A method for preparing an oil and wear resistant coating for an antenna tube surface

Abstract

The application provides a preparation method of an oil-resistant and wear-resistant coating for an antenna tube surface, and belongs to the technical field of composite coatings.The preparation method comprises the steps of spraying a primer, spraying a polyurea coating and post-treatment.The preparation primer step is mixing epoxy resin HY01A and epoxy resin HY01B to obtain the primer.The preparation method of the epoxy resin HY01A is adding bisphenol A type epoxy resin and propylene oxide butyl ether into a reaction kettle, stirring at 40-50 DEG C to obtain a homogeneous liquid, vacuum degassing to obtain the epoxy resin HY01A.The preparation method of the epoxy resin HY01B is stirring cashew nut shell oil modified amine in a mixed solvent, completely dissolving, adding kH550 silane coupling agent, stirring for 28-34 min to obtain the epoxy resin HY01B.The coating prepared by the preparation method has strong adhesion to the antenna tube substrate, excellent elastic performance, good oil resistance and wear resistance, and strong application in complex environments.

Description

Technical Field

[0001] This invention belongs to the field of composite coating technology, specifically relating to a method for preparing an oil-resistant and wear-resistant coating for the surface of an antenna tube. Background Technology

[0002] With the rapid development of wireless communication technology, antenna tubes, as core components of equipment such as radar, satellite communication, and 5G base stations, directly determine the stability of signal transmission and the service life of the equipment through their protective performance. However, traditional antenna tube protective materials have significant defects in complex environments such as high humidity, strong impact, chemical corrosion, and electrostatic interference, specifically in the following aspects:

[0003] (1) Insufficient adhesion between coating and substrate

[0004] Traditional protective coatings, such as single-layer epoxy resin or polyurethane, generally have low bonding strength with metal or composite material matrices; for example, under thermal cycling or mechanical vibration environments, the coating is prone to microcracks or even peeling.

[0005] Studies have shown that after 100 temperature cycles from -40°C to 80°C, the bonding strength of ordinary epoxy resin coatings decreases by more than 30%, leading to a significant increase in the risk of protective failure. In addition, the surface of antenna tubes often has complex structures such as grooves and welds, making it difficult for traditional spraying processes to achieve uniform coverage, which further weakens the overall protective effect of the coating.

[0006] (2) Insufficient elasticity and compressive strength

[0007] Antenna tubes are susceptible to dynamic impacts such as hail and gravel in outdoor environments, and it is difficult to balance the elastic modulus and hardness of pure polyurea or rubber-based coating materials in existing technologies.

[0008] For example, although pure polyurea coatings have high elasticity, they are prone to creep deformation in high-pressure environments such as deep sea or underground pipelines, resulting in uneven coating thickness; while high-hardness ceramic coatings have strong pressure resistance, they are brittle and prone to penetrating cracks under impact, making it difficult to meet the needs of 5G base station antenna tubes in typhoon-prone areas.

[0009] (3) Poor multi-functional integration

[0010] Existing protective materials are usually optimized for only a single performance, resulting in poor overall performance and significantly impacting their usability.

[0011] For example, hydrophobic coatings (such as silane-modified materials) can reduce rainwater adhesion, but they lack antistatic properties and are prone to signal interference due to static electricity accumulation; anti-corrosion coatings (such as zinc-rich epoxy) are prone to powdering under ultraviolet radiation and have poor compatibility with the upper functional coating.

[0012] (4) Process complexity and cost issues

[0013] In existing technologies, multiple layers of coatings are often required to achieve multi-functional protection. The typical method is to layer primer, intermediate layer and topcoat. However, the interlayer interface compatibility is poor and multiple curing processes are required, resulting in a long process cycle, with a total time of more than 72 hours and high energy consumption.

[0014] In summary, developing an oil-resistant and wear-resistant coating with high bonding strength and excellent elasticity has become a key issue that urgently needs to be addressed in the field of antenna tube technology. Summary of the Invention

[0015] To address the technical problems existing in the prior art, this invention provides a method for preparing an oil-resistant and wear-resistant coating on the surface of an antenna tube. The coating exhibits excellent uniformity, high bonding strength between the coating and the antenna tube, superior elasticity, and excellent oil and wear resistance, making it highly applicable in complex environments.

[0016] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0017] A method for preparing an oil-resistant and wear-resistant coating for the surface of an antenna tube includes spraying a primer, spraying a polyurea coating, and post-treatment steps, as detailed below:

[0018] 1. Apply primer

[0019] (1) Preparation of primer

[0020] Mix epoxy resin HY01A and epoxy resin HY01B, and stir for 5-8 minutes until a yellow, transparent and homogeneous state is obtained to obtain the primer.

[0021] The mass ratio of epoxy resin HY01A to epoxy resin HY01B is 1:2.8-3.2;

[0022] The preparation method of the epoxy resin HY01A is as follows: bisphenol A type epoxy resin and propylene oxide butyl ether are added to a reaction vessel, heated to 40-50℃, stirred at 200-300 rpm for 25-35 min to obtain a homogeneous liquid, and then vacuum degassing is performed, controlling the vacuum degree to be -0.09 to -0.07 MPa for 10-15 min, and stored below 30℃ to obtain epoxy resin HY01A;

[0023] The mass ratio of the bisphenol A type epoxy resin to the propylene oxide butyl ether is 1:0.15-0.20;

[0024] The preparation method of the epoxy resin HY01B is as follows: xylene and n-butanol are mixed and stirred evenly to obtain a mixed solvent; cashew nut shell oil modified amine is stirred in the mixed solvent at a stirring temperature of 36-46℃ and a stirring speed of 280-320rpm until completely dissolved; then bisphenol A type epoxy resin and kH550 silane coupling agent are added, and stirring is continued for 28-34min; after stirring, the mixture is cured for 22-24h to obtain epoxy resin HY01B.

[0025] The mass ratio of xylene to n-butanol is 7:2.8-3.2;

[0026] The mass ratio of the mixed solvent, cashew nut shell oil modified amine, bisphenol A type epoxy resin, and kH550 silane coupling agent is 30-50:8-12:100:1-3.

