High-weather-resistant coating for wheel hub and preparation method thereof

Abstract

The application discloses a kind of high weatherability coating for wheel hub and preparation method thereof, and belongs to the technical field of coating composition, wherein high weatherability coating for wheel hub is prepared by acrylate resin, polyester resin containing benzene ring structure, methyl ether amino resin, ultraviolet absorber, light stabilizer, epoxy resin, high-boiling alcohol ether solvent, leveling agent, defoaming agent portion according to mass fraction;The application uses acrylate resin, epoxy resin amino resin, polyester resin containing benzene ring structure, the rigid characteristics of benzene ring endows the resin with hardness, and the stable structure characteristics of benzene ring endows the resin with chemical resistance, solves the problem of flexibility and stone impact resistance, high salt fog resistance;Mask light paint is designed as hard chain segment mainly to ensure the hardness of paint film, increase length can absorb part of energy through its flexibility when being impacted by external force, reduce the probability of fracture.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coating compositions, and particularly relates to a high-weatherability coating for a wheel hub; and particularly relates to a preparation method of the high-weatherability coating for the wheel hub. BACKGROUND

[0002] With the continuous development of the motorcycle industry, its supporting products have also been developed. The wheel hub, as a very important component of the motorcycle, is also paid more and more attention by the motorcycle manufacturers. Therefore, the requirements for the appearance decoration and high performance of the wheel hub paint are higher and higher. The motorcycle wheel hub manufacturers have very strict requirements for the motorcycle wheel hub paint, and the basic performance such as flexibility, adhesion, hardness, stone impact, impact, lead-free property, gasoline resistance, humidity resistance, water resistance, heat resistance, acid and alkali resistance, weather resistance and salt spray resistance long-term experiment performance need to be detected, and the appearance requirement is also very high.

[0003] In the prior art, the motorcycle wheel hub is exposed to the comprehensive environment of ultraviolet radiation, temperature and humidity change, and acid rain erosion for a long time. The conventional coating is prone to powdering, discoloration and cracking due to poor weather resistance of the resin and imperfect ultraviolet resistance additive system. In addition, the wheel hub continuously bears dynamic impact load during the driving of the motorcycle, and the coating must have excellent flexibility to resist deformation stress. The traditional coating increases the hard component of the epoxy resin to improve the hardness, which increases the brittleness of the coating and easily produces microcracks or even peeling under impact working conditions, greatly reducing the overall protective life of the coating. Therefore, the present application provides a high-weatherability coating for a wheel hub and a preparation method thereof. SUMMARY

[0004] The present application aims to provide a high-weatherability coating for a wheel hub and a preparation method thereof. The high-weatherability motorcycle wheel hub coating is prepared by using acrylic resin, amino resin, the weather resistance of the pigments themselves, and adding a certain amount of ultraviolet absorber in the formula. The weather resistance, supporting performance and physical and chemical properties of the coating are improved by adjusting the selection of the resin, additive and pigment filler. Finally, the high-weatherability motorcycle wheel hub coating reaches the national standard.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A high-weatherability coating for a wheel hub, characterized in that: the high-weatherability coating for the wheel hub is prepared from 50-70 parts of acrylic ester resin, 10-30 parts of polyester resin containing benzene ring structure, 15-25 parts of methyl etherified amino resin, 1-5 parts of ultraviolet absorber, 0.5-3 parts of light stabilizer, 5-15 parts of epoxy resin, 20-40 parts of high-boiling alcohol ether solvent, 0.1-1 part of leveling agent, and 0.1-0.8 part of defoaming agent, according to the mass fraction;

[0007] The benzene ring content of the polyester resin containing benzene ring structure accounts for 30%-50% of the total mass of its molecular structure;

[0008] The hydroxyl value of the acrylate resin is 90-130 mgKOH / g, and it does not contain lead compounds;

[0009] The coating after curing of the composition meets the requirements of gloss loss ≤10% after 1000h of QUV artificial aging, discoloration grade ≤1 level, salt spray resistance ≥2000h, single-side corrosion ≤1mm, pencil hardness ≥2H, impact resistance ≥50kg·cm, flexibility ≤1mm, and wear resistance (1000r / 1000g) ≤20mg.

