A coating method for a wheel hub and a wheel hub

Abstract

The application relates to the automobile technical field and discloses a wheel hub coating method and a wheel hub. The wheel hub coating method comprises the following steps: after a wheel hub base is subjected to degreasing, pickling, water washing and drying, the wheel hub is electrostatically sprayed with plastic powder, and is solidified to obtain a coated wheel hub; the plastic powder comprises the following components in parts by weight: 50-70 parts of epoxy resin, 15-40 parts of a styrene-maleimide copolymer, 20-25 parts of an ethylene-vinyl alcohol copolymer, 10-15 parts of a filler, 4-6 parts of a degassing agent and 5-10 parts of a pigment. Through the technical scheme, the problem of poor corrosion resistance of the wheel hub after coating in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile, in particular, to a wheel hub coating method and wheel hub. BACKGROUND

[0002] The wheel hub as a safety component of the automobile plays a very important role in the use of the automobile. The coating is the last process of the production of the automobile wheel hub. Through the coating process, the corrosion resistance of the automobile wheel hub can be improved, and the safety of the automobile can be ensured. The existing coating method is often complex, the steps are tedious, and the corrosion resistance of the sprayed plastic powder is poor, which leads to the difficulty of the automobile wheel hub to face the harsh use environment. In order to further improve the corrosion resistance of the automobile wheel hub and meet the needs of different use environments, it has important practical significance to develop a new type of wheel hub coating method. SUMMARY

[0003] The present application provides a wheel hub coating method and wheel hub, which solves the problem of poor corrosion resistance of the wheel hub after coating in the related art.

[0004] The technical scheme of the present application is as follows:

[0005] The present application provides a wheel hub coating method, which comprises the following steps: after the wheel hub base is degreased, pickled, washed and dried, the plastic powder is electrostatically sprayed, and the wheel hub after coating is obtained after curing.

[0006] The plastic powder comprises the following components by weight: epoxy resin 50-70 parts, styrene-maleimide copolymer 15-40 parts, ethylene-vinyl alcohol copolymer 20-25 parts, filler 10-15 parts, degassing agent 4-6 parts, and pigment 5-10 parts.

[0007] As a further technical scheme, the mass ratio of the styrene-maleimide copolymer to the ethylene-vinyl alcohol copolymer is 1-1.5:1.

[0008] When the mass ratio of the styrene-maleimide copolymer to the ethylene-vinyl alcohol copolymer is 1-1.5:1, it is beneficial to further enhance the corrosion resistance of the wheel hub after coating.

[0009] As a further technical scheme, the filler is one or more of titanium white powder, mica powder and micro-silicon powder.

[0010] As a further technical scheme, the degassing agent is benzoin or micro-powder wax.

[0011] As a further technical scheme, the pigment is one or more of iron red, iron yellow and carbon black.

[0012] As a further technical solution, the preparation method of the plastic powder comprises the following steps: uniformly mixing the components, extruding, tabletting, crushing, and obtaining the plastic powder.

[0013] As a further technical solution, in the electrostatic spraying, the electrostatic voltage is 30-50 kV, the spraying pressure is 0.3-0.4 MPa, and the time is 6-8 s.

[0014] As a further technical solution, in the curing, the temperature is 160-170 DEG C, and the time is 10-15 min.

[0015] As a further technical solution, after the water washing, the passivation treatment is further included, and the method of the passivation treatment is as follows: spraying a passivation liquid on the surface of the hub base body after the water washing, and air-drying to obtain a hub base body after passivation.

[0016] The passivation treatment is beneficial to improving the adhesion of the plastic powder coating and the hub base body, and can enhance the corrosion resistance of the hub base body, and further improve the corrosion resistance of the hub after coating.

[0017] As a further technical solution, the passivation liquid is composed of the following components in percentage by weight: 4-6% of zinc chloride, 4-6% of copper sulfate, 3-5% of sodium nitrate, 2-4% of sodium imidazole, and 2-4% of calcium disodium edetate, and the balance is water.

[0018] The sodium imidazole and the calcium disodium edetate in the passivation liquid can synergistically enhance the passivation ability of the passivation liquid, and can improve the curing ability of the plastic powder in the subsequent process steps, enhance the cross-linking degree, and further improve the corrosion resistance of the hub after coating.

[0019] The application further provides a hub prepared by the coating method.