[0027] The method for preparing the cashew nut shell oil modified amine is as follows: cashew nut shell oil, formaldehyde solution and sodium hydroxide are mixed and then added to anhydrous ethanol. After stirring evenly, the temperature is raised to 65-68℃ and the reaction is stirred for 2.4-2.8h. 4.8-5.2wt% hydrochloric acid solution is added to adjust the pH to 7.2-7.5. Then ethylenediamine is added and the reaction is carried out in a closed container at 85-95℃ for 2-4h. After the reaction is completed, the mixture is cooled to room temperature, the aqueous phase is removed, and the organic phase is washed to obtain the cashew nut shell oil modified amine.

[0028] The mass-to-volume ratio of cashew shell oil, formaldehyde solution, sodium hydroxide, anhydrous ethanol, and ethylenediamine is 150-154g: 54-58mL: 8.4-8.7g: 96-100mL: 32-37g.

[0029] The formaldehyde solution has a mass concentration of 32-35%;

[0030] (2) Spraying

[0031] The primer is sprayed onto the outer surface of the antenna tube at a pressure of 0.15-0.25 MPa, a distance of 15-20 cm, and a thickness of 10-20 μm. After spraying, the tube is cured at room temperature for 24-30 hours to obtain the antenna tube with the primer.

[0032] 2. Apply polyurea coating

[0033] (1) Preparation of material A

[0034] The polyol is dehydrated under vacuum at a temperature of 110-120℃ and a vacuum degree of 0.04-0.06 kPa until the water content is less than 0.05 wt%. Then, it is added to the polyisocyanate under a nitrogen atmosphere and reacted at 60-80℃ for 1-2 hours to obtain material A.

[0035] The polyol is one of polypropylene glycol, polytetrahydrofuran ether glycol, or polyethylene adipate glycol, and the molecular weight of the polyol is 1000-2000.

[0036] The polyisocyanate is one of diphenylmethane diisocyanate (MDI) and toluene diisocyanate (TDI);

[0037] The mass ratio of the polyol to the polyisocyanate is 10:2.9-5.0;

[0038] (2) Preparation of material B

[0039] The composite filler and polyetheramine were premixed in a high-speed disperser at a speed of 2000-5000 rpm. After premixing, a chain extender was added under vacuum conditions, with the vacuum degree controlled at 0.05-0.10 bar. Then, ultrasonic treatment was performed at a frequency of 20-40 kHz, a duration of 34-40 min, and a power of 140-150 W. After ultrasonic treatment, the mixture was degassed under vacuum at 60-65℃ for 28-32 min to obtain material B.

[0040] The mass ratio of the composite filler, polyetheramine and chain extender is 25-30:60-70:5-10;

[0041] The polyetheramine is one of polyetheramines D230, D400, and T403;

[0042] The chain extender is at least one selected from ethylenediamine, 1,4-butanediamine, 3,5-dimethylthiotoluenediamine, and diethyltoluenediamine;

[0043] The composite filler is prepared by placing nano-silica in a tannic acid solution and stirring at a temperature of 52-56℃ for 1.3-1.8 hours. After stirring, the solid is filtered out and washed, then added to an ethanol solution. The temperature is increased to 60-64℃ at a rate of 1.2-1.8℃ / min. A silane coupling agent solution is added at a rate of 0.8-1.2 g / min. After addition, the mixture is kept warm and stirred for 2.0-2.5 hours. After filtration, washing, and drying, silane-treated nano-silica is obtained.

[0044] The particle size of the nano-silica is 20-50 nm;

[0045] The mass ratio of the nano-silica, tannic acid solution, ethanol solution, and silane coupling agent solution is 12-15:78-85:76-83:58-62;

[0046] The mass concentration of the tannic acid solution is 36-40 wt%.

[0047] The mass concentration of the ethanol solution is 27-32%;

[0048] The silane coupling agent solution is composed of a mixture of 27-32 wt% ethanol solution, kH540 silane coupling agent, and kH550 silane coupling agent, wherein the mass ratio of the 27-32 wt% ethanol solution, kH540 silane coupling agent, and kH550 silane coupling agent is 100:1.0-1.3:1.5-1.8.

[0049] Nano-silica was evenly dispersed in toluene, and then KH560 silane coupling agent was added for ball milling. The ball milling time was 45-50 min, the ball milling speed was 210-220 rpm, and the ball-to-material ratio was 3-5:1. After ball milling, the temperature was raised to 74-77℃ and the reaction was maintained for 3.4-4.0 h. After filtration, washing and drying, pretreated nano-silica was obtained.

[0050] The particle size of the nano-silica is 30-40 nm;

[0051] The mass ratio of the nano-silica, toluene, and kH560 silane coupling agent is 8-12:100:1.2-1.5;

[0052] Pretreated nano-silica and silane-treated nano-silica were added to anhydrous ethanol and ultrasonically dispersed at a power of 170-180W and a frequency of 52-58kHz for 43-47 min. Then, the temperature was increased to 56-60℃ at a rate of 0.4-0.6℃ / min and the reaction was maintained for 1.8-2.3 h. The solid was filtered out, washed, and dried to obtain the composite filler.

[0053] The mass ratio of anhydrous ethanol, pretreated nano-silica, and silane-treated nano-silica is 250:6.5-6.8:4.8-5.2.

[0054] (3) Dynamic spraying

[0055] Dynamic spraying is performed on the antenna tube after primer spraying. A spraying machine is used to spray material A and material B heated to 55-60℃ at 15-17MPa. During spraying, the antenna tube after primer spraying is placed in a rotating fixture, and the rotation speed is controlled at 3900-4100mm / min. The angle between the spray gun and the rotating fixture is adjusted to control the free end face at 40-50℃ and the groove surface at 85-95℃. The coating thickness of the antenna tube after primer spraying is controlled to be 2.0-3.0mm in the composite area and 5.0-6.0mm in the metal area, resulting in an antenna tube with a polyurea coating.

[0056] The mass ratio of material A to material B is 1:0.8-1.2.

[0057] 3. Post-processing

[0058] After the antenna tube is coated with polyurea, it is left to stand at room temperature for 1-2 hours, and then the temperature is raised to 65-75℃ and cured for 24-26 hours to obtain an oil-resistant and wear-resistant coating on the surface of the antenna tube.