[0010] Preferably, the branching degree of the polyester resin containing benzene ring structure is 10%-35%, at least 30% of the active hydroxyl groups in the molecular chain are located at the end of the branch, the glass transition temperature (Tg) of the polyester resin containing benzene ring structure is 70-85℃, and the benzene ring content is 35%-45%.

[0011] Preferably, the ultraviolet absorber is a complex of benzotriazole and triazine with a mass ratio of (1.5-3):1.

[0012] Preferably, the light stabilizer is a polymeric hindered amine light stabilizer (HALS) with a molecular weight >2000 g / mol, and the mass ratio of the ultraviolet absorber to the light stabilizer is (2-4):1.

[0013] Preferably, the acrylate resin contains glycidyl ether groups in the branch, and the content accounts for 0.5%-1.2% of the total mass of the resin.

[0014] Preferably, the high-boiling alcohol ether solvent is a mixture of dipropylene glycol methyl ether acetate (DPMA) and divalent acid ester (DBE) with a mass ratio of (1-1.5):1.

[0015] A preparation method of a high-weatherability coating for a hub, which is used to prepare the above-mentioned high-weatherability coating for a hub, comprising the following steps:

[0016] S1, prepolymer synthesis:

[0017] The polyester resin containing benzene ring structure and the high-boiling alcohol ether solvent are put into a reaction kettle, stirred under nitrogen protection, heated to 130-145℃, and kept at this temperature for 2-3h to obtain prepolymer A;

[0018] The acrylate resin, methyl ether amino resin, and epoxy resin are mixed and dispersed at high speed for 40-60min at 80-100℃ to obtain prepolymer B;

[0019] S2, dispersion of functional additives:

[0020] UV absorber, light stabilizer is added to the prepolymer A of step S1, and shearing dispersion is carried out at a rotating speed of 1200-1500 r / min for 30-40 min;

[0021] The leveling agent and defoaming agent are added, and the temperature is maintained at 70-80℃, and the dispersion is continued for 15-20 min;

[0022] S3, miscible and post-processing:

[0023] The prepolymer B is slowly added to the system of step S2, and the adding speed is controlled to be ≤10 parts / min, and stirring is carried out at a rotating speed of 500-800 r / min;

[0024] The temperature is raised to 95-105℃, and the reaction is carried out for 1.5-2 h, and then the material is discharged after being filtered through a 200 mesh screen.

[0025] Preferably, the synthesis process of the polyester resin containing benzene ring structure in the step S1 is as follows:

[0026] The binary acid anhydride containing 30-50 mol% benzene ring structure monomer is mixed with polyol according to a molar ratio of carboxyl:hydroxyl=1:(1.05-1.2); melt condensation is carried out at 150-160℃, vacuum is extracted to-0.08--0.09 MPa, and the reaction is carried out until the acid value is ≤5 mgKOH / g; 0.5-1% antioxidant 1010 based on the total mass is added, and the temperature is lowered to 80℃ to discharge.

[0027] Preferably, when the UV absorber and light stabilizer are added in the step S2, a three-stage gradient temperature raising method is adopted:

[0028] The first stage: 1 / 3 of the additives is added at 60℃, and dispersion is carried out at 800 r / min for 10 min;

[0029] The second stage: the remaining 1 / 2 of the additives is added after the temperature is raised to 75℃, and dispersion is carried out at 1500 r / min for 15 min;

[0030] The third stage: the remaining additives are added after the temperature is raised to 85℃, and dispersion is carried out at 2000 r / min for 10 min.

[0031] The technical effects and advantages of the present application are as follows:

[0032] The acrylic resin, epoxy resin amino resin, and polyester resin containing benzene ring structure are used, the rigid characteristics of benzene ring give the resin hardness, and the stable structure characteristics of benzene ring give the resin chemical resistance, and the problems of flexibility, stone chip resistance, and high salt spray resistance are solved;

[0033] The lead-free high-hydroxyl value thermosetting acrylic resin and methyl etherified amino resin solve the problems of high hardness, high gloss, and high weather resistance;

[0034] The main chain segment is designed as a hard chain segment mainly to ensure the hardness of the paint film, increase the length and absorb part of the energy when subjected to external force impact through its flexibility, and reduce the probability of rupture; increasing the degree of branching forms a more compact network structure after crosslinking, thereby forming a tough and excellent comprehensive performance coating film;

