion-resistant coating for aircraft, comprising the following components in parts by weight (see Table 1):

[0040] Table 1 Weight parts of the first type of high strength corrosion resistant coating for aircraft

[0041]

[0042] The preparation method of modified graphene oxide comprises the following steps:

[0043] 1) Add 3 g of graphene to 200 mL of concentrated sulfuric acid under ice bath conditions, stir evenly, then add 5 g of potassium permanganate, heat to 73 ° C, add 100 mL of 20% hydrogen peroxide for oxidation reaction for 2 h, filter, wash and dry to obtain graphene oxide;

[0044] 2) adding 2 g of graphene oxide to 100 mL of deionized water, dispersing the graphene oxide uniformly by ultrasonic oscillation to obtain a graphene oxide suspension, adding 100 mL of a 0.4 wt% sodium hydroxide solution to the graphene oxide suspension, heating at 63° C. for 25 min, centrifuging, washing and drying to obtain alkali-treated graphene oxide;

[0045] 3) adding 2 g of alkali-treated graphene oxide to 300 mL of a citric acid aqueous solution having a mass concentration of 2.5 wt%, heating at 75° C. for 1.5 h, and obtaining wrinkled graphene oxide after centrifugal separation, washing and drying;

[0046] 4) 100 mL of ethanol and 10 mL of water were mixed evenly, and then 1 g of silane coupling agent KH-560 was added to the mixed solution of ethanol and water, heated to 40°C, and stirred for 30 minutes to obtain a hydrolyzate; 2 g of wrinkled graphene oxide was added to the hydrolyzate, heated to 50°C, stirred for reaction for 2 hours, and centrifuged, washed and dried to obtain a coupling agent-modified wrinkled graphene oxide;

[0047] 5) Add hyperbranched polyethyleneimine into deionized water and stir to dissolve to prepare a hyperbranched polyethyleneimine solution with a mass concentration of 2.0wt%, add 2g of coupling agent-modified wrinkled graphene oxide into 500mL of the hyperbranched polyethyleneimine solution, heat to 80°C, stir to react for 2h, filter, wash and dry to obtain modified graphene oxide.

[0048] A method for preparing a high-strength corrosion-resistant coating for aircraft comprises the following steps:

[0049] Adding waterborne polyurethane, titanium dioxide and modified graphene oxide into water, then adding a dispersant, and stirring evenly to obtain a premix;

[0050] Add defoamer, curing agent and light stabilizer to the premix, and continue stirring at 800 r / min for 30 minutes to obtain the product.

[0051] Example 2

[0052] A high-strength corrosion-resistant coating for aircraft, comprising the following components in parts by weight (see Table 2):

[0053] Table 2 Weight parts of the second type of high strength corrosion resistant coating for aircraft

[0054]

[0055] The preparation method of modified graphene oxide comprises the following steps:

[0056] 1) Add 3 g of graphene to 200 mL of concentrated sulfuric acid under ice bath conditions, stir evenly, then add 5 g of potassium permanganate, heat to 73 ° C, add 100 mL of 20% hydrogen peroxide for oxidation reaction for 2 h, filter, wash and dry to obtain graphene oxide;

[0057] 2) adding 2 g of graphene oxide to 100 mL of deionized water, dispersing the graphene oxide uniformly by ultrasonic oscillation to obtain a graphene oxide suspension, adding 100 mL of a 0.3 wt% sodium hydroxide solution to the graphene oxide suspension, heating at 63° C. for 25 min, centrifuging, washing and drying to obtain alkali-treated graphene oxide;

[0058] 3) adding 2 g of alkali-treated graphene oxide to 300 mL of 1.5 wt% citric acid aqueous solution, heating at 75° C. for 1.5 h, and obtaining wrinkled graphene oxide after centrifugal separation, washing and drying;

[0059] 4) 100 mL of ethanol and 10 mL of water were mixed evenly, and then 1 g of silane coupling agent KH-560 was added to the mixed solution of ethanol and water, heated to 40°C, and stirred for 30 minutes to obtain a hydrolyzate; 2 g of wrinkled graphene oxide was added to the hydrolyzate, heated to 50°C, stirred for reaction for 2 hours, and centrifuged, washed and dried to obtain a coupling agent-modified wrinkled graphene oxide;

[0060] 5) Add hyperbranched polyethyleneimine into deionized water and stir to dissolve to prepare a hyperbranched polyethyleneimine solution with a mass concentration of 1.0 wt%, add 2 g of coupling agent-modified wrinkled graphene oxide into 500 mL of the hyperbranched polyethyleneimine solution, heat to 80° C., stir to react for 2 h, filter, wash and dry to obtain modified graphene oxide.