[0020] The working principle and beneficial effects of the application are as follows:

[0021] 1. In the application, the components of the plastic powder include styrene-maleimide copolymer and ethylene-vinyl alcohol copolymer, and the cross-linking degree of the molecular chains in the plastic powder is improved through the synergistic effect of the two, the penetration of corrosive molecules into the interior is hindered, and the corrosion resistance of the hub after coating is enhanced. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0023] In the following examples and comparative examples, the hub base is an aluminum alloy hub base, the epoxy resin is CYD-014U, the styrene-maleimide copolymer is XIRAN-3000I, the ethylene-vinyl alcohol copolymer is EVOH-F101, the titanium white has a particle size of 45 μm, the micro powder wax has a viscosity of 8500 cps, the iron red has a particle size of 45 μm, the zinc chloride has a purity of 99%, the copper sulfate has a purity of 99%, the sodium nitrate has a purity of 99%, the sodium imidazole has a purity of 99%, and the calcium disodium edetate has a purity of 99%.

[0024] Example 1

[0025] A coating method of a hub includes the following steps: after the hub base is degreased, pickled, washed, and dried, the hub base is electrostatically sprayed with plastic powder, and is cured at 160℃ for 15 min to obtain a coated hub.

[0026] In the electrostatic spraying, the electrostatic voltage is 30 kV, the spraying pressure is 0.3 MPa, and the time is 8 s.

[0027] The preparation method of the plastic powder is as follows: 50 parts of epoxy resin, 15 parts of styrene-maleimide copolymer, 20 parts of ethylene-vinyl alcohol copolymer, 10 parts of titanium white, 4 parts of micro powder wax, and 5 parts of iron red are uniformly mixed, extruded, tabletted, and crushed to obtain the plastic powder.

[0028] Example 2

[0029] A coating method of a hub includes the following steps: after the hub base is degreased, pickled, washed, and dried, the hub base is electrostatically sprayed with plastic powder, and is cured at 170℃ for 10 min to obtain a coated hub.

[0030] In the electrostatic spraying, the electrostatic voltage is 50 kV, the spraying pressure is 0.4 MPa, and the time is 6 s.

[0031] The preparation method of the plastic powder is as follows: 70 parts of epoxy resin, 40 parts of styrene-maleimide copolymer, 25 parts of ethylene-vinyl alcohol copolymer, 15 parts of titanium white, 6 parts of micro powder wax, and 10 parts of iron red are uniformly mixed, extruded, tabletted, and crushed to obtain the plastic powder.

[0032] Example 3

[0033] The difference between this example and Example 2 is that, in this example, the weight part of the styrene-maleimide copolymer is 20 parts in the preparation of the plastic powder.

[0034] Example 4

[0035] The difference between this example and Example 2 is that, in this example, the weight part of the styrene-maleimide copolymer is 25 parts in the preparation of the plastic powder.

[0036] Example 5

[0037] The difference between this example and Example 2 is that in this example, the weight part of the styrene-maleimide copolymer is 37.5 parts when preparing the plastic powder.

[0038] Example 6

[0039] The difference between this example and Example 5 is that in this example, a passivation treatment is further carried out after water washing, and the method of passivation treatment is: spraying a passivation liquid on the surface of the hub body after water washing, and air-drying to obtain a passivated hub body.

[0040] The passivation liquid is composed of the following components in weight percentage: zinc chloride 4%, copper sulfate 4%, sodium nitrate 3%, and the balance is water.

[0041] Example 7

[0042] The difference between this example and Example 6 is that in this example, the passivation liquid is composed of the following components in weight percentage: zinc chloride 4%, copper sulfate 4%, sodium nitrate 3%, sodium imidazole 4%, and the balance is water.

[0043] Example 8

[0044] The difference between this example and Example 6 is that in this example, the passivation liquid is composed of the following components in weight percentage: zinc chloride 4%, copper sulfate 4%, sodium nitrate 3%, and calcium sodium edetate 4%, and the balance is water.

[0045] Example 9

[0046] The difference between this example and Example 6 is that in this example, the passivation liquid is composed of the following components in weight percentage: zinc chloride 4%, copper sulfate 4%, sodium nitrate 3%, sodium imidazole 2%, and calcium sodium edetate 2%, and the balance is water.

[0047] Example 10

[0048] The difference between this example and Example 6 is that in this example, the passivation liquid is composed of the following components in weight percentage: zinc chloride 6%, copper sulfate 6%, sodium nitrate 5%, sodium imidazole 4%, and calcium sodium edetate 4%, and the balance is water.