[0059] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0060] This invention uses a specific two-component epoxy resin as a primer. The epoxy resin possesses good adhesion and chemical resistance. Epoxy propylene butyl ether reduces viscosity and promotes the primer's penetration into the antenna tube. Cashew nut shell oil-modified amines form a dense cross-linked network with the epoxy resin, and the long-chain alkyl groups reduce surface energy, enhancing adhesion to the polyurea coating. The silanol groups after KH550 hydrolysis can bond with the antenna tube substrate, while the amino groups at the other end can cross-link with the epoxy resin, enhancing interfacial bonding. Through specific formulation ratios and spraying parameters of the epoxy primer, high adhesion of the primer layer to metal and composite material substrates is ensured. This approach effectively addresses the risk of coating peeling, providing a stable interface for subsequent functional layers. The polyurea coating is obtained through a crosslinking reaction of isocyanate prepolymer, polyetheramine, and chain extender, forming a three-dimensional network structure that improves the coating's hardness, elasticity, and wear resistance, effectively resisting oil erosion. A composite filler, made from silica, is introduced into the polyurea coating. Specifically, the silica is first treated with tannic acid to increase the number of hydroxyl groups on its surface and enhance its surface activity. Then, KH540 and KH550 silane coupling agents are used to further treat the silica. Silane-treated nano-silica is obtained, enriching its surface with amino groups. These amino groups can bond with -NCO in component A and epoxy resin in component B. Furthermore, pretreated nano-silica is obtained by treating the silica with KH560 silane coupling agent, resulting in a higher concentration of epoxy groups on its surface. This improves the compatibility between the silica and component B. Finally, the silane-treated nano-silica reacts with the pretreated nano-silica to form a chemically bonded network, enhancing its compatibility and adhesion with the primer, component A, and component B. This ensures coating uniformity and effectively prevents coating peeling. This process enhances wear resistance and densifies the coating, preventing oil penetration. It significantly improves hardness while maintaining high elasticity, overcoming the inherent limitations of traditional materials that struggle to balance elastic modulus and pressure resistance. Finally, it assists in a dynamic spraying process. This process, combining rotating tooling and multi-angle spray gun control, achieves high-precision coverage of complex structures such as the free end and grooves of antenna tubes. This avoids the problems of missed coating or buildup that often occur in irregularly shaped areas with traditional processes. The post-treatment stage, through gradient curing and static stress release, forms a hydrophobic functional surface, exhibiting excellent weather resistance and long lifespan in harsh environments.

[0061] 2. The antenna tube obtained by this invention has an oil-resistant and wear-resistant coating on its surface, good hydrophobicity, a contact angle of 117-125°, a Shore hardness of 70-75, and a fracture toughness of 2.15-2.46 MPa·m. 1 / 2 ;

[0062] 3. The oil-resistant and wear-resistant coating on the surface of the antenna tube obtained by the present invention has a bonding strength of 16.7-18.0 MPa with the composite material area of ​​the antenna tube and a bonding strength of 21.9-24.1 MPa with the metal area of ​​the antenna tube;

[0063] 4. The oil-resistant and wear-resistant coating on the surface of the antenna tube prepared by this invention is subjected to a friction test using a friction loss testing machine. Before the friction test, the coating sample is cleaned and dried, and its weight is recorded as m1. After the friction test, the coating sample is cleaned and dried, and its weight is recorded as m2. The wear rate is calculated as (m1-m2) / m1×100%. During the friction test, the test temperature is 26℃, the relative humidity is 62%, the friction speed is 250rpm, the friction test force is 520N, the friction test time is 60min, and the wear rate is 0.084-0.092%.

[0064] 5. The antenna tube surface coated with an oil-resistant and wear-resistant coating obtained by this invention is placed in a sealed container and impregnated with hydraulic oil. The hydraulic oil completely submerges the wear-resistant and wear-resistant coating on the antenna tube surface. The impregnation pressure is 8.0 MPa, and the impregnation time is 168 h. The bonding strength with the antenna tube composite material area is measured to be 15.9-17.2 MPa, the bonding strength with the antenna tube metal area is 20.9-23.2 MPa, and the fracture toughness is 2.06-2.41 MPa·m. 1 / 2 ;

[0065] 6. The surface of the antenna tube prepared by this invention is subjected to ultraviolet irradiation with an oil-resistant and wear-resistant coating, and the ultraviolet intensity is controlled at 120 W / cm². 2 The irradiation time was 168 hours. The bond strength with the antenna tube composite region was measured again to be 15.5-16.0 MPa, the bond strength with the antenna tube metal region was 20.4-22.7 MPa, and the fracture toughness was 2.04-2.39 MPa·m. 1 / 2 . Detailed Implementation

[0066] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described.

[0067] Example 1

[0068] 1. Apply primer

[0069] (1) Preparation of primer

[0070] Mix epoxy resin HY01A and epoxy resin HY01B, and stir for 8 minutes until a yellow, transparent, and homogeneous state is obtained to obtain the primer.

[0071] The mass ratio of epoxy resin HY01A to epoxy resin HY01B is 1:3.2;

[0072] The preparation method of the epoxy resin HY01A is as follows: bisphenol A type epoxy resin and propylene oxide butyl ether are added to a reaction vessel, heated to 50°C, stirred at 300 rpm for 35 min to obtain a homogeneous liquid, and then vacuum degassing is performed, with the vacuum degree controlled at -0.07 MPa for 15 min, and stored below 30°C to obtain epoxy resin HY01A.

[0073] The mass ratio of the bisphenol A type epoxy resin to the propylene oxide butyl ether is 1:0.20;

[0074] The preparation method of epoxy resin HY01B is as follows: xylene and n-butanol are mixed and stirred evenly to obtain a mixed solvent; cashew nut shell oil modified amine is stirred in the mixed solvent at a stirring temperature of 46°C and a stirring speed of 320 rpm until completely dissolved; then bisphenol A type epoxy resin and kH550 silane coupling agent are added, and stirring is continued for 34 min; after stirring, it is cured for 24 h to obtain epoxy resin HY01B.

[0075] The mass ratio of xylene to n-butanol is 7:3.2;

[0076] The mass ratio of the mixed solvent, cashew nut shell oil modified amine, bisphenol A epoxy resin, and kH550 silane coupling agent is 50:8:100:3.