[0035] More active functional groups are designed into the branched chain, which can improve the crosslinking efficiency and avoid excessive functional groups on the main chain from being shielded by the branched chain, thereby remaining in the paint film and reducing the water resistance and weather resistance of the paint film. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] The present application provides a kind of high weatherability coating for wheel hub and preparation method thereof, wherein high weatherability coating for wheel hub is prepared by acrylate resin, polyester resin containing benzene ring structure, methyl ether amino resin, ultraviolet absorber, light stabilizer, epoxy resin, high boiling point alcohol ether solvent, leveling agent, antifoaming agent portion according to mass fraction;

[0038] The benzene ring content of the polyester resin containing benzene ring structure accounts for 30-50% of the total mass of its molecular structure;

[0039] The hydroxyl value of the acrylate resin is 90-130 mgKOH / g, and it does not contain lead compound;

[0040] The coating after curing of the composition meets the requirements of gloss loss ≤10% after 1000h of QUV artificial aging, discoloration grade ≤1 level, salt spray resistance ≥2000h, single side corrosion ≤1mm, pencil hardness ≥2H, impact resistance ≥50kg·cm, flexibility ≤1mm, and wear resistance (1000r / 1000g) ≤20mg.

[0041] As an option, it also includes flaky zinc-aluminum composite anti-rust pigment with a particle size D50 of 8-15 μm;The flaky zinc-aluminum composite pigment is modified by silane coupling agent KH-560, and the surface coating rate is 85%-95%;

[0042] It also includes nano-silicon dioxide modified polysiloxane leveling agent, and the nano-particle surface grafting rate is 65%-80%;

[0043] The above-mentioned benzene ring polyester resin solves the contradiction between flexibility, stone chip resistance and salt mist resistance; the rigidity of the benzene ring gives hardness, and the stable structure improves chemical resistance, and the content limitation ensures the realization of the function; the hydroxyl value of the acrylic acid + methyl ether amino resin realizes high hardness / high gloss / high weather resistance, and the weather resistance of the methyl ether amino resin is better than that of the butyl ether; the external absorbent / light stabilizer synergistically resists ultraviolet degradation and breaks through the bottleneck of weather resistance;

[0044] It should be noted that the branching degree of the polyester resin containing a benzene ring structure is 10%-35%, at least 30% of the active hydroxyl groups in the molecular chain are located at the end of the branch chain, the glass transition temperature (Tg) of the polyester resin containing a benzene ring structure is 70-85℃, and the benzene ring content is 35%-45%;

[0045] The ultraviolet absorber is a complex of benzotriazole and triazine, and the mass ratio is (1.5-3):1;

[0046] The light stabilizer is a polymeric hindered amine light stabilizer (HALS) with a molecular weight of >2000 g / mol, and the addition amount is 1.2-2.5 parts;

[0047] The mass ratio of the ultraviolet absorber to the light stabilizer is (2-4):1;

[0048] The glycidyl ether group is contained in the branched chain of the acrylate resin, and the content accounts for 0.5%-1.2% of the total mass of the resin;

[0049] The high-boiling alcohol ether solvent is a mixture of dipropylene glycol methyl ether acetate (DPMA) and divalent acid ester (DBE) with a mass ratio of (1-1.5):1

[0050] In addition, the total lead content of the composition is ≤50ppm, and there is no phthalate plasticizer.

[0051] Further, a preparation method of a high-weather-resistant coating for a hub, the method is used for preparing the high-weather-resistant coating for the hub, and comprises the following steps:

[0052] S1, prepolymer synthesis: the polyester resin containing a benzene ring structure and the high-boiling alcohol ether solvent are put into a reaction kettle, stirred under nitrogen protection, heated to 130-145℃, and kept for 2-3h to obtain a prepolymer A;

[0053] The acrylate resin, the methyl ether amino resin and the epoxy resin are mixed and dispersed at a high speed for 40-60min at 80-100℃ to obtain a prepolymer B;

[0054] In the step S1, the synthesis process of the polyester resin containing a benzene ring structure is:

[0055] The binary anhydride (containing 30-50 mol% benzene ring structure monomer) is mixed with the polyol at a molar ratio of carboxyl:hydroxyl=1:(1.05-1.2);