[0061] A method for preparing a high-strength corrosion-resistant coating for aircraft comprises the following steps:

[0062] Adding waterborne polyurethane, titanium dioxide and modified graphene oxide into water, then adding a dispersant, and stirring evenly to obtain a premix;

[0063] Add defoamer, curing agent and light stabilizer to the premix, and continue stirring at 800 r / min for 30 minutes to obtain the product.

[0064] Example 3

[0065] A high-strength corrosion-resistant coating for aircraft, comprising the following components in parts by weight (see Table 3):

[0066] Table 3 Weight parts of the third type of high strength corrosion resistant coating for aircraft

[0067]

[0068] The preparation method of modified graphene oxide comprises the following steps:

[0069] 1) Add 3 g of graphene to 200 mL of concentrated sulfuric acid under ice bath conditions, stir evenly, then add 5 g of potassium permanganate, heat to 73 ° C, add 100 mL of 20% hydrogen peroxide for oxidation reaction for 2 h, filter, wash and dry to obtain graphene oxide;

[0070] 2) adding 2 g of graphene oxide to 100 mL of deionized water, dispersing the graphene oxide uniformly by ultrasonic oscillation to obtain a graphene oxide suspension, adding 100 mL of a 0.3 wt% sodium hydroxide solution to the graphene oxide suspension, heating at 63° C. for 25 min, centrifuging, washing and drying to obtain alkali-treated graphene oxide;

[0071] 3) adding 2 g of alkali-treated graphene oxide to 300 mL of a 2 wt% citric acid aqueous solution, heating at 75° C. for 1.5 h, and obtaining wrinkled graphene oxide after centrifugal separation, washing and drying;

[0072] 4) 100 mL of ethanol and 10 mL of water were mixed evenly, and then 1 g of silane coupling agent KH-560 was added to the mixed solution of ethanol and water, heated to 40°C, and stirred for 30 minutes to obtain a hydrolyzate; 2 g of wrinkled graphene oxide was added to the hydrolyzate, heated to 50°C, stirred for reaction for 2 hours, and centrifuged, washed and dried to obtain a coupling agent-modified wrinkled graphene oxide;

[0073] 5) Add hyperbranched polyethyleneimine into deionized water and stir to dissolve to prepare a hyperbranched polyethyleneimine solution with a mass concentration of 1.5 wt%, add 2 g of coupling agent-modified wrinkled graphene oxide into 500 mL of the hyperbranched polyethyleneimine solution, heat to 80° C., stir to react for 2 h, filter, wash and dry to obtain modified graphene oxide.

[0074] A method for preparing a high-strength corrosion-resistant coating for aircraft comprises the following steps:

[0075] Adding waterborne polyurethane, titanium dioxide and modified graphene oxide into water, then adding a dispersant, and stirring evenly to obtain a premix;

[0076] Add defoamer, curing agent and light stabilizer to the premix, and continue stirring at 800 r / min for 30 minutes to obtain the product.

[0077] Example 4

[0078] A high-strength corrosion-resistant coating for aircraft, comprising the following components in parts by weight (see Table 4):

[0079] Table 4 Weight parts of the fourth type of high strength corrosion resistant coating for aircraft

[0080]

[0081] The preparation method of modified graphene oxide comprises the following steps:

[0082] 1) Add 3 g of graphene to 200 mL of concentrated sulfuric acid under ice bath conditions, stir evenly, then add 5 g of potassium permanganate, heat to 75 ° C, add 100 mL of 20% hydrogen peroxide for oxidation reaction for 3 hours, filter, wash and dry to obtain graphene oxide;

[0083] 2) adding 2 g of graphene oxide to 100 mL of deionized water, dispersing the graphene oxide uniformly by ultrasonic oscillation to obtain a graphene oxide suspension, adding 100 mL of a 0.5 wt% sodium hydroxide solution to the graphene oxide suspension, heating at 65° C. for 30 min, centrifuging, washing and drying to obtain alkali-treated graphene oxide;