[0077] The method for preparing the cashew nut shell oil modified amine is as follows: 154g of cashew nut shell oil, 58mL of 35wt% formaldehyde solution and 8.7g of sodium hydroxide are mixed and then added to 100mL of anhydrous ethanol. After stirring evenly, the temperature is raised to 68℃ and the reaction is stirred for 2.8h. 5.2wt% hydrochloric acid solution is added to adjust the pH to 7.5, and then 37g of ethylenediamine is added. The reaction is carried out in a sealed container at 95℃ for 4h. After the reaction is completed, the mixture is cooled to room temperature, the aqueous phase is removed, and the organic phase is washed to obtain the cashew nut shell oil modified amine.

[0078] (2) Spraying

[0079] The primer was sprayed onto the outer surface of the antenna tube at a pressure of 0.25 MPa, a distance of 20 cm, and a thickness of 20 μm. After spraying, the tube was cured at room temperature for 30 h to obtain the antenna tube with the primer.

[0080] 2. Apply polyurea coating

[0081] (1) Preparation of material A

[0082] 10g of polyethylene adipate diol was dehydrated under vacuum at a temperature of 120℃ and a vacuum degree of 0.06kPa until the moisture content was less than 0.05wt%. Then, it was added to 4.7g of toluene diisocyanate (TDI) under a nitrogen atmosphere and reacted at 80℃ for 1.0h to obtain material A.

[0083] The molecular weight of the polyethylene adipate diol is 1000;

[0084] (2) Preparation of material B

[0085] The composite filler and polyetheramine were premixed in a high-speed disperser at a speed of 5000 rpm. After premixing, a chain extender was added under vacuum conditions, with the vacuum degree controlled at 0.10 bar. Then, ultrasonic treatment was performed at a frequency of 40 kHz, a duration of 40 min, and a power of 150 W. After ultrasonic treatment, the mixture was degassed under vacuum at 65°C for 32 min to obtain material B.

[0086] The mass ratio of the composite filler, polyetheramine and chain extender is 30:70:10;

[0087] The polyetheramine is polyetheramine T403;

[0088] The chain extender is a mixture of 1,4-butanediamine and diethyltoluenediamine, wherein the mass ratio of 1,4-butanediamine to diethyltoluenediamine is 1.3:1;

[0089] The composite filler is prepared by placing 15g of nano-silica in 85g of tannic acid solution and stirring at 56℃ for 1.8h. After stirring, the solid is filtered out and washed, then added to 83g of 32wt% ethanol solution. The temperature is increased to 64℃ at a rate of 1.8℃ / min, and 62g of silane coupling agent solution is added at a rate of 1.2g / min. After addition, the mixture is kept warm and stirred for 2.5h. After filtration, washing and drying, silane-treated nano-silica is obtained.

[0090] The particle size of the nano-silica is 520 nm;

[0091] The mass concentration of the tannic acid solution is 40 wt%.

[0092] The silane coupling agent solution is composed of a 32wt% ethanol solution, kH540 silane coupling agent, and kH550 silane coupling agent, wherein the mass ratio of the 32wt% ethanol solution, kH540 silane coupling agent, and kH550 silane coupling agent is 100:1.3:1.8.

[0093] 12g of nano-silica was dispersed evenly in 100g of toluene, and 1.5g of kH560 silane coupling agent was added for ball milling. The ball milling time was 50min, the ball milling speed was 220rpm, and the ball-to-material ratio was 53:1. After ball milling, the temperature was raised to 77℃ and the reaction was maintained for 4.0h. After filtration, washing and drying, pretreated nano-silica was obtained.

[0094] The particle size of the nano-silica is 40 nm;

[0095] 6.8g of pretreated nano-silica and 5.2g of silane-treated nano-silica were added to 250g of anhydrous ethanol and ultrasonically dispersed at a power of 180W and a frequency of 58kHz for 47min. Then the temperature was increased to 60℃ at a rate of 0.6℃ / min and the reaction was maintained for 2.3h. The solid was filtered out, washed and dried to obtain the composite filler.

[0096] (3) Dynamic spraying

[0097] Dynamic spraying was performed on the antenna tube after the primer was applied. A spraying machine was used to spray materials A and B heated to 60℃ at 17MPa. During spraying, the antenna tube after the primer was applied was placed in a rotating fixture, and the rotation speed was controlled at 4100mm / min. The angle between the spray gun and the rotating fixture was adjusted to control the free end face at 50℃ and the groove surface at 95℃. The coating thickness of the antenna tube after the primer was controlled to be 3.0mm in the composite material area and 6.0mm in the metal area, resulting in an antenna tube with a polyurea coating.

[0098] The mass ratio of material A to material B is 1:1.2.

[0099] 3. Post-processing

[0100] After the antenna tube with the sprayed polyurea coating was left to stand at room temperature for 2 hours, the temperature was then increased to 75°C and cured for 26 hours to obtain an oil-resistant and wear-resistant coating on the surface of the antenna tube.

[0101] Example 2

[0102] 1. Apply primer

[0103] (1) Preparation of primer

[0104] Mix epoxy resin HY01A and epoxy resin HY01B, and stir for 5 minutes until a yellow, transparent and homogeneous state is obtained to obtain the primer.

[0105] The mass ratio of epoxy resin HY01A to epoxy resin HY01B is 1:2.8;

[0106] The preparation method of the epoxy resin HY01A is as follows: bisphenol A type epoxy resin and propylene oxide butyl ether are added to a reaction vessel, heated to 40°C, stirred at 200 rpm for 25 min to obtain a homogeneous liquid, and then vacuum degassing is performed, with the vacuum degree controlled at -0.09 MPa for 13 min, and stored below 30°C to obtain epoxy resin HY01A.

[0107] The mass ratio of the bisphenol A type epoxy resin to the propylene oxide butyl ether is 1:0.15;

[0108] The preparation method of the epoxy resin HY01B is as follows: xylene and n-butanol are mixed and stirred evenly to obtain a mixed solvent; cashew nut shell oil modified amine is stirred in the mixed solvent at a stirring temperature of 36°C and a stirring speed of 280 rpm until completely dissolved; then bisphenol A type epoxy resin and kH550 silane coupling agent are added, and stirring is continued for 28 min; after stirring, the mixture is cured for 22 h to obtain epoxy resin HY01B.