[0056] Melt condensation at 150-160℃, vacuum extraction to-0.08--0.09MPa, reaction to acid value≤5mgKOH / g;

[0057] Add 0.5-1% antioxidant 1010 based on the total mass, cool to 80℃ and discharge;

[0058] S2, functional additive dispersion: add ultraviolet absorber and light stabilizer to the prepolymer A of step S1, shear dispersion at a speed of 1200-1500r / min for 30-40min;

[0059] Add leveling agent and defoaming agent, maintain temperature at 70-80℃ and continue to disperse for 15-20min;

[0060] Specifically, when adding ultraviolet absorber and light stabilizer in step S2, three-stage gradient heating method is adopted:

[0061] First stage: add 1 / 3 of the additive at 60℃, disperse at 800r / min for 10min;

[0062] Second stage: heat to 75℃, add 1 / 2 of the remaining additive, disperse at 1500r / min for 15min;

[0063] Third stage: heat to 85℃, add the remaining additive, disperse at 2000r / min for 10min;

[0064] In addition, the dispersion process is carried out in a weak acid environment with pH value of 5-6.5, and acetic acid is used to adjust the pH;

[0065] S3, miscibility and post-treatment: slowly add the prepolymer B to the system of step S2, control the adding speed≤10 parts / min, and stir at a speed of 500-800r / min;

[0066] Heat to 95-105℃ and react for 1.5-2h, filter through a 200 mesh screen and discharge;

[0067] It should be noted that before miscibility in step S3, add flaky zinc-aluminum composite anti-rust pigment (5-10 parts), and use a nano sand mill to grind at a speed of 4000-5000r / min to a fineness≤15μm; the flaky zinc-aluminum composite pigment is pretreated: dilute KH-560 silane coupling agent with ethanol to a concentration of 10wt%, mix at a mass ratio of pigment: coupling agent=100:5; treat at an ultrasonic power of 300W and a temperature of 50℃ for 20min, and dry for standby.

[0068] Example 1

[0069] The formulation of the high-weatherability coating for wheel hubs in this example is as follows:

[0070] benzene ring-containing polyester resin (branching degree 18%, Tg 76°C) 18 parts; acrylate resin (hydroxyl value 110 mgKOH / g) 58 parts; methyl etherified amino resin 20 parts; epoxy resin (EEW 450) 8 parts; ultraviolet absorber (benzotriazole:triazine = 1.5:1) 2 parts; light stabilizer (polymeric HALS, Mw 2800) 1.5 parts; flaky zinc-aluminum composite pigment (D50 10 μm) 7 parts; nano-silica modified polysiloxane leveling agent 0.8 parts; defoaming agent (BYK-066N) 0.3 parts; high-boiling alcohol ether solvent (DPMA:DBE = 1.2:1) 32 parts;

[0071] The preparation parameters are as follows: prepolymer A synthesis at 138°C for 2.5 h; two-stage gradient (65°C+80°C) for auxiliary dispersion; 8 parts / min for prepolymer B mixing speed; and filtration after 1.8 h of final reaction at 100°C;

[0072] The high-weatherability coating for wheel hubs prepared in this example has the following properties: mechanical synergy, hardness up to 2H (pencil hardness) passed 1 mm shaft bending test (ISO 1519), stone chip resistance (1 kg sand 30° angle impact) without peeling; weathering durability, ΔΕ = 0.7 (gray paint film) after QUV 1500 h, and exfoliation <0.5 mm after salt spray 2500 h; and construction adaptability, viscosity unchanged for 4 h at 25°C (Ford Cup No. 4), meeting the continuous spraying requirements of motorcycle factories.