[0084] 3) adding 2 g of alkali-treated graphene oxide to 300 mL of a 3 wt% citric acid aqueous solution, heating at 80° C. for 2 h, and obtaining wrinkled graphene oxide after centrifugal separation, washing and drying;

[0085] 4) 100 mL of ethanol and 10 mL of water were mixed evenly, and then 1 g of silane coupling agent KH-560 was added to the mixed solution of ethanol and water, heated to 40°C, and stirred for 30 minutes to obtain a hydrolyzate; 2 g of wrinkled graphene oxide was added to the hydrolyzate, heated to 50°C, stirred for reaction for 2 hours, and centrifuged, washed and dried to obtain a coupling agent-modified wrinkled graphene oxide;

[0086] 5) Add hyperbranched polyethyleneimine into deionized water and stir to dissolve to prepare a hyperbranched polyethyleneimine solution with a mass concentration of 2.3 wt%, add 2 g of coupling agent-modified wrinkled graphene oxide into 500 mL of the hyperbranched polyethyleneimine solution, heat to 80° C., stir to react for 2 h, and obtain modified graphene oxide after filtering, washing and drying.

[0087] A method for preparing a high-strength corrosion-resistant coating for aircraft comprises the following steps:

[0088] Adding waterborne polyurethane, titanium dioxide and modified graphene oxide into water, then adding a dispersant, and stirring evenly to obtain a premix;

[0089] Add defoamer, curing agent and light stabilizer to the premix, and continue stirring at 800 r / min for 30 minutes to obtain the product.

[0090] Example 5

[0091] A high-strength corrosion-resistant coating for aircraft, comprising the following components in parts by weight (see Table 5):

[0092] Table 5 Weight parts of the fifth type of high strength corrosion resistant coating for aircraft

[0093]

[0094] The preparation method of modified graphene oxide comprises the following steps:

[0095] 1) Add 3 g of graphene to 200 mL of concentrated sulfuric acid under ice bath conditions, stir evenly, then add 5 g of potassium permanganate, heat to 70 ° C, add 100 mL of 20% hydrogen peroxide for oxidation reaction for 1 hour, filter, wash and dry to obtain graphene oxide;

[0096] 2) adding 2 g of graphene oxide to 100 mL of deionized water, dispersing the graphene oxide uniformly by ultrasonic oscillation to obtain a graphene oxide suspension, adding 100 mL of a 0.1 wt% sodium hydroxide solution to the graphene oxide suspension, heating at 60° C. for 20 min, centrifuging, washing and drying to obtain alkali-treated graphene oxide;

[0097] 3) adding 2 g of alkali-treated graphene oxide to 300 mL of 1 wt% citric acid aqueous solution, heating at 70° C. for 1 h, and obtaining wrinkled graphene oxide after centrifugal separation, washing and drying;

[0098] 4) 100 mL of ethanol and 10 mL of water were mixed evenly, and then 1 g of silane coupling agent KH-560 was added to the mixed solution of ethanol and water, heated to 40°C, and stirred for 30 minutes to obtain a hydrolyzate; 2 g of wrinkled graphene oxide was added to the hydrolyzate, heated to 50°C, stirred for reaction for 2 hours, and centrifuged, washed and dried to obtain a coupling agent-modified wrinkled graphene oxide;

[0099] 5) Add hyperbranched polyethyleneimine into deionized water and stir to dissolve to prepare a hyperbranched polyethyleneimine solution with a mass concentration of 0.8 wt%, add 2 g of coupling agent-modified wrinkled graphene oxide into 500 mL of the hyperbranched polyethyleneimine solution, heat to 80° C., stir to react for 2 h, filter, wash and dry to obtain modified graphene oxide.

[0100] A method for preparing a high-strength corrosion-resistant coating for aircraft comprises the following steps:

[0101] Adding waterborne polyurethane, titanium dioxide and modified graphene oxide into water, then adding a dispersant, and stirring evenly to obtain a premix;

[0102] Add defoamer, curing agent and light stabilizer to the premix, and continue stirring at 800 r / min for 30 minutes to obtain the product.