[0109] The mass ratio of xylene to n-butanol is 7:2.8;

[0110] The mass ratio of the mixed solvent, cashew nut shell oil modified amine, bisphenol A epoxy resin, and kH550 silane coupling agent is 30:12:100:1.

[0111] The method for preparing the cashew nut shell oil modified amine is as follows: 150g cashew nut shell oil, 54mL 32wt% formaldehyde solution and 8.4g sodium hydroxide are mixed and then added to 96mL anhydrous ethanol. After stirring evenly, the temperature is raised to 65℃ and stirred for 2.4h. 4.8wt% hydrochloric acid solution is added to adjust the pH to 7.2. Then 32g ethylenediamine is added and the reaction is carried out in a sealed container at 85℃ for 2h. After the reaction is completed, the mixture is cooled to room temperature, the aqueous phase is removed, and the organic phase is washed to obtain the cashew nut shell oil modified amine.

[0112] (2) Spraying

[0113] The primer was sprayed onto the outer surface of the antenna tube at a pressure of 0.15 MPa, a distance of 15 cm, and a thickness of 10 μm. After spraying, the tube was cured at room temperature for 24 hours to obtain the antenna tube with the primer.

[0114] 2. Apply polyurea coating

[0115] (1) Preparation of material A

[0116] 10g of polytetrahydrofuran ether diol was dehydrated under vacuum at a temperature of 110℃ and a vacuum degree of 0.04kPa until the moisture content was less than 0.05wt%. Then, it was added to 5.0g of diphenylmethane diisocyanate (MDI) under a nitrogen atmosphere and reacted at 60℃ for 2.0h to obtain material A.

[0117] The molecular weight of the polytetrahydrofuran ether diol is 1000;

[0118] (2) Preparation of material B

[0119] The composite filler and polyetheramine were premixed in a high-speed disperser at a speed of 2000 rpm. After premixing, a chain extender was added under vacuum conditions, with the vacuum degree controlled at 0.05 bar. Then, ultrasonic treatment was performed at a frequency of 20 kHz, a duration of 34 min, and a power of 140 W. After ultrasonic treatment, the mixture was degassed under vacuum at 60 °C for 28 min to obtain material B.

[0120] The mass ratio of the composite filler, polyetheramine and chain extender is 25:60:5;

[0121] The polyetheramine is polyetheramine D400;

[0122] The chain extender is a mixture of ethylenediamine and 1,4-butanediamine, wherein the mass ratio of ethylenediamine to 1,4-butanediamine is 1:1;

[0123] The composite filler is prepared by placing 12g of nano-silica in 78g of tannic acid solution and stirring at 52℃ for 1.3h. After stirring, the solid is filtered out and washed, then added to 76g of 27wt% ethanol solution. The temperature is increased to 60℃ at a rate of 1.2℃ / min, and 58g of silane coupling agent solution is added at a rate of 0.8g / min. After addition, the mixture is kept warm and stirred for 2.0h. After filtration, washing and drying, silane-treated nano-silica is obtained.

[0124] The particle size of the nano-silica is 20 nm;

[0125] The mass concentration of the tannic acid solution is 36 wt%.

[0126] The silane coupling agent solution is composed of a mixture of 27wt% ethanol solution, kH540 silane coupling agent, and kH550 silane coupling agent, wherein the mass ratio of the 27wt% ethanol solution, kH540 silane coupling agent, and kH550 silane coupling agent is 100:1.0:1.5.

[0127] 8g of nano-silica was dispersed evenly in 100g of toluene, and 1.2g of kH560 silane coupling agent was added for ball milling. The ball milling time was 45min, the ball milling speed was 210rpm, and the ball-to-material ratio was 3:1. After ball milling, the temperature was raised to 74℃ and kept at that temperature for 3.4h. After filtration, washing and drying, pretreated nano-silica was obtained.

[0128] The particle size of the nano-silica is 30 nm;

[0129] 6.5g of pretreated nano-silica and 4.8g of silane-treated nano-silica were added to 250g of anhydrous ethanol and ultrasonically dispersed at a power of 170W and a frequency of 52kHz for 43min. Then the temperature was increased to 56℃ at a rate of 0.4℃ / min and the reaction was maintained for 1.8h. The solid was filtered out, washed and dried to obtain the composite filler.

[0130] (3) Dynamic spraying

[0131] Dynamic spraying was performed on the antenna tube after the primer was applied. A spraying machine was used to spray materials A and B heated to 55℃ at 15MPa. During spraying, the antenna tube after the primer was applied was placed in a rotating fixture, and the rotation speed was controlled at 3900mm / min. The angle between the spray gun and the rotating fixture was adjusted to control the free end face at 40℃ and the groove surface at 85℃. The coating thickness of the antenna tube after the primer was controlled to be 2.0mm in the composite area and 5.0mm in the metal area, resulting in an antenna tube with a polyurea coating.

[0132] The mass ratio of material A to material B is 1:0.8.

[0133] 3. Post-processing

[0134] After the antenna tube with the sprayed polyurea coating is left to stand at room temperature for 1 hour, the temperature is then increased to 65°C and cured for 24 hours to obtain an oil-resistant and wear-resistant coating on the surface of the antenna tube.

[0135] Example 3

[0136] 1. Apply primer

[0137] (1) Preparation of primer

[0138] Mix epoxy resin HY01A and epoxy resin HY01B, and stir for 7 minutes until a yellow, transparent, and homogeneous state is obtained to obtain the primer.

[0139] The mass ratio of epoxy resin HY01A to epoxy resin HY01B is 1:3.0;

[0140] The preparation method of the epoxy resin HY01A is as follows: bisphenol A type epoxy resin and propylene oxide butyl ether are added to a reaction vessel, heated to 45°C, stirred at 260 rpm for 30 min to obtain a homogeneous liquid, and then vacuum degassing is performed, with the vacuum degree controlled at -0.08 MPa for 10 min, and stored below 30°C to obtain epoxy resin HY01A.

[0141] The mass ratio of the bisphenol A type epoxy resin to the propylene oxide butyl ether is 1:0.17;

[0142] The preparation method of epoxy resin HY01B is as follows: xylene and n-butanol are mixed and stirred evenly to obtain a mixed solvent; cashew nut shell oil modified amine is stirred in the mixed solvent at a stirring temperature of 40°C and a stirring speed of 300 rpm until completely dissolved; then bisphenol A type epoxy resin and kH550 silane coupling agent are added, and stirring is continued for 30 min; after stirring, the mixture is cured for 23 h to obtain epoxy resin HY01B.