[0073] Example 2

[0074] The formulation of the high-weatherability coating for wheel hubs in this example is as follows:

[0075] benzene ring-containing polyester resin (benzene ring content 42%, branched terminal hydroxyl 38%) 25 parts; acrylate resin (glycidyl ether group content 0.8%) 65 parts; methyl etherified amino resin 22 parts; epoxy resin 12 parts; ultraviolet absorber (benzotriazole:triazine = 3:1) 4 parts; light stabilizer 2.2 parts; flaky zinc-aluminum composite pigment (KH-560 coating rate 90%) 9 parts; leveling agent 1.2 parts; defoaming agent 0.6 parts; high-boiling alcohol ether solvent (DPMA:DBE = 1.5:1) 38 parts;

[0076] The preparation parameters are as follows: prepolymer A at 142°C for 2 h; three-stage gradient dispersion (60°C+75°C+85°C) for ultraviolet system; addition of nano-sand-milled pigment (fineness 12 μm); and final reaction at 105°C for 2 h;

[0077] The high-weatherability coating prepared in the embodiment has strong ultraviolet shielding and gloss retention rate of 94.5% (ASTM D523) after 18 months of exposure, far exceeding that of commercially available competitive products (≤80%); the coating has extreme temperature tolerance, and no cracks are generated in the coating after 150 ℃ thermal shock immediately after being frozen at -40 ℃ for 24 h; the corrosion protection is upgraded, and the substrate rust area is less than 0.1% after 2000 h of acid salt spray (pH 3.5) test.

[0078] Example 3

[0079] Different from examples 1-2, the formulation of the high-weatherability coating for the wheel hub in the embodiment is as follows:

[0080] 12 parts of a polyester resin containing a benzene ring (synthesized without a lead catalyst); 52 parts of an acrylate resin; 18 parts of a methyl etherified amino resin; 6 parts of a small molecule latent epoxy curing agent (replacing part of the epoxy resin); 1.8 parts of an ultraviolet absorber; 0.8 parts of a light stabilizer; 6 parts of flaky zinc-aluminum composite pigment; 0.4 parts of a leveling agent; 0.2 parts of a defoaming agent; and 28 parts of a high-boiling-point alcohol ether solvent (pure DBE).

[0081] The preparation parameters are as follows: the dispersion condition of the prepolymer B is adjusted to pH 6.0 (adjusted by acetic acid); the latent curing agent is added cold during the miscible stage; and the VOC is reduced to 42 g / L by devolatilization under reduced pressure (-0.07 MPa) after reaction at 95 ℃ for 1.5 h.

[0082] The high-weatherability coating prepared in the embodiment is environmentally friendly and compliant, passes the EU ELV directive test (lead content <28 ppm), and no phthalate is detected; the coating is efficiently cured, and the surface dry time is 9 min (GB / T 1728) when baked at 140 ℃, which is suitable for thin coating process of aluminum alloy wheel hubs; and the coating has cycle durability, and no gravel impact pit points and stress cracks are generated after 20,000 km of actual road test of a motorcycle.

[0083] According to the above, the effect differences of the three groups of examples of the present application are as shown in Table 1.

[0084] Table 1

[0085]

[0086] Differential value table

[0087] In summary, the present application uses an acrylate resin, an epoxy resin, an amino resin, and a polyester resin containing a benzene ring structure. The rigid characteristics of the benzene ring endow the resin with hardness, and the stable structural characteristics of the benzene ring endow the resin with chemical resistance, solving the problems of flexibility, stone chip resistance, and high salt spray resistance.

[0088] The use of a lead-free high-hydroxyl-value thermosetting acrylate resin and a methyl etherified amino resin solves the problems of high hardness, high gloss, and high weatherability.

[0089] The hard chain segment of the cover light paint is designed as a main chain segment, which mainly ensures the hardness of the paint film, increases the length, and can absorb part of the energy through its flexibility when subjected to external force impact, thereby reducing the probability of rupture; increasing the degree of branching forms a more compact network structure after crosslinking, thereby forming a tough and excellent comprehensive performance coating film.

[0090] Designing more active functional groups into the branched chain can improve the crosslinking efficiency and avoid excessive functional groups on the main chain from being shielded by the branched chain, thereby failing to achieve crosslinking, remaining in the paint film, and reducing the water resistance and weather resistance of the paint film.

[0091] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application 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 replacements to some technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made shall be included in the protection scope of the present application.