[0103] Comparative Example 1:

[0104] The difference between Comparative Example 1 and Example 1 is:

[0105] The preparation process of modified graphene oxide only includes step 1), omitting other preparation steps.

[0106] The remaining steps are the same as those in Example 1.

[0107] Comparative Example 2:

[0108] The difference between Comparative Example 2 and Example 1 is:

[0109] Step 4) and step 5) are omitted in the preparation process of modified graphene oxide.

[0110] The remaining steps are the same as those in Example 1.

[0111] Comparative Example 3:

[0112] The difference between Comparative Example 3 and Example 5 is that:

[0113] In step 5) of the modified graphene oxide preparation process, the concentration of the prepared hyperbranched polyethyleneimine solution is 0.7 wt %.

[0114] The remaining steps are the same as those in Example 5.

[0115] Comparative Example 4:

[0116] The difference between Comparative Example 4 and Example 4 is that:

[0117] In step 5) of the modified graphene oxide preparation process, the concentration of the prepared hyperbranched polyethyleneimine solution is 2.4 wt %.

[0118] The remaining steps are the same as those in Example 4.

[0119] Comparative Example 5:

[0120] The difference between Comparative Example 5 and Example 4 is that:

[0121] In step 5) of the modified graphene oxide preparation process, the concentration of the prepared hyperbranched polyethyleneimine solution is 2.5 wt %.

[0122] The remaining steps are the same as those in Example 4.

[0123] Performance Testing:

[0124] Coating preparation: Prepare the coating in accordance with the provisions of GB / T1727-1992 "General Preparation of Paint Films". Test the surface drying and actual drying time of the coating at a temperature of 50°C and a relative humidity of 50%. After curing for 7 days at standard temperature and humidity, observe whether the coating surface cracks and test the various properties of the coating.

[0125] 1. Pencil hardness test: According to GB / T6739-1996 "Coating Hardness Pencil Determination Method", select 2B-6H Chinese pencils for testing on the pencil hardness test bench. Each sample is tested three times, and the lowest hardness is the final test result.

[0126] 2. Impact resistance test: According to GB / T1732-1993 "Determination of impact resistance of coating film", the test is carried out by using an impact tester to select different heights for impact test. Three points are selected for impact test on each sample. If one point fails, it is considered as failed. Select a suitable impact height and then conduct the test to obtain the final result.

[0127] 3. Adhesion test: Use a 10μm wire rod to evenly apply the paint on the steel plate, then put it into a 50℃ oven to dry the paint, cross the coating film, and then use transparent tape to peel off the coating film. The degree of damage is used to judge the adhesion level of the coating. According to the degree of damage, it can be divided into 0-5 grid levels, and 0-5 levels indicate that the adhesion gradually deteriorates.

[0128] 4. Corrosion resistance test: Take 5g of citric acid and add it into 1000mL of deionized water, stir and dissolve it to obtain an acidic solution. Soak the prepared coating in the acidic solution for 60 days, take it out and dry it, and observe whether there is any corrosion on the surface of the coating.

[0129] The above test data results are shown in Table 6:

[0130] Table 6 Test data results table

[0131]

[0132] By comparing the test data of Examples 1-5 with those of Comparative Example 1, it can be concluded that the corrosion resistance of the coatings prepared in Examples 1-5 is better than that of the coating in Comparative Example 1. This is because in Examples 1-5, the graphene oxide is treated with alkali solution and acid solution respectively to obtain graphene oxide with a wrinkled surface. The wrinkled graphene oxide has a larger surface area and surface roughness than ordinary graphene oxide, and has better barrier properties to moisture and corrosive media, thereby further improving the corrosion resistance of the coating.

[0133] By comparing the test data of Examples 1-5 with those of Comparative Example 2, it can be concluded that the impact resistance of the coatings prepared in Examples 1-5 is better than that of the coating in Comparative Example 2. This is because in Examples 1-5, hyperbranched polyethyleneimine is grafted to the surface of wrinkled graphene oxide through an epoxy silane coupling agent. Hyperbranched polyethyleneimine has a relatively large number of branched structures and is rich in amino groups. Its molecular chains are interspersed in the polyurethane resin, playing a role similar to skeleton reinforcement. In addition, the residual hydroxyl groups of the polyurethane resin form hydrogen bonding forces with the amino groups on the hyperbranched polyethyleneimine, thereby increasing the bonding force between graphene and polyurethane, thereby increasing the impact resistance of the coating.