[0143] The mass ratio of xylene to n-butanol is 7:3;

[0144] The mass ratio of the mixed solvent, cashew nut shell oil modified amine, bisphenol A epoxy resin, and kH550 silane coupling agent is 40:10:100:2.

[0145] The method for preparing the cashew nut shell oil modified amine is as follows: 152g of cashew nut shell oil, 56mL of 33wt% formaldehyde solution and 8.5g of sodium hydroxide are mixed and then added to 98mL of anhydrous ethanol. After stirring evenly, the temperature is raised to 66℃ and the reaction is stirred for 2.6h. 5.0wt% hydrochloric acid solution is added to adjust the pH to 7.3, and then 35g of ethylenediamine is added. The reaction is carried out in a sealed container at 90℃ for 3h. After the reaction is completed, the mixture is cooled to room temperature, the aqueous phase is removed, and the organic phase is washed to obtain the cashew nut shell oil modified amine.

[0146] (2) Spraying

[0147] The primer was sprayed onto the outer surface of the antenna tube at a pressure of 0.20 MPa, a distance of 17 cm, and a thickness of 15 μm. After spraying, the tube was cured at room temperature for 26 hours to obtain the antenna tube with the primer.

[0148] 2. Apply polyurea coating

[0149] (1) Preparation of material A

[0150] 10g of polypropylene glycol was vacuum dehydrated at a temperature of 115℃ and a vacuum degree of 0.05kPa until the moisture content was less than 0.05wt%. Then, it was added to 2.9g of diphenylmethane diisocyanate (MDI) under a nitrogen atmosphere and reacted at 70℃ for 1.5h to obtain material A.

[0151] The molecular weight of the polyoxypropylene glycol is 2000;

[0152] (2) Preparation of material B

[0153] The composite filler and polyetheramine were premixed in a high-speed disperser at a speed of 3000 rpm. After premixing, a chain extender was added under vacuum conditions, with the vacuum degree controlled at 0.08 bar. Then, ultrasonic treatment was performed at a frequency of 30 kHz, a duration of 36 min, and a power of 145 W. After ultrasonic treatment, the mixture was degassed under vacuum at 62 °C for 30 min to obtain material B.

[0154] The mass ratio of the composite filler, polyetheramine and chain extender is 27:65:8;

[0155] The polyetheramine is polyetheramine D230;

[0156] The chain extender is a mixture of ethylenediamine and 3,5-dimethylthiotoluenediamine, wherein the mass ratio of ethylenediamine to 3,5-dimethylthiotoluenediamine is 1.4:1;

[0157] The composite filler is prepared by placing 13g of nano-silica in 80g of tannic acid solution and stirring at 54℃ for 1.5h. After stirring, the solid is filtered out and washed, then added to 80g of 30wt% ethanol solution. The temperature is increased to 62℃ at a rate of 1.5℃ / min, and 60g of silane coupling agent solution is added at a rate of 1.0g / min. After addition, the mixture is kept warm and stirred for 2.3h. After filtration, washing and drying, silane-treated nano-silica is obtained.

[0158] The particle size of the nano-silica is 30 nm;

[0159] The mass concentration of the tannic acid solution is 38 wt%.

[0160] The silane coupling agent solution is composed of a 30wt% ethanol solution, kH540 silane coupling agent, and kH550 silane coupling agent, wherein the mass ratio of the 30wt% ethanol solution, kH540 silane coupling agent, and kH550 silane coupling agent is 100:1.2:1.6.

[0161] 10g of nano-silica was evenly dispersed in 100g of toluene, and 1.4g of kH560 silane coupling agent was added for ball milling. The ball milling time was 47min, the ball milling speed was 214rpm, and the ball-to-material ratio was 4:1. After ball milling, the temperature was raised to 76℃ and the reaction was maintained at this temperature for 3.6h. After filtration, washing and drying, pretreated nano-silica was obtained.

[0162] The particle size of the nano-silica is 35 nm;

[0163] 6.7g of pretreated nano-silica and 5.0g of silane-treated nano-silica were added to 250g of anhydrous ethanol and ultrasonically dispersed at a power of 175W and a frequency of 55kHz for 45min. Then the temperature was increased to 58℃ at a rate of 0.5℃ / min and the reaction was maintained for 2.0h. The solid was filtered out, washed and dried to obtain the composite filler.

[0164] (3) Dynamic spraying

[0165] Dynamic spraying was performed on the antenna tube after the primer was applied. A spraying machine was used to spray materials A and B heated to 57°C at 16MPa. During spraying, the antenna tube after the primer was applied was placed in a rotating fixture, and the rotation speed was controlled at 4000mm / min. The angle between the spray gun and the rotating fixture was adjusted to control the free end face at 45°C and the groove surface at 90°C. The coating thickness of the antenna tube after the primer was controlled to be 2.5mm in the composite material area and 5.5mm in the metal area, resulting in an antenna tube with a polyurea coating.

[0166] The mass ratio of material A to material B is 1:1.

[0167] 3. Post-processing

[0168] After the antenna tube was coated with polyurea, it was left to stand at room temperature for 1.5 hours, and then the temperature was raised to 70°C and cured for 25 hours to obtain an oil-resistant and wear-resistant coating on the surface of the antenna tube.

[0169] Comparative Example 3-1

[0170] The changes made in Example 3 are as follows:

[0171] The primer spraying step is as follows: the primer is sprayed onto the outer surface of the antenna tube at a spraying pressure of 0.20 MPa, a spraying distance of 17 cm, and a spraying thickness of 15 μm. After spraying, the primer is cured at room temperature for 26 h to obtain the antenna tube after primer spraying.

[0172] The primer is bisphenol A type epoxy resin;

[0173] All other operations are the same.

[0174] Comparative Example 3-2

[0175] The changes made in Example 3 are as follows:

[0176] In the step of preparing the polyurea coating, the composite filler is replaced by an equal amount of nano-silica, wherein the particle size of the nano-silica is 30 nm.

[0177] All other operations are the same.