[0049] Comparative Example 1

[0050] The difference between this example and Example 1 is that in this example, no styrene-maleimide copolymer and ethylene-vinyl alcohol copolymer are added when preparing the plastic powder.

[0051] Comparative Example 2

[0052] The difference between the present comparative example and example 1 is only that, in the present comparative example, no styrene-maleimide copolymer is added when preparing the plastic powder, and the weight part of ethylene-vinyl alcohol copolymer added is 35 parts.

[0053] Comparative example 3

[0054] The difference between the present comparative example and example 1 is only that, in the present comparative example, no ethylene-vinyl alcohol copolymer is added when preparing the plastic powder, and the weight part of styrene-maleimide copolymer added is 35 parts.

[0055] The corrosion resistance of the coated wheel hubs of examples 1-10 and comparative examples 1-3 is tested according to the following test method: a salt spray solution (consisting of 50 g / L of sodium chloride solution and 0.26 g / L of copper chloride solution, and the pH value is adjusted to 3.0 with glacial acetic acid) is prepared, and the coated wheel hub to be tested is placed in a test box, the test surface is at an angle of 20° to the vertical, the test temperature is controlled at 50°C, and the salt spray deposition rate is 1.5 mL / h, when the test surface appears to fall off, the test is ended, and the test time is recorded. The test results are shown in Table 1 below.

[0056] Table 1: Corrosion resistance test results

[0057]

[0058] Comparing example 1 with comparative examples 1-3 shows that, through the synergistic effect of styrene-maleimide copolymer and ethylene-vinyl alcohol copolymer in the plastic powder, the corrosion resistance of the coated wheel hub can be significantly improved.

[0059] Comparing examples 2-3 with examples 4-5 shows that, when the mass ratio of styrene-maleimide copolymer to ethylene-vinyl alcohol copolymer is 1-1.5:1, it is beneficial to further enhance the corrosion resistance of the coated wheel hub. Comparing example 5 with examples 6-10 shows that, by adding a passivation treatment process after washing, it is beneficial to further enhance the corrosion resistance of the coated wheel hub. Comparing example 9 with examples 6-8 shows that, sodium imidazole and calcium disodium edetate in the passivation solution have a synergistic effect, which can further improve the corrosion resistance of the coated wheel hub.

[0060] The above is only a preferred embodiment of the present application, and is not intended to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for painting a wheel hub, characterized in that, Includes the following steps: After degreasing, pickling, washing and drying, the wheel hub substrate is electrostatically sprayed with plastic powder and cured to obtain the coated wheel hub. The powder coating comprises the following components in parts by weight: 50-70 parts epoxy resin, 15-40 parts styrene-maleimide copolymer, 20-25 parts ethylene-vinyl alcohol copolymer, 10-15 parts filler, 4-6 parts degassing agent, and 5-10 parts pigment. The water washing process also includes a passivation treatment, which is performed by spraying a passivation solution onto the surface of the water-washed wheel hub substrate and allowing it to air dry to obtain a passivated wheel hub substrate. The passivation solution consists of the following components by weight percentage: zinc chloride 4%~6%, copper sulfate 4%~6%, sodium nitrate 3%~5%, imidazole sodium 2%~4%, calcium sodium edetate 2%~4%, and the balance being water.

2. The method for painting a wheel hub according to claim 1, characterized in that, The mass ratio of the styrene-maleimide copolymer to the ethylene-vinyl alcohol copolymer is 1~1.5:

1.

3. The method for painting a wheel hub according to claim 1, characterized in that, The filler is one or more of titanium dioxide, mica powder, and microsilica powder.

4. The method for painting a wheel hub according to claim 1, characterized in that, The degassing agent is benzoin or micronized wax.

5. The method for painting a wheel hub according to claim 1, characterized in that, The pigment is one or more of iron oxide red, iron oxide yellow, and carbon black.

6. The method for painting a wheel hub according to claim 1, characterized in that, The preparation method of the plastic powder includes the following steps: mixing the components evenly, extruding, pressing into sheets, and crushing to obtain the plastic powder.

7. The method for painting a wheel hub according to claim 1, characterized in that, During the electrostatic spraying process, the electrostatic voltage is 30~50kV, the spraying pressure is 0.3~0.4MPa, and the time is 6~8s.

8. A wheel hub, characterized in that, It is prepared by the coating method according to any one of claims 1 to 7.

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