[0134] By comparing the test data of Examples 1-5 with those of Comparative Example 3, it can be concluded that the impact strength of the coatings of Examples 1-5 is higher than that of Comparative Example 3. This is because the amount of hyperbranched polyethyleneimine grafted on the surface of the wrinkled graphene oxide in Comparative Example 3 is insufficient, and the skeleton reinforcement effect formed by the hyperbranched polyethyleneimine is weak, thereby reducing the impact strength of the coating.

[0135] By comparing the test data of Examples 1-5 with Comparative Examples 4-5, it can be found that the curing time of the coating of Examples 1-5 is significantly shorter than that of Comparative Examples 4 and 5. This may be because an excessive amount of hyperbranched polyethyleneimine is grafted onto the surface of the wrinkled graphene oxide, and a large number of amino groups on its molecules have a hydrophilic effect, thereby hindering the evaporation of water in the coating.

[0136] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A high-strength corrosion-resistant coating for aircraft, characterized in that: It comprises the following components by weight: 80-100 parts of waterborne polyurethane resin, 50-60 parts of titanium dioxide, 20-30 parts of modified graphene oxide, 1-3 parts of defoamer, 1-3 parts of curing agent, 1-3 parts of dispersant, 1-3 parts of light stabilizer, 90-120 parts of water; The preparation method of the modified graphene oxide comprises the following steps: 1) adding graphene to concentrated sulfuric acid under ice bath conditions, stirring evenly, then adding potassium permanganate, heating to 70-75° C., adding hydrogen peroxide for oxidation reaction, filtering, washing and drying to obtain graphene oxide; 2) adding graphene oxide to deionized water, dispersing it uniformly by ultrasonic vibration to obtain a graphene oxide suspension, adding a sodium hydroxide solution to the graphene oxide suspension, heating it at 60-65° C. for 20-30 min, centrifuging, washing and drying to obtain alkali-treated graphene oxide; 3) adding the alkali-treated graphene oxide to a citric acid solution, heating at 70-80° C. for 1-2 hours, and obtaining wrinkled graphene oxide through centrifugal separation, washing and drying; 4) adding silane coupling agent KH-560 to a mixed solution of ethanol and water, heating and stirring to obtain a hydrolyzate, adding wrinkled graphene oxide to the hydrolyzate, heating and stirring to react, centrifuging, washing and drying to obtain coupling agent-modified wrinkled graphene oxide; 5) adding hyperbranched polyethyleneimine into deionized water and stirring to dissolve to obtain a hyperbranched polyethyleneimine solution with a mass concentration of 0.8-2.3wt%, adding the coupling agent modified wrinkled graphene oxide into the hyperbranched polyethyleneimine solution, heating to 80°C and stirring to react for 2h, filtering, washing and drying to obtain modified graphene oxide.

2. The high-strength corrosion-resistant coating for aircraft according to claim 1, characterized in that: The defoaming agent is polyoxyethylene ether.

3. The high-strength corrosion-resistant coating for aircraft according to claim 1, characterized in that: The curing agent is water-based polyisocyanate.

4. The high-strength corrosion-resistant coating for aircraft according to claim 1, characterized in that: The dispersant is polyacrylic acid.

5. The high-strength corrosion-resistant coating for aircraft according to claim 1, characterized in that: The oxidation reaction time in step 1) is 1-3 hours.

6. The high-strength corrosion-resistant coating for aircraft according to claim 5, characterized in that: The concentration of the sodium hydroxide solution in step 2) is 0.1-0.5 wt %.

7. The high-strength corrosion-resistant coating for aircraft according to claim 5, characterized in that: The concentration of the citric acid solution in step 3) is 1-3 wt %.

8. A method for preparing a high-strength corrosion-resistant coating for aircraft according to any one of claims 1 to 7, characterized in that: The following steps are involved: Adding waterborne polyurethane, titanium dioxide and modified graphene oxide into water, then adding a dispersant, and stirring evenly to obtain a premix; Add defoamer, curing agent and light stabilizer to the premix and continue stirring to obtain the product.

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