[0178] Performance testing

[0179] The antenna tubes obtained by the preparation methods of Examples 1-3, Comparative Examples 3-1, and 3-2 were coated with an oil-resistant and wear-resistant coating, and their performance was tested as follows:

[0180] 1. Basic performance

[0181]

[0182] Fracture toughness was tested using the single-sided notched beam method (SENB).

[0183] 2. Wear resistance

[0184] The antenna tubes prepared by the methods in Examples 1-3, Comparative Examples 3-1, and 3-2 were coated with oil-resistant and wear-resistant coatings as samples. Friction tests were conducted using a friction loss testing machine. Before the friction test, the coated samples were cleaned and dried, and their weight was recorded as m1. After the friction test, the coated samples were cleaned and dried, and their weight was recorded as m2. The wear rate was calculated as (m1-m2) / m1×100%. During the friction test, the test temperature was 26℃, the relative humidity was 62%, the friction speed was 250 rpm, the friction test force was 520 N, and the friction test time was 60 min. The wear rate results are as follows:

[0185]

[0186] 3. Oil resistance

[0187] The antenna tubes with oil-resistant and wear-resistant coatings obtained by the preparation methods of Examples 1-3, Comparative Examples 3-1, and 3-2 were placed in sealed containers and impregnated with hydraulic oil (Shell AeroShell Fluid 31). The hydraulic oil was used to ensure complete immersion of the wear-resistant coating on the antenna tube surface. The impregnation pressure was 8.0 MPa, and the impregnation time was 168 hours. The fracture toughness and bonding strength with the antenna tube were tested again, and the results are as follows:

[0188]

[0189] 4. Resistance to ultraviolet radiation

[0190] The antenna tubes obtained by the preparation methods of Examples 1-3, Comparative Examples 3-1, and 3-2 were subjected to ultraviolet irradiation with an oil-resistant and wear-resistant coating, and the ultraviolet intensity was controlled at 120 W / cm². 2 The irradiation time was 168 hours. The fracture toughness and bonding strength with the antenna tube were tested again, and the results are as follows:

[0191]

[0192] This invention uses a specific two-component epoxy resin as a primer. The epoxy resin possesses good adhesion and chemical resistance. Epoxy propylene butyl ether reduces viscosity and promotes the primer's penetration into the antenna tube. Cashew nut shell oil-modified amines form a dense cross-linked network with the epoxy resin, and the long-chain alkyl groups reduce surface energy, enhancing adhesion to the polyurea coating. The silanol groups after KH550 hydrolysis can bond with the antenna tube substrate, while the amino groups at the other end can cross-link with the epoxy resin, enhancing interfacial bonding. Through specific formulation ratios and spraying parameters of the epoxy primer, high adhesion of the primer layer to metal and composite material substrates is ensured. This approach effectively addresses the risk of coating peeling, providing a stable interface for subsequent functional layers. The polyurea coating is obtained through a crosslinking reaction of isocyanate prepolymer, polyetheramine, and chain extender, forming a three-dimensional network structure that improves the coating's hardness, elasticity, and wear resistance, effectively resisting oil erosion. A composite filler, made from silica, is introduced into the polyurea coating. Specifically, the silica is first treated with tannic acid to increase the number of hydroxyl groups on its surface and enhance its surface activity. Then, KH540 and KH550 silane coupling agents are used to further treat the silica. Silane-treated nano-silica is obtained, enriching its surface with amino groups. These amino groups can bond with -NCO in component A and epoxy resin in component B. Furthermore, pretreated nano-silica is obtained by treating the silica with KH560 silane coupling agent, resulting in a higher concentration of epoxy groups on its surface. This improves the compatibility between the silica and component B. Finally, the silane-treated nano-silica reacts with the pretreated nano-silica to form a chemically bonded network, enhancing its compatibility and adhesion with the primer, component A, and component B. This ensures coating uniformity and effectively prevents coating peeling. This process enhances wear resistance and densifies the coating, preventing oil penetration. It significantly improves hardness while maintaining high elasticity, overcoming the inherent limitations of traditional materials that struggle to balance elastic modulus and pressure resistance. Finally, it assists in a dynamic spraying process, combining rotating tooling with multi-angle spray gun control to achieve high-precision coverage of complex structures such as the free end and grooves of antenna tubes. This avoids the problems of missed coatings or build-up that often occur in irregularly shaped areas with traditional processes. The post-treatment stage, through gradient curing and static stress release, forms a hydrophobic functional surface, exhibiting excellent weather resistance and long lifespan characteristics in harsh environments.

[0193] Comparative Example 3-1 uses epoxy resin as the primer only. It has high polarity, high brittleness and poor toughness, and high hardness. It is easy to crack when subjected to impact, has poor oil resistance, and poor wettability. The interaction between epoxy resin and the substrate and polyurea coating is weak, which reduces the bonding strength between the coating and the substrate and ultimately reduces the overall performance of the coating.

[0194] Comparative Example 3-2 directly uses untreated silica as a filler, which has poor dispersibility and is prone to agglomeration, thus affecting conductivity. Furthermore, it has poor compatibility with polyurea coatings, which can easily cause cracks. In addition, the agglomeration of silica leads to high porosity in the coating, which allows oil molecules to easily penetrate, thereby reducing its oil resistance and ultimately shortening the service life of the coating.

[0195] Unless otherwise specified, all proportions mentioned in this invention are mass proportions, and all percentages are mass percentages.