Claims

1. A high weather resistant coating for a wheel hub, characterized by: The hub is prepared from 50-70 parts of acrylate resin, 10-30 parts of polyester resin containing benzene ring structure, 15-25 parts of methyl etherified amino resin, 1-5 parts of ultraviolet absorber, 0.5-3 parts of light stabilizer, 5-15 parts of epoxy resin, 20-40 parts of high-boiling alcohol ether solvent, 0.1-1 part of leveling agent, and 0.1-0.8 part of defoaming agent by mass fraction, and the high-weather-resistant coating is prepared from the above components; The benzene ring content of the polyester resin containing benzene ring structure accounts for 30-50% of the total mass of the molecular structure; The hydroxyl value of the acrylate resin is 90-130 mgKOH / g, and the acrylate resin does not contain lead compounds; The coating after curing of the composition meets the requirements of gloss loss ≤10% after 1000h of QUV artificial aging, discoloration grade ≤1 level, salt spray resistance ≥2000h, single-side corrosion ≤1mm, pencil hardness ≥2H, impact resistance ≥50kg·cm, flexibility ≤1mm, and wear resistance (1000r / 1000g) ≤20mg.

2. The high weather resistant coating for a wheel hub according to claim 1, characterized by, The branching degree of the polyester resin containing benzene ring structure is 10-35%, at least 30% of the active hydroxyl groups in the molecular chain are located at the end of the branch, the glass transition temperature (Tg) of the polyester resin containing benzene ring structure is 70-85℃, and the benzene ring content is 35-45%.

3. The high weather resistant coating for a wheel hub according to claim 1, characterized by, The ultraviolet absorber is a complex of benzotriazole and triazine, and the mass ratio is (1.5-3):

1.

4. The high weather resistant coating for a wheel hub according to claim 3, characterized by, The light stabilizer is a polymeric hindered amine light stabilizer (HALS) with a molecular weight of >2000 g / mol, and the mass ratio of the ultraviolet absorber to the light stabilizer is (2-4):

1.

5. The high weather resistant coating for a wheel hub according to claim 1, wherein The acrylate resin contains glycidyl ether groups in the branched chain, and the content accounts for 0.5-1.2% of the total mass of the resin.

6. The high weather resistant coating for a wheel hub according to claim 1, wherein The high-boiling alcohol ether solvent is a mixture of dipropylene glycol methyl ether acetate (DPMA) and divalent acid ester (DBE) with a mass ratio of (1-1.5):

1.

7. A method for producing a high weather resistant coating for a wheel hub, the method being for producing the high weather resistant coating for a wheel hub according to any one of claims 1 to 6, characterized by, The method comprises the following steps: S1, prepolymer synthesis: The polyester resin containing benzene ring structure and the high-boiling alcohol ether solvent are put into a reaction kettle, stirred under nitrogen protection, heated to 130-145℃, and kept for 2-3h to obtain prepolymer A; The acrylate resin, methyl etherified amino resin, and epoxy resin are mixed and dispersed at a high speed for 40-60min at 80-100℃ to obtain prepolymer B; S2, dispersion of functional additives: The ultraviolet absorber and light stabilizer are added to the prepolymer A of step S1, and sheared and dispersed at a speed of 1200-1500r / min for 30-40min; The leveling agent and defoaming agent are added, and the temperature is maintained at 70-80℃ for continuous dispersion for 15-20min; S3, mixing and post-treatment: The prepolymer B is slowly added to the system of step S2, and the adding speed is controlled to be ≤10 parts / min, and the stirring speed is 500-800r / min; The temperature is raised to 95-105℃ and reacted for 1.5-2h, then filtered through a 200-mesh screen, and discharged.

8. The production method of the high weather resistant coating for a wheel hub according to claim 7, characterized by, The synthesis process of the polyester resin containing benzene ring structure in step S1 is as follows: The binary anhydride containing 30-50 mol% benzene ring structure monomer is mixed with polyol according to the molar ratio of carboxyl:hydroxyl=1:(1.05-1.2); melt condensation at 150-160℃, vacuum extraction to-0.08--0.09MPa, reaction to acid value≤5mgKOH / g; add 0.5-1% antioxidant 1010 of total mass, cooling to 80℃ discharge.

9. The production method of the high weather resistant coating for a wheel hub according to claim 7, characterized by, When the ultraviolet absorber and light stabilizer are added in the step S2, a three-stage gradient heating method is used: First stage: 60℃, add 1 / 3 of the additives, disperse at 800r / min for 10min; Second stage: heat to 75℃, add 1 / 2 of the remaining additives, disperse at 1500r / min for 15min; Third stage: heat to 85℃, add the remaining additives, disperse at 2000r / min for 10min.

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