[0196] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an oil-resistant and wear-resistant coating for the surface of an antenna tube, characterized in that, This includes spraying primer, spraying polyurea coating, and post-treatment steps; The primer coating includes primer preparation and spraying steps; The step of preparing the primer is to mix epoxy resin HY01A and epoxy resin HY01B to obtain the primer. The mass ratio of epoxy resin HY01A to epoxy resin HY01B is 1:2.8-3.2; The preparation method of the epoxy resin HY01A is as follows: bisphenol A type epoxy resin and propylene oxide butyl ether are added to a reaction vessel, stirred at 40-50℃ to obtain a homogeneous liquid, and then degassed under vacuum to obtain epoxy resin HY01A. The mass ratio of the bisphenol A type epoxy resin to the propylene oxide butyl ether is 1:0.15-0.20; The preparation method of the epoxy resin HY01B is as follows: cashew nut shell oil modified amine is stirred in a mixed solvent and completely dissolved. Then, bisphenol A type epoxy resin and kH550 silane coupling agent are added and stirred for 28-34 minutes to obtain epoxy resin HY01B. The mass ratio of the mixed solvent, cashew nut shell oil modified amine, bisphenol A type epoxy resin, and kH550 silane coupling agent is 30-50:8-12:100:1-3. The mixed solvent is a mixture of xylene and n-butanol, wherein the mass ratio of xylene to n-butanol is 7:2.8-3.2; The sprayed polyurea coating includes the steps of preparing material A, preparing material B, and dynamic spraying. The preparation step of material A is as follows: the polyol is dehydrated under vacuum at a temperature of 110-120℃ and a vacuum degree of 0.04-0.06kPa until the water content is less than 0.05wt%. Then, it is added to the polyisocyanate under a nitrogen atmosphere and reacted at 60-80℃ for 1-2 hours to obtain material A. The polyol is one of polypropylene glycol, polytetrahydrofuran ether glycol, or polyethylene adipate glycol, and the molecular weight of the polyol is 1000-2000. The polyisocyanate is one of diphenylmethane diisocyanate (MDI) and toluene diisocyanate (TDI); The mass ratio of the polyol to the polyisocyanate is 10:2.9-5.0; The preparation step of material B is as follows: premix the composite filler with polyetheramine, add a chain extender under vacuum and perform ultrasonic treatment to obtain material B; The composite filler is prepared by stirring nano-silica in a tannic acid solution, filtering out the solid, washing it, adding it to an ethanol solution, heating it to 60-64℃, adding a silane coupling agent solution to obtain silane-treated nano-silica; placing the nano-silica in toluene, adding kH560 silane coupling agent, ball milling it, reacting at 74-77℃ for 3.4-4.0 h to obtain pretreated nano-silica; adding the pretreated nano-silica and silane-treated nano-silica to anhydrous ethanol, ultrasonically dispersing it, reacting at 56-60℃ for 1.8-2.3 h to obtain the composite filler; The silane coupling agent solution is a mixture of 27-32 wt% ethanol solution, kH540 silane coupling agent, and kH550 silane coupling agent.

2. The method for preparing an oil-resistant and wear-resistant coating for an antenna tube surface according to claim 1, characterized in that, The method for preparing the cashew nut shell oil modified amine is as follows: cashew nut shell oil, formaldehyde solution and sodium hydroxide are mixed and then added to anhydrous ethanol. After stirring evenly, the temperature is raised to 65-68℃ and the reaction is stirred for 2.4-2.8h. 4.8-5.2wt% hydrochloric acid solution is added to adjust the pH to 7.2-7.

5. Then ethylenediamine is added and the reaction is carried out in a closed container at 85-95℃ for 2-4h. After the reaction is completed, the mixture is cooled to room temperature, the aqueous phase is removed, and the organic phase is washed to obtain the cashew nut shell oil modified amine. The mass-to-volume ratio of cashew shell oil, formaldehyde solution, sodium hydroxide, anhydrous ethanol, and ethylenediamine is 150-154g: 54-58mL: 8.4-8.7g: 96-100mL: 32-37g. The formaldehyde solution has a mass concentration of 32-35%.

3. The method for preparing an oil-resistant and wear-resistant coating for an antenna tube surface according to claim 1, characterized in that, The spraying step is as follows: the primer is sprayed onto the outer surface of the antenna tube at a spraying pressure of 0.15-0.25 MPa, a spraying distance of 15-20 cm, and a spraying thickness of 10-20 μm. After spraying, the primer is cured at room temperature for 24-30 h to obtain the antenna tube after primer spraying.

4. The method for preparing an oil-resistant and wear-resistant coating for an antenna tube surface according to claim 1, characterized in that, In the step of preparing material B, the mass ratio of the composite filler, polyetheramine and chain extender is 25-30:60-70:5-10; The polyetheramine is one of polyetheramines D230, D400, and T403; The chain extender is at least one of ethylenediamine, 1,4-butanediamine, 3,5-dimethylthiotoluenediamine, and diethyltoluenediamine.

5. The method for preparing an oil-resistant and wear-resistant coating for an antenna tube surface according to claim 1, characterized in that, In the preparation method of the composite filler, the mass ratio of anhydrous ethanol, pretreated nano-silica, and silane-treated nano-silica is 250:6.5-6.8:4.8-5.

2. In the method for preparing silane-treated nano-silica, the particle size of the nano-silica is 20-50 nm. The mass ratio of the nano-silica, tannic acid solution, ethanol solution, and silane coupling agent solution is 12-15:78-85:76-83:58-62; The mass concentration of the tannic acid solution is 36-40 wt%. The mass concentration of the ethanol solution is 27-32%; In the silane coupling agent solution, the mass ratio of the 27-32wt% ethanol solution, kH540 silane coupling agent, and kH550 silane coupling agent is 100:1.0-1.3:1.5-1.

8. In the method for preparing pretreated nano-silica, the particle size of the nano-silica is 30-40 nm. The mass ratio of the nano-silica, toluene, and kH560 silane coupling agent is 8-12:100:1.2-1.

5.

6. The method for preparing an oil-resistant and wear-resistant coating for an antenna tube surface according to claim 1, characterized in that, The dynamic spraying step involves dynamically spraying the antenna tube after primer application. A spraying machine is used to simultaneously spray materials A and B heated to 55-60℃ at 15-17MPa. During spraying, the antenna tube after primer application is placed in a rotating fixture, with the rotation speed controlled at 3900-4100mm / min. The angle between the spray gun and the rotating fixture is adjusted, controlling the free end face temperature to 40-50℃ and the groove surface temperature to 85-95℃. The coating thickness of the antenna tube after primer application is controlled, with the composite material area thickness at 2.0-3.0mm and the metal area thickness at 5.0-6.0mm, resulting in an antenna tube coated with a polyurea layer. The mass ratio of material A to material B is 1:0.8-1.

2.

7. The method for preparing an oil-resistant and wear-resistant coating for an antenna tube surface according to claim 1, characterized in that, The post-processing step involves letting the antenna tube with the sprayed polyurea coating stand at room temperature for 1-2 hours, then raising the temperature to 65-75°C and curing for 24-26 hours to obtain an oil-resistant and wear-resistant coating on the surface of the antenna tube.

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